IL114769A - Lcd contact printer - Google Patents

Description

rr^T-u n-,iu',aa ruuin vm nag-rn AN LCD CONTACT PRINTER MOSHE GINSBURG ΙΊΏ.Τ Ι -· Ι niun C: 22144 AN LCD CONTACT PRINTER FIELD OF THE INVENTION This invention is related to the art of photographic contact printing and to liquid crystal displays.

BACKGROUND OF THE INVENTION Most known methods of printing images from electronic or digital sources require a printed media or a printing means which moves during the printing process. For example, in a thermal printer, such as a facsimile device, a thermal print head moves along thermal print media. The paper is fed forward after each printed line. Thus, if the paper transport is not smooth, there will be distortions in the resulting image.

Another example is ink jet printing. Ink jet printers have ink nozzles which move across a sheet of paper, which is fed forward after each printed line. In ink jets, distortions can result from irregularities in the motion of the print head and/or from irregularities in the paper transport.

Another shortcoming of most printing methods is their slow speed. Fast laser printers have a maximum printing rate of about 16 pages per minute. Video printers can only print about 2 pages per minute. Thus, if it is desired to print several consecutive frames from a video image, the frames must be digitized, stored and printed sequentially. Also, some printing methods, such as thermal printing, require a special type of paper. Printing in color is generally both more expensive and more time consuming than printing monochrome images .

It is also possible to photograph images displayed on a TV or computer screen using conventional photographic methods. However, computer screens are usually., not flat, so the resulting photographs are distorted and sometimes partially out of focus, since not all parts of the screen are at the same distance from the camera. In addition, since CRTs (Cathode Ray Tubes) do not have a uniform intensity, the resulting photograph is generally not uniform either. The photographic medium used in the camera is developed to obtain a negative and prints are made from the negative. Self processing films, such as Polaroid (tm) film, are limited to small sizes of prints by distortions inherent in camera optics. Large print sizes require a two step photographic process. Yet another disadvantage of conventional photographic methods is the difficulty in matching between the dynamic range of the images shown on the screen and that of a photographic medium.

U.S. Patent No. 5,140,428 describes a combination LCD (Liquid Crystal Display) projector and printer system. An LCD which is back-illuminated by a strong light source is used to project an image on a screen. Some of the light passing through the LCD is shunted by a partially reflective mirror and a lens system to illuminate a photographic medium. Printing of the projected image is initiated by freezing the projected image and opening an LC (Liquid Crystal) shutter situated between the LCD and the photographic medium. However, since the optical path between the LCD and the photographic medium is long, the system requires occasional focus calibration.

SUMMARY OF THE INVENTION It is an object of an aspect of the present invention to provide a versatile device for photographic printing of electronic images based on LCD (Liquid Crystal Display) technology. Another object of some aspects of the present invention is to provide a low cost, high quality printer for printing of electronic images and in particular color video images from VCRs, TVs and computers.

In a preferred embodiment of the invention, an image to be printed is displayed on an LCD which is back-illuminated by a beam of substantially parallel light rays. A photographic medium is placed on or near the LCD, substantially in parallel with the surfaces of the LCD, such that the image appearing on the LCD is transferred to the medium. Preferably, the LCD is controlled by an electronic controller which includes an image processor. The image to be printed is downloaded from a computer or acquired by a frame grabber. Alternatively, a live video signal is used to drive the LCD. Preferably, a photographic developing subsystem is included in the LCD printer so that a photo-processed print is outputted from the printer. Alternatively, a self developing medium, such as a Polaroid (tm) film is used.

Thus, an LCD printer is realized which directly prints computer and video images, without intermediate storage or display. Distortions, such as those caused by photographing a computer or video display, are generally not added to the image. The included image processor is useful for correcting and changing the image before printing and, optionally, for adding overlays. In addition, the printing parameters can be optimized in response to image attributes which are determined by the image processor.

It should be noted that the medium need not be in actual contact with the LCD, since the light passing through the LCD is substantially in parallel rays. Thus, if the medium is placed parallel to the LCD, preferably, at a small distance therefrom, contact printing quality is maintained. Parallel ray printing, as opposed to printing through a lens has a significant advantage in that no focusing is needed. Thus, less accuracy is needed in locating the photographic medium at a specific distance from the LCD. Also, there is a lower probability of image degradation if the LCD printer is jolted or is affected by severe temperature changes, such as by heating.

Since there are no moving parts in the LCD printer during printing, constant size and resolution are obtainable without the need for precise mechanical machining and calibration.

Yet another advantage of an LCD printer according to a preferred embodiment of the invention is the inherent speed of the photographic process. For example, images can be printed at a rate of 60 images per second, provided that the paper transport is sufficiently fast and the medium is sufficiently sensitive and the light source sufficiently intense.

The LCD printer is not limited to a specific type of photographic medium. Rather, the LCD printer can be configured for use with most common types of photographic films, slides and papers. Different print media may require changing the configuration of system defaults, such as color spectrum correction, color control and exposure time, which are typically provided by appropriate hardware or software. In addition, the LCD printer can be configured for use with circuit boards which are coated with a light sensitive photo-resist, instead of a light-sensitive medium.

Positive type printing media, e.g., reverse processing paper or slide film, can be used with the same apparatus used for negative printing, by reversing (the colors of) the image displayed on the LCD, i.e., by switching from a negative to a positive image or vice versa. It should be appreciated that both positive and negative images may be printed with equal ease, since the electronic image processing enables to reverse the colors in the image.

The LCD printer preferably uses a color LCD to print color images and a monochrome LCD to print monochrome images. However, in one preferred embodiment of the present invention, color images are printed using a monochrome LCD using a multiple color light source and/or appropriate filters. The medium is exposed separately to the different color components, e.g. red green and blue. This method yields a higher resolution than using a color LCD.

According to an aspect of a preferred embodiment of the present invention, the LCD printer provides electronic control of photographic variables. The exposure time and the light intensity are preferably both controlled by the electronic controller. In addition, the processor can process the image to change the color balance and the shades of the image displayed on the LCD. In addition, the processor can change the scale of the image in a very precise manner. The relative intensities of the different color components can also be controlled by controlling the light attenuation of the different color components on the LCD through an LCD driver or by changing the exposure time of each color component .

When dynamic images, for example, video images are printed directly from a video source, the timing of the frames is preferably controlled by the electronic controller. A printing of the frames may be synchronized to the video source and the exposure may be triggered and controlled externally by a video trigger.

In a preferred embodiment of the invention the LCD printer is contained in a light-proof box which is opened only to change medium or paper as in a camera. Thus, it is relatively easy to maintain a very low level of light inside the LCD printer.

In another preferred embodiment of the invention, the LCD printer is controlled by an external computer. An operator prepares images on the computer usincj image processing software. The photographic parameters, such as exposure, are preferably determined and/or controlled by the computer. Printing is performed automatically by the computer which sends an image to the LCD printer, sets the photographic parameters and triggers and controls the exposure of the medium.

According to another, generally simpler, embodiment of the invention, an LCD is driven directly by an input signal. Exposure of a medium, such as a Polaroid (tm) film, is controlled using a mechanical shutter. If the intensity of the light source which is used to expose the medium is sufficiently weak, the exposure time is sufficiently long to span several frame times of the input signal. Thus, movement of the shutter does not affect the quality of the resulting print. The color spectrum of the light source and the LCD are preferably adapted to the relative sensitivity of the medium to different wavelengths.

There is therefore provided in accordance with a preferred embodiment of the present invention a method of photographic printing of an electronic image, comprising driving an LCD in accordance with a pattern corresponding to the electronic image, illuminating the LCD with substantially parallel light rays to produce a beam of substantially parallel light rays which carries the pattern and exposing a light sensitive medium to the pattern carrying light beam for a determined period of time.

There is provided according to another preferred embodiment of the invention a method of photographically printing of a color electronic image, comprising decomposing the image into a plurality of color component images, driving an LCD in accordance with a pattern corresponding to one of the plurality of color component images, illuminating the LCD with parallel light rays, at a predetermined wavelength range corresponding to the color component to produce a pattern carrying beam of substantially parallel light rays, which carries the color component pattern, exposing a light sensitive medium to the pattern carrying beam for a determined period of time and repeating the illuminating, the driving and the exposing for at least two of the plurality of color component images .

There is also provided, in accordance with another preferred embodiment of the present invention, an LCD printer comprising an LCD which is driven in accordance with a pattern corresponding to an electronic image to be printed, a parallel light ray generator which illuminates the LCD with substantially parallel light rays to produce an beam of substantially parallel light rays which carries said pattern and a receptacle which accommodates a light sensitive medium in a position suitable for exposing the medium to the image carrying beam.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be better understood from the following detailed description of preferred embodiments of the invention, taken in conjunction with the following drawings in which: Fig. 1 is a schematic diagram of a parallel ray LCD printer constructed and operative in accordance with a preferred embodiment of the present invention; and Fig. 2 is a general block diagram of circuitry useful for the operation of the LCD printer of Fig. 1, in accordance with a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Fig. 1 is a schematic diagram of a Liquid Crystal Display (LCD) printer 9 for photographic printing of an electronic image, in accordance with a preferred embodiment of the present invention. An LCD (Liquid Crystal Display) 24 is driven to attenuate light in a pattern which corresponds to the electronic image. Preferably, LCD 24 is a color LCD, e.g, an LCD having a color-filter faceplate configuration thereon. Printing is achieved by illuminating a photographic printing medium 28, such as film or photographic paper, through LCD 24, parallel light rays generated by a parallel light ray generator 38. Medium 28 is preferably separated from LCD 24 by a sheet 26 of glass, or any other transparent material to prevent contact between medium 28 and the generally sensitive surface of LCD 24. Preferably, glass 26 is tinted to correct for systematic color biases of LCD 24 and/or light generator 38. Additionally or alternatively, the color spectrum of light generator 38 and LCD 24 is controlled by adjusting the color balance and the display times of color components on LCD 24, as described below.

In a further preferred embodiment of the invention, medium 28 is fed from a medium source (not shown), using a medium transport 32. Preferably, medium transport 32 includes a medium cassette or medium roll. Thus, high speed printing is mechanically possible provided that medium 28 is sufficiently sensitive. For example, if medium 28 is mounted on a roll and has a specified exposure time of 1/60 -of a second or: shorter for a given light generator 38, consecutive frames of a 30 HZ video signal can be individually printed on consecutive portions of medium 28. Alternatively, medium 28 "is inserted and/or removed manually .

For printing of hard prints, medium 28 is preferably a conventional photographic printing substrate. However, to print slides or overviews, a transparent printing medium may be used. In a preferred embodiment of the invention, after exposure, medium 28 is transported to an internal development system 30 of LCD printer 9. In addition, LCD printer 9 is preferably contained in a light-proof housing 40 so that medium 28 is not exposed to external light. Alternatively, medium 28 can be a self developing medium such as Polaroid (tm) film.

In a preferred embodiment of the invention, parallel light ray generator 38 comprises a light source 10, typically, a high power Halogen lamp. Preferably, light source 10 has a back reflector 12 which concentrates most of the light from light source 10 in the direction of LCD 24. A first lens 14 focuses light from light source 10 to an image plane 42. Preferably, a pinhole (not shown) is located near image plane 42 to prevent illumination of LCD 24 by extraneous light from light source 10.

In addition to or alternatively to tinting glass 26, a color filter 27 is used to correct the color spectrum of light source 10 and LCD 24. Preferably, filter 27 is located near image plane 42.

Preferably, a variable aperture 18, desirably located on image plane 42, is used to control the intensity of light emitted by light generator 38. Additionally or alternatively, the intensity of light source 10 is controlled directly, for example by controlling the voltage supplied thereto. In a fully closed position, aperture 18 can also be used as a shutter to block off all light from light source 10 between exposures. Alternatively or additionally, a light shutter may be used to block out light from light source 10. This prevents medium 28 from being exposed to light before being properly placed or before LCD 24 is driven to display the desired image. Optionally, aperture 18 is a one cell LCD. It should be noted that the dynamic range of LCDs is typically on the order of 1:50. Thus, if aperture 18 is an LCD or if LCD 24 itself is used as the aperture, the maximum attenuation state of the LCD does not usually provide sufficient light attenuation to avoid undue exposure of medium 28. Alternatively, aperture 18 has two states. One in which it blocks light from source 10 and another in which it is a pinhole.

Preferably, the light from light source 10 is diffused by a diffuser 16, to overcome inhomogenity which may be caused by the geometry of light source 10 and or reflector 12. Also, the intensity of light source 10 may be regulated by a voltage regulator .

A second lens 22, positioned such that one of its foci is approximately on the image plane of the light from light source 10, refracts the light to form substantially parallel light rays.

Alternatively, any other suitable parallel light ray sources may be used, as are known in the art. For example, a scanning laser beam.

Preferably, LCD printer 9 is adapted to print images from a variety of source types, such as PAL video, NTSC video, computer bit streams, HDTV, computer display formats and others, as is well known in the art. Thus, LCD printer 9 may be selectably connected to a plurality of image sources.

In a preferred embodiment, LCD printer 9 operates in either of two modes of synchronization. In a first synchronization mode LCD printer 9 acquires the image to be printed, and the image is printed using an exposure timing which is independent of the image source. In a second synchronization mode, LCD printer 9 is synchronized with the image source, whereby LCD printer 9 uses exposure timing dependent on timing signals from the image source. For some image sources, such as computer files, where timing signals are not used, the second synchronization mode is not available.

Fig. 2 -is a general block diagram of circuitry used in controlling LCD printer 9 in accordance with a preferred embodiment of the present invention. An acquisitor 60 digitizes an incoming image signal, which may be a video signal. Alternatively, acquisitor 60 is an image scanner, which provides an electronic image corresponding fo a scanned optical image. Alternatively, no acquisitor is used since the incoming image signal directly drives LCD 24. An optional reformatter/selector 62 selects an input from one of a plurality of image signal sources 61 and converts the input into an image format usable in LCD printer 9. Synchronization information is preferably derived from the image signal by a sync finder 72 and passed to a controller 70. Preferably controller 70 is internal to LCD printer 9. Alternatively, an. external controller 70 is used, for example, an external computer.

Controller 70 provides the timing and control signals to be used by LCD printer 9. For example, an exposure controller 78, which controls aperture 18 and, preferably, light source 10, receives timing signals from controller 70. In addition, controller 70 preferably controls medium transport 32, activates development system 30 and supplies a "print" signal, when a printing session is to begin. Typically, a printing session is triggered by a user input, for example, by an operator pressing a button. However, in video printing, synchronizing the exposure to the vertical sync signal of the image signal is preferably performed by controller 70. In addition, when an image is downloaded from a computer for printing by LCD printer 9 or when the printing is otherwise controlled by a computer, the printing session can be initiated by a signal from the computer, typically, when the download is complete. Alternatively, printing maybe triggered by an external source, such as a video timing signal, which is detected and processed by controller 70.

Alternatively or additionally, exposure timing is set using a mechanical selector. Time measurements are performed using an internal clock, using timing signals from an external source, such as a computer or by counting vertical and/or horizontal synchronizations in the input signal.

The image information is passed to an optional color processor 64, which performs at least one of the following functions : (a) processes and corrects the image; (b) translates the image colors" to appropriate signals for activating the different color pixel elements on LCD 24, for example, for color spectrum correction; (c) adds overlay information on the image, such as text; and (d) changes the size and aspect ratio of the image to fit LCD 24 and the desired printed image shape.

A frame display unit 68 determines which frame is displayed on LCD 24 and the duration of the display. Duration control is useful for providing longer exposure times for specific color components when printing using a monochrome LCD, as described below, or when printing using a color LCD. LCD controller 82, uses timing and synchronization signals from controller 70 and image frame information from frame display 68 to drive LCD 24. Alternatively, image frame information is acquired by LCD controller 82 directly from the image source signal, bypassing and mooting the need for frame display unit 68. LCD controller 82 is preferably a standard LCD controller, known in the art.

In the above described LCD printer, there are several alternative, methods of controlling the exposure of medium 28. A first method is to control the intensity of light generator 38, as described above, by controlling aperture 18 or by controlling the intensity of light source 10. A second method is to control the overall light attenuation of LCD 24, thereby changing the intensity of the light passing therethrough. If LCD 24 is a color LCD, each color component is preferably individually controlled by LCD controller 82, to provide a desired color balance. Alternatively, processor 64 or an analog gain controller (not shown) are used to individually control the gain of each color component in the image source signal .

