Electrostatic Sensor and Electrostatic Sensor System

Abstract

To solve the problem of a conventional method in which chargeable powders containing a coloring agent are caused to adhere to an object so that the charge distribution can be confirmed as a charging pattern, but the chargeable powders are difficult to handle because they scatter around the object when they are caused to adhere thereto and the chargeable powders have to be removed.SOLUTION: An electrostatic sensor includes an array of extension gates and a plurality of field-effect transistors. Each of the extension gates is electrically connected to a gate electrode of the field-effect transistor.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an electrostatic sensor and an electrostatic sensor system for measuring static electricity generated on the surface of an object.

Background Art

[0002] When using a non-conductive material, problems may occur due to surface charging. For example, when painting a plastic member, uneven charging distribution may cause uneven painting. Also, in the semiconductor manufacturing process, it is important to remove charging. For these reasons, the static electricity on the surface of the object is measured. Also, by measuring static electricity, it can be used as a proximity sensor or a contact sensor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Patent Document 1 describes a method of attaching a charged powder containing a colorant to an object so that the charge distribution can be confirmed as a charge pattern. However, this method was difficult to handle because the charged powder scattered around during attachment and had to be removed.

Means for Solving the Problems

[0005] One embodiment of the present invention provides an electrostatic sensor including a plurality of arranged extending gates and a plurality of field effect transistors, each of the extending gates being electrically connected to the gate electrode of the field effect transistor.

Effects of the Invention

[0006] According to an embodiment of the present invention, charging by static electricity can be detected with high sensitivity without using charged powder. Further, by using it as an input for a proximity sensor, operations can be performed hygienically without using buttons or touch panels that are touched by an unspecified number of people.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Modes for Carrying Out the Invention

[0008] First, the principle of the electrostatic sensor of this embodiment will be described with reference to FIG. 1. FIG. 1 shows a cross-sectional view and a circuit of the electrostatic sensor. The electrostatic sensor includes a field-effect transistor 1 and an extended gate 3. The field-effect transistor 1 has a semiconductor 11, a gate electrode 12, a first insulating layer 13, a source electrode 14, and a drain electrode 15. The gate electrode 12 is sandwiched from the Z direction by the second insulating layer 2 and the first insulating layer 13. Also, the extended gate 3 electrically connected to the gate electrode 12 is also sandwiched between the second insulating layer 2 and the first insulating layer 13. The extended gate 3 extends over a wider range than the gate electrode 12 at least in the X direction, which is the extending direction. In FIG. 1, the gate electrode 12 is connected to the extended gate 3 by a connection line 31. The source electrode 14 of the electrostatic sensor is connected to a current detector 6 via a detection line 61, and the drain electrode 15 is connected to the negative electrode of a power source 4 via a voltage line 41. Then, the positive electrode of the power source 4 and the current detector 6 are connected to the ground 5.

[0009] The gate electrode 12, the connection line 31, and the extended gate 3 are sandwiched between the first insulating layer 13 and the second insulating layer 2 and are electrically insulated from the outside. When an object 7 charged with static electricity as shown in FIG. 1 approaches the extended gate 3 of the electrostatic sensor, due to the action of the electric field, electrons in the extended gate 3 are repelled and + charges are accumulated. Conversely, electrons in the gate electrode 12 increase and - charges are accumulated. Then, due to the - charges in the gate electrode 12, + charges are accumulated in the semiconductor 11, the resistance value of the field-effect transistor 1 decreases, and the current increases. The current is detected by the current detector 6. Thereby, it is possible to detect the charging of the object 7 and the approach of the object 7. In FIG. 1, although the gate electrode 12 is connected to the extended gate 3 by the connection line 31, the connection line 31 can also be considered as a part of the extended gate 3.

[0010] The semiconductor 11 changes its resistance value according to the change in the electric field. Therefore, without the extended gate 3 and the gate electrode 12, the semiconductor 11 can directly capture the electric field to serve as an electrostatic sensor. However, it has been experimentally found that the electrostatic sensor provided with the extended gate 3 and the gate electrode 12 shown in FIG. 1 has a sensitivity to capture the electric field that is more than 100 times higher than that of the electrostatic sensor without the extended gate 3 and the gate electrode 12.

[0011] In FIG. 1, the object 7 is separated from the electrostatic sensor. However, if the surface layer of the electrostatic sensor is formed of a non-conductive material that is less likely to be charged electrostatically, it can also be used in a mode where the object 7 is in contact with the surface of the electrostatic sensor.

Example

[0012] As Example 1, an electrostatic sensor system of a two-dimensional electrostatic sensor in which sensors are arranged two-dimensionally is shown. In FIG. 2, a 3×3 electrostatic sensor is shown, but generally, it can be an n×m (n and m are natural numbers) sensor. In the electrostatic sensor of FIG. 2, a plurality of voltage lines 41 extend in the row direction (X direction), and a plurality of detection lines 61 extend in the column direction (Y direction). The detection lines 61 and the voltage lines 41 are insulated from each other by an insulating layer in the Z direction. And in the X-Y plane, a P-type field-effect transistor 1 is provided near the intersection of the detection line 61 and the voltage line 41. For the field-effect transistor 1, the drain electrode 15 is electrically connected to the voltage line 41, the source electrode 14 is electrically connected to the detection line 61, and the gate electrode 12 is electrically connected to the extended gate 3. The detection line 61 is a source wiring, and the voltage line 41 is a drain wiring. A plurality of source electrodes 14 of the field-effect transistor 1 are connected to each of the detection lines 61 that are source wirings, and a plurality of drain electrodes 15 of the field-effect transistor 1 are connected to each of the voltage lines 41 that are drain wirings. In this embodiment, the detection line 61 and the voltage line 41 extend in the Y direction and the X direction, but they do not have to be perpendicular to each other as long as they extend in one direction and the other direction. This is the same for other embodiments of two-dimensional electrostatic sensors. Also, the voltage line 41 of the electrostatic sensor is connected to the power supply 4, and the detection line 61 is connected to the ground 5 via the current detector 6. In the current detector 6, a resistor (not shown) is provided between the detection line 61 and the ground 5, and the current is detected by measuring the voltage across both ends of the resistor. The electrostatic sensor system includes an electrostatic sensor, a power supply 4, and a current detector 6.

[0013] When detecting static electricity, a selection potential is sequentially supplied from the power supply 4 to a plurality of voltage lines 41. In FIG. 2, basically, a non-selection potential of 0 V is applied to the voltage lines 41, and a voltage of -5 V, which is the selection potential, is sequentially applied in the -Y direction. The P-type field effect transistor 1 connected to the voltage line 41 to which the -5 V voltage is applied has a lower resistance as the gate becomes negative, and a larger source current flows. Then, the source current flows through the detection line 61 and is detected by the current detector 6. In the sensor of the first embodiment, since the selection potential of -5 V is scanned and applied to the voltage lines 41 and detected by each current detector 6, the static electricity in the vicinity can be detected for each of the extended gates 3 arranged two-dimensionally.

[0014] Here, since there are parasitic capacitances between the gate-drain and the gate-source, when there is no object 7, the potential of the gate electrode 12 is between the potential of the drain electrode 15 and the potential of the source electrode 14. The resistance value of the resistance of the current detector 6 is small, and the potential of the detection line 61 and the source electrode 14 is approximately 0 V. When the potential of the voltage line 41 and the drain electrode 15 changes from 0 V to -5 V, the gate potential becomes approximately -2.5 V, which is the middle between the drain electrode 15 and the source electrode 14, and a bias is applied to the gate potential. Therefore, when no static electricity is nearby, the Vgs of the P-type field effect transistor 1 becomes approximately -2.5 V and a current flows. Then, even if the potential of the gate electrode 12 changes to the + side or the - side due to the electron transfer between the extended gate 3 when the object 7 approaches, the current of the P-type field effect transistor 1 changes and can be detected.

[0015] Incidentally, the detection output by the current detector 6 is preferably integrated for a period of the reciprocal of the power supply frequency (commercial frequency). FIG. 3 shows the output of the current detector 6. t is the time axis and I is the detected current. In a general use environment of the electrostatic sensor, an electric field of the commercial frequency by the commercial power supply may affect the potentials of the extending gate 3, the gate electrode 12, the semiconductor 11, etc. In FIG. 3, a signal Sn in which power supply noise is superimposed on the original signal S is shown. The power supply noise repeats with a period of 1 / Fc which is the reciprocal time of the power supply frequency Fc. Therefore, by integrating the signal Sn for a period of 1 / Fc, the power supply noise can be reduced and the value can be made closer to the value of the original signal S.

[0016] FIG. 4 shows the structure of the electrostatic sensor of Example 1. FIG. 4(a) is a partial plan view of one element in the electrostatic sensor, and FIG. 4(b) is a partial cross-sectional view on the extension line of the A-A line in FIG. 4(a). As shown in FIG. 4, in the electrostatic sensor of Example 1, an extending gate 3, a connection line 31, a gate electrode 12, and a detection line 61 are provided on the Z-facing surface of the second insulating layer 2 and further covered with the first insulating layer 13. On the Z-facing side of the first insulating layer 13, a semiconductor 11 is provided overlapping the position of the gate electrode 12, and a source electrode 14 and a drain electrode 15 are in contact with the semiconductor 11 and a voltage line 41 is provided. The source electrode 14 is connected to the detection line 61 through a through hole 62 provided in the first insulating layer 13. The detection line 61 extends in the Y direction on the Z-facing side of the second insulating layer 2 and is electrically connected to a current detector 6 outside the electrostatic sensor. Also, the drain electrode 15 extends in the X direction on the Z-facing side of the first insulating layer 13 and is electrically connected to a power supply 4 outside the electrostatic sensor. The intersection of the voltage line 41 extending in the X direction and the detection line 61 extending in the Y direction is insulated by the first insulating layer 13.

[0017] The extending gate 3 extends over a wider range than the gate electrode 12 in the X and Y directions. Therefore, charges can be efficiently collected at the gate electrode 12. Also, in this embodiment, the semiconductor 11 is a P-type organic semiconductor, and the field effect transistor 1 is a P-type organic field effect transistor (OFET). The insulating layer has flexibility, and the electrostatic sensor as a whole has flexibility.

Example

[0018] When the area of the extended gate 3 is small with respect to the object 7 and the distance from the adjacent extended gate 3 is large, as shown in Fig. 5(a), it is also affected by the electrostatic force around in the X-Y plane direction at the opposing positions. Therefore, high resolution cannot be obtained. Thus, in the second embodiment, as shown in Fig. 5(b), a conductive film 51 is provided around the semiconductor 11, and the conductive film 51 is fixed at a constant potential such as the ground 5. Thereby, the influence of the electrostatic force around in the X-Y plane direction at the opposing positions is suppressed, and high resolution can be obtained. Also, this technique can be used even when the semiconductor directly senses the electric field and changes its resistance in a field effect transistor without the gate electrode 12. In this case, the position of the extended gate 3 in Fig. 5(b) becomes a P-type semiconductor, and a conductive film 51 is formed around the semiconductor. Then, the conductive film 51 is fixed at a constant potential such as the ground 5.

Example

[0019] In Example 3, a mesh-shaped conductor is used for the extending gate 3. FIG. 6 shows the electrostatic sensor of Example 3 having a 2×2 sensor. Different from Example 1 shown in FIGS. 1 and 4, in FIG. 6 of Example 3, for the electrostatic sensor, a plurality of voltage lines 41 extend in the column direction (Y direction), and a plurality of detection lines 61 extend in the row direction (X direction). Also, the extending gate 3 is a mesh-shaped conductor 32 with a mesh-shaped conductor. The mesh-shaped conductor 32 is electrically connected to the gate electrode 12 of the field effect transistor 1 via the connection line 31. The gate electrode 12, source electrode 14, and drain electrode 15 are linear conductors and are not shown in FIG. 6. A first insulating layer 13 is provided between the source electrode 14 and the drain electrode 15 in the Z direction of the gate electrode 12. Also, the gate electrode 12, connection line 31, and mesh-shaped conductor 32 are sandwiched between the first insulating layer 13 and the second insulating layer 2. These points are the same as in Example 1. On the other hand, the gate electrode 12, source electrode 14, and drain electrode 15 extend in the X direction together with the detection line 61 such that the gate electrode 12 is sandwiched in the Y direction by the source electrode 14 and the drain electrode 15. Although not described in FIG. 6, a semiconductor 11 is provided between the source electrode 14 and the drain electrode 15 in the Y direction. Then, as shown in FIG. 6, a connection line 31 is further provided to extend in the extending direction of the gate electrode 12, and an extending gate 3 is provided on the opposite side of the gate electrode 12 in the connection line 31.

[0020] The mesh-shaped conductor 32, which is the extending gate 3, extends over a wider range than the gate electrode 12 in the X and Y directions. Therefore, charges can be efficiently collected on the gate electrode 12. Further, the connection line 31 extends in one direction from the mesh-shaped conductor 32, and the gate electrode 12 is formed by further extending in one direction from the connection line 31. Therefore, the gate electrode 12 is provided at a position away from the mesh-shaped conductor 32, and charges can be efficiently collected.

[0021] In this embodiment, the semiconductor 11 is a P-type organic semiconductor, and the field-effect transistor 1 is a P-type organic field-effect transistor (OFET). Also, the insulating layer sandwiching the field-effect transistor 1, the connection line 31, and the mesh-shaped conductor 32 has flexibility, and the electrostatic sensor as a whole has flexibility. The extending gate 3 has high flexibility because it is the mesh-shaped conductor 32 in a mesh shape. Further, since the first insulating layer 13 and the second insulating layer 2 sandwiching the mesh-shaped conductor 32 are joined in the Z direction within the mesh, peeling is less likely to occur even when the electrostatic sensor is repeatedly bent.

[0022] Also, if the first insulating layer 13 and the second insulating layer 2 are made transparent, even if the mesh-shaped conductor 32 is made of metal, the electrostatic sensor can be made substantially transparent. If the mesh-shaped conductor 32 is made of a transparent conductor, the transparency can be further increased. Further, the semiconductor 11 may be made of an inorganic semiconductor, or the insulating layer may not have flexibility, so that the electrostatic sensor as a whole does not have flexibility, and in this case, it can also be made substantially transparent.

[0023] The mesh-shaped extending gate 3 is not limited to the shape of the mesh-shaped conductor 32 in FIG. 6, and it is sufficient that there is a space without a conductor in the region of the extending gate 3. For example, a shape in which the conductor extends radially from a single point may be used, or a mesh shape such as a shape in which a plurality of vertical bars of conductors are joined to horizontal bars of one or more conductors, or a shape in which a plurality of holes are formed in a conductor plate may be used.

Embodiment

[0024] Example 4 is a one-dimensional electrostatic sensor with sensors arranged in a one-dimensional manner. Figure 7 shows a one-dimensional electrostatic sensor having seven sensors. The seven sensors are arranged and provided in the X direction, and a plurality of field effect transistors 1 are also arranged in the X direction. The extending gate 3 is also arranged in the X direction. Each of the gate electrode 12, source electrode 14, and drain electrode 15 of the field effect transistor 1 extends in the Y direction. Note that the extending direction of the field effect transistor 1 does not have to be perpendicular to the arrangement direction of the extending gate 3 as long as it intersects the arrangement direction of the extending gate 3. Although not shown in Figure 7, a P-type semiconductor 11 is provided between the source electrode 14 and the drain electrode 15 in the X direction. And, an extending gate 3 is provided in the -Y direction of the gate electrode 12, and the gate electrode 12 and the extending gate 3 are electrically connected by a connection line 31 extending in the Y direction. A voltage line 41 extending in the X direction is provided at the position of the field effect transistor 1 in the Y direction and is electrically connected to a plurality of drain electrodes 15. A power supply pad 42 is connected to the end of the voltage line 41. Further, the voltage line 41 passes through the insulating layer in the Z direction through the through hole 43, advances in the -X direction, and then bends in the -Y direction to reach the drain electrode 15. A first insulating layer 13 is provided between the gate electrode 12 and the source electrode 14 and the drain electrode 15 in the Z direction. Also, the gate electrode 12, the connection line 31, and the mesh conductor 32 are sandwiched between the first insulating layer 13 and the second insulating layer 2.

[0025] In the electrostatic sensor system using the one-dimensional electrostatic sensor of Example 4, by applying a selection potential to the power supply pad 42, the selection potential is applied to all the field effect transistors 1, and the current flowing through the output pad 63 is detected. The selection potential may be applied continuously or intermittently.

[0026] The extended gate 3 extends over a wider range than the gate electrode 12, particularly in the X direction. Therefore, charges efficiently accumulate on the gate electrode 12. Further, the one-dimensional electrostatic sensor of Example 2 can function as a two-dimensional electrostatic sensor by moving the detection surface in the Y direction. Specifically, the arranged extended gates 3 are brought close to or into contact with the detection target surface, and the one-dimensional electrostatic sensor is moved in the Y direction. At this time, if the field-effect transistor 1 is kept as far as possible from the detection surface, the static electricity on the detection surface is less likely to affect the field-effect transistor 1. Therefore, if the connection line 31 is bent in a direction away from the detection surface near the extended gate 3, the static electricity on the detection surface is less likely to directly affect the field-effect transistor 1. Furthermore, if the connection line 31 is made somewhat longer, the direct influence of the static electricity on the detection surface on the field-effect transistor 1 can be suppressed.

