JP3318819B2 - Liquid crystal drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal driving device used for, for example, a liquid crystal projector, and more particularly, to a method for writing a video signal to a liquid crystal display panel.
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal drive device that automatically adjusts a write video signal to achieve uniform display.

[0002]

2. Description of the Related Art In recent years, with the spread of devices equipped with a liquid crystal display panel represented by a liquid crystal projector, demands for higher performance of the liquid crystal display panel have increased, and the resolution and image quality of the liquid crystal display panel have increased. I have. 2. Description of the Related Art In a liquid crystal projector, an image is displayed by projecting light transmitted through a liquid crystal display panel onto a screen. Illumination light is formed by a light source such as a metal halide lamp. Decomposes into light. Further, this type of projector drives a liquid crystal display panel corresponding to red, green and blue color signals, and transmits red, green and blue illumination light to each liquid crystal display panel. After the transmitted lights of these liquid crystal display panels are combined, they are magnified several tens to hundreds times by a projection lens and projected on a screen to form a color display image.

On the other hand, in a liquid crystal display panel, the number of pixels increases as the resolution of the liquid crystal display panel increases, and the frequency characteristics required of a control circuit for writing a video signal to the liquid crystal display panel are becoming severer. . For this reason, a method of preliminarily dividing a signal line into several lines and simultaneously writing them all at once, for example, a method of alleviating required frequency characteristics is adopted as a simultaneous sampling method of three dots.

[0004]

By the way, a uniform display quality is required for a liquid crystal display panel corresponding to each color applied to this type of projector. In particular, in a high-resolution liquid crystal display panel driven by the above-described multiple simultaneous sampling method, uniformity of a written video signal of each channel is required. For example, when driving a plurality of liquid crystal display panels for red by the simultaneous sampling method, if the written video signal of each channel varies, the density of the liquid crystal display panel becomes uneven, and not only the liquid crystal display panel for red but also the entire projector apparatus This is because there is a possibility that the display quality may be deteriorated. In general, an analog processing circuit is used for the control circuit of these liquid crystal display panels, and the characteristics of each channel, such as gain (gain) and luminance (brightness), must be strictly adjusted with an adjustment volume or the like. In addition, there is a problem in that display quality is deteriorated due to variations at the time of adjustment and variations due to factors after the adjustment unit. In addition, there is a problem that each channel of the analog processing circuit must be uniformly adjusted, and it takes time to adjust.

The present invention has been made in view of the above points, and in a high-resolution and high-speed liquid crystal display panel, the display unevenness of the liquid crystal display panel due to a variation in adjustment of a processing circuit is eliminated to improve display quality. The present invention provides a liquid crystal drive device that achieves the above.

[0006]

According to a first aspect of the present invention, there is provided a liquid crystal driving apparatus for simultaneously sampling and driving a plurality of channels when writing a video signal to a liquid crystal display panel. A reference channel processing circuit that supplies a reference video signal, and one or more comparison channel processing circuits, and a white level insertion circuit that inserts a white level into an input video signal and a black level insertion that inserts a black level It has a circuit. The reference channel processing circuit includes a sample-and-hold circuit for sampling a video signal having a white level and a black level inserted therein, an inverting / non-inverting amplifying circuit for dividing the video signal into inverted / non-inverted and amplifying the same, and adjusting the same. Inverting / non-inverting gain adjusting means, inverting / non-inverting luminance adjusting circuit for adjusting the luminance of the inverting / non-inverting video signal, inverting / non-inverting luminance adjusting means for adjusting the same, and inverting / non-inverting video. A switch circuit for switching signals, a buffer circuit, an output unit to a liquid crystal display panel, and an inverted / non-inverted white level detector that outputs a white level of an inverted / non-inverted video signal to a comparison channel processing circuit as a reference white level. , And an inverted / non-inverted black level detector that outputs the black level as a reference black level to the comparison channel processing circuit.

Further, the comparison channel processing circuit performs a sample-and-hold circuit, an inverting / non-inverting amplifying circuit that divides and amplifies a video signal by inversion / non-inversion, and adjusts the brightness of the inverted / non-inverted video signal. An inversion / non-inversion luminance adjustment circuit;
A switch circuit for switching, a buffer circuit, an output unit to a liquid crystal display panel, and a white level of an inverted / non-inverted video signal are detected and compared with a reference white level for inversion /
Gain feedback means for controlling the non-inverting amplifier circuit; detecting a black level;
Brightness feedback means for controlling the non-inverted brightness adjustment circuit. Then, the gain feedback means and the luminance feedback means automatically control the gain and brightness of the comparison channel processing circuit so as to match the reference channel processing circuit.

According to a second aspect of the present invention, there is provided a liquid crystal driving apparatus for simultaneously sampling and driving a plurality of channels when writing a video signal to a liquid crystal display panel.
It comprises a reference channel processing circuit and one or more comparison channel processing circuits, and has an intermediate level insertion circuit for inserting an intermediate level between a white level and a black level into an input video signal. The reference channel processing circuit includes a sample and hold circuit that samples a video signal having an intermediate level inserted, an inversion / non-inversion amplification circuit that divides the video signal into inversion / non-inversion and amplifies the same, and an inversion / non-inversion amplification. Inverting / non-inverting gain adjusting means connected to the circuit and the comparison channel processing circuit, an inverting / non-inverting luminance adjusting circuit for adjusting the luminance of the inverting / non-inverting video signal, and an inverting / non-inverting luminance for adjusting the same. Adjusting means, a switch circuit for switching, a buffer circuit, an output unit to the liquid crystal display panel, and an inverted / non-inverted intermediate for outputting to the comparison channel processing circuit an intermediate level of the inverted / non-inverted video signal as a reference intermediate level And a level detector.

Further, the comparison channel processing circuit includes:
A sample-and-hold circuit, an inversion / non-inversion amplification circuit to which an image signal is divided and inverted / non-inverted and amplified by an inversion / non-inversion gain adjustment means, and a luminance adjustment of the inversion / non-inversion image signal; An inversion / non-inversion brightness adjustment circuit to perform;
A switch circuit for switching, a buffer circuit, an output unit to a liquid crystal display panel, and a luminance for detecting an intermediate level of an inverted / non-inverted video signal and controlling the inverted / non-inverted amplifier circuit by comparing with a reference intermediate level. Return means. Then, the brightness feedback means automatically controls the brightness of the comparison channel processing circuit so as to match the brightness of the reference channel processing circuit.

The liquid crystal driving device according to the first aspect of the present invention includes a reference channel processing circuit for supplying a reference video signal to the liquid crystal display panel, and a comparison channel processing circuit. A reference video level is obtained by inserting a white level or a black level. The reference video level is sent to the comparison channel processing circuit, which detects its own video level and compares it with the reference video level to feed back to its own video level control circuit. Then, the video signal of the comparison channel processing circuit is aligned with the video signal of the reference channel processing circuit. Thus, in a method of driving a liquid crystal display panel by simultaneously sampling a plurality of pixels, it is possible to improve display unevenness caused by variations in each channel processing circuit.

According to the second aspect of the present invention, an intermediate level between a white level and a black level is inserted into an input video signal, and a reference video level is obtained based on the intermediate level. The reference video level is sent to a comparison channel processing circuit, which detects its own video level, compares it with the reference video level and feeds back to its own video level control circuit to provide a comparison channel. The video signal of the processing circuit is aligned with the video signal of the reference channel processing circuit. Thereby, the circuit scale of the processing circuit can be simplified, and display unevenness can be improved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the code | symbol attached to a component is described in the vicinity of the component, and the leader line was omitted. The components are partially “S / H” “AM”
P "," SW "," BUFF. "

First Embodiment Referring to FIGS. 1 to 4, a first embodiment of a liquid crystal driving device according to the present invention will be described.
The embodiment will be described in detail. First, FIGS. 1 to 3
The configuration of the first embodiment will be described with reference to FIG. FIG. 1 is a diagram showing a first embodiment of a liquid crystal driving device according to the present invention, and is a block diagram showing a first channel, and FIG.
FIG. 3 is a block diagram showing a channel, and FIG. 3 is a block diagram showing a third channel.

In FIG. 1, reference numeral 1 indicates a liquid crystal driving device of the present invention. The liquid crystal driving device 1 of the present invention is configured to include one reference channel processing circuit and two comparison channel processing circuits. The first as a comparison channel processing circuit
The channel is an example in which a predetermined color signal is divided into three and input to a signal line. For example, an input unit 2 to which a red video signal is input, a white level insertion circuit 3 for adding a white level to the input video signal, an input A black level insertion circuit 4 for adding a black level to a video signal; a first sample and hold circuit 5 to which a white level / black level insertion video signal A is input; a common sample and hold circuit 6 for latching; Amplifying circuit 8, comparators 9, 10, 15, 16, inverting brightness adjusting circuit 11, non-inverting bright adjusting circuit 12, switch 13,
It comprises a buffer circuit 14 and an output unit 21 for outputting a video signal to the liquid crystal display panel. Further, an inverted white level detector 17 connected to the buffer circuit 14 for detecting the white level of the inverted video signal, an inverted black level detector 18 for detecting the black level, and a white level of the non-inverted video signal. It comprises a non-inverted white level detector 19, a non-inverted black level detector 20 for detecting a black level, and the like.

The output of the inverted white level detector 17 is connected to one end of the comparator 9, and the output of the comparator 9 is connected to the control terminal 7a of the inverting amplifier circuit 7 to form gain feedback means. The output of the inverted black level detector 18 is connected to one end of the comparator 10, and the output of the comparator 10 is connected to the control terminal 11a of the inverted brightness adjustment circuit 11 to form a luminance (hereinafter, also referred to as "bright") feedback means. ing. The output of the non-inverted white level detector 19 is connected to one end of a comparator 16, the output of which is connected to the control terminal 8a of the non-inverted amplifier circuit 8, and the output of the non-inverted black level detector 20 is connected to one end of the comparator 15. And its output is connected to a control terminal 12a of the non-inverted bright adjustment circuit 12.

In FIG. 2, a second channel serving as a reference channel processing circuit includes a second sample-and-hold circuit 22 to which the above-described white level / black level insertion video signal A is input,
A common sample-and-hold circuit 6, an inverted brightness adjusting means 23 for adjusting the brightness as a reference for the inverted video signal, an inverted gain adjusting means 24 for adjusting the gain, and a non-inverted gain adjusting means 24 for adjusting the gain as the reference for the non-inverted video signal. Inverting gain adjusting means 25, non-inverting bright adjusting means 26 for similarly adjusting brightness, inverting amplifier circuit 27, non-inverting amplifier circuit 28,
Inverted brightness adjustment circuit 29, non-inverted brightness adjustment circuit 3
0, a switch 31, a buffer circuit 32, and an output unit 37 for outputting a video signal to the liquid crystal display panel. Further, the inverted white level detector 33 is connected to the buffer circuit 32 and detects a white level from the inverted video signal and outputs it as an inverted white level B. The inverted black level detector 34 outputs an inverted black level C. It comprises a non-inverted white level detector 35 that outputs a non-inverted white level D, an inverted black level detector 36 that outputs a non-inverted black level E, and the like.

In FIG. 3, a third channel serving as a comparison channel processing circuit includes a third sample / hold circuit 38 to which a white level / black level insertion video signal A is input, a common sample / hold circuit 6, an inverting amplifier circuit 39, It comprises an inverting amplifier circuit 40, comparators 41, 42, 47, 48, an inverting brightness adjusting circuit 43, a non-inverting brightness adjusting circuit 44, a switch 45, a buffer circuit 46, and an output unit 53 for outputting a video signal to a liquid crystal display panel. Is done. Further, the inverted white level detector 49 is connected to the buffer circuit 46 and detects an inverted white level from the inverted video signal, and the inverted black level detector 5 detects an inverted black level.
0, non-inverted white level detector 5 for detecting non-inverted white level
1. Inverted black level detector 52 for detecting non-inverted black level
And so on.

The output of the inverted white level detector 49 is connected to one end of the comparator 41, and the output of the comparator 41 is connected to the control terminal 39a of the inverting amplifier 39 to form gain feedback means. The output of the inverted black level detector 50 is connected to one end of the comparator 42, and the output of the comparator 42 is connected to the control terminal 43a of the inverted brightness adjustment circuit 43 to form a luminance feedback means. The output of the non-inverting white level detector 51 is connected to one end of a comparator 48, the output of which is connected to the control terminal 40a of the non-inverting amplifier circuit 40, and the output of the non-inverting black level detector 52 is connected to one end of a comparator 47. The output is connected to a control terminal 44a of a non-inverted bright adjustment circuit 44.

The operation of the liquid crystal driving device of the present invention having such a configuration will be described. For example, a red video signal input to the input unit 2 in FIG. 1 is input to a white level insertion circuit 3. The white level insertion circuit 3 generates a predetermined white level W as preprocessing of the liquid crystal driving device of the present invention and inserts it into an input video signal. The black level insertion circuit 4 normally uses the pedestal level of the video signal as the black level, but if necessary, generates the black level P and inserts it into the input video signal. In addition,
These level signals of the white level W and the black level P are inserted during a blanking period that does not interfere with the video signal.
Then, a white level / black level inserted video signal A into which the white level W and the black level P are inserted is supplied to each channel.

