JP2000293142A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve animation display capability by displaying a picture signal written in a liquid crystal display panel by a scanning driver and a signal driver by lighting a back light only in a prescribed time within one field period. SOLUTION: A scanning line 1 at the uppermost part of a liquid crystal display panel is selected by a scanning driver, and then prescribed display data are impressed to a signal line by a signal driver so that the display data can be written in each liquid crystal pixel in the first line. Afterwards, scanning lines 2, 3, 4,..., n are successively scanned and selected, and the display data are written through the signal line in each liquid crystal pixel in the 2nd, 3rd, 4th,..., line. Then, after the writing of the display data is ended, a back light is turned into a lighted state from the back face side of the liquid crystal display panel in a state that the display data written in all the liquid crystal pixels are held so that the liquid crystal display panel can be irradiated with irradiating lights, and the display data can be emission displayed in the residual 1/3 of one field period or less.

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, and more particularly to a liquid crystal display device having improved display capability and display quality when a moving image is displayed on a liquid crystal screen.

[0002]

2. Description of the Related Art In recent years, with the rapid progress in the information society, a display of a television, a personal computer (hereinafter, abbreviated as a personal computer), a monitor of a video camera or the like, or a liquid crystal display as a large display has been used. The spread of the equipment is remarkable. Liquid crystal display (LCD)
Is a conventional cathode ray tube (CR)
Compared to T), it has various features such as thinness, light weight, and low power consumption, and is expected to become a mainstream display in the future. On the other hand, with the advent of the multimedia era, information devices such as personal computers and video cameras have rapidly become widespread, and the targets for information processing have become more diversified. Has increased. Due to this technical background,
The liquid crystal display device is required to have a technology corresponding to a large screen, a high definition, and a high quality, and a moving image display performance (capability) equivalent to that of a CRT.

[0003] The moving image display capability of a conventional CRT and liquid crystal display device will be described below with reference to the drawings.
For comparison of such moving image display capabilities, see, for example, IEICE Technical Report, “Study on Moving Image Quality of Hold-Emission Display Using 8x CRT” (TECHNICA
L PERORT OF IEICE. EID96-4 (1996-06) p.19-p.26). FIG. 3 is a diagram illustrating a relationship between a moving image display capability and a display method. Generally, as an image display method, an impulse type [FIG. 3A], a hold type [FIG.
(B)] and an exponential type [FIG. 3 (c)] are known, and the display method of the liquid crystal display device is classified into an exponential type.

As shown in FIG. 3 (c), in the case of a transmission type liquid crystal display device, a scanning line (also referred to as a gate line) is sequentially arranged from the upper side to the lower side of the screen while the backlight is always on, as shown in FIG. ), And display data (image signals) are sequentially written into the liquid crystal pixels. Here, since the liquid crystal pixel is formed of a capacitor, the display data is displayed on the liquid crystal display panel by accumulating the signal voltage of the display data applied to the liquid crystal pixel as an electric charge and holding it for a certain period of time. You. Such a display operation is repeated in the next field. At this time, the charge accumulated in the pixel capacitance gradually decreases with the passage of time within one field period, so that the display brightness (luminance) changes. The display method in which the display data holding state gradually decays exponentially is called an exponential type.

On the other hand, the impulse type is a display system in which a display screen is turned on for a specific short time within one field period as shown in FIG. 3A, and is represented by a CRT.
This method utilizes the afterimage effect of human vision. For example, in the case of a CRT, an operation is performed in which display data is written into a phosphor for a very short time to emit light, and then the luminance gradually decreases. Is repeated, and at the stage where each display data disappears, the image reflected as an afterimage by the human eye expresses a continuous movement. That is, at the time of switching of the field, the display data of the previous field has already disappeared. As shown in FIG. 3B, the hold-type display system is a system in which display data once written is held and displayed with almost no attenuation, and includes a plasma display panel (PDP) and the like. Is represented by

As described above, in the impulse-type display system, by preventing display data of the previous field from remaining on the screen of the next field, it is recognized as an afterimage only by human vision and motion You can watch even fast-moving videos without discomfort. Therefore, CR
As is clear from the display at T (television), among the above-described display methods, the impulse type is the most suitable as a method for displaying a moving image, and has excellent moving image display capability.

[0007]

As described above, in the liquid crystal display device, as shown in FIG. 4, an exponential display system is employed, so that the backlight is constantly irradiated, and The data is sequentially scanned from the upper scanning line of the liquid crystal display panel (scanning lines 1, 2, 3,..., N), and the data is written in the liquid crystal pixels. As soon as the writing is completed, the display state is maintained ( (Writing time (n) → display time (n)). Therefore, the screen display
It will always be rewritten from top to bottom of the screen, especially in fast-moving videos, it will be recognized so that the image of the previous field and the image of the next field overlap,
There is a problem that the user feels uncomfortable as if the image were being frame-advanced. Then, an object of the present invention is to solve the above-mentioned problems and to provide a liquid crystal display device excellent in moving image display capability.

[0008]

According to the present invention, there is provided a liquid crystal display device comprising: a liquid crystal display panel in which a plurality of liquid crystal pixels are arranged in a matrix; and a plurality of liquid crystal pixels connecting the plurality of liquid crystal pixels in a row direction and a column direction. A scanning driver that sequentially shifts and applies a predetermined scanning signal and scans the scanning line sequentially, a signal driver that applies an image signal to the signal line, and a back surface of the liquid crystal display panel. A liquid crystal comprising: a backlight that irradiates irradiation light from the side; an inverter circuit that drives the backlight by AC; and a drive control circuit that supplies control signals that control operations of the scan driver, the signal driver, and the inverter circuit. In the display device, the drive control circuit may include an image signal written to the liquid crystal display panel by the scan driver and the signal driver. , Characterized in that only a predetermined time within one field period for displaying lights the backlight.

According to a second aspect of the present invention, in the liquid crystal display device according to the first aspect, the predetermined time during which the image signal written on the liquid crystal display panel is displayed during the one field period. The time length and the timing are set to be uniform for all the scanning lines to be performed. The liquid crystal display device according to claim 3 is the liquid crystal display device according to claim 2,
The predetermined time for displaying the image signal written on the liquid crystal display panel is set to be equal to the lighting time of the backlight. Also,
5. The liquid crystal display device according to claim 4, wherein the drive control circuit comprises:
During a period other than the predetermined time in the field period, writing of all image signals for one screen is performed on the liquid crystal display panel.

Further, the liquid crystal display device according to claim 5 is
5. The liquid crystal display device according to claim 1, wherein the predetermined time for displaying an image signal written on the liquid crystal display panel is approximately one in one field period.
/ 3 or less. According to a sixth aspect of the present invention, in the liquid crystal display device according to any one of the first to fourth aspects, the predetermined time for displaying an image signal written on the liquid crystal display panel is:
It is characterized in that it is set to approximately 5 msec or less. The liquid crystal display device according to the seventh aspect is characterized in that:
In the liquid crystal display device according to any one of the above, the backlight emits irradiation light to the liquid crystal display panel based on the control signal supplied from the drive control circuit,
It is characterized by having a mechanism for switching and controlling the cutoff state.

That is, in the liquid crystal display device according to the present invention, the backlight is turned on to display data (image signal).
Is approximately one-third (approximately 5 mse) of one field period (1/60 sec = 16.6 msec).
c) Set the following, match the light emission permission time for all scan lines, match the light emission permission time with the backlight lighting time, and set one screen in a field period other than the light emission permission time. The display device further comprises a mechanism for writing display data for every minute to all the liquid crystal pixels and controlling a lighting state of the backlight. Therefore, in 2/3 of one field period, only display data is written to the liquid crystal pixels (display data writing operation), and the backlight remains off, and then the rest of the one field period In the time of 1/3 or less, the display data written with the backlight turned on is displayed (panel light emission display operation). By repeating the above display operation for each field, an intermittent (impulse type) display method is realized, and the moving image display capability can be improved.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the liquid crystal display device according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing one embodiment of a liquid crystal display device according to the present invention. 1, 10 is a liquid crystal display panel, 20 is a signal driver, 30 is a scan driver, 40 is an RGB decoder, 50 is an inverting amplifier, 60 is an LCD controller (drive control circuit), 70 is a common signal drive amplifier, 80
Denotes a backlight, 90 denotes an inverter circuit / backlight control circuit.

