CN117351524A

CN117351524A - Driving module, packaging chip, fingerprint identification device, module and electronic equipment

Info

Publication number: CN117351524A
Application number: CN202311221187.3A
Authority: CN
Inventors: 王鹏鹏; 王海生; 刘英明; 刘晓龙; 黄爱松
Original assignee: TIANJIN JIHAO TECHNOLOGY CO LTD
Current assignee: TIANJIN JIHAO TECHNOLOGY CO LTD
Priority date: 2023-09-20
Filing date: 2023-09-20
Publication date: 2024-01-05

Abstract

The application relates to the technical field of fingerprint identification and provides a driving module, a packaging chip, a fingerprint identification device, a module and electronic equipment. The driving module is used for driving the fingerprint sensor, a first output end of the driving module is used for being connected with an electrode plate of a pixel in the fingerprint sensor, a second output end of the driving module is used for being connected with a grounding end of the fingerprint sensor, the driving module is used for generating a first driving signal and outputting the first driving signal through a first output end of the driving module, so that the pixel generates a fingerprint signal, and is used for generating a first ground signal and outputting the first ground signal to the grounding end of the fingerprint sensor through a second output end of the driving module, so that the grounding voltage of the fingerprint sensor is provided, and the first ground signal is a non-0 level signal relative to the ground. The driving module can improve the acquisition precision of fingerprint signals, thereby improving the accuracy of fingerprint identification and having lower implementation cost.

Description

Driving module, packaging chip, fingerprint identification device, module and electronic equipment

Technical Field

The invention relates to the technical field of fingerprint identification, in particular to a driving module, a packaging chip, a fingerprint identification device, a module and electronic equipment.

Background

In recent years, fingerprint recognition technology is increasingly used in daily life, and fingerprint devices are installed in many devices (such as mobile phones, tablet computers and notebook computers) to recognize the identity of users. The capacitive fingerprint device collects fingerprint signals based on the capacitance of the electrode plate and the surface of the finger, but the accuracy of the collected fingerprint signals is not high, so that the accuracy of fingerprint identification is reduced.

Disclosure of Invention

An objective of the present embodiment is to provide a driving module, a packaged chip, a fingerprint identification device, a module and an electronic device, so as to improve the above technical problems.

In order to achieve the above purpose, the present application provides the following technical solutions:

in a first aspect, an embodiment of the present application provides a driving module, configured to drive a fingerprint sensor, where the fingerprint sensor includes a pixel, a first output end of the driving module is configured to be connected to an electrode plate of the pixel, and a second output end of the driving module is configured to be connected to a ground end of the fingerprint sensor; the driving module is used for generating a first driving signal and outputting the first driving signal through a first output end of the driving module; the first ground signal is generated and is output to the fingerprint sensor through a second output end of the first ground signal so as to provide a ground voltage of the fingerprint sensor; wherein the first ground signal is a non-0 level signal with respect to ground; the fingerprint sensor is used for applying a second driving signal to the electrode plates of the pixels so as to generate fingerprint signals; the second driving signal is the first driving signal or is obtained by conversion according to the first driving signal.

In the above driving module, the ground voltage of the fingerprint sensor is provided by a first ground signal including a non-0 level signal with respect to the ground. When the fingerprint identification is carried out, the finger can be approximately considered to be connected with the ground, so that if the first ground signal is taken as the reference ground, the finger is equivalently driven by applying a signal with the opposite phase to the first ground signal, and the stray capacitance formed by the finger is less because the finger is relatively far away from the metal in the fingerprint sensor, so that the noise in the part of the fingerprint signal generated by the mode of driving the finger is less, the precision of the fingerprint signal is favorably improved, and the accuracy of the fingerprint identification is improved. In addition, the scheme for driving the finger is realized in a signal equivalent mode, and no additional hardware structure is arranged for contacting the finger, so that the implementation cost is lower, and the practical value is higher.

Note that depending on the implementation, the fingerprint signal is not necessarily generated entirely by driving the finger, but may also be generated by driving the electrode plates of the pixels in the fingerprint sensor (using the second driving signal).

In one implementation of the first aspect, the first ground signal includes a square wave signal or a sine wave signal.

In the above implementation manner, the first ground signal may be implemented using a square wave signal or a sine wave signal, so that it is easy to generate the first ground signal.

In an implementation manner of the first aspect, a third output end of the driving module is connected with a power end of the fingerprint sensor; the driving module is also used for generating a first power supply signal and outputting the first power supply signal to the fingerprint sensor through a third output end of the driving module so as to provide the power supply voltage of the fingerprint sensor; the voltage of the first power supply signal is constantly larger than that of the first ground signal, and the voltage difference between the first power supply signal and the first ground signal is constant.

In the above implementation manner, the first power signal may be regarded as a signal obtained by adding a constant first voltage to the first ground signal, so that when the first ground signal is taken as a reference, the first power signal is equivalent to a constant voltage signal, and the voltage of the constant voltage signal maintains the first voltage, so that stable power supply of the fingerprint sensor can be realized when the first ground signal is a non-0 level signal.

In an implementation manner of the first aspect, the second driving signal is the same signal as the first ground signal; or the second driving signal is a signal obtained by increasing the voltage amplitude of the first ground signal by a constant second voltage.

In the above implementation manner, if the second driving signal is the same signal as the first ground signal, when the first ground signal is taken as the reference ground, the second driving signal is equivalent to a 0-level signal, that is, no driving is applied to the electrode plate of the pixel in the fingerprint sensor at this time, and the fingerprint signal is generated by driving the finger completely, so that the formed stray capacitance is less, and the signal-to-noise ratio of the fingerprint signal is higher.

If the second driving signal is a signal obtained by increasing the voltage amplitude of the first ground signal by the second voltage, when the first ground signal is taken as the reference ground, the second driving signal is equivalent to a signal which changes the voltage amplitude of the first ground signal into the second voltage, the driving signal with relatively larger amplitude (compared with the 0-level signal in the previous mode) is applied to the electrode plate of the pixel in the fingerprint sensor, and the equivalent driving signal applied to the finger is equivalent to that two excitation sources simultaneously drive the pixel, so that the driving capability is stronger, and the signal-to-noise ratio of the fingerprint signal can be improved.

In an implementation manner of the first aspect, the driving module is further configured to generate a first power signal to provide a power voltage of the fingerprint sensor, where the voltage of the first power signal is constantly greater than the first ground signal, and a voltage difference with the first ground signal is a constant first voltage, and the second voltage is equal to the first voltage.

In the above implementation, since the second voltage is equal to the first voltage, the amplitude of the second driving signal and the maximum voltage value of the first power supply signal are the same, so that in theory, the second driving signal may be generated using the first driving signal and the first power supply signal, and no additional power supply is required, that is, the signal-to-noise ratio of the fingerprint signal may be improved without increasing the implementation cost.

In an implementation manner of the first aspect, a first output terminal of the fingerprint sensor is connected to a first input terminal of the driving module; the fingerprint sensor is used for generating a control signal and outputting the control signal to the driving module through a first output end of the fingerprint sensor; the driving module is used for responding to the control signal to generate the first ground signal and the first driving signal.

In the above implementation manner, since the first ground signal and the first driving signal are finally used by the fingerprint sensor, the fingerprint sensor can control the driving module to generate the first ground signal and the first driving signal, so that the timing control of the signals is facilitated.

In an implementation manner of the first aspect, a driving signal conversion unit is disposed in the driving module or the fingerprint sensor, an output end of the driving signal conversion unit is connected to an electrode plate of the pixel, and the driving signal conversion unit is configured to convert the first driving signal into the second driving signal.

In the implementation manner, the driving signal conversion unit is arranged to convert the first driving signal into the second driving signal, so that different driving requirements can be flexibly met. Furthermore, the position of the driving signal converting unit can be flexibly set.

In an implementation manner of the first aspect, the driving signal conversion unit is disposed in the fingerprint sensor, the driving signal conversion unit includes a first switching element and a second switching element, a first end of the first switching element is connected to a power supply end of the fingerprint sensor, a first end of the second switching element is connected to a ground end of the fingerprint sensor, a second end of the first switching element and a second end of the second switching element are connected to each other and to an electrode plate of the pixel, and a third end of the first switching element and/or a third end of the second switching element is connected to a first output end of the driving module; the input signal of the third end of the first switching element is used for controlling the conduction state of the first switching element, and the input signal of the third end of the second switching element is used for controlling the conduction state of the second switching element.

In the above implementation manner, the driving signal conversion unit may include two switching elements respectively connected to the power supply terminal and the ground terminal of the fingerprint sensor, so that the implementation is simple in structure, and the conversion of the driving signal can be completed only by using the first ground signal and/or the first power supply signal, without introducing additional signals.

In one implementation manner of the first aspect, the driving module includes a signal generating unit and a boost unit, a first output end of the boost unit is connected to a power supply end of the signal generating unit, a first output end of the signal generating unit is connected to an electrode plate of the pixel, and a second output end of the signal generating unit is connected to a ground end of the fingerprint sensor; the boosting unit is used for boosting a voltage signal input into the unit to generate a second power supply signal, and outputting the second power supply signal to the signal generating unit through a first output end of the boosting unit so as to provide a power supply voltage of the signal generating unit; the signal generating unit is used for generating a first original driving signal and a first original ground signal; the first driving signal is the first original driving signal or is obtained by converting the first original driving signal, and the first ground signal is the first original ground signal or is obtained by converting the first original ground signal.

In an implementation manner of the first aspect, the driving module is further configured to generate a first power signal to provide a power supply voltage of the fingerprint sensor; the third output end of the signal generating unit is connected with the power end of the fingerprint sensor, and the signal generating unit is also used for generating a first original power signal; the first power supply signal is the first original power supply signal or is obtained by conversion according to the first original power supply signal.

In the two implementations, the booster unit is provided to supply power to the signal generating unit with a higher voltage, so that in theory, the signals output by the signal generating unit can also have a larger amplitude, which is beneficial to improving the driving capability of the signals.

In a second aspect, an embodiment of the present application provides a packaged chip, in which the driving module provided in the first aspect or any implementation manner of the first aspect is packaged.

The packaging chip is provided with the driving module provided in the first aspect or any implementation manner of the first aspect, so that the acquisition precision of fingerprint signals can be improved, the accuracy of fingerprint identification is improved, and the implementation cost of the chip is lower.

In a third aspect, an embodiment of the present application provides a fingerprint identification device, including a driving module and a fingerprint sensor provided in any one implementation manner of the first aspect or the first aspect, where the fingerprint sensor includes a pixel, a first output end of the driving module is connected with an electrode plate of the pixel, and a second output end of the driving module is connected with a ground end of the fingerprint sensor.

The fingerprint identification device comprises the driving module provided by the first aspect or any implementation manner of the first aspect, so that the acquisition precision of fingerprint signals can be improved, the fingerprint identification accuracy is improved, and the implementation cost of the device is lower.

In a fourth aspect, an embodiment of the present application provides a fingerprint module, including the fingerprint identification device provided in the third aspect or any implementation manner of the third aspect.

In a fifth aspect, an embodiment of the present application provides an electronic device, including the fingerprint module provided in the fourth aspect or any implementation manner of the fourth aspect.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments of the present application will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of fingerprint signal acquisition in a comparative embodiment;

fig. 2 is a block diagram of a fingerprint identification apparatus, a fingerprint module, and an electronic device according to an embodiment of the present application;

fig. 3 is a circuit diagram of a pixel in a fingerprint sensor according to an embodiment of the present application;

fig. 4 is another circuit diagram of a pixel in the fingerprint sensor according to the embodiment of the present application;

fig. 5 is a circuit diagram of a fingerprint identification apparatus according to an embodiment of the present application;

FIG. 6 is a timing diagram of signals U0, S22, S23, S25 in FIG. 3;

FIG. 7 is a timing diagram of the SVDD, SGND, SDRV, DRV signal of FIG. 5;

FIG. 8 is another timing diagram of the SVDD, SGND, SDRV, DRV signal of FIG. 5;

fig. 9 is a functional schematic diagram of a power management unit according to an embodiment of the present application;

fig. 10 is a functional schematic diagram of a signal generating unit according to an embodiment of the present disclosure;

fig. 11 is a schematic structural diagram of a fingerprint identification apparatus provided in the embodiment of the present application when packaged as a chip;

fig. 12 is a schematic structural diagram of another fingerprint identification device provided in the embodiment of the present application when packaged as a chip;

fig. 13 is a schematic structural diagram of a fingerprint identification apparatus according to an embodiment of the present application when the fingerprint identification apparatus is packaged as two chips.

Detailed Description

The following describes the technical solutions in the embodiments of the present application in detail with reference to the drawings in the embodiments of the present application. It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.

In the present embodiments, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

In the present embodiments, the terms "first," "second," and the like are used merely to distinguish one entity or operation from another entity or operation, and are not to be construed as indicating or implying any actual such relationship or order between such entities or operations.

In the embodiments herein, the term "connected" generally refers to a circuit connection, where the circuit connection may be a direct connection between two elements or an indirect connection via other circuit elements.

The capacitive fingerprint device collects fingerprint signals based on the capacitance formed by the electrode plate and the finger surface, and fig. 1 is a schematic diagram of fingerprint signal collection in a comparative example. Referring to fig. 1, the fingerprint sensor includes pixels arranged in a rectangular array, and each pixel has a similar structure and operation principle, so that only one pixel is taken as an example in fig. 1, the pixel includes electrode plates M1 and M2, and the electrode plates can be made of conductive materials such as metal. M1 is disposed on a side of the sensing surface of M2 close to the fingerprint sensor, which may be a surface of the fingerprint sensor for contact with a finger, in fig. 1, i.e., M1 is located above M2. One end of the electrode plate M1 is connected with the excitation source U1, the other end of the electrode plate M1 is respectively connected with the charge measurement module and the capacitor C, one end of the electrode plate M2 is connected with the excitation source U2, and the capacitor C and the charge measurement module can also be part of a pixel.

When fingerprint identification is performed, a user places a finger on the sensing surface of the fingerprint sensor, that is, above the electrode plate M1 in fig. 1, at this time, the finger surface can be regarded as an electrode plate, and the electrode plate M1 forms a capacitor. The switch S11 is closed, the switch S12 is opened, a driving signal is applied to the electrode plate M1 by using the excitation source U1, so that charges are accumulated on the electrode plate M1, and then the switch S11 is opened, the switch S12 is closed, and the charges on the electrode plate M1 are transferred to the capacitor C at the rear end. By repeating the above-described closing and opening operations for S11 and S12, it is possible to accumulate electric charges on the electrode plate M1 and transfer the accumulated electric charges to the capacitor C a plurality of times, so that the capacitor C has a large amount of electric charges. Then, the switch S13 is closed, and the charge in the capacitor C is transferred to the charge measurement module for measurement, so as to obtain a signal representing the charge amount, which is called a fingerprint signal. The fingerprint signal measured by each pixel corresponds to a pixel value, so that the fingerprint signal measured by all pixels in the pixel array corresponds to a frame of fingerprint image, and fingerprint identification can be performed by utilizing a fingerprint identification algorithm based on the fingerprint image.

In the fingerprint identification process, the electrode plate M2 mainly plays a role of shielding metal below the M1, and a driving signal which is the same as that of the excitation source U1 can be applied to the M2 by the excitation source U2, so that the voltage difference between the electrode plates M1 and M2 is 0, and a new capacitor cannot be introduced due to the addition of a shielding function. Of course, the absence of the excitation source U2 is also an alternative.

It should be appreciated that the fingerprint identification process in the above-described comparative embodiment is merely an example, and that capacitive fingerprint devices are generally similar in identification principle to this embodiment, but not necessarily identical.

For fingerprint signal acquisition, the capacitance between the finger surface and the electrode plate M1 is required, while the other capacitances are usually stray capacitances, which are not required. The inventor researches that although a part of stray capacitance can be shielded by arranging the electrode plate M2, the effect is limited, for example, the mutual capacitance between the electrode plate M1 of the current pixel and the electrode plate M2 of other pixels, the capacitance between the electrode plate M1 and certain metal lines in the pixels and the like are not shielded, and the stray capacitance can influence the charge for forming fingerprint signals, so that noise components in the fingerprint signals are increased, the signal precision is reduced, and the accuracy of fingerprint identification is reduced.

The drive module, the packaging chip, the fingerprint identification device, the fingerprint module and the electronic equipment provided by the embodiment of the application reduce the generation of stray capacitance in a mode of equivalently driving the finger instead of directly driving the electrode plate, so that the signal-to-noise ratio of fingerprint signals is improved, and the improvement of the accuracy of fingerprint identification is facilitated.

It should be noted that, besides the driving module, the packaging chip, the fingerprint identification device, the fingerprint module and the electronic device provided in the embodiments of the present application, the reasons (stray capacitance) which are analyzed by the inventor and result in lower precision of the fingerprint signal should also be considered as contributions made by the inventor to the scheme of the present application, rather than what already exists in the prior art.

Fig. 2 is a block diagram of a fingerprint recognition device 100, a fingerprint module 10, and an electronic device 1 according to an embodiment of the present application.

Referring to fig. 2, the electronic device 1 is a device having a fingerprint recognition function, and may be, for example, a mobile phone, a tablet computer, a notebook computer, a wearable device, an access control device, an in-vehicle device, a robot, or the like.

The electronic device 1 comprises a fingerprint module 10 and can also comprise a processor 20, wherein the fingerprint module 10 is connected with the processor 20, and the fingerprint module 10 and the processor can perform data interaction. The fingerprint module 10 is used for collecting fingerprint images and outputting the fingerprint images to the processor 20, and the processor 20 can perform fingerprint identification based on the fingerprint images on one hand and issue control instructions to the fingerprint module 10 to control the operation of the fingerprint module 10 on the other hand. Of course, if the electronic device 1 also has functions other than fingerprint recognition, the processor 20 may also be used to implement functions other than the above two. It should be appreciated that the electronic device 1 may also contain other components than the fingerprint module 10 and the processor 20, such as a memory, a display screen, a communication module, etc.

In the electronic device 1, the fingerprint module 10 may be disposed at a front, a side, a back, etc. of the device, and the processor 20 may be disposed inside the device. Note that taking the example where the fingerprint module 10 is disposed on the side of the device, it is strictly speaking that the sensing surface of the fingerprint sensor 102 in the module is located on the side of the device, and the whole module may be disposed inside the device.

In this application, the fingerprint module 10 refers to a capacitive module, which collects fingerprint images based on capacitance formed by electrode plates and finger surfaces, and the specific structure of the fingerprint module 10 will be described later.

The processor 20 may be implemented as an integrated circuit chip having signal processing capabilities, which may be a general-purpose processor including a central processing unit (Central Processing Unit, CPU), micro-control unit (Micro Controller Unit, MCU) or other conventional processor, or a special-purpose processor including a digital signal processor (Digital Signal Processor, DSP), application specific integrated circuit (Application Specific Integrated Circuits, ASIC), field programmable gate array (Field Programmable Gate Array, FPGA) or other programmable logic device, discrete gate or transistor logic device, discrete hardware components.

With continued reference to fig. 2, the fingerprint module 10 includes a fingerprint recognition device 100, and the fingerprint recognition device 100 is configured to collect fingerprint signals (meaning will be described later), which may be used to form a fingerprint image that is output to the processor 20, or possibly the fingerprint recognition device 100 already outputs a fingerprint image. Optionally, the fingerprint module 10 further comprises peripheral circuitry associated with the fingerprint recognition device 100, such as connectors or the like for interconnecting the fingerprint recognition device 100 and other parts of the electronic device 1, mechanical fastening structures or the like. Note that the fingerprint recognition device 100 may or may not have a fingerprint recognition function (e.g., the fingerprint recognition function is handed to the processor 20 for completion).

With continued reference to fig. 2, the fingerprint recognition device 100 includes a fingerprint sensor 102 and a driving module 101, where the fingerprint sensor 102 includes a pixel array, the pixel array includes pixels, each pixel includes a first electrode plate, a second electrode plate, and a charge measurement module (also not excluding a case that a plurality of pixels share one charge measurement module), the first electrode plate is disposed on a side of a sensing surface of the second electrode plate, which is close to the fingerprint sensor 102, and one end of the first electrode plate is connected to the charge measurement module. It can be seen that the structure of the pixel here is generally similar to the pixel structure shown in fig. 1, the first electrode plate being electrode plate M1, and the second electrode plate being electrode plate M2.

Each pixel can be used for collecting the corresponding fingerprint signal, and the fingerprint signal collected by each pixel can be regarded as the signal output by the charge measurement module of the pixel, and can be regarded as the signal output by the first electrode plate of the pixel.

The structure that a pixel in the fingerprint sensor 102 may have is described in more detail below by way of two examples:

fig. 3 is a circuit diagram of a pixel in the fingerprint sensor 102 according to an embodiment of the present application. Referring to fig. 3, cf and Cs may be regarded as the capacitance equivalent to the pixel, cf is the capacitance between the finger surface and the electrode plate M1, the upper plate of Cf corresponds to the finger surface, the lower plate of Cf corresponds to M1, cs is the capacitance between the electrode plates M1 and M2, the upper plate of Cs corresponds to M1, and the lower plate of Cs corresponds to M2, or Cs may be regarded as the equivalent of all the capacitances of the pixel except Cf.

U0 is understood to be an excitation source that drives the capacitor Cf, and after excitation by U0, the Cf will accumulate an electric charge therein, as will be further described below with respect to U0.

The operation of the Metal-Oxide-Semiconductor (MOS) transistor switches S21 and S22 is explained later.

When the MOS transistor switch S23 is closed, the charge accumulated on the capacitor Cf is transferred to the capacitor Cc, and the function of S23 is similar to S12 in fig. 1, and the function of the capacitor Cc is similar to the capacitor C in fig. 1.

The portion after the MOS transistor switch S24 may be regarded as a charge measurement module, and the function of S24 is similar to S13 in fig. 1, and the charge in the capacitor Cc is transferred to the charge measurement module for measurement by closing S24.

The charge measurement module in fig. 3 mainly comprises three parts, the first part is an integrator formed by a capacitor C1 and an operational amplifier A1, and the MOS transistor switch S25 can reset the integrator.

The second part is a comparator A2, the non-inverting input end ("+" end) of the comparator A2 is connected with the output end of the integrator, the inverting input end ("-" end) of the comparator A2 is connected with the reference voltage Vref2, if the voltage output by the integrator is larger than Vref2, the comparator A2 outputs a high level, and if the voltage output by the integrator is smaller than Vref2, the comparator A2 outputs a low level. As the integrator continuously accumulates charge, its output voltage is higher or lower, for example, the output voltage of the integrator is initially greater than Vref2, the comparator A2 outputs a high level until the output voltage of the integrator is less than Vref2, and the comparator A2 outputs a low level, i.e., there is a process of inverting the level from the high level to the low level.

The third part is a timing operation unit, which firstly times the time from the start of accumulating charges of the integrator to the voltage inversion of the comparator A2, and then obtains the accumulated charges of the integrator according to the time conversion, namely the charge measurement is completed, and the difference of the charges measured by different pixels can be represented by the difference of fingerprint valleys.

The charge measurement may also be considered as a fingerprint signal collected by the pixels in fig. 3, which may be the pixel values of the pixels in the fingerprint image, or may be converted to obtain the corresponding pixel values of the pixels in the fingerprint image.

Fig. 4 is another circuit diagram of a pixel in the fingerprint sensor 102 according to an embodiment of the present application. Referring to fig. 4, the portions before the charge measurement unit are the same as those of fig. 3, and a description thereof will not be repeated. The charge measurement unit in fig. 4 comprises an integrator, a Buffer and an analog-to-digital converter ADC connected in sequence.

