JPH07153584A - Stable circuit for low-pressure discharge lamp - Google Patents

Abstract

PURPOSE: To appropriately start a low-pressure discharge lamp under all conditions including a high-temperature restarting condition by providing a ballast circuit additionally comprising a voltage-sensitive bidirectional electronic switch connected in series to an element having a positive temperature coefficient(PTC). CONSTITUTION: A low-frequency input passes through a full-wave bridge rectifier 14 or the like, is converted into a high-frequency alternating current in a high-frequency inverter circuit 30, and then, passes a ballast impedance including a feedback transformer 32 and a resonance ballast inductor 34, thereby setting appropriate starting/operating power value to be applied to a lamp 12. A bidirectional electronic switch 60 is connected in series to a PIC element 64 in an electrothermal preheating circuit 62 in addition to the element 64 and a series capacitor 66, thus forming a low-resistance path for appropriate electrothermal preheating. Since the switch 60 is a bidirectional voltage-sensitive switch such as siduc switch, an electrode can be preheated appropriately even under a high-temperature restarting condition, thereby reducing sputtering of an emitted mixture on the electrode. Moreover, it is possible to improve ballast efficiency and effectiveness of a system.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates generally to all fluorescent lamps that are prone to improper instant starting under normal operating conditions, and more particularly to all fluorescent lamps that are electronically stabilized at high frequencies. The present invention relates to a compact fluorescent lamp (CFL) adapted to be properly started under the above-mentioned starting conditions, particularly under high temperature restart conditions.

[0002]

BACKGROUND OF THE INVENTION In the field of residential and consumer lighting, great efforts have been made over the last few years to replace compact incandescent bulbs with more compact fluorescent lamps for wider public use. . The acceptance of such fluorescent lamps in society results in energy savings and the generation of such energy, as fluorescent lamps save significant energy while maintaining the same light output level compared to when using incandescent bulbs. It can contribute to the great goal of conserving the natural resources used for. Compact fluorescent lamps have been introduced for this purpose, and compact fluorescent lamps are the fastest growing segment of the fluorescent lamp market today.

Lamps that use mercury with argon as a means of converting ultraviolet energy into visible light are classified as low pressure fluorescent discharge lamps. One type of such compact lamps on the market is called twin-tube lamps, whose wattage usually ranges from 5W to 50W. Double twin tube lamps, commonly referred to as quads, are also commercially available and operate within the same wattage range and also have the desired compactness characteristics. Furthermore, the present invention, regardless of magnitude or voltage,
It can also be applied to arbitrary fluorescent lamps that tend to have inappropriate instantaneous starting conditions, especially high temperature restart conditions.

Since many of the electronic ballasts developed for these compact lamps produce high starting voltages,
Many of the compact lamps, including quad and hex, are all susceptible to inadequate instantaneous starting conditions. Two of the prior art circuits that attempt to mitigate the starting problems associated with compact electronically stabilized fluorescent lamps.
One example can be found in US Pat. Nos. 4,647,817 and 4,647,820. Each patent describes the use of PTC elements as a means for preheating the electrodes of the lamp, but there is no description of circuit operation under hot re-ignition conditions. Another example of a ballast circuit for a compact fluorescent lamp is US Pat. No. 5,122,712.
No. In this patent, the PTC element is used in combination with a diode to disconnect the starting circuit after activation, thereby eliminating energy loss through the PTC. Yet another example of an electronic ballast for a compact fluorescent lamp with preheat function is US Pat.
No. 027,033. In this patent, a relay circuit is placed in the PTC circuit for disconnection of the preheat circuit. A rectifier and capacitor circuit is used to control the relay coil, which adds cost and complexity to the overall ballast configuration described in this patent.

Therefore, it would be highly desirable to provide an improved electronic ballast with a special circuit for proper starting under all conditions, including hot restart conditions, which is a present invention. Is one of the purposes.

[0006]

SUMMARY OF THE INVENTION The present invention provides a ballast circuit arrangement particularly suitable for application in compact fluorescent discharge lamps. A ballast circuit has been developed that adds a voltage-responsive bidirectional electronic switch in series with a positive temperature coefficient (PTC) device. INDUSTRIAL APPLICABILITY The ballast circuit of the present invention can be used with any fluorescent lamp that is prone to improper instant starting, and is particularly applicable to compact fluorescent lamps, including electronically stabilized quad or hex fluorescent lamps. can do. Since many electronic ballast circuits for compact fluorescent lamps produce high starting voltages, such lamps are prone to inadequate instantaneous starting conditions and thus can benefit from the ballast circuit of the present invention.

According to one aspect of the invention, a ballast circuit for a discharge lamp includes a PTC element to initially create a low resistance path for proper electrode heating. A bidirectional switching means is connected in series with the PTC element to thereby properly electrically connect the low resistance path each time the lamp power is switched on, improving hot restart conditions. . Furthermore, a capacitor is connected in series to properly set the value of the electrode preheating current.

Accordingly, one object of the present invention is to provide a ballast circuit that improves the hot restart characteristics of a discharge lamp so that hot restart conditions are as satisfied as normal or cold starting conditions. That is. It is also an inherent advantage of the present invention that such a ballast circuit improves stability efficiency and system effectiveness, as it eliminates the losses associated with dormant cathode current during normal operation. The ballast circuit of the present invention improves the restart condition and thus the life of the entire lamp.

Other objects and advantages of the invention will be apparent from the following description, drawings, and claims.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following description refers to the accompanying drawings. FIG. 1 shows a prior art electronic ballast circuit 10 used in an existing integrated stabilized compact fluorescent lamp (CFL) 12. The input voltage / current waveform is connected to the full wave bridge rectifier 14. Full-wave bridge rectifier 14 converts low frequency inputs on the order of 60 Hertz to rectified direct current. The input of this circuit may also include an electrical fuse 16 and a transient current protection device such as a metal oxide varistor 18. Various electrical filters composed of capacitors 20 and 22, resistors 24 and 26, and inductor 28 smooth the DC current. As a result, a more stable direct current can be applied to the high frequency inverter circuit 30. The high frequency inverter circuit 30 converts direct current into high frequency alternating current. Capacitor 2
2 and the resistors 24 and 26 are used in the electronic ballast circuit 10.
An RC time constant network for the starting inverter circuit of. A first switch, such as a SIDAC switch 27, provides an input to the starting inverter circuit 30.

Continuing to refer to FIG. next,
The high frequency alternating current passes through the stable impedance including the feedback transformer 32 and the resonant stable inductor 34. The feedback transformer 32 and the resonant stabilizing inductor 34 set the proper starting / running power value to be applied to the lamp 12. The circuit also includes a capacitor 36 and a parallel resonant capacitor 38. The electrode preheating circuit 40 includes a PTC element 42 and a series capacitor 44.

Referring now to FIG. 2, a block diagram of a typical electronic ballast circuit made in accordance with the present invention is shown. Input unit 46 with fuse and transient current protection element
However, AC voltage / current waveform is converted to AC / DC bridge rectifier 4
Connect to 8. The AC / DC bridge rectifier 48 produces a DC output. The inverter 50 converts direct current into high frequency alternating current. The high frequency alternating current passes through the high frequency stable impedance of the block 52. For the high frequency stable impedance of the block 52, set an appropriate electrode preheat value in the block 54,
Block 56 sets the appropriate operating value for the lamp. The electrode preheat step of block 54 includes bidirectional voltage responsive switch means, such as a SIDAC, which is described in more detail with reference to FIG.

FIG. 3 is a circuit diagram showing the block diagram of FIG. The electronic ballast circuit 58 of FIG. 3 includes any existing integrated, stabilized, compact fluorescent lamp (C
FL) 12 can be used to ensure proper starting under all starting conditions, especially under hot restart conditions.
As in FIG. 1, the input voltage / current waveform is electrically connected to the full wave bridge rectifier 14. Full wave bridge rectifier 14
Converts the low frequency input to rectified direct current. Since the electric filter smoothes the direct current, a more stable direct current can be applied to the high frequency inverter circuit 30. The high frequency inverter circuit 30 converts direct current into high frequency alternating current. This high frequency alternating current then passes through the stable impedance. The stable impedance sets the appropriate starting / running power value to be applied to the lamp 12.

Continuing to refer to FIG. Circuit 5
8 differs from the prior art circuit 10 of FIG. 1 in that a bidirectional electronic switch means 60 has been added to the electrode preheat circuit 62. At this time, the electrode preheating circuit 62 includes a switch 60,
It is composed of a PTC element 64 and a series capacitor 66. The PTC element 64 is electrically connected in series with the bidirectional switch 60 to initially form a low resistance path for proper electrode preheating. A series connected capacitor 66 sets the electrode preheat current appropriately for the lamp 12 electrodes. Electrodes are placed inside the glass of the lamp, one at each end, to supply the electrons and thus the current to operate the lamp 12. In the preferred embodiment of the present invention, switch 60 is a bidirectional voltage responsive switch, such as a SIDAC switch. Sidac (SIDA
C) The switch reduces sputtering of the emissive mixture on the electrode during hot restart by ensuring that the electrode is preheated properly even in hot restart conditions.

Continuing to refer to FIG. The bidirectional switch 60 closes when the input power to the ballast circuit is off. As soon as the power is turned on, the electrode preheating circuit 6
Current flows through 2 and the lamp 12 is subsequently started. Once the lamp is started, the voltage-responsive bidirectional switch 60 is opened electrically, so that the PTC6 of the electrode preheating circuit 62 is
Stop any quiescent current through 4. The removal of the quiescent current causes the PTC 64 to return to its low electrical value, so that the next time power is turned on, the electrode preheat circuit 62 will be fully operational, whether normal or hot.

Although the present invention has been described in detail with reference to preferred embodiments, it will be understood that variations and modifications can be made within the spirit and scope of the invention.

[Brief description of drawings]

FIG. 1 is a representative schematic circuit diagram of an electronic ballast circuit for a compact fluorescent lamp made in accordance with the prior art.

FIG. 2 is a block diagram of an electronic ballast circuit made in accordance with the present invention.

FIG. 3 is a schematic circuit diagram of the electronic ballast circuit of FIG. 2 made in accordance with the present invention.

[Explanation of Codes] 12 Compact Fluorescent Lamp 58 Electronic Stabilization Circuit 60 Bidirectional Switch 62 Electrode Preheating Circuit 64 PTC Element 66 Series Capacitor

Claims (4)

[Claims] 1. A ballast circuit for controlling the current for operating a low pressure discharge lamp, comprising an electronic circuit for converting a low frequency AC input into a high frequency AC output to a low pressure discharge lamp, and a discharge lamp. And a preheating circuit connected between both ends of the electrode member, the preheating circuit having a bidirectional switching means for giving an appropriate electrode preheating state to the electrode under any starting condition. Stabilizer circuit. 2. A positive temperature coefficient element in which the preheating circuit is connected in series with the bidirectional switching means to initially form a low resistance path for proper electrode preheating, and an electrode preheating current for the electrodes. 2. The ballast circuit of claim 1 including a series connected capacitor for properly setting. 3. The ballast circuit according to claim 2, wherein the bidirectional switching means improves stability efficiency and effectiveness at the same time by eliminating resting electrode loss during normal lamp operation. 4. The ballast circuit of claim 2 wherein said bidirectional switching means provides an appropriate electrode preheat condition for said electrode during a hot restart condition.