JP2007034327A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an auxiliary capacitor laid in a pixel, without decreasing the aperture ratio, in an active matrix display device. <P>SOLUTION: The apparatus includes: a gate wiring line connected to a gate electrode of a thin film transistor; a first insulating film on a gate electrode, the gate wiring line, a gate insulating film, and an active layer; a source wiring line arranged on the first insulating film and connected to a source area; a second insulating film formed on the source wiring line; a light shielding electrode formed of chromium on the second insulating film; a lead electrode formed on the second insulating film, connected directly to a drain area, and made of the same material with the light shielding electrode; a third insulating film on the light shielding electrode and lead electrode; and a pixel electrode formed on the third insulating film and connected directly to the lead electrode. The light shielding electrode has a portion which overlaps a part or the entire periphery of the pixel electrode and is arranged to cover the source wiring line, and the light shielding electrode and lead electrode are formed on the same plane. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The invention disclosed in this specification relates to a structure of a pixel region of an active matrix liquid crystal display device. More specifically, the present invention relates to a configuration of an auxiliary capacitor and a black matrix (BM) connected in parallel with the pixel electrode.

  The present invention also relates to the configuration of a pixel region of a flat panel display that requires a black matrix.

  An active matrix type liquid crystal display device is known. In this method, at least one thin film transistor is connected to each of a large number of pixel electrodes provided in a matrix, and charges entering and exiting the pixel electrode are controlled by the thin film transistors.

  The pixel electrode forms a capacitor (capacitor) between the opposing electrodes across the liquid crystal. The thin film transistor functions as a switching element that controls the input and output of electric charges to and from this capacitor.

  However, in actual operation, the capacitance formed by the pixel electrode portion is too small and it is necessary to provide an auxiliary capacitance.

  However, when the electrode for forming the capacitor is made of a conductive material such as a metal material, there is a portion that shields light in the pixel, so that the aperture ratio is lowered.

  On the other hand, a member that blocks light such as a black matrix is required around the pixel electrode.

  In general, in a region where source wiring (wiring for supplying current to the source region of a thin film transistor) and gate wiring (wiring for supplying a signal potential of the gate electrode of the thin film transistor) arranged in a grid pattern are formed. , The upper part will swell.

  As a result, the rubbing treatment for the alignment film in this portion does not work well, and the orientation of the liquid crystal molecules in that portion is disturbed. As a result, a phenomenon in which light leaks or a light does not pass through a predetermined amount appears in the peripheral portion of the pixel. In addition, it is impossible to perform a predetermined electro-optical operation on the liquid crystal in this portion.

  When the above phenomenon occurs, the display around the pixel becomes blurry, and the overall sharpness of the image is lost.

  As a configuration for solving this problem, there is a configuration in which a light shielding film is disposed so as to cover the edge portion of the pixel electrode. This light shielding film is called a black matrix (BM).

  As a configuration for arranging such a black matrix, a configuration described in US Pat. No. 5,339,181 is known. In the technique described in this publication, as shown in FIG. 2C, a black matrix extending from the gate line is arranged so as to overlap the edge of the pixel electrode. Further, it is devised that an auxiliary capacitance is formed at the overlapping portion of the black matrix and the pixel electrode.

  However, the technique described in the above publication has the following two problems. First, since the black matrix extends from the gate line, there is a problem that complete light shielding cannot be performed.

  This is because the source line and the black matrix cannot be overlapped due to the crosstalk. Therefore, it must be permitted that light leaks at that portion.

  As a second problem, since the black matrix is arranged in the same layer as the gate line, it is natural that the gate line itself cannot be shielded from light. Further, the source line cannot be shielded from the above-described crosstalk.

  In recent years, with the development of digital equipment, the influence of electromagnetic waves from low frequencies to microwaves has become a problem. That is, in the environment where the liquid crystal electro-optical device is used, there is a concern about the influence of the electromagnetic waves.

  Therefore, it is necessary that the liquid crystal potential optical device is not easily affected by such electromagnetic waves.