Each of the above structures is roughly as follows. The liquid crystal display panel 10 has pixel electrodes arranged in a matrix and a thin film transistor (hereinafter abbreviated as TFT) in which a source is connected to the pixel electrodes.
A scanning line extending in the row direction of the matrix and connected to the gates of the plurality of TFTs, and a signal line (also referred to as a source line) extending in the column direction of the matrix and connected to the sources of the plurality of TFTs. , A common electrode (also referred to as a counter electrode) to which a common signal Vcom described later is applied, and a liquid crystal filled between the pixel electrode and the common electrode. .

Each signal line is connected to the signal driver 20, and predetermined image data is stored in the signal driver 20 based on a horizontal control signal.
The data is stored in units of rows, and the corresponding video display signals are sequentially supplied to each signal line. Further, each scanning line is connected to the scanning driver 30, and a scanning signal is sequentially applied to the scanning line based on a vertical control signal to make a selected state, and a pixel electrode at a position intersecting with the signal line is connected to the signal line. Is applied. The RGB decoder 40 and the inverting amplifier 50 extract a vertical (V) and horizontal (H) clock signal and a synchronizing signal (CSY) from the video signal, supply them to an LCD controller 60 described later, and output the same from the LCD controller 60. Each of the red (R), green (G), and blue (B) color signals (hereinafter, referred to as RGB signals) included in the video signal is extracted based on the field / line inversion signal FRP to be generated, and, for example, each of the eight signals is extracted. The signal is converted into a digital RGB signal having a bit width, and an inverted RGB signal is supplied to the signal driver 20.

The LCD controller 60 is based on a horizontal clock signal (H), a vertical clock signal (V) and a synchronization signal (CSY) supplied from the RGB decoder 40.
The field / line inversion signal FRP is generated and output to the inversion amplifier 50, and the horizontal control signal and the vertical control signal are generated and supplied to the signal driver 20 and the scanning driver 30, so that the pixel is generated at a predetermined timing. Control is performed by applying a signal voltage to the electrodes and writing display data to the liquid crystal display panel 10. The common signal drive amplifier 70 generates a common signal Vcom for driving a common potential applied to the common electrode of the liquid crystal display panel 10 based on the field / line inversion signal FRP output from the LCD controller 60 described above. Output.

The backlight 80 is provided on the liquid crystal display panel 10.
A linear light source such as a cold cathode fluorescent lamp arranged along one end of a light guide plate (not shown) provided on the back side of
Based on the driving AC voltage supplied from 0, irradiation light of a predetermined luminance is emitted at a predetermined timing. The inverter circuit / backlight control circuit 90 controls the operation of the inverter circuit based on the backlight control signal generated and output by the LCD controller 50, and controls the lighting state of the backlight 80. Here, the backlight control signal output from the LCD controller 60 is generated as a signal synchronized with the display data write operation by the signal driver 20 and the scan driver 30 described above.
It is supplied to an inverter circuit / backlight control circuit 90. A specific control method will be described later.

Next, a specific operation of the liquid crystal display device according to the present embodiment will be described with reference to the drawings. FIG.
5 is a time chart illustrating an operation of the liquid crystal display device according to the present embodiment. (Display Data Writing Operation) First, all the display data for one screen is written to all the liquid crystal pixels during ２ of one field period (data writing allowable time). That is, as shown in FIG. 2, the uppermost scan line 1 of the liquid crystal display panel 10 is selected by the scan driver 30, and then predetermined display data is applied to the signal lines by the signal driver 20, thereby causing the first row to be displayed. Display data is written to each liquid crystal pixel. Hereinafter, the scanning lines 2, 3, 4,..., N are sequentially scanned and selected, and 2, 3, 4,.
Display data is written to each liquid crystal pixel in the row. Here, all the display data written during the data writing permissible time is held by the pixel capacitance constituting the liquid crystal pixel until one field period ends. Further, during the data writing allowable time, the backlight 80 is kept in an extinguished state or kept in a state where irradiation light is blocked.

