JPH0740178B2 - Liquid crystal display - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive circuit for a liquid crystal display device that performs color display.

[0002]

2. Description of the Related Art A driving circuit of a conventional liquid crystal display device using an active matrix substrate is shown in FIGS.

FIG. 1 is a circuit diagram of an active matrix panel and a peripheral drive circuit. In FIG. 1, 101 is a source line (column line) side drive circuit, 102 is an active matrix panel, 103 is a gate line (row line) side drive circuit, 104 is a shift register, 105 is a clock input terminal, and 106 is a sample data input terminal. , 107 is a video input terminal, 108 is a MOS transistor, 109 is a pixel, 110 is a shift register, 111 is a scan data input terminal, 112
Is a clock input terminal, 113 is a MOS transistor, 114
Is a capacitor, 115 is a liquid crystal, and 116 is a common electrode.

FIG. 2 is a block diagram of a video signal processing circuit. In FIG. 2, 201 is a video input terminal, 202 is a preamplifier, 203 is a complementary polarity video signal generator, 204 is a frame change switch, 205 is a frame input terminal, 206 is a buffer amplifier, and 207 is a video output terminal.

[0005]

In the conventional liquid crystal display device, monochrome display is performed. As a color display, a method of providing a color filter on each pixel is currently proposed. However, in the drive circuit of the conventional liquid crystal display device, an independent primary color signal cannot be applied to each pixel. There is only one signal processing system for video signals. Therefore, it is unsuitable as a driving circuit for color display. There were drawbacks as described above.

The present invention eliminates such drawbacks, and a first object thereof is to provide an optimum drive circuit for a liquid crystal display device which performs color display using an active matrix substrate. An object is to provide a drive circuit that can be easily integrated into a circuit.

[0007]

According to the present invention, liquid crystal is enclosed in a pair of substrates, and pixel electrodes are arranged in a matrix on the substrates, and are arranged in a mosaic pattern corresponding to each of the pixel electrodes. In the liquid crystal display device having the three primary color filters, the arrangement of the three colors of the three primary color filters is shifted in the column direction and the row direction on a column-by-column basis and a row-by-row basis. First, second and third signal selecting means for switching and selecting the primary color signals, first sampling means for sampling the primary color signals from the first signal selecting means by the clock signal and supplying the sampled primary color signals to the first column line, Second sampling means for sampling the primary color signal from the second signal selecting means by a clock signal and supplying it to the second column line, and primary color signal from the third signal selecting means. Are sampled by a clock signal and supplied to the third column line, and the primary color signal selection timings of the first, second and third signal selection means are determined by the pixels arranged in the matrix. In synchronization with the switching of each row line of the electrodes, the first and second
And the operation of sampling the primary color signals by the third sampling means is performed at time series timings corresponding to the screen-like arrangement coordinates of the three primary color filters.
Further, it is characterized in that an AC conversion means for making the primary color signal an alternating signal of positive polarity and negative polarity is provided in front of the third signal selecting means.

[0008]

Since the timing of selecting the primary color signals is synchronized with the row switching of the pixel electrodes arranged in a matrix, no matter which pattern the color filters are arranged in, the pixel electrodes in the positions corresponding to the mosaic arrangement are The corresponding primary color signals can be accurately supplied. Further, since the timing of the primary color signals is synchronized with the row switching of the pixels, it is not necessary to select a color with a high frequency within one horizontal scanning period, and a row switching synchronizing signal or a horizontal scanning synchronizing signal of a television signal should be used. You can

Further, since the primary color signal sampling means, the second primary color signal sampling means, and the third primary color signal sampling means do not simultaneously sample the primary color signals, the three primary color signals are not sampled at the same time and are adjacent to each other. Between pixels, the displayed image has a high definition and a false signal (image, color or moire fringe) is unlikely to occur. In particular, the present invention is characterized in that the AC converting means is provided in front of the signal selecting means. Since the switch of the alternating current means and the switch of the signal selection means are arranged adjacent to each other, the integrated switch group can be integrated into an analog circuit (for example, CMOS).

[0010]

Embodiments of the present invention will now be described with reference to the accompanying drawings.

FIG. 3 is a circuit diagram of an active matrix panel and a peripheral drive circuit of the liquid crystal display device of the present invention. In FIG. 3, 301 is a source line (column line) side drive circuit, 302 is an active matrix panel, 303 is a gate line (row line) side drive circuit, 304 is a shift register, 305 is a clock input terminal, and 306 is a sample data input terminal. , 307 is a primary color signal input terminal, 308 is a MOS transistor, 309 is a pixel, 310 is a shift register, 311 is a scan data input terminal, 312 is a clock input terminal, 313
Is a MOS transistor, 314 is a capacitor, 315 is a liquid crystal, and 316 is a common electrode.

