JP2016085550A - Input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an input device that is less affected by noise even when ground wiring is laid out around electrodes in an edge portion of a touch panel.SOLUTION: An input device 1 includes a control unit 7 which controls a drive electrode selector switch 3 such that, when a connection is switched on between a drive electrode X, of a plurality of drive electrodes (Xthrough X), located closer to an edge of a touch panel 2 and a driver unit 5, another drive electrode Xnext to the drive electrode Xlocated closer to the edge is cut off from the driver unit 5 and the ground by turning a corresponding switch off.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an input device, and more particularly, to an input device including a touch panel that detects a change in capacitance.

  An input device provided with a touch panel is widely used in various electric devices such as in-vehicle devices and portable devices. As this type of input device, for example, a capacitive touch panel device described in Patent Document 1 has been proposed.

  The touch panel device described in Patent Document 1 includes a touch panel in which drive electrodes and detection electrodes are arranged in a grid pattern in directions orthogonal to each other. Connected to the touch panel are a drive electrode changeover switch that connects the selected drive electrode to a signal source and switches to a short circuit state, and a detection electrode changeover switch that connects the selected detection electrode to a detection circuit and switches to a short circuit state. ing.

  The drive electrode changeover switch reduces the influence of noise on the drive electrode that is short-circuited to the signal source by connecting another drive electrode that is not selected to the ground. For one of the detection electrode changeover switches, the influence of noise on the detection electrode that is short-circuited to the detection circuit is reduced by connecting another detection electrode that is not selected to the ground.

  A detection voltage is generated from a signal output from a detection electrode short-circuited to the detection circuit by the detection electrode changeover switch, and the detection target such as a finger is applied to the touch panel by comparing the detection voltage with a threshold voltage. It is detected whether or not it is touched.

JP 2014-52997 A

  By the way, when the noise environment is severe, it is necessary to take measures against noise by laying a ground around the electrode arranged near the edge of the touch panel. However, since the influence of noise due to the ground around the electrodes is greater than the influence of noise due to the ground of other unselected electrodes, the sensitivity of the electrodes arranged near the edge portion of the touch panel is deteriorated.

  In order to prevent this deterioration in sensitivity, it is necessary to set the touch threshold of the entire touch panel to be lowered in accordance with the edge portion of the touch panel. However, if the touch threshold value of the entire touch panel is lowered, it becomes more susceptible to noise and the possibility of erroneous detection increases.

  Accordingly, an object of the present invention is to provide an input device capable of reducing the influence of noise even when a ground is laid around the electrode at the edge of the touch panel.

[1] The present invention relates to a touch panel having a plurality of drive electrodes arranged in parallel in a first direction and a plurality of detection electrodes arranged in parallel in a second direction intersecting the first direction; A drive unit that drives the plurality of drive electrodes; a drive electrode changeover switch that switches the plurality of drive electrodes to the drive unit or ground; a reading unit that reads detection values detected by the plurality of detection electrodes; A detection electrode switching switch that switches the detection electrode to the readout unit or the ground, and a control unit that controls switching of the drive electrode switching switch and switching of the detection electrode switching switch. When the connection state between the drive electrode closer to the edge portion of the touch panel and the drive portion is switched to conduction among the drive electrodes, the edge portion In the input device and controls the drive electrode switching switch to switch to an open disconnect the other of said driving electrodes adjacent to the driving electrodes had way from the driver and the ground.

[2] The control unit according to [1] controls the detection electrode changeover switch so as to sequentially switch all of the plurality of detection electrodes every time the drive electrode is driven.

[3] A peripheral electrode connected to a ground is provided around the plurality of drive electrodes and the plurality of detection electrodes according to [1] or [2].

  According to the present invention, even when a ground is laid around the electrode at the edge portion of the touch panel, it is less likely to be affected by noise, and it is possible to prevent erroneous detection due to noise.

1 is a configuration block diagram of an input device according to an embodiment suitable for the present invention. It is a flowchart which shows the flow of operation | movement by the input device which concerns on embodiment. It is a block diagram for explaining the operation of the electrode changeover switch part of the input device according to the embodiment. It is a block diagram for explaining another operation of the electrode changeover switch section of the input device according to the embodiment. It is a figure for demonstrating the sensitivity on the touchscreen in a comparative example. It is explanatory drawing which contrasted embodiment and the comparative example.

  Preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings.

(Overall configuration of input device)
In FIG. 1, reference numeral 1 indicating the whole indicates an example of a typical input device according to the embodiment. The input device 1 includes a touch panel 2 that detects a change in electrostatic capacitance when a touch operation, a tracing operation, or the like is performed on the operation surface 2a with a detection target such as an operator's finger. Used as a capacitive touch panel device.

As shown in FIG. 1, the touch panel 2 is arranged at substantially equal intervals in the X-axis direction and extends in the Y-axis direction with six first to sixth drive electrodes X _{1 to} X ₆ and Y It has _{six first} to _sixth detection electrodes Y _{1 to} Y 6 that are arranged at substantially equal intervals in the axial direction and extend in the X-axis direction. Each of the drive electrodes X ₁ to X ₆ and detecting electrode Y ₁ to Y _6, are constituted by six electrodes, it is not limited to the illustrated examples.

The drive electrodes X _{1 to} X ₆ and the detection electrodes Y _{1 to} Y ₆ are arranged in a grid pattern in a direction crossing transparent electrodes such as ITO, and the detection electrodes Y _{1 to} Y ₆ are arranged in the drive electrodes X ₁ to X _6. forming an electrostatic capacitance detection point is a portion that intersects with the X _6. A peripheral electrode 8 connected to the ground surrounding the periphery of the drive electrodes X ₁ and X ₆ and the detection electrodes Y ₁ and Y ₆ is provided at the edge portion of the touch panel 2.

A drive electrode changeover switch unit 3 and a detection electrode changeover switch unit 4 are electrically connected to the touch panel 2. Drive electrode switching unit 3 is electrically connected to the driving unit 5 for driving the drive electrodes X ₁ to X _6. The detection electrode changeover switch unit 4 is electrically connected to a reading unit 6 that reads detection values detected by the detection electrodes Y _{1 to} Y ₆ . A control signal output from the control unit 7 is input to the drive electrode changeover switch unit 3 and the detection electrode changeover switch unit 4.

Drive electrode switching unit 3 is composed of first to sixth driving switch 31 to 36 having one terminal electrically connected to the respective driving electrodes X ₁ to X _6. The other terminal of each drive switch 31 to 36 is switched between the drive unit 5 and the respective drive electrodes X ₁ to X ₆ in the conductive state when it is turned on, the drive unit when it is turned off 5 and Open to be disconnected from the ground, or selectively switched to the ground.

The drive unit 5 is electrically connected to the control unit 7 and is configured to output drive signals to the drive electrodes X _{1 to} X ₆ based on the drive control signal output from the control unit 7. Yes.

The detection electrode changeover switch unit 4 includes first to sixth detection switches 41 to 46 having one terminal electrically connected to each of the detection electrodes Y _{1 to} Y ₆ . The other terminals of the detection switches 41 to 46 are switched between the detection electrodes Y _{1 to} Y ₆ and the reading unit 6 when turned on and switched to the ground when turned off. .

Reading unit 6 is electrically connected to the control unit 7, based on the read control signal outputted from the control unit 7, the detection electrodes Y ₁ to Y for each driving of the driving electrodes X ₁ to X _{6 6} The detection signal output from is read as a detection value.

  This detection value is a difference value (Δ value) between the capacitance value when there is no touch input to the touch panel 2 and the capacitance value when there is a touch input, and whether or not a predetermined threshold value is exceeded. The touch input is detected by.

  In the reading unit 6, the coordinates of the detection point where the contact of the detection target is detected are calculated based on the read detection value. The reading unit 6 has a threshold value, and determines the detection point by comparing the threshold value with the detection value. For example, a weighted average method is used to calculate the coordinates of the detection points. The reading unit 6 generates detection information including information on the coordinates of the detection points and outputs the detection information to the control unit 7.

  The control unit 7 is a microcomputer that includes a CPU, a ROM, a RAM, and the like that perform operations and processing on data acquired according to a program. The ROM stores setting data such as electrode selection and connection control performed by the drive electrode changeover switch unit 3 and the detection electrode changeover switch unit 4. The RAM temporarily stores setting data read from the ROM.

  The control unit 7 has means for generating a clock signal, and is configured to generate and output a drive control signal, a read control signal, and a switching control signal based on the clock signal.

