JP2006095387A - Dust removing device, dust removing device for electrooptical apparatus, dust removing method, electrooptical apparatus and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dust removing device, for example, provided to an electrooptical apparatus to easily the dust or the like bonded to a substrate. <P>SOLUTION: In the electrooptical apparatus which has a substrate and displays an image on the image display region on the substrate electrooptically, the dust removing device for the electrooptical apparatus for removing the dust on the surface of the substrate is equipped with an elastic wave producing part for producing an elastic surface wave advancing along the surface of the substrate in the image display region and a wiring or electrode part for driving the elastic wave producing part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a dust removal device that removes dust such as dust from the surface of a substrate such as glass by surface acoustic waves, a dust removal device for an electro-optical device used in an electro-optical device such as a liquid crystal device, and dust removal. The present invention relates to a technical field of a method, an electro-optical device including such a dust removing device, and an electronic apparatus such as a liquid crystal projector.

  Patent Document 1 discloses a projector that uses, for example, a liquid crystal device, which is an electro-optical device, as a light valve. In such a projector, an image is displayed by administering a display image displayed in the image display area in the electro-optical device, for example, on a screen by a projection lens. Here, the focus of the projection lens is adjusted to a predetermined position in the liquid crystal, which is an electro-optical material sandwiched between a pair of substrates, for example, in an electro-optical device. Therefore, in the electro-optical device, when dust such as dust adheres to the image display area on one of the pair of substrates, the projection lens is focused on the dust, and the display image on the screen is displayed. There is a risk that trash will be reflected.

  For this reason, in the electro-optical device, for example, dust-proof glass is attached to the substrate. If comprised in this way, it can prevent that dust is reflected in the display image on a screen clearly by the defocusing effect | action of dustproof glass.

  Patent Document 2 discloses a photoelectric conversion element for converting an optical image of a subject into an electric signal and a sealing structure for sealing a space including the photoelectric conversion element in a camera. The hermetically sealed structure is provided with a glass plate that is incident on the imaging surface of the photoelectric conversion element and transmits an imaging light beam that forms an optical image on the imaging surface. In addition, vibration means is provided for vibrating the glass plate by bulk vibration to remove dust adhering to the surface from the imaging light beam passage range.

JP 2002-244214 A JP 2002-204379 A

  However, even if dust-proof glass is provided, if image display is performed with high contrast on the screen, dust attached to the electro-optical device may be clearly reflected as described above. In this case, even if an attempt is made to further increase the thickness of the dust-proof glass to prevent the reflection of dust, it cannot be a practical measure due to space restrictions in the projector. Even if the dust-proof glass is made thick in this way, in addition to the new problem that the cooling efficiency of the electro-optical device is reduced, the following light leakage cannot be prevented. That is, when a high gradation display screen, that is, a dark screen is displayed on the screen, the light incident on the electro-optical device through the polarizing plate is locally polarized or refracted by dust, and polarized. If the state changes, light leakage may occur.

  As another countermeasure against the above problems, in order to prevent dust from adhering to the electro-optical device, in the projector, for example, a filter is installed at the inlet of the cooling air supplied to the electro-optical device, The projector body may be assembled in a clean room. However, these other measures have new problems such as troublesome work required for the measures and reduced cooling efficiency.

  The present invention has been made in view of the above-described problems. For example, a dust removing device and a dust removing method that are provided in an electro-optical device and can easily remove dust, dust, and the like attached on a substrate, It is an object of the present invention to provide an electro-optical device including such a dust removing device and various electronic apparatuses including the electro-optical device.

  In order to solve the above-described problem, an electro-optical device dust removing device of the present invention includes a substrate, and the electro-optical device displays an image electro-optically in an image display area on the substrate. A dust removing device for an electro-optical device that removes dust, an elastic wave generating unit that generates a surface acoustic wave that travels along the surface of the substrate in the image display region, and drives the elastic wave generating unit Wiring or an electrode part.

  In the electro-optical device main body from which dust is removed by the electro-optical device dust removing device of the present invention, for example, a pair of substrates that sandwich liquid crystal as an electro-optical material is provided. In the image display region, for example, light incident from a light source is modulated by applying a voltage corresponding to the image signal to the electro-optic material for each pixel. The light modulated by the electro-optical material is emitted as display light, whereby image display is performed.

  For example, the elastic wave generator is provided on the substrate surface opposite to the side facing the electro-optical material in at least one of the pair of substrates. Alternatively, in the main body portion of the electro-optical device, it is provided on the surface opposite to the side facing the main body portion of a substrate such as dust-proof glass provided by being bonded to at least one of the pair of substrates. The elastic wave generating unit is driven by driving means via a wiring or an electrode unit. Such a driving unit may be provided in the electro-optical device as a part of the dust removing device, or may be provided separately from the dust removing device or as a part of the dust removing device by external attachment or the like. It may be attached to.

  The driven elastic wave generator generates a surface acoustic wave. The surface acoustic wave generated by the elastic wave generator travels along the surface of the substrate in the image display area of the electro-optical device. Accordingly, dust such as dust or dust existing on the substrate surface can be moved and removed from the image display area in the image display area. In particular, based on the size and type of dust to be removed, the ease of dropping on the substrate surface, the image quality required by the specifications, etc., surface acoustic waves are generated with a strength that can remove dust as much as necessary. Thus, it can be removed from the image display area.

  Therefore, according to the dust removing device for an electro-optical device of the present invention, dust can be easily removed by driving the elastic wave generating unit. Therefore, it is possible to prevent dust from appearing in the display image displayed by the electro-optical device. Further, it is possible to prevent the polarization state of the light incident on the electro-optical device through the polarizing plate from being changed by dust existing in the light path. For this reason, when a high gradation display image is displayed by the electro-optical device, it is possible to prevent light leakage. As a result, high-quality image display can be performed by the electro-optical device.

  Here, in the electro-optical device, for example, a pixel electrode for applying a voltage to the electro-optical material on one side of the pair of substrates facing the electro-optical material, and a thin film transistor (for driving the pixel electrode) A laminated structure in which a drive element such as a thin film transistor (hereinafter referred to as “TFT”) is formed is formed. If the substrate surface is vibrated by the bulk vibration disclosed in Patent Document 2, the substrate is bent by the vibration, so that a crack is formed in the semiconductor layer included in the above-described stacked structure, for example, constituting at least a part of the driving element. Is likely to occur. That is, if the bulk vibration technique of Patent Document 2 is applied to this type of electro-optical device, the main part of the electro-optical device such as a semiconductor element is damaged due to the occurrence of cracks or the like before dust removal. It will be done.

  In contrast, the electro-optical device dust removing device of the present invention vibrates the substrate surface with surface acoustic waves, thereby preventing the substrate from being bent and removing dust without damaging the laminated structure. Is possible.

  In the projector, for example, three types of light valves for red (R), green (G), and blue (B) are provided to perform color display. When the electro-optical device is used as a light valve in such a projector, among the three types of light valves, particularly those that are disposed at positions where dust is particularly likely to adhere due to cooling air, or display images when dust is attached. It is preferable to perform dust removal with the dust removing device for an electro-optical device according to the present invention for those that are likely to affect the above. In this way, it is possible to prevent the quality of the display image from deteriorating without performing dust removal with the dust removing device of the present invention for all three types of light valves.

  In one aspect of the dust removing device for an electro-optical device according to the present invention, the elastic wave generation unit is disposed in a peripheral region located around the image display region on the substrate, and the image display is performed from the peripheral region. The surface acoustic wave is generated so as to travel to the region.

  According to this aspect, the elastic wave generator can be provided without changing the size of the substrate or the image display area. The elastic wave generating unit generates a surface acoustic wave that travels along the surface of the substrate from the peripheral region toward the image display region. This makes it possible to remove dust existing in the image display area on the substrate surface by moving the image display area to the peripheral area. At this time, it is very advantageous because the elasticity generating portion does not interfere with the image displayed in the image display area regardless of whether or not the elasticity generating portion is made of a transparent member.

  In the aspect in which the elastic wave generation unit is disposed in the peripheral region, the elastic wave generation unit may be configured to be provided along one side of the image display region.

  If comprised in this way, it will become possible to remove the dust which exists in this image display area in the image display area by moving it in one direction from the image display area to the peripheral area by the surface acoustic wave. In this case, the elastic wave generator does not necessarily generate a surface acoustic wave that travels in only one direction. For example, a surface acoustic wave that travels in one direction from the peripheral region to the image display region and in both directions opposite to this direction may be generated in the elastic wave generation unit.

  For example, when an electro-optical device is used as a light valve of a projector, an elastic wave generator is provided so that surface acoustic waves are preferentially advanced in a direction in which dust easily moves in accordance with the layout of the light valve of the projector. It is good to. If comprised in this way, it will become possible to perform dust removal more reliably and efficiently. For example, according to the layout of the light valve, along the side of the image display area so that the surface acoustic wave preferentially travels in the direction corresponding to gravity on the substrate surface or in the same direction as the cooling air flows. An elastic wave generator is provided.

  Further, in an aspect in which the elastic wave generation unit is disposed in the peripheral region, the elastic wave generation unit may be configured to be provided along two sides of the image display region.

  According to this configuration, by driving both of the elastic wave generators provided along the two sides of the image display area, dust existing in the image display area is surrounded by the surface acoustic wave from the image display area. It can be removed by moving in two directions toward the region. Alternatively, a surface acoustic wave is generated by selectively driving one of the elastic wave generation units provided along the two sides of the image display area, and is directed in one direction from the image display area to the peripheral area. Garbage can be moved and removed.

  For example, in a projector, if surface acoustic waves that travel in a direction in which dust easily moves are preferentially generated in accordance with the layout of the electro-optical device that is a light valve, dust removal can be performed more reliably and efficiently. Can be done.

  Further, in an aspect in which the elastic wave generating unit is arranged in the peripheral region, the elastic wave generating unit includes a piezoelectric film formed along at least one side of the image display region, and the piezoelectric film from the peripheral region on the piezoelectric film. And at least two kinds of electrodes arranged along the direction toward the image display region, and a comb-tooth electrode extending along the arrangement direction, and extending in the extension direction of the comb-tooth electrode You may comprise so that it may have a piezoelectric element which produces | generates the said surface acoustic wave which advances along.

  When configured in this manner, a surface acoustic wave can be generated in the piezoelectric film by applying a predetermined electric field by the comb-teeth electrode when the elastic wave generator is driven. The surface acoustic wave travels in the direction from the peripheral region toward the image display region along the extending direction of the comb-tooth electrode. A surface acoustic wave traveling in a direction opposite to this direction may be generated by the piezoelectric element.

  In this aspect in which the elastic wave generating unit includes a piezoelectric element, the piezoelectric element preferentially travels in one direction from the peripheral area toward the image display area along the extending direction of the comb electrode. You may comprise so that a surface wave may be produced | generated.

  If comprised in this way, in an elastic wave generation part, it will become possible to utilize the surface acoustic wave which generate | occur | produced in the piezoelectric element for dust removal without waste. In other words, in addition to the surface acoustic wave that travels in one direction from the peripheral region to the image display region, the surface acoustic wave that travels in the opposite direction is generated by the piezoelectric element. The surface acoustic wave to be used is not used for dust removal. In this case, half of the electric power for driving the elastic wave generator is wasted. On the other hand, in this aspect, it is possible to use the power for driving the elastic wave generating unit without waste.

  Further, in an aspect in which the acoustic wave generating unit includes a piezoelectric element, the piezoelectric element may be configured to generate the surface acoustic wave having a predetermined frequency capable of removing the dust.

  If comprised in this way, it will become possible to generate a surface acoustic wave with the intensity | strength which can remove dust as much as needed. In particular, if the frequency is low, the amplitude of the surface acoustic wave becomes large, so that it is possible to remove dust from, for example, the substrate surface with the surface acoustic wave having a relatively high strength. In order to decrease the frequency, the wavelength of the surface acoustic wave may be increased by widening the pitch of the comb electrodes.

  However, when the frequency of the surface acoustic wave is changed in this way, the value of the electromechanical coupling coefficient also changes. The electromechanical coupling coefficient is adjusted by adjusting the wavelength of the surface acoustic wave or the film thickness of the piezoelectric film. Therefore, when changing the frequency of the surface acoustic wave, it is preferable to adjust the value of the electromechanical coupling coefficient in consideration of the thickness of the piezoelectric film. In this way, the surface acoustic wave can be generated with a strength that can remove dust more reliably. Therefore, dust can be removed by more efficiently using the power for driving the elastic wave generator.

  Further, in an aspect in which the elastic wave generating unit includes a piezoelectric element, the piezoelectric element is configured to generate the surface acoustic waves having a plurality of types of frequencies corresponding to the size of the dust for each value of the frequency. May be.

  With this configuration, among the dusts existing on the substrate surface in the image display area of the electro-optical device, it is possible to remove the dusts of a plurality of types by moving the surface acoustic waves having the corresponding frequencies. Become.

  In addition, in the aspect in which the elastic wave generating unit is disposed in the peripheral region, the substrate is provided as a defocus glass, a cover glass, or a dust-proof glass in the main unit of the electro-optical device, and the main unit of the substrate The dust may be removed on the surface opposite to the side facing the surface.

  If comprised in this way, it will become possible to prevent the reflection of the dust in a display image also by the defocusing effect | action of the board | substrate provided as defocus glass, a cover glass, or dustproof glass.

  In the aspect in which the elastic wave generating unit is disposed in the peripheral region, the substrate is provided in the main body of the electro-optical device as one of the pair of substrates that sandwich the electro-optical material, The dust may be removed on the surface of one substrate opposite to the side facing the electro-optical material.

  According to this structure, it is possible to prevent dust from being reflected in the display image without removing defocus glass, cover glass, or dust-proof glass by removing dust with the dust removing device. . Therefore, in this case, the electro-optical device can be reduced in thickness or size.

  In order to solve the above problems, an electro-optical device according to the present invention includes the above-described dust removing device for an electro-optical device according to the present invention (including various aspects thereof).

  According to the electro-optical device of the present invention, since the electro-optical device dust removing device of the present invention as described above is provided, high-quality image display can be performed in the image display region.

  In order to solve the above problems, an electronic apparatus according to the present invention includes the above-described electro-optical device according to the present invention.

  Since the electronic apparatus of the present invention includes the above-described electro-optical device of the present invention, a projection display device, a television, a mobile phone, an electronic notebook, a word processor, a view capable of performing high-quality image display. Various electronic devices such as a finder type or a monitor direct-view type video tape recorder, a workstation, a videophone, a POS terminal, and a touch panel can be realized. Further, as an electronic apparatus of the present invention, for example, an electrophoretic device such as electronic paper, an electron emission device (Field Emission Display and a Conduction Electron-Emitter Display), an electrophoretic device, and an apparatus using the electron emission device, DLP (Digital Light Processing) and the like can also be realized.

  In order to solve the above problems, a dust removing device of the present invention is a dust removing device that removes dust on the surface of a substrate, and includes an elastic wave generator that generates a surface acoustic wave that travels along the surface of the substrate. And a wiring or an electrode part for driving the elastic wave generating means.

  According to the dust removing device of the present invention, dust such as dust or dust existing on the substrate surface is removed by the surface acoustic wave generated by the elastic wave generating unit, similarly to the above-described dust removing device for an electro-optical device of the present invention. It can be moved and removed from the substrate surface.

