KR20050115170A - Electrical touch sensor - Google Patents

Abstract

The present invention discloses an electrical contact sensor. The electrical contact sensor includes at least one contact pad, a contact signal generator for generating signals having different pulse widths according to whether the contact object is in contact with the contact pad, and an output signal of the contact signal generator. And a voltage generator for generating a voltage corresponding to the pulse width. Therefore, even if the conductivity is not sufficient, it is possible to accurately determine the presence or absence of a contact object having a predetermined charge accumulation ability to provide reliability of operation. In addition, it is possible to determine the contact of the contact object with only one contact pad, thereby reducing the layout of the product.

Description

Electrical touch sensor

The present invention relates to a touch sensor, and more particularly, to an electrical contact sensor that electrically detects and notifies the presence or absence of a contact object.

In general, the touch sensor is divided into a push button operating in a mechanical manner and an electrical contact sensor operating in a non-mechanical manner.

While the pushbuttons are inexpensive to produce, they require mechanical contacts to detect the user's choices and spring devices for the resiliency of the buttons, which makes it difficult to miniaturize the product and has a complex structure. The touch sensor is more expensive to produce than the push button, but offers more advantages for miniaturization.

Of particular interest in the present invention relates to electrical contact sensors.

1A to 1C are diagrams illustrating an electrical contact sensor according to the related art.

FIG. 1A is a circuit diagram of an electrical contact sensor, FIG. 1B is an operation circuit diagram of the electrical contact sensor when the contact object is not in contact, and FIG. 1C is an operation circuit diagram of the electrical contact sensor when the contact object is in contact.

With continued reference to FIG. 1A, the electrical contact sensor includes two contact pads (or contact pins) PAD1 and PAD2 with which a contact object is contacted, and a first resistor for protecting the internal circuit from static electricity transmitted from the contact object. (R1), the active element N-type FET Q1, the second resistor R2 for setting the bias voltage of the N-type FET Q1, and the third to be a load of the N-type FET Q1. A resistor RL and an output buffer B1 for buffering the output voltage of the N-type FET Q1 are provided.

When the contact object does not contact the electrical contact sensor, as shown in FIG. 1B and 1C, the contact pads PAD1 and PAD2 are opened, and thus the gate of the N-type FET Q1 is connected to the second resistor R2. It is connected to the ground voltage through.

The N-type FET Q1 connected with the ground voltage and the gate is turned off, and there is no flow of current through the N-type FET Q1 and the third resistor RL. The power supply voltage VDD is applied to the drain of the N-type FET Q1, and the output buffer B1 receives the power supply voltage VDD applied to the drain of the N-type FET Q1 to generate a "H" signal. To print.

On the other hand, when the contact object is in contact with the electrical contact sensor, the electrical contact sensor has the operation circuit diagram of Figure 1c.

The contact object at this time becomes a human finger which is generally a conductive resistor.

Referring to FIG. 1C, two contact pads PAD1 and PAD2 are connected through a resistor RH and are connected by a voltage difference between the power supply voltage VDD and the ground voltage VGND through the resistor RH. The generated current flows. Hereinafter, the resistor RH of a person connected to the contact pad will be referred to as a fourth resistor RH.

Then, a voltage of "power supply voltage VDD x second resistor R2 / (first resistor R1 + fourth resistor RH)" is applied to the gate of the N-type FET Q1.

When the voltage applied to the gate of the N-type FET Q1 is greater than the threshold voltage (Vth) of the N-type FET Q1, the N-type FET Q1 is turned on so that the N-type FET Q1 is turned on. And through the third resistor (RL) of "A × (VG-Vth) ^2" The drain current IL flows. Where A is the intrinsic constant value of each FET and Vth is the threshold voltage value of each FET.

That is, the voltage VD of " power supply voltage VDD-drain current IL x third resistor RL " is applied to the drain of the N-type FET Q1.

In particular, when a voltage is applied to the gate of the N-type FET Q1, a drain current IL, which is calculated as "drain current IL x third resistor RL> power supply voltage VDD," is applied. The drain voltage of (Q1) becomes "0".

As described above, when two contact pads PAD1 and PAD2 come into contact with a sufficiently small resistance value, a drain voltage having a value close to "0" is generated in the drain of the N-type FET Q1. The drain voltage is output as an "L" signal via the output buffer B1.

As described above, the conventional electrical contact sensor includes two contact pads, and when a conductive contact object contacts the two contact pads at the same time, it electrically detects and generates and outputs a signal accordingly.

