Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1998-05-04
2001-03-20
Hjerpe, Richard A. (Department: 2774)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S032000, C345S082000, C345S031000, C340S815420, C340S815450, C340S815540, C340S815680
Reexamination Certificate
active
06204832
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to scanning display methods and apparatus, and more particularly to a scanning display including an array of optical elements, such as microlenses.
Small, light weight displays are desirable for use in portable devices such as cellular phones, pagers, handheld computers and helmet-mounted displays. One challenge to implementing a small lightweight display is the typically poorer resolution achieved relative to that of a full size computer screen display. A scanned beam display such as the virtual retinal display disclosed in U.S. Pat. No. 5,467,104 to Furness et al, which is incorporated herein by reference, is able to achieve improved resolution while being of a relatively small volume.
A scanned retinal display device is an optical device that produces a preceived image by scanning a modulated beam of light onto the retina of an eye. In one such device, light is emitted from a light source, passed through a lens, then deflected along a scan path by a scanning device. At a distance defined by the lens, the scanned light converges to a focal point for each pixel position. As the scanning occurs the focal point moves to define an intermediate image plane. The light then diverges beyond the plane. An eyepiece typically is positioned along the light path beyond the intermediate image plane at some appropriate position. The eyepiece receives light that is being deflected along a raster pattern and redirects the beam to define an “exit pupil.” The exit pupil occurs shortly beyond the eyepiece in an area where a viewer's eye pupil is to be positioned. When a viewer looks into the eyepiece to view an image, the viewer's eye pupil receives the light at differing angles at different times during the scanning cycle. This range of angles determines the size of the image perceived by the viewer. Modulation of the light during the scanning cycle determines the content of the image.
The scanned retinal display typically places significant demands upon the scanning system, in terms of field of view, speed of the scanning mirror, size, temperature dependence, and a variety of other performance and design parameters. Often, scanned beam systems meet these demands with scanned mirrors that move at high angular rates. While scanned mirror display systems can perform well, it is sometimes desirable to develop alternative approaches to producing displays using scanned beams, particularly in light weight, small volume displays. As disclosed herein, an approach to producing such an image includes display that generates an image upon a screen or viewer's eye using a microlens array and a light source array.
SUMMARY OF THE INVENTION
According to one embodiment of the invention, an array of light emitters, such as a point source array, generates an array of output beams defining a plurality of image pixels. An array of optical elements, such as microlenses, receives the output beams and directs them toward desired pixel locations. Either one or both of the emitter array and the microlens array are scanned over time to form an image of pixels.
According to one aspect of the invention, an image or a subsection of an image is composed of an array of image portions. Each image portion includes a plurality of pixels. For each image portion, there is a corresponding point source of light within the point source array and a corresponding microlens within a microlens array. The corresponding point source and microlens scan within a given image portion to generate all of the pixels within that image portion. Each point source within the point source array is fixed relative to each of the other point sources within the point source array. Similarly, each of the microlenses is fixed relative to the other microlenses within the microlens array. Thus, as one microlens is scanned relative to its corresponding point source to generate the multiple pixels within one image portion, the other microlenses, concurrently, are being scanned relative to the other point sources to generate the multiple pixels within each of the other image portions. Each of the point source-microlens combinations completes the scan of its corresponding image portion at the same time. Upon completion, the image or image subsection has been completely scanned, allowing a viewer to perceive the image or image subsection. In the case of completion of an image scan, an image frame has been completed. A new image frame then may be scanned. In the case of completion of an image subsection, the entire point source array-microlens array combination then can be repositioned to scan another image subsection. When all image subsections have been scanned an image frame is complete. A new frame may then commence.
According to various applications, either or both of the point source array and the microlens array may be a one-dimensional array or a two dimensional. For full image scanning with one dimensional arrays, one element of each array corresponds to each pixel in a line of an image (e.g., a horizontal line or a vertical line). For example, for a microlens-point source combination where each microlens-point source pair corresponds to a pixel in a vertical line of an image, the microlens-point source combination produces a vertical line of image pixels simultaneously. Scanning the microlens array relative to the point source array scans the vertical line of output beams horizontally to scan the image. Alternatively, such a scan may be for only an image subsection. The arrays then are repositioned to scan another image subsection.
For full image scanning with two dimensional arrays, one microlens-point source combination corresponds to each image portion of the full image. The microlens array is scanned relative to the point source array in either one dimension or two dimensions to generate all of the pixels within each image portion. For full image subsection scanning with two dimensional arrays one microlens-point source combination corresponds to each image portion of the image subsection. The microlens array scans relative to the point source array in either one dimension or two dimensions to generate all of the pixels within each image portion of the image subsection.
According to another aspect of this invention, a drive circuit moves the microlens array along one or two drive axes. In one embodiment, the drive circuit includes electromagnetic coils that move a plate in which the lenses are integrally formed. In another embodiment, the drive circuit includes piezoelectric volumes which deform to deflect plate in which the lenses are integrally formed.
Alternatively, the point source array is moved rather than the microlens array. One set of piezoelectric volumes moves the array along one axis for scanning in a first direction. Another set of piezoelectric volumes is included in some embodiments to move the array along another axis for scanning in a second direction.
According to another aspect of this invention, a second array of microlenses is included in some embodiments for two dimensional scanning of the output beams. One microlens array is moved along one scanning axis. The other microlens array is moved along the other scanning axis. Drive circuits are included to move the respective microlens arrays.
According to another aspect of the invention, a display apparatus presents an image including a plurality of image portions. Each one of the plurality of image portions includes a plurality of image pixels. A plurality of light emitters are operative with each one light emitter emitting a beam of light in response to an input signal. Each one microlens of a corresponding plurality of microlenses receives a beam of light from its corresponding light emitter. Each one microlens, the corresponding light emitter and the corresponding emitted, received and passed beam of light together correspond to one image portion of the image. The microlens array is movable through a plurality of positions relative to the plurality of light emitters to scan each beam of light through each image p
Johnston Richard S.
Melville Charles D.
Tidwell Michael
Hjerpe Richard A.
Koda Steven P.
University of Washington
Zamani Ali A.
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