CN101727571B - Fingerprint sensing device and touch device with fingerprint sensing - Google Patents

Abstract

The invention relates to a fingerprint sensing device and a related touch device with fingerprint sensing, which are provided with specially designed sensing units and can improve the accuracy of fingerprint sensing. The fingerprint sensing device comprises a plurality of sensing units, a driving circuit and a reading circuit. Each sensing unit comprises a fingerprint electrode and a storage capacitor, the storage capacitor is coupled to the fingerprint electrode, and an induction capacitor formed between the fingerprint electrode and a finger is connected in parallel to the storage capacitor. The driving circuit is coupled to the plurality of sensing units and can provide a charging signal to charge the equivalent capacitance of each sensing unit, wherein the equivalent capacitance of any sensing unit is determined according to whether the sensing unit forms an induction capacitance. The reading circuit is coupled to the plurality of sensing units, and can read the voltage value of the storage capacitor of any sensing unit after the equivalent capacitor of the sensing unit is charged so as to judge whether the fingerprint is detected and whether the detected fingerprint is a ridge or a valley.

Description

Fingerprint sensing device and touch device with fingerprint sensing

technical field

The invention relates to fingerprint detection, especially to a fingerprint detection device and a touch device with fingerprint detection.

Background technique

Fingerprint detection (fingerprint detection) is currently the most widely used biometric technology (biometrics). Since each person's fingerprint is different, it can be used to confirm the true identity of the subject. Fingerprint sensing has many excellent features in identifying an identity, so many products have integrated fingerprint sensing functions, such as notebook computers, mobile phones, and flash drives with fingerprint sensing functions.

To effectively perform the fingerprint sensing function, the design of the fingerprint sensor (or fingerprint sensor) is very important. The sensing area of the traditional fingerprint sensor is strip-shaped. When doing fingerprint sensing, you need to move your finger to scan (sweeping scanning), and then recombine the generated strip-shaped fingerprint images to obtain a complete fingerprint. . However, this sensing method has limitations on the speed of brushing and the force of pressing, and it also needs to face problems such as non-uniform contact and image reconstruction.

A fingerprint sensor capable of full fingerprint sensing usually forms a large-area sensing array with a plurality of sensing units to obtain a complete fingerprint at one time without performing reorganization of fragmented fingerprints. A common type of full fingerprint sensor is a capacitive fingerprint sensor. Its sensing unit can form sensing capacitors of different sizes with different parts of the fingerprint, namely furrows and ridges. The sensing capacitance is used to write and read data, and the read data can be used to determine whether the detected valley or ridge is detected. Therefore, for the capacitive fingerprint sensor, how to use this feature to design its sensing unit to effectively detect fingerprints has become an important issue.

Contents of the invention

In view of this, an object of the present invention is to provide a capacitive fingerprint sensing device, which has a specially designed sensing unit, which can simplify the hardware circuit, and avoid mutual interference between adjacent sensing units and external static electricity. interference to improve the accuracy of fingerprint sensing.

Another object of the present invention is to provide a touch device with fingerprint sensing, which can simultaneously provide functions of fingerprint sensing and touch control.

The invention discloses a fingerprint sensing device, comprising: a plurality of sensing units, each sensing unit includes a fingerprint electrode and a storage capacitor, the storage capacitor is coupled to the fingerprint electrode, and the sensing capacitor formed between the fingerprint electrode and the finger is connected in parallel In the storage capacitor; a drive circuit, coupled to the plurality of sensing units, to provide a charging signal to charge the equivalent capacitance of each sensing unit, wherein the equivalent capacitance of any sensing unit It depends on whether the sensing unit forms a sensing capacitance; and a readout circuit, coupled to the plurality of sensing units, is used to read the sensing unit after the equivalent capacitance of any sensing unit is charged. The voltage value of the storage capacitor of the sensing unit.

The present invention also discloses a touch device with fingerprint sensing, which includes the aforementioned fingerprint sensing device, and wherein the plurality of sensing units are configured as a fingerprint sensing area and a touch area, the fingerprint sensing The sensing unit density of the measuring area is higher than the sensing unit density of the touch area.

