GB2089169A

GB2089169A - An electronic camera

Info

Publication number: GB2089169A
Application number: GB8137118A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-12-10
Filing date: 1981-12-09
Publication date: 1982-06-16
Also published as: GB2090503A

Abstract

An electronic still camera for the capture and storage of still pictures utilises a solid state camera, an analogue to digital signal converter, a frame-grabber in the form of a high speed temporary memory capable of capturing and holding picture information output from the analogue to digital converter and holding it a sufficient time to load it into a solid state memory which is capable of storing more than one picture. The solid state memory may be a magnetic bubble memory which can be permanently installed in the camera and capable of dumping its picture information onto an external memory, or the solid state memory may be in the form of a removable chip or cassette. <IMAGE>

Description

SPECIFICATION An electronic camera This invention relates to electronic cameras, and has particular application to an electronic still camera capable of recording and storing a plurality of pictures which can then be played back on a video monitor, T.V. screen, or converted into hard copy prints.

Prior art The following relate to the capture and storage of a still picture by electronic means.

U.S.P. 4262301 to Erlichman (assigned to Polaroid Corporation).

4074324 to Barrett 4057830 to Adcock (assigned to Texas Instruments Inc.) U.S.P. 4130834 to Mender (assigned to Video Print GmbH) Barrett is concerned with the instantaneous production of hard copy prints, and includes only a temporary memory as a buffer between the analogue to digital converter and the mechanical scanning printer.

The other three patents utilise a temporary memory and a permanent memory in the form of magnetic tapes.

Other patents of interest in this area relate to Video cameras, and facsimile systems, and iclude: U.S.P.

3962725 to Lemke et. al.

U.S.P. 3833758 to Ferrari U.S.P. 3482040 to Brinster U.S.P. 4008372 to Ueno et. al.

U.S.P. 3864514 to Lemelson By way of contrast, the present invention provides an electronic camera icluding imaging means, a receptor capable of converting an image from said imaging means into a digital signal, a temporary memory capable of capturing picture information as it is output from the receptor, control means, and a solid state permanent memory capable of storing more than one picture.

The utilisation of a solid state permanent memory capable of storing more than one picture, enables the camera to be compact and robust as it does not require the presence of moving parts, for example in the case of the magnetic tape storage utilised in the above cameras or the hard copy print out utilised in 4074324.

Other aspects of this invention which should be considered in all its novel aspects will become apparent from the following description which is given by way of example only, with reference to the accompanying drawings, in which: Figure 1 illustrates the exterior of a prototype electronic still camera.

Figure 2 is a block diagram of the prototype electronic still camera.

Figure 3 is an interior view of the prototype camera.

The prototype illustrated in Figures 1 to 3 can be constructed from off-the-shelf solid state components involving the combination of an image sensor, an analogue to digital signal converter, a high speed memory, and a permanent memory.

Image sensor This consists of a matrix of photodiodes or charge coupled devices. The array converts incident light energy to electrical output signals whose amplitude is proportional to the light intensity integrated over the exposure time. The number of elements in the array determines the resolution of the image. Image sensing devices such as these available at present for black and white operation, e.g. EG & G RETICON produce photodiode arrays up to a maximum resolution of 100 x 100. A number of companies also incorporate CCD type image sensors in their video cameras. The image sensing device is used in conjunction with a standard camera lens system to enable images to be accurately focussed on the element matrix. Refer to U.S.P.

4262301 if coloured pictures are required, as the contents of that patent are incorporated herein by way of reference.

Analogue to digital converter This would be used to convert the outputs from the element matrix into digital form suitable for storage in semiconductor memory. Because of the large amount of information contained in one image and the speed at which the image must be acquired, it will be necessary to use a very high speed A/D converter. We can estimate the speed required. Assume an image resolution of 1024 x 1024 points (this is probably the minimum resolution which would be required if high quality pictures would be required). Also assume that the shutter speeds on the camera would be similar to those found on cameras at present, i.e. 2 seconds to 1/1000 of a second. Note that the risetime of the diodes might prevent such fast shutter speeds.

