CN112859092A

CN112859092A - Light emitting bare chip, emission module, sensing device and electronic equipment

Info

Publication number: CN112859092A
Application number: CN202110169379.9A
Authority: CN
Inventors: 王小明; 吕晨晋; 李佳鹏
Original assignee: Shenzhen Fushi Technology Co Ltd
Current assignee: Shenzhen Fushi Technology Co Ltd
Priority date: 2021-02-07
Filing date: 2021-02-07
Publication date: 2021-05-28

Abstract

The application provides a light emitting bare chip, an emission module, a sensing device and an electronic device. The light emitting die includes: a sensing light source for emitting a sensing light pulse for irradiating an external object to sense related information; a single photon avalanche diode connected in series with the sensing light source; the excitation circuit is used for emitting an excitation light beam which is used for triggering the single photon avalanche diode to generate avalanche, and the sensing light source is used for emitting the sensing light pulse after the single photon avalanche diode generates avalanche. The emission module, the sensing device and the electronic equipment comprise the light emitting bare chip.

Description

Light emitting bare chip, emission module, sensing device and electronic equipment

Technical Field

The present application relates to the field of photoelectric sensing technology, and more particularly, to a transmission module in a time-of-flight device, and an electronic apparatus.

Background

A Time of Flight (TOF) apparatus calculates a distance, or depth, of an object by measuring a Time of Flight of a light pulse in a space, and is widely used in the fields of consumer electronics, unmanned driving, AR/VR, etc. due to its advantages of long sensing distance, large measuring range, etc.

The TOF device comprises a transmitting module and a receiving module. The emitting module is used for emitting light pulses to a target space to provide illumination. The receiving module is used for receiving the light pulse returned from the external object and calculating the distance of the object according to the time required by the light pulse from emission to reception.

However, the sensing accuracy of the existing TOF apparatus is low, and the requirement of a scene with higher accuracy cannot be met.

Disclosure of Invention

The present embodiments are directed to solving at least one of the problems in the prior art. For this reason, the embodiments of the present application need to provide a light emitting die, an emission module, a sensing device and an electronic apparatus.

First, the present application provides a light emitting die comprising:

a sensing light source for emitting a sensing light pulse for irradiating an external object to sense related information;

a single photon avalanche diode connected in series with the sensing light source; and

the excitation circuit is used for emitting an excitation light beam which is used for triggering the single photon avalanche diode to generate avalanche, and the sensing light source is used for emitting the sensing light pulse after the single photon avalanche diode generates avalanche.

In some embodiments, the light emitting die further comprises a first switch connected between a first power supply and a first node, the series branch of the sensing light source and the single photon avalanche diode being connected between the first node and ground, and an energy storage capacitor being further connected between the first node and ground, the energy storage capacitor being integrated in the light emitting die or being disposed outside the light emitting die; the energy storage capacitor is used for receiving a power supply voltage from the first power supply through the first switch for pre-charging and biasing reverse pinch voltages at two ends of the single photon avalanche diode to a preset avalanche voltage, wherein the preset avalanche voltage is greater than or equal to a critical avalanche voltage, and the critical avalanche voltage is a minimum reverse voltage value when the single photon avalanche diode can generate avalanche; the energy storage capacitor is also used for discharging to the series branch when the single photon avalanche diode generates avalanche, and the sensing light source emits the sensing light pulse.

In some embodiments, the first switch is in an open state during avalanche of the single photon avalanche diode.

In some embodiments, the timing of the operation of the first switch is controlled by a control unit, which is integrated in the light emitting die or is disposed outside the light emitting die.

In some embodiments, when the control unit controls the first switch to be closed, the first power supply charges the energy storage capacitor through the first switch, and when the reverse voltage across the single photon avalanche diode reaches the preset avalanche voltage, the control unit controls the first switch to be opened.

In some embodiments, the predetermined avalanche voltage is greater than the critical avalanche voltage, and the voltage difference is in a range from 5 volts to 10 volts.

In some embodiments, the excitation circuit includes an excitation light source and a second switch; the excitation light source and the second switch are connected in series between a second power supply and the ground, or the excitation light source and the second switch are connected in series between a second node and the ground, and the second node is further connected with the first power supply and the first switch respectively; the excitation light source emits the excitation light beam through the conducted second switch.

In some embodiments, the control unit is further configured to control an operation timing of the second switch.

In some embodiments, when the single photon avalanche diode is required to generate avalanche, the control unit controls the second switch to be conducted, and the excitation circuit emits the excitation light beam to trigger the single photon avalanche diode to generate avalanche.

In some embodiments, the sensing light source stops emitting sensing light pulses when the energy storage capacitor discharges to a point where the reverse pinch voltage across the single photon avalanche diode is less than the critical avalanche voltage; alternatively, the sensing light source stops emitting the sensing light pulse when the current flowing through the sensing light source is less than a threshold current at which the sensing light source is capable of emitting light.

In some embodiments, the single photon avalanche diode is connected between the first switch and the sensing light source, or the sensing light source is connected between the first switch and the single photon avalanche diode.

In some embodiments, the sensing light pulse is used for sensing depth information or/and proximity information of an external object.

In some embodiments, a series branch of the single photon avalanche diode and the sensing light source comprises a plurality of the sensing light sources connected in series.

In some embodiments, the sensing light source and/or the excitation light source is a vertical cavity surface laser emitter, and the excitation light source is on the same side as the light emitting side of the sensing light source.

In some embodiments, the light emitting die is a light emitting die in a transmitting module in a time-of-flight apparatus for transmitting a sensing light pulse to an external object, and the receiving module in the time-of-flight apparatus is for receiving the sensing light pulse returned by the external object to obtain related sensing information of the external object.

The present application further provides a transmission module comprising the light emitting die of any one of the above.

In some embodiments, the emitting module further includes a modulating element disposed in the light emitting direction of the light emitting die for modulating the sensing light pulse emitted from the light emitting die.

