JP2012173489A - Electro-optical device, drive method for the electro-optical device, and electronic equipment - Google Patents

Electro-optical device, drive method for the electro-optical device, and electronic equipment Download PDF

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JP2012173489A
JP2012173489A JP2011034904A JP2011034904A JP2012173489A JP 2012173489 A JP2012173489 A JP 2012173489A JP 2011034904 A JP2011034904 A JP 2011034904A JP 2011034904 A JP2011034904 A JP 2011034904A JP 2012173489 A JP2012173489 A JP 2012173489A
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pixel
voltage
pixels
black
liquid crystal
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Kimiya Nagasawa
仁也 長澤
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Seiko Epson Corp
セイコーエプソン株式会社
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Abstract

PROBLEM TO BE SOLVED: To suppress deterioration of display quality near an edge terminal part of a display area.SOLUTION: In a display area to be an inside of a virtual line 200, display pixels 110a are arranged in a matrix. Outside the virtual line 200, a peripheral area is formed in such a way as encircling the display area, and light is shielded by a black matrix. In the peripheral area, dummy pixels 110b are arranged. Voltage to be applied to a pixel electrode is defined so that the dummy pixels 110b adjacent to the display pixels 110a among the dummy pixels 110b are disposed in an alternate arrangement where respective black and white pixels are arranged at every other pixel by turns every other pixel as viewed in the direction along a periphery of the display area.

Description

  The present invention relates to a technique for suppressing deterioration in display quality that is likely to occur at the edge of a display area.

An electro-optical device, such as a liquid crystal panel, has a configuration in which a pair of element substrates and a counter substrate are bonded together with a certain gap therebetween, and liquid crystal is sandwiched between the gaps. In the element substrate, pixel electrodes are arranged in a matrix for each pixel on the surface facing the counter substrate, while in the counter substrate, the common electrode is opposed to all the pixel electrodes on the surface facing the element substrate. Is provided.
In such a liquid crystal panel in which pixels are arranged in a matrix, dummy pixels that do not contribute to display are provided in a peripheral region surrounding the display region in order to uniformize the optical characteristics of the display region in which pixels that contribute to display are arranged. The technique to provide is proposed (refer patent document 1).
In addition, in order to prevent a display defect such that light leaks in the vicinity of the edge of the display area, a pixel electrode adjacent to the dummy pixel electrode among the pixel electrodes of the display area with respect to the pixel electrode of the dummy pixel. A technique for applying the same voltage is also proposed (see Patent Document 2).
On the other hand, it has been pointed out that ionic impurities contained in the liquid crystal deteriorate the display quality (see Patent Document 3).

JP-A-2005-241778 JP 2010-210734 A Japanese Patent Laid-Open No. 4-86812

However, even in the above technique, in addition to the problem that light still leaks near the edge of the display area, that is, the boundary between the inner side and the outer side of the display area, In the vicinity of the edge of the display, the deterioration of display quality, which seems to be caused by ionic impurities, began to be noticeable.
The present invention has been made in view of the above-described circumstances, and one of its purposes is to provide a technique capable of suppressing a reduction in display quality in the vicinity of an edge portion of a display area.

In order to achieve the above object, in the electro-optical device according to the present invention, an element substrate having a display area and a light-shielding area arranged so as to surround the display area and the element substrate are arranged to face the element substrate. Driving the counter substrate, the liquid crystal sandwiched in the gap between the element substrate and the counter substrate, the pixels provided corresponding to the display region, and the pixels provided corresponding to the light shielding region A driving circuit; and a light-shielding portion provided at a position overlapping with the light-shielding region in plan view. The element substrate includes a first pixel electrode provided corresponding to a pixel in the display region; and the light-shielding region. A second pixel electrode provided corresponding to the pixel, the counter substrate includes a common electrode to which a predetermined voltage is applied, and the driving circuit displays a display image with respect to the first pixel electrode. And applying a voltage according to the second pixel Of poles, with respect to the first pixel electrode in adjacent pixel electrode, and applying a white voltage and the black voltage to every other pixel as viewed in a direction along the periphery of the display area alternately.
According to the present invention, in the vicinity of the edge portion of the display region, it is possible to suppress a decrease in display quality due to impurities as well as light leakage.

In the present invention, it is preferable that the white voltage and the black voltage have a relative transmittance of 10% or less and 90% or more. In the present invention, the drive circuit applies the white voltage and the black voltage to the liquid crystal with respect to a pixel electrode provided corresponding to a corner portion of the light shielding region of the second pixel electrode. A configuration in which a higher voltage effective value is applied is preferable. According to this configuration, it is possible to make it difficult to return to the display area by moving the impurities that have moved from the display area to the corners.
Further, the drive circuit is configured to alternately replace a voltage applied to a pixel electrode adjacent to the first pixel electrode among the second pixel electrodes at a predetermined time interval between the white voltage and the black voltage. It is also good. With this configuration, white and black are alternately arranged temporally and spatially.
In addition, the drive circuit may be configured such that the second pixel electrodes applied to the white voltage or the black voltage are aligned radially outward as viewed from the display area. According to this configuration, it is possible to make it difficult for the impurities that have moved to the periphery of the display region to move to the light-shielding region outside the display region, even if they are not corners, and return to the display region.
On the other hand, the liquid crystal preferably has a normally black mode. In the normally black mode, a predetermined voltage applied to the common electrode or a voltage close thereto can be used as the black voltage.

  The present invention can be conceptualized as an electro-optical device, a driving method of the electro-optical device, and an electronic apparatus including the electro-optical device. As such an electronic apparatus, there is a projector that enlarges and projects a light modulation image by an electro-optical device.

1 is a block diagram illustrating a configuration of an electro-optical device according to an embodiment of the invention. FIG. It is a figure which shows the structure of the liquid crystal panel in an electro-optical apparatus. It is a figure which shows the equivalent circuit of the pixel in a liquid crystal panel. It is a figure for demonstrating the display area and peripheral area of a liquid crystal panel. It is a figure which shows the formation area of the black matrix in a liquid crystal panel. It is a figure which shows the applied voltage to the dummy pixel in the peripheral region of a liquid crystal panel. It is a figure for demonstrating the applied voltage to a dummy pixel. It is a figure for demonstrating the applied voltage to a dummy pixel. It is a figure which shows the drive waveform to a pixel. It is a figure which shows the drive waveform to a pixel. It is a figure which shows the applied voltage to the dummy pixel in a liquid crystal panel. It is a figure which shows the applied voltage to the dummy pixel in the liquid crystal panel which concerns on an application example. It is a figure which shows the applied voltage to the dummy pixel in the liquid crystal panel which concerns on an application example. It is a figure which shows the display characteristic in a liquid crystal panel. It is a figure for demonstrating a spot phenomenon. It is a figure for demonstrating a spot phenomenon. It is a figure for demonstrating a spot phenomenon. It is a figure for demonstrating a spot phenomenon. It is a figure which shows the structure of the projector to which the electro-optical apparatus is applied.

Embodiments of the present invention will be described below with reference to the drawings.
This embodiment is an electro-optical device used as a light valve of a projector. In the following drawings, the scales may be varied to make each layer, each member, each region, etc., recognizable.

