CA2125098A1 - Liquid crystal display panel and liquid crystal projector employing the same - Google Patents
Liquid crystal display panel and liquid crystal projector employing the sameInfo
- Publication number
- CA2125098A1 CA2125098A1 CA002125098A CA2125098A CA2125098A1 CA 2125098 A1 CA2125098 A1 CA 2125098A1 CA 002125098 A CA002125098 A CA 002125098A CA 2125098 A CA2125098 A CA 2125098A CA 2125098 A1 CA2125098 A1 CA 2125098A1
- Authority
- CA
- Canada
- Prior art keywords
- liquid crystal
- light
- display panel
- crystal display
- lenses
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/133526—Lenses, e.g. microlenses or Fresnel lenses
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N9/00—Details of colour television systems
- H04N9/12—Picture reproducers
- H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F2201/00—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00
- G02F2201/40—Arrangements for improving the aperture ratio
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- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- Mathematical Physics (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Liquid Crystal (AREA)
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Projection Apparatus (AREA)
Abstract
bstract of the Disclosure A liquid crystal display panel and a liquid crystal projector employing the same, the panel having a light converging device on its light receiving side and a light compensating means on its light emitting side. The converging device compensates for the output light rays having been diverged or converged en route to a projection lens system so as to render the output light rays parallel. This enhances the effective pixel aperture ratio by converging incident light rays onto a pixel and also minimizes the volume of the projection lens system.
[ FIG. 5 ]
[ FIG. 5 ]
Description
212~09~
LIQUID CRYSTAL DISPLAY PANEL AND
LIQUID CRYSTAL PROJECTOR EMPLOYING THE SAME
Background of the Invention The present invention relates to a liquid crystal display panel and a projector employing the same, and more particularly, to a liquid crystal display panel having an improved effective pixel aperture ratio and a liquid crystal projector having a reduced diameter projection lens system.
A general liquid crystal projector is used to produce an image utilizing a liquid crystal display panel for controlling transmitted light, and then to project the thereby produced image onto a projection screen for viewiny. Such a projector, as shown in Fig.1, includes a parabolic reflection mirror 2 for reflecting light emitted from a light source 1, a liquid crystal display panel 3 disposed along an optical axis 9 of the light reflected by the reflection mirror 2 and driven by a driving circuit 8, polarizing plates 4 and 5 respectively .i located in front of and in back of the liquid crystal display panel 3 for polarizing light passing through the liquid crystal display panel 3, and a projection lens system 6 disposed along the optical axis of the light transmitted ~ .
i through liquid crystal display panel 3 for projecting an ` enlarged image onto a projection screen 7.
` Reflection mirror 2 reflects the light rays emitted from light source 1 to render them parallel to the optical axis 9 so as to form parallel source light. Liquid crystal display ~..
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LIQUID CRYSTAL DISPLAY PANEL AND
LIQUID CRYSTAL PROJECTOR EMPLOYING THE SAME
Background of the Invention The present invention relates to a liquid crystal display panel and a projector employing the same, and more particularly, to a liquid crystal display panel having an improved effective pixel aperture ratio and a liquid crystal projector having a reduced diameter projection lens system.
A general liquid crystal projector is used to produce an image utilizing a liquid crystal display panel for controlling transmitted light, and then to project the thereby produced image onto a projection screen for viewiny. Such a projector, as shown in Fig.1, includes a parabolic reflection mirror 2 for reflecting light emitted from a light source 1, a liquid crystal display panel 3 disposed along an optical axis 9 of the light reflected by the reflection mirror 2 and driven by a driving circuit 8, polarizing plates 4 and 5 respectively .i located in front of and in back of the liquid crystal display panel 3 for polarizing light passing through the liquid crystal display panel 3, and a projection lens system 6 disposed along the optical axis of the light transmitted ~ .
i through liquid crystal display panel 3 for projecting an ` enlarged image onto a projection screen 7.
` Reflection mirror 2 reflects the light rays emitted from light source 1 to render them parallel to the optical axis 9 so as to form parallel source light. Liquid crystal display ~..
.
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2~2.~098 ~anel 3 blocks or transmits the incident source light according to an image forming signal from driving circuit 8 so as to form a light image made up of pixel units. To control the polarization of the incident light on liqllid crystal display panel 3 and the light output through liquid crystal display panel 3, polarizing plates 4 and 5 transmit only the light polarized in a predetermined orientation. The two polarizing plates 3 and 4 are so placed that a polarizing axis thereof maintains a predetermined angle. Projection lens system 6 projects the light image obtained from liquid crystal panel 3 so as to form an intended image on the screen 7.
In order to obtain a bright image in such a liquid crystal projector, it is required to maximize an effective pixel aperture ratio of the liquid crystal display panel 3. A
i 15 conventional general liquid crystal display panel makes use of a thin film transistor (TFT) as its pixel switching element.
Referring to Fig.2, first and second substrates 31 and 32 are arranged to be spaced apart by a predetermined distance.
Liquid crystal 33 fills the space between the first and second substrates 31 and 32. A driving means for driving each pixel of the liquid crystal display panel 3 is provided on the respective internal surfaces of first and second substrates 31 and 32. A plurality of pixel electrodes 322 for driving liquid crystal 33 in a predetermined pixel pattern and TFTs 321 serving as the switching element of the driving means of the corresponding pixel are placed on the internal surface of second substrate 32. A transparent common electrode 311 for driving the liquid crystal in conjunction with each pixel ,.
212.~09~
~lectrode 322 is formed on the overall internal surface of first substrate 31. A plurality of black matrices 312 for defining a light transmitting regions 313 therebetween and corresponding to each pixel electrode 322 are ~rovided on common electrodes 311. A microlens sheet 34 having a plurality of microlens 341 is attached on the external surface (top surface of the first substrate 31 in Fig.2), and each microlens 341 is faced with each light transmitting region 313 in order to converge the incident light 27 onto each pixel electrode 322 of liquid crystal 33 via light transmitting region 313. In such a configuration of the liquid crystal display panel, the incident parallel source light passed through each microlens is focused on an effective pixel area via the corresponding light transmitting region 313, so as to compensate for the blockage of source light due to the --presence of black matrix 312. Especially, the aperture ratio of each pixel is substantially increased by means of the optical function of microlenses 341.
However, while the effective pixel aperture ratio of the liquid crystal display panel is increased by using the microlenses, the converging action of the microlenses deteriorates the linearity of the light. Light rays are converged by each microlens 341 onto principal focus F of the microlens 341 which point F is located in a pixel area, and then the light rays diyerge after passing through focus F.
i Such divergent light forms an image on the screen having reduced sharpness. Further, a projector using such a liquid crystal display panel must employ a large-diameter projection .
'`.': ' ': ' ~
~:, - - :
~2~098 lens system 6 (of Fig.1) for receiving the entire light beam diverged after passing through the liquid crystal.
Accordingly, such a configuration necessitates a large optical system for a liquid crystal pro~ector and increased production cost.
Summary of the Invention It is an object of the present invention to provide a liquid crystal display panel which overcomes the problem of divergence of the image light rays so as to realize a sharp image.
It is another object of the present invention to provide a liquid crystal projector in which, a liquid crystal display panel which corrects for the divergence of light is employed '!' 15 in order to reduce the necessary diameter of a projection lens j~ system.
;~ It is still another object of the present invention to provide a liquid crystal projector which is inexpensive and which realizes a sharp image.
.~
To accomplish the first object of the present invention, there is provided a liquid crystal display panel, wherein a layer of liquid crystal is disposed to fill a space between first and second substrates spaced apart from each other;
liquid crystal driving means having opposing respective electrodes are formed on the internal surfaces of the first and second substrates so as to drive the liquid crystal in units of pixels arranged in a predetermined pattern; light converging means are positioned between the first substrate ~3 4 .~ .
~ . ~ . . . . . .
' 2~098 and a light source, so as to converge light rays incident on each of the pixels; and light compensating means are formed on an external surface of the second substrate, so as to render parallel the light rays emitted from each of the pixels.
To accomplish the second and third objects of the present inventions, there is provided a liquid crystal projector comprising: a light source; a liquid crystal display panel having a liquid crystal layer, first and second substrates disposed on upper and lower sides of the liquid crystal layer, respectively, and a liquid crystal driving means for driving the liquid crystal layer; a light converging means placed on a light receiving side of the liquid crystal display panel for converging incident light rays onto the liquid crystal layer;
a light compensating means placed on a light emitting side of the liquid crystal display panel for rendering parallel light rays passing through the liquid crystal layer; and a projection lens system for projecting light rays passing through the light compensating means onto a screen.
In the liquid crystal display panel and liquid crystal projector having such a configuration, the liquid crystal driving means includes a common electrode formed on one of the first and second substrates, a pixel electrode formed on the other of the first and second substrates, and a switching device for driving the pixel electrode.
`b, 25 A black matrix for permitting light transmission only `, through a pixel area corresponding to the pixel electrode is provided on one of the first and second substrates on which the common electrode is formed.
. .
... . .
The light converging means has a converging lens array.
The light compensating means has a compensating lens array ` exhibiting a converging effect when light incident thereto is divergent with respect to the optical axis, or has a compensating lens array exhibiting a diverging effect when the light incident thereto is convergent with respect to the ; optical axis, so that light rays passing through the light compensating means are rendered parallel with the optical axis. This compensation of the output light allows the minimization of the diameter of the projection lens system, thereby realizing a good-quality image.
:
Brief Descrlption of the Drawings The above objects and advantages of the present invention will become more apparent by describing in detail a preferred embodiment thereof with reference to the attached drawings in which:
Fig.l is a schematic configuration view of a conventional liquid crystal projector;
Fig.2 is a schematic cross-sectional view of a liquid crystal display panel for the conventional liquid crystal projector of Fig.l;
Figs.3 and 4 schematically illustrate the optical ` function of a liquid crystal display panel according to the present invention;
1 25 Fig.5 is a schematic cross-sectional view of a first ¦ embodiment of the liquid crystal display panel according to the present invention as shown n Fig.3;
212~098 Fig.6 is a schematic cross-sectional view of a second embodiment of the liquid crystal display panel according to the present invention as shown in Fig.4; and Fig.7 is a sche~atic configuration view of a liquid crystal projector according to the present invention.
