JP2007324533A - Laser source driving circuit and marking device using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser source driving circuit which can eliminate a mutual variation between driving frequencies of a plurality of laser sources by a simple circuit structure, and to provide a marking device which can prevent a light receiver from operating in error without producing a phase gap of both laser light even if receiving an over-lapped portion between one laser line and another laser line by a receiver. <P>SOLUTION: The laser source driving circuit includes a plurality of frequency sources 31, 32 composed of oscillators, a plurality of laser sources which are pulse-driven at frequencies of signals produced by each frequency source, an electric source line feeding electric sources to a plurality of frequency sources, and a filter 20 which is connected to the electric source line and integrates a pulsation produced in the electric source line. The marking device includes a plurality of laser sources as sources to irradiate a horizontal line light or a vertical line light and the laser source driving circuit as a driving circuit of each laser sources. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a laser light source driving circuit for driving a plurality of pulsed laser light sources and an inking unit using the same, and in particular, to improve frequency variation and phase shift of individual laser light source driving circuits. The present invention relates to a laser light source driving circuit and a deinking device.

  There is an oscillator for a pulse laser light source that drives a laser light source with a pulse signal having a predetermined frequency. Various laser devices including a plurality of pulsed laser light sources driven by the oscillator are known. For example, a laser marking device is one of them. The laser marking device irradiates the wall surface with horizontal line light or vertical line light by the laser at the construction site or civil engineering construction site, and further irradiates the floor surface, ceiling surface, etc. with line light continuous with the vertical line light. However, it is a device for proceeding with construction and construction based on these line lights. The specification of the laser marking device may be required to be able to irradiate the line light over a wide angle range, for example, it can irradiate horizontal line light or vertical line light over the entire circumference.

A semiconductor laser is used as the light source of the ink-depositing device. This semiconductor laser, a collimator lens that makes the divergent laser light emitted from the semiconductor laser a parallel light beam, and a cylindrical lens or a cylindrical lens that diffuses the parallel light beam only in one direction And a laser light source unit. However, there is a limit to the angle at which the laser beam can be diffused by the cylindrical lens or cylindrical lens of the laser light source unit, and there is a limit to the range of line light that can be irradiated, and only with one laser light source unit, The above requirement that the line light can be irradiated over a wide angle range cannot be satisfied.
Therefore, in order to satisfy the above requirements, a plurality of laser light source units are provided so that the line light irradiated by one laser light source unit and the line light irradiated by another laser light source unit are continuous in a straight line. An inking device is provided.

  By the way, when the laser marking device is used outdoors in the daytime, it is difficult to visually confirm the laser line light irradiated on the irradiation target surface because the surroundings are bright. Even if the line light can be visually confirmed, it is difficult to accurately confirm the position. The longer the distance from the laser marking device to the irradiation target surface, the lower the brightness of the line light. Therefore, by using a light receiver, the position of the laser line light can be reliably and accurately confirmed, and the use of the laser marking device outdoors is made possible. The light receiver for the laser marking device has a light receiving element that receives the laser line light. Whether the laser line light is at the reference position of the light receiving element or not, if it is not at the reference position, in any direction from the reference position. It is comprised so that it can detect whether it has shifted | deviated. An automatic control device that sends the output of the photoreceiver to the inking unit, and controls the direction of the inking unit itself so that the line light matches the reference position of the light receiving element while observing the output of the photoreceiver on the inking unit side Has been proposed. Alternatively, the operator looks at the display on the photoreceiver, adjusts the orientation of the marking device so that the line light matches the reference position of the light receiving element, or irradiates the reference position with the line light, and the reference position of the photoreceiver Has been proposed by manual adjustment in which the light receiver is set so as to match the line light.

  The inking device described above is used so that the line light irradiated by one laser light source unit and the line light irradiated by the other laser light source unit are continuous in a straight line. When the line light is received by the light receiver, the light receiver may malfunction. That is, if there is a variation in the driving frequency of the pulse laser light source driving circuit that drives each laser light source unit, the overlapping portion of the line light from one laser light source unit and the line light from the other laser light source unit is regarded as the light receiver. When the light receiving element detects, the on / off timing of one line light and the on / off timing of the other line light continuously fluctuate, and the position of the line light received by the light receiver does not change, This is because the output of the light receiving element varies with time and the light receiver malfunctions.

In order to prevent such malfunction of the light receiver, it is necessary to stabilize the frequency of the drive circuit that drives the plurality of pulse laser light sources and to operate the individual pulse laser light sources in synchronization.
Here, a conventional example of a plurality of pulse laser light source driving circuits will be considered.
The example shown in FIG. 7 is an example in which a single frequency source 2 is provided, and this frequency source 2 is commonly used by a plurality of laser drive circuits 11, 12, 13,. Each laser light source (not shown) is pulse-driven by each laser drive circuit 11, 12, 13,.

  The example shown in FIG. 8 is an example in which frequency sources 21, 22, and 23 are provided independently corresponding to a plurality of laser drive circuits 11, 12, and 23. Power is supplied from a common power supply circuit 3 through decoupling circuits 41, 42, and 43 corresponding to. Each laser drive circuit 11, 12, 23 drives a laser light source (not shown) connected corresponding to these drive circuits, and when each laser light source is driven, a voltage is applied to the power supply line. The decoupling circuits 41, 42, and 43 are separated from each other by the power supply circuit 3 and the frequency sources 21, 22, and 23 so that the frequency drop of the frequency sources 21, 22, and 23 does not occur. Connected between.

  The example shown in FIG. 9 is an example in which a crystal resonator or a ceramic resonator is used for the oscillation circuit in order to drive the pulse laser light source at a stable frequency. The oscillation circuit has an operational amplifier 5 as a main component, a resistor 15 is connected between its input and output terminals, a capacitor 9 is connected between the input terminal and the ground, and a series circuit of a resistor 16 and a capacitor 10 is input between the output terminal and the ground. The vibrator 8 is connected between the terminal and the connection point between the resistor 16 and the capacitor 10. A signal having a constant frequency generated by the oscillation circuit is frequency-divided by the frequency dividing circuit 7 through the operational amplifier 6 and input to the laser driving circuit 1. The laser driving circuit 1 drives a laser light source (not shown) in pulse according to the input signal.

  The example shown in FIG. 10 is an example of a low-cost oscillation circuit, which is an example of a relaxation oscillator using a Schmitt trigger circuit 16. As the Schmitt trigger circuit 16, an IC can be used. A resistor 18 is connected between the input terminal and the output terminal of the Schmitt trigger circuit 16, and the input terminal is grounded via a capacitor 17. A laser light source (not shown) is driven by a constant frequency signal output from the Schmitt trigger circuit 16. In addition to the relaxation oscillator using the Schmitt trigger circuit 16, an oscillator using an operational amplifier or an LC oscillator may be used.

Each laser light source has a variation in the rising speed and the falling speed. When a plurality of laser light sources are driven by a single frequency source as shown in FIG. 7, the average output of each laser light source is It varies. Therefore, it is necessary to adjust the average output for each laser light source, and since this adjustment is complicated, there is a problem that the production cost increases.
In the example in which the frequency sources 21, 22, and 23 are individually provided corresponding to the plurality of laser driving circuits 11, 12, and 23 as in the example shown in FIG. 8, the driving frequency of each laser light source varies. Cheap. Therefore, when this is applied to, for example, a laser marking device in which the line light from one laser light source and the line light from another laser light source are overlapped and continued in a straight line, one laser line and another laser When receiving the overlapping portion with the line by the light receiver, there is a problem that the light receiver malfunctions due to the phase shift of both laser beams and the correct output of the light receiver cannot be obtained.

According to an example in which a crystal resonator or a ceramic resonator is used in the oscillation circuit as shown in FIG. 9, the crystal or ceramic resonator itself has a large size, and in addition to the purpose of driving a pulse-driven laser light source. Since the oscillation frequency is high, it is necessary to use the frequency divider 7 and there is a difficulty in miniaturization. Further, since these circuit components are required, there is a problem that the cost is increased.
The relaxation oscillator as shown in FIG. 10 has the advantage of being small and low-cost, but the oscillation frequency greatly fluctuates due to fluctuations in the power supply voltage, etc., so that a device that increases frequency accuracy with little frequency fluctuation is required. . Also, the frequency variation is large, and it is necessary to use high-precision circuit components to obtain the target frequency. In some cases, it is possible to select the target frequency from many oscillators. Sometimes required.
Other known oscillation circuits also have the disadvantage that the circuit scale is large and it is difficult to reduce the size.

  Various ideas have been made regarding the stabilization of the frequency of the laser light source, which is also described in the patent literature. One is to absorb the oscillation frequency of a semiconductor laser in a frequency-stabilized semiconductor laser that transmits the output light of the semiconductor laser through an absorption cell encapsulating a standard material and controls the oscillation frequency of the semiconductor laser to the absorption line of the standard material. Based on the outputs of the frequency control means for controlling the line, the first temperature detector for detecting the temperature of the semiconductor laser, the second temperature detector for detecting the ambient temperature, and the first and second temperature detectors. Temperature control means for controlling the temperature of the semiconductor laser (see Patent Document 1).

  In addition, a first light source for obtaining pump light and probe light for irradiating a sample can be locked to a plurality of frequencies at the same time, and in order to stabilize the frequencies of the plurality of laser light sources at a time, A second light source for obtaining light combined with the probe light of the light source, a demultiplexing means for demultiplexing light from the first light source into pump light and probe light, and a first light source Combining means for combining the probe light and the light from the second light source, and an optical path adjusting means for adjusting the pump light and the light combined by the combining means so as to oppose each other and irradiate the sample And a light detection means for detecting output light from the sample, and a frequency adjustment means for adjusting the frequency of either or both of the first light source and the second light source based on the detection value of the light detection means And a laser frequency stabilizing device is proposed. See Patent Document 2).

JP-A-7-283475 JP 2006-73755 A

The invention described in Patent Document 1 is an invention that stabilizes the oscillation frequency of a single semiconductor laser, and is not intended to eliminate a shift in driving frequency between a plurality of laser light sources, and has a difficulty in complicating the configuration. .
The invention described in Patent Document 2 is intended to stabilize the frequencies of a plurality of laser light sources at one time. However, the optical system includes a demultiplexing unit, a multiplexing unit, an optical path adjusting unit, a light detecting unit, and the like. The configuration of the optical system becomes complicated as necessary, and the frequency adjusting means adjusts the frequencies of the first light source and the second light source individually, so that the frequencies of the plurality of laser light sources are the same. It's not something to do.

The present invention solves the problems of the conventional laser light source driving circuits as shown in FIGS. 7 to 10 and eliminates variations in driving frequencies of a plurality of laser light sources while having a simple circuit configuration. An object of the present invention is to obtain a laser light source driving circuit capable of performing
The present invention also provides a laser light source driving circuit capable of eliminating variations in the driving frequencies of a plurality of laser light sources, in which line light from one laser light source and line light from another laser light source are overlapped in a straight line. By applying to the laser marking device, even if the overlapping part of one laser line and another laser line is received by the light receiver, there is no phase shift of both laser beams and the light receiver malfunctions. The aim is to obtain a sump that can be avoided.

A laser light source driving circuit according to the present invention supplies power to a plurality of frequency sources composed of oscillators, a plurality of laser light sources pulse-driven at a frequency of a signal generated by each frequency source, and a plurality of frequency sources. The main feature is that it includes a power supply line and a filter that is connected to the power supply line and integrates pulsations generated in the power supply line.
The oscillator may be an oscillator whose oscillation frequency varies depending on the power supply voltage. As such an oscillator, a relaxation oscillator or a variable voltage oscillator can be employed.
When the oscillator is a variable voltage oscillator, its control terminal is preferably connected to the power supply line.

  A laser light source driving circuit according to the present invention includes a plurality of frequency sources composed of oscillators and a plurality of laser light sources pulse-driven at the frequency of a signal generated by each frequency source, and the oscillator is an LC oscillator. There may be a configuration in which the inductor of each oscillator is magnetically coupled.

