Optics: image projectors – Composite projected image – Reflector between lamp and screen
Reexamination Certificate
2003-06-05
2004-11-16
Dowling, William C. (Department: 2851)
Optics: image projectors
Composite projected image
Reflector between lamp and screen
C353S098000, C349S007000
Reexamination Certificate
active
06817719
ABSTRACT:
The invention relates to an apparatus for projecting a multi-colored picture on a projection screen, having a light source that emits heterochromatic light, a color unit arranged following the light source, having a first and a second light modulator arranged following the color unit, and a projection optics where the color unit can be illuminated with the light emitted from the light source and separates light of a first color and directs it on the first light modulator, and separates light of a second color and directs it on the second light modulator, where the light modulators modulate the light shining on them in order to create one color frame each of the multi-colored picture, and where the modulated light is superimposed to form a common luminous beam by means of the color unit, where the luminous beam illuminates the projection optics.
In such an apparatus, as is described in EP 0 734 183 A2, for example, the required focal intercept is very large due to the color unit provided between the projection optics and the light modulators by means of which the color frames are set. This necessitates a very complicated projection optics with numerous lenses which makes projection optics expensive and weighty. In addition, the color unit usually comprises glass elements with dichroic coatings, so that a long glass way exists between the light modulators and the projection optics which has to be passed through by the different-colored light in order to generate the color frames. The result is a transverse achromatic aberration due to the state of dispersion of the glass elements, so that the different color components of a pixel no longer overlap but are situated next to each other in the projection screen. This transverse achromatic aberration has to be compensated for by means of the projection optics, which in turn calls for a complicated structure of the projection optics.
In order to avoid the transverse achromatic aberration, lenses made of optical flint and lenses made of optical crown are combined in order to generate the required achromatization, wherein Flourite is often used which is very difficult to work. This makes the production of the projection optics very complicated. In addition, Fluorit has disadvantageous hygroscopic characteristics that can adversely affect the imaging characteristics of the projection optics over time.
Based on this situation, it is the object of the present invention to improve an apparatus of the above-mentioned kind for projecting a multi-colored picture on a projection screen in such a way that its design is simplified.
Taking an apparatus of the above-mentioned kind for projecting a multi-colored picture on a projection screen, the object is completed by connecting an optics system illuminated with a common luminous beam and having a curved mirror is provided between the color unit and the projection optics, where the optics system generates a multi-colored intermediate image in an intermediate image level arranged in front of the projection optics, where the multi-colored intermediate image is projected by the projection optics on the projection screen as the multi-colored picture.
The invention relates to an apparatus for projecting a multi-colored picture on a projection screen, having a light source that emits heterochromatic light, a color unit arranged following the light source, having a first and a second light modulator arranged following the color unit, and a projection optics where the color unit can be illuminated with the light emitted from the light source and separates light of a first color and directs it on the first light modulator, and separates light of a second color and directs it on the second light modulator, where the light modulators modulate the light shining on them in order to create one color frame each of the multi-colored picture, and where the modulated light is superimposed to form a common luminous beam by means of the color unit, where the luminous beam illuminates the projection optics.
In such an apparatus, as is described in EP 0 734 183 A2, for example, the required focal intercept is very large due to the color unit provided between the projection optics and the light modulators by means of which the color frames are set. This necessitates a very complicated projection optics with numerous lenses which makes projection optics expensive and weighty. In addition, the color unit usually comprises glass elements with dichroic coatings, so that a long glass way exists between the light modulators and the projection optics which has to be passed through by the different-colored light in order to generate the color frames. The result is a transverse achromatic aberration due to the state of dispersion of the glass elements, so that the different color components of a pixel no longer overlap but are situated next to each other in the projection screen. This transverse achromatic aberration has to be compensated for by means of the projection optics, which in turn calls for a complicated structure of the projection optics.
In order to avoid the transverse achromatic aberration, lenses made of optical flint and lenses made of optical crown are combined in order to generate the required achromatization, wherein Flourite is often used which is very difficult to work. This makes the production of the projection optics very complicated. In addition, Fluorit has disadvantageous hygroscopic characteristics that can adversely affect the imaging characteristics of the projection optics over time.
Based on this situation, it is the object of the present invention to improve an apparatus of the above-mentioned kind for projecting a multi-colored picture on a projection screen in such a way that its design is simplified.
Taking an apparatus of the above-mentioned kind for projecting a multi-colored picture on a projection screen, the object is completed by connecting an optics system illuminated with a common luminous beam and having a curved mirror is provided between the color unit and the projection optics, where the optics system generates a multi-colored intermediate image in an intermediate image level arranged in front of the projection optics, where the multi-colored intermediate image is projected by the projection optics on the projection screen as the multi-colored picture.
By providing the optics system that generates the intermediate image (preferably a real intermediate image) in the intermediate image level located in front of the projection optics (the intermediate image level can preferably also be located directly in front of the projection optics), the required focal intercept of the projection optics is much smaller in the apparatus according to the invention than the apparatus of the above-mentioned kind. This also lowers the optical requirements of the projection optics substantially, of course, so that the design of the projection optics is noticeably simplified. The number of required lenses of the projection optics is lower, in particular, which also allows for a weight reduction.
In addition, the projection optics can also be provided and designed entirely independently from the rest of the apparatus, since its task is to image the intermediate image generated in the intermediate image level, and not the picture-generating areas of the light modulators, on the projection screen.
Also, in the apparatus according to the invention, the projection optics may easily be replaced by another projection optics, so that the apparatus according to the invention may be adapted easily to diverse basic conditions, such as a wide angle projection or a projection where the optical axis of the projection optics includes an angle unequal to 90 degrees with the projection screen.
Besides folding of the path of the rays, the curved mirror also contributes to the imaging process, so that therefore the number of optic elements of the optics system may be further reduced.
The light modulators which are preferably reflective light modulators (which advantageously allow the realization of a very compact apparatu
Muehlhoff Dirk
Piehler Eberhard
Pretorius Marco
Rudolph Guenter
Carl Zeiss Jena GmbH
Dowling William C.
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