JP2007294235A - Compact self-ballasted fluorescent lamp, and lighting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact self-ballasted fluorescent lamp capable of securing a predetermined preheating time even when connected to an automatic lighting device; and to provide a lighting system. <P>SOLUTION: This compact self-ballasted fluorescent lamp is provided with: a fluorescent tube 21 having electrodes 22A and 22B; a resonance circuit connected to the electrodes 22A and 22B of the fluorescent tube 21; an inverter circuit 9 generating an A.C. voltage by oscillation control when the voltage of an oscillation control terminal is set above 11 V to apply the A.C. voltage to the resonance circuit; and a voltage varying circuit 30 for keeping the voltage of the oscillation control terminal above 11 V when a voltage of 280 V in a normal time is input to the inverter circuit 9, and for lowering the voltage of the oscillation control terminal to stop the oscillation operation of the inverter circuit 9 when a D.C. voltage of 30 V due to influence of a leakage current is input to the inverter circuit 9. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a bulb-type fluorescent lamp and a lighting device, and more particularly to a technique for ensuring a preheating time of an electrode in a lighting circuit.

  In a lighting circuit for a bulb-type fluorescent lamp, a type that uses a PTC thermistor to set the electrode preheating time at the start of lighting is widely used. The disadvantage of this type is that the preheating time may be insufficient depending on the initial temperature of the PTC thermistor. For example, there is a state in which the electrode is at a low temperature but the PTC thermistor is still at a high temperature for a predetermined period after the lamp is turned off. If the lamp is turned on again in such a state, the electrode preheating is insufficient and the life of the electrode is shortened. Accordingly, a fluorescent lamp lighting circuit of a type in which the PTC thermistor is eliminated and the preheating time is fixed is proposed.

FIG. 12 is a circuit diagram showing a lighting circuit of the light bulb shaped fluorescent lamp disclosed in Non-Patent Document 1.
The lighting circuit of the bulb-type fluorescent lamp includes a DC power supply circuit 1, a drive circuit 2 and a load circuit 3. Since the DC power supply circuit 1 and the load circuit 3 have general specifications, description thereof is omitted. The drive circuit 2 includes an inverter circuit 9 (Phillips, UBA2024) as a main component. The inverter circuit 9 includes voltage-controlled switching elements 10 </ b> A and 10 </ b> B and an oscillation control circuit 11. The oscillation control circuit 11 applies voltages to the control terminals of the switching elements 10A and 10B so that the switching elements 10A and 10B are alternately turned on and off. When the switching elements 10 </ b> A and 10 </ b> B are alternately turned on and off, an AC voltage is applied to the load circuit 3 via the terminal 5 of the inverter circuit 9. The frequency of the AC voltage is determined by the resistance element 12 and the capacitors 13 and 15 connected to the inverter circuit 9.

Further, according to such a circuit configuration, since the preheating time is determined by the capacity of the capacitor 15, the preheating time can be fixedly set.
Philips, UBA2024; Half-bridge power IC for CFL lamps, data sheet Fig. 5, February 3, 2004

However, the lighting circuit of the light bulb-type fluorescent lamp according to Non-Patent Document 1 has the following problems when connected to a commercial power source through an automatic lighting device such as a human sensor.
When the automatic lighting device is in a cut-off state, a leakage current flows from the automatic lighting device to the lighting circuit. When a leakage current flows into the lighting circuit, a voltage lower than normal is generated at the output of the DC power supply circuit 1. With this voltage, the terminal 7 of the inverter circuit 9 reaches the operating voltage, the oscillation control circuit 11 starts oscillation control, and the inverter circuit 9 starts to oscillate. When an AC voltage is applied from the inverter circuit 9 to the load circuit 3 due to this oscillation, the voltage of the DC power supply circuit 1 decreases and the voltage of the terminal 7 of the inverter circuit 9 also decreases, so that the oscillation stops. That is, the above-described malfunction of oscillation / stop is repeated due to the influence of leakage current.

  Here, when the automatic lighting device is energized and the power is turned on while the inverter circuit 9 is oscillating erroneously due to the influence of the leakage current, the preheating time is set by the amount already started to oscillate. The problem of being shorter than the value arises. If the preheating time is shorter than the set value, the fluorescent tube is turned on in a state where the preheating is insufficient, and the life of the bulb-type fluorescent lamp is shortened by applying a load to the electrodes.

  The present invention has been made in view of the above problems, and provides a bulb-type fluorescent lamp and an illumination device that can ensure a predetermined preheating time even when connected to an automatic lighting device. For the purpose.

  The bulb-type fluorescent lamp according to the present invention can control switching between the start and stop of the oscillation operation by changing the voltage state of the input terminal to which the drive voltage is supplied, the output terminal for generating the oscillation output, and the voltage state. When the oscillation control terminal is in a high resistance state between the oscillation control terminal and the signal ground and the oscillation control terminal is at a voltage higher than the first oscillation control voltage, the oscillation operation is started and the oscillation is started. When the control terminal and the signal ground are in a high resistance state and the oscillation control terminal is a voltage equal to or lower than the second oscillation control voltage lower than the first oscillation control voltage, and between the oscillation control terminal and the signal ground When in the low resistance state, the inverter circuit that stops the oscillation operation, the fluorescent tube, and the output terminal are connected, and resonates with the oscillation output of the inverter circuit to the fluorescent tube A resonance circuit that supplies a flowing high voltage and a drive voltage supplied to the input terminal are monitored, and an oscillation control terminal is provided when a drive voltage that is lower than a threshold voltage lower than that during normal lighting is supplied to the input terminal. A low resistance state between the signal ground and a high resistance between the oscillation control terminal and the signal ground when a drive voltage higher than the threshold voltage is supplied to the input terminal; And a voltage variable circuit that changes the state of the voltage.

  The illumination device according to the present invention includes the light bulb shaped fluorescent lamp according to the present invention as a light source.

Since the configuration described in the means for solving the problem includes a voltage variable circuit, even if a leakage current or a minute current flows, the inverter circuit does not malfunction and the oscillation is stopped. Maintained. Therefore, no matter what timing the automatic lighting device is energized, the oscillation operation is started as usual, so that a predetermined preheating time is secured.
Moreover, even if it is a case where it connects with the apparatus which produces leakage current, a micro electric current, etc., such as an automatic lighting apparatus and a firefly switch, predetermined | prescribed preheating time can be ensured.

  The bulb-type fluorescent lamp further includes a time constant circuit in which a resistor and a capacitor are connected in series, a switch element, and switch control means for controlling the switch element, and the inverter circuit includes the time constant. Charge is accumulated in the capacitor of the circuit via the resistor, and if the accumulated amount of charge reaches a predetermined amount, the capacitor is discharged without passing through the resistor, and the charge is accumulated and discharged according to the cycle of accumulation. The switch element oscillates at a predetermined frequency, and the switch element has a first period corresponding to a first frequency in which the charge accumulation and discharge period is higher than a maximum frequency of a frequency band in which the fluorescent tube starts discharge. And the second constant corresponding to the second frequency lower than the highest frequency of the frequency band in which the fluorescent tube starts discharging, the time constant circuit The resistance value of the resistor to be turned is switched to one of a first resistance value corresponding to the first cycle and a second resistance value corresponding to the second cycle, and the switch control means includes: The switch element is switched so that the resistance value of the resistor becomes the first resistance value until a predetermined time elapses after the voltage of the oscillation control terminal starts to rise from about 0 V. If the predetermined time elapses, The switching element is switched so that the resistance value of the resistor becomes the second resistance value, and the voltage variable circuit is configured to oscillate when a driving voltage lower than the threshold voltage is supplied to the input terminal. It is desirable that the signal ground is in a low resistance state, and the voltage of the oscillation control terminal is set to approximately 0V.

  According to the above configuration, since the fluorescent tube is turned on when the frequency of the AC voltage changes from the first frequency to the second frequency, the predetermined time corresponds to the preheating time. Further, since the impedance of the resonance circuit is determined according to the frequency of the AC voltage, the magnitude of the preheating current flowing through the resonance circuit is also determined according to the frequency of the AC voltage. That is, a constant current corresponding to the first frequency flows as a preheating current in the resonance circuit. Then, by setting the first frequency so that a large current flows in advance, a large current can flow through the resonance circuit immediately after the start of preheating. Therefore, the preheating time can be shortened as compared with the prior art.

  The time constant of the time constant circuit can be changed not only by changing the resistance value of the resistor, but also generally by changing the capacitance value of the capacitor. However, when the capacitance value is changed in the light bulb-type fluorescent lamp using the inverter circuit having the specifications according to the present invention, there is a problem that the number of parts of the circuit for controlling the switch element is larger than when the resistance value is changed. That is, since a current in the reverse direction flows between the charge accumulation period and the discharge period, the capacitor needs a switch element that can flow a current in either direction. In this case, if the switch element is formed of a transistor, two transistors and two transistor protection diodes are required. On the other hand, since a current flows through the resistor during the accumulation period but does not flow during the discharge period, a switch element capable of flowing a current in one direction is sufficient. In this case, if the switch element is constituted by a transistor, one transistor is sufficient.

  In particular, in the light bulb-type fluorescent lamp, it is desired that the resin case that houses the lighting circuit is as small as possible in view of aesthetics and light distribution characteristics. Therefore, the number of parts of the circuit that controls the switch element is an important factor in the design of the lighting circuit. According to the present invention, since the resistance value of the time constant circuit is changed, the number of parts of the circuit for controlling the switch element can be reduced as compared with the case where the capacitance value is changed, and the bulb shape having excellent aesthetics and light distribution characteristics. A fluorescent lamp can be realized.

The frequency band at which the fluorescent tube starts discharging is the frequency of the alternating voltage at which the voltage applied to the fluorescent tube is higher than the discharge starting voltage of the fluorescent tube when the inverter circuit applies an AC voltage to the resonant circuit. Say obi.
Another bulb-type fluorescent lamp according to the present invention includes an input terminal to which a driving voltage is supplied, an output terminal for generating an oscillation output, and a frequency control terminal capable of changing an oscillation frequency by changing a voltage state. When the frequency control terminal and the signal ground are in a high resistance state and oscillate at a frequency corresponding to the voltage of the frequency control terminal, and the frequency control terminal and the signal ground are in a low resistance state. In addition, the inverter circuit that maintains the oscillation operation at the frequency f1 at the start of oscillation or repeats the oscillation operation and oscillation stop at the frequency f1, the fluorescent tube, and the output terminal are connected, and the oscillation of the inverter circuit A resonance circuit that resonates with the output and supplies an AC high voltage to the fluorescent tube, and a drive voltage supplied to the input terminal are monitored. When a driving voltage lower than the threshold voltage lower than the lighting voltage is supplied, the frequency control terminal and the signal ground are brought into a low resistance state, and a driving voltage higher than the threshold driving voltage is supplied to the input terminal. And a voltage variable circuit that changes a voltage state of the frequency control terminal by setting a high resistance state between the frequency control terminal and the signal ground.

  In the above configuration, since the voltage variable circuit is provided, when a leakage current, a minute current, or the like flows, the voltage of the frequency control terminal of the inverter circuit is set to approximately 0 V, and the oscillation frequency of the inverter circuit is set at the time of oscillation start. Maintaining at frequency. Therefore, when the automatic lighting device is energized, it is configured to oscillate from the set oscillation start frequency, so that a predetermined preheating time is secured.

Hereinafter, a bulb-type fluorescent lamp according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram illustrating a configuration of the lighting apparatus according to the present embodiment.
Illumination device 200 is a downlight embedded in, for example, a ceiling, and has a main body part 201 whose inner surface is a reflecting mirror that reflects light, a socket 202 attached to the inside of main body part 201, and attached to the socket 202. And a light bulb shaped fluorescent lamp 100.

FIG. 2 is a schematic diagram showing the configuration of the bulb-type fluorescent lamp according to the present embodiment.
The light bulb-type fluorescent lamp 100 is a substitute for a general light bulb 60 W, and includes a lighting circuit 101, a resin case 102, a light-transmitting globe 103, a base 104, and a fluorescent tube 21. In the bulb-type fluorescent lamp 100, the lighting circuit 101 is accommodated in the resin case 102. A base (E17 type) 104 is attached to one end of the resin case 102, a fluorescent tube 21 is disposed in the opposite direction of the base 104, and a light-transmitting globe 103 is disposed so as to cover the fluorescent tube 21.

Hereinafter, each embodiment of the lighting circuit 101 will be described.
<First Embodiment>
[Constitution]
FIG. 3 is a circuit diagram showing a configuration of the lighting circuit according to the first embodiment.
As shown in FIG. 3, the lighting circuit according to the first embodiment includes a DC power supply circuit 1, a drive circuit 2, a load circuit 3, and a voltage variable circuit 30.

The DC power supply circuit 1 receives an AC voltage from the commercial AC power supply 4 via the automatic lighting device 40, rectifies and smoothes it with the diodes 6 A and 6 B and the capacitors 7 A and 7 B via the resistance element 5, and passes through the noise filter 8. Output a DC voltage.
The load circuit 3 includes a series connection body of capacitors 17A and 17B for cutting a direct current component, and a resonance circuit in which a capacitor 18 and an inductor 19 are connected in series to a pair of electrodes 22A and 22B of the fluorescent tube 21. The series connection body of the capacitors 17 </ b> A and 17 </ b> B is connected between the positive and ground outputs of the DC power supply circuit 1. The resonance circuit is connected between the connection point of the capacitors 17A and 17B and the terminal 5 of the inverter circuit 9 which is the output terminal of the drive circuit 2. The fluorescent tube 21 is connected in parallel with the capacitor 18.

  The drive circuit 2 includes an inverter circuit 9 (Philips, UBA2024: Half-bridge power IC for CFL lamp) as a main component. The inverter circuit 9 includes a series connection body of voltage-controlled switching elements 10A and 10B, and an oscillation control circuit 11 that generates a control voltage for alternately turning on and off the switching elements 10A and 10B at the control terminals of the switching elements 10A and 10B. Is provided. The inverter circuit 9 is integrated in a package having eight terminals, and the drive circuit 2 can be miniaturized.

  Terminal 1 is a frequency control terminal that can control the oscillation frequency by changing the voltage state, terminal 2 is signal ground, terminal 4 is power ground, terminal 5 is an output terminal that generates oscillation output, and terminal 6 is drive voltage. And an input terminal to which a DC voltage is supplied, and a terminal 7 is an oscillation control terminal capable of controlling start / stop switching of the oscillation operation by changing the voltage state.

A positive electrode of the DC power supply circuit 1 is connected to the terminal 6 of the inverter circuit 9, and a ground electrode of the DC power supply circuit 1 is connected to the terminal 4.
Inside the inverter circuit 9, the switching element 10 </ b> A has a drain terminal connected to the terminal 6 and a source terminal connected to the terminal 5. The switching element 10 </ b> B has a drain terminal connected to the terminal 5 and a source terminal connected to the terminal 4. The oscillation control circuit 11 is connected to the terminals 6 and 4.

The resistor element 12 and the capacitor 13 constitute a series circuit, the resistor element 12 is connected between the terminal 7 and the terminal 8 of the inverter circuit 9, and the capacitor 13 is connected between the terminal 8 and the terminal 2 of the inverter circuit 9. Has been.
The capacitor 14 serves to charge the operating power supply voltage of the inverter circuit 9, one end of which is connected to the terminal 7 of the inverter circuit 9 and the other end is connected to the terminal 2 of the inverter circuit 9. The terminal 4 and the terminal 2 of the inverter circuit 9 are connected outside the inverter circuit 9.

The capacitor 15 serves to soft-start the fluorescent tube 21, one end of which is connected to the oscillation control circuit 11 via the terminal 1 of the inverter circuit 9 and the other end is connected to the terminal 2 of the inverter circuit 9.
The capacitor 16 plays a role of charging a power supply voltage for driving the switching element 10 </ b> A, and is connected between the terminal 3 and the terminal 5 of the inverter circuit 9.

The capacitor 20 plays a role of reducing the switching loss of the switching elements 10 </ b> A and 10 </ b> B, and is connected between the terminal 5 and the terminal 4 of the inverter circuit 9.
The voltage variable circuit 30 is connected to the terminal 6 of the inverter circuit 9 that is the positive side of the DC power supply circuit 1, the terminal 2 of the inverter circuit 9 that is the ground side of the DC power supply circuit 1, and the terminal 7 of the inverter circuit 9. Yes. One end of the resistance element 31 is connected to the terminal 6 of the inverter circuit 9, and the other end is connected to a connection point between the resistance element 32 and the resistance element 34. The other end of the resistance element 34 is connected to a connection point between the collector of the transistor 36 and the base of the transistor 37. The other end of the resistance element 32 is connected to a connection point between the base of the transistor 36 and the resistance element 33. The other end of the resistance element 33, the emitter of the transistor 36, and the emitter of the transistor 37 are connected to the terminal 2 of the inverter circuit 9. The collector of the transistor 37 is connected to the terminal 7 of the inverter circuit 9. The transistor 36 and the transistor 37 are housed in one package 35 and are downsized.

[Normal lighting operation]
Next, a normal lighting operation by the lighting circuit, in particular, the DC power supply circuit 1, the drive circuit 2, and the load circuit 3 will be described. For ease of explanation, the operation of the voltage variable circuit 30 will be described later as an operation when a leakage current occurs. The normal lighting operation is performed when the transistor 37 of the voltage variable circuit 30 is in an off state and the terminal 7 and the terminal 2 are in a high resistance state.

  The operation of the DC power supply circuit 1 is omitted because it is a known voltage doubler rectification smoothing method. When the voltage effective value of the commercial AC power supply 4 is 100V, the DC output voltage of the DC power supply circuit 1 is approximately 100V × 2 × 1.4 = 280V. When the automatic lighting device 40 is energized, the DC voltage (drive voltage) of 280 V is supplied from the DC power supply circuit 1 to the terminal 6 of the inverter circuit 9. The oscillation control circuit 11 inside the inverter circuit 9 has a regulator function for stepping down the DC voltage supplied to the terminal 6 and outputs a DC voltage of about 12 V to the terminal 7. This voltage is charged in the capacitor 14 in about several ms, and the oscillation control circuit 11 starts oscillation control when the voltage at the terminal 7 is charged and reaches 11V. When the inverter circuit 9 is oscillating, if the voltage at the terminal 7 decreases to 8.5 V or less, the oscillating operation of the inverter circuit 9 is stopped. In this sense, it can be said that the terminal 7 of the inverter circuit 9 is an oscillation control terminal that can control the start / stop switching of the oscillation operation by changing the voltage state.

In the inverter circuit 9, when the transistor 37 is in an ON state and the state between the terminal 7 and the terminal 2 is in a low resistance state, the voltage at the terminal 7 does not reach 11 V, so the inverter circuit 9 stops the oscillation operation.
Further, the inverter circuit 9 is configured such that when the transistor 37 is in an off state and the terminal 7 and the terminal 2 are in a high resistance state and a DC voltage of 60 V (the threshold voltage) or more is supplied to the terminal 6, the voltage at the terminal 7 Oscillates when the voltage reaches 11V or higher. Further, when the voltage supplied to the terminal 6 becomes less than 60V (the threshold voltage) while the inverter circuit 9 is oscillating, the voltage at the terminal 7 is lowered to 8.5V or less and the inverter circuit 9 oscillates. Stop operation.

  Here, the threshold voltage is set to 60 V. However, the threshold voltage is not limited to 60 V, and in this embodiment, the threshold voltage operates normally within a setting range of at least 30 to 100 V. Also, the threshold voltage setting range varies depending on the characteristics of the connected equipment and DC power supply circuit, etc., and the flow rate of leakage current and minute current due to the connected automatic lighting device and firefly switch, etc., and the driving voltage during normal lighting It depends on the fluctuation situation. For example, the threshold voltage must be lower than the lowest voltage during normal lighting (from start to turn-off). More specifically, the threshold voltage needs to be lower than the ripple voltage at the terminal 6 at the time of starting. In the configuration of the present embodiment, this ripple voltage is a little over 100V and less than 100V. Therefore, the upper limit of the threshold voltage is set to 100V. In addition, the threshold voltage is preferably higher than the maximum voltage generated at the terminal 6 due to leakage current, minute current, or the like when the transistor 37 is on and the resistance between the terminal 7 and the terminal 2 is low. In this configuration, the maximum voltage is a little less than 30V and does not exceed 30V. Therefore, it is recommended that the lower limit of the threshold voltage be 30V. However, even if the threshold voltage is set to be lower than 30V, it may be possible to operate normally. Further, in the present embodiment, the threshold voltage has no hysteresis, and when the voltage near the threshold voltage is continuously supplied to the terminal 6, the oscillation operation is frequently started and stopped. However, if the threshold voltage is set appropriately, such a state is not substantially obtained, and even if such a state is obtained, there is no particular problem in practical use. However, the threshold voltage may be configured to wait for hysteresis for various reasons such as preventing such a situation from occurring and ensuring stable operation. Even if such a configuration is adopted, the essence of the present invention does not change, so it can be said that they are substantially the same invention and are within the scope of the present invention.

FIG. 4 is a timing chart showing how the inverter circuit 9 oscillates.
4A shows the voltage at the terminal 8 of the inverter circuit 9, FIG. 4B shows the gate voltage of the switching element 10A, FIG. 4C shows the gate voltage of the switching element 10B, and FIG. The voltage of the terminal 5 is shown.
The inverter circuit 9 applies a constant voltage 12 V to the terminal 7 to charge the capacitor 13 via the resistance element 12 and detects the voltage at the terminal 8 as the charging voltage of the capacitor 13. In the present specification, unless otherwise specified, the voltage means a voltage viewed from the ground side voltage that is the terminal 4 and the terminal 2 of the inverter circuit 9. When the charging voltage of the capacitor 13 becomes a voltage corresponding to the voltage of the terminal 1, the electric charge of the capacitor 13 is instantaneously discharged via the terminal 8. The inverter circuit 9 repeats this operation. As a result, the voltage waveform at the terminal 8 of the inverter circuit 9 oscillates with a sawtooth wave due to CR oscillation as shown in FIG.

As shown in FIGS. 4B and 4C, the inverter circuit 9 generates a voltage waveform to be applied between the gate and source terminals of the switching elements 10 </ b> A and 10 </ b> B based on the sawtooth wave generated at the terminal 8.
Then, as shown in FIG. 4D, the voltage at the terminal 5 of the inverter circuit 9 shows a substantially rectangular wave voltage waveform.

The AC voltage at the terminal 5 of the inverter circuit 9 is applied to a resonance circuit including the capacitor 18 and the inductor 19 of the load circuit 3 to generate a resonance current. The resonance circuit resonates with the oscillation output from the terminal 5 that is the output terminal of the inverter circuit 9, and supplies an alternating high voltage between the electrodes 22 </ b> A and 22 </ b> B of the fluorescent tube 21.
Capacitors 17A and 17B prevent DC current from flowing from DC power supply circuit 1 to load circuit 3, and reduce leakage of high-frequency current flowing through load circuit 3 to commercial AC power supply 4 in cooperation with noise filter 8. It has a function. Since these capacitance values are sufficiently larger than those of the capacitor 18, the resonance frequency of the load circuit 3 is substantially determined by the values of the capacitor 18 and the inductor 19.

FIG. 5 is a timing chart showing the operation of the lighting circuit according to the first embodiment.
5A is the voltage at the terminal 7 of the inverter circuit 9, FIG. 5B is the voltage at the terminal 1 of the inverter circuit 9, FIG. 5C is the frequency of the AC voltage generated at the terminal 5 of the inverter circuit 9, FIG. 5D shows the current flowing through the electrodes 22A and 22B of the fluorescent tube 21. FIG.
As shown in FIG. 5A, the voltage at the terminal 7 rises from 0V to 12V after the power is turned on with the capacitor 14 being charged.

Charging of the capacitor 15 is started from time t1 when the voltage at the terminal 7 reaches 11V. Therefore, as shown in FIG. 5B, the voltage at the terminal 1 starts to rise from time t1.
As shown in FIG. 5 (c), the frequency of the alternating voltage generated at the terminal 5 of the inverter circuit 9 is the frequency f1 at time t1, and decreases linearly as the voltage at the terminal 1 increases. The frequency f2 is reached at time t2 when the voltage of 1 reaches 4V. After the time t2, the frequency f2 is maintained. Here, based on the specification of the inverter circuit 9, the frequency f1 is 2.5 times the frequency f2 when the fluorescent tube 21 is stably lit. The frequency f2 is set by f2 = 1 / (1.1 × capacitance value of the capacitor 13 × resistance value of the resistance element 12). Since the resonance frequency f0 of the load circuit 3 is set to be between the frequencies f1 and f2, a resonance voltage sufficient to cause the capacitor 18 to start the fluorescent tube 21 while the frequency decreases from f1 to f2. Will occur. As a result, the fluorescent tube 21 is turned on at time t0.

As shown in FIG. 5 (d), the currents flowing through the electrodes 22A and 22B gradually increase exponentially from time t1 to time t0, decrease with the lighting of the fluorescent tube 21 at time t0, and thereafter. Is almost constant. The time from time t1 to time t0 corresponds to the preheating time.
As shown in FIG. 5B, when the drive voltage is supplied to the terminal 6, the terminal 1 of the inverter circuit becomes 11V, and the voltage rises from about 0V. Then, as shown in FIG. 5C, the inverter circuit 9 oscillates by changing the frequency according to the voltage rise at the terminal 1. That is, the terminal 1 of the inverter circuit 9 can be said to be a frequency control terminal that controls the oscillation frequency of the inverter circuit 9.

[Operation of variable voltage circuit]
Next, the operation of the voltage variable circuit 30 will be described with reference to FIG.
When the automatic lighting device 40 is in a cut-off state and a leakage current flows out from the automatic lighting device 40 to the DC power supply circuit 1, when the effective voltage value of the commercial AC power supply 4 is 100 V, the direct current from the DC power supply circuit 1 during normal lighting is used. A DC voltage lower than the voltage 280 V, for example 30 V, is applied to the terminal 6 of the inverter circuit 9.

  The direct current voltage 30 V due to the influence of the leakage current is divided by the resistance elements 31, 32 and 33 and applied between the emitter and base of the transistor 36. When the resistance value of the resistance element 31 is set to 470 kΩ, the resistance value of the resistance element 32 is set to 820 kΩ, the resistance value of the resistance element 33 is set to 15 kΩ, and the resistance value of the resistance element 34 is set to 560 kΩ, the resistance element 31, the resistance element 32, and the resistance element 34 are set. The voltage at the connection point is about 12V with a divided voltage of 0.41. Further, the base voltage of the transistor 36 becomes about 0.2 V due to the voltage division of 0.018 between the resistance element 32 and the resistance element 33. Since the transistor 36 is turned on when the emitter-base voltage becomes 0.6 V or higher, the transistor 36 is turned off when leakage current flows. Then, a current flows into the base of the transistor 37 through the resistance element 34, and the transistor 37 is turned on. When the transistor 37 is turned on, the resistance between the terminal 7 and the terminal 2 of the inverter circuit 9 becomes low.

As a result, the voltage variable circuit 30 reduces the voltage at the terminal 7 of the inverter circuit 9 to approximately 0 V, and the inverter circuit 9 maintains the stopped state without oscillating.
On the other hand, when the automatic lighting device 40 is in an energized state, a normal DC voltage 280 V is supplied from the DC power supply circuit 1 to the terminal 6 of the inverter circuit 9. The voltage at the connection point of the resistive element 31, the resistive element 32, and the resistive element 34 of the voltage variable circuit 30 is about 115V with a divided voltage of 0.41. Further, a voltage of about 2 V is applied between the emitter and base of the transistor 36 by the voltage division of 0.018 between the resistance element 32 and the resistance element 33. Thus, when the transistor 36 is turned on, the base voltage of the transistor 37 becomes 0 V, so that the transistor 37 is turned off. When the transistor 37 is turned off, the resistance between the terminal 7 and the terminal 2 of the inverter circuit 9 becomes high.

Therefore, in this case, the voltage variable circuit 30 keeps the voltage of the terminal 7 of the inverter circuit 9 without being lowered, and the inverter circuit 9 generates an alternating voltage by a normal oscillation operation, and the electrode 22A is generated in a predetermined preheating time. 22B are preheated and the fluorescent tube 21 is lit.
When the resistance elements 31 to 34 have the above-described resistance values, the voltage applied between the emitter and base of the transistor 36 is 0.6 V when the voltage supplied to the terminal 6 is about 60 V (the threshold voltage) or more. Thus, the transistor 36 is turned on.

That is, the voltage variable circuit 30 monitors the drive voltage supplied to the terminal 6 and turns on the transistor 37 when a DC voltage less than about 60 V (the threshold voltage), which is lower than that during normal lighting, is supplied to the terminal 6. By setting the state between the terminal 7 and the terminal 2 of the inverter circuit 9 to be in a low resistance state, the voltage at the terminal 7 is set to approximately 0 V, and the oscillation operation of the inverter circuit 9 is stopped.
The voltage variable circuit 30 monitors the drive voltage supplied to the terminal 6, and when a DC voltage of about 60 V (the threshold voltage) or more is supplied to the terminal 6, the transistor 37 is turned off to turn the inverter circuit 9, the oscillation operation of the inverter circuit 9 is maintained without lowering the voltage of the terminal 7 by setting the terminal 7 to the terminal 2 in a high resistance state.

  When the lighting circuit does not include the voltage variable circuit 30, when a leakage current flows from the automatic lighting device 40, the inverter circuit 9 may cause an oscillation / stop error as described in the column of the problem to be solved by the invention. Repeat operation. Here, when the automatic lighting device is energized and a normal voltage is applied from the DC power supply circuit 1 to the inverter circuit 9 while the inverter circuit 9 is oscillating due to a malfunction, the oscillation circuit has already started to oscillate. The preheating time will be shorter than the set value.

  On the other hand, since the lighting circuit according to the first embodiment includes the voltage variable circuit 30, even if a leakage current flows, no malfunction occurs in the inverter circuit 9, and oscillation occurs. The stopped state can be maintained. Therefore, no matter what timing the automatic lighting device 40 is energized, the oscillation control is started as usual, so a predetermined preheating time is secured.

  Since the voltage supplied to the terminal 6 of the inverter circuit 9 is assumed to be up to about 50 V due to the influence of the leakage current, the transistor 36 is turned on when the voltage of the DC power supply circuit 1 is in the range of 50 V or less. The resistance values of the resistance elements 31 to 34 are selected so that the voltage between the emitter and the base of the transistor 36 is less than the operating voltage of 0.6 V in the off state.

<Second Embodiment>
Next, a lighting circuit according to a second embodiment will be described.
[Constitution]
FIG. 6 is a circuit diagram showing a configuration of a lighting circuit according to the second embodiment. Since the configurations of the DC power supply circuit 1, the load circuit 3, and the voltage variable circuit 30 are the same as those in the first embodiment, the description thereof is omitted here, and the configuration of the drive circuit 2 that is different from the first embodiment. In the lighting circuit according to the second embodiment, in the drive circuit 2, the series connection body of the PNP bipolar transistor 23 and the resistance element 24 is connected in parallel to the resistance element 12. Further, a resistance element 25 is connected between the emitter and base of the transistor 23, and a resistance element 26 and a capacitor 27 are connected between the base of the transistor 23 and the terminal 2 of the inverter circuit 9. The resistance elements 25 and 26 and the capacitor 27 turn on the transistor 23 until a predetermined time elapses after the voltage at the terminal 7 of the inverter circuit 9 starts to rise from approximately 0 V. Turn off.

[Lighting operation]
Next, a normal lighting operation by the lighting circuit, in particular, the DC power supply circuit 1, the drive circuit 2, and the load circuit 3 will be described. For ease of explanation, the operation of the voltage variable circuit 30 will be described later as an operation when a leakage current occurs.
FIG. 7 is a timing chart showing the operation of the lighting circuit according to the second embodiment.

FIG. 7A shows the voltage at the terminal 7 of the inverter circuit 9. The voltage at the terminal 7 rises from 0V to 12V after the commercial AC power supply 4 is turned on.
FIG. 7B shows the voltage at the terminal 1 of the inverter circuit 9. The inverter circuit 9 starts charging the capacitor 15 at time t1 when the voltage at the terminal 7 reaches 11V. Therefore, the voltage at terminal 1 starts to rise from time t1. The time from turning on the commercial AC power supply 4 to time 1 is several ms. The time from the time t1 until the voltage at the terminal 1 reaches 12V is set to be 0.1 second or less. This time is determined by the capacitance of the capacitor 15.

FIG. 7C shows the state of the transistor 23. The transistor 23 is turned on when the emitter-base voltage exceeds −0.6 V in the negative direction, and is turned off when the voltage does not exceed −0.6 V. The voltage between the emitter and the base is induced by a current flowing through the resistance element 25.
The voltage at the terminal 7 increases from 0V to 12V after the commercial AC power supply 4 is turned on. Immediately after the commercial AC power supply 4 is turned on, the capacitor 27 is hardly charged, so that a charging current for charging the capacitor 27 flows through the resistance element 25. Therefore, a negative voltage of the resistance element 25 obtained by dividing the voltage of the terminal 7 by the resistance elements 25 and 26 is applied between the emitter and base of the transistor 23. Since the resistance ratio of the resistance elements 25 and 26 is about 1: 5, the emitter-base voltage is about -2V. Actually, current flows from the emitter of the transistor 23 to the resistance element 26 and the capacitor 27 through the base, and the base voltage viewed from the emitter becomes about −0.6 V, which is the forward voltage of the NP junction, and is kept on. As a result, the transistor 23 is turned on.

  Thereafter, as time elapses, the capacitor 27 is charged. When the charging voltage of the capacitor 13 reaches 8.4 V at time t4, the voltage sum applied to the resistance elements 25 and 26 becomes 3.6 V. At this time, the voltage between the emitter and the base of the transistor 23 is divided by the resistance elements 25 and 26 and becomes a voltage that does not exceed −0.6 V in the negative direction, and the transistor 23 cannot pass the base current and is turned off. Transition to the state. Then, it is completely turned off at time t2. The time constant of the CR circuit composed of the resistance elements 25 and 26 and the capacitor 27 is set to be 0.5 seconds to 1 second.

FIG. 7D shows the frequency of the AC voltage generated at the terminal 5 of the inverter circuit 9. When the transistor 23 is in the on state, the oscillation resistor is a parallel connection body of the resistance element 12 and the resistance element 24. On the other hand, when the transistor 23 is off, the oscillation resistor is the resistance element 12.
The frequency of the AC voltage is the frequency f1 at time t1, decreases as the voltage at the terminal 1 increases, and reaches the frequency f3 at time t3. The frequency f1 is higher than 2.5 times the stable frequency f2 in which the oscillation resistor is the parallel connection body of the resistance element 12 and the resistance element 24, and thus the oscillation resistor is the resistance element 12 only. The frequency f3 is set by f3 = 1 / (1.1 × capacitance value of the capacitor 13 × resistance value of the oscillation resistor). The frequency f3 is set to be lower than the frequency f1 and higher than the highest frequency in the frequency band where the fluorescent tube 21 starts discharging.

Since the transistor 23 shifts to the off state at time t4, the frequency of the AC voltage passes through the resonance frequency f0 at time t0 and decreases to the stable frequency f2.
FIG. 7E shows the current flowing through the electrodes 22 </ b> A and 22 </ b> B of the fluorescent tube 21. The magnitude of the preheating current in the preheating time is determined according to the frequency of the AC voltage. As the frequency approaches the resonance frequency f0 from time t1 to time t3, the preheating current increases. Since the frequency is constant at f3 from time t3 to t4, the preheating current is also substantially constant. Since the frequency f3 is higher than the highest frequency in the frequency band at which the fluorescent tube 21 starts discharging, the fluorescent tube 21 does not yet start discharging.

As the frequency approaches the resonant frequency f0 from time t4 to t0, the preheating current further increases. The fluorescent tube 21 starts discharging at the time when the fluorescent tube 21 reaches the highest frequency in the frequency band where the discharge starts (immediately before time t0 when the resonance frequency f0 is reached). Since the fluorescent tube 21 is in a lighting state after the discharge is started, the current flowing through the electrodes 22A and 22B becomes substantially constant.
As described above, the magnitude of the preheating current flowing through the electrodes 22A and 22B is determined according to the frequency of the AC voltage. By setting the frequency f3 so that a large preheating current flows in advance, it is possible to cause a large preheating current to flow immediately after the start of preheating. Further, the preheating time can be set to an appropriate time of 0.5 seconds to 1 second, for example, by changing the time constant of the resistance element 26 and the capacitor 27.

  Actually, the test was performed by setting the current of about 250 mA to flow through the electrodes 22A and 22B having a resistance of about 9Ω when the light was turned off for about 0.9 seconds. As a result, after preheating for 0.9 seconds, the resistance values of the electrodes 22A and 22B were increased to 30Ω or more, and the electrode temperature was 800 ° C or more. That is, it was confirmed that thermionic electrons can be emitted, and sputtering of the electrode at the moment when the fluorescent tube 21 is turned on can be prevented.

[Operation of variable voltage circuit]
Next, the operation of the voltage variable circuit 30 will be described with reference to FIG. Basically, the operation is the same as that described in the first embodiment.
When the automatic lighting device 40 is cut off and a leakage current flows into the lighting circuit, a DC voltage of about 30 V is applied to the terminal 6 of the inverter circuit 9, the transistor 36 is turned off, and the transistor 37 is turned on. Become. Therefore, the voltage at the terminal 7 of the inverter circuit 9 is maintained at approximately 0 V, and the capacitor 27 and the capacitor 13 are not charged.

  Here, when the automatic lighting device 40 is energized, a DC voltage of about 280 V is applied to the terminal 6 of the inverter circuit 9, the transistor 36 is turned on, and the transistor 37 is turned off. As a result, the voltage at the terminal 7 of the inverter circuit starts to rise from approximately 0 V, charging of the capacitor 27 and the capacitor 13 is started, and the above-described lighting operation is started.

  When the lighting circuit does not include the voltage variable circuit 30, when leakage current flows from the automatic lighting device 40, the voltage at the terminal 7 of the inverter circuit 9 rises and charging of the capacitor 27 and the capacitor 13 is started. Thus, when the automatic lighting device 40 is energized in this state, the preheating time is shortened by the amount already charged in the capacitor 27 and the capacitor 13.

  On the other hand, since the lighting circuit according to the second embodiment includes the voltage variable circuit 30, the voltage at the terminal 7 of the inverter circuit 9 is approximately 0 V even when leakage current flows. The capacitor 27 and the capacitor 13 are almost not charged. Therefore, a predetermined preheating time is ensured no matter what timing the automatic lighting device 40 is energized.

When a DC voltage of about 0 V to 60 V is applied to the terminal 6 of the inverter circuit 9 due to leakage current, the voltage at the terminal 7 of the inverter circuit 9 is maintained at 0.2 V or less, and the capacitor 27 and the capacitor 13 Was confirmed to be almost not charged.
<Third Embodiment>
Next, a lighting circuit according to a third embodiment will be described.

[Constitution]
FIG. 8 is a circuit diagram showing a configuration of a lighting circuit according to the third embodiment. The lighting circuit according to the third embodiment includes a DC power supply circuit 1, a drive circuit 2, a load circuit 3, and a voltage variable circuit 50. Since the configurations of the DC power supply circuit 1, the drive circuit 2, and the load circuit 3 are the same as those in the first embodiment, description thereof will be omitted and the configuration of the voltage variable circuit 50 will be described.

  The configuration of the voltage variable circuit 50 is the same as that of the voltage variable circuit 30 in the first embodiment, but in the first embodiment, the collector of the transistor 37 of the voltage variable circuit 30 is connected to the terminal 7 of the inverter circuit 9. The third embodiment is different from the first embodiment in that the collector of the transistor 37 of the voltage variable circuit 50 is connected to the terminal 1 of the inverter circuit 9 in the third embodiment.

[Operation of Voltage Variable Circuit 50]
Next, the operation of the lighting device according to the third embodiment will be described. Since the normal lighting operation by the DC power supply circuit 1, the drive circuit 2, and the load circuit 3 is the same as that of the first embodiment, a description thereof will be omitted. Here, the voltage variable circuit when a leakage current flows in is described. 50 operations will be described.

  When the automatic lighting device 40 is in a cut-off state, a leakage current flows from the automatic lighting device 40 into the lighting circuit, and when a DC voltage of about 30 V is supplied to the terminal 6 of the inverter circuit 9, the voltage variable circuit 50 includes the transistor 36. Is turned off, and the transistor 37 is turned on. As a result, the voltage at the terminal 1 of the inverter circuit 9 decreases, and the voltage at the terminal 1 is maintained at approximately 0V. Therefore, the inverter circuit 9 oscillates at the maximum frequency f1 at the start of oscillation shown in FIG. When an AC voltage is applied from the inverter circuit 9 to the load circuit 3 due to oscillation, the voltage of the DC power supply circuit 1 decreases and the voltage of the terminal 7 of the inverter circuit 9 also decreases, so the oscillation operation stops. When leakage current flows in this way, oscillation and stop are repeated at frequency f1.

  When the automatic lighting device 40 is energized at the timing of oscillating at the frequency f1, a DC voltage of 280 V is supplied to the terminal 6 of the inverter circuit 9, and in the voltage variable circuit 50, the transistor 36 is turned on. 37 is turned off. As a result, the state in which the voltage at the terminal 1 of the inverter circuit 9 is maintained at approximately 0V is released, and as shown in FIG. 5B, the voltage gradually increases from approximately 0V. As shown in (c), it starts to change from the frequency f1.

When the resistance elements 31 to 34 have the resistance values described in the first embodiment, when the voltage supplied to the terminal 6 is about 60 V or more, the base voltage of the transistor 36 is 0.6 V or more, The transistor 36 is turned on.
That is, the voltage variable circuit 50 monitors the drive voltage supplied to the terminal 6, and when the terminal 6 is supplied with a DC voltage less than about 60V lower than that during normal lighting, the transistor 37 is turned on and the inverter is turned on. By setting a low resistance state between the terminal 1 and the terminal 2 of the circuit 9, the voltage of the terminal 1 is set to approximately 0 V, and the frequency of the inverter circuit 9 is maintained at the frequency f1 at the start of oscillation.

The voltage variable circuit 50 monitors the drive voltage supplied to the terminal 6, and when a DC voltage of about 60 V or higher is supplied to the terminal 6, the transistor 37 is turned off to turn on the terminal 1 of the inverter circuit 9. -By making a high resistance state between the terminals 2, the oscillation frequency of the inverter circuit 9 is changed without affecting the voltage change of the terminal 1.
When the lighting circuit does not include the voltage variable circuit 50, when a leakage current flows from the automatic lighting device 40, the voltage at the terminal 1 of the inverter circuit 9 increases. As the voltage at the terminal 1 increases, the oscillation frequency gradually decreases from f1. When the automatic lighting device 40 is energized at this timing, the preheating time is shortened as much as the oscillation frequency is reduced.

  On the other hand, since the lighting circuit according to the third embodiment includes the voltage variable circuit 50, the voltage at the terminal 1 of the inverter circuit 9 is substantially 0 V even when leakage current flows. When the inverter circuit 9 is oscillating, it is maintained at the oscillation frequency f1 at the start of oscillation. Therefore, when the automatic lighting device 40 is energized, the set frequency at the start of oscillation is maintained. Since the configuration oscillates from f1, a predetermined preheating time is secured.

<Modification>
As described above, the present invention has been described based on the embodiments. However, the content of the present invention is not limited to the specific examples shown in the above-described embodiments. For example, the following modifications are possible. Can think.
(1) In the above, the load circuit 3 is a resonance circuit in which the capacitor 18 and the inductor 19 are connected in series to the series connection body of the capacitors 17A and 17B that cut the DC component, and the pair of electrodes 22A and 22B of the fluorescent tube 21. However, the present invention is not limited to this, and a configuration like the load circuit 60 shown in FIG. 9 may be used.

FIG. 9 is a circuit diagram illustrating a configuration of a lighting circuit according to a modification. The lighting circuit according to the modification is obtained by replacing the load circuit 3 with the load circuit 60 in the lighting circuit according to the second embodiment.
The load circuit 60 is wound with secondary windings 40 </ b> A and 40 </ b> B that are magnetically coupled to the inductor 19. Secondary windings 40A and 40B are connected to electrodes 22A and 22B via capacitors 41A and 41B, respectively. Capacitors 41A and 41B serve to limit the preheating current and prevent excessive current from flowing through the circuit when the electrodes 22A and 22B are short-circuited. The value of the current flowing through the electrodes 22A and 22B at the start of preheating can be freely set by the oscillation frequency, the number of turns of the secondary windings 40A and 40B, and the capacitors 41A and 41B.

FIG. 10 is a timing chart showing the operation of the lighting circuit according to the modification.
10A shows the voltage at the terminal 7 of the inverter circuit 9, FIG. 10B shows the voltage at the terminal 1 of the inverter circuit 9, FIG. 10C shows the state of the transistor 23, and FIG. The frequency of the alternating voltage generated at the terminal 5 of the inverter circuit 9, FIG. 10 (d) shows the current flowing through the electrodes 22A and 22B of the fluorescent tube 21. FIG.

The operations in FIGS. 10A to 10D are the same as those in FIGS. 7A to 7D described in the second embodiment, and a description thereof will be omitted here.
As shown in FIG. 10 (d), the oscillation frequency is substantially constant from time t3 to time t0. Therefore, the voltage of the inductor 19 is also constant, and the voltage applied to the electrodes 22A and 22B is also constant. Since the electrodes 22A and 22B are cold at time t3, the resistance value is small, and the resistance value increases with preheating. As shown in FIG. 4F, the current flowing through the electrodes 22A and 22B flows so that a large current flows immediately after the start of preheating and the current decreases with the progress of preheating. Since the current value flowing through the electrodes 22A and 22B at the start of preheating can be freely set by the oscillation frequency, the number of turns of the secondary windings 40A and 40B, and the capacitors 41A and 41B, the electrodes 22A and 22B when the fluorescent tube 21 is stably lit. Can be set to an appropriate value in consideration of the loss.

  Actually, the test was performed by setting so that a current having an effective voltage value of about 3.0 V was applied to the electrodes 22A and 22B having a resistance of about 9Ω when turned off for about 0.7 seconds. As a result, after preheating for 0.7 seconds, the resistance values of the electrodes 22A and 22B were increased to 30Ω or more, and the electrode temperature was 800 ° C or more. That is, it was confirmed that thermionic electrons can be emitted, and sputtering of the electrode at the moment when the fluorescent tube 21 is turned on can be prevented. Preheating time can be shortened by preheating the electrodes 22A and 22B with the secondary windings 40A and 40B.

  (2) In the second embodiment and the above-described modification, the transistor 23 may be a PNP bipolar transistor or a P-channel field effect transistor. By using a general-purpose switch element in this way, an increase in cost can be suppressed. In particular, when a bipolar transistor is used, the frequency of the AC voltage continuously changes from the first frequency to the second frequency because it passes through the unsaturated region when transitioning from the on state to the off state. Therefore, the fluorescent tube 21 can be soft-started, and the burden on the electrodes 22A and 22B can be suppressed.

  (3) FIG. 11 is a diagram illustrating a circuit configuration of the automatic lighting device 40. The automatic lighting device 40 includes a semiconductor switch element 41, a control circuit 42, a capacitive element 43, and an inductive element 44. The control circuit 42 is connected in parallel to the semiconductor switch element 41, and inductive elements are connected in series to the parallel connection body. And the capacitive element 43 is connected to this series connection body in parallel. The automatic lighting device 40 is connected to the commercial power supply 4 in series. Note that even when the automatic lighting device 40 is in a shut-off state, that is, when the semiconductor switch element 41 is in an off state, a leakage current may flow out from the capacitive element 43 or the control circuit 42.

In addition, the automatic lighting device 40 is not limited to such a configuration, and may be, for example, a type that is connected in parallel to a commercial power source.
Further, even when a firefly switch is connected instead of the automatic lighting device 40, malfunction of the inverter circuit can be prevented. Here, the firefly switch includes a neon lamp, and when the power switch is off, a minute current flows from the power source to the neon lamp through the light bulb shaped fluorescent lamp, and the neon lamp is lit.

  In such firefly lamps and the like, the malfunction of the inverter circuit caused by the minute current that lights the neon lamp or the like is prevented from malfunctioning of the inverter circuit caused by the leakage current flowing from the automatic lighting device 40 or the like. This can be prevented by a configuration similar to that of the lighting circuit.

  The present invention can be widely applied to a bulb-type fluorescent lamp and a lighting device. Moreover, since the present invention can provide a long-life bulb-type fluorescent lamp and lighting device by securing a predetermined preheating time, its industrial utility value is extremely high.

It is a schematic diagram which shows the structure of the illuminating device which concerns on this Embodiment. It is a schematic diagram which shows the structure of the lightbulb-type fluorescent lamp which concerns on this Embodiment. It is a circuit diagram which shows the structure of the lighting circuit which concerns on 1st Embodiment. It is a timing chart which shows the mode of oscillation. It is a timing chart which shows operation | movement of the lighting circuit which concerns on 1st Embodiment. It is a circuit diagram which shows the structure of the lighting circuit which concerns on 2nd Embodiment. It is a timing chart which shows operation | movement of the lighting circuit which concerns on 2nd Embodiment. It is a circuit diagram which shows the structure of the lighting circuit which concerns on 3rd Embodiment. It is a circuit diagram which shows the structure of the lighting circuit which concerns on a modification. It is a timing chart which shows operation | movement of the lighting circuit which concerns on a modification. It is a figure which shows the circuit structure of an automatic lighting apparatus. It is a circuit diagram which shows the lighting circuit of the lightbulb-type fluorescent lamp disclosed by the nonpatent literature 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 DC power supply circuit 2 Drive circuit 3 Load circuit 4 Commercial AC power supply 9 Inverter circuit 21 Fluorescent tube 30, 50 Voltage variable circuit 36, 37 Transistor 40 Automatic lighting device 100 Light bulb type fluorescent lamp 200 Illumination device

Claims (4)

Oscillation control having an input terminal to which drive voltage is supplied, an output terminal for generating oscillation output, and an oscillation control terminal capable of controlling start / stop of oscillation operation by changing the voltage state When the terminal-signal ground is in a high resistance state and the oscillation control terminal is at a voltage equal to or higher than the first oscillation control voltage, the oscillation operation is started and the resistance between the oscillation control terminal-signal ground is high. When the oscillation control terminal is in a state and has a voltage equal to or lower than the second oscillation control voltage lower than the first oscillation control voltage, and when the oscillation control terminal and the signal ground are in a low resistance state, oscillation occurs. An inverter circuit that stops operation;
A fluorescent tube;
A resonance circuit that is connected to the output terminal and resonates with an oscillation output of the inverter circuit to supply an AC high voltage to the fluorescent tube;
The drive voltage supplied to the input terminal is monitored, and when a drive voltage lower than the threshold voltage lower than that during normal lighting is supplied to the input terminal, the oscillation control terminal and the signal ground are brought into a low resistance state. And a voltage variable circuit that changes a voltage state of the oscillation control terminal by setting a high resistance state between the oscillation control terminal and the signal ground when a drive voltage higher than the threshold voltage is supplied to the input terminal. A bulb-type fluorescent lamp characterized by comprising: A time constant circuit in which a resistor and a capacitor are connected in series;
A switch element;
Switch control means for controlling the switch element,
The inverter circuit causes the capacitor of the time constant circuit to accumulate charge through the resistor, and causes the capacitor to discharge the charge without passing through the resistor when the amount of accumulated charge reaches a predetermined amount. Oscillates at a frequency corresponding to the period of accumulation and release of
The switch element has a first period corresponding to a first frequency in which the charge accumulation and discharge period is higher than a maximum frequency of a frequency band in which the fluorescent tube starts discharge, and the fluorescent tube discharges. The resistance value of the resistor included in the time constant circuit is set to the first period so as to be one of the second period corresponding to the second frequency lower than the highest frequency of the frequency band to be started. While switching to one of the corresponding first resistance value and the second resistance value corresponding to the second period,
The switch control means switches the switch element so that the resistance value of the resistor becomes a first resistance value until a predetermined time elapses after the voltage of the oscillation control terminal starts to increase from approximately 0 V, When the predetermined time elapses, the switch element is switched so that the resistance value of the resistor becomes the second resistance value, and
The voltage variable circuit sets a low resistance state between the oscillation control terminal and the signal ground when the drive voltage less than the threshold voltage is supplied to the input terminal, and sets the voltage of the oscillation control terminal to approximately 0V. The light bulb shaped fluorescent lamp according to claim 1. It has an input terminal to which a drive voltage is supplied, an output terminal that generates an oscillation output, and a frequency control terminal that can change the oscillation frequency by changing the voltage state. Between the frequency control terminal and the signal ground In the high resistance state, the oscillation operation is performed at a frequency according to the voltage of the frequency control terminal. When the frequency control terminal and the signal ground are in a low resistance state, the oscillation operation is performed at the frequency f1 at the start of oscillation. An inverter circuit for maintaining or repeating oscillation operation and oscillation stop at the frequency f1,
A fluorescent tube;
A resonance circuit that is connected to the output terminal and resonates with an oscillation output of the inverter circuit to supply an AC high voltage to the fluorescent tube;
The drive voltage supplied to the input terminal is monitored, and when a drive voltage lower than the threshold voltage lower than that during normal lighting is supplied to the input terminal, the frequency control terminal and the signal ground are brought into a low resistance state. In addition, when a drive voltage equal to or higher than the threshold drive voltage is supplied to the input terminal, the voltage variable that changes the voltage state of the frequency control terminal by setting a high resistance state between the frequency control terminal and the signal ground. A bulb-type fluorescent lamp comprising a circuit.   An illuminating device comprising the bulb-type fluorescent lamp according to any one of claims 1 to 3 as a light source.

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