Detailed Description of the Invention Referring to Figs.3 and 4, a first microlens 441 (being a convex-plano lens) serving as a light converging means and a second microlens 442a (being a plano-concave lens as shown in Fig.3) or 442b (being plano-convex as shown in Fig.4) serving as a light compensating means are respectively provided on the light incoming side and light outgoing side of a unit pixel area 400 of the liquid crystal display panel located along an optical axis 401 of proceeding light rays 403. In Fig.3, a principal focus Fa of the first microlens 441 is located behind pixel 400, and second microlens 442a, which is a plano-concave lens, is located between the pixel 400 and focus Fa of the first microlens 441. In Fig.4, a principal focus Fb of first microlens 441 is located adjacent to pixel 400, and second microlens 442b, which is a plano-convex lens, is placed outside of the focal length of first microlens 441. In such configurations, the light rays convergently refracted by the ! first microlens 441 are convergently refracted by the second ~ microlens 442a which is a plano-concave lens, and are rendered ¦ 25 parallel with the optical axis 401 (as shown in Fig.3).
In another way, the light rays convergently refracted by the first microlens 441 are divergently refracted by the '~ .
.
212~098 second microlens 442b which is a p~ano-convex ]ens, and are rendered parallel with the optical axis 401 (as shown in Fig.4), so as to enhance the effective pixel aperture ratio and simul'-aneously to reduce the necessary diameter of the projection lens constituting the optical system of the liquid crystal projector.
Fig.5 illustrates a pixel area of a liquid crystal display panel based upon Fig.3. Referring to Fig.5, first and second substrates 41 and 42 are arranged to be spaced apart by a predetermined distance. Liquid crystal 43 is filled between the first and second substrates 41 and 42. A conventional driving means for driving the liquid crystal 43 is provided on ¦ the internal surfaces of first and second substrates 41 and 42. A pair of TFTs 421 serving as the switching element of the driving means are placed on the internal surface of the second substrate 42 with a predetermined distance from each other, and a pixel electrode 402 for driving the liquid crystal is located between TFTs 421. Transparent common electrode 411 is 3 formed on the overall internal surface of first substrate 41 for driving the liquid crystal 43 in conjunction with pixel electrode 402. A pair of black matrices 412 for defining a light-transmitting region 413 corresponding to each pixel electrode 402 is provided on common electrode 411. A first microlens 441 (a convex-plano lens) corresponding to each light-transmitting region 413 for convergently refracting incident light rays 403 onto the pixel area of liquid crystal 43 via light-transmitting region 413 is attached on the external surface of the first substrate 41. A corresponding ' . :
212~098 ~lano-concave second microlens 442a (a plano-convex lens) for divergently refracting output light rays 404 and rendering them parallel with the optical axis is provided on the external surface (at the bottom in the drawing) of second substrate 42.
Here, second microlens 442a is located between first microlens 441 and principal focus Fa of first microlens 441.
First and second microlenses 441 and 442a may be attached directly on the respective external surfaces of first and second substrates 41 and 42, or may be spaced apart from the first and second substrates 41 and 42 by a predetermined distance.
In the liquid crystal display panel of the present invention, incident parallel light rays 403 are convergently refracted while passing through first microlens 441, and then ,j are made incident on pixel 400. Output light rays 404 passing '.i `i through pixel 400 are divergently refracted by second microlens 442a and rendered parallel to the optical axis. Such ~ a compensation of the output light rays realizes a fine image.
f~ 20 Since first microlens 441 converges all of the incident light ~ rays and focuses the converged light rays on the pixel, most i~ of the light is made to be incident on the pixel 400, not reaching the black matrix 412. This prevents light blockage by . the black matrix 412 and therefore enhances the pixel :~, 25 luminance. The incident light rays converged by the first ~` microlens 441 and passing through the pixel 400 are refracted ,~ and diverged while passing through the second microlens 442a to become parallel with the optical axis. Here, the second . , ,, .
, 212~098 microlens 442a functions to render parallel the incident light rays converged by the first microlens 441. With the second microlens 442a, the linearity of the output light rays is enhanced to thereby realize a sharp image.
Fig.6 illustrates another embodiment of the liquid crystal display panel of the present invention. In this liquid crystal display panel, a second microlens 442b is a plano-$ convex lens so as to refractively converge the light rays passing out of the pixel area 400. Since second microlens 442b is located outside of the focal length of first microlens 441, second microlens 442b reconverges the light rays converged by first microlens 441 and then diverged after passing through focus Fb, so as to render parallel the diverged light rays.
The second embodiment yields the same effect as that of the first embodiment by outputting the light rays in parallel.
;~ As another method for realizing such light ray convergence and parallel light rays, a light converging means may be constructed to converge incident light rays by stacking material in which the index of refraction is gradually lowered from the center to the periphery, on portions of the first ~ substrate corresponding to light transmitting regions 413. In `' portions of the second substrate corresponding to the light emitting regions, a light compensating means serving as the second microlens may be provided to have a converging or diverging effect by stacking material in which the index of refraction is gradually lowered or increased from the center to the periphery.
Further, as another embodiment, the portions \
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212~098 corresponding to the light transmitting regions and light emitting regions of the first and second substrates may be processed in a predetermined pattern so as to obtain a microlens array having a desired form.
Fig.7 shows a schematic configuration of a liquid crystal projector of the present invention.
Referring to Fig.7, the liquid crystal projector of the present invention having a similar structure to the conventional one, includes a parabolic reflection mirror 120 for reflecting light emitted from a light source 100, a liquid ' crystal display panel 40 disposed along the proceeding path of the light reflected by the reflection mirror, and driven by a driving circuit 78, polarizing plates 140 and 150 located in ~ front of and behind liquid crystal display panel 40 for r 15 controlling the polarization of light, and a projection lens system 160 disposed along the proceeding path of the light having passed through liquid crystal 40 for projecting an enlarged projection image onto a screen 170.
As a feature of the present invention, first and second microlens sheets 440 and 442 are provided, each having respective microlenses 441 or 442a (or 442b) which correspond to one another. The first microlens sheet 440 is a light converging means which converges, in units of pixels, incident light rays 79 emitted from light source 100, reflected by the reflection mirror 120 and having only a specific polarized component filtered by polarizing plate 140, and then passes the converged light rays to liquid crystal display panel 40.
The second microlens sheet 442 is a light compensating means 11 ' .
: : : .
212~098 which compensates for the light passing through liquid crystal display panel 40 in units of pixels so as to form parallel output light rays 80.
Liquid crystal display panel 40 operates in accordance ; 5 with an image signal from driving circuit 78 so as to transmit or block incident light 79 in units of pixels. Microlenses 441, 442a and 442b of the first and second microlens sheets 440 and 442 are the same as those of the liquid crystal display panel of the present invention. If the output light :~ 10 rays passing through the liquid crystal are in a state of divergence, the second microlens 442a compensates for the .. diverged output light rays by its converging effect so as to render parallel the output light rays 80. If the output light ~,. rays passing through the liquid crystal display panel are in a state of convergence, the second microlens 442b compensates ~ for the converged output light rays by its diverging effect so ` as to render parallel the output light rays 80. The output light rays compensated as above while passing through the second microlens sheet 442 reach screen 170 via projection lens system 160 and therefore form an enlarged image on the screen 170.
In the liquid crystal projector, since the light to be passed through the liquid crystal display panel is converged : by the first microlens sheet serving as the light converging 25 means and having the first microlens array, the effective pixel aperture ratio of the liquid crystal display panel is enhanced. Further, since the light rays converged by the light converging means are converted into parallel light rays by the :. . :: :
, : : ~ ~ : : , :
~250g8 second microlens sheet serving as the light compensating means and having the second microlens array, the divergence angle of the light rays passing through the projection lens system is greatly reduced compared with that of the conventional liquid crystal projector. Accordingly, an image obtained on the screen by projecting the output light rays passing through the projection lens system at a reduced divergence angle becomes more clear than that from the conventional projector. In addition, since the diameter of the projection lens system can be reduced compared with that of the conventional one, it is feasible to miniaturize the projection lens system and to thereby decrease the production cost of the whole projector.
.: : ~ ' '.' ' , :
- .
In order to obtain a bright image in such a liquid crystal projector, it is required to maximize an effective pixel aperture ratio of the liquid crystal display panel 3. A
i 15 conventional general liquid crystal display panel makes use of a thin film transistor (TFT) as its pixel switching element.
Referring to Fig.2, first and second substrates 31 and 32 are arranged to be spaced apart by a predetermined distance.
Liquid crystal 33 fills the space between the first and second substrates 31 and 32. A driving means for driving each pixel of the liquid crystal display panel 3 is provided on the respective internal surfaces of first and second substrates 31 and 32. A plurality of pixel electrodes 322 for driving liquid crystal 33 in a predetermined pixel pattern and TFTs 321 serving as the switching element of the driving means of the corresponding pixel are placed on the internal surface of second substrate 32. A transparent common electrode 311 for driving the liquid crystal in conjunction with each pixel ,.
212.~09~
~lectrode 322 is formed on the overall internal surface of first substrate 31. A plurality of black matrices 312 for defining a light transmitting regions 313 therebetween and corresponding to each pixel electrode 322 are ~rovided on common electrodes 311. A microlens sheet 34 having a plurality of microlens 341 is attached on the external surface (top surface of the first substrate 31 in Fig.2), and each microlens 341 is faced with each light transmitting region 313 in order to converge the incident light 27 onto each pixel electrode 322 of liquid crystal 33 via light transmitting region 313. In such a configuration of the liquid crystal display panel, the incident parallel source light passed through each microlens is focused on an effective pixel area via the corresponding light transmitting region 313, so as to compensate for the blockage of source light due to the --presence of black matrix 312. Especially, the aperture ratio of each pixel is substantially increased by means of the optical function of microlenses 341.
