JP2011221097A - Substrate for electrophoretic display device, electrophoretic display device and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate for an electrophoretic display device which can reliably suppress the occurrence of display unevenness and consumes less energy by providing a storage capacitor having a sufficient capacitance value.SOLUTION: In a substrate 30 for an electrophoretic display device of the present invention, first and second TFTs 72, 73 include gate electrodes 74, 75 made of a first conductive film, a gate insulating film 83 made of a first insulating film, a semiconductor layer 76, and a source electrode 77 and a drain electrode 79 made of a second conductive film. A first storage capacitor 71A is composed of a first storage-capacitor electrode 80A made of a light-blocking metal film, a second passivation film 85B and a pixel electrode 35. At least a part of the first storage-capacitor electrode 80A overlaps with the first and second TFTs 72, 73 and at least a part of a wiring such as a data line 68 and a scan line.

Description

  The present invention relates to an electrophoretic display device substrate, an electrophoretic display device, and an electronic apparatus.

  2. Description of the Related Art As an electrophoretic display device which is a kind of electro-optical device, a configuration in which an electrophoretic element having a liquid phase dispersion medium and electrophoretic particles is sandwiched between a pair of substrates is known. Since this type of electrophoretic display device has a memory property, it is not always necessary to apply a voltage in order to maintain the display state, and it is sufficient if a voltage can be applied only for a period required to change the display state. However, the voltage must be held for a certain period in each pixel constituting the display, and each pixel needs to have a storage capacitor. Therefore, an electrophoretic display device having a storage capacity is disclosed in Patent Documents 1 and 2 listed below. According to Patent Documents 1 and 2, in these devices, the pixel voltage is sufficiently maintained by adding a storage capacitor in parallel with the electrophoretic element capacitor formed between the pixel electrode and the common electrode. It can be done.

Japanese Patent No. 4275671 JP 2005-346090 A

  The storage capacitors in the devices disclosed in Patent Documents 1 and 2 are the capacitor upper electrode formed in the same layer as the scanning line, the gate insulating film, and the capacitor upper portion formed in the same layer as the data line across the gate insulating film. And an electrode. When this configuration is adopted, since the scanning line and the capacitor lower electrode are arranged in the same layer, it is necessary to prevent a short circuit therebetween. However, in particular, when trying to increase the definition of pixels, the pixels cannot be enlarged unnecessarily. Therefore, if a large space for preventing a short circuit is provided, a storage capacitor having a sufficient capacitance value cannot be formed. Conversely, if the scanning line and the capacitor lower electrode are arranged with sufficient space to obtain a sufficient capacitance value, it is not possible to achieve high definition of the pixels.

  As other methods, there are attempts to increase the storage capacitance value by using a material having a high relative dielectric constant for the capacitor insulating film or by reducing the thickness of the capacitor insulating film. However, in these methods, since the capacitive insulating film is composed of a gate insulating film, the TFT characteristics are adversely affected, such as an increase in leakage current of a thin film transistor (hereinafter abbreviated as TFT). There is a risk.

  In addition, if the storage capacitance value is not sufficient, the feedthrough voltage when the TFT is turned off increases, and the variation in the feedthrough voltage due to the variation in the TFT capacitance becomes unacceptable. As a result, display unevenness particularly appears in the halftone display. This display unevenness is a problem peculiar to an electrophoretic display device which is a direct current display element, and is caused by a larger variation in feedthrough voltage than a liquid crystal display device having an effective value response.

  Further, if the storage capacity value is not sufficient, it is necessary to write the storage capacity over a plurality of frames in order to refresh the pixel voltage. However, the energy consumed in the electrophoretic display device (power x time) is mostly consumed for charging the parasitic capacitance of the data line, so that energy for charging the data line in the case of multiple frame driving. May be consumed wastefully, and there is a problem that power consumption increases.

  For example, in the device described in Patent Document 2, the gate insulating film, which is a capacitive insulating film, is thinned by etching. However, in this case, since the etching variation is added in addition to the gate insulating film deposition variation, the uniformity of the storage capacitance is lowered, and the problem of display unevenness due to the above-described variation in the feedthrough voltage occurs.

  In addition, the electrophoretic display device may not include a color filter and may not provide a black matrix (a lattice-shaped light shielding film between pixels) on the counter substrate on the viewing side. Alternatively, even if a color filter is provided, a black matrix may not be provided for the purpose of obtaining brightness (reflectance). In this case, since there is no black matrix, there is a possibility that external light incident from the counter substrate side is irradiated onto the TFT and the wiring. At this time, for example, when the TFT is irradiated with external light, the TFT characteristics may be adversely affected, such as an increase in TFT leakage current.

  The present invention has been made to solve the above-described problems, and by providing a storage capacitor having a sufficient capacity value, occurrence of display unevenness can be reliably suppressed, energy consumption can be reduced, and external power can be reduced. It is an object of the present invention to provide a substrate used in an electrophoretic display device with little deterioration in electrical characteristics due to light irradiation, and an electrophoretic display device. It is another object of the present invention to provide an electronic device provided with a display portion without display unevenness.

In order to achieve the above object, an electrophoretic display device substrate according to the present invention includes a substrate body, a plurality of data lines and a plurality of scanning lines provided on the substrate body, the data lines, and the data lines. A plurality of pixels partitioned by scanning lines, and each of the plurality of pixels is a substrate for an electrophoretic display device including a pixel switching element, a pixel electrode, and a first storage capacitor, wherein the pixels A switching element has a gate electrode made of a first conductive film formed on the substrate body, a gate insulating film made of a first insulating film formed so as to cover at least the gate electrode, and on the gate insulating film A semiconductor layer formed; a source electrode made of a second conductive film electrically connected to the source region of the semiconductor layer and the data line; a drain region of the semiconductor layer; and the pixel electrode. A first storage capacitor electrode made of a light-shielding metal film formed on the upper layer side of the second conductive film. A first storage capacitor insulating film made of a second insulating film formed so as to cover at least the first storage capacitor electrode, and the first storage capacitor insulating film when viewed from the normal direction of the substrate body The pixel electrode formed so that at least a part thereof overlaps the first storage capacitor electrode, and the first storage capacitor electrode when viewed from the normal direction of the substrate body Is formed so as to overlap at least part of the pixel switching element and the wiring.
The “light-shielding metal film” in the present invention refers to a film made of a known metal material excluding a transparent conductive material, and includes a film whose light transmittance is not necessarily 0% although it varies depending on the film thickness. .

  In the electrophoretic display device substrate of the present invention, the first storage capacitor includes a first storage capacitor electrode made of a light-shielding metal film formed above the second conductive film, and a first storage capacitor made of a second insulating film. The capacitor insulating film and a part of the pixel electrode formed so as to at least partially overlap the first storage capacitor electrode. That is, the first storage capacitor in the present invention does not use a capacitor electrode or a gate insulating film formed in the same layer as the scanning line as described in the conventional patent documents 1 and 2, and is higher than these layers. It is configured using the side film.

  With this configuration, by appropriately setting the film thickness and relative dielectric constant of the first storage capacitor insulating film (second insulating film), the characteristics of the first storage capacitor are designed independently of the characteristics of the pixel switching element. be able to. That is, a storage capacitor having a sufficient capacitance value can be formed without being restricted by the characteristics of the pixel switching element. In addition, since the pixel potential in a period necessary for changing the display state can be reliably held, it is not necessary to write the storage capacitor a plurality of times, and energy consumption can be greatly reduced.

