US3296431A - Illuminated display fixture - Google Patents

Description

Jan. 3, 1967 F. L. GREENv ILLUMINATED DISPLAY FIXTURE Filed July 28, 1964 INVENTOR. ,lwfA/c ff 61am/ vBY @wauw ATT NEYS United States Patent O 3,296,431 ILLUMINATED DISPLAY FXTURE Frederic Lee Green, El Cerrito, Calif., assignor to Prescolite Manufacturing Corporation, San Leandro, Calif., a corporation of California Filed July 28, 1964, Ser. No. 385,651 '7 Claims. (Cl. 240-1L2) This invention relates generally to lighting fixtures, and more particularly is directed to fixtures wherein light from an illumination source passes through a diffusing panel, or similar member.

When a relatively localized illumination source, such as an incandescent or fluorescent bulb, is positioned for transmitting light through a diffusing panel of relatively large area, it will be appreciated that those portions of the panel disposed closer to the bulb will be illuminated with greater intensity than more remote portions of the panel. Consequently, when the panel is viewed there is presented a non-uniform light distribution throughout the panels area, and it is possible to observe an outline of the bulb itself in the region of most intense panel illumination. This non-uniformity becomes very significant in instances where the source must be positioned closely adjacent to the panel, since those portions of the panel immediately adjacent the bulb are illuminated much more intensely than other panel portions spaced only a slight distance away.

In providing certain types of display lighting fixtures, as for example exit signs used in public buildings, it is desirable that the fixture have a relatively thin cross section in order to make it unobtrusive and to avoid a cumbersome bulky design. Consequently, the light source enclosed within a housing of a fixture of this type must necessarily be disposed closely adjacent the display panels to be illuminated. From a standpoint of manufacturing and cost considerations, it has been found generally impractical to utilize a sufficient number of individual sources to provide the desired uniform field of illumination of the display panel. Thus, in many instances prior devices of this type have utilized only a small number of sources which resulted in a non-uniform lighting effect such as that described above.

Accordingly, one object of the present invention is to provide a lighting fixture having a relatively localized lighting source disposed adjacent a relatively large area diffusing panel wherein means is provided to improve the uniformity of illumination of all portions of the panel.

Another object of the invention is to provide a lighting fixture having a relatively thin cross section wherein a relatively localized lighting source is disposed closely adjacent a relatively large area display panel, and wherein means is provided to minimize the localized intensity of illumination of panel portions closely adjacent the source and to increase the intensity of illumination of panel portions relatively remote from the source thereby improving the overall uniformity of illumination of the panel.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the following description of the preferred form of the invention which is illustrated in the drawings accompanying and forming part of the specification. It is to be understood, however, that variations in the showing made by the said drawings and description may be adopted within the scope of the invention as set forth in the claims.

Referring to said drawings:

FIGURE l is a front elevation view of a lighting fixture embodying the present invention.

FIGURE 2 is a cross sectional side elevation view taken along the line 2-2 as shown in FIGURE l.

FIGURE 3 is a front elevation view similar to FIG- ICC URE l, but with the front of the fixture open to reveal its interior.

FIGURE 4 is a front elevation view of a light diffusing panel utilized in a lighting fixture in accordance with the present invention.

FIGURE 5 is an enlarged fragmentary cross sectional view taken generally along the line S-S as shown in FIGURE 4.

A preferred embodiment of the invention is illustrated in the drawings, and is seen to comprise a display lighting fixture 11 having a housing 12 and a display panel 13 depicting the word EXIT. In general, the housing 12 has a pair of closely spaced walls 14 and 16, with a plurality of incandescent light bulbs 17 comprising illumination means disposed intermediate the walls. As shown, the wall 16 has cutout openings 18 therein to define the word EXITJ A diffusing panel 19 overlies the reverse side of the wall 16 and has raised portions 21 respectively defining the letters of the word EXIT which extend outwardly through the openings 18 in the wall 16. The diffusing panel 21 is made of a suitable light transmitting material and may be formed with an appropriate color pigmentation.

It will be appreciated that the structure as described thus far can be utilized to provide an illuminated display in a generally conventional manner whereby light from the bulbs 17 passes through the portions of the diffusing panel 19 and is blocked by the wall 16, to illuminate and define the word EXIT. Because, however, the housing 12 is of a compact configuration with the walls 14 and 16 closely spaced, light passing through portions of the panel 19 closely adjacent the bulbs 17 will be relatively intensely illuminated, whereas remote portions of the panel 19, as for example adjacent the bottom of the housing, will be relatively less intensely illuminated. As noted hereinabove, it has been found generally impractical in many instances to dispose bulbs 17 throughout the housing 12 in a manner to provide more uniform illumination, and the most expedient arrangement for the disclosed lighting fixture has been found to be mounting the four bulbs 17 adjacent the top of the housing as shown.

An. important feature of the present invention relates to the provision of means for providing a more uniform illumination of the panel 19 described above, whereby the relatively'intense illumination adjacent the bulbs 17 is reduced and the illumination at remote regions is increased. In accordance with the invention, a generally diaphanous light equalizing panel 22 is dispo-sed in overlying relation with the panel 19 and intermediate the latter and the bulbs 17, as best illustrated in FIGURE 2. In broad terms the equalizing panel 22 includes means for blocking a portion of the light from the bulbs 17 directed toward closely adjacent portions of the panel 19, thus reducing the localized intensity of illumination and thereby improving the over-all uniformity of illumination. The extent to which light is blocked is gradually reduced with regard to light directed to progressively further spaced portions of the panel 19. In addition to blocking light in the above manner, the equalizing panel 22 further includes means for refiecting the blocked light away from the panel 19. In this manner, by providing the interior surface 23 of the wall 14 with a reflective finish, the light reflected from the panel 22 is then reflected Iback toward the display panel 19, thereby increasing the illumination of portions of the panel 19 disposed relatively remotely from the bulbs 17. As depicted in FIGURE 4 the panel 22 has a region 24 of relatively great opacity, and is disposed for positioning adjacent the most intensely lighted portions of the panel 19. Portions 26 and 27 of the panel 22 are disposed on either side of the portion 24 and represent regions of gradually decreasing opacity commensurate with permitting sufficient light transmission therethrough to illuminate corresponding portions of the panel 19 in a generally uniform manner.

The characteristic of varying opacity in the equalizing panel 22 as described above can be achieved in various manners, one of which would be simply to take a uniformly translucent panel and paint a plurality of opaque lines thereacross with the area occupied by the lines determing the opacity for any given region of the panel. A preferred construction of the equalizing panel 22 is depicted in FIGURE and consists basically in forming a plastic translucent panel with a half-tone screen printed sheet imbedded therein. More specifically, a suitable light diffusing panel for use in lighting fixtures is formed by imbedding random Fiberglas strands 2S in a liquid resin binder, such as polyester, and then setting the resin with heat in a conventional manner. To provide a varying opacity panel in accordance with the invention, a sheet of porous paper 29 is suspended in the liquid resin overlying the Fiberglas 28 as depicted in FIGURE 5. A pattern utilizing a half-tone screen process is printed on the sheet 29 with a substantially opaque ink, whereby the printed dots of the half-tone screen pattern serve to block light directed at the panel 22. The paper 29 which is porous is generally translucent in the regions interposed between the half-tone printed dots, whereby the over-all opacity of the panel 22 is determined by the area occupied by the printed dots. In this manner, a suitable half-tone screen pattern can be provided to create the varying opacity characteristic as described 4with regard to FIG- URE 4.

As already noted, the equalizing panel 22 in addition to blocking light from the bulbs 17 also reflects the blocked light towards the wall 14 so that it can be again reflected back toward remote portions of the panel 19. In this regard, such function is accomplished in the preferred embodiment of the present invention by utilizing an ink in the above described half-tone print that has highly reflective properties. An opaque white ink has been found suitable for this purpose, although aluminized or other metallic paints can also be used to achieve the necessary reflective property. Thus, light directed at the printed half-tone dots is both blocked by the dots from being transmitted through to the panel 19 and is also reflected away from the panel 19 by the reflective surface afforded by the dots.

