Laser control circuit and control method thereof

Abstract

The present disclosure relates to the technical field of laser, and provides a laser control circuit and a control method thereof. The laser control circuit comprises an analog switch, an enable input control end of the analog switch being connected with a PWM signal input port, a signal input end of the analog switch being connected with an analog signal input port, and the analog switch being used for outputting or cutting off an analog input signal according to a PWM signal; a first switch tube, a control end of the first switch tube being connected with the PWM signal input port, and the first switch tube being used for controlling current output of a current output end of the first switch tube according to a voltage signal of the control end; a current controller, an analog frequency multiplexing port of the current controller being connected with a signal output end of the analog switch, and the current controller being used for controlling a size and a time sequence of output current according to the PWM signal and the analog input signal; and a laser control output port, the laser control output port being connected with a current output end of the current controller, and the laser control output port being used for controlling a brightness and a time sequence of laser output by a laser according to the output current.

Description

Technical Field

[0001] This disclosure relates to the field of laser technology, and in particular to a laser control circuit and its control method. Background Technology

[0002] In related technologies, laser dimming circuits can use current controller chips as the main components to adjust the magnitude and timing of the control current input to the laser, thereby controlling the intensity and timing of the laser beam generated by the laser.

[0003] Due to the limited number of pins on the current controller chip, the current controller chip uses an analog frequency conversion multiplexing pin to receive control signals for analog or timing control of the current controller. As a result, when using the current controller chip for laser dimming, only one of the following modes can be selected: PWM (Pulse Width Modulation) dimming mode or analog dimming mode.

[0004] In practical applications, laser dimming may require simultaneous adjustment of both laser intensity and timing, meaning adjustments to both the magnitude and frequency (timing) of the control current input to the laser. How to simultaneously adjust both laser intensity and timing using existing current controller chips is a pressing technical problem that needs to be solved. Summary of the Invention

[0005] In view of this, the present disclosure provides a laser control circuit and control method thereof to solve the problem that the current controller in the prior art cannot simultaneously adjust the magnitude and timing of the output current.

[0006] To achieve the above objectives, the technical solution adopted in this disclosure is:

[0007] On one hand, this disclosure provides a laser control circuit, which includes: an input port, including a pulse width modulation (PWM) signal input port and an analog signal input port; an analog switch, wherein the enable input control terminal of the analog switch is connected to the PWM signal input port, and the signal input terminal of the analog switch is connected to the analog signal input port, for outputting or cutting off the analog input signal according to the PWM signal; a first switching transistor, wherein the control terminal of the first switching transistor is connected to the PWM signal input port, the current input terminal of the first switching transistor is connected to the analog signal input port, and the current output terminal of the first switching transistor is connected to the signal output terminal of the analog switch, for controlling the current output of the current output terminal of the first switching transistor according to the voltage signal of the control terminal; a current controller, including an analog frequency conversion multiplexing port, wherein the analog frequency conversion multiplexing port is connected to the signal output terminal of the analog switch, for controlling the magnitude and timing of the output current according to the PWM signal and the analog input signal; and a laser control output port, connected to the current output terminal of the current controller, for controlling the brightness and timing of the laser output by the laser according to the output current.

[0008] In one embodiment, the current controller uses a chip of model MP24894.

[0009] In one embodiment, the analog switch uses a chip of model RS2166.

[0010] In one embodiment, the first switching transistor is an N-type metal-oxide-semiconductor (NMOS) transistor.

[0011] In one embodiment, the laser control circuit further includes a buck drive circuit connected between the current controller and the laser control output port. The buck drive circuit includes a first capacitor, a first inductor, a first diode, and a second switching transistor constituting a BUCK circuit. The first output terminal of the current controller is connected to the first capacitor, the second output terminal of the current controller is connected to the control terminal of the second switching transistor, and the two ends of the laser control output port are respectively connected to the two ends of the first capacitor.

[0012] In one embodiment, the second switching transistor includes an NMOS transistor.

[0013] In one embodiment, the laser control circuit further includes an output filter circuit connected between the first output terminal of the current controller and ground, and the output filter circuit includes a second capacitor.

[0014] In one embodiment, the laser control circuit further includes an input filter circuit connected between the signal output terminal of the analog switch and the analog frequency conversion multiplexing port of the current controller. The input filter circuit includes a third capacitor and a third resistor connected in parallel.

[0015] In one embodiment, a set of input ports is connected to a corresponding laser control output port. The laser control circuit includes three sets of input ports and three corresponding laser control output ports, which are used to control three lasers of different colors respectively.

[0016] On the other hand, this disclosure provides a control method applied to the aforementioned laser control circuit. The laser control method includes: controlling the on / off state of an analog switch and a first switching transistor by adjusting the timing of a PWM signal and the magnitude of an analog input signal, so that the current controller controls the magnitude and timing of the output current according to the PWM signal and the analog input signal, so as to control the brightness and timing of the laser output by the laser according to the output current.

[0017] The beneficial effects of this disclosed embodiment compared with the prior art are as follows: by adjusting the PWM signal and the analog input signal and inputting the PWM signal and the analog input signal into the analog switch and the first switching transistor, the enable input control signal of the current controller is obtained, so that the current controller outputs the laser control current under the control of the enable input control signal, thereby simultaneously controlling the brightness and timing of the laser output, and improving the performance of the laser control circuit. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of the laser control circuit provided in the embodiments of this disclosure;

[0020] Figure 2 This is a circuit diagram of the laser control circuit provided in an embodiment of this disclosure;

[0021] Figure 3 This is a schematic diagram of the current direction when the NMOS is turned on, provided in an embodiment of this disclosure;

[0022] Figure 4 This is a schematic flowchart of the control method for the laser control circuit provided in the embodiments of this disclosure. Detailed Implementation

[0023] To make the technical problems, technical solutions, and beneficial effects to be solved by this disclosure clearer, the disclosure will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining this disclosure and are not intended to limit this disclosure.

[0024] The laser control circuit and control method according to embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.

[0025] Figure 1 This is a schematic diagram of the structure of the laser control circuit provided in the embodiments of this disclosure; Figure 2 This is a circuit diagram of the laser control circuit provided in the embodiments of this disclosure; the following is in conjunction with... Figure 1 and Figure 2 Let's describe the laser control circuit provided in the embodiments of this disclosure.

[0026] like Figure 1 As shown, this disclosure provides a laser control circuit, which includes:

[0027] The input ports include a PWM signal input port 101 and an analog signal input port 102.

[0028] Specifically, the PWM signal input at PWM signal input port 101 is generated by a PWM signal source, which can be a single-chip microcontroller, but is not limited to this. The analog input signal input at analog signal input port 102 is generated by an analog signal source, which can be a single-chip microcontroller, but is not limited to this.

[0029] Analog switch 111 has its enable input control terminal connected to the PWM signal input port and its signal input terminal connected to the analog signal input port. It is used to output or cut off the analog input signal according to the PWM signal.

[0030] Specifically, the PWM signal is input to the enable input control terminal of the analog switch. When the PWM signal is a high-level voltage, the signal output terminal of the analog switch can output the analog input signal input to the signal input terminal of the analog switch, that is, the analog input signal input to the analog signal input port 102. When the PWM signal is a low level, the signal output terminal of the analog switch can not output the analog input signal input to the signal input terminal of the analog switch.

[0031] The first switching transistor 112 has its control terminal connected to the PWM signal input port, its current input terminal connected to the analog signal input port, and its current output terminal connected to the signal output terminal of the analog switch. It is used to control the current output of the current output terminal of the first switching transistor according to the voltage signal of the control terminal.