The integrator is the same as that of fig. 3, and the Buffer can realize the impedance transformation function, enhance the load capacity of the output signal of the integrator, and be realized based on the operational amplifier. The ADC is configured to convert the output signal of the Buffer into a digital signal, where the output signal of the Buffer may be a voltage signal, and since the voltage across the capacitor is proportional to the amount of charge of the capacitor, the digital signal may be regarded as a charge measurement result (or may be converted based on the digital signal), that is, a fingerprint signal collected by the pixel in fig. 4, where the fingerprint signal may be a pixel value of the pixel in the fingerprint image, or may be converted to obtain a pixel value of the pixel in the corresponding fingerprint image.

In contrast, the pixel structure of fig. 3 has more accurate measurement of the charge, but has higher requirements on the timing of the element, while the pixel structure of fig. 4 has simpler measurement of the charge and lower requirements on the timing of the element.

It should be appreciated that the structure of the pixels in the fingerprint sensor 102 is not limited to the examples shown in fig. 3 and 4.

With continued reference to fig. 2, the driving module 101 includes a first output terminal, and the first output terminal of the driving module 101 is connected to an electrode plate of a pixel in the fingerprint sensor 102, specifically, at least to the first electrode plate, or may be connected to the second electrode plate. Hereinafter, for simplicity, only a case where the first output terminal of the driving module 101 is connected to both electrode plates of the pixel will be exemplified.

The driving module 101 is configured to generate a first driving signal and output the first driving signal through its first output terminal. After the fingerprint sensor 102 receives the first driving signal, depending on different implementations, the first driving signal may be directly applied to the two electrode plates of the pixel to drive the electrode plates, or the first driving signal may be converted into the second driving signal, and then the second driving signal is applied to the two electrode plates of the pixel to drive the electrode plates, so that the pixel can generate the fingerprint signal, and the specific fingerprint signal generating process is already described above. The second driving signal may be a signal that is more suitable for driving the electrode plate than the first driving signal, and the conversion performed on the first signal may be one or more of signal waveform, phase, amplitude, and the like.

For simplicity, the signals applied to the electrode plates of the pixels may be collectively referred to as a second driving signal, which may be the first driving signal or a signal converted from the first driving signal, according to the above description. Since the second driving signal is applied to both electrode plates of the pixel, the voltage difference between the first electrode plate and the second electrode plate is 0, i.e., no capacitance is introduced between the first electrode plate and the second electrode plate.

There are different ways in which the fingerprint sensor 102 applies the second driving signal to the pixels, for example, the second driving signal may be applied to the pixels in the pixel array row by row, and after each row of pixels collects the fingerprint signal, the second driving signal may be applied to the next row of pixels, which may also be simply referred to as driving the pixels row by row. For another example, the fingerprint sensor 102 may also drive multiple rows of pixels at a time. For another example, the fingerprint sensor 102 may drive all pixels in the pixel array simultaneously, and so on.

Alternatively, the above-mentioned operation of converting the first driving signal into the second driving signal may be performed by some components (not shown in fig. 2) between the driving module 101 and the fingerprint sensor 102, where the fingerprint sensor 102 receives the second driving signal and may directly apply the second driving signal to the two electrode plates of the pixel to drive the electrode plates; alternatively, the driving module 101 may perform the driving, and the fingerprint sensor 102 may receive the second driving signal and directly apply the second driving signal to the two electrode plates of the pixel to drive the electrode plates. In the latter case, the first output of the drive module 101 should be understood as an output (before the drive signal conversion) inside the drive module 101.

Fig. 5 is a circuit diagram of a fingerprint identification apparatus 100 according to an embodiment of the present application. Referring to fig. 5, the circuit in fig. 5 is divided into three parts by a dotted line, the driving module 101 and the fingerprint sensor 102 of the fingerprint recognition device 100 are respectively on the right side, the pixel structure in the fingerprint sensor 102 is similar to that in fig. 1, and the AP end on the left side represents the rest of the electronic apparatus 1 (e.g., the processor 20, etc.). In fig. 5, the first driving signal output from the first output terminal of the driving module 101 is denoted as s_drv, and is converted by the components drv_add, U3, U4 in the fingerprint sensor 102 to obtain the second driving signal SDRV, and is finally applied to the electrode plates M1 and M2. The component drv_add may be configured to superimpose the signal waveform of s_drv with other signal waveforms, and the components U3 and U4 may perform amplitude, phase, etc. conversion on the signal output by drv_add, which will be further described below. It should be noted, however, that the components U3, U4 in fig. 8 mainly function as signal conversion, and the excitation sources U1, U2 in fig. 1 are functionally different.

With continued reference to fig. 2, the driving module 101 further includes a second output terminal, where the second output terminal of the driving module 101 is connected to the ground terminal of the fingerprint sensor 102, and the driving module 101 is further configured to generate a first ground signal, and output the first ground signal to the fingerprint sensor 102 through its second output terminal, so as to provide a ground voltage of the fingerprint sensor 102, that is, a voltage actually existing in a circuit of the fingerprint sensor 102 where the ground is needed. The first ground signal is a signal of a level other than 0 with respect to the ground, that is, a signal of which the voltage is not constant 0. For simplicity, the case where the first ground signal is a square wave signal will be mainly taken as an example hereinafter, and of course, the first ground signal may be another ac signal such as a sine wave signal or a triangular wave signal or a dc signal with a voltage other than 0.

Conventionally, the ground of the fingerprint sensor is typically connected to ground, i.e. the ground inputs a 0 level signal, but in this application the ground of the fingerprint sensor 102 is not directly connected to ground, but to the first ground signal, i.e. belonging to the "floating ground".

With continued reference to fig. 5, the first ground signal output by the second output terminal of the driving module 101 is denoted as SGND, and when fingerprint identification is performed, since the size of the fingerprint sensor 102 is far smaller than that of a human body, a finger of a human body can be approximately considered to be connected to the ground, the ground is referenced to the first ground signal, and the first ground signal is referenced to the first ground signal, which is equivalent to applying a square wave signal with a phase opposite to that of the first ground signal to drive the finger, and since the first ground signal is originally input to the ground terminal of the fingerprint sensor 102, such equivalent is reasonable.

The driving mode has the advantages that: on the one hand, when the finger is regarded as an electrode plate, since the finger is relatively far away from the metal (including the electrode plate, the circuit, etc.) inside the fingerprint sensor 102, the stray capacitance formed is significantly less than that of directly driving the actual electrode plate, so that the noise in the part of fingerprint signals generated by driving the finger is less, which is beneficial to improving the precision of the fingerprint signals, thereby improving the accuracy of fingerprint identification. On the other hand, the finger driving mode is realized by a signal equivalent mode, namely, the signal form of the grounding end of the fingerprint sensor 102 is changed, and no additional hardware structure is arranged to contact and excite the finger, so that the implementation cost is lower and the practical value is higher.

For example, in the pixel circuit of fig. 3 (similar to fig. 4, the ground terminals are all connected with SGND, and SGND is a square wave, and this is equivalent to setting an excitation source U0 connected to a finger (upper plate of capacitor Cf), where U0 outputs a square wave with opposite phase to SGND, and drives the finger. Note that, in fig. 3, the end of the excitation source U0 is connected to the SGND, which only indicates that the output signal of the excitation source U0 is opposite to the SGND, and does not necessarily represent that the excitation source U0 is connected to the ground of the fingerprint sensor 102 in the actual circuit.

Fig. 6 is a timing diagram of the signals U0, S22, S23, S25 in fig. 3. The U0 signal represents the output signal of the equivalent excitation source U0, and the S22, S23, and S25 signals represent the gate signals of the corresponding MOS transistor switches. In connection with fig. 6, the operation of the circuit in fig. 3 is briefly analyzed, and the SGND signal is taken as a reference ground in the analysis:

at the beginning, the S25 signal becomes high level, so that the MOS transistor switch S25 (NMOS) is conducted, and the integrator is reset. The square wave driving signal U0 acts on the upper plate (corresponding to the finger surface) of the capacitor Cf to drive the same, when the upper plate level of the capacitor Cf is pulled high, the S22 signal also becomes high level, so that the MOS transistor switch S22 is turned on, the lower plate level of the capacitor Cf becomes SGND, and the capacitor Cf charges, i.e. accumulates charges, due to the voltage difference between the upper and lower plates of the capacitor Cf. After the signal S22 becomes low level, the MOS switch S22 is turned off, and the capacitor Cf is charged, and at this time, the signal S23 becomes high level, so that the MOS switch S23 is turned on, and the charge accumulated on the capacitor Cf is transferred to the capacitor Cc at the rear end. The signals U0, S22, and S23 are all periodic, which indicates that the above-mentioned capacitor charging and discharging process can be repeated, so that more charges are accumulated in the capacitor Cc to increase the signal amount of the generated fingerprint signal.

In the above analysis, the equivalent driving signal applied to the surface of the finger is focused, but the form of the second driving signal applied to the electrode plate is not limited, and the second driving signal may have various forms, which will be further described later, and for example, it may also include a non-0 level signal with respect to the ground, such as a sine wave signal, a square wave signal, and the like.

With continued reference to fig. 2, the driving module 101 may further include a third output end, where the third output end of the driving module 101 is connected to the power supply end of the fingerprint sensor 102, and the driving module 101 may be further configured to generate a first power signal, and output the first power signal to the fingerprint sensor 102 through its third output end, so as to provide a power supply voltage of the fingerprint sensor 102, that is, a voltage actually existing in a circuit of the fingerprint sensor 102 where the power supply needs to be connected. With continued reference to fig. 5, the first power signal output by the third output terminal of the driving module 101 is denoted as SVDD.

Optionally, the voltage of the first power signal is constantly greater than the voltage of the first ground signal, and the voltage difference with the first ground signal is a constant first voltage. To illustrate the morphology of the first power signal, first, a description mode of the signal morphology is defined:

For a sinusoidal voltage signal (a sinusoidal signal is conveniently expressed as a function, so a sinusoidal signal is taken here as an example, a square wave signal can be similarly analyzed) can be expressed as s=asin (ωt+θ) +k, where a represents the voltage amplitude of s, θ represents the phase of s, k represents the dc voltage component of s, and sin ωt determines the waveform of s, i.e. the sinusoidal wave. I.e. the morphology of the voltage signal can be described in terms of four dimensions of voltage amplitude, phase, dc voltage component and waveform. In particular, if a=0, the expression may also represent a direct current signal.

Given the above definition, the first power supply signal may be considered as a signal obtained by adding the first voltage to the dc voltage component of the first ground signal. If the first voltage is VDD (VDD > 0), the dc voltage component of the first ground signal is 0, and the dc voltage component of the first power signal is VDD, and the waveform, voltage amplitude, and phase of the first power signal are the same as those of the first ground signal. Thus, when the first ground signal is taken as a reference, the first power supply signal is equivalent to a constant voltage signal, and the voltage of the constant voltage signal is always kept at the first voltage VDD, so that stable power supply (actual power supply voltage, that is, VDD) of the fingerprint sensor 102 can be realized in the case that the first ground signal is a signal of a non-0 level.

Note that the first ground signal is introduced above, so that the form of the first power signal may be described relatively simply, but it is not represented that the driving module 101 must generate the first ground signal first and then superimpose the voltage amplitude thereof on VDD to obtain the first power signal, that is, the above description of the form of the first power signal should not be construed as limiting the generation process of the first power signal. For example, the first ground signal and the first power supply signal may be directly generated in synchronization.

In fig. 7 and 8, which will be described later in detail, it can be seen that the first ground signal SGND is a square wave signal having a magnitude of VH (both of fig. 7 and 8 are referenced to the ground), and the first power supply signal SVDD is also a square wave signal having a magnitude of VH, and both are identical in phase (positions of the rising edge and the falling edge are aligned), but the direct-current voltage component of SGND is 0, the direct-current voltage component of SVDD is VDD, so that the maximum voltage value of SGND is VH, and the maximum voltage value of SVDD is vdd+vh.

With continued reference to fig. 5, the driving module 101 may further include a fourth output terminal, where the fourth output terminal of the driving module 101 is connected to a serial peripheral interface (Serial Peripheral Interface, abbreviated as SPI) module of the fingerprint sensor 102. In fig. 5, the AP end, the driving module 101, and the fingerprint sensor 102 are all provided with SPI modules, so that communication can be performed based on the SPI protocol, but since the ground end of the fingerprint sensor 102 is not connected to the ground but is connected to the SGND, the SPI signal used by the fingerprint sensor 102 cannot use the "normal" SPI signal any more, and the SPI signal generated by the driving module 101, that is, the SSPI signal in fig. 5, is used. It should be appreciated that if other protocols are used for communication, the SPI module in FIG. 5 can be replaced with other communication modules.

The structure and the corresponding technical effects of the fingerprint identification device 100 provided in the embodiment of the present application are mainly described above, and the fingerprint module 10 and the electronic device 1 provided in the embodiment of the present application all include the fingerprint identification device 100, so that the fingerprint identification device also has the technical effects of higher accuracy of the collected fingerprint signals, higher accuracy of fingerprint identification, and no obvious increase of implementation cost.

Next, on the basis of the above embodiment, the following describes a possible form of the second driving signal:

fig. 7 is a timing diagram of the SVDD, SGND, SDRV, DRV signal of fig. 5. Referring to fig. 7, the second driving signals SDRV and SGND are identical signals, that is, the waveforms, voltage amplitudes, phases, and dc voltage components of the signals are identical, as already described above with respect to SVDD and SGND.

At this time, when SGND is taken as the reference ground, the SDRV is equivalent to the 0-level signal, that is, the SDRV equivalent signal in fig. 7, and according to the definition of the second driving signal, the SDRV is a signal applied to the electrode plate of the pixel in the fingerprint sensor 102, so that it is equivalent to the case where no driving is applied to the electrode plate of the pixel in the fingerprint sensor 102, that is, the fingerprint signal is generated by driving the finger entirely, so that the formed stray capacitance is small, and the signal-to-noise ratio of the fingerprint signal is high. As for the DRV signal and the S22 signal in fig. 7, the following description will be made.

Fig. 8 is another timing diagram of the SVDD, SGND, SDRV, DRV signal of fig. 5. Referring to fig. 8, regarding SVDD and SGND, which have been described above, the second driving signal SDRV is a signal obtained by increasing the voltage amplitude of SGND by a constant second voltage, and the waveform, phase, and dc voltage component of SDRV are the same as those of SGND. In fig. 8, the second voltage is VDD and the voltage magnitude of SDRV is vdd+vh, which is the same as the first voltage mentioned above, but in the alternative, the second voltage may be different from the first voltage.

Note that the morphology of the SDRV may be described relatively simply by using the morphology of the SGND, but is not meant to represent that the SDRV is actually generated by amplitude transformation on the basis of the SGND, i.e., the above description of the morphology of the SDRV should not be considered as limiting the generation process of the SDRV.

At this time, when SGND is taken as the reference ground, the SDRV is equivalent to a square wave signal that changes the voltage amplitude of SGND to the second voltage, that is, the SDRV equivalent signal in fig. 8, and a driving signal having a relatively large amplitude (compared with the 0 level signal in fig. 7) is applied to the electrode plate of the pixel in the fingerprint sensor 102, and the equivalent driving signal applied to the finger corresponds to that two excitation sources simultaneously drive the pixel, so that the driving capability is relatively strong, and the signal-to-noise ratio of the fingerprint signal can be improved.

Note that in the scheme of fig. 8, the equivalent driving signal applied to the finger generates little stray capacitance, so that it can be considered that the portion of the fingerprint signal corresponding to the driving signal is less noisy; however, the SDRV equivalent signal applied to the electrode plate of the pixel does not generate much stray capacitance, so that it can be considered that the portion of the fingerprint signal corresponding to the driving signal is not much noisy. Thus, the scheme of fig. 8 is not effective in reducing the total amount of stray capacitance as a whole, but, as previously described, the scheme of fig. 8 is equivalent to having two drive signals driving the pixel at the same time, which has a positive effect on the signal-to-noise ratio far exceeding the negative effect of the stray capacitance on the signal-to-noise ratio, and thus still significantly improves the signal-to-noise ratio of the fingerprint signal. As for the DRV signal and the S21 signal in fig. 8, the following description will be made.

It should be understood that the signal configurations in fig. 7 and 8 are merely examples, and that these signals may have configurations different from those in fig. 7 and 8.

In the following, on the basis of the above embodiment, it is further described how the fingerprint sensor 102 converts the first driving signal into a second driving signal (if conversion is required):

Optionally, the fingerprint sensor 102 further includes a driving signal conversion unit, an input end of the driving signal conversion unit corresponds to a first input end of the fingerprint sensor 102, and is connected to a first output end of the driving module 101, and an output end of the driving signal conversion unit is connected to an electrode plate of the pixel. The driving signal conversion unit is configured to receive the first driving signal output by the driving module 101, convert the first driving signal into the second driving signal, and output the second driving signal to the electrode plate of the pixel. The content that can be converted includes one or more of a voltage amplitude, a waveform, a phase, a direct current voltage component, and the like of the first drive signal. The driving signal converting unit may be implemented as a buffer, an inverter, an amplifier, etc., or a combination of devices, and specific examples will be given below.

For example, referring to fig. 5, the previously mentioned components drv_add, U3, U4 may all be considered as part of a drive signal conversion unit for converting the first drive signal s_drv into the second drive signal SDRV. In different implementations, these components may be provided independently for each pixel or may be shared by multiple pixels.

For another example, the driving signal converting unit may include a first switching element having a first end connected to the power supply end of the fingerprint sensor 102 and a second switching element having a first end connected to the ground end of the fingerprint sensor 102, the second end of the first switching element and the second end of the second switching element being connected to each other and to the electrode plate of the pixel, and the third end of the first switching element and/or the third end of the second switching element being connected to the first output end of the driving module 101. The input signal of the third end of the first switching element is used for controlling the conducting state of the first switching element, and the input signal of the third end of the second switching element is used for controlling the conducting state of the second switching element.

Referring to fig. 3, the first switching element may be a MOS transistor switch S21, and the second switching element may be a MOS transistor switch S22. The first end of S21 is the source of S21, which is connected to the power supply end (i.e., SVDD in the figure) of the fingerprint sensor 102, and the first end of S22 is the source of S22, which is connected to the ground end (i.e., SGND in the figure) of the fingerprint sensor 102. The second terminal of S21 and the second terminal of S22 are respective drains, which are connected to each other and to the lower plate of the capacitor Cf, which is the electrode plate M1 of the pixel. The third terminal of S21 and the third terminal of S22 are respectively gates, the gates may control the on state of the MOS transistor switch, and the gates of S21 and/or the gates of S22 are connected to the first output terminal of the driving module 101, for receiving the first driving signal, or a signal obtained by converting the first driving signal (i.e. the first driving signal has been converted before reaching the gates of S21 and/or the gates of S22).

At this time, the input terminal of the driving signal converting unit may consider the gate corresponding to S21 and/or the gate corresponding to S22, specifically which gate depends on which gate is connected to the first output terminal of the driving module 101, and the output terminal may consider the drain corresponding to S21 or the drain of S22 (the two drains are connected to each other). The input terminal of the driving signal converting unit "corresponds to" the gate of S21 and/or the gate of S22, which may be understood that the gate of S21 and/or the gate of S22 directly serve as the input terminal of the driving signal converting unit, or may be understood that the input terminal of another circuit element serves as the input terminal of the driving signal converting unit, however, the output terminal of the circuit element may be connected to the gate of S21 and/or the gate of S22, and the output terminal of the driving signal converting unit "corresponds to" the drain of S21 or the drain of S22, which may be similarly understood.

Taking the case where the gate of S21 and/or the gate of S22 is directly used as the input terminal of the driving signal converting unit, the drain of S21 or the drain of S22 is directly used as the output terminal of the driving signal converting unit as an example, by inputting the first driving signal to the gate of S21 and/or the gate of S22, the on state of S21 and/or S22 can be controlled such that the desired driving signal, that is, the second driving signal, is generated at the drain of S21 or the drain of S22.

The following is a detailed analysis with reference to fig. 7 and 8, respectively. Referring to fig. 7, the "S22 switch" in fig. 7 corresponds to the gate signal of S22 in fig. 3, simply referred to as the S22 signal, and the S22 signal is the first driving signal, and when the S22 signal is at a high level, the MOS transistor switch S22 (NMOS) is turned on, so that SGND is applied to the lower plate of the capacitor Cf, and thus the SDRV signal on the lower plate, that is, the second driving signal, is generated. During this period, the MOS transistor switch S21 may be kept in an off state, and the first output terminal of the driving module 101 may be connected to only the gate of S22, and not to the gate of S21.

Referring to fig. 8, the "S21 switch" in fig. 8 is a gate signal corresponding to S21 in fig. 3, and is simply referred to as an S21 signal, and the S21 signal is a first driving signal, and when the S21 signal is at a low level, the MOS transistor switch S21 (PMOS) is turned on, so that SVDD is applied to the lower plate of the capacitor Cf, and thus the SDRV signal on the lower plate is generated, that is, a second driving signal. During this period, the MOS transistor switch S22 may be kept in an off state, and the first output terminal of the driving module 101 may be connected to only the gate of S21, and not to the gate of S22.

Further, it has been mentioned that SVDD may be a signal obtained by adding a first voltage to a dc voltage component of SGND, and SDRV may be a signal obtained by adding a second voltage to a voltage amplitude of SGND, in fig. 8, the first voltage and the second voltage are the same and are both VDD, so that the amplitudes of SDRV and the maximum voltage value of SVDD are the same and are both vdd+vh, so that in theory, SDRV may be generated using an S21 signal and an SVDD signal, without providing additional power, that is, the scheme of higher signal-to-noise ratio of the finger print signal in fig. 8 can be provided without increasing implementation cost.

The above alternative scheme can convert the first driving signal into the second driving signal according to the driving requirement by arranging the driving signal conversion unit in the fingerprint sensor 102, so that different driving requirements can be flexibly satisfied. Furthermore, the driving signal conversion unit may be implemented as two switching elements (including but not limited to MOS transistor switches) respectively connected to the power supply terminal and the ground terminal of the fingerprint sensor 102, so that the implementation is simple, and the conversion of the driving signal can be completed only by using the first ground signal and/or the first power supply signal, without introducing additional signals, so that the implementation cost is saved.

Alternatively, the driving signal conversion unit may also be disposed in the driving module 101, where the first output end of the driving module 101 is connected to the electrode plate of the pixel in the fingerprint sensor 102 through the driving signal conversion unit, and the driving signal conversion unit is responsible for converting the first driving signal output by the first output end of the driving module 101 into the second driving signal, and then outputting the second driving signal to the fingerprint sensor 102, and finally applying the second driving signal to the electrode plate of the pixel. The specific implementation of the driving signal conversion unit may refer to the case where the driving signal conversion unit is provided in the fingerprint sensor 102, and will not be repeated.

In addition, a scheme of disposing the driving signal conversion unit between the driving module 101 and the fingerprint sensor 102 is not excluded.

The following describes the process of generating a signal by the driving module 101 on the basis of the above embodiment:

alternatively, the fingerprint sensor 102 comprises a first output terminal and the driving module 101 comprises a first input terminal, the first output terminal of the fingerprint sensor 102 being connected to the first input terminal of the driving module 101. The fingerprint sensor 102 is configured to generate a control signal and output the control signal to the driving module 101 through its first output terminal, and the driving module 101 is configured to generate a first ground signal, a first driving signal, and a first power signal (the first power signal is optional) in response to the control signal.

Referring to fig. 1, when fingerprint recognition is required (e.g., when it is detected that a user's finger touches the fingerprint sensor 102), the processor 20 may issue a control instruction to the fingerprint sensor 102, instructing the fingerprint sensor 102 to acquire a fingerprint signal, and the fingerprint sensor 102 may output a control signal to the driving module 101 in response to the control instruction, where the control signal is used to instruct the driving module 101 to generate the first ground signal, the first driving signal, and the first power signal for the fingerprint sensor 102 to acquire the fingerprint signal.

Referring to fig. 5, fig. 5 depicts this process in fig. 1 in more detail. When fingerprint identification is needed, the AP end issues a control instruction to the fingerprint sensor 102 through the SPI module of the AP end, the control instruction firstly reaches the SPI module of the driving module 101, the SPI module of the driving module 101 mainly plays a bridging role, the control instruction is further forwarded to the SPI module of the fingerprint sensor 102, and the SPI module of the fingerprint sensor 102 sends the control instruction to the time sequence control module of the fingerprint sensor 102. On the one hand, the timing control module outputs a DRV signal to the driving module 101, where the DRV signal is the control signal mentioned above, and after the control module receives the DRV signal, the control module generates an SGND signal, an s_drv signal, an SVDD signal, and an SSPI signal, which are output to the fingerprint sensor 102 for use; on the other hand, the timing control module is further configured to perform timing control (e.g., according to the timing in fig. 6) on the pixels and the like in the fingerprint sensor 102, so as to correctly acquire the fingerprint signal.

The DRV signal of fig. 5 is also shown in fig. 7 and 8, and has a waveform that is a square wave pulse for informing the driver module 101 to start generating a corresponding signal.

In the above alternative, since the first ground signal, the first driving signal and the first power signal are all finally provided to the fingerprint sensor 102, the fingerprint sensor 102 can control the driving module 101 to generate the first ground signal, the first driving signal and the first power signal, so that the fingerprint sensor 102 can perform timing control of the signals. In the alternative, the processor 20 may also issue control instructions directly to the driving module 101 to generate the first ground signal, the first driving signal, and the first power signal, as shown by the dashed lines in fig. 1.

Optionally, the driving module 101 includes a signal generating unit and a voltage boosting unit, where a first output end of the voltage boosting unit is connected to a power supply end of the signal generating unit, a first output end of the signal generating unit is connected to an electrode plate of the pixel, a second output end of the signal generating unit is connected to a ground end of the fingerprint sensor 102, and a third output end of the signal generating unit is connected to a power supply end of the fingerprint sensor 102 (the third output end of the signal generating unit is optional), that is, the first output end, the second output end, and the third output end of the signal generating unit respectively correspond to the first output end, the second output end, and the third output end of the driving module 101.

The voltage boosting unit is used for boosting a voltage signal (for example, an analog voltage signal) input into the unit to generate a second power supply signal, and outputting the second power supply signal to the signal generating unit through a first output end of the voltage boosting unit to provide a power supply voltage of the signal generating unit.

The signal generating unit is configured to generate a first original driving signal, a first original ground signal, and a first original power signal (the first original power signal is optional). The first driving signal is a first original driving signal or is obtained by converting according to the first original driving signal, the first ground signal is a first original ground signal or is obtained by converting according to the first original ground signal, and the first power supply signal is a first original power supply signal or is obtained by converting according to the first original power supply signal.

In one implementation, the first input terminal of the signal generating unit is connected to the first output terminal of the fingerprint sensor 102, and the aforementioned driving signal output by the fingerprint sensor 102 through the first output terminal may be input to the signal generating unit, so that the signal generating unit generates the first original driving signal, the first original ground signal, and the first original power signal, and finally outputs the corresponding first driving signal, the first ground signal, and the first power signal from the output terminal of the driving module 101.

Fig. 9 is a functional schematic diagram of a power management unit according to an embodiment of the present application. Referring to fig. 9, the input of the power management unit is an analog voltage AVDD, and the power management unit includes a Low-Dropout linear regulator (LDO) and a Charge Pump (Charge Pump), wherein the LDO is mainly used for implementing a step-down function, that is, converting the AVDD into a signal VDD0 with a lower voltage for outputting, for example, VDD0 may be used for providing Low-voltage power for digital devices, SPI communication modules, etc. in the fingerprint identification apparatus 100; the charge pump is mainly used for realizing the boosting function, that is, converting AVDD into a signal drv_vdd with higher voltage for output, that is, one implementation manner of the boosting unit, drv_vdd is a second power signal, and the output end of the output drv_vdd is the first output end of the charge pump. The LDO and the charge pump may be operated independently.

Fig. 10 is a functional schematic diagram of a signal generating unit according to an embodiment of the present application. Fig. 10 is a functional schematic diagram of a signal generating unit according to an embodiment of the present application. Referring to fig. 10, the left side of the signal generating unit includes three input terminals, from top to bottom (only the sequence in the schematic diagram is not represented in the actual product), the first input terminal is a power terminal, connected to the first input terminal of the charge pump, to which the boosted signal drv_vdd is input, the second input terminal is connected to the fingerprint sensor 102, to which the control signal DRV is input, and the third input terminal is a ground terminal, connected to the ground GND.

The right side of the signal generating unit includes three output terminals, from top to bottom (only in the sequence of the schematic diagram, not representing the sequence in the actual product), where the first output terminal is the third output terminal of the signal generating unit, and is connected to the power terminal of the fingerprint sensor 102, so as to output a first original power signal s_vdd, which may be the first power signal, or may be converted to obtain the first power signal, for example, in fig. 5, the s_vdd may be processed by a Level shifter (Level Shift) to obtain the first power signal SVDD, and output the first power signal to the power terminal of the fingerprint sensor 102. The second output terminal is a first output terminal of the signal generating unit, and is connected to the electrode plate of the pixel, so as to output a first original driving signal s_drv, which may be the first driving signal, or may be converted to obtain the first driving signal, for example, in fig. 5, the first driving signal is the first original driving signal s_drv, and is directly output to the drv_add component of the fingerprint sensor 102. The third output terminal is a second output terminal of the signal generating unit, and is connected to the ground terminal of the fingerprint sensor 102, so as to output a first original ground signal s_gnd, which may be the first ground signal, or may be converted to obtain the first ground signal, for example, in fig. 5, the s_gnd may be processed by a level shifter to obtain the first ground signal SGND, and output the first ground signal SGND to the ground terminal of the fingerprint sensor 102.

Optionally, with continued reference to fig. 5, the signal generating unit may also be configured to generate SSPI signals, the process being similar to the SVDD and SGND signals and not described in detail. In addition, in fig. 5, only the Charge Pump is shown, the LDO is omitted, and the voltage output by the LDO can be used to power the SPI module or the like of the driving module 101.

In the above alternative, the booster unit is provided to supply power to the signal generating unit with a higher voltage, so that in theory, the signals output by the signal generating unit can also have a larger amplitude, which is beneficial to improving the driving capability of the signals. Of course, it is also possible to supply power to the signal generating unit using a normal power supply without providing the booster unit.

Next, on the basis of the above embodiment, the product form that the fingerprint recognition device 100 may have will be described further:

(1) Single package chip morphology

In the configuration (1), the fingerprint recognition device 100 includes a packaged chip in which the driving module 101 and the fingerprint sensor 102 are packaged, which is referred to as a first packaged chip. Form (1) can be subdivided into forms (1.1) and (1.2).

(1.1) a bare chip

The driving module 101 and the fingerprint sensor 102 belong to the same Die (Die) in the first packaged chip.

Fig. 11 is a schematic structural diagram of the fingerprint identification apparatus 100 according to the embodiment of the present application when packaged as a chip. Referring to fig. 11, the first package chip in fig. 11 may be packaged by a Land Grid Array (LGA), the lowest layer is a printed circuit board (Printed Circuit Board, PCB) substrate 106, a Die (gray part) may be fixed on the PCB substrate 106 by Die Bond (Die Bond) to the PCB substrate 106, and a Die Attach Film (DAF or DAF glue) 104 may be filled between the Die and the PCB substrate 106, and the Die includes the circuits of the driving module 101 and the fingerprint sensor 102. The pad (pad) on the Die surface and the pad of the PCB substrate 106 may be connected through a wire bonding process of the metal wire 105, and an epoxy Molding compound (Epoxy Molding Compound, abbreviated as EMC) 103 is encapsulated on the Die surface through a Molding process to form an encapsulated first chip.

Alternatively, the PCB substrate 106 may be replaced by another type of circuit board, such as a flexible circuit board (Flexible Printed Circuit, abbreviated as FPC), a combination of FPC and PCB, a combination of FPC and rigid substrate, or the like.

(1.2) two bare chips

The driving module 101 and the fingerprint sensor 102 belong to two bare chips (each belonging to one bare chip) in the first packaged chip, and the two bare chips are connected through a circuit board in the first packaged chip.

Fig. 12 is a schematic diagram of another structure of the fingerprint identification device 100 according to the embodiment of the present application when packaged as a chip. Referring to fig. 12, fig. 12 includes two Die (gray parts), the left Die includes a circuit of the driving module 101, the right Die includes a circuit of the fingerprint sensor 102, and the two Die are connected through the PCB substrate 106 so as to be communicable with each other. The remainder of fig. 12 is similar to fig. 11 and is not repeated. To reduce signal attenuation, the two Die may be closer together, e.g. no more than 200 μm apart. Alternatively, the PCB substrate 106 may be replaced with other forms of circuit boards.

In the form (1), the driving module 101 and the fingerprint sensor 102 are packaged in the same package chip, so that the implementation mode has higher integration level and better product performance.

(2) Dual package chip morphology

In the configuration (2), the fingerprint recognition device 100 includes two packaged chips, respectively referred to as a second packaged chip and a third packaged chip, which are connected through a circuit board in the device. Wherein the driving module 101 is packaged in a second packaged chip, and the fingerprint sensor 102 is packaged in a third packaged chip.

Fig. 13 is a schematic structural diagram of the fingerprint identification device 100 according to the embodiment of the present application when packaged as two chips. Referring to fig. 13, a third package chip is provided on the left side, and a second package chip is provided on the right side, wherein the third package chip may be an LGA package, the structure may refer to fig. 11, the second package chip has a relatively small volume, and may be an LGA package, a ceramic package, or other manners. An FPC 108 is disposed under the PCB substrate 106, and a second packaged chip may be mounted on the FPC 108 by a surface mount technology (Surface Mounted Technology, abbreviated as SMT). A connector 109 may be further provided at one end (rightmost side in fig. 13) of the FPC 108, and the fingerprint recognition device 100 may be connected to other components. To reduce signal attenuation, the second and third packaged chips may be located closer together, for example no more than 2mm apart. Alternatively, FPC 108 may be replaced with another form of circuit board.

In the form (2), the driving module 101 and the fingerprint sensor 102 are packaged in two different chips, and this implementation is low in cost and flexible to use. For example, in a certain working mode, the second packaging chip on the right side is not required to be started, and only the third packaging chip is used for collecting fingerprint signals, so that the third packaging chip is required to have a function of generating driving signals, and the implementation mode does not have the effect of reducing stray capacitance.

It should be understood that the fingerprint recognition device 100 may have other forms besides (1) (2), and will not be described in detail.

The embodiment of the application also provides a packaged chip, and the driving module provided by the embodiment of the application is packaged in the packaged chip and can be used for driving the fingerprint sensor. For example, the packaged chip may be the second packaged chip described above. The adoption of the packaging chip can improve the acquisition precision of fingerprint signals, thereby improving the accuracy of fingerprint identification and having lower implementation cost.

The foregoing is merely exemplary embodiments of the present application and is not intended to limit the scope of the present application, and various modifications and variations may be suggested to one skilled in the art. Any modification, equivalent replacement, improvement, combination, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. The driving module is characterized by being used for driving a fingerprint sensor, wherein the fingerprint sensor comprises pixels, a first output end of the driving module is used for being connected with electrode plates of the pixels, and a second output end of the driving module is used for being connected with a grounding end of the fingerprint sensor;

the driving module is used for generating a first driving signal and outputting the first driving signal through a first output end of the driving module; the first ground signal is generated and is output to the fingerprint sensor through a second output end of the first ground signal so as to provide a ground voltage of the fingerprint sensor; wherein the first ground signal is a non-0 level signal with respect to ground;

the fingerprint sensor is used for applying a second driving signal to the electrode plates of the pixels so as to generate fingerprint signals; the second driving signal is the first driving signal or is obtained by conversion according to the first driving signal.

2. The drive module of claim 1, wherein the first ground signal comprises a square wave signal or a sine wave signal.

3. The drive module of claim 1, wherein a third output of the drive module is connected to a power supply terminal of the fingerprint sensor;

The driving module is also used for generating a first power supply signal and outputting the first power supply signal to the fingerprint sensor through a third output end of the driving module so as to provide the power supply voltage of the fingerprint sensor;

the voltage of the first power supply signal is constantly larger than that of the first ground signal, and the voltage difference between the first power supply signal and the first ground signal is constant.

4. The drive module of claim 1, wherein the second drive signal is the same signal as the first ground signal;

or the second driving signal is a signal obtained by increasing the voltage amplitude of the first ground signal by a constant second voltage.

5. The drive module of claim 4, further configured to generate a first power signal to provide a power supply voltage of the fingerprint sensor, the first power signal having a voltage constant greater than the first ground signal and a voltage difference from the first ground signal being a constant first voltage, the second voltage being equal to the first voltage.

6. The drive module of claim 1, wherein a first output of the fingerprint sensor is connected to a first input of the drive module;

The fingerprint sensor is used for generating a control signal and outputting the control signal to the driving module through a first output end of the fingerprint sensor;

the driving module is used for responding to the control signal to generate the first ground signal and the first driving signal.

7. The driving module according to claim 1, wherein a driving signal conversion unit is provided in the driving module or the fingerprint sensor, an output end of the driving signal conversion unit is connected to an electrode plate of the pixel, and the driving signal conversion unit is configured to convert the first driving signal into the second driving signal.

8. The driving module according to claim 2, wherein a driving signal conversion unit is provided in the fingerprint sensor, the driving signal conversion unit including a first switching element and a second switching element, a first end of the first switching element being connected to a power supply end of the fingerprint sensor, a first end of the second switching element being connected to a ground end of the fingerprint sensor, a second end of the first switching element and a second end of the second switching element being connected to each other and to an electrode plate of the pixel, a third end of the first switching element and/or a third end of the second switching element being connected to a first output end of the driving module;

The input signal of the third end of the first switching element is used for controlling the conduction state of the first switching element, and the input signal of the third end of the second switching element is used for controlling the conduction state of the second switching element.

9. The driving module according to any one of claims 1 to 8, wherein the driving module comprises a signal generating unit and a boosting unit, a first output terminal of the boosting unit is connected to a power supply terminal of the signal generating unit, a first output terminal of the signal generating unit is connected to an electrode plate of the pixel, and a second output terminal of the signal generating unit is connected to a ground terminal of the fingerprint sensor;

the boosting unit is used for boosting a voltage signal input into the unit to generate a second power supply signal, and outputting the second power supply signal to the signal generating unit through a first output end of the boosting unit so as to provide a power supply voltage of the signal generating unit;

the signal generating unit is used for generating a first original driving signal and a first original ground signal; the first driving signal is the first original driving signal or is obtained by converting the first original driving signal, and the first ground signal is the first original ground signal or is obtained by converting the first original ground signal.

10. The drive module of claim 9, further configured to generate a first power signal to provide a power supply voltage for the fingerprint sensor;

the third output end of the signal generating unit is connected with the power end of the fingerprint sensor, and the signal generating unit is also used for generating a first original power signal; the first power supply signal is the first original power supply signal or is obtained by conversion according to the first original power supply signal.

11. A packaged chip, characterized in that a drive module according to any one of claims 1-10 is packaged inside.

12. A fingerprint recognition device comprising a drive module according to any one of claims 1-10 and a fingerprint sensor, the fingerprint sensor comprising a pixel, a first output of the drive module being connected to an electrode plate of the pixel, a second output of the drive module being connected to a ground terminal of the fingerprint sensor.

13. A fingerprint module comprising the fingerprint recognition device of claim 12.

14. An electronic device comprising the fingerprint module of claim 13.