JPH043023A - Liquid crystal display device - 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 [Object of the Invention] (Industrial Application Field) The present invention relates to an active matrix type liquid crystal display device, and particularly to a liquid crystal display device driven by an interlaced scanning method.

(Prior Art) Liquid crystal display devices are often used in display sections of electronic devices because of their small size and low power consumption. In particular, active matrix displays, in which switch elements are arranged in a matrix and liquid crystals are directly driven by switches, are attracting attention because they can display extremely fine images.

On the other hand, as a scanning method for a display screen, an interlace scanning method is generally used in which scanning is divided into an even number scan and an odd number scan in order to increase the number of scans and reduce flickering of the image.

Conventionally, when displaying an interlaced scanning video signal using an active matrix liquid crystal display device, a display device having the configuration shown in FIG. 3 has been used.

In the figure, 1 indicates a liquid crystal display panel. This liquid crystal display panel 1 has a pair of transparent substrates, and liquid crystal is sealed between these transparent substrates. One of these transparent substrates is provided with a grounded transparent common electrode. On the other substrate, scanning electrodes Y1, Y2, .
... Y2O and signal electrodes X1, X2, ...
Xm are arranged orthogonal to each other. Scanning electrode Y1, Y
2,... Y2O and signal electrodes X1, X2,...
... At each intersection with Xm, a switch element S1 made of a thin film transistor is provided.

Furthermore, since the driving is performed using an interlaced scanning method, the scanning electrodes Y1, Y2, . . . Y2O are replaced by the odd scanning electrodes Y1, Y3, . , .

The odd scan electrodes are connected to be driven by an odd scan electrode drive circuit 2, and the even scan electrodes are connected to be driven by an even scan electrode drive circuit 3.

Note that 4 is a signal electrode drive circuit that applies a voltage to the signal electrode, 5 is a video signal, 6 is a horizontal/vertical synchronizing signal, and 7 is an odd scan electrode drive circuit 2, an even scan electrode drive circuit 3, and a signal electrode drive circuit 4. , Dl is the liquid crystal display pixel, Ll is the liquid crystal of the liquid crystal display pixel D1, C
1 is a capacitor that holds the voltage applied between the electrodes of the liquid crystal display pixel D1. Then, the video signal 5 is input to the signal electrode drive circuit 4, and the horizontal/vertical synchronization signal 7 is input to the timing control circuit 6.

Timing control circuit 6 based on horizontal/vertical synchronization signal 7
In one frame period, during the odd frame period, the odd scan electrode drive circuit 2 applies sequential scan pulses to the odd scan electrodes, and during the even frame period, the even scan electrode drive circuit 3 applies the scan pulses to the even scan electrodes. A scanning pulse is applied sequentially.

By applying a scanning pulse to the scanning electrode, the switching element S1 of the thin film transistor becomes conductive.

On the other hand, according to the input of the video signal 5 and the control signal from the timing control circuit 6, a signal electrode drive voltage is applied to Xl, X2, . . . A driving voltage is applied to the corresponding liquid crystal display pixel D1 on the scanning electrode to which the scanning pulse is applied, and an image is displayed on the liquid crystal display panel 1.

Incidentally, in such a liquid crystal display device, it is desirable that the number of parts be as small as possible from the viewpoint of reducing manufacturing costs.

However, in the liquid crystal display device shown in FIG. 3, the number of terminals taken out from the liquid crystal display panel 1 is large, causing high costs.

(Problems to be Solved by the Invention) As described above, the conventional liquid crystal display device has problems such as high cost and large size due to the large number of terminals taken out from the liquid crystal display panel.

The present invention has been made to solve these conventional drawbacks, and aims to reduce the number of terminals taken out from a liquid crystal display panel, thereby providing a liquid crystal display device that is smaller in size and lower in cost. do.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides scanning electrodes consisting of a plurality of odd-numbered electrodes and a plurality of even-numbered electrodes on one side of a pair of transparent substrates sandwiching a liquid crystal layer. and a liquid crystal display panel in which a plurality of signal electrodes are orthogonally arranged in a matrix, and a scan pulse for odd scan electrodes and a scan pulse for even scan electrodes corresponding to the odd scan electrodes and the even scan electrodes of the scan electrodes. a scanning electrode driving circuit that outputs a signal using an interlace method; a signal electrode driving circuit that applies a driving voltage to the signal electrode; and a driving timing of the scanning electrode driving circuit and the signal electrode driving circuit based on horizontal and vertical synchronization signals. In the liquid crystal display device, a scan electrode external terminal connects each of the odd-numbered scan electrodes and each of the even-numbered scan electrodes in common to the scan electrode drive circuit; The apparatus further includes a connection state switching circuit that switches the connection between each of the odd scan electrodes and the scan electrode external terminal and the connection between each of the even scan electrodes and the scan electrode external terminal based on drive timing.

(Function) In the liquid crystal display device of the present invention, since a scanning pulse is applied to the even-numbered scanning electrodes and the odd-numbered scanning electrodes from a common external terminal,
The number of external terminals can be reduced, reducing the number of parts.

(Implementation flIJ) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention.

In the figure, 11 indicates a liquid crystal display panel. This liquid crystal display panel 11 has a pair of transparent substrates (not shown), and a liquid crystal is sealed between these transparent substrates. One of these transparent substrates is provided with a grounded transparent common electrode. On the other substrate, scanning electrodes Y1, Y2,... Y2 are arranged in parallel.
Signal electrodes X1, X2,...Xm orthogonal to n
are arranged in parallel, and a switching element S2 of a thin film transistor is provided at each intersection of the scanning electrode and the signal electrode.

A total of 40 thin film transistors Q1, Q2, two each for each of the scanning electrodes Y1, Y2, Y2n.
, -Q2n, TI, T2, -=-= T2n are provided. The drains of T1, T2, . . . T2n are connected to the scanning electrodes Y1, Y2, . . . Y2n, respectively, and the sources are grounded. Ql, Q2,...
The source of Q2n is connected to scanning electrodes Y1, Y2,...
Connect to Y2n respectively, Ql and Q2, Q3 and Q4, ・
... Connect the drains of Q2n-1 and Q2n, respectively, and then connect the external terminals Z1, Z2, ...
... Connect to Zn. Ql, Q3,... Q
2n-1 Kate and T2, T4,...T2n
The gates of both are commonly connected and connected to external terminal A1. Q2
, Q4, ...... Gate of Q2n and TI, T3,
. . . The gates of T2n-1 are commonly connected and connected to the external terminal A2.

In addition, 12 is a scanning electrode drive circuit, 14 is a signal electrode drive circuit, 15 is a video signal,] 6 is a horizontal/vertical synchronization signal, and 17
18 is an inverter, D2 is a liquid crystal display pixel, L2 is a liquid crystal in the liquid crystal display pixel D2 portion, and C2 is a voltage applied between the electrodes of the liquid crystal display pixel D2. It is a capacitor that holds the voltage.

FIG. 2 is a diagram showing the timing of pulses applied to each terminal of the liquid crystal display panel and the scanning electrode.

The operation of the liquid crystal display device having the above configuration will be explained using FIGS. 1 and 2.

First, the video signal 15 is sent to the signal electrode drive circuit 14 horizontally and
Vertical synchronization signal 16 is input to timing control circuit 17 .

The scan electrode drive circuit Co-2 drives the scan electrode external terminal Z as shown in FIG.
Scanning pulses VZI, VZ2, . . . VZn with one field period are applied to 1, Z2, . . . Zn. Furthermore, the timing control circuit 17 applies the voltage VAI to the A1 terminal so that it is at a high level during odd field periods and at a low level during even field periods.

Since the inverter 18 is connected between the terminal A1 and the terminal A2, the voltage VA2, which is an inversion of VAl and the high level and low level, is applied to the terminal A2.

In an odd field, a high level voltage is applied to the terminal A1, and a low level voltage is applied to the terminal A2, so that the switching elements Q1, Q3,...Q2n-
1 and T2, T4, ...... T2n become conductive, and switch elements Q2, Q4, ...... Q2
n and T1, T3, . . . T2n-1 are in a non-conductive state.

