JPH0663889B2 - Distributed pressure sensor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a distributed pressure sensor, and more specifically, to a force applied to a surface of a robot hand or the like when the robot hand or the like grips an object. The present invention relates to a distributed pressure sensor capable of detecting a distribution.

[Conventional technology]

A conventional distributed pressure sensor that attaches to a robot hand, etc., and detects the distribution of force applied in the vertical direction to the hand, using a conductive rubber or plastic as the detection element, or a Hall element facing a magnet. There is known a device which is provided at a position and detects a change in the magnetic flux density due to the displacement of the hall element when a vertical force is applied to the sensor head holding the hall element.

However, a sensor using conductive rubber or the like has the drawback that the sensor output becomes non-linear and the wiring density increases when trying to detect the force distribution with high density. The conventional ones have drawbacks that it is difficult to miniaturize them due to their complicated structure and that the output sensitivity varies depending on whether the grasped object is a magnetic substance or a non-magnetic substance.

By the way, in recent years, the development of a distributed pressure sensor that is attached to a robot hand or the like and can obtain the information of the surface pressure distribution along with the magnitude of the gripping force by tactile detection not only in the vertical direction but also in the horizontal direction has progressed. Therefore, the present applicant previously proposed a distributed pressure sensor formed by processing a semiconductor substrate as shown in FIGS. 4A to 4C.

FIG. 4A is a view of the sensor viewed from the back side of a silicon wafer which is a semiconductor substrate. In the case of this example, the sensor is 2 ×
The case where it is configured as an array of 2 is shown. Here, 30 is a distributed pressure sensor, and the distributed pressure sensor 30 is formed by cutting out from a silicon wafer, and the left half thereof is the detection unit 30.
A, the right half is the signal processing unit 30B. Thus, the deep groove portion 31 in the Y direction and the deep groove portion in the X direction are shown in the shaded portion of the back surface of the distributed pressure sensor 30 on the detection portion 30A side.
32 is drilled at the same depth with a dicer or the like, and further eight rectangular through holes 33 are formed by electric discharge machining or laser machining at the positions shown by intersecting lines along these deep groove portions 31 and 32. To do. Further, the portions shown by dots in FIG. 4A are the shallow groove portions 34, and after forming the deep groove portions 32 and 31 in the X and Y directions, the shallow groove portion 34 was used for the deep groove processing. A grindstone slightly thicker than the grinder of the dicer, and can be processed by scanning in the X and Y directions.

By performing such processing on the back surface side of the distributed pressure sensor 30 , it is possible to form a beam, which will be described later, having four protrusions 35 in the detection unit 30A.

FIG. 4B is a sectional view taken along the line PP of FIG. 4A,
As can be seen from FIG. 4B, the beam 40 in the X direction is formed by the deep groove portion 31, the shallow groove portion 34, and the protrusion portion 35 and is isolated by the rectangular through hole 33. FIG. 4C is a sectional view taken along the line Q-Q of FIG. 4A, showing the deep groove portion 3 in FIG. 4C.
2, the shallow groove portion 34, and the protrusion 35, the rectangular through hole 33
A beam 41 in the Y direction isolated by is formed.

FIG. 5 is a view of the distributed pressure sensor 30 viewed from the front surface side of the silicon wafer. In FIG. 5, the eight rectangular through holes 33 are used to form two X-direction beams 40 , 40 and two Y-direction beams 4.
It can be seen that 1 and 41 are formed. Then, a total of 16 strain gauges 42 are arranged on the beam 40 in the X direction and the beam 41 in the Y direction as shown in this figure.

Therefore, next, in the beam 40 in the X direction and the beam 41 in the Y direction configured as described above, the principle of detecting the load when a force is applied to the protrusion 35 will be described with reference to FIGS. 6 to 9. To do.

Now, as shown in FIG. 6, both ends are fixed by A and D,
To the protrusion 10 of the beam 11 having the protrusion 10 at its center,
If a vertical force F _V is applied, a strain having a distribution as shown in FIG. 7 is generated on the lower surface of the beam 11.