[0027] Also in this embodiment, the semiconductor 11 is an organic semiconductor, and the field-effect transistor 1 is an organic field-effect transistor (OFET). However, the semiconductor 11 can also be an inorganic semiconductor.

Example

[0028] Example 5 is also a one-dimensional electrostatic sensor in which sensors are arranged in a one-dimensional manner. FIG. 8 shows the one-dimensional electrostatic sensor of Example 5 having nine sensors. The nine sensors are arranged in the X direction, and a plurality of field-effect transistors 1 are also arranged in the X direction. The extended gates 3 are also arranged in the X direction. The configuration of the field-effect transistor 1 is the same as that of Example 4.

[0029] At the position of the field-effect transistor 1 in the Y direction, a plurality (three) of voltage lines 41 extending in the X direction and a plurality (three) of detection lines 61 are provided. Each of the voltage lines 41 branches and is electrically connected to a plurality of drain electrodes 15. A power supply pad 42 is connected to the end of each of the voltage lines 41. Each of the detection lines 61 also branches and is electrically connected to a plurality of source electrodes 14. An output pad 63 is connected to the end of each of the detection lines 61.

[0030] In the electrostatic sensor system using the one-dimensional electrostatic sensor of Example 5, a selection potential is sequentially scanned and applied to a plurality of power supply pads 42. A selection potential is sequentially applied to a plurality of field effect transistors 1, and a non-selection potential is applied to the power supply pads 42 to which the selection potential is not applied, thereby detecting the current flowing through the output pad 63. With such a configuration, although it is a one-dimensional electrostatic sensor, detection can be performed using scanning like a two-dimensional electrostatic sensor, and the number of terminals composed of the power supply pads 42 and the output pad 63 can be reduced. Further, in Example 5, since the selection potential is sequentially applied every other sensor, the simultaneously selected field effect transistors 1 are separated from each other, and interaction is less likely to occur during reading.

Example

[0031] In Example 6, as shown in FIG. 9, a field effect transistor 8 that is not affected by an electric field is used. FIG. 9 shows an example of an electrostatic sensor without a gate electrode 12 and an extended gate 3. The source electrode 82 of the field effect transistor 8 is connected to the negative electrode of the complementary power supply 44, and the drain electrode 83 is connected to the source electrode 14 of the field effect transistor 1. Then, the drain electrode 15 of the field effect transistor 1 is connected to the positive electrode of the power supply 4. Further, the source electrode 14 is connected to the ground 5 via the current detector 6. The conductive film 52, the negative electrode of the power supply 4, and the positive electrode of the complementary power supply 44 are also connected to the ground 5.

[0032] The field effect transistor 8 is a complementary transistor made in the same manner as the field effect transistor 1. In the detection direction (the -Z direction), the conductive film 52 is laminated only in the vicinity of the semiconductor 81 of the field effect transistor 8. Since the electric field from the -Z direction is shielded by the conductive film 52, the field effect transistor 8 is not affected by the electric field. Therefore, the currents flowing through the field effect transistor 1 and the field effect transistor 8 cancel each other out, reducing the current flowing in the state where there is no charged object 7, and improving the dynamic range.

[0033] FIG. 10 shows an example in which the technique of Example 6 is applied to a two-dimensional electrostatic sensor having an extended gate 3. In the electrostatic sensor of FIG. 10, a plurality of voltage lines 41 extending in the Y direction are arranged in the X direction, and a plurality of detection lines 61 extending in the X direction are arranged in the Y direction. Then, a field effect transistor 1 is provided near the intersection of the voltage line 41 and the detection line 61, with the drain connected to the voltage line 41 and the source connected to the detection line 61. The P-type field effect transistor 1 has its gate connected to the extended gate 3. Looking at one sensor, in the circuit of FIG. 9, a gate electrode 12 is provided under the semiconductor 11, and the gate electrode 12 is connected to the extended gate 3. Each of the detection lines 61 is connected to the ground 5 via a current detector 6 outside the electrostatic sensor. At the end of the region composed of a plurality of field effect transistors 1, a plurality of field effect transistors 8 are arranged in the Y direction. The field effect transistor 8 is of the N type, with its source electrode 82 connected to the complementary power supply line 441 and its drain electrode 83 connected to the detection line 61. Also, the region of the field effect transistor 8 is shielded by a conductive film 52. The field effect transistor 8 is not connected to a configuration corresponding to the extended gate 3.

