Transfer medium separating device
First Claim
1. A separating device for separating a transfer medium from a first carrier adapted to carry a toner image held electrostatically, said transfer medium having been previously brought into contact with said first carrier to transfer a toner image from said first carrier onto the front surface of said transfer medium by applying transfer charges of a polarity opposite to the polarity of the toner forming said toner image to the rear surface of the transfer medium, said separating device comprisingmeans including a second carrier formed of an electrically conductive material and having a portion located close to said first carrier for attracting the leading edge of said transfer medium by electrostatic attraction between said transfer charges on the rear surface of the transfer medium and charges on said second carrier;
- potential application means for applying a potential in the range between a predetermined first level and a predetermined second level to said second carrier, said first level being capable of electrostatically attracting the leading edge of said transfer medium toward said second carrier from said first carrier and said second levelbeing capable of securely retaining the transferred toner image to the front surface of said transfer medium when said transfer medium is conveyed by said second carrier;
detecting means for detecting that said transfer medium has reached a reference position for supplying a detection signal; and
timing control means for controlling the timing for changing the potential applied to said second carrier by said potential application means from said first level toward said second level in response to said detection signal such that said second carrier is applied with a potential of said first level until the leading edge of said transfer medium has been separated from said first carrier and electrostatically attracted and securely held to said second carrier.
1 Assignment
0 Petitions
Accused Products
Abstract
In a copy paper separating device for use in a transfer type electrophotographic copying machine which includes a conductive carrier member, preferably in the form a conductive endless belt extended between a pair of pulleys. The conductive carrier member is disposed in the periphery of the photosensitive member to which a copy paper is brought into contact for the transfer of a toner image formed on the photosensitive member. The potential of the conductive carrier member is maintained nearly at zero level during the first step of the separating operation; whereas, the potential of the carrier member is increased to a predetermined value of the polarity opposite to that of the toner image during the second step.
15 Citations
18 Claims
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1. A separating device for separating a transfer medium from a first carrier adapted to carry a toner image held electrostatically, said transfer medium having been previously brought into contact with said first carrier to transfer a toner image from said first carrier onto the front surface of said transfer medium by applying transfer charges of a polarity opposite to the polarity of the toner forming said toner image to the rear surface of the transfer medium, said separating device comprising
means including a second carrier formed of an electrically conductive material and having a portion located close to said first carrier for attracting the leading edge of said transfer medium by electrostatic attraction between said transfer charges on the rear surface of the transfer medium and charges on said second carrier; -
potential application means for applying a potential in the range between a predetermined first level and a predetermined second level to said second carrier, said first level being capable of electrostatically attracting the leading edge of said transfer medium toward said second carrier from said first carrier and said second level being capable of securely retaining the transferred toner image to the front surface of said transfer medium when said transfer medium is conveyed by said second carrier; detecting means for detecting that said transfer medium has reached a reference position for supplying a detection signal; and timing control means for controlling the timing for changing the potential applied to said second carrier by said potential application means from said first level toward said second level in response to said detection signal such that said second carrier is applied with a potential of said first level until the leading edge of said transfer medium has been separated from said first carrier and electrostatically attracted and securely held to said second carrier. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A transfer type electrophotographic copying machine comprising:
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a photosensitive member supported to move along a predetermined path; image forming means for forming a toner image on the surface of said photosensitive member; feeding means for feeding a transfer medium along a predetermined traveling path whereby the front surface of said transfer medium is brought into contact with the surface of said photosensitive member, transfer charging means for transferring said toner image onto the front surface of said transfer medium by applying charges of the polarity opposite to that of said toner image to the rear surface of said transfer medium; and separating means for separating said transfer medium from the surface of said photosensitive member, wherein said separating means includes; means including an electrically conductive carrier member having a portion located close to said photosensitive member for separating and attracting the leading edge of said transfer medium to said portion by electrostatic induction; potential application means for applying a potential in the range from a predetermined first level to a predetermined second level to said carrier member, said first level being capable of electrostatically attracting the leading edge of said transfer medium to said carrier member from said photosensitive member and said second level being capable of securely holding the transferred toner image in the front surface of said transfer medium when said transfer medium is placed on said carrier member; detecting means for detecting the existence of said transfer medium at a reference position in its traveling path thereby supplying a detection signal; and timing control means for controlling the timing for changing the potential applied to said carrier member by said potential application means in response to said detection signal from said first level, which is normally applied to said carrier member, toward said second level, which is temporarily applied to said carrier member until completion of the separating operation, such that said timing control means keeps said carrier member substantially at said first level until the leading edge of said transfer medium has been separated and attracted to said carrier member from said photosensitive member due to electrostatic induction and is securely held to said carrier member. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification