JP6324803B2 - Pressure-sensitive sensor and manufacturing method thereof - Google Patents

Description

  The present invention relates to a pressure-sensitive sensor using a piezoelectric film that generates a voltage by applying pressure and a method for manufacturing the same.

  A pressure-sensitive sensor using a piezoelectric film that generates a voltage in response to an input caused by contact, pressing or sliding of a part of a human body or an object (hereinafter referred to as “pressurization”) is generally applied to both sides of a piezoelectric film. It is used as a laminate in which an electrode is disposed and a plastic film that protects the electrode is laminated. Such a pressure-sensitive sensor detects a pressure input by detecting a potential difference (hereinafter referred to as “voltage”) generated between electrodes facing each other with a piezoelectric film sandwiched by stress and vibration caused by the pressure input. Acts as a sensor.

  As such a pressure-sensitive sensor, for example, in US Pat. No. 6,996,891 (Patent Document 1), a substrate in which an aluminum film forming an electrode pattern is laminated on both sides of a piezoelectric film, the electrode pattern is piezoelectric. A pressure-sensitive sensor (FIG. 1 of Patent Document 1) laminated so as to be on the sensor film side and a manufacturing method thereof are disclosed.

  The pressure-sensitive sensor having the above configuration is manufactured by laminating a substrate on which an electrode pattern is formed and a piezoelectric film coated with an adhesive with a roll-to-roll so that the electrode pattern is disposed on both surfaces of the piezoelectric film. Is disclosed (FIG. 3 of Patent Document 1). From such a manufacturing method, the pressure-sensitive sensor disclosed in Patent Document 1 has a piezoelectric film 1, an electrode 2, and a substrate 3 fixed and integrated with an adhesive 4 as shown in FIG. 1, which is a cross-sectional view cut in the thickness direction. It becomes the composition.

  Japanese Patent Laid-Open No. 2014-22583 (Patent Document 2) discloses a method of punching an electrode pattern into the electrode conductive layer of a laminate in which an electrode conductive layer is laminated on a plastic film serving as a substrate. A manufacturing method is disclosed in which an electrode pattern is created by removing this part, and a substrate provided with the electrode pattern and a piezoelectric film are overlapped or adhered.

  On the other hand, as a pressure-sensitive sensor in which a piezoelectric film and an electrode are not attached, for example, in JP 2013-178241 A (Patent Document 3), a peripheral portion of two substrate films sandwiching a piezoelectric film is used. It is disclosed that the piezoelectric film and the substrate are fixed by sticking (FIG. 6 of Patent Document 3) or screwing the periphery of the piezoelectric film (FIG. 1 of Patent Document 3).

US Pat. No. 6,996,891 JP, 2014-22583, A JP 2013-178241 A

  In the case of a pressure-sensitive sensor in which a substrate, an electrode, and a piezoelectric film are fixed and integrated with an adhesive, since the piezoelectric film is fixed to the substrate and the electrode via an adhesive, the deformation of the piezoelectric film is suppressed, Displacement with respect to the original stress is difficult to obtain, and the adhesive layer absorbs stress and vibration energy caused by the pressure input, so that a voltage having an expected magnitude cannot be generated. This hinders improvement in sensitivity of the pressure sensor.

  On the other hand, the piezoelectric film and the substrate provided with the electrode pattern are fixed to a portion other than an area (hereinafter referred to as “pressure-sensitive area”) such as a peripheral portion of the piezoelectric film that receives pressure input as a pressure-sensitive sensor. According to the method of fixing the peripheral portion of the piezoelectric film and the substrate with a fixing means such as a screw, it is possible to avoid fixing and integrating the substrate, the electrode, and the piezoelectric film.

  In the case of a pressure-sensitive sensor in which an electrode is fixed to a piezoelectric film by fixing only the peripheral edge, etc., for example, when it is applied to a touch panel used in a smartphone or a terminal type image device, an unfixed portion becomes large. Therefore, the gap between the piezoelectric film and the electrode in the pressure-sensitive area and the variation in the contact state become large, and this causes a new problem that stable sensitivity cannot be obtained.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a pressure sensor having high sensitivity and small variation in sensitivity and a method for manufacturing the pressure sensor. There is to do.

As for the pressure-sensitive sensor that employs a method of fixing only the peripheral edge, etc., in particular, the present inventors have conducted various studies on a sensor having a plurality of electrodes in the pressure-sensitive area. It was found that the waveform and size of the voltage signal (time-potential signal) generated when releasing the pressurization (hereinafter referred to as “pressurization input”) differ depending on the position of the electrode. As shown in the schematic cross-sectional view in the thickness direction shown in FIG. 2A, when only the peripheral portion of the piezoelectric film 1 is fixed (fixed by the adhesive 4 in the embodiment of FIG. 2A), the distance between the electrode and the piezoelectric film is likely to change. In addition, since there is variation in the degree of change of the interval for each electrode, as shown in the schematic cross-sectional view in the thickness direction shown in FIG. Such vibrations (FIG. 2B) and standing waves may occur. As a result, the present inventors considered that even with the same pressure input, a voltage signal having a different waveform is generated depending on the pressure position, and thus the generated voltage varies.
In addition, since the substrate having electrodes is not fixed to the piezoelectric film, vibration due to the pressure input is easily propagated through the substrate and the piezoelectric film, and a large voltage is generated not only at the position where the pressure is input but also at the surrounding electrodes. It has also been found that the detection sensitivity of the input position, that is, the resolution is lowered.
In order to reduce the sensitivity variation and improve the resolution while maintaining the high sensitivity of the pressure-sensitive sensor, the present inventors maintain the relative position between the electrode and the piezoelectric film in a portion other than the electrode. The inventors considered that it would be effective to suppress the propagation of vibrations and suppress the voltage generated at a position other than the pressure input position, and studied such means to complete the present invention.

A pressure-sensitive sensor according to an aspect of the present invention includes a piezoelectric film that converts a pressure input into a voltage; and first and second substrates with electrodes on which a plurality of electrodes for taking out the voltage are disposed.
A pressure-sensitive sensor that detects a voltage generated by the force received by the first electrode-attached substrate by sandwiching the piezoelectric film between the first and second electrode-attached substrates,
Between the electrodes disposed on the first electrode-attached substrate, a vibration absorber that absorbs vibrations generated by the pressure input received by the adjacent electrodes is disposed.
A gap is provided between the vibration absorber and an electrode adjacent to the vibration absorber. Or the said vibration absorber is comprised from the base and the vibration absorption main body provided on this base.

  The method for manufacturing a pressure-sensitive sensor according to one aspect of the present invention includes a step of forming an electrode and a pedestal by removing a part of a conductive material stacked on a substrate; and a vibration absorbing main body on the pedestal. Forming a vibration absorber by printing on the substrate; and contacting the piezoelectric film with the substrate on which the vibration absorber and the electrode are formed.

  According to the above invention, it is possible to suppress the generation of a voltage at a position other than the input position. Therefore, it is possible to provide a pressure-sensitive sensor having a high detection sensitivity of the input position and a small variation in the generated voltage.

It is a structure schematic diagram which shows one Embodiment of the conventional pressure sensor. It is a schematic diagram for demonstrating the problem in a pressure sensor. It is a schematic diagram for demonstrating the problem in a pressure sensor. It is a schematic diagram which shows the pressure sensor which concerns on 1st embodiment of this invention. It is a P-P 'cross-sectional schematic diagram of the pressure sensor which concerns on 1st embodiment of this invention. It is a schematic diagram which shows the example of arrangement | positioning pattern of a vibration absorber. It is a schematic diagram which shows the pressure sensor which concerns on 2nd embodiment of this invention. It is a top view schematic diagram of the 1st board | substrate with an electrode used by 2nd embodiment. It is a top view schematic diagram of the 2nd board | substrate with an electrode used by 2nd embodiment. It is a schematic diagram which shows the electrode and base pattern of the measurement sample used in the Example. It is a schematic diagram for demonstrating the electrode number of the measurement sample used in the Example. It is a schematic diagram for demonstrating the measuring method performed in the Example. It is a graph which shows the measurement result of an electrode position and generated voltage. It is a figure which shows the measurement result of a voltage waveform.

  Although embodiments of the present invention will be described below, it should be considered that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

A pressure-sensitive sensor according to an aspect of the present invention includes a piezoelectric film that converts a pressure input into a voltage; and first and second substrates with electrodes on which a plurality of electrodes for taking out the voltage are disposed.
A pressure-sensitive sensor that detects a voltage generated by the force received by the first electrode-attached substrate by sandwiching the piezoelectric film between the first and second electrode-attached substrates,
Between the electrodes disposed on the first electrode-attached substrate, a vibration absorber that absorbs vibrations generated by the pressure input received by the adjacent electrodes is disposed.
The vibration absorber disposed between the electrodes can suppress the vibration generated by the pressure input from propagating to the surroundings, and can reduce the voltage generated at a position other than the electrode corresponding to the input position.

It is preferable that the substrate with the first electrode and the piezoelectric film are fixed by the vibration absorber.
The first electrode-attached substrate and the piezoelectric film are fixed to each other by a vibration absorber, so that the gap between the first electrode-attached substrate and the piezoelectric film and the variation in the contact state can be reduced and generated by pressure input. Variation due to a change in the distance between the electrode and the piezoelectric film due to the vibration of the first electrode-attached substrate can be suppressed. In particular, this effect is effective for a porous piezoelectric film in which the piezoelectric film is greatly distorted when pressure is applied and the distance between the electrode and the piezoelectric film is easily changed. Since a voltage is also generated by a change in the distance between the electrode and the piezoelectric film, variation in the generated voltage based on a change in the distance between the electrode and the piezoelectric film can be suppressed by fixing the electrode-attached substrate and the piezoelectric film. Furthermore, by adhering the electrode-attached substrate and the piezoelectric film and suppressing the separation of the two, there is also an advantage that the propagation of vibrations in the substrate and the film surface can be suppressed as compared with the case where the substrate is not fixed.

It is preferable that a gap is provided between the vibration absorber and an electrode adjacent to the vibration absorber.
By providing a gap (air layer) between the vibration absorber and the electrode, the elastic wave is insulated at the boundary between the vibration absorber and the air layer. Propagation can be suppressed. Further, since the gap has a role as a clearance of the installation position of the vibration absorber, it is possible to prevent the generation of defective products that cover the electrodes even when the installation of the vibration absorber is deviated, and the yield is improved.

The vibration absorber is preferably composed of a pedestal and a vibration absorbing main body provided on the pedestal.
By providing the pedestal, it is possible to avoid installing the vibration absorber in a narrow concave portion between the electrodes, so that the width of the forming method is widened. In addition, the thickness of the vibration absorbing main body can be reduced to enable formation by printing or the like. That is, the versatility of the types of vibration absorbers that can be used and the method of forming the vibration absorbers is expanded.

The pedestal is preferably made of the same conductive material as that of the conductive material constituting the electrode.
By configuring the electrode and the pedestal with the same conductive material, the pedestal can also be formed at the time of electrode formation, and the manufacturing process can be simplified.

The vibration absorbing main body is preferably formed by screen printing.
By screen printing, it is possible to arrange the vibration absorber with high accuracy in a minute portion called the gap between the electrodes. In principle, screen printing is not good at printing in concave portions, but high-precision printing can be easily performed by providing a pedestal. The vibration-absorbing body desirably serves as an adhesive that fixes the electrode-attached substrate and the piezoelectric film, and screen printing allows printing of thick films compared to other general-purpose printing methods. Even if it exists, since the vibration-absorbing main body having a predetermined thickness can be formed, highly reliable adhesion becomes possible.

Each substrate constituting the first and second electrode-attached substrates is preferably a plastic film.
When the substrate is a plastic film, a flexible pressure sensitive sensor can be obtained.

The pressure sensor manufacturing method according to one aspect of the present invention includes a combination of a base and a vibration-absorbing body in a gap between the electrodes, wherein a piezoelectric film is sandwiched between substrates with electrodes in which a plurality of electrodes are arranged. A method of forming an electrode and a pedestal by removing a part of a conductive material laminated on a substrate; A step of printing an absorption body on the pedestal to form a vibration absorber; and a step of contacting the substrate on which the vibration absorber and the electrode are formed with a piezoelectric film.
Since the electrode and the pedestal can be manufactured in one process, the manufacturing can be simplified and the thickness of the vibration absorbing main body can be reduced, so that the vibration absorbing main body can be formed by printing.

[First Embodiment]
The pressure sensor 10 according to the first embodiment of the present invention will be described with reference to FIG.
3A is a cross-sectional view in the thickness direction of the pressure-sensitive sensor 10, and FIG. 3B is a view of the cross-section taken along PP ′ of the pressure-sensitive sensor 10 in FIG. 3A as viewed from the direction in which the electrodes are disposed. .

  The pressure-sensitive sensor 10 includes a first electrode-equipped substrate 14 in which electrodes 12, 12... Are arranged in a matrix on the substrate 13, and electrodes 12 ′, 12 ′, etc. on the substrate 13 ′. The second electrode-equipped substrate 14 ′ arranged in a matrix has a laminated structure in which the piezoelectric film 11 is sandwiched. A potential difference generated in the piezoelectric film is detected by the electrode pairs 12 and 12 'facing each other with the piezoelectric film 11 interposed therebetween.

  The substrates 14 and 14 ′ with electrodes sandwich the piezoelectric film 11 so that the electrodes 12 and 12 ′ on each substrate form an electrode pair, and paste the peripheral portions of the substrates 13 and 13 ′. The substrates with electrodes 14 and 14 'and the piezoelectric film 11 are laminated and fixed. Further, a vibration absorber 15 is provided between the electrodes 12 and 12 and between the electrodes 12 ′ and 12 ′ so as to have a gap 16.

  The piezoelectric film 11 is distorted when the vibration is transmitted to the piezoelectric film 11 when a pressure input is received. Due to the distortion generated in the piezoelectric film 11, the electrode pairs 12, opposed to each other with the piezoelectric film 11 interposed therebetween, A voltage corresponding to the magnitude of the strain received by the piezoelectric film 11 is generated between 12 '.

  The piezoelectric film 11 is not particularly limited, and a polyvinylidene fluoride (PVDF) film or a polylactic acid film, which is conventionally known as a piezoelectric film and exhibits piezoelectricity due to its molecular structure, electrostatic charge retention and deformability. It is possible to use a porous piezoelectric film such as a stretched porous polypropylene film that exhibits piezoelectricity due to the above, or a porous piezoelectric film such as a porous fluororesin film. Among these, a porous piezoelectric film is preferably used because of excellent piezoelectricity in the thickness direction. Since the porous piezoelectric film easily deforms and generates large distortion even with a small force, a highly sensitive sensor can be formed. A porous piezoelectric film has a large distortion at the time of pressure input, so the distance between the electrode and the piezoelectric film is likely to change. It affects the generated voltage. In this regard, in the present embodiment in which the electrode-attached substrate and the piezoelectric film are fixed, the variation in the electrode-piezoelectric film distance variation is suppressed, and as a result, the generated voltage varies based on the change in the electrode-piezoelectric film distance. Can be suppressed.

  As the porous piezoelectric film, a porous fluororesin film is preferably used from the viewpoint of heat resistance, chemical resistance, etc., and a porous polytetrafluoroethylene film is particularly preferably used.

  As the substrates 13 and 13 ′, an insulating substrate or a plastic film that can stably provide electrodes can be used. Preferably, it is a flexible plastic film that easily bends at an input point according to a pressure input. For example, plastic films such as polyester, polyethylene, and polyimide can be preferably used. A polyimide film is particularly preferable from the viewpoint of heat resistance and insulation.

  The electrodes 12 and 12 'are made of a conductive material, for example, a metal such as aluminum or copper, or a transparent conductive metal oxide such as ITO. The electrode pattern formed on the substrates 13 and 13 ′ may be formed by attaching a metal foil such as a copper foil or an aluminum foil to one surface of the substrate, and is proposed in Patent Document 2. Thus, it may be formed by punching.

  The vibration absorber 15 is provided with a gap 16 between the electrodes (between the electrodes 12, 12 or between the electrodes 12 ', 12') formed on the same substrate. In the mode of FIG. 3B, the vibration absorbers 15 provided between the electrodes 12 are continuous and are provided on the surface of the substrate 13 in a grid pattern. The vibration absorber 15 can absorb and attenuate the vibration of the substrate caused by the pressure input received by the substrate.

The thickness of the electrode is t, and the thickness of the vibration absorber 15 is preferably (t−3) μm or more, more preferably the electrode thickness t or more. This is because, when the pressure sensitive sensor 10 is assembled, when the substrate 13 and the piezoelectric film 11 are stacked by pressing, the vibration absorber is strongly pressed against the piezoelectric film, so that the vibration absorbing body is easily fixed to the piezoelectric film.
The thickness of the vibration absorber 15 is preferably (t + 40) μm or less. This is because if the vibration absorber 15 becomes too thick, the variation in the distance between the electrode and the piezoelectric film is increased based on the vibration absorber 15.

  The vibration absorber 15 may be any material as long as it can absorb vibrations. For example, vibration absorbing materials such as rubber and gel, adhesive materials such as pressure-sensitive adhesives, and adhesives can be used. Of these, an adhesive substance such as an adhesive film or a liquid adhesive is preferably used. It is because it has the advantage that the fixed state of the board | substrate with an electrode and a piezoelectric film can be stabilized. The adhesive film is preferable because the vibration absorber can be formed with high positional accuracy and thickness accuracy at low cost by laminating an adhesive film in which electrode portions are hollowed out by pressing, etching, or the like on the substrates 14 and 14 'with electrodes. The liquid adhesive is preferable because it can be applied and printed on a desired site.

  The adhesive and adhesive film used as the vibration absorber 15 desirably include a thermoplastic resin that provides good adhesiveness and flexibility and a thermosetting resin that imparts heat resistance. Thermoplastic resins include acrylic resin, polyamide resin, polystyrene resin, polyester resin, polycarbonate resin, polyphenylene oxide resin, polyphenylene sulfide resin, polysulfone resin, polyetherimide resin, polyetheretherketone resin, polyacetal resin, and ketone resin. Although mentioned, an acrylic resin, a polyamide resin, and a polyester resin are preferable from a softness | flexibility, adhesiveness with a base material, and a heat resistant viewpoint. As the thermosetting component, an epoxy resin, a phenol resin, a urethane resin, a melamine resin, an unsaturated polyester resin, a cross-linked silicone, and the like are particularly preferable. Among them, an epoxy resin is preferable from the viewpoint of heat resistance and adhesiveness.

  The first electrode-equipped substrate 14 and the second electrode-equipped substrate 14 ′ have the same configuration and the vibration absorber 15 is disposed in the same manner. Description is omitted.

  The structure in which the substrate with electrodes and the piezoelectric film can be fixed by the vibration absorber suppresses the deformation of the substrate as shown in FIG. 2B, which can be caused by the pressure input, as compared with the pressure-sensitive sensor in which only the peripheral portion is fixed. Can do. That is, even when the substrate film vibrates according to the pressure input, it is possible to prevent an increase in amplitude and to suppress variations in the relative position between the electrode and the piezoelectric film.

The method of disposing the vibration absorber 15 on the substrates 13 and 13 ′ can be appropriately selected according to the type of the vibration absorber 15, the form of the vibration absorber 15, and the distance between the electrodes. For example, when the vibration absorber is made of a liquid adhesive, it can be disposed on the substrates 13 and 13 ′ by coating, printing, etching, or the like.
When the distance between the electrodes disposed on the same substrate is 2 mm or less, it is preferable to form the vibration absorber by printing. This is because an adhesive film having a film width of 2 mm or less is insufficient in rigidity and tends to be deformed, so that it is difficult to laminate with high positional accuracy.
If the distance between the electrodes on the same substrate is 0.2 mm or less, an adhesive film is laminated on the entire surface, or a liquid adhesive substance is applied to the entire surface and dried, and then a necessary portion is formed by laminating the photosensitive material and exposing and developing. It is preferable to form the vibration absorber by the method of leaving If it is the said method, an arrangement | positioning position can be adjusted with high precision.

  Moreover, when using an adhesive agent and an adhesive film as the vibration absorber 15, it is desirable to laminate | stack with a piezoelectric film in a semi-hardened state, and to harden | cure after lamination | stacking. In the semi-cured state, it has high flexibility and deformability, so it can spread out to fill the surface irregularities of the piezoelectric film and substrate, and after complete curing, it has high heat resistance and other reliable and strong adhesive strength. This is because it can be realized.

