HK1035829B - Video image rotating apparatus - Google Patents

Description

Video image rotating apparatus

The present invention relates to image projection and television viewing systems; and more particularly to a method and apparatus for enabling a centrally located video image to be viewed substantially simultaneously by viewers within 360 deg. around the image.

A common problem in picture pictures, television images or screen projection displays is that the picture is viewed perfectly in front only when the viewer looks exactly perpendicular to the picture image plane. This ideal situation is difficult to achieve when some viewers watch the picture from different locations simultaneously.

One solution to this problem is to simply mount the picture on a rotating base that rotates slowly through a 360 ° range so that the viewer around the base can ultimately view the picture along a line of sight perpendicular to the plane of the picture. Such systems are commonly used for advertisement display in a wide area such as a train station. The problem with this arrangement is that the rotation of the picture must be slow in order for different viewers to have an opportunity to study the content of the picture. Such slow turning devices allow only a few people to view the picture at a time, while others who are out of the line of sight must wait before the picture turns to his own line of sight.

In many cases, it may be desirable to view the pictures or display data simultaneously and continuously in order to discuss the content of the relevant information. For example, board members typically sit around a conference table during a business meeting, and this arrangement does not allow information placed on the table to be shown to all participants. It would be advantageous if a means were provided centrally at the conference table to enable everyone to review the pictures or project information substantially simultaneously. For example, it is possible to avoid having pictures viewed successively by each board member in turn. In addition, displaying data over a 360 ° range can prevent each member from seeing a series of cluttered pictures when they are provided with a duplicate picture.

Another problem with conventional display systems is that special attention must be paid to the display locations around the display system, since conventional display systems such as televisions cannot be viewed from the rear or extreme sides. Therefore, the area in which the audience can be accommodated is limited to an appropriate line-of-sight position. The available space around the display system is then usually limited by the presence of blind spots. Furthermore, the requirement to provide a clear line of sight to the television may be disadvantageously dependent on the positioning of the device indoors.

To overcome the viewing limitations of conventional displays, 360 ° viewing systems have been developed, examples of which are shown in US 3,976,837; 4,901, 140; 4,943,851, respectively; and 4,979,026; the contents of which are incorporated herein by reference. In particular, US 4,943,851 discloses a viewing system that provides a projected image on a rear projection screen that rotates extremely quickly about a vertical axis that precisely bisects the image in the vertical plane. The rotational speed of the projection screen allows the projected image to be viewed simultaneously by a full audience at any location relative to the viewing system. The viewing system is an optical system that is synchronized with the rotation of the projection screen relative to the cathode ray tube about a vertical axis. A Liquid Crystal Display (LCD) screen is used to define a viewing window that is continuously redefined at sequential intervals to continuously maintain alignment with the projection screen. US 4,901,140 discloses a viewing system that provides a real-time image defining a very fast rotation in space, enabling all viewers to view the same image substantially simultaneously and continuously. In this configuration, the black and white images projected from the cathode ray tube are projected via a parabolic mirror to provide a real-time image in space. The LED screen is used to define a filtered viewing window that is continuously re-defined at sequential intervals so as to continuously maintain alignment in space with the rotated real-time image. The LED screen comprises filters blocking red, green and blue light, which provide color to the real-time image in space. US 4,979,026 discloses the use of a rotatable polarizing screen and a separate, stationary polarizing screen that cooperate to define a viewing window that continuously maintains alignment with a rotating real-time image in space.

While this prior 360 viewing system has significant advantages over the prior art, certain features have been added to provide a more acceptable market product. For example, such existing systems can be affected by visible blurring that occurs at the edges of the projected image as it rotates through the viewer's line of sight. It has been found that providing a slit in front of the projection screen that rotates with the screen reduces horizontal blurring of the image. Horizontal image scanning can be accomplished by viewing the screen through a slit, but most of the light from the rotating screen is lost on the inner wall of the rotating drum. Only a small part of the projected image reaches the viewer's eye via the slit. The drawback of this approach is mainly the reduced brightness of the projected image. In this respect, the apparent screen brightness is a function of the time integral of the still screen brightness and visibility functions defined by the slits. In other words, the apparent brightness of the rotating screen is 50-100 times less than the brightness of the stationary screen.

There is therefore a need for a visual display system that enables the entire audience at various locations around the display system to view video images simultaneously and minimizes the visible blur at the edges of the projected video images as much as possible. In addition, there is a need for an improved 360 viewing system that uses a stationary projector and a means to rotate the image produced by the projector in order to keep up with the rotating rear projection screen. The present invention fulfills these needs and provides other related advantages.

The present invention relates to a video image rotating apparatus or 360 deg. viewing system which enables viewers of a 360 deg. circular arc around a picture to view video images substantially simultaneously. The new 360 ° viewing system uses a plurality of light valves for producing red, green and blue images, a Phillips prism for aligning the red, green and blue images to form a full color composite image, and an optical system for directing the composite image to a rear projection screen. The rear projection screen is rotatable about an axis and has means for expanding the projected image substantially parallel to the axis of rotation of the screen and means for compressing the width of the projected image substantially perpendicular to the axis of rotation of the screen. The particular screen used eliminates the need for a shutter and significantly reduces the blurring of the projected image in prior art systems. The video image generated by the light valve may be rotated mechanically or, preferably, an electrically powered image rotation system may be employed to electrically rotate the image generated by the light valve in synchronization with the rotation of the rear projection screen.

Video image rotation devices have a wide range of uses including: commercial advertisements, and television devices and display screens for displaying travel information at airports, train stations, bus stations. The present invention is capable of delivering information to many viewers simultaneously, since the 360 display maximizes the line of sight of the viewing system and eliminates blind spots. This configuration allows great flexibility in positioning the device and viewing system within the viewing zone, thus providing greater freedom of choice in space utilization within the viewing zone.

In a preferred form of the invention, a video image rotation apparatus comprises: a projection screen, a device for rotating the projection screen about an axis, and an optical system for successively projecting images onto the projection screen. The optical system includes: light valve means, light guide means, and optical means for generating an image; wherein the optical device projects an image from the light valve device onto the light guide device, which then directs the image to the projection screen. An apparatus for rotating a projection screen comprising: means for synchronously rotating the projection screen and the light guide means having a predetermined rotational speed. The optical device further includes: the device comprises a Pechan prism and a projection lens assembly connected with the Pechan prism.

The light valve arrangement includes a plurality of high definition light valves and a phillips prism that aligns the images produced by the light valves for projection through the optical arrangement. The light guide includes first, second, third and fourth mirrors. The first mirror is positioned to intercept the projected image from the optical device and reflect the image to the second mirror. The second mirror is positioned to intercept the reflected image of the first mirror and reflect the image to the third mirror. A third mirror is provided to intercept the reflected image of the second mirror and reflect the image to a fourth mirror. And finally, intercepting the reflected image of the third reflector by the arranged fourth reflector, and reflecting the image to the projection screen. It should be noted that the first mirror and the projection screen are located on the rotation axis.

With respect to the projection screen itself, the means for extending the projected image parallel to the screen's axis of rotation comprises a first surface of the projection screen that includes small cylindrical structures on top of a positive large cylindrical structure. The large and small cylindrical structures are parallel to the width of the projection screen. In the illustrated embodiment, the small cylindrical structures comprise radial surfaces having a pitch of about 250 μm and a radius of about 213 μm. The large cylindrical structure comprises a radial surface having a radius of about 340 mm.

Means for compressing the width of the projected image generally perpendicular to the axis of the rotating screen and including a second surface of the projection screen, the means constituting a Fresnel positive cylindrical lens that is highly parallel to the projection screen. In the embodiment shown, the Fresnel lens has a pitch of about.33 mm and a focal length of about f 1-730 mm over a 360mm cylindrical radius.

In order to view the same video image from a range of 360 deg. during operation of the image rotating means, it is necessary to rotate the video image in synchronism with the rotation of the projection screen by optical means. This may allow any viewer in the audience to periodically obtain a line of sight that is aligned with the proper viewing angle of the projected image. When the rotational speed of revolutions per minute (rpm) is sufficiently large (preferably 1140rpm), all viewers around the video image rotating apparatus will see the same picture substantially simultaneously and continuously.

One simple way to rotate the video image through optical means is to rotate the Pechan prism in synchronism with the projection screen. However, a more preferred method is to rotate the electrical image through the light valve. In an electronic image rotation system, a color processing circuit is used to separate red, green, and blue (RGB) signals contained in a composite video input signal. These RGB signals are converted from analog to digital form and stored in Random Access Memory (RAM). The input address generation circuit provides inputs to the RAM from a means for separating the composite video input signal into horizontal and vertical synchronization pulses. The output generating circuit selects data stored in the RAM according to an algorithm to generate a video output signal from the stored data. The image reproduced from the video output signal will rotate around the light valve. To facilitate the generation of the video output signal, first and second buffer memories are alternately used in the RAM such that when one buffer memory stores RGB signals, the other buffer memory is used to generate the video output signal.

A stationary transparent housing surrounds the rotatable projection screen. The housing may be tinted plexiglass to reduce glare and, if desired, a concave housing surface may be used. The interior of the housing is evacuated to minimize friction and noise during operation of the video image rotating apparatus as the projection screen rotates.

Other features and advantages of the present invention will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.

The following figures depict the invention, in which:

FIG. 1 is a perspective view, partially in section, of the top and side of a video image rotating apparatus embodying the present invention;

FIG. 2 is a cross-sectional view of the video image rotating apparatus taken along line 2-2 of FIG. 1, showing various built-in components of the upper and lower portions of the apparatus, the upper portion being provided with a rotating screen and corresponding mirrors, the lower portion being provided with a drive motor, a lens device and a projection unit;

FIG. 3 is an enlarged, fragmentary, cross-sectional view of the area indicated by reference numeral 3 in FIG. 2;

FIG. 4 is an enlarged view of the projection lens assembly of FIG. 2;

FIG. 5 is a perspective view of the optical path of the projection lens arrangement to the rear projection screen;

FIG. 6 is a perspective view of three light valves surrounding a Phillips prism that collimates the image produced by the light valves for projection through the lens arrangement of FIG. 4;

FIG. 7 illustrates the working surface of one of the light valves of FIG. 6, showing a step rotation of the video image produced on the working surface, and hexagonal pixels contained on the working surface of the light valve to facilitate such step rotation;

fig. 8 is a logic diagram of a composite video signal process for producing a step-rotated image in the working plane around each of the three light valves of the phillips prism of fig. 6, where the step-rotation of the video image corresponds to a rotation of the projection screen within 360 °.

As shown in the illustrative figures, the video image rotating apparatus 10 of the present invention enables a viewer surrounding the apparatus 10 to view video images substantially simultaneously over a 360 range. The apparatus 10 utilizes a plurality of light valves 12a-c to produce a video image proximate a phillips prism 14, which phillips prism 14 collimates the video image for projection via a lens arrangement 16. Four mirrors 18, 20, 22, and 24 direct the projected image from the lens assembly 16 to a rear projection screen 26. The rear projection screen 26 has a special configuration that focuses light passing through it, thus eliminating the need for a shutter. In addition, the screen 26 expands the projected image in a direction parallel to the rotation axis.

The video image rotating apparatus 10 has a wide range of application fields including commercial advertisements, television devices, and display screens for displaying travel information at airports, bus stations, and train stations. The present invention enables information to be delivered to numerous viewers simultaneously, since the 360 display maximizes the line of sight to the viewing system and minimizes blind spots. These features may allow for more flexibility in the positioning of the device and viewing system, thus providing greater freedom of use of space within the viewing area. In addition, the video image rotating apparatus 10 of the present invention overcomes similar disadvantages in prior systems. In particular, minimizing or eliminating blurring of the video image. The present invention suitably uses light valve technology to produce a sharp image that is projected through the optics of the device. The combination of light valve technology with the new projection screen produces an image that is thirty times brighter than the original image on a normal screen.

Referring to fig. 1-7, the apparatus 10 of the present invention includes a housing 28, and a projector 30, a lens assembly 16, a first mirror 18, and a motor 31 disposed within the housing 28, the motor 31 driving the assembly that rotates with the rear projection screen 26. The base plate 32 is mounted to the upper surface of the housing 28 and includes a first window 34 from which a shaft 36 of the motor 31 extends and a second window 38, the second window 38 being aligned with the rotational axis of the rear projection screen 26. A transparent polypropylene cylinder 40 extends upwardly from the base plate 32 and a top plate 42 covers the cylinder 40 to enclose it as a sealed enclosure in which the rear projection screen 26 and other components associated with the rotatable components move.

Surrounding the second window 38 is a bearing 44, the bearing 44 rotatably supporting a drum base 46 relative to the base plate 32. The drum base 46 also includes a window 48, the window 48 being aligned with the second window through the base plate 32 and with the axis of rotation of the projection screen 26. An opaque light shield 50 extends upwardly from the drum base 46 and extends substantially with the barrel 40, except that a viewing port 52 is centrally aligned with the front surface of the rear projection screen 26.

