Touch sensor and touch input device

Abstract

A touch sensor comprises: a piezoelectric film that has a first main surface and a second main surface arranged in the vertical direction; a plurality of signal electrodes that are provided on the first main surface; and a reference electrode that is provided on the second main surface and overlaps each of the plurality of signal electrodes as seen in the vertical direction. The piezoelectric film includes a piezoelectric body that is stretched in a stretching direction. The signal electrodes each have a dead zone in which an electric charge generated in the signal electrode becomes zero. The plurality of signal electrodes are arranged at intervals from each other along a lateral direction that is orthogonal to the vertical direction and / or a longitudinal direction that is orthogonal to both the vertical direction and the lateral direction. The stretching direction is parallel to the lateral direction or the longitudinal direction.

Description

Touch Sensor and Touch Input Device

[0001] The present invention relates to a touch sensor and a touch input device.

[0002] As conventional inventions related to touch sensors and touch input devices, for example, the multi-directional key switch described in Patent Document 1 and the touch input device described in Patent Document 2 are known. The multi-directional key switch described in Patent Document 1 includes a center switch and an outer peripheral switch composed of a plurality of first-stage switches and a plurality of second-stage switches arranged on a common circumference outside the center switch.

[0003] The touch input device described in Patent Document 2 includes a touch panel made of a molecularly oriented polylactic acid film and a processing device. Electrodes are formed on the first main surface and the second main surface of the polylactic acid film. The electrodes on the first main surface are divided electrodes electrically divided into at least four. Each of the divided electrodes is connected to the processing device.

[0004] The processing device outputs position information and / or pressing information based on voltages detected independently from the divided electrodes. Specifically, the processing device includes a detection unit, a storage unit, and a calculation unit. The detection unit detects each voltage generated in the divided electrodes. The storage unit stores a plurality of stored voltage patterns obtained in advance from the voltages generated in the divided electrodes and position information corresponding to the stored voltage patterns. The calculation unit creates a detected voltage pattern from each voltage detected by the detection unit. The calculation unit compares the detected voltage pattern with the stored voltage patterns stored in the storage unit, and collates the voltage patterns that match with a predetermined threshold value to output position information.

[0005] Japanese Unexamined Patent Application Publication No. 11-162298 International Publication No. 2010 / 143528

[0006] In the multi-directional key switch described in Patent Document 1, a plurality of switches are required. In the touch input device described in Patent Document 2, the computational load of the processing device becomes large.

[0007] Therefore, the object of the present invention is to provide a touch sensor and a touch input device with a simpler configuration and lower computational load.

[0008] A touch sensor according to one embodiment of the present invention comprises: a piezoelectric film having a first main surface and a second main surface arranged in the vertical direction; a plurality of signal electrodes provided on the first main surface; and a reference electrode provided on the second main surface, which overlaps with each of the plurality of signal electrodes when viewed in the vertical direction; wherein the piezoelectric film includes a piezoelectric body stretched in the stretching direction; the signal electrodes have a dead zone where the charge generated on the signal electrodes is zero; the plurality of signal electrodes are spaced apart from each other along the left-right direction perpendicular to the vertical direction, and / or the front-back direction perpendicular to the vertical direction and the left-right direction; and the stretching direction is parallel to the left-right direction or the front-back direction.

[0009] Because the extension direction of the piezoelectric material is parallel to the left-right or front-back direction, when viewed from below, with the touch position as the reference point, the polarity of the charge generated on the portion of the first main surface located at +45 degrees to the right can be made equal to the polarity of the charge generated on the portion of the first main surface located at +45 degrees to the left, and the polarity of the charge generated on the portions of the first main surface located at -45 degrees to the right and -45 degrees to the left can be made opposite. Therefore, by arranging multiple signal electrodes at intervals from each other along the left-right and / or front-back directions, multiple touch areas with different charge polarity patterns generated on the multiple signal electrodes can be arranged along the left-right and front-back directions. Because the charge polarity patterns generated on the multiple signal electrodes are different from each other, there is a one-to-one correspondence between the touch area where the touch operation is performed and the charge polarity patterns generated on the multiple signal electrodes.

[0010] Therefore, a touch sensor according to one embodiment of the present invention can detect multiple touch areas using a single piezoelectric film. Furthermore, when determining a touch area containing a touch position using a touch sensor according to one embodiment of the present invention, details of the magnitude of the charge generated at the multiple signal electrodes are not required; only the polarity of the charge generated at the multiple signal electrodes is necessary.

[0011] On the other hand, the multi-directional key switch described in Patent Document 1 (Japanese Patent Application Publication No. 11-162298) required multiple switches. Therefore, the configuration of the touch sensor according to one embodiment of the present invention is simpler compared to the multi-directional key switch described in Patent Document 1.

[0012] Furthermore, in the touch input device described in Patent Document 2 (International Publication No. 2010 / 143528), the memory unit stores multiple stored voltage patterns, which are predetermined from the voltages generated at each divided electrode, and position information corresponding to those stored voltage patterns. The calculation unit creates a detected voltage pattern from each voltage detected by the detection unit. The calculation unit compares the detected voltage pattern with the stored voltage patterns stored in the memory unit, matches the voltage patterns with a predetermined threshold, and outputs the position information. Therefore, the determination of a touch area including a touch position TP using a touch sensor according to one embodiment of the present invention is simpler and has a lower computational load compared to the calculation of position information in the touch input device described in Patent Document 2.

[0013] According to the present invention, a simpler configuration can be used, and the computational load can be reduced.

[0014] Figure 1 is a block diagram of the touch input device 10. Figure 2 is an exploded perspective view of the touch input device 10. Figure 3 is a plan view of the touch input device 10. Figure 4 is a plan view showing an example of the distribution of charge polarity generated on the upper main surface US2 of the piezoelectric film 2 when a touch operation is performed on the touched member 9. Figure 5 is a diagram showing an example of the relationship between each touch position and the charge polarity generated on each signal electrode. Figure 6 is a plan view showing the dead zones D11 and D21 of the signal electrode 5a. Figure 7 is a plan view of a modified example of the touch input device 10. Figure 8 is a plan view of the touch input device 10a. Figure 9 is a diagram showing an example of the relationship between each touch position and the charge polarity generated on each signal electrode in the touch sensor 1a. Figure 10 is a plan view of the touch input device 10b. Figure 11 is a diagram showing an example of the relationship between each touch position and the charge polarity generated on each signal electrode in the touch sensor 1b. Figure 12 is a perspective view of the touched member 9 related to the touch input device 10c. Figure 13 is a cross-sectional view of the touch input device 10c. Figure 14 is a plan view of the touch input device 10d. Figure 15 is a diagram showing an example of the relationship between each touch position and the polarity of the charge generated at each signal electrode in the touch sensor 1d. Figure 16 is a block diagram of the touch input device 10e. Figure 17 is a plan view of the touch input device 10e. Figure 18 is a diagram showing an example of the relationship between each touch position and the polarity of the charge generated at each signal electrode and each outer electrode. Figure 19 is a diagram showing an example of the relationship between each touch position and the polarity of the charge generated at each signal electrode and each outer electrode. Figure 20 is a plan view of one modified example of the touch input device 10e. Figure 21 is a plan view of one modified example of the touch input device 10e. Figure 22 is a diagram showing the signal electrode and outer electrode necessary for determining the touch position TP. Figure 23 is a plan view of the touch input device 10f, which combines the structures of the touch input devices 10a and 10e. Figure 24 is a plan view of a touch input device 10g that combines the structures of touch input devices 10b and 10e. Figure 25 is a plan view showing the arrangement of outer peripheral electrodes when the touch area is one row.

[0015] [First Embodiment] Below, a touch sensor 1 and a touch-type input device 10 according to the first embodiment of the present invention will be described with reference to the drawings. Figure 1 is a block diagram of the touch-type input device 10. Figure 2 is an exploded perspective view of the touch-type input device 10.

[0016] In the touch-type input device 10, as an example, directions are defined as follows: As shown in Figure 2, the direction in which the upper main surface US2 and the lower main surface DS2 are aligned is defined as the up-down direction. The direction in which the signal electrodes 5a and 5b are aligned is defined as the left-right direction. The direction in which the signal electrodes 5a and 5c are aligned is defined as the front-back direction. The up-down direction, left-right direction and front-back direction are orthogonal to each other. However, the up-down direction, left-right direction and front-back direction in this specification are directions defined for the convenience of explanation and do not necessarily coincide with the up-down direction, left-right direction and front-back direction when the touch-type input device 10 is in use. Also, in each drawing, the up direction and down direction may be swapped, the left direction and right direction may be swapped, and the front direction and back direction may be swapped.

[0017] As shown in Figures 1 and 2, the touch input device 10 comprises a touch sensor 1, a touched member 9, and a determination circuit 11. The user performs a touch operation on the touched member 9 using their finger or a pen. As shown in Figure 1, the touch sensor 1 outputs output signals S1 to S4 in response to the user's touch operation. The output signals S1 to S4 are input to the determination circuit 11. The determination circuit 11 includes a determination unit 111 and a storage unit 112. Details of the determination circuit 11 will be described later.

[0018] As shown in Figure 2, in this embodiment, the touched member 9 is plate-shaped. The touched member 9 is, for example, a touch panel or the housing of an electronic device. The touched member 9 has an upper main surface US9 and a lower main surface DS9 arranged in the vertical direction. The user performs a touch operation on the upper main surface US9. The upper main surface US9 and the lower main surface DS9 are rectangular in shape, each having a front and rear edge extending in the left-right direction, and a left and right edge extending in the front-back direction. Note that the touched member 9 does not have to be plate-shaped. Also, the upper main surface US9 and the lower main surface DS9 do not have to be rectangular in shape.

[0019] The touch sensor 1 is in the form of a flat film. The touch sensor 1 is flexible. The touch sensor 1 comprises a piezoelectric film 2, a reference electrode 3, coverlays 4 and 8, signal electrodes 5a to 5d, a substrate 6, and a shielding member 7. Therefore, the touch sensor 1 has four signal electrodes. In this invention, the coverlays 4 and 8, the substrate 6, and the shielding member 7 are not essential components. Furthermore, the touch sensor 1 is not limited to four signal electrodes; it may have multiple signal electrodes.

[0020] The piezoelectric film 2 has an upper main surface US2 and a lower main surface DS2 arranged in the vertical direction. The upper main surface US2 and the lower main surface DS2 are rectangular in shape, each having a front and rear edge extending in the left-right direction, and a left and right edge extending in the front-back direction. The upper main surface US2 corresponds to the first main surface according to the present invention. The lower main surface DS2 corresponds to the second main surface according to the present invention. Note that the shape of the piezoelectric film 2 is not limited to the shape shown in this embodiment.

[0021] The piezoelectric film 2 becomes polarized upon deformation, generating electric charge on its upper main surface US2 and lower main surface DS2. The amount of electric charge generated on the upper main surface US2 and lower main surface DS2 depends on the amount of deformation of the piezoelectric film 2.

[0022] The piezoelectric film 2 contains a piezoelectric material. The piezoelectric material is, for example, a chiral polymer. The chiral polymer is, for example, polylactic acid (PLA) such as L-type polylactic acid (PLLA) and D-type polylactic acid (PDLA). The main chain of PLA has a helical structure. PLA has piezoelectric properties when its molecules are oriented by uniaxial stretching. The piezoelectric film 2 has a piezoelectric constant of d14. Note that the piezoelectric material is not limited to a chiral polymer.

[0023] The PLA is stretched in the stretching direction OD. The stretching direction OD of the PLA is parallel to the left-right direction. In this embodiment, the stretching direction OD of the PLA is to the right. Note that the stretching direction OD of the PLA only needs to be approximately parallel to the left-right direction, and when viewed from below, it may form an angle within a range of approximately ±10 degrees with respect to the left-right direction. Alternatively, the stretching direction OD of the PLA may be parallel to the front-back direction. In this case, the stretching direction OD of the PLA only needs to be approximately parallel to the front-back direction, and when viewed from below, it may form an angle within a range of approximately ±10 degrees with respect to the front-back direction.

[0024] The piezoelectric film 2 generates electric charge on its upper main surface US2 and lower main surface DS2 when stretched or compressed. When a user touches the upper main surface US9 of the touched member 9, the piezoelectric film 2 is stretched or compressed, generating electric charge on its upper main surface US2 and lower main surface DS2. When the upper main surface US9 is touched, the polarity of the charge generated on the portion of the upper main surface US2 located at a +45 degree angle to the right of the touch position TP, when viewed from below, is equal to the polarity of the charge generated on the portion of the upper main surface US2 located at a +45 degree angle to the left of the touch position TP. Note that, when viewed from below, counterclockwise is considered positive and clockwise is considered negative. When viewed downwards, the polarity of the charge generated on the upper principal surface US2 located at a -45 degree angle to the right of the touch position TP is equal to the polarity of the charge generated on the upper principal surface US2 located at a -45 degree angle to the left of the touch position TP. On the other hand, when viewed downwards, the polarity of the charge generated on the upper principal surface US2 located at a +45 degree angle to the right of the touch position TP is the opposite polarity of the charge generated on the upper principal surface US2 located at a -45 degree angle to the right of the touch position TP.

[0025] In this embodiment, when a touch operation is performed on the upper main surface US9, the polarity of the charge generated in the portion of the upper main surface US2 located at +45 degrees to the right and +45 degrees to the left, relative to the touch position TP when viewed downwards, is positive. Also, the polarity of the charge generated in the portion of the upper main surface US2 located at -45 degrees to the right and -45 degrees to the left, relative to the touch position TP when viewed downwards, is negative. If the extension direction OD of the PLA is to the left, the polarity of the charge generated in the portion of the upper main surface US2 located at +45 degrees to the right and +45 degrees to the left, relative to the touch position TP when viewed downwards, can be made negative, and the polarity of the charge generated in the portion of the upper main surface US2 located at -45 degrees to the right and -45 degrees to the left, relative to the touch position TP, can be made positive.

[0026] The reference electrode 3 is conductive. The material of the reference electrode 3 is, for example, copper. The reference electrode 3 is provided on the lower main surface DS2 of the piezoelectric film 2. The reference electrode 3 covers the entire lower main surface DS2. By being connected to the ground potential of the determination circuit 11, the reference electrode 3 functions as a reference electrode and a shielding conductor. Note that the reference electrode 3 does not necessarily have to cover the entire lower main surface DS2 of the piezoelectric film 2.

[0027] Each of the signal electrodes 5a to 5d is conductive. The material of each of the signal electrodes 5a to 5d is, for example, copper. Each of the signal electrodes 5a to 5d is rectangular in shape, with a front and rear edge extending in the left and right directions, and a left and right edge extending in the front and back directions, when viewed in the vertical direction. Each of the signal electrodes 5a to 5d is provided on the upper main surface US2 of the piezoelectric film 2. Therefore, each of the signal electrodes 5a to 5d overlaps with the reference electrode 3 when viewed in the vertical direction. Each of the signal electrodes 5a to 5d functions as a signal electrode for outputting the charge generated by the piezoelectric film 2 as output signals S1 to S4. Details of the arrangement of the signal electrodes 5a to 5d will be described later. Note that the shape of the signal electrodes 5a to 5d is not limited to the shape shown in this embodiment. The shapes of the signal electrodes 5a to 5d do not have to be the same as each other.

[0028] The coverlay 4 is insulating. The coverlay 4 is provided on the upper main surface US2 of the piezoelectric film 2. More specifically, the coverlay 4 covers the upper main surface US2 except for the portion where the signal electrodes 5a to 5d are provided. Note that there may be portions of the coverlay 4 that are not provided other than the portion where the signal electrodes 5a to 5d are provided.

[0029] The base material 6 is insulating. The material of the base material 6 is, for example, polyimide. The base material 6 has an upper main surface and a lower main surface aligned in the vertical direction. The upper and lower main surfaces of the base material 6 are rectangular in shape, each having a front and rear edge extending in the left-right direction, and a left and right edge extending in the front-back direction. A wiring layer (not shown) is formed on the lower main surface of the base material 6. The signal electrodes 5a to 5d are each electrically connected to their respective electrically independent wirings and are connected to the determination circuit 11 via these wirings. As a result, the output signals S1 to S4 of the signal electrodes 5a to 5d are input to the determination circuit 11.

[0030] The shielding member 7 is conductive. The shielding member 7 has an upper main surface and a lower main surface aligned in the vertical direction. The upper and lower main surfaces of the shielding member 7 are rectangular in shape, each having a front and rear edge extending in the left-right direction, and a left and right edge extending in the front-back direction. The shielding member 7 is provided on the upper main surface of the base material 6. The shielding member 7 covers the entire upper main surface of the base material 6. The shielding member 7 functions as a shielding conductor by being connected to the ground potential. Note that the shielding member 7 does not necessarily have to cover the entire upper main surface of the base material 6.

[0031] The coverlay 8 is insulating. The coverlay 8 has an upper main surface and a lower main surface aligned in the vertical direction. The upper and lower main surfaces of the coverlay 8 are rectangular in shape, each having a front edge and a rear edge extending in the left-right direction, and a left edge and a right edge extending in the front-back direction. The upper main surface of the coverlay 8 is attached to the lower main surface DS9 of the touched member 9, so that the piezoelectric film 2 is aligned with the lower main surface DS9.

[0032] Figure 3 is a plan view of the touch input device 10. As shown in Figure 3, the signal electrodes 5a to 5d are arranged with spacing between them along the left-right and front-back directions. In other words, the signal electrodes 5a to 5d are arranged in a 2x2 grid with spacing between them along the left-right and front-back directions.

[0033] The signal electrodes 5a to 5d are positioned such that, when viewed in the vertical direction, their centers coincide with the centers of the piezoelectric film 2. In other words, when viewed in the vertical direction, the signal electrodes 5a to 5d are positioned in the center of the upper main surface US2 of the piezoelectric film 2. Also, when viewed in the vertical direction, the signal electrodes 5a to 5d are surrounded by the outer edge OS2 of the piezoelectric film 2. As a result, when viewed in the vertical direction, there is a clearance between the signal electrodes 5a to 5d and the outer edge OS2 of the piezoelectric film 2. Note that the signal electrodes 5a to 5d are not necessarily positioned so that, when viewed in the vertical direction, their centers coincide with the centers of the piezoelectric film 2. Therefore, when viewed in the vertical direction, the signal electrodes 5a to 5d are not necessarily positioned in the center of the upper main surface US2 of the piezoelectric film 2.

[0034] When viewed in the vertical direction, the shortest distance between the signal electrodes 5a to 5d and the outer edge OS2 of the piezoelectric film 2 is 10% or more of the length of the piezoelectric film 2 along the direction of the shortest distance. If there are multiple portions where the shortest distance between the signal electrodes 5a to 5d and the outer edge OS2 of the piezoelectric film 2 exists when viewed in the vertical direction, it is sufficient that for each portion, the shortest distance between the signal electrodes 5a to 5d and the outer edge OS2 of the piezoelectric film 2 is 10% or more of the length of the piezoelectric film 2 along the direction of the shortest distance.

[0035] In this embodiment, when viewed in the vertical direction, the distance Lmin1 in the front-to-back direction between the front edge of signal electrode 5a or signal electrode 5b and the front edge of piezoelectric film 2, the distance Lmin2 in the front-to-back direction between the rear edge of signal electrode 5c or signal electrode 5d and the rear edge of piezoelectric film 2, the distance Lmin3 in the left-to-right direction between the left edge of signal electrode 5a or signal electrode 5c and the left edge of piezoelectric film 2, and the distance Lmin4 in the left-to-right direction between the right edge of signal electrode 5b or signal electrode 5d and the right edge of piezoelectric film 2 correspond to the shortest distance between the signal electrodes 5a to 5d and the outer edge OS2 of piezoelectric film 2, respectively.

[0036] Viewed in the vertical direction, the distance Lmin1 in the front-to-back direction between the front edge of signal electrode 5a or signal electrode 5b and the front edge of piezoelectric film 2 is 10% or more of the length L9FB of piezoelectric film 2 in the front-to-back direction (the direction of the shortest distance). The distance Lmin2 in the front-to-back direction between the rear edge of signal electrode 5c or signal electrode 5d and the rear edge of piezoelectric film 2 is 10% or more of the length L9FB of piezoelectric film 2 in the front-to-back direction (the direction of the shortest distance). Here, the length L9FB of piezoelectric film 2 in the front-to-back direction is the length of the left and right edges of piezoelectric film 2.

[0037] When viewed in the vertical direction, the distance Lmin3 in the horizontal direction between the left side of signal electrode 5a or the left side of signal electrode 5c and the left side of piezoelectric film 2 is 10% or more of the length L9FR of piezoelectric film 2 in the horizontal direction (the direction of the shortest distance). The distance Lmin4 in the horizontal direction between the right side of signal electrode 5b or the right side of signal electrode 5d and the right side of piezoelectric film 2 is 10% or more of the length L9FR of piezoelectric film 2 in the horizontal direction (the direction of the shortest distance). Here, the length L9FR of piezoelectric film 2 in the horizontal direction is the length of the front and rear sides of piezoelectric film 2.

[0038] The touched member 9 has touch areas A1 to A9 on its upper main surface US9. The boundary between adjacent touch areas A1 to A9 is one of the dead zones D11, D12, D21, or D22. The touch areas A1 to A9 are arranged in a 3x3 matrix along the left-right and front-back directions. Each of the touch areas A1 to A9 is rectangular in shape. Details of the dead zones D11, D12, D21, and D22 will be described later. Note that each of the touch areas A1 to A9 does not have to be rectangular.

[0039] Touch area A5 is the area enclosed by dead zones D11, D12, D21, and D22 when viewed in the vertical direction. Touch area A5 is located in the center of the piezoelectric film 2 when viewed in the vertical direction.

[0040] Touch area A1 is the region enclosed by the left and front edges of the piezoelectric film 2, as well as the dead zones D11 and D21, when viewed in the vertical direction. Touch area A1 is located to the left and in front of touch area A5.

[0041] Touch area A2 is the area enclosed by the front edge of the piezoelectric film 2 and the dead zones D11, D12, and D21 when viewed in the vertical direction. Touch area A2 is located in front of touch area A5 and to the right of touch area A1. The boundary between touch area A2 and touch area A5 is the dead zone D21. The boundary between touch area A2 and touch area A1 is the dead zone D11.

[0042] Touch area A3 is the area enclosed by the front and right edges of the piezoelectric film 2, as well as the dead zones D12 and D21, when viewed in the vertical direction. Touch area A3 is located to the right and in front of touch area A5, and to the right of touch area A2. The boundary between touch area A3 and touch area A2 is the dead zone D12.

[0043] Touch area A4 is the area enclosed by the left edge of the piezoelectric film 2 and the dead zones D11, D21, and D22 when viewed in the vertical direction. Touch area A4 is located to the left of touch area A5 and behind touch area A1. The boundary between touch area A4 and touch area A5 is dead zone D11. The boundary between touch area A4 and touch area A1 is dead zone D21.

[0044] When viewed in the vertical direction, the touch area A6 is an area surrounded by the right side of the piezoelectric film 2 and the insensitive zones D12, D21, and D22. The touch area A6 is located to the right of the touch area A5 and behind the touch area A3. The boundary between the touch area A6 and the touch area A5 is the insensitive zone D12. The boundary between the touch area A6 and the touch area A3 is the insensitive zone D21.

[0045] When viewed in the vertical direction, the touch area A7 is an area surrounded by the left side and the rear side of the piezoelectric film 2 and the insensitive zones D11, D22. The touch area A7 is located to the left rear of the touch area A5 and behind the touch area A4. The boundary between the touch area A7 and the touch area A4 is the insensitive zone D22.

[0046] When viewed in the vertical direction, the touch area A8 is an area surrounded by the rear side of the piezoelectric film 2 and the insensitive zones D11, D12, D22. The touch area A8 is located behind the touch area A5 and to the right of the touch area A7. The boundary between the touch area A8 and the touch area A5 is the insensitive zone D22. The boundary between the touch area A8 and the touch area A7 is the insensitive zone D11.

[0047] When viewed in the vertical direction, the touch area A9 is an area surrounded by the right side and the rear side of the piezoelectric film 2 and the insensitive zones D12, D22. The touch area A9 is located to the right rear of the touch area A5, behind the touch area A6, and to the right of the touch area A8. The boundary between the touch area A9 and the touch area A6 is the insensitive zone D22. The boundary between the touch area A9 and the touch area A8 is the insensitive zone D12.

[0048] FIG. 4 is a plan view showing an example of the distribution of the polarities of charges generated on the upper main surface US2 of the piezoelectric film 2 when a touch operation is performed on the touched member 9. As described above, the user performs a touch operation on the upper main surface US9 of the touched member 9. Also, when a touch operation is performed on the upper main surface US9, when viewed downward, positive charges are generated in the portions of the upper main surface US2 located in the direction of +45 degrees with respect to the right direction and in the direction of +45 degrees with respect to the left direction, with the touch position TP as a reference, and negative charges are generated in the portions of the upper main surface US2 located in the direction of -45 degrees with respect to the right direction and in the direction of -45 degrees with respect to the left direction. Therefore, when the user performs a touch operation on the center of the upper main surface US9, as shown in FIG. 4A, negative charges are generated in the signal electrodes 5a and 5d, and positive charges are generated in the signal electrodes 5b and 5c. Similarly, when the user performs a touch operation on the touch area A5, negative charges are generated in the signal electrodes 5a and 5d, and positive charges are generated in the signal electrodes 5b and 5c.

[0049] When the user performs a touch operation on the touch area A2, as shown in FIG. 4B, positive charges are generated in the signal electrode 5a, and negative charges are generated in the signal electrode 5b. Substantially no charges are generated in the signal electrodes 5c and 5d.

[0050] When the user performs a touch operation on the touch area A6, as shown in FIG. 4C, negative charges are generated in the signal electrode 5b, and positive charges are generated in the signal electrode 5d. Substantially no charges are generated in the signal electrodes 5a and 5c.

[0051] FIG. 5 is a diagram showing an example of the relationship between each touch position and the polarity of the charges generated in each signal electrode. In FIG. 5, 0 indicates no polarity. As shown in FIG. 5, when a touch operation is performed on each of the touch areas A1 to A9, the patterns of the polarities of the charges generated in the signal electrodes 5a to 5d are different, and the touch areas A1 to A9 where the touch operation is performed and the patterns of the polarities of the charges generated in the signal electrodes 5a to 5d correspond one-to-one. Also, when a touch operation is performed on the touch areas A2, A4 to A6, and A8, there are two or more signal electrodes that generate charges.

[0052] As described above, the determination circuit 11 includes a determination unit 111 and a storage unit 112. The determination unit 111 is, for example, an MPU (Micro Processing Unit). The determination unit 111 is implemented as software for the MPU. The output signals S1 to S4 of the signal electrodes 5a to 5d are input to the determination unit 111. The storage unit 112 has, for example, a ROM (Read Only Memory) and a RAM (Random Access Memory). The storage unit 112 stores as data the relationship between each touch position shown in Figure 5 and the polarity of the charge generated at each signal electrode. The determination unit 111 reads the program stored in the ROM into the RAM. The determination unit 111 may also be implemented as hardware using a comparator or the like.

[0053] First, the determination unit 111 determines the polarity of each output signal S1 to S4 based on the respective output signals S1 to S4 of the signal electrodes 5a to 5d. Next, the determination unit 111 determines the touch area that includes the touch position TP based on the polarity of each output signal S1 to S4. Furthermore, the determination unit 111 outputs a determination result indicating the touch area that includes the touch position TP.

[0054] Furthermore, with respect to the output signals S1 to S4 of each of the signal electrodes 5a to 5d, the determination unit 111 may consider the output signals to be nonpolar if the absolute value of the output signals S1 to S4 is less than a predetermined threshold.

[0055] For example, if the polarities of the output signals S1 to S4 are (negative, 0, 0, 0) in order, the determination unit 111 determines that the touch position TP is included in the touch area A1 and outputs a determination result indicating the touch area A1 in which the touch position TP is included.

[0056] For example, if the polarities of the output signals S1 to S4 are in order (negative, positive, positive, negative), the determination unit 111 determines that the touch position TP is included in the touch area A5 and outputs a determination result indicating the touch area A5 in which the touch position TP is included.

[0057] Similarly, for touch regions A1 to A9, the determination unit 111 outputs a determination result indicating the touch region that includes the touch position TP, based on the polarity of the respective output signals S1 to S4 of the signal electrodes 5a to 5d.

[0058] Figure 6 is a plan view showing the dead zones D11 and D21 of the signal electrode 5a. Each signal electrode has a dead zone where the charge generated on the signal electrode is zero. The dead zone is the boundary between regions where charge is generated, both on and near each signal electrode when viewed in the vertical direction. First, the dead zones D11 and D21 of the signal electrode 5a will be explained.

[0059] As described above, when a touch operation is performed on the upper main surface US9 of the touched member 9, a positive charge is generated on the portion of the upper main surface US2 located at +45 degrees to the right and +45 degrees to the left of the touch position TP when viewed from below, and a negative charge is generated on the portion of the upper main surface US2 located at -45 degrees to the right and -45 degrees to the left of the touch position TP. Furthermore, the signal electrode 5a is rectangular when viewed from above. Therefore, for example, as shown in Figure 6, when viewed in the vertical direction, if the touch position TP coincides with the center of the signal electrode 5a, when viewed in the downward direction, the absolute value of the positive charge generated on the part of the signal electrode 5a located at +45 degrees to the right and +45 degrees to the left relative to the touch position TP coincides with the absolute value of the negative charge generated on the part of the signal electrode 5a located at -45 degrees to the right and -45 degrees to the left relative to the touch position TP. As a result, the positive and negative charges cancel each other out, and the charge generated on the signal electrode 5a becomes zero.

[0060] Similarly, when viewed in the vertical direction, if the touch position TP is located on a straight line passing through the center of the signal electrode 5a and parallel to the front-to-back direction, the absolute values ​​of the positive charge and the negative charge generated on the signal electrode 5a will be the same, and the positive and negative charges will cancel each other out, resulting in zero charge being generated on the signal electrode 5a. When viewed in the vertical direction, the straight line passing through the center of the signal electrode 5a and parallel to the front-to-back direction is the dead zone D11.

[0061] Similarly, when viewed in the vertical direction, if the touch position TP is located on a straight line passing through the center of the signal electrode 5a and parallel to the horizontal direction, the absolute values ​​of the positive charge and the negative charge generated on the signal electrode 5a will be the same, and the positive and negative charges will cancel each other out, resulting in zero charge being generated on the signal electrode 5a. When viewed in the vertical direction, the straight line passing through the center of the signal electrode 5a and parallel to the horizontal direction is the dead zone D21.

[0062] Based on the above, the signal electrode 5a has dead zones D11 and D21 where the charge generated on the signal electrode 5a is zero.

[0063] Similarly, the signal electrode 5b has dead zones D12 and D21 where the charge generated on the signal electrode 5b is zero. The dead zone D12 is a straight line passing through the center of the signal electrode 5b and parallel to the front-to-back direction. Furthermore, when viewed in the vertical direction, the straight line passing through the center of the signal electrode 5a and parallel to the left-to-right direction also passes through the center of the signal electrode 5b. Therefore, the dead zone D21 is common to both signal electrodes 5a and 5b.

[0064] Similarly, the signal electrode 5c has dead zones D11 and D22 where the charge generated on the signal electrode 5c is zero. The dead zone D22 is a straight line passing through the center of the signal electrode 5c and parallel to the left-right direction. Furthermore, when viewed in the vertical direction, the straight line passing through the center of the signal electrode 5a and parallel to the front-back direction also passes through the center of the signal electrode 5c. Therefore, the dead zone D11 is common to both the signal electrodes 5a and 5c.

[0065] Similarly, the signal electrode 5d has dead zones D12 and D22 where the charge generated on the signal electrode 5d is zero. Furthermore, when viewed in the vertical direction, a straight line passing through the center of the signal electrode 5b and parallel to the front-to-back direction also passes through the center of the signal electrode 5d. Therefore, the dead zone D12 is common to both signal electrodes 5b and 5d. Also, when viewed in the vertical direction, a straight line passing through the center of the signal electrode 5c and parallel to the left-to-right direction also passes through the center of the signal electrode 5d. Therefore, the dead zone D22 is common to both signal electrodes 5c and 5d.

[0066] The touch sensor 1 and touch input device 10 allow for a simpler configuration and reduced computational load. More specifically, because the extension direction OD of the PLA is parallel to the left-right or front-back direction, when viewed from below, with reference to the touch position TP, the polarity of the charge generated on the upper main surface US2 located at +45 degrees to the right is made equal to the polarity of the charge generated on the upper main surface US2 located at +45 degrees to the left, and the polarity of the charge generated on the upper main surface US2 located at -45 degrees to the right and -45 degrees to the left is made opposite. Therefore, by arranging multiple signal electrodes at intervals from each other along the left-right and / or front-back directions, multiple touch areas with different charge polarity patterns generated on the multiple signal electrodes can be arranged along the left-right and front-back directions. Because the charge polarity patterns generated on the multiple signal electrodes are different from each other, there is a one-to-one correspondence between the touch area where a touch operation is performed and the charge polarity patterns generated on the multiple signal electrodes.

[0067] Therefore, the touch sensor 1 can detect multiple touch areas using a single piezoelectric film 2. Furthermore, the touch input device 10 can determine the touch area containing the touch position TP based on the polarity of the charges generated on multiple signal electrodes. For determining the touch area containing the touch position TP, details of the magnitude of the charges generated on the multiple signal electrodes are not necessary; only the polarity of the charges generated on the multiple signal electrodes is required.

[0068] In the touch sensor 1, each signal electrode has a dead zone where the charge generated at that electrode is zero. The dead zone of each signal electrode forms the boundary of adjacent touch areas. Therefore, each of the multiple touch areas is clearly separated from each other by the dead zone.

[0069] On the other hand, the multi-directional key switch described in Patent Document 1 (Japanese Patent Publication No. 11-162298) required multiple switches. Therefore, the configuration of the touch sensor 1 is simpler compared to the multi-directional key switch described in Patent Document 1.

[0070] Furthermore, in the touch input device described in Patent Document 2 (International Publication No. 2010 / 143528), the memory unit stores multiple stored voltage patterns, which are predetermined from the voltages generated at each divided electrode, and position information corresponding to those stored voltage patterns. The calculation unit creates a detected voltage pattern from each voltage detected by the detection unit. The calculation unit compares the detected voltage pattern with the stored voltage patterns stored in the memory unit, matches the voltage patterns with a predetermined threshold, and outputs the position information. Therefore, the determination of the touch area including the touch position TP using the touch sensor 1 is simpler and has a lower computational load compared to the calculation of position information in the touch input device described in Patent Document 2.

[0071] Furthermore, the touch input device described in Patent Document 2 does not mention distinguishing the pressing position by region or the dead zone. This is because the touch input device described in Patent Document 2 attempts to specify the pressing position as a single point. On the other hand, the touch sensor 1 and the touch input device 10 attempt to specify the touch position TP as a region. Therefore, the technical concept of the touch sensor 1 and the touch input device 10 differs from the technical concept of the touch input device described in Patent Document 2.

[0072] With the touch sensor 1 and touch input device 10, a multi-directional switch can be realized by specifying the touch position TP in a region. For example, by assigning the numbers 1 to 9 to each of the touch regions A1 to A9, a number input device can be realized.

[0073] Furthermore, in the touch sensor 1 and the touch input device 10, when viewed in the vertical direction, the signal electrodes 5a to 5d are surrounded by the outer edge OS2 of the piezoelectric film 2. As a result, when viewed in the vertical direction, there is a clearance between the signal electrodes 5a to 5d and the outer edge OS2 of the piezoelectric film 2, allowing for the placement of touch areas A1 to A4 and A6 to A9. Also, when viewed in the vertical direction, the shortest distance between the signal electrodes 5a to 5d and the outer edge OS2 of the piezoelectric film 2 is 10% or more of the length of the piezoelectric film 2 along the direction of the shortest distance. This makes it possible to enlarge the touch areas A1 to A4 and A6 to A9.

[0074] Furthermore, the shortest distance between the signal electrodes 5a to 5d and the outer edge OS2 of the piezoelectric film 2 is more preferably 20% or more of the length of the piezoelectric film 2 along the direction of the shortest distance, and even more preferably 30% or more. This makes it possible to enlarge the touch areas A1 to A4 and A6 to A9.

[0075] Figure 7 is a plan view of one modified example of the touch input device 10. As shown in Figure 7, for example, only touch areas A2, A4-A6, and A8 may be set as the touch area. For example, by making it so that the determination unit 111 does not output a determination result when the touch position TP is not included in touch areas A2, A4-A6, and A8, it is possible to set only touch areas A2, A4-A6, and A8 as the touch area. Thus, the arrangement of the touch areas is not necessarily limited to a matrix along the left-right and front-back directions, and any touch area may be set.

[0076] Viewed vertically, touch area A5 is the central touch area AC, which includes the portion located inside the four signal electrodes 5a to 5d. Viewed vertically, touch area A2 is the front touch area AF, located in front of the central touch area AC. Viewed vertically, touch area A4 is the left touch area AL, located to the left of the central touch area AC. Viewed vertically, touch area A6 is the right touch area AR, located to the right of the central touch area AC. Viewed vertically, touch area A8 is the rear touch area AB, located behind the central touch area AC. Therefore, a total of five touch areas can be set: the central touch area AC, the front touch area AF, the left touch area AL, the right touch area AR, and the rear touch area AB. This makes it possible to realize a 5-way switch (e.g., 4 directions: up, down, left, and right + a select switch located in the center). The boundaries between the adjacent central touch area AC, front touch area AF, left touch area AL, right touch area AR, and rear touch area AB are the dead zones D11, D12, D21, and D22.

[0077] Furthermore, in the touch input device 10, the determination circuit 11 considers the output signals S1 to S4 of each signal electrode 5a to 5d to be nonpolar if the absolute value of the output signals S1 to S4 is less than a predetermined threshold. As a result, for example, even if a small charge is generated in the signal electrodes 5b to 5d when a user performs a touch operation on the touch area A1, the determination circuit 11 considers the output signals S2 to S4 of the signal electrodes 5b to 5d to be nonpolar, and can more reliably determine that the touch position TP is included in the touch area A1. Therefore, the determination circuit 11 can more reliably determine the touch area where a touch operation has been performed.

[0078] Furthermore, when a touch operation is performed on touch areas A1, A3, A7, and A9, there is only one signal electrode that generates charge. Therefore, when the touch position TP is included in touch areas A1, A3, A7, and A9, the possibility of misidentifying the touch area due to the generation of a minute charge is higher compared to when the touch position TP is included in touch areas A2, A4 to A6, and A8, where there are two signal electrodes that generate charge. Therefore, this effect is particularly noticeable when a touch operation is performed on touch areas A1, A3, A7, and A9. From the above viewpoint, different predetermined thresholds may be set for touch areas A1, A3, A7, and A9 and touch areas A2, A4 to A6, and A8. This allows the determination circuit 11 to more reliably determine the touch area where a touch operation has been performed.

[0079] [First Modification] The first modification of the present invention, a touch sensor 1a and a touch input device 10a, will be described below with reference to the drawings. Only the parts of the touch sensor 1a and the touch input device 10a that differ from the touch sensor 1 and the touch input device 10 will be described, and the rest will be omitted.

[0080] Figure 8 is a plan view of the touch input device 10a. As shown in Figure 8, the touch sensor 1a is equipped with signal electrodes 5a to 5i. The structures of signal electrodes 5e to 5i are the same as those of signal electrode 5a, so their explanation is omitted. Signal electrodes 5a to 5i are each provided on the upper main surface US2 of the piezoelectric film 2. Therefore, when viewed in the vertical direction, signal electrodes 5a to 5i overlap with the reference electrode 3. Signal electrodes 5a to 5i each function as signal electrodes for outputting the charge generated by the piezoelectric film 2 as output signals S1 to S4. The shapes of signal electrodes 5a to 5i are not limited to those shown in this modified example.

[0081] As shown in Figure 8, the signal electrodes 5a to 5i are arranged with spacing between them along the left-right and front-back directions. In other words, the signal electrodes 5a to 5i are arranged in a 3x3 matrix with spacing between them along the left-right and front-back directions. The output signals from each of the signal electrodes 5a to 5i are input to the determination circuit 11.

[0082] When N and M are integers of 2 or more, it is sufficient that the multiple signal electrodes are arranged in an N x M matrix along the left-right and front-back directions. For example, the multiple signal electrodes may be arranged in a 3 x 2 matrix along the left-right and front-back directions, or in a 2 x 3 matrix.

