JP6020755B1 - Pressure sensor device, pressure sensor method, and storage medium - Google Patents

Abstract

A pressure sensor device and a pressure sensor method are provided that can suppress changes in sensor characteristics over time. A pressure sensor device includes a sensor unit having a pressure-sensitive conductor configured to change an electric resistance according to an applied pressure, and a sensor for obtaining information on the electric resistance of the pressure-sensitive conductor. And a control unit 50 that performs a first process for applying a voltage to the unit and a second process for applying a voltage to the sensor unit. During the first process, the control unit applies a voltage to the sensor unit such that the voltage applied to the pressure-sensitive conductor becomes the first voltage. During the second process, the control unit applies a voltage to the sensor unit such that the voltage applied to the pressure-sensitive conductor becomes the second voltage in the direction opposite to the first voltage. [Selection] Figure 1

Description

  Embodiments of the present disclosure relate to a pressure sensor device and a pressure sensor method for detecting pressure. The embodiment of the present disclosure also relates to a storage medium storing a program for executing the pressure sensor method.

  Conventionally, pressure sensor devices using pressure-sensitive conductors are known. The pressure-sensitive conductor is a pressure-sensitive body configured such that the electrical resistance in the direction in which pressure is applied changes according to the applied pressure. The pressure-sensitive conductor includes, for example, rubber such as silicone rubber and a plurality of particles having conductivity such as carbon added to the rubber. In this case, when pressure is applied to the pressure-sensitive conductor, the rubber portion is distorted and the particles come into contact with each other at the distorted portion. For this reason, the number of particles in a contact state increases, and as a result, the electric resistance of the pressure-sensitive conductor decreases. That is, there is a relationship between the pressure applied to the pressure-sensitive conductor and the electrical resistance of the pressure-sensitive conductor, in which the electrical resistance decreases as the pressure increases. Therefore, the value and distribution of the pressure applied to the pressure sensitive conductor can be calculated based on the measurement result of the electric resistance of the pressure sensitive conductor.

  By the way, it is known that the pressure-sensitive conductor has a problem that the relationship between the pressure applied to the pressure-sensitive conductor and the electric resistance of the pressure-sensitive conductor changes with time. For example, Patent Document 1 describes a problem that, when a constant pressure is continuously applied to a pressure-sensitive conductor, the electrical resistance of the pressure-sensitive conductor changes over time due to the creep characteristics of rubber. Therefore, in order to accurately calculate the pressure value using the pressure-sensitive conductor, the pressure value is corrected in consideration of the change in the characteristics of the pressure-sensitive conductor, or the characteristics of the pressure-sensitive conductor are changed. It is required to suppress the change itself. For example, Patent Document 1 proposes that two layers of pressure-sensitive conductors are provided, correction is performed based on the difference in current flowing in each layer, and pressure applied to the pressure-sensitive conductor is calculated. In Patent Document 2, it is proposed to suppress a change in characteristics of the pressure-sensitive conductor by arranging a spacer around the pressure-sensitive conductor.

JP 2013-140137 A JP-A-62-197729

  The methods proposed in Patent Document 1 and Patent Document 2 described above involve a complicated structure of the pressure sensor device, such as addition of a pressure-sensitive conductor layer or addition of a spacer. The method proposed in Patent Document 1 further complicates data analysis for calculating the pressure value.

  Embodiments of the present disclosure have been made in consideration of such points, and an object thereof is to provide a pressure sensor device and a pressure sensor method that can suppress changes in sensor characteristics over time. To do.

  One embodiment of the present disclosure is a pressure sensor device having a pressure-sensitive conductor configured to change an electric resistance in accordance with an applied pressure, and information on the electric resistance of the pressure-sensitive conductor. A first process for applying a voltage to the sensor unit, and a control unit for performing a second process for applying a voltage to the sensor unit. In the first process, the control unit The voltage applied to the pressure-sensitive conductor is applied to the sensor unit such that the voltage applied to the pressure-sensitive conductor becomes the first voltage, and the control unit applies the voltage applied to the pressure-sensitive conductor during the second process. However, the pressure sensor device applies a voltage to the sensor unit so that the second voltage has a direction opposite to the first voltage.

  In the pressure sensor device according to an embodiment of the present disclosure, the pressure-sensitive conductor is partitioned into a plurality of unit regions, and the sensor unit and the control unit are configured to have electrical resistances of the unit regions of the pressure-sensitive conductor. The information regarding each may be obtained.

  In the pressure sensor device according to an embodiment of the present disclosure, the sensor unit may include a plurality of transistors that are electrically connected to the corresponding unit regions of the pressure-sensitive conductor.

  In the pressure sensor device according to an embodiment of the present disclosure, during the second process, the control unit may simultaneously apply voltages applied to the plurality of unit regions of the pressure-sensitive conductor to be opposite to the first voltage. A voltage may be applied to the sensor unit so that the second voltage is in the direction of.

  In the pressure sensor device according to an embodiment of the present disclosure, in the second process, the control unit may sequentially apply voltages applied to the plurality of unit regions of the pressure-sensitive conductor in reverse to the first voltage. A voltage may be applied to the sensor unit so that the second voltage is in the direction of.

  In the pressure sensor device according to an embodiment of the present disclosure, the sensor unit includes a first electrode and a second electrode in contact with the pressure-sensitive conductor, and at least one of the first electrode and the second electrode is The conductive carbon material may be included.

  One embodiment of the present disclosure is a pressure sensor method for detecting a pressure applied to a pressure-sensitive conductor, based on an electric resistance of the pressure-sensitive conductor when a first voltage is applied to the pressure-sensitive conductor. A first processing step for calculating a pressure applied to the pressure-sensitive conductor, and a second processing step for applying a second voltage in a direction opposite to the first voltage to the pressure-sensitive conductor. A pressure sensor method is provided.

  One embodiment of the present disclosure is a non-transitory computer-readable storage medium storing a program for executing a pressure sensor method for detecting pressure applied to a pressure-sensitive conductor, The pressure sensor method includes a first processing step of calculating a pressure applied to the pressure sensitive conductor based on an electric resistance of the pressure sensitive conductor when a first voltage is applied to the pressure sensitive conductor; And a second processing step of applying a second voltage in a direction opposite to the first voltage to the pressure-sensitive conductor.

  According to the pressure sensor device of the embodiment of the present disclosure, it is possible to suppress changes in sensor characteristics over time.

FIG. 1 is a plan view illustrating a pressure sensor device according to an embodiment of the present disclosure. FIG. 2 is a plan view showing a sensor portion of the pressure sensor device. FIG. 3 is a cross-sectional view showing a case where the sensor portion of the pressure sensor device shown in FIG. 1 is cut in the III-III direction. 4 is an enlarged view showing a transistor of the sensor unit shown in FIG. FIG. 5 is a cross-sectional view illustrating a modified example of a transistor. FIG. 6 is a circuit diagram showing a transistor and a pressure-sensitive conductor of the sensor unit. FIG. 7 is a timing chart showing how pulses are sequentially applied to the word lines W1 to Wm. FIG. 8 is a timing diagram illustrating an example of a control method of the pressure sensor device according to the embodiment of the present disclosure. FIG. 9 is a diagram illustrating a result of measuring a current flowing through a pressure-sensitive conductor when a voltage is applied to the pressure-sensitive conductor through an electrode including a conductive carbon material. FIG. 10 is a diagram showing a result of measuring a current flowing through a pressure-sensitive conductor when a voltage is applied to the pressure-sensitive conductor through an electrode containing aluminum. FIG. 11 is a cross-sectional view illustrating a modified example of a transistor. FIG. 12 is a cross-sectional view illustrating a modified example of a transistor. FIG. 13 is a timing chart showing how pulses are sequentially applied to word lines W1 to Wm in the first modification. FIG. 14 is a timing chart showing an example of a method for controlling the pressure sensor device according to the first modification.

  Hereinafter, an embodiment of the present disclosure will be described with reference to FIGS. 1 to 8. In the drawings attached to the present specification, for the sake of illustration and ease of understanding, the scale, the vertical / horizontal dimension ratio, and the like are appropriately changed and exaggerated from those of the actual ones. Further, in this specification, the terms “base material” and “film” are not distinguished from each other only based on the difference in names. For example, the “substrate” is a concept including a member that can be called a sheet or a film. Furthermore, as used in this specification, the shape and geometric conditions and the degree thereof are specified. For example, terms such as “surface”, values of length and angle, etc. The interpretation should include the extent to which the functions of can be expected.

(Pressure sensor device)
First, the entire pressure sensor device 10 will be described with reference to FIG. As shown in FIG. 1, the pressure sensor device 10 includes a sensor unit 20 having a pressure-sensitive conductor 38 and a control unit 50 electrically connected to the sensor unit 20 via a cable 45. The control unit 50 is a part configured to perform a first process of applying a voltage to the sensor unit 20 so as to obtain information regarding the electrical resistance of the pressure-sensitive conductor 38. In addition to the first process, the control unit 50 is configured to perform a second process of applying a voltage in the opposite direction to the case of the first process to the sensor unit 20. In the following description, the first process is referred to as a sensor process, and the second process is referred to as a reset process.

  The control unit 50 includes an arithmetic device and a storage medium. The arithmetic device is, for example, a CPU. The storage medium is a memory such as a ROM or a RAM. The control unit 50 performs the sensor process and the reset process when the arithmetic device executes a program stored in the storage medium.

  Although the use of the pressure sensor device 10 is not particularly limited, for example, as one of the uses, it is conceivable to use the pressure sensor device 10 by being incorporated in an instrument that receives a load of a human body such as a bed.

(Sensor part)
Next, the sensor unit 20 will be described with reference to FIGS. 1 to 3. FIG. 2 is a plan view showing the sensor unit 20 in a state in which members such as the pressure-sensitive conductor 38 and the second electrode 39 described later are overlapped with the transistor 30 described later for convenience. 3 is a cross-sectional view showing a case where the sensor unit 20 of the pressure sensor device 10 shown in FIG. 1 is cut in the III-III direction.

  As shown in FIGS. 1 and 3, the sensor unit 20 includes a pressure-sensitive conductor 38 including a first surface 38a and a second surface 38b. The pressure-sensitive conductor 38 is configured such that the electric resistance value of the pressure-sensitive conductor 38 in the direction in which the pressure is applied changes according to the pressure applied to the pressure-sensitive conductor 38. The pressure-sensitive conductor 38 includes, for example, rubber such as silicone rubber and a plurality of particles having conductivity such as carbon added to the rubber. In FIG. 3, the surface of the pressure-sensitive conductor 38 that is located on the transistor 30 side is represented by reference numeral 38a, the surface that is located on the opposite side of the first surface 38a and to which the external force F is applied is represented by reference numeral 38b. It is represented. Note that the specific shapes of the first surface 38a and the second surface 38b are not particularly limited as long as the electrical resistance of the pressure-sensitive conductor 38 changes significantly according to the external force F applied to the sensor unit 20. . For example, the first surface 38a and the second surface 38b may be uneven or curved.

  Preferably, the pressure-sensitive conductor 38 is partitioned into a plurality of unit regions 38e in the direction in which the first surface 38a and the second surface 38b expand. As a result, the pressure applied to the sensor unit 20 can be calculated individually at a plurality of positions, and therefore the pressure distribution of the external force F applied to the sensor unit 20 can be calculated. Note that “section” means that the sensor unit 20 and the control unit 50 are configured so that information on the electrical resistance of the plurality of unit regions 38e of the pressure-sensitive conductor 38 can be individually obtained. Yes. For example, as shown in FIGS. 1 to 3, the sensor unit 20 includes a base material 21 and a plurality of transistors 30 formed on the base material 21. The plurality of transistors 30 are electrically connected to corresponding unit regions 38e of the pressure-sensitive conductor 38, respectively. For this reason, for example, by individually measuring the currents flowing through the plurality of transistors 30, it is possible to individually measure the electrical resistances of the unit regions 38 e electrically connected to the transistors 30.

  The structure of the unit region 38e is not particularly limited as long as information on the electrical resistance of the plurality of unit regions 38e can be obtained individually. For example, as shown in FIG. 3, two adjacent unit regions 38e may be connected. In other words, the pressure-sensitive conductor 38 may be provided continuously across the plurality of transistors 30. Alternatively, although not shown, two adjacent unit regions 38e may be physically separated.