  In the pressure-sensitive sensor 10 according to the first embodiment having the above-described configuration, the piezoelectric film 11 is deformed by the pressure input in the direction of the white arrow shown in FIG. 3A, and accordingly, the input position is closest to the input position. The largest voltage is generated between the electrode pairs 12 and 12 '. By detecting such a voltage, the magnitude and input position of the pressure input can be detected. On the other hand, the vibration accompanying the pressure input also propagates around the pressure input position. However, in the pressure-sensitive sensor 10 of the present embodiment, the vibration absorber 15 has a function of attenuating the generated vibration, and the air layer and the electrode 12 are provided by providing a gap 16 between the vibration absorber and the electrode. Since the vibration is also attenuated at the boundary portion between the air layer and the vibration absorber 15, the deformation of the piezoelectric film 11 at a position away from the input position can be prevented. Furthermore, when the piezoelectric film 11 and the electrode-attached substrate 14 are fixed with an adhesive constituting the vibration absorber 15, vibration of the electrode-provided substrate 14 itself generated by pressure input can be prevented. This means that a voltage generated based on the piezoelectric constant of the piezoelectric film 11 is obtained at the input position, and the voltage generated at the peripheral electrode pair can be suppressed. Therefore, in the pressure-sensitive sensor 10 having the above-described configuration, the voltage signal detected with respect to the pressure input position and the size is limited to a narrow range, so that the resolution is improved.

  Moreover, in the pressure-sensitive sensor 10 of this embodiment, since the electrode 12 and the piezoelectric film 11 are not joined by the adhesive agent etc., it is advantageous at the point that there is no absorption loss of the pressurization energy by an adhesive agent. Furthermore, since the relative position and contact state between the electrode 12 and the piezoelectric film 11 change from the time of pressurization input, that is, from the time of pressurization load to the time of release, an instantaneous pulse voltage is generated at the pressure input position, and the load There is an advantage that the pressure input position to be detected can be detected sharply. In particular, when the piezoelectric film 11 and the electrode-equipped substrate 14 are fixed with the adhesive constituting the vibration absorber 15, the vibration generated at the time of applying and releasing the pressure can be attenuated early by suppressing the generation of the standing wave. Therefore, the voltage generated by the pressure input can be obtained as a sharp pulse wave.

  In the pressure sensor 10 of the form shown in FIG. 3, the vibration absorber 15 is continuously provided between the electrodes, but the pressure sensor of the present invention is not limited to this. For example, as in the pressure-sensitive sensor 10 ′ shown in FIG. 4, individual vibration absorbers 15 ′ may be interspersed independently between the electrodes 12, 12 or 12 ′, 12 ′.

  Further, in the pressure sensor 10, the shape of each electrode 12 is a square, but the shape is not limited to this, and can be selected as appropriate, such as a circle or a polygon. Moreover, although the electrode 12 is provided in matrix form, an electrode pattern can be designed arbitrarily. It is only necessary that the electrode pair is formed so that the voltage to be detected can be taken out efficiently. For example, strip-like electrodes may be arranged on the substrate in a striped manner with a predetermined interval. In this case, the crossing positions form a pair of electrodes by combining the band-shaped electrodes so as to cross each other with the piezoelectric film interposed therebetween.

The joint portion 19 is a joint portion between the substrates 14 and 14 ′ with electrodes, and is usually provided along the periphery of the substrates 13 and 13 ′. The bonding method is not particularly limited, and screwing, bonding with an adhesive, bonding by heating or pressing, and the like can be used.
In the case where the vibration absorber is made of an adhesive, the substrate and the piezoelectric film are fixed by the vibration absorber, so that the bonding between the piezoelectric film and the substrate film with electrodes at the peripheral portion is not essential.

[Second Embodiment]
A pressure sensor according to a second embodiment of the present invention will be described with reference to FIGS. In the pressure-sensitive sensor 20 of the second embodiment, a combination of a pedestal and a vibration absorbing main body is used as the vibration absorber, and a part of the electrode also serves as the pedestal.

  FIG. 5 is a sectional view of the pressure sensor 20 cut in the thickness direction. 6A is a plan view of the first electrode-equipped substrate 24 used in the pressure-sensitive sensor 20, and FIG. 6B is a plan view of the second electrode-equipped substrate 24 ′ used in the pressure-sensitive sensor 20. . The pressure-sensitive sensor 20 sandwiches the piezoelectric film 21 between the first electrode-equipped substrate 24 shown in FIG. 6A and the second electrode-equipped substrate 24 ′ shown in FIG. 6B having the same configuration. In the cross-sectional view of FIG. 5, each of the electrode-attached substrates 24 and 24 ′ represents the XX ′ cut surface of FIG. 6A and the YY ′ cut surface of FIG. 6B.

