JPH0663887B2 - Distributed pressure sensor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a distributed pressure sensor, and more particularly, to a distributed pressure sensor that can be attached to the surface of a robot hand or the like to detect the distribution of force applied to the hand. Regarding sensors.

[Prior Art] A distributed pressure sensor has been developed mainly for the purpose of obtaining information on the magnitude of gripping force, surface pressure distribution, etc. by detecting the pressure sense mainly in a robot hand or the like. As a distributed pressure sensor that can detect not only the vertical force on the sensor surface but also the horizontal force distribution,
The one shown in the figure has been proposed. In this example, the silicon wafer on which the sensor is formed is viewed from the back side,
The distributed pressure sensor 30 is formed by cutting out from a silicon wafer. The left half of the distributed pressure sensor 30 is a detection unit 30A and the right half is a signal processing unit 30B.
Is. In this manner, the deep groove portion 31 in the Y direction and the deep groove portion 32 in the X direction are drilled at the same depth on the back surface of the distributed pressure sensor 30 shown by hatching on the side of the detection portion 30A at the same depth. Furthermore, eight rectangular through holes 33 are provided at the positions shown by crossing along these deep groove portions 31 and 32.
Are formed by electric discharge machining or laser machining. Further, the portions indicated by dots in FIG. 1 are shallow groove portions 34, and after forming the deep groove portions 32 and 31 in the X and Y directions, the portion shown in the drawing was used for 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 , a beam having four protrusions 35 can be formed in the detection unit 30A.

FIG. 2 is a sectional view taken along the line PP of FIG.
As can be seen from the drawing, 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, which is separated by the rectangular through hole 33. Further, FIG. 3 shows a Q-Q cross section of FIG. 1, and in FIG. 3, a beam in the Y direction separated by the rectangular through hole 33 by the deep groove portion 31, the shallow groove portion 34, and the projection portion 35. 41 is formed.

FIG. 4 is a view of the distributed pressure sensor 30 as seen from the surface of the silicon wafer. In FIG. 4, eight rectangular through holes
By 33, two beams 40 in the X direction 40 , 40 and two beams in the Y direction 41 ,
It turns out that 41 is formed.

Thus, the X direction beam 40 and the Y direction beam 41 are each formed with four semiconductor strain gauges 42, four in total, and the right half surface of the distributed pressure sensor 30 has a signal processing unit. Is a signal processing unit 30B in which an electronic circuit for is formed.

Next, how the load is detected by the beam 40 in the X direction and the beam 41 in the Y direction will be described below.

5 to 8 explain the principle of the detection.

Now, as shown in FIG. 5, when a vertical force F _V is applied to the projecting portion 10 of the beam 11 having both ends fixed and the projecting portion 10 at the center portion thereof, As shown in the figure,
Distortion of distribution occurs.

Further, as shown in FIG. 7, when a horizontal force F _H is applied to the protrusion 10 of the same beam 11, a strain having a distribution as shown in FIG. 8 is generated on the lower surface of the beam 11. Incidentally, these FIG. 6 and FIG.
In the figure, the + symbol represents tensile strain, and the-symbol represents compressive strain.

Then, looking at the strains at points A to D in FIG. 5 with reference to FIGS. 6 and 8, large strains occur at any points, and the vertical force is shown in FIG. Thus, at points A and D, α [μstrain], and at points B and C β [μstrain]
strain]. That is, considering the symmetry of the beam, A,
The distortions at point D and points B and 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, a strain gauge is formed at points A to D, and the strain at each point is measured, and the following equations (1) and (2 ), The vertical 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 force in the vertical direction can be identified by the equation (1), and the force in the horizontal direction can be identified by the equation (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. 9, the strain gauge 21 at the point A and the strain gauge 22 at the point B form the first half bridge,
A strain gauge 24 at C point and a strain gauge 23 at D point
By forming a second half bridge by and the sum of the outputs from each half bridge is calculated by the summing amplifier 25, a vertical component signal 26 is obtained, while the difference between the outputs from each half bridge is calculated. When calculated by the differential amplifier 27, the horizontal component signal 28 is obtained.

Therefore, in the beam 40 in the X direction as shown in FIG. 4, the semiconductor strain gauges 42A, 42B, 42C and 42D are formed in the longitudinal direction on the center line of the beam 40 in the X direction as shown in FIG. By incorporating these semiconductor strain gauges into the half bridge of the form shown in FIG. 9 and performing signal processing in the signal processing unit 30B, the vertical component force F _z and the horizontal component force F _x applied to the protrusion 35 are generated. Can be detected.
Further, also in the beam 41 in the Y direction, the vertical component force F _z ,
The horizontal component force F _y can be detected. Therefore, each sensor element can detect the component forces F _z and F _x , or the component forces F _z and F _y, and the distributed pressure sensor 30 as a whole can calculate the distribution of the load applied to the surface as x, y, z direction component force, F _x , F _y ,
It can be detected by being decomposed into F _z .