In a further preferred embodiment of the present invention, a light sensor 34 (also shown in Fig. 1) is placed near LCD 24 to sense the intensity of light that medium 28 is actually exposed to. Preferably, sensor 34 is on the same side of LCD 24 as is medium 28. A maximum transmission region is preferably displayed on LCD 24 opposite sensor 34. Alternatively, the average intensity of the image is displayed on LCD 24 opposite sensor 34. Preferably, light sensor 34 is" positioned to receive illumination which is not dependent on the image displayed on LCD 24. It is known that light sources may change their intensity and color as they heat up and/or age. Also, different video signals have different brightness levels. A sensor controller 74 (Fig. 2), associated with sensor 34, provides controller 70 with a signal responsive to the light level which is sensed by sensor 34. Controller 70 preferably corrects the exposure timing by controlling exposure controller 78 to change the exposure time, by controlling color processor 64, by changing the display duration of the image displayed by frame display 68 and/or by controlling LCD controller 82 to change the intensity of the displayed image. Alternatively, the light intensity is measured during the exposure of medium 28 and the exposure is stopped when medium 28 is sufficiently exposed.

Preferably, the sensed light level is communicated to an external computer for future reference. Alternatively or additionally, the light level is displayed on a display 76 of LCD printer 9.

In a still further preferred embodiment, a color filter 36 is placed before sensor 34 so that the light levels for each color of the LCD are separately sensed. Preferably, four sensors 34 are used, one for each color and one for the over-all intensity. Alternatively, only three color filters 36 are used, one for each color component. Alternatively or additionally, color filters 36 are selectably placed before sensor 34 under the control of sensor controller 74. Alternatively, a portion of LCD 24, opposite sensor 34, functions as a selectable color filter. Alternatively, any color/exposure meter known in the art may be used .

It should be appreciated that many dynamic image signals, such as video signals are updated line by line, while medium 28 is exposed as a whole. Thus, controller 70 and exposure controller 78 preferably synchronize the exposure of medium 28 with the image signal so that medium 28 is exposed for an integral number of frames. Alternatively, the image is displayed on LCD 24, as a whole, after integrating, and medium 28 is exposed in accordance with the measured intensity of the image as in conventional photography.

Preferably, aperture 18 is opened only after LCD 24 displays the entire image. Alternatively, LCD 24 displays the image only after aperture 18 is opened. The choice of exposure method depends the relative reaction times of LCD 24 and aperture 18. Preferably, the exposure is controlled by the faster of LCD 24 and aperture 18. Preferably, when source 61 includes a video signal, LCD 24 and/or aperture 18 are faster than the vertical blank time of the image signal. Alternatively, a fast shutter is used, as is known in conventional photography.

In another preferred embodiment of the invention, in which LCD printer 9 is synchronized with image source 61, the image source signal is not digitized. LCD controller 82 controls LCD 24 directly by displaying on LCD 24 a dynamic image corresponding to the image source signal. Intensity feedback is provided by sensor 34 through sensor controller 74, as described above. The exposure of medium 28 in this embodiment of the invention is synchronized with the image source signal to the extent of ensuring that medium 28 is exposed to an integral number of frames and/or to a predetermined number of frames. Preferably, this synchronization is achieved by counting frame synchronization signals in the dynamic image source signal .

In the preferred embodiments of the invention described above, LCD 24 is either a color LCD, if color printing is desired or a monochrome LCD, if monochrome printing is desired. Monochrome LCDs generally have a higher inherent resolution and contrast than color LCDs. Thus, in an alternative, preferred, embodiment of the invention, a monochrome LCD is utilized for color printing by printing each color component of the image separately on the same medium 28. A selectable color filter 20 converts white light from light generator 38 into monochrome light at a predetermined wavelength range. LCD 24 is driven to display the desired image using only the color component which matches the selected filter color, so that medium 28 is exposed to one color component at a time."' Preferably, processor 64 decomposes the source color image to form the individual component color images. If a positive image is printed on a negative type medium, negative color components are used.

Preferably, selectable color filter 20 is placed inside light generator 38, such as near aperture 18. Alternatively, a different color light source is used for each monochrome image.

If a dynamic image, e.g., a video source, is being printed, it is preferred to freeze the image before printing if the total exposure time of medium 28 is longer than one frame time. Preferably, processor 64 freezes the image before each exposure. Alternatively, acquisitor 60 freezes the input signal before exposure.