  The first (or second) electrode-equipped substrate 24 (or 24 ′) is obtained by arranging strip-shaped electrodes 22 (22 ′) on the substrate 23 in parallel at a predetermined interval. A vibration absorber 25 comprising a combination of a pedestal 27 (27 ′) and a vibration absorbing main body 28a (28a ′) provided on the pedestal 27 (27 ′) between the electrodes 22 and 22 (between 22 ′ and 22 ′). , 25... (25 ′, 25 ′...) Are juxtaposed in parallel with the strip electrode 22 (22 ′) at a predetermined interval. Further, on the belt-like electrode 22 (22 ′), the vibration absorbing body 28b (28b ′) is disposed between the electrodes 22 (between 22 ′) at positions corresponding to every other vibration absorber 25 (25 ′). Are provided so as to be substantially parallel to the row of the vibration absorbers 25 (25 ′) disposed in the cylinder.

  The first electrode-attached substrate 24 and the second electrode-provided substrate 24 ′ sandwich the piezoelectric film 21 so that the respective strip-like electrodes 22 and 22 ′ are opposed to each other. A portion where the belt-like electrode 22 and the belt-like electrode 22 ′ intersect with each other across the piezoelectric film 21 forms a pair of electrodes for extracting a detected voltage. That is, in the strip-shaped electrode 22 (22 '), the portion 22a (22a') where the vibration absorbing main body 28b is not provided functions as an electrode for taking out the detected voltage. On the other hand, in the strip electrode 22 (22 '), the portion where the vibration absorbing main body 28b is provided functions as a pedestal.

  The constituent material of the pedestals 27 and 27 'is not particularly limited, but is preferably made of the same material as the electrodes 22 and 22'. By configuring the pedestal with the same conductive material as the electrode, the pedestal and the electrode can be formed in the same process. For example, since the pedestal and the electrode pattern can be simultaneously formed by etching or punching from the metal foil laminated on the substrate, an additional process for forming the pedestal is not required in the manufacturing process of the pressure sensitive sensor.

The vibration absorbing main bodies 28a, 28b, 28a ′, 28b ′ can all be made of the material exemplified as the vibration absorber in the first embodiment. That is, a vibration absorbing material, an adhesive material, or the like can be used, and among these, an adhesive or an adhesive film is particularly preferably used.
When the vibration absorbing main body is made of an adhesive, the vibration absorbing main body can be disposed on the pedestal by applying or printing the adhesive. In this case, the thickness of the adhesive is preferably 2 μm to 100 μm, more preferably 5 μm to 50 μm, and still more preferably 7 μm to 30 μm. If the thickness is too thin, a strong adhesive force cannot be obtained, and the adhesive reliability against environmental loads such as repetitive stress, vibration load, and heat cycle is lowered. On the other hand, if the thickness is too large, the thickness varies and bleeding tends to occur, and accurate printing becomes difficult.

  As a printing method, a printing method capable of printing a thick film of 2 μm or more can be used. Specifically, screen printing, intaglio printing, and ink jet printing can be adopted, and among them, printing accuracy is good, low cost, and 5 μm. Screen printing capable of the above thick film printing is preferable. Since the vibration absorbing main bodies 28a and 28a 'are formed on the pedestals 27 and 27', respectively, and the vibration absorbing main bodies 28b and 28b 'are respectively formed on the strip electrodes 22 and 22', the thickness can be reduced appropriately. Therefore, by using a vibration absorber composed of a combination of a pedestal and a vibration absorbing main body, it is possible to reduce variations in thickness when formed by printing such as screen printing, and to improve the uniformity of the distance between the piezoelectric film and the electrode.

  The vibration absorbing main body 28a (28a ′) provided on the pedestal 27 (27 ′) is preferably smaller than the mounting area so as not to protrude from the mounting surface of the pedestal 27 (27 ′). It is preferable to provide it.

  In the pressure-sensitive sensor 20, the first electrode-provided substrate 24 and the second electrode-provided substrate 24 'are bonded and fixed by a bonding portion 29 provided along the peripheral edges of the substrates 23 and 23'. As a bonding method in the bonding portion 29, screwing, bonding with an adhesive, bonding by heating or pressurization, or the like can be employed. The laminated structure of the first electrode-attached substrate 24, the piezoelectric film 21, and the second electrode-provided substrate 24 ′ is composed of the piezoelectric film 21 by vibration absorbing main bodies 28a, 28b (28a ′, 28b ′) made of an adhesive. And the electrode-attached substrates 24 and 24 ′ are bonded and fixed, so that the joining by the joining portion 29 is not necessary.

  In the pressure-sensitive sensor 20, the first electrode-equipped substrate 24 and the second electrode-equipped substrate 24 ′ used the electrode-equipped substrate, but electrodes having different electrode patterns and vibration absorber configurations are used. A combination of attached substrates may be used. For example, the electrode pattern formed on one substrate with electrodes may be in a matrix form, and the electrode pattern formed on the other substrate with electrodes may be formed by arranging strip-like electrodes in a stripe form. Further, for example, the electrode pattern formed on one substrate with electrodes may be in the form of a matrix, and the electrode pattern formed on the other substrate with electrodes may have only one large electrode. Further, with respect to the vibration absorber, the vibration absorber provided on one substrate may be a combination of a pedestal and a vibration absorption body, and the vibration absorber provided on the other substrate may be the vibration absorber illustrated in the first embodiment. .

  In the pressure sensor 20, the pedestal 27 (27 ') has a square shape, but the shape is not limited to this, and a circular shape, a polygonal shape, or the like can be selected as appropriate.

