Proximity switch

Abstract

To provide a proximity switch that does not spoil its appearance by electrodes.SOLUTION: A proximity switch (1) comprises a first electrode part (100) and a second electrode part (200) which vary in capacitance as an object (OB) approaches, and a light source (500). The first electrode part (100) and second electrode part (200) are arranged across a detection region (AD1) where the proximity switch (1) should detect the object (OB) approaching. The light source (500) is so arranged to emit light (EL) to outside the proximity switch (1) through the detection region (AD1). A control part (900) changes an illumination state of the light source (500) when detection conditions are met (S500: Yes) including conditions that the first electrode part (100) varies in capacitance by more than a first threshold (ΔCth1) and the second electrode part (200) varies in capacitance by more than a second threshold (ΔCth2).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to proximity switches. [Background technology]

[0002] Conventionally, there are touch switches equipped with a light source. The touch switch of Patent Document 1 includes a circuit board equipped with a light source, an electrode plate, and a display sheet. The circuit board, electrode plate, and display sheet are arranged in that order from the inside to the outside of the touch switch. Characters and figures are printed on the display sheet. The electrode plate is made of a conductive material that does not transmit light. The electrode plate has a mesh-like shape. The circuit board includes a detection circuit that detects a change in electrostatic capacitance between the electrode plate and the ground, and a control circuit that controls the light source.

[0003] When a user's finger touches or approaches a touch switch, the capacitance between the electrode plate and ground changes. The detection circuit detects this change in capacitance and sends a detection signal to the control circuit. The control circuit receives the detection signal and turns on the light source. The light from the light source passes through the mesh-shaped openings in the electrode plate and illuminates the display sheet. As a result, letters and figures are displayed on the display sheet. The user can tell that the switch has been operated by looking at the display. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2006-196395 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the touch switch described in Patent Document 1 is applied to, for example, a map lamp of an automobile, if the electrode plate is covered with a transparent material instead of a display sheet on which characters or figures are displayed, the following problem occurs. That is, the mesh-shaped electrode plate becomes visible from the outside of the touch switch. As a result, the aesthetic appearance of the touch switch is impaired.

[0006] The inventors of the present application have investigated a technique for making the mesh-like electrode plate less visible by covering the electrode plate with a semi-transparent material instead of a transparent one. However, in such an embodiment, the light from the light source is reflected and diffused in unspecified directions, making it impossible to control the emission direction of the light emitted from the light source to a desired direction.

[0007] The inventors of the present application have considered a technique for detecting an object in an area where no electrodes are present and where the electrodes are not visible by expanding the detection range to a range far beyond the range where the electrodes are present. However, in such an embodiment, a signal indicating that an object has been detected is issued even when the object is present in a range where the presence of the object should not be detected, such as a region located on the opposite side of the detection region from the electrodes. [Means for solving the problem]

[0008] The present disclosure can be realized in the following forms.

[0009] (1) According to one embodiment of the present disclosure, there is provided a proximity switch for detecting the approach of an object. The proximity switch includes a first electrode portion that changes a capacitance as an object approaches, a second electrode portion that changes a capacitance as an object approaches, a light source capable of emitting light, and a control unit. The first electrode portion and the second electrode portion are arranged on either side of a detection area in which the proximity switch should detect the approach of an object, and the light source is arranged to emit light through the detection area to the outside of the proximity switch, and the control unit performs at least one of a process of changing a lighting state of the light source and a process of outputting a detection signal to the outside of the proximity switch when a detection condition is satisfied, the detection condition including a change in capacitance of the first electrode portion exceeding a first threshold value and a change in capacitance of the second electrode portion exceeding a second threshold value is satisfied. In this embodiment, when an object approaches the detection area, at least one of a process of changing the lighting state of the light source and a process of outputting a detection signal to the outside is performed. The first electrode portion and the second electrode portion are not arranged in the detection area. Therefore, the first electrode portion and the second electrode portion do not spoil the aesthetic appearance of the detection area through which light passes. In addition, since there is no need to arrange a translucent member in the detection area to hide the first electrode portion and the second electrode portion, the emission direction of the light emitted from the light source can be set to any direction to configure the proximity switch. (2) In the proximity switch of the above form, the switch may be provided with a third electrode portion that changes capacitance as an object approaches, the first electrode portion, the second electrode portion, and the third electrode portion are connected to the control portion, the third electrode portion is arranged at a position between the detection area and the control portion that is closer to the control portion, and the detection condition may include that the amount of change in capacitance of the third electrode portion is less than a third threshold value. In such an embodiment, when an object approaches outside the detection area and near the conductor connecting the first electrode portion and the control portion and the conductor connecting the second electrode portion and the control portion, it is possible to prevent the control portion from changing the lighting state of the light source and outputting a detection signal outside the proximity switch. (3) In the proximity switch of the above embodiment, the third electrode portion may be arranged on the side of the control portion on which the detection area is located, between a conductor connecting the first electrode portion and the control portion and a conductor connecting the second electrode portion and the control portion. In such an embodiment, when an object approaches between the conductor connecting the first electrode portion and the control portion and the conductor connecting the second electrode portion and the control portion outside the detection area, it is possible to more accurately prevent the control portion from changing the lighting state of the light source or outputting a detection signal outside the proximity switch. (4) In the proximity switch of the above-described form, an embodiment may be adopted in which a light-transmitting plate is provided between at least a portion of the detection area and the light source and capable of transmitting light from the light source. By adopting such an embodiment, it is possible to prevent a situation in which an object approaches the proximity switch and hits the light source, while maintaining the light emitting function of the proximity switch using the light source. (5) In the proximity switch of the above aspect, the light-transmitting plate may have projections and recesses, and the projections and recesses cause the light received from the light source to be emitted in a direction within a predetermined range. In such an embodiment, the emission direction of the light emitted from the light source can be controlled to any desired direction by appropriately configuring the unevenness of the light-transmitting plate. (6) In the proximity switch of the above aspect, the first threshold value and the second threshold value may be different values. In such an embodiment, by appropriately setting the first threshold value and the second threshold value, a position at which the approach of an object can be detected with high sensitivity can be set at any position between the first electrode unit and the second electrode unit. The present disclosure may be realized in various forms other than a proximity switch, such as a display, an overhead console, a manufacturing method for a proximity switch, a display, and an overhead console, a control method thereof, a design method thereof, a computer program for realizing the control method thereof, a non-transitory recording medium on which the computer program is recorded, etc. [Brief description of the drawings]

[0010] [Figure 1] 1 is an explanatory diagram showing a configuration of a proximity switch 1 according to a first embodiment of the present disclosure. [Diagram 2] 2 is an explanatory diagram showing the configuration of the proximity switch 1 when viewed from a different direction than FIG. 1. [Diagram 3] 2 is a diagram showing the electrical connection relationship between a first electrode section 100, a second electrode section 200, and a control section 900. FIG. [Figure 4] 1 is an explanatory diagram showing a graph illustrating changes in the capacitance C10 of the first electrode section 100 and the capacitance C20 of the second electrode section 200 according to the position Pob of the object OB. FIG. [Diagram 5] 10 is a flowchart showing a process performed when the proximity switch 1 detects the approach of an object OB. [Figure 6] 11 is an explanatory diagram showing the configuration of a proximity switch 1B according to a second embodiment of the present disclosure. FIG. [Figure 7] 2 is a diagram showing the electrical connection relationship between a first electrode section 100, a second electrode section 200, a third electrode section 300, and a control section 900. FIG. [Figure 8] 5 is a graph showing the change in capacitance C30 of the third electrode portion 300 according to the position Pob2 of the object OB added to the graph of FIG. [Figure 9] 13 is a flowchart showing a process in which the proximity switch 1B detects the approach of an object OB. [Figure 10] 10 is an explanatory diagram showing a graph illustrating changes in the capacitance C10 of the first electrode section 100 and the capacitance C23 of the second electrode section 200 according to the position Pob of the object OB. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] A. First embodiment: FIG. 1 is an explanatory diagram showing a configuration of a proximity switch 1 as a first embodiment of the present disclosure. FIG. 1 does not accurately show the shape and dimensions of each component of the proximity switch 1. The proximity switch 1 of the first embodiment detects the approach of an object OB to the proximity switch 1 and changes the lighting state of the proximity switch 1. More specifically, the proximity switch 1 detects the approach of a user's finger as the object OB and switches the proximity switch 1 on and off. Specifically, the proximity switch 1 is a map lamp disposed on the ceiling of the passenger compartment of an automobile at a position between the driver's seat and the passenger seat. The proximity switch 1 includes a first electrode unit 100, a second electrode unit 200, a light source 500, a cover 600, and a control unit 900. In order to facilitate understanding of the technology, the light source 500 is not shown in FIG. 1.

[0012] The first electrode unit 100 changes its capacitance as the object OB approaches (see the upper left part of FIG. 1). The first electrode unit 100 functions alone as a capacitance-type projection-type proximity switch. The first electrode unit 100 is a self-capacitance type proximity switch. The first electrode unit 100 includes a plurality of electrodes and a detection circuit. The detection circuit detects an increase in capacitance between the electrodes of the first electrode unit 100 and the object due to the object approaching, and outputs a signal to the outside of the first electrode unit 100. The first electrode unit 100 has a substantially rectangular plate-like outer shape. The first electrode unit 100 and the control unit 900 are connected by a conductor L10.

[0013] The second electrode unit 200 changes its capacitance as the object OB approaches (see the upper right part of FIG. 1). The configuration and function of the second electrode unit 200 are the same as those of the first electrode unit 100. The second electrode unit 200 and the control unit 900 are connected by a conductor L20. The conductor L10 and the conductor L20 are connected to the control unit 900 on the side of the control unit 900 where the detection area AD1 of the proximity switch 1 is located (see the lower center part of FIG. 1). The detection area AD1 of the proximity switch 1 will be described later.

[0014] The first electrode unit 100 and the second electrode unit 200 are arranged on either side of a detection area AD1 (see the upper part of FIG. 1). The detection area AD1 is an area where the proximity switch 1 should detect the approach of an object OB. The detection area AD1 is a substantially rectangular area defined as a specification of the proximity sensor 1. However, an area AD0 where the proximity switch 1 can actually detect the approach of an object OB includes the detection area AD1 and is a larger area than the detection area AD1 (see the center of the upper part of FIG. 1). When viewed from a direction perpendicular to the plate-shaped first electrode unit 100 and second electrode unit 200, the area where the first electrode unit 100 is arranged and the area where the second electrode unit 200 is arranged do not overlap with the detection area AD1 (see the upper part of FIG. 1).

[0015] FIG. 2 is an explanatory diagram showing the configuration of the proximity switch 1 when viewed from a different direction than FIG. 1. FIG. 2 does not accurately show the shape and dimensions of each component of the proximity switch 1. The light source 500 can emit light EL (see the lower part of FIG. 2). The light source 500 is turned on and off by being controlled by the control unit 900 based on signals from the first electrode unit 100 and the second electrode unit 200. The light source 500 is a light-emitting diode (LED). The light source 500 is arranged to emit light EL to the outside of the proximity switch 1 through the detection area AD1.

[0016] The cover 600 covers the first electrode unit 100, the second electrode unit 200, and the light source 500 (see FIG. 1). As a result, the first electrode unit 100, the second electrode unit 200, and the light source 500 are not visible from the outside. The cover 600 includes a shielding unit 610 and a light-transmitting plate 620.

[0017] The shielding portion 610 covers the first electrode portion 100, the second electrode portion 200, the conductor L10, and the conductor L20. The shielding portion 610 is made of an opaque material. As a result, the first electrode portion 100, the second electrode portion 200, the conductor L10, and the conductor L20 are not visible from the outside. The control portion 900 is covered by a member different from the cover 600 so as not to be visible from the outside. The control portion 900 is disposed inside the interior of the automobile.

[0018] The light-transmitting plate 620 is disposed between the detection area AD1 and the light source 500 (see the upper center of FIG. 1 and the center of FIG. 2). The light-transmitting plate 620 is a substantially rectangular plate-like member having four corners C111, C112, C211, and C212. The light-transmitting plate 620 and the plate-like first electrode section 100 and second electrode section 200 are disposed in parallel. When viewed from a direction perpendicular to the plate-like first electrode section 100 and second electrode section 200, the area occupied by the light-transmitting plate 620 coincides with the detection area AD1. The light-transmitting plate 620 can transmit light EL from the light source 500. The light-transmitting plate 620 is made of a transparent material. More specifically, the light-transmitting plate 620 is made of acrylic.

