Heating device

• US 5,870,660 A
• Filed: 08/28/1997
• Issued: 02/09/1999
• Est. Priority Date: 08/30/1996
• Status: Expired due to Term

• Current Assignee: Minolta Corporation Limited (Konica Minolta Inc.)
• Original Assignee: Minolta Corporation Limited (Konica Minolta Inc.)
• Inventors: Kato, Takeshi, Oonishi, Taizou, Ito, Tetsuro, Tange, Keigo, Morigami, Yuusuke
• Primary Examiner(s): Smith, Matthew S.
• Application Number:
  US08/919,106
• Time in Patent Office: 530 Days
• Field of Search: 399/328, 399/330, 399/331, 399/333, 219/619, 219/670, 219/671
• US Class Current: 399/330
• CPC Class Codes: G03G 15/2053 Structural details of heat elements, e.g. structure of roller or belt, eddy current, induction heating
• CPC Class Codes: H05B 6/145 Heated rollers

Abstract

A heating device for use in an induction heating type fixing system is composed of a sleeve 12 made of an electrical conductive material and an electromagnet 13 with a coil 20 and a core 18. It is constructed so as to fulfill the following formulas (1), (2), and (3).

S1+S2≧0.3×S3                                  (1)

0.2≦S2/(S1+S2)≦0.8                           (2)

1 mm≦Dmax≦5 mm                               (3)

wherein S1 stands for the cross sectional area of the core 18, S2 for the cross sectional area of the coil 20, S3 for the cross sectional area of the sleeve 12, and Dmax for the maximum distance formed between the outer periphery of the holder 14 and the inner periphery of the sleeve 12.

Claims

1. A heating device comprising:

a sleeve made of an electrical conductive material; and

an electromagnet having a coil and a core;

wherein said heading device satisfies the following formulas (1) and (2),

space="preserve" listing-type="equation">S1+S2≧

0.3×

S3 (1)

space="preserve" listing-type="equation">0.2≦

S2/(S1+S2)≦

0.8 (2)

wherein S1 is cross sectional area of said core, S2 is cross sectional area of said coil, and S3 is cross sectional area defined by an internal surface of said sleeve.

2. A heating device as in claim 1 further comprising:

a holder having a sleeve-like shape and made of dielectric material, said holder being provided in said sleeve to contact at a region of said internal surface of said sleeve, and said holder accommodates said electromagnet therein,

wherein said heating device further satisfies the following formula (3),

space="preserve" listing-type="equation">1 mm≦

Dmax≦

5 mm (3)

wherein Dmax is the maximum distance formed between said holder and said internal surface of said sleeve.

3. A heating device as in claim 1, further comprising a holder which holds said electromagnet.

4. A heating device as in claim 3, wherein said holder is made of a thermosetting resin.

5. A heating device as in claim 4, wherein said holder is hardened.

6. A heating device as in claim 5, wherein said sleeve is heated to a predetermined temperature by an induction heat of said electromagnet, and said holder is hardened in a temperature higher than said predetermined temperature.

7. A heating device as in claim 3, wherein said holder is made of a fiber reinforced resin.

8. A heating device as in claim 3, wherein said holder integrally holds said core and said coil.

9. A heating device as in claim 3, wherein said holder has a region which is in contact with said internal surface of said sleeve.

10. A heating device as in claim 9, wherein said sleeve relatively rotates around said holder.

11. A heating device as in claim 10, wherein said region of said holder is made of a low frictional material.

12. A heating device as in claim 1, wherein said sleeve relatively rotates around said electromagnet.

13. A heating device comprising:

a sleeve made of an electrical conductive material;

an electromagnet having a coil and a core; and

a holder including a first portion and a second portion, said first portion being for electrically insulating said coil from said core and being located between said coil and core, said second portion being for electrically insulating said electromagnet from said sleeve and being located between said electromagnet and said sleeve, said first portion and said second portion being formed as a single member.

14. A heating device as in claim 13, wherein said holder having a region which is in contact with said sleeve.

15. A heating device as claimed in claim 14, wherein said holder is in contact with an internal surface of said sleeve.

16. A heating device as claimed in claim 13, wherein said holder is in contact with an internal surface of said sleeve.

17. A heating device comprising:

a sleeve made of an electrical conductive material;

an electromagnet having a coil and a core; and

a holder for electrically insulating said coil from said core and said electromagnet from said sleeve, said holder including,

a base having an arcuate cross section, and

a pair of plates formed on the base, said base and pair of plates being formed as a single member with the core positioned on the base and between the pair of plates.

18. A heating device comprising:

a sleeve made of an electrical conductive material;

an electromagnet having a coil and a core; and

an insulating member for electrically insulating said coil from said core and said electromagnet from said sleeve, said insulating member being formed by integrally molding the core and the coil.