Laser driving device and laser marking device

Abstract

To provide a laser drive device capable of reducing power consumption.SOLUTION: A laser drive device 9 includes a voltage conversion unit 92, a transistor 951, a detection unit 96, and a processing unit 94. The voltage conversion unit 92 boosts an input voltage Vin to a DC voltage Vdc higher than the input voltage Vin and outputs the DC voltage Vdc to a semiconductor laser 52. The transistor 951 is connected to the semiconductor laser 52 and adjusts a magnitude of the current flowing to the semiconductor laser 52. The detection unit 96 detects a voltage between terminals of the transistor 951. The processing unit 94 controls the magnitude of the DC voltage Vdc on the basis of the detection result by the detection unit 96.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present disclosure generally relates to a laser driving device and a laser marking device, and more particularly to a laser driving device that causes a semiconductor laser to emit light, and a laser marking device that includes the laser driving device. [Background technology]

[0002] Patent Document 1 describes a marking device. The marking device described in Patent Document 1 has an illumination device that illuminates an object. The illumination device has a light source and an illumination element that receives a light beam from the light source and emits an illumination light beam. The light source emits a light beam under the control of a circuit board. The light beam that is incident on an illumination mirror, which is an illumination element, is reflected radially by the outer peripheral surface of the illumination mirror. The light beam reflected from the illumination mirror constitutes an illumination light beam that is illuminated on an object such as a wall or ceiling. The illumination light beam is emitted in a direction perpendicular to the central axis of the illumination mirror. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-152193 Summary of the Invention [Problem to be solved by the invention]

[0004] In a laser marking device such as the marking device described in Patent Document 1, it is sometimes desirable to reduce power consumption.

[0005] An object of the present disclosure is to reduce power consumption. [Means for solving the problem]

[0006] A laser driving device according to one aspect of the present disclosure includes a voltage conversion unit, a transistor, a detection unit, and a processing unit. The voltage conversion unit boosts an input voltage to a DC voltage higher than the input voltage and outputs the DC voltage to a semiconductor laser. The transistor is connected to the semiconductor laser and adjusts the magnitude of a current flowing through the semiconductor laser. The detection unit detects a voltage between terminals of the transistor. The processing unit controls the magnitude of the DC voltage based on the detection result of the detection unit. The processing unit controls the magnitude of the DC voltage so that it matches one of a plurality of preset target voltage values. When the inter-terminal voltage increases and exceeds a first threshold, the processing unit decreases the magnitude of the DC voltage, and when the inter-terminal voltage decreases and becomes equal to or less than a second threshold, the processing unit increases the magnitude of the DC voltage. The first threshold is greater than the second threshold.

[0007] A laser driving device according to one aspect of the present disclosure includes a voltage conversion unit, a detection unit, and a processing unit. The voltage conversion unit boosts an input voltage to a DC voltage higher than the input voltage and outputs the DC voltage to a semiconductor laser. The detection unit detects a voltage between terminals of the semiconductor laser. The processing unit controls the magnitude of the DC voltage based on the detection result of the detection unit. The processing unit controls the magnitude of the DC voltage so that it matches one of a plurality of preset target voltage values. When the inter-terminal voltage increases and exceeds a first threshold, the processing unit decreases the magnitude of the DC voltage, and when the inter-terminal voltage decreases and becomes equal to or less than a second threshold, the processing unit increases the magnitude of the DC voltage. The first threshold is greater than the second threshold.

[0008] A laser driving device according to one aspect of the present disclosure includes a voltage conversion unit, a detection unit, and a processing unit. The voltage conversion unit boosts an input voltage to a DC voltage higher than the input voltage and outputs the DC voltage to a semiconductor laser. The detection unit detects a current flowing through the semiconductor laser. The processing unit controls the magnitude of the DC voltage based on the detection result of the detection unit. The processing unit controls the magnitude of the DC voltage so that it matches one of a plurality of preset target voltage values. The processing unit decreases the magnitude of the DC voltage when the current increases and exceeds a first threshold, and increases the magnitude of the DC voltage when the current decreases and becomes equal to or less than a second threshold. The first threshold is greater than the second threshold.

[0009] A laser driving device according to one aspect of the present disclosure includes a voltage conversion unit, a transistor, a detection unit, and a processing unit. The voltage conversion unit boosts an input voltage to a DC voltage higher than the input voltage and outputs the DC voltage to a semiconductor laser. The transistor is connected to the semiconductor laser and adjusts the magnitude of the current flowing through the semiconductor laser. The detection unit detects the temperature of the semiconductor laser or the transistor. The processing unit controls the magnitude of the DC voltage based on the detection result of the detection unit. The processing unit controls the magnitude of the DC voltage so that the magnitude of the DC voltage matches one of a plurality of preset target voltage values. The processing unit decreases the magnitude of the DC voltage when the temperature increases and exceeds a first threshold, and increases the magnitude of the DC voltage when the temperature decreases and becomes equal to or lower than a second threshold. The first threshold is greater than the second threshold.

[0010] A laser marking device according to one aspect of the present disclosure includes the laser driving device according to any of the above aspects, and an optical system that converts light emitted from the semiconductor laser into linear light. [Effects of the Invention]

[0011] The present disclosure has the advantage of making it possible to reduce power consumption. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view of a laser marking device according to an embodiment with legs opened. [Figure 2] FIG. 2 is a perspective view of the laser marking device with legs closed. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a perspective view of the internal configuration of the laser marking device. [Figure 5] FIG. 5 is a perspective view of the optical body of the laser marker. [Figure 6] FIG. 6 is an exploded perspective view of a power supply-equipped leg of the laser marker. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. [Figure 8] FIG. 8 is a circuit diagram of a laser driving device provided in the laser marking device. [Figure 9] FIG. 9 is a circuit diagram of a laser driving device provided in the laser marking device of the first modified example. [Figure 10] FIG. 10 is a circuit diagram of a laser driving device provided in the laser marking device of the second modification. [Figure 11] FIG. 11 is a circuit diagram of a laser driving device provided in the laser marking device of the third modification. DETAILED DESCRIPTION OF THE INVENTION

[0013] The laser driving device and the laser marking device including the same according to the embodiment of the present disclosure will be described with reference to the drawings. The drawings described in the following embodiments are schematic diagrams, and the ratios of the sizes and thicknesses of the components in the drawings do not necessarily reflect the actual dimensional ratios.

[0014] (1) Overview The laser driving device 9 (see Figure 8) of this embodiment is provided in a laser marking device 1 (see Figures 1 to 7) which includes a semiconductor laser 52 and an optical system 53 which converts the light emitted from the semiconductor laser 52 into linear light (laser light L2, L3).

[0015] Here, the laser driving device 9 generates DC power to be supplied to the semiconductor laser 52 from input power supplied from the power supply 90. The semiconductor laser 52 is, for example, a laser diode.

[0016] As shown in FIG. 8, the laser driving device 9 includes a voltage conversion unit 92, a transistor 951, a detection unit 96, and a processing unit 94.

[0017] The voltage conversion unit 92 boosts the input voltage Vin to a DC voltage Vdc that is higher than the input voltage Vin, and outputs the DC voltage Vdc to the semiconductor laser 52.

[0018] The transistor 951 is connected to the semiconductor laser 52. Here, the transistor 951 is connected in series with the semiconductor laser 52. The transistor 951 adjusts the magnitude of the current flowing through the semiconductor laser 52. The transistor 951 has a first main electrode (collector), a second main electrode (emitter), and a control electrode (base). Here, the transistor 951 is used in the active region, and adjusts the magnitude of the current flowing through the series circuit of the semiconductor laser 52 and the transistor 951 according to the magnitude of the voltage applied to the control electrode (base).

[0019] The detection unit 96 detects the voltage across the terminals of the transistor 951. Here, the "voltage across the terminals of the transistor 951" means the collector-emitter voltage of the transistor 951.

[0020] The processing unit 94 controls the magnitude of the DC voltage Vdc based on the detection result of the detection unit 96 .

[0021] In conventional laser markers, the DC voltage generated by the voltage converter is set to a value higher than the value determined by design, taking into account manufacturing errors of parts, etc., so that the semiconductor laser can emit light in the various temperature environments in which the laser marker may be used. As a result, conventional laser markers generate excess (unnecessary) power consumption.

[0022] In contrast, in the laser driving device 9 of this embodiment, the magnitude of the DC voltage Vdc generated by the voltage conversion unit 92 is controlled (adjusted, changed) based on the voltage between the terminals of the transistor 951 detected by the detection unit 96. If the voltage between the terminals of the transistor 951 (collector-emitter voltage) is excessive, the processing unit 94 can reduce the magnitude of the DC voltage Vdc. This makes it possible to adjust the magnitude of the DC voltage Vdc to the minimum level necessary for the semiconductor laser 52 to emit light at a desired brightness, thereby suppressing excess power consumption. As a result, the laser driving device 9 of this embodiment can reduce power consumption.

[0023] (2) Details Hereinafter, the laser driving device 9 according to this embodiment and the laser marking device 1 equipped with the same will be described in detail with reference to the drawings.

[0024] (2.1) Laser level First, the structure of the laser marking device 1 will be described with reference to Figures 1 to 8. In the following description, the top, bottom, left, right, front and back of the laser marking device 1 will be basically defined as the top, bottom, left, right, front and back of the laser marking device 1 when the laser marking device 1 is installed on a horizontal installation surface.

[0025] As shown in FIG. 1, a laser marking device 1 has multiple (e.g., three) legs 3. With the legs 3 spread apart, the laser marking device 1 is placed on an installation surface, such as the ground or floor, at a work site (e.g., a housing construction site or an electrical work site). When installed on an installation surface at the work site, the laser marking device 1 emits three laser beams: a point beam L1, a horizontal line beam L2 that spreads horizontally in a fan-like shape, and a vertical line beam L3 that spreads vertically. The point beam L1 is emitted vertically upward, the horizontal line beam L2 is emitted forward in a horizontal direction, and the vertical line beam L3 is emitted forward in a vertical direction. These point beams L1, horizontal line beam L2, and vertical line beam L3 are used as reference points and reference lines to be marked on walls and ceilings during work at the work site (e.g., housing construction or electrical work). Hereinafter, the point beam L1, horizontal line beam L2, and vertical line beam L3 may be collectively referred to as laser beams L1-L3.

[0026] As shown in Figure 1, the laser marking device 1 comprises a device main body 2 and multiple (three) legs 3. The device main body 2 is a part for emitting laser beams L1 to L3. The multiple legs 3 are parts for supporting the device main body 2 on an installation surface. As shown in Figure 2, the laser marking device 1 can be easily carried by closing the multiple legs 3 to form a rod shape.

[0027] As shown in FIGS. 1 and 3, the device body 2 includes a first housing 4, an optical body 5, a support member 6, and a detection mechanism 7.

[0028] As shown in FIGS. 1 and 3, the first housing 4 includes a body 41 and a base .

[0029] The body 41 houses the optical body 5, the support member 6, and the detection mechanism 7. The body 41 is formed of, for example, a light-blocking resin. The body 41 is, for example, substantially cylindrical, and includes a peripheral wall portion 411, an upper wall portion 412, and a bottom portion 413 (see FIG. 3).

[0030] The peripheral wall portion 411 is tubular (for example, cylindrical). The upper wall portion 412 is provided on the peripheral wall portion 411 so as to close an upper opening of the peripheral wall portion 411, and is, for example, plate-shaped (for example, disk-shaped). The bottom portion 413 is provided on the peripheral wall portion 411 so as to close a lower opening of the peripheral wall portion 411, and is, for example, plate-shaped (here, disk-shaped). The outer diameter of the lower portion of the body 41 is smaller than the outer diameter of the upper portion of the body 41.

[0031] The body 41 has three transmission windows (first transmission window 401 to third transmission window 403) (see FIGS. 1 to 3). The first transmission window 401 is a transmission window through which the point light L1 is emitted. The first transmission window 401 is, for example, a substantially circular transmission window, and is provided in the center of an upper wall portion 412 of the body 41. The second transmission window 402 is a transmission window through which the horizontal line light L2 is emitted. The second transmission window 402 is, for example, a horizontally elongated rectangular transmission window, and is provided in a peripheral wall portion 411 of the body 41. The third transmission window 403 is a transmission window through which the vertical line light L3 is emitted. The third transmission window 403 is, for example, a vertically elongated rectangular transmission window, and is provided across the upper wall portion 412 and the peripheral wall portion 411 of the body 41. The three transmission windows 401 to 403 are formed of a transparent material (resin or glass).

[0032] The base 42 is fixed to the lower part of the body 41. A plurality of legs 3 are rotatably connected to the base 42 (see FIGS. 1 and 2).

[0033] The base 42 is formed of, for example, a light-shielding resin. The base 42 is tubular (for example, cylindrical) with an open upper end and a bottom. The lower part of the body 41 is inserted into the upper opening of the base 42 and fixed thereto, thereby fixing the base 42 to the body 41 (see FIG. 3).

[0034] The optical body 5 is a part that generates and emits the laser beams L1 to L3. As shown in FIGS. 3 to 5, the optical body 5 includes a case 51, a semiconductor laser 52, an optical system 53, a holder 54, and a vertical support portion 55.

[0035] As described above, the semiconductor laser 52 is a laser diode. The semiconductor laser 52 emits laser light L0 (see FIG. 5), which is the source of the laser light L1 to L3, to the optical system 53. As shown in FIGS. 3 and 4, the semiconductor laser 52 is mounted (disposed) on a first substrate 56.

[0036] The holder 54 positions and holds the semiconductor laser 52 below the optical system 53 (more specifically, below the vertical support portion 55).

[0037] The optical system 53 is disposed above the semiconductor laser 52 (more specifically, above the vertical support portion 55). As shown in FIG. 5, the optical system 53 generates laser beams L1 to L3 from the laser beam L0 emitted from the semiconductor laser 52.

[0038] As shown in FIGS. 4 and 5 , the optical system 53 includes a first beam splitter 531, a second beam splitter 532, a first output lens 533, and a second output lens 534. The first beam splitter 531 transmits a portion of the laser beam L0 from the semiconductor laser 52 and causes it to enter the second beam splitter 532, and reflects the remaining portion of the laser beam L0 and causes it to enter the first output lens 533. The first output lens 533 converts the laser beam L0 from the first beam splitter 531 into a horizontal line beam L2 and outputs the horizontal line beam L2. The second beam splitter 532 transmits a portion of the laser beam L0 from the first beam splitter 531 and outputs the vertical line beam L1 as a point beam L1, and reflects the remaining portion of the laser beam L0 and causes it to enter the second output lens 534. The second output lens 534 converts the laser beam L0 from the second beam splitter 532 into a vertical line beam L3 and outputs the vertical line beam L3.

[0039] The vertical support portion 55 supports the case 51 while being supported by the support member 6 of the device body 2. As shown in FIGS. 4 and 5, the vertical support portion 55 has a first shaft portion 551 supported by the support member 6 and a second shaft portion 552 that supports the case 51. More specifically, as shown in FIG. 3, the vertical support portion 55 is supported by the support member 6 so as to be swingable about the first shaft portion 551 and supports the case 51 so as to be swingable about the second shaft portion 552 so that the case 51 hangs down in the vertical direction. This allows the optical body 5 to always hang down in the vertical direction regardless of the inclination of the device body 2. This allows the optical body 5 to always emit the laser beams L1 to L3 in accurate directions (vertically upward, forward horizontal, and forward vertical).

[0040] As shown in FIG. 5, the vertical support unit 55 is disposed, for example, between the holder 54 and the optical system 53. The vertical support unit 55 has, for example, a rectangular parallelepiped base 553, a pair of first shafts 551, and a pair of second shafts 552. The base 553 has, for example, a substantially rectangular parallelepiped shape. The base 553 has a through-hole 554 that allows the laser light L0 from the semiconductor laser 52 to pass therethrough in the vertical direction. The pair of first shafts 551 protrude in the front-rear direction from both front and rear side surfaces of the base 553. The pair of first shafts 551 protrude to the outside of the case 51 through a pair of openings 511 (see FIG. 4) in the case 51 and are rotatably supported by a pair of bearings 61 of the support member 6 (see FIG. 3). The pair of second shafts 552 protrude in the left-right direction from both left and right side surfaces of the base 553 and are rotatably supported by a pair of bearings 512 (see FIG. 4) in the case 51. The axial direction (front-rear direction) of the first shaft portion 551 and the axial direction (left-right direction) of the second shaft portion 552 are perpendicular to each other.

[0041] As shown in Figures 4 and 5, case 51 houses semiconductor laser 52, optical system 53, holder 54, and vertical support part 55. Case 51 is, for example, in the shape of a long, vertical rod with an inclined upper surface. Optical system 53 is disposed in the upper part inside case 51. Vertical support part 55 is disposed below optical system 53 inside case 51. Semiconductor laser 52 is disposed below vertical support part 55 inside case 51 via holder 54.

[0042] As shown in FIG. 4, the case 51 has three windows (first window 513 to third window 515). The first window 513 to third window 515 are openings formed in the case 51. The first window 513 is a window through which the point light L1 is emitted, and is provided on the inclined top surface of the case 51. The second window 514 is a window through which the horizontal line light L2 is emitted, and is provided on the side surface of the case 51. The third window 515 is a window through which the vertical line light L3 is emitted, and is provided on the side surface of the case 51. The second window 514 and the third window 515 are provided on the side surface of the case 51 that faces the inclined top surface of the case 51.

[0043] As shown in FIG. 3 , the support member 6 is fixed to the inner circumferential surface of the body 41 and rotatably supports the pair of first shaft portions 551 of the vertical support portion 55. The support member 6 has an annular portion having a central opening that penetrates vertically, and a pair of bearings 61. The annular portion is fixed to the inner circumferential surface of the body 41. The pair of bearings 61 are components that rotatably support the pair of first shaft portions 551 of the optical body 5 and are fixed to the annular portion. With the optical body 5 inserted into the central opening of the annular portion and hanging down so as to be swingable, the pair of first shaft portions 551 of the optical body 5 are rotatably supported by the pair of bearings 61. In this way, the support member 6 supports the optical body 5 so as to hang down so as to be swingable around the first shaft portions 551.

