CN111027516A - Biological characteristic image acquisition device and method and intelligent equipment - Google Patents
Biological characteristic image acquisition device and method and intelligent equipment Download PDFInfo
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- G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- G06V40/00—Recognition of biometric, human-related or animal-related patterns in image or video data
- G06V40/10—Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
- G06V40/12—Fingerprints or palmprints
- G06V40/13—Sensors therefor
- G06V40/1318—Sensors therefor using electro-optical elements or layers, e.g. electroluminescent sensing
Abstract
The embodiment of the application provides a biological characteristic image acquisition device, a biological characteristic image acquisition method and intelligent equipment, and belongs to the technical field of image acquisition. The device includes: a gate switch for outputting a gate signal; the photoelectric sensing unit is connected with the gating switch and used for receiving the gating signal, gating the photoelectric device with the appointed pixel point and converting the biological characteristic optical signal collected by the photoelectric device into an electric charge signal; the charge compensation circuit is used for outputting a compensation signal corresponding to the designated pixel point; and the signal processing circuit is connected with the photoelectric sensing unit and the output end of the charge compensation circuit and used for receiving the charge signal and the compensation signal, superposing the compensation signal on the basis of the charge signal to obtain an effective charge signal, and converting the effective charge signal into a pixel value of a specified pixel point. The technical scheme provided by the embodiment of the application can improve the accuracy of the acquired biological characteristic image and remove the influence of interference signals.
Description
Technical Field
The application relates to the technical field of characteristic information acquisition, in particular to an acquisition device and an acquisition method for a biological characteristic image, intelligent equipment and display equipment.
Background
With the improvement of the demand of people for information security, the biometric identification technology is more and more concerned by various fields. Among the biometric technologies, fingerprint recognition technology has become the most interesting and widely applied technology due to its practical applicability, and especially for handheld mobile devices such as mobile phones and tablet computers, fingerprint recognition has slowly become an indispensable part.
As shown in fig. 1, currently, a finger 104 is placed on a screen 102, a light emitted from a light source 101 is embedded in the screen 102, a part of the light is reflected by the finger, and a fingerprint image collection module 103 collects a reflected light signal and processes the light signal to generate a fingerprint image.
When the built-in light source 101 is a point light source, the image has the characteristics of light at the center and dark at the edge (shown as pattern 22 in a in fig. 2). In the actual fingerprint image collection process, an effective signal (a sine wave 23 shown in B in fig. 2) is superimposed on a low-frequency ground pattern (a triangular wave 21 shown in a in fig. 2), so that the collection of the fingerprint image is interfered, and the accuracy of the fingerprint image is reduced.
Disclosure of Invention
An object of the embodiments of the present application is to provide an apparatus for acquiring a biometric image, so as to improve accuracy of the biometric image.
The embodiment of the application provides a biological characteristic image's collection system, includes:
the gating switch is used for controlling gating signal output;
the photoelectric sensing unit is connected with the gating switch and used for receiving the gating signal, gating the photoelectric device with the appointed pixel point and converting the biological characteristic optical signal collected by the photoelectric device into an electric charge signal;
the charge compensation circuit is used for outputting a compensation signal corresponding to the specified pixel point;
and the signal processing circuit is connected with the photoelectric sensing unit and the output end of the charge compensation circuit and is used for receiving the charge signal and the compensation signal, superposing the compensation signal on the basis of the charge signal to obtain an effective charge signal, and converting the effective charge signal into the pixel value of the specified pixel point.
In one embodiment, the charge compensation circuit includes:
the storage module is used for storing compensation data corresponding to different compensation indexes;
the control module is used for calculating the position relation between the designated pixel point and a reference point to obtain a compensation index; acquiring compensation data corresponding to the compensation index from the storage module, and outputting the compensation data;
and the charge compensation module is connected with the control module and the signal processing circuit and used for receiving the compensation data output by the control module, converting the compensation data into a compensation signal and inputting the compensation signal into the signal processing circuit.
In one embodiment, the charge compensation module comprises:
the digital-to-analog converter is connected with the control module and used for receiving the compensation data output by the control module and converting the compensation data into an analog voltage signal;
and the compensation capacitor is connected with the digital-to-analog converter, and the analog voltage signal converts the analog voltage signal into a compensation signal.
In one embodiment, the charge compensation module further comprises:
the first switch is connected with the digital-to-analog converter and the compensation capacitor, the first switch is closed during charge compensation, and the digital-to-analog converter and the compensation capacitor are conducted; the first switch is turned off at initialization;
and the second switch is connected with the compensation capacitor, the second switch is switched off during charge compensation, the second switch is switched on during initialization, and charges in the compensation capacitor are released from the branch where the second switch is located.
In one embodiment, the signal processing circuit includes:
the charge amplifier is connected with the photoelectric sensing unit and the output end of the charge compensation circuit and used for receiving the charge signal and the compensation signal, superposing the compensation signal on the basis of the charge signal to obtain an effective charge signal, and converting the effective charge signal into an amplified voltage signal;
the voltage amplifier is connected with the output end of the charge amplifier and is used for amplifying the voltage signal;
and the analog-to-digital converter is connected with the output end of the voltage amplifier and is used for converting the amplified voltage signal into the pixel value of the appointed pixel point.
In one embodiment, the voltage amplifier includes:
the nonlinear amplifier is connected with the output end of the charge amplifier and is used for carrying out nonlinear transformation on the amplified voltage signal and compressing the signal range;
and the linear amplifier is connected with the output end of the nonlinear amplifier and the input end of the analog-to-digital converter and used for linearly amplifying the compressed voltage signal and inputting the amplified voltage signal into the analog-to-digital converter.
In one embodiment, the voltage amplifier includes:
the linear amplifier is connected with the output end of the charge amplifier and is used for linearly amplifying the received voltage signal;
and the nonlinear amplifier is connected with the output end of the linear amplifier and the input end of the analog-to-digital converter and used for carrying out nonlinear conversion on the voltage signal subjected to linear amplification and inputting the voltage signal into the analog-to-digital converter after compressing the signal range.
The embodiment of the application also provides a method for acquiring the biological characteristic image, which comprises the following steps:
scanning pixel points in sequence, collecting biological characteristic light signals corresponding to the pixel points, and converting the biological characteristic light signals into charge signals;
determining a compensation signal corresponding to the pixel point according to the position of the pixel point;
superposing the compensation signal on the basis of the charge signal to obtain an effective charge signal;
converting the effective charge signal into a pixel value corresponding to the pixel point;
and obtaining the biological characteristic image based on the pixel value corresponding to each pixel point.
In an embodiment, the determining the compensation signal corresponding to the pixel point according to the position of the pixel point includes:
calculating the position relation between the pixel point and a reference point according to the position of the pixel point to obtain a compensation index;
and acquiring compensation data corresponding to the compensation index, and converting the compensation data into the compensation signal.
In an embodiment, the obtaining of the compensation data corresponding to the compensation index includes:
and calculating compensation data corresponding to the compensation index according to a preset compensation curve.
In an embodiment, calculating a position relationship between the pixel point and a reference point according to the position of the pixel point to obtain a compensation index includes:
calculating the difference value between the abscissa of the pixel point and the abscissa of the reference point to obtain a row difference; calculating the difference value between the vertical coordinate of the pixel point and the vertical coordinate of the reference point to obtain a column difference; wherein the row difference and column difference constitute the compensation index;
the obtaining of the compensation data corresponding to the compensation index includes: and acquiring compensation data corresponding to the compensation index from a preset compensation matrix.
In addition, this application embodiment still provides an intelligent equipment, includes:
a cover plate;
the light source is arranged in the intelligent equipment and used for emitting light rays to irradiate a target object contacting the cover plate;
the collecting device of the biological characteristic image collects the biological characteristic light signal which is emitted by the light source and reflected by the target object.
Further, an embodiment of the present application further provides a display device, including:
a display panel for emitting light to irradiate a target object contacting the display panel;
the collecting device of the biological characteristic image collects the biological characteristic light signal which is sent by the display panel and reflected by the target object.
In one embodiment, the display panel is any one of an OLED panel, an LED panel, and an LCD panel.
According to the technical scheme, the compensation signals corresponding to each pixel point are output through the charge compensation circuit, after the charge signals collected by the photoelectric sensing unit are superposed with the compensation signals, the influence of interference charges is eliminated, the effective charge signals of biological characteristics can be obtained, the effective charge signals are converted into pixel values to be output, the accuracy of collected biological characteristic images can be improved, and the influence of the interference signals is eliminated.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments of the present application will be briefly described below.
FIG. 1 is a schematic diagram of a point light source collection range in the prior art;
FIG. 2 is a schematic diagram of a background art fingerprint image generation;
fig. 3 is a schematic structural diagram of an acquisition apparatus for a biometric image according to an embodiment of the present application;
fig. 4 is a schematic structural diagram of an acquisition apparatus for a biometric image according to an embodiment of the present application;
FIG. 5 is a schematic diagram of a compensation curve provided by an embodiment of the present application;
fig. 6 is a circuit diagram illustrating a connection between a charge compensation module and a signal processing circuit according to an embodiment of the present disclosure;
fig. 7 is a schematic structural diagram of a signal processing circuit according to an embodiment of the present disclosure;
fig. 8 is a schematic structural diagram of a signal processing circuit according to yet another embodiment of the present application;
fig. 9 is a circuit diagram of a non-linear amplifier according to an embodiment of the present application;
fig. 10 is a schematic circuit diagram of a device for acquiring a biometric image according to an embodiment of the present application;
fig. 11 is a schematic flowchart of a method for acquiring a biometric image according to an embodiment of the present application;
fig. 12 is a schematic flowchart of a method for acquiring a biometric image according to another embodiment of the present application on the basis of fig. 11.
Detailed Description
The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.
Like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
Fig. 3 is a schematic structural diagram of an acquisition apparatus 100 for a biometric image according to an embodiment of the present application, where as shown in fig. 3, the acquisition apparatus 100 includes: a gate switch 31, a photo-sensing unit 32, a charge compensation circuit 33, and a signal processing circuit 34.
The gate switch 31 is used to output a gate signal. The strobe signal may include a row strobe signal for indicating a strobed row and a column strobe signal for indicating a strobed column, and the strobed pixel point may be determined based on an intersection of the row and column. In one embodiment, the gating signal output by the gating switch 31 may be a high output to the gated row, a high output to the gated column, and a low output to the other columns and rows.
In an embodiment, the gating switch 31 may be connected to a controller, and the controller may output a pulse signal at preset time intervals, so as to trigger the gating switch 31 to output high levels to a certain row and a certain column in sequence, and to perform gating of the row and the column in sequence.
Wherein, the photoelectric sensing unit 32 is connected with the gate switch 31. The photoelectric sensing unit 32 can receive the gating signal of the gating switch 31, gate the photoelectric device of the designated pixel point, and convert the biological characteristic light signal collected by the photoelectric device into an electric charge signal. The photo-sensing unit 32 may be a CCD (Charge-coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) image sensor. The photo-sensing unit 32 can be regarded as a plurality of photoelectric devices arranged in an array. One pixel point can be considered to correspond to one photoelectric device, and each photoelectric device can be composed of a field effect transistor and a photodiode.
In one embodiment, the gating signal is to output a high level to the x-th row and a high level to the y-th column, i.e. to gate the photoelectric device of the (x, y) pixel. The photoelectric device of the pixel point can convert the collected biological characteristic light signal into an electric charge signal. The biometric characteristic may be a fingerprint or a palm print. The biometric optical signal may be light reflected from the finger or palm surface after the light source is illuminated.
The charge compensation circuit 33 is connected to the output end of the photo-sensing unit 32 and the input end of the signal processing circuit 34, and the charge compensation circuit 33 can output a compensation signal corresponding to a designated pixel point. Under normal conditions, the luminance of the point light source is fixed every time, and the luminance decay curve is also fixed, so the interference signal (i.e. the triangular wave 21 of a in fig. 2) is the same in every collection, and although the effective signal of the fingerprint is different in every collection, because the interference signal is the same in every collection, the interference signal can be removed by calculating the compensation signal of each pixel point, and only the effective signal is left. In one embodiment, the magnitude of the compensation signal for each pixel point may be calculated in advance and stored. In biometric image acquisition, the charge compensation circuit 33 may output a compensation signal based on the stored compensation data.
The signal processing circuit 34 is connected to the output ends of the photoelectric sensing unit 32 and the charge compensation circuit 33, and is configured to receive a charge signal and a compensation signal, superimpose the compensation signal on the basis of the charge signal to obtain an effective charge signal, and convert the effective charge signal into a pixel value of the designated pixel point.
The charge signal can be considered to include both valid and interfering signals. After the supplementary charge is superimposed on the charge signal, it is considered that the influence of the interference signal is eliminated, and only the effective signal is left. The charge signal from which the disturbance is eliminated is referred to as an effective charge signal in the embodiments of the present application. The signal processing circuit 34 can convert the effective charge signal into a pixel value to be output, and finally, the pixel value of each pixel point, that is, the biometric image, can be obtained by gating each pixel point. The pixel value is the gray value of the pixel point and is in the range of 0-255.
Fig. 4 is a schematic structural diagram of an acquisition apparatus 100 for biometric images according to another embodiment of the present disclosure, and as shown in fig. 4, the charge compensation circuit 33 may include: a storage module 331, a control module 332, and a charge compensation module 333.
The storage module 331 is configured to store compensation data corresponding to different compensation indexes. Fig. 5 is a compensation curve, and as shown in fig. 5, the value of each compensation index may correspond to one compensation data (i.e., a compensation parameter on the ordinate).
The control module 332 is configured to calculate a position relationship between the designated pixel point and the reference point to obtain a compensation index, obtain compensation data corresponding to the compensation index from the storage module 331, and further output the compensation data to the charge compensation module 333. The reference point refers to the position (x) of the center of the light source in the acquired image0，y0) Since the point light source position is not changed, the position of the reference point can be considered as a known quantity.
In one embodiment, a pixel point (x, y) is assigned to a reference point (x)0，y0) The positional relationship of (A) may be EuropeThe distance r ═ sqrt ((x-x)0)2+(y-y0)2) And (x, y) represents the position coordinates of the designated pixel point, and the Euclidean distance r can be regarded as a compensation index at the moment. The control module 332 may obtain compensation data corresponding to the distance r from the storage module 331 according to the distance r. The compensation data is the compensation data corresponding to the distance r (compensation index) on the corresponding compensation curve of fig. 5.
In another embodiment, a pixel point (x, y) is assigned to a reference point (x)0，y0) Can be represented by the row and column differences (x ', y'). (x ', y') (x-x)0，y-y0). At this time, (x ', y') may be regarded as a compensation index. The obtaining of the compensation data corresponding to the compensation index may be extracting a value of the (x ', y') position from the compensation matrix, and using the value of the (x ', y') position as the compensation data. The compensation data corresponding to different compensation indexes can be calculated in advance and stored in the storage module 331.
The charge compensation module 333 is connected to the control module 332 and the signal processing circuit 34, and is configured to receive the compensation data output by the control module 332, convert the compensation data into a compensation signal, and input the compensation signal to the signal processing circuit 34.
In one embodiment, as shown in fig. 6, the charge compensation module 333 may include a digital-to-analog converter DAC and a compensation capacitor C. The input end of the digital-to-analog converter is connected to the control module 332 for receiving the compensation data D outputted by the control module 332xy. The DAC converts the compensation data into an analog voltage signal UDAnd outputting the data.
And the output end of the digital-to-analog converter DAC is connected with one end of the compensation capacitor C, and a corresponding compensation signal is obtained by accumulation on the compensation capacitor. The compensation signal Q on the compensation capacitor C is CUD. Wherein, UDRepresenting an analog voltage signal. The other end of the compensation capacitor C is connected to the input terminal of the signal processing circuit 34 and the output terminal of the opto-electric device 321 in the opto-electric sensing unit 32. Thereby inputting the compensation signal to the signal processing circuit 34.
As shown in fig. 6, the signal processing circuit 34 may include a charge amplifier 341, a voltage amplifier 342, and an analog-to-digital converter 343, which are connected in sequence. The charge amplifier 341 may receive the charge signal output by the optoelectronic device 321 and may also receive the compensation signal output by the charge compensation module 333. The charge signal and the compensation signal are added (i.e., effective charge signal) and then input to the inverting input terminal of the charge amplifier 341. The charge amplifier 341 converts the effective charge signal into an amplified voltage signal. The voltage amplifier 342 amplifies the voltage signal, and the analog-to-digital converter 343 converts the amplified voltage signal into a digital signal, that is, a pixel value of a pixel (x, y) corresponding to the photoelectric device 321.
In an embodiment, as shown in fig. 6, the charge compensation module 333 may further include: first switch SxyAnd a second switch N. First switch SxyOne end of the second capacitor is connected with the DAC, and the other end of the second capacitor is connected with the compensation capacitor C. The second switch N may be an N-type fet, in which a gate inputs a reset signal (Rst), a source is connected to the compensation capacitor C, and a drain is connected to a reference voltage.
When Ty inputs high level and the photoelectric device 321 of the appointed pixel point is switched on, the photoelectric device indicates that charge compensation needs to be carried out on the appointed pixel point, and the first switch SxyClosed and the Rst signal is low (i.e. the branch in which the second switch N is located is open). Therefore, the digital-to-analog converter DAC is conducted with the compensation capacitor C, and charges are accumulated on the compensation capacitor C. When Ty inputs low level and the photoelectric device 321 of the designated pixel point is not turned on, initialization is performed. First switch SxyAnd the Rst signal is turned off, and the branch in which the second switch N is located is turned on, so that the charge in the compensation capacitor C is released.
In one embodiment, as shown in fig. 7, the voltage amplifier 342 may include: a non-linear amplifier 3421 and a linear amplifier 3422. An input of the non-linear amplifier 3421 may be connected to an output of the charge amplifier 341. An output of the non-linear amplifier 3421 may be connected to an input of the linear amplifier 3422. The output of the linear amplifier 3422 is connected to the input of the analog-to-digital converter 343.
The charge amplifier 341 is connected to the output ends of the photoelectric sensing unit 32 and the charge compensation circuit 33, and configured to receive the charge signal and a compensation signal, obtain an effective charge signal by superimposing the compensation signal on the basis of the charge signal, and convert the effective charge signal into an amplified voltage signal; the nonlinear amplifier 3421 is connected to the output terminal of the charge amplifier 341 and is used for performing nonlinear transformation on the amplified voltage signal to compress the signal range; a linear amplifier 3422 connected to the output terminal of the non-linear amplifier 3421 for linearly amplifying the compressed voltage signal; the analog-to-digital converter 343 is connected to the output end of the linear amplifier 3422, and is configured to convert the linearly amplified voltage signal into the pixel value of the designated pixel.
In another embodiment, as shown in fig. 8, a non-linear amplifier 3421 may be located between the linear amplifier 3422 and the analog-to-digital converter 343, with an input of the non-linear amplifier 3421 connected to an output of the linear amplifier 3422 and an output of the non-linear amplifier 3421 connected to an input of the analog-to-digital converter 343.
The charge amplifier 341 is connected to the output ends of the photoelectric sensing unit 32 and the charge compensation circuit 33, and configured to receive the charge signal and a compensation signal, superimpose the compensation signal on the basis of the charge signal to obtain an effective charge signal, and convert the effective charge signal into an amplified voltage signal; the linear amplifier 3422 is connected to the output terminal of the charge amplifier 341 and is used for amplifying the voltage signal; the nonlinear amplifier 3421 is connected to the output end of the linear amplifier 3422, and is used for performing nonlinear transformation on the amplified voltage signal and compressing the signal range; the analog-to-digital converter 343 is connected to the output terminal of the non-linear amplifier 3421, and is configured to convert the compressed voltage signal into the pixel value of the designated pixel.
In one embodiment, the linear amplifier 3422 may be a negative feedback amplifier, a differential amplifier based on an operational amplifier. The instrumentation amplifier is an improvement of a differential amplifier, and can also be used as a linear amplifier 3422. The nonlinear amplifier 3421 may be a logarithmic amplifier, an exponential amplifier, and an exponentiation amplification circuit. The structure of the logarithmic amplifier may be as shown in fig. 9, for example. The output voltage and the input voltage satisfy:
wherein, UTAnd ISAre constant only with respect to the process of the transistor T.
The nonlinear amplifier 3421 performs nonlinear transformation on the voltage signal to compress the signal range, so that the acquired signal is more uniform, the dynamic range of the acquisition device 100 is expanded, and the acquisition precision is improved.
In one embodiment, as shown in fig. 10, the gating switch 31 may be a row gating switch 311, which may sequentially output a high level to each row, thereby sequentially gating on a row of electro-optical devices 321. The controller 35 may output a pulse signal to the row strobe switch 311 at a fixed time, and trigger the row strobe switch 311 to output a row strobe signal at a corresponding frequency. The optoelectronic devices 321 in the same row may correspondingly connect a set of the signal processing circuit 34 and the charge compensation circuit 33. The opto-electronic devices 321 of the same column may be connected to the same set of signal processing circuit 34 and charge compensation circuit 33.
For example, T1The signal is a strobe signal of a row 1, P11 is a photodiode of a column 1 and a row 1, when T1 is at a high level, all the photodiodes P11, P12 of the row 1 are gated, a charge signal of the photodiode P11 of the column 1 in the row 1 passes through the signal processing circuit 34, the charge compensation circuit 33 outputs a compensation signal to the signal processing circuit 34 based on a position relation between P11 and a reference point, the signal processing circuit 34 receives the charge signal and the compensation signal, and a pixel value of a pixel point corresponding to P11 is obtained after processing. Similarly, the pixel value of each pixel point can be obtained, and a biological characteristic image (e.g., a fingerprint image) is obtained.
Fig. 11 is a flowchart of a method for acquiring a biometric image according to an embodiment of the present application, which may be performed by the apparatus 100 for acquiring a biometric image described above. As shown in fig. 11, the acquisition method may include the following steps 1110-1150.
In step 1110, scanning pixel points in sequence, collecting biometric optical signals corresponding to the pixel points, and converting the biometric optical signals into charge signals;
in one embodiment, the biometric optical signal may be collected by the photo sensor unit 32 and converted to an electrical charge signal. The photoelectric sensing unit 32 can receive the gating signal to gate the designated pixel, that is, scan the pixel. The photo-sensing unit 32 can receive the row strobe signal and the column strobe signal, thereby strobing the photoelectric device 321 corresponding to the pixel point. By continuously updating the row strobe signal and the column strobe signal, the scanning of all the pixel points can be completed.
The photoelectric device 321 gated by each pixel point can collect a biological characteristic optical signal and convert the biological characteristic optical signal into an electrical signal.
In step 1120, according to the position of the pixel point, a compensation signal corresponding to the pixel point is determined. In one embodiment, the corresponding compensation signal may be determined by the charge compensation circuit 33 according to the position of the pixel point.
In step 1130, the compensation signal is superimposed on the charge signal to obtain an effective charge signal. In one embodiment, the signal processing circuit 34 may be connected at its input terminals to the photo-sensing unit 32 and the charge compensation circuit 33, respectively, to receive the charge signal and the compensation signal. The superposition of the charge signal and the compensation signal can be considered to cancel the interference charge, resulting in an effective charge signal.
In step 1140, the effective charge signal is converted into a pixel value corresponding to the pixel point. In one embodiment, the signal processing circuit 34 may include a charge amplifier 341, a voltage amplifier 342, and an analog-to-digital converter 343, which are connected in sequence. The charge amplifier 341 converts the effective charge signal into an amplified voltage signal. The voltage amplifier 342 linearly amplifies the amplified voltage signal. The analog-to-digital converter 343 converts the linearly amplified voltage signal into a pixel value for output.
In step 1150, a biometric image is obtained based on the pixel value corresponding to each pixel point.
In one embodiment, as shown in fig. 12, the step 1120 may include the following steps 1121, 1122.
In step 1121, the position relationship between the pixel point and the reference point is calculated according to the position of the pixel point, so as to obtain a compensation index.
Wherein the reference point refers to the position of the center of the light source in the image. In one embodiment, the positional relationship of the pixel points to the reference points may be calculated by the control module 332 of the charge compensation circuit 33. Pixel point (x, y) and reference point (x)0，y0) The position relation of (2) can be Euclidean distance, and can also be used for representing row difference of pixel points and a reference point and column difference of the pixel points and the reference point. In one embodiment, the compensation index may be an euclidean distance r ═ sqrt ((x-x)0)2+(y-y0)2). In another embodiment, the compensation index may also be represented by the row and column difference (x ', y'). (x ', y') (x-x)0，y-y0). x 'represents the difference between the abscissa of the pixel and the abscissa of the reference point, and y' represents the difference between the ordinate of the pixel and the ordinate of the reference point.
In step 1122, compensation data corresponding to the compensation index is obtained, and the compensation data is converted into the compensation signal.
In an embodiment, the control module 332 may calculate compensation data corresponding to the compensation index according to a preset compensation curve. In another embodiment, the control module 332 may obtain the value of the position where (x ', y') is located from a preset compensation matrix, that is, the compensation data corresponding to the compensation index.
In an embodiment, the compensation data may be converted into the compensation signal by the charge compensation module 333 in the above embodiment, which may specifically refer to fig. 6 for the corresponding embodiment, and details are not repeated here.
The embodiment of the application also provides intelligent equipment, and the intelligent equipment can be a smart phone, a tablet personal computer, a fingerprint lock or a fingerprint attendance machine and the like.
The intelligent device comprises a cover plate, a light source and the acquisition device 100 of the biological characteristic image provided by the embodiment of the application. The light source is arranged in the intelligent equipment and used for emitting light rays to irradiate a target object contacting the cover plate; the target object may be a finger or a palm, etc. The collecting device 100 collects the biological characteristic light signal emitted by the light source and reflected by the target object, and converts the light signal into a pixel value to obtain a biological characteristic image.
In one embodiment, a display panel may be used as the cover plate and the light source. The smart device may be a Display device, and the Display panel may be any one of an OLED (organic light-Emitting Diode) panel, an LED (light Emitting Diode) panel, and an LCD (Liquid Crystal Display) panel. The display panel can emit light to irradiate a target object contacting the display panel; the device 100 for acquiring a biometric image according to the embodiment of the present application can acquire a biometric optical signal emitted by a display panel and reflected by a target object, and convert the optical signal into a pixel value for output through a series of processes.
In the embodiments provided in the present application, the disclosed apparatus and method can be implemented in other ways. The apparatus embodiments described above are merely illustrative, and for example, the flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods and computer program products according to various embodiments of the present application. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
In addition, functional modules in the embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.
The functions, if implemented in the form of software functional modules and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application or portions thereof that substantially contribute to the prior art may be embodied in the form of a software product stored in a storage medium and including instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
Claims (14)
1. An apparatus for acquiring a biometric image, comprising:
the gating switch is used for controlling gating signal output;
the photoelectric sensing unit is connected with the gating switch and used for receiving the gating signal, gating the photoelectric device with the appointed pixel point and converting the optical signal which is acquired by the photoelectric device and contains the biological characteristics into an electric charge signal;
the charge compensation circuit is used for outputting a compensation signal corresponding to the specified pixel point;
and the signal processing circuit is connected with the photoelectric sensing unit and the output end of the charge compensation circuit and is used for receiving the charge signal and the compensation signal, superposing the compensation signal on the basis of the charge signal to obtain an effective charge signal, and converting the effective charge signal into the pixel value of the specified pixel point.
2. The apparatus of claim 1, wherein the charge compensation circuit comprises:
the storage module is used for storing compensation data corresponding to different compensation indexes;
the control module is used for calculating the position relation between the designated pixel point and a reference point to obtain a compensation index; acquiring compensation data corresponding to the compensation index from the storage module, and outputting the compensation data;
and the charge compensation module is connected with the control module and the signal processing circuit and used for receiving the compensation data output by the control module, converting the compensation data into a compensation signal and inputting the compensation signal into the signal processing circuit.
3. The apparatus of claim 2, wherein the charge compensation module comprises:
the digital-to-analog converter is connected with the control module and used for receiving the compensation data output by the control module and converting the compensation data into an analog voltage signal;
and the compensation capacitor is connected with the digital-to-analog converter, and the analog voltage signal converts the analog voltage signal into a compensation signal.
4. The apparatus of claim 3, wherein the charge compensation module further comprises:
the first switch is connected with the digital-to-analog converter and the compensation capacitor, the first switch is closed during charge compensation, and the digital-to-analog converter and the compensation capacitor are conducted; the first switch is turned off at initialization;
and the second switch is connected with the compensation capacitor, the second switch is switched off during charge compensation, the second switch is switched on during initialization, and charges in the compensation capacitor are released from the branch where the second switch is located.
5. The apparatus of claim 1, wherein the signal processing circuit comprises:
the charge amplifier is connected with the photoelectric sensing unit and the output end of the charge compensation circuit and used for receiving the charge signal and the compensation signal, superposing the compensation signal on the basis of the charge signal to obtain an effective charge signal, and converting the effective charge signal into an amplified voltage signal;
the voltage amplifier is connected with the output end of the charge amplifier and is used for amplifying the voltage signal;
and the analog-to-digital converter is connected with the output end of the voltage amplifier and is used for converting the amplified voltage signal into the pixel value of the appointed pixel point.
6. The apparatus of claim 5, wherein the voltage amplifier comprises:
the nonlinear amplifier is connected with the output end of the charge amplifier and is used for carrying out nonlinear transformation on the amplified voltage signal and compressing the signal range;
and the linear amplifier is connected with the output end of the nonlinear amplifier and the input end of the analog-to-digital converter and used for linearly amplifying the compressed voltage signal and inputting the amplified voltage signal into the analog-to-digital converter.
7. The apparatus of claim 5, wherein the voltage amplifier comprises:
the linear amplifier is connected with the output end of the charge amplifier and is used for linearly amplifying the received voltage signal;
and the nonlinear amplifier is connected with the output end of the linear amplifier and the input end of the analog-to-digital converter and used for carrying out nonlinear conversion on the voltage signal subjected to linear amplification and inputting the voltage signal into the analog-to-digital converter after compressing the signal range.
8. A method for acquiring a biometric image, comprising:
scanning pixel points in sequence, collecting biological characteristic light signals corresponding to the pixel points, and converting the biological characteristic light signals into charge signals;
determining a compensation signal corresponding to the pixel point according to the position of the pixel point;
superposing the compensation signal on the basis of the charge signal to obtain an effective charge signal;
converting the effective charge signal into a pixel value corresponding to the pixel point;
and obtaining the biological characteristic image based on the pixel value corresponding to each pixel point.
9. The method according to claim 8, wherein the determining the compensation signal corresponding to the pixel point according to the position of the pixel point comprises:
calculating the position relation between the pixel point and a reference point according to the position of the pixel point to obtain a compensation index;
and acquiring compensation data corresponding to the compensation index, and converting the compensation data into the compensation signal.
10. The method according to claim 9, wherein the position relationship is an euclidean distance between the pixel point and a reference point, and the obtaining of the compensation data corresponding to the compensation index includes:
and calculating compensation data corresponding to the compensation index according to a preset compensation curve.
11. The method of claim 9, wherein calculating a position relationship between the pixel point and a reference point according to the position of the pixel point to obtain a compensation index comprises:
calculating the difference value between the abscissa of the pixel point and the abscissa of the reference point to obtain a row difference; calculating the difference value between the vertical coordinate of the pixel point and the vertical coordinate of the reference point to obtain a column difference; wherein the row difference and column difference constitute the compensation index;
the obtaining of the compensation data corresponding to the compensation index includes: and acquiring compensation data corresponding to the compensation index from a preset compensation matrix.
12. A smart device, comprising:
a cover plate;
the light source is arranged in the intelligent equipment and used for emitting light rays to irradiate a target object contacting the cover plate;
the device for acquiring a biometric image according to any one of claims 1 to 7, wherein the device acquires a biometric light signal emitted by the light source and reflected by the target object.
13. A display device, comprising:
a display panel for emitting light to irradiate a target object contacting the display panel;
the device for capturing biometric images as claimed in any one of claims 1 to 7, wherein the device captures biometric light signals emitted from the display panel and reflected by the target object.
14. The display device according to claim 13, wherein the display panel is any one of an OLED panel, an LED panel, and an LCD panel.
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