JPH0213989A - Control of display device - Google Patents

Abstract

PURPOSE: To prevent stripes due to electric discharging of pixels which are not controlled from appearing on a screen by providing pixels and nonlinear prepositional switching elements which are arranged in matrix, and switching the plus/minus sign of a difference voltage plural times in a specific period. CONSTITUTION: A resistance 8 which depends upon a voltage and a capacitor 9 which is formed of an electrode of a pixel are connected to each intersection and the resistance 8 is formed of a nonlinear prepositional switching element which turns on with a specific voltage. Signals are supplied through conductors 1-7 so as to control and charge the individual pixels selectively to apply a difference voltage of corresponding level to pixels to be controlled and a low voltage to other pixels. Then the plus/minus sign of the difference voltage is switched many times in the specific period. Consequently, the electrically charged state of the pixels which are not controlled is held and additional spurious radiation can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a method in which a row multiplexed signal is applied to the conductors forming the rows of a matrix, a column multiplexed signal is applied to the conductors forming the columns of said matrix, and one The pixels of the row are simultaneously
The pixels, which are each assigned to a column, are controlled one after the other in a predetermined period, the control of each said pixel depending on the respective difference between the row multiplex signal and the column multiplex signal. The present invention relates to a display device control method having the pixels arranged in a matrix and a nonlinear n-position switching element, which may or may not be performed.

In the prior art, for example in these known methods for controlling display devices with liquid crystal elements, nonlinear elements are connected upstream of the individual A electrodes forming the pixels. These nonlinear elements have as high a resistance value as possible when the voltage is low, and conduct when the voltage is high. One example of these devices is the so-called M1~ device in which an oxide layer is provided between two metal layers σ.

The role of these non-linear elements is to allow the capacitor formed by the pixel's electrodes to charge when the pixel is controlled, and to allow the pixel to maintain its charging state while other painters are controlled. The goal is to make it possible to retain the However, in known methods, uncontrolled pixels are treated while other pixels are controlled.
A voltage of opposite polarity is applied, which is lower than the control power voltage, but because the non-linear element has residual conduction capability, it discharges the uncontrolled pixel. As a result of this discharge, stripes appear on the screen that run in the column direction and are dependent on the respective image content.

Problems to be Solved by the Invention An object of the present invention is to provide a method for controlling a display device having pixels arranged in a matrix and a nonlinear front switching element, which can avoid the above drawbacks. .

1. Means for Solving the Problems The method of the present invention is characterized in that the positive and negative signs of the differential voltage 1 are switched multiple times within a predetermined period. In this case, this sign change is advantageously carried out in a clock-controlled manner every time a row is changed over. However, it is also possible to change the sign every time a line has changed footpaths a small number of times.

It is known to reverse the polarity of the voltage after controlling all pixels, ie, after writing an image, to obtain control without applying a DC voltage, but this method does not solve the above problem.

Effects of the Invention According to the present invention, while a certain pixel is being controlled,
The state of charge of uncontrolled pixels is approximately maintained. No additional high frequency spectral components, which may generate additional spurious emissions, are generated using the method of the invention.

In one advantageous embodiment, the method according to the invention is carried out by, in addition to switching the positive and negative signs row by row, at the transition from one predetermined time period to another predetermined time period, by switching the positive and negative signs for DC voltage compensation. It is combined with known methods.

EXAMPLES Next, the present invention will be explained in detail based on examples and with reference to the drawings. Identical parts in different figures are designated by the same numbers. The expressions row and column are used herein without reference to spatial arrangement; these expressions are determined solely by the control type.

@1 Figure shows a part of a display device having pixels.

Column conductors 1.2, 3.4 and row conductors 5, 6.7 are used to control the pixels. A voltage-dependent resistor 8 and a capacitor 9 formed by the electrodes of the respective pixel are connected to each crossing point. When a voltage is applied to a certain capacitor 9, the pixel changes its color, for example becoming black. The voltage-dependent resistor 8 is preferably formed by an MIM element which is conductive at a given voltage. Therefore, in order to selectively control and charge individual pixels, a signal is supplied via the conductors 1 to 7, so that a voltage difference of a corresponding magnitude is applied to the pixels to be controlled, and to the pixels not to be controlled. Apply a voltage lower than this.