[Problems to be Solved by the Invention] However, when actually using the distributed pressure sensor 30 as described above, for example, as shown in FIG. 11, the outer circumference of the silicon wafer on which the sensor is formed is shaded on the surface side. Department
When 45 is fixedly held on the lower substrate 46 by an adhesive layer 47 or soldering as shown in FIG. 12, FIG. 12 shows a beam in the X direction corresponding to the PP cross section shown in FIG. Of both ends of 40 , one end is fixed and supported directly on the outer peripheral portion 45, while the other end is fixed and supported on the central portion of the fixed support beam 48 formed by the shallow groove 34.

That is, as shown in FIG. 13, the supporting condition of the beam 40 in the X direction is such that one end portion is purely fixedly supported, and the other end portion is fixedly supported at the central portion of the both ends fixed support beam 48 . By the way, as described above, the principle of load detection of the distributed pressure sensor 30 is that the both ends of the left and right symmetrical fixed beams centering on the protrusion 35 are used as the base, and the direction of the X direction as shown in FIG. from the beam 40 in the beam of the asymmetry of the interference due to the horizontal component force F _x in the case of identifying the vertical component force F _z, by the vertical component force F _z in the case of identifying a similarly horizontal component force F _x There is a lot of interference. The same applies to the beam 41 in the Y direction. That is, in the distributed pressure sensor 30 described above, there is still a problem in that the distributed load applied to the sensor surface is decomposed into three-direction component forces and accurately detected.

The present invention, in order to solve the problems described above,
In each sensor element, the load applied to the protrusion can be accurately decomposed into three component forces in the vertical and horizontal directions and can be detected, and as a whole, can be accurately decomposed into three component forces and detected. It is intended to provide a tactile sensor.

[Means for Solving the Problem] In order to achieve such an object, the present invention provides a plurality of pairs of rectangular through holes arranged in parallel in the X direction and the Y direction orthogonal to each other on a semiconductor substrate. Along with
Beam portions in the X and Y directions are formed between a pair of rectangular through holes, a protrusion is provided at the center of the span of each beam on one surface of the semiconductor substrate, and thin portions are provided on both sides of the protrusion. The beam support portions are formed on both sides of the thin-walled portion, and a plurality of strain gauges are formed on the beam portion on the other surface of the semiconductor substrate, and the semiconductor of the force applied to the protrusion by the plurality of strain gauges is formed. A distributed pressure sensor capable of detecting a component force in a vertical direction with respect to a substrate and a component force in an X direction and a Y direction, wherein a central portion of a support beam orthogonal to a beam portion outside a thin portion in the beam portion in the X direction and the Y direction. It is characterized in that they are each fixed and supported.

[Operation] According to the present invention, a beam having a protrusion in the center of the span and thin portions symmetrically formed on both sides of the protrusion has both ends at the center of the fixed beam formed by the thick portion. Since it is fixedly supported, the beam support conditions are the same on both sides of the protrusion, and there is no mutual interference between the component forces of the load applied to the protrusion in the three directions. It is possible to accurately decompose and detect the two-component force in the directions orthogonal to each other.

Embodiments Embodiments of the present invention will be described in detail and specifically below with reference to the drawings.

14A to 14C show an example of the distributed pressure sensor 300 of the present invention, and FIG. 14A shows the silicon wafer viewed from the back side. Also in this example, the deep groove portion 31 is formed in the vertical direction.
And the shallow groove portion 34, and the deep groove portion 32 and the shallow groove portion 34 in the lateral direction are formed in the same manner as in FIG. 1, but in the case of this example, the deep groove portion 31A is formed in the vertical direction as compared with FIG. Are formed on both sides in large numbers, and in the same manner in the lateral direction, one deep groove portion 32A is formed on each of the upper and lower sides.

Furthermore, the difference from FIG. 1 is that these new deep groove portions 31A are provided.
And 32A are newly provided with four rectangular through holes 33A. The distributed pressure sensor 30 configured in this way
The PP cross section and the QQ cross section of 0 are shown in FIG. 15 and FIG. As can be seen by comparing these figures with FIGS. 2 and 3, both ends of the beam 140 in the X direction and the beam 141 in the Y direction are supported by fixed support beams 48 separated by rectangular through holes 33 and 33A. Has been done.

Therefore, when such a distributed pressure sensor 300 is fixed to the lower substrate 46 as shown in FIGS. 17 and 18,
The beam 140 in the X direction and the beam 141 in the Y direction are both fixedly supported at the central portion of the fixed support beam 48 in the form shown in FIG. It is kept symmetrical. Therefore, it is possible to eliminate the mutual interference between the component forces generated due to the asymmetric support condition of the beam, and the load applied to the protrusion 35 is converted into the component forces in the three directions of X, Y and Z by the semiconductor strain gauge 42. It can be accurately decomposed and detected.

20 and 21 show another embodiment of the present invention. In this example, in addition to the first embodiment shown in FIGS. 14A to 14C, four rectangular through holes 33B and four square through holes 33C are drilled along the surrounding deep groove portions 31A and 32A. By arranging these through holes symmetrically with respect to the X direction and the Y direction, the supporting conditions at both ends of the fixed support beam 48 are made uniform, whereby the beam 140 in the X direction and the beam 141 in the Y direction are provided. It is possible to make the supporting condition of 1 more completely uniform.

