JPH07146462A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To reduce mounting terminals, and form a simple wiring structure by connecting two signal input parts of a bidirectional shift register circuit to each other, and arranging switching gates having mutually reversed polarity just before both initial stage shift registers. CONSTITUTION:Both signal input parts of a bidirectional shift register circuit are connected to each other, and a signal inputted from a common signal input terminal 11 is transmitted to both signal input parts 111 and 112. In an optional shift mode, a clock gate which has the same polarity with a clock gate to perform operation to transmit or cut off an input signal according to a signal DIR or the like to determine the shift direction and is arranged just before an initial stage shift register, transmits either one side signal in conformity with the optional shift mode, and cuts off an opposite side signal in unconformity with a shift mode. That is, when the signal DIR is put in high electric potential and the other signal is put in low electric potential, a clock gate just before the input part 111 transmits the input signal, and a gate just before the input part 112 cuts off the input signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device.

[0002]

2. Description of the Related Art The structure of a conventional bidirectional shift register circuit for driving an image display portion of a liquid crystal display device is represented by a logic circuit shown in FIG. The shift direction is determined by two signals DIR and DIRbar. That is, when the signal DIR is at a high potential and the signal DIRbar is at a low potential, the signals input from one signal input terminal 411 are sequentially output from the signal output terminal 421, and vice versa, as shown in the timing chart of FIG. When the signal DIR has a low potential and the signal DIRbar has a high potential, the other signal input terminal 51 as shown in the timing chart of FIG.
The signals input from 2 are sequentially output from the signal output terminal 526.

In the bidirectional shift register circuit which operates according to the above-mentioned mechanism, it is necessary to input a signal only to one of the signal input sections corresponding to the shift mode. Therefore, in the conventional technique, two signal input terminals 511 are provided.
And 512 were independent and existed separately. Therefore, as shown in the equivalent circuit diagram of FIG. 6, two mounting terminals for the input signal are required, and the wiring structure becomes more complicated, and the driver area may be further expanded or densified. was there.

[0004]

In the conventional bidirectional shift register circuit, since the signal input section is provided in two independent positions, two mounting terminals for the input signal are required, and in addition, the driver is provided. Manufacturing a liquid crystal display device with a built-in driver, such as increasing the area or increasing the density and increasing the complexity of the wiring structure. There were challenges in aiming to improve costs.

Therefore, according to the present invention, since the same signal is input to both signal input portions, the terminals are made common to reduce the number of mounting terminals and have a simple wiring structure. It is an object to provide a liquid crystal display device having a register circuit.

[0006]

According to the present invention, a plurality of pixel electrodes arranged in a matrix on one of a pair of substrates in which an electro-optical material is enclosed, a switching transistor connected to the pixel electrodes, and the switching transistor. The image display unit has a plurality of data lines for supplying an image display signal to the transistor and a plurality of gate lines for supplying a gate signal to the switching transistor, and further drives the image display unit. In a liquid crystal display device in which a bidirectional shift register circuit capable of reversing the scanning direction is constituted by thin film transistors and built in a substrate, two signal input parts of the bidirectional shift register circuit are connected to each other, and both first stage shift registers are connected. It is characterized in that it has switching gates of opposite polarities immediately before.

[0007]

As shown in the logic circuit diagram of FIG. 1A, both signal input parts of the bidirectional shift register circuit are connected,
The signal input from the common signal input terminal 11 is transmitted to both signal input units 111 and 112. Here, the clocked gate provided immediately before the first-stage shift register has the same polarity as the clocked gate that transmits or cuts off the input signal according to the signals DIR and DIRbar for determining the shift direction in an arbitrary shift mode. However, it transmits only the signal on one side corresponding to an arbitrary shift mode and cuts off the signal on the other side not conforming to the shift mode. That is, the signal DIR in FIG.
Is a high potential and the signal DIRbar is a low potential, 11
The clocked gate immediately before 1 transmits the input signal, and at the same time, the clocked gate immediately before 112 blocks the input signal. The timing chart in this case is as shown in FIG. On the other hand, when the signal DIR is at a low potential and DIRbar is at a high potential, the clocked gate immediately before 111 blocks the input signal and at the same time the clocked gate immediately before 112 transmits the input signal. The timing chart in this case is as shown in FIG.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a bidirectional shift register circuit having a basic structure as shown in the logic circuit diagram of FIG. 1A is used as a vertical driver for driving gate lines. Signals DIR and DIRb for determining shift direction
As the potential of ar, signals of opposite polarities are applied from dedicated input terminals. When the signal DIR has a high potential and the signal DIRbar has a low potential, the clocked gate 101 series operates as a normal inverter and the clocked gate 102 series does not transmit a signal. Therefore, the signal from the signal input terminal 11 is not transmitted to 112 and
After passing only 1, the signals are sequentially output from the signal output terminal 121 as shown in the timing chart of FIG. If this shift mode is configured as a shift from the top to the bottom of the vertical shift register, the gate lines can be driven from the top to the bottom, and a standard image can be obtained. On the other hand, in the same configuration, the signal D
When IR is at a low potential and the signal DIRbar is at a high potential, the clocked gate 101 series does not transmit a signal, and the clocked gate 102 series operates as a normal inverter. Therefore, the signal from the signal input terminal 11 is not transmitted to 111, passes through only 112, and is sequentially output from the signal output terminal 126 as shown in the timing chart of FIG. In this shift mode, it is possible to drive the gate lines from the bottom to the top as a shift from the bottom to the top in the vertical shift register, so that a vertically inverted image is obtained with respect to the standard image. be able to. In this way, by switching the potentials of the signals DIR and DIRbar that determine the shift direction, it becomes possible to freely input the input signal from one signal input terminal from either one of the two signal input sections. . That is, in the liquid crystal display device as shown in the equivalent circuit diagram of FIG. 4, the mounting terminals of the bidirectional shift register circuit for performing the upside down display can be reduced and the wiring structure can be simplified.

When the two signal input sections of the bidirectional shift register circuit are connected as in the present invention, as described above, the input signal is applied to only one of the signal input sections corresponding to an arbitrary shift mode. It is necessary to have a structure in which the input signal is cut off at the signal input section on the opposite side that is transmitted in accordance with the shift mode, but in order to determine the shift direction in any shift mode as described above. Signal D
Transmission as an element capable of performing similar switching operation instead of the clocked gate provided immediately before the first-stage shift register, which has the same polarity as the clocked gate that transmits or cuts off the input signal according to IR and DIRbar A gate can also be used. A logic circuit diagram in this case is shown in FIG. The timing charts of the two shift modes in this circuit are the same as those shown in FIGS. 3A and 3B, and it can be expected that the circuit operates similarly to the circuit shown in FIG. By using this circuit, it is possible to reduce the number of mounting terminals and simplify the wiring structure.

Up to now, the description has been made of connection of two signal input portions and transmission and cutoff of an input signal at that time when the bidirectional shift register circuit is constructed by using a clocked gate. Concerning the circuit structure of the bidirectional shift register itself, a configuration method using elements other than the clocked gate can be considered. The present invention can be applied to such a circuit as well, and by connecting the signal input sections at two places, the mounting terminals can be reduced and the wiring structure can be simplified. Here, an example of a bidirectional shift register circuit using a transmission gate is shown in the logic circuit diagram of FIG. In this circuit, an element for transmitting or blocking an input signal according to signals DIR and DIRbar for determining a shift direction is composed of a transmission gate, which corresponds to an arbitrary shift mode. A clocked gate or a transmission gate is used as a switching element for transmitting the input signal only to one side signal input section and blocking the input signal at the opposite side signal input section that does not match the shift mode. It is provided immediately before and has the same polarity as a transmission gate that transmits or cuts off an input signal according to signals DIR and DIRbar for determining a shift direction in an arbitrary shift mode. FIG. 2A is a logic circuit diagram when a clocked gate is used as a switching element, and FIG. 2B is a logic circuit diagram when a transmission gate is used.
The timing charts of both circuits are the same as those shown in FIGS. 3A and 3B for the two shift modes.

