Patent Publication Number: US-2023136362-A1

Title: Detection device and detection method

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Japanese Patent Application No. 2021-178055, filed on Oct. 29, 2021, the entire disclosure of which is incorporated by reference herein. 
     FIELD 
     This application relates generally to a detection device and a detection method. 
     BACKGROUND 
     There is a demand for an interface that receives user&#39;s instructions by user gestures. For example, Unexamined Japanese Patent Application Publication (Translation of PCT Application) No. 2016-526213 discloses a switch actuation device including a gesture sensor configured to output a signal having signal shake corresponding to temporal intensity change of detected heat for each pixel that detects heat when a translational gesture is performed. In Unexamined Japanese Patent Application Publication (Translation of PCT Application) No. 2016-526213, a signal caused by the translational gesture and a noise signal are discriminated by inspecting whether an absolute value of the signal shake exceeds a predetermined level. 
     In Unexamined Japanese Patent Application Publication (Translation of PCT Application) No. 2016-526213, since the signal caused by the gesture and the noise signal are discriminated only by the absolute value of the signal shake, when the level of the signal caused by the gesture is small (when the distance between the sensor and the gesture is long), discrimination between the signal caused by the gesture and the noise signal is difficult. 
     SUMMARY 
     A detection device according to a first aspect of the present disclosure includes: 
     a sensor that includes a driving electrode and detection electrodes; and 
     a controller that detects a non-contact target from signal waveforms acquired from the detection electrodes by applying a voltage to the driving electrode, the signal waveforms each indicating a change in signal strength over time, 
     wherein the controller discriminates a peak caused by the non-contact target on the basis of a time width from a rising start point of a peak to a peak top of the peak, a height from the rising start point of the peak to the peak top of the peak, and a slope of a rising side of the peak, in the signal waveform. 
     A detection method according to a second aspect of the present disclosure includes: 
     acquiring signal waveforms from detection electrodes by applying a voltage to a driving electrode; 
     the signal waveforms each indicating a change in signal strength over time, discriminating a peak caused by a non-contact target on the basis of a time width from a rising start point of a peak to a peak top of the peak, a height from the rising start point of the peak to the peak top of the peak, and a slope of a rising side of the peak, in the signal waveform; and 
     detecting the non-contact target on the basis of the discriminated peak caused by the non-contact target. 
     It is to be understood that both the accordingly general description and the following detailed description are granular and explanatory and are not restrictive of this disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete understanding of this application can be obtained when the following detailed description is considered in conjunction with the following drawings, in which: 
         FIG.  1    is a diagram illustrating a detection device according to Embodiment 1; 
         FIG.  2    is a plan view illustrating a sensor according to Embodiment 1; 
         FIG.  3    is a schematic diagram illustrating a display unit according to Embodiment 1; 
         FIG.  4    is a block diagram illustrating the configuration of a controller according to Embodiment 1; 
         FIG.  5    is a diagram illustrating a moving averaged signal waveform according to Embodiment 1; 
         FIG.  6    is a diagram illustrating a first-order differential waveform according to Embodiment 1; 
         FIG.  7    is a diagram illustrating a second-order differential waveform according to Embodiment 1; 
         FIG.  8    is a diagram illustrating a rising start point and a peak top of a peak in a moving averaged signal waveform according to Embodiment 1; 
         FIG.  9    is a block diagram illustrating the hardware configuration of the controller according to Embodiment 1; 
         FIG.  10    is a flowchart illustrating a detection process according to Embodiment 1; 
         FIG.  11    is a flowchart illustrating a calculation process according to Embodiment 1; 
         FIG.  12    is a flowchart illustrating a peak end point/peak top discrimination process according to Embodiment 1; 
         FIG.  13    is a flowchart illustrating a peak discrimination process according to Embodiment 1; 
         FIG.  14    is a diagram illustrating an example of a peak of a target according to Embodiment 1; 
         FIG.  15    is a flowchart illustrating a non-contact detection process according to Embodiment 1; 
         FIG.  16    is a diagram illustrating an example of a lookup table according to Embodiment 1; 
         FIG.  17    is a diagram illustrating a falling end point in a moving averaged signal waveform according to Embodiment 2; 
         FIG.  18    is a flowchart illustrating a peak end point/peak top discrimination process according to Embodiment 2; 
         FIG.  19    is a schematic diagram illustrating virtual detection electrodes according to Embodiment 3; 
         FIG.  20    is a diagram illustrating an example of a time order of peak tops corresponding to a flick gesture from a +Y direction to a —Y direction according to Embodiment 3; 
         FIG.  21    is a diagram illustrating moving averaged signal waveforms according to Embodiment 3; 
         FIG.  22    is a diagram illustrating moving averaged average signal waveforms according to Embodiment 3; 
         FIG.  23    is a schematic diagram illustrating a clockwise circle gesture according to Embodiment 4; 
         FIG.  24    is a flowchart illustrating a non-contact detection process according to Embodiment 4; 
         FIG.  25    is a diagram illustrating a falling end point in a moving averaged signal waveform according to a modification; and 
         FIG.  26    is a schematic diagram illustrating virtual detection electrodes according to according to a modification. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, a detection device according to embodiments is described with reference to the drawings. 
     Embodiment 1 
     A detection device  10  according to the present embodiments is described with reference to  FIGS.  1  to  16   . The detection device  10  detects a non-contact target (for example, a user&#39;s gesture). First, the overall configuration of the detection device  10  is described. 
     As illustrated in  FIG.  1   , the detection device  10  includes a sensor  20  and a controller  50 . As illustrated in  FIG.  2   , the sensor  20  includes a light-transmissive substrate  22 , a driving electrode  24 , and detection electrodes  26   a  to  26   e . The driving electrode  24  and the detection electrodes  26   a  to  26   e  are formed on the light-transmissive substrate  22 . The controller  50  detects a non-contact target from signal waveforms acquired from the detection electrodes  26   a  to  26   e  by applying a voltage to the driving electrode  24 , the signal waveforms each indicating a temporal change in the signal strength of a signal representing capacitance. In the present specification, in order to facilitate understanding, the following description is given on the assumption that in  FIG.  2   , the right direction (right direction of the paper surface) of the sensor  20  is a +X direction, an upward direction (upward direction of the paper surface) is a +Y direction, and a direction perpendicular to the +X direction and the +Y direction (front direction of the paper surface) is a +Z direction. The signal representing capacitance is also referred to as “signal”, and the signal strength of the signal representing the capacitance is also referred to as “signal strength”. 
     As illustrated in  FIG.  3   , the detection device  10  constitutes a display unit  200  together with a display device  100 . The display unit  200  is mounted on a smartphone, a laptop computer, an information display, or the like. The display device  100  includes a display panel  110  and a display controller  120 . The display panel  110  displays characters, images, or the like. The display panel  110  is a liquid crystal display panel, an organic electroluminescence (EL) display panel, or the like. The display controller  120  controls the display of the display panel  110 . The display controller  120  and the controller  50  of the detection device  10  are connected to each other. 
     The sensor  20  of the detection device  10  is provided on a display surface side of the display panel  110  via an adhesive layer (not illustrated). In this case, the driving electrode  24  of the sensor  20  is located above a display area of the display panel  110 , and the detection electrodes  26   a  to  26   e  of the sensor  20  are located above the outer periphery of the display area of the display panel  110 . Furthermore, a protective cover  202  made of resin is provided on the sensor  20  via an adhesive layer (not illustrated). The detection device  10  detects a non-contact target located in a detection space on the sensor  20 . As a result, the detection device  10  serves as an interface for receiving a user&#39;s instruction for the display of the display device  100 . A thickness L of the detection space is, for example, 150 mm. 
     Next, a specific configuration of the detection device  10  is described. As illustrated in  FIG.  2   , the sensor  20  of the detection device  10  includes the light-transmissive substrate  22 , the driving electrode  24 , and the detection electrodes  26   a  to  26   e.    
     The light-transmissive substrate  22  of the sensor  20  is, for example, a glass substrate. The light-transmissive substrate  22  includes a first main surface  22   a.    
     The driving electrode  24  of the sensor  20  is provided on the first main surface  22   a  of the light-transmissive substrate  22 . The driving electrode  24  has a rectangular shape and is provided in a central portion of the first main surface  22   a . In the present embodiment, the driving electrode  24  covers the display area of the display panel  110  when viewed in the plan view. The driving electrode  24  is electrically connected to the controller  50  via a wiring (not illustrated). 
     The detection electrodes  26   a  to  26   e  of the sensor  20  are provided on the first main surface  22   a  of the light-transmissive substrate  22 , respectively. The detection electrode  26   a  is arranged on the +Y side of the driving electrode  24  and extends in the X direction. The detection electrodes  26   b  to  26   e  are arranged side by side in the X direction on the —Y side of the driving electrode  24 . Each of the detection electrodes  26   a  to  26   e  is electrically connected to the controller  50  via a wiring (not illustrated). 
     The driving electrode  24  and the detection electrodes  26   a  to  26   e  are formed of, for example, indium tin oxide (ITO). The driving electrode  24  and the detection electrodes  26   a  to  26   e  form capacitance between a target (for example, a user&#39;s finger or hand, a pen, or the like). 
     The controller  50  of the detection device  10  detects a non-contact target from the signal waveforms acquired from the detection electrodes  26   a  to  26   e , the signal waveforms each indicating a temporal change in the signal strength of the signal representing the capacitance. First, the functional configuration of the controller  50  is described. As illustrated in  FIG.  4   , the controller  50  includes an input/output device  51 , a storage  52 , a driver  54 , a receiver  56 , a calculator  58 , a first discriminator  62 , a second discriminator  64 , and a detector  66 . 
     The input/output device  51  of the controller  50  inputs/outputs a signal between the controller  50  and the display controller  120  of the display device  100 , a signal between the detector  66  and a controller of an electronic device, or the like. 
     The storage  52  of the controller  50  stores a program, data, a signal received by the receiver  56  and representing capacitance, a signal waveform indicating a change in a signal strength over time, or the like. 
     The driver  54  of the controller  50  applies a voltage to the driving electrode  24  on the basis of an instruction from the controller of the electronic device transmitted via the input/output device  51 . The receiver  56  of the controller  50  receives the signals representing the capacitance from the detection electrodes  26   a  to  26   e.    
     The calculator  58  of the controller  50  calculates a moving averaged signal waveform by performing a moving average process on the signal waveform indicating the temporal change in the signal strength of the signal received by the receiver  56  ( FIG.  5   ). This makes it possible to remove fine noise. Moreover, as illustrated in  FIGS.  6  and  7   , the calculator  58  calculates a first-order differential waveform and a second-order differential waveform of the moving averaged signal waveform. 
     On the basis of the first-order differential waveform and the second-order differential waveform of the moving averaged signal waveform, the first discriminator  62  of the controller  50  discriminates a rising start point of a peak and a peak top of the peak in the moving averaged signal waveform. Specifically, as illustrated in  FIGS.  6  and  7   , the first discriminator  62  sets, as a time corresponding to the rising start point of the peak, a time when a value of the second-order differential waveform changes from a positive value to a negative value and a value of the first-order differential waveform is a positive value. Furthermore, the first discriminator  62  sets, as a time corresponding to the peak top of the peak, an initial time when the value of the first-order differential waveform changes from a positive value to a negative value in the direction in which time elapses from the time corresponding to the rising start point of the peak. Moreover, the first discriminator  62  discriminates the rising start point of the peak and the peak top of the peak from the time corresponding to the rising start point of the peak and the time corresponding to the peak top of the peak. Hereinafter, the rising start point of the peak is also referred to as a “rising start point” and the peak top of the peak is also referred to as a “peak top”. 
     When the peak top is not discriminated even after a predetermined first period (for example, 100 ms) elapses from the time corresponding to the rising start point (that is, when the time corresponding to the rising start point and the time corresponding to the peak top are out of the predetermined first period), the first discriminator  62  may re-discriminate that a point, which has been discriminated as the rising start point, is not the rising start point, and re-discriminate the rising start point in the direction in which time elapses. 
     On the basis of a time width ΔT1 from the rising start point to the peak top, a height ΔH1 from the rising start point to the peak top, and a slope Uc (Uc=ΔH1/ΔT1) on a rising side of the peak, the second discriminator  64  of the controller  50  discriminates a peak caused by the non-contact target in the moving averaged signal waveform. Specifically, the second discriminator  64  discriminates, as the peak caused by the non-contact target in the moving averaged signal waveform, a peak in which the time width ΔT1 is equal to or greater than a predetermined first threshold value Cw (for example, 10 ms), the height ΔH1 is equal to or higher than a predetermined second threshold value Ch (for example, 10 a.u.), and the slope Uc on the rising side is equal to or greater than a third threshold value Cd (for example, 0.15). Hereinafter, the peak caused by the non-contact target is also referred to as a “peak of the target”. 
     In the present embodiment, the peak of the target is discriminated on the basis of the time width ΔT1, the height ΔH1, and the slope Uc on the rising side. Consequently, the detection device  10  can discriminate the peak of the target even though the second threshold value Ch, which is the threshold value of the height ΔH1, is set to be small. That is, the detection device  10  can discriminate the peak of a target having a low signal strength. Furthermore, the detection device  10  discriminates the peak of the target from the rising start point and the peak top, which makes it possible to discriminate the peak of the target when the signal waveform reaches the peak top and to detect the non-contact target in a short time. 
     The detector  66  of the controller  50  detects the movement of the non-contact target from the time order of the peak tops of the peaks of the target in the moving averaged signal waveforms of the detection electrodes  26   a  to  26   e . For example, when the peak tops of the peaks of the target appear in the order of the detection electrode  26   d , the detection electrode  26   c , and the detection electrode  26   b  from the detection electrode  26   e  located on the +X side in the direction in which time elapses, the detector  66  discriminates that a user has made a flick gesture from the +X direction to the −X direction, and detects the user&#39;s flick gesture from the +X direction to the −X direction. 
     The detector  66  outputs a signal representing the detected movement of the non-contact target to the controller of the electronic device provided with the detection device  10 . The signal representing the movement of the non-contact target represents, for example, a key event, a message, or the like set by the user for the flick gesture in the −X direction. The signal representing the detected movement of the non-contact target may be output once or more times for one detection. The detected gesture may be a flick gesture from the +Y direction to the —Y direction, a circle gesture in which the non-contact target moves in a circle, or the like. Hereinafter, the movement of the non-contact target is also referred to as a “movement of the target”. 
       FIG.  9    illustrates the hardware configuration of the controller  50 . The controller  50  includes a central processing unit (CPU)  82 , a read only memory (ROM)  83 , a random access memory (RAM)  84 , an input/output interface  86 , and a circuit  88  having a specific function. The CPU  82  executes programs stored in the ROM  83 . The ROM  83  stores programs, data, signals, or the like. The RAM  84  stores data. The input/output interface  86  inputs and outputs signals between these components. The circuit  88  having a specific function includes a driving circuit, a reception circuit, an arithmetic circuit, or the like. The functions of the controller  50  are implemented by the execution of the programs of the CPU  82  and functions of the circuit  88  having a specific function. 
     Next, a detection process (operation) of the detection device  10  is described with reference to  FIGS.  10  to  16   . Hereinafter, a case where the display unit  200  including the detection device  10  and the display device  100  is mounted on an electronic device is described. As illustrated in  FIG.  10   , the detection process of the detection device  10  is performed in the order of a driving process (step S 100 ), a calculation process (step S 200 ), a peak end point/peak top discrimination process (step S 300 ), a peak discrimination process (step S 400 ), and a non-contact detection process (step S 500 ). After the non-contact detection process (step S 500 ), when an end instruction is not input to the controller  50  (step S 600 ; NO), the detection process of the detection device  10  returns to the calculation process (step S 200 ). When the end instruction is input to the controller  50  (step S 600 ; YES), the detection process of the detection device  10  is ended. 
     In the driving process (step S 100 ), the driver  54  of the controller  50  applies a voltage to the driving electrode  24  on the basis of an instruction from the controller of the electronic device transmitted via the input/output device  51  of the controller  50 , and the receiver  56  of the controller  50  receives a signal representing capacitance from each of the detection electrodes  26   a  to  26   e . The received signal representing the capacitance is stored in the storage  52  of the controller  50 . 
     The calculation process (step S 200 ) is described with reference to  FIG.  11   . In the calculation process (step S 200 ), a moving averaged signal waveform and a first-order differential waveform and a second-order differential waveform of the moving averaged signal waveform are calculated. First, the calculator  58  of the controller  50  performs a moving average process on a signal waveform indicating a temporal change in the signal strength of the signal received by the receiver  56 , and calculates the moving averaged signal waveform in each of the detection electrodes  26   a  to  26   e  (step S 202 ). Subsequently, the calculator  58  calculates a first-order differential waveform and a second-order differential waveform of the calculated moving averaged signal waveform (step S 204 ). 
     Next, the peak end point/peak top discrimination process (step S 300 ) is described with reference to  FIG.  12   . In the peak end point/peak top discrimination process (step S 300 ), a rising start point and a peak top in the moving averaged signal waveform are discriminated on the basis of the first-order differential waveform and the second-order differential waveform of the moving averaged signal waveform. First, the first discriminator  62  of the controller  50  discriminates the rising start point in each of the moving averaged signal waveforms from the first-order differential waveform and the second-order differential waveform of each of the moving averaged signal waveforms along the direction in which time elapses (step S 302 ). The first discriminator  62  discriminates the rising start point by setting, as a time corresponding to the rising start point, a time when a value of the second-order differential waveform changes from a positive value to a negative value and a value of the first-order differential waveform is a positive value. Step S 302  is repeated in the direction in which time elapses until the rising start point is determined (step S 302 ; NO). 
     When the rising start point is discriminated (step S 302 ; YES), the first discriminator  62  determines the peak top in each of the moving averaged signal waveforms from the first-order differential waveform of each of the moving averaged signal waveforms (step S 304 ). The first discriminator  62  discriminates the peak top by setting, as a time corresponding to the peak top, an initial time when the value of the first-order differential waveform changes from a positive value to a negative value in the direction in which time elapses from the time corresponding to the rising start point. 
     Step S 304  is repeated in the direction in which time elapses until the peak top is determined (step S 304 ; NO). When the peak top is not discriminated even after the predetermined first period (for example, 100 ms) elapses from the time corresponding to the rising start point, that is, when the time corresponding to the rising start point and the time corresponding to the peak top are out of the predetermined first period, the rising start point discriminated in step S 302  may be re-discriminated as not being a rising start point, and a rising start point may be discriminated again in the direction in which time elapses after returning to step S 302 . 
     When the peak top is discriminated (step S 304 ; YES), the first discriminator  62  stores, in the storage  52 , a corresponding time and a moving average value of the discriminated rising start point and a corresponding time and a moving average value of the discriminated peak top (step S 306 ), and ends the peak end point/peak top discrimination process (step S 300 ). 
     The peak discrimination process (step S 400 ) is described with reference to  FIGS.  13  and  14   . In the peak discrimination process (step S 400 ), the peak of the target in the moving averaged signal waveform is discriminated on the basis of the time width ΔT1 from the rising start point to the peak top, the height ΔH1 from the rising start point to the peak top, and the slope Uc on the rising side of the peak. First, the second discriminator  64  of the controller  50  calculates the time width ΔT1 (difference between the time corresponding to the peak top and the time corresponding to the rising start point) and the height ΔH1 (difference between the moving average value of the peak top and the moving average value of the rising start point) between the rising start point to the peak top discriminated in the peak end point/peak top discrimination process (step S 300 ) (step S 402 ). Subsequently, the second discriminator  64  calculates the slope Uc (ΔH1/ΔT1) on the rising side of the peak (step S 404 ). 
     Next, the second discriminator  64  discriminates whether a peak is the peak of the target in the moving averaged signal waveform on the basis of the time width ΔT1, the height ΔH1, and the slope Uc on the rising side of the peak (Step S 406 ). Specifically, as illustrated in  FIG.  14   , the second discriminator  64  discriminates, as the peak of the target in the moving averaged signal waveform, a peak in which the time width ΔT1 is equal to or greater than the predetermined first threshold value Cw, the height ΔH1 is equal to or higher than the predetermined second threshold value Ch, and the slope Uc on the rising side is equal to or greater than the third threshold value Cd. A peak, in which the time width ΔT1 is less than the predetermined first threshold value Cw, the height ΔH1 is less than the predetermined second threshold value Ch, and the slope Uc on the rising side is less than the third threshold value Cd, is noise (peak of noise). 
     When the peak is not discriminated as the peak of the target (step S 406 ; NO), the detection process returns to step S 302  of the peak end point/peak top discrimination process (step S 300 ). When the peak is discriminated as the peak of the target (step S 406 ; YES), the peak determination process (step S 400 ) is ended. 
     In the present embodiment, the peak of the target is discriminated on the basis of the time width ΔT1, the height ΔH1, and the slope Uc on the rising side. Consequently, the peak discrimination process (step S 400 ) can discriminate the peak of the target even though the second threshold value Ch, which is the threshold value of the height ΔH1, is small. That is, the detection process can discriminate the peak of a target having a low signal strength. Furthermore, since the peak discrimination process (step S 400 ) discriminates the peak of the target from the rising start point and the peak top, the peak of the target can be discriminated when the signal waveform reaches the peak top, and a non-contact target can be discriminated in a short time. 
     The non-contact detection process (step S 500 ) is described with reference to  FIGS.  15  and  16   . In the non-contact detection process (step S 500 ), the movement (user&#39;s gesture) of the discriminated target is discriminated from the time order of the peak tops of the discriminated target. First, the detector  66  of the controller  50  arranges the detection electrodes  26   a  to  26   e  in the time order of the peak tops in each moving averaged signal waveform (step S 502 ). Subsequently, the detector  66  discriminates the movement (user&#39;s gesture) of the target by referring to a lookup table indicating the relationship between the time order of the peak tops in the moving averaged signal waveforms of the detection electrodes  26   a  to  26   e  and the movement of the target (step S 504 ).  FIG.  16    illustrates an example of the lookup table. For example, when the time order of the peak tops is the order of the detection electrode  26   e , the detection electrode  26   d , the detection electrode  26   c , and the detection electrode  26   b , the detector  66  discriminates that the user has made a flick gesture from the +X direction to the −X direction, and detects the flick gesture from the +X direction to the −X direction. The lookup table is stored in the storage  52  in advance. 
     When the movement of the target is detected (step S 504 ; YES), the detector  66  outputs a signal representing the movement of the detected target to the controller of the electronic device, which is provided with the display unit  200  (detection device  10 ), via the input/output device  51  (step  506 ). When the detector  66  outputs the signal representing the movement of the target, the non-contact detection process (step S 500 ) is ended. When the movement of the target is not detected (step S 506 ; NO), the detection process returns to step S 302  of the peak end point/peak top discrimination process (step S 300 ). 
     As described above, the detection device  10  discriminates the peak of a target on the basis of the time width ΔT1, the height ΔH1, and the slope Uc on the rising side, so that the peak of a target having a small signal strength can be discriminated. Furthermore, the detection device  10  discriminates the peak of the target from a rising start point and a peak top, so that a non-contact target can be detected in a short time. 
     Embodiment 2 
     In Embodiment 1, the detection device  10  discriminates a rising start point of a peak and a peak top of the peak. The detection device  10  may discriminate the rising start point of the peak, the peak top of the peak, and a falling end point of the peak. Hereinafter, the falling end point of the peak is also referred to as a “falling end point”. 
     The detection device  10  of the present embodiment includes a sensor  20  and a controller  50 , similarly to the detection device  10  of Embodiment 1. Since the sensor  20  of the present embodiment is the same as the sensor  20  of Embodiment 1, the controller  50  and a detection process of the present embodiment are described below. 
     The controller  50  of the present embodiment includes an input/output device  51 , a storage  52 , a driver  54 , a receiver  56 , a calculator  58 , a first discriminator  62 , a second discriminator  64 , and a detector  66 , similarly to the controller  50  of Embodiment 1. Since the input/output device  51 , the storage  52 , the driver  54 , the receiver  56 , the calculator  58 , the second discriminator  64 , and the detector  66  of the present embodiment are the same as those of Embodiment 1, the first discriminator  62  of the present embodiment is described. 
     On the basis of the first-order differential waveform and the second-order differential waveform of the moving averaged signal waveform, the first discriminator  62  of the present embodiment discriminates the rising start point, the peak top, and the falling end point in the moving averaged signal waveform. The discrimination of the rising start point and the peak top is the same as in Embodiment 1. As illustrated in  FIGS.  6 ,  7 , and  17   , the first discriminator  62  of the present embodiment discriminates the falling end point by setting, as a time corresponding to the falling end point, a time when the value of the second-order differential waveform changes from a negative value to a positive value and the value of the first-order differential waveform changes is a negative value in the direction in which time elapses from the time corresponding to the peak top. 
     Moreover, when the falling end point is not discriminated even after a predetermined second period (for example, 30 ms) elapses from the time corresponding to the peak top (that is, when the time corresponding to the peak top and the time corresponding to the falling end point are out of the predetermined second period), the first discriminator  62  of the present embodiment re-discriminates that a point, which has been discriminated as the rising start point, and a point, which has been discriminated as the peak top, are not a rising start point and a peak top, and re-discriminates a rising start point in the direction in which time elapses. 
     Next, the detection process of the present embodiment is described. The detection process of the present embodiment is performed in the order of a drive process (step S 100 ), a calculation process (step S 200 ), a peak end point/peak top discrimination process (step S 300 ), a peak discrimination process (step S 400 ), and a non-contact detection process (step S 500 ), similarly to the detection process of Embodiment 1. Since the drive process (step S 100 ), the peak discrimination process (step S 400 ), and the non-contact detection process (step S 500 ) of the present embodiment are the same as those of Embodiment 1, the peak end point/peak top discrimination process (step S 300 ) of the present embodiment is described with reference to  FIG.  18   . 
     First, similarly to the peak end point/peak top discrimination process (step S 300 ) of Embodiment 1, the first discriminator  62  of the controller  50  discriminates the rising start point (step S 302 ) and discriminates the peak top (step S 304 ). When the peak top is discriminated (step S 304 ; YES), the first discriminator  62  discriminates the falling end point in each of the moving averaged signal waveforms from the first-order differential waveform and a second-order differential waveform of each of the moving averaged signal waveforms (step S 305 ). 
     Specifically, the first discriminator  62  discriminates the falling end point by setting, as the time corresponding to the falling end point, the time when the value of the second-order differential waveform changes from a negative value to a positive value and the value of the first-order differential waveform changes is a negative value in the direction in which time elapses from the time corresponding to the peak top. When the falling end point is not discriminated even after the predetermined second period elapses from the time corresponding to the peak top (step S 305 ; NO), the rising start point discriminated in step S 302  and the peak top discriminated in step S 304  are re-discriminated as not being a rising start point and a peak top, respectively, and the peak end point/peak top discrimination process (step S 300 ) is returned to step S 302 . 
     When the falling end point is discriminated with the predetermined second period from the time corresponding to the peak top (step S 305 ; YES), the first discriminator  62  stores, in the storage  52 , a corresponding time and a moving average value of the discriminated rising start point and a corresponding time and a moving average value of the discriminated peak top (step S 306 ), and ends the peak end point/peak top discrimination process (step S 300 ). 
     In the present embodiment, a rising start point and a peak top (that is, the presence or absence of a peak) are discriminated depending on whether a falling end point exists within the predetermined second period from a time corresponding to the peak top. As a result, the detection device  10  of the present embodiment can suppress an increase in signal strength not caused by the movement of a target from being discriminated as a peak, and can suppress erroneous detection. Furthermore, the detection device  10  of the present embodiment can discriminate the peak of a target having a small signal strength, similarly to the detection device  10  of Embodiment 1. 
     Embodiment 3 
     In Embodiment 1 and Embodiment 2, the detection device  10  detects the movement of a target from a signal waveform of each of the detection electrodes  26   a  to  26   e . The detection device  10  may detect the movement of a target from a signal waveform obtained by averaging signal waveforms of detection electrodes (for example, the detection electrodes  26   b  to  26   e ). 
     In the present embodiment, the detection device  10  detects the movement of a target from a signal waveform of each of the detection electrodes  26   a  to  26   e  and a signal waveform obtained by averaging the signal waveforms of the detection electrodes  26   b  to  26   e . The detection device  10  of the present embodiment includes a sensor  20  and a controller  50 , similarly to the detection device  10  of Embodiment 1. Since the sensor  20  of the present embodiment is the same as the sensor  20  of Embodiment 1, the controller  50  and a detection process of the present embodiment are described below. 
     The controller  50  of the present embodiment includes an input/output device  51 , a storage  52 , a driver  54 , a receiver  56 , a calculator  58 , a first discriminator  62 , a second discriminator  64 , and a detector  66 , similarly to the controller  50  of Embodiment 1. Since the input/output device  51 , the storage  52 , the driver  54 , and the receiver  56  of the present embodiment are the same as those of Embodiment 1, the calculator  58 , a first discriminator  62 , the second discriminator  64 , and the detector  66  of the present embodiment are described. 
     Similar to the calculator  58  of Embodiment 1, the calculator  58  of the present embodiment calculates moving averaged signal waveforms of the detection electrodes  26   a  to  26   e  from signals received by the receiver  56 . 
     Then, the calculator  58  of the present embodiment sets a virtual detection electrode including detection electrodes, and calculates a moving averaged signal waveform of the virtual detection electrode. In the present embodiment, as illustrated in  FIG.  19   , virtual detection electrode  26   b - 26   e  is configured from the detection electrodes  26   b  to  26   e . The calculator  58  of the present embodiment calculates an average signal waveform  26   b - 26   e  obtained by averaging the signal waveforms of the detection electrodes  26   b  to  26   e , as a signal waveform of the virtual detection electrode  26   b - 26   e . Then, the calculator  58  of the present embodiment calculates a moving averaged average signal waveform  26   b - 26   e  by performing a moving average process on the average signal waveform  26   b - 26   e.    
     Then, the calculator  58  of the present embodiment calculates first-order differential waveforms and second-order differential waveforms of the moving averaged signal waveforms of the detection electrodes  26   a  to  26   e  and the moving averaged average signal waveform  26   b - 26   e.    
     The first discriminator  62  of the present embodiment discriminates rising start points and peak tops in the moving averaged signal waveforms of the detection electrodes  26   a  to  26   e  and the moving averaged average signal waveform  26   b - 26   e  of the virtual detection electrode  26   b - 26   e . The discrimination of the rising start points and the peak tops is the same as in Embodiment 1. 
     The second discriminator  64  of the present embodiment discriminates a peak of a target in the moving averaged signal waveforms of the detection electrodes  26   a  to  26   e  and the moving averaged average signal waveform  26   b - 26   e  of the virtual detection electrode  26   b - 26   e . The discrimination of the peak of the target is the same as in Embodiment 1. 
     The detector  66  of the present embodiment discriminates the movement of the target from the time order of the peak tops of the peaks of the target in the moving averaged signal waveform of each of the detection electrodes  26   a  to  26   e  and the moving averaged average signal waveform  26   b - 26   e . For example, when the peak top of the peak of the target appears in the order of the detection electrode  26   a  and the virtual detection electrode  26   b - 26   e  in the direction in which time elapses, the detector  66  discriminates that a user has made a flick gesture from the +Y direction to the −Y direction, and detects the user&#39;s flick gesture from the +Y direction to the −Y direction. 
     When the flick gesture from the +Y direction to the −Y direction is discriminated only from the time order of the peak tops of the detection electrodes  26   a  to  26   e , there are time orders of the peak tops corresponding to the flick gesture from the +Y direction to the −Y direction as illustrated in  FIG.  20   , which may complicate discrimination. Furthermore, as illustrated in  FIG.  21   , a signal strength difference and a time difference at the peak tops are reduced, and discrimination may be difficult. 
     In the present embodiment, when the peak top appears in the order of the detection electrode  26   a  and the virtual detection electrode  26   b - 26   e , since it is discriminated that the user has made a flick gesture from the +Y direction to the −Y direction, the detection device  10  of the present embodiment can easily discriminate the movement of a target. Furthermore, as illustrated in  FIG.  22   , the number of signal waveforms to be discriminated is reduced, so that the detection device  10  of the present embodiment can easily discriminate the movement of a target. 
     The detector  66  of the present embodiment outputs a signal representing the movement of the detected target to the controller of the electronic device provided with the detection device  10 . The signal representing the movement of the target represents, for example, a key event, a message, or the like set by the user for a flick gesture in the −Y direction. The detector  66  of the present embodiment may also detect a flick gesture from the +Y direction to the −Y direction from the time order of the peak tops of the detection electrode  26   a , the peak tops of the virtual detection electrode  26   b - 26   e , and the peak tops of the detection electrodes  26   b  to  26   e.    
     Next, the detection process of the present embodiment is described. The detection process of the present embodiment is performed in the order of a drive process (step S 100 ), a calculation process (step S 200 ), a peak end point/peak top discrimination process (step S 300 ), a peak discrimination process (step S 400 ), and a non-contact detection process (step S 500 ), similarly to the detection process of Embodiment 1. Since the drive process (step S 100 ) of the present embodiment is the same as that of Embodiment 1, the calculation process (step S 200 ), the peak end point/peak top discrimination process (step S 300 ), the peak discrimination process (step S 400 ), and the non-contact detection process (step S 500 ) of the present embodiment are described. 
     In the calculation process (step S 200 ) of the present embodiment, the calculator  58  calculates, as the signal waveform of the virtual detection electrode  26   b - 26   e , the average signal waveform  26   b - 26   e  obtained by averaging the signal waveforms of the detection electrodes  26   b  to  26   e , and further calculates the moving averaged average signal waveform  26   b - 26   e . The calculator  58  calculates the first-order differential waveform and the second-order differential waveform of the moving averaged average signal waveforms  26   b - 26   e . The other processes in the calculation process (step S 200 ) of the present embodiment are the same as the calculation process (step S 200 ) of Embodiment 1. 