(Panel light emission display operation) After the display data writing is completed within the data writing permissible time, the remaining one-third or less of the one-field period (light emission permissible time)
In the state where the display data written to all the liquid crystal pixels is held,
By setting 0 to the lighting state, light is emitted to emit light to perform light emission display. That is, in one field, the time length of the lighting time of the backlight 80 and the lighting timing are:
It is uniform for all scan lines. In this way, the image display based on the display data is instantaneously executed only for one third or less of one field period, and
Since the same display data writing operation and panel light emission display operation are repeated in the subsequent fields, intermittent image display is realized, and an afterimage effect equivalent to that of the impulse display method can be obtained. Therefore, as described in the related art, even when a moving image is displayed, the image of the previous field and the image of the next field do not overlap and are recognized, and the moving image display capability can be improved. it can.

Next, a description will be given of a data write allowable time defining a display data write operation and a light emission allowable time defining a panel light emitting display operation in this embodiment. As described above, in the present embodiment, 許 容 of a one-field period is set as the data writing allowable time, and １ ／ or less of the one-field period is set as the light emission allowable time. The case has been described. Each of these operation times is closely related to human vision as described above. That is, the response time of the human eye is generally said to be about 5 msec. Therefore, in the liquid crystal display device according to the related art, in order to realize a moving image display without a sense of discomfort, one field period is set to 5 msec (200 fsec).
ps). Therefore, in the present invention, by performing display data writing control and backlight lighting control, one field period is 1/60.
Time less than 1/3 of a second (about 16.6 msec) (approximately 5 msec)
The following) only turns on the backlight and emits display data, making use of the afterimage effect of human vision,
This realizes an impulse type display method.

In the liquid crystal display device according to the present embodiment, in order to realize the operation control as shown in FIG. 2, the structure of the backlight 80 is applied to, for example, a liquid crystal display device of a field sequential drive system. It is desirable to use one that is excellent in high-speed lighting and high-speed response. As another configuration, the backlight 8
It may be provided with a shutter mechanism or the like which can control the switching of the irradiation / blocking state of the irradiation light of 0 at a high speed of about 5 msec. In either configuration, in synchronization with the display data writing operation by the signal driver 20 and the scanning driver 30 controlled by the LCD controller 60, the time when two thirds of one field period has elapsed, or when all display data Is controlled by the backlight control circuit 90 so that the backlight 80 is switched to the lighting state from the time when writing to all the liquid crystal pixels is completed. In order to obtain the same display brightness as that of the conventional display method according to the present embodiment, it is necessary to increase the backlight brightness at least three times when the same liquid crystal display panel is used. It is necessary to increase the power supplied to the backlight three times or more. In order to shorten the display data writing period to 2/3 of one field period, it is necessary to increase the display data writing speed. However, all display data for one screen is temporarily stored. In addition, it is desirable to provide an image memory or the like for converting the frequency into a frequency corresponding to the write operation and supplying the converted signal to the signal driver 20.

[0021]

According to the invention as set forth in claim 1 or 4, in the liquid crystal display device, one-third of one field period (permissible data writing time) requires one liquid crystal display panel.
Only writing of all display data for the screen is performed, and then, during the remaining one-third or less of the one-field period (light emission permission time), only the light emission display of the written display data with the backlight turned on is performed. Thereby, an impulse-type display method is realized also in the liquid crystal display, so that the moving image display capability can be improved. Claim 2
According to the invention described in the third aspect, the emission permission time for displaying the image signal written on the liquid crystal display panel is set to a uniform time length and timing for all the scanning lines scanned in one field period, and By setting the backlight so as to coincide with the lighting time of the backlight, all display data can be simultaneously displayed by light emission, so that an intermittent short-time display can be continuously realized as in the case of display on a movie film. . Therefore, the moving image display capability can be further improved as compared with a CRT that performs scanning display using an electron gun.