The bidirectional shift register circuit having the basic structure shown in the examples of the logic circuit diagrams of FIGS. 1 and 2 can be applied to a horizontal driver for driving data lines. Conceivable. From this, the bidirectional shift register circuit for left-right inverted display also
As in the case of the vertical driver, it is possible to form a circuit having a small number of mounting terminals and a simple wiring structure.

[0012]

According to the present invention, it is possible to reduce the mounting terminals and simplify the wiring structure for the bidirectional shift register circuit for performing the up-down or left-right inversion display of the liquid crystal display device. The upside-down or left-right reversal display of an image using the bidirectional shift register circuit can be performed when the liquid crystal display is used as a light valve for a projector, regardless of the installed state such as stationary or ceiling-mounted, and front projection. , A signal for operating a normal unidirectional shift register circuit, which is indispensable as a function for obtaining a normal image regardless of the front and back of the projection surface such as rear projection. In addition to this, a signal for converting the shift mode is required. This may increase the number of mounting terminals and complicate the wiring structure, which may cause a serious problem in design. By solving these problems, it has expanded the possibility of reducing the manufacturing cost of the liquid crystal display device equipped with the inversion display function by the bidirectional shift register circuit.

[Brief description of drawings]

FIG. 1 is a logic circuit diagram of a bidirectional shift register including clocked gates according to the present invention.

FIG. 2 is a logic circuit diagram of a bidirectional shift register including a transmission gate of the present invention.

FIG. 3 is a timing chart of the bidirectional shift register of the present invention.

FIG. 4 is an equivalent circuit diagram of the liquid crystal display device of the present invention.

FIG. 5 is a logic circuit diagram of a conventional bidirectional shift register including clocked gates.

FIG. 6 is an equivalent circuit diagram of a conventional liquid crystal display device.

[Explanation of symbols]

101 ... A clocked gate that determines the shift direction. 102 ... A clocked gate having a polarity opposite to that of 101. 11 ... Signal input terminal. 121-126 ... Signal output terminals. 131 ... One end pulse monitor terminal. 132 ... The other end pulse monitor terminal. 201 ... A transmission gate that determines the shift direction. 202 ... A transmission gate whose polarity is opposite to that of 201. 21 ... Signal input terminal. 221-226 ... Signal output terminals. 231 ... One end pulse monitor terminal. 232 ... The other end pulse monitor terminal. 41 ... Vertical shift register. 42 ... Horizontal shift register. 43 ... Gate line. 44 ... Data line. 45 ... Video line. 46 ... Analog switch. 47 ... Pixel transistor. 48 ... Pixel holding capacity. 49 ... Mounting terminal. 501: a clocked gate that determines the shift direction. 502 ... Clocked gate with opposite polarity to 401. 511 ... One signal input terminal. 512 ... The other signal input terminal. 521-426 ... Signal output terminal. 531 ... One end pulse monitor terminal. 532 ... The other end pulse monitor terminal.

Claims (1)

[Claims] 1. A plurality of pixel electrodes arranged in a matrix on one of a pair of substrates in which an electro-optical material is enclosed, a switching transistor connected to the pixel electrode, and an image display signal is supplied to the switching transistor. Has an image display portion in which a plurality of data lines for supplying the gate signal and a plurality of gate lines for supplying a gate signal to the switching transistor are formed, and the scanning direction can be inverted when the image display portion is driven. In a liquid crystal display device in which a bidirectional shift register circuit is configured by thin film transistors and is built in a substrate, two signal input portions of the bidirectional shift register circuit are connected, and switching gates of opposite polarities are provided immediately before both first-stage shift registers. A liquid crystal display device comprising: