Electric lamp and discharge devices: systems – Surge generator or inductance in the supply circuit – Circuit interrupter in the inductance circuit
Patent
1979-11-18
1983-03-29
LaRoche, Eugene R.
Electric lamp and discharge devices: systems
Surge generator or inductance in the supply circuit
Circuit interrupter in the inductance circuit
315239, 315276, 315DIG5, H05B 4116
Patent
active
043785158
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to discharge lamp lighting devices for copying machines. More particularly, it relates to a discharge lamp lighting device for copying machine wherein, in an electrostatic copying machine of a type in which, for example, a reflected light from objects to be copied as irradiated in turn with a light source moving with a slit of a width of about 5 mm. to diaphragm its flux of light is recorded on a rotary electrostatic drum, a light output of the discharge lamp which is the light source is made optimum to apply to such electrostatic copying machine.
In this discharge lamp lighting device for copying machines, the lamp current to be flowed to the discharge lamp is set to be of substantially rectangular waves so that the light output of the light source will be substantially constant at any timing of each half cycle of an alternating current source voltage and, particularly in the case of using it in the electrostatic copying machine in which the light irradiation on the object to be copied is momentary, a favorable copying result will be able to be always expected.
BACKGROUND ART
Conventionally, for generally known discharge lamp lighting device for electrostatic copying machines, there has been one, as shown, for example, in FIG. 1, which is started by an application of a secondary voltage (for example, of 150 volts) of a leakage autotransformer T.sub.1 to a filament preheating type fluorescent lamp L.sub.1 which is a light source through a phase advancing capacitor C.sub.1 by closing a switch S.sub.1. However, according to such conventonal type, there is a possibility that, as its discharge circuit forms a phase advancing circuit, the light output wave form will be disturbed and the period in which the light output of the fluorescent lamp exceeds a required level L will be so short that, in the period in which the light output is not sufficient, the copying will not be made normal (see FIG. 2A). More specifically, in the period in which the light is not sufficiently provided, the irradiated amount of light on the object to be copied will be so small that, even if the object is white, it will be discriminated to be black and no fidelity copying will be made any more.
Such problem is not limited only to the above described typical conventional lighting device but also exists in the case of obtaining a light output wave form substantially of a sine wave form by lighting the discharge lamp with a use of, for example, a choke coil type stabilizer. That is, in this case, too, the period in which the light output of the fluorescent lamp exceeds the required level L will be so short that there will be the same problem as described above (see FIG. 2B) and, in these cases, an elevation of the absolute value of light amount of the discharge lamp to some extent does not result in a fundamental solution of the problem.
Referring again to the above described problem in the discharge lamp lighting circuit of FIG. 1 shown as a typical conventional example, a lamp current of about 0.8 A. flows through the fluorescent lamp L.sub.1 after it is lighted, the lamp voltage of the fluorescent lamp in this case is about 40 volts, so that the ratio of the secondary voltage V.sub.2 of the transformer required for starting this lamp to the lamp voltage V.sub.La will be V.sub.2 /V.sub.La .apprxeq.3.8, wherein.apprxeq.means "substantially equals". Thus, the value of V.sub.2 /V.sub.La in the general discharge lamp lighting devices for copying machines shows a value generally considerably larger than the value of about 2.0 of general illumination stabilizers for starting general illumination lamps which are improved for easy starting. Here, the stabilizers generally high in this value of V.sub.2 /V.sub.La are preferable since fluctuations in the lamp current with respect to fluctuations in the source voltage are low but, on the other hand, in the case of forming a phase advancing circuit, the wave form of the lamp current will deteriorate so that the light output wave form of the lamp will also d
REFERENCES:
patent: 3069597 (1962-12-01), Feinberg
patent: 3371245 (1968-02-01), Hume
patent: 3903452 (1975-09-01), Nakai et al.
Ashida Yoshiaki
Hashimoto Tsuguhito
Nakai Kenichi
Onoe Kenichi
LaRoche Eugene R.
Matsushita Electric & Works Ltd.
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