FIG. 1 is a block diagram illustrating an overall configuration of the electro-optical device according to the embodiment. As shown in this figure, the electro-optical device 1 includes a control circuit 2, a memory 3, a D / A conversion circuit 4, and a liquid crystal panel 100.
Among these, the liquid crystal panel 100 is provided with a total of 20 scanning lines 112 of 16 rows plus 4 rows along the row (X) direction in the figure, while a total of 28 data lines 114 of 24 columns plus 4 columns. Are provided so as to be electrically insulated from each scanning line 112 along the column (Y) direction. The pixels 110 are arranged corresponding to the intersections of the 20 rows of scanning lines 112 and the 28 columns of data lines 114, respectively. Therefore, in this embodiment, the pixels 110 are arranged in a matrix of 20 rows × 28 columns. However, this arrangement is for simplification of explanation, and is not intended to limit the present invention to the arrangement.

Although details of the matrix arrangement of the pixels 110 will be described later, the pixels 110 for the two outer rounds are dummy pixels that do not contribute to display. However, dummy pixels are not distinguished from the display pixels that contribute to display because there is no particular difference in terms of electrical configuration.
Further, in the present embodiment, in order to distinguish between the scanning lines 112 and the rows of the pixels 110, a row, b row, 1 row, 2 rows,..., 16 rows, c row in FIG. , D rows, and in order to distinguish the columns of the data lines 114 and the pixels 110 in the same manner, in order from the left in FIG. 1, the a-th column, the b-th column, the first column, the second column,. These are called the column, the c-th column, and the d-th column.

  The liquid crystal panel 100 is a built-in peripheral circuit type in which a scanning line driving circuit 130 and a data line driving circuit 140 are formed around a region where pixels 110 are arranged in a matrix. Of these, the scanning line driving circuit 130 applies scanning signals Ga, Gb, G1, G2,..., G16, Gc, Gd to the scanning lines 112 of a, b, 1, 2,. To supply. Specifically, the scanning line driving circuit 130 sequentially selects the scanning lines 112 in accordance with the control signal supplied from the control circuit 2, and sets the scanning signal to the selected scanning line as the selection voltage of the H level (VH). The scanning signals for the other scanning lines are set to the L level (VL) non-selection voltage.

The data line driving circuit 140 includes a sampling signal output circuit 142 and a TFT (Thin Film Transistor) 144 provided for each data line 114.
Among these, the sampling signal output circuit 142 sequentially sequentially selects H, corresponding to the data lines 114 in the a, b, 1, 2,..., 24, c, and d columns each time the scanning line 112 is selected. Sampling signals Sa, Sb, S1, S2,..., S24, Sc, Sd are output.
The TFT 144 provided in each column has a source electrode connected to the signal line 146, a drain electrode connected to the data line 114 corresponding to the column, and a sampling signal corresponding to the column supplied to the gate electrode. .

Video data Da is supplied to the electro-optical device 1 in synchronization with the vertical scanning signal Vs, the horizontal scanning signal Hs, and the dot clock signal Clk from a host device (not shown). The video data Da is, for example, 8-bit digital data, and the shade (gradation value) of the pixel 110 is designated with 256 gradations from the darkest “0” to the brightest “255”.
The memory 3 is a dual port DRAM (Dynamic Random Access Memory) having a storage area corresponding to the pixels 110 arranged in 20 rows × 28 columns, and capable of executing storage and reading in parallel. In the memory 3, video data Da corresponding to each display pixel is stored in a storage area corresponding to the display area in accordance with an instruction from the control circuit 2. On the other hand, in the memory 3, a storage area corresponding to a dummy pixel in a peripheral area arranged so as to surround the display area (light-shielded by a black matrix 94 described later and corresponding to the “light-shielding area” of the present invention). The tone value “0” or “255” is preset as will be described later.
The video data Da is stored as a video data Db in response to a writing scan in the liquid crystal panel 100 after a predetermined period (a period of one frame or less) has elapsed since the video data Da was stored.

The D / A conversion circuit 4 converts the read video data Db into a data signal Vid having a voltage according to the gradation value and having a polarity specified by the polarity instruction signal Pol. Specifically, the D / A conversion circuit 4 converts the voltage Vc to the higher voltage when the positive polarity is instructed, and converts the voltage Vc to the lower voltage when the negative polarity is instructed. The signal is converted and output to the signal line 146 as the data signal Vid.
Note that the voltage Vc is the amplitude center potential of the data signal, is a reference for the writing polarity to the pixel 110, and is approximately an intermediate voltage between the power supply voltages VH and VL (see FIG. 10 described later). In other words, in the present embodiment, regarding the polarity of the data signal, the higher side than the voltage Vc has a positive polarity, and the lower side has a negative polarity. On the other hand, other voltages are based on the voltage VL (= Gnd) except for the holding voltage of the liquid crystal element described later.
The reason for inverting the polarity of the data signal is to drive the pixel AC. In the present embodiment, a surface inversion method is used in which the polarity of all pixels is inverted for each frame.

2A is a perspective view showing the structure of the liquid crystal panel 100, and FIG. 2B is a cross-sectional view taken along line Hh in FIG. 2A.
As shown in these drawings, the liquid crystal panel 100 includes a device substrate 101 on which a pixel electrode 118 is formed and a counter substrate 102 on which a common electrode 108 is provided by a sealing material 90 including a spacer (not shown). While being bonded so that the electrode forming surfaces face each other while maintaining a certain gap, for example, a VA (Vertical Alignment) type liquid crystal 105 is sandwiched in this gap.

  As the element substrate 101 and the counter substrate 102, substrates having optical transparency such as glass and quartz are used. In the element substrate 101, the size in the Y direction in FIG. 2A is longer than the counter substrate 102, but the back side (h side) is aligned, so the near side (H side) of the element substrate 101. One side protrudes from the counter substrate 102. In this protruding area, a plurality of terminals 107 are provided along the X direction. The plurality of terminals 107 are connected to an FPC (Flexible Printed Circuits) substrate and supplied with various signals from the control circuit 2 and the like.

A pixel electrode 118 is formed on a surface of the element substrate 101 facing the counter substrate 102. The pixel electrode 118 is formed by patterning a conductive metal having transparency such as ITO (Indium Tin Oxide) into a rectangular shape. In addition, in the element substrate 101, a scanning line driving circuit 130 is formed in addition to the data line driving circuit 140 in the periphery where the pixel electrodes 118 are arranged. However, in FIG. 2B, the scanning line driving circuit 130 and the data line driving circuit 140 are not shown.
On the other hand, in the counter substrate 102, the common electrode 108 provided on the surface facing the element substrate 101 is a solid conductive metal having transparency such as ITO.

  The counter substrate 102 is provided with a black matrix 94 as will be described in detail later. Further, the sealing material 90 is formed in a frame shape along the inner edge of the counter substrate 102, and a part of the sealing material 90 is opened to inject the liquid crystal 105. For this reason, after the liquid crystal 105 is injected, the opening is sealed with the sealing material 92. Further, the opposing surface of the element substrate 101 and the opposing surface of the counter substrate 102 are respectively provided with alignment films for aligning liquid crystal molecules along the normal direction of the substrate surface when no voltage is applied. FIG. Is omitted.

FIG. 3 is a diagram illustrating an equivalent circuit of the pixel 110. As shown in this figure, each pixel 110 includes an n-channel TFT 116, a liquid crystal element 120, and an auxiliary capacitor 125. Regardless of whether each pixel 110 contributes to display as described above or not, it has the same configuration when viewed electrically.
Here, when attention is paid to a certain row and a certain column, for the pixel 110 corresponding to the target row and the target column, the gate electrode of the TFT 116 is connected to the scanning line 112 of the target row, while its source The electrode is connected to the data line 114 of the target column, and the drain electrode thereof is connected to the pixel electrode 118 and the electrode 62 forming one end of the auxiliary capacitor 125.
The common electrode 108 is common to all the pixels 110 and is maintained at the voltage LCcom in this embodiment.