Therefore, the scanning pulses applied to Zl, Z2, ... Zn Z1, VZ2, ...... V Z n
c. Odd scanning electrodes Y1, T3,...Y2n
-1, even scan electrodes Y2, T4,...
- Y2n is grounded and serves as a reference potential.

In an even field, a low level voltage is applied to the terminal A1, and a high level voltage is applied to the terminal A2, so that the switching elements Q2, Q4,...Q2n
And T1, T3, . . . T2n-11 becomes conductive, and switch elements Q1, Q3, . . .
Q2n-1 and T2, T4, . . . T2n become non-conductive.

Therefore, the scanning pulses VZ1, vZ2, ...... VZn applied to Zl, Z2, ...... Zn are:
Applied to even scan electrodes Y2, T4, ...... Y2n, and applied to odd scan electrodes Y1, T3, ...... Y2n
-1 is grounded and serves as a reference potential.

That is, a scanning pulse input to the liquid crystal display panel 11 at one field period is applied to the odd scanning electrodes during odd field periods and to the even scanning electrodes during even field periods. As a result, scanning electrodes Y1, T2, . . . Y2n are provided with scanning pulses VY1, ■Y2, . . . VY corresponding to each odd and even field period in one frame period.
n is applied to perform interlaced scanning.

On the other hand, the signal electrode drive circuit 14 applies a signal electrode drive voltage to the signal electrode terminals X1, X2, . . . A driving voltage is applied to the corresponding liquid crystal display pixel D2 on the scanning electrode to which the scanning pulse is applied, and an image is displayed on the liquid crystal display panel 11.

In addition, the switch elements Q1, Q2,...Q2n
For T1, T2, . . . T2n, n-channel enhancement type thin film transistors having the same structure and manufacturing process as the switch elements provided in each liquid crystal display pixel are used.

In this way, the conventional liquid crystal display device required 20 external terminals for 20 scanning lines, but in the liquid crystal display device of this embodiment, the scanning electrode drive circuit requires n external terminals. Since it is commonly used for odd-numbered scan electrodes and even-numbered scan electrodes, the number of parts is reduced.

[Effects of the Invention] As explained above, according to the liquid crystal display device of the present invention,
Since a scan pulse is applied to the odd-numbered scan electrodes and the even-numbered scan electrodes from a common scan electrode drive circuit, the number of parts is reduced, and the cost and size can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an active matrix type liquid crystal display device according to an embodiment of the present invention, and FIG. 2 shows the voltage applied to each external terminal and each scanning electrode of the active matrix type liquid crystal display device shown in FIG. Diagram showing voltage timing, 3rd
The figure shows the configuration of a conventional active matrix liquid crystal display device. DESCRIPTION OF SYMBOLS 11...Liquid crystal display panel, 12...Scanning electrode drive circuit, 14...Signal electrode drive circuit, 17...Timing control circuit, 18...Inverter, Xl, X2,...
・Xm...Signal electrode, Yl, T2,... Y2n・
・・Scanning electrode, Ql, Q2, -Q2n, TI, T2,・
...T2n...Thin film transistor.

Claims (1)

[Claims] A liquid crystal display in which scanning electrodes and signal electrodes, each consisting of a plurality of odd-numbered electrodes and a plurality of even-numbered electrodes, are arranged orthogonally in a matrix on one side of a pair of transparent substrates sandwiching a liquid crystal layer. a panel; a scan electrode drive circuit that outputs scan pulses for odd scan electrodes and scan pulses for even scan electrodes in accordance with the odd scan electrodes and the even scan electrodes of the scan electrodes in an interlaced manner; A liquid crystal display device comprising: a signal electrode drive circuit that applies a drive voltage; and a control circuit that controls drive timing of the scan electrode drive circuit and the signal electrode drive circuit based on horizontal and vertical synchronization signals, a scan electrode external terminal that pairs a scan electrode and each of the even-numbered scan electrodes and commonly connects them to the scan electrode drive circuit; and a scan electrode external terminal that connects each of the odd-numbered scan electrodes and the scan electrode external terminal based on the drive timing of the control circuit. 1. A liquid crystal display device comprising: a connection state switching circuit for switching the connection between the even-numbered scan electrodes and the scan electrode external terminal;