[0019] With this configuration, the light emitting function of the proximity switch 1 by the light source 500 can be maintained, and a situation in which the object OB approaches the proximity switch 1 and collides with the light source 500 can be prevented.

[0020] The light-transmitting plate 620 has a smooth surface (see the upper part of FIG. 2). The surface of the light-transmitting plate 620 is the side opposite to the side on which the light source 500 is disposed with respect to the light-transmitting plate 620. The light-transmitting plate 620 has irregularities 622. The irregularities 622 are provided on the back surface of the light-transmitting plate 620. The irregularities 622 can be configured as, for example, convex portions, concave portions, or an interface where two surfaces face each other. Due to the irregularities 622 provided on the light-transmitting plate 620, the light source 500 is not visible from the outside through the light-transmitting plate 620.

[0021] The light-transmitting plate 620 refracts and reflects the light EL received from the light source 500 by the unevenness 622, and emits the light in a direction within a predetermined range. The light emitted from the light-transmitting plate 620 is shown as light ELc in Fig. 2. Note that, to facilitate understanding of the technology, the unevenness 622 is not shown in Fig. 1.

[0022] In the proximity switch 1 of this embodiment, by appropriately configuring the unevenness 622 of the light-transmitting plate 620, the emission direction of the light ELc emitted from the light source 500 can be controlled to any direction.

[0023] 3 is a diagram showing the electrical connection relationship between the first electrode unit 100, the second electrode unit 200, and the control unit 900. The control unit 900 controls the proximity switch 1. The control unit 900 has a power supply terminal VDD and a ground terminal GND. The control unit 900 is an integrated circuit (IC) that operates by receiving power from a power supply via the power supply terminal VDD.

[0024] The control unit 900 is connected to the first electrode unit 100 by a conductor L10. The conductor L10 has a resistor R10. The control unit 900 is connected to the second electrode unit 200 by a conductor L20. The conductor L20 has a resistor R20. The resistors R10 and R20 reduce noise that may be included in the signal voltages from the first electrode unit 100 and the second electrode unit 200.

[0025] Fig. 4 is an explanatory diagram showing a graph illustrating changes in the capacitance C10 of the first electrode unit 100 and the capacitance C20 of the second electrode unit 200 according to the position Pob of the object OB. The lower part of Fig. 4 shows the first electrode unit 100, the second electrode unit 200, and the cover 600 in correspondence with the horizontal axis of the graph shown in the upper part of Fig. 4. Fig. 4 does not accurately represent the shapes and dimensions of each component of the proximity switch 1.

[0026] The capacitance of the first electrode unit 100 is shown by graph C10 in Fig. 4. Graph C10 shows the change in capacitance of the first electrode unit 100 when a finger as an object OB is moved in direction DL along the edges of the first electrode unit 100, the light-transmitting plate 620, and the second electrode unit 200 in direction DP (see arrow Ao0 in Figs. 1 and 3). The direction DL is the direction in which the first electrode unit 100 and the second electrode unit 200 are aligned. The direction DP is perpendicular to the direction DL.

[0027] The capacitance C10 of the first electrode unit 100 becomes a maximum value C1max when the finger is closest to the center of the first electrode unit 100. When the finger as the object OB is separated from the first electrode unit 100 by a predetermined distance or more, the capacitance C10 of the first electrode unit 100 becomes a substantially constant value C1min.

[0028] The capacitance of the second electrode unit 200 is shown by graph C20 in Fig. 4. Graph C20 represents a change in the capacitance of the second electrode unit 200 when a finger as an object OB is moved in direction DL along the edges of the first electrode unit 100, the light-transmitting plate 620, and the second electrode unit 200 in direction DP (see arrow Ao0 in Figs. 1 and 3).

[0029] The capacitance C20 of the second electrode unit 200 becomes a maximum value C2max when the finger is closest to the center of the second electrode unit 200. When the finger as the object OB is separated from the second electrode unit 200 by a predetermined distance or more, the capacitance C20 of the second electrode unit 200 becomes a substantially constant value C2min.

[0030] In this embodiment, the maximum value C2max of the capacitance C20 is the same as the maximum value C1max of the capacitance C10. These capacitances C1max and C2max are also written as Cmax (see the upper left part of FIG. 4). When a finger as the object OB is separated from the second electrode unit 200 by a predetermined distance or more, the constant value C2min of the capacitance C20 of the second electrode unit 200 is the same as the constant value C1min of the capacitance C10 of the first electrode unit 100 when the finger is separated from the first electrode unit 100 by a predetermined distance or more. These capacitances C1min and C2min are also written as Cmin (see the middle left part of FIG. 4). Cmin can be considered as the capacitance of the first electrode unit 100 and the second electrode unit 200 when the object OB is at an infinite distance relative to the proximity switch 1. In this embodiment, the first electrode section 100 and the second electrode section 200 are configured so that the graphs C10 and C20 of the change in capacitance are symmetrical with respect to the center position P0 of the detection area AD1 in the direction DL.

[0031] Fig. 5 is a flowchart showing the process when the proximity switch 1 detects the approach of an object OB. The process in Fig. 5 is executed by the control unit 900 as a processor (see the lower part of Fig. 1). The process in Fig. 5 is repeatedly executed while the main switch of the automobile in which the proximity switch 1 is mounted is turned ON.

[0032] In step S100, the capacitance C10 of the first electrode unit 100 is measured (see the upper part of FIG. 4). In step S200, the capacitance C20 of the second electrode unit 200 is measured. As can be seen from the upper part of FIG. 4, the capacitance C10 of the first electrode unit 100 and the capacitance C20 of the second electrode unit 200 are correlated with the position Pob of the object OB.

[0033] In step S500, it is determined whether or not the capacitance C10 of the first electrode unit 100 and the capacitance C20 of the second electrode unit 200 are both equal to or greater than the threshold value Cth0.

[0034] The threshold value Cth0 is set to a value smaller than the maximum capacitance Cmax (see the upper left part of FIG. 4). That is, the threshold value Cth0 is set to a value smaller than the maximum capacitance C1max, i.e., Cmax, between the finger as the object OB and the first electrode unit 100. The threshold value Cth0 is set to a value smaller than the maximum capacitance C2max, i.e., Cmax, between the finger as the object OB and the second electrode unit 200.

[0035] The threshold value Cth0 is set to a value larger than the minimum capacitance Cmin (see the middle left part of FIG. 4). That is, the threshold value Cth0 is set to a value larger than the above-mentioned constant value C1min that the capacitance C10 of the first electrode unit 100 takes when the finger as the object OB is separated from the first electrode unit 100 by more than the above-mentioned predetermined distance. The threshold value Cth0 is set to a value larger than the above-mentioned constant value C2min that the capacitance C20 of the second electrode unit 200 takes when the finger as the object OB is separated from the second electrode unit 200 by more than the above-mentioned predetermined distance.

[0036] In this embodiment, the threshold Cth0 is set as follows based on a measurement of capacitance performed in advance. The threshold Cth0 is a value that the capacitance C20 of the second electrode unit 200 takes when a finger as the object OB is present at a position P21 directly above a corner C211 of the light-transmitting plate 620 at an end of the light-transmitting plate 620 in the direction DL that is closer to the first electrode unit 100 out of the first electrode unit 100 and the second electrode unit 200 (see the center of FIG. 4). At the same time, the threshold Cth0 is a value that the capacitance C10 of the first electrode unit 100 takes when a finger as the object OB is present at a position P12 directly above a corner C111 of the light-transmitting plate 620 at an end of the light-transmitting plate 620 in the direction DL that is closer to the second electrode unit 200 out of the first electrode unit 100 and the second electrode unit 200 (see the center of FIG. 4).

[0037] When the capacitance C10 of the first electrode unit 100 is equal to or greater than the threshold Cth0, it can be assumed that a finger is present as the object OB between positions P11 and P12 in Fig. 4 (see the middle left part of Fig. 4). When the capacitance C20 of the second electrode unit 200 is equal to or greater than the threshold Cth0, it can be assumed that a finger is present as the object OB between positions P21 and P22 in Fig. 4 (see the middle right part of Fig. 4).

[0038] When the capacitance of the first electrode unit 100 and the capacitance of the second electrode unit 200 are both equal to or greater than the threshold value Cth0, it can be inferred that a finger, as the object OB, is present within a section Rad1 between positions P21 and P12 in Fig. 4 (see the upper center of Fig. 4). In other words, the section Rad1 between positions P21 and P12 is a range in which a detection area AD1 exists in the horizontal axis direction in Fig. 4, i.e., in the direction DL (see the lower center of Fig. 4).

[0039] As described above, the graph in the upper part of Fig. 4 shows the change in capacitance of the first electrode unit 100 when a finger as the object OB is moved along the edges of the first electrode unit 100, the light-transmitting plate 620, and the second electrode unit 200 in the direction DP (see arrow Ao0 in Fig. 3). When the finger as the object OB is positioned closer to the center of the first electrode unit 100 and the second electrode unit 200 in the direction DP, the capacitance of the first electrode unit 100 becomes a larger value than that of graph C10 in Fig. 4 (arrow Ao1 in Fig. 1). The capacitance of the second electrode unit 200 also becomes a larger value than that of graph C20 in Fig. 4.

[0040] For this reason, in step S500, when the capacitance of the first electrode unit 100 and the capacitance of the second electrode unit 200 are both equal to or greater than the threshold value Cth0, it can be inferred that a finger as the object OB is present within an area AD0 that encompasses the four corners C211, C111, C212, and C112 of the rectangular light-transmitting plate 620 (see the upper center part of FIG. 1).

[0041] The detection sensitivity of the object OB is minimal at the center position P0 of the detection area AD1 in the direction DL. Therefore, in the direction perpendicular to the light-transmitting plate 620, the distance at which the object OB can be detected is also minimal at the center position P0 (see AD1 in FIG. 2).

[0042] In step S500, if at least one of the capacitance of the first electrode unit 100 and the capacitance of the second electrode unit 200 is less than the threshold value Cth0, the process proceeds to step S600. If both the capacitance of the first electrode unit 100 and the capacitance of the second electrode unit 200 are equal to or greater than the threshold value Cth0, the process proceeds to step S700.

[0043] The process of step S600 is executed when the proximity switch 1 does not detect a finger as the object OB. In FIG. 5, the process in this case is indicated as "no touch." In step S600, the previous state of the light source 500 is maintained. That is, if the light source 500 was on when the process of step S500 was executed, the light source 500 continues to be on. If the light source 500 was not on when the process of step S500 was executed, the light source 500 remains off. Thereafter, the process of FIG. 5 ends.

[0044] The process of step S700 is executed when the proximity switch 1 detects a finger as the object OB. In FIG. 5, the process in this case is indicated as "touched." In step S700, the state of the light source 500 is changed. That is, if the light source 500 is on when the process of step S500 is executed, the light source 500 is turned off. If the light source 500 is not on when the process of step S500 is executed, the light source 500 is turned on. Thereafter, the process of FIG. 5 ends.

[0045] In this embodiment, the control unit 900 performs the process of step S600 or step S700 based on the comparison of the capacitance C10 of the first electrode unit 100 with the threshold value Cth0 and the comparison of the capacitance C20 of the second electrode unit 200 with the threshold value Cth0 in step S500. If the process of steps S500 and S700 satisfies the detection condition that the amount of change in the capacitance of the first electrode unit 100 from the minimum value Cmin exceeds the threshold value ΔCth1 and the amount of change in the capacitance of the second electrode unit 200 from the minimum value Cmin exceeds the threshold value ΔCth2, the lighting state of the light source 500 changes (see the middle left and middle right parts of FIG. 4).

[0046] By performing the above-mentioned processing, the proximity switch 1 of this embodiment changes the lighting state of the light source 500 when the object OB approaches the detection area AD1 (see the lower part of FIG. 4).

[0047] In this embodiment, the first electrode section 100 and the second electrode section 200 are not disposed within the detection area AD1 (see the upper part of FIG. 1 and the lower part of FIG. 4). Therefore, the first electrode section 100 and the second electrode section 200 do not spoil the aesthetic appearance of the detection area AD1 through which the light EL passes. Also, in this embodiment, it is not necessary to dispose a translucent member in the detection area AD1 to hide the first electrode section 100 and the second electrode section 200. Therefore, the emission direction of the light emitted from the light source 500 can be set to any direction to configure the proximity switch 1 (see EL and ELc in FIG. 2).

[0048] B. Second embodiment: FIG. 6 is an explanatory diagram showing the configuration of a proximity switch 1B according to a second embodiment of the present disclosure. Note that FIG. 6 does not accurately represent the shape and dimensions of each component of the proximity switch 1B. The proximity switch 1B according to the second embodiment includes a third electrode portion 300. Other aspects of the configuration of the proximity switch 1B according to the second embodiment are the same as those of the proximity switch 1 according to the first embodiment. The components of the proximity switch 1B according to the second embodiment that have the same configuration and function as the components of the proximity switch 1 according to the first embodiment are assigned the same reference numerals as those of the components of the proximity switch 1 according to the first embodiment.

[0049] The third electrode unit 300 changes its capacitance as the object OB approaches (see the lower center part of FIG. 6). Specifically, the third electrode unit 300 is a wiring having a similar configuration to the conductors L10, L20 except for its length and arrangement. However, the third electrode unit 300 also functions independently as a capacitance-type and projection-type proximity switch. The third electrode unit 300 is connected to the control unit 900.

[0050] The third electrode unit 300 is disposed between the detection area AD1 and the control unit 900. The third electrode unit 300 is disposed at a position between the detection area AD1 and the control unit 900 that is closer to the control unit 900. In other words, the shortest distance between the outer edge of the third electrode unit 300 and the outer edge of the control unit 900 is smaller than the shortest distance between the outer edge of the third electrode unit 300 and the outer edge of the detection area AD1.

[0051] The third electrode unit 300 is disposed between the conductor wire L10 and the conductor wire L20 on the side where the detection area AD1 exists relative to the control unit 900 (see the lower center part of FIG. 6). The third electrode unit 300, together with the conductor wire L10 and the conductor wire L20, is connected to the control unit 900 on the side where the detection area AD1 exists relative to the control unit 900.

[0052] 7 is a diagram showing the electrical connection relationship between the first electrode section 100, the second electrode section 200, the third electrode section 300, and the control section 900. The third electrode section 300 has a resistor R30. The resistors R10, R20, and R30 reduce noise contained in the signal voltages from the first electrode section 100, the second electrode section 200, and the third electrode section 300.

[0053] The light source 500 is controlled by the control unit 900 based on signals from the first electrode unit 100, the second electrode unit 200, and the third electrode unit 300, and is turned on and off.

[0054] Fig. 8 is a diagram in which a graph showing a change in capacitance C30 of the third electrode unit 300 according to the position Pob2 of the object OB is added to the graph of Fig. 4. To facilitate understanding of the technology, the lower part of Fig. 8 shows the relationship between the first electrode unit 100 and the second electrode unit 200, the conductor wires L10 and L20, and the third electrode unit 300 in the direction DL in the proximity switch 1B.

[0055] In the upper part of FIG. 8, the capacitance of the third electrode unit 300 is shown by a graph C30. The graph C30 represents a change in the capacitance of the third electrode unit 300 when a finger as an object OB is moved in the direction DL on the conductor L10, the third electrode unit 300, and the conductor L20 near the control unit 900 (see the arrow Ao2 in FIG. 6). The capacitance C30 of the third electrode unit 300 becomes a maximum value C3max when the finger is closest to the center of the third electrode unit 300 (see the upper left part of FIG. 8). In this embodiment, the position of the center of the third electrode unit 300 in the direction DL coincides with the center position P0 of the detection area AD1. When the finger as the object OB is separated from the third electrode unit 300 by a predetermined distance or more, the capacitance C30 of the third electrode unit 300 becomes a substantially constant value C3min.

[0056] In this embodiment, the maximum value C3max of the capacitance C30 is smaller than Cmax, i.e., C1max and C2max. When the finger as the object OB is separated from the third electrode unit 300 by a predetermined distance or more, the constant value C3min of the capacitance C30 of the third electrode unit 300 is smaller than Cmin, i.e., C1min and C2min. C3min can be considered as the capacitance of the third electrode unit 300 when the object OB is at an infinite distance relative to the proximity switch 1. In this embodiment, the third electrode unit 300 is configured so that the graph C30 of the change in capacitance is symmetrical with respect to the center position P0 of the detection area AD1 in the direction DL.

[0057] Fig. 9 is a flow chart showing the process in which the proximity switch 1B of the second embodiment detects the approach of an object OB. The process of Fig. 9 is executed by the control unit 900 as a processor (see the lower part of Fig. 6). In the process of Fig. 9, steps S300 and S400 are executed, which are not executed in the process of Fig. 5 of the first embodiment. More specifically, steps S300 and S400 are executed after step S200 and before step S500. Other points of the process of Fig. 9 are the same as those of Fig. 5.

[0058] In step S300, the capacitance C30 of the third electrode unit 300 is measured (see the upper part of FIG. 8). As can be seen from the upper part of FIG. 8, the capacitance C30 of the third electrode unit 300 is correlated with the position Pob2 of the object OB.

[0059] In step S400, it is determined whether or not the capacitance C30 of the third electrode unit 300 is equal to or greater than a threshold value Cth3. In this embodiment, the threshold value Cth3 is equal to the threshold value Cth0.

[0060] When the capacitance C30 of the third electrode unit 300 is equal to or greater than the threshold value Cth0, it can be inferred that a finger as the object OB is present between positions P31 and P32 in FIG. 8 (see the middle part of FIG. 8).

[0061] However, as described above, the graph C30 in Fig. 6 shows the change in capacitance of the third electrode unit 300 when a finger as the object OB is moved in the direction DL on the conductor L10, the third electrode unit 300, and the conductor L20 near the control unit 900 (see arrow Ao2 in Fig. 6). When the finger as the object OB is positioned closer to the center of the first electrode unit 100 and the second electrode unit 200, the capacitance of the third electrode unit 300 becomes a smaller value than that of the graph C30 in Fig. 8 (arrow Ao1 in Fig. 6).

[0062] Therefore, in step S400, when the capacitance of the third electrode unit 300 is equal to or greater than the threshold value Cth0, it can be inferred that a finger as the object OB is present not in the detection area AD1 of the proximity switch 1, but within the area AF above the conductor L10, the third electrode unit 300, and the conductor L20 near the control unit 900 (see the center of Figure 6).

[0063] In step S400, if the capacitance C30 of the third electrode unit 300 is equal to or greater than the threshold Cth0, the process proceeds to step S600. The process of step S600 is executed when the proximity switch 1 does not detect a finger as the object OB. If the capacitance C30 of the third electrode unit 300 is less than the threshold Cth0, the process proceeds to step S500. The subsequent process is the same as that of FIG.

[0064] In this embodiment, the control unit 900 performs the process of step S600 or step S500 and subsequent steps based on the comparison of the capacitance C30 of the third electrode unit 300 with the threshold value Cth0 in step S400. When the detection conditions are satisfied as a result of the processes in steps S300, S500, and S700, that is, the amount of change in the capacitance of the third electrode unit 300 from the minimum value C3min is less than the threshold value ΔCth3, the amount of change in the capacitance of the first electrode unit 100 from the minimum value Cmin exceeds the threshold value ΔCth1, and the amount of change in the capacitance of the second electrode unit 200 from the minimum value Cmin exceeds the threshold value ΔCth2, the lighting state of the light source 500 changes (see the middle left and middle right parts of FIG. 8).

[0065] That is, in the second embodiment, the detection conditions for executing step S700 include the amount of change in capacitance of the third electrode section 300 not exceeding the threshold value.

[0066] By performing such processing, it is possible to prevent the control unit 900 from changing the lighting state of the light source 500 when the object OB approaches the area AF outside the detection area AD1. The area AF is an area in which the conductors L10, L20 are close to each other, centered on the area between the conductor L10 connecting the first electrode unit 100 and the control unit 900 and the conductor L20 connecting the second electrode unit 200 and the control unit 900 (see the lower center part of FIG. 6).

[0067] In this embodiment, the third electrode unit 300 is disposed between the conductors L10 and L20 on the side where the detection area AD1 is located with respect to the control unit 900 (see the lower center part of FIG. 6). Therefore, when an object OB approaches the area AF, it is possible to more accurately prevent the control unit 900 from changing the lighting state of the light source 500 or outputting a detection signal to the outside of the proximity switch 1.

[0068] C. Third embodiment: In the proximity switch 1 of the first embodiment, the first electrode unit 100 and the second electrode unit 200 are configured so that the graphs C10, C20 of the change in capacitance are symmetrical with respect to the center position P0 of the detection area AD1 in the direction DL (see FIG. 4). In the determination of S500 in FIG. 5 of the first embodiment, the threshold value for the capacitance C10 of the first electrode unit 100 and the threshold value for the capacitance C20 of the second electrode unit 200 are both the same threshold value Cth0 (see the middle left part of FIG. 4). In contrast to this, in the proximity switch 1C of the third embodiment, the graphs C10, C22 of the change in capacitance of the first electrode unit 100 and the second electrode unit 200 have different shapes.

[0069] FIG. 10 shows a graph illustrating the change in capacitance C10 of the first electrode section 100 and the change in capacitance C23 of the second electrode section 200 according to the position Pob of the object OB in the third embodiment.

[0070] In the third embodiment, the threshold value Cth1 of the capacitance C10 of the first electrode unit 100 and the threshold value Cth2 of the capacitance C20 of the second electrode unit 200 in the judgment of S500 in Fig. 5 are set to different values ​​according to the graphs C10, C22 of the changes in the capacitance of the first electrode unit 100 and the second electrode unit 200 (see the middle left part of Fig. 10). Therefore, even when focusing on the amount of change in capacitance, the first threshold value ΔCth1 and the second threshold value ΔCth2 are different values. The proximity switch 1C of the third embodiment is otherwise the same as the proximity switch 1 of the first embodiment.

[0071] When the capacitance of the first electrode unit 100 is equal to or greater than the threshold Cth1 and the capacitance of the second electrode unit 200 is equal to or greater than the threshold Cth2, it can be inferred that a finger, as the object OB, is present within the section Rad2 between positions P21 and P12 in Fig. 10 (see the upper center of Fig. 10). The section Rad2 between positions P21 and P12 is a range in which the detection area AD1 exists in the direction DL (see the lower center of Fig. 10).

[0072] In the proximity switch 1C of the third embodiment, the lighting state of the light source 500 can also be changed when an object OB approaches the detection area AD1.

[0073] In the proximity switch 1C of the third embodiment, by appropriately designing the first electrode section 100 and the second electrode section 200 and their capacitance thresholds, the change in sensitivity of the proximity sensor 1C between the first electrode section 100 and the second electrode section 200 can be set to any shape, not just symmetrical (see AD1 in FIG. 2). In other words, a position at which the approach of an object OB can be detected with high sensitivity can be set to any position between the first electrode section 100 and the second electrode section 200.

[0074] In the proximity switch 1C of the third embodiment, the first electrode unit 100 and the second electrode unit 200 are also not arranged within the detection area AD1 (see the lower part of FIG. 10). Therefore, the first electrode unit 100 and the second electrode unit 200 do not spoil the aesthetic appearance of the detection area AD1 through which the light EL passes. In addition, since there is no need to arrange a translucent member in the detection area AD1 to hide the first electrode unit 100 and the second electrode unit 200, the emission direction of the light emitted from the light source 500 can be set to any direction to configure the proximity switch 1C.

[0075] D. Other embodiments: D1. Alternative embodiment 1: (1) In the first embodiment, the first electrode unit 100 and the second electrode unit 200 are self-capacitance type proximity switches (see the upper part of FIG. 1). However, the first electrode unit and the second electrode unit may be mutual capacitance type proximity switches. In this aspect, the approach of an object and its position are detected based on the coordinates of a pair of electrodes to which the object approaches, among the capacitances between multiple vertically arranged electrodes and multiple horizontally arranged electrodes provided in the electrode unit. The capacitance threshold of the first electrode unit and the capacitance threshold of the second electrode unit in this aspect can be set according to the characteristics of such electrode units (see S500 in FIG. 5).

[0076] (2) In the second embodiment, the first electrode section 100, the second electrode section 200, and the third electrode section 300 are connected to the control section 900 (see FIGS. 6 and 7). However, the first electrode section, the second electrode section, and the third electrode section may be connected to one or more components other than the control section, and the one or more other components may be connected to the control section.

[0077] (3) In the first embodiment described above, the entire detection area AD1 is illuminated by light ELc from the light source 500 (see FIG. 2). However, the proximity switch may be configured so that only a portion of the detection area is illuminated by light from the light source.

[0078] (4) In the first embodiment, the unevenness 622 is provided on the back surface of the light-transmitting plate 620 (see the middle part of FIG. 2). However, the unevenness 622 may be provided on the front surface of the light-transmitting plate 620, or on both the front and back surfaces. The unevenness 622 may also be provided inside the light-transmitting plate 620 as an interface where light-transmitting members face each other. In other words, the unevenness of the light-transmitting plate only needs to be configured so that light received by the light-transmitting plate from a light source is emitted in a direction within a predetermined range.

[0079] (5) In the first embodiment, when viewed from a direction perpendicular to the plate-shaped first electrode unit 100 and second electrode unit 200, the area occupied by the light-transmitting plate 620 coincides with the detection area AD1 (see the upper center part of FIG. 1). However, the area occupied by the light-transmitting plate 620 may be an area that includes the detection area AD1 and is larger than the detection area AD1. Also, the area occupied by the light-transmitting plate 620 may be an area that is included in the detection area AD1 and is smaller than the detection area AD1. The light-transmitting plate may be disposed between a part or all of the detection area and the light source in the direction in which light is emitted from the light source.

[0080] (6) In the first embodiment, the light-transmitting plate 620 is made of a transparent material (see the upper center part of FIG. 1 and the center part of FIG. 2). However, the light-transmitting plate may be colored to an extent that it can transmit light EL from the light source 500. In such an embodiment, the color of the light-transmitting plate may be a chromatic color or an achromatic color.

[0081] (7) In the first embodiment, a pair of the first electrode unit 100 and the second electrode unit 200 are arranged on either side of the detection area AD1 (see the upper part of FIG. 1). However, three or more electrode units may be arranged around the detection area so as to surround the detection area. Even in such an embodiment, the capacitance threshold value may be appropriately set according to the characteristics of each electrode unit. However, when viewed from a direction perpendicular to the electrode units, it is preferable that the area in which each electrode unit is arranged does not overlap with the detection area through which light from the light source passes.

[0082] (8) In the first embodiment described above, if the capacitance of the first electrode unit 100 and the capacitance of the second electrode unit 200 are both equal to or greater than the threshold value Cth0 in step S500 in Fig. 5, the process proceeds to step S700. However, if at least one of the capacitance of the first electrode unit 100 and the capacitance of the second electrode unit 200 is equal to the threshold value in step S500 in Fig. 5, the process may proceed to step S600.

[0083] In the second embodiment, if the capacitance C30 of the third electrode unit 300 is less than the threshold in step S400 of Fig. 9, the process proceeds to step S500. However, if the capacitance of the third electrode unit 300 is equal to the threshold in step S400 of Fig. 9, the process may proceed to step S700.

[0084] (9) In the above first embodiment, the threshold Cth0 is a value that the capacitance C20 of the second electrode unit 200 takes when the object OB is at position P21 directly above the corner C211 of the light-transmitting plate 620 (see the center of FIG. 4). At the same time, the threshold Cth0 is a value that the capacitance C10 of the first electrode unit 100 takes when the object OB, that is, a finger, is at position P12 directly above the corner C111 of the light-transmitting plate 620.

[0085] However, the capacitance threshold may be another value. For example, the capacitance threshold of the first electrode unit and the second electrode unit may be a value obtained by multiplying the value of the capacitance of the electrode unit when an object is located directly above the corner of the light-transmitting plate by a predetermined coefficient less than 1. The capacitance threshold can be set to an appropriate value between the maximum and minimum values ​​that the capacitance of the electrode unit can take, depending on the specifications of the proximity switch.

[0086] (10) In the first embodiment, the threshold Cth0 is applied to both the capacitance of the first electrode unit 100 and the capacitance of the second electrode unit 200 (see the middle part of FIG. 4). In the second embodiment, the threshold Cth0 is also applied to the capacitance of the third electrode unit 300 (see the middle part of FIG. 4). However, the thresholds applied to the capacitance of each electrode unit can be set independently (see the middle part of FIG. 10).

[0087] (11) In the proximity switch 1 of the first embodiment described above, in step S500 in Fig. 5, it is determined whether the capacitance C10 of the first electrode unit 100 and the capacitance C20 of the second electrode unit 200 are both equal to or greater than the threshold value Cth0. When focusing on the amount of change in capacitance, it can be understood that the condition for detecting an object in the proximity switch 1 of the first embodiment is that the amount of change in capacitance of the first electrode unit 100 from the minimum value Cmin exceeds the threshold value ΔCth1 and that the amount of change in capacitance of the second electrode unit 200 from the minimum value Cmin exceeds the threshold value ΔCth2 (see the middle left and middle right parts of Fig. 4).

[0088] However, the detection conditions for an object in the proximity switch may include other conditions, such as the condition related to the capacitance of the third electrode portion 300 described in the second embodiment. For example, the detection conditions may include that the temperature of the object detected by a non-contact type temperature sensor provided separately from the proximity switch 1 is equal to or higher than a predetermined threshold value.

[0089] (12) The control unit 900 of the proximity switch 1 in the first embodiment detects the approach of an object OB to the proximity switch 1 and changes the lighting state of the proximity switch 1 (see S700 in FIG. 5). However, instead of or in addition to changing the lighting state, the proximity switch 1 may perform a process of outputting a detection signal to the outside of the proximity switch. In such an embodiment, the proximity switch detects the approach of an object to the proximity switch and performs a process of outputting a detection signal to the outside of the proximity switch.

[0090] (13) In the technology disclosed herein, it is not essential that the process of comparing the capacitance of the electrode unit with a threshold value or the process of comparing the change in capacitance of the electrode unit with a threshold value is executed in the proximity switch. That is, when it is possible to observe by some method that "a detection condition is satisfied, including that the change in capacitance of the first electrode unit exceeds a first threshold value and that the change in capacitance of the second electrode unit exceeds a second threshold value," at least one of the process of changing the lighting state of the light source and the process of outputting a detection signal to the outside of the proximity switch is executed. Furthermore, when it is possible to observe by some method that "the change in capacitance of the third electrode unit is less than a third threshold value," at least one of the process of changing the lighting state of the light source and the process of outputting a detection signal to the outside of the proximity switch is executed.

[0091] D2. Alternative embodiment 2: The proximity switch 1B of the second embodiment includes a third electrode unit 300 (see the lower center part of FIG. 6). The detection conditions include that the amount of change in capacitance of the third electrode unit 300 from the minimum value C3min is less than a threshold value ΔCth3 (see the middle right part of FIG. 8). However, as shown in the first embodiment, the proximity switch does not need to include a third electrode unit.

[0092] D3. Alternative embodiment 3: In the second embodiment, the third electrode unit 300 is disposed between the conductors L10 and L20 on the side where the detection area AD1 is located with respect to the control unit 900 (see the lower center of FIG. 6). However, the third electrode unit may be disposed on the opposite side of the control unit from the side where the detection area is located. In general, an IC has a small dimension such that when an object approaches the multiple wirings connected to the IC, the coupling capacitance between the wirings changes. For this reason, the technology of the present disclosure is also effective in an embodiment where the third electrode unit is disposed on the opposite side of the control unit from the side where the detection area is located. However, it is preferable that the third electrode unit 300 is disposed at a position closer to the control unit 900 than the detection area AD1 and the control unit 900.

[0093] D4. Alternative embodiment 4: In the second embodiment, the cover 600 includes a light-transmitting plate 620 (see the upper center of FIG. 1 and the center of FIG. 2). However, the cover of the proximity switch may be configured not to include a light-transmitting plate. For example, the cover of the proximity switch may be configured to include a through hole that allows light from a light source to pass through.

[0094] D5. Alternative embodiment 5: In the first embodiment, the light-transmitting plate 620 has projections and recesses 622 (see the center of FIG. 2). The light-transmitting plate 620 refracts and reflects the light EL received from the light source 500 by the projections and recesses 622, and emits the light in a direction within a predetermined range. However, for example, when there is no need to control the irradiation direction of the light emitted by the light source, the light-transmitting plate may have no projections or recesses.

[0095] D6. Alternative embodiment 6: In the third embodiment, the first threshold value ΔCth1 and the second threshold value ΔCth1 are different values. However, as in the first embodiment, when the first electrode unit 100 and the second electrode unit 200 have the same characteristics, the first threshold value and the second threshold value can be the same value.

[0096] The present disclosure is not limited to the above-mentioned embodiment, and can be realized in various configurations without departing from the spirit of the present disclosure. For example, the technical features of the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention can be appropriately replaced or combined to solve some or all of the above-mentioned problems or to achieve some or all of the above-mentioned effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted. [Explanation of symbols]

[0097] 1...proximity switch, 1B...proximity switch, 1C...proximity switch, 100...first electrode portion, 200...second electrode portion, 300...third electrode portion, 500...light source, 600...cover, 610...shielding portion, 620...light-transmitting plate, 622...irregularities, 900...control portion, AD0...area in which the proximity switch can detect an object, AD1...detection area, AF...area in which the proximity switch may erroneously detect an object, Ao0...arrow indicating the movement of the object when creating the graph of FIG. 4, Ao1...other movement of the object Ao1: Arrow indicating the movement of the object when creating the graph in Figure 8, Ao2: Arrow indicating the movement of the object when creating the graph in Figure 8, C10: Capacitance of the first electrode part, C111: Corner of the transparent plate, C112: Corner of the transparent plate, C1max: Maximum value of the capacitance of the first electrode part, C1min: Minimum value of the capacitance of the first electrode part, C20: Capacitance of the second electrode part, C211: Corner of the transparent plate, C212: Corner of the transparent plate, C23: Capacitance of the second electrode part, C2max: Maximum value of the capacitance of the second electrode part, C2min: Capacitance of the second electrode part Minimum value of capacitance, C30...capacitance of the third electrode part, C3max...maximum value of capacitance of the third electrode part, C3min...minimum value of capacitance of the third electrode part, Cmax...maximum value of capacitance, Cmin...minimum value of capacitance, Cth0...threshold, Cth1...threshold, Cth2...threshold, DL...direction in which the first electrode part and the second electrode part are arranged, DP...direction perpendicular to the direction in which the first electrode part and the second electrode part are arranged, EL...light, ELc...light, GND...ground terminal, L10...conductor, L20...conductor, OB... Object, P0...center position of detection area, P11...position of object, P12...position of object, P21...position of object, P22...position of object, P31...position of object, P32...position of object, Pob...position of object, Pob2...position of object, R10...resistance, R20...resistance, R30...resistance, Rad1...section corresponding to range of detection area, Rad2...section corresponding to range of detection area, VDD...power supply terminal, ΔCth1...threshold for amount of change, ΔCth2...threshold for amount of change

Claims

1. A proximity switch for detecting the approach of an object, A first electrode unit that changes a capacitance in response to an approach of an object; A second electrode unit that changes the capacitance as the object approaches; A light source capable of emitting light; A control unit, The first electrode portion and the second electrode portion are arranged on either side of a detection area in which the proximity switch should detect the approach of an object, The light source is arranged to emit light through the detection area to an exterior of the proximity switch, The control unit performs at least one of a process of changing the lighting state of the light source and a process of outputting a detection signal outside the proximity switch when a detection condition is satisfied, the process including that the amount of change in capacitance of the first electrode portion exceeds a first threshold value and that the amount of change in capacitance of the second electrode portion exceeds a second threshold value.

2. 2. The proximity switch of claim 1, A third electrode portion that changes the capacitance as the object approaches, the first electrode unit, the second electrode unit, and the third electrode unit are connected to the control unit, The third electrode portion is disposed at a position between the detection area and the control portion closer to the control portion, A proximity switch, wherein the detection condition includes a change in capacitance of the third electrode portion being less than a third threshold value.

3. 3. The proximity switch of claim 2, A proximity switch, wherein the third electrode portion is arranged on the side of the control portion where the detection area is located, between a conductor connecting the first electrode portion and the control portion and a conductor connecting the second electrode portion and the control portion.

4. A proximity switch according to any one of claims 1 to 3, A proximity switch comprising a light-transmitting plate disposed between at least a portion of the detection area and the light source, the light being capable of transmitting light from the light source.

5. 5. The proximity switch of claim 4, The light-transmitting plate has projections and recesses, and the projections and recesses direct the light received from the light source in a direction within a predetermined range.

6. A proximity switch according to any one of claims 1 to 3, The first threshold and the second threshold are different values.

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