JPH0460583A - Driving circuit of liquid crystal display device - Google Patents

Abstract

PURPOSE:To adjust white balance through easy operation by generating a driving voltage with a voltage value selected by a color selecting circuit. CONSTITUTION:The driving circuit is provided with the color selecting circuit 9 together with a serial-parallel converting circuit 1, decoders 21 - 2n, adn selecting circuits 31 - 3n. Namely, when a color filter array of RGB lateral stripes is employed, the color selecting circuit 9 switches a selection switch 11 to one of terminals A - C to be selected in every horizontal scanning period under the control of a color selection signal CS inputted from a terminal 10 to select one voltage corresponding to the color array of the color filter among VA - VC, thereby outputting it. For the purpose, the voltages VA - VC of the terminals A - C to be selected are adjusted to set the voltage value selected by the color selecting circuit 9 optionally, and then the voltage is adjusted according to colors and inputted to adjust the white balance.

Description

[Detailed Description of the Invention] [Purpose of the Invention (Field of Industrial Application) The present invention relates to a drive circuit for an active matrix type liquid crystal display device, and in particular to a drive circuit for a liquid crystal display device that enables adjustment of white balance. Regarding.

(Prior Art) In recent years, high-definition active matrix type liquid crystal display devices suitable for personal computers and stations have been developed.

In this type of liquid crystal display device, signal lines and scanning lines are formed in a matrix within a liquid crystal cell, and pixel electrodes and switching elements such as thin film transistors are provided at the intersections of these lines. By sequentially turning on and off each horizontal line, a signal voltage is selectively supplied to the pixel electrode, and the signal voltage is applied to the liquid crystal sandwiched between the pixel electrode and the facing electrode, passing through the liquid crystal. By optically modulating the light, multi-gradation or full-color images are displayed.

The signal voltage is supplied by a signal line drive circuit connected to the liquid crystal cell. Broadly speaking, the signal line drive circuit inputs an analog video signal, sequentially samples and holds the voltage value of this signal, obtains a signal voltage corresponding to one horizontal line, and outputs this from an output terminal. The internal circuit is configured in an analog manner, and the digital video signal is input, and this digital value is processed internally to obtain an analog signal voltage, which is output from the output terminal. There are things that have been done.

A digitally configured signal line drive circuit is described in detail in, for example, Japanese Unexamined Patent Publication No. 161495/1982, but its internal configuration and operation will be briefly described here.

FIG. 5 shows the internal configuration of a conventional digital configuration signal line drive circuit.

That is, the signal line drive circuit mainly includes a serial-to-parallel conversion circuit 1, a decoder 2, and a selection circuit 3.

The serial/parallel conversion circuit 1 mainly consists of shift registers, latches, etc., and converts the input multi-gradation digital video signal (brightness gradation m bits) 4 to the dot input from the terminal 5. Clock CPH and terminal 6
Serial-to-parallel conversion is performed so that signal voltages can be simultaneously supplied to a plurality of (n) signal lines of the liquid crystal cell by controlling the horizontal activation signal STH inputted from the horizontal activation signal STH.

The decoders 21 to 2n are the serial/parallel conversion circuit 1
The m-bit pixel data converted and outputted by is decoded, and a signal for controlling on/off of a plurality of switches 7 inside the selection circuits 31 to 3n is outputted.

The selection circuits 31 to 3n select a predetermined one from q types of drive voltages 1, V2...Vq supplied to the input terminals according to control signals from the decoders 21 to 2n, and is output from the output terminals 81 to 8n. Note that these drive voltages v1, 2...Vq are determined by the selection circuit 31.
.about.3n, and has 2 to the power of m types of values corresponding to the m bits of gradation of the digital video signal 4.

In the signal line drive circuit configured in this way, in response to the input of the m-bit digital video signal 4, one voltage value is selectively output from 2 m types of voltages, and is output to the signal line of the liquid crystal cell. Supplied. Therefore, the signal voltage output from this drive circuit is, for example, R,
When supplied to a color cell that has a color filter consisting of G and B, the number of colors that can be displayed is 3 to the m power of 2.
It becomes multiplicative color.

Specifically, when a color cell with R, G, and B color filters is driven by inputting a 3-bit, 8-gradation digital video signal 4, 512 colors can be displayed.

(Problem to be Solved by the Invention) In the conventional digital configuration signal line drive circuit described above, drive voltages of a number (types to the m power of 2) corresponding to the number of gradations are commonly supplied to the selection circuits 31 to 3n. Therefore, if this voltage value is changed, the supplied signal voltages will be R, G,
Each of B will always change simultaneously.

Therefore, it is not possible to independently adjust the drive voltage for each of R, G, and B, making it extremely difficult to adjust the white balance.

