KR20170105322A - touch sensor - Google Patents

Abstract

The present invention relates to a body-contact type touch sensor, and provides a simpler touch sensing circuit structure, thereby minimizing standby current consumption and the number of parts used in a portable small device using a battery. The body-contact type touch sensor includes a sensing metal piece, an oscillating part, a rectifying part, and an output part.

Description

Touch sensor {touch sensor}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a touch sensor, and more particularly, to a touch sensor in which a part of a body,

A touch sensor which generates a switching signal by using a difference of a rectified voltage generated when the oscillating action of the oscillating part is suppressed

.

In the conventional touch-type touch sensor, there is a method of detecting a change in impedance between two electrode plates,

And to attach two electrode plates, there is a problem that the mechanical design part becomes large. Thus, in recent years,

A capacitive touch sensor that detects contact of a body using only a plate has been developed and used. Korea Registered Utility Model Gazette

Lock No. 20-0238102, Capacitive Touch Sensors According to the invention, the detection circuit, oscillator, rectifier, differential amplifier, comparator and reference voltage setting section

And adopts a method of generating a body detection signal coming from a single-pole detection board as a switching signal. According to this design

Although its structure is simple, it can be used in small handheld devices. However, it still has a large number of components and especially a large number of active elements

Therefore, there is a problem in that it is difficult to realize the consumption current in a standby state at a certain level or less.

It is therefore an object of the present invention to provide a touch sensor circuit with fewer components and less standby current consumption.

First, the circuit of the oscillation unit is minimized and the input of the sensing metal piece and the collector of the oscillation unit transistor and the rectification unit are combined into one

When the body is touched and the body contacts, the oscillation suppression function and the charge voltage discharge are simultaneously performed,

A portion of the differential amplifier, the reference voltage setting unit, and the like included in the conventional method can be omitted,

We use a number of silver parts, especially a small number of active elements to implement a touch sensor that minimizes standby current consumption.

It has its purpose.

As described above, according to the touch sensor of the present invention, it is possible to use a single-pole sensing metal piece for contacting with a body,

Detects the contact of a conductor or the like held by the hand, converts it into a logical switching signal, and outputs the logical switching signal.

Minimizing the number of parts minimizes the mounting volume and minimizes the current consumption during standby.

Thereby reducing the power consumption and providing the effect of miniaturization of the device and long-term use of the power source.

FIG. 1 is a circuit diagram according to a preferred embodiment of the present invention, showing the configuration and detailed circuit of an oscillating portion, a rectifying portion, and an output portion. 2

Shows an internal block diagram in which a parallel detection port is formed by using several touch sensor circuits of the present invention in one IC. 1

As shown, the oscillation unit 101 uses one NPN transistor Q1 as an oscillator and the collector of Q1 is connected to the oscillation inductor

The emitter of Q1 is grounded via the current limiting resistor R1, and the base of Q1 is connected to the power supply voltage Vcc via a bias

The resistor R2 and the capacitor C2 are connected to the power supply Vcc and the ground, respectively, and between the collector and the emitter of Q1,

The capacitor C1 is connected to constitute a simple oscillation circuit using one transistor. Here, the oscillator Q1 is L1, C1,

Oscillates at a predetermined frequency determined by the capacitance of the metal piece 100 and the peripheral stray impedance,

The size and waveform are determined according to the definition. The sensing metal piece 100, which is in contact with a part of the user's body or a conductor held in the hand,

Q1, and the input of the rectifying unit 102 is also directly connected thereto. The sensing metal piece 100 may have a body

When there is no contact, an oscillation signal is input from the oscillation unit 100 to the input of the rectification unit 102 and rectified by the rectification diode D1

Converted into a DC voltage, and then charged into the capacitor C3. At this time, the anode side of D1 becomes negative voltage as compared with the ground. then

This negative voltage signal is applied to the base of the PNP transistor Q2 of the buffer / output section 103 to conduct Q2,

Maintains a logical HIGH state close to the Vcc voltage.

When a part of the body or a conductor held by the hand touches the sensing metal piece 100, a relatively large impedance is applied to the collector of Q1

The oscillator Q1 stops the oscillation and fails to generate an output because it imbalances the oscillation impedance in the circuit,

The negative voltage charged between the positive electrode plates of the positive electrode plate 102 is discharged through the body in an instant. In this way,

When the negative voltage is removed, the PNP transistor Q2 is cut off and the output terminal connected to the collector of Q2 is grounded

It becomes a logic LOW state in the vicinity. Therefore, when the whole system detects the contact of the body, the output changes from HIGH to LOW

And a signal for switching is obtained. To obtain an inverting switching signal, add another PNP transistor to the collector of Q2

If you connect the stator in the same way as Q2, you can make a reversed signal that changes from LOW to HIGH.

In this way, a switching signal can be obtained that detects a physical contact with a small number of components, and the system maintains stable operation

The R4 value of R1 and R2 of the oscillation unit 100 and the R4 value of the output unit 103 are set to an optimum value in order to minimize the standby current consumption.

The touch sensor circuit of the present invention may be manufactured as a module assembled by using each of its constituent components as an individual element,

It may be mounted as an integrated circuit in one IC. 2, a plurality of touch sensors of the present invention are provided in one IC

And a parallel detection port is constructed using the same. When a plurality of detection ports are required, the oscillating portion, the rectifying portion,

So that a plurality of touch sensor detection ports for body contact can be constructed with one IC.

Claims (1)

A single-pole sensing metal piece for sensing the presence or absence of contact of a part of the user's body or a conductor held by the user's hand,
An oscillation unit that oscillates normally at a predetermined oscillation frequency when there is no contact with the body,
A rectification section for receiving the oscillation signal output from the oscillation section and converting the oscillation signal into a DC voltage;
And an output unit for converting and outputting a logical switching signal according to an output voltage of the rectifying unit,
The oscillating unit uses one oscillating NPN transistor (Q1) as an active element for oscillating operation, and the NPN transistor
The oscillator inductor L1 is connected to the collector at a power supply voltage Vcc and the capacitor C1 is connected in parallel between the collector and the emitter
The emitter is connected to the current control resistor R1 through a ground, and a second resistor R2 for bias and a second capacitor C2 are connected to the base
The second resistor is composed of the power supply voltage Vcc and the second capacitor C2 is connected to the ground,
The sensing metal piece may include an oscillation NPN transistor for suppressing an oscillation output of the oscillation unit when there is contact with a body,
Is directly connected to the collector of the transistor Q1,
And the input of the rectifying part is connected to the collector of the oscillating NPN transistor (Q1).

The oscillating unit, the rectifying unit, and the output unit are built in a single integrated circuit (IC) as a single or a plurality,
And an output port.

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