CN207180596U - A kind of PSD sensor signal conditionings device - Google Patents

Abstract

The utility model relates to a PSD sensor signal conditioning device, comprising a PSD sensor module, a preamplifier circuit, an analog operation circuit, an analog-to-digital conversion circuit, a data operation processing module, a display module, a serial port communication module, a PSD sensor module, and a preamplifier The circuit, the analog operation circuit, the analog-to-digital conversion circuit, and the data operation processing module are sequentially connected in series through the control circuit, and the output ports of the data operation processing module are respectively equipped with a serial communication module and a display module. The electrical signal obtained from the PSD electrode in the utility model cannot directly express the position. The PSD signal processing method of this patent is to combine the amplification circuit, the analog operation circuit, and the analog-to-digital conversion circuit to amplify the signal first, and then perform addition, subtraction and division operation processing on the electrical signal to improve the accuracy of the measurement signal, so that The relationship between the position of the light spot and the voltage value is more accurate, and then the analog position signal is converted into a digital signal, which is convenient for computer processing.

Description

A PSD sensor signal conditioning device

technical field

The utility model belongs to the technical field of signal processing and relates to sensor technology, in particular to a PSD sensor signal conditioning device.

Background technique

Position Sensitive Sensor PSD (Position Sensitive Device) is a sensor that can track the position of the light beam irradiated on its surface. Its basic structure includes a high resistance substrate and one or two layers of resistance layer covering the surface of the substrate. 1D or 2D PSD)

The sensing mechanism of PSD is very simple: if the top P layer is irradiated by a beam of light, a corresponding charge will be generated, and the size of the charge is proportional to the intensity of the light. The potential formed in the resistance layer will cause light spots and resistance on the surface of the PSD. The flow of photocurrent between the two electrodes at both ends of the layer, and the distance from the spot to the center of the PSD can be calculated after calculation based on the current. However, the electrical signal obtained from the PSD electrode cannot directly express the position, and the generated signal needs to be processed by the analog signal conditioning part and the digital signal conditioning part before it can be used. The analog part completes multi-channel signal synchronous amplification, acquisition, anti-aliasing filtering, etc. . Therefore, the analog signal conditioning circuit plays an important role in the data acquisition system.

In the PSD measurement process, the stability of the light intensity of the light source itself, the drift of the beam direction, the DC drift of the amplifier, and the dark current directly affect the measurement and positioning accuracy, especially when there are many measurement data and the measurement cycle is long, the impact is even greater. significantly.

At present, the separate PSD processing circuit has been commercialized, and there is also a single-chip application-specific integrated circuit. The circuit mainly includes preamplifier, adder, subtractor, divider and other parts, but its measurement accuracy is not high in actual measurement, and nonlinear compensation is required. However, the use of hardware circuits to realize nonlinear compensation should be affected by factors such as DC drift, and the measurement value fluctuates greatly, which affects the improvement of measurement accuracy.

Utility model content

The purpose of the utility model is to overcome the deficiencies of the prior art and provide a PSD sensor signal conditioning device with reasonable design and low cost.

The utility model solves its technical problem and realizes by taking the following technical solutions:

A PSD sensor signal conditioning device, comprising a PSD sensor module, a preamplifier circuit, an analog operation circuit, an analog-to-digital conversion circuit, a data operation processing module, a display module, a serial port communication module, a PSD sensor module, a preamplifier circuit, and an analog operation The circuit, the analog-to-digital conversion circuit, and the data operation processing module are sequentially connected in series through the control circuit, and the output ports of the data operation processing module are respectively equipped with a serial port communication module and a display module.

Moreover, it also includes a power supply module for supplying power to the computing processing module. The power supply module includes a 24V to 12V circuit and a 24V to 3.3V circuit, wherein the 24V to 12V circuit chip is a step-down switch type integrated voltage regulator chip LM2596-5, 24V The 3.3V circuit chip is AMS1117-3.3.

Also, the PSD sensor module is a segmented PSD sensor.

Moreover, the pre-amplification module is an OPA37FZ amplifier.

Moreover, the data operation processing module is an STM32 single-chip microcomputer.

Moreover, the analog operation module is a voltage-current conversion circuit.

Moreover, the digital processing module is an AD7327 chip.

