JP3284251B2 - Capacitive force sensor - Google Patents

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 which can be used as a cursor moving operation section (pointing device) of a computer.

[0002]

2. Description of the Related Art As a conventional force sensor, for example, FIG.
1 and 12 exist. As shown in the figure, the force sensor includes a single crystal substrate 20 having at least four detection elements whose electric resistance changes due to mechanical deformation,
A dish-shaped body 90 having a central portion as a diaphragm portion 91,
A metal strain body 94 having a shaft portion 92 protruding from the center of the bottom surface of the diaphragm portion 91 is provided. The single crystal substrate 20 is stretched at the center of the upper surface of the dish-shaped body 90. In the figure, H is a protective material that is applied to 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 configured as described above, when an external force is applied to the shaft portion 92, the upper surface of the dish-like body 90 and the single crystal substrate 20 are integrally formed according to the magnitude and direction of the external force. The single crystal substrate 20 is deformed, 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 electric resistance of the detection element is taken out as a change in voltage through a FPC (Flexible Print Circuit) 93 bonded to the single crystal substrate 20 with a wire W as shown in FIG. It is possible to detect the direction and magnitude of the external force acting on 92.

[0004]

However, in the above-described conventional force sensor, the detecting element must be manufactured by utilizing a semiconductor IC process, and precise cutting of the metal strain body 94 is required. Therefore, there has been a problem that the manufacturing cost is very high and the mass productivity is lacking.

Therefore, an object of the present invention is to provide a capacitance type force sensor which can be manufactured at low cost and is excellent in mass productivity.

[0006]

According to the first aspect of the present invention, there is provided a capacitance type force sensor having an electrode plate provided at a lower end of an input shaft and serving as an electrode, and a gap. Electrode portions 6 serving as electrodes Cx +, Cx−, Cy +, Cy− arranged in the left-right and front-rear directions so as to face the lever electrode plate 5.
The sensor unit 1 composed of a, 6b, 6c, and 6d is packaged by a mold 3, and in the packaged state, the gap G is spaced from the electrode plate 5 at intervals of 90 ° or 180 ° in plan view. It is maintained by the provided elastic feet 5a, and is maintained in such a manner that the entire periphery of the electrode plate 5 is supported by the mold 3.

The capacitive 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 rear direction having a gap G so as to face the electrode plate 5. The IC part 2 is arranged side by side on the sensor part 1 composed of the electrode parts 6a, 6b, 6c, 6d to be the arranged electrodes Cx +, Cx-, Cy +, Cy-. In the packaged state, the gap G is 9
The electrode plate 5 is maintained by elastic feet 5a provided at 0 ° or 180 ° intervals, and the mold 3
Is maintained in such a manner that the entire circumference of the is supported.

(Embodiment of Claim 3) The capacitive force sensor of the present invention relates to the invention of Claim 1 or 2, and relates to the electrodes Cx +, Cx-, Cy +, C
An electrode portion 6e to be an electrode Cz surrounded by y- is provided. (Invention of Claim 4) The capacitive force sensor of the present invention relates to the invention of Claim 1 or 2, wherein the electrode portions 6a, 6b, 6c, 6d are connected to the lead terminal 7 or the IC portion 2. ing. (Embodiment of Claim 5) The capacitive force sensor according to the present invention relates to the above-mentioned invention of claim 3, wherein the electrode portions 6a, 6b, 6c, 6d, 6e are connected to the lead terminals 7 or the IC portion 2. ing.

[0009]

Since the capacitance type force sensor of the present invention has the above-described structure, when the input shaft 4 is displaced in the left, right, front and rear directions by a finger or the like, the gap G of each part between the electrodes changes, and the gap G between these electrodes changes. The capacitance changes. as a result,
Since the displacement amount of the input shaft 4 in the displaced direction can be directly taken out from a lead terminal or the like as a voltage output, the FPC becomes unnecessary. Further, it is not necessary to use a metal strain body that requires precise cutting.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the construction of a capacitance type force sensor according to the present invention. FIGS. 1 to 4 show a first embodiment, FIGS. 5 to 8 show a second embodiment, FIG. 9 shows a third embodiment, and FIGS. 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
And the sensor part 1 is packaged by the mold 3.

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

In the first and third embodiments, the electrode plate 5 is provided with elastic feet 5a on opposite sides, respectively. In the second and fourth embodiments, the elastic legs 5a are provided on the four sides, respectively. An elastic foot 5a is provided.
Are connected to the ends of the lead terminals 7 by spot welding or the like. Further, the electrode portions 6a, 6b, 6
In the first, second, and fourth embodiments, c, 6d, and 6e are formed at the ends of the lead terminals 7, respectively. In the third embodiment, the metal plates are formed separately from the lead terminals 7. I have.

