JP3963697B2 - Thermal printer - Google Patents

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JP3963697B2
JP3963697B2 JP2001322491A JP2001322491A JP3963697B2 JP 3963697 B2 JP3963697 B2 JP 3963697B2 JP 2001322491 A JP2001322491 A JP 2001322491A JP 2001322491 A JP2001322491 A JP 2001322491A JP 3963697 B2 JP3963697 B2 JP 3963697B2
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platen
support member
bearing
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thermal printer
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JP2003127445A (en
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邦彦 舟田
博己 大塚
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Fujitsu Component Ltd
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Fujitsu Component Ltd
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Description

【０００１】
【発明の属する技術分野】
本発明は、サーマルプリンタに関する。
【０００２】
【従来の技術】
サーマルヘッドとプラテンとを有する感熱式印字部を備えたサーマルプリンタは、部品点数が比較的少なく小形化が容易であるため、キャッシュレジスター、携帯型端末装置、ＡＴＭ等の併設プリンタとして広く採用されている。この種のサーマルプリンタにおいて、ロール形態で装填される印刷用紙（すなわちロール紙）の補給／交換作業を容易にするために、互いに開閉動作可能に組み合わされる一対の支持部材にサーマルヘッドとプラテンとを個別に搭載して、開閉可能な印字部を構成したものが知られている。このような開閉可能な印字部を有するサーマルプリンタは、補給／交換した新たなロール紙を印字待機状態にセットする際に、両支持部材を開いてサーマルヘッドとプラテンとを互いに十分に離隔した状態で、例えばプラテンにロール紙の用紙前端部分を載せ、次いで両支持部材を閉じることにより、容易かつ迅速に用紙セットできる利点を有する。
【０００３】
上記した開閉可能な印字部を有するサーマルプリンタでは、印字部及び一対の支持部材を閉じている間、安定した印字作業を遂行できるように、サーマルヘッドとプラテンとを予め定めた相対的位置関係に保持することが要求される。特に、回転するプラテンに対し固定的に配置したサーマルヘッドの多数の発熱体を電気的に走査して印字を行うラインサーマルプリンタでは、サーマルヘッドとプラテンとの間に印字作業に要する所定の接触圧力を確保しなければならず、したがって上記した印字部開閉構造を有する場合、印字部及び一対の支持部材を閉じている間に、そのような接触圧力を維持しつつ印字部を閉位置すなわち作用位置に固定的に保持することが必要となっている。そこで、印字部開閉型のサーマルプリンタは一般に、印字作業の間、印字部及び一対の支持部材を閉位置に固定的かつ解除可能に係止するための係止機構を備えている。このような係止機構としては、揺動式フック等の専用の係合部材を用いるもの（例えば特開平５−１０４８１８号公報参照）や、サーマルヘッドとプラテンとの間の接触圧力を利用するもの（例えば特表平８−５０５５７６号公報参照）が知られている。
【０００４】
【発明が解決しようとする課題】
従来の印字部開閉型サーマルプリンタにおける上記した係止機構において、揺動式フック等の専用の係合部材を用いる場合には、部品点数の増加によりプリンタの全重量が増加したり、係合部材自体の耐久性及び作動信頼性を確保するために製造コストが上昇したりする危惧がある。またこの構成では、作業者が、係合部材による支持部材同士の係止作用を解除する手操作と、係止解除後に一対の支持部材を開く手操作とを段階的に（例えば両手を利用して）行う必要があり、ロール紙の補給／交換に時間を消費する課題がある。
【０００５】
特に、揺動式フックが、サーマルヘッドを支持する第１の支持部材に取り付けられて、第２の支持部材に回転自在に支持されたプラテンの軸部に解除可能に係合する係合部材として構成される場合は、揺動式フックとプラテン軸部との円滑な係合／離脱を可能にするために、揺動式フックに係留されている状態でプラテン軸部が第１支持部材に対して若干の遊びを有することが好ましい。しかし、このようなプラテン軸部の遊びは、印字作業中にサーマルヘッドとプラテンとの相対的位置ずれを引き起こして、印字品質に影響を及ぼす懸念を生じる。
【０００６】
さらにこの構成では、印字部を作用位置に保持している間に、サーマルヘッドからプラテンに負荷される接触圧力や、プラテン駆動源からプラテン軸部に負荷される剪断力が、プラテン軸部から揺動式フックに伝達されるので、揺動式フックは、その回動中心からプラテン係合点までの距離が大きい場合は特に、強化金属等の剛性材料から作製される必要がある。このような剛性材料の使用は、サーマルプリンタの重量や製造コストの増加の要因となり得る。
【０００７】
また、サーマルヘッドとプラテンとの間の接触圧力を利用して印字部を閉位置すなわち作用位置に解除可能に係止する構成では、プラテンが作用位置にある間、この接触圧力が印字部及び一対の支持部材を閉位置に保持する方向へ作用するように、サーマルヘッドとプラテンとが相対的に位置決めされるので、両支持部材を開放しようとする際に、この接触圧力に抗してサーマルヘッドとプラテンとを解離させなければならない。その結果、印刷用紙の補給／交換作業の都度、過剰な労力が消費されることになり、作業性の悪化やプリンタ構成部品の劣化促進が懸念される。
【０００８】
したがって本発明の目的は、開閉可能な印字部を有するサーマルプリンタにおいて、部品点数の増加、製造コストの上昇、用紙補給／交換作業性の悪化等の不都合を生じることなく、印字作業の間、一対の支持部材を閉じた状態に固定的に係止できるとともに、印字部のサーマルヘッドとプラテンとを作用位置に確実かつ安定的に保持できる新規で有用な係止機構を備え、以って安定した印字作業を遂行できる高性能のサーマルプリンタを提供することにある。
【０００９】
【課題を解決するための手段】
上記目的を達成するために、請求項１に記載の発明は、サーマルヘッドと、サーマルヘッドを支持する第１支持部材と、第１支持部材に相対移動可能に組み合わされる第２支持部材と、第２支持部材に支持され、第１支持部材に対する第２支持部材の移動に伴い、サーマルヘッドと協働して印刷用紙を挟持する作用位置とサーマルヘッドから離隔して印刷用紙を解放する非作用位置との間で変位するプラテンと、プラテンを作用位置に解除可能に係止する係止機構とを具備するサーマルプリンタにおいて、係止機構は、プラテンに回転軸線方向移動自在に連結される軸受部材と、軸受部材をプラテンに対し回転軸線方向へ弾性的に付勢する弾性部材と、第１支持部材に設けられ、プラテンが作用位置にあるときに、弾性部材の弾性的付勢力下で、軸受部材に脱離可能に係合して軸受部材を予め定めた位置に固定的に保持するとともに、軸受部材を介してプラテンを回転自在に作用位置に保持する保持部とを具備することを特徴とするサーマルプリンタを提供する。
【００１０】
請求項２に記載の発明は、請求項１に記載のサーマルプリンタにおいて、軸受部材は、回転軸線を中心とした錐体状輪郭を有する外輪部分を備え、保持部は、外輪部分の錐体状輪郭に適合する凹面輪郭を有する受容部分を備え、プラテンが作用位置にあるときに、受容部分が外輪部分を弾性的付勢力下で密接受容して静止保持するサーマルプリンタを提供する。
【００１１】
請求項３に記載の発明は、請求項１又は２に記載のサーマルプリンタにおいて、プラテンが、筒状本体と筒状本体の軸線方向両端面から軸線方向移動可能に同心状に突出する軸部とを備え、軸受部材は、軸部の少なくとも一方の突出部分に装着されて、弾性部材の弾性的付勢力を受けるサーマルプリンタを提供する。
【００１４】
請求項４に記載の発明は、サーマルヘッドと、サーマルヘッドを支持する第１支持部材と、第１支持部材に相対移動可能に組み合わされる第２支持部材と、第２支持部材に支持され、第１支持部材に対する第２支持部材の移動に伴い、サーマルヘッドと協働して印刷用紙を挟持する作用位置とサーマルヘッドから離隔して印刷用紙を解放する非作用位置との間で変位するプラテンと、プラテンを作用位置に解除可能に係止する係止機構とを具備するサーマルプリンタにおいて、係止機構は、プラテンの作用位置と非作用位置との間の移動軌跡に沿って第１支持部材に設けられ、プラテンが作用位置にあるときに、プラテンの軸部を回転自在に受容する軸受溝と、第２支持部材に移動可能に取着され、第１支持部材に係合して、プラテンの軸部を軸受溝内に係留する係合部材とを具備し、係合部材を第１支持部材から離脱させるために係合部材に加える力の方向が、係合部材が第１支持部材から離脱した後に、プラテンを作用位置から非作用位置へ移動させるために第２支持部材に加える力の方向と、実質的に同じであることを特徴とするサーマルプリンタを提供する。
【００１５】
請求項５に記載の発明は、サーマルヘッドと、サーマルヘッドを支持する第１支持部材と、第１支持部材に相対移動可能に組み合わされる第２支持部材と、第２支持部材に支持され、第１支持部材に対する第２支持部材の移動に伴い、サーマルヘッドと協働して印刷用紙を挟持する作用位置とサーマルヘッドから離隔して印刷用紙を解放する非作用位置との間で変位するプラテンと、プラテンを作用位置に解除可能に係止する係止機構とを具備するサーマルプリンタにおいて、係止機構は、プラテンの作用位置と非作用位置との間の移動軌跡に沿って第１支持部材に設けられ、プラテンが作用位置にあるときに、プラテンの軸部を回転自在に受容する軸受溝と、第１支持部材に回動可能に取着され、作用位置にあるプラテンにその回転を許容しつつ係合して、プラテンの軸部を軸受溝内に係留する係合部材とを具備し、係合部材は、第１支持部材上に位置する回動中心と、プラテン回転軸線方向に見て軸受溝の内側に突出可能な縁部とを有し、係合部材の縁部は、作用位置にあるプラテンにプラテン回転軸線方向に見て軸受溝の内側で係合する係合点を有するとともに、係合点に隣接して、係合部材の回動中心からの距離が係合点よりも大きくなる係止領域を有し、回動中心、係合点及び係止領域が、プラテンを作用位置に固定的に保持するような相対位置関係を有することを特徴とするサーマルプリンタを提供する。
【００１６】
請求項６に記載の発明は、請求項５に記載のサーマルプリンタにおいて、係合部材を、縁部がプラテン回転軸線方向に見て軸受溝の内側に突出する方向へ弾性的に付勢する弾性部材をさらに具備するサーマルプリンタを提供する。
【００１７】
請求項７に記載の発明は、請求項１〜６のいずれか１項に記載のサーマルプリンタにおいて、プラテンを回転駆動する駆動機構が第１支持部材に設置され、プラテンが作用位置にあるときにプラテンが駆動機構に作用的に連結されるとともに、プラテンが非作用位置にあるときにプラテンが駆動機構から分離されるサーマルプリンタを提供する。
【００１８】
請求項８に記載の発明は、請求項１〜７のいずれか１項に記載のサーマルプリンタにおいて、第２支持部材が第１支持部材に相対回動可能に組み合わされ、第１支持部材に対する第２支持部材の回動に伴い、プラテンが作用位置と非作用位置との間で変位するサーマルプリンタを提供する。
【００１９】
【発明の実施の形態】
以下、添付図面を参照して、本発明の実施の形態を詳細に説明する。全ての図面に渡って、同一又は類似の構成要素には共通の参照符号を付す。
図１は、開閉可能な印字部を有する本発明の一実施形態によるサーマルプリンタ１０の、印字部開放時の概略斜視図、図２は、サーマルプリンタ１０の係止機構の構成を概略で示す部分断面正面図、図３は、係止機構の動作説明図である。
【００２０】
サーマルプリンタ１０は、サーマルヘッド１２と、サーマルヘッド１２を支持する第１支持部材１４と、第１支持部材１４に相対移動可能に組み合わされる第２支持部材１６と、第２支持部材１６に支持され、第１支持部材１４に対する第２支持部材１６の移動に伴いサーマルヘッド１２に対して移動するプラテン１８とを備える。図示実施形態によるサーマルプリンタ１０は、主として携帯型端末装置に併設かつ連結して使用できる形態を有するが、本発明に係るサーマルプリンタの用途は限定されない。
【００２１】
第１支持部材１４は、平坦部分及び湾曲部分を有する底壁２０と、底壁２０の両側縁に沿って直立状に延設される平坦な両側壁２２とを一体に備える。底壁２０の平坦部分とそれに隣接する両側壁２２の一部分とは、サーマルヘッド１２及びプラテン駆動機構（後述する）を搭載する主領域２４を、第１支持部材１４上に画定する。また、底壁２０の湾曲部分とそれに隣接する両側壁２２の他部分とは、ロール形態に巻かれたウエブ状に連続する印刷用紙Ｐ（すなわちロール紙Ｒ）を少なくとも部分的に収容する副領域２６を、主領域２４に隣接して第１支持部材１４上に画定する。
【００２２】
第２支持部材１６は、平坦部分及び湾曲部分を有する頂壁２８と、頂壁２８の両側縁に沿って直立状に延設される平坦な両側壁３０とを一体に備える。頂壁２８の平坦部分とそれに隣接する両側壁３０の一部分とは、プラテン１８を搭載する主領域３２を、第２支持部材１６上に画定する。また、頂壁２８の湾曲部分とそれに隣接する両側壁３０の他部分とは、ロール紙Ｒを少なくとも部分的に包囲する副領域３４を、主領域３２に隣接して第２支持部材１６上に画定する。
【００２３】
第１支持部材１４と第２支持部材１６とは、それぞれの主領域２４、３２から離れた側の副領域２６、３４の端部近傍で、共通の軸３６を介して相対回動自在に相互連結される。それにより、第１支持部材１４と第２支持部材１６とは、両者の主領域２４、３２及び副領域２６、３４を開閉する開閉動作を回動式に遂行でき、それに伴い、サーマルヘッド１２とプラテン１８とから構成される印字部が開閉動作できる。
【００２４】
サーマルヘッド１２は、所定位置に発熱体を配置した略平坦な印字面を有する平板状部材であり、第１支持部材１４の主領域２４上で印字面を副領域２６側に向けて、弾性体（例えば図示の板ばね）３８を介して第１支持部材１４上に受動変位可能に支持される。サーマルヘッド１２は、例えばその印字面に整列配置した多数の発熱体を電気的に走査して印字を行うラインドット構造を有することができる。弾性体３８は、外力により撓んでサーマルヘッド１２に副領域２６に接近する方向への弾性的付勢力を負荷するように構成され、それにより、プラテン１８が後述する作用位置にあるときに、サーマルヘッド１２とプラテン１８との間に印字作業に必要な所定の接触圧力を生成する。
【００２５】
プラテン１８は、好ましくはゴム等の弾性体からなる円筒状の本体３９と、本体３９の中心軸線に沿って固定される軸部４０とを備え、軸部４０により、第２支持部材１６の主領域３２に回転自在に架設される。プラテン１８は、ロール紙Ｒから繰り出された印刷用紙Ｐを、サーマルヘッド１２とプラテン１８との間に圧力下で挟持して、印刷用紙Ｐへの安定的な印字を実現するための背面支持ローラとして機能すると同時に、印刷用紙Ｐを摩擦力により連続的に送り出すための駆動ローラとして機能する。軸部４０は、プラテン１８の軸線方向両端面から軸線方向へ突出して、第２支持部材１６の主領域３２を構成する両側壁３２の対応部分に貫通形成した支承穴４２に、回転自在に遊挿される。
【００２６】
プラテン１８は、第１支持部材１４に対する第２支持部材１６の回動に伴い、サーマルヘッド１２と協働して印刷用紙Ｐを挟持する作用位置（図示せず）と、サーマルヘッド１２から離隔して印刷用紙Ｐを解放する非作用位置（図１）との間で、軸３６を中心として所望角度に渡る円弧状の軌跡に沿って変位（すなわち公転動作）する。なお、プラテン１８が作用位置にある間は、プラテン１８すなわち軸部４０の回転軸線は、第１及び第２支持部材１４、１６を相互連結する軸３６の軸線に実質的平行に配置される。
【００２７】
プラテン１８の軸部４０には、第２支持部材１６の両側壁３０から外方へ突出する部分４０ａに、それぞれ軸受部材４４が装着される。他方、第１支持部材１４の両側壁２２には、主領域２４と副領域２６との境界領域に、プラテン１８の変位（公転）軌跡に沿って延びる軸受溝４６が、両側壁２２の上端から所定長さに渡ってそれぞれ形成される。さらに、第１支持部材１４の両側壁２２には、それらの相互対向面に、それぞれの軸受溝４６に隣接して受容部分４８が凹設される。プラテン１８が作用位置にあるときに、軸部４０の両突出部分４０ａは対応の軸受溝４６に隙間を介して受容され、両軸受部材４４が後述するように対応の受容部分４８に嵌入される。それによりプラテン１８は、一対の軸受部材４４を介して、第１支持部材１４に回転自在に支持される。
【００２８】
プラテン１８の軸部４０にはさらに、第２支持部材１６の一方の側壁３０から外方へ突出する突出部分４０ａの先端に、従動輪５０が固定される。他方、第１支持部材１４の主領域２４には、プラテン１８を回転駆動するための駆動機構として、動力伝達機構５２（例えば歯車列）及び駆動源５４（例えば電動機）が設置される。プラテン１８が作用位置にあるときに、従動輪５０は動力伝達機構５２に係合するとともに、動力伝達機構５２を介して駆動源５４に作用的に連結される。それにより、駆動源５４のトルクが軸部４０に伝達されて、プラテン１８が回転する。また、プラテン１８が作用位置から非作用位置へ変位するに伴い、従動輪５０は動力伝達機構５２から脱離し、それによりプラテン１８が駆動源５４から分離される。なお、サーマルヘッド１２及び駆動源５４は、第１支持部材１４の主領域２４に隣接して配置可能な制御回路板（図示せず）及びバッテリー（図示せず）に接続できる。
【００２９】
サーマルプリンタ１０においては、プラテン１８が作用位置にある間、安定した印字作業を遂行できるように、サーマルヘッド１２とプラテン１８との間に印字作業に要する所定の接触圧力を維持しつつ、第１及び第２支持部材１４、１６を閉位置に固定的に保持する必要がある。その目的でサーマルプリンタ１０は、印字作業の間、プラテン１８を作用位置に解除可能に係止する係止機構を備えている。
【００３０】
図示実施形態では、係止機構は、プラテン１８に回転軸線方向移動自在に連結される上記した一対の軸受部材４４と、それら軸受部材４４をプラテン１８に対し回転軸線方向へ弾性的に付勢する一対の弾性部材５６と、第１支持部材１４に設けられ、プラテン１８が作用位置にあるときに、両弾性部材５６の弾性的付勢力下で、両軸受部材４４に脱離可能に係合してそれら軸受部材４４を予め定めた位置に固定的に保持する保持部、すなわち上記した一対の受容部分４８とから構成される。
【００３１】
詳述すれば、図２に示すように、プラテン１８の軸部４０は、プラテン１８の本体３９を回転軸線１８ａに沿って貫通して本体３９に固定されるコア部分４０ｂと、コア部分４０ｂよりも小径で、コア部分４０ｂの軸線方向両端面から同心状に軸線方向へ突出する前述した一対の突出部分４０ａとを、互いに一体に連結して備える。それら突出部分４０ａとコア部分４０ｂとの間には、環状の肩面４０ｃがそれぞれ形成される。各突出部分４０ａには、前述した軸受部材４４の内輪部分（図示せず）が、スプライン等の周知の連結要素（図示せず）を介して、回転不能かつ所定範囲に渡り回転軸線方向移動可能に連結される。
【００３２】
一対の軸受部材４４の各々は、プラテン１８の回転軸線１８ａを中心とした錐体（図では円錐台）状輪郭を有する外輪部分４４ａを備える。外輪部分４４ａは、内輪部分に対し、ラジアル負荷及びスラスト負荷に抗しつつ回転自在であり、したがって軸部４０に対し、回転軸線１８ａを中心に回転自在かつ所定範囲に渡り軸線方向移動可能となっている。各外輪部分４４ａは、その小径端面を軸部４０の各突出部分４０ａの先端側に向けて配置される。
【００３３】
一対の弾性部材５６の各々は、軸部４０の各環状肩面４０ｃとそれに対向する各軸受部材４４の内輪部分との間に、軸線方向へ弾性的圧縮可能に設置される。好ましくは各弾性部材５６は、軸部４０の突出部分４０ａ上で軸受部材４４が軸線方向移動範囲の外側限界位置にあるときに、軸部４０の環状肩面４０ｃと軸受部材４４の内輪部分との間に初期圧縮状態で挟持される。したがって各軸受部材４４は、対応の弾性部材５６の弾性的付勢力に抗して、対応の突出部分４０ａ上で軸線方向移動範囲の外側限界位置から内側限界位置まで移動できる。なお、弾性部材５６としては、図示のような圧縮コイルばねを有利に使用できる。
【００３４】
第１支持部材１４の一対の受容部分４８は、軸受部材４４の外輪部分４４ａの錐体状輪郭に適合する凹面輪郭をそれぞれに有する。したがって、各受容部分４８はその凹状表面で、軸受部材４４の外輪部分４４ａのテーパ状表面に密接可能となっている。なお、上記した一対の軸受部材４４がいずれも軸線方向移動範囲の外側限界位置にあるとき（すなわち両弾性部材５６が初期圧縮状態にあるとき）に、それら軸受部材４４の外輪部分４４ａにおける小径端面同士の間隔は、第１支持部材１４の両側壁２２同士の間隔よりも大きく、かつ外輪部分４４ａの大径端面同士の間隔は、第１支持部材１４の両側壁２２同士の間隔よりも小さくなるように、各構成部分の寸法が設定される。
【００３５】
上記構成を有する係止機構の作用を、図２及び図３を参照して説明する。
第２支持部材１６を第１支持部材１４に対し軸３６を中心に回動させて、プラテン１８を図１の非作用位置から作用位置に向けて移動させると、プラテン１８の軸部４０の両突出部分４０ａは、第１支持部材１４の両側壁２２の軸受溝４６に接近する（図２矢印Ａ）。第２支持部材１６が所定の回動位置に到達すると、両軸受部材４４がそれらの外輪部分４４ａのテーパ状表面にて、対応の軸受溝４６の上端開口を規定する両側壁２２の縁部にそれぞれ衝突する（図３（ａ））。
【００３６】
この状態から、第２支持部材１６を第１支持部材１４にさらに接近する方向へ押圧すると、両軸受部材４４の外輪部分４４ａがそのテーパ状表面にて対応の軸受溝４６の縁部に沿って摺動する。このとき、外輪部分４４ａのテーパ状表面が軸受溝４６の縁部から受ける反作用の軸線方向分力により、各軸受部材４４は、対応の弾性部材５６を弾性的に圧縮しつつ、プラテン１８の本体３９に接近する方向へ軸部４０の各突出部分４０ａ上で移動する（図３（ｂ）矢印Ｂ）。両軸受部材４４が、それらの外輪部分４４ａにおける小径端面同士の間隔が第１支持部材１４の両側壁２２同士の間隔に実質的に等しくなるまで移動すると、両軸受部材４４が両側壁２２の間に挿入され、各突出部分４０ａが各軸受溝４６に受容される（図３（ｂ））。
【００３７】
この状態からさらに、第２支持部材１６を第１支持部材１４に接近する方向へ押圧すると、両軸受部材４４の外輪部分４４ａがそれらの小径端面で第１支持部材１４の両側壁２２の内面上を摺動する。その後、軸受部材４４の小径端面の全体が対応の受容部分４８に進入すると、対応の弾性部材５６の弾性的付勢力によって、外輪部分４４ａのテーパ状表面が対応の受容部分４８の凹状表面に沿って摺動しつつ、各軸受部材４４が略自動的に、プラテン１８の本体３９から離れる方向へ軸部４０の各突出部分４０ａ上で移動する（図３（ｃ）矢印Ｃ）。そして最終的に、両軸受部材４４の外輪部分４４ａは、それらのテーパ状表面が対応の受容部分４８の凹状表面に全体的に密接した状態で、実質的同時に両受容部分４８に受容されて、所定位置に静止保持される。この状態で、プラテン１８は、一対の軸受部材４４と対応の受容部分との協働により、第１支持部材１４に回転自在に支持されるとともに、作用位置に固定的に保持される（図３（ｃ））。
【００３８】
なお、プラテン１８の軸部４０に装着された一対の軸受部材４４が第１支持部材１４に設けた対応の受容部分４８に受容されている間は、弾性部材５６の弾性的付勢力が両軸受部材４４に負荷されていることが有利である。この構成によれば、両軸受部材４４の外輪部分４４ａは、それらのテーパ状表面が対応の受容部分４８の凹状表面に弾性部材５６の弾性的付勢力下で密着して、強固に静止保持される。その結果、印字作業の間、サーマルヘッド１２とプラテン１４とが作用位置に確実かつ安定的に保持されるようになり、安定した印字作業を遂行できるようになる。
【００３９】
プラテン１８を非作用位置から作用位置へ移動させる場合は、図３（ｃ）の状態から、第２支持部材１６を第１支持部材１４から引き離す方向へ操作する。それにより、両軸受部材４４の外輪部分４４ａのテーパ状表面に、対応の受容部分４８の凹状表面から圧力が負荷され、その圧力の軸線方向分力により、各軸受部材４４は、対応の弾性部材５６を弾性的に圧縮しつつ、プラテン１８の本体３９に接近する方向へ軸部４０の各突出部分４０ａ上で移動する。そして、両軸受部材４４の外輪部分４４ａが対応の受容部分４８から脱離した後、図３（ｂ）に示す状態を経て、両軸受部材４４が第１支持部材１４から離脱する。その後、継続して第２支持部材１６を開位置へ向けて回動させることにより、プラテン１８を非作用位置へ変位させることができる。
【００４０】
上記構成を有するサーマルプリンタ１０によれば、プラテン１８を第１支持部材１４に回転自在に装着するために本来必要とされる軸受部材４４を利用して、印字作業の間、第１及び第２支持部材１４、１６を閉位置に固定的に係止する構成としたから、従来のサーマルプリンタにおける揺動式フック等の専用の係合部材の使用を回避でき、したがって部品点数及びプリンタ全重量の増加や製造コストの上昇が防止される。しかも、軸受部材４４と受容部分４８との協働により、印字作業の間、印字部（サーマルヘッド１２及びプラテン１８）を作用位置に確実に固定的に係止できるので、安定した印字作業を遂行できる。また、作業者が、軸受部材４４と受容部分４８との協働による第１及び第２支持部材１４、１６間の係止作用を解除する手操作と、係止解除後にそれら支持部材１４、１６を開く手操作とを、区別することなく一連の動作で実施できるので、ロール紙Ｒを容易かつ迅速に補給／交換することができる。
【００４１】
さらに、第１及び第２支持部材１４、１６を開閉動作（すなわち係止機構を係脱動作）させる際に必要な操作力は、一対の弾性部材５６のばね力を調整することにより、容易に設定かつ変更できる。この操作力は、サーマルヘッド１２とプラテン１８との間に要求される接触圧力とは無関係に設定できる。また、軸受部材４４の外輪部分４４ａのテーパ状表面と受容部分４８の凹状表面との接触面積を比較的大きく取れるので、開閉動作を繰り返したときの両接触表面の摩耗を低減することができる。
【００４２】
上記実施形態によるサーマルプリンタ１０は、様々な変形及び修正を行うことができる。例えば、弾性部材５６によって軸線方向へ付勢される軸受部材４４は、プラテン１８の軸部４０の少なくとも一方の突出部分４０ａに設置されればよい。この場合、軸受部材４４を設置しない側の軸部４０の突出部分４０ａには、軸線方向へ移動不能な一般的な軸受部材を設置することができる。
【００４３】
また、前述した円錐台状の輪郭を有する軸受部材４４の外輪部分４４ａの代わりに、図４に示すような紡錘状に膨出した外周面を含む錐体状輪郭の外輪部分４４ｂを採用することもできる。この場合、第１支持部材１４には、外輪部分４４ｂの紡錘状外周面に適合する凹状表面を有する受容部分４８´を形成することができる。このような構成によれば、相互接触面積の増加により、軸受部材４４の外輪部分４４ｂを受容部分４８´に一層強固に静止保持することができる。
【００４４】
また、弾性部材５６として、前述した円筒状の圧縮コイルばねの代わりに、図５（ａ）に示すような円錐状の圧縮コイルばねを採用することもできる。この構成によれば、弾性部材５６を最大に圧縮したときの軸受部材４４と軸部４０の肩面４０ｃとの間隔Ｓ（図５（ｂ））を、円筒状圧縮コイルばねを用いた構造に比べて縮小できるので、プラテン１８の軸線方向寸法及びサーマルプリンタ１０の幅方向寸法を一層削減することができる。
【００４５】
また、図６に示すように、プラテン１８の軸部４０に装着される一対の軸受部材４４を、それぞれの外輪部分４４ａの小径端面がプラテン１８の本体３９に対向するように方向付けして、両突出部分４０ａに配置することもできる。この場合、一対の弾性部材５６は、一方の突出部分４０ａにおいてはその先端に固定した従動輪５０と軸受部材４４との間に設置され、他方の突出部分４０ａにおいてはその先端に固定したストッパ５８と軸受部材４４との間に設置される。また、軸受部材４４の外輪部分４４ａを受容する受容部分４８は、第１支持部材１４の両側壁２２の外面に形成される。
【００４６】
さらに、図７に示すように、プラテン１８の軸部４０を、軸線方向両端に中空領域６０ａを有する円筒状のコア部分６０と、コア部分６０のそれら中空領域６０ａに部分的に収容される一対の突出部分６２とから構成することもできる。この場合、各突出部分６２は、スプライン等の周知の連結要素（図示せず）を介して、回転不能かつ所定範囲に渡り回転軸線方向移動可能に、コア部分６０に連結される。また、弾性部材５６は、コア部分６０の各中空領域６０ａに収容されて、対応の突出部分６２を軸線方向外方へ弾性的に付勢する。この構成によれば、弾性部材５６を最大に圧縮したときの軸受部材４４と軸部４０の肩面（コア部分６０の端面６０ｂ）との間隔を、実質的に排除できるので、プラテン１８の軸線方向寸法及びサーマルプリンタ１０の幅方向寸法を一層削減することができる。
【００４７】
図８〜図１１は、印字作業の間、印字部（サーマルヘッド１２及びプラテン１８）を作用位置に解除可能に係止する係止機構として、揺動式フックの形態を有する係合部材を採用した本発明の第２の実施形態によるサーマルプリンタの、係止機構の幾つかの具体的構成を概略的に示す。なお、これらの図面に示す各種係止機構は、第１の実施形態によるサーマルプリンタ１０に、軸受部材４４、受容部分４８及び弾性部材５６からなる前述した係止機構の代わりに搭載できるものである。したがって、サーマルプリンタ１０と共通する構成要素は、同一の符号を付してその説明を省略する。
【００４８】
図８に示す係止機構は、プラテン１８の作用位置と非作用位置との間の移動軌跡に沿って第１支持部材１４に設けられ、プラテン１８が作用位置にあるときに、プラテン１８の軸部４０を回転自在に受容する軸受溝４６と、第１支持部材１４に移動可能に取着され、作用位置にあるプラテン１８にその回転を許容しつつ係合して、プラテン１８の軸部４０を軸受溝４６内に係留する係合部材６４と、作用位置にあるプラテン１８を係合部材６４に弾性的に押し付けて、係合部材６４との協働によりプラテン１８を作用位置に固定的に保持する弾性部材６６とを備えて構成される。
【００４９】
詳述すれば、係合部材６４は、Ｌ字状に延びる腕部分６４ａと、腕部分６４ａの一端領域で側方へ突設されるフック部分６４ｂとを一体に備える。係合部材６４は、フック部分６４ｂから離れた腕部分６４ａの他端領域にて、軸６８を介して第１支持部材１４の一方の側壁２２に取り付けられる。それにより係合部材６４は、第１支持部材１４の側壁２２の表面（例えば外面）に沿って、軸６８を中心に回動自在になっている。ここで、係合部材６４の各部寸法及び形状並びに係合部材６４上での軸６８の位置は、係合部材６４の回動中、フック部分６４ｂが第１支持部材１４の軸受溝４６に重畳する位置を通過するように設定される。
【００５０】
プラテン１８が非作用位置から作用位置へ移動する間に、プラテン１８の軸部４０は、その両端の突出部分４０ａが対応の軸受溝４６に遊挿される。軸部４０の突出部分４０ａが軸受溝４６の底縁に隣接する位置まで挿入された時点で、プラテン１８が作用位置に到達する。図示のように、係合部材６４のフック部分６４ｂが軸受溝４６に重畳する位置にあるときに、フック部分６４ｂの内縁（すなわち軸６８に近い側の縁部）と軸受溝４６の底縁とは、それらの間に軸部４０の突出部分４０ａを僅かな隙間を介して受容可能な距離だけ互いに離れて配置される。したがって、プラテン１８が作用位置にあるときに、係合部材６４をそのフック部分６４ｂが軸受溝４６に重畳する位置に配置すると、軸部４０の突出部分４０ａは、フック部分６４ｂの内縁と軸受溝４６の底縁との間に、僅かな隙間を介して受容される。
【００５１】
弾性部材６６は、軸受溝４６に受容された軸部４０の突出部分４０ａを、軸受溝４６に沿って軸受溝４６から押し出す方向へ作用する弾性的付勢力を、軸部４０に負荷する。したがって、プラテン１８が作用位置にあるときに、係合部材６４をそのフック部分６４ｂが軸受溝４６に重畳する位置に配置すると、軸部４０の突出部分４０ａは、軸受溝４６の底縁の近傍で弾性部材６６の弾性的付勢力を受けて、フック部分６４ｂの内縁に圧力下で当接される。その状態で、軸部４０の突出部分４０ａは、係合部材６４と弾性部材６６との協働により軸受溝４６内に固定的に係留され、それによりプラテン１８が作用位置に固定的に保持される。この状態から、係合部材６４を回動させて軸部４０の突出部分４０ａから離脱させると、軸部４０の突出部分４０ａが弾性部材６６の付勢力により、軸受溝４６の底縁から離れるように押し上げられる。それによりプラテン１８は、作用位置から移動する。
【００５２】
なお、好ましくは係合部材６４は、図示しないばね等の付勢手段により、フック部分６４ｂが軸部４０の突出部分４０ａを軸受溝４６内に係留する位置に向けて、弾性的に付勢される。この構成によれば、プラテン１８を作用位置に配置する際に、軸部４０の突出部分４０ａを軸受溝４６に挿入する動作に応じて、係合部材６４が付勢手段の弾性的付勢力下で自動的に回動してフック部分６４ｂが突出部分４０ａに係合し、突出部分４０ａを軸受溝４６内に係留する。
【００５３】
上記した係止機構を操作する際に、作業者は、係合部材６４による印字部係止作用を解除する手操作と、係止解除後に印字部を開く手操作とを、片手で連続的に行うことができる。この係止解除操作を説明すると、作業者はまず係合部材６４を、図８に示す係留位置から、係合部材６４のフック部分６４ｂの近傍に延設した操作部分６４ｃを片手で操作して、軸６８を中心に図で反時計方向へ回転させる。それにより、プラテン１８の軸部４０の突出部分４０ａが係合部材６４から離脱して、弾性部材６６の付勢力により、軸受溝４６の底縁から離れるように押し上げられる。それに伴い、プラテン１８は作用位置から移動する。
【００５４】
プラテン１８が作用位置から移動する間、サーマルヘッド１２（図１）からプラテン１８に負荷される接触圧力により、軸部４０の突出部分４０ａは軸受溝４６の側縁に押し付けられる。したがって、弾性部材６６から軸部４０に負荷される弾性的付勢力が、サーマルヘッド１２とプラテン１８との間、及び軸部４０の突出部分４０ａと軸受溝４６の側縁との間に生じる摩擦力よりも低くなった時点で、軸受溝４６内での突出部分４０ａの移動が停止し、プラテン１８がその中間位置に静止する。この状態では、軸受溝４６内にある突出部分４０ａに係合部材６４のフック部分６４ｂが干渉するので、係合部材６４は突出部分４０ａをもはや係留することができない。そこで作業者は、係合部材６４の操作部分６４ｃから手を離し、同じ手で第２支持部材１６（図１）を操作して、軸部４０の突出部分４０ａを軸受溝４６から完全に脱離した後、プラテン１８を非作用位置へ移動させることができる。
【００５５】
このように、上記した係止機構を有するサーマルプリンタでは、作業者が、係合部材６４によるプラテン軸部４０の係留作用を解除する手操作と、係留解除後にプラテン１８を非作用位置へ移動させる手操作とを、片手で連続的に実施できるので、ロール紙Ｒ（図１）を容易かつ迅速に補給／交換することができる。なお、上記した係止機構は、プラテン軸部４０の両端の突出部分４０ａに関連して、第１支持部材１４の両側壁２２のそれぞれに設置することもできる。
【００５６】
弾性部材６６は、図８に示す圧縮コイルばねの他に、図９に示すねじりコイルばね等の、様々な弾性要素から構成することができる。また、図１０に示すように、サーマルプリンタに、印字部が作用位置にあることを検出するためのスイッチ機構７０を設け、プラテン軸部４０がスイッチ機構７０の作動部材７２を動作させる構成とした場合は、作動部材７２に復旧ばね７４を装備することにより、この復旧ばね７４が弾性部材６６と同等の機能を果すように構成できる。この構成では、独立した弾性部材６６を省略できる。
【００５７】
上記した係止機構においては、係合部材６４のフック部分６４ｂとプラテン軸部４０の突出部分４０ａとの円滑な係合／離脱を可能にするために、フック部分６４ｂに係留されている状態で、軸部４０の突出部分４０ａが軸受溝４６に対して若干の遊びを有することが好ましい。特に図１１に示すように、突出部分４０ａに対する係合部材６４の係留保持力を高めるために、フック部分６４ｂが鋭角の先端を有する場合は、フック部分６４ｂと突出部分４０ａとの接点Ｐが、軸受溝４６内での突出部分４０ａの頂点部位よりも低い位置に配置されるので、係合部材６４の回動中に突出部分４０ａが軸受溝４６内で移動できるだけの遊びＧを設けることが不可欠になる。この場合にも、上記した係止機構の構成によれば、弾性部材６６が軸部４０の突出部分４０ａをフック部分６４ｂに弾性的に押し付けるので、プラテン１８は作用位置に安定的に保持され、印字品質に及ぼす影響が排除される。
【００５８】
図１２は、印字部を作用位置に解除可能に係止する係止機構として、揺動式フックの形態を有する係合部材を採用した本発明の第３の実施形態によるサーマルプリンタの、係止機構の構成を概略的に示す。なお、この係止機構は、第１の実施形態によるサーマルプリンタ１０に、軸受部材４４、受容部分４８及び弾性部材５６からなる前述した係止機構の代わりに搭載できるものである。したがって、サーマルプリンタ１０と共通する構成要素は、同一の符号を付してその説明を省略する。
【００５９】
この係止機構は、プラテン１８の作用位置と非作用位置との間の移動軌跡に沿って第１支持部材１４に設けられ、プラテン１８が作用位置にあるときに、プラテン１８の軸部４０を回転自在に受容する軸受溝４６と、第２支持部材１６に移動可能に取着され、第１支持部材１６に係合して、プラテン１８の軸部４０を軸受溝４６内に係留する係合部材７６とを備えて構成される。
【００６０】
詳述すれば、係合部材７６は、取付部分７６ａと、取付部分７６ａからＬ字状に延設されるフック部分７６ｂと、フック部分７６ｂの反対側で取付部分７６ａから延設される操作部分７６ｃとを一体に備える。係合部材７６は、取付部分７６ａにて、プラテン１８の軸部４０の突出部分４０ａに回転自在に取り付けられる。プラテン１８の軸部４０はまた、第２支持部材１６の自由端側に設けた一対のフレーム部分１６ａに回転自在に支持される。それにより係合部材７６は、第２支持部材１６の一方のフレーム部分１６ａの表面に沿って、プラテン軸部４０の突出部分４０ａを中心に回動自在になっている。
【００６１】
プラテン１８が非作用位置から作用位置へ移動する間に、プラテン１８の軸部４０は、その両端の突出部分４０ａが対応の軸受溝４６に遊挿される。軸部４０の突出部分４０ａが軸受溝４６の底縁に隣接する位置まで挿入された時点で、プラテン１８が作用位置に到達する。第１支持部材１４の一方の側壁２２には、プラテン１８が作用位置にあるときに、係合部材７６のフック部分７６ｂが係合可能な位置に、係止ピン７８が突設される。
【００６２】
図示のように、係合部材７６と第２支持部材１６との間には、プラテン１８が作用位置にあるときに、フック部分７６ｂが係止ピン７８に係合する方向へ、軸部４０の突出部分４０ａを中心として係合部材７６を回転付勢する弾性部材８０を設置することが好ましい。この構成によれば、プラテン１８を作用位置に配置する際に、軸部４０の突出部分４０ａを軸受溝４６に挿入する動作に応じて、係合部材７６が弾性部材８０の弾性的付勢力下で自動的に回動してフック部分７６ｂが係止ピン７８に係合し、それにより突出部分４０ａを軸受溝４６内に係留する。
【００６３】
上記した係止機構を操作する際に、作業者は、係合部材７６による印字部係止作用を解除する手操作と、係止解除後に印字部を開く手操作とを、片手で連続的に行うことができる。この係止解除操作を説明すると、作業者はまず係合部材７６を、図１２に示す係留位置から、操作部分７６ｃを片手で操作して、プラテン１８の軸部４０を中心に図で反時計方向へ回転させる。それにより、係合部材７６のフック部分７６ｂが係止ピン７８から離脱する。そこで作業者は、係合部材７６の操作部分７６ｃから手を離すことなく、そのまま同じ手で第２支持部材１６を操作して、軸部４０の突出部分４０ａを軸受溝４６から完全に脱離した後、プラテン１８を非作用位置へ移動させることができる。
【００６４】
このように、上記した係止機構を有するサーマルプリンタでは、係合部材７６を第１支持部材１４から離脱させるために係合部材７６に加える力の方向が、係合部材７６が第１支持部材１４から離脱した後に、プラテン１８を作用位置から非作用位置へ移動させるために第２支持部材１６に加える力の方向と、実質的に同じである。したがって作業者は、係合部材７６によるプラテン軸部４０の係留作用を解除する手操作と、係留解除後にプラテン１８を非作用位置へ移動させる手操作とを、片手で連続的に実施できるので、ロール紙Ｒ（図１）を容易かつ迅速に補給／交換することができる。なお、上記した係止機構は、プラテン軸部４０の両端の突出部分４０ａに関連して、第２支持部材１６の一対のフレーム部分１６ａのそれぞれに設置することもできる。
【００６５】
上記した揺動式フックの形態を有する係合部材６４、７６は、プラテン１８を作用位置に保持している間に、サーマルヘッド１２からプラテン１８に負荷される接触圧力や、動力伝達機構５２（図１）からプラテン軸部４０に負荷される剪断力を、プラテン軸部４０から受けるので、強化金属等の剛性材料から作製される必要がある。このような剛性材料の使用は、サーマルプリンタの重量や製造コストの増加の要因となり得る。図１３は、このような課題を解決できる新規な係合部材を採用した本発明の第４の実施形態によるサーマルプリンタ９０を概略的に示す。なお、サーマルプリンタ９０は、係止機構の構成以外は、第１の実施形態によるサーマルプリンタ１０と実質的同一の構成を有するので、両者に共通する構成要素は、同一の符号を付してその説明を省略する。
【００６６】
サーマルプリンタ９０は、サーマルヘッド１２と、サーマルヘッド１２を支持する第１支持部材１４と、軸３６を介して第１支持部材１４に相対回動可能に組み合わされる第２支持部材１６と、第２支持部材１６に支持され、第１支持部材１４に対する第２支持部材１６の回動に伴い、サーマルヘッド１２と協働して印刷用紙Ｐを挟持する作用位置とサーマルヘッド１２から離隔して印刷用紙Ｐを解放する非作用位置との間で変位するプラテン１８と、プラテン１８を作用位置に解除可能に係止する係止機構とを備えて構成される。
【００６７】
係止機構は、プラテン１８の作用位置と非作用位置との間の移動軌跡に沿って第１支持部材１４に設けられ、プラテン１８が作用位置にあるときに、プラテン１８の軸部４０を回転自在に受容する軸受溝４６と、第１支持部材１４に回動可能に取着され、作用位置にあるプラテン１８にその回転を許容しつつ係合して、プラテン１８の軸部４０を軸受溝４６内に係留する係合部材９２とを備える。係合部材９２は、第１支持部材１４上に位置する回動中心９４と、プラテン回転軸線方向に見て軸受溝４６の内側に突出可能な縁部９６とを備える。
【００６８】
図示実施形態では、係合部材９２は、略Ｕ字状の外形を有し、その一端の作用領域に、回動中心９４及び縁部９６が形成される。回動中心９４は、係合部材９２を第１支持部材１４の一方の側壁２２に回動自在に取り付ける軸９４によって構成される。したがって係合部材９２は、第１支持部材１４の側壁２２の表面（例えば外面）に沿って、軸９４を中心に回動自在になっている。また、係合部材９２の作用領域から離れた他端領域には、軸９４を中心として係合部材９２を回動操作するための操作部分９２ａが形成される。
【００６９】
プラテン１８が非作用位置から作用位置へ移動する間に、プラテン１８の軸部４０は、その両端の突出部分４０ａが対応の軸受溝４６に挿入される。軸部４０の突出部分４０ａが軸受溝４６の底縁に隣接する位置まで挿入された時点で、プラテン１８が作用位置に到達する。なお、各突出部分４０ａには、一般的なラジアル軸受９８を装着しておくことが好ましい。図示のように、係合部材９２の縁部９６が軸受溝４６内に突出する位置にあるときに、縁部９６と軸受溝４６の底縁とは、それらの間に軸部４０の突出部分４０ａ（又は軸受９８）を受容可能な距離だけ互いに離れて配置される。したがって、プラテン１８が作用位置にあるときに、係合部材９２をその縁部９６が軸受溝４６内に突出する位置に配置すると、軸部４０の突出部分４０ａ（又は軸受９８）は、縁部９６と軸受溝４６の底縁との間に受容される。
【００７０】
図１４を参照して、係合部材９２の構成をさらに特定する。なお図１４は、係合部材９２の作用領域のみを代表的かつ概略的に示す。係合部材９２の縁部９６は、作用位置にあるプラテン１８の軸部４０の軸受９８にプラテン回転軸線方向に見て軸受溝４６の内側で係合する係合点１００を有する。さらに縁部９６は、係合点１００に隣接して、係合部材９２の回動中心（軸）９４からの距離が係合点１００よりも大きくなる係止領域１０２を有する。これら回動中心９４、係合点１００及び係止領域１０２は、プラテン１８を作用位置に固定的に保持するような相対位置関係を有する。
【００７１】
図示のように、係合部材９２の縁部９６がプラテン軸部４０の軸受９８に係合点１００で当接されているときには、軸受９８は軸受溝４６の少なくとも底縁及び係合部材９２に対向する側縁に当接される。この状態で、プラテン１８は作用位置に置かれる。そして、この状態での回動中心９４と係合点１００との間の距離Ｄ１よりも大きい距離Ｄ２が、回動中心９４と係合点１００の図で直下に隣接する係止領域１０２との間に規定される。このような構成によれば、図示の状態からプラテン軸部４０の軸受９８を軸受溝４６から上方へ引き出そうとしても、係合部材９２は、その縁部９６の係止領域１０２が軸受９８の外周面に衝合して、軸受９８の引き出し動作に追従する方向（図で反時計方向）への回動を阻止されるので、軸受９８すなわち軸部４０の突出部分４０ａを軸受溝４６内に固定的に係留することになる。その結果、プラテン１８が作用位置に固定的に保持される。
【００７２】
図示実施形態では、係合部材９２の係止領域１０２は、回動中心９４からの距離が係合点１００よりも漸増的に大きくなる湾曲形状を有している。しかしこれに限定されず、係合点１００に隣接して回動中心９４からの距離が局部的に大きくなる係止領域１０２を、縁部９６に形成することもできる。
【００７３】
また、図１３に示すように、係合部材９２と第１支持部材１４との間には、プラテン１８が作用位置にあるときに、縁部９６が軸受溝４６内に突出して軸部４０の突出部分４０ａ又は軸受９８に係合する方向へ、軸９４を中心として係合部材９２を回転付勢する弾性部材１０４を設置することが有利である。この構成によれば、プラテン１８を作用位置に配置する際に、軸部４０の突出部分４０ａを軸受溝４６に挿入する動作に応じて、係合部材９２が弾性部材１０４の弾性的付勢力下で自動的に回動して縁部９６が突出部分４０ａ又は軸受９８に係合し、それにより突出部分４０ａを軸受溝４６内に係留する。
【００７４】
係合部材９２のこのような動作を、図１５を参照して説明する。まず、初期状態では係合部材９２は、弾性部材１０４の付勢力により、縁部９６が軸受溝４６内に突出する位置に配置される（図１５（ａ））。この状態から、プラテン軸部４０の突出部分４０ａを軸受溝４６に挿入すると、軸受９８の外周面が係合部材９２の縁部９６に衝突し、それにより係合部材９２を、弾性部材１０４の付勢力に抗して、突出部分４０ａの挿入動作に追従する方向（図で時計方向）へ回動させる（図１５（ｂ））。さらに継続してプラテン軸部４０の突出部分４０ａを軸受溝４６内に押し込むと、所定挿入位置を越えた時点から、係合部材９２が弾性部材１０４の付勢力により図で反時計方向へ回動し始める。そして、軸受９８が軸受溝４６の底縁に接触する位置に到達したときに、係合部材９２は初期位置に復帰し、上記したように係合点１００で軸受９８に当接されるとともに、係止領域１０２の作用により軸受９８及び突出部分４０ａを軸受溝４６内に係留する（図１５（ｃ））。
【００７５】
プラテン１８を作用位置から非作用位置へ移動させる際には、作業者が係合部材９２の操作部分９２ａを操作して、係合部材９２を弾性部材１０４の付勢力に抗して図で時計方向へ回動させる。それにより、係合部材９２の縁部９６とプラテン軸部４０の軸受９８との相互係合が解除されるので、軸受９８及び突出部分４０ａを軸受溝４６から自在に引き出すことができる。
【００７６】
上記構成を有するサーマルプリンタ９０によれば、係止機構を構成する係合部材９２が、回動中心９４と縁部９６との間の距離によって代表される寸法を、少なくとも所要の係止作用を発揮し得る程度に確保できればよいので、従来の揺動式フックからなる係合部材に比べて、係合部材９２の全体寸法、特に回動中心９４と係止点１００との間の距離を著しく縮小することができる。したがって係合部材９２は、強化金属等の剛性材料から作製せずとも、サーマルヘッド１２からプラテン１８に負荷される接触圧力や、動力伝達機構５２（図１）からプラテン軸部４０に負荷される剪断力等の外力に、十分に耐えることができる。この場合、成形性に優れた樹脂材料から係合部材９２を作製すれば、サーマルプリンタ９０の製造コストの上昇を抑制することができる。
【００７７】
このように、係合部材９２の材料剛性をある程度無視できることから、例えば自己潤滑性に優れた材料から係合部材９２を作製することもできる。この場合、プラテン軸部４０の軸受９８を省略して、突出部分４０ａを直接的に係合部材９２によって係留することができる。
【００７８】
【発明の効果】
以上の説明から明らかなように、本発明によれば、開閉可能な印字部を有するサーマルプリンタにおいて、部品点数の増加、製造コストの上昇、用紙補給／交換作業性の悪化等の不都合を生じることなく、印字作業の間、係止機構により一対の支持部材を閉じた状態に固定的に係止して、印字部のサーマルヘッドとプラテンとを作用位置に確実かつ安定的に保持することが可能になる。したがって本発明によれば、安定した印字作業を遂行できる高性能のサーマルプリンタが提供される。
【図面の簡単な説明】
【図１】本発明の第１の実施形態によるサーマルプリンタの、印字部開放時の概略斜視図である。
【図２】図１のサーマルプリンタにおける係止機構の構成を概略で示す部分断面正面図である。
【図３】図１のサーマルプリンタにおける係止機構の動作説明図で、（ａ）プラテン軸を軸受溝へ挿入する直前の状態、（ｂ）プラテン軸を軸受溝へ挿入している状態、及び（ｃ）プラテン軸を軸受溝に係留した状態を示す。
【図４】図１のサーマルプリンタにおける係止機構の変形例を示す概略図である。
【図５】図１のサーマルプリンタにおける係止機構の他の変形例を示す概略図で、（ａ）係留前の状態、及び（ｂ）係留中の状態を示す。
【図６】図１のサーマルプリンタにおける係止機構のさらに他の変形例を示す概略図である。
【図７】図１のサーマルプリンタにおける係止機構のさらに他の変形例を示す概略図である。
【図８】本発明の第２の実施形態によるサーマルプリンタの、係止機構の構成を示す概略正面図である。
【図９】図８の係止機構の変形例を示す概略図である。
【図１０】図８の係止機構の他の変形例を示す概略図である。
【図１１】図８の係止機構のさらに他の変形例を示す概略図である。
【図１２】本発明の第３の実施形態によるサーマルプリンタの、係止機構の構成を示す概略正面図である。
【図１３】本発明の第４の実施形態によるサーマルプリンタの、印字部開放時の概略斜視図である。
【図１４】図１３のサーマルプリンタにおける係止機構の構成を概略で示す拡大正面図である。
【図１５】図１３のサーマルプリンタにおける係止機構の動作説明図で、（ａ）プラテン軸を軸受溝へ挿入する直前の状態、（ｂ）プラテン軸を軸受溝へ挿入している状態、及び（ｃ）プラテン軸を軸受溝に係留した状態を示す。
【符号の説明】
１２…サーマルヘッド
１４…第１支持部材
１６…第２支持部材
１８…プラテン
３６…軸
４０…軸部
４４…軸受部材
４６…軸受溝
４８…受容部分
５６、６６、８０、１０４…弾性部材
６４、７６、９２…係合部材
９４…回動中心
９６…縁部
１００…係合点
１０２…係止領域[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermal printer.
[0002]
[Prior art]
Thermal printers equipped with a thermal printing section with a thermal head and a platen have a relatively small number of parts and are easy to miniaturize. Therefore, they are widely used as cash printers, portable terminal devices, ATM printers, etc. Yes. In this type of thermal printer, a thermal head and a platen are attached to a pair of support members that can be opened and closed to facilitate replenishment / replacement of printing paper (that is, roll paper) loaded in roll form. A printer that is individually mounted and configured to be openable and closable is known. The thermal printer having such an openable / closable printing unit is in a state in which both the supporting members are opened and the thermal head and the platen are sufficiently separated from each other when the newly supplied / replaced roll paper is set in the print standby state. For example, by placing the front end portion of the roll paper on the platen and then closing both supporting members, there is an advantage that the paper can be set easily and quickly.
[0003]
In the above-described thermal printer having an openable / closable printing unit, the thermal head and the platen are in a predetermined relative positional relationship so that stable printing can be performed while the printing unit and the pair of support members are closed. It is required to hold. In particular, in a line thermal printer that performs printing by electrically scanning a large number of heating elements of a thermal head that is fixedly arranged with respect to a rotating platen, a predetermined contact pressure required for printing work between the thermal head and the platen. Therefore, in the case of having the above-described printing unit opening / closing structure, the printing unit is closed, that is, the working position while maintaining such contact pressure while the printing unit and the pair of support members are closed. It is necessary to hold it fixedly. Therefore, a printing unit open / close type thermal printer is generally provided with a locking mechanism for locking the printing unit and the pair of support members fixedly and releasably in a closed position during a printing operation. As such a locking mechanism, a mechanism using a dedicated engaging member such as a swinging hook (see, for example, Japanese Patent Laid-Open No. 5-104818), or a mechanism using a contact pressure between the thermal head and the platen. (See, for example, JP-A-8-505576).
[0004]
[Problems to be solved by the invention]
In the above-described locking mechanism in the conventional print unit open / close type thermal printer, when a dedicated engaging member such as a swinging hook is used, the total weight of the printer increases due to an increase in the number of parts, or the engaging member There is a concern that the manufacturing cost may increase in order to ensure the durability and operation reliability of the device itself. Further, in this configuration, the operator performs a step operation (for example, using both hands) to release the manual operation for releasing the locking action between the support members by the engagement member and the manual operation for opening the pair of support members after the lock release. And there is a problem that consumes time for replenishment / replacement of roll paper.
[0005]
In particular, the swinging hook is attached to a first support member that supports the thermal head, and is an engagement member that releasably engages a shaft portion of a platen that is rotatably supported by the second support member. In the case of being configured, in order to enable smooth engagement / disengagement between the swinging hook and the platen shaft part, the platen shaft part is attached to the first support member while being anchored to the swinging hook. It is preferable to have some play. However, such play of the platen shaft portion causes a relative positional shift between the thermal head and the platen during the printing operation, and there is a concern that the printing quality is affected.
[0006]
Further, in this configuration, the contact pressure applied from the thermal head to the platen and the shearing force applied from the platen drive source to the platen shaft while the printing unit is held at the operating position are swayed from the platen shaft. Since it is transmitted to the moving hook, the swinging hook needs to be made of a rigid material such as a reinforced metal, particularly when the distance from the rotation center to the platen engagement point is large. The use of such a rigid material can increase the weight and manufacturing cost of the thermal printer.
[0007]
Further, in the configuration in which the printing unit is releasably locked at the closed position, that is, the operating position by using the contact pressure between the thermal head and the platen, the contact pressure is applied to the printing unit and the pair while the platen is in the operating position. Since the thermal head and the platen are relatively positioned so as to act in the direction of holding the supporting member in the closed position, the thermal head is resisted against the contact pressure when both the supporting members are opened. And the platen must be dissociated. As a result, excessive labor is consumed every time printing paper is replenished / replaced, and there is a concern that workability will deteriorate and printer components will deteriorate.
[0008]
Accordingly, it is an object of the present invention to provide a thermal printer having a printable portion that can be opened and closed during a printing operation without causing inconveniences such as an increase in the number of parts, an increase in manufacturing cost, and a deterioration in paper supply / replacement workability. A new and useful locking mechanism that can securely and stably hold the thermal head and the platen of the printing unit in the operating position, while being able to lock the support member in a closed state, and is stable The object is to provide a high-performance thermal printer capable of performing printing operations.
[0009]
[Means for Solving the Problems]
To achieve the above object, the invention described in claim 1 includes a thermal head, a first support member that supports the thermal head, a second support member that is combined with the first support member so as to be relatively movable, 2 An operation position that is supported by the support member and moves the second support member relative to the first support member to cooperate with the thermal head to clamp the printing paper and a non-operation position that releases the printing paper away from the thermal head And a latching mechanism for releasably latching the platen at the operating position, the latching mechanism includes a bearing member coupled to the platen so as to be movable in the rotational axis direction. An elastic member for elastically urging the bearing member with respect to the platen in the direction of the rotation axis; and a first supporting member provided under the elastic urging force of the elastic member when the platen is in the operating position. A holding portion that removably engages with the bearing member to hold the bearing member in a predetermined position and holds the platen in the operating position rotatably via the bearing member. A thermal printer is provided.
[0010]
According to a second aspect of the present invention, in the thermal printer according to the first aspect, the bearing member includes an outer ring portion having a cone-shaped contour centering on the rotation axis, and the holding portion is a cone shape of the outer ring portion. A thermal printer is provided that includes a receiving portion having a concave contour that conforms to the contour, and when the platen is in the working position, the receiving portion closely receives the outer ring portion under elastic biasing force and holds it stationary.
[0011]
According to a third aspect of the present invention, in the thermal printer according to the first or second aspect, the platen includes a cylindrical main body and a shaft portion that protrudes concentrically so as to be axially movable from both axial end surfaces of the cylindrical main body. And the bearing member is mounted on at least one protruding portion of the shaft portion to provide a thermal printer that receives the elastic biasing force of the elastic member.
[0014]
Claim 4 According to the invention, the thermal head, the first support member that supports the thermal head, the second support member that is combined with the first support member so as to be relatively movable, and the second support member are supported by the first support member. A platen that is displaced between a working position for clamping the printing paper in cooperation with the thermal head and a non-working position for releasing the printing paper while being separated from the thermal head in association with the movement of the second support member relative to the thermal head. In the thermal printer having a locking mechanism that releasably locks to the operating position, the locking mechanism is provided on the first support member along the movement trajectory between the operating position and the non-operating position of the platen, When the platen is in the operating position, a bearing groove that rotatably receives the shaft portion of the platen and a second support member are movably attached to the first support member, and the platen shaft portion is engaged with the first support member. Bearing groove An engaging member that is moored to the first support member, and the direction of the force applied to the engagement member to release the engagement member from the first support member acts after the engagement member is released from the first support member. A thermal printer is provided that is substantially the same as the direction of a force applied to a second support member for moving from a position to a non-operating position.
[0015]
Claim 5 According to the invention, the thermal head, the first support member that supports the thermal head, the second support member that is combined with the first support member so as to be relatively movable, and the second support member are supported by the first support member. A platen that is displaced between a working position for clamping the printing paper in cooperation with the thermal head and a non-working position for releasing the printing paper while being separated from the thermal head in association with the movement of the second support member relative to the thermal head. In the thermal printer having a locking mechanism that releasably locks to the operating position, the locking mechanism is provided on the first support member along the movement trajectory between the operating position and the non-operating position of the platen, When the platen is in the working position, a bearing groove for rotatably receiving the shaft portion of the platen and the first support member are rotatably attached to the platen in the working position while allowing the platen to rotate. And an engaging member for anchoring the shaft portion of the platen in the bearing groove. The engaging member has a rotation center located on the first support member, and the bearing groove as viewed in the platen rotation axis direction. The engaging member has an engaging point that engages with the platen in the working position in the platen rotation axis direction and engages with the inside of the bearing groove. Adjacent, there is a locking region where the distance from the rotation center of the engagement member is greater than the engagement point, and the rotation center, the engagement point and the locking region hold the platen in the working position fixedly. There is provided a thermal printer characterized by having such a relative positional relationship.
[0016]
Claim 6 The invention described in claim 5 The thermal printer according to claim 1, further comprising an elastic member that elastically biases the engaging member in a direction in which the edge portion projects inward of the bearing groove when viewed in the platen rotation axis direction.
[0017]
Claim 7 The invention described in claim 1 6 In the thermal printer according to any one of the above, a drive mechanism that rotationally drives the platen is installed in the first support member, and the platen is operatively connected to the drive mechanism when the platen is in the operating position. A thermal printer is provided in which the platen is separated from the drive mechanism when the is in the inoperative position.
[0018]
Claim 8 The invention described in claim 1 7 In the thermal printer according to any one of the above, the second support member is combined with the first support member so as to be rotatable relative to the first support member, and the platen is moved to the operating position as the second support member rotates relative to the first support member. A thermal printer is provided that is displaced between non-acting positions.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Throughout the drawings, the same or similar components are denoted by common reference numerals.
FIG. 1 is a schematic perspective view of a thermal printer 10 having an openable / closable printing unit according to an embodiment of the present invention when the printing unit is opened, and FIG. 2 is a part schematically showing a configuration of a locking mechanism of the thermal printer 10. FIG. 3 is a cross-sectional front view, and FIG.
[0020]
The thermal printer 10 is supported by a thermal head 12, a first support member 14 that supports the thermal head 12, a second support member 16 that is combined with the first support member 14 so as to be relatively movable, and a second support member 16. And a platen 18 that moves relative to the thermal head 12 as the second support member 16 moves relative to the first support member 14. The thermal printer 10 according to the illustrated embodiment has a form that can be used mainly in conjunction with and connected to a portable terminal device, but the application of the thermal printer according to the present invention is not limited.
[0021]
The first support member 14 integrally includes a bottom wall 20 having a flat portion and a curved portion, and flat side walls 22 extending upright along both side edges of the bottom wall 20. The flat portion of the bottom wall 20 and a portion of the side walls 22 adjacent thereto define a main region 24 on which the thermal head 12 and a platen drive mechanism (described later) are mounted on the first support member 14. Further, the curved portion of the bottom wall 20 and the other portions of the side walls 22 adjacent thereto are subregions that at least partially receive the printing paper P (that is, the roll paper R) that is continuous in a web shape wound in a roll shape. 26 is defined on the first support member 14 adjacent to the main region 24.
[0022]
The second support member 16 integrally includes a top wall 28 having a flat portion and a curved portion, and flat side walls 30 that extend upright along both side edges of the top wall 28. The flat portion of the top wall 28 and a portion of the side walls 30 adjacent thereto define a main region 32 on which the platen 18 is mounted on the second support member 16. Further, the curved portion of the top wall 28 and the other portions of the side walls 30 adjacent to the curved portion of the top wall 28 have a sub-region 34 surrounding at least partially the roll paper R on the second support member 16 adjacent to the main region 32. Define.
[0023]
The first support member 14 and the second support member 16 are mutually rotatable in the vicinity of the end portions of the sub-regions 26 and 34 on the side away from the main regions 24 and 32 via a common shaft 36. Connected. As a result, the first support member 14 and the second support member 16 can perform an opening / closing operation for opening and closing the main regions 24 and 32 and the sub regions 26 and 34 in a rotational manner. A printing unit composed of the platen 18 can be opened and closed.
[0024]
The thermal head 12 is a flat plate member having a substantially flat print surface in which a heating element is arranged at a predetermined position, and an elastic body with the print surface facing the sub region 26 side on the main region 24 of the first support member 14. (For example, a leaf spring shown in the figure) 38 is supported on the first support member 14 so as to be passively displaced. The thermal head 12 can have, for example, a line dot structure in which printing is performed by electrically scanning a number of heating elements aligned on the printing surface. The elastic body 38 is configured to bend by an external force and load the thermal head 12 with an elastic urging force in a direction approaching the sub-region 26, so that when the platen 18 is in a working position described later, A predetermined contact pressure required for the printing operation is generated between the head 12 and the platen 18.
[0025]
The platen 18 includes a cylindrical main body 39 preferably made of an elastic body such as rubber, and a shaft portion 40 fixed along the central axis of the main body 39, and the main portion of the second support member 16 is formed by the shaft portion 40. A region 32 is rotatably mounted. The platen 18 sandwiches the printing paper P fed out from the roll paper R under pressure between the thermal head 12 and the platen 18 to realize stable printing on the printing paper P. And at the same time, it functions as a driving roller for continuously feeding the printing paper P by frictional force. The shaft portion 40 protrudes in the axial direction from both end surfaces in the axial direction of the platen 18, and freely rotates in support holes 42 formed through the corresponding portions of the side walls 32 constituting the main region 32 of the second support member 16. Inserted.
[0026]
The platen 18 is moved away from the thermal head 12 from an operating position (not shown) for clamping the printing paper P in cooperation with the thermal head 12 as the second support member 16 rotates with respect to the first support member 14. In this way, a displacement (that is, a revolving operation) is performed along a circular arc trajectory over a desired angle with respect to the shaft 36 between the non-operating position (FIG. 1) where the printing paper P is released. While the platen 18 is in the operating position, the rotation axis of the platen 18, that is, the shaft portion 40, is disposed substantially parallel to the axis of the shaft 36 that interconnects the first and second support members 14 and 16.
[0027]
Bearing members 44 are mounted on the shaft portions 40 of the platen 18 at the portions 40 a that protrude outward from the side walls 30 of the second support member 16. On the other hand, on both side walls 22 of the first support member 14, bearing grooves 46 extending along the displacement (revolution) trajectory of the platen 18 are formed in the boundary region between the main region 24 and the sub region 26 from the upper ends of the side walls 22. Each is formed over a predetermined length. Further, the receiving portions 48 are recessed in the side walls 22 of the first support member 14 adjacent to the respective bearing grooves 46 on the mutually opposing surfaces. When the platen 18 is in the operating position, both projecting portions 40a of the shaft portion 40 are received in the corresponding bearing grooves 46 through gaps, and both bearing members 44 are fitted into the corresponding receiving portions 48 as will be described later. . Accordingly, the platen 18 is rotatably supported by the first support member 14 via the pair of bearing members 44.
[0028]
Further, a driven wheel 50 is fixed to the shaft portion 40 of the platen 18 at the tip of a protruding portion 40 a that protrudes outward from one side wall 30 of the second support member 16. On the other hand, a power transmission mechanism 52 (for example, a gear train) and a drive source 54 (for example, an electric motor) are installed in the main region 24 of the first support member 14 as a drive mechanism for rotationally driving the platen 18. When the platen 18 is in the operating position, the driven wheel 50 engages with the power transmission mechanism 52 and is operatively connected to the drive source 54 via the power transmission mechanism 52. Thereby, the torque of the drive source 54 is transmitted to the shaft portion 40 and the platen 18 rotates. Further, as the platen 18 is displaced from the operating position to the non-operating position, the driven wheel 50 is detached from the power transmission mechanism 52, thereby separating the platen 18 from the drive source 54. The thermal head 12 and the drive source 54 can be connected to a control circuit board (not shown) and a battery (not shown) that can be disposed adjacent to the main region 24 of the first support member 14.
[0029]
In the thermal printer 10, the first contact pressure is maintained between the thermal head 12 and the platen 18 while maintaining the predetermined contact pressure between the thermal head 12 and the platen 18 so that the stable printing operation can be performed while the platen 18 is in the operating position. And it is necessary to hold | maintain the 2nd supporting members 14 and 16 fixedly in a closed position. For this purpose, the thermal printer 10 is provided with a locking mechanism for releasably locking the platen 18 to the operating position during the printing operation.
[0030]
In the illustrated embodiment, the locking mechanism is a pair of bearing members 44 that are coupled to the platen 18 so as to be movable in the rotational axis direction, and elastically urges the bearing members 44 in the rotational axis direction with respect to the platen 18. A pair of elastic members 56 and a first support member 14 are provided on the first support member 14 so as to be detachably engaged with both bearing members 44 under the elastic biasing force of both elastic members 56 when the platen 18 is in the operating position. The bearing member 44 is fixedly held at a predetermined position, that is, a pair of receiving portions 48 described above.
[0031]
More specifically, as shown in FIG. 2, the shaft portion 40 of the platen 18 includes a core portion 40b that passes through the main body 39 of the platen 18 along the rotation axis 18a and is fixed to the main body 39, and a core portion 40b. The above-mentioned pair of projecting portions 40a that are small in diameter and project in the axial direction concentrically from both axial end surfaces of the core portion 40b are integrally connected to each other. An annular shoulder surface 40c is formed between the protruding portion 40a and the core portion 40b. In each protruding portion 40a, the inner ring portion (not shown) of the bearing member 44 described above cannot be rotated through a well-known connecting element (not shown) such as a spline and can move in the rotation axis direction over a predetermined range. Connected to
[0032]
Each of the pair of bearing members 44 includes an outer ring portion 44 a having a cone-shaped (conical frustum in the drawing) -shaped contour centered on the rotation axis 18 a of the platen 18. The outer ring portion 44a is rotatable with respect to the inner ring portion while resisting radial load and thrust load. Therefore, the outer ring portion 44a is rotatable with respect to the shaft portion 40 about the rotation axis 18a and is movable in the axial direction over a predetermined range. ing. Each outer ring portion 44 a is arranged with its small-diameter end surface facing the distal end side of each protruding portion 40 a of the shaft portion 40.
[0033]
Each of the pair of elastic members 56 is installed between each annular shoulder surface 40c of the shaft portion 40 and the inner ring portion of each bearing member 44 opposed thereto so as to be elastically compressible in the axial direction. Preferably, each elastic member 56 includes an annular shoulder surface 40c of the shaft portion 40 and an inner ring portion of the bearing member 44 when the bearing member 44 is at the outer limit position of the axial movement range on the protruding portion 40a of the shaft portion 40. Is held in an initial compressed state. Accordingly, each bearing member 44 can move from the outer limit position to the inner limit position of the axial movement range on the corresponding protruding portion 40a against the elastic biasing force of the corresponding elastic member 56. As the elastic member 56, a compression coil spring as illustrated can be advantageously used.
[0034]
Each of the pair of receiving portions 48 of the first support member 14 has a concave contour that matches the cone-shaped contour of the outer ring portion 44 a of the bearing member 44. Accordingly, each receiving portion 48 has a concave surface and can be in close contact with the tapered surface of the outer ring portion 44 a of the bearing member 44. When both the pair of bearing members 44 are at the outer limit position of the axial movement range (that is, when both elastic members 56 are in the initial compression state), the small-diameter end surfaces of the outer ring portions 44a of these bearing members 44 The distance between the two side walls 22 of the first support member 14 is larger than the distance between the two side walls 22, and the distance between the large-diameter end surfaces of the outer ring portion 44 a is smaller than the distance between the both side walls 22 of the first support member 14. Thus, the dimension of each component is set.
[0035]
The operation of the locking mechanism having the above configuration will be described with reference to FIGS.
When the second support member 16 is rotated about the shaft 36 with respect to the first support member 14 and the platen 18 is moved from the non-operation position to the operation position in FIG. 1, both the shaft portions 40 of the platen 18 are moved. The protruding portion 40a approaches the bearing grooves 46 of the side walls 22 of the first support member 14 (arrow A in FIG. 2). When the second support member 16 reaches a predetermined rotational position, the two bearing members 44 are at the edges of the side walls 22 that define the upper end openings of the corresponding bearing grooves 46 at the tapered surfaces of the outer ring portions 44a. Each collides (FIG. 3A).
[0036]
From this state, when the second support member 16 is pressed in a direction closer to the first support member 14, the outer ring portion 44a of both bearing members 44 is along the edge of the corresponding bearing groove 46 at its tapered surface. Slide. At this time, each bearing member 44 elastically compresses the corresponding elastic member 56 by the axial component force of the reaction that the tapered surface of the outer ring portion 44 a receives from the edge of the bearing groove 46, and the main body of the platen 18. It moves on each protrusion part 40a of the axial part 40 in the direction which approaches 39 (FIG.3 (b) arrow B). When both the bearing members 44 move until the distance between the small-diameter end surfaces of the outer ring portions 44 a is substantially equal to the distance between the both side walls 22 of the first support member 14, the both bearing members 44 are located between the both side walls 22. And the protruding portions 40a are received in the bearing grooves 46 (FIG. 3B).
[0037]
When the second support member 16 is further pressed in the direction approaching the first support member 14 from this state, the outer ring portions 44a of both bearing members 44 are on the inner surfaces of the side walls 22 of the first support member 14 at their small diameter end surfaces. Slide. Thereafter, when the entire small-diameter end surface of the bearing member 44 enters the corresponding receiving portion 48, the tapered surface of the outer ring portion 44 a follows the concave surface of the corresponding receiving portion 48 by the elastic biasing force of the corresponding elastic member 56. Each bearing member 44 moves on each projecting portion 40a of the shaft portion 40 in a direction away from the main body 39 of the platen 18 (arrow C in FIG. 3C). And finally, the outer ring portions 44a of both bearing members 44 are received in both receiving portions 48 substantially simultaneously with their tapered surfaces generally in close contact with the concave surfaces of the corresponding receiving portions 48, It is held stationary at a predetermined position. In this state, the platen 18 is rotatably supported by the first support member 14 in cooperation with the pair of bearing members 44 and the corresponding receiving portion, and is fixedly held at the operating position (FIG. 3). (C)).
[0038]
Note that while the pair of bearing members 44 mounted on the shaft portion 40 of the platen 18 are received by the corresponding receiving portions 48 provided in the first support member 14, the elastic biasing force of the elastic member 56 is the both bearings. Advantageously, the member 44 is loaded. According to this configuration, the outer ring portions 44a of the two bearing members 44 have their tapered surfaces closely contacted with the concave surfaces of the corresponding receiving portions 48 under the elastic biasing force of the elastic member 56, and are firmly held stationary. The As a result, the thermal head 12 and the platen 14 are securely and stably held at the operation positions during the printing operation, and the stable printing operation can be performed.
[0039]
When the platen 18 is moved from the non-operating position to the operating position, the second support member 16 is operated in a direction away from the first support member 14 from the state of FIG. As a result, pressure is applied to the tapered surface of the outer ring portion 44a of both bearing members 44 from the concave surface of the corresponding receiving portion 48, and each bearing member 44 is caused to correspond to the corresponding elastic member by the axial component of the pressure. 56 is moved on each protruding portion 40a of the shaft portion 40 in a direction approaching the main body 39 of the platen 18 while being elastically compressed. Then, after the outer ring portions 44a of the both bearing members 44 are detached from the corresponding receiving portions 48, the both bearing members 44 are detached from the first support member 14 through the state shown in FIG. Thereafter, the platen 18 can be displaced to the non-operation position by continuously rotating the second support member 16 toward the open position.
[0040]
According to the thermal printer 10 having the above-described configuration, the first and second members are used during the printing operation by using the bearing member 44 that is originally required for rotatably mounting the platen 18 to the first support member 14. Since the support members 14 and 16 are fixedly locked in the closed position, it is possible to avoid the use of a dedicated engagement member such as a swinging hook in a conventional thermal printer, and therefore the number of parts and the total weight of the printer can be avoided. Increases and manufacturing costs are prevented from increasing. In addition, the cooperation between the bearing member 44 and the receiving portion 48 enables the printing portion (the thermal head 12 and the platen 18) to be securely fixedly locked at the operating position during the printing operation, so that a stable printing operation can be performed. it can. In addition, the operator manually releases the locking action between the first and second support members 14 and 16 by the cooperation of the bearing member 44 and the receiving portion 48, and after releasing the lock, the support members 14 and 16. Since the manual operation of opening the paper sheet can be performed in a series of operations without distinction, the roll paper R can be replenished / replaced easily and quickly.
[0041]
Furthermore, the operating force required to open and close the first and second support members 14 and 16 (that is, to engage and disengage the locking mechanism) can be easily adjusted by adjusting the spring force of the pair of elastic members 56. Can be set and changed. This operating force can be set regardless of the contact pressure required between the thermal head 12 and the platen 18. Further, since the contact area between the tapered surface of the outer ring portion 44a of the bearing member 44 and the concave surface of the receiving portion 48 can be made relatively large, it is possible to reduce wear on both contact surfaces when the opening / closing operation is repeated.
[0042]
The thermal printer 10 according to the above-described embodiment can perform various deformations and corrections. For example, the bearing member 44 urged in the axial direction by the elastic member 56 may be installed on at least one protruding portion 40 a of the shaft portion 40 of the platen 18. In this case, a general bearing member that cannot move in the axial direction can be installed on the protruding portion 40a of the shaft portion 40 on the side where the bearing member 44 is not installed.
[0043]
Further, instead of the outer ring portion 44a of the bearing member 44 having the frustoconical contour described above, an outer ring portion 44b having a conical shape including an outer peripheral surface swelled in a spindle shape as shown in FIG. 4 is adopted. You can also. In this case, the first support member 14 can be formed with a receiving portion 48 ′ having a concave surface that matches the spindle-shaped outer peripheral surface of the outer ring portion 44 b. According to such a configuration, the outer ring portion 44b of the bearing member 44 can be held still more firmly on the receiving portion 48 'by increasing the mutual contact area.
[0044]
As the elastic member 56, a conical compression coil spring as shown in FIG. 5A may be employed instead of the above-described cylindrical compression coil spring. According to this configuration, the space S (FIG. 5B) between the bearing member 44 and the shoulder surface 40c of the shaft portion 40 when the elastic member 56 is compressed to the maximum is formed into a structure using a cylindrical compression coil spring. Since the size can be reduced in comparison, the dimension in the axial direction of the platen 18 and the dimension in the width direction of the thermal printer 10 can be further reduced.
[0045]
Also, as shown in FIG. 6, the pair of bearing members 44 mounted on the shaft portion 40 of the platen 18 are oriented so that the small-diameter end surfaces of the respective outer ring portions 44a face the main body 39 of the platen 18, It can also be arranged on both projecting portions 40a. In this case, the pair of elastic members 56 is installed between the driven wheel 50 fixed to the tip of the one protruding portion 40a and the bearing member 44, and the stopper 58 fixed to the tip of the other protruding portion 40a. And the bearing member 44. The receiving portion 48 that receives the outer ring portion 44 a of the bearing member 44 is formed on the outer surface of the side walls 22 of the first support member 14.
[0046]
Further, as shown in FIG. 7, the shaft portion 40 of the platen 18 includes a cylindrical core portion 60 having hollow regions 60 a at both ends in the axial direction, and a pair of parts accommodated in the hollow regions 60 a of the core portion 60. It is also possible to constitute the projecting portion 62. In this case, each protruding portion 62 is connected to the core portion 60 through a known connecting element (not shown) such as a spline so as not to rotate and to move in the rotation axis direction over a predetermined range. The elastic member 56 is accommodated in each hollow region 60a of the core portion 60 and elastically biases the corresponding protruding portion 62 outward in the axial direction. According to this configuration, the distance between the bearing member 44 and the shoulder surface of the shaft portion 40 (end surface 60b of the core portion 60) when the elastic member 56 is compressed to the maximum can be substantially eliminated. The direction dimension and the width direction dimension of the thermal printer 10 can be further reduced.
[0047]
8 to 11 employ an engaging member in the form of a swinging hook as a locking mechanism that releasably locks the printing unit (the thermal head 12 and the platen 18) to the operating position during a printing operation. Fig. 6 schematically shows some specific configurations of the locking mechanism of the thermal printer according to the second embodiment of the present invention. Note that the various locking mechanisms shown in these drawings can be mounted on the thermal printer 10 according to the first embodiment in place of the locking mechanism including the bearing member 44, the receiving portion 48, and the elastic member 56 described above. . Therefore, the same components as those of the thermal printer 10 are denoted by the same reference numerals and description thereof is omitted.
[0048]
The locking mechanism shown in FIG. 8 is provided on the first support member 14 along the movement trajectory between the operating position and the non-operating position of the platen 18, and when the platen 18 is in the operating position, the axis of the platen 18. The shaft groove 40 of the platen 18 is engaged with the bearing groove 46 that rotatably receives the portion 40 and the platen 18 that is movably attached to the first support member 14 while allowing its rotation. And the platen 18 in the working position is elastically pressed against the engaging member 64, and the platen 18 is fixed to the working position in cooperation with the engaging member 64. And an elastic member 66 to be held.
[0049]
More specifically, the engagement member 64 is integrally provided with an arm portion 64a extending in an L shape and a hook portion 64b projecting laterally in one end region of the arm portion 64a. The engagement member 64 is attached to the one side wall 22 of the first support member 14 via the shaft 68 in the other end region of the arm portion 64a away from the hook portion 64b. Thereby, the engaging member 64 is rotatable around the shaft 68 along the surface (for example, the outer surface) of the side wall 22 of the first support member 14. Here, the size and shape of each part of the engaging member 64 and the position of the shaft 68 on the engaging member 64 are such that the hook portion 64 b overlaps with the bearing groove 46 of the first support member 14 while the engaging member 64 is rotating. It is set to pass through the position to be
[0050]
While the platen 18 moves from the non-operating position to the operating position, the projecting portions 40 a at both ends of the shaft portion 40 of the platen 18 are loosely inserted into the corresponding bearing grooves 46. When the protruding portion 40a of the shaft portion 40 is inserted to a position adjacent to the bottom edge of the bearing groove 46, the platen 18 reaches the operating position. As shown in the figure, when the hook portion 64b of the engaging member 64 is positioned so as to overlap the bearing groove 46, the inner edge of the hook portion 64b (that is, the edge portion closer to the shaft 68) and the bottom edge of the bearing groove 46 Are arranged apart from each other by a distance that allows the protruding portion 40a of the shaft portion 40 to be received through a slight gap. Therefore, when the engaging member 64 is disposed at a position where the hook portion 64b overlaps the bearing groove 46 when the platen 18 is in the operating position, the protruding portion 40a of the shaft portion 40 is connected to the inner edge of the hook portion 64b and the bearing groove. It is received through a slight gap between the bottom edge of 46.
[0051]
The elastic member 66 loads the shaft portion 40 with an elastic biasing force that acts in a direction in which the protruding portion 40 a of the shaft portion 40 received in the bearing groove 46 is pushed out from the bearing groove 46 along the bearing groove 46. Therefore, when the engaging member 64 is disposed at a position where the hook portion 64 b overlaps the bearing groove 46 when the platen 18 is in the operating position, the protruding portion 40 a of the shaft portion 40 is near the bottom edge of the bearing groove 46. In response to the elastic biasing force of the elastic member 66, the elastic member 66 comes into contact with the inner edge of the hook portion 64b under pressure. In this state, the protruding portion 40a of the shaft portion 40 is fixedly anchored in the bearing groove 46 by the cooperation of the engaging member 64 and the elastic member 66, whereby the platen 18 is fixedly held in the operating position. The From this state, when the engaging member 64 is rotated and separated from the protruding portion 40 a of the shaft portion 40, the protruding portion 40 a of the shaft portion 40 is separated from the bottom edge of the bearing groove 46 by the biasing force of the elastic member 66. Pushed up. As a result, the platen 18 moves from the operating position.
[0052]
Preferably, the engaging member 64 is elastically biased toward the position where the hook portion 64b anchors the protruding portion 40a of the shaft portion 40 in the bearing groove 46 by a biasing means such as a spring (not shown). The According to this configuration, when the platen 18 is disposed at the operating position, the engagement member 64 is subjected to the elastic biasing force of the biasing means according to the operation of inserting the protruding portion 40a of the shaft portion 40 into the bearing groove 46. Thus, the hook portion 64b engages with the protruding portion 40a, and the protruding portion 40a is anchored in the bearing groove 46.
[0053]
When operating the above-described locking mechanism, the operator continuously performs a manual operation of releasing the printing unit locking action by the engaging member 64 and a manual operation of opening the printing unit after releasing the locking with one hand. It can be carried out. To explain this unlocking operation, the operator first operates the engaging member 64 with one hand from the mooring position shown in FIG. 8 on the operating portion 64c extending in the vicinity of the hook portion 64b of the engaging member 64. , The shaft 68 is rotated counterclockwise in the figure. Accordingly, the protruding portion 40 a of the shaft portion 40 of the platen 18 is detached from the engaging member 64 and is pushed up away from the bottom edge of the bearing groove 46 by the biasing force of the elastic member 66. Accordingly, the platen 18 moves from the operating position.
[0054]
While the platen 18 moves from the operating position, the protruding portion 40 a of the shaft portion 40 is pressed against the side edge of the bearing groove 46 by the contact pressure applied to the platen 18 from the thermal head 12 (FIG. 1). Therefore, the elastic biasing force applied to the shaft portion 40 from the elastic member 66 causes friction generated between the thermal head 12 and the platen 18 and between the protruding portion 40a of the shaft portion 40 and the side edge of the bearing groove 46. When the force becomes lower than the force, the movement of the protruding portion 40a in the bearing groove 46 stops, and the platen 18 stops at its intermediate position. In this state, since the hook portion 64b of the engaging member 64 interferes with the protruding portion 40a in the bearing groove 46, the engaging member 64 can no longer anchor the protruding portion 40a. Therefore, the operator releases his / her hand from the operating portion 64c of the engaging member 64 and operates the second support member 16 (FIG. 1) with the same hand to completely remove the protruding portion 40a of the shaft portion 40 from the bearing groove 46. After separation, the platen 18 can be moved to the non-acting position.
[0055]
As described above, in the thermal printer having the above-described locking mechanism, the operator manually operates the engagement member 64 to release the mooring action of the platen shaft portion 40 and moves the platen 18 to the non-action position after the mooring is released. Since manual operation can be carried out continuously with one hand, the roll paper R (FIG. 1) can be replenished / replaced easily and quickly. Note that the above-described locking mechanism can be installed on each of the side walls 22 of the first support member 14 in association with the protruding portions 40 a at both ends of the platen shaft portion 40.
[0056]
The elastic member 66 can be composed of various elastic elements such as a torsion coil spring shown in FIG. 9 in addition to the compression coil spring shown in FIG. Further, as shown in FIG. 10, the thermal printer is provided with a switch mechanism 70 for detecting that the printing unit is in the working position, and the platen shaft unit 40 operates the operation member 72 of the switch mechanism 70. In this case, by providing the operating member 72 with a recovery spring 74, the recovery spring 74 can be configured to perform the same function as the elastic member 66. In this configuration, the independent elastic member 66 can be omitted.
[0057]
In the above-described locking mechanism, the hook portion 64b of the engagement member 64 and the protruding portion 40a of the platen shaft portion 40 can be smoothly engaged / disengaged in a state of being anchored to the hook portion 64b. The protruding portion 40 a of the shaft portion 40 preferably has some play with respect to the bearing groove 46. In particular, as shown in FIG. 11, in order to increase the anchoring holding force of the engaging member 64 with respect to the protruding portion 40a, when the hook portion 64b has an acute tip, the contact point P between the hook portion 64b and the protruding portion 40a is Since it is disposed at a position lower than the apex portion of the protruding portion 40 a in the bearing groove 46, it is essential to provide a play G that allows the protruding portion 40 a to move in the bearing groove 46 during the rotation of the engaging member 64. become. Also in this case, according to the configuration of the locking mechanism described above, the elastic member 66 elastically presses the protruding portion 40a of the shaft portion 40 against the hook portion 64b, so that the platen 18 is stably held at the operating position, The influence on print quality is eliminated.
[0058]
FIG. 12 shows how the thermal printer according to the third embodiment of the present invention adopts an engaging member having a rocking hook configuration as a locking mechanism for releasably locking the printing portion at the operating position. The structure of a mechanism is shown schematically. This locking mechanism can be mounted on the thermal printer 10 according to the first embodiment instead of the above-described locking mechanism including the bearing member 44, the receiving portion 48, and the elastic member 56. Therefore, the same components as those of the thermal printer 10 are denoted by the same reference numerals and description thereof is omitted.
[0059]
This locking mechanism is provided on the first support member 14 along the movement trajectory between the operating position and the non-operating position of the platen 18, and when the platen 18 is in the operating position, the shaft portion 40 of the platen 18 is moved. A bearing groove 46 that is rotatably received, and an engagement that is movably attached to the second support member 16 and engages the first support member 16 to anchor the shaft portion 40 of the platen 18 in the bearing groove 46. And a member 76.
[0060]
Specifically, the engaging member 76 includes an attachment portion 76a, a hook portion 76b extending in an L shape from the attachment portion 76a, and an operation portion extending from the attachment portion 76a on the opposite side of the hook portion 76b. 76c is integrally provided. The engaging member 76 is rotatably attached to the protruding portion 40a of the shaft portion 40 of the platen 18 at the attaching portion 76a. The shaft portion 40 of the platen 18 is also rotatably supported by a pair of frame portions 16 a provided on the free end side of the second support member 16. Thereby, the engaging member 76 is rotatable along the surface of the one frame portion 16 a of the second support member 16 around the protruding portion 40 a of the platen shaft portion 40.
[0061]
While the platen 18 moves from the non-operating position to the operating position, the projecting portions 40 a at both ends of the shaft portion 40 of the platen 18 are loosely inserted into the corresponding bearing grooves 46. When the protruding portion 40a of the shaft portion 40 is inserted to a position adjacent to the bottom edge of the bearing groove 46, the platen 18 reaches the operating position. A locking pin 78 protrudes from one side wall 22 of the first support member 14 at a position where the hook portion 76b of the engaging member 76 can be engaged when the platen 18 is in the operating position.
[0062]
As illustrated, between the engagement member 76 and the second support member 16, the hook portion 76 b is engaged with the locking pin 78 when the platen 18 is in the operating position, so that the shaft portion 40 is engaged. It is preferable to install an elastic member 80 that rotationally biases the engaging member 76 around the protruding portion 40a. According to this configuration, when the platen 18 is disposed at the operating position, the engaging member 76 is subjected to the elastic biasing force of the elastic member 80 according to the operation of inserting the protruding portion 40a of the shaft portion 40 into the bearing groove 46. Thus, the hook portion 76b engages with the locking pin 78, and thereby the protruding portion 40a is anchored in the bearing groove 46.
[0063]
When operating the above-described locking mechanism, the operator continuously performs a manual operation of releasing the printing unit locking action by the engaging member 76 and a manual operation of opening the printing unit after releasing the locking with one hand. It can be carried out. Referring to this unlocking operation, the operator first operates the engaging member 76 from the mooring position shown in FIG. 12 with the operating portion 76c with one hand, and counterclockwise in the figure with the shaft portion 40 of the platen 18 as the center. Rotate in the direction. Thereby, the hook portion 76 b of the engaging member 76 is detached from the locking pin 78. Therefore, the operator operates the second support member 16 with the same hand as it is without releasing the hand from the operation portion 76c of the engaging member 76, and completely removes the protruding portion 40a of the shaft portion 40 from the bearing groove 46. After that, the platen 18 can be moved to the non-acting position.
[0064]
As described above, in the thermal printer having the locking mechanism described above, the direction of the force applied to the engagement member 76 in order to disengage the engagement member 76 from the first support member 14 is such that the engagement member 76 is the first support member. The direction of the force applied to the second support member 16 to move the platen 18 from the working position to the non-working position after being detached from 14 is substantially the same. Accordingly, the operator can continuously perform the manual operation of releasing the mooring action of the platen shaft portion 40 by the engaging member 76 and the manual operation of moving the platen 18 to the non-acting position after the mooring is released. The roll paper R (FIG. 1) can be replenished / replaced easily and quickly. Note that the above-described locking mechanism can be installed on each of the pair of frame portions 16 a of the second support member 16 in association with the protruding portions 40 a at both ends of the platen shaft portion 40.
[0065]
The engaging members 64 and 76 having the above-described swing-type hooks are configured such that the contact pressure applied to the platen 18 from the thermal head 12 and the power transmission mechanism 52 ( Since the shearing force applied to the platen shaft 40 from FIG. 1) is received from the platen shaft 40, it needs to be made of a rigid material such as a reinforced metal. The use of such a rigid material can increase the weight and manufacturing cost of the thermal printer. FIG. 13 schematically shows a thermal printer 90 according to a fourth embodiment of the present invention that employs a novel engaging member that can solve such a problem. Since the thermal printer 90 has substantially the same configuration as that of the thermal printer 10 according to the first embodiment except for the configuration of the locking mechanism, the components common to both are denoted by the same reference numerals. Description is omitted.
[0066]
The thermal printer 90 includes a thermal head 12, a first support member 14 that supports the thermal head 12, a second support member 16 that is rotatably coupled to the first support member 14 via a shaft 36, and a second support member 16. As the second support member 16 rotates with respect to the first support member 14 and supported by the support member 16, the operation position for holding the print paper P in cooperation with the thermal head 12 is separated from the thermal head 12 and the print paper. The platen 18 is displaced between a non-operation position for releasing P, and a locking mechanism for releasably locking the platen 18 to the operation position.
[0067]
The locking mechanism is provided on the first support member 14 along the movement path between the operating position and the non-operating position of the platen 18, and rotates the shaft portion 40 of the platen 18 when the platen 18 is in the operating position. A bearing groove 46 that is freely received, and is rotatably attached to the first support member 14, and engages with the platen 18 in the operating position while allowing its rotation, and the shaft portion 40 of the platen 18 is engaged with the bearing groove. 46 and an engaging member 92 that is anchored in 46. The engagement member 92 includes a rotation center 94 located on the first support member 14 and an edge portion 96 that can project inside the bearing groove 46 when viewed in the platen rotation axis direction.
[0068]
In the illustrated embodiment, the engaging member 92 has a substantially U-shaped outer shape, and a rotation center 94 and an edge portion 96 are formed in an action region at one end thereof. The rotation center 94 is configured by a shaft 94 that rotatably attaches the engaging member 92 to one side wall 22 of the first support member 14. Therefore, the engaging member 92 is rotatable about the shaft 94 along the surface (for example, the outer surface) of the side wall 22 of the first support member 14. An operation portion 92 a for rotating the engagement member 92 about the shaft 94 is formed in the other end region away from the operation region of the engagement member 92.
[0069]
While the platen 18 moves from the non-operating position to the operating position, the projecting portions 40a at both ends of the shaft portion 40 of the platen 18 are inserted into the corresponding bearing grooves 46. When the protruding portion 40a of the shaft portion 40 is inserted to a position adjacent to the bottom edge of the bearing groove 46, the platen 18 reaches the operating position. It should be noted that a general radial bearing 98 is preferably attached to each protruding portion 40a. As shown, when the edge 96 of the engaging member 92 is in a position where it protrudes into the bearing groove 46, the edge 96 and the bottom edge of the bearing groove 46 are in between the protruding portion of the shaft portion 40. 40a (or bearing 98) are spaced apart from each other by an acceptable distance. Therefore, when the engaging member 92 is disposed at a position where the edge 96 protrudes into the bearing groove 46 when the platen 18 is in the operating position, the protruding portion 40a (or the bearing 98) of the shaft portion 40 is 96 and is received between the bottom edge of the bearing groove 46.
[0070]
With reference to FIG. 14, the structure of the engaging member 92 is further specified. FIG. 14 representatively and schematically shows only the action region of the engaging member 92. The edge portion 96 of the engagement member 92 has an engagement point 100 that engages with the bearing 98 of the shaft portion 40 of the platen 18 at the working position inside the bearing groove 46 when viewed in the platen rotation axis direction. Further, the edge portion 96 has an engagement region 102 adjacent to the engagement point 100, where the distance from the rotation center (axis) 94 of the engagement member 92 is larger than the engagement point 100. The rotation center 94, the engagement point 100, and the locking region 102 have a relative positional relationship such that the platen 18 is fixedly held at the operating position.
[0071]
As illustrated, when the edge 96 of the engagement member 92 is in contact with the bearing 98 of the platen shaft 40 at the engagement point 100, the bearing 98 faces at least the bottom edge of the bearing groove 46 and the engagement member 92. Abutting against the side edge. In this state, the platen 18 is placed in the working position. In this state, a distance D2 larger than the distance D1 between the rotation center 94 and the engagement point 100 is between the rotation center 94 and the engaging region 102 immediately below in the drawing of the engagement point 100. It is prescribed. According to such a configuration, even if the bearing 98 of the platen shaft portion 40 is to be pulled upward from the bearing groove 46 from the state shown in the drawing, the engaging member 92 has the locking region 102 of the edge portion 96 of the bearing 98. The rotation of the bearing 98 in the direction following the drawing operation of the bearing 98 (counterclockwise in the figure) is prevented, so that the bearing 98, that is, the protruding portion 40a of the shaft portion 40 is inserted into the bearing groove 46. They will be moored permanently. As a result, the platen 18 is fixedly held in the operating position.
[0072]
In the illustrated embodiment, the engagement region 102 of the engagement member 92 has a curved shape in which the distance from the rotation center 94 is gradually increased from the engagement point 100. However, the present invention is not limited to this, and the engaging region 102 adjacent to the engagement point 100 and having a locally increased distance from the rotation center 94 can be formed in the edge portion 96.
[0073]
Further, as shown in FIG. 13, when the platen 18 is in the operating position, the edge portion 96 protrudes into the bearing groove 46 between the engagement member 92 and the first support member 14, so that the shaft portion 40 It is advantageous to install an elastic member 104 that urges the engaging member 92 to rotate about the shaft 94 in a direction to engage with the protruding portion 40a or the bearing 98. According to this configuration, when the platen 18 is disposed at the operating position, the engaging member 92 is subjected to the elastic biasing force of the elastic member 104 according to the operation of inserting the protruding portion 40 a of the shaft portion 40 into the bearing groove 46. And the edge 96 engages the protruding portion 40 a or the bearing 98, thereby anchoring the protruding portion 40 a in the bearing groove 46.
[0074]
Such an operation of the engaging member 92 will be described with reference to FIG. First, in the initial state, the engaging member 92 is disposed at a position where the edge portion 96 protrudes into the bearing groove 46 by the urging force of the elastic member 104 (FIG. 15A). From this state, when the protruding portion 40 a of the platen shaft portion 40 is inserted into the bearing groove 46, the outer peripheral surface of the bearing 98 collides with the edge 96 of the engaging member 92, thereby causing the engaging member 92 to move to the elastic member 104. Against the urging force, it is rotated in a direction (clockwise in the figure) following the insertion operation of the protruding portion 40a (FIG. 15B). When the protruding portion 40a of the platen shaft portion 40 is continuously pushed into the bearing groove 46, the engaging member 92 is rotated counterclockwise in the figure by the biasing force of the elastic member 104 from the time when the predetermined insertion position is exceeded. Begin to. Then, when the bearing 98 reaches a position where it contacts the bottom edge of the bearing groove 46, the engaging member 92 returns to the initial position, and is brought into contact with the bearing 98 at the engaging point 100 as described above. The bearing 98 and the protruding portion 40a are anchored in the bearing groove 46 by the action of the stop region 102 (FIG. 15C).
