JP6094959B2 - Lighting device and lighting apparatus - Google Patents

Description

  The present invention relates to a lighting device for lighting a solid light emitting element such as a light emitting diode (LED) and a lighting fixture using the same, and more particularly to a lighting device and a lighting fixture corresponding to different loads.

  Solid light emitting devices such as LEDs (Light Emitting Diodes) are expected to be new light sources for various lamps because of their high efficiency and long life.

  In LED lamps, LED lamps having various light outputs can be produced by changing the number of LEDs connected in series. However, when the number of LEDs connected in series changes, the forward voltage (Vf), which is the overall voltage drop that occurs when current flows through the plurality of LEDs, changes. Therefore, in order to make a lighting device corresponding to LED lamps having various light outputs, it is required that various forward voltages can be output to the LEDs.

  Therefore, various technologies have been proposed as lighting devices corresponding to different loads (that is, LED lamps having different forward voltages) (for example, Patent Document 1).

  Patent Document 1 proposes a lighting device in which the constant current characteristics are not impaired even when the load is different by devising the timing for turning on and off the switching elements constituting the chopper circuit. Thereby, the lighting device corresponding to different loads is realized.

JP 2011-210659 A

  However, in the conventional lighting device, the current flowing through the LED is kept constant, but the forward voltage applied to the entire LED increases as the load increases. For this reason, in the conventional lighting device, a large load of LED lamps is supplied with a large amount of power. Therefore, a large amount of heat is generated according to the supplied power, and the temperature of the components constituting the lighting device is high. There is a possibility of exceeding the allowable value.

  By the way, the lighting device is often used by being attached to a lighting fixture. In such a case, the thermal condition is further deteriorated. For example, when the lighting fixture that houses the lighting device has a sealed structure, the heat dissipation of the lighting device is deteriorated. In addition, when the lighting device is attached at a position close to the LED lamp, the lighting device is affected by the radiant heat from the LED lamp, and the temperature of the components constituting the lighting device further increases. Further, when the LED lamp is sealed in the lighting fixture together with the lighting device, the heat dissipation of the lighting device is further deteriorated.

  As a result, in the conventional lighting device, the heat radiation is not performed well, the temperature of the components constituting the lighting device becomes higher than the allowable value, and the lighting device may be damaged in some cases. Conversely, the LED lamp is heated by the radiant heat from the lighting device or the LED lamp is not efficiently dissipated, so the temperature of the LED chip constituting the LED lamp rises and the LED chip is There is a possibility of deterioration.

  Therefore, depending on the form of the luminaire, it may occur that an LED lamp having a large forward voltage cannot be used, and such an LED lamp must be excluded from the object to which the luminaire is adapted. In that case, although it is a luminaire that can be adapted to different loads (different LED lamps), the function of the luminaire (the type of LED lamp that can be attached) is actually limited depending on the form of the luminaire. Can result.

  Therefore, the present invention has been made in view of the above circumstances, and is a lighting device corresponding to different loads, and even when a solid light-emitting element with a large load is turned on, heat generation is suppressed more than in the past. It aims at providing a lighting device and a lighting fixture.

In order to achieve the above object, a lighting device according to an embodiment of the present invention is a lighting device corresponding to different loads, and is a lighting device for supplying a current to a solid-state light emitting element connected to the lighting device as the load. A forward voltage detection circuit that detects a forward voltage that is a voltage drop of the solid state light emitting device when a current flows through the solid state light emitting device, and a forward voltage detected by the forward direction voltage detection circuit And a control circuit that controls the lighting circuit so that a smaller current flows through the solid state light emitting device as the current increases, and the control circuit is configured to supply current to the solid state light emitting device when the lighting device is turned on. Immediately after that, the lighting circuit is controlled so that it becomes a predetermined initial value and then increases to the target value with time, and when the current is the initial value, Determining the target value corresponding to the detected forward voltage at a forward voltage detection circuit.

  Here, the forward voltage detection circuit detects a first voltage as the forward voltage when the solid state light emitting element is a first solid state light emitting element, and the solid state light emitting element detects the first solid state element. In the case of the second solid state light emitting device having a load larger than that of the light emitting device, the forward voltage detects a second voltage larger than the first voltage, and the control circuit detects the forward voltage detecting circuit. When the forward voltage detected in step 1 is the first voltage, the lighting circuit is controlled so that the first current flows through the solid state light emitting device, and the forward direction detected by the forward voltage detection circuit. When the voltage is the second voltage, the lighting circuit may be controlled so that a second current smaller than the first current flows through the solid state light emitting device.

  As a specific control example, as the forward voltage detected by the forward voltage detection circuit increases, a smaller current flows through the solid-state light emitting element and the control circuit detects the forward voltage detection circuit. The lighting circuit may be controlled so that the product of the forward voltage detected by the forward voltage detection circuit and the current flowing through the solid state light emitting element is constant without depending on the forward voltage. . In the control circuit, the larger the forward voltage detected by the forward voltage detection circuit, the smaller the current flows through the solid-state light emitting element, and the forward voltage detected by the forward voltage detection circuit is You may control the said lighting circuit so that the light output of the said solid light emitting element becomes large, so that it is large.

  Here, the control circuit further controls the lighting circuit so that no current flows in the solid state light emitting device when the forward voltage detected by the forward voltage detection circuit is not within a predetermined range. You may have an abnormality determination part.

  The control circuit further includes a dimming control unit that controls the lighting circuit so that a current flowing through the solid state light emitting element changes depending on a dimming signal given from the outside, and the dimming control unit Depending on the forward voltage detected by the forward voltage detection circuit, the dimming characteristic which is the relationship between the dimming signal and the current flowing through the solid state light emitting device may be changed.

  At this time, as an example of the dimming characteristic, the dimming control unit may be configured such that the maximum value of the current flowing through the solid state light emitting device is smaller as the forward voltage detected by the forward voltage detection circuit is larger. The dimming characteristics may be changed depending on the forward voltage detected by the forward voltage detection circuit. Further, the dimming control unit further depends on a forward voltage detected by the forward voltage detection circuit, and a minimum value of a current flowing through the solid state light emitting element in the dimming characteristics, and the dimming You may change at least 1 of the inclination which is the ratio of the change of the electric current which flows into the said solid light emitting element with respect to the change of a signal.

  Here, the lighting circuit includes a switching element and an inductor connected in series with a DC voltage as an input, and a diode for regenerating energy stored in the inductor when the switching element is off. The control circuit may control the lighting circuit by controlling on / off of the switching element.

  In addition, this invention can be implement | achieved not only as a lighting device but as a lighting fixture provided with the said lighting device.

  ADVANTAGE OF THE INVENTION According to this invention, it is a lighting device corresponding to a different load, Comprising: Even when it is a case where a solid light emitting element with a big load is lighted, the lighting device which can suppress heat_generation | fever than before, and a lighting fixture provided with the same The

  Therefore, according to the present invention, lighting devices that can be widely applied to various types of lighting fixtures have been realized, and today, lighting fixtures including solid-state light emitting elements have become widespread, and the practical value of the present invention is extremely high.

FIG. 1 is a circuit diagram of a lighting device according to Embodiment 1 of the present invention. FIG. 2 is a diagram illustrating the operation of the Vf determination unit in the lighting device. FIG. 3 is a diagram showing a change over time of the output current from the lighting circuit in the soft start control. FIG. 4 is a circuit diagram of a lighting device in a modification of the first embodiment of the present invention. FIG. 5 is a diagram for explaining an example of output current control (constant output power) by the lighting device according to Embodiment 1 of the present invention. FIG. 6 is a diagram showing a result (output power is constant) obtained by the control shown in FIG. FIG. 7 is a diagram illustrating a procedure for determining the three control target values (Iout_x, Iout_y, Iout_z) of the “control signal” illustrated in FIG. 2. FIG. 8 is a diagram illustrating an example of another table (a table that enables abnormality determination) instead of the table illustrated in FIG. FIG. 9 is a circuit diagram of the lighting device according to Embodiment 2 of the present invention. FIG. 10 is a diagram illustrating examples of three types of dimming tables included in the dimming control unit in the lighting device. FIG. 11 is a diagram showing another example of three types of tables that replace the three types of tables shown in FIG. FIG. 12 is a diagram illustrating a configuration example of a lighting fixture according to Embodiment 3 of the present invention.

  Hereinafter, a lighting device and a lighting fixture according to the present invention will be specifically described with reference to the drawings. Note that each of the embodiments and modifications described below is a specific example of the present invention. The numerical values, shapes, materials, constituent elements, arrangement positions and connection forms of the constituent elements, operation timings, and the like shown in the following embodiments and modifications are merely examples, and are not intended to limit the present invention. In addition, among the constituent elements in the following embodiments and modifications, constituent elements that are not described in the independent claims indicating the highest concept are described as optional constituent elements.

(Embodiment 1)
First, the lighting device according to Embodiment 1 of the present invention will be described.

  FIG. 1 is a circuit diagram of lighting device 1 according to Embodiment 1 of the present invention. In this figure, not only the lighting device 1 but also a commercial power source 2 for supplying AC power to the lighting device 1 and a solid state light emitting element (here, LED 20, that is, one or more LED chips) to be lit. ) Are also illustrated (the same applies to other embodiments).

  The lighting device 1 is a lighting device corresponding to different loads (here, LEDs 20 having different forward voltages), and includes a rectifier circuit 3, a power factor correction circuit 4, a capacitor 5, a lighting circuit 10, a Vf detection circuit 25, And the control circuit 30 is provided. In the present specification, the “load” means an object to be turned on by the lighting device, that is, a solid light emitting element (in this embodiment, an LED, an LED chip, or an LED lamp as an example). . In addition, “different loads” means that the loads on the lighting device are different. For example, the forward voltage, which is a voltage drop across the solid state light emitting device when a current is applied to the solid state light emitting device, is different. means.

  The rectifier circuit 3 is a circuit that rectifies AC power supplied from the commercial power source 2 into DC power, and is, for example, a diode bridge for full-wave rectification.

  The power factor improvement circuit 4 is a circuit that improves the power factor of the lighting device 1, and is composed of, for example, a capacitor and a coil that also function as a noise filter.

  The capacitor 5 is a smoothing capacitor connected between the high potential output terminal and the low potential output terminal of the power factor correction circuit 4, and smoothes the pulsating DC voltage output from the power factor improvement circuit 4. To do.

  The lighting circuit 10 is an example of a circuit for passing a current to the LED 20 connected as a load of the lighting device 1. Here, a DC voltage generated at both ends of the capacitor 5 is used as an input to generate a current to flow to the LED 20. It is a chopper circuit that functions as a DC / DC converter. The lighting circuit 10 includes a drive unit 11, diodes 12 a and 12 b, a switching element 13, an inductor 14, a capacitor 15, and a resistor 16.

  The switching element 13 is a switching element that chops a DC voltage generated across the capacitor 5 and is, for example, an NMOS transistor. The drive unit 11 is a drive circuit that drives the switching element 13 in accordance with an input control signal (here, a switching signal). For example, the drive unit 11 is a circuit that generates a gate signal when the switching element 13 is an NMOS transistor. The diodes 12a and 12b are rectifying elements for regenerating energy stored in the inductor 14 in the circuit loop of the LED 20, the resistor 16, the diode 12b, and the inductor 14 when the switching element 13 is off. The inductor 14 is a regenerative coil for causing a current to flow through the LED 20 not only when the switching element 13 is on but also when it is off. The capacitor 15 is connected in parallel with the LED 20 and smoothes the voltage applied to the LED 20. The resistor 16 is connected in series with the LED 20 and is a resistor that detects a current flowing through the LED 20 (that is, an output current of the lighting circuit 10). The signal detected here (the voltage drop across the resistor 16) is input to the output control unit 31 as the detection signal b.

  The LED 20 is an example of a solid state light emitting device connected to the lighting device 1 as a load, and is, for example, one LED chip constituting an LED lamp or a plurality of LED chips connected in series.

  The Vf detection circuit 25 detects a forward voltage that is a voltage drop of the LED 20 when a current flows through the LED 20 (that is, a forward voltage Vf across one or more LED chips connected in series). It is an example of a voltage detection circuit. The Vf detection circuit 25 includes two resistors 26a and 26b connected in series. The two resistors 26a and 26b connected in series are connected between the high potential output terminal of the lighting circuit 10 and the reference potential of the lighting circuit 10 (that is, the potential at the low potential output terminal of the power factor correction circuit 4). ing. The two resistors 26a and 26b function as a voltage divider, and a signal (detection signal) corresponding to the forward voltage Vf of the LED 20 from a connection point of the two resistors 26a and 26b (that is, an output terminal of the Vf detection circuit 25). a) is output.

  The control circuit 30 is a circuit that controls the lighting circuit 10 such that a smaller current flows through the LED 20 as the forward voltage detected by the Vf detection circuit 25 increases, and includes an output control unit 31 and a Vf determination unit 32.

  Note that the relationship that “the smaller the forward voltage is, the smaller the current flows” is not limited to the case where such a relationship is continuously established in any region where the forward voltage can be taken. The case where such a relationship is established in the region is also included. For example, now, the Vf detection circuit 25 detects the first voltage as the forward voltage when the LED 20 is the first load, and sequentially detects when the LED 20 is the second load larger than the first load. Assume that a second voltage larger than the first voltage is detected as the direction voltage. At this time, the control circuit 30 controls the lighting circuit 10 so that the first current flows through the LED 20 when the forward voltage detected by the Vf detection circuit 25 is the first voltage. Then, when the forward voltage detected by the Vf detection circuit 25 is the second voltage, the control circuit 30 controls the lighting circuit 10 so that a second current smaller than the first current flows through the LED 20. To do.

  Based on the detection signal a sent from the Vf detection circuit 25, the Vf determination unit 32 determines a control target value corresponding to the forward voltage Vf of the LED 20 (that is, a control target value of the output current of the lighting circuit 10). Then, a control signal indicating the control target value is output to the output control unit 31. The Vf determination unit 32 determines a control target value so that a smaller output current is output from the lighting circuit 10 as the forward voltage Vf of the LED 20 is larger. This is to suppress heat generation in the lighting device 1 when an LED lamp with a large load is lit.

  FIG. 2 is a diagram illustrating an example of the operation of the Vf determination unit 32. Here, “detection signal a” input to the Vf determination unit 32, “load determination (type of load of the LED 20)” that is a determination result in the Vf determination unit 32, output from the Vf determination unit 32 to the output control unit 31. The correspondence relationship of the “control signal (control target value)” is shown in a table. In FIG. 2, the forward voltage indicated by “detection signal a” has a relationship of voltage V4> voltage V3> voltage V2> voltage V1. Further, as the load size in the “load determination”, there is a relationship of load Z> load Y> load X. Further, as a control target value indicated by the “control signal”, there is a relationship of current Iout_x> current Iout_y> current Iout_z>.

  For example, when the forward voltage of the LED 20 indicated by the input detection signal a is the voltage V1 to the voltage V2 (that is, the voltage V1 or more and less than the voltage V2), the Vf determination unit 32 applies the lighting device 1 to the lighting device 1. It is determined that the load of the attached LED 20 is the load X. As a result, the Vf determination unit 32 outputs a control signal indicating the current Iout_x as the control target value to the output control unit 31. Similarly, the Vf determination unit 32 determines that the LED 20 is the load Y when the forward voltage indicated by the detection signal a is the voltage V2 to the voltage V3 (that is, the voltage V2 or more and less than the voltage V3). Then, a control signal indicating the current Iout_y as a control target value is output to the output control unit 31. Similarly, the Vf determination unit 32 determines that the LED 20 is the load Z when the forward voltage indicated by the detection signal a is the voltage V3 to the voltage V4 (that is, the voltage V3 or more and less than the voltage V4). Then, a control signal indicating the current Iout_z as a control target value is output to the output control unit 31. As described above, the Vf determination unit 32 outputs a control signal to the output control unit 31 such that a smaller output current is output from the lighting circuit 10 as the forward voltage Vf of the LED 20 is larger.

  As an example of the timing for performing the above determination, the Vf determination unit 32 performs the determination immediately after the power is turned on. However, in the case where soft start control is performed such that the output current to the LED 20 is gradually increased after the power is turned on to turn on the LED 20, the Vf determination unit 32 determines that the output current as the initial value is applied to the LED 20 In addition, it is preferable to perform the above determination. FIG. 3 is a diagram illustrating an example of the relationship between the time after the power is turned on in the soft start control (horizontal axis) and the output current from the lighting circuit 10 (vertical axis). Here, the output current is set to the initial value Iout_a immediately after the power is turned on, and then gradually increases to the target value Iout_b with time after a certain time has elapsed. In such soft start control, it is preferable that the Vf determination unit 32 performs the above determination when the output current of the initial value Iout_a is applied to the LED 20. Thereby, after the power is turned on, the magnitude of the load of the LED 20 is determined when a predetermined output current (here, the initial value Iout_a) is applied to the LED 20, and the target value Iout_b suitable for the LED 20 is determined according to the determination result. Output current can be supplied.

  The output control unit 31 generates a switching signal such that the current flowing through the LED 20 (in other words, the output current from the lighting circuit 10) becomes a control target value indicated by the control signal sent from the Vf determination unit 32, Output to the drive unit 11. For this purpose, the output control unit 31 generates a PWM (Pulse Width Modulation) signal having a duty ratio such that the magnitude of the detection signal b indicating the voltage drop at the resistor 16 is constant (that is, the control target value). . Then, the output control unit 31 outputs the generated PWM signal to the drive unit 11 as a switching signal.

  Next, the operation of the lighting device 1 in the present embodiment configured as described above will be described.

  The AC voltage supplied from the commercial power source 2 is rectified by the rectifier circuit 3, subjected to processing for increasing the power factor by the power factor correction circuit 4, smoothed by the capacitor 5, and then applied to the lighting circuit 10. Supplied. The direct current voltage supplied to the lighting circuit 10 is converted into a desired direct current voltage by the lighting circuit 10 constituting the chopper circuit and applied to the LED 20 as a load. That is, in the lighting circuit 10, when the switching element 13 is turned on by the drive signal from the drive unit 11, a current flows through the LED 20 and the resistor 16 through the switching element 13, the diode 12 a, and the inductor 14. On the other hand, when the switching element 13 is turned off, the energy accumulated in the inductor 14 is regenerated in a circuit loop composed of the LED 20, the resistor 16 and the diode 12 b, and a current flows through the LED 20. As a result, the DC voltage supplied to the lighting circuit 10 is chopped in synchronization with the drive signal from the drive unit 11, but is smoothed by the capacitor 15 after chopping and applied to the LED 20.

  The forward voltage in the LED 20 is detected by the Vf detection circuit 25 and is output to the Vf determination unit 32 as the detection signal a. In the Vf determination unit 32, a control target value (that is, an output current of the lighting circuit 10) is determined according to the table shown in FIG. 2, and a control signal indicating the control target value is output to the output control unit 31. In the output control unit 31, a switching signal is generated such that the output current from the lighting circuit 10 becomes a control target value indicated by the control signal sent from the Vf determination unit 32, and is output to the drive unit 11. For example, when the forward voltage of the LED 20 connected to the lighting device 1 is small (for example, the load X), a PWM signal with a long duty for turning on the switching element 13 is output to the drive unit 11. On the other hand, when the forward voltage of the LED 20 connected to the lighting device 1 is large (for example, the load Z), a PWM signal with a reduced duty for turning on the switching element 13 is output to the drive unit 11. In the lighting circuit 10, DC / DC conversion is performed in accordance with a switching signal from the output control unit 31, and a constant (that is, control target value) current is supplied to the LED 20.

  Thus, a constant current determined according to the forward voltage of the LED 20 is supplied to the LED 20. At this time, as can be seen from the table shown in FIG. 2, constant current control is performed so that the smaller the forward voltage of the LED 20, the smaller the current flows through the LED 20. Thereby, compared with the conventional lighting device in which a constant current is supplied to the LED lamp regardless of the magnitude of the forward voltage in the LED lamp, heat generation in the lighting device when the LED lamp with a large load is lit is suppressed.

  In other words, according to the present embodiment, the output current from the lighting circuit 10 is suppressed as compared with the conventional LED lamp in which the power consumption increases due to the large forward voltage in the conventional constant current control. It is done. As a result, power consumption in the LED lamp is suppressed, and heat generation of circuit components constituting the lighting device 1 is suppressed. Therefore, thermal destruction of the lighting device is avoided, and in addition, adverse effects due to radiant heat from the lighting device are suppressed.

  Moreover, according to this Embodiment, since the forward voltage of LED20 becomes large, the output current to LED20 is reduced and the power consumption in LED20 is reduced, Therefore The heat_generation | fever of LED20 itself is also reduced. Therefore, deterioration due to the temperature rise of the LED 20 (that is, the LED chip) is reduced.

  Moreover, according to this Embodiment, with respect to LED20 with a large forward voltage, the heat_generation | fever in the lighting device 1 and the heat_generation | fever in LED20 are suppressed. Therefore, even when a lighting device is attached to a lighting fixture having a sealed structure with poor heat dissipation, an LED lamp with a large forward voltage can be made a compatible product, and it corresponds to various lighting fixture forms. A lighting device capable of the above is realized.

  In the present embodiment, the switching element 13 is connected to the high potential output terminal side of the power factor correction circuit 4, but the switching element 13 is connected to the power factor correction circuit 4 as in the modification shown in FIG. May be connected to the low potential output terminal side. In that case, the drive unit 11 in this embodiment is not necessary, and the switching element 13 can be directly driven by the switching signal from the output control unit 31. That is, in the lighting circuit 10a shown in FIG. 4, when the switching element 13 is turned on by the switching signal from the output control unit 31, a current flows through the diode 12a, the inductor 14, the LED 20, and the switching element 13. On the other hand, when the switching element 13 is turned off, the energy accumulated in the inductor 14 is regenerated in a circuit loop composed of the LED 20 and the diode 12b, and a current flows through the LED 20. Even in such a lighting circuit 10a, constant current control is performed such that a smaller current flows through the LED 20 as the forward voltage of the LED 20 is larger, as in the above embodiment.

  In the present embodiment, the Vf detection circuit 25 is composed of the two resistors 26a and 26b. However, the Vf detection circuit 25 is not limited to such a circuit, and any circuit can be used as long as it is a circuit that detects the output voltage of the lighting circuit 10. It may be. For example, the Vf detection circuit 25 may be configured only by wiring connected to the high potential output terminal of the lighting circuit 10.

  Further, in the present embodiment, the output control unit 31 and the Vf determination unit 32 are independent circuits, but these may be configured by one IC. This simplifies the circuit.

(Output current control example 1)
Next, a first specific example of current control that causes a smaller current to flow through the LED 20 as the forward voltage of the LED 20 increases, that is, an example of a specific operation of the control circuit 30 will be described.

  Here, the control circuit 30 has a smaller current flowing through the LED 20 as the forward voltage of the LED 20 increases, and the product of the forward voltage and the current flowing through the LED 20 without depending on the forward voltage (that is, The lighting circuit 10 is controlled so that the output power is constant.

  For this purpose, the Vf determination unit 32 makes the product of the forward voltage indicated by the detection signal a and the output current from the lighting circuit 10 based on the detection signal a sent from the Vf detection circuit 25 constant. Then, the control target value (that is, the output current of the lighting circuit 10) is determined. Then, the Vf determination unit 32 outputs a control signal indicating the determined control target value to the output control unit 31. Specifically, the Vf determination unit 32 is realized by a microcomputer or the like, and stores the relationship between the forward voltage (horizontal axis) and the control target value (vertical axis) as shown in FIG. 5 in a table or calculation formula. doing. The Vf determination unit 32 determines a control target value corresponding to the forward voltage indicated by the detection signal a by referring to the relationship, and outputs a control signal indicating the determined control target value to the output control unit 31. To do.

  As a result, the LED 20 is supplied to the LED 20 without depending on the forward voltage of the LED 20 as in the relationship between the forward voltage (horizontal axis) of the LED 20 and the output current (vertical axis) of the lighting circuit 10 shown in FIG. Power is maintained constant. Therefore, the power consumption of the LED 20, in other words, the light emission amount of the LED 20 is kept constant. Further, since the output power from the lighting device 1 is constant without depending on the load, the amount of heat generated in the lighting device 1 (that is, the component) is the same without depending on the load.

  Such control for making the output power from the lighting circuit 10 constant has the same brightness specification (that is, power consumption) for the various LED lamps attached to the lighting device 1, but the manufacturing companies and the like are different. Therefore, it is effective when the forward voltage is different. That is, even if the forward voltage of the LED lamp attached to the lighting device 1 is different, the power supplied to the LED lamp (that is, the brightness of the LED lamp) is kept the same.

  Also, such control can coexist with the control in the above embodiment. For example, in each range in the “detection signal a” shown in FIG. 2, the output current is changed depending on the forward voltage of the LED 20 around the control target value indicated by the corresponding “control signal”. The output power of the circuit 10 may be controlled to be constant. As an example, when the forward voltage indicated by the detection signal a is the voltage V1 to the voltage V2, the product of the forward voltage and the output current is always the average voltage ((V1 + V2) / 2) and the control target value. The Vf determination unit 32 may determine the control signal so as to be a product of (current Iout_x).

  Thereby, if it is an LED lamp with the same specification of power consumption, even if a forward voltage is different, the lighting device 1 which can ensure the same brightness is implement | achieved.

  In general, the LED 20 (that is, the LED chip) generally decreases in forward voltage and light output efficiency as the temperature rises. However, according to the control for keeping the output power constant, when the forward voltage decreases, control for increasing the output current from the lighting circuit 10 is performed. Therefore, the light output of the LED 20 is kept constant without depending on the temperature rise of the LED 20.

(Output current control example 2)
Next, a second specific example of current control that causes a smaller current to flow through the LED 20 as the forward voltage of the LED 20 is larger, that is, another example of the specific operation of the control circuit 30 will be described.

  Here, the control circuit 30 controls the lighting circuit 10 so that a smaller current flows through the LED 20 as the forward voltage of the LED 20 increases, and a light output of the LED 20 increases as the forward voltage increases. Therefore, the three control target values (Iout_x, Iout_y, Iout_z) of the “control signal” shown in FIG. 2 are set in advance so as to have the relationship shown in FIG.

  FIG. 7 is a diagram showing the relationship between the three control target values (Iout_x, Iout_y, Iout_z) of the “control signal” shown in FIG. 2, that is, a diagram for explaining the procedure for determining the three control target values. First, a desired current Iout_x is determined as a control target value corresponding to the load X whose forward voltage is the voltage V1 to the voltage V2.

  Next, a desired current Iout_y is determined in a range larger than the current Iout_y0 and smaller than the current Iout_x as a control target value corresponding to the load Y whose forward voltage is the voltage V2 to the voltage V3. Here, the current Iout_y0 is a current value that should flow through the load Y in order to obtain the same optical output as the optical output Lm1 of the load X when the current Iout_x flows through the load X. By setting such a current Iout_y as a control target value corresponding to the load Y, the following two points are satisfied. That is, first, the output current Iout_y from the lighting circuit 10 when the load Y is attached to the lighting device 1 is smaller than the output current Iout_x when the load X is attached to the lighting device 1. Second, the light output Lm2 when the load Y is attached to the lighting device 1 is larger than the light output Lm1 when the load X is attached to the lighting device 1.

  Subsequently, a desired current Iout_z is determined in a range larger than the current Iout_z0 and smaller than the current Iout_y as a control target value corresponding to the load Z whose forward voltage is the voltage V3 to the voltage V4. Here, the current Iout_z0 is a current value that should flow through the load Z in order to obtain the same optical output as the optical output Lm2 of the load Y when the current Iout_y flows through the load Y. By setting such a current Iout_z as a control target value corresponding to the load Z, the following two points are satisfied. That is, first, the output current Iout_z from the lighting circuit 10 when the load Z is attached to the lighting device 1 is smaller than the output current Iout_y when the load Y is attached to the lighting device 1. Second, the light output Lm3 when the load Z is attached to the lighting device 1 is larger than the light output Lm2 when the load Y is attached to the lighting device 1.

  The Vf determination unit 32 outputs a control signal indicating any one of the three control target values (Iout_x, Iout_y, Iout_z) set in this manner to the output control unit 31 according to the forward voltage of the LED 20. The following is realized. That is, the smaller the forward voltage of the LED 20, the smaller the current flows through the LED 20, and the greater the forward voltage, the greater the light output of the LED 20.

  Thereby, it is ensured that the light output from the LED lamp increases as the load of the LED lamp attached to the lighting device 1 increases. Therefore, even when a plurality of loads having different forward voltages (that is, LED lamps) are used as compatible loads and a load having a high forward voltage is used even when the load is replaced, a larger light output can be obtained. Function is secured.

  In the first embodiment, as shown in FIG. 2, it is determined which of the three types of loads is based on the forward voltage of the LED 20. In addition, the load is attached to the lighting device 1. It may also be determined whether the existing load is a conforming load.

  For example, the Vf determination unit 32 may operate according to the table shown in FIG. 8 instead of the table shown in FIG. In the table shown in FIG. 8, when the forward voltage indicated by the “detection signal a” is smaller than the voltage V1 or higher than the voltage V4, the “load determination” is “abnormal” and “ “Control signal” is registered to indicate “stop”. Thereby, the Vf determination unit 32 indicates that the load of the LED 20 attached to the lighting device 1 is abnormal when the forward voltage of the LED 20 indicated by the detection signal a is smaller than the voltage V1 or higher than the voltage V4. It is determined that there is (that is, no conforming load). As a result, the Vf determination unit 32 outputs a control signal (for example, a control signal indicating that the control target value (output current from the lighting circuit 10) is zero) instructing the stop of the operation of the lighting circuit 10 to the output control unit. To 31. Upon receiving the control signal, the output control unit 31 outputs a switching signal that stops (eg, turns off) the switching element 13 to the drive unit 11. Thereby, the operation of the lighting circuit 10 is stopped, and the output current from the lighting circuit 10 becomes zero.

  That is, in addition to the function in the above embodiment, the control circuit 30 controls the lighting circuit 10 so that no current flows through the LED 20 when the forward voltage detected by the Vf detection circuit 25 is not within a predetermined range. You may have the abnormality determination part to control. Thereby, when the forward voltage of the load attached to the lighting device 1 is out of a certain range, it is determined that an abnormal load is attached to the lighting device 1, and the operation of the lighting circuit 10 is stopped. Therefore, when an incorrect load (non-conforming load) is attached to the lighting device 1 or when the load becomes abnormal due to a failure or the like, the operation of the lighting device is automatically stopped to ensure safety. The

(Embodiment 2)
Next, a lighting device according to Embodiment 2 of the present invention will be described.

  FIG. 9 is a circuit diagram of lighting device 1a according to Embodiment 2 of the present invention. This lighting device 1a has a dimming function in addition to the functions of the lighting device 1 of the first embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In addition, the light control part 34 which outputs a light control signal to the lighting device 1a is also shown in the figure. The dimming signal is a signal that designates an output current from the lighting device 1a (that is, the light output of the LED 20), and is, for example, a DC voltage or a PWM signal (that is, a rectangular wave having a variable duty). In the present embodiment, the dimming signal will be described below assuming that it is a PWM signal.

  In addition to the functions in the first embodiment, the control circuit 30 (more strictly speaking, the Vf determination unit 32a) of the lighting device 1a includes a dimming control unit 33.

  The dimming control unit 33 controls the lighting circuit 10 (that is, the on / off state of the switching element 13) so that the current flowing through the LED 20 changes depending on the dimming signal given from the outside (here, the dimming unit 34). To do. At this time, the dimming control unit 33 depends on the forward voltage detected by the Vf detection circuit 25 to adjust the dimming characteristics that are the relationship between the dimming signal and the current flowing through the LED 20 (that is, the control target value). Change.

  Specifically, the dimming control unit 33 holds a dimming table (here, three types of dimming tables) indicating dimming characteristics corresponding to the type of load. Then, the dimming control unit 33 determines the type of load attached to the lighting device 1 based on the forward voltage detected by the Vf detection circuit 25, and creates a dimming table corresponding to the determined type of load. select. By referring to the selected dimming table, the dimming control unit 33 uses the control target value corresponding to the dimming signal from the dimming unit 34 as a control signal from the Vf determination unit 32a to the output control unit 31. Output to the output control unit 31.

  FIG. 10 is a diagram illustrating an example of dimming characteristics indicated by the three types of dimming tables included in the dimming control unit 33. 10A, 10B, and 10C show dimming tables (that is, dimming characteristics) corresponding to the load X, the load Y, and the load Z, respectively. In each dimming table, the horizontal axis represents the duty of the dimming signal from the dimming unit 34, and the vertical axis represents the control target value (that is, the output current from the lighting circuit 10).

  As can be seen from FIG. 10, the upper limit value of the control target value corresponding to the smallest load X is the current Iout_x, the upper limit value of the control target value corresponding to the next largest load Y is the current Iout_y, and the largest load Z The upper limit value of the control target value corresponding to is the current Iout_z. Note that the relationship between the three currents Iout_x, Iout_y, and Iout_z is Iout_x> Iout_y> Iout_z as described above. That is, the dimming control unit 33 sets the forward voltage detected by the Vf detection circuit 25 so that the maximum value of the current flowing through the LED 20 becomes smaller as the forward voltage detected by the Vf detection circuit 25 becomes larger. Depending on the dimming characteristics.

  Note that the lower limit value of the control target value is the same value (here, current Iout_min) in any dimming table. Further, the gradient (the gradient in the dimming characteristics) in the change of the control target value with respect to the duty of the dimming signal is the same in any dimming table.

  According to the lighting device 1a in the present embodiment including such a light control unit 33, a light control table corresponding to various loads is selected, and light control is performed according to the selected light control table. Therefore, fine dimming control according to the electrical characteristics of the load becomes possible.

  In each dimming table, the upper limit value of the current flowing to the load is set to a smaller current value as the load is larger. When the light is adjusted to the maximum brightness, a smaller current flows to the load as the load is larger. To be controlled. Therefore, also in the present embodiment, the same effect as in the first embodiment can be obtained.

  Furthermore, in this embodiment, the gradient of the dimming characteristics in each dimming table (that is, the gradient that is the ratio of the change in the current flowing through the LED 20 with respect to the change in the dimming signal) is set to be the same regardless of the load size. Has been. Therefore, when the operator gradually increases the dimming degree in the operation at the dimming unit 34, the LED 20 is brightened at the same rate of change regardless of the type of load. Therefore, even when the load attached to the lighting device 1 is replaced, unified operability is ensured.

  In addition, as a kind of the light control table which the light control part 33 has, it is not limited to what is shown by FIG. For example, a dimming table showing the characteristics shown in FIG. 11 may be employed.

  FIG. 11 is a diagram illustrating another example of three types of dimming tables (that is, dimming characteristics) included in the dimming control unit 33 according to the modification of the present embodiment. (A), (b), and (c) of FIG. 11 show dimming tables (that is, dimming characteristics) corresponding to the load X, the load Y, and the load Z, respectively. The point that the upper limit value of the control target value is smaller as the load is larger is the same as the dimming table in FIG.

  However, in the dimming table shown in FIG. 10, only the upper limit value of the control target value differs for each load. However, in the dimming table shown in FIG. 11, not only the upper limit value of the control target value but also the control target value. The lower limit of the value and the slope in the dimming characteristics are also different for each load. That is, the dimming control unit 33 determines at least one of the minimum value of the current flowing through the LED 20 and the gradient in the dimming characteristic in the dimming characteristic depending on the forward voltage detected by the Vf detection circuit 25. Change.

  With such a feature, according to the dimming table shown in FIG. 11, the output current of the lighting circuit 10 can be set finely for each load as compared with the dimming table shown in FIG. Therefore, at the time of dimming, fine current control in accordance with the electrical characteristics of the load becomes possible.

(Embodiment 3)
Next, the lighting fixture in Embodiment 3 of this invention is demonstrated.

  The lighting fixture in this Embodiment is provided with the lighting device in any one of the said Embodiment 1, 2 and modification.

  (A) of FIG. 12 is a figure which shows an example of the lighting fixture in this Embodiment, ie, the structure of the lighting fixture 40 of the power supply installation type which has arrange | positioned the lighting device 51 separately from the light source part 53. In FIG. The luminaire 40 includes a lighting device 51, a light source unit 53, and a lead wire 57 that connects them. Here, a state in which the instrument body 50 that houses the light source unit 53 is embedded in the ceiling 58 is shown. In the following description, the expressions “upper” and “lower” mean the upper direction and the lower direction in FIG.

  The instrument body 50 is made of a metal such as aluminum die casting, for example, and is formed in a bottomed cylindrical shape having an open lower end. A light source unit 53 including a plurality of (in the drawing, three) LEDs 20 and a substrate 54 on which each LED 20 is mounted is disposed on the upper bottom portion inside the instrument body 50. Each LED 20 is arranged so that the light irradiation direction is downward in order to irradiate the external space with light from the lower end of the instrument body 50. In addition, a translucent plate 56 for diffusing light from each LED 20 is provided in the opening at the lower end of the instrument body 50. On the back surface (upper surface) of the ceiling 58, the lighting device 51 is disposed at a place different from the fixture body 50. The lighting device 51 and the light source unit 53 are wired with a lead wire 57 via a connector 60.

  The lighting device 51 is a device that houses any one of the lighting devices of the first and second embodiments and the modified examples.

  FIG. 12B is a diagram illustrating another example of the lighting fixture in the present embodiment, that is, a configuration of a power supply-integrated lighting fixture 41 in which the lighting device 51 is built in the fixture main body 50 together with the light source unit 53. . In this configuration, a heat radiating plate 61 made of an aluminum plate or a copper plate is disposed on the upper surface of the substrate 54 in contact with the instrument body 50. Thereby, the heat generated in each LED 20 can be released to the outside through the heat radiating plate 61 and the instrument main body 50.

  As described above, according to the lighting device and the lighting fixture in the above-described embodiment and modification, control is performed such that a smaller current flows through the LED 20 as the forward voltage Vf of the LED 20 increases. Therefore, even when a solid light-emitting element such as an LED lamp with a large load is lit, a lighting device and a lighting fixture that can suppress heat generation compared to the related art are realized.

  As mentioned above, although the lighting device and lighting fixture which concern on this invention were demonstrated based on embodiment and its modification, this invention is not limited to these embodiment and modification. As long as it does not deviate from the gist of the present invention, various modifications conceived by those skilled in the art are applied to the present embodiments and modifications, and forms constructed by combining components in different embodiments and modifications are also included in the present invention. Within one or more embodiments.

  For example, in the above-described embodiment, three types (load X, load Y, load Z) are shown as the types of loads that are determined by the lighting device. However, the types of loads that are determined are limited to such numbers. Not. The lighting device according to the present invention may determine two types or four or more types of loads and change the output current according to the determined types of loads.

  Moreover, in the said embodiment, although the lighting circuits 10 and 10a had the capacitor | condenser 15 for smoothing, it does not necessarily need to have such a capacitor | condenser. This is because, when the switching frequency at which the switching element 13 is turned on and off is higher than a certain level, even if a high-frequency pulsating current flows through the LED 20, the flickering of the light emission of the LED 20 is not perceived by human eyes.

  In the above embodiment, two types of chopper circuits are shown as the lighting circuits 10 and 10a. However, the chopper circuits are not limited to such types. The lighting circuits 10 and 10a may be realized by any type of chopper circuit such as a step-up type, a step-down type, and a step-up / down type chopper circuit. Furthermore, the lighting circuits 10 and 10a are not limited to chopper circuits. Any circuit may be used as long as it is an externally controllable current source that can control the current output to the LED 20 under the control of the control circuit 30.

  Moreover, in the said embodiment, although the lighting device 1 was driven with the alternating current power from the commercial power source 2, you may drive with the direct current power from a battery, a power generator, etc. FIG. In such a case, the rectifier circuit 3, the power factor correction circuit 4, the capacitor 5, and the like are not necessary.

  In the above embodiment, the LED 20 is employed as the solid light emitting element, but a solid light emitting element such as a semiconductor laser, an organic EL (Electro Luminescence), or an inorganic EL may be employed.

  INDUSTRIAL APPLICABILITY The present invention can be used as a lighting device for lighting a solid light emitting element such as a light emitting diode (LED) and a lighting fixture using the same. In particular, the present invention is a lighting device corresponding to different loads, and can be used as a lighting device and a lighting fixture that can suppress heat generation as compared with the related art even when a solid light emitting element with a large load is turned on. For example, the present invention can be used as a lighting device and a lighting fixture for an LED lamp.

DESCRIPTION OF SYMBOLS 1, 1a, 51 Lighting device 2 Commercial power supply 3 Rectifier circuit 4 Power factor improvement circuit 5, 15 Capacitor 10, 10a Lighting circuit 11 Drive part 12a, 12b Diode 13 Switching element 14 Inductor 16, 26a, 26b Resistance 20 LED
25 Vf detection circuit 30 Control circuit 31 Output control unit 32, 32a Vf determination unit 33 Dimming control unit 34 Dimming unit 40, 41 Lighting fixture 50 Instrument body 53 Light source unit 54 Substrate 56 Translucent plate 57 Lead wire 58 Ceiling 60 Connector 61 Heat sink

Claims (10)

A lighting device for different loads,
A lighting circuit for passing a current to the solid state light emitting device connected to the lighting device as the load;
A forward voltage detection circuit that detects a forward voltage that is a voltage drop of the solid state light emitting device when a current flows through the solid state light emitting device;
A control circuit that controls the lighting circuit so that a smaller current flows through the solid state light emitting element as the forward voltage detected by the forward voltage detection circuit increases .
The control circuit sets the lighting circuit so that the current flowing through the solid state light emitting element becomes a predetermined initial value immediately after the lighting device is turned on and then increases to a target value with time. A lighting device that controls and determines the target value corresponding to the forward voltage detected by the forward voltage detection circuit when the current is the initial value . The forward voltage detection circuit detects a first voltage as the forward voltage when the solid state light emitting element is a first solid state light emitting element, and the solid state light emitting element is detected by the first solid state light emitting element. A second voltage greater than the first voltage is detected as the forward voltage when the second solid-state light emitting device has a large load.
The control circuit controls the lighting circuit so that a first current flows through the solid state light emitting device when the forward voltage detected by the forward voltage detection circuit is the first voltage, When the forward voltage detected by the forward voltage detection circuit is the second voltage, the lighting circuit is controlled so that a second current smaller than the first current flows through the solid state light emitting device. The lighting device according to claim 1. In the control circuit, the larger the forward voltage detected by the forward voltage detection circuit, the smaller the current flows through the solid state light emitting device, and the control circuit depends on the forward voltage detected by the forward voltage detection circuit. The lighting device according to claim 1 or 2, wherein the lighting circuit is controlled so that a product of a forward voltage detected by the forward voltage detection circuit and a current flowing through the solid state light emitting element is constant. In the control circuit, as the forward voltage detected by the forward voltage detection circuit increases, a smaller current flows through the solid-state light emitting element, and as the forward voltage detected by the forward voltage detection circuit increases, The lighting device according to claim 1, wherein the lighting circuit is controlled so that a light output of the solid state light emitting device is increased. The control circuit further includes an abnormality determination unit that controls the lighting circuit so that no current flows through the solid state light emitting device when the forward voltage detected by the forward voltage detection circuit is not within a predetermined range. The lighting device according to any one of claims 1 to 4. The control circuit further includes a dimming control unit that controls the lighting circuit so that a current flowing through the solid state light emitting device changes depending on a dimming signal given from the outside,
The dimming control unit changes a dimming characteristic that is a relationship between the dimming signal and a current flowing through the solid state light emitting device, depending on a forward voltage detected by the forward voltage detection circuit. The lighting device according to any one of? The dimming control unit is detected by the forward voltage detection circuit such that the maximum value of the current flowing through the solid state light emitting element is smaller as the forward voltage detected by the forward voltage detection circuit is larger. The lighting device according to claim 6, wherein the dimming characteristic is changed depending on a forward voltage. The dimming control unit further depends on the forward voltage detected by the forward voltage detection circuit, and the minimum value of the current flowing through the solid-state light emitting element in the dimming characteristics, and the dimming signal The lighting device according to claim 7, wherein at least one of inclinations, which is a rate of change of current flowing through the solid state light emitting device with respect to change, is changed. The lighting circuit includes a DC voltage as an input, and includes a switching element and an inductor connected in series, and a diode for regenerating energy stored in the inductor when the switching element is OFF,
The lighting device according to claim 1, wherein the control circuit controls the lighting circuit by controlling on / off of the switching element.   A lighting fixture comprising the lighting device according to any one of claims 1 to 9.

Images