JPH07159802A - Reflection type liquid crystal display device - Google Patents

Abstract

PURPOSE:To reduce the size, weight and thickness of a display device by adopting the constitution to commonly use a reflection plate, liquid crystal pixel driving circuit board and a substrate for mounting a driving circuit for one of two sheets of the substrates constituting a liquid crystal element. CONSTITUTION:The substrate 1 is a transparent substrate, such as, for example, glass, and transparent electrodes are formed on the inner side of the substrate 1. Upper and lower contact holes 3, 6, signal electrodes 4, scanning electrodes 5 and pixel parts 7 are constituted on the inner side of the substrate 2. Further, a driving IC 9 and a peripheral circuit 8 are mounted at the outer side of the substrate 2. The signal electrodes 4, the scanning electrodes 5 and the pixel parts 7 serve to drive liquid crystals 10, for which the prescribed circuity is adopted. The pixel parts of this circuit are composed of TFTs and the liquid crystals are driven by these TFTs. The peripheral circuit 8 generates the voltages, timing signals, etc., for operating the driving IC 9. Insulating materials consisting of ceramics etc., are commonly usable as a reflection plate and are, therefore, convenient if such insulating materials are used as the more specific example of the substrate 2.

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,
In particular, the present invention relates to a reflective liquid crystal display device suitable for realizing a lightweight, thin, and inexpensive display device.

[0002]

2. Description of the Related Art As a conventional reflection type liquid crystal display device, there is known a liquid crystal display device in which a MOS transistor is formed on a silicon substrate and a liquid crystal is laminated on the MOS transistor to drive the liquid crystal. In this technique, the circuits necessary for driving the liquid crystal can be collectively formed on the substrate, so that the display device can be made very compact.

[0003]

However, in addition to the display size of this display device being at most 2 to 3 inches,
It is difficult to apply to a low-cost display device because of its high manufacturing cost. For this reason, a large-sized and high-definition reflective display device can be manufactured by a simple method, and the structure of the device is low.

[0004]

One substrate constituting a liquid crystal element is a substrate that also serves as a pixel pattern forming substrate including a reflector and a TFT and a drive IC mounting substrate, and the output of the drive IC is set to a plurality of upper and lower sides. It is transmitted to the scan electrodes and the signal electrodes through the contact holes.

[0005]

A thin and large-sized display device can be constructed by providing one substrate of the liquid crystal element with three functions of a substrate for forming a reflection plate, a TFT and the like and a substrate for mounting a driving IC.

Further, by supplying the driving voltage to the scanning electrodes and the signal electrodes at a plurality of locations, it is possible to relieve the wiring defects and reduce the waveform distortion.

[0007]

FIG. 1 shows an example of the structure of a reflective liquid crystal display device according to the present invention. The display device 11 includes a substrate 1 and a substrate 2. A power supply circuit 12 and an external system circuit 13 such as a CPU are connected to the display device.

The substrate 1 is, for example, a transparent substrate such as glass, and a transparent electrode is formed inside the substrate. The transparent electrode is not always necessary. Further, in some cases, a color filter is formed. Liquid crystal 10
Is a liquid crystal such as TN (twisted nematic) liquid crystal, PDLC (polymer dispersed liquid crystal) and GH (guest host) liquid crystal, and the liquid crystal used is not particularly limited.

Upper and lower contact holes 3, 6, signal electrodes 4, scanning electrodes 5 and pixel portions 7 are formed inside the substrate 2, and a driving IC 9 and a peripheral circuit 8 are attached outside the substrate. There is. The signal electrode 4, the scanning electrode 5, and the pixel portion 7 drive the liquid crystal 10, and have the circuit configuration shown in FIG. In this circuit, the pixel section 7 is T
It is composed of FT14, and the liquid crystal is driven by this TFT. T
The FT is composed of a-Si and p-Si transistors, but MOS type transistors may be used. These transistors are collectively formed on the substrate 2 by the exposure and etching techniques. However, a chip piece for each pixel or for each plurality of pixels is prepared in advance and then this substrate 2 is used.
You may attach it to. Note that the pixel portion may have only the signal electrode and the scan electrode other than the configuration shown in FIG.

The driving IC 9 generates a signal voltage for driving the signal electrode 4 and a scanning voltage for driving the scanning electrode 5. The signal voltage is transmitted to the signal electrode 4 through the upper and lower contact holes 6, and one scanning voltage is applied to the upper and lower contact holes 3.
Is transmitted to the scan electrode 5 via. The upper and lower contact holes 3 and 6 may be formed by mechanical or etching, and the forming method is not particularly limited. The peripheral circuit 8 generates a voltage and a timing signal for operating the drive IC 9. As a concrete example of the substrate 2, it is convenient to use an insulating substrate made of ceramics or the like because it can be used also as a reflector. Also, a transparent substrate may be used without any particular limitation. FIG. 3 is a specific example of the wiring formed on the back surface of the substrate 2. Scan drive IC17
Output voltage is transmitted to the scan electrodes through the upper and lower contact hole groups 14 and 15. When the scanning voltage is applied from the left and right sides of the scanning electrodes as in this embodiment, the following effects are obtained.

In the scanning electrode 5 shown in FIG. 2, a relatively high resistance wiring material such as chromium, tantalum, molybdenum, ITO, etc. can be stably formed easily. Further, as the definition becomes higher, the wiring resistance becomes higher.
Since it is connected to the gate electrode of, the capacitance capacitance is large and the waveform distortion of the scanning voltage is large. When the waveform distortion becomes large, the switching operation of the TFT cannot be sufficiently performed, which causes deterioration of display image quality. However, when the scanning voltage is applied to the scanning electrodes from both ends, the above-mentioned problem is solved. In order to obtain the same effect as that of the present invention in the conventional technique, it is necessary to install the driving ICs on both sides of the scanning electrode, so that the number of ICs to be used increases and there is a problem in the simplification of the device and the cost.

The signal voltage generated by the signal driving IC 18 is transmitted to the signal electrode through the upper and lower contact hole groups 16. Although not shown, the signal voltage may also be added to the signal electrode by providing a group of contact holes on the upper and lower sides similarly to the scanning voltage described above.

FIG. 4 shows the arrangement of the scan driving IC 17 on the substrate 2.
It is an example installed from the center of. With such an arrangement, the substrate can be made smaller, which is advantageous for miniaturization. In this case, an insulator is formed between the output line of the scan driving IC 17 and the wiring between the upper and lower contact hole groups 14 and 15 so as not to short-circuit. Further, the connection method between the output terminal of the drive IC and the upper and lower contact hole groups is wire bonding connection, solder connection, etc., but the method is not particularly limited.

FIG. 5 shows another embodiment of the connection pattern between the scan driving IC and the scan electrodes. The output of the drive IC is transmitted to the scan electrodes through the upper and lower contact hole groups 19 to 23. The number of contact holes per scanning electrode line shown in the figure is 5, but it is not particularly limited and may be arbitrary. The larger the number of upper and lower contact holes in one line, the greater the wiring resistance of the scanning electrodes, which is convenient in manufacturing, and a display device with higher definition can be configured. Further, even if the wiring width is partially narrowed and the resistance is increased, by increasing the number of upper and lower contact holes, the drive waveform distortion due to the higher resistance can be reduced, and therefore the manufacturing margin of the process such as etching can be increased. As a result, it becomes possible to form the scanning electrodes and the like by the printing technique which is said to have a problem in the finished dimension accuracy, and there is an effect that the process steps are shortened. Depending on the case, almost all of the pattern wiring including the portion where the drive IC is mounted may be formed by the printing technique. Further, even if a defect such as a disconnection of the scan electrode wiring occurs, the defect can be remedied by providing a plurality of upper and lower contact holes. As a result, the yield can be improved, which is advantageous in reducing the cost of the device.

The maximum number of upper and lower contact holes is the number in the lateral direction of the TFT shown in FIG. As a result, since the scanning wiring can be omitted, defects such as disconnection of the wiring can be eliminated. Signal drive IC (not shown)
The connection between the scan electrode and the signal electrode may be the same as the connection method between the scan driving IC and the scan electrode described above.

[0016]

According to the present invention, of the two substrates constituting the liquid crystal element, one of the substrates serves as the reflector, the liquid crystal pixel drive circuit substrate, and the drive circuit mounting substrate. It is possible to reduce the size, weight and thickness. This makes it possible to achieve a display device that is optimal for the handy type.

Further, since it is possible to provide a plurality of points for transmitting the driving voltage to the wiring necessary for driving the display, the driving IC
It is possible to reduce the distortion of the drive waveform without increasing the number of, and to realize high-definition and high-quality display.

Furthermore, since a high resistance material can be used for the wiring material of the display driving section, the manufacturing is easy, and the process margin in the manufacturing can be made gentle. It is suitable for price.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an entire liquid crystal display device according to the present invention.

FIG. 2 is a circuit diagram used for a front portion.

FIG. 3 is an explanatory diagram of an example of a connection pattern between a drive IC and upper and lower contact holes.

FIG. 4 is an explanatory diagram of an example of a connection pattern between a drive IC and upper and lower contact holes.

FIG. 5 is an explanatory diagram of an example of a connection pattern between a drive IC and upper and lower contact holes.

[Explanation of symbols]

3, 6 ... Upper and lower contact holes, 4 ... Signal electrode, 5 ... Scan electrode, 7 ... Pixel portion, 8 ... Peripheral circuit, 9 ... Driving IC, 1
0 ... Liquid crystal.

Claims (2)

[Claims] 1. A reflection type liquid crystal display device for displaying an image on a panel in which a liquid crystal is interposed between one substrate and the other substrate, wherein the inside of the other substrate has a reflection function and a pattern portion is formed inside. A reflective liquid crystal display device having a driving IC mounted on the outside. 2. The reflective liquid crystal display device according to claim 1, wherein one output of the drive IC is transmitted to an electrode of the pixel portion through a plurality of upper and lower contact holes.