JPH0695078A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To reduce an external wiring, to increase the latitude of design and to drive the device with reduced power consumption by providing an image data generation part provided with a conversion updating means updating a conversion table of a conversion means in a display part. CONSTITUTION:This device is provided with a display part provided with the conversion means converting color data with k-bit width to the color data with m-bit width (m>k) based on the conversion table and a display means displaying based on the color data with m-bit width from the conversion means, and the image data generation part 11 provided with a frame memory 25 outputting the color data with k-bit width and the conversion updating means updating the conversion table in the conversion means in the display part, and an external wiring 111 connecting between the display part and the image data generation part 11. Then, since the conversion means converting the color data with k-bit width to the color data with m-bit width (m>k) is provided in the display part, the external wirings 111 connecting between the display part and the image data generation part 11 may be connected with k pieces of wirings at most for the transmission of the color data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device having an image data generating section and capable of multi-gradation display.

[0002]

2. Description of the Related Art Liquid crystal displays have come to be used in various fields by taking advantage of their characteristics of light weight and low power consumption. Among them, liquid crystal displays capable of displaying multiple gradations are televisions or personal computers. It is widely used as a display for liquid crystal display devices such as.

The liquid crystal display device has, for example, m signal lines Yi.
(i = 1,2, ..., m) and scanning lines Xj (j = 1,2, ..., m) are arranged in a matrix, and switching elements connected to pixel electrodes are installed at each intersection. A liquid crystal cell in which a liquid crystal layer made of a liquid crystal composition is sandwiched between a first electrode substrate and a second electrode substrate provided with a counter electrode, and driving for applying a driving voltage to each electrode of the liquid crystal cell. It is provided with a liquid crystal display having a circuit section.

The drive circuit section of the sail liquid crystal display is equipped with a signal line Yi.
The signal line drive circuit connected to the scan line Xj, the scan line drive circuit connected to the scan line Xj, and the counter electrode drive circuit connected to the counter electrode.

The signal line drive circuit is a serial / parallel conversion circuit mainly composed of a shift register and a latch circuit,
It is composed of decoders and voltage selection circuits for the number of signal lines Yi, and a drive voltage supply circuit. And
Such a liquid crystal display device includes an image data generation unit that supplies display image data such as color data to the liquid crystal display.

For example, the image data generating section is provided with a 4-bit deep frame memory, and the liquid crystal display is composed of 16 gradations of red (R), green (G) and blue (B) and 2 ¹² (4096) colors. The case where display is possible will be described.

The luminance data of 2 ¹² (4096) colors is 2 ⁴ according to a predetermined rule. (16) Color data of colors, that is, any of 4096 colors
It is converted into 4-bit width color data for selecting 16 colors and stored in the frame memory. From frame memory
4-bit width color data can be selected by the color reference table.
16 colors are selected. Red (R), green (G), and blue (B) colors are converted into 4-bit width color data (12 bits), and are sent to the video signal drive circuit of the display unit via 12 external wires. Is entered.

The 4-bit width color data input to the video signal drive circuit in this way is serial-parallel converted by the serial-parallel converter circuit to become display data corresponding to the number of signal lines Yj of the liquid crystal display device, and each decoder Be led to. Then, the display data is decoded by the decoder, 16 switches in the voltage selection circuit are turned on / off, and the number of display gradations supplied from the drive voltage supply circuit, that is, 16 drive voltages V1
, V2, ..., V16 are selected and applied to each signal electrode. Since the liquid crystal display device needs to be driven by an alternating current in order to prevent deterioration of the liquid crystal composition, the polarities of the driving voltages V1, V2, ..., V16 are inverted with respect to the counter electrode potential every frame period. .

[0009]

By the way, in a liquid crystal display device equipped with such a liquid crystal display, an increase in the number of gradations is desired in order to meet the demand for higher definition. However, if an attempt is made to increase the number of gradations of the liquid crystal display, naturally the number of external wiring lines for transmitting color data, which is required for the number of gradations, is increased.

