JP2677567B2 - Liquid crystal display - Google Patents

Description

TECHNICAL FIELD The present invention relates to a liquid crystal display device for a liquid crystal television. [Prior Art] LCD color TVs are designed to produce various colors by overlapping the RGB color filters on the output electrodes of the segment driver in order and controlling their brightness, but high image quality is required. When this happens, it becomes necessary to make the RGB filter finer and increase the number of outputs of the segment driver accordingly. with this,
The sampling frequency of the A / D converter will also increase, and the noise generated from the digital circuit will increase, which will adversely affect the reception performance of the TV. As a method of using a fine RGB filter without increasing the A / D conversion frequency, branch the output electrodes of the segment driver and increase the number of RGB filters without changing the A / D conversion frequency of the segment driver. And the so-called half-pitch shift shape in which adjacent pixels in the horizontal direction are vertically displaced from each other by half, and the common electrode shape is jagged. In one horizontal scanning line), there is a half pitch shift method in which only the points at the positions corresponding to the odd (or even) number of the segment driver output are sampled, and the remaining half is sampled at the next 1H. FIG. 4 is a plan view showing an example of the pixel shape of a conventional liquid crystal color television, and FIG. 4 (a) shows the pixel shape of the electrode branch method. The circles shown in the pixels indicate the positions to which the data sampled during the period of the video signal 1H correspond, and one data corresponds to every other segment electrode. FIG. 4 (b) shows the pixel shape of the half pitch shift system, similarly, the circles indicate the positions corresponding to the sampling data, and one data corresponds to every other segment electrode. The black circles represent the sampling data positions at the 1H and the white circles at the 2H, and in this method, the selection signal is applied to the common electrode when the data for the above 2H is complete. [Problems to be Solved by the Invention] However, each of the above two types has a problem. First, in the electrode branching method, the two segment electrodes that are apart from each other fall over with the same sampling data, so the resolution is significantly reduced. Even if the color mixture looks good at first glance, the combination of the RGB filters is irregular and the color shift is likely to occur. In particular, there is a problem that the edge part becomes reddish or bluish in a white vertical line. In the half-pitch shift method, in addition to the drawback that the horizontal lines are jagged, when the horizontal lines are thin, the colors are expressed by a combination of RGB that are separated from each other, and the color mixing property is partially reduced. Furthermore, since the shape of the common electrode is not straightforward, it is difficult to make and the alignment with the segment electrode is difficult. [Means for Solving Problems] A control circuit for A / D converting a video signal and generating a timing signal for driving a liquid crystal panel, a common driver for driving a common electrode based on the timing signal, and the A / D conversion In a liquid crystal display device comprising a segment driver that drives signal electrodes of a liquid crystal panel based on data and a matrix liquid crystal panel, the segment driver has a line memory for temporarily storing at least the A / D conversion data and the line memory for temporarily storing the A / D conversion data. The line memory includes an odd-numbered input circuit for sequentially storing data at odd-numbered memory and an even-numbered input circuit for sequentially storing data at even-numbered memory. The line switching sampling circuit that repeats the odd sampling and the even sampling alternately for each (one horizontal scanning line) By providing a frame inversion circuit that switches the order of odd and even numbers for each frame, the number of pixels is doubled without increasing the A / D conversion frequency, and sampling is performed at all points corresponding to the pixels. [Embodiment] FIG. 1 is a circuit block diagram showing an example of a liquid crystal display device of the present invention. Reference numeral 1 is a control circuit, which includes a reference oscillator that generates a reference clock for creating a digital signal and a sync separation circuit that extracts a sync signal from a video signal, and a line signal HS and frame that is inverted every horizontal scanning (1H). A control circuit 11 that creates a frame signal FR that is inverted every time and other various control signals, and an A / D converter 12 that A / D converts a video signal to create a 4-bit digital signal.
R, 12G, 12B and a multiplexer 13 that outputs any one of the output signals of the three A / D converters under the control of the control circuit 11, and a signal from the control circuit 11 A pulse generator 14 that creates two-phase sampling timing pulses PA and PB, and a line switching circuit 15 that alternately connects and disconnects the timing pulses PA and PB according to a line signal HS from the control circuit 11.
And a frame inversion circuit 16 which inverts the connection / disconnection order of the line switching circuit 15 in accordance with a frame signal FR from the control circuit 11. Reference numeral 2 is a segment driver, which is an odd-cell sampling shift register A2 as an odd-numbered input circuit.
1, an even-cell sampling shift register B22 as an even-numbered input circuit, and 4 from the control circuit 1
A data register 23 that stores bit data at the timing of the output signals of the shift registers 21 and 22,
It comprises a pulse width modulator 24 which simultaneously latches all the stored contents of the data register 23 and outputs a pulse width modulated signal according to the latch contents as a segment signal. Reference numeral 3 denotes a common driver, which outputs a selection signal for scanning every 1H to 240 common electrodes under the control of the signal from the control circuit 1. In some cases, so-called convolutional scanning is performed in which scanning is performed while simultaneously outputting selection signals to a plurality of electrodes. Reference numeral 4 denotes a dot matrix liquid crystal panel. FIG. 2 is a plan view showing the electrode shape of the liquid crystal panel used in the liquid crystal display device of the present invention. The circles shown in the pixels indicate the positions to which the sampling data correspond, the white circles indicate the sampling data of the first and second fields, and the black circles indicate the sampling data of the next frame, that is, the third and fourth fields. ing. Data correspond to only every other pixel in one frame, but data corresponding to the remaining pixels are sampled in the next frame. The common electrode is a normal operation in which scanning is selected every 1H. Therefore, the pixels not sampled in the 1H period use the data 1H before. Therefore, averaging is performed in the vertical direction, and smoothness appears as an image. FIG. 3 is a pattern diagram showing combinations of data to be averaged. FIG. 3 (a) shows the first field, FIG. 3 (b) shows the second field, and FIG. 3 (c) shows The first field of the next frame (hereinafter referred to as the third field) and FIG. 3D show the second field (hereinafter referred to as the fourth field). The squares represent a part of the dot configuration of the panel, and in the squares, the number of the video signal scanning line data for which each of the first to fourth fields is turned on is shown. The number of video signal scanning lines is one frame effective scanning line
480 lines are counted from the top, and the first field is 1, 3, 5, ..., The second field is 2, 4,
6, ... The circles around the numbers mean new data just sampled. Looking at the figure, the dots in the upper left are 1 and 2 in the first field.
The field is 4, the third field is 3, and the fourth field is 2. As a result, averaging of 1 to 4 is performed, and the dot on the right side is also an average of 1 to 4. After all, the top horizontal row displays the average of 1-4, the next row the average of 3-6, the next average of 5-8, etc. become. The configuration of the present invention is not limited to the above, and even more advantageous is obtained by using a convolution scanning type common driver. EFFECTS OF THE INVENTION According to the present invention, the number of pixels can be doubled at once without increasing the sampling frequency, and since there is no color misregistration or data loss, extremely high color mixture and high resolution are achieved. Good images can be obtained, and the commercial value of LCD TVs can be dramatically increased.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit block diagram showing an embodiment of a liquid crystal display device of the present invention, and FIG. 2 is a plan view showing electrode shapes of a liquid crystal panel used in the liquid crystal display device of the present invention. FIG. 3 is a pattern diagram showing a combination of data to be averaged, and FIG. 4 is a plan view showing an example of a pixel shape of a conventional liquid crystal color television. 1 ... Control circuit, 2 ... Segment driver, 11 ... Control circuit, 12R, 12G, 12B ... A / D converter, 15 ... Line switching circuit, 16 ... Frame inversion circuit.

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Claims (1)

(57) [Claims] A control circuit for A / D converting the video signal and creating a timing signal for driving the liquid crystal panel, a common driver for driving a common electrode based on the timing signal, and a signal electrode of the liquid crystal panel based on the A / D conversion data. In a liquid crystal display device composed of a driving segment driver and a matrix liquid crystal panel, the segment driver has at least a line memory for temporarily storing the A / D conversion data and an odd number of data in the line memory sequentially. An odd-numbered input circuit for storing data and an even-numbered input circuit for storing even-numbered data one after another are provided, and the control circuit performs odd sampling every 1H (one horizontal scanning line). And a line switching sampling circuit that alternately repeats even sampling The liquid crystal display device characterized by comprising a frame inversion circuit is changing.