JP2002207459A - Driving method of liquid crystal display device, driving circuit of liquid crystal display device, liquid crystal display device and electonic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the generation of flicker and also to improve the aperture ratio. SOLUTION: The device has pixels 1 each of which is made of an electrode 3 which is arranged at each of the crossing points of multiple scanning lines 22 and multiple data lines 21, a switching element 2 which controls the voltage applied to every pixel electrode, liquid crystals held at each of the crossing regions of the multiple data lines and multiple scanning lines and an opposing electrode 4 which is oppositely arranged with respect to the pixel electrode. The device is provided with control signals to conduct a.c. driving while data are written into each of the pixels. Moreover, the device has a gamma converting circuit 13 to compensate for the data to be written into each of the pixels so that the optical characteristics of the pixels in a positive polarity segment and the optical characteristics of the pixels in a negative polarity segment become the same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for driving a liquid crystal display device, a driving circuit for a liquid crystal display device, a liquid crystal display device, and electronic equipment.

[0002]

2. Description of the Related Art A liquid crystal display device using liquid crystal as an electro-optical material is widely used as a display device in place of a cathode ray tube (CRT) for a display section of various information processing equipment and a liquid crystal television. In a conventional liquid crystal display device, an element substrate provided with pixel electrodes arranged in a matrix, a switching element such as a TFT (Thin Film Transistor) connected to the pixel electrodes, and a pixel electrode are opposed to each other. It comprises a counter substrate on which a counter electrode (common electrode) is formed, and a liquid crystal filled between the two substrates. In the liquid crystal display device configured as described above, it is general to perform AC driving to extend the life of the liquid crystal.

FIG. 12 shows a relationship between gradation data (input data) N and a voltage (hereinafter, referred to as a liquid crystal driving voltage) V applied to a liquid crystal in performing a gradation display. As shown in the figure, in order to display an image at a specific gradation N0 (for example, a gradation for obtaining the target transmittance T0), a liquid crystal,
It is necessary to apply the voltage V0 between the common electrode and the pixel electrode. However, when the liquid crystal is AC-driven, the characteristics of writing data to the pixel are different between when a positive voltage is applied to the pixel electrode and when a negative voltage is applied, as shown in FIG. different. FIG. 13 is a characteristic diagram showing a relationship between the liquid crystal driving voltage V and the transmittance T of the liquid crystal, and a curve Q1 shows characteristics when a positive voltage is applied to the pixel electrode.
A curve Q2 shows characteristics when a negative voltage is applied to the pixel electrode.

In FIG. 13, when a voltage V0 of the same level as the absolute value is applied, the transmittance of the liquid crystal differs between when a positive voltage is applied to the pixel electrode and when a negative voltage is applied. Are different from T1 and T2. Therefore, as shown in FIG. 14, when the liquid crystal is driven by the alternating signal FR inverted every field (FIG. 14A), even if the target transmittance T0 is to be obtained, a positive voltage is applied to the pixel electrode. Since the transmittance of the liquid crystal is different between when the voltage is applied and when the voltage of the negative polarity is applied, the transmittance of the liquid crystal greatly changes at the AC or the inversion cycle of the signal FR, and the display screen of the liquid crystal display device is displayed. Above, it appears as flicker (FIG. 14B).

Conventionally, when a liquid crystal is driven by a line inversion driving method or a dot inversion driving method, and the change in transmittance on the screen is averaged, or when the liquid crystal is driven by a plane inversion driving method, By increasing the frequency of the alternating signal FR, that is, the field frequency,
Measures have been taken to suppress the occurrence of the flicker described above.

[0006]

FIG. 10 shows an example of the polarity of a potential written to each pixel electrode in the dot inversion driving method and the state of generation of an electric field in an adjacent pixel.
FIG. 1 shows an example of the polarity of a potential written to a pixel electrode in the plane inversion driving method and a state of generation of an electric field in an adjacent pixel. As shown in FIG. 10B, a pixel electrode is formed on the element substrate 50, and for convenience of description, FIG. 10 shows two adjacent pixel electrodes 52A and 52B. Further, a counter substrate 56 on which a common electrode 54 facing the pixel electrodes 52A and 52B is formed with a predetermined gap maintained with respect to the element substrate 50 is provided. As shown in FIG. 10A, in a certain specific field, a voltage having a different polarity from that of an adjacent pixel electrode is applied to each pixel electrode between the common electrode 56 and written to each pixel.

At this time, in the dot inversion driving method shown in FIG. 10B, a vertical electric field is generated between each pixel electrode and the common electrode, and a potential difference between adjacent pixel electrodes is increased. A horizontal electric field is generated between adjacent pixel electrodes. In particular, in a liquid crystal display device having a small pixel size, such as a projection light valve, disclination is likely to occur around a pixel due to an electric field (horizontal electric field) from an adjacent pixel electrode, resulting in a decrease in contrast. In order to avoid this, a black mask 58 is provided at a portion facing the common electrode 54 facing between adjacent pixel electrodes. In this case, it is necessary to form a large black mask region in order to reliably prevent a decrease in contrast due to a lateral electric field generated between pixel electrodes. As a result, there has been a problem that the aperture ratio is reduced and the light use efficiency is also reduced.

When the liquid crystal is driven by the plane inversion driving method, a voltage of the same polarity is applied to all the pixels and the common electrode. For example, in a specific field as shown in FIG. A positive voltage is applied between each pixel electrode and the common electrode, and is written to each pixel. In this plane inversion driving method, there is no potential difference between adjacent pixel electrodes, so that only a vertical electric field is generated. Therefore, unlike the line inversion driving method or the dot inversion driving method, the contrast does not decrease due to the lateral electric field generated between the pixel electrodes, and thus it is not necessary to provide a black mask on the counter substrate side. However, as described above, there is a problem that flicker occurs in the inversion cycle of the AC signal.

The present invention has been made in view of such circumstances, and a method of driving a liquid crystal display device, which suppresses the generation of flicker and improves the aperture ratio, a driving circuit of the liquid crystal display device, and a liquid crystal device. It is an object to provide a display device.

[0010]

In order to achieve the above object, a first aspect of the present invention is a method for driving a plurality of pixels having a liquid crystal sandwiched between intersections of a plurality of data lines and a plurality of scanning lines by AC driving. In the method of driving a liquid crystal display device to display by,
When writing data to each of the plurality of pixels, the control signal for performing the AC drive has the same write characteristic of the pixel in the positive polarity section as the write characteristic of the pixel in the negative polarity section. Data to be written to each pixel is corrected so that

In one aspect of the first invention, the correction of data to be written in each pixel is performed in consideration of a change in a liquid crystal itself constituting the pixel or a change in ambient temperature of the liquid crystal. I do. Further, in another aspect of the first invention, the AC drive is a surface inversion drive.

According to the first aspect, a plurality of pixels including a liquid crystal interposed between intersections of a plurality of data lines and a plurality of scanning lines are displayed by AC driving. In this case, when writing data to each of the plurality of pixels, the control signal for performing the AC drive is an average pixel optical characteristic in a section of positive polarity, and the control signal is in a section of negative polarity. Data written to each pixel is corrected so that the optical characteristics of the average pixel are the same. As a result, the occurrence of flicker on the display screen of the liquid crystal display device can be suppressed, and the aperture ratio can be improved.

The correction of the data to be written in each pixel is performed in consideration of the liquid crystal itself constituting the pixel or a change in the ambient temperature of the liquid crystal. This makes it possible to appropriately suppress flicker in response to changes in the liquid crystal itself or the ambient temperature of the liquid crystal. Further, the AC drive in the liquid crystal display device is performed by a plane inversion drive. As a result, in addition to the effect of suppressing flicker, a horizontal electric field is not generated between adjacent pixels, and therefore, black which is necessary to prevent a decrease in contrast on the display screen due to the generation of the horizontal electric field is required. It is not necessary to provide a mask on the counter substrate facing the element substrate on which the pixel electrodes are formed, and the aperture ratio can be improved.

According to a second aspect of the present invention, there is provided a pixel electrode provided corresponding to each intersection of a plurality of scanning lines and a plurality of data lines, and a switching element for controlling a voltage applied to each pixel electrode. A pixel including a liquid crystal sandwiched between intersections of the plurality of data lines and the plurality of scanning lines, and a counter electrode disposed to face the pixel electrode, and displaying the pixel by AC driving. In the driving circuit of the liquid crystal display device, when data is written to each of the plurality of pixels, the control signal for performing the AC driving is an average pixel optical characteristic in a section of positive polarity, and the control signal is a negative signal. So that the average pixel has the same optical characteristics in the sex section
It is characterized by having data correction means for correcting data to be written to each pixel.

In one embodiment of the second invention, the data correction means corrects data to be written in each pixel in consideration of a change in a liquid crystal itself constituting the pixel or a change in an ambient temperature of the liquid crystal. It is characterized by the following. In another aspect of the second invention, the apparatus further comprises flicker detection means for detecting flicker occurring on the display screen, wherein the data correction means eliminates flicker based on a detection output of the flicker detection means. Thus, the data to be written to the pixel is corrected. Further, in still another aspect of the second invention, the AC drive is a surface inversion drive.

According to the second aspect, a pixel electrode provided corresponding to each intersection of a plurality of scanning lines and a plurality of data lines, and a switching element for controlling a voltage applied to each pixel electrode are provided. In addition, a pixel including a liquid crystal sandwiched in an intersection region of the plurality of data lines and the plurality of scanning lines and a counter electrode disposed to face the pixel electrode is AC-driven and displayed. In this case, when writing data to each of the plurality of pixels, the control signal for performing the AC drive is an average pixel optical characteristic in a section of positive polarity, and the control signal is in a section of negative polarity. The data to be written into each pixel is corrected by the data correction unit so that the optical characteristics of the average pixel become the same. As a result, the occurrence of flicker on the display screen of the liquid crystal display device can be suppressed, and the aperture ratio can be improved.

The correction of the data to be written in each pixel is performed by the data correction means in consideration of a change in the liquid crystal itself constituting the pixel or a change in the ambient temperature of the liquid crystal. This makes it possible to appropriately suppress flicker in response to a change in the liquid crystal itself or the ambient temperature of the liquid crystal. Further, the data correction means corrects data to be written to the pixel based on the detection output of the flicker detection means so as to eliminate flicker. This makes it possible to appropriately suppress flicker occurring on the display screen of the liquid crystal display device according to the state of occurrence of flicker.
Further, the AC drive in the liquid crystal display device is performed by a plane inversion drive. As a result, in addition to the effect of suppressing flicker, a horizontal electric field is not generated between adjacent pixels, and therefore, black which is necessary to prevent a decrease in contrast on the display screen due to the generation of the horizontal electric field is required. It is not necessary to provide a mask on the counter substrate facing the element substrate on which the pixel electrodes are formed, and the aperture ratio can be improved.

According to a third aspect of the present invention, there is provided a pixel electrode provided corresponding to each intersection of a plurality of scanning lines and a plurality of data lines, and a switching element for controlling a voltage applied to each pixel electrode. A liquid crystal sandwiched in an intersection region between the plurality of data lines and the plurality of scanning lines, a pixel including a counter electrode disposed to face the pixel electrode, and a scanning line driving circuit driving the scanning line; A data line driving circuit for driving the data line, and control means for controlling the scanning line driving circuit and the data line driving circuit, wherein the pixel is AC-driven by the scanning line driving circuit and the data line driving circuit. In the liquid crystal display device, the control means, when writing data to each of the plurality of pixels, the control signal for performing the AC drive is an average pixel optical characteristics in a section of positive polarity, Said Wherein the control signal has a data correction means and the optical properties of the average pixel in the negative polarity period to correct the data to be written to each pixel to be the same.

In one embodiment of the third invention, the data correction means corrects the data to be written in each pixel in consideration of the change in the liquid crystal itself constituting the pixel or the ambient temperature of the liquid crystal. It is characterized by the following. In another aspect of the third invention, the apparatus further comprises flicker detection means for detecting flicker occurring on the display screen, wherein the data correction means eliminates flicker based on a detection output of the flicker detection means. It is characterized in that data to be written to the pixel is corrected. In still another aspect of the third invention, the control means drives the pixel by the surface inversion driving by the scanning line driving circuit and the data line driving circuit.