However, while the effective pixel aperture ratio of the liquid crystal display panel is increased by using the microlenses, the converging action of the microlenses deteriorates the linearity of the light. Light rays are converged by each microlens 341 onto principal focus F of the microlens 341 which point F is located in a pixel area, and then the light rays diyerge after passing through focus F.
i Such divergent light forms an image on the screen having reduced sharpness. Further, a projector using such a liquid crystal display panel must employ a large-diameter projection .
'`.': ' ': ' ~
~:, - - :
~2~098 lens system 6 (of Fig.1) for receiving the entire light beam diverged after passing through the liquid crystal.
Accordingly, such a configuration necessitates a large optical system for a liquid crystal pro~ector and increased production cost.
Summary of the Invention It is an object of the present invention to provide a liquid crystal display panel which overcomes the problem of divergence of the image light rays so as to realize a sharp image.
It is another object of the present invention to provide a liquid crystal projector in which, a liquid crystal display panel which corrects for the divergence of light is employed '!' 15 in order to reduce the necessary diameter of a projection lens j~ system.
;~ It is still another object of the present invention to provide a liquid crystal projector which is inexpensive and which realizes a sharp image.
.~
To accomplish the first object of the present invention, there is provided a liquid crystal display panel, wherein a layer of liquid crystal is disposed to fill a space between first and second substrates spaced apart from each other;
liquid crystal driving means having opposing respective electrodes are formed on the internal surfaces of the first and second substrates so as to drive the liquid crystal in units of pixels arranged in a predetermined pattern; light converging means are positioned between the first substrate ~3 4 .~ .
~ . ~ . . . . . .
' 2~098 and a light source, so as to converge light rays incident on each of the pixels; and light compensating means are formed on an external surface of the second substrate, so as to render parallel the light rays emitted from each of the pixels.
To accomplish the second and third objects of the present inventions, there is provided a liquid crystal projector comprising: a light source; a liquid crystal display panel having a liquid crystal layer, first and second substrates disposed on upper and lower sides of the liquid crystal layer, respectively, and a liquid crystal driving means for driving the liquid crystal layer; a light converging means placed on a light receiving side of the liquid crystal display panel for converging incident light rays onto the liquid crystal layer;
a light compensating means placed on a light emitting side of the liquid crystal display panel for rendering parallel light rays passing through the liquid crystal layer; and a projection lens system for projecting light rays passing through the light compensating means onto a screen.
In the liquid crystal display panel and liquid crystal projector having such a configuration, the liquid crystal driving means includes a common electrode formed on one of the first and second substrates, a pixel electrode formed on the other of the first and second substrates, and a switching device for driving the pixel electrode.
`b, 25 A black matrix for permitting light transmission only `, through a pixel area corresponding to the pixel electrode is provided on one of the first and second substrates on which the common electrode is formed.
. .
... . .
The light converging means has a converging lens array.
The light compensating means has a compensating lens array ` exhibiting a converging effect when light incident thereto is divergent with respect to the optical axis, or has a compensating lens array exhibiting a diverging effect when the light incident thereto is convergent with respect to the ; optical axis, so that light rays passing through the light compensating means are rendered parallel with the optical axis. This compensation of the output light allows the minimization of the diameter of the projection lens system, thereby realizing a good-quality image.
:
Brief Descrlption of the Drawings The above objects and advantages of the present invention will become more apparent by describing in detail a preferred embodiment thereof with reference to the attached drawings in which:
Fig.l is a schematic configuration view of a conventional liquid crystal projector;
Fig.2 is a schematic cross-sectional view of a liquid crystal display panel for the conventional liquid crystal projector of Fig.l;
Figs.3 and 4 schematically illustrate the optical ` function of a liquid crystal display panel according to the present invention;
1 25 Fig.5 is a schematic cross-sectional view of a first ¦ embodiment of the liquid crystal display panel according to the present invention as shown n Fig.3;
212~098 Fig.6 is a schematic cross-sectional view of a second embodiment of the liquid crystal display panel according to the present invention as shown in Fig.4; and Fig.7 is a sche~atic configuration view of a liquid crystal projector according to the present invention.
Detailed Description of the Invention Referring to Figs.3 and 4, a first microlens 441 (being a convex-plano lens) serving as a light converging means and a second microlens 442a (being a plano-concave lens as shown in Fig.3) or 442b (being plano-convex as shown in Fig.4) serving as a light compensating means are respectively provided on the light incoming side and light outgoing side of a unit pixel area 400 of the liquid crystal display panel located along an optical axis 401 of proceeding light rays 403. In Fig.3, a principal focus Fa of the first microlens 441 is located behind pixel 400, and second microlens 442a, which is a plano-concave lens, is located between the pixel 400 and focus Fa of the first microlens 441. In Fig.4, a principal focus Fb of first microlens 441 is located adjacent to pixel 400, and second microlens 442b, which is a plano-convex lens, is placed outside of the focal length of first microlens 441. In such configurations, the light rays convergently refracted by the ! first microlens 441 are convergently refracted by the second ~ microlens 442a which is a plano-concave lens, and are rendered ¦ 25 parallel with the optical axis 401 (as shown in Fig.3).
In another way, the light rays convergently refracted by the first microlens 441 are divergently refracted by the '~ .
.
212~098 second microlens 442b which is a p~ano-convex ]ens, and are rendered parallel with the optical axis 401 (as shown in Fig.4), so as to enhance the effective pixel aperture ratio and simul'-aneously to reduce the necessary diameter of the projection lens constituting the optical system of the liquid crystal projector.
Fig.5 illustrates a pixel area of a liquid crystal display panel based upon Fig.3. Referring to Fig.5, first and second substrates 41 and 42 are arranged to be spaced apart by a predetermined distance. Liquid crystal 43 is filled between the first and second substrates 41 and 42. A conventional driving means for driving the liquid crystal 43 is provided on ¦ the internal surfaces of first and second substrates 41 and 42. A pair of TFTs 421 serving as the switching element of the driving means are placed on the internal surface of the second substrate 42 with a predetermined distance from each other, and a pixel electrode 402 for driving the liquid crystal is located between TFTs 421. Transparent common electrode 411 is 3 formed on the overall internal surface of first substrate 41 for driving the liquid crystal 43 in conjunction with pixel electrode 402. A pair of black matrices 412 for defining a light-transmitting region 413 corresponding to each pixel electrode 402 is provided on common electrode 411. A first microlens 441 (a convex-plano lens) corresponding to each light-transmitting region 413 for convergently refracting incident light rays 403 onto the pixel area of liquid crystal 43 via light-transmitting region 413 is attached on the external surface of the first substrate 41. A corresponding ' . :
212~098 ~lano-concave second microlens 442a (a plano-convex lens) for divergently refracting output light rays 404 and rendering them parallel with the optical axis is provided on the external surface (at the bottom in the drawing) of second substrate 42.
Here, second microlens 442a is located between first microlens 441 and principal focus Fa of first microlens 441.
First and second microlenses 441 and 442a may be attached directly on the respective external surfaces of first and second substrates 41 and 42, or may be spaced apart from the first and second substrates 41 and 42 by a predetermined distance.
In the liquid crystal display panel of the present invention, incident parallel light rays 403 are convergently refracted while passing through first microlens 441, and then ,j are made incident on pixel 400. Output light rays 404 passing '.i `i through pixel 400 are divergently refracted by second microlens 442a and rendered parallel to the optical axis. Such ~ a compensation of the output light rays realizes a fine image.
f~ 20 Since first microlens 441 converges all of the incident light ~ rays and focuses the converged light rays on the pixel, most i~ of the light is made to be incident on the pixel 400, not reaching the black matrix 412. This prevents light blockage by . the black matrix 412 and therefore enhances the pixel :~, 25 luminance. The incident light rays converged by the first ~` microlens 441 and passing through the pixel 400 are refracted ,~ and diverged while passing through the second microlens 442a to become parallel with the optical axis. Here, the second . , ,, .
, 212~098 microlens 442a functions to render parallel the incident light rays converged by the first microlens 441. With the second microlens 442a, the linearity of the output light rays is enhanced to thereby realize a sharp image.
Fig.6 illustrates another embodiment of the liquid crystal display panel of the present invention. In this liquid crystal display panel, a second microlens 442b is a plano-$ convex lens so as to refractively converge the light rays passing out of the pixel area 400. Since second microlens 442b is located outside of the focal length of first microlens 441, second microlens 442b reconverges the light rays converged by first microlens 441 and then diverged after passing through focus Fb, so as to render parallel the diverged light rays.
The second embodiment yields the same effect as that of the first embodiment by outputting the light rays in parallel.
;~ As another method for realizing such light ray convergence and parallel light rays, a light converging means may be constructed to converge incident light rays by stacking material in which the index of refraction is gradually lowered from the center to the periphery, on portions of the first ~ substrate corresponding to light transmitting regions 413. In `' portions of the second substrate corresponding to the light emitting regions, a light compensating means serving as the second microlens may be provided to have a converging or diverging effect by stacking material in which the index of refraction is gradually lowered or increased from the center to the periphery.
Further, as another embodiment, the portions \
. ~
. :: : . , :
212~098 corresponding to the light transmitting regions and light emitting regions of the first and second substrates may be processed in a predetermined pattern so as to obtain a microlens array having a desired form.
Fig.7 shows a schematic configuration of a liquid crystal projector of the present invention.
Referring to Fig.7, the liquid crystal projector of the present invention having a similar structure to the conventional one, includes a parabolic reflection mirror 120 for reflecting light emitted from a light source 100, a liquid ' crystal display panel 40 disposed along the proceeding path of the light reflected by the reflection mirror, and driven by a driving circuit 78, polarizing plates 140 and 150 located in ~ front of and behind liquid crystal display panel 40 for r 15 controlling the polarization of light, and a projection lens system 160 disposed along the proceeding path of the light having passed through liquid crystal 40 for projecting an enlarged projection image onto a screen 170.
As a feature of the present invention, first and second microlens sheets 440 and 442 are provided, each having respective microlenses 441 or 442a (or 442b) which correspond to one another. The first microlens sheet 440 is a light converging means which converges, in units of pixels, incident light rays 79 emitted from light source 100, reflected by the reflection mirror 120 and having only a specific polarized component filtered by polarizing plate 140, and then passes the converged light rays to liquid crystal display panel 40.