Moreover, the display module is a TFT LED display module.

Advantage and positive effect of the present utility model are:

According to the operating mode of the PSD, the utility model can know that the electric signal obtained from the PSD electrode cannot directly express the position. The PSD signal processing method of this patent is to combine the amplification circuit, the analog operation circuit, and the analog-to-digital conversion circuit to amplify the signal first, and then perform addition, subtraction and division operation processing on the electrical signal to improve the accuracy of the measurement signal, so that The relationship between the position of the light spot and the voltage value is more accurate, and then the analog position signal is converted into a digital signal, which is convenient for computer processing.

Description of drawings

Fig. 1 is the circuit principle block diagram of the present utility model;

Fig. 2 is the work flowchart of the utility model;

Fig. 3 is the PSD component schematic diagram that the utility model adopts;

Fig. 4 is the PSD signal amplifying circuit diagram that the utility model adopts;

Fig. 5 is the PSD signal addition and subtraction operation circuit diagram that the utility model adopts;

Fig. 6 is the PSD signal division operation circuit diagram that the utility model adopts.

Detailed ways

The utility model will be further described in detail below in conjunction with the accompanying drawings and through specific embodiments. The following embodiments are only descriptive, not restrictive, and cannot limit the protection scope of the utility model.

A PSD sensor signal conditioning device, shown in Figure 1, includes a PSD sensor module, a preamplifier circuit, an analog operation circuit, an analog-to-digital conversion circuit, a data operation processing module, a display module, a serial port communication module, a PSD sensor module, and a preamplifier The circuit, the analog operation circuit, the analog-to-digital conversion circuit, and the data operation processing module are sequentially connected in series through the control circuit, and the output ports of the data operation processing module are respectively equipped with a serial communication module and a display module.

Its workflow is shown in Figure 2.

The power module of the single-chip microcomputer includes a 24V to 12V circuit and a 24V to 3.3V circuit. Among them, the 24V to 12V circuit chip is a step-down switch type integrated voltage regulator chip LM2596-5, and the 24V to 3.3V circuit chip is AMS1117-3.3.

The data operation and processing module is STM32 single-chip microcomputer and its minimum system circuit. The STM32 single-chip microcomputer has high-precision DA output function.

The digital processing module is the AD7327 chip. AD7327 is a high-precision analog-to-digital conversion chip with 8 channels, true bipolar input, and 12-bit resolution characteristics, and can perform operations on positive and negative voltage signals.

The display module is a TFTLED display module for displaying position information.

The working principle of the utility model is:

During position measurement, each electrode of the PSD will generate a weak current of 0-100uA. These current signals need to be converted into voltage values before the signal data can be processed. At the same time, because the current signal is too small, it is necessary to do a Zoom in and do the math. Since the output of the PSD sensor is a current signal that is not easy to handle, the front-end circuit of the PSD sensor must first be converted into a voltage signal. Because the current signal output by the PSD device is relatively weak and has a high output impedance, the performance requirements for the operational amplifier are relatively high. When selecting the type, try to choose an operation with low offset, low drift, high precision, and low bias current. amplifier, and should meet the bandwidth requirements of the modulated light source.

Through the current-voltage conversion circuit, the input current I can be converted into the input voltage V0, and there is a mathematical relationship V ₀ =-I×R _F , where R _F is the feedback resistor in the circuit. In addition, the amplification factor A _{out of} the amplifier circuit is determined by the ratio of the resistance value R _F of the feedback resistor to the resistance value R ₀ connected to the base. Through the conversion operation, the voltage value can be obtained as:

The formula shows that the output voltage V _out is proportional to the input current I, and the proportional coefficient is determined by the resistance values in the conversion circuit. Therefore, different resistance values are selected based on the appropriate current amplification factor. If the selected amplification ratio is 1:10000, then A maximum voltage of 5V can be obtained.

As shown in Figure 3, the schematic diagram of the signal generation for the PSD component.

The PSD sensor module is a segmented PSD sensor. The PSD sensor has very good stability, fast response speed and is suitable for zeroing and light centering.

The PSD elements generate current signals I-A, I-B, I-C and I-D.