According to the third aspect of the present invention, there is provided a pixel electrode provided at each intersection of a plurality of scanning lines and a plurality of data lines, and a switching element for controlling a voltage applied to each pixel electrode. A scanning line driving circuit in which a pixel including a liquid crystal sandwiched in an intersection region of the plurality of data lines and the plurality of scanning lines and a counter electrode disposed to face the pixel electrode is controlled by control means; The data is driven and displayed by the data line driving circuit. In this case, when writing data to each of the plurality of pixels by the data correction unit of the control unit, the control signal for performing the AC driving may include an average pixel optical characteristic in a positive polarity section and The data to be written into each pixel is corrected so that the control signal has the same optical characteristic as the average pixel in the negative polarity section. As a result, the occurrence of flicker on the display screen of the liquid crystal display device can be suppressed, and the aperture ratio can be improved.

The correction of the data to be written into each pixel is performed by the data correction means in consideration of the change in the liquid crystal itself constituting the pixel or the ambient temperature of the liquid crystal. This makes it possible to appropriately suppress flicker in response to a change in the liquid crystal itself or the ambient temperature of the liquid crystal. Further, the data correction means corrects data to be written to the pixel based on the detection output of the flicker detection means so as to eliminate flicker. This makes it possible to appropriately suppress flicker occurring on the display screen of the liquid crystal display device according to the state of occurrence of flicker.

Further, the control means drives the pixel by a surface inversion by the scanning line driving circuit and the data line driving circuit. As a result, in addition to the effect of suppressing flicker, a horizontal electric field is not generated between adjacent pixels, and therefore, black which is necessary to prevent a decrease in contrast on the display screen due to the generation of the horizontal electric field is required. It is not necessary to provide a mask on the counter substrate facing the element substrate on which the pixel electrodes are formed, and the aperture ratio can be improved.

Further, in the electronic device according to the fourth aspect of the present invention, since the above-mentioned liquid crystal display device is provided, the occurrence of flicker on the display screen of the liquid crystal display device can be suppressed. Further, since the electronic apparatus according to the fourth aspect includes the liquid crystal display device, it is possible to appropriately suppress flicker in response to a change in the liquid crystal itself or an ambient temperature of the liquid crystal. Further, since the electronic apparatus according to the fourth aspect includes the liquid crystal display device, flicker generated on the display screen of the liquid crystal display device can be appropriately suppressed according to the state of flicker generation.

Further, since the electronic apparatus according to the fourth aspect of the present invention includes the above-described liquid crystal display device, the pixel is driven by the scanning line driving circuit and the data line driving circuit for surface inversion, so that the flicker can be suppressed. Therefore, a horizontal electric field is not generated between adjacent pixels, and therefore, a black mask, which is necessary to prevent a decrease in contrast in a display screen due to the generation of a horizontal electric field, is used as an element substrate on which pixel electrodes are formed. Therefore, it is not necessary to provide the counter substrate on the counter substrate, and the aperture ratio can be improved.

[0025]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, in the liquid crystal display device according to this embodiment, the element substrate on which the pixel electrode is formed and the opposing substrate on which the opposing electrode (common electrode) opposing the pixel electrode are formed are kept at a constant gap from each other. A liquid crystal, which is an electro-optical material, is sealed in the gap and sandwiched. FIG. 1 shows an electrical configuration of the liquid crystal display device according to the present embodiment. In FIG. 1, the liquid crystal display device according to the present embodiment includes a scanning line driving circuit 10, a data line driving circuit 11, a pixel matrix 12 in which pixels are formed in a matrix, a gamma conversion circuit 13, and a gamma conversion circuit 13. D / A conversion circuit 14 for D / A converting the output of circuit 13
A polarity inversion circuit 15 for inverting the polarity of the output signal of the D / A conversion circuit 14 for each field, and a data buffer 16
And a sample and hold transistor 20 for distributing a video signal to each data line 21, and a flicker detection circuit 30.

Data line 21 in pixel matrix 12
The pixel 1 formed in the intersection region between the scanning line 22 and the pixel electrode 3 includes a pixel electrode 3 formed on the element substrate corresponding to each intersection of the plurality of scanning lines 22 and the plurality of data lines 21, , A switching element 2 for controlling a voltage applied to the pixel, a liquid crystal interposed between intersections of a plurality of scanning lines 22 and a plurality of data lines 21, and a counter electrode disposed on a counter substrate facing the pixel electrode 3. And 4. The common potential LCCOM is supplied to the counter electrode 4. Scan line drive circuit 10
, A scan start pulse DY and a scan shift clock CLY are input, and a scan start pulse is transferred at the output timing of the scan shift clock CLY.
2 are performed.

The data line drive circuit 11 receives the latch pulse LP and the shift clock CLX, and transfers the latch pulse LP by the shift clock CLX.
An image signal is held in the sample-and-hold transistor 20, and an image signal is supplied to each data line 21. The gamma conversion circuit 13 AC-drives each pixel 1 (plane inversion driving in the present embodiment), and writes AC data signal (image signal). Is such that the writing characteristic of the pixel 1 in the section of the positive polarity and the writing characteristic of the pixel in the section of the alternating signal FR in the negative polarity are the same.
It has a function of correcting data to be written to each pixel.
That is, the correction is performed when the input data is converted into the drive signal so that the pixel has the same transmittance when the display data is written with the positive polarity and the negative polarity.

The gamma conversion circuit 13 includes input data (image data) D0 to Dn composed of a plurality of bits, an AC signal FR output from a control unit (not shown), the liquid crystal itself constituting the pixel 1, or A detection output of a temperature sensor (not shown) for detecting the ambient temperature of the liquid crystal and a detection output of the flicker detection circuit 30 are input. Gamma conversion circuit 1
Reference numeral 3 determines a liquid crystal drive signal to be output from the image data based on the detection output of the temperature sensor and the detection output of the flicker detection circuit. At this time, as described above, the liquid crystal drive signal is obtained using a data conversion table for positive polarity in a section where the AC conversion signal FR is positive and for a negative polarity in a section where the AC conversion signal FR is negative. Has become.

The gamma conversion circuit 13 corresponds to the data correction means of the present invention.

The polarity inversion circuit 15 is a drive signal input from the gamma conversion circuit 13 through the D / A conversion circuit 14 based on the input AC signal FR (FIG. 2B), that is, an analog image. Signal VIDEO '(FIG. 2 (C))
Signal VIDEO (FIG. 2)
(A)), and outputs the data to the sample-and-hold transistor 20 via the data buffer 16.

Next, the flicker detection circuit 30 will be described with reference to FIGS. The flicker detection circuit 30 includes a light source 30A and a flicker detector 30B. For example, when the liquid crystal display device is a transmissive type, as shown in FIG. 3, a detection area 50B for detecting flicker is provided in the liquid crystal display device 50 in addition to a display area 50A for displaying an image. And the pixels in the detection area are driven under the same conditions, light is emitted from the light source 30A to the detection area, and flicker is detected by the flicker detector 30B that receives the transmitted light. When the transmitted light of the detection area 50B is, for example, each pixel of the liquid crystal display device 50 being AC-driven at 30 Hz, the flicker detector 30B has a brightness peak cycle of 30 Hz, which is an inversion cycle of the AC signal FR. It is determined whether or not flicker has occurred, based on whether or not it changes.

The detection of the flicker is performed for all gradations, for example, by setting the pixels in the detection area 50B to a constant transmittance (gradation) at predetermined intervals or during a calibration period such as immediately after the start-up. , Gamma conversion circuit 1
The conversion data in the conversion table for positive polarity and the conversion table for negative polarity in 3 are set so as to eliminate flicker. The conversion data in the conversion table for positive polarity in the gamma conversion circuit 13 and the conversion data in the conversion table for negative polarity have an appropriate value that does not cause flicker based on a change in temperature of the liquid crystal itself constituting the pixel or around the liquid crystal. The setting is made by the gamma conversion circuit 13 to be changed based on the detection output of the temperature sensor.

Here, a method of determining the conversion data when changing the conversion data will be described with reference to FIGS. As shown in FIG. 8A, the display area of the liquid crystal display device is divided into a plurality of areas A11 to A33 (in the present embodiment, it is divided into nine for convenience of explanation), and pixels representing each area are divided. For the points P11 to P33, a write voltage corresponding to each gradation, that is, a liquid crystal drive voltage is defined, and the liquid crystal drive voltages of the pixels other than the pixel point representing each area are determined by interpolation for the pixel points P11 to P33.

For example, as shown in FIG. 8B, the liquid crystal drive voltage Vx at a certain gray level at a point Px on a straight line connecting the pixel point P11 in the area A11 and the pixel point P12 in the area A12 is the gray scale. The liquid crystal drive voltage at pixel point P11 at V is
, The distance from the pixel point P11 to the point Px is x1, and the distance from the pixel point P12 to the point Px
Vx = (V × 1 + V ′ × 2) / (x1 + x2) (1)

For the pixels that deviate from the straight line connecting the representative pixel points, the liquid crystal driving voltage, that is, the conversion data is determined by performing, for example, a three-stage linear interpolation operation as shown in FIG. That is, in FIG. 9, the pixel point to be determined is Px, and the area A11,
The representative pixel points at A12, A21, and A22 are P11, P12, P21, and P22, respectively. Pixel point P11
And the pixel point P12 by a straight line, and the pixel point P21 and the pixel point P22 by a straight line, pass through the pixel point Px, and pass through the pixel point P11 and the pixel point P1.
2, a pixel point P21 and a pixel point P2
The points of intersection with the straight line connecting 2 are Px1 and Px2, respectively. In addition, these representative pixel points P11, P12, P2
1, the liquid crystal driving voltage at a certain gradation of P22 is V11, V1
2, V21 and V22.

Here, regarding the point Px1, the pixel point P11
And the liquid crystal drive voltage V defined for the pixel point P12
11, the liquid crystal drive voltage Vx1 is obtained from V12 by the above-described linear interpolation operation, and then the liquid crystal drive voltage V2 defined for the pixel point P21 and the pixel point P22 for the point Px2.
1. A liquid crystal drive voltage Vx2 is obtained from V22 by a linear interpolation operation. Finally, the liquid crystal drive voltage Vx is obtained by the above-described linear interpolation calculation for the pixel point Px on the straight line connecting the points Px1 and Px2.

When the liquid crystal display device is of a reflection type (in the case of a liquid crystal projector or the like), as shown in FIG. 4, in the liquid crystal display device 60, light emitted from a light source 30A is transmitted to a specific pixel of a display area 60A. And the reflected light is received by the flicker detector 30B to detect flicker. The method of detecting flicker is the same as that of the transmission type liquid crystal display device 50 shown in FIG. In the flicker detection circuit 30 shown in FIG.
Since the reflected light from 0A does not enter the projection lens side, it does not affect the display. The flicker detection circuit 30 shown in FIG. 4 can actually measure the state of occurrence of flicker in the display area 60A. The flicker detection circuit 30 corresponds to flicker detection means of the present invention. Further, the gamma conversion means 13, the D / A conversion circuit and the polarity inversion circuit 15 constitute a part of the control means of the present invention.

In the above configuration, for example, if the liquid crystal display device is of a transmission type, the conversion data in the conversion table for the positive polarity in the gamma conversion circuit 13 and the conversion data in the conversion table for the negative polarity are output to the detection output of the flicker detection circuit 30 at startup. On the basis of this, initial settings are made so that flicker does not occur over all gradations. Further, at this time, based on the detection output of the liquid crystal itself or a temperature sensor that detects the temperature around the liquid crystal, the conversion table for the positive polarity that is initially set,
The conversion data in the conversion table for negative polarity is set so as to be corrected to an appropriate value corresponding to the temperature. The initial setting of the conversion data in each table based on the detection output of the flicker detection circuit 30 and the update of the conversion data in each table based on the detection output of the temperature sensor are appropriately performed.

Next, as described above, the gamma conversion circuit 13
In the state where the conversion data for the positive polarity conversion table and the conversion data for the negative polarity conversion table are set, the gamma conversion circuit 13 outputs the image data D0 composed of a plurality of bits.
To Dn, a conversion table for positive polarity in which a liquid crystal driving voltage corresponding to the gradation Ni (corresponding to the transmittance T0 of the pixel) indicated by the image data D0 to Dn is set, and a conversion table for negative polarity And ask from. Here, FIG. 5 is a characteristic diagram showing the relationship between the gradation data and the liquid crystal driving voltage, and FIG. 6 is a characteristic diagram showing the relationship between the liquid crystal driving voltage and the transmittance of the liquid crystal. In FIG. 5, a curve Q10 indicates conversion data set in the conversion table for positive polarity, and a curve Q11 indicates conversion data set in the conversion table for negative polarity, as analog characteristics for convenience of explanation. It is a thing. Each table is set as digital data.

As shown in FIG. 5, in order to obtain the target transmittance T0 corresponding to the gradation Ni indicated by the image data D0 to Dn, the liquid crystal drive voltage V1 is applied to the pixel during the period when the AC signal FR is positive.
It is necessary to write the liquid crystal drive voltage V2 to the pixel during the period when the AC conversion signal FR is negative. By setting the liquid crystal drive voltage to be written to the pixel in this manner, as shown in FIG. 6, a period in which the AC signal FR has a positive polarity and a period in which the AC signal FR has a negative polarity have respective periods. The average transmittance of the pixels, that is, the transmittance of the liquid crystal is maintained at the target transmittance T0. As a result, as shown in FIG.
In the case where the liquid crystal is driven by the alternating signal FR inverted for each field (FIG. 7A), N
When i is set over a plurality of fields, the target transmittance T0 is substantially maintained in each of these fields, and the occurrence of flicker is suppressed.

As described above, according to the liquid crystal display device of the embodiment of the present invention, the pixel electrodes provided corresponding to the intersections of the plurality of scanning lines and the plurality of data lines, A switching element for controlling a voltage to be applied, a liquid crystal interposed between intersections of the plurality of data lines and the plurality of scanning lines, and a pixel including a counter electrode disposed to face the pixel electrode; A scanning line driving circuit for driving a line; a data line driving circuit for driving the data line; and control means for controlling the scanning line driving circuit and the data line driving circuit. And a liquid crystal display device that performs AC driving and display by a data line driving circuit, wherein the control unit is configured such that when writing data to each of the plurality of pixels, the control signal for performing the AC driving is in a positive polarity section. Oak The liquid crystal display device includes a data correction unit that corrects data written to each pixel so that the average optical characteristic of the pixel and the average optical characteristic of the pixel in the section where the control signal is negative are the same. Can suppress the occurrence of flicker on the display screen and improve the aperture ratio.

Further, according to the liquid crystal display device according to the embodiment of the present invention, the data correction means corrects the data to be written in each pixel by adjusting the liquid crystal itself constituting the pixel or the ambient temperature of the liquid crystal. Therefore, flicker can be appropriately suppressed in accordance with a change in the liquid crystal itself or an ambient temperature of the liquid crystal. Further, according to the liquid crystal display device according to the embodiment of the present invention, the data correction unit corrects data to be written to the pixel so as to eliminate flicker based on the detection output of the flicker detection unit.
The flicker generated on the display screen of the liquid crystal display device is
It is possible to appropriately suppress the occurrence of flickers.

Further, according to the liquid crystal display device according to the embodiment of the present invention, the control means drives the pixels with the scanning line driving circuit and the data line driving circuit, so that the effect of suppressing flicker is reduced. In addition, no horizontal electric field is generated between adjacent pixels, and therefore, the pixel electrode is formed with a black mask, which was necessary to prevent a decrease in contrast on the display screen due to the generation of the horizontal electric field. It is not necessary to provide on the opposing substrate facing the element substrate,
The aperture ratio can be improved.

<Overall Structure of Liquid Crystal Device> Next, with respect to the structure of the liquid crystal display device according to the above-described embodiment and application,
This will be described with reference to FIGS. Here, FIG.
5 is a plan view showing the configuration of the liquid crystal display device 100,
FIG. 16 is a sectional view taken along line AA ′ in FIG.
As shown in these figures, the liquid crystal display device 100
An element substrate 101 on which the pixel electrode 3 and the like are formed and an opposing substrate 102 on which the opposing electrode 4 and the like are formed are bonded to each other by a sealing material 104 with a constant gap therebetween. Liquid crystal 10
5 is sandwiched. In practice,
The sealing material 104 has a cutout portion, and after the liquid crystal 105 is sealed through the cutout portion, the liquid crystal 105 is sealed with a sealing material.
They are omitted in these figures.

The counter substrate 102 is a transparent substrate made of glass or the like. Further, in the above description, the element substrate 101 is described as being made of a transparent substrate. However, in the case of a reflective liquid crystal display device, a semiconductor substrate can be used.
In this case, since the semiconductor substrate is opaque, the pixel electrode 3 is formed of a reflective metal such as aluminum. On the element substrate 101, a light-shielding film 106 is provided inside the sealant 104 and outside the display area 101a. The scanning line driving circuit 10 is formed in a region 130a of the region where the light shielding film 106 is formed.
The data line drive circuit 11 is formed in the region 140a.

That is, the light-shielding film 106 prevents light from entering a drive circuit formed in this region. The light-shielding film 106 is configured to be applied with the common electrode 4 and the common electrode voltage VLCCOM. Also,
In the element substrate 101, a plurality of connection terminals are formed in an area 107 outside the area 140a where the data line drive circuit 11 is formed and separated by the sealant 104,
The configuration is such that a control signal or power supply from the outside is input.

On the other hand, the opposing electrode 4 of the opposing substrate 102 is connected to the light-shielding film 106 and the connection terminals of the element substrate 101 by a conductive material (not shown) provided in at least one of the four corners of the substrate bonding portion. Electrical continuity is achieved. That is, the common electrode voltage VLCC
The OM is configured to be applied to the light-shielding film 106 via a connection terminal provided on the element substrate 101 and further to the counter electrode 4 via a conductive material. Besides,
According to the application of the liquid crystal display device 100, for example, in the case of a direct-view type, first, a color filter arranged in a stripe shape, a mosaic shape, a triangle shape, or the like is provided on the counter substrate 102. For example, a light-shielding film (black matrix) made of a metal material, a resin, or the like is provided.

