JP2002289381A - Discharge lamp lighting device and lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide electric discharge lamp lighting equipment, which can perform deep dimming of light properly without making output voltage high. SOLUTION: High frequency electric power from an inverter circuit, which converts direct-current electric power into high frequency electric power and carries out high frequency lighting of the electric discharge lamp, is impressed almost equally to the electric discharge lamps connected in parallel through balancers. A control circuit 5 performs frequency control of the inverter circuit so that difference of load current of the electric discharge lamps 4a and 4b connected in parallel and detected by a differential load current detecting circuit may be zero. Thereby, deep dimming of light becomes possible without making output voltage of the inverter circuit high.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device and a lighting device having a function of lighting a discharge lamp with high frequency power and performing deep dimming.

[0002]

2. Description of the Related Art Generally, a discharge lamp device for lighting a discharge lamp such as a fluorescent lamp converts DC into high-frequency AC power by an inverter circuit and lights the discharge lamp at high frequency. When dimming is performed, the frequency is increased by an inverter circuit to reduce the load power at the time of lighting, and the dimming is deepened.

FIG. 4 is a configuration diagram showing an example of a conventional discharge lamp lighting device having a dimming function. The DC power from the DC power supply 1 is supplied to the switching elements 2a, 2
By the on / off control of b, the ballast L1 and the resonance capacitor C1 forming the resonance circuit are input. Then, the balancer 3 and the DC cut capacitors C2a, C2b
Is input to each of the discharge lamps 4a and 4b connected in parallel via the controller, and turns on the discharge lamps 4a and 4b. Balancer 3
Is for equalizing the voltage applied to the discharge lamps 4a and 4b connected in parallel.

A dimming signal is input to a control circuit 5, and dimming is performed based on the dimming signal. In this case, the control circuit 5
The current detector 6 detects the current flowing through the switching elements 2a and 2b of the inverter circuit,
Control is performed so that the current flowing through a and 2b becomes a current corresponding to the dimming signal.

[0005]

However, in such a conventional discharge lamp lighting device, when dimming is performed, the current of the switching element is controlled to be a current corresponding to the dimming signal. In particular, when deep light control is performed, proper light control cannot be performed. That is, the current flowing through the switching elements 2a and 2b is the discharge lamps 4a and 4b which are loads.
When the current is small, such as during deep dimming, the current flowing through the switching elements 2a and 2b may be controlled based on the dimming signal. As a result, the ratio of the current flowing through the resonance capacitor C1 increases, and a current corresponding to the dimming signal cannot flow through the discharge lamps 4a and 4b.

For this reason, for example, when two Hf32W fluorescent lamps are turned on, a dimming of 3 to 5% has been confirmed by experiments. However, a dimming of 1% or less or a vicinity thereof for achieving a further lighting effect is achieved. Light had its limits.

Therefore, the discharge lamps 4a, 4b connected in parallel are
It is conceivable to detect the sum of the currents flowing through the lamps and control the current to be a current corresponding to the dimming signal. As a result, twice the current flows through the remaining one discharge lamp.

In order to eliminate the drawback of the parallel connection, as shown in FIG. 5, the discharge lamps 4a and 4b are connected in series to detect the current flowing through the discharge lamps 4a and 4b, and the current is used as a dimming signal. There is a discharge lamp lighting device adapted to have a corresponding current.

In this case, since the current flowing through the discharge lamps 4a and 4b is fed back, it is possible to dimm less than or equal to 1% or less in order to produce an effect. 4b are connected in series, the output voltage of the inverter circuit increases, and there is a danger of electric shock.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a discharge lamp lighting device and a lighting device capable of appropriately performing deep dimming without increasing the output voltage.

[0011]

According to a first aspect of the present invention, there is provided a discharge lamp lighting device, comprising: an inverter circuit for converting DC power into high frequency power and lighting the discharge lamp at high frequency; and high frequency power from the inverter circuit connected in parallel. A load current difference detection circuit for detecting a difference between load currents of the discharge lamps connected in parallel; and a load current difference detected by the load current difference detection circuit being zero. A control circuit for controlling the frequency of the inverter circuit.

In the present invention and the following inventions, definitions and technical meanings of terms are as follows unless otherwise specified.

The inverter circuit has one or two switching elements, and converts DC power into high-frequency AC power by turning on and off the switching elements. As the DC power, any of DC power obtained by rectifying commercial AC power with a rectifier can be used in addition to direct input from a DC power supply. The high-frequency power from the inverter circuit generates a starting voltage of the discharge lamp by resonance in a resonance circuit formed by a ballast inductor and a capacitor.

The high frequency power from the inverter circuit is applied to the discharge lamps connected in parallel almost uniformly via a balancer. Then, the load current difference detection circuit detects a difference between the load currents of the discharge lamps connected in parallel. The load current difference detection circuit prepares, for example, windings of opposite polarities corresponding to the respective discharge lamps connected in parallel to the primary side of the transformer, and supplies the load current of each discharge lamp to the primary windings. It is configured to detect the difference current between the load currents of the respective discharge lamps from the secondary winding.

The control circuit controls the frequency of the inverter circuit so that the load current difference detected by the load current difference detection circuit becomes zero. In particular, when a light control signal is input, a load current corresponding to the light control signal is supplied to the discharge lamp.

According to the present invention, since the output of the inverter circuit is controlled so that the load currents of the discharge lamps connected in parallel are equal, the dimming can be made deep without increasing the output voltage of the inverter circuit. Also, the load current of the discharge lamp can be properly adjusted. Therefore, it is also possible to adjust the light intensity to 1% or less for producing the lighting effect.

According to a second aspect of the present invention, there is provided a discharge lamp lighting device,
The invention according to claim 1, further comprising a filament preheating circuit that cuts off preheating of the filament of the discharge lamp when the discharge lamp is in full light, and preheats the filament of the discharge lamp during dimming.

According to the present invention, when dimming is performed, the filament of the discharge lamp is preheated so that the discharge lamp can be properly lit.

The control circuit supplies the preheating power from the filament preheating circuit to the area where preheating is required in the dimming state when dimming the discharge lamp, while supplying the preheating power when the discharge lamp is full light. To stop.

Thus, at the time of dimming which requires preheating of the filament, it is possible to supply filament preheating electric power in conformity with the dimming state. Further, when the filament preheating is not required as in the case of full discharge of the discharge lamp, the preheating is cut off, so that the preheating power can be saved.

According to a third aspect of the present invention, there is provided an illuminating device comprising: the discharge lamp lighting device according to the first or second aspect; and a fixture main body to which the discharge lamp lighting device is mounted.

According to the present invention, the lighting apparatus having the effects of the first and second aspects of the present invention is equipped with the apparatus main body and the discharge lamp lighting device of the first or second aspect mounted on the apparatus main body. Can be provided.

[0023]

Embodiments of the present invention will be described below. FIG. 1 is a configuration diagram of a discharge lamp lighting device according to a first embodiment of the present invention.

The DC power from the DC power supply 1 is input to a ballast L1 and a resonance capacitor C1 forming a resonance circuit by ON / OFF control of two switching elements 2a and 2b of the inverter circuit. That is, the high-frequency power from the inverter circuit is resonated in the resonance circuit formed by the ballast L1 and the resonance capacitor C1, and the discharge lamps 4a, 4a
The starting voltage of b is generated.

The load circuit is provided with a balancer 3, and high-frequency power is applied to the two discharge lamps 4a and 4b connected in parallel almost uniformly via DC cut capacitors C2a and C2b, respectively. Thereby, the respective discharge lamps 4a and 4b connected in parallel are turned on.

The load current difference detection circuit 7 detects a difference between load currents of the discharge lamps 4a and 4b connected in parallel. That is, as the load current difference detection circuit 7, windings 8a and 8b through which the load current of each of the discharge lamps 4a and 4b connected in parallel to the primary side of the transformer are provided, and these windings 8a and 8b have opposite polarities. It is connected.

Accordingly, a voltage proportional to the difference between the load currents flowing through the primary windings 8a and 8b is detected in the secondary winding 9 of the transformer, and after being rectified by the rectifier 10, the operational amplifier 1
1 to the control circuit 5.

The control circuit 5 controls the switching elements 2a and 2b of the inverter circuit so that the difference between the load currents of the discharge lamps 4a and 4b connected in parallel during all light and dimming becomes zero.
2b to output a control signal. In particular, at the time of dimming, the frequency of the inverter circuit is controlled so that a load current corresponding to the dimming signal flows through the discharge lamps 4a and 4b.

Therefore, the discharge lamps 4a, 4b connected in parallel
, The same load current flows, so that dimming is performed almost equally. Also, the detected load current does not include the current shunted to the resonance capacitor C1 of the resonance circuit, so that appropriate deep dimming can be performed. As a result, it is also possible to adjust the light intensity to 1% or less or a value close to 1% for producing an effect.

In the above description, the output voltage of the inverter circuit is directly input to the load circuit. However, it is needless to say that a constant voltage control circuit such as a boost chopper circuit may be provided.