The second microlens sheet 442 is a light compensating means 11 ' .
: : : .
212~098 which compensates for the light passing through liquid crystal display panel 40 in units of pixels so as to form parallel output light rays 80.
Liquid crystal display panel 40 operates in accordance ; 5 with an image signal from driving circuit 78 so as to transmit or block incident light 79 in units of pixels. Microlenses 441, 442a and 442b of the first and second microlens sheets 440 and 442 are the same as those of the liquid crystal display panel of the present invention. If the output light :~ 10 rays passing through the liquid crystal are in a state of divergence, the second microlens 442a compensates for the .. diverged output light rays by its converging effect so as to render parallel the output light rays 80. If the output light ~,. rays passing through the liquid crystal display panel are in a state of convergence, the second microlens 442b compensates ~ for the converged output light rays by its diverging effect so ` as to render parallel the output light rays 80. The output light rays compensated as above while passing through the second microlens sheet 442 reach screen 170 via projection lens system 160 and therefore form an enlarged image on the screen 170.
In the liquid crystal projector, since the light to be passed through the liquid crystal display panel is converged : by the first microlens sheet serving as the light converging 25 means and having the first microlens array, the effective pixel aperture ratio of the liquid crystal display panel is enhanced. Further, since the light rays converged by the light converging means are converted into parallel light rays by the :. . :: :
, : : ~ ~ : : , :
~250g8 second microlens sheet serving as the light compensating means and having the second microlens array, the divergence angle of the light rays passing through the projection lens system is greatly reduced compared with that of the conventional liquid crystal projector. Accordingly, an image obtained on the screen by projecting the output light rays passing through the projection lens system at a reduced divergence angle becomes more clear than that from the conventional projector. In addition, since the diameter of the projection lens system can be reduced compared with that of the conventional one, it is feasible to miniaturize the projection lens system and to thereby decrease the production cost of the whole projector.
.: : ~ ' '.' ' , :
- .
Claims (17)
1. A liquid crystal display panel comprising:
first and second substrates spaced apart from each other with liquid crystal filled therebetween;
liquid crystal driving means having opposing electrodes which is formed on the respective internal surfaces of said first and second substrates so as to drive said liquid crystal in units of pixels arranged in a predetermined pattern;
light converging means positioned between said first substrate and a light source so as to converge light rays incident on each of said pixels; and light compensating means formed on an external surface of said second substrate, so as to render parallel the light rays emitted from each of said pixels.
first and second substrates spaced apart from each other with liquid crystal filled therebetween;
liquid crystal driving means having opposing electrodes which is formed on the respective internal surfaces of said first and second substrates so as to drive said liquid crystal in units of pixels arranged in a predetermined pattern;
light converging means positioned between said first substrate and a light source so as to converge light rays incident on each of said pixels; and light compensating means formed on an external surface of said second substrate, so as to render parallel the light rays emitted from each of said pixels.
2. A liquid crystal display panel as claimed in claim 1, wherein said light converging means has an array composed of a plurality of first lenses each having a light-converging effect, and said light compensating means has an array composed of a plurality of second lenses, corresponding to said first lenses and each having a light-converging or diverging effect, respectively.
3. A liquid crystal display panel as claimed in claim 2, wherein each of said second lenses is convex-plano lens having a light-converging effect and located on the external surface of said first substrate.
4. A liquid crystal display panel as claimed in claim 2, wherein each of said second lenses is plano-convex lens having a light-converging effect with respect to light passing through said corresponding first lens and pixel unit and is located on the external surface of said second substrate.
5. A liquid crystal display panel as claimed in claim 4, wherein each of said second lenses is located within a focal length of said corresponding first lens.
6. A liquid crystal display panel as claimed in claim 2, wherein each of said second lenses is plano-concave lens having a light-diverging effect with respect to light passing through said corresponding first lens and pixel unit and is located on the external surface of said second substrate.
7. A liquid crystal display panel as claimed in claim 6, wherein each of said second lenses is located outside of a focal length of said corresponding first lens.
8. A liquid crystal display panel as claimed in claim 2, wherein said first and second lenses are integrally formed with said corresponding first and second substrates, respectively.
9. A liquid crystal projector comprising:
a light source;
a liquid crystal display panel having a liquid crystal layer, first and second substrates disposed on upper and lower sides of the liquid crystal layer, respectively, and a liquid crystal driving means for driving the liquid crystal layer in units' of pixels;
a light converging means placed on a light receiving side of said liquid crystal display panel for converging incident light rays onto said liquid crystal layer;
a light compensating means placed on a light emitting side of said liquid crystal display panel for rendering parallel the light rays passing through said liquid crystal layer; and a projection lens system for projecting the light rays passing through said light compensating means onto a screen.
a light source;
a liquid crystal display panel having a liquid crystal layer, first and second substrates disposed on upper and lower sides of the liquid crystal layer, respectively, and a liquid crystal driving means for driving the liquid crystal layer in units' of pixels;
a light converging means placed on a light receiving side of said liquid crystal display panel for converging incident light rays onto said liquid crystal layer;
a light compensating means placed on a light emitting side of said liquid crystal display panel for rendering parallel the light rays passing through said liquid crystal layer; and a projection lens system for projecting the light rays passing through said light compensating means onto a screen.
10. A liquid crystal projector as claimed in claim 9, wherein said light converging means has an array composed of a plurality of first lenses, and said light compensating means has a array composed of a plurality of second lenses corresponding to said first lenses, respectively.
11. A liquid crystal display panel projector as claimed in claim 10, wherein each of said first lenses is convex-plano lens having a light-converging effect and is located on the external surface of said first substrate.
12. A liquid crystal display panel projector as claimed in claim 10, wherein each of said second lenses is plano-convex lens having a light-converging effect with respect to light passing through said corresponding first lens and pixel unit and is located on the external surface of said second substrate.
13. A liquid crystal display panel projector as claimed in claim 12, wherein each of said second lenses is located within a focal length of said corresponding first lens.
14. A liquid crystal display panel projector as claimed in claim 10, wherein each of said second lenses is plano-concave lens having a light-diverging effect with respect to light passing through said corresponding first lens and pixel unit and is located on the external surface of said second substrate.
15. A liquid crystal display panel projector as claimed in claim 14, wherein each of said second lenses is located outside of a focal length of said corresponding first lens.
16. A liquid crystal display panel projector as claimed in claim 10, wherein said first and second lenses are integrally formed with said corresponding first and second substrates, respectively.
17
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR93-11025 | 1993-06-16 | ||
| KR1019930011025A KR970000348B1 (en) | 1993-06-16 | 1993-06-16 | Liquid crystal panel for liquid crystal projector |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2125098A1 true CA2125098A1 (en) | 1994-12-17 |
Family
ID=19357533
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002125098A Abandoned CA2125098A1 (en) | 1993-06-16 | 1994-06-03 | Liquid crystal display panel and liquid crystal projector employing the same |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPH0713161A (en) |
| KR (1) | KR970000348B1 (en) |
| CN (1) | CN1102002A (en) |
| CA (1) | CA2125098A1 (en) |
| DE (1) | DE4420828A1 (en) |
| FR (1) | FR2706666A1 (en) |
| GB (1) | GB2279171A (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3278084B2 (en) * | 1993-04-30 | 2002-04-30 | キヤノン株式会社 | Display device and projection device using the same |
| KR100213968B1 (en) | 1996-07-15 | 1999-08-02 | 구자홍 | Liquid crystal display device |
| JP3515880B2 (en) * | 1997-06-30 | 2004-04-05 | ダイワ精工株式会社 | Fishing reel |
| US6643067B2 (en) * | 2000-11-22 | 2003-11-04 | Seiko Epson Corporation | Electro-optical device and electronic apparatus |
| US8059345B2 (en) * | 2002-07-29 | 2011-11-15 | Digitaloptics Corporation East | Integrated micro-optical systems |
| JP6123317B2 (en) | 2013-02-05 | 2017-05-10 | セイコーエプソン株式会社 | Liquid crystal device and electronic device |
| FR3054021A1 (en) * | 2016-07-13 | 2018-01-19 | Valeo Vision | LIGHT DEVICE FOR VARIABLE IMAGE PROJECTION |
| CN112863326B (en) * | 2019-11-12 | 2022-12-09 | Oppo广东移动通信有限公司 | Transparent screen, manufacturing method of transparent screen and mobile terminal |
| CN111312739B (en) * | 2020-02-26 | 2022-10-21 | 云谷（固安）科技有限公司 | Display panel and display device |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0642126B2 (en) * | 1988-10-26 | 1994-06-01 | シャープ株式会社 | Projection type image display device |
| JPH03140920A (en) * | 1989-10-26 | 1991-06-14 | Matsushita Electric Ind Co Ltd | Projection type display device and liquid crystal display device used for this projection type display device |
| JPH0626131A (en) * | 1992-04-16 | 1994-02-01 | Takenaka Komuten Co Ltd | Execution method of precast concrete block with sound absorbing material |
-
1993
- 1993-06-16 KR KR1019930011025A patent/KR970000348B1/en not_active IP Right Cessation
-
1994
- 1994-06-03 CA CA002125098A patent/CA2125098A1/en not_active Abandoned
- 1994-06-07 JP JP6150300A patent/JPH0713161A/en active Pending
- 1994-06-10 GB GB9411657A patent/GB2279171A/en not_active Withdrawn
- 1994-06-14 FR FR9407234A patent/FR2706666A1/en not_active Withdrawn
- 1994-06-15 DE DE4420828A patent/DE4420828A1/en not_active Withdrawn
- 1994-06-16 CN CN94106478A patent/CN1102002A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| GB9411657D0 (en) | 1994-08-03 |
| FR2706666A1 (en) | 1994-12-23 |
| CN1102002A (en) | 1995-04-26 |
| JPH0713161A (en) | 1995-01-17 |
| GB2279171A (en) | 1994-12-21 |
| DE4420828A1 (en) | 1994-12-22 |
| KR970000348B1 (en) | 1997-01-08 |
| KR950001341A (en) | 1995-01-03 |
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