JP2001284082A - Fluorescent lighting device - Google Patents

Abstract

(57) [Summary] A fluorescent lamp capable of detecting any of a single Emiless state, a double Emiless state, a contact failure, and an abnormally high voltage, and reliably preventing abnormal heat generation near a filament or a contact failure portion. A lighting device is provided. SOLUTION: A capacitor CS1 for cutting a direct current is provided in series between a current limiting choke coil and a fluorescent lamp FLR1 at an output of a high frequency inverter circuit. Abnormality detection for monitoring the DC superimposed high-frequency voltage generated between both electrodes of the fluorescent lamp FLR1
A protection circuit 16 is provided. When the DC superimposed high-frequency voltage exceeds at least one of the predetermined thresholds set for the positive and negative polarities,
The two electrodes of the fluorescent lamp FLR1 are short-circuited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescent lamp lighting device comprising a fluorescent lamp as a load connected to the output of a high frequency inverter circuit.

[0002]

2. Description of the Related Art Fluorescent lamps are generally used for lighting provided in showcases and the like, and fluorescent lamp lighting devices such as showcases have also been converted to inverters along with the conversion of electrical products into inverters. A fluorescent lamp lighting device of an inverter for a fluorescent lamp such as a showcase, that is, a fluorescent lamp lighting device of a series resonance lighting system using a high-frequency inverter circuit,
Usually, about 6 to 10 fluorescent lamps are connected to one lighting device as a load and are turned on. In general, many showcases do not have a manager, and it is determined whether the fluorescent lamp has reached the end of its life. Tubes were replaced as appropriate.

On the other hand, at the end of the life of the fluorescent tube, the emitter (electron emitting material) of one end or both ends of the filament is mainly scattered and consumed and disappears, so that one end or both ends of the fluorescent lamp are not lit. This is generally called Emiless (also called emitterless) of a fluorescent tube. That is, Emiless is an abnormality that appears in a fluorescent lamp at the end of its life and means the loss of the electron-emitting substance applied to the filament. There are two types of Emiless, one with only one filament in the Emiless state, and the other with both filaments in the Emiless state. Becomes

Since the one-sided Emiless state is a half-wave discharge state, almost no current flows in one direction, and more current flows in the opposite direction. In this case, due to the Joule heat due to the filament current and the collision energy of the electrons due to the half-wave discharge, the temperature on the Emiless side end increases intensively. That is, when the half-wave discharge is performed, although the output voltage and the current hardly increase, the tube wall generates abnormal heat as compared with the normal lighting.

[0005] That is, in a normal lighting state in which electrons are satisfactorily emitted from the filaments at both ends of the fluorescent lamp, the reciprocating electrons at both ends of the fluorescent tube are balanced, but the emission of electrons from one filament becomes worse ( One-sided Emiless state)
Then, the rectification phenomenon appears due to the imbalance of the reciprocating electrons at both ends of the fluorescent tube. In other words, the fluorescent tube at the end of its life gradually approaches the one-electrode vacuum tube and a rectifying action occurs.
In addition, if the fluorescent lamp continues to be lit as it is in the one-sided Emiless state, both sides will be in the Emiless state. In the both Emires state, it means no discharge of the fluorescent tube, and the load becomes light load (high impedance). Therefore, the tube voltage naturally rises sufficiently.

In a single-emissive state of the fluorescent tube, the tube voltage usually rises and the output current of the inverter increases. However, in the case of half-wave discharge, both the output voltage and the current do not increase so much. Abnormal heat generation of the tube wall occurs.
Compared with a general tube having a diameter of about 32 mm of such a fluorescent tube,
In a slim tube having a diameter of about 16 mm, which has been widely used in recent years, since the filament and the tube wall are close to each other, and the temperature of the tube wall rises greatly due to abnormal heat generation, an abnormal temperature rise countermeasure circuit is added to the general tube.

An abnormal heat generation phenomenon due to a contact failure of a connection portion on a high-frequency circuit (inverter circuit) is an abnormal phenomenon caused by a high-frequency arc discharge near DC which is a discharge phenomenon at a contact failure section. As compared with the low frequency (50/60 Hz), in the high frequency circuit, due to poor contact, an arc discharge phenomenon is more likely to occur in that portion. When an arc discharge occurs, the portion generates abnormal heat, and there is a risk of causing a fire if the state continues for a long time.

