CN2938571Y

CN2938571Y - Electric load tranfer device, touch induction device

Info

Publication number: CN2938571Y
Application number: CN 200620138290
Authority: CN
Inventors: 李志谦
Original assignee: BEIJING SIGMA HEXIN MICRO-ELECTRONIC TECHNOLOGY Co Ltd
Current assignee: BEIJING SIGMA HEXIN MICRO-ELECTRONIC TECHNOLOGY Co Ltd
Priority date: 2006-04-19
Filing date: 2006-09-20
Publication date: 2007-08-22
Anticipated expiration: 2016-09-20

Abstract

The utility model discloses a charge transfer device and further provides a touch induction device, comprising an induction point that can generate inductive capacity; a power supply, used to charge the inductive capacity generated by the sensing point via a first switch periodically; a second capacitor, used to transfer the charge built up by the distributed capacitance onto the second capacitor; a comparer, used to compare the voltage on the second capacitor with the reference voltage; a counter; a processor; and a third switch. The device of the utility model can measure the action of touch induction precisely.

Description

Charge transfer device and touch sensing device

Technical Field

The utility model relates to a charge transfer device further relates to a touch-sensitive device who carries out touch-sensitive with charge transfer device, and the device can be applied to various touch switch that integrate.

Background

At present, most of the implementation schemes of the tact switch adopt a capacitance measurement method. In current capacitive sensing touch switches, the basic principle is to transfer the charge on an unknown capacitance and then measure the amount of charge to determine the size of the unknown capacitance. This method has the following disadvantages:

1. the stability is poor, and because unknown electric capacity receives external disturbance, the electric charge volume can obviously change, and the electric charge volume often can not reflect the size of unknown electric capacity.

2. The cost is high, high-precision ADC is needed for measuring the charge, the circuit structure is complex, and the cost is increased.

SUMMERY OF THE UTILITY MODEL

In order to solve the above disadvantages, the present invention provides a touch switch with low cost, low power consumption, adjustable sensitivity and low false triggering rate, which is not enough for the prior art.

According to the above object, the present invention provides a charge transfer device, including:

the circuit comprises a first capacitor, a second capacitor, a power supply, a first switch and a second switch;

the power supply is connected to the first switch and used for periodically charging the first capacitor through the first switch;

the second capacitor is connected to the first capacitor through the second switch, and is used for periodically transferring the charges accumulated by the first capacitor to the second capacitor.

Wherein,

the first switch and the second switch are controlled to be switched on and off through non-overlapping clocks.

The utility model further provides a touch-sensitive device, include:

an inductive point capable of generating an inductive capacitance;

the power supply is connected to a first switch and used for periodically charging the induction capacitor generated by the induction point through the first switch;

and the second capacitor is connected to the distributed capacitor of the sensing point through a second switch and is used for periodically transferring the charges accumulated by the distributed capacitor to the second capacitor.

The comparator is used for comparing the voltage on the second capacitor with the reference voltage;

a counter;

a processor;

a third switch;

when the comparator is turned over, an overturning signal is generated and output to the third switch and the counter;

the third switch is closed after receiving the turning signal and is used for discharging the second capacitor, and the third switch is opened after the discharging is finished;

the counter stops counting after receiving the turnover signal and transmits the count value to the processor;

and after receiving the count value, the processor judges whether the key is in a touch state or a non-touch state according to the received value of the counter, returns a signal to clear the counter, and then the counter restarts counting.

Wherein,

the sensing points are composed of PCB routing lines.

Wherein

And the processor compares the counting value with a preset non-touch key value, if the difference value is greater than a preset standard difference value, the key is considered to be in a touch state, and if not, the key is considered to be in a non-touch state.

Wherein,

the value of the reference voltage is less than one-half of the charging voltage.

Wherein,

the first switch and the second switch are one of an MOS tube, a triode, a relay and an optical coupler.

Other features, objects and effects of the present invention will become more apparent and understood from the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.

Drawings

Fig. 1 is a basic schematic diagram of a touch sensing device according to the present invention;

FIG. 2 is a diagram of non-overlapping clock signals;

FIG. 3 is a schematic diagram of a touch sensing point PCB and equivalent capacitance;

FIG. 4 is another example of several other touch sensitive point PCB forms;

fig. 5 is a diagram of a reference voltage realized by using resistance voltage division.

Throughout the above drawings, the same reference numerals indicate the same, similar or corresponding features or functions.

Detailed Description

Fig. 1 is a schematic diagram of a touch sensing system according to the present invention. As shown, it includes: induction point 1, charge transfer device 2, comparator 3, counter 4, processor 5, third switch S3.

