JP3355877B2 - Physical quantity sensor, input device and torque 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 dynamic quantity sensor, an input device and a torque sensor to which a strain resistance element provided on a high strength insulating layer is applied.

[0002]

2. Description of the Related Art In recent years, a pointing device has been proposed as a GUI (graphical user interface) operation input device for a personal computer or the like instead of a mouse or a trackball. In this pointing device, for example, as disclosed in JP-A-5-18702, a movable lever, a thin plate supporting the movable lever, and a holding portion supporting the thin plate are integrally formed from a silicon substrate. There is also known a method in which the displacement of the movable lever is detected by a change in the resistance value of a piezoresistive element formed in a thin plate portion.

Further, a movable lever and a thin plate supporting the movable lever are formed of ceramics such as Al ₂ O ₃ ,
A thick film resistor is printed and fired on the thin plate portion made of ceramics such as Al ₂ O ₃ , and is fixed and held. The displacement of the movable lever changes the resistance value of the thick film resistor formed on the thin plate portion. What detects by change is known.

A movable lever and a stainless steel enameled thin plate supporting the movable lever are formed. A thick film resistor is printed and fired on the stainless enameled thin plate, and is fixed and held. Is known in which the displacement of the thick film resistor formed on the thin plate portion is detected by a change in the resistance value.

[0005]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Laid-Open No. 5-1
In the pointing device disclosed in Japanese Patent No. 8702, since the thin plate portion and the holding portion supporting the thin plate portion are formed of a silicon substrate, the gauge factor (GF) = the rate of resistance change (ΔR / R) / strain (ε). Although it is large, it is basically extremely weak against the operation of the movable lever and the impact force due to a strong force, and a stopper for avoiding a strong force is required.
Therefore, there has been a problem that not only the price increase due to these stoppers accompanies, but also a complicated adjustment process for managing the gap between the stopper and the movable lever is required.

The movable lever and the thin plate supporting the movable lever are formed of ceramics such as Al ₂ O _3.
A pointing device of the type in which a thick-film resistor is printed and fired on a thin plate portion made of ceramics such as ₂ O ₃ has a smaller GF than the above-mentioned pointing device using a silicon substrate, but has a smaller sensor signal noise. There are fewer advantages. However, similarly to the above-described pointing device using a silicon substrate, it is extremely weak in operation of a movable lever by a strong force and an impact force. Therefore, there has been a problem that the same countermeasure is required when a similar price increase occurs.

A pointing device of a type formed of a movable lever and a stainless steel enamel thin plate supporting the movable lever, on which a thick film resistor is printed and fired on the stainless enamel thin plate, is provided by the above two types. Although it is inferior to the GF and the noise of the sensor signal as compared with the pointing device, it is somewhat advantageous in strength.

However, there is a problem that it is difficult to guarantee the strength so that a stopper for avoiding a strong force becomes unnecessary.

The present invention solves the above-mentioned conventional problems, and has an extremely inexpensive and simple structure, while being able to guarantee strength and at the same time sufficiently satisfying basic performance (good GF and low noise of sensor signal). It is an object of the present invention to provide a dynamic quantity sensor, an input device, and a torque sensor.

[0010]

In order to achieve this object, a physical quantity sensor, an input device and a torque sensor according to the present invention are provided.
A compressive stress consisting of glass, ceramics and a reaction product of the glass and ceramics is applied to a desired portion of the surface of the substrate via an oxide film on a surface of a deformable substrate made of an iron alloy containing 10 to 30% by weight of chromium. Is provided, a strain resistance element baked on the surface of the insulation layer, and a conductor provided so as to be connected to the strain resistance element, and a resistance value of the strain resistance element according to deformation of the base. It is characterized by having electrical means for detecting as a change.

[0011]

According to this structure, the oxide film on the surface of the deformable substrate made of an iron alloy containing 10 to 30% by weight of chromium has high strength and denseness while having irregularities.
The bonding strength with the insulating layer formed thereon becomes extremely strong. This is because when the glass forming the insulating layer melts,
Al ₂ O ₃ by the glass at the same time as the anchor effect of the irregularities of the oxide coating is expected wets the surface of the oxide film
Densification proceeds by a mechanism similar to liquid phase sintering of ceramics. Further, a reaction product is generated between the glass and the oxide film, and a stronger bonding strength can be obtained. In the main insulating layer, as the glass melts and wets the surface of the ceramic, the densification progresses by a mechanism similar to the liquid phase sintering of ceramics, and at the same time, a reaction product is created between the liquid phase of the glass and the ceramics. In addition to obtaining a strong bond, when the insulating layer is cooled after firing, a compressive stress due to a difference in thermal expansion between the insulating layer and the base is applied, so that a remarkable improvement in strength is achieved.

Accordingly, a good GF which can not be obtained only on a ceramic substrate, a low noise of a sensor signal, and a characteristic having remarkably high strength which cannot be obtained with a ceramic substrate can be obtained.

[0013]

Embodiment (Embodiment 1) Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the first embodiment, a pointing device will be described as an example of a physical quantity sensor. FIG. 1 is a partial cross-sectional view illustrating a substrate having an insulating layer formed on the surface via an oxide film, which is a main structure of a pointing device according to a first embodiment of the present invention.

In FIG. 1, 1 is a deformable substrate having a thickness of 0.4 mm, 2 is an oxide film formed on the surface of the substrate,
Reference numeral 3 denotes an insulating layer having a thickness of 0.05 mm. 3a is a ceramic in the insulating layer, 3b is a glass in the insulating layer, and 3c is a reaction product in the insulating layer.

In this embodiment, the combinations of the substrate 1 (but before the oxidation treatment) and the starting materials of the insulating layer 3 (however, binder, solvent, plasticizer, etc. are not specified) are shown in (Table 1). Seven types of samples were studied. The rare earths in (Table 1) are cerium, yttrium, lanthanum, neodymium,
It is the sum of praseodymium and the like.

[0016]

[Table 1]

First, the substrate 1 described in Table 1 was heated at 850 ° C.
The oxide film 2 is formed on the surface of the substrate 1 by firing. Then, after the screen printing <br/> on the respective combinations of the starting material of the insulating layer 3 that describes in (Table 1) of the oxide film 2, and baked at 850 ° C.. Table 2 shows the results of measuring the breaking strength of the insulating layer 3 formed on the base 1 while monitoring the breaking strength with a strain gauge. (Table 2) shows SUS43
For comparison, a glass enamel with a conventional glass enamel formed thereon (Comparative Example 1) and a 96% Al ₂ O ₃ ceramic (Comparative Example 2) are also shown for comparison. Regarding the breaking strength, Comparative Example 1
Is expressed as a relative comparison value when 100 is assumed.

[0018]

[Table 2]

[0019] Samples 1 and 2 together, as a reaction product. 3c in the insulating layer 3, CaAl ₂ Si ₂ O ₈ and Ca _0.15 Z
Since r _0.85 O _1.85 is formed, not only a strong bond is obtained between the glass and the ceramic, but also, when the insulating layer is cooled after firing, a compressive stress due to a difference in thermal expansion with the substrate is given, A remarkable improvement in strength is achieved as compared with Comparative Examples 1 and 2. However, the reason why the breaking strength of the sample 1 is lower than that of the sample 2 is considered as follows. In Sample 2, a dense and uneven aluminum oxide film mainly composed of Al ₂ O ₃ is formed as the oxide film 2, and when the glass is melted, an anchor effect of the unevenness of the oxide film can be expected. As the glass wets the surface of the oxide film, densification proceeds by a mechanism similar to liquid phase sintering of Al ₂ O ₃ ceramics. Further, the glass and the oxide film react during firing to form CaAl ₂ Si ₂ O ₈ , and a strong bond is obtained. However, in the sample 1, since an iron oxide or a chromium oxide mainly composed of Cr ₂ O ₃ is formed as the oxide film 2, a positive reaction bond with the glass cannot be obtained. Therefore, it is estimated that the breaking strength of the sample 1 is lower than that of the sample 2.

In sample 3, CaAl ₂ Si ₂ O _8, which is strong over the entire area, is formed as a reaction product 3c in the insulating layer 3.
It is considered that the strength breakage was larger than that of the sample 2 because only the sample was formed.

It is considered that the reason why the strength destruction increases sequentially with samples 4 and 5 as compared with sample 3 is that the adhesion strength of aluminum oxide coating 2 mainly made of Al ₂ O ₃ to substrate 1 is large. Can be Sample 6 is the most preferable combination in terms of the adhesion strength of the aluminum oxide coating 2 to the substrate 1.

Sample 7 is preferable in that the adhesion strength of the oxide film 2 to the substrate 1 is large, but as with the sample 2, the reaction product 3c in the insulating layer 3 is not only CaAl ₂ Si ₂ O ₈ but also Ca _0.15. The breaking strength is slightly reduced by the amount of Zr _0.85 O _1.85 .

FIG. 2 is a schematic perspective view of a pointing device using the base 1 having the insulating layer 3 formed on the surface via the oxide film 2 described in FIG. In FIG. 2, a substrate 1 having an insulating layer 3 formed on the surface thereof via an oxide film 2 (not shown) [sample 6 which is the most preferable combination from the results of (Table 1) and (Table 2) is adopted], Reference numeral 4 denotes an operation unit, 5 denotes a mounting table, 6 denotes a spacer, 7 denotes a fixing unit, 8, 9, 10, and 11 denote RuO ₂ -based strain resistance elements formed by printing and firing.
2 is a silver-palladium-based conductor, 13 is a power supply terminal, 1
4a and 14b are output voltage terminals, and 15 is a ground terminal. The operation unit 4 is connected to the base 1, and is fixed to the mounting table 5 at two locations by a fixing unit 7 via a spacer 6. The strain resistance elements 8 and 9 are formed in deformed portions of the base 1, and the strain resistance elements 10 and 11 are formed in non-deformed portions, forming a bridge. Therefore, when a force is applied to the operation unit 4 by a finger, the resistance values of the strain resistance elements 8 and 9 change. Therefore, the operation unit 4 must be connected to electrical means (not shown) for detection via the output voltage terminals 14a and 14b. Thus, the direction and magnitude of the force applied to the operation unit 4 can be detected. Further, the operation unit 4
Even if an excessive input of 3 kgf is applied, the performance can be assured without destruction. Therefore, a stopper is not particularly required to regulate the operation unit 4. Therefore, not only can the cost of the member corresponding to the stopper be reduced, but also there is no occurrence of an adjustment step between the operation unit 4 and the stopper.

In this embodiment, when the oxide film 2 is formed on the surface of the substrate by firing the substrate 1 at 850 ° C., and the starting material of the insulating layer 3 is screen-printed on the oxide film 2, Although only the case of firing at 850 ° C. has been described, this method is not necessarily limited to this temperature. Further, it is not always necessary to oxidize the surface of the base before printing and firing the insulating layer 3, and the surface of the base may be oxidized during firing of the insulating layer 3, resulting in the formation of the oxide film 2. Absent.

In the present embodiment, only the element formed at the deformed portion at two strain resistance elements has been described, but the element formed at the deformed portion at four locations may be used.

In this embodiment, the insulating layer 3 contains Al ₂
Since there are a ceramic 3a made of O ₃ and a reaction product 3c made of CaAl ₂ Si ₂ O ₈ , the GF (18 or more) and the noise level of the sensor signal (measured by a current noise meter: 0)
dB or less) also shows characteristics relatively close to those formed with thick film resistors on ceramics such as Al ₂ O ₃ . In the present embodiment, a rutile RuO ₂ -based strain resistive element has been described. However, in order to further reduce noise (-3 dB or less), a pyrochlore-type Pb ₂ Ru ₂ O ₆ , B
It is also possible to appropriately mix i ₂ Ru ₂ O ₇ , (Bi, Pb) ₂ Ru ₂ O _{7 and the} like. The conductor has been described using a silver-palladium system, but various conductors such as a silver-platinum system and a copper system can be used.

Embodiment 2 Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. In the second embodiment, as the physical quantity sensor,
A description will be given of a torque sensor as an example. FIG. 3 is a schematic perspective view of a torque sensor using the base 1 having the insulating layer 3 formed on the surface via the oxide film 2 described in the first embodiment. here,
The same parts as those in the first embodiment are denoted by the same reference numerals.
In FIG. 3, a substrate 1 having an insulating layer 3 formed on the surface thereof via an oxide film 2 (not shown) [Table 1 of Example 1,
Sample 6 which is the most preferable combination from the results of (Table 2) is adopted], 7 is a fixed part, 12 is a silver-palladium-based conductor,
13 is a power supply terminal, 14a and 14b are output voltage terminals,
Reference numeral 15 denotes a ground terminal, 16 denotes a shaft made of 25 mm square carbon steel for mechanical structure, and 17, 18, 19, and 20 denote RuO ₂ -based strain resistance elements formed by printing and firing. Base 1
Are fixed to the shaft 16 at four positions by fixing portions 7. Also,
The strain resistance elements 17 and 18 are +4 with respect to the longitudinal direction of the shaft 16.
The strain resistance elements 19 and 20 are formed in a direction forming −45 ° with respect to the longitudinal direction of the shaft 16 to form a bridge. Therefore, when torque is applied to the shaft 16, the resistance values of the strain resistance elements 17, 18, 19, and 20 change. Therefore, it is necessary to connect to the electric means (not shown) for detection via the output voltage terminals 14a and 14b. Thus, the direction and magnitude of the torque applied to the shaft 16 can be detected.

Further, even if an excessive torque of ± 15 kgfm is applied to the shaft 16, the shaft 16 is not broken and the initial performance can be guaranteed.

In this embodiment, only the structure in which the strain resistance element is formed at four positions has been described. Of course, it may be provided. Further, the direction in which the strain resistance elements are formed is not necessarily limited to ± 45 °, and it is sufficient that the elements are preferentially oriented.

As for the method of fixing the base to the shaft, only the method of fixing at two locations at both ends has been described, but the present invention is not limited to this. Also, only the configuration in which the plate-shaped base and the axis of the square cross section are provided separately from each other has been described,
It is not necessarily limited to this. For example, a method of fixing a plate-shaped substrate on a plane parallel to the axial direction of the axis of the D-cut cross section, or an oxide coating, an insulating layer, a strain resistance element, and a conductor directly on the plane parallel to the axial direction of the axis of the D-cut cross section , Terminals, etc., and various other configurations are conceivable.

As in the case of the first embodiment, A
ceramics 3a made of l ₂ O ₃ or CaAl ₂ Si ₂ O ₈
Because of the presence of the reaction product 3c, the noise level of the GF and the sensor signal also exhibits characteristics relatively close to those formed by thick film resistors on ceramics such as Al ₂ O ₃ . Similarly, in the present embodiment, a rutile RuO-type
_{Although the} description has been made with respect to the system ₂ , pyrochlore type Pb ₂ Ru ₂ O ₆ and Bi ₂ Ru ₂ are used in order to further reduce noise.
A mixture of O ₇ , (Bi, Pb) ₂ Ru ₂ O _{7 and the} like is also possible. The conductor has been described using silver-palladium, but various conductors such as silver-platinum and copper can be used.

In the above-described first and second embodiments, the description has been made only for the input device such as the pointing device and the torque sensor. However, the same configuration can be widely applied to other mechanical quantity sensors.

[0033]

As described above, according to the present invention, chromium 10 to 3
Insulation in which a compressive stress consisting of glass, ceramics, and a reaction product of glass and ceramics is applied to a desired portion of the substrate surface via an oxide film on a surface of a deformable substrate made of an iron alloy containing 0% by weight. With a simple structure including a layer and a strain-resisting element fired on the surface of this insulating layer, good GF, which can be obtained only on a ceramic-based substrate in the past, low sensor signal noise, It is possible to provide a dynamic quantity sensor, an input device, and a torque sensor having both sides of remarkable strength that cannot be obtained.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view illustrating a substrate having an insulating layer formed on the surface via an oxide film, which is a main structure of a pointing device according to a first embodiment of the present invention.

FIG. 2 is a schematic perspective view of a pointing device using a substrate having an insulating layer formed on the surface via an oxide film in the first embodiment of the present invention.

FIG. 3 is a schematic perspective view of a torque sensor using a substrate having an insulating layer formed on the surface via an oxide film according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Oxide film 3 Insulating layer 3a Ceramics 3b Glass 3c Reaction product 4 Operation part 5 Mounting base 6 Spacer 7 Fixed part 8 Strain resistance element 9 Strain resistance element 10 Strain resistance element 11 Strain resistance element 12 Conductor 13 Power supply terminal 14a output voltage terminal 14b output voltage terminal 15 ground terminal 16 axis 17 distortion resistance element 18 distortion resistance element 19 distortion resistance element 20 distortion resistance element

──────────────────────────────────────────────────の Continuing on the front page (51) Int.Cl. ⁷ Identification symbol FI H05B 3/84 H05B 3/20 355A (72) Inventor Yukio Mizukami 1006 Ojidoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 72) Inventor Makoto Kamei 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-7-167720 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , (DB name) G01L 1/22 G01B 7/16 G06F 3/033 330 H01L 29/84

Claims (12)

(57) [Claims] 1. Deformation of glass, ceramics, and reaction of glass and ceramics on a desired portion of the surface of a deformable substrate made of an iron alloy containing 10 to 30% by weight of chromium through an oxide coating on the surface of the substrate. An insulating layer to which a compressive stress made of a material is applied; a strain resistance element baked on the surface of the insulation layer; and a conductor provided so as to be connected to the strain resistance element. A dynamic quantity sensor having an electrical means for detecting a change in resistance value of a resistance element. 2. The substrate according to claim 1, wherein the substrate is an iron alloy containing 10 to 30% by weight of chromium and 0.05 to 7% by weight of aluminum.
The physical quantity sensor as described. 3. The physical quantity sensor according to claim 1, wherein the substrate is an iron alloy containing 10 to 30% by weight of chromium, 0.05 to 7% by weight of aluminum, and 0.1 to 5% by weight of titanium. 4. A substrate comprising 10 to 30% by weight of chromium, 0.05 to 7% by weight of aluminum, cerium, yttrium,
The sum of lanthanum, neodymium, and praseodymium is 0.0
The physical quantity sensor according to claim 1, wherein the physical quantity sensor is an iron alloy containing 6 to 0.12% by weight. 5. The physical quantity sensor according to claim 1, wherein the oxide coating mainly comprises at least one of iron oxide, chromium oxide, and aluminum oxide. 6. The ceramic according to claim 1, wherein the ceramic is made of at least one of Al ₂ O _{3 and} CaZrO ₃ .
The dynamic quantity sensor according to any one of 3, 4, and 5. 7. The reaction product has at least CaAl ₂ S
dynamic quantity sensor according to any of claims 1,2,3,4,5,6 consisting of either i ₂ O ₈ or Ca _0.15 Zr _0.85 O _1.85. 8. The total of 15 to 26% by weight of chromium, 2 to 7% by weight of aluminum, cerium, yttrium, lanthanum, neodymium and praseodymium is 0.06 to 0.12.
On the surface of a deformable substrate made of an iron alloy containing
Glass, Al ₂ O ₃ ceramics, CaAl ₂ are applied to a desired portion of the substrate surface mainly through an aluminum oxide film.
An insulating layer provided with a compressive stress made of a reaction product of Si ₂ O _8, a strain resistance element fired on the surface of the insulation layer, and a conductor provided to be connected to the strain resistance element; A physical quantity sensor comprising electrical means for detecting a change in the resistance value of the strain resistance element according to deformation. 9. A total of 0.06 to 0.12 of 15 to 26% by weight of chromium, 2 to 7% by weight of aluminum, cerium, yttrium, lanthanum, neodymium, and praseodymium.
On the surface of a deformable substrate made of an iron alloy containing
Glass, ceramics in which Al ₂ O ₃ and CaZrO ₃ are mixed, CaAl ₂ Si ₂ O ₈ and Ca _0.15 Zr mainly at a desired portion of the substrate surface via an aluminum oxide film
_0.85 O _1.85 and an insulating layer to which a compressive stress composed of a reaction product mixed with the strain-resistant element fired on the surface of the insulating layer and a conductor provided to be connected to the strain-resistant element are provided. A physical quantity sensor comprising electrical means for detecting a change in the resistance value of the strain resistance element according to the deformation of the base. 10. Chromium 15-26% by weight, Aluminum 2-7% by weight, cerium, yttrium, lanthanum,
The sum of neodymium and praseodymium is 0.06-0.1
On a surface of a deformable substrate made of an iron alloy containing 2% by weight, glass and at least Al ₂ O ₃ or Ca are applied to a desired portion of the substrate surface mainly through an aluminum oxide coating.
An insulating layer to which a compressive stress is applied, which is made of a ceramic made of any one of ZrO _{3 and} a reaction product made of at least one of CaAl ₂ Si ₂ O ₈ or Ca _0.15 Zr _0.85 O _1.85 ; At least two
Two strain resistance elements and a conductor provided so as to be connected to the strain resistance element are provided, and an operating part set up at the center of the base and at least two fixing parts around the base are provided, An input device comprising: an electrical unit for detecting a force and a direction applied to an operation unit by a change in a resistance value of a strain resistance element. 11. A rotatably supported shaft, a deformable substrate made of an iron alloy containing 10 to 30% by weight of chromium provided on a part of the shaft, and an oxide coating on the surface of the substrate. A glass provided on a desired portion of the substrate surface,
A ceramic and an insulating layer to which a compressive stress made of a reaction product of the glass and the ceramic is applied, and preferentially in a direction forming 45 ° and −45 ° with respect to a longitudinal direction of the shaft fired on the surface of the insulating layer. And a conductor provided so as to be connected to the strain resistance element, and electrical means for detecting as a change in resistance value of the strain resistance element according to deformation due to torque transmitted to the shaft. A torque sensor, comprising: 12. A total of 0 to 26% by weight of chromium, 2 to 7% by weight of aluminum, cerium, yttrium, lanthanum, neodymium, and praseodymium provided on a rotatably supported shaft and a part of the shaft is provided. 0.06-0.12
A deformable substrate made of an iron alloy containing 0.1% by weight, a glass provided on a desired portion of the substrate surface mainly through an aluminum oxide coating on the substrate surface, and at least Al ₂ O ₃
Or a ceramic made of either CaZrO ₃ and at least CaAl ₂ Si ₂ O ₈ or Ca _0.15 Zr _0.85
O.85 , the insulating layer to which a compressive stress is applied consisting of a reaction product consisting of any one of O _1.85 and a direction which forms 45 ° and −45 ° with respect to the longitudinal direction of the shaft fired on the surface of the insulating layer. Electrical means comprising: a strain-resistor element oriented in a predetermined direction; and a conductor provided so as to be connected to the strain-resistor element, and detecting as a change in resistance value of the strain-resistor element in accordance with deformation due to torque transmitted to the shaft. A torque sensor comprising: