JP2003177426A - Liquid crystal panel and projection type display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for obtaining the same black frame display as in the case that a parting line is provided around a pixel region in a reflection type active matrix liquid crystal panel. <P>SOLUTION: In the reflection type active matrix liquid crystal panel, an electrically conductive layer to be a parting electrode (28) is formed around the pixel region (22) of the substrate at the reflection side (20). Alternating voltage is applied from the electrically conductive layer to liquid crystal so that the liquid crystal held between a transparent common electrode (11) provided in a counter substrate (10) and the electrically conductive layer carries out the display of a black level. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type active matrix liquid crystal panel and a driving method thereof, and more particularly to a reflection type liquid crystal panel suitable for use as a light valve of a projection type display device and a projection type display device using the same. Regarding

[0002]

2. Description of the Related Art Conventionally, as an active matrix liquid crystal panel, a TFT array using amorphous silicon is formed on a glass substrate in a one-to-one correspondence with pixel electrodes.
Therefore, a liquid crystal panel having a structure in which a drive voltage is applied to the pixel electrode has been put into practical use.

The active matrix liquid crystal panel is classified into a reflective type and a transmissive type, and the reflective active matrix liquid crystal panel has the following advantages over the transmissive active matrix liquid crystal panel. Formed below the pixel electrodes are portions that do not directly contribute to display, such as signal lines (source lines or data lines), scanning lines (gate lines), wirings such as capacitance lines, pixel driving transistors (TFTs), and storage capacitors. As a result, a substantially high aperture ratio can be obtained. For the above reason, the aperture ratio does not decrease even if the wiring is thickened, so that the wiring resistance can be reduced and a good display can be performed. In the case of the reflection type, a TFT or MOSFET array having a large driving ability is formed on an insulating substrate or a semiconductor substrate, and a pixel electrode serving as a reflection electrode is further formed on the TFT or MOSFET array, and a driving voltage is applied by the transistor. You can In particular, in the case of the structure in which the MOSFET is formed on the semiconductor substrate, the silicon IC process can be used, and therefore fine processing is possible. Therefore, it is possible to obtain a compact, high-definition and bright display as compared with the transmissive type, and therefore, it is attracting attention as a light valve of a projector.

[0004]

However, in the reflection type active matrix liquid crystal panel, the device size is required to be smaller than that of the transmission type in order to increase the reflection intensity of light. In the liquid crystal panel, it is necessary to provide a light blocking member for a parting (a mask for hiding the peripheral edge of the display screen) on the counter substrate side. However, when the panel size becomes small, the relative light blocking member and the pixel region are provided. There is a problem that alignment becomes difficult.

Therefore, the present inventor has studied a technique for forming a parting line in a reflective active matrix liquid crystal panel. As a result, it became clear that there are the following problems.

In the case of a negative mode such as an SH liquid crystal mode using SH (Super Homeotropic) liquid crystal, black display occurs when no voltage is applied to the liquid crystal, so that the liquid crystal around the pixel region is normally aligned. The display becomes black regardless of whether the periphery of the transistor side substrate is in the reflective state or the non-reflective state, and the function as a parting off can be obtained. However, in the SH liquid crystal mode, it is necessary to vertically align the liquid crystal, and it is extremely difficult to perform uniform vertical alignment processing by the conventional technique, and thus it is difficult to completely display the surroundings in black. The liquid crystal material with negative dielectric anisotropy used in SH liquid crystal mode is TN (Tw
Compared to the positive dielectric anisotropy liquid crystal materials used in isted Nematic) liquid crystal mode, there are few types, the usable temperature range is narrow, and the reliability is poor.

On the other hand, since a liquid crystal panel of the TN liquid crystal mode can be manufactured by a proven existing technology, there is no problem in terms of reliability. However, when a reflection type liquid crystal panel of the TN liquid crystal mode is incorporated in a projection type display device, a positive display is provided, so that a white contour appears around the display portion unless a partition is provided around the pixel region. There is.

An object of the present invention is to provide a technique capable of displaying a black frame in a reflective active matrix liquid crystal panel, which is similar to the case where a partition is provided around the pixel area.

Another object of the present invention is to enable display of a black frame similar to the case where a parting is provided without complicating the process.

[0010]

In order to achieve the above object, the present invention provides a reflective active matrix liquid crystal panel in which a light-shielding conductive layer is formed around a pixel region of a reflective side substrate and An alternating voltage is applied to the liquid crystal held between the counter electrode and the display level in the black direction. As a result, it is possible to perform a black frame display surrounding a pixel area similar to the case of a parting. Moreover, since the conductive layer is formed on the opposite substrate, the alignment accuracy is higher than that of the light-shielding member formed on the opposite substrate side, and display defects (white contours) due to misalignment can be avoided. it can. The present invention is particularly effective when the display mode of the liquid crystal panel is positive display.

A dummy pixel column composed of a dummy pixel electrode that does not contribute to display and a switching element that applies a drive voltage to the electrode is arranged around the pixel region, and the counter substrate is provided on the dummy pixel electrode. An alternating voltage for displaying a black level is applied to the liquid crystal held between the liquid crystal and the transparent common electrode. Conventionally, a technique of providing a dummy pixel electrode in order to prevent display unevenness at the periphery of the pixel region has been known, and the present invention uses the dummy pixel electrode to perform a black frame display as a cutoff, thereby performing no process. The above object can be achieved without modification. Of course, the conductive layer for displaying the black frame may be formed on the outside of the dummy pixel electrode to apply an AC voltage for displaying black level to the liquid crystal.

Further, a switching element array is formed in a one-to-one relationship with the pixel electrodes on the reflection side substrate, a driving voltage is applied to the pixel electrodes via the switching elements, and a peripheral circuit including switching elements such as transistors is provided around the pixel electrodes. In the provided reflective active matrix liquid crystal panel, the conductive layer is formed of a light-shielding material so as to cover the peripheral circuit. As a result, it is possible to prevent the circuit from malfunctioning due to a leak current flowing through the switching element due to the incident light. The conductive layer and the dummy pixel electrode may be formed of the same material as the pixel electrode in the pixel region at the same time. Further, antireflection treatment may be applied to the surfaces of the conductive layer and the dummy pixel electrode.

The AC voltage applied to the liquid crystal by the conductive layer is an AC voltage having substantially the same positive and negative amplitude centered on the common potential applied to the counter electrode, and is applied to the liquid crystal by the dummy pixel electrode. The AC voltage is preferably an AC voltage having substantially the same positive and negative amplitude centered on the center potential of the signal applied to the counter electrode.
This is to prevent a DC voltage from being applied to the liquid crystal over time. The AC voltage is the same as or shorter than the polarity inversion cycle of the polarity of the voltage applied to one pixel, preferably 100 kHz or less of the commercial power supply and 100 kHz or less that is lower than the response speed of the liquid crystal. Is.
The frequency of 50 Hz or higher is for preventing flicker.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

1 to 3 show a first embodiment of a reflection type active matrix liquid crystal panel to which the present invention is applied. Among these, FIG. 1 shows a plane layout of a reflection side substrate on which pixel electrodes and transistors are formed, FIG. 2 shows a sectional configuration of the entire liquid crystal panel, and FIG. 3A shows an enlarged sectional view of a part of a pixel region. FIG. 3B shows an equivalent circuit diagram of one pixel.
1 to 3, 10 is a glass substrate that serves as a substrate on the incident side, 20 is a glass substrate that is a substrate on the reflecting side, 30 is a TN liquid crystal sealed between the substrates, and 31 is a sealing material. As shown in FIG. 1, in this embodiment, a pixel area 22 formed by forming pixel electrodes 21 in a matrix is provided in the center of a reflection side substrate 20, and image data is provided on a signal line around the pixel area 22. Line driver circuit 2 for supplying
3 or a selected scanning line driving circuit 24 for sequentially selecting the scanning lines 4 to which the gates of thin film transistors (TFTs) as switching elements for applying the voltage on the signal lines to the pixel electrodes are connected, and from the outside via the pad region 25. A peripheral circuit including an input circuit 26 for taking in input image data and a timing control circuit 27 for controlling these circuits is provided.

The peripheral circuit is constructed by using a transistor formed in the same step as the transistor for applying a voltage to the pixel electrode 21 as an active element or a switching element, and combining this with a load element such as a resistor or a capacitor. . In this embodiment, around the pixel region 22,
A parting electrode 28, which is a conductive layer also serving as a light-shielding layer for preventing light from entering the peripheral circuit, is provided. The shape of the inner end of the parting electrode 28, that is, the shape of the opening, is made to substantially match the outer shape of the pixel region 22. Pad area 25 for inputting signals from outside or supplying power supply voltage
Is positioned so that it is outside the sealing material 31.

As shown in FIG. 2, the glass substrate 1 on the incident side is provided.
LC on the inner surface of 0 (lower surface in the figure) is the opposite potential of the liquid crystal.
A common electrode 11 made of a transparent conductive film (ITO) to which a common potential is applied is provided, and the glass substrate 20 on the reflection side is provided.
The glass substrate 10 on the incident side and the incident side are arranged with an appropriate interval, and TN (Tw
An isted Nematic) type liquid crystal 30 is enclosed to form a liquid crystal panel.