The sensing point 1 is used to sense the capacitance between different environments and ground (gnd), thereby generating a sensing capacitance Cs. The sensing point 1 can be formed by a PCB trace, and the PCB trace can be made into the shape shown in fig. 2 or the shape shown in fig. 3, so as to form a correct sensing capacitor and ensure the reliability of the sensing action.

Since the capacitance Cs generated at the sensing point 1 is small, the amount of charge transferred per time is small, and thus it is difficult to measure. The utility model provides a can carry out the electric charge transfer device that accumulates with electric charge amount, it is through constantly charging and charge transfer to induction point 1 to convert to voltage that can measure.

The charge transfer device 2 includes a first switch circuit S1, a second switch circuit S2, and a capacitor Cc 21. The switch circuits S1 and S2 can be realized by MOS tubes, triodes, relays, optocouplers and the like. The switching circuits S1, S2 are controlled to be turned on and off by non-overlapping clocks as shown in fig. 3. Thus, by periodically turning on and off the switches S1 and S2, the capacitance Cs of the sensing point 1 is accumulated to a sufficient amount of charge and the accumulated charge is entirely transferred to the capacitance Cc21, thereby causing a measurable voltage VCc to be reached at the capacitance Cc 21.

The correlation is calculated as follows:

setting the charging voltage of Cs to V_DDAn amount of electric charge of

CsV_DD

Therefore, after the first charge and discharge

(Cs+Cc)V₁＝CsV_DD，

V₁Is the voltage on Cc;

the working process is as follows: each time S1 turns on, the capacitance Cs of the inductive point 1 passes the charging voltage V_DDStarting charging; after switch S1 is turned off, due to non-overlapping clocking, switch S2 is turned on, thereby transferring the charge of capacitor Cs of sensing point 1 to capacitor Cc 21. This is done through a plurality of periodic charge transfers, so that the charge accumulated on the capacitance Cs of the inductive point 1 is transferred to the capacitance Cc21

The charge on the capacitor Cc21 is converted into a voltage and input to the comparator 3 for comparisonThe input terminal of the device 3 is a reference voltage V_refThis is compared with the voltage VCc of the capacitor Cc21, and the result of the comparison results in a control signal for the counter 4. Reference voltage V_refThis can be achieved by using resistive voltage division, as shown in fig. 5.

When the comparator 3 is inverted, an inverted signal is generated and output to the third switch S3 and the counter 4;

the third switch S3 is closed after receiving the turning signal, and is used for discharging the second capacitor, and after the discharging is finished, the third switch S3 is opened;

the counter 4 stops counting after receiving the turnover signal and transmits the count value to the processor 5;

and after receiving the count value, the processor 5 judges whether the key is in a touch state or a non-touch state according to the received value of the counter, returns a signal to zero the counter, and then restarts counting.

In the present embodiment, the comparator 3 generates a reference voltage V for comparison at its input_refThe value is designed to be less than one half of the voltage per charge, i.e. less than V_DD/2, because if the reference voltage value is high, some systematic error is introduced.

If a touch action occurs, the sensing point 1 can sense the capacitance between a human body and the ground, according to the method, the sensing capacitance Cs at the sensing point 1 is accumulated and converted into the voltage VCc of the capacitance Cc21 continuously through charge transmission and accumulation in the same way, when the VCc exceeds the reference voltage Vref of the comparator, the comparator is turned over to send a stop signal, and the counter 4 stops counting, so that a new count value, namely new capacitance charging time when the touch occurs, is obtained.

The value of the counter 4 is input into the processor 5, the processor 5 calculates the difference value according to the input value of the counter and the charging time value set by the system when no touch occurs, and when the difference value is larger than the standard difference value preset by the system, the processor 5 judges that the current state is the key press. Those skilled in the art will appreciate that the standard deviation value can be set according to hardware parameters of the system.

In this way, whether or not a touch operation has occurred is determined by detecting whether or not the value of the counter has changed.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, a plurality of modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. A charge transfer device, comprising:

2. The apparatus of claim 1, wherein:

3. A touch-sensitive apparatus, comprising:

an inductive point capable of generating an inductive capacitance;

a counter;

a processor;

a third switch;

4. The apparatus of claim 3, wherein:

5. The apparatus of claim 3, wherein:

the sensing points are composed of PCB routing lines.

6. The apparatus of claim 3, wherein:

7. The apparatus of claim 3, wherein:

8. The apparatus of claim 3, wherein: