JPH0475452B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a pressure-sensitive sensor that is small in size and has high detection accuracy.

[Background technology]

FIG. 1 shows a cross-sectional view of the configuration of a conventional pressure-sensitive sensor. 10 is a pressure-receiving part made of a thin film such as a polyester film on one side (the surface that does not come into direct contact with the external pressure F) by vapor-depositing aluminum or the like as a reflective surface, and 20 is an elastic body made of silicone rubber or the like with good light transmittance. be. 40a, 40b, 40c are light receiving elements;
Reference numeral 50 denotes a transparent glass substrate that transmits light, and 30 refers to a glass substrate on which a non-transparent metal is deposited on one side (hereinafter referred to as a light shielding layer). (referred to as window) 60a, 60
b, 60c. 70 is a layer of air, 80a,
80b and 80c are light emitting elements; 90 is a light emitting element 80
This is a substrate made of ceramic or the like on which components a, 80b, and 80c are mounted. FIG. 2 shows light receiving elements 40a, 40b, 4.
The shape of 0c viewed from the top (external pressure F side) is shown. Moreover, the light transmission windows 60a, 60b, 60c and the light emitting elements 80a, 80b, 80c are approximately circular.

In addition, in FIG. 1, the light receiving and emitting elements 40a to 80
The electrode parts a to c and the supporting parts of each part are omitted, and the receiving and emitting elements are originally arranged in a matrix-like multi-element arrangement, but they are omitted to three elements each, and the driving part and the supporting part of the receiving and emitting elements are omitted. Electric circuit systems such as a control unit are also omitted.

In operation, when the light emitting element 80a is turned on by electrically driving it, the light emitting element 80a
The light emitted from the light transmitting window 60a→glass substrate 50→
Elastic body 20 → Pressure receiving part (reflection part) 10 → Elastic body 20
→The light receiving element 40a, and the light intensity at the light receiving element 40a changes as shown in FIG. 3 depending on the distance between the light receiving element 40a and the pressure receiving part 10. This distance is the external force F
corresponds to the amount of strain (compression) of the elastic body 20 due to the intensity of the force pushing the pressure receiving part 10, so the light receiving element output value can be converted into a pressure value. Light emitting element 80a→
80b → 80c are sequentially driven, and the light receiving element is also 4.
By detecting output values corresponding to the driving of the light emitting elements in the order of 0a → 40b → 40c and converting them into pressure, pressure at multiple points can be detected.

The above is the principle of the pressure sensor, but this configuration includes several problems. The problems are listed below.

(1) Generally, a light emitting diode or the like is used as a light emitting element, but since it does not have much directivity, the amount of light that passes through the light transmission window is small. On the other hand, it is preferable to increase the amount of light to the light receiving element and increase the S/N ratio.
For this purpose, if the diameter of the light transmission window is increased, light will directly enter from the back surface of the light receiving element, as shown in FIG. 4a.

(2) In addition to the light reflected by the reflective surface being incident on the surface of the light receiving element, as shown in FIG. 4b, the glass substrate 50
The light is incident again into the light-shielding layer 30, and is then reflected from the back surface of the light-receiving element 40a.

(3) Depending on the arrangement of other parts, see Figure 4c.
As shown in FIG. 2, the light is reflected by the surface of the glass substrate 50, then reflected by the light shielding layer 30, and enters the light receiving element from the back surface.

Items (1) and (3) above are related to restrictions on the configuration, and there are large restrictions on the placement of each element, etc. For the reason of item (1), increasing the light transmission window diameter will also reduce the inner and outer diameters of the light receiving element. It is difficult to arrange multiple elements at a high density because it needs to be large, and item (3) is related to the angle of incidence of light on the surface of the glass substrate and requires positional accuracy of the light emitting element, which poses a manufacturing problem. In addition, item (2) is one of the major causes of deterioration of the sensor characteristics shown in Figure 3.
This has had an adverse effect, such as not allowing a large change in the output of the light receiving element with respect to a change in the distance between the light receiving element surface and the reflecting surface.

[Problem of invention]

In order to eliminate these drawbacks, the present invention disposes the light shielding layer on the opposite side of the glass substrate, and will be described in detail below.

