JPH0685113B2 - Matrix liquid crystal display panel - Google Patents

Description

The present invention relates to an improvement in a liquid crystal display panel in which a liquid crystal layer is interposed between a substrate on which switch elements are integrated and a transparent substrate provided with a transparent electrode on one side. The purpose of the reduction is to improve the reliability of the display device.

Hereinafter, description will be given with reference to the drawings.

A conventional liquid crystal display panel using a MOS transistor is constructed as shown in FIG. FIG. 1 is a connection diagram showing a configuration of a conventional display panel. The unit pixel is composed of the MOS transistor 1, the liquid crystal cell 2, and the charge storage capacitor 3. For example, when an ON signal is applied to the scan electrode Xi, the MOS transistor 1 is turned on, and the capacitor 3 is charged from the video signal electrode Yi through the transistor 1. Even if the OFF signal is applied to the scan electrodes, the liquid crystal layer 2 is in the ON state while the charge of the capacitor 3 applies the voltage to the liquid crystal layer 2, and the optical characteristics of the liquid crystal layer 2 are controlled by the video signal. As shown in FIG. 1, unit pixels are arranged in a matrix form, and moving image display can be obtained by line scanning drive. In order to operate this display panel, it is necessary to connect an external drive circuit to the scanning electrodes and the video signal electrodes. When the unit pixels are arranged in a matrix of M rows and N columns, assuming that there are M scanning electrodes and N video signal electrodes, there will be (M + N) external connection terminals. At least M = 2 for a display similar to a CRT
It is said that about 00 and N = 600 are necessary. As a result, the number of external connection terminals becomes 800, and the size of the display device becomes larger due to the increase in the bonding pad area, the cost increase due to the large number of bondings, and the decrease in reliability are obstacles to practical use. The present invention provides a liquid crystal display panel having a low cost and high reliability by reducing the number of video signal electrodes by disposing a switch circuit having a decoding function in each pixel. Hereinafter, description will be given based on embodiments with reference to the drawings.

Embodiment 1 FIG. 2 is a connection diagram showing the configuration of the display panel of the present invention.

A switching circuit 41 is formed by serially forming two MOS transistors as switching elements for each pixel. The gates of the MOS transistors are connected to Xi, ₁ , Xi, ₂ and the signal inverted by the inverter 10 as shown in the figure.

The signal of the video signal electrode Yi is transmitted to one of the liquid crystal cells 4, 6, and 8 depending on the signal applied to the scan electrodes Xi, ₁ and Xi, ₂ . That is, a single video signal electrode can selectively transmit a signal to a liquid crystal cell having a width of 3 dots.
Reference numerals 5, 7, and 9 are capacitors.

Embodiment 2 FIG. 3 is a connection diagram showing the configuration of a display panel in another embodiment of the present invention.

Enhancement type as a switch element for each pixel
MOS transistor 17 and depletion type MOS transistor
Two of 18 are formed in series to form a switch circuit 42. In the present embodiment, since the depletion type and the enhancement type are used in combination, the negation signal is not required and the inverter 10 in the first embodiment is not required. Similar to the first embodiment, the image signal is selectively applied to one of the three pixels by the combination of the potentials of the scan electrodes Xi, ₁ and Xi, ₂ . It goes without saying that the n-type enhancement MOS transistor and the P-type depletion MOS transistor have the same function in the case of combination.

As described above, the present invention realizes a low-cost and highly reliable liquid crystal display panel by arranging a switch circuit having a decoding function in each pixel to reduce the number of video signal electrodes. In particular, the present invention is effective for an RGB color system panel and a surface distribution gradation system panel.

[Brief description of drawings]

FIG. 1 is a connection diagram showing a configuration of a conventional liquid crystal display panel using a MOS transistor, and FIGS. 2 and 3 are connection diagrams showing a configuration of a display panel according to an embodiment of the present invention. 1 ... MOS transistor, 2 ... liquid crystal layer, 41, 42 ... switch circuit, 10 ... inverter, 17 ... enhancement type MOS transistor, 18 ... depletion type MOS transistor.

Claims (2)

[Claims] 1. A matrix liquid crystal display panel in which a large number of pixel columns each including a liquid crystal layer and a switch circuit for driving the liquid crystal layer are provided, and each pixel column is selectively driven by a scanning electrode and a video signal electrode. Divide into multiple groups consisting of multiple pixels, share the video signal electrode corresponding to each pixel in each group, and configure the switch circuit of each pixel by connecting multiple switch elements in series. Correspondingly, a scan electrode for selecting the switch element is provided,
A matrix liquid crystal display panel characterized by simultaneously selecting a plurality of switch elements corresponding to each pixel for each group and sequentially driving each pixel. 2. An enhancement type MOS transistor and a depletion type MOS transistor are used as a plurality of switch elements constituting the switch circuit, and the switch circuit of each pixel in the group is at least one of the switch circuits of other pixels. The matrix liquid crystal display panel according to claim 1, wherein the transistors corresponding to the common scan electrodes are of different types.