Vehicle-mounted camera and safety protection circuit thereof

Abstract

The embodiment of the utility model provides a vehicle-mounted camera and a safety protection circuit thereof, and the circuit is respectively connected with a laser driver of the vehicle-mounted camera and a driving loop of a VCSEL laser. Comprising a first MOS transistor N1, a second MOS transistor N2 and a photodiode PD, the photodiode PD is arranged in a laser cavity of the VCSEL laser and used for being correspondingly conducted when light exists in the laser cavity, a grid electrode of the first MOS transistor N1 is connected to a driving pin of a laser driver, a source electrode of the first MOS transistor N1 is connected to a grounding end, and a drain electrode of the first MOS transistor N1 is connected to a source electrode of the second MOS transistor N2; the grid electrode of the second MOS transistor N2 is connected to the positive electrode of the photodiode PD, is connected to the grounding end through the first resistor R1, and is connected to the driving pin of the laser driver through the capacitor C, and the drain electrode of the second MOS transistor N2 is connected to the driving loop of the VCSEL laser; and the negative electrode of the photodiode PD is connected to an external power supply VCC. According to the embodiment, when the light diffusion sheet falls off, the human body can be effectively prevented from being hurt by laser.

Description

Technical Field

[0001] The embodiments of the utility model relate to the technical field of camera circuits, and in particular to a vehicle-mounted camera and a safety protection circuit thereof. Background Art

[0002] In order to effectively monitor the status of the driver and passengers and ensure that clear images can be captured under different lighting conditions, the on-board camera installed in the passenger compartment is usually equipped with a fill light circuit.

[0003] An existing fill light circuit for an on-board camera mainly includes a main controller, a laser driver connected to the main controller to output a PWM drive signal under the control of the main controller, and a drive circuit connected to the laser driver and equipped with a VCSEL laser. The laser driver outputs a PWM drive signal through a drive pin to drive the VCSEL laser to emit infrared light to achieve fill light. Among them, the VCSEL laser, as an infrared light-emitting device, mainly includes a base with a laser cavity and an open top, a laser-type light-emitting chip assembled in the laser cavity of the base, and a light diffuser covering the top opening of the base. Its working principle is: the laser generated by the light-emitting chip is diffused and emitted through the light diffuser, and the light diffuser also refracts the laser and reflects it in the laser cavity.

[0004] However, during the specific implementation, the inventors found that when the light diffuser falls off, the laser generated by the light-emitting chip is directly emitted without being diffused, which can cause great harm to the human body (especially the eyes). Therefore, a safety protection circuit is urgently needed to automatically shut down the VCSEL laser when the light diffuser falls off. Utility Model Content

[0005] The technical problem to be solved by the embodiments of the present utility model is to provide a safety protection circuit for a vehicle-mounted camera, which can effectively prevent laser from harming the human body when a light diffusion sheet falls off.

[0006] A further technical problem to be solved by the embodiments of the present invention is to provide a vehicle-mounted camera that can effectively prevent laser damage to the human body when the light diffusion sheet falls off.

[0007] To solve the above technical problems, the present invention first provides the following technical solutions: a safety protection circuit for an on-board camera, connected to the laser driver of the on-board camera and the drive circuit of a VCSEL laser, respectively, including a first MOS transistor N1, a second MOS transistor N2, and a photodiode PD disposed in a laser cavity of the VCSEL laser and configured to be turned on when detecting the presence of light in the laser cavity, wherein:

[0008] The gate of the first MOS transistor N1 is connected to the driving pin of the laser driver, the source of the first MOS transistor N1 is connected to the ground terminal, and the drain of the first MOS transistor N1 is connected to the source of the second MOS transistor N2;

[0009] The gate of the second MOS transistor N2 is connected to the positive electrode of the photodiode PD, and is connected to the ground terminal through the first resistor R1, and is also connected to the driving pin of the laser driver through the capacitor C. The drain of the second MOS transistor N2 is connected to the driving circuit of the VCSEL laser;

[0010] The cathode of the photodiode PD is connected to an external power supply VCC.

[0011] Furthermore, the safety protection circuit includes a plurality of photodiodes PD arranged in one-to-one correspondence with each VCSEL laser in the driving circuit, and the plurality of photodiodes PD are connected in series in sequence to form a first series body, wherein the cathode of the photodiode PD located on the upstream side of the first series body is connected to the anode of the photodiode PD adjacent to the downstream side of the first series body, the anode of the first photodiode PD on the upstream side of the first series body serves as the input end of the first series body and is respectively connected to the gate of the second MOS tube N2, the first resistor R1 and the capacitor C, and the cathode of the last photodiode PD on the downstream side of the first series body serves as the output end of the first series body and is connected to the external power supply VCC.

[0012] Furthermore, the drain of the second MOS transistor N2 is connected to the driving circuit of the VCSEL laser through a second resistor R2.

[0013] On the other hand, in order to solve the above-mentioned further technical problems, the embodiments of the present invention further provide the following technical solutions: A vehicle-mounted camera, comprising a laser driver for outputting a PWM drive signal, a drive circuit connected to the laser driver and provided with a VCSEL laser, and a safety protection circuit respectively connected to the laser driver and the drive circuit, wherein the safety protection circuit is the above-mentioned safety protection circuit.

[0014] Furthermore, a plurality of the VCSEL lasers are provided in the driving circuit, and the plurality of VCSEL lasers are connected in series in sequence to form a second series body, wherein the cathode of the VCSEL laser located on the upstream side of the second series body is connected to the anode of the adjacent VCSEL laser on the downstream side of the second series body, and the anode of the first VCSEL laser on the upstream side of the second series body and the cathode of the last VCSEL laser on the downstream side of the second series body are respectively connected to the driving circuit.

[0015] Furthermore, the vehicle-mounted camera also includes a main controller connected to the laser driver for controlling the laser driver to output a PWM drive signal.

[0016] After adopting the above technical solution, the embodiment of the present invention has at least the following beneficial effects: the embodiment of the present invention includes a first MOS transistor N1, a second MOS transistor N2 and a photodiode PD. When the light diffuser of the VCSEL laser is not detached and is working normally, the laser driver outputs a PWM drive signal through the drive pin, the first MOS transistor N1 and the second MOS transistor N2 are normally turned on, the light diffuser refracts the light so that the photodiode PD detects the presence of light in the laser cavity of the laser driver and turns on, so that the first MOS transistor N1 and the second MOS transistor N2 remain turned on, and the VCSEL laser continuously and stably fills the light. In order to avoid the low level period of the VCSEL laser after the first pulse cycle of the PWM drive signal ends, The VCSEL laser does not emit light, causing the photodiode PD to be disconnected, making the circuit unable to work properly. By setting the capacitor C to provide a small pulse during the rising edge of the second pulse cycle of the PWM drive signal, the second MOS tube N2 is activated to turn on instantly, thereby making the VCSEL laser emit light. At this time, the photodiode PD remains turned on, thereby ensuring the smooth turning on of the subsequent second MOS tube N2. When the light diffuser of the VCSEL laser falls off abnormally, the laser generated by the VCSEL laser is directly emitted and cannot turn on the photodiode PD. Then the first MOS tube N1 and the second MOS tube N2 are turned off, and finally the driving circuit of the VCSEL laser is disconnected, thereby stopping the laser emission to avoid harm to the human body. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a circuit diagram of an optional embodiment of the vehicle-mounted camera of the utility model. DETAILED DESCRIPTION

[0018] The present application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the following exemplary embodiments and descriptions are only used to explain the present invention and are not intended to limit the present invention. Moreover, the embodiments and features in the embodiments of the present application may be combined with each other unless there is a conflict.

[0019] like Figure 1 As shown, an optional embodiment of the present invention provides a safety protection circuit 1 for a vehicle-mounted camera, which is connected to a laser driver 3 of the vehicle-mounted camera and a drive circuit 5 of a VCSEL laser 50, respectively. The circuit includes a first MOS transistor N1, a second MOS transistor N2, and a photodiode PD disposed in a laser cavity of the VCSEL laser 50 and turned on when detecting the presence of light in the laser cavity.

[0020] The gate of the first MOS transistor N1 is connected to the driving pin of the laser driver 3 (see Figure 1 The source of the first MOS transistor N1 is connected to the ground terminal, and the drain of the first MOS transistor N1 is connected to the source of the second MOS transistor N2;

[0021] The gate of the second MOS transistor N2 is connected to the anode of the photodiode PD, and is connected to the ground terminal through the first resistor R1, and is also connected to the driving pin of the laser driver 3 through the capacitor C. The drain of the second MOS transistor N2 is connected to the driving circuit of the VCSEL laser 50;

[0022] The cathode of the photodiode PD is connected to an external power supply VCC.

[0023] The embodiment of the utility model includes a first MOS transistor N1, a second MOS transistor N2 and a photodiode PD (the photodiode PD is turned on by default at the moment of power-on). When the light diffuser of the VCSEL laser 50 is not detached and is operating normally, the laser driver 3 outputs a PWM drive signal through the drive pin, the first MOS transistor N1 and the second MOS transistor N2 are normally turned on, the light diffuser refracts the light so that the photodiode PD detects the presence of light in the laser cavity of the laser driver 3 and turns on, so that the first MOS transistor N1 and the second MOS transistor N2 remain turned on, and the VCSEL laser 50 continuously and stably fills the light. In order to avoid the VCSEL laser 50 not being in the low level period after the first pulse cycle of the PWM drive signal ends, The light emission causes the photodiode PD to be disconnected, making the circuit unable to work properly. By setting the capacitor C to provide a small pulse during the rising edge of the second pulse cycle of the PWM drive signal, the second MOS transistor N2 is activated to turn on instantly, thereby making the VCSEL laser 50 emit light. At this time, the photodiode PD remains on, thereby ensuring the smooth turning on of the second MOS transistor N2 later. When the light diffuser of the VCSEL laser 50 falls off abnormally, the laser generated by the VCSEL laser 50 is directly emitted and cannot turn on the photodiode PD. Then the first MOS transistor N1 and the second MOS transistor N2 are turned off, and finally the driving circuit of the VCSEL laser 50 is disconnected, thereby stopping the laser emission and avoiding harm to the human body.

[0024] In an optional embodiment of the present invention, Figure 1As shown, the safety protection circuit 1 includes a plurality of photodiodes PD, each corresponding to each VCSEL laser 50 in the drive circuit 5. The plurality of photodiodes PD are sequentially connected in series to form a first series body, wherein the cathode of the photodiode PD located on the upstream side of the first series body is connected to the anode of the adjacent photodiode PD on the downstream side of the first series body. The anode of the first photodiode PD on the upstream side of the first series body is respectively connected to the gate of the second MOS transistor N2, the first resistor R1, and the capacitor C. The cathode of the last photodiode PD on the downstream side of the first series body is connected to the external power supply VCC. Typically, multiple VCSEL lasers 50 are installed in an on-board camera. Accordingly, in this embodiment, a photodiode PD is provided in each VCSEL laser 50, thereby enabling detection of each VCSEL laser 50 and effectively achieving safety protection.

[0025] In an optional embodiment of the present invention, Figure 1 As shown, the drain of the second MOS transistor N2 is connected to the drive circuit 5 of the VCSEL laser 50 through the second resistor R2. In this embodiment, by connecting the drain of the second MOS transistor N2 to the drive circuit of the VCSEL laser 50 through the second resistor R2, the second MOS transistor N2 is effectively protected.

[0026] On the other hand, Figure 1 As shown, another embodiment of the present invention provides an in-vehicle camera, comprising a laser driver 3 for outputting a PWM drive signal, a drive circuit 5 connected to the laser driver 3 and equipped with a VCSEL laser 50, and a safety protection circuit 1 respectively connected to the laser driver 3 and the drive circuit. The safety protection circuit 1 can be any of the safety protection circuits described above. In this embodiment, the in-vehicle camera utilizes the aforementioned safety protection circuit to promptly stop laser emission if the light diffuser of the VCSEL laser 50 falls off, effectively preventing harm to the human body.

[0027] In an optional embodiment of the present invention, Figure 1As shown, the drive circuit 5 is provided with a plurality of VCSEL lasers 50, which are sequentially connected in series to form a second series body, wherein the cathode of the VCSEL laser 50 located on the upstream side of the second series body is connected to the anode of the adjacent VCSEL laser 50 on the downstream side of the second series body, and the anode of the first VCSEL laser 50 on the upstream side of the second series body and the cathode of the last VCSEL laser 50 on the downstream side of the second series body are respectively connected to the drive circuit 5. In this embodiment, a plurality of VCSEL lasers 50 are provided in the drive circuit 5 of the vehicle-mounted camera, and the plurality of VCSEL lasers 50 jointly realize fill light.

[0028] In an optional embodiment of the present invention, Figure 1 As shown, the vehicle-mounted camera further includes a main controller 7 connected to the laser driver 3 for controlling the laser driver 3 to output a PWM drive signal. In this embodiment, the main controller 7 is also provided to facilitate the vehicle-mounted camera to control parameters such as the timing and brightness of the fill light. For details, see Figure 1 Specifically, the main controller 7 outputs a PWM control signal to the PWM pin of the VCSEL driver 3, thereby controlling the VCSEL driver 3 to output a PWM driving signal with a matching duty cycle through the driving pin (DIMOUT).

[0029] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, which all fall within the scope of protection of the present invention.

Claims

1. A safety protection circuit for a vehicle-mounted camera, connected to the laser driver of the vehicle-mounted camera and the drive circuit of a VCSEL laser, characterized in that: The safety protection circuit includes a first MOS transistor N1, a second MOS transistor N2, and a photodiode PD disposed in the laser cavity of the VCSEL laser and configured to be turned on when detecting the presence of light in the laser cavity, wherein: The gate of the first MOS transistor N1 is connected to the driving pin of the laser driver, the source of the first MOS transistor N1 is connected to the ground terminal, and the drain of the first MOS transistor N1 is connected to the source of the second MOS transistor N2; The gate of the second MOS transistor N2 is connected to the positive electrode of the photodiode PD, and is connected to the ground terminal through the first resistor R1, and is also connected to the driving pin of the laser driver through the capacitor C. The drain of the second MOS transistor N2 is connected to the driving circuit of the VCSEL laser; The cathode of the photodiode PD is connected to an external power supply VCC.

2. The safety protection circuit of the vehicle-mounted camera according to claim 1, characterized in that: The safety protection circuit includes a plurality of photodiodes PD arranged in one-to-one correspondence with each VCSEL laser in the drive circuit. The plurality of photodiodes PD are connected in series in sequence to form a first series body, wherein the cathode of the photodiode PD located on the upstream side of the first series body is connected to the anode of the adjacent photodiode PD on the downstream side. The anode of the first photodiode PD on the upstream side of the first series body serves as the input end of the first series body and is respectively connected to the gate of the second MOS tube N2, the first resistor R1 and the capacitor C. The cathode of the last photodiode PD on the downstream side of the first series body serves as the output end of the first series body and is connected to the external power supply VCC.

3. The safety protection circuit of the vehicle-mounted camera according to claim 1, characterized in that: The drain of the second MOS transistor N2 is connected to the driving circuit of the VCSEL laser through a second resistor R2.

4. A vehicle-mounted camera, comprising a laser driver for outputting a PWM drive signal, a drive circuit connected to the laser driver and provided with a VCSEL laser, and a safety protection circuit respectively connected to the laser driver and the drive circuit, characterized in that: The safety protection circuit is the safety protection circuit according to any one of claims 1 to 3.

5. The vehicle-mounted camera according to claim 4, wherein: A plurality of VCSEL lasers are provided in the driving circuit, and the plurality of VCSEL lasers are connected in series in sequence to form a second series body, wherein the cathode of the VCSEL laser located on the upstream side of the second series body is connected to the anode of the adjacent VCSEL laser on the downstream side, and the anode of the first VCSEL laser on the upstream side of the second series body and the cathode of the last VCSEL laser on the downstream side of the second series body are respectively connected to the driving circuit.

6. The vehicle-mounted camera according to claim 4, wherein: The vehicle-mounted camera further comprises a main controller connected to the laser driver and used for controlling the laser driver to output a PWM driving signal.

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