WO2008079117A1

WO2008079117A1 - Rear projection display with image rotation

Info

Publication number: WO2008079117A1
Application number: PCT/US2006/048969
Authority: WO
Inventors: Mark Alan Schultz
Original assignee: Thomson Licensing
Priority date: 2006-12-20
Filing date: 2006-12-20
Publication date: 2008-07-03

Abstract

The invention provides a projection system, for example, for a rear projection display (1). The projection system includes a projector (12), a mirror (11), and a screen (10). The projector projects an image oriented in an initial direction toward the mirror. The mirror is arranged at an angle relative to the screen. The mirror rotates the image about 90 degrees to a final direction that is about 90 degrees from the initial direction and reflects the image oriented in the final direction onto the screen.

Description

REAR PROJECTION DISPLAY WITH IMAGE ROTATION

Field of the Invention

The present invention relates to a rear projection display having a projection system provided with a mirror configured and arranged to rotate an initial direction of an image to a final direction that is about 90 degrees from the initial direction.

Background of the Invention

A rear projection display has a projection system consisting of a projector, a mirror, and a screen. In a typical projection system, the screen is configured to extend in a horizontal or X-direction. During operation, the projector projects an image oriented in a horizontal or X-direction onto the mirror. The mirror rotates the image about 180 degrees and reflects the image onto the screen. Because the image is rotated 180 degrees, the image on the screen still extends in the horizontal or X-direction. The image therefore correctly fits the screen.

Recently, rear projection systems are desired where the screen extends in a vertical or Y-direction. Because conventional projectors are configured to project images oriented in a horizontal or X-direction, in order to obtain an image that correctly fits a screen that extends in the vertical or Y-direction, the projector in the projection system must be turned on its side or at an angle of about 90 degrees. Conventional projectors, however, are manufactured to be mounted in an upright or upside-down position and are not recommended to be mounted on their side or at an angle of about 90 degrees. For example, mounting a conventional projector on its side at an angle of about 90 degrees causes poor heat dissipation, which ultimately shortens the life of the projector. Additionally, mounting a conventional projector on its side or at an angle of about 90 degrees increases the depth of the rear projection display. It is therefore desirable to provide a rear projection display with a projection system wherein- the image projected by the projector can be rotated about 90 degrees so that the image can correctly fit a vertically oriented screen while enabling the projector to be mounted upright or upside-down according to manufacturer guidelines.

Summary of the Invention

The invention provides a projection system, for example, for a rear projection display. The projection system includes a projector, a mirror, and a screen. The projector projects an image oriented in an initial direction toward the mirror. The mirror is arranged at an angle relative to the screen. The mirror rotates the image about 90 degrees to a final direction that is about 90 degrees from the initial direction and reflects the image oriented in the final direction onto the screen.

Brief Description of the Drawings

The invention will now be described by way of example with reference to the accompanying drawings.

Figure 1 is a schematic diagram of a rear projection display according to the invention.

Figure 2 is a schematic diagram of a projection system for the rear projection display of Figure 1.

Figure 3 is a schematic diagram of the projection system for the rear projection display of Figure 1 showing an image formed thereby.

Figure 4 is a schematic diagram of an alternate embodiment of a projection system for the rear projection display of Figure 1. Detailed Description of the Invention

Figure 1 shows a rear projection display 1 according to the invention. As shown in Figure 1, the rear projection display 1 includes a cabinet 2 and a projection system 3. The cabinet 2 has opposing front and rear surfaces 4, 5, opposing top and bottom surfaces 6, 7, and opposing side surfaces 8 (only one of the side surfaces 8 is shown in Figure 1), respectively. A screen receiving opening 9 is formed in the front surface 4. The cabinet 2 has a depth 13 extending in a z-direction between the front and rear surfaces 4, 5.

As shown in Figure 1 , the projection system 3 includes a screen 10, a mirror 11 , and a projector 12. The screen 10 is arranged in the screen receiving opening 9. As shown in Figure 2, the screen 10 has a height 14 extending in a vertical or Y-direction and a width 15 extending in a horizontal or X-direction. In the illustrated embodiment, the height 14 of the screen 10 is longer than the width 15 of the screen 10 such that the screen 10. Because the configuration and operation of the screen 10 is well known in the art, further description thereof will not be provided herein.

As shown in Figure 1, the mirror 11 is provided proximate the top and rear surfaces 6, 5 of the cabinet 2 and is arranged at an angle with respect to the screen 10. As shown in Figure 2, the mirror 11 includes a first mirror surface 16 and a second mirror surface 17. The first mirror surface 16 is mounted to the second mirror surface 17 such that the first mirror surface 16 is positioned at an angle 18 of about 90 degrees from the second mirror surface 17. The size of the first and second mirror surfaces 16, 17 is based on the type of optics used in the projection system 3 and/or the size of an image 27 (Figure 3) that is to be projected thereon.

The mirror 1 1 is mounted in the cabinet 2 such that the first and second mirror surfaces 16, 17 face the front surface 4 of the cabinet 2. The first mirror surface 16 is positioned at an angle 19 of about 45 degrees with respect to the screen 10 in the X-direction and the second mirror surface 17 is positioned at an angle 22 of about 45 degrees with respect to the screen 10 in the X-direction. The first and second mirror surfaces 16, 17 are rotated away from the front surface 4 of the cabinet 2 an angle 20 of about 45 degrees with respect to the screen 10 in the Y-direction, and are positioned at an angle 21 of about 45 degrees with respect to the screen 10 in the Z-direction. As shown in Figure 1 , the mirror 11 may be mounted in the cabinet 2 by a mounting member 28. The first and second mirror surfaces 16, 17 may be formed to have a dimension a few inches larger than the size necessary for the projection of the image 27 (Figure 3) thereon so that the mirror 11 can more easily be mounted in the cabinet 2.

As shown in Figure 2, the projector 12 is mounted in the cabinet 2 substantially underneath the screen 10 and in substantially the same plane as the screen 10. The projector 12 is mounted either upright or upside-down within the cabinet 2. The projector 12 is mounted such that diverging light rays 23 projected from the projector are projected substantially normal to the screen 10 and toward the first mirror surface 16 arranged proximate the rear surface 5 of the cabinet 2. Because the configuration and operation of the projector 12 is well known in the art, further description thereof will not be provided herein.

Figures 2-3 show a method of inverting the image 27 using the projection system 3. As shown in Figure 2, the projector 12 projects the light rays 23 toward the first surface 16 of the mirror 11. As shown in Figure 3, the light rays 23 contain an image 27 oriented in an initial direction 24. In the illustrated embodiment, the initial direction is in the horizontal or X-direction. As shown in Figure 2, the light rays 23 are incident on the first surface 16 of the mirror 1 1. As shown in Figure 3, the image 27 on the first surface 16 of the mirror 11 is rotated about 45 degrees from the initial direction 24 and is reflectively flipped as a result of the light rays 23 being reflected from the first mirror surface 16. As shown in Figure 2, the light rays 23 are then reflected toward the second surface 17 of the mirror 11 and are incident thereon. As shown in Figure 3, the image 27 on the second surface 17 of the mirror 1 1 is rotated about an additional 45 degrees with respect to the image 27 on the first surface 16 of the mirror 11 and is reflectively flipped as a result of the light rays 23 being reflected from the second mirror surface 17. The image 27 on the second mirror surface 17 has therefore been rotated a total of about 90 degrees.

As shown in Figure 2, the light rays 23 are then reflected toward the screen 10 and are incident thereon. As shown in Figure 3, the image 27 is projected onto the screen 10 (not shown in Figure 3) a distance 26 behind the projector 10. The image 27 on the screen 10 is oriented in a final direction 25. The final direction 25 is rotated about 90 degrees from the initial direction 24. In the illustrated embodiment, the final direction 25 is in the vertical or Y-direction. The image 27 may then be flipped to a desired orientation, for example, by an image processor (not shown) to obtain a desired final image. In the illustrated embodiment, the initial direction 24 of the image 27 is in the horizontal or X-direction and the final direction 25 of the image 27 is in the vertical or Y-direction, however, it will be appreciated by those skilled in the art that the rear projection system 3 can additionally be applied to an image having an initial direction that is in the vertical or Y-direction so that the final direction of the image 27 is in the horizontal or X-direction.

Figure 4 shows an alternate embodiment of the projection system 3 of the present invention. The embodiment shown in Figure 4 differs from the embodiment shown in Figures 1-3 in that the mirror 11 is mounted in the cabinet 2 such that the light rays 23 have a shorter path from the projector 12 to the screen 10. As shown in Figure 4, the first mirror surface 16 is positioned at an angle 19 of about 40 degrees with respect to the screen 10 in the X-direction and the second mirror surface 17 is positioned at an angle 22 of about 50 degrees with respect to the screen 10 in the X-direction. The deviations of the angles 19, 22 from the embodiment shown in Figures 1 -3 results in differences in image gain on various portions of the screen 10. Thus, by varying the angles 19, 20, 21, 22 of the first and second mirror surfaces 16, 17 with respect to the screen 10 and the projector 12 in the X, Y, and Z directions, the resulting image size, keystone adjustments, and amount of rotation can be adjusted using only the mirror 11.

The projection system 3 of the rear projection display 1 according to the invention rotates the image 27 projected by the projector 12 about 90 degrees in an effective and cost efficient manner so that the image 27 can correctly fit a vertically oriented screen. Because the projector 12 can be used in an upright or in an upside-down position, the projector 12 can be mounted according to manufacturer guidelines, which prolongs the life of the projector 12. Additionally, the configuration and positioning of the projection system 3 enables the depth 13 of the cabinet 2 to be decreased.

