JP4529657B2 - Light emitting diode lighting device and lighting fixture - Google Patents

Description

  The present invention relates to a light emitting diode lighting device for lighting a light emitting diode, and a lighting fixture using the same.

  FIG. 7 is a circuit diagram showing a configuration of a light-emitting diode lighting device according to the background art (see, for example, Patent Document 1). A light-emitting diode lighting device 101 shown in FIG. 7 is a so-called DC constant current power supply device that supplies a constant current to the light-emitting diode 115 connected to the terminal block 110, and is connected to a commercial AC power supply AC via the terminal block 102. A diode bridge 103 and a capacitor 104 that smoothes the power supply voltage full-wave rectified by the diode bridge 103 are provided, and a series circuit of a primary winding 106 of the transformer 105 and a transistor 108 is connected in parallel with the capacitor 104. . The voltage across the secondary winding 107 of the transformer 105 is applied across the capacitor 109 via the diode 116 and is smoothed by the capacitor 109 and converted into a DC voltage.

  The light emitting diode 115 may be one in which one or a plurality of light emitting diode elements are connected in series, and the number of light emitting diode elements connected in series is appropriately increased or decreased. Further, the connection point between the capacitor 109 and the diode 116 is connected to one connection terminal 111 in the terminal block 110 to which the light emitting diode 115 is connected, and the other connection terminal 112 is connected to the ground via the resistor 113. Yes. The resistor 113 is a resistor for detecting a current output from the terminal block 110 to the light emitting diode 115, and generates a voltage at the connection terminal 112 that is proportional to the current flowing through the light emitting diode 115.

  The connection terminal 112 is connected to the non-inverting input terminal of the comparator 114, a predetermined reference voltage Vref is applied to the inverting input terminal of the comparator 114, and the output terminal of the comparator 114 is connected to the PWM control unit 117. The PWM control unit performs PWM (Pulse Width Modulation) control by changing the on / off duty of the transistor 108 so that the output signal of the comparator 114 is at a high level, that is, the voltage at the connection terminal 112 is higher than the reference voltage Vref. For example, the output voltage from the terminal block 110 is lowered to reduce the current output from the terminal block 110 to the light emitting diode 115, while the output signal of the comparator 114 is low level, that is, the voltage of the connection terminal 112 is lower than the reference voltage Vref. If so, the output voltage from the terminal block 110 is increased to increase the current output from the terminal block 110 to the light emitting diode 115.

As a result, the light emitting diode lighting device 101 causes a constant current to flow through the light emitting diode 115 connected to the terminal block 110. For example, even if the number of light emitting diodes used as the light emitting diode 115 is increased or decreased. Is made to emit light at a constant brightness (see, for example, Patent Document 1).
JP 2002-244103 A

  By the way, in the light emitting diode lighting device 101 as described above, if the light emitting diode 115 is mistakenly connected to the terminal block 110 in the reverse direction, no current flows between the connection terminals 111 and 112, so that the current also flows through the resistor 113. Does not flow and the voltage drop due to the resistor 113 does not occur. As a result, the voltage of the connection terminal 112 is fixed to the reference voltage Vref or lower. Then, as a result of the output signal from the comparator 114 to the PWM control unit 117 being fixed at a low level, the PWM control unit 117 performs PWM control to increase the current output from the terminal block 110 to the light emitting diode 115, and the connection is made. The output voltage between the terminals 111 and 112 is continuously raised. As a result, the output voltage between the connection terminals 111 and 112 exceeds the reverse withstand voltage of the light emitting diode 115, and the light emitting diode 115 is destroyed.

  The present invention is an invention made in view of such a problem, a light emitting diode lighting device capable of suppressing the destruction of the light emitting diode even when the light emitting diode is erroneously connected in the reverse direction, and It aims at providing the lighting fixture provided with this.

  In order to achieve the above-described object, a light-emitting diode lighting device according to the first means of the present invention includes an external connection portion to which a light-emitting diode element for illumination is connected to the outside, and the light-emitting diode to the external connection portion. A direct-current power supply for supplying a direct-current voltage for causing the device to emit light, a current detection unit for detecting a current level of an output current supplied from the direct-current power supply to the external connection, and the direct-current power supply for the illumination Output a detection voltage having a voltage level less than the reverse withstand voltage of the light emitting diode element, and the output level detected when the current level of the output current detected by the current detection unit exceeds a preset reference level. The output level of the DC voltage by the DC power supply unit is changed so that the current level of the current becomes a constant current level for light emission in the light emitting diode element for illumination. It is characterized by comprising a control unit, a.