  According to the configuration of the present invention, the first storage capacitor electrode positioned on the upper layer side of the second conductive film is formed of a light-shielding metal film, and at least a part of the first storage capacitor electrode is a pixel switching element. And at least part of the wiring. That is, at least a part of the pixel switching element and the wiring is covered with at least a part of the first storage capacitor electrode made of the light-shielding metal film. With this configuration, at least a part of the pixel switching element and the wiring is shielded by the first storage capacitor electrode and is electrically shielded. Therefore, leakage current, potential fluctuation, and the like of the TFT constituting the pixel switching element can be suppressed, and deterioration of TFT characteristics can be prevented.

In the electrophoretic display device substrate of the present invention, each of the plurality of pixels has a second accumulation formed such that at least a portion thereof overlaps the first accumulation capacitor when viewed from the normal direction of the substrate body. A second storage capacitor comprising a capacitor, wherein the second storage capacitor comprises a second storage capacitor lower electrode made of the first conductive film and at least a first insulating film formed to cover at least the second storage capacitor lower electrode. The storage capacitor insulating film and the second storage capacitor lower electrode are formed so that at least a portion thereof overlaps the second storage capacitor lower electrode with the second storage capacitor insulating film interposed therebetween when viewed from the normal direction of the substrate body. And 1 storage capacitor upper electrode.
According to this configuration, since the second storage capacitor is formed so that at least a part thereof overlaps the first storage capacitor when viewed from the normal direction of the substrate body, the first storage capacitor and the second storage capacitor are provided. By adding the capacity, the capacity value per unit area increases, and a sufficient storage capacity value can be obtained without increasing the occupied area.

In the electrophoretic display device substrate of the present invention, the area of the first storage capacitor formed by the overlapping portion of the first storage capacitor electrode and the pixel electrode is such that the second storage capacitor lower electrode and the second storage capacitor upper portion. It is desirable that the area is larger than the area of the second storage capacitor formed by the overlapping portion with the electrode.
According to this configuration, the area of the first storage capacitor that can have a larger capacitance value by reducing the capacitance insulating film is larger, so that the overall storage capacitance value can be further increased, and the light shielding performance and electrical shielding performance can be further improved. Can be increased.

In the electrophoretic display device substrate of the present invention, it is preferable that the thickness of the second insulating film is smaller than the thickness of the first insulating film.
According to this configuration, since the thickness of the gate insulating film made of the first insulating film can be relatively increased, leakage current of the TFT constituting the pixel switching element can be prevented and TFT characteristics can be improved. Further, since the film thickness of the first storage capacitor insulating film made of the second insulating film can be relatively reduced, the storage capacitor can be increased.

In the electrophoretic display device substrate of the present invention, a configuration in which the first storage capacitor electrode is formed over the whole of the plurality of pixels can be employed.
According to this configuration, almost all of the pixels including the space between the rows of pixels are covered with the first storage capacitor electrode, so that the light shielding performance and the electrical shielding performance can be further improved.

Alternatively, in the electrophoretic display device substrate of the present invention, it is possible to adopt a configuration in which the first storage capacitor electrode is divided and formed for each row of the plurality of pixels arranged in a matrix.
Since a common potential is applied to the first storage capacitor electrode, according to this configuration, it is possible to perform driving that changes the potential of the first storage capacitor electrode (capacitor line) for each row of a plurality of pixels. Become.

In the substrate for electrophoretic display devices of the present invention, any of non-single-crystal silicon, an oxide semiconductor material, a transparent oxide semiconductor material, and an organic semiconductor material can be used as the semiconductor layer.
According to this configuration, a TFT having excellent electrical characteristics can be manufactured relatively easily using an existing manufacturing process.

An electrophoretic device of the present invention includes a pair of substrates and an electrophoretic element sandwiched between the pair of substrates, and one of the pair of substrates is the electrophoretic display of the present invention. It is a device substrate.
According to this configuration, since the electrophoretic display device substrate of the present invention is used as one of the pair of substrates, an electrophoretic display device that suppresses variations in feedthrough voltage and has less display unevenness. realizable.

An electronic apparatus according to the present invention includes the electrophoretic display device according to the present invention.
According to the present invention, since the electrophoretic display device of the present invention is provided, an electronic apparatus including an electrophoretic display unit with little display unevenness can be realized.

1 is an equivalent circuit diagram illustrating an electrophoretic display device according to a first embodiment of the present invention. 2 is an equivalent circuit diagram of each pixel in the electrophoretic display device. FIG. 2A is a cross-sectional view of an electrophoretic display device, FIG. 2B is a cross-sectional view of a microcapsule, and FIG. 2C is a view for explaining an operation of the electrophoretic element. 2 is a plan view showing the overall configuration of the electrophoretic display device. FIG. It is a figure which shows the planar pattern of each pixel of the element substrate of an electrophoretic display device similarly. It is sectional drawing which follows the A-A 'line of FIG. It is a figure for demonstrating (a), (b) feedthrough voltage. It is a figure which shows a common electric potential. It is a figure which shows the planar pattern of each pixel of the element substrate of the electrophoretic display device of 2nd Embodiment of this invention. 2 is an equivalent circuit diagram of each pixel in the electrophoretic display device. FIG. It is a figure which shows the planar pattern of each pixel of the element substrate of the electrophoretic display device of 3rd Embodiment of this invention. It is sectional drawing which follows the A-A 'line | wire of FIG. 2 is an equivalent circuit diagram of each pixel in the electrophoretic display device. FIG. It is sectional drawing of each pixel of the element substrate in the electrophoretic display device of 4th Embodiment of this invention. It is a figure which shows one Embodiment of the electronic device of this invention. It is a figure which shows other embodiment of the electronic device of this invention. It is a figure which shows other embodiment of the electronic device of this invention.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
The electro-optical device of this embodiment is an example of an active matrix type electrophoretic display device.
FIG. 1 is an equivalent circuit diagram showing an electrophoretic display device of this embodiment. FIG. 2 is an equivalent circuit diagram of each pixel of the electrophoretic display device. 3A is a cross-sectional view of the electrophoretic display device, FIG. 3B is a cross-sectional view of the microcapsule, and FIG. 3C is a view for explaining the operation of the electrophoretic element. FIG. 4 is a plan view showing the overall configuration of the electrophoretic display device. FIG. 5 is a diagram showing a planar pattern of each pixel of the element substrate of the electrophoretic display device. 6 is a cross-sectional view taken along the line AA ′ of FIG. FIG. 7 is a diagram showing the feedthrough voltage. FIG. 8 is a diagram showing a common potential.
In the following drawings, in order to make each component easy to see, the scale of the size may be varied depending on the component.

  As shown in FIG. 1, the electrophoretic display device 100 of the present embodiment includes a display unit 5 in which a plurality of pixels 40 are arranged in a matrix. Around the display unit 5, a scanning line driving circuit 61, a data line driving circuit 62, a controller (control unit) 63, and a capacitor line driving circuit 64 are arranged. The scanning line driving circuit 61, the data line driving circuit 62, and the capacitor line driving circuit 64 are each connected to the controller 63. The controller 63 comprehensively controls these based on image data and synchronization signals supplied from the host device.

  In the display unit 5, a plurality of scanning lines 66 extending from the scanning line driving circuit 61 and a plurality of data lines 68 extending from the data line driving circuit 62 are formed, and the pixels 40 correspond to these intersecting positions. Is provided. Further, a capacitor line 67 extending from the capacitor line driving circuit 64 is provided, and the scanning line 66, the data line 68, and the capacitor line 67 are connected to the pixel 40, respectively. In the present embodiment, the capacitor line 67 is described in the equivalent circuit diagram, but the substance has a first capacitor line and a second capacitor line. The first capacitor line and the second capacitor line are They are electrically connected, and the same potential is applied to these capacitor lines. As will be described later, the substance of the first capacitor line is a first storage capacitor electrode formed over a plurality of pixels. Therefore, in FIG. 1, the first capacitor line and the second capacitor line are represented by one capacitor line.