[Summary of the Invention] A pressure-sensitive sensor of the present invention includes: a light-transmitting elastic body that is elastically deformed by external pressure and has a light-reflecting surface on one surface; a light-transmitting substrate; and a conductive member, and a light-shielding layer formed on one side of the light-transmitting substrate to form a plurality of substantially circular light-transmitting windows that transmit light; and a light-shielding layer having a thickness of less than 10 μm and formed on the light-shielding layer. a light-transmissive electrical insulating layer having a diameter greater than or equal to the diameter of each light-transmitting window of the light-blocking layer, and facing each light-transmitting window of the light-blocking layer at a distance from each other; a plurality of substantially annular light-receiving elements arranged on an insulating layer and each having a light-transmitting window formed in the center thereof; disposed so as to be in contact with a local surface of the light-transmitting elastic body through the electrically insulating layer, and further on a surface of another substrate disposed opposite to the other surface of the light-transmissive substrate. a plurality of approximately circular light emitting elements each having a central axis of light emission approximately on the central axis of each of the light receiving elements mounted and projected onto the surface; and an electric circuit that drives each of the light emitting elements and each of the light receiving elements. and the other substrate is arranged at a distance from the light shielding layer so that light from the light emitting element does not directly enter the back surface of the light emitting element.

[Embodiment] FIG. 5 shows a first embodiment of the present invention, and shows a cross-sectional view only of the periphery of one set of light receiving and emitting elements. Chromium (or nichrome) is deposited on the upper surface (light receiving element side) of the glass substrate 50 using a vacuum evaporation method, and is made of a conductive material and has a plurality of approximately circular light transmitting windows (indicated by thick lines in FIG. 5) that transmit light. A substantially circular light-shielding layer 30 is formed on one surface of the light-transmissive substrate so as to provide a thin line portion on the glass substrate 50 shown in FIG. Furthermore, in order to electrically insulate between the light-shielding layer 30 and the light-receiving element 40a, a light-transmitting insulating layer 100 is formed using a silicon (or alumina) oxide using a sputtering method (or glow discharge method). After forming on the insulating layer 100, a plurality of light receiving elements 40a are further formed on the insulating layer 100 at intervals so as to face each light transmitting window of the light shielding layer 30 by a sputtering method or the like. In this case, a light transmitting window (the thin line between the light receiving elements 40a indicated by thick lines in FIG. 5) is formed in the center of each light receiving element 40a. As shown in
It has a diameter larger than the diameter of each light-transmitting window of the light-shielding layer, and the substantially central axis of each light-receiving element 40a substantially coincides with the central axis of the light-emitting element 80a, and as shown by reference numeral 40 in FIG. It forms a circular ring.
Since the thickness of the insulating layer 100 is sufficiently thin compared to the thickness of the glass substrate (in this example, the thickness of the glass substrate is about 1 mm and the thickness of the insulating layer is less than 10 μm), it is different from the conventional one. , a light shielding layer 30 directly below the light receiving element.
This is almost equivalent to having a light-receiving element, and there is almost no light incident from the bottom surface of the light-receiving element as in the conventional example.

FIG. 6 is a perspective view showing a schematic configuration of the pressure-sensitive sensor of this embodiment. In the figure, the receiving and emitting elements are each 4×4.
This is an example in which elements are arranged at 2 mm intervals. In the embodiment, the pressure receiving part 10 is made of a thin film several tens of microns thick, the elastic body 20 is made of transparent silicone rubber 2 mm thick, and the electric circuit part is not shown. Each light receiving element 40
The light emitting elements 80 and 80 are each driven in a matrix manner, and the light receiving element 40 is made of amorphous silicon.

FIG. 7 shows a block diagram of the electric circuit system. 20
0 is a light receiving element group and its matrix drive unit, 21
0 is a light emitting element group and its matrix driving unit, 220
is an analog multiplexer, 230 is an amplifier, 2
40 is an A/D converter, 250 is a ROM (Read
The output signal of the A/D converter 240 is connected to the address signal of the ROM 250 (Only Memeory), and the output data of the ROM is sent to the outside from the external output terminal 270 through the interface section 260. 300 is a control section. The operation begins by selecting the matrix 210 to light one light emitting element in the light emitting element group using a signal from the control unit 300, and then outputting the output of its paired light receiving element (the light receiving element located directly above the lit light emitting element) into the matrix. 200 and an analog multiplexer 220.
Specify and select by 00. The output of analog multiplexer 220 is amplified by amplifier 230,
The A/D converter 240 converts it into a digital quantity. This digital value corresponds to the distance between the light receiving element and the reflecting surface in Figure 3, so it is stored in the ROM25.
Convert to pressure value using 0. The ROM 250 has a built-in table in advance that represents the relationship between distance and pressure based on the relationship between the strain rate and the pressure of the elastic body 20 (including the pressure receiving part 10). The converted pressure value is then sent out from the external output terminal 270 via the interface section 260. In addition, the elastic body 20 is subjected to force and distortion, but when the force is removed, it almost returns to its original position within several hundred milliseconds.
Needless to say, the next pressure can be detected again. It goes without saying that the glass substrate 50 used in this embodiment may be made of optically transparent quartz, plastic, or the like.

〔Effect of the invention〕

In this example, the light receiving element and the light shielding layer are formed on the same surface of the light receiving element mounting board with a thin insulator (light transmitting) in between, thereby eliminating the problem of light incident from the back side of the sensor, which was a drawback of the conventional example. In addition to improving the measurement accuracy of pressure-sensitive sensors that use light, it also increases the degree of freedom in configuration (for example, the size of each element), making it possible to reduce the positional accuracy of the light-receiving element and light-emitting element during manufacturing compared to conventional methods. Deterioration in performance can be kept to a minimum, and the manufacturing process can be simplified.

Since the present invention optically measures the amount of strain in an elastic body using light receiving and emitting elements, it is possible to detect pressure at multiple points with high density, and it can be applied to a tactile sensor by being mounted on a robot hand or the like.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing the configuration of a conventional pressure-sensitive sensor, Figure 2 is a plan view showing the shape and arrangement of the light-receiving element on the substrate, Figure 3 is a diagram showing the output characteristics of the light-receiving element, and Figure 4. a to c are diagrams showing the light incident path from the back surface of a light receiving element in a conventional example, FIG. 5 is a cross-sectional view of a sensor configuration in an embodiment of the present invention, and FIG. 6 is a perspective view of a sensor configuration in an embodiment of the present invention. , FIG. 7 is a block diagram of an electric circuit system in an embodiment of the present invention. 10... Pressure receiving part, 20... Elastic body, 30... Light shielding layer, 40, 40a, 40b, 40c... Light receiving element, 50... Light receiving element mounting substrate, 60a, 60
b, 60c...light transmission window, 70...air layer, 8
0, 80a, 80b, 80c... light emitting element, 90
...Light emitting element mounting substrate, 100...Insulating layer, 2
00... Light receiving element group and matrix drive unit, 210
...Light emitting element group and matrix drive unit, 220...
Analog multiplexer, 230...Amplifier, 2
40...A/D converter, 250...ROM, 26
0...Interface unit, 300...Control unit.

Claims (1)

[Claims] 1. A light-transmitting elastic body that is elastically deformed by external pressure and has a light-reflecting surface on one surface, a light-transmitting substrate, and a conductive member, and having a substantially circular shape that transmits light. a light-shielding layer formed on one side of the light-transmitting substrate to form a plurality of light-transmitting windows; and a light-transmissive electric layer having a thickness of less than 10 μm and formed on the light-shielding layer. an electrically insulating layer having a diameter greater than or equal to the diameter of each light-transmitting window of the light-blocking layer, and arranged on the electrically-insulating layer so as to face each light-transmitting window of the light-blocking layer at a distance from each other; and a plurality of substantially annular light-receiving elements each having a light-transmitting window formed in the center thereof, and the light-transmitting substrate includes the electrically insulating layer in the light-receiving element and the light-transmitting window portion. disposed so as to be in contact with a local surface of the light-transmissive elastic body through the substrate, and further mounted on a surface of another substrate disposed opposite to the other surface of the light-transmissive substrate, and placed on the surface of the other substrate. a plurality of approximately circular light emitting elements each having a central axis of light emission approximately on the central axis of each of the light receiving elements projected on the light receiving element; and an electric circuit for driving each of the light emitting elements and each of the light receiving elements; A pressure-sensitive sensor characterized in that the substrate is placed at a distance from the light-shielding layer so that light from the light-emitting element does not directly enter the back surface of the light-emitting element.