JPS61262725A - Picture density displaying method using liquid - Google Patents

Abstract

PURPOSE:To display a picture of high quality prevented from flickering by dividing each dot constituting a dot matrix into two or more sections having different area ratio and processing each divided element by the digital signal of a required picture signal to display each dot as density in accordance with the change of the picture signals. CONSTITUTION:When a picture signal is inputted to a comparator 9, the density level of the picture signal is compared by the 1st-3rd comparators 9a-9c and an 'H' or 'L' digital signal is outputted to form segment data A, B. When the elements 11a, 11b of each dot 11 connected to the COM1 of a common electrode 2 are turned on, the segment data A, B are outputted from a segment driver 14 to drive the elements 11a, 11b and display the density. Since the area ratio of the large hook-like element 11a to the small square element 11b is set up to about 2:1, at least four kinds of density display can be obtained in accordance with the driving state of the elements 11a, 11b.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for displaying shading of images using liquid crystal patterns.

[Prior art]

Conventionally, the relationship between the driving time ratio of each dot constituting a liquid crystal display and the gray level is as shown in the relationship diagram of FIG. % drive will turn gray, and 100% drive will turn black.Using this phenomenon, we created a liquid crystal pattern that displays an image in three gradations on each dot of the dot matrix of the liquid crystal display. A method for displaying image shading is known. The block diagram of FIG. 6 uses this conventional display method.

1 is each dot constituting the liquid crystal dot matrix X, and 2 is a common electrode connected to each dot L.

3 is a common driver that sequentially drives the common electrodes 2 in synchronization with the scanning signal; 4 is a segment electrode connected to each dot l; 5 is a segment driver that drives the segment electrode 4; A shift clock generator that provides a synchronized shift clock to the segment driver 5, 7 a frequency divider circuit that divides the frequency of the scanning signal by 1/n, and 8 a selection order that generates a selection order signal using the signal from the frequency divider circuit 7. 9 is a comparator; 9a is a first comparator that compares image signals at black level; 9b is a second comparator that compares image signals at dark gray level; 9C is a third comparator that compares image signals at light gray level; A comparator selection circuit 10 sequentially selects each of the comparators 9a, 9b, and 9c and sends the output to the segment driver 5. In the block diagram configured as described above, when an image signal is applied to the comparator 9, if there are n common electrodes 2, the scanning signal is reduced to 1/! The selection order generating circuit 8 operates with the signal frequency-divided by the frequency dividing circuit 7 which divides the frequency into 1, and the gray level of the image signal is compared by the comparator 9a selected by the signal and the signal is "H" or "L".
" is output as a digital signal. This output is a shift clock generated by a shift clock generator 6 that is synchronized with the scanning signal, and is time-divided into segment data l.
It is input to the segment driver 5. Then, the C of the common electrode 2 is controlled by the common driver 3 synchronized with the scanning signal.
When each dot 1 connected to 0M1 is in a driving state, each dot 1 connected to COMI of the common electrode 2 is displayed by outputting segment data 1 from the segment driver 5. Similarly, in synchronization with the next scanning signal, each dot 1 connected to COMI of the common electrode 2 becomes inactive, and each dot 1 connected to C0M2 of the common electrode 2
is in the driving state, the segment data 2 is output from the segment driver 5, thereby changing the C0 of the common electrode 2.
Each driver (1) connected to M2 is displayed.

The common driver 3 in Fig. 6 is synchronized with the scanning signal at the timing shown in the timing chart in Fig. 7 in the following order.
is selected by sequentially driving each dot 1 connected to C0M3 of the common electrode 2 to the dot 1 connected to COMn of the common electrode 2, and outputting the segment data corresponding to each dot from the segment driver 5. Display for one gradation is performed for the comparator 9a.

From the above, one frame, that is, scanning from COMI to C0Mn of the common electrode 2 is required for gray scale display of 1liIi1 minute. In this conventional example, three frames of scanning are required, and the first comparator 9 sequentially scans from the first to the third gradation.
a, by selecting the second comparator 9b and the third comparator 9C and displaying their outputs.

For the first time, each driver is driven at a driving time rate corresponding to the gray level of the image signal, and the gray level of the image for one screen is displayed. In addition to the display method shown in FIG. 6, an active matrix method (not shown) is also known. In this method, a thin film transistor is formed in each dot of a liquid crystal display, and when one image signal voltage is applied to each dot, the OFF resistance between the collector and emitter of the thin film transistor is large. An image is stored in each dot of the liquid crystal until the accumulated image signal voltage is discharged due to a time constant due to the capacitance of the liquid crystal. Therefore, by applying a pulse whose amplitude is modulated by one image signal to each dot, an image with shading can be displayed.

[Problem that the invention seeks to solve]

By the way, in the above-mentioned conventional example, the method of displaying an image with three gradations of light and shade on the dot matrix of the liquid crystal display shown in FIG. is required, which causes the problem that the image flickers.Furthermore, in order to avoid flickering, the display time for one frame must be shortened, and a high frequency is required for the synchronization signal for frame scanning. Therefore, there was a problem in that a liquid crystal display with high-speed response was required.

The active matrix method also has the problem that the product is expensive and it is extremely difficult to manufacture large screens. This invention was made in order to solve these problems, and it is possible to provide high-quality screen display without flickering, and to change the shading of images using a liquid crystal pattern that allows the display to be larger and to provide products at a lower cost. The purpose is to obtain a display method.

[Means to solve the problem]

The method for displaying grayscale images using a liquid crystal pattern according to the present invention involves dividing each dot constituting a dot matrix of a liquid crystal display into two or more different area ratios, and converting each divided element into a digital signal of a desired image signal. Since each dot is displayed in gradation according to the change in the image signal, the conventional method of multiple frame scans can be displayed with a single frame scan.

[Effect]

In this invention, each dot is divided into two or more elements with different area ratios, and each divided element is selectively operated with a digital signal of an image signal via a segment electrode, so that the area of the selected element is When the ratio is large, it is displayed in black, and when the area ratio is small, it is displayed in gray. Furthermore, when none of the elements is driven, it is displayed in white.

Therefore, a desired color tone display according to changes in the selection operation of the elements can be obtained in one frame scan.

〔Example〕

FIG. 1 is a block diagram showing one embodiment of the present invention.
Portions that are the same as or correspond to those of the conventional example shown in the figures are given the same reference numerals and redundant explanations will be omitted.

Y is composed of two or more dots (11) divided by a liquid crystal dot matrix with different area ratios, and in this embodiment, a large hook-shaped element (1) is connected to the large hook-shaped element (11) via an L-shaped partition line (12).
1a and a small rectangular element ttb, and the area ratio of the two large and small elements 11a and llb is approximately 2:1 (see FIG. 2), 13 indicates a segment electrode, 13a is a segment electrode connected to the element 11a, 13b is a segment electrode connected to the element 11b, 14 is a shift clock generator that transmits a shift clock and a sampling signal synchronized with the scanning signal, and 15 is a segment electrode 1.
A segment driver 16 that outputs two types of segment data to 3a and 13b receives the sampling signal, samples the output data of the first comparator 9a, the second comparator 9b, and the third comparator 9C, and outputs the The segment driver 15 connected to the segment electrodes 13a, 13b has large and small elements 11a, l constituting each dot 11.
This is a sampling circuit that can transmit two types of signals, segment data A and segment data B, for driving lb. The segment driver 15 is configured to be able to input the shift clock from the shift clock generator 14 and the latch signal of the scan signal.

Furthermore, the segment data A, the segment data B
is each driver arranged in a matrix according to the scanning signal)
11 can be sequentially scanned. In addition, the outputs of the first comparator 9a, the second comparator 9b, and the third comparator 9C and the segment data A
, segment data B are set as shown in Table 1.

That is, by the combination of rLJ or rHJ of the output signals of the comparators 9a, 9b, 9'c, the output signals segment data A and segment data B of the sampling circuit 16 are rLJ rLJ, rLJ rHJ
, rHJ, rLJ, or rl ("rH"), four types of determined signals can be transmitted.

The operation will be explained below based on the above configuration.

In the block diagram shown in FIG.
When the image signal is input to rHJ, the first comparator 9a, second comparator 9b, and third comparator 90 compare the gray level of the image signal.
Alternatively, the output data of the first comparator 9a, the second comparator 9b, and the third comparator 9C are sampled by the sampling circuit 16 at a timing synchronized with the sample signal, and the segment data A , segment data B is created. Then, by the common driver 3 synchronized with the scanning signal, the COM of the common electrode 2 is
When the elements 11a and flb of each driver) 11 connected to I are in the driving state, segment data A and segment data B are output from the segment driver 14, and the elements 11a and ll connected to COMI of the common electrode 2 are output.
b is driven to display shading. That is, the elements 11a, 1
1b is divided into a large hook-shaped element 11a and a small rectangular element 11b with an area ratio of approximately 2:1 as shown in FIG. As can be seen from the figure, neither element 11a nor llb is driven.

That is, since segment data A is "L" and segment data B is "L", the entire display is white, and when only one small rectangular element flb is driven, the other large hook-shaped element 11a is Since it is not driven, segment data A is “L” and segment data B is rH.
” and the entire screen is displayed in light gray. Furthermore, element 1
When only 1a is driven, that is, segment data A
is "H" and segment data B is "L".

Only the large hook-shaped element 11a is driven, and the small rectangular element 11b is not driven, so the entire display is dark gray.If the pixel elements 11a and 11b are further driven, that is, segment data A and segment data B are Since both are rHJ, the entire image is displayed in black. In this way, at least four shades of gray can be displayed depending on whether or not the pixel elements 11a and llb are driven.

Similarly, C0M2 of common electrode 2 is synchronized with the next scanning signal.
When each dot ll connected to is in the driving state, each signal of segment data A and segment data B is successively outputted from the segment driver 15, and the elements 11a and llb connected to C0M2 of the common electrode 2 of the next stage are output. As described above, a display with shading depending on the image signal can be obtained. Hereinafter, the common driver 3 synchronized with the scanning signal at the timing shown in the timing chart of FIG. As a result, an image with shading for one screen of the liquid crystal dot matrix Y can be displayed. In other words, it is possible to display one screen by scanning one frame.

In the above embodiment, each dot 11 is formed by two elements 11a.
.

Depending on the area ratio of 11b, desired shading can be freely obtained. Furthermore, by dividing each dot 11 into two or more elements, more combinations can be made and the gradation of shading can be increased.

〔Effect of the invention〕

As explained above, this invention divides each dot into two or more elements with different area ratios, so it only takes one frame of scanning to display one screen's worth of shading, which reduces flickering compared to conventional methods. This enables high-quality screen display without any blemishes. In addition, compared to conventional methods, only one frame scan is required, which increases the data processing capacity per unit time.
Since the responsiveness of the display to image values is improved, it is possible to follow rapidly changing images and faithfully reproduce images. Furthermore, by dividing each dot into multiple parts according to the area ratio, it is possible to obtain the desired gradation of light and shade, providing excellent image quality with excellent resolution and clarity. can be manufactured at low cost.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a structural diagram of each dot showing an embodiment of the invention, Fig. 3 is a diagram showing the relationship between the ratio of area to be driven and the density level, Figure 4 is a timing chart diagram of Figure 1, Figure 5 is a diagram showing the relationship between driving time ratio and gray level, Figure 6 is a block diagram showing a conventional example, and Figure 7 is a timing chart diagram of Figure 6. be. In the figure, 2 is a common electrode, 3 is a common driver,
9a is a first comparator, and 9b is a second comparator. 9C is a third comparator, lla is a hook-shaped element, llb is a rectangular element, 12 is a dividing line, 13a is a segment electrode connected to lla, 13b is a segment electrode connected to llb, 14 is a shift clock generator, 15 is a segment driver, 16 is a sampling circuit, and Y is a liquid crystal dot matrix.

Claims (2)

[Claims] (1) Each dot constituting the dot matrix of a liquid crystal display is divided into two or more elements with different area ratios, and each divided element is processed with a digital signal of the desired image signal to separate each dot. A method for displaying an image in gradation using a liquid crystal pattern, characterized in that the image is displayed in gradation in accordance with changes in the image signal. (2) Each dot constituting the dot matrix of the liquid crystal display is divided into a large hook-shaped element and a small rectangular element through an L-shaped dividing line, and the area ratio of the two large and small elements is 2. A method for displaying shading of an image using a liquid crystal pattern according to claim 1, wherein the ratio is approximately 2:1.