JP2001018078A - Laser beam marker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser beam marker capable of yielding an uniform density from a marking start point to a final point. SOLUTION: The laser beam oscillation part 1 of a laser beam marker has been miniaturized by using a rare earth-doped optical fiber for a laser beam medium of the laser beam oscillation part 1. Further, a control part 4 arranged in the laser beam marker is operated so that, while the laser beam oscillation part 1 is started and reaching a steady state, a shift quality per unit time of an irradiation position data is gradually increased according to the output rise of the laser beam oscillation part 1. Consequently, in the case of a low laser power, the scanning speed of the laser beam is reduced, an irradiation quantity of the laser beam is sufficiently secured. By this method, a uniform density from a marking start point to a final point is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser marker for marking predetermined characters and figures on an object to be marked by driving a galvanometer scanner and scanning a laser beam.

[0002]

2. Description of the Related Art A laser marker generally includes a laser oscillating unit and a galvanometer scanner. A control signal is transmitted from a control unit to the galvanometer scanner to scan a laser beam, whereby a desired marking is formed on the surface of the object to be marked. I do. A laser marker using a YAG laser as the laser oscillation section is provided. This laser oscillation unit has a total reflection mirror and a partial transmission mirror provided at both ends of a YAG crystal serving as a laser medium, and a Q switch is disposed between the partial transmission mirror and the YAG crystal.
An excitation light source is provided around the YAG crystal. Further, a control unit provided for such a laser marker controls the galvanometer scanner so as to accelerate the scanning speed of the laser beam at the starting point of the marking and then scan the laser beam at a constant speed quickly.

Incidentally, the laser marker using the YAG laser has a problem that a mirror and a Q switch are required, so that the device becomes large. As an alternative, a laser marker using an optical fiber as a laser medium is considered. Was issued. In this method, an optical fiber doped with a rare earth element is set in an excited state by energy from an excitation laser light source, and the laser light is amplified and oscillated by this energy, and does not require a Q switch.

[0004]

However, since the laser oscillation section using an optical fiber as a laser medium does not have a Q switch, the laser beam is emitted in a state where high excitation energy cannot be stored when the laser oscillation section is started. You. Therefore, the output of the laser beam by the laser oscillation unit is small at the time of startup, and the pump energy gradually accumulates and gradually increases in the optical fiber as time elapses. 3 (D)).

On the other hand, the density of the marking on the object is determined by the irradiation amount per unit length of the marking (= laser power /
(Scanning speed of laser light). Therefore, in a laser marker using an optical fiber as a laser medium, the marking becomes thin because the laser power is small until the laser oscillating unit is activated and reaches a steady state. In addition, when the control unit of the laser marker accelerates the scanning speed of the laser beam so as to become a constant speed as in the case of using the conventional YAG laser, the irradiation amount of the laser beam is further reduced, and the marking is reduced. As a result, the density of the markings near the start point and the end point becomes uneven. The present invention
The present invention has been made in view of the above circumstances, and has as its object to provide a laser marker that can have a uniform density from the start point to the end point of marking.

[0006]

According to a first aspect of the present invention, there is provided a laser marker including a laser oscillation section having an optical fiber doped with a rare earth as a laser medium, and scanning a laser beam emitted from the laser oscillation section onto an object. In a galvanometer scanner to irradiate, a control unit that controls the drive by giving a control signal consisting of irradiation position data of the laser beam to the galvanometer scanner, and a laser marker including a setting unit that can arbitrarily set a control signal in advance, the control unit includes: Until the laser oscillation unit is activated and reaches a steady state, the displacement amount of the irradiation position data per unit time is gradually increased as the output of the laser oscillation unit increases.

[0007]

According to the present invention, since a rare-earth-doped optical fiber is used as the laser medium of the laser oscillation section, it is not necessary to provide a Q switch and the like required in the conventional YAG laser. The laser oscillation section of the laser marker can be reduced in size. Since the output of such a laser oscillator gradually rises, the laser power is small near the starting point of the marking. However, the control unit provided in the laser marker according to the present invention is configured such that the displacement of the irradiation position data per unit time increases as the output of the laser oscillation unit increases until the laser oscillation unit is activated and reaches a steady state. Is gradually increased, so that the scanning speed of the laser beam can be kept low near the starting point of the marking. Therefore,
Near the starting point of the marking, the irradiation amount per unit length of the marking is sufficiently secured even if the laser power is small,
Thereby, the density can be made uniform from the start point to the end point of the marking.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION
The entire configuration is shown in FIG. 1, and the detailed configuration of the laser oscillation unit 1 is shown in FIG. First, the laser oscillation unit 1 will be described. As shown in FIG. 2, a signal semiconductor laser 10 as a signal laser light source includes a driver 1
Driven by the laser drive unit 3 via 1 to pulsate the infrared laser. Reference numeral 20 denotes a laser amplifier, which has a function of amplifying the laser light from the signal semiconductor laser 10. Here, a glass fiber (rare-earth doped optical fiber) 21 containing a rare earth element, for example, ytterbium (Yb), a first pumping semiconductor laser 22A and a second pumping semiconductor laser 22 corresponding to a pumping laser light source are provided.
B is provided. The rare earth doped optical fiber 2
1 is hatched in the drawings to distinguish it from others.

The rare-earth-doped optical fiber 21 has a required length of optical path secured by being wound around a bobbin (not shown) many times, and one of the leads wound around the bobbin is provided with laser light at the other end. Optical isolator 24 that passes only
Are provided, and two optical connectors 25A,
25B are provided. One optical connector 25A is
The laser light from the semiconductor laser 10 incident on the optical fiber 26 is incident on one end (front end) of the rare-earth doped optical fiber 21 and the laser light from the first pumping semiconductor laser 22A incident on the optical fiber 26A is converted into the rare-earth doped light. It has a function of joining the fiber 21 toward the rear end side. The other optical connector 25B is connected to the optical fiber 2
The laser beam from the second pumping semiconductor laser 22B incident on 6B has a function of being incident on the rare-earth-doped optical fiber 21 toward the front end side. Although not shown, the rare-earth-doped optical fiber 21 wound on the bobbin as described above, the optical connector 25B, the second pumping semiconductor laser 22
B and the optical fiber 26B are housed in a rectangular parallelepiped case, and are fixed by filling the case with silicone resin.

The first and second pumping semiconductor lasers 22A and 22B are controlled by the controller 4 via the laser driver 3 and the drivers 29A and 29B, respectively, and are both driven at a constant output level. The oscillation wavelength of each of the semiconductor lasers 22A and 22B is, of course, set to a wavelength suitable for exciting the rare earth element of the rare earth doped optical fiber 21.

The galvanometer scanner 2 provided in the laser marker according to the present embodiment includes a galvanometer mirror 4 for scanning the laser beam emitted from the laser oscillator 1 vertically and horizontally.
It has a well-known structure with zero. Then, the irradiation position data output from the control unit 4 to be described later and the output signal of the position sensor unit 42 are compared by a comparison unit 43, and a driving current corresponding to the comparison result is received by the mirror driving unit 41 and the galvanomirror 40 Is shifted to a position corresponding to the irradiation position data. As a result, the irradiation point of the laser beam on the object to be marked moves so as to draw predetermined characters, figures, and the like. The above-mentioned marking information such as characters and figures can be externally set by an operator by a setting unit 5 provided on the laser marker and configured by, for example, a console.

The laser marker control unit 4 provides the laser drive unit 3 with an activation signal for the laser oscillation unit 1 (see FIG. 3C), and simultaneously transmits irradiation point position data to the galvanometer scanner 2 at a constant timing. Give (Fig. 3 (B)
reference).

