JP2016021194A - Touch input device, display device, electronic equipment, touch determination control method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent recognition error with a touch panel which is caused by agreement between a noise frequency and an operation frequency of the touch panel.SOLUTION: There are provided measurement means for acquiring a measurement value of an electrostatic capacitance method touch sensor at a predetermined timing, determination means which determines a touched state when the measurement value obtained by the measurement means exceeds a predetermined reference value, and measurement timing control means which changes a predetermined timing if a fluctuation cycle of the measurement value, in a case where the determination means does not determine the touched state, is within a predetermined range.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a touch input device, a display device, an electronic device, a touch determination control method, and a program.

  In recent years, the spread of electronic devices with touch panels has been remarkable. For example, all mobile phones and tablet-type electronic devices called smartphones include a touch panel. The touch panel detects a touch of a fingertip or the like, and generates a signal such as a touch position and a touch method. A display unit such as a liquid crystal panel is provided on the back of the touch panel, and the display information can be seen through the touch panel. Accordingly, the user can perform an operation such as pressing a button on the screen “intuitively” or scrolling the screen while viewing the display information.

  There are various types of touch panels. In particular, capacitive touch panels are superior to other touch systems in terms of light transmittance and durability, and are becoming the mainstream of today's touch panels. The sensing element of the capacitive touch panel has a structure in which a dielectric is sandwiched between two electrodes (this structure can be regarded as one capacitor equivalently), and touches based on the change in capacitance of the capacitor. It is a mechanism to detect the presence or absence of.

  However, the capacitive touch panel has a weak point that it is inferior in noise (electromagnetic noise) resistance. That is, the capacitance of the capacitor may change due to the noise generated inside and outside the housing. Such a change in capacitance is an unintentional change and leads to erroneous touch detection.

  Therefore, in Patent Document 1, in order to prevent the erroneous detection of the touch described above, it is considered that the sensor measurement value has been touched when the touch threshold value is exceeded, and the touch threshold value is not reached by noise and is only touched. An invention relating to a touch panel touch position detection method for setting a reaching value is disclosed.

JP 2010-61598 A

  Here, as a cause of the touch erroneous detection (false recognition) described above, when an electronic device such as a PC or smartphone equipped with a touch panel is used by acquiring the power from the AC adapter, the operating frequency of the touch panel and the AC adapter are used. It is mentioned that the switching noise frequency at which the noise occurs coincides. The cause is that when the operation frequency and the noise frequency of the panel are synchronized, the reference potential (GND) fluctuates and a slight potential change when the finger is touched cannot be identified. It was found that the coincidence between the operating frequency of the touch panel and the operating frequency of the AC adapter is caused by switching noise from the AC adapter.

  According to the touch position detection method disclosed in Patent Literature 1, by applying different noise reduction parameters to a sensor that shows a high measurement value in touch detection and a sensor group located in the vicinity thereof, the influence of noise Has been reduced. However, the touch position detection method according to Patent Document 1 does not consider the problem of coincidence between the operating frequency of the touch panel and the frequency of noise such as switching noise. Therefore, the touch position detection method disclosed in Patent Document 1 cannot prevent erroneous touch recognition due to the coincidence between the operating frequency of the touch panel and the noise frequency.

  The present invention has been made in view of such circumstances, and an object of the present invention is to prevent erroneous touch recognition resulting from the coincidence of the operating frequency of the touch panel and the noise frequency.

  In order to solve the above problems, a touch input device according to the present invention includes a measurement unit that acquires a measurement value of a capacitive touch sensor at a predetermined timing, and a measurement value acquired by the measurement unit exceeds a predetermined reference value. And a determination means for determining the touch state, and a measurement timing control means for changing the predetermined timing when the fluctuation cycle of the measured value when the determination means does not determine the touch state is within a predetermined range. Features.

