JPS6068325A - Thin film transistor substrate - Google Patents

Abstract

PURPOSE:To enable stable display with high contrast by providing light shielding members consisting of light-absorptive org. films or pigment-dispersion layers on a laminated structural body of a thin film transistor substrate. CONSTITUTION:Light shielding members 6, 6' are provided on the laminated structural body of a thin film transistor substrate consisting of gate electrodes 1'', 1''', insulating films 5, 5', semiconductors 2'', 2''', source wires 3, 3', drain electrodes 4'', 4''', etc. A black or dark colored material having light absorptivity and chemical stability is preferable as the members 6, 6' for which light- absorptive org. films or pigment-dispersion layers are preferred. A material which does not cause unnecessay chemical reaction between the layer 11, the semiconductors 2'', 2''', etc. and the members 6, 6' in the case of bringing the members 6, 6' into direct contact with said liquid crystal layer, etc. The members 6, 6' in common use as a mask to conceal the nonimage display parts, i.e., semiconductor parts, source or gate wires, etc. which dot contribute to display of the image are also usable.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in thin film transistor substrates used in liquid crystal display devices, particularly in liquid crystal display cells in which a driving semiconductor array is integrally provided on a substrate constituting the display device.

Liquid crystal display devices are: (1) Passive displays with extremely low power consumption.

(21) Must be able to operate at low voltage.

(3) What can be done with panel-type elements?

(4) Large-scale display is also possible.

Because they have characteristics not found in light-emitting (active) displays, much research and development has been carried out in recent years.

Among such liquid crystal display devices, Japanese Patent Application Laid-Open No. 50-17599
A large number of pixels as shown in the publication)
2. Description of the Related Art Display devices driven by multiplexes have been attracting particular attention.

That is, as shown in FIG. 1(a), drive thin film transistors (T F
T ; Th1n Film Transistor)
It has been established. TPT includes gate lines 1m and 13' (made of transparent or metal thin conductive films) formed on a substrate S, and gate electrodes 1. 1′,
III, III, an insulating film laminated on the electrode, and a thin film semiconductor formed on the gate electrode with an insulating film interposed therebetween. 2', f, 2'', a source line (made of a conductive film) 3.3' provided in contact with one end of the semiconductor, and a drain electrode 4.4', 4", 4" provided on the other end of the semiconductor, etc. It consists of

FIG. 1(b) is a plan view viewed from the direction of arrow B in FIG. 1(a), and shows a part of the matrix drive circuit.

Further, FIG. 2 shows an enlarged sectional view of FIG. 1(b) taken along line segment AA'. In FIG. 2, 7 and S are substrates such as glass, 4 and 4 are the aforementioned drain electrodes,
8 is a conductive film of a counter electrode. 4,4 Otsu 8th place is I
A transparent conductive film such as n2O3-5n02 or a metal thin film such as Au, AI, Pd, etc. is used depending on the case. 1", #', and 3.3' are a gate electrode and a source line, respectively, and are AI.

Metals such as Au, Ag, Pt, Pd, Cu, etc. are used.

5. 5' and 9 are insulating films, 2'', with a depth of Cd8°C.
These are semiconductors such as dS e, 10 spacers, and 11 liquid crystal layers. Note that the display device uses dynamic scattering mode (DSM).
・Depending on which display mode such as twisted nematic (TN) is used or whether the device is transmissive or reflective, various liquid crystal molecule orientation states and polarization plates, λ/4 plates, and reflector plates are available. Optical detection means such as the above are appropriately set.

To outline the driving method, for example, gate line 1a.

When an image signal is applied to 1a' and a driving voltage is scanned and applied to source line 3.3' (only while a signal is input to the gate line), a selected one of the intersections of these electrodes is applied. Source (3, 3') - Drain (4, 4"')
When conduction occurs between the drain electrode and the counter electrode (8), an electric field is generated between the drain electrode and the counter electrode (8), and display is performed by changing the arrangement state of liquid crystal molecules in the liquid crystal layer 11. However, since the display device described above is of a passive type, the following problems have occurred. That is, since the display device is a passive type, it is necessary to illuminate the display surface with external light.
``CdS, the material of T.

Since semiconductors such as CdSe have remarkable photoconductivity, their operating characteristics may become unstable.

In addition, in order to improve these points, we have proposed a method using Te, which is a semiconductor whose electrical characteristics are not affected by external light, or a method using Te, which is a semiconductor whose electrical characteristics are not affected by external light, or a method using CaF2 and 8i0 to prevent external light from entering the semiconductor part.
A method has also been proposed in which a multilayer reflective film consisting of 2 layers is laminated on a semiconductor portion.

