JPH0973061A - Liquid crystal display device and driving method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device capable of displaying a video with different scanning lines and a driving method therefor, to a full line liquid crystal display device driven in an interlace system. SOLUTION: A liquid crystal display device 1 is constituted of an input terminal 2 for a video signal, a decoder 3 decoding the signal into a separate signal, a signal driver 4 to convert the video signal into AC signal, a timing signal generator TG5 to supply various kinds of control signals, and a liquid crystal panel 10. The liquid crystal panel 10 is interpolated with H-scanner 11 and V-scanner 12. For example, if V-scanner 12 thins out No.5 in an odd numbered field, then its neighboring number No. 4 or No. 6 is surely thinned out in the even numbered field. This enables a video signal displayed on a liquid crystal display 1 to be prevented from a reverse phenomenon and also prevented from deterioration of vertical resolution.

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 used in, for example, a VTR with a built-in camera, a liquid crystal projector, and the like, and a driving method thereof. The present invention relates to a liquid crystal display device and a driving method thereof.

[0002]

2. Description of the Related Art In recent years, with the spread of equipment with a liquid crystal display device represented by a VTR with a built-in camera and a liquid crystal projector, the demand for higher performance of the liquid crystal display device has increased, and the performance of the liquid crystal display device has rapidly increased. are doing. Under such circumstances, improvements have been made to add new functions to liquid crystal display devices, and compatible liquid crystal display devices have been developed and commercialized. For example, NTSC system and PAL (Phase Alter)
Nationby Line) compatible models have also been commercialized. When trying to display NTSC and PAL images on the same liquid crystal display device, NTSC
The number of effective scanning lines in the PAL method is approximately 575, whereas the number of effective scanning lines in the PAL method is approximately 575, and it is general that the scanning lines lacking in the PAL method are thinned and displayed at regular intervals.

On the other hand, in the liquid crystal display device, a so-called full line liquid crystal display device having approximately 480 effective scanning lines has been developed with the progress of higher resolution mainly in large liquid crystal display devices and liquid crystal display devices for liquid crystal projectors. I have put it out. Two typical methods are known as methods for displaying an image on such a full-line liquid crystal display device. As one of them, there is a double-speed drive method in which a frame memory or other means generates a double-speed video signal and operates a time axis to convert the frame frequency into a frequency range where flicker does not occur. That is, in principle, the liquid crystal display device is driven by alternating current, and the full line liquid crystal display device described above has approximately 4 effective scanning lines.
This is because, since 80 lines are provided, it is necessary to generate scan line segments lacking in interlaced scanning (hereinafter simply referred to as “interlace”) and perform AC driving. However, in order to realize this double speed drive system, it is necessary to add hardware such as an A / D converter, a frame memory, and a D / A converter.

As the second, when writing the video signal for one scanning line, the scanning lines for two lines before and after are simultaneously selected and the video signal is written, and the combination of the two lines is changed for each field to obtain the vertical resolution. There is a so-called line pair drive system that prevents deterioration. However, in this line pair driving method, when driving a liquid crystal display device of delta arrangement in particular, even though the video signals written simultaneously are the same signals in the horizontal direction, the actually displayed dot position is There is a problem that the horizontal resolution is deteriorated by being shifted by 0.5 dot.

In order to solve these problems, attempts are being made to drive a full-line liquid crystal display device by an interlace system similar to a general cathode ray tube (CRT) display method. That is, in the liquid crystal display device, an odd field video signal is applied to the odd scan lines and an even field video signal is applied to the even scan lines to display the composite video as a frame.

[0006]

However, when it is attempted to display images of different scanning lines with compatibility on a full line liquid crystal display device driven by an interlace method, a simple thinning method is preferable. It is not possible to display such images. That is, for example, when an image of the PAL system having 575 scanning lines is displayed on a liquid crystal display device having 480 scanning lines driven by the interlace system, if the thinning driving is performed by the simple thinning system, scanning of odd fields is performed. There is a problem in that the lines and the scanning lines in the even field are reversed and the correlation cannot be obtained, resulting in a significant deterioration of the vertical resolution.

The present invention has been made in consideration of the above points, and causes deterioration of vertical resolution when an interlaced full-line liquid crystal display device is driven while being compatible with images having different scanning lines. Provided is a liquid crystal display device which is improved and displays with excellent image quality, and a driving method thereof.

