Patent EA-005082-B1 (EA)
Title: Projection unit
IPC: G03B21/16
Filed: 2001-09-07
Abstract: 1. A rear projection unit comprising a screen for viewing from a front side and a frame attached at the rear side of the screen, the frame having a front portion proximate the screen and a rear portion away from the screen, the rear portion including a mounting for mounting a projector at a desired position in relation to the screen wherein the frame comprises a plurality of configurable arms, the arms comprising sliding sections to extend or reduce the length of the arms and being pivotably mounted to the screen at the front portions of the arms and to a rear section at the rear portion of the arms thereby being moveable to change the position of the mounting for the projector with respect to the screen. 2. A projection unit according to claim 1, wherein the rear section supports mounting. 3. A projection unit according to claim 1 or 2, wherein the arms are connected to the rear section at points defining a shape of the same aspect ratio as the points at which the arms are pivotably mounted to the screen. 4. A projection unit according to claim 1,2 or 3, wherein the screen and rear section are rectangular, and the points at which the arms are connected are corners of the rectangles. 5. A projection unit according to any of claims 1 to 4, wherein the mounting is supported by the rear section so that a projector mounted on the mounting is positioned centrally with respect to the screen when the arms are equal length. 6. A projection unit according to claim 1, wherein the frame is smaller at the rear portion than at the front portion. 7. A projection unit according to claim 1 or 2, wherein the frame tapers from the front portion to the rear portion. 8. A projection unit according to claim 1,2 or 3, wherein the frame is a truncated pyramid in shape. 9. A projection unit according to any preceding claim, wherein the unit includes a light absorbing material arranged to define a main cavity within the frame bordered by the screen at one side and the light absorbing material on other sides. 10. A projection unit according to claim 9, wherein the light absorbing material defines a cavity which tapers from the screen to the rear, whereby extraneous light within the cavity is directed to the rear of the unit away from the screen. 11. A projection unit according to claim 9 or 10, wherein the light absorbing material comprises a cloth with a dark inner side stretched over the frame. 12. A projection unit according to claim 9, 10 or 11, further comprising one or more baffles arranged within the cavity for absorbing extraneous light and arranged away from the cone of light produced by a projector so as not to impede projection. 13. A projection unit according to claim 12, wherein the one or more baffles are attached to the inside of the frame. 14. A rear projection unit comprising a screen for viewing from a front side and a frame attached at the rear side of the screen, the frame having a front portion proximate the screen and a rear portion away from the screen, the rear portion including a mounting for mounting a projector at a desired position in relation to the screen wherein the unit includes a light absorbing material arranged to define a main cavity within the frame bordered by the screen at one side and the light absorbing material on other sides and further comprising a second light absorbing material arranged to define an inner cavity within the main cavity bounded by the screen and the second light absorbing material, and having an aperture for receipt of the lens of a projector mounted outside the inner cavity, but within the main cavity. 15. A projection unit according to claim 14, wherein the second light absorbing material comprises a pyramid or cone suspended within the frame and the light absorbing material defining the main cavity comprises a cloth stretched over the frame. 16. A projection unit according to claim 14 or 15, wherein the light absorbing material arranged to define the inner cavity comprises one or more light absorbing boards. 17. A projection unit according to claim 14 or 15, wherein the second light absorbing material comprises a cloth. 18. A projection unit according to any of claims 15 to 17, wherein the second light absorbing material comprises a series of light traps arranged to absorb light within the inner cavity. 19. A projection unit according to any of claims 14 to 17, wherein the light absorbing material defining the main cavity comprises a cloth stretched over the frame. 20. A projection unit according to any of claims 9 to 19, further comprising an extraction fan arranged to draw cooling air over a projector within the main cavity and to expel air from the cavity thereby drawing air into the main cavity through the light absorbing material, whereby the air passing over the projector is filtered through the light absorbing material. 21. A projection unit according to any of claims 14 or 20, wherein the light absorbing material comprises a cloth with a dark inner side stretched over the frame. 22. A projection unit according to any of claims 14 to 21, further comprising one or more baffles arranged within the cavity for absorbing extraneous light and arranged away from the cone of light produced by a projector so as not to impede projection. 23. A projection unit according to claim 22, wherein the one or more baffles are attached to the inside of the frame. 24. A rear projection unit comprising a screen for viewing from a front side and a frame attached at the rear side of the screen, the frame having a front portion proximate the screen and a rear portion away from the screen, the rear portion including a mounting for mounting a projector at a desired position in relation to the screen, wherein the unit includes a light absorbing material arranged to define a main cavity within the frame bordered by the screen at one side and the light absorbing material on other sides and further comprising an extraction fan arranged to draw cooling air over a projector within the main cavity and to expel air from the cavity thereby drawing air into the main cavity through the light absorbing material, whereby the air passing over the projector is filtered through the light absorbing material