In some embodiments, the modulation element includes a light homogenizing sheet for homogenizing the light beam emitted from the light emitting die to form a flood light beam; or, the modulation element comprises an optical diffraction element for performing replication and expansion on the light beam emitted by the light emitting die to form a speckle pattern.

In some embodiments, the emission module further comprises a light guide element disposed between the light emitting die and the modulation element, the light guide element for transmitting the excitation light beam onto the single photon avalanche diode.

The present application further provides a sensing device, which includes an emitting module and a receiving module, where the emitting module is configured to emit a sensing light pulse to an external object, and the receiving module is configured to receive the sensing light pulse returned by the external object and convert the received sensing light pulse into a corresponding electrical signal, so as to obtain sensing information related to the external object, where the emitting module is any one of the emitting modules described above.

In some embodiments, the sensing device is a direct time-of-flight device for sensing depth information or/and proximity information of an external object.

The present application further provides an electronic device comprising the sensing apparatus of any one of the above.

In this application the sensing light source, single photon avalanche diode and excitation circuit integrate at same luminous bare chip to can reduce the adverse effect of parasitic capacitance, parasitic resistance, parasitic inductance etc. in addition, because single photon avalanche diode can take place the avalanche as long as receive a photon, and response speed is very fast, and has advantages such as the internal resistance is very little of leading to, consequently, the pulse width of the sensing light pulse that the sensing light source sent can be narrower, thereby can improve sensing accuracy. Accordingly, the emission module, the sensing device and the electronic equipment comprising the light emitting die have high sensing precision.

Drawings

Fig. 1 shows a schematic structural diagram of a sensing device of an embodiment of the present application.

Fig. 2 is a schematic diagram of a partial circuit structure of a light emitting unit according to a first embodiment of the present application.

Fig. 3 is a schematic diagram of a partial circuit structure of a light emitting unit according to a second embodiment of the present application.

Fig. 4 is a schematic diagram of a partial circuit structure of a light emitting unit according to still another modified embodiment of the present application.

Fig. 5 is a block diagram of a light emitting unit according to a third embodiment of the present application.

Fig. 6 is a schematic diagram of a partial circuit structure of a light emitting unit according to still another modified embodiment of the present application.

Fig. 7 is a schematic diagram of a partial circuit structure of a light-emitting unit according to still another modified embodiment of the present application.

Fig. 8 is a schematic top view of a light emitting unit according to a fourth embodiment of the present application.

Fig. 9 is a schematic sectional view along the section line IX-IX' of fig. 8.

Fig. 10 is a schematic top view of a light emitting unit according to a fifth embodiment of the present application.

Fig. 11 is a schematic cross-sectional view of fig. 10 along section line XI-XI'.

Fig. 12 is a schematic top view of a light emitting unit according to a sixth embodiment of the present application.

FIG. 13 is a schematic cross-sectional view of FIG. 12 taken along section line XIII-XIII'.

Fig. 14 is a block diagram of an electronic device according to an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that: 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. Further, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

In the description of the present application, it is to be understood that the terms "first", "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicit indicating the number of technical features indicated. Thus, a feature defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.

In the following description, numerous specific details are provided to provide a thorough understanding of embodiments of the application. One skilled in the relevant art will recognize, however, that the subject technology can be practiced without one or more of the specific details, or with other structures, components, and so forth. In other instances, well-known structures or operations are not shown or described in detail to avoid obscuring the focus of the application.

It should be noted that, in the present application, a Single Die refers to a product that is cut from a Wafer (Wafer) without being packaged. A Chip (Single Chip) refers to a product in which one or more dies (Die) are packaged. In addition, a Node in this application refers to a connection point of two or more branches.

Through a great deal of creative work research and analysis, the inventor finds that the narrower the pulse width of the sensing light pulse emitted to the external space by the emitting module, the higher the detection accuracy of the depth information. The narrower the pulse width, the faster the rise time and fall time of the driving current for driving the sensing light source in the emission module. However, the electronic components in the driving circuit for generating the driving current in the emission module and the sensing light source are all discrete components and are electrically connected through wires and the like, so that a large parasitic inductance, a parasitic capacitance, a parasitic resistance and the like are inevitable to exist. Therefore, how to implement a sensing optical pulse with a narrow pulse width is a technical problem to be solved.

The inventors have further studied, through extensive and inventive work research and analysis, ways to solve the above technical problems from at least four main aspects as follows, individually or in combination.

Firstly, designing a new driving circuit;

secondly, selecting a new electronic component;

thirdly, integrating a plurality of electronic components in the same bare chip in a component integration mode;

fourthly, integrating a plurality of electronic components in two bare chips in a component integration mode, and electrically connecting the two bare chips in a vertical stacking mode;

any one or combination of the above modes can reduce parasitic inductance, parasitic resistance, and the like in an electronic circuit where the sensing light source is located, so that the pulse width of the sensing light pulse can be reduced, and the purpose of improving the sensing precision is achieved.

The four main aspects are explained in detail below with different embodiments.

Referring to fig. 1, fig. 1 is a schematic structural diagram of a sensing device according to an embodiment of the present disclosure. The sensing device 10 is configured to emit a sensing light pulse to an external object, receive the sensing light pulse returned by the external object, and convert the sensing light pulse into a corresponding electrical signal, which is used to obtain corresponding sensing information. For example, but not limited to, the electrical signal is used to obtain one or more of proximity information, depth information, or distance information of an external object. The depth information is used in the fields of 3D modeling, face recognition, automatic driving, instant positioning and mapping (SLAM), and the like, for example, and the present application does not limit this. The proximity information is used, for example, to determine whether or not an object is in proximity.

Optionally, the sensing device 10 is, for example, a TOF device. However, the sensing device 10 may also be other suitable types of devices for sensing proximity information or/and depth information, and even other suitable information, which is not limited in this application.

Alternatively, the TOF device is, for example, a Direct Time Of Flight (D-TOF) device. The D-TOF apparatus is based on the direct time-of-flight detection principle to perform depth information sensing. The D-TOF device obtains depth information of the external object by directly calculating a time difference between the sensing light pulse transmitted by the transmitting module and the sensing light pulse received by the receiving module. Alternatively, however, the TOF device may also be an Indirect Time Of Flight (I-TOF) device, for example. The I-TOF apparatus performs depth information sensing based on indirect time-of-flight detection principles. The I-TOF device obtains depth information of the external object by calculating a phase difference between the sensing light pulse transmitted by the transmitting module and the sensing light pulse received by the receiving module.

In the following embodiments of the present application, the sensing device 10 is mainly exemplified as a D-TOF device. It will be appreciated that the teachings of the present application can be extended to other suitable types of sensing devices 10.

Specifically, as shown in fig. 1, the sensing device 10 includes a transmitting module 11, a receiving module 12, and a processing module 13. The emitting module 11 is configured to emit a sensing light pulse 201 to a space of the external object 20, where at least a portion of the emitted sensing light pulse 201 returns from the external object 20 to form a sensing light pulse 202, and at least a portion of the sensing light pulse 202 is received by the receiving module 12. The returned sensing light pulse 202 carries depth information (or depth information) of the external object 20, for example.

The transmission module 11 includes: a light emitting unit 110 and a modulation element 112. The light emitting unit 110 is used for emitting a sensing light pulse. The modulation element 112 is configured to modulate the sensing light pulse emitted by the light emitting unit 110 to form a sensing light pulse 201 required for sensing, and to project the sensing light pulse 201 to the external object 20. Optionally, the sensing light pulse 201 emitted by the emitting module 11 is, for example and without limitation, a speckle pattern or a flood light beam.

Optionally, in some embodiments, the modulating element 112 is, for example, a diffusion sheet (Diffuser) or a light-homogenizing sheet, and is configured to homogenize the sensing light pulses emitted by the light-emitting unit 110 to form a flood light beam.

Optionally, in other embodiments, the modulation element 112 is, for example, a Diffractive Optical Element (DOE) for performing replica expansion on the sensing Optical pulse emitted by the light emitting unit 110 to form a speckle pattern. The speckle patterns can be arranged regularly, or can be arranged irregularly or randomly.

The sensing light pulse emitted by the light emitting unit 110 is replicated by the DOE, and the sensing light pulse emitted to the external object 20 is composed of a plurality of replicated sensing light pulses, which is beneficial to enlarging the field angle of the sensing device 10 and the number of sensing light pulses, and improving the imaging effect.

Alternatively, in some embodiments, the modulating element 112 may also be other suitable light beam modulating elements, such as a micro lens array, and the like, which is not particularly limited in this application. Those skilled in the art can select the corresponding modulation element 112 to modulate the sensing light pulse according to actual needs to obtain the required sensing light pulse 201.

Alternatively, in some embodiments, the modulating element 112 may be omitted.

Optionally, in some embodiments, the emitting module 11 may further include other suitable elements, such as a lens unit, disposed between the light emitting unit 110 and the modulating element 112, and configured to collimate or converge the sensing light pulse emitted by the light emitting unit 110 and transmit the collimated or converged sensing light pulse to the modulating element 112.

It should be understood that the wavelength range of the sensing light pulse emitted by the light emitting unit 110 is not limited in particular in the embodiments of the present application, and may be, for example, infrared light, ultraviolet light, visible light, and the like.

In some embodiments, the light emitting unit 110 may include a single sensing light source 22 (see fig. 2) or a plurality of sensing light sources 22. The plurality of sensing light sources 22 may be, for example, a regularly arranged or irregularly arranged light source array. Taking the sensing light source 22 as a Vertical-Cavity Surface-Emitting Laser (VCSEL for short), the light Emitting unit 110 may include a semiconductor substrate and a VCSEL array die formed by a plurality of VCSEL light sources arranged on the semiconductor substrate.

Optionally, the sensing Light source 22 may be, for example, a Light Emitting Diode (LED), a VCSEL, a Laser Diode (LD), a Fabry Perot (FP) Laser, a Distributed Feedback (DFB) Laser, an Electro-absorption Modulated Laser (EML), and other forms of Light sources, which are not limited in this application.

In some embodiments, the receiving module 12 comprises an image sensor. The image sensor includes, for example, a pixel array 120 composed of a plurality of pixel units, and the pixel array 120 is configured to receive a sensing light pulse 202 returned from the external object 20 to acquire relevant sensing information, such as, but not limited to, acquiring depth information of the external object 20.

In the present embodiment, a single pixel unit receives the sensing light pulse 202 for obtaining a depth information of the external object 20. In some embodiments, the single pixel cell may include a pixel, such as a single photon avalanche photodiode (SPAD) or other suitable photoelectric conversion element, and in other embodiments, the single pixel cell includes a plurality of pixels, such as an array pixel that may be made up of a plurality of SPADs.

Optionally, the receiving module 12 further includes a readout circuit formed by one or more of a signal amplifier, a time-to-digital converter (TDC), an analog-to-digital converter (ADC), and the like, which are connected to the image sensor, and the application is not limited thereto. Alternatively, part or all of the readout circuitry may also be integrated in the image sensor.

Optionally, the receiving module 12 further includes a lens unit 121, configured to receive the sensing light pulse 202 returned from the external object 20, and collimate or converge the sensing light pulse 202 before transmitting the sensing light pulse to the plurality of pixel units.

The processing module 13 is for example configured to determine depth information of the external object 20 according to a time difference between the sensing light pulse 201 and the sensing light pulse 202, so as to enable a depth imaging function of the sensing device 10 on the external object 20. However, alternatively, in other embodiments, the processing module 13 may also obtain the relevant sensing information according to the sensing light pulse 202 and based on other suitable detection principles, and is not limited to determining the relevant sensing information according to the time difference between the sensing light pulse 201 and the sensing light pulse 202.

Optionally, the processing module 13 may be a processing module of the sensing apparatus 10, or may also be a processing module of an electronic device including the sensing apparatus 10, for example, a main control module of the electronic device, which is not limited in this embodiment of the application.

Referring to fig. 2, fig. 2 is a schematic circuit diagram of a portion of a light emitting unit 110 according to a first embodiment of the present application. The light emitting unit 110 includes a driving circuit 20 and the sensing light source 22. The driving circuit 20 is electrically connected to the sensing light source 22, and is configured to drive the sensing light source 22 to emit the sensing light pulse. In fig. 2, the driving circuit 20 drives one sensing light source 22 to emit a sensing light pulse for example.

Optionally, the driving circuit 20 includes a first switch 21, a switching tube 23, an energy storage capacitor 25, and a control unit 27. The first switch 21 is connected between the first power supply 14 and the first node N1. The switch tube 23 and the sensing light source 22 are connected in series between the first node N1 and ground. The energy storage capacitor 25 is connected between the first node N1 and ground.

The control unit 27 is used for controlling the conduction of the first switch 21 and the switch tube 23. The energy storage capacitor 23 is configured to receive the voltage from the first power supply 14 through the turned-on first switch 21 to store energy. When the switch tube 23 is turned on, the energy storage capacitor 23 discharges the sensing light source 22 to provide electric energy for the sensing light source 22 to emit the sensing light pulse.

Optionally, the first switch 21 is in an off state during the period that the switching tube 23 is turned on. Further optionally, the first switch 21 and the switch tube 23 are turned on in a time-sharing manner.

In the present embodiment, the operation principle of the driving circuit 20 driving the sensing light source 22 to emit light is as follows.

The control unit 27 first controls the first switch 21 to be turned on, and the voltage of the first power supply 14 is pre-charged to the energy storage capacitor 25 through the turned-on first switch 21. After the energy storage capacitor 25 is charged, the control unit 27 controls the first switch 21 to be turned off. When the sensing light source 22 is required to emit the sensing light pulse, the control unit 27 controls the switching tube 23 to be turned on, the energy storage capacitor 25 discharges the sensing light source 22, and the sensing light source 22 emits the sensing light pulse. When the power on the energy storage capacitor 25 drops to a certain value, the sensing light source 22 stops emitting sensing light pulses. For example, when the power on the energy storage capacitor 25 drops to a level where the driving current generated in the driving circuit 20 is less than the threshold current for the sensing light source 22 to operate, the sensing light source 22 stops emitting the sensing light pulse.

In the present embodiment, the switch 23 is a transistor switch having at least three terminals, such as a metal-oxide semiconductor field effect transistor (as shown in fig. 2), a bipolar junction transistor, or other conventional switch. However, the switch tube 23 may be other suitable transistor switches having at least three terminals, such as a gallium arsenide transistor or a gallium nitride transistor with a fast response speed.

In this embodiment, since the first switch 21 is additionally disposed between the first power supply 14 and the sensing light source 22, and the first switch 21 is turned off during the driving of the sensing light source 22 by the driving circuit 20, parasitic inductance, parasitic resistance, parasitic capacitance, and the like on a long connecting wire between the first power supply 14 and the sensing light source 22 are not included in the driving circuit 20 when the sensing light source 22 emits light, so that adverse effects on the driving current generated by the driving circuit 20 can be reduced, and the rising speed and the falling speed of the driving current can be increased.

Further, in this embodiment, the energy storage capacitor 25 is additionally added, the energy storage capacitor 25 is used to provide electric energy to the sensing light source 22 for light emission, and as the energy storage capacitor 25 discharges continuously, the driving current first rises to a certain maximum current value and then drops continuously, so that when the electric energy on the energy storage capacitor 25 drops to the certain value, the sensing light source 22 stops light emission. Compared with the mode of controlling the switching-off of the switching tube by using the control unit to control the switching-off of the driving current in the prior art, the falling speed of the driving current is increased by discharging the energy storage capacitor 25 in the embodiment of the present application, so that the sensing light pulse can be narrowed, and the sensing precision of the sensing device 10 can be improved.

As can be seen from the above analysis, compared to the conventional method of controlling whether the driving circuit generates the driving current by controlling the conduction of the conventional switching tube through the control unit, the rising speed and the falling speed of the driving current generated by the driving circuit 20 according to the above embodiment of the present application are faster, so that it can be determined according to the circuit principle that the pulse width of the driving current becomes narrower and the rising amplitude of the driving current becomes larger, and further, the pulse width of the sensing light pulse emitted by the sensing light source 22 under the driving of the driving current becomes narrower and the pulse amplitude can become larger. Accordingly, the accuracy of the sensing information of the sensing module 10 can be improved.

For example, but not by way of limitation, when the processing module 13 obtains a depth map according to the electrical signal output by the receiving module 12, it is easier to find the peak information with the largest number of photons, so that the obtained depth information is accurate, and the sensing accuracy is improved.

Typically, the switch tube 23 is connected in parallel with a plurality of the sensing light sources 22. However, through extensive research, the inventor finds that, because the currents in the parallel branches are added, the current after addition is larger, and thus, even though a new design is made for the driving circuit, since a plurality of sensing light sources 22 are connected in parallel, the current cannot be realized when a larger driving current is needed. The main reason for the foregoing is also due to the adverse effects of parasitic inductance, parasitic resistance, and the like. Therefore, the inventors of the present application further propose that a pulse width of the driving current can be reduced and a magnitude of the driving current can be increased by connecting a plurality of sensing light sources 22 in series and increasing the driving voltage.

For example, in fig. 2, as an alternative, the switching tube 23 is connected in series with a light source group, and the light source group includes a plurality of the sensing light sources 22 connected in series. Since a plurality of the sensing light sources 22 are connected in series, the driving current in series can be reduced relative to the driving current in parallel. Accordingly, this can be achieved when a larger drive current is required.