Preferably, processor 64, LCD controller 82 and filters 20 are controlled by controller 70, to achieve the synchronization between displaying a color component and filtering light generator 38 to illuminate with the same color component. Additionally or alternatively, sensor 34 is used in conjunction with selectable color filter 36 to sense the intensity of monochrome light reaching medium 28.

When printing in color, the intensity of each color component is further controllable by using an individual exposure time for the printing of each color component. In a color LCD this may be achieved by blanking some of the color components for part of the printing process.

In a preferred embodiment of the invention, LCD printer 9 includes various additional features. For example, the printed image can be vertically mirrored relative to the original image using any of the following methods : (a) mirroring the image using reformatter/selector 62 during the conversion process; (b) installing LCD 24 such that it faces medium 28 instead of light generator 38; (c) mirroring the displayed image through LCD controller 82 by driving LCD 24 in an opposite direction; or (d) mirroring the image using color processor 64 as part of the image processing.

Another example of the versatility of LCD printer 9 is its ability to print positive or negative images. To print a positive image on a negative medium, the image signal is converted into a frame (for a color LCD) or set of frames (for color printing using a monochrome LCD) which form the negative of the original image. Preferably, processor 64 performs this conversion. Alternatively, an analog negation is performed. To print a negative image on the same negative medium, the colors of the image are not reversed, however, color adjustments, as described above may be performed.

It should be noted that the present invention is advantageous for uses beyond LCD printing of computer or video images, as described above. For example, it can be used as part of a development system used in photographic laboratories. The present invention is also particularly useful for processing of images acquired by digital cameras or by video-recorders.

Another preferred use of LCD printer 9 is in preparing color plates for a lithographic printing process. In such a case, LCD printer 9 is configured to print each color component on a different lithographic medium 28. The registerability of the resulting color plates is high since there is very little distortion in the process of transferring the image from LCD 24 to medium 28. Since the size of LCD 24 is constant and the light passing therethrough is substantially in parallel rays, there are no deviations in the size of the resulting color plates.

Yet another preferred use of LCD printer 9 is in preparing lithographic masks for printed circuit boards. Thus, in a further preferred embodiment of the invention, circuit boards covered with photo-resist are used in place of medium 28. LCD printer 9 may also be used as a mask for etching circuit boards. The development of the photo-resist is preferably performed by a subsystem of LCD printer 9.

The present invention may also be used for photocopying of documents and the like. A scanner (not shown) scans documents and sends image data to color processor 64. The image is printed on medium 28, as described above. Preferably, LCD 24 is large enough to accommodate standard paper sizes, such as A4. It should be noted that no distortion effects are expected even if such large medium sizes are used, in contrast to a regular camera, where expensive optics are used to minimize distortions such as those related to spherical aberrations. Alternatively or additionally, LCD printer 9 can be used as a computer printer to directly print information received by reformatter/selector 62 from a computer.

It should be appreciated that the present invention is not limited to a specific type of LCD device and that any LCD suitable for use as a back-illuminated display can be used for LCD 24. In addition, other types of electronic image masks can be used instead of LCD 24 for at least some embodiments of the present invention, for example, an array of electro-mechanical shutters .

It should also be appreciated that some of the abovedescribed functions of controller 70 and processor 64 may be performed by an external computer. An example of a preferred usage of an embodiment of the present invention is an operator using an image processing software running on the external computer. The computer acquires images from any computer readable source, such as diskettes, tapes or using a frame grabber. The operator processes the images, such as for enlarging, for adding overlays and/or for adjusting colors and chooses which images to print. Further, printing parameters, such as, panning, zooming, exposure time, medium type, color spectrum control and type (positive or negative) printing are determined for each image. LCD printer 9 is preferably controlled by the computer to automatically print images in accordance with user guidelines. Preferably, the images are transferred to LCD printer 9 by a computer display adapter which provides a video signal to LCD printer 9 and/or to the computer display.

It will be appreciated by people skilled in the art that a different type of electronic light attenuation device may be used instead of LCD 24, for at least some aspects of the present invention.

It will be appreciated by persons skilled in the art that the present invention is not limited to what has been thus far been described. Rather, the scope of the present invention is limited only by the following claims:

Claims (33)

1. A method of printing an electronic image, comprising: driving an LCD (Liquid Crystal Display) in accordance with a pattern responsive to said image; illuminating said LCD with substantially parallel light rays to produce a beam of substantially parallel light rays which carries said pattern; and exposing a light sensitive medium to said pattern carrying light beam for a determined period of time.

2. A method of printing an electronic color image, comprising: decomposing said image to a plurality of color component images; driving an LCD (Liquid Crystal Display) in accordance with a pattern responsive to one of said plurality of color component images; illuminating said LCD with parallel light rays, at a predetermined wavelength range corresponding to said color component, to produce a pattern carrying beam of substantially parallel light rays, which carries the color component pattern; exposing a light sensitive medium to said pattern carrying beam for a determined period of time; and repeating said illuminating, said driving and said exposing for at least two of said plurality of color component images.

3. A method according to claim 2, wherein the exposure times of at least two of said color components are not equal.

4. A method according to any of the preceding claims, comprising placing said light sensitive medium in close proximity with said LCD.

5. A method according to claim 4, wherein said exposing comprises placing said light sensitive medium substantially in contact with said LCD.

6. A method according to any of the preceding claims, further comprising photo-processing said light sensitive medium.

7. A method according to any of the preceding claims, wherein said image is an electronic image comprising a plurality of frames and wherein said determined period of time is an integral number of frame times.

8. A method according to any of the preceding claims, further comprising : sensing the light intensity of at least a portion of said pattern carrying beam; and determining the exposure time of said light sensitive medium based on said measured intensity.

9. A method according to any of the preceding claims, wherein driving said LCD comprises driving said LCD with a pattern corresponding to the negative of said image.

10. A method according to any of the preceding claims, wherein driving said LCD comprises driving said LCD with a pattern corresponding to said image.

11. A method according to any of the preceding claims, further comprising controlling the relative intensities of color components of said image.

12. A method according to claim 11, "wherein said LCD is a color LCD having a plurality of individual color components and wherein said controlling comprises adjusting the relative intensities of said plurality of color components of said LCD.

13. A method according to any of the preceding claims further comprising processing said electronic image before driving said LCD.

14. An LCD printer comprising: an LCD driven in accordance with a pattern corresponding to an electronic image to be printed; a parallel light ray generator which illuminates said LCD with substantially parallel light rays to produce a beam of substantially parallel light rays which carries said pattern; and a receptacle which accommodates a light sensitive medium in a position suitable for exposure of said medium to said beam.

15. A printer according to claim 14, wherein said light sensitive medium comprises a circuit board coated with photoresist.

16. A printer according to claim 14, wherein said light sensitive medium comprises a self developing medium.

17. A printer according to claim 14, wherein said light sensitive medium comprises a photographic film.

18. A printer according to claim 14, wherein said light sensitive medium comprises a photographic paper.

19. A printer according to any of claims 14-18, further comprising a photo-processing unit for processing said medium.

20. A printer according to any of claims 14-19, further comprising a feeder which feeds said medium into said receptacle.

21. A printer according to any of claims 14-20, further comprising a sensor which measures the intensity of said pattern carrying beam for determining the exposure time of said medium to said beam.

22. A printer according to any of claims 14-21, wherein said light generator comprises: a light source; at least one lens which produces said parallel rays using light from said light source; and a shutter which selectably blocks light from said light source .

23. A printer according to any of claims 14-22, further comprising at least one filter which corrects the color spectrum of said light generator.

24. A printer according to any of claims 14-23, further comprising a controller which controls the exposure time of said medium to said beam.

25. A printer according to any of claims 14-24, further comprising an image processor which processes said electronic image.

26. A printer according to any of claims 14-25, wherein said image comprises an electronic signal and further comprising a synchronizer which synchronizes the exposure of said medium with said signal.

27. A printer according to any of claims 14-26, further comprising an image source which provides said image.

28. A printer according to claim 27, wherein said image source comprises a processor.

29. A printer according to claim 28, wherein said processor comprises a computer.

30. A printer according to claim 27, wherein said image source comprises a video cassette player.

31. A printer substantially as shown and described hereinabove.

32. A method of printing substantially as shown and described hereinabove.

33. A printer substantially as illustrated in any of the drawings .