As is apparent from FIG. 3, in the present invention, a plurality of (three) primary color signal input terminals 307, 307, 307 are provided, and each primary color signal (R primary color signal, G primary color signal, B primary color signal) is added separately. . This is to improve the degree of separation of the primary color signals, and if an attempt is made to add them using a common input line, the sampling frequency becomes high and crosstalk will occur between the primary color signals.

The present invention has been described based on an example in which each pixel is provided with a mosaic color filter. An example of the arrangement of the color filters is shown in FIG.
(A) is a pattern in which the arrangement in RGB order is shifted by one pixel for each row line.

In FIG. 4, R is a red color filter, G is a green color filter, and B is a blue color filter for performing color display using an additive method.

FIG. 5 is a block diagram of a color signal processing circuit in the case where the color filter array shown in FIG. 4A is used.

The color difference signal R-Y is sent to the terminal 501 through the color difference signal G
-Y is input to the terminal 502, the color difference signal BY is input to the terminal 503, and the luminance signal Y is input to the terminal 504. These color difference signals are converted into R, G, B in the primary color signal regenerators 511, 512, 513.
Reproduced to primary color signal. Reference numeral 514 is a luminance signal buffer. The reproduced primary color signals R, G and B are switched and selected by R-G-B signal selection switches 701, 702 and 703, respectively. The R-G-B signal selection switches 701, 702, 703 are
The switching timing is determined by the row line switching signal (horizontal synchronizing signal) input to the terminal 704. R-G-B
The R, G, B primary color signals which are mutually exclusive selected by the signal selection switches 701, 702, 703 are complementary polarity primary color signal generators 521,
Input to 522,523. This complementary polarity primary color signal generator 52
1,522,523 generate R, G, B primary color signals of positive polarity and negative polarity. A unipolar signal of these complementary-polarity primary color signals is selected for each frame by frame selection switches 531, 532, and 533. Frame selection switch 531,532,533
Are controlled by the frame signal input to terminal 534. These selected unipolar signals are transferred to the buffers 541, 542,
It is amplified by 543 and taken out to output terminals 711, 712, 713.

Here, the output terminals 711 are the first, fourth, and seventh from the left in the active matrix of FIG.
... (1 + 3K) th, (where K = 0, 1, 2, ...) If it is connected to the primary color signal input terminal 307 connected to the column line, the first row line from the top is selected. R primary color signal, the B primary color signal is transmitted when the second row line from the top is selected, and the G primary color signal is transmitted when the third row line from the top is selected. -G-B signal selection switch 701 has terminal 704
Switching control is performed by the row line switching signal (horizontal synchronizing signal). Similarly, the output terminal 712 is the second, the fifth, the eighth from the left in the active matrix of FIG.
If it is connected to the primary color signal input terminal 307 connected to the (2 + 3K) th column (where K = 0, 1, 2, ...) When the first row line from the top is selected. R- is used to transmit the G primary color signal, the R primary color signal when the second row line from the top is selected, and the B primary color signal when the third row line from the top is selected. The G-B signal selection switch 702 is switched and controlled by a row line switching signal (horizontal synchronizing signal) at the terminal 704. Similarly, the output terminal 713 is the third, sixth, ninth from the left in the active matrix of FIG. 3 (3
(+ 3K) th (K = 0, 1, 2, ...) If connected to the primary color signal input terminal 307 connected to the column line, when the first row line from the top is selected For the B primary color signal, the G primary color signal is transmitted when the second row line from the top is selected, and the R primary color signal is transmitted when the third row line from the top is selected. The -B signal selection switch 703 is switched and controlled by the row line switching signal (horizontal synchronizing signal) at the terminal 704. When the second row line from the top is selected by the gate line side drive circuit 303, the R primary color signal is input to the first primary color signal input terminal 307 from the bottom and the G primary color signal is input to the second primary color signal input terminal 307 from the bottom. The primary color signal is input to the third primary color signal input terminal 307 from the bottom, and the B primary color signal is input during that time (horizontal scanning period), the MOS transistor 108 is turned on by the first clock, and the R primary color signal is sampled. This is supplied to the pixel in the first row and the first column, the MOS transistor 108 is turned on by the next clock, the G primary color signal is sampled and supplied to the pixel in the first row and the second column, and the MOS transistor 108 is supplied by the next clock.
Is turned on, the B primary color signal is sampled, and this is supplied to the pixel in the first row and third column. Similarly, from the top 2
When the second row line is selected by the gate line side drive circuit 303, the B primary color signal is input to the first primary color signal input terminal 307 from the bottom, and the R primary color signal is input to the second primary color signal input terminal 307 from the bottom. , The G primary color signal is input to the third primary color signal input terminal 307 from the bottom, and during that time (horizontal scanning period), the MOS transistor 108 is turned on by the first clock, and the B primary color signal is sampled. The signal is supplied to the pixel in the first column, the MOS transistor 108 is turned on by the next clock, the R primary color signal is sampled and supplied to the pixel in the second row and second column, and the MOS transistor 108 is turned on by the next clock. The G primary color signal is sampled and supplied to the pixel in the second row and third column. In the same way, from the top 3
When the second row line is selected by the gate line side drive circuit 303, the B primary color signal is input to the first primary color signal input terminal 307 from the bottom, and the B primary color signal is input to the second primary color signal input terminal 307 from the bottom. , The R primary color signal is input to the third primary color signal input terminal 307 from the bottom, and during that time (horizontal scanning period), the MOS transistor 108 is turned on by the first clock, and the G primary color signal is sampled. It is supplied to the pixel in the first column, the MOS transistor 108 is turned on by the next clock, the B primary color signal is sampled and supplied to the pixel in the third row and second column, and the MOS transistor 108 is turned on by the next clock. The R primary color signal is sampled and supplied to the pixel in the third row and third column.

FIG. 6 is a circuit block diagram in which the R-G-B signal selection switches 701, 702, 703 of FIG. 5 are arranged after the frame selection switches 531, 532, 533. Except for this point, there is no difference from the configuration of FIG. FIG. 7 is a block diagram showing a color signal processing circuit according to another embodiment of the present invention.
An example of using the color filter of FIG. 4B is shown.
501 is an R-Y signal input terminal, 502 is a G-Y signal input terminal, 503 is a BY signal input terminal, 504 is a Y signal input terminal, 511, 512, 513 F primary color signal regenerator, and 514 is a Y signal buffer. , 521, 522, 523 are complementary polarity primary color signal generators, 531, 532, 533 are frame changeover switches, 53
4 is a frame input terminal, 541, 542 and 543 are buffer amplifiers, 551 is a red primary color signal output terminal, 552 is a green primary color signal output terminal, and 553 is a blue primary color signal output terminal.
In FIG. 7, the color difference signals input to 501, 502, and 503 and 504
The luminance signal input to is reproduced to primary color signals at 511, 512 and 513, and is made into primary color signals of complementary polarities at 521, 522 and 523 for AC driving of the liquid crystal. The complementary-color primary color signals are extracted by the 531, 532, and 533 K switches controlled by the 534 frame signal, and only one of the polarities is extracted, buffer-amplified by 541, 542, and 543, and input to the source side drive circuit.

The present invention provides a drive circuit most suitable for a liquid crystal display device which performs color display using an active matrix substrate, and its features are as follows. Since the primary color signals (red, blue, green) are added to separate common lines (panel peripheral source side drive circuit), there is no color shift or crosstalk due to sample hold shift, and good color reproducibility. Although FIG. 4A shows an example of a color filter mosaic pattern, it can be applied to various other pixel arrangements such as a color filter. Of course, the pattern shown in FIG. It is possible to support without switching control of the switches 701, 702, 703. The color signal processing circuit, which has a simple circuit configuration and drives a capacitive load, has low power and is well adapted to the low power of liquid crystal. It is easy to interface with the demodulation circuit of the conventional color television.

[0020]

As described above, according to the present invention, the first, second and third signal selecting means for switching and selecting exclusive primary color signals among the three primary color signals at the same timing, and the first signal selection. A first AC converting means for making the primary color signal selected by the means an alternating signal of positive polarity and a negative polarity, and a primary alternating signal for making the primary color signal selected by the second signal selection means an alternating signal of a positive polarity and a negative polarity 2 AC conversion means, the primary color signal selection timing of the first, second and third signal selection means,
The primary color signal sampling operations of the first, second and third sampling means are synchronized with the switching of each row line of the pixel electrodes arranged in a matrix, and the operations of the primary color signal sampling are performed in time series corresponding to the screen-like arrangement coordinates of the three primary color filters. Since it is characterized by being performed at the timing, the following effects are obtained.

That is, since the timing of selecting primary color signals is synchronized with the row switching of pixel electrodes arranged in a matrix, no matter what pattern the color filters are arranged in a mosaic, the pixels at the positions corresponding to the mosaic arrangement are arranged. The corresponding primary color signals can be accurately supplied to the electrodes. In other words, since the degree of freedom in selecting the color filter mosaic array pattern for color display is increased, high-quality color display is possible by adopting a suitable mosaic array pattern in consideration of filter characteristics and the like.

Further, since the timing of the primary color signal is synchronized with the row switching of the pixels, it is not necessary to select a color at a high frequency within one horizontal scanning period, and a row switching synchronizing signal or a horizontal scanning synchronizing signal of a television signal is used. Can be used.

Further, since the primary color signal sampling means, the second primary color signal sampling means, and the third primary color signal sampling means do not simultaneously sample the primary color signals, the three primary color signals are not sampled at the same time and are adjacent to each other. Between pixels, the displayed image has a high definition and a false signal (image, color or moire fringe) is unlikely to occur.

In particular, the present invention is characterized in that the AC conversion means is provided before the signal selection means. Since the alternating current means is generally composed of a complementary polarity generator for generating positive and negative polarity signals and a switch for alternately selecting the respective polarities, the alternating current means is arranged in front of the signal selecting means. With this arrangement, the switch of the AC conversion means and the switch of the signal selection means can be arranged adjacent to each other, and as a result, the integrated switch group can be integrated into an analog switch (for example, CMOS). On the contrary, if the AC converting means is provided in the subsequent stage of the signal selecting means, the complementary polarity generator is interposed between the switch of the signal selecting means and the switch of the AC converting means.
It becomes an obstacle to integration into an integrated circuit. Therefore, according to the present invention, it is advantageous to integrate the drive circuit into an integrated circuit and contributes to downsizing of the liquid crystal display device.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a conventional active matrix panel and peripheral drive circuit.

FIG. 2 is a block diagram of a conventional video signal processing circuit.

FIG. 3 is a circuit diagram of an active matrix panel and a peripheral drive circuit according to an embodiment of the present invention.

FIG. 4A is an array pattern diagram of color filters used in the embodiment, and FIG. 4B is an array pattern diagram of other color filters.

FIG. 5 is a block diagram showing an example of a color signal processing circuit used in the same embodiment.

FIG. 6 is a block diagram showing another example of a color signal processing circuit used in the same embodiment.

FIG. 7 is a block diagram showing an example of a color signal processing circuit used in another embodiment of the present invention.

[Explanation of main symbols]

 108 ... MOS transistor 301 ... Source line side drive circuit 302 ... Active matrix panel 303 ... Gate line side drive circuit 304, 310 ... Shift register 305 ... Clock input terminal 306 ... Sample data input terminal 307 ... Primary color signal input terminal 309 ... Pixel 315 ... Liquid crystal 511,512,513… Primary color signal generator 521,522,523… Complementary polarity primary color signal generator 531,532,533… Frame selection switch 701,702,703… R-G-B primary color signal selection switch 701,702,703… Output terminal

Claims (1)

[Claims] 1. A liquid crystal having a pair of substrates filled with liquid crystal, pixel electrodes arranged on the substrates in a matrix, and three primary color filters arranged in a mosaic corresponding to each of the pixel electrodes. In the display device, the arrays of the respective colors of the three primary color filters are shifted in the column direction and the row direction on a column-by-column basis and a row-by-row basis, and exclusive primary color signals among the three primary color signals are switched and selected at the same timing. First, second and third signal selecting means,
First sampling means for sampling the primary color signal from the first signal selecting means with a clock signal and supplying it to the first column line, and sampling the primary color signal from the second signal selecting means with a clock signal for a second It has a second sampling means for supplying to the column line and a third sampling means for sampling the primary color signal from the third signal selecting means with a clock signal and supplying it to the third column line. And the primary color signal selection timing of the third signal selection means is synchronized with the switching of each row line of the pixel electrodes arranged in the matrix, and the first, second and third
The primary color signal sampling operation of the sampling means is performed at time series timings corresponding to the screen-like arrangement coordinates of the three primary color filters, and the first, second, and third
A liquid crystal display device, characterized in that each of the liquid crystal display devices is provided in front of the signal selecting means with alternating current means for converting primary color signals into positive and negative alternating signals.