JPS63225282A - Active matrix array type 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] [Summary] The present invention connects a control electrode of a switching element corresponding to a pixel to a corresponding scan canvas line, and connects one of two controlled electrodes to the next scan canvas line. In an active matrix array connected to form a connection group related to a plurality of lines in the form of a ladder, a photovoltaic element is provided between one controlled electrode of the switching element and the next scan canvas line; The control electrode potential is biased in the opposite direction to the potential of the controlled electrode connected to the next scan canvas line by the output voltage of the electromotive force element.

In the active matrix array that constitutes the connection group related to the above-mentioned multi-line staircase, the potential of the controlled electrode connected to the subsequent scan canvas line was increased by the output voltage of the photovoltaic element receiving the backlight. This makes the potential of the control electrode negative with respect to the potential of the controlled electrode, thereby enabling complete off-operation.

[Industrial application field]

The present invention relates to an active matrix display device, and more particularly, the present invention relates to an active matrix display device, in which a control electrode of a thin film transistor is connected to a corresponding scan canvas line, and one of the controlled electrodes is connected to a next scan canvas line, so that a plurality of lines are connected in a ladder-like manner. This invention relates to improvements to active matrix arrays constructed of.

[Conventional technology]

Active matrix display devices, along with simple matrix display devices, are used as terminals for information devices, and liquid crystals are used as the display medium.

Comparing the two, the active matrix type can drive a large number of pixels independently, so even if the number of lines increases with the increase in display capacity, the driving duty ratio is lower than that of the simple matrix type. There is an advantage that problems such as a decrease in contrast and a decrease in viewing angle due to the decrease in contrast do not occur.

However, since a switching element is provided for each pixel, the cost increases and the structure becomes complicated, which poses a problem in manufacturing yield, and these points limit the size of the panel.

In order to solve this problem, the inventors of the present invention proposed a switching element formed on a first insulating substrate 2, for example, a glass substrate, as shown in FIG. 3 in Japanese Patent Application No. 60-274011. thin film transistor (TP)
T) Connect the control electrode 6 of 2 to the scan line (for example, 4-1) corresponding to the pixel, and connect one of the two controlled electrodes 8 and 9 (for example, the source electrode S) to the scan line corresponding to the pixel. is connected to the next scan canvas line (e.g. 4-2), the other controlled electrode (e.g. drain electrode D) is connected to one display electrode of the liquid crystal display pixel 3, and the electrode is placed on the second insulating substrate. An active matrix type display device having a structure in which a data bus line 5 is provided has been proposed.

With this structure, the ground pass line can be omitted, increasing the drive area ratio, and there are no intersections of pass lines on the same insulating substrate, improving manufacturing yield. do.

In order to operate such a TPT as an active matrix element to perform a desired display, it is necessary to perform a complete off operation when the TPT is turned off so as to maintain sufficient charge accumulated in the liquid crystal.

TPTs constituting the active matrix usually use an intrinsic semiconductor and a gate insulating film without charge traps, so as shown in FIG. The dark value voltage in the drain current (■, ) characteristic with respect to ) is approximately Ov. Therefore, in order to turn off the TPT, the gate voltage of the TPT must be lower than Ov.

[Problem that the invention seeks to solve]

Therefore, in the equivalent circuit shown in FIG. 3 above, in order to completely turn off these TPT2s, TPT2
It is necessary to make the gate voltage V6 of
, the potential of the next scan canvas line 4-2 is vl [■], and the potential of the next scan canvas line 4-3 is
The potential of 2×v.

(V).

However, the number of scan lines is usually several hundred, so even if ■ is 0.5V, hundreds of ■ must be applied to the final line, and the driving power supply, RC, circuit configuration, etc. All of them had their drawbacks, and the problem was that they could not be adopted as they were.

The present invention provides T in an active matrix having the above configuration.
An object of the present invention is to provide an active matrix display device that can easily raise the potential of a controlled electrode connected to the next scan canvas line to be higher than the potential of a control electrode in order to turn off a PT. shall be.

[Means for solving problems]

As shown in FIG. 1, the present invention relates to one controlled electrode 8 of the switching element 2 and the next scan canvas line 4-2, 4-3. A photovoltaic element 10 was inserted between the two electrodes so that the output voltage of the photovoltaic element 10 would bias the potential of the control electrode 6 in the opposite direction with respect to the controlled electrode 8.

[For production]

When an electron accumulation type TPT is used as the switching element 2, the output voltage of the photovoltaic element 10 causes the potential of the controlled electrode 8 to change to the scan canvas line 4-2.4-3. Insert it in a direction that will push it higher than the potential of...

With this configuration, scan canvas lines 4-1, 4-2, 4-3 . ... are commonly set as OV, the photovoltaic element 10 generates an output voltage when irradiated with a backlight, etc., and this output voltage changes the potential of the control electrode 6 to the controlled electrode 4-2.4- 3. Since the TPT2 is negatively biased with respect to..., the TPT2 is completely turned off.

〔Example〕

An embodiment of the present invention is shown in FIGS. 1 and 2(a) below.

(Explained by bl.

