JP2844192B2 - Liquid crystal display - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a liquid crystal display device. [Summary of the Invention] The present invention relates to a dot matrix type liquid crystal display, in which the frequency of a reference clock oscillator for generating a data transfer clock is adjusted by correcting the viewing angle in order to correct a difference in luminance due to a difference in viewing angle when viewing the liquid crystal display. By changing the selection time of the scanning electrode by changing it according to the time, the selection time is shortened on the low viewing angle side, and the selection time is lengthened on the high viewing angle side, so that the difference in brightness due to the difference in viewing angle is corrected and uniform. This is to display. [Prior art] A conventional dot matrix type liquid crystal display (hereinafter, LC)
FIG. 1 shows an example of a drive circuit configuration (abbreviated as D), and FIG. 2 shows a timing chart thereof. FIG. 1 shows an oscillator 101 for generating a reference clock.
Each control signal is made by the display control circuit of 103 based on. FIG. 2 shows a timing chart of the control signal. The control signal is input to the signal electrode driver shown in FIG. 104 to generate the signal electrode side drive waveform shown in FIG. 124, and the scan electrode driver shown in FIG.
The scan electrode side drive waveform shown in FIG. Each pixel is turned on by applying this drive waveform to each electrode of the LCD,
Turn off the light. [Problems and Object to be Solved by the Invention] In the case of the driving described above, the selection time of each scanning electrode indicated by T21, T22, and T23 in FIG. 2 is all constant. Therefore, when viewing a large LCD at an optimal clear viewing position as shown in FIG. 3, there is a large difference between the viewing angle on the scanning electrode in FIG. 3 and the viewing angle on the scanning electrode in FIG. Yes, 3
There is a difference in luminance between the pixel on the 02 scan electrode and the pixel on the 303 scan electrode. [Means for Solving the Problems] In the liquid crystal display device of the present invention, liquid crystal is sandwiched between one substrate on which a plurality of scanning electrodes are formed and the other substrate on which a plurality of signal electrodes are formed. In the liquid crystal display device, a constant voltage is applied to the plurality of scan electrodes during a selection period, and the plurality of scan electrodes are made uniform so that display characteristics of an entire display screen of the liquid crystal display device are uniformed. The selection time of the voltage applied to the liquid crystal display device is set to be gradually longer from the low viewing angle side to the high viewing angle side of the liquid crystal display device. [Operation] By performing the driving method as described above, a difference in LCD luminance due to a difference in viewing angle can be corrected, and uniform display on the LCD can be achieved. [Example] An example of the present invention will be described below, and will be described in detail. FIG. 4 shows an example of the configuration of an LCD drive circuit capable of changing the selection time of the scanning electrodes. FIGS. 5 and 6 are timing charts of the drive waveforms. FIG. 401 is a voltage controlled oscillator. This oscillator can change the oscillation frequency to a high frequency when the voltage is high and to a low frequency when the voltage is low by the output voltage of the voltage control circuit 403. As can be seen from Fig. 3, LC
When viewed from the optimum clear viewing position of D, the viewing angle differs depending on the position of the scanning electrode, and the brightness differs. In order to correct this difference, while the scan electrode on the low viewing angle side as shown in FIG. 3 is selected, the voltage in FIG. 4 is increased to increase the frequency of the output 411 of the oscillator. In synchronization with this 411 reference clock, each control signal 412, 413, 414, 415, 416,
Since 417, 418, 425, and 426 operate, the output signal 421 of the scan electrode driver outputs the drive waveform shown in FIG. 421, and the scan electrode selection time T61 is the shortest among the scan electrode selection times. Next, when the scan electrode 422 in FIG. 4 is selected, the voltage at 419 is slightly lower than at the time of selection of 421, and the frequency of the reference clock at 411 is also lower. Thus, the electrode selection time T62 in FIG. 422 is slightly longer than the electrode selection time T61 in 421. By such an operation, as the viewing angle with respect to the LCD becomes higher, the voltage of FIG. 419 is reduced as shown in FIG. 419, and the frequency of the reference clock of FIG. As a result, the selection time of the scanning electrode also changes, and as the viewing angle increases, the selection time gradually increases. FIG. 42
Reference numeral 3 denotes an electrode at the highest viewing angle position, and its driving waveform is the waveform 423 in FIG. As can be seen from this timing chart, when the electrode shown in FIG. 423 is selected, the voltage at 419 is the lowest and the frequency of the reference clock at 411 is also the lowest. Thus, the electrode selection time T63 in FIG. 423 becomes the longest selection time among the scanning electrodes. When the selection of the 423 electrodes is completed, the voltage of 419 also increases at the timing of the signal of FIG. At this time, the scanning electrode of FIG. 4 is selected and the selection time is the shortest. Although the above embodiment is a circuit for varying the frequency of the reference clock using a voltage-controlled oscillator, there are other methods of varying the frequency. In the present invention, the method of generating the reference clock shown in FIG. Such a method may be employed, in which the selection time of the scan electrode is changed by changing the reference clock. [Effect] The present invention is a driving method in which a constant voltage is applied to a plurality of scan electrodes during a selection period, and it is not necessary to set many voltage levels according to the scan electrodes. Therefore,
There is no need to provide a complicated circuit. Furthermore, by gradually setting the selection time of the voltage applied to the plurality of scan electrodes from the low viewing angle side to the high viewing angle side of the liquid crystal display device, the display characteristics of the entire display screen of the liquid crystal display device are uniformed, The viewing angle characteristics of the liquid crystal display device can be improved. In other words, the present invention provides a liquid crystal display device having a simple circuit configuration and uniform display characteristics by changing the selection time for each scanning electrode.

