Developing apparatus

• US 20050214001A1
• Filed: 03/24/2005
• Published: 09/29/2005
• Est. Priority Date: 03/26/2004
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Sakamaki, Tomoyuki
• Granted Patent: US 7,231,154 B2
• Time in Patent Office: Days
• US Class Current: 399/27
• CPC Class Codes: G03G 15/0822 Arrangements for preparing, mixing, supplying or dispensing developer
• CPC Class Codes: G03G 2215/0822 with wall or blade between agitators
• CPC Class Codes: G03G 2215/0838 Circulation of developer in a closed loop within the sump of the developing device

Abstract

A developing device for developing an electrostatic image formed on an image bearing drum, includes a developing container for accommodating a developer including toner and carrier; developer stirring means provided in the developing container; a developer carrying sleeve for carrying the developer to an opposing portion where the sleeve is opposed to the drum; supplying means for supplying a developer including toner and carrier into the developing container; discharging means for discharging the developer from the developing container; supply control means for controlling a supplying operation of the supplying means to control a toner content in the developer in the developing container, wherein an amount of the developer A (g) in the developing container when a difference between an amount of the carrier supplied by the supplying means per unit time and an amount of discharge of the carrier by the discharging means per unit time becomes not more than 5 (g/min) during development of an electrostatic image having an image density of 100%, and an amount of the developer in the developing container B (g) when an amount of discharge of the carrier per unit time becomes not more than 0.5 (g/min) without the supply of the carrier from the supplying means, satisfy,
0.01≦(A−B)/A≦0.10.

Claims

1. A developing apparatus for developing an electrostatic image formed on an image bearing member, said developing apparatus comprising:

a developing container for accommodating a developer including toner and carrier;

developer stirring means provided in said developing container;

a developer carrying member for carrying the developer to an opposing portion where said developer carrying member is opposed to said image bearing member;

supplying means for supplying a developer including toner and carrier into said developing container;

discharging means for discharging the developer from said developing container;

supply control means for controlling a supplying operation of said supplying means to control a toner content in the developer in said developing container,

wherein an amount of the developer A (g) in said developing container when a difference between an amount of the carrier supplied by said supplying means per unit time and an amount of discharge of the carrier by said discharging means per unit time becomes not more than 5 (g/min) during development of an electrostatic image having an image density of 100%, and

an amount of the developer in said developing container B (g) when an amount of discharge of the carrier per unit time becomes not more than 0.5 (g/min) without the supply of the carrier from said supplying means, satisfy,

0.01≦

(A−

B)/A≦

0.10.

2. An apparatus according to claim 1, wherein the amount B is determined with the image density of 0%.

3. An apparatus according to claim 1, wherein the developer amount A (g) is 100-2000 (g).

4. An apparatus according to claim 1, wherein a weight percentage of the carrier in the supply developer to be supplied by said supply means is 3-40 (%).

5. An apparatus according to claim 1, wherein a maximum carrier supply amount per unit time by said supplying means is 1-25 (g/min).

6. An apparatus according to claim 1, wherein an amount of the toner on said image bearing member per unit area when an electrostatic image having an image density of 100% is developed, is 0.3-0.8 (mg/cm²)

7. An apparatus according to claim 1, wherein an angle of repose of said developer is 20-70 (°

).

8. An apparatus according to claim 1, wherein said discharging means is provided with an opening for discharging the developer from the developing container, and a position of the opening is adjustable.