[0044] The detection mechanism 7 detects whether the lower end of the optical body 5 contacts the inner circumferential surface of the body 41. As shown in FIG. 3 , the detection mechanism 7 has a first contact portion 71 and a second contact portion 72. The first contact portion 71 is a metal component (e.g., a cylindrical component). The first contact portion 71 is fixed to the lower end of the optical body 5. The second contact portion 72 is a metal annular component (e.g., a cylindrical component with a bottom). The second contact portion 72 is disposed at the bottom of the body 41. In this arrangement, the second contact portion 72 is disposed so as to surround the outer periphery of the first contact portion 71 fixed to the lower end of the optical body 5. As a result, when the lower end of the optical body 5 contacts the inner circumferential surface of the body 41, the first contact portion 71 and the second contact portion 72 are electrically connected to each other. In this embodiment, the laser level 1 includes a detection circuit that detects electrical contact between the first contact portion 71 and the second contact portion 72. When the detection circuit detects electrical contact between the first contact portion 71 and the second contact portion 72, it stops the semiconductor laser 52 in the optical body 5 from emitting light.

[0045] In other words, if the lower end of the optical body 5 comes into contact with the inner circumferential surface of the body 41, the optical body 5 will no longer be able to hang down accurately in the vertical direction. In this case, the laser marking device 1 of this embodiment stops the emission of the semiconductor laser 52 inside the optical body 5. In this way, the laser marking device 1 of this embodiment uses the detection mechanism 7 to detect whether the lower end of the optical body 5 has come into contact with the inner circumferential surface of the body 41, and based on the detection result of the detection mechanism 7, the detection circuit stops the emission of the semiconductor laser 52 inside the optical body 5.

[0046] As shown in FIG. 1, the base 42 is fixed to the lower part of the body 41. A plurality of legs 3 are rotatably connected to the base 42. The base 42 is, for example, cylindrical with one end (upper end) open and the other end (lower end) having a bottom. The lower part of the body 41 is inserted into and fixed to the inside of the base 42, whereby the base 42 is fixed to the lower part of the body 41 (see FIG. 3). A lower peripheral edge 421 (see FIG. 2) of the bottom part of the base 42 is rotatably connected to the plurality of legs 3.

[0047] The multiple (e.g., three) legs 3 are members for supporting the device main body 2 on an installation surface, as shown in Fig. 1. The multiple legs 3 are made up of multiple segments obtained by dividing a tubular body (e.g., a cylindrical body) into multiple segments (the same number as the number of legs 3) in the circumferential direction, as shown in Figs. 1 and 2.

[0048] 1 and 2, each of the multiple legs 3 has a leg body 31 and a connecting protrusion 32. The leg body 31 has substantially the same shape as one of multiple divided bodies obtained by equally dividing a tubular body (e.g., a cylindrical body) into multiple parts (the same number as the number of legs 3) in the circumferential direction. The connecting protrusion 32 protrudes upward from the center of the upper surface of the leg body 31.

[0049] The multiple legs 3 are rotatably connected to the lower peripheral edge 421 of the bottom of the base 42. Each of the multiple legs 3 is rotatable around its first end (upper end) between a direction along the center line M1 of the base 42 (i.e., the first housing 4) (see FIG. 2) and a direction along the inclined line M2 (see FIG. 1). The center line M1 is an imaginary line that passes through the center of the base 42 (i.e., the first housing 4). The inclined line M2 is an imaginary line that is inclined toward the outer periphery of the base 42 with respect to the center line M1 of the base 42.

[0050] More specifically, as shown in FIG. 2 , a lower peripheral edge 421 of the bottom of the base 42 is provided with a plurality of (e.g., three) connecting recesses 422 that correspond one-to-one to the plurality of (e.g., three) leg portions 3. The connecting protrusions 32 of the corresponding leg portions 3 are disposed in each of the plurality of connecting recesses 422. A rotation shaft 423 is disposed inside the connecting recesses 422. The rotation shaft 423 is parallel to a tangent to the connecting recess 422 at the location of the connecting recess 422 in the outer peripheral contour (e.g., circular) of the base 42. The connecting protrusions 32 of the leg portions 3 are rotatably coupled to the rotation shaft 423. As a result, each of the plurality of legs 3 is coupled to the lower peripheral edge 421 of the base 42 so as to be rotatable around the first end (connecting protrusion 32) between a direction along the center line M1 of the base 42 (first housing 4) and a direction along the inclined line M2.

[0051] The multiple legs 3 can be in an open position (along the inclined line M2; see FIG. 1) or a closed position (along the center line M1; see FIG. 2). When the multiple legs 3 are in an open position, the laser marker 1 can be placed upright by placing the second ends (lower ends) of the multiple legs 3 on the installation surface. When the multiple legs 3 are in a closed position, the multiple legs 3 are bundled together and extend along the center line M1 of the device body 2, giving the overall shape of the laser marker 1 a straight rod shape. This improves the portability of the laser marker 1.

[0052] One of the plurality of legs 3 is a powered leg 300. As shown in FIGS. 1 and 6, the powered leg 300 further includes a power supply case 33, a power supply holder 34, and a second board 35.

[0053] The second substrate 35 is housed in a housing recess 311 provided on the inner main surface of the leg body 31 of the powered leg 300. On the second substrate 35, at least a transistor 951 is mounted.

[0054] The power supply holder 34 is a member that detachably holds the power supply 90. The power supply 90 is a power source for emitting light and controlling the semiconductor laser 52, and is, for example, a dry cell battery (e.g., a size AA battery). The power supply holder 34 has a base plate 341 and a pair of clamping plates 342 and 343. The base plate 341 is, for example, a rectangular plate and is fixed to the leg main body 31 so as to close the opening of the accommodating recess 311. The pair of clamping plates 342 and 343 are parts for holding the power supply 90 in the vertical direction and protrude from the main surface of the base plate 341 opposite the accommodating recess 311 side, with a predetermined gap (the length of the dry cell battery) between them in the up-down direction. Terminals for electrical contact with the positive or negative pole of the power supply 90 are arranged on the opposing surfaces of the pair of clamping plates 342 and 343. The power supply holder 34 holds a plurality of (for example, three) dry batteries as the power supply 90 by sandwiching them between a pair of clamping plates 342, 343 in a stacked parallel arrangement.

[0055] The power supply case 33 is a substantially rectangular box-like shape with one surface (opening surface 330) open. The power supply case 33 houses the power supply holder 34 inside the power supply case 33 and is fixed to the inner main surface of the leg main body 31 so that the opening surface 330 of the power supply case 33 is closed by the inner main surface of the leg main body 31.

[0056] The power supply case 33 is divided into two parts, an upper part and an lower part. That is, the power supply case 33 comprises an upper fixed case part 331 and a lower detachable cover part 332. The fixed case part 331 is fixed to the inner main surface of the leg main body 31. The detachable cover part 332 is detachably attached to the inner main surface of the leg main body 31.

[0057] In the laser marker 1, the power supply holder 34 inside the power supply case 33 can be exposed to the outside by opening the multiple legs 3 (see FIG. 1) and removing the detachable cover part 332 from the leg body 31. In this exposed state, it is possible to replace the power supply (dry cell battery) held in the power supply holder 34. After battery replacement, the detachable cover part 332 is detachably attached to the inner main surface of the leg body 31.

[0058] Furthermore, in the laser marking device 1, when the multiple legs 3 are closed, the power supply case 33 of the powered leg 300 is housed inside the cylindrical body formed by the multiple legs 3 (see Figure 2).

[0059] In this embodiment, the leg body 31 and the power supply case 33 of the powered leg 300 form a housing (second housing) 36 that houses the transistor 951.

[0060] (2.2) Laser driver The laser driving device 9 provided in the laser marking device 1 will be described with reference to FIG.

[0061] 8, the laser driving device 9 includes a pair of input terminals 911, 912, a voltage conversion unit 92, a reference value generation unit 93, a processing unit 94, a light emission circuit 95, a detection unit 96, and a pair of output terminals 971, 972. In the following, as necessary, the input terminal 911 may be referred to as the "high potential side input terminal 911," the input terminal 912 as the "low potential side input terminal 912," the output terminal 971 as the "high potential side output terminal 971," and the output terminal 972 as the "low potential side output terminal 972."

[0062] A power supply 90 is connected between the pair of input terminals 911, 912. For example, three dry batteries connected in series are connected between the pair of input terminals 911, 912 as the power supply 90. An input voltage Vin is applied from the power supply 90 between the pair of input terminals 911, 912.

[0063] The voltage conversion unit 92 is connected to a pair of input terminals 911, 912. The voltage conversion unit 92 receives an input voltage Vin via the pair of input terminals 911, 912, and boosts the received input voltage Vin to a DC voltage Vdc that is higher than the input voltage Vin. The voltage conversion unit 92 outputs the DC voltage Vdc from a pair of output terminals.

[0064] The voltage conversion unit 92 includes a choke coil 921, a diode 922, a switching element 923 (transistor), a smoothing capacitor 924, a switching control unit 925, and a signal input terminal 926. The choke coil 921, the diode 922, the switching element 923, and the smoothing capacitor 924 configure a voltage conversion circuit 920.

[0065] A first end of choke coil 921 is connected to high-potential side input terminal 911. A second end of choke coil 921 is connected to an anode of diode 922. A cathode of diode 922 is connected to low-potential side input terminal 912 via smoothing capacitor 924. A first main electrode (e.g., collector) of switching element 923 is connected to the second end of choke coil 921. A second main electrode (e.g., emitter) of switching element 923 is connected to low-potential side input terminal 912.

[0066] The voltage conversion circuit 920 is a step-up chopper that converts an input voltage Vin applied between a pair of input terminals 911 and 912 into a DC voltage Vdc.

[0067] A reference signal Sin indicating a reference value is input to the signal input terminal 926 .

[0068] The switching control unit 925 controls the switching of the switching element 923. The switching control unit 925 is realized by, for example, an IC (Integrated Circuit) or the like.

[0069] The switching control unit 925 receives a reference signal Sin via a signal input terminal 926. The switching control unit 925 controls the duty of the switching element 923 (transistor) so that a reference value indicated by the reference signal Sin matches a predetermined specified value. As will be described later, the reference value is a value proportional to the magnitude of the DC voltage Vdc. Therefore, by the switching control unit 925 controlling the duty of the switching element 923 so that the reference value matches the specified value, the magnitude of the DC voltage Vdc can be controlled to a constant value proportional to the specified value. If the reference value is smaller than the specified value, the switching control unit 925 increases the duty of the switching element 923 to increase the magnitude of the DC voltage Vdc, and if the reference value is greater than the specified value, the switching control unit 925 decreases the duty of the switching element 923 to decrease the magnitude of the DC voltage Vdc.

[0070] The reference value generating unit 93 generates a reference value proportional to the magnitude of the DC voltage Vdc.

[0071] As shown in FIG. 8, the reference value generating unit 93 includes a first resistor 931, a second resistor 932, a third resistor 933, a fourth resistor 934, a first switch 935, and a second switch 936.

[0072] A first terminal of the first resistor 931 is connected to the high-potential side output terminal of the voltage conversion unit 92. The second resistor 932, a series circuit of the third resistor 933 and the first switch 935, and a series circuit of the fourth resistor 934 and the second switch 936 are connected in parallel to each other to form a parallel circuit 930. A second terminal of the first resistor 931 is connected to the first terminal of the parallel circuit 930. A second terminal of the parallel circuit 930 is connected to the low-potential side output terminal of the voltage conversion unit 92. That is, the reference value generation unit 93 includes a series circuit (hereinafter also referred to as a "voltage divider circuit") of the first resistor 931 and the parallel circuit 930. This voltage divider circuit is connected between a pair of output terminals of the voltage conversion unit 92.

[0073] In the reference value generating unit 93, a connection point N0 between the first resistor 931 and the parallel circuit 930 in the voltage dividing circuit is connected to a signal input terminal 926 of the voltage converting unit 92. The reference value generating unit 93 outputs the potential of the connection point N0 (the voltage between the connection point N0 and ground) as a reference signal Sin to the signal input terminal 926. The magnitude of the potential of the connection point N0 is the reference value. In the reference value generating unit 93, the resistance value R0 of the parallel circuit 930 changes as the first switch 935 and the second switch 936 are turned on and off, thereby changing the reference value. In the following description, for convenience, the resistance value of the parallel circuit 930 is represented as R0, the resistance value of the first resistor 931 as R1, the resistance value of the second resistor 932 as R2, the resistance value of the third resistor 933 as R3, the resistance value of the fourth resistor 934 as R4, and the magnitude of the DC voltage Vdc as |Vdc|.

[0074] When the first switch 935 and the second switch 936 are both off, the resistance value R0 of the parallel circuit 930 is R2. On the other hand, when the first switch 935 is on and the second switch 936 is off, the resistance value R0 of the parallel circuit 930 is R2·R3 / (R2+R3). For convenience, if R2·R3 / (R2+R3) is defined as "R5," R5 is smaller than R2. Furthermore, when the first switch 935 and the second switch 936 are both on, the resistance value R0 of the parallel circuit 930 is R2·R3·R4 / (R2·R3+R2·R4+R3·R4). For convenience, if R2·R3·R4 / (R2·R3+R2·R4+R3·R4) is defined as "R6," R6 is smaller than R5.

[0075] Since the reference value is expressed as R0·|Vdc| / (R1+R0), if the magnitude of Vdc |Vdc| is constant, the reference value will change according to changes in the resistance value R0 of the parallel circuit 930 (becoming smaller as the resistance value R0 becomes smaller).

[0076] As described above, the switching control unit 925 of the voltage conversion unit 92 controls the duty of the switching element 923 (transistor) so that the reference value indicated by the reference signal Sin coincides with a predetermined specified value. That is, when the resistance value R0 of the parallel circuit 930 changes as a result of the first switch 935 or the second switch 936 of the parallel circuit 930 being switched on and off, the switching control unit 925 changes the duty of the switching element 923 to change the magnitude of the DC voltage Vdc so that the reference value is maintained at a predetermined value. Specifically, when the first switch 935 or the second switch 936 is switched from off to on and the resistance value R0 of the parallel circuit 930 decreases, the switching control unit 925 increases the duty of the switching element 923 to increase the magnitude of the DC voltage Vdc. Furthermore, when the first switch 935 or the second switch 936 is switched from on to off and the resistance value R0 of the parallel circuit 930 increases, the switching control unit 925 reduces the duty of the switching element 923 to reduce the magnitude of the DC voltage Vdc.

[0077] As a result, even if the resistance value R0 of the parallel circuit 930 changes, the reference value is maintained at a default value. On the other hand, the magnitude of the DC voltage Vdc generated by the voltage conversion unit 92 changes in accordance with the change in the resistance value R0 of the parallel circuit 930 (specifically, the DC voltage Vdc decreases when the resistance value R0 increases, and increases when the resistance value R0 decreases). That is, in the laser driving device 9 of this embodiment, the magnitude of the DC voltage Vdc generated by the voltage conversion unit 92 can be changed by changing the reference value input to the switching control unit 925 without changing the processing operation of the switching control unit 925.

[0078] Hereinafter, for convenience, the magnitude of the DC voltage Vdc when the first switch 935 and the second switch 936 are both on may be referred to as the "first voltage value," the magnitude of the DC voltage Vdc when the first switch 935 is on and the second switch 936 is off may be referred to as the "second voltage value," and the magnitude of the DC voltage Vdc when the first switch 935 is on and the second switch 936 is off may be referred to as the "third voltage value." The first voltage value is greater than the second voltage value, which is greater than the third voltage value. Although not particularly limited, for example, the first voltage value is 8 V, the second voltage value is 7 V, and the third voltage value is 6 V (the first resistance value R1 to the fourth resistance value R4 and the above-mentioned default values, etc. are set so that this occurs).

[0079] The processing unit 94 is realized by, for example, an integrated circuit (IC), a field programmable gate array (FPGA), or the like.

[0080] The processing unit 94 controls the magnitude of the DC voltage Vdc generated by the voltage conversion unit 92. The processing unit 94 controls the magnitude of the DC voltage Vdc based on the detection result of the detection unit 96.

[0081] The processing unit 94 changes the magnitude of the DC voltage Vdc by changing the reference value. Here, the processing unit 94 controls the on / off of the first switch 935 and the second switch 936 of the reference value generation unit 93. The processing unit 94 changes the reference value by switching the first switch 935 and the second switch 936 of the reference value generation unit 93 on and off, thereby changing the magnitude of the DC voltage Vdc. When it is desired to increase the magnitude of the DC voltage Vdc, the processing unit 94 switches either the first switch 935 or the second switch 936 from off to on. When it is desired to decrease the magnitude of the DC voltage Vdc, the processing unit 94 switches either the first switch 935 or the second switch 936 from on to off.

[0082] 8, a pair of input terminals of the light-emitting circuit 95 is connected to a pair of output terminals of the voltage conversion unit 92 via the reference value generation unit 93. The pair of output terminals of the light-emitting circuit 95 is connected to a pair of output terminals 971, 972. The high-potential side output terminal of the light-emitting circuit 95 has the same potential as the high-potential side input terminal of the light-emitting circuit 95. Therefore, the high-potential side output terminal 971 has the same potential as the high-potential side output terminal of the voltage conversion unit 92.

[0083] 8, the semiconductor laser 52 is connected between a pair of output terminals 971 and 972. The anode of the semiconductor laser 52 (laser diode) is connected to the output terminal 971, and the cathode is connected to the output terminal 972.

[0084] As shown in FIG. 8, the light emitting circuit 95 includes a voltage source 950, a transistor (hereinafter also referred to as a “first transistor”) 951, a second transistor 952, a light receiving element 953, and resistors 954, 955, 956, and 957.

[0085] The first transistor 951 is a semiconductor element that controls the amount of light emitted by the semiconductor laser 52 by adjusting the magnitude of the current flowing through the semiconductor laser 52. The first transistor 951 is, for example, an NPN bipolar transistor.

[0086] The first transistor 951 has a first main electrode (e.g., collector), a second main electrode (e.g., emitter), and a control electrode (e.g., base). The first main electrode of the first transistor 951 is connected to an output terminal 972 (cathode of the semiconductor laser 52) via a detection resistor 963 (shunt resistor) for current detection. The second main electrode of the first transistor 951 is connected to the low-potential output terminal of the voltage conversion unit 92. In the laser driving device 9 of this embodiment, the detection resistor 963 may be omitted.

[0087] The first transistor 951 operates in an active region. The first transistor 951 controls the current (collector current) flowing through the first transistor 951, i.e., the current flowing through the semiconductor laser 52, in accordance with the current (base current) flowing through its control electrode.

[0088] The second transistor 952 controls the current flowing through the control electrode of the first transistor 951 in accordance with the amount of light received by the light receiving element 953. The second transistor 952 is, for example, a PNP bipolar transistor.

[0089] The second transistor 952 has a first main electrode (e.g., a collector), a second main electrode (e.g., an emitter), and a control electrode (e.g., a base). The second main electrode of the second transistor 952 is connected to a voltage source 950. The voltage source 950 outputs a DC voltage Vc having a fixed (constant) voltage value. The DC voltage Vc is generated, for example, from the output voltage of the power source 90. The first main electrode of the second transistor 952 is connected to the low-potential output terminal of the voltage conversion unit 92 via a first voltage divider circuit including resistors 954 and 955 connected in series. The output terminal of the first voltage divider circuit (a connection point N1 between the resistors 954 and 955) is connected to the control electrode of the first transistor 951.

[0090] The second transistor 952 operates in an active region. The second transistor 952 controls the current (collector current) flowing through the second transistor 952, i.e., the current flowing through the first voltage divider circuit (resistors 954 and 955), depending on the current (base current) flowing through its control electrode.

[0091] The light receiving element 953 is, for example, a photodiode. The light receiving element 953 receives light leaking from the laser light L0 emitted by the semiconductor laser 52. In this way, the light receiving element 953 detects the emission amount of the laser light L0 from the semiconductor laser 52.

[0092] The cathode of the light receiving element 953 is connected to the high potential side output terminal of the voltage conversion unit 92. The anode of the light receiving element 953 is connected to the low potential side output terminal of the voltage conversion unit 92 via a second voltage dividing circuit including resistors 956 and 957 connected in series. The output terminal of the second voltage dividing circuit (connection point N2 between resistors 956 and 957) is connected to the control electrode of the second transistor 952.

[0093] In this light-emitting circuit 95, when power is turned on, the voltage source 950 applies a DC voltage Vc to make the second transistor 952 conductive, and a base current is supplied to the first transistor 951, causing the first transistor 951 to initially conduct. As a result, a current due to the DC voltage Vdc flows through the semiconductor laser 52 and the first transistor 951. This causes the semiconductor laser 52 to emit light, emitting laser light L0.

[0094] When the semiconductor laser 52 is emitting laser light L0, if the amount of light emitted by the semiconductor laser 52 increases, the amount of light received by the light-receiving element 953 increases, the current flowing through the light-receiving element 953 increases, the voltage across the resistor 957 increases, and the potential at the connection point N2 increases. If the potential at the connection point N2 increases, the base current of the second transistor 952 decreases, the collector current of the second transistor 952 decreases, the voltage across the resistor 955 decreases, and the potential at the connection point N1 decreases. If the potential at the connection point N1 decreases, the base current of the first transistor 951 decreases, and the collector current of the first transistor 951, i.e., the current flowing through the semiconductor laser 52, decreases. This reduces the amount of light emitted by the semiconductor laser 52.

[0095] Furthermore, when the semiconductor laser 52 is emitting laser light L0 and the light emission amount of the semiconductor laser 52 decreases, the light receiving amount of the light receiving element 953 decreases, the current flowing through the light receiving element 953 decreases, the voltage across the resistor 957 decreases, and the potential at the node N2 decreases. When the potential at the node N2 decreases, the base current of the second transistor 952 increases, the collector current of the second transistor 952 increases, the voltage across the resistor 955 increases, and the potential at the node N1 increases. When the potential at the node N1 increases, the base current of the first transistor 951 increases, and the collector current of the first transistor 951, i.e., the current flowing through the semiconductor laser 52, increases. This increases the light emission amount of the semiconductor laser 52.

[0096] As described above, the light-emitting circuit 95 includes a light-receiving element 953 that receives light from the semiconductor laser 52, and a current control circuit 959 that is connected to the control electrode of the transistor 951 and controls the current flowing through the control electrode in accordance with the amount of light received by the light-receiving element 953 so that the amount of light received by the light-receiving element 953 converges to a predetermined value. The current control circuit 959 includes a voltage source 950, a second transistor 952, and resistors 954, 955, 956, and 957. The light-emitting circuit 95 (current control circuit 959) performs feedback control so that the amount of light emitted by the semiconductor laser 52 is constant. As a result, the amount of light emitted by the semiconductor laser 52 is maintained at a constant value that corresponds to the magnitude of the DC voltage Vdc.

[0097] The detector 96 detects a physical quantity that indicates the operating state of the semiconductor laser 52 or the transistor 951. Here, the detector 96 detects the voltage between the terminals of the transistor 951 as the physical quantity.

[0098] 8, the detection unit 96 includes a voltage dividing circuit 960. The voltage dividing circuit 960 is connected in parallel with the transistor 951. The voltage dividing circuit 960 is connected across the first main electrode and the second main electrode of the transistor 951.

[0099] The voltage-dividing circuit 960 includes a first voltage-dividing resistor 961 and a second voltage-dividing resistor 962. A first terminal of the first voltage-dividing resistor 961 is connected to a first main electrode of the transistor 951, a second terminal of the first voltage-dividing resistor 961 is connected to a first terminal of the second voltage-dividing resistor 962, and a second terminal of the second voltage-dividing resistor 962 is connected to a second main electrode of the transistor 951. A connection point between the first voltage-dividing resistor 961 and the second voltage-dividing resistor 962 is connected to the processing unit 94. The detection unit 96 outputs a voltage across the second voltage-dividing resistor 962 to the processing unit 94 as a detection result. Note that the voltage across the second voltage-dividing resistor 962 is proportional to the voltage across the transistor 951, and therefore, in the present disclosure, the voltage across the second voltage-dividing resistor 962 detected by the detection unit 96 is also simply referred to as the “voltage across the transistor 951.”

[0100] The processing unit 94 controls the magnitude of the DC voltage Vdc generated by the voltage conversion unit 92 based on the detection result of the detection unit 96. The processing unit 94 controls the magnitude of the DC voltage Vdc by controlling the reference value generation unit 93 (the first switch 935 and the second switch 936).

[0101] The processing unit 94 controls the magnitude of the DC voltage Vdc so that the magnitude of the DC voltage Vdc matches one of multiple preset target voltage values. The multiple target voltage values ​​include a first voltage value (8 V), a second voltage value (7 V), and a third voltage value (6 V). When the DC voltage Vdc matches the first voltage value, the processing unit 94 turns on both the first switch 935 and the second switch 936. When the DC voltage Vdc matches the second voltage value, the processing unit 94 turns on the first switch 935 and turns off the second switch 936. When the DC voltage Vdc matches the third voltage value, the processing unit 94 turns off both the first switch 935 and the second switch 936. Using multiple target voltage values ​​allows for a simpler circuit configuration than a configuration in which the target voltage value changes continuously.

[0102] An example of a method for controlling the reference value generating unit 93 (first switch 935 and second switch 936) by the processing unit 94 will be described below.

[0103] When the power is turned on, the processing unit 94 turns on the first switch 935 and the second switch 936 so that the magnitude of the DC voltage Vdc generated by the voltage conversion unit 92 becomes the first voltage value (8V), which is the maximum magnitude that can be output.

[0104] Immediately after power-on, the processing unit 94 compares the physical quantity detected by the detection unit 96 (the magnitude of the voltage between the terminals of the transistor 951) with the first reference value and the second reference value (second reference value>first reference value).

[0105] If the magnitude of the voltage across the terminals of the transistor 951 exceeds the second reference value, this means that the voltage drop between the collector and emitter of the transistor 951 is large, i.e., the magnitude of the DC voltage Vdc is excessive (the second reference value is set accordingly). In this case, the processing unit 94 turns off the second switch 936 and reduces the magnitude of the DC voltage Vdc from the first voltage value (8 V) to the second voltage value (7 V).

[0106] On the other hand, if the magnitude of the voltage between the terminals of the transistor 951 is equal to or less than the first reference value, the processing unit 94 determines that the semiconductor laser 52 is not emitting light normally. The processing unit 94 may issue a warning to the user, for example, by turning on a warning light provided in the first housing 4.

[0107] When the magnitude of the voltage between the terminals of the transistor 951 exceeds the first reference value and is equal to or less than the second reference value, the processing unit 94 maintains the on state of the first switch 935 and the second switch 936. Hereinafter, the state in which the first switch 935 and the second switch 936 are both on will also be referred to as a "both on state."

[0108] After turning off the second switch 936, the processing unit 94 compares the physical quantity detected by the detection unit 96 (the magnitude of the voltage between the terminals of the transistor 951) with the third reference value and the fourth reference value (the fourth reference value > the third reference value).

[0109] If the magnitude of the voltage between the terminals of the transistor 951 exceeds the fourth reference value, the processing unit 94 further turns off the first switch 935 to reduce the magnitude of the DC voltage Vdc from the second voltage value (7 V) to the third voltage value (6 V).

[0110] On the other hand, when the magnitude of the voltage between the terminals of the transistor 951 exceeds the third reference value and is equal to or less than the fourth reference value, the processing unit 94 maintains the first switch 935 on and the second switch 936 off. Hereinafter, the state in which the first switch 935 is on and the second switch 936 is off will also be referred to as a "one-side off state."

[0111] When the voltage between the terminals of the transistor 951 is equal to or lower than the third reference value, the processing unit 94 may again turn on the second switch 936. When turning on the second switch 936 again, the processing unit 94 may provide a predetermined delay time.

[0112] After turning off the first switch 935, the processing unit 94 compares the physical quantity detected by the detection unit 96 (the voltage between the terminals of the transistor 951) with a fifth reference value.

[0113] When the voltage between the terminals of the transistor 951 exceeds the fifth reference value, the processing unit 94 maintains the off state of the first switch 935 and the second switch 936. Hereinafter, the state in which the first switch 935 and the second switch 936 are both off will also be referred to as a "both off state."

[0114] When the voltage across the terminals of the transistor 951 is equal to or lower than the fifth reference value, the processing unit 94 may again turn on the first switch 935. When turning on the first switch 935 again, the processing unit 94 may provide a predetermined delay time.

[0115] In this way, the processing unit 94 sets the magnitude of the DC voltage Vdc at power-on to the maximum value (8V) within the selectable voltage range (here, 6V, 7V, 8V). This increases the possibility that the semiconductor laser 52 can emit the laser light L0 immediately after power-on. However, this is not limiting, and the processing unit 94 may also set the magnitude of the DC voltage Vdc at power-on to the minimum value (6V) within the selectable voltage range (here, 6V, 7V, 8V).

[0116] After the above-described initial operation is completed, the processing unit 94 controls the magnitude of the DC voltage Vdc based on the detection result of the detection unit 96.

[0117] Here, when the physical quantity (voltage between terminals of transistor 951) detected by the detection unit 96 increases and exceeds a predetermined threshold, the processing unit 94 reduces the magnitude of the DC voltage Vdc. For example, when the processing unit 94 detects that the voltage between terminals of the transistor 951 has increased and exceeded a predetermined threshold (for example, the above-mentioned second reference value) in a double-on state (a state in which the magnitude of the DC voltage Vdc is 8 V), the processing unit 94 turns off the second switch 936 and reduces the magnitude of the DC voltage Vdc to 7 V. When the processing unit 94 detects that the voltage between terminals of the transistor 951 has increased and exceeded a predetermined threshold (for example, the above-mentioned fourth reference value) in a single-off state (a state in which the magnitude of the DC voltage Vdc is 7 V), the processing unit 94 turns off the first switch 935 and reduces the magnitude of the DC voltage Vdc to 6 V.

[0118] Furthermore, when the physical quantity (voltage between the terminals of the transistor 951) detected by the detection unit 96 decreases and becomes equal to or less than a predetermined threshold, the processing unit 94 increases the magnitude of the DC voltage Vdc. For example, when the processing unit 94 detects that the voltage between the terminals of the transistor 951 has decreased and become equal to or less than a predetermined threshold (for example, the fifth reference value) in the double-off state (when the magnitude of the DC voltage Vdc is 6 V), the processing unit 94 turns on the first switch 935 to increase the magnitude of the DC voltage Vdc to 7 V. When the processing unit 94 detects that the voltage between the terminals of the transistor 951 has decreased and become equal to or less than a predetermined threshold (for example, the third reference value) in the single-off state (when the magnitude of the DC voltage Vdc is 7 V), the processing unit 94 turns on the second switch 936 to increase the magnitude of the DC voltage Vdc to 8 V.

[0119] In this way, the processing unit 94 of the laser driving device 9 reduces the magnitude of the DC voltage Vdc when the physical quantity (voltage across the transistor 951) detected by the detection unit 96 increases and exceeds the first threshold value (second reference value, fourth reference value). Furthermore, the processing unit 94 increases the magnitude of the DC voltage Vdc when the physical quantity (voltage across the transistor 951) detected by the detection unit 96 decreases and becomes equal to or less than the second threshold value (third reference value, fifth reference value). By the processing unit 94 controlling the magnitude of the DC voltage Vdc based on the voltage across the transistor 951, it becomes possible to adjust the magnitude of the DC voltage Vdc to the minimum level required for the semiconductor laser 52 to emit the laser light L0. This makes it possible for the laser driving device 9 of this embodiment to suppress excess power consumption and thereby reduce power consumption.

[0120] In the laser driving device 9 of this embodiment, the second reference value is greater than the third reference value, and the fourth reference value is greater than the fifth reference value. In other words, when the physical quantity (voltage across the transistor 951) detected by the detection unit 96 increases and exceeds the first threshold (second reference value, fourth reference value), the processing unit 94 reduces the magnitude of the DC voltage Vdc. When the physical quantity decreases and becomes equal to or less than the second threshold (third reference value, fifth reference value), the processing unit 94 increases the magnitude of the DC voltage Vdc. The first threshold is greater than the second threshold. That is, the processing unit 94 applies hysteresis when changing the magnitude of the DC voltage Vdc. This reduces the likelihood of oscillation, in which the magnitude of the DC voltage Vdc is repeatedly switched between 8V and 7V or between 7V and 6V within a short period of time.

[0121] Note that, after the semiconductor laser 52 starts emitting light, one example of a cause of a change in the detection result of the detection unit 96 (the physical quantity detected by the detection unit 96) is a change in the temperature of the semiconductor laser 52. Examples of causes of a change in the temperature of the semiconductor laser 52 include heat generation from the semiconductor laser 52 or surrounding circuit components, a change in the outside air temperature, etc.

[0122] The semiconductor laser 52 has a characteristic that, under the condition that the current flowing through the semiconductor laser 52 is constant, the forward voltage of the semiconductor laser 52 decreases as the temperature of the semiconductor laser 52 increases. Therefore, when the temperature of the semiconductor laser 52 increases, the forward voltage of the semiconductor laser 52 decreases, the voltage across the transistor 951 increases, and the physical quantity detected by the detection unit 96 increases. In this case, the processing unit 94 decreases the magnitude of the DC voltage Vdc. On the other hand, when the temperature of the semiconductor laser 52 decreases, the forward voltage of the semiconductor laser 52 increases, the voltage across the transistor 951 decreases, and the physical quantity detected by the detection unit 96 decreases. In this case, the processing unit 94 increases the magnitude of the DC voltage Vdc.

[0123] In other words, when the temperature of the semiconductor laser 52 increases and the voltage across the transistor 951 exceeds a predetermined threshold, the processing unit 94 reduces the magnitude of the DC voltage Vdc. As a result, for example, when the laser marking device 1 is used in a cold climate, if the forward voltage required for the semiconductor laser 52 to emit the laser light L0 decreases from the initial state of light emission due to heat generation by the semiconductor laser 52, etc., the processing unit 94 changes the magnitude of the DC voltage Vdc to a relatively small value. This makes it possible to reduce power consumption.

[0124] Furthermore, even if there are manufacturing errors or deterioration over time in the circuit components of the laser marking device 1, the processing unit 94 controls the magnitude of the DC voltage Vdc based on the detection results of the detection unit 96, making it possible to operate the laser driving device 9 in accordance with the actual state of the circuit components, etc. This makes it possible to reduce power consumption.

[0125] As shown in FIGS. 3 to 6 , in the laser marking device 1 of this embodiment, the semiconductor laser 52 and the transistor 951 are housed in different housings. Specifically, the semiconductor laser 52 is mounted on a first board 56 and housed in the first housing 4. Meanwhile, the transistor 951 is mounted on a second board 35 and housed in the second housing 36. The second housing 36 is a housing separate from the first housing 4. This removes the transistor 951, which is a heat source that thermally affects the semiconductor laser 52, from the first housing 4 that houses the semiconductor laser 52. This prevents the transistor 951 from causing a temperature rise in the first housing 4, and as a result, prevents a temperature rise in the semiconductor laser 52 due to heat generated by the transistor 951. By preventing a temperature rise in the semiconductor laser 52, it is possible to prevent a decrease in the light-emitting efficiency and a shortened lifespan of the semiconductor laser 52.

[0126] In the laser marking device 1 of this embodiment, the light receiving element 953 is also mounted on the first board 56 and housed in the first housing 4. On the other hand, other components in the laser driving device 9 that may become heat sources (such as the switching element 923, smoothing capacitor 924, first switch 935, second switch 936, second transistor 952, switching control section 925, and processing section 94) may be housed in the first housing 4, but are preferably housed in the second housing 36. If the components that become heat sources are housed in the second housing 36, it is possible to suppress a rise in temperature of the semiconductor laser 52, and to suppress a decrease in the light emitting efficiency and a shortened lifespan of the semiconductor laser 52.

[0127] (3) Variations The above embodiment is merely one of various embodiments of the present disclosure. The above embodiment can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. Modifications of the embodiment are listed below. The above embodiment and the modifications described below can be applied in appropriate combinations.

[0128] (3.1) Variation 1 The laser driving device 9 of this modified example will be described with reference to Fig. 9. The laser driving device 9 of this modified example differs from the laser driving device 9 of the above embodiment in the configuration of the detection unit 96. In the laser driving device 9 of this modified example, the description of the same configuration as the laser driving device 9 of the above embodiment may be omitted as appropriate.

[0129] 9, in the laser driving device 9 of this modification, the detection unit 96 detects the voltage between the terminals of the semiconductor laser 52. The "voltage between the terminals of the semiconductor laser 52" means the voltage between both ends of the semiconductor laser 52 (between the anode and cathode).

[0130] 9, the detection unit 96 includes a voltage dividing circuit 964. The voltage dividing circuit 964 is connected in parallel with the semiconductor laser 52. The voltage dividing circuit 964 is connected across the anode and cathode of the semiconductor laser 52.

[0131] The voltage-dividing circuit 964 includes a first voltage-dividing resistor 965 and a second voltage-dividing resistor 966. A first terminal of the first voltage-dividing resistor 965 is connected to a high-potential output terminal 971 (the anode of the semiconductor laser 52), a second terminal of the first voltage-dividing resistor 965 is connected to a first terminal of the second voltage-dividing resistor 966, and a second terminal of the second voltage-dividing resistor 966 is connected to a low-potential output terminal 972 (the cathode of the semiconductor laser 52). The connection point between the first voltage-dividing resistor 965 and the second voltage-dividing resistor 966 is connected to a non-inverting input terminal of an operational amplifier 967 that constitutes a differential amplifier circuit. An inverting input terminal of the operational amplifier 967 is connected to a voltage source 968 that outputs a constant voltage, and an output terminal of the operational amplifier 967 is connected to the processing unit 94. The detection unit 96 outputs a voltage obtained by subtracting the voltage across the second voltage-dividing resistor 966 from the constant voltage to the processing unit 94 as a detection result (physical quantity).

[0132] The processing unit 94 controls the magnitude of the DC voltage Vdc based on the detection result of the detection unit 96 (the voltage between the terminals of the semiconductor laser 52).

[0133] As described above, the semiconductor laser 52 has a characteristic that the forward voltage decreases as the temperature of the semiconductor laser 52 increases. Therefore, when the physical quantity detected by the detection unit 96 (the voltage obtained by subtracting the voltage across the second voltage dividing resistor from a constant voltage) increases due to a decrease in the temperature of the semiconductor laser 52 and exceeds a predetermined threshold, the processing unit 94 decreases the magnitude of the DC voltage Vdc. Furthermore, when the physical quantity detected by the detection unit 96 decreases due to an increase in the temperature of the semiconductor laser 52 and becomes equal to or less than the predetermined threshold, the processing unit 94 controls the reference value generation unit 93 to increase the magnitude of the DC voltage Vdc.

[0134] In the laser driving device 9 of this modification, the processing unit 94 also controls the magnitude of the DC voltage Vdc based on the detection result of the detection unit 96, thereby making it possible to adjust the magnitude of the DC voltage Vdc to the minimum level required for the semiconductor laser 52 to emit the laser light L0. This makes it possible to suppress excess power consumption and reduce power consumption.

[0135] (3.2) Variation 2 The laser driving device 9 of this modified example will be described with reference to Fig. 10. The laser driving device 9 of this modified example differs from the laser driving device 9 of the above embodiment in the configuration of the detection unit 96. In the laser driving device 9 of this modified example, the description of the same configuration as the laser driving device 9 of the above embodiment may be omitted as appropriate.

[0136] As shown in FIG. 10, in the laser driving device 9 of this modified example, the detection unit 96 detects the current flowing through the semiconductor laser 52.

[0137] 10, the detection unit 96 includes a detection resistor 963. The detection resistor 963 is connected in series with the semiconductor laser 52. The detection unit 96 detects the current flowing through the detection resistor 963 as the detection result (physical quantity).

[0138] The processing unit 94 controls the magnitude of the DC voltage Vdc based on the detection result of the detection unit 96 (the current flowing through the semiconductor laser 52).

[0139] When the temperature of the semiconductor laser 52 increases, the light emission amount of the semiconductor laser 52 decreases. In the laser driving device 9, the light emission circuit 95 performs feedback control to maintain the light emission amount of the semiconductor laser 52, and therefore the current flowing through the semiconductor laser 52 increases. Therefore, when the temperature of the semiconductor laser 52 increases, the physical quantity detected by the detection unit 96 increases. In this case, the processing unit 94 controls the reference value generation unit 93 to reduce the magnitude of the DC voltage Vdc.

[0140] Furthermore, when the temperature of the semiconductor laser 52 decreases, the light emission amount of the semiconductor laser 52 increases. In the laser driving device 9, the light emission circuit 95 performs feedback control to maintain the light emission amount of the semiconductor laser 52, and therefore the current flowing through the semiconductor laser 52 decreases. Therefore, when the temperature of the semiconductor laser 52 increases, the physical quantity detected by the detection unit 96 decreases. In this case, the processing unit 94 controls the reference value generation unit 93 to increase the magnitude of the DC voltage Vdc.

[0141] In the laser driving device 9 of this modification, the processing unit 94 also controls the magnitude of the DC voltage Vdc based on the detection result of the detection unit 96, thereby making it possible to adjust the magnitude of the DC voltage Vdc to the minimum level required for the semiconductor laser 52 to emit the laser light L0. This makes it possible to suppress excess power consumption and reduce power consumption.

[0142] (3.3) Variation 3 The laser driving device 9 of this modified example will be described with reference to Fig. 11. The laser driving device 9 of this modified example differs from the laser driving device 9 of the above embodiment in the configuration of the detection unit 96. In the laser driving device 9 of this modified example, the description of the same configuration as the laser driving device 9 of the above embodiment may be omitted as appropriate.

[0143] As shown in FIG. 11, in the laser driving device 9 of this modified example, the detection unit 96 detects the temperature of the semiconductor laser 52.

[0144] 11, the detection unit 96 includes a temperature sensor 969. The temperature sensor 969 is disposed in the vicinity of the semiconductor laser 52, and detects the temperature of the semiconductor laser 52 as a detection result (physical quantity).

[0145] The processing unit 94 controls the magnitude of the DC voltage Vdc based on the detection result of the detection unit 96 (the temperature of the semiconductor laser 52).

[0146] When the temperature of the semiconductor laser 52, i.e., the physical quantity detected by the detection unit 96, increases, the processing unit 94 controls the reference value generation unit 93 to decrease the magnitude of the DC voltage Vdc. Furthermore, when the temperature of the semiconductor laser 52, i.e., the physical quantity detected by the detection unit 96, decreases, the processing unit 94 controls the reference value generation unit 93 to increase the magnitude of the DC voltage Vdc.

[0147] In the laser driving device 9 of this modification, the processing unit 94 also controls the magnitude of the DC voltage Vdc based on the detection result of the detection unit 96, thereby making it possible to adjust the magnitude of the DC voltage Vdc to the minimum level required for the semiconductor laser 52 to emit the laser light L0. This makes it possible to suppress excess power consumption and reduce power consumption.

[0148] The detection unit 96 may detect the temperature of the transistor 951 instead of or in addition to the temperature of the semiconductor laser 52. Because a common current flows through the semiconductor laser 52 and the transistor 951, the heat generation state of the transistor 951 can be said to indicate the heat generation state of the semiconductor laser 52. Therefore, by detecting the temperature of the transistor 951, the temperature state of the semiconductor laser 52 can be indirectly grasped. The processing unit 94 may control the magnitude of the DC voltage Vdc based on the detected temperature of the transistor 951.

[0149] (4) Aspects As is clear from the above-described embodiments and modifications, the present specification discloses the following aspects.

[0150] The laser driving device (9) of the first aspect includes a voltage conversion unit (92), a transistor (951), a detection unit (96), and a processing unit (94). The voltage conversion unit (92) boosts an input voltage (Vin) to a DC voltage (Vdc) higher than the input voltage (Vin) and outputs the DC voltage (Vdc) to a semiconductor laser (52). The transistor (951) is connected to the semiconductor laser (52) and adjusts the magnitude of the current flowing through the semiconductor laser (52). The detection unit (96) detects the voltage across the transistor (951). The processing unit (94) controls the magnitude of the DC voltage (Vdc) based on the detection result of the detection unit (96).

[0151] According to this aspect, it is possible to reduce power consumption.

[0152] The laser driving device (9) of the second aspect includes a voltage conversion unit (92), a detection unit (96), and a processing unit (94). The voltage conversion unit (92) boosts an input voltage (Vin) to a DC voltage (Vdc) higher than the input voltage (Vin) and outputs the DC voltage (Vdc) to the semiconductor laser (52). The detection unit (96) detects the voltage across the terminals of the semiconductor laser (52). The processing unit (94) controls the magnitude of the DC voltage (Vdc) based on the detection result of the detection unit (96).

[0153] According to this aspect, it is possible to reduce power consumption.

[0154] The laser driving device (9) of the third aspect includes a voltage conversion unit (92), a detection unit (96), and a processing unit (94). The voltage conversion unit (92) boosts an input voltage (Vin) to a DC voltage (Vdc) higher than the input voltage (Vin) and outputs the DC voltage (Vdc) to the semiconductor laser (52). The detection unit (96) detects a current flowing through the semiconductor laser (52). The processing unit (94) controls the magnitude of the DC voltage (Vdc) based on the detection result of the detection unit (96).

[0155] According to this aspect, it is possible to reduce power consumption.

[0156] A laser driving device (9) of a fourth aspect includes a voltage conversion unit (92), a transistor (951), a detection unit (96), and a processing unit (94). The voltage conversion unit (92) boosts an input voltage (Vin) to a DC voltage (Vdc) higher than the input voltage (Vin) and outputs the DC voltage (Vdc) to a semiconductor laser (52). The transistor (951) is connected to the semiconductor laser (52) and adjusts the magnitude of a current flowing through the semiconductor laser (52). The detection unit (96) detects the temperature of the semiconductor laser (52) or the transistor (951). The processing unit (94) controls the magnitude of the DC voltage (Vdc) based on the detection result of the detection unit (96).

[0157] According to this aspect, it is possible to reduce power consumption.

[0158] In the laser driving device (9) of the fifth aspect, in the first or fourth aspect, the semiconductor laser (52) is housed in the first housing (4). The transistor (951) is housed in a second housing (36) separate from the first housing (4).

[0159] According to this embodiment, it is possible to suppress a rise in temperature of the semiconductor laser 52 due to heat generated by the transistor 951, and to suppress a decrease in the light emission efficiency of the semiconductor laser 52 and a shortened lifespan.

[0160] The laser driving device (9) of the sixth aspect is any one of the first, fourth, and fifth aspects and includes a light-emitting circuit (95) including a transistor (951). The light-emitting circuit (95) further includes a light-receiving element (953) and a current control circuit (959). The light-receiving element (953) receives light from the semiconductor laser (52). The current control circuit (959) is connected to a control electrode of the transistor (951). The current control circuit (959) controls a current flowing through the control electrode in accordance with the amount of light received by the light-receiving element (953) so that the amount of light received by the light-receiving element (953) converges to a predetermined value.

[0161] According to this embodiment, it is possible to perform feedback control so that the light emission amount of the semiconductor laser (52) is constant.

[0162] In the laser driving device (9) of the seventh aspect, in any one of the first to sixth aspects, the processing unit (94) controls the magnitude of the DC voltage (Vdc) so that the magnitude of the DC voltage (Vdc) matches one of a plurality of preset target voltage values.

[0163] According to this aspect, it is possible to simplify the circuit configuration.

[0164] In the laser driving device (9) of an eighth aspect, in any one of the first to seventh aspects, the detection result of the detection unit (96) includes a physical quantity detected by the detection unit (96). The processing unit (94) decreases the magnitude of the DC voltage (Vdc) when the physical quantity increases and exceeds a first threshold, and increases the magnitude of the DC voltage (Vdc) when the physical quantity decreases and becomes equal to or smaller than a second threshold. The first threshold is greater than the second threshold.

[0165] According to this aspect, it is possible to suppress the occurrence of so-called vibrations.

[0166] In a laser driving device (9) of a ninth aspect, in any one of the first to eighth aspects, the voltage conversion unit (92) includes a signal input terminal (926), a voltage conversion circuit (920), and a switching control unit (925). A reference signal (Sin) indicating a reference value proportional to the magnitude of a DC voltage (Vdc) is input to the signal input terminal (926). The voltage conversion circuit (920) includes a switching element (923) and converts the input voltage (Vin) into a DC voltage (Vdc). The switching control unit (925) controls the duty of the switching element (923) so that the reference value coincides with a predetermined specified value. The processing unit (94) changes the reference value to change the magnitude of the DC voltage (Vdc).

[0167] According to this aspect, it is possible to change the magnitude of the DC voltage (Vdc) generated by the voltage conversion unit (92) by changing the reference value input to the switching control unit (925) without changing the processing of the switching control unit (925).

[0168] The laser marking device (1) of the tenth aspect includes the laser driving device (9) of any one of the first to ninth aspects, and an optical system (53) that converts the light emitted from the semiconductor laser (52) into linear light.

[0169] According to this aspect, it is possible to reduce power consumption. [Explanation of symbols]

[0170] 1 Laser level 36 Second cabinet 4. First cabinet 52 Semiconductor laser 53 Optical system 9 Laser driver 92 Voltage conversion unit 920 Voltage conversion circuit 923 Switching Elements 925 Switching control section 926 Signal input terminal 94 Processing section 95 Light-emitting circuit 951 Transistor (first transistor) 953 Photodetector 959 Current Control Circuit 96 Detector Sin reference signal Vin Input voltage Vdc DC voltage

Claims

1. a voltage conversion unit that boosts an input voltage to a DC voltage higher than the input voltage and outputs the DC voltage to a semiconductor laser; a transistor connected to the semiconductor laser and adjusting the magnitude of a current flowing through the semiconductor laser; a detection unit that detects a voltage between the terminals of the transistor; a processing unit that controls the magnitude of the DC voltage based on the detection result of the detection unit; Equipped with the processing unit controls the magnitude of the DC voltage so that the magnitude of the DC voltage matches one of a plurality of preset target voltage values; The processing unit When the voltage between the terminals increases and exceeds a first threshold, the magnitude of the DC voltage is reduced; increasing the magnitude of the DC voltage when the inter-terminal voltage decreases to a second threshold value or less; The first threshold is greater than the second threshold. Laser driver.

2. a voltage conversion unit that boosts an input voltage to a DC voltage higher than the input voltage and outputs the DC voltage to a semiconductor laser; a detection unit for detecting a voltage between terminals of the semiconductor laser; a processing unit that controls the magnitude of the DC voltage based on the detection result of the detection unit; Equipped with the processing unit controls the magnitude of the DC voltage so that the magnitude of the DC voltage matches one of a plurality of preset target voltage values; The processing unit When the voltage between the terminals increases and exceeds a first threshold, the magnitude of the DC voltage is reduced; increasing the magnitude of the DC voltage when the inter-terminal voltage decreases to a second threshold value or less; The first threshold is greater than the second threshold. Laser driver.

3. a voltage conversion unit that boosts an input voltage to a DC voltage higher than the input voltage and outputs the DC voltage to a semiconductor laser; a detection unit that detects a current flowing through the semiconductor laser; a processing unit that controls the magnitude of the DC voltage based on the detection result of the detection unit; Equipped with the processing unit controls the magnitude of the DC voltage so that the magnitude of the DC voltage matches one of a plurality of preset target voltage values; The processing unit When the current increases and exceeds a first threshold, the magnitude of the DC voltage is decreased; increasing the magnitude of the DC voltage when the current decreases to a second threshold value or less; The first threshold is greater than the second threshold. Laser driver.

4. a voltage conversion unit that boosts an input voltage to a DC voltage higher than the input voltage and outputs the DC voltage to a semiconductor laser; a transistor connected to the semiconductor laser and adjusting the magnitude of a current flowing through the semiconductor laser; a detection unit that detects the temperature of the semiconductor laser or the transistor; a processing unit that controls the magnitude of the DC voltage based on the detection result of the detection unit; Equipped with the processing unit controls the magnitude of the DC voltage so that the magnitude of the DC voltage matches one of a plurality of preset target voltage values; The processing unit decreasing the magnitude of the DC voltage when the temperature increases above a first threshold; increasing the magnitude of the DC voltage when the temperature decreases to a value equal to or less than a second threshold; The first threshold is greater than the second threshold. Laser driver.

5. the semiconductor laser is housed in a first housing; The transistor is housed in a second housing separate from the first housing.

5. The laser driving device according to claim 1.

6. a light-emitting circuit including the transistor, The light emitting circuit includes: a light receiving element that receives light from the semiconductor laser; a current control circuit connected to a control electrode of the transistor, the current control circuit controlling the current flowing through the control electrode in accordance with the amount of light received by the light receiving element so that the amount of light received by the light receiving element converges to a predetermined value; Further comprising:

5. The laser driving device according to claim 1.

7. further comprising a transistor connected to the semiconductor laser and adjusting the magnitude of a current flowing through the semiconductor laser; the semiconductor laser is housed in a first housing; The transistor is housed in a second housing separate from the first housing.

4. The laser driving device according to claim 2 or 3.

8. The voltage conversion unit a signal input terminal to which a reference signal indicating a reference value proportional to the magnitude of the DC voltage is input; a voltage conversion circuit including a switching element for converting the input voltage into the DC voltage; a switching control unit that controls a duty of the switching element so that the reference value coincides with a predetermined specified value; Equipped with The processing unit changes the reference value to change the magnitude of the DC voltage. The laser driving device according to any one of claims 1 to 4.

9. A laser driving device according to any one of claims 1 to 4; an optical system that converts the light emitted from the semiconductor laser into linear light; Equipped with Laser level.

10. A laser driving device according to claim 5; an optical system that converts the light emitted from the semiconductor laser into linear light; Equipped with Laser level.

11. A laser driving device according to claim 6; an optical system that converts the light emitted from the semiconductor laser into linear light; Equipped with Laser level.

12. A laser driving device according to claim 7; an optical system that converts the light emitted from the semiconductor laser into linear light; Equipped with Laser level.

13. A laser driving device according to claim 8; an optical system that converts the light emitted from the semiconductor laser into linear light; Equipped with Laser level.

Images