CN115356846A - A drive control device for a MEMS vibrating mirror - Google Patents

Abstract

The invention belongs to the field of MEMS galvanometers, and particularly relates to a driving control device and method of an MEMS galvanometer. The device comprises a communication interface circuit, a control circuit, a digital/analog conversion circuit, a low-pass filter circuit, a signal amplification circuit and a high-voltage generation circuit; the digital/analog conversion circuit, the low-pass filter circuit and the signal amplification circuit are sequentially connected, and the output end of the signal amplification circuit is connected with the MEMS galvanometer; the output end of the control circuit is respectively connected with the digital-to-analog conversion circuit, the low-pass filter circuit and the high-voltage generation circuit; the output end of the high-voltage generating circuit is connected with the signal amplifying circuit and the high-voltage releasing circuit; the output end of the reset circuit is respectively connected with the control circuit and the high-voltage release circuit; the communication interface circuit is connected with the control circuit. The control circuit provides the reliability thereof by configuring a reset management circuit, performing triple modular redundancy in a program and the like, can normally and stably work for a long time, and can adjust the frequency and the duty ratio of an output driving signal according to an instruction according to actual requirements.

Description

A drive control device for a MEMS vibrating mirror

technical field

The invention belongs to the field of MEMS vibrating mirrors, in particular to a drive control device for MEMS vibrating mirrors.

Background technique

MEMS galvanometers are widely used in laser beam pointing control due to their small size, low power consumption, and high control bandwidth. Especially in recent years, laser communication, precision tracking control, adaptive optics and other fields have developed rapidly, and the demand for beam pointing control technology more urgent.

The MEMS vibrating mirror is an electrostatically driven beam pointing control device. The driving control device needs to provide high voltage applied to both ends of the two axes of the MEMS vibrating mirror, and it needs to adjust the beam pointing angle applied to the two axes of the MEMS vibrating mirror according to the system requirements. Each axis is individually controlled by a differential voltage across it.

There is no sensing device in the MEMS vibrating mirror, and its control is an open-loop control, and with the increase of the shape range, the nonlinearity of its response to the voltage gradually increases. The input signal of the traditional drive control device is divided into two types: analog signal and digital signal. The analog signal input will introduce signal noise as the length of the transmission cable increases. The drive control device of the digital signal is usually through the SPI interface, which limits its control. The transmission distance of the signal, and it is necessary to provide two reference clock signals of the same source to set the cut-off frequency of the filter. If any reference clock fails, the drive control device will not work, which increases the complexity of the drive control device and reduces it. reliability. The performance of the high-voltage power supply circuit generated in the drive control device will gradually decrease with the increase of working time, which cannot meet the requirements of long-term stable work.

Contents of the invention

In order to solve the defects mentioned in the background art, the present invention presents a driving control device for a MEMS oscillating mirror.

In order to achieve the above purpose, the technical solutions are provided as follows:

A drive control device for a MEMS vibrating mirror, comprising a communication interface circuit, a control circuit, a digital/analog conversion circuit, a low-pass filter circuit, a signal amplification circuit, a high voltage generation circuit, and a high voltage release circuit;

The digital/analog conversion circuit, the low-pass filter circuit and the signal amplification circuit are connected in sequence, and the output end of the signal amplification circuit is connected to the MEMS oscillating mirror;

The output end of the control circuit is respectively connected with a digital/analog conversion circuit, a low-pass filter circuit and a high voltage generation circuit;

The output end of the high-voltage generating circuit is connected to the signal amplifier circuit and simultaneously connected to the high-voltage release circuit;

The output terminals of the reset circuit are respectively connected to the control circuit and the high voltage release circuit;

The communication interface circuit is connected with the control circuit.

Further, in the high-voltage generating circuit, the control circuit makes the control signal Vs of the power switch tube Sn output a high level, at this time the switch tube Sn is turned on, the SW is connected to the ground, the rectifier tube is reversely cut off, and the capability of the input voltage provides For an inductor, the polarity of the inductor voltage is left positive and right negative, the inductor current increases linearly, the output capacitor discharges the load, the load is a capacitive load, and the output voltage Vo drops; when Sn is turned off, the inductor current still maintains The direction of the output terminal flows, the inductor potential becomes negative on the left and positive on the right, and the rectifier is turned on. The energy stored in the inductor in the previous stage flows to C and R through the rectifier, which is equivalent to the inductor voltage and the power supply voltage. Vin is connected in series to supply power to the capacitor and the load at a voltage higher than Vin.

Further, the signal amplifying circuit is powered by dual power supplies, one is the input voltage, and the other is the high voltage generated by the high voltage generating circuit; each time the power is turned on, the low voltage power-on sequence must be prior to the high voltage power supply.