Turning to FIG. 2, the operation of the second channel as a reference channel processing circuit will be described. The second sample-and-hold circuit 22 performs a sub-sampling process for dividing the video signal for the second channel. The sub-sampled video signal is latched by the common sample-and-hold circuit 6 (resampling of a phase transition point). These processes are performed by receiving a pulse from a timing generator (not shown). The latched video signal is divided into inverted / non-inverted signals and input to the inverted amplifier circuit 27 and the non-inverted amplifier circuit 28, respectively. The inverting amplifier 27 and the non-inverting amplifier 28 have a control terminal 27
The inverting gain adjusting means 24 and the non-inverting gain adjusting means 25 are connected via a and 28a, and by adjusting these adjusting means, the gain of the inverting / non-inverting video signal serving as a reference is adjusted. . Inverted brightness adjustment circuit 2
9 and the non-inverted brightness adjustment circuit 30
The inverted brightness adjusting means 23 and the non-inverted brightness adjusting means 26 are connected via the terminals a and 30a. By adjusting these adjusting means, the brightness of the inversion / non-inversion video signal serving as a reference is adjusted. You.

The inverted / non-inverted video signal is input to a switch 31 and alternately switched by the switch 31 to become an AC-converted video signal suitable for a liquid crystal display panel. The AC-converted video signal is output to the liquid crystal display panel via a buffer circuit 32 including a current amplifier for driving a load. On the other hand, the video signal output from the buffer circuit 32 is input to an inverted white level detector 33, an inverted black level detector 34, a non-inverted white level detector 35, and a non-inverted black level detector 36, respectively. These detectors detect a black level and a white level of an inverted / non-inverted video signal described later.

Here, the detailed configuration of the inverted / non-inverted video signal will be described with reference to FIG. FIG. 4 is a waveform diagram showing inverted / non-inverted video signals of the liquid crystal driving device of the present invention.

In FIG. 4, the video signal is alternately switched by a switch, and becomes an alternating video signal suitable for a liquid crystal display panel. In this case, the alternating voltage is set with the illustrated common voltage K as a substantially symmetrical point. When the white level W and the black level P are detected from the video signal, the white level W and the black level P of the inverted / non-inverted video signal are inserted in a part of the video signal in advance by an insertion circuit. The sample level is held at the timing of the white level W and the black level P, so that the white level W and the black level P can be detected. In the same figure, adjusting the gain means changing the amplitude of the white level W while fixing the black level P of the inverted / non-inverted video signal, and adjusting the brightness means changing the amplitude of the inverted / non-inverted video signal. This is performed by changing the position of the black level P of the video signal.

Returning to FIG. 1, the operation of the first channel as the comparison channel processing circuit will be described. The first sample hold circuit 5 receives the white / black level inserted video signal A and performs a sub-sampling process to obtain a video signal for the first channel. The sub-sampling-processed video signal is latched by the common sample-and-hold circuit 6. The latched video signal is divided into inversion / non-inversion and input to the inversion amplification circuit 7, the non-inversion amplification circuit 8, the inversion brightness adjustment circuit 11, and the non-inversion brightness adjustment circuit 12, respectively. The inverted / non-inverted video signal is input to the switch 13 and switched by the switch 13 to become an AC video signal. The AC-converted video signal is output from the output unit 21 to the first channel of the liquid crystal display panel via the buffer circuit 14 for driving the load.

On the other hand, the inverted / non-inverted video signal output from the buffer circuit 14 is output to an inverted white level detector 17, an inverted black level detector 18, a non-inverted white level detector 19, and a non-inverted black level detector 20. Respectively. These detectors detect the inverting / non-inverting black level and white level using the video signal supplied to the first channel and output them to the comparators 9, 10, 15, and 16.
The comparators 9, 10, 15, and 16 compare the black level and white level of the first channel with the black level and white level of the reference channel processing circuit. As an example, the comparator 10 compares the black level with the inverted black level C output from the inverted black level detector 34 of the reference channel processing circuit in FIG.
The comparison result is fed back to the inverting brightness adjustment circuit 11. Here, if the inverted black level of the first channel is higher than the inverted black level C of the second channel as a reference, the output control of the comparator 10 is performed so that the black level of the first channel becomes smaller. That is, negative feedback is applied so that the black levels of the inverted video signals of the first channel and the second channel match. Hereinafter, the comparators 9, 15, and 16 similarly control the inverted / non-inverted white level and the non-inverted black level by comparing with the reference second channel.

Next, the operation of the third channel which is a comparison channel processing circuit will be described. In FIG. 3, the third
The sample hold circuit 38 receives the white / black level inserted video signal A and performs a sub-sampling process for obtaining a video signal for the third channel. The sub-sampled video signal is supplied to a common sample and hold circuit 6.
Performs a latch process. The latched video signal is divided into inverting / non-inverting signals, and the inverting amplifier circuit 39, the non-inverting amplifier circuit 40, and the inverting bright adjusting circuit 4
3 and is input to the non-inverted bright adjustment circuit 44.
The inverted / non-inverted video signal is input to the switch 45 and is switched by the switch 45 to become an AC video signal. The AC-converted video signal passes through a buffer circuit 46 and is output to an output unit 5.
3 to the third channel of the liquid crystal display panel.

