JP2000022251A - Co2 laser oscillator and oscillator state detector thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit decrease in a laser intensity, avoid causing a coherent increase in laser beams, and detect an oscillation state of an oscillator, by a method wherein a means for deciding an oscillation state of the laser beams based on detection results of a current value from a power source to a CO2 oscillator is provided. SOLUTION: A laser marker is provided with a current detection circuit 23 in a laser control part 2. The current detection circuit 23 detects a current value in an electric connection of a power source 22 to a laser oscillator 3, and also a differential value between the detected current value and the previously set value is fed back to a microcomputer 21. And, the microcomputer 21 overwrites a duty ratio of a preliminary signal stored in a memory based on the differential value fed-back. Thus, even when a conductive amount to the laser oscillator 3 fluctuates, in particular increases, it is possible to adjust the duty ratio of the preliminary signal so as not to laser-oscillate by the preliminary signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to, for example CO ₂ laser oscillator that constitutes the laser marking apparatus, and CO ₂
The present invention relates to an oscillation state detection device that detects an oscillation state of a laser oscillator.

[0002]

2. Description of the Related Art A laser marking apparatus that irradiates the surface of various articles with a laser beam to mark patterns such as characters and figures can form a pattern that does not disappear. Responsibility Act) has been receiving attention with the enforcement of the Act.

[0003] Such a laser marking device, particularly using a carbon dioxide gas (CO ₂ ) as an excitation medium, comprises a laser control unit, a laser oscillator, and a scanning unit.

[0004] The laser control section comprises a microcomputer and a power supply. The microcomputer is
A print signal for marking a pattern such as a character and a figure is provided to the laser oscillator, and a scan signal for operating the scanning unit based on the pattern is provided to the scanning unit. On the other hand, the power supply has a function as a constant voltage power supply and applies a predetermined voltage to the laser oscillator.

The print signal is turned on / off by a HI / LOW signal. One pulse of the print signal corresponds to one pulse of the laser beam to be oscillated, and the laser signal is generated according to the pulse width at the HI. It is a PWM signal whose intensity can be adjusted. Since the frequency is generally fixed, the laser intensity per unit time is determined according to the duty ratio of the print signal, and the marking density is also determined according to the scanning speed (also referred to as the scanning speed) in the scanning unit. Is determined.

[0006] The laser oscillator is filled with carbon dioxide gas and has a built-in electrode. Laser oscillator
The carbon dioxide in the laser oscillator is excited based on the pulse width of the print signal given from the laser control unit, and the laser oscillates.

The scanning section has a scanner, and drives a galvano motor provided in the scanner based on a scanning signal given from the laser control section, so that a total reflection mirror provided on an output shaft of the scanner is driven. Rotate. Thereby, the laser beam oscillated from the laser oscillator is deflected and scanned, and various patterns are marked on the surface of the article to be marked.

In the laser marking apparatus as described above, it is necessary to oscillate the laser beam in a short time in accordance with the HI of the print signal in order to speed up the transfer tact of the article to be marked. In order to achieve this, the laser control unit has a duty ratio smaller than that of the print signal, and a standby signal such that the applied voltage based on the duty ratio is lower than the minimum voltage for generating laser oscillation, that is, smaller than the threshold voltage. Output. Therefore, by making the applied voltage based on the preliminary signal as close as possible to the threshold voltage, the laser beam can be oscillated in a shorter time with the print signal.

[0009] However, the threshold voltage fluctuates due to a temperature rise accompanying excitation of the laser oscillator. In particular, when the threshold voltage is lowered and the duty ratio of the spare signal is set to be relatively large, a state in which the laser beam is oscillated by the spare signal occurs. As a result, for example, when marking is performed on a place other than the article, or when the marking is not performed within the allowable range even on the surface of the article, the article becomes a defective product.

For this reason, in a conventional laser marking apparatus, a partial reflection mirror is provided in the middle of the optical path of a laser beam to deflect a part of the laser beam, and the deflected laser beam is converted by using a thermopile or a pyroelectric element. The energy generated by the laser beam is converted into an electric quantity, and the oscillation state such as ON / OFF of the laser beam or the laser intensity is detected based on the converted electric quantity, and the detection result is fed back to the laser control unit. Controlling the duty ratio of the spare signal to be smaller by a predetermined ratio,
Alternatively, measures have been taken to stop the preliminary signal so that laser oscillation is not caused by the preliminary signal.

