WO2005020197A1

WO2005020197A1 - A multi image display unit

Info

Publication number: WO2005020197A1
Application number: PCT/AU2004/001139
Authority: WO
Inventors: Bob Van Der Zijpp
Original assignee: Admotion Holdings Pty Ltd
Priority date: 2003-08-25
Filing date: 2004-08-25
Publication date: 2005-03-03
Also published as: CN1871629A

Abstract

A display apparatus for sequentially displaying sets of image pixels corresponding with discrete images interlaced on a transparent mosaic (10) through an aperture pattern formed in a substantially opaque mask (11) and including a housing containing a platen member (14), at least one platen mount, a mask holder assembly for releasably mounting said mask (11) thereon, at least one adjustment assembly for, upon adjustment thereof, adjusting the position of said platen member (14) relative to said opaque mask (11) and a drive assembly including a mounting assembly for mounting said mosaic (10) relative thereto and operative to drive said mosaic in a predetermined path corresponding with said aperture pattern, said adjustment device adapted to adjust the positioning of said mosaic relative to said opaque mask by following a predetermined path to selectively align corresponding components of said images with the respective said apertures.

Description

A MULTI-IMAGE DISPLAY UNIT Field of the Invention. The present invention relates to advertising displays and, more particularly, to a compact display apparatus for sequentially displaying multiple images formed on a single transparency. Background Art. With the advent of modern display advertising, limitations on advertising budgets and limited locations for display to high densities of consumers, a great demand has arisen for displaying multiple advertisements at individual popular display locations thereby enabling a number of advertisers to benefit from a single location or allowing a number of different products of the same advertiser to be displayed. Numerous different methods and devices have been proposed for preparing and displaying such advertisements. Many such devices involve relatively unwieldy mechanical elements driven by complex drive mechanisms which require a certain degree of mechanical precision. Thus, in addition to the expense of original manufacture, the user is often faced with expensive maintenance. hi addition, operation of these current drive mechanisms tend to produce an undesirable amount of noise. Typically, these devices are used in public retail outlets or other public locations. The noise level of the drive mechanism frequently predominates over the background music being played at such locations. This noise detracts from the overall environment sought by the retailers at the location where the advertising display is positioned. One such apparatus used in the advertising field has a transparent image screen which contains a mosaic of four discrete images formed from pixels which are interwoven in a predetermined arrangement such that each of the images are selected by precise positioning of the screen in four different positions relative to a grid mask which masks out all but pixels of a selected image. A platen comprising a platen surface mounts the image screen and is moveable through a precise pattern for selecting the pixels, and thereby the image, to be projected. A pair of arms are coupled to the platen and an eccentric drive and are driven by the eccentric drive to advance the platen positively through the pattern. No means is provided for efficiently adjusting the mask relative to the transparent sheet in the event the mask and screen are not in proper registration with one. another. Yet another device which includes a translucent image screen comprising a mosaic of discrete images formed by relatively small translucent pixels interlaced and arranged in uniform groups for sequential alignment with an aperture pattern formed on a stationary mask is disclosed in U.S. Pat. No. 4,897,802 to Atkinson et al., assigned to the assignee of the present application. The device exhibits excellent operational characteristics. However, the device incorporates a drive motor mounted at each of the respective corners of the apparatus for displacing the mosaic relative to the grid mask to sequentially display the discrete images formed on the mosaic. In addition, no means is provided for efficiently adjusting either the mask or mosaic relative to one another in order to conveniently align the mask and mosaic in the event the mask and mosaic are not properly aligned. Still another prior art device designed for sequentially displaying a plurality of images formed on one sheet is disclosed in U.S. Pat. No. 5,440,214 to Peeters, likewise assigned to the assignee of the present invention. The device disclosed in the patent is a low cost, efficient apparatus that provides for the sequential display of multiple high resolution images in a fast and accurate manner. This device, while having been well received commercially is relatively expensive to manufacture and presents some challenge to adjustment and maintenance of alignment. order to gain a high quality display of the respective images, the apertures in the mask and matching sections in the mosaic must be kept small. In most cases, the apertures are approximately 1 mm² although this can vary. With the small size of the apertures, it is important to positively and accurately locate the aperture section over the corresponding image section both when setting the unit and when the unit is operating. If there is any misalignment it will result in the observer seeing part of another image interspersed with the first, or what is termed "ghosting". The tolerance to get a high quality image can be as low a 1/100^th of a millimetre. Another important issue is that the image and the mask should be maintained in close contact with each other so that when the image is viewed from an angle, the possibility of seeing another of the mosaiced images is reduced. Some of the issues which can affect the quality of the image are expansion due to temperature, impact and vibration as well as wear to the unit. As such, it will be appreciated that there continues to be a need for a compact display apparatus which is inexpensive to manufacture and allows for efficient adjustment in order to maintain the mosaic and mask in proper spatial relation to allow for precise registration of the images on the mosaic with the aperture pattern on the mask as one of the two is displaced relative to the other It will be clearly understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country. Summary of the Invention. The present invention is directed to a multi image display unit, which may at least partially overcome at least one of the abovementioned disadvantages or provide the consumer with a useful or commercial choice. In one form the invention resides in a display apparatus for sequentially displaying sets of image portions corresponding with discrete images interlaced on a transparent mosaic through an aperture pattern formed in a substantially opaque mask and including: i. a housing containing a. a platen member, b. at least one platen mount, c. a mask holder assembly for releasably mounting said mask thereon; d. at least one adjustment assembly for, upon adjustment thereof, adjusting the position of said mosaic relative to said opaque mask; and e. a drive assembly including a mounting assembly for mounting said mosaic relative thereto and operative to drive said mosaic in a predetermined path corresponding with said aperture pattern, said adjustment device adapted to adjust the positioning of said mosaic relative to said opaque mask by following a predetermined path to selectively align corresponding components of said images with the respective said apertures. One typical undesirable characteristic is that after properly aligning the mosaic with the mask and operating the apparatus for some time, the mask and mosaic may become slightly misaligned. This will cause the apertures of the mask to be aligned with portions of image pixels corresponding with multiple images rather than with the pixels of only one image, causing the device to display a blurred double image, hi relatively compact display apparatus, due to the relatively small dimensions of the image pixels and the apertures on the mask as well as the close proximity of the viewer of the display, even the slightest degree of misalignment can result in the undesirable display of a distorted double image. The adjustment assembly may typically be an optical alignment system and may include at least one sensor, typically an infrared sensor for a 2 or 3-image display apparatus (horizontal or vertical movement only or single dimension movement) and more preferably 3 sensors for a 4-image display (horizontal and vertical movement or two dimensional movement). The at least one infrared sensor will typically be mounted in a fixed position relative to the mosaic and/or mask. The predetermined path may suitably be controlled by a programmable logic controller (PLC). The PLC may suitably control the movement of the mosaic or platen relative to the mask to align the image correctly with respect to the aperture pattern in the mask at the starting point of a movement cycle appropriate for the display apparatus, that the PLC may also preferably control. The adjustment assembly may suitably be associated with the drive assembly. The platen member may suitably be substantially rectangular in shape. The platen member may have a curved front face when viewed in section. The front face may be hemispherical or torispherical with a flat rear surface. The platen may suitably be manufactured from a plastic such as acrylic or polycarbonate or other transparent material, for example glass. The image mosaic is suitably mounted in stacked relation with, and suitably on, the platen, and the image mosaic may be shifted with the platen relative to an overlying screening mask for the purpose of selectively screening out certain portions of the mosaic to provide for projection through other portions thereof. Although it is preferable that the platen carry the image mosaic and move it relative to the mask, the platen could carry the mask and move it relative to the mosaic. The mosaic is likewise generally rectangular and includes a plurality of image pixels from a plurality of discrete images interspersed in a uniform pattern over the mosaic corresponding with the aperture pattern formed on the mask. Thus the mask may be placed over the mosaic and one of the two shifted relative to the other to register the apertures on the mask with the image pixels on the mosaic corresponding with one of the discrete images formed on the mosaic to display such image. Such relative shifting may be continued to sequentially register the apertures on the mask with the respective sets of pixels corresponding with the various discrete images interspersed on the mosaic. The mosaic will suitably be manufactured according to any one of a number of methods for the creation and display of multiple independent images from a mosaic of pixels which are interwoven in a predetermined arrangement such that each of the images can be selected by precise positioning of a screen in different positions relative to a grid mask which masks out all but pixels of a selected image are known, particularly in the field of advertising. The mosaic may be a plastic sheet member with the mosacied images printed thereon. The mosaic may be thin to enable the sheet to match the preferred curved shape of the front of the platen member. The mosaic is generally mounted in a closely spaced relationship with the platen and mask. The mosaic sheet may preferably include at least one alignment aperture therein. Suitably, the alignment aperture may be provided by a transparent section defined in an opaque region of the mosaic. For example, the opaque region may be provided at a lower portion of the mosaic sheet, outside the image mosaic. The transparent aperture may then be provided in the opaque region. More than one aligning aperture may be provided in the mosaic and the number and position of the aligning apertures will generally depend upon the degree of movement of the mosaic. The mask is generally rectangular and has an opaque grid work formed thereon defining a predetermined pattern of apertures spaced uniformly thereabout to block light from projecting through approximately 75% of the area of the mask. The blocking characteristics and the shape of the apertures will generally depend upon the number of images in the display and the content of the mosaic. The apertures are generally squares with sides of approximately 1mm in length, although this dimension and shape is changeable depending upon the size and configuration of the mosaic. The opaque mask preferably blocks back lighting from shining through the image mosaic except through the display apertures. The mask may be provided as a sheet member. The mask sheet may preferably also include at least one alignment aperture therein. Suitably, the alignment aperture may be provided by a transparent section defined in an opaque region of the mask. For example, the opaque region may be provided at a lower portion of the mask sheet, outside the grid provided for blocking the image mosaic. The transparent aperture may then be provided in the opaque region. More than one aligning aperture may be provided in the mask and the number and position of the aligning apertures will generally depend upon the movement of the mosaic. The aligning apertures of the mask and the mosaic are suitably offset from one another when the mask and the mosaic are correctly aligned with one another. The apertures are suitably rectangular in shape. The offset is suitably in the longitudinal dimension of the apertures. Most preferably, the respective aligning apertures are offset only to the degree that when as soon as the apertures cease to be longitudinally aligned with one another, no light will penetrate the respective opaque portions provided on the mosaic and mask and no light will pass these sections. This may allow the sensor to sense the position when the aligning apertures are no longer aligned and thus establish the correct alignment position. The drive means may include at least one linear actuator. Preferably the linear actuator includes a stepping function having an output shaft being operatively coupled to the mosaic or mask sheet. The stepping linear actuator is preferably coupled to the PLC so as to move the output shaft in opposing directions and effect reciprocating movement of the mask or the mosaic film. The PLC may be provided to selectively empower the drive means for predetermined distances to displace the mosaic relative to the mask a predetermined distance to register the image pixels of one of the discrete images on the mosaic with the apertures on the mask. Once such registration is achieved, the PLC may act to temporarily deactivate the drive means so that the image will be displayed for some preselected amount of time. After the preselected amount of time has elapsed, the PLC automatically empowers the drive means to again displace the mosaic to register the image portions corresponding with the next discrete image formed on the mosaic with the apertures on the mask. This sequence is continued to sequentially register the discrete images on the mosaic with the aperture pattern on the mask. The predetermined path for movement of the mosaic may suitably include an alignment phase, wherein the correct alignment of the mask and the mosaic is ensured, and a movement phase, in which predetermined movement steps of the mosaic relative to the mask are carried out to display each of the images of the mosaic. The alignment phase may form a part of the movement phase or be carried out at least partially contemporaneously with the movement phase. The alignment phase of the movement may include movement of the mosaic relative to the mask to establish the correct alignment position. The movement phase of the mosaic will generally be determined by the number and orientation of the various images in the mosaic. For example, if there are three images in the mosaic and they are offset from one another in vertically oriented strips, the movement is a linear (one dimensional) movement back and forth in the horizontal direction. With four image systems in which the images may be offset in a square pattern, two dimensional movement (horizontally and vertically) is generally required. More than one set of alignment apertures may be provided to align the mosaic and mask in both directions. According to a particularly preferred embodiment, the alignment procedure followed by the PLC in a 3-image display configuration may be as follows. Upon start-up of the apparatus or upon detecting a problem with the alignment of the mosaic and the mask, the infrared sensor will sense one of two states, namely: a) The sensor will detect light through the aligned respective apertures in the mask and the mosaic. The PLC is suitably programmed that upon detecting this situation, the PLC controls the drive means to move the image mosaic in a first direction. As the image is moved in the first direction, the size of the aligned apertures will typically become gradually smaller until the sensor detects no light, as the apertures will suitably no longer be corresponding. The PLC will suitably be programmed to treat this is the correct alignment position of the mask and the mosaic and the PLC will then follow the predetermined path of movement for the mosaic by moving the image a pre-programmed distance to the first direction to place the 2nd image into alignment with the apertures in the mask to allow its display. Then the PLC suitably counts the programmed number of steps back to the centre image to allow its display and following this it will count back further to the left image to allow its display. The PLC then advances the mosaic back to the correct alignment position whilst the sensor monitors the light through the aligned respective apertures in the mask and the mosaic. When the sensor stops detecting light through the aligned apertures, the PLC suitably takes this again as the correct alignment position and resets. Therefore, the position of the mosaic and the alignment of individual portions or pixels of the respective images with the mask may be checked in every cycle assuring correct alignment between the image mosaic and the mask. b) The sensor detects no light at the apertures in the mask and the mosaic, the PLC will move the image in a second direction until it detects light through the aligned apertures and from thereon, the PLC will suitably control the drive means to follow the alignment procedure described above in (a). In the instance of a 2-image display system or a 4-image display system, the routine or cycle may change slightly but the basic principle is identical. The housing generally includes a rear wall and a housing. The housing is generally rectangular and includes a number of peripheral side walls extending substantially perpendicularly from the rear wall, which is generally a planar plate. The rear wall is generally removably attached relative to the housing in order to provide access to the interior of the housing. Alternatively or additionally, one or more of the side walls of the housing may be removable. The housing mounts therein an illumination means generally including one or more spaced apart light tubes. There may also be one or more reflectors to enhance the illumination of the display apparatus. h a second form, the invention resides in a display apparatus for sequentially displaying sets of image pixels corresponding with discrete images interlaced on a transparent mosaic through an aperture pattern formed in a substantially opaque mask and including: i. a housing containing; a. a platen member having a plurality of mounting arms mounted thereon; and b. at least one platen support member, each at least one platen support member having a plurality of keyhole-shaped openings for mounting the platen member relative to the at least one platen support member, each opening having a larger cross-sectional area portion and a smaller cross-sectional slot portion, the number of openings corresponding to the number of mounting arms on the platen member, wherein at least some of the mounting arms are provided with at least one annular member, at least one of the annular members sized to be inserted through the larger cross-sectional area of the respective opening during mounting of the platen member and to retain the mounted platen member adjacent the at least one platen support member when the annular member is adjacent the slot. The smaller cross-sectional portion of the slot is suitably dimensioned to allow sufficient movement in all directions. The larger cross-sectional portion of the slot is suitably used only for fitment; it allows the annular members to be fitted through the keyhole-shaped opening before sliding the platen into position in the smaller cross-sectional slot. Suitably the annular member may be a polyethylene washer or the like. Suitably, the platen may be fixed in position in this way but may still be adapted to expand and contract due to thermal expansion and the like. Alternatively, the platen may be adapted to be moved by the drive means, thereby moving the associated mosaic. The platen support member or rail may extend substantially around the housing allowing the platen to be supported peripherally. The shaped openings may then all be oriented in the same direction. There may be more than one annular member associated with each opening, preferably a larger annular member and a smaller annular member with the larger annular member disposed between the platen member and the platen support member and the smaller annular member disposed behind the platen support member such that the wall of the platen support member is received between the annular members when the platen is fitted relative to the paten support member. One or both annular members may be manufactured of a low friction material and various types of plastics for example possess this quality. The mounting arms may include a machine screw or similar and the platen may have corresponding openings therein to receive the screws. The annular members may be removably attachable to the platen member. When fitting the platen member to the platen support member, the screws may be removed prior to fitting the larger annular member relative to the screw, the platen member may then be fitted into the keyhole-shaped openings and the smaller annular member may then be attached to the screw. Alternatively, the design of the mounting arms and the annular members may be such that the platen member may be fitted to the support rail when the annular members are already attached to the screws. In the past, the curved platen over which the mask and image mosaic are held has been mounted to the housing in a fixed position. With this embodiment of the invention, the platen may be easily removable, or if required replaceable, through the use of the keyhole-shaped openings. Another advantage of this aspect of the invention, is that the platen which is usually constructed of acrylic, polycarbonate or glass does not require a frame or further stiffening as the support rails hold it into position. In a third form, the invention resides in a display apparatus for sequentially displaying sets of image pixels corresponding with discrete images interlaced on a transparent mosaic through an aperture pattern formed in a substantially opaque mask and including: i. a platen member having a plurality of openings therein; ii. a plurality of elongate locating members; iii. a mosaic having a pair of side edges, a top edge and a bottom edge and a number of elongate openings corresponding to the number of locating members, at least one opening located adjacent each side edge and an opening adjacent either the top edge or the bottom edge of the mosaic, the openings adjacent the respective side edges oriented substantially parallel to the top or bottom edge of the mosaic and the openings adjacent the top or bottom edge oriented substantially parallel to the side edges of the mosaic. According to this aspect of the invention, the image mosaic may be maintained in relation to the platen member using up to 3 locating members. This suitably allows the platen member and the mosaic to expand and contract independently of one another. Another advantage is the simplicity of the mosaic replacement. As the mosaic replacement will be done each time it is desirable to change the advertisement to be displayed, it should be done as simply and quickly as possible. Each of the plurality of elongate locating members may suitably be a peg or pin, each of which may be removable or fixed. The pins may suitably be cylindrical and have a radial dimension. The openings in the platen may preferably receive the locating pins closely in order to secure the pins therein. The members will suitably be long enough to be received into the openings in the platen member and extend outwardly to support the mosaic adjacent the platen member. The members may be fitted into the openings and then the mosaic fitted subsequently or the openings in the mosaic may be aligned with the openings in the platen and the locating members fitted through both. The mosaic has a pair of side edges, a top edge and a bottom edge and a number of elongate openings corresponding to the number of locating members, at least one opening located adjacent each side edge and an opening adjacent either the top edge or the bottom edge of the mosaic, the openings adjacent the respective side edges oriented substantially parallel to the top or bottom edge of the mosaic and the openings adjacent the top or bottom edge oriented substantially parallel to the side edges of the mosaic. There will generally be 3 openings, one adjacent the bottom edge of the mosaic and one adjacent either side edge. The openings in the mosaic are suitably elongate openings which have a longitudinal and a transverse dimension. Suitably the openings may be oriented according to their longitudinal dimension. The longitudinal dimension of the openings is preferably greater than the radial dimension of the pins, usually be at least a factor of 2. The transverse dimension of the openings may be only slightly larger than the radial dimension of the pins to assist in the minimisation of misalignment of the mosaic. To replace the image the 3 location pins may be removed, the image is slid out from behind the mask, new image is slid back into place, location pins are replaced and the unit is started. The optical alignment system as discussed previously may then take over to bring the mosaic into the correct alignment with the mask. In a fourth form, the invention resides in a display apparatus for sequentially displaying sets of image pixels corresponding with discrete images interlaced on a transparent mosaic through an aperture pattern formed in a substantially opaque mask and including: i. a housing; ii. the mask having a pair of side edges, a top edge and a bottom edge and at least two columns of spaced apart apertures, one column located adjacent either side edge of the mosaic; and iii. mask mounting means mounted relative to the housing, the mask mounting means including a plurality of resilient teeth members extending therefrom to engage the apertures of the mask and retain the mask under tension, at least some of the tooth members located towards a central portion of the mounting means sized to be closely received in the corresponding apertures to positively locate the central portion of the mask, and at least some of the tooth members located towards an outer portion of the mounting means sized to be loosely received in the corresponding apertures to allow expansion and contraction of the mosaic or the mounting means. According to this aspect of the invention, the mask may be further provided with a pair of columns of spaced apart bores formed adjacent the opposite longitudinal ends of the mask, such bores defining mounting bores for releasably mounting the mask in relation to the housing. As discussed previously, it can be very important that the mosaic film and the mask are in intimate contact with each other. In the past this has been achieved by fitting a stainless steel strip to the ends of the mask by way of adhesives in order to hold the mask flat and in position in relation to the platen and image mosaic. As the mask is a component with a finite life this can be an expensive proposition. According to this aspect of the present invention, the mask may be held in position by a pair of profile cut spring combs. Suitably, each side of the mask will be provided with a comb, the comb on one side of the mask capable of flexing and the other, preferably fixed. This will assist to maintain the location and orientation of the mask. The mask mounting means of the present invention preferably includes a plurality of resilient teeth members extending from the mask mounting means to engage the apertures of the mask and retain the mask under tension. The teeth members may be provided integrally with the mask mounting means or the teeth may be removable from the mounting means or separately from the mask mounting means altogether. As would be appreciated, different sized display apparatus may be manufactured. One simple way to manufacture these different sizes of apparatus easily is to manufacture an extruded strip of mounting means of indefinite length and then cut the mounting means into the required length for a particular apparatus. By having the teeth separate from but insertable into the mounting means, the length of the mounting means can be changed, as can the numbers and configurations of the centrally located teeth and the outer teeth. hi practice for larger dimension displays it would be difficult to fold an accurate comb spring longer than approximately 600 mm. Therefore, a short mask mounting means will suitably be used at the centre of the mask. This mask mounting means may then assisted by a number of individual mounting members spaced over the remaining height of the apparatus to tension the mask over the platen to its extremities. At the opposite side of the mask the mask mounting means may again be assisted by an equal number of separate mounting members. This setup may allow the mask film to expand and contract as required due to temperature and humidity but importantly will not allow it to skew in its position. The provision of at least some of the tooth members located towards a central portion of the mounting means being sized to be closely received in the corresponding apertures to positively locate the central portion of the mask, and at least some of the tooth members located towards an outer portion of the mounting means being sized to be loosely received in the corresponding apertures to allow expansion and contraction of the mosaic or the mounting means is designed to allow the image and/or the platen to expand or contact without moving the centre of the image. The length of the teeth may also be adaptable in order to adjust the amount of tension to be placed on the mask. The shape of the teeth may include a portion which is "bent" towards the centre of the mask in order to assist with the positioning of the mask in the housing. In a fifth form, the invention resides in a display apparatus for sequentially displaying sets of image pixels corresponding with discrete images interlaced on a transparent mosaic through an aperture pattern formed in a substantially opaque mask and including: i. a housing containing; a. a platen member having two side edges, a top edge and a bottom edge; b. a platen mounting means including i. an L-shaped member mounted relative to each side edge of the platen member; ii. a support bracket mounted relative to the housing; iii. a support extension extending upwardly from the support bracket, and substantially co-axial with the L-shaped member; and iv. a reduced friction assembly between the support extension and the L-shaped member to enhance sliding movement between the support extension and the L-shaped member. When the image display unit is constructed as a 2-image or 3-image unit, it is important that the image mosaic and mask remain aligned along the horizontal as the drive means drives the platen through the predetermined path. In the past an elaborate mechanism with mechanical arms has been used to achieve this. An added problem is that initial adjustment is required to align the mask and the image mosaic along the horizontal centre of the image and mask. According to an aspect of the present invention, a simple spring clip can be used to achieve the above. The platen mounting means may be or included that similar to that described above. There will generally be a platen support means at either side of the platen located approximately half way up the height of the housing although other positions are anticipated. According to this aspect of the invention, the platen mounting means may include an L-shaped member mounted relative to each side edge of the platen member. An L-shaped member will generally be mounted at the edge of each side of the platen member and any mounting means can be used. The L-shaped member will generally have two arm members oriented substantially perpendicularly to each other and one of the arms will be abut the platen member leaving the other arm member extending substantially perpendicularly from the platen. The L-shaped member is suitably manufactured of plastic or metal for example. The platen mounting means will typically also include a support bracket mounted relative to the housing. The support bracket will suitably be mounted towards rear of the housing and extend toward towards the front of the housing, terminating in a free end. The support bracket may be spaced from the protruding arm of the L-shaped member. The bracket may also include a portion extending from adjacent the free end of the bracket. This portion may be perpendicular to the bracket and may be adapted to be a guide means for the movement of the platen member. The platen mounting means may also include a support extension extending upwardly from the support bracket, and substantially co-axial with the L- shaped member. This extension will generally be a part of an adjustment member which extends from adjacent the bottom of the housing, upwardly to the mounting means. The adjustment member may suitably be a rod which extends through a corresponding threaded opening in the support bracket. The rod will typically have at least a threaded portion such that rotation of the rod will increase or decrease the height of the rod which extends upwardly from the support bracket. This may allow the vertical position of the platen member. The reduced friction assembly between the support extension and the