The present invention also discloses a fingerprint sensing method, including: providing a plurality of sensing units, each sensing unit includes a fingerprint electrode and a storage capacitor, the storage capacitor is coupled to the fingerprint electrode, and the sensing capacitor formed between the fingerprint electrode and the finger It is connected in parallel to the storage capacitor; a charging signal is provided to charge the equivalent capacitance of each sensing unit, wherein the equivalent capacitance value of any sensing unit is determined according to whether the sensing unit forms an inductive capacitance; And after the equivalent capacitance of any sensing unit is charged, read the voltage value of the storage capacitor of the sensing unit.

The invention has the beneficial effects of simplifying the hardware circuit, avoiding the mutual interference between adjacent sensing units and the interference of external static electricity, so as to improve the accuracy of fingerprint sensing.

Description of drawings

1 is a block diagram of a first preferred embodiment of a capacitive fingerprint sensing device of the present invention;

FIG. 2 is a detailed circuit diagram of the sensing unit of FIG. 1;

3A is a cross-sectional view showing when the sensing unit of FIG. 1 detects a valley;

3B is a cross-sectional view showing when the sensing unit of FIG. 1 detects a ridge;

FIG. 4 is a timing diagram of related signals of the capacitive fingerprint sensing device of FIG. 1;

FIG. 5 shows voltage values read from each sensing unit of FIG. 1;

6 is a block diagram of a second preferred embodiment of the capacitive fingerprint sensing device of the present invention;

7 is a detailed circuit diagram of the sensing unit of FIG. 6;

FIG. 8 is a timing diagram of related signals of the capacitive fingerprint sensing device of FIG. 6;

FIG. 9 is another timing diagram of related signals of the capacitive fingerprint sensing device of FIG. 6;

FIG. 10 shows an example of a touch device with fingerprint sensing of the present invention;

FIG. 11 is a flowchart of a preferred embodiment of the fingerprint sensing method of the present invention.

Explanation of reference signs: 10, 60-fingerprint sensing device; 11, 61-sensing array; 12, 62-drive circuit; 13, 63-reading circuit; 14-switching circuit; 15, 65-selection circuit; 16 , 66-reset circuit; 17, 115, 1151-control line; 18, 116, 1161-data line; 19, 117, 661-reset line; 110, 610-sensing unit; 111-fingerprint electrode; 112- Storage capacitor; 113-select switch; 114-reset switch; 118-ground wire; 119-inductive capacitor; 31-substrate; 32, 34, 35-insulation layer; 33-active layer; The process flow of a preferred embodiment.

Detailed ways

The above and other technical features and advantages of the present invention will be described in more detail below in conjunction with the accompanying drawings.

1 is a block diagram of a first preferred embodiment of the capacitive fingerprint sensing device of the present invention, wherein the fingerprint sensing device 10 includes a sensing array 11, a driving circuit 12, a reading circuit 13, a switch Circuit 14 , a selection circuit 15 and a reset circuit 16 . The sensing array 11 includes a plurality of sensing units 110, which are arranged in a plurality of columns (rows) and a plurality of rows (columns) (horizontal columns, vertical rows, eight columns and six rows in the figure, but the number of columns and rows are different. up to this limit). The selection circuit 15 is coupled to the sensing array 11 by a plurality of control lines 17 , and each control line 17 is coupled to a row of sensing units. The switching circuit 14 is coupled to the sensing array 11 by a plurality of data lines 18 , and each data line 18 is coupled to a row of sensing units. The driving circuit 12 and the reading circuit 13 are respectively coupled to the switching circuit 14, and the switching circuit 14 can decide to switch a plurality of data lines 18 to the driving circuit 12 or the reading circuit 13, so that the driving circuit 12 or the reading circuit 13 can be controlled by the data. Wire 18 is connected to sense array 11 . The reset circuit 16 is coupled to the sensing array 11 by a plurality of reset lines 19 , and each reset line 19 is coupled to a row of sensing units. Please note that each control line 17 can also be designed to be coupled to a row of sensing units of the sensing array 11 , and each data line 18 and reset line 19 is respectively coupled to a column of sensing units.

2 is a detailed circuit diagram of the sensing unit 110, which includes a fingerprint electrode 111, a storage capacitor 112, a selection switch 113, a reset switch 114, a control line 115, a data line 116, a reset line 117 and a ground Line 118. The control line 115 is one of the aforementioned plurality of control lines 17 , the data line 116 is one of the aforementioned plurality of data lines 18 , and the reset line 117 is one of the aforementioned plurality of reset lines 19 . The selection switch 113 is coupled between the data line 116 and the fingerprint electrode 111 , and can receive a control signal from the control line 115 to control whether it is turned on or not. The reset switch 114 is coupled between the fingerprint electrode 111 and the ground line 118 , and can receive a reset signal from the reset line 117 to control whether it is turned on or not. The selection switch 113 and the reset switch 114 can be transistor switches, as shown in FIG. 2 . The storage capacitor 112 is formed between the fingerprint electrode 111 and the ground line 118 . An inductive capacitor 119 can be formed between the fingerprint electrode 111 and the finger. Since the human body can be regarded as a ground terminal, the inductive capacitor 119 can be connected in parallel with the storage capacitor 112 , and its equivalent capacitance is the sum of the two capacitances.

The fingerprint electrodes 111 respectively form inductive capacitances of different sizes with the valleys and ridges in the fingerprint, as shown in FIGS. 3A and 3B . 3A and 3B show a cross-sectional view of the sensing unit 110. From bottom to top, there are a substrate 31, a control line 115 and a ground line 118, an insulating layer 32, an active layer 33, a data line 116, and an insulating layer. The layer 34, the fingerprint electrode 111 and the insulating layer 35, wherein the insulating layer 35 not only serves as the contact surface of the finger to form the sensing capacitor 119, but also has a protective function to prevent the sensing unit 110 from being polluted by the outside. In Fig. 3A, the inductive capacitance 119 formed between the fingerprint electrode 111 and the valley is _Cf , which is formed by connecting capacitors _C1 and _C2 in series, the medium of _C1 is air, the medium of _C2 is the insulating layer 35, and the storage The capacitor 112 is C _s ; in FIG. 3B , the inductive capacitor 119 formed between the fingerprint electrode 111 and the ridge is C _r , and its medium is the insulating layer 35 , so its size is equal to C ₂ , while the storage capacitor 112 is still C _s . Therefore, depending on whether a fingerprint is detected and whether the detected part is a ridge or a valley, the following three situations can be distinguished:

(1) A valley is detected: at this time, the equivalent capacitance C _eq1 =C _s +C _f .

(2) Ridges are detected: at this time, the equivalent capacitance C _eq2 =C _s +C _r .

(3) No fingerprint detected: at this time, the equivalent capacitance C _eq3 =C _s .

Since C _f is composed of C ₁ and C ₂ connected in series, C _f <C ₂ =C _r . therefore:

C _eq2 >C _eq1 >C _eq3 formula (1a)

Through the formula (1a), the sensing unit 110 can distinguish whether a fingerprint is detected and whether the detected part is a ridge or a valley, which will be described in detail later. The sensing unit 110 shown in FIGS. 3A and 3B can be manufactured by thin film transistor (Thin Film Transistor, TFT) processing, metal-oxide-semiconductor field-effect transistor (Metal-Oxide-Semiconductor Field-Effect Transistor, MOSFET) processing, etc., there is no special There are no special restrictions on the materials of the fingerprint electrodes 110 and the insulating layers.

Please note that FIGS. 3A and 3B are only one embodiment, and the layout of the components of the sensing unit 110 is not limited thereto. As long as the layout can realize the circuit of the sensing unit 110 in FIG. 2 , it belongs to the scope of the present invention. For example, in another embodiment, the insulating layer 35 in FIGS. 3A and 3B can be omitted. In this way, the inductive capacitor 119 formed between the fingerprint electrode 111 and the valley in _FIG . C _s ; in FIG. 3B , since the fingerprint electrode 111 is in direct contact with the ridges, the sensing capacitor 119 is not formed, and the storage capacitor 112 does not play a role because both ends are grounded. Therefore, when the sensing unit 110 detects a valley, the equivalent capacitance C _eq1 =C _s +C ₁ ; when it detects a ridge, the equivalent capacitance C _eq2 =0; when no fingerprint is detected , the equivalent capacitance C _eq3 = C _s , that is:

C _eq1 >C _eq3 >C _eq2 formula (1b)

Through formula (1b), the sensing unit 110 can also distinguish whether a fingerprint is detected and whether the detected part is a ridge or a valley.

The operation of the fingerprint sensing device 10 is as follows (please refer to FIG. 1 and FIG. 2 ):

(1) Before performing fingerprint sensing, the reset circuit 16 sends a reset signal to each sensing unit 110 through a plurality of reset lines 19, and turns on the reset switch 114 to make the capacitance in the sensing unit 110 It can be fully discharged, and the potential of the fingerprint electrode 111 is forcibly returned to zero. In this way, in addition to clearing the charges left by the previous sensing, the static electricity existing between the finger surface and the fingerprint electrode 111 can also be eliminated, thereby improving the immunity of the fingerprint electrode 111 to external static electricity.

(2) Next, in a writing interval, the selection circuit 15 sends control signals sequentially from each control line 17 to sequentially select each row of sensing units in the sensing array 11, so that the selected sensing units 110 The selection switch 113 of is kept turned on. On the other hand, the switching circuit 14 switches the plurality of data lines 18 to the driving circuit 12 during the writing period, so that the driving circuit 12 can send charging signals through the plurality of data lines 18 . In this way, the selected sensing unit 110 can receive the charging signal through the data line 18 coupled to the selection switch 113 to charge the equivalent capacitance in the sensing unit 110 , that is, write data.

(3) After the writing interval, the selection circuit 15 sends control signals sequentially from each control line 17 again in a read interval, so as to sequentially select each row of sensing units in the sensing array 11, so that the selected The selection switch 113 of the selected sensing unit 110 is kept turned on. On the other hand, the switching circuit 14 switches a plurality of data lines 18 to the reading circuit 13 during this reading interval, so that the reading circuit 13 can read the selected sensor data line 18 coupled with the selection switch 113. The voltage value of the storage capacitor 112 of the unit 110 (in FIG. 2 , that is, the voltage value of the fingerprint electrode 111 ).

Since each sensing unit 110 has a selection switch 113, only when the selection switch 113 is turned on, that is, when the sensing unit 110 is selected, can it read and write data, so that the adjacent sensing units can be avoided. Interference between each other.

FIG. 4 is a timing diagram of related signals of the fingerprint sensing device 10 . Wherein, the time axis (ie, the horizontal axis) is that the writing interval and the reading interval appear repeatedly in sequence. The control signals on each control line 17 (S1, S2, S3... respectively represent the control signals on the 1st, 2nd, 3rd... control lines 17) appear in sequence during the writing period and the reading period , to sequentially select a column of sensing units. In the writing interval, each data line 18 transmits a charge signal (D1, D2... respectively represent the charge signal on the 1st, 2... data line 18) to sense a column selected by the control line 17. The measuring unit is charged, and the length of the charging time of each row of sensing units is the pulse width of the control signal; in the reading interval, each data line 18 transmits the read voltage value of the storage capacitor 112 (V1, V2 ... respectively represent the voltage values on the 1st, 2nd... data lines 18). The reset signal R on each reset line 19 appears at the end of each reading interval to force the voltage value of the fingerprint electrode 111 to zero. Please note that the reset signal R can also appear at the beginning of each writing interval (not shown in the figure), which can achieve the same effect.

