Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2002-12-19
2004-03-23
Lester, Evelyn A. (Department: 2873)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S038000, C345S050000, C345S206000, C349S114000, C359S318000, C359S320000
Reexamination Certificate
active
06710758
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to a spatial light modulator and, more specifically, to a spatial light modulator with improved inter-pixel performance.
2. Technical Background
Reflective liquid crystal (LC) spatial light modulators (SLMs) have been constructed with spatially distributed discrete pixels in one or more dimensions.
FIG. 1
depicts a partial cross-section of a typical prior art SLM
100
, absent a number of common barrier layers, such as silicon nitride (SiN) and silicon dioxide (SiO
2
), which are well known and not particularly relevant to the present discussion and therefore are not illustrated. As is shown in
FIG. 1
, the SLM
100
includes a transparent first substrate
102
, which includes a continuous optically transparent first electrode
106
, formed on an upper surface of the substrate
102
, that serves as a ground electrode. A top and second substrate
104
includes a pixel layer
108
formed on a lower surface, which includes a number of discrete conductive pixel elements
108
A,
108
B and
108
C. A transparent alignment layer
112
is formed over the layer
108
and a transparent alignment layer
116
is formed over the first electrode
106
. The alignment layers
112
and
116
may be made of a polyamide and are used to align LC molecules of electro-optic material
114
.
The pixel elements
108
A-
108
C also function as mirrors and act to reflect an incoming light beam that travels through the electro-optic material
114
, e.g., a liquid crystal (LC) film, interposed between the layer
108
and the electrode
106
, when a potential difference applied between one of the pixel elements
108
A-
108
C and the first electrode
106
is such that the electro-optic material
114
in the area of at least one of the pixel elements
108
A-
108
C is transmissive.
The pixel element
108
A is separated from the pixel element
108
B by an inter-pixel region
110
A and the pixel element
108
B is separated from the pixel element
108
C by an inter-pixel region
110
B. With reference to a center of the pixel element
108
B, it will be appreciated that due to electrical field fringing and the absence of an electrode material, the optical properties (e.g., insertion loss) of the inter-pixel regions
110
A and
110
B will differ from that of the center of the pixel element
108
B.
FIG. 2
depicts a graph illustrating a typical insertion loss associated with the SLM
100
of FIG.
1
. As shown in
FIG. 2
, the insertion loss attains a maximum loss at points
120
and
122
, which correspond to inter-pixel regions
110
B and
110
A, respectively. As is also illustrated at points
124
,
126
and
128
, the respective insertion losses associated with the pixel elements
108
A,
108
B and
108
C is less than the insertion loss associated with the inter-pixel regions
110
A and
110
B.
In many applications, the difference in the optical properties between a center of a pixel element and an inter-pixel region is not critical and inter-pixels regions can simply be masked with an absorbing material. However, in a number of applications, it is desirable for the inter-pixel regions to have optical properties, which are similar to that of the pixel element centers. For example, when channels are banded to produce a continuous spectrum it is desirable for the inter-pixel regions of an SLM to have the same characteristics as the pixel element centers.
Thus, a spatial light modulator (SLM) whose inter-pixel regions have optical properties that are substantially similar to the optical properties of pixel element centers is desired.
SUMMARY OF THE INVENTION
One embodiment of the present invention is directed to a reflective spatial light modulator (SLM) that includes a first substrate, a second substrate and an electro-optic material positioned between the first and second substrates. According to one embodiment, the first substrate includes a continuous reflective ground layer that acts as a first electrode and the second substrate is transparent and includes a pixel layer having a plurality of pixel elements formed in a pattern. The pixel elements are formed of a transparent conductive material and are separated by inter-pixel regions formed of a non-conductive material. A transmissivity of the electro-optic material in a vicinity of each of the plurality of pixel elements is controlled by a potential difference applied between the first electrode and a respective one of the pixel elements.
According to another embodiment of the present invention, a reflective SLM includes an optically transparent first substrate, a second substrate, an electro-optic material positioned between the first and second substrates and a dielectric mirror. The first substrate includes a ground layer that acts as a continuous transparent first electrode. The second substrate includes a pixel layer having a plurality of pixel elements formed in a pattern. The pixel elements are formed of a conductive material and are separated by inter-pixel regions formed of a non-conductive material. The transmissivity of the electro-optic material in a vicinity of each of the plurality of pixel elements is controlled by a potential difference applied between the first electrode and a respective one of the pixel elements. The dielectric mirror is positioned between the pixel layer and the electro-optic material.
Additional features and advantages of the invention will be set forth in the detailed description which follows and will be apparent to those skilled in the art from the description or recognized by practicing the invention as described in the description which follows together with the claims and appended drawings.
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Caracci Lisa A.
Kondis John P.
Lindquist Robert G.
Ma Rui-Qing
Reisin Carina R.
Bean George V.
Corning Incorporated
Lester Evelyn A.
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