JP5720457B2 - Lighting control circuit and lighting device - Google Patents

Description

  The present invention relates to a technology for lighting a light emitting diode (hereinafter referred to as LED) or an organic EL.

As a conventional technique, a so-called fade-in lighting technique is known in which LED is gradually brightened when power is turned on.
A conventional lighting device includes a dimming control unit, which is a control circuit configured using a comparator, a logic circuit, and the like for fading in, and this dimming control unit has a minimum controllable current limit value. When the current value is less than the preset minimum output current, the on / off duty ratio of the transistor is adjusted to a preset voltage as a voltage for flowing the minimum output current to the light emitting unit (for example, Patent Document 1).

JP 2007-234415 A (columns 0026 to 0035, FIG. 3)

However, in the conventional lighting control circuit such as a power source for fade-in lighting, there is a problem that the variation in performance of each lighting device due to the variation in the performance of the elements used for the substrate, particularly the variation in the brightness of the light source becomes large. there were. In addition, there is a problem that it takes time to manufacture the lighting device if the current flowing to the light source is adjusted for each device at the time of manufacturing in order to eliminate the variation in performance of each lighting device.
An object of the present invention is to provide a lighting control device capable of fading in when power is turned on, suppressing variations in performance among lighting devices and easily manufactured, and a lighting device including the lighting control device.

In order to solve the above problems, a lighting control device of the present invention includes a conversion circuit that converts an alternating current supplied from an external AC power source into a direct current, and a lighting circuit that supplies the current converted by the conversion circuit to a light source. And a lighting control circuit that controls a current flowing from the lighting circuit to the light source and includes a first control unit provided with power storage means and a second control unit provided with a variable resistor, The first control unit outputs a signal based on a voltage charged in the power storage unit after AC power is supplied from the AC power source to the second control unit as a first lighting signal , and the second control unit The unit divides the first lighting signal using the variable resistor and outputs the divided voltage to the lighting circuit as a second lighting signal.

The lighting control device of the present invention includes a conversion circuit that converts an alternating current supplied from an external AC power source into a direct current, a lighting circuit that supplies a current converted by the conversion circuit to a light source, and the lighting circuit. A lighting control circuit that controls a current flowing through the light source and includes a first control unit provided with a first power storage unit and a second power storage unit, and a second control unit provided with a variable resistor. The lighting control circuit outputs, as a first lighting signal, a signal based on a voltage charged in the first power storage unit after an alternating current is supplied from the alternating current power source to the second control unit, and then A signal based on a voltage charged in the second power storage unit is output as the first lighting signal to the second control unit, and the second control unit outputs the first lighting signal to the variable resistor. To divide the voltage as a second lighting signal. To being to output the lamp circuit.

  Moreover, the lighting device of the present invention includes any one of the lighting control devices and a light source that is lit by a current supplied from the lighting circuit of the lighting control device.

  According to the present invention, the first lighting signal output from the first lighting control unit is divided by a variable resistor provided in the second control unit, thereby suppressing variation in performance among lighting devices, and The manufacturing efficiency of the lighting device can be increased.

FIG. 3 is a circuit diagram of the lighting device 100 and the lighting control circuit 13 according to the first embodiment of the present invention. FIG. 2 is a detailed circuit diagram of the lighting device 100 and the lighting control circuit 13 according to the first embodiment of the present invention. The time chart figure which shows the relationship between the time t of the lighting device 100 of Embodiment 1 of this invention, a voltage, and an electric current. FIG. 3 is a circuit diagram of another lighting device 110 and a lighting control circuit 13a according to Embodiment 1 of the present invention. The circuit diagram of the lighting device 120 of Embodiment 2 of this invention. The time chart which shows the relationship between the time t of the lighting device 120 of Embodiment 2 of this invention, a voltage, and an electric current.

Embodiment 1 FIG.
1 and 2 are circuit diagrams showing the lighting control circuit 13 and the lighting device 100 according to the first embodiment.
The lighting device 100 is obtained from an AC-DC conversion circuit 11 that receives a commercial power supply AC (alternating current) from the outside and converts an AC voltage supplied from the commercial power supply AC into a DC voltage, and an AC-DC conversion circuit 11. The lighting circuit 12 supplies power to the light source LA. A lighting control circuit 13 and a light source current detection circuit 14 are connected to the lighting circuit 12. The light source LA is a semiconductor light emitting element such as an LED (Light Emitting Diode) or an organic EL (Organic Electro-Luminescence).

  The AC-DC conversion circuit 11 rectifies and outputs AC power supplied from the commercial AC power supply AC, and a smoothing capacitor C12 that smoothes the rectified voltage output from the diode bridge DB and converts it into a DC voltage. And.

  The light source current detection circuit 14 detects the value of the current flowing through the light source LA with the resistor R1 serving as a current detection means or the potential difference generated with the resistor R1 and outputs the detected value to the lighting control circuit 13. The resistor R1 is a shunt resistor or the like.

  The lighting control circuit 13 controls the lighting circuit 12 so that the current flowing through the light source LA is constant based on the value of the current flowing through the light source LA input from the light source current detecting means 14. The lighting control circuit 13 includes a first lighting control unit 15 and a second lighting control unit 16. Details of the first lighting control unit 15 and the second lighting control unit 16 will be described later.

The lighting circuit 12 is a so-called flyback type constant current circuit. The lighting circuit 12 includes a transformer TR, a MOSFET Q11 serving as switching means, and a lighting control IC for controlling on / off of the MOSFET Q11.
The lighting control IC inputs the lighting signal output from the lighting control circuit 13, and based on this lighting signal, the MOSFET Q11 is turned on / off to adjust the duty ratio so that the current flowing through the light source LA becomes constant. The constant current is controlled as follows.
The transformer TR is connected to both ends of the capacitor C12 of the AC-DC conversion circuit 11, and the primary winding T1 and the secondary winding T2 that generates a voltage corresponding to the winding ratio of the primary winding T1, T3 is provided. The lighting circuit 12 includes a resistor R12 connected to the secondary winding T3 of the transformer TR, a diode D11, and a control capacitor C11 connected to the cathode of the diode D11. The diode D11 has an anode connected to the resistor R12 and a cathode connected to the control capacitor C11.
The lighting control IC is connected between the AC-DC conversion circuit 11 and the transformer TR via the resistor R11, and obtains starting power from the rectified voltage rectified by the AC-DC conversion circuit 11. In addition, the transformer TR is connected to a secondary winding T3 as a secondary winding to which a resistor R12 and a diode D11 are connected, so that the control power supply Vcc can be supplied after startup by switching the MOSFET Q11.
The control power supply Vcc supplies the output of the AC-DC conversion circuit 11 to the lighting control IC via the resistor R11, and starts the lighting control IC immediately after the power is turned on.

  In the secondary winding T2 on the secondary side of the transformer TR, the high frequency voltage obtained by switching the MOSFET Q11 is smoothed by the diode D10 and the electrolytic capacitor C10 and supplied to the light source LA.

  In the first lighting control unit 15 of the lighting control circuit 13, the resistor R2 and the resistor R3 are connected in series to the control power source Vcc, and the voltage obtained by dividing the voltage between the resistor R2 and the resistor R3 is supplied to the resistor R4. To the capacitor C1, which is a storage means. The capacitor C1 is charged by the control voltage Vcc divided by the resistors R2 and R3. The voltage charged in the capacitor C1 is output to the non-inverting terminal of the operational amplifier IC1. The output terminal of the operational amplifier IC1 is connected to the inverting terminal of the operational amplifier IC1, and the output of the operational amplifier IC1 is input to the inverting terminal of the operational amplifier IC1. Therefore, the operational amplifier IC1 stably outputs the voltage obtained by the capacitor C1. When the resistance R4 is sufficiently larger than the resistances R2 and R3, the charging time constant of the capacitor C1 is obtained from the capacitances of the resistance R4 and the capacitor C1 regardless of the resistance values of the resistances R2 and R3.

  The voltage obtained from the output terminal of the operational amplifier IC 1 of the first lighting control unit 15 is output to the second lighting control unit 16. The voltage output from the operational amplifier IC1 is resistance-divided by the resistor R5 and the variable resistor VR and input to the non-inverting terminal of the operational amplifier IC2 of the second lighting control unit 16. Note that a capacitor C2 is connected to the non-inverting terminal of the operational amplifier IC2, and noise from the voltage input to the non-inverting terminal of the operational amplifier IC2 is removed by the capacitor C2. Since the capacitor C2 has a small capacity for mainly removing noise at the voltage at the point B, the lighting device 100 may be configured without the capacitor C2.

  Since the light source current detection circuit 14 is provided with a resistor R1 and one end of the resistor R1 is grounded, a voltage proportional to the current flowing through the light source LA can be detected. The voltage generated in the resistor R1 is input to the inverting terminal of the operational amplifier IC2 of the second lighting control unit 16. The voltage input to the inverting terminal from the light source current detection circuit 14 and the voltage charged in the capacitor C2 (the voltage output from the operational amplifier IC1 and divided by the resistor R5 and the variable resistor VR) are compared by the operational amplifier IC2, and the operational amplifier IC2 Outputs a control signal to the lighting circuit 12 so that the current flowing through the light source LA becomes a constant current.

  FIG. 3 is a time chart showing the relationship between the output voltage of each part of the lighting device shown in FIGS. 1 and 2 and the light source current. The vertical axis represents each output voltage and light source current described later, and the horizontal axis represents time t.

When the commercial power supply AC power supply starts at time t0, then the power supply is supplied to the control power supply Vcc at time t1. When the control power supply Vcc rises, the voltage at the point A, that is, the capacitor C1, is charged exponentially based on the charging time constants of the resistors R2, R3, R4 and the capacitor C1. At time t2, the voltages at points A and B and the current flowing through the light source LA are stabilized.
The relationship between the voltage charged in the capacitor C1 and the time T can be obtained by the following equation (1).

A voltage obtained by dividing the voltage at the point A by the resistor R5 and the variable resistor VR is applied to the point B. The lighting control IC of the lighting circuit 12 performs on / off control of the MOSFET Q11 so that the voltage at the point B becomes equal to the voltage generated in the resistor R1.
From this, the voltage change at point A is equal to the change in the current flowing through the light source LA, and the light source LA can be turned on in a fade-in manner. The relationship between the light source current for fade-in lighting and the time t is as shown in the equation (1), but it is necessary to make the length so that the user does not feel uncomfortable in actual use.

It is difficult for the user to recognize that the fade-in light is turned on in a short time change, and conversely, in a long time, a long time is required until all the lights are turned on.
Therefore, when statistics are taken for general users, it is preferable that the circuit used for the calculation of Equation (1) preferably requires about 3 seconds from when the commercial power supply AC is turned on until it reaches a constant voltage. Obtained. It has been found that general users tend to feel that 2 seconds to 4 seconds is preferable when it is fast for 1 second or less and slow for 5 seconds or more.

  The variable resistor VR has a purpose of eliminating variations in light source current for each lighting device. The current flowing through the light source LA under constant current control by the lighting control IC is determined by a value determined by the resistors R1, R2, R3, R4 and the offset voltage of the operational amplifier IC1. Since the offset voltages of the resistors R1, R2, R3, and R4 and the operational amplifier IC1 have a solid variation, as a result, the light source current varies for each lighting device. In order to absorb this variation, the voltage at point B is varied by adjusting the resistance value of the variable resistor VR on the production line, and as a result, the variation in the light source current for each lighting device can be eliminated. At that time, the resistance value of the variable resistor VR is adjusted on the production line so that the time from time t0 to time t2 is about 3 seconds.

In the present invention, the variable resistance VR is provided in the second lighting control unit 16 and the resistance value is adjusted on the production line. Here, the necessity of the second lighting control unit 16 will be described.
For example, consider a lighting device having no second lighting control unit 16. In the first lighting control unit 15, if the inverting input terminal side of the operational amplifier IC 1 inputs the detection voltage of the resistor R 1 of the light source current detection circuit 14 and the output terminal is connected to the lighting circuit 12, the light source current can be faded in. It is.
However, the constant current controlled value is determined by the values determined by the offset voltages of the resistors R1, R2, R3, and R4 and the operational amplifier IC1 as described above, and the offset of the resistor and the operational amplifier IC1 has a solid variation. The light source current varies for each lighting device.

  Therefore, for example, by changing the resistor R3 to a variable resistor so as to absorb solid variations in the offset voltage of the resistors R1, R2, R3, R4 and the operational amplifier IC1, the resistance value of the variable resistor is changed on the production line. If the adjustment is performed, the variation among the lighting devices can be eliminated.

However, when the variable resistor is used in the first lighting control unit 15 in this way, the change time of the target value of the light source current is delayed so that the fade-in lighting is performed. turn into.
That is, when adjusting the resistance value of the variable resistor in the first lighting control unit 15 on the production line, it takes several seconds for the current flowing through the light source LA to stabilize, so adjustment for each lighting device is required. It takes time and manufacturing efficiency deteriorates.

  Therefore, as in the second lighting control unit 16 of the present invention, the variable resistor VR is divided from the first lighting control unit 15 that generates the fade-in lighting time, and a circuit is assembled to the second lighting control unit 16. Since the variable resistor VR is provided, the response of the light source current to the adjustment of the variable resistor VR is good, and it takes a short time to stabilize the current flowing through the light source LA that occurs when adjusting the resistance value of the variable resistor VR. . Therefore, the current supplied to the light source LA for each lighting device can be adjusted in a short time, and variations in lighting devices can be eliminated and the lighting device can be easily manufactured.

  FIG. 4 shows another lighting device 110 of the first embodiment. Differences between the lighting device shown in FIG. 1 and the lighting device shown in FIG. 4 will be described.

  The lighting device 110 includes a lighting control circuit 13a. The lighting control circuit 13a includes a first lighting control unit 15a, a second lighting control unit 16, and a dimming signal circuit 20. In addition, since the 2nd lighting control part 16 is the structure similar to the 2nd lighting control part 16 of the lighting device 100, it is as having mentioned above about the detailed structure.

  A dimming signal 200 is input to the dimming signal processing circuit 20 from the outside of the lighting device 110. This dimming signal is a PWM signal. The dimming signal 200 input to the dimming signal processing circuit 20 is input to the photocoupler PC via the diode bridge DB2. In this diode bridge DB2, since the dimming signal 200 is inputted from the outside, even if the polarity is wrong, the photocoupler PC connected to the subsequent stage of the diode bridge DB is synchronized with the PWM as designed. Can be switched.

The voltage at the point A is determined based on the time constant obtained from the resistors R2a, R3a, R4a, and the capacitor C1a from the voltage obtained from the photocoupler PC switched in synchronization with the PWM signal, and the control shown in FIG. It will be the same.
The voltage at point A may be a voltage obtained from a dimming signal input from the outside.

Embodiment 2. FIG.
FIG. 5 shows a circuit diagram of the lighting device 120 and the lighting control circuit 13b according to the second embodiment. Compared with the lighting device 100 and the lighting control circuit 13 of the first embodiment, the fade-in lighting after power-on is visually improved. In the second embodiment, the difference between the first lighting control unit 15 of the first embodiment will be mainly described. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

A resistor R6 and a resistor R7 are connected in parallel to the control power supply Vcc, the gate of the MOSFET Q1 is connected to the resistor R6, and the gate of the MOSFET Q2 is connected to the resistor R7 and the capacitor C4. The resistor R7 and the capacitor C4 are connected in series, and the gate of the MOSFET Q2 is connected between the resistor R7 and the capacitor C4.
Capacitor C3 is connected to the collector of MOSFET Q1, and resistor R2b is connected to capacitors C3 and C1b. The gate of MOSFET Q1 is connected to the collector of MOSFET Q2.

  FIG. 6 is a time chart showing the relationship between the output voltage, light source current, and time t of each part of the lighting device 120 shown in FIG. 5 of the second embodiment. The operation of the lighting device 120 will be described with reference to FIG.

When the commercial power supply AC starts supplying alternating current at time t0, power is then supplied to the control power supply Vcc at time t1.
The voltage at point C (the gate of MOSFET Q2) is determined by the charging time constant of resistor R7 and capacitor C4. When the voltage at point C does not reach the turn-on of MOSFET Q2, MOSFET Q1 is in the off state. That is, when the capacitor C4 is charged to a certain threshold value, the MOSFET Q2 is turned on, and a current flows from the collector to the emitter of the MOSFET Q2, so that the voltage at the gate of the MOSFET Q1 is lowered and the MOSFET Q1 is turned off.
Therefore, when the control power supply Vcc rises after the power is turned on, the voltage at the point A from time t1 to time t2, that is, the capacitor C1 and the capacitor C3 are charged based on the charging time constant of the resistor R2, the capacitor C1, and the capacitor C3. Is done.

  At time t2 when the voltage at point C reaches the turn-on of the MOSFET Q2, the MOSFET Q2 is turned on and the MOSFET Q1 is turned off. When MOSFET Q1 is turned off, no current flows through capacitor C3, and after time t2, capacitor C1b is charged exponentially based on the charging time constant of resistor R2b and capacitor C1b. The voltage at both ends of the capacitor C1b becomes the voltage at the point A in FIG. In the operational amplifier IC1b, the output is fed back and input to the inverting input terminal, and the input value from the non-inverting input terminal is compared with the input value from the inverting terminal. Therefore, the operational amplifier IC1b stably outputs the voltage obtained by the capacitor C1b.

  From time t1 to time t2 and after time t2, the time constant at which point A is charged differs due to the presence or absence of the capacitor C3 or the capacitance of the capacitor C3. Therefore, as described above, the fade-in lighting immediately after the power is turned on is determined by the voltage fluctuation at the point A. Therefore, since the capacitor C3 is connected from the time t1 to the time t2, the fade-in lighting can be performed slowly. This is because a fade-in lighting that is as slow as possible is more easily recognized as a fade-in lighting, and is considered to be visually preferable. However, if the fade-in lighting is performed slowly, it takes time until the stable maximum output is reversed. Thus, the current flowing through the light source LA at the timing when the MOSFET Q1 is turned off during the fade-in lighting is thus inflection point. It is visually preferable to provide.

  As described above, in the lighting control device 13b and the lighting device 120 according to the second embodiment, since the inflection point is provided in the light source current during the fade-in lighting, the lighting device is visually preferable for the user. be able to.

  The present invention can be used for a lighting device using an LED or an organic EL.

  11 AC-DC conversion circuit, 12 lighting circuit, 13 lighting control circuit, 14 current detection circuit, 15 first lighting control unit, 16 second lighting control unit, 20 dimming signal processing circuit, IC1 to IC2 operational amplifier, 200 Dimming signal, AC commercial power supply, C1-C4, C10-C12 capacitor, R1-R7, R11-R12 resistor, VR variable resistor, Q1-Q2, Q11 MOS-FET, PC photocoupler, D10-D11 diode, TR transformer , Vcc control power supply, LA light source.

Claims (4)

A conversion circuit that converts alternating current supplied from an external alternating current power source into direct current;
A lighting circuit for supplying a light source with the current converted by the conversion circuit;
A lighting control circuit that controls a current flowing from the lighting circuit to the light source, and includes a first control unit provided with power storage means and a second control unit provided with a variable resistor;
The first control unit outputs a signal based on a voltage charged in the power storage unit after AC power is supplied from the AC power source to the second control unit as a first lighting signal,
The lighting control device, wherein the second control unit divides the first lighting signal using the variable resistor and outputs the divided voltage to the lighting circuit as a second lighting signal. The first control unit has a comparator to which the voltage of the power storage means is input,
2. The lighting according to claim 1, wherein the comparator compares the input voltage of the power storage unit with a feedback output and outputs the voltage of the power storage unit as the first lighting signal. Control device. A conversion circuit that converts alternating current supplied from an external alternating current power source into direct current;
A lighting circuit for supplying a light source with the current converted by the conversion circuit;
A lighting control circuit which controls a current flowing from the lighting circuit to the light source and includes a first control unit provided with a first power storage unit and a second power storage unit and a second control unit provided with a variable resistor. And comprising
The lighting control circuit outputs a signal based on a voltage charged in the first power storage unit after an alternating current is supplied from the alternating current power source to the second control unit as a first lighting signal, and then A signal based on the voltage charged in the second power storage means is output to the second controller as the first lighting signal;
The lighting control device, wherein the second control unit divides the first lighting signal using the variable resistor and outputs the divided voltage as a second lighting signal to the lighting circuit. A lighting control device according to any one of claims 1 to 3,
A light source that is lit by a current supplied from the lighting circuit of the lighting control device;
A lighting device comprising:

Images