During the writing period, since each sensing unit 110 is charged with the same charging signal (such as a fixed voltage value), it can be seen from the quantity (Q)=capacitance (C)×voltage (V), a sensing The charging quantity Q _d of the cell 110 is proportional to the magnitude of its equivalent capacitance. Therefore, in the embodiment where the sensing unit 110 is covered with the insulating layer 35 (see FIGS. 3A and 3B ), it can be deduced from the aforementioned formula (1a):

Q _d (when a ridge is detected)>Q _d (when a trough is detected)>Q _d (when no fingerprint is detected) Formula (2a)

During the reading interval, the read voltage value of the storage capacitor 112 of the sensing unit 110 (that is, the voltage value V _f of the fingerprint electrode 111) is proportional to the charging amount during the previous writing interval, so the formula (2a ) can be derived:

V _f (when ridges are detected)>V _f (when troughs are detected)>V _f (when no fingerprints are detected) Formula (3a)

Therefore, the fingerprint sensing device 10 can judge whether each sensing unit 110 has detected a fingerprint by reading the voltage value of the storage capacitor 112 of each sensing unit 110 and formula (3a), and the detected Whether the fingerprints are ridges or valleys. 5 shows the voltage values read from each sensing unit 110 of the sensing array 11 (taking 11 columns×10 rows as an example), wherein the high voltage value (representing the ridge) is displayed as H, and the middle voltage value (representing Valley) is displayed as M, low voltage value (representing no fingerprint) is displayed as L, and the area surrounded by bold lines is the fingerprint.

Similarly, in the embodiment in which the sensing unit 110 is not covered with the insulating layer 35 (that is, the embodiment in FIGS. 3A and 3B omits the insulating layer 35), the following relationship can be deduced according to the formula (1b):

Q _d (when a valley is detected)>Q _d (when no fingerprint is detected)>Q _d (when a ridge is detected) Formula (2b)

V _f (when a valley is detected)>V _f (when no fingerprint is detected)>V _f (when a ridge is detected) Formula (3b)

By reading the voltage value of the storage capacitor 112 of each sensing unit 110 and formula (3b), it is also possible to determine whether each sensing unit 110 has detected a fingerprint, and whether the detected fingerprint is a ridge or a pattern. valley.

6 is a block diagram of a second preferred embodiment of the capacitive fingerprint sensing device of the present invention, wherein the fingerprint sensing device 60 includes a sensing array 61, a driving circuit 62, a reading circuit 63, a selection circuit 65 and a reset circuit 66 . The sensing array 61 includes a plurality of sensing units 610 arranged in a plurality of columns and rows (six columns and six rows in the figure, but the number of columns and rows is not limited thereto). The selection circuit 65 is coupled to the sensing array 61 by a plurality of first control lines 64 and second control lines 67 , and each first control line 64 and each second control line 67 is respectively coupled to one column of sensing units. The drive circuit 62 is coupled to the sensing array 61 by a plurality of first data lines 68, each first data line 68 is coupled to one row of sensing units, and the read circuit 63 is coupled to the sensor array by a plurality of second data lines 69. Each second data line 69 is coupled to a row of sensing units. The reset circuit 66 is coupled to the sensing array 61 by a plurality of reset lines 661 , and each reset line 661 is coupled to a row of sensing units.

7 is a detailed circuit diagram of the sensing unit 610 . The main difference between the sensing unit 610 and the sensing unit 110 in FIG. The control lines 115 and 1151 are respectively one of the plurality of first control lines 64 and the second control lines 67, and the data lines 116 and 1161 are respectively one of the aforementioned plurality of first data lines 68 and second data lines 69, The reset line 117 is one of the aforementioned plurality of reset lines 661 . The main difference in operation between the sensing unit 610 and the sensing unit 110 is that the sensing unit 610 divides the charging and reading operations into two groups of control lines and data lines (that is, the control line 115 and the data line 116, the control line line 1151 and data line 1161), while the sensing unit 110 is implemented by the same set of control lines and data lines (ie, control line 115 and data line 116). The selection switch 113 can receive a first control signal from the control line 115 to control whether the data line 116 is connected to the fingerprint electrode 111, and the read switch 1131 can receive a second control signal from the control line 1151 to control the connection between the data line 1161 and the fingerprint electrode 111. Whether the fingerprint electrodes 111 are connected. The reset switch 114 can receive a reset signal from the reset line 117 to control whether the fingerprint electrode 111 is connected to the ground line 118 . In addition, the sensing capacitor 119 is still connected in parallel with the storage capacitor 112 , and its equivalent capacitance is the sum of the capacitances of the two.

