Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2002-10-18
2004-11-30
Chowdhury, Tarifur R. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C359S619000, C257S232000
Reexamination Certificate
active
06825898
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a lens array substrate and a liquid crystal display. Particularly, the invention relates to the liquid crystal display and the lens array substrate used for the above display which is used in a projector.
BACKGROUND OF THE INVENTION
A transmissive liquid crystal display mainly comprises a liquid crystal panel and a power source device (back light).
FIG. 1
is an exploded perspective view that schematically shows the inner structure of a liquid crystal display panel
1
. The transmissive liquid crystal display panel
1
comprises a back substrate
2
, a front substrate
3
, and a liquid crystal layer
4
which is sealed therebetween. The back substrate
2
comprises pixel electrodes
6
and TFTs (thin film transistor)
7
formed for each pixel region on the surface of a glass substrate
5
, and an orientation film
8
is formed on the pixel electrodes and TFTs. In the front substrate
3
, color filters
10
for red (R), green (G) and blue (B) are formed on the back surface of a glass substrate
9
, a transparent electrode (ITO)
11
is formed to cover the back surfaces of all the color filters, and an orientation film
12
is formed on the transparent electrode
11
. The liquid crystal layer
4
is filled in a space formed between the orientation film
12
on the front substrate
3
and the orientation film
8
on the back substrate
2
, and the periphery of the liquid crystal layer
4
is sealed with a sealing spacer (not shown). The back surface of the back substrate
2
and the front surface of the front substrate
3
have polarizing plates
13
and
14
, respectively on the opposite sides.
Light is emitted by a light source device from the back of the liquid crystal display panel
1
, and ON/OFF state of the voltage applied to each pixel electrode
6
and the transparent electrode
11
is controlled by the TFTs
7
, to control the transmission and the blocking of the light in each pixel on the liquid crystal display panel
1
, in order to generate an image.
In the liquid crystal display panel
1
, the gaps between the color filters
10
are covered with black matrixes
15
to prevent the light from the light source from passing through the gaps, in order to improve the contrast in an image for a sharp image. The black matrixes
15
are made from a light-absorbing resin or a chromium film. The matrixes
15
are formed by printing, deposition or sputtering, then patterns are formed thereon by the photolithography.
On the other hand, the liquid crystal display is used in commercially available presentation tools such as a liquid crystal projector, as well as used as a display section of a personal computer (PC), a personal digital assistant (PDA), and a mobile phone. Particularly, the liquid crystal projector is commonly used as a projector for presentation in a meeting, or as a digital cinema.
FIG. 2
illustrates the construction of a color liquid crystal projector
21
. A light source device
22
such as a halogen lamp having a reflector is provided with a dichroic mirror
23
in front of the device
22
at an angle of 45°, which transmits only blue light
34
B while reflects red light
34
R and green light
34
G. In the direction to which the light passed through the dichroic mirror
23
proceeds, a total reflection mirror
24
is provided at an angle of 45°, and in the direction to which the light reflected by the total reflection mirror
24
proceeds, a liquid crystal display panel
25
for single color for generating a blue image is provided, which, in turn faces the side surface of a prism
26
having reflective surfaces in two directions. In the direction to which the light reflected by the dichroic mirror
23
proceeds, a dichroic mirror
27
which reflects green light
34
G while transmits red light
34
R is provided at an angle of 45°, and in the direction to which the light reflected by the dichroic mirror
27
proceeds, a liquid crystal display panel
28
for single color for generating a green image is provided, which, in turn faces the back surface of the prism
26
. In the direction to which the light passed through the dichroic mirror
27
proceeds, a total reflection mirror
29
is provided at an angle of 45°, and in the direction to which the light reflected by the total reflection mirror
29
proceeds, a total reflection mirror
30
is provided at an angle of −45°, and in the direction to which the light reflected by the total reflection mirror
30
proceeds, a liquid crystal display panel
31
for single color for generating a red image is provided, which, in turn faces another side surface of the prism
26
. A projection lens
32
is provided on the front surface of the prism
26
.
In the white light emitted from the light source device
22
, blue light
34
B passes through the dichroic mirror
23
, reflected by the total reflection mirror
24
, then incident on the liquid crystal display panel
25
. When the blue light irradiates on the liquid crystal display panel
25
, the light passed through the liquid crystal display panel
25
generates a blue image, which, in turn, is reflected to the forward direction by the reflection surface of the prism
26
. In the white light emitted from the light source device
22
, green light
34
G is reflected by the dichroic mirror
23
, reflected by the dichroic mirror
27
, then incident on the liquid crystal display panel
28
. When the green light
34
G irradiates on the liquid crystal display panel
28
, the light passed through the liquid crystal display panel
28
generates a green image, which, in turn, passes through the prism
26
. In the white light emitted from the light source device
22
, red light
34
R is reflected by the dichroic mirror
23
, passes through the dichroic mirror
27
, reflected by the total reflected mirrors
29
and
30
, then incident on the liquid crystal display panel
31
. When the red light
34
R irradiates on the liquid crystal display panel
31
, the light passed through the liquid crystal display panel
31
generates a red image, which, in turn, is reflected to the forward direction by the reflection surface of the prism
26
.
Thus, the blue image generated on the liquid crystal display panel
25
, the green image generated on the liquid crystal display panel
28
, and the red image generated on the liquid crystal display panel
31
are superimposed by the prism
26
to make a color image, which, in turn is projected on the projection lens
32
. The color image passed through the projection lens
32
is focused on the front screen
33
. The front screen
33
thus display the color image.
In this technical field, there is a need for a smaller projector having higher luminance in order to improve the usability and the quality of an image. Also, there is a need for a liquid crystal projector and a personal computer to have higher resolution. In response, the number of the pixels on the liquid crystal display panel is expanding. However, even if a pixel is reduced in size in order to increase its number, it is difficult to reduce the size of the TFT and its wiring in each pixel. The ratio of the pixel open area (open area ratio) gets lower as the area of a pixel is reduced for increased number of the pixels. Therefore, in order to keep the luminance of the screen even when the open area ratio is reduced, it is necessary to increase the amount of the light from the light source device.
Thus, the light source device of a liquid crystal display apparatus for a liquid crystal projector and an image display emits more and more amount of the light. However, when the light emitted from light source device increases, the light irradiating on the TFTs and their wirings increases accordingly, so that carriers are prone to be excited by the light, which may lead to unstable operation or malfunction of the TFT.
In order to improve the efficiency of the light while suppressing the increase in the light supplied from the light source device, a lens array is provided on the back substrate.
FIG. 3
is a cross-sectional view that schem
Kobayashi Keiji
Kurata Gouo
Miyamoto Hiroyuki
Nishizaki Osamu
Akkapeddi P. R.
Chowdhury Tarifur R.
Omron Corporation
Osha & May L.L.P.
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