JPS5997191A - Driving of display unit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a display device using a liquid crystal (LCD) and an electroluminescent lamp (KL), and particularly to a method for driving an LCD-EL matrix display system.

Background technologyCathode ray tube (CRT), liquid crystal (LCD), light emitting diode (LED), electrochromic (ECD)
), electroluminescence (KL) is a type of display device, and electroluminescent lamp display devices (hereinafter referred to as EL devices) and liquid crystal display devices (hereinafter referred to as liquid crystal devices) are thin, lightweight, low voltage drive, and low consumption. It is advantageous in terms of electricity. In this type of denomination chair, a large number of stripe-like electrodes are provided in the X-Y direction, and an image can be formed by pixels at the intersections of the X-Y matrix and displayed dynamically. It is used as a so-called dynamic display device, in which each stripe electrode is sequentially scanned and driven in an XY matrix.

By the way, in the matrix display method using only EL or liquid crystal display, the display was not performed.

In order to eliminate such losstalk, the applicant has developed a liquid crystal device (LCD) and an electroluminescent device (IIEL).
He proposed an ``image display device'' (Japanese Patent Application Laid-Open No. 57-61381) that shows IJ Lux by laminating X-Y masonry (XY ma). As disclosed in Japanese Patent Laid-Open No. 57-61381, this image display device is constructed by stacking a liquid crystal display panel (LCD) and an EL display panel, and synchronously sends drive signals to each striped electrode pattern. (Supplied to Ma)
This shows IJ socks. However, in the scanning of the drive signal, LoD does not immediately obtain the desired transmittance when the signal starts being supplied thereto, and there is some delay in the rise of the transmittance characteristic. This delay is noticeable compared to the rise of the light emission characteristics when the signal is supplied to KL, and Log)
X display of the part where a signal is continuously supplied (horizontal axis) that matches the direction of the stripe-shaped electrode of the LCD, and display of the part (vertical axis) where a signal is intermittently supplied orthogonal to the stripe-shaped electrode of the LCD Even under the same EL backlight, the emitted light intensity differs, causing blurring and worsening the contrast of the image.

DISCLOSURE OF THE INVENTION Therefore, the present invention has been proposed in view of the above two points.
The object of the present invention is to provide a new and improved driving method in a matrix display system in which a liquid crystal device (LCD) and an electroluminescent device (KL) are stacked.

According to the present invention, in a matrix display method in which a liquid crystal device and an electroluminescent device, each having a large number of stripe electrodes, are stacked and a predetermined drive signal is supplied to form an image, the electroluminescent device (mr,) side A driving method is disclosed in which the timing of supply start of the driving signal to the liquid crystal device (LCD) is completely delayed from that of the driving signal to the liquid crystal device (LCD) side. That is, in a dynamic display device that uses EL as a backlight of an LCD and displays a matrix using the Nyatta effect of the LCD, the L
This method was proposed focusing on the difference in responsiveness between OD and EL, and the time lag at the start of driving the LCD is delayed in the start timing of signal supply to KL to match the EL light emission LOD transmission. Such control of the EL lighting signal with respect to the LOD opening/closing signal prevents blurring, unevenness, and contrast reduction in image display and enables good image reproduction.

Therefore, the driving method of the present invention for the LOD-KL combination IJ hook display device has great practical value.

BEST MODE FOR CARRYING OUT THE INVENTION FIG. 1 shows an LCD-E to which the driving method according to the present invention is applied.
FIG. 2 is a perspective view of an LLCD display device. This display device M (H) consists of a liquid crystal device (liquid crystal device) having a large number of striped electrodes (with holes) in the horizontal axis direction (X direction) and a large number of stripe shaped electrodes (having holes) in the vertical axis direction (Y direction). Electroluminescent devices (composed of stacked layers).Each device (
1'4 (each having a common electrode (not shown)) is used as an X-Y matrix display device that prevents crosstalk as disclosed in Japanese Patent Laid-Open No. 57-61381. .It is an LCD display that uses so-called KL as a backlight.

This display device (1 (9) is dynamically operated by electroluminescent device (1) striped lightning, pole (13)
1 is given a scanning drive signal (161), and the liquid crystal device (
A display drive signal (
This is done by adding 151. These scanning drive signals (16
1 and the display drive signal 05) are used to form and display an IJ wax image, but in conventional drive systems, both signals are supplied synchronously, and the displayed image I20) is as shown in Figure 2. Shading appeared in the horizontal axis display section (21) and the vertical axis display section), causing unevenness, blurring, and poor contrast.

In other words, since the display effect cannot be obtained immediately after the application of the drive signal in the liquid crystal device (uniform X-axis scanning), the horizontal axis display section (2Q is dark (
In contrast, the vertical axis display section ρ) to which the signal is intermittently applied in the vertical axis direction is displayed faintly (weakly). Here, (171 (+8) is a switching control device that supplies a drive signal in the X direction and a switching control device that supplies a drive signal in the Y direction, respectively, and receives a control signal from the clock device (19). It is operated.

The synchronous supply method of drive signals causes undesirable unevenness in shading and poor contrast in dynamic display images, but this is influenced by the rise in the transmission characteristics of the liquid crystal display (chair) used, and the rise in the transmission characteristics curve. Even in the case of a liquid crystal device of a flat speed drive type having a steep speed, it reaches a complete operating state after about 1 m5 ec from the start of supply of a drive signal, and in the case of a normal type, this is 5) y1m to lom alternating. From this perspective, attention has been focused on the drive signal control method.
An improved drive system is presented here. That is, L
KL in CD-KL matrix display device
This is delayed supply of the EL drive signal with respect to the LCD drive signal, and the application of the EL drive signal is started at a predetermined timing after the LCD drive signal is applied. This timing delay preferably regulates the emissive portion of the luminescent characteristic of the electroluminescent device to prevent display at the rising portion of the transmissive characteristic of the liquid crystal device. Specifically, the start point of supplying the drive signal to the electroluminescent device is delayed within the time lag of the rising portion due to the transmission characteristics of the liquid crystal device used.

FIG. 3 is a display image obtained by the driving method of the present invention,
It is shown in contrast to FIG. In the present invention, an image (20) having a constant density or contrast is reproduced in the vertical and horizontal image portions (23) P4) in the X-Y direction, so that bleeding, unevenness, and contrast are not worsened. Therefore, a clear and desired display can be achieved.

FIG. 4 is a characteristic diagram of each signal in the driving method according to the present invention. FIG. 4(a) shows a reference signal generated by the clock device (19), which is an IKHz clock signal. Figures 4 (bl and c) show the ON-OFF state of the drive signal for a liquid crystal device (1) and the transmission characteristics (changes in light amount) indicating the accompanying display operation.Furthermore, Figure 4F
dl and (e) show the ON-OFF state of the drive signal of the electroluminescent device (14) and the light emission characteristics associated therewith.

The point to note here is that the amount of transmitted light reaches the desired amount after a rising period (tl) after the start of supply within the ON period of the LCD drive signal, but the KL drive signal is turned ON at the same time]105 The purpose is to obtain luminescence. That is, L.O.D.
This is because the lighting of KL, which serves as a backlight light source, is regulated over the period of time lag (tl) of operation. As a result,
'LOD-EL A uniform display of images reproduced on the screen of the EL matrix display device is achieved. Further, such a method for driving a display device can be easily programmed using a personal computer, and when used in combination with this method, it is of high practical value as it helps to improve the display device.

[Brief explanation of the drawing]

Figure 1 shows an LOD-ELX to which the driving method of the present invention is applied.
-A perspective view of the Y matrix display device, FIG. 2 is a display image diagram obtained when driven by the conventional method, FIG. 3 is a display image diagram obtained when driven by the method of the present invention, and FIG. FIG. 3 is a signal characteristic diagram in the driving method of the present invention. (1 (1...LOD〒ELX-Y Matrix Distributor (11) (1")... Striped electrode (11
......Liquid crystal device (14)......Electroluminescent device (151 (16)
)... Drive signal (171 (fill...
・Switching control device-10-

Claims (1)

[Claims] , ρ 1) In an X-Y matrix display method in which a liquid crystal device and an electroluminescent device each having a large number of striped electrodes are stacked and a predetermined drive signal is supplied to each electrode to form an image. . A method for driving a display device, characterized in that the start timing of the supply of the drive signal to the electroluminescent device is delayed compared to the drive signal to the liquid crystal device. 2) The method for driving a display device according to claim 1, wherein the timing delay is set within a period of a rise time lag during driving of the liquid crystal device to achieve uniform Ha contrast.