WO1999006870A1

WO1999006870A1 - Optical viewing device

Info

Publication number: WO1999006870A1
Application number: PCT/GB1998/002293
Authority: WO
Inventors: David Thurlow
Original assignee: David Thurlow
Priority date: 1997-08-02
Filing date: 1998-07-31
Publication date: 1999-02-11
Also published as: GB9716343D0

Abstract

An optical viewing device, such as a pair of binoculars, includes means for recording and replaying views observed therethrough. The optical arrangement consists of objective lenses (10), roof prism pairs (8), combining prisms (6) and eyepieces (5). The means for recording images is a Charge Coupled Device (3), positioned such that ray path (9) passes through one objective lens, one set of roof prism pairs and one combining prism and falls on the CCD (3). A semi-mirrored coating on the surface (7) of the interface between the combining prism (6) and the roof prism (8), diverts part of the ray path (9) back to the eyepiece allowing the observer to view the image in conjunction with it being recorded. The images recorded can be replayed to one or both eyepieces by a Liquid Crystal Display (2) via a display re-imaging lens (4) to the eyepiece (5), shown by the ray path (12). Shutters (11) are interspersed in the ray paths (9, 10) during replay in order to view the display screen (2) clearly.

Description

Optical Viewing Device

Background to the Invention

The present invention relates an optical viewing device, such as a pair of binoculars, specifically adapted so as to be able to record and replay action to the viewer.

Binoculars are commonly used for viewing distant scenes and events, particularly sporting and other fast moving activities. When observing such activities it is frequently desirable to revisit some fast moving piece of action. This can readily be achieved when observing action remotely by television, as action can be recorded whilst broadcast then retransmitted at any desired speed, so enabling slow motion action replays of events that might otherwise have gone unnoticed. A better view of events can be gained, however, by observation with binoculars to enlarge the view. The disadvantage of this method is that it is not currently possible to observe events live through binoculars, and additionally to benefit from replaying those scenes observed with the eye.

Si-jm-iarv of the Invention

According to the present invention there is provided an optical viewing device comprising at least one eyepiece through which a view enlarged by optical means can be observed, means for recording moving images viewed through the optical means, means for storing the images recorded and means for playing back these images through said at least one eyepiece, thus allowing action replays to be observed through the device .

The device may for example comprise a pair of binoculars having an optical magnification system comprising lenses and prisms and including the benefits of being able to record and review, at any desired speed, previous action observed with the eye through the binoculars . The device preferably comprises means for recording a "loop" of the most recent action. The "loop" is continuously updated whilst scenes are being viewed, so that there is always recorded the last, say, 30 seconds of action. The length of the "loop" may be of any size and is only limited by the amount of memory capacity available in the device. In order to keep the device light and handy it is preferable to use solid state memory devices such as DRAM (Dynamic Random Access Memory) to record the images, however alternatively a loop of magnetic tape, a magnetic disk or other electronic media may be used.

The user views the replayed images through either one or both of the binocular eyepieces in the same manner as he would view the original scene, the replayed image corresponding to the view through either one or both of the binocular eyepieces. Preferably, the image corresponding to the view through either one or both eyepieces is captured by means of a compact semiconductor imaging device such as a CCD (charge coupled device) or DA (diode array) . The images may be stored in semiconductor memory such as DRAM or SRAM (Static Random Access Memory) or variations or enhancements of these devices. In normal operation the images are stored as a rolling sequence, the newest image over-writing the oldest. The number of images stored depends upon the memory capacity of the device. Thus for RAM capable of storing N images (or 2N images in the case of full binocular views) the most recent N images can be played back upon request. Preferably, this sequence of N images can, furthermore, be played in normal motion, slow motion, forwards, backwards, freeze-frame and so forth. Furthermore, if desired, the memory can be made to store only a selection of images (such as every nth frame) and can in addition be switched to a "retain" mode, where the previously selected images can be stored without being overwritten until such times as the user wishes to delete them or download them into another memory bank. The memory available can be divided into sections, so that some of it is used for retained images and the remainder for rolling ones. During replay, the image can be "inched" by means of forward and backward commands so that a particular view can be precisely located. This feature may be used advantageously in conjunction with the timing of events, whereby, for example, the time gap between competitors crossing a finishing line can be measured. This "delta-time" result can then be displayed by superimposition on the viewing screen.

Images are displayed by means of LCD (Liquid Crystal Display) or AM (Active Matrix) or equivalent screens built into the device and so positioned such that the replayed images can be seen through the eyepiece (s) of the device in the same manner as the original images were viewed. In the case of binoculars, two screens may be used, one corresponding to each eyepiece, or alternatively one screen only may be used for viewing replays through one eyepiece only, or by inclusion of a beam splitter through both eyepieces. Images may be recorded by two recording means corresponding to the two eyepieces, or alternatively from one recording means and replayed through two screens. As stereoscopic vision through binoculars is very limited there is little advantage in having two recording means and it is preferable to have only one recording means for reasons of lightness and economy. If desired, the format of the image can be made compatible with that of a conventional TV display or video cassette recorder, or PC, so that the output from the binoculars can be dumped to such units to store them or display them to a wider audience. The device can be designed for monochrome or colour use, depending on cost and weight considerations. In general colour requires more data to be stored and greater battery drain.

In order to view replayed images clearly a shutter or shutters may be included to shut out light entering the binoculars during replay. It may sometimes be desirable, for instance in adverse lighting conditions, to view the images live via the display screen or screens and the view may be enhanced by the use of stroboscopic flash or infra-red etc., otherwise the scene is viewed live directly without recourse to the display screen, except when replays are required.

The image sensor used may be one of many available types, with various pixel and colour options, eg. 320x240 pixels, 640x480 pixels, 512x512 pixels, monochrome, RGB (Red, Green, Blue), etc. If for instance a 512x512 pixel RGB sensor is used it requires a storage capacity of 0.25 Megabyte per image and on European standards we assume 25 frames/second i.e. 40ms per image. To avoid "contouring" and other image artifacts it is desirable to digitise the RGB signals to 8 bits each. Thus each image uses 0.25 MB where each byte is 24 bits deep. Various forms of image data compression can be employed, both spatial and temporal, using known methods such as DCT (direct- cosine-transform) . Alternatively, a specific type of compression can be "built-in" to the camera chip; for example certain colour image sensor chips have alternating RGB stripes or filters on the chip itself, so that spatial resolution is traded for compression of the colour signal. Each image in effect consumes 0.25MB with each byte now only 8 bits wide. Thus 64 MB of RAM is sufficient for 64/0.25=256 images and at 25 frames/second this covers approximately ten seconds. Clearly smaller or larger blocks of memory can be used, depending upon size, price and battery considerations.

It will be understood that the invention is equally applicable to a telescope with a single optical path.

Brief Description of the Drawings

An embodiment of the invention will now be described by way of example only with reference to the accompanying drawings in which: -

Figure 1 is a schematic isometric view of the optical layout of a pair of binoculars according to the invention; Figure 2 is a schematic block diagram of the electronic layout of the binoculars ; and

Figure 3 is a schematic view of a control panel on the binoculars .

Detailed Description of the Preferred Rmhodiment

Figure 1 shows a binocular optical arrangement including means for recording and replaying views observed through the binoculars. The optical arrangement consists of objective lenses 1, roof prism pairs 8, combining prisms 6 and eyepieces 5. The means for recording images is a Charge Coupled Device (CCD) 3, positioned such that incoming ray path 9 passes through one objective lens, one set or roof prism pairs and one combining prism and falls on the CCD 3. A semi-mirrored coating (dielectric or metallic) on the surface 7 of the interface between the combining prism 6 and the roof prism 8 diverts part of the ray path 9 back to the eyepiece allowing the observer to view the image in conjunction with it being recorded by the CCD 3. The images recorded can be replayed to one or both eyepieces by a Liquid Crystal Display (LCD) 2 via a display re- imaging lens 4 to the eyepiece 5 as shown by ray path 12. Shutters 11 are interspersed in the ray paths 9, 10 during replay in order to view the display screen 2 clearly.