The operation of the fingerprint sensing device 60 is as follows (please refer to FIG. 6 and FIG. 7 ):

(1) The reset operation before fingerprint sensing, this part is similar to the fingerprint sensing device 10 , please refer to the above, and will not be repeated here.

(2) Next, during the writing interval, the selection circuit 65 sequentially sends out the first control signal from each first control line 64 to sequentially select each row of sensing units in the sensing array 61, so that the selected sensing units The selection switch 113 of the test unit 610 remains turned on. On the other hand, the driving circuit 62 sends charging signals through the plurality of first data lines 68 during the writing period. In this way, the selected sensing unit 610 can receive the charging signal through the first data line 68 coupled to the selection switch 113, and charge the equivalent capacitance in the sensing unit 610, that is, perform data writing. enter.

(3) After the writing period, the selection circuit 65 sequentially sends out the second control signal from each second control line 67 in the reading period, so as to sequentially select each column of sensing units in the sensing array 61, so that the selected The read switch 1131 of the selected sensing unit 610 is kept turned on. On the other hand, the reading circuit 14 reads the voltage value of the storage capacitor 112 of the selected sensing unit 610 through the second data line 69 coupled to the reading switch 1131 during the reading period.

FIG. 8 is a timing diagram of related signals of the fingerprint sensing device 60 . Wherein, the time axis (ie, the horizontal axis) is that the writing interval and the reading interval appear repeatedly in sequence. The first control signals (S1-1, S1-2, S1-3... on each first control line 64 respectively represent the first control signal on the first control line 64 of the 1st, 2nd, 3rd... signals) appear in sequence in the writing interval to sequentially select a column of sensing units; the second control signals (S2-1, S2-2, S2-3... on each second control line 67 represent the first 1, 2, 3... the second control signals on the second control lines 67 appear sequentially in the reading interval, so as to sequentially select a column of sensing units. In the writing interval, each first data line 68 transmits a charge signal (D1, D2... respectively represent the charge signal on the 1st, 2... first data line 68) to charge the first control line A row of sensing cells selected by 64 is charged; in the reading interval, each second data line 69 transmits the read voltage value of the storage capacitor 112 (V1, V2...represent the first, second. .. the voltage value on the second data line 69). The reset signal R on each reset line 661 appears at the end of each reading interval to force the voltage value of the fingerprint electrode 111 to zero. Please note that the reset signal R can also appear at the beginning of each writing interval (not shown in the figure), which can achieve the same effect.

In the second preferred embodiment, the fingerprint sensing device 60 can also perform data writing and reading in the same interval, as shown in FIG. 9 (the codes of the signals in FIG. 9 are the same as those in FIG. 8 ). Compared with FIG. 8, in FIG. 9, on the time axis, the writing interval and the reading interval are the same interval, and, for the same column sensing unit, the first control signal (used to start data writing) is Occurs earlier than the second control signal (used to initiate data reading).

Please note that in the first and second preferred embodiments, when writing data, the selection circuits 15 and 65 are not limited to selecting only one column of sensing units at a time, but can also simultaneously select multiple columns of sensing units for writing.

The fingerprint sensing devices 10 and 60 in FIGS. 1 and 6 can also be used to perform a touch function, so as to be used as a touch pad. Please refer to Fig. 5, after the fingerprint sensing device 10, 60 reads the voltage value from each sensing unit 110, 610, in addition to judging whether a ridge or a valley is detected, it can also detect the fingerprint A reference point (which can be represented by (x, y) coordinates), such as the center point of the fingerprint area, is set in the area. By comparing the reference points in the fingerprint area at different time points, the position and movement direction of the finger can be judged. In addition, since the sensing arrays 11 and 61 can be implemented in a large-area manner, multiple fingerprints can also be detected simultaneously, thereby having a multi-touch function. However, since the touch function only needs to determine the position of the finger, and does not need to be accurate enough to distinguish the ridges and valleys, the sensing unit density (that is, the number of sensing units per unit area) required for the touch function ) is lower than that required for the fingerprint sensing function. Therefore, the present invention proposes a touch device with fingerprint sensing, which has a plurality of sensing units (which may be the sensing unit 110 or 610), respectively configured as a fingerprint sensing area and a touch area, the fingerprint The sensing unit density of the sensing area is higher than that of the touch area, so that fingerprint sensing and touch functions can be provided simultaneously, and the overall circuit cost can be reduced. FIG. 10 shows an example, and it can be seen that the sensing unit density of the fingerprint sensing area is higher than that of the touch area.