[0008]

However, when the tube wall temperature rises with a thick tube having a diameter of about 32 mm, the filament and the tube wall are separated from each other. However, the diameter of the fluorescent tube, which is ideal in terms of luminous efficiency, is a slim tube with a diameter of 16 mm. Therefore, in a conventional fluorescent lamp lighting device of a series resonance lighting system using a high frequency inverter circuit, an end-of-life tube detection circuit utilizing an increase in end-of-life tube voltage detects an end-of-life tube and an increase in tube voltage. I was This end-of-life tube detection circuit was able to detect the one-sided emiless state of a general (32 mm) fluorescent tube relatively reliably, but it reliably detected all abnormal states such as the one-sided emiless discharge state, the two-sided emiless state, and the poor contact. There was a problem that could not be done. Further, considering the measures to increase the wall temperature of the 16 mm tube, it becomes more difficult.

If a circuit for detecting a single Emiless state, a double Emiless state, a contact failure, an abnormally high voltage or the like is provided in a conventional circuit, the circuit becomes complicated and occupies a large space. There was a problem that cost increased. Therefore, development of a fluorescent lamp lighting device capable of detecting such abnormal high voltage or the like with a simple circuit has been desired.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art, and can detect any one-sided Emiless discharge state, both-sided Emiless state, poor contact, and abnormally high voltage. An object of the present invention is to provide a fluorescent lamp lighting device capable of reliably preventing abnormal heat generation such as a defective portion.

[0011]

According to a first aspect of the present invention, there is provided a fluorescent lamp lighting apparatus in which a current limiting choke coil (L) and a fluorescent tube as a load are connected in series to an output terminal of a high-frequency inverter circuit. This is a multi-light fluorescent lamp lighting device in which a plurality of circuits of an LC resonance lighting method using a capacitor (C) connected in parallel with a tube are connected in parallel, and a DC current cutting capacitor is inserted in series with a choke coil in the resonance circuit. Each circuit is provided with an abnormality detection / protection circuit for monitoring the voltage generated on the fluorescent tube side. The abnormality detection / protection circuit has a predetermined threshold in which the DC superimposed high-frequency voltage is set to both positive and negative polarities. When at least one of the values exceeds a predetermined time, only the circuit exceeding the threshold short-circuits between the two poles of the fluorescent tube.

Further, in the fluorescent lamp lighting device according to the second aspect of the present invention, the abnormality detection / protection circuit includes a voltage dividing resistor for dividing the DC superimposed high frequency voltage, and a polarity connected between the voltage dividing resistors. A series circuit of a pair of different Zener diodes and a bidirectional photocoupler, a relay that is energized and controlled when the photocoupler output continues for a predetermined time, and a contact of a relay connected in parallel between both poles of the fluorescent tube. It is configured.

[0013]

Next, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is an electric circuit diagram of a fluorescent lamp control device 10 of the present invention, and FIG.
FIG. 3 is a diagram showing a state of connection to LR1, FIG. 3 shows a voltage waveform F1 during normal lighting, a voltage waveform F2 during one-sided Emiless discharge, and a voltage waveform F3 during both-sided Emiless detected by the abnormality detection / protection circuit 16. The figure which shows the relationship with the voltage waveform F4 at the time of a contact failure is each shown.

The fluorescent lamp lighting device 10 is connected to a full-wave rectifier D1 via a noise filter 11 with a commercial AC power supply (AC 200 V, 50/60 Hz in this case) as an input, and outputs the output of the full-wave rectifier D1 (plus side). Is a switching element F composed of a field effect transistor (FET)
ET2 (drain terminal) connected to full-wave rectifier D1
The output on the (minus side) is connected to a switching element FET1 (source terminal), which is also a field effect transistor.

A switching element FET2 (source terminal) and a switching element FET1 (drain terminal)
And the switching elements FET2 (gate terminal) and FET1 (gate terminal)
It is connected to the. Further, between the plus side output and the minus side output of the full-wave rectifier D1, resistors R1 and R2 are connected in series, a capacitor C1 is connected in parallel with the resistor R1, and a capacitor C2 is connected in parallel with the resistor R2. Have been. That is, the switching element FET2, the switching element FET1, the drive circuit 15, and the like constitute a high-frequency inverter circuit.

A rectifying element D2 (positive side) is connected to the full-wave rectifying element D1 (positive side).
Electrolytic capacitor C3 (positive side) for 2 (minus side)
Is connected. That is, with the rectifier D2 and the electrolytic capacitor C3 connected in series, the rectifier D2 and the electrolytic capacitor C3 are connected in parallel with the resistor R1.

A rectifying element D3 (minus side) is connected to the full-wave rectifying element D1 (minus side), and an electrolytic capacitor C4 (minus side) is connected to the rectifying element D3 (plus side). That is, with the rectifier D3 and the electrolytic capacitor C4 connected in series, the rectifier D3
And the electrolytic capacitor C4 are connected in parallel with the resistor R2.

A rectifying element D4 (positive side) is connected between the capacitor C3 (positive side) and the rectifying element D2,
A rectifying element D5 (plus side) is connected in series to the rectifying element D4 (minus side), and the rectifying element D5 (minus side) is connected between the rectifying element D3 and the electrolytic capacitor C4.
The rectifiers D4 and D5 are connected in parallel with the capacitors C3 and C4.

From the switching element FET2 (source terminal) and the switching element FET1 (drain terminal), a coil L1 is interposed and branched there, and one of them branches between the rectifying element D4 (minus side) and the rectifying element D5 (plus side). Connected, the other is a choke coil (470 μH) CH1,
DC current cutting capacitor (0.33μF / 250
V) Connected to one side of a filament F11 provided at one end of the fluorescent lamp (FLR732T5H = slim tube with a diameter of 16 mm) FLR1 via CS1.

One side of the filament F12 provided at the other end of the fluorescent lamp FLR1 is connected between the capacitors C1 and C2 connected in parallel to the rectifying element D1, and is provided at one end of the fluorescent lamp FLR1. Between the other side of the filament F11 and the other side of the filament F12 provided at the other end of the fluorescent lamp FLR1, a capacitor (0.012 μF / 1.6K) for setting a resonance frequency when the fluorescent lamp FLR1 is turned on.
V) Cf1 is connected. R11 is a resistor (68
KΩ · 1W), R12 is a resistance (3.3KΩ) and the fluorescent lamp F
One side of a filament F11 provided at one end of the LR1 and a filament F provided at the other end of the fluorescent lamp FLR1.
12 are connected in series between one side.

A power supply circuit 12 for a control circuit is connected to the output side of the noise filter 11 in parallel with the full-wave rectifier D1. The output side of the power supply circuit 12 for the control circuit It is connected to the circuit 14. That is, the start control circuit 13 and the oscillation circuit 14 are configured to operate with a predetermined output power from the control circuit power supply circuit 12. The ground 17 of the control circuit power supply circuit 12 is connected to the start control circuit 13 and the oscillation circuit 14.

A transistor TR (emitter) is connected to the control circuit power supply circuit 12. A resistor R3 is connected between the base and the emitter of the transistor TR, and the transistor TR (base) is connected to a resistor R4. It is connected to the start control circuit 13 via the power supply. The output side of the start control circuit 13 is connected to the oscillation circuit 14, and the output side of the oscillation circuit 14 is connected to the drive circuit 15.

The transistor TR (collector) is connected to one side of a relay RY1 provided in the abnormality detection / protection circuit 16, and the other side of the relay RY1 is connected to a ground 17 via a thyristor SCR1 and a resistor R15. Pertaining,
The abnormality detection / protection circuit 16 is configured to detect the voltage between both ends of the fluorescent lamp FLR1 (FIG. 2). in this case,
The abnormality detection / protection circuit 16 detects the one-sided Emiless state of one of the filaments F11 or F12 of the fluorescent lamp FLR1, the two-sided Emiless state of both the filaments F11 and F12, poor contact, abnormally high voltage, and the like. It is configured so that it can be protected from occurring.

A ground 17 is connected between the thyristor SCR1 and the resistor R15, and a capacitor C12 is connected in parallel with the resistor R15. Thyristor SCR
Zener diode (6.2V) between 1 and resistor R15
ZD13, electrolytic capacitor (10μF / 50V) C11
Is connected to the ground 17 via the. Also, the relay R
One side of Y1 is connected to a resistor (3.3 KΩ) R13 and one side of a bidirectional photocoupler PC1 (light receiving side), and the other side of the bidirectional photocoupler PC1 (light receiving side) is connected to ground 17 via a resistor R14. It is connected to the. Note that the resistor R14 is connected in parallel with the electrolytic capacitor C11. D6
Is a rectifying element.

One side of the bidirectional photocoupler PC1 (light emitting side) is connected to one side of a filament F12 provided at the other end of the fluorescent lamp FLR1, and the other side of the bidirectional photocoupler PC1 (light emitting side). Has a pair of Zener diodes (6.2 V) ZD1 connected in series with opposite polarities.
2. It is connected between the resistors R11 and R12 via ZD11. One side of a contact SW1 linked to the relay RY1 is connected between one side of the filament F11 provided at one end of the fluorescent lamp FLR1 and the resistor R11, and the other side of the contact SW1 is connected to the other side of the fluorescent lamp FLR1. It is connected to one side of a filament F12 provided at the end.
That is, the contact SW1 of the relay RY1 is connected in parallel with the fluorescent lamp FLR1. The full-wave rectifier D1 (minus side) and the ground 17 of the control circuit power supply circuit 12 are connected.

When the contact SW1 is operated and closed by the relay RY1, both ends of both filaments F11 and F12 provided at both ends of the fluorescent lamp FLR1 and both ends of the capacitor Cf1 are short-circuited, and both filaments F11 and F1 are shorted.
It is configured to prevent an abnormal current from flowing between the two. The fluorescent lamps FLR1, FLR2,.
The FLR5, the capacitors CS1, CS2,..., CS5, the choke coils CH1, CH2,.
51, resistors R12... R52, contact S of relay RY1
W1, SW2,... Are provided, and each fluorescent lamp FLR is provided.
Anomaly detection and protection circuit 1 for each of 1.
6 are configured to work.

Here, the rectifying action in the single Emiless discharge state will be described in more detail. At the start of lighting of the fluorescent lamp FLR1, the high potential point DH1 (DH2) is stabilized at half (middle point) of the power supply voltage by the alternating current flowing through the fluorescent lamp FLR1. Switching elements FET1 and FET2 have a duty of 50%
Because it is a complete exchange because it is on / off at
The potential at the point H1 is a potential close to a state where the DC current cutting capacitor CS1 is not inserted.

The potential at the point DH1 stabilizes at half the DC voltage of the DC power supply when the fluorescent lamp FLR1 is normally turned on. When any one of the fluorescent lamps FLR1 to FLR5 reaches the end of life (in this case, a single Emiless state), the voltage at the DH1 point changes from half the voltage of the DC power supply due to rectification.
The voltage varies depending on which end of the fluorescent lamp FLR1 at the end of life is in the Emiless state. in this case,
When one end of the fluorescent lamp FLR1 is in the Emiless state, the point DH1 is higher than the normal voltage, and when one of the other ends is in the Emiless state, the voltage is lower than the normal voltage.

That is, the DC current cutting capacitor CS1
The end-of-life tube can be detected by measuring whether the rear side potential (potential at point DH1) is positive or negative with respect to the voltage at the time of normal lighting.
In this case, if the midpoint of the normal lighting of the fluorescent lamp FLR1 is set to the midpoint (0 V) and the detection voltage in the Emiless state is set to ± 8 V or more during the normal lighting, the DH1 point is set when either end becomes the Emiless state. Since the voltage exceeds ± 8 V, the Emiless state can be detected.

Then, the voltage waveform F1 (waveform of the oscillation frequency of the oscillation circuit 14) detected by the abnormality detection / protection circuit 16 as shown in FIG. 3 is divided by the resistors R11 and R12 and reduced to a predetermined voltage. If the lowered voltage does not exceed a predetermined threshold value (set voltage ± 8 V), it is normally turned on. The set voltage (± 8 V) is determined by the Zener diodes ZD12 and ZD11 and the resistors R11 and R12. In this case, the abnormality detection / protection circuit 16 is set to operate when the set voltage becomes about 1.3 times or more the normal lighting voltage.

When one of the filaments F12 is in the Emiless state, a voltage waveform F2 (FIG. 3) is generated, and the abnormality detection / protection circuit 16 detects the DC superimposed high frequency voltage of the high voltage waveform F2. That is, when the detected voltage waveform F2 exceeds, for example, +8 V (upper side of the detected voltage waveform F2), the Zener diodes ZD12, ZD
A current flows through the bidirectional photocoupler PC1 through D11. When the other filament F11 is in the Emiless state, a DC superimposed high-frequency voltage having a waveform inverted upside down from F2 is generated.
2. A current flows through the bidirectional photocoupler PC1 via the ZD11.

That is, the Zener diodes ZD12, ZD
11 and the bidirectional photocoupler PC1 are configured to monitor the voltage in both the positive and negative directions, and to flow a current to the bidirectional photocoupler PC1 when the voltage on the rear side of the capacitor CS1 becomes higher than the set voltage (± 8 V). ing. Thus, the abnormality detection / protection circuit 16 operates the relay RY1 to close the contact SW1. Then, when the contact SW1 of the relay RY1 is closed, both ends of the capacitor Cf1 are short-circuited, so that the fluorescent lamp FLR1 and the capacitor Cf1 are closed.
Does not resonate with the frequency of the oscillation circuit 14, so that no current flows from the inverter output to the fluorescent tube, and abnormal heat generation on the tube wall can be prevented.

Further, in the case of the both Emiless states, an alternating current is generated in the output voltage (current), and the resonance phenomenon continuously appears in the output circuit, so that the voltage of the detecting section rises with the alternating voltage. F3 in FIG. 3 shows a voltage waveform in both the Emiless states. As can be seen from the figure, the output voltage in both Emiless states is ± 8 V
, Current flows to the bidirectional photocoupler PC1 via the Zener diodes ZD12 and ZD11. When a current flows through the bidirectional photocoupler PC1, the abnormality detection / protection circuit 16 operates the relay RY1 to close the contact SW1 of the relay RY1 as in the case of single emission, and prevents abnormal heat generation of the tube wall as in the case of single emission. Can be.

Also, in the case of a contact failure or the like, since the resonance phenomenon appears intermittently in the lamp circuit, the voltage of the detecting section rises with the alternating voltage. F4 in FIG. 3 shows a voltage waveform in a contact failure state. As can be seen from the figure, when the output voltage in the contact failure state intermittently exceeds ± 8 V, the Zener diode Z
The current flowing through the bidirectional photocoupler PC1 via D12 and ZD11 is temporarily stored in the capacitor C11. When a predetermined amount of current is stored in the capacitor C11,
The abnormality detection / protection circuit 16 is a relay R
By operating Y1, the contact SW1 is closed, and abnormal heat generation at a defective contact portion can be prevented.

Next, the operation of the fluorescent lamp lighting device 10 having the above configuration will be described. The noise filter 11 is for preventing a noise component generated by the operation of the fluorescent lamp control device 10 from flowing out to the commercial AC power supply AC.
The noise component is removed by the commercial AC power supply AC using the noise filter 11.
The technique for preventing the spillage from flowing out is known in the art, and a detailed description thereof will be omitted. The power supply circuit 12 for the control circuit is a power supply circuit for operating the start control circuit 13 and the oscillation circuit 14. The start control circuit 13 and the oscillation circuit 14 are driven by the drive circuit 15 so that both switching elements FET1 and FET2 are operated.
Is a circuit for driving the fluorescent lamp FLR1 to drive the fluorescent lamp FLR1. The circuit for lighting the fluorescent lamp FLR1 is a conventionally known technique, and a detailed description thereof will be omitted. In addition, fluorescent lamp FLR1
When lighting, the relay RY1 is not energized, and each fluorescent lamp FLR1 is turned on.
It is assumed that a slim tube having a diameter of 16 mm and a length of 732 mm is used. It is to be noted that the protection circuit 16 operates to prevent the fluorescent lamp from being turned off for about 7 seconds from the start of lighting of the fluorescent lamp to complete lighting.

