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US 2006/0222390 A1Published application
Electrophotographic image forming device and developing method thereof
AssigneeSamsung Electronics Co., Ltd.
InventorsTsutomu Sasaki, Kyu-cheol Shin, Myung-kook Ahn, Masahiko Itaya, Tsutomu Teraoka, Naonori Kurogawa
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Abstract
Provided is an image forming device performing hybrid development that uses magnetic carriers and nonmagnetic carriers. An electrical potential of a non-image portion on an image holder and an electrical potential of a direct current component of a developing bias voltage applied to a developing roller are determined so that a difference between the electrical potentials are less than or equal to a value at which a developing rate of the non-image portion is saturated.
Claims14
An electrophotographic image forming device comprising:
- an image holder on which an electrostatic latent image including an image portion and a non-image portion is formed;
- a magnetic roller for forming by a magnetic force a magnetic brush comprising nonmagnetic toner and a magnetic carrier;
- a developing roller disposed between the image holder and the magnetic roller for receiving toner from the magnetic roller and for forming a toner layer on an outer circumference of the developing roller;
- and
- a bias applying unit for applying to the magnetic roller a supply bias voltage effective in supplying toner to the developing roller and for applying to the developing roller a developing bias voltage effective in developing the toner into the electrostatic latent image,
- wherein a difference between an electrical potential of the non-image portion and an electrical potential of a direct current (DC) component of the developing bias voltage is less than or equal to a value at which a developing rate of the non-image portion is saturated.
3 more elements
An electrophotographic image forming device comprising:
- an image holder on which an electrostatic latent image including an image portion and a non-image portion is formed;
- a magnetic roller for forming by a magnetic force a magnetic brush comprising nonmagnetic toner and a magnetic carrier;
- a developing roller and a collecting roller disposed upstream and downstream, respectively, as viewed in a direction of rotation of the image holder, between the image holder and the magnetic roller;
- and
- a bias applying unit for applying to the magnetic roller a supply bias voltage effective in supplying toner to the developing roller and for applying to the developing roller a developing bias voltage effective in developing the toner into the electrostatic latent image, the developing bias voltage being a combination of a direct current (DC) and an alternating current (AC), and a collecting bias voltage effective in collecting toner attached to the non-image portion on the collecting roller,
- wherein a difference between an electrical potential of the non-image portion and an electrical potential of a DC component of the developing bias voltage is less than or equal to a value at which a developing rate of the non-image portion is saturated, the developing rate being calculated using the following equation:
- developing rate={(ODBD−ODAD)/ODBD}×100%,
- wherein ODBD is the optical density of a toner layer on developing roller before development and ODAD is optical density of a toner layer on developing roller after development.
5 more elements
A hybrid developing method, comprises:
- supplying toner from a magnetic brush of a magnetic roller to a developing roller;
- and
- applying a developing bias voltage to the developing roller to develop the toner into an electrostatic latent image on an image holder, wherein the developing bias voltage is set so that a difference between a potential of a direct current (DC) component of the developing bias voltage and an electrical potential of a non-image portion of the electrostatic latent image is no more than an electrical potential difference at which the developing rate of the non-image portion is saturated, and the set developing bias voltage reduces the adhesion of toner remaining on the developing roller after development to the developing roller.
Dependencies are inferred from the claim text.