Image forming method and image forming apparatus

• US 7,396,629 B2
• Filed: 04/26/2005
• Issued: 07/08/2008
• Est. Priority Date: 04/26/2004
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Ishigami, Koh, Okamoto, Naoki, Baba, Yoshinobu, Itakura, Takayuki, Fujikawa, Hiroyuki, Sugahara, Nobuyoshi
• Primary Examiner(s): Goodrow; John L
• Application Number:
  US11/114,058
• Publication Number:
  US 20050244737A1
• Time in Patent Office: 1,169 Days
• Field of Search: 430/120, 430/58.05, 430/120.1
• US Class Current: 430/120.1
• CPC Class Codes: G03G 15/09 using magnetic brush
• CPC Class Codes: G03G 2215/00957 Compositions

Abstract

An image forming method and an image forming apparatus are disclosed in which an electrostatic latent image is formed on a photosensitive member surface by using a two-component developer including a toner and carrier. The photosensitive member surface has a specific modulus of elastic deformation and includes a charge transport layer with a specific thickness. The toner has a specific weight-average particle diameter. The carrier has a specific volume-average particle diameter and a specific circularity, and contains 20% by number or less of particles having a value of “average circularity−2σ” where σ is standard deviation of carrier circularity.

Claims

1. An image forming method comprising at least:

a step for forming an electrostatic latent image on a photosensitive member having at least a charge generation layer on a conductive support and a charge transport layer on the charge generation layer, and

a step for developing the electrostatic latent image by the use of a two-component developer having a toner and a carrier, wherein;

said photosensitive member has a surface having a modulus of elastic deformation of from 46% to 65% and a universal hardness value HU of from 1.5×

10⁸ N/m² to 2.3×

10⁸ N/m², and said charge transport layer has a layer thickness of from 8.0 μ

m to 20.0 μ

m;

said toner has a weight-average particle diameter D4 of from 3.0 μ

m to 10.0 μ

m;

said carrier has a volume-average particle diameter Dv of from 15.0 μ

m to 60.0 μ

m and an average circularity C of from 0.870 to 0.940, and contains 20% by number or less of particles having a value of (average circularity C−

2σ

) or less (σ

is standard deviation of carrier circularity).

2. The image forming method according to claim 1, wherein said carrier comprises carrier core surfaces having been coated with a resin, and the resin contains at least a silicone resin or a fluorine resin.

3. The image forming method according to claim 1, wherein said carrier is a magnetic material dispersed resin carrier having a magnetic material and a binder resin, and said carrier has a true specific gravity of from 3.0 g/cm³ to 4.0 g/cm³ and an intensity of magnetization per carrier volume under 79.6 kA/m, of from 80 kAm²/m³ to 250 kAm²/m³ (emu/cm³).

4. The image forming method according to claim 1, wherein said toner has a weight-average particle diameter D4 of from 4.0 μ

m to 8.0 μ

m and an average circularity of from 0.920 to 1.000.

5. The image forming method according to claim 1, wherein said charge transport layer has a layer thickness of from 8.0 μ

m to 16.0 μ

m.

6. The image forming method according to claim 1, wherein said charge transport layer is divided into a first charge transport layer and a second charge transport layer;

said first charge transport layer being a layer formed of a binder resin in which a charge-transporting material has been dispersed; and

said second charge transport layer being a layer which forms a surface layer and being formed of a curable resin obtained by polymerizing a compound having a polymerizable functional group represented by the following structural formula (1);

7. An image forming apparatus which comprises at least a charging assembly, an exposure unit, developing assemblies having developing rollers and two-component developers, a transfer assembly and a photosensitive member having at least a charge generation layer on a conductive support and a charge transport layer on the charge generation layer, and said two-component developer having a toner and a carrier, wherein;

said photosensitive member has a surface having a modulus of elastic deformation of from 46% to 65% and a universal hardness value HU of from 1.5×

10⁸ N/m² to 2.3×

10⁸ N/m², and said charge transport layer has a layer thickness of from 8.0 μ

m to 20.0 μ

m;

said toner has a weight-average particle diameter D4 of from 3.0 μ

m to 10.0 μ

m;

said carrier has a volume-average particle diameter Dv of from 15.0 μ

m to 60.0 μ

m and an average circularity C of from 0.870 to 0.940, and contains 20% by number or less of particles having a value of (average circularity C−

2σ

) or less (σ

is standard deviation of carrier circularity).

8. The image forming apparatus according to claim 7, wherein said carrier comprises carrier core surfaces having been coated with a resin, and the resin contains at least a silicone resin or a fluorine resin.

9. The image forming apparatus according to claim 7, wherein said carrier is a magnetic material dispersed resin carrier having a magnetic material and a binder resin, and said carrier has a true specific gravity of from 3.0 g/cm³ to 4.0 g/cm³ and an intensity of magnetization per carrier volume under 79.6 kA/m, of from 80 kAm²/m³ to 250 kAm²/m³ (emu/cm³).

10. The image forming apparatus according to claim 7, wherein said toner has a weight-average particle diameter D4 of from 4.0 μ

m to 8.0 μ

m and an average circularity of from 0.920 to 1.000.

11. The image forming apparatus according to claim 7, wherein said charge transport layer has a layer thickness of from 8.0 μ

m to 16.0 μ

m.

12. The image forming apparatus according to claim 7, wherein said charge transport layer is divided into a first charge transport layer and a second charge transport layer;

said first charge transport layer being a layer formed of a binder resin in which a charge-transporting material has been dispersed; and

said second charge transport layer being a layer which forms a surface layer and being formed of a curable resin obtained by polymerizing a compound having a polymerizable functional group represented by the following structural formula (1);