CN100426211C - Touch type induction system - Google Patents

Abstract

The invention provides a touch sensing device. The device includes: a differential signal source, which generates two AC signals with the same frequency and opposite phases; two conductors, respectively connected to the positive and negative input ends of the differential signal source; The noise generated when it is located between the two conductors and forms two capacitors with it; a signal source has two output terminals, and the two output terminals are respectively connected to the two amplifiers through two load circuits The input terminals are connected to form a common mode input of the amplifier; the amplifier amplifies the signal flowing through the amplifier. By using the device, the sensitivity of sensing object noise can be improved, the circuit is simple, and the cost can be reduced.

Description

Touch Sensing Device

【Technical field】

The invention relates to a touch sensing device, in particular to a sensing device for sensing object noise through touch.

【Background technique】

Various types of sensing devices exist and are used in computer systems and other applications, the most familiar of which is the computer "mouse". Although the mouse is extremely common as a position-pointing device, it has mechanical parts and requires a flat surface on which the position ball can roll, and, in order to have a reasonable resolution, the mouse usually needs to roll a long distance. Finally, the mouse needs The user raises his hand to cause the cursor to move, thereby interfering with the main purpose of people typing from a computer.

Various attempts have been made to provide a means for detecting the position of a thumb or other finger used as a pointing device instead of a mouse, the desirable characteristics of which are low power consumption, high resolution and low cost. There are various types of touch sensing devices, such as resistive, inductive and capacitive.

For example, the patent No. 6534970 issued by the U.S. Trademark and Patent Office on March 18, 2003 discloses a rotary position detection technology using inductive technology. The technology includes two parts. The rotational movement of the rotating motion produces a changing magnetic field, and the second part includes two inductors used to sense the magnetic field generated by the first part and generate a corresponding signal, which changes with the relative angle between the first part and the second part, then The relative position of the first part and the second part can be measured according to the changing signal.

Such as the patent No. 6,545,614 announced by the U.S. Trademark and Patent Office on April 8, 2003. It discloses a resistance sensing device, which includes an oscillating circuit unit and an electronic node unit, the oscillating circuit unit provides a high frequency signal for the electronic node unit, if the detector detects the touch of an object such as a finger, The impedance of the electronic node unit will change accordingly. When the finger touches the electronic node, the resistance generated matches the resistance of the input end of the electronic power saver, and the reflected wave becomes smaller. By detecting the reflected wave and comparing it with a discriminator unit, if The decrease in reflectivity confirms that the object is touched.

Another example is the patent No. 5,495,077 issued by the U.S. Trademark and Patent Office on February 27, 1996, which discloses a capacitive position sensor. Has a characteristic capacitance. The capacitance will change with the touch of the object or the movement of the object relative to the sensing matrix, and the change in capacitance of each intersection point in the X and Y directions in the matrix is converted into a voltage in the X and Y directions, and these voltages After processing by the analysis circuit, an electronic signal representing the center position of the object is generated.

Although the above-mentioned patented technology has been improved in performance, such as fast response speed, high resolution, and simple operation, its structure and circuit are relatively complicated, the production cost is also high, and its power consumption is large, and the accuracy of finger sensing Not high prone to misuse.

【Content of invention】

Based on the above, the object of the present invention is to provide a touch sensing device, which can sense the noise of an object through touch, so as to realize the desired function.

The object of the present invention is achieved through the following solutions, providing a touch sensing device. The device includes: a differential signal source, two conductors, an inductor, a signal source and an amplifier. The differential signal source generates two AC signals with the same frequency and opposite phases; the two conductors are respectively connected to the positive and negative input terminals of the differential signal source; the inductor is used to receive the Noise, which is located between the two conductors and forms a capacitance with one of the conductors; the amplifier is used to amplify the signal flowing through the amplifier; the signal source has two output terminals, one output terminal One end of a first load circuit is connected, the other end of the load circuit is connected to an input end of the amplifier, the other output end of the signal source is connected to a second load circuit, and the second load circuit and the inductor are jointly connected to the The other input terminal of the amplifier, the voltage of the two input terminals of the amplifier is equal, which constitutes the common mode input of the amplifier. When an object touches the sensor, the noise of the object sensed by the sensor makes the input of the amplifier non-common mode input, there will be a signal flowing through the amplifier, the device also includes a differential signal source and two conductors, the two conductors are respectively connected to the positive and negative output terminals of the differential signal source, the inductor is located at two Between two conductors, and form two capacitors with two conductors.

Compared with the prior art, the touch sensing device can effectively reduce the influence of noise in the surrounding environment on the sensing device, and its simple circuit can also reduce the manufacturing cost.

【Description of drawings】

FIG. 1 is a circuit diagram of an embodiment of a touch sensing device.

【Detailed ways】

Please refer to FIG. 1 , which is a circuit diagram of an embodiment of a touch sensing device. The touch sensing device includes a differential signal source 11, two conductors 12, an inductor 13, a signal source 14, a first load circuit 18, a second load circuit 19, an amplifier 15, a detector 16 and a signal processing circuit 17. In this embodiment, the first load circuit 18 can be composed of a capacitor C and a first resistor R1, and the second load circuit 19 can be composed of a second resistor R2. The positive and negative poles of the differential signal source 11 are respectively connected to one of the conductors 12 , and the inductor 13 is located between the two conductors 12 to form a capacitor with one of the conductors 12 . The signal source 14 has two output terminals, one of which is connected to the second resistor R2, the second resistor R2 and the inductor are commonly connected to one input terminal of the amplifier 15, and the other output terminal of the signal source 14 Connect the first resistor R1, the first resistor R1 and the capacitor C are connected to the other input end of the amplifier 15, one end of the capacitor C is grounded, the output end of the amplifier 15 is connected to the input end of the detector 16, The output end of the detector 16 is connected to the signal processing circuit 17 .

The differential signal source 11 is used to generate two AC signals with equal frequencies and opposite phases. In the environment where the touch sensing device is located, there will be noise effects, and these noises can be generated by some charged objects, such as lamp tubes , computer, etc. These noises are signals with irregular waveforms. When these noises act on the above-mentioned capacitance formed by the differential signal source 11 and the two conductors, since the two conductors 12 are respectively connected to the positive pole and the negative pole of the differential signal source 11, then through the two capacitances The positive half-wave of the noise can be canceled by the signal generated by the negative pole of the differential signal source 11, and the negative half-wave of the noise passing through the two capacitors can be canceled by the signal produced by the positive pole of the differential signal source 11, which can reduce The impact of ambient noise on the circuit of the sensing device. The two output terminals of the signal source 14 are respectively connected to the first load circuit 18 and the second load circuit 19, to provide signals of the same magnitude and phase for the two load circuits 18, 19, and can adjust the first resistor R1, the second load circuit The size of the two resistors R2 and capacitor C makes the voltages of the two input terminals of the amplifier 15 equal to form a common mode input, so that the circuit of the sensing device is in a balanced state, and the amplifier 15 has no signal output. When the object touches the sensor 13, the sensor 13 senses the noise of the object, which makes the voltage of the input terminal of the amplifier 15 connected to the sensor 13 change, and the noise of the object sensed by the sensor 13 makes the amplifier The input of 15 is a non-common-mode input, thereby destroying the balance state before touching, and some signals will flow through the amplifier 15, and after the signal is amplified by the amplifier 15, it is easier to be detected by the detector 16. In this way, the touch of the object can be determined according to the change of the signal detected by the detector 16 before and after the touch of the object. Finally, the signal generated when the object is touched can be further processed through the signal processing circuit 17 to realize corresponding functions, wherein, when the object touches the sensor 13, it can directly touch the sensor 13 or pass through other objects, such as Insulators such as plastic sheets.

Claims (5)

1. touch type inductor comprises: an amplifier, a first input end and one second input end are arranged, and be used to amplify the signal of this amplifier of flowing through; One inductor is connected in second input end of this amplifier, is used to receive the noise that produces when object touches; One signal source has one first output terminal and second output terminal, and being used for provides input signal to first and second input end of this amplifier; One first load circuit is connected between the first input end of first output terminal of this signal source and this amplifier; One second load circuit is connected between second input end of second output terminal of signal source and this amplifier; When inductor is not touched, two input ends of this amplifier constitute the common mode input, when this inductor is touched, the noise of the object that this inductor received makes the non-common mode input of being input as of this amplifier, then the signal that is produced by this non-common mode input amplifies back output through this amplifier, it is characterized in that, this device also comprises a differential signal source and two electric conductors, these two electric conductors link to each other with positive and negative two output terminals of this differential signal source respectively, this inductor and constitutes two electric capacity with two electric conductors between two electric conductors.

2. touch type inductor as claimed in claim 1, it is characterized in that, this first load circuit can be made of electric capacity and one first resistance, and wherein this first resistance links to each other with this signal source, and this electric capacity and this first resistance are connected to an input end of this amplifier jointly.

3. touch type inductor as claimed in claim 1 is characterized in that, this second load circuit can be made of one second resistance.

4. touch type inductor as claimed in claim 1 is characterized in that, also comprises a detector, is connected in the output terminal of this amplifier, is used to detect the signal by this amplifier output.

5. touch type inductor as claimed in claim 4 is characterized in that, also comprises a signal processing circuit, is connected in the output terminal of this detector, is used to handle the signal of this detector detecting.

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