However, when using Te as a semiconductor, it is unfavorable in terms of versatility and toxicity, and the method of forming an increased reflection film requires a multilayer film with a precise thickness, which requires many steps and is complicated. This may cause inconveniences such as

The present invention has been made in view of the above points, and the main purpose of the present invention is to provide a display cell having stable operating characteristics. Another object of the present invention is to provide a display cell in which good characteristics can be obtained without restricting the freedom in selecting materials in terms of versatility, toxicity, etc. Or again,
Another object of the present invention is to provide a display cell in which the contrast can be easily improved.

The present invention, which achieves these objects, is characterized in that a liquid crystal display cell in which a semiconductor drive circuit is provided on a display substrate is provided with a light shielding member for blocking light incident on the semiconductor portion. do.

By providing a member that shields light incident on the semiconductor portion in this manner, a display cell with stable operating characteristics can be obtained.

FIG. 3 shows the cross-sectional structure of the display cell of the present invention (those with the same numbers as in FIG. 2 indicate the same ones)
. Compared to the cell shown in FIG.
' is provided on the semiconductor portion. Although this configuration shows an example in which the incident direction of external light is above the substrate 11, the installation location of the light-transmitting member can be changed depending on whether the display cell is used as a projection type, transmission type, or reflection type. Can be done. In the present invention, although the objective can be achieved by providing the light-transmitting member on any part of the display cell, such as on the inner wall side of the substrate or on the outer side of the substrate, it is preferable to provide it on the inner wall side of the substrate. Note that the "inner wall side" of the substrate refers to the inner side of the substrates 7 and S in FIG. 2, that is, the side of the liquid crystal layer 11.
It points to the side of the wall closest to.

As the light-transmitting member, a black or dark-colored light-absorbing and chemically stable material is preferable. For example, lotus hei member 6.6
When making direct contact with the liquid crystal layer 11, the semiconductors 2, 2', etc., it is desirable to select a material that will not cause any unnecessary chemical reaction between these and the thin film member. As a light-transmitting member, a light-absorbing organic film or a layer in which an organic pigment is dispersed is provided.

Another advantage of the display cell of the present invention is that the light-transmitting member can also serve as a mask for obscuring image non-display areas; ie, semiconductor areas, sources, gate lines, and other areas that do not contribute to image display.

When such a mask is provided, adjacent display segments (drain electrodes) are visually separated from each other, and the reflectance of the non-display portions of the display device as a whole to external light is reduced, resulting in a relative improvement in contrast. . In particular, when the display device is of a transmissive type or a color display device, the effect of improving contrast is remarkable.

Further, in the present invention, if a light-transmitting member is used for the insulating film 5.5' provided under the semiconductors 2 and 2', the gate electrode 1.1', or the contact portion between the source or gate electrode and the semiconductor, etc. , more favorable results are obtained.

The display cell of the present invention not only provides good contrast for static displays, but also provides stable, high-contrast display for video displays that require high responsiveness, such as TV images. . When high-speed response is required, such as in the case of television image signals, it is desirable to provide a storage capacitor in parallel to each segment and use it as a frame memory. A cross-sectional view of the display cell in this case is shown in FIG. The storage capacitor is constituted by a conductive film 13 extending from the adjacent gate to below the drain electrode with an insulating film 12 in between.

The liquid crystal display cell of the present invention can be made thinner and more compact by providing a polarizing plate, a reflecting plate, a λ/4 plate color filter, etc. as appropriate, so that it can be used in various display modes and can be of a projection type, transmission type, or reflection type. As a display device, it is applied to various panel displays, such as display boards for clocks or calculators, cabin televisions, monitors for video cameras, etc.

[Brief explanation of the drawing]

Fig. 1(a) is a perspective view showing a part of the board having a semi-moving body drive circuit, Fig. 1(b) is a plan view thereof, and Fig. 2 shows the board shown in Figs. 1(a) and (b). FIG. 3 is a cross-sectional view showing a part of the display cell of the present invention, and FIG. 4 is a diagram showing another embodiment of the present invention. In the figure, la, la'--gate lines Th1, 1'
, 1//, lAl1. ,,gate electrode,2.2',2
#, 2″...Semiconductor, 3.3'...Source line, 4.
4', 4", 4"...Drain electrode, 5°5',
9.12. I...Insulating film, 6.6'...Light transparent member, 7. S: Substrate, 8: Conductive film, 10: Spacer, 11: Liquid crystal layer, 13: Conductive film. Applicant Canon Co., Ltd.

Claims (1)

[Claims] Button on substrate In a thin film transistor substrate in which a laminated structure having a gate electrode, an insulating film, a semiconductor film, and a source electrode and a drain electrode in contact with the semiconductor film is arranged in a matrix, a light-absorbing organic film or a light-absorbing organic film is provided on the laminated structure. A thin film transistor substrate characterized in that it is provided with a light-speed shielding member made of a pigment-dispersed layer.