JP3480276B2 - Touch switch - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a touch switch for performing on / off control of a load such as lighting by touching a touch surface with a finger.

[0002]

2. Description of the Related Art Various methods have been devised for a touch switch that controls the on / off of a load of an electric device or the like by detecting that a finger or the like approaches or touches the touch surface. Among them, the method of detecting the approach or contact of a finger or the like by the change of electrostatic capacity has high durability because there are almost no moving parts.

The touch switch which detects the change in the electrostatic capacitance as described above has a unipolar structure which detects a change in impedance due to the approach or contact of a finger or the like with the touch detection electrode, or a touch switch of the substrate. There is a three-pole structure in which a touch electrode is formed on one surface and a pair of detection electrodes is formed on the other surface.

In the touch switch having the above-mentioned structure, it is necessary to bring a finger or the like into close contact with the touch detection electrode (touch electrode) or through a coating material applied to the surface of the touch detection electrode. There is a problem that detection is not performed when the distance between the surface of the finger and the touch detection electrode becomes large, such as when the finger is attached.

In order to solve this problem, therefore, a pair of touch detection electrodes are formed on one surface of the substrate, and the surface thereof is covered with an insulating substrate to form a bipolar structure. A touch detection device has been developed that changes the capacitance.

In the touch switch described above, when the impedance between the finger and the touch detection electrode, which can be electrically approximated to a ground conductor, or the electrostatic capacitance between the touch detection electrodes is below a certain threshold value, or below the threshold value. Touch determination is performed such that a finger is touching the touch surface when the state continues for a certain time or longer.

[0007]

However, in the touch switch having the above-described configuration, when the touch determination is performed based on the threshold value, the touch detection section constituent material and the touch detection determination circuit component are changed due to the change of environment such as temperature. Since the electrical characteristics such as permittivity and impedance change, the steady value fluctuates when a finger or the like does not exist near the touch surface, and the distance between the finger and the touch surface required to change from this steady value to the threshold value. Will be different.

For this reason, in the conventional touch switch, the detection sensitivity changes as the environment changes. Specifically, there is a problem in that, when the temperature is low, the sensitivity is lowered, so that even if a person touches the touch surface, the detection cannot be performed, and when the temperature is high, the sensitivity is too high, resulting in erroneous detection.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a touch switch that enables accurate touch detection regardless of changes in the environment. .

[0010]

The invention according to claim 1 is
A predetermined change speed is calculated by calculating the change speed of the electrostatic capacitance between the touch detection electrodes and the electrostatic change detection means that detects the change in the capacitance between the touch detection electrodes that changes with the approach or contact of a finger or the like. From the time when the above change occurs, a touch determination circuit that determines touch detection when the change at a predetermined change rate or more continues for a predetermined change duration time or more.

According to a second aspect of the present invention, there is provided electrostatic capacitance change detection means for detecting a change in electrostatic capacitance between the touch detection electrodes which varies with the approach and contact of a finger or the like, and an electrostatic capacitance between the touch detection electrodes. And calculates the first capacitance value when the change of the predetermined change speed or more continues for a predetermined change duration or more from the time when the change of the predetermined change speed or more occurs. The touch detection operation is started, and after that, when the capacitance between the touch detection electrodes is equal to or less than the first capacitance value for a certain period of time, the touch determination circuit determines the touch detection. It is what

According to a third aspect of the present invention, in the touch switch according to the first or second aspect, the position of the object to be detected at the time when a change of a predetermined change speed or more occurs is set near the touch surface. It is characterized by having done.

According to a fourth aspect of the present invention, in the touch switch according to the first to third aspects, the change duration is 3
The feature is that it is set to about 0 msec.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described in detail below with reference to FIGS.

FIG. 1 is a circuit diagram of the touch switch. FIG. 2 is a side cross-sectional view of the touch detection unit that constitutes the touch switch. FIG. 3 is a pattern diagram of the touch detection electrodes. FIG. 4 is a circuit configuration diagram of the RC oscillator circuit. FIG. 5 is an external view of the touch switch, (a) is a front view, and (b) is a side view. FIG. 6 is a flow chart showing a process from power-on to process A. FIG. 7 is a flowchart showing a process from the start of the process A to the process B. FIG. 8 is a diagram showing a pulse waveform oscillated by the RC oscillator circuit and an oscillation cycle. FIG. 9 is a diagram showing the oscillation cycle of the RC oscillator circuit and the change rate of the oscillation cycle at that point in time series. FIG. 10 is a diagram showing a cycle table and a speed table for storing the oscillation cycle and the change rate of the oscillation cycle in the order of occurrence in the touch determination circuit. FIG. 11 is a state transition diagram showing a process until the touch determination circuit determines whether or not a finger or the like is touching the touch detection unit after the initial setting is completed. FIG. 12 is a diagram showing changes in the oscillation cycle of the touch detection unit with the passage of time, transitional states with the changes, and load states at that time.
FIG. 13 is a flowchart showing the process from the start to the end of the process B. FIG. 14 shows the change duration and the touch surface and the fluorescent tube when the touch switch malfunctions when the power of the inverter stand is controlled to be turned on and off while the fluorescent surface of the inverter stand is horizontally illuminated on the touch surface of the touch switch. It is a measurement of the distance to. FIG. 15 shows a grounded iron plate with a height of about 6 so as to cover the front surface of the touch surface.
This is a measurement of the number of times touch detection is confirmed within 10 times when the apparatus is stationary after approaching from a distance of cm to a certain distance at a speed of 40 mm / sec and then stopped.

As shown in FIG. 1, the touch switch includes a touch detection unit 1, a power supply circuit 3, a load control circuit 5, and an R.
It is composed of a C-shaped oscillator circuit 7 and a touch determination circuit 9.

The touch detection section 1 has a pair of touch detection electrodes 13 and is insulated from each other. Therefore, when electric power is supplied, the lines of electric force extend from one electrode toward the other electrode, and electrically function as a capacitor.

As shown in FIG. 2, the touch detection section 1 has a pair of touch detection electrodes 13 formed on one surface of an insulating substrate 11, and the touch detection electrodes 13 are covered with an insulating resin 15 and formed thereon. It is configured by arranging the insulating plate 17. A shield electrode 19 is formed on the other surface of the insulating substrate 11. The touch detection electrode 13 having a pattern as shown in FIG. 3 is formed on the insulating substrate 11.

The insulating substrate 11 is a printed wiring board made of glass epoxy resin. The touch detection electrode 13 and the shield electrode 19 are made of copper. Further, the insulating resin 15 is made of a solder resist, and the insulating plate 17 is made of an insulating resin material such as acrylic or polycarbonate.

Glass is used as the insulating substrate 11, a transparent electrode made of indium oxide or tin oxide is used as the touch detection electrode 13, a transparent polymer resin is used as the surface insulating material, and a transparent material such as acrylic is used as the insulating plate 17. A light emitting unit (not shown) may be provided on the back surface of the touch detection unit 1 using. This makes it possible to form an illuminated touch switch that enables the location of the touch switch to be recognized even in the dark by turning on the light emitting unit.

When a finger or the like approaches or contacts the touch sensing unit 1, the human body can be electrically treated as a ground conductor, so that a part of the line of electric force approaches the touch sensing unit 1. Electrode 1 for touch detection in order to extend to the finger etc.
The number of lines of electric force between 3 and 13 will decrease. That is, when a finger or the like approaches or contacts the touch detection unit 1, the capacitance between the touch detection electrodes 13 and 13 decreases.

Since the shield electrode 19 formed on the touch sensing portion 1 is held at a constant potential (GND potential in FIG. 1), a change in the electric field distribution on the back side of the touch sensing portion 1 is caused by the touch sensing electrode. There is no influence on the change in the electric field distribution between 13 and 13. Therefore, by applying electrical noise from the outside, the touch detection electrodes 13 and 13 are
The capacitance between them does not change.

The power supply circuit 3 supplies the electric power obtained from the power supply 40 to
Electric power is supplied to the load 50 such as lighting, the touch determination circuit 9, and the RC type oscillation circuit 7. The load control circuit 5 is
Based on a signal from the touch determination circuit 9, whether or not to supply power to the load 50 is controlled.
It controls ON / OFF of 0.

The RC oscillator circuit 7 has a structure as shown in FIG. 4, and is formed by connecting inverter elements G1 and G2 in series. This RC type oscillation circuit 7 uses a known inverter circuit. When the capacitance of the capacitor connected to the outside of the inverter circuit is C, the resistance value of the feedback resistor is R, and the oscillation cycle is P, P = KR
Have a relationship of C. It should be noted that K is a coefficient, which is a constant determined by the power supply voltage of the inverter circuit, the threshold voltage for logic determination, and the like. Therefore, since the resistance value R is constant, the oscillation period P is proportional to the capacitance C between the touch detection electrodes 13 and 13, and thus the touch operation unit 1 when the finger approaches the touch operation unit 1
The change in the electrostatic capacitance C can be detected by measuring the oscillation period P of the RC oscillator circuit 7.

The touch determination circuit 9 is based on the oscillation cycle P of the RC oscillator circuit 7 described above, and a finger or the like approaches the touch surface.
It is determined that the contact has been made, and the procedure will be described later.

Next, the touch detection operation of the touch determination circuit 9 will be described. As shown in FIG. 6, when the power is turned on and the AC power supply AC is applied, the RC oscillator circuit 7 starts oscillating, and the pulse signal is input to the touch determination circuit 9. At that time, as the initial operation, the touch determination circuit 9 initializes each variable, turns off the power supplied to the load 50, and waits for a predetermined time tpp which is one cycle of the input pulse. After that, for example, the trailing edge of the input pulse, which is the output signal from the RC oscillator circuit 7, is monitored, and a transition is made to a standby state for detecting that a finger or the like touches the insulating plate 17. The process after the standby state is called process A here, and the process A will be described below.

The process A will be described with reference to FIG. The time at which the above-mentioned standby state is entered is P0, the pulse waveform and the oscillation cycle oscillated by the RC oscillator circuit thereafter are shown in FIG. 8, and the oscillation cycle and the rate of change of the oscillation cycle at that time are shown in FIG. Shown in. The change in the oscillation cycle speed means the oscillation cycle P [k] measured this time to the oscillation cycle P previously measured.
The difference of [k-1] is obtained, and this is divided by the time P [k] required for changing the oscillation period.

First, the oscillation cycle P of the RC oscillator circuit 7 measured last time is defined as the previous oscillation cycle Pprev. However, when the process A is executed for the first time, the oscillation period P of the previous time is not measured, so the initial setting is not completed.

Next, the latest oscillation period Pcur which is the latest oscillation period of the oscillation period P is measured. Now, the latest oscillation cycle Pcur
Is P1, this value is stored in the storage area Pt [7] of the cycle table of the touch determination circuit 9, as shown in FIG. The cycle table has a pipeline type queue structure, and has a structure in which a predetermined number of oscillation cycles P are stored in the order of occurrence. Therefore, for example, in the case of FIG. 10, it has eight storage areas Pt [0] to Pt [7],
The oscillation cycle P generated the ninth time is overwritten in the cycle table in which the oscillation cycle P generated the first time is written.

Next, the number of times Np of measurement of the oscillation period necessary for the elapse of the predetermined change duration Tc is calculated. The elapsed time can be obtained by going up from the current time and taking the sum of the oscillation periods P in the period table. Therefore, the number of oscillation cycles P, which has been measured backwards in the past, is integrated, and the number of oscillation cycles P accumulated up to that point when the sum exceeds the change duration time Tc is the number of times of measurement Np.

Then, the current change speed Vcur, which is the change speed of the latest oscillation cycle P, is obtained from the previous oscillation cycle Pprev and the current oscillation cycle Pcur. The speed table of the cycle table has a pipeline-type queue structure like the cycle table, and is "1" when the oscillation cycle P decreases by a predetermined speed threshold | Vth | or more in the order of occurrence. Store
In other cases, "0" is stored.
It should be noted that in FIG. 10, V is not described as “0” and “1”.
It is described as 1, V2, ...

Next, in the process A, it is judged whether or not the initial setting is completed. In the initial setting, in the above-mentioned cycle table, the initial setting is completed when a measurement cycle of Np or more measurement times necessary for the change duration time Tc to pass is stored. Therefore, from the start of the process A until the change continuation time Tc elapses, it is assumed that the initial setting is not completed, and the subsequent touch determination process (hereinafter referred to as the process B) is not performed.

When the above-described change duration time Tc has elapsed and the oscillation period P equal to or greater than the change duration time Tc is stored in the cycle table, the initialization is completed, and therefore the process A is followed by the process B described later.

The process B will be described with reference to FIGS. 11 and 12. Hereinafter, a case where the oscillation cycle P of the touch detection unit 1 changes as shown in FIG. 12 due to the approach of a finger will be described.

In the process A, the change rate | Vcur | calculated from the value of the oscillation period P sampled at each fall of the pulse signal becomes a predetermined value | Vth | If the rate of decrease of the oscillation period P is equal to or higher than Vth and the rate of decrease of the oscillation period P is equal to or higher than Vth until time b, the speed table is changed over the past change duration Tc. “1” is stored in the storage area of the number of measurement times Np. When this state is reached, the process B is performed.

The procedure of process B is as shown in FIG. When the latest oscillation cycle Pcur at time b is set as the oscillation cycle threshold Pth, the timer is started at time b, and when the value of the oscillation cycle P measured over time Tw is equal to or less than Pth (time c), the touch detection unit is detected. The touch detection is confirmed as if there is a finger or the like touching 1. At this time, the touch determination circuit 9 outputs a touch detection signal to the load control circuit 5. In response to this, the load control circuit 5 supplies electric power to the load 50, for example, and the load 50 is turned on.

The state column in FIG. 12 corresponds to each state in the state transition diagram in FIG. 11, and transitions from state 5 to state 7 at time b in FIG. 12 and continues for a predetermined time Tw in state 7 When continues, the state transitions to state 8 and the touch detection is confirmed.

When the finger is separated from the touch surface and the oscillation period P becomes higher and exceeds the oscillation period threshold Pth set at time b, and a predetermined time t1 or more elapses, the state transits to the state 5 again, and the next The touch input is accepted. After the elapse of time e, when the touch detection is confirmed by the approach of the finger or the like again, the load 50 is turned off.

In FIG. 11, if V <Vth and the latest definite state is state 5, state 6 to state 7
And Pcur <Pth and the latest definite state is state 8
If there is, it transits from state 6 to state 9. Further, when the state 6 is continued for the change duration time Tc or more, the state 6 is transited to the state 5 and the state 7
Is changed from the state 7 to the state 8 when is continued for a change duration time Tc or more. Further, if the state 8 or the state 9 continues for a predetermined time Tt or more,
This is a transition to state 5.

As shown in FIG. 11, state 5 to state 7,
If the conditions for the transition from state 7 to state 8 or state 8 to state 5 are not satisfied (for example, if the oscillation period Pth is exceeded before the touch time is short and Tw time has elapsed) The states 6 and 9 are provided in order to prevent the switching operation from being performed only when the transition from the state 5 to the state 7 to the state 8 is surely performed. State 6,
State 9 is due to electrical noise from the outside world.
In order to avoid a malfunction when the state 9 continues or the state 9 continues, if the state 8 or the state 9 continues for a predetermined time Tt or more, the state transitions to the state 5 to receive the next touch input. Therefore, the touch detection operation can be continued even in a state where electrical noise or the like is applied from the outside, and thus a malfunctioning state or the like does not occur.

FIG. 14 shows that the power of the inverter stand is turned on while the fluorescent surface of the inverter stand (3SP16BN manufactured by NEC Corporation is used) is horizontally irradiated on the touch surface of the touch switch as an electrical noise source. When the off control is performed, the change duration time Tc is set to 30 msec, 40
It shows the result of measuring the distance between the touch surface and the fluorescent tube when the touch detection has confirmed the touch detection in the case of msec and 50 msec. It can be seen from FIG. 14 that the malfunction distance is reduced by the increase of the change duration time Tc, but if the application of the touch switch is a switch that is mounted on the wall and controls the lighting equipment arranged on the ceiling,
If there is no malfunction at a distance of m or more, there will be no particular problem in use.

FIG. 15 shows a grounded iron plate (50 × 100).
X 1 mm) height about 6 cm to cover the entire touch surface
This is a measurement of the number of times the touch detection is confirmed in 10 times when the user stands still after approaching a certain distance at a speed of 40 mm / sec from the distance of 10 mm. From FIG. 15, when the change duration time Tc is set to 30 msec, the detectable distance becomes longer than when the change duration time is set longer and the probability of touch detection above the touch surface becomes higher. That is, when the change duration time Tc is set to 30 msec, the touch detection distance when a finger or the like is brought close to the touch surface becomes long, and thus a softer touch operation feeling can be obtained.
Further, the probability of touch detection is high even when the distance between the surface of the finger and the touch detection electrode 13 is large as in the case of wearing gloves, and the feeling of operation is not impaired even when wearing gloves. .

Although the touch detection is determined based on the oscillation period P in the present embodiment, the oscillation period P
Alternatively, the change in the capacitance C may be detected, and the touch detection may be confirmed by the same procedure.

[0044]

As described above, according to the first aspect of the present invention, the detection determination is performed based on the rate of decrease in the capacitance between the touch detection electrodes that fluctuates due to the capacitance of the human body. As a condition for touch detection, the point at which a change more than a predetermined change speed occurs is the base point.Therefore, if the predetermined change speed is set above the capacity change speed due to environmental changes such as temperature change, it becomes abrupt. Since the malfunction does not occur even when the environment changes, it is possible to provide a touch switch that enables accurate touch detection regardless of the environment change. In addition, since the touch due to the slow approach of the detected object is not detected, it is possible to avoid the switching operation due to the approach to the touch part in an unintentional state such as when approaching the touch surface without noticing the switch. Has the effect of becoming.

Further, in the method of judging the touch detection based on the threshold value of the electrostatic capacity, there is a problem that the distance at the time of confirming the detection varies depending on the size of the approaching object. In the present invention in which the detection determination is performed based on, since it is necessary to continuously reduce the capacitance generated by the continuation of the approach operation in order to start the touch detection,
The effect that the difference in the distance when the detection is determined due to the size of the approaching object is less likely to appear in the detection determination is achieved.

According to the invention of claim 2, claim 1
In addition to the effect of the touch switch described, after the touch detection is started, the touch detection is confirmed when the capacitance is monitored for a certain period of time and is equal to or less than a preset threshold value.
It is possible to avoid the switch operation due to the involuntary approach to the touch part when the finger is in contact with the touch surface for a short time such as when the finger touches the touch surface without noticing the switch. .

According to the invention of claim 3, claim 1
Alternatively, in the touch switch according to claim 2, since the change over the change speed continues for a predetermined time regardless of the approach speed of the detected object such as a finger to the touch surface, a more accurate operation feeling is obtained. It becomes possible.

According to the invention of claim 4, claim 1
Further, in the touch switch according to the third aspect, since the change duration time is set to about 30 msec, there is an effect that good touch operability can be obtained while having electrical noise resistance.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of a touch switch.

FIG. 2 is a side cross-sectional view of a touch detection unit that constitutes a touch switch.

FIG. 3 is a pattern diagram of a touch detection electrode. FIG. 4 is a circuit configuration diagram of the RC oscillator circuit.

FIG. 4 is a circuit configuration diagram of an RC oscillator circuit.

FIG. 5 is an external view of a touch switch, (a) is a front view, and (b) is a side view.

FIG. 6 is a flowchart showing a process from power-on to process A.

FIG. 7 is a flowchart showing a process from the start of process A to the process B.

FIG. 8 is a diagram showing a pulse waveform oscillated by an RC oscillator circuit and an oscillation cycle.

FIG. 9 is a diagram showing, in a time-series manner, an oscillation cycle in which an RC-type oscillation circuit oscillates and a change rate of the oscillation cycle at that time.

10A and 10B are diagrams showing a cycle table and a storage table in which the oscillation cycle and the rate of change of the oscillation cycle are stored in the touch determination circuit in the order of occurrence.

FIG. 11 is a state transition diagram showing a process until the touch determination circuit determines whether or not a finger or the like is touching the touch detection unit after the initialization is completed.

FIG. 12 is a diagram showing a change in the oscillation cycle of the touch detection unit with the lapse of time, a transition state accompanying the change, and a load state at that time.

FIG. 13 is a flowchart showing a process from the start to the end of process B.

FIG. 14: Change duration time when the power of the inverter stand is controlled to be turned on and off while the fluorescent tube surface of the inverter stand is horizontally illuminated on the touch surface of the touch switch, and the touch surface and fluorescence when the touch switch malfunctions It is a measurement of the distance to the pipe.

FIG. 15: Touch detection is confirmed within 10 times when the grounded iron plate covers a front surface of the touch surface and is stationary after approaching a certain distance at a speed of 40 mm / sec from a distance of about 6 cm. The number of times is measured.

[Explanation of symbols]

1 Touch detector 3 power supply circuit 5 Load control circuit 7 RC type oscillation circuit (electrostatic change detection means) 9 Touch judgment circuit 13 Touch detection electrode

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A 5-160702 (JP, A) JP-A 4-140916 (JP, A) JP-A 62-9423 (JP, A) JP-A 10- 64386 (JP, A) JP-A-7-114866 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H03K 17/00 H01H 36/00

Claims (4)

(57) [Claims] 1. A capacitance change detecting means for detecting a capacitance change between the touch detection electrodes which varies with the approach and contact of a finger or the like, and a change rate of the capacitance between the touch detection electrodes is calculated. A touch determination circuit that determines touch detection when a change of a predetermined change speed or more continues for a predetermined change duration or more from a time of a change of a predetermined change speed or more. Touch switch. 2. An electrostatic change detection means for detecting a change in electrostatic capacitance between the touch detection electrodes which varies with the approach and contact of a finger or the like, and a change speed of the electrostatic capacitance between the touch detection electrodes. , When the change of the predetermined change speed or more continues from the time of the change of the predetermined change speed or more for a predetermined change duration or more, the first capacitance value is detected and the touch detection operation is started. Then, after that, when the electrostatic capacitance between the touch detection electrodes is equal to or less than the first electrostatic capacitance value for a certain period of time, the touch detection is determined by the touch determination circuit. 3. The touch switch according to claim 1, wherein the position of the object to be detected at the time when a change of a predetermined change speed or more occurs is set near the touch surface. 4. The touch switch according to claim 1, wherein the change duration is about 30 msec.