Sensor module

Abstract

The sensor module includes: an elastic member including a resin; a first sensor in contact with the elastic member and including an upper electrode, a piezoelectric film, and a lower electrode; and a switch in which the first sensor outputs a first signal corresponding to a deformation of the elastic member, the switch having a function of short-circuiting the upper electrode and the lower electrode, the lower electrode being a signal electrode.

Description

Technical Field

[0001] The present invention relates to a sensor module including a sensor for detecting deformation of a member. Background Art

[0002] Patent document 1 describes a grip load detection device for detecting a load applied by a user. The grip load detection device includes a housing and a sensor. The housing is gripped by a user. The sensor is attached to the housing. The sensor detects a load applied to the housing due to the grip of the user. Specifically, the sensor includes a piezoelectric film, a first electrode, and a second electrode. The sensor outputs a signal based on a potential difference between the first electrode and the second electrode.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2020 / 153075 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] In the field of the grip load detection device described in Patent Document 1, a sensor module in which a sensor for detecting deformation of a member is unlikely to malfunction is desired.

[0008] An object of the present invention is to provide a sensor module in which a sensor for detecting deformation of a member is less likely to malfunction.

[0009] Solutions for solving problems

[0010] The inventors of the present application have considered the situation that a sensor including a piezoelectric film, a signal electrode, and a reference electrode for detecting deformation of a member malfunctions. The sensor outputs a signal based on a potential difference between the signal electrode and the reference electrode.

[0011] As a result of the investigation, the inventor of the present application noticed that, in the case where the component to which the sensor is attached contains a resin that is easily charged, when the sensor is attached to the component in such a way that the signal electrode is close to the component, the sensor may malfunction. For example, the component may be positively charged due to friction between the components. The signal electrode may be negatively charged due to the influence of the charged component. In this case, the potential difference between the signal electrode and the reference electrode changes. As a result, the inventor of the present application noticed that even if the component is not deformed, the sensor may output a signal indicating that the component is deformed.

[0012] Based on the above considerations, the inventors of the present application have studied a sensor module in which a sensor is less likely to malfunction. As a result, the inventors of the present application have come up with the following invention.

[0013] A sensor module according to one embodiment of the present invention includes:

[0014] an elastic member comprising a resin;

[0015] a first sensor that contacts the elastic member and includes an upper electrode, a piezoelectric film, and a lower electrode; and

[0016] switch,

[0017] wherein the first sensor outputs a first signal corresponding to the deformation of the elastic member,

[0018] The switch has a function of short-circuiting the upper electrode and the lower electrode.

[0019] The lower electrode is a signal electrode.

[0020] In the following, X and Y are components or members of the sensor module. In this specification, unless otherwise specified, the parts of X are defined as follows. The front part of X refers to the front half of X. The rear part of X refers to the rear half of X. The left part of X refers to the left half of X. The right part of X refers to the right half of X. The upper part of X refers to the upper half of X. The lower part of X refers to the lower half of X. The front end of X refers to the front end of X. The rear end of X refers to the rear end of X. The left end of X refers to the left end of X. The right end of X refers to the right end of X. The upper end of X refers to the upper end of X. The lower end of X refers to the lower end of X. The front end of X refers to the front end of X and its vicinity. The rear end of X refers to the rear end of X and its vicinity. The left end of X refers to the left end of X and its vicinity. The right end of X refers to the right end of X and its vicinity. The upper end of X refers to the upper end of X and its vicinity. The lower end of X refers to the lower end of X and its vicinity.

[0021] In addition, "X is located above Y." means that X is located directly above Y. Therefore, when viewed in the up-down direction, X overlaps with Y. "X is located above Y." means that X is located directly above Y and X is located obliquely above Y. Therefore, when viewed in the up-down direction, X may overlap with Y or may not overlap with Y. This definition also applies to directions other than the up direction.

[0022] Effects of the Invention

[0023] According to the sensor module according to one embodiment of the present invention, a sensor for detecting deformation of a member is less likely to malfunction. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a perspective view showing the appearance of the sensor module 1 .

[0025] Figure 2 1 is a diagram showing an example of connection among the first sensor 11 , the switch 12 , and the calculation circuit 13 .

[0026] Figure 3 This is a diagram showing the first sensor 11 viewed downward.

[0027] Figure 4 yes Figure 3 AA cross-section diagram in.

[0028] Figure 5 It is a diagram showing an example of deformation of the piezoelectric film 111 .

[0029] Figure 6 1 is a diagram showing an example of the first signal Sig1 generated due to the elastic member 10 being charged.

[0030] Figure 7 : is a diagram showing an example of the first signal Sig1 generated when the elastic member 10 is deformed so as to be twisted around the central axis CAX.

[0031] Figure 8 2 is a flowchart showing an example of the process P executed by the calculation circuit 13 .

[0032] Fig. 9 1 is a diagram showing the waveform of the first signal Sig1 when the arithmetic circuit 13 executes the process P.

[0033] Fig.10 It is a perspective view showing the appearance of a sensor module 1 a according to Modification 1.

[0034] Fig.11 1 is a diagram showing an example of connection among the switch 12 , the calculation circuit 13 , and the second sensor 14 a .

[0035] Fig.12 : is a figure which shows the 2nd sensor 14a.

[0036] Fig.13 This is a diagram showing an example of processing by the calculation circuit 13b included in the sensor module 1b according to the second modification.

[0037] Fig.14 This is a block diagram showing an example of a sensor module 1 c according to Modification 3.

[0038] Fig.15 This is a block diagram showing an example of a sensor module 1 d according to Modification 4. DETAILED DESCRIPTION

[0039] [First embodiment]

[0040] Hereinafter, a sensor module 1 according to a first embodiment of the present invention will be described with reference to the drawings. Figure 1 It is a perspective view showing the appearance of the sensor module 1 . Figure 2 1 is a diagram showing an example of connection among the first sensor 11 , the switch 12 , and the calculation circuit 13 . Figure 3 This is a diagram showing the first sensor 11 viewed downward. Figure 4 yes Figure 3 AA cross section in. Figure 4 In the figure, description of the lower end portion, the left end portion, and the right end portion of the elastic member 10 is omitted. Figure 5 It is a diagram showing an example of deformation of the piezoelectric film 111 .

[0041] In this embodiment, directions are defined as follows. Figure 1 As shown, the direction in which the sensor module 1 extends is defined as the left-right direction. The direction in which the elastic member 10 and the first sensor 11 are arranged is defined as the up-down direction. The direction in which the elastic member 10 and the first sensor 11 are arranged in this order is defined as the upper direction. The direction in which the first sensor 11 and the elastic member 10 are arranged in this order is defined as the lower direction. The direction orthogonal to the left-right direction and the up-down direction is defined as the front-back direction. However, the left-right direction, the up-down direction, and the front-back direction are directions defined for the purpose of explanation. Therefore, the left-right direction, the up-down direction, and the front-back direction of the sensor module 1 in actual use may not necessarily be consistent with the front-back direction, the up-down direction, and the left-right direction in this embodiment.

[0042] The sensor module 1 is used, for example, in a training device. Figure 1 and Figure 2 As shown, the sensor module 1 includes an elastic member 10 , a first sensor 11 , a switch 12 , and a calculation circuit 13 .

[0043] The elastic member 10 includes a resin. For example, the elastic member 10 includes an acrylic resin. Figure 1 As shown, the elastic member 10 is in the shape of a rod. Specifically, the elastic member 10 is in the shape of a rod having a central axis CAX extending in the left-right direction. The elastic member 10 has elasticity. The elastic member 10 is deformed around the central axis CAX. Specifically, the user holds the left and right parts of the elastic member 10. For example, when looking in the right direction, the user twists the left part of the elastic member 10 clockwise around the central axis CAX. As a result, as shown in FIG. Figure 1 As shown in FIG. 1 , a circumferential force F1 is applied to the left portion of the elastic member 10. In addition, when viewed in the right direction, the user twists the right portion of the elastic member 10 counterclockwise about the central axis CAX. Figure 1 As shown, a circumferential force F2 is applied to the right portion of the elastic member 10. As a result, the elastic member 10 is deformed in a twisted manner about the central axis CAX.

[0044] like Figure 3 As shown, the first sensor 11 is in a rectangular shape having a long side extending in the left-right direction and a short side extending in the front-back direction. Figure 2 As shown, the first sensor 11 includes a piezoelectric film 111 , an upper electrode 110 , a lower electrode 112 and a detection circuit 113 .

[0045] like Figure 3 and Figure 4 As shown, the piezoelectric film 111 is in a sheet shape having long sides extending in the left-right direction and short sides extending in the front-back direction. The piezoelectric film 111 has an upper main surface SF1 and a lower main surface SF2 arranged in the up-down direction. The upper main surface SF1 and the lower main surface SF2 are arranged in the downward direction.

[0046] The piezoelectric film 111 generates an electric charge corresponding to the amount of deformation of the piezoelectric film 111. The piezoelectric film 111 has the following characteristics: the polarity of the electric charge generated when the piezoelectric film 111 is stretched in the right rear direction or the left front direction is opposite to the polarity of the electric charge generated when the piezoelectric film 111 is stretched in the right front direction or the left rear direction. Specifically, the piezoelectric film 111 is a film formed of a chiral polymer. An example of a chiral polymer is polylactic acid (PLA), and in particular, left-handed polylactic acid (PLLA). The main chain of PLLA has a helical structure. PLLA has piezoelectricity when the molecules are oriented by uniaxial stretching. Therefore, the piezoelectric film 111 has piezoelectricity. The piezoelectric film 111 has a piezoelectric constant of d14. As Figure 3 and Figure 5 As shown, the uniaxial stretching direction OD of the piezoelectric film 111 forms an angle of 0 or 180 degrees relative to the left and right directions. The 0 degree includes, for example, an angle of about 0 degrees ± 10 degrees. Similarly, the 180 degrees includes, for example, an angle of about 180 degrees ± 10 degrees. Thus, the piezoelectric film 111 generates an electric charge when the piezoelectric film 111 is stretched in the right rear direction, the left front direction, the right front direction, or the left rear direction. For example, the piezoelectric film 111 generates a positive charge when it is stretched in the right rear direction or the left front direction. For example, the piezoelectric film 111 generates a negative charge when it is stretched in the right front direction or the left rear direction. The size of the charge depends on the amount of deformation of the piezoelectric film 111 caused by stretching or compression.

[0047] The upper electrode 110 is a reference electrode connected to a reference potential VE. As an example, the upper electrode 110 is connected to a ground potential. The upper electrode 110 is fixed to the upper main surface SF1 by an adhesive (not shown) such as OCA (Optically Clear Adhesive). Therefore, the upper electrode 110 is located on the piezoelectric film 111. The upper electrode 110 covers the upper main surface SF1. The upper electrode 110 includes, for example, a PET film and an ITO layer. The ITO layer of the upper electrode 110 is in contact with the lower surface of the PET film of the upper electrode 110. The ITO layer of the upper electrode 110 covers the lower surface of the PET film of the upper electrode 110.

[0048] The lower electrode 112 is a signal electrode. The lower electrode 112 is fixed to the lower main surface SF2 by an adhesive such as OCA (not shown). Therefore, the lower electrode 112 is located below the piezoelectric film 111. The lower electrode 112 covers the lower main surface SF2. The lower electrode 112 includes, for example, a PET film and an ITO layer. The ITO layer of the lower electrode 112 is in contact with the upper surface of the PET film of the lower electrode 112. The ITO layer of the upper electrode 110 covers the upper surface of the PET film of the upper electrode 110. Figure 1 and Figure 4 As shown, the lower electrode 112 is in contact with the elastic member 10. The elastic member 10 is located below the lower electrode 112.

[0049] like Figure 2 As shown, the detection circuit 113 is electrically connected to the upper electrode 110 and the lower electrode 112. The detection circuit 113 includes a voltage follower (not shown), an AD converter (not shown), etc. The voltage follower converts the charge generated by the piezoelectric film 111 into a voltage signal. The AD converter generates a digital signal by performing AD conversion on the voltage signal.

[0050] The first sensor 11 outputs a first signal Sig1 based on a potential difference between the upper electrode 110 and the lower electrode 112. The first sensor 11 outputs the first signal Sig1 corresponding to the deformation of the elastic member 10. Figure 1 As shown, the first sensor 11 is in contact with the elastic member 10. The first sensor 11 is in contact with the outer peripheral surface of the elastic member 10. The lower electrode 112 of the first sensor 11 is fixed to the outer peripheral surface of the elastic member 10 by an adhesive such as OCA (not shown). As a result, the first sensor 11 is deformed as the elastic member 10 is deformed. The first sensor 11 outputs a first signal Sig1 corresponding to the deformation of the first sensor 11.

[0051] In this embodiment, the first sensor 11 detects the deformation of the elastic member 10 around the central axis CAX. For example, when viewed in the right direction, the user twists the left portion of the elastic member 10 clockwise around the central axis CAX. Figure 5As shown in FIG. 1 , the piezoelectric film 111 is stretched in the left-front direction. In addition, when viewed in the right direction, the user twists the right part of the elastic member 10 counterclockwise around the central axis CAX. Figure 5 As shown, the piezoelectric film 111 is stretched in the right rear direction. Therefore, positive charges are generated in the piezoelectric film 111. As a result, the first sensor 11 outputs the first signal Sig1 having a positive polarity with respect to the reference potential VE.

[0052] The switch 12 has a function of short-circuiting the upper electrode 110 and the lower electrode 112. Specifically, the switch 12 is connected in parallel with the upper electrode 110 and the lower electrode 112. When the switch 12 is turned on, the upper electrode 110 is electrically connected to the lower electrode 112 via the switch 12. In other words, the switch 12 short-circuits the upper electrode 110 and the lower electrode 112. The switch 12 is, for example, a switching element such as a FET (Field Effect Transistor).

[0053] The operation circuit 13 is, for example, a microcontroller including a CPU, a ROM, and a RAM. Figure 2 As shown, the operation circuit 13 is electrically connected to the detection circuit 113. The operation circuit 13 receives the first signal Sig1 from the detection circuit 113 at a predetermined sampling rate. The operation circuit 13 receives the first signal Sig1 from the detection circuit 113 at intervals of, for example, 50 msec. The operation circuit 13 calculates the magnitude of the load applied to the elastic member 10 based on the first signal Sig1, for example.

[0054] like Figure 2 As shown, the operation circuit 13 is electrically connected to the switch 12. The operation circuit 13 sends a signal related to a command for switching the switch 12 on / off to the switch 12. For example, in the case where the switch 12 is a FET, the operation circuit 13 sends a signal related to a command for switching the gate of the FET on / off to the FET. The switch 12 switches the switch 12 on / off based on the signal received from the operation circuit 13. After sending a signal related to a command for turning the switch 12 on to the switch 12, the operation circuit 13 sends a signal related to a command for turning the switch 12 off to the switch 12.

[0055] In the present embodiment, the operation circuit 13 turns on the switch 12 when determining that the elastic member 10 is charged. The operation circuit 13 determines whether the elastic member 10 is charged based on the first signal Sig1 received from the first sensor 11. Specifically, the operation circuit 13 determines whether the elastic member 10 is charged by investigating how the value of the first signal Sig1 decays.

[0056] Hereinafter, the process of determining whether the elastic member 10 is charged (hereinafter referred to as the process P) in the calculation circuit 13 will be described with reference to the drawings. Figure 6 1 is a diagram showing an example of the first signal Sig1 generated due to the elastic member 10 being charged. Figure 7 : is a diagram showing an example of the first signal Sig1 generated when the elastic member 10 is deformed so as to be twisted around the central axis CAX. Figure 6 and Figure 7 The horizontal axis in represents time. Figure 6 and Figure 7 The vertical axis in represents the value of the first signal Sig1.

[0057] like Figure 6 and Figure 7 As shown, the attenuation mode of the value of the first signal Sig1 generated by the deformation of the elastic member 10 is different from the attenuation mode of the value of the first signal Sig1 generated by the charge of the elastic member 10. The value of the first signal Sig1 generated by the charge of the elastic member 10 is attenuated based on the following formula 1. On the other hand, the value of the first signal Sig1 generated by the deformation of the elastic member 10 is not attenuated based on the formula 1.

[0058] [Number 1]

[0059]

[0060] Vt0 in Formula 1 represents the value of the first signal Sig1 output from the first sensor 11 at the reference time. The reference time refers to the time when the operation circuit 13 receives the first signal Sig1 from the first sensor 11. dt in Formula 1 represents the time before or after the reference time. a in Formula 1 represents the time constant in the sensor module 1 having the RC circuit. V(dt) in Formula 1 represents the value of the first signal Sig1 calculated based on Formula 1. For example, when Vt0 is 2.0 V, dt is after 1 second, and a is 3 seconds, V(dt) is approximately 1.4 V based on Formula 1.

[0061] The operation circuit 13 determines whether the elastic member 10 is charged by comparing the calculation result obtained according to the formula 1 with the value of the first signal Sig1. Figure 6 and Figure 7 As shown, the calculation circuit 13 calculates the calculated value MD representing the attenuation mode of the first signal Sig1 based on the equation 1. Figure 6 As shown, the calculation circuit 13 obtains the calculated value MD by substituting the value of the first signal Sig1 at the time p1 (reference time) into the equation 1.

[0062] The calculation circuit 13 determines whether the calculated value MD is consistent with the value of the first signal Sig1. If the calculated value MD is consistent with the value of the first signal Sig1, the calculation circuit 13 determines that the elastic member 10 is charged. Figure 6 In the example shown, the calculated value MD coincides with the value of the first signal Sig1 , and therefore, the calculation circuit 13 determines that the elastic member 10 is charged.

[0063] On the other hand, Figure 7 In the example shown, the calculation circuit 13 obtains the calculated value MD by substituting the value of the first signal Sig1 at the time q1 (reference time) into the equation 1. Figure 7 In the example shown, the calculated value MD does not coincide with the value of the first signal Sig1 , and therefore, the calculation circuit 13 determines that the elastic member 10 is not charged.

[0064] Hereinafter, a series of processes of processing P will be described with reference to the drawings. Figure 8 2 is a flowchart showing an example of the process P executed by the calculation circuit 13 . Fig. 9 1 is a diagram showing the waveform of the first signal Sig1 when the arithmetic circuit 13 executes the process P.

[0065] For example, when the power of the arithmetic circuit 13 is turned on, the arithmetic circuit 13 starts to perform the processing P( Figure 8 :start).

[0066] After starting, the calculation circuit 13 calculates the calculation value MD ( Figure 8 :Step S11). In this embodiment, as Fig. 9 As shown, the operation circuit 13 calculates the calculated value MD1 representing the value of the first signal Sig1 during the period PE1 after the time u1 (reference time) based on the value of the first signal Sig1 at the time u1. Specifically, the operation circuit 13 calculates the calculated value MD1 of the period PE1 by substituting the value of the first signal Sig1 at the time u1 into the formula 1. The period PE1 is the period between the time u1 and the time t1 after the time u1. The length of the time of the period PE1 is, for example, 2.5 seconds. In this case, the operation circuit 13 calculates the calculated value MD1 representing the value of the first signal Sig1 between the time u1 and the time t1 after 2.5 seconds.

[0067] After step S11, the operation circuit 13 compares the calculated value MD1 with the value of the first signal Sig1 received by the operation circuit 13 from the first sensor 11 during the period PE1 ( Figure 8 :Step S12). Specifically, the operation circuit 13 compares the calculated value MD1 with the value of the first signal Sig1 received by the operation circuit 13 from the first sensor 11 during the period PE1 at the determination time after the reference time. The determination time is the last time in the period PE1. Therefore, the operation circuit 13 performs the processing of step S12 at time t1 (determination time).

[0068] In the present embodiment, the operation circuit 13 determines whether the value of the first signal Sig1 at each time point during the period PE1 is within a predetermined threshold value. The predetermined threshold value is, for example, within ±10% of the calculated value MD1. Therefore, the operation circuit 13 determines whether the elastic member 10 is charged based on the calculated value MD1 and the value of the first signal Sig1 received by the operation circuit 13 from the first sensor 11 during the period PE1 (the period after the reference time).

[0069] The calculation circuit 13 continuously performs the processing of steps S11 and S12 for a predetermined number of times (hereinafter referred to as the acquisition number of times) ( Figure 8 :Step S13). For example, the operation circuit 13 performs the processing of steps S11 and S12 10 times continuously. Fig. 9 As shown, after calculating the calculated value MD1, the operation circuit 13 calculates the calculated value MD2 at the time u2 (reference time) after the time u1. As an example, when the sampling rate of the operation circuit 13 is 50msec, the time u2 is the time 50msec after the time u1. The operation circuit 13 calculates the calculated value MD2 based on the value of the first signal Sig1 at the time u2. The calculated value MD2 represents the value of the first signal Sig1 during the period PE2 between the time u2 and the time t2 after the time u2. The operation circuit 13 compares the value of the first signal Sig1 received during the period PE2 at the time t2 with the calculated value MD2. The operation circuit 13 repeats the above-mentioned process until "the number of acquisitions = 10".

[0070] After step S13, the operation circuit 13 detects the number of periods during which the value of the first signal Sig1 coincides with the calculated value MD (hereinafter referred to as the count number) ( Figure 8 : Step S14). Specifically, in one cycle from period PE1 to period PE10, the number of periods in which the value of the first signal Sig1 is consistent with the calculated values ​​MD1 to MD10 is detected. Fig. 9 In the example shown, the value of the first signal Sig1 does not match the calculated values ​​MD1 to MD10 in all the periods from the period PE1 to the period PE10. In this case, the calculation circuit 13 calculates "the number of counts = 0".

[0071] When the counted number is less than a predetermined number (hereinafter referred to as the determination number) ( Figure 8 : Step S15 is "No"), the calculation circuit 13 determines that the elastic member 10 is not charged ( Figure 8 :Step S16). For example, when the counted number is less than 7, the operation circuit 13 determines that the elastic member 10 is not charged. Fig. 9In the example shown, the calculation circuit 13 calculates “count number=0” in the period PE1 to the period PE10 . Therefore, the calculation circuit 13 determines that the elastic member 10 is not charged at time t10 .

[0072] When the counted number is greater than the specified number ( Figure 8 : Step S15 is "Yes"), the calculation circuit 13 determines that the elastic member 10 is charged ( Figure 8 : Step S17) For example, when the count number is 7 or more, the calculation circuit 13 determines that the elastic member 10 is charged.

[0073] For example, Fig. 9 As shown, the operation circuit 13 determines whether the value of the first signal Sig1 is consistent with the calculated values ​​MD15 to MD25 in one cycle from period PE15 to period PE25, similarly to one cycle from period PE1 to period PE10. Periods PE15 to PE25 are periods after period PE10. Fig. 9 In the example shown, the value of the first signal Sig1 matches the calculated values ​​MD15 to MD25 in all periods from period PE15 to period PE25. Therefore, the calculation circuit 13 calculates the count number as "10". In this case, the calculation circuit 13 determines that the elastic member 10 is charged at time t25 (determination time).

[0074] Furthermore, the calculation circuit 13 calculates the calculation value MD10 at a time before the time t10 by a length corresponding to the time length of the period PE10. Similarly, the calculation circuit 13 calculates the calculation values ​​MD15 to MD25.

[0075] When the calculation circuit 13 determines that the elastic member 10 is charged, the switch 12 is turned on ( Figure 8 : Step S18). Fig. 9 In the example shown, the calculation circuit 13 determines that the elastic member 10 is charged at time t25 (determination time). Therefore, the calculation circuit 13 turns on the switch 12 at time t25. In this case, at time t25, the value of the first signal Sig1 matches the reference potential VE.

[0076] The operation circuit 13 repeats the processing of step S11 to step S18. For example, the operation circuit 13 executes the processing of step S11 to step S18 every time the first signal Sig1 is received from the first sensor 11 at a predetermined sampling interval. For example, after the operation circuit 13 executes the processing P with the period PE1 to the period PE10 as one cycle, it executes the processing P with the period PE2 to the period PE11 (not shown) as one cycle.

[0077] The arithmetic circuit 13 ends the processing P( Figure 8 :Finish).

[0078] (Effect)

[0079] According to the sensor module 1, the first sensor 11 is not prone to malfunction. In the present embodiment, the first sensor 11 is attached to the elastic member 10 in such a manner that the lower electrode 112 as the signal electrode is close to the elastic member 10. In the present embodiment, the elastic member 10 is in contact with the lower electrode 112 as the signal electrode via an adhesive. The elastic member 10 contains a resin that is easily charged. The lower electrode 112 is charged, for example, due to the influence of the charge of the elastic member 10. In this case, the potential difference between the upper electrode 110 and the lower electrode 112 changes. As a result, even if the elastic member 10 is not deformed, the first sensor 11 may generate a first signal Sig1 having a negative or positive polarity relative to the reference potential VE.

[0080] Therefore, the sensor module 1 according to the present embodiment includes a switch 12 having a function of short-circuiting the upper electrode 110 and the lower electrode 112. When the switch 12 is turned on, the potential difference between the upper electrode 110 and the lower electrode 112 caused by the elastic member 10 being charged becomes zero. Thus, when the elastic member 10 is not deformed, the first sensor 11 does not output the first signal Sig1 having a positive or negative polarity with respect to the reference potential VE. In other words, the first sensor 11 is less likely to erroneously output the first signal Sig1 indicating that the elastic member 10 is deformed even though the elastic member 10 is not deformed.

[0081] In the sensor module 1, the operation circuit 13 determines whether the elastic member 10 is charged based on the first signal Sig1. In this case, when the elastic member 10 is not charged, the operation circuit 13 does not turn on the switch 12. Therefore, it is less likely that the first sensor 11 cannot detect the deformation of the elastic member 10 due to the switch 12 being turned on unnecessarily.

[0082] The operation circuit 13 determines whether the value of the first signal Sig1 is consistent with the calculated value MD, for example, by taking the period PE1 to the period PE10 as one cycle. Therefore, for example, even if the first sensor 11 outputs an abnormal output value in one of the periods PE1 to PE10, the operation circuit 13 can accurately determine whether the elastic member 10 is charged.

[0083] For example, when the elastic member 10 is deformed, the first sensor 11 outputs the first signal Sig1. At this time, the value of the first signal Sig1 output from the first sensor 11 may be consistent with the calculated value MD. In the present embodiment, the operation circuit 13, for example, regards the period PE1 to the period PE10 as one cycle to determine whether the value of the first signal Sig1 is consistent with the calculated value MD. Thus, when the value of the first signal Sig1 output from the first sensor 11 is instantaneously consistent with the calculated value MD, the operation circuit 13 is not likely to mistakenly determine that the elastic member 10 is charged.

[0084] For example, the operation circuit 13 determines whether the elastic member 10 is charged by taking 10 periods PE1 to PE10 as one cycle. In this case, the time required for the operation circuit 13 to make this determination is, for example, 0.5 seconds (sampling rate (seconds) × 10 (times)). Therefore, the operation circuit 13 can determine whether the elastic member 10 is charged in a short time.

[0085] [Modification 1]

[0086] Hereinafter, a sensor module 1 a according to Modification 1 will be described with reference to the drawings. Fig.10 It is a perspective view showing the appearance of a sensor module 1 a according to Modification 1. Fig.11 1 is a diagram showing an example of connection among the switch 12 , the calculation circuit 13 , and the second sensor 14 a . Fig.12 : is a figure which shows the 2nd sensor 14a.

[0087] The sensor module 1a is different from the sensor module 1 in that it further includes a second sensor 14a. Fig.10 As shown, the second sensor 14a is in contact with the elastic member 10. The second sensor 14a is in contact with the outer peripheral surface of the elastic member 10. Fig.11 As shown, the second sensor 14 a includes a second sensor upper electrode 140 , a film 141 , a second sensor lower electrode 142 , and a detection circuit 143 .

[0088] In this modification, the second sensor 14a does not output a signal according to the deformation of the elastic member 10. As an example, the film 141 does not have piezoelectricity. The film 141 does not generate an electric charge corresponding to the deformation of the elastic member 10. Such a film 141 is, for example, a PET film. Fig.12 As shown, the film 141 has an upper main surface SF1 a and a lower main surface SF2 a which are arranged in this order in the downward direction.

[0089] The second sensor upper electrode 140 is a reference electrode connected to the reference potential VE. The second sensor upper electrode 140 is fixed to the upper main surface SF1 a by an adhesive (not shown) such as OCA. Therefore, the second sensor upper electrode 140 is located on the film 141 .

[0090] The second sensor lower electrode 142 is a signal electrode and is fixed to the lower main surface SF2 a by an adhesive (not shown) such as OCA. The second sensor lower electrode 142 is located under the film 141 .

[0091] like Fig.11 As shown, the detection circuit 143 is electrically connected to the second sensor upper electrode 140 and the second sensor lower electrode 142. The detection circuit 143 converts the charge generated by the film 141 into a voltage signal.

[0092] The second sensor 14a outputs a signal based on the potential difference between the second sensor upper electrode 140 and the second sensor lower electrode 142. The second sensor 14a outputs a signal (hereinafter referred to as a second signal) based on the charge of the elastic member 10. The second sensor lower electrode 142, which is a signal electrode, is in contact with the elastic member 10. The second sensor lower electrode 142 is charged by being affected by the charge of the elastic member 10. As a result, the potential difference between the second sensor upper electrode 140 and the second sensor lower electrode 142 changes.

[0093] In this modification, the operation circuit 13 determines whether the elastic member 10 is charged based on the second signal. For example, the operation circuit 13 compares the value of the second signal with a predetermined threshold value. When the value of the second signal becomes greater than the predetermined threshold value, the operation circuit 13 determines that the elastic member 10 is charged. When the operation circuit 13 determines that the elastic member 10 is charged, the switch 12 is turned on.

[0094] (Effect)

[0095] When the elastic member 10 is deformed, the second sensor 14a does not output the second signal. When the elastic member 10 is charged, the second sensor 14a outputs the second signal. The operation circuit 13 determines whether the elastic member 10 is charged based on the second signal. Thus, the operation circuit 13 can reliably determine whether the signal is generated due to the deformation of the elastic member 10 or the signal is generated due to the charging of the elastic member 10.

[0096] The procedure related to the process of comparing the value of the second signal with the threshold value (hereinafter referred to as process Q) in this modification example is simpler than the procedure related to process P. Therefore, the load imposed on the operation circuit 13 when the operation circuit 13 executes the procedure related to process Q is smaller than the load imposed on the operation circuit 13 when the operation circuit 13 executes the procedure related to process P.

[0097] [Modification 2]

[0098] Next, a sensor module 1 b (not shown) according to a second modification will be described with reference to the drawings. Fig.13 This is a diagram showing an example of processing by the calculation circuit 13b included in the sensor module 1b according to the second modification. Fig.13 The horizontal axis in represents time. Fig.13 The vertical axis in represents the value of the first signal Sig1. Fig.13 In the example shown, the calculation circuit 13b determines that the elastic member 10 is charged at time w1. Fig.13 In the example shown, time w2 is a time after time w1.

[0099] The sensor module 1b is different from the sensor module 1 in that it includes a calculation circuit 13b that is different from the calculation circuit 13. When determining that the elastic member 10 is charged, the calculation circuit 13b further performs a process of shifting the value of the first signal Sig1.

[0100] Specifically, the operation circuit 13b determines whether the elastic member 10 is charged based on the first signal Sig1. Fig.13 In the example shown, the operation circuit 13 determines that the elastic member 10 is charged at the time w1. In this case, the operation circuit 13b calculates the difference DV between the reference potential VE and the value of the first signal Sig1 at the time w1 (charged time) when the elastic member 10 is determined to be charged. For example, when the value of the first signal Sig1 at the time w1 is 2.0V and the reference potential VE is 0V, the difference DV is 2.0V.

[0101] The operation circuit 13 calculates the value of the first signal Sig1 at a time after the time w1 based on the difference value DV. Specifically, the operation circuit 13 calculates the difference between the difference value DV and the value of the first signal Sig1 received from the detection circuit 113 at a time after the time w1. The operation circuit 13 estimates the difference as the value of the first signal Sig1. For example, at a time w2 after the time w1, the operation circuit 13 receives the first signal Sig1 having a value of "2.0V". In this case, the operation circuit 13 estimates the value of the first signal Sig1 at the time w2 as "0V" based on the "difference value: 2.0V".

[0102] The calculation circuit 13b turns on the switch 12 when it is determined that the elastic member 10 has been de-energized for a predetermined time or when the sensor module 1b is restarted. After turning on the switch 12, the calculation circuit 13b returns the reference to the value before the shift. Fig.13 In the example shown, the operation circuit 13 b restores the difference value DV from “2.0 V” to “0.0 V”, for example. After restoring the reference value to the value before the offset, the operation circuit 13 b turns off the switch 12 .

[0103] (Effect)

[0104] When the elastic member 10 is deformed when the switch 12 is in the on state, the voltage generated by the first sensor 11 during the period when the switch 12 is in the on state becomes invalid. Here, for example, the switch 12 is disconnected when the elastic member 10 is deformed. After the switch 12 is disconnected, the value of the first signal Sig1 output from the first sensor 11 will be offset by an amount equivalent to the amount of voltage that has become invalid. As a result, the value of the first signal Sig1 output from the first sensor 11 after the switch 12 is disconnected may have an error. However, when the operation circuit 13b determines that the elastic member 10 is charged, the value of the first signal Sig1 is calculated based on the difference DV. That is, the operation circuit 13 calculates the value of the first signal Sig1 taking into account the error. As a result, the accuracy of the operation circuit 13b in detecting the deformation of the elastic member 10 is improved.

[0105] When the elastic member 10 is charged, the operation circuit 13b does not turn on the switch 12. When the elastic member 10 is charged, the operation circuit 13b calculates the first signal Sig1 based on the difference DV. Therefore, even if the elastic member 10 is charged, the operation circuit 13b can accurately detect the deformation of the elastic member 10.

[0106] [Variation 3]

[0107] Next, a sensor module 1 c according to a third modification will be described with reference to the drawings. Fig.14 This is a block diagram showing an example of a sensor module 1 c according to Modification 3.

[0108] like Fig.14 As shown in FIG. 1 , the sensor module 1 c is different from the sensor module 1 in that it further includes an LED 15 and a power button 16 . The LED 15 and the power button 16 are electrically connected to the calculation circuit 13 .

[0109] The LED 15 corresponds to a display device for displaying information corresponding to the deformation of the elastic member in the present invention. For example, the brightness of the LED 15 changes according to the deformation of the elastic member 10. For example, when the deformation of the elastic member 10 is large, the operation circuit 13 increases the brightness of the LED 15 (makes it brighter), and when the deformation of the elastic member 10 is small, the operation circuit 13 reduces the brightness of the LED 15 (makes it darker).

[0110] In addition, the calculation circuit 13 can change the color of the LED 15 in addition to changing the brightness of the LED 15 according to the deformation of the elastic member 10, and can also change the number of LEDs that are lit when the LED 15 is composed of a plurality of LEDs. In addition, the calculation circuit 13 can also change the flashing speed of the LED according to the deformation of the elastic member 10.

[0111] The sensor module 1c may include an organic EL display or a liquid crystal display instead of the LED 15. In this case, the organic EL display or the liquid crystal display displays the deformation amount of the elastic member 10 as information corresponding to the deformation of the elastic member 10 in numerical form, for example.

[0112] The power button 16 is an example of an interface in the present invention. The power button 16 receives an instruction from the user to turn the power of the sensor module 1c on or off. By pressing the power button 16, the power of the sensor module 1c is switched on / off.

[0113] In this modification, the calculation circuit 13 turns off the power of the sensor module 1c when it is determined that the elastic member 10 is charged. When the power button 16 is pressed after the power of the sensor module 1c is turned off, the power is turned on. When the power is turned on, the calculation circuit 13 turns on the switch 12.

[0114] Assuming that the elastic member 10 is charged and the switch 12 is turned on when the user twists the elastic member 10, the potential difference between the upper electrode 110 and the lower electrode 112 is reset to zero in a state where the elastic member 10 is deformed. Therefore, when the user releases the twisting operation and the elastic member 10 returns to the shape before deformation, the first sensor 11 may output a signal detecting the potential difference between the upper electrode 110 and the lower electrode 112 even though the elastic member 10 is not deformed.

[0115] In the sensor module 1c, when the power of the sensor module 1c is disconnected, the LED 15 goes out. Therefore, the user recognizes that the power of the sensor module 1c is disconnected. When the power is disconnected, the user releases the twisting operation and presses the power button 16. When the power is turned on by the power button 16, the operation circuit 13 turns on the switch 12 in a state where the elastic member 10 is not deformed. In a state where the elastic member 10 is not deformed, the potential difference between the upper electrode 110 and the lower electrode 112 is a potential difference caused by charging, and when the switch 12 is turned on, the potential difference can be made zero. Therefore, even if the elastic member 10 is charged when the user twists the elastic member 10, the first sensor 11 can more accurately detect the deformation amount of the elastic member 10.

[0116] [Variation 4]

[0117] Next, a sensor module 1d according to a fourth modification will be described with reference to the drawings. Fig.15 This is a block diagram showing an example of a sensor module 1 d according to Modification 4.

[0118] like Fig.15As shown in FIG. 1 , the sensor module 1d is different from the sensor module 1c in that it further includes an alarm LED 17. Fig.15 As shown, the alarm LED 17 is electrically connected to the calculation circuit 13 .

[0119] When the calculation circuit 13 determines that the elastic member 10 is charged, the alarm LED 17 is turned on to notify the user that the elastic member 10 is charged. That is, the alarm LED 17 functions as an example of a notification unit.

[0120] Thus, the user can recognize that the elastic member 10 is charged. The user releases the twisting operation on the elastic member 10 and presses the power button 16. As a result, the power of the sensor module 1d is turned on when the elastic member 10 is not deformed. In addition, when the power of the sensor module 1d is turned on, the operation circuit 13 turns on the switch 12. Therefore, similarly to the sensor module 1c, when the elastic member 10 is not deformed, the potential difference between the upper electrode 110 and the lower electrode 112 is the potential difference caused by the charge, and when the switch 12 is turned on, the potential difference can be made zero. Therefore, even if the elastic member 10 is charged when the user twists the elastic member 10, the first sensor 11 can accurately detect the deformation amount of the elastic member 10.

[0121] In addition, the notification unit in the present application may be, for example, a speaker having a function of emitting sound, or a vibrator having a function of vibrating the sensor module.

[0122] [Other embodiments]

[0123] The sensor module according to the present invention is not limited to the sensor modules 1 and 1a to 1d, and can be modified within the scope of the gist thereof. In addition, the structures of the sensor modules 1 and 1a to 1d can be arbitrarily combined.

[0124] Furthermore, the elastic member 10 may not necessarily be in the shape of a rod.

[0125] Furthermore, the elastic member 10 does not necessarily need to be in a cylindrical shape.

[0126] Alternatively, the switch 12 may include two FETs connected in series. This can suppress leakage current generated between the upper and lower electrodes of the sensor modules 1 and 1a to 1d when the switch 12 is turned off, thereby improving the accuracy of the first sensor 11 in detecting the deformation of the elastic member 10 .

[0127] In addition, the sensor module 1 can also be used in electronic devices such as smart phones.

[0128] In addition, the material of the elastic member 10 may be a resin other than acrylic resin.

[0129] In addition, the upper electrode 110 does not necessarily need to be connected to the ground potential.

[0130] In addition, the first sensor 11 does not necessarily need to be in contact with the outer peripheral surface of the elastic member 10. For example, the elastic member 10 has a cylindrical shape having an inner peripheral surface and an outer peripheral surface. In this case, the first sensor 11 may be in contact with the inner peripheral surface of the elastic member 10.

[0131] The process P of determining whether the elastic member 10 is charged in the sensor module 1 a is an example. Therefore, the sensor module 1 a does not need to determine whether the elastic member 10 is charged by the process P.

[0132] Furthermore, the calculation circuit 13 does not necessarily have to switch the switch 12 on / off based on the process P. For example, the calculation circuit 13 may send a signal related to a command for turning on the switch 12 to the switch 12 at a predetermined interval (for example, once every 10 seconds).

[0133] Furthermore, as long as the second sensor 14 a does not output the second signal based on the torsional deformation of the elastic member 10 , the film 141 may have piezoelectricity.

[0134] In the first embodiment, the conditions of the acquisition number, the determination number, and the count number can be adjusted. For example, in the first embodiment, the acquisition number does not have to be "10". For example, in the first embodiment, the determination number does not have to be "7".

[0135] In the first embodiment, the calculation circuit 13 may determine whether the elastic member 10 is charged based on the ratio (%) of the counted number to the acquisition number. For example, the calculation circuit 13 may determine that the elastic member 10 is charged when the ratio of the counted number to the acquisition number is 80% or more.

[0136] In the first embodiment, the calculation circuit 13 may determine that the elastic member 10 is not charged based on conditions other than the determination number and the count number.

[0137] The present invention has the following construction. (1)

[0139] A sensor module, comprising:

[0140] an elastic member comprising a resin;

[0141] a first sensor that contacts the elastic member and includes an upper electrode, a piezoelectric film, and a lower electrode; and

[0142] switch,

[0143] wherein the first sensor outputs a first signal corresponding to the deformation of the elastic member,

[0144] The switch has a function of short-circuiting the upper electrode and the lower electrode.

[0145] The lower electrode is a signal electrode. (2)

[0147] The sensor module according to (1), wherein:

[0148] The upper electrode is a reference electrode connected to a reference potential. (3)

[0150] The sensor module according to (1) or (2), wherein:

[0151] The first sensor outputs the first signal based on a potential difference between the upper electrode and the lower electrode. (4)

[0153] The sensor module according to any one of (1) to (3), wherein:

[0154] The sensor module further includes a computing circuit.

[0155] The arithmetic circuit switches the switch on and off based on the first signal. (5)

[0157] The sensor module according to (4), wherein:

[0158] The operation circuit determines whether the elastic member is charged based on the first signal received from the first sensor,

[0159] The arithmetic circuit turns on the switch when determining that the elastic member is charged. (6)

[0161] The sensor module according to (4), wherein:

[0162] The sensor module further includes a power supply and an interface, wherein the interface is used to receive an instruction to turn on the power supply.

[0163] The operation circuit determines whether the elastic member is charged based on the first signal received from the first sensor,

[0164] When the calculation circuit determines that the elastic member is charged, the power supply is turned off.

[0165] When the power source is turned on through the interface after the power source is turned off, the arithmetic circuit turns on the switch. (7)

[0167] The sensor module according to (6), wherein:

[0168] A display device is further provided, the display device displays information corresponding to the deformation of the elastic member, and the display of the display device is turned off when the power is turned off. (8)

[0170] The sensor module according to (4), wherein:

[0171] The sensor module further includes a power supply and a notification unit, wherein the notification unit is used to notify that the elastic member is charged.

[0172] The operation circuit determines whether the elastic member is charged based on the first signal received from the first sensor,

[0173] When the calculation circuit determines that the elastic member is charged, the calculation circuit notifies the elastic member of the charge through the notification unit.

[0174] After the notification, the operation circuit turns on the switch. (9)

[0176] The sensor module according to any one of (5) to (8), wherein:

[0177] The calculation circuit calculates a calculated value indicating a value of the first signal during a period after the reference time based on the value of the first signal at a reference time when the calculation circuit receives the first signal from the first sensor.

[0178] The calculation circuit determines whether the elastic member is charged based on the calculated value and a value of the first signal received by the calculation circuit from the first sensor during a period after the reference time. (10)

[0180] The sensor module according to any one of (1) to (3), wherein:

[0181] The sensor module further includes a computing circuit.

[0182] The operation circuit determines whether the elastic member is charged based on the first signal.

[0183] When the calculation circuit determines that the elastic member is charged, the calculation circuit calculates a difference between a reference potential and a value of the first signal at a charging time when the elastic member is determined to be charged.

[0184] The operation circuit calculates a value of the first signal at a time after the charging time based on the difference. (11)

[0186] The sensor module according to any one of (1) to (3), wherein:

[0187] The sensor module further comprises a second sensor,

[0188] The second sensor is in contact with the elastic member,

[0189] The second sensor includes a film, a second sensor upper electrode and a second sensor lower electrode,

[0190] The second sensor outputs a second signal based on the electrification of the elastic member. (12)

[0192] The sensor module according to (11), wherein:

[0193] The sensor module further includes a computing circuit.

[0194] The operation circuit determines whether the elastic member is charged based on the second signal.

[0195] The arithmetic circuit turns on the switch when determining that the elastic member is charged. (13)

[0197] The sensor module according to any one of (1) to (12), wherein:

[0198] The elastic member is in the shape of a rod. (14)

[0200] The sensor module according to any one of (1) to (13), wherein:

[0201] The elastic member is in the shape of a rod having a central axis extending in the left-right direction.

[0202] The elastic member is deformed around the central axis,

[0203] The first sensor detects deformation of the elastic member about the central axis. (15)

[0205] The sensor module according to (14), wherein:

[0206] The elastic member is deformed in a twisted manner about the central axis.

[0207] Description of Reference Numerals

[0208] 1, 1a~1d: sensor module; 10: elastic member; 11: first sensor; 110: upper electrode; 111: piezoelectric film; 112: lower electrode; 12: switch; 13, 13b: operation circuit; Sig1: first signal.

Claims

1. A sensor module comprising: an elastic member comprising a resin; a first sensor that contacts the elastic member and includes an upper electrode, a piezoelectric film, and a lower electrode; and switch, in, The first sensor outputs a first signal corresponding to the deformation of the elastic member, The switch has a function of short-circuiting the upper electrode and the lower electrode. The lower electrode is a signal electrode.

2. The sensor module according to claim 1, wherein: The upper electrode is a reference electrode connected to a reference potential.

3. The sensor module according to claim 1 or 2, wherein: The first sensor outputs the first signal based on a potential difference between the upper electrode and the lower electrode.

4. The sensor module according to any one of claims 1 to 3, wherein: The sensor module further includes a computing circuit. The arithmetic circuit switches the switch on and off based on the first signal.

5. The sensor module according to claim 4, wherein: The operation circuit determines whether the elastic member is charged based on the first signal received from the first sensor, The arithmetic circuit turns on the switch when determining that the elastic member is charged.

6. The sensor module according to claim 4, wherein: The sensor module further includes a power supply and an interface, wherein the interface is used to receive an instruction to turn on the power supply. The operation circuit determines whether the elastic member is charged based on the first signal received from the first sensor, When the calculation circuit determines that the elastic member is charged, the power supply is turned off. When the power source is turned on through the interface after the power source is turned off, the arithmetic circuit turns on the switch.

7. The sensor module according to claim 6, wherein: A display device is further provided, the display device displays information corresponding to the deformation of the elastic member, and the display of the display device is turned off when the power is turned off.

8. The sensor module according to claim 4, wherein: The sensor module further includes a power supply and a notification unit, wherein the notification unit is used to notify that the elastic member is charged. The operation circuit determines whether the elastic member is charged based on the first signal received from the first sensor, When the calculation circuit determines that the elastic member is charged, the calculation circuit notifies the elastic member of the charge through the notification unit. After the notification, the operation circuit turns on the switch.

9. The sensor module according to any one of claims 5 to 8, wherein: The calculation circuit calculates a calculated value indicating a value of the first signal during a period after the reference time based on the value of the first signal at a reference time when the calculation circuit receives the first signal from the first sensor. The calculation circuit determines whether the elastic member is charged based on the calculated value and a value of the first signal received by the calculation circuit from the first sensor during a period after the reference time.

10. The sensor module according to any one of claims 1 to 3, wherein: The sensor module further includes a computing circuit. The operation circuit determines whether the elastic member is charged based on the first signal. When the calculation circuit determines that the elastic member is charged, the calculation circuit calculates a difference between a reference potential and a value of the first signal at a charging time when the elastic member is determined to be charged. The operation circuit calculates a value of the first signal at a time after the charging time based on the difference.

11. The sensor module according to any one of claims 1 to 3, wherein: The sensor module further comprises a second sensor, The second sensor is in contact with the elastic member, The second sensor includes a film, a second sensor upper electrode, and a second sensor lower electrode, and the second sensor outputs a second signal based on the electrification of the elastic member.

12. The sensor module according to claim 11, wherein: The sensor module further includes a computing circuit. The operation circuit determines whether the elastic member is charged based on the second signal. The arithmetic circuit turns on the switch when determining that the elastic member is charged.

13. The sensor module according to any one of claims 1 to 12, wherein: The elastic member is in the shape of a rod.

14. The sensor module according to any one of claims 1 to 13, wherein: The elastic member is in the shape of a rod having a central axis extending in the left-right direction. The elastic member is deformed around the central axis, The first sensor detects deformation of the elastic member about the central axis.

15. The sensor module according to claim 14, wherein: The elastic member is deformed in a twisted manner about the central axis.

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