As described above, the liquid crystal panel 100 has a structure in which the liquid crystal 105 is sandwiched between the element substrate 101 and the counter substrate 102. For this reason, the liquid crystal element 120 has a configuration in which the liquid crystal 105 as a dielectric is sandwiched between the pixel electrode 118 formed on the opposing surface of the element substrate 101 and the common electrode 108 formed on the opposing surface of the opposing substrate 102. Since the liquid crystal 105 is of the VA type as described above, in the present embodiment, it is set to a normally black mode that becomes black when no voltage is applied.
The other end of the auxiliary capacitor 125 is a capacitor electrode 115, and is commonly connected across the pixels 110 to the capacitor wiring 72 to which the voltage LCcom is applied. For this reason, the auxiliary capacitor 125 is connected in parallel to the liquid crystal element 120 for each pixel 110.

FIG. 4 is a plan view for explaining the arrangement of pixels in the present embodiment. In this figure, pixels that are simply indicated by square frames are pixels, and as described above, they are arranged in a matrix of 20 rows × 28 columns.
Among these, the one corresponding to the intersection of 1 to 20 rows excluding a, b, c and d rows and 1 to 24 columns excluding a, b, c and d columns contributes to the display. It is a display pixel.
On the other hand, the pixels corresponding to the intersections of the a, b, c, and d rows and the a, b, c, and d columns are dummy pixels that do not contribute to display.
In the figure, a frame-like virtual line 200 is used for the purpose of partitioning a display area 200a in which display pixels contributing to display are arranged and a peripheral area 200b in which dummy pixels are arranged.

Note that there is no difference between the display pixel and the dummy pixel in terms of the electrical configuration. Therefore, when not distinguished, the pixel is denoted as the pixel 110. However, in FIG. 4, the display pixel is denoted as 110a so as to be distinguished. For the dummy pixels, the reference numeral is 110b.
When distinguishing the pixels, the pixel electrode (first pixel electrode) of the display pixel 110a is denoted by 118a, and the pixel electrode (second pixel electrode) of the dummy pixel 110b is denoted by 118b. I will decide.

FIG. 5 is a diagram showing a region where the black matrix (light-shielding portion) 94 is formed on the counter substrate 102 when the substrate is viewed in plan.
As shown in this figure, in the display area 200a inside the virtual line 200, the black matrix 94 is provided in a lattice shape so as to shield the gap between pixels. On the other hand, the black matrix 94 is provided over the entire surface in the peripheral region 200 b outside the virtual line 200.

In such a configuration, when the scanning line driving circuit 130 sets the scanning signal to a certain scanning line 112 to the H level, the TFT 116 whose gate electrode is connected to the scanning line 112 is turned on, and the pixel electrode 118 is turned on. The data line 114 is electrically connected. For this reason, when the data line driving circuit 140 supplies a data signal having a voltage corresponding to the gradation value to the data line 114 when the scanning line 112 is at the H level, the data signal is turned on. Is applied to the pixel electrode 118 via When the scanning line 112 becomes L level, the TFT 116 is turned off, but the voltage applied to the pixel electrode 118 is held by the capacitive element of the liquid crystal element 120 and the auxiliary capacitor 125.
The scanning line driving circuit 130 selects the scanning lines 112 in the order of rows a, b, 1, 2,..., 16, c, and d, while the data line driving circuit 140 is positioned on the selected scanning line 112. By supplying a data signal to the pixels for one row through the data line 114, a voltage corresponding to the gradation value is applied to and held in the liquid crystal element 120. This operation is repeated every frame (one vertical scanning period).
In the liquid crystal element 120, the molecular alignment state of the liquid crystal 105 changes according to the voltage held by the pixel electrode 118 and the common electrode 108, that is, the strength of the electric field generated at both electrodes.

  In FIG. 2B, light incident from the counter substrate 102 side is emitted to the element substrate 101 side along the path of the common electrode 108, the liquid crystal 105, and the pixel electrode 118. At this time, the ratio of the amount of light emitted to the amount of light incident on the liquid crystal element 120, that is, the transmittance increases as the voltage applied to and held by the liquid crystal element 120 increases. As described above, in the liquid crystal panel 100, since the transmittance changes for each liquid crystal element 120, the liquid crystal element 120 corresponding to the intersection of the 1st to 16th rows and the 1st to 24th columns belonging to the display area is the minimum unit of an image to be displayed. It functions as a certain pixel.

By the way, since the dummy pixel 110b is shielded from light by the black matrix 94, even if the transmittance of the liquid crystal element 120 in the peripheral region 200b is changed, it should not affect the image displayed in the display region 200a. However, in actuality, light incident from an oblique direction with respect to the normal direction of the substrate is transmitted through the liquid crystal element 120 of the dummy pixel 110b and has a considerable influence on the display image. For this reason, in order to prevent light in an oblique direction from being visually recognized on the observation side, a configuration in which all the dummy pixels 110b are black with the minimum transmittance can be considered.
However, in this configuration, when a white pixel and a black pixel are adjacent to each other, a horizontal electric field in a direction parallel to the substrate surface is generated due to a potential difference between the pixel electrodes. The liquid crystal 105 should be driven only by a vertical electric field in a direction perpendicular to the substrate surface. However, if a horizontal electric field is applied, the alignment of the liquid crystal is disturbed (domain is generated), resulting in a display defect. Appear. As miniaturization and higher definition progress in recent years and the gap between pixel electrodes becomes narrower, the influence of the transverse electric field is more prominent.
For this reason, in the configuration in which all the dummy pixels 110b are black, when the display pixel 110a located at the edge (outer peripheral edge) of the display area turns white due to the display image, the black pixel and the white pixel are adjacent to each other. As a result, a display defect appears at the edge of the display image, and the display quality is degraded.

On the other hand, in the configuration in which all the dummy pixels 110b are white, when the display pixel 110a located at the edge of the display area becomes black due to the display image, the black pixel and the white pixel are adjacent to each other. Since there is no change, not only display defects appear in the same way, but incident light from an oblique direction cannot be blocked in the first place.
In view of this, a configuration has been proposed in which all the dummy pixels 110b have an intermediate gray color between black and white. In this configuration, the influence of the lateral electric field can be reduced regardless of whether the display pixel 110a located at the edge of the display area becomes white or black, and incident light from an oblique direction is incident on the liquid crystal element of the dummy pixel 110b. This is because it can be prevented to a certain extent through 120.
Here, in the normally black mode, the relationship between the applied voltage and the transmittance of the liquid crystal element 120 is expressed by a V (voltage) -T (transmittance) characteristic shown in FIG. At this time, it is only necessary to apply to the pixel electrode 118 of the dummy pixel 110b a voltage such that the effective voltage value held in the liquid crystal element 120 is Vgr at the point P having the maximum inclination in the VT characteristic.
In FIG. 14, the minimum transmittance is normalized to 0% and the maximum transmittance is normalized to 100%.