Figure 2 shows an embodiment of the electronic system required to control the invention. 10 is the input optics with OS being an optical shutter, which may be driven by a flip-motor, M, to cut out the viewed image during replay. The view is recorded by a camera "chip" CAM and relayed to an analogue to digital converter ADC and thence relayed to the image store IS, which could be RAM (random access memory) or a CCD (charge coupled device) . On replay the data stored in the IS is converted back to analogue form by a digital to analogue converter DAC, in order to drive the displays, right display RDIS and left display LDIS, which may require backlighting Bl of variable brightness Br. The displays are viewed respectively by the left and right eyes LE and RE. For certain types of CCD memory the ADC and the DAC stages may be omitted. The vital functions of the device, including the replay features and a flash F, are controlled by the Microcontroller or Microprocessor Unit MCU, powered by a battery Ba, and under the control of the user's controls UC. The MCU sends appropriate addresses ADR, clocks CX, and read/write instructions R/W to the IS, though for simplicity and economy the TV format and timing functions may be shared between the CAM and the display. The aperture control AP, may also e controlled by the MCU, as shown, or alternatively can be combined in the camera chip CAM. The output from the DAC can also be relayed to an output socket OS, via a video amplifier VA and a PAL or NTSC encoder NP, if required, for remote storage and playback.

Referring to Figure 3, a control panel UC controls the action replay binoculars. These controls may be distributed to convenient positions on the body of the binoculars .

Claims

1. An optical viewing device comprising at least one eyepiece through which a view enlarged by optical means can be observed, means for recording moving images viewed through the optical means, means for storing the images recorded and means for playing back these images through said at least one eyepiece, thus allowing action replays to be observed through the device.

2. A device according to claim 1, wherein the means for recording the images comprises a semiconductor imaging device.

3. A device according to claim 2, wherein the imaging device comprises a charge coupled device.

4. A device according to claim 2 or 3 , wherein the image storing means comprises a semiconductor memory.

5. A device according to claim 1, 2 or 3 , wherein the image storing means comprises a magnetic medium.

6. A device according to any preceding claim, wherein the images are stored as a rolling sequence, the newest image over-writing the oldest.

7. A device according to any preceding claim, wherein in an alternative mode of operation, only selected ones of the images recorded are stored in the image storing means .

8. A device according to any preceding claim, comprising timing means for measuring the interval between the recordal of two selected images.

9. A device according to any preceding claim, wherein the image play-back means comprises at least one liquid crystal display or active matrix screen.

10. A device according to any preceding claim, wherein the optical means comprises at least one objective lens and at least one prism.

11. A device according to any preceding claim, comprising at least one shutter for shutting out light from the optical means during the play-back of images.

12. A device according to any preceding claim, comprising a pair of binoculars.

13. A device according to any one of claims 1 to 13, comprising a telescope.

AMENDED CLAIMS

[received by the International Bureau on 08 December 1898 (08.12.98); original claim 1 amended; remaining claims unchanged (1 page )]

1. An optical viewing device comprising at least one eyepiece through which a view enlarged by optical means can be observed, only one means for recording moving images viewed through the optical means, means for storing the images recorded and means for playing back these images through said at least one eyepiece, thus allowing action replays to be observed through the device.

^ . A device according to claim 1 , wherein the means for recording the images comprises a semiconductor imaging device.

3. A device according to claim 2 , wherein the imaging device comprises a charge coupled device.

6. A device according to any preceding claim, wherein the images are stored as a rolling sequence, the newest image over-writing the oldest .

8. A device according to any preceding claim, comprising timing means for measuring the interval between the recordal of two selected images .