Considering now some of the details of the housing 12, it will be seen that the housing includes a generally rectangular frame member 31 formed of a pair of identical die cast portions 32 and 33 secured together, for example, by the threaded fastening means 34 shown in FIGURE 2. The front wall 16 can be pivotally secured adjacent its lower end to the portion 33 by suitable pivot means and secured adjacent its upper end by means of a screw member 36. As depicted in FIGURE 3, the wall 16 can be pivoted downwardly to a substantially horizontal position to open the housing for access to replace the bulbs 17. The back wall 14 is provided with flanges 37 and can be secured within the portion 32 of the frame 31 by a tight interference fit. In instances where it is required to provide a two sided display fixture, the wall 14 can be removed and an assembly including components similar to the wall 16, display panel 19 and equalizing panel 22 can be mounted on the portion 31 in place of the wall 14.

The bulbs 17 are seen to be mounted on a generally V-shaped bracket member 38 which is secured adjacent the upper end of the housing. The angularly disposed downwardly facing surfaces 39 and 41 of the member 38 serve to reflect light downwardly towards the remote portions of the panel 19, thereby aiding the achievement of uniform panel illumination. As shown, suitable clip members 42 are provided to secure the panels 19 and 22 in overlying relation with the wall 16. The entire housing 12 can be secured subjacent a suitable mounting member 43 as shown, to enable its mounting on a ceiling or other structure. It will be appreciated that when a display assembly is utilized in place of the solid Wall 14, that the equalizing panel of the display assembly will function as a reflector in a manner similar to the reflective surface 23 of the wall 14. Moreover, light reflected from one display panel will be utilized in illuminating the opposmg display panel.

While the preferred embodiment of the present 1nvention has been described hereinabove with regard to the relatively thin compact display lighting fixture, it will be appreciated that the invention may be utilized in other lighting situations. Thus, for example, in various fixtures utilized for lighting purposes only, there is a fluorescent or incandescent bulb placed relatively closely to a diffuser globe or panel whereby the bulb is outlined by a relatively localized intense region of illumination on the panel or globe. This non-uniformity can be overcome by interposing a varying opacity equalizing panel between the lbulb and the outer diffusing panel in the same manner as described hereinabove with regard to the display lighting fixture 11.

What is claimed is:

1. Apparatus of the type described comprising, a panel having light transmitting portions, illumination means disposed adjacent said panel and spaced at varying distances from said panel portions, said means directing progressively relatively lesser magnitudes of light intensity to panel portions spaced `relatively further from said means, light equalizing means interposed between said panel and illumination means for blocking part of the light directed to said panel portions, said equalizing means blocking progressively relatively greater percentages of light directed to panel portions spaced relatively closer to said illumination means, and said light equalizing means includes means for reflecting away from said panel the light blocked therefrom and further reflecting Imeans for reflecting said blocked reflected light back towards said panel to increase the light intensity at relatively remote panel portions over that provided by direct lighting `from said ill-umination means. v

2. Apparatus of the type described comprising, a panel having light transmitting portions, illumination means dispose-d adjacent said panel and spaced at varying distances from said panel portions, said means directing -progressively relatively lesser magnitudes of light intensity to panel portions spacedrelatively further from said means, light equalizing means interposed between said panel and illumination means -for blocking part of the light .directed to said panel portions, said equalizing means blocking progressively relatively greater percentages 'of light directed to panel portions spaced relatively closer to said illumination means, said light equalizing means includes a generally diaphanous equalizing panel disposed in generally overlying relation with said first panel and having a varying opacity throughout its p0rtions commensurate with blocking progressively relatively greater percentages of light directed towards said first panel portions spaced relatively closer to said illumination means and said equalizing panel is also provided with a partially reflective surface for reflecting said blocked light away from said first panel, and reflecting means for reflecting said blocked reflected light back towards said first panel to increase the light intensity of relatively remote portions thereof over that provide-d by direct lighting from said illumination means.

3. Apparatus of the type described comprising, a panel having light transmitting portions, illumination means disposed adjacent said panel and spaced at varying distances from said panel portions, said 4means directing progressively relatively lesser magnitudes of light intensity to panel portions spaced relatively further from said means, light equalizing means interposed between said panel and illumination means for blocking part of the light directed to said panel portions, sai-d equalizin-g means blocking progressively relatively greater percentages of light directed to panel portions spaced relatively closer to said illumination means, said light equalizing means includes a generally diaphanous equalizing panel disposed in generally overlying relation with said first panel and having a varying opacity throughout its portions commensurate with blocking progressively relatively greater percentages of light directed towards said first panel portions spaced relatively closer to said illumination means, said equalizing panel also includes a layer of intermixed adjacent light transmitting and light blocking portions, the percentage of area of a given equalizing panel portion occupied by said blocking portions deter-mining the opacity of said given portion, said -blocking portions are reective to reflect away from said first panel said blocked light, and reflecting means for reflecting said blocked reiiected light back towards said lirst panel to increase the light intensity at relatively remote portions thereof over that provided by direct lighting from said illumination means.

4. Apparatus as described in claim 3 wherein said layer consists of a generally translucent sheet of material having a half-tone screen pattern printed thereon, said printed pattern having a light reliecting characteristic.

5. Apparatus of the type described comprising, a housing including two parallel closely spaced walls, a light source interposed between said Walls, one of -said walls including a display panel havin-g light transmitting portions spaced at Varying distances from said source, a light equalizing panel interposed between said one wall and said source and dispose-d in generally overlying relation with said display panel, said equalizing panel having a varying opacity throughout its portions commensurate with blocking progressively relatively greater percentages yof light directed toward said display panel portions spaced relatively closer to -said illuminati-on means, and said equalizing panel is also provided with a partially reective surface for reflecting said blocked light away from said display panel, said other wall being provided with a reflective surface for reflecting light toward said display panel for increasing the light intensity at relatively remote display panel portions over that provided by direct lighting of said illumination means.

6. Apparatus as described in claim 5 wherein said other wall includes a second display panel and second light equalizing panel similar in construction and disposition to said rst display an-d blocking panels.

7. Apparatus `of the type described comprising, a housing including two parallel closely spaced Walls, a light source interposed between said walls, one of said walls including a display panel having light transmitting portions spaced at varying distances from said source, a light `equalizing panel interposed between said lone wall and said source and disposed in generally overlying relation withsaid display panel, said equalizing panel having a varying opacity throughout its portions commensurate with blocking progressively relatively greater percentages of light directed toward said display panel portions spaced relatively closer to said illumination means, said equalizing panel' also includes a layer of intermixed adjacent light transmitting and light blocking portions, the percentage of area of a given equalizing panel portion occupied by said blocking portions determining the opacity of said `given portion, .said layer consists of a generally translucent sheet of material having a half-tone screen pattern printed thereon, said printed pattern having a reflective characteristic for reflecting Isaid blocked light away from said display panel, and said other wall being provided with a reflective surface vfor reecting light toward said display panel for increasing the light intensity at relatively remote display panel portions over that provided by direct lighting from said illumination means.

References Cited by the Examiner UNITED STATES PATENTS 2,507,552 5/1950 Teele 24U-46.51 X 2,855,500 10/1958 Holman 24U-46.59 X 3,020,801 2/1962 Lander et al. 95-102 X NORTON ANSHER, Primary Examiner.

C. R. RHODES, Assistant Examiner.

Claims (1)

1. APPARATUS OF THE TYPE DESCRIBED COMPRISING, A PANEL HAVING LIGHT TRANSMITTING PORTIONS, ILLUMINATION MEANS DISPOSED ADJACENT SAID PANEL AND SPACED AT VARYING DISTANCES FROM SAID PANEL PORTIONS, SAID MEANS DIRECTING PROGRESSIVELY RELATIVELY LESSER MAGNTITUDES OF LIGHT INTENSITY TO PANEL PORTIONS SPACED RELATIVELY FURTHER FROM SAID MEANS, LIGHT EQUALIZING MEANS INTERPOSED BETWEEN SAID PANEL AND ILLUMINATION MEANS FOR BLOCKING PART OF THE LIGHT DIRECTED TO SAID PANEL PORTIONS, SAID EQUALIZING MEANS BLOCKING PROGRESSIVELY RELATIVELY GREATER PERCENTAGES OF LIGHT DIRECTED TO PANEL PORTIONS SPACED RELATIVELY CLOSER

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