Here, the LC common potential (LC-C
OM is a voltage applied to the common electrode 11 which is opposed to the pixel electrode 21 with the liquid crystal 30 interposed therebetween, and is a so-called pushdown (a parasitic capacitance charge of a transistor flows to the pixel electrode side) which is a problem in driving the liquid crystal. This is a voltage preliminarily shifted by that amount in consideration of the phenomenon that the substantial writing voltage shifts to the minus side. That is, the parasitic capacitance CTr of the transistor, the liquid crystal capacitance CLCD of the pixel, the charge holding capacitance CH of the pixel
, When the voltage amplitude Vg of the scanning signal applied to the gate of the transistor is {CTr / (CTr + CLCD + CH)} × V
Since a charge corresponding to the voltage g flows into the pixel during the non-conduction period (non-selection period) of the transistor, the voltage applied to the liquid crystal drops. Therefore, this voltage is applied to the amplitude center potential of the image signal and the common electrode. Bias potential LC-COM.

The common electrode 11 is formed wider than the pixel region 22 so as to face the pixel electrode 21 of the pixel region 22 and the parting electrode 28 on the peripheral circuit via the liquid crystal 30. Moreover, in this embodiment, although not particularly limited, the parting electrode 25 is formed of a metal layer such as aluminum formed in the same step as the pixel electrode 21. This can simplify the process. In addition, the pixel region 22 and the parting electrode 2
It is possible to reduce the distance from the substrate 8 to the minimum processing dimension of the process, and to avoid the positional shift due to the mask misalignment.

As shown in FIG. 3A, a semiconductor layer 41 made of polysilicon or the like, which will be the operation region of the TFT, is formed in an island shape on the surface of the glass substrate 20 on the reflection side. A scanning line / gate electrode 42 composed of a second layer of polysilicon or a multilayer of polysilicon and a refractory metal is formed on the upper surface of the glass substrate 20 from above the scanning line / gate electrode 12. An interlayer insulating film 43 such as a PSG film is formed on the surface. Further, a signal line 44 made of a metal layer such as aluminum is formed on the interlayer insulating film 43. The signal line 44 is a contact hole formed in the interlayer insulating film 43, and the signal line 44 is a gate electrode of the semiconductor layer 41. It is connected to the source (or drain) region located on the side of 42.

On the signal line 44 and the interlayer insulating film 43, L made of an insulating material such as silicon dioxide is used.
A flattening film 45 made of a TO (Low Temperature Oxide) film or an SOG film formed by spin coating is formed, and a pixel electrode 21 made of a metal such as a second aluminum layer is formed on the flattening film 45. A part of the pixel electrode 21 formed is electrically connected to the drain (or source) region of the TFT through a contact hole formed in the flattening film 45 and the interlayer insulating film 43.
Further, FIG. 3B is an equivalent circuit diagram of one pixel.
A storage capacitor 46 (not shown in FIG. 3A) is connected to the TFT of each pixel. Although not shown, an alignment film for aligning the enclosed liquid crystal is formed on the surface of the pixel electrode 21 (upper surface in the drawing) and the surface of the common electrode 11 (lower surface in the drawing).

When the LTO film is used as the interlayer insulating film 43, the pixel electrode 21 is ground by the CMP (Chemical Mechanical Polishing) method to planarize the LTO film, and when the SOG film is used. After baking (baking) the coated film, for example, by low temperature sputtering, one side is about 20μ.
It is shaped like a square of m. The pixel electrode 21
Is not limited to aluminum, and may be any material as long as it is a conductor having high reflectance. Further, the surface of the pixel electrode 21 may be polished by the CMP method to further increase the reflectance.

On the other hand, in the above embodiment, the parting electrode 28 provided around the pixel region 22 and covering the peripheral circuit is formed of the same metal as the pixel electrode 21 such as aluminum.
It may be formed of a conductor other than aluminum. Further, since the parting electrode 28 does not need to reflect the incident light and it is better to scatter or absorb the incident light, the surface of the parting electrode 28 is clouded by, for example, an etching process, or C
The antireflection treatment may be performed by forming an r layer or the like.