[0011]

However, in the conventional laser marking apparatus as described above, since a part of the laser beam is deflected from a regular optical path by using a partial reflection mirror, the original laser used for marking is not used. There is a problem that the laser intensity is reduced.

On the other hand, a laser beam used for marking passes through a surface on one side of the partial reflection mirror, and a part of the laser beam is multiply reflected inside the partial reflection mirror. Through. For this reason, there is a problem that the laser beam is multiplexed by diffraction when passing through both surfaces of the partial reflection mirror, and the coherence is reduced.

In addition, in the above-described configuration, there is a problem that the need for a partially reflecting mirror and a thermopile (or a pyroelectric element or the like) leads to an increase in the entire apparatus and an increase in cost.

The present invention has been made in view of such circumstances, and focuses on the fact that power is supplied from a power supply to a laser oscillator at a constant voltage, and detects a current value from the power supply to the laser oscillator. By judging the oscillation state of the laser beam based on the result, there is no decrease in the laser intensity, no decrease in the coherence of the laser beam, and the oscillation state of the laser oscillator without increasing the overall apparatus and increasing the cost. It is an object of the present invention to provide a CO ₂ laser oscillator oscillation state detecting device capable of detecting the following, and a CO ₂ laser oscillator including the device.

[0015]

According to a first aspect of the present invention, there is provided an apparatus for detecting the oscillation state of a CO ₂ laser oscillator, wherein a predetermined voltage is applied by a power supply, and the applied voltage from the power supply is determined based on preset information. In a device that detects the oscillation state of a CO ₂ laser oscillator that oscillates a laser beam by exciting a CO ₂ gas filled therein, a detection unit that detects a current value from the power supply to the CO ₂ laser oscillator, Determining means for determining an oscillation state of the laser beam based on a detection result of the detecting means.

The oscillation state detecting apparatus of a CO ₂ laser oscillator according to the second invention, the oscillation state detecting apparatus of a CO ₂ laser oscillator of the first aspect of the invention, by adjusting the information based on a detection result of said detecting means And an adjusting means for adjusting an excited state of the CO ₂ gas.

The oscillation state detecting apparatus of a CO ₂ laser oscillator according to the third invention, in the oscillation state detecting apparatus for CO ₂ laser oscillator of the first or second invention, comparison for comparing the detection result of said detecting means with a predetermined value Means for judging the oscillation state of the laser beam based on the result of comparison by the comparing means.

In a CO ₂ laser oscillator according to a fourth aspect of the present invention, a predetermined voltage is applied by a power supply, and the applied voltage from the power supply is excited based on preset information to excite the CO ₂ gas filled therein. A CO ₂ laser oscillator that oscillates a laser beam, comprising: detecting means for detecting a current value from the power supply; and determining means for determining an oscillation state of the laser beam based on a detection result of the detecting means. Features.

The CO ₂ laser oscillator according to a fifth aspect of the invention is adjusted in CO ₂ laser oscillator of the fourth aspect of the present invention, by adjusting the information based on a detection result of said detecting means, the excited state of the CO ₂ gas It is characterized by further comprising an adjusting means for performing the adjustment.

The CO ₂ laser oscillator according to a sixth invention, in the CO ₂ laser oscillator of the fourth or fifth invention, further comprising a comparing means for comparing the detection result of said detecting means with a predetermined value, said determining means, It is characterized in that the oscillation state of the laser beam is determined based on the result of comparison by the comparing means.

[0021] comprising comprises an oscillation state detecting device and the device of the CO ₂ laser oscillator according to the first and fourth invention CO ₂
According to the laser oscillator, a predetermined voltage is applied from a power supply, and the applied voltage from the power supply is excited based on preset information to excite carbon dioxide gas (CO ₂ gas) filled in the inside of the laser. C that emits a beam
The oscillation state of the O ₂ laser oscillator, a detector for detecting the current value from the power source to the CO ₂ laser oscillator, comprising a determining means for determining oscillation state of the laser beam based on the detected result oscillation state detecting device Or a configuration in which this oscillation state detection device is provided in a CO ₂ laser oscillator.

More specifically, since the power supply from the power supply to the CO ₂ laser oscillator is a constant voltage, the state of laser oscillation such as laser intensity or ON / OFF of the laser beam is controlled by the CO ₂ laser.
It directly affects the current value when energizing the laser oscillator. Accordingly, there is no need for an optical member such as a partial reflection mirror, a thermopile, a pyroelectric element, and the like, and there is no decrease in laser intensity, decrease in coherence of a laser beam, increase in the entire apparatus, and increase in cost.

[0023] comprising comprises an oscillation state detecting device and the device of the CO ₂ laser oscillator according to the second and fifth invention CO ₂
According to the laser oscillator, the current value detected by the detecting means is fed back to adjust the aforementioned information such as information related to the preliminary signal or the print signal, thereby controlling the laser intensity or the ON / OFF of the laser beam. Since the state of the laser oscillation is adjusted, for example, by controlling the duty ratio of the spare signal to be smaller by a predetermined ratio, or by stopping the spare signal, measures are taken to prevent the laser oscillation from being caused by the spare signal. be able to.

The third and sixth comprising comprises an oscillation state detecting device and the device of the CO ₂ laser oscillator according to the invention CO ₂
According to the laser oscillator, the current value detected by the detection unit is compared with a predetermined value, and the oscillation state of the CO ₂ laser oscillator is detected based on the comparison result. For example, by using a general-purpose comparator, Thus, the oscillation state detecting device can be configured more easily.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. FIG. 1 is a block diagram illustrating an example in which a CO ₂ laser oscillator including an oscillation state detection device according to the present invention is configured as a laser marking device.

The laser marking device shown in FIG. 1 comprises an input / display 1, a laser control unit 2, a laser oscillator 3, and a scanning unit 4.

The input / display unit 1 is a touch panel type L
In addition to displaying information provided from the laser control unit 2 connected to the CD, a pattern such as a character and a graphic, and a frequency and a duty ratio of a print signal corresponding to the pattern are mainly input. The input result is provided to the laser control unit 2. Note that a configuration including a numeric key and a function key may be employed.

The laser control unit 2 includes a microcomputer 21 and a power supply 22, and stores the result of input by the input / display unit 1 in a memory (not shown) built in the microcomputer 21. Further, the laser control unit 2 supplies a print signal based on the frequency and the duty ratio stored in the memory to the laser oscillator 3 and also supplies a scan signal based on the pattern stored in the memory to the scanning unit 4. The power supply 2 has a function as a constant voltage power supply, and applies a predetermined voltage to the laser oscillator 3.

The print signal is turned on / off in accordance with the HI / LOW of the print signal, and a pulse corresponding to one pulse of the laser beam in which one pulse is oscillated.
The WM signal is a WM signal, and the laser intensity is determined based on the duty ratio according to the frequency. The laser intensity also changes depending on the scanning speed based on the frequency.

The laser oscillator 3 is filled with carbon dioxide (CO ₂ ) and has an electrode (not shown) built therein. The laser oscillator 3 is based on the duty ratio of a print signal supplied from the microcomputer 21.
Excites the carbon dioxide gas inside and causes laser oscillation.

The scanning section 4 is provided adjacent to the oscillation side of the laser oscillator 3 and includes a scanner 41. Scanning unit 4
Operates a galvano motor (not shown) included in the scanner 41 based on a scanning signal provided from the microcomputer 21 to thereby cause a total reflection mirror (not shown) provided on an output shaft of the galvano motor to operate. By rotating the laser beam, the laser beam emitted from the laser oscillator 3 is deflected and scanned to mark the surface of the workpiece W to be marked.

Further, the laser marking device according to the present invention includes a current detection circuit 23 in the laser control unit 2. In the current detection circuit 23, a resistor R is provided between the positive electrode of the power supply 22 and the positive electrode of the laser oscillator 3, and the current detection circuit 23 is connected to the resistor R in parallel. Current detection circuit 23
Detects a current value when power is supplied from the power supply 22 to the laser oscillator 3 and feeds back a difference value between the detected current value and a preset value (a reference voltage described later) to the microcomputer 21. Then, the microcomputer 21 rewrites the duty ratio of the spare signal stored in the memory based on the fed back difference value.

As a result, for example, the amount of current supplied to the laser oscillator 3 fluctuates due to a temperature rise accompanying the excitation of the carbon dioxide gas in the laser oscillator 3, and even if the amount of current increases, the laser is not oscillated by the spare signal. Thus, the duty ratio of the spare signal can be adjusted.

In the present embodiment, the duty ratio of the preliminary signal is adjusted. However, the present invention is not limited to this, and the duty ratio of the print signal may be similarly adjusted. Further, in the present embodiment, since the frequency of each signal of the preliminary signal and the print signal is fixed, in order to adjust the laser intensity, it can be achieved by adjusting the duty ratio of each signal, When considering the fluctuation of the frequency, the duty ratio is determined based on the frequency and the pulse width.

FIG. 2 is a circuit diagram showing a specific configuration example of the current detection circuit 23. 2, an electric field capacitor C18 and a fixed capacitor C19 are provided in parallel between a positive electrode (+30 V) and a negative electrode (ground) of the power supply 22. Further, the resistor R71 is an electric field capacitor C
18 and the fixed capacitor C19 are connected in parallel. Three resistors R67, R68, and R69 are connected in parallel with each other in parallel with the resistor R71, and these four resistors R67, R68, R69, and R71 are replaced with the resistor R in FIG. is there. The replacement portion with the resistor R is connected in series to the laser oscillator 3 and has a function of assisting the detection of the current detection circuit 23 connected in parallel to the replacement portion.

The current detection circuit 23 includes resistors R67 and R6.
8, R69, and R71, a terminal connected to the electrolytic capacitor C18 and the fixed capacitor C19 (capacitor side) and a terminal connected to the positive electrode of the laser oscillator 3 (oscillator side). Each is connected to two terminals.

First, the terminal on the capacitor side is grounded via resistors R76 and R78 connected in series to each other. An OP amplifier A7 is connected by its non-inverting input terminal in series with the resistor R76 and in parallel with the resistor R78. The OP amplifier A7 has a resistor R72 interposed in series between its output terminal and the inverted input terminal,
The inverting input terminal is grounded via a resistor R73 provided in parallel with the resistor R72.

On the other hand, the terminal on the oscillator side is grounded via resistors R75 and R77 and a variable resistor R55 connected in series. The same O as the OP amplifier A7 is connected in series with the resistor R75 and in parallel with the resistor R77.
P amplifier A8 is connected by its non-inverting input terminal. The operational amplifier A8 has a resistor R79 interposed in series between its output terminal and the inverting input terminal, and a resistor R74 provided in series with the output terminal of the operational amplifier A7 has one end connected to the inverting terminal of the operational amplifier A8. Connected to input terminal. An output terminal of the operational amplifier A8 is connected to an inverting input terminal of the operational amplifier A12 via a resistor R81 connected in series to the operational amplifier A8.

As described above, the eight resistors R72 to R7
9, variable resistor R55, and two OP amplifiers A7, A
The circuit constituted by 8 functions as a differential amplifier circuit that operates and amplifies voltages from terminals on the capacitor side and the oscillator side.

The OP amplifier A12 has a resistor R80 connected in parallel with each other and three fixed capacitors C36, C37, C3 between its output terminal and inverting input terminal.
38, and a non-inverting input terminal of the OP amplifier A12 is grounded via a resistor R87 connected in series thereto.

As described above, these three resistors R80,
R81, R87, three fixed capacitors C36, C3
The circuit composed of C7, C38, and OP amplifier A12 functions as an integration circuit that integrates the result of differential amplification by the above-described differential amplifier circuit.

The output terminal of the operational amplifier A12 is further connected to an inverting input terminal of an operational amplifier A13 functioning as a comparator, and the output terminal of the operational amplifier A13 is connected to the microcomputer 21.

Also, between the +15 V power supply and ground,
The resistor R66 and the Zener diode D6 are connected in series, and the Zener diode D6 is connected to the resistor R66.
Side has its cathode and the ground side has an anode.
A variable resistor R70 having one end grounded is provided in series with the resistor R66 and in parallel with the zener diode D6. A resistor R85 and a fixed capacitor C40 are connected in series between the adjustable contact of the variable resistor R70 and ground. Also, the resistor R
An electrolytic capacitor C39 is connected in series with the capacitor 85 and in parallel with the fixed capacitor C40, and one end thereof is grounded. Further, in series with the resistor R85,
The OP amplifier A1 is connected in parallel with the electrolytic capacitor C39.
3 non-inverting input terminals are connected.

As described above, these two resistors R66, R66,
R85, variable resistor R70, Zener diode D6
A circuit including the fixed capacitor C40 and the electrolytic capacitor C39 functions as a reference voltage generating circuit that applies a reference voltage to the non-inverting input terminal of the OP amplifier A13.

It is needless to say that the current detection circuit 23 is not limited to the above-described circuit configuration.

[0046]

In CO ₂ laser oscillator comprising comprises an oscillation state detecting device and the device of the CO ₂ laser oscillator according to the above described were as the present invention, together with a predetermined voltage is applied by a power supply, from the power supply The oscillation state of the CO ₂ laser oscillator that oscillates the laser beam by exciting the carbon dioxide gas (CO ₂ gas) filled therein based on the preset information on the applied voltage is indicated by C
A detecting means for detecting a current value to the O ₂ laser oscillator, and a determining means for determining an oscillating state of the laser beam based on the detected result; Is provided in the CO ₂ laser oscillator.

More specifically, since the power supply from the power supply to the CO ₂ laser oscillator is a constant voltage, the laser oscillation state such as laser intensity or ON / OFF of the laser beam is controlled by the CO ₂ laser.
It directly affects the current value when energizing the laser oscillator. Accordingly, there is no need for an optical member such as a partial reflection mirror, a thermopile, a pyroelectric element, and the like, and there is no decrease in laser intensity, decrease in coherence of a laser beam, increase in the entire apparatus, and increase in cost.

Further, by feeding back the current value detected by the detecting means and adjusting the above-mentioned information such as information relating to a preliminary signal or a print signal, the laser intensity or the ON / OFF of the laser beam can be adjusted. Since the oscillation state is adjusted, for example, control is exercised so that the duty ratio of the spare signal is reduced by a predetermined ratio, or measures are taken to prevent laser oscillation by the spare signal by stopping the spare signal. Can be.

Further, the current value detected by the detecting means is compared with a predetermined value, and the oscillation state of the CO ₂ laser oscillator is detected based on the comparison result. For example, by using a general-purpose comparator, The present invention has excellent effects, for example, the oscillation state detection device can be configured more easily.

[Brief description of the drawings]

FIG. 1 shows CO ₂ provided with an oscillation state detecting device according to the present invention.
It is a block diagram showing the example which constituted a laser oscillator as a laser marking device.

FIG. 2 is a circuit diagram showing a specific configuration example of a current detection circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Input / display 2 Laser control part 3 Laser oscillator 4 Scanning part 21 Microcomputer 22 Power supply 23 Current detection circuit

Claims (6)

[Claims] 1. A predetermined voltage is applied by a power supply, and the applied voltage from the power supply is excited based on preset information to excite a CO ₂ gas filled therein to oscillate a CO ₂ laser beam. an apparatus for detecting the oscillation state of the laser oscillator, a detector for detecting the current value from the power source to the CO ₂ laser oscillator, determining means for determining oscillation state of the laser beam based on the detection result of the detection means An oscillation state detection device for a CO ₂ laser oscillator, comprising: Wherein said by adjusting the information based on the detection result of the detecting means, the CO ₂ according to claim 1, wherein CO _2, further comprising adjusting means for adjusting the excited state of the gas
Oscillation state detection device for laser oscillator. 3. The apparatus according to claim 1, further comprising a comparing unit that compares a detection result of the detecting unit with a predetermined value, wherein the determining unit determines an oscillation state of the laser beam based on a comparison result by the comparing unit. Item 3. An apparatus for detecting an oscillation state of a CO ₂ laser oscillator according to item 1 or 2. 4. A predetermined voltage is applied by a power supply, and
The applied voltage from the source is adjusted based on preset information.
CO filled inside_TwoBy exciting the gas
CO that oscillates a laser beam_TwoIn the laser oscillator, detecting means for detecting a current value from the power supply;
Judgment of laser beam oscillation state based on detection result of stage
Characterized in that the CO _Twolaser
Oscillator. Wherein said by adjusting the information based on the detection result of the detecting means, the CO ₂ according to claim 4, wherein the CO _2, further comprising adjusting means for adjusting the excited state of the gas
Laser oscillator. 6. A comparison means for comparing a detection result of the detection means with a predetermined value, wherein the determination means determines an oscillation state of the laser beam based on a comparison result by the comparison means. Item 6. The CO ₂ laser oscillator according to item 4 or 5.