Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
  • G02B26/02—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the intensity of light
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
  • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
  • G02B26/0816—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements
  • G02B26/0833—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD
  • G02B26/0841—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD the reflecting element being moved or deformed by electrostatic means

Definitions

• the present invention relates to a display device that uses a mechanical shutter (referred to as “MEMS shutter” hereinafter) that employs microelectromechanical system (MEMS) technology.
• MEMS shutter a mechanical shutter
• MEMS microelectromechanical system
• MEMS display device for each pixel, an aperture through which backlight passes is formed on an aperture plate and a MEMS shutter is provided so as to cover each aperture.
• MEMS shutters By means of the MEMS shutters being opened and closed at high speed using transistors and by adjusting the ratio of opening and closing duration thereof, the quantity of light transmitted per tiny unit of time is controlled, and the luminance of each pixel is thereby adjusted (Patent Reference 1 , Patent Reference 2).
• FIG. 11 is a cross-sectional view of any one pixel in such a MEMS display device.
• a MEMS display device 500 has a MEMS substrate 510 having, as the main constituents, a shutter plate 502 provided on a transparent TFT substrate 501, and an aperture plate (not illustrated).
• This shutter plate 502 is supported at a distance of approximately 4 ⁇ from the top face of the TFT substrate 501 such that it can move between the two positions in parallel with the top face of the TFT substrate 501.
• anchors 503 having the same height as the top face of the shutter plate 502 supported as described above are formed in four locations outside the range of movement of each shutter plate 502 on the top face of the TFT substrate 501, as shown in FIG. 11.
• a spring 504 bridged between the shutter plate 502 and each anchor, there is a spring 504 to which an energizing force is applied in a direction causing them to approach each other.
• Each spring is respectively attached near the two ends of each edge in the direction of movement on the shutter plate 502.
• the shutter plate 502 can be selectively moved between the two positions in parallel with the surface of the TFT substrate 501.
• wiring for supplying drive voltage to each shutter plate 502 is laid on the surface of the TFT substrate 501 of the MEMS substrate 510, as shown in FIG. 1 1.
• an aperture plate (not illustrated) is constituted by means of an opaque film by which the aperture of each shutter plate 502 is closed being formed on a glass substrate. Furthermore, each aperture is blocked by the corresponding shutter plate 502 when the shutter plate 502 is in the first position, but when the shutter plate 502 is in the second position, it has a shape that is not blocked by the shutter plate 502.
• silicone oil is loaded between the TFT substrate 501 of the MEMS substrate 510 and the aperture plate (not illustrated).
• a backlight unit (not illustrated) is attached on the side edge face or rear face of the glass substrate that constitutes the aperture plate (not illustrated), and from this backlight unit, backlights of the primary colors red (R), green (G) and blue (B) are introduced into the glass substrate while being sequentially switched for each phase.
• the primary-color backlights propagate in the entire area in the glass substrate by repeated reflection, and are emitted toward the MEMS substrate 510 through each aperture.
• the backlight reaches the eye of the viewer if the shutter plate 502 is in the second position, and an image is formed on the retina of the viewer by the backlight which is selectively blocked or transmitted by each shutter plate 502.
• These shutter plates are manufactured to be in a moderately high suspended state (referred to hereinafter as "mid-air state") by forming amorphous silicon by chemical vapor deposition on photoresist forming a mold corresponding to the shape of the shutter plates, and then removing the amorphous silicon by dry etching, and then removing the remaining photoresist.
• the shutter plates 502 and springs 504 may be charged by the effect of static electricity during these processes. When charged in this manner, electrostatic force acts between the shutter plates 502 and springs 504 and the TFT substrate 501, and as a result, the shutter plates 520 and springs 504 are attracted to the TFT substrate 501, as shown in FIG. 12.
• the problem of the present invention is to provide a display device in which a spring and a shutter in the mid-air state during the production process can be prevented from adhering even when they contact wiring on the substrate due to the action of some external force.