  ADVANTAGE OF THE INVENTION According to this invention, the touch misrecognition resulting from the agreement of the operating frequency of a touch panel and a noise frequency can be prevented.

It is a lineblock diagram of electronic equipment 1 of an embodiment of the present invention. 2 is a conceptual configuration diagram of a touch sensor 4. FIG. 4 is a cross-sectional view of a touch unit 9. FIG. It is a principle explanatory view of touch detection. It is a schematic diagram explaining the misrecognition of the touch state determination by noise. It is a schematic diagram explaining the change control of the touch detection timing in the embodiment of the present invention.

  A touch input device according to an embodiment of the present invention will be described below with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified thru | or abbreviate | omitted suitably. First, an outline of an electronic apparatus 1 including the touch input device according to the present embodiment will be described below with reference to FIG.

  FIG. 1 is a configuration diagram of an electronic apparatus 1 to which the touch input device of the present embodiment is applied. In this figure, the electronic device 1 is not particularly limited, but is, for example, a personal computer or a smartphone. The electronic device 1 includes at least a control unit 2, a display panel 3 as a display unit, and a capacitance method. A touch sensor 4 and a power supply unit 5 are provided. In the present embodiment, the display panel 3 and the touch sensor 4 are combined to form a touch panel 50 as a display device.

  The control unit 2 is a control element of a program control system, and a computer (hereinafter referred to as CPU) 7 stores a program stored in a nonvolatile and rewritable memory (for example, a flash memory, a hard disk, or a silicon disk) 6 in advance. By executing this, various functions necessary for the electronic apparatus 1 are realized. The control unit 2 includes a measurement unit that acquires a measurement value of the touch sensor 4 at a predetermined timing and a measurement timing control unit. Details of the measurement timing control means will be described later.

  The display panel 3 is a planar two-dimensional display device such as a liquid crystal display panel or an EL panel, for example, and displays various information output from the control unit 2.

  The touch sensor 4 is a two-dimensional transparent touch device having substantially the same planar size as the display screen of the display panel 3, and is arranged on the screen of the display panel 3. The touch sensor 4 is transparent, and in the figure, the touch sensor 4 is drawn with a slight shift to the lower right with respect to the display panel 3, but this is for convenience of illustration. In practice, the two overlap each other, and the user can view the display information on the display panel 3 from the outside through the touch sensor 4. Details of the touch sensor 4 will be described later.

  The power supply unit 5 refers to a constant voltage power supply such as a transformer AC adapter that converts an AC power supply from a commercial power supply to a DC power supply in order to supply power to the electronic device 1. There are two types of power supply systems for constant voltage power supplies: the series system and the switching system, but the switching system is often adopted because of its high efficiency and light weight. In the switching method, a desired voltage is generated by turning on / off a current at high speed by a semiconductor element. In this switching method, high-frequency noise (switching noise) often occurs. When this high-frequency noise is synchronized with the frequency of a DC signal used in touch determination described later, erroneous recognition of the touch sensor 4 is caused. The present invention is intended to prevent erroneous recognition of the touch panel due to coincidence between the frequency of noise such as switching noise and the operating frequency of the touch panel.

  Next, details of the touch sensor 4 will be described. FIG. 2 is a conceptual configuration diagram of the touch sensor 4. In this figure, the touch sensor 4 includes a touch unit 9 having substantially the same plane size (vertical and horizontal sizes) as the display surface of the display panel 3. The touch unit 9 has a so-called Mutual Capacitance structure including a plurality of electrodes in the vertical direction and the horizontal direction that are uniformly arranged at a minute interval. In this figure, a long electrode having a constant width is used, but the present invention is not limited to this. For example, an electrode having a shape in which squares, rhombuses, or other shapes are connected may be used.

  Here, the vertical direction (vertical direction in the drawing) of the touch unit 9 is referred to as the Y-axis direction, and the horizontal direction (horizontal direction in the drawing) is referred to as the X-axis direction. And X1 to X8 are assigned to the electrodes arranged in the horizontal direction.