[Brief description of the drawings] FIG. 1 is a block diagram of a conventional LCD drive circuit. 101: Oscillator 102: Frame memory 103: Display control circuit 104: Signal electrode driver 105: Scan electrode driver 106: Dot matrix liquid crystal display 111: Reference clock 112: Signal electrode data transfer clock 113: Scan electrode data transfer clock 114: Data latch 115: Scan electrode data 116: Frame signal for AC drive 117: Signal electrode data 118: Address signal 119: Display data 121,122,123: Scan electrode 124: Signal electrode FIG. 2 is a timing chart of a conventional LCD drive waveform. 111: Reference clock 112: Signal electrode data transfer clock 113: Scan electrode signal data transfer clock 114: Data latch 115: Scan electrode data 116: Frame signal for AC drive 117: Signal electrode data 121, 122, 123: Scan electrode drive waveform 124: Signal electrode drive waveform FIG. 3 is a sectional view of the LCD. 301: Dot matrix liquid crystal display 302,303: Scan electrode 304: Viewpoint to see the display 305,306: viewing angle FIG. 4 is a block diagram of an LCD drive circuit. 401: Voltage controlled oscillator 402: Frame memory 403: Voltage control circuit 404: Display control circuit 405: Signal electrode driver 406: Scan electrode driver 407: Dot matrix liquid crystal display 411: Reference clock 412: Signal electrode data transfer clock 413: Scan electrode data transfer clock 414: Data latch 415: Scan electrode data 416: Frame signal for AC drive 417: Signal electrode data 418: Voltage control signal 419: Frequency control signal 421,422,423: scanning electrode 424: Signal electrode 425: Address signal 426: Display data FIG. 5, FIG. 6... LCD drive waveform timing chart. 411: Reference clock 412: Signal electrode data transfer clock 413: Scan electrode data transfer clock 414: Data latch 415: Scan electrode data 416: Frame signal for AC drive 417: Signal electrode data 418: Voltage control signal 419: Frequency control signal 421,422,423: Scan electrode drive waveform 424: Signal electrode drive waveform

Claims (1)

(57) [Claims] In a liquid crystal display device in which liquid crystal is sandwiched between one substrate on which a plurality of scan electrodes are formed and the other substrate on which a plurality of signal electrodes are formed, the plurality of scan electrodes are mutually connected during a selection period. A constant voltage is applied, and the selection time of the voltage applied to the plurality of scanning electrodes is set from the low viewing angle side of the liquid crystal display device so as to uniform the display characteristics of the entire display screen of the liquid crystal display device. A liquid crystal display device characterized in that the liquid crystal display device is gradually set to a longer viewing angle side.