JP2014086363A - Led drive device, led drive method, and luminaire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and method for driving an LED, capable of performing a protective operation to an LED module driven by constant current, and a luminaire.SOLUTION: An LED drive device 1 includes: a DC/DC converter 2 outputting drive power to an LED module 10 by constant current control; a voltage detection section 45 detecting the working voltage of the LED module 10; and a control circuit section 4 comparing a detected voltage output from the voltage detection section 45 with a threshold voltage stored in a threshold voltage storage section 44 to detect an abnormality of the LED module 10, and performing a protective operation for the LED module 10 in which an abnormality is detected.

Description

  The present invention relates to an LED driving device, an LED driving method, and a lighting fixture. In particular, the present invention relates to an LED driving device, an LED driving method, and a lighting fixture for an LED module that performs constant current driving.

  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 driving device used for such lighting fixtures, when an abnormal state such as an abnormal current flows due to variations in the electrical characteristics of LEDs occurs, a device that performs drive control such as interruption of current in response thereto is generated. is there.

  Patent Document 1 below discloses a configuration of an LED driving device provided in a lighting fixture 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 driving device, when an abnormal current flows through any of the plurality of series connected bodies, the current of the series connected body through which the abnormal current flows is cut off. Moreover, in this LED drive device, 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 LED driving device of Patent Document 1 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 driving device, there is a problem in that an appropriate protection operation is not performed when constant current control is used in a power supply circuit that supplies power to the LED module.

  An LED is generally an element having a large individual difference due to manufacturing variations (variations in electrical characteristics, luminous flux, color, etc.). For this reason, in a lighting fixture that uses an LED module as a light source, constant current driving is performed to keep the current supplied to the LED module constant, and the characteristics of each LED are aligned so that the luminous flux, color, etc. are uniformly maintained. There is something that was made.

  In an LED module configured by connecting a plurality of LEDs connected in series to each other in parallel, a series connection including the LEDs when any LED is in an open state (electrical cutoff state). No current flows through the body. In the LED module using the constant current drive, when there is a series connection body in which the current stops flowing due to the opening of the LED, the amount of current that flows through the other series connection body increases. For example, when the LED module has a configuration in which two series connected serially connected two LEDs are connected in parallel, when the series of connected LEDs is opened and no current flows, the other serial connected Twice as much current as normal flows through the body. Such a current twice as large as that in the steady state is a kind of abnormal current.

  In the LED drive device of Patent Document 1, when an abnormal current flows in any of a plurality of series connected bodies, a protection operation is performed to cut off the current of the series connected body in which the abnormal current flows. However, when the above-described protection operation is applied to the LED module using the constant current drive, the amount of current flowing through the other series connection bodies is increased even by the operation of cutting off the current of the series connection bodies through which the abnormal current flows. . As a result, an excessive forward voltage is generated in the LEDs of the serial connection body in which no abnormality has occurred, which may cause a new failure.

  The present invention has been made to solve the above-described problem, and an object thereof is to provide an LED driving device and a lighting fixture that can perform an appropriate protection operation on an LED module that performs constant current driving. .

  An exemplary LED driving device of the present invention performs dimming operation of an LED module configured by connecting a series connection body in which one or more LEDs are connected in series in parallel in accordance with a dimming instruction signal. An LED driving device for performing a driving circuit that outputs driving power by constant current control for supplying a constant current to the LED module, a voltage detecting unit that detects an operating voltage of the LED module, and The detection voltage output from the voltage detection unit is compared with a preset threshold voltage, and when the detection voltage exceeds the threshold voltage, an abnormal state of the LED module is detected, and the abnormal state is detected. And a control circuit unit that performs a protection operation of the LED module.

  The LED driving device of the present invention is based on the above-described configuration, and can take various forms as follows, for example.

  That is, in the exemplary LED driving device of the present invention, the control circuit unit stores a threshold voltage that stores information on a threshold voltage set corresponding to an operating voltage when the LED module is driven at the maximum dimming stage. A storage unit; and an abnormality detection unit that detects the abnormal state of the LED module by comparing the threshold voltage stored in the threshold voltage storage unit with the detection voltage input from the voltage detection unit. Is preferred.

  In addition, the exemplary LED driving method of the present invention is a constant LED that supplies a constant current to an LED module configured by connecting a series connection body in which one or more LEDs are connected in series to each other in parallel. An LED driving method for driving by current control, wherein a detection voltage obtained by detecting an operating voltage of the LED module is compared with a preset threshold voltage, and the detection voltage exceeds the threshold voltage An abnormality determination step of determining an abnormal state of the LED module, and a protection step of performing a protection operation of the LED module in which the abnormal state is detected by the abnormality determination step.

  In the exemplary LED driving method of the present invention, the LED module can perform a dimming operation according to a dimming instruction signal. In the abnormality determination step, the LED module is set to a maximum dimming stage. It is preferable that the abnormal state of the LED module is determined by comparing the detection voltage with a threshold voltage set corresponding to the operating voltage when driving with.

  An exemplary lighting fixture of the present invention includes an LED module in which a plurality of LED units each having one or more LEDs connected in series are connected in parallel, and the LED driving device described above that drives the LED module; A dimming control device that outputs the dimming instruction signal to the LED driving device.

  In the present invention, it is possible to detect an abnormality caused by the opening of the LED in the LED module that performs constant current driving, and to perform an appropriate protection operation.

It is a block diagram which shows the structure of the lighting fixture using the LED drive device which concerns on embodiment of this invention. It is a block diagram which shows the structure of the LED drive device and LED module which concern on Embodiment 1. FIG. It is a flowchart which shows the procedure of the processing operation in the calculating part of the LED drive device of FIG.

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

  FIG. 1 is a block diagram showing a configuration of a lighting fixture 100 using an LED driving device according to an embodiment of the present invention.

  The lighting fixture 100 includes an LED driving device 1, an LED module 10, and a dimming control device 20. The luminaire 100 is configured as a luminaire 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 lighting fixture 100, the brightness of the 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 connected to 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.

  In the present 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 unit 10a and the LED unit 10b may be mounted on the same substrate, or may be mounted on different substrates. That is, the “unit” described in the present specification is not limited to a configuration in which the “unit” is mounted on different substrates.

  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 and a control circuit unit 4. The LED module 10 is connected to the DC / DC converter 2. 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 (see FIG. 1).

  The DC / DC converter 2 is connected to a direct current power source Vcc. The DC / DC converter 2 outputs a drive current to the LED module 10. Here, the drive current output from the DC / DC converter 2 to the LED module 10 is a constant current corresponding to the dimming stage. That is, the DC power supply Vcc and the DC / DC converter 2 are power supply circuits that control the LED module 10 with constant current. The DC power source Vcc can supply an AC current supplied from an AC commercial power source and converted from AC to DC by an AC / DC converter (not shown).

  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 (drive current) 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 an open LED is generated in either or both of the LED unit 10a and the LED unit 10b. 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.

  A resistor R1 is connected to the cathode side terminal of the LED unit 10a. A resistor R2 is 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 connection portion of the resistors R1 and R2 is connected to the ground potential via the resistor R0 and is also 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.

  Here, for example, consider a configuration in which the LED module 10 has LED units of 8 lines in parallel, and a current of 100 mA flows per line (per LED unit). In this case, in the constant current control, a total current of 800 mA is supplied through 8 lines, and an equal value of voltage is generated in each line. When the LED included in the LED module 10 is not abnormal (open state), the currents Ia to Ih are all equal to 100 mA, and the voltages generated in the respective lines are equal.

  When an LED opens in one line of a plurality of lines and the current stops flowing, the value of the current flowing in the other 7 lines increases to about 114 mA by constant current control, and the operating voltage in the other 7 lines Also rises. That is, the operating voltages in the other seven lines increase at the same rate as the current increase rate. In the LED module 10 having the LED units of 8 lines in parallel, when one line is in an open state, the operating voltage rises by about 15% compared to the normal time when no open occurs. Further, when the two lines are in an open state, the operating voltage increases by about 30% with respect to the normal time.

  The control circuit unit 4 is a microcomputer, for example. The control circuit unit 4 detects the voltage (Vin, Vout) across the LED module 10. The control circuit unit 4 compares the voltage across the LED module 10 with the 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 that is the voltage across the LED module 10 is an abnormal voltage that is not within a predetermined range. Specifically, when the operating voltage of the LED module 10 exceeds the predetermined value and becomes an overvoltage, it is detected that the LED has been opened. These operations are performed in the control circuit unit 4 when the control circuit unit 4 executes a predetermined control program, for example. The voltage Vin is a voltage on the input side of the LED module 10 (the anode side of the LED included in the LED module 10). The voltage Vout is a voltage on the output side of the LED module 10 (the cathode side of the LED included in the LED module 10).

  As shown in FIG. 2, the control circuit unit 4 includes a dimming table storage unit 41, a calculation unit (an example of an abnormality detection unit) 42, a PWM signal generation unit 43, a threshold voltage storage unit 44, and a voltage detection. Part 45 and an error signal generation part 46.

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

  The dimming table storage unit 41 stores in advance dimming rate information Sa corresponding to each of the plurality of dimming instruction signals Sad. 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 can be handled by the LED drive device 1 is, for example, 20 steps.

  The threshold voltage storage unit 44 stores information on threshold voltage (threshold voltage information) Ss. The threshold voltage information Ss is, for example, a digital signal. The threshold voltage information Ss is set in advance corresponding to the operating voltage when the LED module 10 is driven at the maximum dimming stage. The threshold voltage information Ss is set according to, for example, the specifications of the LED module 10 to be driven by the LED driving device 1 (the number of LED units 10a, 10b,..., The number of LEDs used in each unit, etc.). Or the operating voltage of a specific unit among a plurality of LED units can be monitored and calculated.

  Here, the threshold voltage information Ss is set corresponding to the operating voltage when the LED module 10 is driven at the maximum dimming stage for the following reason. That is, the luminaire 100 according to the present embodiment can perform the dimming operation of the LED module 10, and the operating voltage of the LED module 10 is maximized when driven at the maximum dimming stage. On the other hand, when the LED module 10 is driven at a dimming level lower than the maximum dimming level, the operating voltage itself of the LED module 10 is lowered. Therefore, in this case, even if the LED is opened in the LED module 10 and the operating voltage is increased by this, it is considered that the protection operation does not reach the required level. For this reason, if the threshold voltage information Ss is set corresponding to the operating voltage when the LED module 10 is driven at the maximum dimming stage, it is possible to provide a minimum protection function against the overvoltage of the LED module. Can do.

  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 adjusts the drive current based on the output PWM dimming signal Sc, and drives the LED module 10. 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 voltage detection unit 45 is connected between the DC / DC converter 2 and the LED module 10 and can detect the voltage Vin on the input side of the LED module 10. The voltage detection unit 45 is connected between the LED module 10 and the resistors R1 and R2, and can detect the voltage Vout on the output side of the LED module 10. The voltage detection unit 45 can detect the higher voltage between the output side of the LED unit 10a and the output side of the LED unit 10b. The voltage detection unit 45 is connected to the calculation unit 42. The voltage detector 45 converts the detected voltage value (detected voltage) into, for example, a digital signal Vd. The converted digital signal Vd is sent to the calculation unit 42. It is preferable that the voltage detector 45 detects the operating voltage of the LED module 10 at regular intervals. Since the abnormal voltage in the LED module 10 can be detected earlier as the fixed time is shorter, the LED module 10 can be protected from overvoltage more quickly. The voltage detection unit 45 may be configured to sequentially send the detected operating voltage of the LED module 10 to the calculation unit 42, store the detected operating voltage of the LED module 10 inside, and receive a request from the calculation unit 42. It is good also as a structure sent to the calculating part 42 only at the time. The voltage value may be sent to the calculation unit 42 as an analog signal.

  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.

  That is, 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. 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. Thus, the generated PWM signal generation information Sp is output to the PWM signal generation unit 43.

  In addition, the calculation unit 42 acquires threshold voltage information Ss stored in the threshold voltage storage unit 44, that is, a digital signal corresponding to the threshold voltage. Then, the calculation unit 42 compares the acquired digital signal with the digital signal Vd corresponding to the detection voltage input from the voltage detection unit 45. 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.

  The operation of the arithmetic unit 42 as described above is executed as follows by, for example, the arithmetic unit 42 executing a control program stored therein.

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

  In step S1, 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 S6.

  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 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 dimming 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 storage unit 44 and obtains threshold voltage information Ss. 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 receives the digital signal Vd corresponding to the detected voltage. It is compared whether or not it is larger than the digital signal corresponding to the threshold voltage information Ss. That is, the calculation unit 42 compares the detection voltage with the threshold voltage based on the threshold voltage information Ss read from the threshold voltage storage unit 44, and determines whether the detection voltage is greater than the threshold voltage. If the calculation unit 42 determines that the detected voltage is greater than the threshold voltage (YES), it performs the process of step S7. When the calculation unit 42 determines that the detected voltage is equal to or lower than the threshold voltage (NO), the calculation unit 42 returns to the process of step S1. In addition, it is preferable to perform the determination process shown in step S6 at regular intervals. The determination process shown in step S6 corresponds to an abnormality determination step in the present invention.

  In step S <b> 7, the calculation unit 42 outputs the error determination signal Sj to the error signal generation unit 46. When the calculation unit 42 outputs the error determination signal Sj, the processing operation ends.

  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. In the present embodiment, the processing unit 42 outputs the error determination signal Sj, the error signal generation unit 46 outputs the error signal Se, and the DC / DC converter 2 supplies power to the LED module 10. The protection process of the present invention is constituted by the stopping process.

  Note that step S6 is preferably performed a plurality of times in a short cycle. Thereby, the protection performance with respect to the overvoltage in the LED module 10 can be improved. For example, if the execution timing of step S6 is set to a long cycle, it may take time until an abnormal voltage is detected after the open state of the LED in the LED module 10 occurs. In this case, an overvoltage for a relatively long time is applied to the normal LED unit, and the normal LED unit may fail due to the overvoltage. On the other hand, by setting the execution timing of step S6 to a short cycle, it is possible to shorten the time from when the open state occurs in the LED in the LED module 10 until the abnormal voltage is detected. According to this, since it is possible to shorten the time over which the normal LED unit takes overvoltage, it is possible to protect the normal LED unit from failure due to overvoltage.

  As described above, in the present embodiment, the abnormal state due to the opening of the LED of the LED module controlled at constant current can be determined from the comparison result of the threshold voltage and the detection voltage, and the corresponding control operation is appropriately performed. It can be carried out.

  In the present embodiment, PWM control is performed, but current phase control or the like may be used.

  Further, in the present embodiment, one DC / DC converter 2 is provided for a plurality of LED units, but may be provided for each of the plurality of LED units.

  According to the above embodiment, it is possible to appropriately detect circuit open in the LED module, and thus it is possible to prevent the element temperature in the LED module from rising to an abnormal value. Moreover, it can prevent that the temperature which a lighting fixture emits rises to an abnormal value by mounting the LED drive device in this Embodiment in a lighting fixture.

  Since the threshold voltage information Ss in the above embodiment can be arbitrarily set, the number of open detections of the LED unit can be determined and the operation of the LED module can be stopped based on the number. For example, if the LED module has three or more LED units, it will not be detected even if one of the LED units is open, and two or more of the LED units will be open. This can be detected and the driving of the LED module can be stopped.

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

  In the above-described embodiment, the description has been given of the configuration in which the driving of the LED module is stopped when an abnormal state occurs in the LED module. However, the configuration is not necessarily limited to stopping the driving of the LED module when an abnormal state occurs.

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

  Also, for example, when an abnormal state occurs in the LED module, depending on the state of occurrence of the abnormal state, it is possible to select and process whether to reduce the driving power sent to the LED module or to stop the operation of the LED module It may be. In this case, for example, when it is determined in step S6 of FIG. 3 that the detected voltage is larger than the threshold voltage, the calculation unit 42 reduces the drive power sent to the LED module according to the voltage difference, It suffices to select whether to stop the operation of the LED module. That is, when reducing the drive power sent to the LED module, 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. The information Sp is output to the PWM signal generator 43. When stopping the operation of the LED module, the calculation unit 42 generates an error determination signal Sj so that the error signal generation unit 46 generates an error signal Se for stopping the operation of outputting drive power to the LED module. The signal is output to the signal generator 46.

  Each circuit of the LED driving device may be configured using circuit elements different from those of the above-described embodiment.

  In addition to the DC / DC converter 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. For example, in each of the embodiments described above, the detection voltage and the threshold voltage are compared by software. However, for example, the detection voltage and the threshold voltage may be compared using a hardware circuit such as an operational amplifier. Good.

  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 present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 LED drive device 2 DC / DC converter (an example of a drive circuit part)
4 control circuit unit 10 LED module 10a, 10b LED unit 20 dimming control device 41 dimming table storage unit 42 calculation unit (an example of abnormality detection unit)
43 PWM signal generation unit 44 threshold voltage storage unit 45 voltage detection unit 46 error signal generation unit 100 lighting fixture 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 Vd (detection voltage) digital signal

Claims (5)

In accordance with a dimming instruction signal, an LED driving device that performs a dimming operation of an LED module configured by connecting a series connection body in which one or more LEDs are connected in series to each other in parallel.
A driving circuit unit that outputs driving power by constant current control for supplying a constant current to the LED module;
A voltage detector for detecting an operating voltage of the LED module;
The detection voltage output from the voltage detection unit is compared with a preset threshold voltage, and when the detection voltage exceeds the threshold voltage, an abnormal state of the LED module is detected, and an abnormal state is detected. An LED driving device comprising: a control circuit unit that performs a protection operation of the LED module. The LED driving device according to claim 1,
The control circuit unit is
A threshold voltage storage unit that stores information on a threshold voltage set corresponding to an operating voltage when driving the LED module at the maximum dimming stage;
An LED drive device comprising: an abnormality detection unit that detects an abnormal state of the LED module by comparing the threshold voltage stored in the threshold voltage storage unit with the detection voltage input from the voltage detection unit. An LED driving method of driving by constant current control for supplying a constant current to an LED module configured by connecting a series connection body in which one or more LEDs are connected in series to each other in parallel.
An abnormality determination that compares a detection voltage obtained by detecting the operating voltage of the LED module with a preset threshold voltage and determines an abnormal state of the LED module when the detection voltage exceeds the threshold voltage Process,
A protection step of performing a protection operation of the LED module in which an abnormal state is detected by the abnormality determination step. The LED driving method according to claim 3,
The LED module can perform a dimming operation according to a dimming instruction signal,
In the abnormality determination step, a threshold voltage set corresponding to an operating voltage when the LED module is driven at the maximum dimming stage is compared with the detection voltage to determine an abnormal state of the LED module. LED driving method. An LED module in which a plurality of LED units each having one or more LEDs connected in series are connected in parallel;
The LED driving device according to any one of claims 1 and 2, 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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