JPH10191654A - Inverter circuit, and illumination device using the circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact, lightweight and inexpensive illumination device using a mobile inverter series circuit. SOLUTION: An electric-discharge lamp LMP and an inductor ID1 are connected in series between a connection point at which a PNP transistor Q1 and NPN transistor Q2 are connected in series between positive and negative terminals of a power source E. An emitter base of Q1, a Zener diode ZD1, a series circuit of a resistor R2 and a resistor R1 are connected in parallel between a collector of the NPN transistor Q3 in which an emitter is connected to a negative terminal of the power source and a positive terminal of the power source. Variable resistors VR1 and VR2 are connected between bases of Q2 and Q3 and the positive terminal of the power source, and variable capacitors VC1 and VC2 are connected between the collectors and the bases. Q1 and Q2 constitute a mobile inverter half bridge circuit, and an illumination device can be dimmed by the changes in the characteristics of VR1, VR2, VC1 and VC2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-running inverter / series circuit (half-bridge circuit, modified half-bridge circuit, full-bridge circuit, etc.) using a self-running multivibrator, and a discharge tube using the circuit. The present invention relates to a lighting device for lighting a lighting device. Although the circuit of the present invention uses a cold cathode discharge tube as a load for explanation, it can be applied to a hot cathode discharge tube by adding a high-pressure mercury lamp or a filament circuit, and can be applied to a device other than a discharge tube such as a motor. Applicable to loads.

[0002]

2. Description of the Related Art The illuminance required by a lighting device is not always constant, and varies depending on the surrounding illuminance, an object to be visually recognized, and the like. In addition, the brightness of the discharge tube during lighting varies depending on the ambient temperature. For example, if the ambient temperature becomes about -30 degrees Celsius, it becomes about 10% of that at room temperature. Therefore, in home lighting devices and backlight lighting devices for liquid crystal display devices using an inverter circuit, a circuit that manually adjusts light in accordance with the ambient temperature and illuminance is used. As an inverter circuit used for a lighting device, an inverter / one-piece circuit, an inverter / push-pull circuit, or an inverter / series circuit is widely used. A self-excited inverter / push-pull circuit or a self-excited inverter / series circuit has a smaller number of components than a separately-excited inverter / push-pull circuit or a separately-excited inverter / series circuit, and can be designed to be smaller, but uses a transformer for feedback. Therefore, the frequency is determined by the magnetic circuit, so that it was not possible to change the frequency and change the impedance of the inductor or capacitor, which is a load current control element (ballast), to perform dimming. . During operation of the inverter / push-type circuit and the inverter / push-pull circuit, a voltage twice as large as the power supply voltage is applied to the transistor in both the self-excited inverter circuit and the separately excited inverter circuit. Often used for. However, inverters and series circuits, in principle, do not apply a voltage higher than the power supply voltage to transistors in self-excited inverter circuits or separately-excited inverter circuits. There are many.

Conventionally used self-excited inverters and series circuits are often self-excited inverters and modified half-bridge circuits as shown in FIG. This circuit is a DC power supply E
A capacitor C7, a parallel circuit of a discharge tube LMP and a capacitor C8 as a load, and a load current between a connection point of two NPN transistors Q12 and Q13 connected in series between the positive and negative terminals of the DC power supply E and the positive terminal of the DC power source E. Inductor ID2 as a control element, transformer TR2 1 using a saturable iron core
The coil L3, which is the next winding, is connected in series in the order described,
A coil L4 which is one feedback winding of TR2 is connected to a resistor R1.
6 to the base and emitter of Q12 and TR2
The coil L5, which is another feedback winding, is connected to the base and emitter of Q13 via a resistor R17. The collector of the NPN transistor Q14 is connected to the base of the transistor Q13.
Is connected to a control circuit CN which starts a signal generated at the same time as turning on as a synchronization signal, and the emitter of Q14 is connected to the negative terminal of the power supply E. When the transistor Q14 is turned on, the transistor Q13 is turned off.
Is a circuit that can control the dimming by controlling the conduction angle of the light by the control circuit CN. Further, for starting self-excited oscillation when the DC power supply E is connected, a starting circuit formed of a resistor or the like is also connected to the base of the transistor Q13. FIG.
These are idealized waveforms of the voltage (collector-emitter voltage) and current (collector current) of the transistors Q12 and Q13 when the conduction angle of the transistor Q13 is not controlled and when the conduction angle is controlled. The reason for making such a complicated circuit is that the oscillation frequency of the conventional self-excited inverter / series circuit is determined by the magnetic circuit and cannot be adjusted by varying the oscillation frequency. If the oscillation frequency can be varied, a lighting device capable of dimming using the variation in the impedance of the load current control element due to the frequency can be obtained.

The operation of FIG. 5 will be described. The current flowing through the capacitor C7 of this circuit is divided into the discharge tube LMP and the capacitor C8 after the discharge tube LMP is turned on, and before the LMP is turned on, there is a difference that only flows through the capacitor C8. Since there is no light, description will be made in a state before lighting. First, a case where the control circuit CN shown in FIG. 5 does not operate will be described. Since the base current flows through the transistor Q13 by the start circuit, the transistor Q13 is turned on.
The capacitor C7 is charged at the same time as the power supply E-capacitor C7-capacitor C8-inductor ID2-coil L3-transistor Q13-power supply E flows. Coil L3
Is a primary winding of a transformer TR2 using a saturable iron core. The voltage induced on the feedback winding of TR2 by the current flowing through L3 becomes negative on the black point side. Since a reverse voltage is applied between the base and the emitter of Q12, Q12 remains off. On the other hand, the current of the coil L5, which is another feedback winding of the transformer TR2, flows through the coil L5, the base-emitter of the transistor Q13, the resistor R17, and the coil L5.
Since Q13 is turned on deeply, the current of the coil L3, which is the collector current, increases more and more. The current flowing through the coil L3, which is the primary winding of the transformer TR2 using a saturable iron core, increases with time, and the magnetic flux of TR2 also increases with time. When the magnetic flux reaches the saturation magnetic flux, the increase in the magnetic flux stops, so that the voltage induced in the coil L5 becomes zero, and the base current of the transistor Q13 also becomes zero, so that the collector current of the transistor Q13 also becomes zero. At that time, the coils L4 and L4
5, a positive reverse voltage is generated on the black dot side, and the transistor Q1
2 is turned on by the base current flowing, and the transistor Q1 is turned on.
No. 3 is turned off by applying a reverse voltage between the base and the emitter. That is, the transistor Q12 is turned on and the transistor Q13 is turned off.
Transistor Q12-coil L3-inductor ID2-
The capacitor C8 is discharged with the capacitor C7, and a discharge current flows. The coil L3 is a primary winding of the feedback transformer TR2 using a saturable iron core, and the voltage induced in the feedback winding of TR2 by the current flowing through L3 becomes positive on the black point side. L4-resistor R16-
Transistor Q12 base-emitter-coil L4
To turn on Q12 deeply, so that the current of the coil L3, which is the collector current, further increases. On the other hand, the voltage induced in the coil L5, which is another feedback winding of the transformer TR2, applies a reverse voltage between the base and the emitter of the transistor Q13, so that Q13 remains off. The current flowing through the coil L3, which is the primary winding of the transformer TR2 using a saturable iron core, increases with time, and the magnetic flux of TR2 also increases with time. When the magnetic flux reaches the saturation magnetic flux, the increase in the magnetic flux stops, so that the voltage induced in the coil L4 becomes zero, and the base current of the transistor Q12 also becomes zero, so that the collector current of the transistor Q12 also becomes zero. Since then
The transistors Q12 and Q13 alternately turn on and off, and self-oscillate.

Next, the case where the discharge tube LMP shown in FIG. 5 is turned on and the control circuit CN operates will be described. For example,
A monostable multivibrator is used for the control circuit CN, and a synchronization signal is used as a signal when the transistor Q13 is turned on.
If the transistor Q14 is turned on after a certain time determined by the operation of the external variable resistor, the base current flows, and the transistor Q13 is turned off at that time. That is, the conduction angle (ON time) of Q13 can be varied by a change in the resistance of the variable resistor of the control circuit CN. Since the charging current and the discharging current of the capacitor C7 are the same, dimming is possible by controlling either the charging current or the discharging current. FIG. 6 shows Q1 when the conduction angle of the transistor Q13 is not controlled and when the conduction angle is controlled in the circuit of FIG.
2 shows ideal waveforms of the voltage (collector-emitter voltage) and current (collector current) of Q2 and Q13. FIG. 6A shows a case in which the conduction angle of the transistor Q13 is not controlled. The transistors Q12 and Q13 are alternately turned on and off, and the conduction angles are ず つ each. FIG. 6B shows the Q when the conduction angle of the transistor Q12 is not controlled and the conduction angle of the transistor Q13 is controlled to 1/2 and the ON is reduced to 1/4 and the OFF is reduced to 3/4.
12 and Q13, the current of Q13 becomes 50, so that the current of Q12 also becomes 50, and the discharge tube LM
Since the current of P also becomes 50, dimming is possible. This circuit utilizes the fact that the charging current and the discharging current of the capacitor C7 are equal to each other, and does not control the conduction angle of Q12, but controls only the conduction angle of Q13 to adjust the light. At this time, there is no change in the frequency (the reciprocal of the repetition period).

[0006]

A circuit for lighting a discharge tube using an inverter circuit usually has a function of dimming the discharge tube. In the dimming method, a circuit that uses a capacitor or an inductor as the load current control element, and uses the fluctuation of the operating frequency to change the impedance of the load current control element to change the impedance is often used as a simple circuit. In the self-excited inverter / series circuit described above, since the oscillation frequency is determined by the magnetic circuit, dimming cannot be performed by changing the oscillation frequency. As shown in FIG. A complicated circuit must be used to control the conduction angle of one of the transistors in the operation of the resistor. There is a problem that flickering occurs and, furthermore, the use of a transformer results in a large, expensive, and heavy device. By using a separately-excited inverter / series circuit,
It is easy to change the oscillation frequency and use the change in the impedance of the load current control element to perform dimming, but the oscillation circuit is a separate circuit and the use of a transformer makes it large, The same was expensive and heavy. Further, since this circuit is an oscillation circuit utilizing magnetic saturation, it is a circuit having a large area surrounded by a BH curve representing magnetic characteristics and a large loss. Further, in the conventional dimming method, all are manually controlled.For example, in an instrument panel or the like in a vehicle interior, the illuminance constantly fluctuates as the vehicle travels, and discharge occurs with time due to air conditioning, self-heating of an inverter circuit, and the like. Since the temperature of the tube wall also changes, it is necessary to constantly adjust the brightness. However, in reality, it was not possible to sufficiently control the light due to the inconvenience. Therefore, the emergence of self-excited inverters and series circuits whose oscillation frequency fluctuates with simple circuits that use less transformers and minimize the use of transformers, and the emergence of lighting devices that use self-excited inverters and series circuits whose frequency fluctuates, as well as dimming And self-excited inverters whose frequency varies with temperature and / or illuminance
There has been a demand for a lighting device that automatically adjusts light using a series circuit. The present invention solves such a problem, and operates in the same manner as a self-excited inverter / series circuit, and furthermore, the two transistors connected substantially in parallel to the power supply do not use a transformer. A self-running inverter / series circuit using a self-running multivibrator that is turned on / off by positive feedback of a resistor and a capacitor, and a lighting device using the self-running inverter / series circuit;
To provide a small-sized, light-weight, and inexpensive lighting device using a self-running inverter / series circuit, which performs dimming by changing at least one of the resistance of two resistors and the capacitance of two capacitors. And Note that elements that do not need to change resistance or capacitance even if they are described as variable resistors or variable capacitors in the drawings may be ordinary resistors or capacitors. The pulse waveform in this circuit is basically a rectangular pulse, and is a highly efficient waveform for lighting the discharge tube.

[0007]

In order to achieve the above-mentioned object, the first step of the present invention is to develop a self-running inverter / series circuit. In a circuit having two transistors of a free-running multivibrator alternately turned on and off by a positive feedback circuit combining two capacitors, at least one of the two transistors of the free-running multivibrator is connected in series to a DC power supply. Used as a transistor of a self-running inverter / series circuit that alternately turns on and off, and the remaining transistors of the self-running inverter / series circuit are driven by transistors of a self-running multivibrator and connected in series to a DC power supply If a circuit for turning on and off the two transistors alternately is used, a self-running inverter
It becomes a series circuit. Next, as a second stage of the present invention for achieving the above object, a self-propelled inverter / series circuit is used as a component of the lighting device. If a discharge tube is connected to the load, the lighting device uses a self-propelled inverter / series circuit. Further, as a third step of the present invention for achieving the above object, dimming of a lighting device using a self-running inverter / series circuit is performed, but two resistors used for positive feedback described in the first step are used. By changing at least one of the resistance of the device and the capacitance of the two capacitors, the variation of the impedance of the load current control element due to the fluctuating oscillation frequency is utilized, or the duty ratio of the fluctuating operation waveform and the duty ratio of the discharge tube are changed. Capacitors connected in an equivalent series (herein, elements that operate as if they are connected in series irrespective of the formation of a series circuit directly with the discharge tube are referred to as equivalent series) Utilization of interaction or fluctuation of load current control element impedance due to fluctuating oscillation frequency, and duty cycle of fluctuating operation waveform and equivalent series connection to discharge tube By using dimming interactions capacitor, the illumination apparatus using the self-propelled inverter series circuit. There is a method of manually and automatically changing the resistance of the resistor and the capacitance of the capacitor. To manually change the resistance of the resistor and the capacitance of the capacitor, a variable resistor or a variable capacitor may be used. External conditions that need to automatically change the resistance of the resistor and the capacitance of the capacitor are temperature and illuminance. The temperature sensor as a specific element is
Porcelain capacitors with temperature characteristics, thermistors, positive temperature coefficient thermistors, metal resistance temperature sensors, etc., the illuminance sensors are CdS, photodiodes, phototransistors,
PbS and the like. For example, instead of a variable resistor, CdS
If a ceramic capacitor having a temperature characteristic is used instead of the variable capacitor, a lighting device capable of dimming according to temperature and illuminance can be obtained. A self-running inverter / series circuit is a positive feedback circuit that uses a resistor and a capacitor, and is a pulse generation circuit that uses a self-running multivibrator that turns on and off two transistors alternately. Is an oscillation circuit. When converting the pulse width to frequency, the frequency is the reciprocal of the repetition period. All FETs used in this text are enhancement type MOSFETs. The semiconductor element to be used can replace the bipolar transistor and the FET with a slight change in the circuit other than that shown in the embodiment. It should be noted that the term “transistor” is used to represent a bipolar transistor and an FET. The FET has a parasitic diode between the drain and the source to absorb a surge voltage at the time of switching. However, the bipolar transistor has no parasitic diode. Therefore, a diode may be connected as needed. Of the complementary transistors, PNP transistors and P-channel FETs are often larger and more expensive than NPN transistors and N-channel FETs, but small signal PNs are used instead of power PNP transistors.
A circuit that is inexpensive by connecting the P transistor and the NPN transistor for power in a pseudo Darlington connection, an ordinary Darlington connection, or a two-stage amplifier circuit can be used. As the circuit, a circuit that speeds up or slows down the switching speed by using auxiliary driving transistors or capacitors, a circuit that prevents two transistors from turning on at the same time, or the like can be appropriately used.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION On behalf of Examples 1 to 3,
Example 1 will be described. A self-excited inverter / half-bridge circuit in which two transistors that are connected in series between the positive and negative terminals of a DC power supply and that alternately turn on and off are complementary bipolar transistors, and a case where the circuit is applied to a lighting device will be described. . The emitter of a PNP transistor as a first transistor is connected to the positive terminal of the DC power supply, the emitter of an NPN transistor as a second transistor is connected to the negative terminal of the DC power supply, and a connection point between collectors of the two transistors. , Between the connection points of two capacitors connected in series between the positive and negative terminals of the DC power supply,
A discharge tube and an inductor which is a load current control element are connected in series. The emitter of a third transistor, an NPN transistor, is connected to the negative terminal of the DC power supply, and a first Zener diode and a second resistor are connected in series between the collector of the third transistor and the base of the first transistor. . The cathode of the first Zener diode is the base side of the first transistor. A first resistor is connected between the positive terminal of the DC power supply and the collector of the third transistor. Connect the first and second variable resistors to the positive terminal of the DC power supply, connect the third and fourth resistors to the negative terminal of the DC power supply,
Connect the other terminals of the first and third resistors to the base of the second transistor, and connect the other terminals of the second and fourth resistors to the base of the third transistor. Connect to Connect a second variable capacitor between the collector of the second transistor and the base of the third transistor, and connect the first variable capacitor and the second Zener diode between the collector of the third transistor and the base of the second transistor Are connected in series. The anode of the second Zener diode is the base side of the second transistor. The Zener voltages of the first and second Zener diodes are lower than the DC power supply voltage, and the sum of the Zener voltages of the first and second Zener diodes is higher than the DC power supply voltage. This circuit becomes a self-running multivibrator circuit with the second and third transistors, and the first transistor is turned on and off by turning on and off the third transistor. The circuit is constituted by two transistors connected in series in a circuit to light a discharge tube comprising a self-running inverter / series half-bridge circuit. The on-off pulse width of the second and third transistors is determined by the time constant of the combination of the resistances of the two variable resistors and the variable capacitor connected to one end of the variable resistor. When at least one of the resistance of the resistor and the capacitance of the two variable capacitors changes, the impedance of the inductor, which is the load current control element, changes due to the change in the repetition period.
Fluctuations in the duty ratio of the operating waveform of the square-wave pulse voltage due to fluctuations in pulse width and interaction with capacitors connected in series to the DC power supply and equivalently connected to the discharge tube, or load currents due to fluctuations in the repetition period Fluctuations in the duty ratio of the operating waveform of the square-wave pulse voltage due to fluctuations in the impedance and pulse width of the control element inductor and the interaction with a capacitor connected in cascade to a DC power supply and equivalently connected in series to a discharge tube Thereby, a self-propelled inverter / series half-bridge circuit capable of dimming the discharge tube is obtained. When a lighting device that can automatically adjust dimming due to a change in temperature and / or a change in illuminance is used, at least one of the two variable resistors and the two variable capacitors is connected to a resistor according to temperature or illuminance. Or, in place of an element whose capacity changes, a lighting device using a self-propelled inverter / series half-bridge circuit that can automatically adjust the discharge tube according to a change in temperature and / or a change in illuminance. Also. Moreover, since this circuit does not use magnetic saturation, it is a circuit with little loss.

[0009]

Embodiment 1 FIG. 1 shows a first embodiment according to the first to third aspects of the present invention, in which the invention is applied to a self-running inverter / series half bridge circuit using bipolar transistors. This circuit uses a PNP
The emitter of the transistor Q1 is connected, the emitter of the NPN transistor Q2 is connected to the negative terminal of the DC power source E,
A discharge tube L is connected between a connection point W between the collectors of the two transistors and a connection point X where two capacitors C1 and C2 having the same characteristics are connected in series between the positive and negative terminals of the DC power supply E.
MP and an inductor ID1 which is a load current control element are connected in series. The emitter of the NPN transistor Q3 is connected to the negative terminal of the DC power supply, and the resistor R1 is connected between the positive terminal of the power supply and the collector of Q3. A Zener diode ZD is connected between the base of transistor Q1 and the collector of Q3.
1 and the resistor R2 are connected in series. The cathode of the Zener diode ZD1 is on the base side of Q1. Variable resistors VR1 and VR2 are connected to the positive terminal of the DC power supply, resistors R3 and R4 are connected to the negative terminal of the DC power supply E, and VR1 and R3 are connected.
Is connected to the base of transistor Q2, and VR2
And the base of the transistor Q3 is connected to the connection point of R4. A variable capacitor VC2 is connected between the collector of the transistor Q2 and the base of the transistor Q3, and a variable capacitor VC1 and a zener diode ZD2 are connected in series between the collector of Q3 and the base of Q2. The anode of the Zener diode ZD2 is on the base side of the transistor Q2. The sum of the Zener voltages of Zener diodes ZD1 and ZD2 is higher than the power supply voltage, and the Zener voltage of each of ZD1 and ZD2 is several volts lower than the power supply voltage. In this circuit, a self-running multivibrator circuit is formed by the transistors Q2 and Q3, and the transistor Q1 is turned on and off by turning on and off the transistor Q3. A circuit for illuminating the discharge tube by configuring two transistors. Variable resistor VR1, variable capacitor VC1, and variable resistor VR
2 and the variable capacitor VC2 determine the ON / OFF pulse width of the transistors Q1 and Q2. Therefore, if at least one of the resistance of VR1 and VR2 and the capacitance of VC1 and VC2 changes, the variation of the repetition period Or the interaction between the capacitors C1 and C2 connected in series equivalently to the fluctuation of the duty ratio of the rectangular pulse voltage due to the fluctuation of the pulse width, or The variation in the duty ratio of the rectangular wave pulse voltage due to the variation in the impedance of the inductor ID1, which is the load current control element, and the variation in the pulse width due to the variation in the repetition period, and the interaction between the capacitors C1 and C2 connected in series equivalently. , Self-propelled inverter / series heater capable of dimming the discharge tube LMP It can be the lighting device using a-bridge circuit. If at least one of the variable resistors VR1 and VR2 and the variable capacitors VC1 and VC2 is replaced with an element whose resistance or capacitance changes depending on temperature or illuminance, the temperature or / and the illuminance change automatically. It can also be used as a self-propelled inverter / series half-bridge circuit capable of dimming the discharge tube. As transistors to be used, Q1 and Q2 are power transistors, but Q3 may be a small signal transistor. This circuit includes a zener diode ZD2 connected to a variable capacitor VC1.
Are connected in series, the charging and discharging of VC1 cannot be exactly the same as when VC1 alone is connected. However, when there is no need to particularly mention in the description of this circuit, the small difference is I do not discuss.

The operation of FIG. 1 will be described. Power supply E
It will be described when is connected. When the DC power supply E is connected, a current flows between the base and the emitter of any one of the transistors Q2 and Q3. However, if a current flows between the base and the emitter of the transistor Q2 due to a slight difference in characteristics, the current flows from the power supply. Flows through the power supply E, the variable resistor VR1, the base-emitter of the transistor Q2, and the power supply E, and the power supply E turns on. Therefore, the collector voltage of the Q2 becomes a voltage close to the negative terminal of the DC power supply E. Since the voltage is applied to the base of transistor Q3 via variable capacitor VC2, Q3 remains off. In this circuit, the transistor Q
One of 2 and Q3 is on and the other is off. The following description will be made on the assumption that the transistors Q2 and Q3 in the self-running multivibrator are alternately turned on and off. Now, the transistor Q2 is turned off and the transistor Q3 is turned on. When the transistor Q3 is turned on, the collector voltage of the transistor Q3 becomes close to the negative terminal of the power supply E. Therefore, the base voltage of the transistor Q2 becomes close to the negative terminal of the DC power supply E via the variable capacitor VC1 and the Zener diode ZD2. Become. At this time, the current from the power supply via the transistor Q3 flows through the power supply E- (the base-emitter of the transistor Q1-the Zener diode ZD1-the resistor R2) and the parallel circuit of the (resistor R1) -the transistor Q3-the power supply E. . The transistor Q1 is turned on by this current, but the transistor Q2 is off. Therefore, a self-running inverter / series half bridge circuit is formed by Q1 and Q2 and capacitors C1 and C2. At this time, the current from the power supply via the transistor Q1 is represented by a power supply E-transistor Q1-discharge tube LMP-inductor ID
1-Capacitor C2-Power supply E flows to capacitor C2
Charge. This current is defined as i1. The charge of the capacitor C1 charged in the previous half cycle is
1-transistor Q1-discharge tube LMP-inductor ID
1- Discharge the capacitor C1. This current is defined as i2. The discharge tube LMP is turned on by the combined current of the charging current i1 of the capacitor C2 and the discharging current i2 of the capacitor C1. The connection point W between the transistors Q1 and Q2 is a voltage close to the positive terminal of the power supply E, and the base voltage of the transistor Q3 is about 0.7 V. Therefore, the variable capacitor VC2 includes the power supply E-transistor Q1-variable capacitor VC2-transistor Q3 And a current flows between the base-emitter and the power supply E to positively charge the connection point W side of VC2. On the other hand, the current flowing through the variable resistor VR1 is equal to the power supply E-variable resistor VR1.
-Zener diode ZD2-Variable capacitor VC1-
The current flows through the transistor Q3 to the power supply E to charge the VR1 side of VC1 positively. As the variable capacitor VC1 charges, the base voltage of the transistor Q2 gradually increases.
If that voltage rises to a voltage at which the base current of transistor Q2 flows, the current through variable resistor VR1 becomes
The power supply E-the variable resistor VR1-the base-emitter of the transistor Q2-the power supply E flows to turn on Q2. When the transistor Q2 is turned on, the collector voltage of the transistor Q2 decreases from a voltage close to the positive terminal of the DC power supply E to a voltage close to the negative terminal. Therefore, the base voltage of the transistor Q3 becomes negative due to the voltage charged in the variable capacitor VC2. As a result, Q3 is turned off, and the transistor Q1 is turned off by turning off Q3. Since the transistor Q1 is off and Q2 is on, the current flowing from the power supply through Q2 flows through the power supply E-capacitor C1-inductor ID1-discharge tube LMP-transistor Q2-power supply E, and at the same time, the capacitor C2
Charge 1. This current is defined as i3. The electric charge charged to the capacitor C2 in the previous half cycle is discharged to the capacitor C2, the inductor ID1, the discharge tube LMP, the transistor Q2, and the capacitor C2. This current is defined as i4. Due to the combined current of the charging current i3 of the capacitor C1 and the discharging current i4 of the capacitor C2, the discharge tube LMP flows in the opposite direction to light up. Since the current flowing through the variable capacitor VC1 is about 0.7 V at the base side of the transistor Q2, the current flows through the power source E, the resistor R1, the variable capacitor VC1, the zener diode ZD2, the base-emitter of the transistor Q2, the power source E, and the resistance of the VC1. The device R1 is positively charged. Note that Zener diodes ZD1 and ZD2
Since the sum of the Zener voltages is equal to or higher than the power supply voltage, no current flows through the variable capacitor VC1 via the ZD1.
This current does not turn on the transistor Q1. The current flowing through the variable capacitor VC2 is equal to the power supply E-variable resistor V
R2-Variable capacitor VC2-Transistor Q2-Power supply E flows, so that the VR2 side of VC2 is charged positively. With the charging of the variable capacitor VC2, the transistor Q3
Is gradually increased, but if the voltage rises to a voltage at which the base current of Q3 flows, the variable resistor VR
2 flows through the power supply E, the variable resistor VR2, the base-emitter of the transistor Q3, the power supply E,
3 is turned on, but the transistor Q1 is turned on by turning on Q3.
Is turned on, the base voltage of the transistor Q2 becomes negative due to the voltage charged in the variable capacitor VC1, so that Q2 is turned off. That is, the transistor Q1 is turned on and the transistor Q2 is turned off. Thereafter, the transistors Q2 and Q3, which are self-running multivibrators, are alternately turned on and off to connect the serially connected transistors Q1 and Q3.
And Q2 alternately turn on and off to form a lighting circuit for the discharge tube LMP composed of a self-running inverter / series half-bridge circuit.

The operation at the time of dimming will be described with reference to FIG.
FIG. 2 shows that the pulse width T2 of the variable resistor VR1 and the variable capacitor VC1 and the pulse width T3 of the variable resistor VR2 and the variable capacitor VC2 are the same and the duty ratio is 50.
At this time, the pulse width T2 of the variable resistor VR1 and the variable capacitor VC1 is kept as it is, and only the pulse width T3 of the variable resistor VR2 and the variable capacitor VC2 is reduced to が to set the duty ratio to 33 (１ ／). 6 is a time chart in which the relationship between the voltage (collector-emitter voltage) and the current (collector current) of the transistors Q1 and Q2 at that time is idealized. In FIG. 1, since the inductor ID1 and the capacitors C1 and C2 are connected, an actual waveform does not form such a clean rectangular pulse, but the concept is shown. FIG. 2A shows a pulse width T2 based on a time constant based on the resistance of the variable resistor VR1 and the capacitance of the variable capacitor VC1, and a pulse width T3 based on a time constant based on the resistance of the variable resistor VR2 and the capacitance of the variable capacitor VC2. Similarly, when the on / off duty ratio of the transistors Q1 and Q2 is 50, the on / off of Q1 and Q2 is 1
/ 2 each. The sum of the currents of the transistors Q1 and Q2 at this time is 1. FIG. 2B shows the pulse width T3 based on the time constant based on the resistance of the variable resistor VR2 and the capacitance of the variable capacitor VC2 while maintaining the pulse width T2 based on the time constant based on the resistance of the variable resistor VR1 and the capacitance of the variable capacitor VC1. The duty ratio is 33 when only the value of FIG. At this time, the on-time of the transistor Q2 is halved, so the current due to Q2 is halved. However, since the charging current and discharging current of the capacitors C1 and C2 connected in equivalent series are the same, the result is Then, the current of the transistor Q1 also becomes １ ／. At this time, the sum of the currents of the transistors Q1 and Q2 is 0.67 (2/3). That is, if the current when the pulse widths T2 and T3 are the same is 1, and the shorter pulse width of T2 and T3 when one pulse width is varied is T3, the repetition period T1 = T2
At + T3, the current at that time becomes 2T3 / T1. The above is the interaction between the change in the duty ratio due to the change in one pulse width and the equivalent series connection of the capacitors C1 and C2. This will be described using the currents i1 to i4. 1
Since the current values of the charging current and the discharging current of the two capacitors are the same, the current of the capacitor C1 is i2 = i3, and the current of the capacitor C2 is i1 = i4. Moreover, it is the total current of the discharge tube current. Therefore, if the on-time of the transistor Q2 is shortened, the i3 current and the i4 current are reduced.
As a result, the i1 current and the i2 current can also be reduced. Next, the influence of the operating frequency which is the reciprocal of the repetition period T1 = T2 + T3 is obtained. If an inductor or a capacitor is used as the load current control element, the impedance of the load current control element varies depending on the operation frequency. VR1 and VR2 resistors and variable capacitor VC1
By changing at least one of the capacitances VC1 and VC2, the repetition period T1 varies, so that dimming is possible.
In the above description, the dimming is performed when only one pulse width T3 is changed. However, the dimming can be performed by simultaneously changing the pulse width of T2. As mentioned above, this circuit
Since a rectangular wave pulse voltage is generated by the positive feedback, a pulse width T2 based on the time constant of the resistance of the variable resistor VR1 and the capacitance of the variable capacitor VC1 shown in FIG. 1, and the resistance of the variable resistor VR2 and the capacitance of the variable capacitor VC2 are shown. The transistors Q1 and Q
2 determines the on-off pulse width, so that the variable resistor V
R1 and VR2 resistors and variable capacitors VC1 and VC
Changing the impedance of the inductor ID1, which is the load current control element, due to the change of the repetition period T1 by changing at least one of the capacitances of the second and third capacitors.
Alternatively, an interaction between capacitors C1 and C2 connected in series equivalent to a change in the duty ratio of the rectangular pulse voltage due to a change in the pulse widths T2 and T3, or an inductor that is a load current control element due to a change in the repetition period T1. I
Variation in impedance of D1 and pulse widths T2 and T3
And the interaction of the capacitors C1 and C2 connected in series equivalently to the variation in the duty ratio of the rectangular wave pulse voltage due to the variation of the pulse voltage, results in a self-propelled inverter / series circuit capable of dimming the discharge tube. When the lighting device is capable of automatically adjusting light due to a change in temperature and / or a change in illuminance, at least one of the two variable resistors VR1 and VR2 and the two variable capacitors VC1 and VC2 is used. If a resistance or capacitance element is changed depending on temperature or illuminance, a self-propelled inverter / series circuit that can automatically dim the discharge tube due to a change in temperature or illuminance or a change in both. . This circuit works when the transistors Q2 and Q3 switch from on to off.
A reverse voltage is applied between the base and the emitter of the transistor. When the reverse voltage is high and adversely affects the transistor, it may be blocked with a diode. This circuit uses a PNP transistor in place of the resistor R1 and is connected in series to the transistor Q3.
If the transistor is driven by the transistor Q2, the zener diodes ZD1 and ZD2 become unnecessary.

The relationship between the circuit and the claims is as follows. This circuit has two transistors of a self-running multivibrator substantially connected in parallel to a DC power supply and turned on and off alternately by a positive feedback circuit combining a resistor and a capacitor. In the inverter / series circuit, at least one of the two transistors of the self-propelled multivibrator is connected in series to a DC power supply and used as a transistor of a series inverter circuit that is turned on and off alternately. It is a series circuit. This circuit is a lighting device using a self-running inverter / series circuit having two transistors which are connected in series to a DC power supply and alternately turned on and off according to claim 2, and are substantially connected in parallel to the DC power supply. Is turned on alternately by a positive feedback circuit that combines a resistor and a capacitor.
A lighting device using a self-running inverter / series circuit, wherein at least one of two transistors of the self-running multivibrator to be turned off is used as a transistor of the self-running inverter / series circuit. This circuit comprises at least one of two transistors of a free-running multivibrator substantially connected in parallel to a DC power supply and alternately turned on and off by a positive feedback circuit combining a resistor and a capacitor. In a lighting device which is used as a transistor of a self-running inverter / series circuit which is connected in series to a DC power supply and alternately turns on and off, at least one of the resistance of the resistor and the capacitance of the capacitor is changed. Thus, a lighting device using a self-propelled inverter / series circuit, which performs dimming by one of the following groups. a. Utilization of fluctuation of load current control element impedance due to fluctuating oscillation frequency b. Utilization of the interaction between the duty ratio of the fluctuating operation waveform and the capacitor connected in series to the discharge tube c. Use of the fluctuation of the load current control element impedance due to the fluctuating oscillation frequency, and use of the interaction between the duty ratio of the fluctuating operation waveform and the capacitor connected in series to the discharge tube

[0013]

Embodiment 2 FIG. 3 shows a second embodiment according to the first to third aspects of the present invention, in which the invention is applied to a self-running inverter / series modified half-bridge circuit using bipolar transistors. . In this circuit, the positive terminal of the DC power
The collector of the PN transistor Q4 is connected, the emitter of the NPN transistor Q5 is connected to the negative terminal of the DC power supply, and the capacitor C4 and the output transformer TR1 are connected between the connection point of the emitter of Q4 and the collector of Q5 and the negative terminal of the DC power supply.
Are connected in series. A discharge tube LMP and a capacitor C5 as a load current control element are connected in series to a coil L2 as a secondary winding of the transformer TR1. The emitters of NPN transistors Q6 and Q7 are connected to the negative terminal of the DC power supply.
4 and the base of Q7 is connected to the collector of Q6. The positive terminal of the DC power supply E and the transistor Q6
A resistor R5 is connected between the collectors. The variable resistors VR3 and VR4 are connected to the positive terminal of the DC power source E, and the resistors R7 and R8 are connected to the negative terminal of the DC power source E.
And the other terminal of R7 are connected to the base of transistor Q5, and the other terminals of VR4 and R8 are connected to the base of transistor Q6. A variable capacitor VC3 is connected between the collector of the transistor Q6 and the base of the transistor Q5, and a variable capacitor VC4 is connected between the collector of Q5 and the base of Q6. The anode of the diode D is connected to the positive terminal of the DC power supply E, the cathode of D is connected to the capacitor C3 and the resistor R6, another terminal of C3 is connected to the connection point of the transistors Q4 and Q5, and another terminal of R6 is connected. The terminal is connected to the base of the transistor Q4. Note that a resistor R9 is connected between the base of the transistor Q7 and the negative terminal of the power supply E to prevent malfunction due to leakage current. In this circuit, the transistors Q5 and Q6 form a self-running multivibrator circuit. The transistor Q7 is turned on and off when Q6 is turned on and off, and the transistor Q4 is turned on and off when Q7 is turned on and off. It becomes a series-connected transistor of a self-propelled inverter / series modified half-bridge circuit.

The operation of FIG. 3 will be described. The transistors Q5 and Q6 in FIG. 3 correspond to the transistors Q2 and Q3 in FIG. 1 and have almost the same operation. Therefore, the detailed description of the self-running multivibrator using Q5 and Q6 is omitted, and the transistors operate stably. Explanation will be given in the state. Although the zener diode ZD2 is connected in series to the variable capacitor VC1 in FIG. 1, the circuit of FIG. 3 performs the same operation when ZD2 is short-circuited. It is assumed that a self-running multivibrator composed of transistors Q5 and Q6 has Q5 turned off and Q6 turned on. When the transistor Q6 turns on, the transistor Q
7 is turned off, so that capacitor C3 in the previous half cycle
The base current flows to the transistor Q4 via the resistor R6 due to the electric charge (the charging operation will be described later), and the transistor Q4 is turned on. Since the transistor Q4 is on and Q5 is off, the current from the power supply is equal to the power supply E-
The current flows through the transistor Q4, the capacitor C4, the coil L1, and the power supply E to charge C4. By this current, the discharge tube LMP is lit by the current flowing through the coil L2 and the capacitor C5. If the self-running multivibrator by the transistors Q5 and Q6 is inverted, Q5 turns on and Q6 turns off. By turning off the transistor Q6, the transistor Q
Since 7 is turned on, the base voltage of the transistor Q4, which is the collector voltage of the transistor Q7, becomes a voltage close to the negative terminal of the power supply E, and Q4 is turned off. Since the transistor Q4 is off and the transistor Q5 is on, the load charged in the capacitor C4 in the previous half cycle is discharged to the capacitor C4 to the transistor Q5 to the coil L1 to the capacitor C4.
With this current, the discharge tube LMP is lit by the current flowing in the opposite direction via the coil L2 and the capacitor C5. In addition,
At this time, the current from the power supply E via the diode D is
The power flows through the power supply E, the diode D, the capacitor C3, the transistor Q5, and the power supply E, and charges C3 to a voltage close to the power supply voltage. By the electric charge charged in the capacitor C3,
In the next half cycle, transistor Q4 turns on. Thereafter, the transistors Q4 and Q5, which are self-propelled multivibrators, are alternately turned on and off, and the transistors Q4 and Q5 connected in series are alternately turned on and off. L
MP lights up. This circuit also uses the variable resistor V shown in FIG.
The pulse width based on the time constant based on the resistance of the resistor R3 and the capacitance of the variable capacitor VC3, and the pulse width based on the time constant based on the resistance of the variable resistor VR4 and the capacitance of the variable capacitor VC4, the ON-OFF pulse width of the transistors Q4 and Q5. By changing at least one of the resistance of the variable resistors VR3 and VR4 and the capacitance of the variable capacitors VC3 and VC4, the impedance of the load current control element fluctuates due to the fluctuation of the repetition cycle T1, or Fluctuation of the duty ratio of the rectangular wave pulse voltage due to fluctuation of pulse widths T2 and T3 and interaction with a capacitor connected in series equivalently, or repetition period T1
The dimming of the discharge tube is caused by the variation of the impedance of the load current control element due to the variation of the pulse width and the variation of the duty ratio of the rectangular pulse voltage due to the variation of the pulse widths T2 and T3 and the interaction with the capacitor connected in series equivalently. It becomes a possible self-running inverter / series modified half-bridge circuit. When the lighting device is capable of automatically adjusting light due to a change in temperature and / or a change in illuminance, at least one of the two variable resistors VR3 and VR4 and the two variable capacitors VC3 and VC4 is used. A self-propelled inverter that can automatically adjust the discharge tube by changing the temperature or the illuminance, or both, by replacing the element whose resistance or capacitance changes with temperature or illuminance.
It becomes a series modified half bridge circuit. If the reverse voltage between the base and the emitter of the transistor Q4 is too high when the transistor Q7 is on, it may be blocked by a diode.

The relationship between the circuit and the claims is as follows. This circuit has two transistors of a self-running multivibrator substantially connected in parallel to a DC power supply and turned on and off alternately by a positive feedback circuit combining a resistor and a capacitor. In the inverter / series circuit, at least one of the two transistors of the self-propelled multivibrator is connected in series to a DC power supply and used as a transistor of a series inverter circuit that is turned on and off alternately. It is a series circuit. This circuit is a lighting device using a self-running inverter / series circuit having two transistors which are connected in series to a DC power supply and alternately turned on and off according to claim 2, and are substantially connected in parallel to the DC power supply. Is turned on alternately by a positive feedback circuit that combines a resistor and a capacitor.
A lighting device using a self-running inverter / series circuit, wherein at least one of two transistors of the self-running multivibrator to be turned off is used as a transistor of the self-running inverter / series circuit. This circuit comprises at least one of two transistors of a free-running multivibrator substantially connected in parallel to a DC power supply and alternately turned on and off by a positive feedback circuit combining a resistor and a capacitor. In a lighting device which is used as a transistor of a self-running inverter / series circuit which is connected in series to a DC power supply and alternately turns on and off, at least one of the resistance of the resistor and the capacitance of the capacitor is changed. Thus, a lighting device using a self-propelled inverter / series circuit, which performs dimming by one of the following groups. a. Utilization of fluctuation of load current control element impedance due to fluctuating oscillation frequency b. Utilization of the interaction between the duty ratio of the fluctuating operation waveform and the capacitor connected in series to the discharge tube c. Use of the fluctuation of the load current control element impedance due to the fluctuating oscillation frequency, and use of the interaction between the duty ratio of the fluctuating operation waveform and the capacitor connected in series to the discharge tube

[0016]

Third Embodiment FIG. 4 shows a third embodiment according to the first to third aspects of the present invention, in which the present invention is applied to a self-running inverter / series full bridge circuit using FETs. In this circuit, the P-channel FETs Q8 and Q8
10 are connected, the N-channel FETs Q9 and Q11 are connected to the negative terminal of the DC power supply, and a discharge is caused between the connection point Y between the drains of Q8 and Q9 and the connection point Z between the drains of Q10 and Q11. A tube LMP and a capacitor C6 as a load current control element are connected in series. The variable resistors VR5 and VR6 are connected to the positive terminal of the DC power source E, and the resistors R11 and R13 are connected to the negative terminal of the DC power source E.
The other terminals of 5 and R13 are connected to the gate of FET Q11, and the other terminals of VR6 and R11 are connected to the gate of FET Q9. A variable capacitor VC5 is connected between the drain of the FET Q9 and the gate of the FET Q11, and a variable capacitor VC6 is connected between the drain of Q11 and the gate of Q9. A resistor R14 is connected between the drain of the FET Q9 and the gate of the FET Q10, and a resistor R15 is connected between the drain of the FET Q11 and the gate of the FET Q8. Resistors R10 and R12 are connected between the gate of the FET Q8 and the gate of the FET Q10 and the positive terminal of the DC power supply E for gate protection, respectively. This circuit is
ETQ9 and Q11 form a self-running multivibrator circuit. The FET Q9 is turned on and off by turning on and off the FET Q9, and the FET Q8 is turned on and off by turning on and off the FET Q11.
Are turned on and off, the FETs Q8 to Q11 form a self-running inverter / series full bridge circuit.

The operation of FIG. 4 will be described. FET Q1 of FIG.
1 and Q9 correspond to the transistors Q2 and Q3 in FIG. 1 and have almost the same operation. Therefore, a detailed description of the self-running multivibrator by Q11 and Q9 will be omitted, and the explanation will be made in a state where the operation is stable. Although the zener diode ZD2 is connected in series with the variable capacitor VC1 in FIG. 1, the same operation is performed in the circuit of FIG. 4 if ZD2 is short-circuited. It is assumed that a self-running multivibrator constituted by FETs Q9 and Q11 has Q9 turned off and Q11 turned on. Since a negative voltage is applied to the gate of the FET Q8 when the FET Q11 is turned on, Q8 is turned on.
Since no voltage is applied to the gate of the FET Q10 due to the turning off of Q9, Q10 turns off. Since the FETs Q8 and Q11 are on and the FETs Q9 and Q10 are off, the current from the power supply is equal to the power supply E-FET Q8-capacitor C6-discharge tube LM
It flows with P-FETQ11-power supply E. The discharge tube LMP is turned on by this current. Next, if the self-running multivibrator by the FETs Q9 and Q11 is inverted, Q9 is turned on and Q11 is turned off. When the FET Q9 is turned on, the FET Q
Q10 is turned on because a negative voltage is applied to the gate of 10, but Q8 is turned off because no voltage is applied to the gate of FET Q8 due to turning off of FET Q11. FET
Since Q8 and Q11 are off and FETs Q9 and Q10 are on, the current from the power supply flows through power supply E-FETQ10-discharge tube LMP-capacitor C6-FETQ9-power supply E. The discharge tube LMP is turned on by this reverse current.
Thereafter, the self-propelled multivibrators FET Q9 and Q1
By the alternate on-off operation of 1, the FETs Q8 and Q10 are alternately turned on and off, and the discharge tube LMP is turned on by the self-running inverter / series full bridge circuit. This circuit also has a pulse width based on a time constant based on the resistance of the variable resistor VR5 and the capacitance of the variable capacitor VC5 and a pulse width based on a time constant based on the resistance of the variable resistor VR6 and the capacitance of the variable capacitor VC6 shown in FIG. FET Q9 and Q11
Of the variable resistor VR
5 and VR6 and variable capacitors VC5 and VC6
By changing at least one of the capacities of
A change in the impedance of the capacitor C6, which is a load current control element, due to the change in the repetition period T1, or a change in the duty ratio of the rectangular wave pulse voltage due to the change in the pulse widths T2 and T3. Or the variation of the duty ratio of the rectangular wave pulse voltage due to the variation in the impedance of the load current control element due to the variation in the repetition period T1 and the variation in the pulse widths T2 and T3. By the action, it becomes a self-propelled inverter / series full bridge circuit capable of dimming the discharge tube. When a lighting device that can automatically adjust dimming due to a change in temperature and / or a change in illuminance is used, two variable resistors VR are used.
5 and VR6 and two variable capacitors VC5 and VC6
If at least one of the elements is replaced with an element whose resistance or capacitance changes depending on temperature or illuminance, a self-propelled inverter capable of automatically dimming the discharge tube by a change in temperature or illuminance or a change in both.・ It becomes a series full bridge circuit.

The relationship between the circuit and the claims is as follows. This circuit has two transistors of a self-running multivibrator substantially connected in parallel to a DC power supply and turned on and off alternately by a positive feedback circuit combining a resistor and a capacitor. In the inverter / series circuit, at least one of the two transistors of the self-propelled multivibrator is connected in series to a DC power supply and used as a transistor of a series inverter circuit that is turned on and off alternately. It is a series circuit. This circuit is a lighting device using a self-running inverter / series circuit having two transistors which are connected in series to a DC power supply and alternately turned on and off according to claim 2, and are substantially connected in parallel to the DC power supply. Is turned on alternately by a positive feedback circuit that combines a resistor and a capacitor.
A lighting device using a self-running inverter / series circuit, wherein at least one of two transistors of the self-running multivibrator to be turned off is used as a transistor of the self-running inverter / series circuit. This circuit comprises at least one of two transistors of a free-running multivibrator substantially connected in parallel to a DC power supply and alternately turned on and off by a positive feedback circuit combining a resistor and a capacitor. In a lighting device which is used as a transistor of a self-running inverter / series circuit which is connected in series to a DC power supply and alternately turns on and off, at least one of the resistance of the resistor and the capacitance of the capacitor is changed. Thus, a lighting device using a self-propelled inverter / series circuit, which performs dimming by one of the following groups. a. Utilization of fluctuation of load current control element impedance due to fluctuating oscillation frequency b. Utilization of the interaction between the duty ratio of the fluctuating operation waveform and the capacitor connected in series to the discharge tube c. Use of the fluctuation of the load current control element impedance due to the fluctuating oscillation frequency, and use of the interaction between the duty ratio of the fluctuating operation waveform and the capacitor connected in series to the discharge tube

[0019]

As described above, according to the present invention, there is provided a self-running multivibrator which is substantially connected in parallel to a DC power supply and which is turned on and off alternately by a positive feedback circuit combining a resistor and a capacitor. In a self-running inverter / series circuit having two transistors, at least one of two transistors of the self-running multivibrator is used as a transistor of a series inverter circuit that is connected in series to a DC power supply and alternately turns on and off. A self-propelled inverter / series circuit. Also, in a lighting device using a self-running inverter / serial circuit having two transistors that are connected in series to a DC power supply and that alternately turn on and off, a resistor and a capacitor are substantially connected in parallel to the DC power supply to form a resistor and a capacitor. A self-running inverter / series circuit using at least one of two transistors of a self-running multivibrator alternately turned on / off by a combined positive feedback circuit as a transistor of the self-running inverter / series circuit. The used lighting device can be used. Further, at least one of the two transistors of the free-running multivibrator that is connected in parallel to the DC power supply and alternately turned on and off by a positive feedback circuit combining a resistor and a capacitor is connected in series to the DC power supply. In a lighting device used as a transistor of a self-running inverter / series circuit that is connected and turned on and off alternately, by changing at least one of the resistance of the resistor and the capacitance of the capacitor, the variation of the repetition period is changed. The impedance of the load current control element fluctuates, or the duty ratio of the rectangular pulse voltage fluctuates due to the fluctuation of the pulse width, and the interaction with the capacitor connected in series equivalent to the load, or the repetition period fluctuates. Square-wave pulse voltage due to fluctuations in the impedance and pulse width of the current control element It can be of the interaction between a capacitor connected variations and equivalent series of duty ratio and the lighting device using a self-propelled inverter series circuit capable dimming of the discharge tube. The self-running inverter / series circuit does not require a separate oscillation circuit unlike the separately-excited inverter circuit, and does not require a feedback transformer like the self-excited inverter circuit. A lightweight, inexpensive inverter circuit can be provided. In addition, if a discharge tube is connected to the load of the self-propelled inverter / series circuit, a lighting device using a small, lightweight, and inexpensive inverter circuit with a small loss can be provided. In addition, the lighting device using the self-propelled inverter / series circuit has an effect that a circuit capable of manually or automatically adjusting the light by a simple method can be provided.

[Brief description of the drawings]

FIG. 1 is a circuit diagram to which a first embodiment of the present invention is applied;
Self-running inverter with variable pulse width using bipolar transistors and NPN bipolar transistors
This is a lighting device that adjusts light using a series half-bridge circuit.

FIG. 2 is a time chart of a voltage waveform and a current waveform of two transistors when dimming is performed by changing a duty ratio due to a change in one pulse width in the circuit of FIG.

FIG. 3 is a circuit diagram to which the second embodiment of the present invention is applied;
This is a lighting device that uses only a bipolar transistor and has a variable pulse width, and that uses a self-running inverter / series modified half-bridge circuit to perform dimming.

FIG. 4 is a circuit diagram to which the third embodiment of the present invention is applied, in which dimming is performed using a self-running inverter / series full-bridge circuit with a variable pulse width using a P-channel FET and an N-channel FET. It is a lighting device.

FIG. 5 is a circuit diagram according to the prior art, which is a lighting device that uses a self-excited inverter / modified half-bridge circuit with a fixed oscillation frequency, using an NPN bipolar transistor and a feedback transformer, and dimming. .

6 is a time chart of a voltage waveform and a current waveform of two transistors when dimming is performed by changing a duty ratio due to a change in one pulse width in the circuit of FIG. 5;

[Explanation of symbols]

E DC power supply R1 to R17 Resistor C1 to C8 Capacitor VR1 to VR6 Variable resistor VC1 to VC6 Variable capacitor Q1 to Q14 Bipolar transistor or FE
TD diode TR1 to TR2 Transformer L1 to L5 Transformer coil T1 Pulse repetition period T2 Pulse width T3 Shorter pulse width LMP Discharge tube

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Harumi Suzuki 7-29-3 Kita-Terao, Tsurumi-ku, Yokohama, Kanagawa

Claims (3)

[Claims] 1. A self-running inverter / series circuit having two transistors of a self-running multivibrator substantially connected in parallel to a DC power supply and alternately turned on and off by a positive feedback circuit combining a resistor and a capacitor. 3. The self-running inverter / series circuit according to claim 1, wherein at least one of the two transistors of the self-running multivibrator is used as a transistor of a series inverter circuit that is connected in series to a DC power supply and alternately turns on and off. 2. It is connected in series to a DC power supply and turned on alternately.
In a lighting device using a self-running inverter / series circuit having two transistors that are turned off, a self-running inverter that is connected in parallel to a DC power supply and that is turned on and off alternately by a positive feedback circuit combining a resistor and a capacitor is provided. A lighting device using a self-running inverter / series circuit, wherein at least one of two transistors of the running multivibrator is used as a transistor of the self-running inverter / series circuit. 3. A self-propelled multivibrator, which is connected to a DC power supply in parallel and turned on and off alternately by a positive feedback circuit combining a resistor and a capacitor. In a lighting device connected as a series connection to a power supply and used as a transistor of a self-running inverter / series circuit that is alternately turned on and off, by changing at least one of the resistance of the resistor and the capacitance of the capacitor, A lighting device using a self-propelled inverter / series circuit, which controls light using one of the groups. a. Utilization of fluctuation of load current control element impedance due to fluctuating oscillation frequency b. Utilization of the interaction between the duty ratio of the fluctuating operating waveform and a capacitor connected in series with the discharge tube c. Use of the fluctuation of the impedance of the load current control element due to the fluctuating oscillation frequency, and use of the interaction between the duty ratio of the fluctuating operation waveform and the capacitor connected in series equivalent to the discharge tube