JPH06151083A - Fluorescent lamp lighting device - Google Patents

Abstract

PURPOSE:To provide a fluorescent lamp lighting device allowing stable light control. CONSTITUTION:A fluorescent lamp lighting device is provided with an inverter circuit 10 for converting + or -130V DC voltage obtained by voltage-doubling and rectifying a commercial power source 2 into a high frequency voltage; five fluorescent lamps L1... connected to the inverter circuit 10 through respective current limiting inductances CH1...; and capacitors Cf1... connected to the non-power source side of the filament FL of each fluorescent lamp in parallel to the fluorescent lamp. This device is a multiple lamp (five) fluorescent lamp lighting device for lighting by the resonance action of each series resonance circuit formed of the current limiting inductances CH1... and the capacitors Cf1.... The inverter circuit 10 is internally provided with a first oscillating circuit for high frequency output; a control circuit 12 for temporarily increasing the operation frequency f1 of the high frequency output during the operation of the first oscillating circuit and controlling it to get close to the resonance frequency fo of the series resonance circuit; and a second oscillating circuit 13 for periodically conducting the ON/OFF control of the first oscillating circuit and the modulating work of the control circuit 12.

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 having a dimming function, and more specifically, intermittently outputs while changing the operating frequency of the high frequency output of the inverter circuit of the resonance type fluorescent lamp lighting device. Thus, the present invention relates to a fluorescent lamp lighting device configured to perform dimming while maintaining stable lighting.

[0002]

2. Description of the Related Art In recent years, the use of inverters for fluorescent lighting devices has progressed rapidly, and it has become possible to reduce the flicker of light, which has been a problem of conventional fluorescent lighting devices, improve efficiency, and reduce the size and weight. There is still a strong sense of widespread use of fluorescent lamp lighting devices having a function of adjusting the amount of light of a lamp, a so-called dimming function.

In order to dimming a fluorescent lamp, the current (tube current) flowing through the fluorescent lamp is finally reduced to perform dimming.

As means for this light control, in the inverter lighting device, (1) a frequency control system in which the operating frequency of the inverter circuit is increased and the tube current is reduced by the action of a current limiting inductance. (2) The operating frequency is fixed,
A pulse width control method that reduces the on-time of one pulse of the switching element. In addition, (3) a method has been devised in which the operating frequency is fixed, the output of the inverter circuit is intermittently made intermittent, and the average current value of the tube current is reduced to perform dimming.

FIG. 4 is an example of a circuit diagram of a fluorescent lamp lighting device 1 having a dimming function by the frequency control method of the above (1).
The operation of this circuit will be outlined below.

In FIG. 4, the fluorescent lamp lighting device 1 is D1,
A full-wave voltage doubler rectifier circuit composed of D2, C1, and C2 forms a DC power supply of ± 130 V, and switching elements Q1 and Q2 are connected in series to this. The drive circuits 7 and 8 for alternately driving the switching elements Q1 and Q2 are synchronized with the oscillation frequency f1 of the oscillation circuit 4. The fluorescent lamp 20 constitutes the load circuit 5 together with the series resonance circuit including the current limiting inductance CHo and the capacitor Co.

When a 100 V commercial power source (50/60 Hz) 2 is turned on, a signal is sent to the start circuit 3 through the resistor R1, and the oscillation circuit 4 is set to a high frequency higher than the resonance frequency fo of the series resonance circuit for a predetermined time. The operating frequency is controlled to preheat the fluorescent lamp filament FL. After that, the sweep is gradually performed up to the fundamental frequency fa at the time of normal lighting, which is lower than the resonance frequency fo, and during that period, discharge is started at a frequency slightly higher than the resonance frequency fo, and lighting is performed. After lighting, the fluorescent lamp applied voltage is dumped by the tube current iR, and the lamp is operated so as to be in a normal lighting state (all lights) at a low voltage having a constant frequency fa lower than fo.

For dimming, a variable resistor V that changes the oscillation frequency f1 of the oscillation circuit 4 by the external signal S via the frequency control circuit 6 is used.
Adjust R accordingly. That is, the oscillation frequency f1 (= inverter operating frequency) is swept to a region (hereinafter also referred to as a high region) higher than the resonance frequency fo, and the tube current iR is reduced by the current limiting action of the current limiting inductance CHo. In addition, once the dimming is turned on, resonance does not occur,
It is necessary to sweep to a high region without applying an overvoltage.

Next, the pulse width control method of (2) is set so that both of the two switching elements in the inverter circuit are OFF time width (to prevent a large current from flowing when both are ON. ) Is set larger than usual to reduce the inverter output supply energy and dimming.

The above-mentioned pulse width control method is also called a rest time method and is a general method as a switching power supply, but as a fluorescent lamp lighting device, it is a measure against stripe patterns (uneven light emission) that originally occur in a low temperature environment. It was devised for this purpose and utilizes a high second vibration wave generated by narrowing the pulse width.

Next, the intermittent output method of (3) in which the operating frequency of the inverter circuit is fixed, its output is intermittently intermittently adjusted to reduce the average current value of the tube current, and dimming is performed, The duty of the oscillation state and the stop state of the inverter is adjusted by adding an appropriate circuit for controlling the oscillation ON / OFF. For example, the fluorescent lamp is discharged by repeating oscillation / stop of the oscillation circuit every 0.5 ms. Intermittently, the average light amount is halved as a whole and dimming is performed. In this case, the blinking is repeated at 1 KHz, but at several hundreds Hz or higher, there is no flicker visually and it is felt as a uniform light flux.

[0012]

However, in the frequency control method (1) in which the output oscillation frequency of the inverter circuit is increased and the tube current is decreased by the action of the current limiting inductance, the tube control is generally performed in response to frequency changes in a high region. Since the decrease of the current is slow, it is difficult to perform sufficient dimming, and it is difficult to maintain an appropriate current flowing through the filament FL because the current flowing through the capacitor Co cannot be ignored. Further, there is a problem that the voltage applied to the filament FL becomes high and the life of the fluorescent lamp is shortened.

The pulse width control method (2) can be used as a light control means for a single lamp, but when it is used for multiple lights, the heat and noise of the switching element cannot be ignored, and the light control for multiple lights is performed. It is unsuitable as a system and lacks versatility.

In the intermittent output method (3),
The tube current iR periodically becomes close to zero at several hundreds Hz to several KHz, and relighting is repeated. However, if the tube applied voltage necessary for proper preheating and discharge initiation is not given, it will go out without relighting. There is a great risk of it getting lost. Therefore, the operating frequency must be set to a value sufficiently close to the resonance frequency to reliably apply a high voltage, but in this case the life of the filament is shortened.

Therefore, as preheating for re-lighting, an appropriate average filament current is maintained, an appropriate tube applied voltage (300 to 400 V) and an appropriate application time (0.2 ms).
It is indispensable for stable lighting to give a certain level) and to maintain and secure the tube current after lighting to some extent. However, in the lighted state, the tube applied voltage of 300 to 400 V does not actually occur due to the damper action of the fluorescent tube.

The above problem of extinguishing prevention is understood as an improvement in the limit of stable lighting (reduction voltage characteristic) when the power source is reduced in voltage for some reason, and an improvement in the limit of stable lighting (low temperature characteristic) in a low temperature environment. To be done.

In this respect, in the above-described conventional dimming type fluorescent lamp lighting devices, is it necessary to periodically apply a high voltage to the load circuit in order to solve the problem of extinguishing during full lighting and dimming? In some cases, a large current is passed to improve the lighting sustainability. However, when a high voltage is applied or a large current is applied, the protection circuit such as the heating prevention circuit becomes complicated and the cost increases.

The present invention has been made in view of the above circumstances, and adopts a new dimming means, does not require a special protection circuit, and is capable of maintaining stable lighting both in terms of voltage reduction characteristics and low temperature characteristics. A fluorescent lamp lighting device having an optical function is provided.

[0019]

SUMMARY OF THE INVENTION The present invention provides an inverter circuit for converting a DC voltage into a high frequency voltage, a fluorescent lamp connected to the inverter circuit via a current limiting inductance, and a non-power source side of a filament of the fluorescent lamp. In a fluorescent lamp lighting device comprising a fluorescent lamp and a capacitor connected in parallel, and lighting by the resonance action of a series resonant circuit configured by the current limiting inductance and the capacitor, a first high frequency output for the inverter circuit. An oscillating circuit, a control circuit for temporarily increasing the operating frequency of the high-frequency output during operation of the first oscillating circuit so as to approach the resonant frequency of the series resonant circuit, and turning on the first oscillating circuit. A second oscillating circuit that periodically performs ON / OFF control and the operation of the control circuit, and intermittently outputs while changing the operating frequency of the high frequency output. It is intended to achieve the above object by providing a fluorescent lamp lighting apparatus according to claim more dimmable and the possible.

[0020]

In the fluorescent lamp lighting device according to the present invention, the first oscillation circuit is, for example, a CR oscillation circuit, and the oscillation frequency is directly modulated by the variable resistor. The first oscillating circuit determines the operating frequency of the lighting device through the drive circuit of the switching element.

The second oscillating circuit determines the cycle and duty of the intermittent operation during dimming, and also provides a signal for driving the pulse generating circuit during full lighting and dimming.

The pulse generating circuit as the control circuit performs the function of controlling the variable resistor by using the pulse width and the pulse potential as parameters for the modulation for making the resonance state for the relighting operation. That is, the variable resistance of the first oscillator circuit is gradually swept by the pulse output through the integrating circuit, and the operating frequency f
1 is controlled to approach the resonance frequency fo and return. On this occasion,
The pulse potential determines the depth of modulation, that is, the maximum frequency fb,
The pulse width mainly determines the time of the voltage applied to the tube, which is necessary for the discharge for relighting.

[0023]

Embodiments of the present invention will be described with reference to FIGS.

FIG. 1 is a circuit diagram of a fluorescent lamp lighting device according to the present invention. This lighting device includes an inverter circuit 10 for converting a ± 130V DC voltage obtained by rectifying a 100V commercial power source 2 into a high frequency voltage, and five inverter circuits 10 connected to the inverter circuit 10 through current limiting inductances CH1. Fluorescent lamps L1 ..., and capacitors Cf1 ... Connected in parallel with the fluorescent lamps on the non-power supply side of the filaments FL of the fluorescent lamps.
Is a multi-lamp (five) fluorescent lamp lighting device that is lit by the resonance action of each series resonant circuit configured by the current limiting inductances CH1 ... And the capacitors Cf1. A first oscillator circuit 11 for high frequency output, and a control circuit for temporarily increasing the operating frequency f1 of the high frequency output during operation of the first oscillator circuit so as to approach the resonance frequency fo of the series resonant circuit. 1
2 and a second oscillation circuit 13 that periodically performs ON / OFF control of the first oscillation circuit 11 and the modulation action of the control circuit 12.

The circuit operation will be further described in detail.
Double voltage rectification of 0V commercial power supply 2 ± 13 for C1 and C2
A 0 V DC power supply is made, and power MOSFETs Q1 and Q2 of switching elements are connected in series to the ± terminals of the power supply, and a high frequency power supply is obtained from the midpoint A thereof. Five FL35SS fluorescent lamps are connected in parallel via a current limiting inductance CH1 ... Connected in series as a load of a lighting device at the midpoint A of Q1 and Q2, and the other end of the fluorescent lamp is connected via a commutation capacitor C3. Connected to a 0V power supply.

Further, starting capacitors Cf1 ... Are connected in parallel to the non-power source side of the filament FL of each fluorescent lamp, and each CH and Cf form a series resonance circuit.

The lighting method is a resonance lighting method in which a high voltage is applied by utilizing the resonance action of the series resonance circuit,
The resonance characteristics of the filament current iF and the tube applied voltage Vc with respect to the operating frequency f1 of the high frequency power source in the fluorescent lamp lighting device are shown in FIG.

In this embodiment, the current limiting inductance CH
1 ... 1000 μH, capacitor Cf1 ... 0.005
When set to 6 μF, the resonance frequency fo of the series resonance circuit composed of each CH and Cf is 67.3 KHz.