In the following explanation based on FIG. 1, the MIM element 8 is conductive at a normalized I value of 2;
The capacitor is then charged, whereas the MIM element is non-conducting if the differential voltage is less than the value 2. FIG. 1 shows three clock periods Tl, T2 . The changes during T3 are shown, where the voltages at conductors 1 to 7 during these three clock periods are shown. During the first clock period, a voltage of 2. O,
0 and 2 are applied. A voltage 0 is applied to the horizontal conductor 5, whereas a voltage 1 is applied to the horizontal conductor 6.7.

Correspondingly, during the first tarok cycle TI, pixel 1
The voltage at 1 and 41 is l, and at all other pixels the differential voltage is less than l. Therefore, pixel 11
and 41 are controlled, that is, their capacitors 9 are charged as indicated by diagonal lines in the figure.

In the next clock period T2, the voltages supplied to conductors l to 4 have the same value, whereas conductors 5 and 7 are applied with voltage l, and conductor 6 is connected to voltage OV. . In this clock period, pixels 12 and 42
is controlled. In the third clock period T3, voltage 1 is applied to conductors 5 and 6, and conductor 7 is connected to voltage OV. At that time, voltage 2 is applied to all vertical conductors 1 to 4, so pixels 13, 23, 33.4
3 is controlled. The pixels that are controlled in each case are indicated by diagonal lines on the capacitors.

After all rows have been controlled, a new cycle begins on the first row. This predetermined period will be referred to below as picture period, a term from television technology.

FIG. 2 shows the change in the voltage Uxy applied to one pixel in two periods in the case of control in a known manner. In FIG. 2a, the pixel corresponding to the voltage change is connected, and the other pixels in the column are cut off. In the case shown in FIG. 2, we start from the fact that all pixels of the column in question are connected. In the period between 0 and tl, a voltage of value 19 is applied to the pixel, so that the MIM element becomes conductive and the capacitor is charged to the voltage Ulc indicated by the diagonal line.

Between times tl and tn, the other pixels of the column in question are controlled, with a voltage of -3.5 V being applied to the pixels of row l. As a result, the voltage Ulc drops through the residual conducting capacity of the MIM element, and thus at the end of the period from to to tn (picture period) the voltage of the pixel and thus the contrast is smaller than at the beginning of the picture period.

In the next image cycle, during the period tn to t2n, control of the opposite polarity is performed, but the resulting contrast reduction is similar to that described above.

If other pixels in the column are connected, t
Since a voltage greater than +3.5V is generated during the period from 1 to tn, the voltage Ulc hardly drops.

FIG. 3a shows the voltages when the other pixels of column l are cut off, and FIG. 3a shows the voltages when all the pixels of column I are connected.

3.5 for the relevant pixel during the period from tl to tn.
A square waveform voltage between V and -3.5 cm is applied. There is no discernible difference between case a) and case b) other than the fact that the phase is shifted. Therefore, the discharge of the pixel shown in FIGS. 2a and 2b is substantially independent of the control of the other pixels in the column.

Furthermore, the drop in voltage Ulc is not very large, because t
This is because the voltage at the pixel is negative only during part of the period between l and tn.

Viewed in the column direction, each second or every other pixel is connected and the pixels between them are cut off, so that even when using the method of the invention, the discharge shown in FIG. 2 does not occur. It is certainly possible to do so. However, in information represented by a point matrix display device, the probability that such image content will occur is usually very small, or its occurrence is not taken into account from the beginning.

Figures 2a and 2s and 3a and 3s show the voltage at one pixel that occurs due to the difference between the voltages on the intersecting conductors. Figures 4a-e and 5
Figures a-e show the voltage on the conductor 1 and the differential voltages resulting from this 1 voltage in several pixels.・
4 shows a known method, and FIG. 5 shows a method according to the invention. The signals shown in a, 1, and C, respectively, are connected to four conductors in the row direction, for example, conductors 1, 2, and 3.
(Figure 1). The two multiplexed signals applied to the column conductors are d.

It is shown in e.

Other diagrams show the differential voltages resulting from the column and row multiplex signals at individually located warp pixels. Therefore, for example, while the pixels in row 1, column I are connected, the voltage H in the pixels in column I in rows 2 and 3 has not reached the voltage required for connection. Column 2
The pixel in row 2 out of the three pixels in (connected, the other two pixels are blocked).

It can be seen from the diagram in a that in the illustrated example only the pixels in column I are connected, while the pixels in columns 2 to N are blocked. A similar operation is performed with the opposite sign. The synchronization of the two images is indicated together in FIGS. 4 and 5 by the period duration T.

From FIG. 5 as well as from FIG. 3, the method of the present invention]
Therefore, the voltage change in one pixel is
is independent of the state of other pixels in the column.
I understand.

FIG. 6 shows a control device for controlling a liquid crystal display device 51 including MIM elements, and this liquid crystal display device 51 is provided with 128 rows and 160 columns. This is 204
This corresponds to 80 pixels.

The individual components of the apparatus of FIG. 6 are well known and a detailed description thereof is not necessary for understanding the invention. A controller 52 commercially available under the name HD61830 is used to control the time change of the control signal. The voltage to be applied to the conductors in each individual period is generated in a voltage supply unit 53. Switching signals from controller 52 are provided to row drivers 54 and 55 and column drivers 56 and 57. These row and column drivers are commercially available.

The voltages Vl, V2 . generated by the voltage supply unit 53 are controlled by the switching signal. V5. V6 is the row driver 54
．． 55 as a multiplexed signal in accordance with FIG. Multiple signals for column conductors are column drivers 56.57
The voltages vl, v2. V3. Generated from V4. A crystal oscillator 58 with a frequency of 1.5 MHz is used to generate the clock signal for the controller 52.

Data generated by controller 52 during program operations can be temporarily stored in RAM 59.

The main processing unit (
A main processing unit (MPU) 60 is provided, and the main processing unit 60 is connected to the controller 52 via corresponding data lines, control lines, and an address decoder 61.

Various commands such as start, stop, positive, negative, reset, etc. are supplied to the main processing unit 60 through the input unit 62.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a part of a display device having pixels arranged in a matrix, FIG. 2 is a waveform diagram of a pixel control voltage using a known method, and FIG. 3 is a pixel control voltage using the method of the present invention. Voltage waveform diagram; FIG. 4 is another waveform diagram in the known method; fifth factor is another waveform diagram in the method of the invention; FIG. 6 is a block circuit of a circuit arrangement for carrying out the method of the invention. It is a diagram. 1 to 7... Conductor, 9... Capacitor, 51... Liquid crystal display device, 52... Controller, 53... Voltage supply unit, 54.55... Row driver, 56.57-・
・Column driver, 58...Crystal oscillator, 59...RA
M, 60... Main processing unit, 61... Address decoder, 62... Input unit T2 2 0 0 2
T3 2 2 2 2
− ■ ;;; stone ω 1

Claims (1)

[Claims] 1. A row multiplex signal is applied to the conductors forming the rows of the matrix, a column multiplex signal is applied to the conductors forming the columns of the matrix, and the pixels of each row are simultaneously the pixels assigned to the two columns are controlled one after the other within a predetermined period, the control of each said pixel depending on the respective difference between the row multiplexed signal and the column multiplexed signal; or not performed, in the display device control method having the pixels arranged in a matrix and a nonlinear front switching element, the sign of the difference is switched many times within the predetermined period. A display device control method characterized by: 2. The display device control method according to claim 1, wherein the switching between the positive and negative signs is carried out under clock control every time the rows are incremented. 3. The display device control method according to claim 1, wherein the switching of the positive and negative signs is performed every time the row increments are switched several times. 4. A claim characterized in that, in addition to switching the positive and negative signs for each row at the time of transition from a certain predetermined period to another predetermined period, switching of the positive and negative signs is performed for DC voltage compensation. 4. The display device control method according to any one of items 1 to 3.