Further optionally, the light source group may further include a plurality of sensing light sources 22 connected in parallel. That is, there are both a plurality of sensing light sources 22 connected in series and a plurality of sensing light sources 22 connected in parallel in the light source group.

It is obvious to those skilled in the art that the driving circuit 20 can be configured appropriately according to the technical content described in the present application to achieve the required sensing accuracy.

Alternatively, in other embodiments, the operation principle of the driving circuit 20 may be different from that of the above-described embodiments. For example, but not limited to, the first switch 21 may be in a conducting state when the switch tube 23 is conducting.

One of the main improved technical solutions of the present application is: the circuit structure of the driving circuit 20 may be changed according to any suitable operation principle based on the circuit structure of the driving circuit 20 of the present application, and the changes and the operation principles are within the protection scope of the present application.

Optionally, the first power supply 14 is, for example, an external power supply, and certainly, may also be an internal power supply of the transmitting module 11, which is not limited in this application.

Optionally, the sensing light source 22 is connected between the first node N1 and the switch tube 23, and the switch tube 23 is further connected to ground. Alternatively, the switch tube 23 is connected between the first node N1 and the sensing light source 22, and the sensing light source 22 is further connected to the ground.

Through a great deal of creative work research and analysis, the inventor finds that the parasitic resistance and the parasitic capacitance of the metal-oxide semiconductor field effect transistor and the like serving as the switching tube 23 are large, the response speed is slow, and therefore the sensing device 10 is difficult to generate picosecond-level sensing light pulses. The inventor further found through extensive research and analysis that selecting an Avalanche type photodiode, especially, for example, a Single Photon Avalanche Diode (SPAD) as the switching tube 23 enables the sensing device 10 to generate picosecond-level sensing light pulses.

The avalanche photodiode in the present application refers to a phenomenon in which "avalanche" (i.e., a photocurrent is multiplied) occurs when a reverse bias voltage is applied to a PN junction of the photodiode, and thus is called an "avalanche photodiode".

Referring to fig. 3, fig. 3 is a schematic circuit diagram of a portion of a light emitting unit 110 according to a second embodiment of the present application. The main difference between the light emitting unit 110 of this embodiment and the light emitting unit 110 of the above-described embodiment is that: first, the switching tube 23 in the driving circuit 20 of the light emitting unit 110 of the embodiment is an avalanche type photodiode; second, the driving circuit 20 further includes an excitation circuit 28. For clarity and brevity, the same or similar parts of the light emitting unit 110 of the embodiment and the light emitting unit 110 of the first embodiment are not repeated herein.

The excitation circuit 28 is adapted to emit an excitation beam for triggering the avalanche mode photodiode to avalanche.

Optionally, the control unit 27 is configured to control an operation timing of the excitation circuit 28.

Optionally, the excitation circuit 28 includes an excitation light source 280 and a second switch 282. The excitation light source 280 is connected in series with the second switch 282. When the second switch 282 is turned on, the excitation light source 280 emits the excitation light beam. When the second switch 282 is open, the excitation light source 280 does not emit the excitation light beam.

The conduction or non-conduction of the second switch 282 is controlled by the control unit 27.

Alternatively, the second switch 282 may be, for example, but not limited to, a metal-oxide semiconductor field effect transistor (as shown in fig. 2), a conventional switching transistor such as a bipolar junction transistor, and the like.

Such as, but not limited to, vertical cavity surface emitting lasers VCSEL, LEDs, etc. The excitation light beam may be, for example, infrared light, ultraviolet light, visible light, etc., and the present application is not limited thereto.

Optionally, in this embodiment, the excitation light source 280 and the second switch 282 are connected in series between the second power supply 15 and the ground. The second power supply 15 may be an external power supply, or an internal power supply of the transmitting module 11, which is not limited in this application.

However, alternatively, in other embodiments, as shown in fig. 4, the excitation light source 280 and the second switch 282 may be connected in series between the second node N2 and the ground. The second node N2 is connected to the first power supply 14 and the first switch 21, respectively.

When the sensing light source 22 needs to emit light, the control unit 27 first controls the first switch 21 to be turned on, the first power supply 14 first pre-charges the energy storage capacitor 25 through the turned-on first switch 21, and after the energy storage capacitor 25 is charged, the control unit 27 controls the first switch 21 to be turned off. When the sensing light source 22 needs to emit light, the control unit 27 controls the second switch 282 to be turned on, and the excitation light source 280 emits an excitation light beam. The avalanche type photodiode receives the excitation light beam and avalanche occurs. The energy storage capacitor 25 discharges the sensing light source 22, triggering the sensing light source 22 to emit the sensing light pulse.

Wherein, when the energy storage capacitor 25 is charged, it can bias the reverse voltage across the avalanche type photodiode to a preset avalanche voltage, and the preset avalanche voltage is greater than or equal to the critical avalanche voltage of the avalanche type photodiode. The critical avalanche voltage is the minimum voltage value at which the avalanche type photodiode can avalanche.

The inventors have found through extensive and inventive research and analysis that the avalanche photodiode is preferably a single photon avalanche photodiode. The single photon avalanche diode can immediately generate avalanche as long as receiving one photon, and the response speed is very high. Moreover, the parasitic resistance, the parasitic capacitance and the like of the single photon avalanche diode during avalanche are very small, and the main part of the circuit loop where the sensing light source 22 is located is also the internal resistance of the sensing light source 22, so the design is good, the parasitic capacitance of the circuit loop is small, and the energy storage capacitor 25 can discharge very quickly, so that the sensing light source 22 can generate picosecond-level sensing light pulses.

The pulse width of the sensing light pulse emitted by the sensing light source 22 of the present embodiment may be less than 1 nanosecond. For example, but not limiting of, the pulse width of the sensing light pulse is, for example, but not limiting of, 800 picoseconds, 500 picoseconds, or even shorter.

In this embodiment, when the energy storage capacitor 25 is continuously discharged and the reverse voltage of the single photon avalanche type photodiode is smaller than the critical avalanche voltage, the driving circuit 20 stops generating the driving current. In this manner, the sensing light source 22 may also stop emitting sensing light pulses.

Alternatively, the critical avalanche is, for example, 15V. It can be seen that, to make the single photon avalanche type photodiode avalanche, the reverse voltage value is higher, and therefore, compared to the conventional way of turning off the switch tube by using the control unit in the prior art, the energy storage capacitor 25 is used to discharge in this embodiment, accordingly, the reverse voltage on the single photon avalanche type photodiode is continuously reduced and can be relatively quickly reduced below the critical avalanche voltage, so that the pulse width of the sensing light pulse emitted by the sensing light source 22 can be narrower.

In the example of fig. 3 and 4, only one single photon avalanche diode 23 is shown in series with the sensing light source 22 between the first node N1 and ground. However, alternatively, in other embodiments, a plurality of single photon avalanche diodes 23 connected in parallel may be connected in series with the sensing light source 22. Thus, the overall response speed of the switching tube 23 can be increased, and the drive current can be increased.

However, alternatively, in some embodiments, the Avalanche photodiode may be other suitable photodiodes, such as Avalanche Photodiode (APD). When the switch tube 23 is the avalanche photodiode, for example, a plurality of avalanche photodiodes are used in parallel, so that the response speed can be increased and the drive current can be increased.

Preferably, the preset avalanche voltage is greater than the critical avalanche voltage. More preferably, the pressure difference between the two ranges, for example, from 5 volts to 10 volts. However, alternatively, in other implementations, the voltage difference between the preset avalanche voltage and the critical avalanche voltage can be in other suitable ranges or values, which is not limited in the present application.

Normally, dark current causes the single photon avalanche diode to avalanche, and therefore this uncontrolled avalanche is reduced in order not to affect the sensing. Therefore, in practical products, the avalanche probability of the single photon avalanche diode caused by dark current is ensured to reach the millisecond level or more. Accordingly, in a 50 ns cycle, it is guaranteed that there is one uncontrolled avalanche for twenty thousand avalanches. In addition, fast charging can reduce uncontrolled avalanche. For example, when a single photon avalanche diode avalanche is required, the single photon avalanche diode is raised from below the critical avalanche voltage to a preset avalanche voltage within 4 nanoseconds, and then the second switch 282 is closed within 1 nanosecond to trigger the single photon avalanche diode avalanche. The whole process is finished in 5 ns, so that avalanche caused by dark current can be generated only in the 5 ns, and is reduced by one order of magnitude compared with the original 50 ns period.

In the embodiment shown in fig. 3, the single photon avalanche diode comprises a cathode P and an anode N, the anode N is connected to ground, the cathode P is connected to the sensing light source 22, and the sensing light source 22 is further connected to the first node N1. Alternatively, in other embodiments, the cathode P is connected to the first node N1, and the anode P is connected to the sensing light source 22. The sensing light source 22 is further connected to ground.

Optionally, the driving circuit 20 further includes a light guide element 29. The excitation light beam is conducted through the light guiding element 29 onto the avalanche type photodiode.

The light guiding element 29 may adjust the optical path of the excitation beam such that as much of the excitation beam as possible is received by the avalanche type photodiode, thereby ensuring that the avalanche type photodiode is immediately avalanche when avalanche is required.

The processing of the optical path of the excitation beam by the light guiding element 29 may be any optical processing, such as reflection, refraction, scattering, etc., as long as it is possible to guide enough excitation beam onto the avalanche type photodiode to ensure that the avalanche type photodiode can avalanche immediately when avalanche is needed.

The second main improvement technical scheme of this application lies in: the avalanche photodiode is selected as the switching tube 23 in the circuit structure of the driving circuit 20, and particularly, the single photon avalanche diode is selected as the switching tube 23, so that the driving circuit 20 can generate the driving current with a narrow pulse width and a large instantaneous power, and further, the sensing light source 22 is driven to generate the picosecond-level sensing light pulse, thereby greatly improving the sensing precision of the sensing device 10.

The inventor finds, through a great deal of research and analysis, that electronic components on a circuit board are generally connected through wires, and such wires generally have the characteristics of being long and the like, so that parasitic inductance and parasitic resistance in a circuit loop are large, and thus the influence on the rising speed and the falling speed of a driving current in the circuit loop is serious.

Referring to fig. 5, fig. 5 is a block diagram of a light emitting unit 110 according to a third embodiment of the present application. The same or similar parts of the light emitting unit 110 in this embodiment and the light emitting unit 110 in the first embodiment are not repeated herein, but the difference is mainly that the light emitting unit 110 includes or is a light emitting die.

The light emitting die includes the sensing light source 22 and the switch tube 23.

Since the sensing light source 22 and the switch tube 23 are integrated in the same light emitting die, the connecting wires between the sensing light source 22 and the switch tube 23 can be reduced, and thus the adverse effects of parasitic inductance, parasitic resistance and the like can be reduced, and accordingly, the sensing accuracy of the sensing device 10 can be improved.

Optionally, the first switch 21 and/or the energy storage capacitor 25 are integrated in the light emitting die, so that the connecting wires in the loop circuit where the sensing light source 22 is located can be further reduced, the adverse effects of parasitic inductance, parasitic resistance and the like can be further reduced, and accordingly, the sensing accuracy of the sensing device 10 can be further improved.

Optionally, the control unit 27 is integrated in the light emitting die, so that the sensing accuracy of the sensing device 10 can be further improved.

Since the driving circuit 20 and the electronic components such as the sensing light source 20 are integrated in the same light emitting die, the volume of the transmitting module 11 is smaller.

When the energy storage capacitor 25 is integrated in the light emitting die, the capacitance value of the energy storage capacitor 25 is, for example, but not limited to, 10 picofarads or more and less than 1 nanofarad. When the energy storage capacitor 25 is disposed outside the light emitting die, the capacitance of the energy storage capacitor 25 is, for example, 10 picofarads or more. Specifically, the capacitance value of the energy storage capacitor 25 is, for example, 500 picofarads. However, the capacitance of the energy storage capacitor 25 is not specifically limited in this application. Those skilled in the art can select the energy storage capacitor 25 with a corresponding capacitance according to the technical content and practical requirements described in the present application.

In the embodiment in which electronic components are integrated on the same light emitting die, the present application may also provide a light emitting unit 110 according to a modified embodiment as shown in fig. 6 and 7. Specifically, for the light emitting unit 110 of the embodiment shown in fig. 6, the control unit 27 controls whether the driving current is generated in the driving circuit 20 by controlling the conduction of the switching tube 23. Since the switching tube 23 and the sensing light source 22 are integrated in the same light emitting die, adverse effects of parasitic inductance and the like can be reduced to some extent, thereby improving the sensing accuracy of the sensing device 10. Optionally, the control unit 27 may also be integrated in the light emitting die. The driving circuit 20 in fig. 6 does not comprise said energy storing capacitor 25 and said first switch 21.

For the light emitting unit 110 of the modified embodiment shown in fig. 7, compared to the light emitting unit 110 of the embodiment shown in fig. 6, the driving circuit 20 of the light emitting unit 110 of the embodiment shown in fig. 7 further includes the energy storage capacitor 25. Thus, the energy storage capacitor 25 can immediately provide power to the sensing light source 22 to emit light when the switch tube 23 is turned on. The energy storage capacitor 25 is integrated in the light emitting die or arranged outside the light emitting die.

Referring to fig. 3, 8 and 9, fig. 8 is a schematic top view of a light emitting unit 110 according to a fourth embodiment of the present disclosure. Fig. 9 is a schematic sectional view along the section line IX-IX' of fig. 8. The same or similar parts of the light emitting unit 110 in this embodiment and the light emitting unit 110 in the second embodiment are not repeated herein, but the difference is mainly that the light emitting unit 110 includes or is a light emitting die.

Optionally, the light emitting unit 110 includes a light emitting die. The light emitting die includes the sensing light source 22 and the switch tube 23.

Optionally, part or all of the excitation circuit 28 is integrated in the light emitting die. When the excitation light source 280 is integrated in the light emitting die, the light emitting side of the excitation light source 280 and the light emitting side of the sensing light source 22 are located on the same side, for example.

For the light emitting unit 110 of this embodiment, since the driving circuit 20 includes the first switch S1, the energy storage capacitor 25, especially the single photon avalanche diode, and the driving circuit 20 and the electronic components such as the sensing light source 20 are integrated in the same light emitting die, the light emitting unit 110 of this embodiment can not only further reduce the adverse effects of parasitic inductance, parasitic resistance, etc., to a greater extent, and improve the sensing accuracy of the sensing device 10 to a greater extent, but also the volume of the emitting module 11 is smaller. The light emitting unit 110 of the present embodiment may generate a sensing light pulse with a narrower pulse width, for example, but not limited to, the pulse width of the sensing light pulse is 100 picoseconds, 200 picoseconds, 300 picoseconds, and the like.

Optionally, the light guide element 29 is located outside the light emitting die and is not integrated in the light emitting die. Alternatively, however, in some embodiments, the light guide element 29 may also be integrated inside the light emitting die.

In the present embodiment, the light guide element 29 is disposed above the light emitting side of the light emitting die and above between the excitation light source 280 and the switch tube 23. Optionally, the light guide element 29 includes a first opening (not shown) and a second opening 293 (not shown). The first opening 291 faces the light emitting direction of the excitation light source 280, and the second opening 293 faces the light receiving direction of the switch tube 23. Therefore, the excitation light beam emitted from the excitation light source 280 enters the light guide element 29 through the first opening 291, is transmitted from the inside of the light guide element 29, and is output to the switch tube 23 through the second opening 293.

Optionally, the light guide element 29 can block ambient light from being incident on the switch tube 23, so as to prevent the ambient light from causing avalanche of the switch tube 23.

The positional relationship of the electronic components in fig. 8 and 9 is merely an example, and other appropriate setting relationships may be used, and the positional relationship is not limited to the positional relationship of the electronic components shown in fig. 8 and 9.

The third main improvement technical scheme of the application is as follows: electronic components such as the sensing light source 22 and the switching tube 23 are integrated in the same die, so that adverse effects of parasitic inductance, parasitic resistance and the like can be reduced to a greater extent, and the purpose of further improving the sensing accuracy of the sensing device 10 is achieved.

Referring to fig. 2, fig. 10, and fig. 11, fig. 10 is a schematic top view of a light emitting unit 110 according to a fifth embodiment of the present disclosure. Fig. 11 is a schematic cross-sectional view of fig. 10 along section line XI-XI'. The light emitting unit 110 of this embodiment is the same as or similar to the light emitting unit 110 of the first embodiment, and is not repeated, and the main difference of the light emitting unit 110 of this embodiment is that the light emitting unit 110 includes a light emitting die 110A and a switch die 110B. The light emitting die 110A includes the sensing light source 22. The switch die 110B includes the switch tube 23.

The area of one side surface of the light emitting die 110A for emitting the sensing light pulse is defined as a light emitting area G, and the non-light emitting area is defined as a non-light emitting area F. Alternatively, the switch die 110B is disposed above the non-light-emitting region F, for example, between the non-light-emitting region F and the modulation element 112. Further optionally, the switch die 110B is flipped over the non-light emitting region F and is electrically connected to the light emitting die 110A vertically. For example and without limitation, the light emitting die 110A and the switch die 110B are electrically connected vertically, for example and without limitation, by metal bumps T. Accordingly, parasitic inductance, parasitic resistance, and the like can be reduced to some extent, thereby improving the sensing accuracy of the sensing device 10. The metal bump T is made of a conductive material with small internal resistance, such as gold or copper.

The first switch 21 and/or the energy storage capacitor 25 and/or the control unit 27 are integrated in the light emitting die 110A or the switch die 110B or are arranged outside the light emitting die 110A and the switch die 110B.

Preferably, the first switch 21 and/or the energy storage capacitor 25 and/or the control unit 27 are integrated in the switch die 110B.

The positional relationship of the electronic components in fig. 10 and 11 is merely an example, and other appropriate setting relationships may be used, and the positional relationship is not limited to the positional relationship of the electronic components shown in fig. 10 and 11.

Similarly, for the embodiments of fig. 6 and fig. 7, the technical idea of this implementation may also be adopted, and is not described herein again.

Referring to fig. 3, 12 and 13, fig. 12 is a schematic top view illustrating a light emitting unit 110 according to a sixth embodiment of the present disclosure. FIG. 13 is a schematic cross-sectional view of FIG. 12 taken along section line XIII-XIII'. The light emitting unit 110 of this embodiment is the same as or similar to the light emitting unit 110 of the second embodiment, and is not repeated, and the main difference of the light emitting unit 110 of this embodiment is that the light emitting unit 110 includes a light emitting die 110A and a switch die 110B. The light emitting die 110A includes the sensing light source 22 and the excitation light source 280. The switch die 110B includes a switch tube 23.

The area of the side surface of the light emitting die 110A for emitting the sensing light pulse is defined as a first light emitting area M1, the area of the side surface of the light emitting die 110A for emitting the excitation light beam is defined as a second light emitting area M2, and the first light emitting area M1 and the second light emitting area M2 are located on the same side.

Optionally, the switch die 110B is flipped over the second light emitting region M2 for receiving the excitation light beam emitted by the excitation light source 280. The switch die 110B and the light emitting die 110A are vertically connected, for example. Optionally, the switch die 110B and the light emitting die 110A are vertically connected up and down by a metal bump T, for example.

Optionally, the first switch 21 and/or the second switch 282 and/or the energy storage capacitor 25 and/or the control unit 27 are integrated in the light emitting die 110A or the switch die 110B or are disposed outside of both dies.

The light emitting unit 110 of the present embodiment can also reduce adverse effects of parasitic inductance and parasitic capacitance to some extent, and improve sensing accuracy.

The positional relationship of the electronic components in fig. 12 and 13 is merely an example, and other appropriate setting relationships may be used, and the positional relationship is not limited to the positional relationship of the electronic components shown in fig. 12 and 13.

In the above embodiments, the switch tube 23 may also be another suitable type of switch tube, which is not limited in this application.

Referring to fig. 14, fig. 14 is a block diagram of an electronic device according to an embodiment of the present disclosure. The electronic device 1 comprises the sensing arrangement 10. The electronic device 1 includes, for example, but not limited to, a smart phone, a tablet computer, a notebook computer, a desktop computer, a smart wearable device, a smart door lock, a vehicle-mounted electronic device, a medical device, an aviation device, and other devices or apparatuses requiring a 3D information sensing function.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A light emitting die, comprising:

a sensing light source for emitting a sensing light pulse for irradiating an external object to acquire depth information of the external object;

2. The light emitting die of claim 1, further comprising a first switch connected between a first power supply and a first node, the series branch of the sensing light source and the single photon avalanche diode being connected between the first node and ground, an energy storage capacitor also being connected between the first node and ground, the energy storage capacitor being integrated in the light emitting die or being disposed external to the light emitting die; the energy storage capacitor is used for receiving a power supply voltage from the first power supply through the first switch for pre-charging and biasing reverse pinch voltages at two ends of the single photon avalanche diode to a preset avalanche voltage, wherein the preset avalanche voltage is greater than or equal to a critical avalanche voltage, and the critical avalanche voltage is a minimum reverse voltage value when the single photon avalanche diode can generate avalanche; the energy storage capacitor is also used for discharging to the series branch when the single photon avalanche diode generates avalanche, and the sensing light source emits the sensing light pulse.

3. The light emitting die of claim 2, in which the first switch is in an open state during avalanche of the single photon avalanche diode.

4. The light emitting die of claim 3, wherein the timing of the operation of the first switch is controlled by a control unit integrated in the light emitting die or disposed external to the light emitting die.

5. The light emitting die of claim 4, wherein the first power supply charges the energy storage capacitor through the first switch when the control unit controls the first switch to be closed, and wherein the control unit controls the first switch to be open when a reverse voltage across the single photon avalanche diode reaches the preset avalanche voltage.

6. The light emitting die of claim 5, wherein the predetermined avalanche voltage is greater than the critical avalanche voltage and the voltage difference is in a range from 5 volts to 10 volts.

7. The light emitting die of claim 4, wherein the excitation circuit comprises an excitation light source and a second switch; the excitation light source and the second switch are connected in series between a second power supply and the ground, or the excitation light source and the second switch are connected in series between a second node and the ground, and the second node is further connected with the first power supply and the first switch respectively; the excitation light source emits the excitation light beam through the conducted second switch.

8. The light emitting die of claim 7, wherein the control unit is further configured to control an operation timing of the second switch.

9. The light emitting die of claim 8, wherein when the single photon avalanche diode is required to avalanche, the control unit controls the second switch to be turned on, and the excitation circuit emits the excitation beam to trigger the single photon avalanche diode to avalanche.

10. The light emitting die of claim 2, wherein the sensing light source stops emitting sensing light pulses when the energy storage capacitor discharges to a point where a reverse pinch voltage across the single photon avalanche diode is less than the critical avalanche voltage; alternatively, the sensing light source stops emitting the sensing light pulse when the current flowing through the sensing light source is less than a threshold current at which the sensing light source is capable of emitting light.

11. The light emitting die of claim 1, wherein the light emitting die is a light emitting die in a transmitting module in a time-of-flight apparatus for transmitting a sensing light pulse to an external object, and a receiving module in the time-of-flight apparatus for receiving the sensing light pulse returned by the external object to obtain related sensing information of the external object.