FIG. 3A is a graph showing the size of the irradiation point position data sequentially sent from the control unit 4, and the displacement between the irradiation point position data is represented by D1 in FIG. , D
2, D3, D4... Then, as shown in the figure, the irradiation point position data is the displacement amount of the first transmitted one (for example, D1 and D2 in FIG. 3A).
Is small, but the later this is sent, the larger the displacement gradually increases (for example, see FIG. 3).
The height difference between D2 and D3, and the height difference between D3 and D4 in (A) is compared), and the displacement is set so as to be constant (for example, D5, D6, and D6 in FIG. 3A). And compare the height difference of D7). As a result, the scanning speed of the laser beam is low at first, but is gradually increased with acceleration, and is eventually stabilized at the predetermined speed. The acceleration time is a rise time from when the laser oscillation unit 1 is activated to when the laser power reaches a steady state (see S2 in FIG. 3; for example,
(300-400 microseconds). More specifically, the irradiation point position data is obtained by: irradiation amount = (laser power) / (scanning speed of laser light) =
The laser beam is set to scan at a speed that satisfies the relationship of constant.

The present embodiment has the above configuration, and its operation will be described below. When a start switch (not shown) of the laser marker is turned on, the control unit 4 takes in the setting values and the like input by the setting unit 5 and the input data of the marking contents such as characters and graphics and the marking program. Then, the control unit 4 operates the laser driving unit 3 according to the input program and various setting values,
At the same time as supplying a start signal to the laser oscillation unit 1 (FIG.
(See FIG. 3C), and a plurality of irradiation point position data are sequentially given to the galvanometer scanner 2 (see FIG. 3B).

When the laser oscillating unit 1 receives the start-up signal, first, the excitation semiconductor laser 22A is DC-driven, and the emitted laser light enters the rare-earth doped optical fiber 21 via the optical connector 25A. As a result, the inside of the rare earth-doped optical fiber 21 is excited to generate laser light, but the laser power at this time is small. Next, the second excitation semiconductor laser 22B, which is an excitation light source, continuously oscillates at a predetermined level. Then, the second pumping semiconductor laser 22B
Is incident on the rare-earth-doped optical fiber 21 via the optical connector 25B and changes the state to a highly excited state. As a result, the laser power increases.
Then, the signal semiconductor laser 10 oscillates in pulses, and the pulsed laser light is transmitted to the optical fiber 26 and the optical connector 25.
The pulse laser light is amplified by passing through A and entering the rare-earth-doped optical fiber 21 in a highly excited state and passing therethrough. Therefore, as shown in FIG. 3D, the laser oscillation unit 1 has a behavior in which the laser power is small immediately after receiving the start signal, but this output gradually increases, and eventually the laser power settles down to a constant. Is shown.

On the other hand, the galvanometer scanner 2 is supplied with the first irradiation point position data at the same time as the start signal is transmitted to the laser oscillation section 1, and then at the fixed timing (FIG. 3B). Irradiation point position data is sequentially transmitted at each time t1, t2, t3... Then, based on these, the direction of the galvanometer mirror 40 is changed, and the irradiation point of the laser beam emitted from the laser oscillation unit 1 moves on the surface of the object to be marked, and desired characters and figures are marked. You.

By the way, as described above, the laser oscillator 1
Since the output gradually rises, the laser power is small near the starting point of the marking. However, the irradiation point position data is the irradiation amount (= laser power / laser beam scanning speed).
Is set so that the laser beam is always scanned at a constant speed. Therefore, when the laser power is small, the amount of displacement of the irradiation point position data is also small, and the scanning speed of the laser beam is suppressed to a small value. Even in the vicinity, the irradiation amount is sufficiently ensured.

When the position of the laser beam irradiation point moves away from the starting point of the marking, the laser oscillating unit 1 rises after a certain period of time has elapsed and the laser power increases. However, since the irradiation point position data is set so that the laser beam is scanned at a speed at which the irradiation amount is always constant, the displacement amount of the irradiation point position data gradually increases with an increase in the laser power, and the laser beam is scanned. Even if the light scanning speed increases and the laser power eventually increases, the irradiation amount of the laser beam per unit length of the marking does not change from the vicinity of the starting point of the marking, and therefore the density of the marking does not change. Eventually, when the laser power settles to a constant level, the displacement between the irradiation point position data also becomes constant (D5 and D in FIG. 3A).
6, D7, D8, D9), the characters and figures are marked up to the end point by the irradiation amount of the laser beam which is not different from the vicinity of the starting point of the marking.