Figure 11 is a flow chart of a preferred embodiment of the fingerprint sensing method of the present invention, which includes the following steps:

Step 1100: Provide a plurality of sensing units configured as a sensing array with a plurality of columns and rows, each sensing unit includes a fingerprint electrode and a storage capacitor, the storage capacitor is coupled to the fingerprint electrode, the An inductive capacitor formed between the fingerprint electrode and the finger is connected in parallel with the storage capacitor.

Step 1101: Execute a reset action to reset the potential of the fingerprint electrodes of each sensing unit to zero.

Step 1102: Sequentially select each column of sensing units in the sensing array within a writing interval.

Step 1103: Provide a charging signal to the selected sensing unit during the writing interval to charge an equivalent capacitance in the sensing unit, wherein the equivalent capacitance value is based on whether the sensing unit has It depends on the formation of inductive capacitance.

Step 1104: Sequentially select each column of sensing units in the sensing array within a reading interval.

Step 1105: Read the voltage value of the storage capacitor of the selected sensing unit in the reading interval.

In step 1100, an insulating layer may also be provided to cover the sensing array as the contact surface of the finger to facilitate the formation of sensing capacitance.

In this preferred embodiment, the read interval is located after the write interval, so as to ensure that each row of sensing units has executed a data write operation before executing read. In another embodiment, the read interval and the write interval are located in the same interval, and for the same row of sensing units, steps 1102 and 1103 are performed earlier than steps 1104 and 1105 to ensure that the row of sensing units A data write operation has been performed before a read is performed.

The above description is only illustrative, rather than restrictive, to the present invention. Those of ordinary skill in the art understand that many modifications and changes can be made without departing from the spirit and scope defined by the following appended claims. Or equivalent, but all will fall within the protection scope of the present invention.

Claims (8)

