KR20040095920A - Unit pixel for capacitive semiconductor fingerprint sensor using locally-adaptive image enhancement scheme and fingerprint sensing device using the same - Google Patents

Abstract

PURPOSE: A unit pixel of a capacitive typed fingerprint sensor using a location adaptation image enhancement scheme and a fingerprint detector using the same are provided to obtain a fingerprint image more correctly by analyzing diverse brightness on a surface of a finger. CONSTITUTION: A detector(20) senses the fingerprint image. A switched-capacitor amplifier(21) uses output of the detector and a reference value as different inputs, amplifies a variance of a voltage level corresponding to the stored charges detected by the detector through the variance of the reference voltage, and outputs the amplified variance through an output terminal. A row/column direction connector(22) obtains the fingerprint image through the location adaptation image enhancement scheme making the output terminals of the unit pixels neighboring in the row/column direction commonly connected to the output terminal, obtaining a local reference value through the average including the output and the output of the connected neighboring unit pixels, and comparing the values of the output terminal by using the local reference value.

Description

Unit pixel of capacitive fingerprint sensor using local adaptive image reinforcement technique and fingerprint detection device using the same

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor fingerprint sensor, and more particularly, to a unit pixel of a capacitive fingerprint sensor using a localized image enhancement technique and a fingerprint sensor using the same.

Fingerprints have been the most widely used among the various fields of biometrics because of their high identification rate, security and stability, and they now hold substantially enough individual data. In recent years, as fingerprint recognition technology is automated, a fingerprint recognition system that acquires fingerprints in real time has been required.

As fingerprint sensors have recently been introduced, low-cost sensors have been applied to special computer devices such as keyboards, mice, and other personal computer peripheral devices. Therefore, in order to participate in such a market, it is necessary to secure a fingerprint sensor technology that is easy to use and small, low power, low cost and high definition.

Many methods have been studied to detect fingerprints electrically over the last few decades. Among the published methods, the major fingerprint detection methods are generally optical type, thermal type and capacitive type. And the like.

In the early optical method, the reflected light is captured by the opto-electric element when the surface of the finger is illuminated by using visible light or infrared light to obtain a fingerprint image. However, since this method requires an optical device and a photoelectric device separately, its use range is limited due to the volume problem. In particular, in order to be applied to a small peripheral device or a smart card, a method capable of manufacturing a small chip is required.

On the other hand, the thermal sensing method uses a pyroelectric material in the semiconductor process to convert the temperature difference between the valley of the fingerprint and the floor into a voltage difference to obtain a fingerprint image. Receives less.

However, in order to detect the temperature change in this manner, a finger must be scanned on the surface of the sensor in a one-dimensional array rather than a two-dimensional array because of the principle of operation. There is a disadvantage that the obtained image may appear differently depending on the speed and the scanning pressure.

Finally, the capacitive type uses the principle that the capacitance varies depending on the distance between the two electrodes, and the capacitance generated between the sensing electrode and the valley of the fingerprint, and the capacitance generated between the sensing electrode and the floor of the fingerprint. The fingerprint image can be obtained by recognizing the floor and the valley of the fingerprint through the difference in capacity.

The capacitive type can be implemented by using standard complementary metal oxide semiconductor (CMOS) process technology, which is simple in structure, requires no additional equipment and special process, and has advantages of small size, low power, and low cost.

However, in the capacitive fingerprint sensor, a fingerprint image of various contrasts appears according to the state of the finger surface, and it is difficult to accurately analyze it, and thus, it is impossible to obtain a fingerprint image of the required level for identification. This happens.

In order to solve the problems of the prior art as described above of the present invention, to provide a capacitive semiconductor fingerprint sensor using a localized image reinforcement technique that can obtain a fingerprint image more accurately by analyzing various brightness of the finger surface Its purpose is to.

1 is a graph illustrating the effect of local adaptation according to various finger surface conditions.

2 is a circuit diagram illustrating a unit pixel structure of a capacitive fingerprint sensor according to an embodiment of the present invention, which is proposed for reinforcing a fingerprint image.

3 is a timing diagram illustrating the operation of FIG. 2;

4 is a block diagram illustrating a form in which a local region is selected in a pixel array including a plurality of unit pixels of FIG. 2.

5 is a block diagram illustrating a capacitive fingerprint sensing device using unit pixels according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

20 detection unit 21 amplification unit

22: row and column connection

In order to achieve the above object, the present invention, the sensing unit for sensing the fingerprint image; The output of the sensing unit and the reference voltage are respectively different inputs, and the switched capacitor type amplification outputs through the output stage by amplifying a change in voltage level corresponding to the stored charge sensed by the sensing unit through the change of the reference voltage. part; And controlling the output terminals and the output terminals of the unit pixels neighboring each other in a row direction and a column direction by a predetermined number to be commonly connected to each other, and using an average value including its output and the outputs of the connected neighboring unit pixels. It provides a unit pixel of the capacitive fingerprint sensor comprising a row and column directional connection to obtain a fingerprint image through a localized image enhancement technique that compares the value of the output using the local reference value.

The present invention also provides a pixel array comprising a plurality of unit pixels; A row direction area area selection unit for outputting the area area selection signal in the row direction to determine the number of neighboring unit pixels in the row direction to obtain the area reference value; A column direction area selection unit configured to output the column area selection signal in the column direction to determine the number of neighboring unit pixels in the column direction to obtain the area reference value; A row selector which selects one row of the pixel arrays and transfers the data to the bus line; A storage and transmission unit for transmitting and storing the data transmitted through the bus line; A column selector which specifies a column of the pixel array to sequentially output the data temporarily stored in the transfer and storage unit; And an output unit selected by the heat selector to amplify and output the data transmitted from the storage and transfer unit.

The present invention provides a capacitive semiconductor fingerprint sensor that can acquire a fingerprint image simply by using a change in capacitance generated by a distance difference between a sensing electrode and a finger surface and a valley using the same. It is possible to obtain the fingerprint image through the detection circuit to detect the difference in capacitance generated from the ridge and the ridge.The output range of the sensor is fixed by using an image enhancement scheme called local adaptation. We want to increase the brightness by adjusting to the level.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the technical idea of the present invention. do.

Fingerprint images have various output ranges depending on the moisture content of the finger surface. In this state, if the goal and the floor are distinguished by one global reference, when the finger surface is dry (Dry finger), the output level of the goal and the floor is lowered, so that the floor is not easily distinguished. There is a case. In addition, when the surface of the finger is wet (wet finger), the output level is increased, and the bone is determined as the floor. Therefore, the valley and the floor should be distinguished by the local reference value (Lacal reference) suitable for each case, such as a change in the humidity of the finger.

1 is a graph illustrating the effect of local adaptation according to various finger surface conditions.

FIG. 1 (a) shows the finger surface when the finger surface is normal as well as when the dry and wet cases exist simultaneously.

In the case of a dead skin, that is, an appropriate amount of moisture in the first electrode 12, such as 'N' (Normal finger), the epidermis 12 blocks the electrical signal, so that the capacitor It acts as an electrode. In this case, reference numeral 10 denotes a fixed second electrode of the sensor.

However, when the surface of the finger is dry, such as 'A', the amount of moisture contained in the epidermis 12 is small, so that the epidermis 12 does not block the electrical signal, but only acts as a dielectric material. The dermis (Live skin) 11 serves as an electrode. Therefore, since the distance between the two electrodes of the capacitor is as far as the thickness of the skin 12, the output level signal is lowered.

On the other hand, when the surface of the finger is wet with moisture such as sweat or water, such as 'B' (wet finger), since the moisture acts as an electrode, the output signal of the bone filled with moisture is increased.

If the valley and the floor are distinguished by using one total reference value 14 for the output signal value, when it is dried as shown in FIG. Even if it is a bone area like 'D', it is misjudged to the floor area, so it is impossible to obtain a high quality fingerprint image.

Here, the black part of '18' represents the part recognized as the floor of the fingerprint through the second electrode 10 of the sensor, that is, the plate electrode of the sensor, and the white part of '19' is the valley of the fingerprint. It shows the recognized part.

In order to solve this problem, as shown in (c) of FIG. 1, the average value is calculated from the output value of each unit pixel in the locally selected region to generate the local reference value 16, and this value and the original output signal value 17 and By amplifying the difference between and distinguishing the valley from the valley, it is possible to solve the discrimination error of the valley and the valley that appeared in the case of dry and wet, such as 'E' and 'F' shown in Figure 1 (d). .

FIG. 2 is a circuit diagram illustrating a unit pixel structure of a capacitive fingerprint sensor according to an embodiment of the present invention, which is proposed to enhance a fingerprint image, and FIG. 3 is a timing diagram illustrating the operation of FIG. 2.

Referring to FIG. 2, each unit pixel selects a local window of a switched-capacitor amplifier composed of one amplifier and two switched capacitors to obtain a local average. Is composed of a transistor.

Specifically, the sensing unit 20 for sensing the fingerprint image, the output of the sensing unit 20 and the reference voltage Vref are respectively different inputs, and the sensing unit (eg, through the change of the reference voltage Vref) Switched capacitor-type amplifier 21 for amplifying a change in voltage level corresponding to the stored charge detected by 20) and outputting it through the output terminal Vout, and the row direction and the column by a predetermined number of output terminals Vout. Controls the output terminals of neighboring unit pixels in common to each other in a direction, and obtains a local reference value through an average value including the output of neighboring unit pixels connected to its output, and uses the local reference value to output the value of the output terminal (Vout). It comprises a row and column connection portion 22 to obtain a fingerprint image through a localized image enhancement technique for comparing the.

The sensing unit 20 uses the skin of a finger to be contacted for fingerprint detection as a first electrode and a fixed conductor as a second electrode, thereby detecting a difference in capacitance according to a change in distance between the first electrode and the second electrode. The fingerprint image is sensed through the sensor. In this case, the skin of the finger is used as the first electrode, and the finger capacitor Cf connected to the one input terminal of the amplifier 21 is used as an example. .

The amplifier 21 is connected to the second electrode of the finger capacitor Cf and the negative input terminal, an amplifier Amp having a reference voltage Vref as a positive input, and a first control signal Φ1 for controlling whether or not sensing is performed. A first feedback transistor T1 having a gate input and having one side and the other side connected between the negative input terminal of the amplifier Amp and the first output terminal Out of the amplifier Amp, respectively, to form a feedback loop, A second control signal Φ2 that controls whether the sensed fingerprint image is transmitted to the output terminal Vout as a gate input, and has one side connected to the first output terminal Out and the other side connected to the output terminal Vout. The second feedback transistor T2 and the output terminal Vout are connected in series with the second feedback transistor T2 in series with the negative input terminal of the amplifier Amp, and the first feedback transistor is connected between the negative input terminal and the first output terminal Out. And a feedback capacitor Cfb forming a feedback loop in parallel with T1.

The row and column connection units 22 have a third control signal Φ 3 for controlling whether or not the average value is calculated as a gate input, and is connected between the output terminal Vout and the first node n connected to a neighboring unit pixel. The connected first output transistor T3 and the row window selection signal Φrow in the row direction are used as gate inputs, and one side thereof is respectively connected to the first node n, and the other side thereof is a row. First and second row direction switching transistors T5 and T6 connected to second nodes (not shown) of neighboring unit pixels positioned in the positive and negative directions of the arranged unit pixels, and a local region selection signal in the column direction ( Column window selection signal (Φcol) as the gate input, one side of which is connected to the first node (n), respectively, and the other side of the third node of the neighboring unit pixels located in the positive and negative directions of the column-arranged unit pixels. Connected first and second column switching transistors T7 and T8. Include.

Here, in order to reduce power consumption by the unit pixel operation, the amplifier Amp is controlled on and off by its DC bias controlled by the region region selection signal .phi.row in the row direction, and the second output transistor ( T4 has a fourth control signal Φ4 for output control as a gate input and one side thereof is connected to the output terminal Vout, and the signal of the output terminal Vout is connected to the bus line in response to the fourth control signal Φ4. send.

FIG. 4 is a block diagram illustrating a region in which a region is selected in a pixel array including a plurality of unit pixels of FIG. 2, and selection of a region in order to obtain a region average is illustrated in FIG. 4.

4 illustrates the case of 3 * 3. In the row and column directions for determining the size of the local area, the local area selectors 41 and 42 adjust the input of their shift registers. You can change the size of the area.

Since the amplifier of each unit pixel is controlled by the region region selection signal .phi.row in the row direction, the region region selection signal .phi.row in the row direction should be allocated to each unit sensor. The selection signal .phi.row controls the transistors T40 to T45 connecting the unit sensors 40a to 40d. When the row selection signals of two adjacent unit pixels are turned on at the same time, two selection pixels exist between the two unit pixels. Transistors are turned on at the same time, so the two unit sensors are connected vertically.

Since the local area selection signal .phi col in the column direction does not control the operation of the unit pixels, only one is required between each unit pixel. When the column region selection signal Φcol is turned on, one transistor connecting two adjacent unit pixels is turned on, so the two unit sensors are connected in the horizontal direction.

In this way, the local area is selected, and the output signal comes only from the central unit sensor X of the selected area. After this process is completed, the local area to be selected is shifted by the respective shift registers present in the local area selection units 41 and 42 in the row direction and the column direction, and the previous process is repeated in the same manner.

However, in this case, since the output signal comes from only three unit sensors in the case of 3 * 3, three regional areas must be moved in the row direction to obtain the output of one row. Therefore, as the size of the local area increases, the area area movement increases accordingly, and the number of operations increases in proportion to that of one unit pixel, thereby increasing the detection time and power consumption for obtaining the entire fingerprint image.

Therefore, it is necessary to select an optimal local area for obtaining a sufficiently enhanced fingerprint image under the desired detection time and power consumption conditions.

As described above, the proposed circuit can adjust the degree of enhancement of the fingerprint image by controlling the operation of each unit sensor with the selection signal in the row direction, and the fingerprint enhanced by the selection of the operation step of the circuit to be described below. Not only the image but also a raw fingerprint image may be obtained.

The operation of the proposed circuit is largely composed of five steps. Hereinafter, the operation of each circuit will be described in detail with reference to the circuit of FIG. 2 and the timing diagram of FIG. 3.

One). In the reset step, the amplifier Amp is operated by the region region selection signal Φ row in the row direction, and T1 and T2 are turned on by Φ1 and Φ2 to discharge the initial charge stored in the feedback capacitor Cfb. In addition, by connecting the negative input terminal and the output (Out) of the amplifier (Amp) directly to the amplifier (Amp) to operate as a buffer (Buffer) to obtain the DC bias of the amplifier. At this time, if the voltage of the positive input terminal of the amplifier Amp, which is the reference voltage Vref, is set to VH, the voltage of the positive input terminal and the VH voltage is caused by a virtual short phenomenon between the positive input terminal and the negative input terminal of the amplifier Amp. You have a level.

2). After the switched capacitor type amplifier 21 is initialized, T1 is turned off, T2 is turned on, and the input voltage is lowered to VL. Then, the voltage of the finger capacitor Cf becomes Vl, and the charge Cf (VH-VL) corresponding to the dropped voltage VH-VL is moved to the feedback capacitor Cfb.

Therefore, the charge of Cf (VH-VL) is stored in the feedback capacitor Cfb, and the voltage drop of Vf to Cf (VH-VL) / Cfb is generated at the output terminal Vout. At this time, in the case of a floor having a large finger capacitance, a large amount of charge is moved to cause a large drop in the output voltage, whereas in the case of a valley having a small capacitance, a small amount of charge is moved, so that the output stage ( Vout) causes a slight voltage drop.

Therefore, if the output voltage itself is amplified and detected according to the distribution of valleys and ridges in this step, a raw fingerprint image can be obtained. However, the fingerprint image thus obtained is similar to the conventional fingerprint image that could not expect a uniform quality fingerprint image according to various states of the finger surface, so that the enhanced fingerprint image can be obtained through a few additional steps.

Through this step, the feedback capacitor Cfb of each unit sensor stores different charge amounts according to the distribution of valleys and floors, and also has different output voltages.

3). In this situation, if Φ1, Φ3 turn on T1 and T3, and turn off T2 through Φ2, one side of feedback capacitor Cfb is VL and the other side is all feedback in the area selected by Φrow and Φcol. Connected with capacitors.

At this time, since all capacitors in the local area have different charges, if all capacitors are connected at the same time, the charge amount stored in each capacitor is shared with other capacitors by charge sharing, so that all feedback capacitors in the local area are The same amount of charge is obtained, and the voltage at this time has all the feedback capacitors in the selection area having the same amount of charge, and the voltage at this time is the local average in the selection area.

4). At this time, the discharge of charge occurs in the feedback capacitor in the floor region having a large amount of charge, and the inflow of charge occurs in the feedback capacitor in the valley region having a relatively small amount of charge.

Therefore, the output voltage of the unit pixel in the valley that caused the low output voltage is lowered.

The feedback capacitors in the selected region that have undergone the local averaging step store the same amount of charge, and each output voltage has the same local average value. In this situation, if Φ3 is turned off to disconnect the finger capacitors in the selected area, T1 is turned off, T3 is turned on, and Vref is increased from VL to VH, the finger capacitor will lose the charge lost in the charge transfer stage. Recovered, this charge is supplied by the feedback capacitor.

5). Therefore, the output voltage rises as much as the voltage drop generated in the charge movement stage, and only the amount of charge that has flowed in or out of the local averaging stage remains in the feedback capacitor.

After the charge recovery step, the amount of charge remaining in the feedback capacitor generates different output voltages depending on the valley and floor distribution. The output voltage Vout is connected to the row bus by only one central unit sensor in the local area by turning Φ 4 on, so that the storage and transmission unit 55 located at the end of each row bus as shown in FIG. 5 will be described later. Is sampled, amplified by the amplifier 56, and finally output.

When this process is completed, the same process is repeated until the entire region is moved by one unit sensor in the row and column directions by the shift registers in the row and column directions.

However, as the size of the local area increases, the movement of the local area increases by that amount, and the number of operations of one unit sensor increases in proportion to the size of the local area. Thus, the detection time and power consumption for obtaining the entire fingerprint image increase. Therefore, the local area should be selected according to the detection time and power consumption condition.

In the above-described operation, the voltage drop of Cf (VH-VL) / Cgb is obtained by lowering Vref from VH to VL, but the reverse is ie, Cf (VL-VH) / Cfb by raising from VL to VH. As much as the voltage rise can be obtained, the size of the local area is 3 * 3, but other sizes can be modified.

5 is a block diagram illustrating a capacitive fingerprint sensing device using the unit pixel described above.

Referring to FIG. 5, the fingerprint sensing device of the present invention outputs a pixel array 50 in which a plurality of unit pixels of FIG. 2 are arranged, and an area region selection signal Φ row in a row direction to obtain an area reference value. A row direction region selection unit 52 for determining the number of neighboring unit pixels of the < RTI ID = 0.0 > and < / RTI > A column selector 53 for selecting a row in the column direction region region selector 51, a pixel array 50, and transferring the data to the bus line, and for transmitting and storing the data transmitted through the bus line. A storage and transfer section 55, a column selector 54 for designating a column of the pixel array 50 to sequentially output data temporarily stored in the transfer and storage section 55, and a column selector 54. Amplify the data selected by the storage and transfer section 55 And an output unit 56 for outputting, and a control unit 57 for controlling the timing and operation of the above-described components.

In the column direction region area selector 51 and the row direction region area selector 52, the area reference value Φ col in the column direction and the area area selection signal Φ row in the row direction are respectively controlled to calculate the area reference value. The size of the local area is determined, and the data output from the preset local area is output through a unit pixel located at the center of the local area.

When the data output in the preset local area is completed, the column direction local area selector 51 is composed of a shift register so that one column is moved in the pixel array 50 in the next local area.

When the data output of the local area is completed by moving in the column direction, the row direction local area selector 52 also includes a shift register so that the next local area can be moved in the pixel array 50 respectively. The storage and transmission unit 55 stores a buffer unit (not shown) for buffering the data transferred through the bus line, and stores the buffered data in response to a selection signal of the column selector 54. And a storage unit (not shown) to be delivered to the output unit 56.

Here, the storage unit includes a sample an hold circuit.

The operation of the fingerprint sensing device having the above configuration will be described.

First, the output voltage of each unit pixel generated by the above-described operation is transferred to the column bus lines one by one by the row selection signal of the row selector 53, and the value is passed through the buffer to the sample. It is stored in a capacitor in the hold. This value is sequentially selected by the column selector 54, and then amplified by the integrator type output unit 56 which operates in response to the control signal and is output to Vout.

Capacitive fingerprint sensor can be implemented by using standard CMOS process technology, which has the advantages of simple structure, no additional equipment and special process, and small size, low power and low cost. Fingerprint images appeared and in severe cases it was difficult to obtain more than the required fingerprint image.

However, as in the present invention as described above, a region-adaptive image reinforcement technique is introduced into a fingerprint sensor to divide a region of a pixel array into a specific region and apply an average value corresponding to each region through the region of the fingerprint. The embodiment of the present invention has been found to increase the brightness by clearing the division of the floor.

Although the technical idea of the present invention has been described in detail according to the above preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

As described above, the present invention can improve the brightness of the fingerprint image through a localized image reinforcement technique, it can be expected to ultimately improve the reliability of the authentication based on the fingerprint recognition data.

In addition, the present invention can be produced on the basis of the standard CMOS process technology simple and without the need for an additional device, it can be expected to reduce the production cost of the fingerprint sensor to improve the price competitiveness.

Claims (14)

Sensing means for sensing a fingerprint image; The output of the sensing means and the reference voltage are different inputs, and the switched capacitor type of amplifying a change in the voltage level corresponding to the stored charge sensed by the sensing means through the change of the reference voltage and output through the output terminal Amplification means; And The output terminal and the output terminal of the neighboring unit pixels neighboring in the row direction and the column direction by a predetermined number are controlled to be commonly connected to each other, and the local reference value through an average value including its output and the output of the neighboring unit pixels connected thereto. Row and column direction connecting means for obtaining a fingerprint image through a localized image reinforcement technique that compares values of the output terminal using the local reference value. Unit pixel of the capacitive fingerprint sensor comprising a. The method of claim 1, The sensing means, Sensing the fingerprint image through the difference in capacitance as the distance between the first electrode and the second electrode changes, using the epidermis of the finger to be contacted for fingerprint detection as the first electrode and the fixed conductor as the second electrode. Unit pixel of the capacitive fingerprint sensor, characterized in that. The method of claim 2, The sensing means, The unit pixel of the capacitive fingerprint sensor, characterized in that the skin of the finger as a first electrode, the second electrode includes a finger capacitor connected to one input terminal of the amplifying means. The method of claim 3, wherein The amplification means, An amplifier connected to a second electrode of the finger capacitor and a negative input terminal, the amplifier having the reference voltage as a positive input; A first feedback transistor having a first control signal for controlling sensing as a gate input, and having one side and the other side connected between a negative input terminal of the amplifier and a first output terminal of the amplifier to form a feedback loop; A second feedback transistor having a second control signal for controlling whether a sensed fingerprint image is transmitted to the output terminal as a gate input, and having one side connected to the first output terminal and the other side connected to the output terminal; And A feedback capacitor connected to the negative input terminal of the amplifier in series with the second feedback transistor through the output terminal to form a feedback loop in parallel with the first feedback transistor between the negative input terminal and the first output terminal; Unit pixel of the capacitive fingerprint sensor, characterized in that it comprises a. The method of claim 4, wherein The row and column connection means, A first output transistor connected as a gate input to a third control signal for controlling whether to calculate the average value, and connected between the output terminal and a first node connected to a neighboring unit pixel; A local region selection signal in a row direction is used as a gate input, and one side thereof is connected to the first node, respectively, and the other side thereof is connected to a neighboring unit pixel second node positioned in the positive and negative directions of the unit pixel. First and second row switching transistors; And A local region selection signal in a column direction is used as a gate input, and one side thereof is connected to the first node, respectively, and the other side thereof is connected to a neighboring unit pixel third node positioned in the positive and negative directions of the unit pixels. First and Second Column Switching Transistors Unit pixel of the capacitive fingerprint sensor, characterized in that it comprises a. The method of claim 5, wherein The unit pixel of the capacitive fingerprint sensor according to claim 1, wherein the DC bias of the amplifier is controlled by the region region selection signal in the row direction. The method of claim 5, wherein A fourth control signal for output control as a gate input and one side thereof connected to the output terminal, and further comprising a second output transistor for transmitting a signal of the output terminal to a bus line in response to the fourth control signal; Unit pixel of the capacitive fingerprint sensor, characterized in that. A pixel array in which a plurality of unit pixels according to any one of claims 1 and 7 are arranged; Row direction area area selection means for outputting the row area area selection signal to determine the number of neighboring unit pixels in the row direction to obtain the area reference value; Column-area local area selection means for outputting the column-area area selection signal to determine the number of neighboring unit pixels in the column direction to obtain the area reference value; Row selection means for selecting one row of the pixel array and transferring the data to the bus line; Storage and transmission means for transmitting and storing data transmitted through the busline; Column selection means for designating a column of the pixel array to sequentially output the data temporarily stored in the transfer and storage means; And Output means for amplifying and outputting the data selected by said heat selection means and transmitted from said storage and transfer means; Capacitive fingerprint sensor comprising a. The method of claim 8, Determining the size of the area area for calculating the area reference value by controlling the column area area selection signal in the column direction and the row area area selection signal in the column direction area area selection means and the row direction area area selection means, respectively. Capacitive fingerprint sensor. The method of claim 9, And the data output from the preset local area is output through the unit pixel located at the center of the local area. The method of claim 10, When the output of the data in the predetermined region is completed, the column region region selection means is made of a shift register so that one column is moved in the pixel array in the next region region. Fingerprint sensor. The method of claim 11, When the data output of the local area is completed by moving in the column direction, the row area area selection means comprises a shift register so that the next area area is moved in the pixel array, respectively. Type fingerprint sensor. The method of claim 8, The storage and delivery means, And a buffer unit for buffering the data transferred through the bus line, and a storage unit for storing the buffered data and transferring the data to the output unit in response to a selection signal of the column selection unit. Capacitive fingerprint sensor. The method of claim 13, The storage unit, a capacitive fingerprint sensor, characterized in that it comprises a sample and hold (Sample anf hold) circuit.