As described above, according to the laser marker of the present embodiment, since the rare earth-doped optical fiber 21 is used as the laser medium of the laser oscillation section 1, it is not necessary to provide a Q switch or the like required for the conventional YAG laser. As a result, the laser oscillation portion of the laser marker can be downsized.
In such a laser oscillating section 1, the laser power gradually rises, but since the galvanometer scanner 2 is driven in accordance with the rising behavior, the irradiation amount of the laser beam can be made uniform from the start point to the end point of the marking. Thus, marking with uniform density can be performed from the start point to the end point.

In the laser marker of this embodiment, Q
Since the laser pulse is amplified using the rare-earth doped optical fiber 21 without using a switch, only the pulse output at the beginning of opening the Q switch generated in the Q switch system becomes abnormally large, thereby deteriorating the print quality. Absent.

<Second Embodiment> In the first embodiment,
In order to make the irradiation amount per unit length of the marking constant, the irradiation point position data is sent at a constant timing as shown in FIG. 3 (A), and the displacement amount between the irradiation point position data is made different. In this embodiment, the scanning speed of the laser beam irradiation point is gradually increased.
As shown in the figure, the displacement amount between the irradiation point position data described above is constant, and the timing of outputting the irradiation point position data is initially long, and this is gradually shortened, so that the scanning speed of the irradiation point of the laser light is reduced. Was gradually started.
Even in this case, the same operation and effect as in the first embodiment can be obtained.

<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) In the first and second embodiments, the irradiation point position data is set so that the irradiation amount per unit length of the marking is constant. However, irradiation is performed with rising laser power. The irradiation amount may not be strictly constant as long as the scanning speed of the point is increased.

(2) In each of the above embodiments, the setting unit is the console. However, the setting unit is not limited to this.

(3) In each of the above embodiments, the optical fiber is made of glass fiber, but a bendable resin optical fiber such as a plastic fiber may be used.

(4) The rare earth-doped optical fiber for amplifying and transmitting the laser beam is not limited to the one in which the rare earth element is doped over the entire length, but the part in which only the part necessary for amplification is doped with the rare earth element. Rare earth doped optical fiber can also be used.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the entire first embodiment of the present invention;

FIG. 2 is a schematic diagram showing a laser oscillation unit.

3A is a graph showing a relationship between irradiation point position data; FIG. 3B is a timing chart showing timing at which irradiation point position data is output; FIG. 3C is a timing chart of a start signal to a laser oscillation unit; Graph showing rising state of output of oscillator

FIG. 4 is a graph showing a relationship between irradiation point position data according to the second embodiment.

[Description of Signs] 1 ... Laser oscillation section 2 ... Galvanometer scanner 4 ... Control section 5 ... Setting section 21 ... Rare earth doped optical fiber

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01S 3/06 B41J 3/00 Q F term (Reference) 2C362 AA01 AA54 AA63 BA17 BA18 CB67 2H045 AB01 CB42 DA31 4E068 AB00 CA02 CA09 CA15 CB05 CB08 CC06 CE03 CK01 5F072 AB13 AB20 AK06 HH03 SS06 YY07

Claims (1)

[Claims] 1. A laser oscillation unit having an optical fiber doped with a rare earth element as a laser medium, a galvanometer scanner for scanning a laser beam emitted from the laser oscillation unit to irradiate an object, and a laser beam irradiation position data. A laser marker comprising: a control unit that supplies a control signal to the galvanometer scanner to perform drive control; and a setting unit that can arbitrarily set the control signal in advance. A laser marker which gradually increases the amount of displacement of the irradiation position data per unit time as the output of the laser oscillator increases.