JP2003015123A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-quality image which is highly accurately adjusted in a liquid crystal display device. SOLUTION: A reflection type liquid crystal display device has a transmission type liquid crystal display panel 1 and a DMD(digital micro-mirror device) element 2 disposed at the back surface side of the transmission type liquid crystal display panel. Illumination light is made incident on the micro-mirror planes 4 and 4b of the DMD element, reflected further vertically (incident light 8, 8a and 8b, reflected light 9 and 9b), and the transmission type liquid crystal display panel 1 is irradiated with the illumination light. Micro-mirrors 4, 4a and 4b are provided one to one corresponding to each LCD pixel of the transmission type liquid crystal display panel. The illumination light is transmitted through the LCD pixels, is made incident or reflected vertically to the micro- mirrors, and is transmitted through the LCD pixels again.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device for improving luminance unevenness, flicker, crosstalk and the like which occur in the display device.

[0002]

2. Description of the Related Art As a liquid crystal display device used in an image forming section of a recent liquid crystal projector, a reflection type liquid crystal display device having a higher display efficiency than a transmission type liquid crystal display device has been attracting attention. The basic structure of a typical reflective display device is shown in FIGS.
Shown in. First, the schematic reflection type liquid crystal display device shown in FIG. 4 will be briefly described below.

As shown in FIG. 4, glass substrates 101, 1
02 and a liquid crystal layer 103 sandwiched between these glass substrates, and a TFT (Thin Film Transistor) and an LCD (Liquid Cr
ystal Display) An electrode array of pixels is formed.

The reflective pixel electrode 104 in this case is usually an aluminum film formed by vapor deposition. Then, in such a basic structure, the illumination light enters from the upper surface of the reflective liquid crystal display panel 105, and is reflected by the reflective pixel electrode 104 to be displayed as an image.

As a reflection type display device, a DMD (Digital Micro-mirror Device) 10 as shown in FIG. 5 is used.
There is 6. Next, the mechanism of the DMD 106 will be described. In the DMD 106, as shown in FIG.
Micro mirrors 108, 108a, 108b and the like are formed on the substrate 7. Then, each of these micromirror surfaces changes up to the angle of contact with the stopper 110 by the hinge 109.

Then, the incident light 11 which is the above-mentioned irradiation light
DMD 106 having the above-described structure
Incident at an angle. The incident light 11 from this diagonal
1, 111a and 111b are micromirrors 1, respectively.
08, 108a, 108b are reflected by the surface and reflected light 112,
112a and 112b. In this way, the video pixels 113, 113a, 113b are formed. In the case of this conventional technique, the DMD 106 moves ± 10 ° about the hinge 109 until it is restricted by the stopper 110, for example, as shown in FIG.
It is an adjustment system that creates an ON state by incidence or vertical emission or an OFF state by 40 ° emission and controls the brightness level by pulse width modulation.

[0007]

In a projector adjustment system using a liquid crystal display device, automatic adjustment at a production site is one of the important factors. Therefore,
For correction of uneven brightness, a raster screen is displayed, and as will be described later, the image projected on the screen by the CCD camera is captured, and the brightness of a certain area, usually the center, is used as the reference, and the in-plane brightness is used as the reference. If the flicker is adjusted, an adjustment pattern, usually every other horizontal line with intermediate brightness, is displayed so that the change in light intensity from the projection lens captured by the photodetector is minimized. Works, and the technique is adopted.

However, when the above-mentioned conventional reflection type display device is used, it is possible to construct an automatic adjustment system, but regarding correction of luminance unevenness, the in-plane is divided into several numbers in the vertical and horizontal directions. Since it is a correction for each minute area, the correction within the area is impossible, and the brightness level that can be corrected depends on the hardware configuration and is usually several levels. To be realized. Further, the flicker adjustment is limited to the adjustment to the minimum value, and the crosstalk adjustment is usually not adjusted. For this reason,
It cannot be said to be sufficient for highly accurate luminance unevenness correction, flicker, and crosstalk adjustment.

One of the main objects of the present invention is to provide a high-quality image adjusted with high precision in a liquid crystal display device. Another main object of the present invention is to provide a highly accurate automated adjustment system in a liquid crystal display device.

[0010]

To this end, the liquid crystal display device according to the present invention includes a transmissive liquid crystal display panel and a DMD (Digital
Micro-mirror device), and the brightness of the transmitted light from the transmissive liquid crystal display panel is adjusted by the DMD device.

