IMAGE FORMING APPARATUS HAVING A DEVELOPER DETECTING UNIT

• US 20180004124A1
• Filed: 06/29/2017
• Published: 01/04/2018
• Est. Priority Date: 07/04/2016
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Shibukawa, Kenta, Kato, Masahito, Toda, Atsushi, Watanabe, Taku
• Granted Patent: US 10,444,671 B2
• Time in Patent Office: Days
• CPC Class Codes: G03G 15/086 the level being measured by electro-magnetic means
• CPC Class Codes: G03G 15/0865 Arrangements for supplying new developer
• CPC Class Codes: G03G 15/0889 for agitation or stirring
• CPC Class Codes: G03G 2215/0805 Cleaning blade adjacent to the donor member

Abstract

An image forming apparatus includes an agitating member, a first electrode, a second electrode disposed with a gap from the first electrode such that the gap has a smallest portion located below a rotation center of the agitating member and a remote portion wider than the smallest portion and located above the smallest portion, and a frame body having a first wall surface having the first electrode disposed thereon and a second wall surface having the second electrode disposed thereon, and a developer detecting unit configured to detect an amount of developer from an output value output in accordance with a capacitance formed between the first electrode and the second electrode. The image forming apparatus performs correction and detects the amount of developer.

Claims

1. An image forming apparatus comprising:

a developer container unit including

an agitating member configured to rotate and agitate developer,

a first electrode,

a second electrode disposed to face the first electrode with a gap therebetween such that the gap has a smallest portion located below a rotation center of the agitating member and a remote portion wider than the smallest portion and located above the smallest portion, and

a frame body configured to contain the agitating member and the developer and have a first wall surface having the first electrode disposed thereon and a second wall surface having the second electrode disposed thereon; and

a developer detecting unit configured to detect an amount of the developer by using an output value output in accordance with a capacitance formed between the first electrode and the second electrode, the developer detecting unit capable of detecting a first amount of developer and a second amount of developer that is smaller than the first amount of developer,

wherein when the output value corresponding to the first amount of developer is defined as a first reference value and a value having a first difference from the first reference value is defined as a second reference value indicating a magnitude of the output value corresponding to the second amount of developer, the first difference varies in accordance with a magnitude of the first reference value.

2. The image forming apparatus according to claim 1, wherein the developer detecting unit is capable of detecting a third amount of developer that is smaller than the first amount of developer and larger than the second amount of developer, and

wherein when a difference between the output value corresponding to the third amount of developer and the first reference value is defined as a second difference, the developer detecting unit detects the third amount of developer on the basis of a ratio of the second difference to the first difference.

3. The image forming apparatus according to claim 1, wherein the first difference when the first reference value is large is larger than when the first reference value is small.

4. The image forming apparatus according to claim 1, wherein an amount of change in the first difference when a difference between a predetermined value and the first reference value is large is larger than when the difference between the predetermined value and the first reference value is small.

5. The image forming apparatus according to claim 1, wherein the first reference value is set to the output value output when the agitating member is operated for a predetermined period of time or the agitating member rotates a predetermined number of turns.

6. The image forming apparatus according to claim 1, wherein the first reference value is set to the output value output when a predetermined amount of image is formed.

7. The image forming apparatus according to claim 1, further comprising:

an AC power source configured to apply an AC voltage to one of the first electrode and the second electrode,

wherein the output value is a value determined in accordance with a voltage generated in the other of the first electrode and the second electrode by the AC voltage.

8. The image forming apparatus according to claim 1, wherein each of the first wall surface and the second wall surface is an upward sloping surface and extends away from the smallest portion in a horizontal direction.

9. The image forming apparatus according to claim 8, wherein each of the sloping surfaces is a curved surface, and

wherein each of the first electrode and the second electrode is disposed along one of the curved surfaces so as to be in contact with the curved surface.

10. The image forming apparatus according to claim 8, wherein the developer container unit includes a developer bearing member configured to develop an electrostatic latent image formed on an image bearing member.

11. The image forming apparatus according to claim 10, wherein the frame body includes a developing chamber containing the developer bearing member, a developer chamber containing the agitating member, and a partition wall having an opening that allows the developing chamber to communicate with the developer chamber, and

wherein the first wall surface and the second wall surface are disposed in the developer chamber.

12. The image forming apparatus according to claim 11, wherein the smallest portion is located below the developing chamber.

13. The image forming apparatus according to claim 10, wherein the developer detecting unit is capable of detecting the amount of developer by using the output value determined in accordance with a combined capacitance of the capacitance and a capacitance between the first electrode and the developer bearing member.

14. The image forming apparatus according to claim 1, wherein the agitating member rotates so as to pass through the smallest portion.

15. The image forming apparatus according to claim 1, wherein the first electrode and the second electrode are formed of a conductive resin and are formed as sheet members integrated into the frame body.

16. An image forming apparatus comprising:

a developer container unit including

an agitating member configured to rotate and agitate developer,

a first electrode,

a second electrode disposed to face the first electrode with a gap therebetween such that the gap has a smallest portion located below a rotation center of the agitating member and a remote portion wider than the smallest portion and located above the smallest portion, and

a frame body configured to contain the agitating member and the developer and have a first wall surface having the first electrode disposed thereon and a second wall surface having the second electrode disposed thereon; and

a developer detecting unit configured to detect an amount of the developer by using an output value output in accordance with a capacitance formed between the first electrode and the second electrode,

wherein the developer detecting unit corrects the output value on the basis of at least one of a rotational speed of the agitating member, an ambient temperature, an ambient humidity, and a deterioration degree of the developer and detects the amount of developer.

17. The image forming apparatus according to claim 16, wherein the developer detecting unit is capable of detecting a first amount of developer, a second amount of developer that is smaller than the first amount of developer, and a third amount of developer that is smaller than the first amount of developer and larger than the second amount of developer, and

wherein when the output value corresponding to the first amount of developer is defined as a first reference value, a value having a first difference from the first reference value is defined as a second reference value indicating a magnitude of the output value corresponding to the second amount of developer, and a difference between the output value corresponding to the third amount of developer and the first reference value is defined as a second difference, the developer detecting unit detects the third amount of developer on the basis of a ratio of the second difference to the first difference.

18. The image forming apparatus according to claim 17, wherein the correction is performed by varying the ratio.

19. The image forming apparatus according to claim 16, further comprising:

an AC power source configured to apply an AC voltage to one of the first electrode and the second electrode,

wherein the output value is a value determined in accordance with a voltage generated in the other of the first electrode and the second electrode by the AC voltage.

20. The image forming apparatus according to claim 16, wherein each of the first wall surface and the second wall surface is an upward sloping surface and extends away from the smallest portion in a horizontal direction.

21. The image forming apparatus according to claim 20, wherein each of the sloping surfaces is a curved surface, and

wherein each of the first electrode and the second electrode is disposed along one of the curved surfaces so as to be in contact with the curved surface.

22. The image forming apparatus according to claim 20, wherein the developer container unit includes a developer bearing member configured to develop an electrostatic latent image formed on an image bearing member.

23. The image forming apparatus according to claim 22, wherein the frame body includes a developing chamber containing the developer bearing member, a developer chamber containing the agitating member, and a partition wall having an opening that allows the developing chamber to communicate with the developer chamber, and

wherein the first wall surface and the second wall surface are disposed in the developer chamber.

24. The image forming apparatus according to claim 22, wherein the smallest portion is located below a developing chamber.

25. The image forming apparatus according to claim 22, wherein the developer detecting unit is capable of detecting the amount of developer by using the output value determined in accordance with a combined capacitance of the capacitance and a capacitance between the first electrode and the developer bearing member.

26. The image forming apparatus according to claim 22, wherein the correction includes correction based on a deterioration degree of the developer, and

wherein the image forming apparatus further comprises a deterioration estimation unit configured to estimate the deterioration degree of the developer.

27. The image forming apparatus according to claim 26, further comprising:

an exposure device configured to expose an image bearing member and form an electrostatic latent image,

wherein the deterioration estimation unit estimates the deterioration degree of the developer on the basis of at least one of the number of revolutions of the developer bearing member and an exposure time of the exposure device.

28. The image forming apparatus according to claim 16, wherein the agitating member rotates so as to pass through the smallest portion.

29. The image forming apparatus according to claim 16, wherein the first electrode and the second electrode are formed of a conductive resin and are formed as sheet members integrated into the frame body.

30. The image forming apparatus according to claim 16, wherein the correction includes correction based on the rotational speed, and the agitating member is rotatable at a plurality of rotational speeds.

31. The image forming apparatus according to claim 16, wherein the correction includes correction based on one of the ambient temperature and the ambient humidity, and

wherein the image forming apparatus further comprises an environment detection unit configured to detect at least one of temperature and humidity.

32. The image forming apparatus according to claim 16, further comprising:

a storage unit configured to store a correction value used for the correction.

33. The image forming apparatus according to claim 32, wherein the correction value is variable in accordance with the amount of developer.

34. The image forming apparatus according to claim 32, wherein a plurality of types of the developer container units having at least one of different arrangement or shape of the first electrode and the second electrode, the number of the pairs comprising the first electrode and the second electrode, and the amount of developer contained in the frame body are removably mountable, and

wherein the correction value varies depending on one of the arrangement or shape of the first electrode and the second electrode, the number of the pairs consisting of the first electrode and the second electrode, and the amount of developer contained in the frame body.