Heat fixing device and electrophotographic apparatus incorporating the same having a PTC heating element received in a recess of a holder

Claim 2

A heating fixing device, comprising: an endless heat resistant belt; a driving roller for rotating said heat resistant belt; and a holder contactable with said heat resistant belt and having a recess; and a PTC heating element having a positive temperature coefficient characteristic and received in the recess in said holder with an elastic member interposed therebetween.

Claim 3

A heat fixing device, comprising: an endless heat resistant belt; a driving roller for rotating said heat resistant belt; and a holder contactable with said heat resistant belt and having a recess; a PTC heating element having a positive temperature coefficient characteristic and received in the recess in said holder with a heat-insulating and electrically-insulating member interposed therebetween; and an elastic member interposed between said heat-insulating and electrically-insulating member and said recess.

Claim 4

A heat fixing device, comprising: an endless heat resistant belt; a driving roller for rotating said heat resistant belt; and a holder contactable with said heat resistant belt and having a recess; a PTC heating element having a positive temperature coefficient characteristic and received in the recess in said holder with a heat-insulating and electrically-insulating member interposed therebetween; and an elastic member interposed between said heat-insulating and electrically-insulating member and said recess.

Claim 5

A heat fixing device according to claim 1, wherein a radiant plate is attached to a radiant surface of said PTC heating element by means of an adhesive having an excellent thermal conductivity.

Claim 6

A heat fixing device according to claim 2, wherein a radiant plate is attached to a radiant surface of said PTC heating element by means of an adhesive having an excellent thermal conductivity.

Claim 7

A heat fixing device according to claim 3, wherein said radiant plate has a surface abutting on said heat resistant belt and said surface is coated with electrical-insulating material having excellent lubricity.

Claim 8

A heat fixing device according to claim 4, wherein said radiant plate has a surface abutting on said heat resistant belt and said surface is coated with an electrical-insulating material having excellent lubricity.

Claim 9

A heat fixing device according to claim 1, wherein said PTC heating element and said holder having the recess receiving said element form a heating head, and wherein said heating head has a surface contacting said heat resistant belt and said surface is coated with an electrically-insulating material having excellent lubricity.

Claim 10

A heat fixing device according to claim 2, wherein said PTC heating element and said holder having the recess receiving said element form a heating head, and wherein said heating head has a surface contacting said heat resistant belt and said surface is coated with an electrically-insulating material having excellent lubricity.

Claim 11

A heat fixing device according to claim 1, wherein said elastic member has a rubber hardness ranging from 50° to 70°.

Claim 12

A heat fixing device according to claim 2, wherein said elastic member has a rubber hardness ranging from 50° to 70°.

Claim 13

A heat fixing device comprising: an endless heat resistant belt; a driving roller for rotating said heat resistant belt; a holder contactable with said heat resistant belt and having a recess; and a PTC heating element having a positive temperature coefficient characteristic and received in the recess in said holder with a heat-insulating and electrically-insulating member interposed therebetween, wherein said holder is made of an electrically-insulating material.

Claim 14

A heat fixing device comprising: an endless heat resistant belt; a driving roller for rotating said heat resistant belt; a holder contactable with said heat resistant belt and having a recess; and a PTC heating element having a positive temperature coefficient characteristic and received in the recess in said holder with a heat-insulating and electrically-insulating member interposed therebetween, wherein said holder is made of an electrically-insulating material.

Claim 15

A heat fixing device according to claim 1, wherein said holder is made of an electrically-insulating material.

Claim 16

A heat fixing device according to claim 2, wherein said holder is made of an electrically-insulating material.

Claim 17

A heat fixing device according to claim 1, wherein said PTC heating element comprises of chips which are arranged in a row on a radiant plate attached to a radiant surface of said PTC heating element and are received in said recess in said holder.

Claim 18

A heat fixing device according to claim 2, wherein said PTC heating element comprises of chips which are arranged in a row on a radiant plate attached to a radiant surface of said PTC heating element and are received in said recess in said holder.

Claim 19

A heat fixing device according to claim 1, wherein said PTC heating element comprises of chips which are arranged in rows on a radiant plate attached to a radiant surface of said PTC heating element and are received in said recess in said holder.

Claim 20

A heat fixing device according to claim 2, wherein said PTC heating element comprises of chips which are arranged in rows on a radiant plate attached to the radiant surface of said PTC heating element and are received in said recess in said holder.

Claim 21

A heat fixing device according to claim 3, wherein said radiant plate has a convex surface contacting said heat resistant belt.

Claim 22

A heat fixing device according to claim 4, wherein said radiant plate has a convex surface contacting said heat resistant belt.

Claim 23

A heat fixing device, comprising: an endless heat resistant belt; a driving roller for rotating said heat resistant belt; a holder that contacts said heat resistant belt and holds a PTC heating element having a positive temperature coefficient characteristic; a radiant plate attached to a radiant surface of said PTC heating element by an adhesive having excellent thermal conductivity, said PTC heating element having a surface other than the one to which said radiant plate is attached, said other surface being coated with an adiabatic and electrically-insulating material, said PTC heating element being received in a recess formed in said holder with an elastic member interposed therebetween; and a coating of an insulating material having excellent lubricity formed on at least the surface of said radiant plate contacting said heat resistant belt.

Claim 24

A heat fixing device, comprising: an endless heat resistant belt; a driving roller for rotating said heat resistant belt; a holder that contacts said heat resistant belt and holds a PTC heating element having a positive temperature coefficient characteristic; a radiant plate attached to a radiant surface of said PTC heating element by an adhesive having excellent thermal conductivity, said PTC heating element having a surface other than the one to which said radiant plate is attached, said other surface being coated with an adiabatic and electrically-insulating material, said PTC heating element being received in a recess formed in said holder with an elastic member interposed therebetween; and a coating of an insulating material having excellent lubricity formed on at least the surface of said radiant plate contacting said heat resistant belt.

Claim 25

An electrophotographic apparatus, comprising: a photosensitive drum; means for forming an electrostatic latent image on a surface of said photosensitive drum; developing means for developing the electrostatic latent image formed on the surface of said photosensitive drum and producing a toner image; transfer means for transferring the toner image onto a sheet; and heating fixing means for fixing the thus transferred toner image onto said sheet; said heat fixing means comprising a heat fixing device comprising an endless heat resistant belt, a driving roller for rotating said heat resistant belt, a holder contactable with said heat resistant belt and having a recess, and a PTC heating element having a positive temperature coefficient characteristic and received in the recess in said holder with an elastic member interposed therebetween.

Claim 26

An electrophotographic apparatus, comprising: a photosensitive drum; means for forming an electrostatic latent image on a surface of said photosensitive drum; developing means for developing the electrostatic latent image formed on the surface of said photosensitive drum and producing a toner image; transfer means for transferring the toner image onto a sheet; and heating fixing means for fixing the thus transferred toner image onto said sheet; said heat fixing means comprising a heat fixing device comprising an endless heat resistant belt, a driving roller for rotating said heat resistant belt, a holder contactable with said heat resistant belt and having a recess, and a PTC heating element having a positive temperature coefficient characteristic and received in the recess in said holder with an elastic member interposed therebetween.

Claim 27

An electrophotographic apparatus, comprising: a photosensitive drum; means for forming an electrostatic latent image on a surface of said photosensitive drum; developing means for developing the electrostatic latent image formed on the surface of said photosensitive drum and producing a toner image; transfer means for transferring the toner image onto a sheet; and heating fixing means for fixing the thus transferred toner image onto said sheet; said heat fixing means comprising a heat fixing device comprising an endless heat resistant belt, a driving roller for rotating said heat resistant belt, a holder contactable with said heat resistant belt and having a recess, a PTC heating element having a positive temperature coefficient characteristic and received in the recess in said holder with a heat-insulating and electrically-insulating member interposed therebetween, and an elastic member interposed between said heat-insulating and electrically-insulating member and said recess.

Claim 28

An electrophotographic apparatus, comprising: a photosensitive drum; means for forming an electrostatic latent image on a surface of said photosensitive drum; developing means for developing the electrostatic latent image formed on the surface of said photosensitive drum and producing a toner image; transfer means for transferring the toner image onto a sheet; and heating fixing means for fixing the thus transferred toner image onto said sheet; said heat fixing means comprising a heat fixing device comprising an endless heat resistant belt, a driving roller for rotating said heat resistant belt, a holder contactable with said heat resistant belt and having a recess, a PTC heating element having a positive temperature coefficient characteristic and received in the recess in said holder with a heat-insulating and electrically-insulating member interposed therebetween, and an elastic member interposed between said heat-insulating and electrically-insulating member and said recess.

Claim 29

An electrophotographic apparatus, comprising: a photosensitive drum; means for forming an electrostatic latent image on a surface of said photosensitive drum; developing means for developing the electrostatic latent image formed on the surface of said photosensitive drum and producing a toner image; transfer means for transferring the toner image onto a sheet; and heating fixing means for fixing the thus transferred toner image onto said sheet; said heat fixing means comprising a heat fixing device comprising an endless heat resistant belt, a driving roller for rotating said heat resistant belt, a holder that contacts said heat resistant belt and holds a PTC heating element having a positive temperature coefficient characteristic, a radiant plate attached to a radiant surface of said PTC heating element by an adhesive having excellent thermal conductivity, said PTC heating element having a surface other than the one to which said radiant plate is attached, said other surface being coated with an adiabatic and electrically-insulating material, said PTC heating element being received in a recess formed in said holder with an elastic member interposed therebetween, and a coating of an insulating material having excellent lubricity formed on at least the surface of said radiant plate contacting said heat resistant belt.

Claim 30

An electrophotographic apparatus, comprising: a photosensitive drum; means for forming an electrostatic latent image on a surface of said photosensitive drum; developing means for developing the electrostatic latent image formed on the surface of said photosensitive drum and producing a toner image; transfer means for transferring the toner image onto a sheet; and heating fixing means for fixing the thus transferred toner image onto said sheet; said heat fixing means comprising a heat fixing device comprising an endless heat resistant belt, a driving roller for rotating said heat resistant belt, a holder that contacts said heat resistant belt and holds a PTC heating element having a positive temperature coefficient characteristic, a radiant plate attached to a radiant surface of said PTC heating element by an adhesive having excellent thermal conductivity, said PTC heating element having a surface other than the one to which said radiant plate is attached, said other surface being coated with an adiabatic and electrically-insulating material, said PTC heating element being received in a recess formed in said holder with an elastic member interposed therebetween, and a coating of an insulating material having excellent lubricity formed on at least the surface of said radiant plate contacting said heat resistant belt.