Then, the commercial AC power supply AC is full-wave rectified by the rectifying / smoothing circuit (full-wave rectifying element D1), and the DC power is input to the high-frequency inverter circuit. In the high-frequency inverter circuit, a high-frequency current of several tens of kilohertz is output from the middle point of the switching elements FET1 and FET2 via the coil L1 by the switching elements FET1 and FET2 which are high-frequency switched by the driving circuit 15, and a plurality of fluorescent lights connected in parallel Load choke coils CH1 to CH5 composed of lamps (5 lamps FLR1 to FLR5) and fluorescent lamps FLR1 to FLR
Current flows through the capacitors Cf1 to Cf5 via the filaments F11, F12,... Of both poles of the LR5. After preheating the filaments F11, F12,... For a predetermined time, the resonance is boosted to the poles of the fluorescent lamps FLR1 to FLR5. A voltage is applied to light the lamp.

When the end-of-tube state (single Emiless state) occurs while the fluorescent lamp FLR1 is on, the abnormality detection / protection circuit 16 detects a high voltage waveform F2 behind the capacitor CS1. As a result, the abnormality detection / protection circuit 16 closes the contact SW1 of the relay RY1, thereby preventing abnormal heat generation of the tube wall. In addition, abnormal states such as the both Emiless state and poor contact can be detected in the same manner, thereby preventing abnormal heat generation on the tube wall and heat generation at the poor contact part.

As described above, the abnormality detection / protection circuit 16
When the DC superimposed high-frequency voltage exceeds a predetermined voltage (± 8 V) set for each of the positive and negative polarities, the two poles of the fluorescent lamp FLR1 are short-circuited. , And abnormal high voltages can be detected. This makes it possible to prevent abnormal heating of the fluorescent lamp FLR1 and the like.

Further, voltage dividing resistors R11 and R12, a pair of Zener diodes ZD12 and ZD11, a bidirectional photocoupler PC1, switching elements FET1 and FET2.
In addition, since the abnormality detection / protection circuit 16 is configured by a simple circuit of the relay RY1 (including the contact SW1), the fluorescent lamp lighting device 10 can be manufactured at low cost and in a small space.

A plurality of series circuits of a current limiting choke coil, a capacitor CS1 for cutting direct current and a fluorescent lamp FLR1 are connected in parallel to the output of the high frequency inverter circuit. Since the fluorescent lamp FLR1 is provided between both electrodes of the tube,
Only the lighting can be stopped. Thus, while the other normal fluorescent lamp FLR1 is continuously lit, the lighting of only the abnormal fluorescent lamp FLR1 can be reliably stopped.

[0041]

As described above in detail, according to the first aspect of the present invention, a current limiting choke coil and a fluorescent tube as a load are connected in series to the output terminal of the high frequency inverter circuit, and the capacitor is connected in parallel with the fluorescent tube. In a multi-light fluorescent lamp lighting device in which a plurality of circuits of the LC resonance lighting method are connected in parallel, a DC current cutting capacitor is inserted in series with the choke coil in the resonance circuit to monitor the voltage generated on the fluorescent tube side. An abnormality detection / protection circuit is provided in each circuit, and the abnormality detection / protection circuit is provided when the DC superimposed high-frequency voltage exceeds at least one of predetermined threshold values set to positive and negative polarities for a predetermined time. In addition, only the circuit exceeding the threshold is short-circuited between the two poles of the fluorescent tube. Both can be detected. As a result, while the normal fluorescent tube maintains normal lighting, the output of only the abnormal load circuit can be cut off, and the power consumption at the time of abnormality can be reduced. Therefore, it is possible to reliably prevent abnormal heat generation in the vicinity of the filament of the fluorescent lamp and abnormal heat generation in the defective contact portion, and to greatly improve the safety of the fluorescent lamp lighting device. It becomes something.

According to the second aspect of the present invention, in addition to the above, the abnormality detecting / protecting circuit includes a voltage dividing resistor for dividing a DC voltage, and a pair of zeners of different polarities connected between the voltage dividing resistors. A series circuit of a diode and a bidirectional photocoupler, a switching element driven by the photocoupler, a relay controlled to be energized by the switching element, and a contact point of a relay connected in parallel between both poles of the fluorescent lamp. Therefore, the fluorescent lamp lighting device can be configured with an extremely simple circuit. This makes it possible to manufacture the fluorescent lamp lighting device at low cost and in a small space. Further, since the fluorescent tube side of the output circuit is short-circuited by the contact point of the relay, the load fluctuation can be minimized. In particular, since the relay is not normally energized, it is possible to contribute to energy saving and to reduce the frequency of opening and closing of the contacts, as compared with a method in which the relay is normally connected at the normal time. Therefore, the contact wear of the relay is small and the reliability of the relay can be greatly improved.

A series circuit of a current limiting choke coil, a capacitor for cutting direct current and a fluorescent lamp is connected in parallel with the output of the high-frequency inverter circuit.
An abnormality detection / protection circuit is provided between both electrodes of each fluorescent tube, so that an abnormal fluorescent lamp can be turned off and other normal fluorescent lamps can be kept on as it is. Become. As a result, load fluctuations are reduced and fluctuations in the brightness of the fluorescent lamp are almost eliminated. Therefore,
The convenience of the fluorescent lamp lighting device can be greatly improved.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram of a fluorescent lamp control device according to the present invention.

FIG. 2 is a diagram showing a state where an abnormality detection / protection circuit is connected to a fluorescent lamp.

FIG. 3 is a diagram illustrating a relationship between a voltage waveform during normal lighting, a voltage waveform during one-sided emission, a voltage waveform during both-sided emission, and a voltage waveform during a poor contact detected by an abnormality detection / protection circuit ( 55KZz high-frequency component envelope waveform diagram).

[Explanation of symbols]

 Reference Signs List 10 fluorescent lamp control device 11 noise filter 12 power supply circuit for control circuit 13 start control circuit 14 oscillation circuit 15 drive circuit 16 abnormality detection / protection circuit C11 electrolytic capacitor C12 capacitor Cf1 capacitor CS1 capacitor CH1 choke coil D6 rectifier element FET2 switching element FET1 switching Element FLR1 Fluorescent lamp F11 Filament F12 Filament R11 Resistance R12 Resistance R13 Resistance R14 Resistance R15 Resistance PC1 Bidirectional photo coupler RY1 Relay SW1 Contact SCR1 Thyristor ZD11 Zener diode ZD12 Zener diode ZD13 Zener diode

Continued on the front page (72) Inventor Wataru Kanai 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Shigeo Matsuzawa 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Inside Sanyo Electric Co., Ltd. (72) Inventor Moriyuki Obatake, 906-6 Oyagi-cho, Takasaki-shi, Gunma Co., Ltd. Inside (72) Inventor Noboru Kawaura No. 906-6, Oyagi-cho, Takasaki-shi, Gunma Co., Ltd. F term (reference) 3K072 AA02 AB02 BB01 BC01 DB03 DC07 DD04 EA01 EA07 EB05 FA05 GA02 GB12 GC04 HA02

Claims (2)

[Claims] An output terminal of a high-frequency inverter circuit is connected in series with a current limiting choke coil (L) and a fluorescent tube as a load, and is connected to a capacitor (C) connected in parallel with the fluorescent tube.
In a multi-lamp fluorescent lamp lighting device in which a plurality of circuits of the C resonance lighting system are connected in parallel, a DC current cutting capacitor is inserted in series with a choke coil in the resonance circuit to monitor a voltage generated on the fluorescent tube side. An abnormality detection / protection circuit provided in each circuit, the abnormality detection / protection circuit is provided when the monitoring point voltage exceeds at least one of predetermined thresholds set to positive and negative polarities respectively. , Only circuits that exceed the threshold,
A fluorescent lamp lighting device, characterized in that both electrodes of the fluorescent tube are short-circuited. 2. An abnormality detection / protection circuit includes: a voltage dividing resistor for dividing a monitoring point voltage; a series circuit of a pair of zener diodes having different polarities and a bidirectional photocoupler connected between the voltage dividing resistors; 2. The fluorescent lamp according to claim 1, further comprising: a relay that is energized and controlled when a photocoupler output continues for a predetermined time; and a contact of said relay connected in parallel between both poles of the fluorescent tube. Lighting device.