A voltage drift test circuit and test method for a ToF image sensor

Abstract

This invention discloses a voltage drift test circuit and method for a ToF image sensor. The invention uses a microcontroller to send resistance adjustment control signals to control the output resistance of a digital potentiometer, thereby changing the output voltage of the power supply module and thus achieving voltage drift testing of the ToF image sensor. It employs a digitally controlled method to adjust the resistance value to simulate voltage changes, offering advantages such as flexibility, high adjustment accuracy, and low cost. This invention also has strong scalability, allowing control of multiple digital potentiometers and thus the output voltages of multiple power supply modules via a serial communication bus, and can optimize the interference from uncertainties introduced by external DC power supplies.

Description

Technical Field

[0001] This invention relates to the field of image sensor technology, and in particular to a voltage drift test circuit and test method for a ToF image sensor. Background Technology

[0002] Binocular ranging, structured light, and time-of-flight (ToF) are the three mainstream 3D imaging technologies today. Among them, ToF has been gradually applied to fields such as gesture recognition, 3D modeling, autonomous driving, and machine vision due to its advantages such as simple principle, simple and stable structure, and long measurement distance. The working principle of ToF technology is as follows: a light source (such as VCSEL or LED) emits continuously modulated light. After the emitted light shines on the surface of the object being measured, it is reflected back. The reflected light is captured by the ToF image sensor. By calculating the time difference or phase difference between the emitted light and the reflected light, the depth / distance between the object being measured and the camera can be obtained.

[0003] Currently, most Time-of-Flight (ToF) image sensors on the market use controllable DC power supplies to simulate voltage changes and test ranging errors caused by voltage drift. However, controllable DC power supplies have limitations such as large size and high cost, and different controllable DC power supplies produce different voltage changes, which can interfere with the final test results and hinder the rapid and accurate testing of the ranging error caused by voltage drift. Summary of the Invention

[0004] The purpose of this invention is to provide a low-cost, fast, and accurate voltage drift test circuit and method for ToF image sensors that can quickly and accurately test ranging errors caused by voltage drift and avoid interference with test results. This invention addresses the technical problems of existing devices that use controllable DC power supplies to simulate voltage changes, such as large size, high cost, and interference with test results.

[0005] To achieve the above objectives, the present invention provides a voltage drift test circuit for a ToF image sensor, comprising: a microcontroller for sending a resistance adjustment control signal; at least one digital potentiometer electrically connected to the microcontroller via a serial communication bus; and at least one power supply module, each of the power supply modules being electrically connected to the digital potentiometer and the ToF image sensor; wherein the resistance adjustment control signal carries an instruction indicating a target address of the target digital potentiometer and a target resistor cursor position, the target digital potentiometer receives the resistance adjustment control signal based on the target address and adjusts the resistor cursor position to the target resistor cursor position, and the power supply module electrically connected to the target digital potentiometer changes the output voltage output to the ToF image sensor according to the output resistance corresponding to the target resistor cursor position, thereby performing a voltage drift test on the ToF image sensor.

[0006] To achieve the above objectives, the present invention also provides a voltage drift test method for a ToF image sensor, using the voltage drift test circuit of the ToF image sensor described in the present invention. The method includes: (1) sending a resistance adjustment control signal using a microcontroller, the resistance adjustment control signal carrying an instruction indicating the target address of the target digital potentiometer and the position of the target resistor vernier; (2) the target digital potentiometer corresponding to the target address responding to the resistance adjustment control signal and adjusting its resistor vernier position to the target resistor vernier position; (3) the target power module connected to the target digital potentiometer changing the output voltage based on the output resistance corresponding to the target resistor vernier position and outputting it to the ToF image sensor; (4) detecting the image clarity or ranging accuracy of the ToF image sensor under the current output voltage; and (5) repeating the above steps (1) to (4) to obtain the changes in the image clarity or ranging accuracy of the ToF image sensor under different output voltages, thereby completing the voltage drift test of the ToF image sensor.

[0007] This invention uses a microcontroller to send resistance adjustment control signals to control the output resistance of a digital potentiometer, thereby changing the output voltage of the power supply module and enabling voltage drift testing of a ToF image sensor. It employs a digitally controlled method to adjust the resistance value to simulate voltage changes, offering advantages such as flexibility, high adjustment accuracy, and low cost. This invention also has strong scalability, allowing control of multiple digital potentiometers and thus the output voltages of multiple power supply modules via a serial communication bus. Furthermore, it can optimize the interference from uncertainties introduced by external DC power supplies. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 This is a structural block diagram of a voltage drift test circuit for a ToF image sensor provided in an embodiment of the present invention;

[0010] Figures 2A-2B This is a circuit connection diagram of a voltage drift test circuit for a ToF image sensor provided in an embodiment of the present invention;

[0011] Figure 3 This is a flowchart of a voltage drift test method for a ToF image sensor provided in an embodiment of the present invention. Detailed Implementation

[0012] The technical solutions in the embodiments of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0013] To address the limitations of using controllable DC power supplies to simulate voltage changes in ToF image sensors for ranging errors due to voltage drift, such as the large size and high cost of controllable DC power supplies, and the discrepancies in voltage changes caused by different controllable DC power supplies leading to interference with the final test results, this invention provides a voltage drift testing circuit for ToF image sensors. The circuit includes: a microcontroller for sending a resistance adjustment control signal; at least one digital potentiometer electrically connected to the microcontroller via a serial communication bus; and at least one power module, each power module electrically connected to both the digital potentiometer and the ToF image sensor. The resistance adjustment control signal carries an instruction indicating a target address and a target resistor cursor position for the target digital potentiometer. The target digital potentiometer receives the resistance adjustment control signal based on the target address and adjusts the resistor cursor position to the target resistor cursor position. The power module electrically connected to the target digital potentiometer changes the output voltage to the ToF image sensor according to the output resistance corresponding to the target resistor cursor position, thereby testing the voltage drift of the ToF image sensor.

[0014] The circuit described in this invention uses a microcontroller to send resistance adjustment control signals to control the output resistance of a digital potentiometer, thereby changing the output voltage of the corresponding power supply module and thus enabling voltage drift testing of a ToF image sensor. Employing a digitally controlled method to adjust the resistance value and simulate voltage changes offers advantages such as flexibility, high adjustment accuracy, and low cost. This invention also has strong scalability; it can control multiple digital potentiometers and thus the output voltage of multiple power supply modules via a serial communication bus, and it can optimize the interference from uncertainties introduced by external DC power supplies.

[0015] Please refer to the following: Figures 1-2A ~ Figure 2B ,in, Figure 1 This is a structural block diagram of a voltage drift test circuit for a ToF image sensor according to an embodiment of the present invention. Figures 2A-2B This is a circuit connection diagram of a voltage drift test circuit for a ToF image sensor provided in an embodiment of the present invention.

[0016] like Figure 1 As shown, the circuit described in this embodiment includes a microcontroller 11, two digital potentiometers 121 and 122, and four power supply modules 131, 132, 133, and 134. That is, each digital potentiometer is electrically connected to two power supply modules, thereby enabling voltage regulation of the four internal power supply modules of the ToF image sensor 19.

[0017] ToF image sensors typically have multiple internal power supply modules, such as a 1.2V core power supply module, a 2.8V analog power supply module, a 3.3V external interface power supply module, and a 1.8V pixel power supply module. Different internal power supply modules are connected to corresponding power supply modules for power supply. To improve layout and reduce wiring, two digital potentiometers are used, each electrically connected to two power supply modules, to supply power to each internal power supply module of the ToF image sensor, thereby enabling voltage drift testing of the ToF image sensor. In other embodiments, one digital potentiometer can be used, each electrically connected to four power supply modules, to supply power to each internal power supply module of the ToF image sensor. The voltage adjustment range of each power supply module is greater than or equal to the difference between the center voltage of the corresponding internal power supply module and a preset threshold, and less than or equal to the sum of the center voltage of the corresponding internal power supply module and the preset threshold. For example, if the preset threshold can be 0.5V, then for a 2.8V analog power supply module, the voltage adjustment range of the corresponding power supply module can be [2.3V, 3.3V].

[0018] like Figure 1As shown, the microcontroller unit (MCU) 11 is used to send a resistance adjustment control signal. The resistance adjustment control signal carries an instruction indicating the target address and target resistor cursor position of the target digital potentiometer, as well as an instruction indicating the target power module. This allows the resistance adjustment control signal to be sent to the corresponding digital potentiometer and its resistor cursor position to be adjusted, thereby changing the output voltage of the corresponding power module. In some embodiments, the microcontroller 11 further responds to instructions from the PC host computer 10 by sending the resistance adjustment control signal to the digital potentiometers 121 / 122 via the serial communication bus 101.

[0019] The serial communication bus (Inter-Integrated Circuit, IIC) 101 is a multi-master serial bus, also known as I2C, which belongs to the half-duplex synchronous transmission type bus. In some embodiments, the serial communication bus 101 includes a serial data bus SDA and a serial clock bus SCL. The serial data bus SDA is electrically connected to the external power supply VCC through a pull-up resistor R1 (e.g., a 10K resistor), and the serial clock bus SCL is electrically connected to the external power supply VCC through a pull-up resistor R2 (e.g., a 10K resistor). Both the serial data bus SDA and the serial clock bus SCL are bidirectional I / O lines.

[0020] like Figure 2A As shown, the serial communication bus 19 uses the serial data bus SDA and the serial clock bus SCL connected to the target components (e.g., the microcontroller 11 and the digital potentiometers 121, 122) to transmit information; the serial data bus SDA and the serial clock bus SCL are electrically connected to the VCC pin of the microcontroller 11 through corresponding pull-up resistors inside the microcontroller 11, and then electrically connected to the external power supply VCC.

[0021] Please continue reading. Figure 1The digital potentiometers 121 and 122 are both electrically connected to the microcontroller 11 via a serial communication bus 101. The digital potentiometers 121 / 122 can receive the resistance adjustment control signal based on the target address and adjust the resistance vernier position to the target resistance vernier position. The operation of the digital potentiometer is similar to that of a traditional potentiometer, but the digital potentiometer uses electronic switches and digital signals instead of a mechanical vernier for operation. Specifically, the digital potentiometer connects a series of small-value resistors in series with electronic switches located at the intersections of every two resistors. Only one electronic switch can be closed at a time, and the position of the closed electronic switch at the intersection (i.e., the resistance vernier position) determines the resistance ratio. The digital potentiometer uses a numerical control method to adjust the resistance value, offering significant advantages such as flexibility, high adjustment accuracy, contactless operation, low noise, resistance to contamination, vibration resistance, anti-interference, small size, and long lifespan, which can reduce the overall cost of the voltage drift test circuit.

[0022] In some embodiments, all digital potentiometers 121 and 122 are identical and have the same initial power-on resistor cursor position, which is recorded in the microcontroller 11 as a voltage reference value to ensure voltage consistency of the ToF image sensor 19. Based on the reference range of different supply voltages for the ToF image sensor 19, the initial power-on resistor cursor position is reasonably selected, and this value is recorded in the microcontroller 11 as a voltage reference value to ensure voltage consistency of the ToF image sensor 19 and avoid interference caused by voltage errors.

[0023] In some embodiments, the initial power-on resistor cursor position can be the position corresponding to the center point potential of the digital potentiometers 121 and 122. For example, for a 10K digital potentiometer, the initial power-on resistor cursor position is set to 5K.

[0024] In some embodiments, the digital potentiometer is a 64-bit, 128-bit, or 256-bit digital potentiometer. The resolution of the digital potentiometer is related to the number of control nodes (number of taps / bits) in the resistor network; the higher the number of control nodes, the higher the resolution. A suitable digital potentiometer can be selected based on the voltage drift test accuracy requirements of the ToF image sensor. In some embodiments, the digital potentiometer may employ non-volatile memory to enable programmable output power during testing.

[0025] like Figure 2AAs shown, in some embodiments, all the digital potentiometers 121 and 122 have four output ports A1 to A4. Since each output port can be electrically connected to a power supply module, the control of multiple power supply modules can be expanded. In some embodiments, each of the digital potentiometers 121 / 122 determines a unique address through different connection methods of its address selection interface. The address selection interfaces ADDR0 and ADDR1 of each digital potentiometer determine a unique address through different connection methods, enabling the microcontroller 11 to communicate normally with any digital potentiometer. For example, the address selection interface of the digital potentiometer 121 arranged in Figure 2 is encoded as: ADDR0 = 1, ADDR1 = 1 (both ports are connected to a high-level external power supply VCC in the figure); correspondingly, its slave address = 0x20. The address selection interface of the digital potentiometer 122 is encoded as: ADDR0 = 1, ADDR1 = 0 (the ADDR0 port is connected to a high-level external power supply VCC in the figure, and the ADDR1 port is connected to a low-level ground GND); correspondingly, its slave address = 0x23. To clearly illustrate the inventive points of this invention, only the names of some ports related to the inventive points of this invention are shown in the figure. Other corresponding ports can be referenced from the basic settings of a digital potentiometer.

[0026] Please continue reading. Figure 1 Power modules 131 and 132 are both electrically connected to the digital potentiometer 121 and to the ToF image sensor 19; power modules 133 and 134 are both electrically connected to the digital potentiometer 122 and to the ToF image sensor 19. After the target digital potentiometer and the target resistor cursor position are determined based on the resistance adjustment control signal, the target digital potentiometer adjusts its own resistor cursor position to the target resistor cursor position to form a corresponding output resistance. The power modules electrically connected to the target digital potentiometer change the output voltage output to the ToF image sensor according to the output resistance corresponding to the target resistor cursor position, thereby performing voltage drift testing on the ToF image sensor. For example, when the resistance adjustment control signal determines that the position of the digital potentiometer 121 needs to be adjusted to the target resistance position, the digital potentiometer 121 responds to the resistance adjustment control signal by adjusting its own resistance position to the target resistance position to form a corresponding output resistance; the corresponding output port is electrically connected to the power supply module 131 and power supply module 132 of the digital potentiometer 121, and the output voltage is changed based on the output resistance corresponding to the target resistance position to achieve the purpose of simulating voltage drift testing.

[0027] like Figure 2BAs shown, in some embodiments, the power supply modules 131-134 employ low-dropout linear regulators (LDOs). The VIN pin of the LDO is electrically connected to the corresponding reference voltage terminals VREF1-VREF4 to receive reference voltages Vref1-Vref4. Its VOUT pin is electrically connected to the ToF image sensor 19 (providing output voltages VOUT1-VOUT4 to the corresponding internal power supply module of the ToF image sensor 19) and simultaneously electrically connected to the corresponding sliding port (W port) of the corresponding digital potentiometer. Its FB pin is electrically connected to the corresponding output port (A port) of the corresponding digital potentiometer through a voltage divider unit. That is, the corresponding digital potentiometer and the voltage divider unit combine to form a digitally controlled adjustable resistor, connected between the VOUT pin and the FB pin of the LDO. The voltage divider unit can be composed of two offset resistors with the same resistance value. The resistance value of the digital potentiometer acts on the FB pin of the LDO, and the output voltage formula of the LDO is VOUTn = Vrefn(1+R). 上 / R 下 R in the formula 上 The output resistor of the digital potentiometer is connected to an upper bias resistor (i.e., resistors R137 / R139 / R141 / R143 in the corresponding voltage divider unit shown in the diagram). 下 This refers to the lower bias resistor (resistors R138 / R140 / R142 / R144 in the corresponding voltage divider unit shown in the diagram), and Vrefn is a reference voltage adapted to the supply voltage required by the corresponding internal power supply module of the ToF image sensor. Therefore, when the target digital potentiometer adjusts its own resistor vertex position to the target resistor vertex position, the corresponding output resistance changes, which alters the voltage division ratio of the corresponding voltage divider unit, thereby changing the output voltage VOUTn of the corresponding power supply module, achieving the purpose of simulating voltage drift testing.

[0028] As can be seen from the above, this embodiment uses a microcontroller to send resistance adjustment control signals to control the output resistance of a digital potentiometer, thereby changing the output voltage of the power supply module and thus realizing voltage drift testing of a ToF image sensor. It uses a digital control method to adjust the resistance value to simulate voltage changes, offering advantages such as flexibility, high adjustment accuracy, and low cost. This invention has strong scalability; it can control multiple digital potentiometers via a serial communication bus, thereby controlling the output voltage of multiple power supply modules, and it can optimize the interference of uncertainties introduced by external DC power supplies.

[0029] Based on the same inventive concept, the present invention also provides a voltage drift test method for a ToF image sensor, which can be used to perform voltage drift test using the voltage drift test circuit of the ToF image sensor described above.

[0030] Please see Figure 3 This is a flowchart of a voltage drift testing method for a ToF image sensor provided in an embodiment of the present invention. Figure 3 The voltage drift test method for the ToF image sensor described in this embodiment includes the following steps: S31, a microcontroller sends a resistance adjustment control signal, the resistance adjustment control signal carrying an instruction indicating the target address of the target digital potentiometer and the position of the target resistor vernier; S32, the target digital potentiometer corresponding to the target address responds to the resistance adjustment control signal and adjusts its resistor vernier position to the target resistor vernier position; S33, the target power module connected to the target digital potentiometer changes its output voltage based on the output resistance corresponding to the target resistor vernier position and outputs it to the ToF image sensor; S34, the image clarity or ranging accuracy of the ToF image sensor under the current output voltage is detected; and S35, steps S31 to S34 are repeated to obtain the changes in the image clarity or ranging accuracy of the ToF image sensor under different output voltages, thus completing the voltage drift test of the ToF image sensor.

[0031] Within the scope of this inventive concept, embodiments can be described and illustrated based on modules that perform one or more of the described functions. These modules (also referred to herein as units, etc.) can be physically implemented by analog and / or digital circuitry, such as logic gates, integrated circuits, microprocessors, microcontrollers, memory circuits, passive electronic components, active electronic components, optical components, hardwired circuits, etc., and can optionally be driven by firmware and / or software. The circuitry can, for example, be implemented in one or more semiconductor chips. The circuitry constituting a module can be implemented by dedicated hardware, or by a processor (e.g., one or more programmed microprocessors and associated circuitry), or by a combination of dedicated hardware performing some functions of the module and a processor performing other functions of the module. Without departing from the scope of this inventive concept, each module of an embodiment can be physically divided into two or more interactive and discrete modules. Similarly, without departing from the scope of this inventive concept, the modules of an embodiment can be physically combined into more complex modules.

[0032] Generally, terms can be understood at least partially from their usage in context. For example, the term "one or more" as used herein depends at least in part on the context and can be used to describe a feature, structure, or characteristic in a singular sense, or in a plural sense to describe a combination of features, structures, or characteristics. Additionally, the term "based on" can be understood not necessarily to express an exclusive set of factors, but rather, alternatively, also depends at least in part on the context, allowing for the presence of other factors that are not necessarily explicitly described.

[0033] It should be noted that the terms "comprising" and "having," and their variations, used in this invention document are intended to cover non-exclusive inclusion. The terms "first," "second," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence, unless explicitly indicated by the context. It should be understood that such data used interchangeably where appropriate. Furthermore, embodiments and features within embodiments of this invention can be combined with each other unless otherwise specified. In addition, descriptions of well-known components and technologies have been omitted in the above description to avoid unnecessarily obscuring the concepts of this invention. In the various embodiments described above, each embodiment focuses on its differences from other embodiments; similar or identical parts between embodiments can be referred to interchangeably.

[0034] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A voltage drift testing circuit for a ToF image sensor, characterized in that, include: The microcontroller is used to send resistance adjustment control signals; At least one digital potentiometer is electrically connected to the microcontroller via a serial communication bus; as well as Multiple power modules are provided, each of which is electrically connected to the digital potentiometer and the ToF image sensor. Each power module uses a low-dropout linear regulator. The VIN pin of the low-dropout linear regulator is electrically connected to the corresponding reference voltage terminal, its VOUT pin is electrically connected to the ToF image sensor and also electrically connected to the corresponding sliding port of the corresponding digital potentiometer, and its FB pin is electrically connected to the corresponding output port of the corresponding digital potentiometer through a voltage divider unit. The resistor adjustment control signal carries an instruction indicating the target address of the target digital potentiometer and the target resistor cursor position. The target digital potentiometer receives the resistor adjustment control signal based on the target address and adjusts the resistor cursor position to the target resistor cursor position. The power module electrically connected to the target digital potentiometer changes the output voltage to the ToF image sensor according to the output resistance corresponding to the target resistor cursor position, thereby performing voltage drift testing on the ToF image sensor.

2. The circuit according to claim 1, characterized in that, The circuit includes two digital potentiometers, each of which is electrically connected to two power modules, and each power module is electrically connected to an internal power supply module of the ToF image sensor; wherein, the voltage adjustment range of each power module is greater than or equal to the difference between the center voltage of the corresponding internal power supply module and a preset threshold, and less than or equal to the sum of the center voltage of the corresponding internal power supply module and the preset threshold.

3. The circuit according to claim 1, characterized in that, The microcontroller further responds to the signals from the PC host computer by sending resistance adjustment control signals to the digital potentiometer via the serial communication bus.

4. The circuit according to claim 1, characterized in that, The serial communication bus includes a serial data bus and a serial clock bus, which are respectively connected to an external power supply through corresponding pull-up resistors.

5. The circuit according to claim 1, characterized in that, All the digital potentiometers used are identical and are set to the same initial power-on resistance cursor position, which is recorded in the microcontroller as a voltage reference value to ensure voltage consistency of the ToF image sensor.

6. The circuit according to claim 5, characterized in that, The initial power-on position of the resistor vernier is the position of the resistor vernier corresponding to the center point potential of the digital potentiometer.

7. The circuit according to claim 1, characterized in that, All of the digital potentiometers described are 64-bit, 128-bit, or 256-bit digital potentiometers with four output ports.

8. The circuit according to claim 1, characterized in that, Each of the digital potentiometers has a unique address determined by the different connection methods of its address selection interface.

9. A method for testing the voltage drift of a ToF image sensor, characterized in that, The method employs the voltage drift test circuit of the ToF image sensor as described in any one of claims 1 to 8, the method comprising: (1) A microcontroller is used to send a resistance adjustment control signal, the resistance adjustment control signal carrying an instruction indicating the target address of the target digital potentiometer and the position of the target resistor vernier; (2) The target digital potentiometer corresponding to the target address responds to the resistance adjustment control signal and adjusts its resistance vernier position to the target resistance vernier position; (3) The target power module connected to the target digital potentiometer changes the output voltage based on the output resistance corresponding to the vernier position of the target resistor, and outputs it to the ToF image sensor; (4) Detect the image sharpness or ranging accuracy of the ToF image sensor under the current output voltage; and (5) Repeat steps (1) to (4) above to obtain the changes in image clarity or ranging accuracy of the ToF image sensor under different output voltages, and complete the voltage drift test of the ToF image sensor.

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