  In consideration of this, a configuration in which a source line or a gate line to which an image signal is transmitted, such as the configuration described in the above-mentioned US Pat. No. 5,339,181, is not preferable. This is because there is a concern that the source line and the gate line function as an antenna.

  An object of the invention disclosed in this specification is to provide a configuration for obtaining effective light shielding by a black matrix in a configuration of a pixel of an active matrix liquid crystal display device.

  It is another object of the present invention to provide a configuration that protects the entire apparatus from the influence of external electromagnetic waves.

  It is another object of the present invention to form an auxiliary capacity of a required capacity without causing a decrease in aperture ratio.

As one of the inventions disclosed in this specification, as shown in FIG. 1 and FIG.
A source wiring 113 and a gate wiring 110 arranged in a grid pattern;
At least one pixel electrode 118 is disposed in a region surrounded by the source wiring or the gate wiring,
An electrode 116 that covers the source wiring 113 and the gate wiring 110 and shields visible light is disposed,
The periphery of the pixel electrode 118 overlaps the electrode 118 that blocks the visible light,
The overlapping region (indicated by 119 and 120) functions as an auxiliary capacity.

  In the above structure, all the portions other than the pixel electrode 118 and the drain region of the thin film transistor 103 can be shielded from incident light. In particular, the source line and the gate line can be completely shielded from the outside. By doing so, it is possible to prevent electromagnetic waves from entering the source line and the gate line from the outside and causing malfunctions and malfunctions of the apparatus.

In addition, an auxiliary capacitor can be formed without causing a decrease in the aperture ratio. Further, it is possible to completely shield light other than the pixel electrode.

  In the above configuration, the pixel electrode is formed of a transparent conductive film such as ITO. In the basic configuration, one pixel electrode is provided for each pixel, but there is a configuration in which the pixel electrode is divided into a plurality of pixels in one pixel.

  The black matrix 116 arranged so as to overlap with the peripheral edge portion of the pixel electrode is made of titanium or chromium. This black matrix not only functions as a light-shielding film, but also functions as one electrode constituting an auxiliary capacitor.

  The metal electrode 116 is preferably overlapped as much as possible in the entire periphery of the pixel electrode. That is, it is preferable that the overlap between the metal electrode 116 and the pixel electrode 118 is realized in most of the peripheral portion of the pixel electrode 118.

The configuration of another invention is, for example, as illustrated in FIG. 1 and FIG.
A source wiring 113 and a gate wiring 110 arranged in a grid pattern;
In the region surrounded by the source wiring 113 or the gate wiring 110, at least one pixel electrode 118 is disposed.
An electrode 116 is disposed on the periphery of the pixel electrode to shield light,
The pixel electrode 118 and the electrode 116 that shields light constitute a capacitor through an insulating film 117,
The electrode 116 for shielding light, the source line 113 and the gate line 110 are arranged in different layers.

  As another example of the configuration of the invention, as illustrated in FIG. 1 and FIG. 2, for example, a pixel electrode 118, a light shielding electrode 116, a source wiring 113, and a gate wiring 110 are sequentially arranged from the incident light side (upper side in FIG. 1). A capacitor (indicated by 119 or 120) is formed between the pixel electrode and the light shielding electrode.

  In the above configuration, the pixel electrode is disposed closest to the incident light side, and then the light shielding electrode 116 (black matrix) is disposed, whereby the source line and gate line disposed in the lower layer, and the thin film transistor (other than the drain region) are arranged. ) Can be completely shielded from light.

  This configuration is very useful not only for shielding light but also for eliminating the influence of external electromagnetic waves.

  Further, the capacitance indicated by 119 or 120 can be formed without causing a decrease in the aperture ratio.

  By partially overlapping the black matrix covering the periphery of the pixel electrode and the pixel electrode with an insulating film interposed therebetween, that portion can be configured as an auxiliary capacitor. By doing so, it is possible to prevent the aperture ratio of the pixel from being lowered. Further, since the insulating film can be thinned, the capacitance value can be increased.