  The scanning line driving circuit 61 is connected to each pixel 40 via m scanning lines 66 (Y1, Y2,..., Ym). Under the control of the controller 63, the first to mth rows are connected. A selection signal defining the timing at which the scanning lines 66 up to the eyes are sequentially selected and a selection transistor 41 (pixel switching element, see FIG. 2) provided in the pixel 40 is turned on is selected via the selected scanning line 66. Supply. The data line driving circuit 62 is connected to each pixel 40 via n data lines 68 (X1, X2,..., Xn), and corresponds to each pixel 40 under the control of the controller 63. An image signal defining pixel data to be supplied is supplied to the pixel 40. The capacitor line driving circuit 64 supplies a predetermined potential to the capacitor line 67 under the control of the controller 63.

  As shown in FIG. 2, each pixel 40 is provided with a selection transistor 41, a first storage capacitor 71A, a second storage capacitor 71B, a pixel electrode 35, an electrophoretic element 32, and a common electrode 37. It has been. As the pixel circuit of the present embodiment, a so-called 1T1C (1Transistor, 1Capacitor) type pixel circuit is employed, which includes one transistor and one storage capacitor. A double gate type transistor in which TFTs are connected in series is used. With this configuration, the voltage applied to the selection transistor is distributed by the two TFTs, and a sufficient breakdown voltage of each TFT can be secured.

As described above, to each pixel 40, the scanning line 66, the data line 68, the first capacitance line 67A, and the second capacitance line 67B are connected. The gate of the first TFT 72 and the gate of the second TFT 73 constituting the selection transistor 41 are connected to the scanning line 66, the source of the first TFT 72 is connected to the data line 68, and the drain of the first TFT 72 and the source of the second TFT 73 are connected to each other. The drain of the second TFT 73 is connected to the pixel electrode 35, one electrode of the first storage capacitor 71A, and one electrode of the second storage capacitor 71B. The other electrode of the first storage capacitor 71A is connected to the first capacitor line 67A, and the other electrode of the second storage capacitor 71B is connected to the second capacitor line 67B.
In the description of this embodiment, of the sources and drains of the TFTs 72 and 73, the side connected to the data line 68 (side close to the data line 68) is the source and the side connected to the pixel electrode 35 (pixel electrode) The side close to 35) is called a drain, but this is simply determined in this way for convenience, and the names of the sources and drains of the TFTs 72 and 73 may be reversed.

  In the case of this embodiment, it is assumed that an n-channel transistor is used as the selection transistor 41, but it may be replaced with another type of switching element having a function equivalent to that of the n-channel transistor. For example, a p-channel transistor may be used instead of an n-channel transistor, and an inverter or a transmission gate may be used.

  In each pixel 40, when the selection transistor 41 is turned on by a selection signal input via the scanning line 66, an image signal is input from the data line 68 to the pixel electrode 35 via the selection transistor 41, and the first The storage capacitor 71A and the second storage capacitor 71B are charged. The pixel electrode 35 is held at a predetermined potential level by the energy stored in the first storage capacitor 71A and the second storage capacitor 71B, and the electrophoretic element 32 is driven by the potential difference between the pixel electrode 35 and the common electrode 37. .

  As shown in FIG. 3A, the electrophoretic display device 100 includes a configuration in which an electrophoretic element 32 in which a plurality of microcapsules 20 are arranged is sandwiched between an element substrate 30 and a counter substrate 31. Yes. In the display unit 5, the circuit layer 34 on which the scanning lines 66, the data lines 68, the selection transistors 41, and the like illustrated in FIGS. 1 and 2 are formed is provided on the electrophoretic element 32 side of the element substrate 30. A plurality of pixel electrodes 35 are arranged on the circuit layer 34. In FIG. 3A, illustration of specific components inside the circuit layer 34 is omitted.

  The element substrate 30 (electro-optical device substrate) is a substrate made of glass, plastic, or the like, and is disposed on the side opposite to the image display surface, and thus may not be transparent. The pixel electrode 35 is formed of a transparent conductive material such as ITO (indium tin oxide) or a metal material such as Al, and applies a voltage to the electrophoretic element 32 between the pixel electrode 35 and the common electrode 37. Electrode.

On the other hand, a planar common electrode 37 facing the plurality of pixel electrodes 35 is formed on the electrophoretic element 32 side of the counter substrate 31, and the electrophoretic element 32 is provided on the common electrode 37. The counter substrate 31 is a substrate made of glass, plastic, or the like, and is disposed on the image display side. Therefore, a transparent substrate is used. The common electrode 37 is an electrode for applying a voltage to the electrophoretic element 32 together with the pixel electrode 35, and is a transparent electrode formed of MgAg (magnesium silver), ITO, IZO (indium / zinc oxide) or the like.
The electrophoretic element 32 and the pixel electrode 35 are bonded via the adhesive layer 33, so that the element substrate 30 and the counter substrate 31 are bonded.

  The electrophoretic element 32 is generally formed in advance on the counter substrate 31 side and is handled as an electrophoretic sheet including the adhesive layer 33. In the manufacturing process, the electrophoretic sheet is handled in a state where a protective release sheet is attached to the surface of the adhesive layer 33. And the display part 5 is formed by sticking the said electrophoretic sheet which peeled the release sheet with respect to the element board | substrate 30 (The pixel electrode 35, various circuits, etc.) which were manufactured separately. For this reason, the adhesive layer 33 exists only on the pixel electrode 35 side.

  As shown in FIG. 3B, the microcapsule 20 has a particle size of, for example, about 50 μm, and includes a dispersion medium 21, a plurality of white particles (electrophoretic particles) 27, and a plurality of black particles. (Electrophoretic particles) 26 are encapsulated spherical bodies. As shown in FIG. 3A, the microcapsule 20 is sandwiched between the common electrode 37 and the pixel electrode 35, and one or a plurality of microcapsules 20 are arranged in one pixel 40.

The outer shell portion (wall film) of the microcapsule 20 is formed using a translucent polymer resin such as an acrylic resin such as polymethyl methacrylate or polyethyl methacrylate, a urea resin, or gum arabic. .
The dispersion medium 21 is a liquid that disperses the white particles 27 and the black particles 26 in the microcapsules 20.

  Examples of the dispersion medium 21 include water, alcohol solvents (methanol, ethanol, isopropanol, butanol, octanol, methyl cellosolve, etc.), esters (ethyl acetate, butyl acetate, etc.), ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.). ), Aliphatic hydrocarbons (pentane, hexane, octane, etc.), alicyclic hydrocarbons (cyclohexane, methylcyclohexane, etc.), aromatic hydrocarbons (benzene, toluene, benzenes having a long-chain alkyl group ( Xylene, hexylbenzene, hebutylbenzene, octylbenzene, nonylbenzene, decylbenzene, undecylbenzene, dodecylbenzene, tridecylbenzene, tetradecylbenzene)), halogenated hydrocarbons (methylene chloride, chloroform, tetrachloride) Element, and 1,2-dichloroethane), can be exemplified a carboxylate, it may be other oils. These substances can be used alone or as a mixture, and a surfactant or the like may be further blended.

  The white particles 27 are particles (polymer or colloid) made of a white pigment such as titanium dioxide, zinc white, and antimony trioxide, and are used, for example, by being negatively charged. The black particles 26 are particles (polymer or colloid) made of a black pigment such as aniline black or carbon black, and are used by being charged positively, for example.

If necessary, these pigments include electrolytes, surfactants, metal soaps, resins, rubbers, oils, varnishes, compound charge control agents, titanium-based coupling agents, aluminum-based coupling agents, A dispersant such as a silane coupling agent, a lubricant, a stabilizer, and the like can be added.
Further, instead of the black particles 26 and the white particles 27, for example, pigments such as red, green, blue, yellow, cyan, and magenta may be used. According to such a configuration, red, green, blue, yellow, cyan, magenta, and the like can be displayed on the display unit 5.

  In the electrophoretic element 32 configured as described above, when the pixel 40 is displayed in black, as shown in FIG. 3C, the common electrode 37 is held at a relatively low potential and the pixel electrode 35 is held at a relatively high potential. . That is, when the potential of the common electrode 37 is set as a reference potential, the pixel electrode 35 is held positive. As a result, the positively charged black particles 26 are attracted to the common electrode 37, while the negatively charged white particles 27 are attracted to the pixel electrode 35. As a result, when this pixel is viewed from the common electrode 37 side, black is visually recognized. On the other hand, when the pixel 40 is displayed in white, the common electrode 37 is held at a relatively high potential, the pixel electrode 35 is held at a relatively low potential, and the pixel electrode 35 is made negative with respect to the potential of the common electrode 37. To do. Thereby, the negatively charged white particles 27 are attracted to the common electrode 37 side, and white is visually recognized when viewed from the display surface side.

FIG. 4 shows two examples of the overall configuration of the electrophoretic display device 100.
In the example shown in FIG. 4A, the element substrate 30 has a larger planar dimension than the counter substrate 31 that is an electrophoretic sheet, and two scans are performed on the element substrate 30 protruding outward from the counter substrate 31. The line drive circuit 61 and the two data line drive circuits 62 are mounted on COG (Chip On Glass). In addition, a terminal formation region 110 is provided in the edge portion in the vicinity of the data line driving circuit 62, and a flexible substrate 201 for connecting to an external device is provided in the terminal formation region 110 with an ACP (anisotropic conductive paste). It is bonded via ACF (anisotropic conductive film).

  In the example shown in FIG. 4A, the display unit 5 is formed in a region where the element substrate 30 and the counter substrate 31 overlap, and the scanning lines 66 and the data lines 68 extending from the display unit 5 are included in the scanning line driving circuit 61. The data line driving circuit 62 is extended to a region where the data line driving circuit 62 is mounted, and is connected to a connection terminal formed in the mounting region. A scanning line driving circuit 61 and a data line driving circuit 62 are mounted on the connection terminals via ACPs and ACFs.

  On the other hand, in the example shown in FIG. 4B, the scanning line driving circuit 61 and the data line driving circuit 62 are not mounted on the element substrate 30 and are mounted on the flexible substrates 202 and 203 by COF (Chip On Film) ( Or TAB (Tape Automated Bonding) mounting). Then, the flexible substrate 202 on which the scanning line driving circuit 61 is mounted is mounted on the terminal formation region 120 formed on the edge portion along one short side of the element substrate 30 via the ACP or the like. In addition, the flexible substrate 203 on which the data line driving circuit 62 is mounted is mounted on the terminal formation region 130 formed on the edge portion along one long side of the element substrate 30 via the ACP or the like. A plurality of connection terminals are formed in each of the terminal formation regions 120 and 130, and a scanning line 66 and a data line 68 extending from the display unit 5 are connected to each connection terminal. Further, the flexible substrate 203 on which the data line driving circuit 62 is mounted is also connected to the rigid substrate 204, and the flexible substrate 205 for external connection is connected to the rigid substrate 204.

Next, the configuration of the element substrate 30 (electro-optical device substrate) which is the essence of the present invention will be described.
In the element substrate 30, as shown in the plane pattern of FIG. 5, the data lines 68 extending in the vertical direction of FIG. 5 and the scanning lines 66 extending in the horizontal direction of FIG. One pixel 40 is a region partitioned by the two data lines 68 and two adjacent scanning lines 66. A selection transistor 41 made up of two TFTs, a first TFT 72 and a second TFT 73, is provided at one corner of the rectangular pixel 40, and in a region overlapping the selection transistor 41, the data line 68, and a part of the scanning line 66 in a plane. A rectangular pixel electrode 35 is provided.

  The gate electrodes 74 and 75 of the first TFT 72 and the second TFT 73 are respectively formed branched from the scanning line 66, and the semiconductor layer 76 is formed so as to straddle the gate electrode 74 of the first TFT 72 and the gate electrode 75 of the second TFT 73. Yes. A source electrode 77 of the first TFT 72 is formed so as to branch from the data line 68 and partially overlap the gate electrode 74 of the first TFT 72. An electrode 78 serving as both the drain electrode of the first TFT 72 and the source electrode of the second TFT 73 so as to partially overlap the gate electrode 74 of the first TFT 72 and the gate electrode 75 of the second TFT 73 (this electrode will be referred to as source / source A drain electrode 78).

  A drain electrode 79 of the second TFT 73 is formed so as to partially overlap the gate electrode 75 of the second TFT 73. One end of the drain electrode 79 opposite to the side overlapping the gate electrode 75 extends long and overlaps a second storage capacitor electrode 80B (second storage capacitor lower electrode) described later. A portion of the drain electrode 79 that overlaps the second storage capacitor electrode 80B functions as a second storage capacitor upper electrode.

  That is, when the first TFT 72 and the second TFT 73 are considered as one selection transistor 41, the source electrode 77 of the first TFT 72 branched from the data line 68 corresponds to the source electrode of the selection transistor 41, and 2 of the first and second TFTs 72 and 73. The two gate electrodes 74 and 75 correspond to the gate electrode of the double gate type selection transistor 41, and the drain electrode 79 of the second TFT 73 corresponds to the drain electrode of the selection transistor 41.

  A first storage capacitor electrode 80 </ b> A is formed across a plurality of pixels 40 over substantially the entire surface of the display unit 5 on the element substrate 30. Therefore, in FIG. 5, the first storage capacitor electrode 80A does not appear, but only the opening 80AC of the contact hole portion described later appears. That is, the first storage capacitor electrode 80A overlaps with the first TFT 72, the second TFT 73, and part of the wiring such as the data line 68, the scanning line 66, and the second capacitor line 67B in a plan view. The portion where the first storage capacitor electrode 80A overlaps the pixel electrode 35 in plan view becomes the first storage capacitor 71A of each pixel 40. In the case of the present embodiment, since the first storage capacitor electrode 80A is formed over substantially the entire surface of the display unit 5, the entire region where the pixel electrode 35 is formed overlaps with the first storage capacitor electrode 80A. It functions as 71A. In addition, since the first storage capacitor electrode 80A is formed over substantially the entire surface of the display unit 5, a linear pattern as the first capacitor line is not formed, and the first storage capacitor electrode 80A is shared from the periphery thereof. A potential is applied.

  A second capacitor line 67B is disposed substantially parallel to the scanning line 66 so as to extend in the lateral direction of FIG. 5. Within each pixel 40, a second storage capacitor electrode 80B is provided with a drain electrode 79 and a pixel electrode 35. Are formed integrally with the second capacitor line 67B. A portion where the second storage capacitor electrode 80B overlaps with a part of the drain electrode 79 in plan view becomes a second storage capacitor 71B of each pixel 40. Therefore, the area of the first storage capacitor 71A formed by the overlapping portion of the first storage capacitor electrode 80A and the pixel electrode 35 is the area of the second storage capacitor 71B formed by the overlapping portion of the second storage capacitor electrode 80B and the drain electrode 79. Bigger than.

  Further, the drain electrode 79 and the pixel electrode 35 overlap each other, and a contact hole 81 for electrically connecting the drain electrode 79 and the pixel electrode 35 is formed in this overlapping portion. The contact hole 81 is formed in the opening 80AC of the first storage capacitor electrode 80A.

FIG. 6 shows a cross-sectional structure of the first TFT 72, the second TFT 73, the first storage capacitor 71A, and the second storage capacitor 71B described above. Further, the left side of the omitted portion in FIG. 6 shows the cross-sectional structure of the pixel 40, and the right side shows the cross-sectional structure of a part of the peripheral circuit portion 86 (protection circuit portion).
As shown in FIG. 6, on the surface of the substrate body 82 constituting the element substrate 30 on the side where the electrophoretic element 32 is disposed, the selection transistor 41 including the first TFT 72 and the second TFT 73, the pixel electrode 35, and the first storage capacitor. An electrode 80A, a second storage capacitor electrode 80B, a scanning line 66, a data line 68, and the like are formed.

  On the substrate body 82, gate electrodes 74 and 75 made of a first conductive film are formed. Although not shown in FIG. 6, the scanning line 66 integrated with the gate electrodes 74 and 75 is also formed on the substrate body 82. On the substrate body 82, a second storage capacitor electrode 80B made of the first conductive film in the same layer as the gate electrodes 74 and 75 is formed. Although not shown in FIG. 6, the second capacitor line 67 </ b> B integrated with the second storage capacitor electrode 80 </ b> B is also formed on the substrate body 82. The substrate main body 82 is a substrate made of glass, plastic, or the like, and is disposed on the side opposite to the image display surface. In particular, when an organic TFT having an organic semiconductor layer is used as the selection transistor 41, it is desirable to use a plastic substrate that is inexpensive, lightweight, and excellent in flexibility. Further, as the material of the first conductive film constituting the gate electrodes 74 and 75, the scanning line 66, and the second storage capacitor electrode 80B, for example, a metal laminated film of an Al—Nd alloy and Mo can be used. In addition, Al alone, ITO, Cu, Cr, Ta, Mo, Nb, Ag, Pt, Pd, In, Nd, and alloys thereof can be used.

  A gate insulating film 83 made of a first insulating film is formed on the entire surface of the substrate body 82 so as to cover the gate electrodes 74 and 75 and the second storage capacitor electrode 80B. As a material of the first insulating film constituting the gate insulating film 83, for example, a silicon nitride film having a film thickness of 300 nm can be used. As other materials, inorganic insulating materials such as silicon oxide films and silicon oxynitride films, and organic insulating materials can be used. A portion of the gate insulating film 83 sandwiched between the second storage capacitor electrode 80B and the drain electrode 79 functions as a second storage capacitor insulating film of the second storage capacitor 71B.

A semiconductor layer 76 made of amorphous silicon is formed on the upper surface of the gate insulating film 83 above the gate electrodes 74 and 75. Furthermore, N ⁺ semiconductor layers 84 in which N-type impurities such as phosphorus are introduced into amorphous silicon are formed at both ends of the semiconductor layer 76, and each N ⁺ semiconductor layer 84 functions as a source region and a drain region. As a material of the semiconductor layer 76, in addition to amorphous silicon, for example, non-single crystal silicon material such as polycrystalline silicon, oxide semiconductor material, transparent oxide semiconductor material such as In—Ga—Zn—O, fluorene-bithiophene, etc. Organic semiconductor materials such as coalescence can be used. When an oxide semiconductor material is used for the semiconductor layer 76, it is desirable to use an oxide insulating material for the gate insulating film 83 (first insulating film). When an organic semiconductor material is used for the semiconductor layer 76, the gate insulating film is used. It is desirable to use an organic insulating material for 83 (first insulating film).

On the gate insulating film 83, a source electrode 77, a source / drain electrode 78, and a drain electrode 79 made of a second conductive film are formed so as to partially run over the upper surface of the semiconductor layer 76. The source electrode 77, the source / drain electrode 78, and the drain electrode 79 are electrically connected to the source region and the drain region of each of the TFTs 72 and 73 by making direct contact with the N ⁺ semiconductor layer 84. That is, as the first TFT 72 and the second TFT 73 of this embodiment, so-called bottom gate / top contact type TFTs are employed. A portion of the drain electrode 79 located above the second storage capacitor electrode 80B across the gate insulating film 83 functions as a second storage capacitor upper electrode. As a material of the second conductive film constituting the source electrode 77, the source / drain electrode 78, and the drain electrode 79, for example, a metal laminated film such as Mo / Al / Mo can be used. In addition, the same material as the first conductive film constituting the gate electrodes 74 and 75 can be used.

  A first protective film 85A made of an insulating film is formed on the entire surface of the gate insulating film 83 so as to cover the source electrode 77, the source / drain electrode 78, and the drain electrode 79. As a material of the insulating film constituting the first protective film 85A, an insulating material similar to the first insulating film such as an inorganic insulating material such as a silicon nitride film or a silicon oxide film can be used. A planarizing film 92 made of an organic material such as an acrylic resin is formed on the first protective film 85A. The planarizing film 92 is for planarizing the substrate surface by filling the steps reflecting the shapes of the first TFT 72, the second TFT 73, and the second storage capacitor 71B, and has a film thickness (for example, several μm) sufficient to fill the steps. Have.

  On the upper surface of the planarizing film 92, a first storage capacitor electrode 80A made of a light-shielding metal film is formed. In addition to the first TFT 72 and the second TFT 73 shown in FIG. 6, the first storage capacitor electrode 80A is also formed above the wiring such as the data line 68, the scanning line 66, and the second capacitor line 67B not shown in FIG. ing. As a material for the light-shielding metal film, for example, a metal laminated film of an Al—Nd alloy and Mo can be used. In addition, Al alone, Cu, Cr, Ta, Mo, Nb, Ag, Pt, Pd, In, Nd, and alloys thereof can be used.

  A second protective film 85B (first storage capacitor insulating film) made of a second insulating film is formed on the entire surface of the substrate so as to cover the first storage capacitor electrode 80A. In the present embodiment, the second protective film 85B is formed of a silicon nitride film having a thickness of 100 nm. Therefore, the thickness of the second insulating film constituting the second protective film 85B is set to be smaller than the thickness of the first insulating film constituting the gate insulating film 83. In addition, as a material of the second insulating film constituting the second protective film 85B, an insulating material similar to the first insulating film such as an inorganic insulating material such as a silicon oxide film can be used.

  In addition, a contact hole 81 reaching the drain electrode 79 through the second protective film 85B, the planarizing film 92, and the first protective film 85A is formed, and the pixel electrode is formed on the second protective film 85B including the inside of the contact hole 81. 35 is formed. With this configuration, the drain electrode 79 and the pixel electrode 35 are electrically connected via the contact hole 81. As a material of the pixel electrode 35, for example, a transparent conductive material such as ITO can be used. Alternatively, since the pixel electrode 35 is located on the opposite side to the viewing side with respect to the electrophoretic element 32, it may not be a transparent material, and a metal material such as Al may be used. Moreover, you may use these laminated films.

  FIG. 6 illustrates a protection circuit unit as an example of the peripheral circuit unit 86. The protection circuit section includes a first electrode 87 made of the first conductive film in the same layer as the gate electrodes 74 and 75, a second electrode 88 made of the second conductive film in the same layer as the source electrode 77 and the like, and the first electrode 87. And a short-circuit wiring 89 that electrically short-circuits the second electrode 88.

Hereinafter, a manufacturing process of the element substrate having the above configuration will be described.
First, a first conductive film made of a metal laminate film of Al—Nd with a thickness of 150 nm and Mo with a thickness of 20 nm is formed on one surface of a substrate body 82 such as glass or plastic by sputtering.
Next, the first conductive film is patterned by photolithography and etching to form the scanning line 66, the gate electrodes 74 and 75, the second storage capacitor electrode 80B, and the second capacitor line 67B.

Next, by a plasma CVD method, a silicon nitride film with a thickness of 300 nm that becomes the gate insulating film 83 (first insulating film), a non-doped amorphous silicon film with a thickness of 150 nm that becomes the semiconductor layer 76, and a film that becomes the N ⁺ semiconductor layer 84 Three layers of amorphous silicon film doped with phosphorus having a thickness of 50 nm are continuously formed without breaking the vacuum in the chamber. The first and second TFTs 72 and 73 of this embodiment are inverted stagger type, and in particular, a clean interface can be obtained by continuously forming the gate insulating film 83 and the semiconductor layer 76 serving as a channel region, thereby reproducing TFT characteristics. And stability are improved.

Next, among the three layers formed in the previous step by photolithography and etching, the non-doped amorphous silicon film and the phosphorus-doped amorphous silicon film are selectively patterned leaving the gate insulating film 83, and the semiconductor layer 76 and N ⁺ Semiconductor layer 84 is formed. Etching in this step employs dry etching using an etching gas containing SF ₆ . At this time, it is desirable to minimize damage to the gate insulating film 83 by using the plasma mode.

Next, a second conductive film made of a metal laminated film of 5 nm thick Mo, 150 nm thick Al, and 50 nm thick Mo is formed from the lower layer side by sputtering.
Next, the second conductive film is patterned by photolithography and etching to form a source electrode 77, a source / drain electrode 78, and a drain electrode 79.
Next, the N ⁺ semiconductor layer 84 between the source electrode 77 and the source / drain electrode 78 of the first TFT 72 and between the source / drain electrode 78 and the drain electrode 79 of the second TFT 73 is selectively removed by dry etching, and the source The region and the drain region are separated.

Next, a silicon nitride film to be the first protective film 85A is formed by plasma CVD.
Next, a photosensitive acrylic resin is applied and exposed to form a planarizing film 92.
Next, after forming a light-shielding metal film by a sputtering method, the light-shielding metal film is patterned by a photolithography method and an etching method to form the first storage capacitor electrode 80A.
Next, after a 100 nm-thickness silicon nitride film to be the second protective film 85B is formed by plasma CVD, the silicon nitride film in a region that later becomes a contact hole is selectively removed on the drain electrode.
Finally, after forming a conductive film by a sputtering method, the conductive film is patterned by a photolithography method or a wet etching method to form a pixel electrode 35.
The element substrate 30 of this embodiment is completed through the above steps.

  In the present embodiment, the first storage capacitor 71A does not use a capacitor electrode or a gate insulating film formed in the same layer as the scanning line as described in the conventional patent documents 1 and 2, and more than these. The upper layer side film, that is, the first storage capacitor electrode 80A, the second protective film 85B, and the pixel electrode 35 is formed. Therefore, the characteristics of the first storage capacitor 71A are designed independently of the characteristics of the selection transistor 41 including the first TFT 72 and the second TFT 73 by appropriately setting the film thickness and relative dielectric constant of the second protective film 85B. Can do. That is, the first storage capacitor 71A having a sufficient capacitance value can be formed without being restricted by the characteristics of the selection transistor 41. Further, the first storage capacitor 71A is stacked on the second storage capacitor 71B, and the sum of the capacitance values of the two storage capacitors becomes the storage capacitor value of the entire pixel. As a result, it is possible to realize an electrophoretic display device in which variations in feedthrough voltage are suppressed and display unevenness is small.

Here, the feedthrough voltage will be described with reference to FIGS. 7 (a) and 7 (b).
The TFT has a parasitic capacitance due to the structure. In FIG. 7A, a broken line capacitor symbol represents a parasitic capacitance, which is a gate-drain parasitic capacitance Cgd formed by the overlapping portion of the gate electrode and the drain electrode, and a channel when the TFT is in an ON state. This corresponds to about half of the capacity formed in the region. At this time, if the storage capacitance is Cst, the electrophoretic element capacitance is Cepd, the gate voltage high level is Vgh, and the low level is Vgl, the feedthrough voltage ΔVg is the gate-drain parasitic capacitance Cgd and the pixel capacitance Cpix (= Cgd + Cst + Cepd). ) And the ratio are expressed as follows.
ΔVg = (Cgd / Cpix) × (Vgh−Vgl)
= (Cgd / (Cgd + Cst + Cepd)) × (Vgh−Vgl) (1)

Further, the pixel effective voltage VPIX-VCOM when the feedthrough voltage ΔVg varies by ΔV due to manufacturing variations such as processing variations can be expressed as shown in FIG.
When the pixel effective voltage is expressed by a mathematical formula, the following formulas (2) and (3) are obtained, respectively, in the case of an AC drive liquid crystal display device and in the case of a DC drive electrophoretic display device.

  As apparent from the equations (2) and (3), in the case of the liquid crystal display device, there is almost no influence on the pixel effective voltage when the feedthrough voltage variation ΔV is ΔV <1. On the other hand, in the case of an electrophoretic display device, ± ΔV directly affects the variation in pixel effective voltage, and is recognized as display unevenness particularly in the case of halftone display. Therefore, in order to improve display uniformity, it is important to reduce the feedthrough voltage variation ΔV.

In order to reduce the feedthrough voltage variation ΔV, it is effective not only to suppress the variation of the gate-drain parasitic capacitance Cgd due to the manufacturing variation and the like, but also to increase the storage capacitance Cst from the equation (1). is there.
In that respect, in the electrophoretic display device 100 of the present embodiment, the second protective film 85B made of a silicon nitride film having a thickness of 100 nm is used as the first storage capacitor insulating film, so that the capacitance value per unit area can be increased. A sufficiently large storage capacity can be formed. As a result, since the feedthrough voltage variation ΔV can be reduced, fluctuations in pixel potential can be suppressed, and an electrophoretic display device with little display unevenness can be realized.
Since the storage capacitance value is related to the area of the overlapping portion between the pixel electrode 35 and the first storage capacitance electrode 80A, processing variations such as alignment variations between the pixel electrode 35 and the first storage capacitance electrode 80A can be reduced. It is desirable to design.

Next, energy consumption of the electrophoretic display device will be described.
In general, the power consumption P is expressed as P = fCV ² where f is the drive frequency, C is the capacitance, and V is the applied voltage. Most of the power P is data with a high drive frequency f and a large applied voltage V. Occupied by line drive. Since the driving voltage of the electrophoretic display device is, for example, about 15V, which is higher than about 5V of the liquid crystal display device, the power consumption for driving the data lines is larger than that of the liquid crystal display device. On the other hand, energy consumption is represented by the product of power consumption and driving time. In the case of an electrophoretic display device having display memory, refresh driving for maintaining display is unnecessary. Therefore, the energy consumption can be made smaller than that of the liquid crystal display device in the usage where the rewriting frequency is low.

  In that respect, in the electrophoretic display device 100 of the present embodiment, a sufficiently large storage capacitor can be formed, so that the pixel potential during a period required to change the display state can be reliably held. In other words, it is not necessary to write the storage capacitor a plurality of times, and the pixel potential can be reliably held only by writing once. Accordingly, since driving for refreshing the pixel voltage is not necessary, energy for charging the data line can be reduced, and energy consumption can be greatly reduced.

