JP2011249124A - Overcurrent prevention type power unit and luminaire using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an overcurrent prevention type power unit that prevents an illumination load from being stressed owing to an overcurrent generated after a constant voltage unit starts supplying a voltage.SOLUTION: An overcurrent prevention type power unit 1 which prevents an overcurrent from flowing to an illumination load 4 comprises: a constant voltage unit 2 which supplies a constant voltage; a constant current unit 2 which operates by receiving a voltage from the constant voltage unit 2 to drive a luminaire; a current detection portion 6 which detects a value of a current supplied to the constant current unit 3 after the constant voltage unit 2 starts supplying the voltage; and a light control portion 2a which controls an output current of the constant current unit 3. The light control portion 2a receives a detection result of the current value by the current detection portion 6 and controls the output current from the constant current unit 3. Consequently, an overcurrent flowing to the illumination load 4 is suppressed at the startup of the luminaire 5 to prevent the illumination load 4 from being stressed.

Description

  The present invention relates to an overcurrent-preventing power supply apparatus that prevents an overcurrent from flowing through an illumination load that uses an organic EL (Electro Luminescence) or a light emitting diode (LED), and a lighting fixture using the same.

  An example of a conventional lighting fixture using this type of power supply device is shown in FIG. The luminaire 80 includes a voltage supply unit B that receives supply from the power supply unit A and supplies a constant voltage to the load C, a load C such as a lamp that receives voltage from the voltage supply unit B, and an output of the voltage supply unit B. Is provided with a control circuit unit D that controls to be constant. The voltage supply unit B in such a lighting fixture 80 gradually increases in voltage value from the initial voltage to a specified voltage after the voltage supply is started.

However, since the lighting fixture 80 performs constant power control on the load C, the output supplied from the voltage supply unit B to the load C at an early timing before the output of the voltage supply unit B becomes a steady voltage. There is a problem that the current reaches an overcurrent (surge current) and stress such as a voltage trip abnormality occurs in the load C. For example, in the voltage-current characteristic of the lighting load as shown in FIG. 9, in the case of the operation shown by the curve 90, an overcurrent I _peak is generated in the load current when the voltage V1 is applied to the lighting load, and the lighting load is stressed. Is given.

  A lighting fixture 100 as shown in FIG. 10 that addresses this problem is known (see, for example, Patent Document 1). In addition to the same configuration as the above-described lighting fixture 80, the lighting fixture 100 has an output voltage that is higher than the actual output value for the multiplier 102 used in the constant power control unit when the output voltage of the voltage supply unit B is low. A configuration in which a high voltage value is input to the multiplier 102 from another power source 101 is provided. By setting it as such a structure, the lighting fixture 100 prevents generation | occurrence | production of an overcurrent by making the output current small when the output voltage of the voltage supply unit B is low.

Japanese Patent Laid-Open No. 10-335086

  However, in the circuit configuration of the luminaire 100 as shown in FIG. 10 above, (1) because of feedback control, the detection value may diverge due to errors and noise, and (2) constant power control is performed. Therefore, there is a problem that a circuit configuration of the multiplier 102 that multiplies the voltage value and the current value is required.

  Furthermore, in general, there is a method of outputting the current of the constant current unit after the output voltage of the constant voltage unit has risen sufficiently. In this method, power is supplied from the power supply to the lighting load. However, there is a problem that a longer period is required until the lighting is delayed and the lamp is turned on.

  The present invention has been made in view of the above problems, and in an overcurrent prevention type power supply device that lights a lighting load by supplying a current from a constant current unit driven by receiving a voltage from a constant voltage unit, the constant voltage It is an object of the present invention to provide an overcurrent-preventing power supply apparatus and a lighting fixture that prevent an overcurrent from flowing through a lighting load due to an increase in current value after voltage supply is started by a unit, and a lighting fixture.

  In order to achieve the above object, an overcurrent prevention type power supply device according to the present invention is an overcurrent prevention type power supply device for preventing an overcurrent to a lighting load. A constant voltage unit for supplying a constant voltage; A constant current unit that operates in response to the voltage of the current, drives a lighting load, a current detection unit that detects a current value supplied to the constant current unit after the voltage supply by the constant voltage unit is started, and the constant current unit A dimming unit for controlling an output current, and the dimming unit receives the detection result of the current value in the current detection unit and controls the output current from the constant current unit.

  In this overcurrent prevention type power supply device, the constant current unit is connected to a lighting load that is a light emitting diode or an organic EL, and a voltage at the time of rising of the current of the lighting load is an input at the start of current output of the constant current unit. Preferably it is higher than the voltage.

  In the overcurrent prevention type power supply device, it is preferable that the dimmer unit cancels the control of the output current from the constant current unit after the current value detected by the current detector unit becomes a constant value. .

  The lighting fixture of the present invention includes the above-described overcurrent-preventing power supply device, a lighting load, and a connection portion that connects the power supply device and the lighting load.

  According to the overcurrent prevention type power supply device of the present invention, after the voltage supply by the constant voltage unit is started, the current value flowing through the constant current unit is detected, and based on this current value, the dimming unit detects the lighting load from the constant current unit. Since the current flowing to the lighting load is controlled, the supply of overcurrent from the constant current unit to the lighting load is suppressed at the time of startup, and the occurrence of stress on the lighting load can be reduced.

The block diagram of the lighting fixture using the overcurrent prevention type power supply device which concerns on embodiment of this invention. The circuit diagram of the constant voltage unit in the apparatus of the embodiment. The circuit diagram of the constant current unit in the apparatus of the embodiment. The voltage-current characteristic view of the illumination load for demonstrating operation | movement of the power supply device which concerns on the embodiment. (A) The figure which shows the output voltage waveform of an identification voltage unit, (b) The figure which shows the output current waveform of an identification current unit. The block diagram of the lighting fixture using the power supply device which concerns on the embodiment. (A) The perspective view of the lighting fixture, (b) The perspective view from the lower side of the lighting fixture. The circuit diagram of the conventional power supply device. The voltage-current characteristic view of the illumination load for demonstrating operation | movement of the conventional power supply device. Another circuit diagram of the conventional power supply device.

  An overcurrent prevention type power supply apparatus according to an embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, an overcurrent prevention type power supply device 1 (hereinafter referred to as a power supply device) of this embodiment includes a constant voltage unit 2 that is supplied with power from an AC power supply (AC) and outputs a constant voltage, and a constant voltage unit. And a constant current unit 3 that receives the voltage from 2 and drives the lighting load 4 to turn on. Here, the power supply device 1 and the lighting load 4 constitute a lighting fixture. A lighting fixture in which the constant current unit 3 and the lighting load 4 are integrated into the lamp 5 and the constant voltage unit 2 and the lamp 5 are separated and wired is also possible.

  The current detector 6 detects the input current supplied from the constant voltage unit 2 to the constant current unit 3 after the voltage supply by the constant voltage unit 2 is started, and feeds it back to the dimmer 2a. The dimmer 2 a receives the detection result of the current value at the start of the operation of the current detector 6 and transmits a dimmer signal to the constant current unit 3. The dimming signal changes in response to the detection result by the current detection unit 6. For example, the dimming unit 2 a performs dimming of the constant current unit 3 after the current value detected by the current detection unit 6 becomes constant. Release control. The dimming signal from the dimming unit 2a can be reduced in wiring by transmitting it to the constant current unit 3 side via the power supply line of the constant voltage unit 2.

  The illumination load 4 is a light emitting diode such as an organic EL light emitting element or an LED, and is composed of a light emitting element that receives light from the constant current unit 3 connected via a connector and emits light. The illumination load 4 uses an organic EL light emitting element, but may be any light source that is lit with a direct current, including other solid light emitting elements such as an LED light emitting element.

Hereinafter, the circuit configuration of the constant voltage unit 2 will be described.
As shown in FIG. 2, the constant voltage unit 2 is an AC / DC converter, and includes an input unit (connection unit) 20, a low-pass filter (LPF) 21, a rectifier circuit unit 22, a control power supply circuit 23, and a booster. A chopper part 24 and an output part (connection part) 25 are provided.

  The input unit 20 is connected to an AC power source (AC), and the LPF 21 removes the high-frequency component in order to make the AC voltage from the input unit 20 sine wave. The rectifier circuit unit 22 performs full-wave rectification of the AC voltage from the LPF 21 using a diode bridge (DB). The control power supply circuit 23 connects a series circuit of resistors R4 and R5 to both output terminals of the rectifier circuit unit 22, and connects a Zener diode ZD1 in parallel to the resistor R5 to generate a constant voltage source Vcc to be supplied to the control circuit. For supplying power to the step-up chopper 24 and the like.

  The step-up chopper unit 24 includes a choke coil L1, a switching element Q1 made of an n-channel MOSFET, a diode D1, a drive circuit 26 for driving the switching element Q1, and a constant voltage control unit for controlling the drive circuit 26. 27. A series circuit of a diode D1 and an electric field capacitor C1 is connected in parallel to the series circuit of the switching element Q1 and the resistor R1. Further, both ends of the capacitor C1 are connected in parallel with a series circuit of resistors R2 and R3, and are connected to an output unit 25 having an output connector. The secondary coil L2 coupled to the coil L1 has one end connected to the constant voltage control unit 27 and the other end grounded, and supplies the control voltage supply to the constant voltage control unit 27. The switching element Q1 is driven by an output signal from the drive circuit 26 that is generated based on a control signal from the constant voltage control unit 27.

  The resistors R2 and R3 are detection resistors for detecting the output voltage V. The resistors R2 and R3 divide both ends of the capacitor C1 and use the voltage of the resistor R3 as a detection voltage. A connection point between the resistors R2 and R3 is connected to the constant voltage control unit 27 for feedback control of the output voltage V.

  The constant voltage control unit 27 receives the detection voltage from the resistor R3 as a feedback control signal, and generates a voltage control signal for setting the output voltage V of the capacitor C1 to a desired voltage value Vo based on the detection voltage. The drive circuit 26 and the switching element Q1 are controlled. This voltage control signal is formed by a PWM control signal, and controls the drive circuit 26, and the drive circuit 26 drives the switching element Q1 in pulses with the PWM signal. The output of the switching element Q1 is charged in the capacitor C1, and a DC output voltage V having a constant voltage Vo is obtained. Note that the switching frequency of PWM is several tens KHz to several MHz.

  Further, the constant voltage control unit 27 can use the voltage generated in the resistor R1 to forcibly turn off when the current flowing through the switching element Q1 reaches a predetermined peak value. In addition, the switching element Q1 can be forcibly turned on by detecting the timing when the current becomes zero using the winding voltage of the coil L2.

  The constant voltage unit 2 feeds back the output voltage V to the constant voltage control unit 27, thereby repeatedly turning on and off the switching element Q1 so that the voltage generated in the resistor R3 becomes a desired value. The output voltage V can be set to the constant voltage Vo while improving the distortion.

Next, the circuit configuration of the constant current unit 3 will be described.
As shown in FIG. 3, the constant current unit 3 includes an input unit (connection unit) 30, a control power supply circuit 31, a voltage detection unit 32, a setting unit 33, a DC-DC conversion unit 34, and a constant current control. A unit 35, a current detection unit 36, and an output unit (connection unit) 37.

  The input unit 30 is supplied with the output voltage V from the output unit 25 of the constant voltage unit 2 as the input voltage V to the constant current unit 3. The control power supply circuit 31 has the same configuration as the control power supply circuit 23 of the constant voltage unit 2, and includes a constant current unit such as a setting unit 33, a DC-DC conversion unit 34, a constant current control unit 35, and a current detection unit 36. A constant voltage source Vcc is supplied to each circuit in 3.

  The voltage detection unit 32 includes a series circuit of resistors Ra and Rb connected in parallel to both terminals of the input unit 30, and inputs a voltage detected at the connection point and proportional to the input voltage V to the setting unit 33. The voltage detector 32 detects the input voltage V supplied from the constant voltage unit 2 after the voltage supply by the constant voltage unit 2 is started. Since the voltage detection unit 32 can detect the output voltage of the constant voltage unit 2 in the constant current unit 3, no special wiring is required for voltage detection.

  The setting unit 33 includes a comparator COMP1 for voltage comparison, a logical inverter circuit NOT1 to which the output of COMP1 is input, and an AND circuit AND1 to which the output of NOT1 is input. The setting unit 33 receives the detection voltage from the voltage detection unit 32 and the current control signal from the constant current control unit 35, sets the operation start voltage at which the constant current unit 3 starts to operate, and detects the voltage. The operation start voltage of the constant current unit 3 is changed in response to the detection result by the unit 32. The output of the setting unit 33 is switched based on the comparison between the input voltage V and the operation start voltage, and is supplied as a control signal for the DC-DC conversion unit 34.

  Specifically, COMP1 is a battery in which the detection voltage Vb from the connection point of the resistors Ra and Rb of the voltage detection unit 32 is input to the negative input terminal, and the reference voltage Vref is formed between the positive input terminal and the ground. A series circuit of E and resistor Rd is connected. The output terminal of COMP1 is connected to a connection point between the battery E and the resistor Rd via the resistor Rc. AND1 receives a signal obtained by inverting the output of COMP1 at NOT1 and a current control signal from the constant current control unit 35, and its output is connected to the drive circuit 38 of the DC-DC conversion unit 34.

The setting unit 33 forms a hysteresis circuit as shown below by COMP1, the battery E, the resistor Rc, and the resistor Rd. For example, if a high (H) level (Vcc) is first generated as the output of COMP1, the comparison voltage Va applied to the positive side input terminal of COMP1 is expressed by Equation 1.
Va = Vref + Rd · Vcc / (Rc + Rd) (Equation 1).
Vref is a reference voltage for forming a hysteresis and formed by the battery E, but is not limited thereto.

  Here, the operation of the setting unit 33 will be described. First, when the detection voltage Vb generated at the end of the resistor Rb input to the negative terminal increases and exceeds the comparison voltage Va, the output of COMP1 is switched to the low (L) level (GND). At this time, since the output of COMP1 is switched from the H level to the L level, the voltage generated at the resistor Rd end of the comparison voltage Va of COMP1 disappears, and Va = Vref. Therefore, when the detection voltage Vb on the minus side of COMP1, that is, the voltage at the end of the resistor Rb is decreased, the output of COMP1 is not switched to the H level again unless the detection voltage Vb is smaller than Vref. .

  From this, the operation start voltage when the voltage V from the constant voltage unit 2 decreases, that is, the operation stop voltage of the constant current unit 3 is the constant current unit when the input voltage V from the constant voltage unit 2 increases. 3 is lower than the operation start voltage of 3. Therefore, the operation start voltage and the operation stop voltage of the constant current unit 3 are different, and the operation of the constant voltage unit 2 has a hysteresis characteristic.

  The DC-DC converter 34 includes a drive circuit 38, a switching element Q2 driven by the drive circuit 38, a regenerative diode D2, a choke coil L3, and a capacitor C2. The diode D2 is reversely connected between the output side of the switching element Q2 and the ground, and a series circuit of a choke coil L3 and a capacitor C2 is connected in parallel at both ends thereof. The capacitor C2 is connected in parallel with the series circuit of the lighting load 4 and the current detection resistor R6, the connection point between the lighting load 4 and the resistor R6 is connected to the current detection unit 36, and the other end of the resistor R6 is grounded. ing.

  The DC-DC converter 34 forms a step-down chopper circuit, and converts the input voltage V from the input unit 30 into a voltage required for the illumination load 4 by switching the switching element Q2 at a high frequency by the drive circuit 38. It outputs from the output part 37, and the illumination load 4 is lighted. In the constant current unit 3, the configuration of the setting unit 33 that sets the voltage at the start of operation is not essential, and it is possible to adopt another circuit configuration that becomes a DC voltage converter.

  Next, the voltage / current load in the illumination load 4 of the power supply device 1 according to the present embodiment will be described. A curve 41 shown in FIG. 4 shows a characteristic curve for constant power control of the constant current unit 3 (dim curve on the dim side is darker on the full side and brighter on the full side).

  Generally, when the load voltage V is applied and the rising voltage Vf of the lighting load 4 is exceeded, the lighting load 4 has a voltage-current characteristic in which the load current I begins to flow and the load current I increases as the load voltage V increases. . The rising voltage Vf value is almost determined by the device.

  In the present embodiment, in order to suppress the generation of a surge current when the lighting load 4 rises, the dimming unit 2 a is connected to the lighting load 4 from the constant current unit 3 based on the current value detected by the current detection unit 6. Controls the output current.

  That is, when an input voltage is applied from the constant voltage unit 2 to the constant current unit 3 when the lighting fixture 1 is started up, the dimmer 2a receives the detection result of the current value from the current detector 6, and Based on the value, the current output from the constant current unit 3 to the lighting load 4 is controlled. For example, as shown by the black point P1 in FIG. 4 based on the current value, the dimming unit 2a receives the current I1 (from the constant current unit 3 to the lighting load 4 when reaching the starting voltage Vth (rising voltage Vf + 3V, etc.) Control to apply A) first.

  Then, as shown by the arrow Y1 in FIG. 4, the dimming unit 2a changes the output current from the constant current unit 3 to the illumination load 4 to the state of I1 (A) while the voltage value reaches V1 from Vth. keep. In addition, the dimmer 2a changes the output current to the illumination load 4 along the characteristic of the constant power curve 41 while the voltage value reaches the rated output voltage Vn from V1 as indicated by the arrow Y2. ) Is gradually reduced to I0 (A) indicated by black point P2. After reaching the rated output voltage Vn, the dimming unit 2a ends the control of the output current from the constant current unit 3 to the lighting load 4.

  When the constant current unit 3 is supplied with an overcurrent, the constant voltage unit 2 often starts up after the power is turned on. That is, in the process in which the output voltage from the constant voltage unit 2 gradually increases, the maximum current is reached when the constant current unit 3 reaches the current rising voltage of the lighting load 4 after the current output supply to the lighting load 4 is started. And the stress of the constant voltage unit 2 is the largest. In the power supply device 1 of the present embodiment, the current rising voltage of the lighting load 4 is higher than the input voltage Vth at the start of current output of the constant current unit 3, and the stress generated in the constant voltage unit 2 can be alleviated. .

As shown in FIG. 5A, the output voltage V at the capacitor C1 end of the constant voltage unit 2 becomes the rated output voltage Vn while gradually increasing from the output start voltage Vf. The output voltage V reaches the starting voltage Vth of the constant current unit 3 at time t1. Further, as shown in FIG. 5B, the current I flowing through the coil L3 reaches the rising current I1 at the time t1 of the starting voltage Vth, and the dimmer 2a causes the overcurrent value I _peak from the constant current unit 3 to be _increased . Generation is suppressed, and the rated output current Io is maintained after time t3.

  As described above, the dimming unit 2a performs dimming control on the lighting load 4 at the time of startup, and the constant current unit 3 outputs a current to the lighting load 4 from the time (t1) when the startup voltage Vth is reached. For this reason, the power supply device 1 gives the current rising voltage to the lighting load 4 more quickly than the dimming control that outputs the current to the lighting load 4 after the time when the rated output voltage Vn is reached (t3). Thus, the lighting load 4 can be quickly turned on.

  As described above, according to the power supply device 1 according to the present embodiment, the current detection unit 6 detects and adjusts the output current value from the constant voltage unit 2 to the constant current unit 3 after the voltage application is started. Feedback to the optical unit 2a. Then, the dimmer 2a controls the output current from the constant current unit 3 to the lighting load 4 based on the detected current value and exceeds the predetermined current value, so that an overcurrent is generated in the lighting load 4. To prevent stress.

  Further, since the power supply device 1 is controlled using the dimmer 2a, the constant current unit 3 can be started up before the output voltage V from the constant voltage unit 2 reaches the rated voltage Vn. While suppressing overcurrent, the rise of the whole power supply device 1 can be accelerated and the illumination load 4 can be lighted quickly.

  Furthermore, since the output current from the constant current unit 3 to the lighting load 4 is limited to the current range of the dimming signal from the dimming unit 2a, an overcurrent occurs in the lighting load 4 due to feedback divergence or the like. Can be prevented. Furthermore, since feedback control using the current detection unit 6 and the light control unit 2a is performed, the power supply device 1 does not require a complicated multiplier circuit configuration for multiplying the voltage value and the current value.

Hereinafter, the lighting fixture using the power supply device 1 according to the present embodiment will be described.
The lighting fixture shown in FIG. 6 includes the constant voltage unit 2 (overcurrent prevention type power supply device), a plurality of lamps (lighting loads) 5 (5a, 5b) fed by the constant voltage unit 2, and the constant voltage unit 2 And a connecting portion 51 for connecting the lamp 5. The lamp 5 has a light emitting element (illumination load) 4a, a constant current unit 3, and a dimming signal receiving unit 9 together with the connection unit 51, and the constant voltage unit 2 is connected via the connection unit 51 made of a connector or the like. It is connected to the output unit by wiring. In the constant voltage unit 2, the output voltage V from the output unit and the dimming signal S are connected to the lamp 5 with a common ground line, and are connected to the constant current unit 3 and the dimming signal receiving unit 9 in the lamp 5, respectively. Supplied.

  The light emitting element 4a is composed of one or a plurality of solid state light emitting elements such as an organic EL or LED in which the input current and the light output are in a substantially proportional relationship. The dimming signal receiving unit 9 receives the dimming signal S from the dimming signal transmission unit 7 of the constant voltage unit 2, restores the original dimming command value, and transmits it to the constant current unit 3. The constant current unit 3 has a dimming function and receives a command value from the dimming signal receiving unit 9 to perform PWM dimming and amplitude dimming of the light emitting element 4a. The dimming signal receiver 9 may be provided in the constant current unit 3.

  Even when a plurality of lamps 5 are connected to the constant voltage unit 2, this lighting fixture can suppress the peak current from the constant voltage unit 2 flowing through the wiring at the start of operation. As a result, it is possible to reduce stress on the circuit elements of the lamp 5 due to overcurrent, and after the lighting operation, stable illumination that is resistant to power supply fluctuations can be obtained. Further, the distance between the lamp 5 and the constant voltage unit 2 can be adjusted to an arbitrary length by the wiring between the constant voltage unit 2 and each connection portion 51. Moreover, since the light emitting element 4a of LED or an organic EL element was used, a planar thin luminaire can be obtained.

  Fig.7 (a) shows the example at the time of comprising a lighting fixture with a some module. This lighting fixture includes a power supply unit 1a obtained by modularizing the constant voltage unit 2 and the constant current unit 3, and a load module 4b obtained by modularizing a plurality of light emitting elements 4a. Due to these modularizations, the lighting fixture can be made compact, and replacement and repair can be facilitated. FIG. 7B is an external view of a lighting fixture including the power supply device 1, which receives power from the power supply device 1 and emits light from the organic EL panel side which is a light emitting surface.

  In addition, this invention is not restricted to the structure of the said embodiment, A various deformation | transformation is possible in the range which does not change the meaning of invention. For example, in each of the above embodiments, the switching element is not limited to the FET, and other semiconductor elements such as a bipolar transistor may be used. Further, when a plurality of lighting loads 4 are connected to one power supply device 1, the lighting loads 4 may be connected in series, in parallel, or a combination thereof. Further, the power supply 1 may be a battery as well as an AC power supply. Furthermore, although a resistor is used for current detection, a transformer or the like may be used.

1 Power supply (overcurrent prevention power supply, lighting equipment)
2 constant voltage unit 2a light control unit 3 constant current unit 32 voltage detection unit 33 setting unit 4 lighting load 4a light emitting element (lighting load, lighting fixture)
5, 5a, 5b Lamp (lighting fixture)
6 Current detection part 51 Connection part (lighting fixture)
Vth start voltage

Claims (4)

In the overcurrent prevention power supply that prevents overcurrent to the lighting load,
A constant voltage unit for supplying a constant voltage;
A constant current unit that operates by receiving a voltage from the constant voltage unit and drives a lighting load;
A current detector for detecting a current value supplied to the constant current unit after voltage supply is started by the constant voltage unit;
A light control unit for controlling the output current of the constant current unit,
The dimming unit receives the detection result of the current value in the current detection unit, and controls the output current from the constant current unit. The constant current unit is connected to a lighting load that is a light emitting diode or an organic EL,
The overcurrent-preventing power supply apparatus according to claim 1, wherein a voltage at the time of current rising of the lighting load is higher than an input voltage at the start of current output of the constant current unit.   The said light control part cancels | releases control of the output current from the said constant current unit, after the electric current value detected in the said electric current detection part becomes a fixed value. The overcurrent prevention type power supply device described.   The overcurrent prevention type power supply device according to any one of claims 1 to 3, an illumination load, and a connection portion that connects the power supply device and the illumination load. Instruments.

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