Conventional electrical contact sensors can be applied to various electrical and electronic devices by converting the contact facts into electrical signals only by electrical contact without mechanical configuration, but two contact pads are required to detect the contact of the contact object. .

As described above, the conventional electrical contact sensor has a limitation of miniaturization by having two contact pads, and a contact object contacting the two contact pads must be a conductive object.

When a person's finger is in contact with the electrical contact pad, but the person wears a non-conductive glove or the bare surface is dry and does not have sufficient conductivity, the electrical contact sensor is shown in FIG. 2. The same output signal is generated.

That is, when the contact object does not have sufficient conductivity despite the contact object contacting the contact pads PAD1 and PAD2 (section 1, section 3), the contact pads PAD1 and PAD2 are very sensitive. The state in which the resistor having the high resistance value is connected is in the same state. Accordingly, only a small current is applied to the N-type FET Q1 so that the electrical contact sensor generates an "H" signal.

As described above, in the case of the conventional electrical contact sensor, even though the contact object is in contact, when the contact object does not have sufficient conductivity, the electrical contact sensor may not detect this and malfunction.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrical contact sensor that can detect a contact even when a contact object having insufficient conductivity is touched.

Another object of the present invention is to provide an electrical contact sensor capable of detecting the presence or absence of contact of a contact object with only one contact pad.

Still another object of the present invention is to provide a human input device that is notified of a contact object through an electrical contact sensor and is operated only when the contact object is in contact.

Electrical contact sensor of the present invention for achieving the above object and other objects is provided with at least one contact pad, the contact signal generation for generating a signal having a different pulse width in accordance with the presence or absence of contact of the contact object to the contact pad And a voltage generator for generating a voltage corresponding to the pulse width of the output signal of the contact signal generator.

In this case, the contact signal generator generates a first signal that generates a first signal and a second signal having the same phase as the first signal when the contact pad is not in contact with the contact pad. A second signal generator for generating a second signal having a delayed phase according to the capacitance component of the contact object, and a phase comparison signal generator for generating a signal having a pulse width corresponding to a phase difference between the first signal and the second signal It is characterized by including.

The human input device of the present invention for achieving the another object is a power supply for supplying operating power, an electrical contact sensor for detecting and notifying the presence or absence of contact of the contact object, and the power supply only when the contact object is in contact And a control unit configured to control the supply of the operation power, wherein the electrical contact sensor includes at least one contact pad, and generates a signal having a different pulse width depending on whether a contact object contacts the contact pad. And a voltage generator for generating a voltage corresponding to the pulse width of the output signal of the contact signal generator.

Hereinafter, the electrical contact sensor of the present invention will be described with reference to the accompanying drawings.

3 is a circuit diagram of an electrical contact sensor according to the technique of the present invention.

As shown in the figure, the electrical contact sensor 40 of the present invention includes a reference signal generator 10 for generating an alternating current (AC) signal, which is a reference signal, and one contact pad (PAD1). DC voltage corresponding to the pulse width of the output signal of the contact signal generator 20 and the contact signal generator 20 for generating signals having different pulse widths depending on whether or not the contact object contacts the pad PAD1. DC voltage generator 30 for generating a.

The contact signal generator 20 may generate the first signal when the contact object is not in contact with the first signal generator 21 that generates the first signal having the same phase regardless of whether the contact object is in contact. A second signal generator which generates a second signal having the same phase as the first signal of the unit 21 and outputs a second signal having a phase delayed in proportion to the capacitance component of the contact object when the contact object is in contact; And a phase comparison signal generator 23 for generating an output signal having a pulse width corresponding to the phase difference between the first signal and the second signal.

Accordingly, the first signal generator 21 includes a first resistor R11 and a first input buffer B11 connected in series with the reference signal generator 10, and the first signal generator 21 is a reference signal. Located between the second resistor R12 and the second input buffer B12 connected in series with the generator 10, and between the second resistor R12 and the second input buffer B12, through a separate signal line. It has a contact pad PAD1 connected thereto.

The phase comparison signal generator 23 includes an exclusive OR (XOR) XOR1, and the DC voltage generator 30 includes a third resistor R13 having a low pass filter structure. Capacitor C1 is provided.

Hereinafter, the operation of the electrical contact sensor of the present invention will be described with reference to the drawings of FIGS. 4A to 4D.

4A is an operation circuit diagram of the electrical contact sensor 40 when the contact object is not in contact, FIG. 4B is an output signal waveform diagram of the electrical contact sensor 40 when the contact object is not in contact, and FIG. 4C is a contact 4 is an operation circuit diagram of the electrical contact sensor 40 when the object is in contact, and FIG. 4D is an output signal waveform diagram of the electrical contact sensor 40 when the contact object is in contact.

First, an operation of the electrical contact sensor 40 when the contact object does not contact the contact pad PAD1 will be described with reference to FIGS. 4A and 4B.

As shown in FIG. 4A, since no contact object contacts the contact pad PAD1, the delay component of the second signal generator 22 does not increase. That is, the second signal generator 22 and the first signal generator 21 have the same reference delay component.

The AC signal applied to the first signal generator 21 of FIG. 4A is input to the first input buffer 17 through a reference delay component of the first resistor R11. The first input buffer B11 generates and outputs a first signal having the same phase as that of the input AC signal.

In addition, the AC signal applied to the second signal generator 22 also passes through the reference delay component of the second resistor R12, and then is input to the second input buffer B12, and the second input buffer B12 is input. A second signal having the same phase as that of the AC signal is generated and output.

Accordingly, the first signal and the second signal have the same phase. However, this is an output state in an ideal environment, and more often the first signal and the second signal having a slight phase difference are more often output as shown in FIG. 4B.

The XOR (XOR1) of the phase comparison signal generator 23 receives the first signal and the second signal output from each of the first input buffer B11 and the second input buffer B12, and voltage levels of the two signals. Are compared, and if the voltage levels are the same, an "L" signal is generated, and if not, an "H" signal is generated and output.

Accordingly, XOR (XOR1) generates and outputs a signal having a pulse width proportional to the phase difference between the first signal and the second signal.

At this time, since the first signal and the second signal input to XOR (XOR1) have the same or extremely small phase difference, a signal having no or extremely narrow pulse width is generated.

The capacitor C1 of the DC voltage generator 30 charges the electric charge by the pulse width of the output signal of the XOR (XOR1) transmitted through the resistor R13, so that the voltage is extremely small, that is, the voltage corresponding to the "L" level. Generates an output signal with

On the contrary, the operation of the electrical contact sensor 40 when the contact object contacts the contact pad PAD1 will be described with reference to FIGS. 4C and 4D.

As shown in FIG. 4C, when the contact object contacts the contact pad PAD1, the delay component of the second signal generator 22 is further increased by the capacitance CH of the contact object.

This is because a contact object, such as a human body, has the property and capacity of capacitance (CH) to accumulate a large amount of charge.

The first signal generator 21 receives the AC signal that has passed the reference delay component of the first resistor R11 regardless of whether the first input buffer R11 is in contact with the contact object. Generate a first signal having the same phase.

However, as the second input buffer R12 of the second signal generator 22 contacts the contact object, an AC signal that passes through the reference delay component of the second resistor R12 and the delay component of the capacitor CH, that is, is increased. An AC signal having a phase delayed by the delay component of the capacitor CH is input to generate a second signal having a phase delayed by a predetermined value from the phase of the AC signal.

More specifically, the input AC signal of the second input buffer B12 is used to delay the delayed phase, i.e., time delay, of "1 / (second resistor R12 × contact object CH)" as shown in FIG. 4D. Have Accordingly, the second input buffer R12 generates a second signal having a delayed phase of "1 / (second resistance R12 x contact object CH)" than the AC signal.

XOR (XOR1) receives a first signal having the same phase as the AC signal and a second signal having a delayed phase by "1 / (second resistance R12 x contact object CH)", and thus "1 / A signal having a pulse width equal to "(second resistance R12 x contact object CH)" is generated.

The DC voltage generator 30 then receives an output signal of XOR (XOR1) having a pulse width corresponding to the phase difference of "1 / (second resistor R12 x contact object CH)", and "1 / ( The charge is charged as much as the second resistor R12 × contact object CH " to generate an output signal having a voltage corresponding to the “H” level.

As described above, the electrical contact sensor of the present invention uses a principle that a time delay occurs in an AC signal passing through a delay component increased by the capacitance component CH of the contact object when the contact object contacts the single contact pad PAD1. .

Accordingly, the electrical contact sensor of the present invention electrically detects contact and non-contact of a contact object with only one contact pad PAD1 and generates an electrical signal corresponding thereto.

In addition, if necessary, the electrical contact sensor of the present invention may be provided with a plurality of contact pads. At this time, each of the contact pads independently increases the delay component in the delay path. When the contact object contacts a plurality of contact pads, the delay component of the delay path is increased in proportion to the number of contact pads in contact. .

FIG. 5 is a view illustrating a change in output level of the electrical contact sensor when the contact object is not in contact with the contact object of FIG. 3, and in the case where the contact object is not in contact with the electrical contact sensor. It generates a signal of "H" as shown in (1) and section (3), and generates a signal of "L" as shown in section (2) and section (4) when the contact object is in contact with the electrical contact sensor. Able to know.

In this case, when the contact object is a human, the capacitance component generated from each hand may vary slightly. When a hand generating a large amount of capacitance is touched, the electrical contact sensor 40 of the present invention generates an output signal having a large voltage difference, and accordingly, the electrical contact sensor 40 performs a stable operation.

However, when a hand generating less capacitance component is touched, the electrical contact sensor 40 of the present invention generates an output signal having a small voltage difference, and thus the electrical contact sensor 40 does not perform a stable operation. Therefore, in the present invention, by adding a separate circuit to the electrical contact sensor 40, the electrical contact sensor 40 of FIG. 3 supports to perform a stable operation at all times.

Such a circuit will be described below with reference to FIGS. 6 and 7.

FIG. 6 is a diagram illustrating a first embodiment of a digital signal generator added to the electrical contact sensor of FIG. 3. The digital signal generator of the present invention includes the electrical contact sensor 40 and the amplifier 50 of FIG. 3. And an analog comparator 60.

Accordingly, the amplifier 50 receives the output signal of the electrical contact sensor 40 and amplifies the voltage difference between the output signal at the time of contact and the output signal at the time of non-contact so that the analog comparator 60 has a predetermined range. do. The analog comparator 60 compares the output signal of the amplifier 50 with its own reference voltage and generates an "H" signal when the voltage of the output signal is greater than the reference voltage, and "L" if the voltage of the output signal is less than the reference voltage. Generates a signal.

In this case, a variable gain amplifier may be used as the amplifier 50 to adjust the gain according to external control, and the analog comparator 60 may adjust the reference voltage according to the external control.

FIG. 7 illustrates a second embodiment of a digital signal generator added to the electrical contact sensor of FIG. 3. The digital signal generator of the present invention includes an electrical contact sensor 40 of FIG. convertor 70, and a programmable level detector 80.

Accordingly, the ADC 70 receives a signal output from the electrical contact sensor 40 of FIG. 3 and converts the voltage of the received signal into a digital signal of a predetermined bit. The programmable level detector 80 compares the reference digital signal with a predetermined bit digital signal provided from the ADC 70 to generate an "H" signal when the predetermined bit digital signal is larger than the reference digital signal, If small, generates "L" signal.

In this case, the programmable level detector 80 adjusts a reference digital signal that is a criterion for determining the "H" signal or the "L" signal under external control.

8A illustrates a wireless mouse device using the electrical contact sensor of the present invention. The wireless mouse 90 includes the electrical contact sensor 91, the microcontroller unit 92, and the image sensor of FIG. 3. 93, a power supply 94, and a wireless communication interface 95 are provided.

 The MCU 92 is notified that the human hand is in contact with the wireless mouse through the electrical contact sensor 91.

The MCU 92 supplies operating power to each component only when a human hand is contacted by the electrical contact sensor 91 as shown in FIG. 8B (section (1) and section (3)). give.

Since wireless devices such as the wireless mouse 90 of FIG. 8A are limited in use time by using a rechargeable battery or a battery as a power source, it is important to extend the use time to the maximum.

Therefore, it is possible to increase the use time by turning off the power when not in use. The wireless mouse 90 of the present invention provides power to each component only when a person comes in contact to use the wireless mouse 90. It can significantly increase the usage time by preventing the waste of raw materials.

In the above, the wireless mouse using the electrical contact sensor has been limited to the wireless mouse. However, all kinds of human input devices that need to be operated only when a person comes in contact to reduce power consumption can adopt the above method. have.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below. I can understand that you can.

Therefore, the electrical contact sensor of the present invention provides a reliability of operation by allowing the contact object to accurately determine the presence or absence of contact, even if the conductivity is not sufficient, even if the contact object has a predetermined charge accumulation capability. This makes it possible to operate the electrical contact sensor stably regardless of the humidity of the weather and the presence or absence of a conductive gap between people or wearing a glove.

In addition, the electrical contact sensor can reduce the layout of the product by determining whether the contact object is in contact with only one contact pad.

In addition, when the human input device includes an electrical contact sensor, the presence or absence of contact of the contact object is notified through the electrical contact sensor, and only when the contact object is contacted, the supply of operating power reduces the power consumption drastically.