• the display device is a display device having a structure in which a backlight unit which emits light and a MEMS shutter which controls the amount of light emitted from the backlight unit by opening and closing are provided on a transparent substrate, comprising wiring formed as a metal layer on the transparent substrate, and an insulating film at a location which overlaps the MEMS shutter in a direction orthogonal to the surface of the transparent substrate at least on the surface of the wiring.
• the insulating film may also be formed on the entire surface of the wiring, and it may be formed also on the sidewalls, and it may be formed so as to also cover the surface of the transparent substrate.
• the MEMS shutter may have a shutter plate which, by moving between two positions, blocks light emitted from the backlight unit when at a first position and transmits light emitted from the backlight unit when at a second position, and a plurality of springs which move the shutter plate between the two positions and also hold it in a mid-air state separated from the surface of the transparent substrate.
• the insulating film may also be formed at a location that overlaps the springs in a direction orthogonal to the surface of the transparent substrate on the surface of the wiring.
• the wiring and shutters or springs can be prevented from adhering to each other because the intermolecular force between the shutters and springs is reduced by the insulating film which covers the wiring.
• FIG. 1 is a drawing illustrating a MEMS display device pertaining to a first embodiment, wherein (a) is an oblique view of the MEMS display device, and (b) is a plan view of the MEMS display device.
• FIG. 2 is a circuit block diagram of the display device pertaining to the first embodiment.
• FIG. 3 is an oblique view illustrating the constitution of a MEMS shutter used in the display device pertaining to the first embodiment.
• FIG. 4 is a plan view of a MEMS substrate according to the first embodiment.
• FIG. 5 is a cross-sectional view illustrating a longitudinal cross-section of the MEMS substrate along line V-V of FIG. 4.
• FIG. 6 is a longitudinal cross-sectional view illustrating the production process of the MEMS substrate according to the first embodiment.
• FIG. 7 is a longitudinal cross-sectional view illustrating the production process of the MEMS substrate according to the first embodiment.
• FIG. 8 is a longitudinal view of a MEMS substrate according to a second embodiment.
• FIG. 9 is a longitudinal view of a MEMS substrate according to a third embodiment.
• FIG. 10 is a longitudinal cross-sectional view of a MEMS substrate according to a fourth embodiment.
• FIG. 11 is a longitudinal cross-sectional view of a MEMS substrate of a conventional MEMS display device.
• FIG. 12 is a longitudinal cross-sectional view of a MEMS substrate when a shutter adhesion defect occurs.
• FIG. 1 illustrates a display device pertaining to a first embodiment of the present invention.
• FIG. 1(a) is an oblique view of the display device, and (b) is a plan view of the display device.
• the display device 100 pertaining to this embodiment has a MEMS substrate 101 and an aperture plate 109.
• the MEMS substrate 101 is constituted by a display unit 101a, drive circuits 101b, 101c and lOld, and a terminal lOle on a TFT (high-temperature polysilicon) substrate.
• the TFT substrate which constitutes the MEMS substrate 101 and the aperture 109 are connected using bumps and a seal members (not illustrated).
• FIG. 2 is a circuit block diagram of the display device pertaining to an embodiment of the present invention.
• an image signal and a control signal are supplied from a controller 121.
• backlights of the primary colors red (R), green (G) and blue (B) are supplied while being periodically switched from the backlight unit 122 controlled by the controller 121.
• the display device 100 of the present invention does not have to be constituted so as to contain the controller 121 and backlight 122.
• the display unit 101a has pixels 200, which have a mechanical shutter (MEMS shutter) 202, switching element 204 and storage capacitor 206, arranged in a matrix at positions corresponding to the intersections of the gate wires (Gl, G2, ..., Gn) and data wires (Dl, D2, ..., Dm).
• Drive circuits 101b and 101c are data drivers, which supply data signals to the switching element 204 via the data wires (Dl, D2, ..., Dm).
• Drive circuit lOld is a gate driver, which supplies a gate signal to the switching element 204 via the gate wires (Gl, G2, ... Gn). Furthermore, in this embodiment, as shown in FIG.
