JP2023098377A - Pressure sensitive sensor - Google Patents

Abstract

To provide a pressure sensitive sensor that can achieve a reduction in thickness and the number of components, and avoids the possibility that displacement between constituents occurs due to assembly.SOLUTION: A plurality of contact patterns 21, 51 and a plurality of wiring patterns 31, 61 connected with the contact patterns 21, 51, respectively, are formed on a substrate 10. A pressure-sensitive resistor 41 in which the value of resistance changes according to pressure is formed on the plurality of contact patterns 21, 51. A pattern 71 for conduction between contacts for establishing conduction between the plurality of contact patterns 21, 51 with the pressure-sensitive resistor 41 therebetween is formed at a position on the pressure-sensitive resistor 41 opposite to the plurality of contact patterns 21, 51, thereby constituting a pressure sensitive sensor 1-1.SELECTED DRAWING: Figure 1

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure sensor whose resistance value changes according to pressing force.

2. Description of the Related Art Conventionally, a pressure-sensitive sensor whose resistance value changes according to a pressing force is disclosed, for example, in Patent Document 1, in which a lower circuit board provided with a lower electrode and an upper circuit board provided with an upper electrode are separated from each other by a spacer. At this time, the upper electrode and the lower electrode are opposed to each other in the opening provided in the spacer, and the upper electrode is lowered by pressing the upper circuit board on the back side of the upper electrode and lowering it. It is configured to contact the side electrode and change the resistance value between the upper electrode and the lower electrode according to the magnitude (contact area) of the contact force (load).

JP 2017-45629 A

However, since the conventional pressure-sensitive sensor is composed of two circuit boards and spacers, as described above, the number of parts increases, the thickness of the product increases, and two circuit boards and spacers are required. There is a possibility that the positions of the opening of the spacer and the upper electrode may be displaced with respect to the lower electrode due to displacement of the spacer during assembly.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pressure-sensitive sensor that can reduce the number of parts and reduce the thickness of the components, and eliminates the risk of misalignment between components due to assembly. That's what it is.

According to the present invention, in a pressure-sensitive sensor whose resistance value changes according to a pressing force, a plurality of contact patterns and a plurality of wiring patterns connected to each of the contact patterns are formed on a substrate, and a plurality of wiring patterns are formed on the contact patterns. a pressure-sensitive resistor whose resistance value changes according to pressure is formed, and the pressure-sensitive resistor is formed between the plurality of contact patterns at a position facing the plurality of contact patterns on the pressure-sensitive resistor. It is characterized by forming an inter-contact conduction pattern for intervening and conducting.
The number of contact patterns may be any number as long as it is two or more.
According to the present invention, a pressure sensor can be constructed by forming various patterns on a single substrate. There is no risk of misalignment due to assembly between the contact-to-contact conduction patterns.
In addition, since spaces such as spacers are not provided between a plurality of contact patterns as in the prior art, the resistance value starts to change simply by applying a light force. Therefore, it is suitable for use as a pressure-sensitive sensor that requires a characteristic in which the resistance value starts to change with a light force and the resistance value further changes as the pressing force increases.
In addition, since the electric circuit of this pressure-sensitive sensor has a structure in which two resistors (thickness thereof) are connected in series, the resistance value of the pressure-sensitive resistor can be easily increased. It is possible to obtain a pressure-sensitive sensor with high resolution.
In addition, since the thickness of the pressure-sensitive resistor is thin, the multiple contact patterns and the pattern for conduction between contacts are electrically connected only in the parts that face each other vertically (just above and below) through the pressure-sensitive resistor (resistor The resistance value can be easily adjusted by adjusting the area and shape of each contact pattern, contact conduction pattern, and pressure-sensitive resistor (for example, the contact pattern and the contact conduction pattern facing each other). The smaller the area, the larger the resistance).

In addition to the above features, the present invention is characterized in that the pressure-sensitive resistor is formed so as to cover at least part of the periphery of the plurality of contact patterns.
The pressure-sensitive resistor does not need to cover the entire top surface of the plurality of contact patterns, and may be configured by covering a portion of the top surface.

Further, in addition to the above features, the present invention is characterized in that the plurality of contact patterns, the plurality of wiring patterns, the pressure-sensitive resistors, and the inter-contact conduction pattern are laminated on the substrate by printing. It is characterized by having
As a result, various patterns can be easily and accurately formed on a single substrate, and the number of parts, manufacturing cost, and thickness can be reduced. In addition, there is no risk of misalignment due to assembly between a plurality of contact patterns, pressure-sensitive resistors, and inter-contact conduction patterns.

According to the present invention, the number of parts can be reduced and the thickness can be reduced. In addition, there is no risk of misalignment due to assembly between the contacts, and a pressure sensor with stable product characteristics can be obtained.

1 is a schematic cross-sectional view of a pressure sensor 1-1; FIG. 2 is a schematic plan view of a pressure sensor 1-1; FIG. FIG. 4 is an operation explanatory diagram of the pressure sensor 1-1; 2 is a plan view showing a specific example of a pressure sensor 1-1; FIG. 2 is a schematic cross-sectional view of a pressure sensor 1-2; FIG. 2 is a schematic plan view of a pressure sensor 1-2; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic cross-sectional view (a schematic cross-sectional view taken along line AA in FIG. 2) of the pressure sensor 1-1 according to the first embodiment of the present invention, and FIG. 2 is a schematic plan view of the pressure sensor 1-1. As shown in these figures, the pressure sensor 1-1 has a pair of first and second contact patterns 21 and 51 on the substrate 10 and is connected to the first and second contact patterns 21 and 51, respectively. A pair of first and second wiring patterns 31 and 61 are formed on the first and second contact patterns 21 and 51, and pressure-sensitive resistors (pressure-sensitive resistor layers, A pressure-sensitive resistor pattern 41 is formed, and a pressure-sensitive resistor is formed between the first and second contact patterns 21 and 51 at positions facing the first and second contact patterns 21 and 51 on the pressure-sensitive resistor 41 . It is configured by forming a contact-to-contact conduction pattern 71 for conduction through the body 41 . In the following description, the term "upper" refers to the direction viewed from the substrate 10 toward the surface on which the first and second contact patterns 21 and 51 are formed, and the term "lower" refers to the opposite direction. However, this is not intended to limit the direction in which the pressure sensor 1-1 is used.

Next, the configuration of the pressure sensor 1-1 will be described together with its manufacturing method.
First, the substrate 10 is prepared. The substrate 10 is composed of a flexible synthetic resin film, and in this example, a polyethylene terephthalate (PET) film is used.

Next, the first contact pattern 21 and the first wiring pattern 31, and the second contact pattern 51 and the second wiring pattern 61 are formed on the substrate 10, and a conductive paste (silver paste in this example) is screened. Simultaneously formed by printing. The first and second contact patterns 21 and 51 are both elongated rectangles having the same shape and size, and are spaced apart from each other by a predetermined distance so that their long sides are parallel to each other. The first and second wiring patterns 31 and 61 are linear and connected to the centers of the outer long sides of the first and second contact patterns 21 and 51, respectively. The shapes of the first and second contact patterns 21 and 51 and the first and second wiring patterns 31 and 61 may be other various shapes. The first and second contact patterns 21 and 51 are preferably formed at positions where they can be pressed simultaneously by a pressing body such as a finger.

Next, a pressure-sensitive layer is placed on the substrate 10 so as to cover the entire upper surface of the first and second contact patterns 21 and 51 and part of the first and second wiring patterns 31 and 61 connected thereto. A resistor 41 is formed by screen printing carbon paste. The pressure-sensitive resistor 41 is circular in this example (other various shapes may be used), and is formed with an area larger than the combined area of the first and second contact patterns 21 and 51. . The carbon paste is composed of a synthetic resin that remains flexible even when hardened, a conductive paint that is a mixture of carbon powder and a solvent.

Next, an inter-contact conduction pattern 71 is formed on the upper surface of the pressure-sensitive resistor 41 by screen-printing a silver paste. The inter-contact conduction pattern 71 is circular in this example (other various shapes may be used), and is directly above the first and second contact patterns 21 and 51 via the pressure-sensitive resistor 41. It is formed at a position facing each other, more specifically, at a position covering the entirety of the first and second contact patterns 21 and 51 right thereabove. The inter-contact conduction pattern 71 provides conduction between the first and second contact patterns 21 and 51 via the pressure-sensitive resistor 41 .