Alternatively, the liquid crystal display device of the present invention has a transmissive liquid crystal display panel and a DMD element arranged on the back side of the transmissive liquid crystal display panel, and the illumination light is the DM light.
The transmissive liquid crystal display panel is irradiated with light that is vertically incident on the micro mirror surface of the D element and further vertically reflected. Here, the illumination light is transmitted through the LCD pixels, vertically reflected and reflected by the micromirrors, and is again reflected by the L
It will pass through the CD pixels. Further, a partition for absorbing light is provided around each micro mirror of the DMD element.

Each L of the transmissive liquid crystal display panel
DMD for CD (Liquid Crystal Display) pixels
The element micromirrors are provided in a one-to-one correspondence.

In the present invention, the angle of the micromirror surface with respect to the optical axis of the irradiation light is changed to adjust the brightness unevenness of the transmitted light of a predetermined LCD pixel. Further, the brightness level of the transmitted light of the LCD pixels is corrected in pixel units, and flicker adjustment, crosstalk adjustment, or ghost adjustment is performed.

Further, according to the present invention, the display pattern is recognized by the signal processing unit from the input video signal of the image, the correction pattern and the correction amount are calculated by the correction processing unit, the DMD element is driven, and the flicker adjustment, It is designed to perform crosstalk adjustment or ghost adjustment.

As described above, according to the present invention, highly accurate luminance unevenness correction and flicker and crosstalk adjustment can be easily performed. Further, the present invention provides a high-quality image adjusted with high accuracy in a liquid crystal display device, and further, can provide a highly accurate automated adjustment system in a liquid crystal display device.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Next, a first embodiment of the present invention will be described with reference to FIGS. Here, FIG.
Shows the basic structure of the liquid crystal display device of the present invention. 2 shows the basic configuration of the liquid crystal projector of the present invention.

As shown in FIG. 1, a DMD element 2 is arranged on the rear surface of the transmissive liquid crystal display panel 1. This DM
The basic structure of the D element 2 is almost the same as that described in FIG. That is, on the substrate 3, the micro mirrors 4, 4a,
4b are formed respectively. Then, these micromirror surfaces are adapted to change in angles of 0 ° and 20 ° in contact with the stopper 6 by the respective hinges 5. Here, a micro mirror is provided for each LCD pixel of the transmissive liquid crystal display panel 1 in a one-to-one manner so that light transmitted through the liquid crystal is selectively reflected for each pixel to control the brightness level. It has become. The DMD element used here creates an ON state by 0 ° incidence, vertical emission, or an OFF state by 40 ° emission, and controls the brightness level by pulse width modulation. Further, each micro mirror 4, 4 a, 4 b is surrounded by a partition 7.

As shown in FIG. 1, when the light transmitted through the transmissive liquid crystal display panel 1 is in the ON state, the incident light 8 and 8b and the reflected light 9 and 9b are vertically incident by the micro mirrors, and the transmitted LCD pixel is re-illuminated. On the other hand, in the OFF state, the incident light 8a is diffusely reflected and becomes reflected light 9a.
Is absorbed by the light. Then, the brightness level is adjusted by the pulse width modulation described above. In this way, the video pixels 10, 10a, 10b with adjusted brightness levels are formed.

Next, FIG. 2 shows the structure of a liquid crystal projector using the above basic structure of the present invention. The image forming unit 1
1 uses a reflective liquid crystal display device in which a DMD element is used instead of the pixel electrode mirror.

The image forming system has the same structure as in the case of using a normal liquid crystal display panel. Input video signal 12
Is VT (applied voltage-transmittance) correction in the signal processing unit 13,
After undergoing signal processing such as γ correction, phase expansion processing is performed by the LCD drive unit 14 and then input to the LCD 15. The projection optical system has the same structure as that of the case where a normal reflection type liquid crystal display panel is used.

The light (P-polarized light and S-polarized light) output from the lamp 16 is input / output separated (P-polarized light component is transmitted, S-polarized light component is reflected), and is a PBS (polarizing beam splitter).
After passing through 17, only S-polarized component is incident on the LCD 15, DM
After being reflected at D18 and passing through LCD15 again, P
Only the polarization-modulated component passes through the PBS 17, and the projection lens 19 forms an image on the screen 20.

On the other hand, in the case of correcting the uneven brightness, the reflected light from the screen 20 is taken in by the CCD camera 21, the correction amount is determined by the correction processing section 22, and the DMD 18 selectively selects it by the DMD 18. Manipulate reflectance. The correction data is stored in the memory 24. This operation controls the brightness level.

In the case of flicker adjustment, the amplitude of a signal (usually a sine wave) taken in by the photodetector 25 provided in front of the screen 20 when displaying every other horizontal line of intermediate brightness is set. The potential of the common electrode to the liquid crystal display device is manipulated so as to minimize it, and the levels of the inversion side image amplitude and the non-inversion side image amplitude in the inversion drive are adjusted, but some remain due to insufficient storage capacity of liquid crystal pixels. Therefore, a reverse correction amount is set, and the intensity of light transmitted through the LCD 15 is controlled by the DMD 18 on a pixel-by-pixel basis to correct the projected brightness level.

Similarly, for the crosstalk adjustment, which is caused by the leak current of the TFT for each pixel, an opposite correction amount is set, and the DMD 18 controls the light intensity transmitted through the LCD 15 for each pixel, and the projected brightness level. To correct. However, flicker and crosstalk are generated depending on the pattern of the input video signal 12, unlike the occurrence of uneven brightness, so that the signal processing unit 13 recognizes the display pattern, for example, if flicker occurs within the plane. Area to be corrected by detecting in which area a pattern represented by every other horizontal line of intermediate brightness exists, and in the area of the surface where crosstalk is likely to occur , A correction amount is calculated and passed to the correction processing unit 22.

As shown in the basic structure part of the liquid crystal display device of FIG. 1, the mirror structure in which the reflection part of the image forming part is the pixel electrode of the array in the conventional reflection type liquid crystal display device shown in FIG. According to the invention, the DMD element 2 is provided on the back surface of the transmissive liquid crystal display panel 1 instead of the reflective liquid crystal display panel instead of the pixel electrode mirror in the display device. The DMD element 2 replaced with this pixel electrode mirror plays a role of correcting variations in the transmission level of liquid crystal and mutual interference between pixels in units of in-plane pixels. In this way, the uneven brightness, flicker, and
The effect of improving crosstalk can be obtained.

Next, a second embodiment of the present invention will be described. In the first embodiment, the present invention is applied to the luminance unevenness correction, the flicker adjustment, and the crosstalk adjustment, but it is also applicable to the ghost adjustment and the vertical line adjustment. It should be noted that the ghost is caused by the timing or waveform rounding of the video signal written in the liquid crystal display panel and is displayed faintly at intermediate brightness before or after a few dots of the original video. It shows that most can be removed by adjustment and waveform shaping,
If the image signal is affected by noise or the like, it cannot be removed by the above adjustment.

Therefore, for the ghost adjustment and the vertical line adjustment, the reverse correction amount is set as in the crosstalk adjustment,
As shown in FIG. 2, the DMD 18 allows LCD 15
The intensity of light that passes through is controlled in pixel units to correct the projected brightness level. In this case as well, since it occurs depending on the pattern of the input video signal 12 as in the case of the occurrence of crosstalk, the signal processing unit 13 recognizes the display pattern. It is detected whether the level exists, and in the area of the vertical line where the luminance level that is likely to occur is present, the area to be corrected and the correction amount are calculated and passed to the correction processing unit 22. These have the effect of improving ghosts and vertical lines.

Next, a third embodiment of the present invention will be described with reference to FIG. In this case, the transmitted light from the transmissive liquid crystal display panel 31 is obliquely incident on and reflected by the surface of the DMD element 32. Where DMD
The basic structure of the element 32 is almost the same as that described in FIG. 1, but the partition 7 of the DMD element 2 shown in FIG. 1 does not exist.

As shown in FIG. 3, the transmitted light 33, 33a, 33b that has passed through the transmissive liquid crystal display panel 31 is obliquely incident on the DMD element 32, reflected by the surface of the micromirror, and reflected light 34, 34a, respectively. 34b. In this way, the video pixels 35, 35a, 35b are formed.
In this case, the angle change of the micromirror surface of the DMD element 32 is the same as that described with reference to FIG. In this way, the ON state and the OFF state are created, and the brightness level is controlled by the pulse width modulation. Even in such a reflective liquid crystal display device, the same effect as that described in the first embodiment can be obtained.

The reflective liquid crystal display device of the present invention can be similarly applied to a display device other than the liquid crystal projector or a color liquid crystal display device.

The present invention is not limited to the above-mentioned embodiments, and the embodiments can be appropriately modified within the scope of the technical idea of the present invention.