  Moreover, in the aspect which uses a part of strip | belt-shaped electrode as a base, in the pressure-sensitive sensor 20, the vibration absorption main body 28b (28b ') provided on a strip | belt-shaped electrode is the vibration absorber 25 (25'25) arrange | positioned between strip | belt-shaped electrodes. ) Except for the crossing part of the two strip electrodes that sandwich the piezoelectric film (the part that forms the electrode pair for extracting the detected voltage). A vibration absorbing main body may be provided in the range, and can be selected as appropriate depending on the size and arrangement of the vibration absorbers disposed between the strip electrodes.

[Method of manufacturing pressure-sensitive sensor]
As the vibration absorber, a combination of a pedestal and a vibration absorbing main body is used, and as the pedestal, a pressure sensitive sensor composed of the same conductive material as the conductive material constituting the electrode is preferably manufactured by the following manufacturing method. can do.

That is, the step of forming the electrode and the pedestal by removing a part of the conductive material laminated on the substrate;
Printing the vibration absorbing body on the pedestal to form the vibration absorber; and contacting the piezoelectric film with the substrate on which the vibration absorber and the electrode are formed.

A method for stacking the substrate and the conductive material is not particularly limited, but the conductive material may be deposited on the substrate, or a copper foil, an aluminum foil, or the like may be attached. A method for removing a part of the conductive material stacked on the substrate is not particularly limited, and can be performed by etching, punching, or the like.
The electrode pattern and pedestal to be formed may be a matrix electrode as shown in the first embodiment and a pedestal formed continuously in the gap between the electrodes, or electrodes arranged in a matrix You may form so that a base may be scattered in the gap | interval between electrodes. Further, as shown in the second embodiment, it may be formed in such a manner that pedestals are interspersed with belt-like electrodes and gaps between electrodes. Moreover, a part of electrode may serve as a base like 2nd Embodiment.

  Examples of the method for printing the vibration absorbing main body on the pedestal include screen printing and ink jet printing, and screen printing is preferable. When the vibration absorbing main body is formed by printing, a printing pattern in which the vibration absorbing main body is scattered is preferable. This is because a continuous wide and wide print pattern tends to cause a difference in thickness between the print edge and the center.

  The piezoelectric film is sandwiched between the substrate with electrodes on which the vibration absorber is formed as described above. Since the piezoelectric film is adhered and fixed by a vibration absorbing main body composed of an adhesive, the bonding step between the piezoelectric film and the substrate film with electrodes at the peripheral portion is not essential.

  The best mode for carrying out the present invention will be described with reference to examples and comparative examples. The examples and comparative examples do not limit the scope of the invention.

〔Example〕
A CCL (Copper Clad Laminate) copper foil obtained by laminating a 18 μm thick copper foil on a 25 μm thick polyimide resin is etched, and as shown in FIG. d) While being arranged in a matrix of 2 mm, a square pedestal 37a with one side (l _a ) of 1 mm, a square pedestal 37b with one side (l _b ) of 1.5 mm, and thin wires and external terminals (not shown) were formed. At this time, the electrode 32 is electrically connected to the external terminal through a fine wiring. Further, an adhesive was printed on the pedestals 37a and 37b by screen printing to form vibration-absorbing main bodies 38a (Φ _a = 0.8 mm) and 38b (Φ _b = 1.2 mm) having a thickness of 15 μm. The vibration absorber 35a includes a pedestal 37a and a vibration absorption body 38a, and the vibration absorption body 35b includes a pedestal 37b and a vibration absorption body 38b.

The composition of the adhesive used as the vibration absorbing main body is as follows.
Acrylic resin (manufactured by Shin-Nakamura Kogyo "Vanaresin GH-7190"): 100 parts by mass,
Epoxy resin (DIC Corporation “EPICLON-N740”): 34.0 parts by mass,
Silica fine powder (Nippon Aerosil "AEROSILRX300"): 3.8 parts by mass,
Antifoaming agent (BIC Chemie Japan "BYK-54"): 2.0 parts by mass,
Acid anhydride (Nippon Rika Co., Ltd. “Licacid MH-700”): 30.1 parts by mass,
Imidazole (Shikoku Chemicals “2E4MZ”): 3.8 parts by mass,
Diethylene glycol monomethyl ether acetate: 140 parts by mass.

A porous polytetrafluoroethylene piezoelectric film (thickness: 24 μm, piezoelectric constant d ₃₃ : 100 pC / N) is sandwiched between the two substrates with electrodes produced in this manner so that the electrodes on the substrate face each other. In this state, a pressure sensor was fabricated by laminating by hot pressing (1.4 MPa, 130 ° C. for 15 minutes). In the manufactured pressure-sensitive sensor, a range in which the number of electrodes was 4 × 4 was selected, and 7 of them were named electrodes A to G as shown in FIG.

[Comparative example]
A pressure-sensitive sensor was produced in the same manner as in the example except that the vibration absorber was not formed.

