Patent Application
20070085980
Display systems project an image or series of images on a display surface. In particular, light is frequently modulated by one or more light modulator panels to form one or more image. The modulated light is then passed through display optics, which frequently magnifies the modulated light and focuses the light onto a display surface.
The display optics often includes a series of refractive lenses to provide the desired magnification and focus. In many cases, such as where high magnification is desired, many individual lenses may be required to accurately display the output of the light modulator panel on the display surface. Such lenses may also be relatively large, resulting in an overall larger size and greater expense for the display system.
A projection assembly is provided herein for use in display systems. According to one exemplary embodiment, the projection assembly includes a multi-mirror reflective ring-field type lens assembly. According to such an exemplary embodiment, the projection assembly also includes a light modulator assembly in optical communication with the multi-mirror ring-field type lens assembly.
The accompanying drawings illustrate various embodiments of the present apparatus and method and are a part of the specification. The illustrated embodiments are merely examples of the present apparatus and method and do not limit the scope of the disclosure.
Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.
Display optics are provided herein for use in display systems, such as projection televisions, projectors, and the like. In particular, according to several exemplary embodiments discussed herein, the projection assembly includes a multi-mirror ring-field type projection lens. Such projection lens may provide cost and weight reduction. Further, multi-mirror ring-field type projection lenses may provide a high degree of wave-front correction and distortion correction, thereby providing for high quality displayed images.
Several projection assemblies will be discussed below. A projection assembly that includes a compact four mirror ring-field type projection lens in an all-reflective configuration will first be discussed, followed by a discussion of a compact four mirror ring-field type projection lens that includes a compound refractive lens, and a discussion of other types of projection lenses. As used herein, a compact configuration shall be understood broadly to mean lens configuration with a length of about 300 mm. Long throw shall be broadly understood to mean a projection configuration in which the distance to the screen relative to the diameter of the screen has a ratio of about 3:1. Similarly, short throw shall be broadly understood to mean a projection configuration in which the distance to the screen relative to the diameter of the screen has a ratio of about 1:2.
In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present apparatus. It will be apparent, however, to one skilled in the art that the present method and apparatus may be practiced without these specific details. Reference in the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearance of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.
Display System
The image processing unit (110) performs various functions including controlling a spatial light modulator assembly (130). The light source module (140) directs light toward the spatial light modulator assembly (130). The spatial light modulator assembly (130) includes one or more arrays of light modulator devices. The light modulator devices may be in the form of micro-electro mechanical (MEMS) devices, or pixels, which are configured to modulate light incident thereon. The display optics (150) direct the modulated light onto a display surface to form an image.
According to several exemplary embodiments discussed below, the display optics (150) includes a plurality of mirrors. These mirrors are configured to reflect and magnify the modulated light and to display the light onto a viewing surface. The viewing surface may be, but is not limited to, a screen, television, wall, liquid crystal display (LCD), or computer monitor.
Projection Assembly
According to the present exemplary embodiment, the first, second, third, and fourth mirrors (210, 215, 220, 225) are located to one side of the light modulator panel (205). For ease of reference only, the display surface will be referred to as the front. Thus, according to the exemplary embodiment illustrated in
Light modulated by the light modulator panel (205) is directed to the display optics. The ring field width of the display optics may be sufficient to cover the light modulator panel (205), which according to the present exemplary embodiment may be between about 20-30 mm. The display optics may also have a numerical aperture in a range of about 0.1 to 0.2 or greater and an F number within a range of about 2.5 to about 5.0, such as an F number of approximately 3.5. These characteristics may provide a magnification of the output of the light modulator panel (205) of approximately between 20 and 100 times, such as a magnification of about 70 times at a distance of about one meter from the light modulator panel (205). One exemplary mirror assembly will now be described in more detail.
The projection assembly (200) according to the present exemplary embodiment includes a total internal reflection prism (TIR prism) (230). Incoming light (232) is directed to the TIR prism (230). The TIR prism (230) directs the incoming light (232) to the light modulator panel (205). The TIR prism (230) may include a first and second internal reflection interfaces or may only include a first internal reflection surface. For the case of two internal reflection surfaces, the first and second internal reflection interfaces intersect, such that an “X” is formed. The first internal reflection interface directs the light (232) to the light modulator panel (205). The second internal reflection interface may direct light away from the projection lens.
The light modulator panel (205) according to the present exemplary embodiment may be a reflective-type light modulator panel that modulates the incoming light (232) to form display light (235) and non-display light (240). The TIR prism (230) spatially separates the display light (235) and the non-display light (240). In particular, according to the present exemplary embodiment, display light is transmitted through the first and second internal reflection interfaces while non-display light is reflected off the second internal reflection interface and directed away from the display optics. For example, the non-display light may be directed to a beam dump.
The beam dump reduces or minimizes the possibility that the non-display light (240) will reach display optics. According to one exemplary embodiment, the beam dump includes a light-absorbing surface that is shaped to trap and absorb light that is incident thereon. By absorbing substantially all of the non-display light (240) that is incident thereon, the beam dump reduces or minimizes the possibility that the non-display light (240) will reach the display optics. As a result, directing the non-display light (240) away from the projection lens and to the beam dump may increase the contrast ratio of the projection assembly (200).
As introduced, display light (235) from the light modulator panel (205) is directed to the display optics. In particular, the display light (235) is first incident on the first mirror (210). The first and second mirrors (210, 215) may form a Schwarzschild-type system. Accordingly, the first mirror (210) may be a concave mirror with a radius of curvature of about 165 mm, a maximum aspheric departure of about 9 μm, and a conic constant (k) of about 0.189 mm. In general, aspheric departure refers to the divergence of the shape of an actual mirror as compared to a sphere with a given radius of curvature. The position and shape of the first mirror (210) are such that light reflected from the first mirror (210) is directed to the second mirror (215).
As introduced, the first and second mirrors (210, 215) may operate as a Schwarzchild-type lens. Accordingly, the second mirror (215) according to the present exemplary embodiment may be a convex mirror with radius of curvature of about 140 mm, a maximum aspheric departure of about 9 μm, and a conic constant (k) of about 1.25 mm. Additionally, according to one exemplary embodiment, the second mirror (215) may be coupled to wobulation control.
The first sub-frame (300) and the second sub-frame (400) each comprise a data array of a subset of the image data for the corresponding image frame. In particular, the first and second sub-frames (300, 400) each include a plurality of pixels (305). Although the exemplary image processing unit (110;
In one embodiment, as illustrated in
In alternative embodiments, the first sub-frame (300) and the second sub-frame (400) may only be offset in either the vertical direction or in the horizontal direction. In the illustrated embodiment, the second mirror (215) is configured to offset the beam of light between the second mirror (215) and the display optics (150;
As illustrated in
Thus, by generating a first and second sub-frame (300, 400) and displaying the two sub-frames in the spatially offset manner as illustrated in
In addition, the display system (100;
Thus, as shown by the examples in
In addition, by overlapping pixels of image sub-frames, the display system (100;
Referring again to
The light reflected to the display surface from the fourth mirror (225) may have a net magnification of between about 20 to 100, such as a magnification of about 70. Further, the display optics may provide accurate reproduction of the output of the light modulator panel (205). Thus far, one exemplary projection assembly (200) has been discussed. Those of skill in the art will appreciate that other configurations are possible.
In addition, the mirrors may be arranged in other configurations. For example, according to one exemplary embodiment illustrated in
According to such an exemplary embodiment, the lens assembly (200-2) also includes first, second, and third mirrors (210-2, 215-2, and 220-2 respectively). The first mirror (210-2) of the present exemplary long-throw configuration is a concave mirror with a radius of curvature of about −160 mm, a maximum aspheric departure of about 22 μm, and a conic constant of about 0.3 mm. The second mirror (215-2) according to the present exemplary embodiment is a convex mirror with a radius of curvature of about −300 mm, a maximum aspheric departure of about 7 μm, and a conic constant of about 10.74 mm. The third mirror (220-2) according to the present exemplary embodiment is a concave mirror with a radius of curvature of about −600 mm, a maximum aspheric departure of about 232 μm, and a conic constant of about 16.25 mm. The fourth mirror (225-2) according to the present exemplary embodiment is a convex mirror with a radius of curvature of about 960 mm, such as a radius of curvature of about 962.79 mm, a maximum aspheric departure of about 880 μm, and a conic constant of about 58 mm. Such a system may provide wavefront correction of better than about 1/20 wave and distortion of less than about 0.5% across the displayed image.
Compact four mirror ring field-type lenses have been discussed herein. Those of skill in the art will appreciate that other configurations may also be used. These configurations include, without limitation, experimental test stand (ETS), small angle design, and symmetric type four mirror ring field-type lenses. Further, the exemplary embodiments discussed thus far have made use of four mirrors. Those of skill in the art will appreciate that any number of mirrors may be utilized, including five, six, or more mirrors.
In conclusion, assemblies are provided herein for use in display systems, such as projection televisions, projectors, and the like. In particular, according to several exemplary embodiments discussed herein, the projection assembly includes a multi-mirror ring field-type projection lens. Such projection lens may provide cost and weight reduction. Further, multi-mirror ring field-type projection lenses may provide a high degree of wave front correction and distortion correction, thereby providing for high quality displayed images.
The preceding description has been presented only to illustrate and describe the present method and apparatus. It is not intended to be exhaustive or to limit the disclosure to any precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the disclosure be defined by the following claims.
