JP2001300747A - Device for laser beam marking - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for laser beam marking with which a speckle phenomenon of the marking is suppressed and a marking quality is improved. SOLUTION: In the device for laser beam marking, the laser beam power Pout is corrected toward a smaller side corresponding to the ratio (=L/Lmin) of the length L of a segment of a line to a normal length Lmin of a segment of a line when the length L of the segment of the line which forms a character, a figure, or the like in a marking information is shorter than the normal length Lmin of the segment of the line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser marking apparatus for marking characters, symbols, figures, etc. on the surface of an object to be marked by irradiating the object with a laser beam and scanning the object in a two-dimensional direction. .

[0002]

2. Description of the Related Art A laser marker device of this type includes a galvanomirror device having a pair of galvanomirrors to two-dimensionally change the direction of laser light. And
The control means connected to the galvanomirror device provides
When marking information on symbols, figures, and the like is input, a control signal is sent from the control means to the galvanomirror device, and both galvanomirrors are tilted in different directions by the driving means. Thereby, the laser light is turned by the two galvanometer mirrors, and the irradiation point of the laser light is scanned in a two-dimensional direction on the object to be marked.
Characters, symbols, figures, etc. are marked.

[0003] Incidentally, the driving part such as the above-mentioned galvanomirror requires a behavior delay time from the application of the control command to the start, and an acceleration time from the time of reaching the set speed. For this reason, a phenomenon occurs in which the actual irradiation point of the laser beam follows the command given from the control device to the galvanometer mirror device with a delay.

[0004] The phenomenon of the following delay will be described with reference to FIGS. 3 to 7. For example, as shown in FIG.
When the line segment is marked, the control signal includes a plurality of pieces of coordinate data P2 to P2 from the start point P1 to the end point Pn of the line segment.
The signal corresponding to Pn-1 is sequentially output to the galvanomirror device. Then, the galvanomirror device does not immediately start operating in response to the voltage corresponding to the coordinate data from the control means, and as shown in FIG. 4, a predetermined time T1 (hereinafter, this time is referred to as a “galvano behavior delay time T1”). Later). The galvano behavior delay time T1 is determined by the inertia due to the material and shape (size and weight) of the galvanometer mirror,
Further, the time is determined from the torque of the portion for driving the galvanomirror, and is constant regardless of the setting conditions such as the set printing speed Vset.

When the galvano behavior delay time T1 elapses,
The galvanomirror is started and the irradiation point of the laser beam is scanned. However, it takes a predetermined acceleration time T2 to scan at the preset print speed Vset. Then, after the acceleration time T2, the scanning speed of the laser beam reaches the set printing speed Vset, and the laser beam is scanned by a so-called constant speed operation maintained at that speed Vset.

When the laser beam irradiation point approaches the end point Pn, the galvanomirror device gradually decelerates the laser beam irradiation point so that the laser beam irradiation point can be properly stopped at the end point Pn. In short, the irradiation point of the laser beam is stopped at the end point Pn. Therefore, the galvanomirror device uses the galvano behavior delay time T1, the acceleration time T2, and the deceleration time T3 to shift the time ΔT with respect to the command from the control means.
(= T1 + T2 + T3).

When the characters, symbols, and figures to be marked are viewed in units of the respective line segments constituting them, and when these line segments are marked, if the line segments are sufficiently long, the above-mentioned behavior delay time T1 and acceleration / deceleration The times T2 and T3 are very short with respect to the time T4 (see FIG. 4) during which the constant speed operation is performed.

However, when the line segment to be marked is short, the constant speed time T4 becomes shorter and the acceleration / deceleration times T2 and T3 become longer for the following reasons. The reason is,
Since the galvanomirror device accelerates to reach the set printing speed Vset according to the deviation between the target point and the actual position, when the control means continuously outputs coordinate data from the start point to the end point of the line segment, When the line segment is long, the positional deviation from the target point becomes large, and the line is accelerated with the maximum acceleration. However, when the length of the line segment is short, the positional deviation from the target point becomes small, and the acceleration decreases. For this reason, acceleration is performed not at the maximum acceleration but at a reduced acceleration, and the acceleration time T2 until the set printing speed Vset is reached is also increased. Regarding the deceleration time T3,
The same can be said. For this reason, when the line segment to be marked is extremely short, the irradiation point of the laser beam approaches the end point of the line segment in the middle of the acceleration operation, and as shown in FIG. Therefore, the operation is performed only with the acceleration / deceleration operation without the constant velocity motion.

As described above, when the line segment to be marked is extremely short, the influence of the follow-up delay of the galvanomirror device becomes large. Therefore, the shift time ΔT (= T1 + T2 + T) from when the control means outputs the coordinate data relating to the end point to when the actual irradiation point of the laser beam reaches the end point.
3) cannot be ignored. In order to express this by a formula, the time when the control means finishes outputting the coordinate data from the start point to the end point is time Tout, and the time until the galvanomirror device reaches the irradiation point of the laser beam to the end point is marking completion time TR. If the line segment is sufficiently long, it can be expressed as Tout ≒ TR, but if the line segment is very short, TR ′ = Tout + ΔT. As shown in FIG. 6, when the line segment to be marked becomes shorter, Tout and ΔT change, but when the line segment becomes shorter than a predetermined length, the TR ′ does not change. Appears. That is, it takes a minimum required time Tmin until the marking is completed. This is a fixed time which is determined by the inertia due to the material and shape of the galvanomirror, the torque of the portion for driving the galvanomirror, and an error at the time of assembly adjustment.

[0010]

By the way, the laser marking device continues to output the laser beam until the irradiation point of the laser beam reaches the end point of the line segment. Regardless, the laser light was output from the laser light source with a constant laser power. For this reason, as described above, the laser beam is irradiated on the object to be marked with the same laser power as in the case of the long line segment, even in the case of the short line segment so that the deviation time ΔT cannot be ignored. When marking short line segments,
There has been a situation where the laser beam is excessively irradiated and the laser beam is extremely deeply carved. As a result, a so-called marking unevenness phenomenon in which line segments constituting one character / symbol / figure have different print densities for respective portions appears remarkably, resulting in a decrease in print quality.

As means for solving this problem, Japanese Patent Application Laid-Open
There are techniques disclosed in Japanese Patent Application Laid-Open Nos. 9-285882 and 07-334765. In JP-A-09-285882, the position of a galvanomirror is detected, the position deviation of the position of the galvanomirror from a target point corresponding to the coordinate data from the control means is detected, and based on the position deviation. In this configuration, feedback is performed such that the laser power is corrected one by one.

However, in this configuration, a circuit or process for detecting the position deviation of the galvanomirror with respect to the target point, and a feedback circuit or feedback in which the control means calculates and corrects the laser power based on the position deviation. The processing complicates the extra circuit configuration and processing, and increases the cost.

In Japanese Utility Model Application Laid-Open No. 07-33476, the galvanomirror is started to operate from a position before the start of drawing the marking line, and the galvanomirror is operated even when the drawing end point of the marking line is exceeded. This is a configuration in which control is performed. However, in this method, apart from the marking data of the part to be actually marked by irradiating the laser beam, the marking data before the drawing start point and the extra marking data of the extension part of the drawing end point, and this extra data This requires laser beam ON / OFF data for the marking data, which entails an increase in the memory for storing the marking data and the laser beam ON / OFF data and an increase in cost.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a laser marking apparatus capable of suppressing marking unevenness and improving printing quality.