  In order to solve the above problems, an electro-optical device dust removing method of the present invention includes a substrate, and the electro-optical device displays an image electro-optically in an image display area on the substrate. A method for removing dust from an electro-optical device, wherein a step of driving an elastic wave generator that generates a surface acoustic wave that travels along the surface of the substrate in the image display region via a wiring or an electrode is provided. And generating the surface acoustic wave by the driven elastic wave generator.

  According to the dust removing method for an electro-optical device of the present invention, it is possible to perform high-quality image display in the electro-optical device, similar to the above-described dust removing device for an electro-optical device of the present invention.

  Such an operation and other advantages of the present invention will become apparent from the embodiments described below.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<1: Projector>
First, an embodiment of a liquid crystal projector as an example of an electronic apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing a practical configuration when an image is displayed by a liquid crystal projector, and FIG. 2 is a schematic sectional view showing a configuration example of the liquid crystal projector.

  In FIG. 1, for example, a personal computer (hereinafter referred to as a personal computer) 1 is connected to the liquid crystal projector 1100. Then, an image display is performed by the liquid crystal projector 1100 based on the image signal generated and supplied by the personal computer 1.

  FIG. 2 shows the configuration of the optical system incorporated in the optical unit of the liquid crystal projector 1100. The liquid crystal projector 1100 is constructed as a multi-plate color projector using three liquid crystal light valves as an example of an electro-optical device.

  The liquid crystal projector 1100 is configured as a projector using three liquid crystal light valves including an electro-optical device having a drive circuit mounted on a TFT array substrate and used as RGB light valves 600R, 600G, and 600B, respectively. . In the liquid crystal projector 1100, when projection light is emitted from a lamp unit 1102 of a white light source such as a metal halide lamp, light components R, G, and R corresponding to the three primary colors of RGB are obtained by three mirrors 1106 and two dichroic mirrors 1108. B is divided into light valves 600R, 600G and 600B corresponding to the respective colors. At this time, in particular, the B light is guided through a relay lens system 1121 including an incident lens 1122, a relay lens 1123, and an exit lens 1124 in order to prevent light loss due to a long optical path. The light components corresponding to the three primary colors modulated by the light valves 600R, 600G, and 600B are synthesized again by the dichroic prism 1112 and then projected as a color image on the screen via the projection lens 1114.

  As the light valves 600R, 600G, and 600B of the present embodiment, for example, an active matrix driving type liquid crystal device using TFTs as switching elements as described below is used. The liquid crystal device is provided with a dust removing device as will be described later.

  The liquid crystal projector 1100 is preferably provided with a sirocco fan (not shown in FIG. 2) for supplying cooling air to the three types of light valves 600R, 600G and 600B. Of the three types of light valves 600R, 600G, and 600B, particularly those that are disposed at positions where dust is likely to adhere due to the cooling air supplied as described above, and if dust adheres, the display image is likely to be affected. For the object, it is preferable to perform dust removal by the dust removal device of the present embodiment. In this way, it is possible to prevent deterioration in the quality of the display image without performing dust removal by the dust removal device for all three types of light valves 600R, 600G, and 600B. According to the study by the inventors of the present application, for example, in the light valve 600B for B, that is, the light valve 600B in which light having a wavelength near 435 nm is incident, by performing dust removal as described later, the display image can be effectively displayed. It is possible to prevent the deterioration of quality.

<2: Electro-optical device>
Next, the overall configuration of the embodiment of the electro-optical device according to the invention will be described with reference to FIGS. Here, a TFT active matrix driving type liquid crystal device with a built-in driving circuit, which is an example of an electro-optical device, is taken as an example. The electro-optical device according to this embodiment is used as the liquid crystal light valves 600R, 600G, and 600B in the liquid crystal projector 1100 described above.

  FIG. 3 is a plan view of the electro-optical device when the TFT array substrate is viewed from the counter substrate side together with each component formed thereon, and FIG. 4 is a cross-sectional view taken along line HH ′ of FIG. It is.

  3 and 4, in the electro-optical device according to the present embodiment, the TFT array substrate 10 and the counter substrate 20 are disposed to face each other. A liquid crystal layer 50 is sealed between the TFT array substrate 10 and the counter substrate 20, and the TFT array substrate 10 and the counter substrate 20 are provided with a sealing material 52 provided in a seal region positioned around the image display region 10a. Are bonded to each other.

  The sealing material 52 is made of, for example, an ultraviolet curable resin, a thermosetting resin, or the like for bonding the two substrates, and is applied on the TFT array substrate 10 in the manufacturing process and then cured by ultraviolet irradiation, heating, or the like. It is. Further, in the sealing material 52, a gap material such as glass fiber or glass beads for dispersing the distance (inter-substrate gap) between the TFT array substrate 10 and the counter substrate 20 to a predetermined value is dispersed. The gap material is not shown in FIGS. 3 and 4. That is, the electro-optical device according to the present embodiment is suitable for a small and enlarged display for a projector light valve.

  A light-shielding frame light-shielding film 53 that defines the frame area of the image display area 10a is provided on the counter substrate 20 side in parallel with the inside of the seal area where the sealing material 52 is disposed. However, part or all of the frame light shielding film 53 may be provided as a built-in light shielding film on the TFT array substrate 10 side.

  Of the peripheral area extending around the image display area 10 a, the data line driving circuit 101 and the external circuit connection terminal 102 are located on one side of the TFT array substrate 10 in the area located outside the seal area where the sealing material 52 is disposed. It is provided along. The scanning line driving circuit 104 is provided along two sides adjacent to the one side so as to be covered with the frame light shielding film 53. Further, in order to connect the two scanning line driving circuits 104 provided on both sides of the image display area 10a in this way, the TFT array substrate 10 is covered with the frame light shielding film 53 along the remaining side. A plurality of wirings 105 are provided.

  In addition, vertical conduction members 106 that function as vertical conduction terminals between the two substrates are disposed at the four corners of the counter substrate 20. On the other hand, the TFT array substrate 10 is provided with vertical conduction terminals in a region facing these corners. Thus, electrical conduction can be established between the TFT array substrate 10 and the counter substrate 20.

  In FIG. 3, on the TFT array substrate 10, an alignment film (not shown) is formed on the pixel electrode 9a after the pixel switching TFT, the scanning line, the data line and the like are formed. On the other hand, on the counter substrate 20, in addition to the counter electrode 21, a lattice-shaped or striped light-shielding film 23 and an alignment film (not shown) are formed in the uppermost layer portion. Further, the liquid crystal layer 50 is made of, for example, a liquid crystal in which one or several types of nematic liquid crystals are mixed, and takes a predetermined alignment state between the pair of alignment films.

  In addition, a dust-proof glass as described below, for example, is provided on the opposite side of the TFT array substrate 10 and the counter substrate 20 from the side facing the liquid crystal layer 50. FIG. 5 is a perspective view schematically showing a configuration of an electro-optical device provided with dust-proof glass.

  As shown in FIG. 5, in the main body 100 of the electro-optical device, as described above, the TFT array substrate 10 and the counter substrate each having various components formed on the substrates and bonded together to sandwich the liquid crystal layer 50. 20 is included. The main body 100 of the electro-optical device includes a dustproof glass 400 provided on each of the TFT array substrate 10 and the counter substrate 20.

  Here, when displaying an image on the liquid crystal projector 1100, the focus of the projection lens 1114 is adjusted to a predetermined position in the liquid crystal layer 50 of the electro-optical device, for example. At this time, due to the defocusing action of the dust-proof glass 400, dust or dirt attached to the outer surface of the dust-proof glass 400, that is, the surface of the dust-proof glass 400 opposite to the bonding surface with the TFT array substrate 10 or the counter substrate 20 is removed. The garbage will be displayed in a defocused state on the display screen on the screen. Further, a flexible substrate is connected to the external circuit connection terminal 102 and the wiring or electrode portion of the dust removing device provided on the substrate surface of the dust-proof glass 400, which is not shown in FIG. Is done.