1. A fingerprint sensing device, characterized in that it comprises: A plurality of sensing units, the plurality of sensing units are configured as a sensing array with a plurality of columns and a plurality of rows, each of the sensing units includes a fingerprint electrode, a first switch coupled to the fingerprint electrode, and a storage capacitor, the storage capacitor is coupled to the fingerprint electrode, and an inductive capacitor formed between the fingerprint electrode and a finger is connected in parallel to the storage capacitor; A drive circuit, coupled to the plurality of sensing units, for providing a charging signal to charge an equivalent capacitance of each sensing unit, wherein, any of the sensing units The equivalent capacitance value is determined according to whether the sensing unit has formed the sensing capacitance; a reading circuit, coupled to the plurality of sensing units, for reading the voltage value of the storage capacitor of the sensing unit after the equivalent capacitance of any of the sensing units is charged; a selection circuit, coupled to the sensing array, for sequentially selecting each column of sensing units in the sensing array in a writing interval and a reading interval, the writing interval is located in the Before the reading period, the selection circuit is coupled to the sensing array via a plurality of control lines, each of the control lines is coupled to a column of sensing units in the sensing array; and A switching circuit, coupled to the driving circuit and the reading circuit, the switching circuit is coupled to the sensing array by a plurality of data lines, and each of the data lines is coupled to the sensing array One row of sensing units in the array; in addition, the first switch of each sensing unit is coupled between one of the plurality of data lines and the fingerprint electrode, and the first switch is controlled from the plurality of data lines. One of the lines receives a control signal to control whether it is turned on; Wherein, the driving circuit provides the charging signal to the selected sensing unit in the writing interval, and the reading circuit reads the storage of the selected sensing unit in the reading interval. The voltage value of the capacitor; Wherein, the switching circuit switches the plurality of data lines to the driving circuit during the writing interval, and switches the plurality of data lines to the reading circuit during the reading interval; Wherein, during the writing period, the first switch of the selected sensing unit is kept turned on, so that the data line coupled to the first switch receives the charging signal; During the interval, the first switch of the selected sensing unit is kept turned on, so that the reading circuit can read from the data line coupled to the first switch. 2. The fingerprint sensing device according to claim 1, wherein each sensing unit further comprises a third switch coupled between the fingerprint electrodes and a grounding line, the fingerprint sensing The measuring device also includes: A reset circuit, coupled to the plurality of sensing units, is used for providing a reset signal to the plurality of sensing units to control whether the third switch of the plurality of sensing units is turned on. 3. The fingerprint sensing device according to claim 2, wherein the third switch of any one of the sensing units is before the driving circuit provides the charging signal to the sensing unit or The reading circuit remains turned on after reading the voltage value of the storage capacitor of the sensing unit. 4. The fingerprint sensing device according to claim 1, wherein when any of the sensing units has the sensing capacitance formed, the equivalent capacitance value of the sensing unit is based on the The value of the storage capacitor is determined by the sum of the value of the sensing capacitor. 5. A touch device with fingerprint sensor, characterized in that it comprises: A plurality of sensing units, the plurality of sensing units are configured as a sensing array with a plurality of columns and a plurality of rows, each of the sensing units includes a fingerprint electrode, a first switch coupled to the fingerprint electrode, and a storage capacitor, the storage capacitor is coupled to the fingerprint electrode, and an inductive capacitor formed between the fingerprint electrode and a finger is connected in parallel to the storage capacitor; A drive circuit, coupled to the plurality of sensing units, for providing a charging signal to charge an equivalent capacitance of each sensing unit, wherein the equivalent capacitance of any one of the sensing units The capacitance value is determined according to whether the sensing unit has formed the sensing capacitance; a reading circuit, coupled to the plurality of sensing units, for reading the voltage value of the storage capacitor of the sensing unit after the equivalent capacitance of any of the sensing units is charged; a selection circuit, coupled to the sensing array, for sequentially selecting each column of sensing units in the sensing array in a writing interval and a reading interval, the writing interval is located in the Before the reading interval; wherein the selection circuit is coupled to the sensing array by a plurality of control lines, each of the control lines is coupled to a column of sensing units in the sensing array; A switching circuit, coupled to the driving circuit and the reading circuit, the switching circuit is coupled to the sensing array by a plurality of data lines, and each of the data lines is coupled to the sensing array One row of sensing units in the array; in addition, the first switch of each sensing unit is coupled between one of the plurality of data lines and the fingerprint electrode, and the first switch is connected from the plurality of control lines One of them receives a control signal to control whether to conduct; Wherein, the driving circuit provides the charging signal to the selected sensing unit during the writing interval, and the reading circuit reads the storage of the selected sensing unit during the reading interval. The voltage value of the capacitor; Wherein, the switching circuit switches the plurality of data lines to the driving circuit during the writing interval, and switches the plurality of data lines to the reading circuit during the reading interval; Wherein, during the writing period, the first switch of the selected sensing unit is kept turned on, so that the data line coupled to the first switch receives the charging signal; During the interval, the first switch of the selected sensing unit is kept turned on, so that the reading circuit is read by the data line coupled to the first switch; Wherein, the plurality of sensing units are configured as a fingerprint sensing area and a touch area, and the sensing unit density of the fingerprint sensing area is higher than the sensing unit density of the touch area. 6. The touch device with fingerprint sensing according to claim 5, wherein each sensing unit further comprises a third switch coupled between the fingerprint electrode and a grounding line, The touch device further includes: A reset circuit, coupled to the plurality of sensing units, is used to provide a reset signal to the plurality of sensing units to control whether the third switch of the plurality of sensing units is turned on. 7. The touch device with fingerprint sensing according to claim 6, wherein the third switch of any one of the sensing units provides the charging signal to the sensing unit in the driving circuit. before the detection unit or after the reading circuit reads the voltage value of the storage capacitor of the sensing unit and remains turned on. 8. The touch device with fingerprint sensing according to claim 5, wherein when any one of the sensing units forms the sensing capacitance, the equivalent capacitance value of the sensing unit It is determined according to the sum of the storage capacitor value and the sensing capacitor value.

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