JPH0460584A - Driving circuit of liquid crystal display device - Google Patents

Abstract

PURPOSE:To enable adaption to the palette function of a personal computer, etc., by providing a color selecting circuit which selects one specific group of driving voltages corresponding to a color filter array, and selecting the specific group of driving voltages corresponding to the color filter array of a liquid crystal cell. CONSTITUTION: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 line period under the control of a color selection signal CS inputted from a terminal 10 and selects one group of driving voltages corresponding to the color array of the color filter among VA1 - VAq, VB1 - VBq, and VC1 - VCq which are prepared. Then they are outputted as driving voltages V1 - Vq to selecting circuits 31 - 3n. Thus, the color selecting circuit 9 selects on groups of driving voltages among three groups for each color to obtain the driving voltages V1 - Vq, so the adaption to the palette function of a person computer, etc., becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a drive circuit for an active matrix liquid crystal display device, and more particularly to a drive circuit for a liquid crystal display device that enables a palette function.

(Prior Art) In recent years, high-definition active matrix liquid crystal display devices suitable for personal computers and workstations 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. The signal line drive circuit can be broadly divided into internal circuits that input an analog video signal, sequentially sample and hold the voltage value of this signal to obtain a signal voltage corresponding to one horizontal line, and output this from the output terminal. The circuit is constructed in a so-called analog manner, and the internal circuit is constructed in a digital manner, which receives a digital video signal as input, processes this digital value internally to obtain an analog signal voltage, and outputs this from the output terminal. There is something.

As a digitally configured signal line drive circuit, for example, there is a circuit whose details are explained in Japanese Patent Application Laid-Open No. 161495/1982, but here, its internal structure and operation will be briefly explained.

FIG. 3 shows the internal configuration of a conventional digital configuration signal line drive circuit.

That is, the conventional 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 into the input signal from the terminal 5.・By controlling the horizontal start signal STH input from the soto 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.

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

The selection circuits 31 to 3n select one predetermined voltage value from q types of drive voltages v, , v2 . , which are output from output terminals 81 to 8n. Note that the drive voltages v,, v2, . . . , Vq are determined by each selection circuit 31 to
3n, and has values of 2 to the m power corresponding to the number of gradations m bi-soto of the digital video signal 4.

In the signal line drive circuit configured as described above, in response to the input of the m-bit digital video signal 4, one voltage value is selectively output from 2 m types of drive 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
, G, and B, the number of colors that can be displayed is the cube of 2 to the power of m.

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) Many recent personal computers and workstations are compatible with a so-called palette function. In other words, the palette function is a function that allows you to select and display any color from all displayable colors.
For example, it is a function that allows you to select and display any 512 colors out of 260,000 colors.

In the conventional digital configuration signal line drive circuit described above, the selection circuits 31 to 3n are supplied with a number of drive voltages corresponding to the number of gradations (types to the m power of 2), so by changing this value, It is possible to change the display color, but with this method, the voltage supplied to the pixel is
Each SB always changes in the same way, making it impossible to support the original palette function of selecting and displaying any color.

The present invention has been made in order to solve the problems of conventional drive circuits, and provides a drive circuit for a liquid crystal display device that can fully utilize the palette function inherent in personal computers and the like. With the goal.

[Configuration of the Invention (Means for Solving the Problems) A driving circuit for a liquid crystal display device of the present invention comprises a serial-to-parallel conversion circuit that performs serial-to-parallel conversion on an input multi-gradation digital video signal to obtain pixel data. , a decoder that decodes the pixel data, and a selection that is controlled by the output from the decoder and selects a predetermined one from q types of drive voltages supplied to the input terminal and outputs it to the output terminal. In a drive circuit for an active matrix liquid crystal display device having a circuit, a predetermined set of drive voltages is selected corresponding to the color filter arrangement of the liquid crystal cell from among sets of drive voltages prepared according to the color filter arrangement of the liquid crystal cell. The present invention is characterized in that a color selection circuit for selection is provided, and the q types of driving voltages are selected by this color selection circuit.

(Function) According to the drive circuit for a liquid crystal display device of the present invention, a color selection circuit with a simple configuration is added to the conventional drive circuit, and this color selection circuit allows a predetermined drive corresponding to the color filter arrangement of the liquid crystal cell to be performed. By selecting a set of voltages, it is possible to correspond to the palette function of a personal computer or the like.

It is also easy to operate.

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

FIG. 1 is a block diagram showing the configuration of a driving circuit for a liquid crystal display device according to an embodiment of the present invention. This figure shows a driving circuit when a line is made up of pixels of one color and three colors are made up of pixels in the vertical direction.