  Further, according to the configuration of the present embodiment, the first storage capacitor electrode 80A is formed of a light-shielding metal film, and the first storage capacitor electrode 80A covers the wiring such as the first TFT 72, the second TFT 73, and the data line 68. Is formed. For this reason, wiring such as the first TFT 72, the second TFT 73, and the data line 68 is shielded by the first storage capacitor electrode 80A and electrically shielded. Therefore, leakage current, potential fluctuation, and the like of the first TFT 72 and the second TFT 73 constituting the selection transistor 41 can be suppressed, and deterioration of TFT characteristics can be prevented.

  Further, in the case of the present embodiment, since the area of the first storage capacitor 71A is larger than the area of the second storage capacitor 71B, the overall storage capacitor value can be increased and the light shielding performance and electrical shielding performance can be further improved. . Further, the first storage capacitor electrode 80A is formed over the whole of the plurality of pixels 40, and substantially all of the first storage capacitor electrode 80A including the space between the rows of the plurality of pixels 40 is covered with the first storage capacitor electrode 80A. And electrical shielding performance can be further enhanced.

[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described with reference to FIGS. 9 and 10.
The electro-optical device of this embodiment is also an example of an active matrix type electrophoretic display device, as in the first embodiment.
The basic configuration of the electrophoretic display device of this embodiment is the same as that of the first embodiment, except that the shape of the first storage capacitor electrode is different.
FIG. 9 is a diagram showing a planar pattern of each pixel of the element substrate of the electrophoretic display device of this embodiment. FIG. 10 is an equivalent circuit diagram of each pixel of the electrophoretic display device.
9 and 10, the same reference numerals are given to the same components as those in FIGS. 2 and 5 used in the first embodiment, and detailed description thereof will be omitted.

  In the electrophoretic display device of the present embodiment, as shown in FIG. 10, each pixel 40A has two storage capacitors 71A and 71B connected in parallel to each other. One electrode of the first storage capacitor 71A and one electrode of the second storage capacitor 71B are electrically connected to the pixel electrode 35, and the other electrode of the first storage capacitor 71A and the other electrode of the second storage capacitor 71B. Are electrically connected to different capacitance lines 67A and 67B. This equivalent circuit is the same as that of the first embodiment.

  In the first embodiment, the first storage capacitor electrode 80 </ b> A is integrally formed on the entire surface of the display unit 5 over the entire plurality of pixels 40. On the other hand, in the present embodiment, as shown in a planar pattern in FIG. 9, the first storage capacitor electrode 80C is formed by being divided for each row of the plurality of pixels 40 arranged in a matrix. . That is, the first storage capacitor electrode 80 </ b> C is formed elongated along the direction in which the scanning line extends (lateral direction in FIG. 9) as indicated by the broken line. Other configurations are the same as those of the first embodiment.

Also in this embodiment, since a sufficiently large storage capacitor can be formed, it is possible to obtain the same effects as those in the first embodiment, such that an electrophoretic display device with less variation in feedthrough voltage and less display unevenness can be realized. it can.
Further, in the first embodiment, since the first storage capacitor electrode 80A is formed over the whole of the plurality of pixels 40, the same common potential is only given over the whole of the plurality of pixels 40. In contrast, according to the present embodiment, since the first storage capacitor electrode 80C is divided for each row of the plurality of pixels 40, the first storage capacitor electrode 80A (first It is possible to drive by individually controlling the potential of the capacitor line.

[Third Embodiment]
Hereinafter, a third embodiment of the present invention will be described with reference to FIGS.
The electro-optical device of this embodiment is also an example of an active matrix type electrophoretic display device, as in the first and second embodiments.
The basic configuration of the electrophoretic display device of this embodiment is the same as that of the first embodiment, and only the configuration of the storage capacitor is different.
FIG. 11 is a diagram showing a planar pattern of each pixel of the element substrate of the electrophoretic display device of this embodiment. 12 is a cross-sectional view taken along the line AA ′ of FIG. FIG. 13 is an equivalent circuit diagram of each pixel of the electrophoretic display device.
11 to 13, the same reference numerals are given to the same components as those in FIGS. 2, 5, and 6 used in the first embodiment, and detailed description thereof is omitted.

  The element substrates of the first and second embodiments have two storage capacitors, a first storage capacitor and a second storage capacitor, and the two storage capacitors are stacked to form a storage capacitor for the entire pixel. . On the other hand, the element substrate 30B of the present embodiment has only the first storage capacitor 71A. That is, the element substrate 30B of the present embodiment has a configuration in which the second storage capacitor is removed from the element substrate of the first embodiment.

  In the electrophoretic display device of this embodiment, as shown in the equivalent circuit diagram of FIG. 13, each pixel 40B has one storage capacitor (first storage capacitor 71A). One electrode of the first storage capacitor 71A is electrically connected to the pixel electrode 35, and the other electrode of the first storage capacitor 71A is electrically connected to the capacitor line 67. However, in the present embodiment as well, the first storage capacitor electrode 80A is formed over the entire pixel 40B as in the first embodiment. Therefore, even if there is a capacitor line on the equivalent circuit diagram, the pattern of the linear capacitor line Does not exist.

As shown in the plan pattern diagram of FIG. 11, the element substrate 30B of the present embodiment has no pattern of the second storage capacitor electrode 80B from the element substrate 30 of the first embodiment shown in FIG. Further, since the drain electrode 79B does not need to function as the second storage capacitor upper electrode, it is not necessary to have a portion that protrudes greatly as in the first embodiment shown in FIG. A contact hole 81 is formed.
Also in the cross-sectional structure, as shown in FIG. 12, the pattern of the second storage capacitor electrode 80B in the same layer as the gate electrode 74 and the like is eliminated from the element substrate 30 of the first embodiment shown in FIG. Others are the same as in the first embodiment.

Also in this embodiment, since a sufficiently large storage capacitor can be formed, the same effects as those in the first and second embodiments can be realized, in which variation in feedthrough voltage is further suppressed and an electrophoretic display device with less display unevenness can be realized. Obtainable.
Further, in the case of the present embodiment, since there is no second storage capacitor electrode in the same layer as the gate electrode 74 or the scanning line 66, a short circuit failure between the gate electrode 74 or the scanning line 66 and the second storage capacitor electrode may occur. Absent.

[Fourth Embodiment]
Hereinafter, a fourth embodiment of the present invention will be described with reference to FIG.
The electro-optical device of this embodiment is also an example of an active matrix type electrophoretic display device, as in the first to third embodiments.
The basic configuration of the electrophoretic display device of this embodiment is the same as that of the third embodiment, and only the configuration of the insulating film is different.
FIG. 14 is a cross-sectional view of an element substrate of the electrophoretic display device of this embodiment.
14, the same code | symbol is attached | subjected to the same component as FIG. 12 used in 3rd Embodiment, and detailed description is abbreviate | omitted.

  In the element substrate 30B of the third embodiment, as shown in FIG. 12, a first protective film 85A is formed so as to cover the first and second TFTs 72 and 73, and a planarizing film 92 is formed on the first protective film 85A. Thus, the first storage capacitor 71A composed of the first storage capacitor electrode 80A, the second protective film 85B, and the pixel electrode 35 is formed on the upper surface of the planarizing film 92. On the other hand, as shown in FIG. 14, in the element substrate 30C of this embodiment, the planarization film is not formed, and the first storage capacitor electrode 80A and the second protection film 85B are formed on the first protection film 85A. A first storage capacitor 71A composed of the pixel electrode 35 is formed. Others are the same as in the first embodiment.

