KR101462226B1 - Fingerprint detecting apparatuse and method for improving fingerprint detecting - Google Patents

Abstract

One embodiment of the present invention provides a sensor pad for fingerprint detection; A bezel disposed adjacent to the sensor pad and to which a driving voltage is applied; A monitoring pad disposed in the sensor pad region for monitoring an output voltage of the sensor pad according to the driving voltage; And a compensation unit for compensating an output voltage of the sensor pad based on a magnitude of a voltage sensed by the monitoring pad.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a fingerprint detection apparatus and a fingerprint detection method for improving fingerprint detection,

The present invention relates to a fingerprint detection apparatus and method, and more particularly, to a fingerprint detection apparatus and method for improving fingerprint detection using a monitoring pad.

Since fingerprints vary from person to person, they are widely used in the field of personal identification. In particular, fingerprints are widely used in various fields such as finance, crime investigation and security as personal authentication means.

A fingerprint recognition sensor has been developed to recognize these fingerprints and identify them. The fingerprint recognition sensor is a device for recognizing a fingerprint of a finger by contacting a finger of a person, and is used as a means for determining whether or not the user is a legitimate user.

Various recognition methods such as an optical method, a thermal sensing method, and a capacitive sensing method are known as a method of implementing a fingerprint recognition sensor. Among them, the capacitive type fingerprint recognition sensor acquires the shape of the fingerprint (fingerprint pattern) by detecting the change of capacitance according to the shape of the fingerprint and the floor when the finger surface of the person touches the conductive detection pattern.

In recent years, various additional functions utilizing personal information such as finance and security have been provided not only in communication functions such as telephone and text message transmission service through portable devices, but also in the necessity of locking devices of portable devices. . In order to improve the locking effect of such a portable device, a terminal equipped with a locking device through fingerprint recognition is being developed in earnest.

On the other hand, in order for the fingerprint sensor to be mounted on a portable device, metal packaging is performed. In this case, when the fingerprint recognition sensor includes a bezel, the driving signal must be applied to the sensor pad included in the fingerprint recognition sensor through the bezel, Is dispersed into the sensor pad and the metal packed. That is, there is a problem that the drive signal to be applied only to the sensor pad is dispersed by the metal due to the metal wrapping, and the loss is generated, which affects the fingerprint sensing.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problems of the prior art.

It is also an object of the present invention to improve fingerprint detection using a monitoring pad.

In order to accomplish the above object, an embodiment of the present invention provides a sensor pad for fingerprint detection; A bezel disposed adjacent to the sensor pad and to which a driving voltage is applied; A monitoring pad disposed in the sensor pad region for monitoring an output voltage of the sensor pad according to the driving voltage; And a compensation unit for compensating an output voltage of the sensor pad based on a magnitude of a voltage sensed by the monitoring pad.

Wherein the compensation unit comprises: a comparator for comparing a magnitude of the voltage sensed by the monitoring pad and one or more reference voltages; And a gain determination unit for determining a gain for compensating an output voltage of the sensor pad using an output value of the comparator.

A plurality of output nodes of the voltage divider may be alternately connected to a reference voltage input terminal of the comparator.

The fingerprint detection device may further include a sensing circuit for outputting a signal related to whether or not the sensor pad is touched, and the gain determination unit may apply the determined gain to the sensing circuit.

Wherein the fingerprint detection device further includes a programmable gain amplifier (PGA) for amplifying an output signal of a sensing circuit for detecting whether or not the finger touches the sensor pad, and the gain determination unit determines a control value based on the determined gain, It can be reflected in the gain.

Wherein the fingerprint detection device further includes an analog to digital converter (ADC) for converting an output signal of a sensing circuit for detecting whether or not the finger touches the sensor pad to a digital signal, and the gain determination unit determines, based on the determined gain, And can be applied to the digital signal of the ADC.

The gain determination unit may determine the gain based on a magnitude of a voltage of the monitoring pad with respect to a magnitude of a reference value based on the driving voltage.