  The dustproof glass 400 may be provided on either the TFT array substrate 10 or the counter substrate 20. Further, instead of or in addition to the dustproof glass 400, a defocus glass or a cover glass may be provided. Further, the main body 100 of the electro-optical device may include other optical elements such as an antireflection plate provided further outside the dustproof glass 400. Further, the polarizing plate and the retardation plate may be provided in the optical system of the liquid crystal projector 1100 or may be stacked on the surface of the electro-optical device.

  Further, on the TFT array substrate 10 shown in FIGS. 2 and 3, in addition to the data line driving circuit 101, the scanning line driving circuit 104 and the like, the image signal on the image signal line is sampled and supplied to the data line. Sampling circuit, precharge circuit for supplying a precharge signal of a predetermined voltage level to a plurality of data lines in advance of an image signal, for inspecting the quality, defects, etc. of the electro-optical device during production or at the time of shipment An inspection circuit or the like may be formed.

  Next, the circuit configuration and operation of the electro-optical device configured as described above will be described with reference to FIG.

  FIG. 6 shows an equivalent circuit of various elements, wirings, and the like in a plurality of pixels formed in a matrix that forms the image display area of the electro-optical device. In FIG. 6, each of the plurality of pixels formed in a matrix that forms the image display region 10 a of the electro-optical device according to the present embodiment includes a pixel electrode 9 a and a TFT 30 for switching control of the pixel electrode 9 a. The data line 6 a formed and supplied with an image signal is electrically connected to the source of the TFT 30. The image signals S1, S2,..., Sn written to the data lines 6a may be supplied line-sequentially in this order, or may be supplied for each group to a plurality of adjacent data lines 6a. Good.

  Further, the gate electrode 3a is electrically connected to the gate of the TFT 30, and the scanning signals G1, G2,..., Gm are pulse-sequentially applied in this order to the scanning line 11a and the gate electrode 3a at a predetermined timing. It is comprised so that it may apply. The pixel electrode 9a is electrically connected to the drain of the TFT 30, and the image signal S1, S2,..., Sn supplied from the data line 6a is obtained by closing the switch of the TFT 30 as a switching element for a certain period. Write at a predetermined timing.

  Image signals S1, S2,..., Sn written in a liquid crystal as an example of an electro-optical material via the pixel electrode 9a are held for a certain period with the counter electrode 21 formed on the counter substrate 20. The The liquid crystal modulates light and enables gradation display by changing the orientation and order of the molecular assembly depending on the applied voltage level. In the normally white mode, the transmittance for incident light is reduced according to the voltage applied in units of each pixel, and in the normally black mode, the light is incident according to the voltage applied in units of each pixel. The light transmittance is increased, and light having a contrast corresponding to the image signal is emitted from the electro-optical device as a whole.

  In order to prevent the image signal held here from leaking, a storage capacitor 70 is added in parallel with the liquid crystal capacitor formed between the pixel electrode 9 a and the counter electrode 21. The storage capacitor 70 is provided side by side along the scanning line 11a, and includes a capacitor electrode 300 including a fixed potential side capacitor electrode and fixed at a constant potential.

<3: Configuration of dust removal device>
Next, the overall configuration of the embodiment according to the dust removing apparatus of the present invention will be described with reference to FIGS.

  First, a configuration relating to the arrangement of the dust removing device with respect to the electro-optical device will be described with reference to FIG. FIG. 7 is a layout diagram illustrating a configuration relating to the arrangement of the dust removing device with respect to the electro-optical device.

  In this embodiment, the dust removing device is provided on both or any one of the dust-proof glass 400 provided on the counter substrate 20 side and the TFT array substrate 10 side. The dust removing device includes an elastic wave generating unit 750 and an elastic wave receiving unit 760.

  In the electro-optical device, the elastic wave generating unit 750 and the elastic wave receiving unit 760 are provided on the surface of the dust-proof glass 400 opposite to the side facing the main body 100 of the electro-optical device.

  More specifically, as shown in FIG. 7, the elastic wave generating unit 750 and the elastic wave receiving unit 760 are opposed to, for example, a peripheral region on the substrate surface of the dust-proof glass 400 via the image display region 10a. It is arranged at each position. The elastic wave generator 750 is disposed so as to overlap, for example, a region where the plurality of wirings 105 are provided on the TFT array substrate 10, and the elastic wave receiver 760 is a data line driving circuit on the TFT array substrate 10, for example. 101 is arranged so as to overlap with the provided area. By comprising in this way, the elastic wave generation part 750 and the elastic wave receiving part 760 can be provided, without changing the size of the dust-proof glass 400 or the image display area 10a.

  The detailed configurations of the elastic wave generation unit 750 and the elastic wave reception unit 760 will be described later. The elastic wave generation unit 750 and the elastic wave reception unit 760 include piezoelectric elements 700a and 700b, respectively. The piezoelectric elements 700a and 700b have the same configuration.

  Next, with reference to FIG. 8 in addition to FIG. 7, the configuration of the piezoelectric element 700a included in the elastic wave generation unit 750 will be described in detail. FIG. 8 schematically shows the structure of the dust-proof glass 400 and the piezoelectric elements 700a and 700b in the cross section taken along the line A-A 'of FIG. In FIG. 8, in order to make each member recognizable on the drawing, the scale is different for each member. In addition, regarding the configuration of the piezoelectric element 700b included in the elastic wave receiving unit 760, the description of the same configuration as that of the piezoelectric element 700a in the elastic wave generating unit 750 is omitted.

  As shown in FIGS. 7 and 8, the piezoelectric elements 700a and 700b are arranged at positions facing each other via the image display region 10a. In FIG. 8, paying attention to the configuration of the piezoelectric element 700a, the piezoelectric element 700a displays an image by a piezoelectric material such as ZnO (zinc oxide), PZT (Pb (Zr, Ti) O3), or AlN (aluminum nitride). A piezoelectric film 703 formed along one side of the region 10a, a silicon oxide (SiO 2) film 701 formed on the piezoelectric film 703, and a comb-teeth electrode, that is, an IDT (Inter-electrode) formed on the silicon oxide film 701. (Digital Transducer) 702, and a lower electrode 705 formed of a metal material containing aluminum (Al) or a transparent conductive material such as ITO (Indium Tin Oxide) so as to sandwich the IDT 702 and the piezoelectric film 703. Preferably, the thickness of each of the lower electrode 705 and the silicon oxide film 701 and the IDT 702 in the direction perpendicular to the substrate surface of the dust-proof glass 400 is extremely thin compared to the piezoelectric film 704. (For example, the piezoelectric film 703 is formed with a film thickness of 2 [μm], and the silicon oxide film 701 is formed with a film thickness of about 0.005 to 0.01 [μm].) The thickness h10 in the direction perpendicular to the substrate surface of the dustproof glass 400 is substantially the same as the piezoelectric film 703, for example, 2 [μm]. Note that the lower electrode 705 may be grounded or electrically floating. In addition, the piezoelectric film 703 and the IDT 702 may be formed of the same material in order to reduce the number of processes related to the manufacture thereof.

  FIG. 9 shows the configuration of the IDT 702 as viewed in plan on the substrate surface of the dust-proof glass 400. In FIG. 9, the scales of the respective members are made different from each other in order to make each member recognizable on the drawing. In the IDT 702, a pair of electrodes 78a and 78b formed of a metal material containing, for example, copper (Cu) or aluminum (Al), or a transparent conductive material such as ITO, is connected to the image display region 10a from the peripheral region on the piezoelectric film 703. It is formed by arranging two or more along the direction which goes to. The pair of electrodes 78a and 78b are arranged adjacent to each other at a predetermined interval, that is, a pitch. The IDT 702 is formed to extend on the piezoelectric film 703 along the arrangement direction of the pair of electrodes 78a and 78b.