  That is, it is possible to provide a configuration for obtaining effective light shielding by the black matrix.

  Moreover, the structure which protects the whole apparatus from the influence of the electromagnetic waves from the outside can be provided.

The invention disclosed in this specification is used not only in an active matrix type liquid crystal electro-optical device but also in a flat panel display that requires a black matrix covering a pixel electrode and its periphery and an auxiliary capacitor connected to a thin film transistor. be able to.

  1 and 2 show a structure of an active matrix liquid crystal display device using the invention disclosed in this specification.

  A cross section taken along line A-A 'in FIG. 2 is shown in FIG. 1 and 2 show a state of one pixel constituting a pixel region (the pixel region is composed of a large number of pixels) of an active matrix type liquid crystal display device.

  Further, FIG. 1 and FIG. 2 show only the structure on the substrate side where the thin film transistor is arranged. In practice, there are also opposing substrates. Then, the liquid crystal is held with a gap of several μm between the substrate and the substrate shown in FIG.

  1 and 2, the thin film transistor is formed in a portion indicated by 103. 1 and 2, reference numeral 101 denotes a glass substrate. In addition to the glass substrate, a quartz substrate is used. Reference numeral 102 denotes a silicon oxide film constituting the base film. 104, 107, 105, 108, 106 is an active layer of the thin film transistor. This active layer is formed of a crystalline silicon film obtained by crystallizing an amorphous silicon film by heating or laser light irradiation.

  In this active layer, 104 is a source region, 107 and 108 are offset gate regions, 105 is a channel formation region, and 106 is a drain region.

  Reference numeral 109 denotes a silicon oxide film functioning as a gate insulating film. Reference numeral 110 denotes a gate electrode extending from a gate wiring mainly composed of aluminum. In the figure, 110 is shown for both the gate electrode and the gate wiring.

  Reference numeral 111 denotes an anodized film formed by performing anodization using aluminum as an anode.

  Reference numeral 112 denotes a first interlayer insulating film made of a silicon oxide film. Reference numeral 113 denotes an extraction electrode extending from the source line 104 from the source region 104. In the figure, both the source electrode and the source line are indicated by 113.

  Reference numeral 115 denotes an extraction electrode from the drain region 106 and is connected to an ITO electrode 118 serving as a pixel electrode. Reference numeral 114 denotes a second interlayer insulating film, and 117 denotes a third interlayer insulating film.

  Reference numeral 116 denotes a titanium electrode also serving as a black matrix. In addition to titanium, chromium or the like is used. The titanium electrode 116 is disposed so as to overlap the peripheral portion of the pixel electrode 118 so as to function as a black matrix.

  A region where the titanium electrode 116 and the pixel electrode 118 overlap is an auxiliary capacitance. That is, in the portions indicated by 119 and 120, a capacitor is formed between the pixel electrode 118 and the titanium electrode 116 via the third interlayer insulating film 117. This capacity can be large because the insulating film 117 can be thin.

The titanium electrode 116 also shields the gate line 110 and the source line 113, and can prevent the generation and accumulation of charges due to the irradiation of strong light. The titanium electrode also functions as a shield against external electromagnetic waves. In other words, the gate line 110 and the source line 113 also have a function of preventing unnecessary signal intrusion due to the antenna.

  Further, the titanium electrode 116 is disposed so as to cover the thin film transistor 103 as well. This is to prevent the operation of the thin film transistor from being affected by light.

  Here, a configuration in which the insulating film 117 is a single layer is shown. However, the insulating film 117 may have a multilayer structure.

A state of a pixel region of an active matrix liquid crystal display device is shown. A state in which a pixel region of an active matrix liquid crystal display device is viewed from above is shown.

