JPH0660856B2 - Pressure sensor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure sensor, and more particularly to a pressure sensor that is mounted on a hand of a robot or the like and is suitable for detecting a force received from a grasped object.

[Prior Art] Many conventional robots, such as manipulators, sequence-type robots, and playback-type robots, work in a fixed place, and thus their working range and functions are limited. For example, a welding robot for the vehicle industry is installed at a specific place on a production line and welds a vehicle body by moving a welding arm. The robot itself does not perform welding on its own judgment.

Recently, however, so-called intelligent robots having sensory and cognitive functions equivalent to the human five senses have been developed and are being put to practical use, and we believe that bipedal robots will be put to practical use in the near future. To be

By the way, these intelligent robots need to be equipped with sensors for detecting various sensations. Typical sensors are a visual sensor and a pressure sensor (tactile sensor), and in particular, the pressure sensor can be said to be indispensable for work such as grasping and grasping an object.

Note that the following items can be listed as performance specifications required for such a pressure sensor for an intelligent robot.

(1) High sensitivity: Sensitivity to detect force is high, for example, load of several grams can be detected.

(2) High resolution: High density.

(3) Wide dynamic range: The operating range is as wide as possible.

(4) High reliability and durability: To withstand harsh environments.

(5) Linearity and little hysteresis: Pressure and output are proportional and there is little hysteresis.

(6) Response speed: The response speed of signal processing is fast.

(7) Flexibility: The flexibility is maintained like the skin of a human hand.

(8) Slip feeling: Not only pressure but also slippage can be detected if possible.

(9) Small size and low cost: Thin, small size and low manufacturing cost / material cost.

Therefore, pressure sensors satisfying some of these requirements have been proposed or put into practical use, for example, those utilizing on / off of a microswitch or a pressure sensitive rubber sheet (conductive rubber sheet). There is a thing or a thing which utilizes the change of the reflection amount of light.

[Problems to be Solved by the Invention] However, the one utilizing the on / off of the microswitch is such that the sensor, which is normally in the “off” state, turns into the “on” state when a force is applied, This only detects the presence or absence of force, and is not suitable for continuously detecting the magnitude of the force.

Further, the one using a pressure sensitive rubber sheet utilizes one in which one conductive rubber sheet is sandwiched between two electrodes and the sheet resistance is changed by applying a force to the electrodes, but the linearity is There is a problem that hysteresis is not easily obtained, and heat resistance is low.

Furthermore, in the case of utilizing the change in the reflection amount of light, a transparent acrylic plate is coated with a rubber sheet having a large number of conical projections, and a mirror body or a light receiving element is arranged on the back surface of the acrylic plate. Then, when the acrylic plate is irradiated with light from the lateral direction of the acrylic plate, the projection of the rubber sheet changes according to the magnitude of the external force, and therefore the degree of dent is detected by the mirror body or the light receiving element. . However, it is difficult for the pressure sensor that utilizes the reflection of this light to know the absolute value of the external force accurately, and there is a problem that the detection accuracy is poor.

In addition to the above-mentioned pressure sensors, various types of pressure sensors have been proposed or prototyped, but none of them have sufficiently satisfied the above performance specifications, and therefore have high sensitivity and are truly practical. There is a strong demand for the development of a pressure sensor with high performance.

The present invention has been made in view of the above problems, and an object thereof is to provide a pressure sensor that has high practical performance, has a simple structure, is easy to manufacture, and can be thinly and densely arranged.

[Means for Solving the Problems] In order to achieve such an object, the present invention has a bridge circuit incorporating a semiconductor strain gauge, a switch means and a surface on which various terminals are arranged as a lower side. A plurality of rectangular silicon cells whose both ends are supported by the support portion of the window form part, and a support base in which the window form part is formed in a matrix,
A ceramic multi-layer wiring board that has electrodes arranged at positions facing the individual terminals of a plurality of rectangular silicon cells arranged in the row direction or column direction on the support base and is attached to the lower surface side of the support base. And, it is fitted in the window form part of the support base,
An anisotropic conductive rubber sheet elastically held between the rectangular silicon cell and the multilayer wiring board and capable of electrically conducting between each terminal and an electrode arranged at a position opposite to the terminal is provided. The load applied from above the rectangular silicon cell is detected.

[Operation] According to the present invention, both ends of the rectangular silicon cell are supported by the respective supporting portions of the supporting base having the window frame portion in a matrix shape, and the semiconductor strain gauge of the silicon cell, the switch means and the solder. A multilayer ceramic wiring board having electrodes on the lower surface side where the terminals of the bumps are formed is provided opposite to the terminals, is attached to the lower surface of the support base, and is fitted into the window form part to form a silicon cell and a multilayer ceramic. Since an anisotropic conductive rubber sheet elastically held between the wiring board and the terminals enables electrical continuity between the terminals and the electrodes, a gap between the silicon cell and the ceramic multilayer wiring board can be obtained. It is possible to maintain a reliable and orderly electrical connection, and when a load is applied from the top side of the silicon cell, strain gauges are generated according to the bending of each silicon cell. The change in resistance can be taken out from the silicon cell individually through the anisotropic conductive rubber sheet and the ceramic multilayer wiring board, and the elasticity of the anisotropic conductive rubber sheet keeps the bending of the silicon cell elastic. As a result, it is possible to provide a pressure sensor with high practicality, which prevents damage to the silicon cell, has a simple structure, is thin, and has high density and high accuracy.

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

First, the principle of bending of a silicon cell according to the present invention, which is a support beam for both ends, will be described with reference to FIGS. 1A and 1B. Now, both ends of the silicon cell 1 are supported by a supporting member 2 as shown in FIG. 1A. If a force is applied to the central portion of the upper surface of the silicon cell 1 in the above state, tensile stress is generated on the lower surface side of the silicon cell 1 as shown in FIG. 1B.

Therefore, on the lower surface side of the silicon cell 1 as described above,
As shown in Fig. 2A and Fig. 2B, four strain gauges R ₁ , R ₂ , R ₃
And R ₄ are arranged, and these strain gauges R _{1 to} R ₄ are connected to the second C
Installed in the bridge circuit as shown in the figure
By applying the voltage V to one of the vertices of the set and grounding one end thereof, and arranging the switching elements S1 and S2 on each of the output lines drawn from the other vertices, the strain gauges R ₁ to The resistance change generated in R _{4 due} to the above-mentioned bending can be taken out as an output signal from the terminals T and t by turning on the switching elements S1 and S2.

FIG. 2A shows that a silicon cell 1 is thus formed of a semiconductor silicon material, on which strain gauges R _{1 to} R ₄ and switching elements S (S1, S2) are provided on the output line from the bridge circuit, , Various terminals, that is, output terminals T and t, switch signal terminals _SWA , _SWB , ground terminal G, and voltage terminal V, solder bumps are provided. In FIG. 2B, the solder bump is indicated by 3, and in FIG. 2A, it is indicated by adding (3) according to various terminals. The reason for using a semiconductor silicon that the beam member is consistent strain gauges R ₁ to R ₄ and the switching elements S (S1, S2) and wiring and the solder bump 3 by the wafer process, if the semiconductor silicon Because it can be formed in the processing step of the film forming technique. Furthermore, by forming such a silicon cell, the beam member can be made smaller and thinner. The switching elements S1 and S2 formed here are
For example, a field effect transistor FET.

FIG. 3 is a diagram showing a basic configuration of the present invention, in which:
Reference numeral 12 denotes a support base. The support base 12 has a window form part 13 and support parts 14 supporting both ends of the silicon cell 1 fitted therein, and is made of an insulating material. Reference numeral 15 denotes a ceramic multi-layer wiring board that is adhered to the support base 12 and strongly holds the support base 12. By forming the multi-layer wiring board 15, the output signal lines from the plurality of silicon cells 1 are appropriately arranged as will be described later. Can be installed and the signal can be taken out.

An anisotropic conductive rubber sheet 16 is fitted in the window frame 13 to provide electrical connection between the silicon cell 1 and the multilayer wiring board 15 and to respond to the bending of the silicon cell 1 due to its own elasticity. Is. The window frame 13 is formed in a grid pattern in the row and column directions of the support 12, and the anisotropic conductive rubber sheet 16 is fitted into each of the window frames 13. The anisotropic conductive rubber sheet 16 has anisotropy by the fibers made of a good electrical conductor such as silver being regularly embedded in the thickness direction of the rubber sheet, so that electrical conduction can be obtained only in the thickness direction. At the same time, the deformation in the thickness direction can be elastically absorbed.

Reference numeral 17 is an electrode formed on the upper layer portion of the multilayer wiring board 15, and these electrodes 17 are formed at the positions facing the solder bumps 3 formed on the lower surface side of the silicon cell 1, and are formed as shown in the figure. By sandwiching the anisotropic conductive rubber sheet 16 between the wiring board 15 and the silicon cell 1, electrical conduction can be obtained between the solder bump 3 and the electrode 17 via the conductive portion 18. Reference numeral 19 denotes a flexible film member that covers the entire surface of the support base 12 in which the silicon cell 1 is housed so as to prevent a grasped object from directly touching the silicon cell 1 and protects the whole.

Next, the overall structure of the pressure sensor having such a configuration and its manufacturing process will be described with reference to FIGS. 4A to 4E.

This embodiment is an example of forming a sensor unit by arranging the silicon cells 1 in 4 rows × 3 columns as shown in FIG. 4D, and the support base 12 thereof is as shown in FIG. 4A. Individual window form parts 13 and support parts 14 are formed. Such a support 12 is first adhesively fixed on the multilayer wiring board 15. Fourth A
In the figure, 20 is a lead wire connected to each electrode 17 of the multilayer wiring board 15 and led out therefrom. The lead-out of these lead wires 20 will be described later.

Next, as shown in FIG. 4B, the anisotropic conductive rubber sheet 16 is fitted into the window frame portion 13. In this case, the vertical and horizontal sizes of the anisotropic conductive rubber sheet 16 are somewhat smaller than the size of the lower window form 13 from the supporting portion 14, and the height of the anisotropic conductive rubber sheet 16 is equal to that of the supporting portion 14. The same degree or a degree of protrusion from the support portion 14 to the upper portion. Then, place the silicon cell 1 on it at the 4th C
By fitting the members as shown in the figure and bringing them into the state shown in the overall view of FIG. 4D, the coating member 19 is attached to the entire surface thereof to form a sensor unit having a configuration as shown in FIG. 4E.

FIGS. 5A to 5C show wiring patterns in each layer of the ceramic multilayer wiring substrate 15, and this example shows an example of electrodes and wiring patterns formed corresponding to four silicon cells 1 in one row. . That is, FIG. 5A shows the surface layer 15 thereof.
Shows the pattern in A , where ,,, and _Are electrodes 17 provided corresponding to the individual terminals V, G, T, t, _SWA and _SWB (see FIG. 2A) of the silicon cell 1 arranged at the opposite positions, and in this case, the switch One of the electrodes for common is a common electrode The other is a unique switch electrode It is said that.

Further, FIG. 5B shows a pattern on the first layer 15B of the multilayer wiring board 15, and FIG. 5C shows a pattern on the second layer 15C thereof. Land connected through a hall
Also, what is enclosed by double circles with the same reference numeral is a through hole land 22 provided in the first layer 15B for pulling down from the surface layer 15A to the second layer 15C .

Thus, in the first layer 15B thereof, the switch common electrode The wiring LS _WC for the power supply, the wiring LV for the power supply and the ground wiring LG are connected as shown in FIG. 5B and formed so as to be taken out in the vertical direction, while the electrode for the output is formed. And switch selection electrode From the output wirings LT _{1 to} L as shown in Fig. 5C.
T ₄ , Lt _{1 to} Lt ₄ , and LS _{W1 to} LS _W4 are wired in the horizontal direction and taken out.

FIGS. 6A, 6B, and 6C show the entire pattern thus formed in each layer of the multilayer wiring board 15, and FIG. 6A shows the electrodes 17 disposed on the entire surface layer 15A . FIG. 6B is a pattern of lands 21 and 22 arranged on the first layer 15B and a lead wire 20 drawn from these,
FIG. 6C shows the patterns of the lead wires 20 that have been pulled down to the lands 21 of the second layer 15C through the through holes and that are laterally pulled out from these lands 21.
Thus, when the sensor unit is composed of the silicon cells 1 of 4 rows and 3 columns as in this example, 3 × 3 extraction lines are formed in the column direction, that is, in the vertical direction, and in the row direction.
That is, a 3 × 4 lead-out line is drawn out from the lateral direction.

In the pressure sensor configured in this manner, for example, the common switch wiring LS _WC in the set of cells arranged in a line in the vertical direction is set to the “ON” state, and then the LS _W1
By sequentially turning "-LS _W4 " on and off, the output signals from the individual cells in this column can be taken in that order.

[Effects of the Invention] As described above, according to the present invention, both ends of the surface on which a bridge circuit incorporating a semiconductor strain gauge, its switch means, and various terminals are supported by a window form part. And a plurality of rectangular silicon cells supported by the parts, a support base on which the window frame parts are formed in a matrix, and individual terminals of the silicon cells arranged in the row and column directions of the support base. In a pressure sensor having an electrode at a position to be provided and a ceramic multilayer wiring board attached to the lower surface side of a support, in order to obtain electrical conduction between the silicon cell and the multilayer wiring board, Since an anisotropic conductive rubber sheet that is elastically held between the two is provided, there is no need to use solder for electrical connection between the silicon cell terminals and the multilayer wiring board, and assembly is possible. Content It is easy to make the whole thin and compact, and it is possible to maintain highly accurate detection sensitivity, and because each silicon cell is elastically supported by the anisotropic conductive rubber sheet, the silicon cell is The effect of preventing breakage can be obtained, and it is possible to provide a pressure sensor suitable for being attached to a robot hand and performing work requiring a high degree of technology.

[Brief description of drawings]

1A and 1B are explanatory views of the principle of detecting a load by a silicon cell supported by a supporting member, and FIGS. 2A and 2B are a plan view and a side view schematically showing a silicon cell simple substance according to the present invention. Fig. 2C is a block diagram of the bridge circuit on the silicon cell, Fig. 3 is a sectional view of the pressure sensor of the present invention, Figs. 4A to 4E are perspective views showing the assembling sequence thereof, and Fig. 5A to Fig. 5A. FIG. 5C is a wiring diagram for each layer of the multilayer wiring board of the pressure sensor according to the present invention, and FIGS. 6A to 6C are wiring diagrams for each layer of the multilayer wiring board in one unit. 1 ... silicon cell, 3 ... solder bumps, S1, S2 ... the switching _{element, R 1, R 2, R} 3, R 4 ... strain _{gauges, T, t, S WA,} S WB, V, G ... terminal, 12 ... Support base, 13 ... Window form part, 14 ... Support part, 15 ... Multilayer wiring board, 15A ... Surface layer, 15B ... First layer, 15C ... Second layer, 16 ... Anisotropic conductive rubber sheet, 17 ... Electrode , 18 ... Conductive part, 19 ... Film member, 20 ... Lead wire, 21, 22 ... Land.

Claims (1)

[Claims] 1. A bridge circuit incorporating a semiconductor strain gauge,
A plurality of rectangular silicon cells, both ends of which are supported by supporting portions of the window form part, with the surface on which the switch means and various terminals are disposed facing down, and the window form part formed in a matrix. A support base and electrodes arranged at positions facing the respective terminals of the plurality of rectangular silicon cells arranged in the row direction or the column direction on the support base, and the lower surface side of the support base. A multilayer wiring board made of ceramic attached to the window frame of the support, and elastically held between the rectangular silicon cell and the multilayer wiring board,
An anisotropic conductive rubber sheet capable of electrical conduction is provided between each of the terminals and the electrodes arranged at positions facing each other, so as to detect a load applied from above the rectangular silicon cell. A pressure sensor characterized in that