Is a circuit diagram of an electrical contact sensor according to the prior art;

FIG. 1B is an operation circuit diagram when the contact object is not in contact with the electrical contact sensor of FIG.

1C is an operation circuit diagram when a contact object is touched in the electrical contact sensor of FIG. 1A;

2 is a view showing a change in the output level of the electrical contact sensor in the electrical contact sensor of FIG.

3 illustrates a circuit diagram of an electrical contact sensor in accordance with the teachings of the present invention.

4A is an operation circuit diagram when the contact object is not in contact with the electrical contact sensor of FIG.

4B is a diagram illustrating signal waveforms in a case where a contact object does not contact in the electrical contact sensor of FIG. 3.

4C is an operation circuit diagram when a contact object contacts the electrical contact sensor of FIG. 3.

4D is a diagram illustrating signal waveforms when a contact object contacts the electrical contact sensor of FIG. 3.

5 is a view showing a change in the output level of the electrical contact sensor in the electrical contact sensor of FIG.

FIG. 6 shows a first embodiment of a digital signal generator added to the electrical contact sensor of FIG.

FIG. 7 shows a first embodiment of a digital signal generator added to the electrical contact sensor of FIG.

8A illustrates a wireless mouse device utilizing the electrical contact sensor of the present invention.

8B is a diagram illustrating a method for controlling operation power of the wireless mouse device of 8A.

Claims (13)

A contact signal generator having at least one contact pad and generating a signal having a different pulse width depending on whether a contact object is in contact with the contact pad; And And a voltage generator for generating a voltage corresponding to the pulse width of the output signal of the contact signal generator. The method of claim 1, wherein the contact signal generation unit A first signal generator for generating a first signal; A second signal generating a second signal having the same phase as the first signal when the contact pad is not in contact, and generating a second signal having a delayed phase according to the capacitance component of the contact object when the contact object is in contact. A signal generator; And And a phase comparison signal generator for generating a signal having a pulse width corresponding to a phase difference between the first signal and the second signal. The method of claim 2, wherein the first signal generator A resistor having a reference delay component; And And a buffer for generating a first signal having a phase delayed according to the reference delay component of the resistance. The method of claim 2, wherein the second signal generator is A resistor having a reference delay component; A contact pad which increases a delay component by the capacitance component of the contact object upon contact of the contact object; And The non-contact of the contact object generates a second signal having a delayed phase according to the reference delay component of the resistance, and the contact of the contact object has a delayed phase according to the resistance and an increased delay component of the contact object. And a buffer for generating a second signal. The method of claim 2, wherein the phase comparison signal generation unit Electrical contact sensor, characterized in that the exclusive OR (exclusive OR). The method of claim 1, wherein the voltage generator Electrical contact sensor, characterized in that the low pass filter. The method of claim 1, wherein the electrical contact sensor An amplifier for amplifying the output signal of the voltage generator so as to have a voltage within a predetermined range; And And a comparator for generating a logic value by comparing the voltage of the output signal of the amplifier with a reference voltage. The method of claim 6, wherein the amplifier Electrical contact sensor, characterized in that the variable gain amplifier variable the gain in accordance with the external control. The method of claim 6, wherein the reference voltage is Electrical contact sensor, characterized in that the variable according to the external control. The method of claim 1, wherein the electrical contact sensor A converter for converting the output signal of the voltage generator into a digital signal of a predetermined bit; And And a comparator for generating a logic value by comparing the digital signal of the predetermined bit with a reference digital signal. The method of claim 9, wherein the reference digital signal is Electrical contact sensor, characterized in that the variable according to the external control. A power supply for supplying operation power, an electrical contact sensor for detecting and notifying whether a contact object is in contact with the contact object, and a controller for controlling the power supply to supply the operation power only when the contact object is in contact with the contact object; The electrical contact sensor A contact signal generator having at least one contact pad and generating a signal having a different pulse width depending on whether a contact object is in contact with the contact pad; And And a voltage generator for generating a voltage corresponding to the pulse width of the output signal of the contact signal generator. The method of claim 12, wherein the contact signal generation unit A first signal generator for generating a first signal; A second signal generating a second signal having the same phase as the first signal when the contact pad is not in contact, and generating a second signal having a delayed phase according to the capacitance component of the contact object when the contacting object is in contact. A signal generator; And And a phase comparison signal generator for generating a signal having a pulse width corresponding to a phase difference between the first signal and the second signal.