Direct time-of-flight sensor module
Through the DToF sensor module, using VCSEL light source and SPAD photosensitive unit combined with collimating lens and diffraction optical elements, the accuracy problem of measuring the distance and angle from the projector to the screen is solved, high-precision multi-functional measurement is achieved, and the system integration and safety are improved.
Patent Information
- Application Number
- CN202421593686.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-05
- Publication Date
- 2025-09-12
- Estimated Expiration
- 2034-07-05
AI Technical Summary
Existing technologies make it difficult to accurately measure the distance and relative deflection angle from the projector to the screen at the same time, and the camera has optical distortion and privacy and security issues.
The direct time-of-flight (DToF) sensor module uses a VCSEL light source at the transmitting end and a SPAD photosensitive unit at the receiving end, combined with a collimating lens and a diffractive optical element, to achieve collimation and splitting of multiple light beams, and calculate the time difference of the light beams to measure distance and angle.
It achieves the simultaneous measurement of the distance and relative angle from the spatial plane to the sensor, improves system integration and measurement accuracy, and avoids optical distortion and privacy security risks caused by the camera.
Smart Images
Figure CN223333161U_ABST
Abstract
Description
Technical Field
[0001] This utility model patent application relates to the field of 3D depth sensing, and specifically to a direct time of flight (DToF) sensor module that can simultaneously obtain the distance and relative angle from a spatial plane to the sensor and a measurement system including the module. Background Art
[0002] Distance and angle detection have important applications in projection. The principle is as follows: A projector uses a set of projection lenses to project an image onto a screen. During this process, since the exact image distance cannot be determined in advance, the lens must be manually controlled to focus the image to ensure a clear image on the screen. Alternatively, a camera can be used to capture the screen, and the clarity of the captured image can be used to adjust the object distance of the projection lens to achieve a clear image. However, if the distance from the projector to the screen could be determined, the object distance of the projection lens could be adjusted more quickly and accurately, resulting in a better user experience. On the other hand, due to the variety of user scenarios, the projector may not be positioned perpendicular to the screen, resulting in keystone distortion. A projector with keystone correction can compensate for this distortion by reversing the projected image to achieve the desired effect. However, this function requires the relative deflection angle between the projector and screen. Currently, this angle is typically obtained by capturing the image through the imaging lens, then calculating the rotation angle in reverse, which is then adjusted by the projector to achieve a good projection effect. However, the problem with this method is that the imaging lens itself is also affected by the distortion of larger objects near and smaller objects far away. When the deflection angle is too large, it is difficult to accurately calculate the deflection angle, which affects the final adjustment effect.
[0003] A direct time-of-flight (DToF) sensor is an active optical sensor consisting of at least two main components: a transmitter (Tx) and a receiver (Rx). The Tx emits short laser pulses that illuminate the object being measured. The laser is then reflected by the object and partially received by the receiver.
[0004] Existing Technical Solution 1: A camera captures the projected image, determines whether the projector is in focus based on image clarity, and continuously adjusts the object distance of the projector lens to achieve the sharpest image. Angle detection measures the relative positions of the four corners of the image to determine the keystone distortion, which is then used to calculate the deflection angle.
[0005] Existing Technology Solution 2: A direct time-of-flight (DToF) sensor is an active optical sensor that calculates the distance to an object by recording the time difference between the Tx and Rx signals. A common method involves controlling a circuit signal to record the start time of a light signal and the end time of the Rx receiving the measured light signal. The time difference is the time t it takes for the laser to travel back and forth in the air. Given the speed of light C, the distance to the object can be calculated as d = 1 / 2 * C * t.
[0006] In the existing technical solution 1, this method is inevitably affected by whether the camera itself is accurately focused. At the same time, the lens itself has a certain depth of field, that is, the clarity of the images taken for objects within a certain range is basically the same, so it is impossible to accurately determine the position of the clearest image. As for the calculation of the deflection angle, since the camera itself also has optical distortion, it will cause errors in the angle calculation results. At the same time, with privacy protection becoming increasingly important today, imaging cameras can bring a sense of insecurity to users, especially when the imaging range also covers the entire projection information area, which poses a great risk to confidential content.
