JPH0749272A - Electrostatic capacity type force sensor - Google Patents

Abstract

PURPOSE:To provide an electrostatic capacity type force sensor manufactured at a low cost and excellent in mass productivity by dispensing with an FPC needed in a conventional force sensor and a distortional metal body in need of precision cutting. CONSTITUTION:A sensor part 1 is formed of an electrode plate 5 to be a common electrode C provided at the lower end of an input shaft 4, and electrode parts 6a, 6b to be electrodes Cx<+>, Cx<-> disposed from the lateral and longitudinal directions so as to be opposed to the electrode plate 5 while having a gap G. This sensor part 1 is made into a package by a mold 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitance type force sensor that can be used as a cursor movement operation unit (pointing device) of a computer.

[0002]

2. Description of the Related Art As a conventional force sensor, for example, FIG.
There are those shown in 1 and 12. This force sensor includes, as shown in the figure, a single crystal substrate 20 having at least four detection elements whose electric resistance is changed by mechanical deformation,
It has a plate-shaped body 90 having a diaphragm portion 91 in the central portion,
It comprises a metal strain element 94 having a shaft portion 92 protruding from the center of the bottom surface of the diaphragm portion 91, and the single crystal substrate 20 is stretched over the center portion of the upper surface of the dish 90. In the figure, H is a protective material coated on the surface of the single crystal substrate 20 to cover the single crystal substrate 20, and C is a metal cap that further covers the protective material H.

In the conventional force sensor having such a structure, when an external force is applied to the shaft portion 92, the upper surface of the dish 90 and the single crystal substrate 20 are integrally formed according to the magnitude and direction of the external force. It deforms, and the electric resistance of each detection element changes according to the deformation mode of the single crystal substrate 20. Therefore, if the change in the electrical resistance of the detection element is taken as the change in voltage and is taken out through the FPC (Flexible Print Circuit) 93 bonded to the single crystal substrate 20 with the wire W as shown in FIG. The direction and magnitude of the external force acting on 92 can be detected.

[0004]

However, in the above-described conventional force sensor, the detection element must be manufactured by using the semiconductor IC process, and the metal strain element 94 must be precisely cut. Therefore, there are problems that the manufacturing cost is very high and mass productivity is insufficient.

Therefore, the present invention has been made for the purpose of providing a capacitance type force sensor which can be manufactured at low cost and is excellent in mass productivity.

[0006]

Therefore, according to the capacitance type force sensor of the present invention, the electrode C provided at the lower end of the input shaft 4 is used.
And an electrode plate 5 having a gap G.
Electrodes Cx arranged in the left-right front-back direction so as to face the
+, Cx-, Cy +, and Cy- are the electrode portions 6a, 6b,
The sensor unit 1 including 6c and 6d is packaged by the mold 3.

Further, the capacitance type force sensor of the present invention has an electrode plate 5 serving as an electrode C provided at the lower end of the input shaft 4 and a left and right front and back so as to face the electrode plate 5 with a gap G. The electrodes Cx +, Cx−, Cy +, which are arranged from the direction
The sensor unit 1 including the electrode portions 6a, 6b, 6c, 6d to be Cy- and the electrode portion 6e to be the electrode Cz arranged in the center so as to face the electrode plate 5 is packaged by the mold 3. Can also be

Further, in the capacitance type force sensor of the present invention, the sensor section 1 may be provided with the IC section 2 in parallel, and the IC section 2 may be packaged by the mold 3.

[0009]

Since the capacitance type force sensor of the present invention has the above-mentioned structure, when the input shaft 4 is displaced in the left-right and front-back directions by the fingers or the like, the gap G between the respective electrodes is changed, and the gap G between them is changed. The capacitance changes. as a result,
Since the amount of displacement of the input shaft 4 in the displaced direction can be directly taken out from the lead terminal or the like as a voltage output, the FPC is unnecessary. Further, it becomes unnecessary to use a metal flexure element that requires precise cutting.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of a capacitance type force sensor of the present invention will be described in detail below with reference to the drawings shown as embodiments. FIGS. 1 to 4 show a first embodiment of the present invention, FIGS. 1 to 4 show a second embodiment, FIG. 9 shows a third embodiment, and FIG. Shows a fourth embodiment. In the first to third embodiments, the IC unit 2 is arranged in parallel with the sensor unit 1 and both are packaged by the mold 3. In the fourth embodiment, the IC unit 2
Is a separate body, and only the sensor portion 1 is packaged by the mold 3.

In the first embodiment, the sensor portion 1 has an electrode plate 5 serving as an electrode C provided at the lower end of the input shaft 4 and a left and right front-rear direction (face) so as to face the electrode plate 5 with a gap G. Electrodes Cx + arranged from the (X-X direction, YY direction),
Electrode portions 6a, 6b, 6 serving as Cx−, Cy +, and Cy−
It is composed of c and 6d. Also, the sensor unit 1
In the second to fourth embodiments, is an electrode plate 5 provided on the lower end of the input shaft 4 to serve as an electrode C, and has a gap G so as to face the electrode plate 5 in the left-right front-back direction (XX Direction, Y-
Electrodes Cx +, Cx−, Cy +, C arranged from (Y direction)
It is composed of electrode portions 6a, 6b, 6c and 6d which are y-, and an electrode portion 6e which is an electrode Cz arranged in the center so as to face the electrode plate 5.

In the first and third embodiments, the electrode plate 5 is provided with elastic foot portions 5a on opposite sides thereof, and in the second and fourth embodiments, it is provided on four sides thereof. Elastic foot portions 5a are provided, and these elastic foot portions 5a are provided.
Are connected to the ends of the lead terminals 7 by spot welding or the like. In addition, the electrode portions 6a, 6b, 6
c, 6d, and 6e are formed on the end portions of the lead terminals 7 in the first, second, and fourth embodiments, respectively, and in the third embodiment, as metal plates that are separate from the lead terminals 7. There is.

The IC part 2 has an IC chip 9 on the board mounting part 8.
It is formed by die bonding. The wires W are bonded to the IC chip 9 from the ends of the lead terminals 7 in the first and second embodiments, and in the third embodiment, the ends of the lead terminals 7 and the ends of the metal plate. Wire from part W
Are bonded. The mold 3 is usually a synthetic resin mold made of epoxy resin or the like, but a ceramic mold or the like may be used if necessary.

The form of the package formed by the mold 3 is the DIP (Dual Inline Package) type in the embodiment, but is SOP (Small Outline Package) type, SOJ (Sma).
ll Outline J-lead Package) type, QFP (Quad Flat Pac)
kage) type and other various packages. Also, the electrode C and the electrodes Cx +, Cx−, Cy +, Cy
Any one or both of − and Cz can be coated with an insulating film (not shown) as necessary.

Further, the electrode C and the electrodes Cx +, Cx
The gap G between −, Cy +, Cy−, and Cz may be filled with an elastic member (not shown) such as rubber if necessary. The electrostatic capacity type force sensor of the present invention is equipped with an electronic device (not shown). This electronic device converts the respective capacitances due to the change in the gap G between the electrode C and the respective electrodes Cx +, Cx−, Cy +, Cy−, Cz into voltages Vx +, Vx−, Vy +, Vy−, Vz, respectively. It is supposed to do.

Therefore, the input shaft 2 is moved in the left-right direction (X-X
Voltage Vx when displaced in the (direction) is (Vx +)-(V
x-), the voltage Vy when the input shaft 2 is displaced in the front-back direction (Y-Y direction) is (Vy +)-(Vy-), and the input shaft 2 is displaced in the vertical direction (Z-Z direction). The voltage Vz when the voltage is set is (Vx +) + (Vx −) + (Vy +) + (Vy
-) Or Vz.

[0017]

The capacitance type force sensor of the present invention is configured as described above, and when the input shaft 4 is displaced in the left-right front-back direction and the up-down direction by a finger or the like, each portion between the electrodes is changed. Gap G changes, and the capacitance changes between them. As a result, the amount of displacement of the input shaft 4 in the displaced direction can be directly taken out from the lead terminal or the like as a voltage output. Therefore, the FPC, which was required in the conventional force sensor, becomes unnecessary, and the metal flexure element that requires a precise cutting process is not used, so that it can be manufactured at low cost and has excellent mass productivity. Will be things.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of a capacitance type force sensor of the present invention.

FIG. 2 is a cross-sectional view taken along the line AA in FIG.

FIG. 3 is a perspective view of an input shaft of the capacitance type force sensor of the first embodiment and an electrode plate provided at a lower end thereof.

FIG. 4 is a plan view of the capacitance type force sensor according to the first embodiment, in which a mold, an input shaft, and an electrode plate are omitted.

FIG. 5 is a perspective view showing a second embodiment of the capacitance type force sensor of the present invention.

6 is a sectional view taken along line BB in FIG.

FIG. 7 is a perspective view of an input shaft of an electrostatic capacity type force sensor of a second embodiment and an electrode plate provided at a lower end thereof.

FIG. 8 is a plan view of a capacitance type force sensor according to a second embodiment, in which a mold, an input shaft, and an electrode plate are omitted.

FIG. 9 is a plan view of a capacitance type force sensor according to a third embodiment, in which a mold, an input shaft, and an electrode plate are omitted.

FIG. 10 is a plan view of a capacitance type force sensor according to a fourth embodiment, in which a mold, an input shaft, and an electrode plate are omitted.

FIG. 11 is a sectional view of a conventional force sensor.

FIG. 12 is a perspective view showing a main part of a conventional force sensor.

[Explanation of symbols]

 1 sensor part 2 IC part 3 mold 4 input shaft 5 electrode plate 6a electrode part 6b electrode part 6c electrode part 6d electrode part 6e electrode part C electrode Cx + electrode Cx− electrode Cy + electrode Cy− electrode Cz electrode G gap

Claims (4)

[Claims] 1. An electrode (C) provided at the lower end of an input shaft (4)
And an electrode (5) having a gap (G) and electrodes (Cx +) (Cx−) (Cy +) (Cy−) arranged in the front-rear direction so as to face the electrode plate (5). A capacitive force sensor, characterized in that a sensor section (1) comprising electrode sections (6a) (6b) (6c) (6d) is packaged by a mold (3). 2. An electrode (C) provided at the lower end of the input shaft (4)
And an electrode (5) having a gap (G) and electrodes (Cx +) (Cx−) (Cy +) (Cy−) arranged in the front-rear direction so as to face the electrode plate (5). Electrode portions (6a) (6b) (6c) (6d), and an electrode (C disposed in the center so as to face the electrode plate (5).
z) sensor part (1) consisting of electrode part (6e)
Is a packaged by a mold (3). 3. An electrode (C) provided at the lower end of the input shaft (4)
And an electrode (5) having a gap (G) and electrodes (Cx +) (Cx−) (Cy +) (Cy−) arranged in the front-rear direction so as to face the electrode plate (5). The IC part (2) is arranged in parallel with the sensor part (1) composed of the electrode parts (6a) (6b) (6c) (6d), and both are packaged by the mold (3). Capacitive force sensor. 4. An electrode (C) provided at the lower end of the input shaft (4)
And an electrode (5) having a gap (G) and electrodes (Cx +) (Cx−) (Cy +) (Cy−) arranged in the front-rear direction so as to face the electrode plate (5). Electrode portions (6a) (6b) (6c) (6d), and an electrode (C disposed in the center so as to face the electrode plate (5).
z) sensor part (1) consisting of electrode part (6e)
Then, the IC parts (2) are arranged side by side, and both are molded (3).
Capacitive force sensor characterized by being packaged by.