  The configuration of the sensor unit 20 in plan view will be further described. As shown in FIGS. 1 and 2, the sensor unit 20 may further include a plurality of terminal units 24 arranged along the outer edge of the base material 21 and electrically connected to the transistor 30. As shown in FIGS. 1 and 2, the base material 21 includes a pair of first sides 22a extending along the first direction D1 and a pair of first sides extending along the second direction D2 orthogonal to the first direction D1. It may have a rectangular outer shape including two sides 22b. In this case, the plurality of transistors 30 may be arranged in a matrix along the first direction D1 and the second direction D2.

  In FIG. 1 and FIG. 2, dotted lines denoted by reference characters W1 to Wm represent word lines provided for transmitting a control signal for sequentially turning on each transistor 30. Each of the word lines W1 to Wm is electrically connected to gate terminals 31 (to be described later) of the plurality of transistors 30 arranged along the first direction D1. For example, the word line W1 is positioned on the lowermost side in FIG. 1 and FIG. 2 and is electrically connected to the gate terminals 31 of the plurality of transistors 30 arranged along the first direction D1. Therefore, when the transistor 30 is, for example, a P-type, by applying a voltage to the word line W1 so that the voltage of the gate terminal 31 with respect to the first terminal 33 or the second terminal 34 described later of the transistor 30 becomes negative, The plurality of transistors 30 connected to the word line W1 can be turned on simultaneously.

  In FIG. 1 and FIG. 2, dotted lines denoted by reference numerals B1 to Bn are provided to transmit a detection signal including information on the electrical resistance of the unit region 38e of the pressure-sensitive conductor 38 connected to each transistor 30. Represents a bit line. Each of the bit lines B1 to Bn is electrically connected to the first terminals 33 of the plurality of transistors 30 arranged along the second direction D2. For example, the bit line B1 is positioned on the leftmost side in the drawing of FIGS. 1 and 2 and is electrically connected to the first terminals 33 of the plurality of transistors 30 arranged along the second direction D2. In this case, the detection signal extracted from one transistor 30 which is turned on by the control signals from the word lines W1 to Wm among the plurality of transistors 30 connected to the bit line B1 is transmitted to the bit line B1. Communicated. As will be described later, in the sensor process for detecting pressure, the detection signal may be the current value of the first current flowing through the unit region 38e of the pressure-sensitive conductor 38.

  1 and 2, even if the number of word lines W1 to Wm and bit lines B1 to Bn is smaller than the number of transistors 30, the bit lines B1 to Bn and the word line W1. By arranging ~ Wm in a matrix, a detection signal from any transistor 30 can be taken out. For this reason, the number of lines provided on the substrate 21 can be reduced. As shown in FIGS. 1 and 2, the bit lines B1 to Bn and the word lines W1 to Wm are connected to corresponding terminal portions 24, respectively. The above-described cable 45 is also connected to the corresponding terminal portion 24.

  As long as the transistor 30 and the terminal portion 24 can be appropriately supported, the material constituting the base material 21 is not particularly limited. For example, the base material 21 may be a flexible substrate having flexibility or a rigid substrate having no flexibility.

  Next, the transistor 30 will be described in detail with reference to FIG. 4 is an enlarged cross-sectional view showing one of the plurality of transistors 30 of the sensor unit 20 shown in FIG.

  As shown in FIG. 4, the transistor 30 includes a gate terminal 31 provided on the base material 21, a gate insulating film 32 provided on the base material 21 so as to cover the gate terminal 31, and the gate insulating film 32. The semiconductor layer 35 provided, a first terminal 33 connected to one end of the semiconductor layer 35, and a second terminal 34 connected to the other end of the semiconductor layer 35 are included. One of the first terminal 33 and the second terminal 34 functions as a so-called source terminal and the other functions as a so-called drain terminal according to the voltage between the first terminal 33 and the second terminal 34. An insulating layer 36 is provided so as to cover the first terminal 33, the second terminal 34, and the semiconductor layer 35. A conductive first electrode 37 is provided on the insulating layer 36. The first electrode 37 is connected to the second terminal 34 through a through hole 36 a formed in a part of the insulating layer 36. Electrically connected. In the example shown in FIG. 4, a through hole 36a is formed on the second terminal 34, and the second terminal 34 and the first electrode 37 are electrically connected through the through hole 36a. The first electrode 37 is in contact with the first surface 38 a of the pressure-sensitive conductor 38 on the side opposite to the side where the second terminal 34 is located. The first electrode 37 may be filled in the entire area of the through hole 36a, or may be provided only on the wall surface of the through hole 36a.

  As materials constituting the gate terminal 31, the gate insulating film 32, the first terminal 33, the second terminal 34, and the insulating layer 36, known materials used in transistors are used. For example, the materials disclosed in JP 2010-79196 A can be used.

  As a material constituting the semiconductor layer 35, either an inorganic semiconductor material or an organic semiconductor material may be used, but an organic semiconductor material is preferably used. Organic semiconductor materials can generally be formed on a substrate at a lower temperature than inorganic semiconductor materials. For this reason, a material such as plastic having flexibility can be used as a material constituting the base material 21 that supports the transistor 30. This makes it possible to provide a lightweight transistor sheet that is stable against mechanical shock. Moreover, since an organic semiconductor material can be formed on the base material 21 using a coating process such as a printing method, a larger number of organic transistors can be efficiently formed on the base material 21 than when an inorganic semiconductor material is used. Can be formed. For this reason, there is a possibility that the manufacturing cost of the transistor sheet can be reduced.

  As the organic semiconductor material, a low molecular organic semiconductor material such as pentacene or a high molecular organic semiconductor material such as polypyrrole can be used. More specifically, a low molecular organic semiconductor material or a high molecular organic semiconductor material disclosed in JP2013-21190A can be used. Here, the “low molecular organic semiconductor material” means, for example, an organic semiconductor material having a molecular weight of less than 10,000. The “polymeric organic semiconductor material” means, for example, an organic semiconductor material having a molecular weight of 10,000 or more.

  As shown in FIGS. 3 and 4, a second electrode 39 having conductivity is provided on the second surface 38 b of the pressure-sensitive conductor 38. A coating layer 40 that covers the second electrode 39 may be provided on the second electrode 39. The covering layer 40 may function as a support for supporting the second electrode 39 before being stacked on the transistor 30 or the pressure-sensitive conductor 38. As a material constituting the coating layer 40, a resin material such as polyethylene terephthalate can be used.