The IC section 2 includes an IC chip 9
By die bonding. In the first and second embodiments, the wire W is bonded to the IC chip 9 from the end of the lead terminal 7. In the third embodiment, the end of the lead terminal 7 and the end of the metal plate are bonded. Wire W from section
Bonding. The mold 3 is usually a synthetic resin mold made of epoxy resin or the like, but may be a ceramic mold or the like if necessary.

In the embodiment, the form of the package by the mold 3 is a DIP (Dual Inline Package) type, but an SOP (Small Outline Package) type and an SOJ (Sma
ll Outline J-lead Package) type, QFP (Quad Flat Pac)
Various packages such as a kage type are available. Further, the electrode C and the electrodes Cx +, Cx−, Cy +, Cy
-And Cz may be coated with an insulating film (not shown), or any of them, if necessary.

Further, the electrode C and the electrodes Cx +, Cx
The gap G between −, Cy +, Cy−, and Cz may be embedded with an elastic member (not shown) such as rubber as needed. The capacitive force sensor of the present invention includes an electronic device (not shown). This electronic device converts the respective capacitances due to the change of the gap G between the electrode C and the respective electrodes Cx +, Cx−, Cy +, Cy−, Cz into voltages Vx +, Vx−, Vy +, Vy−, Vz, respectively. Shall do.

Therefore, the input shaft 2 is moved in the left-right direction (XX
(Vx +) − (V)
x-), the voltage Vy when the input shaft 2 is displaced in the front-rear direction (Y-Y direction) is (Vy +)-(Vy-), and the input shaft 2 is displaced in the vertical direction (Z-Z direction). The voltage Vz at this time is (Vx +) + (Vx-) + (Vy +) + (Vy
−) Or Vz.

[0017]

The capacitance type force sensor of the present invention is constructed as described above. When the input shaft 4 is displaced in the left-right and front-rear directions and the up-down direction by a finger or the like, each part between the electrodes is displaced. , And the capacitance changes between them. As a result, the displacement amount of the input shaft 4 in the displaced direction can be directly taken out from a lead terminal or the like as a voltage output. Therefore, the FPC required for the conventional force sensor is not required, and a metal strain body that requires precise cutting is not required, so that it can be manufactured at low cost and has excellent mass productivity. It will be.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of a capacitive force sensor according to the present invention.

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

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

FIG. 4 is a plan view of the capacitive 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.

FIG. 6 is a sectional view taken along line BB in FIG. 5;

FIG. 7 is a perspective view of an input shaft of a capacitive force sensor according to 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]

 DESCRIPTION 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

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-148833 (JP, A) JP-A-3-111729 (JP, A) JP-A-4-123465 (JP, A) 102740 (JP, U) Japanese Utility Model Showa 58-106740 (JP, U) Table 2-2-504079 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01L 5/16 G06F 3 / 033

Claims (5)

(57) [Claims] 1. An electrode plate 5 serving as an electrode C provided at a lower end of an input shaft 4, and electrodes Cx + and Cx having a gap G and arranged from left, right, front and rear so as to face the electrode plate 5.
-, Cy +, Cy- electrode portions 6a, 6b, 6c, 6
d is packaged by a mold 3, and in the packaged state, the gap G is formed by elastic feet provided at 90 ° or 180 ° intervals from the electrode plate 5 in plan view. 5. A capacitive force sensor, wherein the force sensor is maintained by 5 a and is maintained in such a manner that the entire periphery of the electrode plate 5 is supported by the mold 3. 2. An electrode plate 5 serving as an electrode C provided at the lower end of the input shaft 4, and electrodes Cx + and Cx having a gap G and arranged in the left-right and front-rear directions so as to face the electrode plate 5.
-, Cy +, Cy- electrode portions 6a, 6b, 6c, 6
The IC part 2 is arranged side by side with the sensor part 1 made of d, and both are packaged by a mold 3.
In the packaged state, the gap G is maintained by the elastic feet 5 a provided at 90 ° or 180 ° intervals in plan view from the electrode plate 5, and the entire periphery of the electrode plate 5 is formed by the mold 3. A capacitive force sensor maintained in a supported manner. 3. The capacitance type force sensor according to claim 1, further comprising an electrode portion 6e which is an electrode Cz surrounded by the electrodes Cx +, Cx−, Cy +, Cy−. . 4. The capacitance type force sensor according to claim 1, wherein the electrode portions are connected to the lead terminals or the IC portion. 5. The capacitive force sensor according to claim 3, wherein the electrode portions are connected to the lead terminals or the IC portion.