CN208028993U

CN208028993U - Pixel unit, image sensor chip and imaging system

Info

Publication number: CN208028993U
Application number: CN201820169283.6U
Authority: CN
Inventors: 徐渊; 黄志宇; 漆晓峰; 刘诗琪; 陈享
Original assignee: Shenzhen City Light Micro Technology Co Ltd
Current assignee: Optical Micro Information Technology Hefei Co ltd
Priority date: 2018-01-31
Filing date: 2018-01-31
Publication date: 2018-10-30
Anticipated expiration: 2028-01-31

Abstract

A kind of pixel unit of the application offer, image sensor chip and imaging system, pixel unit include：Substrate；Photodiode；First voltage signal output module comprising first switch, first switch connect photodiode；And second voltage signal output module comprising second switch, second switch connect photodiode；First voltage signal output module exports the voltage signal that first voltage signal indicates ambient light, when obtaining the voltage signal of reflected light of testee, it controls first switch and closes and control second switch opening, second voltage signal output module exports the voltage signal that second voltage signal indicates reflected light, reflects photoelectric signal virtual value according to first voltage signal and second voltage signal acquisition.The application can improve the accuracy of the measurement of the depth information of testee, can be suitable for more complex environment so that application range of products is more extensive.

Description

Pixel unit, image sensor chip and imaging system

Technical field

This application involves image domains more particularly to pixel unit, image sensor chip and imaging systems.

Background technology

In recent years, visual sensor with depth information perception is in artificial intelligence, unmanned, video monitoring, virtual The application in the fields such as reality is continuously increased.The robot vision perceived with depth information is embodied in go far towards to complete At machine learning in artificial intelligence and training, unmanned middle obstacle recognition and organism Activity recognition, video monitoring system In crowd state is analyzed, dynamic 3 D stereo in real time is established in the monitoring and management in crowded place, virtual reality and is handed over Mutual formula environment.Had much using the mode that intelligent CMOS image sensor obtains depth information, such as interferometry (Interferometry), triangulation (Triangulation), binocular stereo vision (Binocular), flight time measurement (Time of Flight).Interferometry illuminates target scene using coherent light, and the jamming pattern light of generation is for realizing accurate Distance estimations.But interferometry needs to configure split-hair visible light when measuring, error must be controlled in nanometer quantity Grade, and it is extremely limited apart from depth, and practical application scene cannot be satisfied requirement, and application is extremely limited.Triangulation is based on light Geometrical relationship (active triangulation, such as laser triangulation and fringe projection) between source and sensor module, but its Maximum distance is limited to datum line parameter, such as the distance between the optical element of system, therefore needs design one in application Extremely compact system module, it is difficult to large-scale application.Triangulation simultaneously and interferometry are required for a scan mechanism, no Conducive to high speed, low-power consumption, compact systems it is integrated.Binocular vision is simulation human vision principle, is seen from two or more points An object is examined, the image obtained under different visual angles passes through principle of triangulation according to the matching relationship of pixel between image The offset between pixel is calculated to obtain the three-dimensional information of object, the depth information of object has been obtained, has calculated object and phase Actual range between machine.Although binocular stereo vision is widely applied in various fields in recent years, binocular tri-dimensional Feel needs stabilised platform to complete camera calibration, in addition feature point extraction, Stereo matching and three-dimensional reconstruction part need hardware (FPGA, DSP etc.) auxiliary completes a large amount of evaluation work, there is the defects of operand and excessive power consumption.

Depth transducer based on flight time measurement, it is a series of with certain duty by being continuously transmitted to target object The laser pulse of ratio, laser pulse return after being irradiated to target object, and the laser arteries and veins returned from object is then received with sensor Punching extracts depth information by flight (round-trip) time of exploring laser light pulse or phase bits in-migration.Flight time measurement is deep Degree sensor is divided into two classes：Direct flight time measurement (TOF) measures (ITOF, or referred to as phase type with the indirect flight time Flight time measurement).The direct common mode of flight time measurement is the time measured laser pulse and flown in space, so It can be obtained at a distance from point-to-point transmission with this flight time and light velocity multiplication afterwards.Main be achieved in that utilizes single-photon avalanche photoelectricity The sensitive optoelectronic response characteristic of diode (Single Photon Avalanche Diode, SPAD), in single photon detection, Generally single-photon avalanche photodiode (SPAD) is required to be biased under the Geiger mode angular position digitizer of high-gain, reverse bias voltage has surpassed The avalanche breakdown voltage of device itself is crossed, numerical value is generally more than ten volts to 20 volt ranges.The realization of this technology by It is formed on the limitation of semiconductor device technology, common production line cannot be satisfied requirement, and the requirement to design is high, always not Obtain big breakthrough, it is difficult to large-scale promotion and application.SPAD is very sensitive to ambient light, and snowslide will occur for faint light, Larger avalanche current is generated, is unfavorable for using in outdoor environment, is influenced by ambient light very big；A large amount of auxiliary are needed simultaneously Circuit, such as the quenching circuit of protecting device not to be broken down by high-voltage, calculate high-precision (the Time to Digital of photon numbers Converter, TDC) circuit unit.SPAD dot structures and its auxiliary circuit cause pixel filling rate is relatively low to be unfavorable on a large scale It is integrated；And directly time flight measurement show that depth information needs a large amount of calculating time, is unfavorable for realizing real time processed images, It is difficult to the ability for having extract real-time depth information.

The indirect flight time measures the laser pulse that (ITOF) sends laser pulse by measurement and reflected through measured target Between phase difference extract depth information, i.e., laser pulse is converted into two laser tested apart from the upper turnaround time The phase difference of pulse realizes extraction of depth information.ITOF deep vision sensors do not need single-photon avalanche photodiode, Common photodiode (photodiode, PD) can be completed to receive the detection of light, and snowslide can be generated by eliminating single photon The defect of electric current, therefore resist ambient light ability with preferable.The indirect flight time measures the phasometer by getting When calculating depth information, calculation amount is smaller, it can be achieved that real time processed images, and calculating process does not need a large amount of additional circuit branch It holds, improves accounting of the photodiode in the domain of rear end, therefore possess higher pixel filling rate, indirect time flight is surveyed Amount technology from several centimetres to tens a meter range possess higher distance measurement accuracy.Therefore the indirect flight time fathoms The research of sensor has great significance to the realization of depth transducer, while in artificial intelligence, unmanned, video prison There are higher application value and wide foreground in the fields such as control, virtual reality.

Referring to Fig. 1, in the prior art, the indirect flight time measures using traditional CMOS 4T-APS (4Transistor Active Pixel Sensor, 4 transistor active element sensors) structure, the structure possess photoelectricity two Pole pipe PD, charge transfer transistor M_TG, reset transistor M_RS, source follower transistor M_SFWith gating transistor M_SEL, and Only there are one floating diffusion regions (Floating Diffusion, FD).This pixel cell structure was applied in the indirect flight time Sensor fathom when obtaining depth information, if ambient light is too strong, can be interfered, seriously affect by ambient light Measure the accuracy of the image depth information of object, complicated outdoor environment can not be suitable for so that the scope of application of product compared with It is narrow.

Invention content

A kind of pixel unit of the application offer, image sensor chip and imaging system can solve to measure now When image depth information using 4 traditional transistor active element sensors there are poor anti jamming capabilities when ambient light is stronger because It can influence the accuracy measured for the interference of ambient light, complicated outdoor environment can not be suitable for and application range of products is narrow The problem of.

According to the application's in a first aspect, the application provides a kind of pixel unit, pixel unit includes：Substrate；Photoelectricity two Pole pipe is set in substrate, to convert the optical signal being incident on photodiode to voltage signal；First voltage Signal output module is used to be incident on the light conversion first voltage signal of photodiode comprising first switch, first The input terminal of switch connects photodiode, when first switch is opened, the exportable first voltage signal of output end of first switch； And second voltage signal output module, it is used to acquisition and is incident on the light output of photodiode be second voltage signal, Including second switch, the input terminal of second switch connects photodiode, and when second switch is opened, the output end of second switch can Export second voltage signal；Wherein, when obtaining the voltage signal of ambient light, control pixel unit receives ambient light, photoelectricity two Ambient light is converted to voltage signal by pole pipe, and control first switch is opened and control second switch is closed, first voltage signal Output module output first voltage signal is the voltage signal for indicating ambient light, when the voltage letter for the reflected light for obtaining testee Number when, control pixel unit receives reflected light, and photodiode converts the reflected light into voltage signal, and control first switch is closed And control second switch is opened, second voltage signal output module output second voltage signal is the voltage letter for indicating reflected light Number, the second voltage for comparing the first voltage signal for indicating ambient light and indicating reflected light is believed to obtain proportionality coefficient, when wanting When obtaining the effective voltage signal of reflected light, reflection photoelectric signal virtual value can be obtained in conjunction with proportionality coefficient.

Preferably, photodiode is set to the center of substrate, the first switch of first voltage signal output module For the first transmission transistor, the first transmission transistor is set in substrate and is set to the side of photodiode, and first passes The voltage signal that defeated transistor accumulates photodiode with photodiode-couple exports, second voltage signal output module Second switch be the second transmission transistor, the second transmission transistor is set in substrate and symmetrical first transmission transistor is set It is placed in the other side of photodiode, the second transmission transistor and voltage of the photodiode-couple to accumulate photodiode Signal exports.

Preferably, first voltage signal output module further includes：First floating diffusion region is set in substrate and sets It is placed in side of first transmission transistor far from photodiode, wherein the first transmission transistor is by the first of photodiode Voltage signal is transferred to the first floating diffusion region and is preserved；First reset transistor is set in substrate and couples photoelectricity two Pole pipe, the first voltage signal to preserve the first floating diffusion region reset；First source following transistor, control End the first floating diffusion region of connection, input terminal connect the first reset transistor；And first gating transistor, input terminal connect The output end of the first source following transistor is connect, the output end of the first gating transistor exports first voltage signal；Second voltage Signal output module further includes：Second floating diffusion region, is set in substrate and to be set to the second transmission transistor separate The side of photodiode, wherein the second voltage signal of photodiode is transferred to the second floating by the second transmission transistor Diffusion region is preserved；Second reset transistor, is set on substrate and couples photodiode, to by the second floating diffusion The second voltage signal that area preserves is resetted；Second source following transistor, control terminal connect the second floating diffusion region, Input terminal connects the second reset transistor；And second gating transistor, input terminal connect the second source following transistor The output end of output end, the second gating transistor exports second voltage signal.

Preferably, first voltage signal output module further includes：First releases transistor, is set in substrate and connects Photodiode is used for when pixel unit is in idle condition, and photodiode is received voltage caused by ambient light Signal discharges；Second voltage signal output module further includes：Second releases transistor, is set in substrate and connects photoelectricity Diode is used for when pixel unit is in idle condition, and photodiode is received voltage signal caused by ambient light It discharges；Wherein, it before calculating and obtaining reflected light virtual value, is released by opening first and transistor and second is released transistor By pixel unit during idle time because the stored charge that ambient light generates discharges.

Preferably, photodiode is square and is set to the center of substrate, and the first transmission transistor is set to The left side of photodiode, the first floating diffusion region are set to side of first transmission transistor far from photodiode, and second Symmetrical first transmission transistor of transmission transistor is set to the right side of photodiode, and the second floating diffusion region symmetrical first is floated Diffusion region is set to side of second transmission transistor far from photodiode, and the first transistor of releasing is set to photodiode Upside, the second transistor of releasing of transistor symmetrical first of releasing is set to the downside of photodiode.

Preferably, photodiode is calendering electric diode.

According to the second aspect of the application, the application provides a kind of image sensor chip, and image sensor chip includes： Pel array comprising multiple pixel units as described above, pixel unit output voltage signal；Bias unit, be used for for Image sensor chip provides bias voltage；AD conversion unit, the voltage signal for exporting pixel unit are converted to number Word signal connects pixel unit；Scanning element, the digital signal for gating simultaneously output pixel array connect pixel battle array Row；Control unit connects and controls pel array, AD conversion unit, scanning element and bias unit work to obtain And output digit signals；Depth information computing unit is used to carry out operation acquisition according to the digital signal that pixel unit exports The range information of testee connects control unit；Output unit is used for distance information transmission to next stage application Layer connects depth information computing unit；Wherein, system opens laser emitting source, emits the time span through ovennodulation every time For T₀Laser pulse, control unit control pixel unit first voltage signal output module first switch open and The second switch of second voltage signal output module is closed, and first voltage signal output module exports first voltage signal, modulus Converting unit converts first voltage signal to the first digital signal, in conjunction with proportionality coefficient by the first digital signal according to setting side Formula is converted to the virtual value U of the first digital signal₀, control unit controls the of the first voltage signal output module of pixel unit One switch is closed and the second switch of second voltage signal output module is opened, second voltage signal output module output second Voltage signal, AD conversion unit convert second voltage signal to the second digital signal, digital by second in conjunction with proportionality coefficient Signal is converted to the virtual value U of the second digital signal according to setting means_i；The first of scanning element gating and output pixel unit The virtual value U of digital signal₀And second digital signal virtual value U₁, depth information computing unit is according to formula：The range information L of the corresponding testee of each pixel unit can be calculated, be also both by Survey the depth information of object, wherein c is the light velocity.

Preferably, AD conversion unit includes the correlated double sampling circuit of corresponding adjacent two pixel units setting, related Dual-sampling circuit includes：The positive input input of the first operational amplifier and its peripheral circuit, the first operational amplifier is inclined The biasing voltage signal of unit offer is set, the negative input of the first operational amplifier passes through two adjacent pictures of the first capacitance connection First gating transistor of plain unit, it is in parallel between the negative input and output end of the first operational amplifier to be equipped with third switch And second capacitance, it is in parallel between the negative input and output end of the first operational amplifier to be equipped with the 4th switch and third electricity Hold, in parallel between the negative input and output end of the first operational amplifier to be equipped with the 5th switch, the first operational amplifier is born The first voltage signal of two pixel units is received to input terminal, the output end of the first operational amplifier exports the first digital signal； Second operational amplifier and its peripheral circuit, the biasing of the positive input input bias unit offer of second operational amplifier Voltage signal, the negative input of second operational amplifier pass through the second of two adjacent pixel units of the 4th capacitance connection and gate Transistor, it is in parallel between the negative input and output end of second operational amplifier to be equipped with the 6th switch and the 5th capacitance, the It is in parallel between the negative input of two operational amplifiers and output end to be equipped with the 7th switch and the 6th capacitance, the second operation amplifier In parallel between the negative input of device and output end to be equipped with the 8th switch, the negative input of second operational amplifier receives two pictures The output end of the second voltage signal of plain unit, second operational amplifier exports the second digital signal.

Preferably, first voltage signal output module further includes：First floating diffusion region is set in substrate and sets It is placed in side of first transmission transistor far from photodiode, wherein the first transmission transistor is by the first of photodiode Voltage signal is transferred to the first floating diffusion region and is preserved；First reset transistor is set in substrate and couples photoelectricity two Pole pipe, the first voltage signal to preserve the first floating diffusion region reset；First source following transistor, control End the first floating diffusion region of connection, input terminal connect the first reset transistor；And first gating transistor, input terminal connect The output end of the first source following transistor is connect, the output end of the first gating transistor exports first voltage signal；Second voltage Signal output module further includes：Second floating diffusion region, is set in substrate and to be set to the second transmission transistor separate The side of photodiode, wherein the second voltage signal of photodiode is transferred to the second floating by the second transmission transistor Diffusion region is preserved；Second reset transistor, is set on substrate and couples photodiode, to by the second floating diffusion The second voltage signal that area preserves is resetted；Second source following transistor, control terminal connect the second floating diffusion region, Input terminal connects the second reset transistor；And second gating transistor, input terminal connect the second source following transistor The output end of output end, the second gating transistor exports second voltage signal；Wherein, control unit connects the first transmission transistor Control terminal, the control terminal of the first reset transistor, the control terminal, the second transmission transistor of the first gating transistor control It holds, the control terminal of the control terminal of the second reset transistor and the second gating transistor.

Preferably, first voltage signal output module further includes：First releases transistor, is set in substrate and connects Photodiode is used for when pixel unit is in idle condition, and photodiode is received voltage caused by ambient light Signal discharges；Second voltage signal output module further includes：Second releases transistor, is set in substrate and connects photoelectricity Diode is used for when pixel unit is in idle condition, and photodiode is received voltage signal caused by ambient light It discharges；Wherein, it first releases transistor and the second transistor of releasing is controlled by control unit, is obtained opening laser pulse Before the useful signal of pixel unit, control unit is released by opening first and transistor and second releases transistor by pixel list Member is during idle time because the stored charge that ambient light generates discharges.

Preferably, photodiode is square and is set to the center of substrate, and the first transmission transistor is set to The left side of photodiode, the first floating diffusion region are set to side of first transmission transistor far from photodiode, and second Symmetrical first transmission transistor of transmission transistor is set to the right side of photodiode, and the second floating diffusion region symmetrical first is floated Diffusion region is set to side of the second transistor far from photodiode, and the first transistor of releasing is set to the upper of photodiode Side, the second transistor of releasing of transistor symmetrical first of releasing are set to the downside of photodiode.

According to the third aspect of the application, the application provides a kind of imaging system comprising image sensing as described above Device chip and laser emitter.

According to the fourth aspect of the application, the application provides a kind of forming method of pixel unit, and method includes：Setting lining Bottom；Photodiode is set, is set in substrate, to convert the optical signal being incident on photodiode to voltage Signal；First voltage signal output module is set, is used to be incident on the light conversion first voltage signal of photodiode, Including first switch, the input terminal of first switch connects photodiode, and when second switch is opened, the output end of first switch can Export first voltage signal；And setting second voltage signal output module, it is used to obtain the light for being incident on photodiode Output is second voltage signal comprising the input terminal of second switch, second switch connects photodiode, and second switch is opened When, the exportable second voltage signal of output end of second switch；Wherein, when obtaining the voltage signal of ambient light, pixel is controlled Unit receives ambient light, and ambient light is converted to voltage signal by photodiode, and control first switch is opened and control second Switch is closed, and first voltage signal output module output first voltage signal is the voltage signal for indicating ambient light, when acquisition quilt When surveying the voltage signal of the reflected light of object, control pixel unit receives reflected light, and photodiode converts the reflected light into electricity Signal is pressed, control first switch is closed and control second switch is opened, and second voltage signal output module exports second voltage Signal is the voltage signal for indicating reflected light, the second electricity for comparing the first voltage signal for indicating ambient light and indicating reflected light Pressure letter, when the effective voltage signal of reflected light to be got, can be obtained reflection to obtain proportionality coefficient in conjunction with proportionality coefficient Photoelectric signal virtual value.

According to the 5th of the application the aspect, the application provides a kind of depth information measuring method, and method includes：By as above The pixel unit obtains the voltage signal of the expression ambient light under current environment and the reflection photovoltage for indicating testee The proportionality coefficient of signal；System opens laser emitting source, and it is T to emit the time span through ovennodulation every time₀Laser pulse, control The first switch opening of the first voltage signal output module of pixel unit processed and the second of second voltage signal output module Switch is closed, and obtained first voltage signal after light emitting diode transmitting photo-signal is obtained, and first voltage signal is converted into the First digital signal is converted to the virtual value of the first digital signal in conjunction with proportionality coefficient by one digital signal according to setting means U₀；The first switch for controlling the first voltage signal output module of pixel unit is closed and second voltage signal output module Second switch is opened, and the second voltage signal obtained after light emitting diode transmitting photo-signal is obtained, and second voltage signal is converted into Second digital signal is converted to the virtual value of the second digital signal in conjunction with proportionality coefficient by the second digital signal according to setting means U₁；Gate the virtual value U of simultaneously the first digital signal of output pixel unit₀And second digital signal virtual value U₁；According to public affairs Formula：The range information L of the corresponding testee of each pixel unit is calculated, is also both depth Information, wherein c is the light velocity.

Preferably, further include step before the step of control emits the laser pulse through ovennodulation：Pixel is opened in control The first of unit release transistor and second release transistor by pixel unit during idle time because ambient light generate accumulation Charge discharges.

The advantageous effect of the application is：By the way that first voltage signal output module and the output of second voltage signal is arranged Module, the first switch of control first voltage signal output module and the second switch of second voltage signal output module are beaten On or off is closed, and output indicates that the first voltage signal of ambient light and output indicate the second voltage signal of reflected light, The virtual value that the voltage signal for indicating reflected light can be obtained according to the first voltage signal and second voltage signal, with this voltage The virtual value of signal is used as the measuring and calculating of depth information, improves the accuracy for the depth information for measuring object, and can be applicable in In more complex environment, but also should the technology product the scope of application it is more extensive.

Description of the drawings

Fig. 1 is the structural schematic diagram of traditional 4 transistor active element sensors；

Fig. 2 is the structural schematic diagram of pixel unit in the application first embodiment；

Fig. 3 is the structural schematic diagram of pixel unit in the application second embodiment；

Fig. 4 is the equivalent circuit schematic of Fig. 3；

Fig. 5 is the schematic top plan view of the structure of pixel unit in the application second embodiment；

Fig. 6 is the knot that pixel unit is formed by the section on in-plane in Z axis and X-axis in the application second embodiment Structure schematic diagram；

Fig. 7 is the equivalent circuit schematic of Fig. 6；

Fig. 8 is the schematic diagram of image sensor chip in the application 3rd embodiment；

Fig. 9 is the circuit diagram that the pixel unit in Fig. 8 is connect with AD conversion unit；

Figure 10 is the flow chart of the forming method of the pixel unit shown in the application fourth embodiment；

Figure 11 is the flow chart that the application the 7th implements the depth information measuring method exemplified.

Reference sign：3 photodiode PD first voltages signal output module of substrate, 1 first transmission transistor M_TX0 First floating diffusion region V_FD0First reset transistor M_RS0First source following transistor M_SF0First gating transistor M_SEL0First Release transistor M_TXD02 second transmission transistor M of second voltage signal output module_TX1Second floating diffusion region V_FD1Second is multiple Bit transistor M_RS1Second source following transistor M_SF1Second gating transistor M_SEL1Second releases transistor M_TXD1First N-type from The 4th N-type ion area 304P of 301 second N-type ion area of sub-district, 302 third N-type ion area 303 falls into 305 N-type buried layer 306 of area 604 control unit of pel array 601 bias unit, 602 AD conversion unit, 603 scanning element, 605 depth information computing unit 606 output unit, 607 first the first capacitances of operational amplifier OTA1 C_s0Third switch S_rst0Second capacitance C_fd04th switch S_fd0 Third capacitance C '_fd05th switch S_fd0The 4th capacitance C of second operational amplifier OTA2_s16th switch S_rst15th capacitance C_fd1The Seven switch S_fd16th capacitance C '_fd18th switch S '_fd1。

Specific implementation mode

The application is described in further detail below by specific implementation mode combination attached drawing.

The design of the application is：It being capable of measuring environment light and measurement object by being arranged in the structure of traditional 4T-APS The pixel cell structure of body reflected light can promote the accuracy for measuring image depth information so that the use scope of product is more Extensively.

Embodiment one：

Referring to Fig. 2, pixel unit includes：Substrate 203, photodiode PD, first voltage signal output module 201 with And second voltage signal output module 202.

Photodiode PD is set in substrate 203, and the optical signal will be incident on photodiode PD turns Turn to voltage signal；First voltage signal output module 201 is used to be incident on the first electricity of light conversion of photodiode PD Press signal comprising the input terminal of first switch, first switch connects photodiode PD, and when first switch is opened, first opens The exportable first voltage signal of output end of pass；Second voltage signal output module 202 is used for acquisition and is incident on two pole of photoelectricity The light output of pipe PD is second voltage signal comprising the input terminal of second switch, second switch connects photodiode PD, the When two switches are opened, the exportable second voltage signal of output end of second switch.

Substrate 203 is used to form device architecture or chip circuit, and substrate 203 can be semiconductor base, semiconductor base Including silicon substrate, silicon-Germanium substrate, silicon carbide substrates, silicon-on-insulator (SOI) substrate, germanium on insulator (GOI) substrate, glass lined Bottom or III-V compound substrate (such as silicon nitride or GaAs etc.).Substrate 203 or body substrate, i.e. silicon substrate, silicon Germanium substrate or silicon carbide substrates.In other embodiments, substrate 203 can also be that silicon-on-insulator substrate or germanium on insulator serve as a contrast Bottom.In other embodiments, substrate 203 can also include semiconductor base and is formed in by epitaxy technique semiconductor-based The epitaxial layer of bottom surface.

In the present embodiment, substrate 203 includes：P-type single crystalline silicon substrate (p-type substrate) and p-type epitaxial layer (p-epitaxial layer)。

Photodiode PD is set in substrate 203, and photodiode PD is formed by ion implantation technology, moreover, logical The energy and concentration for crossing control ion implanting can control the depth and injection range of ion implanting, to control two pole of photoelectricity The depth and thickness of pipe PD.

In the present embodiment, photodiode PD is calendering electric diode (Pinned Photodiode, PPD).Two pole of photoelectricity Doped with N-type ion in pipe PD, the N-type ion includes phosphonium ion, arsenic ion or antimony ion.In addition, photodiode PD phases For a thin layer of P+ layers more than the surface layer of conventional photodiode PD so that pinned photodiode PD is on the one hand relatively traditional Photodiode PD have smaller dark current, on the other hand can form complete depletion of accumulation area, overcome output figure As the problem of lag.

The first switch of first voltage signal output module 201 is the first transmission transistor, and second voltage signal exports mould The second switch of block 202 is the second transmission transistor.Photodiode PD is set to the center of substrate 203, the first transmission Transistor is set in substrate 203 and is set to the side of photodiode PD, the first transmission transistor and photodiode PD couplings are exported with the voltage signal for accumulating photodiode PD, and the second transmission transistor is set in substrate 203 and right The other side for claiming the first transmission transistor to be set to photodiode PD, the second transmission transistor are coupled with photodiode PD With the voltage signal output for accumulating photodiode PD.

The operation principle of the present embodiment is illustrated with reference to Fig. 2.

When obtaining the voltage signal of ambient light, control pixel unit receives ambient light, and photodiode PD is by ambient light Voltage signal is converted to, control first switch is opened and control second switch is closed, and first voltage signal output module 201 is defeated It is the voltage signal for indicating ambient light to go out first voltage signal, when obtaining the voltage signal of reflected light of testee, control Pixel Dan Yaoyuan receives reflected light, and photodiode PD converts the reflected light into voltage signal, control first switch close and It controls second switch to open, it is the voltage letter for indicating reflected light that second voltage signal output module 202, which exports second voltage signal, Number, the second voltage for comparing the first voltage signal for indicating ambient light and indicating reflected light is believed to obtain proportionality coefficient, when obtaining When getting the effective voltage signal of reflected light, reflection photoelectric signal virtual value can be obtained in conjunction with proportionality coefficient.

Embodiment two：

Fig. 3 and Fig. 4 are please referred to, pixel unit includes：Substrate 203, photodiode PD, first voltage signal output module 201 and second voltage signal output module 202.

Substrate 203 is used to form device architecture or chip circuit, and substrate 203 can be semiconductor base, semiconductor base Including silicon substrate, silicon-Germanium substrate, silicon carbide substrates, silicon-on-insulator (SOI) substrate, germanium on insulator (GOI) substrate, glass lined Bottom or III-V compound substrate (such as silicon nitride or GaAs etc.).Substrate 203 or body substrate, i.e. silicon substrate, silicon Germanium substrate or silicon carbide substrates.In other embodiments, substrate 203 can also be that silicon-on-insulator substrate or germanium on insulator serve as a contrast Bottom.In other embodiments, substrate 203 can also include semiconductor base and be formed in semiconductor base by epitaxy technique The epitaxial layer on surface.

Photodiode PD is set in substrate 203, to the optical signal conversion that will be incident on photodiode PD For voltage signal.In the present embodiment, photodiode PD is calendering electric diode PD (Pinned Photodiode, PPD).Light Doped with N-type ion in electric diode PD, the N-type ion includes phosphonium ion, arsenic ion or antimony ion.In addition, two pole of photoelectricity Pipe PD relative to conventional photodiode PD surface layer more than a thin layer of P+ layers so that pinned photodiode PD one side phases There is smaller dark current to traditional photodiode PD, on the other hand can form complete depletion of accumulation area, overcome The problem of exporting picture lag.

Please continue to refer to Fig. 3 and Fig. 4, first voltage signal output module 201 includes：First transmission transistor M_TX0, One floating diffusion region V_FD0, the first reset transistor M_RS0, the first source following transistor M_SF0And first gating transistor M_SEL0。

First voltage signal output module 201 includes：First transmission transistor M_TX0, be set in substrate 203 and It is set to the side of photodiode PD, the first transmission transistor M_TX0It is coupled with photodiode PD with by photodiode PD The voltage signal of accumulation exports；First floating diffusion region V_FD0, it is set in substrate 203 and is set to the first transmission crystal Pipe V_FD0Side far from photodiode PD, wherein the first transmission transistor V_FD0The first voltage of photodiode PD is believed Number it is transferred to the first floating diffusion region V_FD0It is preserved；First reset transistor M_RS0, it is set in substrate 203 and couples photoelectricity Diode PD, to by the first floating diffusion region V_FD0The first voltage signal of preservation is resetted；First source following transistor M_SF0, the first floating diffusion region V of control terminal connection_FD0, the first reset transistor M of input terminal connection_RS0；And first gating Transistor M_SEL0, the first source following transistor M of input terminal connection_SF0Output end, the first gating transistor M_SEL0Output End output first voltage signal.

Further, first voltage signal output module 201 includes：First releases transistor M_TX1, it is set to substrate In 203 and photodiode PD is connected, is used for when pixel unit is in idle condition, photodiode PD is received into environment Voltage signal caused by light discharges.

In the present embodiment, the first transmission transistor M_TX0, the first reset transistor M_RS0, the first source following transistor M_SF0 And the first gating transistor M_SEL0It is metal-oxide-semiconductor.

Second voltage signal output module 202 includes：Second transmission transistor M_TX1, the second floating diffusion region V_FD1, second Reset transistor M_RS1, the second source following transistor M_SF1And the second gating transistor M_SEL1。

Second voltage signal output module 202 includes：Second transmission transistor M_TX1, be set in substrate 203 and Symmetrical first transmission transistor M_TX0It is set to the other side of photodiode PD, the second transmission transistor M_TX1With photodiode PD couplings are exported with the voltage signal for accumulating photodiode PD；Second floating diffusion region V_FD1, it is set in substrate 203 And it is set to the second transmission transistor M_TX1Side far from photodiode PD, wherein the second transmission transistor M_TX1By light The second voltage signal of electric diode PD is transferred to the second floating diffusion region V_FD1It is preserved；Second reset transistor V_FD1, It is set on substrate 203 coupling photodiode PD, to by the second floating diffusion region V_FD1The second voltage signal of preservation into Row resets；Second source following transistor M_SF1, the second floating diffusion region V of control terminal connection_FD1, it is multiple that input terminal connects second Bit transistor；And the second gating transistor M_SEL1, the second source following transistor M of input terminal connection_SF1Output end, Two gating transistor M_SEL1Output end export second voltage signal.

Further, second voltage signal output module 202 includes：Second releases transistor M_TXD1, it is set to substrate In 203 and photodiode PD is connected, is used for when pixel unit is in idle condition, photodiode PD is received into environment Voltage signal caused by light discharges.

In the present embodiment, the second transmission transistor M_TX1, the second reset transistor M_RS1, the second source following transistor M_SF1 And the second gating transistor M_SEL1It is metal-oxide-semiconductor.

