JP2007234415A - Power supply circuit for lighting, and luminaire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply circuit for lighting, and a luminaire capable of smoothly changing brightness of a light emitting diode. <P>SOLUTION: The luminaire is provided with a DC power supply part 27 for outputting power for light emission to a light emitting part 3, a constant current circuit 28 for adjusting a load current flowing in the light emitting part 3 based on DC power output from the DC power supply part 27, and a light controlling part 29 for outputting the DC power in response to a light control signal to the light emitting part 3 by the DC power supply part 27 when the light control signal S1 indicates the current value exceeding the previously set current value, and adjusting a load current IL to a current value in response to the light control signal by the constant current circuit 28 when the light control signal indicates a current value which is less than a set current value. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lighting power supply circuit that emits light from a light-emitting diode, and a lighting fixture using the same.

  FIG. 15 is a block diagram illustrating a configuration of an illumination power supply circuit 102 according to the background art and a lighting fixture 101 using the illumination power supply circuit 102 (see, for example, Patent Document 1). A lighting fixture 101 shown in FIG. 15 is a lighting fixture using a light emitting diode, and is attached to, for example, an indoor ceiling, and includes a lighting power supply circuit 102 and a light emitting unit 103. The illumination power supply circuit 102 shown in FIG. 15 includes a diode bridge 104 that receives commercial AC power supply voltage, performs full-wave rectification, and applies it to both ends of the smoothing capacitor 105. One end of the capacitor 105 is connected to the collector of the transistor 107 via the primary winding of the transformer 106, and the emitter of the transistor 107 is connected to the other end of the capacitor 105.

  One end of the secondary winding of the transformer 106 is connected to the other end of the secondary winding of the transformer 106 via a diode 108 and a smoothing capacitor 109. One end of the capacitor 109 is connected to the other end of the capacitor 109 via a light emitting unit 103 and a resistor 110 connected to the outside of the illumination power supply circuit 102. The light emitting unit 103 is configured by, for example, two light emitting diodes connected in series.

For example, a dimming signal output from a dimmer 112 attached to an indoor wall surface is input to a PWM (Pulse Width Modulation) circuit 111, and the PWM circuit 111 turns on and off the transistor 107 according to the dimming signal. By adjusting the duty ratio, the current flowing through the light emitting unit 103 is adjusted, and the brightness of the light emitting unit 103 is adjusted.
JP-A-2005-294063

  By the way, since light emitting diodes have higher emission brightness than light emitters such as incandescent lamps and fluorescent lamps, even when light is emitted with the same luminous flux as incandescent lamps and fluorescent lamps, it is brightly lit for the user. It is recognized that Therefore, in order to make the apparent brightness the same as that of an incandescent lamp or a fluorescent lamp, it is necessary to suppress the driving current and reduce the luminous flux. In addition, when performing a fade-in operation in which the drive current is gradually increased over time and a fade-in operation in which the drive current is gradually decreased and turned off is performed, in order to smoothly change the brightness of the light emitting diode The drive current needs to be controlled in a wide range from a very small current value to a rated current value in all lighting states.

  However, in order to make the apparent brightness the same as that of an incandescent lamp or a fluorescent lamp, the lower limit of the current control range is set, for example, when a lighting fixture is configured with one or a plurality of light emitting diodes with a rated current of 350 mA. Although it is necessary to set the value to several μA to several mA or less, the above-described illumination power supply circuit 102 is difficult to control the current of a minute current. In order to smoothly change the brightness of the light emitting diode, for example, when the rated current of the light emitting diode is 350 mA, it is necessary to adjust the driving current in a current range of about 100 μA to 350 mA, which is about 1/1000. Since the driving current must be controlled with the current resolution of the above, the above-described illumination power supply circuit 102 has a disadvantage that it is difficult to smoothly change the brightness of the light emitting diode.

  The present invention has been made in view of such a problem, and provides an illumination power supply circuit capable of lighting a light emitting diode with low brightness or smoothly changing the brightness. Objective. And it aims at providing the lighting fixture using such a power supply circuit for illumination.

  In order to achieve the above object, a lighting power supply circuit according to a first means of the present invention includes first and second connection terminals for connecting a light emitting unit using a light emitting diode, and brightness of the light emitting unit. A dimming signal supply unit that receives a dimming instruction for instructing the light intensity and supplies a dimming signal indicating a load current to flow between the first and second connection terminals according to the dimming instruction; and the light emitting unit A DC power source for outputting power for light emission, a current regulator for adjusting a load current flowing between the first and second connection terminals based on the DC power output from the DC power source, and When the dimming signal supplied from the dimming signal supply unit indicates a current value that exceeds a preset current value, the DC power supply unit supplies DC power corresponding to the dimming signal to the first and second connections. Output between the terminals, and the dimming signal When showing a current value less than the value, the by the current adjusting unit, the load current, is characterized in that it comprises a corresponding dimming signal dimming control unit for adjusting the current value corresponding to.

  In the illumination power supply circuit described above, when the dimming signal supply unit receives a dimming instruction to turn off the light emitting unit, the dimming signal supply unit changes the dimming signal to gradually reduce the load current. It is characterized by that.

  In the illumination power supply circuit described above, when the dimming signal supply unit receives a dimming instruction to turn on the light emitting unit, the dimming signal supply unit changes the dimming signal to gradually increase the load current. It is characterized by that.

  In the illumination power supply circuit described above, the current adjustment unit is a constant current circuit connected in series with the first and second connection terminals, and the dimming control unit is configured so that the dimming signal is the setting. When a current value less than the current value is indicated, the DC power supply unit outputs a preset setting voltage to a series circuit of the first and second connection terminals and the constant current circuit, and the constant current circuit A load current corresponding to the dimming signal is allowed to flow.

  Moreover, in the above-described illumination power supply circuit, the current adjustment unit is a switching element connected in series with the first and second connection terminals, and the dimming control unit is configured such that the dimming signal has the set current. When the current value less than the value is indicated, the DC power supply unit outputs a preset setting voltage to the series circuit of the first and second connection terminals and the switching element, and is indicated by the dimming signal. The on / off duty ratio of the switching element is increased / decreased according to the increase / decrease of the current value.

  In the illumination power supply circuit described above, the current adjustment unit is a constant current circuit connected between the first and second connection terminals, and the dimming control unit is configured such that the dimming signal has the set current. When the current value less than the value is indicated, the DC power supply unit outputs a predetermined constant current between the first and second connection terminals, and increases or decreases the current value indicated by the dimming signal. Accordingly, the current flowing through the constant current circuit is decreased.

  In the illumination power supply circuit described above, the current adjusting unit is a variable resistor connected between the first and second connection terminals, and the dimming control unit is configured such that the dimming signal has the set current value. When the current value less than 1 is indicated, the DC power supply unit outputs a constant current preset between the first and second connection terminals and responds to an increase or decrease in the current value indicated by the dimming signal. The resistance value of the variable resistor is increased or decreased.

  In the illumination power supply circuit, the current adjusting unit is connected between the first and second connection terminals and charged by an output voltage of the DC power supply unit, and the capacitor is connected to the DC power supply. The dimming control unit is configured to switch the capacitor to the DC power source by the switching element when the dimming instruction to turn off the light emitting unit is received by the dimming instruction receiving unit. It is characterized by being separated from the part.

  And the lighting fixture which concerns on the 2nd means of this invention is equipped with the power supply circuit for illumination in any one of the above-mentioned, and the light emission part connected between the said 1st and 2nd connection terminal, It is characterized by the above-mentioned. Yes.

  In the illumination power supply circuit and the lighting fixture having such a configuration, the dimming control unit has a current value that exceeds the preset current value of the dimming signal according to the dimming instruction that instructs the brightness of the light emitting unit. When the DC power source unit outputs DC power corresponding to the dimming signal between the first and second connection terminals, and the dimming signal exhibits a current value less than the set current value, the current adjustment unit The load current is adjusted to a current value corresponding to the dimming signal. Thereby, the load current is adjusted by the DC power supply unit for the current range where the load current is large, and the light emitting unit is made bright according to the dimming instruction, and the load current is adjusted by the current adjustment unit for the current range where the load current is small. Since the light emitting unit is adjusted to be bright according to the dimming instruction, the load current can be adjusted by the current adjusting unit even in the range where the load current is difficult to adjust in the DC power supply unit, The light emitting diode can be turned on with low brightness, or the brightness of the light emitting diode can be changed smoothly.

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

(First embodiment)
FIG. 1 is a circuit diagram for explaining an example of the configuration of a lighting fixture using the lighting power supply circuit according to the first embodiment of the present invention. A lighting fixture 1 shown in FIG. 1 is attached to, for example, an indoor ceiling, and includes a lighting power supply circuit 2 and a light emitting unit 3. The illumination power supply circuit 2 shown in FIG. 1 includes power supply connection terminals 21 and 22 that receive commercial AC power supply voltage, a control terminal 23 (a dimming instruction receiving unit), and external connection terminals 24 and 25 (first and second). Connection terminal), a DC power supply unit 27, a constant current circuit 28 (current adjustment unit), and a dimming control unit 29.

  The DC power supply unit 27 includes a diode bridge DB that applies full-wave rectification to the commercial AC power supply voltage received at the power supply connection terminals 21 and 22 and applies it to both ends of the smoothing capacitor C1. One end of the capacitor C1 is connected to the collector of the transistor Tr1 via the primary winding n1 of the transformer T, and the emitter of the transistor Tr1 is connected to the other end of the capacitor C1.

  One end of the secondary winding n2 of the transformer T is connected to the other end of the secondary winding n2 via a diode D1 and a smoothing capacitor C2. One end of the capacitor C2 is connected to the external connection terminal 24, and the other end of the capacitor C2 is connected to the external connection terminal 25 via the resistor R1.

  For example, the dimming signal S1 output from the dimmer 4 attached to the indoor wall surface is received by the control terminal 23 and supplied to the dimming control unit 29. The dimming signal S1 is a signal indicating the current value of the load current IL to be passed through the light emitting unit 3, that is, the brightness of the light emitting unit 3. In this case, the dimming signal S1 indicates a dimming instruction that indicates the brightness of the light emitting unit, and is also used as a dimming signal that indicates the load current IL of the light emitting unit 3, and the control terminal 23 supplies the dimming signal. This corresponds to an example of a section.

  The PWM circuit 26 is a control circuit that sets the on / off duty ratio of the transistor Tr1 according to the control signal S21 from the dimming control unit 29 and sets the voltage generated across the capacitor C2. The diode bridge DB, the capacitors C1 and C2, the transformer T, the transistor Tr1, the diode D1, and the PWM circuit 26 constitute a DC power supply unit 27 that is a switching power supply circuit. In this case, the voltage generated across the capacitor C2 becomes the output voltage Vout of the DC power supply unit 27.

  The external connection terminals 24 and 25 are connection terminals for connecting the light emitting unit 3 and output the power output from the illumination power supply circuit 2 to the light emitting unit 3. The light emitting unit 3 is configured by, for example, two light emitting diodes connected in series. The light emitting unit 3 may be a single light emitting diode, a plurality of light emitting diodes connected in series, or a plurality of light emitting diodes connected in parallel.

  The external connection terminal 25 is connected to the collector of the transistor Tr2, and the emitter of the transistor Tr2 is connected to the other end of the capacitor C2 via the resistor R2. The other end of the capacitor C2 is connected to the negative electrode of the DC voltage source E1 whose output voltage is variable, the positive electrode of the DC voltage source E1 is connected to the non-inverting amplifier terminal of the operational amplifier 281, and the output terminal of the operational amplifier 281 is a transistor. The emitter of the transistor Tr2 is connected to the inverting amplification terminal of the operational amplifier 281. The DC voltage source E1, the operational amplifier 281, the transistor Tr2, and the resistors R1 and R2 constitute a constant current circuit 28 in which the output current is variable. The DC voltage source E1 changes the output voltage according to the control signal S22 from the dimming control unit 29, and changes the output current of the constant current circuit 28.

  The dimming control unit 29 is a control circuit configured using, for example, a comparator or a logic circuit, and the minimum output current that the current value of the load current IL indicated by the dimming signal S1 can be output in terms of the performance of the DC power supply unit 27. When the current value exceeds the preset minimum output current Imin (set current value) as a value (minimum controllable limit current value), the control signal S21 is output to the PWM circuit 26, and the DC power supply unit 27 A direct current corresponding to the dimming signal S1 is output to the light emitting unit 3 as the load current IL via the external connection terminals 24 and 25 and the constant current circuit 28.

  On the other hand, when the dimming signal S1 indicates a current value that is less than the minimum output current Imin, the dimming control unit 29 outputs the control signal S21 to the PWM circuit 26, and the output voltage Vout of the DC power supply unit 27 is emitted, for example, The on / off duty ratio of the transistor Tr1 is set so that the setting voltage V1 set in advance as a voltage for causing the minimum output current Imin to flow through the unit 3 is set. As a result, when the load current IL indicated by the dimming signal S1 becomes equal to or less than the minimum output current Imin, the output voltage of the DC power supply unit 27 is set to the set voltage V1. Further, the dimming control unit 29 outputs a control signal S22 to the DC voltage source E1, and the constant current circuit 28 causes the DC current corresponding to the dimming signal S1 to be supplied to the external connection terminals 24 and 25 and the constant current circuit 28. And output to the light emitting unit 3 as a load current IL.

  Next, operation | movement of the lighting fixture 1 comprised as mentioned above is demonstrated. FIG. 2 is an explanatory diagram for explaining an operation when the light emitting unit 3 is gradually turned off in the lighting fixture 1. 2A shows the dimming signal S1 output from the dimmer 4, FIG. 2B shows the output voltage Vout of the DC power supply unit 27, and FIG. 2C shows the load flowing through the light emitting unit 3. Current IL is shown.

  First, when the dimming signal S1 output from the dimmer 4 indicates the full lighting state, the output voltage Vout is set to the voltage VF, the load current IL flowing through the light emitting unit 3 is set to the current IF, and the light emitting unit 3 Is fully lit. Next, after timing T1, the dimmer 4 is operated by the user so as to gradually darken the light emitting unit 3, and the dimming signal S1 gradually decreases.

  Then, the dimming control unit 29 outputs the control signal S21 to the PWM circuit 26 in order to reduce the output voltage Vout of the DC power supply unit 27 according to the dimming signal S1 and to reduce the load current IL. Next, the PWM circuit 26 reduces the on-duty ratio of the transistor Tr1 according to the control signal S21, and as a result, the output voltage Vout decreases. As a result, the load current IL decreases according to the control signal S21. Decreases.

  Next, at timing T2, when the dimming signal S1 reaches the signal level Lmin indicating the minimum output current Imin, the output voltage Vout of the DC power supply unit 27 is set to the set voltage V1 according to the control signal S21 from the dimming control unit 29. Set to Further, after timing T2, the dimming control unit 29 outputs a control signal S22 to the DC voltage source E1 to reduce the load current IL according to the dimming signal S1, and the output current of the constant current circuit 28 is reduced. As a result, the load current IL is reduced according to the dimming signal S1. At timing T3, the load current IL becomes zero, the light emitting unit 3 is turned off, and the output voltage Vout of the DC power supply unit 27 is set to zero according to the control signal S21 from the dimming control unit 29.

  FIG. 3 is an explanatory diagram for explaining an operation when the light emitting unit 3 is gradually brightened and lit in the lighting fixture 1. 3A shows the dimming signal S1 output from the dimmer 4, FIG. 3B shows the output voltage Vout of the DC power supply unit 27, and FIG. 3C shows the load flowing through the light emitting unit 3. Current IL is shown.

  First, at timing T4, when the dimming signal S1 output from the dimmer 4 shifts from the extinguished state to a slightly lit state, the direct current power supply unit 27 receives the control signal S21 from the dimming control unit 29. The output voltage Vout is set to the set voltage V1. Next, when the dimming signal S1 gradually rises, the dimming control unit 29 outputs a control signal S22 to the DC voltage source E1 to increase the load current IL in accordance with the dimming signal S1, and the constant current circuit 28 As a result of the increase in the output current, the load current IL is increased in accordance with the dimming signal S1, and the light emission luminance of the light emitting unit 3 gradually increases.

  Next, at timing T5, when the dimming signal S1 reaches the signal level Lmin indicating the minimum output current Imin, the output voltage Vout of the DC power supply unit 27 is increased according to the control signal S21 from the dimming control unit 29, and the load The current IL increases according to the output voltage Vout, and the light emission luminance of the light emitting unit 3 gradually increases. At timing T6, the output voltage Vout of the DC power supply unit 27 is set to the voltage VF, the load current IL flowing through the light emitting unit 3 is set to the current IF, and the light emitting unit 3 is fully turned on.

  As described above, in both cases where the light emitting unit 3 is gradually darkened from the fully lit state and turned off, and the light source unit 3 is gradually lightened from the turned off state and fully lit, the load current IL is In the current range that is less than the minimum output current Imin, the constant current circuit 28 causes the load current IL to flow through the light emitting unit 3. Therefore, the light emitting unit has a current range that does not satisfy the minimum output current Imin of the DC power supply unit 27. 3 can be dimmed, and the light emitting unit 3 can be lighted with low brightness, or the brightness of the light emitting unit 3 can be changed smoothly.

(Second Embodiment)
Next, the lighting fixture 1a using the power supply circuit 2a for illumination which concerns on the 2nd Embodiment of this invention is demonstrated. FIG. 4 is a circuit diagram showing an example of the configuration of the illumination power supply circuit 2a according to the second embodiment of the present invention. The illumination power supply circuit 2a shown in FIG. 4 is different from the illumination power supply circuit 2 shown in FIG. 1 in that the illumination power supply circuit 2a further includes a dimming signal supply unit 30. Further, the switch 5 is connected to the control terminal 23, and the dimming instruction signal S3 which is an on / off signal of the switch 5 is a dimming instruction for turning off the light emitting unit 3, and that the light emitting unit 3 is turned on. The dimming instruction is received by the control terminal 23 and received by the dimming signal supply unit 30.

  When the switch 5 is turned off by the user and a dimming instruction for turning off the light emitting unit 3 is received, the dimming signal supply unit 30 reduces the dimming signal S1 to gradually decrease the load current IL. When the switch 5 is turned on by the user and a dimming instruction for turning on the light emitting unit 3 is received, the dimming signal S1 is increased to gradually increase the load current IL.

  Since the other configuration is the same as that of the lighting fixture 1 shown in FIG. 1, the description thereof is omitted, and the operation of the present embodiment will be described below. FIG. 5 is an explanatory diagram for explaining an operation when the light emitting unit 3 is turned off in the lighting fixture 1a. 5A shows the dimming instruction signal S3 output from the switch 5 and the dimming signal S1 output from the dimming signal supply unit 30, and FIG. 5B shows the output voltage Vout of the DC power supply unit 27. FIG. 5C shows the load current IL flowing through the light emitting unit 3.

  First, at timing T <b> 1, the switch 5 is turned off by the user, and a dimming instruction signal S <b> 3 indicating off is output from the switch 5 to the dimming signal supply unit 30 via the control terminal 23. Then, the dimming signal supply unit 30 receives a dimming instruction to turn off the light emitting unit 3, and the dimming signal supply unit 30 gradually decreases the dimming signal S1 so as to gradually reduce the load current IL. And output to the dimming control unit 29.

  Then, the dimming control unit 29 outputs the control signal S21 to the PWM circuit 26 in order to reduce the output voltage Vout of the DC power supply unit 27 according to the dimming signal S1 and to reduce the load current IL. Next, the PWM circuit 26 reduces the on-duty ratio of the transistor Tr1 according to the control signal S21, and as a result, the output voltage Vout decreases. As a result, the load current IL decreases according to the control signal S21. Decreases.

  Next, at timing T2, when the dimming signal S1 reaches the signal level Lmin indicating the minimum output current Imin, the output voltage Vout of the DC power supply unit 27 is set to the set voltage V1 according to the control signal S21 from the dimming control unit 29. Set to Further, after timing T2, the dimming control unit 29 outputs a control signal S22 to the DC voltage source E1 to reduce the load current IL according to the dimming signal S1, and the output current of the constant current circuit 28 is reduced. As a result, the load current IL is reduced according to the dimming signal S1. At timing T3, the load current IL becomes zero, the light emitting unit 3 is turned off, and the output voltage Vout of the DC power supply unit 27 is set to zero according to the control signal S21 from the dimming control unit 29.

  FIG. 6 is an explanatory diagram for explaining an operation when the light emitting unit 3 is turned on in the lighting fixture 1a. 6A shows the dimming instruction signal S3 output from the switch 5 and the dimming signal S1 output from the dimming signal supply unit 30, and FIG. 6B shows the output voltage Vout of the DC power supply unit 27. FIG. 6C shows the load current IL flowing through the light emitting unit 3.

  First, at timing T4, the switch 5 is turned on by the user, and the dimming instruction signal S3 indicating on is output from the switch 5 to the dimming signal supply unit 30 via the control terminal 23. Then, the dimming signal supply unit 30 receives a dimming instruction to turn on the light emitting unit 3, and the dimming signal supply unit 30 gradually increases the dimming signal S1 so as to gradually increase the load current IL. And output to the dimming control unit 29.

  When the dimming signal S1 output from the dimming signal supply unit 30 shifts from the extinguished state to a slightly lit state, the output voltage of the DC power supply unit 27 in accordance with the control signal S21 from the dimming control unit 29 Vout is set to the set voltage V1. Next, when the dimming signal S1 gradually rises, the dimming control unit 29 outputs a control signal S22 to the DC voltage source E1 to increase the load current IL in accordance with the dimming signal S1, and the constant current circuit 28 As a result of increasing the output current, the load current IL is increased according to the dimming signal S1.

  Next, at timing T5, when the dimming signal S1 reaches the signal level Lmin indicating the minimum output current Imin, the output voltage Vout of the DC power supply unit 27 is increased according to the control signal S21 from the dimming control unit 29, and the load The current IL increases according to the output voltage Vout, and the light emission luminance of the light emitting unit 3 gradually increases. At timing T6, the output voltage Vout of the DC power supply unit 27 is set to the voltage VF, the load current IL flowing through the light emitting unit 3 is set to the current IF, and the light emitting unit 3 is fully turned on.

  As described above, when the switch 5 is turned off and the light emitting unit 3 is turned off, the load current IL is gradually reduced by the constant current circuit 28 even in the current range where the load current IL is less than the minimum output current Imin of the DC power supply unit 27. Since the light emitting unit 3 is gradually turned off after being reduced, the light emitting unit 3 can be turned on with low brightness and the light emitting unit 3 can be turned off smoothly. When the switch 5 is turned on to light the light emitting unit 3, the load current IL is gradually reduced by the constant current circuit 28 even in a current range where the load current IL is less than the minimum output current Imin of the DC power supply unit 27. Since the light emitting unit 3 is gradually turned on by being increased, the light emitting unit 3 can be lighted with low brightness and the light emitting unit 3 can be smoothly turned on.

  FIG. 16A is a graph showing the relationship between the lamp current and the brightness when the incandescent lamp is turned off. As shown in FIG. 16 (a), in the case of an incandescent lamp, even if an extinguishing signal instructing extinction is input and the lamp current of the incandescent lamp is made zero, the brightness remains until the incandescent lamp filament cools down. The brightness decreases and the lights turn off smoothly.

  FIG. 16B is a graph showing the relationship between the lamp current and the brightness when the light emitting diode (LED) is turned off. As shown in FIG. 16B, in the case of an LED, the luminance changes with the current flowing through the LED. Therefore, when the extinguishing signal is input and the lamp current of the LED is set to zero, the LED is instantly extinguished.

  Therefore, when a turn-off signal is input to the luminaire, it is conceivable that the LED lamp current is gradually reduced to gradually lower the LED brightness to turn off the LED. FIG. 17 is a graph showing the relationship between the lamp current and the brightness when the LED lamp current is gradually decreased using the illumination power supply circuit 102 according to the background art shown in FIG. As shown in FIG. 17, when the lamp current is gradually decreased after the extinction signal is inputted, the lamp current is gradually decreased in the range where the lamp current is equal to or larger than the minimum output current Imin of the illumination power supply circuit 102. However, if the lamp current becomes less than the minimum output current Imin, the illumination power supply circuit 102 cannot control the output current, and the lamp current becomes zero. Is turned off instantaneously and cannot be turned off smoothly like an incandescent lamp.

  Similarly, when the lamp is turned on, if the lamp current is gradually increased using the illumination power supply circuit 102 according to the background art shown in FIG. 15, the current is controlled in a current range less than the minimum output current Imin. As a result, the lamp current increases instantaneously from zero to the minimum output current Imin. However, in the illumination using the incandescent lamp, as shown in FIG. 18A, even when the lamp current instantaneously increases to the minimum output current Imin, the brightness of the incandescent lamp gradually increases as the filament temperature rises. As a result, the lighting is smooth. On the other hand, in the illumination using the LED, as shown in FIG. 18B, when the lamp current instantaneously increases to the minimum output current Imin, the brightness of the LED also instantaneously increases. You can't get it.

  However, the illumination power supply circuit 2a shown in FIG. 4 can gradually decrease and increase the load current IL of the light emitting unit 3 using the LED both when the light is turned off and when the light is turned on. Can be done smoothly.

(Third embodiment)
Next, the lighting fixture 1b using the illumination power supply circuit 2b according to the third embodiment of the present invention will be described. FIG. 7 is a circuit diagram showing an example of the configuration of an illumination power supply circuit 2b according to the third embodiment of the present invention. The illumination power supply circuit 2b shown in FIG. 7 differs from the illumination power supply circuit 2a shown in FIG. 4 in that the illumination power supply circuit 2b includes a PWM circuit 31 and a switching element SW1 instead of the constant current circuit 28.

  The switching element SW1 is connected between the external connection terminal 25 and the other end of the capacitor C2, and is connected in series with the external connection terminals 24 and 25. As the switching element SW1, various switching elements such as a semiconductor switch such as a relay switch or a transistor can be used.

  The PWM circuit 31 is a control circuit that sets the on / off duty ratio of the switching element SW1 in accordance with the control signal S22 from the dimming control unit 29 and adjusts the effective value of the load current IL by the switching element SW1. The PWM circuit 31 adjusts the effective value of the load current IL to an effective value corresponding to the control signal S22 by increasing / decreasing the on-duty ratio of the switching element SW1 according to the increase / decrease of the current value indicated by the control signal S22. In this case, for example, the PWM circuit 31 gradually increases or decreases the time width during which the switching element SW1 is turned on at a period in which the eye does not feel flickering, for example, at a frequency of about 50 Hz or more, so that the on duty ratio of the switching element SW1 Increase or decrease.

  Since the other configuration is the same as that of the lighting fixture 1a shown in FIG. 4, the description thereof will be omitted, and the operation of this embodiment will be described below. FIG. 8 is an explanatory diagram for explaining an operation when the light emitting unit 3 is turned off in the lighting fixture 1b. 8A shows the dimming instruction signal S3 output from the switch 5 and the dimming signal S1 output from the dimming signal supply unit 30, and FIG. 8B shows the output voltage Vout of the DC power supply unit 27. FIG. 8C shows the load current IL flowing through the light emitting unit 3.

  First, at timing T <b> 1, the switch 5 is turned off by the user, and a dimming instruction signal S <b> 3 indicating off is output from the switch 5 to the dimming signal supply unit 30 via the control terminal 23. Then, the dimming signal supply unit 30 receives a dimming instruction to turn off the light emitting unit 3, and the dimming signal supply unit 30 gradually decreases the dimming signal S1 so as to gradually reduce the load current IL. And output to the dimming control unit 29.

  Then, the dimming control unit 29 outputs the control signal S21 to the PWM circuit 26 in order to reduce the output voltage Vout of the DC power supply unit 27 according to the dimming signal S1 and to reduce the load current IL. Next, the PWM circuit 26 reduces the on-duty ratio of the transistor Tr1 according to the control signal S21, and as a result, the output voltage Vout decreases. As a result, the load current IL decreases according to the control signal S21. Decreases.

  Next, at timing T2, when the dimming signal S1 reaches the signal level Lmin indicating the minimum output current Imin, the output voltage Vout of the DC power supply unit 27 is set to the set voltage V1 according to the control signal S21 from the dimming control unit 29. Set to Further, after timing T2, the dimming control unit 29 outputs a control signal S22 to the PWM circuit 31 so as to gradually decrease the effective value of the load current IL in accordance with the dimming signal S1.

  Next, as shown in FIG. 8C, the PWM circuit 31 gradually decreases the on-duty ratio of the switching element SW1 in accordance with the decrease in the current value indicated by the control signal S22, thereby turning on the load current IL. The duty ratio is gradually reduced. Then, as indicated by the broken line in FIG. 8C, the effective value of the load current IL is gradually decreased and the light emission luminance of the light emitting unit 3 is gradually decreased in a current range that is less than the minimum output current Imin. At timing T3, the effective value of the load current IL becomes zero, the light emitting unit 3 is turned off, and the output voltage Vout of the DC power supply unit 27 is set to zero according to the control signal S21 from the dimming control unit 29.

  Further, when the switch 5 is turned on and the light emitting unit 3 is turned on, the current output is less than the minimum output current Imin in response to the control signal S22 from the dimming control unit 29, contrary to the above-described operation. The PWM circuit 31 gradually increases the on-duty ratio of the switching element SW1, so that the on-duty ratio of the load current IL is gradually increased and the luminance of the light emitting unit 3 is gradually increased.

  As described above, when the switch 5 is turned off and the light emitting unit 3 is turned off, the on-duty ratio of the load current IL is gradually decreased even in the current range where the load current IL is less than the minimum output current Imin of the DC power supply unit 27. As a result, the effective value of the load current IL is gradually reduced and the light emitting unit 3 is gradually turned off, so that the light emitting unit 3 can be turned on with low brightness and the light emitting unit 3 can be turned off smoothly. When the switch 5 is turned on and the light emitting unit 3 is turned on, the on-duty ratio of the load current IL is gradually increased even in a current range where the load current IL is less than the minimum output current Imin of the DC power supply unit 27. Thus, since the effective value of the load current IL is gradually increased and the light emitting unit 3 is gradually turned on, the light emitting unit 3 can be turned on with low brightness and the light emitting unit 3 can be turned on smoothly. .

  By the way, when a plurality of light emitting diodes emit light with a direct current, when the load current IL falls below a certain current value I2, as shown in FIG. 9, variations in light emission luminance due to variations in characteristics of the respective light emitting diodes are easily noticeable. There is an inconvenience of becoming. However, in the luminaire 1b shown in FIG. 7, even if the effective value of the load current IL is lower than the current value I2 as shown by the wavy line in FIG. 8C, it is shown by the solid line in FIG. 8C. Thus, the peak value of the load current IL is larger than the current value I2. For this reason, the high luminance component emitted with a load current larger than the current value I2 remains as a sensation and is felt as an effective value to the human eye.

  In addition, as the lighting fixture 1 shown in FIG. 1, the brightness of the light emission part 3 is adjusted according to the light control signal S1 output from the light controller 4, without the light control signal supply part 30 being provided. Also good.

(Fourth embodiment)
Next, the lighting fixture 1c using the illumination power supply circuit 2c according to the fourth embodiment of the present invention will be described. FIG. 10 is a circuit diagram showing an example of the configuration of an illumination power supply circuit 2c according to the fourth embodiment of the present invention. In the illumination power supply circuit 2c shown in FIG. 10 and the illumination power supply circuit 2a shown in FIG. 4, the illumination power supply circuit 2c is connected between the external connection terminals 24 and 25 in place of the constant current circuit 28. The difference is that 32 is provided. A resistor R1 is connected between the external connection terminal 25 and the other end of the capacitor C2.

  Then, when the dimming signal S1 indicates a current value that is less than the minimum output current Imin, the dimming control unit 29a outputs a control signal S23 to the PWM circuit 26, and outputs to the DC power supply unit 27, for example, the minimum output current Imin. The on / off duty ratio of the transistor Tr1 is set to perform a constant current output operation for outputting an equal constant current I1. Thus, when the load current IL indicated by the dimming signal S1 becomes equal to or less than the minimum output current Imin, the output current Iout of the DC power supply unit 27 is set to a constant current I1.

  Further, the dimming control unit 29a outputs a control signal S24 to the constant current circuit 32, and decreases the current flowing through the constant current circuit 32 in accordance with the increase / decrease of the current value indicated by the dimming signal S1. The load current IL flowing through the light emitting unit 3 connected in parallel with the current circuit 32 is increased or decreased, and the load current IL is set to a current value corresponding to the dimming signal S1.

  Since the other configuration is the same as that of the lighting fixture 1a shown in FIG. 4, the description thereof will be omitted, and the operation of this embodiment will be described below. FIG. 11 is an explanatory diagram for explaining an operation when the light emitting unit 3 is turned off in the lighting fixture 1c. 11A shows the dimming instruction signal S3 output from the switch 5 and the dimming signal S1 output from the dimming signal supply unit 30, and FIG. 11B shows the output current Iout of the DC power supply unit 27. FIG. 11C shows the load current IL flowing through the light emitting unit 3.

  First, at timing T <b> 1, the switch 5 is turned off by the user, and a dimming instruction signal S <b> 3 indicating off is output from the switch 5 to the dimming signal supply unit 30 via the control terminal 23. Then, the dimming signal supply unit 30 receives a dimming instruction to turn off the light emitting unit 3, and the dimming signal supply unit 30 gradually decreases the dimming signal S1 so as to gradually reduce the load current IL. And output to the dimming control unit 29a.

  Then, the dimming control unit 29a outputs the control signal S23 to the PWM circuit 26 in order to reduce the output current Iout of the DC power supply unit 27 according to the dimming signal S1 and to reduce the load current IL. Next, the PWM circuit 26 reduces the on-duty ratio of the transistor Tr1 in response to the control signal S21, and as a result, the output current Iout decreases. As a result, the load current IL decreases in response to the control signal S23. Decreases.

  Next, when the dimming signal S1 becomes a signal level Lmin indicating the minimum output current Imin at timing T2, the output current Iout of the DC power supply unit 27 is a constant current according to the control signal S23 from the dimming control unit 29a. Set to I1. Further, after timing T2, the dimming control unit 29a outputs a control signal S24 to the constant current circuit 32 to decrease the load current IL in accordance with the dimming signal S1, and the output current of the constant current circuit 32 is increased. As a result, the load current IL flowing through the light emitting unit 3 connected in parallel with the constant current circuit 32 decreases, and the load current IL is set to a current value corresponding to the dimming signal S1. At timing T3, the load current IL becomes zero, the light emitting unit 3 is turned off, and the output current Iout of the DC power supply unit 27 is set to zero according to the control signal S23 from the dimming control unit 29a.

  Further, when the switch 5 is turned on and the light emitting unit 3 is turned on, the current output range is less than the minimum output current Imin in response to the control signal S24 from the dimming control unit 29a. As the current flowing through the constant current circuit 32 is gradually reduced, the load current IL is gradually increased, and the luminance of the light emitting unit 3 is gradually increased.

  As described above, when the switch 5 is turned off and the light emitting unit 3 is turned off, the load current IL is gradually reduced by the constant current circuit 32 even in a current range where the load current IL is less than the minimum output current Imin of the DC power supply unit 27. Since the light emitting unit 3 is gradually turned off after being reduced, the light emitting unit 3 can be turned on with low brightness and the light emitting unit 3 can be turned off smoothly. When the switch 5 is turned on and the light emitting unit 3 is lit, the effective value of the load current IL is obtained by the constant current circuit 32 even in a current range where the load current IL is less than the minimum output current Imin of the DC power supply unit 27. Is gradually increased and the light emitting unit 3 is gradually turned on, so that the light emitting unit 3 can be turned on with low brightness and the light emitting unit 3 can be turned on smoothly.

  In addition, as the lighting fixture 1 shown in FIG. 1, the brightness of the light emission part 3 is adjusted according to the light control signal S1 output from the light controller 4, without the light control signal supply part 30 being provided. Also good.

  Further, a variable resistor VR1 may be used instead of the constant current circuit 32 as in the illumination power supply circuit 2d shown in FIG. In this case, the dimming control unit 29b outputs the control signal S25 to the variable resistor VR1, and is variable by increasing or decreasing the resistance value of the variable resistor VR1 according to the increase or decrease of the current value indicated by the dimming signal S1. The current flowing through the resistor VR1 is decreased, the load current IL flowing through the light emitting unit 3 connected in parallel with the variable resistor VR1 is increased or decreased, and the load current IL is set to a current value corresponding to the dimming signal S1.

  As a result, the lighting fixture 1d shown in FIG. 12 can turn on the light emitting unit 3 with low brightness as well as the lighting fixture 1c shown in FIG. 10, and smoothly changes the brightness when the light emitting unit 3 is turned off and turned on. Can be.

(Fifth embodiment)
Next, a lighting fixture 1e using the lighting power supply circuit 2e according to the fifth embodiment of the present invention will be described. FIG. 13 is a circuit diagram showing an example of the configuration of an illumination power supply circuit 2e according to the fifth embodiment of the present invention. The illumination power supply circuit 2e shown in FIG. 13 is different from the illumination power supply circuit 2a shown in FIG. 4 in the following points. That is, the illumination power supply circuit 2e does not include the constant current circuit 28 and the dimming signal supply unit 30, and the dimming instruction signal S3 that is an on / off signal of the switch 5 is a dimming instruction to turn off the light emitting unit 3. The control terminal 23 accepts the dimming instruction to light the light emitting unit 3 and the dimming control unit 29b receives the dimming instruction.

  The DC power supply unit 27e does not include the capacitor C2, one end of the secondary winding n2 of the transformer T is connected to the anode of the diode D1, and the cathode of the diode D1 is connected to the external connection terminal 24 via the switch SW2. The capacitor C2 is connected between the external connection terminal 24 and the other end of the secondary winding n2. As the switch SW2, various switching elements such as a relay switch and a semiconductor switch such as a transistor can be used.

  Other configurations and operations are the same as those of the lighting fixture 1a shown in FIG. 4 except that the operation of the dimming control unit 29b is different as will be described later, and the description thereof will be omitted. Hereinafter, the operation of the present embodiment will be described. To do. First, when the switch 5 is turned on by the user and a dimming instruction for turning on the light emitting unit 3 is received by the dimming control unit 29b, the switch SW2 is turned on according to the control signal S24 from the dimming control unit 29b. In addition, the output voltage Vout of the DC power supply unit 27e is set to the voltage VF in accordance with the control signal S21 from the dimming control unit 29b, the load current IL flowing through the light emitting unit 3 is set to the current IF, and the light emitting unit 3 All lights are turned on. Then, the capacitor C2 is charged with the voltage VF.

  Next, when the switch 5 is turned off by the user and a dimming instruction for turning off the light emitting unit 3 is received by the dimming control unit 29b, the switch SW2 is switched according to the control signal S24 from the dimming control unit 29b. The current supply from the direct current power supply unit 27e to the light emitting unit 3 is cut off, and the direct current power supply unit 27e is disconnected from the capacitor C2. Then, since the capacitor C2 is charged to the voltage VF, when the capacitor C2 is discharged, the load current IL flows, the light emission unit 3 continues to emit light, the capacitor C2 is discharged, and the charging voltage gradually decreases. As a result, the load current IL is gradually decreased, and the light emission luminance of the light emitting unit 3 is gradually decreased.

  Thereby, since the lighting fixture 1e can reduce load current IL gradually at the time of light extinction of the light emission part 3 using LED, it can perform light extinction of the light emission part 3 smoothly. Further, since the constant current circuit 28 and the dimming signal supply unit 30 are not used, the circuit can be simplified.

  For example, as shown in FIG. 14, the dimming control unit 29 b receives a dimming signal for turning off the light emitting unit 3, and then gradually decreases the output voltage Vout of the DC power supply unit 27 e to reduce the load current IL. After the load current IL reaches the minimum output current Imin, the switch SW2 is turned off to cause the light emitting unit 3 to emit light by the discharge current of the capacitor C2, and the light emission luminance of the light emitting unit 3 gradually decreases. You may make it make it. In this case, the load current IL is decreased to the minimum output current Imin to gradually decrease the light emission luminance of the light emitting unit 3, and then the light emission luminance of the light emitting unit 3 is reduced using the decrease in the load current IL due to the discharge of the capacitor C2. Since it is gradually reduced, the smoothness of the extinguishing can be improved.

It is a circuit diagram for demonstrating an example of the structure of the lighting fixture using the power supply circuit for illumination which concerns on the 1st Embodiment of this invention. It is explanatory drawing for demonstrating operation | movement in the case of making the light emission part light-extinguish gradually in the lighting fixture shown in FIG. It is explanatory drawing for demonstrating operation | movement in the case of making a light emission part light up gradually in the lighting fixture shown in FIG. It is a circuit diagram which shows an example of a structure of the lighting fixture using the power supply circuit for illumination which concerns on the 2nd Embodiment of this invention. It is explanatory drawing for demonstrating operation | movement in the case of making a light emission part light-extinguish in the lighting fixture shown in FIG. (A) shows the dimming instruction signal output from the switch and the dimming signal output from the dimming signal supply unit, (b) shows the output voltage of the DC power supply unit, and (c) flows through the light emitting unit. The load current is shown. It is explanatory drawing for demonstrating operation | movement in the case of making a light emission part light in the lighting fixture shown in FIG. (A) shows the dimming instruction signal output from the switch and the dimming signal output from the dimming signal supply unit, (b) shows the output voltage of the DC power supply unit, and (c) flows through the light emitting unit. The load current is shown. It is a circuit diagram which shows an example of a structure of the lighting fixture using the power supply circuit for illumination which concerns on the 3rd Embodiment of this invention. It is explanatory drawing for demonstrating operation | movement in the case of making a light emission part light-extinguish in the lighting fixture shown in FIG. It is explanatory drawing for demonstrating the brightness variation of a light emitting diode. It is a circuit diagram which shows an example of a structure of the lighting fixture using the power supply circuit for illumination which concerns on the 4th Embodiment of this invention. It is explanatory drawing for demonstrating operation | movement in the case of making a light emission part light-extinguish in the lighting fixture shown in FIG. (A) shows the dimming instruction signal output from the switch and the dimming signal output from the dimming signal supply unit, (b) shows the output current of the DC power supply unit, and (c) flows through the light emitting unit. The load current is shown. It is a circuit diagram which shows the modification of the lighting fixture shown in FIG. It is a circuit diagram which shows an example of a structure of the lighting fixture using the power supply circuit for illumination which concerns on the 5th Embodiment of this invention. It is explanatory drawing which shows an example of operation | movement of the lighting fixture shown in FIG. It is a block diagram which shows the structure of the power supply circuit for illumination which concerns on background art, and a lighting fixture using the same. (A) is a graph which shows the relationship between the lamp electric current at the time of turning off an incandescent lamp, and a brightness | luminance. (B) is a graph showing the relationship between the lamp current and the brightness when the light emitting diode is turned off. It is a graph which shows the relationship between the lamp current at the time of reducing the lamp current of LED gradually using the power supply circuit for illumination shown in FIG. 15, and a brightness | luminance. It is a graph which shows the luminance change at the time of lighting of an incandescent lamp and LED.

Explanation of symbols

1, 1a, 1b, 1c, 1d, 1e Lighting fixtures 2, 2a, 2b, 2c, 2d, 2e Lighting power circuit 3 Light-emitting unit 4 Dimmer 5 Switch 21, 22 Power connection terminal 23 Control terminal 24, 25 External Connection terminal 26, 31 PWM circuit 27, 27e DC power supply unit 28, 32 Constant current circuit 29, 29a, 29b Dimming control unit 30 Dimming signal supply unit C1, C2 capacitor IL load current SW1 switching element SW2 switch T transformer Tr1 transistor Tr2 transistor VR1 variable resistor

Claims (9)

First and second connection terminals for connecting a light emitting unit using a light emitting diode;
A dimming signal supply unit that receives a dimming instruction for instructing the brightness of the light emitting unit and supplies a dimming signal indicating a load current to flow between the first and second connection terminals according to the dimming instruction When,
A direct current power supply unit for outputting power for light emission to the light emitting unit;
A current adjusting unit that adjusts a load current flowing between the first and second connection terminals based on the DC power output from the DC power supply unit;
When the dimming signal supplied from the dimming signal supply unit indicates a current value that exceeds a preset current value, the DC power corresponding to the dimming signal is supplied to the first and second DC power supply units. Dimming that is output between the connecting terminals and that adjusts the load current to a current value corresponding to the dimming signal by the current adjusting unit when the dimming signal indicates a current value less than the set current value. A lighting power supply circuit comprising: a control unit. The said light control signal supply part changes the said light control signal so that the said load current may be decreased gradually, when the light control instruction | indication which turns off the said light emission part is received. Power supply circuit for lighting. The said light control signal supply part changes the said light control signal so that the said load current may be increased gradually, when the light control instruction | indication which lights the said light emission part is received. Power supply circuit for lighting. The current adjustment unit is a constant current circuit connected in series with the first and second connection terminals,
When the dimming signal indicates a current value less than the set current value, the dimming control unit is preset by the DC power supply unit into a series circuit of the first and second connection terminals and the constant current circuit. The illumination power supply circuit according to claim 1, wherein the set voltage is output and a load current corresponding to the dimming signal is caused to flow by the constant current circuit. The current adjusting unit is a switching element connected in series with the first and second connection terminals,
When the dimming signal indicates a current value less than the set current value, the dimming control unit is preset by the DC power supply unit into a series circuit of the first and second connection terminals and the switching element. The on-off duty ratio of the said switching element is increased / decreased according to the increase / decrease in the electric current value shown by the said light control signal while outputting the set voltage which was set forth. Power supply circuit. The current adjustment unit is a constant current circuit connected between the first and second connection terminals,
The dimming control unit outputs a constant current preset between the first and second connection terminals by the DC power source unit when the dimming signal indicates a current value less than the set current value. The illumination power supply circuit according to claim 1, wherein the current flowing through the constant current circuit is decreased according to an increase or decrease in a current value indicated by the dimming signal. The current adjusting unit is a variable resistor connected between the first and second connection terminals,
The dimming control unit outputs a constant current preset between the first and second connection terminals by the DC power source unit when the dimming signal indicates a current value less than the set current value. The power supply circuit for illumination according to any one of claims 1 to 3, wherein the resistance value of the variable resistor is increased or decreased according to an increase or decrease in the current value indicated by the dimming signal. The current regulator is
A capacitor connected between the first and second connection terminals and charged by an output voltage of the DC power supply unit;
A switching element for disconnecting the capacitor from the DC power supply unit,
The dimming control unit causes the switching element to disconnect the capacitor from the DC power supply unit when a dimming instruction for turning off the light emitting unit is received by the dimming instruction receiving unit. The power supply circuit for illumination according to claim 1. The power supply circuit for illumination according to any one of claims 1 to 8,
And a light-emitting unit connected between the first and second connection terminals.

Images