JPH05241124A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To enhance the reliability of a device by suppressing power consumption and reducing the number of wiring between printed boards. CONSTITUTION:This device is a liquid crystal display device arranging a pixel electrode on one side printed board in a matrix shape and providing a transistor 104 on at every pixel and active-matrix-driving and a counter electrode being a common electrode normally is divided parallel to a scanning line at every row and a shift register 103 driving the counter electrode, a T flip-flop 110 and a voltage changeover switch 111 are formed on the printed board of the counter electrode side and the potential of the counter electrode is inverse-driven at every one frame or at every one row.

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 for displaying images and the like.

[0002]

2. Description of the Related Art Liquid crystal display devices that display by utilizing the orientation of liquid crystals have been used from the initial display of simple numbers and symbols such as clocks and calculators to the recent high-definition image display such as televisions. In particular, in the case of a liquid crystal display device, a small device such as a portable TV is expected because the screen can be made thin.

The first requirement for a mobile device such as a portable television is that it be lightweight. In electric equipment, it is not uncommon for a power source such as a battery to drive the electric equipment to occupy most of the weight in particular, and it is a very important factor that the power consumption is as small as possible and a low-capacity power source can be driven for a long time.

However, in the case of the conventional liquid crystal display device using the TN liquid crystal, in order to prevent the phenomenon called sticking peculiar to the liquid crystal panel and improve the reliability, the potential applied to the pixel is inverted at regular intervals. Was normal. Normally, the TN liquid crystal is driven by 0 to 5V, but in order to perform this inversion, ± 5V with respect to the common electrode of constant potential,
That is, it is necessary to input a signal having an amplitude of 10 V, and the power consumption is doubled. As a means for solving such a problem, for example, as disclosed in JP-A-58-49989 and JP-A-60-163091, the potential of the counter electrode is inverted between positive and negative. There is a driving means whose amplitude is reduced to half.

[0005]

According to the above-mentioned prior art, although it is possible to surely reduce the power consumption, any means for controlling the potential of the counter electrode is provided on the substrate on the pixel electrode side. Further, since it is common to the control means of the gate of the transistor of the driving circuit, a large number of wirings are required between the upper and lower substrates, the manufacturing process is complicated, the yield is low, and the reliability of the device is low.

[0006]

The present invention is a liquid crystal display device which solves the above problems. That is, the present invention is a liquid crystal display device in which a liquid crystal is sealed between two substrates via a spacer, and a voltage is applied between electrodes provided on each substrate to control the orientation of the liquid crystal to perform display. One of the substrates is an active matrix substrate in which pixel electrodes are arranged in a matrix and transistors are arranged for each pixel electrode, and the other electrode is divided into parallel electrodes and the potential control of the opposite electrodes A liquid crystal display device is provided with means.

According to the present invention, the potential control means for the counter electrode, specifically, the shift register, the T flip-flop, and the voltage changeover switch in the embodiments described later are provided on the counter electrode side substrate so that two substrates are provided. The number of wires between can be minimized. Further, by dividing the counter electrode in parallel with the scanning line and inverting each potential row by row or frame by frame, it is possible to drive with power consumption of an effective value as in the conventional case.

The potential control means according to the present invention and the transistor installed in each pixel are not particularly limited,
A bulk transistor formed on a single-crystal Si substrate that has been used in the conventional reflection type or a transmission-type polycrystalline or amorphous Si transistor is preferably used, and preferably a single-crystal Si thin film is formed on a transparent substrate. A TFT (thin film transistor) is used. Further, as the other capacitance driving circuits and the forming methods thereof, conventional ones can be preferably used.

FIG. 6 shows a schematic cross-sectional view of a main part of the liquid crystal display device of the present invention. This figure is an example of a transmissive liquid crystal display device,
The switching element uses a single crystal Si transistor, and the drive circuit uses a transistor made of polycrystalline Si. In the figure, 601 is an insulating layer, 602 is a transparent electrode (pixel capacitance), 603 is a pixel electrode, 604 and 604 'are alignment control films for aligning liquid crystals, 605 is a liquid crystal layer, 606 is a counter electrode, and 607 is polycrystalline. Si transistor, 609 is an active matrix substrate, 610 is a counter electrode substrate, 6
Reference numeral 11 is a single crystal Si transistor.

[0010]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

Embodiment 1 FIG. 1 shows an equivalent circuit of the first embodiment of the present invention. 1 in the figure
Reference numeral 01 is a scan line driving shift register, 102 is a display line driving shift register, 103 is a counter electrode driving shift register, shift registers 101 and 102 are on a pixel electrode side substrate, and shift register 103 is a counter electrode. It is formed on the side substrate. Reference numeral 104 is a transistor for switching pixel electrodes, 105 is a pixel capacitance, 106 is a liquid crystal capacitance, 107 is a sampling transistor, and 108 is a sampling transistor.
Is a sampling capacitor, 109 is a reset transistor,
110 is a T flip-flop, 111 is a voltage changeover switch, and 112 is a transfer transistor.

The operation of this embodiment will be described with reference to the timing chart shown in FIG.

Φ _HCK is a clock signal for determining sampling of Video signals of pixels arranged in the horizontal direction (one scanning line). The shift register 102 operates according to φ _HCK , and φ _HL1 , φ _HL2 , and φ _HL3 are sequentially output.
The sampling transistor 107 corresponding to the period when this pulse is “H” is turned on, and the Video signal is accumulated in the sampling capacitor 108. The above operation is performed during the 1H period, and signals for one scanning line are accumulated in all sampling capacitors.

Next, a pulse is applied to φ _VCK to operate the shift register 101. As a result, the gate voltage V _n connected to the n-th scanning line becomes “H”, and the corresponding transistor 104 is turned on. The shift register 101 is configured so that φ _VCK is in the “H” period during the ON period.

While V _n is "H", the following two operations are performed.

Φ _{RES is set} to "H", the reset transistor 109 is turned on, and the potentials of the pixel capacitor 105 and the liquid crystal capacitor are set to V _RES . Next, after φ _{RES is set} to “L” and the reset transistor 109 is turned off, φ _{T is set} to “H”, and the Video signal for one scanning line accumulated in the sampling capacitor 108 is supplied to the n-th scanning line. Pixel capacitance 105 and liquid crystal capacitance 106 through the corresponding transistor 104.
Write in.

The above is the operation during the 1H period,
By repeating this for the number of scanning lines (rows), the entire panel can be driven.

Further, the potentials V _{C1 to} V _C3 of the counter electrodes are shown in FIG.
And Video signal input and the pixel electrode potential V ₁₁ of the first row and first column.

V _{C1 to} V _C3 are shifted by 1H and inverted every frame. The Video signal is also inverted every frame in response to the switching of the counter electrode potential. Therefore, the pixel electrode potential V ₁₁ in the first row and the first column corresponds to V _C1 . The inversion of the counter electrode potential is performed during the reset period of V ₁₁ .

Embodiment 2 FIG. 4 shows an equivalent circuit of the second embodiment of the present invention, and FIG. 5 shows its timing chart. In Example 1,
Although the potential of the counter electrode is inverted every frame, in the present embodiment, the connection of the voltage changeover switch 111 is alternated every other row so that the counter electrode potentials of the nth row and the (N + 1) th row have opposite phases. In this way, driving is performed while inverting the potential for each row.

Example 3 FIG. 7 shows an example in which a metal electrode also serving as a light-shielding layer is provided in a part of the counter electrode of the liquid crystal display device of the present invention to correspond to color display. FIG. 7A is a plan view of the counter electrode,
(B) is a sectional view.

In the figure, reference numerals 701 and 701 'denote counter electrodes, which are normally made of transparent ITO. Reference numerals 702 and 702 'denote metal electrodes, which also serve as a light shielding layer, and W or Al is used as a material. 703 and 703 'are color filters, 704
Is an insulating film, 705 is a glass substrate, and 706 is an orientation control film. In this embodiment, a low-resistance metal electrode is provided to serve as an auxiliary electrode of the counter electrode, and a light-shielding layer is used to blacken the background of the color image to tighten the image.

Embodiment 4 FIG. 8 shows another embodiment similar to Embodiment 3 in which a metal electrode is provided in a part of the counter electrode to serve as an auxiliary electrode and a light shielding layer. In this embodiment, since the space between the opposing electrodes is completely shielded from light, a higher light shielding effect than that in the third embodiment can be obtained.

In the figure, reference numerals 801 and 801 'denote counter electrodes, and 802.
˜802 ″ is a metal electrode, 803 and 803 ′ are color filters, 804 is an insulating film, 805 is a glass substrate, and 806
Is an orientation control film.

[0025]

As described above, in the liquid crystal display device of the present invention, the counter electrode is divided in parallel with the scanning line and the control means provided on the counter electrode side performs the inversion drive to suppress the power consumption low. As it is, the number of wiring between the substrates is reduced to improve the reliability of the device. Further, by providing the divided counter electrodes with metal electrodes, it is possible to improve the color image and reduce the resistance.

[Brief description of drawings]

FIG. 1 is an equivalent circuit of a first embodiment of the present invention.

FIG. 2 is a timing chart of the first embodiment of the present invention.

FIG. 3 is a timing chart of the first embodiment of the present invention.

FIG. 4 is an equivalent circuit of the second embodiment of the present invention.

FIG. 5 is a timing chart of the second embodiment of the present invention.

FIG. 6 is a cross-sectional view of main parts of an example of the liquid crystal display device of the present invention.

7A and 7B are a plan view and a sectional view of a main part of a third embodiment of the present invention.

FIG. 8 is a plan view and a sectional view of a main part of a fourth embodiment of the present invention.

[Explanation of symbols]

 101-103 shift register 104 transistor 105 pixel capacity 106 liquid crystal capacity 107 sampling transistor 108 sampling capacity 109 reset transistor 110 T flip-flop 111 voltage changeover switch 112 transfer transistor 601 insulating layer 602 transparent electrode 603 pixel electrode 604, 604 'orientation control film 605 Liquid crystal layer 606 Counter electrode 607 Transistor 608 Transparent substrate 609 Active matrix substrate 610 Counter electrode substrate 611 Transistor 701, 701 'Transparent electrode 702, 702' Metal electrode 703 Color filter 704 Insulating film 705 Glass substrate 706 Alignment control film 801, 801 ' Transparent electrode 802-802 "Metal electrode 803 Color filter 804 Insulating film 805 Glass substrate 806 Alignment control film

Claims (1)

[Claims] 1. A liquid crystal display device in which liquid crystal is sealed between two substrates via a spacer, and a voltage is applied between electrodes provided on each of the substrates to control the alignment of the liquid crystal for display. One of the substrates is an active matrix substrate in which pixel electrodes are arranged in a matrix and transistors are arranged for each pixel electrode, and the other electrode is divided into parallel electrodes and the potential control of the opposite electrodes A liquid crystal display device characterized in that means are formed.