The monitoring pad may be disposed inside the sensor pad or may be spaced apart from the sensor pad by an insulating pad that is insulated from the sensor pad.

According to another embodiment of the present invention, there is provided a method of driving a plasma display panel, comprising: applying a driving voltage to a bezel; Monitoring a magnitude of an output voltage of a sensor pad that senses a subject in response to the driving voltage; Determining a gain for compensating an output voltage of the sensor pad based on the magnitude of the monitored voltage; And amplifying the output voltage of the sensor pad in accordance with the gain.

Wherein the gain determination step comprises: comparing the magnitude of the monitoring voltage and one or more reference voltages; And determining the gain using an output value according to the comparison.

Wherein the comparing step compares the one or more reference voltages output from at least one of the plurality of output nodes of the voltage divider including a plurality of resistors connected in series between the power supply terminal and the ground terminal, .

The gain determination step may include determining the gain based on a magnitude of the monitoring voltage with respect to a magnitude of a reference value based on the driving voltage.

According to an embodiment of the present invention, the output voltage of the sensor pad can be compensated through the monitoring pad disposed in the sensor pad area, thereby improving the fingerprint detection accuracy of the fingerprint detection device.

It should be understood that the effects of the present invention are not limited to the above effects and include all effects that can be deduced from the detailed description of the present invention or the configuration of the invention described in the claims.

1 is a view showing a schematic configuration of an electronic apparatus according to an embodiment of the present invention.
2 is a sectional view taken along the line AA in Fig.
FIG. 3 is a diagram showing a configuration of a fingerprint detecting apparatus according to an embodiment of the present invention.
4 is an exemplary waveform diagram for comparing the voltage of the monitoring pad with the ideal voltage at the sensor pad.
5A is a diagram showing an example of a comparator of the fingerprint detection device.
5B is a diagram for explaining the operation of the comparator of the fingerprint detection device.
FIG. 6 is an exemplary diagram illustrating a configuration of a fingerprint detection apparatus according to an embodiment of the present invention. FIG.
7 is a view for explaining a fingerprint detection method according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when a part is referred to as being "connected" to another part, it includes not only "directly connected" but also "indirectly connected" . Also, when an element is referred to as "comprising ", it means that it can include other elements, not excluding other elements unless specifically stated otherwise.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a view showing a schematic configuration of an electronic device according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line A-A of FIG.

1 and 2, the electronic device 100 may include a fingerprint detection device 10 at least in part. Although the fingerprint detection device 10 is illustrated as being formed on one edge of the electronic device 100, it is not limited thereto.

The electronic device 100 according to an embodiment of the present invention may be a digital device that performs predetermined data processing to perform a desired operation by a user. The electronic device 100 may include an input unit and a display unit 101 and may provide a status of an operation performed by a user's predetermined operation command through the input unit to the user through the display unit 101. [ The electronic apparatus 100 may include a cover glass 1200 that protects the display unit 101 and forms a front surface of the electronic apparatus 100. [

1, the display unit 101 of the electronic device 100 is implemented by a touch screen method and functions as an input unit itself. However, the input unit may be implemented by a keyboard or a keypad, for example, As shown in FIG.

The electronic device 100 according to an exemplary embodiment of the present invention includes a memory unit and is provided with a microprocessor, and is capable of being operated by a tablet PC, a smart phone, a personal computer, a workstation, a PDA, a web pad, And the like.

The fingerprint detection device 10 according to an embodiment of the present invention can be implemented as a slide type. The slide type fingerprint detection device 10 reads a fingerprint image of a finger moving in a sliding manner to read a piece of fingerprint image and then registers the fingerprint image as a single image to implement a full fingerprint image. . However, the fingerprint detecting apparatus 10 according to the embodiment of the present invention is not limited to this, and it is needless to say that the fingerprint detecting apparatus 10 may be realized by an area method in which a fingerprint is read when a finger is placed on the sensor.

The fingerprint detection device 10 includes a sensor pad 110 and a bezel 130. The bezel 130 is provided separately from the sensor pad 130. The bezel 130 functions as an antenna for transmitting a driving signal for detecting a fingerprint to a subject (finger).

1, the bezel 130 is formed in the form of a ring surrounding the sensor pad 110, but the bezel 130 may be formed to surround only a part of the sensor pad 110. The sensor pad 110 may be spaced apart from the sensor pad 110 in the form of a frame and may have a predetermined shape (for example, a reversed "U" Shape). The bezel 130 according to the embodiment of the present invention is not limited to a specific form.

The bezel 130 is formed of a conductive metal because it must send a driving signal to a subject. The fingerprint detection device 10 is mounted on the electronic device 100 by metal packaging. In this case, a driving signal outputted from the bezel 130 is dispersed to the metal packaged through the subject and the sensor pad 110 to cause loss. In order to compensate for this, the fingerprint detecting device 10 includes a monitoring pad (See FIG. 3) and a compensator 200 (see FIG. 3). This will be described later with reference to FIG.

Although the sliding method has been described above, it is to be understood that the present invention is not limited thereto and that the embodiment of the present invention is applicable to the conventional fingerprint recognition technology.

FIG. 3 is a diagram illustrating a configuration of a fingerprint detection apparatus according to an exemplary embodiment of the present invention, and FIG. 4 is an exemplary waveform diagram for comparing an ideal voltage in a sensor pad with a voltage of a monitoring pad.

Referring to FIG. 3, the fingerprint detection apparatus includes a sensor pad 110, a monitoring pad 120, a bezel 130, and a compensation unit 200.

The sensor pad 110 forms a capacitance with the fingerprint fingerprint as a patterned electrode on the substrate to detect a fingerprint input. The sensor pad 110 outputs an output voltage corresponding to the impedance of the subject in response to the driving voltage Vdrv applied to the bezel 130.

The sensor pad 110 may be formed on the substrate and may be electrically connected to the sensing circuit 231 (see FIG. 6) through the signal line 111 (see FIG. 6). At this time, the substrate may be in the form of glass or plastic film of transparent material.

The monitoring pad 120 may be disposed in the area where the sensor pad 110 is disposed so that the voltage of the sensor pad 110 and the voltage of the monitoring pad 120 are equalized when the fingerprint is detected. As described above, the monitoring pad 120 monitors the voltage of the sensor pad 110 at the time of fingerprint detection and is used as basic information of a compensation operation to be described later. The monitoring pad 120 may be electrically connected to the compensator 200 via the signal line 112.

Also, the monitoring pad 120 may be disposed inside the sensor pad 110, but not limited thereto. The monitoring pad 120 may be spaced apart from the sensor pad 110 by an insulating pad.

For example, the monitoring pad 120 may have a groove 121 formed inside the sensor pad 110, and may be disposed separately from the sensor pad 110. In another example, the monitoring pad 120 is disposed on top of an insulating pad (not shown) and the insulating pad is disposed on top of the sensor pad 110 so that the sensor pad 110 and the monitoring pad 120 are insulated As shown in Fig.

The sensor pad 110 and the monitoring pad 120 may be made of the same material. For example, when the sensor pad 110 is a transparent conductive material such as ITO, the monitoring pad 120 may be formed of the same material.

That is, the sensor pad 110 and the monitoring pad 120 may be formed of indium tin oxide (ITO), antimony tin oxide (ATO), indium zinc oxide (IZO), carbon nanotube (CNT), graphene, And the like.

The bezel 130 is disposed adjacent to the sensor pad 110, and a driving voltage Vdrv is applied thereto. The driving voltage Vdrv applied to the bezel 130 is preferably a square wave signal. The driving voltage Vdrv may be a clock signal having the same duty ratio, but may have a different duty ratio.

The compensation unit 200 compensates the output voltage of the sensor pad 110 based on the magnitude of the monitoring voltage sensed by the monitoring pad 120. To this end, the compensation unit 200 may include a comparator 210 and a gain determination unit 220. [

The comparator 210 compares the monitoring voltage sensed by the monitoring pad 120 with one or more reference voltages and outputs the result of the comparison. A plurality of output nodes of the voltage divider may be alternately connected to the reference voltage input terminal of the comparator 210. The voltage divider may include a plurality of resistors connected in series between the power terminal and the ground terminal. This will be described later with reference to Figs. 5A and 5B.

The gain determination unit 220 may determine a gain for compensating the output voltage of the sensor pad 110 based on the output value of the comparator 210. [

For example, the gain determination unit 220 may determine a gain for compensating the output voltage of the sensor pad 110 based on the output value of the comparator 210. The output value of the comparator 210 is based on the magnitude of the monitoring voltage versus the reference value. Here, the reference value may be the output voltage value of the sensor pad 110 measured before the fingerprint recognition sensor is contacted with the sensor pad 110, but is not limited thereto.

The gain determiner 220 may previously store a gain corresponding to each output value output from the comparator 210, and may determine a gain corresponding to the output value of the input comparator 210.

The gain determiner 220 can apply the determined gain to the output signal of the sensor pad 110 to amplify it, to reflect it in a PGA (Programmable Gain Amplifier), or to adjust a digital value in an ADC (Analog to Digital Converter) Which will be described later in detail.

6), and the fingerprint detecting unit can detect the fingerprint based on the output voltage of the sensor pad 110 compensated by the compensating unit 200. The fingerprint detecting unit may detect the fingerprint based on the output voltage of the sensor pad 110. [

Referring to FIG. 4, a driving voltage Vdrv of a square wave is applied to the bezel 130. An ideal voltage detected by the sensor pad 110 without a _loss of the driving voltage Vdrv, that is, a loss when the finger is touched with the fingerprint detection device, can be assumed as a reference value.

However, in practice, since the drive voltage Vdrv is dispersed by the metal package in the sensor pad 110 and the packed metal or the like, the magnitude of the output voltage of the sensor pad 110 is attenuated by the loss. Similarly, since the monitoring pads 120 are disposed together in the area where the sensor pads 110 are disposed, the monitoring voltage Vm detected by the monitoring pad 120 is also attenuated in the same manner. 4, the monitoring voltage Vm is attenuated in the vicinity of the maximum value VdrvH of the driving voltage Vdrv. However, the actual monitoring voltage Vm is the maximum value VdrvH of the driving voltage Vdrv ) And the minimum value (VdrvL).

As shown in FIG. 4, when the driving voltage Vdrv is a rectangular wave signal, in the ideal case, the maximum value of the voltage applied to the subject is kept constant at VdrvH. On the other hand, in the actual case, the monitoring voltage Vm detected by the monitoring pad 120, which is applied to the subject and is responsive to the impedance of the subject, has a _loss of V _{loss in the} vicinity of the maximum value (Vm.max) It can be seen that it is gradually attenuated. At this time, the loss of voltage may occur for various reasons such as parasitic capacitance, dispersion of driving voltage by metal packaging, leakage current in circuit design, and the like.

The maximum attenuation value V _loss of the output voltage of the sensor pad 110 can be detected by comparing the monitoring voltage Vm detected by the monitoring pad 120 with the reference value. Based on this, the compensation unit 200 determines a gain for amplifying the output voltage of the attenuated sensor pad 110, amplifies the output voltage of the sensor pad 110 according to the determined gain, Value can be compensated.

5A is a diagram showing an example of a comparator of the fingerprint detection device.

The comparator 210 compares the voltage Vdetect from the monitoring pad 120 with one or more reference voltages, respectively, and outputs an output value Vout corresponding to the result. The voltage Vdetect from the monitoring pad 120 may be a voltage whose monitoring voltage Vm is converted by a predetermined resistor Rx and the resistor Rx may be a resistor having a preset resistance value, And may be a parasitic resistance value generated by a circuit design. When the resistor Rx is omitted, the monitoring voltage Vm is directly input to the comparator 210. [

The comparator 210 may compare the voltage Vdetect from the monitoring pad 120 and one or more reference voltages VT [N-1: 0]. To this end, a voltage (Vdetect) from the monitoring pad 120 is input to the first input terminal of the comparator 210, and a plurality of output nodes of the voltage divider 211 are alternately connected to the second input terminal. The voltage divider 211 may include a plurality of resistors connected in series between the power supply terminal Vdd and the ground terminal.

The power supply Vdd of the voltage divider 211 is supplied to a plurality of resistors and is distributed to one or more reference voltages. As the power source Vdd, the power source voltage of elements mounted inside the fingerprint detection device may be used as it is, or it may be used as a voltage converted by level shifting or the like.

One or more reference voltages distributed by a plurality of resistors are inputted to the comparator 210 alternately. The number of reference voltages can be varied according to how many bits of the output value of the comparator 210 are divided. When the number of reference voltages is N, the output value of the comparator 210 may be log ₂ N bits. For example, when the reference voltage of the comparator 210 is four, a 2-bit signal such as '00', '01', '10', or '11' is output as an output value of the comparator 210.

For example, as shown in FIG. 5B, in order to detect the magnitude of the voltage Vdetect from the monitoring pad 120 in four stages, the number of reference voltages, that is, the N value should be four, The output value of the comparator 210 is output in 2 bits. If the voltage Vdetect from the monitoring pad 120 is larger than the reference voltage VT [2], the most significant bit value of the output value of 2 bits becomes '1', and if it is smaller than the reference voltage VT [2] . If the voltage Vdetect from the monitoring pad 120 is larger than the reference voltage VT [2] and greater than the reference voltage VT [3], the least significant bit value becomes '1', and the final output value Vout ) Becomes " 11 ". Conversely, if it is larger than the reference voltage VT [2] but smaller than the reference voltage VT [3], the final output value Vout of the comparator 210 becomes '10'.

The distribution interval between the reference voltages may be set constant between the maximum value and the minimum value of the voltage (Vdetect) from the monitoring pad 120. However, since the purpose is to measure the attenuation value (V _loss ) For example, the closer the reference voltage is to the maximum value (Vm.max), the finer the distribution interval between reference voltages can be. However, the present invention is not limited to this, and it is possible to appropriately select the values of the resistors included in the voltage divider 211 to produce a desired reference voltage.

Although FIG. 5A illustrates an embodiment including only one comparator 210, it may be implemented as a plurality of comparators 210 according to the number of reference voltages.

The gain determiner 220 (see FIG. 3) may determine a gain for compensating the output voltage of the sensor pad 110 based on the output value Vout of the comparator 210. Since the magnitude of the monitoring voltage Vm can be known through the output value Vout of the comparator 210, the ideal output voltage of the sensor pad 110 can be compared with the gain of the sensor pad 110, Can be determined.

In this case, the gain determiner 220 may store a voltage value or a gain to be applied for each binary signal according to the output value of the comparator 210 in advance. The gain determiner 220 may previously store a voltage value to be matched for each binary signal according to an output value of the comparator 210 or a control value for a gain to be applied. Hereinafter, an embodiment will be described in which the fingerprint detecting device detects the magnitude of the voltage of the monitoring pad 120 and compensates the output voltage of the sensor pad 110 using the detected voltage.

6 is a block diagram showing a schematic configuration of a fingerprint detection apparatus according to an embodiment of the present invention.

The configurations of the sensor pad 110, the monitoring pad 120, and the bezel 130 are the same as those described with reference to FIG.

The gain determination unit 220 determines a gain based on the output value of the comparator 210 and applies a determined gain to the sensing circuit 231 that determines whether or not each of the sensor pads 110 is touched .

According to another embodiment, the gain determination unit 220 may transmit a control value to a PGA (Programmable Gain Amplifier) 232 that amplifies an output signal from the sensing circuit 231 and reflect the control value to the gain of the PGA 232 .

Alternatively, according to another embodiment, the gain determination unit 220 may transmit a control value to an ADC (Analog to Digital Converter) 233 that converts the output signal of the PGA 232 into a digital signal, and may adjust the output digital value .

The sensing circuit 231 is a circuit for detecting whether or not a subject (for example, a finger) is in contact with the sensor pad 110. A plurality of sensor pads 110 are actually provided to form a sensor array. A ridge of the finger is located on any sensor pad 110 and a finger of the finger is positioned on any sensor pad 110. [ And the sensor pad 110 in contact with the ridge of the finger outputs a signal corresponding to the contact. For example, if a predetermined signal is applied after the sensor pad 110 is floated, different signals are output when the sensor pad 110 is not in contact with the sensor pad 110, thereby determining whether the sensor pad 110 is in contact with the object. Specifically, if two adjacent sensor pads 110 output a contact signal and a non-contact signal, they can be determined as regions corresponding to ridges and valleys of the fingerprint, respectively.

According to one embodiment, the gain determiner 220 can determine the gain by the process as described in FIGS. 1 to 6 and apply the determined gain to the output signal of the sensing circuit 231. FIG.

Meanwhile, the PGA 232 is a component that allows an amplifier or an amplification factor to be selected as needed through a programming method. As described above, the sensing circuit 231 outputs different signals for each of the sensor pads 110 according to whether or not the finger is in contact with the finger, and thus can grasp the ridge and the shape of the fingerprint. The difference between the output signal of the sensor pad 110 touching the ridge of the finger and the output signal of the sensor pad 110 touching the valley can be increased because the function of amplifying the output signals of the sensing circuit 231 is increased.

That is, according to another embodiment, the gain determination unit 220 may apply the output signal amplification rate of the sensing circuit 231 by inputting the control value serving as a basis of the gain determined in the above-described process to the PGA 232 .

On the other hand, the ADC 233 converts the analog signal output from the PGA 232 into a digital signal. According to yet another embodiment, the gain determination unit 220 applies the gain determined by the above-described process to the ADC 233, so that when the analog signal is converted into the digital signal, the amplified signal is output according to the gain Can be done.

That is, the gain determination unit 220 may apply the determined gain to at least one of the sensing circuit 231, the PGA 232, and the ADC 233. [

7 is a view for explaining a fingerprint detection method according to an embodiment of the present invention.

Hereinafter, a fingerprint detection method according to an embodiment of the present invention will be described with reference to FIGS. 6 and 7. FIG.

First, a driving voltage is applied to the bezel 130 (S710). The driving voltage may be a square wave signal according to the embodiment.

When a drive voltage is applied to the bezel 130 in the fingerprint detection operation, the output voltage from the subject sensing is detected from the sensor pad 110 as a response thereto. The same output voltage Vm as that of the sensor pad 110 is detected through the monitoring pad 120 insulated from the inside or the outside of the sensor pad 110. The output voltage Vm from the monitoring pad 120 The magnitude of the output voltage of the sensor pad 110 is monitored by checking the size (S720). The magnitude of the output voltage from the monitoring pad 120 can be measured through comparison with at least one reference voltage output from the voltage divider 211 (see FIG. 5A).

By knowing the magnitude of the output voltage from the monitoring pad 120, it is possible to know how much the voltage is attenuated compared to the ideal case. The ideal case refers to a case where the response voltage of the sensor pad 110 with respect to the driving signal supplied to the bezel 130 is outputted without being attenuated.

If the degree of attenuation (V _loss ) is known, it is possible to determine how much the output voltage of the sensor pad 110 is compensated for. That is, in the ideal case, the gain to be applied to the output voltage of the sensor pad 110 may be determined based on the contrast attenuated amount (S730).

If the gain is determined, the determined gain is utilized for amplifying the output voltage of the sensor pad 110 (S740).

The determined gain may be applied to the output voltage of the sensing circuit 231 which detects whether or not each of the sensor pads 110 is touched or may be applied to the PGA 232 that amplifies the output voltage of the sensing circuit 231, Or an ADC 233 that converts an output signal from the amplifier 232 into a digital signal.

Conventionally, since the fingerprint detection device is mounted on the mobile communication terminal, the output voltage of the sensor pad is lost due to metal packaging, and it is difficult to accurately detect the fingerprint.

However, according to the present invention, by using a monitoring pad for monitoring the output voltage of the sensor pad, the output voltage of the sensor pad attenuated by the loss due to metal packaging or the like is compensated for, thereby improving the accuracy of fingerprint detection.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

100: Electronic device
101:
110: Sensor pad
111: Signal wiring
120: Monitoring pads
130: Bezel
200:
210: comparator
211: Voltage divider
220:
231: sensing circuit
232: PGA
233: ADC

Claims (12)

A bezel to which a driving voltage is applied;
A sensor pad for outputting a response signal from a finger according to application of driving voltage from the bezel;
A monitoring pad disposed in the sensor pad region in an insulated manner from the sensor pad and outputting a response signal from the finger according to application of the driving voltage; And
And a compensating section for compensating an output voltage of the sensor pad through a gain determined based on a magnitude of a response signal from the monitoring pad.
The method according to claim 1,
Wherein the compensation unit comprises:
A comparator for comparing the magnitude of the voltage sensed by the monitoring pad and one or more reference voltages; And
And a gain determination unit that determines a gain for compensating an output voltage of the sensor pad using the output value of the comparator.
3. The method of claim 2,
And a plurality of output nodes of the voltage divider are alternately connected to a reference voltage input terminal of the comparator.
3. The method of claim 2,
Further comprising a sensing circuit for outputting a signal related to whether or not the sensor pad is touched,
And the gain determining section applies the determined gain to the sensing circuit.
3. The method of claim 2,
Further comprising a Programmable Gain Amplifier (PGA) for amplifying an output signal of a sensing circuit for detecting whether or not the sensor pad is touched,
And the gain determining unit reflects a control value based on the determined gain to the gain of the PGA.
3. The method of claim 2,
Further comprising an ADC (Analog to Digital Converter) for converting an output signal of a sensing circuit for detecting whether or not the sensor pad is touched to a digital signal,
Wherein the gain determining unit reflects the control value based on the determined gain and applies the digital signal to the ADC.
3. The method of claim 2,
Wherein the gain determining section determines the gain based on a magnitude of a voltage of the monitoring pad with respect to a magnitude of a reference value based on the driving voltage.
The method according to claim 1,
Wherein the monitoring pad is disposed to be spaced apart from the sensor pad or spaced apart by an insulating pad that is insulated from the sensor pad.
Applying a driving voltage to the bezel;
Monitoring a magnitude of an output voltage of a monitoring pad which is disposed in an insulated manner from a sensor pad for outputting a response signal from a finger according to application of the driving voltage and outputs a response signal identical to the sensor pad;
Determining a gain for compensating for an output voltage of the sensor pad based on a magnitude of an output voltage from the monitoring pad; And
And amplifying the output voltage of the sensor pad according to the determined gain.
10. The method of claim 9,
Comparing the magnitude of the monitoring voltage and one or more reference voltages; And
And determining the gain using an output value according to the comparison.
11. The method of claim 10,
And comparing the magnitude of the monitoring voltage with the one or more reference voltages output from at least one of the plurality of output nodes of the voltage divider including a plurality of resistors connected in series between the power terminal and the ground terminal , Fingerprint detection method.
10. The method of claim 9,
And determining the gain based on a magnitude of the monitoring voltage relative to a magnitude of a reference value based on the drive voltage.

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