[0015]

According to a first aspect of the present invention, there is provided a laser marking apparatus, comprising: a laser light source for emitting a laser beam; a laser beam direction; Galvano mirror device that irradiates laser light, and galvano control that outputs multiple coordinate data including the start point and end point of each line segment of marking information such as characters, symbols, and graphics to be marked on the object to be marked to the galvano mirror device Means for scanning a laser beam having a preset laser power on a target to be marked based on a preset print speed and coordinate data output from the galvano control means. In a laser marking device for marking characters, symbols, figures, etc., the galvano control means is such that the galvanomirror device is adapted to irradiate the laser beam with the laser beam. Before moving from the start point to the end point of the line segment related to the marking information, regardless of the length of the line segment, at least the required minimum required time is obtained in advance, and the line segment of the marking information is When the length is shorter than the reference line segment length obtained from the required time and the set printing speed, the correction is performed so as to lower the set laser power based on the length of the line segment.

Specifically, the galvano control means sets the minimum required time to Tmin, sets the set printing speed to Vset, sets the set laser power to Pset, and sets the length of a line segment related to the marking information to L. Then, the reference line segment length is obtained as Lmin by the formula of Lmin = Vset × Tmin, and when L <Lmin, the laser power Pout obtained by the formula of Pout = Pset × (L / Lmin) is obtained. The output of the laser light source may be controlled so that a laser beam is emitted.

[0017]

In the laser marking apparatus according to the first aspect of the present invention, if a line segment forming a character or a figure of the marking information is shorter than the reference line segment length, the line segment length depends on the line segment length. Therefore, the laser beam is corrected to reduce the set laser power, so that the laser light is not irradiated more than necessary to the object to be marked, as in the conventional case, and the situation where the object is marked deeply is prevented. The phenomenon can be suppressed and the printing quality can be improved.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.
A description will be given based on FIG. The overall configuration of the laser marker device according to the present embodiment is shown in FIG. 1, and the head unit 20 includes a laser light source 210 and a galvanometer mirror 220.
0 (corresponding to the galvanomirror device of the present invention) and the controller unit 100 (corresponding to the galvano control means of the present invention).
0A and 50B.

The galvanomirror 220 comprises a pair of galvanomirrors 220X and 220Y. One galvanomirror 220Y has its angle changed in the vertical direction by a driving means 260, and the other galvanomirror 220X moves in a horizontal direction by the driving means 260. The angle can be changed. And
The laser light emitted from the laser light source 210 is turned in two directions by the galvanomirrors 220X and 220Y, and the irradiation point of the laser light moves two-dimensionally on the workpiece W.

In the controller section 100, reference numeral 110 in FIG.
Is a console, by which characters and figures to be marked can be set, and a display unit (not shown) is provided so that input data can be confirmed.

Reference numeral 120 denotes data generating means, which comprises a pair of CPUs 1 and 2. Then, the data generating means 12
0 operates according to the flowchart shown in FIG. 2 based on the marking information input from the console 110 to generate a plurality of coordinate data. This operation will be described later in detail.

Reference numeral 140 denotes a storage means,
2 is connected to a counter 141. And storage means 1
A plurality of coordinate data generated by the data generating means 120 is stored in the memory 142 of the forty.

Numeral 130 is a control means for storing the plurality of coordinate data in the storage means 140 and sequentially taking out the coordinate data from the storage means 140 and outputting the coordinate data to the line driver / receiver 50A. Further, the control means 130 recognizes whether or not the plurality of coordinate data is coordinate data of an end point which is a start point and an end point, and outputs the plurality of coordinate data and the laser light source 2.
10 ON / OFF is controlled.

On the other hand, 230 of FIG.
Is a D / A converter, and the controller unit 10
0 to the line driver / receiver 50
A, a plurality of coordinate data sent via 50B,
Convert to the corresponding voltage.

Reference numeral 240 denotes a servo circuit which controls the driving means 260 (see FIG. 1) of the galvano mirror 220 based on the voltage from the D / A conversion means 230.