In FIG. 1, the same parts as in FIG. 3 are given the same reference numerals, and their explanation will be omitted.

The drive circuit of the liquid crystal display device of the embodiment includes a serial-to-parallel conversion circuit 1, a decoder 2, a selection circuit 3, and a color selection circuit 9, which operates as follows.

In other words, in the case of the above-mentioned RGB horizontal stripe color filter arrangement, the color selection circuit 9 selects the selection switch 11 for each horizontal line period (cycle) under the control of the color selection signal C8 input from the terminal 10. Terminals A, B,
C, and three sets of drive voltages prepared in advance (VA, ~VAq, VB+ ~VBq, VC1~V
Cq) Select one set from among (1) that corresponds to the color array of the color filter. Then, this is the driving voltage V1, ■2
. . . Output to the selection circuits 31 to 3n as Vq.

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 RSG, B
When a horizontal stripe is formed in the order of It is switched to the selected terminal B during the horizontal line period, and further switched to the selected terminal C during the next horizontal line period.

In this way, during the first horizontal line period, VA1 to VAq
Noah 4 pressure drive t4 pressure V + , V 2 = 9. v
q, and in the next horizontal line period, VB, ~VBq
The voltages become the drive voltages V1, V2, .

Therefore, VA, ~VAq, VB, ~VBq, VC1~V
By arbitrarily setting the value of the voltage of Cq, the signal voltage supplied to each color pixel can be set regardless of other colors.

As described above, according to this embodiment, in the color selection circuit 9,
Three sets of voltages VA, ~VAq, VB, ~VBq, VC, ~
Since one set for each color is selected from VCq and becomes the drive voltages V1, v2, . . .

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

In this embodiment, the number of terminals to be selected in the color selection circuit 9 is A.
, there are 82. When the color filter arrangement of the liquid crystal cell is an arrangement in which the horizontal line consists of pixels of two colors, such as an RGBG square arrangement or an RGBW square arrangement, the liquid crystal cell is driven from two directions (odd-numbered signals are sent from one direction). This is a circuit that drives even-numbered signal lines from the other direction.

In this embodiment, the color selection signal C input from the terminal 10
5, the selection switch 11 of the color selection circuit 9 is switched to either the selected terminal A or B every horizontal line period, and two sets of drive voltages (
A set of voltage values corresponding to the color arrangement of the color filter is selected from among the voltage values V A +~VAq, VB1~VBq), and the selection circuits 31~3 select the set of voltage values corresponding to the color arrangement of the color filter as drive voltages V7, V2...Vq.
Output to n. In the selection circuits 31 to 3n, a predetermined one is selected from among these drive voltages V1, V2, . . . , Vq, and outputted from the output terminals 81 to 8n.

In this way, the signal voltage supplied to each color pixel is set regardless of other colors, so that it can correspond to the palette function of a personal computer or the like.

Note that, in the embodiment configured as described above, it is necessary to provide two circuits, for example, above and below the screen of the liquid crystal display device.

Furthermore, in the above embodiments, the cases where the number of selected terminals in the color selection circuit 9 is three and two have been described, but the present invention is not limited thereto, and is compatible with the color filter arrangement of the liquid crystal cell. The number of terminals to be selected can be set arbitrarily.

Furthermore, the switching control cycle of the selection switch 11 in the color selection circuit 9 is not limited to the horizontal line cycle, but can be set to any cycle.

Further, in FIG. 1, the color selection circuit 9 can be incorporated into the same circuit as the serial-to-parallel conversion circuit 1, the decoder 2, and the selection circuit 3.

[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, by adding a color selection circuit with a simple configuration to a conventional drive circuit, the palette of a personal computer, etc. can be improved. It is possible to fully support the functions.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a driving circuit of a liquid crystal display device according to an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of another embodiment of the present invention, and FIG. FIG. 2 is a block diagram showing the configuration of a constituent signal line drive circuit. ]... 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 Su Yamasa Figure 3

Claims (1)

[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; In a drive circuit for an active matrix type liquid crystal display device, which is equipped with a selection circuit that selects one of the following and outputs it to an output terminal, one of k sets of drive voltages prepared according to the color filter arrangement of the liquid crystal cell is selected. A drive circuit for a liquid crystal display device, characterized in that a color selection circuit is provided for selecting a predetermined set of color filters corresponding to the color filter arrangement, and the q types of drive voltages are selected by the color selection circuit.