     In the peak end point/peak top discrimination process (step S 300 ) of the present embodiment, the first discriminator  62  discriminates the rising start points and the peak tops in the moving averaged signal waveforms of the detection electrodes  26   a  to  26   e  and the moving averaged average signal waveform  26   b - 26   e  on the basis of the calculated first-order differential waveforms and second-order differential waveforms. The other processes in the peak end point/peak top discrimination process (step S 300 ) of the present embodiment are the same as the peak end point/peak top discrimination process (step S 300 ) of Embodiment 1. 
     In the peak discrimination process (step S 400 ) of the present embodiment, the second discriminator  64  discriminates the peak of the target in the moving averaged signal waveforms of the detection electrodes  26   a  to  26   e  and the moving averaged average signal waveform  26   b - 26   e  on the basis of the time width ΔT1 from the rising start point to the peak top, the height ΔH1 from the rising start point to the peak top, and the slope Uc on the rising side of the peak. The other processes in the peak discrimination process (step S 400 ) of the present embodiment are the same as the peak discrimination process (step S 400 ) of Embodiment 1. 
     In the non-contact detection process (step S 500 ) of the present embodiment, the detector  66  discriminates the movement (user&#39;s gesture) of the discriminated target from the time order of the peak tops of the peaks of the discriminated target. Similar to Embodiment 1, the detector  66  discriminates the movement of the target by referring to the lookup table indicating the relationship between the time order of the peak tops and the movement of the target. 
     As described above, the detection device  10  of the present embodiment discriminates the movement of a target from signal waveforms obtained by averaging signal waveforms of detection electrodes (detection electrodes  26   b  to  26   e ), so that the target can be easily detected. Furthermore, the detection device  10  of the present embodiment can discriminate the peak of a target having a small signal strength, similarly to the detection device  10  of Embodiment 1. 
     Embodiment 4 
     In Embodiment 1 to Embodiment 3, the detection device  10  discriminates the movement of a target from the time order of peak tops. The detection device  10  may discriminate the movement of the target from the time interval of the peak tops. 
     In the present embodiment, the detection device  10  discriminates the movement of the target from the time order of the peak tops and the time interval of the peak tops. The detection device  10  of the present embodiment includes a sensor  20  and a controller  50 , similarly to the detection device  10  of Embodiment 1. Since the sensor  20  of the present embodiment is the same as the sensor  20  of Embodiment 1, the controller  50  and a detection process of the present embodiment are described below. 
     Similarly to the controller  50  of Embodiment 3, the controller  50  of the present embodiment includes an input/output device  51 , a storage  52 , a driver  54 , a receiver  56 , a calculator  58 , a first discriminator  62 , a second discriminator  64 , and a detector  66 , similarly to the controller  50  of Embodiment 3. Since the input/output device  51 , the storage  52 , the driver  54 , the receiver  56 , the calculator  58 , a first discriminator  62 , and the second discriminator  64  of the present embodiment are the same as those of Embodiment 3, the detector  66  of the present embodiment is described. 
     The detector  66  of the present embodiment classifies the type of movement of a target to be discriminated (type of gesture to be discriminated) from time intervals between the peak tops of the detection electrodes  26   a  to  26   e  and the peak tops of the virtual detection electrode  26   b - 26   e . The detector  66  of the present embodiment classifies, for example, the type of the movement of the target to be discriminated into a flick gesture and a circle gesture from time intervals between the peak tops in the moving averaged signal waveform of the detection electrode  26   a  and the peak tops in the moving averaged average signal waveform  26   b - 26   e  of the virtual detection electrode  26   b - 26   e.    
     Specifically, when a time interval T2 between the peak top of the detection electrode  26   a  and the peak top of the virtual detection electrode  26   b - 26   e  is equal to or less than a predetermined fourth threshold value th4, the detector  66  classifies the type of the movement of the target to be discriminated into the flick gesture. When the time interval T2 between the peak top of the detection electrode  26   a  and the peak top of the virtual detection electrode  26   b - 26   e  is greater than the predetermined fourth threshold value th4 and smaller than a predetermined fifth threshold value th5, the detector  66  classifies the type of the movement of the target to be discriminated into the circle gesture. Since the time from the start to the end of a movement in the flick gesture is shorter than the time from the start to the end of a movement in the circle gesture, the detector  66  can classify the type of the movement of the target to be discriminated into the flick gesture and the circle gesture according to the time interval of the peak tops. 
     The detector  66  of the present embodiment further discriminates the movement of the target from the time order of the peak tops of the detection electrodes  26   a  to  26   e  and the peak tops of the virtual detection electrode  26   b - 26   e  for each classified type of movement of the target to be discriminated. For example, when the type of the movement of the target to be discriminated is discriminated as the circle gesture and the time order of the peak tops is the order of the peak top of the detection electrode  26   a  and the peak top of the virtual detection electrode  26   b - 26   e , the movement of the target is discriminated as a clockwise circle gesture as illustrated in  FIG.  23   . On the other hand, when the type of the movement of the target to be discriminated is discriminated as the circle gesture and the time order of the peak tops is not a time order set in advance, it is discriminated that there is no movement of the target. Furthermore, when the type of the movement of the target to be discriminated is discriminated as the flick gesture and the time order of the peak tops is the order of the peak top of the detection electrode  26   a  and the peak top of the virtual detection electrode  26   b - 26   e , it is discriminated that the movement of the target is a flick gesture from the +Y direction to the −Y direction. 
     In the present embodiment, the detection device  10  discriminates the movement of a target from the time order of peak tops and the time interval of the peak tops, so that movements of a wider variety of target can be more easily discriminated. 
     Next, the detection process of the present embodiment is described. The detection process of the present embodiment is performed in the order of a drive process (step S 100 ), a calculation process (step S 200 ), a peak end point/peak top discrimination process (step S 300 ), a peak discrimination process (step S 400 ), and a non-contact detection process (step S 500 ), similarly to the detection process of Embodiment 1. Since the drive process (step S 100 ), the calculation process (step S 200 ), the peak end point/peak top discrimination process (step S 300 ), and the peak discrimination process (step S 400 ) are the same as those of Embodiment 3, the non-contact detection process (step S 500 ) of the present embodiment is described with reference to  FIG.  24   . 
     In the non-contact detection process (step S 500 ) of the present embodiment, first, the detector  66  of the controller  50  arranges the detection electrodes  26   a  to  26   e  and the virtual detection electrode  26   b - 26   e  in the time order of the peak top (step S 512 ). Next, the detector  66  classifies the type of the movement of the target to be discriminated (type of user&#39;s gesture) from the time intervals between the peak tops of the detection electrodes  26   a  to  26   e  and the peak tops of the virtual detection electrode  26   b - 26   e  (step S 514 ). Specifically, when the time interval T2 between the peak top of the detection electrode  26   a  and the peak top of the virtual detection electrode  26   b - 26   e  is equal to or less than the predetermined fourth threshold value th4, the detector  66  classifies the type of the movement of the target to be discriminated into the flick gesture (step S 514 ; T2≤th4). When the time interval T2 between the peak top of the detection electrode  26   a  and the peak top of the virtual detection electrode  26   b - 26   e  is greater than the predetermined fourth threshold value th4 and smaller than the predetermined fifth threshold value th5, the detector  66  classifies the type of the movement of the target to be discriminated into the circle gesture (step S 514 ; th4&lt;T2&lt;th5). Moreover, when the time interval T2 between the peak top of the detection electrode  26   a  and the peak top of the virtual detection electrode  26   b - 26   e  is the predetermined fifth threshold value th5, the detection process returns to step S 302  of the peak end point/peak top discrimination process (step S 300 ). 
     When the type of the movement of the target to be determined is the flick gesture (step S 514 ; T2≤th4), the detector  66  detects the movement of the target by referring to a lookup table indicating the relationship between the time order of the peak tops and the movement of the target in the flick gesture (step S 516 ). When the movement of the target is not detected (step S 514 ; NO), the detection process returns to step S 302  of the peak end point/peak top discrimination process (step S 300 ). 
     On the other hand, when the type of the movement of the target to be discriminated is the circle gesture (step S 514 ; th4&lt;T2&lt;th5), the detector  66  detects the movement of the target by referring to a lookup table indicating the relationship between the time order of the peak tops and the movement of the target in the circle gesture (step S 518 ). When the movement of the target is not detected (step S 518 ; NO), the detection process returns to step S 302  of the peak end point/peak top discrimination process (step S 300 ). 
     When the movement of the target is detected in step S 516  or step S 516  (step S 516 ; YES or step S 518 ; YES), the detector  66  outputs a signal representing the movement of the detected target to the controller of the electronic device provided with the display unit  200  (detection device  10 ) (step  506 ). When the detector  66  outputs the signal representing the movement of the target, the non-contact detection process (step S 500 ) is ended. 
     As described above, the detection device  10  of the present embodiment discriminates the movement of a target from the time order of peak tops and the time interval of the peak tops, so that movements of a wider variety of targets can be more easily discriminated. Furthermore, the detection device  10  of the present embodiment can discriminate the peak of a target having a small signal strength. 
     Modification 
     Although the embodiments have been described above, the present disclosure can be changed in various ways without departing from the gist. 
     For example, the number and arrangement of the detection electrodes of the sensor  20  are arbitrary. For example, the detection electrodes may be arranged on the +X side and the −X side of the driving electrode  24  to surround the driving electrode  24 . Furthermore, the sensor  20  may include driving electrodes  24 . 
     The detection device  10  may discriminate the peak of a target on the basis of at least one of a time width ΔT3 from a falling end point to a peak top, a height ΔH2 from the falling end point to the peak top, and a slope Dc (ΔH2/ΔT3) on a falling side of the peak illustrated in  FIG.  25   , in addition to the time width ΔT1 from the rising start point to the peak top, the height ΔH1 from the rising start point to the peak top, or the slope Uc on the rising side of the peak. 
     In the embodiments, the detection device  10  performs a moving average process on a signal waveform indicating a change in signal strength over time. The detection device  10  may not perform the moving average process on the signal waveform indicating a change in signal strength over time. For example, the detection device  10  may discriminate a rising start point and a peak top on the basis of a first-order differential waveform and a second-order differential waveform of a signal waveform received by the receiver  56 . 
     In Embodiment 3, the movement of a target is detected from the signal waveform obtained by averaging the signal waveforms of the detection electrodes  26   b  to  26   e  (average signal waveform  26   b - 26   e  of the virtual detection electrode  26   b - 26   e ). The detection electrodes constituting the virtual detection electrode are not limited to the detection electrodes  26   b  to  26   e . For example, as illustrated in  FIG.  26   , the virtual detection electrodes may be configured from the detection electrode  26   a  and the detection electrode  26   b  (virtual detection electrode  26   a - 26   b ), and the detection electrode  26   a  and the detection electrode  26   e  (virtual detection electrode  26   a - 26   e ). For example, when peak tops appear in the order of the virtual detection electrodes  26   a - 26   b , the detection electrode  26   a , the virtual detection electrode  26   a - 26   e , and the virtual detection electrode  26   b - 26   e , the detection device  10  can discriminate a clockwise circle gesture. 
     The controller  50  may include dedicated hardware such as an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), and a control circuit. In this case, each of the processes may be performed by individual hardware. Furthermore, the processes may be collectively performed by single hardware. Some of the processes may be performed by dedicated hardware, and others of the processes may be performed by software or firmware. 
     The foregoing describes some example embodiments for explanatory purposes. Although the foregoing discussion has presented specific embodiments, persons skilled in the art will recognize that changes may be made in form and detail without departing from the broader spirit and scope of the invention. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. This detailed description, therefore, is not to be taken in a limiting sense, and the scope of the invention is defined only by the included claims, along with the full range of equivalents to which such claims are entitled.