[0008]

In order to solve the above problems, a liquid crystal display device for driving a full line liquid crystal display device of the present invention by an interlaced thinning method generates a control signal, an inversion control signal and an enable signal. A timing generator, a horizontal drive circuit to which signal lines are connected, and a vertical drive circuit to which scanning lines are connected and which receives various control signals to newly generate skipping or scanning selection pulses including thinning information. , And a pixel formed at the intersection of the signal line and the scanning line. The vertical drive circuit is preferably composed of a D-type flip-flop circuit, an input terminal for inputting various control signals, and an AND circuit.
It is assumed that an enable signal and the output of the adjacent D-type flip-flop circuit are connected to the circuit.

In a driving method of a liquid crystal display device for driving a full-line liquid crystal display device having such components by an interlaced thinning method, a scanning line adjacent between fields is determined based on thinning information generated by a vertical driving circuit. It was decided to thin out at the same time to prevent deterioration of vertical resolution.

In the liquid crystal display device and the driving method thereof according to the present invention, adjacent scanning lines between fields are simultaneously thinned based on a new selection pulse generated by a vertical driving circuit, or scanning lines of only a single field. By not thinning out, the inversion phenomenon of the video signal between fields was prevented. Therefore, it is possible to prevent deterioration of the vertical resolution of the display image.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a liquid crystal display device and a driving method thereof according to the present invention will be described below with reference to FIGS. First, the configuration of the liquid crystal display device of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing the configuration of the liquid crystal display device of the present invention.

In FIG. 1, reference numeral 1 indicates the liquid crystal display device of the present invention. The liquid crystal display device 1 of the present invention is based on an input terminal 2 to which a video signal such as a composite video is input, a decoder 3 for converting the input video signal into separate signals of R, G and B, and an inversion control signal FRP described later. Signal driver 4 for converting video signals into alternating current, HST and HC required for control
A timing generator that supplies control signals such as K, VST, VCK1 and VCK2, and enable signals (hereinafter simply referred to as “ENB”) to the liquid crystal panel at the next stage, and also supplies the inverted control signal FRP to the signal driver 4 (hereinafter referred to as “timing generator”). , And simply referred to as "TG") 5, and a liquid crystal panel 10 for displaying images in color or monochrome.

The detailed configuration of the liquid crystal panel 10 is configured by inserting an H scanner 11 as a horizontal drive circuit including an H shift register and a sample hold, and a V scanner 12 as a vertical drive circuit including a V shift register and a buffer. It A control signal for the H scanner such as HST and HCK is input to the H scanner 11, and a switching circuit 13 is connected. Video signals of R, G, B, etc. are input to the switching circuit 13, and a signal line 14 is connected. The V scanner 12, which is a feature of the present invention, includes VST, VCK1, VCK2 and EN.
A control signal for V scanner such as B is input,
A scanning line (hereinafter, also referred to as “line”) 15 in the row direction is connected. Further, the V scanner 12 is provided with a shift register whose circuit example is shown in FIG. 2, which will be described later, so that a predetermined scanning line can be selected.

The signal lines 14 and the scanning lines 15 are arranged in a matrix, and thin film transistors (Thi
n Film Transistor: hereinafter simply referred to as "TFT") 16
Are arranged. A common electrode 17 is formed on the TFT 16 via the storage capacitor Cs and the liquid crystal cell LC. In this example, the arrangement of the TFTs 16 is illustrated as a square arrangement, but the present invention can be applied to a delta liquid crystal display device mainly used for AV equipment and is not limited to a pixel arrangement.

The operation of the liquid crystal display device of the present invention having such a configuration will be described. A video signal such as a composite video input to the input terminal 2 in FIG. 1 is input to the decoder 3. The decoder 3 converts the video signal into R, G, and B separate signals suitable for driving the liquid crystal panel 10 and adds an adjusting circuit (not shown) such as color, picture, and hue (hue) to the next stage. It is sent to the signal driver 4. The signal driver 4 amplifies the gain of the video signal, converts it into an alternating current based on the inversion control signal FRP, and outputs it.

In the TG 5, a control signal used for controlling the liquid crystal panel 10 is supplied to a VCO (Voltage-Controlled Oscill).
ator: not shown), or generated from H-Syncn and V-Sync synchronization signals and output to the signal driver 4 and the liquid crystal panel 10. The control signals are specifically HST, HCK, VS
T, VCK1, VCK2, ENB, etc. To briefly explain the operation of these control signals, HST is a start pulse for the shift register of the H scanner 11, HCK is a clock pulse for the shift register of the H scanner 11, and VST is a pulse pulse of the V scanner 12. This is the start pulse for the shift register, and VCK1 is V
It is a clock pulse for the scanner 12, and VCK2 is V
This is a clock pulse having a phase opposite to that of CK1. The ENB is connected to the V scanner 12 so that a predetermined scanning line of the V scanner 12 can be selected. That is, it is used for thinning out as a "low level" when displaying images of different scanning lines, for example, NTSC or PAL system.

In the liquid crystal panel 10, the signal driver 4
Video signals such as R, G, B, etc., input from HST, H
It receives control signals such as CK, VST, VCK1, VCK2, and ENB, and supplies them to the H scanner 11 and V scanner 12. In the TFT 16, the scanning line 15 is selected in response to the selection pulse generated from the V scanner 12, and H
A video signal is fetched from the signal line 14 via the switching circuit 13 connected to the scanner 11. The captured video signal is supplied to the storage capacitor CS and the liquid crystal cell LC. In the liquid crystal cell LC, the liquid crystal molecules are twisted in the direction of the applied voltage and inverted by the image voltage supplied according to the image level of each pixel, and the liquid crystal molecules and the polarizing plate (neither is shown).
An image is displayed on the liquid crystal panel 10 by utilizing the optical rotatory power.

Next, the structure of the V scanner of the liquid crystal display device of the present invention will be described with reference to FIG. FIG. 2 is a circuit diagram showing an example of the V scanner of the present invention.

The V scanner of the present invention is a D-type flip-flop 1 using a clocked inverter (inverting amplifier).
8, the D-type flip-flop 18 is, for example, direct current 15.5V
Is connected to the power supply VCC, and one end thereof is connected to the ground terminal GND. VCK1 at the input terminal,
VCK2, VST, and ENB are input. Further, an AND circuit 1 is provided at the final stage of the V scanner.
9 is provided, and the AND circuit 19 is configured by connecting ENB and the output of the adjacent D-type flip-flop 18.

The operation of the V scanner of the present invention having such a configuration will be described. The V scanner has VCK1 from the input terminal,
The control signals of VCK2, VST, and ENB are received, and the output signals A1 and A which are selection pulses of each line are activated by operating the D-type flip-flop 18.
2, A3 ... Is output. Output signals A1, A2, A3
The adjacent output of EN and ENB are input to the AND circuit 19. In the AND circuit 19, a new gate pulse (scanning line selection pulse) G1, G2, G3, G4 for driving the liquid crystal display device of the present invention is obtained by ANDing the output of the adjacent D flip-flop 18 and the ENB signal. Output as from V scanner. This selection pulse G1, G2, G
When G3, ... Are at "high level", the line becomes active (selected state). Specific examples of these timing operations will be described below.

A specific example of the liquid crystal display device and the driving method thereof according to the present invention will be described with reference to FIG. FIG. 3 is a timing chart showing the operation of the liquid crystal display device of the present invention.

The video signal in FIG. 3 is a signal input every horizontal period in response to the selection pulse of each line, and the added numbers 2, 4, 6, 8, 10, 12 ... This means that the signal is, for example, an even field interlace. By operating the aforementioned V scanner, the output signals A1, A2, A3, A4 ... Are outputted as new selection pulses G1, G2, G3, G4.
Here, the number added to the new selection pulse corresponds to the number of the input video signal, and it can be seen that when driven in this manner, the input video signal No. 6 is thinned out.

To explain the operation of the V scanner of the present invention in detail, the V scanner starts its operation with VST as a start reference, and the timing pulse VCK1 outputs a pulse every horizontal blanking period. And V
A1, which sets the rising period of CK1 to "high level",
.. and A2, A4, A6 ... Which make the falling period of VCK “high level” are output. Further, when the ENB for setting the horizontal blanking period or the desired thinning period to "low level" is input, the V scanner operates as follows for each field.

First, for example, G3 in an odd field
Is generated from the AND circuit of A2, A3 and ENB, so that a new selection pulse is not output. As a result, the selection pulse is not output on the odd lines of G1, G3, ...

Next, for example, G2 in the even field
Is generated from the AND circuit of A1, A2 and ENB, so the G2 pulse with the second addition is output,
As a result, a selection pulse is output on the even-numbered lines of G2, G4, ..., In response to this selection pulse, video signals are sequentially taken in from the H scanner and the video is displayed on each pixel. Further, for example, in G5, which corresponds to the thinning line, A4, A
Since it is generated from the AND circuit of 5 and ENB, a new selection pulse is not output, and as a result, the video signal No. 6 on G5 is thinned out and not displayed on the liquid crystal panel.

Next, with reference to FIG. 4, a method of thinning out video signals within a frame in the liquid crystal display device of the present invention will be described. 4A and 4B are explanatory views showing a thinning method of the liquid crystal display device of the present invention, FIG. 4A shows a state in which only odd fields are thinned, and FIG. 4B shows a state in which both fields are optimized and thinned. Is.

In the liquid crystal display device driven by the interlace system shown in FIG. 4A, it is assumed that the fifth video image in the odd field is thinned out. At this time, if the 4th image or the 6th image in the even field is not thinned out, the image displayed on the 5th line of the liquid crystal display device is the 7th image and the image displayed on the 6th line is the 6th image. Become. In this way, the images on the 5th and 6th lines and the following display lines are displayed in reverse, resulting in a significant deterioration of the vertical resolution.

On the other hand, as a characteristic feature of the driving method of the liquid crystal display device of the present invention, the thinning method is optimized by the following method. That is, in FIG. 7B, for example, when the fifth video image in the odd field is thinned out, the fourth video image or the sixth video image (the sixth video image in this example) adjacent to the fifth video image is always thinned in the even field. did. This makes it possible to prevent the inversion phenomenon of the video signal displayed on the liquid crystal display device, and prevent the vertical resolution from deteriorating.

The present invention is not limited to the above-described embodiment, but can adopt various embodiments. For example, in the present embodiment, the case where the H scanner and the V scanner are interpolated has been illustrated, but the same can be applied to the case where the H scanner and the V scanner are extrapolated. Further, it is needless to say that the present invention is not limited to the liquid crystal mode and the addressing method and can be applied to a large screen liquid crystal display device and other display devices.

[0030]

As described above, according to the liquid crystal display device and the driving method thereof of the present invention, the full line liquid crystal display device is driven by the interlace system, and the thinning driving is performed by the optimized thinning method. As a result, it is possible to reduce the circuit for non-interlace conversion and the circuit for scanning line conversion, and a low-cost liquid crystal display device can be realized. In addition, in the full line liquid crystal display device driven by the interlace system,
It is possible to improve the deterioration of the vertical resolution that occurs when driving images of different scanning lines with compatibility, and display an interlaced image with a natural image quality.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a liquid crystal display device of the present invention.

FIG. 2 is a circuit diagram showing an example of a V scanner of the present invention.

FIG. 3 is a timing chart showing the operation of the liquid crystal display device of the present invention.

4A and 4B are explanatory views showing a thinning-out method of the liquid crystal display device of the present invention, FIG. 4A shows a state in which only odd fields are thinned out, and FIG. 4B shows a state in which both fields are optimized and thinned out. It is a figure.

[Explanation of symbols]

 1 Liquid Crystal Display Device of the Present Invention 2 Input Terminal 3 Decoder 4 Signal Driver 5 Timing Generator TG 10 Liquid Crystal Panel 11 H Scanner 12 V Scanner 13 Switching Circuit 14 Signal Line 15 Scanning Line (Line) 16 TFT 17 Common Electrode (COM Electrode) 18 D flip-flop 19 AND circuit

Claims (4)

[Claims] 1. A liquid crystal display device for driving a full-line liquid crystal display device by an interlaced thinning method, wherein a timing generator for generating a control signal, an inversion control signal and an enable signal, and a horizontal drive circuit to which a signal line is connected. A vertical drive circuit connected to a scanning line and receiving the control signal, the inverted control signal and the enable signal, and newly generating an interlacing or scanning selection pulse including thinning information; And a pixel formed at the intersection of the scanning lines. 2. The vertical drive circuit includes a D-type flip-flop circuit, an input terminal for inputting various control signals, and an AND.
2. The liquid crystal display device according to claim 1, wherein the liquid crystal display device comprises a circuit, and the AND signal is connected to the enable signal and the output of the adjacent D-type flip-flop circuit. 3. A driving method of a liquid crystal display device for driving a full line liquid crystal display device by an interlace thinning method, wherein a timing generator for generating a control signal, an inversion control signal and an enable signal is connected to a signal line. A horizontal drive circuit; and a vertical drive circuit which is connected to a scanning line and which receives the control signal, the inverted control signal and the enable signal, and newly generates a skip or scan selection pulse including thinning information, Degradation of the vertical resolution by simultaneously thinning adjacent scanning lines between fields based on the thinning information generated by the vertical driving circuit, the pixel including pixels formed at intersections of the signal lines and the scanning lines. A method for driving a liquid crystal display device, comprising: 4. The method for driving a liquid crystal display device according to claim 3, wherein the relationship between the selection pulses for the interlacing and scanning is switched for each field.