JP2005351653A - Pressure sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately detect pressure distribution in a cylinder axis direction on a cylindrical surface even in cases where pressure sensors are disposed thereon each in a bent or curved shape by devising a bonded structure of conductive pressure-sensitive rubbers to an electrode substrate and a bonded structure of the pressure-sensitive rubbers to a protective film disposed thereon. <P>SOLUTION: The plurality of conductive pressure-sensitive rubbers 12 are disposed on the flexible electrode substrate 11 and the flexible protective film 13 is disposed on the pressure-sensitive rubbers 12 with some looseness. Each of the rubbers 12 is formed into a strip shape and disposed so that its length 12a agrees with a direction (Y-direction) in which the electrode substrate 11 has a smaller curvature when disposed on a cylindrical base material, and the rubbers 12 are disposed so that they are fixedly spaced along a direction (X-direction) in which the electrode substrate 11 has a larger curvature. Widthwise both end parts 12b and 12b are bonded/fixed to the electrode substrate 11 while both end parts 13a and 13a in the X direction of the protective film 13 are bonded/fixed to the electrode substrate 11. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pressure-sensitive sensor in which conductive pressure-sensitive rubber is disposed on a flexible electrode substrate, and more particularly to a distributed pressure-sensitive sensor disposed on a substrate having a cylindrical surface.

  Conventionally, a pressure-sensitive sensor in which a conductive pressure-sensitive rubber is disposed on a flexible electrode substrate has been provided (see, for example, Patent Document 1).

In this pressure-sensitive sensor, strip-shaped conductive pressure-sensitive rubbers are arranged on a flexible substrate at regular intervals, and these are fixed by sandwiching them from above and below with polyethylene adhesive tape (hereinafter simply referred to as “film”). Yes. The purpose of this pressure-sensitive sensor is to make it possible to attach the pressure-sensitive sensor to a curved flexible body by preventing changes in conductivity due to bending of the pressure-sensitive conductive rubber. That is, the conventional pressure sensitive sensor cannot detect the pressure distribution, but its accuracy is not taken into consideration.
JP-A-4-38432

  Therefore, when the pressure sensor having the above structure is used as a distributed pressure sensor, the following problems occur. Here, the distributed pressure sensor refers to a pressure sensor having a structure in which parallel electrodes for detection are arranged in an array on a flexible electrode substrate and conductive pressure sensitive rubber is arranged thereon.

That is, since the conductive pressure-sensitive rubber is bonded only to the film on the upper surface and the electrode substrate is bonded only to the film on the lower surface, the positional relationship between the conductive pressure-sensitive rubber and the electrode on the electrode substrate is easily shifted, and the pressure distribution Accuracy and reproducibility are reduced in detection.
When the conductive pressure-sensitive rubber is bonded with the electrode substrate from above and below with a film, the rigidity in the direction perpendicular to the bending direction of the top film (hereinafter referred to as “bending axis direction”) increases when the pressure sensor is bent, and the bending axis The pressure distribution in the direction cannot be detected.
Even if the conductive pressure-sensitive rubber is made into a strip shape, the conductive pressure-sensitive rubber is fixed with a film so as to be sandwiched from above and below, so the film may be pressed when the sensor is bent, and the resistance value of the conductive pressure-sensitive rubber may decrease. .

  When the film is adhered to the surface of the conductive pressure-sensitive rubber, the conductive pressure-sensitive rubber is pulled by the film when the electrode substrate is placed, for example, bent or curved on a cylindrical surface (that is, the peripheral side surface of the cylindrical body). Since it is already distorted in the form of no contact, the dynamic range is reduced.

  The present invention has been devised to solve such problems, and the object thereof is an adhesive structure between the conductive pressure-sensitive rubber and the electrode substrate, and an adhesive structure between the conductive pressure-sensitive rubber and the protective film disposed thereon. By devising the above, it is an object of the present invention to provide a pressure-sensitive sensor that can accurately detect the pressure distribution in the cylindrical axis direction even when the pressure-sensitive sensor is bent or curved on a cylindrical surface, for example.

  In order to solve the above problems, the pressure-sensitive sensor of the present invention is a pressure-sensitive sensor in which a conductive pressure-sensitive rubber is disposed on a flexible electrode substrate, and the conductive pressure-sensitive rubber is formed in a strip shape, A plurality of the conductive pressure-sensitive rubbers are arranged so that the long side thereof coincides with the direction in which the curvature of the electrode substrate is small, and at regular intervals along the direction in which the curvature of the electrode substrate is large, Only the short side of the conductive pressure-sensitive rubber arranged in this manner is bonded and fixed to the electrode substrate.

  According to the present invention having such a feature, the relative position between the conductive pressure-sensitive rubber and the electrode on the electrode substrate is less likely to be shifted by bonding only the short side of the conductive pressure-sensitive rubber to the electrode substrate (FPC). In addition, accuracy and reproducibility can be maintained in pressure distribution detection. In addition, in a pressure-sensitive sensor of a type in which an electrode substrate is wound around a circumferential curved surface of a cylindrical body, it is possible to accurately detect a pressure distribution even in the axial direction of the cylindrical body.

Further, according to the pressure-sensitive sensor of the present invention, the flexible protective film is disposed on the conductive pressure-sensitive rubber so as to have a slack, and only the end portion of the protective film is bonded and fixed to the electrode substrate. It is a feature.
As described above, the protective film is disposed only on the upper surface of the electrode substrate (that is, the upper surface of the conductive pressure-sensitive rubber), and the protective film and the conductive pressure-sensitive rubber have a non-adhesive structure. Compared to the conventional structure in which the pressure sensitive rubber is sandwiched between the upper and lower sides of the film, the sensitivity and dynamic range of the sensor can be easily maintained, and the bendable angle can be expanded as compared with the conventional structure. Furthermore, since the protective film is not directly bonded to the conductive pressure-sensitive rubber, distortion during pressurization is not hindered by the adhesive, and detection sensitivity can be maintained. In this case, the protective film on the upper surface is loosened, so even when the pressure-sensitive sensor is bent or curved, the protective film on the upper surface does not press the conductive pressure-sensitive rubber. The dynamic range can be maintained.

  According to the pressure-sensitive sensor of the present invention, by adhering only the short side of the conductive pressure-sensitive rubber to the electrode substrate, the relative position between the conductive pressure-sensitive rubber and the electrode on the electrode substrate becomes difficult to shift, and in pressure distribution detection Accuracy and reproducibility can be maintained. In addition, when the electrode substrate is wound around the circumferential surface of the cylindrical body, the pressure distribution can be accurately detected also in the axial direction of the cylindrical body. In addition, the non-adhesive structure of the protective film and the conductive pressure-sensitive rubber makes it easier to maintain the sensitivity and dynamic range of the sensor compared to the conventional structure in which the electrode substrate and the conductive pressure-sensitive rubber are sandwiched between the upper and lower sides of the film. In addition, the bendable angle can be expanded more than the conventional one. Furthermore, since the protective film is not directly bonded to the conductive pressure-sensitive rubber, distortion during pressurization is not hindered by the adhesive, and detection sensitivity can be maintained. By mounting this sensor on the fingertip of the robot hand, the contact position can be detected with an accuracy within ± 0.7 mm.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1A is a plan view of the flexible pressure-sensitive sensor 1 according to the present embodiment viewed from above in a flat state, and FIG. 1B is a side view thereof. 2A is a perspective view showing a state in which the pressure-sensitive sensor 1 shown in FIG. 1 is arranged on the cylindrical base material 51, and FIG. 2B is a cross section taken along the line AA in FIG. FIG.

  As shown in FIG. 1, the pressure-sensitive sensor 1 according to the present embodiment includes a plurality of (four in the present embodiment) conductive pressure-sensitive rubbers 12 arranged on a flexible electrode substrate (Flexible Printed Circuit: FPC) 11. The conductive pressure-sensitive rubber 12 is formed in a strip shape.

  Further, on the electrode substrate 11, three spiral parallel electrodes 11a, 11a,... Are arranged at regular intervals in the vertical direction (Y direction in FIG. 1A) and in the horizontal direction (FIG. 1A). A total of 12 pieces are arranged and printed in the (X direction). That is, the parallel electrodes 11a, 11a,... Have 12 elements, and the resistance value between the parallel electrodes is detected by an external circuit (not shown).

The conductive pressure-sensitive rubber 12 has a long side 12a that coincides with a direction in which the curvature of the electrode substrate 11 is small (Y direction in FIG. 1A) when placed on a cylindrical base 51 described later. And four pieces are arrange | positioned so that it may become a fixed space | interval along the direction (X direction in FIG.1 (a)) with a large curvature of the electrode substrate 11. FIG. That is, four conductive electrodes 12 are arranged so as to cover the three parallel electrodes 11a, 11a, 11a arranged in a vertical row. And only the both ends 12b and 12b of the short side of each conductive pressure-sensitive rubber 12 arranged in this way are bonded and fixed to the electrode substrate 11. That is, the adhesion location is a location away from the parallel electrodes 11a, 11a, and 11a, and the conductive pressure-sensitive rubber 12 and the three parallel electrodes 11a, 11a, and 11a disposed below are bonded and fixed. There is no state.
By arranging in this way, the resistance value of the conductive pressure-sensitive rubber 12 can be detected by the 12 parallel electrodes 11a, 11a. That is, the pressure distribution can be detected. In this case, by bonding the conductive pressure sensitive rubber 12 and the electrode substrate 11, there is no relative displacement between the conductive pressure sensitive rubber 12 and the parallel electrode 11a, and accuracy and reproducibility can be maintained in pressure distribution detection. . In addition, compared with the conventional structure in which the electrode substrate and the conductive pressure-sensitive rubber are sandwiched between the upper and lower sides of the film, the sensitivity and dynamic range of the sensor can be easily maintained, and the bendable angle can be increased as compared with the conventional structure.

However, the bonding position is not limited to the end portion 12b on the short side of the conductive pressure-sensitive rubber 12, but as shown in FIG. 2, a portion 12c (in FIG. 5, each parallel electrode) other than the electrode portion (parallel electrode 11a). It may be bonded to both ends of the long side 12a via 11a. In the case of FIG. 5, although depending on the thickness of the adhesive, the size of the conductive pressure-sensitive rubber 12 and the parallel electrode 11a, and the sensitivity of the conductive pressure-sensitive rubber 12, the sensitivity of contact detection is compared to the adhesion of only the short side, It may be reduced to two-thirds. However, bonding a part of the long side 12a has a relatively small influence on the sensitivity, and the bonding location and area may be determined based on the sensitivity distribution of the sensor.
The flexible protective film 13 is arranged with a slight slack so as to cover the whole of the four conductive pressure-sensitive rubbers 12 arranged in four rows. This protective film 13 is provided only at both end portions 13a and 13a in the direction in which the curvature of the electrode substrate 11 is large (the X direction in FIG. 1A) when the pressure-sensitive sensor 1 is disposed on a cylindrical base 51 described later. Is bonded and fixed to the electrode substrate 11. That is, the protective film 13 and each conductive pressure-sensitive rubber 12 disposed thereunder are not bonded and fixed.

  In the above configuration, one conductive pressure-sensitive rubber 12 is arranged per one vertical row of the parallel electrodes 11a, but a plurality of rows such as two rows and three rows are covered with one strip-like conductive pressure-sensitive rubber 12. May be. The number of rows covered with one conductive pressure-sensitive rubber depends on the sensitivity of the conductive pressure-sensitive rubber 12, the magnitude of curvature when the pressure-sensitive sensor 1 is disposed on a cylindrical base 51 described later, and the like. It may be determined by.

  FIG. 3 shows a state in which the pressure-sensitive sensor 1 having the above configuration is arranged on the cylindrical base material 51.

  As shown in FIG. 3B, even when the pressure-sensitive sensor 1 of the present embodiment is arranged bent (curved) along the peripheral side surface of the cylindrical base material 51, the protective film 13 has a slack and has an electrode. Since it is adhesively fixed to the substrate 11, the protective film 13 is not in a state of pressing each conductive pressure-sensitive rubber 12.

  FIG. 4 shows a state in which the pressure-sensitive sensor 1 of the present embodiment arranged on the peripheral side surface of the cylindrical base material 51 as shown in FIG. 3 is cut in the cylindrical axis direction along the line BB in the drawing. It is sectional drawing, the figure (a) shows the state which has not pressurized, and the figure (b) has shown the state pressurized at one point on the parallel electrode 11a2 located in a center part. FIG. 5 is a sectional view in the axial direction of the cylinder in a state in which a pressure-sensitive sensor having a conventional structure in which the conductive pressure-sensitive rubber 12 and the protective film 13 are bonded with an adhesive 14 is disposed on the peripheral side surface of the cylindrical substrate. 4A shows a state where no pressure is applied, and FIG. 4B shows a state where pressure is applied at one point on the parallel electrode 11a2 located in the central portion. That is, FIG. 4B and FIG. 5B show a state in which one point on the parallel electrode 11a2 located at the center is pressurized with the same pressure.

  In the conventional pressure-sensitive sensor in which the conductive pressure-sensitive rubber 12 and the protective film 13 are bonded and fixed, if the cylinder is bent (curved), the rigidity of the protective film 13 at the bent portion (curved portion) increases. Therefore, as shown in FIG. 5B, even if pressure is applied at one point, the area where the protective film 13 presses the conductive pressure-sensitive rubber 12 increases, and it is located not only on the central parallel electrode 11a2 but also on both sides thereof. The conductive pressure-sensitive rubber 12 on the parallel electrodes 11a1 and 11a3 is also distorted. For this reason, all three parallel electrodes 11a1, 11a2, and 11a3 output, and an accurate pressure distribution cannot be detected.

  On the other hand, when the protective film 13 is not bonded to the conductive pressure-sensitive rubber 12 but is loosened and bonded to the electrode substrate 11, the conductive film 13 on the parallel electrode 11a2 in the central portion is bonded as shown in FIG. Since only the pressure sensitive rubber 12 is distorted and does not affect the parallel electrodes 11a1 and 11a3 on both sides thereof, only the central parallel electrode 11a2 outputs. Thereby, an accurate pressure distribution can be detected.

  From the results shown in FIGS. 4 and 5, the following can be said.

  That is, in the pressure sensitive sensor 1 of the type in which the electrode substrate 11 is wound around the circumferential side surface of the cylindrical base material, the pressure distribution can be detected also in the cylindrical axis direction. Further, since the protective film 13 on the upper surface is not directly bonded to the conductive pressure-sensitive rubber 12, distortion during pressurization is not hindered by the adhesive, and sensitivity is maintained. Further, by loosening the protective film 13, the protective film 13 can be prevented from pressing the conductive pressure-sensitive rubber 12 when the sensor is bent, and the dynamic range can be maintained even in the bent state.

  Next, the sensitivity of the pressure-sensitive sensor 1 when the surface of the protective film 23 is covered with a flexible silicone resin will be examined.

  That is, the pressure-sensitive sensor 1 of the present invention is disposed on the cylindrical base material 51, a flexible layer (silicone) having a uniform thickness is disposed on the surface of the protective film 13, and the silicone and the electrode substrate (FPC) 11 It is also possible to detect the pressure distribution applied to the silicone surface by adhering. With such a structure, the conductive pressure-sensitive rubber 12 and the electrode substrate (FPC) 11 can be protected. Hereinafter, the pressure sensor having such a configuration is referred to as a pressure sensor 2.

  Below, the contact position detection performance of this pressure sensor 2 is verified by experiment.

<Experimental example>
In this experiment, the interval between the parallel electrodes is set to a pitch of 2 mm in both the X direction and the Y direction in FIG. Silicone thickness is about several millimeters. The resistance value measured by each element (parallel electrode 11a) is binarized with an appropriate threshold value, and the presence / absence of contact is determined. Hereinafter, an element (parallel electrode) determined to be a contact is defined as an output element. The center-of-gravity positions of all output elements are calculated and detected as contact positions.

  This pressure sensor 2 is fixed, and a normal force 50 gf is applied to each element on a 2 mm square plane, and the contact position at that time is detected. The measurement was repeated 10 times for each of three points on the same pressure-sensitive rubber, and the reproducibility was evaluated. Regarding the contact position detection variation (3σ, 3 times the standard deviation) for each element, the first point is 0.3 mm in the circumferential direction (X direction in FIG. 1A), and the axial direction (in FIG. 1A). (Y direction) 0.7 mm, the second point was 0.0 mm in the circumferential direction, 0.0 mm in the axial direction, and the third point was 0.5 mm in the circumferential direction and 0.0 mm in the axial direction. Thus, when the contact plane was a 2 mm square plane, it was confirmed that the variation was within ± 0.7 mm in the axial direction.

<Comparative example>
When the conductive pressure-sensitive rubber is bonded and fixed as shown in FIG. 6 with the same sensor shape as the above-described experimental example (the entire circumference is bonded and fixed), the pressure-sensitive sensitivity is reduced by about 1/2 to 1/5. Also, in the contact position detection, the reproducibility is reduced by about a half.

  Specifically, the pressure-sensitive sensor 1 of the present invention can be used in a finger mechanism unit of a robot hand that holds an object with a plurality of finger mechanism units. The pressure sensor 2 can also be used for the fingertip portion of a similar robot hand. In this case, the contact area between the grasped object and the fingertip portion is increased by the flexible layer, and a more stable operation such as grasping can be performed.

  A robot hand having a structure similar to that of a human hand has a plurality of finger mechanism portions mounted on a base corresponding to the palm, and each finger mechanism portion is provided with a plurality of frame portions (a cylinder having the above-described configuration) via a plurality of joint portions. In the shape of the base material 51). And the actuator which operates each joint part is provided in the appropriate location. This robot hand can not only hold an object with a plurality of finger mechanisms, but also can hold various objects with different hardness, material, shape, etc. by mounting the pressure sensor of the present invention.

  7 to 10 show an example of the configuration of such a robot hand. FIG. 7 is a plan view (top view) of the robot hand viewed from the back side of the hand, and FIG. 8 is a side view of the robot hand viewed from the thumb side. FIG. 9 is a side view seen from the little finger side, and FIG. 10 is a plan view (bottom view) seen from the palm side.

The robot hand includes a base 61 corresponding to the palm, a plurality of finger mechanisms 62, 63, 64, 65, 66 (same as human fingers in this example) attached to the base 61, and each finger. And a drive unit that drives the mechanism units 62, 63, 64, 65, and 66. The drive unit includes a plurality of motors as actuators and wires (not shown) as power transmission units that transmit the driving force of each motor to the finger mechanism units 62, 63, 64, 65, and 66.
The motor which is a drive part is stored in 3 planes in the base 61 part. Thumb motors 72 to 74 for driving the thumb finger mechanism 62 on the first plane are arranged, and index finger motors 76 to 78 for driving the index finger mechanism 63 on the second plane; A ring finger / little finger motor 81 that drives the ring finger mechanism 64 and the little finger mechanism 65 is disposed. A motor 71 for driving the thumb finger mechanism 62 in parallel with the palm and a motor 75 for driving the index finger mechanism 63 in parallel with the palm are arranged on the third plane, and for the middle finger. Middle finger motors 79 and 80 for driving the finger mechanism 64 are arranged.
Each finger mechanism part 62, 63, 64, 65, 66 includes three joint parts 83, 84, 85, two frame parts 86, 87 connected by the joint parts 93, 84, 85, and one fingertip part. 88. Each joint 83, 84, 85 is driven by the corresponding motor.

  In the robot hand having such a structure, the pressure sensor 1 or the pressure sensor 2 of the present invention is attached to the frame parts 86 and 87 and the fingertip parts 88 of the finger mechanism parts 62, 63, 64, 65 and 66. Thus, it is possible to smoothly grip various objects having different hardness, material, shape and the like.

  Further, even when the pressure-sensitive sensor 2 is mounted on the fingertip portion of the robot hand having such a structure and the handle of the teacup is gripped, the same performance as the repeatability described above can be exhibited.

  The pressure sensor of the present invention can be used by being attached to a finger mechanism unit of a robot hand that holds an object with a plurality of finger mechanism units.

(A) is the top view which looked at the flexible pressure-sensitive sensor which is an example of this embodiment from the top as a flat state, (b) is the same side view. It is the top view which looked at the flexible pressure-sensitive sensor which is another example of this embodiment from the top as a flat state. (A) is a perspective view which shows the state which has arrange | positioned the pressure sensor of this embodiment on a cylindrical base material, (b) is sectional drawing which follows the AA line in the figure (a). It is sectional drawing which cut | disconnected the pressure-sensitive sensor of this embodiment arrange | positioned on the surrounding side surface of a cylindrical base material along the BB line in FIG. A state where pressure is not applied, (b) shows a state where pressure is applied at one point on the parallel electrode located at the center. It is a cylindrical axial direction sectional view in the state where the pressure sensitive sensor of the conventional structure which pasted conductive pressure sensitive rubber and protective film with the adhesive was arranged on the peripheral side of a cylindrical base material, and (a) is not pressurized The state (b) shows a state where pressure is applied at one point on the parallel electrode located at the center. It is the top view which looked at the flexible pressure-sensitive sensor as a comparative example from the top as a flat state. It is the top view which looked at the robot hand from the back side of the hand. It is the side view which looked at the robot hand from the thumb side. It is the side view which looked at the robot hand from the little finger side. It is the bottom view which looked at the robot hand from the palm side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Pressure sensor 11 Electrode board 11a Parallel electrode 12 Conductive pressure sensitive rubber 12a Long side 12b End part 13 Protection film 13a End part 51 Cylindrical base material

Claims (2)

A pressure-sensitive sensor in which a conductive pressure-sensitive rubber is disposed on a flexible electrode substrate,
The conductive pressure-sensitive rubber is formed in a strip shape, and the conductive pressure-sensitive rubber has a long side coinciding with a direction in which the curvature of the electrode substrate is small and along a direction in which the curvature of the electrode substrate is large. A plurality of conductive pressure-sensitive rubbers arranged at regular intervals, the short sides of the conductive pressure-sensitive rubber arranged in this way are bonded and fixed to the electrode substrate, and at least a part of the long sides of the conductive pressure-sensitive rubber is A pressure-sensitive sensor, which is not bonded and fixed to the electrode substrate. The sensation according to claim 1, wherein a flexible protective film is disposed on the conductive pressure-sensitive rubber so as to have a slack, and an end portion of the protective film is bonded and fixed to the electrode substrate. Pressure sensor.

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