Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2000-03-07
2004-03-02
Hjerpe, Richard (Department: 2674)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S088000, C345S090000, C345S103000, C345S001100, C345S001300, C345S067000, C345S698000, C345S094000, C348S383000
Reexamination Certificate
active
06700557
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to display technologies.
BACKGROUND
Improvements in portable electronics has led to new designs that support low power consumption and miniature device sizes. In conjunction with the advent of improved portable electronics, light weight and low power displays are also being developed. Accordingly, the combination of smaller portable electronics and new displays has resulted in a variety of miniature display devices with a multitude of applications.
Prior art miniature display devices use miniaturized cathode ray tubes to display images. Cathode ray tubes, however, create numerous disadvantages. One disadvantage results from the power requirements of the cathode ray tube. In particular, a cathode ray tube typically includes an electrode beam that requires a large amount of power. To facilitate the large power requirements, extraneous power supplies are typically attached to the exterior of the miniature display device. The extraneous power supply, however, reduces the portability of the miniature display device.
Another disadvantage of using cathode ray tubes in miniature display devices results from the size requirements of the cathode ray tube. The design characteristics of cathode ray tubes requires minimum sizing of components. Specifically, the electrode beam used to generate images in the cathode ray tube must have a minimum displacement from the screen area of the cathode ray tube. Accordingly, the size requirements of the cathode ray tube make the cathode ray tube (CRT) impractical for use in most miniature display devices. For example, in miniature displays (such as head-mounted displays) where a wide range of peripheral vision and mobility is required the power and size requirements of cathode ray tubes make the use of cathode ray tubes impractical.
Spatial light modulators, such as liquid crystal displays, do not have many of the disadvantages of CRTs. Liquid crystal displays create an image by using an electric field to control the transmission of light through a liquid crystal.
FIG. 1
illustrates a prior art liquid crystal display. In particular, cell
100
shows a reflective liquid crystal display (“LCD”). Cell
100
includes a liquid crystal layer,
130
, coupled between layer
105
, layer
150
, and four mechanical borders. For illustrative purposes only two mechanical borders, spacer
110
and spacer
140
, are shown. The mechanical borders are used to maintain a predetermined space between layer
105
and layer
150
. Accordingly, layers
105
and
150
in conjunction with the four mechanical borders are used to contain liquid crystal layer
130
and maintain the structural integrity of cell
100
.
Cell
100
uses incident light, light source
105
, to generate an image on layer
155
. In one particular example of cell
100
, light source
105
is polarized before it passes through layer
155
and enters liquid crystal
130
with a polarization plane at 45° to liquid crystal
130
's molecular orientation. Subsequently, the polarized light is reflected on mirror
120
and returns through layer
155
. In this example, the reflected light is transmitted through an analyzing polarizer as long as the polarization of the light is changed by the liquid crystal layer
130
.
To generate an image, cell
100
changes the polarization of light passing through an area within liquid crystal
130
. In particular, cell
100
includes a single transparent control electrode, layer
150
made from indium tin oxide. Cell
100
also includes an array of pixel electrodes (which may themselves form the mirror
120
). Each electrode of the array of pixel electrodes, electrode
115
, corresponds to a pixel of a generated image.
For example, to generate a single pixel image, cell
100
applies a voltage between a particular pixel electrode
115
and layer
150
using pixel electrode logic (not shown) and driver circuitry (not shown). The voltage difference between electrode
115
and layer
150
creates an electric field across liquid crystal layer
130
. The field, in turn, changes the orientation of the molecules located in the liquid crystal
130
, thus changing the polarization of light passing through the liquid crystal subjugated to the field. Accordingly, the changed polarized region of the liquid display layer
130
allows light from light source
105
to traverse from the mirror
120
across cell
100
and through the output analyzing polarizer (not shown). Thus, the contrast between the darkened and light regions of liquid crystal layer
130
creates the single pixel image on layer
155
.
To generate a color image, cell
100
may use a time sequential color display system. In a time sequential color display system three light sources (e.g., a red light, a green light, and a blue light—i.e. RGB light source) are sequentially illuminated upon liquid crystal layer
130
. Cell
100
also includes synchronizing signals and logic (not show) that coordinate the transition between the different light sources and modulate the voltages applied to the array of transparent pixel electrodes. Using the three light sources, the synchronizing logic, and the synchronizing signals, cell
100
displays color images on layer
155
.
The light weight and low power design characteristics of a liquid crystal display (“LCD”) makes the LCD ideal for use in head-mounted displays. For example, Provisional U.S. Patent Application No. 60/070,216, filed on Dec. 31, 1997, entitled “AN IMAGE GENERATOR HAVING A MINIATURE DISPLAY DEVICE” describes a head-mounted display uses in conjunction with a LCD. Examples of specific LCDs that may be used in miniature display devices may also be found in U.S. patent application Ser. No. 08/801,994, filed on Feb. 18, 1997, entitled “DISPLAY SYSTEM HAVING ELECTRODE MODULATION TO ALTER A STATE OF AN ELECTRO-OPTIC LAYER.” The patent application entitled “DISPLAY SYSTEM HAVING ELECTRODE MODULATION TO ALTER A STATE OF AN ELECTRO-OPTIC LAYER” (Ser. No. 08/801,994, filed on Feb. 18, 1997) is hereby incorporated by reference.
Using a LCD in a head-mounted display provides advantages in terms of weight and power consumption, however, the use of LCDs in head-mounted displays also results in numerous disadvantages. One disadvantage results from the motion of the user wearing the head-mounted display. In particular, when the user's head moves relative to the head-mounted display's magnifying mirrors or lenses the user loses his/her field of vision. Accordingly, the user is unable to determine the circumference or perimeter of the liquid crystal's active display area. The active display area defines the region of the liquid crystal display that is displaying a generated image. The active display area also defines the liquid crystal region and accompanying electrodes used to generate an image. Even when the user's head does not move, the user may not realize that he/she is not seeing the entire active display area.
Another disadvantage results from using software to define an active display area in head-mounted displays. In particular, using software to define an active display area for a head-mounted display requires a specialized operating system. For example, software may place items within windows, and the software may create a border at the edge of the active display area. However, using software to define an active display area requires allocating pixel electrodes to define an active display area. The allocation of electrodes results in a loss of displayable image area.
SUMMARY OF THE INVENTION
A display device operable to generate images and a border image is disclosed. The display device in one example of the invention comprises an electrode structure coupled to a spatial light modulator display layer. The electrode structure is configured to define an active display area. The display of this example also comprises a first electrode surrounding the electrode structure and a second electrode coupled to the spatial modulator display layer. The second electrode is located above the first electrode, and
Abdulselam Abbas
Hjerpe Richard
Ingrassia Fisher & Lorenz PC
Three-Five Systems, Inc.
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