When the power is turned on, a signal is sent to the start circuit 3 through the starting resistor R1 and the first oscillation circuit 1
1 is controlled to a constant frequency of about 90 KHz for a certain period of time to preheat the fluorescent lamp filament FL, and then gradually swept to a fundamental frequency fa lower than the resonance frequency fo and becomes stable. As for lighting, the arc discharge start voltage is reached around 77 KHz before reaching the resonance frequency fo, and lighting is performed.

After lighting, the tube current i is generated by the arc discharge.
R flows, the voltage is dumped, and the resonance phenomenon disappears. The frequency characteristic of the tube applied voltage Vc shows a downward sloping characteristic due to the current limiting action of the current limiting inductances CH1.

Next, in the fluorescent lamp lighting device according to the present invention, when at least one of the fluorescent lamps is extinguished for some reason in order to improve the voltage reduction characteristics and the low temperature characteristics during full lighting and dimming. In addition, it is configured to immediately resonate and perform relighting operation.

The relighting operation for maintaining stable lighting during all lighting will be described below.

In FIG. 2, (a) shows the second oscillator circuit 1.
3 is an oscillating voltage waveform and is set to a 1 ms cycle. (B) is an output voltage oscillation waveform of the pulse generation circuit of the control circuit 12, and the effective pulse signal 16 of 0.15 ms is generated in synchronization with the rising of (a). (C)
Shows the change over time in the operating frequency (= oscillation frequency of the first oscillation circuit 11) f1 during all lighting. As can be seen from the graph, the fundamental frequency fa is set to 45 KHz, which is a region lower than the resonance frequency fo, and the operating frequency f is temporarily set in a cycle of 1 ms.
1 according to the output voltage of the control circuit 12
By changing the variable resistance VR of 1, the maximum modulation depth fb is gradually modulated up to 56 KHz.

At this time, the first oscillation circuit 11 is, for example, a CR
The oscillation frequency f1 is generated by the variable resistor VR.
Is directly modulated. The first oscillating circuit 11 determines the operating frequency f1 through the driving circuits 7 and 8 for switching elements.

The second oscillating circuit 13 gives a signal for driving the pulse generating circuit 12 at the time of full lighting and at the time of dimming.

The pulse generating circuit 12 as a control circuit continuously controls the variable resistor VR for the modulation for the relighting operation using the pulse width and the pulse potential as parameters. That is, the rectangular pulse output is repeatedly charged and discharged through the integrating circuit composed of R2 and C4, and gradually rises to 0.15 ms.
After that, the control signal gradually falls, and the variable resistance VR of the first oscillation circuit is continuously swept to bring the operating frequency f1 close to the resonance frequency fo and perform control for returning.

The modulation control of the operating frequency to a temporary resonance state is performed by the filament FL required for resonance relighting.
The average filament current for supplying sufficient preheating, the tube applied voltage Vc and the application time are set.

Next, the dimming means during dimming and the relighting operation for maintaining stable lighting will be described.

The dimming is performed by the external signal S, the switches SW1 and SW2 are closed when the signal comes, and the rectangular oscillatory wave (a) of the 1 ms cycle of the second oscillating circuit 13 causes the dimming as shown in FIG. The inverter output is intermittently output at a cycle of 1 ms (0.5 ms oscillation, 0.5 ms stop), and the blinking is 1K.
Performing at Hz halves the amount of light as a whole.
In this case, the re-lighting operation is repeated at 1 KHz, but at several hundreds Hz or higher, there is no flicker visually, and it is perceived as a uniform change of the luminous flux, as in the conventional intermittent output method.

On the other hand, at the time of dimming, as can be seen from FIG. 2D, after raising the operating frequency f1 from the predetermined basic frequency fc in the low region to fd (where fo> fd) during the inverter output period, Modulation is performed to gradually return to the original fc. Therefore, as in the case of all the lights, the resonance state is automatically approached temporarily and the lights are re-lighted, and there is no fear of extinction during dimming, and stable lighting is maintained.

That is, as can be seen from the graph, the fundamental frequency f
c is set to 50 KHz which is lower than the resonance frequency fo, and 1 m
By changing the variable resistance VR of the first oscillation circuit 11 according to the output voltage of the control circuit 12 during the output period of 0.5 ms in the cycle of s, the maximum modulation depth fd is gradually increased to 59 KHz. To. At this time, since the average current value is reduced due to the intermittent output, fc
And fd are set to the resonance frequency fo rather than the corresponding fa and fb at the time of all lights, so as to ensure a sufficient average filament preheating current at the time of relighting and the tube applied voltage and application time at the time of resonance to ensure relighting. It is set a little closer. However, since it is not always in the resonance state during the output period,
There is no risk of shortening the life of the filament FL.

The SW2 is forcibly opened by the start circuit 3 to invalidate the dimming operation so that the initial lighting operation works properly even if the dimming signal S is output when the power is first turned on. It is a switch provided for this purpose.

Further, as described above, the output of the pulse generating circuit works to control the variable resistor VR gradually by repeating charging and discharging in the integrating circuit of R2 and C4 both during full lighting and during dimming. The tube applied voltage time required for lighting can be set by appropriately adjusting the values of R2 and C4.

According to the test by the present inventor, the FL35S, which has a fixed pulse width and pulse potential and is capable of dimming in one step of dimming
This fluorescent lamp lighting device uses five S fluorescent lamps as a load.
It was found that dimming of 43% was possible and power consumption was reduced by about 40%.

Needless to say, dimming is possible by continuously changing the duty of the inverter output time and the stop time in the intermittent output.

However, since the average filament current value also changes, it is also necessary to control the modulation depth (frequency displacement) and set an appropriate filament current and an appropriate tube applied voltage in accordance with the duty.

In addition, as a reminder, the power supply circuit system, the inverter circuit system, and the number of fluorescent lamps used in the fluorescent lamp lighting device according to the present invention are not limited to those in the above-described embodiment, and inverter resonance lighting is used. It goes without saying that various other systems and different numbers of fluorescent lamps may be used as long as they are systems, and the dimming function disclosed by the present invention can be applied.

[0048]

Since the fluorescent lamp lighting device according to the present invention is constructed as described above, it has the following effects.

(1) It has an excellent effect of obtaining a stable dimming function with excellent voltage reduction characteristics and low temperature characteristics.

(2) Since the relighting operation is performed without passing through the resonance point, the fluorescent lamp and the inverter circuit are less deteriorated, and the life of the fluorescent lamp lighting device is extended, which is an excellent effect.

[Brief description of drawings]

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

FIG. 2 is an oscillation frequency change diagram of the oscillator 1 when (A) all lights and (B) dimming.

FIG. 3 Frequency dependence of filament current and tube applied voltage near resonance frequency

FIG. 4 is a circuit diagram of a conventional fluorescent lamp lighting device having a frequency control type dimming function.

[Explanation of symbols]

 1 Inverter Circuit 2 Commercial Power Supply 3 Start Circuit 4 Oscillation Circuit 5 Load Circuit 6 Frequency Control Circuit 7, 8 Drive Circuit 10 Inverter Circuit 11 First Oscillation Circuit 12 (Modulation) Control Circuit 13 Second Oscillation Circuit 16 Effective Pulse Signal S Dimming signal L1, ... Fluorescent lamp CH1, ... Current limiting inductance Cf1, ... Capacitor 20 Fluorescent lamp FL filament iF Filament current iR Tube current Vc Tube applied voltage Q1, Q2 Switching element VR (for oscillation frequency modulation) Variable resistance FL filament SW1 Dimming switch SW2 Oscillation intermittent switch f1 Operating frequency fo Resonant frequency

Claims (1)

[Claims] 1. An inverter circuit for converting a DC voltage into a high frequency voltage, a fluorescent lamp connected to the inverter circuit via a current limiting inductance, and a capacitor connected in parallel with the fluorescent lamp on the non-power source side of the filament of the fluorescent lamp. And
In a fluorescent lamp lighting device that lights up by the resonance action of a series resonance circuit composed of the current limiting inductance and a capacitor, a first oscillation circuit for high frequency output in the inverter circuit and a first oscillation circuit during operation. A control circuit for temporarily increasing the operating frequency of the high-frequency output so as to approach the resonance frequency of the series resonance circuit, ON / OFF control of the first oscillation circuit, and the operation of the control circuit periodically. And a second oscillating circuit for performing the dimming control by intermittently outputting the high frequency output while changing the operating frequency of the high frequency output.