  In the above-described light emitting diode lighting device, the current detection unit is connected in series with the light emitting diode element for illumination via the external connection unit, and has a forward voltage smaller than that of the light emitting diode element for illumination. It is characterized by comprising a light emitting diode for current detection and a forward voltage detection unit for detecting a forward voltage in the light emitting diode for current detection as a current level of the output current.

  In the above-described light emitting diode lighting device, the control unit causes the detection voltage to be output in a pulse form from the DC power supply unit, and the current detection unit transmits the light emitting diode for illumination via the external connection unit. A transformer having a primary winding connected in series with the element, and a transformer voltage detector for detecting an output voltage of a secondary winding in the transformer as a current level of the output current are provided.

  Furthermore, the lighting fixture according to the second means of the present invention comprises a light-emitting diode lighting device and a housing that houses the light-emitting diode lighting device, and the light-emitting diode lighting device is the above-described light-emitting diode lighting device. It is characterized by being.

  In the light emitting diode lighting device and the lighting fixture having such a configuration, the control unit outputs a detection voltage having a voltage level less than the reverse withstand voltage of the light emitting diode element for lighting from the DC power supply unit to the external connection unit, The detection unit detects the current level of the output current supplied from the DC power supply unit to the external connection unit. When the current level of the output current detected by the current detection unit exceeds a preset reference level, the current level of the output current is set to a constant current level for light emission in the light emitting diode element for illumination. The output level of the DC voltage from the DC power supply unit is changed by the control unit. Accordingly, when the light emitting diode is mistakenly connected in the reverse direction, the current level of the output current detected by the current detection unit does not exceed a preset reference level. Only the detection voltage having a voltage level less than the reverse withstand voltage is applied, and the destruction of the light emitting diode can be suppressed.

  Embodiments according to the present invention will be described below with reference to the drawings. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted.

(First embodiment)
FIG. 1 is a perspective view showing an example of the appearance of a lighting fixture according to the first embodiment of the present invention. The lighting fixture 1 shown in FIG. 1 has a light emitting diode lighting device 3 housed in a substantially rectangular parallelepiped housing 2, and a light emitting diode series circuit (hereinafter abbreviated as “LED series circuit”) 4 as a light source. A translucent shade member 5 is attached on the housing 2 so as to cover the box.

  FIG. 2 is a circuit diagram showing an example of the configuration of the light-emitting diode lighting device 3 shown in FIG. 2 includes a terminal block 33 having external connection terminals 31 and 32, a diode bridge DB1 in which a series circuit of diodes D1 and D2 and a series circuit of diodes D3 and D4 are connected in parallel, a capacitor C1 and C2, transformer T1, transistor Tr1, diode D5, terminal block 36 which is an example of an external connection unit including external connection terminals 34 and 35, current detection unit 37, resistor R1, comparators CP1 and CP2, and PWM control unit 38 It has.

  A commercial AC power supply AC is connected between the external connection terminals 31 and 32, the external connection terminal 31 is connected to the connection point of the diodes D1 and D2, and the external connection terminal 32 is connected to the connection point of the diodes D3 and D4. Has been. A capacitor C1 is connected between the connection point of the diodes D2 and D4 and the connection point of the diodes D1 and D3. A series circuit of the primary winding N1 of the transformer T1 and the transistor Tr1 is connected in parallel with the capacitor C1. Further, one end of the secondary winding N2 in the transformer T1 and the anode of the diode D5 are connected, and the cathode of the diode D5 is connected to the ground via the capacitor C2 and to the external connection terminal 34. The other end of the next winding N2 is connected to the ground.

  Further, the external connection terminal 35 is connected to the ground via the current detection unit 37 and the resistor R1, and the connection point between the current detection unit 37 and the resistor R1 is connected to the non-inverting input terminal of the comparator CP1, and the current detection unit 37. The signal output terminal is connected to the non-inverting input terminal of the comparator CP2. Preset reference voltages Vref1 and Vref2 are respectively supplied to the inverting input terminals of the comparators CP1 and CP2. Reference voltages Vref1 and Vref2 will be described later.

  Then, the diode bridge DB1, the capacitor C1, the transformer T1, the transistor Tr1, the diode D5, and the capacitor C2 generate a DC voltage at both ends of the capacitor C2 based on the commercial power supply voltage received at the terminal block 33, and the DC voltage is A DC power supply unit 39 is configured to be supplied to the LED series circuit 4 connected to the outside. Further, the output current level supplied from the DC power supply unit 39 to the terminal block 36 is detected by the current detection unit 37 and the resistor R1. The current detection unit 37 detects a detection current for detecting the connection direction of the LED series circuit 4, for example, a detection current of 5 mA, for example, a current transformer, a Hall element sensor, and a resistor (for example, a 10Ω resistor). Constructed using. The resistor R1 is a resistor for detecting a constant current for lighting the LED series circuit 4, for example, a current of 0.5 A, and a resistor of 50 mΩ, for example, is used.

  The output signals of the comparators CP1 and CP2 are both output to the PWM control unit 38, and the control signal output from the PWM control unit 38 is supplied to the base of the transistor Tr1. The PWM control unit 38 performs PWM control by changing the on / off duty of the transistor Tr1 to make the current supplied from the terminal block 36 to the LED series circuit 4 connected to the outside constant. 39 is a circuit unit for controlling the output voltage of 39, and is configured using, for example, an ASIC (Application Specific Integrated Circuit).

  The LED series circuit 4 includes a plurality of light emitting diode elements, for example, two light emitting diode elements 41 and 42 connected in series, and the anode side of the LED series circuit 4 is connected to the external connection terminal 34. The cathode side of the LED series circuit 4 is connected to the external connection terminal 35. Instead of the LED series circuit 4, one light emitting diode element may be used alone, and the LED series circuit 4 may be configured by connecting three or more light emitting diode elements in series.

  Next, the operation of the light-emitting diode lighting device 3 configured as described above will be described. First, the commercial AC voltage supplied from the commercial AC power supply AC to the external connection terminals 31 and 32 is full-wave rectified by the diode bridge DB1, smoothed by the capacitor C1, and in series with the primary winding N1 of the transformer T1 and the transistor Tr1. A DC voltage is applied to the circuit. Next, the PWM control unit 38 performs PWM control so that the DC power supply unit 39 outputs a detection voltage Vd that is less than the reverse withstand voltage (for example, about 4 V) of one light emitting diode element in the LED series circuit 4. As a result, the transistor Tr1 is turned on and off. Then, the pulse voltage generated in the primary winding N1 of the transformer T1 is stepped down by the transformer T1 by turning on and off the transistor Tr1, and the pulse voltage based on the PWM control generated in the secondary winding N2 of the transformer T1 is converted into the diode D5 and the capacitor. The detection voltage Vd, which is smoothed by the smoothing circuit made up of C2 and turned into direct current at both ends of the capacitor C2, is generated.

  Then, the voltage across the capacitor C2, that is, the output voltage of the DC power supply unit 39 is applied to the series circuit of the LED series circuit 4, the current detection unit 37, and the resistor R1 via the terminal block 36. Then, if the LED series circuit 4 is normally connected to the terminal block 36, the detection voltage Vd is applied in the forward direction of the LED series circuit 4, so that the forward current of the LED series circuit 4 is the current detection unit. 37 and resistor R1. Then, the current detection unit 37 detects the forward current of the LED series circuit 4 and outputs a detection voltage corresponding to the detected current level to the comparator CP2.

  Next, the detection voltage output from the current detection unit 37 is compared with the reference voltage Vref2 by the comparator CP2. The reference voltage Vref2 is a voltage of the detection voltage output from the current detection unit 37 corresponding to the reverse current (for example, about 1 to 9 μA) that flows when the detection voltage Vd is applied to the LED series circuit 4 in the reverse direction. The level is set as the lower limit, and is output from the current detection unit 37 corresponding to a current value less than a forward current (for example, 10 to 90 mA) that flows when the detection voltage Vd is applied to the LED series circuit 4 in the forward direction. A predetermined voltage in a range with the upper limit of the voltage level of the detection voltage is set in advance.

  Thereby, when the LED series circuit 4 is normally connected to the terminal block 36, a forward current flows through the LED series circuit 4 in accordance with the detection voltage Vd, so that the detection voltage from the current detection unit 37 is the reference voltage. When the output signal of the comparator CP2 becomes high level exceeding the voltage Vref2, while the LED series circuit 4 is connected to the terminal block 36 in the reverse direction, no forward current flows through the LED series circuit 4, The detection voltage from the detection unit 37 is equal to or lower than the reference voltage Vref2, and the output signal of the comparator CP2 is set to a low level.

  Now, since the LED series circuit 4 is normally connected to the terminal block 36, the output signal of the comparator CP2 is output to the PWM controller 38 at a high level. When the output signal of the comparator CP2 becomes a high level, that is, the current level detected by the current detection unit 37 is reversed when the detection voltage Vd is applied to the LED series circuit 4 in the reverse direction. In order to cause the LED series circuit 4 to emit light with brightness suitable for illumination when the directional current is exceeded, PWM control is performed to change the on / off duty of the transistor Tr1 and increase the output voltage of the DC power supply unit 39.

  Next, the forward current flowing through the LED series circuit 4 and the resistor R1 through the terminal block 36 increases, and the terminal voltage of the resistor R1 increases. As a result, the voltage input to the non-inverting input terminal of the comparator CP1 increases. . Then, the comparator CP1 compares the terminal voltage of the resistor R1 with the reference voltage Vref1. The reference voltage Vref1 is set to a terminal voltage obtained by the resistor R1 corresponding to a constant current value Iop (for example, a current value of about 0.1 A to 1 A) suitable for causing the LED series circuit 4 to emit light as illumination. ing. When the terminal voltage of the resistor R1 exceeds the reference voltage Vref1, the output signal of the comparator CP2 is output to the PWM controller 38 at a high level. Then, the PWM control unit 38 stops the increase in the output voltage from the DC power supply unit 39, and the supply current from the terminal block 36 to the LED series circuit 4 is set to a constant current value Iop.

  Thus, when the LED series circuit 4 is normally connected to the terminal block 36, a constant current value Iop suitable for causing the LED series circuit 4 to emit light as illumination is supplied from the terminal block 36 to the LED series circuit 4. Thus, the LED series circuit 4 can emit light with a constant brightness.

  On the other hand, when the LED series circuit 4 is connected to the terminal block 36 in the reverse direction, no forward current flows through the LED series circuit 4, so that the detection voltage from the current detection unit 37 becomes the reference voltage Vref2 or less and the comparator CP2 Output signal becomes low level. Then, the PWM control unit 38 continues the PWM control for outputting the detection voltage Vd from the DC power supply unit 39, and the detection voltage Vd is applied to the LED series circuit 4 connected to the terminal block 36 in the reverse direction. to continue. In this case, since the detection voltage Vd is set to a voltage that does not satisfy the reverse breakdown voltage of one light emitting diode element in the LED series circuit 4, it is possible to suppress the destruction of the LED series circuit 4 due to overvoltage application. Thereby, even if it is a case where the LED series circuit 4 is connected by the reverse direction accidentally, destruction of a LED series circuit can be suppressed.

  In addition, although the direct-current power supply part 39 showed the example which produces | generates the direct-current voltage which light-emits the LED series circuit 4 based on the commercial alternating-current power supply voltage supplied from the outside, for example, PWM control is performed for the direct-current voltage output from the battery. It may be a DC-DC converter that converts the LED series circuit 4 into a direct current voltage for emitting light in accordance with a control signal from the unit 38.

  In addition, the DC power supply unit 39 has a configuration of an insulated flyback power supply, but may be of any other configuration as long as the output voltage can be controlled to output a constant current.

(Second Embodiment)
Next, a light-emitting diode lighting device according to a second embodiment of the present invention will be described. FIG. 3 is a circuit diagram showing an example of the configuration of the light-emitting diode lighting device 3a according to the second embodiment of the present invention. The light emitting diode lighting device 3a shown in FIG. 3 is different from the light emitting diode lighting device 3 shown in FIG. 2 in the following points. That is, the light-emitting diode lighting device 3 a shown in FIG. 3 includes a light-emitting diode D 6 for current detection instead of the current detection unit 37. The light emitting diode D6 is a light emitting diode for display, and a diode having a forward voltage Vf smaller than that of the light emitting diode elements 41 and 42 is used. For example, when a current having a current value Iop is passed, the forward voltage Vf of the light emitting diode elements 41 and 42 for illumination is about 3.5V to 4.5V, whereas the forward voltage Vf as the light emitting diode D6. Is about 1.5V to 2.5V.