Further, as shown in FIG. 8, when a horizontal force F _H is applied to the same beam 11, a strain having a distribution as shown in FIG. 9 is generated on the lower surface of the beam 11. In addition, in FIGS. 7 and 9, the + symbol represents tensile strain, and the − symbol represents compressive strain.

Therefore, looking at the strains at points A to D in FIG. 6 with reference to FIGS. 7 and 9, large strains are generated at all points, and the vertical force is shown in FIG. Thus, at points A and D, -α [μstrain], and at points B and C, β
It becomes [μstrain]. That is, considering the symmetry of the beam, the strains at points A, D and B, C are equal.

Further, the strain generated when a horizontal force is applied becomes −γ [μstrain] at points B and D and δ [μstrain] at points A and C, as shown in FIG. The distortions at points A to D when a horizontal force is applied at the same time are as follows.

A point −α + δ B point β−γ C point β + δ D point −α−γ Therefore, the strain at each of A to D points forming the strain gauge is measured, and according to the following equations (1) and (2): If the calculation is performed, the vertical component force and the horizontal component force can be detected at the same time.

(Strain at point A-Strain at point B) + (Strain at point D-Strain at point C) = {(-α + δ)-(β-γ)} + {(-α-γ)-(β + δ)} = -2 (α +
β) (1) (distortion at point A-distortion at point B)-(distortion at point D-distortion at point C) = {(-α + δ)-(β-γ)}-{(-α-γ) − (Β + δ)} = 2 (γ +
δ) (2) That is, the component force in the vertical direction can be identified by the formula (1), and the component force in the horizontal direction can be identified by the formula (2).

The terms in these equations (strain at point A-strain at point B) can be detected by forming a half bridge between the strain gauge formed at point A and the strain gauge formed at point B,
One term (strain at point D-strain at point C) can be detected by forming a half bridge between the strain gauge formed at point D and the strain gauge formed at point C. That is, as shown in FIG. 10, the strain gauge 21 at the point A and the strain gauge 22 at the point B form the first half bridge,
Also, a strain gauge 23 at D point and a strain gauge 24 at C point
The second half bridge is formed by and the sum of the outputs from the respective half bridges is calculated by the summing amplifier 25 to obtain the vertical component force signal 26, and the difference between the outputs from the respective half bridges is obtained. When calculated by the differential amplifier 27, the horizontal component signal 28 is obtained.

Then, returning to FIG. 5 again, the half bridge shown in FIG. 10 is configured between the strain gauges 42 formed on the surface of the distributed pressure sensor 30 , and the signal processing circuit as shown in FIG. 10 is provided in the signal processing unit 30B. By arranging them, the force component in the vertical direction and the force component in the horizontal direction and in the X direction generated on the surface side of the distributed pressure sensor 30 are detected by the strain gauges 42 provided on the beam 40 in the X direction. be able to. Further, the strain gauge 42 group provided on the beam 41 in the Y direction allows the distributed pressure sensor 30.
It is possible to detect the component force in the vertical direction generated on the surface side of and the component force in the horizontal direction and in the Y direction.

In this example, since the beams 40 in the X direction and the beams 41 in the Y direction are arranged in a checkerboard pattern as shown in FIG. 5, the component force in the vertical direction is applied from the four beams and also in the X direction. The component force can be detected from the two beams in diagonal positions, and the component force in the Y direction can be detected from the two beams in different diagonal positions. The component force in the vertical direction of the force thus applied to the distributed pressure sensor 30 , the component force in the horizontal direction and the X direction, and the component force in the horizontal direction and the Y direction can be detected with high density distribution. .

[Problems to be Solved by the Invention]

By the way, in the case of the three-way component force detection type distributed pressure sensor of the above-mentioned form, there remains a problem to be solved that relatively large interference occurs between the respective sensor elements.

FIG. 11 shows a beam 40 in the X direction and a beam 41 in the Y direction (hereinafter referred to as the sensor element beam 50 ) that constitute the sensor element as shown in FIG. 5, and a support beam that supports the fixed end thereof. Part 60
It is a figure which shows the joining part with. As can be seen from FIG. 11, the width and thickness of the thin portion 61 corresponding to the deep groove portions 31 and 32 of the support beam portion 60 are the same as those of the thin portion 51 corresponding to the deep groove portions 31 and 32 of the sensor element beam 50. It is exactly the same, and it cannot be said that the bending and torsional rigidity as a supporting beam is sufficient.
If a load is applied to the protrusion 35 for this reason, the support beam
Relatively large bending and twisting are generated in 60 , and this influence also deforms other adjacent sensor element beams 50 to generate an interference output. Therefore, the above-described distributed pressure sensor has a problem that the load distribution applied to the sensor cannot be detected sufficiently accurately due to the interference between the sensor elements.

