IMAGE FORMING APPARATUS AND CONTROL PROGRAM

• US 20170336745A1
• Filed: 04/28/2017
• Published: 11/23/2017
• Est. Priority Date: 05/17/2016
• Status: Active Grant

• Current Assignee: Konica Minolta Inc.
• Original Assignee: Konica Minolta Inc.
• Inventors: WATANABE, Toshifumi
• Granted Patent: US 10,444,691 B2
• Time in Patent Office: Days
• CPC Class Codes: G03G 15/0216 by bringing a charging member into contact with the member to be charged, e.g. roller, brush chargers
• CPC Class Codes: G03G 15/065 Arrangements for controlling the potential of the developing electrode
• CPC Class Codes: G03G 15/5041 Detecting a toner image, e.g. density, toner coverage, using a test patch G03G15/553 takes precedence
• CPC Class Codes: G03G 15/5058 using a test patch
• 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 carrier that carries and transports a latent image; a charging member that is arranged to be in contact with a surface of the image carrier; a developing device that supplies toner to the image carrier and forms a toner image; a density detection unit that detects a density of the toner image; a pattern detection unit that detects a predetermined density variation pattern based on a detection result of the density detection unit according to the toner image; and a determination unit that determines a state of the charging member based on the number of the predetermined density variation patterns detected within a predetermined period of time.

Claims

1. An image forming apparatus comprising:

an image carrier that carries and transports a latent image;

a charging member that is arranged to be in contact with a surface of the image carrier;

a developing device that supplies toner to the image carrier and forms a toner image;

a density detection unit that detects a density of the toner image;

a pattern detection unit that detects a predetermined density variation pattern based on a detection result of the density detection unit according to the toner image; and

a determination unit that determines a state of the charging member based on the number of the predetermined density variation patterns detected within a predetermined period of time.

2. The image forming apparatus according to claim 1, wherein

when the number of the predetermined density variation patterns detected within the period of time exceeds a predetermined number, the determination unit determines that the charging member is at end of life.

3. The image forming apparatus according to claim 1, wherein

the toner image is formed to obtain a uniform density image, and

when the pattern detection unit successively detects a first peak higher than a first density, a second peak lower than the first density, and a third peak higher than the first density in the detection result of the density detection unit according to the toner image, the pattern detection unit detects the density variation as the predetermined density variation pattern.

4. The image forming apparatus according to claim 3, wherein

the first and the third peaks have a peak higher than the first density by a first threshold density or more, and

the second peak has a peak lower than the first density by a second threshold density or more.

5. The image forming apparatus according to claim 3, wherein

the first density includes an average density in a predetermined period of time when the detection result of the density detection unit is within a predetermined density range in the predetermined period of time.

6. The image forming apparatus according to claim 3, wherein

when a difference between a density of at least one of the first and the third peaks and the first density is greater than or equal to a third threshold density, the pattern detection unit detects the difference as the predetermined density variation pattern.

7. The image forming apparatus according to claim 3, wherein

when an inclination of density variation that forms at least one of the first and the third peaks is greater than or equal to a predetermined value, the pattern detection unit detects the inclination as the predetermined density variation pattern.

8. The image forming apparatus according to claim 1, wherein

the image forming apparatus is configured to be able to switch between a normal mode in which an inputted image is printed and a test mode in which a uniform test image is printed and a state of the charging member is determined, and

the pattern detection unit detects the predetermined density variation pattern based on a density variation of the test image.

9. The image forming apparatus according to claim 8, wherein

the image forming apparatus forms the test image on the image carrier by controlling a developing bias voltage and a charging bias voltage applied to the charging member so that an absolute value of the developing bias voltage applied to a developer carrier included in the developing device is higher than an absolute value of a surface potential of the image carrier after being charged by the charging member in the test mode.

10. The image forming apparatus according to claim 8, wherein

the image forming apparatus controls a surface speed of the image carrier in the test mode to be slower than a rotation speed of the image carrier in the normal mode.

11. The image forming apparatus according to claim 8, further comprising:

an image processing unit that reduces image density unevenness by correcting at least one of a developing bias voltage applied to a developer carrier included in the developing device and a charging bias voltage applied to the charging member based on the detection result of the density detection unit in the normal mode.

12. The image forming apparatus according to claim 1, wherein

the density detection unit is arranged to detect the density of the toner image corresponding to a position within a predetermined distance from an end portion in a main scanning direction of the charging member.

13. The image forming apparatus according to claim 12, wherein

the density detection unit is arranged to detect the density of the toner image corresponding to a region where the image forming apparatus is set to be able to perform printing.

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

an intermediate transfer body that receives a toner image formed on the image carrier, wherein

the density detection unit detects a density of a toner image formed on either one of the image carrier and the intermediate transfer body.

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

a display unit that presents information to a user, wherein

when the number of the predetermined density variation patterns detected within the period of time exceeds a predetermined number, a warning is displayed on the display unit.

16. The image forming apparatus according to claim 1, wherein

when the number of the predetermined density variation patterns detected within the period of time exceeds a predetermined number, the determination unit limits a printing operation of the image forming apparatus.

17. A non-transitory recording medium storing a computer readable control program of an image forming apparatus including a charging member that is arranged to be in contact with a surface of an image carrier, the control program causing a computer to execute processing comprising the steps of:

forming a toner image on the image carrier;

detecting a density of the toner image;

detecting a predetermined density variation pattern based on the detected density;

calculating the number of the predetermined density variation patterns detected within a predetermined period of time; and

determining a state of the charging member based on the calculated number of the detected density variation patterns.