JP2016218543A - Detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detector capable of setting a threshold in response to a detection object being in contact with an operation surface to improve detection accuracy.SOLUTION: A detector 1 includes: a threshold setting unit 16 that estimates a maximum capacitance value Dof a capacitance value D on the basis of an increased speed V of the capacitance value D representing a detection value output by a touch panel 10 regarded as a detection part in response to a detection object, as shown in Fig 1(b) and that sets a determination threshold Drepresenting a threshold for determining detection of the detection object on the basis of the maximum capacitance value D; and a control unit 18.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a detection device.

  As a conventional technique, a physical amount distribution indicating the degree of approach of the operating finger to the touch panel is measured, a hover position detecting unit that detects the hover position of the operating finger from the physical amount distribution, and the detected hover position at a predetermined distance There is known a terminal device that includes a hover position correction unit that corrects and outputs a corrected hover position after correction (see, for example, Patent Document 1).

  The hover position correction unit of this terminal device acquires a physical quantity distribution indicating the degree of proximity of the operating finger to the touch panel, predicts the size of the operating finger and the axial direction of the operating finger from the distribution, and performs the prediction. The corrected hover position is output by correcting the hover position using a coordinate correction amount determined in advance based on the size of the operating finger and a correction direction determined by the axial direction of the operating finger. The terminal device displays the key by changing the display position of the key displayed according to the hover position. The hover position indicates a position on the touch panel where the physical quantity is the maximum value.

JP 2014-92988 A

  However, in the conventional terminal device, in order to detect the hover position, it is necessary to set a threshold value lower than the threshold value for detecting the touching operation finger, and there is no plan to operate the touch panel. There is a problem that the display position of the key is changed by detecting the operation finger, and a problem that the detection accuracy is lowered due to the influence of internal noise or external noise.

  Therefore, an object of the present invention is to provide a detection device that can improve detection accuracy by setting a threshold value according to a detection target that touches an operation surface.

  According to one aspect of the present invention, the maximum detection value of the detection value is estimated based on the increasing speed of the detection value output by the detection unit according to the detection target, and the maximum threshold for determining detection of the detection target is detected. Provided is a detection device including a threshold value setting unit that is set based on a value.

  According to the present invention, it is possible to improve the detection accuracy by setting a threshold value corresponding to a detection target that touches the operation surface.

FIG. 1A is a schematic diagram of the inside of a vehicle on which the detection device according to the embodiment is mounted, and FIG. 1B is a block diagram illustrating an example of the detection device. FIG. 2A is a graph showing an example of the time change of the capacitance value D according to the embodiment, and FIG. 2B is an example of the time change of the increasing speed V of the capacitance value D. FIG. 2C is a graph of the determination threshold value set by the threshold value setting unit of the embodiment and the maximum capacitance value actually detected.

(Summary of embodiment)
The detection device according to the embodiment estimates the maximum detection value of the detection value based on the increasing speed of the detection value output by the detection unit according to the detection target, and sets a threshold value for determining the detection of the detection target. It is schematically configured with a threshold setting unit that is set based on the maximum detected value.

  Since the threshold value setting unit of the detection device can set the threshold value based on the increasing speed of the detection value that increases when the detection object touches the operation surface, the increasing speed differs for each detection object. Therefore, an appropriate threshold value can be set according to the detection target. Then, the detection device uses the threshold value set by the threshold value setting unit to determine the operation in the subsequent processing, so that the detection accuracy of the detection target is improved.

[Embodiment]
(Overall configuration of the detection apparatus 1)
FIG. 1A is a schematic diagram of the inside of a vehicle on which the detection device according to the embodiment is mounted, and FIG. 1B is a block diagram illustrating an example of the detection device. Note that, in each drawing according to the embodiment described below, the ratio between figures may be different from the actual ratio. FIG. 1B shows the flow of main signals and information by arrows.

  The detection device 1 includes, for example, a plurality of touch switches 10 as illustrated in FIG. Below, in order to simplify description, the one touch switch 10 is demonstrated.

  For example, as shown in FIG. 1A, the touch switch 10 is disposed on a center console 50 between a driver seat and a passenger seat of the vehicle 5. In the center console 50, for example, a display device 8 that functions as a display unit of an electronic device to which the detection device 1 is electrically connected is disposed. The touch switch 10 is disposed, for example, around the display device 8.

  This electronic device is, for example, a navigation device mounted on the vehicle 5, an air conditioner 7, a music playback device, a video playback device, and the like. The detection device 1 of the present embodiment is electrically connected to the air conditioner 7 as an example.

  The detection device 1 is, for example, an electrostatic capacitance type that enables an instruction to execute a function assigned to the touch switch 10 by a touch operation on the touch switch 10 with a conductive stylus pen or an operation finger as a detection target. It is a touch switch.

In addition, as illustrated in FIG. 1B, the detection device 1 has a capacitance based on the increasing speed V of the capacitance value D as a detection value output by the touch switch 10 as a detection unit according to the detection target. estimating the maximum capacitance value D _max value D, and set based on the determination threshold D _th as the threshold value for determining the detection of the detection target to the maximum capacitance value D _max threshold A setting unit 16 and a control unit 18 are provided.

(Configuration of touch switch 10)
The touch switch 10 includes a detection electrode below the operation surface 11 on which a touch operation is performed. The touch switch 10 is electrically connected to the control unit 18 and outputs a capacitance value D as shown in FIG. Note that the capacitance value D may be a value other than zero, for example, when a touch operation is not performed.

(Configuration of threshold setting unit 16)
FIG. 2A is a graph showing an example of the time change of the capacitance value D according to the embodiment, and FIG. 2B is an example of the time change of the increasing speed V of the capacitance value D. It is a graph to show.

The threshold setting unit 16 estimates the _maximum capacitance value D _max from the capacitance value D (first detection value) at the maximum value of the increasing speed V. The threshold value setting unit 16 sets a value obtained by multiplying the estimated maximum capacitance value _Dmax by a predetermined constant as the determination threshold value _Dth . Further, the threshold value setting unit 16 generates threshold value information S ₁ including information on the set determination threshold value D _th and outputs the threshold value information S ₁ to the control unit 18.

  The capacitance value D is a capacitance value output from the touch switch 10. FIG. 2A shows the change over time of the capacitance value D. FIG.

  The electrostatic capacitance value D is a convex curve that increases and decreases from when the operator's operation finger contacts the operation surface 11 of the touch switch 10 until the contact is released. The increase and decrease in the capacitance value D are related to the contact area between the operation finger and the operation surface 11.

  Specifically, in the touch operation, the operator moves the operation finger toward the operation surface 11. Then, it is detected when the operation finger approaches the operation surface 11, and the capacitance value D increases as the contact area further increases as the contact area increases, and the operation finger is moved away from the operation surface 11. Immediately before starting to lift, the maximum contact area is reached and the capacitance value D becomes the maximum value. The increasing speed V, which is the speed at which the capacitance value D increases, is a convex curve as shown in FIG.

  Next, when the operator lifts the operation finger that touches the operation surface 11 from the operation surface 11, the contact area starts to decrease. That is, the capacitance value D changes from increasing to decreasing and continues to decrease until the operating finger is no longer detected from the operation surface 11. The increasing speed V during this period becomes a downwardly convex curve as shown in FIG. By this series of touch operations, the capacitance value D becomes an upwardly convex curve as shown in FIG.

In the present embodiment, it is assumed that the shape of the capacitance value D from the increase to the maximum value is approximated to a monotonically increasing function called a sigmoid curve, and the entire curve can be approximated by a combination of sigmoid curves. One of the characteristics of an ideal sigmoid curve is that it has one inflection point, and twice the value at this inflection point is the maximum value. Specifically, twice the function value f (X _j ) at the inflection point X _j of the sigmoid curve f (X) is the maximum value of f (X).

  This inflection point is the point at which the slope of the capacitance value D curve is maximized. That is, at the point where the increase rate V of the capacitance value D changes from increase to decrease and the derivative becomes zero, that is, the maximum value, the slope of the curve of the capacitance value D becomes maximum, and the inflection point. It becomes.

Therefore, the threshold value setting unit 16 calculates the increasing speed V of the capacitance value D as shown in FIGS. 2A and 2B, and the maximum increasing speed V _{max at which the} increasing speed V becomes maximum. The value of twice the capacitance value D (t ₁ ) at time t ₁ is estimated as the maximum capacitance value D _{max of the} capacitance value D. The maximum increase of the speed V _max calculated may be determined from a comparison of the increase in velocity V, it may be determined by a differential value.

Next, the threshold value setting unit 16 multiplies the estimated maximum capacitance value _Dmax by a constant k to calculate a determination threshold value _Dth . The constant k, since the determination threshold _{D th} is set smaller than the maximum capacitance value _{D max,} as an example, is 0 <k ≦ 2.0. Since the determination threshold _{D th} is it is better a value close to the maximum capacitance value _{D max,} as an example, and more preferably 1.0 <k ≦ 2.0.

The constant k is preferably a value close to 2, but the waveform asymmetry and variation in the shape of the capacitance value D caused by the movement of the operating finger during operation, noise generated from the inside, and external noise If the constant k is set to a certain value or more due to the influence of the above, etc., the determination threshold value _Dth becomes larger than the actually detected maximum capacitance value _Dmax , and the determination accuracy may be lowered. As a result of the experiment, the maximum constant k that suppresses the decrease in determination accuracy was approximately 1.7, and as an example, it is more preferable that 1.0 <k ≦ 1.7.

Hereinafter, as an example, an experiment regarding the determination threshold value D _th and the maximum capacitance value D _max when the constant k is 1.7 will be described.

About Experiment FIG. 2C is a graph of the determination threshold value set by the threshold value setting unit of the embodiment and the maximum capacitance value actually detected. FIG. 2C shows a graph of the determination threshold value set by the above-described method and the actually detected maximum capacitance value for each of the stylus pen, the little finger, the index finger, the thumb, and the palm. . In addition, the vertical axis | shaft of FIG.

In this experiment, a touch operation was performed with a stylus pen, little finger, index finger, thumb, and palm, and the determination threshold value D _th was calculated from the estimation of the _maximum capacitance value D _max . The diameter of the stylus pen was 6.5 mm, the diameter of the little finger was 15 mm, the diameter of the index finger was 17 mm, and the diameter of the thumb was 22 mm. In addition, an experiment was performed so that the side surface of the palm was in contact with the operation surface, and the side surface of the palm was 25 mm × 60 mm.

The calculation of the determination threshold value D _th and the measurement of the _maximum capacitance value D _max are performed 10 times for each detection target, and the average and the variation (standard deviation) from the average are shown in FIG.

Here, for example, the determination threshold D _th is, in accordance with the index finger of the frequency is estimated to be high to use, if it has been secured to the decision threshold D _th of the index finger of FIG. 2 (c), the contact area Although the contact of the thumb or palm larger than the index finger can be determined, the little finger or stylus pen having a small contact area is not detected. Similarly, when the determination threshold value _Dth is set assuming a male index finger, there is a possibility that a woman is finer even with the same index finger, or a male is less than expected due to individual differences and may not be determined.

  In addition, when the determination threshold is set according to a detection target having a small contact area such as a stylus pen, ideally a detection target having a contact area larger than that of the stylus pen can be detected. There is a possibility that floating finger detection will occur before touching the screen, resulting in reduced operability, and the possibility of being affected by electromagnetic noise such as internal noise and external noise, which may reduce the judgment accuracy. is there.

As shown in FIG. 2C, the threshold setting unit 16 of the present embodiment determines that the detection target is close to the maximum capacitance value D _max even if the contact area of the detection target changes. Since the threshold value _Dth is set, it is possible to detect a detection target with high accuracy.

The threshold value setting unit 16 sets the determination threshold value D _th from the maximum capacitance value D _max estimated after the time t ₁ , for example, as shown in FIG. Thus the control unit 18, when the capacitance value D exceeds the determination threshold D _th at time t ₂ later it is possible to determine the touch operation.

The determination threshold value D _th is set as an example at the time of the first operation after the power of the vehicle 5 is turned on, and the set determination threshold value D _th is the touch operation until the power is turned off. Used for judgment. As a modification, the threshold setting unit 16 has a threshold for starting the setting, and when the capacitance value D exceeds the threshold, the determination threshold D _th is set. It may be configured to do.

(Configuration of control unit 18)
The control unit 18 includes, for example, a CPU (Central Processing Unit) that performs operations and processes on acquired data according to a stored program, a RAM (Random Access Memory) 180 that is a semiconductor memory, a ROM (Read Only Memory), and the like. It is a microcomputer configured. In this ROM, for example, a program for operating the control unit 18 is stored. Further, the control unit 18 has means for generating a clock signal therein, and operates based on this clock signal.

The RAM 180 is used as a storage area for temporarily storing calculation results and the like, for example. In addition, the RAM 180 stores the determination threshold value D _th set by the threshold value setting unit 16.

The control unit 18 stores the determination threshold value D _th in the RAM 180 based on the threshold value information S ₁ acquired from the threshold value setting unit 16, and determines the capacitance value D acquired from the touch switch 10 as the threshold value. It is determined whether or not a touch operation has been performed by comparing the value _Dth .

Control unit 18, if the acquired electrostatic capacitance value D exceeds the determination threshold D _th, and outputs the operation information S ₂ that the touch operation has been performed. The electronic device performs a like function assigned to the touch switch 10 based on the operation information S ₂ acquired.

  Below, operation | movement of the detection apparatus 1 of this Embodiment is demonstrated.

(Operation)
When the power of the vehicle 5 is turned on, the control unit 18 of the detection apparatus 1 acquires the capacitance value D output from the touch switch 10 and outputs it to the threshold setting unit 16.

  The threshold setting unit 16 calculates the increasing speed V of the capacitance value D based on the acquired capacitance value D. When the touch operation is not performed, the calculated increase speed V is zero.

The threshold setting unit 16 obtains the maximum increase speed V _max from the increase speed V calculated based on the capacitance D that increases as a result of the touch operation.

The threshold value setting unit 16 calculates the determination threshold value D _th by multiplying the capacitance value D at the time when the obtained maximum increase speed V _max is obtained by a constant k, and the threshold value information S ₁ is obtained. Output to the control unit 18.

Control unit 18 stores the determined threshold _{D th} based on the threshold information _{S 1} acquired in RAM 180, determines a touch operation by comparing the judgment threshold _{D th} the capacitance value D .

(Effect of embodiment)
The detection device 1 according to the present embodiment can improve the detection accuracy by setting the determination threshold value _Dth corresponding to the detection target that has touched the operation surface 11. Specifically, the threshold value setting unit 16 of the detection device 1 sets the determination threshold value D _th based on the increasing speed V of the capacitance value D that increases when the detection target touches the operation surface 11. Therefore, it is possible to set an appropriate determination threshold value D _th according to the detection target that has touched the operation surface 11. Since the control unit 18 determines the operation using the determination threshold value _Dth set by the threshold value setting unit 16, the detection accuracy of the detection target is improved.

Since the detection apparatus 1 does not need to lower the threshold value in order to increase the detection accuracy of the touch operation with a stylus pen having a different contact area or an operation finger of various sizes, the touch operation can be performed before contacting the operation surface. The problem that the operability is deteriorated by the determination is suppressed, and the operability is improved. Moreover, since the detection apparatus 1 can set an appropriate determination threshold value _Dth according to the detection target that has touched the operation surface 11, internal noise, external noise, and the like caused by setting the threshold value low can be set. It is less affected and improves the detection accuracy of touch operations.

Since the determination threshold value _Dth is set based on the obtained capacitance value D, the detection device 1 is not detected unless the threshold value is low, such as when the operator is wearing a glove. Even if it is a target, an appropriate determination threshold value _Dth can be set, and detection accuracy is improved.

Since the detection apparatus 1 can set the determination threshold value _Dth before reaching the _maximum capacitance value _Dmax , it can be compared with the case where the determination threshold value is set based on the maximum capacitance value. It is possible to speed up the touch operation determination process.

  As a modification, the detection device 1 is not limited to the touch switch described above, and can be configured using a detection unit that outputs a detection value whose waveform can be approximately regarded as a sigmoid curve. Therefore, the detection unit is preferably used for a touch pad such as a capacitance method that detects an operation performed on the operation surface with a plurality of intersecting electrodes under the operation surface, a pressure sensor that detects a pressure for pressing the operation surface, and the like. Can do.

  The detection device 1 according to the above-described embodiment and modification, for example, partly by a program executed by a computer, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or the like depending on the application. It may be realized.

  As mentioned above, although some embodiment and modification of this invention were demonstrated, these embodiment and modification are only examples, and do not limit the invention based on a claim. These novel embodiments and modifications can be implemented in various other forms, and various omissions, replacements, changes, and the like can be made without departing from the scope of the present invention. In addition, not all combinations of features described in these embodiments and modifications are necessarily essential to the means for solving the problems of the invention. Furthermore, these embodiments and modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Detection apparatus 5 ... Vehicle 7 ... Air conditioning apparatus 8 ... Display apparatus 10 ... Touch switch 11 ... Operation surface 16 ... Threshold value setting part 18 ... Control part 50 ... Center console 120 ... Operation surface 180 ... RAM

Claims (4)

  The maximum detection value of the detection value is estimated based on the increasing speed of the detection value output by the detection unit according to the detection target, and a threshold value for determining the detection of the detection target is determined based on the maximum detection value. A detection apparatus including a threshold setting unit for setting. The threshold setting unit estimates the maximum detection value from a first detection value at the maximum value of the increase speed;
The detection device according to claim 1. The threshold value setting unit sets a value obtained by multiplying the maximum detection value obtained by estimation by a predetermined constant as the threshold value.
The detection device according to claim 2. The threshold value setting unit estimates a value twice the first detection value at the maximum value of the increase speed as the maximum detection value of the detection value;
The detection device according to claim 2 or 3.

Images