JP2016195041A - Light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light source device capable of detecting a site at which ground fault occurs.SOLUTION: A light source device 1 includes a light source unit 11 having at least one light emitting element L, a shunt resistor 12 provided on a high potential side of the light source section 11, a shunt resistor 22 provided on a low potential side of the light source unit 11, and a ground fault detector 14 for detecting a site having a ground fault occurring therein based on a voltage drop occurring at the shunt resistor 12 and a voltage drop occurring at the shunt resistor 22.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a light source device.

  Light emitting elements such as a laser diode (LD) and a light emitting diode (LED) have features such as small size, low power consumption, and long life, and thus are widely used in various applications. For example, laser diodes are used as fiber laser excitation light sources, and light-emitting diodes are used in various lighting devices such as vehicle headlights. Such light-emitting elements are used alone or in a plurality connected in series according to the required light quantity.

  In the light source device including the above light emitting element, when a ground fault occurs, the light emitting element is always turned on, and a situation in which unnecessary light continues to be output from the light source device occurs. In order to prevent such a situation, the light source device is often provided with a ground fault detection circuit for detecting a ground fault. For example, Patent Document 1 below discloses a ground fault detection circuit that detects a ground fault by providing a shunt resistor on the low potential side of an LED.

JP 2014-154448 A

  By the way, although the ground fault detection circuit disclosed by said patent document 1 can detect the presence or absence of generation | occurrence | production of a ground fault, it cannot detect the location where the ground fault occurred. In a light source device that requires high output (for example, a fiber laser excitation light source), the number of light emitting elements provided in the light source device tends to increase. For example, when taking a countermeasure against a ground fault, It will be important in the future to detect the location where the entanglement occurred.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a light source device capable of detecting a location where a ground fault has occurred.

In order to solve the above problems, a light source device of the present invention is provided on a high potential side of the light source unit in the light source unit (1, 2) including the light source unit (11) having at least one light emitting element (L). Based on the first resistance (12) provided, the second resistance (22) provided on the low potential side of the light source unit, and the voltage drop caused by the first resistance and the voltage drop caused by the second resistance. And a ground fault detector (14) for detecting a location where a ground fault has occurred.
In the light source device of the present invention, the ground fault detection unit may reduce a voltage drop generated in the first resistor from a power supply voltage applied to the light source unit when a voltage drop generated in the second resistor is zero. The voltage obtained by subtracting is divided by the voltage drop generated in each of the light emitting elements provided in the light source unit to detect a location where a ground fault has occurred.
In addition, the light source device of the present invention includes a power control unit (15) that stops power supply to the light source unit when a ground fault is detected by the ground fault detection unit.
The light source device of the present invention includes a plurality of circuits (C1 to C3) connected in parallel to each other and having the first resistor, the light source unit, and the second resistor. It is characterized by detecting a location where a ground fault has occurred in each circuit.
In addition, the light source device of the present invention includes a drive unit (13) provided on the low potential side of the light source unit and including the second resistor and a drive element (21) for driving the light source unit. Yes.

  According to the present invention, the first resistor is provided on the high potential side of the light source unit and the second resistor is provided on the low potential side of the light source unit, and based on the voltage drop caused by the first resistor and the voltage drop caused by the second resistor. The location where a ground fault has occurred is detected. For this reason, not only can it be determined whether or not a ground fault has occurred, but it is also possible to detect the location where the ground fault has occurred.

It is a block diagram which shows the principal part structure of the light source device by 1st Embodiment of this invention. It is a figure which shows the example of a state with which the ground fault occurred in 1st Embodiment of this invention. It is a figure which shows an example of the current-voltage characteristic of the light emitting element with which the light source device by 1st Embodiment of this invention is provided. It is a block diagram which shows the principal part structure of the light source device by 2nd Embodiment of this invention. It is a block diagram which shows the principal part structure of a fiber laser apparatus provided with the light source device by embodiment of this invention.

  Hereinafter, a light source device according to an embodiment of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is a block diagram showing the main configuration of the light source device according to the first embodiment of the present invention. As shown in FIG. 1, the light source device 1 of the present embodiment includes a light source unit 11, a shunt resistor 12 (first resistor), a drive unit 13, a ground fault detection unit 14, and a power supply control unit 15. Outputs light of a wavelength (for example, visible light, infrared light, or ultraviolet light). Further, the light source device 1 of the present embodiment can detect a ground fault occurring in the light source unit 11 and the like. The light source device 1 operates with electric power supplied from the power supply unit PS through the power supply line PL.

  The light source unit 11 includes a plurality of light emitting elements L connected in series. The light emitting element L is a solid light source such as an LD (Laser Diode) or an LED (Light Emitting Diode). The number of the light emitting elements L is set according to the required light quantity. In the present embodiment, it is assumed that 20 light emitting elements L are provided in the light source unit 11 for easy understanding. The light source unit 11 may include only one light emitting element L.

  The shunt resistor 12 is a resistor provided on the high potential side of the light source unit 11 and is provided for detecting a current flowing through the light source unit 11 (more precisely, a current flowing into the light source unit 11 from the power line PL). Specifically, the shunt resistor 12 has one end connected to the light source unit 11 and the other end connected to the power supply line PL. A detection signal (a signal indicating a current detection result) D1 of the shunt resistor 12 is output to the ground fault detection unit 14. The detection signal D1 is also a signal indicating a voltage drop of the shunt resistor 12 generated according to the current flowing through the shunt resistor 12.

  Here, if the resistance value of the shunt resistor 12 is large, power loss increases (heat generation increases). Therefore, it is desirable that the resistance value of the shunt resistor 12 is small. However, if the resistance value of the shunt resistor 12 is too small, the voltage drop generated in the shunt resistor 12 becomes small and detection errors are likely to occur. For this reason, the resistance value of the shunt resistor 12 is set in consideration of power loss and detection error. For example, the resistance value of the shunt resistor 12 is set to about 0.1 [Ω].

  The drive unit 13 includes a field effect transistor (FET) 21 (drive element), a shunt resistor 22 (second resistor), and an FET drive circuit 23, and is provided on the low potential side of the light source unit 11. The current flowing through the light source unit 11 is controlled. Specifically, the drive unit 13 is provided between the light source unit 11 and the ground G, and controls so that a constant current flows through the light source unit 11.

  The FET 21 is a current control element that is provided between the light source unit 11 and the shunt resistor 22 and is driven by a drive signal DS output from the FET drive circuit 23. The FET 21 has, for example, a drain terminal connected to the light source unit 11, a source terminal connected to the shunt resistor 22, and a gate terminal connected to the FET drive circuit 23. A bipolar transistor can be used in place of the FET 21.

  The shunt resistor 22 is a resistor provided on the low potential side of the light source unit 11 and is provided for detecting a current flowing through the light source unit 11 (more precisely, a current flowing out from the light source unit 11 to the ground G). Specifically, the shunt resistor 22 has one end connected to the FET 21 and the other end connected to the ground G. The detection signal (signal indicating the current detection result) D2 of the shunt resistor 22 is output to the ground fault detection unit 14 and the FET drive circuit 23. The detection signal D2 is also a signal indicating a voltage drop of the shunt resistor 22 generated according to the current flowing through the shunt resistor 22.

  Here, like the shunt resistor 12, the resistance value of the shunt resistor 22 is set in consideration of power loss and detection error. The resistance value of the shunt resistor 22 may be the same as or different from the resistance value of the shunt resistor 12. For example, the resistance value of the shunt resistor 22 is set to about 0.1 [Ω], which is the same as the resistance value of the shunt resistor 12.

  The FET drive circuit 23 drives the FET 21 based on the detection signal D2 output from the shunt resistor 22. Specifically, the FET drive circuit 23 generates the drive signal DS that makes the current flowing through the light source unit 11 constant based on the detection signal D2, and drives the FET 21. As a driving method of the FET 21 by the FET driving circuit 23, for example, a driving method in which the current flowing in the FET 21 is controlled in an analog manner to be constant is used. The driving method of the FET 21 by the FET driving circuit 23 is not limited to the above driving method, and any driving method can be used.

  When the ground fault detector 14 determines whether or not a ground fault has occurred based on the detection signal D1 output from the shunt resistor 12 and the detection signal D2 output from the shunt resistor 22 and determines that a ground fault has occurred. Detects where a ground fault has occurred. For example, when the detection signal D2 output from the shunt resistor 12 is non-zero even though the detection signal D2 output from the shunt resistor 22 is zero, the ground fault detection unit 14 performs the shunt resistor 22. Since no current is flowing through it and it can be determined that a current has flowed to the ground G between the shunt resistor 12 and the shunt resistor 22, it can be determined that a ground fault has occurred.

  The ground fault detection unit 14 stores resistance values of the shunt resistors 12 and 22 in advance, and the detection signals D1 and D2 are signals indicating current detection results. Therefore, the ground fault detection unit 14 obtains a voltage drop generated in the shunt resistor 12 by multiplying the detection signal D1 and the resistance value of the shunt resistor 12, and multiplies the detection signal D2 and the resistance value of the shunt resistor 22. As a result, a voltage drop generated in the shunt resistor 22 is obtained. For this reason, the ground fault detection unit 14 may determine whether or not a ground fault has occurred based on the voltage drop caused by the shunt resistor 12 and the voltage drop caused by the shunt resistor 22.

  The ground fault detection unit 14 detects a location where a ground fault has occurred based on the voltage drop caused by the shunt resistor 12 and the voltage drop caused by the shunt resistor 22. Specifically, the ground fault detection unit 14 detects the shunt from the power supply voltage applied to the light source unit 11 when the voltage drop generated by the shunt resistor 22 is zero and the voltage drop generated by the shunt resistor 12 is non-zero. The voltage obtained by subtracting the voltage drop generated by the resistor 12 is divided by the voltage drop generated by each light emitting element L provided in the light source unit 11 to detect the location where the ground fault has occurred.

  FIG. 2 is a diagram illustrating an example of a state in which a ground fault has occurred in the first embodiment of the present invention. In FIG. 2, the same blocks as those shown in FIG. In the example illustrated in FIG. 2, among the 20 light emitting elements L provided in the light source unit 11, the connection point Z between the second light emitting element L and the third light emitting element L from the high potential side. It is said that a ground fault has occurred. When such a ground fault occurs, as shown in FIG. 2, a current flows through a path P indicated by a white arrow in the figure. That is, a current flows through the two light emitting elements L on the higher potential side than the shunt resistor 12 and the connection location Z, but no current flows through the 18 light emitting elements L on the lower potential side than the connection location Z.

  FIG. 3 is a diagram illustrating an example of current-voltage characteristics of the light-emitting elements included in the light source device according to the first embodiment of the present invention. Note that FIG. 3 shows current-voltage characteristics of an LD, which is a kind of light-emitting element L, in which the horizontal axis represents current and the vertical axis represents voltage. As shown in FIG. 3, the light emitting element L has a characteristic that the voltage (voltage drop) hardly changes even if the current changes if the flowing current is larger than a certain value (current It in FIG. 2). For this reason, the reference value V0 of the voltage drop of the light emitting element L can be set as shown in FIG.

As shown in FIG. 2, the output voltage (power supply voltage) of the power supply unit PS is Vdd, the voltage drop generated by the shunt resistor 12 is V1, and the voltage drop generated by the light source unit 11 is V2. When the ground fault shown in FIG. 2 occurs, the power supply voltage Vdd is divided by the shunt resistor 12 and the light source unit 11. For this reason, the voltage drop V2 which arises in the light source part 11 is calculated | required by the following (1) Formula.
V2 = Vdd−V1 (1)

As described with reference to FIG. 3, the voltage drop (voltage drop) of the light emitting element L provided in the light source unit 11 hardly changes even when the current changes. Can be regarded as a reference value V0. For this reason, the number Q of the light emitting elements L through which the current flows among the 20 light emitting elements L provided in the light source unit 11 can be obtained from the following equation (2).
Q = V2 / V0 (2)

  Thus, the ground fault detection unit 14 obtains the voltage drop V2 generated in the light source unit 11 by subtracting the voltage drop V1 generated in the shunt resistor 12 from the power supply voltage Vdd (the above formula (1)). Then, the ground fault detection unit 14 performs a calculation (the above formula (2)) by dividing the obtained voltage drop V2 by the voltage drop (reference value V0) generated in each light emitting element L provided in the light source unit 11. Thus, the number Q of the light emitting elements L up to the ground fault location is obtained. In this way, the ground fault detection unit 14 detects a location where a ground fault has occurred.

  The power supply control unit 15 performs control to stop the power supply to the light source unit 11 when the ground fault detection unit 14 determines that a ground fault has occurred (when a ground fault is detected). Specifically, when the ground fault detection unit 14 determines that a ground fault has occurred, the power control unit 15 outputs a power supply stop signal S1 to the power source unit PS, thereby Stop the power supply. The reason why such control is performed is to prevent a situation in which the light emitting element L is constantly lit due to a ground fault and unnecessary light continues to be output from the light source device 1.

  Next, operation | movement of the light source device 1 in the said structure is demonstrated easily. When the driving of the FET 21 by the FET driving circuit 23 is started, the current supplied from the power supply unit PS to the power supply line PL flows through the shunt resistor 12, the light source unit 11, the FET 21, and the shunt resistor 22 in order and then to the ground G. Flows in. In the drive unit 13, the FET 21 is driven by the FET drive circuit 23 so that the current flowing through the light source unit 11 has a desired value.

  In a normal state in which no ground fault has occurred, the current supplied from the power supply unit PS to the power supply line PL flows through the shunt resistor 12, the light source unit 11, the FET 21, and the shunt resistor 22 in order. For this reason, the detection signal D1 (or voltage drop of the shunt resistor 12) output from the shunt resistor 12 and the detection signal D2 (or voltage drop of the shunt resistor 22) output from the shunt resistor 22 do not become zero. . For this reason, the ground fault detection unit 14 determines that no ground fault has occurred.

  On the other hand, in an abnormal state in which a ground fault occurs, the current supplied from the power supply unit PS to the power supply line PL flows to the light emitting elements L of the shunt resistor 12 and the light source unit 11, but the FET 21 and the shunt resistor 22. Therefore, the detection signal D1 output from the shunt resistor 12 is non-zero even though the detection signal D2 output from the shunt resistor 22 is zero. For this reason, the ground fault detection unit 14 determines that a ground fault has occurred.

  When it is determined that a ground fault has occurred, the ground fault detection unit 14 performs the calculations shown in the above-described equations (1) and (2), and obtains the number Q of light emitting elements L up to the ground fault location. For example, the power supply voltage Vdd is 40 [V], the current flowing through the light source unit 11 (normal current) is 10 [A], and the voltage drop reference value V0 of the light emitting element L is 1.7 [V]. Consider a case. In this case, if the voltage drop V1 generated in the shunt resistor 12 is 34.9 [V] and the voltage drop generated in the shunt resistor 22 is 0 [V], the voltage drop V2 generated in the light source unit 11 is as described above. From the formula (1), V2 = 5.1 [V] (= 40 [V] -4.9 [V]) is obtained. Further, the number Q of the light emitting elements L to the ground fault location is obtained as 3 (= 5.1 [V] /1.7 [V]) from the above-described equation (2). Therefore, in the above case, it is detected that a ground fault has occurred between the third light emitting element L and the fourth light emitting element L from the high potential side.

  In this way, the ground fault detection unit 14 detects a location where a ground fault has occurred. When it is determined that a ground fault has occurred, a signal indicating that a ground fault has occurred is output from the ground fault detection unit 14 to the power supply control unit 15. Then, a power supply stop signal S1 is output from the power supply control unit 15 to the power supply unit PS, and power supply from the power supply unit PS to the power supply line PL is stopped. Thereby, the power supply to the light source unit 11 is stopped, and a situation where unnecessary light continues to be output from the light source device 1 is prevented.

  As described above, in the present embodiment, the shunt resistor 12 is provided on the high potential side of the light source unit 11, and the shunt resistor 22 is provided on the low potential side of the light source unit 11, and the shunt resistors 12 and 22 are based on the voltage drop. The ground fault detection unit 14 detects the location where the ground fault has occurred. For this reason, it is possible not only to determine whether or not a ground fault has occurred, but also to detect a location where a ground fault has occurred.

[Second Embodiment]
FIG. 4 is a block diagram showing a main configuration of a light source device according to the second embodiment of the present invention. In FIG. 4, blocks corresponding to the blocks shown in FIGS. As illustrated in FIG. 4, the light source device 2 of the present embodiment includes a light source unit 11, a shunt resistor 12, and a drive unit 13, and includes a plurality of circuits C <b> 1 to C <b> 1 connected in parallel between the power supply line PL and the ground G. C3 is provided. Such a light source device 2 increases the amount of light to increase the output. The light source device 2 shown in FIG. 4 includes three circuits C1 to C3 between the power supply line PL and the ground G. However, the number of circuits provided between the power supply line PL and the ground G is necessary. Is set according to the amount of light.

  From the shunt resistor 12 provided in each of the circuits C1 to C3 illustrated in FIG. 4, a detection signal D1 that is a signal indicating a detection result of the current flowing in each of the circuits C1 to C3 is output. Further, a current flowing in each of the circuits C1 to C3 is detected from a shunt resistor 22 (not shown in FIG. 4) provided in the drive unit 13 provided in each of the circuits C1 to C3 shown in FIG. A detection signal D2 that is a signal indicating the result is output. These detection signals D1 and D2 are input to the ground fault detection unit 14.

  The ground fault detection unit 14 individually determines whether or not a ground fault has occurred for each of the circuits C1 to C3 using the detection signals D1 and D2. In addition, when it is determined that a ground fault has occurred, the ground fault detection unit 14 detects a location where a ground fault has occurred in the circuit determined to have a ground fault among the circuits C1 to C3. For each of the circuits C1 to C3, the method for determining whether or not a ground fault has occurred and the method for detecting the location where the ground fault has occurred are the same as in the first embodiment.

  When the ground fault detection unit 14 determines that a ground fault has occurred in any of the circuits C1 to C3, a signal indicating that a ground fault has occurred is output from the ground fault detection unit 14 to the power supply control unit 15. The Thereby, the power supply stop signal S1 is output from the power supply control unit 15 to the power supply unit PS, and the power supply from the power supply unit PS to the power supply line PL is stopped. As described above, in this embodiment, when a ground fault occurs in any of the circuits C1 to C3 provided in the light source device 2, power supply to all the light source units 11 provided in the circuits C1 to C3 is stopped. The

  As described above, in the present embodiment, the shunt resistor 12 is provided on the high potential side of each of the plurality of light source units 11 and the shunt resistor 22 is provided on the low potential side of each of the plurality of light source units 11. The ground fault detection unit 14 detects a location where a ground fault has occurred based on the voltage drop at the shunt resistors 12 and 22. For this reason, it is possible not only to determine which light source unit 11 has caused a ground fault, but also to detect a location where a ground fault has occurred in the light source unit 11 where it is determined that a ground fault has occurred.

[Fiber laser equipment]
FIG. 5 is a block diagram showing a main configuration of a fiber laser device including the light source device according to the embodiment of the present invention. As shown in FIG. 5, the fiber laser apparatus FL includes an optical fiber F1 functioning as an amplification medium, an optical fiber F2 functioning as a transmission medium, a light source device 31, an optical power monitor device 32, and a control device 33, and is controlled. Under the control of the device 33, the output light L1 is output from the output end X of the optical fiber F2.

  The optical fiber F1 functioning as an amplifying medium is a single clad fiber including a core to which an active element is added and a clad surrounding the core. The optical fiber F1 amplifies light propagating through the core of the optical fiber F1 by the active element excited by the excitation light supplied from the light source device 31. In this optical fiber F1, fiber Bragg gratings G1 and G2 in which the refractive index of the core is periodically changed are formed. For this reason, the light propagating through the core of the optical fiber F1 is amplified while being repeatedly reflected by these two fiber Bragg gratings G1 and G2.