On the other hand, the inverted / non-inverted video signal output from the buffer circuit 46 is output from an inverted white level detector 49, an inverted black level detector 50, a non-inverted white level detector 51, and a non-inverted black level detector 52. Respectively. These detectors detect the white level and the black level of the inverted / non-inverted video signal using the video signal supplied to the third channel. The white level and the black level are compared with the comparators 41 and 4.
2, 47 and 48 are compared with the reference white level and black level of the second channel. For example, the inverted black level of the third channel is compared with the inverted black level C output from the inverted black level detector 34 of FIG. 2 by the comparator 42, and if the inverted black level of the third channel is the inverted black level C of the second channel. If so, negative feedback is applied so that the black level of the third channel is reduced. Thereafter, the video signal control of the third channel is performed in the same manner, and the coincidence with the second channel is achieved. With such a negative feedback circuit, the video signal waveforms of the first and third channels are constantly controlled so as to match the second channel set for the target video signal waveform, and the first, second, and third channels are controlled. 3
The waveforms of the video signals of the channels become uniform.

Second Embodiment This embodiment is an example in which an intermediate level is detected and only brightness is automatically controlled instead of detecting the white level and the black level in the first embodiment. 4 to FIG.
This will be described with reference to FIG. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be partially omitted.

First, the configuration of the second embodiment will be described with reference to FIGS. FIG. 5 is a diagram showing a second embodiment of the liquid crystal driving device of the present invention. FIG. 6 is a block diagram showing a first channel, FIG. 6 is a block diagram showing a second channel, and FIG. FIG. 2 is a block diagram showing the configuration.

Reference numeral 100 in FIG. 5 indicates the liquid crystal driving device of the present invention. The first channel in the liquid crystal driving device 100 of the present invention is an example in which a predetermined color signal is divided into three and input to a signal line. For example, the input unit 2 to which a red video signal is input, and a white level in the input video signal And an intermediate level insertion circuit 101 for adding an intermediate level of the black level, a first sample and hold circuit 5 to which the intermediate level insertion video signal A 'is input, a common sample and hold circuit 6, an inverting amplifier circuit 7, a non-inverting amplifier circuit 8, Comparators 10 and 15, Inverted Bright Adjustment Circuit 11, Non-Inverted Bright Adjustment Circuit 12, Switch 1
3, a buffer circuit 14, an output unit 21 for outputting a video signal to the liquid crystal display panel, and the like. Further, an inverted intermediate level detector 102 connected to the buffer circuit 14 for detecting the intermediate level of the inverted video signal, and a non-inverted intermediate level detector 1 for detecting the intermediate level of the non-inverted video signal
03. Then, the inverted intermediate level detector 10
2 is connected to one end of a comparator 10, the output of which is connected to a control terminal 11a of an inverting bright adjustment circuit 11, the output of the non-inverting intermediate level detector 102 is connected to one end of a comparator 15, and its output is Control terminal 12a of adjustment circuit 12
To form luminance feedback means.

In FIG. 6, a second channel serving as a reference channel processing circuit includes an inverted video signal in addition to the first sample / hold circuit 22 and the common sample / hold circuit 6 to which the above-mentioned intermediate level inserted video signal A 'is input. Inverted brightness adjusting means 23 for adjusting brightness as a reference of the above, an inverted brightness adjusting circuit 29 to which the inverted brightness adjusting means 23 is connected, an inverted gain adjusting means 24 for adjusting a gain which is a reference of an inverted video signal, The output is connected to the control terminal 27a of the inverting amplifier 27 and is connected to the inverting amplifier 7 in FIG. 5 and the inverting amplifier 39 in FIG. Similarly, a non-inverting gain adjusting means 25 for adjusting a gain serving as a reference of a non-inverting video signal, and an output of which is supplied to a control terminal 28 a
And is connected as a non-inverting gain F to the non-inverting amplifier circuit 8 in FIG. 5 and the non-inverting amplifier circuit 40 in FIG. Further, a non-inverted brightness adjusting means 26 for adjusting brightness as a reference of a non-inverted video signal, and a non-inverted brightness adjusting circuit 3 to which the non-inverted brightness adjusting means 26 is connected.
0, a switch 31, a buffer circuit 32, an output section 37 for outputting a video signal to a liquid crystal display panel, an inverted intermediate level detector 104 for outputting an inverted intermediate level H, and a non-inverted intermediate level detection for outputting a non-inverted intermediate level J It comprises a vessel 105.

The third channel serving as a comparison channel processing circuit in FIG. 7 includes a third sample / hold circuit 38 to which the intermediate level inserted video signal A 'is input, a common sample / hold circuit 6, an inverting amplifier 39, and a non-inverting amplifier. 40, comparators 42 and 47, inverted brightness adjustment circuit 43,
Non-inverted brightness adjustment circuit 44, switch 45, buffer circuit 46, output unit 53 for outputting a video signal to a liquid crystal display panel, inverted intermediate level detector 106 for detecting an inverted intermediate level, and non-inverted for detecting a non-inverted intermediate level It comprises an intermediate level detector 107 and the like. The output of the inverted intermediate level detector 106 is connected to one end of the comparator 42, the output of which is connected to the control terminal 43a of the inverted brightness adjustment circuit 43, and the output of the non-inverted intermediate level detector 107 is connected to one end of the comparator 47. , The output of which is the non-inverting bright adjustment circuit 4.
4 is connected to the control terminal 44a to form luminance feedback means.

The operation of the driving circuit of the liquid crystal driving device having such a configuration will be described. For example, a red video signal input to the input unit 2 in FIG. 5 is input to the intermediate level insertion circuit 101. The intermediate level insertion circuit 101 generates an intermediate level X as a pre-process of the liquid crystal driving device of the present invention and inserts it into a video signal. Then, an intermediate level inserted video signal A ′ into which the intermediate level X has been inserted is supplied to each channel.

Turning to FIG. 6, the operation of the second channel serving as the reference channel processing circuit will be described. The intermediate level inserted video signal A 'is input to the second sample and hold circuit 22. The second sample and hold circuit 22 performs a sub-sampling process for dividing the video signal into three video signals. The sub-sampled video signal is latched by the common sample and hold circuit 6. These processes are performed by receiving a pulse from a timing generator (not shown). The latched video signal is divided into inverted / non-inverted signals and input to an inverting amplifier circuit 27 and a non-inverting amplifier circuit 28, respectively. The inverting amplifier circuit 27 is connected to an inverting gain adjusting means 24 via a control terminal 27a. By adjusting the inverting gain adjusting means 24, the gain of the inverting video signal serving as a reference is adjusted.
At the same time, the inverting amplifier 7 shown in FIG.
Are input to the inverting amplifier circuit 39. In this way, the gain of the inverted video signal is uniformly adjusted for each channel. Similarly, a non-inverting gain adjusting means 25 is connected to the non-inverting amplifying circuit 28 via a control terminal 28a, and by adjusting the non-inverting gain adjusting means 25, the gain of the reference non-inverting video signal is adjusted. At the same time, it is input to the non-inverting amplifier 8 in FIG. 5 and the non-inverting amplifier 40 in FIG. 7 as the non-inverting gain F. In this way, the gain of the non-inverted video signal is uniformly adjusted for each channel.

The inverted brightness adjusting circuit 29 and the non-inverted brightness adjusting circuit 30 are connected to the inverted brightness adjusting means 23 and the non-inverted brightness adjusting means 2 via control terminals 29a and 30a.
6 is connected, and by adjusting these adjusting means, the brightness of the reference inverted / non-inverted video signal is adjusted. The inverted / non-inverted video signal is input to the switch 31 and is switched by the switch 31 to be converted into an alternating current. The converted video signal is supplied to a buffer circuit 3
The signal is output from the output unit 37 to the liquid crystal display panel through the step 2.
On the other hand, the inverted / non-inverted video signal output from the buffer circuit 32 is input to the inverted intermediate level detector 104 and the non-inverted intermediate level detector 105, respectively. These detectors detect the respective intermediate levels and output them to the first and third channels as an inverted intermediate level H and a non-inverted intermediate level J.

Returning to FIG. 5, the operation of the first channel as the comparison channel processing circuit will be described. The first sample and hold circuit 5 receives the intermediate level inserted video signal A 'and performs a sub-sampling process to obtain a video signal for the first channel. The sub-sampling-processed video signal is latched by the common sample-and-hold circuit 6. The latched video signal is divided into inverted / non-inverted signals and input to the inverting amplifier circuit 7 and the non-inverting amplifier circuit 8, respectively. In the inverting amplifier circuit 7, the same level as that of the second channel is controlled by the inverting gain G described above.
In the non-inverting amplifier circuit 8, the same level as that of the second channel is controlled by the above-mentioned non-inverting gain F. The gain-adjusted video signal is supplied to the next-stage inverted brightness adjustment circuit 11,
It is output to the non-inverted bright adjustment circuit 12.

