Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1999-02-26
2002-05-07
Hjerpe, Richard (Department: 2674)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S087000, C361S689000
Reexamination Certificate
active
06384809
ABSTRACT:
BACKGROUND
The invention relates to a projection system, such as a liquid crystal display (LCD) projection system, for example.
Referring to
FIG. 1
, a reflective liquid crystal display (LCD) projection system
5
typically includes an LCD display panel (LCD display panels
22
,
24
and
26
, as examples) for each primary color that is projected onto a screen
10
. In this manner, for a red-green-blue (RGB) color space, the projection system
5
may include an LCD display panel
22
that is associated with the red color band, an LCD display panel
24
that is associated with the green color band and an LCD display panel
26
that is associated with the blue color band. Each of the LCD panels
22
,
24
and
26
modulates light from a light source
30
to form red, green and blue images, respectively, that add together to form a composite color image on the screen
10
. To accomplish this, each LCD display panel
22
,
24
or
26
receives electrical signals that indicate the corresponding modulated beam image to be formed.
More particularly, the projection system
5
may include a beam splitter
14
that directs a substantially collimated white beam
11
of light (provided by the light source
30
) to optics that separate the white beam
11
into red
13
, blue
17
and green
21
beams. In this manner, the white beam
11
may be directed to a red dichroic mirror
18
that reflects the red beam
13
toward the LCD panel
22
that, in turn, modulates the red beam
13
. The blue beam
17
passes through the red dichroic mirror
18
to a blue dichroic mirror
20
that reflects the blue beam
17
toward the LCD display panel
26
for modulation. The green beam
21
passes through the red
18
and blue
20
dichroic mirrors for modulation by the LCD display panel
24
.
For reflective LCD display panels, each LCD display panel
22
,
26
and
24
modulates the incident beams, and reflects the modulated beams
15
,
19
and
23
, respectively, so that the modulated beams
15
,
19
and
23
return along the paths described above to the beam splitter
14
. The beam splitter
14
, in turn, directs the modulated beams
15
,
19
and
23
through projection optics, such as a lens
12
, to form modulated beam images that ideally overlap and combine to form the composite image on the screen
10
.
The optical performance of the LCD display panel
22
,
24
or
26
may be a function of the temperature of the display panel
22
,
24
or
26
, and the temperature of the display panel
22
,
24
or
26
may rise during operation due to the heating caused by the illumination of the display panels
22
,
24
and
26
. Thus, the optical performance of the display panels
22
,
24
and
26
may also vary during operation. To compensate for thermal drift, the projection system
5
may have a user “contrast” control to adjust the timing of voltages that are applied to the display panels
22
,
24
and
26
to form the modulated beam images. However, the temperature of each display panel
22
,
24
or
26
may be too high for the timing adjustment to adequately compensate the display panels
22
,
24
and
26
.
An alternative way to adjust for thermal drift is to apply correcting voltages to drive circuits that form the images on the display panels
22
,
24
and
26
in response to a user control. However, unfortunately, this approach may also be ineffective once the temperature of the display panel exceeds an optimal range of temperatures.
Another way to compensate for thermal drift is to lower the temperatures inside the projection system
5
, by for example, reducing the heat that is associated with the light beams that illuminate the display panels
22
,
24
and
26
. However, unfortunately, such techniques may impede the performance of the projection system
5
. For example, a dichroic infrared (IR) filter may be used to filter infrared light, a source of heat, from the white beam
11
so that the amount of heat that reaches the display panels
22
,
24
and
26
is reduced. However, a dichroic IR filter may have bandstop characteristics which are a function of an angle of incidence of the beam
11
, and as a result, the imaging of the beam from the light source
30
may need to be very precise, a condition that may increase the cost of the projection system
5
. Furthermore, increasing the accuracy of the imaging of the light source
30
may increase the imaging of defects in the light source
30
itself. Also, to remove enough heat, the IR dichroic filter may have a high bandstop frequency and thus, remove a deep red band of colors from the beam
11
. Unfortunately, the removal of the deep red band of colors may degrade the color reproduction accuracy of the system
5
.
Thus, there is a continuing need to address one or more of the problems stated above.
SUMMARY
In one embodiment of the invention, a projection system includes a light source, a display panel, a temperature gradient panel and a controller. The light source is adapted to generate a first beam of light, and the display panel is adapted to modulate at least a portion of the first beam of light to form an associated modulated beam of light. The temperature gradient panel is thermally coupled to the display panel, and the controller is electrically coupled to the temperature panel and the display panel. The controller is adapted to control the temperature gradient panel to regulate a temperature of the display panel.
In another embodiment, a computer system includes a processor, a display panel, a temperature gradient panel and a controller. The processor is adapted to furnish a first indication of an image. The display panel is adapted to modulate at least a portion of the first beam of light to form an associated modulated beam of light in response to the first indication of the image. The temperature gradient panel is thermally coupled to the display panel, and the controller is electrically coupled to the temperature gradient panel and the display panel. The controller is adapted to control the temperature gradient panel to regulate a temperature of the display panel.
In yet another embodiment, a method includes generating a first beam of light and modulating at least a portion of the first beam of light with a display panel to form an associated modulated beam of light. A temperature gradient is established near the display panel, and the temperature gradient is regulated to control the temperature of the display panel.
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patent: 5255109 (1993-10-01), Klein
patent: 5313362 (1994-05-01), Hatada et al.
patent: 5500054 (1996-03-01), Goldstein
patent: 5598320 (1997-01-01), Toedtman et al.
patent: 5606341 (1997-02-01), Aguilera
patent: 6072459 (2000-06-01), Asakawa et al.
patent: 6121950 (2000-09-01), Zavracky et al.
patent: 6188571 (2001-02-01), Roganti et al.
patent: 6125006 (2001-07-01), Yamamoto et al.
patent: 6275945 (2001-08-01), Tsuji et al.
patent: 6288896 (2001-09-01), Hsu
Hjerpe Richard
Nguyen Kimnhung
Trop Pruner & Hu P.C.
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