FIXING DEVICE AND IMAGE FORMING APPARATUS INCLUDING THE FIXING DEVICE

• Main Author: ONISHI SHOTA
• Format: Patent
• Language: English; Japanese
• Published: 19.05.2016
• Subjects: CINEMATOGRAPHY; ELECTROGRAPHY; ELECTROPHOTOGRAPHY; HOLOGRAPHY; MAGNETOGRAPHY; PHOTOGRAPHY; PHYSICS

PROBLEM TO BE SOLVED: To provide a fixing device including a pressure switching mechanism 50 for switching the pressure contact force of both rollers 41 and 42 between a first contact pressure force and a second contact pressure force smaller than the first contact pressure force, the fixing device preventing the contact pressure force of both rollers 41 and 42 from largely deviating from a target value.SOLUTION: While a swing lever 54 is driven by a driving mechanism 50 to a first swing position, the length of a compression coil spring 52 becomes a natural length C0 and the length of an extension coil spring 53 becomes a first predetermined length P1 longer than the natural length, and thereby the pressure contact force of both rollers 41 and 42 becomes a first pressure contact force; whereas while the swing lever 54 is driven by the driving mechanism 50 to a second swing position, the length of the compression coil spring 52 becomes a second predetermined length C1 shorter than its natural length and the length of the extension spring coil 53 becomes a natural length P0, and thereby the pressure contact force of both rollers 41 and 42 becomes a second pressure contact force.SELECTED DRAWING: Figure 4 【課題】両ローラー４１，４２の圧接力を第一圧接力と該第一圧接力よりも小さい第二圧接力とに切換えるための圧切換機構５０を備えた定着装置において、両ローラー４１，４２の圧接力が目標値から大きく外れるのを防止する。【解決手段】駆動機構５０により揺動レバー５４が第一揺動位置に駆動された状態では、圧縮コイルバネ５２が自然長Ｃ０になり且つ引張りコイルバネ５３が自然長よりも長い第一所定長さＰ１になることで、両ローラー４１，４２の圧接力が第一圧接力になる一方、駆動機構５０により揺動レバー５４が第二揺動位置に駆動された状態では、圧縮コイルバネ５２がその自然長よりも短い第二所定長さＣ１になり且つ引張りコイルバネ５３が自然長Ｐ０になることで、両ローラー４１，４２の圧接力が第二圧接力になるようにする。【選択図】図４