  Returning to FIG. 7, in the peripheral area on the dust-proof glass 400, an electrode part 70 a for driving the IDT 702 in the piezoelectric element 700 a of the elastic wave generating part 750, an electrode part 72 a for grounding the lower electrode 705, and these Wiring 71 and the like connected to the electrode portions 70a and 70b are further provided. Similarly to the configuration on the elastic wave generating unit 750 side, the elastic wave receiving unit 760 side is also provided with an electrode unit 70b for driving the IDT 702, an electrode unit 72b for grounding, and the like.

  FIGS. 10A and 10B show a configuration relating to the connection of the flexible substrate to the electro-optical device and the dust removing device. FIG. 10B is a cross-sectional view at an arbitrary position of the main body 100 of the electro-optical device in FIG. The external circuit connection terminal 102 shown in FIG. 3 and FIG. 4 or FIG. 5 is an image signal input from the personal computer 1 to the liquid crystal projector 1100 and supplied to the electro-optical device, as well as a clock signal, various control signals, and a power source. A driving IC that supplies a signal or the like to the data line driving circuit 101 or the scanning line driving circuit 104 is TAB-mounted. More specifically, the driving IC is mounted on the main body 100 of the electro-optical device by being electrically connected to the external circuit connection terminal 102 via a plurality of wirings formed on the flexible substrate 503. Is done.

  In addition to the electrode portions 70a and 72a provided on the elastic wave generating portion 750 side and the wiring 71, the electrode portions 70b and 72b provided on the elastic wave receiving portion 760 side are formed on the flexible substrate 501. It is electrically connected to a plurality of wirings. In FIG. 10A and FIG. 10B, the detailed configuration such as the driving IC and the wiring in the flexible substrates 501 and 503 is not shown.

Next, a more detailed configuration of the dust removing device will be described with reference to FIG. FIG. 11A is a diagram illustrating an electrical configuration of the elastic wave generation unit 750, and FIG. 11B is a diagram illustrating an electrical configuration of the elastic wave reception unit 760.
In FIG. 11A, the elastic wave generator 750 is formed as a Colpitts oscillation circuit including the piezoelectric element 700a. More specifically, one electrode of the storage capacitor 752 is electrically connected to the pair of electrodes 78a and 78a in the IDT 702 of the piezoelectric element 700a. The other electrode of the storage capacitor 752 is grounded. The pair of electrodes 78a and 78b in the IDT 702 are electrically connected to the amplifier 756, respectively. Note that one of the pair of electrodes 78 a and 78 a is electrically connected to the amplifier 756 via the inverter 754. Further, in FIG. 11A, the storage capacitor 752, the inverter 754, and the amplifier 756 other than the piezoelectric element 700a are formed on the dust-proof glass 400 together with the piezoelectric element 700a in FIG. Rarely, it is electrically connected to the piezoelectric element 700 a through the plurality of wirings in the flexible substrate 501, the electrode part 70 a and the wiring 71.

  11B, in addition to the piezoelectric element 700b, the elastic receiving unit 760 outputs the AC signal output from the piezoelectric element 700b to a DC signal, and further outputs from the smoothing circuit 762. An A / D (analog-to-digital) converter 764 for digitally converting the DC signal is included. The elastic wave receiving unit 760 is electrically connected to the detection circuit 766 and the determination circuit 768, respectively.

  An antireflection film (AR coating) or the like may be formed on the surfaces of the elastic wave generating unit 750 and the elastic wave receiving unit 760 as described above, that is, on the IDT 702.

  Furthermore, in the present embodiment, a driving device 800 that is a driving unit for driving the elastic wave generating unit 750 is provided as a part of the dust removing device. With reference to FIG. 12, the structure which concerns on the drive device 800 is demonstrated. FIG. 12 is a block diagram for explaining a configuration related to driving device 800.

  In the present embodiment, the driving device 800 is attached to the electro-optical device by being electrically connected to the electrode portions 70 a and 72 a and the wiring 71 through a plurality of wirings formed on the flexible substrate 501, for example. Alternatively, at least a part of the driving device 800 may be provided in the electro-optical device together with the data line driving circuit 101 and the scanning line driving circuit 104. In the present embodiment, the driving device 800 may be attached to the electro-optical device via the flexible substrate 501 separately from the dust removing device, or at least a part of the driving device 800 may be provided in the electro-optical device. It may be.

  The driving device 800 is provided with a power-on signal generation unit 806, an operation button 804, and a timer 802 as measurement means for measuring time. The power-on signal generation unit 806 generates a power-on signal J1 in response to power-on of the electro-optical device performed in conjunction with power-on of the liquid crystal projector 1100, for example, and supplies it to the driving device 800. Further, the operation button 804 generates an operation signal J2 in response to an external operation on the operation button 804 and supplies the operation signal J2 to the driving device 800.

  The driving device 800 generates an elastic wave according to the power-on signal J1 and the operation signal J2 or, as described later, according to the detection signal F output from the detection circuit 766 or the determination circuit 768 shown in FIG. The generator 750 is driven. Alternatively, the driving device 800 drives the elastic wave generation unit 750 regularly or irregularly at a predetermined time measured by the timer 802.

<4: Operation of the dust removal device>
Next, with reference to FIGS. 13 to 18 in addition to FIGS. 1 to 12, the operation of the dust removal apparatus in the present embodiment will be described.

  First, with reference to FIG. 13 and FIG. 14, an operation related to the elastic wave generation unit 750 in the dust removing device will be described. FIG. 13A is a schematic diagram for explaining the generation of surface acoustic waves, and FIG. 13B is a schematic diagram for explaining dust removal by the surface acoustic waves. FIG. 14 is a schematic diagram schematically showing the traveling direction of the surface acoustic wave with respect to the extending direction of the IDT 702.

  When the acoustic wave generator 700a is driven by the driving device 800, a surface acoustic wave is generated in the piezoelectric film 703 by applying a predetermined electric field by the IDT 702 in the piezoelectric element 700a. At this time, according to the configuration of the IDT 702 shown in FIG. 9, the surface acoustic waves traveling in both directions indicated by the arrows X <b> 11 and X <b> 12 in FIG. 14 are generated along the extending direction of the IDT 702. 9 and 14, a surface acoustic wave having a wavelength equal to the pitch d of the electrodes 78a and 78b adjacent to each other is generated in the piezoelectric element 700a. Of the surface acoustic waves traveling in both directions, the surface acoustic waves traveling in one direction from the peripheral region to the image display region 10a along the extending direction of the IDT 702, that is, one direction indicated by the arrow X11. The dust 405 present in the image display region 10a on the substrate surface of the dustproof glass 400 is removed as follows.

  As shown in FIG. 13A, the surface acoustic wave generated in the elastic wave generator 700a is generated in the direction indicated by the arrow X11 in the image display area 10a on the substrate surface of the dust-proof glass 400, that is, from the peripheral area to the image display area. After proceeding to 10a, it proceeds in the direction from the image display area 10a toward the peripheral area. As the substrate surface of the dust-proof glass 400 vibrates due to such surface acoustic waves, the dust 405 present in the image display area 10a is converted into an arrow X21 in FIG. 13A and an arrow X22 in FIG. 13B. , For example, in a direction from the image display region 10a toward the peripheral region according to the traveling direction of the surface acoustic wave.

