# US 2019/0356109 A1 · Laser diode-driving power supply and laser machining apparatus

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- Number: US 2019/0356109 A1
- Document ID: US20190356109A1
- Status: Published application
- Kind: A1
- Application number: 16/342,995
- Filed: 2017-04-17
- Published: 2019-11-21
- Earliest claimed: 2017-04-17
- Assignees: Mitsubishi Electric Corporation
- Applicants: Mitsubishi Electric Corporation
- Inventors: Shingo TSUDA; Takeshi MORIMOTO; Taichiro TAMIDA; Teruaki FUKUOKA; Hiroshi IKARASHI; Akihiko IWATA
- Web page: https://patentgrep.com/patent/US20190356109A1

## CPC

- H02M 3/33576: {having at least one active switching element at the secondary side of an isolation transformer}
- B23K 26/0626: {Energy control of the laser beam (B23K26/0622 takes precedence)}
- H01S 5/0428: {for applying pulses to the laser}
- H01S 5/4018: {Lasers electrically in series}
- H02M 1/08: Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M 3/33523: {with galvanic isolation between input and output of both the power stage and the feedback loop}
- H02M 3/33573: {Full-bridge at primary side of an isolation transformer}
- H01S 5/06825: {Protecting the laser, e.g. during switch-on/off, detection of malfunctioning or degradation}
- H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P)
- B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL

## Abstract

A laser diode-driving power supply includes a constant current source that supplies current to LDs, a switching element connected in parallel to the LDs, and a control unit that controls the constant current source and performs on-off control of the switching element. The control unit compares a first current command value and a second current command value for controlling current output from the constant current source, and when the second current command value input after the first current command value is smaller than the first current command value, applies to the LDs a voltage in the range of a voltage at which current flows through the LDs to a voltage less than the lasing threshold of the LDs when there is no output from the LDs.

## Claims

### Claim 1

A laser diode-driving power supply, comprising:
a constant current source to supply current to laser diodes;
a switching element connected in parallel to the laser diodes; and
a control circuit to control the constant current source and perform on-off control of the switching element,
wherein the control circuit compares a first current command value and a second current command value for controlling current output from the constant current source, and
when the second current command value input after the first current command value is smaller than the first current command value, the control circuit applies to the laser diodes a voltage in a range of a voltage at which current flows through the laser diodes to a voltage less than a lasing threshold of the laser diodes when there is no output from the laser diodes.

### Claim 2 (depends on 1)

The laser diode-driving power supply according to claim 1, wherein the control circuit applies a drive signal corresponding to a voltage in a range of a gate threshold voltage to a gate saturation voltage to the switching element when there is no output from the laser diodes.

### Claim 3 (depends on 2)

The laser diode-driving power supply according to claim 2, wherein the control circuit maintains a value of the drive signal constant.

### Claim 4 (depends on 2)

The laser diode-driving power supply according to claim 2, wherein a value of the drive signal is changed to a lasing threshold voltage in response to changes in a characteristic of the laser diodes.

### Claim 5 (depends on 1)

The laser diode-driving power supply according to claim 1, wherein the control circuit applies a drive signal changing from small to large to the switching element when there is no output from the laser diodes.

### Claim 6 (depends on 1)

A laser machining apparatus comprising the laser diode-driving power supply according to claim 1.

### Claim 7 (depends on 2)

A laser machining apparatus comprising the laser diode-driving power supply according to claim 2.

### Claim 8 (depends on 3)

A laser machining apparatus comprising the laser diode-driving power supply according to claim 3.

### Claim 9 (depends on 4)

A laser machining apparatus comprising the laser diode-driving power supply according to claim 4.

### Claim 10 (depends on 5)

A laser machining apparatus comprising the laser diode-driving power supply according to claim 5.