Also in this embodiment, since a sufficiently large storage capacitor can be formed, the same effects as those in the first to third embodiments can be realized, in which variation in feedthrough voltage is further suppressed and an electrophoretic display device with less display unevenness can be realized. Obtainable.
Furthermore, in the case of this embodiment, it is not necessary to form a planarizing film, so that the manufacturing process can be simplified. Further, since the second storage capacitor electrode in the same layer as the gate electrode 74 and the scanning line does not exist, the short circuit failure between the gate electrode 74 and the scanning line and the second storage capacitor electrode does not occur. It is the same as the form.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above embodiment, an amorphous silicon TFT is used, but an oxide semiconductor TFT, an organic TFT, a polycrystalline silicon TFT, or the like may be used. Note that an oxide semiconductor TFT is higher in mobility than amorphous silicon, and can be downsized. Therefore, the oxide semiconductor TFT is preferable in that the parasitic capacitance between the gate and the drain can be reduced, and variation in feedthrough voltage can be reduced.
In addition, the specific configuration of each member of the electrophoretic display device, such as the material, film thickness, shape, and manufacturing method, is not limited to the above embodiment, and can be changed as appropriate.

  Furthermore, the present invention is more effective when combined with other techniques for increasing capacity density. For example, only the region for forming the storage capacitor in the gate insulating film may be thinned. According to this configuration, it is possible to reduce the power consumption while ensuring the breakdown voltage of the TFT and suppressing the leakage current. Specifically, as a method of thinning the gate insulating film, the gate insulating film has a two-layer structure, the first gate insulating film is formed on the entire surface, and then the first gate insulating film in the storage capacitor formation region is removed. In addition, a method of forming the second gate insulating film over the entire surface can be given. According to this method, since the film thickness variation of the entire gate insulating film in the storage capacitor formation region is only the film thickness variation of the second gate insulating film, the gate insulating film of one layer is etched halfway to reduce the thickness. The film thickness variation can be reduced as compared with the method.

[Electronics]
Next, a case where the electrophoretic display device 100 of the above embodiment is applied to an electronic device will be described.
FIG. 15 is a front view of the wrist watch 1000. The wrist watch 1000 includes a watch case 1002 and a pair of bands 1003 connected to the watch case 1002.
On the front surface of the watch case 1002, a display unit 1005 including the electrophoretic display device of each of the above embodiments, a second hand 1021, a minute hand 1022, and an hour hand 1023 are provided. On the side surface of the watch case 1002, a crown 1010 and an operation button 1011 are provided as operation elements. The crown 1010 is connected to a winding stem (not shown) provided inside the case, and is integrally provided with the winding stem so that it can be pushed and pulled in multiple stages (for example, two stages) and can be rotated. . The display unit 1005 can display a background image, a character string such as date and time, or a second hand, a minute hand, and an hour hand.

  FIG. 16 is a perspective view illustrating a configuration of the electronic paper 1100. An electronic paper 1100 includes the electrophoretic display device of the above embodiment in a display area 1101. The electronic paper 1100 is flexible and includes a main body 1102 made of a rewritable sheet having the same texture and flexibility as conventional paper.

  FIG. 17 is a perspective view showing the configuration of the electronic notebook 1200. An electronic notebook 1200 is obtained by bundling a plurality of the electronic papers 1100 and sandwiching them between covers 1201. The cover 1201 includes display data input means (not shown) for inputting display data sent from an external device, for example. Thereby, according to the display data, the display content can be changed or updated while the electronic paper is bundled.

According to the wristwatch 1000, the electronic paper 1100, and the electronic notebook 1200 described above, the electrophoretic display device according to the present invention is employed, so that the electronic apparatus is provided with display means capable of obtaining excellent reliability over a long period of time. .
In addition, said electronic device illustrates the electronic device which concerns on this invention, Comprising: The technical scope of this invention is not limited. For example, the electro-optical device according to the present invention can be suitably used for a display portion of an electronic device such as a mobile phone or a portable audio device.

  30, 30B, 30C ... element substrate (electro-optical device substrate), 35 ... pixel electrode, 40, 40A, 40B ... pixel, 41 ... selection transistor (pixel switching element), 66 ... scanning line, 67 ... capacitance line, 68 Data line, 71A ... First storage capacitor, 71B ... Second storage capacitor, 74, 75 ... Gate electrode, 76 ... Semiconductor layer, 77 ... Source electrode, 79, 79B ... Drain electrode, 80A ... First storage capacitor electrode, 80B ... second storage capacitor electrode, 83 ... gate insulating film, 85A ... first protective film, 85B ... second protective film (first storage capacitor insulating film), 100 ... electrophoretic display device, 1000 ... watch (electronic device) DESCRIPTION OF SYMBOLS 1100 ... Electronic paper (electronic device), 1200 ... Electronic notebook (electronic device).

Claims (11)

A substrate main body, a plurality of data lines and a plurality of scanning lines provided on the substrate main body, and a plurality of pixels partitioned by the data lines and the scanning lines. Each is a substrate for an electrophoretic display device comprising a pixel switching element, a pixel electrode, and a first storage capacitor,
The pixel switching element includes a gate electrode made of a first conductive film formed on the substrate body, a gate insulating film made of a first insulating film formed so as to cover at least the gate electrode, and the gate insulating film A semiconductor layer formed thereon; a source electrode made of a second conductive film electrically connected to the source region of the semiconductor layer and the data line; and a drain region of the semiconductor layer and the pixel electrode electrically A drain electrode made of the second conductive film connected,
A first storage capacitor electrode made of a light-shielding metal film formed on an upper layer side of the second conductive film; and a second insulating film formed so as to cover at least the first storage capacitor electrode. And a first storage capacitor insulating film formed so as to overlap at least part of the first storage capacitor electrode with the first storage capacitor insulating film interposed therebetween when viewed from the normal direction of the substrate body. The pixel electrode, and
The electricity is characterized in that when viewed from the normal direction of the substrate body, at least part of the first storage capacitor electrode overlaps with at least part of the pixel switching element and the wiring. Electrophoretic display substrate. Each of the plurality of pixels includes a second storage capacitor formed so that at least a portion thereof overlaps the first storage capacitor when viewed from the normal direction of the substrate body;
The second storage capacitor comprises a second storage capacitor lower electrode made of the first conductive film and a second storage capacitor insulation film made of the first insulation film so as to cover at least the second storage capacitor lower electrode. And when viewed from the normal direction of the substrate body, the second conductive film formed so that at least a portion thereof overlaps the second storage capacitor lower electrode with the second storage capacitor insulating film interposed therebetween The substrate for an electrophoretic display device according to claim 1, further comprising: a second storage capacitor upper electrode.   The area of the first storage capacitor composed of the overlapping portion of the first storage capacitor electrode and the pixel electrode is the second storage composed of the overlapping portion of the second storage capacitor lower electrode and the second storage capacitor upper electrode. The substrate for an electrophoretic display device according to claim 2, wherein the substrate is larger than an area of the capacitance.   4. The electrophoretic display device substrate according to claim 1, wherein a thickness of the second insulating film is smaller than a thickness of the first insulating film. 5.   5. The electrophoretic display device substrate according to claim 1, wherein the first storage capacitor electrode is formed over the whole of the plurality of pixels. 6.   5. The electrophoretic display according to claim 1, wherein the first storage capacitor electrode is divided and formed for each row of the plurality of pixels arranged in a matrix. 6. Device substrate.   The substrate for electrophoretic display devices according to claim 1, wherein the semiconductor layer is made of non-single crystal silicon.   The substrate for electrophoretic display devices according to any one of claims 1 to 6, wherein the semiconductor layer is made of an oxide semiconductor material.   The substrate for an electrophoretic display device according to claim 1, wherein the semiconductor layer is made of an organic semiconductor material. A pair of substrates, and an electrophoretic element sandwiched between the pair of substrates,
10. An electrophoretic display device, wherein one of the pair of substrates is the electrophoretic display device substrate according to claim 1.   An electronic apparatus comprising the electrophoretic display device according to claim 10.

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