The drive control signal is a signal that instructs the output and stop of the drive signal. The read control signal is a signal that generates detection information based on the read detection value and outputs the detection information to the control unit 7. The switching control signals sd _{1 to} sd ₆ and sr _{1 to} sr ₆ output driving signals in the order of the first driving electrode X ₁ to the sixth driving electrode X ₆ to drive the driving switches 31 to 31 of the driving electrode changeover switch unit 3. controls 36 independently independently first detection electrodes Y ₁ from the sixth detection electrode detecting electrode detection switch 41-46 of the switching unit 4 to output the read unit 6 detected value in the order of Y ₆ It is a signal to control.

The control unit 7 configured as described above includes the first drive electrode X ₁ and the drive unit 5 that are closer to the edge of the touch panel 2 among the _first to sixth drive electrodes X _{1 to} X ₆ . when switching the connection state between the conductive, the drive electrode switching unit 3 to switch to open separately from the first second drive electrodes X ₂ driver 5 and the ground adjacent to the drive electrodes X ₁ Configured to control.

The controller 7 is adjacent to the _sixth drive electrode X ₆ even when the connection state between the _sixth drive electrode X ₆ closer to the edge of the touch panel 2 and the drive unit 5 is switched to conduction. the drive electrodes X ₅ of the fifth disconnecting from the drive unit 5 and the ground for controlling the drive electrode switching unit 3 to switch to open.

The control unit 7 further sequentially disconnects all of the _first to _sixth detection electrodes Y _{1 to} Y ₆ from the ground every time the first to _sixth drive electrodes X _{1 to} X ₆ are driven, thereby detecting the electrodes Y _{1 to} Y. _The detection electrode changeover switch unit 4 is controlled so that the connection state between the reading unit 6 and the reading unit 6 is switched to conduction.

(Operation of input device)
Next, an example of the operation of the input device 1 configured as described above will be described with reference to FIGS.

  FIG. 1 shows a state before the drive unit 5 of the input device 1 outputs a drive signal. FIG. 2 is a flowchart showing the flow of operations performed by the input device 1. FIG. 3 is a configuration block diagram for explaining the operation of the electrode changeover switch units 3, 4. FIG. 4 is a configuration block diagram for explaining another operation of the electrode changeover switch units 3, 4.

In FIG. 1, the drive unit 5 is in a stage before outputting a drive signal, and all of the first to sixth drive electrodes X _{1 to} X ₆ and the first to sixth detection electrodes Y _{1 to} Y ₆ are Connected to ground.

In FIG. 2, when a power supply (not shown) is turned on, driving of the input device 1 starts. In the process of step S1, the control unit 7 sets a variable i for sequentially driving the first column of drive electrodes X ₁ column 6 of drive electrodes X ₆ is the last column in the i = 1 is the initial value At the same time, clocking of the clock signal is started. The variable i is the number of columns corresponding to the drive electrodes _X 1 to X _6.

The control unit 7 determines which column of the drive electrodes X _{1 to} X ₆ is selected to output the switching control signal. In the process of step S2, whether selectively performed for outputting a first column switch control signal to the drive electrodes X ₁ of which are located near the edge portion of the touch panel 2, or 1 column other than the N (N =. 2 to 6) are you going to choose for outputting a switching control signal to the drive electrodes X ₂ to X ₆ th column is determined.

In the process of step S2, when it is determined that performing a selection for outputting a switching control signal to the drive electrodes X ₁ of the first column, the program proceeds from step S2 to step S3. In the process of step S3, 2 row drive electrode X ₂ adjacent to the driving electrodes X ₁ of the first column, as shown in FIG. 3, switched to open. Third column drive electrode X ₃ driving electrodes X ₆ of the sixth row is the last row of is maintained in the state of being connected to ground.

Even when it is determined that performing a selection for outputting a switching control signal to the drive electrodes X ₆ of the sixth column, which is located near the edge portion of the touch panel 2, the process proceeds from step S2 to step S3. In the process of step S3, the driving electrodes X ₅ of 5 column adjacent to the drive electrode X ₆ of the sixth column is switched to open. 1 row drive electrode X ₄ from the drive electrodes X ₁ in the fourth column of is maintained in the state of being connected to ground.

If it is determined that performing a selection for outputting a switching control signal from the second row of drive electrodes X ₂ to one of the fifth column of drive electrodes X _5, moves from step S2 to step S4. In the processing of step S4, for example, if the second column to the drive electrodes X ₂ is selectively performed for outputting the switching control signal, the second column of drive electrodes X ₂ other than the drive electrodes X _1, X ₃ ~X ₆ Is dropped to the ground as shown in FIG.

Processing in step S5, the control unit 7 sets a variable j for sequentially switching the detection electrodes _Y 1 to Y ₆ each driving of the driving electrodes _X 1 to X ₆ in the j = 1 is the initial value. This variable j is the number of rows corresponding to the detection electrodes Y _{1 to} Y ₆ .

If the detection electrodes Y ₁ of the first row are selectively performed for outputting the switching control signal, as shown in FIG. 3, an electrical detection electrodes Y ₁ in the first row to the control unit 7 via the read unit 6 Connected. Detection electrodes Y ₆ from the detection electrodes Y ₂ of the sixth row of the second line is maintained in the state of being connected to ground.

In the processing of step S6 in the step S5, the reading unit 6, based on the read control signal outputted from the control unit 7, as a touch detection signal outputted from the detection electrodes Y ₁ in response to the driving electrodes X ₁ The capacitance measurement value (detection value) Δij is read. The read capacitance measurement value Δij is sent to the control unit 7, and the touch position (detection point) is detected depending on whether or not the capacitance measurement value Δij exceeds a predetermined threshold.

The detection electrode changeover switch unit 4 detects the detection electrodes Y _{2 to} Y based on a command from the control unit 7 while the drive electrode X ₁ selected in the process of step S 2 to the process of step S 4 is connected to the drive unit 5. ₆ to select sequentially. Capacitance measurement values from the detection electrodes Y ₂ to Y _6, which is selected is sent to the control unit 7 via the read unit 6, a touch position according to whether the electrostatic capacitance measurement Δij exceeds a predetermined threshold value Is detected.

In the process in next step S7 in the step S6, the selection for outputting a switching control signal from the detection electrodes Y ₁ in the first row by the control unit 7 to the detection electrodes Y ₆ of M (M = 6) th row is the last row It is determined whether it has been done.

In the process of step S7, when the selection of the detection electrodes Y ₆ of the last line is determined not to be finished, the process proceeds from step S7 to step S8. In the process of step S8, j (j = 1~5) the selection is completed selected from row detection electrode Y _j is not completed (j + 1) th row of the detection electrodes Y _{(j + 1)} to output the switching control signal The process of step S6 to the process of step S7 are sequentially repeated.

When the selection of the detection electrodes Y ₆ of the last row is completed, the process proceeds from step S7 to step S9. In the process of step S9, and selects for outputting a next second column switch control signal to the drive electrodes X ₂ of the drive electrodes X ₁ of the first column selection is finished, the processing of step S9 from step S2 Repeat sequentially.

(Contrast between embodiment and comparative example)
Next, the sensitivity on the touch panel 2 of the input device 1 according to the embodiment will be described together with a comparative example.

FIG. 5 shows a comparative example in which the sensitivity on the touch panel is graphed. The measurement position shown on the horizontal axis in the graph is a detection point where the drive electrodes X _{1 to} X ₆ and the detection electrodes Y _{1 to} Y ₆ intersect, and the Δ value shown on the vertical axis is a touch input to the touch panel. This is a difference value between the capacitance value when there is no touch and the capacitance value when there is a touch input.

The sensitivity of the comparative example shown by the solid line in FIG. 5, the driving electrode X ₁ in the first column, if you have made a selection for outputting a switching control signal to the sixth column of the drive electrodes X ₆ is the last column, A state in which the second row of drive electrodes X ₂ adjacent to the first row of drive electrodes X ₁ and the fifth row of drive electrodes X ₅ adjacent to the sixth row of drive electrodes X ₆ are connected to the ground. The sensitivity measured under the conditions maintained in FIG.

As can be seen from FIG. 5, in the comparative example, the drive electrodes X ₁ of the first column, the sensitivity of the drive electrodes X ₆ of the sixth row is the last row, of 2-5 column drive electrodes X ₂ to X _{In FIG. 5} , the Δ value difference with the sensitivity when the selection of outputting the switching control signal is performed becomes worse.

Here, referring to FIG. 6, there is shown an example in which the sensitivity on the touch panel 2 of the embodiment indicated by the two-dot chain line and the sensitivity on the touch panel of the comparative example indicated by the solid line are graphed. Yes. The touch position shown on the horizontal axis in the graph is a detection point where the drive electrodes X _{1 to} X ₆ and the detection electrodes Y _{1 to} Y ₆ intersect, as in FIG. 5, and Δ1 and Δ1 ′ shown on the vertical axis are , A touch threshold value for determining the touch position.

Sensitivity of the embodiment, the drive electrodes X ₁ in the first column, if you have made a selection for outputting a switching control signal to the sixth column of the drive electrodes X ₆ is the last column, the first column of the drive a second row of drive electrodes X ₂ adjacent to the electrodes X _1, shows the sensitivity of conditions of switching the open and drive electrodes X ₅ of 5 column adjacent to the drive electrode X ₆ of the sixth row.

In this embodiment, the sensitivity when the selection of outputting the switching control signal to the drive electrodes X _{2 to} X ₅ in the _{second to} fifth columns is the same as in the comparative example, but the drive electrodes in the first column and X _1, the sensitivity of the drive electrodes X ₆ of the sixth row is the last row, delta value difference between the sensitivity of the drive electrodes X ₂ to X ₅ 2-5 column is small.

As can be seen from FIGS. 5 and 6, in the comparative example indicated by the solid line, the sensitivity of the driving electrode X1 in the _first column and the sensitivity of the driving electrode X6 in the _sixth column, which is the final column, are deteriorated. Therefore, it is necessary to lower the touch threshold value to Δ1. However, lowering the touch threshold value to Δ1 is not preferable because erroneous determination is likely to occur due to the influence of noise.

(Effect of embodiment)
On the other hand, according to the embodiment shown by the two-dot chain line in FIG. 6, the sensitivity can be improved as compared with the comparative example, and the sensitivity of the entire touch panel 2 can be made substantially uniform. In addition, the touch threshold value can be increased to Δ1 ′ as compared with the comparative example, and the influence of noise can be suppressed to a small value by increasing the touch threshold value.

  According to the input device 1 according to the embodiment configured as described above, since the touch threshold can be set high, there is an effect that it is difficult to make erroneous detection due to noise.

  The input device 1 can be attached to various interior components such as an instrument panel, a steering wheel, and a center console of a vehicle.

  Of course, the input device 1 can be effectively used as an input device for remotely operating a vehicle-mounted device, and as an input device for various portable information terminal devices such as a mobile phone and a camera.

  As is clear from the above description, typical embodiments and illustrated examples according to the present invention are illustrated, but the above-described embodiments and illustrated examples do not limit the invention according to the claims. Therefore, it should be noted that not all the combinations of features described in the above embodiments and the illustrated examples are essential to the means for solving the problems of the invention.

DESCRIPTION OF SYMBOLS 1 ... Input device, 2 ... Touch panel, 3 ... Drive electrode changeover switch part, 4 ... Detection electrode changeover switch part, 5 ... Drive part, 6 ... Reading part, 7 ... Control part, 8 ... Ambient electrode, 31-36 ... Drive switch, 41-46 ... detection _{switch, X} 1 to X 6 _... driving _{electrode, Y} 1 to Y 6 _... detection electrode

Claims (3)

A touch panel having a plurality of drive electrodes arranged in parallel in a first direction and a plurality of detection electrodes arranged in parallel in a second direction intersecting the first direction;
A drive unit for driving the plurality of drive electrodes;
A drive electrode changeover switch for switching the plurality of drive electrodes to the drive unit or ground;
A reading unit for reading detection values detected by the plurality of detection electrodes;
A detection electrode changeover switch for switching the plurality of detection electrodes to the readout unit or the ground;
A controller that controls switching of the drive electrode switching switch and switching of the detection electrode switching switch;
With
When the connection state between the drive electrode near the edge portion of the touch panel and the drive portion is switched to conduction among the plurality of drive electrodes, the control portion is closer to the edge portion. An input device that controls the drive electrode changeover switch so that another drive electrode adjacent to the drive electrode is separated from the drive unit and the ground and switched to open.   The input device according to claim 1, wherein the control unit controls the detection electrode changeover switch so as to sequentially switch all of the plurality of detection electrodes every time the drive electrode is driven.   The input device according to claim 1, wherein a peripheral electrode connected to a ground is provided around the plurality of drive electrodes and the plurality of detection electrodes.

Images