JP5117524B2 - Laser diode control apparatus and laser diode control method - Google Patents

Description

  The present invention relates to a laser diode control device and a laser diode control method.

  Conventional optical fiber amplifiers, fiber lasers, and the like include a laser diode control device that controls the drive current of the pumping laser diode in order to adjust the light output level. As shown in FIG. 10, in the laser diode control device 100, a laser diode drive unit 101 for flowing a desired current to the laser diode 110, and a current monitor unit 102 for monitoring the current flowing to the laser diode 110, The alarm determination unit 103 for monitoring the current flowing through the laser diode 110 is incorporated. As shown in FIG. 11, the alarm determination unit 103 compares the current monitor value acquired from the current monitor unit 102 with a preset current threshold value, and the current monitor value exceeds the current threshold value. In the case (on the left side in FIG. 11), it is determined that there is an abnormality, and an alarm is issued to the outside. Patent Document 1 discloses a technique that has the same configuration as that shown in FIG. 10 and periodically tests the monitoring unit to prevent application of excessive drive current to the laser diode in order to prevent malfunction. It is disclosed.

Japanese Patent Laid-Open No. 05-227097

  By the way, as shown in FIG. 12, when the laser diode driver 101 is out of order, the current value output when the laser diode 110 is off exceeds the current threshold (left side of FIG. 12). An alarm is issued, but no alarm is issued when the current value does not exceed the current threshold (right side in FIG. 12). When the laser diode 110 is in an off state, the current value must be “0”, which is clearly a failure. However, such a failure has a problem in that it cannot be an alarm target.

  Therefore, a problem to be solved by the present invention is to provide a laser diode control device and a laser diode control method capable of reliably detecting a failure.

In order to solve the above-described problems, a laser diode driving device according to the present invention is a laser diode control device that controls a laser diode, and a driving unit that drives the laser diode, and a driving current is supplied to the laser diode by the driving unit. Switching means for switching between an operating state to be stopped and a stop state to stop the supply of the drive current, a detecting means for detecting the state of the laser diode, and the detecting means when the laser diode is in the operating state When the laser diode is in the stopped state, the detection result of the detecting means and the first determination threshold value are different from each other. Determining means for comparing the determination threshold value to determine the presence or absence of abnormality.
According to such a configuration, it is possible to reliably detect a failure.

According to another invention, in addition to the above invention, the detection means detects the drive current of the laser diode, and the first determination threshold is a predetermined value larger than the drive current in the operating state of the laser diode. The second determination threshold value is smaller than the first determination threshold value and is a predetermined value close to 0 or 0.
According to such a configuration, since it is determined whether there is an abnormality based on an appropriate determination threshold corresponding to the state of the laser diode, it is possible to reliably detect a failure.

According to another invention, in addition to the above-mentioned invention, the switching means outputs state information indicating its own state, and the determination means is in an abnormal state when the state information of the switching means is not normal. It is characterized by determining that it has occurred.
According to such a configuration, it is possible to detect a failure of the switching means.

According to another invention, in addition to the above invention, the determination means stops the operation of the switching means in a stopped state when it is determined that an abnormality has occurred based on the state information. To do.
According to such a configuration, when an abnormality occurs, the switching unit is stopped in a stopped state, so that it is possible to prevent the laser diode from being loaded.

According to another aspect of the invention, in addition to the above-described invention, the detection unit detects the drive current value of the laser diode, and the determination unit is configured to detect the set value of the drive current in the operating state and the detection unit. The detected actual drive current value is compared, and if they differ by a predetermined value or more, it is determined that there is an abnormality.
According to such a configuration, it is possible to determine whether or not the control is appropriately executed by comparing the set value and the detected value, and when it is not appropriate, it can be determined that an abnormality has occurred. .

According to another invention, in addition to the above invention, the detection means detects an output light intensity of the laser diode, and the first determination threshold is a predetermined value larger than an output light intensity in the operating state of the laser diode. The second determination threshold value is smaller than the first determination threshold value and is a predetermined value close to 0 or 0.
According to such a configuration, since the presence / absence of an abnormality is determined based on the light intensity, it is possible to know whether the laser diode is overloaded and to detect that the light output is being performed in the off state. Thus, it is possible to detect a failure of the driving means.

In addition to the above invention, another invention includes a cooling means for cooling the laser diode, the detection means detects the temperature of the laser diode itself or its surroundings, and the determination means is the cooling means. A first determination threshold value that is higher than the control target temperature according to the above and a second determination threshold value determined by the environmental temperature, and when the cooling means is in an operating state, the first determination threshold value and the detection means The temperature is compared, and when the vehicle is in a stopped state, the second determination threshold is compared with the temperature detected by the detection means, and the presence or absence of an abnormality is determined based on the magnitude relationship between these.
According to such a configuration, since it is possible to determine whether there is an abnormality based on the temperature of the laser diode itself or its surroundings, for example, it is possible to reliably detect the occurrence of an abnormality due to a cooling failure.

According to another invention, in addition to the above invention, the determination means selects the first determination threshold value or the second determination threshold value based on a magnitude relationship of detection results by the detection means. .
According to such a configuration, since the determination threshold value is selected based on the magnitude relationship between the detection results of the detection means, for example, a delay or the like exists between the switching operation of the switching means and the detection results of the detection means. Even if it is a case, abnormality can be detected reliably.

According to another aspect of the present invention, there is provided a laser diode control method for controlling a laser diode, the switching step of switching between an operation state for supplying a drive current to the laser diode and a stop state for stopping the supply of the drive current; A detection step of detecting a state of a diode; and when the laser diode is in the operating state, the detection result of the detection step is compared with a first determination threshold value to determine whether there is an abnormality, and the laser diode A determination step of determining the presence or absence of an abnormality by comparing the detection result of the detection step with a second determination threshold value different from the first determination threshold value in the stop state. .
According to such a method, it is possible to reliably detect a failure.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the laser diode control apparatus and laser diode control method which can detect a failure reliably.

It is a figure which shows the structural example of the laser diode control apparatus which concerns on 1st Embodiment of this invention. It is a flowchart for demonstrating operation | movement of the laser diode control apparatus shown in FIG. It is a figure for demonstrating operation | movement of the laser-diode control apparatus shown in FIG. It is a figure which shows the structural example of the laser diode control apparatus which concerns on 2nd Embodiment of this invention. It is a figure which shows the structural example of the laser diode control apparatus which concerns on 3rd Embodiment of this invention. It is a figure which shows the structural example of the laser diode control apparatus which concerns on 4th Embodiment of this invention. It is a figure which shows the structural example of the laser diode control apparatus which concerns on 5th Embodiment of this invention. It is a figure which shows the structural example of the laser diode control apparatus which concerns on 6th Embodiment of this invention. It is a figure for demonstrating operation | movement of the laser-diode control apparatus shown in FIG. It is a figure which shows the structure of the conventional laser diode control apparatus. It is a figure for demonstrating operation | movement of the conventional laser diode control apparatus shown in FIG. It is a figure for demonstrating operation | movement of the conventional laser diode control apparatus shown in FIG.

  Next, an embodiment of the present invention will be described.

(A) 1st Embodiment FIG. 1: is a figure which shows the structural example of the laser diode control apparatus which concerns on 1st Embodiment of this invention. As shown in FIG. 1, the laser diode control device 1 according to the first embodiment includes a laser operation monitoring unit 10, a laser diode driving unit 20 (corresponding to a part of “driving means” in the claims), and a current. The monitor unit 30 (corresponding to “detection means” in the claims) is a main component, and a drive current is supplied to the laser diode 110 to control it. The laser operation monitoring unit 10 corresponds to a current instruction unit 11, an ON / OFF instruction unit 12 (corresponding to a part of “switching means” in the claims), and a threshold value changing unit 13 (corresponding to a part of “judging means” in the claims) ) And an alarm determination unit 14 (corresponding to a part of “determination means” in the claims) as main components, and controls the drive current supplied to the laser diode 110 and monitors the occurrence of abnormality.

  Here, the current instruction unit 11 instructs the value of the drive current supplied to the laser diode 110 as a current instruction value according to the light intensity of the laser light to be output from the laser diode 110. The ON / OFF instruction unit 12 supplies the presence / absence (ON or OFF) of the supply of drive current to the laser diode 110 as an ON / OFF signal. The ON / OFF instruction unit 12 also supplies the same signal to the threshold value changing unit 13. Based on the ON / OFF signal supplied from the ON / OFF instruction unit 12, the threshold change unit 13 selects and outputs one of two determination thresholds described later to the alarm determination unit 14. The alarm determination unit 14 compares the drive current value (current monitor value) of the laser diode 110 detected by the current monitor unit 30 with the determination threshold value supplied from the threshold value changing unit 13, and generates an alarm based on the comparison result. Issue.

  The laser diode drive unit 20 intermittently supplies a drive current corresponding to the current instruction value supplied from the current instruction unit 11 to the laser diode 110 in response to the ON / OFF signal supplied from the ON / OFF instruction unit 12. To supply. The laser diode 110 emits laser light based on the drive current supplied from the laser diode driver 20. The current monitor unit 30 detects the drive current supplied from the laser diode driver 20 to the laser diode 110 and supplies the detected current to the alarm determination unit 14 as a current monitor value.

  Next, the operation of the first embodiment will be described. FIG. 2 is a flowchart for explaining the operation of the first embodiment shown in FIG. When the process of this flowchart is started, the following steps are executed.

  In step S10, it is determined whether or not the ON / OFF signal output from the ON / OFF instruction unit 12 indicates an ON state. If the ON state is instructed (step S10; YES), The process proceeds to step S11, and otherwise (step S10; NO), the process proceeds to step S13. Specifically, for example, the ON / OFF instructing unit 12 outputs an ON or OFF instruction at a predetermined cycle, and therefore, if ON is output, the process proceeds to step S11, and otherwise Advances to step S13.

  In step S <b> 11, the laser diode driver 20 drives the laser diode 110. Specifically, the laser diode driving unit 20 supplies a driving current corresponding to the current instruction value supplied from the current instruction unit 11 to the laser diode 110. As a result, the laser diode 110 emits laser light and enters an operating state.

  In step S12, the threshold value changing unit 13 substitutes the first determination threshold value as the determination threshold value into the variable Th. Here, the first determination threshold is set to a value larger than the drive current that normally flows in the state where the laser diode 110 is operating (see the left bar graph in FIG. 3) (see “first determination threshold” in FIG. 3). In the operating state, when a drive current exceeding the first determination threshold flows, it can be determined that the laser diode driver 20 is out of order.

  In step S <b> 13, the laser diode driver 20 stops driving the laser diode 110. Specifically, the laser diode driving unit 20 stops the current supplied to the laser diode 110 regardless of the current instruction value supplied from the current instruction unit 11. As a result, the laser diode 110 stops emitting laser light and enters a stopped state.

  In step S14, the threshold value changing unit 13 substitutes the second determination threshold value as the determination threshold value into the variable Th. Here, the second determination threshold value is set to a value that is slightly larger than the driving current (see the bar graph on the right side of FIG. 3) that flows when the laser diode 110 is stopped (“second determination threshold value” in FIG. 3). In the stop state, when a driving current exceeding the second determination threshold flows, it can be determined that the laser diode driving unit 20 has failed.

  In step S15, the current monitor value detected by the current monitor unit 30 is acquired and substituted into the variable Im. Specifically, the current monitor unit 30 detects the drive current supplied from the laser diode drive unit 20 to the laser diode 110 and supplies the detected current to the alarm determination unit 14 as a current monitor value. The alarm determination unit 14 substitutes the current monitor value supplied from the current monitor unit 30 for the variable Im.

  In step S16, the alarm determination unit 14 determines whether or not the current monitor value Im supplied from the current monitor unit 30 is smaller than the determination threshold Th set in step S12 or step S14, and determines that the current monitor value Im is small. In this case (step S16: YES), it is determined that there is no abnormality and the process returns to step S10 to repeat the same process as described above. In other cases (step S16: NO), it is determined that an abnormality has occurred and step S17 is performed. Proceed to Specifically, as shown in FIG. 3, when the laser diode 110 is in an on state (operating state), the first determination threshold value (Th) and the current monitor value (Im) are compared, and the current monitor value <If it is the first determination threshold, it is determined that there is no abnormality, and the process returns to step S10. Otherwise, it is determined that an abnormality has occurred and the process proceeds to step S17. On the other hand, when the laser diode 110 is in an off state (stopped state), the second determination threshold value and the current monitor value are compared, and when the current monitor value <the second determination threshold value, it is determined that there is no abnormality. Returning to step S10, otherwise, it is determined that an abnormality has occurred and the process proceeds to step S17.

  In step S <b> 17, the alarm determination unit 14 issues an alarm to the outside, assuming that an abnormality has occurred, and ends the process. In addition, in order to clarify the cause of the occurrence of the abnormality, it may be notified whether the abnormality has occurred in relation to the first or second determination threshold value.

  As described above, according to the first embodiment of the present invention, the first determination threshold and the second determination threshold are selected according to the driving state and the stop state of the laser diode 110, and compared with the current monitor value. Since the presence / absence of an abnormality is determined, not only when a large drive current flows to the laser diode 110 in the operating state due to a failure of the laser diode drive unit 20, but also due to a failure of the laser diode drive unit 20. Even when an unnecessary current flows to the laser diode 110 in the stopped state, it can be determined as abnormal. Thereby, it becomes possible to determine the failure of the laser diode driver 20 more accurately. In addition, the burden on the laser diode 110 can be reduced by accurately detecting the failure. As described above, as the second determination threshold value, 0 or a predetermined value close to 0 (a value slightly larger than the drive current (leakage current or the like) flowing in the stopped state) can be used.

(B) Second Embodiment Next, a second embodiment of the present invention will be described. FIG. 4 is a block diagram illustrating a configuration example of the laser diode control device 1A according to the second embodiment. In FIG. 4, portions corresponding to those in FIG. In FIG. 4, the laser operation monitoring unit 10 is replaced with a laser operation monitoring unit 10A as compared with FIG. Other configurations are the same as those in FIG. In the laser operation monitoring unit 10A, the threshold value changing unit 13 is excluded, and the alarm determination unit 14 is replaced with an alarm determination unit 14A (corresponding to a part of “determination means” in the claims). Here, the alarm determination unit 14A has two functions. First, the alarm determination unit 14A compares the current monitor value supplied from the current monitor unit 30 with a determination threshold (corresponding to the first determination threshold in FIG. 3), and the current monitor value is greater than the determination threshold. If is too large, it is determined that an abnormality has occurred and an alarm is issued. Secondly, the alarm determination unit 14A compares the current monitor value supplied from the current monitor unit 30 with the current instruction value supplied from the current instruction unit 11, and these are deviated by a predetermined value or more. In this case, it is determined that an abnormality has occurred and an alarm is issued.

Next, the operation of the second embodiment will be described.
First, the current instruction unit 11 supplies a current instruction value corresponding to the light intensity of the laser light to be output from the laser diode 110 to the laser diode driving unit 20. The laser diode drive unit 20 drives the laser diode 110 based on the ON / OFF signal supplied from the ON / OFF instruction unit 12 and the current instruction value supplied from the current instruction unit 11. Specifically, when the ON / OFF signal is ON, a drive current corresponding to the current instruction value supplied from the current instruction unit 11 is supplied to the laser diode 110. Further, when the ON / OFF signal is OFF, the drive current is not supplied to the laser diode 110 regardless of the current instruction value supplied from the current instruction unit 11.

  The alarm determination unit 14A compares the current monitor value supplied from the current monitor unit 30 with the determination threshold value, and determines that the current monitor value is smaller than the determination threshold value, and determines that the current value is normal. It is determined that has occurred and an alarm is issued. Further, the alarm determination unit 14A compares the current instruction value supplied from the current instruction unit 11 with the current monitor value supplied from the current monitor unit 30, and when these are more than a predetermined value (for example, When the current monitor value deviates from the current instruction value by ± 30% or more), it is determined that an abnormality has occurred and an alarm is issued. It should be noted that “± 30%” is an example, and other values may be used.

  As described above, in the second embodiment of the present invention, the current instruction value and the current monitor value are compared, and if they are more than a predetermined value, an abnormality has occurred. Since the alarm is issued, for example, the case where the laser diode driving unit 20 does not output according to the current instruction value can be detected and the alarm can be issued. Thus, by preventing the difference between the current instruction value and the current monitor value, it is possible to prevent laser light with an inappropriate intensity from being emitted or the laser diode 110 from being deteriorated due to an inappropriate output.

  In the second embodiment described above, one type of determination threshold is used as in the conventional case, but the determination is made using the first and second determination thresholds as in the first embodiment. It goes without saying. Moreover, although the case where the current monitor value deviates from the current instruction value by ± 30% or more has been described as an example as a reference for issuing an alarm, it goes without saying that other values may be used. .

(C) Third Embodiment Next, a third embodiment of the present invention will be described. FIG. 5 is a block diagram illustrating a configuration example of the laser diode control device 1B according to the third embodiment. In FIG. 5, the same reference numerals are given to the portions corresponding to those in FIG. In FIG. 5, compared with FIG. 1, the laser diode 110 is replaced with a laser device 120, the laser operation monitoring unit 10 is replaced with a laser operation monitoring unit 10B, and a light intensity monitoring unit 40 is newly added. Yes. Other configurations are the same as those in FIG. The laser device 120 includes a laser diode 121 and a photodiode 122 (corresponding to “detection means” in claims) as main components. The laser diode 121 is operated by a driving current supplied from the laser diode driving unit 20. The photodiode 122 divides a part of the laser light emitted from the laser diode 121 by, for example, a splitter, converts the branched light into a corresponding electric signal by photoelectric conversion, and outputs it to the light intensity monitor unit 40. . The light intensity monitor unit 40 monitors the electrical signal output from the photodiode 122 and supplies it as a light intensity monitor value to the threshold value changing unit 13B (corresponding to a part of “determination means” in the claims).

  In the laser operation monitoring unit 10B, as compared with FIG. 1, the threshold value changing unit 13 is replaced with a threshold value changing unit 13B. The threshold value changing unit 13B changes the determination threshold value based on the light intensity monitor value supplied from the light intensity monitor unit 40, not the ON / OFF signal from the ON / OFF instruction unit 12.

  Next, the operation of the third embodiment will be described. The third embodiment is different from the first embodiment in that the threshold changing unit 13B changes the threshold based on the light intensity monitor value supplied from the light intensity monitoring unit 40. The explanation will be centered.

  The laser diode drive unit 20 supplies a drive current to the laser diode 121 based on the current instruction value from the current instruction unit 11 and the ON / OFF signal from the ON / OFF instruction unit 12. The laser diode 121 emits a laser beam corresponding to the drive current supplied from the laser diode driver 20. The photodiode 122 converts a part of the laser light emitted from the laser diode 121 into a corresponding electric signal and supplies it to the light intensity monitor unit 40. The light intensity monitor unit 40 generates a light intensity monitor value based on the electrical signal supplied from the photodiode 122 and outputs the light intensity monitor value to the threshold value changing unit 13B.

  The threshold value changing unit 13B receives the light intensity monitor value output from the light intensity monitor unit 40. For example, when the light intensity monitor value is 0 or a value close thereto (for example, several mW), the laser diode 121 is used. Is determined to be in a stopped state, and the second determination threshold value is supplied to the alarm determination unit 14; otherwise, it is determined that the laser diode 121 is in the operating state and the first determination threshold value is set to the alarm determination unit 14. To supply.

  The alarm determination unit 14 compares the first determination threshold value or the second determination threshold value supplied from the threshold value changing unit 13B with the current monitor value supplied from the current monitor unit 30, and makes the same determination as in the first embodiment ( Based on (see FIG. 2), it is determined whether or not an abnormality has occurred, and if an abnormality has occurred, an alarm is issued.

  According to the third embodiment described above, since the determination threshold value is changed based on the intensity change of the output light of the laser diode 121, the selected determination threshold value and the state of the laser diode 121 (operating state or stopped state). ) Can be prevented from occurring. Specifically, for example, when the current monitor value and the value of the ON / OFF signal are inconsistent due to a signal delay or the like in the laser diode driving unit 20, a determination is made and an erroneous determination is made. Can be prevented.

  Further, according to the third embodiment, it is possible to detect a failure of the current monitor unit 30, the light intensity monitor unit 40, the laser device 120, and the like. That is, when the second determination threshold is selected, the light intensity monitor value is 0 or a value close thereto (because the light output is stopped). In such a case, the current monitor value is 0. If it is not a value close to that (for example, if it is 100 mA), (1) it is erroneously recognized as 100 mA due to the failure of the current monitor unit 30 even though it is actually 0 mA, or (2) Although the current of 100 mA actually flows through the laser diode 121, the light intensity monitor value may not be normally output due to the failure of the laser diode 121, the photodiode 122, the light intensity monitor unit 40, or the like. Conceivable. In the third embodiment, when the light intensity monitor value is 0 or a value close to 0, the second determination threshold is set. Therefore, even in the cases of (1) and (2) described above. Since an alarm can be issued, it is possible to detect a failure in the current monitor unit 30, the light intensity monitor unit 40, the laser device 120, and the like.

  In the third embodiment described above, as in the second embodiment, the current instruction value from the current instruction unit 11 and the current monitor value from the current monitor unit 30 are compared, and these values deviate by a certain value or more. If so, the alarm determination unit 14 may issue an alarm.

(D) Fourth Embodiment Next, a fourth embodiment of the present invention will be described. FIG. 6 is a block diagram illustrating a configuration example of a laser diode control device 1C according to the fourth embodiment. In FIG. 6, parts corresponding to those in FIG. In the example of FIG. 6, compared with FIG. 1, the laser operation monitoring unit 10 is excluded, and a laser operation unit 10C (corresponding to “switching means” in the claims) and a laser monitoring unit 50 are newly added. The rest is the same as in the case of FIG.

  Here, the laser operation unit 10C includes the current instruction unit 11 and the ON / OFF instruction unit 12 as main components. The laser operation unit 10C generates a state signal indicating its own operation state and outputs it to the laser monitoring unit 50.

  The laser monitoring unit 50 includes an operation state monitoring unit 51, a threshold value changing unit 13, and an alarm determination unit 14 as main components. Here, the operation state monitoring unit 51 refers to the state signal output from the laser operation unit 10C, and stops the operation of the laser operation unit 10C when an abnormality is detected. Other configurations are the same as those in FIG.

  Next, the operation of the fourth embodiment will be described. In the fourth embodiment, the operations of the laser operation unit 10C and the operation state monitoring unit 51 are different from those in the first embodiment, and other operations are the same as those in FIG. Therefore, hereinafter, the operation will be described focusing on these portions.

  The laser operation unit 10C generates and outputs a state signal indicating its own operation state. As an example, a signal output from the ON / OFF instruction unit 12 can be used as a 1-bit status signal. That is, the ON / OFF instruction signal output from the ON / OFF instruction unit 12 is “1” when ON, and “0” when OFF, and these are used as signals that are alternately repeated. Can do.

  The operation state monitoring unit 51 determines whether or not the state signal output from the laser operation unit 10C is abnormal, and if it is abnormal, issues an alarm. In this example, when the status signal no longer changes (when it does not change from “1” or “0”), or when the status change is abnormal (“1” and “0” alternate regularly) If the laser operation unit 10C does not change, the laser operation unit 10C may be out of order, so an alarm is issued and the operation of the laser operation unit 10C is stopped (reset). When the operation of the laser operation unit 10C is stopped, it is not preferable that the drive current is supplied from the laser diode driving unit 20 to the laser diode 110. Therefore, when the operation of the laser operation unit 10C is stopped, The ON / OFF instruction section 12 outputs a signal indicating OFF (for example, signal “0”), and the current instruction section 11 outputs a signal indicating that no current flows (for example, signal “0”). By doing so, it is possible to prevent the drive current from being supplied from the laser diode driver 20 to the laser diode 110.

  As described above, in the fourth embodiment, the laser operation unit 10C generates and outputs a state signal indicating its own operation state, and the operation state monitoring unit 51 determines whether the state signal is correct and is not normal. In this case, the operation of the laser operation unit 10C is stopped. Therefore, when the laser operation unit 10C is abnormal, the operation is stopped to prevent the laser diode 110 from being loaded. Further, when the operation of the laser operation unit 10C is stopped, the laser diode driving unit 20 is stopped in a state where no driving current is output, so that it is possible to prevent the laser diode 110 from being loaded.

  In the fourth embodiment described above, the ON / OFF instruction signal from the ON / OFF instruction unit 12 is used as the status signal. However, other signals may be used. Specifically, “1” is always output when the laser operation unit 10C is operating, and even if a status signal other than “1” is detected, it is determined that there is an abnormality. Good. Alternatively, when a signal of 2 bits or more is cyclically counted up or down at a predetermined timing (for example, in synchronization with the ON / OFF instruction signal) and the count up or count down is not performed normally. It may be determined that an abnormality has occurred. As the number of bits increases, the probability that the previous value and the current value coincide with the correct value by chance can be lowered, so the probability of misjudgment is lowered and the number of judgments until the final judgment on whether there is an abnormality is made Can be reduced.

  In the fourth embodiment described above, the determination threshold value of the threshold value changing unit 13 is changed based on the ON / OFF instruction signal from the ON / OFF instruction unit 12, but the photodiode 122 is used as in the third embodiment. May be changed based on the light intensity monitor value supplied via the light intensity monitor unit 40. Further, as in the second embodiment, the current instruction value from the current instruction unit 11 is compared with the current monitor value, and an alarm is issued when these values are more than a predetermined value. Also good.

(E) Fifth Embodiment Next, a fifth embodiment of the present invention will be described. FIG. 7 is a block diagram illustrating a configuration example of a laser diode control device 1D according to the fifth embodiment. In FIG. 7, only the temperature control and abnormality monitoring of the laser device 80 are described. The circuit for driving the laser diode 121 has the same configuration as that shown in FIG. 1 or FIG.

  In the block diagram shown in FIG. 7, a laser device 80 includes a laser diode 121, a TEC (Thermoelectric Cooler) 81 (corresponding to “cooling means” in the claims), and a thermistor 82 (corresponding to “detecting means” in the claims). Is the main component. Here, the laser diode 121 is controlled by a laser diode driver 20 (not shown) and emits laser light. The laser diode 121 is disposed on a heat conductive substrate common to the TEC 81 and the thermistor 82, and these are thermally coupled to each other. The TEC 81 is configured by, for example, a Peltier element, and cools the thermally conductive substrate according to the control of the temperature control unit 70. The thermistor 82 detects the temperature of the laser diode 121 or the heat conductive substrate and supplies it to the temperature monitor unit 71.

  The laser operation monitoring unit 60 includes a temperature instruction unit 61, a threshold value changing unit 62 (corresponding to a part of “determination unit” in the claims), an alarm determination unit 63 (corresponding to a part of “determination unit” in the claims), The ON / OFF instruction unit 64 is a main component, and controls the temperature of the laser device 80 and performs an abnormality monitoring process. Here, the temperature instruction unit 61 supplies a temperature instruction value as a control target temperature of the laser device 80. The threshold changing unit 62 changes the determination threshold based on the ON / OFF signal from the ON / OFF instruction unit 64. The alarm determination unit 63 compares the temperature monitor value supplied from the temperature monitor unit 71 with the determination threshold value supplied from the threshold value changing unit 62, and issues an alarm when an abnormality occurs. The ON / OFF instruction unit 64 notifies the temperature control unit 70 of whether temperature control is on or off.

  The temperature control unit 70 controls the TEC 81 according to the temperature instruction value from the temperature instruction unit 61 and the ON / OFF signal from the ON / OFF instruction unit 64. The temperature monitor unit 71 generates a temperature monitor value based on the electrical signal supplied from the thermistor 82 and supplies the temperature monitor value to the temperature control unit 70 and the alarm determination unit 63.

  Next, the operation of the fifth embodiment will be described. The control related to driving of the laser diode 121 of the fifth embodiment is the same as that of the third embodiment shown in FIG. In the fifth embodiment, when the ON / OFF instruction unit 64 indicates the ON state, the temperature control unit 70 includes the temperature instruction value (control target temperature) supplied from the temperature instruction unit 61 and the temperature monitoring unit. The temperature monitor value indicating the current temperature of the laser device 80 supplied from 71 is compared, and the TEC 81 is controlled so that they are equal. The laser diode 121 is driven according to an ON / OFF signal supplied from an ON / OFF instruction unit 12 (not shown), and generates heat in the driving state, so that the temperature of the laser device 80 rises. The thermistor 82 senses the temperature rise and notifies the temperature control unit 70 via the temperature monitor unit 71. When the ON / OFF signal supplied from the ON / OFF instruction unit 64 instructs the temperature control to turn on, the temperature control unit 70 determines that the temperature monitor value and the temperature instruction value output from the temperature instruction unit 61 are The TEC 81 is controlled to be equal. As a result, the laser device 80 is controlled to reach the target temperature regardless of the operation of the laser diode 121. The temperature control unit 70 does not perform temperature control when the ON / OFF signal supplied from the ON / OFF instruction unit 64 instructs the temperature control to be turned off.

  The threshold change unit 62 outputs the threshold to the alarm determination unit 63 based on an instruction from the ON / OFF instruction unit 64. Specifically, when the ON / OFF instruction unit 64 instructs to turn on (temperature control operation state), a predetermined temperature (for example, a control target) higher than the temperature instruction value output by the temperature instruction unit 61 is determined. Temperature + 10 ° C.) is output to the alarm determination unit 63 as the first determination threshold. In addition, when the ON / OFF instruction unit 64 instructs OFF (temperature control stop state), for example, a value determined according to the environmental temperature (for example, the environmental temperature itself or the predetermined temperature from the environmental temperature). A value (for example, a value obtained by adding or subtracting 5 ° C.) is output to the alarm determination unit 63 as the second determination threshold. As the environmental temperature, for example, an operating temperature expected in an average operating environment is set in advance, or a temperature output from the thermistor 82 at the start of operation is set as the environmental temperature. It may be. As a specific example, for example, 70 ° C. can be set as the environmental temperature, and 25 ° C. can be set as the control target temperature. Of course, depending on the operating environment, the season, etc., it is naturally assumed that these temperatures may be lower or higher.

  The alarm determination unit 63 compares the temperature monitor value with the first determination threshold value when the ON / OFF instruction unit 64 instructs ON, and if the temperature monitor value exceeds the first determination threshold value (or a predetermined value) An alarm is issued when the value of (for example, 10 ° C. or more) deviates. Further, when the ON / OFF instruction unit 64 instructs OFF, the temperature monitor value is compared with the second determination threshold value, and the temperature monitor value is equal to or greater than a predetermined value (for example, 10 ° C.) from the second determination threshold value. If there is a divergence, an alarm is issued.

  According to the fifth embodiment described above, since the temperature control of the laser device 80 is performed, it is possible to prevent the temperature of the laser diode 121 from becoming too high.

  In the fifth embodiment, since the alarm determination unit 63 detects a temperature abnormality and issues an alarm, the laser diode 121 can be prevented from being damaged by heating. Furthermore, in the fifth embodiment, the first threshold value when the temperature control is in the operating state and the second threshold value when the temperature control is in the stopped state are provided. Thereby, when the temperature control is in the operating state, it is determined whether or not the temperature control is normal by comparison with the first determination threshold value near the target temperature. When the temperature control is in the stopped state, the second temperature near the environmental temperature is determined. By comparison with the determination threshold, for example, when the temperature control is instructed to stop, the TEC 81 operates (temperature control runs out of control), and it is determined that the temperature is deviated from the environmental temperature. can do.

  In the above fifth embodiment, only the alarm determination unit 63 is described, but the first embodiment shown in FIG. 1, the second embodiment shown in FIG. 4, or the third embodiment shown in FIG. Similarly, an alarm may be issued based on the comparison between the current monitor value and the determination threshold value. Moreover, you may make it stop operation | movement of a laser operation part based on status information similarly to 4th Embodiment shown in FIG.

(F) Sixth Embodiment Next, a sixth embodiment of the present invention will be described. FIG. 8 is a block diagram showing a configuration example of a laser diode control device 1E according to the sixth embodiment. In FIG. 8, parts corresponding to those in the first and third embodiments shown in FIGS. 1 and 5 are denoted by the same reference numerals, and the description thereof is omitted. In FIG. 8, for example, compared with FIG. 5, the laser operation monitoring unit 10B is replaced with a laser operation monitoring unit 10E. Other configurations are the same as those in FIG.

  The laser operation monitoring unit 10E includes a current instruction unit 11, an ON / OFF instruction unit 12, a threshold change unit 13E (corresponding to a part of “determination means” in the claims), and an alarm determination unit 14E (“determination” in claims). Corresponds to a part of “means”) as a main component. Here, the functions of the current instruction unit 11 and the ON / OFF instruction unit 12 are the same as those in FIGS. The alarm determination unit 14E compares the light intensity monitor value supplied from the light intensity monitor unit 40 with the determination threshold value related to the light intensity supplied from the threshold value changing unit 13E, and issues an alarm if an abnormality is detected. To do. Specifically, as shown in FIG. 9, the threshold value changing unit 13E sets a predetermined light intensity higher than the output light intensity normally output when the laser diode 121 is on (see the left side of FIG. 9) as the first determination threshold value. A predetermined light intensity (a predetermined value close to 0 mW (see the right side in FIG. 9)) higher than the normal output light intensity that is normally output when the laser diode 121 is off is set as the second determination threshold value. When the laser diode 121 is on, the alarm determination unit 14E issues an alarm when the light intensity monitor value output from the light intensity monitor unit 40 is greater than the first determination threshold supplied from the threshold change unit 13E. When the laser diode 121 is off, an alarm is issued when the light intensity monitor value is larger than the second determination threshold value supplied from the threshold value changing unit 13E.

  Next, the operation of the sixth embodiment will be described. Note that the sixth embodiment differs from the first and third embodiments in the operations of the threshold value changing unit 13E and the alarm determination unit 14E, and will be described focusing on that point.

  The threshold value changing unit 13E selects the first determination threshold value shown in FIG. 9 when the ON / OFF signal from the ON / OFF instruction unit 12 is on, and selects the second determination threshold value when it is off. And supplied to the alarm determination unit 14E. The alarm determination unit 14E compares the light intensity monitor value supplied from the light intensity monitor unit 40 with the first or second determination threshold value supplied from the threshold value changing unit 13E, and the light intensity monitor value is the determination threshold value. If it is larger than that, it is determined that an abnormality has occurred, an alarm is issued, and otherwise, it is determined that it is normal. Thereby, when the intensity of the laser beam emitted from the laser diode 121 is in an abnormal state (when the determination threshold is exceeded), an alarm is issued, so that the abnormality can be reliably detected. Further, since the determination threshold is set for each of the on time and the off time, it is possible to detect the presence or absence of abnormality not only at the on time but also at the off time. Furthermore, since the presence or absence of an abnormality is determined based on the light intensity, it is possible to know whether or not the laser diode 121 is overloaded, and by detecting that light is being output in the off state, the laser diode A failure of the drive unit 20 can be detected.

  In the above sixth embodiment, a value larger than the light intensity that is normally output at the time of ON is set as the first determination threshold. However, for example, a value smaller than the light intensity that is normally output is defined as the first determination threshold. By doing so, it is possible to detect the deterioration of the laser diode 121.

  Further, in the sixth embodiment described above, as in the second embodiment shown in FIG. 4, the current instruction value and the current monitor value are compared, and an alarm is issued if they deviate by a predetermined value or more. In the same manner as in the fourth embodiment shown in FIG. 6, it is determined that there is an abnormality based on a state signal indicating a state of a laser operation unit (not shown) constituted by the current instruction unit 11 and the ON / OFF instruction unit 12. In such a case, an alarm may be issued, or abnormality determination based on temperature may be performed together with the fifth embodiment shown in FIG.

(D) Modified Embodiments Each of the above-described embodiments is an example, and there are various modified embodiments other than this. For example, in each of the embodiments described above, the alarm determination unit, the threshold value changing unit, the current monitoring unit, the light intensity monitoring unit, and the temperature monitoring unit are configured separately, but these may be appropriately combined into an integrated configuration. Good.

  In each of the above embodiments, the case where each functional unit is configured as hardware has been described as an example. However, these functions may be realized by software executed on the hardware.

  Further, double or triple abnormality detection may be executed by appropriately combining the above embodiments. According to such a method, it is possible to further improve the accuracy of detecting an abnormality.

  In each of the above embodiments, the first and second determination threshold values are fixed, but these may be rewritable, for example. Specifically, for example, these values are stored in a rewritable semiconductor memory, and for example, an optimum value considering variation of each device in the production line is selected and stored, or After manufacturing, the optimum value according to the installation environment may be set later.

  Further, in each of the above embodiments, the presence / absence of abnormality is determined based on the magnitude relationship between the determination threshold and the monitor value. For example, when the monitor value deviates from the determination threshold by a predetermined value or more. It may be determined that an abnormality has occurred.

  In the third embodiment described above, the first and second determination threshold values are selected based on the light intensity monitor. However, other than this, for example, the current monitor value detected by the current monitor unit 30 The determination threshold value may be selected based on the magnitude, or the determination threshold value may be selected based on the temperature monitor value detected by the temperature monitor unit 71.

1, 1A, 1B, 1C, 1D, 1E Laser diode control device 10, 10A, 10B, 10E Laser operation monitoring unit 10C Laser operation unit (switching means)
11 Current indicating unit 12 ON / OFF indicating unit (part of switching means)
13, 13B, 13E Threshold change unit (part of determination means)
14, 14A, 14E Alarm judgment part (part of judgment means)
20 Diode drive unit (drive means)
30 Current monitor (detection means)
40 Light intensity monitor unit 50 Laser monitoring unit 51 Operation state monitoring unit 60 Laser operation monitoring unit 61 Temperature indicating unit 62 Threshold changing unit (part of determination means)
63 Alarm judgment part (part of judgment means)
64 ON / OFF instruction unit 70 Temperature control unit 71 Temperature monitoring unit 80 Laser device 81 TEC (cooling means)
82 Thermistor (detection means)
110, 121 Laser diode 120 Laser device 122 Photodiode (detection means)

Claims (9)

In a laser diode controller for controlling a laser diode,
Driving means for driving the laser diode;
Switching means for switching between an operating state in which a driving current is supplied to the laser diode by the driving means and a stopped state in which the supply of the driving current is stopped;
Detecting means for detecting a state of the laser diode;
When the laser diode is in the operation state, the detection result of the detection means is compared with a first determination threshold value to determine whether there is an abnormality. When the laser diode is in the stop state, Determination means for comparing the detection result of the detection means and a second determination threshold different from the first determination threshold to determine the presence or absence of abnormality;
A laser diode control device comprising: The detecting means detects the drive current of the laser diode;
The first determination threshold is a predetermined value larger than the drive current in the operating state of the laser diode, and the second determination threshold is smaller than the first determination threshold and is a predetermined value close to 0 or 0 Is,
The laser diode control device according to claim 1. The switching means outputs state information indicating its own state,
The determination means determines that an abnormality has occurred when the state information of the switching means is not normal;
The laser diode control device according to claim 1 or 2, wherein   4. The laser diode control device according to claim 3, wherein when the determination unit determines that an abnormality has occurred based on the state information, the operation of the switching unit is stopped in a stopped state. The detecting means detects the drive current of the laser diode;
The determination means compares the set value of the drive current in the operating state with the actual drive current value detected by the detection means, and determines that it is abnormal if they differ by a predetermined value or more. The laser diode control device according to claim 1, wherein the laser diode control device is a laser diode control device. The detection means detects the output light intensity of the laser diode,
The first determination threshold is a predetermined value larger than the output light intensity in the operating state of the laser diode, and the second determination threshold is smaller than the first determination threshold and is a predetermined value close to 0 or 0 Value,
6. The laser diode control device according to claim 1, wherein the laser diode control device is a laser diode control device. Cooling means for cooling the laser diode;
The detection means detects the temperature of the laser diode itself or its surroundings,
The determination means has a first determination threshold value higher than a control target temperature by the cooling means and a second determination threshold value determined by an environmental temperature, and the first determination threshold value when the cooling means is in an operating state. Is compared with the temperature detected by the detection means, and in the stop state, the second determination threshold is compared with the temperature detected by the detection means, and the presence / absence of an abnormality is determined based on the magnitude relationship between them. To
The laser diode control device according to claim 1, wherein the laser diode control device is a laser diode control device.   The said determination means selects the said 1st determination threshold value or the said 2nd determination threshold value based on the magnitude relationship of the detection result by the said detection means in each of the said operation state or the said stop state. The laser diode control device according to any one of 1 to 7. In a laser diode control method for controlling a laser diode,
A switching step of switching between an operating state for supplying a driving current to the laser diode and a stopped state for stopping the supply of the driving current;
A detecting step for detecting a state of the laser diode;
When the laser diode is in the operating state, the detection result of the detection step is compared with a first determination threshold value to determine whether there is an abnormality. When the laser diode is in the stopped state, A determination step of comparing the detection result of the detection step with a second determination threshold value different from the first determination threshold value to determine whether there is an abnormality;
A method for controlling a laser diode, comprising:

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