[0083] The touched member 9 has touch areas A1 to A16 on its upper main surface US9. The boundaries between adjacent touch areas A1 to A16 are dead zones D11, D12, D13, D21, D22, and D23. The touch areas A1 to A16 are arranged in a 4x4 matrix along the left-right and front-back directions. Each of the touch areas A1 to A16 is rectangular. However, each of the touch areas A1 to A16 does not have to be rectangular.

[0084] Furthermore, if multiple signal electrodes are arranged in an N x M matrix along the left-right and front-back directions, the touch area can be arranged in a matrix of up to N+1 x M+1 along the left-right and front-back directions.

[0085] Figure 9 shows an example of the relationship between each touch position and the polarity of the charge generated at each signal electrode in the touch sensor 1a. In Figure 9, 0 indicates no polarity. As shown in Figure 9, when a touch operation is performed on each of the touch areas A1 to A16, the polarity patterns of the charge generated at the signal electrodes 5a to 5i are different, and there is a one-to-one correspondence between the touch area A1 to A16 that is touched and the polarity patterns of the charge generated at the signal electrodes 5a to 5i. Furthermore, when a touch operation is performed on touch areas A2, A3, A5 to A12, A14, and A15, there are two or more signal electrodes that generate charge.

[0086] The memory unit 112 stores, for example, the relationship between each touch position shown in Figure 9 and the polarity of the charge generated at each signal electrode as data.

[0087] First, the determination unit 111 determines the polarity of each output signal of the signal electrodes 5a to 5i based on the respective output signals of the signal electrodes 5a to 5i. Next, the determination unit 111 determines the touch area that includes the touch position TP based on the polarity of each output signal of the signal electrodes 5a to 5i. Furthermore, the determination unit 111 outputs a determination result indicating the touch area that includes the touch position TP.

[0088] The determination unit 111 may consider an output signal to be nonpolar if the absolute value of each output signal of the signal electrodes 5a to 5i is less than a predetermined threshold.

[0089] For example, if the polarities of the output signals of signal electrodes 5a to 5i are in order (negative, 0, 0, 0, 0, 0, 0, 0), the determination unit 111 determines that the touch position TP is included in the touch area A1 and outputs a determination result indicating the touch area A1 in which the touch position TP is included.

[0090] For example, if the polarities of the output signals of signal electrodes 5a to 5i are in order (negative, positive, 0, positive, negative, 0, 0, 0, 0), the determination unit 111 determines that the touch position TP is included in the touch area A6 and outputs a determination result indicating the touch area A6 in which the touch position TP is included.

[0091] Similarly, for touch regions A1 to A16, the determination unit 111 outputs a determination result indicating the touch region that includes the touch position TP, based on the polarity of the respective output signals of the signal electrodes 5a to 5i.

[0092] The determination unit 111 may also determine the touch area containing the touch position TP for each of the four signal electrode output signals based on the polarity of each of the four signal electrodes in a 2x2 grid.

[0093] The touch sensor 1a and the touch input device 10a also produce the same effects as the touch sensor 1 and the touch input device 10, respectively. Furthermore, in the touch sensor 1a, when N and M are integers of 2 or more, multiple signal electrodes are arranged in an N x M matrix along the left-right and front-back directions. This allows the touch area to be arranged in a matrix of up to N+1 x M+1 along the left-right and front-back directions. Therefore, for example, by assigning the numbers 0 to 9 and auxiliary keys to each of the touch areas A1 to A16, a PIN input device and the like can be realized.

[0094] [Second Modification] The following describes the touch sensor 1b and touch input device 10b according to the second modification of the present invention with reference to the drawings. Note that only the parts of the touch sensor 1b and touch input device 10b that differ from the touch sensor 1 and touch input device 10 will be described, and the rest will be omitted.

[0095] Figure 10 is a plan view of the touch input device 10b. As shown in Figure 10, the signal electrodes 5a to 5d are arranged with a gap between them along the left-right direction. In other words, the signal electrodes 5a to 5d are arranged in a 1x4 grid along the left-right direction with a gap between them.

[0096] When M is an integer of 2 or more, it is sufficient that multiple signal electrodes are arranged in a 1x1 matrix along the left-right direction. Alternatively, multiple signal electrodes may be arranged in an Mx1 matrix along the front-back direction.

[0097] The touched member 9 has touch areas A1 to A10 on its upper main surface US9. The boundary between adjacent touch areas A1 to A10 is one of the dead zones D11, D12, D13, D14, and D21. The touch areas A1 to A10 are arranged in a 2x5 matrix along the left-right and front-back directions. Each of the touch areas A1 to A10 is rectangular. However, each of the touch areas A1 to A10 does not have to be rectangular.

[0098] Furthermore, if multiple signal electrodes are arranged in a 1x1 matrix along the left-right direction, the touch area can be arranged in a matrix of up to 2x2 + 1 along the left-right and front-back directions. Also, if multiple signal electrodes are arranged in an Mx1 matrix along the front-back direction, the touch area can be arranged in a matrix of up to M+1x2 along the left-right and front-back directions.

[0099] Figure 11 shows an example of the relationship between each touch position and the polarity of the charge generated at each signal electrode in the touch sensor 1b. In Figure 11, 0 indicates no polarity. As shown in Figure 11, when a touch operation is performed on each of the touch areas A1 to A10, the polarity patterns of the charge generated at the signal electrodes 5a to 5d are different, and there is a one-to-one correspondence between the touch area A1 to A10 that is touched and the polarity patterns of the charge generated at the signal electrodes 5a to 5d. Furthermore, when a touch operation is performed on touch areas A2 to A4 and A7 to A9, there are two or more signal electrodes that generate charge.

[0100] The memory unit 112 stores, for example, the relationship between each touch position shown in Figure 11 and the polarity of the charge generated at each signal electrode as data.

[0101] For example, if the polarities of the output signals S1 to S4 are (negative, 0, 0, 0) in order, the determination unit 111 determines that the touch position TP is included in the touch area A1 and outputs a determination result indicating the touch area A1 in which the touch position TP is included.

[0102] For example, if the polarities of the output signals S1 to S4 are (0, 0, positive, negative) in order, the determination unit 111 determines that the touch position TP is included in the touch area A4 and outputs a determination result indicating the touch area A4 in which the touch position TP is included.

[0103] Similarly, for touch regions A1 to A10, the determination unit 111 outputs a determination result indicating the touch region that includes the touch position TP, based on the polarity of the respective output signals S1 to S4 of the signal electrodes 5a to 5d.

[0104] The determination unit 111 may also determine the touch area containing the touch position TP for each of the four signal electrode output signals based on the polarity of each of the four signal electrodes in a 2x2 grid.

[0105] The touch sensor 1b and the touch input device 10b also produce the same effects as the touch sensor 1 and the touch input device 10, respectively. Furthermore, in the touch sensor 1b, when M is an integer of 2 or more, multiple signal electrodes are arranged in a matrix of 1 row and M columns along the left-right direction, or in a matrix of M rows and 1 column along the front-back direction. This allows the touch area to be arranged in a matrix of up to 2 rows and M+1 columns along the left-right and front-back directions, or in a matrix of up to M+1 rows and 2 columns. Therefore, for example, by assigning the numbers 0 to 9 to each of the touch areas A1 to A10, a PIN input device and the like can be realized.

[0106] [Third Modification] A third modification of the present invention, the touch-type input device 10c, will be described below with reference to the drawings. Only the parts of the touch-type input device 10c that differ from the touch-type input device 10 will be described, and the rest will be omitted.

[0107] Figure 12 is a perspective view of the touched member 9 related to the touch-type input device 10c. As shown in Figure 12, the shape of the touched member 9 related to the touch-type input device 10c is different from the shape of the touched member 9 related to the touch-type input device 10.

[0108] The lower principal surface DS9 is a curved surface that is convex downward (in one direction). In other words, neither concave nor convex surfaces exist within the lower principal surface DS9. However, the lower principal surface DS9 may also be a curved surface that is concave downward (in one direction).

[0109] Figure 13 is a cross-sectional view of the touch input device 10c. As shown in Figure 13, the touch sensor 1 is attached to the touched member 9 such that the piezoelectric film 2 follows the lower main surface DS9 (convex curved surface). If the lower main surface DS9 is a concave curved surface in the downward direction (one direction), it is sufficient that the touch sensor 1 is attached to the touched member 9 such that the piezoelectric film 2 follows the lower main surface DS9 (concave curved surface).

[0110] If the lower main surface DS9 is a curved surface that is convex in one direction, the piezoelectric film 2 will stretch when a touch operation is performed on the upper main surface US9, just as if the lower main surface DS9 were a flat surface. In this case, the deformation direction of the piezoelectric film 2 is the stretching direction. Also, if the lower main surface DS9 is a curved surface that is concave in one direction, the piezoelectric film 2 will compress when a touch operation is performed on the upper main surface US9. In this case, the deformation direction of the piezoelectric film 2 is the compression direction. Therefore, if the lower main surface DS9 is a curved surface that is convex or concave in one direction, the deformation direction of the piezoelectric film 2 when a touch operation is performed on the upper main surface US9 can be kept constant as either the stretching direction or the compression direction. As a result, when viewed from below, with reference to the touch position TP, the polarity of the charge generated on the upper main surface US2 located at +45 degrees to the right can be made equal to the polarity of the charge generated on the upper main surface US2 located at +45 degrees to the left, and the polarity of the charge generated on the upper main surface US2 located at -45 degrees to the right and -45 degrees to the left can be made opposite. As a result, the same effect as the touch input device 10 can be achieved in the touch input device 10c.

[0111] [Fourth Modification] A fourth modification of the present invention, consisting of a touch sensor 1d and a touch input device 10d, will be described below with reference to the drawings. Only the parts of the touch sensor 1d and the touch input device 10d that differ from the touch sensor 1 and the touch input device 10, respectively, will be described, and the rest will be omitted.

[0112] Figure 14 is a plan view of the touch input device 10d. As shown in Figure 14, the shapes of the touch sensor 1d and the touch input device 10d are different from the shapes of the touch sensor 1 and the touch input device 10.