The inverted / non-inverted video signal is input to the switch 13 and switched by the switch 13 to be converted into an alternating current. The AC-converted video signal is output from the output unit 21 to the liquid crystal display panel via the buffer circuit 14. On the other hand, the video signal output from the buffer circuit 14 is input to the inverted intermediate level detector 102 and the non-inverted intermediate level detector 103, respectively. The inverted intermediate level detector 102 detects the intermediate level of the inverted video signal and compares the output with the comparator 1
Output to 0. The non-inverted intermediate level detector 103 detects the intermediate level of the non-inverted video signal and outputs its output to the comparator 15. The inverted intermediate level of the first channel and the inverted intermediate level H of the second channel are compared by the comparator 10. As a result, if the inverted intermediate level of the first channel is larger than the inverted intermediate level H of the second channel, The output of the comparator 10 is controlled so that the intermediate level of one channel is reduced. That is, negative feedback is applied to the inverted brightness adjustment circuit 11 so that the inverted intermediate levels of the first channel and the second channel match. Similarly, the non-inverting side bright adjustment circuit 12 is controlled by the non-inverting intermediate level J.

Next, the operation of the third channel serving as the comparison channel processing circuit will be described. In FIG. 7, the third sample-and-hold circuit 38 receives the intermediate-level inserted video signal A 'and performs a sub-sampling process to obtain a video signal for the third channel. The sub-sampling-processed video signal is latched by the common sample-and-hold circuit 6. The latched video signal is divided into inversion / non-inversion and input to the inversion amplification circuit 39, the non-inversion amplification circuit 40, the inversion brightness adjustment circuit 43, and the non-inversion brightness adjustment circuit 44, respectively. The inverted / non-inverted video signal is input to the switch 45,
It is switched and exchanged at. The AC-converted video signal is output from the output unit 53 to the liquid crystal display panel via the buffer circuit 46.

On the other hand, the inverted / non-inverted video signal output from the buffer circuit 46 is output to the inverted intermediate level detector 106,
The signal is input to the non-inverting intermediate level detector 107. These detectors detect the intermediate level using the inverted / non-inverted video signal. For example, the comparator 42 compares the inverted intermediate level output from the third channel with the inverted intermediate level H output from the second channel as a reference, and the inverted intermediate level of the third channel is higher than the inverted intermediate level H of the second channel. If it is larger, negative feedback is applied so that the intermediate level of the third channel becomes smaller. in this way,
According to the present embodiment, since only the intermediate level of the inverted / non-inverted video signal is detected and controlled, it is possible to perform control so that the video signal waveforms of the first, second, and third channels are aligned with a small circuit scale. it can.

The present invention is not limited to the above embodiment,
Various embodiments can be adopted. For example, in the present embodiment, the case of the three-channel control for the three-dot simultaneous sampling method has been described as an example. However, the present invention can be applied to the six-channel control and the twelve-channel control for the six-dot simultaneous sampling, as well as the control of multiple channels. However, the present invention is not limited to the number of control channels. Needless to say, the present invention can be appropriately applied without departing from the gist of the present invention.

[0041]

As described above, according to the liquid crystal driving apparatus of the present invention, in a method of simultaneously sampling a plurality of channels of video signals and driving the liquid crystal display panel, the video level of the reference channel processing circuit is detected. Since the video level of the comparison channel processing circuit is automatically controlled, display unevenness caused by variations in the video signal written to each channel can be improved, and the display quality can be improved. In addition, since the adjustment of the gain, brightness, and the like of the comparison channel processing circuit is automatically performed, the time required for the adjustment and inspection can be significantly reduced, and the production efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a first embodiment of a liquid crystal driving device according to the present invention, and is a block diagram illustrating a first channel.

FIG. 2 is a diagram illustrating a first embodiment of a liquid crystal driving device according to the present invention, and is a block diagram illustrating a second channel.

FIG. 3 is a diagram showing a first embodiment of the liquid crystal driving device of the present invention, and is a block diagram showing a third channel.

FIG. 4 is a waveform diagram showing inverted / non-inverted video signals of the liquid crystal driving device of the present invention.

FIG. 5 is a diagram showing a second embodiment of the liquid crystal driving device of the present invention, and is a block diagram showing a first channel.

FIG. 6 is a diagram showing a second embodiment of the liquid crystal driving device of the present invention, and is a block diagram showing a second channel.

FIG. 7 is a diagram showing a second embodiment of the liquid crystal driving device of the present invention, and is a block diagram showing a third channel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 100 Liquid crystal drive device of this invention 2 Input part 3 White level insertion circuit 4 Black level insertion circuit 5 First sample hold circuit 6 Common sample hold circuit 7, 27, 39 Inverting amplifier circuit 8, 28, 40 Non-inverting amplifier circuit 9, 10, 15, 16, 41, 42, 47, 48 Comparator 11, 29, 43 Inverted brightness adjustment circuit 12, 30, 44 Non-inverted brightness adjustment circuit 13, 31, 45 Switch 14, 32, 46 Buffer circuit 17 , 33, 49 Inverted white level detector 18, 34, 50 Inverted black level detector 19, 35, 51 Non-inverted white level detector 20, 36, 52 Non-inverted black level detector 21, 37, 53 Output section 22 2 sample and hold circuit 23 inverting brightness adjusting means 24 inverting gain adjusting means 25 non-inverting gain adjusting means 26 non-inverting bright adjusting means 38 third sample and hold circuit 101 intermediate level inserting circuits 102, 104, 106 inverting intermediate level detectors 103, 105 , 107 non Rolling the intermediate level detector W white level P black level X intermediate level K common voltage

Claims (2)

(57) [Claims] 1. A liquid crystal driving device for simultaneously sampling and driving a plurality of channels when writing video signals to a liquid crystal display panel, comprising: a reference channel processing circuit; and at least one comparison channel processing circuit. A white level insertion circuit for inserting a white level into the extracted video signal, a black level insertion circuit for inserting a black level, and the reference channel processing circuit, wherein the video signal having the white level and the black level inserted is sampled. A sample-and-hold circuit for inverting and inverting / amplifying the video signal by inverting / non-inverting the video signal.
A non-inverting amplifier circuit; an inverting / non-inverting gain adjusting means connected to the inverting / non-inverting amplifier circuit; an inverting / non-inverting luminance adjusting circuit for adjusting the luminance of the inverting / non-inverting video signal; Inverting / non-inverting luminance adjusting means connected to a / non-inverting luminance adjusting circuit; a switch circuit for switching the inverting / non-inverting video signal; a buffer circuit; and an output unit; Inverted / non-inverted white level detector that outputs the white level of the image signal as a reference white level to the comparison channel processing circuit, and outputs the black level of the inverted / non-inverted video signal to the comparison channel processing circuit as a reference black level. An inversion / non-inversion black level detector; and the comparison channel processing circuit further includes: the sample-and-hold circuit; Inversion /
A non-inverting amplifier circuit, an inverting / non-inverting luminance adjusting circuit for adjusting the luminance of the inverted / non-inverting video signal, a switch circuit for switching the inverting / non-inverting video signal, a buffer circuit, and an output unit Gain feedback means for detecting a white level of the inverted / non-inverted video signal and comparing the white level with the reference white level to control the inverted / non-inverted amplifier circuit; Brightness feedback means for detecting the level and comparing the level with the reference black level to control the inversion / non-inversion brightness adjustment circuit, wherein the gain feedback means and the brightness feedback means enable the gain of the comparison channel processing circuit to be controlled. A liquid crystal driving device for automatically controlling the brightness and brightness so as to match the reference channel processing circuit. 2. A liquid crystal drive device for simultaneously sampling and driving a plurality of channels when writing a video signal to a liquid crystal display panel, comprising: a reference channel processing circuit; and at least one comparison channel processing circuit. An intermediate level insertion circuit that inserts an intermediate level between a white level and a black level into the output video signal; a sample and hold circuit that samples the video signal into which the intermediate level has been inserted; Is divided into inverted / non-inverted and amplified.
A non-inverting amplifier circuit; an inverting / non-inverting gain adjusting means connected to the inverting / non-inverting amplifier circuit and the comparison channel processing circuit; and an inverting / non-inverting circuit for adjusting the luminance of the inverting / non-inverting video signal. A luminance adjustment circuit, an inversion / non-inversion luminance adjustment means connected to the inversion / non-inversion luminance adjustment circuit, a switch circuit for switching the inversion / non-inversion video signal, a buffer circuit, and an output unit; An inverted / non-inverted intermediate level detector that outputs an intermediate level of the inverted / non-inverted video signal as a reference intermediate level to the comparison channel processing circuit; The video signal is divided and inverted and amplified, and the inverted / non-inverted gain adjusting means is connected to the inverted / non-inverted gain adjusting means.
A non-inverting amplifier circuit, an inverting / non-inverting luminance adjusting circuit for adjusting the luminance of the inverted / non-inverting video signal, a switch circuit for switching the inverting / non-inverting video signal, a buffer circuit, and an output unit Brightness feedback means for detecting an intermediate level of the inverted / non-inverted video signal and comparing the inverted / non-inverted video signal with the reference intermediate level to control the inverted / non-inverted amplifier circuit; A liquid crystal driving device which automatically controls the luminance of a channel processing circuit so as to match the reference channel processing circuit.