A first mirror support 54 extends downwardly from the inner surface of the housing 28 to support the first mirror 18 in alignment with the lens assembly 16 and the window 38 through the base plate 32. As shown, the second mirror support 56 supports the second and third mirrors 20 and 22. A third mirror support 58 extends upwardly from the drum base 46 to an upper screen support 60 to position the fourth mirror 24. The mirrors 18-24 provide a means for directing the image projected by the lens assembly 16 toward the back of the rear projection screen 26. In particular, the first mirror 18 is arranged to intercept the projected image from the lens assembly 16 and reflect the image to the second mirror 20. The second mirror 20 is positioned to intercept the projected image from the first mirror 18 and reflect the image to the third mirror 22. The third mirror 22 is arranged to intercept the projected image from the second mirror 20 and reflect the image to the fourth mirror 24. A fourth mirror 24 is provided to intercept the projected image from the third mirror 22 and reflect the image to a projection screen 26. All mirrors except first mirror 18 will rotate with drum substrate 46 and projection screen 26 during operation of video image rotating apparatus 10. The first mirror 18 is stationary. To make the rotating portion of the device 10 as light as possible, the second, third and fourth mirrors 20-24 may be made of a highly reflective polyethylene terephthalate film that is coated on a styrofoam frame.

Rear projection screen 26 is generally rectangular and is supported at its upper end by an upper screen support 60 and at its lower end by a lower screen support 62. A drive pulley 64 is mounted on the end of the motor shaft 36 (between the base plate 32 and the drum base 46), and a belt 66 extends from the drive pulley 64 to a driven pulley 68 mounted on the outside of the bearing 44 to rotate the drum base 46. The illustrated design assembly rotates the drum base 46, and therefore the rear projection screen 26 and the second through fourth mirrors 20-24, at high speeds, preferably 1440 RPM. The light shield 50 forming the drum wall is opaque except for a viewing port 52 aligned with the front surface of the rear projection screen 26. Since the light shield 50 rotates with the drum base, the viewing port is always aligned with the front surface of the rear projection screen 26. The viewing port spans 55 of arc length over the circumference of the cylinder 40. Since the outer stationary cylinder 40 is transparent, a viewer surrounding the video image rotating apparatus 10 can view the screen 26 through the viewing port 52 when a portion of the rear projection screen 26 is rotated into the viewer's line of sight. Preferably, as the rear projection screen 26 rotates, a vacuum is drawn inside the cylinder 40 to reduce gas flow and resistance to the inner rotating drum, as well as noise.

The projector 30 includes a high brightness light source 70, such as a metal halide lamp, three light valves 12a-12c, and a phillips prism 14. The light valve 12 is preferably a Proxima9200 model 3-piece poly-silicon Liquid Crystal Display (LCD) light valve manufactured by Sanyo. The resolution of such a light valve is 1024 × 768. Other light valves may also be used with the present invention, such as a Texas Instrument Digital Light Processor (DLP) with three micro-mirror devices (DMDs). The term "light valve" as used herein includes LCD valves, Grating Light Valves (GLVs), Digital Micromirror Devices (DMDs), or other reflective or transmissive devices capable of producing an image based on a digital input.

Three light valves 12a-12c are arranged around a phillips prism 14, the prism 14 optically overlapping the images produced by the light valves. A standard form of light valve comprises a row and column arrangement of individual pixel cells. This form is sufficient for most applications. But as shown in fig. 7, a hexagonal mosaic is more suitable for the pixel 110. As shown in fig. 7, when, for example, a high-definition pattern is formed on a light valve constituted by hexagonal pixels 110, the pixel pattern is the same in at least six different directions. That is, as the image is rotated on the light valve, the image will be exactly the same at six locations.

The light valves 12a-12c are used in the video image rotating apparatus for a variety of reasons, not just the small physical size of typical light valve plates such as DVD, LCD or GLV. Typically, such light valves are about one square inch. The frame rate of the light valve is much higher than conventional CRT imaging systems. The light valve can produce a frame rate significantly higher than that of a CRT. In addition, the use of light valve technology can achieve many thousands of ANSI lumens, so the use of light valves in the video image rotating apparatus 10 is a desirable option.

The superimposed images produced by the light valves 12a-12c are projected through a phillips prism 14 to a lens assembly 16. The lens assembly 16 includes a Pechan prism 72 positioned between two sets of refractive lenses 74 and 76. The first lens group 74 is located in a rear barrel 78 and the second lens group 76 is located in a front barrel 80. Lens spacer 82 is used to properly position the individual lenses to achieve the desired optical effect for lens assembly 16.

The Pechan prism 72 expands the video image received from the projector 30 and if desired, the Pechan prism 72 can be used to mechanically, rather than electrically, rotate the video image in synchronization with the rear projection screen 26. Such mechanical rotation can be achieved by simply rotating the Pechan prism 72 about a longitudinal axis extending through the lens assembly 16. By rotating the Pechan prism 72 in synchronism with the rear projection screen 26, the image provided on the screen will be the same regardless of the angular orientation of the screen 26 relative to its axis of rotation.

But an electrical rotation system may also be preferred to electrically rotate the video image projected through the lens assembly 16. In this regard, and referring to FIG. 8, after processing the composite input video signal into separate forms of red, green, and blue signals and horizontal and vertical synchronization pulses, the electrical image rotation system 84 electrically rotates the video image projected by the lens assembly 16. The image rotation system rotates the image displayed by the light valves 12a-12c by electrically storing separate synchronization pulses and color data of the video input signal into a random access memory, and then processing the stored data to produce images at various angles of rotation, as shown in fig. 7.

More specifically, referring to fig. 8, the color processor circuit 86 separates the red, green and blue image data included in the composite video input signal. These analog signals are converted to digital form by analog-to-digital converters 88 a-c. After conversion to digital form, the red, green and blue image data is stored in respective Random Access Memories (RAMs) 90 a-c. The composite video input signal is also separated into horizontal and vertical sync pulses by a sync pulse separation filter circuit 92. The horizontal and vertical synchronization pulses are input to the input address generating circuits 94a-c, and the input address generating circuits 94a-c determine how the digital signals from the converters 88a-c are stored in the RAMs 90 a-c.

Each RAM90 establishes buffer memories a96 and B98, the buffer memories a96 and B98 alternately serving to receive/store input video signals and generate output rotated video signals. The digital red, green and blue image data are stored in respective buffer memories a96, and buffer memory B98 is used to generate the rotated video output signal. After the buffer memory a stores and the rotation output signal is generated in the buffer memory B, the buffer memory a and the buffer memory B are alternately used so that the color image data is stored in the buffer memory B while the buffer memory a generates the rotation output signal. The buffer memories a and B are operated alternately in this manner continuously. To facilitate storage of the received data in RAM90, input address generation circuit 94 is reset at the beginning of each video frame to select an initial predetermined RAM location for storage in either buffer A or buffer B. The timing of this reset operation coincides with every other vertical synchronization pulse input to the input address generating circuit 94 by the synchronization pulse separation filter circuit 92.

The output address generating circuits 100a-c select the data stored in the RAMs 90a-c according to an algorithm to reproduce the video output signal from the stored data. The output address generating circuits 100a-c electrically rotate the input image in a stepwise manner. The speed of this further rotation is high enough (at least 1440rpm) that the human eye can only see continuous motion. The output address generating circuits 100a-c may also utilize the algorithm to alter the rotated video output signal as desired. The output address generating circuits 100a-c supply the rotated varying video output signals and the horizontal/vertical synchronization signals to the respective light valves 12a-12c in a step-wise pulsed manner.

The viewing of the image is controlled through a window that rotates in synchronization with the screen 26. Synchronization of viewing port position with screen rotation is achieved by synchronously rotating screen circuits 102a-c, which synchronously rotate screen circuits 102a-c receive input signals from output address generating circuits 100 a-c.

The present invention is unique to the construction of rear projection screen 26. Referring to fig. 3, rear projection screen 26 has two distinct surfaces for expanding the projected image substantially parallel to the screen's axis of rotation and for compressing the projected image substantially perpendicular to the screen's axis of rotation, respectively. More specifically, the rear surface 104 of the screen 26 includes small cylindrical structures on top of positive large cylindrical structures, where the large and small cylindrical structures are parallel to the width of the projection screen. The small cylindrical structures have radial surfaces with a radius of about 213 μm, and a pitch of about 250 μm. The large cylindrical structure has a radial surface with a radius of about 340 mm. This particular surface structure may provide a means for expanding the projected image substantially parallel to the screen rotation axis as indicated by arrow 106.

The front surface 108 forms a fresnel positive cylindrical lens parallel to the height of the projection screen. The fresnel lens has a pitch of about.33 mm and a focal length of about f 1-730 mm over a 360mm radius. The front surface 108 provides a means for compressing the width of the projected image substantially perpendicular to the screen's axis of rotation. This particular configuration of rear projection screen 26 allows light generated by light source 70 to be focused into a narrow band for viewing through viewing port 51 in light shield 50. This configuration increases the intensity of light passing through the screen 26, allowing the video image rotating apparatus 10 to see a brighter image when in operation.

In operation, the red, green, and blue image data is processed by the image rotation system 84 and delivered to the corresponding light valves 12a-12c in the projector 30. The phillips prism 14 is used to combine the images from the three light valves and project the combined images through a lens assembly 16. The lens assembly 16 expands the video image and projects it onto the first mirror 18. The video image is then reflected from the first mirror 18 to the second mirror 20, the third mirror 22, the fourth mirror 24, and ultimately to the rear surface of the rear projection screen 26. The configuration of rear projection screen 26 vertically expands the projected image and constrains the horizontal width of the image, thereby concentrating the image and its intensity into a narrower region. This advantageously increases the brightness of the image viewed through window 52.

It should be appreciated that at any given time, all images received via the composite video signal need not be displayed by the video image rotation apparatus 10. It is more likely that only a part of the image contained in the composite video signal is displayed in any one rotation. However, the rotation of the rear projection screen 26 will be fast enough that the image provided by the composite video signal is reproduced in a scanning manner, thereby providing sufficient brightness and light intensity for all moving video of the human eye without producing significant blur as is already the case in a 360 viewing system.

As can be seen from the above, the video image rotating apparatus 10 of the present invention can be placed at a central location, for example, on a conference table, around which many people who wish to view pictures sit. When the electrical image rotation system 84 electronically rotates the image on the light valves 12a-12c in synchronism with the rear projection screen 26, the viewer will see the image clearly and clearly at each moment when the window 52 is aligned with the viewer's line of sight. The end result is that all present people can watch the same picture at the same time.

While particular arrangements of the invention have been described, it will be apparent that various modifications can be made without departing from the spirit and scope of the invention. Accordingly, the invention is not limited except as by the appended claims.

Claims (42)

1. A video image rotation apparatus, comprising:

a projection screen;

means for rotating said projection screen about an axis;

an optical system for successively projecting images onto said projection screen;

wherein the projection screen comprises means for expanding the projected image substantially parallel to the screen rotation axis and means for compressing the width of the projected image substantially perpendicular to the screen rotation axis; the expansion device includes a first surface of the projection screen that includes small cylindrical structures on top of positive large cylindrical structures, where the large and small cylindrical structures are parallel to the width of the projection screen.

2. The video image rotating apparatus of claim 1, wherein the small cylindrical structures have radial surfaces with a radius of about 213 μm and a pitch of about 250 μm, and the large cylindrical structures have radial surfaces with a radius of about 340 mm.

3. The video image rotating apparatus of claim 1, wherein the means for compressing the width of the projected image substantially perpendicular to the screen axis of rotation has a second surface of the projection screen that forms a fresnel positive cylindrical lens parallel to the height of the projection screen.

4. The video image rotating apparatus of claim 3, wherein the Fresnel positive cylinder lens has a pitch of about.33 mm and a focal length of about f 1-730 mm over a 360mm cylinder radius.

5. The video image rotating apparatus of claim 1, wherein the optical system comprises a light valve device for generating the image, a light guide device, and an optical device, wherein the optical device projects the image from the light valve device to the light guide device, and the light guide device then directs the image to the projection screen.

6. The video image rotating apparatus of claim 5, wherein the optical device comprises a Pechan prism.

7. The video image rotating apparatus of claim 6, wherein the means for rotating the projection screen comprises means for synchronously rotating the projection screen and the light guide at a predetermined rotational speed.

8. The video image rotating apparatus of claim 7, wherein the projection screen rotates about the axis of rotation that bisects the screen, and wherein the light guide comprises at least one mirror disposed along the axis of rotation and rotatable about the axis of rotation.

9. The video image rotating apparatus of claim 6, wherein the optical arrangement includes a projection lens assembly coupled to the Pechan prism.

10. The video image rotating apparatus of claim 5, wherein the light valve means comprises a plurality of high definition light valves and a Phillips prism that collimates images produced by the plurality of light valves for projection through the optical means.

11. The video image rotating apparatus of claim 10, wherein the light valve comprises hexagonal shaped pixel cells.

12. The video image rotating apparatus of claim 5, wherein the light guide means comprises first, second, third and fourth mirrors, wherein the first mirror is positioned to receive the projected image from the optical means and reflect the image to the second mirror, the second mirror is positioned to intercept the reflected image from the first mirror and reflect the image to the third mirror, the third mirror is positioned to intercept the reflected image from the second mirror and reflect the image to the fourth mirror, and wherein the fourth mirror is positioned to intercept the reflected image from the third mirror and reflect the image to the projection screen.

13. The video image rotating apparatus of claim 12, wherein the first mirror and the projection screen are located on the axis of rotation.

14. The video image rotating apparatus of claim 5, including an electrical image rotating system for electrically rotating the image produced by the light valve device, the image rotating system comprising:

a color processor circuit for separating red, green and blue signals contained in the composite video input signal;

analog/digital conversion means for converting the red, green and blue signals from analog to digital form;

a random access memory device for storing digital red, green and blue image data;

an output address generating circuit selects data stored in the random access memory according to an algorithm to generate a rotated video output signal from said stored image data, whereby an image reproduced from said rotated video output signal will exhibit a rotation in accordance with the stored image.

15. The video image rotating apparatus of claim 14, wherein the image rotation system further comprises an input address generation circuit that selects locations within the random access memory device for storing the digital red, green, and blue image data.

16. The video image rotating apparatus of claim 15, further comprising a separation filter circuit that separates said composite video input signal into horizontal and vertical synchronization pulses for said input address generating circuit.

17. The video image rotating apparatus of claim 16, wherein the random access memory provides first and second buffer memories, the first and second buffer memories alternately being for receiving the video input signal and generating the rotated video output signal.

18. The video image rotating apparatus of claim 17, wherein the input address generating circuit is reset to select a position at the beginning of each video frame of the first or second buffer memory every other vertical synchronization pulse.

19. A video image rotation apparatus, comprising:

a light valve means for generating a video image;

a rear projection screen rotatable about an axis;

an optical system for successively projecting said image from said light valve means onto said projection screen, said optical system comprising light guide means and optical means, wherein said optical means projects said image from the light valve means onto said light guide means which then directs the image onto said projection screen; and

video image rotating means for rotating the video image generated by said light valve means in synchronism with said projection screen rotating about said axis;

wherein said projection screen includes means for expanding said projected image substantially parallel to said screen rotation axis and means for compressing the width of said projected image substantially perpendicular to said screen rotation axis, said expanding means including a first surface of said projection screen comprising small cylindrical structures on top of positive large cylindrical structures, wherein said large and small cylindrical structures are parallel to the width of said projection screen.

20. The video image rotating apparatus of claim 19, wherein the video image rotating means has an electrical image rotating system for electrically rotating the image produced by the light valve means.

21. The video image rotating apparatus of claim 20, wherein the electrical image rotating system comprises:

a color processor circuit for separating red, green and blue signals contained in the composite video input signal;

analog/digital conversion means for converting the red, green and blue signals from analog to digital form;

a random access memory device for storing digital red, green and blue image data; and

an output address generating circuit selects data stored in the random access memory according to an algorithm to generate a rotated video output signal from said stored image data, whereby an image reproduced from said rotated video output signal will exhibit a rotation in accordance with the stored image.

22. The video image rotating apparatus of claim 21, wherein said electrical image rotating system further comprises an input address generating circuit that selects locations within said random access memory device for storing said digital red, green, and blue image data; a separation filter circuit that separates said composite video input signal into horizontal and vertical synchronization pulses for said input address generation circuit; wherein said random access memory provides first and second buffer memories alternately for receiving said video input signal and generating said rotated video output signal; and wherein said input address generating circuit is reset to select a position at the beginning of each video frame of said first or second buffer memory every other vertical synchronization pulse.

23. The video image rotating apparatus of claim 19, wherein the optical device comprises a Pechan prism.

24. The video image rotating apparatus of claim 23, wherein the optical arrangement includes a projection lens assembly coupled to the Pechan prism.

25. The video image rotating apparatus of claim 19, wherein the means for rotating the projection screen comprises means for synchronously rotating the projection screen and the light guide at a predetermined rotational speed.

26. The video image rotating apparatus of claim 19, wherein the light valve means comprises a plurality of high definition light valves.

27. The video image rotating apparatus of claim 26, wherein the light valve means further comprises a phillips prism that collimates the image produced by the plurality of light valves for projection through the optical means.

28. The video image rotating apparatus of claim 26, wherein the light valve comprises hexagonal shaped pixel cells.

29. The video image rotating apparatus of claim 19, wherein the light guide arrangement includes first, second, third and fourth mirrors, wherein the first mirror is positioned to receive the projected image from the optical arrangement and reflect the image to the second mirror, the second mirror is positioned to intercept the reflected image from the first mirror and reflect the image to the third mirror, the third mirror is positioned to intercept the reflected image from the second mirror and reflect the image to the fourth mirror, and wherein the fourth mirror is positioned to intercept the reflected image from the third mirror and reflect the image to the projection screen, the first mirror and the projection screen being positioned on the axis of rotation.

30. The video image rotating apparatus of claim 19, wherein the means for compressing the width of the projected image substantially perpendicular to the screen axis of rotation comprises a second surface of the projection screen forming a fresnel positive cylindrical lens parallel to the height of the projection screen.