Number of elements = 1024 x 1024 Minimum sampling time = 1,048,576 Thus sampling rate required= 1050 MHz High speed memory This would be for "capturing" one picture as it is output by the A/D converter. Note that the sampling rate derived above means that the memory will have to be very fast, i.e. it will have to have an access time of about 1 ns. Note that the specifications given above for the A/D converter and high speed memory assume that single devices perform the desired function. It would be possible to reduce these specifications if some sort of parallel operation was implements, where more than one device was used for each function. Again, the storage time of the diodes could relax this requirement by allowing a fast shutter speed and a longer time to read out the image to memory.

Permanent memory This memory will perform a function similar to that of film, i.e. it will store the images ready to be viewed at a later time. At this stage it would appear that bubble memory would be the most suitable for this function.

A preview facility could be built into the camera by optionally displaying the image stored in the fast memory onto an image monitor, e.g. a diode matrix. If the picture is acceptable, the contents of the fast memory could then be loaded into the permanent memory otherwise a new picture could be taken overwriting the old one. The pictures could be viewed, perhaps by "playing" the permanent memory back, through the appropriate DIA converters and video interface, on a standard T.V. set. A video disc or tape could also be used for permanent storage of the pictures leaving the permanent memory "film" free for another set of pictures. The video disc or tape would be analogous to a picture album, holding a large file of pictures which could be random accessed for display on the T.V. screeen.

Advantages A solid state camera would have the following advantages over a conventional camera: 1. No moving parts - hence more reliable, more suited to use in harsh environments, quieter, etc.

2. No film developing costs - once acquired the permanent memory "file" could be reused indefinitely.

3. The ability to provide an optional review facility.

Prototype construction A prototype electronic still camera is currently under construction and to demonstrate the technique of a solid state image store. The system is designed to digitise and store one image, with the resolution of 256 x 256 x 4 bits in a high speed memory in 1/50th of a second. This picture is then loaded into a bubble memory, and in the prototype this will take approximately 10 seconds per image. A similar amount of time will be involved in loading the image from the bubble memory into a RAM for display.

By utilising a bubble memory board as described below, the camera will be capable of holding four images with a resolution of 256 x 256 x 4 bits. It will be appreciated that the number of images will be inversely proportional to the number of bits of grey scale required for a satisfactory image. Thus increasing the number of bits of the grey scale, will decrease the number of images capable of being stored in the bubble memory.

By way of example, the prototype camera is being constructed from the following components, in conjunction with a solid state video camera (RCA model TC1160) as the sensing device, and a video monitor as the display device.

The components 1. MATROX RGB-256 - a board containing sufficient memory for a 256 x 256 picture element display with 4 bits of grey (16 levels) for each pixel and on board sync generators for reading the contents of memory out to a video monitor.

2. MATROX FG-01 - a "frame-grabber" board which, when used with the EGB-256 board, enables one frame of video to be digitised and stored in memory, i.e. it will digitise one image with 256 x 256 x 4 bit resolution in 1/50th of a second.

3. INTER PLUG-A-BUBBLE - a bubble memory cassette containing 128K bytes of bubble memory and the necessary hardware to interface it to a Multibus system.

4. INTEL SCB 80/85 - an 8085A based single board computer with 512 bytes of RAM and facility for 4K of ROM.

5. INTEL SCB 635 - a 4 slot Multibus cardframe with power supply. This would hold all 4 boards mentioned above.

It will be appreciated that the above prototype has been described with reference to off-the-shell components and that by appropriately designing the components the camera can be reduced to a compact hand held or pocket camera.

Finally, it will be appreciated that various alterations or modifications may be made to the foregoing without departing from the scope of this invention as exemplified by the following claims.

Claims

1. An electronic camera including: imaging means, a receptacle capable of converting an image from said imaging means into a digital signal, a temporary memory capable of capturing picture information as it is output from the receptor, control means, and a solid state permanent memory capable of storing more than one picture.

2. An electronic camera as claimed in claim 1, wherein the permanent memory is in the form of a removable chip.

3. An electronic camera as claimed in claim 1 or claim 2, wherein the solid state memory is a magnetic bubble memory.

4. An electronic camera as claimed in claim 3 wherein said imaging means includes a matrix of photodiodes or charge coupled devices.

5. An electronic camera as claimed in claim 4, wherein said receptor consists of an analogue to digital signal converter.

6. An electronic camera substantially as hereinbefore described with reference to the accompanying drawings.