  The optical fiber F2 functioning as a transmission medium is a single clad fiber including a core and a clad surrounding the core. In addition, the active element is not added to the core of the optical fiber F2 unlike the core of the optical fiber F1. One end of the optical fiber F <b> 2 is an output end X of the output light L <b> 1, and the other end is fusion-connected to the optical fiber F <b> 1 in the optical power monitor device 32.

  The light source device 31 is the light source device 1 according to the first embodiment shown in FIG. 1 or the light source device 2 according to the second embodiment shown in FIG. 4, and pumps the optical fiber F1 under the control of the control device 33. Supply. The optical power monitoring device 32 includes the power of the output light L1 output from the output end X of the optical fiber F2 and the reflected light L2 input through the output end X (for example, on the processing surface of the workpiece during processing of the workpiece). Of the generated reflected light, the power of the reflected light input via the output terminal X is monitored.

  The control device 33 refers to the power of the output light L1 and the reflected light L2 monitored by the optical power monitor device 32, and controls the light source device 31 so that the power of the output light L1 output from the output terminal X is constant. Control. Further, the control device 33 emits light from the light source device 31 in order to protect the fiber laser device FL when the power of the reflected light L2 monitored by the optical power monitoring device 32 exceeds a predetermined threshold value. Control to stop.

  In such a fiber laser device FL, the light source device 31 determines whether or not a ground fault has occurred using the detection signals D1 and D2 output from the shunt resistors 12 and 22 (see FIGS. 1 and 4). When it is determined that a ground fault has occurred, the location where the ground fault has occurred is detected, and the power supply to the light source unit 11 provided in the light source device 31 is stopped, and the light emission of the light source device 31 is stopped. The

  As mentioned above, although embodiment of this invention was described, this invention is not restrict | limited to the said embodiment, It can change freely within the scope of the present invention. For example, in the above-described embodiment, the example in which the shunt resistor 22 is provided in the drive unit 13 has been described. However, the shunt resistor 22 may be provided between the light source unit 11 and the ground G. It is not necessary to be provided in the drive unit 13.

  The light source unit 11 may be mounted in a form in which a plurality of light emitting modules (single chip light emitting modules) each including only one light emitting element L are connected in series. A form including a multi-chip light emitting module housed in a package may be employed. That is, the mounting form of the light source unit 11 is not limited to a specific form and can be an arbitrary form. Further, the light source devices 1 and 2 can be applied to various illumination devices other than the fiber laser device FL.

DESCRIPTION OF SYMBOLS 1, 2 ... Light source device, 11 ... Light source part, 12 ... Shunt resistance, 13 ... Drive part, 14 ... Ground fault detection part, 15 ... Power supply control part, 21 ... FET, 22 ... Shunt resistance, C1-C3 ... Circuit, L ... Light emitting element

Claims (5)

In a light source device including a light source unit having at least one light emitting element,
A first resistor provided on the high potential side of the light source unit;
A second resistor provided on the low potential side of the light source unit;
A light source device comprising: a ground fault detection unit that detects a location where a ground fault has occurred based on a voltage drop caused by the first resistor and a voltage drop caused by the second resistor.   When the voltage drop generated by the second resistor is zero, the ground fault detection unit obtains a voltage obtained by subtracting the voltage drop generated by the first resistor from a power supply voltage applied to the light source unit. The light source device according to claim 1, wherein a location where a ground fault occurs is detected by performing an operation of dividing by a voltage drop generated in each of the light emitting elements provided in the section.   3. The light source device according to claim 1, further comprising: a power supply control unit configured to stop power supply to the light source unit when a ground fault is detected by the ground fault detection unit. A plurality of circuits connected in parallel to each other and having the first resistor, the light source unit, and the second resistor;
The light source device according to any one of claims 1 to 3, wherein the ground fault detection unit detects a location where a ground fault occurs in each of the circuits.   3. The light source device according to claim 1, further comprising a drive unit that is provided on a low potential side of the light source unit and includes the second resistor and a drive element that drives the light source unit.

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