Patent ID: 6034790
Filing Date: 2000-03-07
Classification: G03G,H05B

Abstract:
A soft-starting system for a lamp in an image forming device, said soft-starting system comprising:input means for connecting said system to a source of alternating voltage defining a continuous series of sinusoidal waveforms, each said sinusoidal waveform comprising a 180 degree positive portion and a 180 degree negative portion; andcontrol means connected between said input means and said lamp for selecting, and for applying to said lamp during a predetermined initial lamp energizing period, a part of each said positive portion and a part of each said negative portion of each of said sinusoidal waveforms in said series;wherein:(i) said control means is adapted to divide each said positive portion and each said negative portion of each said waveform into an initial firing angle followed by a conducting angle,(ii) the part of each portion of each said sinusoidal waveform which is applied to said lamp is defined by said conducting angle,(iii) said conducting angle is the same for both said positive portion and said negative portion of each said waveform,(iv) said firing angle is gradually decreased and said conducting angle is gradually increased as said control means operates on each successive waveform of said series;(v) said system comprises a trigger timing table, a zero-cross counter for continuously counting the number of times said alternating voltage has a value of zero, and a timer;(vi) said trigger timing table includes predetermined firing angle and conducting angle value pairs associated with predetermined zero cross count value and timer value pairs;(vii) the operation of said zero cross counter and said timer are initiated at the beginning of power application to said system; and,(viii) said control means senses said zero cross value and timer value pairs, and gradually increases said conducting angle by gradually decreasing said firing angle in increments corresponding to said predetermined values thereof contained in said trigger timing table as successive ones of said predetermined zero count value and timer value pairs are sensed.