This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2011-124674, filed on Jun. 2, 2011; the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention is related to a device which displays an image etc. In particular, the present invention is related to a device which displays an image etc. by adjusting the amount of light which passes through each pixel element corresponding to a pixel.
2. Description of the Related Art
A display device which uses liquid crystals is known as a device which displays an image etc. In this type of device, the amount of light which passes through a polarization plate is controlled for each pixel by controlling the polarization of light which passes through the liquid crystals sandwiched between electrodes. Here the polarization plate is arranged at a position of the liquid crystals corresponding to a pixel.
However, a display device which uses liquid crystals requires time to change the polarization of light which passes through the liquid crystals. As a result, when displaying an image etc. which changes at high speed, there is a problem in that viewers often recognize a residual image. In addition, because it is necessary to pass light through multiple layers such as a polarization plate, a liquid crystal layer, a color filter, an electrode, etc., the usage efficiency of the light decreases and it is difficult to obtain a bright display.
On the other hand, in recent years, display devices with mechanical shutters (hereinafter referred to as “MEMS shutters”), which are manufactured with MEMS (Micro Electro Mechanical Systems) technology, are gathering attention. A display device which uses MEMS shutters (hereinafter referred to as “a MEMS display device”) controls the amount of light which passes through each shutter on each pixel by rapidly opening and closing and thereby the brightness of an image is adjusted.
A time-ratio-scale method is adopted in the MEMS display device whereby an image is displayed by switching red, green, and blue light from an LED backlight in sequence. The MEMS display device does not require a polarization film or a color filter which are used in liquid crystal display devices and is characterized by having around ten times the usage efficiency of backlight light and half or less the power consumption compared to liquid crystal display devices and also has excellent color reproducibility. In addition, a MEMS display device can change the display of an image etc. at high speed.
For example, a display device is disclosed in Japanese Patent Laid Open 2008-197668 as an example of a MEMS display device in which a shutter which moves in a parallel direction to a substrate is arranged on each pixel. In such a display device, a compliant road beam which opposes a drive beam is connected on one surface in the movement direction of the shutter, a spring beam is connected on the other surface, a voltage is applied between the compliant road beam and the drive beam, and the amount of light which passes through is controlled whereby the shutter is moved.
However, in the display device disclosed in the above mentioned laid open, because the compliant road beam and drive beam are mechanically in contact it is necessary to insulate the compliant road beam and drive beam. As a result, it is necessary to form an insulation film on a side surface of the compliant road beam and a side surface of the drive beam. In addition, because the compliant road beam and the drive beam are mechanically in contact, the beams themselves deteriorate and the insulation films formed on the beams also deteriorate.
Therefore, a display device which moves a shutter without generating mechanical contact and controls the amount of light which passes through is provided as one embodiment of the present invention.
That is, a display device is provided as one embodiment of the present invention including a plurality of data lines supplied with potentials via a data driver, a plurality of gate lines supplied with a potential via a gate driver; and a display part which includes a pixel element corresponding to an intersection of a data line and a gate line on a substrate. The pixel element is arranged with a substrate connection part formed on the substrate, a shutter being formed above the substrate, a beam which connects the substrate connection part, a side surface of the light blocking part, and an electrode formed on the substrate separated from an exterior edge formed on an opposite side of the side surface of the shutter.
In addition, a display device is provided as one embodiment of the present invention in which the pixel element further includes a second electrode formed on the substrate, a part of the second electrode opposing another part of the exterior edge.
In addition, a display device is provided as one embodiment of the present invention including a plurality of data lines supplied with potentials via a data driver, a plurality of gate lines supplied with a potential via a gate driver, and a display part which includes a pixel element, the pixel element corresponding to an intersection of a data lines and a gate line on a substrate, wherein each of the pixel elements is arranged with a substrate connection part formed on the substrate; a shutter formed above the substrate, the shutter including a light blocking element, a first side surface, and an exterior edge arranged on an opposite side to the first side surface; a beam which connects the substrate connection part and a side surface of the light blocking part; and a plurality of electrodes formed on the substrate separated from the exterior edge.
A display device related to the present invention is explained below in a plurality of embodiments. Furthermore, the present invention is not limited to these embodiments and can be performed by making various modifications in the embodiments. In addition, some film thicknesses or some distances between structural elements etc. in the drawings may be exaggerated and shown differently to actual components.
A functional block diagram of a display device related to the present embodiment is shown in
Referring to
The controller 101 receives an image signal. In order to display an image representing the image signal, the controller 101 determines a scanning line for display and after determining the brightness of pixels on the scanning line supplies a signal representing the brightness of the pixels on the scanning line to the data drier 103 and supplies a signal representing the scanning line determined by the gate driver 102. Furthermore, the controller 101 controls the production of each RGB light respectively from the backlight part 104. The light produced by the backlight part 104 can pass through the display part 105. As explained below the amount of light which passes through the display part 105 is controlled by a mechanical shutter 106a of a pixel 106.
The gate driver 102 selects the gate line corresponding to the scanning line determined by the controller 101 and supplies a potential to the selected gate line.
The gate driver 103 supplies potentials corresponding to the brightness of pixels on the data lines on the scanning line determined by the controller 101.
The display part is arranged with a plurality of gate lines G1, G2, . . . , Gn and a plurality of data lines D1, D2, . . . , Dm. The plurality of gate lines G1, G2, . . . , Gn and the plurality of data lines D1, D2, . . . , Dm alternately intersect each other. A pixel 106 is arranged at each intersection point of one of the plurality of gate lines G1, G2, . . . , Gn and one of the plurality of data lines D1, D2, . . . , Dm. A mechanical shutter 106a and a switching element 106b are arranged on the pixel 106.
The mechanical shutter 106a controls the amount of light which passes through an aperture part of the display part 106 corresponding to a pixel 106. The structure of the mechanical shutter 106a related to the present embodiment is explained below.
The switching element 106b controls transfer of a voltage supplied to the data line to the mechanical shutter 106a. The switching element 106b is a transistor such as a thin film transistor. In
The condenser 106c continues to supply a potential to the mechanical shutter 106c even while the gate line is not selected by the gate driver 102.
Referring to
The display part 113a includes a plurality of pixels 106 arranged in a matrix and a pixel includes a mechanical shutter 106a, a switching element 106b and a condenser 106c. The drive circuits 113b and 113c are data drivers 103. The drive circuits 113b and 113c supply a data signal to the switching elements 106b. A drive circuit 113d is the gate driver 102 and the drive circuit 113d supplies a data signal to the switching elements 106b. Furthermore, in
In
Referring to
The shutter 204 is formed from a material which does not allow light to pass through. In addition, the shutter 204 is formed parallel to the substrate of the display part 105. The shutter 204 has a shape in which a section that is closer to the center of a circle than the arc of the circle is removed from a shape enclosed by the two radiuses of the circles (in other words a fan shape) as is shown in
The beam 205 connects the shutter 204 and the substrate connection part 206. The beam 205 is preferred to have a shape which can bow and be deformed. That is, it is preferred that the beam 205 have a shape which can undergo deformation so that it is possible to move the shutter 204 in a parallel direction to the substrate of the display part 105. For example, as is shown in
The substrate connection part 206 is the part formed by connecting to the substrate of the display part 105. The substrate connection part 206 is a part for holding the shutter 204 away from the surface of the substrate 111 of the display part 105 via the beam 205. In addition, the substrate connection part 206 may be able to be deformed by being twisted according to the movement of the shutter 204 in the case where the shutter 204 moves in a horizontal direction with respect to the top of the substrate 111. In this way, it is possible to reduce the size of the transformation of the beam 205. In addition, it is possible to prevent damage to the beam due to deformation. Alternatively, it is possible to ensure that the amount of movement of the shutter 204 becomes larger due to the deformation of the substrate connection part 206 in addition to the deformation of the beam 205.
Furthermore, the substrate connection part 206 and the exterior edge part 203 are electrically connected via the beam 205 and the shutter 204. Because of this, the movable part 201 is formed using a conductive material such as amorphous silicon etc.
The fixed electrode 202 is an electrode formed on the substrate of the display part 105. The fixed electrode 202 is shown with a roughly round arc shape in
A cross sectional view along the line I-I in
A cross sectional view along the line II-II in
The potential of the wiring 211 is maintained at a ground potential by connecting the wiring 211 to a common electrode of the display part 105. In addition, by connecting the wiring 213 to a data line via the switching element 106b, a potential supplied to the data line is supplied to the wiring 213 according to a selection of the gate line by the gate driver 102. Alternatively, the wiring 211 may be connected to the data line via the switching element 106b and the wiring 213 may be connected to the common electrode of the display part 105.
Furthermore, the following can be given as an example of a formation method of the mechanical shutter related to the present embodiment. That is, the wiring 211 and the wiring 213 are formed above the substrate 111 of the display part 105 and the insulation film 212 is further formed according to necessity.
Next, a photo resist, which becomes a sacrifice layer, is stacked and following this and the photo resist is patterned into the shape of a support part of the substrate connection part 206 and the fixed electrode 206. A material of the substrate connection part 206 (amorphous silicon for example) is formed as a layer above the patterned photo resist. Following this, etching of the sacrifice layer is performed and the support part of the substrate connection part 206 and the fixed electrode 202 is formed.
Furthermore, as described above, a photo resist (that is, a sacrifice layer) is formed and following this, the photo resist is patterned into a shape of the beam 205, the shutter 204, and an electrode part of the fixed electrode 202. A material (amorphous silicon for example) of the shutter 204 and the beam 205 is formed an upper layer of patterned photo resist and following this the sacrifice layer is etched and the beam 205, the shutter 204, and the electrode part of the fixed electrode 202 are formed.
Furthermore, the sacrifice later may be removed in one batch by etching after the substrate connection part 206, the support part of the fixed electrode 202, the beams 205, the shutter 204, and the electrode part of the fixed electrode 202 are formed in one batch.
In addition, a film may be formed above the shutter 204 using a metal layer material such as aluminum etc. in order to improve light blocking capabilities of the shutter 204.
