JP5006856B2 - Light emitting device and lighting device - Google Patents

Description

  The present invention relates to a light emitting device having a light source such as a light emitting diode and a lighting device including the light emitting device.

  In a conventional light-emitting device, a drive circuit that drives a light-emitting diode that is a light source emits light by combining a plurality of single-color light-emitting diodes in order to obtain light of a desired color temperature, and corresponds to the current of each light-emitting diode. A drive circuit is provided for driving (for example, see Patent Document 1). Usually, since the required current of the light emitting diode differs depending on the light emitting color, the light emitting diodes of the same light emitting color are connected in series, and a drive circuit is provided for each.

JP 2002-244103 (paragraph number 0009 and FIG. 1)

However, in the conventional light emitting device as described above, the drive circuit is once provided with an insulated constant voltage drive circuit, and the light emitting diodes having different emission colors are provided on the secondary side of the insulated constant voltage drive circuit. A drive circuit is required. The drive circuit can be an inexpensive resistor or a circuit utilizing the control characteristics of the active region of the semiconductor. However, since the efficiency of the drive circuit is reduced, a relatively efficient switch mode is generally used. A control circuit such as a DC / DC converter is used. However, since a constant current driving DC / DC converter is required for each light emitting diode having a different emission color, the cost is high.
Lighting fixtures using light emitting diodes often require light of a light bulb color (light source color), that is, light having a color temperature slightly lower than pure white. In such a case, a plurality of pure white light emitting diodes are mainly used. In many cases, a desired color temperature is obtained by combining light emission outputs which are subordinates of small outputs by a small number of red light emitting diodes and green light emitting diodes, in addition to obtaining light emission outputs.

However, even in such a case, the conventional method has the following problems.
・ Constant circuit drive DC / DC converter connected to the secondary side of the insulation type constant voltage drive circuit requires two or more circuits for the main light emission output and the light emission output subordinate to the small output, and the circuit is complicated. Become.
Therefore, the number of parts increases, reliability decreases, and cost increases.
-The constant current drive DC / DC converter for light emission output, which is a subordinate of the small output, requires a low power one, so it is difficult to obtain a high efficiency one, and the electrical efficiency of the light emitting diode drive circuit is reduced. Was invited.

・ On the other hand, it is conceivable to use a plurality of non-insulated constant current driving DC / DC converters without using an insulating constant voltage driving circuit. However, the circuit becomes complicated and, for safety reasons, a light emitting diode. It is necessary to insulate it, resulting in high costs.
In addition, in the case where the number of light emitting diodes for obtaining a light output corresponding to a small output is small, such as 1 to 2, the driving voltage is low, and the difference from the driving voltage with a large number of series light emitting diodes that obtain the main light emitting output. Therefore, the voltage step-down ratio of the DC / DC converter that drives the light-emitting diode for obtaining the light-emitting output that is the subordinate of the small output increases, and the efficiency further decreases.

The present invention has been made to solve the above-described problems, and an object thereof is to obtain the following light emitting device and lighting device.
A plurality of light emitting elements having different driving currents can be driven with a simple driving circuit.
・ Low cost.
・ High reliability.
・ Small size.
・ Electric efficiency is high.

In the light emitting device according to the present invention,
A light-emitting device having a light-emitting element series circuit and a drive circuit,
The light emitting element series circuit has first and second light emitting element units connected in series, and the first light emitting element unit has one or a plurality of first light emitting elements connected in series. The second light emitting element unit has one or a plurality of second light emitting elements connected in series with a driving current larger than that of the first light emitting element.
The drive circuit has a transformer, current detection means, voltage detection means, current limiting means, and a control circuit.
The transformer has a primary winding, a first output winding that outputs a first drive voltage, and a second output winding that outputs a second drive voltage;
The light emitting element series circuit is connected to the first output winding of the transformer, and the first light emitting element unit is driven by the first drive current supplied from the first output winding.
The second light emitting element unit is connected to the second output winding of the transformer, supplied with an additional current from the second output winding, and a second driving current is added to the first driving current. Driven by drive current,
The current detection means detects the first or second drive current,
The voltage detection means detects the first or second drive voltage,
The current limiting means is connected to the second output winding of the transformer and limits a current for addition to the second light emitting element unit.
The control circuit controls the first or second drive current and the first or second drive voltage based on the first or second drive current and the first or second drive voltage.

  And the illuminating device in this invention is equipped with the light-emitting device as described in the previous paragraph.

In the light emitting device according to the present invention,
A light-emitting device having a light-emitting element series circuit and a drive circuit,
The light emitting element series circuit has first and second light emitting element units connected in series, and the first light emitting element unit has one or a plurality of first light emitting elements connected in series. The second light emitting element unit has one or a plurality of second light emitting elements connected in series with a driving current larger than that of the first light emitting element.
The drive circuit has a transformer, current detection means, voltage detection means, current limiting means, and a control circuit.
The transformer has a primary winding, a first output winding that outputs a first drive voltage, and a second output winding that outputs a second drive voltage;
The light emitting element series circuit is connected to the first output winding of the transformer, and the first light emitting element unit is driven by the first drive current supplied from the first output winding.
The second light emitting element unit is connected to the second output winding of the transformer, supplied with an additional current from the second output winding, and a second driving current is added to the first driving current. Driven by drive current,
The current detection means detects the first or second drive current,
The voltage detection means detects the first or second drive voltage,
The current limiting means is connected to the second output winding of the transformer and limits a current for addition to the second light emitting element unit.
The control circuit controls the first or second drive current and the first or second drive voltage based on the first or second drive current and the first or second drive voltage. ,
A light emitting device that can drive a plurality of light emitting elements having different driving currents with a simple driving circuit and has high electric efficiency can be obtained. In addition, since the load of the drive circuit can be controlled by controlling the first or second drive current and the first or second drive voltage, for example, when the first or second light emitting element has an open circuit failure. In addition, the drive circuit can be prevented from being overloaded.

  And since the illuminating device in this invention is equipped with the light emitting device as described above, a plurality of light emitting elements having different driving currents can be driven by a simple driving circuit and an illuminating device having high electric efficiency is obtained. be able to. In addition, since the load of the drive circuit can be controlled by controlling the first or second drive current and the first or second drive voltage, for example, when the first or second light emitting element has an open circuit failure. In addition, the drive circuit can be prevented from being overloaded.

Embodiment 1 FIG.
1 and 2 show a first embodiment for carrying out the present invention. FIG. 1 is a circuit diagram showing a configuration of a light emitting device, and FIG. 2 is a waveform diagram of each part. In FIG. 1, this light-emitting device is used for a lighting fixture to obtain a light bulb color. Further, the configuration of the power supply in this drive circuit is generally called a flyback converter, and is known as an insulating switching power supply that performs an ON / OFF operation. In FIG. 1, the light emitting device includes a drive circuit 100 and a light emitting element series circuit 20. The drive circuit 100 is configured as follows. The drive circuit 100 includes an input capacitor 1 that inputs power, a transformer 2 that insulates power on the primary side and transmits it to the secondary side, and an open / close that switches the input voltage and stores necessary energy in the transformer 2. It has a MOSFET 3 as means and a control circuit 4 that controls the opening and closing of the MOSFET 3 based on a signal from the photocoupler 12.

  The transformer 2 insulates the primary side from the secondary side, the primary winding 2a, the main secondary winding 2b as the first output winding, and the secondary secondary as the second output winding. A winding 2c is provided. Further, a main secondary rectifier diode 5 that rectifies the output of the main secondary winding 2b of the transformer 2, and a main secondary smoothing capacitor 6 that smoothes the output of the main secondary winding 2b rectified by the main secondary rectifier diode 5. And have.

  Furthermore, it has a secondary secondary rectifier diode 13a that rectifies the output of the secondary secondary winding 2c, and a secondary secondary smoothing capacitor 14a that smoothes the output of the secondary secondary winding 2c rectified by the secondary secondary rectifier diode 13a. . A light emitting element series circuit 20 described later is connected to the main secondary winding 2b of the transformer 2 via a current detection resistor 9 as current detection means. Further, a slave light emitting diode 8a (detailed later) is connected to the slave secondary winding 2c of the transformer 2 via a slave current limiting resistor 15 as current limiting means. The secondary current limiting resistor 15 limits the current flowing into the secondary light emitting diode 8a.

  Furthermore, an error amplifier 10 that performs an operation based on the voltage generated in the current detection resistor 9 and the reference voltage of the reference voltage source 11 and outputs an output signal to the photocoupler 12, and outputs the error amplifier 10 to the photocoupler 12. The voltage detection resistor 22 and the voltage detection resistor 23, and the voltage detection resistor 22 and the voltage detection resistor 23 are connected to the output of the main secondary winding, and the voltage detection resistor 22 and the voltage detection resistor 23 divide the voltage. Error amplifier 24 that performs an operation based on the measured voltage and the reference voltage of the reference voltage source 11, a diode 26 that transmits an output signal of the error amplifier 24 to the photocoupler 12, and output signals from the error amplifier 10 and the error amplifier 24 And a photocoupler 12 that sends the signal to the control circuit 4. The drive circuit 100 is configured as described above.

In the light emitting element series circuit 20, a main light emitting diode 7 serving as a main light emitting output as a first light emitting element unit and a sub light emitting diode 8a serving as a sub light output as a second light emitting element unit are connected in series. Configured.
Here, the main light emitting diode 7 is configured by connecting four white light emitting diodes 7a to 7d in series, and the sub light emitting diode 8a uses one red light emitting diode which may have a small light emission output. That is, four white light emitting diodes and one red light emitting diode are used. The white light emitting diodes 7a to 7d are supplied with 350 mA as the first driving current (main current J1), and the red light emitting diode is supplied with 400 mA as the second driving current (secondary driving current SJ1). , Creating a light bulb color. The sub drive current SJ1 for driving the sub light emitting diode 8a is 50 mA larger than the main current J1 for driving the main light emitting diode 7 as the first drive current.

Next, the operation of energy transmission between the primary and secondary windings of the transformer 2 in the drive circuit 100 will be described.
FIG. 2 shows the operation waveform of each part. The relationship between the ON / OFF operation of the MOSFET 3 and the primary side current CU1, the secondary side current CU2 of the transformer 2 and the secondary side output voltage Vo is plotted on the horizontal axis. Show. A DC power supply is connected to the input portions at both ends of the input capacitor 1 to supply DC power.
At time t1, when the MOSFET 3 is turned on by a signal from the control circuit 4, the current of CU1 flows through the primary winding 2a of the transformer 2, and the energy of this current is accumulated in the transformer 2 as magnetic energy.

At time t2, when MOSFET 3 is turned off by a signal from control circuit 4, the energy stored in transformer 2 is transmitted to main secondary winding 2b magnetically coupled inside transformer 2, and is subjected to main secondary rectification as current CU2. The current flows to the main secondary smoothing capacitor 6 through the diode 5, and is charged to the main secondary smoothing capacitor 6 as the DC voltage VDC1.
Similarly, energy is transmitted to the secondary winding 2c, current flows also to the secondary secondary rectifier diode 13a and the secondary secondary smoothing capacitor 14a, and the secondary secondary smoothing capacitor 14a is charged as the DC voltage VDC2. Is done.

After time t3, repeated operations from time t1 to time t2 are performed.
In other words, when the primary current flows ON, the secondary current does not flow OFF, and when the primary current does not flow, the secondary current flows ON. This operation is generally referred to as ON / OFF operation. Thus, the switching power supply that performs the ON / OFF operation is called a flyback converter, and energy, that is, electric power is transmitted from the primary side to the secondary side through the transformer 2.

Next, constant current feedback control of the drive circuit of FIG. 1 will be described.
A main light emitting diode 7 and a sub light emitting diode 8a are connected in series as a light emitting element series circuit 20 to the DC voltage output from the main secondary winding 2b. A main current J1 (350 mA) is passed through the white light emitting diodes 7a to 7d, which are the main light emitting diodes 7, in order to obtain a necessary light output. The slave light emitting diode 8a needs 400 mA to output the necessary light emission output, so that only the current 350 mA of the main current J1 is insufficient. The deficient current is supplied from the DC voltage output from the secondary winding 2c, which is another winding of the transformer 2, to the secondary light emitting diode 8a through the secondary current limiting resistor 15. To do. The sub light emitting diode 8a is driven by a sub drive current SJ1 as a second drive current obtained by adding the current L1 according to the main current J1.

  Here, the slave current limit is based on the output voltage of the slave secondary winding 2c and the forward voltage of the slave light emitting diode 8a so that the slave drive current SJ1 is 400 mA, that is, the slave current L1 is 400−350 = 50 mA. The resistor 15 is set. The secondary current L1, which is a shortage current of the secondary light emitting diode 8a supplied from the output of the secondary secondary winding 2c, is the secondary secondary winding 2c → secondary rectifier diode 13a → (secondary secondary smoothing capacitor 14a) → The current flows through a loop of the secondary current limiting resistor 15 → the secondary light emitting diode 8a → the secondary secondary winding 2c. Therefore, the sub current L1 flows only in the sub light emitting diode 8a and does not flow in the main light emitting diode 7 and the current detection resistor 9.

  The main current J1 is the main secondary winding 2b → the main secondary rectifier diode 5 → the (main secondary smoothing capacitor 6) → the main light emitting diode 7 → the sub light emitting diode 8a → the current detection resistor 9 → the main secondary winding. It flows in a loop of 2b. Note that the power consumed by the error amplifier 10 and the error amplifier 24, that is, the flowing current is sufficiently small, and can be ignored if the main current J1 is sufficiently larger than this current. Therefore, in the case of the first embodiment, the main current J2 flowing through the current detection resistor 9 can be regarded as the same value as the main current J1. The main current J2 flows through the current detection resistor 9 to generate a detection voltage Vd at both ends of the current detection resistor 9, and the voltage is input to the error amplifier 10. The resistance value of the current detection resistor 9 is a predetermined main current J2, in this embodiment, when 350 mA flows, an output voltage is obtained from the error amplifier 10 by calculating the detection voltage Vd and the reference voltage of the reference voltage source 11. Select as follows.

Next, the constant voltage feedback control of FIG. 1 will be described.
A series circuit of a voltage detection resistor 22 and a voltage detection resistor 23 as voltage detection means and voltage division means is connected to the main secondary winding 2b. Since the main current J11 flows through the voltage detection resistor 22 and the voltage detection resistor 23, the output voltage of the main secondary winding 2b is divided, and the detection voltage Vdd is generated at both ends of the voltage detection resistor 23. However, in order to reduce electrical loss, the resistance values of the voltage detection resistor 22 and the voltage detection resistor 23 are set to sufficiently large values so that the magnitude of the main current J11 does not become a problem compared to the magnitude of the main current J1. To do.
When the output voltage of the main secondary winding 2b rises and reaches a predetermined voltage, the detection voltage Vdd that is the divided voltage also rises and reaches a predetermined voltage. The error amplifier 24 calculates the reference voltage of the reference voltage source 11 and the detection voltage Vdd. When the detection voltage Vdd increases, the output signal of the error amplifier 24 increases.

Output signals from both the error amplifier 10 and the error amplifier 24 are output to the primary side of the photocoupler 12 via the diode 25 and the diode 26. At this time, the output signals of the respective error amplifiers 10 and 24 are restricted so that only the forward direction is conducted by the diode 25 and the diode 26 and the reverse direction is cut off, so that the output signals of the respective error amplifiers are affected. The signal is input to the primary side of the photocoupler 12 without giving.
With such a configuration, it is more effective that the output signals of the error amplifier 10 and the error amplifier 24 increase first in the switching period.
When the main current J1 flows through the series light emitting element circuit 20 and the predetermined main current J2 flows through the current detection resistor 9, the detection voltage Vd and the reference voltage of the reference voltage source 11 are calculated, and the output signal of the error amplifier 10 is output. Increases, the current for driving the primary side of the photocoupler 12 increases.
Similarly, when the main current J11 flows through the voltage detection resistor 22 and the voltage detection resistor 23, which are voltage detection means, the calculation of the detection voltage Vdd generated at the voltage detection resistor 23 and the reference voltage of the reference voltage source 11 is performed. The output signal of the amplifier 24 increases, increasing the current driving the primary side of the photocoupler 12.

In this way, the current on the primary side of the photocoupler 12 can be increased by increasing the output signal of one or both of the error amplifier 10 and the error amplifier 24. Accordingly, the secondary of the photocoupler 12 is increased. The side current also increases.
When the output current on the secondary side of the photocoupler 12 increases, the control circuit 4 is configured to reduce the ratio of the ON time in the ON / OFF time of the MOSFET 3, that is, to reduce the duty ratio. By inputting the current signal transmitted to the secondary side of the coupler to the control circuit 4, the duty ratio of the ON / OFF operation of the MOSFET 3 can be controlled.
That is, when the output current on the secondary side of the photocoupler 12 increases, the duty ratio of the MOSFET 3 decreases, the energy transmitted to the primary winding 2a of the transformer 2 decreases, and the main and secondary secondary windings 2b, 2c. Output voltage is limited, and the current flowing through the main and secondary light emitting diodes 7 and 8a and the voltage applied to the light emitting element series circuit 20 are limited.

  Using such a signal transmission path, current feedback control is performed using the main current J2 flowing through the current detection resistor 9 (in this embodiment, main current J2≈main current J1), and the voltage detection resistor 23 is used. Constant voltage feedback control of the output voltage of the main secondary winding 2b is performed. Accordingly, the drive circuit 100 includes a transformer 2 having a primary winding 2a and a main secondary winding 2b, a MOSFET 3, a control circuit 4, a current detection resistor 9, an error amplifier 10, a voltage detection resistor 22, a voltage detection resistor 23, One constant current drive circuit having a voltage limiting function constituted by the error amplifier 24 is provided.

  Conventionally, when driving light emitting diodes having different required currents, a DC / DC converter for constant current drive has been individually provided on the secondary side of the insulated constant voltage drive circuit. According to the embodiment, an insulating constant voltage drive circuit and a constant current drive DC / DC converter are not required, and a plurality of types of light emitting diodes having different drive voltages can be formed by one constant current drive circuit having a voltage limiting function. It becomes possible to obtain the light emission output required for each driving.

  Regardless of this embodiment, a main light emitting diode and a sub light emitting diode are connected in parallel from the output voltage of one DC / DC converter for constant current driving as in the prior art, and each is connected via a current limiting resistor. When configured to flow a constant current, the same output voltage (forward voltage on the main light emitting diode side x set according to the number of connections) is also applied to the sub light emitting diode side, so the current limiting resistance on the sub light emitting diode side is increased. Power loss is increased and electrical efficiency is reduced. In other words, in the conventional method, the main light emitting diode is driven at a constant current by the DC / DC converter for constant current drive on the secondary side of the insulated constant voltage drive circuit, and the output voltage of the same DC / DC converter is used. If the secondary light emitting diode is also driven (that is, when the primary light emitting diode and the secondary light emitting diode are connected in parallel), the voltage value between the secondary light emitting diode side is large and the current value must be greatly limited. I must. If the current value is largely limited, the electric efficiency is greatly reduced.

  In the present embodiment, the condition is that the slave drive current SJ1 necessary for the slave light emitting diode 8a to obtain a desired light emission output is larger than the master current J1 required for the master light emitting diode 7. The number of turns of the main secondary winding 2b is set so that an output voltage corresponding to or larger than the forward voltage of the main light emitting diode 7 × the number of connections can be output. The number of turns of the secondary winding 2c is set so that an output voltage corresponding to or larger than the forward voltage of the secondary light emitting diode 8a × the number of connections can be output.

The output voltage of the main secondary winding controlled by the voltage detection resistor 22 and the voltage detection resistor 23, that is, the predetermined voltage is the forward direction of the diode when a predetermined current is passed through the diode constituting the light emitting element series circuit 20. The voltage is set to be slightly larger than a voltage value obtained by adding the total voltage and the detection voltage Vd generated in the current detection resistor 9.
Further, the resistance values of the voltage detection resistor 22 and the voltage detection resistor 23 are set to sufficiently large values so that the main current J11 can be ignored as compared with the main current J1.

Of course, the light emission colors of the main light emitting diode 7 and the sub light emitting diode 8a may be colors other than white and red. Further, the number of main light emitting diodes 7 and sub light emitting diodes 8a may be changed. The order of serial connection of the main light emitting diode 7 and the sub light emitting diode 8a may be changed.
When a plurality of main light emitting diodes 7 are used, they may be of different types as long as the driving current (main current) is the same. When a plurality of sub light emitting diodes 8a are used, they may be of different types as long as the driving current (main current + sub current) is the same.

Further, although the secondary current limiting resistor 15 is used as the current limiting means, the current limiting can be performed using other current limiting means such as a constant current circuit. Similarly, the current detection resistor 9 is used as the current detection means, but current detection can also be performed using other current detection means. The error amplifier 10 is configured to output the output voltage by calculating the detection voltage Vd and the reference voltage of the reference voltage source 11, but the error amplifier may be configured by another configuration such as an integrator.
Similarly, the error amplifier 24 is configured so that the output voltage is output by the calculation of the detection voltage Vdd and the reference voltage of the reference voltage source 11, but the error amplifier is configured by another configuration, for example, an integrator or the like. Alternatively, other means that can perform constant voltage control may be used.

In this embodiment, an example in which two error amplifiers are used has been described, but other configurations, for example, an IC such as an analog multiplier, a microcomputer, or the like may be used.
In this embodiment, a flyback converter is used as the drive circuit. However, any drive circuit that can control the output, such as a forward converter, can be used.
Further, in the above description, the main current J2 that is the first driving current is controlled. However, instead of controlling the main current J2, the sub driving current as the second driving current for driving the sub light emitting diode 8a is used. The slave drive current SJ1 may be controlled by detecting SJ1.

As described above, according to this embodiment, the following operational effects can be obtained.
A plurality of light emitting diodes having different driving currents can be driven with a simple driving circuit.
-Since the number of parts can be reduced, parts costs can be reduced.
-Since the number of parts can be reduced, the mounting cost of parts can be reduced.
-Since the number of parts can be reduced, the circuit scale can be reduced.
Even when the type and quantity of the sub light emitting diodes to be driven are increased, it is possible to suppress an increase in the cost of the driving circuit.

・ By simplifying the circuit configuration, the number of parts can be reduced, improving reliability.
In the conventional light emitting device, the drive circuit is once provided with an insulation type constant voltage drive circuit, and a constant current drive DC / DC converter is provided for each light emitting diode having a different emission color on the secondary side of the constant voltage drive circuit. However, in this embodiment, a single constant current drive circuit can be used.
-For this reason, power loss can be reduced and electrical efficiency can be improved.
In the present embodiment, even in one constant current driving circuit, the secondary light emitting diode 8a is required by the secondary secondary winding 2c (secondary output winding) provided separately from the main secondary winding 2b. By supplying the subordinate current L1 that is the amount obtained by subtracting the main current J1 from the current, the loss at the subcurrent limiting resistor 15 can be reduced. Therefore, the power loss can be further reduced and the electric efficiency can be improved. .

Especially when a plurality of constant current drive DC / DC converters are used on the secondary side of an insulated constant voltage drive circuit as in the prior art, a small capacity for light output, which is a subordinate of a small output, is high. Although it is difficult to configure an efficient constant current driving DC / DC converter, the present embodiment simplifies the configuration of the driving circuit, improves the electrical efficiency, and contributes to energy saving.
-By adopting constant current control combined with voltage limiting function by voltage detection means, even if the forward voltage is large at the start of driving of the light emitting element, the output voltage rise of the main secondary winding can be suppressed at a constant voltage value, After that, when the forward voltage decreases, constant current driving that is constant current driven at a desired current value becomes possible.

・ Also, with the constant current control method combined with the voltage limiting function as described above, even when the forward voltage of the light emitting element immediately after lighting is large, the drive circuit becomes excessive due to excessive power trying to flow a predetermined drive current. It is possible to prevent a load and improve the reliability of the drive circuit.
-The constant current control combined with the voltage limiting function can prevent overvoltage even when the light emitting diode fails in the open mode.
In addition, since overvoltage can be prevented, a high-voltage product is not required for the rectifier diode or capacitor on the secondary side, and the drive circuit can be configured at low cost.
-The constant current control combined with the voltage limiting function can prevent overcurrent even if the light emitting diode fails in the short-circuit mode.

As in this embodiment, when the number of main light emitting diodes 7 (7a to 7d) is large and the number of sub light emitting diodes 8a is small, further improvement in electric efficiency can be expected as compared with the conventional case.
In a conventional drive circuit for a light emitting device, an insulation type constant voltage drive circuit is temporarily provided, and a constant current drive DC / DC converter is provided for each light emitting diode having a different emission color on the secondary side of the constant voltage drive circuit. However, in this embodiment, since it can be configured by one drive circuit, the number of constant current drive DC / DC converters that perform a switching operation is reduced, thereby reducing electromagnetic noise.

Embodiment 2. FIG.
FIG. 3 shows a circuit diagram of the light emitting device according to the second embodiment.
In FIG. 3, in the drive circuit 200, the main current J1 (main current J2) and the subcurrent L1 are made variable by using the current detection variable resistor 16 as the current detection means and the subcurrent limit variable resistance 17a as the current limit means. The luminance of the main light emitting diode 7 and the sub light emitting diode 8a can be changed. By changing the luminance of each of the main light emitting diode 7 and the sub light emitting diode 8a, the color temperature according to the combination of the light emission outputs of the main light emitting diode 7 and the sub light emitting diode 8a can also be changed.

  Of course, only one of the current detection variable resistor 16 and the sub-current limiting variable resistor 17a may be configured with a variable resistor. Further, in the current detecting means and the current limiting means, means other than the variable resistor, such as a digital potentiometer or a transistor, may be used.

Embodiment 3 FIG.
FIG. 4 shows a circuit diagram of the light emitting device according to the third embodiment.
In FIG. 4, the drive circuit 300 uses the sub current limiting circuit 18 as a current limiting means.
The shortage current is supplied to the sub light emitting diode 8a as the sub current L1. The sub current limiting circuit 18 uses a constant current circuit, a three-terminal regulator, or the like, and is configured not to flow a current exceeding a predetermined upper limit value, that is, a current required for the sub light emitting diode 8a.

  With this configuration, even when the slave light emitting diode 8a fails in the short-circuit mode, the current is limited so as not to exceed the predetermined upper limit value. Therefore, the power loss of the current loop of the slave light emitting diode 8a is reduced. The increase can be suppressed, and it becomes possible to continue driving only the main light emitting diode 7. Although the main light emitting diode 7 alone cannot emit light at a desired color temperature, it is possible to prevent the light from being turned off as a minimum function as a lighting fixture, and to suppress a decrease in reliability.

Embodiment 4 FIG.
FIG. 5 shows a circuit diagram of a light emitting device according to the fourth embodiment.
In FIG. 5, in the drive circuit 400, the sub light emitting diode 8 b is inserted between the sub light emitting diode 8 a and the current detection variable resistor 16. The main light emitting diode 7, the sub light emitting diode 8 a, and the sub light emitting diode 8 b are connected in series and constitute a light emitting element series circuit 30. A current that is insufficient for the secondary light emitting diode 8a is supplied as the secondary current L1 from the secondary secondary winding 2c via the secondary current limiting variable resistor 17a, and is insufficient for the secondary light emitting diode 8b via the secondary current limiting variable resistor 17b. The current is supplied as a sub current L2 as another additional current.

  The secondary current L1 is the secondary secondary winding 2c → secondary rectifier diode 13a → (secondary smoothing capacitor 14a) → secondary current limiting variable resistor 17a → secondary light emitting diode 8a → secondary light emitting diode 8b → secondary winding. It flows in a loop of 2c. A sub current L1 as an additional current is supplied to the sub light emitting diode 8a and the sub light emitting diode 8b, and the sub light emitting diode 8a is driven by a sub driving current SJ1 as a second driving current obtained by adding the current L1 according to the main current J1. Is done. The value of the secondary current L1 is set by the output voltage of the secondary secondary winding 2c, the forward voltage of the secondary light emitting diode 8a, the forward voltage of the secondary light emitting diode 8b, and the secondary current limiting variable resistor 17a.

  The secondary current L2 flows in a loop of the secondary secondary winding 2c → secondary rectifier diode 13a → (secondary smoothing capacitor 14a) → secondary current limiting variable resistor 17b → secondary light emitting diode 8b → secondary winding 2c. . A slave current L2 as an additional current is supplied to the slave light emitting diode 8b, and the slave light emitting diode 8b is driven by a slave drive current SJ2 as a second drive current obtained by adding the slave current L1 and the slave current L2 to the master current J1. Will be. The current value of the secondary current L2 is set by the output voltage of the secondary secondary winding 2c, the forward voltage of the secondary light emitting diode 8b, and the secondary current limiting variable resistor 17b. However, it is necessary to set the sub current L2 in consideration of the fact that the main current J1 and the sub current L1 already flow in the sub light emitting diode 8b.

With such a configuration, a plurality of light emitting diodes having different driving currents can be driven with a simple driving circuit. Moreover, even when the type and quantity of the sub light emitting diodes to be driven are increased, an increase in the cost of the driving circuit can be suppressed. Of course, the sub light emitting diode 8a and the sub light emitting diode 8b may be the same type or different types. Two or more slave light emitting diodes constituting the slave light emitting element unit may be used. If the sub light emitting diode 8a and the sub light emitting diode 8b are of the same type and have the same desired light output, it is necessary to supply the sub current L2 through the loop of the sub current limiting variable resistor 17b as shown in FIG. Not
The sub current L1 may be supplied to the sub light emitting diode 8a and the sub light emitting diode 8b connected in series.

  Also, by combining two or more types of light emitting outputs of different types of sub light emitting diodes with the light emitting output of the main light emitting diodes, compared to the case of combining the light emitting output of the main light emitting diodes and the light emitting output of one type of sub light emitting diodes The range of color temperature that can be created is widened, and it becomes possible to create many shades.

Embodiment 5 FIG.
FIG. 6 shows a circuit diagram of a light emitting device according to the fifth embodiment.
In FIG. 6, the transformer 210 in the drive circuit 500 is obtained by adding a secondary secondary winding 2d. Further, the main light emitting diode 7, the sub light emitting diode 8a, and the sub light emitting diode 8b are connected in series to form a light emitting element series circuit 30. The output voltage obtained from the secondary secondary winding 2d via the secondary secondary rectifier diode 13b and the secondary secondary smoothing capacitor 14b is insufficient with respect to the secondary light emitting diode 8b via the secondary current limiting variable resistor 17b. A current (secondary current L12) is supplied.

  The secondary current L12 flows through a loop of the secondary secondary winding 2d → secondary rectifier diode 13b → (secondary smoothing capacitor 14b) → secondary current limiting variable resistor 17c → secondary light emitting diode 8b → secondary winding 2d. . The current value of the secondary current L12 is set by the output voltage of the secondary secondary winding 2d, the forward voltage of the secondary light emitting diode 8b, and the secondary current limiting variable resistor 17c.

  The sub current L1 flows only in the sub light emitting diode 8a and does not flow in the sub light emitting diode 8b. Further, the secondary current L12 does not flow through the secondary light emitting diode 8a. The sub light emitting diode 8a is driven by a sub driving current SJ1 as a second driving current obtained by adding the main current J1 and the sub current L1 as an additional current, and the sub light emitting diode 8b is connected to the main current J1. Driving is performed by the slave drive current SJ3 as the second drive current, which is added with the slave current L12 as the additional current.

The secondary current L1 is the same as that shown in FIG. 1 of the first embodiment, and the secondary secondary winding 2c → secondary rectifier diode 13a → (secondary smoothing capacitor 14a) → secondary current limiting variable resistance. It flows in a loop of 17a → secondary light emitting diode 8a → secondary winding 2c.
The current value of the secondary current L1 is set by the output voltage of the secondary secondary winding 2c, the forward voltage of the secondary light emitting diode 8a, and the secondary current limiting variable resistor 17a.

  With such a configuration, a plurality of light emitting diodes having different driving currents can be driven with a simple driving circuit. Moreover, even when the type and quantity of the sub light emitting diodes to be driven are increased, an increase in the cost of the driving circuit can be suppressed. Of course, the sub light emitting diode 8a and the sub light emitting diode 8b may be the same type or different types. Two or more slave light emitting diodes constituting the slave light emitting element unit may be used.

  Similarly to the fourth embodiment, the light emission output of the main light emitting diode and the light emission output of one type of sub light emitting diode are combined by combining two or more types of light emission outputs of the different types of sub light emitting diodes with the light emission output of the main light emitting diode. Compared with the combination of, the range of color temperatures that can be created is widened, and it is possible to create many shades.

Embodiment 6 FIG.
FIG. 7 shows a circuit diagram of a light emitting device according to the sixth embodiment.
In FIG. 7, a transformer 211 in the drive circuit 600 is provided with a secondary winding 2e. The secondary winding 2e is provided with an intermediate tap, and the secondary winding 2e is configured by connecting the first winding 2e1 and the second winding 2e2 in common with one of the terminals. Further, the main light emitting diode 7, the sub light emitting diode 8a, and the sub light emitting diode 8b are connected in series to form a light emitting element series circuit 30. Since a positive and negative voltage is output to the secondary winding 2e centering on the potential of the intermediate tap, a positive DC voltage is obtained using the secondary secondary rectifier diode 13a and the secondary secondary smoothing capacitor 14a. A negative DC voltage is obtained using the secondary rectifier diode 13c and the secondary secondary smoothing capacitor 14c.

Subordinate current L1 and subcurrent L22 are supplied to each of the sub light emitting diodes as a deficient current via the current limiting variable resistor 17a and the current limiting variable resistor 17c. The secondary current L1 is intermediate between the winding 2e1 (positive voltage) → secondary rectifier diode 13a → (secondary smoothing capacitor 14a) → secondary current limiting variable resistor 17a → secondary light emitting diode 8a → secondary winding 2e. It flows in a tap loop. The sub light emitting diode 8a is driven by the sub drive current SJ1 as the second drive current obtained by adding the main current J1 and the sub current L1 as the additional current.
The current value of the secondary current L1 is set by the output voltage of the winding 2e1 (positive voltage), the forward voltage of the secondary light emitting diode 8a, and the secondary current limiting variable resistor 17a.

The secondary current L22 is an intermediate tap of the secondary secondary winding 2e → secondary light emitting diode 8b → (secondary smoothing capacitor 14c) → secondary current limiting variable resistor 17c → secondary rectifier diode 13c → winding 2e2 (negative voltage) ) In the loop. The sub light emitting diode 8b is driven by the sub drive current SJ4 as the second drive current obtained by adding the main current J1 and the sub current L22 as the additional current.
The current value of the secondary current L22 is set by the output voltage (negative voltage) of the winding 2e2, the forward voltage of the secondary light emitting diode 8b, and the secondary current limiting variable resistor 17c. With such a configuration, a plurality of slave light emitting element units can be driven, and the types and quantities of the driven slave light emitting diodes can be increased.

Of course, the sub light emitting diode 8a and the sub light emitting diode 8b may be the same type or different types. Two or more slave light emitting diodes constituting the slave light emitting element unit may be used.
Similarly to the fourth and fifth embodiments, the light emission output of the main light emitting diode and the light emission output of one type of sub light emitting diode are combined by combining two or more types of light emission outputs of the different types of sub light emitting diodes with the light emission output of the main light emitting diode. Compared to the case of combining light output, the range of color temperatures that can be created is widened, and it is possible to create many shades.
Further, in the seventh embodiment, since the transformer 211 uses an intermediate tap for the secondary winding 2e, the wiring to the sub light emitting diode can be reduced by one compared to the fifth embodiment. Can do. As a result, the circuit can be made inexpensive and small.

  Although the one using the main secondary rectifier diode 5 and the secondary secondary rectifier diodes 13a, 13b, and 13c has been shown as the one-way conduction device, other one-way conduction devices such as a synchronous rectification type rectifier using a MOSFET or the like are used. May be used.

  When the lighting device is configured using the light-emitting device as described in each of the above embodiments, a lighting device that exhibits the same effect as the light-emitting device described in each of the above-described embodiments can be obtained.

It is a circuit diagram which shows the structure of the light-emitting device which is Embodiment 1 of this invention. It is a wave form diagram which shows the operation | movement waveform which is Embodiment 1 of this invention. It is a circuit diagram which shows the structure of the light-emitting device which is Embodiment 2 of this invention. It is a circuit diagram which shows the structure of the light-emitting device which is Embodiment 3 of this invention. It is a circuit diagram which shows the structure of the light-emitting device which is Embodiment 4 of this invention. It is a circuit diagram which shows the structure of the light-emitting device which is Embodiment 5 of this invention. It is a circuit diagram which shows the structure of the light-emitting device which is Embodiment 6 of this invention.

Explanation of symbols

2,210,211 transformer, 2a primary winding, 2b main secondary winding,
2c-2e secondary winding, 3 MOSFET, 4 control circuit,
5 main secondary rectifier diodes, 7 main light emitting diodes, 7a to 7d main light emitting diodes,
8a, 8b secondary light emitting diode, 9 current detection resistor, 10 error amplifier,
11 Reference voltage source, 13a-13c Secondary secondary rectifier diode, 15 Subcurrent limiting resistor,
16 Current detection variable resistor, 17a-17c Subcurrent limiting variable resistor,
18 Subcurrent limiting circuit, 20, 30 Light emitting element series circuit, 22, 23 Voltage detection resistor,
24 Error amplifier, 100, 200, 300, 400, 500, 600 Drive circuit.

Claims (6)

A light-emitting device having a light-emitting element series circuit and a drive circuit,
The light emitting element series circuit includes first and second light emitting element units connected in series, and the first light emitting element unit is one or a plurality of first light emitting elements connected in series. And the second light emitting element unit has one or a plurality of second light emitting elements connected in series, each having a driving current larger than that of the first light emitting element,
The drive circuit includes a transformer, current detection means, voltage detection means, current limiting means, and a control circuit.
The transformer includes a primary winding, a first output winding that outputs a first drive voltage, and a second output winding that outputs a second drive voltage;
The light emitting element series circuit is connected to the first output winding of the transformer, and the first light emitting element unit is driven by a first drive current supplied from the first output winding,
The second light emitting element unit is connected to the second output winding of the transformer and supplied with an additional current from the second output winding, and the additional current is added to the first driving current. Driven by the generated second drive current,
The current detection means detects the first or second drive current,
The voltage detection means detects the first or second drive voltage,
The current limiting means is connected to the second output winding of the transformer and limits the current for addition to the second light emitting element unit.
The control circuit controls the first or second drive current and the first or second drive voltage based on the first or second drive current and the first or second drive voltage. A light-emitting device. 2. The control circuit according to claim 1, wherein the control circuit controls the first or second drive current to a constant value within a range in which the first or second drive voltage does not exceed a predetermined value. Light-emitting device. The light emitting device according to claim 1, wherein the current detection unit and the current limiting unit are variable resistors. 2. The plurality of second light emitting element units are connected in series, and a plurality of the current limiting means are provided corresponding to each of the second light emitting element units. The light emitting device according to any one of claims 3 to 4. A plurality of the second light emitting element units are connected in series, and a plurality of the second output windings and the current limiting means of the transformer are provided corresponding to the second light emitting element units. 4. Each of the second light emitting element units is connected to each of the second output windings via the current limiting means, respectively. The light emitting device according to claim 1. An illuminating device comprising the light emitting device according to any one of claims 1 to 5.

Images