JP5045023B2 - Input device - Google Patents

Description

  The present invention is designed to prevent foreign substances such as detergent from adhering even when an input device using an electrostatic switch having a high design and a waterproof structure capable of a sealed structure is installed in a kitchen or the like as an electromagnetic cooker or a water heater remote controller. It detects and makes it possible to operate the switch more reliably.

  A conventional resistive film type touch panel is formed by depositing a transparent electrode on each of the glass surface and a film provided with a gap opposite to the glass surface, and the operator presses the surface of the film with a finger or the like to make it transparent. A switch structure for detecting contact between the electrodes was adopted.

  However, in such a resistive film type touch panel, the transparent electrodes are in direct physical contact with each other, which causes deformation of the transparent electrode and changes in the contact resistance value due to changes over time such as friction. There was concern that leaks would occur.

  Therefore, in recent years, there is no movable part like a resistive touch panel, and an electrode is attached to the inside of a panel such as glass or acrylic touched by an operator and touched with a finger or the like. A capacitance change type touch panel that detects a change in capacitance has been proposed (for example, Patent Document 1).

  Such a touch panel configuration without mechanical parts matches the flow from the viewpoint of designability, such as flattening the product surface and making it easier to achieve designability and waterproof structure.

In Patent Document 1, the touch panel unit is composed of a plurality of transparent sheet electrodes in which a signal pattern and a GND pattern are printed on an ITO film on a PET film, and the control unit can measure an oscillation circuit whose frequency is variable and a waveform width. A CPU having an input capture function is provided, and a change in capacitance when an operator touches one of the plurality of transparent sheet electrodes is determined by the control unit, and the switch function and the plurality of transparent Which transparent sheet is pressed among the sheets is determined.
JP 2004-213114 A

  However, with the method of changing the capacitance, in principle, no foreign pressure is required, so that foreign substances such as detergent and water are attached to the panel surface above the electrodes. Similarly, the dielectric capacitance may change, and it may be determined that the switch has been touched.

  Especially in kitchens, baths and sanitary related products such as cooking utensils and remote controls for water heaters in the environment where generation of oil, detergents, food waste, etc. occurs, liquids such as oil, food wastes, detergents, etc. are scattered. In addition, it is an unavoidable environment to completely eliminate the case where foreign matter adheres through the operator's hand, and it has been a problem to reduce input determination errors due to the attachment of these foreign matters.

SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and in view of characteristics such as a capacitance change range and a pattern when a foreign substance such as a detergent attached to a switch part adheres and touches with a finger, one switch By properly arranging electrode groups consisting of multiple electrodes, the difference between the capacitances of each electrode group when touching with a foreign object and a finger is judged to detect the adhesion of the foreign object, and erroneous input An object of the present invention is to provide a stable input device having no problem.

  Therefore, in order to solve the conventional problem, the input device of the present invention is an input device that performs input by touching the panel with an electrostatic object such as a finger, and the input device is a switch position provided on the panel. An electrode input means having a plurality of electrode groups that are insulated from each other with a mark clearly indicating the position of the panel, and an electrostatic capacitance that detects a change in capacitance due to the proximity of the electrostatic object to the mark Switch means and determination means for detecting a touch difference by detecting a difference in the amount of change in capacitance for each of the electrode groups are provided.

  Normally, the user touches the mark of the switch portion and touches so that the overlap area of the finger to the electrode of each electrode group becomes substantially equal for each electrode group if the touch is made so that the mark position is substantially the center of the finger. The electrodes are arranged. With this arrangement, when touching with a finger, the change in capacitance for each electrode group is the same, but since foreign substances are considered to adhere randomly, there is no overlap between the electrode groups in the electrodes. It becomes equal, and the change in the capacitance for each electrode group also varies.

  Therefore, by arranging the electrodes appropriately with respect to the mark position of the switch part in this way, when there is a contact object that causes a change in capacitance such as a finger or a foreign object, the capacitance between each electrode group By detecting the difference in change, it is possible to determine whether the object is a foreign object or a finger touch.

  In this way, by disposing a plurality of electrode groups for each switch, by determining the difference in capacitance change pattern of each electrode group, it is possible to discriminate between touching with a finger and foreign matter adhering Therefore, it is possible to provide an input device that can reduce erroneous input as much as possible due to factors such as adhesion of foreign matter.

  1st invention is an input device which inputs by touching a panel with an electrostatic substance, such as a finger, and the input device includes a mark clearly indicating a switch position provided on the panel and affixed across the panel. Electrode input means having a plurality of insulated electrode groups, electrostatic switch means for detecting the amount of change in capacitance due to the proximity of the electrostatic object to the mark, and the capacitance of each electrode group Determining means for detecting the difference in the amount of change and determining the presence or absence of a touch.

  For this reason, for example, by arranging the electrode groups symmetrically, when touching with a finger having a characteristic of being touched with a substantially circular contact shape, and a foreign object with many cases attached in a random shape such as an ellipse At the time of adhesion, foreign matter adhesion can be detected by detecting a difference in the capacitance change of each electrode group, and erroneous input due to foreign matter adhesion can be prevented.

  According to a second aspect of the present invention, in the first aspect of the invention, as an electrode group of the electrode input means, an electrode group arranged at least substantially in a direction perpendicular to the direction of gravity with respect to one mark is substantially horizontal. The electrode group is arranged only in the direction.

  This makes it possible to increase the difference in capacitance change between both electrode groups by taking advantage of phenomena such as the fall of foreign matter due to gravity in an environment where there are many liquid foreign matters such as detergents. Can be detected.

  According to a third aspect of the present invention, in the first aspect of the invention, as an electrode group of the electrode input means, an electrode group disposed substantially concentrically with respect to the center of gravity of at least one mark, and an electrode group disposed substantially concentrically And an electrode group disposed on the outer periphery.

  As a result, when touching with a finger, the change in capacitance of the electrode group arranged substantially concentrically with respect to the center position is larger than that of the other, so that it adheres to an ellipse or is caused by gravity. In the case of a deformed foreign matter, the change in both electrode groups is reduced, the difference in capacitance change between the two electrode groups can be increased, and more accurate foreign matter detection is possible.

  In a fourth aspect of the invention, particularly in the first aspect of the invention, the determination means detects a difference in the amount of change in the capacitance of the electrode group, and the maximum value, the minimum value, or the variance value of the difference exceeds a predetermined threshold value. It is set as the structure which alert | reports prompting the process which cleans the part of a mark. As a result, the operator can recognize the cause of the erroneous input, and the erroneous input due to the attachment of the foreign matter is eliminated by cleaning, thereby enabling more reliable and comfortable input.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 shows an overview as an example of a product provided with an input device according to the present embodiment, and FIG. 1B shows a schematic cross-sectional view of this product taken along one-dot chain line SS ′ in FIG. The block diagram which mainly showed the part which concerns on an input device was shown in figure in relation.

  The product 11 shown in FIG. 1 forms an overview surface with a liquid crystal display device 16 and an acrylic panel 5, and an operator touches the acrylic panel 5 with a finger 10 when inputting to the input device according to the embodiment of the present invention. The switch position marks 13, 14, and 15 that clearly indicate the locations to be touched are configured, and the electrodes 6, 7, and 8 are disposed on the inside of the acrylic panel 5 of the switch position marks 13 to 15.

  Here, the acrylic panel 5 may be replaced with another material such as glass.

  The switch position marks 13, 14, 15 on the acrylic panel 5 of the product 11 are engraved to clearly indicate to the operator the range to be touched to effectively operate the three switches formed by the electrostatic switch means 9. Yes, it is formed by drawing on the acrylic panel 5 or by processing the surface to make irregularities.

  The input device in the present embodiment shown in FIG. 1 includes an electrostatic switch means 9, a control means 1, and a determination means 12.

  The electrostatic switch means 9 includes a switching circuit unit 4, an oscillation circuit unit 2, a frequency / voltage conversion circuit unit 3, and electrodes 6 to 8 surrounded by a dotted line. In the present embodiment, as an example, a case is shown in which three switches that can be independently input are configured by the electrodes 6, 7, and 8, and the number of electrodes may be increased or decreased.

  The control means 1 in FIG. 1 controls the entire input device and is composed of a microcomputer and its peripheral circuits. The control means 1 may be mounted on a microcomputer common to the control means for controlling the entire product 11.

The switching circuit unit 4 is a scan circuit that switches the connection between the oscillation circuit unit 2 and the electrodes 6, 7, and 8 in a time-sharing manner according to a signal from the control unit 1.

  The oscillation circuit unit 2 is a circuit that generates an oscillation signal at an oscillation frequency corresponding to the capacitance generated in the electrodes 6, 7, and 8 and the acrylic panel 5, and is configured using a generally known RC oscillation circuit. To do.

  The frequency / voltage conversion circuit unit 3 is a circuit that generates a voltage signal corresponding to the oscillation frequency in the oscillation circuit unit 2 and inputs the voltage signal to the control means 1. In this embodiment, the higher the oscillation frequency, the lower the voltage The lower the frequency, the higher voltage is generated, and the relationship between the frequency and the voltage after conversion is substantially inversely proportional.

  The determination unit 12 compares the voltage value input from the frequency / voltage conversion circuit unit 3 to the control unit 1 with a threshold voltage value Vth stored in advance, and determines the presence or absence of a touch based on the comparison result. In the present embodiment, the determination unit 12 mounts a determination program on the same microcomputer as a part of the control unit 1.

  The equivalent capacitance generated in each electrode and the acrylic panel 5 is increased by touching with the finger 10. This is because electric charges are induced through the human body, which can be regarded as an electrical conductor. Touching with the finger 10 lowers the oscillation frequency of the oscillation circuit unit 2, and the output voltage of the frequency / voltage conversion circuit unit 3 is It will rise.

  FIG. 2 is a graph showing an example of a change in a voltage signal input from the frequency / voltage conversion unit to the control unit in the embodiment of the present invention.

  A graph line 17 in FIG. 2 indicates a signal from the electrode 8 located inside the acrylic panel 5 of the switch position mark 15 when the finger 10 touches the position of the switch position mark 15 in the input device according to the present embodiment. These are graph lines showing an example of a change in the voltage signal V output to the control means 1 through the oscillation circuit unit 2 and the frequency / voltage conversion circuit unit 3 by the switching circuit unit 4.

  Actually, since the switching circuit unit 4 switches the connection between the electrodes 6 to 8 and the oscillation circuit unit 2 in a time-sharing manner, the output voltage signal V has a discrete value. However, in FIG. Are indicated by solid lines as continuous values interpolated.

  The vertical axis in FIG. 2 is the voltage signal V input from the frequency / voltage converter 2 to the control means 1, and the horizontal axis indicates the elapsed time T from a certain point in time. Assuming that the equivalent capacitance C of the electrode 8 is given, the capacitance C can be expressed by an equivalent expression of C = ε * S / d. In this equation, ε is the dielectric constant of the acrylic plate, d is the thickness of the acrylic plate, and S is the area where a conductor such as the finger 10 contacts the acrylic panel 5.

  FIG. 2 shows a change when the switch position mark starts to be touched at time T0 and the finger is released at time T2. The graph line 17 rises from time T0 to T2 while the finger is touching from V = Vfree, which is a voltage value shown when the finger 10 is not touching, and falls again when the finger is released at time T2. Thus, V = Vfree is returned.

  The determination means 12 in the control means 1 stores a threshold voltage Vth determined in advance based on parameters such as the size of the electrode 8, the thickness and material of the acrylic panel, and the operational feeling when touched with a finger. The threshold voltage Vth is compared with the input voltage signal V. When the voltage signal V exceeds the threshold voltage Vth and the condition V> = Vth is satisfied, it is determined that the switch has been touched. It functions.

  However, in such an input device, in principle, even when conductive foreign matter such as water or detergent adheres to the switch position mark, the output voltage from the frequency / voltage conversion circuit unit 3 rises in the same manner. There may be a case in which an erroneous input that erroneously determines that the finger is touched occurs.

  For this reason, in the present embodiment, the electrode corresponding to one switch position mark is divided into a plurality of electrically independent electrode groups (hereinafter referred to as electrode groups), and foreign matter adheres when touched with a finger. By detecting the difference in the voltage signal generation pattern due to the difference in characteristics such as the contact shape between the two cases, it is possible to determine whether the finger touch or foreign matter adheres, and to reduce the erroneous input due to the foreign matter as much as possible. To do.

  Specific examples will be described below.

  FIGS. 3 and 4 show an electrode arrangement example when the electrode 8 is divided into two electrode groups A and B, and when both electrode groups are connected to the oscillation circuit unit 2 by the switching circuit unit 4 by time-division switching. An example of the time change of the voltage signals V (A) and V (B) from the frequency / voltage conversion circuit unit 3 is shown.

  Also in this case, as in FIG. 2, the voltage signals V (A) and V (B) are actually discrete values, but are shown as continuous values.

  FIG. 3 shows an example of a case where the electrode 8 is configured by an electrode group A (electrodes shown by a dashed line) arranged substantially horizontally and an electrode group B (electrodes shown by a hatched box) arranged substantially vertically.

  Although not shown in FIG. 3, all the electrodes belonging to the same electrode group are short-circuited in parallel with each other and connected to the switching circuit unit 4. That is, the total value of equivalent capacitances of electrodes belonging to the same electrode group is connected to the oscillation circuit unit 2 via the switching circuit unit 4, and the change in capacitance when touched with a finger is also included. , Detected as the sum of electrodes belonging to the same electrode group.

  FIG. 4 is a graph showing an example of a temporal change in output voltage for each electrode group when a finger touches the electrode group and a foreign object adheres in the embodiment of the present invention.

  The graph of FIG. 4A is an example of a graph diagram in which the temporal changes of the voltage signals of both the electrode group A and the electrode group B when the operator touches with a finger are superimposed. The graph of FIG. 4 (b) in the lower stage shows the time change of the voltage signal in the case where the foreign matter adheres to the corresponding switch position mark portions of the electrode groups A and B.

  As shown in the equivalent equation C = ε * S / d of the electrode part, the change in the voltage signal is the total for each electrode group with respect to the area where the finger or the foreign substance, which is a conductive substance, is in contact with the opposite part of each electrode. Proportional to area.

  Therefore, as an example, as shown in FIG. 3, if the electrodes are arranged radially evenly with respect to the approximate center position of the switch position mark, the operator touches the center portion of the switch position marker. It is considered that a substantially circular shape is formed symmetrically at the center position so as to be surrounded by a dotted line 24 in FIG.

  Accordingly, the total area of contact with the fingers of the electrode groups A and B is substantially the same. As a result, the change in the voltage signals from the electrode groups A and B shows substantially the same change as shown in the voltage signals V (A) and V (B) in FIG. 4, and the difference between the two voltage signals becomes small. .

  However, when foreign matter or the like adheres, it may be randomly attached due to scattering, and when the product 11 is a wall-hanging type, a phenomenon such as the foreign matter dripping and moving due to gravity occurs. Therefore, it is not substantially symmetric with respect to the center of the switch position marker, and as shown by the broken line 25 in FIG. For this reason, the total contact areas of the electrode groups A and B are not substantially the same.

  For example, when a foreign substance adheres as shown by the broken line 25 in FIG. 3, as shown in FIG. 4B, the total contact area (the area in contact with the opposite position of each electrode, that is, the broken line 25 in FIG. The voltage signal V (B) of one of the electrode groups B having a large inner portion and the hatched portion of the electrode group B indicated by diagonal lines is the total contact area (that is, the overlap of the inner side of the broken line 25 and the electrode group A indicated by the broken line in FIG. Compared with the voltage signal V (A) of the other electrode group A having a small (part), it greatly changes.

  This is because the capacitance C can be expressed by an equivalent expression of C = ε * S / d, so that d corresponding to the thickness of the acrylic panel 5 and the same foreign substance, the dielectric constant ε is unchanged. This is because the change ΔC in capacitance (that is, inversely proportional to the change ΔV in the voltage signal) is proportional to the total area of overlap between the foreign matter and each electrode group.

  Therefore, in consideration of such a difference in voltage signal for each electrode group, in the present embodiment, the determination means 12 compares the voltage signals V (A) and V (B) with the threshold voltage Vth, and the voltages of both electrode groups. The absolute value ΔV = ABS (V (A) −V (B)) of the signal difference is compared with the voltage signal difference determination threshold value Vdiff of the voltage signal difference, and the voltage signal difference exceeds the voltage signal difference determination threshold value Vdiff. If it is larger, it is determined that the rise in the voltage signal is due to a foreign substance, and the input operation is canceled.

  For example, at time T1 ′ in FIG. 4A, the voltage signal difference ΔV sandwiched by the two-dot chain line satisfies the relationship ΔV ≦ Vdiff compared to the voltage signal difference determination threshold Vdiff enclosed by the one-dot chain line. It is determined that the touch is. Further, at time T1 'in FIG. 4B, since ΔV> Vdiff, it is determined as a foreign object.

  In this embodiment, frequency / voltage conversion is performed so that, for each electrode group, a simulated foreign object such as a finger or a detergent causes an equivalent voltage signal change when the total contact area of each electrode group is the same. The gain adjustment is performed by the circuit unit 3, and the voltage signal difference determination threshold value Vdiff is previously determined based on the gain adjustment and stored in the determination unit 12.

  Furthermore, when the determination unit 12 performs foreign matter determination, it is effective to perform a notification process for prompting cleaning of the acrylic panel 5 subsequently.

  Furthermore, if a foreign object attached to the fingertip adheres to and stays on the acrylic panel 5 when it touches the switch position mark, and then falls down the surface of the acrylic panel 5 according to gravity very slowly, An algorithm for canceling the input operation when the voltage remains above the threshold voltage Vth for a certain period of time or an algorithm that adaptively decreases the voltage signal difference determination threshold Vdiff over time. Even if combined, it is effective.

  In summary, the operation of determining the touch by the control unit 1 is an example of the operation of the input device when the touch of the finger and the adhesion of the foreign matter are determined from the difference in the output voltage of the electrode group in the embodiment of the present invention. This will be described with reference to the flowchart of FIG.

First, when the process is started (S31), the control unit 1 switches the connection between the electrode group A and the oscillation circuit unit 2 by the switching circuit unit 4 (S32), and from the oscillation circuit unit 2 by the frequency / voltage conversion circuit unit 3 The output voltage signal V (A) is input and stored (S33).

  Next, the control unit 1 switches the connection to the electrode group B by the switching circuit unit 4 (S34), and inputs and stores the voltage signal output from the oscillation circuit unit 2 by the frequency voltage conversion circuit unit 3 (S35).

  Next, the determination means 12 compares the voltage signal difference ΔV = ABS (V (A) −V (B)) between the voltage signals V (A) and V (B) with a predetermined voltage signal difference determination threshold Vdiff ( S36) If the voltage signal difference exceeds the determination threshold Vdiff, the acrylic panel 5 cleaning mode is activated (S40), and if the voltage signal difference is eliminated, the process returns to step S31 again.

  Here, the switch cleaning process prompts the user to wipe the acrylic panel 5 for a certain period of time, such as 30 seconds, and accepts the switch not to perform an unintended operation by touching the electrostatic switch portion for the wiping and cleaning. As a specific example, the liquid crystal display device 16 is displayed in black so that foreign matters can be easily seen, the electrode group portion to be cleaned is displayed in a different color, It is more effective to display a message such as “Wipe the part with a cloth” or to display the countdown time until the switch cleaning process is completed.

  If the voltage signal difference is smaller than the determination threshold value Vdiff in step S36, the voltage signal V (A) is compared with the touch determination threshold value Vth (S37).

  If it exceeds the determination threshold value Vth, it is determined that there is a valid switch input, and switch acceptance processing is performed (S38).

  If it falls below the determination threshold value Vth, the process returns to step S31 and continues. Actually, until the connection of the electrode group A in the next step S32, the control means 1 also sequentially determines the electrode groups of the other switch position mark portions as time division processing.

  Finally, the electrode group may be arranged as shown in FIG. For example, a substantially circular electrode group A26 (electrodes shown by hatching) and a substantially concentric electrode group B27 (electrodes shown by a broken line background) surrounding it may be arranged with respect to the center of the switch position mark. .

  When the operator touches, it is conceivable that the contact portion of the finger falls within the electrode group A26, and the voltage signal V (A) from the electrode group A rises, while the voltage signal V (B of the electrode group B17 increases. ) Is not expected to rise.

  However, when a foreign substance adheres randomly, the probability that it fits within the electrode group A26 is low, and it is considered that the probability that it adheres across the electrode group B27 is high. If (B) rises above a predetermined threshold, it is possible to use an algorithm that cancels input processing.

  In the present embodiment, an example in which two electrode groups are compared has been described. However, three or more electrode groups may be used. In this case, a method of comparing the voltage signal difference ΔV between the electrode group that maximizes the change of the voltage signal in each group and the minimum electrode group with a threshold value, variance from the average value, and standard deviation A determination method in which a value is compared with a threshold value may be applied.

  Further, in the present embodiment, a method has been described in which a change in capacitance is oscillated by an RC oscillation circuit, and a voltage value is input to the control means by the frequency / voltage conversion circuit. For example, a frequency / voltage conversion circuit is used. Of course, other frequency detection circuit configurations such as a circuit configuration in which AD is directly input by the control means and a circuit configuration in which the frequency signal is zero-crossed with respect to the DC value and input to the control means may be used.

  As described above, according to the input device according to the present invention, erroneous determination of touch of the electrostatic switch due to adhesion of a foreign object can be reduced, so that even when employed in a kitchen / sanitary related product, the operation is performed more reliably. An input device can be provided.

Overview and block diagram showing an example of a product provided with an input device according to an embodiment of the present invention The figure which shows an example of the change of the voltage signal input into a control means from the frequency and voltage conversion part in embodiment of this invention The figure which shows an example of arrangement | positioning of the electrode group in embodiment of this invention The figure which shows an example of the time change of the output voltage for every electrode group when a finger | toe touches the electrode group in embodiment of this invention, and when a foreign material adheres The flowchart which shows an example of operation | movement of an input device in the case of discriminating the touch of a finger and adhesion of a foreign material from the difference in the output voltage of the electrode group in the Example of this invention. The figure which shows another example of arrangement | positioning of the electrode group in embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Control means 2 Frequency / voltage conversion circuit part (electrostatic switch means)
3 Oscillation circuit (electrostatic switch means)
4 switching circuit (electrostatic switch means)
5 Acrylic panel (electrode input means)
6, 7, 8 Electrode group (electrode input means)
9 Electrostatic switch means 10 Finger (electrostatic substance)
12 Determination means 13, 14, 15 Mark (electrode input means)
22 Electrode group B arranged in a substantially vertical direction
23 Electrode group A arranged in a substantially horizontal direction
26 Substantially circular electrode group A (electrode group arranged in a substantially concentric circle)
27 Substantially concentric electrode group B (electrode group disposed on the outer periphery of the electrode group disposed substantially concentrically)

Claims (4)

In an input device that performs input by touching the panel with an electrostatic object such as a finger,
The input device is :
An electrode input means comprising a mark clearly indicating a switch position provided on the panel and a plurality of electrode groups insulated from each other across the panel;
Electrostatic switch means for detecting the amount of change in capacitance due to the proximity of an electrostatic object to the mark;
Determining means for determining that there is a touch if the difference in capacitance change amount for each electrode group is a predetermined value or less, and for determining that there is no touch if the difference in change amount is greater than a predetermined value. and,
An input device comprising: The electrode group of the electrode input means has at least an electrode group arranged only in a direction substantially perpendicular to the gravitational direction and an electrode group arranged only in a substantially horizontal direction with respect to one mark. The input device according to claim 1. As an electrode group of the electrode input means, an electrode group arranged in a substantially concentric circle with respect to a center of gravity position of at least one of the marks, and an electrode group arranged in an outer peripheral portion of the electrode group arranged in the substantially concentric circle The input device according to claim 1. The determination means detects a difference in capacitance change amount of the electrode group, and prompts a process of cleaning the mark portion when the maximum value, minimum value, or variance value of the difference exceeds a predetermined threshold value. The input device according to claim 1, wherein notification is performed.

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