Reference numeral 250 denotes an approach state detecting means, which determines the end point based on a voltage corresponding to each coordinate data from the D / A converting means 230 and a voltage corresponding to a driving amount of the galvanometer mirror 220. The approach state of the irradiation position of the laser beam with respect to the coordinate data is detected. More specifically, the approach state detection means 250 includes a comparator 253,
It comprises a window comparator 254, an angle sensor 251 and a differentiating circuit 252. Then, the comparator 253 compares the difference between the output voltage of the D / A converter 230 and the output voltage of the angle sensor 251 with a predetermined first reference voltage, and compares the result with a first binary signal. And outputs it to the control means 130. On the other hand, the comparator 254 compares the output voltage of the differentiating circuit 252 with a predetermined second reference voltage, and outputs the result to the control unit 130 as a second binary signal.

Next, the operation of this laser marker device according to this embodiment will be described. First, marking information such as characters, symbols, and figures to be marked is input on the console 110. Since the console 110 has a display unit,
The user can input the marking information while checking the input marking information on the display unit.

Next, when a trigger signal for starting the generation of marking data is input from the console 110, the CPU 1 of the data generating means 120 receives the trigger signal and
Characters, graphics, and symbols relating to the input marking information are decomposed into line segments, and coordinate data of the start point and end point of the line segments is generated. In addition, information on a line type indicating whether the line segment is a straight line or a curve is also included in the coordinate data.

In the CPU 2 of the data generating means 120, C
Upon receiving the coordinate data from PU1, a storage start signal is output to control means 130, and control means 130 receives this signal and sets memory 142 in storage means 140 to a data writable state (write mode). .

The CPU 2 further decomposes each line segment from the start point to the end point on the basis of the information of the coordinate data from the CPU 1 to obtain coordinate data of a plurality of locus points including the start point and the end point. Is calculated, an address is assigned to each coordinate data, and the coordinate data is sequentially stored in the memory 142. The coordinate data of the locus point generated at this time also includes information on the point data indicating whether the coordinate data is the coordinate data of the start point, the coordinate data of the end point, or the coordinate data of the middle point. .

Here, the processing of the data generating means 120 will be described in detail with reference to FIG. First, in step S01 in the figure, characters, symbols, and graphics as marking information input from the console 110 are transmitted to the CPU 1 by the CPU 1.
They are decomposed into the constituent line segments, the coordinate data of the start point and the end point of each line segment are allocated, and the coordinate data is output to the CPU 2.

Then, the CPU 2 calculates the length L of the line segment (hereinafter referred to as "line length L") from the coordinate data of the start point and the end point (step S02), and sets the preset print speed Vset and the minimum The reference line length Lmin is calculated based on the required time Tmin (step S03). here,
The reference line segment length Lmin is the length of a line segment that can be printed during the minimum required time Tmin at the set printing speed Vset. The minimum required time Tmin is the minimum time during which marking cannot be performed in a shorter time than this, and this is the inertia determined from the material and shape of the galvanomirror, the torque of the driving part that drives the galvanomirror, and These are determined by adjustment errors when they are assembled.

Next, in step S04, the line segment length L is compared with the reference line segment length Lmin. If the line segment length L is smaller than the reference line segment length Lmin, the process proceeds from step S04 to YE
Proceeding to the branch of S, in step 05, the correction laser power Pout is determined based on the ratio (= L / Lmin) between the line segment L and the reference line segment length Lmin. Specifically, the laser power Pout is set to be smaller than the set laser power Pset by a change of the line segment L with respect to the reference line segment length Lmin.

On the other hand, if the line segment L is larger than the reference line segment length Lmin in step S04, the process proceeds to step S06 without correcting the set laser power Pset.

In step S06, coordinate data of the middle point, which is a plurality of locus points at predetermined intervals from the start point to the end point of the line segment, is generated (see P2 to Pn-1 in FIG. 3).

Next, in step S07, it is determined whether or not the line segment to be marked is the last line segment to be marked among the line segments constituting characters, figures, and the like. Here, with the line segment that generated a plurality of trajectory points from the start point to the end point at the present time, the coordinate data for all the line segments constituting the characters, symbols, and figures that are the input marking information has been generated. If yes, it is determined as "YES" and the preparation for marking is completed, and the "READY signal"
And wait for the input of the marking trigger. (Step S08)

On the other hand, in step S07, if the coordinate data of the trajectory point has not yet been generated for all the line segments, "NO" is determined, the process returns to step S02, and a series of processes is repeated.

As described above, the CPU 2 calculates and corrects all the coordinate data, and
2 stores all coordinate data and data of the set laser power corresponding to each line segment. And
Based on the stored data group, a galvanomirror 2
20 is driven by the servo circuit 240. At this time, a line segment L relating to a character, a figure or the like to be marked has a reference line segment length L
If it is shorter than min, correction is made to reduce the set laser power according to the length of the line segment. As a result, unlike the related art, the laser light is irradiated onto the object to be marked more than necessary, and it is possible to prevent a situation in which the object is extremely deeply carved, thereby suppressing the unevenness of the marking and improving the printing quality. . In addition, in the laser marking device of the present embodiment, since the program for operating the CPU 2 is merely changed as compared with the conventional laser marking device, it is possible to suppress an increase in cost.

The data stored in the memory 142 is supplied to the head unit 200 (galvanomirror device) as follows. That is, the control means 130 is a CPU
2 and a trigger signal for starting the marking from outside (not shown),
Output these coordinate data stored in. At this time,
The control means 130 sets the memory 142 to a state in which data can be read (read mode), and outputs a counter control signal to the counter 141 in the storage means 140. The counter 141 receives the control signal and The address 142 is sequentially counted, and the coordinate data is read and output.

The coordinate data output from the memory 142 is sent to the D / A converter 230 via the line drivers / receivers 50A and 50B, and is also sent to the controller 130.

The control means 130 determines whether the coordinate data sent from the memory 142 is the coordinate data of the starting point.
An ON / OFF signal, which is a laser control signal to be described later, is output to the laser light source 210 based on whether the data is the coordinate data of the end point, and the laser light source 210 receives the control signal and turns on / off the laser light.

The D / A converter 230 converts the sent coordinate data into a voltage and outputs the voltage to the servo circuit 240. The D / A converter 230 also includes a comparator 253 which is provided in the approach state detector 250 and serves as a first determination unit. Is also output.

The servo circuit 240 receives the voltage and drives the circuit, and controls the angle of the galvano mirror 220.
Is controlled to control the direction of the laser light from the laser light source 210, thereby scanning the laser light irradiated onto the work W in the two-dimensional direction.

An angle sensor 251 is provided in the servo circuit 240.
The angle sensor 251 detects the angle of the galvanometer mirror 220, feeds back a voltage corresponding to the angle to the servo circuit 240, and outputs the voltage to the comparator 253.

The servo circuit 240 also includes a differentiating circuit 252 as speed detecting means. The differentiating circuit 252 converts the voltage from the angle sensor 251 into a voltage corresponding to the scanning speed of the galvanometer mirror 220. , And outputs this voltage to a window comparator 254 provided in the approach state detecting means 250.

The window comparator 254 compares the voltage received from the differentiating circuit 252 with a predetermined second reference voltage, outputs the result as a second binarized signal, and outputs the second binarized signal. It is provided to the control means 130 via the line drivers 50A and 50B.

Further, another comparator 253 includes:
Voltage received from D / A conversion means 230 and angle sensor 25
1 is compared with a predetermined first reference voltage, and the result is output as a first binary signal. The first binary signal is output via the line drivers 50A and 50B. It is given to the control means 130.

When the coordinate data sent from the memory 142 is the coordinate data of the start point and the end point, the control means 130 accepts the binarized signal and outputs the angle signal with respect to the voltage from the D / A conversion means 230. The voltage difference from the sensor 251 is within a predetermined first reference voltage, and
When the voltage from the differentiating circuit 252 is within a predetermined second reference voltage, the coordinate data is sequentially transmitted. When the above requirements are not satisfied, the counter 141 counting the address of the memory 142 is repeatedly counted at the address of the coordinate data of the start point or the end point.

When sequentially sending coordinate data satisfying the above requirements, the control means 130 counts up the address of the memory 142 and sends the laser light source 210 A laser control signal (ON signal) is given to emit laser light, and when the coordinate data is the end point coordinate data, a laser control signal (OFF signal) is given to the laser light source 210 to turn off the laser light.

<Other Embodiments> The present invention is not limited to the above embodiments. For example, the following embodiments are also included in the technical scope of the present invention.
In addition to the following, various changes can be made without departing from the scope of the invention.

(1) The laser marking device according to the above-described embodiment determines, by the CPU 2, how much to correct the set laser power when the line segment of the marking information is shorter than a predetermined length.
, But is not limited to this. For example,
The correction laser power data may be created in advance by calculation, and the correction laser power data may be stored in a memory or the like. That is, any configuration may be used as long as the laser power is corrected by the time the marking is performed on the object to be marked.

(2) The laser marking apparatus according to the present embodiment is configured to correct the set laser power of a line segment having a length equal to or less than a predetermined length in accordance with the length of the line segment. The configuration may be such that one correction laser power is set for all the line segments. In this case, it is not necessary to correct the set laser power for each line segment according to the length of the line segment.
There is an effect that the processing can be simplified. Moreover, even if one correction laser power is used for all the line segments shorter than the predetermined length, the line segments shorter than the predetermined length are very short line segments. Therefore, the same effect as that of the above embodiment can be obtained.

(3) The control means 130 of the above embodiment is
Until the irradiation point of the laser beam reaches the end point which is the start point and the end point, the coordinate data of the end point was repeatedly output.However, the present invention is not limited to this. May not be output, and after confirming that the irradiation point has reached the end point, the next coordinate data may be output.

(4) In the above embodiment, the angle sensor 25
The configuration is such that it is determined whether or not the irradiation point of the laser beam has reached the end point based on both the position deviation obtained in Step 1 and the velocity deviation obtained in the differentiating circuit 252, but is not limited thereto. Instead, the configuration may be such that the determination is made based on one of the position deviation and the speed deviation.

(5) Although the data generating means 120 in the above embodiment is composed of two CPUs 1 and 2, the present invention is not limited to this, and one or three or more CPUs may be used. It may be configured.

[Brief description of the drawings]

FIG. 1 is a block diagram of a laser marking device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the laser marking device.

FIG. 3 is a conceptual diagram showing a line segment related to marking information.

FIG. 4 is a graph showing a change in a moving speed of a laser beam irradiation point.

FIG. 5 is a graph showing a change in a moving speed of a laser beam irradiation point.

FIG. 6 is a graph for explaining a minimum required time.

[Explanation of symbols]

 Reference Signs List 100 controller unit (galvano control means) 200 head unit (galvanometer mirror device) 210 laser light source 220 galvanomirror L ... line segment length Lmin ... reference line segment length P1 ... start point P2 ~ Pn ~ 1 ... coordinate data Pn ... End point Pout ... Laser power Pset ... Setting laser power Tmin ... Minimum required time Tout ... Time Vset ... Setting printing speed W ... Work (object to be marked) TR ... Marking completion time

Claims (1)

[Claims] 1. A laser light source that emits laser light, a galvano mirror device that changes the direction of the laser light and irradiates the laser light onto an object to be marked, and a character to be marked on the object to be marked. A galvano control unit that outputs a plurality of coordinate data including a start point and an end point of each line segment of marking information such as a symbol and a figure to the galvanometer mirror device, and sets a laser beam having a preset laser power preset. A laser marking device that scans the object to be marked based on the set print speed and the coordinate data output from the galvano control means to mark desired characters, symbols, figures, etc., wherein the galvano control Means, the galvanomirror device, from the start point of the line segment according to the marking information to the end point of the irradiation point of the laser beam Before moving, regardless of the length of the line segment, a minimum required minimum required time is obtained in advance, and the line segment of the marking information is obtained from the minimum required time and the set printing speed. A laser marking device for correcting the set laser power to be lower based on the length of the line segment when the length is shorter than the reference line segment length.