Optics: image projectors – Image moves on screen – Reflector between lamp and screen
Patent
1999-04-19
2000-08-08
Dowling, William
Optics: image projectors
Image moves on screen
Reflector between lamp and screen
353 99, 353121, 359223, G03B 2128
Patent
active
060991283
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a method for the three-dimensional movement of the projection beam of a video or graphics projector, wherein the projection beam coming from a light source and guided over and/or through an optoelectronic image generator and through a projection lens is deflected by means of at least one mirror to be swivelled about two axes, an X-axis extending in direction of incidence of the projection beam and a transversely extending Y-axis.
Video or graphics projectors, which provide for the projection of video images or computer graphics, have so far mostly been used for a still projection onto a given projection surface by means of a projection beam fixedly aligned with respect to this projection surface, so that these projections are bound to firmly preadjusted image positions. The application of video and graphics projections for show, advertising and simulation purposes, however, requires a three-dimensional movement of the projection beam and thus a fast movability of the precisely positionable projection beam, for which purpose it would basically be possible to support the projector in a swivel-mounted revolving shackle, which leads, however, only to a slow, low-power motional projection impaired by vibrations.
In order to achieve fast light effects and good projections moving in three dimensions, it has also already been proposed to deflect the projection beam behind the projection lens by means of a swivel-mounted mirror, but when swivelling the mirror about an axis of rotation extending in direction of incidence of the projection beam, a fundamental imaging problem arises, as the projection image also rotates in dependence on the position of the mirror, until it is upside down after a rotation of the mirror by 180.degree.. To correct this aberration, the projection beam is rotated about the beam axis behind the image generator by means of mirrors or optical prisms in accordance with WO 94/08425 or U.S. Pat. No. 4,235,535, so as to be able to project the projected image without aberrations. However, optically influencing the projection beam in this way requires a considerable constructional effort, requires a corresponding construction space, increases the light losses during the projection, and involves additional sources for optical defects, which lead to an impairment of the production quality.
It is therefore the object underlying the invention to provide a method as described above, which in an economic and inexpensive way provides for extremely fast motional projections with a perfect compensation of the aberrations resulting from the rotation of the mirror, and in addition offers the possibility for further influencing the images to be projected.
This object is solved by the invention in that when the mirror is swivelled about the X-axis, the images to be projected, which were produced by the image generator, are additionally rotated in a forced coupling with the swivel movement of the mirror, in order to compensate the occurring aberration. By means of this both simple and elegant measure the image to be projected is itself influenced in the sense of a compensation of defects, and to compensate an aberration resulting from the swivelling of the mirror, it is tracked with a fixed angle with respect to this swivel movement. In this way, special optical means for influencing the already image-bearing projection beam are avoided, and optimum projection qualities are ensured with relatively little constructional effort and space requirement.
A particularly advantageous possibility for an additional rotation of the image is obtained when the images of the image generator are rotated by means of a digital special-effects processor with a function "rotation normal to the image plane", which activates the image generator. This processor known per se in video technology or from GB 22 65 064 A offers a simple means for activating the optoelectronic image generator corresponding to the specific functions of the processor and, by means of the function "rotation normal to the image plane"
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