  The anode of the light emitting diode D6 is connected to the external connection terminal 35, and the cathode is connected to the resistor R1. The anode of the light emitting diode D6 is connected to the non-inverting input terminal of the differential amplifier AMP1 via the resistor R2, and the cathode of the light emitting diode D6 is connected to the inverting input terminal of the differential amplifier AMP1 via the resistor R3. By connecting the output terminal and the inverting input terminal of the dynamic amplifier AMP1 by the resistor R4, a current detection signal indicating the current level of the output current supplied from the DC power supply unit 39 to the terminal block 36 is transmitted in the order of the light emitting diode D6. A differential amplifier circuit 51, which is an example of a forward voltage detector generated by amplifying the directional voltage Vf, is configured. The output terminal of the differential amplifier AMP1 is connected to the non-inverting input terminal of the comparator CP2.

  Since the other configuration is the same as that of the light-emitting diode lighting device 3 shown in FIG. 2, the description thereof is omitted, and the operation of the light-emitting diode lighting device 3a shown in FIG. 3 will be described below. First, in the same manner as the light emitting diode lighting device 3 shown in FIG. 2, the detection voltage Vd is output from the DC power supply unit 39 according to the control signal from the PWM control unit 38, and the LED series circuit 4, the light emitting diode D6, And applied to the series circuit of the resistor R1. In this case, if the LED series circuit 4 is normally connected to the terminal block 36, the detection voltage Vd is applied in the forward direction of the LED series circuit 4, so that the forward current of the LED series circuit 4 becomes a light emitting diode. D6 and the resistor R1 flow.

  Then, the light emitting diode D6 emits light, and the forward voltage Vf of the light emitting diode D6 is amplified by the differential amplifier circuit 51 to exceed the reference voltage Vref2, and the output signal of the comparator CP2 is output to the PWM control unit 38 at a high level. Hereinafter, similarly to the light emitting diode lighting device 3 shown in FIG. 2, the output voltage of the DC power supply unit 39 is increased by the PWM control unit 38, and the supply current from the terminal block 36 to the LED series circuit 4 is constant suitable for illumination. Current value Iop.

  In this case, since the forward voltage Vf of the light emitting diode D6 is smaller than that of the light emitting diode elements 41 and 42, the power loss due to the light emitting diode D6 can be reduced as compared with the case where the same light emitting diode as the light emitting diode elements 41 and 42 is used. it can.

  Thus, when the LED series circuit 4 is normally connected to the terminal block 36, a constant current value Iop suitable for causing the LED series circuit 4 to emit light as illumination is supplied from the terminal block 36 to the LED series circuit 4. In addition, the LED series circuit 4 can emit light with a constant brightness, and the light emitting diode D6 emits light. Therefore, the user visually checks the light emitting state of the light emitting diode D6, so that the LED series circuit 4 is normally connected to the terminal. It can be confirmed that it is connected to the stand 36. Further, since the light emitting diode D6 is turned off even when the LED series circuit 4 is broken, the user checks the light emitting state of the light emitting diode D6 to confirm whether the LED series circuit 4 is broken or not. Can do.

  FIG. 4 is an explanatory diagram showing an example of an application using the light-emitting diode lighting device 3a. The light emitting diode lighting device 3a in FIG. 4 omits the portions other than the terminal block 36, the light emitting diode D6, and the resistor R1. In FIG. 4, the external connection terminal 34 is connected to the anode of the LED series circuit 4 via the switch SW <b> 1 operated by the user and the wiring 43, and the cathode of the LED series circuit 4 is connected to the external connection terminal via the wiring 44. 35.

  In this case, the switch SW1 is turned on even when the LED series circuit 4 is installed at a position away from the light emitting diode lighting device 3a and the light emitting state of the LED series circuit 4 cannot be confirmed from the position of the light emitting diode lighting device 3a. When a forward current flows through the LED series circuit 4, the light emitting diode D6 is turned on. When the switch SW1 is turned off or the LED series circuit 4 is broken, the light emitting diode D6 is turned off. , It is possible to easily confirm the light emission state of the LED series circuit 4 and the presence or absence of a disconnection failure.

  On the other hand, when the LED series circuit 4 is connected to the terminal block 36 in the reverse direction, no forward current flows through the LED series circuit 4, so the light emitting diode D6 is turned off and the forward voltage Vf of the light emitting diode D6 is reduced. Even when amplified by the differential amplifier circuit 51, the voltage drops below the reference voltage Vref2, and the output signal of the comparator CP2 is output to the PWM controller 38 at a low level. Then, similarly to the light-emitting diode lighting device 3 shown in FIG. 2, the detection voltage Vd is continuously applied to the LED series circuit 4 connected to the terminal block 36 in the reverse direction. In this case, since the detection voltage Vd is set to a voltage that does not satisfy the reverse breakdown voltage of one light emitting diode element in the LED series circuit 4, it is possible to suppress the destruction of the LED series circuit 4 due to overvoltage application. Thereby, even if it is a case where the LED series circuit 4 is connected to the reverse direction accidentally, destruction of the LED series circuit 4 can be suppressed.