Therefore, seen from the uppers surface of the substrate 210, the aperture part 301 can be arranged as follows. That is, it is possible to arrange an aperture part 301 at a part of the substrate 111 of the display part 105 which is covered by the shutter 204 in the state shown in
As described above, in the present embodiment, it is possible to control a potential supplied to the exterior edge part 203 and a potential supplied to the fixed electrode 202, transit between a state where the beam 205 and/or substrate connection part 206 undergo deformation and a state where the beam 205 and/or substrate connection part 206 do not undergo deformation, and ensure that the movable part 201 and the fixed electrode 202 do not contact. In this way, it is possible to prevent the movable part 201 and the fixed electrode 202 from deteriorating, it is no longer necessary to form an insulation film on the exterior edge part 203 and the side surface of the fixed electrode 202, and the manufacturing process becomes simplified. In particular, a process for arranging an aperture on an insulation film formed on the terminal 114a is no longer necessary.
Because the amount of light which passes through the aperture part 301 is controlled per unit of time by controlling the length of time during which a potential difference is produced between the exterior edge part 203 and the fixed electrode 202, it is possible to make a person viewing the display part 105 recognize as if the brightness of an image is being controlled.
Furthermore, the larger the difference between the potential supplied to the exterior edge part 203 and the potential supplied to the fixed electrode 202, the larger the electrical attraction force which attracts the shutter 204 to the fixed electrode 202 and thereby the amount of transmittance light can be controlled by controlling the difference between the potential supplied to the exterior edge part 203 and the potential supplied to the fixed electrode 202.
Furthermore, when the display part 105 is filled with oil according to necessity, electrostatic capacitance of a condenser, which is formed with the exterior edge part 202 and the fixed electrode 202, increases. In this way, it is possible to increase the electrical attraction force which attracts the shutter 204 to the fixed electrode 202 and thereby it is possible to realize a shutter which can open and close more rapidly.
A structure of a mechanical shutter which uses a plurality of fixed electrodes is disclosed as embodiment two of the present invention.
An upper surface view of the mechanical shutter 400 used in the pixel 106 of the display device related to embodiment two of the present invention is shown in
The movement of the mechanical shutter 400 is explained with reference to
In this case, an electrical attraction force which attracts the shutter 204 towards the fixed electrode 202 is applied to the shutter 204, and the beam 205 and/or the substrate connection part 206 undergo deformation. As a result, the shutter 204 moves in a clockwise direction as is shown in
In addition, by making the potential supplied to the substrate connection part 206 and the potential supplied to the fixed electrode 202 the same (a ground potential for example), and supplying a positive potential to the fixed electrode 401, the electrical attraction force which attracts the shutter 204 towards the fixed electrode 401 becomes larger than the electrical attraction force which attracts the shutter 204 towards the fixed electrode 202. Then, the shutter 204 moves in the reverse direction to
Therefore, it is possible to arrange an aperture part 501 as follows. That is, it is possible to arrange the aperture part 501 on a part which is not covered by the shutter 204 in the state shown in
In the present embodiment, because the fixed electrode 401 is further arranged, it is possible to further increase the amount by which the shutter 204 moves. In this way, it is possible to make the aperture part 501 in the present embodiment larger than the aperture part 301. Therefore, it is possible to pass more light through to each pixel and display a brighter image.
The movement of the shutter 600 in the case where different potentials are supplied to the fixed electrodes 601-610 is shown in
Therefore, as is shown in
An embodiment is disclosed in which a plurality of apertures are arranged on the shutter 204 in the embodiments described above as embodiment three of the present invention.
An upper surface view of a mechanical shutter 800 for in the pixel 106 of a display device related to embodiment three of the present invention is shown in
The movement of the mechanical shutter 800 is explained while referring to
In this case, a greater force than the electrical attraction force which attracts the shutter 204 towards the fixed electrode 801 is applied and the beam 205 and/or substrate connection force 206 undergo deformation. As a result, the shutter 204 rotates in an anti-clockwise direction as is shown in
Alternatively, it is possible to make the force which attracts the shutter 204 towards the fixed electrode 802 be greater than the force which attracts the shutter 204 towards the fixed electrode 801. In this case, a force which attracts the shutter 204 towards the fixed electrode 802 is applied and the beam 205 and/or the substrate connection part 206 undergo deformation. As a result, the shutter 204 rotates in a clockwise direction as is shown in
Therefore, because the amount of light which passes through the aperture 803 and the aperture 804 is different, a two level gradation of amount of transmittance light can be controlled. In addition, because it is possible to reduce the amount by which the shutter 204 moves, it is possible to more rapidly switch the display of an image.
Furthermore, in the present embodiment, while the case where two apertures are arranged on the shutter 204 is disclosed, transmittance light with an arbitrary number of gradations larger than two can be controlled by arranging an arbitrary number of apertures of three or more.
As described above, because a shutter is driven without using a contacting beam using the embodiments of the present invention, it is possible to provide a display device which controls the amount of light of each pixel using a shutter without using a process for forming an insulation film. In addition, a display device is also possible without generating a deterioration of a beam insulation film.
Number | Date | Country | Kind |
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2011-124674 | Jun 2011 | JP | national |