JP2005047108A

JP2005047108A - Image erasing device and image forming device

Info

Publication number: JP2005047108A
Application number: JP2003205118A
Authority: JP
Inventors: Takashi Okuma; 孝大隈; Hitoshi Hattori; 仁服部; Kyoji Tsutsui; 恭治筒井; Hideo Sakurai; 秀夫櫻井
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 2003-07-31
Filing date: 2003-07-31
Publication date: 2005-02-24
Anticipated expiration: 2023-07-31
Also published as: JP4286602B2

Abstract

<P>PROBLEM TO BE SOLVED: To correctly grasp a surface temperature of a reversible thermal recording medium in an image erasing device. <P>SOLUTION: The image erasing device is configured such that the surface temperature of a reversible thermal recording paper 2 is detected by a voltage change of a heating element 14 set at a position where the element contacts the reversible thermal recording paper 2 transferred by a transfer part 5. The surface temperature of the reversible thermal recording paper 2 is obtained by the heating element 14 which directly contacts the reversible thermal recording paper 2. Therefore, the surface temperature of the reversible thermal recording paper 2 can be grasped correctly. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、画像消去装置及び画像形成装置に関する。
【０００２】
【従来の技術】
従来、画像消去装置及び画像形成装置の一例として、可逆性感熱記録媒体である可逆性感熱記録紙にリライタブル法で画像を形成するリライタブルプリンタが知られている。このリライタブルプリンタによれば、画像品質は可逆性感熱記録紙を発色させるサーマルヘッド等の仕様に左右され、電子写真プリンタに比べて画像品質が低下する傾向にある。しかしながら、リライタブルプリンタによれば、一枚の可逆性感熱記録紙に対して発色（画像形成）と消色（画像消去）とを繰り返し行えるので、一度印刷を行ってもその印刷を行った可逆性感熱記録紙を再利用することが可能であり、資源の有効利用を図ることができる。
【０００３】
このようなリライタブルプリンタの中には、画像消去動作中に可逆性感熱記録紙を常に画像消去可能な温度範囲である画像消去温度範囲に保持できるようにヒータ基板の保持部やヒータローラ等の可逆性感熱記録紙と接触していない部分の表面温度をサーミスタ等で検知することによって、擬似的に可逆性感熱記録紙の表面温度を検知するプリンタが開示されている（特許文献１参照）。
【０００４】
【特許文献１】
特開平０８−２４４３５９号公報
【０００５】
【発明が解決しようとする課題】
しかしながら、特許文献１の発明では、擬似的に可逆性感熱記録紙の表面温度を検知しているため、可逆性感熱記録紙の表面温度を正確に把握することができず、余裕を持って可逆性感熱記録紙の画像消去温度範囲を設定する必要がある。
【０００６】
また、ヒータ基板の発熱体と可逆性感熱記録紙との間に異物が介在したり、ヒータ基板の発熱体の断線が発生したりするトラブル時には、特許文献１の発明では、ヒータ基板の保持部等の可逆性感熱記録紙と接触していない部分の表面温度をサーミスタ等で検知しているため、上述したようなトラブルによる画像消去不良を生じさせるレベルの温度異常を検出することはできない。
【０００７】
本発明の目的は、可逆性感熱記録媒体の表面温度を正確に把握することができる画像消去装置及び画像形成装置を提供することである。
【０００８】
本発明の目的は、画像消去不良を生じさせるレベルの発熱体の温度異常を検出することができる画像消去装置及び画像形成装置を提供することである。
【０００９】
【課題を解決するための手段】
請求項１記載の発明の画像消去装置は、熱により可逆的に状態が変化する可逆感熱記録層を有する可逆性感熱記録媒体を搬送経路に沿って搬送する搬送部と、前記搬送部により搬送されている前記可逆性感熱記録媒体に接触する位置に設けられ、電気抵抗値が温度に依存して変化する複数の発熱抵抗体からなる発熱体と、前記搬送部により搬送されている前記可逆性感熱記録媒体を加熱する画像消去動作を前記発熱体に実行させるように前記発熱体を駆動制御する加熱駆動手段と、前記発熱体の電圧を検出し、前記搬送部により搬送されている前記可逆性感熱記録媒体の表面温度を検知する温度検知手段と、を具備する。
【００１０】
したがって、発熱体の電圧変化により可逆性感熱記録媒体の表面温度を検知することによって、例えば従来のようなサーミスタ等が不要になる。また、従来、擬似的に可逆性感熱記録媒体の表面温度を推定していたが、可逆性記録媒体に直接接触する発熱体により可逆性感熱記録媒体の表面温度を検知することによって、可逆性感熱記録媒体の表面温度を正確に把握することが可能になる。
【００１１】
請求項２記載の発明は、請求項１記載の画像消去装置において、前記発熱体は複数のブロックに分割されている。
【００１２】
したがって、発熱体を複数のブロックに分割して構成することによって、例えば、可逆性感熱記録媒体の表面温度を発熱体のブロック毎に検出する構成や発熱体による画像消去動作をブロック毎に実行して可逆性感熱記録媒体を部分的に画像消去する構成等にすることが可能になる。
【００１３】
請求項３記載の発明は、請求項２記載の画像消去装置において、前記温度検知手段は複数のブロック毎に前記発熱体の電圧を検出する。
【００１４】
したがって、複数のブロック毎に発熱体の電圧を検出することによって、可逆性記録媒体の表面温度を部分的に検知することが可能になる。
【００１５】
請求項４記載の発明は、請求項２又は３記載の画像消去装置において、前記加熱駆動手段は複数のブロック毎に前記発熱体を駆動制御する。
【００１６】
したがって、複数のブロック毎に発熱体を駆動制御することによって、発熱体による画像消去動作をブロック毎に実行して可逆性感熱記録媒体を部分的に画像消去することが可能になる。
【００１７】
請求項５記載の発明は、請求項４記載の画像消去装置において、前記加熱駆動手段は複数のブロック毎に前記発熱体をブロックの並びに沿って順次駆動制御する。
【００１８】
したがって、複数のブロック毎に前記発熱体をブロックの並びに沿って順次駆動制御することによって、加熱駆動の印加電力を軽減することが可能になる。
【００１９】
請求項６記載の発明は、請求項４記載の画像消去装置において、前記発熱体を支持する支持基板を具備し、前記加熱駆動手段は、前記支持基板の蓄熱効果のばらつきに基づいて、複数のブロック毎に前記発熱体を駆動制御する。
【００２０】
したがって、発熱体を支持する支持基板の蓄熱効果のばらつきに基づいて複数のブロック毎に発熱体を駆動制御することによって、各ブロックにおける不要な加熱駆動を軽減することが可能になる。
【００２１】
請求項７記載の発明は、請求項２ないし５のいずれか一記載の画像消去装置において、前記発熱体を支持する支持基板を具備し、前記発熱体の分割幅は、前記支持基板の蓄熱効果のばらつきに基づいて設定されている。
【００２２】
したがって、発熱体の分割幅を支持基板の蓄熱効果のばらつきに基づいて設定することによって、発熱体の加熱駆動における温度上昇のレスポンスを改善することが可能になる。
【００２３】
請求項８記載の発明は、請求項２ないし７のいずれか一記載の画像消去装置において、前記温度検知手段は、前記搬送部により搬送されている前記可逆性感熱記録媒体の印字不可領域に対向するブロックの前記発熱体の電圧を検出し、前記可逆性感熱記録媒体の印字不可領域の表面温度を検知し、前記加熱駆動手段は、前記温度検知手段により検知された前記可逆性感熱記録媒体の印字不可領域の表面温度に基づいて、前記搬送部により搬送されている前記可逆性感熱記録媒体の印字可能領域に対向するブロックの前記発熱体を駆動制御する。
【００２４】
したがって、可逆性感熱記録媒体の印字不可領域の表面温度を検知し、その表面温度に基づいて可逆性感熱記録媒体の印字可能領域に対向するブロックの発熱体を駆動制御することによって、可逆性感熱記録媒体の印字可能領域を最適温度で加熱し、良好に画像を消去することが可能になる。
【００２５】
請求項９記載の発明は、請求項１ないし８のいずれか一記載の画像消去装置において、前記加熱駆動手段と前記温度検知手段とを所定のタイミングで切り替える切替手段を具備する。
【００２６】
したがって、加熱駆動手段と温度検知手段とを所定のタイミングで切り替えることによって、画像消去に最適な温度で可逆性感熱記録媒体を加熱し、良好な画像消去を行うことが可能になり、さらに、様々な処理を実行することが可能になる。例えば、画像消去動作中でも発熱体を加熱駆動しなくても良いタイミングで加熱駆動手段から温度検出手段に切り替えて、画像消去動作中の可逆性感熱記録媒体の表面温度を常に把握することが可能である。
【００２７】
請求項１０記載の発明は、請求項９記載の画像消去装置において、前記切替手段は、前記発熱体による画像消去動作の際、加熱温度を一定に保つように前記加熱駆動手段と前記温度検知手段とを切り替える。
【００２８】
したがって、発熱体による画像消去動作の際、加熱温度を一定に保つように加熱駆動手段と温度検知手段とを切り替えることによって、画像消去に最適な温度で可逆性感熱記録媒体を加熱し、良好な画像消去を行うことが可能になる。
【００２９】
請求項１１記載の発明は、請求項９又は１０記載の画像消去装置において、前記切替手段は、前記可逆性感熱記録媒体の搬送方向の上流側及び下流側の印字不可領域が前記発熱体に対向する位置を通過する場合、前記温度検知手段を実行させ、前記可逆性感熱記録媒体の印字可能領域が前記発熱体に対向する位置を通過する場合、前記加熱駆動手段を実行させ、前記加熱駆動手段は、前記温度検知手段により検知された前記可逆性感熱記録媒体の上流側及び下流側の印字不可領域の表面温度に基づいて、前記発熱体を駆動制御する。
【００３０】
したがって、可逆性感熱記録媒体の搬送方向の上流側及び下流側の印字不可領域の表面温度を検知し、その表面温度に基づいて発熱体を駆動制御することによって、可逆性感熱記録媒体の印字可能領域を最適温度で加熱し、良好に画像を消去することが可能になる。特に、可逆性感熱記録媒体の先端部の印字不可領域では、印字可能領域での画像消去動作に備えて、可逆性感熱記録媒体の表面温度が画像消去可能な温度範囲に加熱されていることを把握することが可能であり、さらに、可逆性感熱記録媒体の末端部の印字不可領域では、連続印字等における次頁の画像消去動作に備えて、可逆性感熱記録媒体の表面温度が画像消去可能な温度範囲内に維持されていることを把握することが可能である。
【００３１】
請求項１２記載の発明は、請求項１ないし１１のいずれか一記載の画像形成装置において、前記温度検知手段は、前記可逆性感熱記録媒体が前記発熱体に接触していない状態で前記発熱体の電圧を検出して前記発熱体の温度を検知し、前記加熱駆動手段は、前記温度検知手段により検知された前記発熱体の温度に基づいて、前記可逆性感熱記録媒体が画像消去可能な温度範囲に上昇する連続加熱駆動時間を予測し、予測した連続加熱駆動時間に基づいて前記可逆性感熱記録媒体が画像消去可能な温度範囲に達するまで連続で前記発熱体を駆動制御する。
【００３２】
したがって、可逆性感熱記録媒体が発熱体に接触していない状態で発熱体の電圧を検出することによって、起動時等の発熱体の温度を検知することが可能になり、その結果として、ウォームアップに必要な加熱駆動時間も的確に把握することが可能になる。
【００３３】
請求項１３記載の発明は、請求項１ないし１２のいずれか一記載の画像消去装置において、前記温度検知手段は、検知した前記可逆性感熱記録媒体の表面温度が画像消去可能な温度に達しているか否かを判断し、前記加熱駆動手段は、前記温度検知手段により前記可逆性感熱記録媒体の表面温度が画像消去可能な温度に達していると判断された場合、前記発熱体を駆動せず、前記温度検知手段により前記可逆性感熱記録媒体の表面温度が画像消去可能な温度に達していないと判断された場合、前記可逆性感熱記録媒体の表面温度が画像消去可能な温度に達するように前記発熱体及び前記搬送部を駆動制御する。
【００３４】
したがって、温度検知手段により可逆性感熱記録媒体の表面温度が画像消去可能な温度に達していないと判断された場合、発熱体及び搬送部を駆動制御することによって、可逆性感熱記録媒体の表面温度が画像消去可能な温度範囲に達しない状態で画像消去動作を行うような画像消去ミスを防止することが可能になる。
【００３５】
請求項１４記載の発明は、請求項１ないし１３のいずれか一記載の画像消去装置において、前記加熱駆動手段は、前記温度検知手段により検知された前記可逆性感熱記録媒体の表面温度に基づいて、前記可逆性感熱記録媒体の搬送等による温度低下を予測し、不要な加熱を抑制するように前記発熱体を駆動制御する。
【００３６】
したがって、温度検知手段により検知された可逆性感熱記録媒体の表面温度に基づいて、可逆性感熱記録媒体の搬送等による温度低下を予測し、不要な加熱を抑制するように発熱体を駆動制御することによって、不要な加熱駆動に要する印加電力を低減することが可能になる。
【００３７】
請求項１５記載の発明は、請求項１ないし１４のいずれか一記載の画像消去装置において、前記温度検知手段は、前記発熱体の電圧を検出して前記発熱体の温度を検知し、その発熱体の温度を所定の異常温度と比較して前記発熱体が異常な温度状態であるか否かを判断する。
【００３８】
したがって、発熱体の電圧を検出して発熱体の温度を検知し、その発熱体の温度を所定の異常温度と比較し、その比較結果に基づいて発熱体が異常な温度状態であるか否かを判断することによって、発熱体が異常な温度状態であることを検知することが可能になり、その結果として、発熱体と可逆性感熱記録媒体との間に正常な画像消去動作を妨げる異物や発熱体の断線等による画像消去不良及び発熱体の温度異常上昇による事故等の発生を防止することが可能になる。
【００３９】
請求項１６記載の発明は、請求項１５記載の画像消去装置において、前記温度検知手段により前記発熱体が異常な温度状態であると判断された場合、前記発熱体の異常を警告する警告手段を具備する。
【００４０】
したがって、温度検知手段により発熱体が異常な温度状態であると判断された場合、発熱体の異常を警告することによって、装置を停止させる必要性やメンテナンスの必要性等をユーザに知らせることが可能になる。例えば、画像消去品質が悪化する異常レベルであれば、発熱体が異常な温度状態であることを警告ランプ等で報知して、ユーザにメンテナンスの必要性を警告する。
【００４１】
請求項１７記載の発明は、請求項１５又は１６記載の画像消去装置において、前記加熱駆動手段は、前記温度検知手段により前記発熱体が異常な温度状態であると判断された場合、前記発熱体の駆動を停止させる。
【００４２】
したがって、温度検知手段により発熱体が異常な温度状態であると判断された場合、発熱体の駆動を停止させることによって、異常な温度状態である発熱体の駆動が停止し、事故の発生等を防止することが可能になる。
【００４３】
請求項１８記載の発明の画像形成装置は、請求項１ないし１７のいずれか一記載の画像消去装置と、前記画像消去装置が備える搬送部により搬送経路に沿って搬送される可逆性感熱記録媒体に対して画像形成動作を行う画像形成部と、を具備する。
【００４４】
したがって、請求項１ないし１７のいずれか一記載の発明と同様の作用を奏する。
【００４５】
請求項１９記載の発明は、請求項１８記載の画像形成装置において、前記画像消去装置が備える発熱体は前記画像形成部より前記搬送経路の上流側に位置付けられている。
【００４６】
したがって、画像消去装置が備える発熱体を画像形成部より搬送経路の上流側に位置付けることによって、発熱体による画像消去動作後に画像形成部により可逆性感熱記録媒体に画像を形成することが可能になる。
【００４７】
請求項２０記載の発明は、請求項１８又は１９記載の画像形成装置において、前記画像形成部はサーマルヘッドである。
【００４８】
したがって、サーマルヘッドにより画像形成部を構成することによって、簡単な構成で可逆性感熱記録媒体に画像を容易に形成することが可能になる。
【００４９】
【発明の実施の形態】
本発明の実施の一形態について図１ないし図７を参照して説明する。図１は本実施の形態の画像形成装置であるプリンタの内部構造を概略的に示す正面図、図２はプリンタが備える発熱体を概略的に示す平面図である。
【００５０】
プリンタ１は、可逆性感熱記録媒体である可逆性感熱記録紙２を収納する収納部３と、収納部３から可逆性感熱記録紙２を搬送経路である用紙搬送経路４に沿って搬送する搬送部５と、搬送部５により用紙搬送経路４に沿って搬送される可逆性感熱記録紙２に対して画像消去動作を行う画像消去部６と、搬送部５により用紙搬送経路４に沿って搬送される可逆性感熱記録紙２に対して画像形成動作を行う画像形成部７と、用紙搬送経路４に沿って搬送される可逆性感熱記録紙２を検出する検出部であるペーパセンサ８と、から構成されている。なお、ここでは、収納部３、搬送部５及び画像消去部６等から画像消去装置９が構成されている。
【００５１】
搬送部５は、収納部３に収納された可逆性感熱記録紙２を用紙搬送経路４に沿って画像消去部６に供給する供給ローラ１０と、用紙搬送経路４を介して対向するローラ対１１，１２，１３とから構成されている。これらの供給ローラ１０及びローラ対１１，１２，１３は回転自在に保持されている。このような搬送部５は、供給ローラ１０やローラ対１１，１２，１３を回転駆動することにより、可逆性感熱記録紙２を用紙搬送経路４に沿って搬送する。
【００５２】
画像消去部６は、電気抵抗値が温度に依存して変化する発熱抵抗体である発熱素子（図示せず）からなる発熱体１４を支持するヒータ基板１５と、このヒータ基板１５の発熱体１４に対してバネ１６等の押圧力により当接するプラテンローラ１７とから構成されている。
【００５３】
ヒータ基板１５は、用紙搬送経路４に沿って搬送される可逆性感熱記録紙２に発熱体１４が接触する位置に設けられ、さらに、用紙搬送経路４に沿って搬送される可逆性感熱記録紙２に対して平行に設けられている。また、発熱体１４の発熱素子は、可逆性感熱記録紙２の搬送方向に対しほぼ直交してライン状に配列されている。発熱体１４は、可逆性感熱記録紙２の幅とほぼ同じ幅に形成され、複数のブロック１４ａ〜１４ｇに分割されて構成されており、ここでは、例えば７つのブロック１４ａ〜１４ｇに分割されている（図２参照）。
【００５４】
発熱体１４の分割幅は、ヒータ基板１５の蓄熱効果のばらつきを考慮して設定されている。例えば、ヒータ基板１５の中央部の蓄熱効果が高い部分では発熱体１４の分割幅を広くし、ヒータ基板１５の両端部の蓄熱効果が低い部分では発熱体１４の分割幅を狭く設定することで、発熱体１４の加熱駆動における温度上昇のレスポンスを改善することができる。
【００５５】
特に、複数のブロック１４ａ〜１４ｇの両端部に位置するブロック１４ａ，１４ｇの分割幅は、可逆性感熱記録紙２の両端部の印字不可領域Ｒ１の幅とほぼ等しく設定されている。なお、本実施の形態では、可逆性感熱記録紙２において、搬送方向の下流側を先端部、搬送方向の上流側を末端部、搬送方向に向かって両側を両端部としている。ここで、印字不可領域Ｒ１とは、画像が形成されない領域である。印字不可領域Ｒ１は、先端部及び末端部にも存在しており、可逆性感熱記録紙２の中央に位置して画像が形成される印字可能領域Ｒ２を囲むように設けられている。
【００５６】
このような画像消去部６は、画像消去時に発熱体１４を発熱させ、用紙搬送経路４に沿って搬送される可逆性感熱記録紙２に対して画像消去動作を行い、可逆性感熱記録紙２から画像を消去する。また、画像消去部６は、所定のタイミングで、例えば発熱体１４が発熱していない時に、発熱体１４の両端の電圧を検知して可逆性感熱記録紙２の表面温度を検知する。
【００５７】
画像形成部７は、画像データに基づいて発熱する多数の発熱素子（図示せず）を備えるサーマルヘッド１８と、このサーマルヘッド１８に対してバネ１９等の押圧力により当接するプラテンローラ２０とから構成されている。このサーマルヘッド１８の多数の発熱素子は、可逆性感熱記録紙の搬送方向とほぼ直交するようにライン状に配列されている。なお、本実施の形態では、画像形成部７としてサーマルヘッド１８が用いられているが、これに限るものではない。
【００５８】
このような画像形成部７は、画像形成時にサーマルヘッド１８による画像形成動作を行い、用紙搬送経路４に沿って搬送される可逆性感熱記録紙２に画像を形成（記録）する。
【００５９】
ペーパセンサ８は、用紙搬送経路４に沿って搬送される可逆性感熱記録紙２によりそのＯＮ／ＯＦＦ状態が切り替わる位置に配置されており、そのＯＮ／ＯＦＦ状態の変化で用紙搬送経路４に沿って搬送される可逆性感熱記録紙２の通過を検出する。
【００６０】
図３は可逆性感熱記録紙２の内部構造を示す断面図である。可逆性感熱記録紙２は、表面側から順に、保護層２１、可逆的に状態が変化する可逆感熱記録層２２、支持体２３、バックコート層２４を積層して形成されている。この可逆性感熱記録紙２では、表面側から所定の温度で加熱することにより、可逆感熱記録層２２において発色（画像形成）と消色（画像消去）とが可逆的に行われる。すなわち、この可逆性感熱記録紙２は、片面（表面）にのみ画像形成が可能であり、他方の面（裏面）には画像を形成することができない用紙である。そして、可逆性感熱記録紙２は、その表面が発熱体１４及びサーマルヘッド１８に対向して搬送されるように収納部３に収納されている。
【００６１】
図４はプリンタ１が備える各部の電気的接続を概略的に示すブロック図、図５はプリンタ１が備える発熱体１４の電気的接続を概略的に示す平面図である。
【００６２】
プリンタ１は制御回路３０を内蔵し、制御回路３０は、特に図示しないが、各部を集中的に制御するＣＰＵ（ＣｅｎｔｒａｌＰｒｏｃｅｓｓｉｎｇＵｎｉｔ）、ＣＰＵが実行する各種プログラム等を格納するＲＯＭ（ＲｅａｄＯｎｌｙＭｅｍｏｒｙ）、ＣＰＵのワークエリアとして機能するＲＡＭ（ＲａｎｄｏｍＡｃｃｅｓｓＭｅｍｏｒｙ）等から構成されている。
【００６３】
制御回路３０には、サーマルヘッド１８が接続されており、搬送駆動回路３１を介して搬送部５の各種ローラ１０，１１，１２，１３を回転駆動させる搬送モータ３２が接続されている。さらに、制御回路３０には、切替回路３３を介して加熱駆動回路３４及び温度検知回路３５が接続されている。これらの加熱駆動回路３４及び温度検知回路３５には、発熱体１４が接続されている。ここで、切替回路３３が切替手段の一部として機能し、加熱駆動回路３４が加熱駆動手段の一部として機能し、温度検知回路３５が温度検知手段の一部として機能する。加熱駆動回路３４は、発熱体１４を発熱させるための回路であり、発熱体１４のブロック毎に接続されている複数の加熱駆動回路３４ａ〜３４ｇから構成されている（図５参照）。また、温度検知回路３５は、発熱体１４の両端の電圧を検出する回路であり、発熱体１４のブロック毎に接続されている複数の温度検知回路３５ａ〜３５ｇから構成されている（図５参照）。
【００６４】
制御回路３０のＣＰＵは、ＲＯＭに格納されたプログラムにしたがってＲＡＭをワークエリアとして使用しながら、上述したような各部及び全体の制御を司る。また、制御回路３０には、パーソナルコンピュータ等の外部装置（図示せず）が接続されており、この外部装置から画像データが入力される。これらの画像データは、必要な画像処理等を施された後、必要に応じてＲＡＭに格納される。なお本実施の形態では、発熱体１４は、例えば起動時等、そのブロック１４ａ〜１４ｇの並びに沿って順番に順次駆動される。これにより、加熱駆動の印加電力の軽減を実現することができる。
【００６５】
ここで、図６はプリンタ１の内部構造の一部を概略的に示す正面図である。可逆性感熱記録紙２の先端部及び末端部がヒータ基板１５に対向する位置まで搬送されてきたことを検知するには、ペーパセンサ８がＯＮになったタイミングと搬送速度Ｖとに基づいて、ペーパセンサ８からヒータ基板１５までの用紙搬送経路４の長さＬ０、可逆性感熱記録紙２の先端部の印字不可領域Ｒ１の長さＬ１、可逆性感熱記録紙２の印字可能領域Ｒ２の長さＬ２、可逆性感熱記録紙２の末端部の印字不可領域Ｒ１の長さＬ３から、到達時間ｔを算出することが可能である（図１参照）。また、搬送モータ３２としてステッピングモータ等のパルス駆動のモータを用いた場合には、搬送駆動のパルス数をカウントすることでも、用紙搬送経路４上での可逆性感熱記録紙２の位置を検出することが可能である。
【００６６】
なお、本実施の形態においては、ヒータ基板１５の蓄熱効果のばらつきを考慮して発熱体１４の分割幅が設定されているが、これに限るものではなく、例えば発熱体１４の分割幅をある程度小さく設定しておき、ヒータ基板１５の蓄熱効果のばらつきを考慮して、加熱駆動回路３４により発熱体１４をブロック毎に独立して駆動制御することも可能である。これにより、各ブロックにおける不要な加熱駆動を軽減することができる。
【００６７】
このような構成において、制御回路３０のＣＰＵがＲＯＭに格納されたプログラムにしたがって実行する画像消去処理について図７を参照して説明する。図７は本実施の形態の画像消去処理の流れを示すフローチャートである。
【００６８】
プリンタ１は、起動時に、ヒータ基板１５の発熱体１４を連続駆動して画像消去可能な温度範囲である画像消去温度範囲まで上昇させるウォームアップ工程を実行する。このとき、発熱体１４が可逆性感熱記録紙２に接触していない状態で温度検知回路３５により発熱体１４の電圧が検出され、現在の発熱体１４の温度が検知され、画像消去温度範囲に発熱体１４の温度を上昇させる連続駆動時間が予測されて、ウォームアップ工程における温度が制御される。
【００６９】
このウォームアップ工程の完了後、例えば、ユーザによりスタートキー（図示せず）等が押下されると、収納部３に収納された可逆性感熱記録紙２が搬送部５により用紙搬送経路４に沿って搬送される（ステップＳ１）。ペーパセンサ８が可逆性感熱記録紙２を検出してＯＮ状態になり（Ｓ２）、ｔ＝Ｌ０／Ｖ（図６参照）の時間が経過すると（Ｓ３のＹ）、可逆性感熱記録紙２の先端がヒータ基板１５に到達し、切替回路３３の駆動により温度検知回路３５がＯＮ状態に切り替えられ（Ｓ４）、用紙搬送経路４に沿って搬送されている可逆性感熱記録紙２の先端部の印字不可領域Ｒ１の表面温度が検出される。ここに、切替手段としての機能が実現されている。このとき、温度検知回路３５により発熱体１４の電圧を検出することによって、可逆性感熱記録紙２の表面温度が検知される。ここに、温度検知手段としての機能が実現されている。この表面温度の検出は、可逆性感熱記録紙２の先端部の印字可能領域Ｒ２がヒータ基板１５に到達するまで行われる（Ｓ５のＮ）。
【００７０】
この間には、温度検知回路３５により可逆性感熱記録紙２の表面温度が画像消去温度範囲に到達しているか否かが判断される。この画像消去可能な温度範囲に関するデータは制御回路３０のＲＡＭに予め格納されている。温度検知回路３５により可逆性感熱記録紙２の表面温度が画像消去可能な温度に達していると判断された場合には、処理はそのままステップＳ５に進む。
【００７１】
一方、温度検知回路３５により可逆性感熱記録紙２の表面温度が画像消去可能な温度に達していないと判断された場合には、可逆性感熱記録紙２の表面温度が画像消去可能な温度に達するように、加熱駆動回路３４により発熱体１４が駆動制御され、搬送駆動回路３１により搬送部５が駆動制御される。例えば、搬送駆動回路３１により、搬送部５による搬送が停止させられたり、あるいは、その搬送速度が落されたりする。ここに、加熱駆動手段としての機能が実現されている。これにより、可逆性感熱記録紙２の表面温度が画像消去可能な温度範囲に達しない状態で画像消去動作を行うような画像消去ミスを防止することができる。
【００７２】
その後、ｔ＝（Ｌ０＋Ｌ１）／Ｖ（図６参照）の時間が経過すると（Ｓ５のＹ）、可逆性感熱記録紙２の先端部の印字可能領域Ｒ２がヒータ基板１５に到達し、切替回路３３の駆動により、温度検知回路３５がＯＦＦ状態に、加熱駆動回路３４がＯＮ状態に切り替えられる（Ｓ６）。ここに、切替手段としての機能が実現されている。このとき、加熱駆動回路３４により発熱体１４が加熱駆動され、用紙搬送経路４に沿って搬送される可逆性感熱記録紙２から画像が消去される。
ここに、加熱駆動手段としての機能が実現されている。この画像消去動作は、可逆性感熱記録紙２の末端部の印字不可領域Ｒ１がヒータ基板１５に到達するまで行われる（Ｓ７のＮ）。
【００７３】
ｔ＝（Ｌ０＋Ｌ１＋Ｌ２）／Ｖ（図６参照）の時間が経過すると（Ｓ７のＹ）、可逆性感熱記録紙２の末端部の印字不可領域Ｒ１がヒータ基板１５に到達し、切替回路３３の駆動により、温度検知回路３５がＯＮ状態に、加熱駆動回路３４がＯＦＦ状態に切り替えられ（Ｓ８）、用紙搬送経路４に沿って搬送されている可逆性感熱記録紙２の末端部の印字不可領域Ｒ１の表面温度が検出される。ここに、切替手段としての機能が実現されている。このとき、温度検知回路３５により発熱体１４の両端の電圧を検出することによって、可逆性感熱記録紙２の表面温度が検知されている。ここに、温度検知手段としての機能が実現されている。
この表面温度の検出は、可逆性感熱記録紙２の末端がヒータ基板１５に到達するまで行われる（Ｓ９のＮ）。
【００７４】
ｔ＝（Ｌ０＋Ｌ１＋Ｌ２＋Ｌ３）／Ｖ（図６参照）の時間が経過すると（Ｓ９のＹ）、可逆性感熱記録紙２の末端がヒータ基板１５に到達し、切替回路３３の駆動により温度検知回路３５がＯＦＦ状態に切り替えられる（Ｓ１０）。ここに、切替手段としての機能が実現されている。その後、画像形成部７に搬送された可逆性感熱記録紙２は、画像データに基づきサーマルヘッド１８によってその表面に画像が形成される。
【００７５】
このように本実施の形態では、可逆性感熱記録紙２に直接接触する発熱体１４の電圧変化により可逆性感熱記録紙２の表面温度を検知することによって、例えば従来のようなサーミスタ等が不要になる。また、従来、擬似的に可逆性感熱記録紙２の表面温度を推定していたが、可逆性感熱記録紙２に直接接触する発熱体１４により可逆性感熱記録紙２の表面温度を検知することによって、可逆性感熱記録紙２の表面温度を正確に検知することができる。その結果として、可逆性感熱記録紙２の印字可能領域Ｒ２を最適温度で加熱し、良好に画像を消去することができる。
【００７６】
また、可逆性感熱記録紙２の先端部及び末端部の印字不可領域Ｒ１の表面温度を検知し、それらの表面温度に基づいて発熱体１４を駆動制御することによって、可逆性感熱記録紙２の印字可能領域Ｒ２を最適温度で加熱し、良好に画像を消去することができる。特に、可逆性感熱記録紙２の先端部の印字不可領域Ｒ１では、印字可能領域Ｒ２での画像消去動作に備えて可逆性感熱記録紙２の表面温度が画像消去可能な温度範囲に加熱されていることを把握することができ、さらに、可逆性感熱記録紙２の末端部の印字不可領域Ｒ１では、連続印字等における次頁の画像消去動作に備えて可逆性感熱記録紙２の表面温度が画像消去可能な温度範囲内に維持されていることを把握することができる。
【００７７】
なお、本実施の形態においては、画像消去時に、加熱駆動回路３４と温度検知回路３５とを搬送部５による搬送に同期して交互に切り替えることで、可逆性感熱記録紙２の表面温度を画像消去可能な温度範囲内に常時保持する制御を実行することも可能である。これにより、画像消去に最適な温度で可逆性感熱記録紙２を加熱し、良好な画像消去を行うことができる。
【００７８】
また、画像消去時には、常時加熱するのではなく、温度検知回路３５によって可逆性感熱記録紙２の表面温度を検出し、搬送等による温度低下を予測し、次の加熱タイミングで画像消去可能な温度範囲であれば、加熱を不要と判断して、加熱駆動回路３４により発熱体１４を駆動制御することも可能である。これにより、不要な加熱駆動に要する印加電力を低減することができる。
【００７９】
また、搬送されている可逆性感熱記録紙２の印字不可領域Ｒ１に対向するブロックの発熱体１４ａ，１４ｇの電圧を検出して可逆性感熱記録紙２の印字不可領域Ｒ１の表面温度を検知し、その表面温度に基づいて可逆性感熱記録紙２の印字可能領域Ｒ２に対向するブロックの発熱体１４ｂ〜１４ｆを駆動制御することによって、印字可能領域Ｒ２を最適温度で加熱し、良好に画像を消去することができる。
【００８０】
また、可逆性感熱記録紙２とヒータ基板１５との間に正常な画像消去動作を妨げる異物の存在や発熱体１４の断線等による発熱体１４の異常な温度状態、例えば発熱体１４の異常な温度上昇等を温度検知回路３５により検出し、ユーザにランプや警告表示等で警告を促したり、さらには、発熱体１４の加熱駆動を停止したりする制御をできるようにしても良い。例えば、画像消去品質が悪化する異常レベルであれば、発熱体１４の異常な温度状態をランプ等で報知して、ユーザにメンテナンスの必要性を警告し、さらに、異常な温度上昇を検知した場合等には、発熱体１４の駆動を停止させ、事故の発生を防止することができる。ここに、警告手段としての機能が実現されている。
【００８１】
このような場合には、温度検知回路３５により発熱体１４の電圧が検出されて、発熱体１４の温度が検知され、その発熱体１４の温度が所定の異常温度と比較されて発熱体１４が異常な温度状態であるか否かが判断される。本実施の形態では、所定の異常温度は、例えば制御回路３０のＲＡＭに予め格納されている。
【００８２】
【発明の効果】
請求項１記載の発明の画像消去装置によれば、熱により可逆的に状態が変化する可逆感熱記録層を有する可逆性感熱記録媒体を搬送経路に沿って搬送する搬送部と、前記搬送部により搬送されている前記可逆性感熱記録媒体に接触する位置に設けられ、電気抵抗値が温度に依存して変化する複数の発熱抵抗体からなる発熱体と、前記搬送部により搬送されている前記可逆性感熱記録媒体を加熱する画像消去動作を前記発熱体に実行させるように前記発熱体を駆動制御する加熱駆動手段と、前記発熱体の電圧を検出し、前記搬送部により搬送されている前記可逆性感熱記録媒体の表面温度を検知する温度検知手段と、を具備することから、発熱体の電圧変化により可逆性感熱記録媒体の表面温度を検知することによって、例えば従来のようなサーミスタ等が不要になる。また、従来、擬似的に可逆性感熱記録媒体の表面温度を推定していたが、可逆性記録媒体に直接接触する発熱体により可逆性感熱記録媒体の表面温度を検知することによって、可逆性感熱記録媒体の表面温度を正確に把握することができる。
【００８３】
請求項２記載の発明によれば、請求項１記載の画像消去装置において、前記発熱体は複数のブロックに分割されていることから、例えば、可逆性感熱記録媒体の表面温度を発熱体のブロック毎に検出する構成や発熱体による画像消去動作をブロック毎に実行して可逆性感熱記録媒体を部分的に画像消去する構成等にすることができる。
【００８４】
請求項３記載の発明によれば、請求項２記載の画像消去装置において、前記温度検知手段は複数のブロック毎に前記発熱体の電圧を検出することから、可逆性記録媒体の表面温度を部分的に検知することができる。
【００８５】
請求項４記載の発明によれば、請求項２又は３記載の画像消去装置において、前記加熱駆動手段は複数のブロック毎に前記発熱体を駆動制御することから、発熱体による画像消去動作をブロック毎に実行して可逆性感熱記録媒体を部分的に画像消去することができる。
【００８６】
請求項５記載の発明によれば、請求項４記載の画像消去装置において、前記加熱駆動手段は複数のブロック毎に前記発熱体をブロックの並びに沿って順次駆動制御することから、加熱駆動の印加電力を軽減することができる。
【００８７】
請求項６記載の発明によれば、請求項４記載の画像消去装置において、前記発熱体を支持する支持基板を具備し、前記加熱駆動手段は、前記支持基板の蓄熱効果のばらつきに基づいて、複数のブロック毎に前記発熱体を駆動制御することから、各ブロックにおける不要な加熱駆動を軽減することができる。
【００８８】
請求項７記載の発明によれば、請求項２ないし５のいずれか一記載の画像消去装置において、前記発熱体を支持する支持基板を具備し、前記発熱体の分割幅は、前記支持基板の蓄熱効果のばらつきに基づいて設定されていることから、発熱体の加熱駆動における温度上昇のレスポンスを改善することができる。
【００８９】
請求項８記載の発明によれば、請求項２ないし７のいずれか一記載の画像消去装置において、前記温度検知手段は、前記搬送部により搬送されている前記可逆性感熱記録媒体の印字不可領域に対向するブロックの前記発熱体の電圧を検出し、前記可逆性感熱記録媒体の印字不可領域の表面温度を検知し、前記加熱駆動手段は、前記温度検知手段により検知された前記可逆性感熱記録媒体の印字不可領域の表面温度に基づいて、前記搬送部により搬送されている前記可逆性感熱記録媒体の印字可能領域に対向するブロックの前記発熱体を駆動制御することから、可逆性感熱記録媒体の印字可能領域を最適温度で加熱し、良好に画像を消去することができる。
【００９０】
請求項９記載の発明によれば、請求項１ないし８のいずれか一記載の画像消去装置において、前記加熱駆動手段と前記温度検知手段とを所定のタイミングで切り替える切替手段を具備することから、画像消去に最適な温度で可逆性感熱記録媒体を加熱し、良好な画像消去を行うことができ、さらに、様々な処理を実行することができる。例えば、画像消去動作中でも発熱体を加熱駆動しなくても良いタイミングで加熱駆動手段から温度検出手段に切り替えて、画像消去動作中の可逆性感熱記録媒体の表面温度を常に把握することができる。
【００９１】
請求項１０記載の発明によれば、請求項９記載の画像消去装置において、前記切替手段は、前記発熱体による画像消去動作の際、加熱温度を一定に保つように前記加熱駆動手段と前記温度検知手段とを切り替えることから、画像消去に最適な温度で可逆性感熱記録媒体を加熱し、良好な画像消去を行うことができる。
【００９２】
請求項１１記載の発明によれば、請求項９又は１０記載の画像消去装置において、前記切替手段は、前記可逆性感熱記録媒体の搬送方向の上流側及び下流側の印字不可領域が前記発熱体に対向する位置を通過する場合、前記温度検知手段を実行させ、前記可逆性感熱記録媒体の印字可能領域が前記発熱体に対向する位置を通過する場合、前記加熱駆動手段を実行させ、前記加熱駆動手段は、前記温度検知手段により検知された前記可逆性感熱記録媒体の上流側及び下流側の印字不可領域の表面温度に基づいて、前記発熱体を駆動制御することから、可逆性感熱記録媒体の印字可能領域を最適温度で加熱し、良好に画像を消去することができる。特に、可逆性感熱記録媒体の先端部の印字不可領域では、印字可能領域での画像消去動作に備えて、可逆性感熱記録媒体の表面温度が画像消去可能な温度範囲に加熱されていることを把握することができ、さらに、可逆性感熱記録媒体の末端部の印字不可領域では、連続印字等における次頁の画像消去動作に備えて、可逆性感熱記録媒体の表面温度が画像消去可能な温度範囲内に維持されていることを把握することができる。
【００９３】
請求項１２記載の発明によれば、請求項１ないし１１のいずれか一記載の画像形成装置において、前記温度検知手段は、前記可逆性感熱記録媒体が前記発熱体に接触していない状態で前記発熱体の電圧を検出して前記発熱体の温度を検知し、前記加熱駆動手段は、前記温度検知手段により検知された前記発熱体の温度に基づいて、前記可逆性感熱記録媒体が画像消去可能な温度範囲に上昇する連続加熱駆動時間を予測し、予測した連続加熱駆動時間に基づいて前記可逆性感熱記録媒体が画像消去可能な温度範囲に達するまで連続で前記発熱体を駆動制御することから、起動時等の発熱体の温度を検知することが可能になり、その結果として、ウォームアップに必要な加熱駆動時間も的確に把握することができる。
【００９４】
請求項１３記載の発明によれば、請求項１ないし１２のいずれか一記載の画像消去装置において、前記温度検知手段は、検知した前記可逆性感熱記録媒体の表面温度が画像消去可能な温度に達しているか否かを判断し、前記加熱駆動手段は、前記温度検知手段により前記可逆性感熱記録媒体の表面温度が画像消去可能な温度に達していると判断された場合、前記発熱体を駆動せず、前記温度検知手段により前記可逆性感熱記録媒体の表面温度が画像消去可能な温度に達していないと判断された場合、前記可逆性感熱記録媒体の表面温度が画像消去可能な温度に達するように前記発熱体及び前記搬送部を駆動制御することから、可逆性感熱記録媒体の表面温度が画像消去可能な温度範囲に達しない状態で画像消去動作を行うような画像消去ミスを防止することができる。
【００９５】
請求項１４記載の発明によれば、請求項１ないし１３のいずれか一記載の画像消去装置において、前記加熱駆動手段は、前記温度検知手段により検知された前記可逆性感熱記録媒体の表面温度に基づいて、前記可逆性感熱記録媒体の搬送等による温度低下を予測し、不要な加熱を抑制するように前記発熱体を駆動制御することから、不要な加熱駆動に要する印加電力を低減することができる。
【００９６】
請求項１５記載の発明によれば、請求項１ないし１４のいずれか一記載の画像消去装置において、前記温度検知手段は、前記発熱体の電圧を検出して前記発熱体の温度を検知し、その発熱体の温度を所定の異常温度と比較して前記発熱体が異常な温度状態であるか否かを判断することから、発熱体が異常な温度状態であることを検知することが可能になり、その結果として、発熱体と可逆性感熱記録媒体との間に正常な画像消去動作を妨げる異物や発熱体の断線等による画像消去不良及び発熱体の温度異常上昇による事故等の発生を防止することができる。
【００９７】
請求項１６記載の発明によれば、請求項１５記載の画像消去装置において、前記温度検知手段により前記発熱体が異常な温度状態であると判断された場合、前記発熱体の異常を警告する警告手段を具備することから、装置を停止させる必要性やメンテナンスの必要性等をユーザに知らせることができる。例えば、画像消去品質が悪化する異常レベルであれば、発熱体が異常な温度状態であることを警告ランプ等で報知して、ユーザにメンテナンスの必要性を警告することができる。
【００９８】
請求項１７記載の発明によれば、請求項１５又は１６記載の画像消去装置において、前記加熱駆動手段は、前記温度検知手段により前記発熱体が異常な温度状態であると判断された場合、前記発熱体の駆動を停止させることから、異常な温度状態である発熱体の駆動が停止し、事故の発生等を防止することができる。
【００９９】
請求項１８記載の発明の画像形成装置によれば、請求項１ないし１７のいずれか一記載の画像消去装置と、前記画像消去装置が備える搬送部により搬送経路に沿って搬送される可逆性感熱記録媒体に対して画像形成動作を行う画像形成部と、を具備することから、請求項１ないし１７のいずれか一記載の発明と同様の効果を奏する。
【０１００】
請求項１９記載の発明によれば、請求項１８記載の画像形成装置において、前記画像消去装置が備える発熱体は前記画像形成部より前記搬送経路の上流側に位置付けられていることから、発熱体による画像消去動作後に画像形成部により可逆性感熱記録媒体に画像を形成することができる。
【０１０１】
請求項２０記載の発明によれば、請求項１８又は１９記載の画像形成装置において、前記画像形成部はサーマルヘッドであることから、簡単な構成で可逆性感熱記録媒体に画像を容易に形成することができる。
【図面の簡単な説明】
【図１】本発明の実施の一形態の画像形成装置であるプリンタの内部構造を概略的に示す正面図である。
【図２】プリンタが備える発熱体を概略的に示す平面図である。
【図３】可逆性感熱記録紙の内部構造を示す断面図である。
【図４】プリンタが備える各部の電気的接続を概略的に示すブロック図である。
【図５】プリンタが備える発熱体の電気的接続を概略的に示す平面図である。
【図６】プリンタの内部構造の一部を概略的に示す正面図である。
【図７】画像消去処理の流れを示すフローチャートである。
【符号の説明】
１画像形成装置（プリンタ）
２可逆性記録媒体（可逆性感熱記録紙）
４搬送経路（用紙搬送経路）
５搬送部
７画像形成部
９画像消去装置
１４発熱体
１８サーマルヘッド
２２可逆感熱記録層
３４加熱駆動手段（加熱駆動回路）
３５温度検知手段（温度検知回路）
３３切替手段（切替回路）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image erasing apparatus and an image forming apparatus.
[0002]
[Prior art]
Conventionally, as an example of an image erasing apparatus and an image forming apparatus, a rewritable printer that forms an image on a reversible thermosensitive recording paper that is a reversible thermosensitive recording medium by a rewritable method is known. According to this rewritable printer, the image quality depends on the specifications of a thermal head or the like that colors the reversible thermosensitive recording paper, and the image quality tends to be lower than that of the electrophotographic printer. However, according to a rewritable printer, color development (image formation) and color erasure (image erasure) can be repeated on a single reversible thermosensitive recording paper. Thermal recording paper can be reused, and resources can be effectively used.
[0003]
In such a rewritable printer, the reversible thermal recording paper such as the heater substrate holding part and the heater roller can be held in an image erasing temperature range that is a temperature range in which the image can always be erased during an image erasing operation. A printer is disclosed that detects the surface temperature of a reversible thermosensitive recording paper in a pseudo manner by detecting the surface temperature of a portion that is not in contact with the thermal recording paper with a thermistor or the like (see Patent Document 1).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 08-244359
[0005]
[Problems to be solved by the invention]
However, in the invention of Patent Document 1, since the surface temperature of the reversible thermosensitive recording paper is detected in a pseudo manner, the surface temperature of the reversible thermosensitive recording paper cannot be accurately grasped and is reversible with a margin. It is necessary to set the image erasing temperature range of the heat-sensitive recording paper.
[0006]
Further, in the case of a trouble in which foreign matter is present between the heater substrate heating element and the reversible thermosensitive recording paper or the heater substrate heating element is disconnected, in the invention of Patent Document 1, the heater substrate holding portion is provided. Since the surface temperature of the portion that is not in contact with the reversible thermosensitive recording paper or the like is detected by a thermistor or the like, it is not possible to detect a temperature abnormality at a level that causes an image erasure failure due to the above-described trouble.
[0007]
An object of the present invention is to provide an image erasing apparatus and an image forming apparatus that can accurately grasp the surface temperature of a reversible thermosensitive recording medium.
[0008]
An object of the present invention is to provide an image erasing apparatus and an image forming apparatus capable of detecting a temperature abnormality of a heating element at a level causing an image erasing defect.
[0009]
[Means for Solving the Problems]
An image erasing apparatus according to a first aspect of the present invention is a transport unit that transports a reversible thermosensitive recording medium having a reversible thermosensitive recording layer whose state is reversibly changed by heat along a transport path, and is transported by the transport unit. A heating element comprising a plurality of heating resistors provided at a position in contact with the reversible thermosensitive recording medium, the electrical resistance value of which varies depending on temperature, and the reversible thermosensitive sensor being conveyed by the conveying unit. Heating driving means for driving and controlling the heating element so as to cause the heating element to perform an image erasing operation for heating a recording medium, and the reversible thermosensitive sensor that detects the voltage of the heating element and is conveyed by the conveying unit. Temperature detecting means for detecting the surface temperature of the recording medium.
[0010]
Therefore, by detecting the surface temperature of the reversible thermosensitive recording medium by changing the voltage of the heating element, for example, a conventional thermistor or the like becomes unnecessary. Conventionally, the surface temperature of the reversible thermosensitive recording medium has been estimated in a pseudo manner, but the reversible thermosensitive recording medium is detected by detecting the surface temperature of the reversible thermosensitive recording medium with a heating element that directly contacts the reversible recording medium. It becomes possible to accurately grasp the surface temperature of the recording medium.
[0011]
According to a second aspect of the present invention, in the image erasing apparatus according to the first aspect, the heating element is divided into a plurality of blocks.
[0012]
Therefore, by dividing the heating element into a plurality of blocks, for example, the structure for detecting the surface temperature of the reversible thermosensitive recording medium for each block of the heating element and the image erasing operation by the heating element are executed for each block. Thus, the reversible thermosensitive recording medium can be partially erased.
[0013]
According to a third aspect of the present invention, in the image erasing apparatus according to the second aspect, the temperature detecting means detects the voltage of the heating element for each of a plurality of blocks.
[0014]
Therefore, the surface temperature of the reversible recording medium can be partially detected by detecting the voltage of the heating element for each of a plurality of blocks.
[0015]
According to a fourth aspect of the present invention, in the image erasing apparatus according to the second or third aspect, the heating driving unit drives and controls the heating element for each of a plurality of blocks.
[0016]
Therefore, by driving and controlling the heating element for each of a plurality of blocks, it is possible to execute image erasing operation by the heating element for each block and partially erase the image of the reversible thermosensitive recording medium.
[0017]
According to a fifth aspect of the present invention, in the image erasing apparatus according to the fourth aspect, the heating driving means sequentially drives and controls the heating elements along a sequence of blocks for each of a plurality of blocks.
[0018]
Therefore, by sequentially controlling the heating element along the arrangement of the blocks for each of a plurality of blocks, it is possible to reduce the power applied to the heating drive.
[0019]
According to a sixth aspect of the present invention, in the image erasing apparatus according to the fourth aspect of the present invention, the image forming apparatus further includes a support substrate that supports the heating element, and the heating driving unit includes a plurality of heating substrates based on variations in the heat storage effect of the support substrate. The heating element is driven and controlled for each block.
[0020]
Therefore, it is possible to reduce unnecessary heating driving in each block by controlling the driving of the heating element for each of a plurality of blocks based on the variation in the heat storage effect of the support substrate that supports the heating element.
[0021]
A seventh aspect of the present invention is the image erasing apparatus according to any one of the second to fifth aspects, further comprising a support substrate that supports the heating element, wherein the divided width of the heating element is a heat storage effect of the support substrate. It is set based on the variation of.
[0022]
Therefore, by setting the division width of the heating element based on the variation in the heat storage effect of the support substrate, it becomes possible to improve the response to the temperature rise in the heating driving of the heating element.
[0023]
According to an eighth aspect of the present invention, in the image erasing apparatus according to any one of the second to seventh aspects, the temperature detecting unit faces a non-printable area of the reversible thermosensitive recording medium conveyed by the conveying unit. Detecting the surface temperature of the non-printable area of the reversible thermosensitive recording medium, and the heating drive means for detecting the surface temperature of the reversible thermosensitive recording medium detected by the temperature detecting means. Based on the surface temperature of the non-printable area, the heating element of the block facing the printable area of the reversible thermosensitive recording medium conveyed by the conveyance unit is controlled.
[0024]
Therefore, the surface temperature of the non-printable area of the reversible thermosensitive recording medium is detected, and the heating element of the block facing the printable area of the reversible thermosensitive recording medium is driven and controlled based on the surface temperature. The printable area of the recording medium is heated at the optimum temperature, and the image can be erased satisfactorily.
[0025]
According to a ninth aspect of the present invention, in the image erasing apparatus according to any one of the first to eighth aspects, a switching unit that switches the heating driving unit and the temperature detecting unit at a predetermined timing is provided.
[0026]
Therefore, by switching between the heating driving means and the temperature detecting means at a predetermined timing, it becomes possible to heat the reversible thermosensitive recording medium at a temperature optimal for image erasing, and to perform good image erasing. It becomes possible to execute various processes. For example, it is possible to always know the surface temperature of the reversible thermosensitive recording medium during the image erasing operation by switching from the heating driving means to the temperature detecting means at a timing when the heating element does not need to be heated during the image erasing operation. is there.
[0027]
According to a tenth aspect of the present invention, in the image erasing apparatus according to the ninth aspect, the switching unit includes the heating driving unit and the temperature detecting unit so as to keep a heating temperature constant during an image erasing operation by the heating element. And switch.
[0028]
Therefore, during the image erasing operation by the heating element, the reversible thermosensitive recording medium is heated at a temperature optimum for image erasing by switching between the heating driving means and the temperature detecting means so as to keep the heating temperature constant. Image erasing can be performed.
[0029]
According to an eleventh aspect of the present invention, in the image erasing apparatus according to the ninth or tenth aspect, the switching means is configured such that the upstream and downstream unprintable areas in the transport direction of the reversible thermosensitive recording medium face the heating element. If the printable area of the reversible thermosensitive recording medium passes the position facing the heating element, the heating drive means is executed, and the heating drive means is executed. Controls the heating element based on the surface temperatures of the non-printable areas upstream and downstream of the reversible thermosensitive recording medium detected by the temperature detecting means.
[0030]
Therefore, it is possible to print on a reversible thermosensitive recording medium by detecting the surface temperatures of the non-printable areas upstream and downstream in the transport direction of the reversible thermosensitive recording medium, and driving and controlling the heating element based on the surface temperature. It is possible to heat the area at the optimum temperature and erase the image satisfactorily. In particular, in the non-printable area at the tip of the reversible thermosensitive recording medium, the surface temperature of the reversible thermosensitive recording medium is heated to a temperature range in which the image can be erased in preparation for an image erasing operation in the printable area. In addition, in the non-printable area at the end of the reversible thermosensitive recording medium, the surface temperature of the reversible thermosensitive recording medium can be erased in preparation for the image erasing operation on the next page in continuous printing. It is possible to grasp that the temperature is maintained within a certain temperature range.
[0031]
According to a twelfth aspect of the present invention, in the image forming apparatus according to any one of the first to eleventh aspects, the temperature detecting unit is configured to perform the heating element in a state where the reversible thermosensitive recording medium is not in contact with the heating element. The temperature of the heating element is detected by detecting the voltage of the heating element, and the heating drive means is a temperature at which the reversible thermosensitive recording medium can erase an image based on the temperature of the heating element detected by the temperature detection means. The continuous heating driving time rising to the range is predicted, and the heating element is continuously driven and controlled based on the predicted continuous heating driving time until the reversible thermosensitive recording medium reaches a temperature range in which an image can be erased.
[0032]
Therefore, by detecting the voltage of the heating element while the reversible thermosensitive recording medium is not in contact with the heating element, it becomes possible to detect the temperature of the heating element at the time of startup, etc. It is possible to accurately grasp the heating drive time required for the operation.
[0033]
According to a thirteenth aspect of the present invention, in the image erasing apparatus according to any one of the first to twelfth aspects, the temperature detecting unit detects that the detected surface temperature of the reversible thermosensitive recording medium reaches a temperature at which the image can be erased. The heating drive means does not drive the heating element when the temperature detection means determines that the surface temperature of the reversible thermosensitive recording medium has reached an image erasable temperature. When the temperature detecting means determines that the surface temperature of the reversible thermosensitive recording medium has not reached an image erasable temperature, the surface temperature of the reversible thermosensitive recording medium reaches an image erasable temperature. The heating element and the transport unit are driven and controlled.
[0034]
Therefore, when it is determined by the temperature detection means that the surface temperature of the reversible thermosensitive recording medium has not reached the temperature at which the image can be erased, the surface temperature of the reversible thermosensitive recording medium is controlled by driving the heating element and the conveying unit. Therefore, it is possible to prevent an image erasing error such that the image erasing operation is performed in a state where the temperature does not reach the temperature range where the image can be erased.
[0035]
According to a fourteenth aspect of the present invention, in the image erasing apparatus according to any one of the first to thirteenth aspects, the heating driving unit is based on a surface temperature of the reversible thermosensitive recording medium detected by the temperature detecting unit. The temperature reduction due to the conveyance of the reversible thermosensitive recording medium is predicted, and the heating element is driven and controlled to suppress unnecessary heating.
[0036]
Therefore, based on the surface temperature of the reversible thermosensitive recording medium detected by the temperature detecting means, a temperature decrease due to transport of the reversible thermosensitive recording medium is predicted, and the heating element is driven and controlled to suppress unnecessary heating. This makes it possible to reduce the applied power required for unnecessary heating drive.
[0037]
According to a fifteenth aspect of the present invention, in the image erasing apparatus according to any one of the first to fourteenth aspects, the temperature detection unit detects a voltage of the heating element to detect a temperature of the heating element, and the heat generation. The body temperature is compared with a predetermined abnormal temperature to determine whether or not the heating element is in an abnormal temperature state.
[0038]
Therefore, the voltage of the heating element is detected to detect the temperature of the heating element, the temperature of the heating element is compared with a predetermined abnormal temperature, and whether or not the heating element is in an abnormal temperature state based on the comparison result Therefore, it is possible to detect that the heating element is in an abnormal temperature state.As a result, a foreign object that prevents normal image erasing operation between the heating element and the reversible thermosensitive recording medium can be detected. It is possible to prevent the occurrence of an image erasing failure due to disconnection of the heating element and an accident due to abnormal temperature rise of the heating element.
[0039]
According to a sixteenth aspect of the present invention, in the image erasing apparatus according to the fifteenth aspect, when the temperature detecting unit determines that the heating element is in an abnormal temperature state, warning means for warning the abnormality of the heating element is provided. It has.
[0040]
Therefore, when it is determined by the temperature detection means that the heating element is in an abnormal temperature state, it is possible to notify the user of the necessity of stopping the apparatus or the need for maintenance by warning the abnormality of the heating element. become. For example, if the image erasing quality deteriorates to an abnormal level, a warning lamp or the like informs that the heating element is in an abnormal temperature state, and warns the user of the necessity for maintenance.
[0041]
According to a seventeenth aspect of the present invention, in the image erasing apparatus according to the fifteenth or sixteenth aspect, when the heating driving means determines that the heating element is in an abnormal temperature state by the temperature detecting means, the heating element Stop driving.
[0042]
Therefore, when it is determined by the temperature detection means that the heating element is in an abnormal temperature state, by stopping the driving of the heating element, the driving of the heating element in an abnormal temperature state is stopped, and an accident etc. It becomes possible to prevent.
[0043]
An image forming apparatus according to an eighteenth aspect of the present invention is the image erasing apparatus according to any one of the first to seventeenth aspects, and a reversible thermosensitive recording medium that is transported along a transport path by a transport section included in the image erasing apparatus. An image forming unit that performs an image forming operation on the image forming unit.
[0044]
Accordingly, the same effect as the invention according to any one of claims 1 to 17 can be obtained.
[0045]
According to a nineteenth aspect of the present invention, in the image forming apparatus according to the eighteenth aspect, the heating element provided in the image erasing apparatus is positioned upstream of the conveyance path from the image forming unit.
[0046]
Therefore, by positioning the heating element provided in the image erasing apparatus on the upstream side of the conveyance path from the image forming unit, it is possible to form an image on the reversible thermosensitive recording medium by the image forming unit after the image erasing operation by the heating element. .
[0047]
According to a twentieth aspect of the present invention, in the image forming apparatus according to the twentieth or nineteenth aspect, the image forming unit is a thermal head.
[0048]
Therefore, by configuring the image forming unit with a thermal head, it is possible to easily form an image on a reversible thermosensitive recording medium with a simple configuration.
[0049]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a front view schematically showing an internal structure of a printer as an image forming apparatus according to the present embodiment, and FIG. 2 is a plan view schematically showing a heating element provided in the printer.
[0050]
The printer 1 includes a storage unit 3 that stores a reversible thermosensitive recording paper 2 that is a reversible thermosensitive recording medium, and a transport that transports the reversible thermosensitive recording paper 2 from the storage unit 3 along a paper transport path 4 that is a transport path. Unit 5, image erasing unit 6 that performs an image erasing operation on reversible thermosensitive recording paper 2 that is transported along paper transport path 4 by transport unit 5, and transported along paper transport path 4 by transport unit 5 An image forming unit 7 that performs an image forming operation on the reversible thermosensitive recording paper 2 and a paper sensor 8 that is a detection unit that detects the reversible thermosensitive recording paper 2 conveyed along the paper conveyance path 4. It is configured. Here, the image erasing apparatus 9 is constituted by the storage unit 3, the transport unit 5, the image erasing unit 6, and the like.
[0051]
The transport unit 5 includes a supply roller 10 that supplies the reversible thermosensitive recording paper 2 stored in the storage unit 3 to the image erasing unit 6 along the paper transport path 4, and a pair of rollers 11 that face each other via the paper transport path 4. , 12 and 13. The supply roller 10 and the roller pairs 11, 12, 13 are rotatably held. Such a conveyance unit 5 conveys the reversible thermosensitive recording paper 2 along the paper conveyance path 4 by rotationally driving the supply roller 10 and the roller pairs 11, 12, and 13.
[0052]
The image erasing unit 6 includes a heater substrate 15 that supports a heating element 14 including a heating element (not shown) that is a heating resistor whose electric resistance value changes depending on temperature, and the heating element 14 of the heater substrate 15. The platen roller 17 is in contact with the platen roller 17 by the pressing force of the spring 16 or the like.
[0053]
The heater substrate 15 is provided at a position where the heating element 14 contacts the reversible thermosensitive recording paper 2 conveyed along the paper conveyance path 4, and further, the reversible thermosensitive recording paper conveyed along the paper conveyance path 4. 2 in parallel. The heating elements of the heating element 14 are arranged in a line substantially orthogonal to the transport direction of the reversible thermosensitive recording paper 2. The heating element 14 is formed to have substantially the same width as the width of the reversible thermosensitive recording paper 2 and is divided into a plurality of blocks 14a to 14g. Here, for example, the heating element 14 is divided into seven blocks 14a to 14g. (See FIG. 2).
[0054]
The division width of the heating element 14 is set in consideration of variations in the heat storage effect of the heater substrate 15. For example, by dividing the heating element 14 at the central portion of the heater substrate 15 where the heat storage effect is high, the dividing width of the heating element 14 is set narrow at the portion where the heat storage effect at both ends of the heater substrate 15 is low. In addition, it is possible to improve the response of the temperature rise in the heating drive of the heating element 14.
[0055]
In particular, the division widths of the blocks 14 a and 14 g located at both ends of the plurality of blocks 14 a to 14 g are set to be approximately equal to the width of the non-printable area R 1 at both ends of the reversible thermosensitive recording paper 2. In the present embodiment, in the reversible thermosensitive recording paper 2, the downstream side in the transport direction is the leading end, the upstream side in the transport direction is the end, and both sides in the transport direction are both ends. Here, the non-printable region R1 is a region where no image is formed. The non-printable area R1 is also present at the front end and the end, and is provided at the center of the reversible thermosensitive recording paper 2 so as to surround the printable area R2 where an image is formed.
[0056]
The image erasing unit 6 causes the heating element 14 to generate heat when erasing the image, performs an image erasing operation on the reversible thermosensitive recording paper 2 conveyed along the paper conveyance path 4, and reversible thermosensitive recording paper 2. Erase images from. Further, the image erasing unit 6 detects the surface temperature of the reversible thermosensitive recording paper 2 by detecting the voltage at both ends of the heating element 14 at a predetermined timing, for example, when the heating element 14 is not generating heat.
[0057]
The image forming unit 7 includes a thermal head 18 having a large number of heating elements (not shown) that generate heat based on image data, and a platen roller 20 that contacts the thermal head 18 by a pressing force of a spring 19 or the like. It is configured. A number of heating elements of the thermal head 18 are arranged in a line so as to be substantially orthogonal to the transport direction of the reversible thermosensitive recording paper. In the present embodiment, the thermal head 18 is used as the image forming unit 7, but the present invention is not limited to this.
[0058]
Such an image forming unit 7 forms (records) an image on the reversible thermosensitive recording paper 2 transported along the paper transport path 4 by performing an image forming operation by the thermal head 18 during image formation.
[0059]
The paper sensor 8 is disposed at a position where the ON / OFF state is switched by the reversible thermosensitive recording paper 2 conveyed along the paper conveyance path 4, and along the paper conveyance path 4 due to the change in the ON / OFF state. The passage of the reversible thermosensitive recording paper 2 being conveyed is detected.
[0060]
FIG. 3 is a sectional view showing the internal structure of the reversible thermosensitive recording paper 2. The reversible thermosensitive recording paper 2 is formed by laminating a protective layer 21, a reversible thermosensitive recording layer 22 whose state changes reversibly, a support 23, and a backcoat layer 24 in order from the surface side. In the reversible thermosensitive recording paper 2, coloring (image formation) and decoloring (image erasing) are performed reversibly in the reversible thermosensitive recording layer 22 by heating from the surface side at a predetermined temperature. That is, the reversible thermosensitive recording paper 2 is a paper on which an image can be formed only on one side (front side) and an image cannot be formed on the other side (back side). The reversible thermosensitive recording paper 2 is stored in the storage unit 3 so that the surface of the reversible thermosensitive recording paper 2 is conveyed facing the heating element 14 and the thermal head 18.
[0061]
FIG. 4 is a block diagram schematically showing the electrical connection of each part provided in the printer 1, and FIG. 5 is a plan view schematically showing the electrical connection of the heating element 14 provided in the printer 1.
[0062]
The printer 1 includes a control circuit 30. Although not particularly illustrated, the control circuit 30 includes a central processing unit (CPU) that centrally controls each unit and a ROM (read only memory) that stores various programs executed by the CPU. , And a RAM (Random Access Memory) that functions as a work area of the CPU.
[0063]
A thermal head 18 is connected to the control circuit 30, and a conveyance motor 32 that rotationally drives the various rollers 10, 11, 12, and 13 of the conveyance unit 5 is connected via a conveyance drive circuit 31. Further, a heating drive circuit 34 and a temperature detection circuit 35 are connected to the control circuit 30 via a switching circuit 33. The heating element 14 is connected to the heating drive circuit 34 and the temperature detection circuit 35. Here, the switching circuit 33 functions as a part of the switching unit, the heating drive circuit 34 functions as a part of the heating drive unit, and the temperature detection circuit 35 functions as a part of the temperature detection unit. The heating drive circuit 34 is a circuit for causing the heating element 14 to generate heat, and includes a plurality of heating drive circuits 34a to 34g connected to each block of the heating element 14 (see FIG. 5). The temperature detection circuit 35 is a circuit that detects the voltage across the heating element 14, and includes a plurality of temperature detection circuits 35a to 35g connected to each block of the heating element 14 (see FIG. 5). ).
[0064]
The CPU of the control circuit 30 controls the respective units and the whole as described above while using the RAM as a work area in accordance with a program stored in the ROM. The control circuit 30 is connected to an external device (not shown) such as a personal computer, and image data is input from the external device. These image data are subjected to necessary image processing and the like, and then stored in the RAM as necessary. In the present embodiment, the heating element 14 is sequentially driven in order along the arrangement of the blocks 14a to 14g, for example, at the time of activation. Thereby, reduction of the applied power of heating drive can be realized.
[0065]
Here, FIG. 6 is a front view schematically showing a part of the internal structure of the printer 1. In order to detect that the leading edge and the trailing edge of the reversible thermosensitive recording paper 2 have been conveyed to a position facing the heater substrate 15, the paper sensor is based on the timing when the paper sensor 8 is turned on and the conveying speed V. The length L0 of the sheet conveyance path 4 from 8 to the heater substrate 15, the length L1 of the non-printable area R1 at the tip of the reversible thermosensitive recording paper 2, and the length L2 of the printable area R2 of the reversible thermosensitive recording paper 2 The arrival time t can be calculated from the length L3 of the non-printable area R1 at the end of the reversible thermosensitive recording paper 2 (see FIG. 1). When a pulse-driven motor such as a stepping motor is used as the transport motor 32, the position of the reversible thermosensitive recording paper 2 on the paper transport path 4 is also detected by counting the number of transport drive pulses. It is possible.
[0066]
In the present embodiment, the division width of the heating element 14 is set in consideration of the variation in the heat storage effect of the heater substrate 15. However, the present invention is not limited to this. For example, the division width of the heating element 14 is set to some extent. The heating element 14 can be driven and controlled independently for each block by the heating drive circuit 34 in consideration of variations in the heat storage effect of the heater substrate 15. Thereby, the unnecessary heating drive in each block can be reduced.
[0067]
An image erasing process executed by the CPU of the control circuit 30 in accordance with a program stored in the ROM in such a configuration will be described with reference to FIG. FIG. 7 is a flowchart showing the flow of the image erasing process of the present embodiment.
[0068]
When the printer 1 is started up, it performs a warm-up process in which the heating element 14 of the heater substrate 15 is continuously driven to raise the image erasing temperature range, which is a temperature range where image erasing is possible. At this time, the voltage of the heating element 14 is detected by the temperature detection circuit 35 in a state where the heating element 14 is not in contact with the reversible thermosensitive recording paper 2, the current temperature of the heating element 14 is detected, and the image erasing temperature range is reached. The continuous driving time for raising the temperature of the heating element 14 is predicted, and the temperature in the warm-up process is controlled.
[0069]
After the warm-up process is completed, for example, when a user presses a start key (not shown) or the like, the reversible thermosensitive recording paper 2 stored in the storage unit 3 is moved along the paper transport path 4 by the transport unit 5. (Step S1). When the paper sensor 8 detects the reversible thermosensitive recording paper 2 and is turned on (S2), and t = L0 / V (see FIG. 6) has elapsed (Y in S3), the leading edge of the reversible thermosensitive recording paper 2 is reached. Reaches the heater substrate 15, the temperature detection circuit 35 is switched to the ON state by driving the switching circuit 33 (S 4), and the leading end of the reversible thermosensitive recording paper 2 being conveyed along the paper conveyance path 4 is printed. The surface temperature of the impossible region R1 is detected. Here, a function as switching means is realized. At this time, the surface temperature of the reversible thermosensitive recording paper 2 is detected by detecting the voltage of the heating element 14 by the temperature detection circuit 35. Here, the function as the temperature detecting means is realized. The surface temperature is detected until the printable area R2 at the leading end of the reversible thermosensitive recording paper 2 reaches the heater substrate 15 (N in S5).
[0070]
During this time, the temperature detection circuit 35 determines whether or not the surface temperature of the reversible thermosensitive recording paper 2 has reached the image erasing temperature range. Data relating to the temperature range where the image can be erased is stored in the RAM of the control circuit 30 in advance. If it is determined by the temperature detection circuit 35 that the surface temperature of the reversible thermosensitive recording paper 2 has reached an image erasable temperature, the process proceeds directly to step S5.
[0071]
On the other hand, if it is determined by the temperature detection circuit 35 that the surface temperature of the reversible thermosensitive recording paper 2 has not reached the temperature at which the image can be erased, the surface temperature of the reversible thermosensitive recording paper 2 becomes the temperature at which the image can be erased. The heating element 14 is driven and controlled by the heating drive circuit 34, and the conveyance unit 5 is driven and controlled by the conveyance drive circuit 31. For example, the transport by the transport unit 5 is stopped by the transport drive circuit 31, or the transport speed is decreased. Here, the function as the heating drive means is realized. Thereby, it is possible to prevent an image erasing error such that an image erasing operation is performed in a state where the surface temperature of the reversible thermosensitive recording paper 2 does not reach the temperature range in which the image can be erased.
[0072]
Thereafter, when the time t = (L0 + L1) / V (see FIG. 6) elapses (Y in S5), the printable region R2 at the leading end of the reversible thermosensitive recording paper 2 reaches the heater substrate 15, and the switching circuit 33 As a result, the temperature detection circuit 35 is switched to the OFF state and the heating drive circuit 34 is switched to the ON state (S6). Here, a function as switching means is realized. At this time, the heating element 14 is heated by the heating drive circuit 34, and the image is erased from the reversible thermosensitive recording paper 2 conveyed along the paper conveyance path 4.
Here, the function as the heating drive means is realized. This image erasing operation is performed until the non-printable area R1 at the end of the reversible thermosensitive recording paper 2 reaches the heater substrate 15 (N in S7).
[0073]
When the time t = (L0 + L1 + L2) / V (see FIG. 6) has elapsed (Y in S7), the non-printable area R1 at the end of the reversible thermosensitive recording paper 2 reaches the heater substrate 15 and the switching circuit 33 is driven. As a result, the temperature detection circuit 35 is switched to the ON state and the heating drive circuit 34 is switched to the OFF state (S8), and the unprintable region R1 at the end of the reversible thermosensitive recording paper 2 being conveyed along the paper conveyance path 4 The surface temperature of is detected. Here, a function as switching means is realized. At this time, the surface temperature of the reversible thermosensitive recording paper 2 is detected by detecting the voltage across the heating element 14 by the temperature detection circuit 35. Here, the function as the temperature detecting means is realized.
The surface temperature is detected until the end of the reversible thermosensitive recording paper 2 reaches the heater substrate 15 (N in S9).
[0074]
When the time t = (L0 + L1 + L2 + L3) / V (see FIG. 6) elapses (Y in S9), the end of the reversible thermosensitive recording paper 2 reaches the heater substrate 15, and the temperature detection circuit 35 is driven by the switching circuit 33 being driven. It is switched to the OFF state (S10). Here, a function as switching means is realized. Thereafter, an image is formed on the surface of the reversible thermosensitive recording paper 2 conveyed to the image forming unit 7 by the thermal head 18 based on the image data.
[0075]
As described above, in this embodiment, by detecting the surface temperature of the reversible thermosensitive recording paper 2 based on the voltage change of the heating element 14 that directly contacts the reversible thermosensitive recording paper 2, for example, a conventional thermistor or the like is not required. become. Conventionally, the surface temperature of the reversible thermosensitive recording paper 2 has been estimated in a pseudo manner, but the surface temperature of the reversible thermosensitive recording paper 2 is detected by the heating element 14 that directly contacts the reversible thermosensitive recording paper 2. Thus, the surface temperature of the reversible thermosensitive recording paper 2 can be accurately detected. As a result, the printable area R2 of the reversible thermosensitive recording paper 2 can be heated at the optimum temperature, and the image can be erased satisfactorily.
[0076]
Further, by detecting the surface temperature of the non-printable region R1 at the leading end and the terminal end of the reversible thermosensitive recording paper 2, and controlling the driving of the heating element 14 based on those surface temperatures, the reversible thermosensitive recording paper 2 The printable area R2 can be heated at the optimum temperature to erase the image satisfactorily. In particular, in the non-printable area R1 at the leading end of the reversible thermosensitive recording paper 2, the surface temperature of the reversible thermosensitive recording paper 2 is heated to a temperature range in which the image can be erased in preparation for an image erasing operation in the printable area R2. Further, in the non-printable area R1 at the end of the reversible thermosensitive recording paper 2, the surface temperature of the reversible thermosensitive recording paper 2 is prepared for the image erasing operation on the next page in continuous printing or the like. It can be ascertained that the temperature is maintained within a temperature range where the image can be erased.
[0077]
In the present embodiment, the surface temperature of the reversible thermosensitive recording paper 2 is changed by alternately switching the heating drive circuit 34 and the temperature detection circuit 35 in synchronization with the conveyance by the conveyance unit 5 at the time of erasing the image. It is also possible to execute control that keeps the temperature constantly within the erasable temperature range. As a result, the reversible thermosensitive recording paper 2 can be heated at a temperature optimal for image erasure, and good image erasure can be performed.
[0078]
At the time of image erasing, instead of constantly heating, the temperature detection circuit 35 detects the surface temperature of the reversible thermosensitive recording paper 2 to predict a temperature drop due to conveyance or the like, and the temperature at which the image can be erased at the next heating timing If it is within the range, it is possible to determine that heating is unnecessary, and to drive and control the heating element 14 by the heating drive circuit 34. Thereby, the applied electric power required for unnecessary heating drive can be reduced.
[0079]
Further, the surface temperature of the non-printable area R1 of the reversible thermosensitive recording paper 2 is detected by detecting the voltage of the heating elements 14a and 14g of the blocks facing the non-printable area R1 of the reversible thermosensitive recording paper 2 being conveyed. Based on the surface temperature, the printable area R2 is heated at the optimum temperature by driving and controlling the heating elements 14b to 14f of the block facing the printable area R2 of the reversible thermosensitive recording paper 2, and a good image is obtained. Can be erased.
[0080]
Also, an abnormal temperature state of the heating element 14 due to the presence of foreign matter that hinders normal image erasing operation or disconnection of the heating element 14 between the reversible thermosensitive recording paper 2 and the heater substrate 15, for example, an abnormal condition of the heating element 14. A temperature rise or the like may be detected by the temperature detection circuit 35, and the user may be prompted to give a warning by a lamp or warning display, or may be controlled to stop the heating drive of the heating element 14. For example, if the image erasing quality deteriorates at an abnormal level, the abnormal temperature state of the heating element 14 is notified by a lamp or the like, the user is warned of the need for maintenance, and an abnormal temperature rise is detected. For example, the driving of the heating element 14 can be stopped to prevent the occurrence of an accident. Here, a function as a warning means is realized.
[0081]
In such a case, the voltage of the heating element 14 is detected by the temperature detection circuit 35, the temperature of the heating element 14 is detected, the temperature of the heating element 14 is compared with a predetermined abnormal temperature, and the heating element 14 is It is determined whether or not the temperature is abnormal. In the present embodiment, the predetermined abnormal temperature is stored in advance in the RAM of the control circuit 30, for example.
[0082]
【The invention's effect】
According to the image erasing apparatus of the first aspect of the present invention, the transport unit transports the reversible thermosensitive recording medium having the reversible thermosensitive recording layer whose state is reversibly changed by heat along the transport path, and the transport unit. A heating element that is provided at a position in contact with the reversible thermosensitive recording medium being conveyed and has a plurality of heating resistors whose electric resistance values change depending on temperature, and the reversible that is conveyed by the conveying unit Heating drive means for driving and controlling the heating element so as to cause the heating element to perform an image erasing operation for heating the sexual thermosensitive recording medium, and the reversible being detected by the voltage of the heating element and conveyed by the conveying unit. Temperature detecting means for detecting the surface temperature of the heat-sensitive recording medium. Therefore, by detecting the surface temperature of the reversible heat-sensitive recording medium by changing the voltage of the heating element, for example, a conventional temperature sensor can be used. Mista, etc. is not required. Conventionally, the surface temperature of the reversible thermosensitive recording medium has been estimated in a pseudo manner, but the reversible thermosensitive recording medium is detected by detecting the surface temperature of the reversible thermosensitive recording medium with a heating element that directly contacts the reversible recording medium. The surface temperature of the recording medium can be accurately grasped.
[0083]
According to a second aspect of the present invention, in the image erasing apparatus according to the first aspect, since the heating element is divided into a plurality of blocks, for example, the surface temperature of the reversible thermosensitive recording medium is set to a block of the heating element. A configuration in which the image is detected every time, an image erasing operation by a heating element is executed for each block, and a reversible thermosensitive recording medium can be partially erased.
[0084]
According to a third aspect of the present invention, in the image erasing apparatus according to the second aspect, since the temperature detecting unit detects the voltage of the heating element for each of a plurality of blocks, the surface temperature of the reversible recording medium is partially set. Can be detected automatically.
[0085]
According to a fourth aspect of the present invention, in the image erasing apparatus according to the second or third aspect, since the heating driving unit drives and controls the heating element for each of a plurality of blocks, the image erasing operation by the heating element is blocked. It can be executed every time to partially erase the image of the reversible thermosensitive recording medium.
[0086]
According to a fifth aspect of the present invention, in the image erasing apparatus according to the fourth aspect, the heating driving means sequentially drives and controls the heating elements along the arrangement of the blocks for each of a plurality of blocks. Electric power can be reduced.
[0087]
According to the invention of claim 6, in the image erasing apparatus according to claim 4, the image erasing apparatus includes a support substrate that supports the heating element, and the heating driving unit is based on variation in a heat storage effect of the support substrate. Since the heating element is driven and controlled for each of a plurality of blocks, unnecessary heating driving in each block can be reduced.
[0088]
According to a seventh aspect of the present invention, in the image erasing apparatus according to any one of the second to fifth aspects, the apparatus includes a support substrate that supports the heating element, and the divided width of the heating element is equal to that of the support substrate. Since it is set based on variation in the heat storage effect, it is possible to improve the response of the temperature rise in the heating drive of the heating element.
[0089]
According to an eighth aspect of the present invention, in the image erasing apparatus according to any one of the second to seventh aspects, the temperature detecting means is a non-printable area of the reversible thermosensitive recording medium conveyed by the conveying unit. And detecting the surface temperature of the non-printable area of the reversible thermosensitive recording medium, and the heating driving means detects the reversible thermosensitive recording detected by the temperature detecting means. Based on the surface temperature of the non-printable area of the medium, the heating element of the block facing the printable area of the reversible thermosensitive recording medium transported by the transport section is driven and controlled, so that the reversible thermosensitive recording medium The printable area is heated at the optimum temperature, and the image can be erased satisfactorily.
[0090]
According to the ninth aspect of the present invention, the image erasing apparatus according to any one of the first to eighth aspects further includes a switching unit that switches the heating driving unit and the temperature detecting unit at a predetermined timing. The reversible thermosensitive recording medium can be heated at a temperature optimal for image erasing to perform good image erasing, and various processes can be performed. For example, it is possible to always grasp the surface temperature of the reversible thermosensitive recording medium during the image erasing operation by switching from the heating driving means to the temperature detecting means at a timing that does not require the heating element to be heated during the image erasing operation.
[0091]
According to a tenth aspect of the present invention, in the image erasing apparatus according to the ninth aspect, the switching means and the heating driving means and the temperature so as to keep a heating temperature constant during an image erasing operation by the heating element. Since the detection means is switched, the reversible thermosensitive recording medium can be heated at a temperature optimal for image erasure, and good image erasure can be performed.
[0092]
According to an eleventh aspect of the present invention, in the image erasing apparatus according to the ninth or tenth aspect, the switching means is configured such that the upstream and downstream unprintable areas in the transport direction of the reversible thermosensitive recording medium have the heating element. If the printable area of the reversible thermosensitive recording medium passes the position facing the heating element, the heating drive means is executed, and the heating detection means is executed. Since the driving means controls the heating element based on the surface temperatures of the non-printable areas upstream and downstream of the reversible thermosensitive recording medium detected by the temperature detecting means, the reversible thermosensitive recording medium The printable area is heated at the optimum temperature, and the image can be erased satisfactorily. In particular, in the non-printable area at the tip of the reversible thermosensitive recording medium, the surface temperature of the reversible thermosensitive recording medium is heated to a temperature range in which the image can be erased in preparation for an image erasing operation in the printable area. Furthermore, in the non-printable area at the end of the reversible thermosensitive recording medium, the surface temperature of the reversible thermosensitive recording medium is the temperature at which the image can be erased in preparation for the image erasing operation on the next page in continuous printing or the like. It can be grasped that it is maintained within the range.
[0093]
According to a twelfth aspect of the present invention, in the image forming apparatus according to any one of the first to eleventh aspects, the temperature detection unit is configured so that the reversible thermosensitive recording medium is not in contact with the heating element. The temperature of the heating element is detected by detecting the voltage of the heating element, and the heating drive means can erase the image of the reversible thermosensitive recording medium based on the temperature of the heating element detected by the temperature detection means. Predicting a continuous heating drive time rising to a certain temperature range, and continuously driving and controlling the heating element until the reversible thermosensitive recording medium reaches a temperature range in which an image can be erased based on the predicted continuous heating drive time. It becomes possible to detect the temperature of the heating element at the time of startup or the like, and as a result, it is possible to accurately grasp the heating drive time required for warm-up.
[0094]
According to a thirteenth aspect of the present invention, in the image erasing apparatus according to any one of the first to twelfth aspects, the temperature detecting means sets the detected surface temperature of the reversible thermosensitive recording medium to a temperature at which the image can be erased. The heating driving means drives the heating element when the temperature detecting means determines that the surface temperature of the reversible thermosensitive recording medium has reached an image erasable temperature. If the surface temperature of the reversible thermosensitive recording medium is determined not to reach an image erasable temperature by the temperature detecting means, the surface temperature of the reversible thermosensitive recording medium reaches a temperature at which the image can be erased. As described above, since the heating element and the conveyance unit are driven and controlled, the image erasing error is such that the image erasing operation is performed in a state where the surface temperature of the reversible thermosensitive recording medium does not reach the temperature erasable range It is possible to prevent.
[0095]
According to a fourteenth aspect of the present invention, in the image erasing apparatus according to any one of the first to thirteenth aspects, the heating driving means has a surface temperature of the reversible thermosensitive recording medium detected by the temperature detecting means. Based on this, the temperature reduction due to the conveyance of the reversible thermosensitive recording medium is predicted, and the heating element is driven and controlled to suppress unnecessary heating, so that the applied power required for unnecessary heating drive can be reduced. it can.
[0096]
According to the invention of claim 15, in the image erasing apparatus according to any one of claims 1 to 14, the temperature detecting means detects a voltage of the heating element to detect a temperature of the heating element, By comparing the temperature of the heating element with a predetermined abnormal temperature to determine whether or not the heating element is in an abnormal temperature state, it is possible to detect that the heating element is in an abnormal temperature state As a result, it is possible to prevent the occurrence of an image erasure failure due to a foreign object that hinders normal image erasing operation between the heating element and the reversible thermosensitive recording medium, a disconnection of the heating element, and an accident due to an abnormal temperature rise of the heating element. can do.
[0097]
According to a sixteenth aspect of the present invention, in the image erasing apparatus according to the fifteenth aspect, when the temperature detecting unit determines that the heating element is in an abnormal temperature state, a warning for warning the abnormality of the heating element. By providing the means, it is possible to notify the user of the necessity of stopping the apparatus, the necessity of maintenance, and the like. For example, if the image erasing quality deteriorates at an abnormal level, a warning lamp or the like can be notified that the heating element is in an abnormal temperature state to warn the user of the necessity for maintenance.
[0098]
According to a seventeenth aspect of the present invention, in the image erasing apparatus according to the fifteenth or sixteenth aspect, when the heating driving unit determines that the heating element is in an abnormal temperature state by the temperature detecting unit, Since the driving of the heating element is stopped, the driving of the heating element in an abnormal temperature state is stopped, and an accident or the like can be prevented.
[0099]
According to an image forming apparatus of an invention of claim 18, a reversible thermosensitive material which is conveyed along a conveying path by the image erasing apparatus according to any one of claims 1 to 17 and a conveying unit provided in the image erasing apparatus. An image forming unit that performs an image forming operation on the recording medium is provided, so that the same effect as that of any one of claims 1 to 17 can be obtained.
[0100]
According to the nineteenth aspect of the present invention, in the image forming apparatus according to the eighteenth aspect, the heating element provided in the image erasing device is positioned on the upstream side of the conveyance path from the image forming unit. An image can be formed on the reversible thermosensitive recording medium by the image forming unit after the image erasing operation according to the above.
[0101]
According to the twentieth aspect of the present invention, in the image forming apparatus according to the twentieth or nineteenth aspect, since the image forming unit is a thermal head, an image is easily formed on a reversible thermosensitive recording medium with a simple configuration. be able to.
[Brief description of the drawings]
FIG. 1 is a front view schematically showing an internal structure of a printer as an image forming apparatus according to an embodiment of the present invention.
FIG. 2 is a plan view schematically showing a heating element provided in the printer.
FIG. 3 is a cross-sectional view showing the internal structure of a reversible thermosensitive recording paper.
FIG. 4 is a block diagram schematically showing an electrical connection of each unit included in the printer.
FIG. 5 is a plan view schematically showing electrical connection of heating elements provided in the printer.
FIG. 6 is a front view schematically showing a part of the internal structure of the printer.
FIG. 7 is a flowchart showing a flow of image erasure processing.
[Explanation of symbols]
1 Image forming device (printer)
2 Reversible recording media (reversible thermosensitive recording paper)
4 Transport route (paper transport route)
5 Transport section
7 Image forming section
9 Image erasing device
14 Heating element
18 Thermal head
22 Reversible thermosensitive recording layer
34 Heating drive means (heating drive circuit)
35 Temperature detection means (temperature detection circuit)
33 Switching means (switching circuit)

Claims

A transport unit that transports a reversible thermosensitive recording medium having a reversible thermosensitive recording layer whose state is reversibly changed by heat, along a transport path;
A heating element comprising a plurality of heating resistors provided at a position in contact with the reversible thermosensitive recording medium being transported by the transport unit, the electrical resistance value changing depending on temperature;
Heating driving means for driving and controlling the heating element so as to cause the heating element to perform an image erasing operation for heating the reversible thermosensitive recording medium conveyed by the conveying unit;
An image erasing apparatus comprising: a temperature detecting unit that detects a voltage of the heating element and detects a surface temperature of the reversible thermosensitive recording medium conveyed by the conveying unit.

The image erasing apparatus according to claim 1, wherein the heating element is divided into a plurality of blocks.

The image erasing apparatus according to claim 2, wherein the temperature detection unit detects a voltage of the heating element for each of a plurality of blocks.

4. The image erasing apparatus according to claim 2, wherein the heating driving unit drives and controls the heating element for each of a plurality of blocks.

The image erasing apparatus according to claim 4, wherein the heating driving unit sequentially drives and controls the heating element along a sequence of blocks for each of a plurality of blocks.

Comprising a support substrate for supporting the heating element;
The image erasing apparatus according to claim 4, wherein the heating driving unit drives and controls the heating element for each of a plurality of blocks based on variation in a heat storage effect of the support substrate.

Comprising a support substrate for supporting the heating element;
6. The image erasing apparatus according to claim 2, wherein the division width of the heating element is set based on variation in a heat storage effect of the support substrate.

The temperature detection means detects the voltage of the heating element of the block facing the non-printable area of the reversible thermosensitive recording medium conveyed by the conveyance section, and the surface of the non-printable area of the reversible thermosensitive recording medium Detect temperature
The heating drive means is arranged in the printable area of the reversible thermosensitive recording medium conveyed by the conveying section based on the surface temperature of the nonprintable area of the reversible thermosensitive recording medium detected by the temperature detecting means. The image erasing apparatus according to any one of claims 2 to 7, wherein the heating element of the opposing block is driven and controlled.

The image erasing apparatus according to claim 1, further comprising a switching unit that switches between the heating driving unit and the temperature detection unit at a predetermined timing.

The image erasing apparatus according to claim 9, wherein the switching unit switches between the heating driving unit and the temperature detecting unit so as to keep a heating temperature constant during an image erasing operation by the heating element.

The switching means causes the temperature detection means to execute when the upstream and downstream unprintable areas in the transport direction of the reversible thermosensitive recording medium pass through positions facing the heating element, and the reversible thermosensitive recording. When the printable area of the medium passes through a position facing the heating element, the heating drive unit is executed,
11. The heating unit drives and controls the heating element based on surface temperatures of upstream and downstream non-printable areas of the reversible thermosensitive recording medium detected by the temperature detection unit. Image erasing device.

The temperature detection means detects the temperature of the heating element by detecting the voltage of the heating element in a state where the reversible thermosensitive recording medium is not in contact with the heating element;
The heating driving means predicts a continuous heating driving time during which the reversible thermosensitive recording medium rises to an image erasable temperature range based on the temperature of the heating element detected by the temperature detecting means, and predicts continuous The image forming apparatus according to any one of claims 1 to 11, wherein the heating element is continuously driven and controlled until the reversible thermosensitive recording medium reaches an erasable temperature range based on a heating driving time.

The temperature detection means determines whether the detected surface temperature of the reversible thermosensitive recording medium has reached an image erasable temperature,
When the temperature detecting means determines that the surface temperature of the reversible thermosensitive recording medium has reached an image erasable temperature, the heating driving means does not drive the heating element, and the temperature detecting means When it is determined that the surface temperature of the reversible thermosensitive recording medium has not reached the temperature at which the image can be erased, the heating element and the transport unit are set so that the surface temperature of the reversible thermosensitive recording medium reaches the temperature at which the image can be erased. The image erasing apparatus according to claim 1, wherein the image erasing apparatus controls driving of the image erasing apparatus.

The heating drive means predicts a temperature drop due to transport of the reversible thermosensitive recording medium based on the surface temperature of the reversible thermosensitive recording medium detected by the temperature detecting means, and suppresses unnecessary heating. The image erasing apparatus according to claim 1, wherein the heating element is driven and controlled.

The temperature detecting means detects the temperature of the heating element by detecting the voltage of the heating element, and compares the temperature of the heating element with a predetermined abnormal temperature to determine whether or not the heating element is in an abnormal temperature state. 15. The image erasing apparatus according to claim 1, wherein the image erasing apparatus determines whether or not.

16. The image erasing apparatus according to claim 15, further comprising a warning unit that warns of an abnormality of the heating element when the temperature detecting unit determines that the heating element is in an abnormal temperature state.

17. The image erasing apparatus according to claim 15, wherein the heating driving unit stops driving the heating element when the temperature detection unit determines that the heating element is in an abnormal temperature state.

An image erasing apparatus according to any one of claims 1 to 17, and an image forming section that performs an image forming operation on a reversible thermosensitive recording medium transported along a transport path by a transport section included in the image erasing apparatus. ,
An image forming apparatus comprising:

The image forming apparatus according to claim 18, wherein the heating element included in the image erasing apparatus is positioned upstream of the image forming unit in the conveyance path.

The image forming apparatus according to claim 18, wherein the image forming unit is a thermal head.