[0075]
When the platen 18 is moved from the operating position to the non-operating position, the operator operates the operating portion 92a of the engaging member 92 so that the engaging member 92 is resisted against the biasing force of the elastic member 104 in the figure. Rotate in the direction. Thereby, the mutual engagement between the edge portion 96 of the engaging member 92 and the bearing 98 of the platen shaft portion 40 is released, so that the bearing 98 and the protruding portion 40a can be freely pulled out from the bearing groove 46.
[0076]
According to the thermal printer 90 having the above-described configuration, the engagement member 92 constituting the locking mechanism has a dimension represented by the distance between the rotation center 94 and the edge portion 96, and at least a required locking action. As long as it can be ensured to the extent that it can be exerted, the overall dimensions of the engaging member 92, particularly the distance between the pivot center 94 and the locking point 100, is significantly greater than that of the conventional engaging member made of a swinging hook. Can be reduced. Therefore, the engagement member 92 is not made of a rigid material such as reinforced metal, but is applied to the platen shaft portion 40 from the contact pressure applied to the platen 18 from the thermal head 12 or the power transmission mechanism 52 (FIG. 1). It can withstand external forces such as shear force. In this case, if the engaging member 92 is made from a resin material having excellent moldability, an increase in manufacturing cost of the thermal printer 90 can be suppressed.
[0077]
Thus, since the material rigidity of the engaging member 92 can be ignored to some extent, the engaging member 92 can be made of a material having excellent self-lubricating properties, for example. In this case, the bearing 98 of the platen shaft portion 40 can be omitted, and the protruding portion 40a can be directly anchored by the engaging member 92.
[0078]
【The invention's effect】
As is apparent from the above description, according to the present invention, in a thermal printer having a printable portion that can be opened and closed, there are inconveniences such as an increase in the number of parts, an increase in manufacturing cost, and a deterioration in paper supply / replacement workability. In addition, during the printing operation, the pair of support members can be fixedly locked in a closed state by the locking mechanism, so that the thermal head and the platen of the printing unit can be securely and stably held at the operating positions. become. Therefore, according to the present invention, a high-performance thermal printer capable of performing a stable printing operation is provided.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view of a thermal printer according to a first embodiment of the present invention when a printing unit is opened.
2 is a partial cross-sectional front view schematically showing a configuration of a locking mechanism in the thermal printer of FIG. 1;
FIGS. 3A and 3B are operation explanatory views of a locking mechanism in the thermal printer of FIG. 1, in which (a) a state immediately before the platen shaft is inserted into the bearing groove, (b) a state where the platen shaft is inserted into the bearing groove; (C) A state where the platen shaft is moored in the bearing groove.
4 is a schematic diagram showing a modification of the locking mechanism in the thermal printer of FIG.
FIGS. 5A and 5B are schematic views showing another modification of the locking mechanism in the thermal printer of FIG. 1, showing (a) a state before mooring and (b) a state during mooring.
FIG. 6 is a schematic view showing still another modification of the locking mechanism in the thermal printer of FIG.
FIG. 7 is a schematic view showing still another modification of the locking mechanism in the thermal printer of FIG. 1;
FIG. 8 is a schematic front view showing a configuration of a locking mechanism of a thermal printer according to a second embodiment of the present invention.
9 is a schematic view showing a modification of the locking mechanism of FIG.
10 is a schematic view showing another modification of the locking mechanism of FIG.
11 is a schematic view showing still another modification of the locking mechanism of FIG.
FIG. 12 is a schematic front view showing a configuration of a locking mechanism of a thermal printer according to a third embodiment of the present invention.
FIG. 13 is a schematic perspective view of a thermal printer according to a fourth embodiment of the present invention when a printing unit is opened.
14 is an enlarged front view schematically showing a configuration of a locking mechanism in the thermal printer of FIG. 13;
FIGS. 15A and 15B are operation explanatory views of the locking mechanism in the thermal printer of FIG. 13, (a) a state immediately before the platen shaft is inserted into the bearing groove; (b) a state where the platen shaft is inserted into the bearing groove; (C) A state where the platen shaft is moored in the bearing groove.
[Explanation of symbols]
12 ... Thermal head
14 ... 1st support member
16 ... 2nd support member
18 ... Platen
36 ... axis
40 ... Shaft
44. Bearing member
46 ... Bearing groove
48 ... receiving part
56, 66, 80, 104 ... elastic member
64, 76, 92 ... engaging member
94: Center of rotation
96 ... Rim
100 ... engagement point
102 ... Locking area

Claims (8)

サーマルヘッドと、該サーマルヘッドを支持する第１支持部材と、該第１支持部材に相対移動可能に組み合わされる第２支持部材と、該第２支持部材に支持され、該第１支持部材に対する該第２支持部材の移動に伴い、該サーマルヘッドと協働して印刷用紙を挟持する作用位置と該サーマルヘッドから離隔して印刷用紙を解放する非作用位置との間で変位するプラテンと、該プラテンを該作用位置に解除可能に係止する係止機構とを具備するサーマルプリンタにおいて、
前記係止機構は、
前記プラテンに回転軸線方向移動自在に連結される軸受部材と、
前記軸受部材を前記プラテンに対し回転軸線方向へ弾性的に付勢する弾性部材と、
前記第１支持部材に設けられ、前記プラテンが前記作用位置にあるときに、前記弾性部材の弾性的付勢力下で、前記軸受部材に脱離可能に係合して該軸受部材を予め定めた位置に固定的に保持するとともに、該軸受部材を介して該プラテンを回転自在に該作用位置に保持する保持部と、
を具備することを特徴とするサーマルプリンタ。A thermal head; a first support member that supports the thermal head; a second support member that is movably combined with the first support member; and a second support member that is supported by the second support member, and A platen that displaces between a working position for holding the printing paper in cooperation with the thermal head and a non-working position for releasing the printing paper away from the thermal head in association with the movement of the second support member; In a thermal printer comprising a locking mechanism for releasably locking the platen to the working position,
The locking mechanism is
A bearing member coupled to the platen so as to be freely movable in the rotational axis direction;
An elastic member for elastically urging the bearing member in the direction of the rotation axis with respect to the platen;
When the platen is provided in the first support member and the platen is in the working position, the bearing member is predetermined by being detachably engaged with the bearing member under an elastic biasing force of the elastic member. A holding portion that holds the platen in a fixed position at the working position while rotatably holding the platen via the bearing member;
A thermal printer comprising: 前記軸受部材は、回転軸線を中心とした錐体状輪郭を有する外輪部分を備え、前記保持部は、該外輪部分の該錐体状輪郭に適合する凹面輪郭を有する受容部分を備え、前記プラテンが前記作用位置にあるときに、該受容部分が該外輪部分を前記弾性的付勢力下で密接受容して静止保持する請求項１に記載のサーマルプリンタ。  The bearing member includes an outer ring portion having a cone-shaped contour with a rotation axis as a center, and the holding portion includes a receiving portion having a concave contour adapted to the cone-shaped contour of the outer ring portion, and the platen The thermal printer according to claim 1, wherein the receiving portion closely receives and holds the outer ring portion under the elastic biasing force when the lens is in the operating position. 前記プラテンが、筒状本体と該筒状本体の軸線方向両端面から軸線方向移動可能に同心状に突出する軸部とを備え、前記軸受部材は、該軸部の少なくとも一方の突出部分に装着されて、前記弾性部材の弾性的付勢力を受ける請求項１又は２に記載のサーマルプリンタ。  The platen includes a cylindrical main body and a shaft portion that protrudes concentrically so as to be axially movable from both axial end surfaces of the cylindrical main body, and the bearing member is attached to at least one protruding portion of the shaft portion. The thermal printer according to claim 1, wherein the thermal printer receives an elastic biasing force of the elastic member. サーマルヘッドと、該サーマルヘッドを支持する第１支持部材と、該第１支持部材に相対移動可能に組み合わされる第２支持部材と、該第２支持部材に支持され、該第１支持部材に対する該第２支持部材の移動に伴い、該サーマルヘッドと協働して印刷用紙を挟持する作用位置と該サーマルヘッドから離隔して印刷用紙を解放する非作用位置との間で変位するプラテンと、該プラテンを該作用位置に解除可能に係止する係止機構とを具備するサーマルプリンタにおいて、
前記係止機構は、
前記プラテンの前記作用位置と前記非作用位置との間の移動軌跡に沿って前記第１支持部材に設けられ、該プラテンが該作用位置にあるときに、該プラテンの軸部を回転自在に受容する軸受溝と、
前記第２支持部材に移動可能に取着され、前記第１支持部材に係合して、前記プラテンの前記軸部を前記軸受溝内に係留する係合部材とを具備し、
前記係合部材を前記第１支持部材から離脱させるために該係合部材に加える力の方向が、該係合部材が該第１支持部材から離脱した後に、前記プラテンを前記作用位置から前記非作用位置へ移動させるために該第２支持部材に加える力の方向と、実質的に同じであること、
を特徴とするサーマルプリンタ。A thermal head; a first support member that supports the thermal head; a second support member that is movably combined with the first support member; and a second support member that is supported by the second support member, and A platen that displaces between a working position for holding the printing paper in cooperation with the thermal head and a non-working position for releasing the printing paper away from the thermal head in association with the movement of the second support member; In a thermal printer comprising a locking mechanism for releasably locking the platen to the working position,
The locking mechanism is
The platen is provided on the first support member along a movement trajectory between the working position and the non-working position of the platen. When the platen is in the working position, the shaft of the platen is rotatably received. Bearing grooves to be
Said movably is attached to the second support member, engaged with the first support member, comprising an engaging member for anchoring the shaft portion of the platen to the bearing groove,
The direction of the force applied to the engagement member to disengage the engagement member from the first support member is such that the platen is moved away from the operating position after the engagement member is separated from the first support member. Substantially the same direction as the force applied to the second support member to move it to the working position;
A thermal printer characterized by サーマルヘッドと、該サーマルヘッドを支持する第１支持部材と、該第１支持部材に相対移動可能に組み合わされる第２支持部材と、該第２支持部材に支持され、該第１支持部材に対する該第２支持部材の移動に伴い、該サーマルヘッドと協働して印刷用紙を挟持する作用位置と該サーマルヘッドから離隔して印刷用紙を解放する非作用位置との間で変位するプラテンと、該プラテンを該作用位置に解除可能に係止する係止機構とを具備するサーマルプリンタにおいて、
前記係止機構は、
前記プラテンの前記作用位置と前記非作用位置との間の移動軌跡に沿って前記第１支持部材に設けられ、該プラテンが該作用位置にあるときに、該プラテンの軸部を回転自在に受容する軸受溝と、
前記第１支持部材に回動可能に取着され、前記作用位置にある前記プラテンにその回転を許容しつつ係合して、該プラテンの前記軸部を前記軸受溝内に係留する係合部材とを具備し、
前記係合部材は、前記第１支持部材上に位置する回動中心と、プラテン回転軸線方向に見て前記軸受溝の内側に突出可能な縁部とを有し、
前記係合部材の前記縁部は、前記作用位置にある前記プラテンに前記プラテン回転軸線方向に見て前記軸受溝の内側で係合する係合点を有するとともに、該係合点に隣接して、該係合部材の前記回動中心からの距離が該係合点よりも大きくなる係止領域を有し、該回動中心、該係合点及び該係止領域が、該プラテンを該作用位置に固定的に保持するような相対位置関係を有すること、
を特徴とするサーマルプリンタ。 A thermal head; a first support member that supports the thermal head; a second support member that is movably combined with the first support member; and a second support member that is supported by the second support member, and A platen that displaces between a working position for clamping the printing paper in cooperation with the thermal head and a non-working position for releasing the printing paper away from the thermal head in association with the movement of the second support member; In a thermal printer comprising a locking mechanism for releasably locking the platen to the working position,
The locking mechanism is
The platen is provided on the first support member along a movement trajectory between the working position and the non-working position of the platen. When the platen is in the working position, the shaft of the platen is rotatably received. Bearing grooves to be
An engagement member that is pivotally attached to the first support member and engages the platen in the working position while allowing its rotation, and anchors the shaft portion of the platen in the bearing groove. And
The engagement member has a rotation center located on the first support member, and an edge portion that can project inside the bearing groove when viewed in the platen rotation axis direction,
The edge portion of the engagement member has an engagement point that engages with the platen in the working position in the bearing groove when viewed in the platen rotation axis direction, and adjacent to the engagement point, The engaging member has a locking region in which the distance from the rotation center is larger than the engagement point, and the rotation center, the engagement point, and the locking region are fixed to the working position. Having a relative positional relationship such as
A thermal printer characterized by 前記係合部材を、前記縁部が前記プラテン回転軸線方向に見て前記軸受溝の内側に突出する方向へ弾性的に付勢する弾性部材をさらに具備する請求項５に記載のサーマルプリンタ。 The thermal printer according to claim 5, further comprising an elastic member that elastically biases the engaging member in a direction in which the edge portion protrudes inward of the bearing groove when viewed in the platen rotation axis direction . 前記プラテンを回転駆動する駆動機構が前記第１支持部材に設置され、該プラテンが前記作用位置にあるときに該プラテンが該駆動機構に作用的に連結されるとともに、該プラテンが前記非作用位置にあるときに該プラテンが該駆動機構から分離される請求項１〜６のいずれか１項に記載のサーマルプリンタ。 A drive mechanism for rotationally driving the platen is installed on the first support member. When the platen is in the operating position, the platen is operatively connected to the drive mechanism, and the platen is in the non-operating position. The thermal printer according to any one of claims 1 to 6, wherein the platen is separated from the drive mechanism when the printer is in the printer. 前記第２支持部材が前記第１支持部材に相対回動可能に組み合わされ、該第１支持部材に対する該第２支持部材の回動に伴い、前記プラテンが前記作用位置と前記非作用位置との間で変位する請求項１〜７のいずれか１項に記載のサーマルプリンタ。 The second support member is combined with the first support member so as to be relatively rotatable, and the platen moves between the operating position and the non-operating position as the second support member rotates relative to the first support member. The thermal printer of any one of Claims 1-7 displaced between .
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US8979407B2 (en) * 2007-08-08 2015-03-17 Zih Corp. Platen assembly
JP2010240881A (en) * 2009-04-01 2010-10-28 Fujitsu Component Ltd Thermal printer
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