The present invention has been made in order to solve such problems with conventional drive circuits, and it is an object of the present invention to provide a drive circuit for a liquid crystal display device in which white balance can be adjusted with a simple operation.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a serial-to-parallel conversion circuit that converts an input multi-gradation digital video signal into pixel data, and a serial-to-parallel conversion circuit that converts an input multi-gradation digital video signal into pixel data. an active matrix type liquid crystal display comprising: a decoder that converts the output voltage; and a selection circuit that is controlled by the output from the decoder and selects and outputs a predetermined one from among q types of drive voltages supplied to an input terminal. In the drive circuit of the device, a color selection circuit is provided which selects one voltage from adjustable voltages corresponding to the color filter arrangement of the liquid crystal cell, and this color selection circuit selects one voltage according to the color filter arrangement. A driving circuit for a liquid crystal display device, characterized in that the q types of driving voltages are created from selected voltage values, or
In the drive circuit of the active matrix type liquid crystal display device, the drive voltage selected by the selection circuit has different potentials corresponding to the color filter arrangement of the liquid crystal cell, and one type of potential depending on the color filter arrangement.
A driving circuit for a liquid crystal display device, comprising at least one color selection circuit that selects one potential.

(Function) According to the drive circuit for a liquid crystal display device of the present invention, white balance can be adjusted with a simple operation.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a driving circuit of a liquid crystal display device according to an embodiment of the present invention. This embodiment shows a driving circuit when the color filter array of a liquid crystal cell is, for example, an RGB horizontal stripe array, in which the horizontal line consists of pixels of one color and the vertical line consists of pixels of three colors. It is.

In FIG. 1, the same parts as in FIG. 5 are given the same reference numerals, and their explanation will be omitted.

The drive circuit of this embodiment includes, in addition to the serial-to-parallel conversion circuit, the decoder 2, and the selection circuit 3, a color selection circuit 9 that operates as shown below.

That is, in the case of the above-described RGB horizontal striper filter arrangement, the color selection circuit 9 selects the selection switch 11 by controlling the color selection signal C8 input from the terminal 10.
The selected terminals A, B,
C, select one voltage among VA, VB, and VC that corresponds to the color arrangement of the color filter, and output it.

Here, VA-VC is a square wave voltage whose voltage value can be adjusted.

This voltage output from the color selection circuit 9 and the terminal 1
Center voltage Vsig common to VA-VC input from 2
From c, q types of drive voltages V1, V2...V
q is created, and one of these is output to the selection circuit 3.

For example, suppose that 2 pixels correspond to selected terminal A, 0 pixels correspond to selected terminal B, and 8 pixels correspond to selected terminal C, and R, G, B
When horizontal stripes are formed in the order of During the period, the selected terminal B
is switched to select terminal VB, and further, in the next one horizontal line period, the terminal is switched to selected terminal C and VC is selected. Then, during each horizontal line period, VA, VB, and VC (!: Vsigc) are selected and output.

From these, drive voltages V+, V2, . . .
~8n is output.

Therefore, by adjusting the voltage values VA to VC of the selected terminals A, B, and C and arbitrarily setting the voltage value selected by the color selection circuit 9, the signal voltage supplied to each color pixel can be changed to the other color. is set regardless of

As described above, according to the embodiment shown in FIG. 1, the white balance can be adjusted by adjusting and inputting the voltage value VA-VC according to the display color.

FIG. 2 is a block diagram showing the configuration of another embodiment of the present invention.

In this embodiment, the number of selected terminals in the color selection circuit 9 is A,
There are 82 of them. When the color filter array of the liquid crystal cell is an RGBG square array or an RGBW square array, and the horizontal line consists of pixels of two colors, the liquid crystal cell is driven from two directions (from one direction to the odd numbered signal line, etc.). This is a circuit that drives even-numbered signal lines from the same direction.

In the embodiment shown in FIG. 2, the selection switch 11 of the color selection circuit 9 receives the color selection signal C8 input from the terminal 10.
, the selected terminal A is selected every horizontal line period.
, B, and the voltage VA or VB is output.

Common center voltage with output VA or VB ■sig
Driving voltages V1, v2, .

Next, the embodiment shown in FIG. 3 will be described.

The drive circuit of this embodiment includes a serial-to-parallel conversion circuit 1, a decoder 2, a selection circuit 3, and a number of color selection circuits 9 corresponding to the number of signal lines.

The serial/parallel conversion circuit 1 converts the input multi-gradation digital video signal 4 into a dot clock CPH input from a terminal 5 and a horizontal activation signal S input from a terminal 6.
By controlling the TH, serial-to-parallel conversion is performed so that signal voltages can be simultaneously supplied to a plurality of (n) signal lines of the liquid crystal cell.

The decoders 21 to 2n are the serial/parallel conversion circuit 1
The pixel data corresponding to one horizontal line converted and output is decoded, and a signal is output to the selection circuits 31 to 3n to control on/off a plurality of switches 7 therein.

The selection circuits 31 to 3n select and output one predetermined voltage from q types of drive voltages V1, VB, . . . .

