JP2006267411A - Liquid crystal display device and liquid crystal display method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device and a liquid crystal display method in which even when the polarity of supplied voltage between electrodes is alternately switched, voltage variation between pixel electrodes is small and a sufficiently large transmittance is obtained. <P>SOLUTION: The liquid crystal display device is provided with: a plurality of pixels arrayed like a matrix in intersection parts of a plurality of scanning lines and a plurality of data lines; a scanning line driver connected to the plurality of scanning lines to output scanning signals; and a data line driver connected to the plurality of data lines to output data signals. In the liquid crystal display device, each of the pixels is provided with: a liquid crystal cell 202 where liquid crystal is held between a pair of electrodes; a memory cell 200 for storing data signals supplied through the plurality of data lines and read by a scanning signal supplied through the plurality of scanning lines; and a logic cell 201 connected to one of a pair of electrodes in common on the basis of the data signal read from the memory cell 200 to switch voltage supplied from the external between two values and output the switched voltage. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device and a liquid crystal display method, and more particularly to control of electrode voltage with respect to liquid crystal transmittance.

    In a liquid crystal driving element represented by LCOS or the like, a large number of pixel circuits are arranged in a matrix, and an external video signal is written in a memory cell provided for each pixel, and this signal is provided for each pixel. The image is displayed by driving the liquid crystal to the reflective electrode. The liquid crystal is sandwiched between a reflective electrode and a common electrode (counter electrode) provided on the opposite side, and displays an image by controlling the light transmittance by the potential difference between the two electrodes. The common electrode applies a constant voltage in common to all pixels.

    As shown in FIG. 4A, a conventional liquid crystal display device includes a data line driver 100 that supplies a display signal D100 from an external video signal to the pixel circuit 101 in accordance with display timing, and FIG. A pixel circuit 101 including a plurality of pixels 50 including a memory cell 51, a selector 52, a pixel electrode, and a liquid crystal 53 having a common electrode, and a scanning line driver 102 that controls display timing for each scanning line of the pixel circuit 101. And a voltage setting 103 for setting two power supply voltages to be supplied to the common electrode of the pixel circuit 101.

Next, the operation of the conventional liquid crystal display device will be described with reference to FIGS.
4A and 4B are diagrams showing an outline of a conventional liquid crystal display device, FIG. 4A is a block diagram, and FIG. 4B is a diagram for explaining a pixel configuration.
5A and 5B are diagrams for explaining the change in transmittance of the liquid crystal with respect to the voltage supplied to the pixel electrode. FIG. 5A is a diagram illustrating the transmission characteristics of the liquid crystal with respect to the driving voltage between the electrodes. It is a figure which shows the voltage change supplied to a pixel electrode, (C) is a figure which shows input data, (D) is a figure which shows the transmittance | permeability of the liquid crystal with respect to the drive voltage between electrodes.
FIG. 6 is a diagram showing a selector logic table in a pixel.

 As shown in FIG. 4B, the display signal D100 is supplied as input data to the memory cell 51 of the pixel 50, and the display timing data V100 is supplied at the timing when the input data is stored. Then, the display data M01 read from the memory cell 51 is added to the selector 52. The selector 52 is supplied with a voltage E100 of + 5V and a voltage E101 of -5V from the voltage setting 103.

 Then, the selector output S01 is added from the selector 52 to the pixel electrode of the liquid crystal 53 based on the selector logic table shown in FIG. When the display data M01 is 0, the selector output S01 is 0, and one common electrode of the liquid crystal is connected to the GND in common for all pixels, so the voltage between the electrodes is 0 and the liquid crystal remains opaque.

 On the other hand, when the display data M01 is 1, the selector output S01 switches the voltage E100 and the voltage E101 in the selector 52 to alternately switch the supply voltage of the pixel electrode between + 5V and -5V polarities. Supply. By doing so, the liquid crystal becomes transparent when the display data M01 is 1, and the polarity of the liquid crystal does not shift to one side, and the performance of the liquid crystal is not deteriorated.

In this manner, the supply voltage of the pixel electrode is set to both + 5V and -5V polarities, so that the performance of the liquid crystal is maintained well. Patent Document 1 also describes that two voltages are supplied to all the plurality of pixels 50 as shown in FIG.
JP 2002-515606 A

However, always having both positive and negative polarities for the supply voltage to the pixel electrode increases the load on the capacity of the power supply unit and the wiring unit, and the voltage fluctuation between the pixel electrodes becomes + 5V to -5V. As shown in FIG. 6C, when the data input is 1, the voltage between the pixel electrodes is switched alternately for all the pixel electrodes at the same time as shown in FIG. When moving to the polarity, the voltage difference becomes large and the voltage shift is gradually delayed as shown in FIG.
For this reason, as shown in FIG. 6A, the transmittance of the liquid crystal at the moment when the polarity of the supply voltage is switched based on the transmittance of the liquid crystal with respect to the drive voltage between the pixel electrodes in FIG. There is a problem that the image quality of the video signal to be displayed on the liquid crystal display device is deteriorated because the image quality is lowered at the delay portion without being raised.

 Accordingly, the present invention has been made to solve the above-described problems, and reduces the burden on the capacity of the power supply unit and the wiring unit, and alternately switches the polarity of the supply voltage between the electrodes in the pixel electrode. However, it is an object of the present invention to provide a liquid crystal display device and a liquid crystal display method in which a voltage variation between pixel electrodes is small and sufficient transmittance is obtained, and an image quality of a video signal to be displayed is good.

According to a first aspect of the present invention, a plurality of scanning lines arranged in a horizontal direction, a plurality of data lines arranged in a vertical direction, and a plurality of scanning lines and data lines are arranged in a matrix at intersections. A plurality of pixels connected to the scanning line and the data line; a scanning line driver connected to the plurality of scanning lines for outputting a scanning signal; and a data signal connected to the plurality of data lines for outputting a data signal. In the liquid crystal display device including the data line driver, the plurality of pixels store a liquid crystal cell in which liquid crystal is sandwiched between a pair of electrodes and a data signal supplied via the plurality of data lines, Based on a memory cell read by a scanning signal supplied via a plurality of scanning lines and the data signal read from the memory cell, it is commonly connected to one of the pair of electrodes and supplied from the outside. To provide a liquid crystal display device comprising a logic cell, further comprising a for switching the output between the two value determined the voltage in advance.
According to a second aspect of the present invention, a plurality of pixels each having a liquid crystal cell sandwiched between a pair of electrodes has a matrix at intersections of a plurality of scanning lines for supplying scanning signals and a plurality of data lines for supplying data signals. In the liquid crystal display method for displaying an image by supplying the scanning signal in a state where the data signal is supplied to the plurality of pixels and connected to the scanning line and the data line. Is stored in the memory, the scanning signal is supplied to the memory, the data signal is read, and the voltage supplied to the pair of electrodes is determined in advance by logic based on the data signal read from the memory. There is provided a liquid crystal display method characterized in that output is performed by switching between two specified values.

  According to the liquid crystal display device of the present invention, the plurality of scanning lines arranged in the horizontal direction, the plurality of data lines arranged in the vertical direction, and the intersection of the plurality of scanning lines and the data lines are arranged in a matrix. A plurality of pixels connected to the scanning lines and the data lines, a scanning line driver connected to the plurality of scanning lines and outputting a scanning signal, and a data line driver connected to the plurality of data lines and outputting a data signal; In the liquid crystal display device, the plurality of pixels store a liquid crystal cell in which liquid crystal is sandwiched between a pair of electrodes and a data signal supplied via the plurality of data lines, and pass through the plurality of scanning lines. Based on a memory cell read by the supplied scanning signal and a data signal read from the memory cell, it is commonly connected to one of the pair of electrodes, and the voltage supplied from the outside is switched between two predetermined values. By providing a logic cell output, it is possible to increase the transmittance immediately switching the polarity of the supply voltage between the pixel electrodes.

An optical disk recording / reproducing apparatus according to an embodiment of the present invention will be described below with reference to FIGS.
FIG. 1 is a diagram showing an outline of a liquid crystal display device according to an embodiment of the present invention, (A) is a diagram showing a block diagram, and (B) is a diagram for explaining a configuration of a pixel.
FIG. 2 is a diagram showing a logic cell logic table.
3A and 3B are diagrams for explaining the change in transmittance of the liquid crystal with respect to the voltage supplied to the pixel electrode. FIG. 3A is a diagram illustrating the transmission characteristics of the liquid crystal with respect to the driving voltage between the electrodes. It is a figure which shows the voltage between electrodes supplied to a pixel electrode, (C) is a figure which shows the voltage input applied to a common electrode, (D) is a figure which shows data input.

 As shown in FIG. 1A, a liquid crystal display device according to an embodiment of the present invention includes a data line driver 1 for supplying a display signal D0 based on an external video signal to a pixel circuit 2 in accordance with a display timing, 1B, a pixel circuit 2 including a plurality of pixels 20 including a memory cell 200, a logic cell 201, a pixel electrode, and a liquid crystal cell 202 having a common electrode, and display timing for each scanning line of the pixel circuit 2. And a voltage selection 4 for supplying a voltage to the common electrode of the pixel circuit 2.

 A plurality of scanning lines V1, V2, V3,. . . (Hereinafter abbreviated as a plurality of scanning lines) and a plurality of data lines D1, D2, D3,. . . (Hereinafter abbreviated as a plurality of data lines), a plurality of pixels 20 arranged in a matrix at intersections of the plurality of scanning lines and the data lines, and connected to the plurality of scanning lines and the plurality of data lines, and a plurality of scannings. In a liquid crystal display device including a scanning line driver 3 connected to a line and outputting a scanning signal, and a data line driver 1 connected to a plurality of data lines and outputting a data signal, the plurality of pixels 20 include liquid crystal A liquid crystal cell 202 sandwiched between a pair of electrodes, a memory cell 200 that accumulates a data signal D1 supplied via a plurality of data lines, and is read by a scanning signal V0 supplied via the plurality of scanning lines, Based on the data signal M0 read from the memory cell 200, a logic circuit connected in common to one of the pair of electrodes and switching and outputting the voltage S0 supplied from the outside between two predetermined values. And Kuseru 201, but with a.

Next, the operation of the liquid crystal display device will be described.
As shown in FIG. 1B, the memory cell 200 of the pixel 20 is supplied with the display signal D1 as input data and the display timing data V0 at the timing when the input data is stored. Then, the display data M0 read from the memory cell 200 is added to the logic cell 201. The logic cell 201 is supplied with a voltage S0 that is alternately switched between + 5V and 0V from the voltage selection 4.

Then, the voltage output M1 from the logic cell 201 is applied to the pixel electrode of the liquid crystal 53 based on the logic cell logic table shown in FIG. Further, in the lower part of FIG. 2, the transmission characteristics indicating the transmittance of the liquid crystal when the interelectrode voltage (M1-S0) is used as the drive voltage are clearly shown.
Now, when the display data M0 is 0, when the voltage input S0 is 0, the voltage output M1 is 0 based on the logic cell logic table, so the voltage between the electrodes (M1-S0) is 0. The transmittance is zero. Further, when the voltage input S0 is + 5V, the voltage output M1 is + 5V based on the logic cell logic table. Therefore, the interelectrode voltage (M1-S0) is also 0, so the transmittance of the liquid crystal is 0.

 Next, when the display data M0 is 1, and the voltage input S0 is 0, the voltage output M1 is + 5V based on the logic cell logic table, and therefore the voltage between the electrodes (M1-S0) is + 5V. The transmittance is Max. When the voltage input S0 is + 5V, the voltage output M1 is 0 based on the logic cell logic table, and the interelectrode voltage (M1-S0) is -5V. Therefore, the transmittance of the liquid crystal is Max.

Based on this logic cell logic table, as shown in FIG. 3, when the data input is 1, even if the voltage input is alternately switched between 0 and + 5V, 0 → 5V, 5V → 0 and the pixel electrode are common. The switching voltage of the electrodes is very small. Therefore, the voltage delay amount when switching the interelectrode voltage (M1-S0) is small as shown in FIG. Therefore, as shown in FIG. 3A, the liquid crystal transmittance Max can be obtained almost during the period when the data input is 1.
The switching of the voltage input is set to be performed a plurality of times so as to prevent the deterioration of the liquid crystal in one scanning line period by the switching signal V3 obtained from the scanning line driver 3.

 As described above, according to the embodiment of the present invention, the polarity of the supply voltage between the electrodes to the pixel electrode can be changed by switching the polarity of the supply voltage between the pixel electrodes of the liquid crystal using only the supply voltage of + 5V. Even if these are alternately switched, a liquid crystal display device can be obtained in which the voltage fluctuation between the pixel electrodes is small and sufficient transmittance is obtained, and the image quality of the video signal to be displayed is good.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the outline | summary of the liquid crystal display device which concerns on embodiment of this invention, (A) is a figure which shows a block diagram, (B) is a figure for demonstrating the structure of a pixel. It is a figure which shows a logic cell logic table. 4A and 4B are diagrams for explaining a change in transmittance of liquid crystal with respect to a voltage supplied to the pixel electrode, FIG. 3A is a diagram illustrating transmission characteristics of the liquid crystal with respect to a driving voltage between the electrodes, and FIG. FIG. 4C is a diagram showing voltage input applied to the common electrode, and FIG. 4D is a diagram showing data input. It is a figure which shows the outline | summary of the conventional liquid crystal display device, (A) is a figure which shows a block diagram, (B) is a figure for demonstrating the structure of a pixel. 4A and 4B are diagrams for explaining a change in transmittance of liquid crystal with respect to a voltage supplied to the pixel electrode, FIG. 3A is a diagram illustrating transmission characteristics of the liquid crystal with respect to a driving voltage between the electrodes, and FIG. (C) is a diagram showing input data, and (D) is a diagram showing the transmittance of the liquid crystal with respect to the drive voltage between the electrodes. It is a figure which shows the selector logic table | surface in a pixel.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Data line driver, 2 ... Pixel circuit, 3 ... Scan line driver, 4 ... Voltage selection, 20 ... Pixel, 200 ... Memory cell, 201 ... Logic cell, 202 ... Liquid crystal cell

Claims (2)

A plurality of scanning lines arranged in the horizontal direction, a plurality of data lines arranged in the vertical direction, and arranged in a matrix at intersections of the plurality of scanning lines and the data lines, and the scanning lines and the data lines A liquid crystal comprising: a plurality of connected pixels; a scanning line driver connected to the plurality of scanning lines and outputting a scanning signal; and a data line driver connected to the plurality of data lines and outputting a data signal. In the display device,
The plurality of pixels are:
A liquid crystal cell in which liquid crystal is sandwiched between a pair of electrodes;
A memory cell that stores data signals supplied through the plurality of data lines and is read by the scanning signals supplied through the plurality of scanning lines;
A logic cell connected in common to one of the pair of electrodes based on the data signal read from the memory cell and switching a voltage supplied from the outside between two predetermined values;
A liquid crystal display device comprising: A plurality of pixels each having a liquid crystal cell sandwiched between a pair of electrodes are arranged in a matrix at intersections of a plurality of scanning lines for supplying scanning signals and a plurality of data lines for supplying data signals. In a liquid crystal display method for displaying an image by supplying the scanning signal in a state where the data signal is connected to the plurality of pixels and connected to the data line,
In a state where the data signal is stored in the memory, the scanning signal is supplied to the memory, and the data signal is read.
A liquid crystal display method characterized in that, based on the data signal read from the memory, a voltage to be supplied to the pair of electrodes is switched between two values determined in advance by logic and output.