Beneficial effects of the present invention:

The present invention uses CPU or logic programmable array to realize the function of the control circuit to generate the driving signal of Sn. The control circuit provides its reliability by configuring the reset management circuit and performing triple-mode redundancy in the program, which can be normal for a long time. It works stably, and can adjust the frequency and duty cycle of the output driving signal according to the instruction according to the actual demand.

In the present invention, the communication interface circuit is used to transmit the RS422 communication protocol, and the communication protocol is analyzed through the control circuit, the digital/analog conversion circuit is controlled to generate the required analog signal, and the same source clock signal is generated through the control circuit. Thus, the interface signal is simplified, the long-distance and stable transmission of the control signal is ensured, and the reliability is improved.

The invention improves the reset circuit, in addition to discharging the high-voltage circuit when the power is just turned on, it can also realize the watchdog function for the control circuit, thereby improving the reliability of the entire drive control device.

Description of drawings

Figure 1 is a block diagram of the MEMS galvanometer drive control device;

Figure 2 is a circuit diagram of high voltage generation.

Detailed ways

In order to make the technical solution of the present invention clearer and clearer to those skilled in the art, the technical solution of the present invention will be described in detail below in conjunction with the accompanying drawings, but the embodiments of the present invention are not limited thereto.

In view of the poor reliability of the current MEMS drive control device, the short transmission of the input control signal, the lack of long-term stable work, and the non-linear response with the increase of the stroke, the present invention proposes an improved MEMS drive control device and its method. .

The high-voltage generating circuit of the traditional MEMS oscillating mirror drive control device, such as the control circuit shown in Figure 2, uses the charging and discharging of the configured capacitor of the timer to generate the on and off signals of the MOS transistor Sn, as the working time prolongs, and As the working temperature increases, the life of the capacitor will gradually degrade, which will affect the performance of the entire MEMS vibrating mirror drive control device. In order to solve this problem, the present invention proposes to use a CPU or logic programmable array to realize the function of the control circuit to generate Sn. The signal and control circuit provide its reliability by configuring the reset management circuit and performing triple-mode redundancy in the program. It can work normally and stably for a long time, and can adjust the frequency and duty of the output drive signal according to the actual demand. Compare.

The input signal of the traditional MEMS galvanometer drive control device is usually an analog signal or a digital signal of the SPI protocol, which is not conducive to the long-distance transmission of the control signal, and it is necessary to provide two homologous clock signals in the interface, and one of the clock signals fails Then the whole MEMS vibrating mirror control device cannot work normally, which increases the complexity of the interface and reduces the reliability. In the present invention, it is proposed to use the communication interface circuit to transmit communication protocols such as RS422, and analyze the communication protocol through the control circuit, control the digital/analog conversion circuit to generate the required analog signal, and generate the same source clock signal through the control circuit . Thus, the interface signal is simplified, the long-distance and stable transmission of the control signal is ensured, and the reliability is improved.

The invention improves the reset circuit, in addition to discharging the high-voltage circuit when the power is just turned on, it can also realize the watchdog function for the control circuit, thereby improving the reliability of the entire drive control device.

The MEMS vibrating mirror itself does not have a sensor feedback signal and belongs to open-loop control. With the increase of the shape, the response nonlinearity is obvious, resulting in the inability to move according to the expected position. For this reason, the present invention adds a control algorithm to the control circuit. The response characteristics of the two axes of the MEMS galvanometer are calibrated, the calibration data is stored, and the actual control straight line is fitted by the least square method, thereby improving the linearity of the two axes of the MEME galvanometer. After the control circuit analyzes the control signal transmitted from the interface circuit, it calculates the control signal actually needed by the MEMS vibrating mirror, controls the digital/analog conversion circuit to generate the control signal, and then controls the laser beam pointing more accurately.

The present embodiment is illustrated in conjunction with accompanying drawing 1, and the MEMS oscillating mirror drive control device includes a communication interface circuit, a control circuit, a digital/analog conversion circuit, a low-pass filter circuit, a signal amplification circuit, a high voltage generation circuit, and a high voltage release circuit.

This implementation mode communicates with other systems through the communication interface circuit, and communication protocols such as RS422 and RS232 can be selected as required to transmit control commands. After the control circuit receives the communication information transmitted by the communication interface circuit, it analyzes the communication protocol, uses the control algorithm to calculate the calibrated control quantity, controls the digital/analog conversion circuit to generate an analog control signal, and then filters out high-frequency interference through a low-pass filter portion.

In this embodiment, the control circuit can generate the reference clock signal for setting the cut-off frequency required in the low-pass filter circuit according to the instruction sent by the communication interface circuit, wherein the reference clocks for X1, X2 and y1, y2 are strictly synchronized.

X1, X2 and Y1, Y2 respectively act on the X-axis and Y-axis of the MEMS vibrating mirror through the differential form after passing through the signal amplification circuit. The signal amplification circuit plays the role of amplifying the voltage signal in equal proportion, and the amplification ratio can be adjusted according to the actual situation. The reference voltage of X11, X22 and Y11, Y22 is half of the voltage signal generated by the high-voltage generating circuit. The signal amplification circuit is powered by dual power supplies, one is the input voltage, and the other is the high voltage generated by the high voltage generating circuit. It is required that the low-voltage power-on sequence be prior to the high-voltage power supply every time the power is turned on.

The main function of the high-voltage generating circuit is to convert the input low-level voltage into a high-level voltage. The specific implementation method is shown in Figure 2.

In order to ensure the power-on sequence of the power supply of the signal amplifying circuit, a reset circuit and a high voltage release circuit are used in this embodiment.

The main function of the reset circuit is to generate a 200ms reset signal when the input power is first powered on, so that the control circuit remains in the reset state, and at the same time, the high voltage release circuit releases the high voltage previously stored in the energy storage capacitor of the high voltage generation circuit. Moreover, the reset circuit also has a watchdog function of the control circuit, which resets the application program in the control circuit when it cannot work normally for some reason. And it has power-down protection function.

The working process of the high-voltage generating circuit is that the control circuit makes the control signal Vs of the power switch tube Sn output a high level. At this time, the switch tube Sn is turned on, the SW is connected to the ground, the rectifier tube is reversed, and the input voltage capability is provided to the inductor. The polarity of the inductor voltage is positive on the left and negative on the right, the inductor current increases linearly, and the output capacitor discharges the load. The load is a capacitive load, the impedance to the ground is particularly large, the discharge is very slow, and the output voltage Vo drops slowly; when Sn When it is turned off, as shown in Figure 2, the inductor current still keeps flowing in the direction of the output terminal, the inductor potential becomes negative on the left and positive on the right, and makes the rectifier conduct forward, and the energy stored in the inductor in the previous stage is now rectified The tube flows to C and R. At this time, it is equivalent to that the inductor voltage is connected in series with the power supply voltage Vin, and supplies power to the capacitor and the load with a voltage higher than Vin. Each switching cycle continuously makes the voltage on the output capacitor gradually increase. In order to make the output voltage more stable and reduce the ripple, a secondary linear voltage stabilizing circuit is added in this embodiment, so that the output ripple of the high voltage generating circuit is smaller.

The above is only the best embodiment of the present invention, and is not any form of limitation to the present invention. Any person skilled in the art can use the method and content disclosed above without departing from the scope of the technical solution of the present invention. Many possible changes and modifications made to the present invention all belong to the protection scope of the claims.

Claims (3)

1. A drive control device of an MEMS galvanometer is characterized in that: the device comprises a communication interface circuit, a control circuit, a digital/analog conversion circuit, a low-pass filter circuit, a signal amplification circuit, a high-voltage generation circuit and a high-voltage release circuit;

the digital/analog conversion circuit, the low-pass filter circuit and the signal amplification circuit are sequentially connected, and the output end of the signal amplification circuit is connected with the MEMS galvanometer;

the output end of the control circuit is respectively connected with the digital-to-analog conversion circuit, the low-pass filter circuit and the high-voltage generation circuit;

the output end of the high-voltage generating circuit is connected with the signal amplifying circuit and is also connected with the high-voltage releasing circuit;

the output end of the reset circuit is respectively connected with the control circuit and the high-voltage release circuit;

the communication interface circuit is connected with the control circuit.

2. The drive control device of a MEMS galvanometer according to claim 1, characterized in that: in the high-voltage generating circuit, a control circuit enables a control signal Vs of a power switch tube Sn to output high level, the switch tube Sn is switched on at the moment, SW is connected to the ground, a rectifier tube is reversely cut off, the capacity of input voltage is provided for an inductor, the polarity of the voltage of the inductor is positive left and negative right, the current of the inductor is linearly increased, an output capacitor discharges a load, the load is a capacitive load, and the output voltage Vo is reduced; when Sn is turned off, the inductive current still keeps flowing towards the direction of the output end, the inductive potential is changed into left negative and right positive, the rectifier tube is conducted in the positive direction, the inductor flows to C and R through the rectifier tube at the last stage of energy storage, the inductive voltage is equivalent to the series connection of the inductive voltage and the power voltage Vin, and the capacitor and the load are supplied with power by the voltage higher than Vin.

3. The driving control device of the MEMS galvanometer of claim 1, wherein: the signal amplification circuit is powered by double power supplies, one is input voltage, and the other is high voltage generated by the high-voltage generation circuit; the low-voltage power-on sequence is prior to the high-voltage power supply during each power-on.

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