L-shaped member to enhance sliding movement between the support extension and the L-shaped member will suitably include a reduced friction member associated with the arm of the L-shaped member. There may also be a resilient member associated with the support bracket and extending between the support extension and the L- shaped member. The resilient member will suitably be arcuate when viewed in side elevation and may extend inwardly laterally. The curved shape of the resilient member may adapt the resilient member to enhance the sliding movement of the platen member. The platen member may thereby free to move as directed by the driving motor along the horizontal with a minimum amount of friction and mask and mosaic will remain parallel once adjusted. The support means may be provided with roller bearings when the weight of the platen increases along with the size of the unit and the platen. It is to be appreciated that for a 4-image unit, the platen mounting means may instead include a plurality of linear actuators also responsible for the movement of the platen. The linear actuators may be located adjacent the top of the unit with a shaft extending downwards. The shaft may flex to accommodate the sideway movement of the platen. For larger 4-image display units, rather than having the platen fixed along the horizontal position, it may be adapted to move in a vertical plane as well due its attachment to 2 further drive means, each preferably linear actuators. Each linear actuator is suitably attached by a long flexible shaft to a platen attachment bracket which is in turn preferably attached to the platen. In operation, the horizontal linear actuator can suitably move the platen in the horizontal plane and the combination of the left hand vertical linear actuator and the right hand vertical linear actuator can move the platen in the vertical plane. The flexible shafts may allow the movement of the platen in both planes independently. The majority of the weight of the platen may be carried by a resilient member, typically a spring attached on one end to the platen attachment bracket and on the other end to a fixed point in the display unit, generally to the housing. This may allows for a much less powerful linear actuator to be used to obtain the platen displacement required. hi a sixth form, the invention resides in a display apparatus for sequentially displaying sets of image pixels corresponding with discrete images interlaced on a transparent mosaic through an aperture pattern formed in a substantially opaque mask and including: a housing containing; a. a platen member; and b. illumination components for illuminating the mosaic, the components mounted relative to a slideable member which is removable from the housing without disturbing the platen member, mosaic or mask. In the field, maintenance of the unit has to be performed in a most cost- effective manner. Apart from breakdown of a component, the illumination means is generally the most critical wearing component in the unit. Due to the mounting of the mask, image mosaic and platen combination, it is difficult to perform maintenance or replacement of apparatus components conventionally through the front of the apparatus. In the past, hinge systems have been used to split the housing into two or more parts so as to give access to the lamps and illumination controls. This difficulty may be overcome in the current invention by mounting the illumination components of the apparatus on a slideable member which is removable from the housing without disturbing the platen member, mosaic or mask According to the most preferred embodiment, the slideable member may be a slide out tray. Preferably, as the tray is slid out of the housing, a plug and socket power supply system the plug portion of which may be attached to the housing and the socket portion of which may be attached to the tray, may disconnect the power to the illumination means. So replacing blown bulbs or fluorescent tubes or any illumination component attached to the tray is now a quick proposition. Any one or more of the above aspects can be combined into a single display apparatus and a display apparatus combining all of the aspects is particularly preferred. Brief Description of the Drawings. Various embodiments of the invention will be described with reference to the following drawings, in which: Figure 1 is a perspective exploded view of an apertured mask is positioned relative to an image mask. In an assembled condition, the mask and the mosaic will be in intimate contact with each other but are illustrated in an exploded condition for clarity. Figure 2 is a front view of the mask overlaying the image mosaic in the correct alignment according to a preferred embodiment of an aspect of the present invention. Figure 3 is a front view of the mask overlaying the image mosaic in an incorrect alignment showing aligned apertures according to a preferred embodiment of an aspect of the present invention. Figure 4 is a perspective view of the platen in the mounted position on the platen support rail according to a preferred embodiment of an aspect of the present invention. Figure 5 is a reverse perspective view of the platen illustrated in Figure

4. Figure 6 is a schematic view of the mosaic mounted relative to the platen and the locating pins according to a preferred embodiment of an aspect of the present invention. Figure 7 is a perspective view of a mask mounting comb according to a preferred embodiment of an aspect of the present invention. Figure 8 is a detail front view of the platen mounting assembly according to a preferred embodiment of an aspect of the present invention. Figure 9 is a detail perspective view of the platen mounting assembly according to a preferred embodiment of an aspect of the present invention. Figure 10 is perspective view of a partially removed sliding tray according to a preferred embodiment of an aspect of the present invention. Figure 11 is perspective view of a mask mounting means for large dimension display units according to a preferred embodiment of an aspect of the present invention. Figure 12 is perspective view of a platen support assembly for a 4- image display unit according to a preferred embodiment of an aspect of the present invention. Figure 13 is perspective view of the detailed area of Figure 12. Detailed Description of the Invention. According to a preferred embodiment of an aspect of the present invention, a multi-image display apparatus is provided. A preferred embodiment of the first aspect of the invention may be better understood with reference to figures 1 to 3: The display apparatus of this embodiment sequentially displays sets of image portions corresponding with discrete images interlaced on a transparent mosaic 10 through an aperture pattern formed in a substantially opaque mask 11 and including: a housing containing a. a platen member, b. at least one platen mount, c. a mask holder assembly for releasably mounting said mask thereon; d. at least one adjustment assembly for, upon adjustment thereof, adjusting the position of said mosaic relative to said opaque mask; and e. a drive assembly including a mounting assembly for mounting said mosaic relative thereto and operative to drive said mosaic in a predetermined path corresponding with said aperture pattern, said adjustment device adapted to adjust the positioning of said mosaic relative to said opaque mask by following a predetermined path to selectively align corresponding portion of said images with the respective said apertures. The elements of the display apparatus apart from the mosaic 10 and mask 11 are not shown in figures 1 to 3. Generally, after properly aligning the mosaic 10 with the mask 11 and operating the apparatus for some time, the mask and mosaic may become slightly misaligned. This will cause the apertures of the mask to be aligned with image portions corresponding with multiple images rather than with the portions of only one image, causing the device to display a blurred double image as seen in figure 2. The adjustment assembly of the preferred embodiment is an optical alignment system and includes one infrared sensor (not shown) for a 2 or 3-image display apparatus (horizontal or vertical movement only or single dimension movement) and 3 sensors for a 4-image display (horizontal and vertical movement or two dimensional movement). The infrared sensor is mounted in a fixed position relative to the mosaic 10 and/or mask 11. The predetermined path is controlled by a programmable logic controller (PLC). The PLC controls the movement of the mosaic 10 or platen relative to the mask 11 to align the image correctly with respect to the aperture pattern in the mask at the starting point of a movement cycle appropriate for the display apparatus, The PLC also controls the movement pattern itself. The adjustment assembly is therefore associated with the drive assembly. The platen member of the invention is substantially rectangular in shape and has a curved front face when viewed in section with a flat rear surface. The platen will generally be manufactured from a plastic such as acrylic, polycarbonate or glass. The image mosaic 10 is mounted on the platen, and the image mosaic

10 is shifted with the platen relative to the overlying screening mask 10 for the purpose of selectively screening out certain portions of the mosaic 10 to provide for projection through other portions thereof. The platen is generally the element which is moved and the mosaic 10 moves in sympathy with the platen. The mosaic 10 is also generally rectangular and includes a plurality of image pixels (seen in Figure 1) from a plurality of discrete images interspersed in a uniform pattern over the mosaic 10 corresponding with the aperture pattern formed on the mask 11. Thus, the mask 11 is placed over the mosaic 10 and one of the two shifted relative to the other to register the apertures on the mask 11 with the image portions on the mosaic 10 corresponding with one of the discrete images formed on the mosaic 10 to display such image. Such relative shifting is continued to sequentially register the apertures on the mask 11 with the respective sets of portions corresponding with the various discrete images interspersed on the mosaic 10. The mosaic 10 is a plastic sheet member with the mosacied images printed thereon. The mosaic 10 is thin to enable the sheet to match the curved shape of the front of the platen member. As seen in Figure 1, the mosaic sheet 10 includes an alignment aperture

12 therein. The alignment aperture 12 is provided as a transparent section defined in an opaque region of the mosaic 10 which surrounds the mosaiced images. The opaque region is provided at a lower portion of the mosaic sheet 10, outside the image mosaic itself. The mask 11 is also generally rectangular and has an opaque grid work formed thereon defining a predetermined pattern of apertures spaced uniformly thereabout to block light from projecting through approximately 75% of the area of the mask 11. The blocking characteristics and the shape of the apertures will depend upon the number of images in the display and the content of the mosaic 10. The apertures of figure 1 are squares with sides of approximately 1mm in length, although this dimension and shape is changeable depending upon the size and configuration of the mosaic 10. The mask 11 blocks back lighting from shining through the image mosaic 10 except through the display apertures. The mask 11 is provided as a sheet member. The mask sheet 11 also includes at least one alignment aperture 13 therein. Again, the alignment aperture 13 is provided as a transparent section defined in an opaque region of the mask 11. The aligning apertures 12, 13 of the mask 11 and the mosaic 10 are offset from one another when the mask 11 and the mosaic 10 are correctly aligned with one another as seen in figure 2. The alignment apertures 12, 13 are rectangular in shape. The offset in the longitudinal dimension of the apertures 12, 13. The respective aligning apertures 12, 13 are offset only to the degree that when as soon as the apertures 12, 13 cease to be longitudinally aligned with one another, no light will penetrate the respective opaque portions provided on the mosaic 10 and mask 11 and no light will pass these sections. This will allow the sensor to sense the position when the aligning apertures 12, 13 are no longer aligned and thus establish the correct alignment position. The drive means includes at least one linear actuator. The linear actuator includes a stepping function having an output shaft being operatively coupled to the mosaic or mask sheet by means of a slide member which may suitably be guided by a sleeve or track. The stepping linear actuator is coupled to the PLC so as to move the output shaft in opposing directions and effect reciprocating movement of the slide member which is operatively coupled to the mask 11 or the mosaic 10 sheets. The PLC selectively empowers the actuator to displace the mosaic 10 relative to the mask 11 a predetermined distance to register the image portions of one of the discrete images on the mosaic 10 with the apertures on the mask 11. Once such registration is achieved, the PLC acts to temporarily deactivate the drive means so that the image will be displayed for some preselected amount of time. After the preselected amount of time has elapsed, the PLC automatically empowers the drive means to again displace the mosaic 10 to register the image portions corresponding with the next discrete image formed on the mosaic 10 with the apertures on the mask 11. This sequence is continued to sequentially register the discrete images on the mosaic 10 with the aperture pattern on the mask 11. The predetermined path for movement of the mosaic 10 includes an alignment phase, wherein the correct alignment of the mask 11 and the mosaic 10 is ensured, and a movement phase, in which predetermined movement steps of the mosaic 10 relative to the mask 11 are carried out to display each of the images of the mosaic 10. The alignment phase generally forms a part of the movement phase. The alignment phase of the movement includes movement of the mosaic 10 relative to the mask 11 to establish the correct alignment position. The movement phase of the mosaic 10 is determined according to the number and orientation of the various images in the mosaic 10. For example, if there are three images in the mosaic 10 and they are offset from one another in vertically oriented strips, the movement is a linear (one dimensional) movement back and forth in the horizontal direction. With four image systems in which the images may be offset in a square pattern, two dimensional movement (horizontally and vertically) is required. More than one set of alignment apertures may be provided to align the mosaic 10 and mask 11 in both directions. According to the preferred embodiment, the alignment procedure followed by the PLC in a 3-image display configuration is as follows. Upon start-up of the apparatus or upon detecting a problem with the alignment of the mosaic 10 and the mask 11, the infrared sensor will sense one of two states, namely: a) The sensor will detect light through the aligned respective apertures 12, 13 in the mask 11 and the mosaic 10. The PLC is programmed that upon detecting this situation, the PLC controls the drive means to move the image mosaic 10 in a first direction. As the image is moved in the first direction, the size of the aligned apertures 12, 13 will become gradually smaller until the sensor detects no light, as the apertures will suitably no longer be corresponding. The PLC will suitably be programmed to treat this is the correct alignment position of the mask 11 and the mosaic 10 and the PLC will then follow the predetermined path of movement for the mosaic 10 by moving the image a pre-programmed distance to the first direction to place the 2nd image into alignment with the apertures in the mask 11 to allow its display. Then the PLC suitably counts the programmed number of steps back to the centre image to allow its display and following this it will count back further to the left image to allow its display. The PLC then advances the mosaic 10 back to the correct alignment position whilst the sensor monitors the light through the aligned respective apertures 12, 13 in the mask 11 and the mosaic 10. When the sensor stops detecting light through the aligned apertures, the PLC suitably takes this again as the correct alignment position and resets. Therefore, the position of the mosaic 10 and the alignment of individual portions of the respective images with the mask 11 may be checked in every cycle assuring correct alignment between the image mosaic 10 and the mask 11. b) The sensor detects no light at the apertures in the mask 11 and the mosaic 10, the PLC will move the image in a second direction until it detects light through the aligned apertures and from thereon, the PLC will control the drive means to follow the alignment procedure described above in (a). In the instance of a 2-image display system or a 4-image display system, the routine or cycle may change slightly but the basic principle is identical. A preferred embodiment of the second aspect of the invention may be better understood with reference to figures 4 and 5: Figure 4 shows the platen 14 in the operating position. Figure 5 is a view from the rear of the platen 14. A platen support rail 15 has a number of keyhole shaped openings 16 around the perimeter of the platen 14. Each keyhole-shaped opening 16 has a smaller cross-sectional portion 20 of the opening is dimensioned to allow sufficient movement in all directions and a larger cross-sectional portion 21 of the opening 16 is suitably used only for fitment; it allows the annular member 19 to be fitted through the keyhole-shaped opening 16 before sliding the platen 14 into position in the smaller cross-sectional portion 20. hi the platen 14 are machine screws 17 fitted prior to assembly in the same pattern as the keyhole shaped openings 16 in the support rail 15. The platen 14 is spaced from the support rail 15 by a larger low friction washer 18 mounted on the machine screw 17. When fitting the platen 14, a smaller diameter, rear low friction washer 19, also fitted on the machine screw 17 will fit through the larger cross-section portion 21 of the keyhole-shaped opening 16. The platen 14 is then slid into place to the right and the drive motor or motors are attached holding the platen 14 into position. The motors will be able to move the platen 14 left and right (limited by the length of the smaller cross-sectional portion 20 of the opening 16) as well as up and down (limited by the height of the smaller cross-sectional portion 20 of the opening 16) as required to obtain alignment of the mask 11 and image mosaic 10. The annular members are each a polyethylene washer or the like. The platen 14 may be fixed in position in this way but may still be adapted to expand and contract due to thermal expansion and the like. A preferred embodiment of the third aspect of the invention may be better understood with reference to figure 6: Figure 6 shows the mosaic 10 overlaying the platen 14. hi the platen 14 are 3 openings 22 into which a location pin 23 is inserted, h the mosaic 10, are 3 corresponding elongate openings 24. The mosaic 10 has a pair of side edges, a top edge and a bottom edge and a number of elongate openings 24 corresponding to the number of locating pins 23. There is an opening located adjacent each side edge and an opening adjacent the bottom edge of the mosaic 10. The elongate openings 24 adjacent the respective side edges are oriented substantially parallel to the top or bottom edge of the mosaic 10 and the elongate openings 24 adjacent the top or bottom edge are oriented substantially parallel to the side edges of the mosaic 10. The elongate openings 24 are oriented according to their longitudinal dimension. The longitudinal dimension of the openings is greater than the radial dimension of the pins 23. The transverse dimension of the elongate openings 24 is only slightly larger than the radial dimension of the pins 23 to assist in the minimisation of misalignment of the mosaic 10. To replace the mosaic 10, the 3 location pins 23 are removed, the mosaic is slid out from behind the mask 11, new mosaic 10 is slid back into place, location pins 23 are replaced and the unit is started. The optical alignment system as discussed previously will then take over to bring the mosaic 10 into the correct alignment with the mask 11. For larger units, the pins are generally fixed in the openings in the platen 14. This allows the mosaic 10 to expand and contract in any direction without moving its all important centre position 25. The platen 14 can also expand or contract on any direction without putting strain on the mosaic 10 or upsetting its location. A preferred embodiment the fourth aspect of the invention may be better understood with reference to figures 7 and 11 : The mask 11 is further provided with a pair of columns of spaced apart bores 26 formed adjacent the opposite longitudinal ends of the mask 11, such bores 26 defining mounting bores for releasably mounting the mask 11 in relation to the housing. The comb provided on one side of the mask is fixed and the other has flexible teeth. The mask mounting means of the preferred embodiment is a mask comb 28 includes a plurality of resilient teeth members 27 extending from the comb 28 to engage the bores 26 of the mask 11 and retain the mask 11 under tension. The teeth members 27 may be provided integrally with the comb 28 or the teeth 27 may be removable from the comb 28 or provided separately therefrom altogether. As would be appreciated, different sized display apparatus may be manufactured. One simple way to manufacture these different sizes of apparatus easily is to manufacture an extruded strip of comb 28 of indefinite length and then cut the comb 28 into the required length for a particular apparatus. By providing teeth separate from the comb 28, the effective length of the comb 28 can be changed, as can the numbers and configurations of the centrally located teeth and the outer teeth. The provision of at least some of the tooth members located towards a central portion of the comb 28 being sized to be closely received in the corresponding apertures to positively locate the central portion of the mask 11, and at least some of the tooth members located towards an outer portion of the comb being sized to be loosely received in the corresponding apertures to allow expansion and contraction of the mosaic 11 or the comb 28 is designed to allow the mask 11 and/or the platen 14 to expand or contact without moving the centre of the mosaic 10. The length of the teeth 27 is also adaptable in order to adjust the amount of tension to be placed on the mask 11. The shape of the teeth may include a portion which is "bent" or folded towards the centre of the mask 11 in order to assist with the positioning of the mask 1 lin the housing. In practice, for larger dimension displays it would be difficult to fold an accurate comb spring longer than approximately 600 mm. Therefore, a short comb spring 28 can be used at the centre of the mask 11. This comb 28 is then assisted by the provision of a number of individual teeth 27 to tension the mask 11 over the platen 14 to its extremities. At the opposite side of the mask 11, the fixed comb 28 would again be assisted by an equal number of separate teeth 27. This setup will allow the mask film to expand and contract as required due to temperature and humidity and importantly will not allow it to skew in its position. The setup for larger displays is illustrated in Figure 11. The fifth aspect of the invention may be better understood with reference to figures 8 and 9: Figures 8 and 9 show a detail section from the left horizontal centre portion of the platen 14 showing the platen mounting means for a 2 or 3 image display unit. Attached to the platen 14 is an L-shaped piece of steel angle 29 with a low friction, low wear plastic foot 30 attached thereto. The plastic foot 30 rests on a thin stainless spring section 31, which is fastened at its flat end to a platen support bracket 32. Attached to the support bracket 32 is a threaded nut 33. Winding an adjuster rod 34 up and down will raise or lower the spring section 31 which in turn supports the platen 14 via the foot 30. Figures 12 and 13 shows the preferred embodiment of the platen for a 4 image unit. Rather than having the platen fixed along the horizontal position, it is now free to move in a vertical plane as well due its attachment to 2 further linear actuators. The figures show the left side of a landscape-based display. In particular, the left hand vertical drive linear actuator 35 is illustrated. The linear actuator 35 is attached by a long flexible shaft 36 to a platen attachment bracket 37 which is in turn attached to the removable platen 14. In operation, the horizontal linear actuator 38 can move the platen 14 in the horizontal plane and the combination of the left hand vertical linear actuator 35 and the right hand movement assembly 39 can move the platen 14 in the vertical plane. The respective flexible shafts 36 attached to the actuators allow movement of the platen 14 in both planes independently. The majority of the weight of the platen is carried by a spring 40 attached on one end to the platen attachment bracket 37 and on the other end to a fixed point in the display unit, generally the housing. This in turn allows for much less powerful linear actuators to be used to obtain the platen displacement required. A preferred embodiment of the sixth aspect of the invention may be better understood with reference to figure 10: Figure 10 shows how the illumination component tray 41 is lifted in this case as per arrow 42 from the top of the housing 43. The platen 14 and mosaic 10 of the unit need not be disturbed. As the tray 41 is slid out of the housing 43, a plug and socket power supply system (not shown), the plug portion of which may be attached to the housing and the socket portion of which may be attached to the tray, disconnects the power to the bulbs. In the present specification and claims, the word "comprising" and its derivatives including "comprises" and "comprise" include each of the stated integers but does not exclude the inclusion of one or more further integers. Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations.

