JPH0217895B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a touch switch.

FIG. 1 shows an oscillation type touch switch circuit in which the main circuit is switched by a touch switch. That is, this circuit consists of a DC power supply circuit A that converts AC power supply E into DC, and a main circuit B.
and a switch circuit C that switches the main circuit B.
It is composed of an oscillation circuit D that controls a switch circuit C, and its operation is as follows. That is,
The oscillation circuit D is a Colpitts oscillation circuit, and its transistor Tr ₃ is connected to a resonant circuit consisting of a pair of voltage dividing capacitors C ₃ and C ₄ connected in series and an inductance L connected in parallel. A current with a frequency f ₀ (approximately 250 KHz) determined by voltage dividing capacitors C ₃ and C ₄ flows,
A voltage V ₀ with a frequency f ₀ is generated across the inductance L. Also, the voltage V ₀ /2 (C ₃ = C ₄ ) obtained by dividing this voltage V ₀ by capacitors C ₃ and C ⁴ is the positive feedback resistor.
Positive feedback is provided to the emitter of transistor Tr ₃ via VR, resulting in a state where oscillation at frequency f ₀ continues. Note that the positive feedback resistor VR changes the feedback rate, that is, the strength of oscillation (voltage V ₀ ). When a human body touches the touch plate T of the oscillation circuit D in such an oscillation state, the human body has a capacitance and resistance between it and the earth, so the oscillation current flows from the capacitor C ₅ to the resistor R ₁ to the human body to the earth to the power source. (When the ground of the power supply E is on the side, the oscillation current returns directly from the ground of the power supply E to the oscillation circuit D. When the ground of the power supply E is on the side, the oscillation current flows to the ground of the power supply E.)
from the ground to the oscillation circuit through elements such as capacitor _C1 ). The capacitance and resistance that the human body has between itself and the earth are equivalently a series circuit of them.
This series circuit is connected in parallel with the capacitor C ₅ and the resistor R ₁ to both ends of the inductance L, and functions as a composite capacitor C _T and a composite resistor R _T as shown in Fig. 2, and the oscillation state is reached before this series circuit enters. The oscillation is shifted from the state of 1 to become weaker, and the oscillation stops. In other words, by touching the touch plate T, the operation of the oscillation circuit D can be controlled.

In the switch circuit C, when the oscillation circuit D is oscillating, the oscillation voltage biases the base of the transistor Tr ₂ , and the collector-emitter voltage of the transistor Tr ₂ becomes a ripple voltage of about 100 mV due to the capacitor C ₂ . is very small, so the transistor _Tr1 is turned off and the main circuit B is turned off. On the other hand, when the oscillation circuit D has stopped oscillating,
Transistor Tr ₂ is turned off and transistor
The collector-emitter voltage of Tr ₂ is approximately 15V.
This voltage turns on the transistor _Tr1 and turns on the main circuit B.

By the way, using the above-mentioned touch switch, the connection part G with a built-in magnet as shown in Fig.
is attached to the touch plate T and electrically connected, the lead wire U is connected to the connection part G, and the touch plate T' is connected to the end of the lead wire U, and the oscillation is also caused by touching the touch plate T' with the human body. Stopping the oscillation of circuit D is convenient because main circuit B can be easily operated remotely.

However, if the constant of the oscillation circuit D of the touch switch circuit is adjusted so that it operates normally by touching the touch plate T in all the places where it can normally be used, the touch plate with lead wires
When T' is connected, there will be a place where a malfunction will occur where the oscillation circuit D will stop oscillating and the main circuit B will turn on without touching the touch plate T'. For example, in both concrete floors and Japanese-style rooms,
If the touch switch is set to a sensitivity that allows direct touch operation to the touch plate T, the main circuit B will be turned on simply by connecting the touch plate T' with a lead wire at a place on the concrete floor. This is the capacitance and resistance of the human body that enters between the touch board T and the earth in a Japanese-style room, and the touch board that enters between the touch board T' and the earth when the touch board T' with lead wire is connected in the case of a concrete floor. This is thought to be because the capacitance and resistance of the lead wire U of T' have very similar values.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a touch switch that can prevent malfunctions even when a touch plate with lead wires is connected.

A first embodiment of the invention is shown in FIGS. 4 and 5. That is, in this touch switch, a touch capacitor _C5 is connected to one end of an inductance L _of an oscillation circuit D.
A first resistor _R1 and a first touch plate T constituting a first touch circuit are successively connected in series. At this time, the first resistor R ₁ is connected to the first touch plate T.
It has a resistance value that causes the oscillation circuit D to stop when touched. Further, a second resistor R ₂ , a lead wire U, and a second touch plate T' constituting a second touch circuit are connected in series to the touch capacitor C ₅ . Q is the connection part of the lead wire U.
FIG. 5 shows a perspective view of a state in which the lead wire U and the second touch plate T' are connected to the connecting portion Q. At this time, the second resistor _R2 has a resistance value smaller than that of the resistor _R1 , and is set to a resistance value that will not stop the oscillation of the oscillation circuit D when the lead wire U with the second touch plate T' is connected. There is. The rest is the same as in FIG. 1, so details will be omitted.

Next, the settings of resistors R ₁ and R ₂ will be explained.
That is, the effect of the resistor R _T in the oscillation circuit of FIG. 2 is that it is an oscillation control element that consumes the vibration energy of the circuit and dampens the vibration, and the vibration energy consumed by the resistor R _T is reduced by the capacitance C _T . The larger the oscillating current flowing through the series circuit of the resistor R _T is, the larger the value of the resistor R _T is, and the larger the oscillating current flowing through the series circuit is as the impedance of the capacitor C _T and resistor R _T is smaller. C _T , resistance
It has the function of changing the amount of vibration energy consumed by the resistor R _T depending on the combination of R _T.
In reality, when the capacitance C _T is constant, when the impedance of the capacitor C _T and the impedance of the resistor R _T become equal, the vibration energy consumed by the resistor R _T increases, and the vibration energy consumed by the resistor R _T increases. The larger the value, the weaker the oscillation becomes, and when the value exceeds a certain value, the oscillation stops.

Figure 6 shows a relationship diagram of oscillation operation with respect to resistance R ₁ .
When the first touch plate T is directly touched for the magnitude of the resistance R ₁ at the location, and when the second touch plate T' is connected via the lead wire U (the second
This is a plot of the minimum value of the positive feedback resistor VR for operating the main circuit B when the lead wire U with the touch plate T' is connected. In the figure, the curve _W
This is the characteristic when the touch plate T is directly touched, and the curve _W
The curve W _Y is the characteristic when the first touch plate T is touched directly at the location Y, and the curve W _Y ′ is the characteristic when the first touch plate T is connected at the location Y.
In each case, the upper side of each curve is the operating range of main circuit B, that is, the oscillation stop region, and the lower side is the non-operating range, that is, the oscillation range of main circuit B.

This figure 6 shows a negative characteristic when the resistance R ₁ is smaller than a certain resistance value, and assuming that the capacitance and resistance between the touch capacitor C ₅ and the human body and the earth are constant, and the resistance R ₁ is increased, the resistance Since the vibration energy consumed by R ₁ increases, the minimum value of the positive feedback resistor VR becomes small and oscillation stops easily, and the minimum value is the smallest when the resistor R ₁ has a certain value.

Also, from the characteristics shown in Fig. 6, main circuit B operates by direct touch operation at both location _X and location _Y , so that _{curve W} For curve W _Y
This is the area above. Also, the reason _why the main circuit B does not operate even if the second touch plate T' is connected via the lead wire U is because the curve W _X ' is below _the curve W _Y ′, so the curve
This is the area below W _X ′.

Therefore, in Figure 6, when the resistance _R1 is smaller than a certain resistance value, it has a negative characteristic, so the positive feedback resistance is
A resistance that satisfies the above conditions at a certain value of VR
It can be seen that R ₁ and R ₂ exist. For example, set the resistance value of the positive feedback resistor VR to VR, and set the resistor R ₁
If the value of is determined to be in the area above the curve W _Y , for example at point _A , and the resistance R ₂ is determined to be in the area below the curve W When this happens, the main circuit B operates, but by simply connecting the second touch plate T', it is possible to obtain a state in which the main circuit B does not operate.

On the other hand, when the second touch plate T' is touched, the oscillation circuit D can be stopped and the main circuit B can be operated due to the resistance and capacitance that the human body has between itself and the ground.

With this structure, according to this embodiment, malfunction can be prevented even when the second touch plate T' is connected via the lead wire U, and direct operation and remote operation are possible.

A second embodiment of the invention is shown in FIG. That is, this touch switch is connected to the first touch plate.
The contact surface of the first touch circuit is provided with an uneven part that increases the contact resistance when the human body comes into contact with
The resistor consists of a resistor and the contact resistance, the second resistor of the second touch circuit is the resistor, and the lead wire U is connected to the first touch plate T''.Others are as follows. This is similar to the first embodiment.

As described above, the touch switch of this invention is
a resonant circuit in which an inductance is connected in parallel to a pair of capacitors connected in series; a transistor having one end connected to the resonant circuit; and a connection point between the pair of capacitors and the other end of the transistor. a touch capacitor connected to one end of the inductance; a first touch plate connected to the touch capacitor; a first touch circuit having a first resistor inserted between the first touch plate and the touch capacitor and having a resistance value that stops the oscillation circuit by touching the first touch plate; , a second touch plate connected to the touch capacitor via a lead wire, the second touch plate being inserted between the lead wire and the touch capacitor, the resistor being smaller than the first resistance, and having a second touch plate connected to the touch capacitor via a lead wire; When the lead wire connected to the second touch plate is connected, the oscillation of the oscillation circuit is not stopped, and the second touch plate is connected.
a second touch circuit having a second resistor having a resistance value that causes the oscillation of the oscillation circuit to be stopped by touching the touch plate; Since it is equipped with a switch circuit for

That is, a second resistor is provided at the lead wire connection part, which is smaller than the first resistor of the first touch circuit and has a resistance value within a range in which the oscillation circuit does not stop oscillating when the second touch plate is connected. Save,
This has the effect of preventing malfunctions caused by connecting the second touch plate.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a touch switch, Fig. 2 is its oscillation circuit diagram, and Fig. 3 is a perspective view of a state in which a second touch plate with a lead wire is connected to the first touch plate.
FIG. 4 is a partial circuit diagram of the first embodiment of this invention,
Figure 5 shows a second type with a lead wire attached to the lead wire connection part.
FIG. 6 is a diagram showing the relationship between the oscillation operation and the resistance, and FIG. 7 is a sectional view of the first touch plate of the second embodiment. L...Inductance, _C3 , _C4 ...Capacitor, _C5 ...Touch capacitor, _Tr3 ...Transistor, VR...Resistance for positive feedback, B...Main circuit, C...Switch circuit, D ...oscillation circuit, T,
T″……first touch plate, T′……second touch plate,
U...Lead wire, _R1 ...First resistor, _R2 ...Second resistor.

Claims (1)

[Claims] 1. A resonant circuit comprising a pair of capacitors connected in series and an inductance connected in parallel, a transistor having one end connected to the resonant circuit, and a connection point between the pair of capacitors. and the other end of the transistor, a touch capacitor connected to one end of the inductance, and a first touch plate connected to the touch capacitor. and a first resistor inserted between the first touch plate and the touch capacitor and having a resistance value that stops the oscillation circuit by touching the first touch plate. a first touch circuit; and a second touch plate connected to the touch capacitor via a lead wire, the touch plate being inserted between the lead wire and the touch capacitor, is small, and the oscillation of the oscillation circuit is not stopped when the lead wire connected to the second touch plate is connected;
a second touch circuit having a second resistor having a resistance value that causes the oscillation of the oscillation circuit to be stopped by touching the touch plate; A touch switch equipped with a switch circuit. 2. The first touch plate has a concavo-convex portion on the contact surface that forms a contact resistance when a human body comes into contact with it, the first resistor is composed of a resistor and the contact resistance, and the second resistor is composed of a resistor and the contact resistance. 2. The touch switch according to claim 1, wherein the touch switch is a resistor, and the lead wire is connected to the first touch plate.