The color selection circuits 91 to 9n divide the voltage output from the selection circuits 31 to 3n according to the color arrangement of the color filter of the liquid crystal cell, and also divide the voltage outputted from the selection circuits 31 to 3n into arbitrarily set adjustment voltages VA,
1 from VB and VC that corresponds to the color arrangement of the color filter
The output terminals 81 to 8n output the voltage obtained by selecting two voltages and adding the voltage obtained by dividing these two voltages by resistance.

In the case of the above-mentioned RGB horizontal stripe color filter array, one horizontal line consists of pixels of one color, so the same color is selected by each of the color selection circuits 91 to 9n and input from the terminal 10. Under the control of the color selection signal C8, the selection switches 111 to lln are set to the selected terminal A corresponding to the color arrangement of the color filter for each horizontal line period.
S.B.

Switch to either C.

For example, suppose that selected terminal A corresponds to an R pixel, selected terminal B corresponds to a G pixel, and selected terminal C corresponds to a B pixel, and R, G, H
When horizontal stripes are formed in this order, the color selection circuits 91 to 9n always select the selected terminal A in the first horizontal line period, and select the selected terminal B in the next horizontal line period , and selects the selected terminal C in the next one horizontal line period. Then, in each horizontal line period, the voltage selectively outputted by the selection circuit 3 and the color selection circuit 9
Adjustment voltages VA, VB selected from 1 to 9n.

The voltage obtained by resistor-dividing any one of the voltages of VC is output from the output terminals 81 to 81 as a signal voltage to be supplied to each color pixel.
It is output from 8n.

In this way, the voltage values VA to VC of the selected terminals ASB and C are arbitrarily set regardless of other colors, and the drive voltages V1 and V corresponding to the multi-gradation digital video signal 4 are set according to the display color.
B: Input Vq and adjustment voltages VA, VB, VC, R, G.

It becomes possible to adjust the white balance independently of B.

In the embodiment shown in FIG. 4, color selection circuits 91 to 9n
The selection switches 111 to lln are switched to either the selected terminal A or H every horizontal line period under the control of the color selection signal C8 input from the terminal 10, and the adjustment voltage of VA or VB is switched. selected. Then, the voltage selected from among the drive voltages V1, V2...Vq by the selection circuit 3 and the adjustment voltage VA or VB selected by the color selection circuits 91 to 9n are obtained by resistance division. The voltage is supplied to each color pixel as a signal voltage to the 8-power terminal 8.
Output from 1 to 8n.

In the embodiments shown in FIGS. 2 and 4, the signal voltage supplied to each color pixel is set regardless of other colors, so it is possible to adjust the white balance independently for R, G, and B. Become.

Further, the drive circuit of the embodiment shown in FIGS. 2 and 4 is as follows:
For example, it is necessary to provide two circuits above and below the screen of a liquid crystal display device.

Furthermore, in the above embodiments, the cases where the number of selected terminals in the color selection circuit is three and two are explained, but the present invention is not limited to this, and the number of terminals to be selected in the color selection circuit is not limited to this. , the number of terminals to be selected can be set arbitrarily.

Furthermore, the switching control period of the selection switch in the color selection circuit is not limited to the horizontal line period, but can be set to any period.

[Effects of the Invention] As is clear from the above description, according to the drive circuit for a liquid crystal display device of the present invention, white balance can be adjusted with a simple operation.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of a drive circuit for a liquid crystal display device according to the present invention, FIGS. 2 to 4 are block diagrams showing other embodiments of the present invention, and FIG. 1 is a block diagram showing the configuration of a conventional digital configuration signal line drive circuit. FIG. DESCRIPTION OF SYMBOLS 1... Serial-parallel conversion circuit, 2... Decoder, 3... Selection circuit, 4... Multi-gradation digital video signal, 7... Switch, 8... Output terminal, 9... - Color selection circuit, 11... selection switch. Applicant Toshiba Corporation Agent Patent Attorney Sasa Suyama

Claims (2)

[Claims] (1) Serial input multi-gradation digital video signal
A serial-to-parallel converter circuit that converts the pixel data into parallel data; a decoder that decodes the pixel data; a selection circuit for selecting and outputting one of the color filter arrays from among adjustable voltages corresponding to the color filter array of the liquid crystal cell. 1. A drive circuit for a liquid crystal display device, characterized in that a color selection circuit is provided for selecting one color according to the color selection circuit, and the q types of drive voltages are created from the voltage values selected by the color selection circuit. (2) Serial input multi-gradation digital video signal
A serial-to-parallel converter circuit that converts the pixel data into parallel data; a decoder that decodes the pixel data; In the drive circuit for an active matrix liquid crystal display device, the drive circuit includes a selection circuit that selects and outputs one of the following, wherein the drive voltage selected by the selection circuit is one of the types corresponding to the color filter arrangement of the liquid crystal cell. A drive circuit for a liquid crystal display device, comprising at least one color selection circuit having a potential and selecting one potential in accordance with the color filter arrangement.