Pulse control method and system in laser marking process

Abstract

The invention provides a pulse control method and system for a laser marking process, and the method comprises the steps: enabling laser to emit light according to a certain light emitting frequency, and enabling the light to be turned off intermittently; in the light turn-off time period, a compensation current is applied to the laser through the pumping source, the magnitude of the compensation current is determined according to the length of the light turn-off time, and the shorter the light turn-off time is, the lower the compensation current is; the compensation current adopts a segmented compensation mode; along with the prolonging of the light turn-off time, the magnitude of the compensation current is increased in a stepped manner; and if the compensation current reaches the preset stable value and the light turn-off time is still not finished, maintaining the preset stable value by the compensation current until the light turn-off is finished. In the light-off time period of the laser, the compensation current is applied through the pumping source, so that the light-emitting pulse height of the laser tends to be consistent under the condition of any interval time, the flexibility of different light-emitting requirements of the laser is improved, and the machining precision of complex patterns is improved.

Description

Technical Field

[0001] The present invention belongs to the field of laser processing, and in particular relates to a pulse control method and system for a laser marking process. Background Art

[0002] Lasers are widely used in the processing of solar cells, power batteries, electronic devices, and other fields. Graphical processing methods place high demands on laser precision, efficiency, and compatibility, and their processing results have a significant impact on indicators such as conversion efficiency and service life. However, laser systems in related technologies still have some problems in graphic processing applications, including low processing efficiency and insufficient compatibility of the first pulse of the laser with different delay intervals. This limits the flexibility and efficiency of laser systems, making them unable to adapt to the needs of graphic processing of different sizes.

[0003] Graphics processing often requires precise and high-speed laser proofing, typically using a galvanometer scanning method. Graphics often contain multiple delayed laser intervals, which fiber lasers are unable to accommodate with complex and diverse laser off-times, resulting in significant variations in pulse height after different laser off-times. Each time a line segment wraps at the beginning or end of a graphic, the laser must be shut off to complete the galvanometer's deceleration, line wrap, and acceleration preparation phases. This lengthy line wrap preparation time significantly impacts processing efficiency. Therefore, improvements in laser processing efficiency and graphic compatibility are urgently needed.

[0004] During the laser marking process, the laser frequency is usually not adjustable. Each time the line segment changes direction and the galvanometer changes speed, the laser moves a different distance, resulting in an unstable interval between the laser light output positions, and even two light output positions overlapping. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a pulse control method and system for a laser marking process, which can make the light pulses at any interruption time highly consistent.

[0006] The technical solution adopted by the present invention to solve the above technical problems is: a pulse control method for the laser marking process, in which the laser emits light at a certain light output frequency and has intermittent light-off time; during the light-off period, a compensation current is applied to the laser through a pump source, and the magnitude of the compensation current is determined by the length of the light-off time. The shorter the light-off time, the lower the compensation current; The compensation current adopts a segmented compensation method: as the light-off time increases, the compensation current increases in a step-by-step manner; if the compensation current reaches a preset stable value and the light-off time has not ended, the compensation current maintains the preset stable value until the light-off time ends.

[0007] According to the above method, the compensation current has an initial value, and the current compensation step curve in response to the light-off time is calibrated step by step until the light-off time ends or the compensation current reaches a preset stable value.

[0008] According to the above method, the specific value of the compensation current is determined according to the test pulse height; The test pulse is obtained when no compensation current is applied during the light-off period.

[0009] According to the above method, the compensation current is increased by 0.05A each time; the time interval of each time is 200μs.

[0010] According to the above method, the preset stable value of the compensation current is less than or equal to 1.5A.

[0011] According to the above method, starting from the initial marking, the speed of the galvanometer goes through an acceleration stage, a constant stage, and a deceleration stage. In the acceleration stage and the deceleration stage, the galvanometer is variable speed marking. In the constant stage, the galvanometer is marked at a constant marking speed V. At this time, the laser emits light at a constant light frequency of 1 / T, where T is the laser constant light cycle time. During the acceleration stage and the deceleration stage, the light emission frequency of the laser is adjusted in real time so that the intervals between two adjacent light emission positions are equal.

[0012] According to the above method, in the acceleration stage or deceleration stage, the laser light emission time each time is obtained by the following formula: VT= at n 2 +V n-1 t n Where a is the acceleration of the galvanometer; t n V is the duration of this light emission; n-1 The last marking speed is determined by this formula based on the last marking conditions, where the acceleration section V0=0 and the deceleration section V0=V; According to V, a, T, V n-1 , the duration of each light emission can be obtained; as the galvanometer speed increases, the light emission frequency of the laser is adjusted to ensure that the intervals between two adjacent light marking positions are equal.

[0013] According to the above method, the laser's constant light output frequency range is 100kHz-10MHz.

[0014] According to the above method, the range of the galvanometer's constant marking speed V is 10000 mm / s-100000 mm / s, and the range of the galvanometer's acceleration a is 100000 m / s. 2 .