31. A video image rotation apparatus, comprising:

a projection screen;

means for rotating said projection screen about an axis;

an optical system for successively projecting images onto said projection screen, said optical system comprising a light valve means for producing an image, a light guide means and an optical means, wherein said optical means projects said image from the light valve means onto said light guide means which then directs the image onto said projection screen, wherein said light valve means comprises a plurality of high definition light valves and a phillips prism which collimates the images produced by the plurality of light valves for projection through said optical means;

wherein said projection screen comprises means for expanding said projected image substantially parallel to said screen rotation axis and means for compressing the width of the projected image substantially perpendicular to said screen rotation axis, wherein said means for expanding said projected image substantially parallel to said screen rotation axis comprises a first surface of said projection screen comprising small cylindrical structures on top of positive large cylindrical structures, wherein said large and small cylindrical structures are parallel to the width of said projection screen, wherein said means for compressing the width of the projected image substantially perpendicular to said screen rotation axis has a second surface of said projection screen constituting a fresnel positive cylindrical lens parallel to the height of said projection screen.

32. The video image rotating apparatus of claim 31, wherein the optical device comprises a Pechan prism, the optical device comprising a projection lens assembly coupled to the Pechan prism.

33. The video image rotating apparatus of claim 31, wherein the means for rotating the projection screen comprises means for rotating the projection screen in synchronization with the light guide at a predetermined rotational speed, the light guide comprising first, second, third, and fourth mirrors, wherein the first mirror is arranged to receive the projected image from the optical device and reflect the image to the second mirror, the second mirror is arranged to intercept the reflected image from the first mirror and reflect the image to the third mirror, the third mirror is arranged to intercept the reflected image from the second mirror and reflect the image to the fourth mirror, the fourth reflector intercepts the reflected image from the third reflector and reflects the image to the projection screen, and the first reflector and the projection screen are positioned on the rotating shaft.

34. The video image rotating apparatus of claim 31, wherein the light valve comprises hexagonal shaped pixel cells.

35. The video image rotating apparatus of claim 31, including an electrical image rotating system for electrically rotating the image produced by the light valve device, the image rotating system comprising:

a color processor circuit for separating red, green and blue signals contained in the composite video input signal;

analog/digital conversion means for converting the red, green and blue signals from analog to digital form;

a random access memory device for storing digital red, green and blue image data;

an output address generating circuit selects data stored in the random access memory according to an algorithm to generate a rotated video output signal from said stored image data, whereby an image reproduced from said rotated video output signal will exhibit a rotation in accordance with the stored image.

36. The video image rotating apparatus of claim 35, wherein said image rotating system further comprises an input address generating circuit that selects locations within said random access memory device for storing said digital red, green, and blue image data; a separation filter circuit that separates said composite video input signal into horizontal and vertical synchronization pulses for said input address generation circuit; wherein said random access memory provides first and second buffer memories alternately for receiving said video input signal and generating said rotated video output signal; the input address generating circuit is reset to select a position at the beginning of each video frame of the first or second buffer memory every other vertical synchronization pulse.

37. A video image rotation apparatus, comprising:

a projection screen;

means for rotating said projection screen about an axis; and

an optical system for successively projecting images onto said projection screen, said optical system comprising light guide means and optical means, wherein the optical means projects an image onto said light guide means and then directs said image onto said projection screen;

wherein the projection screen includes a surface forming a fresnel positive cylindrical lens for compressing the width of the projected image substantially perpendicular to the screen axis of rotation.

38. The video image rotating apparatus of claim 37, wherein the optical system further comprises a plurality of high-definition light valves for producing the image.

39. The video image rotating apparatus of claim 37, wherein the light valve comprises hexagonal shaped pixel cells.

40. The video image rotating apparatus of claim 37, comprising a phillips prism coupled to a plurality of said high definition light valves, said phillips prism collimating images produced by the plurality of light valves for projection through said optical device.

41. The video image rotating apparatus of claim 37, wherein the projection screen includes means for expanding the projected image in a direction substantially parallel to the screen axis of rotation, the projected image expanding means including another surface of the projection screen having a small cylindrical structure on top of a positive large cylindrical structure, wherein the large and small cylindrical structures are parallel to the width of the projection screen.

42. A video image rotation apparatus, comprising:

a light valve means for generating a video image;

a rear projection screen rotatable about an axis;

an optical system for successively projecting said image from said light valve means onto said projection screen, said optical system comprising light guide means and optical means, wherein said optical means projects said image from the light valve means onto said light guide means which then directs the image onto said projection screen;

video image rotating means for rotating the video image generated by said light valve means in synchronism with said projection screen rotating about said axis.

Wherein said projection screen comprises means for expanding said projected image substantially parallel to said screen rotation axis and means for compressing the width of the projected image substantially perpendicular to said screen rotation axis, said compressing means having a second surface of said projection screen constituting a fresnel positive cylindrical lens parallel to the height of said projection screen.