Claims

1. A display apparatus for sequentially displaying sets of image portions corresponding with discrete images interlaced on a transparent mosaic through an aperture pattern formed in a substantially opaque mask and including: a housing containing a. a platen member, b. at least one platen mount, c. a mask holder assembly for releasably mounting said mask thereon; d. at least one adjustment assembly for, upon adjustment thereof, adjusting the position of said mosaic relative to said opaque mask; and e. a drive assembly including a mounting assembly for mounting said mosaic relative thereto and operative to drive said mosaic in a predetermined path corresponding with said aperture pattern, said adjustment assembly adapted to adjust the positioning of said mosaic relative to said opaque mask by following a predetermined path to selectively align corresponding components of said images with the respective said apertures.

2. A display apparatus according to claim 1 wherein the adjustment assembly is an optical alignment system and includes at least one sensor, and a programmable logic controller (PLC) associated with the drive assembly to adjust the position of the mosaic.

3. A display apparatus according to claim 2 wherein the mosaic and the mask each include at least one alignment aperture therein, the aligning apertures of the mask and the mosaic being at least partially aligned with one another when the mask and the mosaic are incorrectly aligned with one another, the predetermined path for movement of the mosaic including an alignment phase, wherein the correct alignment of the mask and the mosaic is ensured, and a movement phase, in which predetermined movement steps of the mosaic relative to the mask are carried out to display each of the images of the mosaic, the alignment phase of the movement including movement of the mosaic relative to the mask to establish the correct alignment position. 4. A display apparatus according to claim 2 wherein the alignment procedure followed by the PLC in a 3-image display configuration has the following steps: a) the sensor detects light through the aligned respective apertures in the mask and the mosaic; b) the PLC controls the drive means to move the mosaic in a first direction; c) as the image is moved in the first direction, the size of the aligned apertures becomes gradually smaller until the sensor detects no light; the PLC treating this is the correct alignment position of the mask and the mosaic and the PLC will then follow the predetermined path of movement for the mosaic.

5. A display apparatus for sequentially displaying sets of image pixels corresponding with discrete images interlaced on a transparent mosaic through an aperture pattern formed in a substantially opaque mask and including: a housing containing; a. a platen member having a plurality of mounting arms mounted thereon; and b. at least one platen support member, each at least one platen support member having a plurahty of keyhole-shaped openings for mounting the platen member relative to the at least one platen support member, each opening having a larger cross-sectional area portion and a smaller cross- sectional slot portion, the number of openings corresponding to the number of mounting arms on the platen member, wherein at least some of the mounting arms are provided with at least one annular member, at least one of the annular members sized to be inserted through the larger cross-sectional area of the respective opening during mounting of the platen member and to retain the mounted platen member adjacent the at least one platen support member when the annular member is adjacent the slot.

6. A display apparatus for sequentially displaying sets of image pixels corresponding with discrete images interlaced on a transparent mosaic through an aperture pattern formed in a substantially opaque mask and including: i. a platen member having a plurality of openings therein; ii. a plurality of elongate locating members; iii. a mosaic having a pair of side edges, a top edge and a bottom edge and a number of elongate openings corresponding to the number of locating members, at least one opening located adjacent each side edge and an opening adjacent either the top edge or the bottom edge of the mosaic, the openings adjacent the respective side edges oriented substantially parallel to the top or bottom edge of the mosaic and the openings adjacent the top or bottom edge oriented substantially parallel to the side edges of the mosaic. 7. A display apparatus for sequentially displaying sets of image pixels corresponding with discrete images interlaced on a transparent mosaic through an aperture pattern formed in a substantially opaque mask and including: i. a housing; ii. the mask having a pair of side edges, a top edge and a bottom edge and at least two columns of spaced apart apertures, one column located adjacent either side edge of the mosaic; and iii. mask mounting means mounted relative to the housing, the mask mounting means including a plurality of resilient teeth members extending therefrom to engage the apertures of the mask and retain the mask under tension, at least some of the tooth members located towards a central portion of the mounting means sized to be closely received in the corresponding apertures to positively locate the central portion of the mask, and at least some of the tooth members located towards an outer portion of the mounting means sized to be loosely received in the corresponding apertures to allow expansion and contraction of the mosaic or the mounting means. 9. A display apparatus for sequentially displaying sets of image pixels corresponding with discrete images interlaced on a transparent mosaic through an aperture pattern formed in a substantially opaque mask and including: a housing containing; a. a platen member having two side edges, a top edge and a bottom edge; b. a platen mounting means including i. an L-shaped member mounted relative to each side edge of the platen member; ii. a support bracket mounted relative to the housing; iii. a support extension extending upwardly from the support bracket, and substantially co-axial with the L-shaped member; and iv. a reduced friction assembly between the support extension and the L-shaped member to enhance sliding movement between the support extension and the L-shaped member.

9. A display apparatus for sequentially displaying sets of image pixels corresponding with discrete images interlaced on a transparent mosaic through an aperture pattern formed in a substantially opaque mask and including: a. a housing containing; b. a platen member; and illumination components for illuminating the mosaic, the components mounted relative to a slideable member which is removable from the housing without disturbing the platen member, mosaic or mask.

10. A display apparatus for sequentially displaying sets of image pixels corresponding with discrete images interlaced on a transparent mosaic through an aperture pattern formed in a substantially opaque mask and including: a housing containing; a. a platen member having two side edges, a top edge and a bottom edge; b. a platen mounting means including i. a platen mounting member mounted relative to each side edge of the platen member; ii. a support bracket mounted relative to the housing; and iii. a resilient member extending between the platen mounting member and the platen support member to support at least part of the weight of the platen member.