IMAGE FORMING APPARATUS

• US 20110085808A1
• Filed: 09/16/2010
• Published: 04/14/2011
• Est. Priority Date: 10/08/2009
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Hirata, Yuichiro
• Granted Patent: US 8,478,140 B2
• Time in Patent Office: Days
• US Class Current: 399/27
• CPC Class Codes: G03G 15/0808 characterised by the developer supplying means, e.g. structure of developer supply roller
• CPC Class Codes: G03G 15/0856 Detection or control means for the developer level
• CPC Class Codes: G03G 15/086 the level being measured by electro-magnetic means
• CPC Class Codes: G03G 15/0877 Arrangements for metering and dispensing developer from a developer cartridge into the development unit
• CPC Class Codes: G03G 15/553 Monitoring or warning means for exhaustion or lifetime end of consumables, e.g. indication of insufficient copy sheet quantity for a job
• CPC Class Codes: G03G 15/556 for toner consumption, e.g. pixel counting, toner coverage detection or toner density measurement

Abstract

An image forming apparatus includes an image bearing member and a developing device for developing an electrostatic latent image. The developing device includes a developer container, a rotatable developer carrying member, including a first electrode member; and a developer supplying member, including a second electrode member. The apparatus further includes a measuring device capable of measuring a remaining developer amount; and a replenishing device for performing a replenishing operation by rotating the developer supplying member while applying a DC bias between the first and second electrode members so that a value obtained by subtracting an electric potential of the second electrode member from an electric potential of the first electrode member has a polarity identical to a normal charge polarity of the developer. When the remaining developer amount measured is not more than a threshold, the replenishing operation is performed and the remaining developer amount is measured again.

Claims

1. An image forming apparatus comprising:

an image bearing member on which an electrostatic latent image is to be formed;

a developing device for developing the electrostatic latent image by supplying a developer to said image bearing member, said developing device including;

a developer container for containing the developer;

a rotatable developer carrying member, including a first electrode member, for carrying and supplying the developer to said image bearing member; and

a developer supplying member, which is provided in contact with said developer carrying member and includes a surface foam layer and a second electrode member for rotatably supporting said developer supplying member, for supplying the developer to said developer carrying member;

a measuring device capable of measuring a remaining developer amount in said developer container by detecting electrostatic capacity between the first electrode member and the second electrode member; and

a replenishing device for performing a replenishing operation for replenishing said developer supplying member with the developer by rotating said developer supplying member while applying a DC bias between the first electrode member and the second electrode member so that a value obtained by subtracting an electric potential of the second electrode member from an electric potential of the first electrode member has an identical polarity to a normal charge polarity of the developer,

wherein when the remaining developer amount measured by said measuring device is not more than a threshold, the replenishing operation is performed by said replenishing device and thereafter the remaining developer amount is measured again by said measuring device.

2. An apparatus according to claim 1, wherein the replenishing operation is performed by said replenishing device also when a value obtained by subtracting the remaining developer amount measured by said measuring device in current measurement from the remaining developer amount measured by said measuring device in preceding measurement exceeds a predetermined value, and thereafter the remaining developer amount is measured again by said measuring device.

3. An image forming apparatus comprising:

an image bearing member on which an electrostatic latent image is to be formed;

a developing device for developing the electrostatic latent image by supplying a developer to said image bearing member, said developing device including;

a developer container for containing the developer;

a rotatable developer carrying member, including a first electrode member, for carrying and supplying the developer to said image bearing member; and

a developer supplying member, which is provided in contact with said developer carrying member and includes a surface foam layer and a second electrode member for rotatably supporting said developer supplying member, for supplying the developer to said developer carrying member;

a first measuring device for measuring a remaining developer amount in said developer container;

a second measuring device capable of measuring the remaining developer amount by detecting electrostatic capacity between the first electrode member and the second electrode member; and

a replenishing device for performing a replenishing operation for replenishing said developer supplying member with the developer by rotating said developer supplying member while applying a DC bias between the first electrode member and the second electrode member so that a value obtained by subtracting an electric potential of the second electrode member from an electric potential of the first electrode member has an identical polarity to a normal charge polarity of the developer,

wherein when the remaining developer amount measured by said first measuring device is not more than a threshold, the replenishing operation is performed by said replenishing device and thereafter the remaining developer amount is measured by said second measuring device.