JP5495009B2 - Lighting device - Google Patents

Description

  The present invention relates to an illumination device capable of dimming an illumination light source, and more particularly, to an illumination device capable of dimming an illumination light source such as a fluorescent lamp or an LED using a phase control type dimming circuit.

  2. Description of the Related Art Conventionally, a phase control type dimming circuit that performs dimming of an illumination light source using a bidirectional three-terminal thyristor (hereinafter simply referred to as a thyristor) is known. This dimmer circuit is typically supplied to the illumination light source by changing the duty ratio of the commercial AC power supply voltage supplied to the dimmer circuit by controlling the conduction angle of the thyristor by its control unit. The amount of electric power to be changed is changed to perform dimming.

  Such a phase control type dimmer circuit has been widely used as a dimmer for an incandescent lamp. However, when applied to an illumination light source having a small load current such as a fluorescent lamp or an LED, It is known that the following problems occur. That is, in the thyristor, after a trigger is input and turned on, a current exceeding a predetermined minimum holding current needs to flow between main terminals in order to maintain the on state. Therefore, when this dimming circuit is applied to an illumination device for an illumination light source such as a fluorescent lamp or an LED having a small load current, it becomes difficult to stably maintain the thyristor on-state by the load current of the light source. Will cause problems such as flickering of lighting.

  In order to cope with such a problem, conventionally, a lighting device (for example, refer to Patent Document 1) which maintains a minimum holding current of a thyristor using a constant current circuit, or a converter circuit for lighting an LED. An illuminating device having a dummy load that is driven by a control signal is proposed (for example, see Patent Document 2).

However, in the configuration using the constant current circuit as described in Patent Document 1, even when the minimum holding current of the thyristor is maintained by the load current, the current always flows through the constant current circuit. There is a problem that power consumption increases.
Moreover, in the illuminating device using the dummy load as described in Patent Document 2, since the dummy load is driven by the control signal from the converter circuit for turning on the LED, it is difficult to generate an optimal control signal. In addition, there is a problem that the circuit scale increases.

  Therefore, in view of these problems, the present inventor has a dimming circuit that controls the phase of the current supplied to the illumination light source by controlling the conduction angle of the AC supplied from the commercial AC power supply, and the dimming A rectifier circuit that rectifies an AC voltage output from the circuit; a smoothing circuit that smoothes a DC voltage output from the rectifier circuit; and a lighting circuit that emits an illumination light source in accordance with the voltage smoothed by the smoothing circuit; In the illuminating device having the above, an illuminating device including a load circuit that maintains a minimum holding current at which the dimming circuit operates normally between the rectifier circuit and the smoothing circuit has been proposed (Japanese Patent Application No. 2009-146879).

JP 2007-227155 A Special table 2007-538378 gazette

  However, in the technique previously proposed by the present inventor, when a plurality of illumination light sources are lit by an illumination device having one dimming circuit, an illumination drive including a rectifier circuit, a load circuit, a smoothing circuit, and a lighting circuit A circuit is required for each light source, and since there are a plurality of load circuits corresponding to a plurality of light sources, a current exceeding the minimum holding current required for the dimming circuit flows, which may reduce the efficiency of the entire lighting device There is room for improvement.

  The present invention has been made in view of the above problems, and it is possible to prevent malfunctions resulting from the shortage of the minimum holding current of the phase control type dimming circuit while having a simple and inexpensive circuit configuration, And it aims at providing the illuminating device which can light the 1 or more light source for illumination efficiently with one light control circuit.

  The following aspects of the present invention exemplify the configuration of the present invention, and will be described separately for easy understanding of various configurations of the present invention. Each section does not limit the technical scope of the present invention, and some of the components of each section are replaced, deleted, or further, while referring to the best mode for carrying out the invention. Those to which the above components are added can also be included in the technical scope of the present invention.

(1) One dimming circuit that controls the phase of current supplied to one or more illumination light sources by controlling the conduction angle of alternating current supplied from a commercial AC power supply, and the one or more illuminations In the lighting device including one or more drive circuits that respectively drive the light sources, each of the drive circuits outputs a rectifier circuit that rectifies an AC voltage output from the dimming circuit, and the rectifier circuit outputs the rectifier circuit. A smoothing circuit that smoothes a DC voltage; and a lighting circuit that emits light from the illumination light source in accordance with the voltage smoothed by the smoothing circuit, the dimming circuit and the one or more drive circuits; A load circuit that maintains a minimum holding current at which the dimming circuit operates normally , and the load circuit detects a current flowing through the dimming circuit and lacks the minimum holding current of the dimming circuit Control signal to induce minutes Two sets of circuit blocks each including a constant current control circuit that outputs and a variable current circuit that inputs a control signal from the constant current control circuit and flows an insufficient amount of the minimum holding current of the dimming circuit, Each of the blocks maintains a minimum holding current at which the dimming circuit operates normally with respect to currents in different directions among the bidirectional currents whose phases are controlled by the dimming circuit. (Claim 1).

( 2 ) In the illumination device according to item ( 1 ), the constant current control circuit includes a detection resistor that detects a current flowing through the dimming circuit and a semiconductor element that transmits the control signal. Apparatus (claim 2 ).

( 3 ) In the illumination device according to item ( 2 ), the detection resistor is common to the two sets of circuit blocks (claim 3 ).

( 4 ) In the lighting device according to ( 2 ) or ( 3 ), the detection resistor is a variable resistor whose resistance value can be switched in accordance with a minimum holding current at which the dimming circuit operates normally. An illuminating device characterized in that (Claim 4 ).

  The present invention is configured as described above, so that it is possible to prevent malfunctions resulting from the shortage of the minimum holding current of the phase control type dimming circuit while being a simple and inexpensive circuit configuration, and It is possible to provide an illumination device capable of efficiently lighting a plurality of illumination light sources with a single dimming circuit.

It is a circuit block diagram of the illuminating device in 1st Embodiment of this invention. It is a circuit diagram which shows the load circuit of the illuminating device shown in FIG. In the illuminating device in 1st Embodiment of this invention, it is a current waveform diagram which shows the electric current of each point. It is a circuit diagram which shows the load circuit of the illuminating device in 2nd Embodiment of this invention. It is a circuit diagram which shows the load circuit of the illuminating device in 3rd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
(First embodiment)
The illuminating device 1 shown in FIG. 1 controls one phase of current supplied to a plurality of illumination light sources (loads) 61 to 6n by controlling an AC conduction angle supplied from a commercial AC power supply Vac. The optical circuit 2 and a plurality of drive circuits 71 to 7n that respectively drive the plurality of illumination light sources 61 to 6n are provided, and each of the drive circuits 71 to 7n receives an AC voltage output from the dimming circuit 2. Rectifying circuits 31 to 3n for rectifying, smoothing circuits 41 to 4n for smoothing a DC voltage output from the rectifying circuits 31 to 3n, and illumination light sources 61 to 61 according to voltages smoothed by the smoothing circuits 41 to 4n. Lighting circuits 51 to 5n that emit light of 6n are provided.

  Here, the dimming circuit 2 includes a thyristor Q0, and typically supplies a trigger to the thyristor Q0 at a predetermined conduction angle of the commercial AC power supply Vac to turn on the thyristor Q0. A control unit (not shown) and a variable resistor for changing the degree of dimming of the illumination light sources 61 to 6n by setting the predetermined conduction angle in various ways are included.

  The rectifier circuits 31 to 3n are full-wave rectifier circuits each configured as a well-known diode bridge including four diodes D1 to D4. The smoothing circuits 41 to 4n are respectively composed of a diode D5 and a capacitor C1. It is configured. The lighting circuits 51 to 5n are power conversion circuits that supply power corresponding to the illumination light sources 61 to 6n, respectively. For example, when the illumination light sources 61 to 6n are LEDs, the lighting circuits 51 to 5n are configured from DC-DC converter circuits. Thus, a direct current is output to the illumination light sources 61 to 6n.

  The lighting device 1 in the present embodiment further includes a load circuit 8 that maintains a minimum holding current at which the dimming circuit 2 operates normally between the dimming circuit 2 and the plurality of drive circuits 71 to 7n. The plurality of drive circuits 71 to 7 n are connected in parallel to the load circuit 8.

  The configuration and operation of the load circuit 8 in the present embodiment will be specifically described with reference to FIGS. 2 and 3 as follows. As shown in FIG. 2, the load circuit 8 includes a first circuit block 11 having a constant current control circuit 9 and a variable current circuit 10, and a second circuit block 11a having a constant current control circuit 9a and a variable current circuit 10a. 2 sets of circuit blocks 11 and 11a are provided.

  In the first circuit block 11, the constant current control circuit 9 is constituted by a first detection resistor R1 and a first transistor (NPN transistor) Q1, and the variable current circuit 10 is constituted by a second transistor (NPN transistor) Q2. And the first resistance element R2. In the constant current control circuit 9, one end of the first detection resistor R1 is connected to one end of the output of the dimming circuit 2 (hereinafter, for convenience of explanation, hereinafter referred to as a positive terminal (+)), and the other end is a plurality of rectifiers. It is connected to a connection point between one ends of the circuits 31 to 3n on the input side.

  The base terminal of the first transistor Q1 is connected to the emitter of the second transistor Q2 of the variable current circuit 10 together with the other end of the first detection resistor R1, and the collector terminal of the first transistor Q1 is connected to the second terminal. Connected to the base of the transistor Q2. In the variable current circuit 10, one end of the first resistance element R 2 is connected to the other end of the output of the dimming circuit 2 through the diode D 12 together with the collector terminal of the second transistor Q 2 (for convenience of explanation, hereinafter, the negative electrode The other end is connected to the base terminal of the second transistor Q2 together with the collector terminal of the first transistor Q1.

  In the second circuit block 11a, the constant current control circuit 9a includes a second detection resistor R3 and a third transistor (NPN transistor) Q3, and the variable current circuit 10a includes a fourth transistor (NPN transistor). ) It is constituted by Q4 and the second resistance element R4. In the constant current control circuit 9a, one end of the second detection resistor R3 is connected to the negative terminal (−) of the output of the dimmer circuit 2, and the other end is the other end on the input side of the plurality of rectifier circuits 31 to 3n. It is connected to the connection point between each other.

  The base terminal of the third transistor Q3 is connected to the emitter of the fourth transistor Q4 of the variable current circuit 10a together with the other end of the second detection resistor R3, and the collector terminal of the third transistor Q3 is the fourth terminal. Connected to the base of the transistor Q4. In the variable current circuit 10a, one end of the second resistance element R4 is connected to the positive terminal (+) of the output of the dimming circuit 2 through the diode D13 together with the collector terminal of the fourth transistor Q4. The end is connected to the base terminal of the fourth transistor Q4 together with the collector terminal of the third transistor Q3.

  Further, in the first circuit block 11, a series circuit composed of diodes D6 and D7 and a diode D8 are connected in parallel to the first detection resistor R1, and in the second circuit block 11a, the second detection resistor R1 is connected. A series circuit composed of diodes D9 and D10 and a diode D11 are connected to R3 in parallel.

  In the load circuit 8 configured as described above, the first circuit block 11 and the second circuit block 11a have equivalent functions. As described in detail below, each constant current control circuit 9, 9a detects the current flowing through the dimming circuit 2 by the first and second detection resistors R1 and R3, respectively, and generates a control signal for inducing the shortage of the minimum holding current of the dimming circuit 2 respectively. Are output to the corresponding variable current circuits 10 and 10a by the third transistors Q1 and Q3. The variable current circuits 10 and 10a receive the control signals from the constant current control circuits 9 and 9a, respectively. 2. A shortage of the minimum holding current of the dimming circuit 2 is caused to flow by the fourth transistors Q2 and Q4.

  The load circuit 8 includes two sets of circuit blocks 11 and 11a having such an equivalent function, and the circuit blocks 11 and 11a are connected so as to have opposite polarities with respect to the output from the dimming circuit 2. As a result, each circuit block 11, 11 a maintains a minimum holding current at which the dimming circuit 2 operates normally with respect to currents in different directions among the bidirectional currents whose phases are controlled by the dimming circuit 2. To do.

Next, the operation of the load circuit 8 in this embodiment will be described in detail with reference to FIG. 3 together with FIG. Here, in the current waveform diagram of FIG. 3, the waveforms indicated by A and B are waveforms at A (input of the commercial AC power supply Vac) and B (output of the dimming circuit 2) shown in FIG. , Ic ′, Iv, Iv ′, Io, Io ′ respectively correspond to Ic, Ic ′, Iv, Iv ′, Io, Io ′ shown in FIG. In FIG. 3, the waveforms A and B indicate the half cycle in which the output current of the dimming circuit 2 flows from the positive terminal (+) side to the negative terminal (−) side, the positive half cycle, and the negative terminal (−) side. A half cycle flowing from the positive terminal to the positive terminal (+) side is shown as a negative half cycle, and the waveforms of Ic, Ic ′, Iv, Iv ′, Io, and Io ′ are respectively positive in the directions of the corresponding arrows in FIG. It is shown.
In the example shown in FIG. 3, the dimming circuit 2 has its thyristor Q0 turned on during a conduction angle of 90 ° to 180 ° in the positive half cycle and between a conduction angle of 270 ° to 360 ° in the negative half cycle. (See B in FIG. 3).

  In the load circuit 8, during the conduction angle of 90 ° to 180 °, the diode D13 of the second circuit block 11a conducts, and the load current Iv that is the collector current of the fourth transistor Q4 flows. A total current (hereinafter referred to as drive current) Ic flowing through the drive circuits 71 to 7n flows along with the load current Iv to the second detection resistor R3 of the constant current control circuit 9a. Almost equivalent to the flowing current Io.

  Here, when the drive current Ic decreases, the base-emitter voltage of the third transistor Q3, which is the voltage across the second detection resistor R3, decreases, thereby increasing the base current of the fourth transistor Q4. The collector current Iv also increases. Conversely, when the drive current Ic increases, the base-emitter voltage of the third transistor Q3, which is the voltage across the second detection resistor R3, increases, thereby decreasing the base current of the fourth transistor Q4. The collector current Iv also decreases.

  As shown in FIG. 3, in the positive half cycle, the drive current Ic gradually decreases according to the output waveform B of the dimming circuit 2, but as described above, the fourth transistor Q4 in the variable current circuit 10a. Therefore, the current Io flowing through the dimming circuit 2 is maintained at a value equal to or higher than the minimum holding current of the thyristor Q0 during the conduction angle of 90 ° to 180 °. The

  Further, between the conduction angles of 270 ° to 360 °, the diode D12 of the first circuit block 11 is conducted, and the load current Iv ′ that is the collector current of the second transistor Q2 flows through the load circuit 8. The drive current Ic ′ flows along with the load current Iv ′ through the first detection resistor R1 of the constant current control circuit 9, and the sum of these flows is almost equal to the current Io ′ flowing through the dimming circuit 2.

  Here, when the drive current Ic ′ decreases, the base-emitter voltage of the first transistor Q1, which is the voltage across the first detection resistor R1, decreases, thereby increasing the base current of the second transistor Q2. Therefore, the collector current Iv ′ also increases. Conversely, when the drive current Ic ′ increases, the base-emitter voltage of the first transistor Q1, which is the voltage across the first detection resistor R1, increases, thereby decreasing the base current of the second transistor Q2. Therefore, the collector current Iv ′ is also reduced.

  As shown in FIG. 3, in the negative half cycle, the drive current Ic ′ gradually decreases according to the output waveform B of the dimming circuit 2, but as described above, the second transistor in the variable current circuit 10 Since the collector current Iv ′ of Q2 increases so as to compensate for the decrease, the current Io ′ flowing through the dimming circuit 2 has a value equal to or greater than the minimum holding current of the thyristor Q0 during the conduction angle period of 270 ° to 360 °. Maintained.

  Thus, in the illuminating device 1 according to this embodiment, the drive currents Ic and Ic ′ are reduced by providing the single load circuit 8 between the dimming circuit 2 and the plurality of drive circuits 71 to 7n. However, in each of the negative and positive half cycles, the collector currents Iv and Iv ′ of the second and fourth transistors Q2 and Q4 in the variable current circuits 9 and 9a are increased automatically to compensate for the decrease. Therefore, Io and Io ′ flowing through the dimming circuit 2 are maintained almost constant. Then, by selecting each circuit element of the load circuit 8 so that the currents Io and Io ′ are equal to or larger than the minimum holding current of the thyristor Q0 constituting the dimming circuit 2, malfunction of the dimming circuit 2 can be prevented. it can.

  Therefore, the lighting device 1 according to the present embodiment stably illuminates without causing flickering or the like even when lighting the light sources 61 to 6n having low power consumption (that is, having a small load current) such as fluorescent lamps or LEDs. And can be dimmed. At that time, when the drive currents Ic and Ic ′ increase, the load circuit 8 in the present embodiment automatically increases so that the collector currents Iv and Iv ′ of the second and fourth transistors Q2 and Q4 decrease. In addition to being adjusted, only the current necessary for maintaining the minimum holding current of the thyristor Q0 of the dimming circuit 2 flows, which is advantageous for reducing the power consumption of the lighting device. In particular, the lighting device 1 has only one load circuit 8 for one dimming circuit 2, and the load current of the load circuit 8 is adjusted according to the increase or decrease of the sum of the currents flowing through the drive circuits 71 to 7n. Therefore, even if the plurality of illumination light sources 61 to 6n and the drive circuits 71 to 7n are included, the current more than the current necessary for maintaining the minimum holding current of the dimming circuit 2 in the load circuit 8 thereby. Does not flow, and the efficiency of the lighting device 1 does not decrease.

  Moreover, in the illuminating device 1 in this embodiment, when each drive circuit 71-7n is directly connected to commercial AC power supply Vac without going through the light control circuit 2, it does not produce the additional load current by the load circuit 8. The lighting operation of the illumination light sources 61 to 6n can be normally performed, and can be easily diverted to a lighting device or the like that does not have the dimming circuit 2 as necessary without reducing its efficiency. Therefore, it has high versatility.

  Here, the function and effect of each diode connected in parallel to the first and second detection resistors R1 and R3 will be described. The operation of the diodes D9, D10, and D11 related to the second detection resistor is the same as that of the diodes D6, D7, and D8 related to the first detection resistor R1. The diodes D6, D7, and D8 related to the resistor R1 will be described as an example.

First, a series circuit of diodes D6 and D7 connected in parallel to the first detection resistor R1 will be described as follows. When the thyristor Q0 of the dimming circuit 2 is turned on in the negative half cycle, the drive current Ic ′ starts to flow through the drive circuits 71 to 7n. However, at this time, an abnormality occurs as a so-called inrush current in a short period after the thyristor Q0 is turned on. A large current may flow through. In the load circuit 8 in the present embodiment, a series circuit of diodes D6 and D7 (the forward drop voltage of each diode is Vf) is connected in parallel with the first detection resistor R1 (the resistance value is R). Therefore, when the value of Ic ′ is equal to or greater than (Vf × 2) / R, the diodes D6 and D7 are turned on, and a part of the inrush current branches and flows through the diodes D6 and D7. Thereafter, when the value of Ic ′ becomes equal to or less than (Vf × 2) / R, the conduction of the diodes D6 and D7 is cut off, and the current flowing through the first detection resistor R1 is caused to be V _BE / R by the normal operation of the load circuit 8. (However, V _BE is maintained at the base-emitter voltage of the first transistor Q1).

  Thus, in the lighting device 1, the inrush current flowing through the first detection resistor R1 can be made to flow through the series circuit of the diodes D6 and D7, and the current flowing through the first detection resistor R1 is made uniform. Resistance loss due to the inrush current of the drive circuits 71 to 7n connected to the subsequent stage of the load circuit 8 can be reduced.

In this embodiment, the diode for such inrush current is configured by using a series circuit of two diodes D6 and D7. However, the forward voltage drop of the diode is that of the first transistor Q1. The configuration is not limited to this configuration as long as the constant current control circuit 9 is normally operated after an inrush current is passed through the diode and is larger than the base-emitter voltage V _BE . For example, it may be configured by one or three or more diodes by appropriately selecting a diode connected in parallel to the first transistor Q1 and the first detection resistor R1. .

  Next, the diode D8 connected in parallel to the first detection resistor R1 will be described. When the thyristor Q0 of the dimming circuit 2 is turned on in the positive half cycle, the drive current Ic starts to flow through the drive circuits 71 to 7n. However, if the diode D8 is not connected in parallel to the first detection resistor R1, The drive current Ic flows through the first detection resistor R1 in the reverse direction (that is, in the direction opposite to the direction of the arrow shown as the positive direction of the drive current Ic ′ in the negative half cycle in FIG. 2). It will flow into the circuits 71-7n. As a result, a reverse base-emitter voltage due to the voltage across the first detection resistor R1 is applied to the first transistor Q1. In this embodiment, since the diode D8 is connected in parallel to the first detection resistor R1, the drive current Ic branches and flows to the diode D8, and thus the first transistor Q1 is protected from such a reverse voltage. In addition, it is possible to reduce the loss generated in the first detection resistor.

  As mentioned above, although this embodiment illustrates the illuminating device 1 containing the several light sources 61-6n and the drive circuits 71-7n as an example for showing the characteristic of this invention more clearly, this invention is shown. However, it goes without saying that the present invention can also be applied to an illumination device that has only one drive circuit and lights one illumination light source.

  Next, the illuminating device in 2nd Embodiment of this invention is demonstrated. The lighting device according to the second embodiment of the present invention is different from the lighting device 1 according to the first embodiment described above only in its load circuit, so illustration and detailed description thereof will be omitted. The difference between the load circuit and the load circuit 8 in the first embodiment will be mainly described. Moreover, in the following description, the component corresponding to the component shown in FIG.1 and FIG.2 is referred and attached | subjected with the same code | symbol.

(Second Embodiment)
As shown in FIG. 4, the load circuit 8a in this embodiment includes a third transistor Q5 included in the constant current control circuit 9b and a fourth transistor included in the variable current circuit 10b in the second circuit block 11b. Q6 is formed of a PNP transistor, and the first detection resistor of the first circuit block 11 and the second detection resistor of the second circuit block 11b are one common detection resistor as follows. The load circuit 8 is different from the load circuit 8 in the first embodiment in that it is constituted by R1.

  That is, in the load circuit 8a, one end of the common detection resistor R1 is connected to the positive terminal (+) of the output of the dimming circuit 2 together with the emitter terminal of the first transistor (NPN transistor) Q1 of the first circuit block 11. The other end is connected to the connection point between the one ends of the input sides of the rectifier circuits 31 to 3n together with the base terminal of the first transistor (NPN transistor) Q1 of the first circuit block 11. In addition, the emitter terminal of the third transistor (PNP transistor) Q5 of the second circuit block 11b is connected to one end of the detection resistor R1, and the base terminal of the third transistor Q5 is the other end of the detection resistor R1. Is connected to. In the second circuit block 11b, one end of the second resistance element R5 is connected to the negative terminal (− of the output of the dimming circuit 2 through the diode D16 together with the collector terminal of the fourth transistor (PNP transistor) Q6. The other end is connected to the base terminal of the fourth transistor Q6 together with the collector terminal of the third transistor Q5.

  In the present embodiment, due to the above difference, the common detection resistor R1 includes a series circuit composed of diodes D6 and D7 for inrush current branching in the negative half cycle, and an inrush current in the positive half cycle. A series circuit composed of diodes D14 and D15 for branching is connected in parallel so as to have opposite polarities.

By configuring the load circuit 8a in this way, the second circuit block 11b functions in the positive half cycle in the same manner as the second circuit block 11a of the load circuit 8 in the first embodiment, and the load circuit 8a The illuminating device using the above has the same effect as the illuminating device 1 in the first embodiment.
In addition, in the load circuit 8a in the present embodiment, the detection resistors R1 of the two sets of circuit blocks 11 and 11b are configured by one common resistive element, thereby reducing circuit components and reducing the cost of the lighting device. be able to.

  Next, the illuminating device in 3rd Embodiment of this invention is demonstrated. The illumination device in the third embodiment of the present invention is different from the illumination device 1 in the first embodiment described above only in its load circuit, and the load circuit is different from that described below. Since the load circuit 8a is the same as the load circuit 8a in the second embodiment except for the above, the following mainly describes the difference of the load circuit from the load circuit 8a in the second embodiment. Moreover, in the following description, the component corresponding to the component shown in FIG.1, FIG.2, and FIG.4 is attached | subjected and referred with the same code | symbol.

(Third embodiment)
As shown in FIG. 5, the load circuit 8b according to the present embodiment is the same as that described above in that the detection resistor common to the first circuit block 11 and the second circuit block 11b is constituted by the variable resistor VR1. Unlike the load circuit 8a in the second embodiment, the variable resistor VR1 can switch the resistance value according to the magnitude of the minimum holding current at which the dimming circuit 2 operates normally. FIG. 5 schematically shows a variable resistor VR1 that can be switched to several specific resistance values. However, the variable resistor VR1 in this embodiment has a resistance value within a specific range. It may be possible to switch continuously.

  The lighting device using the load circuit 8b according to the present embodiment exhibits the same effects as the lighting device using the load circuit 8a according to the second embodiment, and also according to various specifications of the dimming circuit 2. The load current flowing through the load circuit 8b can be optimized.

  As mentioned above, although this invention was demonstrated by preferable embodiment, this invention is not limited to embodiment mentioned above, A various deformation | transformation and application are possible within the range of the technical idea of this invention.

For example, in the first embodiment described above, the first to fourth transistors Q1 to Q4 included in the load circuit 8 may be configured by PNP transistors, and the first detection resistor R1 and the second detection resistor may be configured. One or both of the resistors R3 may be configured by the variable resistor VR1. In each embodiment, as a transistor included in each load circuit, not a bipolar transistor but a Pch-MOSFET or an Nch-MOSFET may be used depending on the configuration.
In the lighting device 1 according to the present embodiment, the rectifier circuits 31 to 3n are full-wave rectifier circuits configured as diode bridges, but are not limited thereto, and may be other rectifier circuits. .

1: lighting device, 2: dimming circuit, 31-3n: rectifier circuit, 41-4n: smoothing circuit, 51-5n: lighting circuit, 61-6n: light source for illumination (load), 71-7n: drive circuit, 8, 8a, 8b: load circuit, 9, 9a, 9b: constant current control circuit, 10, 10a, 10b: variable current circuit, 11: first circuit block, 11a, 11b: second circuit block, C1: Capacitors, D1 to D16: Diodes, Ic, Ic ′: Sum of currents flowing through each drive circuit (drive current), Iv, Iv ′: Load current (collector current) of the load circuit, Io, Io ′: Dimming circuit Current flowing, Q0: bidirectional three-terminal thyristor (thyristor), Q1: first transistor, Q2: second transistor, Q3, Q5: third transistor, Q4, Q6: fourth transistor, R1: first Detection Anti (common detection resistor), R2: a first resistor element, R3: a second detection resistor, R4, R5: a second resistive element, Vac: commercial AC power source, VR1: a variable resistor

Claims (4)

One dimming circuit that controls the phase of current supplied to one or more illumination light sources by controlling the conduction angle of alternating current supplied from a commercial AC power source, and the one or more illumination light sources, respectively In the lighting device including one or more drive circuits for driving, each of the drive circuits includes a rectifier circuit that rectifies an AC voltage output from the dimming circuit, and a DC voltage output from the rectifier circuit. A smoothing circuit for smoothing; and a lighting circuit for causing the illumination light source to emit light in accordance with the voltage smoothed by the smoothing circuit; and between the dimming circuit and the one or more drive circuits. A load circuit that maintains a minimum holding current at which the dimming circuit operates normally ,
The load circuit detects a current flowing through the dimming circuit and outputs a control signal for inducing a shortage of the minimum holding current of the dimming circuit, and a control from the constant current control circuit And two sets of circuit blocks each having a variable current circuit for inputting a signal and causing a shortage of the minimum holding current of the dimming circuit to flow, each of the circuit blocks being bidirectionally phase-controlled by the dimming circuit A minimum holding current at which the dimming circuit operates normally with respect to currents in different directions among the currents is maintained . The lighting device according to claim 1 , wherein the constant current control circuit includes a detection resistor that detects a current flowing through the dimming circuit and a semiconductor element that transmits the control signal. The lighting device according to claim 2 , wherein the detection resistor is common to the two sets of circuit blocks. The detection resistor lighting device according to claim 2 or 3, wherein the light control circuit is at a minimum holding possible resistance switching in accordance with the magnitude variable resistance of the current operating normally.

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