High duty cycle AC corona charger
First Claim
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1. A corona charger for charging a photoconductor, said charger comprising:
- at least one corona wire;
an AC voltage source connected to said corona wire, said AC voltage source having a duty cycle greater than 50% such that a potential on the corona wire is greater than a threshold voltage for corona emission for both positive polarity and negative polarity of the corona wire.
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Abstract
This invention pertains to an AC charger (10) in which an AC voltage waveform applied to a corona wires (12) has a duty cycle of between 50% and 90%. This increases the efficiency of the charger without increasing the signal-to-noise ratio. In one embodiment, the AC voltage waveform is asymmetric.
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Citations
29 Claims
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1. A corona charger for charging a photoconductor, said charger comprising:
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at least one corona wire; an AC voltage source connected to said corona wire, said AC voltage source having a duty cycle greater than 50% such that a potential on the corona wire is greater than a threshold voltage for corona emission for both positive polarity and negative polarity of the corona wire. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An AC corona charger, for charging a photoconductor comprising:
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at least one corona wire; a voltage controlled grid between said corona wire and a the photoconductor; means for applying an asymmetric AC voltage waveform to the corona wire, wherein said waveform has a time duration in a first polarity portion of said waveform, greater than a time duration in a second polarity portion of said waveform such that a potential on the corona wire is greater than a threshold voltage for corona emission for both positive polarity and negative polarity of the corona wire. - View Dependent Claims (14, 15, 16, 17)
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18. A corona charger for charging a photoconductor, said charger comprising:
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at least one corona wire; a voltage controlled grid between said corona wire and said photoconductor; a voltage source connected to said wire, whereby a corona charge is produced; and a function generator for applying an asymmetrical AC voltage waveform to said wire, wherein said waveform has a duty cycle greater than 50% such that a potential on the corona wire is greater than a threshold voltage for corona emission for both a positive polarity and a negative polarity of the AC voltage waveform. - View Dependent Claims (19, 20)
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21. In a corona charger for an electrophotographic copying system a method of charging a photoconductor comprising the steps of:
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applying an AC voltage signal having a duty cycle greater than 50% and to a corona wire wherein a potential on the corona wire is greater than a threshold voltage for corona emission for both a positive polarity and a negative polarity of the AC voltage signal; and applying a voltage to a grid, located between the corona wire and the phtoconductive. - View Dependent Claims (22, 23, 24)
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25. A corona charger for charging a photoconductor, said charger comprising:
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at least one corona wire; a shell partially surrounding said wire, said shell being open in the direction of the photoconductor; an AC voltage source connected to said corona wire for generating an AC waveform, said source having a duty cycle greater than 50%, such that a potential on the corona wire is greater than a threshold voltage for corona emission for both a positive polarity and a negative polarity of the AC waveform, and a time integrated AC component of the AC waveform on the corona wire has an absolute value greater than zero for at least one complete cycle of the AC waveform.
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26. An AC corona charger, the improvement therein comprising:
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at least one corona wire; a voltage source for applying an asymmetric AC voltage waveform to the corona wire, wherein said waveform has duration in a first polarity portion of said waveform, greater than a time duration in a second polarity portion of said waveform, wherein a potential on the corona wire is greater than a threshold voltage for corona emission for both a positive polarity and a negative polarity of the corona wire and a time integrated AC component of the voltage on the corona wire has an absolute value greater than zero for at least one complete cycle of the waveform.
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27. A corona charger for charging a photoconductor, said charger comprising:
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at least one corona wire; a voltage source to said wire, whereby a corona charge is produced; and means for applying an asymmetrical AC voltage waveform to said wire, wherein said waveform has a duty cycle greater than 50%, wherein a potential on the corona wire is greater than a threshold voltage for corona emission for both a positive polarity and a negative polarity of the AC voltage waveform, and a time integrated AC component of the voltage on the corona wire has an absolute value greater than zero for at least one complete cycle of the waveform.
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28. In a corona charger for an electrophotographic copying system a method of charging a phtotconductor comprising the steps of:
applying an AC voltage signal to a corona wire, wherein said AC voltage signal has a duty cycle greater than 50%, and a potential on the corona wire, is greater than a threshold voltage for corona emission for both a positive polarity and a negative polarity of the corona wire and a time integrated AC component of the voltage on the corona wire has an absolute value greater than zero for at least one complete cycle.
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29. In a corona charger for an electrophotographic copying system a method of charging a photoconductor comprising the steps of:
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applying an AC voltage signal to a corona wire; adjusting a potential of a grid located between the corona wire and the photoconductor such that a surface potential of the photoconductor, when said photoconductor fully charged, is equal to a first preselected voltage; setting said AC voltage signal to a preselected duty cycle which is greater than 50%; and setting a potential on the corona wire to a second preselected voltage which greater than a threshold voltage for corona emission for both a positive polarity and a negative polarity of the corona wire.
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Specification