As described above, according to the first embodiment, the load current of the discharge lamps 4a and 4b connected in parallel is determined based on the difference between the load currents detected by the load current difference detection circuit 7. Since the output of the inverter circuit is controlled to be equal, the load current of the discharge lamp can be appropriately adjusted even when the dimming is deepened. Therefore, it is also possible to adjust the light intensity to 1% or less or a vicinity thereof for producing an effect.

Next, a second embodiment of the present invention will be described. FIG. 2 is a configuration diagram of a discharge lamp lighting device according to a second embodiment of the present invention. This second embodiment is different from the first embodiment shown in FIG. 1 in that the preheating of the filaments of the discharge lamps 4a and 4b is cut when the discharge lamp is full light, and the discharge lamps 4a and The filament preheating circuit 12 for preheating the filament 4b is additionally provided. The other configuration is the same as that of the first embodiment shown in FIG. 1, and therefore, the same components are denoted by the same reference numerals and overlapping description will be omitted.

In FIG. 2, the filament preheating circuit 12
Is configured by connecting a preheating transformer 13 in parallel with the inverter circuit, and the filaments of the discharge lamps 4a and 4b are connected to the secondary winding of the preheating transformer 13. A DC cut capacitor C2c and a switch S are connected to the preheating transformer 13, and when the discharge lamps 4a and 4b do not need preheating as in the case of full light, the switch S is turned off to prevent preheating. I have.

That is, when the discharge lamps 4a and 4b are dimmed by the inverter circuit, the control circuit 5 turns on the switch S and preheats to a region where preheating is required in the dimmed state. On the other hand, in a region where the filament temperature in the entire light region is high and preheating is unnecessary, the switch S is turned off to cut off the preheating.

This makes it possible to satisfy the lamp life at the time of dimming and to prevent preheating when preheating is not required, so that useless preheating power can be saved.

The discharge lamp lighting device configured as described above is mounted on the fixture body 14 to form a lighting device, as shown in FIG. That is, the discharge lamp lighting device is the appliance body 1.
The discharge lamps 4a and 4b are housed inside
To form an illumination device. According to this lighting device, since the process of adjusting the output is simplified, the cost of the entire lighting device can be reduced.

[0037]

According to the present invention, since the output of the inverter circuit is controlled so that the load currents of the discharge lamps connected in parallel become equal, the dimming can be deepened without increasing the output voltage of the inverter circuit. In such a case, the load current of the discharge lamp can be appropriately adjusted. Therefore, it is also possible to adjust the light intensity to 1% or less or a vicinity thereof for producing an effect.

Thus, at the time of dimming in which filament preheating is required, filament preheating power can be supplied in conformity with the dimming state. Further, when the filament preheating is not required as in the case of full discharge of the discharge lamp, the preheating is cut off, so that the preheating power can be saved.

According to the present invention, the lighting apparatus having the effects of the first and second aspects of the present invention is provided with the apparatus main body and the discharge lamp lighting device of the first or second aspect provided in the apparatus main body. Can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a discharge lamp lighting device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a discharge lamp lighting device according to a second embodiment of the present invention.

FIG. 3 is a perspective view showing an example of a lighting device according to the embodiment of the present invention.

FIG. 4 is a configuration diagram showing an example of a conventional discharge lamp lighting device having a dimming function.

FIG. 5 is a configuration diagram showing another example of a conventional discharge lamp lighting device having a dimming function.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 DC power supply 2 Switching element 3 Balancer 4 Discharge lamp 5 Control circuit 6 Current detector 7
Load current difference detection circuit, 8: primary winding, 9: secondary winding,
10 rectifier, 11 operational amplifier, 12 filament preheating circuit, 13 transformer for preheating, 14 instrument body

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3K072 AA01 AA02 AB02 BA03 BC01 BC03 DD04 DE02 DE07 GB12 GC04 HA06 3K098 CC41 CC56 DD22 DD37 EE03 EE13 EE14 EE35

Claims (3)

[Claims] 1. An inverter circuit for converting DC power into high-frequency power and lighting a discharge lamp at high frequency; a balancer for applying high-frequency power from the inverter circuit to the discharge lamps connected in parallel; and a discharger connected in parallel. A load current difference detection circuit for detecting a difference between load currents of the lamps; and a control circuit for controlling the frequency of the inverter circuit so that the difference between the load currents detected by the load current difference detection circuit becomes zero. A discharge lamp lighting device. 2. A filament preheating circuit which cuts off preheating of a filament of the discharge lamp when the discharge lamp is in full light, and preheats a filament of the discharge lamp when dimming. The discharge lamp lighting device as described in the above. 3. A lighting device, comprising: the discharge lamp lighting device according to claim 1; and a fixture main body to which the discharge lamp lighting device is mounted.