FIG. 1 is an explanatory diagram of the configuration of one embodiment of the present invention, FIG. 2(a) is a plan view showing the structure of the above embodiment, and FIG. 2(b) is (al
It is a sectional view taken along the line B-B of FIG.

In the figure, 1 is a display electrode made of 1,000 thick ITO, 2 is TPT, 3 is a liquid crystal display pixel, and 4 is an ITO with a thickness of about 1,000 thick.
Scan canvas line consisting of TO (gate pass line)
, S and D are source (S) electrodes and drain (D) electrodes made of titanium (Ti) film having a thickness of about 1000 μm, respectively, G is the gate electrode of TPT 2, and scan canvas line 4 corresponding to each pixel. -1, 4-2, 4-3
, connect to... Also, 5 is a data bus line,
10 is each source electrode S and the next scan canvas line 4-2.4-3. to which each source electrode S is connected. The photovoltaic device 10 has a structure in which an a-3i film 12 with a thickness of approximately 5000 mm is sandwiched between the scan canvas line 4-2.4- 3. ...
The irradiation light from the backlight irradiation means 11 is transmitted through the ITO film which is the constituent material of the backlight irradiation means 11. Furthermore, 13 is the above a
- an Al film connecting between the 3i film 12 and the source electrode S;
14 is an insulating substrate.

As seen in FIGS. 1 and 2 (al, (b)), this embodiment has a plurality of scan canvas lines 4-1.4 to 2.4-3 arranged in parallel. Between them, TPTs 2 corresponding to pixels are arranged in a matrix, and the gate electrodes G are connected to scan canvas lines 4-1, 4-2 corresponding to the pixels.
．． 4-3. ..., and the source electrode S is connected to the next scan canvas line 4-2゜4- through the photovoltaic element 10.
3. It has a configuration connected to...

Further, the active matrix type display device of this embodiment is a bank light type display device, and includes bank light irradiation means 11 for illuminating the liquid crystal display pixels 3 from the back side.

When the photovoltaic element 10 is irradiated with a backlight,
Generates a voltage of approximately 0.7V. Therefore, each scan canvas line 4-1.4-2.4-3. ...
When the applied voltage is OV, the potential of the source electrode S of the TPT is changed to the scan canvas line 4-1.4-2.4-3 due to the electromotive force of the photovoltaic element 10. ...that is, gate electrode G
It becomes 0.7V higher than the potential of . In other words, the gate electrode G
is biased at -0.7■ with respect to the source electrode S. As a result, the TFT 2 is turned off, as is clear from FIG. 4.

As described above, in this embodiment, each scan canvas line 4-1.4-2.4-3. ... simply change the potential to O
By setting the voltage to V, the gate electrode G is negatively biased with respect to the potential of the source electrode S, so that the TPT can be completely turned off.

Therefore, for off operation, scan canvas line 4-1
．． 4-2.4-3. The conventional problem of increasing the voltage of ... toward the rear is completely solved in this embodiment.

Note that the above embodiment describes an example using an electron accumulation type TPT, but when using a hole accumulation type TPT, the photovoltaic elements 10 are connected so that the direction of the photovoltaic force is reversed. do it.

〔Effect of the invention〕

According to the present invention, a transistor can be completely turned off with a simple structure and without using high voltage, and a high-quality image can be obtained.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the configuration of one embodiment of the present invention, Figure 2 is a tag,
(b) is a plan view showing the structure of the above embodiment and B-B
3 is an equivalent circuit diagram of a conventional active matrix display panel, and FIG. 4 is a diagram showing current characteristics with respect to gate voltage of TPT. In the figure, 1 is a display electrode, 2 is a TPT, 3 is a liquid crystal display pixel, 4-1, 4-2, 4-3, ... are scan canvas lines, 5 is a data bus line, 6 is a control electrode, 8
．． 9 is an electrode to be controlled, 10 is a photovoltaic element, 11 is a bank light irradiation means, and S, D, and G each represent the present invention - circle general! J=Ji to Tsueakim Figure 1 Shizumi, Zun<By-Tajun-2 Shishii ffJ-ri Seij Sagimi Tl Akira 21 Figure 2

Claims (1)

[Claims] A switching element (2) corresponding to a pixel is provided between a plurality of scan canvas lines (4-1, 4-2, 4-3, . . . ) arranged in parallel on an insulating substrate. are arranged in a matrix,
The control electrode (6) of each switching element is connected to the corresponding scan canvas line (4-1, 4-2, 4-3,...), and one of the two controlled electrodes (8) is connected to the scan canvas line (4-2, 4-3,...)
In an active matrix array in which a plurality of lines are connected to each other to form a connection group related to each other in the form of a ladder, the one controlled electrode (8) and the next scan canvas line (4-2, 4-3,...)
A photovoltaic element (10) that generates a voltage when irradiated with light is placed between the control electrode (6) and the controlled electrode (8) depending on the output voltage of the photovoltaic element. 1. An active matrix array type display device, characterized in that the active matrix array type display device is inserted so as to be biased in a direction opposite to that of the active matrix array type display device.