[0015] A laser marking system, comprising: The laser unit includes a laser light source and a pump source connected in sequence, outputting laser light for marking; A scanning unit including a galvanometer; The control unit is used to control the frequency of the laser light source, the current of the pump source and the scanning path of the galvanometer to complete the pulse control method of the laser marking process.

[0016] The beneficial effects of the present invention are: 1. During the laser off time period, a compensation current is applied through the pump source to achieve the consistency of the laser light pulse height at any interval, thereby improving the flexibility of the laser to meet different light output requirements and improving the accuracy of complex graphics processing.

[0017] 2. During the acceleration and deceleration stage of the galvanometer, the laser's light frequency is adjusted in real time to make the distance between two adjacent light-emitting positions equal, further improving the graphics processing accuracy. At the same time, it fills the waiting time for light shutoff during the variable speed marking process, greatly improving the graphics processing efficiency of the laser system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the time-current curve of the step-by-step compensation current during the light-off period.

[0019] Figure 2 This is the time-distance change curve under the galvanometer speed change. DETAILED DESCRIPTION

[0020] The present invention will be further described below with reference to specific examples and accompanying drawings.

[0021] During laser marking, the laser-processed graphics usually contain a variety of different interruption times. The present invention provides a pulse control method for the laser marking process, which can ensure that the light pulse height remains unchanged at any interruption time, that is, the pulse height of all line segments of the graphic is consistent, and the difference in light pulse height at any interruption time can be controlled within 0.1%. Specifically, during the laser marking process, the laser emits light at a certain light output frequency and has intermittent light-off time; during the light-off time period, a compensation current is applied to the laser through a pump source. The magnitude of the compensation current is determined by the length of the light-off time. The shorter the light-off time, the lower the compensation current.

[0022] This embodiment uses a segmented compensation method: as the light-off time increases, the compensation current increases in steps. If the compensation current reaches a preset stable value before the light-off time ends, the compensation current maintains the preset stable value until the light-off time ends. This method is simpler to operate and more accurate.

[0023] Furthermore, the compensation current has an initial value, and then a step-by-step current compensation curve is calibrated in response to the light-off period. The specific value of the calibrated compensation current is determined by the height of the test pulse. The test pulse is obtained using a conventional instrument, such as an oscilloscope, when no compensation current is applied during the light-off period.

[0024] The compensation current has a certain maximum value. When the light-off time increases, the pulse height compensation remains unchanged. It usually has good adaptability to the laser parameter compensation curve within a certain range. Specifically, during the light-off time, if Figure 1 As shown in the figure, the compensation current increases in a step-by-step manner as the light-off time increases. When the compensation current reaches a certain value (for example Figure 1 I in tn ), as the light-off time increases, the value of the compensation current no longer increases, that is, the subsequent compensation current remains at this value (I tn This value can be obtained by calibration and used as the preset stable value.

[0025] For each laser, after calibration, the I t1 , I t2 ···I tn The maximum compensation current value is not more than 1.5A. For different lasers, due to the different pulse heights, the I t1 , I t2 ···I tn If the light-off time is only t1+t2, then the compensation current value is only applied to I t2 If the light-off time exceeds t1+t2+…+t n , then the compensation current reaches I tn After that, the compensation current remains at I tn .

[0026] For example, the compensation current I t1 (0.7A) can effectively compensate for the height of the re-open pulse, and the compensation current I t2 (0.75A), 400μs-600μs compensation current I t3 (0.8A), each current segment sets the compensation current according to the pulse height after opening, and gradually increases with the closing time until the maximum compensation time t1+t2+…+t n (3-5ms) and then use the same compensation current I tn The pulse height is consistent.

[0027] Starting from the initial marking, the speed of the galvanometer goes through an acceleration phase, a constant phase, and a deceleration phase; during the acceleration and deceleration phases, the galvanometer performs variable speed marking; during the constant phase, the galvanometer performs marking at a constant marking speed V, at which time the laser emits light at a constant light frequency of 1 / T, where T is the laser's constant light emission cycle time. The present invention completes the galvanometer's variable speed and frequency-controlled light emission according to the graphic, that is, during the acceleration and deceleration phases, the laser's light emission frequency is adjusted in real time, so that each time the graphic line segment wraps at the beginning and end, the laser moves the same distance, and the intervals between adjacent light emission positions are equal.

[0028] During the acceleration or deceleration phase, the laser light emission duration is calculated using the following formula: VT= at n 2 +V n-1 t n Where, T is the laser constant light cycle time; a is the galvanometer acceleration; t n V is the duration of this light emission; n-1 The last marking speed is determined by this formula based on the last marking conditions, where the acceleration section V0=0 and the deceleration section V0=V; According to V, a, T, V n-1 , you can get the light emission time t n , thereby obtaining the duration of each light emission. As the galvanometer speed increases, the laser light emission frequency is adjusted to ensure that the intervals between two adjacent light emission marking positions are equal. In this embodiment, the laser constant light emission frequency range is 100kHz-10MHz, the galvanometer constant marking speed V range is 10000 mm / s-100000mm / s, and the galvanometer acceleration a range is 100000m / s 2 , thereby improving the line-changing efficiency of each line to between 1ms-100ms, and the line-changing efficiency improvement time = 2*(V / a). Obviously, the first and last marking can increase dozens to hundreds of marking light spots, greatly improving the marking efficiency.

[0029] like Figure 2 As shown, △s represents the marking interval distance. During the initial marking, the galvanometer is in the acceleration stage, and the interval between adjacent pulse intensities is large. As time goes on, the galvanometer speed gradually becomes constant, and the interval between adjacent pulse intensities gradually becomes equal. When the galvanometer speed is constant, the interval between adjacent pulse intensities remains fixed. It can be seen from the time-distance curve in the figure that at the initial stage, during the acceleration stage of the galvanometer, the marking distance increases slowly with the increase of time. When the galvanometer speed is constant, the marking distance increases faster with the increase of time. And it can be seen from the figure that after adjustment using the method of this application, the interval △s between two adjacent light-emitting positions is the same.

[0030] The present invention also provides a laser marking system, comprising a laser unit, including a laser light source and a pump source connected in sequence, outputting laser for marking; a scanning unit, including a galvanometer; and a control unit, for controlling the frequency of the laser light source, the current of the pump source, and the scanning path of the galvanometer to complete the above-mentioned laser marking process pulse control method.

[0031] In summary, the present invention increases the compensation current through the pump source of the laser during the intermittent light-off time, thereby ensuring the same pulse height at any light-emitting time, thereby improving the flexibility of the fiber laser to meet different light-emitting requirements, having higher precision in processing complex graphics, and improving the marking effect; on this basis, the galvanometer marking time, movement speed, acceleration and deceleration, and laser light-emitting frequency are set, and the laser system can be controlled to mark at equal intervals within the galvanometer acceleration and deceleration time period, filling the waiting time for light-off during the variable speed marking process, and greatly improving the graphics processing efficiency of the laser system.

[0032] In addition, this method optimizes the control of the fiber laser itself and can be expanded to more laser processing application scenarios.

[0033] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all such improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A pulse control method for a laser marking process, wherein the laser emits light at a certain frequency and has intermittent light-off time; the method is characterized by: During the light-off period, a compensation current is applied to the laser through the pump source. The magnitude of the compensation current is determined by the length of the light-off time. The shorter the light-off time, the lower the compensation current. The compensation current adopts a segmented compensation method: as the light-off time increases, the compensation current increases in a step-by-step manner; if the compensation current reaches a preset stable value and the light-off time has not ended, the compensation current maintains the preset stable value until the light-off time ends.

2. The laser marking process pulse control method according to claim 1, characterized in that: The compensation current has an initial value, and the current compensation step curve in response to the light-off time is calibrated section by section until the light-off time ends or the compensation current reaches a preset stable value.

3. The laser marking process pulse control method according to claim 2, characterized in that: The specific value of the compensation current is determined according to the test pulse height; The test pulse is obtained when no compensation current is applied during the light-off period.

4. The laser marking process pulse control method according to claim 2, characterized in that: The compensation current is increased by 0.05A each time; the time interval of each time is 200μs.

5. The laser marking process pulse control method according to claim 1 or 2, characterized in that: The preset stable value of the compensation current is less than or equal to 1.5A.

6. The pulse control method for laser marking process according to claim 1, characterized in that: From the initial marking, the speed of the galvanometer goes through an acceleration phase, a constant phase, and a deceleration phase. In the acceleration phase and the deceleration phase, the galvanometer is variable speed marking. In the constant phase, the galvanometer is marking at a constant marking speed V. At this time, the laser emits light at a constant light frequency of 1 / T, where T is the laser constant light cycle time. During the acceleration stage and the deceleration stage, the light emission frequency of the laser is adjusted in real time so that the intervals between two adjacent light emission positions are equal.

7. The laser marking process pulse control method according to claim 6, characterized in that: During the acceleration or deceleration phase, the laser light emission duration is calculated using the following formula: VT= at n 2 +V n-1 t n Where a is the acceleration of the galvanometer; t n V is the duration of this light emission; n-1 The last marking speed is determined by this formula based on the last marking conditions, where the acceleration section V0=0 and the deceleration section V0=V; According to V, a, T, V n-1 , the duration of each light emission can be obtained; as the galvanometer speed increases, the light emission frequency of the laser is adjusted to ensure that the intervals between two adjacent light marking positions are equal.

8. The laser marking process pulse control method according to claim 7, characterized in that: The laser has a constant light output frequency range of 100kHz to 10MHz.

9. The laser marking process pulse control method according to claim 7, characterized in that: The range of the constant marking speed V of the galvanometer is 10000 mm / s-100000 mm / s, and the range of the galvanometer acceleration a is 100000 m / s 2 .

10. A laser marking system, characterized in that: include: The laser unit includes a laser light source and a pump source connected in sequence, outputting laser light for marking; A scanning unit including a galvanometer; A control unit is used to control the frequency of the laser light source, the current of the pump source and the scanning path of the galvanometer to complete the laser marking process pulse control method according to any one of claims 1 to 9.

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