JP2009199901A - Control circuit, lighting device for discharge lamp, and illumination fixture - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To rapidly and correctly determine whether or not a load circuit 200 is inputting an alternate current voltage from an alternate current power supply AC. <P>SOLUTION: The load circuit 200 inputs the alternate current voltage from the alternate current power supply AC, and is operated. A power supply detection circuit includes a resistor R11, a capacitor C12, and a current detection circuit 120. The current detection circuit 120 forms a detection voltage v<SB>2</SB>based on the current flowing in the resistor R11. The resistor R11 and the capacitor C12 are electrically connected in series. The load circuit 200 and the power supply detection circuit are electrically connected in parallel. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control circuit that determines the presence or absence of an AC voltage and controls the circuit in a circuit such as a discharge lamp lighting device that operates by inputting an AC voltage from an AC power source such as a commercial power source.

There is a control circuit that detects energization and power failure of an AC power source and controls the circuit based on the detection result.
JP 2003-249382 A JP-A-3-269996 Japanese Patent Laid-Open No. 7-57887

If there is a capacitor at the input stage of the circuit, the charged voltage may remain in the capacitor even if the AC power supply is cut off due to a power failure or the like.
The present invention has been made, for example, in order to solve the above-described problems, and an object thereof is to promptly and correctly determine whether or not a circuit is inputting an AC voltage from an AC power source.

The control circuit according to the present invention includes:
A power detection circuit having a resistor, a capacitor, and a current detection circuit that generates a detection voltage based on a current flowing through the resistor, wherein the resistor and the capacitor are electrically connected in series;
A load circuit that operates by inputting an AC voltage from an AC power source;
A determination circuit for determining whether the load circuit is inputting the AC voltage from the AC power source based on a detection voltage generated by the power source detection circuit;
The load circuit and the power supply detection circuit are electrically connected in parallel.

  According to the control circuit of the present invention, when the AC voltage from the AC power supply is not input, the voltage at the input terminal of the load circuit does not become zero due to the charge remaining in the capacitor of the load circuit. In addition, there is an effect that it is possible to quickly detect that the AC voltage is not input from the AC power source.

Embodiment 1 FIG.
The first embodiment will be described with reference to FIGS.

FIG. 1 is a block configuration diagram showing a rough configuration of the control circuit 100 in this embodiment.
The control circuit 100 includes a load circuit 200, a power supply detection circuit 110, and a determination circuit 131.

  The load circuit 200 is a circuit that receives an AC voltage from an AC power source AC such as a commercial power source and operates with the input AC voltage. The load circuit 200 has two voltage input terminals 201 and 202. The load circuit 200 inputs the potential difference between the two voltage input terminals 201 and 202 as an AC voltage.

  The power supply detection circuit 110 (power supply synchronization circuit) is electrically connected to the load circuit 200 in parallel. That is, one of the two input terminals of the power supply detection circuit 110 is electrically connected to the voltage input terminal 201 and the other is electrically connected to the voltage input terminal 202. The power supply detection circuit 110 includes a resistor R11, a capacitor C12, and a current detection circuit 120. The resistor R11, the capacitor C12, and the current detection circuit 120 are electrically connected in series. The current detection circuit 120 generates a detection voltage based on the current flowing through the resistor R11.

The determination circuit 131 determines whether or not the load circuit 200 is inputting an AC voltage based on the detection voltage generated by the current detection circuit 120 of the power supply detection circuit 110.
The case where the load circuit 200 does not input an AC voltage is, for example, when the power switch SW is turned off or when a power failure occurs.

  The control circuit 100 controls the operation of the load circuit 200 based on the determination result of the determination circuit 131. For example, the control circuit 100 switches the power consumption of the load circuit 200 based on the ON / OFF operation of the power switch SW, or detects an instantaneous power failure (instantaneous power failure) or a sag (instantaneous voltage drop), thereby normalizing the load circuit 200. The operation is maintained, or a power failure is detected, and the operation of the load circuit 200 is continued by switching to an emergency power source.

  FIG. 2 is an electric circuit diagram showing a part of the circuit configuration of the control circuit 100 in this embodiment.

The load circuit 200 includes a voltage drop circuit 210, a DC power supply circuit 230, and a circuit 220.
The circuit 220 is a circuit that operates using a DC voltage as a power source.
The DC power supply circuit 230 is a circuit that receives an AC voltage and generates a DC voltage for operating the circuit 220.
The voltage drop circuit 210 is a circuit that reduces (decreases) the voltage of the AC voltage input by the load circuit 200 and suppresses power loss in the DC power supply circuit 230. The voltage drop circuit 210 includes a capacitor C13 (current reducing element), a diode D14 (half-wave rectifying element), and a diode D15 (discharge element).
One of the two terminals of the capacitor C13 is electrically connected to the voltage input terminal 201.
The other terminal of the two terminals of the capacitor C13, the anode terminal of the diode D14, and the cathode terminal of the diode D15 are electrically connected to each other.
The cathode terminal of the diode D14 is electrically connected to the input terminal of the DC power supply circuit 230.
The anode terminal of the diode D15 is electrically connected to the voltage input terminal 202 via the ground wiring GND.

When the potential of the voltage input terminal 201 becomes high and current flows from the voltage input terminal 201 into the load circuit 200, the capacitor C13 is charged by the flowing current. The flowing current is supplied to the DC power supply circuit 230 via the diode D14.
Further, when the potential of the voltage input terminal 201 becomes low and current flows out from the load circuit 200 to the voltage input terminal 201, the capacitor C13 is discharged by the outflowed current. The flowing current is supplied from the voltage input terminal 202 via the diode D15.
As described above, the capacitor C13 repeats charging and discharging every cycle of the input AC voltage. In addition, since the voltage input to the DC power supply circuit 230 is lowered by the voltage charged in the capacitor C13, power loss in the DC power supply circuit 230 can be suppressed.

The current detection circuit 120 includes a photocoupler PC, a resistor R21, and a capacitor C22.
The photocoupler PC (switch element, bidirectional photocoupler) has two light emitting diodes and a phototransistor. The two light emitting diodes are connected in parallel with opposite polarities between the two input terminals of the photocoupler PC. The phototransistor has a collector terminal connected to the anode-side output terminal and an emitter terminal connected to the cathode-side output terminal of the photocoupler PC. The phototransistor receives light emitted from the two light-emitting diodes and is turned on / off.
The two input terminals of the photocoupler PC are electrically connected in series with the resistor R11 and the capacitor C12, and input a current flowing through the resistor R11 and the capacitor C12.
One terminal of the two terminals of the resistor R21 is electrically connected to the DC voltage wiring _VCC . The DC voltage wiring _VCC is electrically connected to a DC power supply such as a DC power supply circuit 230, for example.
The other terminal of the two terminals of the resistor R21, the anode side output terminal of the photocoupler PC, and one of the two terminals of the capacitor C22 are electrically connected to each other.
The cathode side output terminal of the photocoupler PC and the other terminal of the two terminals of the capacitor C22 are electrically connected to each other.
Current detecting circuit 120, the voltage across the capacitor C22, and outputs it as a detection voltage _{v 2.}

If the absolute value of the input current of the photocoupler PC is smaller than the value phototransistor is turned on, the capacitor C22 is charged by the current supplied from the DC voltage line V _CC through a resistor R21, a current detection circuit 120 The detection voltage v ₂ that is substantially equal to the potential of the DC voltage wiring _VCC is output.
Absolute value of the input current of the photo-coupler PC is, when the phototransistor is greater than the value which is turned on, the capacitor C22 discharges through the phototransistor, the current detection circuit 120 outputs a substantially detected voltage v ₂ 0 .

FIG. 3 is a waveform diagram showing the voltage and current of each part of the control circuit 100 in this embodiment.
The horizontal axis represents time, and the vertical axis represents voltage or current. The voltage v _IN (thick line) is an AC voltage input by the control circuit 100. The voltage v _C (thick line) is the voltage across the capacitor C12. The voltage v ₁ (thin line) is a voltage across the capacitor C13 of the voltage drop circuit 210. The current i _R is a current flowing through the resistor R11. The voltage v ₂ is a detection voltage output from the current detection circuit 120.

When the voltage v _IN increases, the capacitor C12 and the capacitor C13 are charged following the increase, and the voltage v _C and the voltage v ₁ increase. Further, when the voltage v _IN is lowered, the capacitor C12 and the capacitor C13 are discharged following this, and the voltage v _C and the voltage v ₁ are lowered.
Since the power supply detection circuit 110 is a CR series circuit, the current i _R flowing through the resistor R11 is a current whose phase is higher than that of the voltage v _IN . Voltage v ₂ becomes a high potential in the vicinity of the current i _R crosses zero, the low potential otherwise.
Therefore, when the load circuit 200 receives an AC voltage, the detection voltage v ₂ generated by the current detection circuit 120 is a rectangular wave having a frequency twice that of the AC voltage input by the load circuit 200. That is, the current detection circuit 120 generates a signal synchronized with the AC voltage input by the load circuit 200.

It is assumed that the control circuit 100 stops inputting an AC voltage at time t ₁ because the power switch SW is turned off.

Even if power is turned off, the capacitor C13 is not discharged immediately, voltage v ₁ is not zero. The voltage v _IN is substantially equal to the voltage v ₁ .
Therefore, the voltage corresponding to the difference between the voltages v ₁ and the voltage v _C is applied to the resistor R11, even after the power switch SW has expired, the current flows i _R.
The current i _R discharges the capacitor C13 and charges the capacitor C12. When the voltage v ₁ and the voltage v _C are equal, the current i _R does not flow.
The time taken until the current i _R does not flow is determined by the resistance value of the resistor R11 and the capacitance values of the capacitors C12 and C13.

If the absolute value of the current i _R is smaller than a predetermined value, since the detected voltage v ₂ of the current detecting circuit 120 generates becomes a high potential, the high potential immediately power off.
Therefore, when the control circuit 100 stops inputting the AC voltage due to disconnection of the power switch SW, power failure, or the like, the control circuit 100 can detect this immediately without any delay.

For comparison, consider a control circuit without the capacitor C12.
Note that the control circuit of the comparative example is the same as the control circuit 100 in this embodiment except that the capacitor C12 is not provided and the resistor R11 and the current detection circuit 120 are directly connected.

  FIG. 4 is a waveform diagram showing voltages and currents in various parts of the control circuit of the comparative example.

When the control circuit inputs an AC voltage, the current i _R is substantially in phase with the voltage v _IN because there is no capacitor C12. Therefore, the detection voltage v ₂ is the timing out of the pulse are different, similar to the control circuit 100 in this embodiment, a rectangular wave of times the frequency of the AC voltage input.

However, the operation in the case where the control circuit stops inputting the AC voltage due to the power switch SW being turned off at time t ₁ is greatly different.
The current i _R flows due to the voltage remaining in the capacitor C13, and the capacitor C13 is discharged. The current i _R continues to flow until the capacitor C13 is completely discharged.
For this reason, the control circuit of the comparative example cannot be detected immediately even if the control circuit stops inputting the AC voltage.

In the control circuit of the comparative example, the time taken until the current i _R stops flowing is determined by the resistance value of the resistor R11 and the capacitance value of the capacitor C13. However, reducing the resistance of the resistor R11, the current i _R increases, increases power consumption in the power supply detection circuit. Further, since the capacitance value of the capacitor C13 is determined by the current required by the DC power supply circuit 230, it cannot be made too small.

In contrast, control circuit 100 in this embodiment, by adjusting the capacitance of the capacitor C12, can freely adjust the time it takes the current i _R stops flowing. If the capacitance value of the capacitor C12 is reduced, the time taken until the current i _R stops flowing can be shortened. Therefore, when the control circuit 100 stops inputting the AC voltage, it can be detected almost without delay.

The control circuit 100 in this embodiment includes a power supply detection circuit 110, a load circuit 200, and a determination circuit 131. The power supply detection circuit 110 includes a resistor R11, a capacitor C12, and a current flowing through the resistor R11. and a current detecting circuit 120 for generating a detection voltage v ₂ on the basis of i _R, the resistor R11 and the above capacitor C12 is electrically connected in series, the load circuit 200 inputs the AC voltage from the AC power source AC The determination circuit 131 determines whether the load circuit 200 is inputting the AC voltage from the AC power source AC based on the detection voltage v ₂ generated by the power source detection circuit 110. Since the load circuit 200 and the power source detection circuit 110 are electrically connected in parallel, when the AC voltage from the AC power source AC is not input, the load circuit 200 and the power source detection circuit 110 are negative. Even when the voltage at the input terminal of the load circuit 200 does not become zero due to, for example, charge remaining in the capacitor of the circuit 200, it is possible to quickly detect that the AC voltage is not input from the AC power supply AC. There is an effect that can be done.

Since the current detection circuit 120 in this embodiment generates the detection voltage v ₂ having a predetermined potential (approximately V _CC ) when the current i _R flowing through the resistor R11 is within a predetermined range including 0, If the load circuit 200 is input AC voltage, when the detection voltage v _2, becomes a rectangular wave of times the frequency of the frequency of the AC voltage, the load circuit 200 has not entered an AC voltage is detected It becomes a voltage v ₂ is approximately V _CC, whether the load circuit 200 is input to an AC voltage, an effect that the decision circuit 131 can be easily determined.

The load circuit 200 in this embodiment has two voltage input terminals 201 and 202 for inputting the AC voltage and a second capacitor C13, and one of the two voltage input terminals. 201 and one terminal of the second capacitor C13 are electrically connected, so that when the AC voltage is no longer input from the AC power supply AC, the voltage charged in the capacitor C13 remains, and the voltage input terminal 201 Although the potential does not become zero, the capacitor C12 is charged with a voltage substantially equal to the voltage charged in the capacitor C13, so the current i _R flowing through the resistor R11 becomes almost zero, and an AC voltage is input from the AC power supply AC. There is an effect that it can be detected promptly that it has disappeared.

In addition, there is a voltage drop circuit 210 that uses a resistor instead of the capacitor C13, but if a resistor is used, power loss due to the resistor occurs.
Since the control circuit 100 in this embodiment includes the voltage drop circuit 210 using the capacitor C13, power consumption can be suppressed.

Embodiment 2. FIG.
The second embodiment will be described with reference to FIGS.
In this embodiment, an application example of the control circuit 100 described in Embodiment 1 will be described.

FIG. 5 is a perspective view showing the appearance of the lighting fixture 800 in this embodiment.
The lighting fixture 800 includes an LED such as a high-intensity white light-emitting diode, and is a lighting fixture that illuminates an object by causing the LED to emit light.

FIG. 6 is an electric circuit diagram showing a partial circuit configuration of the LED lighting device 810 according to this embodiment.
Note that portions common to the control circuit 100 described in Embodiment 1 are denoted by the same reference numerals, and description thereof is omitted here.

  The lighting fixture 800 includes a lighting device 810 (light emitting diode lighting device, control circuit 100) that lights the LED. The lighting device 810 includes a voltage drop circuit 210, a DC power supply circuit 230, a capacitor C23, a light emitting diode lighting circuit 240, and a switching element Q24 as the load circuit 200.

The DC power supply circuit 230 is a circuit that inputs the voltage dropped by the voltage drop circuit 210 and generates a stable DC voltage. The DC power supply circuit 230 includes a constant voltage diode ZD31, a capacitor C32, a resistor R33, a constant voltage diode ZD34, and a transistor Q35.
The constant voltage diode ZD31 and the constant voltage diode ZD34 are, for example, Zener diodes.
The transistor Q35 is, for example, an NPN bipolar transistor.
The cathode terminal of the constant voltage diode ZD31, one of the two terminals of the capacitor C32, one of the two terminals of the resistor R33, and the collector terminal of the transistor Q35 are both output from the voltage drop circuit 210. The terminal (the cathode terminal of the diode D14) is electrically connected.
The anode terminal of the constant voltage diode ZD31, the other terminal of the two terminals of the capacitor C32, and the anode terminal of the constant voltage diode ZD34 are both electrically connected to the ground wiring GND.
The other of the two terminals of the resistor R33, the cathode terminal of the constant voltage diode ZD34, and the base terminal of the transistor Q35 are electrically connected to each other.
The emitter terminal of the transistor Q35 is electrically connected to one of the two terminals of the capacitor C23 as an output terminal of the DC power supply circuit 230.
The other terminal of the two terminals of the capacitor C23 is electrically connected to the ground wiring GND.

Capacitor C32 is charged by the current flowing from voltage drop circuit 210.
The constant voltage diode ZD31 is a safety circuit for preventing the voltage charged in the capacitor C32 from becoming higher than a predetermined voltage.
The constant voltage diode ZD34 generates a reference voltage that determines the DC voltage generated by the DC power supply circuit 230.
When the difference between the Zener voltage of the constant voltage diode ZD34 and the voltage charged in the capacitor C23 becomes higher than the on-voltage (for example, 0.6 V) between the base and emitter of the transistor Q35, the base is connected to the transistor Q35 via the resistor R33. A current is supplied, the transistor Q35 is turned on, and a current for charging the capacitor C23 flows through the transistor Q35. As a result, the capacitor C23 is always charged with the voltage of the Zener voltage −0.6V of the constant voltage diode ZD34.

The light emitting diode lighting circuit 240 includes an LED, and lights up by applying a DC voltage charged in the capacitor C23 to the LED.
The switching element Q24 is, for example, an NPN-type bipolar transistor, and is electrically connected in series with the light emitting diode lighting circuit 240. When the switching element Q24 is turned on, the voltage charged in the capacitor C23 is applied to the light emitting diode lighting circuit 240, and the light emitting diode lighting circuit 240 lights the LED. When the switching element Q24 is turned off, the direct current voltage charged in the capacitor C23 is not applied to the light emitting diode lighting circuit 240, and thus the LED is turned off.

DC voltage line _{V CC} is electrically connected to the output terminal of the DC power supply circuit 230 (emitter terminal of the transistor Q35).

A microcomputer (hereinafter referred to as "microcomputer".) 130 is electrically connected to a DC voltage line V _CC, via a DC voltage line V _CC, inputs a DC voltage DC power supply circuit 230 is generated, the input DC voltage Operates as a power source.
The microcomputer 130 implements various functions by executing programs stored in a storage device such as a ROM (not shown).

The determination circuit 131 is realized by the microcomputer 130 executing a program. The determination circuit 131 may be realized by an analog circuit, a digital circuit, an analog / digital mixed circuit, or the like.
The determination circuit 131 receives the detection voltage v ₂ generated by the current detection circuit 120. Judging circuit 131 judges whether the detected voltage v ₂ input higher or lower than a predetermined voltage. In the following description, a state where the detection voltage v ₂ is higher than a predetermined voltage is referred to as “H”, and a state where the detection voltage v ₂ is lower than the predetermined voltage is referred to as “L”.
The determination circuit 131 determines that the lighting device 810 does not input an AC voltage when the “H” state continues for a predetermined time (hereinafter referred to as “continuation determination threshold time”) or longer.

When the lighting device 810 inputs an AC voltage, the detection voltage v ₂ is a rectangular wave having a frequency twice that of the AC voltage, and there is a period in which the detection voltage v ₂ periodically becomes “H”. The continuation determination threshold time is set longer than the length of this period. For example, the continuation determination threshold time is set for one cycle of the AC voltage. Thereby, the determination circuit 131 can correctly determine whether or not the lighting device 810 is inputting an AC voltage.

Note that the determination circuit 131 may determine whether or not the lighting device 810 is inputting an AC voltage by measuring the time from “L” to “H”.
For example, when “L” is changed to “H”, the determination circuit 131 calculates an elapsed time from the time when “L” is changed to “H” last time. When the calculated elapsed time is shorter than a predetermined time (hereinafter referred to as “elapsed determination threshold time”), the determination circuit 131 does not wait for the continuation determination threshold time to elapse, and the lighting device 810 is AC. It is determined that no voltage is input. The elapsed determination threshold time is set to a fixed value in advance when the frequency of the AC voltage is known in advance. When the frequency of the AC voltage is not known in advance, since the determination based on the elapsed determination threshold time cannot be performed at first, the determination circuit 131 determines whether or not to return from “H” to “L” within the continuation determination threshold time. When returning from “H” to “L” within the determination threshold time, it is determined that the lighting device 810 is inputting an AC voltage, and an elapsed time at that time (a margin is given in consideration of frequency variation). Is included as the elapsed determination threshold time, and the determination based on the elapsed determination threshold time and the determination based on the continuation determination threshold time are performed together.

The lighting control circuit 132 is realized by the microcomputer 130 executing a program. The lighting control circuit 132 may be realized by an analog circuit, a digital circuit, an analog / digital mixed circuit, or the like.
The lighting control circuit 132 determines whether to turn on or off the LED based on the determination result determined by the determination circuit 131, and generates a signal for turning on or off the switching element Q24 based on the determination result. Output.

Lighting device 810 of this embodiment (control circuit), the determination circuit 131, based on the detected voltage v ₂ of the current detecting circuit 120 has generated a predetermined range including a current i _R 0 flowing through the resistor R11 Is in the state ("H") for a predetermined time (continuation determination threshold time) or longer, it is determined that the AC voltage is not input. There is an effect that it can be determined.

  In the lighting device 810 (control circuit) in this embodiment, the load circuit 200 has a DC power supply circuit 230 that generates a DC voltage based on the input AC voltage, and the determination circuit 131 (the microcomputer 130) includes: Since the DC voltage generated by the DC power supply circuit 230 operates as a power source, it is possible to easily determine whether or not an AC voltage is input.

  The lighting fixture 800 in this embodiment includes the above-described control circuit (lighting device 810), and the load circuit 200 includes a DC power supply circuit 230 that generates a DC voltage based on the input AC voltage, and a light emitting diode. The LED includes a light emitting diode lighting circuit 240 that applies the DC voltage generated by the DC power supply circuit 230 to the light emitting diode LED, and the control circuit (lighting device 810) further determines the determination result of the determination circuit 131. Since the lighting control circuit 132 that controls the light emitting diode lighting circuit 240 based on the above is detected, it is possible to detect the operation of the power switch SW, a power failure, and the like, and to control the lighting and extinguishing of the LED based on the detection result. There is an effect.

Embodiment 3 FIG.
The third embodiment will be described with reference to FIGS.
In this embodiment, another application example of the control circuit 100 described in Embodiment 1 will be described.

FIG. 7 is a perspective view showing the appearance of the lighting fixture 800 in this embodiment.
The lighting fixture 800 has a lamp socket 801 for connecting the discharge lamp LA, and lights the discharge lamp LA connected to the lamp socket 801.

FIG. 8 is an electric circuit diagram showing a partial circuit configuration of the lighting device 820 in this embodiment.
Note that portions common to the lighting device 810 described in Embodiment 2 are denoted by the same reference numerals, and description thereof is omitted here.

  The lighting fixture 800 includes a lighting device 820 (discharge lamp lighting device, control circuit 100) inside. The lighting device 820 includes a voltage drop circuit 210, a DC power supply circuit 230, a capacitor C23, and an AC power supply circuit 250 as the load circuit 200.

The AC power supply circuit 250 includes a diode bridge DB, a power factor correction circuit 251, an inverter circuit 252, a coil L53, a capacitor C54, and a capacitor C55.
The diode bridge DB receives an AC voltage from the AC power supply AC, and full-wave rectifies the input AC voltage to generate a pulsating voltage.
The power factor correction circuit 251 receives the pulsating voltage generated by the diode bridge DB and boosts or steps down the input pulsating voltage to generate a stable DC voltage. The power factor correction circuit 251 is, for example, a boost chopper circuit.
The inverter circuit 252 receives the DC voltage generated by the power factor correction circuit 251 and generates a high-frequency rectangular wave voltage from the input DC voltage. The inverter circuit 252 is, for example, a half bridge circuit or a full bridge circuit.
The coil L53 is a choke coil that limits the current flowing through the discharge lamp LA.
The capacitor C54 is a coupling capacitor that removes a DC component from the rectangular wave voltage generated by the inverter circuit 252.
When the discharge of the discharge lamp LA is started, the capacitor C55 resonates with the coil L53 and the capacitor C54 to generate a high voltage between the filaments of the discharge lamp LA and start the discharge.

  The lighting control circuit 132 generates and outputs a control signal for controlling the inverter circuit 252 based on the determination result of the determination circuit 131.

  The ground wiring GND is not electrically connected to the voltage input terminal 202 but to one of the two output terminals of the diode bridge DB (cathode side output terminal).

  Even in such a connection, it is possible to correctly determine whether or not an AC voltage is input from the AC power supply AC, as in the first and second embodiments.

  The lighting device 820 (discharge lamp lighting device) in this embodiment includes the control circuit 100 described above, and the load circuit 200 generates an AC voltage to be applied to the discharge lamp LA based on the input AC voltage. Since the control circuit 100 further includes a lighting control circuit 132 that controls the AC power supply circuit 250 based on the determination result of the determination circuit 131, the operation of the power switch SW, a power failure, etc. And the lighting / extinguishing of the discharge lamp LA can be controlled based on the detection result.

  The lighting fixture 800 in this embodiment is configured such that the above-described discharge lamp lighting device (lighting device 820) and the discharge lamp LA are detachably electrically connected, and the AC voltage generated by the discharge lamp lighting device (lighting device 820). And a discharge lamp connection portion (lamp socket 801) that is lit by applying a voltage to the discharge lamp LA. Therefore, an operation of the power switch SW or a power failure is detected, and the discharge lamp connected to the lamp socket 801 is detected based on the detection result. There exists an effect that the lighting / extinguishing of the electric lamp LA can be controlled.

Embodiment 4 FIG.
The fourth embodiment will be described with reference to FIG.
In this embodiment, a modified example of the control circuit 100 described in Embodiment 1 will be described.

FIG. 9 is an electric circuit diagram showing a partial circuit configuration of the lighting device 810 in this embodiment.
Note that portions common to the lighting device 810 described in Embodiment 2 are denoted by the same reference numerals, and description thereof is omitted here.

The power supply detection circuit 110 further includes two constant voltage diodes ZD16 and ZD17.
The two constant voltage diodes ZD16 and ZD17 (trigger elements) are, for example, Zener diodes. The two constant voltage diodes ZD16 and ZD17 are connected in series with opposite polarities, and are electrically connected in series with the resistor R11, the capacitor C12, and the photocoupler PC (the input side thereof).
Therefore, when the voltage exceeds the Zener voltage of the constant voltage diode ZD16 or a constant voltage diode ZD17 is not inputted, the current does not flow i _R the resistor R11.

  The power switch SW is, for example, a firefly switch. The firefly switch is a switch that is used as a power switch of a lighting fixture or the like. When the switch is turned off, a small light is turned on so that the position of the switch can be recognized even in a dark room. For this reason, even if the power switch SW is turned off, the AC voltage input from the AC power source AC to the lighting device 810 does not become zero, and a slight voltage remains.

In such a case, the slightly remaining voltage, the current flows i _R the resistor R11, the current detecting circuit 120 generates a detection voltage v ₂ of the rectangular wave, the determining circuit 131 is likely to erroneously determine .
Therefore, the two constant voltage diode ZD16, ZD17, the power switch SW is in the voltage remaining in the case of off, so that current does not flow _{i R.} Thus, the determination circuit 131 can correctly determine that the power supply due to the power switch SW being turned off has been cut off.

FIG. 2 is a block configuration diagram showing a rough configuration of a control circuit 100 according to the first embodiment. FIG. 2 is an electric circuit diagram illustrating a circuit configuration of part of the control circuit 100 according to the first embodiment. FIG. 3 is a waveform diagram showing voltages and currents of each part of the control circuit 100 according to the first embodiment. The wave form diagram which shows the voltage and electric current of each part of the control circuit of a comparative example. FIG. 10 is a perspective view illustrating an appearance of a lighting fixture 800 according to Embodiment 2. FIG. 6 is an electric circuit diagram illustrating a partial circuit configuration of an LED lighting device 810 according to Embodiment 2. FIG. 10 is a perspective view illustrating an appearance of a lighting fixture 800 according to Embodiment 3. FIG. 10 is an electric circuit diagram illustrating a partial circuit configuration of a lighting device 820 according to Embodiment 3. FIG. 6 is an electric circuit diagram illustrating a partial circuit configuration of a lighting device 810 according to Embodiment 4.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Control circuit, 110 Power supply detection circuit, 120 Current detection circuit, 130 Microcomputer, 131 Judgment circuit, 132 Lighting control circuit, 200 Load circuit, 201,202 Voltage input terminal, 210 Voltage drop circuit, 220 circuit, 230 DC power supply circuit, 240 light-emitting diode lighting circuit, 250 AC power supply circuit, 251 power factor correction circuit, 252 inverter circuit, 800 lighting fixture, 801 lamp socket, 810, 820 lighting device, AC AC power supply, C12, C13, C22, C23, C32, C54 , C55 capacitor, D14, D15 diode, DB diode bridge, GND ground wiring, L53 coil, LA discharge lamp, LED light emitting diode, PC photocoupler, Q24 switching element, Q35 transistor, R11, R21, R33 resistance, W power switch, _{v 2} detected _{voltage, V CC} DC voltage _{wiring, v IN} AC voltage, ZD16, ZD17, ZD31, ZD34 Zener diode.

Claims (8)

A power detection circuit having a resistor, a capacitor, and a current detection circuit that generates a detection voltage based on a current flowing through the resistor, wherein the resistor and the capacitor are electrically connected in series;
A load circuit that operates by inputting an AC voltage from an AC power source;
A determination circuit for determining whether the load circuit is inputting the AC voltage from the AC power source based on a detection voltage generated by the power source detection circuit;
A control circuit, wherein the load circuit and the power source detection circuit are electrically connected in parallel.   The control circuit according to claim 1, wherein the current detection circuit generates a detection voltage having a predetermined potential when a current flowing through the resistor is within a predetermined range including zero. The load circuit has two voltage input terminals for inputting the AC voltage, and a second capacitor,
3. The control circuit according to claim 1, wherein one of the two voltage input terminals is electrically connected to one terminal of the second capacitor. 4.   The determination circuit inputs the AC voltage when a state where the current flowing through the resistor is within a predetermined range including 0 continues for a predetermined time or more based on the detection voltage generated by the current detection circuit. 4. The control circuit according to claim 1, wherein it is determined that the control circuit has not been operated. The load circuit has a DC power supply circuit that generates a DC voltage based on the input AC voltage,
5. The control circuit according to claim 1, wherein the determination circuit operates using a DC voltage generated by the DC power supply circuit as a power supply. 6. A control circuit according to any one of claims 1 to 5,
The load circuit has an AC power supply circuit that generates an AC voltage to be applied to the discharge lamp based on the input AC voltage,
The discharge lamp lighting device, wherein the control circuit further includes a lighting control circuit that controls the AC power supply circuit based on a determination result of the determination circuit. A discharge lamp lighting device according to claim 6,
A lighting fixture comprising: a discharge lamp connecting portion configured to detachably electrically connect the discharge lamp and to apply an AC voltage generated by the discharge lamp lighting device to the discharge lamp. A control circuit according to any one of claims 1 to 5,
The load circuit includes a DC power supply circuit that generates a DC voltage based on the input AC voltage, a light emitting diode, and a light emitting diode lighting circuit that applies the DC voltage generated by the DC power supply circuit to the light emitting diode. And
The control circuit further includes a lighting control circuit that controls the light-emitting diode lighting circuit based on a determination result of the determination circuit.

Images