The circuit for amplifying the PSD signal is shown in Figure 4. The OPA37FZ amplifier is used as the operational amplifier. This amplifier has many advantages such as small offset, sensitive response, high precision, and low noise, and can obtain more accurate measurement data. Capacitors C1, C9, C15, and C27 in the figure are used for high-frequency noise reduction.

To obtain the position coordinates of the light spot on the PSD component, it is necessary to perform mathematical operations on the output signal of the PSD. These operations are completed by the analog operation circuit. The mathematical operation part of the analog operation circuit is shown in Figures 5 and 6.

The two signals of spot coordinates (X, Y) can be expressed as:

Figure 5 is a circuit diagram of PSD signal addition and subtraction operations. The numerators in the above two formulas are added and subtracted by the two amplifiers U3 and U7 in Figure 5 respectively, and the denominators of the two formulas are the same, and the other one in Figure 5 Amplifier U12 is obtained by in-phase addition.

The division operation part of the analog operation circuit is shown in Figure 6. The signals SING3, SING2, and SING1 after the operation of the amplifiers U3, U7, and U12 are transmitted to the two dividers U4, U8.

Since the output voltage has positive and negative signals, we need to use an external high-precision A/D conversion module. AD7327 is a high-precision analog-to-digital conversion chip with 8 channels, true bipolar input, and 12-bit resolution characteristics. The serial port transmission rate is as high as 500KBPS to meet the speed and accuracy requirements of measurement.

The 4-channel output signals of A, B, C, and D need to occupy 4 channels of the A/D chip, and the chip works in single-ended mode to meet the sequential reading of the A/D sampling values of the 4 signals. The data transmission and interface control of the A/D conversion chip are realized by using the serial SPI interface, and the SPI interface of the Mega128 chip is used to control the conversion and digital signal reception of AD7327.

The single-chip microcomputer controls the A/D conversion, reads the conversion results of each channel, and selects the conversion result with ideal magnification. The PC and the single-chip microcomputer communicate in real time through the serial port, and the PC can display the measurement results and send control signals after calculating the coordinates through the host computer. Or directly use STM32 to solve the sampled data. The operation processing module uses STM32 single-chip microcomputer as the microcontroller, and the main control chip is F104RCT6. The data is stored in the buffer area of stm32, and then the X and Y values can be obtained after operation and processing. The TFTLED display module integrates a large-scale integrated circuit LCD driver inside, and adopts an 8-bit parallel method when connecting with the STM32, and the calculated coordinate values are directly displayed through the LCD.

Although the embodiments and drawings of the utility model are disclosed for the purpose of illustration, those skilled in the art can understand that various replacements, changes and modifications can be made without departing from the spirit and scope of the utility model and the appended claims. It is possible, therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims (7)

1. A kind of 1. PSD sensor signal conditionings device, it is characterised in that：Including PSD sensor assemblies, pre-amplification circuit, mould Plan computing circuit, analog to digital conversion circuit, data operation processing module, display module, serial communication modular, PSD sensor assemblies, Pre-amplification circuit, analog operational circuit, analog to digital conversion circuit, data operation processing module pass sequentially through control circuit series connection and connected Connect, the output port of data operation processing module installs serial communication modular and display module respectively.
2. 2. PSD sensor signal conditionings device according to claim 1, it is characterised in that：Also include power module, be used for Calculation process module for power supply, the power module turns 12V circuits including 24V and 24V turns 3.3V circuits, and wherein 24V turns 12V circuits Chip is step-down switching type integrated voltage-stabilized chip LM2596-5, and it is AMS1117-3.3 that 24V, which turns 3.3V circuit chips,.
3. 3. PSD sensor signal conditionings device according to claim 1, it is characterised in that：The PSD sensor assemblies are It is segmented PSD sensors.
4. 4. PSD sensor signal conditionings device according to claim 1, it is characterised in that：The pre-amplifying module is OPA37FZ amplifiers.
5. 5. PSD sensor signal conditionings device according to claim 1, it is characterised in that：The data operation handles mould Block is STM32 single-chip microcomputers.
6. 6. PSD sensor signal conditionings device according to claim 1, it is characterised in that：The simulation trial module is Voltage-current converter circuit.
7. 7. PSD sensor signal conditionings device according to claim 1, it is characterised in that：The display module is TFTLED display modules.