In the case of color light modulation, for example, when used as a light valve of a projector described later, no color filter is formed. In the case of a direct-view type, a light for irradiating light from the counter substrate 102 side or the element substrate side to the liquid crystal display device 100 is provided as necessary. In addition, an alignment film (not shown) rubbed in a predetermined direction or the like is provided on each of the electrode forming surfaces of the element substrate 101 and the counter substrate 102 to regulate the alignment direction of the liquid crystal molecules in the state where no voltage is applied. On the other hand, on the side of the counter substrate 101, a polarizer (not shown) corresponding to the orientation direction is provided. However, when a polymer-dispersed liquid crystal in which fine particles are dispersed in a polymer is used as the liquid crystal 105, the above-described alignment film and polarizer are not required, and the light use efficiency is increased. This is advantageous in terms of low power consumption and the like.

<Electronic Equipment> Next, some examples in which the above-described liquid crystal device is used in specific electronic equipment will be described. <Projector> First, a projector using the liquid crystal display device according to the embodiment as a light valve will be described. FIG. 17 is a plan view showing the configuration of this projector. As shown in this figure, the projector 1100
Inside, a polarized illumination device 1110 is arranged along the system optical axis PL.

In the polarized light illuminating device 1110, the light emitted from the lamp 1112 is converted into a substantially parallel light beam by the reflection by the reflector 1114, and enters the first integrator lens 1120. Thereby, the lamp 1112
Is split into a plurality of intermediate light beams. The split intermediate light beam is converted by the polarization conversion element 1130 having the second integrator lens on the light incident side into one type of polarized light beam (s-polarized light beam) whose polarization direction is almost uniform, and the polarized light illumination device 1110. From the light source.

Now, the s-polarized light beam emitted from the polarized light illuminating device 1110 is reflected by the s-polarized light beam reflecting surface 1141 of the polarizing beam splitter 1140. Of this reflected light beam, the light beam of blue light (B) is reflected by the blue light reflecting layer of the dichroic mirror 1151, and is modulated by the reflective liquid crystal display device 100B. Further, among the light beams transmitted through the blue light reflecting layer of the dichroic mirror 1151, the light beam of red light (R) is
The light is reflected by the red light reflection layer 52 and is modulated by the reflection type liquid crystal display device 100R.

On the other hand, among the light beams transmitted through the blue light reflecting layer of the dichroic mirror 1151, the light beam of green light (G) transmits through the red light reflecting layer of the dichroic mirror 1152, and becomes a reflection type liquid crystal display device 100G. Modulated by Thus, the liquid crystal display devices 100R, 100R
The red, green, and blue lights, each of which is color-modulated by G and 100B, are dichroic mirrors 1152 and 115, respectively.
51, after being sequentially synthesized by the polarizing beam splitter 1140, the screen 1 is projected by the projection optical system 1160.
170 is projected. The liquid crystal display device 1
Since light beams corresponding to the primary colors of R, G, and B are incident on 00R, 100B, and 100G by dichroic mirrors 1151, 1152, a color filter is not necessary. In the present embodiment, a reflection type liquid crystal display device is used, but a projector using a transmission type liquid crystal display device may be used.

<Mobile Computer> Next, an example in which the liquid crystal display device is applied to a mobile personal computer will be described. FIG. 18 is a perspective view showing the configuration of this personal computer. In the figure, a computer 1200 includes a main body 1204 having a keyboard 1202 and a display unit 1206. The display unit 1206 is configured by adding a front light to the front surface of the liquid crystal display device 100 described above. In this configuration, since the liquid crystal display device 100 is used as a reflection direct-view type, it is preferable that the pixel electrode 3 has a configuration in which unevenness is formed so that reflected light is scattered in various directions.

<Cellular Phone> An example in which the above-described electro-optical device is applied to a cellular phone will be described. FIG.
1 is a perspective view showing the configuration of the mobile phone. In the figure, a mobile phone 1300 has a plurality of operation buttons 1302.
In addition, the liquid crystal display device 100 is provided together with the earpiece 1304 and the mouthpiece 1306. This liquid crystal display device 100 is also provided with a front light on its front face, if necessary. Also in this configuration, the liquid crystal display device 10
Since 0 is used as a reflection direct-view type, a configuration in which unevenness is formed on the pixel electrode 3 is desirable.

FIGS. 18 and 19 show examples of electronic equipment.
In addition to those described with reference to the above, a liquid crystal television, a viewfinder type, a video tape recorder of a monitor direct-view type, a car navigation device, a pager, an electronic organizer, a calculator, a word processor, a workstation, a videophone, a PO
An S terminal, a device equipped with a touch panel, and the like are included. Needless to say, the liquid crystal display device according to the embodiment or the application form can be applied to these various electronic devices.

[0056]

According to the first aspect of the present invention, a plurality of pixels including liquid crystals sandwiched between intersections of a plurality of data lines and a plurality of scanning lines are displayed by AC driving. In this case, when writing data to each of the plurality of pixels,
The control signal for performing the AC drive is applied to each pixel such that the average optical characteristic of the pixel in the section of the positive polarity and the control signal are the same as the average optical characteristic of the pixel in the section of the negative polarity. The data to be written is corrected. As a result, the occurrence of flicker on the display screen of the liquid crystal display device can be suppressed, and the aperture ratio can be improved.

The correction of the data to be written into each pixel is performed in consideration of the change in the liquid crystal itself constituting the pixel or the ambient temperature of the liquid crystal. This makes it possible to appropriately suppress flicker in response to changes in the liquid crystal itself or the ambient temperature of the liquid crystal. Further, the AC drive in the liquid crystal display device is performed by a plane inversion drive. As a result, in addition to the effect of suppressing flicker, a horizontal electric field is not generated between adjacent pixels, and therefore, black which is necessary to prevent a decrease in contrast on the display screen due to the generation of the horizontal electric field is required. It is not necessary to provide a mask on the counter substrate facing the element substrate on which the pixel electrodes are formed, and the aperture ratio can be improved.