  Here, the thickness h10 of each of the piezoelectric elements 700a and 700b is, for example, about 2 [μm], and as shown in FIG. 13B, the size of the substantially spherical dust 405, that is, the diameter of the dust 405. R0 is, for example, about 100 [μm]. The dust 405 moved to the vicinity of the edge of the image display area 10a by the surface acoustic wave exceeds the step on the substrate surface of the dust-proof glass 400 caused by the thickness of the piezoelectric element 700a, as indicated by an arrow Y0 in FIG. Thus, the image display area 10a is removed into the peripheral area. As described above, the surface acoustic wave generated from the elastic wave generation unit 750 and traveling to the image display region 10a and reaching the elastic wave reception unit 760 on one side of the image display region 10a is received by the elastic wave reception. Received by unit 760.

  In the present embodiment, in particular, dust is removed based on the size and type of dust to be removed from the image display area 10a, ease of dropping on the substrate surface, image quality required by specifications, and the like on the substrate surface of the dust-proof glass 400. It is preferable to generate the surface acoustic wave with a strength that can be removed as much as necessary. In order to obtain such an intensity, it is preferable that the surface acoustic wave has a low frequency by widening the pitch of the electrodes 78a and 78b in the IDT 702 and increasing the wavelength. In this way, the amplitude of the surface acoustic wave is increased, so that it is possible to screen off dust from the substrate surface of the dust-proof glass 400, for example, with a relatively strong surface acoustic wave.

  For example, in the piezoelectric element 700a, surface acoustic waves having a plurality of types of frequencies corresponding to the size of dust may be generated for each value of the frequency. Thereby, in the image display region 10a of the electro-optical device, among the dusts existing on the substrate surface, dusts of a plurality of sizes can be moved and removed by the surface acoustic waves having the corresponding frequencies.

Here, in FIG. 15, in the piezoelectric element 700 a, the vertical axis represents k ² (electromechanical coupling coefficient) when the piezoelectric film 703 is formed of ZnO, and the surface acoustic wave wavelength (λ) or the piezoelectric film 703. A graph showing the value kh determined based on the film thickness (≈h10) on the horizontal axis is shown.

  The value kh on the horizontal axis is a value represented by Expression (1).

  kh = 2πh10 / λ (1)

According to the configuration of the piezoelectric element 700a in the present embodiment, the relationship between the electromechanical coupling factor k ² and a value kh is 15, indicated by the characteristic curve 204 representing a solid line.

As described above, when the frequency of the surface acoustic wave is changed, the wavelength changes, so the value of the electromechanical coupling coefficient k ² also changes. Therefore, when changing the frequency of the surface acoustic wave, it is preferable to adjust the value of the electromechanical coupling coefficient k ² in consideration of the film thickness of the piezoelectric film 703. In this way, the surface acoustic wave can be generated with a strength that can remove dust more reliably. For example, the value kh is the highest in FIG. 15 by adjusting the film thickness of the piezoelectric film 703 and the wavelength of the surface acoustic wave so as to correspond to the position of the characteristic curve 204 indicated by the arrow 204a in FIG. The strength is obtained, and the surface acoustic wave having the strength can efficiently remove the dust by efficiently using the electric power for driving the acoustic wave generation unit 750. ZnO and AlN are excellent in the ease of forming the piezoelectric film 703. In order to excite vibrations efficiently, it is preferable to use a piezoelectric film having a high coupling coefficient such as PZT or KNbO3, although the film formation is inferior to ZnO or AlN.

  In addition, in the liquid crystal projector 1100, an elastic wave generator is provided to preferentially advance the surface acoustic wave in a direction in which dust easily moves according to the layout of each of the three types of light valves 600R, 600G, and 600B. 750 may be provided.

  FIG. 16 shows an example of an arrangement relationship between the dichroic prism 1112 and the main body portion 100 of the electro-optical device arranged as one of the three types of light valves 600R, 600G, and 600B in the liquid crystal projector 1100. .

  In FIG. 16, the light emitted from the lamp unit 1102 enters the main substrate 100 of the electro-optical device from the counter substrate 20 side, exits from the TFT array substrate 10 side, and then enters the dichroic prism 1112. In FIG. 16, the cooling air flows along the substrate surface of the dust-proof glass 400 with respect to the main body 100 of the electro-optical device, in the direction of the arrow z 0 in FIG. 16, that is, the installation of the dichroic prism 1112 in the liquid crystal projector 1100. It is supplied so as to flow in a direction from the surface I toward the installation surface I.

  In this case, for example, on the substrate surface of the dust-proof glass 400, the same direction as the arrow X11b in FIG. 16, that is, the direction corresponding to gravity, or the direction indicated by the arrow X11a in FIG. The elastic wave generation unit 750 is provided along one side of the image display region 10a so that the surface acoustic wave preferentially travels in the direction of. If comprised in this way, it will become possible to perform dust removal more reliably and efficiently.

  Next, a series of operations in the dust removal apparatus related to dust removal as described above will be described with reference to FIGS. 17 and 18. Here, FIG. 17 is a diagram illustrating a flow chart for explaining a series of operations in the dust removal apparatus related to dust removal. FIG. 18 is a diagram illustrating the case where dust is present on the substrate surface of the dust-proof glass 400. It is a schematic diagram for demonstrating the progress of the surface acoustic wave on the substrate surface.

  In FIG. 17, first, when the elastic wave generating unit 750 is driven by the driving device 800 and a series of operations related to dust removal is started, a surface acoustic wave is generated from the elastic wave generating unit 750 (step). S101).

  Next, the elastic wave receiving unit 760 receives the surface acoustic wave generated by the elastic wave generating unit 750 and traveling to the image display region 10a on the substrate surface of the dust-proof glass 400 via the image display region 10a (step S102). ).

  Here, in FIG. 18, in the image display region 10 a on the substrate surface of the dust-proof glass 400, the surface acoustic wave that has traveled through the portion where the dust 405 does not exist is indicated by the elastic wave receiving unit 760. To reach. The surface acoustic wave that has reached the acoustic wave receiving unit 760 is received by the piezoelectric element 700b. More specifically, a surface acoustic wave can be received by the surface acoustic wave reaching the acoustic wave receiving unit 760 traveling to the piezoelectric film 703 of the piezoelectric element 700b and generating vibrations on the surface thereof.

  On the other hand, in the image display area 10a on the substrate surface of the dust-proof glass 400, as indicated by an arrow X11bb in the figure, the surface acoustic wave that has traveled through the portion where the dust 405 is present is blocked by the dust 405, and receives the elastic wave. Compared to the case where the part 760 does not reach the part 760 or the part where the dust 405 does not exist and reaches the part receiving the elastic wave receiver 760, the part reaches the part 760 with weak intensity.

  Thus, the surface acoustic wave received by the piezoelectric element 700b is input to the smoothing circuit 762 as an AC signal. Then, after being converted into a DC signal by the smoothing circuit 762, it is output as a digital signal from the A / D converter 764 and input to the detection circuit 766 or the determination circuit 768.

  Subsequently, the detection circuit 766 or the determination circuit 768 calculates the intensity of the surface acoustic wave received by the elastic wave receiving unit 760 based on the input digital signal (step S103).

  Subsequently, when there is no dust, the detection circuit 766 or the determination circuit 768 uses the intensity of the surface acoustic wave to be received by the elastic wave receiving unit 760 as a reference value and compares the reference value with the calculated intensity. (Step S104). As a result, when the calculated intensity is equal to or higher than the reference value (step S104: YES), the detection circuit 766 detects that no dust is present (step S105). Alternatively, or instead, the determination circuit 768 detects that no dust is present (step S105) when the calculated intensity is equal to or higher than the reference value (step S104: YES). ), It is determined that dust has been removed.

  If the intensity calculated from the reference value is lower (step S104: NO), the detection circuit 766 detects the presence of dust (step S106). Alternatively, or in addition, the determination circuit 768 detects the presence of dust (step S106) when the calculated intensity is lower than the reference value (NO in step S104), and the dust is not removed. Determine that.

  Thereafter, the detection circuit 766 or the determination circuit 768 generates a detection signal F indicating that dust is present or absent based on the detection result described above (step S107). The detection signal F generated and output by the detection circuit 766 or the determination circuit 768 is input to the driving device 800 shown in FIG.

  In accordance with the detection signal F, the driving device 800 drives the elastic wave generating unit 750 so as to increase the intensity of the surface acoustic wave when dust is present in the image display region 10a. Thus, in order to increase the intensity of the surface acoustic wave, for example, the voltage applied to the IDT 702 of the piezoelectric element 700a in the elastic wave generation unit 750 may be increased.

  Alternatively, the driving device 800 drives the elastic wave generation unit 750 according to the detection signal F so that the intensity of the surface acoustic wave is lowered when no dust is present in the image display region 10a. As described above, the case where the intensity of the surface acoustic wave is lowered includes the case where the intensity of the surface acoustic wave is lowered to “0”, that is, the driving of the acoustic wave generator 750 is stopped. In order to reduce the intensity of the surface acoustic wave, for example, the voltage applied to the IDT 702 of the piezoelectric element 700a in the acoustic wave generator 750 may be reduced.

  Therefore, dust can be reliably removed from the image display area 10a on the substrate surface of the dust-proof glass 400. In addition, when no dust is present in the image display area 10a on the substrate surface at the start of dust removal or after dust removal, the driving device 800 stops driving the elastic wave generator 750 to remove dust. It is possible not to do so.

  Therefore, according to the dust removal device of the present embodiment as described above, dust is reflected in the display image on the screen displayed by the electro-optical device which is the liquid crystal light valve 600R, 600G, 600B in the liquid crystal projector 1100. Can be prevented. Further, it is possible to prevent the polarization state of the light incident on the electro-optical device through the polarizing plate from being changed by dust existing in the light path. For this reason, it is possible to prevent light leakage when a high gradation display image is displayed on the screen. As a result, high-quality image display can be performed by the electro-optical device.

  Here, in the electro-optical device, for example, when the substrate surface of the dustproof glass 400 provided on the TFT array substrate 10 is vibrated by the same bulk vibration as in the prior art, not only the dustproof glass 400 but also the TFT array substrate 10 is vibrated by the vibration. By bending, for example, a crack may occur in the semiconductor layer of the TFT 30. On the other hand, in the dust removal apparatus of the present embodiment, the substrate surface is vibrated by the surface acoustic wave, so that the substrate can be prevented from being bent and dust can be removed without damaging the laminated structure. Become.

  In this embodiment, dust attached to the substrate surface can be removed by the dust removing device, so that the main body 100 of the electro-optical device is not provided with the dustproof glass 400, the defocus glass, the cover glass, or the like. It may be. In this case, the dust removing device is provided for both or one of the counter substrate 20 and the TFT array substrate 10. With this configuration, the electro-optical device can be reduced in thickness or size, and the space for providing the light valves 600R, 600G, and 600B in the liquid crystal projector 1100 can be reduced.

  In the present embodiment, the elastic wave generation unit 750 is formed in the peripheral region on the dust-proof glass 400 along one side of the image display region 10a. However, the elastic wave generation unit 750 has an adjacent image display. You may make it provide along 2 sides or 3 sides of the area | region 10a. The elastic wave receiving unit 760 may be configured to generate a surface acoustic wave as described later, or an elastic wave generating unit 750 may be provided instead of the elastic wave receiving unit 760. In this case, by driving the elastic wave generators 750 provided along two or more sides of the image display area 10a, dust existing in the image display area 10a is removed from the image display area 10a by the surface acoustic waves. It can be removed by moving in two or more directions toward the region. Alternatively, a surface acoustic wave is generated by selectively driving any one of the elastic wave generators 750 provided along two or more sides of the image display area 10a, and the peripheral area is generated from the image display area 10a. It is also possible to remove the trash by moving it in one direction toward.

<5;Modification>
A modification of the present embodiment described above will be described with reference to FIGS.

FIG. 19 shows a configuration of a portion corresponding to the cross section shown in FIG. 8 for a modified example related to the configuration of the piezoelectric element 700a or 700b. 9 schematically shows the structure of the dust-proof glass 400 and the piezoelectric elements 700a and 700b, as in FIG. The lower electrode 705 may not be provided in the piezoelectric element 700a or 700b. In such a configuration, the relationship between the electromechanical coupling factor k ² and a value kh is 15, indicated by the characteristic curve 202 represented by dotted lines. When the characteristic curve 202 is compared with the characteristic curve 204 and the lower electrode 705 is not provided, if the film thickness (≈h10) of the piezoelectric film 703 is relatively large, a surface acoustic wave is generated with higher strength. Thus, it is possible to efficiently remove dust.

  Further, in the piezoelectric element 700a or 700b, the IDT 702 is configured as shown in FIGS. 20 to 22, and is indicated by an arrow X11 in one direction from the peripheral region to the image display region 10a along the extending direction of the IDT 702. A surface acoustic wave that preferentially travels in one direction may be generated. In this way, the surface acoustic wave generated in the piezoelectric element 700a can be used for dust removal without waste.

  20, FIG. 21 (a), and FIG. 22 show the configuration of the IDT 702 in the present modification, as in FIG. FIG. 21B is a cross-sectional view showing the positional relationship between the IDT 702, the silicon oxide film 701, and the piezoelectric film 703 in the B-B ′ portion of FIG.

  As shown in FIG. 20, in addition to the pair of electrodes 78a and 78b, the IDT 702 includes an electrode 78c disposed between the pair of electrodes 78a and 78b to add mass to the pair of electrodes 78a and 78b. Including.

  Alternatively, as shown in FIGS. 21A and 21B, a pair of electrodes 78a and 78b are formed on the piezoelectric film 703, and the pair of electrodes 78a and 78b are embedded to form a silicon oxide film on the piezoelectric film 703. 701 is formed. Further, an electrode 78d is formed on the silicon oxide film 701 and disposed between the pair of electrodes 78a and 78b in plan view.

  The electrodes 78c shown in FIG. 20 are preferably arranged at a predetermined pitch with each of the pair of electrodes 78a and 78b. In this case, the IDT 702 is formed by arranging a pair of electrodes 78a and 78b and an electrode 78c at a predetermined pitch along the extending direction. In addition, the electrode 78d shown in FIGS. 21A and 21B is also preferably arranged in the same manner as the electrode 78c shown in FIG.

  Further, as shown in FIG. 22A, the IDT 702 includes a floating electrode 78e disposed between the pair of electrodes 78a and 78b in addition to the pair of electrodes 78a and 78b. The floating electrode 78e is arranged at a position shifted from the approximate center between the pair of electrodes 78a and 78b arranged in the extending direction of the IDT 702 at a predetermined pitch in a plan view.

  In addition, as shown in FIG. 22B, the IDT 702 includes two types of electrodes 78f and 78g having different widths in the extending direction of the IDT 702 in plan view, and the two types of electrodes 78f and 78g. One electrode and an electrode 78h formed with the same width in the extending direction of the IDT 702 are included. A floating electrode 78i is arranged between the two types of electrodes 78f and 78g. These four types of electrodes 78f, 78g, 78h, and 78i are arranged at a predetermined pitch.

  FIG. 23 is a block diagram showing a configuration according to a modification of the elastic wave generating unit 750 or the elastic wave receiving unit 760.

  In the acoustic wave receiving unit 760, a Colpitts type transmission circuit as described with reference to FIG. 11A, for example, including the piezoelectric element 700b is formed so that a surface acoustic wave can be generated in the piezoelectric element 700b. The That is, in this case, the elastic wave generator 750 is also formed in the elastic wave receiver 760. A switching circuit 759 is preferably provided to switch the operation of the elastic wave receiving unit 760 and the elastic wave generating unit 750 sharing the piezoelectric element 700b. For example, when the first switching signal Sc1 is supplied to the liquid crystal projector 1100 by an external operation of an input device such as a keyboard in the personal computer 1, the first switching signal Sc1 is input to the switching circuit 759. Then, the switching circuit 759 enables the elastic wave generation unit 750 to operate in response to the first switching signal Sc1.