• drive circuits 101b and 101c which are data drivers are arranged so as to sandwich the display unit 101a, but are not limited to this constitution.
• the switching element 204 drives the MEMS shutter 202 based on the data signals supplied from the data wires (D l, D2, ..., Dm).
• FIG. 3 is an oblique view illustrating the constitution of the MEMS shutter 202 used in the display device 100 pertaining to the first embodiment of the present invention.
• FIG. 3 is an oblique view illustrating the constitution of the MEMS shutter 202 used in the display device 100 pertaining to the first embodiment of the present invention.
• a plurality of MEMS shutters 202 are arranged in a matrix on the TFT substrate that constitutes the MEMS substrate 101.
• the MEMS shutter 202 has a shutter plate 210, first springs 216, 218, 220 and 222, second springs 224, 226, 228 and 230, first anchors 232, 234, 238 and 240, and second anchors 236 and 242.
• a pair of rectangular apertures 212 and 214 are formed, aligned in the short-axis direction with their long axes parallel to each other, and the portions other than the apertures 212 and 214 on the shutter plate 210 (the portions that circumscribe the two apertures 212 and 214, the portion between the aperture 212 and the outer edge adjacent thereto, and the portion adjacent to the aperture 214) are opaque parts having the same width as the apertures 212 and 214.
• an opaque film is formed on the surface of the aperture plate 109, and a plurality of apertures respectively corresponding to each aperture 212 and 214 of each MEMS shutter 202 are formed in this opaque film.
• the MEMS substrate 101 and the aperture plate 109 are mutually positioned such that the apertures 212 and 214 of the shutter plate 210 that has moved to one of the positions and the apertures of the aperture plate 109 substantially overlap in the direction orthogonal to the surface of the TFT substrate 101 e (FIG. 5) which constitutes the MEMS substrate 101.
• backlight which is supplied within the aperture plate 109 and passes through the apertures thereof passes through the apertures 212 and 214 of the shutter plate 210, and is seen by the eye of the viewer.
• first anchors 232 and 234 are connected to first anchors 232 and 234 via a pair of first springs 216 and 218.
• First anchors 232 and 234, together with first springs 216 and 218, have the function of supporting the shutter plate 210 in a state suspended over the surface of the TFT substrate which constitutes the MEMS substrate 101.
• First anchor 232 is electrically connected with first spring 216
• first anchor 234 is electrically connected with first spring 218. Bias potential voltage is applied to first anchors 232 and 234 from the switching element 204 formed on the MEMS substrate 101, and as a result, bias potential voltage is applied to first springs 216 and 218.
• Second springs 224 and 226 are electrically connected to second anchor 236.
• Second anchor 236 has the function of supporting second springs 224 and 226 in a state suspended above the surface of the MEMS substrate 101.
• Second anchor 236 is connected to a ground electrode, and as a result, the potential of second springs 224 and 226 is ground potential. Furthermore, it may also be constituted such that voltage of a prescribed potential is applied to second anchor 236.
• first anchors 238 and 240 The other outer edge parallel to the long-axis direction of the apertures 212 and 214 in the shutter plate 210 are connected to first anchors 238 and 240 via a pair of first springs 220 and 222.
• First anchor 238 is electrically connected with first spring 220
• first anchor 240 is electrically connected with first spring 222.
• Bias potential voltage is applied to first anchors 238 and 240 from the switching element 204 formed on the MEMS substrate 101, and bias potential voltage is applied to first springs 220 and 222.
• Second springs 228 and 230 are electrically connected to second anchor 242.
• Second anchor 242 has the function of supporting second springs 228 and 230 in a state suspended above the surface of the MEMS substrate 101.
• Second anchor 242 is connected to a ground electrode, and as a result, the potential of second springs 228 and 230 is ground potential.