Although the method of rotating the image 27 about 90 degrees with the projection system 3 is shown and described herein as being used in the rear projection display 1, it will be appreciated by those skilled in the art that the projection system 3 and/or the method of rotating the image 27 about 90 degrees shown and described herein could alternatively be used in other applications. For example, the projection system 3 and/or the method of rotating the image 27 about 90 degrees shown and described herein could also be used in a front projection device (not shown).

The foregoing illustrates some of the possibilities for practicing the invention. Many other embodiments are possible within the scope and spirit of the invention. For example, in the illustrated embodiment, the projection system 3 only contains a single projector 12, however, multiple projectors could be used to obtain a higher resolution image. Additionally, multiple projection systems that each projects a segment of an image could be used to create a single image. It is, therefore, intended that the foregoing description be regarded as illustrative rather than limiting, and that the scope of the invention is given by the appended claims together with their full range of equivalents.

Claims

1. A projection system, comprising: a screen; a projector projecting an image oriented in an initial direction toward a mirror; and the mirror being arranged at an angle relative to the screen, the mirror rotating the image about 90 degrees to a final direction that is about 90 degrees from the initial direction and reflecting the image oriented in the final direction onto the screen. 1. The projection system of claim I₅ wherein the mirror has a first mirror surface and a second mirror surface.

3. The projection system of claim 2, wherein the first mirror surface is mounted at an angle of about 90 degrees from the second mirror surface.

4. The projection system of claim 3, wherein the image is projected onto the first mirror surface.

5. The projection system of claim 2, wherein the screen extends in an X-direction and a Y-direction, the first and second mirror surfaces being positioned at an angle of about 45 degrees with respect to the screen in the X-direction.

6. The projection system of claim 5, wherein the first and second mirror surfaces are rotated away from the screen at an angle of about 45 degrees with respect to the screen in the Y-direction and are positioned at an angle of about 45 degrees with respect to the screen in a Z-direction.

7. The projection system of claim 2, wherein the screen extends in an X-direction and a Y-direction, the first and second mirror surfaces being positioned at different angles with respect to the screen in the X-direction.

8. The projection system of claim 7, wherein the first mirror surface is positioned at an angle of about 40 degrees with respect to the screen in the X-direction and the second mirror surface 17 is positioned at an angle of about 50 degrees with respect to the screen in the X-direction.

9. A rear projection display, comprising: a projection system including a projector, a mirror, and a screen; the screen extending in an X-direction and a Y-direction; the projector being mounted substantially underneath the screen for projecting diverging light rays toward the mirror; and the mirror having a first mirror surface and a second mirror surface facing the screen, the first and second mirror surfaces being positioned at an angle of about 45 degrees with respect to the screen in the X-direction for reflecting the diverging light rays onto the screen.

10. The rear projection display of claim 9, wherein the first mirror surface is mounted at an angle of about 90 degrees from the second mirror surface.

1 1. The rear projection display of claim 9, wherein the first and second mirror surfaces are rotated away from the screen at an angle of about 45 degrees with respect to the screen in the Y-direction and are positioned at an angle of about 45 degrees with respect to the screen in a Z-direction.

12. The rear projection display of claim 9, wherein the first and second mirror surfaces are positioned at the same angle with respect to the screen in the X-direction.

13. The rear projection display of claim 9, wherein the first and second mirror surfaces are positioned at different angles with respect to the screen in the X-direction.

14. The rear projection display of claim 13, wherein the first mirror surface is positioned at an angle of about 40 degrees with respect to the screen in the X-direction and the second mirror surface is positioned at an angle of about 50 degrees with respect to the screen in the X-direction.

15. A method of rotating an image about 90 degrees, comprising the steps of: arranging a mirror at an angle relative to a screen; projecting an image oriented in an initial direction toward the mirror; rotating the image from the initial direction to a final direction that is about 90 degrees from the initial direction; and reflecting the image oriented in the final direction onto the screen.

16. The method of claim 15, further comprising the step of configuring the mirror to have a first mirror surface and a second mirror surface.

17. The method of claim 16, further comprising the step of mounting the first mirror surface at an angle of about 90 degrees from the second mirror surface.

18. The method of claim 16, wherein the image is projected onto the first mirror surface.

19. The method of claim 16, wherein the screen extends in an X-direction and a Y- direction, the first and second mirror surfaces being positioned at an angle of about 45 degrees with respect to the screen in the X-direction.

20. The method of claim 19, wherein the first and second mirror surfaces are rotated away from the screen at an angle of about 45 degrees with respect to the screen in the Y- direction and are positioned at an angle of about 45 degrees with respect to the screen in a Z-direction.

21. The method of claim 16, wherein the screen extends in an X-direction and a Y- direction, the first and second mirror surfaces being positioned at different angles with respect to the screen in the X-direction.

2. The method of claim 21, wherein the first mirror surface is positioned at an angle of about 40 degrees with respect to the screen in the X-direction and the second mirror surface 17 is positioned at an angle of about 50 degrees with respect to the screen in the X-direction.