JP2633360B2 - Image display device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a liquid crystal image display device formed using a thin film transistor on an insulating substrate.

2. Description of the Related Art A conventional image display device will be described below. FIG. 3 shows a conventional configuration diagram. There is a driving circuit including a vertical scanning circuit 11 and a horizontal scanning circuit 12. At each output of the horizontal scanning circuit 12, a transfer transistor switch group 13 controlled by an output of the horizontal scanning circuit 12 is formed. The pixel units 14 are arranged in a two-dimensional matrix and are driven by an active matrix system. A horizontal gate line, which is an output of the vertical scanning circuit 11, is formed of polysilicon, and a vertical signal line is formed of aluminum (Al), and is written to a pixel portion in a dot-sequential manner.

However, in such a conventional configuration, when there is a short circuit between the horizontal gate line, which is the output of the vertical scanning circuit 11, and the vertical signal line from the horizontal scanning circuit 12, only the circuit inspection means is required. It is very difficult to find the location, and there is a drawback that an image must be displayed and inspected after the fabrication of the circuit, through the liquid crystal process, and after the display device is completed.

The present invention has been made in view of the above-described drawbacks, and provides an image display device that can determine a short-circuit portion before a liquid crystal process when there is a line short-circuit between a horizontal gate line and a vertical signal.

Means for Solving the Problems In order to solve the above problems, an image display device according to the present invention comprises a multi-control terminal for forming a logical sum circuit at each end of a vertical signal line and a horizontal gate line passing through a pixel portion. A pattern inspection switch is provided, and each signal line is connected to each control terminal of each inspection switch.

Operation According to the above configuration, a multi-control terminal type inspection switch is provided at each of the end of the vertical signal line passing through the pixel portion and the end of the horizontal gate line, and each inspection switch forms a NOR circuit with a resistor. can do. A pulse shorter than the selection period of the output from the horizontal scanning circuit is input to the input terminal of the transfer transistor switch controlled by the output from the horizontal scanning circuit. If there is a short circuit between the vertical signal line and the horizontal gate line, the output of each test switch provided at each end of the signal line and the horizontal gate line will have the same waveform at the place where the short circuit occurs. Becomes

The present invention is based on the above principle, and provides an image display device capable of easily examining whether or not there is a short circuit between a vertical signal line and a horizontal gate line and its position.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a configuration diagram of an image display device according to an embodiment of the present invention. 1 is a vertical scanning circuit, 2 is a horizontal scanning circuit, 3 is a transfer transistor switch (group), 4 is a pixel portion, 5 is a multi-gate transistor as a vertical signal line multi-control terminal switch element, and 6 is a horizontal gate line. A multi-gate transistor as a multi-control terminal switch element, 7 is a horizontal gate line, and 8 is a vertical signal line. Each pixel of the pixel section 4 is of an active matrix type and has a switching thin film transistor. The output section of the horizontal scanning circuit 2 includes a transfer transistor switch (group) 3 controlled by the output of the horizontal scanning circuit 2, and includes a pixel section 4.
Signal transmission is performed by dot-sequential writing using Al wiring.

Next, a method of checking a short circuit between the vertical signal line passing through the pixel unit 4 and the horizontal gate line, that is, a so-called short circuit, in the image display device of the present invention will be described. FIG. 2 (a),
(B) shows the configuration diagram and a voltage waveform diagram at each point.
A, B, and C indicate output waveforms of the horizontal scanning circuit 2, and D indicates a test pulse input to the transfer transistor switch (group) 3. Each vertical signal line 8 is a vertical signal line inspection switch 5.
Are connected to the respective gate electrodes, that is, the control terminals,
The source and drain electrodes are common and are connected in parallel. The vertical signal line inspection switch 5 forms a NOR circuit with the resistor R. Further, F and G are output waveforms of the vertical scanning circuit 1, and each horizontal gate line 7 is connected to each gate electrode of a horizontal gate line inspection switch 6 having the same shape as the vertical signal line inspection switch 5. The horizontal gate line inspection switch 6 and the resistor R form a NOR circuit. The size of the resistor R is set to be larger than the on-resistance and smaller than the off-resistance of each multi-gate transistor used for each of the inspection switches 5 and 6.