[0032] Specifically, the PWM signal is input to the gate of the first switching transistor. When the PWM signal is a high-level voltage, the current output terminal of the first switching transistor can output the current corresponding to the analog input signal input at the current input terminal, that is, the current corresponding to the analog input signal input at the analog signal input port 102. When the PWM signal is a low level, the current output terminal of the first switching transistor can not output current.

[0033] The current controller 113 includes an analog frequency converter multiplexing port, which is connected to the signal output terminal of an analog switch and is used to control the magnitude and timing of the output current according to the PWM signal and the analog input signal.

[0034] Specifically, since the current output terminal of the first switching transistor is connected to the signal output terminal of the analog switch, it can be known that the analog frequency conversion multiplexing port is connected to the signal output terminal of the analog switch and the current output terminal of the first switching transistor, thereby enabling the analog frequency conversion multiplexing port of the current controller to receive the superposition of the signals from the signal output terminal of the analog switch and the current output terminal of the first switching transistor.

[0035] When the PWM signal is a high-level voltage, the signal output terminal of the analog switch outputs the analog input signal input through analog signal input port 102, and the current output terminal of the first switching transistor outputs the current corresponding to the analog input signal input through the current input terminal. When the PWM signal is a low-level voltage, the signal output terminal of the analog switch does not output the analog input signal input through analog signal input port 102, and the current output terminal of the first switching transistor does not output current.

[0036] It can be seen that by superimposing the signals from the signal output terminal of the analog switch and the current output terminal of the first switching transistor, the enable input control signal of the current controller, which is adjusted according to the timing data such as the duty cycle of the PWM signal and the magnitude of the analog input signal, can be obtained. In turn, the output current of the current controller changes according to the timing of the PWM signal and the magnitude of the analog input signal.

[0037] The laser control output port 103 is connected to the current output terminal of the current controller and is used to control the brightness and timing of the laser output by the laser according to the output current.

[0038] Specifically, the laser control output port 103 can output a current to the laser that varies according to the timing of the PWM signal and the magnitude of the analog input signal, thereby controlling the brightness and timing of the laser output.

[0039] According to the laser control circuit provided in the embodiments of this disclosure, the timing of the laser-generating current is controlled by adjusting the timing data such as the duty cycle of the PWM signal, and the magnitude of the laser-generating current is controlled by adjusting the output of the analog control voltage signal. Thus, the timing and magnitude of the laser-generating current are controlled simultaneously, thereby enabling simultaneous control of the laser's timing and brightness, and improving the performance of the laser control circuit.

[0040] In this embodiment of the disclosure, the current controller can be a chip of model MP24894. For example... Figure 2 As shown, chip U2 is MP24894. Its pin 3 is the analog frequency conversion multiplexing pin EN / DIM corresponding to the analog frequency conversion multiplexing port, pin 1 is the pin IN corresponding to the input terminal of the current controller, pin 2 is the pin RS corresponding to the first output terminal of the current controller, and pin 5 is the pin DR corresponding to the second output terminal of the current controller.

[0041] The MP24894 is a buck current controller that can power high-brightness LEDs or lasers (laser sources) in continuous current mode. The MP24894 features a wide input voltage range of 6V to 60V and a low average feedback voltage of 200mV, thereby reducing power loss and improving the efficiency of the voltage converter.

[0042] From a packaging perspective, the MP24894 uses a TSOT-6 package, which is a 6-pin TSOT (Thin Small Outline Transistor) package. This leadframe-based plastic package is specifically designed for applications requiring extremely small footprint. When powering high-brightness LEDs or lasers, the MP24894's analog frequency conversion multiplexed pins, namely the EN / DIM pins, can provide PWM or analog dimming functions. By multiplexing pins, the MP24894 reduces the number of pins required.

[0043] In this embodiment of the disclosure, the analog switch can be a chip of model RS2166. For example... Figure 2 As shown, chip U1 is RE2166. Its pin 4 is the enable input control pin SEL, pin 1 is the analog signal input pin S, and pin 2 is the analog signal output pin D, which corresponds to the signal output terminal of the analog switch.

[0044] The RS2166 is a bidirectional, single-channel, single-pole, single-throw analog switch designed to operate between 1.8V and 5.5V. The RS2166 can handle both analog and digital signals. Each switching section has its own enable input control; a high-level voltage applied to the enable input control pin turns on the corresponding switching section. In this embodiment, the RS2166 controls analog signals based on the digital signal input to the enable input control pin. When the digital signal input to the enable input control pin is a high-level voltage, the analog signal input pin and analog signal output pin of the analog switch are turned on, and the analog signal output pin outputs the analog input signal input to the analog signal input pin.

[0045] like Figure 2 As shown, in this embodiment of the disclosure, the first switch Q1 can be an NMOS (N-Metal-Oxide-Semiconductor) transistor. An NMOS transistor conducts when the gate is at a high voltage level and is turned off when the gate is at a low voltage level, and can be used to control the conduction between the source and drain. Figure 2 As shown, when the gate voltage (G) is higher than the source voltage (S), the NMOS is turned on, and current flows from the drain (D) to the source (S). When the gate voltage (G) is not higher than the source voltage (S), the NMOS is not turned on, and there is no current flowing from the drain (D) to the source (S). Specifically, when the gate voltage (G) is higher than the source voltage (S), the current direction when the NMOS is turned on is as follows: Figure 3 As shown by the arrow in the image.

[0046] In this embodiment of the disclosure, the laser control circuit may further include a buck driver circuit connected between the current controller and the laser control output port. Figure 2 As shown, the buck driver circuit includes a first capacitor C5, a first inductor L1, a first diode D1, and a second switching transistor Q2, constituting the BUCK circuit. Pin 2 of the first output terminal of the current controller is connected to the first capacitor, and pin 5 of the second output terminal of the current controller is connected to the control terminal of the second switching transistor. The two ends of the laser control output port are respectively connected to the two ends of the first capacitor. Specifically, the second switching transistor Q2 can be an NMOS transistor. This buck driver circuit can adjust the output current to precisely drive the laser.

[0047] In this embodiment of the disclosure, the laser control circuit may further include an output filtering circuit, such as... Figure 2 As shown, the output filter circuit is connected between pin 2 corresponding to the first output terminal of the current controller and ground. The output filter circuit includes a second capacitor C4. The first resistor R2 and the second resistor R4 connected between the input terminal and the first output terminal of the current controller are used for current feedback.

[0048] The MP24894 employs a hysteresis control structure, precisely adjusting the output current through feedback from an external high-side current sensing resistor. This control method, combined with the output filter circuit, optimizes circuit stability.

[0049] In this embodiment of the disclosure, the laser control circuit may further include an input filtering circuit, such as... Figure 2 As shown, the input filter circuit is connected between the signal output terminal of the analog switch and the analog frequency conversion multiplexing port of the current controller. The input filter circuit includes a third capacitor C8 and a third resistor R10 connected in parallel. This input filter circuit can optimize circuit stability.

[0050] In this embodiment of the disclosure, a set of input ports can be connected to a laser control output port. The laser control circuit can include three sets of input ports and three corresponding laser control output ports, which are used to control three lasers of different colors respectively.

[0051] Specifically, by adjusting the PWM signals and analog input signals at the input ports of three different laser control circuits, the three different laser control output ports can output current signals with different timings and amplitudes. With each laser control output port corresponding to a laser light source of a specific color, the color of the output laser from different colors can be controlled simultaneously. For example, the three laser light sources could be red, green, and blue. Furthermore, by adjusting the PWM signals and analog input signals at the input ports of the laser control circuits corresponding to the three different laser light sources, the laser intensity, timing, and color of the three colors of laser light sources can be adjusted simultaneously and separately.

[0052] According to the laser control circuit provided in the embodiments of this disclosure, by adjusting the PWM signal and the analog input signal and inputting the PWM signal and the analog input signal into the analog switch and the first switching transistor, an enable input control signal for the current controller is obtained, so that the current controller outputs the laser control current under the control of the enable input control signal, thereby simultaneously controlling the brightness and timing of the laser output, and improving the performance of the laser control circuit.

[0053] like Figure 4 As shown, this disclosure provides a control method for a laser control circuit, used to control the current of a laser based on the laser control circuit in the above-described technical solution, so as to emit laser light with target intensity and timing. Specifically, the control method for the laser control circuit includes:

[0054] Step S401: By adjusting the timing of the PWM signal and the magnitude of the analog input signal, the on / off state of the analog switch and the first switching transistor is controlled, so that the current controller controls the magnitude and timing of the output current according to the PWM signal and the analog input signal, so as to control the brightness and timing of the laser output by the laser according to the output current.

[0055] Specifically, the switching states of the analog switch and the first switching transistor can be adjusted by adjusting the PWM signal generated by the PWM signal source and the analog input signal generated by the analog signal source.

[0056] When the PWM signal is a high-level voltage, the analog switch's signal output terminal can output the analog input signal input to the analog switch's signal input terminal. When the PWM signal is a low-level voltage, the analog switch's signal output terminal can not output the analog input signal input to the analog switch's signal input terminal.

[0057] When the PWM signal is a high-level voltage, the current output terminal of the first switching transistor can output the current corresponding to the analog input signal input to the current input terminal. When the PWM signal is a low-level voltage, the current output terminal of the first switching transistor can not output current.

[0058] Furthermore, by superimposing the signals from the analog switch's signal output terminal and the first switching transistor's current output terminal, an enable input control signal for the current controller, which adjusts according to timing data such as the duty cycle of the PWM signal and the magnitude of the analog input signal, can be obtained. This, in turn, yields the output current of the current controller, which varies according to the timing of the PWM signal and the magnitude of the analog input signal. By outputting a current to the laser that varies according to the timing of the PWM signal and the magnitude of the analog input signal, the brightness and timing of the laser output can be controlled.

[0059] According to the control method of the laser control circuit provided in the embodiments of this disclosure, the timing of the laser-generating current is controlled by adjusting the timing data such as the duty cycle of the PWM signal, and the magnitude of the laser-generating current is controlled by adjusting the output of the analog control voltage signal. Thus, the timing and magnitude of the laser-generating current are controlled simultaneously, thereby enabling simultaneous control of the laser's timing and brightness, and improving the performance of the laser control circuit.

[0060] In this embodiment, the current controller can be an MP24894 chip. The analog switch can be an RS2166 chip.

[0061] In this embodiment, the first switching transistor can be an NMOS transistor. An NMOS transistor conducts when its gate is at a high voltage level and is turned off when its gate is at a low voltage level, and can be used to control the conduction between the source and drain. In this embodiment, the laser control circuit may further include a buck driver circuit connected between the current controller and the laser control output port. The buck driver circuit includes a first capacitor, a first inductor, a first diode, and a second switching transistor constituting a BUCK circuit, wherein the second switching transistor can be an NMOS transistor. This buck driver circuit can adjust the output current to precisely drive the laser.

[0062] In this embodiment, the laser control circuit may further include an output filter circuit connected between pin 2 corresponding to the first output terminal of the current controller and ground. The output filter circuit includes a second capacitor C4. A first resistor R2 and a second resistor R4 connected between the first output terminal of the current controller and the laser control output port are used for current feedback.

[0063] In this embodiment, the laser control circuit may further include an input filter circuit connected between the signal output terminal of the analog switch and the analog frequency conversion multiplexing port of the current controller. The input filter circuit includes a third capacitor and a third resistor connected in parallel. This input filter circuit can optimize circuit stability.

[0064] In this embodiment of the disclosure, a set of input ports can be connected to a laser control output port. The laser control circuit can include three sets of input ports and three corresponding laser control output ports, which are used to control three lasers of different colors respectively.

[0065] Specifically, by adjusting the PWM signals and analog input signals at the input ports of three different laser control circuits, the three different laser control output ports can output current signals with different timings and amplitudes. With each laser control output port corresponding to a laser light source of a specific color, the color of the output laser from different colors can be controlled simultaneously. For example, the three laser light sources could be red, green, and blue. Furthermore, by adjusting the PWM signals and analog input signals at the input ports of the laser control circuits corresponding to the three different laser light sources, the laser intensity, timing, and color of the three colors of laser light sources can be adjusted simultaneously and separately.

[0066] According to the control method of the laser control circuit provided in the embodiments of this disclosure, by adjusting the PWM signal and the analog input signal and inputting the PWM signal and the analog input signal into the analog switch and the first switching transistor, an enable input control signal for the current controller is obtained, so that the current controller outputs the laser control current under the control of the enable input control signal, so as to simultaneously control the brightness and timing of the laser output, thereby improving the performance of the laser control circuit.

[0067] The above description is merely a preferred embodiment of this disclosure and is not intended to limit this disclosure. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A laser control circuit, characterized in that, The laser control circuit includes: Input ports include pulse width modulation (PWM) signal input ports and analog signal input ports; An analog switch, wherein the enable input control terminal of the analog switch is connected to the PWM signal input port, and the signal input terminal of the analog switch is connected to the analog signal input port, for outputting or cutting off the analog input signal according to the PWM signal; The first switching transistor has its control terminal connected to the PWM signal input port, its current input terminal connected to the analog signal input port, and its current output terminal connected to the signal output terminal of the analog switch, and is used to control the current output of the first switching transistor according to the voltage signal of the control terminal. A current controller includes an analog frequency converter multiplexing port, which is connected to the signal output terminal of the analog switch, and is used to control the magnitude and timing of the output current according to the PWM signal and the analog input signal; The laser control output port is connected to the current output terminal of the current controller and is used to control the brightness and timing of the laser output by the laser according to the output current.

2. The laser control circuit according to claim 1, characterized in that, The current controller uses a chip with the model number MP24894.

3. The laser control circuit according to claim 1, characterized in that, The analog switch uses an RS2166 chip.

4. The laser control circuit according to claim 1, characterized in that, The first switch is an N-type metal-oxide-semiconductor (NMOS) transistor.

5. The laser control circuit according to claim 1, characterized in that, The laser control circuit further includes a buck drive circuit, which is connected between the current controller and the laser control output port. The buck drive circuit includes a first capacitor, a first inductor, a first diode, and a second switching transistor constituting a BUCK circuit. The first output terminal of the current controller is connected to the first capacitor, the second output terminal of the current controller is connected to the control terminal of the second switching transistor, and the two ends of the laser control output port are respectively connected to the two ends of the first capacitor.

6. The laser control circuit according to claim 5, characterized in that, The second switching transistor includes an NMOS transistor.

7. The laser control circuit according to claim 1, characterized in that, The laser control circuit also includes an output filter circuit, which is connected between the first output terminal of the current controller and ground, and includes a second capacitor.

8. The laser control circuit according to claim 1, characterized in that, The laser control circuit further includes an input filter circuit, which is connected between the signal output terminal of the analog switch and the analog frequency conversion multiplexing port of the current controller. The input filter circuit includes a third capacitor and a third resistor connected in parallel.

9. The laser control circuit according to claim 1, characterized in that, A set of input ports is connected to a laser control output port. The laser control circuit includes three sets of input ports and three corresponding laser control output ports, which are used to control three lasers of different colors respectively.

10. A control method applied to the laser control circuit according to any one of claims 1 to 9, characterized in that, The control method includes: By adjusting the timing of the PWM signal and the magnitude of the analog input signal, the on / off state of the analog switch and the first switching transistor is controlled, so that the current controller controls the magnitude and timing of the output current according to the PWM signal and the analog input signal, thereby controlling the brightness and timing of the laser output by the laser based on the output current.

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