JP5781469B2 - LED driving device and lighting apparatus - Google Patents

Description

  The present invention relates to an LED driving device and a lighting fixture, and more particularly, to an LED driving device and a lighting fixture capable of performing dimming of an LED module.

  In recent years, in lighting fixtures or the like, LED modules formed by connecting a plurality of LED units each having LEDs (light emitting diodes) connected in series have been used as a light source. As an LED drive device used for such a lighting fixture, there is one that performs drive control such as interruption of current in response to occurrence of an abnormal state such as an abnormal current flowing through the LED.

  Patent Document 1 below discloses a configuration of an LED drive circuit provided in an illumination device including an LED group. The LED group is configured by connecting a series connection body in which a plurality of LEDs are connected in series in parallel in a plurality of rows. In this LED drive circuit, when an abnormal current flows in any of a plurality of series connected bodies, the current of the series connected body in which the abnormal current flows is cut off. Moreover, in this LED drive circuit, when the output voltage supplied to the LED group becomes an overvoltage, the current of all the columns of the series connection body is cut off.

JP 2009-252344 A

  The above LED driving device is configured such that when an abnormal state occurs, a protective operation is performed in the LED driving device by a closed loop control circuit corresponding to the type of abnormality that has occurred. However, depending on the configuration of such an LED drive device, when dimming control is performed, it is not possible to accurately detect whether or not an abnormality has actually occurred inside the LED drive device. There was a problem.

  That is, in the LED driving device as described above, when a plurality of LEDs are short-circuited or opened in one LED unit, the current flowing through each LED unit becomes non-uniform. Therefore, the drive voltage of each LED unit is lowered until a balance is achieved among the LED units.

  Here, when the LED module is dimmed, the forward voltage VF (forward voltage) of the LED fluctuates. In other words, the drive voltage of the LED module varies depending on the dimming state. Therefore, in the method for detecting an abnormal state using the above LED driving device, it is difficult to detect an abnormality even when a plurality of LEDs are short-circuited or opened in one LED unit.

  This invention was made in order to solve such a problem, and it aims at providing the LED drive device and lighting fixture which can perform the detection of the abnormal condition according to a light control state appropriately. .

In order to achieve the above object, according to one aspect of the present invention, a plurality of LED units composed of one LED or two or more LEDs connected in series are connected in parallel according to a dimming instruction signal. The LED driving device that performs dimming operation of the configured LED (light emitting diode) module is connected to the LED module and a driving circuit unit that outputs driving power to the LED module, and detects a current flowing through the LED module. The current detection circuit that outputs the detection voltage corresponding to the detection result, the detection voltage output from the current detection circuit and the threshold voltage corresponding to the dimming instruction signal are compared, and the abnormality of the LED module is determined according to the comparison result and a control circuit section for detecting the state, the threshold voltage, in each of the plurality of light control direction signal, a predetermined number, LED short detection number or L Corresponding to the number of open detections of the D unit, the control circuit unit outputs a comparison result when the detection voltage is within a predetermined range where the number of LED short detections or the number of open detections of the LED unit does not exceed the predetermined number. Accordingly, when the abnormal state is not detected and the detected voltage is an abnormal voltage that is not within the predetermined range, the abnormal state is detected according to the comparison result.

  Preferably, the control circuit unit stores in advance a dimming table storage unit that stores dimming rate information corresponding to each of the plurality of dimming instruction signals, and information on threshold voltages corresponding to each of the plurality of dimming instruction signals The threshold voltage table storage unit for storing the light, the dimming rate acquisition unit for acquiring the dimming rate information corresponding to the dimming instruction signal based on the information stored in the dimming table storage unit, and the threshold voltage table storage unit A threshold voltage acquisition unit that acquires a threshold voltage corresponding to the dimming instruction signal based on the information to be generated, and a generation information output that outputs PWM signal generation information based on the dimming rate information acquired by the dimming rate acquisition unit A PWM signal generation unit that generates a PWM dimming signal based on the PWM signal generation information output by the generation information output unit, and outputs the generated PWM dimming signal to the drive circuit unit, and threshold voltage acquisition It has a threshold voltage that is acquired, and an abnormality detection unit which compares the detection voltage input from the current detection circuit detects an abnormal state of the LED module according to the comparison result by.

  Preferably, the control circuit unit preliminarily stores the dimming rate information corresponding to each of the plurality of dimming instruction signals, and the dimming instruction signal based on the information stored in the dimming table storage unit A dimming rate acquisition unit that acquires dimming rate information corresponding to the above, a generation information output unit that outputs PWM signal generation information based on the dimming rate information acquired by the dimming rate acquisition unit, and a generation information output A PWM signal generation unit that generates a PWM dimming signal based on the PWM signal generation information output by the unit and outputs the generated PWM dimming signal to the drive circuit unit, and a dimming acquired by the dimming rate acquisition unit Based on the rate information and the dimming instruction signal, the threshold voltage calculating unit that calculates the threshold voltage corresponding to the dimming instruction signal, the threshold voltage calculated by the threshold voltage calculating unit, and the detection input from the current detection circuit Compare the voltage and And a failure detection unit for detecting an abnormal state of the LED module in accordance with the comparison result.

  Preferably, the control circuit unit controls the drive circuit unit to stop or reduce the power supply to the LED module when detecting an abnormal state of the LED module.

  Preferably, the control circuit unit is driven when the abnormality detection unit detects an abnormal state of the LED module, and when the error determination signal is input from the determination signal output unit and the determination signal output unit that outputs an error determination signal. An error signal generation unit that outputs an error signal to the circuit unit;

According to another aspect of the present invention, the luminaire drives an LED module, in which a plurality of LED units each composed of one LED or two or more LEDs connected in series are connected in parallel. The LED driving device described above and a dimming control device that outputs a dimming instruction signal to the LED driving device.

  According to these inventions, the control circuit unit compares the detection voltage output from the current detection circuit with the threshold voltage corresponding to the dimming instruction signal, and can detect the abnormal state of the LED module according to the comparison result. Therefore, it is possible to provide an LED driving device and a lighting fixture that can appropriately detect an abnormal state according to a dimming state.

It is a block diagram which shows the structure of the lighting fixture using the LED drive device in the 1st Embodiment of this invention. It is a block diagram which shows the structure of an LED drive device and an LED module. It is a flowchart explaining the procedure of the processing operation in the calculating part of an LED drive device. It is a block diagram which shows the structure of the LED drive device and LED module in the 2nd Embodiment of this invention. It is a flowchart explaining the procedure of the processing operation in the calculating part of the LED drive device of 2nd Embodiment.

  Hereinafter, the lighting fixture using the LED drive device in embodiment of this invention is demonstrated.

  [First Embodiment]

  FIG. 1 is a block diagram illustrating a configuration of a lighting fixture using the LED driving device according to the first embodiment of the present invention.

  As shown in FIG. 1, the lighting fixture 100 includes an LED driving device 1, an LED module 10, and a dimming control device 20. The luminaire 100 performs illumination when the LED module 10 is driven and turned on.

  The LED driving device 1 is connected to the LED module 10. The LED driving device 1 drives the LED module 10.

  In the present embodiment, the LED driving device 1 is connected to the dimming control device 20. The dimming control device 20 outputs a dimming instruction signal Sad to the LED driving device 1. The LED driving device 1 performs a dimming operation of the LED module 10 based on the dimming instruction signal Sad sent from the external dimming control device 20. That is, in the illumination device 100, the brightness of illumination by the LED module 10 can be changed.

  The dimming instruction signal Sad is, for example, a digital signal.

  The dimming control device 20 is, for example, a remote controller provided in the lighting fixture 100 in order to change the brightness. The connection between the light control device 20 and the LED driving device 1 may be wired or wireless. For example, when the dimming control device 20 and the LED driving device 1 are connected wirelessly, the dimming control device 20 is provided with a light emitting unit, the LED driving device 1 is provided with a light receiving unit, and infrared communication is performed between the two. It may be configured to perform.

  FIG. 2 is a block diagram illustrating configurations of the LED driving device 1 and the LED module 10.

  As shown in FIG. 2, in this embodiment, the LED module 10 has LED units 10a and 10b formed by connecting a plurality of LEDs in series. The LED module 10 is configured by connecting an LED unit 10a and an LED unit 10b in parallel.

  The LED module 10 is not limited to the two LED units 10a and 10b, and more LED units may be provided. For example, the LED module 10 may be configured by connecting three or more LED units 10a, 10b,. LED unit 10a, 10b is not restricted to what has several LED, You may have one LED. For example, the LED module 10 may be composed of a plurality of LEDs connected one by one in parallel.

  The LED drive device 1 includes a DC / DC converter (an example of a drive circuit unit) 2, a current detection circuit 3, and a control circuit unit 4. The LED module 10 is connected to the DC / DC converter 2 and the current detection circuit 3. A dimming instruction signal Sad is input to the control circuit unit 4. That is, the control circuit unit 4 is connected to the dimming control device 20.

  The DC / DC converter 2 is connected to a direct current power source Vcc. The DC / DC converter 2 outputs drive power to the LED module 10. Here, the PWM dimming signal Sc output from the control circuit unit 4 is input to the DC / DC converter 2. The DC / DC converter 2 changes the drive power output to the LED module 10 based on the input PWM dimming signal Sc, and performs the dimming operation of the LED module 10. The DC / DC converter 2 receives an error signal Se output from the control circuit unit 4 when an abnormal state occurs in the LED module 10 as will be described later. For example, the error signal Se is output from the control circuit unit 4 when both or one of the LED unit 10a and the LED unit 10b is in an open state or a short state. The DC / DC converter 2 changes the operation of outputting drive power to the LED module 10 based on the error signal Se. For example, the DC / DC converter 2 stops the operation of outputting the driving power to the LED module 10 when the error signal Se is sent.

  The current detection circuit 3 is connected to the LED module 10. The current detection circuit 3 detects a current flowing through the LED module 10 and outputs a detection voltage corresponding to the detection result. That is, the current detection circuit 3 detects the currents Ia and Ib flowing through the LED units 10a and 10b as voltage values, and outputs a detection voltage VL. The detection voltage VL is input to the control circuit unit 4.

  The current detection circuit 3 includes a resistor R1 connected to the cathode side terminal of the LED unit 10a and a resistor R2 connected to the cathode side terminal of the LED unit 10b. The resistors R1 and R2 are connected to terminals on the side not connected to the LED units 10a and 10b, respectively. The connecting portions of the resistors R1 and R2 are connected to the ground potential with the resistor R0 interposed therebetween, and are connected to the DC / DC converter 2. The current flowing through the LED module 10 is sent as a feedback signal Sf from the connection portion of the resistors R1 and R2 to the DC / DC converter 2. The DC / DC converter 2 performs feedback control of the driving power of the LED module 10 based on the feedback signal Sf.

  The current detection circuit 3 includes two diodes D1 and D2. The anode side terminal of the diode D1 is connected between the cathode side terminal of the LED unit 10a and the resistor R1. The anode side terminal of the diode D2 is connected between the cathode side terminal of the LED unit 10b and the resistor R2. The cathode-side terminals of the diodes D1 and D2 are connected to each other and are connected to the control circuit unit 4. The current detection circuit 3 outputs a detection voltage VL corresponding to the currents Ia and Ib flowing through the LED units 10a and 10b via the diodes D1 and D2.

  The control circuit unit 4 is a microcomputer, for example. The control circuit unit 4 compares the detection voltage VL output from the current detection circuit 3 with a threshold voltage corresponding to the dimming instruction signal Sad, and detects an abnormal state of the LED module 10 according to the comparison result. The control circuit unit 4 can detect as an abnormal state that the operating voltage of each LED unit 10a, 10b is an abnormal voltage not within a predetermined range. These operations are performed in the control circuit unit 4 when the control circuit unit 4 executes a predetermined control program, for example.

  2, the control circuit unit 4 includes a dimming table storage unit 41, a calculation unit (an example of a determination signal output unit, an example of a dimming rate acquisition unit, an example of a threshold voltage acquisition unit, and a generation information output. Unit, an example of an abnormality detection unit) 42, a PWM signal generation unit 43, a threshold voltage table storage unit 44, an A-D conversion unit 45, and an error signal generation unit 46.

  The dimming table storage unit 41 and the threshold voltage table storage unit 44 are, for example, a part of a storage area of a ROM (for example, a flash memory or an EEPROM) in the control circuit unit 4.

  The dimming table storage unit 41 stores dimming rate information Sa corresponding to each of the plurality of dimming instruction signals Sad in advance. That is, the dimming rate information Sa is information corresponding to the dimming rate when the LED driving device 1 drives the LED module 10. The dimming rate information Sa is, for example, a digital signal. Dimming rate information Sa corresponding to each of a plurality of dimming instruction signals Sad that can be supported by the lighting fixture 100 is set in advance. In the dimming table storage unit 41, each dimming instruction signal Sad and the corresponding dimming rate information Sa are associated with each other and stored as a lookup table. Note that the number of dimming steps (the number of dimming steps) that the LED driving device 1 can face is, for example, 20 steps.

  The threshold voltage table storage unit 44 stores in advance information (threshold voltage information) Ss relating to the threshold voltage corresponding to each of the plurality of dimming instruction signals Sad. The threshold voltage information Ss is, for example, a digital signal corresponding to each threshold voltage. The threshold voltage information Ss is calculated in advance corresponding to the dimming rate. In the threshold voltage table storage unit 44, each dimming instruction signal Sad and the corresponding threshold voltage information Ss are associated with each other and stored as a lookup table. In other words, in the present embodiment, the dimming rate information Sa and the threshold value are previously stored in the control circuit unit 4 so as to correspond to each of the dimming instruction signals Sad having the number of stages dimmable by the LED driving device 1. Voltage information Ss is stored. The threshold voltage information Ss is, for example, according to the LED module 10 to be driven by the LED driving device 1 (depending on the number of LED units 10a, 10b,..., The number of LEDs used in each unit, etc.). It suffices to be calculated.

  The calculation unit 42 obtains the dimming rate information Sa corresponding to the input dimming instruction signal Sad from the dimming table storage unit 41 as described later, generates PWM signal generation information Sp, and generates a PWM signal. To the unit 43. Further, the calculation unit 42 generates an error determination signal Sj and outputs it to the error signal generation unit 46 as described later. The PWM signal generation information Sp and the error determination signal Sj are, for example, digital signals.

  The PWM signal generation unit 43 is a timer, for example. The PWM signal generation unit 43 generates the PWM dimming signal Sc based on the PWM signal generation information Sp output from the calculation unit 42, and outputs the generated PWM dimming signal Sc to the DC / DC converter 2. The DC / DC converter 2 drives the LED module 10 based on the output PWM dimming signal Sc. Thereby, the dimming operation of the LED module 10 is performed based on the dimming instruction signal Sad input to the LED driving device 1.

  The AD converter 45 converts the detection voltage VL, which is an analog voltage, input from the current detection circuit 3 into a digital signal Vd. The converted digital signal Vd is sent to the calculation unit 42.

  When the error determination signal Sj output from the calculation unit 42 is input, the error signal generation unit 46 generates an error signal Se based on the error determination signal Sj. The generated error signal Se is output to the DC / DC converter 2.

  Here, the calculation unit 42 outputs the PWM signal generation information Sp and the error determination signal Sj by performing the following processing.

  In other words, the calculation unit 42 refers to the lookup table stored in the dimming table storage unit 41 and acquires the dimming rate information Sa corresponding to the dimming instruction signal Sad input to the calculation unit 42 (dimming control). It functions as a light rate acquisition unit). And the calculating part 42 produces | generates PWM signal generation information Sp so that the LED module 10 may be driven with the dimming rate corresponding to the dimming rate information Sa based on the acquired dimming rate information Sa. Accordingly, the generated PWM signal generation information Sp is output to the PWM signal generation unit 43 (functions as a generation information output unit).

  The calculation unit 42 refers to the lookup table stored in the threshold voltage table storage unit 44 and corresponds to the threshold voltage signal Ss corresponding to the dimming instruction signal Sad input to the calculation unit 42, that is, the threshold voltage. A digital signal is acquired (functions as a threshold voltage acquisition unit). Then, the calculation unit 42 compares the acquired digital signal with the digital signal Vd corresponding to the detection voltage VL input from the current detection circuit 3. In other words, the calculation unit 42 compares the threshold voltage corresponding to the dimming instruction signal Sad with the detection voltage VL output from the current detection circuit 3. The calculation unit 42 detects an abnormal state of the LED module 10 according to the comparison result (functions as an abnormality detection unit). The detection of the abnormal state may be performed as described below, for example. When an abnormal state of the LED module 10 is detected, the calculation unit 42 generates an error determination signal Sj and outputs it to the error signal generation unit 46 (functions as a determination signal output unit).

  The operation of the calculation unit 42 as described above is executed as follows, for example, when the calculation unit 42 executes a control program or the like stored in the calculation unit 42.

  FIG. 3 is a flowchart illustrating the procedure of the processing operation in the calculation unit 42 of the LED driving device 1.

  As shown in FIG. 3, in step S <b> 1, the calculation unit 42 determines whether or not the dimming instruction signal Sad is input. When the dimming instruction signal Sad is input (YES), the calculation unit 42 performs the process of step S2. When the dimming instruction signal Sad is not input (NO), the calculation unit 42 performs the process of step S7.

  In step S2, the calculation unit 42 calculates coordinate data according to the dimming instruction signal Sad. The coordinate data is data that specifies the position of information corresponding to the dimming instruction signal Sad in each table of the dimming table storage unit 41 and the threshold voltage table storage unit 44 corresponding to the dimming instruction signal Sad. When calculating the coordinate data, the calculation unit 42 performs the processes of step S3 and step S5.

  In step S <b> 3, the calculation unit 42 accesses the dimming table storage unit 41 to obtain dimming rate information Sa corresponding to the coordinate data. When the calculation unit 42 obtains the light control rate information Sa, the calculation unit 42 performs the process of step S4.

  In step S4, the calculation unit 42 generates the PWM signal generation information Sp based on the dimming rate information Sa. The calculation unit 42 outputs the generated PWM signal generation information Sp to the PWM signal generation unit 43. When the calculation unit 42 outputs the PWM signal generation information Sp, the calculation unit 42 returns to the process of step S1.

  On the other hand, in step S5, the calculation unit 42 accesses the threshold voltage table storage unit 44 to obtain threshold voltage information Ss corresponding to the coordinate data. When the calculation unit 42 obtains the threshold voltage information Ss, it performs the process of step S6.

  In step S6, the calculation unit 42 updates the threshold voltage based on the threshold voltage information Ss. When the threshold voltage is updated, the process of step S7 is performed.

  In step S7, the calculation unit 42 compares whether the digital signal Vd corresponding to the detection voltage VL is larger than the digital signal corresponding to the threshold voltage. That is, the calculation unit 42 compares whether or not the detection voltage VL is larger than the threshold voltage. If the calculation unit 42 determines that the detection voltage VL is greater than the threshold voltage (YES), the calculation unit 42 performs the process of step S8. When the calculation unit 42 determines that the detection voltage VL is equal to or lower than the threshold voltage (NO), the calculation unit 42 returns to the process of step S1.

  In step S <b> 8, the calculation unit 42 outputs the error determination signal Sj to the error signal generation unit 46. When the error determination signal Sj is output, the calculation unit 42 ends the processing operation.

  When the error signal generation unit 46 receives the error determination signal Sj sent from the calculation unit 42, the error signal generation unit 46 generates an error signal Se and outputs the error signal Se to the DC / DC converter 2. When receiving the error signal Se, the DC / DC converter 2 stops the power supply to the LED module 10. Thereby, the LED module 10 stops the light emission operation.

  As described above, in the present embodiment, the threshold voltage corresponding to the dimming state is selected, and the abnormal state of the LED module 10 is determined based on the comparison result between the threshold voltage and the detected voltage. Therefore, in any dimming state, it is possible to appropriately detect an abnormal state (open, short circuit, etc.) and control operation corresponding to the abnormal state.

  Furthermore, according to the present embodiment, it is possible to appropriately detect circuit open and short in the LED module 10, and thus it is possible to prevent the element temperature in the LED module 10 from rising to an abnormal value. Moreover, it can prevent that the temperature which the lighting fixture 100 emits rises to an abnormal value by mounting the LED drive device 1 in this Embodiment in the lighting fixture 100. FIG.

  In the threshold voltage table storage unit 44, the numerical value of the lookup table for the threshold voltage can be arbitrarily set. Therefore, it is easy to determine the number of detected LED shorts of the LED units 10a, 10b,. In other words, whether or not to stop the operation of the LED module 10 can be determined according to the number of shorted LEDs. For example, when one LED is short-circuited, it is not detected, and when two or more LEDs are short-circuited, the driving of the LED module 10 is stopped. Can do.

  As described above, the numerical values in the table regarding the threshold voltage can be set arbitrarily, so that it is easy to determine the number of open detections of the LED units 10a, 10b,. Become. In other words, whether to stop the operation can be determined according to the number of open LED units 10a, 10b,. For example, when one of the LED units 10a, 10b,... Becomes open, it is not detected, and it is detected that two or more of the LED units 10a, 10b,. Thus, the driving of the LED module 10 can be stopped.

  The control circuit unit 4 is configured using a microcomputer. Therefore, the control program (software) executed by the control circuit 4 can be easily rewritten.

  [Second Embodiment]

  Since the basic configuration of the lighting fixture using the LED driving device in the second embodiment is the same as that in the first embodiment, description thereof will not be repeated here. The second embodiment is different from the first embodiment in that a threshold voltage storage unit is provided instead of the threshold voltage table storage unit in the control circuit unit of the LED driving device.

  FIG. 4 is a block diagram showing the configuration of the LED driving device and the LED module according to the second embodiment of the present invention.

  As shown in FIG. 4, the LED driving device 101 according to the second embodiment includes the same DC / DC converter 2 and current detection circuit 3 as those in the first embodiment described above, and the first embodiment. The control circuit unit 104 is slightly different from the configuration. The control circuit unit 104 does not have the threshold voltage table storage unit 44 but has a threshold voltage storage unit 147 instead. The other configuration of the control circuit unit 104 is the same as the configuration of the control circuit unit 4 of the first embodiment.

  In the second embodiment, the threshold voltage information Ss is calculated based on the dimming rate information Sa acquired by the calculation unit 42 and the dimming instruction signal Sad input to the control circuit unit 104. The calculation of the threshold voltage information Ss is performed by, for example, the calculation unit 42 (the calculation unit 42 functions as a threshold voltage calculation unit). The calculated threshold voltage information Ss is stored in the threshold voltage storage unit 147.

  FIG. 5 is a flowchart for explaining the procedure of the processing operation in the calculation unit 42 of the LED drive device 101 according to the second embodiment.

  As shown in FIG. 5, the processing from step S11 to S14 is performed in the same manner as the processing from step S1 to S4 in the first embodiment. That is, the calculation unit 42 acquires the dimming rate information Sa from the dimming table storage unit 41 based on the dimming instruction signal Sad, and generates PWM signal generation information Sp corresponding to the acquired dimming rate information Sa as a PWM signal. To the unit 43.

  Here, in the second embodiment, only the process of step S13 is performed after the process of step S12. After the process of step S13, the processes of step S14 and step S15 are performed.

  In step S <b> 15, the computing unit 42 calculates threshold voltage information Ss based on the dimming rate information Sa acquired in step S <b> 13 and the dimming instruction signal Sad input to the control circuit unit 104. That is, the calculation unit 42 calculates a threshold voltage corresponding to the dimming instruction signal Sad. The calculation unit 42 stores the calculated threshold voltage information Ss in the threshold voltage storage unit 147. When storing the threshold voltage information Ss, the calculation unit 42 performs the process of step S16.

  In step S <b> 16, the calculation unit 42 updates the threshold voltage based on the threshold voltage information Ss stored in the threshold voltage storage unit 147. When the calculation unit 42 updates the threshold voltage, it performs the process of step S17.

  Steps S17 and S18 are performed in the same manner as steps S7 and S8 in the first embodiment. That is, the calculation unit 42 compares whether or not the detection voltage VL is larger than the threshold voltage, and outputs the error determination signal Sj to the error signal generation unit 46 if the detection voltage VL is larger. If the detection voltage VL is equal to or lower than the threshold voltage, the calculation unit 42 returns to the process of step S1.

  Also in the second embodiment, the threshold voltage corresponding to the dimming state is compared with the detection voltage VL, and the abnormal state of the LED module 10 is determined. Therefore, the same effect as the first embodiment can be obtained.

  [Others]

  In the above embodiment, when an abnormal state occurs in the LED module 10, the error signal Se is sent from the control circuit unit 4 (104) to the DC / DC converter 2, and the DC / DC converter 2 receives the error signal Se. And it demonstrated as a structure which stops the operation | movement which outputs drive electric power to the LED module 10. FIG. However, it is not always necessary to stop the operation of outputting drive power to the LED module 10 when an abnormal state occurs.

  For example, the DC / DC converter 2 may be configured to reduce the drive power sent to the LED module 10 when an abnormal state occurs in the LED module 10. In this case, when an abnormal state occurs in the LED module 10, the calculation unit 42 generates the PWM signal so that the PWM signal generation unit 43 generates the PWM dimming signal Sc that reduces the current flowing through the LED module 10. The information Sp is output to the PWM signal generation unit 43, and the PWM signal generation unit 43 sends the PWM dimming signal Sc for reducing the current flowing through the LED module 10 to the DC / DC converter 2. Thereby, the DC / DC converter 2 can reduce the drive power sent to the LED module 10 based on this PWM dimming signal Sc.

  Also, for example, when an abnormal state occurs in the LED module 10, whether to reduce the drive power sent to the LED module 10 or stop the operation of outputting the drive power to the LED module 10 depending on the occurrence state of the abnormal state , May be selected for processing. In this case, for example, when it is determined in step S7 of FIG. 3 that the detected voltage is greater than the threshold voltage, the calculation unit 42 flows to the LED module 10 in the PWM signal generation unit 43 according to the voltage difference. The PWM signal generation information Sp is output to the PWM signal generation unit 43 so that the PWM dimming signal Sc for reducing the current is generated, or the error signal generation unit 46 outputs the driving power to the LED module 10. It suffices to select whether to output the error determination signal Sj to the error signal generator 46 so that the error signal Se to be stopped is generated.

  You may comprise an LED drive device and a lighting fixture combining the characteristic point of the said embodiment suitably. For example, a threshold voltage storage unit may be provided together with the threshold voltage table storage unit.

  Each circuit of the LED driving device may be configured using circuit elements different from those of the above-described embodiment. For example, the current detection circuit is not limited to the one configured using only the resistor and the diode as described above.

  The number of LEDs constituting the LED unit may be one or more, and the number of LED units connected in parallel may be two or more. Further, the LED driving device is not limited to an LED module in which a plurality of LED units are connected in parallel, and various LED modules including one or a plurality of LEDs may be driven. Even in this case, the abnormal state occurring in the LED module can be appropriately detected according to the dimming state, and the drive control of the LED driving device can be appropriately and easily performed according to the abnormal state.

  In addition to the DC / DC converter, the current detection circuit, and the control circuit unit as described above, another circuit may be provided in the LED driving device. In the LED drive device, the configuration of the drive circuit unit that outputs drive power to the LED module is not limited to the DC power supply and the DC / DC converter. For example, an AC power source and an AC / DC converter may be used.

  In addition, the LED driving device according to the present invention is not limited to that used in a lighting fixture that illuminates a space. For example, the LED driving device according to the present invention may be used in a lighting fixture used as a backlight of various devices. In addition, the present invention can be applied to various devices such as an instrument that irradiates a light beam for a specific purpose using an LED and an instrument that displays and transmits information by the light from the LED itself.

  The processing in the above embodiment may be performed by software or by using a hardware circuit.

  A program for executing the processing in the above-described embodiment can be provided, or the program can be recorded on a recording medium such as a CD-ROM, a flexible disk, a hard disk, a ROM, a RAM, or a memory card and provided to the user. It may be. The program may be downloaded to the apparatus via a communication line such as the Internet. The processing described in the text based on the above flowchart is executed by a CPU or the like according to the program.

  The above embodiment should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1,101 LED drive device 2 DC / DC converter (an example of a drive circuit unit)
DESCRIPTION OF SYMBOLS 3 Current detection circuit 4,104 Control circuit part 10 LED module 10a, 10b LED unit 20 Dimming control apparatus 41 Dimming table memory | storage part 42 Calculation part (determination signal output part, dimming rate acquisition part, threshold voltage acquisition part, production | generation Example of information output unit, abnormality detection unit, threshold voltage calculation unit)
43 PWM signal generation unit 44 threshold voltage table storage unit 45 A-D conversion unit 46 error signal generation unit 100 luminaire 147 threshold voltage storage unit Sad dimming instruction signal Sa dimming rate information Ss threshold voltage information Sp PWM signal generation information Sc PWM dimming signal Sj error determination signal Se error signal Sf feedback signal VL detection voltage Vd (detection voltage) digital signal

Claims (6)

In accordance with the dimming instruction signal, the dimming operation of an LED (light emitting diode) module configured by connecting a plurality of LED units composed of one LED or two or more LEDs connected in series in parallel. An LED driving device to perform,
A drive circuit unit that outputs drive power to the LED module;
A current detection circuit that is connected to the LED module, detects a current flowing through the LED module, and outputs a detection voltage corresponding to a detection result;
Comparing the threshold voltage corresponding to the light control direction signal and the detection voltage output from the current detection circuit, and a control circuit unit for detecting an abnormal state of the LED module according to the comparison result,
The threshold voltage corresponds to a predetermined number of LED short detection counts or LED unit open detection counts in each of the plurality of dimming instruction signals,
The control circuit unit is
When the detection voltage is within a predetermined range in which the number of LED short detections or the number of open detections of the LED unit does not exceed the predetermined number, the abnormal state is not detected according to the comparison result,
An LED driving device that detects the abnormal state according to the comparison result when the detected voltage is an abnormal voltage that is not within the predetermined range . The control circuit unit is
A dimming table storage unit for storing dimming rate information corresponding to each of the plurality of dimming instruction signals in advance;
A threshold voltage table storage unit that stores information on threshold voltages corresponding to each of the plurality of dimming instruction signals in advance;
A dimming rate acquisition unit that acquires dimming rate information corresponding to the dimming instruction signal based on information stored in the dimming table storage unit;
A threshold voltage acquisition unit that acquires a threshold voltage corresponding to the dimming instruction signal based on information stored in the threshold voltage table storage unit;
A generation information output unit that outputs PWM signal generation information based on the dimming rate information acquired by the dimming rate acquisition unit;
A PWM signal generation unit that generates a PWM dimming signal based on the PWM signal generation information output by the generation information output unit, and outputs the generated PWM dimming signal to the drive circuit unit;
An abnormality detection unit that compares the threshold voltage acquired by the threshold voltage acquisition unit with the detection voltage input from the current detection circuit and detects an abnormal state of the LED module according to the comparison result. The LED driving device according to claim 1 . The control circuit unit is
A dimming table storage unit for storing dimming rate information corresponding to each of the plurality of dimming instruction signals in advance;
A dimming rate acquisition unit that acquires dimming rate information corresponding to the dimming instruction signal based on information stored in the dimming table storage unit;
A generation information output unit that outputs PWM signal generation information based on the dimming rate information acquired by the dimming rate acquisition unit;
A PWM signal generation unit that generates a PWM dimming signal based on the PWM signal generation information output by the generation information output unit, and outputs the generated PWM dimming signal to the drive circuit unit;
A threshold voltage calculator that calculates a threshold voltage corresponding to the dimming instruction signal based on the dimming ratio information acquired by the dimming ratio acquisition unit and the dimming instruction signal;
An abnormality detection unit that compares the threshold voltage calculated by the threshold voltage calculation unit with the detection voltage input from the current detection circuit and detects an abnormal state of the LED module according to the comparison result. The LED driving device according to claim 1 . The said control circuit part controls the said drive circuit part so that the electric power supply to the said LED module may be stopped or reduced, when detecting the abnormal state of the said LED module, The any one of Claim 1 to 3 LED drive device of description. The control circuit unit is
A determination signal output unit that outputs an error determination signal when an abnormal state of the LED module is detected by the abnormality detection unit;
The determination signal when said error determination signal from the output section is input, further comprising an error signal generator for outputting an error signal to the driving circuit unit, LED driving device according to claim 2 or 3. An LED module in which a plurality of LED units composed of one LED or two or more LEDs connected in series are connected in parallel;
The LED driving device according to any one of claims 1 to 5 , which drives the LED module;
A lighting fixture comprising: a dimming control device that outputs the dimming instruction signal to the LED driving device.

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