[0007] Conventional Solution 2 only calculates the linear distance from the device to the target location, but cannot calculate the relative deflection angle. However, by detecting the distance from the projector to the screen at several spatial angles, both the distance to the screen and the relative deflection angle between the two can be conveniently calculated. Utility Model Content
[0008] This application proposes a system solution based on the DToF method to simultaneously measure the distance and relative angle between a spatial plane and a sensor. This system can perform multiple functions with a single device, enriching the functional integration of the system and expanding the device's application scenarios.
[0009] One aspect of the present invention proposes a DToF sensor module, comprising: a transmitting end for emitting a laser beam toward a target plane; and a receiving end for receiving a reflected laser beam, wherein the transmitting end comprises: a vertical cavity surface emitting laser (VCSEL) light source for emitting laser; and an optical transmitting system for collimating the laser emitted by the VCSEL light source and splitting the collimated light beam into multiple light beams to form multiple light spots in the far field, and wherein the receiving end comprises: one or more optical lenses for converging the laser beam reflected from the target plane; and a single photon avalanche diode (SPAD) photosensitizing unit for processing the converged light signal into distance information, and the distance information is used to calculate the distance and relative angle between the DToF sensor module and the target plane, wherein the divergence angle of each of the multiple light beams is collimated.
[0010] One aspect of the present invention proposes a DToF sensor module, wherein the VCSEL light source is a single-point light source having one light-emitting point, the optical emission system includes a collimating lens and a diffraction optical element, and the collimating lens is composed of two lenses, wherein the laser emitted by the single-point light source is first collimated by the collimating lens and then split into multiple light beams by the diffraction optical element to form multiple light spots in the far field.
[0011] One aspect of the present invention proposes a DToF sensor module, wherein the VCSEL light source is a multi-point light source having multiple light-emitting points, the number of the multiple light-emitting points is greater than or equal to 3, the optical emission system includes a collimating lens composed of one or more lenses, and wherein the multiple laser beams emitted by the multi-point light source are collimated by the collimating lens to form multiple light spots in the far field.
[0012] One aspect of the present invention proposes a DToF sensor module, wherein the VCSEL light source is a single-point light source having one light-emitting point, and the optical emission system includes one or more diffraction optical elements, wherein the laser emitted by the single-point light source is collimated and split into multiple light beams by one or more diffraction optical elements to form multiple light spots in the far field.
[0013] One aspect of the present invention provides a DToF sensor module, wherein a divergence angle of each of the multiple light beams is less than or equal to 5°.
[0014] One aspect of the present invention provides a DToF sensor module, wherein a divergence angle of each of the multiple light beams is less than or equal to 3°.
[0015] One aspect of the present invention provides a DToF sensor module, wherein the number of formed light spots is greater than or equal to 3, and all the formed light spots are not arranged in a straight line.
[0016] One aspect of the present invention provides a DToF sensor module, wherein the number of formed light spots is greater than or equal to 3, and all the formed light spots are not arranged in a straight line.
[0017] One aspect of the present invention provides a DToF sensor module, wherein the collimating lens and / or the diffractive optical element in the optical emission system are made of a material that is transparent in the working band.
[0018] One aspect of the present invention proposes a DToF-based measurement system, including: a DToF sensor module according to the above aspects of the present invention, and a computing unit, which is configured to: determine multiple distance values based on the distance information provided by the DToF sensor module, determine the coordinate values of a point in three-dimensional space based on the multiple distance values, calculate a spatial plane that meets the coordinates of all points, and calculate the distance and angle from the spatial plane to the DToF sensor module.
[0019] The DToF sensor module according to the present application can simultaneously obtain the distance and relative angle from the spatial plane to the sensor, thereby improving the system integration and improving the application scenarios of the DToF sensor. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 This is a measurement diagram of the speckle structure DToF sensor module.
[0021] Figure 2 This is a structural diagram of a DToF sensor module that has both a collimating lens and a diffractive optical element.
[0022] Figure 3a It is a structural diagram of a single VCSEL light source.
[0023] Figure 3b This is a schematic diagram of the far-field spot of a single VCSEL light source.
[0024] Figure 3c This is a schematic diagram of the far-field light spot of a single VCSEL light source after passing through a collimating lens.