According to the fifth or sixth aspect of the present invention, the light emission permission time for performing the light emission display of the display data written in the liquid crystal display panel with the backlight turned on is approximately one third or less of one field period. Alternatively, by setting the time to about 5 msec or less, the afterimage effect of human vision can be used, so that the conventional liquid crystal display can prevent a sense of discomfort such as an image being frame-advanced, and The display ability can be improved. And Claim 7
According to the described invention, the configuration of the backlight is LC
By providing a mechanism for switching the irradiation of the liquid crystal display panel and the cutoff state at high speed based on the backlight control signal supplied from the D controller,
Since the light emission display of the display data can be realized corresponding to the light emission permission time of about 1/3 or less of the field period or about 5 msec or less, the impulse type display method can be favorably realized.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a liquid crystal display device according to the present invention.

FIG. 2 is a time chart illustrating an operation of the liquid crystal display device according to the embodiment.

FIG. 3 is a diagram illustrating a relationship between a moving image display capability and a display method.

FIG. 4 is a time chart illustrating an operation of the liquid crystal display device according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Liquid crystal display panel 20 Signal driver 30 Scan driver 40 RGB decoder 50 Inverting amplifier 60 LCD controller 70 Common signal drive amplifier 80 Backlight 90 Inverter circuit / backlight control circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 2H093 NA16 NC34 NC44 ND58 ND60 NH00 5C006 AA01 AA22 AF03 AF04 AF42 AF44 AF51 AF71 BB16 BB29 BF25 BF26 EA01 FA21 FA34 5C080 AA10 BB05 CC03 DD05 DD06 EE19 FF11 JJ02 JJ04JJ04

Claims (7)

[Claims] 1. A liquid crystal display panel in which a plurality of liquid crystal pixels are arranged in a matrix, a plurality of scanning lines and signal lines connecting the plurality of liquid crystal pixels in a row direction and a column direction, and a predetermined scanning signal are sequentially transmitted. A scan driver that shifts and applies, sequentially scans the scan line, a signal driver that applies an image signal to the signal line, and a backlight that irradiates irradiation light from the back side of the liquid crystal display panel,
A liquid crystal display device comprising: an inverter circuit for AC driving the backlight; and a drive control circuit for supplying a control signal for controlling operations of the scan driver, the signal driver, and the inverter circuit. A liquid crystal display device wherein an image signal written to the liquid crystal display panel by a scanning driver and a signal driver is displayed by lighting the backlight only for a predetermined time within one field period. 2. The predetermined time for displaying an image signal written on the liquid crystal display panel is set to a uniform time length and a uniform timing for all the scanning lines scanned in the one field period. The liquid crystal display device according to claim 1, wherein: 3. The liquid crystal according to claim 2, wherein the predetermined time for displaying the image signal written on the liquid crystal display panel is set so as to coincide with a lighting time of the backlight. Display device. 4. The drive control circuit writes all image signals for one screen to the liquid crystal display panel during a period other than the predetermined time in the one field period. 3. The liquid crystal display device according to 3. 5. The liquid crystal display panel according to claim 1, wherein the predetermined time for displaying an image signal written on the liquid crystal display panel is set to be approximately one third or less of the one field period. The liquid crystal display device according to any one of the above. 6. The liquid crystal display according to claim 1, wherein the predetermined time for displaying the image signal written on the liquid crystal display panel is set to approximately 5 msec or less. apparatus. 7. The backlight according to claim 1, wherein the backlight has a mechanism for switching between irradiating light and irradiating the liquid crystal display panel based on the control signal supplied from the drive control circuit. The liquid crystal display device according to any one of claims 1 to 6, wherein: