Patent EA-003871-B1 (EA)
Title: A video projection system
IPC: H04N9/31
Filed: 2001-04-23
Abstract: 1. A video projection system (30) comprising means (36, 46) for generating a coloured light bundle coloured according to a video signal and means (31, 35) for line scanning the bundle onto a screen (48) thereby producing images on the-screen (48), the system (30) also including a disc (31) adapted to rotate on an axis (32) extending through a centre of the disc (31) and at right angles to a plane of the disc (31), the system (30) also including means for enlarging a horizontal projection angle, characterised in that the disc (31) carries a plurality of light guiding devices (35) extending radially of the disc (31) and spaced. one from another in an angular direction in the plane of the disc (31) and each device (35) extending at an angle to the plane of the disc (31) in a corresponding plane perpendicular to the plane of the disc (31) so that each device (35) projects a corresponding one of the lines scanning a video image onto the screen (48) and characterised in that the means for enlarging the horizontal projection angle includes a combination of mirrors for receiving a light bundle from a light guiding device (35) and for reflecting the light-bundle onto the screen (48), said combination of mirrors including a toroidal mirror. 2. A video projection system (50) as claimed in claim 1 characterised in that the combination of mirrors (51, 53, 54) includes a concave spherical mirror (53) for reflecting the light bundle from a light guiding device (35), the toroidal mirror (51) for reflecting the light bundle from the concave spherical mirror (53) and a concave cylindrical mirror (54) for reflecting the light bundle from the toroidal mirror (51) to the screen (48). 3. A video projection system. (50) as claimed in claim 2 characterised in that the toroidal mirror (51) is provided with a slot (52) which is arranged so that the light bundle incident on the concave spherical mirror (53) passes through the slot (52). 4. A video projection system (55) as claimed in claim 1 characterised in that the combination of mirrors (56, 58, 59, 60) includes a concave spherical mirror (58) for reflecting the light bundle from a light guiding device (35), a plane mirror (56) for reflecting the light bundle from the concave spherical mirror (58), the toroidal mirror (59) for reflecting the light bundle from the plane mirror (56) and a concave cylindrical mirror (60) for reflecting the light bundle from the toroidal mirror (59) to the screen (48). 5. A video projection system (55) as claimed in claim 4 characterised in that the plane mirror (56) is provided with a slot (57) which is arranged so that the light bundle incident on the concave spherical mirror (53) passes through the slot (57). 6. A video projection system as claimed in claim 2 or claim 3 characterised in that the toroidal mirror is located between the light guiding devices (35) and the axis of rotation (32) of the disc (31). 7. A video projection system as claimed in any one of the preceding claims characterised in that the devices (35) are arranged in a single helical configuration. 8. A video projection system as claimed in any one of the preceding claims characterised in that the means (36, 46) for generating a coloured light bundle coloured according to a video signal includes a number of dichroic mirrors (44, 45) to combine a number of modulated light bundles in order to create the coloured light bundle.