  Similar to the pressure-sensitive conductor 38, the second electrode 39 and the base material layer 46 may be provided continuously across the plurality of transistors 30. In this case, the second electrode 39 and the base material layer 46 are commonly used in the plurality of transistors 30.

  As a material constituting the first electrode 37 and the second electrode 39, preferably, charged particles are efficiently injected into the pressure-sensitive conductor 38 containing rubber, or the efficiency is increased from the pressure-sensitive conductor 38 containing rubber. A material capable of taking out charged particles is used. As an example of such a material, for example, a conductive carbon material can be cited so as to be supported by examples described later. As the conductive carbon material, a material having a graphite structure or a similar structure, such as carbon black, can be used. As a result, charges are accumulated at the interface between the first surface 38 a of the pressure-sensitive conductor 38 and the first electrode 37 and at the interface between the second surface 38 b of the pressure-sensitive conductor 38 and the second electrode 39. It can be suppressed. This can reduce measurement errors that may occur when measuring the electrical resistance of the pressure-sensitive conductor 38, as will be described later.

  3 and 4 described above show an example in which the transistor 30 is a so-called bottom gate type. However, the type of the transistor 30 is not limited to the bottom gate type. For example, as shown in FIG. 5, the transistor 30 is a so-called top gate type in which the gate terminal 31 is disposed at a position farther from the base material 21 than the first terminal 33, the second terminal 34, and the semiconductor layer 35. Also good.

  FIG. 6 is a circuit diagram showing the transistor 30 and the pressure-sensitive conductor 38 of the sensor unit 20. In the following description, as shown in FIG. 6, the transistor 30 having the gate terminal 31 electrically connected to the word line Wi and the first terminal 33 electrically connected to the bit line Bj is referred to as transistor 30_ij. Also expressed. Further, the unit region 38e of the pressure-sensitive conductor 38 that is electrically connected to the second terminal 34 of the transistor 30_ij is also referred to as a unit region 38e_ij. Here, i is an arbitrary integer within the range of 1 to m, and j is an arbitrary integer within the range of 1 to n.

  FIG. 6 shows an example in which the second electrode 39 is connected to the ground potential. However, as long as the potential of the second electrode 39 is stable, the specific value of the potential of the second electrode 39 is There is no particular limitation. For example, the second electrode 39 may be connected to the power supply potential. Further, as described later as a modification, the potential of the second electrode 39 may be variable.

  Next, a control method of the pressure sensor device 10 having such a configuration will be described. First, the sensor process S10 for applying a voltage to the sensor unit 20 using the control unit 50 will be described so that information regarding the electrical resistance of the plurality of unit regions 38e of the pressure-sensitive conductor 38 can be obtained.

(Sensor processing)
In the sensor process S10, the control unit 50 applies a voltage to the word lines W1 to Wm so that the plurality of transistors 30 arranged in a matrix are sequentially turned on. For example, when the transistor 30 is P-type and the potential of the second terminal 34 is 0V, as shown in FIG. 7, a pulse having a negative first word potential V _1w is sequentially applied to the word lines W1 to Wm. . As a result, the voltage of the gate terminal 31 with respect to the second terminal 34 becomes negative in turn, and the transistor 30 is turned on in turn. Thus, in the sensor process S10, the second terminal 34 functions as a source terminal, and the first terminal 33 functions as a drain terminal.

The width of the pulse is appropriately determined according to the number of word lines and the period during which the sensor process S10 is performed. For example, when the number of word lines is 256 and the period during which the sensor process S10 is performed is 10 ms, the pulse width is set to about 37 μs. The value of the first word potential V _1w is appropriately determined according to the characteristics of the transistor 30. For example, the first word potential V _1w can be set to −20V. 7 and 8, the symbol V _OFF represents a potential applied to the word line when the transistor 30 is turned off.

During the sensor processing S10, as shown in FIG. 7, the potential of the bit line Bl to Bn, it is controlled to a negative first bitline potential _{V 1B} by the control unit 50. In this case, the current corresponding to the electric resistance of the unit region 38e is applied to the bit lines B1 to Bn, the on-state transistor 30, and the unit region 38e of the pressure-sensitive conductor 38 connected to the on-state transistor 30. The piezoelectric conductor 38 flows from the second surface 38b side toward the first surface 38a side. Here, the current and voltage from the second surface 38b side to the first surface 38a side of the pressure-sensitive conductor 38 are expressed as negative current and voltage. Therefore, on the contrary, the current and voltage from the first surface 38a side to the second surface 38b side of the pressure-sensitive conductor 38 are expressed as positive current and voltage. The first bit potential V _1B can be set to −20V, for example.

  FIG. 8 shows the potential of the word line Wi, the potential of the bit line Bj, and the second terminal 34 of the transistor 30_ij having the gate terminal 31 connected to the word line Wi and the first terminal 33 connected to the bit line Bj. It is a timing diagram which shows the voltage applied to unit area | region 38e_ij of the pressure sensitive conductor 38 connected to. FIG. 8 also shows the current flowing through the bit line Bj.

During the sensor processing S10, the pulse having a negative first wordline potential _{V 1 w} is applied to the word line Wi, the transistor 30_ij is turned on. As a result, as shown in FIG. 8, while the pulse having the negative first word potential V _1w is applied to the word line Wi, the unit region 38e_ij of the pressure sensitive conductor 38 connected to the transistor 30_ij has a negative polarity. first voltage _{E 1} is applied. In the bit line Bj, can almost ignore the load other than the unit area 38E_ij, and when the potential of the second electrode 39 is 0V, the negative first voltage _{E 1} that is applied to the unit area 38E_ij the first bit of the above It becomes almost equal to the potential V _1B .

A negative first current I _{1 (ij)} flows through the bit line Bj according to the negative first voltage E ₁ . Note that transistors 30_1j to 30_nj are connected to the bit line Bj, and the transistors 30_1j to 30_nj are sequentially turned on. Therefore, the current flowing through the bit line Bj during the sensor process S10 is not limited to the negative first current I1 _(ij) . As shown in FIG. 8, during the sensor process S10, the negative first current I _{1 (1j)} passing through the unit regions 38e_1j to 38e_nj of the transistors 30_1j to 30_nj and the corresponding pressure-sensitive conductor 38 is applied to the bit line Bj. ˜I _{1 (nj)} flows in order.

  The method for measuring the current flowing through the bit line Bj is not particularly limited, and a known method can be appropriately used. For example, the current flowing through the bit line Bj can be measured by inserting a shunt resistor having a known electric resistance into the bit line Bj and measuring the voltage across the terminals of the shunt resistor.

A negative first voltage _{E 1} applied to a unit area 38e_ij of the pressure-sensitive conductor 38, on the basis of the first current _{I 1} negative _(ij) flowing through the bit line Bj, the unit of the pressure-sensitive conductor 38 area The electrical resistance of 38e_ij can be calculated. The pressure applied to the unit region 38e_ij can be calculated based on the information related to the electrical resistance of the unit region 38e_ij. Thus, the pressure distribution of the external force F applied to the sensor unit 20 can be calculated by sequentially calculating the pressure applied to the plurality of unit regions 38e of the pressure-sensitive conductor 38.

  In the sensor process S10, as shown in FIG. 8, the direction of the voltage applied to the pressure-sensitive conductor 38 when a current flows through the pressure-sensitive conductor 38 is always negative. Accordingly, during the sensor process S10, a current flows through the pressure-sensitive conductor 38 only in the direction from the second surface 38b to the first surface 38a. That is, the direction of the current flowing through the pressure-sensitive conductor 38 during the sensor process S10 is only one direction. As a result of extensive research conducted by the inventors, in addition to the creep characteristics of the rubber described above, the direction of the current flowing through the pressure-sensitive conductor 38 is only in one direction, and the pressure applied to the pressure-sensitive conductor, It has been found that the relationship between the electrical resistance of the pressure sensitive conductor can change over time.

  The reason why the relationship between the pressure applied to the pressure-sensitive conductor and the electrical resistance of the pressure-sensitive conductor changes over time when the direction of the current flowing through the pressure-sensitive conductor 38 is only one direction is as follows: Although not particularly limited, for example, the following reasons can be considered.

  The first reason is that the interface between the first surface 38a of the pressure-sensitive conductor 38 and the first electrode 37 and the interface between the second surface 38b of the pressure-sensitive conductor 38 and the second electrode 39 are used. The effect of accumulated charge is considered. For example, it is assumed that the amount of accumulated charge changes with time, whereby the electric field generated based on the charge also changes with time. In this case, the relationship between the voltage applied to the pressure-sensitive conductor 38 and the current flowing through the bit line changes with time. As a result, the pressure applied to the pressure-sensitive conductor 38 and the pressure-sensitive conductor 38 are changed. It can be considered that the relationship between the electrical resistance and the electrical resistance also changes over time.

  The second reason is considered to be the influence of the charge accumulated at the interface between the portion where the plurality of conductive particles are in contact with each other and the surrounding rubber portion in the pressure-sensitive conductor 38. . In this case as well, as in the case of the first reason described above, the amount of accumulated charge changes with time, so that the pressure applied to the pressure-sensitive conductor and the electric resistance of the pressure-sensitive conductor are reduced. It can be assumed that the relationship changes over time.

  Against this background, in the present embodiment, it is proposed that the control unit 50 further performs the reset process S20 before or after the sensor process S10. Hereinafter, the reset process S20 will be described. Here, as shown in FIGS. 7 and 8, an example in which the reset process S20 is performed after the sensor process S10 will be described.

(Reset processing)
Reset process S20 is a process voltage applied to the pressure-sensitive conductor 38 and the first voltage E ₁ for applying a voltage to the sensor unit 20 so that the second voltage E ₂ of the opposite sense. For example, when the first voltage E ₁ is a negative voltage, the control unit 50 applies the positive second voltage E ₂ to the pressure-sensitive conductor 38 during the reset process S20 as shown in FIGS. Apply. Specifically, the second word potential V _2w of the word line becomes negative with respect to the second bit potential V _2B of the bit line in the reset process S20, and thereby the voltage of the gate terminal 31 with respect to the first terminal 33 becomes negative. As a result, the control unit 50 applies a voltage to the sensor unit 20 so that the transistor 30 is turned on. As a result, a positive second voltage E ₂ is applied to the pressure-sensitive conductor 38, and as a result, a positive second current flows through the pressure-sensitive conductor 38. Thus, in the reset process S20, the first terminal 33 connected to the bit line functions as a source terminal, and the second terminal 34 functions as a drain terminal. Period t the second voltage _{E 2} positive in pressure-sensitive conductor 38 is applied is set to, for example, 100 [mu] s. The period considering terms to eliminate the bias in electrical state of the unit region 38e of the pressure-sensitive conductor 38, a second voltage of the positive to the unit of the pressure-sensitive conductor 38 regions 38e E ₂ is applied t preferably, the first voltage E ₁ of the negative to the unit area 38e of the pressure-sensitive conductor 38 is of the same order as the period to be applied. On the other hand, when applying a simultaneous positive second voltage to the plurality of unit regions 38e E _2, the period for applying the second voltage E ₂ positive in the unit area 38e, a first voltage E ₁ of the negative to the unit area 38e If the period is approximately the same as the application period, the transistor 30 is not sufficiently turned on due to an increase in current capacity and load caused by applying a voltage to the plurality of unit regions 38e, and thus the plurality of unit regions 38e. There is a possibility that a sufficiently positive voltage cannot be applied. In this case, the period for applying a positive second voltage E ₂ to the unit area 38e is a longer period than the application of a first voltage E ₁ of the negative to the unit area 38e, and electrically unit area 38e It is preferable that the minimum period that can eliminate the unevenness of the state is set.
After the reset process S20 is performed, the sensor process S10 is performed again as shown in FIGS.

In FIG. 7 and 8, after implementing the sensor processing S10, after the elapse of a certain time, but examples of applying a positive second voltage E ₂ to sensitive conductor 38 is shown, It is not limited to this. For example, although not shown, immediately after implementing the sensor processing S10, a positive second voltage E ₂ may be applied to the pressure-sensitive conductor 38. 7 and FIG. 8, an example in which the sensor process S <b> 10 is performed again after a certain time has elapsed after the positive second voltage E <b> ₂ is applied to the pressure-sensitive conductor 38 for a predetermined period. Is shown, but is not limited to this. For example, although not shown, immediately after the application of a second voltage E ₂ positive with respect to the pressure-sensitive conductor 38 for a predetermined period of time, it may be performed again sensor processing S10.

The value of the second word potential V _2w of the word line in the reset process S20 is set so that the corresponding transistor 30 is turned on when the second bit potential V _2B is applied to the bit line. Yes. For example, as shown in FIGS. 7 and 8, when the positive second bit potential V _2B is applied to the bit line during the reset process S20, the second word potential V _2w of the word line can be set to 0V.

In FIG. 7 and 8, during the reset process S20, the control unit 50 is an example of always applying a second wordline potential _{V 2w} is shown in all the word lines W1 to Wm. In this case, the voltage applied to the plurality of unit areas 38e of the pressure-sensitive conductor 38 at the same time, the second voltage E ₂ of the direction opposite to the first voltage E _1. As a result, for example, the positive second current I2 _(j) flowing through the bit line Bj is converted into the plurality of transistors 30_1j to 30_nj connected to the bit line Bj and the corresponding pressure-sensitive conductor 38, as shown in FIG. Is the sum of currents passing through the unit regions 38e_1j to 38e_nj.

According to the present embodiment, by performing the reset process S20 described above, the second voltage E _{2 in} the direction opposite to the first voltage E ₁ applied to the pressure-sensitive conductor 38 during the sensor process S10. Can be applied to the pressure sensitive conductor 38. For this reason, compared with the case where such reset process S20 is not implemented, it can suppress that a biased electrical state of the pressure-sensitive conductor 38 occurs. For example, at the interface between the first surface 38 a and the first electrode 37 of the pressure-sensitive conductor 38, the interface between the second surface 38 b and the second electrode 39, or the interface that can be formed inside the pressure-sensitive conductor 38. Accumulation of charges can be suppressed. Thereby, it is possible to suppress the relationship between the pressure applied to the pressure-sensitive conductor 38 and the electric resistance of the pressure-sensitive conductor 38 from changing with time. For this reason, according to this Embodiment, it can suppress that the precision of the pressure measured by the pressure sensor apparatus 10 deteriorates with progress of time, employing a simple structure and data analysis.

  Note that various modifications can be made to the above-described embodiment. Hereinafter, modified examples will be described with reference to the drawings as necessary. In the following description and the drawings used in the following description, the same reference numerals as those used for the corresponding parts in the above embodiment are used for the parts that can be configured in the same manner as in the above embodiment. A duplicate description is omitted. In addition, when it is clear that the operational effects obtained in the above-described embodiment can be obtained in the modified example, the description thereof may be omitted.

(First modification)
7 and 8 described above, during the reset process S20, the control unit 50, at the same time the voltage applied to the plurality of unit areas 38e of the pressure-sensitive conductor 38, the direction opposite to the first voltage E ₁ the second voltage E ₂ to become like, an example of applying a voltage to the sensor unit 20. However, it is not limited thereto, during the reset process S20, the control unit 50 in turn is a voltage applied to the plurality of unit areas 38e of the pressure-sensitive conductor 38, the direction opposite to the first voltage E ₁ the second voltage E ₂ to become like, voltage may be applied to the sensor section 20. For example, the control unit 50 outputs a pulse having the second word potential V _2w for turning on the transistor 30 while the second bit potential V _2B is applied to the bit lines _{B 1} to Bn. You may apply to Wm in order. In this case, the unit area 38e of the pressure-sensitive conductor 38 connected to the transistor 30 connected to the word lines W1 to Wm, are sequentially positive second voltage E ₂ is applied, so that the order flow positive second current become. Therefore, for example, positive current passing through the plurality of transistors 30_1j to 30_nj connected to the bit line Bj and the corresponding unit regions 38e_1j to 38e_nj of the corresponding pressure sensitive conductor 38 flows in the bit line Bj in order. Therefore, according to this modification, the maximum value of the current flowing through each bit line during the reset process S20 can be reduced as compared with the case of the above-described embodiment. Therefore, the current capacity that should be prepared by the control unit 50 for each bit line can be reduced.

  On the other hand, in the above-described embodiment, for example, a positive current can be simultaneously supplied to the plurality of transistors 30_1j to 30_nj connected to the bit line Bj and the corresponding unit regions 38e_1j to 38e_nj of the pressure-sensitive conductor 38. . That is, the process for eliminating the bias in the electrical state of the pressure-sensitive conductor 38 can be simultaneously performed on the plurality of unit regions 38e. For this reason, according to the above-described present embodiment, the time required for flowing a positive current to all the plurality of unit regions 38e in the reset process S20 is shortened compared to the case of the above-described first modification. Can do.

Hereinafter, the control unit 50, during the reset process S20, so that the second voltage E ₂ of the direction opposite to the voltage in turn first voltage E ₁ that is applied to the plurality of unit areas 38e of the pressure-sensitive conductor 38 An example of applying a voltage to the sensor unit 20 will be described with reference to FIGS. 13 and 14. In this modification, the potential of the second electrode 39 is variable. For example, the control unit 50 controls the potential of the second electrode 39 in addition to the word lines W1 to Wm and the bit lines B1 to Bn.

First, the sensor process S10 in this modification will be described. In the sensor process S10, as in the case of the above-described embodiment, as illustrated in FIG. 7, the control unit 50 sequentially applies a pulse having the negative first word potential V _1w to the word lines W1 to Wm. To do. The control unit 50 controls the potential of the bit line B1~Bn the first bitline potential _{V 1B,} controls the potential of the second electrode 39 to the first common potential _{V 1C.} The first word potential V _1w , the first bit potential V _1B , and the first common potential V _1C are set so that the transistor 30 to which a pulse having the first word potential V _1w is applied is turned on. For example, the first word potential V _1w is −20V, the first bit potential V _1B is −10V, and the first common potential V _1C is 0V.

In the sensor process S10, in the transistor 30 to which the pulse having the first word potential V _1w is applied, the voltage of the gate terminal 31 with respect to the second terminal 34 connected to the second electrode 39 via the pressure-sensitive conductor 38. Becomes negative, and the transistor 30 is turned on. Thus, in the sensor process S10, the second terminal 34 functions as a source terminal, and the first terminal 33 functions as a drain terminal. In the sensor processing S10, the unit region 38e of the pressure-sensitive conductor 38 connected to the transistor 30 in the ON state, as shown in FIG. 14, a first negative voltage E ₁ is applied.

Next, the reset process S20 in this modification will be described. In the reset process S20, the control unit 50, as shown in FIG. 13, it is sequentially applied to a pulse having a negative second wordline potential _{V 2w} to the word lines W1 to Wm. The control unit 50 controls the potential of the bit line B1~Bn the first bitline potential _{V 2B,} controls the potential of the second electrode 39 to the second common potential _{V 2C.} The second word potential V _2w , the second bit potential V _2B , and the second common potential V _2C are turned on when the transistor 30 to which a pulse having the second word potential V _2w is applied is turned on. 30 is set such that a current in the direction opposite to that in the sensor process S10 flows. For example, the second word potential V _2w is −20V, the first bit potential V _1B is −10V, and the first common potential V _1C is −20V.

In the reset process S20, the transistor 30 is applied with pulses having a second wordline potential _{V 2w,} the voltage of the gate terminal 31 to the first terminal 33 connected to the bit line B1~Bn is negative, transistor 30 Turns on. As described above, in the reset process S20, the first terminal 33 functions as a source terminal, and the second terminal 34 functions as a drain terminal. In the reset process S20, the unit region 38e of the pressure-sensitive conductor 38 connected to the transistor 30 in the ON state, as shown in FIG. 14, a positive second voltage E ₂ is applied. In this way, by applying the second voltage E ₂ in the opposite direction to the first voltage E ₁ applied to the pressure-sensitive conductor 38 during the sensor process S 10 to the pressure-sensitive conductor 38, the pressure-sensitive conduction is performed. It is possible to suppress the occurrence of bias in the electrical state of the body 38.

In the reset process S20 in this modified example, the unit area 38e of the pressure-sensitive conductor 38 connected to the transistor 30 connected to the word lines W1 to Wm, are sequentially positive second voltage E ₂ is applied, in turn positive The second current flows. Therefore, as shown in FIG. 14, for example, the bit line Bj includes a positive current passing through the plurality of transistors 30_1j to 30_nj connected to the bit line Bj and the corresponding unit regions 38e_1j to 38e_nj of the pressure-sensitive conductor 38. Flows in order. For this reason, according to the present modification, the maximum value of the current flowing through each bit line during the reset process S20 can be reduced as compared with the case of the above-described embodiment. Therefore, the current capacity that should be prepared by the control unit 50 for each bit line can be reduced. FIG. 14 shows a state in which a substantially constant current continuously flows in the bit line Bj as a result of the positive current passing through the plurality of transistors 30_1j to 30_nj sequentially flowing in the bit line Bj during the reset process S20. Has been.

Incidentally, in the modified example described above, the example of applying a pulse having a negative second wordline potential V _2w to one of a plurality of word lines W1~Wm sequentially, is not limited thereto. For example, a pulse having a negative second word potential _V2w may be applied simultaneously to a plurality of word lines. Specifically, first, a pulse having a negative second word potential _V2w is simultaneously applied to the word line W1 and the word line W2, and then a negative second word potential V is simultaneously applied to the word line W3 and the word line W4. A pulse having _2w may be applied. In this case, the reset process for the unit region 38e of the pressure-sensitive conductor 38 is performed using the unit regions 38e of the pressure-sensitive conductor 38 connected to the transistor 30 controlled by the two word lines W as one unit. It is carried out in order. As described above, the number of unit regions 38e on which the reset process is simultaneously performed among the plurality of unit regions 38e of the pressure-sensitive conductor 38 is arbitrary.

(Second modification)
In the above-described embodiment, an example in which the electrical resistance of the plurality of unit regions 38e of the pressure-sensitive conductor 38 is individually measured using at least one transistor 30 provided for one unit region 38e. showed that. That is, an example in which a so-called active matrix method is employed has been shown. However, the present invention is not limited to this, and a so-called passive matrix method may be employed as a method of individually measuring the electric resistances of the plurality of unit regions 38e of the pressure-sensitive conductor 38.

(Third Modification)
In the above-described embodiment, an example in which the pressure-sensitive conductor 38 is partitioned into the plurality of unit regions 38e has been described, but the present invention is not limited to this. For example, only one transistor 30 may be connected to the entire pressure sensitive conductor 38. Even in this case, it is possible to suppress the occurrence of bias in the electrical state of the pressure-sensitive conductor 38 by performing the reset process S20 described above.

(Other variations)
In the above-described embodiment, the example in which the control unit 50 that controls the sensor unit 20 is electrically connected to the sensor unit 20 via the cable 45 has been described. However, the place where the control unit 50 is provided is not particularly limited. For example, the control unit 50 may be provided on the base material 21 of the sensor unit 20 like the transistor 30 and the like of the sensor unit 20.

  In the above-described embodiment, the example in which the first electrode 37 is in contact with the pressure-sensitive conductor 38 has been described. However, the present invention is not limited to this, and as shown in FIG. 11, the first electrode 37, the pressure-sensitive conductor 38, and the like sandwiching an opening such as a through hole 36 a formed in a part of the insulating layer 36. May be opposed to each other. In this case, it is ensured that the first electrode 37 and the pressure-sensitive conductor 38 are not in contact with each other when no pressure is applied to the transistor 30. For this reason, in a state where no pressure is applied to the transistor 30, it is possible to suppress the deviation of the electrical state of the pressure-sensitive conductor 38 and the generation of noise. In this case, a part of the pressure-sensitive conductor 38 pushed into the through hole 36 a is not first applied to the pressure-sensitive conductor 38 in the thickness direction of the pressure-sensitive conductor 38. Come into contact with. That is, the second terminal 34 is electrically connected to the pressure-sensitive conductor 38 when pressure is applied to the pressure-sensitive conductor 38. For this reason, the pressure of the pressure-sensitive conductor 38 pressed against the first electrode 37 can be reduced as compared with the conventional case. Thereby, even when a large pressure is applied to the pressure-sensitive conductor 38, it is possible to suppress an excessive current from flowing to the first electrode 37 and the pressure-sensitive conductor 38. In this respect as well, it is possible to suppress the deviation of the electrical state of the pressure-sensitive conductor 38. Further, increase in power consumption of the transistor 30 and power consumption of an external driving circuit for driving the transistor 30 can be suppressed. In addition, it is possible to suppress an excessive load from being applied to an external drive circuit for driving the transistor 30.

  FIG. 11 shows an example in which the first electrode 37 connected to the second terminal 34 is opposed to the pressure-sensitive conductor 38 with the opening interposed therebetween. However, although not shown, the second terminal 34 may face the pressure-sensitive conductor 38 with the opening interposed therebetween.

  In FIG. 11, in the bottom gate type transistor 30, the first electrode 37 and the pressure-sensitive conductor 38 face each other with an opening such as a through hole 36 a formed in a part of the insulating layer 36 therebetween. An example configured as shown above was shown. However, the present invention is not limited to this, and as shown in FIG. 12, the first electrode 37 and the pressure-sensitive conductor 38 are sandwiched between openings such as through holes 36a formed in a part of the insulating layer 36. And the gate terminal 31 may be disposed at a position farther from the base material 21 than the first terminal 33, the second terminal 34, and the semiconductor layer 35. That is, the opposing structure of the first electrode 37 and the pressure-sensitive conductor 38 shown in FIG. 11 may be applied to the top-gate transistor 30.

  In addition, although some modified examples with respect to the above-described embodiment have been described, naturally, a plurality of modified examples can be applied in combination as appropriate.

  Next, the embodiment of the present disclosure will be described more specifically by way of examples. However, the embodiment of the present disclosure is not limited to the description of the following examples unless it exceeds the gist.

Example 1
First, a first electrode 37 containing a conductive carbon material is attached to the first surface 38a of the pressure-sensitive conductor 38, and a second electrode 39 containing a conductive carbon material is attached to the second surface 38b of the pressure-sensitive conductor 38, A sensor body including the first electrode 37, the pressure-sensitive conductor 38 and the second electrode 39 was produced. Next, a pressure of 5 N / cm ² was periodically applied to the sensor body in a state where a voltage of +20 V was applied between the first electrode 37 and the second electrode 39. The period for applying pressure to the sensor body was approximately 20 s. Further, the current flowing through the sensor body was measured while the pressure was periodically applied to the sensor body. The results are shown in FIG.

(Example 2)
Example 1 except that the first electrode 37 containing aluminum and the second electrode 39 containing aluminum were used, and the voltage applied between the first electrode 37 and the second electrode 39 was −20V. Similarly, the current flowing through the sensor body was measured. The results are shown in FIG.

  As shown in FIG. 10, when the first electrode 37 and the second electrode 39 contain aluminum, the value of the current flowing through the sensor body when pressure was applied changed with time. On the other hand, when the first electrode 37 and the second electrode 39 include a conductive carbon material, the value of the current that flows through the sensor body when pressure is applied hardly changed even after time had elapsed. It can be said that it is advantageous to use a conductive carbon material for the first electrode 37 and the second electrode 39 in order to suppress a change in electrical characteristics of the pressure-sensitive conductor 38.

DESCRIPTION OF SYMBOLS 10 Pressure sensor apparatus 20 Sensor part 21 Base material 24 Terminal part 30 Transistor 31 Gate terminal 32 Gate insulating film 33 1st terminal 34 2nd terminal 35 Semiconductor layer 36 Insulating layer 37 1st electrode 38 Pressure sensitive conductor 39 2nd electrode 40 Cover layer 55 Cable 60 Controller

Claims (8)

A pressure sensor device,
A sensor unit having a pressure sensitive conductor configured to change electrical resistance in response to applied pressure;
A first unit for applying a voltage to the sensor unit so as to obtain information on the electrical resistance of the pressure-sensitive conductor, and a control unit for performing a second process for applying a voltage to the sensor unit,
The pressure sensitive conductor is partitioned into a plurality of unit regions,
The sensor unit and the control unit are configured to respectively obtain information on the electrical resistance of the plurality of unit regions of the pressure-sensitive conductor,
During the first process, the control unit applies a voltage to the sensor unit such that a voltage applied to the plurality of unit regions of the pressure-sensitive conductor becomes a first voltage,
In the second process, the control unit is configured to control the sensor unit so that a voltage applied to the plurality of unit regions of the pressure-sensitive conductor is a second voltage in a direction opposite to the first voltage. Pressure sensor device that applies voltage to The pressure sensor device according to claim 1, wherein the plurality of unit regions are connected to a common electrode at a ground potential or a power supply potential . The sensor unit includes a plurality of transistors each of the unit areas being electrically connected to corresponding one of the pressure-sensitive conductive material, the pressure sensor device according to claim 1 or 2. During the second process, the control unit is configured so that the voltage applied to the plurality of unit regions of the pressure-sensitive conductor simultaneously becomes a second voltage in a direction opposite to the first voltage. a voltage is applied to the part, a pressure sensor device according to any one of claims 1 to 3. In the second process, the control unit is configured so that the voltage applied to the plurality of unit regions of the pressure-sensitive conductor sequentially becomes a second voltage in a direction opposite to the first voltage. a voltage is applied to the part, a pressure sensor device according to any one of claims 1 to 3. The sensor unit includes a first electrode and a second electrode that are in contact with the pressure-sensitive conductor,
6. The pressure sensor device according to claim 1, wherein at least one of the first electrode and the second electrode includes a conductive carbon material. A pressure sensor method for detecting pressure applied to a pressure-sensitive conductor divided into a plurality of unit regions ,
Based on the electrical resistance of the plurality of unit regions of the pressure-sensitive conductor when a first voltage is applied to the plurality of unit regions of the pressure-sensitive conductor, the plurality of unit regions of the pressure-sensitive conductor are applied to the unit regions . A first treatment step for calculating each applied pressure;
And a second processing step of applying a second voltage in a direction opposite to the first voltage to the plurality of unit regions of the pressure-sensitive conductor. A non-transitory computer-readable storage medium storing a program for executing a pressure sensor method for detecting a pressure applied to a pressure-sensitive conductor divided into a plurality of unit regions ,
The pressure sensor method includes:
Based on the electrical resistance of the plurality of unit regions of the pressure-sensitive conductor when a first voltage is applied to the plurality of unit regions of the pressure-sensitive conductor, the plurality of unit regions of the pressure-sensitive conductor are applied to the unit regions . A first treatment step for calculating each applied pressure;
And a second processing step of applying a second voltage in a direction opposite to the first voltage to the plurality of unit regions of the pressure-sensitive conductor.

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