The pressure sensor 1-1 is completed by the above manufacturing method. The above-described manufacturing procedure is only an example, and it goes without saying that various other different manufacturing procedures may be used for manufacturing.

As shown in FIG. 3, the pressure-sensitive sensor 1-1 configured as described above is configured such that when a voltage is applied between the first and second wiring patterns 31 and 61, the first wiring pattern 31 ⇔ the first Current flows through the path of contact pattern 21 ⇔ pressure-sensitive resistor 41 ⇔ pattern 71 for conduction between contacts ⇔ pressure-sensitive resistor 41 ⇔ second contact pattern 51 ⇔ second wiring pattern 61 .

That is, the resistance value between the first and second wiring patterns 31 and 61 is equal to Assuming that the resistance value is zero, the resistance value is 2R [Ω], which is twice the resistance value R [Ω] corresponding to the thickness of the pressure-sensitive resistor 41 . At least a portion of the contact-to-contact conduction pattern 71 must be located directly above the first contact pattern 21 and the second contact pattern 51 to conduct with each other. Therefore, at least a portion of the contact-to-contact conduction pattern 71 needs to be positioned right above the first contact pattern 21 and the second contact pattern 51, and this is the embodiment.

When the substrate 10 is placed on a base (not shown) and the contact pattern 71 is pressed from above by a finger or a pressing body such as a key top, the flexible pressure-sensitive resistor 41 is compressed. As the thickness becomes thinner, the carbon particles in the pressure-sensitive resistor 41 come into strong contact with each other, increasing the contact area between the carbon particles. , and the resistance value between the inter-contact conduction pattern 71 and the second contact pattern 51, that is, the resistance value between the first and second contact patterns 21, 51 decreases. On the other hand, if the pressure is released, the thickness of the pressure-sensitive resistor 41 returns to its original thickness due to its elastic restoring force, and the resistance value increases. In other words, the resistance value between the first and second contact patterns 21 and 51 differs according to the magnitude of the pressing force (pressing force), thereby obtaining different outputs according to the pressing force. The magnitude of the pressing force can be detected.

By the way, the larger the resistance value when the pressure-sensitive resistor 41 is not pressed, the greater the range of change in the resistance value when the pressure-sensitive resistor 41 is pressed. In the pressure-sensitive sensor 1-1, as described above, the pressure-sensitive resistor 41 passes twice in series in the electric circuit, so that the resistance value is doubled. The resistance value of the body 41 can be increased, and the pressure sensor 1-1 with high resolution can be obtained.

Of course, in the pressure-sensitive sensor 1-1, it is also preferable to increase the resistance value by forming the pressure-sensitive resistor 41 thicker than the first and second contact patterns 21 and 51. However, the present invention is not limited to this, and the thickness may be the same as or thinner than the thickness of the first and second contact patterns 21 and 51 .

Since the thickness of the pressure-sensitive resistor 1 is thin, it is the first contact pattern 21 in the entire pressure-sensitive resistor 41 (exactly includes a portion of the first wiring pattern 31 connected to it, but omitted in the following description), the portion of the surface where the inter-contact conduction pattern 71 is vertically opposed (overlapping), and the second contact Only the portion of the surface where the pattern 51 (accurately includes a part of the second wiring pattern 61 connected thereto, but is omitted in the following description) and the pattern 71 for conduction between contacts vertically faces (overlaps) is. In this embodiment, the first and second contact patterns 21 and 51 are smaller than the inter-contact conduction pattern 71. Only the piezoresistor 41 portion acts as a resistor. Therefore, when it is desired to obtain a high resistance value, the resistance value can be increased by reducing the area of at least one of the first and second contact patterns 21 and 51 . At this time, the inter-contact conduction pattern 71 is sized to cover a wider range than the portion forming the first and second contact patterns 21 and 51 facing each other. It is preferable to reliably prevent the occurrence of a portion where the inter-contact conduction pattern 71 does not vertically face the patterns 21 and 51 .

That is, since the first and second contact patterns 21 and 51 and the inter-contact conduction pattern 71 are electrically connected only at the portions facing each other vertically (just above and below) via the pressure-sensitive resistor 41 (resistance value ), the resistance value can be easily adjusted by adjusting the area, shape, and arrangement position of the first and second contact patterns 21 and 51, the contact-to-contact conduction pattern 71, and the pressure-sensitive resistor 41. It can be performed.

As described above, the resistance value of the pressure sensor 1-1 is determined by the area of the smaller pattern (first and second contact patterns 21, 51). The pattern to be printed (the first and second contact patterns 21) is formed smaller than the pattern to be printed on the pressure-sensitive resistor 41 (the pattern for conduction between contacts 71) because the substrate 10 with a smooth surface is formed. The patterns (first and second contact patterns 21, 51) formed on the upper surface can have higher printing accuracy than the pattern (inter-contact conduction pattern 71) formed on the pressure-sensitive resistor 41 having a rough surface. This is also because it can be expected that the precision of the resistance value determined by the area of the smaller patterns (first and second contact patterns 21 and 51) can be further improved.

In addition, the pressure-sensitive resistor 41, like this pressure-sensitive sensor 1-1, is formed to have an outer shape larger than the portion forming the first and second contact patterns 21, 51 on the substrate 10, It is preferable to form so as to surely cover the first and second contact patterns 21 and 51 .

FIG. 4 is a plan view showing a specific example of the pressure sensor 1-1. As shown in the figure, the substrate 10 includes a sensor main body forming portion 11 and an output lead-out portion 13 connected to the outer periphery of the sensor main body forming portion 11 and extending in a strip shape. In the sensor main body forming portion 11, there are first and second contact patterns 21 and 51, a pressure-sensitive resistor 41, a pattern 71 for conduction between contacts, and second contacts connected to the first and second contact patterns 21 and 51, respectively. Parts of the first and second wiring patterns 31 and 61 are printed and formed, and the remaining parts of the first and second wiring patterns 31 and 61 are printed and formed on the output lead-out portion 13 and output to their tips. Terminal patterns 33 and 63 are formed by printing. This makes it possible to easily apply a voltage between the first and second contact patterns 21 and 51 and obtain an output.

FIG. 5 is a schematic cross-sectional view (schematic cross-sectional view taken along line BB in FIG. 6) of the pressure sensor 1-2 according to the second embodiment of the present invention, and FIG. 6 is a schematic plan view of the pressure sensor 1-2. In the pressure-sensitive sensor 1-2 shown in these figures, the same reference numerals are given to the same or corresponding parts as the pressure-sensitive sensor 1-1 shown in FIGS. ”). Matters other than those described below are the same as those of the embodiment shown in FIGS.

This pressure sensor 1-2 is different from the pressure sensor 1-1 in that the first and second contact patterns 21-2 and 51-2 are used for conducting between the pressure sensitive resistor 41-2 and the contacts. This point is formed in a size that protrudes from the pattern 71-2. As a result, the pressure-sensitive resistor 41-2 and the inter-contact conduction pattern 71-2 partially cover the periphery (periphery) of the first and second contact patterns 21-2 and 51-2.

That is, the pressure-sensitive resistor 41-2 does not need to cover the entire top surface of the first and second contact patterns 21-2 and 51-2. It may be configured by partially covering the periphery of 51-2. In this manner, the sizes and arrangement positions of the first and second contact patterns 21-2 and 51-2, the pressure-sensitive resistor 41-2, and the inter-contact conduction pattern 71-2 can be changed in various ways. Even if the pressure sensor 1-2 is configured in this manner, the action and effect of the present invention are exhibited.

As described above, the pressure sensor 1-1 (1-2) has a plurality of contact patterns 21, 51 (21-2, 51-2) and each contact pattern on the substrate 10 (10-2). 21, 51 (21-2, 51-2) are formed, and a plurality of contact patterns 21, 51 (21-2, 51-2) are formed. 2) A pressure-sensitive resistor 41 (41-2) whose resistance value changes according to pressure is formed on the pressure-sensitive resistor 41 (41-2), and a plurality of contact patterns 21, 51 (21-2) on the pressure-sensitive resistor 41 (41-2) are formed. , 51-2), the inter-contact conduction pattern 71 for conducting between the plurality of contact patterns 21, 51 (21-2, 51-2) via the pressure sensitive resistor 41 (41-2). (71-2), the pressure sensor 1-1 (1-2) can be configured only by forming various patterns on one substrate 10 (10-2). The number of parts can be reduced and the thickness can be reduced. 2) There is no risk of misalignment due to assembly.

In addition, since spaces such as spacers are not provided between a plurality of contact patterns as in the prior art, the resistance value starts to change simply by applying a light force. Therefore, it is suitable for use as a pressure sensor 1-1 (1-2) that requires characteristics in which the resistance value starts to change with a light force and the resistance value further changes as the pressing force increases. .

Further, the electric circuit of this pressure sensor 1-1 (1-2) is an electric circuit having a structure in which two resistances of the pressure-sensitive resistor 41 (41-2) are connected in series as described above. Therefore, the resistance value of the pressure-sensitive resistor 41 (41-2) can be easily increased, and a pressure-sensitive sensor with high resolution can be obtained.

Further, the first and second contact patterns 21, 51 (21-2, 51-2) and the first and second wiring patterns 31, 61 (31 -2, 61-2), the pressure-sensitive resistor 41 (41-2), and the inter-contact conduction pattern 71 (71-2) are laminated on the substrate 10 (10-2) by printing. Therefore, it can be formed on one substrate 10 (10-2) at an easy and accurate position, and from this point as well, reduction in the number of parts, reduction in manufacturing cost, and reduction in thickness can be achieved. be able to. Further, there is a misalignment due to assembly between the first and second contact patterns 21, 51 (21-2, 51-2), the pressure-sensitive resistor 41 (41-2), and the inter-contact conduction pattern 71 (71-2). there is no danger of it happening.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the technical ideas described in the claims, specification and drawings. It is possible. Any shape, structure, or material that is not directly described in the specification and drawings is within the scope of the technical idea of the present invention as long as it produces the action and effect of the present invention. For example, the substrate 10 (10-2), the first contact pattern 21 (21-2), the first wiring pattern 31 (31-2), the pressure sensitive resistor 41 (41-2), the second contact Needless to say, various changes can be made to the shape and arrangement position of the pattern 51 (51-2), the second wiring pattern 61 (61-2), and the inter-contact conduction pattern 71 (71-2).

In the above examples, screen printing was used to form various patterns, but various other printing methods (such as offset printing and inkjet printing) and various pattern forming methods other than printing (such as etching) may be used. can be Further, in the above embodiments, flexible substrates are used as the substrates 10 and 10-2, but hard substrates may be used.

Also, the number of contact patterns may be three or more. Alternatively, an insulating layer or an insulating film may be separately provided on the contact-to-contact conduction pattern 71, and the pressing body may be pressed from thereon.

Moreover, the embodiments shown in the above description and each drawing can be combined with each other as long as there is no contradiction in the purpose, configuration, and the like. In addition, even if only a part of the above description and the contents of each drawing can be independent embodiments, the embodiment of the present invention is one embodiment in which the above description and each drawing are combined. is not limited to

1-1, 1-2 pressure sensor 10, 10-2 substrate 21, 21-2 first contact pattern 31, 31-2 first wiring pattern 41, 41-2 pressure-sensitive resistor 51, 51-2 Second contact pattern 61, 61-2 Second wiring pattern 71, 71-2 Conductive pattern between contacts

Claims (3)

In a pressure sensor whose resistance value changes according to the pressing force,
Forming a plurality of contact patterns and a plurality of wiring patterns connected to the respective contact patterns on a substrate,
Forming a pressure-sensitive resistor whose resistance value changes according to pressure on the plurality of contact patterns,
An inter-contact conduction pattern for conducting between the plurality of contact patterns via the pressure-sensitive resistor is formed at a position facing the plurality of contact patterns on the pressure-sensitive resistor. pressure sensor. The pressure sensor according to claim 1,
A pressure-sensitive sensor, wherein the pressure-sensitive resistor is formed so as to cover at least part of the periphery of the plurality of contact patterns. The pressure sensor according to claim 1 or 2,
The pressure-sensitive sensor according to claim 1, wherein the plurality of contact patterns, the plurality of wiring patterns, the pressure-sensitive resistors, and the inter-contact conduction pattern are laminated on the substrate by printing.

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