[Relationship between electrode position and generated voltage]
Using the pressure-sensitive sensors of Examples and Comparative Examples prepared above as measurement samples, the external terminals wired to the electrode pairs formed on both sides of the piezoelectric film were electrically connected, and as shown in FIG. A 0.3 g iron ball was freely dropped from the height of 20 cm toward the electrode D. The voltage generated by the drop was measured at each electrode position A to G. A graph showing the relationship between the electrode position and the generated voltage in each measurement sample is shown in FIG. Note that the “maximum value-minimum value” of the voltage generated by dropping the iron ball was taken as the measured value, the measurement by dropping the iron ball was performed five times, and the average value was taken as the voltage generated by the electrode. In FIG. 10, the result of the example sample is indicated by a solid line, and the result of the comparative example sample is indicated by a broken line.

  From FIG. 10, the voltage generated at the electrode position D corresponding to the dropping point of the iron ball was almost the same in the example and the comparative example. However, the voltages generated at the electrode positions A, B, C, E, and F other than the dropping point were all lower in the example. In particular, in the example, there was almost no difference between the generated voltages of the adjacent (C, E) and the peripheral positions (A, B, F, G), and the voltage was generated specifically at the falling point. On the other hand, in the comparative example, a voltage corresponding to 1/2 or more of the falling point was generated in the adjacent (C, E) or the peripheral position (B, F). From these results, it is considered that in the example, the vibration absorber was able to absorb the vibration accompanying the pressure input received at the dropping point and to suppress the distortion of the piezoelectric film in the vicinity and the periphery.

[Measurement of voltage signal waveform]
As shown in FIG. 9, the measurement samples of the example and the comparative example were set, and the waveform of the generated voltage when the iron ball was freely dropped at each of the electrode positions A, D, and F was measured with an oscilloscope. The results are shown in FIG.

  From FIG. 11, in the Example, the pulse waveform which shows that the voltage was instantaneously generated at the time of dropping was obtained in any of the electrode positions A, D and F. On the other hand, in all of the comparative examples, the rise of the voltage generated from the time of dropping and the change of the fall until the reverse voltage was generated were gradual, and the generated voltage was different depending on the electrode position. In the comparative example, since the piezoelectric film and the substrate are not fixed at the electrode positions, the rise time and the fall time become longer because the substrate is deformed in a wide range including the periphery of the position where the pressure input is received and the substrate vibrates. It is thought. Also, it is assumed that the variation in the generated voltage difference is due to the variation in the substantial spatial distance between the electrode and the piezoelectric film.

  According to the present invention, as a pressure-sensitive sensor, it is possible to increase the resolution of the pressure input position, the detection sensitivity of the input size, the time resolution, and the like, so that it can be suitably used for sensors, touch pads, touch panels, and the like.

10, 10 ', 20 Pressure sensor 1, 11, 21 Piezoelectric film 2, 12, 12', 32 Electrode 3 Substrate 13, 23 First substrate 13 ', 23' Second substrate 4 Adhesives 14, 24 First Substrate with electrodes 14 ', 24' Substrate with electrodes 15, 15 ', 25, 25', 35a, 35b Vibration absorbers 16, 16 ', 26 Gap 22, 22' Strip electrodes 27, 27 ', 37a, 37b Pedestals 28a, 28b, 28a ′, 28b ′, 38a, 38b Vibration absorbing main bodies 19, 29

Claims (8)

A piezoelectric film that converts a pressure input into a voltage; and a substrate with first and second electrodes on which a plurality of electrodes for taking out the voltage are arranged,
A pressure-sensitive sensor that detects a voltage generated by the force received by the first electrode-attached substrate by sandwiching the piezoelectric film between the first and second electrode-attached substrates,
Between the electrodes disposed on the substrate with the first electrode, a vibration absorber that absorbs vibrations generated by the pressure input received by the adjacent electrode is disposed ,
A pressure-sensitive sensor in which a gap is provided between the vibration absorber and an electrode adjacent to the vibration absorber.   A piezoelectric film that converts a pressurized input into a voltage; and
  A first and second electrode-attached substrate in which a plurality of electrodes for taking out the voltage are arranged;
  A pressure-sensitive sensor that detects a voltage generated by the force received by the first electrode-attached substrate by sandwiching the piezoelectric film between the first and second electrode-attached substrates,
  Between the electrodes disposed on the substrate with the first electrode, a vibration absorber that absorbs vibrations generated by the pressure input received by the adjacent electrode is disposed,
  The vibration absorber is a pressure-sensitive sensor including a pedestal and a vibration absorbing main body provided on the pedestal. The pressure-sensitive sensor according to claim 1, wherein the vibration absorber is composed of a pedestal and a vibration absorption main body provided on the pedestal. The pressure sensor according to claim 2 , wherein the pedestal is made of the same conductive material as that of the conductive material constituting the electrode. The pressure-sensitive sensor according to any one of claims 1 to 4 , wherein the first electrode-attached substrate and the piezoelectric film are fixed by the vibration absorber. The pressure-sensitive sensor according to any one of claims 2 to 4, wherein the vibration absorbing main body is formed by screen printing.   The pressure-sensitive sensor according to any one of claims 1 to 6, wherein each of the substrates constituting the first and second electrode-attached substrates is a plastic film. Forming electrodes and pedestals by removing a portion of the conductive material laminated on the substrate;
A method of manufacturing a pressure-sensitive sensor, comprising: forming a vibration absorber by printing a vibration absorption body on the pedestal; and contacting the substrate on which the vibration absorber and the electrode are formed with a piezoelectric film.