[0025] Figure 3d This is a schematic diagram of the far-field light spot of a single VCSEL light source after passing through a collimating lens + optical diffraction element.
[0026] Figure 4 This is a structural diagram of a multi-point DToF sensor module with a collimating lens.
[0027] Figure 5a It is a structural diagram of a VCSEL array light source.
[0028] Figure 5b This is a schematic diagram of the far-field spot of a single VCSEL light source.
[0029] Figure 5c This is a schematic diagram of the far-field light spot of the VCSEL array light source after passing through the collimating lens.
[0030] Figure 6 This is a structural diagram of a DToF sensor module with only diffraction optical elements on the transmitting end.
[0031] Figure 7a It is a structural diagram of a VCSEL light source.
[0032] Figure 7b This is a schematic diagram of the far-field spot of a single VCSEL light source.
[0033] Figure 7c This is a schematic diagram of the far-field light spot of a single VCSEL light source after passing through an optical diffraction element.
[0034] Figure 8 It is a flow chart of the algorithm used by the calculation unit to calculate distance and relative angle.
[0035] Figure 9 It is a schematic diagram of the spectral transmittance of the filter. DETAILED DESCRIPTION
[0036] Before proceeding with the detailed description below, it may be helpful to set forth the definitions of certain words and phrases used throughout this patent document. The terms "couple," "connect," and their derivatives refer to any direct or indirect communication or connection between two or more elements, regardless of whether those elements are in physical contact with each other. The terms "transmit," "receive," and "communicate," and their derivatives, encompass both direct and indirect communication. The terms "include," "comprise," and their derivatives, mean including, but not limited to. The term "or" is inclusive, meaning and / or. The phrase "associated with..." and its derivatives mean including, included within, interconnected, containing, contained within, connected or connected with, coupled or coupled with, communicate with, cooperate with, intertwine, juxtapose, approach, bound or bound with, have, have an attribute of, have a relationship with, or have a relationship with, etc. The term "controller" refers to any device, system, or portion thereof that controls at least one operation. Such a controller may be implemented using hardware, or a combination of hardware and software and / or firmware. The functionality associated with any particular controller may be centralized or distributed, whether local or remote. The phrase "at least one of," when used with a list of items, means that different combinations of one or more of the listed items may be used, and only one of the items in the list may be needed. For example, "at least one of A, B, and C" includes any of the following combinations: A, B, C, A and B, A and C, B and C, and A, B, and C.
[0037] Definitions for other specific words and phrases are provided throughout this patent document. Those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior and future uses of such defined words and phrases.
[0038] In this patent document, the application combination of modules and the division level of sub-modules are only used for illustration. Without departing from the scope of this disclosure, the application combination of modules and the division level of sub-modules can have different forms.
[0039] Figure 1 This is a measurement diagram of the speckle structure DToF sensor module.
[0040] Figure 1 The speckle structure DToF sensor module 101 shown is based on a single photon avalanche diode (SPAD). The DToF sensor module 101 includes a controller, a light source transmitter and a receiver. The transmitter mainly includes a vertical-cavity surface-emitting laser (VCSEL) light source, a VCSEL driving circuit, and a set of laser collimation and beam splitting systems. The receiver mainly includes a SPAD photosensitive unit, a SPAD control circuit, a SPAD readout circuit, and an optical system composed of one or more optical lenses. The measurement schematic diagram of the DToF sensor module 101 is shown in FIG. Figure 1 As shown, the transmitting end emits multiple collimated light beams, which are irradiated onto the target plane 102. The reflected light is received by the receiving end. The computing unit 103 calculates the time difference of the return signal and the optical path of each light beam, thereby obtaining the distance information in each direction. By reconstructing these position points in three-dimensional space, the spatial position of the target plane 102 is obtained, thereby calculating the distance from the target plane 102 to the sensor (i.e., the distance from the sensor to the target plane 102 along the central axis) and the relative deflection angle.
[0041] According to one embodiment of the present invention, a direct time-of-flight (DToF) sensor is an active light sensor, the components of which at the transmitting end Tx include an optical transmitting system consisting of a VCSEL light source, a VCSEL driving circuit, a collimating lens and a diffraction optical element; the components of which at the receiving end Rx include a SPAD photosensitive unit, a SPAD control circuit, a SPAD readout circuit and an optical lens group.
[0042] Figure 2 The structure diagram of the DToF sensor module with both a collimator lens and a diffractive optical element according to an embodiment of the present invention is shown. Figure 2As shown, the DToF sensor module 200 includes a transmitter and a receiver, which are housed in an outer structural frame 240. The transmitter mainly consists of a VCSEL light source and an optical transmission system. The optical transmission system includes a diffractive optical element 210 and an optical collimator 221 composed of two lenses. The diffractive optical element 210 includes two parts, namely an optical microstructure 211 and an optical substrate 212, both of which are transparent materials in the working band. Below the diffractive optical element 210 is the transmitter module cavity 220, which contains an optical collimator 221. A VCSEL light source 223 is placed below the collimator, and the light source is connected to the relevant control circuit 222. The receiving end includes a receiving filter 234, a receiving cavity 230, a receiving optical system 233, a SPAD photosensitive unit 232 and a readout circuit 231.
[0043] Figure 3a It is a structural diagram of a single VCSEL light source. Figure 3b This is a schematic diagram of the far-field spot of a single VCSEL light source. Figure 3c This is a schematic diagram of the far-field light spot of a single VCSEL light source after passing through a collimating lens. Figure 3d This is a schematic diagram of the far-field light spot of a single VCSEL light source after passing through a collimating lens + optical diffraction element.
[0044] The VCSEL light source is a single point light source, and its structural diagram is as follows Figure 3a As shown, the light source only emits a single beam. The light beam emitted by the VCSEL light source has a large divergence angle, and its far-field spot diagram is shown in Figure 3b As shown. The light spot emitted by the light source needs to be collimated by a collimator 221. The divergence angle of the collimated light beam is greatly reduced. Generally, the full angle is within 5°, preferably within 3°. The far-field light spot diagram of the light spot after collimation is as shown in FIG. Figure 3c After the collimation, the light spot needs to be expanded by the diffractive optical element 210 to form a multi-beam system. Each beam of the expanded multi-beam is also collimated, so that multiple light spots will be formed in the far field, as shown in FIG. Figure 3d The characteristic of this light spot is that its number is greater than or equal to 3, and all its light spots cannot be arranged in a straight line, such as Figure 3d The arrangement shown is one of the feasible and good arrangements. In addition, the collimating lens and the optical diffraction element in the optical launch system are both made of materials that are transparent in the working band.
[0045] The collimated multiple beams of light are irradiated onto the target plane, and after being reflected by the target plane, the reflected light passes through the receiving end filter 234 and enters the receiving cavity 230. The spectral transmittance of the filter can be referred to Figure 9 As shown, Figure 9This is a schematic diagram of the spectral transmittance of the filter, which is characterized by matching the central wavelength of the laser at the transmitting end and is a narrowband filter with a certain transmission bandwidth. The reflected light passes through the receiving optical system 233 composed of a lens, and is then collected and received by the SPAD photosensitive unit 232. The SPAD photosensitive unit 232 processes the received light signal into distance information, which is then input into the calculation unit through the readout circuit 231. The calculation unit uses the distance information to calculate the final required distance and relative angle between the sensor and the target plane. The calculation process is as follows: Figure 8 As shown, Figure 8 The outer structural frame 240 of the entire module plays a role in fixing and protecting the components.
[0046] According to another embodiment of the present invention, a direct time-of-flight (DToF) sensor is an active optical sensor, wherein the components of the transmitter Tx include: a VCSEL light source with multiple light-emitting points, a VCSEL driving circuit, and a collimating lens group consisting of one or more lenses; the components of the receiver Rx include: a SPAD photosensitive unit, a SPAD control circuit, a SPAD readout circuit, and an optical lens group consisting of one or more lenses. Its structure is as follows Figure 4 shown.
[0047] Figure 4 This is a structural diagram of a multi-point DToF sensor module with a collimating lens. Figure 4 The optical emission system 421 is shown, which is composed of an optical collimator composed of two lenses. A VCSEL light source 423 is placed below the collimator, and the light source is connected to the relevant control circuit 422.
[0048] Figure 5a It is a structural diagram of a VCSEL array light source. Figure 5b This is a schematic diagram of the far-field spot of a single VCSEL light source. Figure 5c This is a schematic diagram of the far-field light spot of the VCSEL array light source after passing through the collimating lens.
[0049] The VCSEL light source is a multi-point light source, and its structural diagram is as follows Figure 5a As shown, the light source has multiple light-emitting points (the number is greater than or equal to 3), emits multiple light beams, and the light sources are not arranged on the same straight line. The light beam emitted by the light source has a large divergence angle, and its far-field spot diagram is as follows Figure 5b As shown (because the distance between multiple light points is very small, generally a few hundred microns, the light spots in the far field will basically overlap together, and the difference between multiple points and single points cannot be seen, so Figure 3b and Figure 5bThe morphology is basically the same). The light spot emitted by the light source needs to be collimated by the collimator 421. The divergence angle of the collimated light beam is greatly reduced. Generally, the full angle is within 5°, preferably within 3°. The far-field light spot diagram of the light spot after collimation is as follows Figure 5c The characteristic of this light spot is that its number is greater than or equal to 3, and all its light spots cannot be arranged in a straight line, as shown in Figure 5c The arrangement shown is one of the feasible and good arrangements. In addition, the collimating lens in the optical launch system is made of a material that is transparent in the working band.
[0050] The collimated multiple beams of light are irradiated onto the target plane, and after being reflected by the target plane, the reflected light passes through the receiving end filter 434 and enters the receiving cavity 430. The spectral transmittance of the filter can be referred to Figure 9 As shown, it is characterized by matching the central wavelength of the laser at the transmitting end and being a narrowband filter with a certain transmission bandwidth. The reflected light passes through the receiving optical system 433 composed of a lens, and is then collected and received by the SPAD photosensitive unit 432. The SPAD photosensitive unit 432 processes the received light signal into distance information, which is then input into the calculation unit through the readout circuit 431. The calculation unit calculates the final required distance and relative angle between the sensor and the target plane based on the distance information. The calculation process is as follows: Figure 8 The outer structural frame 440 of the entire module plays a role in fixing and protecting the components.
[0051] According to another embodiment of the present invention, a direct time-of-flight (DToF) sensor is an active optical sensor, wherein the components of the transmitter Tx include: a VCSEL light source, a VCSEL driving circuit, and an optical transmission system composed of one or more diffractive optical elements; the components of the receiver Rx include: a SPAD photosensitive unit, a SPAD control circuit, a SPAD readout circuit, and an optical lens. Its structure is as follows Figure 6 shown.
[0052] Figure 6 This is a structural diagram of a DToF sensor module with only diffraction optical elements on the transmitting end. Figure 6 The optical transmission system is shown as consisting of a diffractive optical element 621, which performs the dual optical functions of collimating and splitting the VCSEL light source 623 below. The VCSEL light source 623 is positioned below the diffractive optical element 621, which is connected to the associated control circuit 622. The optical transmission system can also be composed of multiple diffractive optical elements.
[0053] Figure 7a It is a structural diagram of a VCSEL light source. Figure 7b This is a schematic diagram of the far-field spot of a single VCSEL light source. Figure 7cThis is a schematic diagram of the far-field light spot of a single VCSEL light source after passing through an optical diffraction element.
[0054] The VCSEL light source is a single point light source, and its structural diagram is as follows Figure 7a As shown, the light source only emits a single beam. The light beam emitted by the light source has a large divergence angle, and its far-field spot diagram is shown as follows Figure 7b As shown. The diffractive optical element 621 is required to collimate the light spot emitted by the light source. The divergence angle of the collimated light beam is greatly reduced. Generally, the full angle is within 5°, preferably within 3°. At the same time, the diffractive optical element 621 also has the function of splitting the light beam, that is, dividing a light beam into multiple light beams with different directions. Each beam of the expanded multiple light beams is also collimated, so that multiple light spots will be formed in the far field, as shown in FIG. Figure 7c The characteristic of this light spot is that its number is greater than or equal to 3, and all its light spots cannot be arranged in a straight line, as shown in Figure 7c The arrangement shown is one of the feasible and good arrangements. In addition, the optical diffraction element in the optical emission system is made of a material that is transparent in the working wavelength band.
[0055] The collimated multiple beams of light are irradiated onto the target plane, and after being reflected by the target plane, the reflected light passes through the receiving end filter 634 and enters the receiving cavity 630. The spectral transmittance of the filter can be referred to Figure 9 As shown, it is characterized by matching the central wavelength of the laser at the transmitting end and being a narrowband filter with a certain transmission bandwidth. The reflected light passes through the receiving optical system 633 composed of a lens, and is then collected and received by the SPAD photosensitive unit 632. The SPAD photosensitive unit 632 processes the received light signal into distance information, which is then input into the calculation unit through the readout circuit 631. The calculation unit uses the distance information to calculate the final required distance and relative angle between the sensor and the target plane. The calculation process of the calculation unit is shown as follows: Figure 8 The outer structural frame 640 of the entire module plays a role in fixing and protecting the components.
[0056] This utility model proposes a system solution for simultaneously measuring angle and distance based on the direct time-of-flight method. Multiple functions are completed through a single device, which enriches the functional integration of the system and improves the detection accuracy of the device.
[0057] Although the present disclosure has been described with exemplary embodiments, various changes and modifications may be suggested to one skilled in the art. It is intended that the present disclosure encompass such changes and modifications as fall within the scope of the appended claims.
[0058] Any description in this utility model should not be construed as implying that any particular element, step, or function is an essential element that must be included in the scope of the claims. The scope of the patented subject matter is limited only by the claims.
Claims
1. A direct time-of-flight (DToF) sensor module, characterized in that include: A transmitting end, used for transmitting a laser beam toward a target plane; and The receiving end is used to receive the reflected laser beam. Wherein, the transmitting end includes: A vertical cavity surface emitting laser (VCSEL) light source for emitting laser light; and an optical emission system for collimating the laser light emitted by the VCSEL light source and splitting the collimated light beam into multiple light beams to form multiple light spots in the far field, and Wherein, the receiving end includes: one or more optical lenses for converging the laser beam reflected from the target plane; and The single-photon avalanche diode (SPAD) photosensitive unit processes the converged light signal into distance information, which is used to calculate the distance and relative angle between the DToF sensor module and the target plane. Wherein, the divergence angle of each light beam in the multiple light beams is collimated.
2. The direct time-of-flight (DToF) sensor module according to claim 1, wherein: The VCSEL light source is a single point light source with one light emitting point. The optical launch system includes a collimating lens and a diffractive optical element, and The collimating lens is composed of two lenses. The laser emitted by the single point light source is first collimated by a collimating lens and then beam-split into multiple beams by a diffraction optical element to form multiple light spots in the far field.
3. The direct time-of-flight (DToF) sensor module according to claim 1, wherein: The VCSEL light source is a multi-point light source having multiple light-emitting points, and the number of the multiple light-emitting points is greater than or equal to 3. The optical launch system includes a collimating lens composed of one or more lenses, and The multiple laser beams emitted by the multi-point light source are collimated by a collimating lens to form multiple light spots in the far field.
4. The direct time-of-flight (DToF) sensor module according to claim 1, wherein: The VCSEL light source is a single point light source with one light emitting point. The optical launch system includes one or more diffractive optical elements, The laser emitted by the single point light source is collimated by one or more diffraction optical elements and split into multiple light beams to form multiple light spots in the far field.
5. The direct time-of-flight (DToF) sensor module according to any one of claims 1 to 4, characterized in that: A divergence angle of each of the plurality of light beams is less than or equal to 5°.
6. The direct time-of-flight (DToF) sensor module according to any one of claims 1 to 4, characterized in that: A divergence angle of each of the plurality of light beams is less than or equal to 3°.
7. The direct time-of-flight (DToF) sensor module according to any one of claims 1 to 4, characterized in that: The number of the formed light spots is greater than or equal to 3, and all the formed light spots are not arranged in a straight line.
8. The direct time-of-flight (DToF) sensor module according to any one of claims 1 to 4, characterized in that: The number of the formed light spots is greater than or equal to 3, and all the formed light spots are not arranged in a straight line.
9. The direct time-of-flight (DToF) sensor module according to any one of claims 2 to 4, characterized in that: The collimating lens and / or diffractive optical element in the optical emission system is made of a material that is transparent in the working band.