In a laptop computer or the like, since the display section composed of a liquid crystal display and the image data generating section are often connected via a movable part, such an increase in the number of external wiring is caused by the movable part. It imposes various restrictions on the configuration. In addition, such external wiring, in terms of signal transmission,
It is necessary to provide matching terminations, which requires extra power.

The present invention has been made in view of the above circumstances, and reduces external wiring between the display section and the image data generating section to increase the degree of freedom in design and to achieve low power consumption driving. The purpose of the present invention is to provide a liquid crystal display device that can be used.

[0012]

The liquid crystal display device of the present invention includes a conversion means for converting color data having a width of k bits into color data having a width of m bits (m> k) based on a conversion table. Display unit including display means for displaying based on m-bit width color data, storage means for outputting k-bit width color data, conversion table update for updating the conversion table of the conversion means of the display unit An image data generating unit including means,
It is characterized in that an external wiring for connecting the display unit and the image data generating unit is provided.

Further, the display means of this liquid crystal display device is provided with an array substrate in which pixel electrodes are arranged via switch elements at respective intersections of video signal lines and scanning signal lines arranged in a matrix. It is characterized by that. Also,
The liquid crystal display device of the present invention is further characterized in that the conversion table is updated within the blanking period.

[0014]

According to the liquid crystal display device of the present invention, as described above, color data having a width of k bits is displayed on the display unit with a width of m bits (m> k).
Since the external wiring for connecting the display unit and the image data generating unit is provided with the conversion means for converting the color data into the color data, it is sufficient to connect at most K external wirings for transmission of the color data.

Therefore, it is sufficient to connect the external wiring, which has been required at least m in the past, with the external wiring for transmitting the color data of k and the external wiring for updating the conversion table of the conversion means. . Therefore, the number of external wires for connecting the display unit and the image data generating unit can be significantly reduced.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the image data generating section is provided with a 4-bit deep frame memory, and the liquid crystal display device has a 16-bit depth.
It consists of gradations of red (R), green (G), and blue (B). 2 ¹² (40
96) A liquid crystal display device capable of color display will be described in detail with reference to the drawings.

FIG. 1 is a schematic perspective view of a liquid crystal display device (1) of the present embodiment, in which a main body (3) on which a keyboard (5) is arranged.
The display unit (201) is movably connected and held via the movable unit (101).

An image data generating section (11) is arranged inside the main body (3), and the image data generating section (11) and the display section (201) are connected via an external wiring (111) via a movable section (101). It is connected. Further, the liquid crystal display device (1) is provided with a connection terminal (7) for connection with a CRT device in order to realize display on the CRT device. First, the image data generator (11) provided inside the main body (3) will be described with reference to FIG.

A drawing processor (21) for generating a control signal, a memory address, brightness data, etc. by a drawing command from a central processing unit (not shown), etc., and 16 (converted based on the brightness data of the drawing processor (21) Two ^four ) A frame memory (25) with a depth of 4 bits for storing one display image of color and a frame memory control means (27) for controlling the frame memory (25) are provided, and 4 bits from the frame memory (25) are provided. The color data is connected to the color reference table (29) via the frame memory control means (27) and to the four external wirings (111) for input to the display section (11).

Color reference table in the image data generator (11)
The 4-bit color data input to (29) is the drawing processor.
Red (R) is selected so as to select 2 ¹² (4096) colors based on the color reference table control signal (CCS) and the color reference data (CD) input from the color reference data conversion circuit (31) from (21). ), Green (G), and blue (B) are converted into 4-bit color data and connected to the CRT terminal.

The color reference table control signal (CCS) and the color reference data (CD) input from the drawing processor (21) to the color reference data conversion circuit (31) are passed through the color reference data conversion circuit (31). The color reference data (CD) in the color reference table (29) is updated and converted into serial color reference data (SCD), and then the display unit (11) is connected via the external wiring (111).
The color lookup table (243) (see FIG. 3) is updated almost simultaneously.

As shown in FIG. 3, the display unit (201) has a plurality of video signal lines (211) and scanning signal lines (213) arranged in a matrix, and a switch element (215) at each intersection. A matrix electrode array (210) formed by connecting a pixel electrode (217) and an auxiliary capacitance line (219) for forming an auxiliary capacitance (Cs) via a common electrode commonly facing each pixel electrode (217). A liquid crystal (23) is provided between the counter substrate (220) provided with (221).
1) is sandwiched. And the pixel electrode (217)
The liquid crystal (231) in the region where the common electrode (221) and the common electrode (221) overlap is displayed in response to the potential difference between the electrodes.

On such a matrix array substrate (210), a video signal line driving circuit (241) for driving the video signal line (211) and a scanning signal line driving circuit for driving the scanning signal line (213). A circuit (261) is provided.

The video signal line drive circuit (241) receives the color data of 4 bit width inputted from the image data generator (11) through the external wiring (111) as red (R), green (G) and blue. (B) 4 each
The color reference table (243) to be converted into bit color data, and the red (R), green (G), and blue (B) 4-bit color data converted by the color reference table (243) correspond to each pixel. Shift register that serial-parallel converts to pixel data and holds
(245), a decoder (247) for decoding the pixel data output from the shift register (245), and a 16-level drive voltage (V1 supplied from the drive voltage supply circuit (251) by the output of the decoder (247). ) To (V16) are selected for each vertical scanning period and output to the video signal line (211).

As described above, the video signal line drive circuit (24
1) The color reference table (243) provided inside is the serial color reference data (SCD) supplied from the image data generator (11).
The selected color is updated by. By thus configuring the liquid crystal display device (1), it is possible to display 2 ¹² colors by inputting 4-bit width color data to the video signal line drive circuit (241).

Therefore, according to the liquid crystal display device (1) of the present embodiment, the connection of the color data between the image data generating section and the display section is made by the conventional 12 to 4 external wirings (11). All you have to do is

By the way, in this embodiment, since the luminance data is converted in addition to the above-mentioned color data, the image data generator
Between the (11) and the display (201), the serial color reference data (SCD
) Is required to be newly provided with external wiring. However, even if such external wiring is newly provided, it is possible to greatly reduce the number as compared with the conventional 12 external wirings. For this reason, according to the present embodiment, expensive external wiring is reduced, and moreover, the degree of freedom in design is increased and the liquid crystal display device is improved.
(1) can be configured.

In the above embodiment, the color reference table
The color reference data (CD) in (243) is updated every one vertical scanning period, but preferably the serial color reference data (SCD) is updated in the color reference data (CD). Only when it is good.

The timing of updating the color reference data (CD) in the color reference table (243) is, for example, during the vertical blanking period (a period during which one vertical scanning period is not performed) in a CRT device. Therefore, the cable for transmitting the serial color reference data can be saved.

[0030]

As described above, according to the present invention, the external wiring between the display section and the image data generating section is reduced,
It is possible to obtain a liquid crystal display device which has a high degree of freedom in design and can be driven with low power consumption. Therefore, the present invention is particularly suitable for a liquid crystal display device which performs further multi-gradation display.

[Brief description of drawings]

FIG. 1 is a schematic perspective view of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of an image data generation unit of the liquid crystal display device in FIG.

FIG. 3 is a schematic configuration diagram of a display unit of the liquid crystal display device in FIG.

[Explanation of symbols]

 (1) ... Liquid crystal display (11) ... Image data generator (29), (243) ... Color reference table (31) ... Color reference data conversion circuit (111) ... External wiring (201) ... Display section

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location G09G 3/36 7319-5G 5/02 8121-5G

Claims (3)

[Claims] 1. Color data of k-bit width is converted to m-bit width (m
> K) a conversion unit for converting the color data based on the conversion table, a display unit including a display unit for displaying based on the m-bit width color data from the conversion unit, and the k-bit width color Storage means for storing and outputting data,
An image data generating unit including a conversion table updating unit that updates the conversion table of the converting unit of the display unit, and an external wiring that connects the display unit and the image data generating unit. Liquid crystal display device. 2. The display means according to claim 1, further comprising an array substrate in which pixel electrodes are arranged via switch elements at respective intersections of video signal lines and scanning signal lines arranged in a matrix. A liquid crystal display device characterized by the above. 3. A liquid crystal display device, wherein the conversion table according to claim 1 is updated within a blanking period.