Here, for example, it is assumed that the vertical signal line 8 and the horizontal gate line 7 are short-circuited at a fulcrum indicated by an arrow in the drawing. First, the horizontal scanning circuit 2 is driven without driving the vertical scanning circuit 1. Each output waveform of the horizontal scanning circuit 2 is
A, B, and C of FIG. A test pulse is input to the terminal D, and the output of the terminal H is observed. If there is a short circuit at the arrow, the output signal is transmitted to the terminal H, and it can be confirmed that there is a short circuit somewhere on the extension of the transfer transistor switch 3 controlled by the output of the terminal B. Next, the horizontal scanning circuit 2 is stopped, and no pulse is input to the terminal D, and only the vertical scanning circuit 1 is driven. FIG. 2B shows output waveforms of the terminals F and G in FIG. If there is a short circuit at the arrow, an output waveform also appears at the terminal E while the output at the terminal G is present, indicating that there is a short circuit on the extension of the horizontal gate line 7. From the above results, the short-circuited portion can be determined. When there is no short circuit in the pixel section 4, the output of the terminals E and H does not appear at all even if the above inspection is performed.

As described above, the multi-control terminal type inspection switch is provided at the end of each signal line of the pixel display device, and NO is determined by the resistance R.
By forming an R circuit and observing the output waveform at each of the terminals E and H, it is possible to check each signal line one by one or use the vertical signal lines that were unknown until the image was displayed through the liquid crystal process. The short circuit between the horizontal gate lines and the position thereof can be easily known before the liquid crystal process.

In the embodiment, the inspection switches are formed by juxtaposed multi-gate thin film transistors, respectively.
Therefore, this inspection switch can be manufactured at the same time when the horizontal and vertical scanning circuits are formed, so that it is not necessary to add a new process.

In this embodiment, a multi-gate type transistor is used as the inspection switch. However, another multi-control terminal type switch element configuration may be used. The resistor may be a thin film, externally or internally provided, or a load connection resistor having a transistor structure. Further, each of the transfer transistor switch (s) may be an n-channel transistor or a p-channel transistor, or
A CMOS TFT configuration may be used.

As described above, the feature of the present invention resides in that a multi-control terminal type inspection switch is provided at each of the end of the horizontal gate line and the end of the vertical signal line, and a NOR circuit is formed by the switch and the resistance of the load connection. is there. According to such a configuration, by simply checking the output signal of the inspection pulse, the presence / absence of a short circuit between the horizontal gate line and the vertical signal line, which has been difficult in the past, and the location thereof can be easily determined before the liquid crystal process. In addition, such an OR circuit has a great practical effect, such as good signal separation between each signal of a horizontal gate line or a vertical signal line and an output signal.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an image display device according to an embodiment of the present invention, and FIGS. 2 (a) and 2 (b) are a configuration diagram of a test example of a short circuit between lines according to an embodiment of the present invention, a voltage waveform diagram, and FIG. FIG. 1 is a configuration diagram of a conventional image display device. 1 vertical scanning circuit 2 horizontal scanning circuit 3 transfer transistor switch (group) 4 pixel unit 5 5
Vertical signal line multi-control terminal type inspection switch, 6 horizontal gate line multi-control terminal type inspection switch, 7 horizontal gate lines, 8 vertical signal lines.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Koji Senda 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Denshi Kogyo Co., Ltd. (72) Inventor Kazunori Kobayashi 1006 Kadoma, Kazuma, Osaka Prefecture Matsushita Electronics Corporation (56) References JP-A-60-2989 (JP, A) JP-A-63-52121 (JP, A)

Claims (1)

(57) [Claims] An image signal is supplied to a horizontal scanning circuit and a vertical scanning circuit formed by a thin film transistor on an insulating substrate, a pixel portion arranged in a two-dimensional matrix, and pixels in each column formed by a conductive film. A vertical signal line to be supplied and a horizontal gate line, and an output unit of the horizontal scanning circuit includes a transfer switch for transferring a video signal controlled by an output pulse from the horizontal scanning circuit to the vertical signal line, An image display, wherein an end of the vertical signal line and an end of the horizontal gate line are respectively connected to respective control terminals of a multi-control terminal switch element for forming a separate OR circuit. apparatus.