CN213210470U

CN213210470U - Emission module of time of flight TOF device

Info

Publication number: CN213210470U
Application number: CN202020797958.9U
Authority: CN
Inventors: 王小明
Original assignee: Shenzhen Fushi Technology Co Ltd
Current assignee: Shenzhen Fushi Technology Co Ltd
Priority date: 2020-05-14
Filing date: 2020-05-14
Publication date: 2021-05-14
Anticipated expiration: 2030-05-14

Abstract

The application provides a time of flight TOF device's transmission module includes: a light source for emitting a pulsed light beam; and a driving circuit connected to the light source for driving the light source to emit a pulse beam, the driving circuit including: the light source switch is connected with one end of the light source, the other end of the light source is connected with one end of the current-limiting resistor, the other end of the current-limiting resistor is connected with power voltage, the driving capacitor is connected with the current-limiting resistor in parallel, the light source switch is used for controlling the light source to be turned on and off, and the driving capacitor is used for improving the current value flowing through the light source when the light source switch is turned on so as to reduce the rising time of the rising edge of the pulse light beam emitted by the light source.

Description

Emission module of time of flight TOF device

Technical Field

The present application relates to the field of 3D technology, and more particularly, to a transmission module of a time of flight TOF apparatus, a time of flight TOF apparatus and an electronic device.

Background

The Time of Flight (TOF) module calculates the distance, or depth, of an object by measuring the Time of Flight of a light beam in space, and is widely applied to the fields of consumer electronics, unmanned driving, AR/VR, and the like due to its advantages of high precision, large measurement range, and the like.

The TOF module includes a light source for emitting a pulsed light beam to the target space to provide illumination and a camera for acquiring depth information or distance of the external object based on a time difference or a phase difference between the pulsed light beam returned from the external object and the pulsed light beam emitted from the light source to the target space.

The TOF module includes a D-TOF (direct Time Of flight) module and an I-TOF (index Time Of flight) module. The D-TOF module is used for acquiring depth information or distance of the external object according to a time difference between a pulse light beam returned from the external object and the pulse light beam emitted to the target space by the light source. The I-TOF module is used for acquiring depth information or distance of an external object according to a phase difference between a pulse light beam returned from the external object and a pulse light beam emitted to a target space by a light source.

The shorter the rise time of the pulsed light emitted to the target space by the light source, the higher the detection accuracy of the depth. However, the rising time of the rising edge of the pulsed light emitted by the conventional light source is long, which results in low sensing accuracy of the TOF module.

SUMMERY OF THE UTILITY MODEL

The application provides a time of flight TOF device's transmission module, time of flight TOF device and electronic equipment, can reduce the rise time of the rising edge of the light pulse of transmission module transmission.

A transmit module of a time-of-flight TOF apparatus in a first aspect, comprising:

a light source for emitting a pulsed light beam; and

a driving circuit connected to the light source for driving the light source to emit a pulse beam, the driving circuit comprising: the light source switch is connected with one end of the light source, the other end of the light source is connected with one end of the current-limiting resistor, the other end of the current-limiting resistor is connected with power voltage, the driving capacitor is connected with the current-limiting resistor in parallel, the light source switch is used for controlling the light source to be turned on and off, and the driving capacitor is used for improving the current value flowing through the light source when the light source switch is turned on so as to reduce the rising time of the rising edge of the pulse light beam emitted by the light source.

In some possible implementations, the driving circuit further includes:

and the power switch driving circuit is connected with the power switch and used for controlling the on and off of the power switch according to the driving signal.

In some possible implementations, the power switch driving circuit is specifically configured to:

when the driving signal is at a first level, controlling the light source switch to be conducted so as to enable the light source to emit a light beam; and

when the driving signal is at a second level, controlling the light source switch to be switched off so that the light source stops emitting a light beam;

wherein the first level is different from the second level.

In some possible implementations, the first level is a high level and the second level is a low level; or, the first level is a low level, and the second level is a high level.

In some possible implementations, the driving circuit further includes:

and one end of the filter capacitor is connected with the power supply voltage, and the other end of the filter capacitor is grounded.

In some possible implementations, the light source includes a plurality of sub light source groups, each sub light source group including at least one sub light source;

the time-of-flight TOF apparatus further comprises a receiving module, wherein the receiving module comprises a plurality of pixel units, and is configured to receive the pulse light beam returned from the external object in a time-sharing manner when the pulse light beam is emitted by the plurality of sub-light source components in the time-sharing manner, so as to obtain depth information of the external object.

In some possible implementations, the light source switch includes a plurality of control switches, each control switch being configured to control turning on and off of one of the plurality of sub light source groups.

In some possible implementations, the current-limiting resistor is connected to an anode of the light source, and a cathode of the light source is connected to the light source switch.

In some possible implementations, the light source is a VCSEL light source, and the pulsed light beam is a square wave signal.

In some possible implementations, the time of flight TOF device is a transmit module of an I-TOF device or a transmit module of a D-TOF device.

In a second aspect, there is provided a time-of-flight TOF apparatus, including the transmitting module and the receiving module in the first aspect or any possible implementation manner, where the transmitting module is configured to transmit a pulsed light beam and project the transmitted pulsed light beam to an external object, and the receiving module is configured to receive the pulsed light beam returned from the external object to obtain depth information of the external object.

In a third aspect, an electronic device is provided, including:

the time of flight TOF apparatus of the second aspect described above.

Because the drive capacitor connected with the current-limiting resistor in parallel is added in the drive circuit of the emission module of the TOF device, the current value flowing through the light source can be improved, and the rise time of the rising edge of the pulse light beam emitted by the light source is reduced. Therefore, the sensing accuracy of the TOF module can be improved. Correspondingly, the performance of the electronic equipment with the TOF module is better.

Drawings

Fig. 1 is a schematic configuration diagram of a time-of-flight TOF apparatus according to an embodiment of the present application.

Fig. 2 is a schematic diagram of a driving circuit structure of a light source of the TOF apparatus shown in fig. 1.

Fig. 3 is a schematic structural 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" and "first" are used merely for descriptive purposes and are not to be construed as indicating or implying relative importance or implying any indication of the number of technical features indicated. Thus, features 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.

Referring to fig. 1, fig. 1 shows a schematic block diagram Of a Time Of Flight (TOF) apparatus 10 according to an embodiment Of the present application. Alternatively, the TOF apparatus 10 can be adapted for mounting on an electronic device. Such as, but not limited to, smart phones, tablets, computers, laptops, desktop computers, smart wearable devices, smart door locks, in-vehicle electronics, medical, aerospace, and other devices or apparatuses with TOF functionality requirements.

The TOF device 10 may be a D-TOF device, an I-TOF device, or another suitable type of TOF device. This is not limited by the present application. The structure of the TOF apparatus 10D-TOF apparatus will be described as an example.

Specifically, as shown in fig. 1, the TOF apparatus 10 includes a transmitting module 11, a receiving module 12 and a processing module 13. The emitting module 11 is configured to emit a pulse light beam 201 to a space of the external object 20, at least a portion of the emitted pulse light beam 201 returns from the external object 20 to form a pulse light beam 202, the returned pulse light beam 202 carries depth information (or depth information) of the external object 20, at least a portion of the pulse light beam 202 is received by the receiving module 12, and the processing module 13 is configured to calculate a time difference or a phase difference between the light beam 201 and the light beam 202 to determine the depth information of the external object 20, so that a depth imaging function of the TOF apparatus 10 on the external object can be achieved. Optionally, the pulsed light beam is a square wave signal. Optionally, the depth information of the external object 20 in the embodiment of the present application may be used for 3D modeling, face recognition or simultaneous localization and mapping (SLAM), ranging, unmanned driving, AR/VR, and the like, for example, which is not limited in the present application.

Optionally, the processing module 13 is connected to the transmitting module 11 and the receiving module 12, and the processing module 13 is further configured to synchronize trigger signals of the transmitting module 11 and the receiving module 12 to calculate a time required for the pulsed light beam 201 to be emitted from the transmitting module 11 to be received by the receiving module 12, that is, a time difference or a phase difference between the emitted light beam 201 and the received light beam 202, so as to determine depth information of a corresponding point on the external object 20.

Optionally, the processing unit 13 may be a processing module of the TOF apparatus 10, and may also be a processing module of an electronic device including the TOF apparatus 10, for example, a main control module of the electronic device, which is not limited in this embodiment of the present disclosure.

The transmission module 11 includes: a light source 110 and a modulation element 111, wherein the light source 110 is configured to emit a pulsed light beam, and the modulation element 111 is configured to modulate the pulsed light beam emitted by the light source, for example, to increase the resolution of the projected pulsed light beam, i.e., to form the pulsed light beam 201, and to project the pulsed light beam 201 to the external object 20.

Alternatively, the modulation element 111 is, for example, but not limited to, a diffractive optical element. The diffractive optical element is used for diffracting the pulse light beam from the light source 110 to copy and expand the light beam emitted by the light source 110, so that the area of the emitted light beam is far larger than that of the light beam emitted by the light source 110, for example, the light beam can cover and fill the illuminated space.

Such as a DOE or the like.

Optionally, in some embodiments, the transmitting module 11 further includes: and a first lens unit 112, disposed between the light source 110 and the modulation element 111, for collimating or converging the light beams emitted by the sub light source group and transmitting the light beams to the modulation element 111.

In some embodiments, the receiving module 12 includes an image sensor, such as but not limited to, a pixel array 120 composed of a plurality of pixel cells for receiving the light beam 202 returned from the external object 20. Wherein one pixel cell is used to convert the received light beam 202 to form one depth information. Alternatively, the pixel unit may be a Charge-Coupled Device (CCD), a Complementary Metal Oxide Semiconductor (CMOS), an Avalanche Diode (AD), a Single Photon Avalanche Diode (SPAD), or the like. Alternatively, in some embodiments, the plurality of pixel units may not be arranged in an array, for example, in an irregular manner. This is not a limitation of the present application.

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.

Optionally, the receiving module 12 further includes: and a second lens unit 121, configured to receive the pulse light beam 202 returned from the external object 20, collimate or converge the pulse light beam 202, and transmit the collimated or converged pulse light beam to the plurality of pixel units.

In the embodiment of the present application, the emitting assembly 11 may emit pulsed light to the external object 20, the shorter the rising time of the pulsed light is, the higher the detection accuracy of the depth is, and in order to achieve the higher detection accuracy of the depth, extremely high requirements are set for the rising time and the falling time of the pulsed light. Typically within a few nanoseconds (ns).

In an embodiment, as shown in fig. 2, the emission module 11 further includes a driving circuit connected to the light source 110 for driving the light source 110 to emit light, the driving circuit includes a light source switching circuit 114 and a current limiting resistor 113, the power switching circuit 114 is connected to one end (cathode) of the light source 110, the other end (anode) of the light source 110 is connected to one end of the current limiting resistor 113, the other end of the current limiting resistor 113 is connected to a power voltage 117, the power switching circuit 114 is used for controlling the light source 110 to be turned on and off, and the current limiting resistor 113 performs current limiting and protecting functions on the light source 110. Specifically, the current limiting resistor 110 may control a voltage division of the power voltage 117 on the light source 110 to reduce a current flowing through the light source 110.

Optionally, in the embodiment of the present application, as shown in fig. 2, the power switch circuit 114 may include a power switch 1140 and a power switch driving circuit 1141. A power switch driving circuit 1141 connected to the power switch 1140 for driving the switch according to a driving signal V_INControls the power switch 1140 to be turned on and off. Optionally, the driving signal V_INThe square wave signal can be changed alternately between high and low levels, for example, the power switch driving circuit 1141 generates the driving signal V_INWhen the level is the first level, the power switch 1140 is controlled to be turned on, so that the light source 110 emits a light beam; or at the drive signal V_INWhen the level is the second level, the power switch 1140 is controlled to be turned off, so that the light source 110 stops emitting the light beam. Wherein the first level is a high level and the second level is a low level. The power switch 1140 is, for example, but not limited to, an NMOS transistor. Such as, but not limited to, 0 volts or a negative voltage, andthe first level is higher than the second level.

However, alternatively, in some embodiments, the first level may be a low level, and the second level may be a high level. Accordingly, the power switch 1140 is, for example, but not limited to, a PMOS transistor.

Optionally, in some embodiments, when the light source 110 is divided into a plurality of sub-light source groups, the power switch 1140 includes a plurality of control switches, each control switch for controlling the turning on and off of one of the plurality of sub-power supply groups.

The plurality of pixel units of the receiving module 12 are configured to receive the light beam returned from the external object 20 in a time-sharing manner when the plurality of sub-light source components emit light beams in the time-sharing manner, so as to obtain the depth information of the external object 20.

In a specific implementation, parasitic capacitance and parasitic inductance inevitably exist among the power switch 1140, the light source 110 and the circuit board of the TOF apparatus 10, which results in that the current flowing through the light source 110 cannot reach a set value at a very high speed (for example, several nanoseconds), and therefore, the rising edge of the light signal generated by the light source 110 is relatively gentle.

In view of this technical problem, in the embodiment of the present application, the driving circuit further includes a driving capacitor 116 connected in parallel to the current limiting resistor 113, in other words, the driving capacitor 116 may be added between the power voltage 117 and the light source 110. Thus, the value of the current flowing through the light source 110 is increased at the moment when the power switch 1140 is turned on, that is, the driving capacitor 116 provides a pulse current for the rising moment of the optical signal of the light source 110, thereby compensating the problem of slow current rise of the optical signal caused by the existence of parasitic capacitance and parasitic inductance. As can be seen from fig. 2, after the driving capacitor 116 is added, the rising edge of the optical signal becomes significantly steeper, and the rising time can be shortened to within 10 ns.

Optionally, in some embodiments, the driving circuit further includes:

and one end of the filter capacitor 115 is connected with the power supply voltage 117, and the other end of the filter capacitor 115 is grounded. The filter capacitor 115 is used to reduce the internal resistance of the light source 110, and influence of wires and the like on the rising edge of the optical signal.

Optionally, in some embodiments, the light source 110 is, for example, a vertical cavity surface emitting laser VCSEL or a light emitting diode LED.

As shown in fig. 3, an embodiment of the present application further provides an electronic apparatus 100, where the electronic apparatus 100 includes the TOF device 10. The electronic device 100 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 with TOF function requirements.

The processing module 13 may be an integrated circuit chip having signal processing capability. In implementation, the steps of the above method embodiments may be performed by integrated logic circuits of hardware in a processor or instructions in the form of software. The Processor may be a general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic device, or discrete hardware components. The various methods, steps, and logic blocks disclosed in the embodiments of the present application may be implemented or performed. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like. The steps of the method disclosed in connection with the embodiments of the present application may be directly implemented by a hardware decoding processor, or implemented by a combination of hardware and software modules in the decoding processor. The software module may be located in ram, flash memory, rom, prom, or eprom, registers, etc. storage media as is well known in the art. The storage medium is located in a memory, and a processor reads information in the memory and completes the steps of the method in combination with hardware of the processor.

The memory module described above may be either volatile memory or nonvolatile memory, or may include both volatile and nonvolatile memory. The non-volatile Memory may be a Read-Only Memory (ROM), a Programmable ROM (PROM), an Erasable PROM (EPROM), an Electrically Erasable PROM (EEPROM), or a flash Memory. Volatile Memory can be Random Access Memory (RAM), which acts as external cache Memory. By way of example, but not limitation, many forms of RAM are available, such as Static random access memory (Static RAM, SRAM), Dynamic Random Access Memory (DRAM), Synchronous Dynamic random access memory (Synchronous DRAM, SDRAM), Double Data Rate Synchronous Dynamic random access memory (DDR SDRAM), Enhanced Synchronous SDRAM (ESDRAM), Synchronous link SDRAM (SLDRAM), and Direct Rambus RAM (DR RAM).

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

The specific examples in the embodiments of the present application are only for helping those skilled in the art to better understand the embodiments of the present application, and do not limit the scope of the embodiments of the present application, and those skilled in the art may make various modifications and variations on the embodiments described above, and those modifications and variations fall within the scope of the present application.

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 transmit module of a time-of-flight TOF apparatus, comprising:

a light source for emitting a pulsed light beam; and

2. The transmit module of a time-of-flight TOF apparatus according to claim 1, wherein the drive circuit further comprises:

3. The transmit module of a time-of-flight TOF apparatus according to claim 2, wherein the power switch drive circuit is specifically configured to:

wherein the first level is different from the second level.

4. A transmit module for a time-of-flight TOF apparatus according to claim 3 wherein the first level is a high level and the second level is a low level; or, the first level is a low level, and the second level is a high level.

5. The transmit module of a time-of-flight TOF apparatus according to claim 1, wherein the drive circuit further comprises:

6. The time-of-flight TOF apparatus transmission module of claim 1 wherein said light source comprises a plurality of sub-light source groups, each sub-light source group comprising at least one sub-light source;

7. The time-of-flight TOF apparatus transmit module of claim 6 wherein the light source switch comprises a plurality of control switches, each control switch for controlling the turning on and off of one of the plurality of sub light source groups.

8. The transmit module of claim 1, wherein said current limiting resistor is connected to an anode of said light source and a cathode of said light source is connected to said light source switch.

9. The time of flight TOF apparatus transmit module of claim 1 wherein said light source is a VCSEL light source and said pulsed light beam is a square wave signal.

10. The time of flight TOF apparatus transmit module of claim 1, wherein the time of flight TOF apparatus is an I-TOF apparatus transmit module or a D-TOF apparatus transmit module.