[0034] A selection potential of -5V is sequentially applied to the plurality of voltage lines 41 from outside the electrostatic sensor, and a non-selection potential of 0V is applied to the voltage lines 41 to which the selection potential is not applied. Also, the potential supplied from the complementary power supply 44 to the complementary power supply line 441 is fixed at 5V. With such a circuit, the configuration as shown in FIG. 9 is realized in each row. Then, the currents flowing through the P-type field effect transistor 1 to which the selection potential is applied and the N-type field effect transistor 8 cancel each other out, reducing the current flowing in the state where there is no charged object 7 and improving the dynamic range.

[0035] The circuit of FIG. 10 does not connect the extending gate 3 to the field effect transistor 8 that operates complementarily, but the extending gate 3 may also be connected to the field effect transistor 8 and shielded with the conductive film 52 together with the field effect transistor 8. Further, the field effect transistor 8 and the conductive film 52 may be provided near each field effect transistor 1. A gate electrode may or may not be provided for the field effect transistor 8.

Embodiment

[0036] In Embodiment 7, one semiconductor layer common to a plurality of field effect transistors 16 is provided. FIG. 11 shows the structure of the two-dimensional electrostatic sensor of Embodiment 7. FIG. 11(a) is a partial plan view of one element, and FIG. 11(b) is a partial cross-sectional view along the extension line of the B-B line in FIG. 11(a). In FIG. 11, a plurality of voltage lines 41 extend in the X direction, and a plurality of detection lines 61 extend in the Y direction. The P-type field effect transistor 16 is provided near the intersection of the plurality of voltage lines 41 and the plurality of detection lines 61. As shown in FIG. 11(b), the electrostatic sensor of Embodiment 7 is provided with an extending gate 3 and a connection line 31 on the Z-facing surface of the third insulating layer 21 and is covered with the second insulating layer 2. Then, a gate electrode 162 and a voltage line 41 are provided on the Z-facing surface of the second insulating layer 2 and are covered with the first insulating layer 13. A through hole 33 is provided in the second insulating layer 2 to connect the gate electrode 162 and the connection line 31. The gate electrode 162 has a substantially disk shape with a recess provided in the X direction from the -X-facing side of the gate electrode 162.

[0037] On the surface of the first insulating layer 13 in the Z direction, a source electrode 163, a drain electrode 164, and a detection line 61 are provided. The source electrode 163 is annularly provided around the drain electrode 164 in the X-Y plane and connects the detection line 61 in the Y direction. The source electrode 163 and the drain electrode 164 partially overlap the gate electrode 162 when viewed from the Z direction. Also, the drain electrode 164 is electrically connected to the voltage line 41 through a through hole 45 provided in the first insulating layer 13. Then, a semiconductor layer 161 is formed over the entire surface of the first insulating layer 13 in the Z direction so as to cover the source electrode 163, the drain electrode 164, and the detection line 61. In Example 7, the semiconductor layer 161 is provided without being divided for each individual field-effect transistor 16, and manufacturing the electrostatic sensor is easier than when the semiconductor layer is divided. Note that in Example 7, the semiconductor layer 161 is formed of an organic semiconductor, but it may also be an inorganic semiconductor. Also, similar to Example 1, the electrostatic sensor of Example 7 has flexibility, but it does not necessarily have to have flexibility.

[0038] In Example 7, since a common semiconductor layer 161 is used for a plurality of field-effect transistors 16, the semiconductor layer 161 also exists between the field-effect transistors 16, and the resistance value changes due to an electric field. However, in Example 7, the source electrode 163 covers the periphery of the X-Y plane of the drain electrode 164. And since the potential fluctuation of the source electrode 163, which is the output side, is sufficiently small compared to the drain electrode 164, even if the resistance value between the source electrodes 163 becomes small, the flowing current is suppressed, the resolution is less likely to decrease, and the power consumption is also small. On the other hand, if the input side to which the voltage line 41 is connected is on the outside and the output line to which the detection line 61 is connected is on the inside, even if the resistance of the semiconductor layer 161 between adjacent field-effect transistors 16 decreases and a current flows, it does not affect the output current.

Example

[0039] Figure 12 shows a partial cross-sectional view of the two-dimensional electrostatic sensor of Example 8. The partial plan view of one element is the same as that in Fig. 11(a). Example 8 is obtained by providing the extending gate 3 and the connection line 31 on the surface of the second insulating layer 2 in the Z direction. The configuration corresponding to the third insulating layer 21 in Fig. 11 is not described and may or may not be present.

Example

[0040] Figure 13 shows a partial cross-sectional view of the two-dimensional electrostatic sensor of Example 9. In Example 9, a voltage line 41 extending in the X direction is provided on the surface of the semiconductor layer 171 in the Z direction via an insulating layer (not shown). The voltage line 41 is connected to the drain electrode 174 through a through hole 46 provided in the semiconductor layer 171. The gate electrode 172 provided on the surface of the second insulating layer 2 in the Z direction is disk-shaped. In addition, the shapes of the source electrode 173 and the drain electrode 174 of the field effect transistor 17 are the same as those of the source electrode 163 and the drain electrode 164 in Example 8.

[0041] <Detection by capacitance> When the present invention is used as a proximity sensor, proximity can be detected if there is a potential difference between the sensor and the object 7. Therefore, even when the object 7 is not charged or the potential of the object 7 is equal to the ground potential, by shifting the potential of the sensor (the average potential of the semiconductor layer 11 in the field effect transistor 1) from the ground potential to create a potential difference, the proximity of the object 7 can be detected. As examples of this invention, Example 10 and Example 11 for detecting proximity as a change in capacitance are described.

Example

[0042] In Example 10, the potential of the voltage line 41 is changed in the reverse direction to detect capacitance. In Fig. 14 showing Example 10, compared with the configuration of Fig. 1, it has a second power source 91 in the reverse direction to the power source 4 and a changeover switch 92. By switching the changeover switch 92, when the voltage of the voltage line 41 is positive (+V D ) and when it is negative (-V DPerform two measurements of (). At this time, the potentials of the semiconductor 11 are approximately +V D / 2 and -V D / 2. When the field-effect transistor 1 is in the linear region, the source currents at these times are

[0043]

Equation

[0044] respectively, and are detected by the current detector 6. Here, W is the channel width, L is the channel length, μ is the mobility of the semiconductor 11, C is the capacitance between the extended gate and the object 7, S is the overlapping area of the semiconductor 11 and the gate electrode 12, V o is the potential of the object 7, and V th is the gate threshold voltage of the field-effect transistor 1. The average I ave and the difference I dif of these two source currents are respectively

[0045]

Equation

[0046] respectively. After arranging with respect to the capacitance C and the potential V o of the object 7, we get

[0047]

Equation

[0048] That is, from equation (5), it becomes possible to obtain the capacitance C regardless of the value of the potential V o of the object 7. Since L, etc. are constants, C is a linear function of I dif , and the proximity of the object 7 can be detected from the change in the capacitance C.

[0049] In the method of Example 10, the proximity of the object 7 is detected as described above. Further, in the apparatus of Example 10, a processing device (not shown) switches the changeover switch 92 in FIG. 14 and A / D-converts and inputs the current value obtained by the current detector 6. Then, in the processing device into which two current values obtained by switching the changeover switch 92 are input, the change in the capacitance C is detected based on the change in the current difference I dif to detect the proximity of the object 7.

Example

[0050] In Example 11, the reference potential is shifted to detect the capacitance. In FIG. 15 showing Example 11, compared with the configuration of FIG. 1, a changeover switch 94 and an offset power supply 93 are provided between the reference potential line 95 and the ground 5. Then, two measurements are performed: when the changeover switch 94 connects the ground 5 and the reference potential line 95 so that the potential of the reference potential line 95 is 0 V, and when it is connected to the offset power supply 93 so that the potential of the reference potential line 95 is V offset . At this time, the potentials of the semiconductor 11 are approximately -V D / 2 and -V D / 2 + V offset , respectively. When the transistor is in the linear region, the source currents at these times are

[0051]

Equation

[0052] and are detected by the current detector 6. W, etc. are the same as in Example 10. The average I ave and the difference I dif of these two source currents are respectively

[0053]

Equation

[0054] and, when arranged in terms of the capacitance C and the potential V o of the object 7,

[0055]

Number

[0056] is. Then, according to equation (11), the capacitance C can be obtained regardless of the value of the potential V of the object 7. Since L and the like are constants, C is a linear function of I, and the proximity of the object 7 can be detected from the change in the capacitance C. o The method of Example 11 detects the proximity of the object 7 as described above. Also, in the apparatus of Example 11, a processing device (not shown) switches the changeover switch 94 in FIG. 15 and A / D-converts and inputs the current value obtained by the current detector 6. Then, in the processing device into which the two current values obtained by switching the changeover switch 94 are input, the change in the capacitance C is detected from the change in the difference I dif of the current values, and the proximity of the object 7 is detected.

[0057] dif dif dif

[0058] As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to these embodiments, and design changes and the like within the scope not departing from the gist of the present invention are also included in the present invention. Also, the above-described embodiments can be combined by diverting each other's technologies as long as there are no particular contradictions or problems in their purposes and configurations. For example, the inventions of Examples 10 and 11 can be applied to the inventions prior to Example 9. Also, the power supply may be electrically connected to one of the source or drain in the field effect transistor, and the current detector may be electrically connected to the other of the source or drain. The field effect transistor may be P-type as shown in the examples, or N-type. In the case of P-type, it is preferable to apply a voltage lower than the source to the drain as the selection potential and detect the source current. In the case of N-type, it is preferable to apply a potential higher than the source to the drain as the selection potential and detect the source current. The power supply 4 and the current detector 6 may be provided separately from the electrostatic sensor or integrally.

Explanation of Signs

[0059] 1 Field-effect transistor 11 Semiconductor 12 Gate electrode 13 First insulating layer 14 Source electrode 15 Drain electrode 16 Field-effect transistor 161 Semiconductor layer 162 Gate electrode 163 Source electrode 164 Drain electrode 17 Field-effect transistor 171 Semiconductor layer 172 Gate electrode 173 Source electrode 174 Drain electrode 2 Second insulating layer 21 Third insulating layer 3 Extending gate 31 Connection line 32 Mesh conductor 33 Through hole 4 Power supply 41 Voltage line 42 Power supply pad 43 Through hole 44 Complementary power supply 441 Complementary power supply line 45 Through hole 46 Through hole 5 Ground 51 Conductive film 52 Conductive film 6 Current detector 61 Detection line 62 Through hole 63 Output pad 7 Object 8 Field-effect transistor 81 Semiconductor 82 Source electrode 83 Drain electrode 91 Second power supply 92 Switching switch 93 Offset power supply 94 Switching switch 95 Reference potential line S Original signal Signal with Sn power supply noise superimposed

Claims

1. A predetermined number of voltage lines, a plurality of detection lines, a plurality of extending gates, a field-effect transistor corresponding to each of the extending gates and connected to any one of the predetermined number of the voltage lines and any one of the plurality of detection lines, comprising: each of the extending gates is electrically connected to the gate electrode of the corresponding field-effect transistor, the extending gates are arranged in a one-dimensional manner, and the field-effect transistors corresponding to the adjacent predetermined number of extending gates are grouped. In each individual group, all of the plurality of field-effect transistors are connected to one of the plurality of detection lines, and in each individual group, each of the predetermined number of field-effect transistors is separately connected to one of the predetermined number of voltage lines, an electrostatic sensor characterized in that when a selection potential is applied to the field-effect transistor by the voltage line, the static electricity in the vicinity of the extending gate is detected by the current flowing through the detection line.

2. The electrostatic sensor according to claim 1, wherein the extending gate has a width wider than that of the gate electrode.

3. The electrostatic sensor according to claim 1 or 2, characterized in that a connection line is provided extending in the extending direction of the gate electrode, and the extending gate is provided on the opposite side of the gate electrode in the connection line.

4. The electrostatic sensor according to any one of claims 1 to 3, wherein the extending gate is formed in a mesh shape.

5. The electrostatic sensor according to any one of claims 1 to 4, a power supply electrically connected to the voltage line, and a current detector electrically connected to the detection line, characterized in that it comprises an electrostatic sensor system.

6. The power supply applies a selection potential to one of the predetermined number of voltage lines and a non-selection potential to the other voltage lines, The electrostatic sensor system according to claim 5, characterized in that static electricity is detected by detecting a current by the current detector connected to the detection line.

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