JPH02220484A - Laser power-supply apparatus - Google Patents

Abstract

PURPOSE:To set and control a waveform of a driving signal to an arbitrary shape by a method wherein capacitor banks which have been charged and which supply electric power in a lamp are changed over in a preset sequence at each definite cycle. CONSTITUTION:A bank changeover means 32 used to change over, in a preset sequence at each definite cycle, capacitor banks C1 to C6 which have been charged to a desired preset voltage and which supply electric power to a lamp is installed. Accordingly, when the capacitor banks C1 to C6 are changed over at the definite cycle by using the bank changeover means 32 during a driving operation of the lamp, a driving voltage applied to a lamp 16 is changed in terms of time. A pattern (waveform) of this change is decided by a voltage of the individual capacitor banks C1 to C6, a changeover cycle and a changeover sequence. Thereby, it is possible to control the pattern to an arbitrary pattern by properly selecting a set value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a laser power supply device that supplies power to a lamp for laser excitation.

[Prior Art] Laser excitation lamps are used in optically excited solid-state lasers such as YAG lasers and glass lasers, and typical examples are Franche lamps such as xenon lamps and krypton lamps. By supplying driving power with a desired waveform to such a lamp, a laser output corresponding to the waveform can be obtained.

The applicant had previously developed a laser processing device that caused the lamp current to follow a reference waveform signal, and this
It is published as No. 0088 (Japanese Unexamined Patent Publication No. 197288/1988). According to this laser processing apparatus, by arbitrarily setting the waveform of the reference waveform signal, it is possible to obtain an arbitrary laser output waveform corresponding thereto.

In addition, in Japanese Patent Publication No. 63-20032, a high-frequency pulse train with a controllable mark-space ratio (duty ratio) is created from a DC power source, and after passing this high-frequency pulse train through a low-pass filter, it is sent as one envelope pulse to a laser excitation lamp. The power supply circuit that supplies the power is described.

According to this power supply circuit, the contour shape of the lamp drive pulse can be controlled by changing the mark-space ratio of the high-frequency pulse train during lamp drive.

[Problem to be solved by the invention] However, the above-mentioned earlier application (Japanese Patent Application No. 81-40086)
In position g, the shape and type of possible laser output waveforms are limited by the function of the reference waveform signal generation circuit.
There are times when it is not possible to set arbitrary waveforms at any time.

In addition, the above-mentioned pulse modulation type power supply circuit (Tokuko Sho-63-2
No. 0032), even if the mark-space ratio is changed, it is a small change between successive individual high-speed pulses (the mark-space ratio cannot be changed abruptly), and high-frequency ripples are more important than high-frequency pulse trains. Since the waveform of the lamp driving pulse is defined by the removed envelope, only a gentle waveform can be obtained, and a waveform that changes dynamically and arbitrarily cannot be obtained.

The present invention has been made in view of the problems of the prior art, and provides a laser electric IR device that can set and control the waveform of a drive signal for a laser excitation lamp into an arbitrary shape using a simple circuit configuration. The purpose is to provide.

Means for Solving CRM] In order to achieve the above object, the laser power supply device of the present invention includes: a plurality of capacitor banks connected in parallel to each other with respect to a laser excitation lamp; a bank charging means for charging each of the plurality of capacitor banks to a desired set voltage; The structure includes a bank switching means that can switch between banks.

Also, switching means connected between the DC power source and each of the capacitor banks so as to maintain the charging voltage of each capacitor bank at a set value; and voltage detection means for detecting the voltage of each of the capacitor banks. ; charging control means for charging each capacitor bank by controlling the switching means so that the voltage detection value from each voltage detection means matches the voltage setting value;

Also, the size of the entire capacitor bank and hence the arI
In order to make the size compact, a configuration was adopted in which a capacitor bank had a capacitance corresponding to each set voltage.

[Operation] When the capacitor bank is switched at regular intervals by the bank switching means while the lamp is being driven, the drive voltage applied to the lamp changes over time.

The pattern (waveform) of this change is determined by the voltage of each capacitor bank, the switching period, and the switching sequence, so any pattern can be obtained by appropriately selecting the set values.

In addition, by monitoring the voltage of each capacitor bank and when it drops below the set value, the switching means is immediately turned on to charge the voltage and return it to the set value, thereby stabilizing the voltage of each bank even when the lamp is running. can be maintained.

Furthermore, a capacitor with a small capacity and therefore a small size can be selected for a bank with a relatively low set voltage, and in this case, the size of the entire bank and, therefore, the size of the device can be made compact.

Embodiment FIG. 1 shows a circuit configuration of a laser power supply device according to an embodiment of the present invention.

In FIG. 1, for the lamp 14 for laser excitation,
6 capacitor banks (hereinafter simply referred to as banks)
C1 to C6 are connected in parallel to each other. Each bank C
A switching transistor Tri for bank switching, a protection diode dll, and a common coil 14 are connected between the bank switching transistor Tri, a protection diode dll, and a common coil 14. Also,
Between each bank C1 and the DC voltage input terminal to, 12, a charging field effect transistor (FET) Fi,
A-flow diode d1. Coil Li is connected.

A diode D1. is connected between each adjacent bank CI, Ci÷1. I+1 is connected. Shimmer circuit 18
is the lamp 1 during pulse lighting (pulsed laser oscillation).
This is to maintain the discharge path in 6 in a standby state, and 100
A weak preliminary current of about 200 mA is supplied to the lamp 16. Note that a circuit (not shown) for starting the lamp 16 is also provided.

The bank charging circuit of this embodiment is as follows.

Setting values Vl-V2 for the respective voltages of banks CI-Chi are input from a keyboard (not shown) to the voltage setting circuit 22 via the external interface 20.

The setting circuit 22 provides these set values Vl-VG to the comparison circuit 24. On the other hand, the voltage detection circuit 28
Detect the actual voltages of each of the CGs and calculate their detected values V! ~v6 is given to the comparison circuit 24. The comparison circuit 24 is
The set value v1 and the detected value v1 are compared for each bank CI, and if there is a comparison error, the corresponding FET (Fl) is turned on via the gate drive circuit 26 so as to reduce it to zero. As a result, the power supply voltage EO becomes
and is supplied to the bank CI via the coil Ll, and when the detected value V[ matches the set value V1, the comparison circuit 24 outputs the FE
T(Fl) is turned off, and charging is now completed. In this way, when setting the bank voltage and during lamp driving as described later, the voltage v1 of each bank CI is set to the set value VI.
If the bank CI is insufficient, the bank CI is immediately charged, thereby maintaining each bank voltage vl at the set value.

The set voltage of banks CI-CG can be arbitrarily selected, and may have different values with a constant step width as shown below, for example.

Vl (CI) 300V V2 (C2) 350V V3 (C3) 400V V4 (C4) 450V V5 (C5) 500V VG (CG) 550V Note that the capacitance of banks CI-Chi is selected to correspond to each set voltage. It's fine. In this case, the bank Cl-C5 with a relatively low set voltage may have a small capacity and a small size, and the installation space of the entire bank becomes small.

Next, a circuit for driving the lamp 16 by switching banks CI-CG will be described.

First, prior to driving the lamp, a bank switching sequence is set. FIG. 2 shows an example of a bank switching sequence. In this example, starting from CI, C5, C
B, C3... and so on. Such sequence data can be accessed from the external interface 2 using a keyboard, etc.
0 and is stored in the discharge order setting circuit 34. Further, the switching period ΔT is also set to an arbitrary value, and the set value is stored in the switching period setting circuit 36.

Then, when the start circuit 40 is activated and lamp driving is started, the bank switching circuit 32 performs bank switching control according to the above-mentioned setting. That is, the switching circuit 32
sequentially reads sequence data from the setting circuit 34 in response to a clock signal CK having a set period ΔT from the timing circuit 38, and drives the transistor Trl- by the control signal Bl-BG via the base drive circuit 30.
Switch TrG on/off.

FIG. 3 shows the on/off operation of the transistor Trl"TrG corresponding to the bank switching sequence of FIG. 2. During the first unit pulse period ΔT, the transistor Tr"
l is turned on, which causes the voltage vl of bank CI to
(300V) is applied to the lamp 16 via the diode dll and the coil 14. Next unit pulse period Δ
At T, transistor Tr5 is turned on and bank C5
A voltage v5 (500V) is applied to the lamp 16 via the diode d15 and the coil 14. In this way, according to the sequence data (FIG. 2) set and input to the discharge order setting circuit 34, the bank CI to which power is to be supplied to the lamp 16 is switched at every fixed period ΔT. As a result, a drive voltage having a pulse waveform as shown in FIG. 4 is supplied to the lamp 16, and a laser output having a waveform (actually, a curved waveform with rounded corners) corresponding to the waveform shown in the figure is obtained. .

Note that when the voltage of the bank CI drops during lamp drive, the bank C1 is immediately charged by the function of the charging circuit as described above. Further, when the power decreases so rapidly and significantly that the charging circuit cannot catch up, charging is performed from the adjacent bank Cif through the diode DI-1,i.

The drive voltage waveform shown in FIG. 4 is an example, and any waveform can be obtained by appropriately selecting and setting the bank setting voltage, bank switching sequence, and unit pulse width (switching cycle).

It is also possible to use a FET or thyristor switching element in place of the bank switching transistor Trl-T2.
Similarly, F6) can be replaced with another switching element.

Further, the voltage setting circuit 22. Comparison circuit 24. Bank switching circuit 32. Discharge order setting circuit 34. Switching cycle setting circuit 36
etc., can also be configured by a microcomputer.

Furthermore, it is possible to select any number of banks,
If the number is increased, the step width between bank voltages can be reduced or the dynamic range can be expanded, allowing more precise waveform control with a greater degree of freedom.

[Effects of the Invention] The present invention achieves the following effects by implementing the above-described configuration.

Multiple capacitor banks are provided for the laser excitation lamp, and when driving the lamp, the banks are switched at regular intervals according to the set sequence, so the bank voltage and switching cycle.

By appropriately selecting the bank discharge (switching) order, any desired lamp drive waveform can be obtained.

In addition, when the voltage of each capacitor bank O falls below the set value, the switching means is immediately turned on to charge the voltage and return it to the set value, thereby making it possible to maintain the voltage of each bank at the set value even while the lamp is running. .

Furthermore, by setting the bank capacity according to the set voltage of each bank, for example, the size of the bank with a low set voltage can be made small, and the size of the entire bank, and thus the size of the entire device, can be made compact.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the circuit configuration of a laser power supply device according to an embodiment of the present invention, FIG. 2 is a diagram showing an example of setting a bank switching sequence according to the embodiment, and FIG. 3 is a control of bank switching. A signal timing diagram for explaining the operation and FIG. 4 are signal waveform diagrams showing lamp drive voltage waveforms obtained in a setting example of the embodiment. C1~CG...Capacitor bank, F1~F6...
...FET. Trl"TrG...transistor, 16...lump for laser excitation, 22...voltage setting circuit, 24...comparison circuit, 28...voltage detection circuit, 32... Bank switching circuit, 34...discharge order setting circuit, 36...switching cycle setting circuit, 38...timing circuit.

Claims (3)

[Claims] (1) A laser power supply device that drives a lamp for laser excitation, including a plurality of capacitor banks connected in parallel to the lamp, and a bank charger that charges each of the capacitor banks to a desired set voltage. means, bank switching means connected between the lamp and the plurality of capacitor banks for switching the capacitor bank to supply power to the lamp at regular intervals in a preset sequence; A laser power supply device comprising: (2) switching means connected between a DC power source and each of the capacitor banks; voltage detection means for detecting the voltage of each of the capacitor banks; 2. The laser power supply device according to claim 1, further comprising: charging control means for controlling said switching means to perform charging so that a voltage detection value from the voltage detection means matches a voltage setting value. (3) The laser power supply device according to claim 1, further comprising the capacitor bank having a capacitance corresponding to each set voltage.