An inking device according to the present invention is an inking device that irradiates a surface to be irradiated with horizontal line light or vertical line light, and includes a plurality of laser light sources as light sources for irradiating horizontal line light or vertical line light. The laser light source driving circuit is provided as a driving circuit for each laser light source.
In the inking device, it is effective that the plurality of laser light sources are arranged so that the line lights irradiated onto the irradiation target surface by the respective laser light sources are continuously arranged in a straight line.

  When a plurality of laser light sources connected to the power supply line are driven, pulsation is generated in the power supply line. The pulsation is integrated by the filter and the pulsation is averaged to form a gentle waveform. If the phases of individual frequency sources that drive multiple laser light sources are out of phase, pulsations will occur in the power supply line at the timing when the individual laser light sources are driven, and the pulsation phase will also shift, but a filter is connected to the power supply line. As a result, the pulsation is averaged and the period becomes constant, and each frequency source outputs a signal that is drawn into the pulsation of a constant period and is synchronized in phase with each other. The light source is pulsed synchronously.

  By applying the laser light source driving circuit to an ink removal device having a plurality of laser light sources as a light source for irradiating horizontal line light or vertical line light, the plurality of laser light sources can be pulse-driven in synchronization. it can. In particular, using an inking device in which the laser light source is arranged so that the line light irradiated to the irradiation target surface by each laser light source continues in a straight line, the overlapping part of one laser line and another laser line When the light is received by the light receiver, it is possible to avoid malfunction of the light receiver because there is no phase shift between the two laser beams.

  Embodiments of a laser light source driving circuit according to the present invention and a deinking device using the same will be described below with reference to FIGS.

  In FIG. 1, a filter 20 is connected to a power supply line that supplies power to a plurality of frequency sources 31 and 32 from a power supply VCC, and power is supplied to the frequency sources 31 and 32 from a common power supply line that passes through the filter 20. The circuit configuration is as follows. The frequency sources 31 and 32 have the same circuit configuration and are relaxation oscillators mainly including Schmitt trigger circuits 161 and 162, respectively. The Schmitt trigger circuits 161 and 162 are, for example, integrated into an IC, and power is supplied to the Schmitt trigger circuits 161 and 162 from the power supply line. Resistors 181 and 182 are connected between the input and output terminals of the Schmitt trigger circuits 161 and 162, and the input terminals are connected to the ground via capacitors 171 and 172. A laser light source (not shown) is driven by output signals of the Schmitt trigger circuits 161 and 162. That is, a plurality of laser light sources that are pulse-driven at the frequency of the signal generated by each frequency source are connected to the output terminals of the Schmitt trigger circuits 161 and 162. The filter 20 is a filter that integrates pulsations generated in the power supply line. As a specific example, a circuit configuration similar to a smoothing circuit in which a coil (inductor) is connected in series to a power supply line and a capacitor is connected between both ends of the coil and the ground can be used. The filter 20 can absorb and average the voltage that rises or falls steeply.

  The frequency sources 31 and 32 in the embodiment shown in FIG. 1 are relaxation oscillators mainly composed of Schmitt trigger circuits 161 and 162, and have a characteristic that the oscillation frequency varies depending on the variation of the power supply voltage. By utilizing this characteristic, the output signals of the frequency sources 31 and 32 are synchronized by connecting the filter 20 to the power supply line. 2 and 3 illustrate the averaging of the power line pulsation and the pulling action of the frequency sources 31 and 32 according to the above embodiment.

  The frequency sources 31 and 32 are adjusted so as to output pulse signals having the same frequency, but operate independently and individually oscillate to output pulse signals. FIG. 2A shows pulse signals output from the frequency sources 31 and 32, and the first laser light source and the second laser light source are pulse-driven by these pulse signals. The characteristics of the individual frequency sources 31 and 32 have variations. Due to these variations, these output signal pulses vary in frequency. Within a limited time range, they are shown in FIG. It appears as a phase difference.

  When the first laser light source and the second laser light source are driven based on each of the above pulse signals, pulsation as shown in FIG. 2B is generated in the power supply line based on the load fluctuation. This pulsation also reflects a phase difference corresponding to the phase difference between the outputs of the frequency sources 31 and 32. However, since the first laser light source and the second laser light source are simultaneously pulse-driven, a pulsation having a waveform in which two pulsations shown in FIG. The synthesized pulsation is averaged by the filter 20, and as shown in FIG. 3, the steep rise and fall are smoothed and the period is unified. Since the oscillators constituting the frequency sources 31 and 32 are oscillators whose output signal frequency fluctuates due to fluctuations in the power supply voltage, the output signals of the frequency sources 31 and 32 according to the power supply voltage with a single pulsation cycle. The frequencies are drawn together to be unified, and the phase difference is also eliminated.

As described above, according to the above embodiment, the output frequencies of the plurality of frequency sources including the oscillators converge to the same frequency, and the phases of the laser light sources emitting pulses can be synchronized.
The laser light source driving circuit according to the above embodiment is applied to a laser marking device, and the laser light source is arranged so that the line light irradiated to the irradiation target surface by each laser light source is continuous in a straight line. When a light receiver receives an overlapping portion between a line and another laser line, a phase shift of both laser beams is eliminated, so that it is possible to avoid malfunction of the light receiver.

  FIG. 4 shows a second embodiment of the laser light source driving circuit according to the present invention. This embodiment is also configured to supply power from the power supply VCC through the filter 20 to the oscillators 51 and 52 as the respective frequency sources from a common power supply line. The filter 20 is a filter that integrates the pulsation generated in the power supply line, like the filter 20 in the above embodiment. The oscillators 51 and 52 are voltage controlled oscillators (hereinafter referred to as “VCO”), and are oscillators whose oscillation frequency changes according to the voltage applied to the control terminal. Therefore, the control terminals 511 and 521 of the oscillators 51 and 52 are connected to the power supply line via the filter 20. Laser light sources 61 and 62 are connected to output terminals of the oscillators 51 and 52, and the laser light sources 61 and 62 are pulse-driven by outputs of the oscillators 51 and 52.

  In the case of the embodiment shown in FIG. 4 as well, pulsation occurs in the power supply line when the laser light sources 61 and 62 are pulse-driven. This pulsation is integrated and averaged by the filter 20 as described above, and the pulsation period is unified, and the oscillators 51 and 52 made of VCO output the same frequency and synchronized frequency signals corresponding to the pulsation period, Based on this frequency signal, the laser light sources 61 and 62 are synchronously pulse-driven. Therefore, by applying the laser light source driving circuit shown in FIG. 4 to the laser marking device and driving the plurality of laser light sources in synchronization with each other, a marking device capable of obtaining the same effect as described above is obtained. be able to.

  The oscillator suitable for the embodiments described so far is preferably an oscillator whose oscillation frequency varies depending on the fluctuation of the power supply voltage. In addition to the oscillators shown in FIGS. A small oscillator can be used.

  FIG. 5 shows a third embodiment of the laser light source driving circuit according to the present invention. In this embodiment, the oscillators constituting the plurality of frequency sources 91 and 92 are mainly composed of transistors 71 and 72 and inductors 81 and 82, respectively. The transistors 71 and 72 constitute an LC oscillation circuit together with the inductors 81 and 82 and the two capacitors 711, 712 and 721, 722, respectively, and oscillate at a frequency determined by the inductance of these inductors and the capacitance of each capacitor. The values of the inductor and the capacitor are set so that the oscillation frequencies of the frequency sources 91 and 92 are the same. The two inductors 81 and 82 are magnetically coupled, for example, by making the cores a common common core or by arranging both cores close to each other on a straight line. Each frequency source 91, 92 is supplied with power for driving it, but in this embodiment, it is not always necessary to supply it from a common power line through a filter as in the previous embodiment. An individual power supply may be supplied.

  According to the embodiment shown in FIG. 5, since the LC oscillation circuits constituting the plurality of frequency sources 91 and 92 are magnetically coupled, the oscillation frequency of the plurality of oscillation circuits fluctuates to generate a phase difference. Then, a plurality of oscillation circuits influence each other to generate a pulling action, and the oscillation frequency of the oscillation circuit is unified and the phase is synchronized. Therefore, each laser light source can be synchronously pulse-driven by driving the laser light source for each of a plurality of frequency sources constituting the laser light source driving circuit. Further, by applying this laser light source driving circuit to a laser marking device, the same effects as in the above-described embodiment can be obtained.

  FIG. 6 shows an example in which the magnetic coupling between two LC oscillation circuits is cut off by making the directions of the inductors 81 and 82 of the LC oscillation circuit constituting the frequency sources 91 and 92 perpendicular to each other for reference. The configuration of each LC oscillation circuit is the same as the example of FIG. In the case of the circuit configuration shown in FIG. 6, since the two LC oscillation circuits are not magnetically coupled, there is no pulling-in effect between the oscillation circuits as in the example shown in FIG. The phase may be shifted.

The effects obtained by the embodiment of the present invention described above are as follows.
1. Variations in output frequency among individual frequency sources can be improved, and stable light emission performance can be obtained among a plurality of laser light sources.
2. Even if it is a low-cost and small oscillator, it is possible to obtain a laser light source driving circuit in which there is no variation in output frequency among a plurality of oscillators.
3. The greater the number of frequency sources, the more effectively the frequency variation can be improved.
4). A laser light source driving circuit board having a plurality of frequency sources can be shared, which is advantageous in reducing the cost.

It is a circuit diagram which shows one Example of the laser light source drive circuit concerning this invention. The operation of the above embodiment is shown, in which (a) is a timing chart of pulse driving of a plurality of laser light sources, and (b) is a timing chart of pulsation generated in a power supply line. It is a wave form diagram which shows the example of the pulsation of the power supply which passed the filter in the said Example. It is a circuit diagram which shows another Example of the laser light source drive circuit concerning this invention. It is a circuit diagram which shows another Example of the laser light source drive circuit concerning this invention. FIG. 6 is a circuit diagram showing an example in which the magnetic coupling of two oscillators is cut off in connection with the embodiment shown in FIG. 5. It is a circuit diagram which shows the example of the conventional laser light source drive circuit. It is a circuit diagram which shows another example of the conventional laser light source drive circuit. It is a circuit diagram which shows another example of the conventional laser light source drive circuit. It is a circuit diagram which shows another example of the conventional laser light source drive circuit.

Explanation of symbols

20 Filter 31 Frequency Source 32 Frequency Source 51 Frequency Source 52 Frequency Source 61 Laser Light Source 62 Laser Light Source 81 Inductor 82 Inductor 91 Frequency Source 92 Frequency Source 161 Schmitt Trigger Circuit 162 Schmitt Trigger Circuit

Claims (8)

A plurality of frequency sources consisting of oscillators;
A plurality of laser light sources pulsed at the frequency of the signals generated by the individual frequency sources;
A power line for supplying power to multiple frequency sources;
A laser light source driving circuit comprising: a filter that is connected to a power supply line and integrates pulsations generated in the power supply line.   2. The laser light source driving circuit according to claim 1, wherein the oscillator is an oscillator whose oscillation frequency fluctuates due to fluctuations in power supply voltage.   3. The laser light source driving circuit according to claim 2, wherein the oscillator is a relaxation oscillator.   3. The laser light source driving circuit according to claim 2, wherein the oscillator is a voltage variable oscillator.   5. The laser light source driving circuit according to claim 4, wherein a control terminal of each voltage variable oscillator is connected to a power supply line. A plurality of frequency sources consisting of oscillators;
A plurality of laser light sources pulsed at the frequency of the signals generated by the individual frequency sources,
The oscillator is an LC oscillator, and a laser light source driving circuit in which an inductor of each oscillator is magnetically coupled.   An inking device for irradiating a surface to be irradiated with horizontal line light or vertical line light, comprising a plurality of laser light sources as light sources for irradiating horizontal line light or vertical line light, and as a drive circuit for each laser light source A marking device comprising the laser light source driving circuit according to any one of claims 1 to 6. 8. The inking device according to claim 7, wherein the plurality of laser light sources are arranged so that the line lights irradiated onto the irradiation target surface by the respective laser light sources continue in a straight line.

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