• the display device 100 is capable of a gradient display by controlling the quantity of light that passes through the apertures 212 and 214 based on the position of the shutter plate 210 being varied by being driven at high speed. Further, by sequential driving (field sequential driving) of the three colors R, G and B of light emitted from the backlight unit 122, a color display is also possible. In this case, the polarizing plates and color filters required in a liquid crystal display device become unnecessary, and the light of the backlight can be utilized without being attenuated.
• first springs, second springs, first anchors and second anchors are connected and arranged on both sides of the shutter plate 210
• the display device 100 of the present invention is not limited to this constitution.
• it may also be configured such that first springs, second springs, first anchors and second anchors are connected and arranged on one side of the shutter plate 210, and only the first springs and first anchors are connected and arranged on the other side of the shutter plate 210, and the first springs and first anchors on the other side have the function of supporting the shutter plate 210 in a state suspended above the substrate, and the first springs and second springs on the one side of the shutter plate 210 are electrostatically driven, and the shutter plate 210 is thereby operated.
• FIG. 4 is a plan view of a MEMS substrate 101 in the vicinity of the MEMS shutter 202 according to the first embodiment (however, illustration of the second springs 224, 226, 228 and 230 and second anchors 236 and 242 are omitted).
• FIG. 5 is a longitudinal cross-sectional view along line V-V of FIG. 4.
• a plurality of wires (metal layer) 243 for applying voltage (or connecting a ground electrode) to the anchors 232, 234, 236, 238, 240 and 242 which constitute each MEMS shutter 202 are laid on the surface of the TFT substrate 101 e which constitutes the MEMS substrate 101 (the face near the MEMS shutter 202). Also, part of the wiring (metal layer) 243 overlaps the first springs 216, 218, 220 and 222 and the shutter plate 210 in a direction orthogonal to the surface of the TFT substrate 101 e. [0030]
• An insulating film 244 is formed on the entire surface of the TFT substrate 10 le except the locations where the anchors 232, 234, 236, 238, 240 and 242 are formed.
• the insulating film also covers the wiring (metal layer) 243 in the locations where the wiring (metal layer) 243 is formed.
• the material of the insulating film 244 may be any substance, either organic or inorganic, provided that it is insulating. Examples of inorganic substances are SiO and SiN, and an example of an organic substance is resist.
• the total thickness of the wiring (metal layer) 243 and insulating film 244 is depicted in FIG. 5 so as to occupy half of the gap between the TFT substrate 10 le and the shutter plate 210, but actually, since it is thinner than the gap between the two (4 ⁇ ), it does not interfere with operation of the shutter plate 210.
• FIG. 6 and FIG. 7 illustrate the structure of the same cross-section as FIG. 5 (cross-section along line V-V in FIG. 4) during the course of the formation process.
• FIG. 6 is a cross-sectional view illustrating the state where the wiring 243 has been formed from the metal layer in this manner.
• the insulating film 244 is formed by CVD (chemical vapor deposition) so as to cover the surface of the TFT substrate 101 e including the wiring 243, and by etching using photolithography, a contact hole 244a is formed for forming each of the anchors 232, 234, 236, 238, 240 and 242.
• FIG. 7 is a cross-sectional view illustrating the state where the insulating film 244 has been opened to form the contact hole 244a.
• FIG. 5 is a cross-sectional view illustrating the state where the first anchor 24, first spring 222 and the shutter plate 210 have been formed in this manner.
• first spring 222 and the shutter plate 210 At this time, charging occurs in first spring 222 and the shutter plate 210 due to the effect of static electricity during these processes, and it causes an electrostatic force between them and the TFT substrate 101 e, and first spring 222 and the shutter plate 210 are attracted to the TFT substrate 10 le, and eventually contact the wiring 243.
• the entire wiring 243 is covered by the insulating film 244, the intramolecular forces between first spring 222 and shutter plate 210 and the wiring 243 decrease. Therefore, first spring 222 and the shutter plate 210 can be easily restored to the original suspended state without first spring 222, the shutter plate 210 and the wiring 243 adhering to each other.
• the first anchors 232, 234, 236, 238, 240 and 242 the first springs 216, 218, 220 and 222, and the entire shutter plate 210 are covered with insulating film, thereby completing them.
• second springs 224, 226, 228 and 230 and second anchors 236 and 242 are also simultaneously formed in the above-described process.
• the switching element 244 or ground electrode which constitutes each pixel of the display unit 101a is connected to each wire 244 and the peripheral circuits 101a through 101 d, 121 and 122 are connected to it, thereby completing the MEMS substrate 101.
• a separately -created aperture substrate 109 is connected to the MEMS substrate 101 via bumps and seal members (not illustrated), and the gap between them is filled with silicone oil, and the backlight unit 122 is mounted on the glass substrate of the aperture substrate 109, thereby completing the MEMS display device 100.
• FIG. 8 is a longitudinal view (view illustrating a longitudinal cross-section along line V-V of FIG. 4) of a MEMS substrate in the MEMS display device 100 according to a second embodiment.
• the second embodiment differs from the above-described first embodiment only in the configuration of the insulating film 244, and is otherwise the same. Therefore, descriptions of the constitution other than the insulating film 244 are omitted here, and the above-described first embodiment is to be referenced.
• the insulating film 244 in this embodiment completely prevents exposure of the wiring 243 because it covers the surface and sidewalls of the wiring 243, but it is removed in locations other than that. For this reason, the same effect of preventing adhesion as the first embodiment is obtained, and at the same time, an effect is obtained whereby loss of light is prevented by the absence of insulating film 244 on the path by which the light that was supplied to the aperture plate 109 and passed through the aperture thereof and the apertures 212 and 214 of the shutter plate 210 is transmitted.
• FIG. 9 is a longitudinal view (view illustrating a longitudinal cross-section along line V-V of FIG. 4) of a MEMS substrate in the MEMS device 100 according to a third embodiment.
• the third embodiment differs from the above-described first embodiment only in the
• the insulating film 244 in this embodiment covers the surface and sidewalls of the wiring 243, but is removed in locations other than that. Additionally, the insulating film 244 in this embodiment is also removed from the top of the wiring 243 in locations where first spring 222 and the shutter plate 210 do not overlap in the direction orthogonal to the surface of the TFT substrate lOle. As a result, the wiring 243 is partially exposed, but since the portion exposed on the surface of the wiring 243 does not contact first spring 222 and the shutter plate 210, the wiring 243 does not adhere to first spring 222 and the shutter plate 210, and, similar to the second embodiment, light loss can be prevented.
• FIG. 10 is a longitudinal cross-sectional view (view illustrating a longitudinal cross-section along line V-V of FIG. 4) of a MEMS substrate in the MEMS display device 100 according to a fourth embodiment.
• the fourth embodiment differs from the above-described first embodiment only in the configuration of the insulating film 244, and is otherwise the same. Therefore, descriptions of the constitution other than the insulating film 244 are omitted here, and the above-described first embodiment is to be referenced.
• the insulating film 244 in this embodiment covers the surface of the wiring 243, but is removed in locations other than that. Additionally, the insulating film 244 in this embodiment is also removed from the sidewalls of the wiring 243. As a result, the wiring 243 is exposed on its sidewalls, but since the sidewalls of the wiring 243 do not contact first spring 222 and the shutter plate 210, the wiring 243 does not adhere to first spring 222 and the shutter plate 210, and therefore, the problem of adhesion defects occurring as in the past does not occur. Also, by this
• light loss can be prevented, similar to the second embodiment.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Mechanical Light Control Or Optical Switches (AREA)
• Micromachines (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

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Citations (3)

• 2013
  • 2013-03-18 JP JP2013055451A patent/JP2014182211A/ja active Pending
• 2014
  • 2014-03-17 TW TW103109981A patent/TW201443478A/zh unknown
  • 2014-03-17 WO PCT/US2014/030168 patent/WO2014153281A1/en active Application Filing

Patent Citations (3)

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