Image-forming method

• US 6,101,358 A
• Filed: 10/15/1999
• Issued: 08/08/2000
• Est. Priority Date: 12/04/1998
• Status: Expired due to Term

• Current Assignee: Fuji Xerox Company Limited (Xerox Holdings Corp.)
• Original Assignee: Fuji Xerox Company Limited (Xerox Holdings Corp.)
• Inventors: Imai, Takashi, Nakazawa, Hiroshi, Iizuka, Akihiro, Iida, Yoshifumi, Ichimura, Masanori
• Primary Examiner(s): Grimley, Arthur T.
• Assistant Examiner(s): Chen, Sophia S.
• Application Number:
  US09/418,826
• Time in Patent Office: 298 Days
• Field of Search: 399/267, 399/252, 399/272, 430/122, 430/120, 430/108, 430/106.6, 430/105
• US Class Current: 430/122.4
• CPC Class Codes: G03G 13/09 using magnetic brush
• CPC Class Codes: G03G 9/08 with toner particles
• CPC Class Codes: G03G 9/107 having magnetic components
• CPC Class Codes: G03G 9/1087 Specified elemental magnetic metal or alloy, e.g. alnico comprising iron, nickel, cobalt, and aluminum, or permalloy comprising iron and nickel

Abstract

Provided is an image-forming method including a step of forming a layer of a developer on a surface of a developer support member disposed facing a latent image support member, a developing step of developing an electrostatic latent image on the latent image support member using the layer of the developer formed to obtain a toner image, a transferring step of transferring the toner image onto a transfer material and a fixing step of fixing the transferred toner image, wherein the developer support member has therein a development magnetic pole in which a magnetic force of a main pole is 100 mT or more, said developer having a toner and a carrier which has a volume average particle diameter of 50 μm or less, and image formation method is conducted at a process speed of 200 mm/sec or more.

In the image-forming method of the invention, high-quality images free from blurring in a half-tone portion adjacent to a solid image can be formed in a high-speed image-forming process using the two-component developer of a small particle diameter without migration of the carrier into the latent image.

Claims

1. An image-forming method comprising the steps of:

forming a layer of a developer on a surface of a developer support member disposed facing a latent image support member;

developing an electrostatic latent image on the latent image support member using the layer of the developer formed to obtain a toner image;

transferring the toner image onto a transfer material; and

fixing the transferred toner image, wherein the developer support member has therein a development magnetic pole in which a magnetic force of a main pole is 100 mT or more, said developer having a toner and a carrier which has a volume average particle diameter of 50 μ

m or less, an image formation method is conducted at a process speed of 200 mm/sec or more, and an electrical resistance of the developer when a toner concentration of the developer is 8% by weight is at least 10⁹ Ω and

at most 10¹² Ω

.

2. The image-forming method of claim 1, said fixed toner image is a multicolor image.

3. The image-forming method of claim 2, said multicolor image is a full color image.

4. The image-forming method of claim 1, wherein a toner coverage of the carrier surface in the developer is 20% or more.

5. The image-forming method of claim 4, wherein the toner coverage of the carrier surface in the developer is at least 20% and at most 70%.

6. The image-forming method of claim 1, wherein the volume average particle diameter of the carrier is between 10 and 50 μ

m.

7. The image-forming method of claim 6, wherein the volume average particle diameter of the carrier is between 15 and 40 μ

m.

8. The image-forming method of claim 1, wherein the carrier is composed of a core material and a resin.

9. The image-forming method of claim 8, said core material has saturation magnetization at 3,000 Oe of 60 emu/g or more.

10. The image-forming method of claim 1, wherein the carrier has electrical resistance which is at least 10⁶ Ω

and at most 10¹² Ω

.

11. The image-forming method of claim 1, wherein the magnetic force of the main pole is 120 mT or more.

12. The image-forming method of claim 1, wherein a toner concentration of the developer is between 4 and 12% by weight.

13. The image-forming method of claim 1, wherein the process speed is 220 mm/sec or more.

14. The image-forming method of claim 1, wherein an amount of the developer on the surface of the developer support member is between 20 and 50 mg/cm².

15. The image-forming method of claim 1, wherein a ratio of circumferential speed of the developer support member to circumferential speed of the latent image support member is between 1.5:

1 and 2.5;

1.

16. The image-forming method of claim 1, wherein a distance between the developer support member and the latent image support member is between 0.2×

10^-3 and 0.4×

10^-3 m.

17. An image-forming apparatus comprising:

forming means for forming a layer of a developer on a surface of a developer support member disposed facing a latent image support member;

developing means for developing an electrostatic latent image on the latent image support member using the layer of the developer formed to obtain a toner image;

transferring means for transferring the toner image onto a transfer material; and

fixing means for fixing the transferred toner image, wherein the developer support member has therein a development magnetic pole in which a magnetic force of a main pole is 100 mT or more, said developer having a toner and a carrier which has volume average particle diameter of 50 μ

m or less, an image formation method is conducted at a process speed of 200 mm/sec or more, and an electrical resistance of the developer when a toner concentration of the developer is 8% by weight is at least 10⁹ Ω and

at most 10¹² Ω

.

18. An image-forming method comprising the steps of:

forming a layer of a developer on a surface of a developer support member disposed facing a latent image support member;

developing an electrostatic latent image on the latent image support member using the layer of the developer formed to obtain a toner image;

transferring the toner image onto a transfer material; and

fixing the transferred toner image, wherein the developer support member has therein a development magnetic pole in which a magnetic force of a main pole is 100 mT or more, said developer having a toner and a carrier which has a volume average particle diameter of 50 μ

m or less, an image formation method is conducted at a process speed of 200 mm/sec or more, the carrier comprising a core material having a saturation magnetization at 3,000 Oe of 60 emu/g or more.