The object of the present invention is to pay attention to the above-mentioned problems, and in order to solve the problems, by providing the support beam portion with sufficient strength, the outputs from the respective sensor elements do not interfere with each other and the accurate load distribution is achieved. It is to provide a distributed pressure sensor capable of detecting

[Means for Solving the Problems]

In order to achieve such an object, the present invention provides a distributed pressure sensor with an X direction and a Y direction orthogonal to each other on a semiconductor substrate.
A plurality of pairs of rectangular through-holes are arranged in parallel in parallel with each other in the direction, and are alternately bored, and the sensor element beams in the X-direction and the Y-direction are formed between the pair of rectangular through-holes. A protrusion is provided at the center of each span of the sensor element beam on the surface, and thin portions are formed on both sides of the protrusion of the sensor element beam, and both ends of the thin portion are thicker than the thin portion, and , A plurality of strain gauges are arranged on the sensor element beam on the other surface of the semiconductor substrate so as to be supported by the central portion of the wide support beam portion, and the strain gauges are applied to the protrusions. A force component in the vertical direction on the semiconductor substrate and component forces in the X direction and the Y direction are made detectable, and a signal processing circuit for processing detection signals from a plurality of strain gauges is provided on the other side of the semiconductor substrate. And characterized by being formed in a part of.

[Action]

According to the present invention, the width and thickness of the support beam portion are made sufficiently larger than the beam portion of the sensor element beam excluding the protruding portion, so that the bending and torsional rigidity of the support beam portion can be made larger than that of the sensor element beam. Since it can be kept high and the bending and twisting of the support beam portion when a load is applied to the sensor element beam is suppressed, its influence is not transmitted to other sensor element beams through the support beam portion, and therefore the sensor It is possible to eliminate the interference related to the output between the elements.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail and specifically with reference to the drawings.

1A to 1C show an embodiment of the present invention. FIG. 1A is a view of the distributed pressure sensor 1 viewed from the back side of a silicon wafer which is a semiconductor substrate, and FIGS. 1B and 1C are 1A shows a cross section taken along the line PP and a cross section taken along the line QQ of FIG. 1A. In order to obtain such a distributed pressure sensor 1 , a silicon wafer cut out into a shape similar to that shown in FIG. 5 is prepared, and a signal having a strain gauge, an IC circuit, etc. is similarly formed on the surface thereof. A processing part is formed (not shown). Thus, a rectangular through hole 3 is formed from the back surface side of the silicon wafer 2 by leaving a portion corresponding to the sensor beam 5 including the strain gauge and a portion corresponding to the support beam portion 6 by a processing machine using electric discharge or laser. , As shown in FIG. 2A.

Next, as shown in FIG. 2B, deep grooves 8A are formed by electrical discharge machining or the like on both sides so that the protruding portion 7 is left at the center of the span of the sensor element beam 5, and the thin groove 8A of the sensor element beam 5 is formed by this deep groove 8A. To get Thereafter, the portions shown by dots in FIG. 1A are shallowly grooved by a processing machine such as a dicer, and the supporting beam portion 9 is formed by these shallow grooves 9A.

That is, in the distributed pressure sensor 1 of the present example, unlike the prior art, the deep groove machining by the dicer is not performed, and the deep groove 8A is formed only in the sensor element beam 5 by the electric discharge machining to form the thin wall portion 8. Therefore, the support beam portion 9 3 does not have a thin portion as shown in FIG. 3, and a sufficient thickness can be obtained as compared with the sensor element beam 5. Further, the support beam portion 9 has a sufficient width as compared with the sensor element beam 5, and thus has sufficient bending and torsional rigidity as compared with the sensor element beam 5. By comparing FIG. 3 with FIG. 11, it will be understood that the bending and torsional rigidity of the support beam portion 9 is enhanced by the present invention. Therefore, due to the high rigidity of the support beam portion 9, in the distributed pressure sensor 1 according to the present invention, the interference between the sensor elements can be made very small.