Referring to Fig. 5, Fig. 5 is the structure top view of pixel unit.Photodiode PD is square and is set to substrate Reference axis is established in 203 center using the center of photodiode PD as the center of circle.Wherein, it is parallel on the square The direction of lower two sides is X-axis, and the direction for being parallel to the square left and right sides is Y-axis, is formed perpendicular to the X-axis and Y-axis Plane be Z axis.It can be seen from figure 4 that the direction extended in parallel of being turned right using X-axis is up prolonged as the positive direction of X-axis with Y-axis The direction stretched is the positive direction of Y-axis.

First transmission transistor M_TX0It is set to the left side of photodiode PD, the first floating diffusion region V_FD0It is set to first Transmission transistor M_TX0Side far from photodiode PD, the second transmission transistor M_TX1Symmetrical first transmission transistor M_TX0If It is placed in the right side of photodiode PD, the second floating diffusion region V_FD1Symmetrical first floating diffusion region V_FD0It is set to the second transmission crystalline substance Body pipe M_TX1Side far from photodiode PD, first releases transistor M_TXD0It is set to the upside of photodiode PD, second Release transistor M_TXD1Symmetrical first releases transistor M_TXD0It is set to the downside of photodiode PD.Also it is both that the first transmission is brilliant Body pipe M_TX0And the second transmission transistor M_TX1It is symmetrical with X-axis to be configured, first releases transistor M_TXD0And second release Transistor M_TXD1Y-axis is symmetrical with to be configured.

Fig. 3 and Fig. 4 are please referred to, Fig. 3 is that the structure of pixel unit is formed by the section on in-plane in Z axis and X-axis Figure.Substrate 203 includes：P-type single crystalline silicon substrate and p-type epitaxial layer.Photodiode PD is calendering electric diode PD (Pinned Photodiode, PPD).Photodiode PD is set in substrate 203, and photodiode PD passes through ion implanting Technique is formed, and the P-N-P structures of p-type epitaxial layer, N-type buried layer 306, p-type epitaxial layer are formed.Also that is, on the direction of Z axis, P-type epitaxial layer is formed in P type single crystalline silicon substrates, and N-type buried layer 306 is formed in the center of p-type epitaxial layer, P+ type Sheath is formed in N-type buried layer 306.

Referring to Fig. 3, P falls into area 305 and is arranged in the both sides of N-type buried layer 306.First N-type ion area 301 is formed in In N-type buried layer 306, and the P for connecting N-type buried layer 306 and left side falls into area 305, and the first N-type ion area 301 is as the One floating diffusion region, the P that the second N-type ion area 302 is formed in left side are fallen into area 305.Third N-type ion area 303 is formed in N-type In buried layer 306, and the P for connecting N-type buried layer 306 and right side falls into area 305, and third N-type ion area 303 is used as second Floating diffusion region, the P that the 4th N-type ion area 304 is formed in right side are fallen into area 305.First N-type ion area 301, the second N-type from Sub-district 302, third N-type ion area 303 and the 4th N-type ion area 304 are doped with N+ type ions.

First transmission transistor M_TX0GridIt is formed in the left side of the P+ type sheath.First resets crystal M_RS0's GridThe P for being formed in left side falls into area 305.First source following transistor M_SF0Grid connect first floating diffusion region V_FD0, the first source following transistor M_SF0Drain connect the second N-type ion area 302 and bias voltage, the first source electrode and follow Transistor M_SF0Source level connect the first gating transistor M_SEL0Source electrode.First gating transistor M_SEL0Drain electrode output voltage Signal.

Second transmission transistor M_TX1GridIt is formed in the right side of the P+ type sheath, the second transmission transistor M_TX1 GridSymmetrical first transmission transistor M_TX0It is formed in the right side of the P+ type sheath.Second resets crystal M_RS1Grid The P that pole is formed in right side falls into area 305.Second source following transistor M_SF1Grid connect second floating diffusion region V_FD1, the Two source following transistor M_SF1Drain connect the 2nd N type ions area 302 and bias voltage, the second source following transistor M_SF1Source level connect the second gating transistor source electrode.Second gating transistor M_SEL1Drain electrode output voltage signal.

Fig. 6 and Fig. 7 are please referred to, Fig. 6 is that the structure of pixel unit is formed by Z axis and Y direction on in-plane Sectional view.It can be seen that first releases transistor M_TXD0Grid and second release transistor M_TXD1Grid be symmetrical arranged In the both sides of the P+ type sheath.

The operation principle of the present embodiment is illustrated with reference to Fig. 3 to Fig. 7.

First, it is released transistor M by opening first_TXD0And second release crystal M_TXD1Pipe is by pixel unit in the free time The stored charge that Shi Yinwei ambient lights generate discharges.

Then, it before the signal voltage of acquisition uniline or single-row pixel unit, carries out an ambient light and collects pre- place Reason, detailed process are as follows：It is not turned on Laser emission module, controls the first transmission transistor M_TX0It opens and second transmits crystal Pipe M_TX1It closes, opens the first floating diffusion region V of pixel unit_FD0Part, and time for exposure T₀, export first voltage signal U₀To indicate the voltage signal of ambient light；Laser emission module is opened, the second transmission transistor M is controlled_TX1It opens and first passes Defeated transistor M_TX0It closes, opens the second floating diffusion region V of pixel unit_FD1Part, exposure same time T₀, the second electricity of output Press signal U₁To indicate the voltage signal of the reflected light generated jointly by ambient light and laser pulse, second voltage signal U₁It subtracts First voltage signal U₀It can be obtained the effective voltage that transmitting laser pulse generates.Compare the first voltage signal for indicating ambient light U₀And indicate that the second voltage of reflected light believes U₁To obtain proportionality coefficient, this proportionality coefficient is empirically worth.The present embodiment In, which is also both to indicate that the voltage signal of ambient light occupies the electricity for indicating reflected light about between 3% to 5% Press the ratio of signal between 3% to 5%.As long as the voltage signal of reflected light is combined the proportionality coefficient, you can anti-to obtain The effective voltage for penetrating light is also both that the effective voltage signal of reflected light accounts for second voltage letter U₁95% to 97%.Therefore, only The voltage signal values of reflected light are multiplied by the difference very with proportionality coefficient, you can the effective voltage to obtain reflected light is believed Number.The ambient light resistivity and signal-to-noise ratio of pixel unit can thus be improved.

Embodiment three：

Referring to Fig. 8, image sensor chip includes：Pel array 601, bias unit 602, AD conversion unit 603, Scanning element 604, control unit 605, depth information computing unit 606 and output unit 607.

Pel array 601 comprising multiple pixel units as described above, pixel unit output voltage signal；Biasing is single Member 602, is used to provide bias voltage for image sensor chip；AD conversion unit 603, for export pixel unit Voltage signal is converted to digital signal, connects pixel unit；Scanning element 604, for gate simultaneously output pixel array 601 Digital signal connects 601 chamber unit 605 of pel array, connects and controls pel array 601, AD conversion unit 603, scanning element 604 and the work of bias unit 602 are to obtain simultaneously output digit signals；Depth information computing unit 606, It is used to carry out the range information that operation obtains testee according to the digital signal that pixel unit exports, and connects control unit 605；Output unit 607 is used to, by distance information transmission to next stage application layer, connect depth information computing unit 606。

In the present embodiment, pel array 601 includes 19200 pixel units, is made of 160 × 120 pixel unit.

Further, first voltage signal output module 201 includes：First releases transistor M_TX1, it is set to substrate In 203 and photodiode PD is connected, when being used to pixel unit being in idle condition, photodiode PD receives ambient light Generated voltage signal discharges.

Further, second voltage signal output module 202 includes：Second releases transistor M_TXD1, it is set to substrate In 203 and photodiode PD is connected, when being used to pixel unit being in idle condition, photodiode PD receives ambient light Generated voltage signal discharges.

Referring to Fig. 6, Fig. 6, which is the structure of pixel unit, is formed by the sectional view on in-plane in Z axis and X-axis.Lining Bottom 203 includes：P-type single crystalline silicon substrate and p-type epitaxial layer.Photodiode PD is calendering electric diode PD (Pinned Photodiode, PPD).Photodiode PD is set in substrate 203, and photodiode PD is formed by ion implantation technology, Form the P-N-P structures of p-type epitaxial layer, N-type buried layer 306, P type epitaxial layers.Also that is, on the direction of Z axis, p-type epitaxial layer It is formed in p-type single crystalline silicon substrate, N-type buried layer 306 is formed in the center of p-type epitaxial layer, and P+ type sheath is formed In N types buried layer 306.

Second transmission transistor M_TX1GridIt is formed in the right side of the P+ type sheath, the second transmission transistor M_TX1 GridSymmetrical first transmission transistor M_TX0It is formed in the right side of the P+ type sheath.Second resets crystal M_RS1Grid The P that pole is formed in right side falls into area 305.Second source following transistor M_SF1Grid connect second floating diffusion region, the second source Pole follows transistor M_SF1Drain connect the second N-type ion area 302 and bias voltage, the second source following transistor M_SF1's Source level connects the source electrode of the second gating transistor.Second gating transistor M_SEL1Drain electrode output voltage signal.

Fig. 6 and Fig. 7 are please referred to, Fig. 6 is that the structure of pixel unit is formed by Z axis and Y direction on in-plane Sectional view.It can be seen that first releases transistor M_TXD0Grid and second release transistor M_TXD1GridSymmetrically It is set to the both sides of the P+ type sheath.

Referring to Fig. 9, Fig. 9 is the schematic diagram that adjacent pixel unit shares correlated double sampling circuit.AD conversion unit 603 include the correlated double sampling circuit of corresponding adjacent two pixel units setting, and correlated double sampling circuit includes：

The positive input input of the first operational amplifier OTA1 and its peripheral circuit, the first operational amplifier OTA1 is inclined The biasing voltage signal of the offer of unit 602 is set, the negative input of the first operational amplifier OTA1 passes through the first capacitance C_s0Connection First gating transistor M of two adjacent pixel units_SEL0, the negative input of the first operational amplifier OTA1 and output end it Between in parallel be equipped with third switch S_rst0And the second capacitance C_fd0, the negative input and output end of the first operational amplifier OTA1 Between in parallel be equipped with the 4th switch S_fd0And third capacitance C '_jd0, the negative input of the first operational amplifier OTA1 and output It is in parallel between end to be equipped with the 5th switch S '_fd0, the first of negative input two pixel units of reception of the first operational amplifier OTA1 The output end of voltage signal, the first operational amplifier OTA1 exports the first digital signal；

The positive input input of second operational amplifier OTA2 and its peripheral circuit, second operational amplifier OTA2 is inclined The biasing voltage signal of the offer of unit 602 is set, the negative input of second operational amplifier OTA2 passes through the 4th capacitance C_s1Connection Second gating transistor M of two adjacent pixel units_SEL1, the negative input of second operational amplifier OTA2 and output end it Between in parallel be equipped with the 6th switch S_rst1And the 5th capacitance C_fd1, the negative input and output end of second operational amplifier OTA2 Between in parallel be equipped with the 7th switch S_fd1And the 6th capacitance C '_fd1, the negative input of second operational amplifier OTA2 and output It is in parallel between end to be equipped with the 8th switch S '_fd1, the second of negative input two pixel units of reception of second operational amplifier OTA2 The output end of voltage signal, second operational amplifier OTA2 exports the second digital signal.

In the prior art, each pixel unit is that two above-mentioned correlated sampling circuits is needed to obtain expression environment to sample The voltage signal of light and the voltage signal of reflected light, but the correlated sampling circuit of the present embodiment is used, utilize the present embodiment Correlated sampling circuit shared mechanism, the voltage signal of the expression ambient light of adjacent pixel unit and anti-can be obtained simultaneously The voltage signal of light is penetrated, the depth information for completing two pixels calculates.Specifically, related when needing read-out voltage signal Sample circuit is started to work, and the first gating transistor of control pixel unit Pixel 0 is opened, and the first operational amplification circuit is obtained First digital signal U of output₀, the second gating transistor opening of control pixel unit Pixel 0, the first operation amplifier of acquisition Second digital signal U of circuit output₁, thus complete the calculating of the depth information of a pixel.Then, pixel unit is controlled The first gating transistor of Pixel 1 is opened, and the first digital signal U of the first operational amplification circuit output is obtained₀, control picture The second gating transistor of plain unit Pixel 0 is opened, and the second digital signal U of the first operational amplification circuit output is obtained₁, this Sample just completes the calculating of the depth information of one other pixel.It can be seen that, as long as by scanning element 604 scan odd-numbered line or Then the pixel unit of odd column scans the pixel unit of even number line or even column again, can both pass through the correlated-double-sampling Circuit obtains the voltage signal of strange pixel and idol vegetarian refreshments.Because operational amplifier occupies the bigger area of chip, use This shared mechanism makes adjacent pixel unit share an AD conversion unit 603, substantially reduces correlated double sampling circuit Chip area improves the pixel filling rate of depth image sensor chip.

Scanning element 604 includes row scanning subelement (Vertical Scanner) and column scan subelement (Horizontal Scanner), wherein row scanning son member scanning obtains the pixel unit of row sequence in pel array 601, row Scanning son member scanning obtains the pixel unit of row sequence in pel array 601.

Control unit 605 connects the first transmission transistor M_TX0Control terminal, the first reset transistor M_RS0Control terminal, One gating transistor M_SF0Control terminal, the second transmission transistor M_TX1Control terminal, the second reset transistor M_RS1Control terminal with And the second gating transistor M_SEL1Control terminal.

Wherein, it first releases transistor M_TXD0And second release transistor M_TXD1It is controlled by control unit 605, is opening Before laser pulse obtains the useful signal of pixel unit, control module is released transistor M by opening first_TxD0And second Release transistor M_TXD1By pixel unit during idle time because the stored charge that ambient light generates discharges.

First transmission transistor M_TX0Control terminal, the first reset transistor M_RS0Control terminal, the first gating transistor M_RS0 Control terminal, the second transmission transistor M_TX1Control terminal, the second reset transistor M_RS1Control terminal and second gating crystal Pipe M_SEL1Control terminal refer both to the grid of metal-oxide-semiconductor.

In the present embodiment, depth information computing unit 606 can be by being arranged the circuit in depth image sensor come real Now calculate.In other embodiment, depth information computing unit 606 can by depth image sensor add peripheral circuit, Such as complete being calculated to realize for depth information using FPGA or dsp chip.

Further, imaging sensor further includes image enhancement module (not shown), after imaging sensor exports image, Post-processing is carried out to realize the enhancing of image information to image.

The operation principle of the present invention is illustrated with reference to Fig. 3 to Fig. 9.

First, it is released transistor M by opening first_TXD0And second release transistor M_TXD1By pixel unit in the free time The stored charge that Shi Yinwei ambient lights generate discharges.Then, in acquisition uniline or the signal voltage of single-row pixel unit Before, it carries out an ambient light and collects pretreatment, detailed process is as follows：It is not turned on Laser emission module, control the first transmission crystal Pipe M_TX0Opening and the second transmission transistor M_TX1It closes, opens the first floating diffusion region V of pixel unit_FD0Part, and expose T between light time₀, output first voltage signal U₀To indicate the voltage signal of ambient light；Laser emission module is opened, control second passes Defeated transistor M_TX1Opening and the first transmission transistor M_TX0It closes, opens the second floating diffusion region V of pixel unit_FD1Part, Expose same time T₀, output second voltage signal U₁To indicate the electricity of the reflected light generated jointly by ambient light and laser pulse Press signal, second voltage signal U₁Subtract first voltage signal U₀It can be obtained the effective voltage that transmitting laser pulse generates.Compare Indicate the first voltage signal U of ambient light₀And indicate that the second voltage of reflected light believes U₁To obtain proportionality coefficient, by this ratio Coefficient is empirically worth.It is obtained by multiple authentication, which is also both to indicate environment about between 3% to 5% The voltage signal of light occupies the ratio for the voltage signal for indicating reflected light between 3% to 5%.As long as the voltage of reflected light is believed Number combination proportionality coefficient, you can to obtain the effective voltage of reflected light, be also both that the effective voltage signal of reflected light accounts for second Voltage believes the 95% to 97% of U.Therefore, as long as the voltage signal values of reflected light are multiplied by the difference very with proportionality coefficient, The effective voltage signal of reflected light can be obtained.

Chip powers on, and bias unit 602 starts, and provides stable bias voltage for entire chip, control unit 605 and Laser emission module establishes communication, and AD conversion unit 603, scanning element 604 and output unit 607, which enter, is ready to complete shape State.

Before opening the laser pulse and obtaining the useful signal of the pixel unit, the pretreatment of ambient light is carried out, is had Body is：Control unit 605 controls the first transmission transistor M_TX0, the second transmission transistor M_TX1, the first reset transistor M_RS0, Two reset transistor M_RS1, the first source following transistor M_SF0, the second source following transistor M_SF1, the first gating transistor M_SEL0And the second gating transistor M_SEL1It is closed, control first is released transistor M_TXD0And second release crystal Pipe M_TXD1It opens, by imaging sensor because the charge discharging resisting of ambient light accumulation falls.Then, control unit 605 controls pixel list First reset transistor M of member_RS0And the second reset transistor M_RS1It opens so that the first floating diffusion region V_FD0And second Floating diffusion region V_FD1The voltage amplitude of accumulation closes the first reset transistor M after reset_RS0And the second reset transistor M_RS1。

Referring to Fig. 7, system opens laser emitting source, it is T to emit the time span through ovennodulation every time₀Laser arteries and veins Punching, control unit 605 control the first transmission transistor M_TX0Open setting time T_on, then, in the modulation laser pulse set Effectively after, the first transmission transistor M is closed_TX0, control second transmission transistor of control unit 605 M_TX1When opening setting Between T_on, close the second transmission transistor M_TX1.Open the first gating transistor M_SEL0, obtain the first floating diffusion region V_FD0Accumulation First voltage signal, AD conversion unit 603 convert first voltage signal into digital signal, according to the ratio system obtained before Number, obtains the first digital signal of virtual value U of digital signal₀, open the second gating transistor M_SEL1, obtain the second floating diffusion Area V_FD1The second voltage signal of accumulation, 603 second voltage signal of AD conversion unit are converted to digital signal, according to obtaining before The proportionality coefficient taken obtains the second digital signal of virtual value U of digital signal₁。

Row scanning subelement/column scan subelement obtains the first digital signal U of pixel unit₀And second digital signal U₁, because the correlated double sampling circuit of AD conversion unit 603 is set using the circuit of the shared mechanism of adjacent pixel unit Meter, so row scanning subelement run-down can only obtain the first digital signal U of the pixel unit of odd-numbered line or even number line₀ And the second digital signal U₁, column scan subelement run-down can only obtain the of the pixel unit of odd-numbered line or even number line One digital signal U₀And the second digital signal U₁.Depth information computing unit 606 is according to formula：? The range information L of the corresponding testee of each pixel unit is calculated, is also both the depth information of testee, In, c is the light velocity.The depth information of testee is transferred to the application layer of next stage by output unit 607.

Embodiment five：

The application proposes a kind of imaging system comprising image sensor chip and laser emitter as described above.

The imaging system of the present embodiment can be applied to robot vision field, automatic Pilot field, field of video monitoring, 3D imaging fields, gesture identification field.

Embodiment six：

Referring to Fig. 10, the application proposes a kind of forming method of pixel unit, including：

Step S601：Substrate is set；

Step S602：Photodiode PD is set, is set in substrate, makes it photodiode PD will be incident in On optical signal be converted into voltage signal；

Step S603：First voltage signal output module is set, is used to be incident on the light conversion of photodiode PD First voltage signal comprising the input terminal of first switch, first switch connects photodiode PD, when second switch is opened, The exportable first voltage signal of output end of first switch；And

Step S604：Be arranged second voltage signal output module, be used for obtain be incident on photodiode PD light it is defeated Go out for second voltage signal comprising the input terminal of second switch, second switch connects photodiode PD, and second switch is opened When, the exportable second voltage signal of output end of second switch.

Wherein, when obtaining the voltage signal of ambient light, control pixel unit receives ambient light, and photodiode PD will Ambient light is converted to voltage signal, and control first switch is opened and control second switch is closed, and first voltage signal exports mould Block output first voltage signal is the voltage signal for indicating ambient light, when obtaining the voltage signal of reflected light of testee, Control pixel unit and receive reflected light, photodiode PD converts the reflected light into voltage signal, control first switch close with And control second switch is opened, second voltage signal output module output second voltage signal is the voltage letter for indicating reflected light Number, the second voltage for comparing the first voltage signal for indicating ambient light and indicating reflected light is believed to obtain proportionality coefficient, when obtaining When getting the voltage signal of reflected light, reflection photoelectric signal virtual value can be obtained in conjunction with proportionality coefficient.

Embodiment seven：

1 is please referred to Fig.1, the application proposes that a kind of depth information measuring method, method include：

Step S701：Voltage signal and the expression of the expression ambient light under current environment are obtained by above-mentioned pixel unit The proportionality coefficient of the reflection photoelectric signal of testee；

Step S702：System opens laser emitting source, and it is T to emit the time span through ovennodulation every time₀Laser pulse, The first switch for controlling the first voltage signal output module of pixel unit open and second voltage signal output module the Two switches are closed, and are obtained the first voltage signal obtained after light emitting diode transmitting photo-signal, are converted first voltage signal to First digital signal is converted to the virtual value of the first digital signal by the first digital signal according to proportionality coefficient according to setting means U₀；

Step S703：The first switch for controlling the first voltage signal output module of pixel unit is closed and second voltage The second switch of signal output module is opened, the second voltage signal obtained after acquisition light emitting diode transmitting photo-signal, and second Voltage signal is converted into the second digital signal, and the second digital signal is converted to the second number according to proportionality coefficient according to setting means The virtual value U of word signal₁；

Step S704：Gate the virtual value U of simultaneously the first digital signal of output pixel unit₀And second digital signal Virtual value U₁；

Step S705：According to formula：The corresponding testee of each pixel unit is calculated Range information L is also both depth information, wherein c is the light velocity.

Further, further include step before step S701：Control open pixel unit first release transistor with And second release transistor by pixel unit during idle time because ambient light generate stored charge discharge.

Pixel unit in the present embodiment please refers to pixel unit described in above example two, embodiment three, in this way No longer describe.

The advantageous effect of the application is：By the way that first voltage signal output module and the output of second voltage signal is arranged Module, the first switch of control first voltage signal output module and the second switch of second voltage signal output module are beaten On or off is closed, and output indicates that the first voltage signal of ambient light and output indicate the second voltage signal of reflected light, The virtual value that the voltage signal for indicating reflected light can be obtained according to the first voltage signal and second voltage signal, with this voltage The virtual value of signal is used as the measuring and calculating of depth information, improves the accuracy of the measurement of the depth information of testee, Neng Goushi For more complex environment so that more extensive using the application range of products of the technology.

It will be understood by those skilled in the art that all or part of step of various methods can pass through in the above embodiment Program instructs related hardware to complete, which can be stored in a computer readable storage medium, storage medium can wrap It includes：Read-only memory, random access memory, disk or CD etc..

The foregoing is a further detailed description of the present application in conjunction with specific implementation manners, and it cannot be said that this Shen Specific implementation please is confined to these explanations.For those of ordinary skill in the art to which this application belongs, it is not taking off Under the premise of conceiving from the present application, a number of simple deductions or replacements can also be made.

Claims

1. a kind of pixel unit, which is characterized in that the pixel unit includes：

Substrate；

Photodiode is set in the substrate, to the optical signal conversion that will be incident on the photodiode For voltage signal；

First voltage signal output module is used to be incident on the light conversion first voltage signal of the photodiode, Including first switch, the input terminal of the first switch connects the photodiode, when the first switch is opened, described the The exportable first voltage signal of output end of one switch；And

Second voltage signal output module is used for acquisition and is incident on the light output of the photodiode as second voltage letter Number comprising the input terminal of second switch, the second switch connects the photodiode, when the second switch is opened, The exportable second voltage signal of output end of the second switch；

Wherein, it when obtaining the voltage signal of ambient light, controls the pixel unit and receives the ambient light, two pole of the photoelectricity The ambient light is converted to voltage signal by pipe, is controlled the first switch and is opened and control the second switch closing, institute It is the voltage signal for indicating the ambient light to state first voltage signal output module and export the first voltage signal, when acquisition quilt It when surveying the voltage signal of the reflected light of object, controls the pixel unit and receives the reflected light, the photodiode is by institute It states reflected light and is converted to voltage signal, control the first switch closing and control the second switch and open, described second It is the voltage signal for indicating the reflected light that voltage signal output module, which exports the second voltage signal, compares and indicates the ring The first voltage signal of border light and the second voltage of the expression reflected light are believed to obtain proportionality coefficient, described anti-when to obtain When penetrating the effective voltage signal of light, the reflection photoelectric signal virtual value can be obtained in conjunction with the proportionality coefficient.

2. pixel unit as described in claim 1, which is characterized in that the photodiode is set to the center of the substrate The first switch of position, the first voltage signal output module is the first transmission transistor, and the first transmission transistor is set to In the substrate and be set to the side of the photodiode, the first transmission transistor and the photodiode-couple with The second switch of the voltage signal output that the photodiode is accumulated, the second voltage signal output module is the second biography Defeated transistor, second transmission transistor is set in the substrate and symmetrical first transmission transistor is set to institute The other side of photodiode is stated, the second transmission transistor is with the photodiode-couple to accumulate the photodiode Voltage signal output.

3. pixel unit as claimed in claim 2, which is characterized in that

The first voltage signal output module further includes：

First floating diffusion region is set in the substrate and is set to first transmission transistor far from the photoelectricity The side of diode, wherein the first voltage signal of the photodiode is transferred to described by first transmission transistor First floating diffusion region is preserved；

First reset transistor is set to the coupling photodiode in the substrate, expands described first to float The first voltage signal that area preserves is dissipated to be resetted；

First source following transistor, control terminal connect first floating diffusion region, and input terminal connection described first is multiple Bit transistor；And

First gating transistor, input terminal connect the output end of first source following transistor, and first gating is brilliant The output end of body pipe exports the first voltage signal；

The second voltage signal output module further includes：

Second floating diffusion region is set in the substrate and is set to second transmission transistor far from the photoelectricity The side of diode, wherein the second voltage signal of the photodiode is transferred to described by second transmission transistor Second floating diffusion region is preserved；

Second reset transistor is set on the substrate and couples the photodiode, expands described second to float The second voltage signal that area preserves is dissipated to be resetted；

Second source following transistor, control terminal connect second floating diffusion region, and input terminal connection described second is multiple Bit transistor；And

Second gating transistor, input terminal connect the output end of second source following transistor, and second gating is brilliant The output end of body pipe exports the second voltage signal.

4. pixel unit as claimed in claim 3, which is characterized in that

The first voltage signal output module further includes：First releases transistor, is set in the substrate and connects institute Photodiode is stated, is used for when the pixel unit is in idle condition, the photodiode is received into the environment Voltage signal caused by light discharges；

The second voltage signal output module further includes：Second releases transistor, is set in the substrate and connects institute Photodiode is stated, is used for when the pixel unit to be in idle condition, the photodiode is received into the ring Voltage signal discharges caused by the light of border；

Wherein, it before calculating and obtaining the reflected light virtual value, is released by opening described first and transistor and second is released Transistor is by the pixel unit during idle time because the stored charge that the ambient light generates discharges.

5. pixel unit as claimed in claim 4, which is characterized in that the photodiode is square and is set to described The center of substrate, first transmission transistor are set to the left side of the photodiode, first floating diffusion Area is set to the side of first transmission transistor far from the photodiode, and second transmission transistor is symmetrically described First transmission transistor is set to the right side of the photodiode, and second floating diffusion region symmetrical described first, which is floated, to be expanded Scattered area is set to the side of second transmission transistor far from the photodiode, and the described first transistor of releasing is set to The upside of the photodiode, the described second transistor of releasing of transistor symmetrical described first of releasing are set to the photoelectricity two The downside of pole pipe.

6. pixel unit as described in claim 1, which is characterized in that the photodiode is calendering electric diode.

7. a kind of image sensor chip, which is characterized in that described image sensor chip includes：

Pel array comprising multiple pixel units as described in claim 1, the pixel unit output voltage signal；

Bias unit is used to provide bias voltage for described image sensor chip；

AD conversion unit, the voltage signal for exporting the pixel unit are converted to digital signal, connect the picture Plain unit；

Scanning element, the digital signal for gating and exporting the pel array connect the pel array；

Control unit, connect and control the pel array, AD conversion unit, scanning element and bias unit work with It obtains and exports the digital signal；

Depth information computing unit is used to carry out operation according to the digital signal that the pixel unit exports to obtain testee Range information, connect described control unit；

Output unit is used to, by the distance information transmission to next stage application layer, connect the depth information and calculate list Member；

Wherein, system opens laser emitting source, and it is T to emit the time span through ovennodulation every time₀Laser pulse, the control Unit controls first switch opening and the output of second voltage signal of the first voltage signal output module of the pixel unit The second switch of module is closed, and the first voltage signal output module exports the first voltage signal, the analog-to-digital conversion Unit converts the first voltage signal to the first digital signal, presses first digital signal in conjunction with the proportionality coefficient The virtual value U of first digital signal is converted to according to setting means₀, described control unit controls the first of the pixel unit The first switch of voltage signal output module is closed and the second switch of second voltage signal output module is opened, and described second Voltage signal output module exports the second voltage signal, and the AD conversion unit converts the second voltage signal to Second digital signal is converted to second number by the second digital signal in conjunction with the proportionality coefficient according to setting means The virtual value U of signal₁；

The scanning element gates and exports the virtual value U of the first digital signal of the pixel unit₀And second digital signal Virtual value U₁, the depth information computing unit is according to formula：Each pixel can be calculated The range information L of the corresponding testee of unit is also both the depth information of testee, wherein c is the light velocity.

8. image sensor chip as claimed in claim 7, which is characterized in that the AD conversion unit includes that correspondence is adjacent Two pixel units settings correlated double sampling circuit, the correlated double sampling circuit includes：

The positive input input bias unit of the first operational amplifier and its peripheral circuit, first operational amplifier carries The negative input of the biasing voltage signal of confession, first operational amplifier passes through the two adjacent pictures of the first capacitance connection First gating transistor of plain unit, it is in parallel between the negative input and output end of first operational amplifier to be equipped with third Switch and the second capacitance, between the negative input and output end of first operational amplifier it is in parallel be equipped with the 4th switch with And third capacitance, it is in parallel between the negative input and output end of first operational amplifier to be equipped with the 5th switch, described the The negative input of one operational amplifier receives the first voltage signal of two pixel units, first operational amplifier Output end exports first digital signal；

The positive input input bias unit of second operational amplifier and its peripheral circuit, the second operational amplifier carries The negative input of the biasing voltage signal of confession, the second operational amplifier passes through the two adjacent pictures of the 4th capacitance connection Second gating transistor of plain unit, it is in parallel between the negative input and output end of the second operational amplifier to be equipped with the 6th Switch and the 5th capacitance, between the negative input and output end of the second operational amplifier it is in parallel be equipped with the 7th switch with And the 6th capacitance, it is in parallel between the negative input and output end of the second operational amplifier to be equipped with the 8th switch, described the The negative input of two operational amplifiers receives the second voltage signal of two pixel units, the second operational amplifier Output end exports second digital signal.

9. image sensor chip as claimed in claim 7, which is characterized in that the photodiode is set to the substrate Center, the first switch of the first voltage signal output module is the first transmission transistor, the first transmission transistor It is set in the substrate and is set to the side of the photodiode, the first transmission transistor and the photodiode Coupling is exported with the voltage signal for accumulating the photodiode, and the second switch of the second voltage signal output module is Second transmission transistor, second transmission transistor is set in the substrate and symmetrical first transmission transistor is set It is placed in the other side of the photodiode, the second transmission transistor and the photodiode-couple are with by two pole of the photoelectricity The voltage signal output of pipe accumulation.

10. a kind of imaging system, which is characterized in that it includes the imaging sensor core as described in claim 7 to 9 any one Piece and laser emitter.