JP5239138B2 - LED lighting device - Google Patents

Description

  The present invention relates to an LED lighting device and an LED board module using a light emitting diode as a light emitting part.

2. Description of the Related Art Conventionally, LED lighting devices that use light emitting diodes as light emitting units are known that control lighting of light emitting diodes with a constant current (for example, see Patent Document 1).
JP-A-6-328882

In such an LED lighting device, when a light emitting section is configured by connecting a plurality of circuits in which one or a plurality of light emitting diodes (hereinafter referred to as LEDs) are connected in series, the forward voltage of each LED is manufactured. Due to the above variation, there arises a problem that the lighting currents flowing through the branches in the parallel circuit are not uniform. That is, there is a problem that current is concentrated on a branch having a low forward voltage.
In addition, there is a problem that heat is generated in a branch having a low forward voltage because the current flowing therethrough increases. Since the LED is a semiconductor, the forward voltage has a negative temperature characteristic. For this reason, in the branch having a low forward voltage, the forward voltage is further reduced by heat generation, and the flowing current is further increased.

Due to such a phenomenon, in the LED lighting device in which the light emitting unit is configured by connecting a plurality of circuits in which one or a plurality of LEDs are connected in series in parallel, the current is more concentrated on the branch having a low forward voltage. There is a problem that the current flowing through the branch cannot be uniformly controlled.
In the present invention, when a light emitting unit is configured by connecting a plurality of circuits in which one or a plurality of LEDs are connected in series, a lighting current flowing through each branch can be uniformly controlled using a constant current power source. An LED lighting device is provided.

  The present invention can uniformly control the lighting current flowing in each branch using a constant voltage power supply when a light emitting unit is configured by connecting a plurality of circuits in which one or a plurality of LEDs are connected in series in parallel. An LED lighting device is provided.

  The present invention is suitable for the case where a light emitting unit is configured by connecting a plurality of circuits in which one or a plurality of LEDs are connected in series in parallel, and is also suitable for uniformly controlling the lighting current flowing through each branch. Provide modules.

  In the present invention, when a light emitting unit is configured by connecting a plurality of circuits in which one or a plurality of LEDs are connected in series, a lighting current flowing through each branch can be uniformly controlled using a constant current power source. And the LED lighting device which can make a light emission part a simple structure is provided.

  In the present invention, in which one or a plurality of circuits in which LEDs are connected in series are connected in parallel to form a light emitting section, the lighting current flowing in each branch is made more uniform and uniform using a constant current power source. Provided is an LED lighting device that can be controlled.

  In the present invention, a circuit in which one or a plurality of LEDs are connected in series is connected in parallel by changing the number of light emitting diodes to be connected, and a light emitting unit is configured. Provided is an LED lighting device that can be accurately and uniformly controlled.

  In the present invention, a circuit in which one or a plurality of LEDs are connected in series is connected in parallel by changing the number of light emitting diodes to be connected, and a light emitting unit is configured. Provided is an LED lighting device that can be accurately and uniformly controlled and has a simple configuration.

The present invention relates to an LED light emitting unit in which a DC power source, one or a plurality of light emitting diodes connected in series, and a series circuit of a transistor and a resistance element are connected in parallel by varying the number of light emitting diodes connected respectively. comprising a said connected the base of the transistor of the series circuits to each other, of the respective series circuits, in LED lighting device shorted collector of the transistor of the largest number series circuit of the light emitting diodes connected in series, a base .
Also in this case, since the emitter currents of the transistors in each series circuit are equal, the collector current, that is, the currents flowing through the light emitting diodes in each series circuit are equal.

  According to the present invention, when a light emitting unit is configured by connecting a plurality of circuits in which one or a plurality of LEDs are connected in series in parallel, the lighting current flowing through each branch is made uniform using a constant current power source. An LED lighting device that can be controlled can be provided.

  According to the present invention, when a light emitting unit is configured by connecting a plurality of circuits in which one or a plurality of LEDs are connected in series in parallel, the lighting current flowing through each branch is made uniform using a constant voltage power supply. An LED lighting device that can be controlled can be provided.

  According to the present invention, it is suitable for the case where a light emitting unit is configured by connecting a plurality of circuits in which one or a plurality of LEDs are connected in series in parallel, and also suitable for uniformly controlling the lighting current flowing through each branch. An LED substrate module can be provided.

  According to the present invention, in the case where a light emitting unit is configured by connecting a plurality of circuits in which one or a plurality of LEDs are connected in series, a lighting current flowing through each branch is made uniform using a constant current power source. It is possible to provide an LED lighting device that can be controlled and that has a simple configuration of the light emitting unit.

  According to the present invention, in the case where a light emitting unit is configured by connecting a plurality of circuits in which one or a plurality of LEDs are connected in series, a lighting current flowing through each branch is more accurately measured using a constant current power source. It is possible to provide an LED lighting device that can be controlled well and uniformly.

  According to the present invention, a circuit in which one or a plurality of LEDs are connected in series is connected in parallel by changing the number of light emitting diodes to be connected to form a light emitting unit. It is possible to provide an LED lighting device that can accurately and uniformly control the above.

  According to the present invention, a circuit in which one or a plurality of LEDs are connected in series is connected in parallel by changing the number of light emitting diodes to be connected to form a light emitting unit. Can be accurately and uniformly controlled, and an LED lighting device having a simple configuration can be provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
As shown in FIG. 1, a known constant current power source 2 is connected to a commercial AC power source 1, and a constant current is output from the constant current power source 2. For example, three LED board modules 3-1, 3-2, and 3-3 are connected in parallel to the output terminal of the constant current power supply 2, and a bias circuit 4 is connected in parallel.

  For example, as shown in FIG. 2, each of the LED board modules 3-1, 3-2, and 3-3 has a current control circuit provided with a control electrode in series with a circuit in which a plurality of LEDs 5 are connected in series. The current control circuit includes, for example, an NPN bipolar transistor 6 and a current detection resistor element 7 connected in series to the emitter of the transistor 6. The base of the transistor 6 is used as a control electrode.

  The anode side end of the circuit in which the LEDs 5 are connected in series is connected to one power supply terminal 8a, the end of the current detection resistor element 7 not connected to the transistor 6 is connected to another power supply terminal 8b, and the transistor The base of 6 is connected to the control terminal 8c. The power supply terminal 8 a is connected to the positive output terminal of the constant current power supply 2, the power supply terminal 8 b is connected to the negative output terminal of the constant current power supply 2, and the control terminal 8 c is connected to the bias circuit 4.

  In each of the LED board modules 3-1, 3-2, and 3-3, circuit elements constituting the circuit shown in FIG. 2 are arranged on the board 11 as shown in FIG. That is, the board 11 has the LEDs 5 arranged in a row at a predetermined interval in the center, and the three terminals of the power terminals 8a and 8b and the control terminal 8c are arranged on one end side. The transistor 6 and the current detection resistor element 7 are arranged at predetermined positions on the substrate 11. Each circuit element is electrically connected by a wiring pattern. On both sides of the substrate 11, mounting holes 12a and 12b are formed when the substrate 11 is fixed to an instrument.

  In such a configuration, the bipolar transistor 6 disposed in each of the substrate modules 3-1, 3-2, 3-3 is supplied with a constant bias current from the bias circuit 4 to the base via the control terminal 8c. Power on. As a result, a lighting current flows through the LED circuits arranged in the respective board modules 3-1, 3-2, 3-3, and each LED 5 emits light.

  The lighting current flows through the current detection resistor element 7, and thereby the emitter potential of the bipolar transistor 6 is determined. When the lighting current increases, the emitter potential increases, and the bipolar transistor 6 operates in a direction that suppresses the degree of conduction. When the lighting current is reduced, the emitter potential is lowered, and the bipolar transistor 6 operates in a direction to increase the degree of conduction.

  In this way, when the constant current power supply 2 is used, the lighting currents flowing through the LEDs 5 of the board modules 3-1, 3-2, and 3-3, that is, the LEDs 5 of the branches, are controlled to be uniform. Is done. That is, even if there is a variation in the forward voltage of each LED 5 and there is a difference in the total forward voltage of the LED circuits in each of the board modules 3-1, 3-2, 3-3, a lighting current is generated by each bipolar transistor 6. Is controlled to be uniform. As a result, the LEDs 5 of the board modules 3-1, 3-2, and 3-3 emit light substantially uniformly.

  In addition, each of the board modules 3-1, 3-2, and 3-3 is designed to be compact by arranging circuit elements such as the LED 5 and the transistor 6 on the board 11, so that the board modules can be easily attached to the equipment. Become. In addition, it is possible to easily assemble the board module 3-1, 3-2, and 3-3 that are connected in parallel to form a light emitting unit. Furthermore, since the three terminals of the power supply terminals 8a and 8b and the control terminal 8c are arranged at the end of the substrate 11, the connection to the constant current power supply 2 and the connection to the bias circuit 4 can be facilitated.

  In this embodiment, the circuit of each of the substrate modules 3-1, 3-2, and 3-3 is connected to a circuit in which a plurality of LEDs 5 are connected in series, and a bipolar transistor 6 and a current detection resistor element 7 are connected in series. Although what was comprised by the circuit which connected the circuit in series was described, it is not limited to this.

  For example, as shown in FIG. 4, a bias resistance element 9 is further connected between the power supply terminal 8a and the control terminal 8c in the configuration of FIG. 2, and the bias resistance element is connected between the control terminal 8c and the power supply terminal 8b. A circuit configuration in which the resistance element 10 is connected may be used.

Further, as shown in FIG. 5, a circuit in which a plurality of LEDs 5-1 are connected in series, a series circuit in which an NPN-type bipolar transistor 6-1 and a current detection resistor element 7-1 are connected in series, and a plurality of The circuit configuration may include a parallel circuit of a series circuit in which the NPN bipolar transistor 6-2 and the current detection resistor element 7-2 are connected in series to a circuit in which the LEDs 5-2 are connected in series. The parallel circuit is not limited to a circuit in which a plurality of LEDs 5 are connected in series, and two series circuits in which an NPN bipolar transistor 6 and a current detection resistor element 7 are connected in series are connected in parallel. Alternatively, three or more connected in parallel may be used.
Furthermore, the number of LEDs used in each series circuit is not limited to a plurality, and may be one.

(Second Embodiment)
In addition, the same code | symbol is attached | subjected to the part same as 1st Embodiment mentioned above, and detailed description is abbreviate | omitted. As shown in FIG. 6, a known constant voltage power supply 12 is connected to the commercial AC power supply 1, and a constant voltage is output from the constant voltage power supply 12.

  For example, three LED board modules 3-1, 3-2, and 3-3 are connected in parallel to the output terminal of the constant voltage power supply 12, and a reference voltage generating circuit 13 is connected in parallel.

  The reference voltage generation circuit 13 generates a constant reference voltage and applies it to the control terminals 8c of the LED board modules 3-1, 3-2, and 3-3. The circuit configuration of each of the LED board modules 3-1, 3-2, and 3-3 is as shown in FIG. In this case, the circuit configurations of the LED board modules 3-1, 3-2, and 3-3 are not limited to those shown in FIG. 2, but may be the configurations shown in FIGS.

  In such a configuration, the bipolar transistor 6 arranged in each of the substrate modules 3-1, 3-2, 3-3 has a constant reference voltage from the reference voltage generating circuit 13 to the base via the control terminal 8c. Applied and energized. As a result, a lighting current flows through the LED circuits in the branches arranged in the respective board modules 3-1, 3-2, 3-3, and each LED 5 emits light.

  The lighting current flows through the current detection resistor element 7, and thereby the emitter potential of the bipolar transistor 6 is determined. When the lighting current increases, the emitter potential increases, and the bipolar transistor 6 operates in a direction that suppresses the degree of conduction. When the lighting current is reduced, the emitter potential is lowered, and the bipolar transistor 6 operates in a direction to increase the degree of conduction.

  Even when the constant voltage power supply 12 is used in this way, the lighting currents flowing through the LEDs 5 of the board modules 3-1, 3-2, and 3-3, that is, the LEDs 5 of the branches, are controlled to be uniform. The That is, even if there is a variation in the forward voltage of each LED 5 and there is a difference in the total forward voltage of the series circuit of LEDs 5 in each of the board modules 3-1, 3-2, 3-3, the bipolar transistors 6 The lighting current is controlled to be uniform. As a result, the LEDs 5 of the board modules 3-1, 3-2, and 3-3 emit light substantially uniformly.

(Third embodiment)
As shown in FIG. 7, a constant current power supply 20 is connected to the commercial AC power supply 1, and an LED light emitting unit 30 is connected to the constant current power supply 20.

  The constant current power source 20 has an input terminal of a full-wave rectifier circuit 21 connected to the commercial AC power source 1. A smoothing capacitor 22 is connected between the output terminals of the full-wave rectifier circuit 21, and a capacitor 25 is connected in parallel to the smoothing capacitor 22 via a MOS FET (field effect transistor) 23 and an inductor 24 in series. ing. A diode 26 is connected in parallel to the capacitor 25 via the inductor 24 with a reverse polarity.

  The constant current power source 20 has a connection point between the inductor 24 and one end of the capacitor 25 connected to the positive output terminal 20a, and the other end of the capacitor 25 connected to the negative output terminal 20b via a resistance element 27 in series. Connected to. The voltage generated at the connection point between the resistance element 27 and the negative output terminal 20b is input to one of the error amplifiers 28 at the input terminal. A reference voltage Vref is input to the other input terminal of the error amplifier 28.

  The error amplifier 28 amplifies an error between the reference voltage Vref and the voltage generated between both ends of the resistance element 27, and supplies the amplified error to the drive unit 29 that drives the FET 23 for switching. The drive unit 29 drives the FET 23 on and off, and controls the on-duty of the FET 23 so that a constant current is output from the output terminals 20a and 20b by the error output from the error amplifier 28. ing.

  The LED light emitting unit 30 includes a circuit in which a plurality of LEDs 31-1 are connected in series and a series circuit of a resistance element 32-1, and a circuit in which a plurality of LEDs 31-2 are connected in series and a series circuit of a resistance element 32-2. A series circuit of a plurality of LEDs 31-3 connected in series and a resistance element 32-3,..., A circuit of a plurality of LEDs 31-n connected in series and a series circuit of a resistance element 32-n in parallel with each other Connected and configured. That is, each series circuit constitutes a branch path.

  The anode side end of the circuit in which the LEDs are connected in series is connected to one input terminal 30a connected to the positive output terminal 20a of the constant current power supply 20, and the LEDs of the resistance elements 32-1 to 32-n. The other end of the constant current power supply 20 is connected to the other input terminal 30b connected to the negative output terminal 20b.

  The LED light emitting unit 30 adjusts the resistance values of the resistance elements 32-1 to 32-n of each series circuit in advance. That is, a predetermined current is supplied to a plurality of LEDs for each series circuit to light them in advance, a series circuit having the highest forward voltage is found, and the voltage across the series circuit is set as a reference voltage. In other series circuits, the resistance value of each resistance element is adjusted so that the voltage across the series circuit becomes equal to the reference voltage when a predetermined current is passed.

  In such a configuration, a constant current is supplied from the constant current power supply 20 to the LED light emitting unit 30. The LED light emitting unit 30 includes a circuit in which a plurality of LEDs 31-1 are connected in series, a circuit in which a plurality of LEDs 31-2 are connected in series, a circuit in which a plurality of LEDs 31-3 are connected in series, ..., a plurality of LEDs 31-n. Even if the forward voltages of the circuits connected in series are different, the voltage across both terminals when a predetermined current is passed is equal to the reference voltage for the entire series circuit connected with the resistance elements 32-1 to 32-n. As described above, the resistance values of the resistance elements 32-1 to 32-n are adjusted.

  Accordingly, a series circuit of a circuit in which a plurality of LEDs 31-1 are connected in series and a resistance element 32-1, a series circuit of a circuit in which a plurality of LEDs 31-2 are connected in series and a resistance element 32-2, and a plurality of LEDs 31- 3 is a series circuit of a resistance element 32-3 and a series circuit of a plurality of LEDs 31-n and a series circuit of a resistance element 32-n, that is, lighting that flows in each branch The current becomes uniform.

As a result, the plurality of LEDs 31-1, the plurality of LEDs 31-2, the plurality of LEDs 31-3,..., The plurality of LEDs 31-n emit light equally, and the LED light emitting unit 30 performs a good light emitting operation. Will do. Moreover, since the LED light emitting unit 30 uses only a plurality of resistance elements 32-1 to 32-n in addition to a plurality of LEDs, the configuration is simple.
In this embodiment, a circuit in which a plurality of LEDs are connected in series to each branch is used. However, one LED may be used for each branch.

(Fourth embodiment)
In addition, this embodiment describes the modification of an LED light emission part. As the power source, the same one as the constant current power source 20 used in the third embodiment is used.
As shown in FIG. 8, the LED light emitting unit 40 of this embodiment includes a circuit and a transistor in which a plurality of LEDs 31-1 are connected in series, for example, an NPN bipolar transistor 41-1 and an emitter of the bipolar transistor 41-1. A series circuit with a resistance element 42-1 connected to the circuit, a circuit with a plurality of LEDs 31-2 connected in series and a transistor, for example, an NPN bipolar transistor 41-2 and a resistance element connected to the emitter of the bipolar transistor 41-2 42-2, a circuit in which a plurality of LEDs 31-3 are connected in series, and a transistor, for example, an NPN bipolar transistor 41-3 and a resistance element 42-3 connected to the emitter of the bipolar transistor 41-3. A series circuit, a circuit in which a plurality of LEDs 31-n are connected in series and a transistor, for example, an NPN type bipolar Connecting the series circuit of the La transistors 41-n and the resistance element 42-n connected to the emitter of the bipolar transistor 41-n in parallel with each other. That is, each series circuit constitutes a branch path. Each of the resistance elements 42-1 to 42-n is a current detection resistor.

  The anode side end of the circuit in which the LEDs are connected in series is connected to one input terminal 40a connected to the positive output terminal of a constant current power source (not shown), and each of the resistance elements 42-1 to 42-n. The other end not connected to the transistor is connected to the other input terminal 40b connected to the negative output terminal of the constant current power source. Diodes 43-1 to 43-n are connected between the bases and collectors of the bipolar transistors 41-1 to 41-n, respectively, with the anode terminal as the base side.

  A bias circuit composed of a series circuit of resistance elements 44 and 45 is connected between the input terminals 40a and 40b. The connection point of the resistance elements 44 and 45 is connected to the bases of the bipolar transistors 41-1 to 41-n.

  The LED light emitting unit 40 is lit by supplying a predetermined current to the LED in advance for each branch, finds a branch having the highest forward voltage, and only the bipolar transistor of the branch operates in the saturation region. The resistance values of the resistance elements 44 and 45 of the bias circuit and the resistance values of the resistance elements 42-1 to 42-n are set.

  For example, the LED light emitting unit 40 has a configuration in which 16 series circuits each having a circuit in which 16 LEDs are connected in series are connected in parallel, and the LED light emitting unit 40 is supplied with a constant current of 400 mA from a constant current power source (not shown). When a current is supplied, a lighting current of 25 mA flows through each branch.

  In this LED light emitting unit 40, the resistance value of the resistance element 44 is set to 15 KΩ, the resistance value of the resistance element 45 is set to 2.2 KΩ, the resistance values of the resistance elements 42-1 to 42-n are set to 22Ω, and the forward voltage is set to When the highest branch bipolar transistor operates in the saturation region, the other 15 branch bipolar transistors operate in the active region.

  In such a configuration, for example, if the forward voltage of a circuit in which a plurality of LEDs 31-n are connected in series is the highest, only the bipolar transistor 41-n connected to this circuit operates in the saturation region, The other 15 branches of bipolar transistors 41-1˜ operate in the active region.

  For example, assuming that there are three LED series circuits A, B, C, connected in parallel, the forward voltage VF of the A circuit is 10 V, the forward voltage VF of the B circuit is 9 V, and the forward voltage VF of the C circuit. Is 8V. Further, it is assumed that the current amplification factor hFE of the bipolar transistor connected to the LED series circuit is 100.

  A bias current of 1 mA is supplied to the base terminals of the three bipolar transistors connected to the three LED series circuits. This value is sufficiently larger than 1 / hFE: 0.6 mA of the full load current of 60 mA, so that all bipolar transistors can be saturated if the three LED series circuits are balanced.

  A current of 60 mA is collectively supplied from a constant current source to three LED series circuits connected in parallel. In this case, the supplied current flows in a divided manner to A, B, C, and three LED series circuits. Since the forward voltage VF of the LED series circuit of A is the highest, the collector-emitter voltage of the bipolar transistor of the A circuit is the lowest, and between the collector and emitter of the bipolar transistors of the B and C circuits is larger than that of the A circuit. Voltage is applied. Since the collector-emitter voltage required for the active operation is secured, the B circuit and the C circuit perform the active state operation, and a base current (about 0.4 mA) of 1 / hFE of the collector current flows into the base terminal.

  Of the bias current supplied from the bias circuit, all of the current (about 0.6 mA) that does not flow into the B circuit and the C circuit flows into the base of the A circuit and deeply saturates the bipolar transistor of the A circuit. Due to the deep saturation, the collector-emitter voltage drops to a low value of about 0.2V, for example.

  As described above, when the bipolar transistor of the LED series circuit having the highest forward voltage is saturated, the base potential is determined, and the bipolar transistors of the other LED series circuits remain active and subordinately operate as a constant current circuit. To do.

  A saturated bipolar transistor has a larger base current than other bipolar transistors, and therefore the base-emitter voltage is slightly higher than other active bipolar transistors. Therefore, the voltage at the connection point between the emitter of the bipolar transistor and the resistance element that is saturated is slightly lower than the voltage at the connection point between the emitter and the resistance element of another bipolar transistor that operates in an active state.

  As a result, the LED current of the circuit connected with the saturated bipolar transistor is slightly lower than the LED current of the other circuits. Therefore, the current imbalance can be improved by designing the resistance value of the resistor element so as to increase the voltage at the connection point between the emitter of the bipolar transistor and the resistor element.

Under the operating principle as described above, the burden voltage of the constant current circuit is kept at the minimum voltage (the base of the bipolar transistor, the saturation voltage between the emitters + the emitter resistance = the end voltage of the resistance element), so that the loss is reduced. The operating point is automatically determined so as to be minimized, so that the system efficiency can be kept high.
Here, the description has been made assuming that the supply current from the constant current source is 60 mA. However, if the circuit constants are set so that the bias current is sufficiently supplied, the same current can be obtained for any supply current. Balance operation is performed.

  Thus, in this embodiment, only the bipolar transistor 41-n operates in the saturation region, and the other 15 branch bipolar transistors 41-1˜ operate in the active region. As a result, control is performed so that the voltages across both branches of the LED light emitting unit 40 are equal, and the lighting current flowing in each branch becomes uniform with high accuracy. As a result, the plurality of LEDs 31-1, the plurality of LEDs 31-2, the plurality of LEDs 31-3,..., The plurality of LEDs 31-n emit light equally, and the LED light emitting unit 30 performs a good light emitting operation. Will do.

In addition, since the operating point of the bipolar transistor is automatically determined in each branch so that the loss is minimized, the system efficiency can be increased.
In this embodiment, a circuit in which a plurality of LEDs are connected in series to each branch is used. However, one LED may be used for each branch.

(Fifth embodiment)
This embodiment describes a modification in which the number of light emitting diodes connected to each branch is different in the LED light emitting section.
As shown in FIG. 9, a constant voltage power supply 50 is connected to the commercial AC power supply 1. Although a constant voltage power supply is used here, the present invention is not limited to this, and a constant current power supply or a simple DC power supply may be used.

  An LED light emitting unit 51 is connected to the constant voltage power source 50. The LED light emitting unit 51 includes a circuit composed of one light emitting diode 52, a circuit formed by connecting two light emitting diodes 53, 54 in series, and a circuit formed by connecting three light emitting diodes 55, 56, 57 in series. The branch circuits are connected in parallel to each other through the leveling circuit 58, and the parallel circuits are connected to the output terminal (+) 50a and the output terminal (-) 50b of the constant voltage power supply 50. Although the number of light emitting diodes to be connected is one, two, or three here, it is needless to say that the present invention is not limited to this.

  Specifically, as shown in FIG. 10, the LED light emitting unit 51 includes a series circuit of the light emitting diode 52, an NPN bipolar transistor 59, and a resistance element 60, and the light emitting diodes 53, 54 and an NPN bipolar. A series circuit of a transistor 61 and a resistance element 62, a series circuit of the light emitting diodes 55, 56, 57, an NPN bipolar transistor 63 and a resistance element 64 are connected in parallel to each other, and the parallel circuit is connected to the constant voltage power supply 50. Are connected to the output terminal (+) 50a and the output terminal (-) 50b.

  A first control circuit 65 that controls the base current of the transistor 59 is connected in parallel to the series circuit of the light emitting diode 52, the transistor 59, and the resistance element 60. The first control circuit 65 includes an NPN-type bipolar transistor 66. The collector and base of the transistor 66 are connected to the base of the transistor 59, and a resistance element 67 is connected in series to the output terminal (+). The emitter is connected to the output terminal (−) through a resistance element 68 in series.

  A second control circuit 69 for controlling the base current of the transistor 61 is connected in parallel to a series circuit of the light emitting diodes 53 and 54, the transistor 61, and the resistance element 62. The second control circuit 69 includes an NPN-type bipolar transistor 70. The collector and base of the transistor 70 are connected to the base of the transistor 61, and a resistor element 71 is connected in series to the output terminal (+). The emitter is connected to the output terminal (−) through a resistance element 72 in series.

  A third control circuit 73 for controlling the base current of the transistor 63 is connected in parallel to the series circuit of the light emitting diodes 55, 56, 57, the transistor 63 and the resistance element 64. The third control circuit 73 includes an NPN-type bipolar transistor 74. The collector and base of the transistor 74 are connected to the base of the transistor 63, and a resistor element 75 is connected in series to the output terminal (+). The emitter is connected to the output terminal (−) through a resistance element 76 in series.

  In the LED light emitting section 51, the transistors 59, 61, 63, 66, 70, 74 and the resistance elements 60, 62, 64, 67, 68, 71, 72, 75, 76 constitute the leveling circuit 58. ing.

  In the leveling circuit 58, the resistance value of the resistance element 60 is set according to the forward voltage of the series circuit of the light emitting diode 52 and the transistor 59, and the resistance value of the resistance element 62 is set to the light emitting diodes 53 and 54 and the transistor. The resistance value of the resistor element 64 is set according to the forward voltage of the series circuit of the light emitting diodes 55, 56, and 57 and the transistor 63. Accordingly, the resistance values of the resistance elements 60, 62, and 64 vary depending on the number of light emitting diodes to be connected. Further, the resistance elements 67, 71, 75 of the control circuits 65, 69, 73 are equal to each other, and the resistance elements 68, 72, 76 are also equal to each other.

  In such a configuration, when energization of the first control circuit 65 is started and the transistor 66 operates, the transistor 59 operates with the base current controlled. At this time, the transistor 59 is controlled so that the emitter current of the transistor 66 and the emitter current of the transistor 59 are equal. Thus, a constant current flows through the light emitting diode 52 via the transistor 59 and the resistance element 60.

  Further, when energization of the second control circuit 69 is started and the transistor 70 is operated, the transistor 61 is operated by controlling the base current. At this time, the transistor 61 is controlled so that the emitter current of the transistor 70 and the emitter current of the transistor 61 are equal. Thus, a constant current flows through the transistor 61 in the series circuit of the light emitting diodes 53 and 54.

  When the third control circuit 73 is energized and the transistor 74 operates, the transistor 63 operates with the base current controlled. At this time, the transistor 63 is controlled so that the emitter current of the transistor 74 and the emitter current of the transistor 63 are equal. Thus, a constant current flows through the transistor 63 in the series circuit of the light emitting diodes 55, 56, and 57.

  Since the control circuits 65, 69, and 73 have the same circuit configuration, the emitter currents of the transistors 59, 61, and 63 controlled by the control circuits 65, 69, and 73 are equal to each other. The constant current flowing through 52, the constant current flowing through the series circuit of the light emitting diodes 53, 54, and the constant current flowing through the series circuit of the light emitting diodes 55, 56, 57 are equal. In this way, it is possible to accurately and uniformly control the lighting currents of the light emitting diodes flowing through the respective series circuits that are branches.

(Sixth embodiment)
This embodiment also describes a modification in which the number of light emitting diodes connected to each branch is different in the LED light emitting section. The same parts as those of the fifth embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 11, the LED light emitting unit 81 of this embodiment uses a leveling circuit 581 that uses only the first control circuit 65 as the leveling circuit. That is, the leveling circuit 581 connects the collector and base of the transistor 66 of the first control circuit 65 to the bases of the transistors 59, 61, and 63 of each series circuit to which a light emitting diode is connected. . Other configurations are the same as those of the fifth embodiment described above.

  Even in such a configuration, when energization of the first control circuit 65 is started and the transistor 66 operates, the transistors 59, 61, and 63 operate by controlling the base current, respectively. At this time, the transistors 59, 61, and 63 are controlled so that the emitter current of the transistor 66 and the emitter currents of the transistors 59, 61, and 63 are equal. Thus, a constant current flows to the light emitting diode 52 via the transistor 59 and the resistance element 60, and a constant current flows to the series circuit of the light emitting diodes 53, 54 via the transistor 61, and the light emitting diodes 55, 56, 57 are connected in series. In the circuit, a constant current flows through the transistor 63, and currents equal to each other flow.

Therefore, also in this embodiment, similarly to the fifth embodiment described above, the lighting current of the light emitting diode flowing in each series circuit as a branch can be accurately and uniformly controlled.
In this embodiment, since the control circuit can be made common to each series circuit, the configuration of the leveling circuit 581 is simplified.

(Seventh embodiment)
This embodiment also describes a modification in which the number of light emitting diodes connected to each branch is different in the LED light emitting section. The same parts as those of the fifth embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 12, the LED light emitting unit 91 of this embodiment uses a leveling circuit 582 using a common control circuit 92 as a leveling circuit. The control circuit 92 connects a series circuit of a resistance element 93 and a resistance element 94 between the output terminal (+) 50a and the output terminal (−) 50b. The emitter of a PNP bipolar transistor 95 is connected to the connection point. The transistor 95 has a base connected to the output terminal (−) 50b via a Zener diode 96, and a collector connected to the bases of the transistors 59, 61, and 63 of each series circuit. Other configurations are the same as those of the fifth embodiment described above.

  Even in such a configuration, when energization of the control circuit 92 is started, the transistor 95 operates, and a constant voltage is applied to the bases of the transistors 59, 61, and 63 through the transistor 95. As a result, the transistors 59, 61, and 63 operate, and the transistors 59, 61, and 63 are controlled so that their emitter currents are equal to each other. Thus, a constant current flows to the light emitting diode 52 via the transistor 59 and the resistance element 60, and a constant current flows to the series circuit of the light emitting diodes 53, 54 via the transistor 61, and the light emitting diodes 55, 56, 57 are connected in series. In the circuit, a constant current flows through the transistor 63, and currents equal to each other flow.

Therefore, also in this embodiment, similarly to the fifth embodiment described above, the lighting current of the light emitting diode flowing in each series circuit as a branch can be accurately and uniformly controlled.
Also in this embodiment, since the control circuit can be made common to each series circuit, the configuration of the leveling circuit 582 is simplified.

(Eighth embodiment)
This embodiment also describes a modification in which the number of light emitting diodes connected to each branch is different in the LED light emitting section. The same parts as those of the fifth embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 13, the LED light emitting unit 101 according to this embodiment connects the bases of the transistors 59, 61, and 63 of each series circuit to each other as a leveling circuit, and the connected light emitting diode load is the heaviest series. The circuit, that is, a leveling circuit 583 in which the collector and base of the transistor 63 in a series circuit in which three light emitting diodes 55, 56, and 57 are connected is short-circuited is used.

  In such a configuration, first, the same base current flows from the collector of the transistor 63 connected to the series circuit of the light emitting diodes 55, 56, and 57 to the base of each of the transistors 59, 61, and 63 via the short circuit. The same emitter current flows through each transistor 59, 61, 63.

  Thus, a constant current flows to the light emitting diode 52 via the transistor 59 and the resistance element 60, and a constant current flows to the series circuit of the light emitting diodes 53, 54 via the transistor 61, and the light emitting diodes 55, 56, 57 are connected in series. In the circuit, a constant current flows through the transistor 63, and currents equal to each other flow.

Therefore, also in this embodiment, similarly to the fifth embodiment described above, the lighting current of the light emitting diode flowing in each series circuit as a branch can be accurately and uniformly controlled.
In this embodiment, since a separate control circuit is not used, the configuration of the leveling circuit 583 is further simplified.

The block diagram which shows the whole structure which concerns on the 1st Embodiment of this invention. The figure which shows the circuit example of the LED board module in the embodiment. The figure which shows the external appearance of the LED board module in the embodiment. The figure which shows the other circuit example of the LED board module in the embodiment. The figure which shows the other circuit example of the LED board module in the embodiment. The block diagram which shows the whole structure which concerns on the 2nd Embodiment of this invention. The circuit diagram which shows the whole structure which concerns on the 3rd Embodiment of this invention. The circuit diagram of the LED light emission part which concerns on the 4th Embodiment of this invention. The block diagram which shows the whole structure which concerns on the 5th Embodiment of this invention. The circuit diagram of the LED light emission part which concerns on the same embodiment. The circuit diagram of the LED light emission part which concerns on the 6th Embodiment of this invention. The circuit diagram which shows the whole structure which concerns on the 7th Embodiment of this invention. The circuit diagram of the LED light emission part which concerns on the 8th Embodiment of this invention.

Explanation of symbols

  2 ... constant current power source, 3-1, 3-2, 3-3 ... LED board module, 4 ... bias circuit, 5 ... LED (light emitting diode), 6 ... bipolar transistor, 7 ... current detection resistor element, 8a, 8b ... Power supply terminal, 8c ... Control terminal.

Claims (1)

DC power supply,
One or a plurality of light emitting diodes connected in series, a series circuit of a transistor and a resistance element, each comprising a plurality of LED light emitting units connected in parallel with different numbers of light emitting diodes connected,
The bases of the transistors of each series circuit are connected to each other, the collectors and bases of the transistors of the series circuit having the largest number of light-emitting diodes connected in series among the series circuits are short-circuited, and the emitters of the transistors of the series circuits An LED lighting device characterized in that currents are equal to each other.

Images