[0113] When viewed in the vertical direction, the touched member 9 and the touch sensor 1d related to the touch input device 10d are circular. More specifically, when viewed in the vertical direction, the piezoelectric film 2 and the reference electrode 3 related to the touch sensor 1d are each circular. However, when viewed in the vertical direction, the touched member 9 and the touch sensor 1d related to the touch input device 10d may be elliptical. Also, when viewed in the vertical direction, the piezoelectric film 2 and the reference electrode 3 related to the touch sensor 1d may each be elliptical. The signal electrodes 5a to 5d are each fan-shaped (the shape of the paper when a fan is opened) when viewed in the vertical direction.

[0114] The touched member 9 has touch areas A1 to A5 on its upper main surface US9. Viewed in the vertical direction, touch area A3 is the central touch area AC, which includes the portion located inside the four signal electrodes 5a to 5d. Viewed in the vertical direction, touch area A1 is the front touch area AF, located in front of the central touch area AC. Viewed in the vertical direction, touch area A2 is the left touch area AL, located to the left of the central touch area AC. Viewed in the vertical direction, touch area A4 is the right touch area AR, located to the right of the central touch area AC. Viewed in the vertical direction, touch area A5 is the rear touch area AB, located behind the central touch area AC.

[0115] Figure 15 shows an example of the relationship between each touch position and the polarity of the charge generated at each signal electrode in the touch sensor 1d. In Figure 15, 0 indicates no polarity. As shown in Figure 15, when a touch operation is performed on each of the touch areas A1 to A5, the polarity patterns of the charge generated at the signal electrodes 5a to 5d are different, and there is a one-to-one correspondence between the touch area A1 to A5 that is touched and the polarity patterns of the charge generated at the signal electrodes 5a to 5d. In addition, when a touch operation is performed on touch areas A1 to A5, there are two or more signal electrodes that generate charge.

[0116] The memory unit 112 stores, for example, the relationship between each touch position shown in Figure 16 and the polarity of the charge generated at each signal electrode as data.

[0117] For example, if the polarities of the output signals S1 to S4 are (positive, negative, 0, 0) in order, the determination unit 111 determines that the touch position TP is included in the touch area A1 and outputs a determination result indicating the touch area A1 in which the touch position TP is included.

[0118] For example, if the polarities of the output signals S1 to S4 are in order (negative, positive, positive, negative), the determination unit 111 determines that the touch position TP is included in the touch area A3 and outputs a determination result indicating the touch area A3 in which the touch position TP is included.

[0119] Similarly, for touch regions A1 to A5, the determination unit 111 outputs a determination result indicating the touch region that includes the touch position TP, based on the polarity of the respective output signals S1 to S4 of the signal electrodes 5a to 5d.

[0120] The touch sensor 1d and the touch input device 10d also provide the same effects as the touch sensor 1 and the touch input device 10, respectively.

[0121] [Fifth Modification] The following describes the fifth modification of the present invention, specifically the touch sensor 1e and the touch input device 10e, with reference to the drawings. Only the parts of the touch sensor 1e and the touch input device 10e that differ from the touch sensor 1 and the touch input device 10, respectively, will be described, and the rest will be omitted.

[0122] Figure 16 is a block diagram of the touch input device 10e. As shown in Figure 16, the touch sensor 1e outputs output signals S1 to S8 in response to the user's touch operation. The output signals S1 to S8 are input to the determination circuit 11.

[0123] Figure 17 is a plan view of the touch input device 10e. As shown in Figure 17, the touch sensor 1e further comprises outer peripheral electrodes 12a to 12d. Each of the outer peripheral electrodes 12a to 12d is conductive. The material of each of the outer peripheral electrodes 12a to 12d is, for example, copper. Each of the outer peripheral electrodes 12a to 12d is rectangular in shape, having a front and rear edge extending in the left and right directions, and a left and right edge extending in the front and back directions when viewed in the vertical direction. Each of the outer peripheral electrodes 12a to 12d is provided on the upper main surface US2 of the piezoelectric film 2, similar to the signal electrodes 5a to 5d. Therefore, each of the outer peripheral electrodes 12a to 12d overlaps with the reference electrode 3 when viewed in the vertical direction. Each of the outer peripheral electrodes 12a to 12d functions as a signal electrode for outputting the charge generated by the piezoelectric film 2 as output signals S5 to S8. Note that the shape of the outer peripheral electrodes 12a to 12d is not limited to the shape shown in this modified example.

[0124] Each outer electrode, like the signal electrodes 5a to 5d, has a dead zone where the charge generated on that electrode is zero. The dead zone is the boundary between charge-generating regions on each outer electrode and in the vicinity of each outer electrode when viewed in the vertical direction. The principle of dead zone generation for each outer electrode is the same as that for the dead zones of the signal electrodes 5a to 5d, so an explanation is omitted.

[0125] The outer electrode 12a is positioned in front of the signal electrodes 5a to 5d. The outer electrode 12a is positioned such that its center lies on the dead zone D11. The outer electrode 12a has dead zones DO1 and D11. Dead zone DO1 is a straight line passing through the center of the outer electrode 12a and parallel to the left-right direction. Dead zone D11 is a straight line passing through the center of the outer electrode 12a and parallel to the front-back direction. The dead zone D11 of the outer electrode 12a is common to the dead zone D11 of the signal electrodes 5a and 5c. The outer electrode 12a corresponds to the first outer electrode according to the present invention.

[0126] The outer electrode 12b is positioned to the right of the signal electrodes 5a to 5d. The outer electrode 12b is positioned such that its center lies on the dead zone D21. The outer electrode 12b has dead zones DO2 and D21. The dead zone DO2 is a straight line passing through the center of the outer electrode 12b and parallel to the front-to-back direction. The dead zone D21 is a straight line passing through the center of the outer electrode 12b and parallel to the left-to-right direction. The dead zone D21 of the outer electrode 12b is common to the dead zone D21 of the signal electrodes 5a and 5b. The outer electrode 12b corresponds to the second outer electrode according to the present invention.

[0127] The outer electrode 12c is positioned to the left of the signal electrodes 5a to 5d. The outer electrode 12c is positioned such that its center lies on the dead zone D22. The outer electrode 12c has dead zones DO3 and D22. Dead zone DO3 is a straight line passing through the center of the outer electrode 12c and parallel to the front-to-back direction. Dead zone D22 is a straight line passing through the center of the outer electrode 12c and parallel to the left-to-right direction. The dead zone D22 of the outer electrode 12c is common to the dead zone D22 of the signal electrodes 5c and 5d. The outer electrode 12c corresponds to the third outer electrode according to the present invention.

[0128] The outer electrode 12d is positioned after the signal electrodes 5a to 5d. The outer electrode 12d is positioned such that its center lies on the dead zone D12. The outer electrode 12d has dead zones DO4 and D12. Dead zone DO4 is a straight line passing through the center of the outer electrode 12d and parallel to the left-right direction. Dead zone D12 is a straight line passing through the center of the outer electrode 12d and parallel to the front-back direction. The dead zone D12 of the outer electrode 12d is common to the dead zone D12 of the signal electrodes 5b and 5d. The outer electrode 12d corresponds to the fourth outer electrode according to the present invention.

[0129] Touch area A1 is the area enclosed by dead zones D11, D21, DO1, and DO3 when viewed in the vertical direction. Touch area A2 is the area enclosed by dead zones D11, D12, D21, and DO1 when viewed in the vertical direction. Touch area A3 is the area enclosed by dead zones D12, D21, DO1, and DO4 when viewed in the vertical direction. Touch area A4 is the area enclosed by dead zones D11, D21, DO1, and DO3 when viewed in the vertical direction. Touch area A6 is the area enclosed by dead zones D12, D21, D22, and DO2 when viewed in the vertical direction. Touch area A7 is the area enclosed by dead zones D11, D22, DO3, and DO4 when viewed in the vertical direction. Touch area A8 is the area enclosed by dead zones D11, D12, D22, and DO4 when viewed in the vertical direction. Touch area A9 is the region surrounded by dead zones D12, D22, DO2, and DO4 when viewed in the vertical direction.

[0130] Figure 18 shows an example of the relationship between each touch position and the polarity of the charge generated on each signal electrode and each outer electrode. Note that Figure 18 shows cases where deformation occurs not only near the touch position TP, but also at locations away from the touch position TP, when the user presses each touch area.

[0131] As shown in Figure 18, when a user presses each of the touch areas A1 to A9, the polarity patterns of the charges generated on the signal electrodes 5a to 5d and the outer peripheral electrodes 12a to 12d are different, and there is a one-to-one correspondence between the pressed touch areas A1 to A9 and the polarity patterns of the charges generated on the signal electrodes 5a to 5d and the outer peripheral electrodes 12a to 12d.

[0132] Figure 19 shows an example of the relationship between each touch position and the polarity of the charge generated on each signal electrode and each outer electrode. Figure 18 shows a case where, when the user lifts their finger or pen from each touch area, deformation occurs not only near the touch position TP but also at locations away from the touch position TP.

[0133] As shown in Figure 19, for each of the touch areas A1 to A9, when the user lifts their finger or pen from each touch area, the polarity patterns of the charge generated on the signal electrodes 5a to 5d and the outer peripheral electrodes 12a to 12d are different, and there is a one-to-one correspondence between the touch areas A1 to A9 from which the finger or pen has been lifted and the polarity patterns of the charge generated on the signal electrodes 5a to 5d and the outer peripheral electrodes 12a to 12d.

[0134] As shown in Figures 18 and 19, there is a one-to-one correspondence between the touch areas A1 to A9 where a touch operation was performed (pressed or released from a finger or pen, etc.) and the polarity patterns of the charges generated on the signal electrodes 5a to 5d and the outer peripheral electrodes 12a to 12d. That is, from the polarity patterns of the charges generated on the signal electrodes 5a to 5d and the outer peripheral electrodes 12a to 12d, it is possible to determine which touch area was pressed and which touch area the finger or pen, etc. was released from.

[0135] Furthermore, the polarity pattern of the charge generated on the signal electrodes 5a to 5d and the outer peripheral electrodes 12a to 12d when a touch operation is performed on touch areas A1 to A9 (pressed or released by a finger or pen, etc.) is different from the polarity pattern of the charge generated on the signal electrodes 5a to 5d and the outer peripheral electrodes 12a to 12d when a touch operation is performed on areas other than touch areas A1 to A9 (for example, the area surrounded by the left and front edges of the piezoelectric film 2, and the dead zones DO1 and DO3 when viewed in the vertical direction). This allows the determination circuit 11 to more reliably determine which touch area has been touched.

[0136] More specifically, the determination unit 111 determines the polarity of each output signal S1 to S8 based on the respective output signals S1 to S4 of the signal electrodes 5a to 5d and the respective output signals S5 to S8 of the outer peripheral electrodes 12a to 12d. Next, the determination unit 111 determines the touch area that includes the touch position TP based on the polarity of each output signal S1 to S8. Furthermore, the determination unit 111 outputs a determination result indicating the touch area that includes the touch position TP.

[0137] The touch sensor 1e and the touch input device 10e achieve the same effects as the touch sensor 1 and the touch input device 10, respectively. Furthermore, with the touch sensor 1e and the touch input device 10e, even when a touch operation is performed (pressed or lifted by a finger or pen, etc.), deformation occurs not only near the touch position TP but also in areas away from the touch position TP, it is possible to determine which touch area was pressed and from which touch area the finger or pen, etc. was lifted. Therefore, a rigid material that deforms over a wide area can be used as the touched member 9. In addition, the distance between the signal electrodes 5a to 5d can be shortened. Consequently, the touch sensor can be miniaturized. As a result, the design flexibility of the touch sensor and the touch input device can be improved.

[0138] Figure 20 is a plan view of one modified example of the touch input device 10e. As shown in Figure 20, the outer electrode 12c may be arranged such that its center lies on the dead zone D21. In this case, the outer electrode 12c has dead zones DO3 and D21. The dead zone D21 is a straight line passing through the center of the outer electrode 12c and parallel to the left-right direction. The dead zone D21 of the outer electrode 12c is common to the dead zone D21 of the signal electrodes 5a and 5b.

[0139] Similarly, the outer electrode 12a may be positioned such that its center lies on the dead zone D12. In this case, the outer electrode 12a has dead zones DO1 and D12. The dead zone D12 is a straight line passing through the center of the outer electrode 12a and parallel to the front-to-back direction. The dead zone D12 of the outer electrode 12a is common to the dead zone D12 of the signal electrodes 5b and 5d.

[0140] Similarly, the outer electrode 12b may be positioned such that its center lies on the dead zone D22. In this case, the outer electrode 12b has dead zones DO2 and D22. The dead zone D22 is a straight line passing through the center of the outer electrode 12b and parallel to the left-right direction. The dead zone D22 of the outer electrode 12b is common to the dead zone D22 of the signal electrodes 5c and 5d.

[0141] Similarly, the outer electrode 12d may be positioned such that its center lies on the dead zone D11. In this case, the outer electrode 12d has dead zones DO4 and D11. The dead zone D11 is a straight line passing through the center of the outer electrode 12d and parallel to the front-to-back direction. The dead zone D11 of the outer electrode 12d is common to the dead zone D11 of the signal electrodes 5a and 5c.

[0142] Figure 21 is a plan view of one modified example of the touch-type input device 10e. As shown in Figure 21, the shapes of the outer peripheral electrodes 12a to 12d do not have to be the same.

[0143] Figure 22 shows the signal electrode and outer electrode necessary for determining the touch position TP. When the rigidity of the touched member 9 is low, it is conceivable that only the vicinity of the touch position TP will deform significantly, while areas far from the touch position TP will not deform much. In this case, it is conceivable that the output signal of the electrode far from the touch position TP will become small, making it impossible to determine the polarity of the output signal.

[0144] In Figure 22, "*1" indicates the signal electrode and / or outer electrode necessary for determining the touch position TP. "*2" indicates a signal electrode that can determine the touch position TP if the polarity of at least three of the four signal electrodes can be determined. "*3" indicates a signal electrode that can determine the touch position TP if the polarity of at least two of the three signal electrodes can be determined. The blank spaces in Figure 22 represent signal electrodes and / or outer electrodes that do not require polarity determination.

[0145] For example, if the touch position TP is included in the touch area A1, the touch position TP can be determined by satisfying the following conditions: the polarity of the output signal of the outer peripheral electrode 12a is negative, the polarity of the output signal of the outer peripheral electrode 12c is negative, and the polarity of the output signals of at least two of the signal electrodes 5a to 5c is positive.

[0146] For example, if the touch position TP is included in the touch area A2, the touch position TP can be determined by satisfying three conditions: the polarity of the output signal of signal electrode 5a is negative, the polarity of the output signal of signal electrode 5b is positive, and the polarity of the output signal of outer peripheral electrode 12a is positive.

[0147] For example, if the touch position TP is included in the touch area A5, to determine the touch position TP, it is sufficient to satisfy at least three of the following four conditions: the polarity of the output signal of signal electrode 5a is positive, the polarity of the output signal of signal electrode 5b is negative, the polarity of the output signal of signal electrode 5c is negative, and the polarity of the output signal of signal electrode 5d is positive.

[0148] With the touch sensor 1e and touch input device 10e, even if only the vicinity of the touch position TP deforms significantly and areas away from the touch position TP do not deform much, it is possible to determine which touch area was pressed and which touch area the finger or pen was lifted from.

[0149] [Other Embodiments] The touch sensor according to the present invention is not limited to touch sensors 1, 1a, 1b, 1d, and 1e, but can be modified within the scope of its gist. Furthermore, the structures of touch sensors 1, 1a, 1b, 1d, and 1e may be combined in any way.

[0150] The touch input device according to the present invention is not limited to touch input devices 10, 10a to 10e, but can be modified within the scope of its gist. Furthermore, the structures of the touch input devices 10, 10a to 10e may be combined in any way.

[0151] As an example, the structures of touch sensors 1a and 1e may be combined. Similarly, the structures of touch input devices 10a and 10e may be combined. Figure 23 is a plan view of a touch input device 10f that combines the structures of touch input devices 10a and 10e. As shown in Figure 23, the touch sensor 1f further comprises outer peripheral electrodes 12a to 12d. Figure 23 shows an example where the dead zone D12 of the outer peripheral electrode 12a is common with the dead zone D12 of the signal electrodes 5b, 5e, and 5h. However, the outer peripheral electrode 12a may be arranged so that its dead zone is common with the dead zone D11 of the signal electrodes 5a, 5d, and 5g, or the outer peripheral electrode 12a may be arranged so that its dead zone is common with the dead zone D13 of the signal electrodes 5c, 5f, and 5i.

[0152] Similarly, Figure 23 shows an example where the dead zone D22 of the outer electrode 12b is common to the dead zone D22 of the signal electrodes 5d, 5e, and 5f. However, the outer electrode 12b may be arranged so that its dead zone is common to the dead zone D21 of the signal electrodes 5a, 5b, and 5c, or it may be arranged so that its dead zone is common to the dead zone D23 of the signal electrodes 5g, 5h, and 5i.

[0153] Similarly, Figure 23 shows an example where the dead zone D22 of the outer electrode 12c is common to the dead zone D22 of the signal electrodes 5d, 5e, and 5f. However, the outer electrode 12c may be arranged such that the dead zone of the outer electrode 12c is common to the dead zone D21 of the signal electrodes 5a, 5b, and 5c, or the outer electrode 12c may be arranged such that the dead zone of the outer electrode 12b is common to the dead zone D23 of the signal electrodes 5g, 5h, and 5i.

[0154] Similarly, Figure 23 shows an example where the dead zone D12 of the outer peripheral electrode 12d is common to the dead zone D12 of the signal electrodes 5b, 5e, and 5h. However, the outer peripheral electrode 12d may be arranged such that its dead zone is common to the dead zone D11 of the signal electrodes 5a, 5d, and 5g, or the outer peripheral electrode 12d may be arranged such that its dead zone is common to the dead zone D13 of the signal electrodes 5c, 5f, and 5i.

[0155] As an example, the structures of touch sensors 1b and 1e may be combined. Similarly, the structures of touch input devices 10b and 10e may be combined. Figure 24 is a plan view of a touch input device 10g that combines the structures of touch input devices 10b and 10e. As shown in Figure 24, the touch sensor 1g further comprises outer peripheral electrodes 12a to 12d. Figure 24 shows an example where the dead zone D12 of the outer peripheral electrode 12a is common with the dead zone D12 of the signal electrode 5b, but the outer peripheral electrode 12a may be arranged so that the dead zone of the outer peripheral electrode 12a is common with the dead zone D11 of the signal electrode 5a, or so that the dead zone of the outer peripheral electrode 12a is common with the dead zone D13 of the signal electrode 5c, or so that the dead zone of the outer peripheral electrode 12a is common with the dead zone D14 of the signal electrode 5d.

[0156] Similarly, Figure 24 shows an example where the dead zone D12 of the outer peripheral electrode 12d is common to the dead zone D12 of the signal electrode 5b. However, the outer peripheral electrode 12d may be arranged such that its dead zone is common to the dead zone D11 of the signal electrode 5a, or so that its dead zone is common to the dead zone D13 of the signal electrode 5c, or so that its dead zone is common to the dead zone D14 of the signal electrode 5d.

[0157] Note that if the touch area is a single row, the number of outer peripheral electrodes may be three. Figure 25 is a plan view showing the arrangement of outer peripheral electrodes when the touch area is a single row. As shown in Figure 25, when the touch area is a single row, the outer peripheral electrode 12a is not required. The touch sensor only needs to have either the outer peripheral electrode 12a or 12d.

[0158] The present invention has the following configuration.

[0159] (1) A touch sensor comprising: a piezoelectric film having a first main surface and a second main surface arranged in the vertical direction; a plurality of signal electrodes provided on the first main surface; and a reference electrode provided on the second main surface, which overlaps with each of the plurality of signal electrodes when viewed in the vertical direction, wherein the piezoelectric film includes a piezoelectric body stretched in the stretching direction, the signal electrodes have a dead zone where the charge generated on the signal electrodes is zero, the plurality of signal electrodes are spaced apart from each other along the left-right direction perpendicular to the vertical direction and / or the front-back direction perpendicular to the vertical direction and the left-right direction, and the stretching direction is parallel to the left-right direction or the front-back direction.

[0160] (2) The touch sensor according to (1), wherein N and M are each integers of 2 or more, and the plurality of signal electrodes are arranged in a matrix of N rows and M columns along the left-right direction and the front-back direction.

[0161] (3) The touch sensor described in (2), wherein N and M are each 2.

[0162] (4) The touch sensor according to (1), wherein M is an integer of 2 or more, and the plurality of signal electrodes are arranged in a matrix of 1 row and M columns along the left-right direction, or in a matrix of M rows and 1 column along the front-back direction.

[0163] (5) The touch sensor according to any one of (1) to (4), wherein, when viewed in the vertical direction, the plurality of signal electrodes are surrounded by the outer edge of the piezoelectric film, and when viewed in the vertical direction, the shortest distance between the signal electrodes and the outer edge of the piezoelectric film is 10% or more of the length of the piezoelectric film along the direction of the shortest distance.

[0164] (6) A touch input device comprising: a touch sensor as described in any of (1) to (5); and a touched member having a curved surface that is convex or concave in one direction, wherein the touch sensor is attached to the touched member such that the piezoelectric film follows the curved surface.

[0165] (7) A touch input device comprising: a touch sensor as described in any of (1) to (5); and a determination circuit to which the output signals of each of the plurality of signal electrodes are input, wherein the determination circuit outputs a determination result indicating a touch area that includes a touch position based on the polarity of the output signals of each of the plurality of signal electrodes, and the boundary between adjacent touch areas is the dead zone.

[0166] (8) A touch input device comprising: a touch sensor as described in (2) or (3); and a determination circuit to which the output signals of each of the plurality of signal electrodes are input, wherein the determination circuit outputs a determination result indicating a touch area that includes a touch position based on the polarity of the output signals of each of the plurality of signal electrodes, the touch areas are arranged in a matrix of up to N+1 rows and M+1 columns along the left-right and front-back directions, and the boundaries of adjacent touch areas are the dead zones.

[0167] (9) A touch input device comprising: a touch sensor as described in (3); and a determination circuit to which the output signals of each of the four signal electrodes are input, wherein the determination circuit outputs a determination result indicating a touch area that includes a touch position based on the polarity of the output signals of each of the four signal electrodes, and the touch area consists of a total of five parts: a central touch area including the part located inside the four signal electrodes when viewed in the vertical direction, a front touch area located in front of the central touch area, a back touch area located behind the central touch area, a left touch area located to the left of the central touch area, and a right touch area located to the right of the central touch area, and the boundary between adjacent touch areas is the dead zone.

[0168] (10) A touch input device comprising: a touch sensor as described in (3); and a determination circuit to which the output signals of each of the four signal electrodes are input, wherein the determination circuit outputs a determination result indicating a touch area that includes a touch position based on the polarity of the output signals of each of the four signal electrodes, the touch areas are arranged in a 3x3 matrix along the left-right and front-back directions, and the boundaries of adjacent touch areas are the dead zones.

[0169] (11) The touch input device according to (10), wherein, with respect to the output signal of each of the four signal electrodes, the determination circuit considers the output signal to be nonpolar if the absolute value of the output signal is less than a predetermined threshold.

[0170] (12) A touch input device comprising: a touch sensor as described in (4); and a determination circuit to which the output signals of each of the plurality of signal electrodes are input, wherein the determination circuit outputs a determination result indicating a touch area that includes a touch position based on the polarity of the output signals of each of the plurality of signal electrodes, the touch areas are arranged in a matrix of up to 2 rows and M+1 columns or up to M+1 rows and 2 columns along the left-right direction and the front-back direction, and the boundaries of adjacent touch areas are the dead zones.

[0171] 1, 1a, 1b, 1d, 1e, 1f, 1g: Touch sensor 2: Piezoelectric film 3: Reference electrode 4, 8: Coverlay 5a to 5i: Signal electrode 6: Substrate 7: Shielding member 9: Touched member 10, 10a to 10g: Touch input device 11: Judgment circuit 12a to 12d: Outer edge electrode 111: Judgment unit 112: Memory unit A1 to A16: Touch area AB: Rear touch area AC: Center touch area AF: Front touch area AL: Left touch area AR: Right touch area D11, D12, D13, D14, D21, D22, D23, DO1 to DO4: Dead zone DS2, DS9: Lower main surface Lmin1, Lmin2, Lmin3, Lmin4: Distance OD: Stretching direction OS2: Outer edge S1-S4: Output signal TP: Touch position US2, US9: Upper main surface

Claims

1. A touch sensor comprising: a piezoelectric film having a first main surface and a second main surface arranged in the vertical direction; a plurality of signal electrodes provided on the first main surface; and a reference electrode provided on the second main surface, which overlaps with each of the plurality of signal electrodes when viewed in the vertical direction, wherein the piezoelectric film includes a piezoelectric body stretched in the stretching direction; the signal electrodes have a dead zone where the charge generated on the signal electrodes is zero; the plurality of signal electrodes are spaced apart from each other along the left-right direction perpendicular to the vertical direction, and / or the front-back direction perpendicular to the vertical direction and the left-right direction; and the stretching direction is parallel to the left-right direction or the front-back direction.

2. The touch sensor according to claim 1, wherein N and M are each integers of 2 or more, and the plurality of signal electrodes are arranged in a matrix of N rows and M columns along the left-right direction and the front-back direction.

3. The touch sensor according to claim 2, wherein N and M are each 2.

4. The touch sensor according to claim 1, wherein M is an integer of 2 or more, and the plurality of signal electrodes are arranged in a matrix of 1 row and M columns along the left-right direction, or in a matrix of M rows and 1 column along the front-back direction.

5. The touch sensor according to any one of claims 2 to 4, further comprising four outer peripheral electrodes provided on the first main surface and overlapping with the reference electrode when viewed in the vertical direction, wherein each outer peripheral electrode has a dead zone where the charge generated on the outer peripheral electrode is zero, a portion of the dead zone of the outer peripheral electrode coincides with a portion of the dead zone of any of the plurality of signal electrodes, and the four outer peripheral electrodes include: a first outer peripheral electrode positioned in front of the plurality of signal electrodes; a second outer peripheral electrode positioned to the right of the plurality of signal electrodes; a third outer peripheral electrode positioned to the left of the plurality of signal electrodes; and a fourth outer peripheral electrode positioned behind the plurality of signal electrodes.

6. The touch sensor according to claim 4, further comprising three outer peripheral electrodes provided on the first main surface and overlapping with the reference electrode when viewed in the vertical direction, wherein each outer peripheral electrode has a dead zone where the charge generated on the outer peripheral electrode is zero, a portion of the dead zone of the outer peripheral electrode coincides with a portion of the dead zone of any of the plurality of signal electrodes, and when the plurality of signal electrodes are arranged in a matrix of 1 row and M columns along the left-right direction, the three outer peripheral electrodes include: a second outer peripheral electrode positioned to the left of the plurality of signal electrodes, a third outer peripheral electrode positioned to the right of the plurality of signal electrodes, and a fourth outer peripheral electrode positioned in front of or behind the plurality of signal electrodes.

7. The touch sensor according to any one of claims 1 to 6, wherein, when viewed in the vertical direction, the plurality of signal electrodes are surrounded by the outer edge of the piezoelectric film, and when viewed in the vertical direction, the shortest distance between the signal electrodes and the outer edge of the piezoelectric film is 10% or more of the length of the piezoelectric film along the direction of the shortest distance.

8. A touch input device comprising: a touch sensor according to any one of claims 1 to 7; and a touch-receiving member having a curved surface that is convex or concave in one direction, wherein the touch sensor is attached to the touch-receiving member such that the piezoelectric film follows the curved surface.

9. A touch input device comprising: a touch sensor according to any one of claims 1 to 7; and a determination circuit that receives the output signals of each of the plurality of signal electrodes, wherein the determination circuit outputs a determination result indicating a touch area that includes a touch position based on the polarity of the output signals of each of the plurality of signal electrodes, and the boundary of adjacent touch areas is the dead zone of the signal electrode.

10. A touch input device comprising: a touch sensor according to claim 2 or claim 3; and a determination circuit that receives the output signals of each of the plurality of signal electrodes, wherein the determination circuit outputs a determination result indicating a touch area that includes a touch position based on the polarity of the output signals of each of the plurality of signal electrodes; the touch areas are arranged in a matrix of up to N+1 rows and M+1 columns along the left-right and front-back directions; and the boundaries of adjacent touch areas are the dead zones.

11. A touch input device comprising: a touch sensor as described in claim 3; and a determination circuit to which the output signals of each of the four signal electrodes are input, wherein the determination circuit outputs a determination result indicating a touch area that includes a touch position based on the polarity of the output signals of each of the four signal electrodes, and the touch area consists of a total of five touch areas: a central touch area including the portion located inside the four signal electrodes when viewed in the vertical direction, a front touch area located in front of the central touch area, a back touch area located behind the central touch area, a left touch area located to the left of the central touch area, and a right touch area located to the right of the central touch area, and the boundary between adjacent touch areas is the dead zone.

12. A touch input device comprising: a touch sensor as described in claim 3; and a determination circuit to which the output signals of each of the four signal electrodes are input, wherein the determination circuit outputs a determination result indicating a touch area that includes a touch position based on the polarity of the output signals of each of the four signal electrodes, the touch areas are arranged in a 3x3 matrix along the left-right and front-back directions, and the boundaries of adjacent touch areas are the dead zones.

13. With respect to the output signals of each of the four signal electrodes, the determination circuit considers the output signal to be nonpolar if the absolute value of the output signal is less than a predetermined threshold, as described in claim 12.

14. A touch input device comprising: a touch sensor as described in claim 4; and a determination circuit to which the output signals of each of the plurality of signal electrodes are input, wherein the determination circuit outputs a determination result indicating a touch area that includes a touch position based on the polarity of the output signals of each of the plurality of signal electrodes; the touch areas are arranged in a matrix of up to 2 rows and M+1 columns, or up to M+1 rows and 2 columns, along the left-right direction and the front-back direction; and the boundaries of adjacent touch areas are the dead zones.

15. A touch input device comprising: a touch sensor according to claim 5 or claim 6; and a determination circuit that receives the output signals of each of the plurality of signal electrodes and the output signals of each of the outer peripheral electrodes, wherein the determination circuit outputs a determination result indicating a touch area that includes a touch position based on the polarity of the output signals of each of the plurality of signal electrodes and the polarity of the output signals of each of the outer peripheral electrodes, and the boundary of adjacent touch areas is the dead zone of the signal electrode.

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