  The number of electrodes shown (8 each for X and Y) is merely an example for explanation. Although it depends on the plane size of the touch part 9, it actually reaches several hundred to several thousand. Further, the touch part 9 including the electrodes Y1 to Y8 and X1 to X8 is made of a light-transmitting material, and an arbitrary display displayed on the display surface of the display panel 3 located on the back side of the touch part 9. Information can be viewed through the touch part 9.

  FIG. 3 is a cross-sectional view of the touch unit 9. In this figure, the touch unit 9 is a base transparent plate 10 such as glass or a transparent film disposed in contact with the display surface of the display panel 3, and an X that is sequentially stacked on the base transparent plate 10. An electrode layer 11 and a Y electrode layer 12 and a protective transparent plate 13 made of glass (preferably tempered glass) or acrylic disposed on the upper surface of the Y electrode layer 12 are provided. In addition, when glass or tempered glass is used for the protective transparent plate 13, a protective film (for example, a protective transparent film) for preventing scattering of glass fragments is attached to the glass surface in preparation for possible damage. It is desirable to keep it.

  The X electrode layer 11 is a transparent dielectric film (for example, PET) 14 in which a large number of electrodes X1 to X8 are formed at a minute interval. Similarly, the Y electrode layer 12 is also minutely formed on the transparent dielectric film 15. A large number of spaced electrodes Y1 to Y8 are formed. The electrodes X1 to X8 and Y1 to Y8 are formed by evaporating, applying or printing a transparent conductive material, for example, ITO (Indium Tin Oxide).

  The two electrode layers (X electrode layer 11 and Y electrode layer 12) have the same structure except for the arrangement direction of the electrodes. However, as illustrated, the X electrode layer 11 and the Y electrode layer 12 are sequentially stacked on the base transparent plate 10. In the illustrated example, the Y electrode layer is disposed on the X electrode layer 11. 12 is located, the Y electrode layer 12 is different in that the Y electrode layer 12 is in an upper layer, that is, a position closer to the surface of the touch unit 9 (touch surface 9a). This vertical relationship may be reversed. That is, the X electrode layer 11 may be positioned in the upper layer, but here, the description will be continued assuming that the X electrode layer 11 is in the illustrated vertical relationship (the Y electrode layer 12 is positioned in the upper layer of the X electrode layer 11).

  Returning to FIG. 2 again, the X electrode selector 16 is connected to one end side (upper end side in the figure) of the electrodes X1 to X8, and similarly, the Y electrode is connected to one end side (right end side in the figure) of the electrodes Y1 to Y8. A selection unit 17 is connected. The X electrode selection unit 16 and the Y electrode selection unit 17 select the electrodes X1 to X8 and the electrodes Y1 to Y8 line-sequentially in response to a scanning signal from the scanning driving unit 18. The line sequential method may be either a row (Y) unit or a column (X) unit. For example, each column (X) may be selected in units of rows (Y), or each row (Y) may be selected in units of columns (X). Here, the latter method is adopted. To do. That is, the X electrode selection unit 16 and the Y electrode selection unit 17 first select the X electrode (X1) in the first column in response to the scanning signal from the scanning driving unit 18, The Y electrodes (Y1 to Y8) from the first row to the eighth row are sequentially selected, and then the X electrode (X2) in the second column is selected, while the first row to the eighth row are being selected. The Y electrodes (Y1 to Y8) up to the row are sequentially selected, and finally, while the X electrode (X8) in the eighth column is selected, the first row to the eighth row are selected during the selection. It is assumed that the electrodes X1 to X8 and the electrodes Y1 to Y8 are selected line by line by repeating the operation of sequentially selecting the Y electrodes (Y1 to Y8) up to the row. Note that although the sequential selection method has been described here, the present invention is not limited to this. For example, a skipping selection method such as skipping one or skipping a plurality of lines may be used.

  The 8-contact rotary switches 16a and 17a drawn in the frame of the X electrode selection unit 16 and the Y electrode selection unit 17 schematically show the selection operation of the X electrode selection unit 16 and the Y electrode selection unit 17. Is. The X electrode selection unit 16 selects a drive signal (for example, an AC rectangular wave of about several kHz to several tens of kHz) from the signal source (AC drive) 19 via the contact of the rotary switch 16a. To). Further, the Y electrode selection unit 17 is a drive signal (signal) that passes through the capacitance between the selection electrode (any one of Y1 to Y1) and the X electrode selected by the X electrode selection unit 16 at that time. (Supplied from the source 19) is taken out via the contact of the rotary switch 17a and output to the touch determination unit 20.

  The touch determination unit 20 as the determination unit determines that the touch state is reached when the measurement value acquired by the measurement unit exceeds a predetermined reference value. The reference value is calculated based on the difference between the measured value when the touch sensor 4 is not touched and the measured value when the touch sensor 4 is touched. More specifically, the touch determination unit 20 removes unnecessary signal components from the drive signal extracted via the Y electrode selection unit 17 and converts it to DC, and then the DC signal and a predetermined touch determination threshold (reference value). ) To determine whether there is a touch operation on the touch unit 9, and outputs the determination result to the control unit 2. In the description of the present embodiment, for example, the DC signal is a measured value by the touch sensor 4.

  As described above, for example, the signal source 19 supplies an AC rectangular wave of about several kHz to several tens of kHz to the X electrode selection unit 16 as a drive signal. The operation of the signal source 19 is instructed from the control unit 2. Therefore, the drive signal is supplied to the X electrode selector 16 only during the on period.

  FIG. 4 is a diagram for explaining the principle of touch detection. (A) schematically represents a minimum detection unit (hereinafter referred to as a cell) of the touch sensor 4, and the cell 30 includes a Y electrode 21 (corresponding to one of Y1 to Y8 in FIG. 3) and an X electrode. 22 (corresponding to one of X1 to X8 in FIG. 3) and a dielectric 23 (corresponding to the dielectric film 14 in FIG. 3).

  (B) is an equivalent circuit including the cell 30 and its peripheral circuits. Cell 30 is represented by an equivalent capacitor 24. One end (X electrode 22) of the capacitor 24 is connected to a signal source 25 (corresponding to the signal source 19 in FIG. 2), and the other end (Y electrode 21) of the capacitor 24 includes a voltage detection circuit 26 and a resistor 27. The signal source 25 is connected via a parallel circuit. The voltage detection circuit 26 and the resistor 27 are circuit elements included in the touch determination unit 20 of FIG.

  The signal source 25 (signal source 19 in FIG. 2) outputs an AC rectangular wave Sg (driving signal) of about several kHz to several tens of kHz in response to an ON instruction from the control unit 2. The voltage detection circuit 26 detects the peak value of the input signal and determines whether or not the touch sensor 4 is touched based on the detected voltage. Strictly speaking, touch refers to “contact” with the touch sensor 4 by a finger or the like, but is not limited to this. It may include a state in which a fingertip or the like is extremely close to the touch sensor 4 with a delicate distance (so-called hover state).

  When an AC rectangular wave Sg is applied from the signal source 25 to the X electrode 22, a signal substantially similar to the AC rectangular wave Sg appears on the Y electrode 21. Hereinafter, this signal is referred to as a detection signal Vdet (see FIG. 4B). The illustrated detection signal Vdet has the same rectangular shape as the AC rectangular wave Sg, but this is for convenience of illustration. Actually, the shape corresponds to the charge / discharge time constant of the capacitor 24.

  Here, if the magnitude (peak value) of the detection signal Vdet at the time of non-touch is represented by Va, the magnitude of the detection signal Vdet when the fingertip or the like is touched on the touch sensor 4 is Vb smaller than Va. Become. This is because the capacity of the human body (capacitor 28 shown in the figure) is inserted in series with the capacity of the cell 30 (capacitor 24). That is, in this state, since the currents I1 and I2 flow through the capacitors 24 and 28, the potential (the magnitude of the detection signal Vdet) appearing at both ends of the resistor 27 decreases by the amount of the current I2. Therefore, since the magnitude of the detection signal Vdet becomes a different value (Va> Vb) when touching and when not touching, the touch state can be determined by using an appropriate threshold value. That is, in the above example, an appropriate threshold value is set between Va and Vb, and the “touch state” is determined when the magnitude of the detection signal Vdet falls below the threshold value. The “non-touch state” can be determined. In other words, this is equivalent to determining the touch state / non-touch state based on whether or not the difference between Va and Vb exceeds a predetermined threshold (reference value).

  As described above, the touch unit 9 of the touch sensor 4 is driven in an alternating manner by the drive signal from the signal source 25 (the signal source 19 in FIG. 3). As described above, this drive signal is, for example, an AC rectangular wave of about several kHz to several tens of kHz. When the frequency of the switching noise matches or approximates the operating frequency of the touch sensor 4, erroneous recognition of a touch operation on the touch sensor 4 occurs. Specifically, it is a misrecognition that the touch operation is recognized even though the touch sensor 4 is not touched, or the touch operation is not recognized although the touch sensor 4 is touched.

  This misrecognition is attributed to the fact that the difference between the detection signal of the touch sensor and the reference potential becomes substantially constant due to the coincidence between the fluctuation cycle of the reference potential (value) due to switching noise and the touch detection timing.

  In order to prevent the erroneous recognition, in this embodiment, the measurement timing control unit included in the control unit 2 has a measurement value variation period when the touch determination unit 20 does not determine a touch state within a predetermined range. At this time, the timing for acquiring the measurement value of the touch sensor 4 by the measuring means is changed. Specifically, for example, the measurement timing control means acquires the measurement value of the touch sensor 4 by the measurement means so that the measurement timing control means has a period different from the fluctuation period of the measurement value when the touch determination unit 20 does not determine the touch state. Change the timing.

  Usually, the difference between the touch detection signal as the measurement value of the touch sensor and the reference potential is taken at a predetermined timing, and the touch state is determined based on whether or not the difference exceeds a threshold value. However, if the measurement value of the touch sensor is acquired at the same cycle as the reference potential fluctuation cycle and the difference from the reference potential is taken, the comparison is always made with the same potential. In other words, when the reference potential fluctuation period and the measurement timing match, the reference potential to be compared is always the same. In this case, for example, if the measurement timing falls on the upper limit or lower limit of the amplitude of the reference potential cycle, erroneous recognition occurs. For example, when compared with the upper limit of the amplitude of the reference potential, the detection signal that should originally be determined to be in the touch state does not reach the threshold value, so that it is mistaken for the non-touch state. In addition, when compared with the lower limit of the amplitude of the reference potential, the detection signal that should originally be determined to be in the non-touch state reaches the threshold value, so that it is mistaken for the touch state.

  Therefore, in the present embodiment, as described above, the measurement value of the touch sensor 4 by the measurement unit is acquired so as to have a period different from the fluctuation period of the measurement value when the touch determination unit 20 does not determine the touch state. The misunderstanding is prevented by changing the timing. Note that “when it is within a predetermined range” means when the amplitude is equal to or higher than a certain level in the fluctuation cycle of the reference value.

  The aforementioned erroneous recognition will be described with reference to FIG. FIG. 5A shows how the reference potential Vc fluctuates at a constant fluctuation period due to the influence of noise. In this figure, the touch detection signal Vs is a constant value for convenience of explanation. Further, in this figure, the measurement timing when the difference between the reference potential Vc and the touch detection signal Vs is large is “timing [1]”, and the measurement is performed when the difference between the reference potential Vc and the touch detection signal Vs is small. The timing is “timing [2]”.

  The erroneous recognition at the timing [1] will be described with reference to FIG. A broken line indicates a reference potential in a normal state, that is, a case where the touch detection signal is not affected by noise, and a touch detection signal exceeds a threshold value (thick line) based on the reference potential and is determined to be in a touch state. On the other hand, when the touch detection signal is detected at timing [1], the reference potential varies as shown by the solid line. The touch detection signal based on the reference potential after the fluctuation does not exceed the threshold value and is erroneously recognized as being in a non-touch state.

  Next, misrecognition at timing [2] will be described with reference to FIG. The broken line shows the reference potential when it is normal, that is, not affected by noise, and how the touch detection signal does not exceed the threshold (thick line) based on the reference potential and is determined to be in a non-touch state. is there. On the other hand, when the touch detection signal is detected at timing [2], the reference potential varies as shown by the solid line. The touch detection signal based on the reference potential after the fluctuation exceeds the threshold value and is erroneously recognized as being in a touch state.

  Therefore, in the present embodiment, for example, as shown in FIG. 6, the measurement timing is changed to ½ period, which is half of one period of normal time, as shown in timing [3]. Thereby, since two or more different values are measured as the reference potential, an appropriate reference potential can be obtained and erroneous recognition can be prevented. In the present embodiment, the changed measurement timing is set to ½ period, but other periods may be used as long as different values can be obtained as the touch detection signal.

  Each of the above-described embodiments is a preferred embodiment of the present invention, and various modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Electronic device 2 Control part 3 Display panel 4 Touch sensor 5 Power supply part 6 Memory 7 CPU
DESCRIPTION OF SYMBOLS 9 Touch part 10 Base transparent board 11 X electrode layer 12 Y electrode layer 13 Protective transparent board 14, 15 Dielectric film 16 X electrode selection part 17 Y electrode selection part 18 Scan drive part 19, 25 Signal source (AC drive part) )
DESCRIPTION OF SYMBOLS 20 Touch determination part 21 Y electrode 22 X electrode 23 Dielectric 24 Capacitor 26 Voltage detection circuit 27 Resistance 30 Cell 50 Touch panel Vs Touch detection signal

Claims (7)

Measuring means for acquiring the measurement value of the capacitive touch sensor at a predetermined timing;
A determination unit that determines a touch state when a measurement value acquired by the measurement unit exceeds a predetermined reference value;
A measurement timing control means for changing the predetermined timing when a fluctuation period of the measurement value when the determination means does not determine the touch state is within a predetermined range;
A touch input device comprising:   The measurement timing control means changes a timing at which the measurement value of the touch sensor is acquired by the measurement means so as to have a period different from a fluctuation period of the measurement value when the touch state is not determined by the determination means. The touch input device according to claim 1.   The touch input device according to claim 1, wherein the reference value is calculated based on a difference between a measured value when the touch sensor is not touched and a measured value when the touch sensor is touched. . A display device comprising the touch input device according to any one of claims 1 to 3,
A display device comprising: a display unit that is transparent to the touch sensor and is visible from the outside through the touch sensor.   An electronic apparatus comprising the display device according to claim 4. Acquiring a measurement value of the capacitive touch sensor at a predetermined timing;
Determining the touch state when the acquired measurement value exceeds a predetermined reference value;
A step of changing the predetermined timing when a fluctuation period of the measured value when not determined to be in the touch state is within a predetermined range;
A touch determination control method comprising: A process of acquiring the measurement value of the capacitive touch sensor at a predetermined timing;
A process of determining a touch state when the acquired measurement value exceeds a predetermined reference value;
A process of changing the predetermined timing when a fluctuation period of the measurement value when not determined as the touch state is within a predetermined range;
A program that causes a computer to execute.

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