Electric lamp and discharge devices: systems – Current and/or voltage regulation – Automatic regulation
Patent
1994-09-22
1996-02-13
Pascal, Robert J.
Electric lamp and discharge devices: systems
Current and/or voltage regulation
Automatic regulation
315307, 315208, 315224, 315DIG4, 315DIG7, G05F 100
Patent
active
054913888
DESCRIPTION:
BRIEF SUMMARY
SPECIFICATION
1. Industrial Field
The present invention relates to a power regulator for regulating a discharge lamp and executing a dimmer control, and also to a variable color illuminating apparatus using the regulator.
2. Prior Art
Alternating current is required to energize a discharge lamp, and a conventional discharge lamp regulator with a dimmer circuit for regulating a discharge lamp and executing a dimmer control is disclosed, for example, Japanese Patent Laid-Open Gazette No. H-2-197093.
The discharge lamp regulator converts an alternating current obtained from a commercial ac power source to a direct current with a rectifier and transmits the direct current to a full-bridge inverter circuit while inputting an ac control signal to a gate terminal of the inverter circuit. The inverter circuit then converts the direct current to a square-wave alternating current, which is supplied to energize the discharge lamp.
The discharge lamp regulator further includes a dimmer control circuit for outputting the ac control signal to the gate terminal of the inverter circuit. The control circuit superposes off-times on the on/off operation of the inverter circuit according to luminance reduction of the lamp, thereby substantially executing the dimmer control through the frequency regulation.
Since the dimmer controller executes the frequency regulation, luminance reduction often causes a long off-time in which no power is supplied to the discharge lamp, and further causes undesirable turn-out of the discharge lamp.
In other words, the conventional dimmer controller can not stably reduce the luminance of the discharge lamp and has a very narrow dimmer-operation range.
Moreover, since the dimmer control circuit has a circuit structure to generate the ac control signal for executing the on/off operation and superposing the quiescent time during the on-off operation, the control circuit has a rather complicated and cost-consuming structure.
There is a known technique of controlling the luminance of fluorescent lamps or other similar discharge lamps at a relatively high frequency with an inverter circuit. This technique is, however, not applicable to the control of high illuminance discharge lamps such as metal halide lamps at a constant high frequency because it causes the resonance of the lamps which may result in unintentional turn-out of the lamps.
The metal halide lamps can be regulated stably only at frequencies of a restricted range, and the dimmer control through the frequency regulation is accordingly difficult for the metal halide lamps.
Incidentally, the dimmer control is also desired in variable color illumination apparatus which can vary the chromaticity.
Typical examples of known devices for continuously varying the chromaticity of light emitted from discharge lamps are those disclosed in Japanese Patent Publication Gazette No. S-53-42386 and Japanese Patent Laid-Open Gazette No. S-63-98295. These devices use gases or vapors which are sealed as a luminous body in a discharge lamp and varied the luminous color depending upon the electronic energy in the discharge lamp, and change the color by varying the waveform of a power pulse supplied to the discharge lamp. For example, a relatively large ratio of the power supply time to the quiescent time gives blue light while a relatively small ratio gives red light.
In such devices, however, red light is obtained by extending the quiescent time of a power pulse, and the power supply to the discharge lamp is accordingly reduced. Therefore, in some case, it is difficult to obtain a stable luminance.
A first object of the present invention is thus to provide a power regulator which prevents a discharge lamp from undesirably turning out even during a dimmer control in which the power supply to the discharge lamp is fairly reduced, and which offers a wide range of stable dimmer control.
A second object of the invention is to provide a variable color illumination apparatus which has a sufficient and stable luminance, and which can vary the chromaticity of the light
REFERENCES:
patent: 4277728 (1981-07-01), Stevens
patent: 4356433 (1982-10-01), Linden
patent: 4471269 (1984-09-01), Ganser et al.
patent: 4791338 (1988-12-01), Dean et al.
patent: 4949016 (1990-08-01), De Bijl et al.
patent: 5334915 (1994-08-01), Ohsaki et al.
PCT-Notification of Transmittal of Copies of Translation of the International Preliminary Examination Report, Dated Aug. 31, 1994, PCT/JP93/00353.
Robert Hall, et al., 122nd Annual SMPTE Technical Conference, Nov. 9-14, 1980, New York, "High-Power Single-Ended Discharge Lamps for Film Lighting"; Printed Aug. 1981, pp. 678-685.
Hidetoshi Tsuji
Nobuyuki Yamada
Takahiro Douke
Pascal Robert J.
Philogene Haissa
Toto Ltd.
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