Focus following control method and device for laser scribing

Abstract

The invention relates to the technical field of laser precision machining, and particularly discloses a focus following control method and device for laser scribing. The method comprises the steps that processing parameters are set through upper software, and a two-way range finder is positioned; collecting material surface height data in real time, wherein analog voltage signals of the range finder and distance values are mapped according to a quantitative conversion relation; dynamically compensating the focus height deviation based on a PID algorithm; a voice coil motor is driven by a bus motion control card to adjust the position of a focus lens, and motor displacement and pulse are converted according to 10000 pulse / mm; and forward / reverse scribing respectively adopts independent range finder data to eliminate control lag errors. The device correspondingly comprises a two-way distance measuring module, a data processing module, an axis control module and a bus motion control card supporting multi-channel expansion. According to the invention, bidirectional ranging is combined with PID closed-loop control, and the line width error is controlled to be less than or equal to 20 [mu] m; 24-path synchronous focusing is supported, the focusing period is smaller than or equal to 10 ms, and the machining speed is larger than or equal to 2000 mm / s.

Description

Technical Field

[0001] The present invention relates to the field of laser precision machining technology, and specifically to a focus following control method and device for laser scribing. The method and device are particularly suitable for scenarios with high requirements for scribing accuracy, such as perovskite thin films and photovoltaic glass. The method solves the problem of inconsistent line width caused by uneven material surfaces by dynamically compensating focus errors with a bidirectional rangefinder, multi-channel synchronous focusing, and a formulated control algorithm. Background Art

[0002] In the processing of materials such as perovskite thin films and solar cells, laser scribing requires micron-level precision in line grooves (width ≤ 30μm) for separating battery cells or preparing electrodes. Due to uneven thickness (tolerance ±0.3mm) or curved surface deformation of the substrate glass, the laser focus must track surface height changes in real time. Failure to do so can lead to inconsistent line widths, edge melting, and other issues, reducing device efficiency.

[0003] Currently, the existing technology has the following technical defects: 1. Inadequate focus drift control: Traditional single-rangefinder solutions, such as the Chinese invention patent publication CN114939737A, which discloses a laser processing device, method, storage medium, and electronic device, suffer from cumulative error during bidirectional scribing due to motor response lag, resulting in line width errors ≥50μm. 2. Poor multi-channel scalability: Conventional motion control cards (such as pulse-based PCI cards) support focusing functions for a limited number of channels (usually ≤4), processing data from each channel sequentially through a time-sharing multiplexing mechanism. With this time-sharing multiplexing focusing mechanism, the focusing cycle significantly increases (>50ms) with each additional channel. This makes it impossible to support simultaneous processing of more than 24 optical paths, limiting processing efficiency (speed ≤500mm / s).

[0004] 3. The algorithm lacks quantitative control: Proportional-integral-derivative (PID) feedback control is typically used to generate focus adjustment commands. However, the general PID algorithm does not form a closed-loop mapping with hardware parameters (such as voltage-distance conversion and motor pulse equivalent), resulting in insufficient real-time response. During high-speed machining (>2000mm / s), focus tracking accuracy fluctuates by more than ±40μm, causing edge melting or wire groove breakage.

[0005] Summary of technical bottlenecks: Current laser scribing equipment faces core challenges in high-speed, multi-optical, and high-precision processing scenarios: a. Existing focus control solutions cannot simultaneously eliminate bidirectional motion errors and synchronize multiple channels in real time; b. The control algorithm is disconnected from the hardware response, making it difficult to steadily improve dynamic accuracy. Summary of the Invention

[0006] To address the three major technical issues in the background art, namely, the accumulation of bidirectional motion hysteresis errors, insufficient multi-channel real-time focusing capability, and poor control stability, the present invention provides a laser scribing focus following control method and device, aiming to achieve: 1. Eliminate focus drift in forward and reverse scribing, making the line width error ≤ 20μm; 2. Support synchronous focusing of more than 24 channels, with focusing cycle ≤10ms; 3. Ensure focus stability under high-speed processing (≥2000mm / s) through closed-loop mapping of algorithms and hardware.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions: In one aspect, the present invention provides a focus following control method for laser scribing, comprising the following steps: S1. Set the processing parameters through the upper software, and position the first and second rangefinders to the starting and end points of the processing path, respectively; S2. Start the real-time distance measurement function to collect material surface height data. The conversion relationship between the analog voltage signal output by the rangefinder and the distance value is:

[0008] in, is the reference voltage (3V), , and every 0.001V corresponds to a distance change of 1.25μm; S3. The data processing module performs real-time filtering and error compensation on the ranging data, generating focus adjustment instructions. The dynamic error compensation formula is:

[0009] in, is the current focus height deviation, are the proportional, integral, and differential coefficients; S4. The axis control module receives adjustment commands from the bus motion control card and drives the voice coil motor to move the laser focusing lens along the Z axis. The conversion relationship between motor displacement and pulse is:

[0010] Where, S=10000 pulses / mm, P is the number of pulses; S5. The first rangefinder data is used when marking in the forward direction, and the second rangefinder data is used when marking in the reverse direction, eliminating control lag errors in bidirectional motion.

[0011] Preferably, the present invention adopts an ECAT bus analog acquisition module, supports synchronous acquisition of 24 ranging channels, and the focusing instructions of each channel are synchronously executed in real time through a script programming interface, and the focusing cycle meets the following requirements:

[0012] Preferably, the response lag time of the voice coil motor satisfies:

[0013] And the bus cycle of the bus motion control card is:

[0014] To ensure focus following accuracy:

[0015] Another aspect of the present invention provides a focus following control device for laser scribing, comprising: The host computer is configured to set processing parameters and start the multi-channel distance measurement function; The two-way ranging module includes a first rangefinder and a second rangefinder installed front and back. Its analog output frequency is ≥8kHz, and the ranging data is calculated by the formula:

[0016] Convert to actual distance value; Data processing module, built-in PID control algorithm, generates adjustment instructions according to focus deviation; The axis control module is connected to the bus motion control card through the ECAT bus to drive the voice coil motor to adjust the focus lens position. The conversion relationship between motor displacement and pulse is:

[0017] The bus motion control card supports 24 analog inputs and can realize the synchronous execution of multiple focusing instructions through the script programming interface.

[0018] Preferably, the analog quantity acquisition module of the bus motion control card supports ≥48 channels through cascade expansion, and the data acquisition interval of each channel satisfies: .

[0019] Due to the adoption of the above scheme, the beneficial effects of the present invention are as follows: 1. Improved precision: The two-way ranging design combined with closed-loop control controls the line width error to ≤20μm, meeting high-precision processing requirements.

[0020] 2. Efficiency breakthrough: Multi-channel synchronous focusing supports expansion of more than 24 channels, focusing cycle ≤ 10ms, and processing speed increased to ≥ 2000mm / s.

[0021] 3. Enhanced stability: The voice coil motor works in conjunction with the high-speed bus to ensure the stability of dynamic focus tracking during high-speed processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a flow chart of the focus following control method for laser scribing according to the present invention; Figure 2 This is a structural block diagram of the focus following control device of the present invention. DETAILED DESCRIPTION

[0023] The technical solutions of the present invention will be described clearly and completely below with reference to the accompanying drawings and specific embodiments. It is obvious that the embodiments described are only a portion of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0024] Example 1: Implementation of the focus following control method for laser scribing like Figure 1 As shown, the focus following control method for laser scribing is implemented by the following steps: S1: System initialization and parameter configuration 201 Set the processing parameters through the host computer software: Processing speed: ≥2000 mm / s Target line width: ≤30 μm Material type: Perovskite thin film (substrate thickness 0.8 mm, tolerance ±0.3 mm) Position the first rangefinder (forward) and the second rangefinder (backward) to the starting point and end point of the machining path respectively, with a spacing error of ≤0.1 mm.

[0025] S2: Bidirectional ranging data acquisition and conversion 202 Start the real-time ranging function, and the rangefinder collects surface height data at a frequency of ≥8 kHz; Voltage-distance dynamic conversion: The rangefinder outputs analog voltage signal V (range: 2.76–3.24 V); According to the formula Calculate the actual distance value d (Unit: mm); Every 0.001 V corresponds to a distance change of 1.25 μm, and the zero point is automatically calibrated when the voltage drift is greater than 0.01 V.

[0026] S3: Dynamic Error Compensation and PID Control 203 The data processing module performs: Real-time filtering: Kalman filtering eliminates ± 5 μm noise; PID closed-loop feedback: Input: Focus height deviation e ( t ) = target altitude - measured altitude; Output: Adjustment instructions (The coefficients were optimized after 500 experiments); An emergency stop is triggered when the deviation is greater than 40 μm for three consecutive times.

[0027] S4: Voice coil motor drive, focus position adjustment 204 The axis control module receives instructions through the ECAT bus and drives the voice coil motor: Pulse-displacement conversion: Press Convert the pulse number PP into displacement (unit: mm); Response lag ≤ 2 ms, ensuring real-time focusing.

[0028] S5: Bidirectional motion error elimination Forward marking uses only the first rangefinder data, while reverse marking switches to the second rangefinder; When switching the motion direction, the reverse ranging data is preloaded and combined with real-time command transmission with a bus cycle of ≤1 ms to eliminate command delay and stably control the focus drift error within the range of ≤20 μm.

[0029] Technical effect: Perovskite film testing shows that the line width error is ≤18 μm and the processing speed is ≥2200 mm / s.

[0030] Example 2: Implementation structure of focus following control device like Figure 2 As shown, the focus following control device of the present invention is implemented as follows: 1. Device composition and function Host computer 101: Configure processing parameters (speed, line width) and start the multi-channel distance measurement function; Real-time monitoring of focusing accuracy (≤20 μm).

[0031] Two-way ranging module 102: The distance between the forward rangefinder 102a and the backward rangefinder 102b is adjustable (± 0.1 mm); Analog output frequency ≥ 8 kHz, data through Convert to distance value.

[0032] Data processing module 103: Built-in PID algorithm (coefficient ); Supports Kalman filtering (noise threshold ± 5 μm).

[0033] Axis control module 104: connected to bus motion control card 105 via ECAT bus; Drive the voice coil motor 106 laser focusing lens 107 Perform a displacement.

[0034] Bus motion control card 105: Support 24-channel analog input; The script programming interface enables the synchronous execution of multiple focusing commands (cycle ≤ 10 ms).

[0035] 2. Multi-channel expansion implementation Cascading ECAT bus modules expands to 48 channels; The data acquisition interval of each channel is ≤0.125 ms; Script logic example: for channel in range(48): height = read_sensor(channel)# Synchronous data collection adjust_cmd = pid_calculate(height)# PID calculation send_command(channel, adjust_cmd)#Send commands synchronously Technical effect: 48-channel synchronization error ≤ 0.8 μs, processing efficiency increased by 300%.

[0036] Technical effect verification, see Table 1 10 processing tests on perovskite films (substrate thickness 0.8 mm, fluctuation ± 0.3 mm): Table 1

Claims

1. A focus following control method for laser scribing, characterized in that: The following steps are involved: S1. Set the processing parameters through the upper software, and position the first and second rangefinders to the starting and end points of the processing path, respectively; S2. Start the real-time distance measurement function to collect material surface height data. The conversion relationship between the analog voltage signal output by the rangefinder and the distance value is: in, is the reference voltage (3V), , and every 0.001V corresponds to a distance change of 1.25μm; S3. The data processing module performs real-time filtering and error compensation on the ranging data, generating focus adjustment instructions. The dynamic error compensation formula is: in, is the current focus height deviation, are the proportional, integral, and differential coefficients; S4. The axis control module receives adjustment commands from the bus motion control card and drives the voice coil motor to move the laser focusing lens along the Z axis. The conversion relationship between motor displacement and pulse is: in, S =10000 pulses / mm, P is the number of pulses; S5. The first rangefinder data is used when marking in the forward direction, and the second rangefinder data is used when marking in the reverse direction, eliminating control lag errors in bidirectional motion.

2. The control method according to claim 1, wherein: The ECAT bus analog acquisition module supports synchronous acquisition of 24 ranging channels. The focus command of each channel is executed synchronously in real time through the script programming interface. The focus cycle meets the following requirements: 。 3. The control method according to claim 1, wherein: The response lag time of the voice coil motor satisfies: And the bus cycle of the bus motion control card is: To ensure focus following accuracy: 。 4. A focus following control device for laser scribing, characterized in that: include: The host computer is configured to set processing parameters and start the multi-channel distance measurement function; The two-way ranging module includes a first rangefinder and a second rangefinder installed front and back. Its analog output frequency is ≥8kHz, and the ranging data is calculated by the formula: Convert to actual distance value; Data processing module, built-in PID control algorithm, generates adjustment instructions according to focus deviation; The axis control module is connected to the bus motion control card through the ECAT bus to drive the voice coil motor to adjust the focus lens position. The conversion relationship between motor displacement and pulse is: The bus motion control card supports 24 analog inputs and can realize the synchronous execution of multiple focusing instructions through the script programming interface.

5. The device according to claim 4, characterized in that: The analog acquisition module of the bus motion control card supports ≥48 channels through cascade expansion, and the data acquisition interval of each channel meets the following requirements: 。

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