Operation panel

Abstract

The operation panel (2) is provided with a panel member (3), a switch unit (4) which is provided on the panel member (3) and which is pressed by a user, a sensor unit (6) which detects a capacitance that changes in accordance with the positional relationship between a finger (F) of the user and the switch unit (4), and a control unit (C) into which the capacitance detected by the sensor unit (6) is input. The control unit (C) determines a contact start point at which the finger (F) of the user comes into contact with the switch unit (4) on the basis of an inflection point (56) occurring in the inputted capacitance change waveform (50), and determines that the switch unit (4) is in an operated state when the capacitance further increases from the contact start point and exceeds a predetermined value.

Description

Technical Field

[0001] The invention relates to an operation panel. Background Art

[0002] In a non-patent document (Satoru Kawai, Hisayuki Kobayashi, and Hideo Nakamura, "Changes in the skin contact area caused by the force applied by the fingertips," Bulletin of Tezukayama Junior College, Humanities, Social Sciences, Natural Sciences 31 213_a-204_a 1994-03-01), it is described that when a person presses a target part with a finger, the contact area between the finger and the target part changes exponentially with respect to the force applied by the fingertips, regardless of age or gender. As a result, the contact area between the finger and the target part increases at a predetermined rate before the finger applies a predetermined force, and any of the five fingers has a phenomenon in which the contact area increases at a predetermined rate.

[0003] Therefore, the inventor of the present application considered judging the operating state of the switch part of the operating panel by the user based on the rate of increase of the contact area, and proposed a method in which the contact area of ​​the starting point of contact of the finger on the switch part is used as a reference value, and the method judges that the finger is in an operating state when the contact area becomes a specified multiple of the reference value. Summary of the invention

[0004] However, the contact area between the finger and the switch portion varies greatly depending on the size of the finger operating the switch portion or the part of the finger used for the operation. Therefore, it is difficult to accurately determine the contact start point of the finger based on the contact area between the finger and the switch portion.

[0005] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to improve the accuracy of obtaining the contact start point of a finger without being affected by the size of the finger or the contact pattern of the finger.

[0006] An operating panel of one embodiment of the present invention includes a panel component, a switch portion, a sensor portion and a control portion, wherein the switch portion is provided on the panel component and is pressed by a user, the sensor portion detects an electrostatic capacitance that changes according to a positional relationship between a finger of the user and the switch portion, the control portion inputs the electrostatic capacitance detected by the sensor portion, and the control portion determines a contact starting point where the finger of the user contacts the switch portion based on an inflection point that appears in a waveform of a change in the input electrostatic capacitance, and when the electrostatic capacitance further increases from the contact starting point and exceeds a specified value, the control portion determines that the switch portion is in an operated state.

[0007] In the above embodiment, the electrostatic capacitance that changes according to the positional relationship between the user's finger and the switch portion changes inversely proportional to the distance from the finger to the switch portion while the finger is away from the switch portion. Therefore, as the finger approaches the switch portion, the rate of increase in electrostatic capacitance increases.

[0008] On the other hand, the electrostatic capacitance that changes according to the positional relationship between the user's finger and the switch portion changes in proportion to the contact area between the finger and the switch portion while the finger is in contact with the switch portion. In addition, the contact area between the finger and the switch portion increases in proportion to the pressing force of the finger pressing the switch portion.

[0009] Therefore, in the variation waveform of the electrostatic capacitance input from the sensor unit to the control unit, an inflection point occurs between a region where the finger approaches the switch unit and a region where the finger contacts the switch unit and applies a pressing force to the switch unit.

[0010] Therefore, the control unit determines the contact start point of the user's finger and the switch unit based on the inflection point that appears in the capacitance change waveform. Therefore, the accuracy of obtaining the finger's contact start point can be improved without being affected by the size of the operating finger or the finger's contact method.

[0011] In addition, the control unit uses the contact start point determined without being affected by the size of the operating finger or the contact method of the finger as a reference, and when the electrostatic capacitance further increases from the contact start point and exceeds a specified value, it determines that the switch unit is in an operated state. Therefore, compared with the case where the electrostatic capacitance at the contact start point, which lacks accuracy, is used as a reference value and the switch unit is determined to be operated based on the increase in electrostatic capacitance relative to the reference value, the operation of the switch unit can be accurately detected regardless of the size of the finger or the contact method. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a perspective view showing the structure of a vehicle interior component to which the operation panel according to the embodiment of the present invention is applied.

[0013] Figure 2 This is an exploded perspective view of the operation panel.

[0014] Figure 3 is a cross-sectional view illustrating the structure of a touch position sensor.

[0015] Figure 4 It is a diagram showing the change in electrostatic capacitance when the switch portion is operated with a finger, a first-order differential waveform, and a second-order differential waveform.

[0016] Figure 5 This is a flow chart related to switch determination control.

[0017] Figure 6 This is a flowchart related to switch determination control of an operation panel according to a modification. DETAILED DESCRIPTION

[0018] Hereinafter, an operation panel 2 according to an embodiment of the present invention and an instrument panel 1 as a vehicle interior component to which the operation panel 2 is applied will be described with reference to the drawings.

[0019] First, refer to Figure 1 The instrument panel 1 will be described. Figure 1 It is a perspective view showing the structure of the instrument panel 1 .

[0020] like Figure 1 As shown, the instrument panel 1 has an operation panel 2. The instrument panel 1 is provided in a vehicle cabin. The instrument panel 1 is provided in front of the vehicle cabin including the front of the driver's seat. The instrument panel 1 is provided with instruments (not shown) for displaying information of the vehicle.

[0021] Next, refer to Figures 2 to 3 The operation panel 2 will be described.

[0022] Figure 2 It is an exploded perspective view of the operation panel 2 . Figure 3 It is a cross-sectional view for explaining the structure of the touch position sensor 6 .

[0023] like Figure 2 As shown, the operation panel 2 includes a panel member 3 , a sensor module 5 , and a main body 8 .

[0024] The panel member 3 is formed in a free-form curved surface shape at least a part of which is curved. The panel member 3 is exposed in the vehicle compartment. The panel member 3 has a switch 4 as a switch portion.

[0025] The switch 4 is provided as a part of the panel member 3. The switch 4 is operated by being pressed by a user. The switch 4 includes a first switch 4a to a tenth switch 4j for operating the air conditioner (air conditioner).

[0026] The first switch 4a, the second switch 4b, the ninth switch 4i and the tenth switch 4j are switches for adjusting the temperature of the air conditioner. The third switch 4c is a switch for switching the rear defogger on / off. The fourth switch 4d is a switch for switching the front defroster on / off. The fifth switch 4e and the sixth switch 4f are switches for adjusting the air volume of the air conditioner. The seventh switch 4g is a switch for switching the automatic mode on / off. The eighth switch 4h is a switch for switching the inside and outside air.

[0027] like Figure 2 As shown, the sensor module 5 includes a sensor sheet 5 a and a touch position sensor 6 .

[0028] like Figure 3As shown, the sensor sheet 5 a is connected to a substrate unit 11 (controller C) as a control unit. The sensor sheet 5 a electrically connects the touch position sensor 6 and the substrate unit 11 .

[0029] The controller C constituting the control unit is constituted by a CPU as a processor. The controller C operates according to a program read from a memory (not shown) provided in, for example, the substrate 11 , and performs switch determination control described later.

[0030] The touch position sensor 6 is provided on the sensor sheet 5a so as to face the back surface of the panel member 3. The touch position sensor 6 is provided corresponding to each switch 4. The touch position sensor 6 detects that the user's finger F touches each switch 4. That is, the first to tenth touch position sensors 6a to 6j are provided at positions corresponding to the first to tenth switches 4a to 4j, respectively.

[0031] like Figure 3 As shown, the touch position sensor 6 is provided on the back surface of the panel member 3 corresponding to each switch 4. The touch position sensor 6 is an electrostatic capacitance type proximity sensor. The touch position sensor 6 has a plate-shaped electrode 40 arranged on the sensor sheet 5a.

[0032] The touch position sensor 6 measures the electrostatic capacitance (electrostatic capacitance value) at a cycle of, for example, 10 [ms]. The touch position sensor 6 detects the electrostatic capacitance that changes according to the positional relationship between the user's finger F and the switch 4 as a switch unit.

[0033] When the user's finger F approaches the switch 4, the electrostatic capacitance measured by the touch position sensor 6 changes with the distance from the user's finger F to the switch 4. In addition, when the user's finger F is in contact with the switch 4, the electrostatic capacitance measured by the touch position sensor 6 changes according to the contact area of ​​the user's finger F.

[0034] The electrostatic capacitance detected by the touch position sensor 6 is sent as an electric signal to the controller C (substrate unit 11 ). The controller C (substrate unit 11 ) determines which switch 4 the user's finger F has touched based on the electric signal sent from the touch position sensor 6 .

[0035] like Figure 2 As shown, the main body 8 includes a base 9, an illumination unit 10, a substrate 11, a casing 12, and a pair of solenoids 13 as vibration generating devices.

[0036] The base portion 9 is attached to the vehicle body and has a plurality of through holes formed therein for embedding the lighting portion 10 .

[0037] The lighting unit 10 is a transparent member through which light passes. A plurality of lighting units 10 are provided corresponding to the first to tenth switches 4a to 4j, respectively. The lighting unit 10 transmits light that illuminates the first to tenth switches 4a to 4j from the back.

[0038] The substrate 11 is provided between the base 9 and the housing 12. The electrical signal from the touch position sensor 6 is input to the substrate 11. The substrate 11 outputs an electrical signal corresponding to the input electrical signal to the controller C. The substrate 11 is provided with a plurality of light emitting units (not shown) for respectively illuminating the illumination unit 10. The light emitting units are composed of, for example, LEDs (light emitting diodes).

[0039] The case portion 12 is inserted into the back side of the base portion 9 and is attached to the vehicle body. The case portion 12 holds one end of the solenoid 13 .

[0040] like Figure 2 As shown, the solenoid 13 is disposed on the back side of the panel member 3. When the switch 4 is operated, the solenoid 13 vibrates the panel member 3 to generate a tactile sensation on the user's finger F. The solenoid 13 includes a coil (not shown) and a movable iron core (not shown).

[0041] When the solenoid 13 energizes the coil, the movable iron core is displaced toward the panel member 3. On the other hand, when the solenoid 13 stops energizing the coil, the movable iron core is separated from the panel member 3. Thus, the solenoid 13 vibrates the panel member 3.

[0042] One end of the solenoid 13 is held by the case portion 12. Therefore, the vibration generated by the displacement of the movable iron core can be reliably transmitted to the panel member 3.

[0043] In the operation panel 2 configured in this way, the electrostatic capacitance measured by the touch position sensor 6 changes according to the positional relationship between the user's finger F and the switch 4. The controller C determines whether the switch 4 is in an operated state or a non-operated state based on the change in electrostatic capacitance.

[0044] Next, refer to Figure 4 , the relationship between the positional relationship between the user's finger F and the switch 4 and the electrostatic capacitance detected by the touch position sensor 6 will be described. Figure 4 1 and 2 are diagrams showing changes in electrostatic capacitance when the switch 4 as a switch section is operated by a finger F, a first-order differential waveform 60 , and a second-order differential waveform 62 .

[0045] like Figure 4 As shown, the electrostatic capacitance detected by the touch position sensor 6 is expressed by the following (Formula 1).

[0046] Electrostatic capacitance = ε (S / d) ... (Formula 1) In this (Formula 1), ε represents the dielectric constant of the panel member 3 covering the touch position sensor 6. S represents the contact area between the user's finger F and the switch 4 of the panel member 3. d represents the distance from the user's finger F to the electrode 40 of the touch position sensor 6 provided on the switch 4 of the panel member 3 (hereinafter referred to as the distance d from the finger F to the switch 4).

[0047] In a state where the finger F is separated from the switch 4, the electrostatic capacitance changes inversely proportional to the distance d from the finger F to the switch 4. Therefore, as the finger F approaches the switch 4, the electrostatic capacitance becomes larger, and the increase rate increases.

[0048] On the other hand, when the finger F is in contact with the switch 4, the electrostatic capacitance changes in proportion to the contact area S between the finger F and the switch 4. The contact area S between the finger F and the switch 4 increases because the finger F is squeezed by the force of pressing the switch 4. The contact area S increases in proportion to the pressing force of the finger F pressing the switch 4.

[0049] When the user presses the switch 4 with the finger F, an inflection point 56 is generated in the temporal capacitance variation waveform 50 between an area 52 immediately before the finger F contacts the switch 4 and an area 54 where the finger F contacts the switch 4 and applies a pressing force to the switch 4 .

[0050] In addition, Figure 4 6 shows a first-order differential waveform 60 and a second-order differential waveform 62 corresponding to the change waveform 50. The first-order differential waveform 60 shows the change in the value after the first-order differential of the change in electrostatic capacitance detected by the touch position sensor 6 with respect to time. The second-order differential waveform 62 shows the change in the value after the second-order differential of the change in electrostatic capacitance detected by the touch position sensor 6 with respect to time.

[0051] The first-order differential waveform 60 reaches a maximum at the inflection point 56 of the variation waveform 50 and turns to decrease at the inflection point 56. Therefore, when the first-order differential value of the change in electrostatic capacitance detected by the touch position sensor 6 with respect to time turns to decrease, it can be determined that the inflection point 56 has appeared.

[0052] In addition, the second-order differential waveform 62 is "0" at the local maximum or local minimum of the first-order differential waveform 60. Therefore, when the value obtained by first-order differentiation of the amount of change in electrostatic capacitance detected by the touch position sensor 6 with respect to time is positive, and the value obtained by second-order differentiation of the amount of change in electrostatic capacitance with respect to time is less than "0", it can be determined that the inflection point 56 has appeared.

[0053] Here, the change waveform 50 is represented by a function (formula) obtained based on the measured value of the electrostatic capacitance measured at a predetermined period (e.g., a period of 10 [ms]) by the touch position sensor 6. As a method used to obtain this function, for example, the least square method, averaging of measured values, or a difference format can be listed.

[0054] Next, refer to Figure 5 The flowchart shown in the figure explains control related to determination of the operation state of the switch 4 (hereinafter also referred to as “switch determination control”). Figure 5 This is a flow chart related to switch determination control.

[0055] First, the symbols used in the flowchart are explained.

[0056] Tn is a Diff value calculated based on the electrostatic capacitance measured by the touch position sensor 6 at a predetermined period.

[0057] The Diff value has the relationship of "Diff value = Rawcount value - Baseline value".

[0058] The Rawcount value indicates the electrostatic capacitance (electrostatic capacitance value) obtained from the touch position sensor 6. The Rawcount value is a value that increases as the electrostatic capacitance increases when the finger F touches the switch 4. The Baseline value indicates the average value of the Rawcount value when the finger F does not touch the switch 4. The Baseline value becomes a reference value for obtaining the Diff value.

[0059] Tn changes in a predetermined cycle (eg, a cycle of 10 [ms]). Tn shown in each step of the flowchart represents a Diff value calculated based on the electrostatic capacitance measured when the step is executed.

[0060] tn represents the cycle time of periodically acquiring the electrostatic capacitance from the touch position sensor 6. Tn' represents the value obtained by first-order differentiation of the change amount of the Diff value Tn with respect to time. Tn" represents the value obtained by second-order differentiation of the change amount of the Diff value Tn with respect to time.

[0061] Next, the switch determination control will be described.

[0062] When the controller C operates according to the switch determination program read from the memory, the switch determination control process is called from the main routine and executed.

[0063] In the switch determination control process, the controller C calculates a value Tn'(tn) obtained by first-order differentiation of the change in the Diff value Tn with respect to time and a value Tn"(tn) obtained by second-order differentiation of the change in the Diff value Tn with respect to time.n ) (Step S10).

[0064] Specifically, the controller C will n -t n-1 ) within the electrostatic capacitance change amount {Tn (t n )-Tn(t n-1 )} divided by time (t n -t n-1 ), and thus obtain the value Tn' (t n ).

[0065] In addition, the controller C will obtain the value Tn' (t n ) of the change in {Tn'(t n )-Tn'(t n-1 )} divided by time (t n -t n-1 ), and thus obtain the value Tn" (t n ).

[0066] Then, the controller C determines the value Tn′ (t n ) is greater than "0" (step S12). In step S12, after determining that the first-order differential value Tn' (t n ) is below "0", the controller C repeats step S10 and step S12 until the first-order differentiated value Tn'(tn) exceeds "0". In addition, the controller C also always reads new Tn, Tn', Tn" during this period.

[0067] In step S12, the value Tn' (t n ) exceeds "0", the electrostatic capacitance increases and the finger F approaches the switch 4. Therefore, the controller C determines the value Tn" (t n ) is below "0" (step S14).

[0068] In step S14, the value Tn" (t n ) exceeds "0", the controller C repeats steps S10 to S14 until the value Tn" (t n ) becomes below "0". In addition, during this period, controller C also always reads new Tn, Tn', Tn".

[0069] In step S14, it is determined that the value Tn obtained by performing the second-order differentiation is (tn ) is below "0", it can be determined that the second-order differential waveform 62 passes through "0", and an inflection point 56 appears in the change waveform 50. Based on this inflection point 56, it can be determined that the finger F has touched the switch 4, so this point is determined as the contact start point.

[0070] In this way, the controller C obtains the inflection point 56 from the time change of the Diff value Tn indicating the value of the variation waveform 50 , and specifies the contact start point where the user's finger F contacts the switch 4 based on the inflection point 56 .

[0071] Here, in the present embodiment, the value Tn" (t n ) is compared with a comparison value of "0", but the present embodiment does not limit the comparison value to "0". For example, the value Tn (t n ) The comparison value for comparison may also have a certain amplitude. In addition, the comparison value may also be a value that is offset by a specified amount to the positive side or the negative side compared to "0".

[0072] Then, the controller C uses the latest Diff value Tn at the contact start point as the reference value T1 (step S16 ), and multiplies the reference value T1 by a predetermined coefficient α to set the open threshold Ton (step S18 ). The predetermined coefficient α multiplied by the reference value T1 is, for example, 1.4.

[0073] Next, the controller C waits until the latest Diff value Tn exceeds the on-threshold value Ton (step S20). In addition, during this period, the controller C also reads new Tn, Tn', and Tn". In step S20, when the latest Diff value Tn exceeds the on-threshold value Ton, the controller C determines that the switch 4 is in an operating state (step S22) and returns to the main routine. In addition, the fact that the switch 4 is in an operating state is stored in, for example, an operating state flag set in a memory and is used by other routines.

[0074] Thus, when the electrostatic capacitance further increases from the contact start point and exceeds the on threshold value Ton which is a predetermined value, the controller C determines that the pressing force of the switch 4 exceeds the predetermined value and the switch 4 is in the operated state.

[0075] In addition, in the present embodiment, as an example, when the pressing force when the switch 4 is pressed by the finger F reaches 4.5N, it is determined that the switch is in the operated state.

[0076] Here, it is known that no matter whether the switch 4 is pressed by the fingertip, side or fingertip of the finger F, when the Diff value Tn becomes 1.4 times or more of the Diff value Tn at the contact start point, the pressing force of the switch 4 becomes 4.5 N or more. Therefore, in step S18, the predetermined coefficient α multiplied by the reference value T1 is preferably 1.4 or more.

[0077] (Function and effect) According to the above embodiment, the following effects are achieved.

[0078] The operation panel 2 includes a panel component 3 and a switch 4 as a switch portion which is provided on the panel component 3 and is operated by a user by pressing. The operation panel 2 includes a touch position sensor 6 as a sensor for detecting electrostatic capacitance which changes according to the positional relationship between the user's finger F and the switch 4, and a controller C as a control portion to which the electrostatic capacitance (Diff value Tn) detected by the touch position sensor 6 is input. The controller C determines the contact start point where the user's finger F contacts the switch 4 based on the inflection point 56 which appears in the input electrostatic capacitance (Diff value Tn) change waveform 50. Then, when the electrostatic capacitance (Diff value Tn) further increases from the contact start point and exceeds the prescribed value (opening threshold Ton), the controller C determines that the switch 4 is in an operated operation state.

[0079] In the operation panel 2 having this structure, in the capacitance variation waveform 50 input from the touch position sensor 6 to the controller C, an inflection point 56 occurs between a region 52 where the finger F approaches the switch 4 and a region 54 where the finger F contacts the switch 4 and applies a pressing force to the switch 4 .

[0080] Therefore, the controller C obtains the inflection point 56 based on the time change of the Diff value Tn representing the value of the variation waveform 50, and determines the contact start point of the user's finger F contacting the switch 4 based on the inflection point 56. Thus, the accuracy of obtaining the contact start point of the finger F can be improved without being affected by the size of the finger F performing the operation or the contact method of the finger F.

[0081] In addition, the controller C uses the Diff value Tn corresponding to the capacity of the contact start point determined as a reference value without being affected by the size of the operating finger F or the contact method of the finger F. Then, when the Diff value Tn of the reference value further increases and exceeds the on threshold value Ton as a specified value, the controller C determines that the switch 4 is in the operated state.

[0082] Therefore, compared with using the electrostatic capacitance at the start point of contact which lacks accuracy as a reference value and determining whether the switch 4 is operated based on the increase in the electrostatic capacitance relative to the reference value, the operation of the switch 4 can be accurately detected regardless of the size of the finger F or the contact method.

[0083] In the operation panel 2 , the controller C as the control unit determines that the inflection point 56 has appeared when the first-order differential value of the input change amount of electrostatic capacitance (Diff value Tn) with respect to time is positive and the second-order differential value of the change amount with respect to time is equal to or less than “0”.

[0084] According to this configuration, the inflection point 56 appearing in the variation waveform 50 can be identified by using the first-order differential value and the second-order differential value of the variation amount of the electrostatic capacitance (Diff value Tn) with respect to time. This makes it easy to determine the inflection point 56 by the calculation process of the controller C.

[0085] In the operation panel 2 , the on threshold value Ton, which is a predetermined value, is set by multiplying the electrostatic capacitance obtained at the contact start point by a predetermined coefficient α.

[0086] According to this configuration, the on threshold value Ton, which is a predetermined value, can be simply calculated, and an increase in the load of control can be suppressed.

[0087] In addition, the on threshold value Ton for determining the operation state of the switch 4 is calculated based on the electrostatic capacitance (Diff value Tn) obtained at the contact start point. Thus, the on threshold value Ton can be determined based on the electrostatic capacitance at the contact start point that can be changed according to the size of the finger F or the contact method, so compared with the case where the on threshold value Ton is set to a fixed value, the on threshold value Ton can be set appropriately according to the size of the finger F or the contact method.

[0088] In addition, in this embodiment, the case where the operation state of the switch 4 is determined based on the latest Diff value Tn corresponding to the size of the electrostatic capacitance is described, but this embodiment is not limited to this. For example, the operation state can be determined based on the contact area between the finger F and the switch 4, and the contact area has a correlation with the electrostatic capacitance and changes according to the size of the electrostatic capacitance.

[0089] Specifically, the controller C calculates the contact area between the user's finger F and the switch 4 based on the latest Diff value Tn obtained in step S16, and uses the calculated contact area as the reference value T1. The calculation formula for calculating the contact area based on the Diff value Tn is obtained in advance through experiments or the like.

[0090] Then, the controller C multiplies the reference value T1 by a predetermined coefficient α to set an open threshold value Ton as a predetermined threshold value (step S18). Then, when the contact area calculated based on the latest Diff value Tn exceeds the open threshold value Ton (step S20), the controller C determines that the switch 4 is in an operated state (step S22).

[0091] In the operation panel 2, the controller C as the control unit calculates the contact area between the user's finger F and the switch 4 as the switch unit based on the input electrostatic capacitance. Then, when the contact area exceeds the on threshold value Ton as a predetermined threshold, the controller C determines that the electrostatic capacitance (Diff value Tn) exceeds the predetermined value.

[0092] Even in such a structure, the same effects as described above can be obtained.

[0093] In the operation panel 2 , an on threshold value Ton as a predetermined threshold value is set by multiplying a contact area obtained at a contact start point by a predetermined coefficient α.

[0094] According to this configuration, the on threshold value Ton, which is the predetermined threshold value, can be simply calculated, and an increase in the load of control can be suppressed.

[0095] In addition, the on threshold Ton for determining the operation state of the switch 4 is calculated based on the contact area obtained at the contact start point. Thus, the on threshold Ton can be determined based on the contact area of ​​the contact start point that can be changed according to the size or contact method of the finger F, so compared with the case where the on threshold Ton is a fixed value, the on threshold Ton can be set appropriately corresponding to the size or contact method of the finger F.

[0096] <Modification> Figure 6 This is a flowchart related to switch determination control of an operation panel according to a modification.

[0097] The operation panel 2 according to the modification is different from the above-described embodiment in that the switch determination control process executed by the controller C as the control unit is different, and the following description will focus on the parts that are different from the above-described switch determination control process.

[0098] When executing the switch determination control process, the controller C calculates the value Tn' (t n ) (Step SB10).

[0099] Then, the controller C determines the most recent first-order differential value Tn' (t n) minus the value obtained by the last first-order differentiation Tn' (t n-1 ) is less than "0" (step SB12). In step SB12, when the difference is greater than "0", steps SB10 and SB12 are repeated until the difference is less than "0". In addition, during this period, controller C also always reads new Tn, Tn', and Tn".

[0100] In step SB12, when the difference is less than 0, the first-order differential value decreases, and it can be determined that an inflection point 56 appears in the variation waveform 50. Based on the inflection point 56, it can be determined that the finger F has touched the switch 4, and this point is determined as the contact start point.

[0101] In this way, the controller C obtains the inflection point 56 from the time change of the Diff value Tn indicating the value of the variation waveform 50 , and specifies the contact start point where the user's finger F contacts the switch 4 based on the inflection point 56 .

[0102] Then, the controller C uses the latest Diff value Tn at the contact start point as a reference value T1 (step B14 ), and multiplies the reference value T1 by a predetermined coefficient α to set an open threshold value Ton (step SB16 ).

[0103] Next, the controller C waits until the latest Diff value Tn exceeds the on threshold value Ton (step SB18). In step SB18, when the latest Diff value Tn exceeds the on threshold value Ton, the controller C determines that the switch 4 is in an operated state (step SB20), and returns to the main routine. Thus, when the electrostatic capacitance (Diff value Tn) further increases from the contact start point and exceeds the on threshold value Ton as a predetermined value, the controller C determines that the switch 4 is in an operated state.

[0104] (Function and effect) In the operation panel 2 , the controller C as the control unit determines that the inflection point 56 has appeared when the value obtained by first-order differentiation of the input amount of change in electrostatic capacitance (Diff value Tn) with respect to time turns to decrease.

[0105] According to this configuration, by using the first-order differential value of the input variation of the electrostatic capacitance (Diff value Tn) with respect to time, it is possible to determine that the inflection point 56 appears in the variation waveform 50 , and to identify the contact start point of the finger F contacting the switch 4 .

[0106] Therefore, compared with the case where the contact start point is determined using a value obtained by first-order differentiation or second-order differentiation of the input change amount of electrostatic capacitance (Diff value Tn) with respect to time, the calculation process can be simplified and the calculation speed can be increased.

[0107] In addition, in this embodiment, the case where the operation state of the switch 4 is determined based on the latest Diff value Tn corresponding to the size of the electrostatic capacitance is described, but this embodiment is not limited to this. For example, the operation state can be determined based on the contact area between the finger F and the switch 4, and the contact area is related to the static electricity and changes according to the size of the electrostatic capacitance.

[0108] Specifically, the controller C calculates the contact area between the user's finger F and the switch 4 based on the latest Diff value Tn obtained in step SB14, and uses the calculated contact area as the reference value T1. The calculation formula for calculating the contact area based on the Diff value Tn is obtained in advance through experiments or the like.

[0109] Then, the controller C multiplies the reference value T1 by a predetermined coefficient α to set an on threshold value Ton as a predetermined threshold value (step SB16 ).

[0110] Next, when the contact area calculated based on the latest Diff value Tn exceeds the open threshold value Ton (step SB18 ), the controller C determines that the switch 4 is in the operated state (step SB20 ).

[0111] In the operation panel 2, the controller C as a control unit calculates the contact area between the user's finger F and the switch 4 as a switch unit based on the input electrostatic capacitance, and determines that the electrostatic capacitance exceeds the predetermined value when the contact area exceeds a predetermined threshold.

[0112] Even in such a structure, the same effects as those of the above-mentioned embodiment can be obtained.

[0113] The embodiments of the present invention have been described above, but the above embodiments merely illustrate a part of application examples of the present invention and are not intended to limit the technical scope of the present invention to the specific structures of the above embodiments.

[0114] In the above embodiment, the switch 4 is used as an example for operating the air conditioner, but the switch 4 may be a switch for operating a car audio system or a switch for other operations.

[0115] In the above embodiment, an example in which ten switches 4 are provided is shown. However, the number of switches 4 is not limited to this form.

[0116] In the above embodiment, an example in which the present invention is applied to the operation panel 2 provided in the instrument panel 1 is shown. However, the present invention can be applied to an input device provided in a center console or an armrest. In addition, the present invention can also be applied to operation panels provided in various devices.

[0117] This application claims priority based on Japanese Patent Application No. 2022-127663 filed with the Japan Patent Office on August 10, 2022, the entire contents of which are incorporated into this specification by reference.

Claims

1. An operation panel, wherein: It has: Panel components; A switch part, which is arranged on the panel component and is pressed by a user; a sensor portion that detects an electrostatic capacitance that changes according to a positional relationship between a user's finger and the switch portion; as well as a control unit which receives as input the electrostatic capacitance detected by the sensor unit, The control unit determining a contact start point where the user's finger contacts the switch portion based on an inflection point that appears in the inputted electrostatic capacitance change waveform, When the electrostatic capacitance further increases from the contact start point and exceeds a predetermined value, it is determined that the switch portion is in an operated state.

2. The operation panel according to claim 1, wherein: The control unit determines that the inflection point appears when a value obtained by performing a first-order differentiation of the input amount of change in electrostatic capacitance with respect to time turns to decrease.

3. The operation panel according to claim 1, wherein: The control unit determines that the inflection point has appeared when a value obtained by first-order differentiation of the input amount of change in electrostatic capacitance with respect to time is a positive value and a value obtained by second-order differentiation of the amount of change with respect to time is equal to or less than 0.

4. The operation panel according to any one of claims 1 to 3, wherein: The predetermined value is set by multiplying the electrostatic capacitance obtained at the contact start point by a predetermined coefficient.

5. The operation panel according to any one of claims 1 to 3, wherein: The control unit calculates a contact area between the user's finger and the switch unit based on the input electrostatic capacitance, and determines that the electrostatic capacitance exceeds the predetermined value when the contact area exceeds a predetermined threshold.

6. The operation panel according to claim 5, wherein: The predetermined threshold value is set by multiplying the contact area obtained at the contact start point by a predetermined coefficient.

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