Discharge lamp operating system

• US 4,238,708 A
• Filed: 01/30/1978
• Issued: 12/09/1980
• Est. Priority Date: 01/09/1975
• Status: Expired due to Term

• Current Assignee: New Nippon Electric Company Limited
• Original Assignee: New Nippon Electric Company Limited
• Inventors: Kaneda, Isao
• Primary Examiner(s): LaRoche, Eugene R.
• Application Number:
  US05/873,241
• Time in Patent Office: 1,044 Days
• Field of Search: 315/101, 315/105, 315/274, 315/276, 315/283, 315/284, 315/289, 315/290, 315/DIG. 2, 315/DIG. 5, 315/244, 315/DIG. 7
• US Class Current: 315/289
• CPC Class Codes: H05B 41/042 using semiconductor devices
• CPC Class Codes: H05B 41/044 for lamp provided with pre-heating electrodes
• CPC Class Codes: Y10S 315/02 High frequency starting operation for fluorescent lamp

Abstract

A discharge lamp is ignited in every half cycle in its operating system including a discharge lamp operating circuit provided with a low frequency alternating current power source, a single winding type current limiter. The discharge lamp is connected to the power source through the current limiter and a series circuit including a high voltage output generator is connected in parallel to the discharge lamp. The high voltage output generator operates during the lamp operation for reigniting the discharge lamp. The voltage of the low frequency alternating current power source is set to less than the required reignition voltage of the discharge lamp during its operation, whereby the lamp current stabilizer size is minimized. Further, a filament preheating circuit is arranged to use current derived from the high voltage generator. The filament preheating circuit is combined with this operating circuit and so is a time delay for assuring a stable operation.

Claims

1. A discharge lamp operating system for sustaining the lit condition of discharge lamp means, comprising an electrical a.c. power source having a given low frequency, lamp current limiting means connecting said a.c. power source to said discharge lamp means for establishing lighting conditions for said discharge lamp means, and reignition means connected across said discharge lamp means, said reignition means comprising oscillator circuit means (R1) and an intermittently oscillating capacitor (C1) supplying an intermittent output, having a frequency higher than said given low frequency, directly to the discharge lamp means immediately after every pause period of every half cycle whereby the reignition means sustain said lit condition by the intermittent output current of said oscillator circuit means which sustains a constant reignition voltage even if the a.c. power source should supply a varying voltage, whereby the oscillator circuit means constitute a self-oscillating independent high frequency output power source, said current limiting means comprising a single winding current limiter, wherein the voltage of said a.c. power source is established below the required reignition voltage of said discharge lamp means during its operation, whereby said discharge lamp means is reignited by supplying an initial discharge lamp current value as an input current to said reignition means in every half cycle of said a.c. power source, so that the lit condition is substantially independent of the effective voltage of said a.c. power source.

2. The operating system of claim 1, wherein said single winding current limiter is a choke coil having end terminals only.

3. The operating system of claim 1, wherein said single winding current limiter is a leakage inductance of a transformer.

4. The operating system of claim 1, wherein said discharge lamp means comprise a plurality of discharge lamps serially connected and sequentially ignited in operation.

5. The operating system of claim 1, wherein said reignition means comprises an oscillator and an intermittently oscillating capacitor, said oscillator including an oscillation capacitor and a series circuit of a switching means and a boosting inductor in parallel connection, and wherein said reignition means is energized by said power source to generate an intermittently high frequency high voltage output, at a point of time just prior to ignition of said discharge lamp means.

6. The operating system of claim 5, wherein said switching means comprises one or more bi-directional two terminal thyristors having an effective break-over voltage higher than the lamp voltage of said discharge lamp means and lower than the voltage of said power source.

7. The operating system of claim 5, wherein time delay means are connected between said discharge lamp means and said current limiting means whereby the ignition phase of said reignition means is controlled at every half cycle of said power source prior to the ignition of said discharge lamp means.

8. The operating system of claim 7, wherein said time delay means include an inductor and means for changing the inductance of said inductor in response to the activation of said reignition means.

9. The operating system of claim 8, wherein said means for changing the inductance is a bias coil which is energized by the current flowing through said reignition means and at the same time acts as a bias winding by a magnetic coupling with said inductor.

10. The operating system of claim 5, wherein said discharge lamp means is a hot-cathode type discharge lamp having a filament, and further comprising a preheating circuit for said filament, said preheating circuit including said filament located within said reignition means so as to flow current through said filament.

11. The operating system of claim 10, wherein said preheating circuit includes a high frequency insulating transformer located within the closed circuit of said reignition means, said insulating transformer supplying a part of the energy output from said reignition means to said filament of said discharge lamp.

12. The operating system of claim 11, wherein a plurality of discharge lamps are employed in series connection, and wherein at least a part of the oscillation energy output of said reignition means is supplied to said filaments of said series connected discharge lamps by said high frequency insulating transformer.

13. The operating system of claim 10, wherein said reignition means comprises two oscillators in series connection, each of said filaments of said discharge lamp means being located within each of said oscillators so as to promote the preheating of said filaments.

14. The operating system of claim 10, wherein one of said oscillators includes sequentially operating means for the activation of said oscillators.