In the liquid crystal panel of this embodiment, the LC common potential LC-COM is applied to the common electrode 11, and the parting electrode 28 is LC-CO as shown in FIG.
A voltage Va having an amplitude that is substantially symmetrical in positive and negative directions with respect to M is applied. This voltage Va is transmitted through the polarizing element when linearly polarized light is incident from the incident side substrate 10, is reflected by the parting electrode 28, and is incident on the polarizing element located outside the incident side substrate 10. At least 10%
Hereinafter, a voltage of 0.5% or less, more specifically, a voltage Va at a level of the saturation voltage on the black side in the transmittance characteristic is applied (see FIG. 4C). Figure 4 (c)
FIG. 9 is a transmittance vs. applied voltage characteristic diagram of light transmitted through the polarizing element to the liquid crystal in a configuration in which a polarizing element that allows reflected light from the liquid crystal panel to enter the outside of the incident side substrate. In this figure, the polarization axis of the polarizing element is set so as to be in the positive mode. As a result, an AC voltage is applied to the liquid crystal present between the parting electrode 28 above the peripheral circuit and the common electrode 11, and the incident light with the liquid crystal molecules in a vertical state is reflected by the parting electrode 28 as it is. get out. On the other hand, in the pixel electrode to which no voltage is applied, the liquid crystal molecules remain twisted, and the incident polarized light is reflected by the pixel electrode, and the polarization axis is rotated by 90 ° and then exits.

As described above, the liquid crystal panel of the above-described embodiment is configured to perform a positive display, that is, a display in which a portion to which a voltage is applied becomes black when incorporated in a projection display device described later. Therefore, when an AC voltage is applied to the parting electrode 28 formed so as to surround the pixel region 22 as described above, that part becomes a black level display, and a parting light blocking member is formed on the incident side substrate. Instead, it is possible to display a black frame having the same function as that of the parting, and the alignment accuracy with the pixel region 22 is improved,
It is possible to avoid a display defect (occurrence of a white contour) due to misalignment. If the parting electrode is not driven, the liquid crystal driving region becomes discontinuous at the boundary between the pixel region and the parting electrode, and display noise occurs. However, in the present embodiment, the liquid crystal in the pixel region and the parting electrode region is not Since both are AC-driven, the occurrence of display unevenness can be suppressed.

When the light shielding member is arranged outside the counter substrate, the opening end of the light shielding member may be aligned with the parting electrode 28, and the alignment accuracy of the light shielding member may be low. Easy to assemble. In addition, the black display of the parting can be performed by the combination of the light shielding member and the black level display in the parting electrode region, so that the light leakage can be further reduced.

In the above embodiments, the TFT has been described as a transistor element of a pixel. However, the reflection side substrate is a semiconductor substrate, a MOSFET is formed on the semiconductor substrate, and transistors of pixels and peripheral circuits are MOSFETs. Good.

As the switching element, a two-terminal type non-linear element such as MIM may be used instead of the transistor.

5 and 6 show a second embodiment of a reflection type active matrix liquid crystal panel to which the present invention is applied.

In this embodiment, a dummy pixel region in which a plurality of columns of dummy pixel electrodes 29 that do not contribute to the original display are formed around the pixel region 22 of the reflection side substrate 20 is provided. On the other hand, the peripheral edge on the outer surface (upper surface in the figure) side of the counter substrate 10 is made of a resin material having a low reflectance or is Cr on the surface.
A light shielding member 12 formed with a (chrome) film or the like is joined so as to cover the peripheral circuit outside the dummy pixel region from the middle thereof. That is, in this embodiment, the inner end (opening end) of the light shielding member 12 is designed to be located in the dummy pixel region. Then, an AC voltage is applied to the dummy pixel electrode 29 similarly to the parting electrode 28 in the first embodiment.

In the liquid crystal panel of the first embodiment, the LC common potential applied to the common electrode formed on the counter substrate is applied to the parting electrode formed around the pixel region where the pixel electrode of the reflection side substrate is formed. , The voltage is applied so as to have a waveform having substantially the same positive and negative amplitude, but in the second embodiment in which the dummy pixel is provided, the amplitude center potential Vb of the image signal supplied to the signal line is On the other hand, it is preferable to apply the voltage Vc (see FIG. 4B) having a waveform having substantially the same positive and negative amplitude to the signal line to which the dummy pixel electrode is connected. In the embodiment, the dummy pixel has the same structure as the display pixel, and the dummy pixel electrode is also configured such that the voltage is applied by the transistors provided in a one-to-one correspondence like the display pixel electrode. Therefore, the push-down caused by the parasitic capacitance of the transistor is generated in the same manner as the pixel. Therefore, the voltage supplied to the dummy pixel is also changed at the same amplitude center as the display pixel, and the DC voltage is applied between the dummy pixel electrode and the common electrode. I'm trying not to continue.

The dummy pixels are not limited to two columns and may be any number of columns. Normally, 6 rows are enough.

By providing dummy pixels around the display pixels, not only the close-up display can be performed. Since the boundary between the pixel area and the dummy pixel area does not become discontinuous when driving the liquid crystal (that is, the area where the liquid crystal is driven together), conventionally, it occurs at the boundary between the pixel area and the peripheral area where the liquid crystal is not driven. However, display unevenness that affects display in the pixel region can be suppressed in the vicinity of the pixel region, and display image quality can be improved.