〔The invention's effect〕

As described above, according to the present invention, a distributed pressure sensor is alternately drilled by arranging a plurality of pairs of rectangular through holes in the X direction and the Y direction on a semiconductor substrate in parallel. In addition, the sensor element beams in the X direction and the Y direction are formed between the pair of rectangular through holes, and a protrusion is provided at the center of each span of the sensor element beams on one surface of the semiconductor substrate. Thin portions are formed on both sides of the protruding portion, and both ends of the thin portion are made thicker than the thin portion and are supported by the central portion of the wide support beam portion. A plurality of strain gauges are arranged on the sensor element beam on the other surface, and a component force of a force applied to the protrusion by the plurality of strain gauges in a direction perpendicular to the semiconductor substrate, the X direction and the Y direction. Component force is no to allow detection of, was made by forming a signal processing circuit for processing the detection signals from the plurality of strain gauges to a portion of the other surface of the semiconductor substrate. Therefore, the rigidity of the support beam portion can be increased,
It has become possible to suppress interference between the sensor elements and accurately detect the force distribution from the sensor elements arranged in high density.

[Brief description of drawings]

FIG. 1A is a plan view showing an example of the configuration of the semiconductor substrate of the distributed pressure sensor of the present invention when viewed from the back side, FIG. 1B is a sectional view taken along the line PP of FIG. 1A, and FIG. 1C is FIG. 1A. FIG. 2A is a sectional view taken along the line Q-Q in the figure, FIG. 2A is a diagram showing a through hole processing state of the distributed pressure sensor shown in FIG. 1A, and FIG. 2B is a state in which a thinner portion is formed from the state of FIG. 2A. Fig. 3 is a perspective view showing the relative relationship between the sensor element beam and the support beam portion according to the present invention, and Fig. 4A is a plan view showing an example of the configuration of the distributed pressure sensor when viewed from the back side. 4B is a sectional view taken along the line PP of FIG. 4A, FIG. 4C is a sectional view taken along the line QQ of FIG. 4A, and FIG. 5 is a layout view of the strain gauge in the distributed pressure sensor shown in FIG. 4A. 6 to 9 are views for explaining the principle of detecting the three-component force by the distributed pressure sensor shown in FIGS. 4A to 4C, and FIG. 10 is the distributed pressure sensor shown in FIGS. 4A to 4C. Fig. 11 is a configuration diagram of a signal processing circuit that processes a signal from a strain gauge in Fig. 11, and Fig. 11 is a perspective view showing a relative relationship between a sensor element beam and a support beam portion in the distributed pressure sensor shown in Figs. 4A to 4C. is there. 1 , 30 …… Distributed pressure sensor, 3,33 …… Rectangular through hole, 5 …… Sensor element beam, 7 …… Projection part, 8 …… Thin wall part, 8 A ・ ・ ・ Deep groove, 9 …… Support beam part, 9A: shallow groove, 30A: detection part, 30B: signal processing part, 42: strain gauge.

Claims (1)

[Claims] 1. A plurality of pairs of rectangular through holes arranged in parallel in the X direction and the Y direction perpendicular to each other on a semiconductor substrate are alternately arranged in parallel, and the pair of rectangular through holes are formed between the pair of rectangular through holes. A sensor element beam in the X direction and the Y direction is formed, a protrusion is provided at the center of each span of the sensor element beam on one surface of the semiconductor substrate, and thin portions are formed on both sides of the protrusion of the sensor element beam. And both ends of the thin portion are supported by the central portion of the support beam portion having a thickness larger than that of the thin portion and wider than the thin portion. A plurality of strain gauges are arranged on the sensor element beam, and a component force of a force applied to the protrusion by the plurality of strain gauges in the vertical direction with respect to the semiconductor substrate, in the X direction and the Y direction. No such force detectable, distributed pressure sensation sensor characterized by being formed in a part of the other surface of the semiconductor substrate a signal processing circuit for processing the detection signals from the plurality of strain gauges.