According to the second aspect, a pixel electrode provided corresponding to each intersection of a plurality of scanning lines and a plurality of data lines, and a switching element for controlling a voltage applied to each pixel electrode are provided. In addition, a pixel including a liquid crystal sandwiched in an intersection region of the plurality of data lines and the plurality of scanning lines and a counter electrode disposed to face the pixel electrode is AC-driven and displayed. In this case, when writing data to each of the plurality of pixels, the control signal for performing the AC drive is an average pixel optical characteristic in a section of positive polarity, and the control signal is in a section of negative polarity. The data to be written into each pixel is corrected by the data correction unit so that the optical characteristics of the average pixel become the same. As a result, the occurrence of flicker on the display screen of the liquid crystal display device can be suppressed, and the aperture ratio can be improved.

The correction of the data to be written in each pixel is performed by the data correction means in consideration of the change in the liquid crystal itself forming the pixel or the ambient temperature of the liquid crystal. This makes it possible to appropriately suppress flicker in response to a change in the liquid crystal itself or the ambient temperature of the liquid crystal. Further, the data correction means corrects data to be written to the pixel based on the detection output of the flicker detection means so as to eliminate flicker. This makes it possible to appropriately suppress flicker occurring on the display screen of the liquid crystal display device according to the state of occurrence of flicker.

Further, the AC drive in the liquid crystal display device is performed by a plane inversion drive. As a result, in addition to the effect of suppressing flicker, a horizontal electric field is not generated between adjacent pixels, and therefore, black which is necessary to prevent a decrease in contrast on the display screen due to the generation of the horizontal electric field is required. It is not necessary to provide a mask on the counter substrate facing the element substrate on which the pixel electrodes are formed, and the aperture ratio can be improved.

According to the third aspect, a pixel electrode provided corresponding to each intersection of a plurality of scanning lines and a plurality of data lines, and a switching element for controlling a voltage applied to each pixel electrode are provided. A scanning line driving circuit in which a pixel including a liquid crystal sandwiched in an intersection region of the plurality of data lines and the plurality of scanning lines and a counter electrode disposed to face the pixel electrode is controlled by control means; The data is driven and displayed by the data line driving circuit. In this case, when writing data to each of the plurality of pixels by the data correction unit of the control unit, the control signal for performing the AC driving may include an average pixel optical characteristic in a positive polarity section and The data to be written into each pixel is corrected so that the control signal has the same optical characteristic as the average pixel in the negative polarity section. As a result, the occurrence of flicker on the display screen of the liquid crystal display device can be suppressed, and the aperture ratio can be improved.

The correction of the data to be written in each pixel is performed by the data correction means in consideration of a change in the liquid crystal itself constituting the pixel or a change in the ambient temperature of the liquid crystal. This makes it possible to appropriately suppress flicker in response to changes in the liquid crystal itself or the ambient temperature of the liquid crystal. Further, the data correction means corrects data to be written to the pixel based on the detection output of the flicker detection means so as to eliminate flicker. This makes it possible to appropriately suppress flicker occurring on the display screen of the liquid crystal display device according to the state of occurrence of flicker.

Further, the control means drives the pixel by the scanning line driving circuit and the data line driving circuit. As a result, in addition to the effect of suppressing flicker, a horizontal electric field is not generated between adjacent pixels, and therefore, black which is necessary to prevent a decrease in contrast on the display screen due to the generation of the horizontal electric field is required. It is not necessary to provide a mask on the counter substrate facing the element substrate on which the pixel electrodes are formed, and the aperture ratio can be improved.

Since the electronic apparatus according to the fourth aspect includes the liquid crystal display device, it is possible to suppress the occurrence of flicker on the display screen of the liquid crystal display device. Further, since the electronic apparatus according to the fourth aspect includes the liquid crystal display device, it is possible to appropriately suppress flicker in response to a change in the liquid crystal itself or an ambient temperature of the liquid crystal. Further, since the electronic apparatus according to the fourth aspect includes the liquid crystal display device, flicker generated on the display screen of the liquid crystal display device can be appropriately suppressed according to the state of flicker generation.

Further, since the electronic apparatus according to the fourth aspect of the present invention includes the liquid crystal display device, in addition to the effect of suppressing flicker, the pixel is driven by the scanning line driving circuit and the data line driving circuit for surface inversion driving. Therefore, a horizontal electric field is not generated between adjacent pixels, and therefore, a black mask, which is necessary to prevent a decrease in contrast in a display screen due to the generation of a horizontal electric field, is used as an element substrate on which pixel electrodes are formed. Therefore, it is not necessary to provide the counter substrate on the counter substrate, and the aperture ratio can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an electrical configuration of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a timing chart showing an operation state of the liquid crystal display device according to the embodiment of the present invention shown in FIG.

FIG. 3 is an explanatory diagram showing an example of a configuration of a flicker detection circuit in the liquid crystal display device according to the embodiment of the present invention shown in FIG.

FIG. 4 is an explanatory diagram showing another example of the configuration of the flicker detection circuit in the liquid crystal display device according to the embodiment of the present invention shown in FIG.

FIG. 5 is a characteristic diagram showing writing characteristics of pixels in a gamma conversion circuit in the liquid crystal display device according to the embodiment of the present invention shown in FIG.

FIG. 6 is a characteristic diagram showing a relationship between a liquid crystal driving voltage and a liquid crystal transmittance in the liquid crystal display device according to the embodiment of the present invention shown in FIG.

FIG. 7 is an explanatory diagram showing an effect of the liquid crystal display device according to the embodiment of the present invention shown in FIG.

FIG. 8 is an explanatory diagram showing an example of a method of determining conversion data for defining a writing characteristic of a pixel in the gamma conversion circuit in the liquid crystal display device according to the embodiment of the present invention shown in FIG.

FIG. 9 is an explanatory diagram showing another example of a method of determining conversion data for defining a writing characteristic of a pixel in the gamma conversion circuit in the liquid crystal display device according to the embodiment of the present invention shown in FIG.

FIG. 10 is an explanatory diagram showing an example of a polarity of a potential written to each pixel electrode in a dot inversion driving method and a state of generation of an electric field in an adjacent pixel.

FIG. 11 is an explanatory diagram showing an example of the polarity of a potential written to each pixel electrode in the plane inversion driving method, and a state of generation of an electric field in an adjacent pixel.

FIG. 12 is a characteristic diagram illustrating a relationship between gradation data and a liquid crystal drive voltage in a liquid crystal display device.

FIG. 13 is a characteristic diagram showing a relationship between a liquid crystal driving voltage and a transmittance of a liquid crystal in a liquid crystal display device.

FIG. 14 is an explanatory diagram showing a state in which flicker occurs in a conventional liquid crystal display device.

FIG. 15 is a plan view showing the structure of the electro-optical device according to the embodiment of the invention.

FIG. 16 is a sectional view showing the structure of the electro-optical device according to the embodiment of the invention.

FIG. 17 is a cross-sectional view illustrating a configuration of a projector as an example of an electronic apparatus to which the electro-optical device according to the embodiment of the invention is applied.

FIG. 18 is a perspective view illustrating a configuration of a personal computer as an example of an electronic apparatus to which the electro-optical device according to an embodiment of the present invention has been applied.

FIG. 19 is a perspective view showing a configuration of a mobile phone as an example of an electronic apparatus to which the electro-optical device according to the embodiment of the present invention is applied.

[Explanation of symbols]

 Reference Signs List 1 pixel 2 switching element 3 pixel electrode 4 counter electrode 10 scanning line driving circuit 11 data line driving circuit 12 pixel matrix 13 gamma conversion circuit 14 D / A conversion circuit 15 polarity inversion circuit 21 data line 22 scanning line 100 liquid crystal display device 101 element Substrate 101a Display area 102 Opposite substrate 105 Liquid crystal

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) G09G 3/20 642 G09G 3/20 642C F term (Reference) 2H093 NA31 NA51 NC23 NC34 NC47 NC57 NC59 ND02 ND06 ND10 NG02 5C006 AC28 AF44 AF46 BB16 BC06 EC05 EC11 EC13 FA18 FA23 FA56 5C080 AA10 BB05 DD06 DD30 EE29 EE32 FF07 JJ02 JJ04 JJ05 JJ06 KK02 KK07 KK43

Claims (12)

[Claims] 1. A method of driving a liquid crystal display device, which displays a plurality of pixels including liquid crystal interposed between intersections of a plurality of data lines and a plurality of scanning lines by AC driving, wherein each of the plurality of pixels includes: When writing data, the control signal for performing the AC drive has the same average optical characteristics of pixels in the positive polarity section as the average optical properties of the pixels in the negative polarity section. A method of driving a liquid crystal display device, comprising correcting data to be written to each pixel. 2. The correction of data to be written to each pixel is as follows:
The method according to claim 1, wherein the driving is performed in consideration of a change in a liquid crystal itself forming the pixel or an ambient temperature of the liquid crystal. 3. The driving method for a liquid crystal display device according to claim 1, wherein the AC driving is a surface inversion driving. 4. A pixel electrode disposed corresponding to each intersection of a plurality of scanning lines and a plurality of data lines, a switching element for controlling a voltage applied to each pixel electrode, and the plurality of data lines. And a driving circuit for a liquid crystal display device having a pixel including a liquid crystal interposed between intersection regions of a plurality of scanning lines and a counter electrode disposed to face the pixel electrode, and displaying the pixel by AC driving and displaying the pixel. In writing data into each of the plurality of pixels, the control signal for performing the AC drive is an average pixel optical characteristic in a section of positive polarity, and the control signal is an average of an optical characteristic in a section of negative polarity. A driving circuit for a liquid crystal display device, comprising: a data correcting means for correcting data written to each pixel so that optical characteristics of the pixels are the same. 5. The data correction means according to claim 4, wherein the correction of the data to be written to each pixel is performed in consideration of a change in a liquid crystal itself constituting the pixel or a change in ambient temperature of the liquid crystal. 3. A driving circuit for a liquid crystal display device according to claim 1. 6. A flicker detecting unit for detecting flicker occurring on a display screen, wherein the data correcting unit corrects data to be written to a pixel based on a detection output of the flicker detecting unit so as to eliminate flicker. The driving circuit of a liquid crystal display device according to claim 4, wherein 7. The driving circuit according to claim 4, wherein the AC driving is a surface inversion driving. 8. A pixel electrode provided corresponding to each intersection of a plurality of scanning lines and a plurality of data lines, a switching element for controlling a voltage applied to each pixel electrode, and a plurality of data lines. And a pixel including a liquid crystal sandwiched in an intersection region of a plurality of scanning lines, a counter electrode disposed to face the pixel electrode, a scanning line driving circuit driving the scanning line, and driving the data line. A liquid crystal display device having a data line drive circuit for controlling the scan line drive circuit and the data line drive circuit, and displaying the pixels by AC driving with the scan line drive circuit and the data line drive circuit In the control unit, when writing data to each of the plurality of pixels, the control signal for performing the AC drive is an average pixel optical characteristic in a section of a positive polarity, and the control signal is a negative polarity. of As the optical properties of the average pixel become the same between, the liquid crystal display device characterized by having a data correction means for correcting the data written to each pixel. 9. The data correction unit according to claim 8, wherein the correction of the data to be written in each pixel is performed in consideration of a change in a liquid crystal itself constituting the pixel or a change in an ambient temperature of the liquid crystal. 3. The liquid crystal display device according to 1. 10. A flicker detecting unit for detecting flicker occurring on a display screen, wherein the data correcting unit corrects data to be written to a pixel based on a detection output of the flicker detecting unit so as to eliminate flicker. The liquid crystal display device according to claim 8, wherein: 11. The liquid crystal display device according to claim 8, wherein said control means drives said pixels by plane inversion by said scanning line driving circuit and data line driving circuit. 12. An electronic apparatus comprising the liquid crystal display device according to claim 8.