Pressure sensor and method for fabricating the same
View Patent ↗A pressure sensor comprising a plurality of sensor parts arranged in matrix. A first electrode being connected with first wiring and a second electrode being connected with second wiring are disposed oppositely through a cavity part in the sensor part. The second electrode bends to the first electrode side in response to a pressure from a specimen and touches the first electrode upon application of a pressure of a specified level or above. When the specimen is pressed against a pressure detecting region, both electrodes touch each other at a sensor part corresponding to a protrusions of the specimen and are separated at a sensor part corresponding to a recess. When a scanning signal is fed from a scanning circuit to one wiring and presence of a signal flowing through the second wiring is detected by a sensing circuit, a pressure being applied to each sensor part can be detected. Furthermore, the shape is detected by feeding the scanning signal from the scanning circuit to each first wiring sequentially and scanning the pressure detecting region generally.
1. A pressure sensor comprising plural sensor sections arranged in a matrix, wherein
each of the sensor sections includes:
a first electrode disposed in a sensor section;
a first insulating film covering the first electrode;
a sensor hole formed in the first insulating film and, also, exposing part of the first electrode;
a cavity located at least above the sensor hole and a portion surrounding it; and
a second electrode disposed opposite to the first electrode with the cavity interposed therebetween and capable of being curved to the first electrode side;
wherein the first electrode comprises:
a central portion located at about the center of the sensor section; and
an annular portion located in the sensor section and that encloses the central portion.
2. The pressure sensor according to claim 1 , wherein
the first insulating film has at least one recess on the first electrode in addition to a sensor hole thereon.
3. The pressure sensor according to claim 1 , wherein
an end edge of the first insulating film is located at the periphery of the first electrode.
4. The pressure sensor according to claim 1 , wherein
a thickness of the first insulating film present at the periphery of the sensor hole is in the range of about 2000 to about 5000 angstroms.
5. The pressure sensor according to claim 1 , wherein
the sensor hole is in the shape of a circle and a diameter thereof is in the range of about 5 to about 40 μm.
6. The pressure sensor according to claim 1 , wherein
the end edge of the first insulating film rising from a surface of the first electrode located below the cavity is inclined to the first electrode.
7. The pressure sensor according to claim 1 , wherein
release holes are disposed in the second electrode so as to correspond to a peripheral portion of the first electrode.
8. The pressure sensor according to claim 1 , wherein
a second insulating film is stacked on the second electrode, and the second insulating film in the vicinity of a center of the sensor section is removed to form an opening.
9. The pressure sensor according to claim 8 , wherein
the removed portion of the second insulating film in the sensor section is in the shape of a circle and a diameter thereof is in the range of about 24 to about 28 μm.
10. The pressure sensor according to claim 8 , wherein
an overcoat film is formed on the second electrode in the opening.
11. The pressure sensor according to claim 10 , wherein
the overcoat film is made of a material different from that of the second insulating film.
12. The pressure sensor according to claim 10 , wherein
the second insulating film is formed with an inorganic insulating film, and the overcoat film is formed with an organic insulating film.
13. The pressure sensor according to claim 10 , wherein
the surface of the overcoat film in the center of the sensor section is flat.