However, in the configuration in which all the dummy pixels 110b are grayed out, a display defect due to a cause other than the domain occurs. Specifically, as shown in FIG. 15A, all of the dummy pixels 110b are grayed out, and in the display area, the rectangular white area as well as the rectangular white area are respectively displayed in the vertical and horizontal directions. As shown in FIG. 15B, the lower left corner of a part of the white area is different from the original white color when an image arranged alternately is displayed. There was a problem with the display as if it were stained with a dark color.
Note that this display defect is referred to as “stain” for the sake of convenience in order to distinguish it from that caused by the domain. Further, the dummy pixel 110b is not actually visible because it is shielded from light by the black matrix 94, but the black matrix 94 is present in FIGS. 15A and 15B for convenience of explanation. It shows the display state when it is assumed that no.

Now, as shown in FIG. 15B, the stain does not occur in all of the white areas arranged alternately. Therefore, in order to specify the condition for causing the stain, the white region is located in the three regions close to the stain occurrence portion, that is, the region located on the left side, the region located on the lower left side, and the lower side. Patterns with different densities were displayed for each region, and it was examined whether or not spots were generated in the white region. The results are as shown in FIGS. 16 (a) to 16 (d).
That is, when the left adjacent region, the lower left region, and the lower adjacent region are gray as shown in FIG. 16 (a) with respect to the white region, as shown in FIG. 16 (b), When the lower left area is gray and the lower adjacent area is black, and when the left adjacent area is black and the lower left area and the lower adjacent area are gray as shown in FIG. A spot occurs in the lower left corner of the white area. On the other hand, as shown in FIG. 16 (d), even if the left adjacent region and the lower adjacent region are black with respect to the white region, the stain does not occur if the lower left region is white.

Here, a lower left corner portion where a spot is generated in the white region coincides with the alignment direction of the liquid crystal in the element substrate.
On the other hand, in the liquid crystal panel 100 in which the liquid crystal 105 is sandwiched between the element substrate 101 and the counter substrate 102, ions that are mixed when the liquid crystal 105 is sealed or eluted from the sealing material 90 that surrounds the liquid crystal 105. It is known that volatile impurities aggregate in the display area by subsequent driving (Japanese Patent Laid-Open No. 4-86812).
Then, next, the cause of the occurrence of the stain will be discussed with reference to FIGS. 17 and 18 in association with the movement of the liquid crystal and the movement of the impurities.

17A is a plan view of the arrangement of the pixels 110 from the element substrate 101 side, and FIG. 18 is a cross-sectional view taken along line Qa-Qb in FIG. It is a figure which shows when the pixel of black display has been arranged in the orientation direction.
In this embodiment, since the liquid crystal panel 100 is in a normally black mode using the VA type as the liquid crystal 105, as shown in FIG. 18, in the black display pixel 110, between the pixel electrode 118 and the common electrode 108. The magnitude of the electric field generated in is close to zero. Therefore, the long axis of the liquid crystal molecules 105a is aligned in the direction perpendicular to the substrate surface. At this time, the liquid crystal molecules 105a are given a slight tilt angle (pretilt) with respect to the normal of the substrate surface by the alignment film 97 on the element substrate 101 side and the alignment film 98 provided on the counter substrate 102 side. ing.
The reason why the pretilt is given by the alignment films 97 and 98 is as follows. That is, when the electric field changes from a state close to zero to a strong electric field, if the pretilt is not applied, the liquid crystal molecules 105a are difficult to tilt all at once, but if the pretilt is applied, the liquid crystal molecules 105a are pretilted. This is because it becomes easy to incline all at once from the state toward the parallel direction of the substrate surface, so that a good optical response can be expected.
Further, such alignment films 97 and 98 are formed by vapor growth of a plurality of minute columnar structures inclined in the same direction by oblique deposition of an inorganic material such as silicon oxide. In this description, the alignment direction of the liquid crystal is a direction in which the liquid crystal molecules are tilted when the electric field becomes strong, as a direction when projected onto the substrate surface.

  On the other hand, as the electric field generated between the pixel electrode 118 and the common electrode 108 becomes stronger, the major axis of the liquid crystal molecules 105a is gradually inclined from the pretilt state toward the direction parallel to the substrate surface. In the white display pixel 110, since the electric field is maximized, the long axis of the liquid crystal molecules 105a is most inclined with respect to the normal of the substrate surface, as shown by the solid line in FIG.

By the way, the voltage to the pixel electrode 118 is applied during the selection period, and in the liquid crystal element 120, an electric field corresponding to the potential difference between the pixel electrode 118 and the common electrode 108 is generated. The electric field gradually weakens due to off-leakage or the like. For this reason, the electric field generated between the pixel electrode 118 and the common electrode 108 in the liquid crystal element 120 changes greatly during the selection period, and gradually decreases during the non-selection period.
The liquid crystal molecules 105a are tilted as indicated by a solid line when a voltage is applied during the selection period, but move back in the vertical direction of the substrate surface as indicated by a broken line due to a leak during the non-selection period. At this time, the speed at which the liquid crystal molecules 105a are tilted by the voltage application in the selection period is larger than the return speed in the non-selection period as shown by the size of the rotating arrow in the figure. For this reason, the liquid crystal molecules 105a are repeatedly tilted at a high speed toward the parallel direction of the substrate surface by voltage application during the selection period, and then returned at a low speed toward the vertical direction of the substrate surface. Conceivable.
Actually, the liquid crystal molecules do not respond instantaneously according to the strength of the electric field, but seem to swing with a certain time difference.

In the white pixel, since the liquid crystal molecules existing in the middle of the alignment films 97 and 98 (substrates) oscillate around the center of gravity, the force for moving the impurities in the horizontal direction is the left and right in the figure. Directions cancel each other. For this reason, impurities do not move.
On the other hand, since one end of the liquid crystal molecules existing in the vicinity of the interface with the alignment films 97 and 98 is fixed by anchoring of the alignment film, the other end is greatly shaken when tilting. For this reason, in the vicinity of the element substrate 101 on the observation side, a flow in the direction from Qa to Qb, that is, the alignment direction occurs, and the impurities are moved to the left in the drawing.
On the other hand, on the opposite substrate side, the direction is from Qb to Qa. Therefore, when viewed as the whole panel, the forces for moving the impurities cancel each other and are zero.

On the other hand, in the black pixel, since the magnitude of the electric field due to voltage application during the selection period is close to zero, the liquid crystal molecules 105a are pre-tilted with respect to the vertical direction of the substrate surface, and off-leakage occurs during the non-selection period. But almost no return. For this reason, in the black pixel, as shown in FIG. 18, the liquid crystal molecules 105a hardly oscillate while maintaining a substantially upright state.
Therefore, the impurity moved by the white pixel is prevented from moving by the black pixel. Here, as shown in FIG. 17B, when the white pixel is located at three positions downstream in the alignment direction, that is, the left, lower left, and lower adjacent pixels are black pixels, the white pixels are moved by the white pixels. Impurities are lost due to the upright of the liquid crystal molecules by the black pixels, and stay in the white pixels, particularly in the lower left corner. It is considered that the staying impurities are visually recognized as a stain by reducing the transmittance of the white pixel.
As shown in FIG. 16A, FIG. 16B, and FIG. 16C, even if the three downstream positions in the alignment direction are not black pixels but gray pixels with respect to white pixels, Spots occur in white pixels. For this reason, it is considered that the gray pixel also has a function of blocking the impurities moved by the white pixel because the oscillation of the liquid crystal molecules is small.

  On the other hand, as shown in FIG. 16 (d), even if the left and lower neighbors are black areas among the three areas on the downstream side in the alignment direction with respect to the white areas, if the lower left is a white area, No spots occur. This is thought to be because, as shown in FIG. 17C, the impurities moved by the white pixels on the upstream side hardly flow and stay in the lower left pixels on the downstream side.