  Instead of the light emitting diode D6, a diode having a forward voltage Vf smaller than that of the light emitting diode elements 41 and 42 may be used. In this case, for example, compared to the case where the current is detected using a resistor instead of the light emitting diode D6, the diode reduces the increase in the forward voltage Vf when the forward current increases. When light is emitted at a constant current value Iop, power loss in the diode can be reduced.

(Third embodiment)
Next, a light-emitting diode lighting device according to a third embodiment of the present invention will be described. FIG. 5 is a circuit diagram showing an example of the configuration of a light-emitting diode lighting device 3b according to the third embodiment of the present invention. The light emitting diode lighting device 3b shown in FIG. 5 is different from the light emitting diode lighting device 3 shown in FIG. 2 in the following points. That is, in the light emitting diode lighting device 3b shown in FIG. 5, the primary winding N3 of the pulse transformer T2 (transformer) is interposed between the external connection terminal 35 and the resistor R1 instead of the current detection unit 37. An example of a transformer voltage detector that outputs a detection voltage representing a current level supplied from the terminal block 36 to the outside to the comparator CP2 by smoothing the pulse signal output from the secondary winding N4 of the pulse transformer T2. A certain current detection unit 37a is provided.

  The current detection unit 37a includes, for example, a pulse transformer T2, a resistor R2 connected in parallel to the secondary winding N4 of the pulse transformer T2, a series circuit of diodes D7 and D8, and a series circuit of diodes D9 and D10. A diode bridge DB2 in which a connection point between the diodes D7 and D8 and a connection point between the diodes D9 and D10 are connected to both ends of the resistor R2, and a connection point between the connection point between the diodes D8 and D10 and the ground. And a smoothing capacitor C3.

  In the DC power supply unit 39a, a transistor Tr2 is connected in series with the capacitor C2, and a series circuit of the transistor Tr2 and the capacitor C2 is connected between the diode D5 and the ground. Further, a series circuit of a resistor R5 and a resistor R6 is connected in parallel with the series circuit of the transistor Tr2 and the capacitor C2. The DC power supply unit 39a includes a changeover switch SW2 that connects the pole 21 to one of the contacts 22 and 23 according to the output signal of the comparator CP2, and the pole 21 of the changeover switch SW2 is connected to the external connection terminal 34. The contact 22 is connected to a connection point between the resistor R5 and the transistor Tr2, and the contact 23 is connected to a connection point between the resistor R5 and the resistor R6. That is, the pole 21 of the changeover switch SW2 serves as the output unit of the DC power supply unit 39a.

  The resistors R5 and R6 divide the rectangular wave voltage applied to the series circuit of the resistor R5 and the resistor R6 by PWM control, and the peak voltage is equal to or less than the reverse breakdown voltage of one light emitting diode element in the LED series circuit 4. The resistance value is set to generate a rectangular wave voltage Vp which is an example of the detection voltage.

  Further, a latch circuit 52 that controls on / off of the transistor Tr2 and switching of the changeover switch SW2 based on output signals of the comparators CP1 and CP2 is further provided. The latch circuit 52 outputs, for example, a signal obtained by ORing the output signal of the comparator CP1 and the output signal of the comparator CP2 to the base of the transistor Tr2 and the changeover switch SW2.

  The changeover switch SW2 is switched to the contact 23 side when the output signal of the latch circuit 52 is low level, and is switched to the contact 22 side when the output signal of the latch circuit 52 is high level. That is, when the output signal of the latch circuit 52 is low level, the rectangular wave voltage Vp divided by the resistors R5 and R6 is output to the external connection terminal 34, and the output signal of the latch circuit 52 is high level. The LED series circuit 4 light emission voltage applied to the series circuit of the resistors R5 and R6 is output to the external connection terminal 34.

  Since the other configuration is the same as that of the light-emitting diode lighting device 3 shown in FIG. 2, the description thereof will be omitted, and the operation of the present embodiment will be described below. First, similarly to the light emitting diode lighting device 3 shown in FIG. 2, the commercial AC voltage supplied from the commercial AC power supply AC to the external connection terminals 31 and 32 is full-wave rectified by the diode bridge DB1 and smoothed by the capacitor C1. Thus, a DC voltage is applied to the series circuit of the primary winding N1 of the transformer T1 and the transistor Tr1.

  Next, when the transistor Tr1 is turned on and off by the PWM control unit 38, the rectangular wave voltage generated in the primary winding N1 of the transformer T1 is stepped down by the transformer T1, and the voltage generated in the secondary winding N2 of the transformer T1. Is applied to the series circuit of the transistor Tr2 and the capacitor C2 via the diode D5.

  Then, in the initial state, since the output signals of the comparators CP1 and CP2 are both low level, the output signal supplied from the latch circuit 52 to the base of the transistor Tr2 and the changeover switch SW2 is also low level, and the transistor Tr2 is turned off. Therefore, the rectangular wave voltage generated in the secondary winding N2 is applied to the resistors R5 and R6 without being smoothed by the capacitor C2, and is divided by the resistors R5 and R6. Here, since the output signal of the latch circuit 52 is at the low level, the changeover switch SW2 is connected to the contact 23 side, and the rectangular wave voltage generated in the secondary winding N2 is divided by the resistors R5 and R6, A voltage across the resistor R 6, that is, a pulsed rectangular wave voltage Vp is output to the external connection terminal 34.

  FIG. 6 is a waveform diagram showing an example of a signal waveform of the rectangular wave voltage Vp. As shown in FIG. 6, the peak voltage of the rectangular wave voltage Vp is set to be equal to or lower than the reverse withstand voltage Vlim of the light emitting diode elements 41 and 42.

  Then, the rectangular wave voltage Vp is applied to the series circuit of the LED series circuit 4, the primary winding N3 of the pulse transformer T2, and the resistor R1. In this case, if the LED series circuit 4 is normally connected to the terminal block 36, the rectangular wave voltage Vp is applied in the forward direction of the LED series circuit 4, so that the pulse-like order corresponding to the rectangular wave voltage Vp is applied. Directional current flows through primary winding N3 and resistor R1. Next, a pulse voltage is generated in the secondary winding N4 of the pulse transformer T2, and the pulse voltage is rectified by the diode bridge DB2, and the voltage smoothed by the capacitor C3 is supplied to the outside from the terminal block 36. Is output from the current detector 37a to the comparator CP2.

  Then, the detection voltage output from the current detection unit 37a exceeds the reference voltage Vref2, and the output signal of the comparator CP2 is output to the latch circuit 52 and the PWM control unit 38 at a high level, and the base voltage of the transistor Tr2 is output by the latch circuit 52. The transistor Tr2 is turned on and the changeover switch SW2 is switched to the contact 22 side, and the output voltage of the DC power supply unit 39 is reduced by the PWM control unit 38 as in the light emitting diode lighting device 3 shown in FIG. Be raised. In this case, since the transistor Tr2 is on, the output voltage of the DC power supply unit 39 is smoothed by the capacitor C2 to become a DC voltage, which is applied to the series circuit of the resistors R5 and R6.

  Since the output signal of the latch circuit 52 is at the high level, the changeover switch SW2 is switched to the contact 22 side, and the DC voltage smoothed by the capacitor C2 is divided by the series circuit of the resistors R5 and R6. Without being supplied to the external connection terminal 34 via the changeover switch SW2, the supply current from the terminal block 36 to the LED series circuit 4 is set to a constant current value Iop.

  Next, when the LED series circuit 4 is turned on and the supply current from the terminal block 36 to the LED series circuit 4 becomes a constant DC current value Iop, no voltage is generated in the secondary winding N4 of the pulse transformer T2. The output signal of the comparator CP2 becomes a low level, but when the LED series circuit 4 is lit, the output signal of the comparator CP1 becomes a high level as in the light emitting diode lighting device 3 shown in FIG. The base voltage of the transistor Tr2 is maintained at a high level, the transistor Tr2 is kept on, and the changeover switch SW2 is maintained on the contact 22 side.

  On the other hand, when the LED series circuit 4 is connected to the terminal block 36 in the reverse direction, no forward current flows through the LED series circuit 4, so that a pulsed current corresponding to the rectangular wave voltage Vp is generated in the primary winding N3. Therefore, the detection voltage output from the current detection unit 37a is equal to or lower than the reference voltage Vref2, and the output signal of the comparator CP2 is output to the latch circuit 52 and the PWM control unit 38 at a low level, which is shown in FIG. Similarly to the light emitting diode lighting device 3, the rectangular wave voltage Vp is continuously applied to the LED series circuit 4 connected to the terminal block 36 in the reverse direction.

  In this case, since the peak voltage of the rectangular wave voltage Vp is set to a voltage equal to or lower than the reverse breakdown voltage of one light emitting diode element in the LED series circuit 4, the LED series circuit 4 may be destroyed by application of an overvoltage. It is suppressed. Thereby, even if it is a case where the LED series circuit 4 is connected to the reverse direction accidentally, destruction of the LED series circuit 4 can be suppressed.

  When the light emitting diode lighting device 3b is used in a no-load state, for example, as shown in FIG. 4, when the LED series circuit 4 is connected to the outside of the terminal block 36 via the switch SW1, the switch SW1 is turned off. In this state, since the transistor Tr2 is turned off, no current flows through the capacitor C2, so that the life of the capacitor C2 can be extended, and as a result, the life of the light emitting diode lighting device 3b can be extended.

  Further, when the current of the current value Iop is supplied in the lighting state of the LED series circuit 4, for example, the current that flows is compared with the case where the current is detected by the voltage drop of the resistance using a resistor instead of the pulse transformer T2. Since the loss of the pulse transformer T2 is small when the current increases, the power loss in the current detection unit 37a with respect to the lighting current of the LED series circuit 4 can be reduced.

It is a perspective view which shows an example of the external appearance of the lighting fixture which concerns on the 1st Embodiment of this invention. It is a circuit diagram which shows an example of a structure of the light emitting diode lighting device shown in FIG. It is a circuit diagram which shows an example of a structure of the light emitting diode lighting device which concerns on the 2nd Embodiment of this invention. It is explanatory drawing which shows an example of the application using the light emitting diode lighting device shown in FIG. It is a circuit diagram which shows an example of a structure of the light emitting diode lighting device which concerns on the 3rd Embodiment of this invention. It is a wave form diagram which shows an example of the signal waveform of the rectangular wave voltage Vp. It is a circuit diagram which shows the structure of the light emitting diode lighting device which concerns on background art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lighting fixture 2 Case 3, 3a, 3b Light emitting diode lighting device 4 LED series circuit 5 Seed member 31, 32 External connection terminal 33, 36 Terminal block 34, 35 External connection terminal 37, 37a Current detection part 38 PWM control part 39 , 39a DC power supply units 41, 42 Light emitting diode elements 43, 44 Wiring 51 Differential amplifier circuit 52 Latch circuit AMP1 Differential amplifier C1, C2, C3 Capacitor CP1, CP2 Comparators D1, D2, D3, D4, D5, D7, D8 , D9, D10 Diode D6 Light emitting diode DB1, DB2 Diode bridge R1, R2, R3, R4 Resistor T1 Transformer T2 Pulse transformer Tr1, Tr2 Transistor

Claims (4)

An external connection part to which a light emitting diode element for illumination is connected to the outside;
A DC power supply for supplying a DC voltage for causing the light emitting diode element to emit light to the external connection;
A current detection unit for detecting a current level of an output current supplied from the DC power supply unit to the external connection unit;
A detection voltage that is a voltage level that does not satisfy the reverse withstand voltage of the illumination light emitting diode element is output from the DC power supply unit, and a current level of the output current detected by the current detection unit is set in advance as a reference level A control unit that changes the output level of the DC voltage by the DC power supply unit in order to make the current level of the output current to be a constant current level for light emission in the light emitting diode element for illumination,
A light-emitting diode lighting device comprising: The current detection unit is connected in series with the light emitting diode element for illumination through the external connection unit, a light emitting diode for current detection having a forward voltage smaller than that of the light emitting diode element for illumination,
The light emitting diode lighting device according to claim 1, further comprising a forward voltage detecting unit that detects a forward voltage in the current detecting light emitting diode as a current level of the output current. The control unit outputs the detection voltage in a pulse form from the DC power supply unit,
The current detection unit includes a transformer in which a primary winding is connected in series with the light emitting diode element for illumination via the external connection unit, and an output voltage of a secondary winding in the transformer is a current level of the output current. The light emitting diode lighting device according to claim 1, further comprising: a transformer voltage detection unit that detects A light emitting diode lighting device;
A housing for housing the light emitting diode lighting device;
With
The said light emitting diode lighting device is the light emitting diode lighting device in any one of Claims 1-3, The lighting fixture characterized by the above-mentioned.

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