[0032]

As described above, according to the present invention, the transmissive liquid crystal display panel and the DMD element disposed on the back side of the transmissive liquid crystal display panel are used, and the illumination light is used for the transmissive liquid crystal display. The brightness is adjusted through the micromirror surface of the DMD element through the panel. here,
The brightness is adjusted by pulse width modulation. In this way, the luminance unevenness of the transmitted light of each predetermined LCD pixel is adjusted, and the luminance level of the transmitted light of the LCD pixel is corrected in pixel units to perform flicker adjustment or crosstalk adjustment. It is like this.

Further, according to the present invention, the display pattern is recognized by the signal processing unit from the input video signal of the image, the correction pattern and the correction amount are calculated by the correction processing unit, and the DMD element is driven to perform the flicker adjustment or the flicker adjustment. It is designed to adjust crosstalk.

As described above, according to the present invention, highly accurate luminance unevenness correction and flicker, crosstalk, and ghost adjustment can be easily performed. Further, the present invention provides a high-quality image adjusted with high accuracy in a liquid crystal display device, and further provides an adjustment system automated with high accuracy in a liquid crystal projector.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a basic structure portion of a reflective liquid crystal display device for explaining a first embodiment of the present invention.

FIG. 2 is a block diagram showing a basic configuration of a liquid crystal projector for explaining the first or second embodiment of the present invention.

FIG. 3 is a sectional view of a basic structure portion of a reflective liquid crystal display device for explaining a third embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view of a reflective liquid crystal display panel for explaining a conventional technique.

FIG. 5 is a schematic cross-sectional view of a reflective display device for explaining a conventional technique.

[Explanation of symbols]

1, 31 Transmissive liquid crystal display panel 2, 32 DMD element 3, 107 Substrate 4, 4a, 4b, 108, 108a, 108b Micro mirror 5, 109 Hinge 6,110 Stopper 7 Partition wall 8, 8a, 8b, 111, 111a, 111b Incident light 9, 9a, 9b, 34, 34a, 34b, 112, 11
2a, 112b Reflected light 10, 10a, 10b, 35, 35a, 35b, 11
3, 113a, 113b Image pixel 11 Image forming unit 12 Input image signal 13 Signal processing unit 14 LCD driving unit 15 LCD 16 Lamp 17 PBS 18 DMD 19 Projection lens 20 Screen 21 CCD camera 22 Correction processing unit 23 DMD driving unit 24 Memory 25 Photodetectors 33, 33a, 33b Transmitted light 101, 102 Glass substrate 103 Liquid crystal layer 104 Reflective pixel electrode 105 Reflective liquid crystal display panel 106 DMD

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G09G 3/20 G09G 3/20 680H 5G435 3/34 3/34 D 3/36 3/36 F term (reference) ) 2H041 AA12 AB14 AC06 AZ00 2H091 FA14Z FA41Z GA11 LA18 LA20 2H093 NA61 NC14 NC49 NC53 NC62 NC66 NC68 ND07 ND17 ND58 5C006 BB16 EA03 EC11 FA22 FA23 5C080 AA10 AA18 BB05 DD05 DD06 DD15JJ1016022816282802

Claims (7)

[Claims] 1. A transmissive liquid crystal display panel and a DMD (Digit
al Micro-mirror Device) element, and the brightness of the transmitted light from the transmissive liquid crystal display panel is adjusted by the DMD element. 2. A transmissive liquid crystal display panel, and a DMD element arranged on the back side of the transmissive liquid crystal display panel,
After passing through the transmissive liquid crystal display panel, the illumination light is vertically incident on the micromirror surface of the DMD element, further vertically reflected, and irradiates the transmissive liquid crystal display panel again. Characteristic liquid crystal display device. 3. The liquid crystal display device according to claim 2, wherein a partition wall that absorbs light is provided around each micromirror of the DMD element. 4. Each LCD of the transmissive liquid crystal display panel
4. The liquid crystal display device according to claim 1, wherein the micromirrors of the DMD element are provided in a one-to-one correspondence with (Liquid Crystal Display) pixels. 5. A predetermined LC is adjusted by adjusting an angle of the micromirror surface with respect to an optical axis of the transmitted light or incident light.
The liquid crystal display device according to claim 4, wherein the brightness of the transmitted light of the D pixel is adjusted. 6. The liquid crystal display device according to claim 5, wherein the brightness level of the transmitted light of the LCD pixel is corrected in pixel units, and flicker adjustment, crosstalk adjustment, or ghost adjustment is performed. 7. A display pattern is recognized from an input video signal by a signal processing unit, the correction pattern and correction amount of the brightness are calculated by the correction processing unit, and the DMD element is driven to adjust the flicker and crosstalk. Alternatively, the ghost adjustment is performed, and the liquid crystal display device according to claim 6.