JP5364897B2 - Power supply device and lighting fixture - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply, which supplies proper power and ensure stable operation, and to provide a luminaire. <P>SOLUTION: The power supply includes a constant current signal generator 22, which generates a constant current control signal, based on a current flowing to a light emitting diode 18, and a constant voltage control signal generator 24, which generates a constant voltage control signal, based on a voltage applied to the light emitting diode 18. Usually, it makes a constant current control to a light emitting diode 18, based on a constant current control signal generated in a constant current control signal generator 22, and when the voltage applied to the light emitting diode 18 reaches a specified value by load abnormality, it makes a constant voltage control to the light emitting diode 18, based on a constant voltage control signal generated in a constant voltage control signal generator 24 from this point of time. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a power supply device and a lighting fixture that are optimal for driving a semiconductor light emitting element such as a light emitting diode.

  Recently, as a power source for a semiconductor light emitting element such as a light emitting diode, a DC power source device using a switching means is often used.

And as this kind of power supply device, as disclosed in Patent Document 1, the load current flowing through the load is detected, and the switching element is turned on and off by the control circuit based on this detection signal to control the output to the load. There is something.
JP 2001-313423 A

  However, in Patent Document 1, for example, a light emitting diode is used as a load, and a constant current is controlled so that the current flowing through the light emitting diode is constant and the light emitting diode has constant brightness. When a voltage higher than a predetermined value, that is, an overvoltage, is applied to the light emitting diode, the light emitting diode suddenly generates heat and may be damaged although it maintains a constant brightness.

  Therefore, conventionally, an overvoltage detection means for detecting an overvoltage applied to the light emitting diode is provided, for example, as shown in FIG. 6, from the state where the current flowing through the light emitting diode is controlled at a constant value Ic, When the overvoltage detection means detects an overvoltage Vo (point A in the figure) applied to the light emitting diode due to a load abnormality, it is considered to cancel the constant current control and forcibly turn off the light emitting diode.

  However, when performing constant current control to control the current flowing through the light emitting diode to a constant level, the guaranteed operating range of the power supply device is usually considered in advance by taking into account variations in the forward voltage of the light emitting diode and variations due to temperature characteristics depending on the usage environment. In order to set a wide (design range), a so-called surplus design has been performed, such as setting an overvoltage Vo determined as a load abnormality to a large value. As a result, inappropriate power continues to enter the light emitting diode due to the overvoltage at this time until the overvoltage detecting means detects the overvoltage Vo due to the load abnormality. In this case, the light emitting diode may generate abnormal heat. .

  This invention is made | formed in view of the said situation, and it aims at providing the power supply device and lighting fixture which can supply appropriate electric power and can ensure the stable operation | movement.

According to a first aspect of the present invention, there is provided a semiconductor light emitting element; constant current control signal generating means for generating a constant current control signal based on a current flowing through the semiconductor light emitting element; and a constant current control signal generating means based on a voltage applied to the semiconductor light emitting element. Constant voltage control signal generating means for generating a voltage control signal; current detecting means for detecting whether the current flowing through the semiconductor light emitting element is a minimum current that guarantees an allowable brightness for the semiconductor light emitting element ; ; wherein performs constant current control with respect to the semiconductor light emitting element based on the constant current control signal generated by the constant current control signal generating means, the voltage applied to the semiconductor light-emitting device reaches a predetermined value the voltage control signal based on the constant voltage control signal generated by the generating means have rows constant voltage control for the semiconductor light emitting element, current flowing through the semiconductor light emitting element the minimum current If that is which was detected by said current detecting means, said control means cancels the constant-voltage control to turn off the semiconductor light-emitting device; and characterized by including the.

According to a second aspect of the invention, a power supply device according to claim 1 Symbol placement; a lighting fixture which is characterized by comprising a; an instrument body having the power supply device.

  ADVANTAGE OF THE INVENTION According to this invention, appropriate electric power can be supplied with respect to a semiconductor light-emitting device, and the stable operation | movement which does not produce malfunctions, such as a semiconductor light-emitting device being damaged with a heat | fever, can be ensured.

  Moreover, according to this invention, the lighting fixture which can supply appropriate electric power and can ensure the stable operation | movement can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
First, the lighting fixture to which the present invention is applied will be briefly described.

  1 (a), (b), and (c), reference numeral 1 denotes an instrument body, and the instrument body 1 has a rectangular shape, and is provided with a mounting bracket 2 at one end. It can be attached to a support column. Moreover, the instrument main body 1 has a top plate 1a that constitutes a part of the casing, and a power supply unit substrate 3 and a constant current circuit substrate 4 are arranged side by side on the inner surface side of the top plate 1a. Here, the casing having the top plate 1a is made of a material having high thermal conductivity, and may be made of a metal having high thermal conductivity, for example, or has a thermal conductivity that can expect a heat radiation effect. If it is, it may be made of resin. A power supply device 100 is provided on the power supply unit substrate 3. The power supply device 100 will be described later.

  Moreover, as shown in FIG.1 (c), as for the instrument main body 1, the protrusion part 1b of a cross-section reverse triangle shape is formed along the longitudinal direction of the top plate 1a, and an LED module is along the inclined side surface of this protrusion part 1b. 5 is provided. The LED module 5 has a base portion 5a having a triangular wave section, and the base portion 5a having a triangular wave cross section is disposed along the side surface of the protruding portion 1b. In the LED module 5, light emitting diode groups each including a plurality (four in the illustrated example) of light emitting diodes (LEDs) 6 are arranged in each valley portion of the triangular wave base 5a. In this case, the side surfaces of the crests on both sides of the valley where the light emitting diode group is arranged are formed on reflecting surfaces that reflect the light emitted from the light emitting diodes 6.

  FIG. 2 shows a schematic configuration of the power supply apparatus 100 provided on the power supply unit substrate 3 of the lighting fixture thus configured.

  In FIG. 2, 11 is an AC power source, and this AC power source 11 is a commercial power source (not shown). The AC power supply 11 is connected to an input terminal of a full-wave rectifier circuit 12. The full wave rectification circuit 12 generates an output obtained by full wave rectification of the AC power from the AC power supply 11. A smoothing capacitor 13 is connected between the positive and negative output terminals of the full-wave rectifier circuit 12 and constitutes a DC power source together with the full-wave rectifier circuit 12.

  Here, a DC power supply obtained by rectifying and smoothing a commercial power supply is used, but a power factor improving converter for improving the power factor may be used.

  A DC-DC converter 10 is connected to the capacitor 13. The DC-DC converter 10 includes a switching transformer 14 that is a flyback transformer, a switching transistor 15 as switching means, a diode 16 as rectifying and smoothing means, and a smoothing capacitor 17. Here, a series circuit of the primary winding 14 a of the switching transformer 14 and the switching transistor 15 is connected to both ends of the capacitor 13. The switching transformer 14 has a secondary winding 14b magnetically coupled to the primary winding 14a. The secondary winding 14b of the switching transformer 14 is connected to a rectifying / smoothing circuit including a diode 16 and a smoothing capacitor 17 having the polarities shown in the figure. This rectifying / smoothing circuit constitutes a DC output generating means together with the switching transistor 15 and the switching transformer 14, rectifies the AC output generated from the secondary winding 14 b of the switching transformer 14 by the diode 16, and converts this rectified output to the smoothing capacitor 17. To generate a direct current output.

  Here, a flyback converter is used as the DC-DC converter 10. For example, when the voltage on the load side is lower than the power supply voltage, the step-down converter is used. When the voltage on the load side is higher than the power supply voltage, the step-up converter is used. A buck-boost converter may be used. The point is that the output can be varied according to the state of the load or an external signal.

  At both ends of the smoothing capacitor 17 constituting the rectifying and smoothing circuit of the DC-DC converter 10, a light-emitting diode 18 (corresponding to the light-emitting diode (LED) 6 described in FIG. 1) as a light source as a light source is provided as a load. Is connected.

  A current detection unit 19 is connected in series to the light emitting diode 18 as current detection means. The current detector 19 uses a resistor 191 as an impedance element. The light emitting diode 18 is connected in parallel with a voltage detection unit 20 as voltage detection means. The voltage detection unit 20 uses a series circuit of resistors 201 and 202 as an impedance element.

  The current detector 19 is connected to a constant current control signal generator 22 as a constant current control signal generator and a low current detector 29 as a low current detector.

  The constant current control signal generation unit 22 includes a comparator 221 that is a comparison unit. A connection point between the resistor 191 of the current detector 19 and the light emitting diode 18 is connected to one input terminal of the comparator 221, and a reference signal source 23 is connected to the other input terminal. The reference signal source 23 is set with a predetermined reference signal for controlling the current flowing through the light emitting diode 18 to be constant. The output terminal of the comparator 221 is connected to the output switching unit 27. The output switching unit 27 will be described later.

  The low current detection unit 29 includes a comparator 291 that is a comparison unit. A connection point between the resistor 191 of the current detector 19 and the light emitting diode 18 is connected to one input terminal of the comparator 291, and a reference signal source 30 is connected to the other input terminal. The reference signal source 30 is set with a reference signal for detecting a minimum current that guarantees an allowable brightness for the light emitting diode 18. The output terminal of the comparator 291 is connected to the output switching unit 27.

  A constant voltage control signal generator 24 as a constant voltage control signal generator is connected to the voltage detector 20. The constant voltage control signal generation unit 24 includes a comparator 241 that is a comparison unit. A connection point between the resistors 201 and 202 of the voltage detection unit 20 is connected to one input terminal of the comparator 241, and a reference signal source 25 is connected to the other input terminal. The reference signal source 25 is set with a predetermined reference signal for controlling the voltage applied to the light emitting diode 18 to be constant. The output terminal of the comparator 241 is connected to the output switching unit 27.

  The output switching unit 27 has an output terminal connected to the control circuit 26. The output switching unit 27 outputs the output of the constant current control signal generation unit 22 and the output of the constant voltage control signal generation unit 24 to the control circuit 26, and while the output of the constant current control signal generation unit 22 is generated. When the generation of the output from the low current detection unit 29 is stopped and the output from the constant voltage control signal generation unit 24 is generated instead of the output from the constant current control signal generation unit 22, the output of the low current detection unit 29 is controlled. It outputs to the circuit 26. The control circuit 26 is driven by a power supply unit (not shown), and the switching transistor 15 is turned on and off by its operation to drive the switching transformer 14.

  In this case, the control circuit 26 switches the switching transistor based on the comparison result (constant current control signal) between the output of the current detector 19 of the comparator 221 and the reference value of the reference signal source 23 in the constant current control signal generator 22. 15 is turned on / off, and constant current control is performed to control the current supplied to the light emitting diode 18 at a constant level. The output of the voltage detector 20 of the comparator 241 in the constant voltage control signal generator 24 and the reference value of the reference signal source 25 Based on the comparison result (constant voltage control signal), the switching transistor 15 is turned on / off, and constant voltage control is performed to control the output voltage applied to the light emitting diode 18 to be constant. The control circuit 26 performs constant current control with priority given to the output (constant current control signal) from the comparator 221 of the constant current control signal generation unit 22, and a voltage applied to the light emitting diode 18 due to a load abnormality is predetermined. When the value (reference value of the reference signal source 25) is reached, the output (constant voltage control signal) of the constant voltage control signal generator 24 at this time is received, and thereafter the comparator 241 of the constant voltage control signal generator 24 is received. The constant voltage control is performed with priority given to the output (constant voltage control signal). Further, when the output from the constant voltage control signal generation unit 24 is generated instead of the output from the constant current control signal generation unit 22, the control circuit 26 outputs from the low current detection unit 29 output from the output switching unit 27 from this time point. When the output is monitored and the comparator 291 detects that the output of the current detection unit 19 and the reference value of the reference signal source 30 match, this detection signal stops the on / off operation of the switching transistor 15 and cancels the constant voltage control. Then, the light emitting diode 18 is turned off.

  Next, the operation of the embodiment configured as described above will be described.

  In FIG. 2, when AC power from the AC power supply 11 is applied to the full-wave rectification circuit 12, the full-wave rectification circuit 12 performs full-wave rectification and supplies the smoothing capacitor 13 to the switching transformer 14 and the switching transistor 15.

  In this state, the switching transformer 14 is switched and driven by turning on and off the switching transistor 15 by the control circuit 26. In this case, when the switching transistor 15 is turned on, current is passed through the primary winding 14a of the switching transformer 14 to store energy, and when the switching transistor 15 is turned off, energy stored in the primary winding 14a is discharged through the secondary winding 14b. To do. As a result, a DC output is generated from both ends of the smoothing capacitor 17 constituting the rectifying and smoothing circuit, and this DC output is supplied to the light emitting diode 18.

  In this state, the control circuit 26 is switched by the constant current control signal generated from the comparison result between the output of the current detection unit 19 in the comparator 221 of the constant current control signal generation unit 22 and the reference value of the reference signal source 23. The transistor 15 is turned on / off to perform constant current control on the light emitting diode 18. 3 indicates this state, and a constant current Ic1 is supplied to the light-emitting diode 18. In this case, the output switching unit 27 stops generating the output from the low current detecting unit 29 while the output of the constant current control signal generating unit 22 is generated.

  From this state, when the voltage applied to the light emitting diode 18 reaches a predetermined value (point B shown in FIG. 3) due to a load abnormality or the like, the control circuit 26 outputs the constant voltage control signal generator 24 at this time (constant voltage). Thereafter, the output from the comparator 241 (constant voltage control signal) of the constant voltage control signal generator 24 is prioritized by the voltage control signal) to perform constant voltage control on the light emitting diode 18. 3 shows this state, and a constant voltage Vc1 is applied to the light emitting diode 18. FIG.

  When an output is generated from the constant voltage control signal generation unit 24, an output from the low current detection unit 29 is generated from the output switching unit 27 and is input to the control circuit 26. In this state, the control circuit 26 monitors the output from the comparator 291 of the low current detection unit 29. When the comparator 291 of the low current detector 29 matches the output of the current detector 19 and the reference value of the reference signal source 30 (point C shown in FIG. 3), the control circuit 26 uses the detection signal to cause the switching transistor 15 to switch. The on / off operation is stopped, the constant voltage control is canceled, and the light emitting diode 18 is turned off. Here, Ic2 shown in FIG. 3 is the brightness that is allowed for the light emitting diode 18 when the output of the current detector 19 and the reference value of the reference signal source 30 match in the comparator 291 of the low current detector 29. Guarantees the minimum current.

  Therefore, in this way, the constant current control signal generator 22 that generates a constant current control signal based on the current flowing through the light emitting diode 18 and the constant voltage control signal are generated based on the voltage applied to the light emitting diode 18. A constant voltage control signal generation unit 24 is provided, and constant current control is performed on the light emitting diode 18 based on the constant current control signal generated by the constant current control signal generation unit 22 and is applied to the light emitting diode 18 due to a load abnormality. When the voltage reaches a predetermined value, the constant voltage control for the light emitting diode 18 is performed based on the constant voltage control signal generated by the constant voltage control signal generation unit 24 from this point. As a result, even if the applied voltage of the light emitting diode 18 increases due to a load abnormality or the like, the control for the light emitting diode 18 is immediately shifted to the constant voltage control, so that the current for the conventional light emitting diode 18 is controlled to be constant. Compared with the case where excess power continues to enter the light emitting diode until an overvoltage is detected in the state, it is possible to supply appropriate power to the light emitting diode 18. As a result, it is possible to reliably prevent the light emitting diode from abnormally generating heat due to excess power and damaging the light emitting diode due to this heat, and to always ensure stable operation.

  In this case, since the brightness of the light emitting diode 18 may be slightly changed due to the shift from the constant current control to the constant voltage control, when the current decreases to a level where the brightness of the light emitting diode 18 cannot be guaranteed. Since the constant voltage control is canceled and the light emitting diode 18 is turned off, the light emitting diode 18 does not continue to be lit in an unstable state, and can always be lit in a stable range.

(Second Embodiment)
FIG. 4 shows a schematic configuration of a power supply device according to the second embodiment of the present invention. The same parts as those in FIG.

  In this case, a constant power control signal generator 42 is connected to the current detector 19 as a constant power control signal generator. The constant power control signal generation unit 42 includes a multiplier 421 and a comparator 422. The multiplier 421 has one input terminal connected to the connection point between the resistor 191 of the current detection unit 19 and the light-emitting diode 18, and the other input terminal connected to the connection point between the resistors 201 and 202 of the voltage detection unit 20. An output (power amount) obtained by multiplying the outputs of the detection unit 19 and the voltage detection unit 20 is generated. The comparator 422 has one input terminal connected to the output terminal of the multiplier 421 and the other input terminal connected to the reference signal source 43. The reference signal source 43 is set with a reference signal for controlling the power input to the light emitting diode 18 to be constant. The output terminal of the comparator 422 is connected to the control circuit 26 and also to the output switching unit 49. The output switching unit 49 is connected to the output terminal of the comparator 221 of the constant power control signal generation unit 22. The output switching unit 49 will be described later.

  A low current detector 47 is connected to the current detector 19 as a low current detector. The voltage detector 20 is connected to a low voltage detector 45 as a low voltage detector.

  The low current detection unit 47 includes a comparator 471 which is a comparison unit. The comparator 471 has one input terminal connected to a connection point between the resistor 191 of the current detection unit 19 and the light emitting diode 18, and the other input terminal connected to a reference signal source 48. The reference signal source 48 is set with a reference signal for detecting a minimum current that guarantees an allowable brightness for the light emitting diode 18. Moreover, the low voltage detection part 45 has the comparator 451 which is a comparison means. The connection point of the resistors 201 and 202 of the voltage detection unit 20 is connected to one input terminal of the comparator 451, and the reference signal source 46 is connected to the other input terminal. The reference signal source 46 is set with a reference signal for detecting a minimum voltage that guarantees an allowable brightness for the light emitting diode 18.

  Output terminals of the comparator 471 of the low current detection unit 47 and the comparator 451 of the low voltage detection unit 45 are connected to the output switching unit 49. While the output is generated from the constant power control signal generation unit 22, the output switching unit 49 stops generating the outputs from the low current detection unit 47 and the low voltage detection unit 45, and the constant power control signal generation unit 42. Output from the low current detector 47 and the low voltage detector 45 to the control circuit 26.

  The control circuit 26 turns the switching transistor 15 on and off based on the comparison result (constant current control signal) between the output of the current detector 19 of the comparator 221 and the reference value of the reference signal source 23 in the constant current control signal generator 22. Constant current control is performed to operate and control the current supplied to the light emitting diode 18 to be constant, and the comparison result between the output of the multiplier 421 of the comparator 422 and the reference value of the reference signal source 43 in the constant power control signal generator 42. Based on the (constant power control signal), the switching transistor 15 is turned on and off to perform constant power control for controlling the power input to the light emitting diode 18 to be constant. In addition, the control circuit 26 performs constant current control by giving priority to the output (constant current control signal) from the comparator 221 of the constant current control signal generator 22, and the power supplied to the light emitting diode 18 due to load abnormality is predetermined. When the value (reference value of the reference signal source 43) is reached, the output (constant power control signal) of the constant power control signal generation unit 42 at this time is received, and thereafter, the comparator 422 of the constant power control signal generation unit 42. The constant power control is performed with priority given to the output (constant power control signal). Further, when an output is generated from the constant power control signal generation unit 42, the control circuit 26 monitors the outputs of the low current detection unit 47 and the low voltage detection unit 45 output from the output switching unit 49 from this time point, The comparator 471 of the low current detector 47 matches the output of the current detector 19 with the reference value of the reference signal source 48, or the comparator 451 of the low voltage detector 45 outputs the output of the voltage detector 20 and the reference signal source 46. When it is detected that the reference value matches, the on / off operation of the switching transistor 15 is stopped, the constant power control is canceled, and the light emitting diode 18 is turned off.

  Others are the same as FIG.

  Even in such a configuration, the control circuit 26 generates the constant current control generated from the comparison result between the output of the current detection unit 19 of the comparator 221 and the reference value of the reference signal source 23 in the constant current control signal generation unit 22. The switching transistor 15 is turned on / off by a signal to perform constant current control on the light emitting diode 18. 5 indicates this state, and a constant current Ic3 is supplied to the light emitting diode 18. In this case, the output switching unit 49 stops generating the outputs of the low current detection unit 47 and the low voltage detection unit 45 while the output is generated from the constant power control signal generation unit 22.

  From this state, when the voltage applied to the light emitting diode 18 reaches a predetermined value (point D shown in FIG. 5) due to a load abnormality, the control circuit 26 outputs the output (constant power) of the constant power control signal generation unit 42 at this time. Thereafter, the output from the comparator 422 (constant power control signal) of the constant power control signal generator 42 is prioritized by the control signal), and the constant power control is performed on the light emitting diode 18. B2 in FIG. 5 shows this state, and constant power is supplied to the light emitting diode 18.

  When an output is generated from the constant power control signal generation unit 42, outputs from the low current detection unit 47 and the low voltage detection unit 45 are generated from the output switching unit 49 and input to the control circuit 26. In this state, the control circuit 26 monitors the output of each of the low current detection unit 47 and the low voltage detection unit 45. When the comparator 471 of the low current detector 47 matches the output of the current detector 19 and the reference value of the reference signal source 48 (or the comparator 451 of the low voltage detector 45 outputs the reference signal and the output of the voltage detector 20). When the reference value of the source 46 coincides (point E shown in FIG. 4), the control circuit 26 stops the on / off operation of the switching transistor 15 by this detection signal, cancels the constant power control, and turns off the light emitting diode 18.

  Here, Ic4 and Vc2 shown in FIG. 4 are the minimum current and the minimum voltage that guarantee the allowable brightness for the light-emitting diode 18.

  Accordingly, even in this case, if the applied voltage of the light emitting diode 18 may increase due to a load abnormality or the like, the control for the light emitting diode 18 is immediately shifted to the constant power control, so in the first embodiment. The same effect as described can be obtained.

  In addition, this invention is not limited to the said embodiment, In the implementation stage, it can change variously in the range which does not change the summary. For example, in the above-described embodiment, the example of the light emitting diode is described as the semiconductor light emitting element, but the present invention can be applied to the case where another semiconductor light emitting element such as a laser diode is used. In the above-described embodiment, the AC power supply 11 is described. However, the AC power supply 11 may be provided outside the apparatus. Furthermore, in the above-described embodiment, an example of an analog circuit has been described, but a control method using a microcomputer or digital processing can also be adopted.

Furthermore, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and is described in the column of the effect of the invention. If the above effect is obtained, a configuration from which this configuration requirement is deleted can be extracted as an invention.
The invention described in the scope of the claims at the beginning of the present application is added below.
[C1]
A semiconductor light emitting device;
Constant current control signal generating means for generating a constant current control signal based on a current flowing through the semiconductor light emitting element;
Constant voltage control signal generating means for generating a constant voltage control signal based on a voltage applied to the semiconductor light emitting element;
Based on a constant current control signal generated by the constant current control signal generation means, constant current control is performed on the semiconductor light emitting element, and the voltage control signal is generated when a voltage applied to the semiconductor light emitting element reaches a predetermined value. Control means for performing constant voltage control on the semiconductor light emitting element based on a constant voltage control signal generated by the means;
A power supply device comprising:
[C2]
A semiconductor light emitting device;
Constant current control signal generating means for generating a constant current control signal based on a current flowing through the semiconductor light emitting element;
Constant power control signal generating means for generating a constant power control signal based on a current flowing through the semiconductor light emitting element and a voltage applied to the semiconductor light emitting element;
Based on the constant current control signal generated by the constant current control signal generating means, constant current control is performed on the semiconductor light emitting element, and when the voltage applied to the semiconductor light emitting element reaches a predetermined value, the constant power control signal Control means for performing constant power control on the semiconductor light emitting element based on a constant power control signal generated by the generating means;
A power supply device comprising:
[C3]
A lighting fixture comprising: the power supply device according to [C1] or [C2]; and a fixture main body having the power supply device.

The front view which shows the lighting fixture applied to the 1st Embodiment of this invention, a side view, and a cross-sectional view. The figure which shows schematic structure of the power supply device concerning the 1st Embodiment of this invention. The figure which shows the load characteristic of the power supply device concerning 1st Embodiment. The figure which shows schematic structure of the power supply device concerning the 2nd Embodiment of this invention. The figure which shows the load characteristic of the power supply device concerning 2nd Embodiment. The figure which shows the load characteristic of the conventional power supply device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Instrument main body, 1a ... Top plate, 3 ... Power supply unit board | substrate 4 ... Constant current circuit board | substrate, 5 ... LED module 6 ... Light emitting diode, 11 ... AC power supply 100 ... Power supply device, 10 ... DC-DC converter 14 ... Switching transformer, 15 ... Switching transistor 18 ... Light emitting diode, 19 ... Current detector, 20 ... Voltage detector 22 ... Constant current control signal generator, 24 ... Constant voltage control signal generator 26 ... Control circuit, 27, 49 ... Output Switching unit, 29 ... low current detection unit 42 ... constant power control signal generation unit, 45 ... low voltage detection unit 47 ... low current detection unit.

Claims (2)

A semiconductor light emitting device;
Constant current control signal generating means for generating a constant current control signal based on a current flowing through the semiconductor light emitting element;
Constant voltage control signal generating means for generating a constant voltage control signal based on a voltage applied to the semiconductor light emitting element;
Current detection means for detecting whether a current flowing through the semiconductor light emitting element is a minimum current that guarantees an acceptable brightness for the semiconductor light emitting element;
Based on a constant current control signal generated by the constant current control signal generation means, constant current control is performed on the semiconductor light emitting element, and the voltage control signal is generated when a voltage applied to the semiconductor light emitting element reaches a predetermined value. Performing constant voltage control on the semiconductor light emitting element based on a constant voltage control signal generated by the means, and when the current detecting means detects that the current flowing through the semiconductor light emitting element is the minimum current, Control means for canceling constant voltage control and turning off the semiconductor light emitting element;
A power supply device comprising: An illumination fixture comprising: the power supply device according to claim 1; and an appliance main body having the power supply device.

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