Input device and display device

Abstract

To detect a touch position and pressure with high sensitivity at substantially the same time.SOLUTION: An input device includes a touch sensor and a control unit. The touch sensor includes: a piezoelectric film; a first detection conductor facing the piezoelectric film and including a plurality of first electrodes arranged linearly along a first straight line and a plurality of second electrodes arranged linearly along a second straight line, the first and second electrodes being electrically insulated from each other; and a second detection conductor facing the first detection conductor and arranged on the opposite side of the first detection conductor across the piezoelectric film. The control unit is configured to separate signals detected from the first detection conductor, with the second detection conductor as a reference potential, into first signals of a commercial power supply frequency band and second signals of a frequency band other than the commercial power supply frequency band, detect a touch position using the first signals, and detect pressure using the second signals.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an input device and a display device. [Background technology]

[0002] Conventionally, various touch-type input devices have been proposed that detect operation input by touching an operation surface. As such touch-type input devices, a three-dimensional (3D) touch sensor (a touch sensor that detects position (2D) and pressure (1D)) that detects position and pressure has been proposed.

[0003] For example, Patent Document 1 discloses a touch panel formed by stacking a piezoelectric sensor and a position detection sensor. The piezoelectric sensor and the position detection sensor are connected to a pressure detection circuit and a touch position detection circuit, respectively. Here, if a capacitive position detection sensor is used as the position detection sensor, the touch position can be detected by a change in capacitance, so that the touch position can be detected by just lightly touching the operation surface. However, as disclosed in Patent Document 1, a system that uses separate electronic devices to sense pressure (pressure) changes and capacitance changes has the problem that the touch panel becomes larger and more expensive.

[0004] One solution to address these issues would be to use common electronics to sense both pressure changes and capacitance changes.

[0005] For example, Patent Document 2 discloses a thin touch-type input device that forms a laminate in which a piezoelectric film is sandwiched between a first detection conductor and a second detection conductor, and performs both pressure detection and touch position detection (capacitive type) using detection signals output via the first detection conductor and the second detection conductor. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2015 / 046289 [Patent Document 2] International Publication No. 2014 / 192786 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the touch input device disclosed in Patent Document 2 needs to switch between pressure detection and touch position detection, and the polarization of the piezoelectric film caused by the pressure is alleviated during touch position detection, which may reduce the detection sensitivity of pressure. In addition, in the touch input device disclosed in Patent Document 2, pressure detection and touch position detection are not performed simultaneously, and an example of an interval of switching between pressure detection and touch position detection is 10 milliseconds (100 Hz). Here, to detect a pressure caused by a single contact with a finger, the contact usually continues for 100 milliseconds or more. Therefore, in the touch input device disclosed in Patent Document 2, which can only detect intermittently for a period of 100 milliseconds or more, there is a risk that the detection accuracy of pressure may decrease.

[0008] In view of the above, an object of the present invention is to provide a technique capable of detecting a touch position and a pressure substantially simultaneously with high sensitivity. [Means for solving the problem]

[0009] An input device according to one embodiment of the present invention includes a touch sensor and a control unit, wherein the touch sensor has a piezoelectric film, a plurality of first electrodes facing the piezoelectric film and arranged linearly along a first straight line, and a plurality of second electrodes arranged linearly along a second straight line, the first detection conductor including the plurality of first electrodes and the plurality of second electrodes being electrically insulated from each other, and a second detection conductor facing the first detection conductor and arranged on the opposite side of the piezoelectric film from the first detection conductor, and the control unit separates a signal detected from the first detection conductor using the second detection conductor as a reference potential into a first signal in a commercial power frequency band and a second signal in a frequency band other than the commercial power frequency band, detects a touch position using the first signal, and detects a pressure using the second signal. Effect of the Invention

[0010] According to one aspect of the present invention, it is possible to detect the touch position and pressure substantially simultaneously with high sensitivity. [Brief description of the drawings]

[0011] [Figure 1] 1 is an external perspective view of an exemplary display device according to a first embodiment of the present invention; [Figure 2A] 1 is a side cross-sectional view of an exemplary display device according to a first embodiment; [Figure 2B] FIG. 1 is a diagram showing an example of the configuration of an exemplary first detection conductor according to a first embodiment; [Figure 2C] FIG. 1 illustrates an exemplary row electrode according to a first embodiment. [Figure 2D] FIG. 1 illustrates an exemplary column electrode according to a first embodiment. [Figure 2E] FIG. 1 shows exemplary row and column electrodes according to a first embodiment; [Diagram 3] FIG. 1 is an explanatory diagram for explaining a configuration of an exemplary display device according to a first embodiment; [Figure 4] FIG. 1 is an explanatory diagram for explaining an example of processing of a signal processing unit of an exemplary display device according to a first embodiment; [Diagram 5]FIG. 1 is a diagram showing an example of a filter frequency characteristic of a filter used by a signal processing unit of an exemplary display device according to the first embodiment and its modified example to extract a piezoelectric signal; [Figure 6] FIG. 11 is an explanatory diagram for explaining an example of processing of a signal processing unit of an exemplary display device according to a modified example of the first embodiment; [Figure 7] FIG. 1 is a diagram showing an example of a filter frequency characteristic of a filter used to extract a signal of a commercial power frequency band component in an exemplary display device according to the first embodiment and its modified example; [Figure 8A] FIG. 13 is a diagram showing an example of the configuration of an exemplary first detection conductor according to a second embodiment of the present invention; [Figure 8B] FIG. 13 shows exemplary row and column electrodes according to a second embodiment. [Figure 8C] FIG. 13 is a side cross-sectional view of an exemplary first detection conductor according to a second embodiment; [Figure 9] FIG. 13 is a diagram showing an example of the configuration of an exemplary first detection conductor according to a third embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] (How the present invention was arrived at) When a finger is brought close to the detection electrode of a piezoelectric sensor while pressure is being detected using the piezoelectric sensor, a noise component dependent on the commercial power supply frequency (commonly known as hum or humming noise) is observed in the signal from the detection electrode.

[0013] Here, the commercial power frequency refers to the frequency of the AC power supplied as a commercial power source. The commercial power frequency may vary depending on the country or region; for example, the commercial power frequency in Japan is 50 Hz or 60 Hz. Noise components that depend on the commercial power frequency (hum noise) may be called commercial power frequency noise, commercial power frequency dependent noise, etc.

[0014] Generally, this noise component is not used for pressure detection, and is therefore removed by a band cut filter or the like. However, as a result of extensive research, the present inventor has found that this noise component can be used to detect the presence or absence of a touch by a finger by separating it. Therefore, hereinafter, an embodiment for detecting a touch position and pressure by using commercial power frequency noise will be described.

[0015] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate. However, more detailed description than necessary may be omitted. For example, detailed description of already well-known matters or duplicate description of substantially the same configuration may be omitted. This is to avoid the following description becoming unnecessarily redundant and to facilitate understanding by those skilled in the art.

[0016] The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present invention, and are not intended to limit the subject matter described in the claims. In addition, elements shown in the various drawings are not necessarily drawn to scale.

[0017] (First embodiment) 1 is a perspective view of the appearance of a display device according to a first embodiment of the present invention. Examples of such a display device include various devices such as mobile PCs (Personal Computers) having a touch detection function, tablet terminals, smartphones, and digital cameras.

[0018] As shown in FIG. 1, the display device 1 includes a housing 10 having a substantially rectangular parallelepiped shape. The front side (positive side in the Z direction) of the housing 10 is open. In this specification and drawings, the width direction (horizontal direction) of the housing 10 is defined as the X direction, the length direction (vertical direction) is defined as the Y direction, and the thickness direction is defined as the Z direction (the X axis, Y axis, and Z axis are perpendicular to each other). In this embodiment, the length of the housing 10 in the X direction is shorter than the length of the housing 10 in the Y direction. However, the length in the X direction and the length in the Y direction may be the same, or the length in the X direction may be longer than the length in the Y direction.

[0019] FIG. 2A is a side cross-sectional view of the display device according to this embodiment when cut along an AA' plane parallel to the XZ plane.

[0020] 2A, a touch sensor 20, a display panel 30, and various circuits 40 are arranged inside the housing 10. These are arranged in the Z direction in the following order from the opening surface (display surface) side (Z-axis positive side) of the housing 10: the touch sensor 20, the display panel 30, and the various circuits 40. The touch sensor 20 and all or a part of the circuits 40 (for example, a control unit or a control circuit) constitute a touch-type input device.

[0021] 2A, the touch sensor 20 includes a protective film (protective layer) 201, a substrate 202, a first detection conductor 203, a piezoelectric film 204, and a second detection conductor 205. In this embodiment, in order to detect a touch position and a pressure with higher sensitivity, the first detection conductor 203 is disposed on the opening surface side of the housing 10 (i.e., closer to the surface touched by a finger) so that a larger commercial power frequency noise can be detected, and the second detection conductor 205 is disposed on the negative Z-axis direction side of the first detection conductor 203.

[0022] The protective film 201 is preferably made of glass, has excellent transparency and insulating properties, and preferably has a thickness of about 1 mm (1.1 mm in this embodiment). The protective film 201 is present in the outermost layer of the opening surface, and is disposed on substantially the entire surface of the base material 202 on the opening surface side of the housing 10. The protective film 201 becomes the operation surface of the display device 1 and the touch-type input device. The protective film 201 may be made of a transparent organic material such as epoxy resin, may be made of an inorganic material such as glass, or may be a mixture of these.

[0023] The substrate 202 is disposed over substantially the entire surface of the protective film 201 opposite to the opening of the substrate 202. The substrate 202 is a rectangular flat plate made of an insulating material and is made of a transparent material. In this embodiment, the substrate 202 is not particularly limited, but polyethylene terephthalate (PET), polycarbonate, cycloolefin polymer (COP), or the like is preferably used.

[0024] The first detection conductor 203 is disposed on the surface of the base material 202 opposite to the surface in contact with the protective film 201. The first detection conductor 203 is connected to a measurement circuit (comprised of an amplifier 401, a multiplexer 402, an analog-to-digital (AD) conversion unit 403, and a signal processing unit 404, which will be described later). Details of the first detection conductor 203 will be described later with reference to FIGS. 2B to 2E.

[0025] The piezoelectric film 204 is a rectangular flat plate having approximately the same size as the base material 202, and is disposed on the surface of the first detection conductor 203 opposite to the opening surface side of the housing .

[0026] Since it is necessary for the image on the display panel to be accurately viewed, the piezoelectric film 204 preferably has excellent transparency and high piezoelectricity. The piezoelectric constant of the piezoelectric film is preferably 5 pC / N or more, more preferably 10 pC / N or more, even more preferably 15 pC / N or more, and particularly preferably 20 pC / N or more. From the viewpoint of having high piezoelectricity, a film made of a fluororesin is preferable. In this embodiment, the piezoelectric film 204 is made of polyvinylidene fluoride (PVDF), and its piezoelectric constant d 33 is 20 pC / N. The piezoelectric film 204 may be a film made of a chiral polymer. As the chiral polymer, polylactic acid (PLA), particularly polylactic acid L (PLLA), may be used.

[0027] The piezoelectric film 204 generates electric charges when its flat surface is pressed. The density of the electric charges generated at this time depends on the stress applied to the flat surface in a direction perpendicular to the flat surface (Z direction) due to the pressing.

[0028] In this embodiment, the second detection conductor 205 is a rectangular flat plate having approximately the same size as the substrate 202 and the piezoelectric film 204, and is disposed over approximately the entire surface of the piezoelectric film 204 opposite the opening surface of the housing .

[0029] The second detection conductor 205 is composed of an electrode using a PET film as a base material and a sheet of indium tin oxide (ITO) as a conductive material. Since the detection conductor is also required to accurately view the image on the display panel, it is preferable that the detection conductor has excellent transparency. In addition to ITO, inorganic electrodes such as zinc oxide (ZnO), silver nanowires, carbon nanotubes, and graphene, and organic electrodes mainly composed of polythiophene, polyaniline, etc. may be used as the electrode. By using these materials, a conductive pattern with high transparency can be formed.

[0030] The second detection conductor 205 is preferably connected to the ground potential of the measurement circuit board or a fixed potential having a certain offset voltage from the ground potential to set it as the reference potential. By setting the second detection conductor 205 as the reference potential in this way, the detection signal output via the first detection conductor 203 and the second detection conductor 205 is used for pressure detection and touch position detection.

[0031] The base material 202 and the first detection conductor 203 may be upside down. In other words, the first detection conductor 203 may be disposed on the positive side in the Z direction, and the base material 202 may be disposed on the negative side.

[0032] Next, the first detection conductor 203 will be described with reference to FIGS. 2B to 2E.

[0033] Fig. 2B is a diagram showing a configuration example of the first detection conductor. As shown in Fig. 2B, the first detection conductor 203 includes a first portion 2031 having a substrate 203A made of a PET film and an electrode 203B (also called an ITO electrode or a row electrode 203B) mainly made of ITO, and a second portion 2032 having a substrate 203C made of a PET film and an electrode 203D (also called an ITO electrode or a column electrode 203D) mainly made of ITO. The row electrode 203B and the column electrode 203D are electrically insulated from each other.

[0034] In this embodiment, row electrodes 203B are formed in a desired pattern on one surface of base material 203A by photolithography, and column electrodes 203D are formed in a desired pattern on one surface of base material 203C.

[0035] 2C is a diagram showing the row electrodes when viewed from the Z direction. As shown in FIG. 2C, the row electrode 203B included in the first portion 2031 is located at a position y (1) , y (2) , y (3) , , y (M) In this case, the y (m) andy (m+1) The intervals between the first and second row electrodes 203B are substantially the same (m=1, 2, . . . , M-1). Each of the row electrodes 203B included in the first portion 2031 has a plurality of linear portions 203E extending linearly and a plurality of non-linear portions 203F bulging out from the linear portions 203E. As shown in FIG. 2C, the linear portions 203E extend linearly parallel to the X-axis as viewed from the Z direction. The non-linear portions 203F bulge out from the linear portions 203E in the Y direction as viewed from the Z direction. In one example, as shown in FIG. 2C, the non-linear portions 203F have a substantially square outer contour as viewed from the Z direction. The non-linear portions 203F may have a substantially diamond outer contour depending on the setting of the inter-electrode distance of the row electrodes 203B.

[0036] 2D is a diagram showing the column electrodes when viewed from the Z direction. As shown in FIG. 2D, the column electrode 203D included in the second portion 2032 is located at a position x (1) , x(2) , x (3) , , x (N) In this case, the x (n) and x (n+1) The intervals between the first and second electrodes 203A and 203B are substantially the same (n=1, 2, . . . , N-1). Each of the column electrodes 203D included in the second portion 2032 has a plurality of linear portions 203G extending linearly and a plurality of non-linear portions 203H bulging out from the linear portions 203G. As shown in FIG. 2D, the linear portions 203G extend linearly parallel to the Y axis as viewed from the Z direction. The non-linear portions 203H bulge out from the linear portions 203G in the X direction as viewed from the Z direction. In one example, as shown in FIG. 2D, the non-linear portions 203H have an outer contour of a substantially square shape as viewed from the Z direction. The non-linear portions 203H may have an outer contour of a substantially diamond shape depending on the setting of the inter-electrode distance of the column electrodes 203D.

[0037] FIG. 2E is a diagram showing row electrodes and column electrodes when viewed from the Z direction. As shown in FIG. 2E, the row electrodes 203B included in the first portion 2031 and the column electrodes 203D included in the second portion 2032 are orthogonal when viewed from the Z direction. Note that the row electrodes 203B and the column electrodes 203D intersect with each other when viewed from the Z direction, and the angle of intersection and the interval between the row electrodes 203B and the column electrodes 203D are not particularly limited. For example, the angle of intersection between the row electrodes 203B and the column electrodes 203D may be 30 degrees, 45 degrees, etc. Note that, depending on the angle of intersection between the row electrodes 203B and the column electrodes 203D, the non-linear portions 203F and 203H may have an outer contour of a substantially parallelogram shape.

[0038] As shown in Fig. 2E, each of the row electrodes 203B included in the first portion 2031 and each of the column electrodes 203D included in the second portion 2032 intersect when viewed in the Z direction. Also, as shown in Fig. 2E, the non-linear portion 203F of the row electrode 203B included in the first portion 2031 is disposed between the intersection points of the row electrode 203B and two adjacent non-linear portions 203H when viewed in the Z direction.

[0039] Similarly, each of the column electrodes 203D included in the second portion 2032 and the row electrodes 203B included in the first portion 2031 intersect when viewed in the Z direction. Moreover, the non-linear portions 203H of the column electrodes 203D included in the second portion 2032 are disposed between the intersections of the column electrodes 203D and two adjacent non-linear portions 203F when viewed in the Z direction.

[0040] Furthermore, non-linear portion 203F of row electrode 203B included in first portion 2031 and non-linear portion 203H of column electrode 203D included in second portion 2032 are arranged so as not to overlap when viewed from the Z direction. That is, row electrode 203B included in first portion 2031 and column electrode 203D included in second portion 2032 intersect only at linear portions 203E and 203G, respectively, when viewed from the Z direction.

[0041] When the finger of an operator of the display device 1 touches the operation surface, the finger touches one or more electrodes in each row and column of the first detection conductor 203, and the position coordinates (X, Y) of the row and column corresponding to the touched electrode can be identified.

[0042] The row electrode 203B and the column electrode 203D (i.e., the first portion 2031 and the second portion 2032) may be upside down interchanged. In other words, in the Z direction, the column electrode 203D (second portion 2032) may be arranged on the positive side, and the row electrode 203B (first portion 2031) may be arranged on the negative side.

[0043] The touch sensor 20 (located on the positive Z-axis side from the display panel 30) formed by laminating a protective film 201, a substrate 202, a first detection conductor 203, a piezoelectric film 204, and a second detection conductor 205 can have a total light transmittance of 80% or more.

[0044] In this way, the touch sensor 20 has a structure in which the piezoelectric film 204 is sandwiched between a first detection conductor 203 arranged on the side of the opening surface of the housing 10 from the piezoelectric film 204, and a second detection conductor 205 arranged on the opposite side of the opening surface of the housing 10 from the piezoelectric film 204.

[0045] When the operation surface of the display device 1 is pressed by the finger of an operator, the flat surface of the piezoelectric film 204 is curved, and as described above, an electric charge is generated according to the pressure. A potential difference caused by this generated electric charge occurs between the first detection conductor 203 and the second detection conductor 205. A piezoelectric signal caused by this potential difference is included in a signal from the electrodes (row electrodes and column electrodes) constituting the first detection conductor 203. Therefore, by extracting the piezoelectric signal from the signal from the electrodes, the extracted piezoelectric signal can be obtained as a detection signal for detecting pressure. Here, the signal (change) caused by the pressure applied to the piezoelectric film 204 is generally less than 10 Hz (low frequency).

[0046] On the other hand, when the finger of the operator of the display device 1 touches the operation surface, the signal from the electrode constituting the first detection conductor 203, which corresponds to the touch position, contains commercial power frequency noise caused by the finger approaching the electrode. Therefore, by determining the commercial power frequency, the position of the electrode that is the source of the noise (signal) can be detected as the touch position.

[0047] The display panel 30 of this embodiment is composed of a flat panel display having a liquid crystal display element (not shown). The display panel 30 includes a liquid crystal panel, a front polarizing plate, a rear polarizing plate, and a backlight (none of which are shown). The front polarizing plate and the rear polarizing plate are arranged to sandwich the liquid crystal panel. The backlight is arranged on the opposite side of the liquid crystal panel, sandwiching the rear polarizing plate. The display panel 30 displays an image by superimposing it on the touch-type input device. Note that the display panel 30 is not limited to the above configuration, and may be any display panel, such as a flat panel display having an organic EL (Electro-Luminescence) element.

[0048] As described with reference to FIG. 3, the various circuits 40 include an amplifier (AMP) 401 (amplification circuit), a multiplexer 402, an analog-digital (AD) conversion unit 403 (AD converter, AD conversion circuit), a signal processing unit 404 (signal processing circuit), and a controller 405, and further include a drive unit (drive circuit; not shown) that drives the display panel 30 to control the liquid crystal display element. The various circuits 40 are arranged on the back side of the display panel 30. For example, a mounting board (not shown) is arranged in the space on the back side of the display panel 30 in the housing 10, and the various circuits 40 are mounted on the mounting board. All or a part of the various circuits 40 (for example, the signal processing unit 404, the controller 405) may be referred to as a control unit or a control circuit.

[0049] FIG. 3 is an explanatory diagram for explaining the configuration of the display device according to the present embodiment.

[0050] As described above, the first portion 2031 of the first detection conductor 203 includes a plurality (M) of row electrodes, and the second portion 2032 of the first detection conductor 203 includes a plurality (N) of column electrodes.

[0051] Each of the M row electrodes 203B outputs (transmits) an analog signal to the amplifier 401. Each of the N column electrodes 203D outputs (transmits) an analog signal to the amplifier 401. The number of amplifiers 401 is equal to the sum of the number of row electrodes 203B and the number of column electrodes 203D (i.e., M+N).

[0052] The amplifier 401 amplifies the analog signals input (received) from each of the M row electrodes 203B and the N column electrodes 203D to a measurable amplitude range (0 to 3.3 V in this embodiment) and outputs the amplified signals to the multiplexer 402.

[0053] The multiplexer 402 multiplexes analog signals input from M row electrodes 203B via the amplifier 401, and multiplexes analog signals input from N column electrodes 203D via the amplifier 401. The multiplexer 402 multiplexes y (1) , y (2) , y (3) , , y (M) The amplified analog signal AS from each of the row electrodes 203B at the position (y1) , A.S. (y2) , A.S. (y3) , ,AS (yM) are sequentially output to the AD conversion unit 403, and x (1) , x (2) , x (3) , , x (N) The amplified analog signal AS from each of the column electrodes 203D at the position (x1) , A.S. (x2) , A.S. (x3) , ,AS (xN) The multiplexer 402 sequentially outputs the analog signals input via the amplifier 401 from the M row electrodes 203B and the N column electrodes 203D to the AD converter 403. The multiplexer 402 may multiplex the analog signals input from the M row electrodes 203B and the N column electrodes 203D together.

[0054] The AD conversion unit 403 converts the (amplified) analog signal AS input from the multiplexer 402 into (y1) ~AS (yM) are respectively digital signals DS (y1) ~DS (yM) and convert it to a digital signal DS (y1) ~DS (yM) are sequentially output to the signal processing unit 404, and the (amplified) analog signal AS (x1) ~AS (xN) are respectively digital signals DS (x1) ~DS (xN) and convert it to a digital signal DS (x1) ~DS (xN) The digital signals output from the AD conversion unit 403 to the signal processing unit 404 are digital signals DS(y1) Digital signal DS (xN) The output is repeated continuously and periodically at a constant period (for example, 5 milliseconds), with the output up to 10 ...

[0055] The signal processing unit 404 executes the following processes (frequency separation process, envelope detection process, touch determination process, low-pass filter (LPF) process, and pressure measurement process) on the digital signal input from the AD conversion unit 403 at regular intervals (cycles) (i.e., repeatedly cyclically) in accordance with the selection signal input from the controller 405. The processes of the signal processing unit 404 will be described below with reference to FIG. 4 as appropriate. Note that the processes executed by the signal processing unit 404 (or the controller 405) described below may be realized by hardware, software, or a combination of hardware and software.

[0056] [Frequency separation processing] Before the frequency separation process, first, signal processing unit 404 performs offset adjustment on the digital signal input from AD conversion unit 403. Signal processing unit 404 separates digital signal A after the offset adjustment into a first signal B (also referred to as commercial power frequency component B) and a second signal E (also referred to as frequency component E other than the commercial power frequency component) (frequency separation process shown in FIG. 4). Specifically, since digital signal A input from AD conversion unit 403 has commercial power frequency noise caused by a finger touch and a piezoelectric signal caused by a force applied to piezoelectric film 204 superimposed thereon, signal processing unit 404 separates commercial power frequency component B from frequency component E other than the commercial power frequency component including the piezoelectric signal.

[0057] In one example of the frequency separation process, the signal processing unit 404 may use a commercial power frequency band pass filter (band pass filter; for example, a filter having the filter frequency characteristics shown in FIG. 7) to separate the (offset adjusted) digital signal A input from the AD conversion unit 403 into a commercial power frequency component B that passes through the filter and a frequency component E other than the commercial power frequency component that does not pass through the filter. As described above, a signal (change) due to a pressure (touch) applied to the piezoelectric film 204 is generally less than 10 Hz and is therefore included in the frequency component E other than the commercial power frequency component.

[0058] In another example of the frequency separation process, signal processing unit 404 may use a notch filter (band cut filter or band stop filter; not shown) to separate digital signal A (after offset adjustment) input from AD conversion unit 403 into commercial power frequency component B that does not pass through the filter and frequency component E other than the commercial power frequency component that passes through the filter. In this example, signal processing unit 404 can obtain commercial power frequency component B by subtracting frequency component E other than the commercial power frequency component from the detected digital signal A.

[0059] [Envelope detection processing] The signal processing unit 404 performs envelope detection processing of the waveform shown in Fig. 4 on the signal B of the commercial power frequency component obtained as described above, to calculate an envelope signal C. Note that a known technique such as a Hilbert transform may be used to obtain the envelope signal C.

[0060] [Touch detection processing] Since the value of the envelope signal C from a touched electrode is larger than that of an untouched electrode, the signal processor 404 can determine whether or not there is a touch for each electrode region corresponding to the position coordinates (X, Y) based on a preset threshold (touch determination process shown in FIG. 4). For example, the signal processor 404 determines that a period during which the value of the envelope signal C exceeds a predetermined threshold is touched for each electrode region corresponding to the position coordinates (X, Y), and outputs to the controller 405 a signal (signal indicating that there is a touch) that is at a high level only during the period during which there is (is) being touched (determined to be) being touched.

[0061] In the signal processing unit 404, the touch determination process using envelope detection has been shown, but a similar touch determination process can be performed by Fourier transforming the obtained signal. Signal B of the commercial power frequency component is continuously cut out for a certain period (frame), and the frames are Fourier transformed to obtain a spectrum of the piezoelectric signal strength against frequency. In the spectrum, the strength at the commercial power frequency of a touched electrode is greater than that of an untouched electrode, so it is possible to determine whether or not each electrode is touched. For example, if the strength of the commercial power frequency of a certain electrode exceeds a predetermined threshold, it can be determined that the electrode is touched at the time of measurement.

[0062] [LPF processing] As described above, the frequency components E other than the commercial power frequency components include a piezoelectric signal. The signal processing unit 404 performs the LPF process shown in FIG. 4 by using an LPF (for example, a filter having the filter frequency characteristics shown in FIG. 5) for extracting only the piezoelectric signal, thereby obtaining a piezoelectric signal F.

[0063] [Pressure measurement processing] The signal processing unit 404 measures the pressure of each region of the electrode corresponding to the position coordinates (X, Y) based on the obtained piezoelectric signal F, and outputs a pressure signal indicating the measured pressure (pressure) to the controller 405. Specifically, the signal processing unit 404 can measure the pressure of each region of the electrode corresponding to the position coordinates (X, Y) by referring to information (e.g., a table or a formula) that associates the magnitude of the piezoelectric signal with the pressure, which is stored in advance in a storage unit (not shown) of the display device 1.

[0064] The controller 405 outputs a selection signal to the multiplexer 402 for sequentially outputting the amplified analog signals from each electrode to the AD conversion unit 403. The controller 405 outputs a selection signal to the signal processing unit 404 for executing the above-mentioned signal processing on each digital signal input from the AD conversion unit 403.

[0065] The controller 405 detects the touch position and pressure in real time based on the signal input from the signal processing unit 404.

[0066] The controller 405 can identify (i.e., detect) the touch position based on the signal indicating the touch determination processing result input from the signal processing unit 404 and position information (e.g., position coordinates (X, Y)) pre-stored in the storage unit. For example, when the value of the envelope signal C exceeds a threshold, the controller 405 may detect the position of the area corresponding to the envelope signal among the areas covered by the plurality of row electrodes 203B and the plurality of column electrodes 203D as the touch position.

[0067] Furthermore, the controller 405 can identify (ie, detect) the pressure for each region of the electrode corresponding to the position coordinates (X, Y) based on the pressure signal indicating the pressure measurement processing result input from the signal processing unit 404.

[0068] According to this embodiment, since there is no need to limit the period of pressure detection, it is possible to detect the touch position and pressure almost simultaneously. Moreover, by separating the signal detected from the first detection conductor 203 into a first signal for detecting the touch position and a second signal for detecting the pressure, it is possible to detect the touch position and pressure with high sensitivity. Moreover, by arranging the first detection conductor 203 on the opening side, it is possible to detect the touch position from the first signal with high sensitivity and high accuracy. Moreover, since the touch position is detected using a band cut filter or the like required for signal processing of a normal sensor (i.e., no additional circuit is required), it is possible to provide an input device and a display device with a simple configuration.

[0069] Moreover, according to this embodiment, the touch position can be determined with a wiring area smaller than the wiring area required when determining the touch position by arranging rectangular divided electrodes in a matrix on the same plane, and therefore the possibility of erroneous determination can be reduced and the touch position can be determined with higher accuracy. This will be described below.

[0070] When extracting signals from rectangular split electrodes arranged on the same plane in a matrix, the signal lines from the split electrodes cross the effective area of ​​the touch panel. Therefore, there is a possibility that the operator will touch this wiring part. In this case, even if the touched area is small, the hum noise will be propagated to the amplifier through the wiring parts, and it will be erroneously determined that multiple rectangular electrodes have been touched. If the number of electrodes is increased to detect the touch position with higher resolution, the area of ​​the wiring parts will also increase proportionally, and the frequency of erroneous determination will become increasingly high.

[0071] On the other hand, in the electrode pattern according to the present embodiment, the signal line is drawn through the center of the electrode, so even if a finger touches this signal line, the signal that transmits the hum noise will be on the same row or column as the touch position. Therefore, there is no difference in the coordinates on the X-axis and Y-axis where the hum noise is detected, and it is possible to eliminate or reduce erroneous judgments that occur when rectangular divided electrodes are arranged on the same plane in a matrix shape.

[0072] <Modification> In the above embodiment, a notch filter is used to obtain signals other than the commercial power frequency, but a method of applying an LPF that removes bands including the commercial power frequency may be considered to obtain the same effect as the entire signal processing unit 404. Hereinafter, this method using the signal processing unit 404 will be described with reference to Fig. 6. In this method, frequency separation processing is not performed.

[0073] [Bandpass filtering] Prior to bandpass filter processing (and LPF processing described below), first, signal processing unit 404 performs offset adjustment on the digital signal input from AD conversion unit 403. Signal processing unit 404 uses a commercial power frequency bandpass filter (bandpass filter; for example, a filter having the filter frequency characteristics shown in FIG. 7) to extract commercial power frequency component B that has passed through the filter from digital signal A (after offset adjustment) input from AD conversion unit 403.

[0074] [Envelope detection processing] The envelope detection processing in this method is the same as or similar to the envelope detection processing described with reference to FIG. 4, and therefore a description thereof will be omitted.

[0075] [Touch detection processing] The touch determination process in this method is the same as or similar to the touch determination process described with reference to FIG. 4, and therefore will not be described.

[0076] [LPF processing] The digital signal A (after offset adjustment) input from the AD conversion unit 403 contains not only commercial power frequency noise (commercial power frequency components) but also a piezoelectric signal. Therefore, the signal processing unit 404 performs LPF processing shown in Fig. 6 by using an LPF (for example, a filter having the filter frequency characteristics shown in Fig. 5) for removing the commercial power frequency and extracting only the piezoelectric signal, thereby obtaining a piezoelectric signal F.

[0077] [Pressure measurement processing] The pressure measurement process in this method is the same as or similar to the pressure measurement process described with reference to FIG. 4, and therefore will not be described.

[0078] In this modification, by combining a plurality of filter blocks in this manner, it is possible to obtain the same or similar effects as in the above embodiment.

[0079] <Other Modifications> In the above embodiment and modified examples, signal processing is realized by using a frequency filter such as a notch filter as a digital filter after digital signal conversion, but the same function can be realized by using an analog filter instead of a digital filter.

[0080] In the above embodiment and modified examples, it has been described that the controller 405 determines the touch position based on the touch determination processing result by the signal processing unit 404. However, the signal processing unit 404 may determine the touch position based on the touch determination processing result and position information pre-stored in the memory unit.

[0081] In the above embodiment and modified example, the signal processing unit 404 measures the pressure based on the obtained piezoelectric signal and outputs a pressure signal indicating the measured pressure (pressure) to the controller 405. However, the controller 405 may measure the pressure. In this case, for example, the signal processing unit 404 outputs information indicating the magnitude of the obtained piezoelectric signal to the controller 405, and the controller 405 can measure the pressure based on the information indicating the magnitude of the piezoelectric signal input from the signal processing unit 404 by referring to information previously stored in the storage unit that corresponds to the magnitude of the piezoelectric signal and the pressure. For example, when the value of the envelope signal C exceeds a threshold value, the controller 405 may detect the pressure in a region covered by the row electrodes 203B and the column electrodes 203D that corresponds to the envelope signal based on the information that corresponds to the magnitude of the piezoelectric signal and the pressure.

[0082] Second embodiment Next, a second embodiment of the present invention will be described. The second embodiment differs from the first embodiment in the configuration of the first detection conductor. Therefore, in the following, the description will be mainly focused on the configuration of the first detection conductor that differs from the first embodiment, and the description of the same or similar configuration as the first embodiment may be omitted.

[0083] 1 and 2A, the display device 1 according to this embodiment also includes a housing 10 having a substantially rectangular parallelepiped shape, and a touch sensor 20, a display panel 30, and various circuits 40 are disposed inside the housing 10. The touch sensor 20 includes a protective film (protective layer) 201, a substrate 202, a first detection conductor 203, a piezoelectric film 204, and a second detection conductor 205.

[0084] Next, the first detection conductor 203 according to this embodiment will be described with reference to FIGS. 8A to 8C.

[0085] Fig. 8A is a diagram showing a configuration example of the first detection conductor. As shown in Fig. 8A, the first detection conductor 203 includes a PET film as a base material 203A, a first portion 2031 having an electrode (ITO electrode or row electrode) 203B mainly made of ITO, an insulating layer 2033, and a second portion 2032' having an electrode (ITO electrode or column electrode) 203D mainly made of ITO. The row electrode 203B and the column electrode 203D are electrically insulated from each other.

[0086] Unlike the first embodiment, in the second embodiment, only one base material 203A is provided as a base material for the first detection conductor, and the column electrodes 203D are laminated on the row electrodes 203B by photolitho-etching.

[0087] Fig. 8B is a diagram showing row electrodes and column electrodes when viewed from the Z direction, and Fig. 8C is a side cross-sectional view of first detection conductor 203 in an intersection region where the row electrodes and column electrodes shown in Fig. 8B intersect. As shown in Fig. 8B and Fig. 8C, in intersection region R, insulating layer 2033 is provided between row electrode 203B and column electrode 203D.

[0088] Next, a manufacturing process for a part (the first detection conductor 203 and the protective film 201) of the touch sensor 20 according to the second embodiment will be described.

[0089] First, ITO (row electrodes 203B and column electrodes 203D) is deposited and patterned by photolithographic etching. Here, non-linear portions 203F are connected by linear portions 203E in the X direction, but non-linear portions 203H are not connected in the Y direction.

[0090] Next, the insulating layer 2033 is formed and patterned by photolithographic etching, thereby achieving insulation at the X-direction coupling parts (linear parts 203E).

[0091] Next, a metal electrode is formed and patterned by photolithography etching, thereby forming a wiring electrode (straight line portion 203G) that connects in the Y direction.

[0092] Next, the protective film 201 is formed.

[0093] As described above, in the second embodiment, the laminated structure of the touch sensor 20 is thinner than that in the first embodiment, and the column electrodes 203D are closer to the protective film 201.

[0094] According to this embodiment, in addition to the effects of the first embodiment, it is possible to detect the touch position and pressure with higher sensitivity.

[0095] <Modification> The modifications described above regarding the first embodiment can also be applied to this embodiment.

[0096] Third embodiment Next, a third embodiment of the present invention will be described. The third embodiment differs from the first embodiment in the configuration of the first detection conductor. Therefore, in the following, the description will be mainly focused on the configuration of the first detection conductor that differs from the first embodiment, and the description of the same or similar configuration as the first embodiment may be omitted.

[0097] 1 and 2A, the display device 1 according to this embodiment also includes a housing 10 having a substantially rectangular parallelepiped shape, and a touch sensor 20, a display panel 30, and various circuits 40 are disposed inside the housing 10. The touch sensor 20 includes a protective film (protective layer) 201, a substrate 202, a first detection conductor 203, a piezoelectric film 204, and a second detection conductor 205.

[0098] Next, the first detection conductor 203 according to this embodiment will be described with reference to FIG.

[0099] Fig. 9 is a diagram showing a configuration example of the first detection conductor. As shown in Fig. 9, the first detection conductor 203 includes a PET film as a base material 203I, and an electrode (ITO electrode or row electrode) 203B mainly made of ITO and an electrode (ITO electrode or column electrode) 203D mainly made of ITO formed on both sides of the base material 203I. The row electrodes 203B and the column electrodes 203D are electrically insulated from each other.

[0100] Unlike the first embodiment, in the third embodiment, only one substrate 203I is provided as the substrate for the first detection conductor, and row electrodes 203B and column electrodes 203D are formed in desired patterns on both sides of the substrate 203I by photolithography.

[0101] More specifically, in this example, far-ultraviolet rays that do not penetrate the base material 203I are used as light for exposing resist films formed on both sides of the base material 203I, and a film having a function of blocking far-ultraviolet rays is used as the base material 203I. This makes it possible to simultaneously expose two resist films with different patterns, and to form electrodes with different patterns on both sides of one base material 203I.

[0102] As described above, in the third embodiment, the laminated structure of the touch sensor 20 is thinner than that in the first embodiment, and the column electrodes 203D are closer to the protective film 201.

[0103] According to this embodiment, in addition to the effects of the first embodiment, it is possible to detect the touch position and pressure with higher sensitivity. Also, since electrodes are formed on both sides of one base material 203I, it is possible to improve the positional accuracy and reduce the complexity of the man-hours.

[0104] <Modification> The modifications described above regarding the first embodiment can also be applied to this embodiment.

[0105] (Effects of the embodiment) The input device included in the display device 1 according to an embodiment of the present invention includes a touch sensor 20, a signal processor 404, and a controller 405. The touch sensor 20 has a piezoelectric film 204 and a first detection conductor 203 including a plurality of row electrodes 203B facing the piezoelectric film 204 and linearly arranged along the X-axis, and a plurality of column electrodes 203D linearly arranged along the Y-axis. The plurality of row electrodes 203B and the plurality of column electrodes 203D are electrically insulated from each other. The touch sensor 20 further has a second detection conductor 205 facing the first detection conductor 203 and arranged on the opposite side of the first detection conductor 203 with the piezoelectric film 204 sandwiched therebetween. The signal processor 404 and the controller 405 separate a signal detected from the first detection conductor 203 using the second detection conductor 205 as a reference potential into a first signal (hum noise) in the commercial power frequency band and a second signal in a frequency band other than the commercial power frequency band. The signal processing unit 404 and the controller 405 detect a touch position on the touch sensor 20 using the first signal, and detect a pressure on the touch sensor 20 using the second signal.

[0106] With the above configuration, since there is no need to limit the period of pressure detection, it becomes possible to detect the touch position and pressure almost simultaneously, and by separating the signal detected from the first detection conductor 203 into a first signal and a second signal, the touch position and pressure can be detected with high sensitivity. In addition, by arranging the first detection conductor 203 on the opening side, the touch position can be detected from the first signal with high sensitivity and high accuracy.

[0107] Furthermore, since the touch position is detected using a band cut filter or the like required for signal processing of a normal sensor (that is, no additional circuitry is required), an input device with a simple configuration can be provided.

[0108] Furthermore, by arranging rectangular split electrodes in a matrix on the same plane, the touch position can be determined with a wiring area that is smaller than the wiring area required to determine the touch position, thereby reducing the possibility of erroneous determination and enabling the touch position to be determined with greater accuracy.

[0109] (Summary of the embodiment) An input device according to one embodiment of the present invention includes a touch sensor and a control unit, wherein the touch sensor has a piezoelectric film, a plurality of first electrodes facing the piezoelectric film and arranged linearly along a first straight line, and a plurality of second electrodes arranged linearly along a second straight line, the first detection conductor including the plurality of first electrodes and the plurality of second electrodes being electrically insulated from each other, and a second detection conductor facing the first detection conductor and arranged on the opposite side of the piezoelectric film from the first detection conductor, and the control unit separates a signal detected from the first detection conductor using the second detection conductor as a reference potential into a first signal in a commercial power frequency band and a second signal in a frequency band other than the commercial power frequency band, detects a touch position using the first signal, and detects a pressure using the second signal.

[0110] In one example, the control unit calculates an envelope signal of the first signal, and when a value of the envelope signal exceeds a threshold, detects the position of an area covered by the multiple first electrodes and the multiple second electrodes that corresponds to the envelope signal as the touch position.

[0111] In one example, the control unit detects a pressure in an area covered by the multiple first electrodes and the multiple second electrodes that corresponds to the envelope signal based on information correlating the value of the second signal with a pressure.

[0112] In one example, the first detection conductor is disposed closer to a surface of the touch sensor that is touched by a finger than the second detection conductor.

[0113] In one example, the control unit separates the first signal and the second signal from the signal using a bandpass filter that passes the commercial power frequency band.

[0114] In one example, the control unit separates the first signal and the second signal from the signal using a band-stop filter that passes a frequency band other than the commercial power frequency band.

[0115] In one example, the piezoelectric film is made of a fluorine-based resin.

[0116] In one example, the touch sensor has a total light transmittance of 80% or more.

[0117] A display device according to one aspect of the present invention includes the input device, a display panel that displays an image superimposed on a surface of the touch sensor opposite to a surface touched by a finger, and a drive unit that drives the display panel.

[0118] According to one aspect of the present invention, it is possible to detect the touch position and pressure substantially simultaneously with high sensitivity.

[0119] Although the embodiments have been described above with reference to the drawings, the present invention is not limited to such examples. It is clear that a person skilled in the art can come up with various modified or altered examples within the scope of the claims. It is understood that such modified or altered examples also belong to the technical scope of the present invention. Furthermore, the components in the embodiments may be arbitrarily combined within the scope of the present invention. [Industrial Applicability]

[0120] One aspect of the present invention is suitable as a touch input device. [Explanation of symbols]

[0121] 1 Display device 10. Chassis 20 Touch Sensor 201 Protective film 202 Base material 203 First detection conductor 203A Base material 203B ITO electrode (row electrode) 203C base material 203D ITO electrode (column electrode) 203E Straight section 203F Non-linear part 203G Straight section 203H Non-linear part 203I Base material 2031 Part 1 2032 Part 2 2032' 2nd part 2033 Insulation layer 204 Piezoelectric Film 205 Second detection conductor 30 Display Panel 40 Circuits 401 Amplification section 402 Multiplexer 403 AD conversion section 404 Signal Processing Unit 405 Controller

Claims

1. An input device including a touch sensor and a control unit, The touch sensor includes: A piezoelectric film; a first detection conductor facing the piezoelectric film, the first detection conductor including a plurality of first electrodes linearly arranged along a first straight line and a plurality of second electrodes linearly arranged along a second straight line, the first electrodes and the second electrodes being electrically insulated from each other; a second detection conductor disposed opposite the first detection conductor across the piezoelectric film; having The control unit is a signal detected from the first detection conductor with the second detection conductor as a reference potential being separated into a first signal in a commercial power frequency band and a second signal in a frequency band other than the commercial power frequency band; Detecting a touch position using the first signal and detecting a pressure using the second signal; Input device.

2. the control unit calculates an envelope signal of the first signal, and when a value of the envelope signal exceeds a threshold, detects, as the touch position, a position of an area covered by the plurality of first electrodes and the plurality of second electrodes, the position of the area corresponding to the envelope signal. The input device according to claim 1 .

3. the control unit detects a pressure in a region corresponding to the envelope signal based on information associating a value of the second signal with a pressure. The input device according to claim 2 .

4. The first detection conductor is disposed closer to a surface of the touch sensor that is touched by a finger than the second detection conductor. The input device according to claim 1 .

5. The control unit separates the first signal and the second signal from the signal using a bandpass filter that passes the commercial power frequency band. The input device according to claim 1 .

6. the control unit separates the first signal and the second signal from the signal using a band-stop filter that passes a frequency band other than the commercial power frequency band. The input device according to claim 1 .

7. The piezoelectric film is made of a fluorine-based resin. The input device according to claim 1 .

8. The total light transmittance of the touch sensor is 80% or more. An input device according to any one of claims 1 to 7.

9. An input device according to claim 8; a display panel that displays an image on a surface of the touch sensor opposite to a surface touched by a finger; A drive unit that drives the display panel; A display device comprising:

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