  Alternatively, in the elastic wave generating unit 750, the elastic wave receiving unit 760 including the piezoelectric element 700a and described with reference to FIG. 11B is provided so that the piezoelectric element 700a can receive the surface acoustic wave. The elastic wave generator 750 may be formed. In this case, similarly to the case where the elastic wave generating unit 750 is formed in the elastic wave receiving unit 760, the switching circuit is used to switch the operations of the elastic wave receiving unit 760 and the elastic wave generating unit 750 that share the piezoelectric element 700a. 759 is preferably provided. Then, the switching circuit 759 enables the elastic wave receiving unit 760 to operate according to the second switching signal Sc2 that is input in the same manner as the first switching signal Sc1. Also in this case, the detection circuit 766 or the determination circuit 768 detects the presence of dust based on the intensity of the surface acoustic wave received by the elastic wave receiving unit 760 formed in the elastic wave generating unit 750, and The detection signal F may be generated.

  In addition, the elastic wave generation unit 750 is provided with a device for monitoring how much the surface acoustic wave is easily generated from the elastic wave generation unit 750 on the surface of the substrate or how much the surface acoustic wave travels, or By providing a device for monitoring how much power is consumed in the elastic wave generating unit 750 to generate a surface acoustic wave having the same amplitude, the presence of dust on the surface of the surface acoustic wave is prevented. You may comprise so that it may detect.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification, and dust removal accompanying such a change is possible. An apparatus and a dust removal method, an electro-optical device including the dust-removing device, and an electronic apparatus including the electro-optical device are also included in the technical scope of the present invention.

It is a figure which shows the actual structure in the case of the image display by a liquid crystal projector. It is a schematic sectional view showing a configuration example of a liquid crystal projector. FIG. 3 is a plan view of the electro-optical device when the TFT array substrate is viewed from the side of the counter substrate together with each component formed thereon. It is H-H 'sectional drawing of FIG. 1 is a perspective view schematically showing a configuration of an electro-optical device provided with dustproof glass. It is a figure which shows equivalent circuits, such as various elements and wiring in a some pixel of an electro-optical apparatus. FIG. 6 is a layout diagram illustrating a configuration related to the arrangement of the dust removing device with respect to the electro-optical device. FIG. 8 is a diagram schematically illustrating a configuration of dust-proof glass and a piezoelectric element in a cross section taken along line A-A ′ of FIG. 7. It is a figure which shows the structure of IDT seen planarly on the board | substrate surface of dustproof glass. FIGS. 10A and 10B are diagrams illustrating a configuration relating to connection of the flexible substrate to the electro-optical device and the dust removing device. Fig.11 (a) is a figure which shows the electrical structure of an elastic wave generation part, FIG.11 (b) is a figure which shows the electrical structure of an elastic wave receiving part. It is a block diagram for demonstrating the structure which concerns on a drive device. FIG. 13A is a schematic diagram for explaining the generation of surface acoustic waves, and FIG. 13B is a schematic diagram for explaining dust removal by the surface acoustic waves. It is a schematic diagram which shows typically the advancing direction of the surface acoustic wave with respect to the extension direction of IDT. k 2 a ^{(electromechanical} coupling coefficient) placed vertically, is a diagram showing a graph representing the value kh abscissa. FIG. 4 is a diagram illustrating an example of an arrangement relationship between a main body portion of an electro-optical device and a dichroic prism in a liquid crystal projector. It is a figure which shows the flowchart for demonstrating a series of operation | movement in the dust removal apparatus which concerns on dust removal. It is a schematic diagram for explaining the progress of surface acoustic waves on the substrate surface when dust is present on the substrate surface of the dust-proof glass. It is a figure which shows the structure of the part corresponding to the cross section shown in FIG. 8 about the modification which concerns on a structure of a piezoelectric element. Like FIG. 9, it is a figure which shows an example of a structure of IDT in this modification. FIG. 21A is a diagram illustrating another example of the configuration of the IDT in the present modified example, as in FIG. 9, and FIG. It is sectional drawing shown about the arrangement | positioning relationship of IDT, a silicon oxide film, and a piezoelectric film. FIG. 22A and FIG. 22B are diagrams showing other examples of the configuration of the IDT in the present modification, as in FIG. It is a block diagram which shows the structure which concerns on the modification of an elastic wave generation part or an elastic wave receiving part.

Explanation of symbols

70a, 70b, 72a, 72b ... electrode part, 71 ... wiring, 400 ... dustproof glass, 750 ... elastic wave generating part

Claims (14)

An electro-optical device that has a substrate and displays an image electro-optically in an image display area on the substrate, the dust removing device for an electro-optical device for removing dust on the surface of the substrate,
An acoustic wave generator for generating a surface acoustic wave that travels along the surface of the substrate in the image display region;
A dust removing device for an electro-optical device, comprising: a wiring or an electrode portion for driving the elastic wave generating portion.   The elastic wave generating unit is disposed in a peripheral region located around the image display region on the substrate, and generates the surface acoustic wave so as to travel from the peripheral region to the image display region. The dust removing apparatus for an electro-optical device according to claim 1, wherein   The dust removal apparatus for an electro-optical device according to claim 2, wherein the elastic wave generation unit is provided along one side of the image display area.   The dust removing apparatus for an electro-optical device according to claim 2, wherein the elastic wave generating unit is provided along two sides of the image display area.   The elastic wave generating unit includes a piezoelectric film formed along at least one side of the image display area, and at least two electrodes arranged on the piezoelectric film along a direction from the peripheral area toward the image display area. And a piezoelectric element that generates the surface acoustic wave that travels along the extending direction of the comb-tooth electrode, and includes comb-shaped electrodes that are formed to extend along the arrangement direction. The dust removing apparatus for an electro-optical device according to any one of claims 2 to 4, wherein   The said piezoelectric element produces | generates the said surface acoustic wave which advances preferentially in one direction which goes to the said image display area | region from the said peripheral area along the extension direction of the said comb-tooth electrode. The dust removal apparatus for electro-optical devices as described. The dust removal apparatus for an electro-optical device according to claim 5, wherein the piezoelectric element generates the surface acoustic wave having a predetermined frequency capable of removing the dust. The dust for an electro-optical device according to claim 5, wherein the piezoelectric element generates the surface acoustic waves having a plurality of types of frequencies corresponding to the size of the dust for each value of the frequency. Removal device. The substrate is provided in the main body of the electro-optical device as defocus glass, cover glass or dust-proof glass,
8. The dust removing apparatus for an electro-optical device according to claim 1, wherein the dust is removed on a surface of the substrate opposite to the side facing the main body. 9. The substrate is provided in the main body of the electro-optical device as one of a pair of substrates sandwiching an electro-optical material,
8. The dust removing apparatus for an electro-optical device according to claim 1, wherein the dust is removed on a surface of the one substrate opposite to the side facing the electro-optical material. 9. .   An electro-optical device comprising the dust removing device for an electro-optical device according to claim 1.   An electronic apparatus comprising the electro-optical device according to claim 11. A dust removal device for removing dust on the surface of a substrate,
An elastic wave generator for generating a surface acoustic wave that travels along the surface of the substrate;
A dust removal apparatus comprising: a wiring or an electrode portion for driving the elastic wave generating means. An electro-optical device that has a substrate and displays an image electro-optically in an image display area on the substrate, wherein the dust is removed from the surface of the substrate.
Driving a surface acoustic wave generating unit that generates a surface acoustic wave that travels along the surface of the substrate in the image display region via a wiring or an electrode; and
And a step of generating the surface acoustic wave by the driven elastic wave generator.

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