[Effects of the Invention] As described above, according to the present invention, a plurality of pairs of rectangular through holes are formed in parallel on the semiconductor substrate in the X direction and the Y direction orthogonal to each other, and Beam portions in the X direction and the Y direction are formed between the pair of rectangular through holes, and a projection portion is provided at a span center portion of each of the beam portions on one surface of the semiconductor substrate. Forming thin-walled portions on both sides and beam-supporting portions on both sides of the thin-walled portion, and forming a plurality of strain gauges on the beam portion on the other surface of the semiconductor substrate by the plurality of strain-gauges. In a distributed pressure sensor capable of detecting a component force of a force applied to the protrusion in a direction perpendicular to the semiconductor substrate and a component force in the X direction and the Y direction, beams at both ends of a beam portion in the X direction and the Y direction. Support section Since it was fixed to the central part of the support beam orthogonal to the beam part, the supporting condition of the beam centering on the protrusion is kept symmetrical, and the loads applied to the protrusion do not interfere with each other, It is now possible to accurately decompose and detect the three-component force in the direction perpendicular to the beam and in the horizontal direction orthogonal to each other, and it is possible to provide a distributed pressure sensor with high detection accuracy.

[Brief description of drawings]

FIG. 1 is a plan view showing an example of the configuration of a semiconductor substrate in a conventional distributed pressure sensor as viewed from the pressurizing side, FIG. 2 is a sectional view taken along the line PP of FIG. 1, and FIG. A Q-Q line sectional view, FIG. 4 is a layout view of a strain gauge in the distributed pressure sensor shown in FIG. 1, and FIGS. 5 to 8 are explanations of the detection principle by the sensors shown in FIGS. 1 and 4. FIG. 5 is a diagram showing a state in which a vertical force is applied to the fixed-end beam structure, FIG. 6 is a distribution diagram of stress generated in the lower part of the beam in the case of FIG. 5, and FIG. Is a diagram showing a state in which a horizontal force is applied to the beam structure shown in FIG. 5, FIG. 8 is a distribution diagram of stress generated in the lower part of the beam in the case of FIG. 7, and FIG. 9 is shown in FIG. Fig. 10 is a configuration diagram of a signal processing circuit from the strain gauge shown in Fig. 10, and Fig. 10 is a plan view schematically showing an arrangement on the beam of the strain gauge shown in Fig. 9. 11 and 12 are bottom views showing the state in which the conventional distributed pressure sensor shown in FIGS. 1 to 4 is fixed on the lower substrate as seen from the back side, and FIG. 13 is the distributed pressure sensor. FIG. 14A is a perspective view schematically showing the support structure of the beam portion of FIG. 14, FIG. 14A is a plan view showing the configuration of the semiconductor substrate of the distributed pressure sensor of the present invention viewed from the pressurizing side, FIGS. 14B and 14C are FIG. 14A. FIG. 15 is a side view showing the same as seen from the A direction and the B direction, and FIGS. 15 and 16 show the PP line and QQ of FIG.
FIG. 17 is a sectional view taken along the line of FIG. 17 and FIG. 18, showing a bottom view and a sectional view of the distributed pressure sensor of the present invention fixed on the lower substrate as viewed from the back side. FIG. 20 is a perspective view schematically showing the support structure of the constituted beam portion, and FIGS. 20 and 21 are a plan view and a bottom view, respectively, of the semiconductor substrate according to another embodiment of the present invention viewed from the pressure side and the opposite side thereof, respectively. Is. 21 to 24 …… Strain gauge, 25 …… Adding amplifier, 27 …… Differential amplifier, 30 , 300 …… Distributed pressure sensor, 30A …… Detector, 30B …… Signal processor, 31,32,31A, 32A ... deep groove, 33,33A, 33B, 33C ... rectangular through hole, 34 ... shallow groove, 35 ... protrusion, 40 , 41 , 140 , 141 ...... X direction beam, Y direction beam, 42 …… Semiconductor strain gauge, 48 …… Solid support beam.

Claims (1)

[Claims] 1. A plurality of pairs of rectangular through holes are formed in parallel on the semiconductor substrate in the X direction and the Y direction orthogonal to each other, and the X direction is provided between the pair of rectangular through holes. And a beam portion in the Y direction, a protrusion is provided at the center of each span of the beam on one surface of the semiconductor substrate, thin portions are formed on both sides of the protrusion, and a thin portion is further formed. Beam support portions are formed on both sides, a plurality of strain gauges are formed on the beam portion on the other surface of the semiconductor substrate, and the force applied to the protrusions by the plurality of strain gauges is applied to the semiconductor substrate. In a distributed pressure sensor capable of detecting a component force in a vertical direction and a component force in the X direction and the Y direction, an outer side of the thin portion of the beam portion in the X direction and the Y direction of a support beam orthogonal to the beam portion. Center A distributed pressure sensor characterized by being fixed to and supported by the respective parts.