Image forming apparatus

• US 7,764,297 B2
• Filed: 08/14/2007
• Issued: 07/27/2010
• Est. Priority Date: 03/12/2003
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation), Toshiba Tec Corporation (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation), Toshiba Tec Corporation (Toshiba Corporation)
• Inventors: Watanabe, Takeshi, Takahashi, Masashi, Aoki, Shinji, Hiroki, Masashi
• Primary Examiner(s): Nguyen; Judy
• Assistant Examiner(s): Hinze; Leo T
• Application Number:
  US11/889,485
• Publication Number:
  US 20070279475A1
• Time in Patent Office: 1,078 Days
• Field of Search: None
• US Class Current: 347/115
• CPC Class Codes: G03G 15/0115 and forming a half-tone image
• CPC Class Codes: G03G 15/0173 plural rotations of recording member to produce multicoloured copy, e.g. rotating set of developing units G03G15/0163 takes precedence
• CPC Class Codes: G03G 15/0189 primary transfer to an intermediate transfer belt G03G15/0184 takes precedence
• CPC Class Codes: G03G 15/0194 primary transfer to the final recording medium G03G15/0184 takes precedence
• CPC Class Codes: G03G 15/0415 and means for controlling illumination or exposure
• CPC Class Codes: G03G 21/0064 using the developing unit, e.g. cleanerless or multi-cycle apparatus
• CPC Class Codes: G03G 2215/0119 Linear arrangement adjacent plural transfer points
• CPC Class Codes: G03G 2215/0164 Uniformity control of the toner density at separate colour transfers
• CPC Class Codes: G03G 2215/0602 Developer

Abstract

There is provided a photoreceptor cleanerless image forming apparatus capable of decreasing color mixture or an exposure error due to reverse transfer toner or untransferred toner.

An image forming apparatus 100 according to the present invention comprises four image forming units 100a, 100b, 100c, and 100d configured to be photoreceptor cleanerless in a 4-drum tandem manner. Each image forming unit includes a photoreceptor 103a, 103b, 103c, or 103d, a charger 105a, 105b, 105c, or 105d, an exposure apparatus 106a, 106b, 106c, or 106d, and a developing apparatus 109a, 109b, 109c, or 109d. When exposure intensities Iy, Ic, Im, and Ik are assumed for exposure sources of the exposure apparatuses in the image forming units which form yellow, magenta, cyan, and black images, respectively, the exposure intensities are configured to satisfy conditions of Ik≧Ic≧Im≧Iy and Ik >Iy. This decreases an exposure error (image hysteresis) in an image formed on paper.

Claims

1. A photoreceptor cleanerless image forming apparatus to overlappingly form yellow, magenta, cyan, and black toner images,

wherein said apparatus includes a control section that is configured to decrease color mixture or exposure error based on controlling a volume-based average particle diameter of toner,

wherein said apparatus comprises four photoreceptor cleanerless developing apparatuses to overlappingly form yellow, magenta, cyan, and black toner images;

and

volume-based average particle diameters Pa, Pb, Pc, and Pd are configured to satisfy conditions of Pa≧

Pb≧

Pc≧

Pd and Pa>

Pd, where Pa, Pb, Pc, and Pd indicate volume-based average particle diameters of toners to be developed on a photoreceptor in the order of development.

2. The image forming apparatus according to claim 1,

wherein each of said photoreceptor cleanerless developing apparatuses includes an image forming unit, and each of said image forming unit is provided with a transfer condition such that the sum of mass per unit area for untransferred toner and reverse transfer toner becomes 100[g/cm²] or less during transfer of a solid image.

3. The image forming apparatus according to claim 1,

wherein each of said photoreceptor cleanerless developing apparatuses includes an exposure apparatus, and an exposure source of said exposure apparatus complies with a red or near-infrared area whose center wavelength is 630 nm or more.

4. The image forming apparatus according to claim 1,

wherein an exposure source of said exposure apparatus is a semiconductor laser.

5. The image forming apparatus according to claim 1,

wherein said image forming apparatus is configured in 4-drum tandem so that four photoreceptor cleanerless image forming units can overlappingly form yellow, magenta, cyan, and black images on a transfer material.

6. The image forming apparatus according to claim 1,

wherein said image forming apparatus is configured in accordance with a 4-rotation system so that four photoreceptor cleanerless developing apparatuses can overlappingly form yellow, magenta, cyan, and black images on an intermediate transferrer, and then these images are transferred onto a transfer material from said intermediate transferrer at a time.

7. A method of overlappingly forming yellow, magenta, cyan, and black toner images using an apparatus comprising four photoreceptor cleanerless developing apparatuses to overlappingly form yellow, magenta, cyan, and black toner images, the method comprising:

decreasing color mixture or exposure error based on controlling a volume-based average particle diameter of toner, wherein volume-based average particle diameters Pa, Pb, Pc, and Pd are configured to satisfy conditions of Pa≧

Pb≧

Pc≧

Pd and Pa>

Pd, where Pa, Pb, Pc, and Pd indicate volume-based average particle diameters of toners to be developed on a photoreceptor in the order of development.

8. The method according to claim 7,

wherein each of said photoreceptor cleanerless developing apparatuses includes an image forming unit, and each of said image forming units is provided with a transfer condition such that the sum of mass per unit area for untransferred toner and reverse transfer toner becomes 100[g/cm²] or less during transfer of a solid image.

9. The method according to claim 7,

wherein each of said photoreceptor cleanerless developing apparatuses includes an exposure apparatus, and an exposure source of said exposure apparatus complies with a red or near-infrared area whose center wavelength is 630 nm or more.

10. The method according to claim 7,

wherein each of said photoreceptor cleanerless developing apparatuses includes an exposure apparatus, and an exposure source of said exposure apparatus is a semiconductor laser.