Electro-optical device and electronic apparatus

An electro-optical device includes a short-circuit wire provided in a peripheral area surrounding a pixel area in which pixel electrodes are provided. The short-circuit wire includes a main portion that short-circuits scanning lines with each other and an extending portion that extends from the main portion in such a manner as to intersect data lines. A wire supplied with a predetermined potential in the peripheral area is electrically connected to the extending portion.

BACKGROUND

1. Technical Field

The present invention relates to electro-optical devices, such as liquid crystal display devices, and electronic apparatuses, such as liquid crystal projectors, including the electro-optical devices.

2. Related Art

There is an exemplary electro-optical device disclosed in JP-A-2001-339065. This electro-optical device is manufactured in such a manner that, after a short-circuit wire is formed, cutting of the short-circuit wire and formation of data lines are performed simultaneously. The short-circuit wire is provided for preventing damage to thin-film transistors (TFTs) brought by static electricity generated during the manufacturing process.

There is another exemplary electro-optical device disclosed in JP-A-2005-309003. In this electro-optical device, an electrostatic protection circuit that suppresses the occurrence of overvoltage of an image-signal wire is provided on a substrate at each position where a constant-potential wire and the image-signal wire intersect each other when seen in a direction perpendicular to the surface of the substrate. A major feature of this device is that the image-signal wire is electrically connected to a first terminal of a switching element in the electrostatic protection circuit, and the constant-potential wire is electrically connected to a second terminal of the switching element.

The electro-optical device disclosed in JP-A-2001-339065, however, has a technical problem in that unintentional capacitive coupling may occur because the short-circuit wire has portions thereof being not electrically connected to any other wires, that is, the portions of the short-circuit wire are in a so-called floating state. Particularly, if any unintentional capacitive coupling occurs between the floating portions of the short-circuit wire and data lines that supply image signals, display failure may occur. On the other hand, the electro-optical device disclosed in JP-A-2005-309003 has another technical problem in that it is difficult to prevent damage to TFTs brought by static electricity generated during the process of manufacturing the electro-optical device.

SUMMARY

An advantage of some aspects of the invention is that it provides an electro-optical device in which the occurrence of unintentional capacitive coupling due to cut portions of a short-circuit wire can be suppressed, and an electronic apparatus including such an electro-optical device.

According to a first aspect of the invention, an electro-optical device includes, on a substrate, a plurality of scanning lines; a plurality of data lines intersecting the scanning lines; a plurality of pixel electrodes provided in correspondence with intersections of the scanning lines and the data lines; a short-circuit wire provided in a peripheral area surrounding a pixel area in which the pixel electrodes are provided, the short-circuit wire including a main portion that short-circuits the scanning lines with each other in a manufacturing process and an extending portion that extends from the main portion in such a manner as to intersect the data lines; and a constant-potential wire supplied with a predetermined potential and electrically connected to the extending portion.

In the electro-optical device according to the first aspect of the invention, the scanning lines and the data lines intersect each other on the substrate, such as a quartz substrate, and the pixel electrodes are provided in correspondence with intersections of the scanning lines and the data lines. The short-circuit wire is provided in the peripheral area surrounding the pixel area in which the pixel electrodes are provided, and includes the main portion that short-circuits the scanning lines with each other in the process of manufacturing the electro-optical device and the extending portion that extends from the main portion in such a manner as to intersect the data lines. The “pixel area” denotes the entirety of an area in which the pixels are arranged two-dimensionally, not an area occupied by each of the pixels, and typically corresponds to an “image display area” or a “display area”. In the pixel area, a plurality of pixel electrodes are provided in a matrix pattern, for example.

In a typical manufacturing process, the short-circuit wire is provided in the same layer as the scanning lines. Further, when the data lines are formed in the manufacturing process, for example, electrical connection between the short-circuit wire and the scanning lines and electrical connection between the main portion and the extending portion of the short-circuit wire are cut simultaneously. In this context, to “short-circuit the scanning lines with each other in a manufacturing process” means that the scanning lines are electrically connected to each other temporarily in the manufacturing process, but the short-circuit wire and the scanning lines are not electrically connected to each other in the electro-optical device obtained as a finished product.

The constant-potential wire is supplied with a predetermined potential and is electrically connected to the extending portion of the short-circuit wire. The “predetermined potential” in the first aspect of the invention means a potential that is constant at least during each of predetermined periods, regardless of the information contained in image signals to be supplied to the data lines. For example, like an earthing potential, i.e., a ground potential, the “predetermined potential” may be a potential that is completely fixed at a certain level with respect to the time axis. Alternatively, like a common potential, i.e., a counter-electrode potential, the “predetermined potential” may be a potential that is fixed at respective levels for a plurality of periods with respect to the time axis. Specifically, the potential may be fixed at a first level in each of odd field-time periods of the image signal, and at a second level in each of even field-time periods, for example.

According to a study made by the present inventor, since cut portions of the short-circuit wire are not electrically connected to any other wires, the cut portions may trigger unintentional capacitive coupling. The study also shows that, particularly in a case where the cut portions of the short-circuit wire intersect the data lines, problems including nonuniformity between lines may occur, resulting in deterioration of image quality.

Hence, in the first aspect of the invention, the extending portion of the short-circuit wire and the constant-potential wire are electrically connected to each other. This determines the potential of the extending portion, whereby the occurrence of unintentional capacitive coupling can be suppressed. Accordingly, adverse influence of unintentional capacitive coupling on, for example, image signals to be supplied to the data lines can be suppressed. Consequently, deterioration of image quality can be suppressed.

In the electro-optical device according to the first aspect of the invention, it is preferable that the constant-potential wire have at least a portion thereof overlapping the extending portion in plan view of the substrate.

In this case, since the constant-potential wire and the extending portion are electrically connected to each other, there is no need to separately provide wires or the like for making connection therebetween. This reduces the size of the electro-optical device and enables relatively easy establishment of electrical connection between the constant-potential wire and the extending portion, providing a great advantage in practical use.

The electro-optical device according to the first aspect of the invention further includes dummy wires provided in a region of the peripheral area in such a manner as to be interposed between adjacent ones of the data lines, the dummy wires being obtained from a same film as the data lines. Further, it is preferable that the constant-potential wire be provided in an upper layer relative to the data lines with a first insulating film interposed therebetween and be electrically connected to the dummy wires via first contact holes provided in the first insulating film. Furthermore, it is preferable that the extending portion be provided in a lower layer relative to the data lines with a second insulating film interposed therebetween and be electrically connected to the dummy wires via second contact holes provided in the second insulating film.

In this case, the dummy wires are provided in a region of the peripheral area in such a manner as to be interposed between the data lines. The dummy wires are obtained from the same film as the data lines, that is, the dummy wires are provided in a layer having the data lines. Thus, the leakage of light from regions between the data lines can be suppressed and therefore deterioration of image quality can be suppressed. The “same film” implies that the dummy wires and the data lines are composed of the same conductive material and are formed simultaneously in respective patterns.

According to a second aspect of the invention, an electronic apparatus includes the electro-optical device according to the first aspect of the invention (including the preferable configurations thereof).

Since the electronic apparatus according to the second aspect of the invention includes the electro-optical device according to the first aspect of the invention, the electronic apparatus can suppress the occurrence of unintentional capacitive coupling. Consequently, various electronic apparatuses capable of displaying high-quality images can be provided, such as a projection display apparatus, a mobile phone, an electronic organizer, a word processor, a view-finder-type or monitor-direct-view-type videotape recorder, a workstation, a videophone, a point-of-sale (POS) terminal, and other apparatuses having touch panels.

Other features and advantages of the invention will become apparent from the following description of exemplary embodiments.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Embodiments of the electro-optical device and the electronic apparatus according to the invention will now be described with reference toFIGS. 1 to 6. Relevant layers and members shown in the drawings are not to scale for easier recognition. The embodiments will be described taking an active-matrix liquid crystal device including a drive circuit, as an exemplary electro-optical device.

First, the overall configuration of a liquid crystal device according to an embodiment of the invention will be described with reference toFIGS. 1 and 2.FIG. 1is a plan view showing an element substrate and relevant elements provided thereon, seen from a side of a counter substrate.FIG. 2is a cross-sectional view taken along the line II-II inFIG. 1.

Referring toFIGS. 1 and 2, a liquid crystal panel100of the liquid crystal device according to the embodiment includes an element substrate10and a counter substrate20facing each other. The element substrate10is any of a quartz substrate, a glass substrate, a silicon substrate, and the like. The counter substrate20is any of a quartz substrate, a glass substrate, and the like. The element substrate10and the counter substrate20in combination hold a liquid crystal layer50therebetween by being bonded to each other with a sealant52provided in a sealing area surrounding an image display area10a.

The sealant52is composed of a material for bonding the substrates10and20together, such as ultraviolet curable resin, thermosetting resin, or ultraviolet-heat curable resin. In a manufacturing process, the sealant52is applied to the element substrate10and is then cured with ultraviolet, heat, or the like applied thereto. The sealant52contains gap materials, such as glass fibers or glass beads, that are dispersed therein so as to control the interval, i.e., the gap, between the element substrate10and the counter substrate20to be a predetermined length. In addition to or in replacement of mixing the gap materials in the sealant52, gap materials may be provided in the image display area10aor in a peripheral area surrounding the image display area10a.

Referring toFIG. 1, a light-shielding film frame53that defines the image display area10ais provided on the counter substrate20, along the inner periphery of the sealing area having the sealant52. Part of or the entirety of the light-shielding film frame53may be provided as an internal light-shielding film in the element substrate10.

A data line driving circuit101and external circuit connection terminals102are provided in a portion, along one side of the element substrate10, of the peripheral area outside the sealing area having the sealant52. A sampling circuit7is provided on an inner side of the sealing area along the one side of the element substrate10in such a manner as to be covered with the light-shielding film frame53. Scanning line driving circuits104are provided in regions of a frame area, inside the sealing area, along two sides connected to the one side of the element substrate10in such a manner as to be covered with the light-shielding film frame53.

The element substrate10is provided with vertical conduction terminals106at positions facing four corners of the counter substrate20. The vertical conduction terminals106in combination with vertical conductors107connect the element substrate10and the counter substrate20, thereby providing electrical conduction therebetween. The element substrate10is also provided with routing wires90that electrically connect the external circuit connection terminals102to the data line driving circuit101, the scanning line driving circuits104, the vertical conduction terminals106, and so forth.

Referring toFIG. 2, the element substrate10has thereon a layered structure in which pixel-switching transistors, as driving elements, and wires including scanning lines and data lines are provided in respective layers. Although details of the configuration of the layered structure are omitted inFIG. 2, island-shaped pixel electrodes9acomposed of a transparent material, such as indium tin oxide (ITO), are provided on the layered structure in a predetermined pattern in correspondence with pixels.

The pixel electrodes9aare provided in the image display area10aon the element substrate10in such a manner as to face a counter electrode21, which will be described separately below. A surface of the element substrate10near the liquid crystal layer50, i.e., the surface including the pixel electrodes9a, is covered with an alignment film16.

A surface of the counter substrate20near the element substrate10is provided with a light-shielding film23. The light-shielding film23is provided in a matrix pattern, for example, in plan view seen in a direction perpendicular to the surface of the counter substrate20. Regions of the counter substrate20covered with the light-shielding film23are defined as non-open regions. Regions of the counter substrate20not covered with the light-shielding film23are defined as open regions that allow light emitted from a lamp of a projector or a backlight of a direct-view apparatus, for example, to be transmitted therethrough. Alternatively, the light-shielding film23may be provided in a stripe pattern. In such a case, non-open regions may be defined by utilizing, in combination with the light-shielding film23, various elements provided on the element substrate10, including the data lines.

The counter electrode21composed of a transparent material such as ITO is provided over the light-shielding film23in such a manner as to face the pixel electrodes9a.To realize color display in the image display area10a,color filters (not shown inFIG. 2) may also be provided over the light-shielding film23in regions overlapping the respective open regions and part of the non-open regions therearound. The counter electrode21provided on the surface of the counter substrate20near the element substrate10is covered with an alignment film22.

The element substrate10shown inFIGS. 1 and 2having the data line driving circuit101, the scanning line driving circuits104, the sampling circuit7, and so forth may also have the following: a precharge circuit that supplies precharge signals of predetermined voltage levels to the respective data lines prior to image signals, an inspection circuit that inspects the quality, defects, or the like of the liquid crystal device in the manufacturing process or at the time of shipment, and so forth.

Next, the electrical configuration of the liquid crystal device according to the embodiment will be described with reference toFIG. 3.FIG. 3is a block diagram schematically showing the electrical configuration of the liquid crystal device according to the embodiment.

Referring toFIG. 3, a plurality of scanning lines11aand a plurality of data lines6aare provided in the image display area10aon the element substrate10in such a manner as to intersect each other. Pixel units9, which correspond to the pixels, are provided at respective intersections of the scanning lines11aand the data lines6a, thereby forming a matrix pattern. The pixel units9are each electrically connected to one of the scanning lines11aand one of the data lines6a. Basically, the pixel units9each include a pixel-switching transistor for selectively supplying an image signal supplied via the data line6a, and a pixel electrode9a(seeFIG. 2) serving, in combination with the counter electrode21(seeFIG. 2), as a liquid crystal retention capacitor that supplies the image signal that has been input thereto to the liquid crystal layer50(seeFIG. 2) and retains the image signal in the liquid crystal layer50. To prevent the leakage of the image signal retained in the liquid crystal retention capacitor, the pixel unit9may also include a storage capacitor provided in parallel with the liquid crystal retention capacitor.

Referring toFIG. 3, the element substrate10has in the peripheral area thereof the data line driving circuit101, the sampling circuit7, and the scanning line driving circuits104. In addition, a short-circuit wire700lies in the peripheral area. In the process of manufacturing the liquid crystal panel100, the short-circuit wire700temporarily short-circuits the scanning lines11afrom each other, but is subsequently cut at required positions C, for example, when the data lines6aor the like are formed. Thus, the electrical connections between the short-circuit wire700and the scanning lines11aare cut.

In the embodiment, portions of the short-circuit wire700extending along the left and right sides, inFIG. 3, of the element substrate10(i.e., in a Y direction) are each an example of the “main portion” according to the invention, and a portion of the short-circuit wire700extending along the lower side, inFIG. 3, of the element substrate10is an example of the “extending portion” according to the invention.

The scanning line driving circuits104are supplied with a Y clock signal CLY (and an inverse Y clock signal CLYinv obtained by inversing the Y clock signal CLY) and a Y start pulse DY from an external circuit (not shown) or the like via corresponding ones of the external circuit connection terminals102(seeFIG. 1). When the Y start pulse DY is input to the scanning line driving circuits104, the scanning line driving circuits104generate scanning signals sequentially with timings based on the Y clock signal CLY and the inverse Y clock signal CLYinv and output the scanning signals to the respective scanning lines11a.

The data line driving circuit101is supplied with an X clock signal CLX (and an inverse X clock signal CLXinv obtained by inversing the X clock signal CLX) and an X start pulse DX from the external circuit via corresponding ones of the external circuit connection terminals102. When the X start pulse DX is input to the data line driving circuit101, the data line driving circuit101generates sampling signals S1, . . . , Sn sequentially with timings based on the X clock signal CLX and the inverse X clock signal CLXinv and output the sampling signals S1, . . . , Sn to respective sampling signal lines.

The sampling circuit7includes switching elements (i.e., sampling switches) provided in correspondence with the data lines6aso as to select appropriate ones of the data lines6ato be supplied with the image signals from six image signal lines6. The timing of switching the switching elements is controlled in accordance with the sampling signals S1, . . . , Sn supplied from the data line driving circuit101.

The sampling circuit7is supplied with image signals VID1to VID6obtained by serial-parallel conversion into six phases, i.e., six-phase expansion, performed by the external circuit, via the six image signal lines6. The six image signal lines6are routed from corresponding ones of the external circuit connection terminals102, around the data line driving circuit101, and extend in a direction in which the data lines6aare arranged (i.e., in an X direction).

