Frequency modulation circuit of TOF camera

Abstract

The embodiment of the utility model provides a frequency modulation circuit of a TOF camera, and the circuit comprises an RX module which comprises a TOF sensor which is used for outputting a CMOS single-end level signal with a predetermined modulation frequency; the TX module comprises a laser driver which is connected with the TOF sensor and is used for outputting a laser driving signal and a VCSEL laser which is connected with the laser driver and is used for adjusting the light emitting frequency under the driving of the laser driving signal; the RX module further comprises a differential driver, the single-end signal input end of the differential driver is connected with the TOF sensor, two differential signal output ends of the differential driver are connected with the positive electrode and the negative electrode of an input amplifier in the laser driver respectively, the differential driver is used for converting the CMOS single-end level signal into an LVDS differential signal, and the LVDS differential signal is used for outputting the LVDS differential signal. And the laser driver is a laser driver supporting differential signal input so as to output the laser driving signal based on the LVDS differential signal. The embodiment of the utility model can ensure the stability of long-distance signal transmission.

Description

Technical Field

[0001] The embodiments of the present utility model relate to the technical field of TOF cameras, and in particular, to a frequency modulation circuit for a TOF camera. Background Art

[0002] A ToF camera is a 3D vision sensor using Time of Flight technology. It emits laser light to an object through a VCSEL laser installed inside, measures the time from the camera to the object, and then calculates the distance between the camera and the object. When a ToF camera is working, it usually needs to use a frequency modulation circuit to adjust the emission frequency of the VCSEL laser to adjust the detection accuracy of the camera.

[0003] An existing frequency modulation circuit for a TOF camera mainly consists of an RX module and a TX module. Among them, the RX module includes a TOF sensor for outputting a CMOS single-ended level signal with a predetermined modulation frequency; the TX module includes a laser driver connected to the TOF sensor for outputting a laser drive signal based on the CMOS single-ended level signal, and a VCSEL laser connected to the laser driver for adjusting the emission frequency under the drive of the laser drive signal.

[0004] However, the inventor found during specific implementation that since the RX module and the TX module in the traditional circuit are usually connected by a board-to-board connector, and the distance between the RX module and the TX module is relatively long, the CMOS single-ended level signal emitted by the TOF sensor of the RX module is prone to being interfered by the outside world during long-distance transmission, resulting in waveform distortion and distortion, ultimately affecting the depth ranging accuracy of the TOF camera. Summary of the Utility Model

[0005] The technical problem to be solved by the embodiments of the present utility model is to provide a frequency modulation circuit for a TOF camera, which can ensure the stability of long-distance signal transmission.

[0006] To solve the above technical problem, the embodiments of the present utility model provide the following technical solutions: A frequency modulation circuit for a TOF camera, comprising:

[0007] An RX module, including a TOF sensor for outputting a CMOS single-ended level signal with a predetermined modulation frequency; and

[0008] A TX module, including a laser driver connected to the TOF sensor for outputting a laser drive signal, and a VCSEL laser connected to the laser driver for adjusting the emission frequency under the drive of the laser drive signal;

[0009] The RX module further includes:

[0010] A differential driver, wherein a single-ended signal input terminal of the differential driver is connected to the TOF sensor, and two differential signal output terminals are respectively connected to the positive and negative electrodes of an input amplifier inside the laser driver. The differential driver is configured to convert the CMOS single-ended level signal into an LVDS differential signal, and the laser driver is a laser driver that supports differential signal input to output the laser driving signal based on the LVDS differential signal.

[0011] Furthermore, the laser driver is an integrated laser driver.

[0012] Furthermore, the TX module further includes a switching transistor S. Herein, the positive electrode of the VCSEL laser is connected to an external power supply, and the negative electrode is connected to the input terminal of the switching transistor S. The output terminal of the switching transistor S is connected to the ground terminal.

[0013] Furthermore, the switching transistor S is integrated inside the laser driver.

[0014] Furthermore, the TOF sensor and the differential driver in the RX module are integrally arranged on a first PCB board.

[0015] Furthermore, the laser driver and the VCSEL laser in the TX module are integrally arranged on a second PCB board.

[0016] Furthermore, the first PCB board and the second PCB board are connected by a board-to-board connector.

[0017] After adopting the above technical solution, the embodiment of the present utility model has at least the following beneficial effects: By adding a differential driver, the embodiment of the present utility model uses the differential driver to convert the CMOS single-ended level signal output by the TOF sensor into an LVDS differential signal. Since the LVDS differential signal has strong anti-interference ability and can support high-speed long-distance signal transmission, a laser driver that supports differential signal input is correspondingly selected to output the laser driving signal based on the LVDS differential signal, thereby ensuring the drive control of the VCSEL laser. Description of the Drawings

[0018] Figure 1 It is a circuit schematic diagram of an optional embodiment of the frequency modulation circuit of the TOF camera of the present utility model. Detailed Embodiments

[0019] The present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following illustrative embodiments and descriptions are only used to explain the present utility model and are not intended to limit the present utility model. Moreover, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0020] As Figure 1 shown, an alternative embodiment of the present utility model provides a frequency modulation circuit for a TOF camera, including:

[0021] RX module 1, including a TOF sensor 10 for outputting a CMOS single-ended level signal of a predetermined modulation frequency; and

[0022] TX module 3, including a laser driver 30 connected to the TOF sensor 10 for outputting a laser drive signal and a VCSEL laser 32 connected to the laser driver 30 for adjusting the emission frequency under the drive of the laser drive signal;

[0023] The RX module 1 further includes:

[0024] A differential driver 12, the single-ended signal input terminal of the differential driver 12 is connected to the TOF sensor 10, and the two differential signal output terminals are respectively connected to the positive and negative electrodes of an input amplifier 301 inside the laser driver 30. The differential driver 12 is used to convert the CMOS single-ended level signal into an LVDS differential signal, and the laser driver 30 is a laser driver supporting differential signal input to output the laser drive signal based on the LVDS differential signal.

[0025] In the embodiment of the present utility model, by adding a differential driver 12, the differential driver 12 is used to convert the CMOS single-ended level signal output by the TOF sensor 10 into an LVDS differential signal. Since the LVDS differential signal has strong anti-interference ability and can support high-speed long-distance signal transmission, the laser driver 30 correspondingly selects a laser driver 30 that can support differential signal input to output the laser drive signal based on the LVDS differential signal, thereby ensuring the drive control of the VCSEL laser 32.

[0026] In an alternative embodiment of the present utility model, the laser driver 30 is an integrated laser driver. In this embodiment, the integrated laser driver 30 is selected for the laser driver 30, and the circuit structure is simpler compared with the traditional discrete laser driver.

[0027] In an alternative embodiment of the present utility model, as Figure 1As shown, a switching transistor S is integrated inside the laser driver 30. Among them, the positive electrode of the VCSEL laser 32 is connected to an external power supply 5, and the negative electrode is connected to the input end of the switching transistor S. The output end of the switching transistor S is connected to the ground terminal. In this embodiment, a laser driver 30 with a switching transistor S integrated inside is directly adopted, and the circuit structure is simpler. Inside the laser driver 30, the laser driving signal controls the on / off of the switching transistor S, and thus the emission frequency control of the VCSEL laser 32 can be quickly achieved. In a specific implementation, the switching transistor S can be a triode or a MOS transistor. In Figure 1 it is a MOS transistor, and the corresponding input end is the source electrode, and the output end is the drain electrode.

[0028] In an alternative embodiment of the present invention, as Figure 1 shown, the switching transistor S is integrated inside the laser driver 30. In this embodiment, a laser driver with the switching transistor S integrated inside is selected for the laser driver 30, which simplifies the circuit structure.

[0029] In an alternative embodiment of the present invention, as Figure 1 shown, the TOF sensor 10 and the differential driver 12 in the RX module 1 are integrally arranged on a first PCB board 14. In this embodiment, assembling each circuit device in the RX module 1 on the first PCB board 14 is beneficial to simplifying the circuit structure.

[0030] In an alternative embodiment of the present invention, as Figure 1 shown, the laser driver 30 and the VCSEL laser 32 in the TX module 3 are integrally arranged on a second PCB board 34. In this embodiment, assembling each circuit device in the TX module 3 on the second PCB board 34 is beneficial to simplifying the circuit structure.

[0031] In an alternative embodiment of the present invention, as Figure 1 shown, the first PCB board 14 and the second PCB board 34 are connected by a board-to-board connector 7 (B2B connector). In this embodiment, using the board-to-board connector 7 to connect the first PCB board 14 and the second PCB board 34 can quickly realize the connection between the differential driver 12 and the laser driver 30, and can ensure the stable transmission of signals.

[0032] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above specific implementation manners. The above specific implementation manners are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the purpose of the present invention and the scope protected by the claims. These all fall within the protection scope of the present invention.

Claims

1. A frequency modulation circuit for a TOF camera, comprising: an RX module, including a TOF sensor for outputting a CMOS single-ended level signal of a predetermined modulation frequency; and a TX module, including a laser driver connected to the TOF sensor for outputting a laser driving signal and a VCSEL laser connected to the laser driver for adjusting the emission frequency under the drive of the laser driving signal; characterized in that the RX module further includes: a differential driver, the single-ended signal input terminal of the differential driver is connected to the TOF sensor, and the two differential signal output terminals are respectively connected to the positive and negative electrodes of the input amplifier inside the laser driver. The differential driver is used to convert the CMOS single-ended level signal into an LVDS differential signal, and the laser driver is a laser driver supporting differential signal input to output the laser driving signal based on the LVDS differential signal.

2. The frequency modulation circuit of the TOF camera according to claim 1, characterized in that The laser driver is an integrated laser driver.

3. The frequency modulation circuit of the TOF camera according to claim 2, characterized in that, The TX module further includes a switching transistor S. Among them, the positive electrode of the VCSEL laser is connected to an external power supply, the negative electrode is connected to the input terminal of the switching transistor S, and the output terminal of the switching transistor S is connected to the ground terminal.

4. The frequency modulation circuit of the TOF camera according to claim 3, characterized in that, The switching transistor S is integrated inside the laser driver.

5. The frequency modulation circuit of the TOF camera according to claim 1, characterized in that, The TOF sensor and the differential driver in the RX module are integrally arranged on a first PCB board.

6. The frequency modulation circuit of the TOF camera according to claim 5, characterized in that The laser driver and the VCSEL laser in the TX module are integrally arranged on a second PCB board.

7. The frequency modulation circuit of the TOF camera according to claim 6, characterized in that, The first PCB board is connected to the second PCB board through a board-to-board connector.

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