Further, the voltage LCcom applied to the common electrode 108 is relative to the voltage Vc which is the center of amplitude of AC driving so that a DC component is not applied to the liquid crystal 105 in consideration of push-down of the TFT 116 and light leakage in the display pixel 110a. Is set to be slightly lower (see FIG. 10). In other words, the voltage LCcom is optimized based on the display area 200a.
On the other hand, since the dummy pixel 110b is shielded from light by the black matrix 94, the degree of light leakage of the TFT 116 is different from that of the display region 200a. For this reason, the voltage LCcom optimized with reference to the display area 200a is a factor in which a DC component is applied to the liquid crystal 105, conversely, in the peripheral area 200b. For this reason, the influence of ionic impurities tends to be a problem in the vicinity of the peripheral region 200b.

Now, if the cause of the stain is that the impurities moved by the white pixels are blocked by three black pixels or ash pixels at the downstream side in the alignment direction and stay in large numbers, all the dummy pixels 110b are A white pixel that can release impurities can be used. However, if all of the dummy pixels 110b are white pixels, as described above, a domain due to a lateral electric field is generated. Further, even if all of the dummy pixels 110b are gray pixels, 2 × 2 pixels of two display pixels 110a and two dummy pixels 110b adjacent to these two display pixels 110a in the vertical or horizontal direction are When the conditions shown in FIG. 16A, FIG. 16B, or FIG. 16C are satisfied, a spot is generated.
Therefore, in the present embodiment, in order to prevent the display pixel 110a from being stained in any display state, as shown in FIG. 6, in the peripheral region 200b in which ionic impurities are likely to be a problem, As the dummy pixel 110b, white pixels and black pixels are arranged every other pixel.

Specifically, first, the dummy pixels 110b included in the corner portions 201 at the four corners in the peripheral region 200b are set as white pixels.
Next, white pixels and black pixels are arranged as follows for the dummy pixels (first circumference) adjacent to the display pixels 110 a outside the virtual line 200. That is, among the dummy pixels 110b that are adjacent to each other outside the virtual line 200, the dummy pixels 110b in the b rows, b columns, b rows c columns, c rows b columns, and c rows c columns included in the corner portions 201 at the four corners are white pixels. As a starting point, black pixels and white pixels are alternately arranged toward the vertical or horizontal center line of the display area. If the number of rows or columns of the display area is a multiple of 4 as in the present embodiment, as shown in FIG. 6, two white pixels as dummy pixels 110b are located across the center line. become.
In such an arrangement, if the number of rows or columns in the display area is an odd number, the vertical or horizontal center line of the display area becomes a black pixel or a white pixel, and two black pixels are consecutive. Not shown (not shown).
However, in this arrangement, if the number of rows or columns in the display area is an even number and not a multiple of 4, two black pixels as dummy pixels 110b are vertically aligned as shown in FIG. Or it will be located across the horizontal center line. At this time, for example, if the display pixel 110a in the 14 row and 12 matrix of the display area is white and the display pixel 110a in the 14 row and 11 column adjacent to the right is black, a stain is generated in the display pixel 110a in the 14 row and 12 matrix. End up.
Therefore, if the number of rows in the display area is an even number and is not a multiple of 4, one of the four corners, the upper end side or the lower end side, is set as the starting point of the alternating arrangement, and the black pixels, white Pixels are arranged alternately. Similarly, if the number of columns in the display area is an even number and is not a multiple of 4, one of the four corners, the left end side or the right end side, is the starting point of the alternating arrangement, and black pixels and white pixels are directed toward the other side. Arrange them alternately. FIG. 8 shows an example in which when the number of rows in the display area is 14 and the number of columns is 22, the upper left b and b columns and the lower right c and c columns are used as the starting points of white pixels. It is.

In this way, after defining the arrangement of the dummy pixels 110b in the first circumference adjacent to each other outside the imaginary line 200, the remaining dummy pixels 110b are also defined as white pixels and black pixels as follows. That is, the second circumference adjacent to the outside of the dummy pixel 110b on the first circumference has the same color as the dummy pixel 110b on the first circumference adjacent in the horizontal or vertical direction.
In this embodiment, the dummy pixels 110b located outside the virtual line 200 are only in the first and second rounds, but the same applies to the case where they are provided after the third round. Further, the dummy pixel 110b only needs to have the first round, and the second and subsequent rounds are arbitrary.

In the present embodiment, the display pixel 110 a and the dummy pixel 110 b are in a state corresponding to the gradation value stored in the storage area of the memory 3. Therefore, in order to bring the dummy pixels into the state shown in FIG. 6, the gradation value “255” is set for the dummy pixel 110b to be white, and the gradation value “0” is set for the dummy pixel 110b to be black. Just preset it.
For this reason, FIG. 6 shows not only the arrangement of the dummy pixels 110 b but also the gradation values preset in the memory 3.

Next, the operation of the electro-optical device 1 described above will be described. First, the storing operation in the memory 3 will be described.
The video data Da is supplied from the host device in synchronization with the vertical scanning signal Vs and the horizontal scanning signal Hs. Specifically, the dots in the order of 1 row 1 column to 1 row 24 column, 2 rows 1 column to 2 rows 24 columns, 3 rows 1 column to 3 rows 24 columns, ..., 16 rows 1 column to 16 rows 24 columns It is supplied for each pixel by a clock signal Clk.
As shown in FIG. 6, the memory 3 has a storage area corresponding to the pixels 110 arranged in 20 rows × 28 columns including the peripheral area.
The control circuit 2 sequentially stores the video data Da supplied from the host device in an area corresponding to the display pixel 110a in the memory 3.
On the other hand, in the area corresponding to the dummy pixel 110b in the memory 3, the gradation value “255” corresponding to the white pixel or the gradation value “0” corresponding to the black pixel as shown in FIG. It is preset with the specified arrangement.

When the control circuit 2 stores the video data Da corresponding to the pixels in a certain frame from the first row and the first column to the 16th row and the 24th column in the memory 3, the control circuit 2 performs control until the video data Da of the next frame is started to be supplied from the host device The circuit 2 starts the sequential reading of the video data Db from the memory 3. Note that the storage destination of the video data Da is only the storage area corresponding to the display pixel 110a, but the readout source of the video data Db corresponds to not only the storage area corresponding to the display pixel 110a but also the dummy pixel 110b. A storage area is also included.
Therefore, the video data Db is read in the order of a, b, 1, 2,..., 16, c, d rows. Further, each row is read out pixel by pixel in the order of a, b, 1, 2,..., 24, c, and d columns.
Note that the frame (supply system) defined by the supply of the video data Da and the frame (panel system) defined by the reading of the video data Db are not exactly the same, and define the supply of the video data Da. The frame defining the reading of the video data Db is delayed with respect to the frame. However, the period length itself is common at 16.7 milliseconds (when the vertical scanning frequency is 60 Hz).

  The control circuit 2 instructs the scanning line driving circuit 130 to select the scanning line 112 corresponding to the row of the video data Db being read.

FIG. 9 is a diagram showing waveforms of the scanning signals Ga, Gb, G1, G2,..., G16, Gc, Gd output by the scanning line driving circuit 130, and is sequentially delayed by the horizontal scanning period (H). It becomes H level.
In the figure, the H level of the scanning signal is the voltage VH, and the L level is the voltage VL. In the present embodiment, the voltage VL corresponding to the L level is actually the ground potential Gnd and the voltage zero as described above, and is a voltage reference.
In this embodiment, since the surface inversion method is used, the logic level of the polarity instruction signal Pol is inverted every frame. Here, the period in which the polarity instruction signal Pol is at the H level and the positive polarity writing is designated is referred to as an n frame for convenience, and the polarity indication signal Pol is at the L level and the negative polarity writing is designated. This period is called (n + 1) frames for convenience.
In order to generalize and describe the scanning signal, the scanning signal when no row is specified will be denoted as Gi.

  Further, the control circuit 2 instructs the sampling signal output circuit 142 to output a sampling signal corresponding to the column of the video data Db being read.

  FIG. 10 is a diagram showing waveforms of sampling signals Sa, Sb, S1, S2,..., S23, S24, Sc, Sd, etc. output by the sampling signal output circuit 142, and a certain scanning signal Gi is H level. Over the horizontal scanning period (H), the video data Db for one pixel is sequentially delayed for each period and is exclusively set to the H level.

  Now, from the memory 3, at the beginning of the panel frame, the video data Db for one row located in the a-th row is read in the order of a, b, 1, 2,..., 24, c, d columns. It is. Here, since the a-th line is all the dummy pixels 110b, the video data Db read from the memory 3 is either the white level with the gradation value “255” or the black level with the gradation value “0”. It is. If the frame is an n frame in which the positive polarity is designated by the polarity designation signal Pol, the video data Db is converted into the data signal Vid of the voltage Vw (+) by the D / A conversion circuit 4 if it is white level. If converted to a black level, it is converted to a data signal Vid of voltage Vb (+) and output to the signal line 146.

When the video data Db of row a and column a is read from the memory 3, the video data Db is converted into a data signal Vid and output to the signal line 146. At this time, the sampling signal output circuit 142 sets the sampling signal Sa to the H level and turns on the TFT 144 corresponding to the a column. As a result, the data signal Vid of the a row and the a column supplied to the signal line 146 is sampled to the data line 114 of the a column.
Similarly, the video data Db in the a-th row and b, 1, 2,..., 23, 24, c, and d columns is read from the memory 3 and output to the signal line 146 as the data signal Vid. Accordingly, the sampling signal output circuit 142 sequentially sets the sampling signals Sb, S1, S2,..., S23, S24, Sc, and Sd to the H level. As a result, the TFTs 144 in each column are turned on in order, and the data signal Vid of a row b column, a row 1 column, a row 2 column,..., A row 24 column, a row c column, a row d column is b. , 1, 2,..., 23, 24, c, and d are sampled on the data lines 114 respectively.
On the other hand, during the period when the video data Db for one row located in the a-th row is read from the memory 3, the scanning line driving circuit 130 sets the scanning signal Ga to the H level and is located in the a-th row. The TFT 116 in the dummy pixel 110b is turned on. Therefore, the data signal Vid sampled on the data line 114 in each column is applied to the pixel electrode 118b in the dummy pixel 110b in the a-th row.
Thereby, the dummy pixel 110b in the a-th row is in a white state or a black state according to the gradation value preset in the memory 3 as shown in FIG. However, since the a-th line is shielded from light by the black matrix 94, it is not directly recognized.

Next, the video data Db for one row located in the b-th row is similarly read from the memory 3 in the order of columns a, b, 1, 2,..., 23, 24, c, d. The data signal Vi d is converted and sampled on the data lines 114 in the a, b, 1, 2,..., 23, 24, c, and d columns. During the period when the b-th row of video data Db is read from the memory 3, the scanning line driving circuit 130 sets the scanning signal Gb to the H level. Therefore, the data signal Vid sampled on the data line 114 in each column is applied to the pixel electrode 118b in the dummy pixel 110b in the b-th row.
Accordingly, the dummy pixel 110b in the b-th row is in a white state or a black state in accordance with the gradation value preset in the memory 3 as in the a-th row, but is blocked by the black matrix 94. It is not directly visible.

Subsequently, the video data Db for one row located in the first row is similarly read from the memory 3 in the order of columns a, b, 1, 2,..., 23, 24, c, d. It is converted into the data signal Vid and sampled on the data lines 114 in the a, b, 1, 2,..., 23, 24, c, and d columns, respectively.
During the period when the video data Db in the first row is read from the memory 3, the scanning line driving circuit 130 sets the scanning signal G1 to the H level. Therefore, the data signal Vid sampled on the data line 114 in each column is applied to the pixel electrode 118 in the pixel 110 in the first row.
Here, in the first row, the a column and the b column are the dummy pixels 110b in which the black level of the gradation value “0” is preset, and thus are in the black state.
On the other hand, since the first to 24th columns in the first row are display pixels 110a, the transmittance corresponds to the gradation value designated by the video data Da.
In the first row, the c column and the d column are black because the dummy pixel 110b is preset with the black level of the gradation value “0”.

Thereafter, the same operation is repeated from the second line to the 16th line.
The dummy pixels 110b in the a, b, c, and d columns are in the white state in the second row and in the black state in the third row. Thereafter, the white pixels and the black pixels are alternately inverted, and the eighth row Becomes white. The dummy pixel 110b is in the white state again in the ninth row, and thereafter, the black pixel and the white pixel are alternately inverted, and in the 16th row, the dummy pixel 110b is in the black state.

Next, the video data Db for one row located in the c-th row is read from the memory 3 in the same column order and converted into the data signal Vid. Since all the c-th lines are the dummy pixels 110b, the white state corresponding to the gradation value “255” specified by the video data Db read from the memory 3 or the black state corresponding to the gradation value “0”. become.
The same applies to the d-th row.

Here, when the scanning signal Gi becomes the H level in the n frame in which the positive polarity writing is designated, the data signal Vid is, for example, any one of (a), (b), and (c) in FIG. The waveform is as shown. That is, in the selection period of the a, b, c, and d rows, as shown in FIG. 10A, the data signal Vid is a voltage Vw (+) corresponding to white, according to the output of the sampling signal, or The voltage Vb (+) corresponding to black is obtained.
In the selection period of the first, third, fifth, seventh, tenth, twelfth, fourteenth and sixteenth rows, the data signal Vid is as shown in FIG. That is, the data signal Vid corresponding to the dummy pixels 110b in the a, b, c, and d columns becomes the voltage Vb (+) corresponding to black, and the data signal Vid corresponding to the display pixels 110a in the 1 to 24 columns is As indicated by the upward arrow in the figure, the specified gradation value is higher (brighter) in the range from the voltage Vb (+) corresponding to black to the voltage Vw (+) corresponding to white. As a result, the positive polarity voltage becomes higher than the voltage Vc.
On the other hand, in the selection period of the second, fourth, sixth, eighth, ninth, eleventh, thirteenth, and fifteenth rows, the data signal Vid is as shown in FIG. That is, the data signal Vid corresponding to the dummy pixels 110b in the a, b, c, and d columns becomes the voltage Vb (+) corresponding to white, and the data signal Vid corresponding to the display pixels 110a in the 1 to 24 columns is It becomes a positive voltage according to the gradation.

In the next (n + 1) frame, the same operation is performed except that the polarity designation signal Pol becomes L level and the write polarity is designated as negative polarity. In the (n + 1) frame in which negative polarity writing is specified, the data signal Vid has a waveform as shown in any of FIGS. 10 (d), 10 (e), and 10 (f). That is, in the selection period of the a, b, c, and d rows, as shown in FIG. 10D, the data signal Vid is a voltage Vw (−) corresponding to white or a voltage Vb corresponding to black. (-)become.
Further, in the selection period of the first, third, fifth, seventh, tenth, twelfth, fourteenth and sixteenth rows, as shown in FIG. 10 (e), it corresponds to the dummy pixels 110b in the a, b, c and d columns. The data signal Vid becomes a voltage Vb (-) corresponding to black, and the data signal Vid corresponding to the display pixels 110a in the 1st to 24th columns is a voltage Vb corresponding to black as indicated by a downward arrow in the figure. In the range from (−) to the voltage Vw (−) corresponding to white, the negative polarity voltage becomes lower than the voltage Vc as the designated gradation value becomes higher (brighter).
On the other hand, in the selection period of the second, fourth, sixth, eighth, ninth, eleventh, thirteenth, and fifteenth rows, as shown in FIG. 10 (f), it corresponds to the dummy pixels 110b in the a, b, c, and d columns. The data signal Vid becomes a voltage Vb (−) corresponding to white, and the data signal Vid corresponding to the display pixels 110a in the 1st to 24th columns becomes a negative voltage corresponding to the gradation.

  The control circuit 2, the memory 3, the D / A conversion circuit 4, the scanning line driving circuit 130, and the data line driving circuit 140 are driven to apply a predetermined voltage to the pixel electrode 118a of the display pixel 110a and the pixel electrode 118b of the dummy pixel 110b. It will function as a circuit.

  In the present embodiment, since the dummy pixels 110b adjacent to the display area 200a are driven in an alternating arrangement of white pixels and black pixels, a stain generation pattern (see FIG. b) is avoided. For this reason, according to the present embodiment, it is possible to suppress the occurrence of spots near the edge of the display area 200a.

In particular, in the present embodiment, a total of four dummy pixels 110b of 2 × 2 are used as white pixels at the four corners 201 of the peripheral region 200b. For this reason, impurities that tend to stay in the four corners of the display area 200a are driven to the dummy pixels 110b that are white pixels in the corner portions 201, and the impurities are difficult to return to the display area 200a.
Further, the first periphery dummy pixels 110b adjacent to the display area 200a are alternately arranged with white pixels and black pixels, and the second periphery dummy pixels 110b adjacent in the vertical or horizontal direction with respect to the first periphery are also The same color as the adjacent first dummy pixels. For this reason, the white pixels and black pixels in the peripheral area 200b are radially expanded outward as viewed from the display area 200a. Therefore, even at the edge portion of the display area 200a, the white pixels have impurities that are different from the black pixels. While moving outward along the boundary, it is difficult to return.
Therefore, when such driving is continued for a certain period of time, impurities existing in the display region 200a are driven to the peripheral region 200b. For this reason, even if it becomes a generation pattern of a stain in the display area 200a, it is possible to suppress the visible appearance as a stain because the accumulated impurities are reduced.

  In this embodiment, the dummy pixels 110b adjacent to the display area 200a are alternately arranged with white pixels and black pixels. However, the edge of the display image is alternately arranged with black pixels and white pixels unless it is artificial. Is unlikely to be. For this reason, it is difficult to place a portion where a horizontal electric field is generated at the boundary between the display region 200a and the peripheral region 200b, and a situation in which a deterioration in display quality due to the occurrence of a domain is conspicuous can be avoided.

The present invention is not limited to the above-described embodiments, and the following applications and modifications are possible.
For example, in the embodiment, the white pixel and the black pixel are fixedly arranged with respect to the dummy pixel 110b.
In addition, when it is set as the structure which switches a white pixel and a black pixel with respect to the dummy pixel 110b, it may not be applied simply. For example, in the arrangement shown in FIG. 6, when white pixels and black pixels are exchanged except for the corner portion 201 of the peripheral region 200b, the arrangement shown in FIG. 11 is obtained, and two black pixels are vertically or They are arranged across the horizontal center line. At this time, for example, if the display pixel 110a in the 14 row and 12 matrix of the display area is white and the display pixel 110a in the 14 row and 11 column adjacent to the right is black, a stain is generated in the display pixel 110a in the 14 row and 12 matrix. As described above.
Therefore, in this case, the arrangement shown in FIG. 12 and the arrangement shown in FIG. 13 may be switched alternately. Specifically, after the array shown in FIG. 12 is driven with positive and negative polarities, the array shown in FIG. 13 may be similarly driven with positive and negative polarities.
In this way, when the white pixel and the black pixel are switched with respect to the dummy pixel 110b, white and black are alternately arranged temporally and spatially, so that the state of the alternating arrangement becomes difficult to be visually recognized. Further, it is considered that the portion where the horizontal electric field is generated at the edge portion of the display area 200a becomes difficult to continue.

In the embodiment, for the dummy pixel 110b, the white voltage corresponding to the gradation value “255” is applied to the pixel electrode 118b to maximize the transmittance of the liquid crystal element 120, or the gradation value “0”. The black voltage is applied to the pixel electrode 118b to minimize the transmittance of the liquid crystal element 120. However, the present invention is not limited to this.
Here, the biggest reason for arranging the dummy pixels 110b in the first circumference alternately in white and black is to avoid the occurrence pattern shown in FIG. 17B with the display pixels in the display area. It is to do.
At this time, the function required for the white pixel is to generate a flow that moves the impurities in the vicinity of the alignment film, and the function required for the black pixel is to prevent leakage light that cannot be prevented mainly by the white pixel, Even if the display pixel 110a continues to be black at the edge of the display area 200a, it becomes a weir that blocks the impurity moved by the white pixel and leads to the outside of the display area 200a. The white dummy pixel 110b is made discontinuous so that the influence of the transverse electric field is made discrete.

Therefore, if such a function is ensured, it is not always necessary to maximize the transmittance or minimize the transmittance.
Therefore, first, the execution of the function of the white pixel in the dummy pixel 110b will be considered. In the normally black mode, as shown in FIG. 14, a voltage with which the relative transmittance a (0 ≦ a ≦ 100) is 90% or more is applied to and held in the liquid crystal element 120 and AC driving is performed. For example, it can be expected that the liquid crystal molecules sufficiently oscillate, thereby generating a flow that moves the impurities. Here, the effective voltage value held in the liquid crystal element 120 when the relative transmittance is 90% is defined as Vth1. At this time, in order to execute a function corresponding to white in the dummy pixel 110b, a voltage (white voltage) such that the effective voltage value held in the liquid crystal element 120 is equal to or higher than Vth1 is set to the pixel electrode of the dummy pixel 110b. It is only necessary to apply a positive polarity and a negative polarity to 118b.
Next, consideration will be given to executing the function of the black pixel in the dummy pixel 110b. If only the function of blocking the impurities moved by the white pixel is considered, the voltage held in the liquid crystal element 120 can be determined from the consideration in FIGS. 16A, 16B, and 16C. It can also be realized by making the effective value Vgr gray. Further, if the dummy pixel 110b is gray, it is considered that the influence of the lateral electric field can be made discrete.
However, what is important for the black pixel in the dummy pixel 110b is the function of preventing leakage light that cannot be prevented by the white pixel. For this reason, as shown in FIG. 14, it is considered that leakage light can be prevented if a voltage with a relative transmittance of 10% or less is applied to and held in the liquid crystal element 120 and AC driving is performed. Here, the effective voltage value held in the liquid crystal element 120 when the relative transmittance is 10% is Vth2. At this time, in order to execute the function corresponding to black in the dummy pixel 110b, a voltage (black voltage) such that the effective voltage value held in the liquid crystal element 120 is Vth2 or less is set to the pixel electrode of the dummy pixel 110b. It is only necessary to apply a positive polarity and a negative polarity to 118b.

Further, the liquid crystal element 120 is not limited to a transmissive type, and may be a reflective type. Further, the liquid crystal element 120 is not limited to the normally black mode, and may be a normally white mode in which the liquid crystal element 120 is in a white state when no voltage is applied.
In the normally white mode, the movement of impurities occurs in the black pixels, and the impurities are blocked in the white pixels. Therefore, the corner portion 201 is set to the black pixel, and the peripheral region 200b is similarly set to the white pixel and the black pixel. The alternate arrangement may be used.

<Electronic equipment>
Next, a projector will be described as an example of an electronic apparatus to which the electro-optical device 1 according to the above-described embodiment is applied. FIG. 19 is a plan view showing the configuration of the projector.
As shown in this figure, a projector 2100 is provided with a lamp unit 2102 made of a white light source such as a halogen lamp. The projection light emitted from the lamp unit 2102 is provided with three primary colors of R (red), G (green), and B (blue) by three mirrors 2106 and two dichroic mirrors 2108 disposed therein. And led to the light valves 100R, 100G and 100B corresponding to the respective primary colors. Note that B light has a longer optical path than other R and G colors, and therefore, in order to prevent the loss, B light passes through a relay lens system 2121 including an incident lens 2122, a relay lens 2123, and an exit lens 2124. Led.

In the projector 2100, three sets of electro-optical devices according to the embodiment are provided corresponding to each of the R color, the G color, and the B color. Then, the video data corresponding to each of the R color, G color, and B color is supplied from the upper circuit and converted into the data signal Vid corresponding to each color. The configuration of the light valves 100R, 100G, and 100B is the same as that of the liquid crystal panel 100 described above, and is driven according to data signals corresponding to the R color, G color, and B color.
The lights modulated by the light valves 100R, 100G, and 100B are incident on the dichroic prism 2112 from three directions. In the dichroic prism 2112, the R and B light beams are refracted at 90 degrees, while the G light beam travels straight. Therefore, after the images of the respective colors are combined, a color image is projected onto the screen 2120 by the projection lens 2114.

  Since light corresponding to each of R color, G color, and B color is incident on the light valves 100R, 100G, and 100B by the dichroic mirror 2108, it is not necessary to provide a color filter. In addition, the transmission images of the light valves 100R and 100B are projected after being reflected by the dichroic prism 2112, whereas the transmission image of the light valve 100G is projected as it is, so the horizontal scanning direction by the light valves 100R and 100B is The image is reversed in the horizontal scanning direction by the light valve 100G and displayed in an inverted image.

  In addition to the projector described with reference to FIG. 19, examples of the electronic device include an electronic viewfinder, a rear projection type television, a head mounted display, and the like.

DESCRIPTION OF SYMBOLS 1 ... Electro-optical device, 2 ... Control circuit, 3 ... Memory, 94 ... Black matrix, 100 ... Liquid crystal panel, 101 ... Element substrate, 102 ... Opposite substrate, 105 ... Liquid crystal, 108 ... Common electrode, 110 ... Pixel, 110a ... Display pixel, 110b ... dummy pixel, 116 ... TFT, 118, 118a, 118b ... pixel electrode, 120 ... liquid crystal element, 130 ... scanning line driving circuit, 140 ... data line driving circuit, 200 ... virtual line, 200a ... display area, 200b ... peripheral area, 2100 ... projector

Claims (8)

  1. An element substrate having a display region and a light-shielding region arranged to surround the display region;
    A counter substrate disposed to face the element substrate;
    Liquid crystal sandwiched in a gap between the element substrate and the counter substrate;
    A driving circuit for driving pixels provided corresponding to the display area and pixels provided corresponding to the light shielding area;
    A light shielding portion provided at a position overlapping the light shielding region in plan view,
    The element substrate is
    A first pixel electrode provided corresponding to a pixel in the display area;
    A second pixel electrode provided corresponding to a pixel in the light shielding region;
    Have
    The counter substrate is
    Having a common electrode to which a predetermined voltage is applied;
    The drive circuit is
    A voltage corresponding to a display image is applied to the first pixel electrode,
    A white voltage and a black voltage are alternately applied to a pixel electrode adjacent to the first pixel electrode among the second pixel electrodes, every other pixel as viewed in a direction along the periphery of the display region. An electro-optical device.
  2. The electro-optical device according to claim 1, wherein the white voltage and the black voltage are voltages having a relative transmittance of 10% or less and 90% or more.
  3. The drive circuit is
    Among the second pixel electrodes, a voltage having a higher effective voltage value applied to the liquid crystal among the white voltage and the black voltage is applied to a pixel electrode provided corresponding to a corner portion of the light shielding region. The electro-optical device according to claim 1, wherein the electro-optical device is applied.
  4. The drive circuit is
    The voltage applied to the pixel electrode adjacent to the first pixel electrode among the second pixel electrodes is alternately switched at predetermined time intervals between the white voltage and the black voltage. Or the electro-optical device according to 3.
  5. The drive circuit is
    5. The electro-optical device according to claim 1, wherein the second pixel electrodes applied to the white voltage or the black voltage are aligned radially outward as viewed from the display region.
  6. The electro-optical device according to claim 1, wherein the liquid crystal is a normally black mode.
  7. An element substrate having a display region and a region surrounding the display region;
    A counter substrate disposed to face the element substrate;
    Liquid crystal sandwiched in a gap between the element substrate and the counter substrate;
    A light shielding portion provided at a position overlapping the pixels of the light shielding region in plan view;
    With
    The element substrate is
    A first pixel electrode provided corresponding to a pixel in the display area;
    A second pixel electrode provided corresponding to a pixel in the light shielding region;
    Have
    The counter substrate is
    Having a common electrode to which a predetermined voltage is applied;
    An electro-optical device driving method for driving a plurality of pixels provided corresponding to each of the display region and the light shielding region,
    A voltage corresponding to a display image is applied to the first pixel electrode,
    A white voltage and a black voltage are alternately applied to a pixel electrode adjacent to the first pixel electrode among the second pixel electrodes, every other pixel as viewed in a direction along the periphery of the display region. A method for driving an electro-optical device.
  8. An electronic apparatus comprising the electro-optical device according to claim 1.
JP2011034904A 2011-02-21 2011-02-21 Electro-optical device, drive method for the electro-optical device, and electronic equipment Withdrawn JP2012173489A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014168067A1 (en) * 2013-04-09 2014-10-16 日本精機株式会社 Display device
WO2014188813A1 (en) * 2013-05-23 2014-11-27 ソニー株式会社 Video image signal processing circuit, method for processing video image signal, and display device
CN107966838A (en) * 2017-12-18 2018-04-27 深圳市华星光电技术有限公司 A kind of liquid crystal panel and display device

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014168067A1 (en) * 2013-04-09 2014-10-16 日本精機株式会社 Display device
CN105074803A (en) * 2013-04-09 2015-11-18 日本精机株式会社 Display device
CN105074803B (en) * 2013-04-09 2018-01-02 日本精机株式会社 Display device
WO2014188813A1 (en) * 2013-05-23 2014-11-27 ソニー株式会社 Video image signal processing circuit, method for processing video image signal, and display device
CN107966838A (en) * 2017-12-18 2018-04-27 深圳市华星光电技术有限公司 A kind of liquid crystal panel and display device

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