The number of phases into which the image signal is expanded (i.e., the number of lines for serial-parallel expansion of the image signal) is not limited to six, and may be nine, twelve, twenty-four, forty-eight, ninety-six, and so forth.

The timing signals including the clock signals CLX and CLY are generated by a timing generator included in the external circuit (not shown) or the like, and are supplied via the corresponding external circuit connection terminals102to the circuits provided on the element substrate10. Power, for example, required for driving the driving circuits is also supplied from the external circuit or the like.

The element substrate10has in the peripheral area thereof a counter-electrode-potential wire605, which is an example of the “constant-potential wire” according to the invention, via which a counter-electrode potential LCC is supplied from the external circuit or the like. The counter-electrode-potential wire605is routed from one of the external circuit connection terminals102to one of the vertical conduction terminals106, extends therefrom to another vertical conduction terminal106in the direction in which the data lines6aare arranged (i.e., in the X direction), and is routed therefrom to another external circuit connection terminal102.

Thus, the counter-electrode potential LCC is supplied via the two vertical conduction terminals106and corresponding ones of the vertical conductors107(seeFIG. 1) to the counter electrode21. The counter-electrode potential LCC is regarded as a reference potential of the counter electrode21. With the counter-electrode potential LCC, the potential differences between the counter electrode21and the pixel electrodes9aare appropriately retained, whereby the liquid crystal retention capacitors are obtained. In the embodiment, a 1H inversion driving method is employed. The image signals VID1to VID6are inverted in a predetermined cycle between positive polarity, exhibiting a potential higher than the counter-electrode potential LCC, and negative polarity, exhibiting a potential lower than the counter-electrode potential LCC. More specifically, when display of one frame is performed, the image signals VID1to VID6are supplied with a positive potential, with reference to the counter-electrode potential LCC, to the pixel units9arranged in odd lines, and with a negative potential, with reference to the counter-electrode potential LCC, to the pixel units9arranged in even lines. Conversely, when display of a subsequent frame is performed, the image signals VID1to VID6are supplied with a positive potential to the pixel units9arranged in the even lines, and with a negative potential to the pixel units9arranged in the odd lines. That is, the potential polarities of the image signals VID1to VID6are inverted in such a manner that the pixel units9arranged in the same line are supplied with potentials of the same polarity, while the pixel units9arranged in different lines adjacent to each other are supplied with potentials of different polarities, and such polarities of the potentials supplied to the respective lines are inverted for each frame cycle.

A major feature of the embodiment is that a portion of the short-circuit wire700extending along the lower side, inFIG. 3, of the element substrate10is electrically connected to the counter-electrode-potential wire605via, for example, contact holes710. This determines the potential of the short-circuit wire700, whereby the occurrence of unintentional capacitive coupling can be suppressed. Accordingly, nonuniformity between lines can be suppressed, and therefore deterioration of image quality can also be suppressed.

Next, the positional relationship between the data lines6a, the short-circuit wire700, and the counter-electrode-potential wire605will be specifically described with reference toFIGS. 4 and 5.FIG. 4is a plan view showing the data lines6a, the short-circuit wire700, and the counter-electrode-potential wire605seen from the side of the counter substrate20.FIG. 5is a cross-sectional view taken along the line V-V inFIG. 4. InFIG. 5, elements residing above the counter-electrode-potential wire605and elements residing below the short-circuit wire700are omitted.

Referring toFIG. 4, the counter-electrode-potential wire605spreads over the short-circuit wire700in plan view. In other words, the short-circuit wire700extends in a region where the counter-electrode-potential wire605spreads.

The data lines6aeach intersect the short-circuit wire700. The data lines6aare electrically connected at lower ends thereof inFIG. 4to the sampling circuit7(seeFIG. 3) and at upper ends thereof to the pixel units9(seeFIG. 3). Dummy wires201and202are alternately provided between adjacent ones of the data lines6a. The dummy wires201and202contribute to suppression of the leakage of light from regions between the data lines6a. Thus, deterioration of image quality can be suppressed.

Referring toFIG. 5, a layer having the data lines6aand the dummy wires201and202is held between a layer having the short-circuit wire700and a layer having the counter-electrode-potential wire605.

The short-circuit wire700is composed of conductive polysilicon film and is formed simultaneously with, for example, the scanning lines11aor gate electrodes provided in the image display area10a, in respective patterns. The dummy wires201and202are composed of metal film or alloy film, such as aluminum film, or any light-shielding conductive film of other kinds, and are formed simultaneously with the data lines6aprovided in the image display area10a, in respective patterns. The counter-electrode-potential wire605is composed of metal film or alloy film, such as aluminum film, or any light-shielding conductive film of other kinds, and is formed simultaneously with a shielding layer, in respective patterns. The shielding layer is provided between the data lines6aand the pixel electrodes9ain the image display region10a, and is supplied with a predetermined potential.

An interlayer insulating film41is provided between the layer having the short-circuit wire700and the layer having the data lines6aand so forth. An interlayer insulating film42is provided between the layer having the data lines6aand so forth and the layer having the counter-electrode-potential wire605. The interlayer insulating films41and42prevent the occurrence of short circuits between the foregoing elements. The interlayer insulating films41and42according to the embodiment are examples of the “second insulating film” and the “first insulating film”, respectively, according to the invention.

Referring toFIG. 5, the counter-electrode-potential wire605is electrically connected to the short-circuit wire700via, in sequence, contact holes710bprovided in the interlayer insulating film42, the dummy wires201or202, and contact holes710aprovided in the interlayer insulating film41.

Electronic Apparatus

Next, another embodiment of the invention in which the liquid crystal device described above is applied to a projector, an example of an electronic apparatus, will be described with reference toFIG. 6. The liquid crystal panel100of the liquid crystal device described above is used as a light valve of the projector.FIG. 6is a plan view showing an exemplary configuration of the projector.

Referring toFIG. 6, a projector1100has therein a lamp unit1102including a white-light source such as a halogen lamp. Light emitted from the lamp unit1102is split into rays of three primary colors of red (R), blue (B), and green (G) by four mirrors1106and two dichroic mirrors1108all provided in a light guide1104. The split rays of light enter respective liquid crystal panels1110R,1110B, and1110G serving as light valves for the respective colors.

The liquid crystal panels1110R,1110B, and1110G each have substantially the same configuration as the liquid crystal device described above, and are driven in accordance with signals for the colors of R, B, and G, respectively, supplied from an image signal processing circuit. The rays of light modulated by the liquid crystal panels1110R,1110B, and1110G enter a dichroic prism1112in three respective directions. The dichroic prism1112refracts the rays of R and B by 90 degrees but allows the ray of G to travel straight therethrough. Thus, monochrome images of the three respective colors are integrated, whereby a three-color image is projected through a projection lens1114onto a screen or the like.

Focusing on the respective images displayed by the liquid crystal panels1110R,1110B, and1110G, the images displayed by the liquid crystal panels1110R and1110B need to be flipped horizontally with respect to the image displayed by the liquid crystal panel1110G.

The liquid crystal panels1110R,1110B, and1110G do not require color filters because the rays applied thereto already have the respective colors of R, B, and G with the aid of the dichroic mirrors1108.

Examples of the electronic apparatus described with reference toFIG. 6include a mobile personal computer, a mobile phone, a liquid crystal television, a viewfinder-type or monitor-direct-view-type videotape recorder, a car navigation system, a pager, an electronic organizer, a calculator, a word processor, a workstation, a videophone, a point-of-sale (POS) terminal, and other apparatuses having touch panels. Needless to say, the invention can be applied to any of the foregoing electronic apparatuses.

The invention is not limited to the embodiments described above, and changes can be appropriately made thereto without departing from the scope and idea of the invention that can be understood from the appended claims and the entirety of the specification. Electro-optical devices to which such changes have been made and electronic apparatuses having such electro-optical devices are also included in the technical scope of the invention.