Even if the light blocking member is provided, the inner edge of the light blocking member may be disposed on the dummy pixel electrode region, and the light blocking member does not have to be aligned with the peripheral edge of the pixel region. Will be easier. In addition, the black display can be performed by the combination of the light blocking member and the black level display in the dummy electrode region, so that light leakage can be further reduced.

As the switching element, a two-terminal type non-linear element such as MIM may be used instead of the transistor.

The transistor may be a TFT or a MOSFET, as in the first embodiment. The surface of the dummy pixel electrode may be subjected to antireflection treatment as in the parting electrode of the first embodiment.

7 and 8 show a third embodiment of a reflection type active matrix liquid crystal panel to which the present invention is applied.

In this embodiment, a dummy pixel region in which a plurality of columns of dummy pixel electrodes 29 that do not contribute to the original display are formed is provided around the pixel region 22 of the reflection side substrate 20, and the first embodiment is further provided outside thereof. A parting electrode 28 similar to the example is provided. Then, on the dummy pixel electrode 29,
Similar to the second embodiment, a voltage Vc having a waveform having substantially the same positive and negative amplitude with respect to the amplitude center potential of the image signal is applied to the parting electrode 28 formed around the dummy pixel region. As in the first embodiment, a voltage Va having a waveform having substantially the same positive and negative amplitude as the LC common potential applied to the common electrode formed on the counter substrate is applied. .

Incidentally, as in the first and second embodiments, the third
Also in the embodiment, the display unevenness in the vicinity of the periphery of the pixel area is reduced, so that the image quality can be improved.

Further, when the light shielding member is arranged outside the counter substrate, the opening end of the light shielding member may be aligned with the dummy electrode or the parting electrode, and the alignment accuracy of the light shielding member may be low. Therefore, the assembly becomes easy. In addition, the black display of the parting off can be performed by the combination of the light shielding member and the black level display on the dummy electrode region and / or the parting off electrode region, so that the light leakage can be further reduced.

The transistor may be a TFT or a MOSFET, as in the above-mentioned embodiment, and may be a MIM or the like.
It may be replaced with a terminal type non-linear element.

Further, the surface of the dummy pixel electrode and / or the parting electrode may be subjected to antireflection treatment as in the first embodiment.

FIG. 9 shows a configuration example of a projector as an example of a projection type display device to which the reflection type liquid crystal panel of the above-mentioned embodiment is applied as a light valve.

In FIG. 9, 100 is a lamp as a light source, 101 is a reflection mirror, and 102A and 102B are right-angle prisms. The two right-angled prisms have a polarization beam splitter layer 102a at the interface and are bonded with an adhesive to form a cube prism. This adhesive has a refractive index closer to that of the prism.
The polarization beam splitter layer 102a selectively transmits S-polarized light of the light from the light source 100 and selectively reflects P-polarized light component. Of course, this polarization component splitter may be configured to transmit the P polarization component and reflect the S polarization component.

Reference numeral 103 denotes a dichroic mirror that transmits only the wavelength component of red light and reflects other components (green and blue light), and 104 denotes a dichroic mirror that reflects only green light and transmits other components (red and blue light), Reference numeral 105 is a dichroic mirror that transmits only blue light and reflects other components (green and red light), and 106, 107, and 108 are for red light, green light, and blue light using the reflective liquid crystal panel of the above embodiment. And 110 is a projection lens for projecting on the screen a color image which is modulated by each light valve and is composed of the respective color lights by the prism.

In the above structure, the light from the light source is separated, modulated, combined and projected as described below.

The light emitted from the light source 100 is reflected only by P-polarized light at the polarization splitter layer 102a, and the reflected P light is reflected.
The polarized component is incident on the dichroic mirror 103,
Only the wavelength component of red light is transmitted and the other wavelength components are reflected. As a result, red light is incident on the liquid crystal panel 106. On the other hand, the S-polarized light component transmitted through the polarization splitter layer 102a enters the dichroic mirror 104, reflects only the wavelength component of green light, and transmits other wavelength components. Therefore, the green light reflected by the dichroic mirror 104 enters the liquid crystal panel 107. Further, the color light transmitted through the dichroic mirror 104 includes not only the red light component but also the blue light component. Therefore, only the blue light is transmitted by the dichroic mirror 105 so that only the blue light is incident on the liquid crystal panel 108.

The liquid crystal panels 106, 107 and 108 are TN.
It is a reflection type liquid crystal panel that adopts type liquid crystal. When a TN type liquid crystal is adopted, in a pixel (OFF state) in which the applied voltage to the liquid crystal layer is almost 0, the incident color light is elliptically polarized by the liquid crystal layer, reflected by the pixel electrode, and re-ellipsed by the liquid crystal layer. Since it is polarized, it is almost 90
It is reflected and emitted as light with polarization axes that are deviated. On the other hand, in the pixel (ON state) to which the voltage is applied to the liquid crystal layer, the incident color light reaches the pixel electrode as it is, is reflected, and is reflected and emitted with the same polarization axis as at the time of incidence. In addition, since the alignment angle of the liquid crystal molecules of the TN type liquid crystal changes according to the voltage applied to the pixel electrode, the angle of the polarization axis of the reflected light with respect to the incident light depends on the voltage applied to the pixel electrode via the transistor of the pixel. It is variable according to.

For example, in the liquid crystal panel 106, when P-polarized red light is incident, in the case of the TN type liquid crystal, it is turned off.
State pixels are converted to S-polarized light and reflected / emitted, and ON-state pixels are reflected / emitted as P-polarized light. On the other hand, the liquid crystal panel 10
In S7 and S108, since S-polarized color light is incident, TN
In the case of the type liquid crystal, OFF-state pixels are converted into P-polarized light and reflected / emitted, and ON-state pixels are reflected / emitted as S-polarized light.

The red light reflected by the liquid crystal panel 106 passes through the dichroic mirror 103 and reaches the polarization beam splitter 102a which reflects the P-polarized component and transmits the S-polarized light.
Therefore, in the case of the TN type liquid crystal, the reflected light of the liquid crystal panel 106 is reflected by the OFF state pixel and the reflected light which is S-polarized is transmitted and reaches the projection lens 110, but is reflected by the P-polarized pixel of the ON state pixel. The light is reflected and does not reach the lens 110. By the above modulation control, the amount of transmitted light at 102a is controlled for each pixel in accordance with the voltage application to each pixel of the liquid crystal panel 106, and a red light image is formed. Since the green light and the blue light of the P-polarized light reflected by the polarization beam splitter 102a are reflected by the dichroic mirror 103 as P-polarized light, they are reflected by the polarization beam splitter 102a and do not reach the lens 110.

On the other hand, the liquid crystal panels 107 and 108
The color lights reflected by are combined by the dichroic mirror 104 and reach the polarization beam splitter 102a. Therefore, in the case of the TN type liquid crystal, the reflected light of the liquid crystal panels 107 and 108 reflects the reflected light that is P-polarized by the OFF state pixel and reaches the projection lens 110.
The polarized reflected light is transmitted and does not reach the lens 110. By the above modulation control, the amount of transmitted light at 102a is controlled for each pixel according to the voltage application to each pixel of the liquid crystal panel,
Images of green light and blue light are formed. Of the S-polarized light that has passed through the polarization beam splitter 102a, the blue light is reflected by the dichroic mirror 105 as it is as S-polarized light, and therefore passes through the polarization beam splitter 102a and does not reach the lens 110.

Therefore, by reflection / transmission by the polarization beam splitter 102a, a color image is formed by combining the images of the three primary colors formed on the liquid crystal panels 106 to 108, and the color image is projected onto the screen 110 by the projection lens 110. As a result, in the projection type projector of FIG. 9 in which the reflection type liquid crystal panel of the TN type liquid crystal is incorporated as a light valve, the reflected light of the OFF state pixel reaches the projection lens 110, so that the projection image on the screen is displayed in the positive mode. The Rukoto.

FIG. 10 shows an example of parameters such as the optimum rubbing direction (alignment treatment direction) of the alignment films of the element substrate (reflection-side substrate) and the counter substrate in the liquid crystal panel using the TN liquid crystal. . Of these, FIG. 10 (A) is shown in FIG.
Of the liquid crystal panels 106 to 108 in FIG. 9 are optimum for the panels 107 and 108 on which S-polarized light is incident, and FIG. 10B is the optimum parameter for a panel on which P-polarized light is incident such as the liquid crystal panel 106 in FIG. Each parameter is shown.

In the projector of FIG. 9 using the liquid crystal panels of the first and third embodiments, as described with reference to FIGS. 1 to 3, the periphery of the pixel area in which the pixel electrode of the reflection side substrate is formed is used. Is covered with a parting electrode and a voltage having an AC waveform with respect to the LC common potential applied to the common electrode formed on the counter substrate is applied, so that the periphery of the pixel region is displayed as a black frame. Since this functions as a parting line, it is not necessary to provide a light blocking member as a parting line on the counter substrate side. Alternatively, since the parting electrode has a light-shielding function even if the light-shielding member is provided, it is not necessary to align the light-shielding member with the end portion of the pixel region, and the inner end of the light-shielding member may be provided on the parting electrode. Positioning of the light shielding member becomes easy. Further, since the parting electrode is formed on the same substrate as the pixel electrode, the alignment accuracy between the pixel region and the parting region is improved, and display defects (occurrence of white contour) due to misalignment can be avoided. Furthermore, if the pixel electrode and the parting electrode are formed in the same process, the alignment becomes more accurate. Further, in the projector using the liquid crystal panel of the second embodiment, the dummy pixel electrode and the light shielding member integrally function as a parting line, and the light shielding member can prevent light from entering the peripheral circuits. It has an advantage that it cannot be obtained only with the dummy electrode.

In the above embodiment, a glass substrate is used as the reflection side substrate, and a so-called polysilicon TFT having polysilicon as an active layer formed on the glass substrate is used as a switching element for applying a voltage to the pixel electrode. However, it may be a liquid crystal panel in which a semiconductor wafer such as single crystal silicon is used as a substrate, and MOSFETs, pixel electrodes, etc. are formed on the substrate as the reflection side substrate. In addition, as an element for applying a voltage to the pixel electrode, a TFT
Not only the liquid crystal panel using MIM (Meta-Insulat
It is also applicable to a liquid crystal panel in which a two-terminal type non-linear element such as an or-metal) is used as an element for applying a voltage to a pixel electrode.

Furthermore, in the above-mentioned embodiment, the case of applying to the reflection type liquid crystal panel using the TN liquid crystal has been described.
The present invention can also be applied to a liquid crystal panel using an SH liquid crystal and having a polarizing plate provided on the incident side or a polymer dispersed liquid crystal panel.

[0057]

As described above, according to the present invention, in the reflective active matrix liquid crystal panel, the conductive layer is formed around the pixel region of the reflective side substrate, and the conductive layer is formed on the counter substrate, that is, the incident side substrate. Since the liquid crystal sandwiched between the provided transparent common electrode is applied with an AC voltage for displaying a black level, it is possible to perform a black frame display surrounding a pixel area similar to the case of a cutoff. Since the conductive layer is formed on the reflection-side substrate having the pixel electrode, there is an effect that the alignment accuracy becomes high and the display defect (occurrence of white contour) due to misalignment can be avoided. Further, since the parting can be performed by this conductive layer, the light shielding member can be omitted. Further, even if the light-shielding member is provided, the inner end of the light-shielding member may be disposed on the conductive layer, and the light-shielding member does not have to be aligned with the peripheral end portion of the pixel region, so that the alignment of the light-shielding member becomes easy.

In addition, a dummy pixel electrode that does not contribute to display and a switching element that applies a drive voltage to this electrode are arranged around the pixel region, and the dummy pixel electrode and the transparent common electrode provided on the counter substrate are connected. Since the alternating voltage is applied by the liquid crystal sandwiched between them so as to display a black level, it is possible to display a black frame as a cutoff by using these dummy pixel electrodes.

Further, a reflective active matrix in which a switching element is formed on the substrate in a one-to-one correspondence with a pixel electrode, a driving voltage is applied to the pixel electrode via the switching element, and a peripheral circuit made up of the switching element is provided around the pixel electrode. In the liquid crystal panel, since the conductive layer is formed so as to cover the peripheral circuit with a light-shielding material, it is possible to prevent the circuit from malfunctioning due to the leakage current flowing by the light incident on the switching element forming the peripheral circuit. There is an effect that can be.

Further, the conductive layer and the dummy pixel electrode are simultaneously formed of the same material as the pixel electrode in the pixel region, so that the process can be simplified.

Furthermore, by applying antireflection treatment to the surfaces of the conductive layer and the dummy pixel electrode, it is possible to obtain a parting with a higher contrast.

Further, as the voltage applied to the conductive layer, an AC voltage having substantially the same positive and negative amplitude centered on the common potential applied to the counter electrode is used, and the voltage applied to the dummy pixel electrode is used. Since the alternating voltage having substantially the same positive and negative amplitudes is used around the center potential of the image signal, it is possible to prevent the direct voltage from being applied to the liquid crystal.

[Brief description of drawings]

FIG. 1 is a plan layout view showing a first embodiment of a reflection side substrate of a reflection type liquid crystal panel to which the present invention is applied.

FIG. 2 is a cross-sectional view showing a first embodiment of a reflection side substrate of a reflection type liquid crystal panel to which the present invention is applied.

FIG. 3 is an enlarged cross-sectional view of a first embodiment of a reflective side substrate of a reflective liquid crystal panel to which the present invention is applied.

FIG. 4 is a waveform diagram showing an example of an AC voltage applied to a parting electrode and a dummy pixel electrode of a reflective liquid crystal panel to which the present invention is applied.

FIG. 5 is a plan layout view showing a second embodiment of a reflection side substrate of a reflection type liquid crystal panel to which the present invention is applied.

FIG. 6 is a cross-sectional view showing a second embodiment of a reflection side substrate of a reflection type liquid crystal panel to which the present invention is applied.

FIG. 7 is a plan layout view showing a third embodiment of a reflection side substrate of a reflection type liquid crystal panel to which the present invention is applied.

FIG. 8 is a sectional view showing a third embodiment of a reflection side substrate of a reflection type liquid crystal panel to which the present invention is applied.

FIG. 9 is a schematic configuration diagram of a projector as an example of a projection type display device to which the reflection type liquid crystal panel of the embodiment is applied as a light valve.

FIG. 10 is an explanatory diagram showing optimum rubbing directions of alignment films of an element substrate (reflection-side substrate) and a counter substrate in a reflective liquid crystal panel using TN liquid crystal.

[Explanation of symbols]

10 Counter substrate (incident side substrate) 11 common electrode 12 Light-shielding member to be closed 20 Reflection side substrate 21 Pixel electrode 22 pixel area 23 Signal line drive circuit 24 Scan line drive circuit 25 pad area 26 Input circuit 27 Timing control circuit 28 Close-up electrode 29 Dummy pixel electrode 30 liquid crystal 31 Seal material 41 Polysilicon layer (operating layer of MOSFET) 42 Scan line and gate electrode 43 Interlayer insulation film 44 signal line 45 flattening film 100 lamps 101,102 Right angle prism 103-105 dichroic mirror 106-108 reflective liquid crystal panel 110 Projection lens

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03B 21/00 G03B 21/00 EF term (reference) 2H088 EA12 HA01 HA02 HA03 HA06 HA08 HA13 HA14 HA18 HA20 HA21 HA23 HA24 HA28 JA04 JA05 MA20 2H091 FA05X FA07X FA10X FA14Y FA21X FA26X FA37X FA37Y FA41X GA01 GA02 GA06 GA13 HA06 HA07 JA01 LA30 MA07 2H092 HA04 JA03 JA24 JA34 JB22 JB31 NA31 PA16 NA31 PA16 PA13 PA16 PA13 PA16 PA13 PA16 PA13 PA16 PA13 PA16 PAA NE01 NE02 NE03 NE04 NE10 NF04 NF05 NF11 NG02 2K103 AA05 AB10 BB03 BC23

Claims (9)

[Claims] 1. A reflection side substrate having pixel regions in which pixel electrodes to be reflection electrodes are formed in a matrix and switching elements are formed corresponding to each reflection electrode, and an incident side transparent having a counter electrode. The substrates are arranged so as to face each other, and liquid crystal is sealed in a gap between the reflection side substrate and the transparent substrate, and a voltage is applied to the reflection electrode via the switching element. In the liquid crystal panel, a light-shielding conductive layer is formed around the pixel region of the reflection-side substrate, and a liquid crystal sandwiched between the conductive layer and the counter electrode makes a display in a black display level. A liquid crystal panel characterized in that an alternating voltage is applied. 2. The liquid crystal panel according to claim 1, wherein the conductive layer is formed in a ring shape. 3. The liquid crystal panel according to claim 1, wherein the conductive layer is formed on a peripheral circuit. 4. The liquid crystal panel according to claim 1, wherein the conductive layer is made of the same material as the pixel electrode. 5. The liquid crystal panel according to claim 1, wherein a surface of the conductive layer is antireflection-treated. 6. The voltage applied to the conductive layer is an AC voltage having substantially the same positive and negative amplitude centered on the potential applied to the counter electrode.
6. The liquid crystal panel according to any one of items 5 to 5. 7. The AC voltage according to claim 1, wherein the AC voltage is an AC voltage having a cycle that is the same as or shorter than an inversion cycle of a polarity of a voltage applied to one pixel. The described liquid crystal panel. 8. The liquid crystal panel according to claim 1, further comprising a polarizing means on the light emission side, wherein the light reflected by the conductive layer has a transmittance of 10 which is transmitted through the polarizing means.
The liquid crystal panel is characterized in that an AC voltage is applied to the liquid crystal sandwiched between the conductive layer and the counter electrode so as to be not more than%. 9. A light source, a liquid crystal panel having a structure according to claim 1, which modulates and reflects light from the light source, and collects light modulated by these liquid crystal panels. And a projection lens for projecting.