Explanation of symbols

101 glass substrate 102 base film (silicon oxide film)
103 Thin film transistor 104 Source region 105 Channel formation region 106 Drain region 107, 108 Offset gate region 109 Gate insulating film 110 Gate electrode (gate line)
111 Anodized film 112 First interlayer insulating film 113 Source electrode (source line)
114 Second interlayer insulating film 115 Drain electrode 116 Titanium electrode constituting black matrix (electrode constituting capacitance)
117 Third interlayer insulating film 118 Pixel electrode (ITO electrode)
119, 120 Part where auxiliary capacitance is formed

Claims (16)

A display device in which a thin film transistor having a gate electrode, a gate insulating film, and an active layer is arranged in a pixel,
A gate wiring electrically connected to the gate electrode of the thin film transistor;
The gate electrode, the gate wiring, the gate insulating film and the first insulating film on the active layer;
A source wiring disposed on the first insulating film in a lattice with the gate wiring and electrically connected to a source region provided in the active layer;
A second insulating film formed on the source wiring;
The same material as the light-shielding electrode made of chromium formed on the second insulating film and the light-shielding electrode formed on the second insulating film and directly connected to the drain region provided in the active layer An extraction electrode comprising:
A third insulating film on the light shielding electrode and the extraction electrode;
A pixel electrode formed on the third insulating film and directly connected to the extraction electrode;
The light-shielding electrode has a portion that overlaps a part or all of the periphery of the pixel electrode, and is disposed so as to cover the source wiring,
The display device, wherein the light shielding electrode and the extraction electrode are formed on the same plane. A display device in which a thin film transistor having a gate electrode, a gate insulating film, and an active layer is arranged in a pixel,
A gate wiring electrically connected to the gate electrode of the thin film transistor;
The gate electrode, the gate wiring, the gate insulating film and the first insulating film on the active layer;
A source wiring disposed on the first insulating film in a lattice with the gate wiring and electrically connected to a source region provided in the active layer;
A second insulating film formed on the source wiring;
The same material as the light-shielding electrode made of chromium formed on the second insulating film and the light-shielding electrode formed on the second insulating film and directly connected to the drain region provided in the active layer An extraction electrode comprising:
A third insulating film on the light shielding electrode and the extraction electrode;
A plurality of divided pixel electrodes formed on the third insulating film and directly connected to the lead electrodes;
The light-shielding electrode has a portion that overlaps a part or all of the periphery of the pixel electrode, and is disposed so as to cover the source wiring,
The display device, wherein the light shielding electrode and the extraction electrode are formed on the same plane. A display device in which a thin film transistor having a gate electrode, a gate insulating film, and an active layer is arranged in a pixel,
A gate wiring electrically connected to the gate electrode of the thin film transistor;
A base film formed under the active layer;
The gate electrode, the gate wiring, the gate insulating film and the first insulating film on the active layer;
A source wiring disposed on the first insulating film in a lattice with the gate wiring and electrically connected to a source region provided in the active layer;
A second insulating film formed on the source wiring;
The same material as the light-shielding electrode made of chromium formed on the second insulating film and the light-shielding electrode formed on the second insulating film and directly connected to the drain region provided in the active layer An extraction electrode comprising:
A third insulating film on the light shielding electrode and the extraction electrode;
A pixel electrode formed on the third insulating film and directly connected to the extraction electrode;
The light-shielding electrode has a portion that overlaps a part or all of the periphery of the pixel electrode, and is disposed so as to cover the source wiring,
The display device, wherein the light shielding electrode and the extraction electrode are formed on the same plane. A display device in which a thin film transistor having a gate electrode, a gate insulating film, and an active layer is arranged in a pixel,
A gate wiring electrically connected to the gate electrode of the thin film transistor;
A base film formed under the active layer;
The gate electrode, the gate wiring, the gate insulating film and the first insulating film on the active layer;
A source wiring disposed on the first insulating film in a lattice with the gate wiring and electrically connected to a source region provided in the active layer;
A second insulating film formed on the source wiring;
The same material as the light-shielding electrode made of chromium formed on the second insulating film and the light-shielding electrode formed on the second insulating film and directly connected to the drain region provided in the active layer An extraction electrode comprising:
A third insulating film on the light shielding electrode and the extraction electrode;
A plurality of divided pixel electrodes formed on the third insulating film and directly connected to the lead electrodes;
The light-shielding electrode has a portion that overlaps a part or all of the periphery of the pixel electrode, and is disposed so as to cover the source wiring,
The display device, wherein the light shielding electrode and the extraction electrode are formed on the same plane. A display device in which a thin film transistor having a gate electrode, a gate insulating film, and an active layer is arranged in a pixel,
A gate wiring electrically connected to the gate electrode of the thin film transistor;
The gate electrode, the gate wiring, the gate insulating film and the silicon oxide film on the active layer;
A source wiring disposed on the silicon oxide film in a lattice with the gate wiring and electrically connected to a source region provided in the active layer;
A first insulating film formed on the source wiring;
The same material as the light-shielding electrode made of chromium formed on the first insulating film and the light-shielding electrode formed on the first insulating film and directly connected to the drain region provided in the active layer An extraction electrode comprising:
A second insulating film on the light shielding electrode and the extraction electrode;
A plurality of divided pixel electrodes formed on the second insulating film and directly connected to the lead electrodes;
The light-shielding electrode has a portion that overlaps a part or all of the periphery of the pixel electrode, and is disposed so as to cover the source wiring,
The display device, wherein the light shielding electrode and the extraction electrode are formed on the same plane. A display device in which a thin film transistor having a gate electrode, a gate insulating film, and an active layer is arranged in a pixel,
A gate wiring electrically connected to the gate electrode of the thin film transistor;
A base film formed under the active layer;
The gate electrode, the gate wiring, the gate insulating film and the silicon oxide film on the active layer;
A source wiring disposed on the silicon oxide film in a lattice with the gate wiring and electrically connected to a source region provided in the active layer;
A first insulating film formed on the source wiring;
The same material as the light-shielding electrode made of chromium formed on the first insulating film and the light-shielding electrode formed on the first insulating film and directly connected to the drain region provided in the active layer An extraction electrode comprising:
A second insulating film on the light shielding electrode and the extraction electrode;
A pixel electrode formed on the second insulating film and directly connected to the extraction electrode;
The light-shielding electrode has a portion that overlaps a part or all of the periphery of the pixel electrode, and is disposed so as to cover the source wiring,
The display device, wherein the light shielding electrode and the extraction electrode are formed on the same plane. A display device in which a thin film transistor having a gate electrode, a gate insulating film, and an active layer is arranged in a pixel,
A gate wiring electrically connected to the gate electrode of the thin film transistor;
A base film formed under the active layer;
The gate electrode, the gate wiring, the gate insulating film and the silicon oxide film on the active layer;
A source wiring disposed on the silicon oxide film in a lattice with the gate wiring and electrically connected to a source region provided in the active layer;
A first insulating film formed on the source wiring;
The same material as the light-shielding electrode made of chromium formed on the first insulating film and the light-shielding electrode formed on the first insulating film and directly connected to the drain region provided in the active layer An extraction electrode comprising:
A second insulating film on the light shielding electrode and the extraction electrode;
A plurality of divided pixel electrodes formed on the second insulating film and directly connected to the lead electrodes;
The light-shielding electrode has a portion that overlaps a part or all of the periphery of the pixel electrode, and is disposed so as to cover the source wiring,
The display device, wherein the light shielding electrode and the extraction electrode are formed on the same plane. A display device in which a thin film transistor having a gate electrode, a gate insulating film, and an active layer is arranged in a pixel,
A gate wiring electrically connected to the gate electrode of the thin film transistor;
A base film made of a silicon oxide film formed under the active layer;
The gate electrode, the gate wiring, the gate insulating film and the first insulating film on the active layer;
A source wiring disposed on the first insulating film in a lattice with the gate wiring and electrically connected to a source region provided in the active layer;
A second insulating film formed on the source wiring;
The same material as the light-shielding electrode made of chromium formed on the second insulating film and the light-shielding electrode formed on the second insulating film and directly connected to the drain region provided in the active layer An extraction electrode comprising:
A third insulating film on the light shielding electrode and the extraction electrode;
A pixel electrode formed on the third insulating film and directly connected to the extraction electrode;
The light-shielding electrode has a portion that overlaps a part or all of the periphery of the pixel electrode, and is disposed so as to cover the source wiring,
The display device, wherein the light shielding electrode and the extraction electrode are formed on the same plane. A display device in which a thin film transistor having a gate electrode, a gate insulating film, and an active layer is arranged in a pixel,
A gate wiring electrically connected to the gate electrode of the thin film transistor;
A base film made of a silicon oxide film formed under the active layer;
The gate electrode, the gate wiring, the gate insulating film and the first insulating film on the active layer;
A source wiring disposed on the first insulating film in a lattice with the gate wiring and electrically connected to a source region provided in the active layer;
A second insulating film formed on the source wiring;
The same material as the light-shielding electrode made of chromium formed on the second insulating film and the light-shielding electrode formed on the second insulating film and directly connected to the drain region provided in the active layer An extraction electrode comprising:
A third insulating film on the light shielding electrode and the extraction electrode;
A plurality of divided pixel electrodes formed on the third insulating film and directly connected to the lead electrodes;
The light-shielding electrode has a portion that overlaps a part or all of the periphery of the pixel electrode, and is disposed so as to cover the source wiring,
The display device, wherein the light shielding electrode and the extraction electrode are formed on the same plane. A display device in which a thin film transistor having a gate electrode, a gate insulating film, and an active layer is arranged in a pixel,
A gate wiring electrically connected to the gate electrode of the thin film transistor;
A base film made of a silicon oxide film formed under the active layer;
The gate electrode, the gate wiring, the gate insulating film and the silicon oxide film on the active layer;
A source wiring disposed on the silicon oxide film in a lattice with the gate wiring and electrically connected to a source region provided in the active layer;
A first insulating film formed on the source wiring;
The same material as the light-shielding electrode made of chromium formed on the first insulating film and the light-shielding electrode formed on the first insulating film and directly connected to the drain region provided in the active layer An extraction electrode comprising:
A second insulating film on the light shielding electrode and the extraction electrode;
A pixel electrode formed on the second insulating film and directly connected to the extraction electrode;
The light-shielding electrode has a portion that overlaps a part or all of the periphery of the pixel electrode, and is disposed so as to cover the source wiring,
The display device, wherein the light shielding electrode and the extraction electrode are formed on the same plane. A display device in which a thin film transistor having a gate electrode, a gate insulating film, and an active layer is arranged in a pixel,
A gate wiring electrically connected to the gate electrode of the thin film transistor;
A base film made of a silicon oxide film formed under the active layer;
The gate electrode, the gate wiring, the gate insulating film and the silicon oxide film on the active layer;
A source wiring disposed on the silicon oxide film in a lattice with the gate wiring and electrically connected to a source region provided in the active layer;
A first insulating film formed on the source wiring;
The same material as the light-shielding electrode made of chromium formed on the first insulating film and the light-shielding electrode formed on the first insulating film and directly connected to the drain region provided in the active layer An extraction electrode comprising:
A second insulating film on the light shielding electrode and the extraction electrode;
A plurality of divided pixel electrodes formed on the second insulating film and directly connected to the lead electrodes;
The light-shielding electrode has a portion that overlaps a part or all of the periphery of the pixel electrode, and is disposed so as to cover the source wiring,
The display device, wherein the light shielding electrode and the extraction electrode are formed on the same plane.   12. The display device according to claim 1, wherein the source wiring, the gate electrode, and the gate wiring are shielded from light incident from the pixel electrode side by the light shielding electrode.   13. The display device according to claim 1, wherein the pixel electrode is ITO.   14. The display device according to claim 1, wherein the active layer is a crystalline silicon film.   15. The display device according to claim 1, wherein the gate wiring and the gate electrode are mainly composed of aluminum.   16. The display device according to claim 1, wherein a substrate of the thin film transistor is glass or quartz.

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