JP4159850B2

JP4159850B2 - Chair with backrest

Info

Publication number: JP4159850B2
Application number: JP2002301760A
Authority: JP
Inventors: 本安都夫岡; 村英生西
Original assignee: Uchida Yoko Co Ltd
Current assignee: Uchida Yoko Co Ltd
Priority date: 2002-10-16
Filing date: 2002-10-16
Publication date: 2008-10-01
Anticipated expiration: 2022-10-16
Also published as: JP2004135769A

Description

【０００１】
【発明の属する技術分野】
本発明は椅子に係り、特にオフィスにおいて使用するに適する背もたれ付き椅子に関する。
【０００２】
【従来の技術】
近時オフィスにおいては、コンピュータ操作による執務が日常的となっている。このようなコンピュータ作業は、その性質上椅子に座っての執務姿勢が従来一般の事務作業に比べて異るものとなり、特に後傾姿勢での執務が多くなる。
【０００３】
ところで従来の事務用椅子は、座部に座って背もたれに体重を掛けることにより背もたれ全体が追従して後傾する構成であり、後傾姿勢による執務時には座る人の腰部から背部（胸椎部）にかけての全域が後傾する姿勢となる。
【０００４】
しかして従来一般の事務用椅子では、これに座して後傾姿勢によりコンピュータ作業を行うとき、身体の上半部全体が後方に傾いてしまうので身体の支持が不適切となり、特に背部の胸椎部の動きについての独立した追従ができないためかえって身体に負担が掛ってしまい、早期に疲れを覚え、長時間の執務に耐え得ることができなかった。
【０００５】
そこで背もたれの上半部を下半部に対し後傾させることができるようにした椅子として下記構成のものが提案されている。
【０００６】
すなわち、背もたれを上半部と下半部とに２分して横軸により枢支し、その上半部をバネ付勢に抗して下半部に対し後傾させることができるようになされたものがある（特許文献１参照）。
【０００７】
一方、背もたれの支点をその下方位置と上方位置との２点に分け、背もたれに寄り掛る態勢に応じて背もたれ全体の後傾姿勢がとられるようにした椅子がある（特許文献２参照）。
【０００８】
さらに背もたれの上方位置を支える中央の第１支持装置と、背もたれの下方位置の左右を支える第２支持装置とを共通の横軸で枢支し、背もたれの上方または下方に加わる荷重に応じて前記第１、第２支持装置が回動して座る人の後傾姿勢に追従するようになされたものがある（特許文献３参照）。
【０００９】
【特許文献１】
特開平２−５５００８号公報
【特許文献２】
特開平７−２８９３８４号公報
【特許文献３】
特表平９−５０３１４４号公報
【００１０】
【発明が解決しようとする課題】
しかる上記特許文献１に記載のものでは、背もたれの上半部のみが極端に後傾するので後傾姿勢をとるとき必ずしも背もたれが円滑に後傾せず、座り心地が今ひとつ十分でなく、また上記特許文献２に記載のものでは、背もたれ全体が背もたれ自体の弾性により後傾するので、寄り掛った際に不安定な感じを与え、楽な後傾姿勢を与えることができないという問題がある。
【００１１】
さらに上記特許文献３に記載のものでは、背もたれに偏心した荷重が加わった際に第２支持装置が左右独立して回動することになってぎくしゃくした動きとなり、座り心地が必ずしもよくないという問題点があるうえ、背もたれの上方部は第１支持装置の上端の１点で支持しているので、後傾時における背もたれの上方部の安定性に欠け、さらに第１、第２支持装置の支柱は合計３本を必要としているので、部品点数が多く、コスト的に不利であるとともに耐久性、メンテナンス性に劣るなどの問題点がある。
【００１２】
本発明はこれらに鑑み、背もたれに寄り掛って後傾姿勢をとるとき人体の胸椎部をフレキシブルに柔軟に後傾させることができ、後傾姿勢による執務をスムースに行えるようにすること、および少ない部品点数により安価に提供することを課題としてなされたものである。
【００１３】
【課題を解決するための手段】
上記課題を解決する手段として本発明は、脚により支持される受台上に座部を有するとともに該受台に側面視略Ｌ形状を有する背フレームの前部端を上下方向揺動可能に枢支し、この背フレームに背もたれを支持してなる背もたれ付きの椅子において、前記背フレームの後部立上げ部の上部位置に背支柱を弾性的に後傾動自在に設け、この背支柱はその上端部両側に左右方向に延びる背アームを有し、これら背アームの先端を前記背もたれの上方部背面左右位置に係着させ、前記背アームを含む背支柱を介して背もたれの上方部が後傾するようにしたことを特徴とする。
【００１４】
こうしたことにより、背もたれに寄り掛ったとき背フレームの後傾回動により背もたれ全体が後傾し、かつ背もたれの上方部は背フレームの立上げ部の上端から立ち上がる背支柱の後傾動、および背アームの撓みにより無理なく身体の動きに追従して後傾し、安定した後傾姿勢をとることができる。
【００１５】
請求項２記載の発明は、前記立上げ部の上部位置に前記背もたれの人体腰部に対応する部位の背面に当る腰部当接部を設けたことにある。
【００１６】
請求項３記載の発明は、前記背支柱の下端前部を前記背もたれの人体腰部が当接する位置の背面中央部に軸により後傾動自在に枢支するとともに、前記背フレームの立上げ部に圧縮バネを内蔵し、この圧縮バネの上端に前記背支柱の枢軸より後部位置のバネ受部を当接させ、この圧縮バネにより背支柱を起立方向に付勢したことにある。
【００１７】
請求項４記載の発明は、前記圧縮バネの軸線の上端側を前記枢軸に対し離接する方向複数箇所に位置変更可能に形成し、圧縮バネの反力を選択可能としたことにある。
【００１８】
請求項５記載の発明は、前記背支柱の下端を前記背フレームの立上げ部の上端に軸により後傾動自在に枢支するとともに前記立上げ部に圧縮バネを内蔵し、この圧縮バネの下端に結合したワイヤの上端を前記背支柱の枢軸より斜め前下方へ向け延設されたワイヤ係合部の複数箇所に選択的に係合自在に形成し、このワイヤの上端の係合位置を変更することにより圧縮バネの反力を選択可能としたことにある。
【００１９】
請求項６記載の発明は、前記背フレームの立上げ部の上端前部に、前記背もたれの人体腰部が当る部位に向けて突出する腰部当接部を突設したことにある。
【００２０】
請求項７記載の発明は、前記背支柱を、前記背フレームの立上げ部の上端に軸により後傾動自在に枢支するとともに、該枢軸より下位の背支柱下端と前記背もたれとの間に圧縮バネを介装し、前記背支柱の背アームの先端を前記背もたれの背面に上下方向可動に係着したことにある。
【００２１】
請求項８記載の発明は、前記背支柱の下端前部を前記背もたれの人体腰部が当接する部位の背面中央部に軸により後傾動自在に枢支し、前記背フレームの上端に弾性体受部を設け、この弾性体受部内にゴム等の弾性体を配設し、この弾性体に前記背支柱の下端に垂設された押圧部を当接させ、前記弾性体の復元力により背支柱を起立方向に付勢したことにある。
【００２２】
請求項９記載の発明は、前記背支柱と前記背フレームの立上げ部とを弾性を有する樹脂により一体に形成し、これら背支柱と立上げ部とは前記背もたれの人体腰部が当接する部位の背部位置に伸展方向に弾性を有する屈曲部を設け、この屈曲部の突端を腰部当接部としたことにある。
【００２３】
請求項１０記載の発明は、前記背支柱と前記背フレームの立上げ部とを弾性を有する樹脂により形成し、前記立上げ部の上方前部に背もたれの人体腰部が当接する部位の背面に当る腰部当接部を突設し、この腰部当接部より上方位置に伸展方向に弾性を有する屈曲部を設けたことにある。
【００２４】
いずれにおいても、圧縮バネ（弾性体）のクッション性により、背もたれの後傾動時の感触がよいとともに、背支柱の上端両側に延びる背アームにより背もたれの上半部（胸椎部位）の捩れに追従するので使用者に無理なくなじみ、また腰部当接部を設けることにより、人体の腰部の当たりを柔げて後傾動時における人体腰部の感触をよくすることができ、これらの総合により座り心地がよく、執務を楽な姿勢で行うことができる。
【００２５】
【発明の実施の形態】
以下、本発明を図面に示す実施の形態を参照して説明する。
【００２６】
図１は本発明による背もたれ付き椅子の基本的実施形態の一部を断面とした側面図を示し、図２は図１の脚を図示省略した背面図を、図３は同平面図を示している。
【００２７】
上記背もたれ付き椅子の基本構成は、キャスタ付きの脚１に支持された支柱２に回転自在に支持され上部に座部３を有する受台４と、この受台４に後傾動自在に枢支された背フレーム５と、背もたれ６とを具備している。
【００２８】
前記背フレーム５は、側面視略Ｌ形状を有し、この背フレーム５の前端近くが前記受台４の前部寄りの下部に軸７により後傾動自在に枢支され、背フレーム５の後部の立上げ部８は背もたれ６の背面幅方向中央に位置してその上端は背もたれ６の人体腰部が当る腰部位置ａまで立ち上げられている。
【００２９】
前記背フレーム５の立上げ部８の上方位置には背支柱９が設けられている。
【００３０】
この背支柱９は、アルミ材等の剛性を有する資材からなっており、前記背もたれ６の前記腰部位置ａの背後に位置する前記立上げ部８の上端から前方へ向け延びる腰部当接部１０に前記背支柱９の下端から前方へ延びる取付部９ａの先端が軸１１により後方へ回動可能に枢支されている。
【００３１】
上記背支柱９の上端の左右部には、図２、図３にみられるように略水平方向に左右の背アーム１２，１２が左右対称に延設されており、これら背アーム１２，１２の先端は背もたれ６の背板１３の上方位置（胸椎部相当位置）の左右部に若干の動きを許容し得るように係着されている。この係着手段としては、背アーム１２，１２の先端に突設したピン（図示省略）を背もたれ６の背板１３に埋設されたゴム等の弾性体からなるピン受１４，１４に挿着し、この弾性体の変形により動きを許容するようにすることができる。なおこの係着手段は背アーム１２，１２の若干の動きを許容し得れば他の手段であってもよい。
【００３２】
前記背フレーム５の立上げ部８は中空構造とされており、この立上げ部８内に圧縮バネ１５が内装されている。この圧縮バネ１５は、背フレーム５の下面側から立上げ部８内に挿通されたバネ圧調整軸１６の内端のバネ座１７と摺動用部材１８との間に介装され、この摺動用部材１８の半球面状を有する先端部が前記背支柱９の前記軸１１より後部側に設けられた下向きのバネ受部１９に圧接されている。
【００３３】
したがって背支柱９が後傾動するとき前記バネ受部１９を介して圧縮バネ１５を撓ませることで背もたれ６の腰部位置ａより上方部の後傾時のクッション性が与えられる。そして前記バネ圧調整軸１６の下端のつまみ２０を回動することにより前記バネ座１７をネジ（図示省略）により進退させることができるようになっており、このバネ座１７の位置を選択することによって前記のクッション性を最適に設定することができる。
【００３４】
前記背もたれ６の背板１３は、図２にみられるように前記腰部位置ａにおいて横方向に長い打ち抜き孔２１が形成されており、その孔２１の両側の部分１３ａ，１３ａで背もたれ６の上方部の後傾時に曲がりやすくされている。
【００３５】
図１、図２において符号２２は前記打ち抜き孔２１の部分を被覆する化粧板、２３は背フレーム５の後傾時における負荷値を調整すべく周知のバネ（図示せず）のバネ圧調整用つまみである。
【００３６】
次に上記実施形態の作用を説明する。
【００３７】
背もたれ付き椅子に座らない不使用時には、図１に示すように圧縮バネ１５による付勢により圧縮バネ１５の上端の摺動用部材１８の上端が背支柱９のバネ受部１９を押し上げるので背支柱９は起立方向へ付勢され、これにより背もたれ６が起立姿勢におかれる。
【００３８】
背もたれ付き椅子に座り、背中を背もたれ６に寄り掛って体重を掛けると、通常では背フレーム５が軸７を支点に後傾回動して背もたれ６全体が後傾し、リクライニング姿勢をとることができる。
【００３９】
上記姿勢からさらに背もたれ６に寄り掛って安楽姿勢をとると、人体の腰部が当る部分（腰部位置ａ）は立上げ部８の腰部当接部１０により支えられ、それより上方の背もたれ６の上半部が背支柱９の枢軸１１を支点として後傾し、その背支柱９のバネ受部１９が圧縮バネ１５を撓ませながら後傾する。このときバネ受部１９は圧縮バネ１５の上端の摺動用部材１８に対し摺動して背支柱９の後傾動を許容する。
【００４０】
上記背もたれ６の上半部の後傾具合いに関しては、つまみ２０を回動してバネ座１７の位置を変え、圧縮バネ１５の弾発力を調整することにより使用者の好みに合う状態に設定することができる。
【００４１】
上記のような安楽姿勢をとって執務するとき、人体の腰が当る部分は腰部当接部１０によって撓みが規制されるので不自然な体形になることがなく、また胸椎部分は背支柱９の左右の背アーム１２，１２によって支えられるので背もたれ６の上半部の左右への捩れを許容しつつ後傾し、最も楽な姿勢を保つことができる。加えて肩甲骨部位も左右の背アーム１２，１２のそれぞれの撓みにより微妙な身体の動きに背もたれ６の上半部が追従するので疲れを感じさせることがない。
【００４２】
図４は上記実施形態の変形例を示すもので、圧縮バネ１５の上部中心に挿通するロッド２４のバネ座２４ａと、立上げ部８の軸受部２５に揺動可能に支持されたバネ座２６の間に圧縮バネ１５が介装されている。
【００４３】
そして上記ロッド２４の上端は、図４（Ｂ）に拡大して示すように、背支柱９の下端の前方に向けて屈曲した形態の取付部９ａに上下に貫通した長孔９ｂに挿通されてその上部に突出されており、前記バネ座２６の上面に突設された凸部２４ｂが前記取付部９ａの長孔９ｂの長さの範囲内の下面に列設された複数の凹部２７，２７…の一つに係合させることができるようになっている。２８はその係合位置を変える際の操作用つまみを示す。
【００４４】
図４において図１〜図３と共通する部材にはこれと同一符号を付すに留め、詳細な説明は省略する。
【００４５】
この実施形態によれば圧縮バネ１５の作用点が背支柱９の後傾時に支点となる枢軸１１からの距離により変化するので、前記凹部２７，２７…を選択することにより安楽姿勢時における背もたれ６の上半部のクッション性を最適な状態に設定することができる。
【００４６】
図５はさらに他の変形例を示すもので、背支柱９の下端部が立上げ部８の上端位置に軸１１により後傾動自在に枢支され、この背支柱９の枢軸１１より下方に斜め前下方へ向け延長されたワイヤ係合部９ｃが形成されており、このワイヤ係合部９ｃの上面には複数の凹部２９，２９…が列設されている。
【００４７】
一方、立上げ部８に内装される圧縮バネ１５の下端を支える上下動が可能なバネ受３０にワイヤ３１の下端が結着され、このワイヤ３１は図５（Ｂ）に拡大して示すように前記ワイヤ係合部９ｃの凹部２９，２９…が設けられる範囲に形成された長孔９ｄに挿通され、ワイヤ３１の上端に固着された係合片３２が前記凹部２９，２９…の一つの選択的に係合させることができるようになっている。そして上記ワイヤ３１の途中部は、立上げ部８に固設のピン３３の側面を経由し、前記係合片３２をいずれの凹部２９，２９…に係合させてもピン３３より下方のワイヤ３１の位置が変動しないようになされている。
【００４８】
この実施形態においては、腰部当接部１０は立上げ部８の上端前側に一体に設けた部材により構成されている。
【００４９】
この実施形態によれば、ワイヤ３１の係合片３２を背支柱９の枢軸１１から離れた位置の凹部２９に係合させれば軸１１から作用点の距離が長くなるとともに圧縮バネ１５の圧縮量も多くなるので、背もたれ６の上半部の後傾動時のクッション性が堅くなり、逆に枢軸１１に近い位置の凹部２９に係合片３２を係合させれば作用点の距離が短くなるとともに圧縮バネ１５の圧縮量も少なくなり、背もたれ６の上半部のクッション性が柔らかくなる。
【００５０】
したがって係合片３２を引っ張っていずれかの凹部２９，２９…に嵌め替えるだけで最適な安楽姿勢をとれるようにすることができる。
【００５１】
図６〜図８は本発明の他の実施形態を示すもので、図６（Ａ）は側面図、同（Ｂ）は背面図、図７は作用を示している。
【００５２】
上記背フレーム５の立上げ部８の上端には背支柱９の下端が軸１１により後方へ回動を許容するように枢支されており、この背支柱９の上端の左右部には弾性を有する資材からなる左右の背アーム１２，１２が左右対称に延設され、これら背アーム１２，１２の先端は背もたれ６の背板１３の上方位置（胸椎部相当位置）の左右部に上下方向摺動可能に係合されている。
【００５３】
前記背フレーム５の立上げ部８の上端位置には腰部当接部１０が設けられ、この腰部当接部１０は背もたれ５の腰部位置ａの背面に当接されている。この腰部当接部１０は、ゴム、発泡樹脂等の弾性体を介して背もたれ５の腰部位置ａの背面に弾性的に当接するようにすることが後傾姿勢をとる際の当りを柔げるうえで好ましい。
【００５４】
前記背支柱９の下端は図８に示すように前記背フレーム５の立上げ部８の内側に延在され、この延在する延長部９ｅと腰部当接部１０との間に圧縮バネ３４が介装されており、前記腰部当接部１０から延長部９ｅ、立上げ部８を貫通する調整ネジ３５のつまみ３６を回動することにより圧縮バネ３４の撓み量を加減して背支柱９の後傾動時の負荷値を調整可能とされている。
【００５５】
前記背もたれ６は、樹脂成形品からなる背板１３と、この背板１３に添設されるクッションとで構成されるが、前記背板１３の前記腰部位置ａ相当の位置から胸椎部ｂ相当の位置までの所要範囲に横方向にスリット３７，３７…が複数条設けられ、このスリット３７，３７…が設けられている範囲において背もたれ６が後方へ屈曲可能とされている。
【００５６】
前記背支柱９の背アーム１２，１２の先端と背もたれ６の背板１３との摺動係合に関しては、図示の例では背もたれ６の背面左右端近くに設けられた縦方向の長孔３８，３８と、前記背アーム１２，１２の先端に設けられたスライダ３９，３９との係合により上下方向にスライド自在とされている。しかしこの摺動係合については必ずしも長孔３８とスライダ３９とによらず、背アーム１２，１２の先端にシューを設けて背もたれ６の背面に弾性的に当接させることにより摺動するようにしてもよい。
【００５７】
他の図１〜図３と共通する部材にはこれと同一符号を付すに留め、詳細な説明は省略する。
【００５８】
次に上記実施形態の作用を説明する。
【００５９】
背もたれ付き椅子に座らない不使用時には図６（Ａ）、図８（Ａ）に示すように背フレーム５の内蔵バネの作用を受けて軸７を支点に図６（Ａ）において反時計方向に回動した状態におかれ、また背支柱９は圧縮バネ３４の付勢により直立状態におかれている。
【００６０】
背もたれ付き椅子に座り、背中を背もたれ６に寄り掛って体重を掛けると、通常では背フレーム５が後傾回動して背もたれ６全体が図７に実線で示すように後傾し、リクライニング姿勢をとることができる。
【００６１】
上記姿勢からさらに背もたれ６に寄り掛って安楽姿勢をとると、人体の腰部が当る部分（腰部位置ａ）は腰部当接部１０により支えられ、背もたれ６の上半部が背支柱９を軸１１を中心に圧縮バネ３４の付勢に抗して後傾することにより図７に符号Ｒで示すように後傾する。この背もたれ６の上半部の後傾動に際しては、背アーム１２，１２の先端のスライダ３９，３９と背もたれ６の長孔３８，３８との摺動によって後傾動が許容される。
【００６２】
また背もたれ６の上方部の左右への撚れが加わったときは、背アーム１２，１２が撓むことにより許容される。
【００６３】
上記の背もたれ６の上半部の後傾具合いに関しては、つまみ３６を回動して圧縮バネ３４の弾力を調整することにより使用者の好みに合う状態に設定することができる。
【００６４】
このように安楽姿勢をとって執務するとき、人体の腰の部分は背もたれ６が撓まず、腰部当接部１０により固定されるので不自然な体形になることがなく、胸椎部位ｂは自由に後傾するので最も楽な姿勢を保つことができる。また肩甲骨部位は左右の背アーム１２，１２のそれぞれの撓みにより微妙な身体の動きに背もたれ６の上半部が追従するので疲れを感じさせることがない。
【００６５】
図９は本発明のさらに他の実施形態を示すもので、背支柱９の下端から前方へ向け屈曲されて延長された取付部９ａの先端が立上げ部８の前方へ向け屈曲されて腰部当接部１０となる部分に軸１１により後傾動自在に枢支されている。
【００６６】
上記背支柱９の枢軸１１より後方位置の下部に押圧部４０が垂設されており、また立上げ部８の腰部当接部１０の上面には凹陥状の弾性体受部４１が設けられていて、この弾性体受部４１内にゴム等の弾性体４２が固着され、この弾性体４２の後部面に背支柱９の前記押圧部４０が当接するように構成されている。
【００６７】
したがって背もたれ６の上半部を後傾させたとき背支柱９が枢軸１１を支点として後傾回動し、そのとき背支柱９の押圧部４０が弾性体４２を押圧して変形させることによりクッション性が与えられる。
【００６８】
図１０は図９に示した実施形態における背支柱９の押圧部４０を水平に近い形態とし、背支柱９の後傾回動時に弾性体４２が上方から押されるようにしたものである。
【００６９】
さらに図１１は、弾性体受部４１を立上げ部８の上端内部に設け、背支柱９の押圧部４０を垂直に近い形態として、背面側から弾性体４２が押圧されるようになされたものである。
【００７０】
これら図９〜図１１において、図１〜図３と共通する部材にはこれと同一符号を付すに留め、詳細な説明は省略する。
【００７１】
図１２、図１３は、背フレーム５の立上げ部８と背支柱９とに弾性に富む樹脂により一体に形成したもので、図１２では背もたれ６の腰部位置ａで前方に向け突出するようにＶ形に屈曲させ、その屈曲部４３の先端が腰部当接部を構成するようになっており、またその屈曲部４３の弾性により背もたれ６の上半部のクッション性が与えられるようになされている。
【００７２】
図１３では屈曲部４３を腰部位置ａより上方の位置に設け、腰部位置ａに立上げ部８から前方に向け突設された腰部当接部１０が位置するようになされている。
【００７３】
これら図１２、図１３においては、前記図１〜図３と共通する部材にこれと同一符号を付すに留める。
【００７４】
【発明の効果】
以上説明したように本発明によれば、背もたれに寄り掛ったとき背フレームの後傾回動により背もたれ全体が後傾し、かつ背もたれの上方部は背フレームの立上げ部の上端から立ち上がる背支柱の後傾動および背アームの撓みにより無理なく身体の動きに追従して後傾し、安定した安楽姿勢をとることができる。
【００７５】
背もたれの腰部位置を背フレームの立上げ部上端の腰部当接部で支えるようにすれば、背もたれ全体が後傾してしまうことがなく、よく身体にフィットして楽な形で後傾姿勢をとることができる。
【図面の簡単な説明】
【図１】本発明による背もたれ付き椅子の一実施形態を示す一部を断面とした側面図。
【図２】同、脚を除去した背面図。
【図３】同、平面図。
【図４】図１の変形例を示し、（Ａ）は図１相当図、（Ｂ）は要部の拡大図。
【図５】図１のさらに他の変形例を示し、（Ａ）は図１相当図、（Ｂ）は要部の拡大図。
【図６】本発明の他の実施形態を示し、（Ａ）は側面図、（Ｂ）は背面図。
【図７】同、作用を示す説明図。
【図８】（Ａ）、（Ｂ）は図７の要部の作用を示す断面図。
【図９】本発明の他の実施形態を示す側面図。
【図１０】図９の変形例を示す側面図。
【図１１】図９のさらに他の変形例を示す側面図。
【図１２】本発明の他の実施形態を示す側面図。
【図１３】図１２の変形例を示す側面図。
【符号の説明】
３座部
４受台
５背フレーム
６背もたれ
８立上げ部
９背支柱
１０腰部当接部
１２背フレーム
１３背板
１５圧縮バネ
１６バネ圧調整軸
１８摺動用部材
１９バネ受部
２４ロッド
２６凸部
２７，２９凹部
３１ワイヤ
３２係合片
３３ピン
３４圧縮バネ
３８長孔
３９スライダ
４０押圧部
４１弾性体受部
４２弾性体
４３屈曲部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a chair, and more particularly to a chair with a backrest suitable for use in an office.
[0002]
[Prior art]
In recent offices, computer-based work has become a daily routine. Due to the nature of such computer work, the working posture of sitting on a chair is different from that of conventional office work, and in particular, the working posture in a tilted posture is increased.
[0003]
By the way, the conventional office chair has a structure in which the entire backrest follows and leans backward by sitting on the seat and putting the weight on the backrest. From the back of the seated person to the back (thoracic vertebrae) when working in a tilted position The whole area is inclined backward.
[0004]
Thus, in a conventional office chair, when sitting on this computer and performing computer work in a backward tilted posture, the entire upper half of the body tilts backward, making the body unsuitable, especially the thoracic spine at the back. The body could not be tracked independently because of the inability to follow the movements of the clubs. Instead, they were tired early and could not withstand long hours of work.
[0005]
Therefore, chairs having the following configurations have been proposed as chairs that allow the upper half of the backrest to be tilted backward with respect to the lower half.
[0006]
That is, the backrest is divided into the upper half and the lower half and pivotally supported by the horizontal axis, and the upper half can be tilted backward with respect to the lower half against the spring bias. (See Patent Document 1).
[0007]
On the other hand, there is a chair in which the fulcrum of the backrest is divided into two points, a lower position and an upper position, so that the backrest posture of the entire backrest can be taken according to the posture leaning on the backrest (see Patent Document 2).
[0008]
Further, a central first support device that supports the upper position of the backrest and a second support device that supports the left and right positions of the lower position of the backrest are pivotally supported by a common horizontal axis, and the above-mentioned is applied according to the load applied above or below the backrest. There is one in which the first and second support devices are configured to follow a backward tilt posture of a person sitting by turning (see Patent Document 3).
[0009]
[Patent Document 1]
JP-A-2-55008 [Patent Document 2]
JP-A-7-289384 [Patent Document 3]
Japanese Patent Publication No. 9-503144
[Problems to be solved by the invention]
However, in the thing of the said patent document 1, since only the upper half part of a backrest leans back extremely, when taking a back leaning posture, the backrest does not necessarily tilt backward smoothly, and the sitting comfort is not enough one more time, and the above-mentioned In the thing of patent document 2, since the whole backrest inclines backward by the elasticity of the backrest itself, when it leans, there exists a problem that an unstable feeling is given and an easy back leaning posture cannot be given.
[0011]
Furthermore, in the thing of the said patent document 3, when the eccentric load is applied to the backrest, it becomes a jerky movement because the second support device rotates independently from the left and right, and the sitting comfort is not necessarily good. In addition, since the upper part of the backrest is supported by one point on the upper end of the first support device, the upper part of the backrest is not stable when tilted backward, and the support columns of the first and second support devices Requires a total of three, and thus has a large number of parts, which is disadvantageous in terms of cost and inferior in durability and maintainability.
[0012]
In view of the above, the present invention can flexibly and flexibly tilt the thoracic vertebrae of the human body when leaning back and leaning back, and can smoothly perform work in the leaning posture, and less The problem is to provide a low cost by the number of parts.
[0013]
[Means for Solving the Problems]
As a means for solving the above-mentioned problems, the present invention provides a seat portion on a pedestal supported by legs and a front frame end having a substantially L shape in a side view on the pedestal. In a chair with a backrest that supports the backrest on the back frame, a back strut is provided elastically at the upper position of the rear raised portion of the back frame so that the back strut can be tilted backward, and the back strut has an upper end portion. There are back arms extending in the left and right directions on both sides, and the tips of these back arms are engaged with the left and right positions on the back of the upper part of the backrest so that the upper part of the backrest tilts backward via the back strut including the back arm. It is characterized by that.
[0014]
As a result, when leaning against the backrest, the entire backrest is tilted backward by the backward rotation of the back frame, and the upper part of the backrest is tilted backward from the upper end of the rising portion of the back frame, and the back arm It is possible to take a stable backward leaning posture by following the movement of the body without difficulty by bending of the body.
[0015]
According to a second aspect of the present invention, there is provided a waist contact portion that hits the back of a portion corresponding to the human waist of the backrest at an upper position of the rising portion.
[0016]
According to a third aspect of the present invention, the front end of the lower end of the back column is pivotally supported by a shaft at the center of the back of the position where the human waist of the back rests, and is compressed to the rising portion of the back frame. A spring is incorporated, and a spring receiving portion at a rear position from the pivot of the back strut is brought into contact with the upper end of the compression spring, and the back strut is urged in the standing direction by the compression spring.
[0017]
According to a fourth aspect of the present invention, the upper end side of the axis of the compression spring is formed so as to be changeable in a plurality of locations in the direction of separating from and contacting the pivot, and the reaction force of the compression spring can be selected.
[0018]
According to a fifth aspect of the present invention, the lower end of the back column is pivotally supported by the shaft at the upper end of the rising portion of the back frame so as to be tiltable rearwardly, and a compression spring is built in the rising portion, and the lower end of the compression spring The upper end of the wire coupled to the back strut is formed to be selectively engageable at a plurality of positions of the wire engaging portion extending obliquely forward and downward from the pivot axis of the back column, and the engagement position of the upper end of the wire is changed. Thus, the reaction force of the compression spring can be selected.
[0019]
The invention according to claim 6 is that a waist contact portion projecting toward a portion where the human waist portion of the backrest hits is provided at a front upper end portion of the rising portion of the back frame.
[0020]
According to a seventh aspect of the present invention, the back strut is pivotally supported by the shaft at the upper end of the rising portion of the back frame so as to be tiltable rearwardly, and compressed between the lower end of the back strut lower than the pivot and the backrest. A spring is interposed, and the tip of the back arm of the back column is engaged with the back of the backrest so as to be movable in the vertical direction.
[0021]
The invention according to claim 8 is characterized in that the lower end front portion of the back column is pivotally supported by a shaft at the center of the back surface of the portion where the human waist of the backrest abuts, and an elastic body receiving portion is provided at the upper end of the back frame. An elastic body such as rubber is disposed in the elastic body receiving portion, a pressing portion suspended from the lower end of the back strut is brought into contact with the elastic body, and the back strut is supported by the restoring force of the elastic body. It is because of energizing in the standing direction.
[0022]
According to a ninth aspect of the present invention, the back strut and the rising portion of the back frame are integrally formed of a resin having elasticity, and the back strut and the rising portion are parts of the portion where the human waist portion of the backrest comes into contact. A bent portion having elasticity in the extending direction is provided at the back position, and a protruding end of the bent portion is used as a waist contact portion.
[0023]
According to a tenth aspect of the present invention, the back strut and the raised portion of the back frame are formed of an elastic resin, and the back of the portion where the human back of the back is in contact with the upper front portion of the raised portion. A waist contact portion is provided in a protruding manner, and a bent portion having elasticity in the extending direction is provided at a position above the waist contact portion.
[0024]
In any case, the cushioning property of the compression spring (elastic body) provides a good feel when the backrest is tilted, and the back arms extending on both sides of the upper end of the back column follow the torsion of the upper half of the back (thoracic vertebra part). Therefore, it is comfortable to the user, and by providing a waist contact part, it is possible to soften the contact of the waist of the human body and improve the feel of the human waist when tilting backwards. , Work can be done in an easy attitude.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to embodiments shown in the drawings.
[0026]
FIG. 1 is a side view showing a cross-section of a basic embodiment of a chair with a backrest according to the present invention, FIG. 2 is a rear view with the legs of FIG. 1 omitted, and FIG. 3 is a plan view thereof. Yes.
[0027]
The basic structure of the chair with a backrest is supported by a support column 2 supported by a leg 1 with a caster and is rotatably supported by a support base 4 having a seat portion 3 on the upper part thereof. A back frame 5 and a backrest 6 are provided.
[0028]
The back frame 5 has a substantially L shape in a side view, and a portion near the front end of the back frame 5 is pivotally supported by a shaft 7 at a lower portion near the front portion of the cradle 4 so as to be tiltable rearward. The upright portion 8 is located at the center of the backrest 6 in the width direction of the back surface, and the upper end of the upright portion 8 is raised to the waist position a where the human waist of the backrest 6 hits.
[0029]
A back column 9 is provided above the raised portion 8 of the back frame 5.
[0030]
The back strut 9 is made of a material having rigidity such as an aluminum material, and is formed on a waist contact portion 10 that extends forward from the upper end of the rising portion 8 located behind the waist position a of the backrest 6. A tip of a mounting portion 9a extending forward from the lower end of the back column 9 is pivotally supported by a shaft 11 so as to be pivotable backward.
[0031]
As shown in FIGS. 2 and 3, left and right back arms 12, 12 extend symmetrically in a substantially horizontal direction on the left and right portions of the upper end of the back strut 9. The distal end is engaged with the left and right portions of the back plate 13 of the backrest 6 above the back plate 13 (position corresponding to the thoracic vertebra) so as to allow slight movement. As this engaging means, a pin (not shown) protruding from the tip of the back arm 12, 12 is inserted into a pin receiver 14, 14 made of an elastic body such as rubber embedded in the back plate 13 of the backrest 6. The movement of the elastic body can be allowed. The engaging means may be other means as long as it allows a slight movement of the back arms 12 and 12.
[0032]
The rising portion 8 of the back frame 5 has a hollow structure, and a compression spring 15 is housed in the rising portion 8. The compression spring 15 is interposed between a spring seat 17 at the inner end of the spring pressure adjusting shaft 16 inserted into the rising portion 8 from the lower surface side of the back frame 5 and a sliding member 18. A tip end portion of the member 18 having a hemispherical shape is pressed against a downward spring receiving portion 19 provided on the rear side of the shaft 11 of the back column 9.
[0033]
Therefore, when the back column 9 tilts backward, the compression spring 15 is bent through the spring receiving portion 19 to provide cushioning when the backrest 6 is tilted backward from the waist position a of the backrest 6. The spring seat 17 can be moved forward and backward by a screw (not shown) by turning the knob 20 at the lower end of the spring pressure adjusting shaft 16, and the position of the spring seat 17 is selected. Thus, the cushioning property can be set optimally.
[0034]
As shown in FIG. 2, the back plate 13 of the backrest 6 has a laterally long punching hole 21 at the waist position a, and the upper portion of the backrest 6 is formed by portions 13a and 13a on both sides of the hole 21. It is easy to bend when leaning backward.
[0035]
1 and 2, reference numeral 22 is a decorative plate covering the punched hole 21, and 23 is a spring pressure adjustment of a known spring (not shown) for adjusting the load value when the back frame 5 is tilted backward. It is a knob.
[0036]
Next, the operation of the above embodiment will be described.
[0037]
When not sitting on a chair with a backrest, as shown in FIG. 1, the upper end of the sliding member 18 at the upper end of the compression spring 15 pushes up the spring receiving portion 19 of the back column 9 by urging by the compression spring 15. Is urged in the standing direction, whereby the backrest 6 is placed in a standing posture.
[0038]
When sitting on a chair with a backrest and leaning back against the backrest 6, the back frame 5 usually rotates backward with the shaft 7 as a fulcrum so that the entire backrest 6 tilts backward and takes a reclining posture. it can.
[0039]
When the user leans further on the backrest 6 from the above posture and takes a comfortable posture, the portion of the human body that touches the waist (the waist position a) is supported by the waist contact portion 10 of the rising portion 8 and the backrest 6 above the backrest 6 The half part tilts backward with the pivot 11 of the back column 9 as a fulcrum, and the spring receiving part 19 of the back column 9 tilts backward while bending the compression spring 15. At this time, the spring receiving portion 19 slides with respect to the sliding member 18 at the upper end of the compression spring 15 and allows the back column 9 to tilt backward.
[0040]
As for the back tilt of the upper half of the backrest 6, the knob 20 is rotated to change the position of the spring seat 17, and the elastic force of the compression spring 15 is adjusted so as to suit the user's preference. can do.
[0041]
When working in the above-described comfort posture, the portion of the human body that touches the waist does not become an unnatural body shape because the flexure is restricted by the lumbar abutment portion 10, and the thoracic vertebra portion does not have the back strut 9. Since it is supported by the left and right back arms 12 and 12, the upper half of the backrest 6 tilts backward while allowing torsion to the left and right, and the most comfortable posture can be maintained. In addition, since the upper half of the backrest 6 follows subtle body movements due to the flexure of the left and right back arms 12, 12, the scapula site does not feel tired.
[0042]
FIG. 4 shows a modification of the above-described embodiment. The spring seat 24 a of the rod 24 inserted through the upper center of the compression spring 15 and the spring seat 26 supported so as to be swingable by the bearing portion 25 of the rising portion 8. A compression spring 15 is interposed therebetween.
[0043]
4B, the upper end of the rod 24 is inserted into a long hole 9b that vertically penetrates the mounting portion 9a that is bent toward the front of the lower end of the back column 9. As shown in FIG. A plurality of recesses 27, 27 projecting from the upper portion and projecting from the upper surface of the spring seat 26 are arranged on the lower surface within the length of the long hole 9b of the mounting portion 9a. It can be engaged with one of ... Reference numeral 28 denotes an operation knob for changing the engagement position.
[0044]
In FIG. 4, members common to FIGS. 1 to 3 are given the same reference numerals, and detailed description thereof is omitted.
[0045]
According to this embodiment, since the point of action of the compression spring 15 changes depending on the distance from the pivot 11 serving as a fulcrum when the back column 9 is tilted backward, the backrest 6 in the comfort posture is selected by selecting the recesses 27, 27. The cushioning property of the upper half can be set to an optimum state.
[0046]
FIG. 5 shows still another modified example. The lower end portion of the back column 9 is pivotally supported by the shaft 11 at the upper end position of the rising portion 8 so as to be tiltable rearward, and obliquely below the pivot 11 of the back column 9. A wire engaging portion 9c extending forward and downward is formed, and a plurality of concave portions 29, 29... Are arranged on the upper surface of the wire engaging portion 9c.
[0047]
On the other hand, the lower end of the wire 31 is bound to a spring receiver 30 capable of moving up and down to support the lower end of the compression spring 15 provided in the rising portion 8, and the wire 31 is shown in an enlarged manner in FIG. Are inserted into a long hole 9d formed in a range where the recesses 29, 29,... Of the wire engagement portion 9c are provided, and an engagement piece 32 fixed to the upper end of the wire 31 is one of the recesses 29, 29,. It can be selectively engaged. The intermediate portion of the wire 31 passes through the side surface of the pin 33 fixed to the rising portion 8, and the wire below the pin 33 is connected to any of the recesses 29, 29. The position of 31 is not changed.
[0048]
In this embodiment, the waist contact portion 10 is constituted by a member provided integrally on the front side of the upper end of the rising portion 8.
[0049]
According to this embodiment, when the engagement piece 32 of the wire 31 is engaged with the recess 29 at a position away from the pivot 11 of the back column 9, the distance from the shaft 11 to the action point is increased and the compression spring 15 is compressed. Since the amount increases, the cushioning property at the time of rearward tilting of the upper half of the backrest 6 becomes stiff, and conversely, if the engagement piece 32 is engaged with the recess 29 near the pivot 11, the distance between the action points becomes short. At the same time, the compression amount of the compression spring 15 is reduced, and the cushioning property of the upper half of the backrest 6 is softened.
[0050]
Therefore, it is possible to obtain an optimal comfort posture simply by pulling the engagement piece 32 and fitting it into one of the recesses 29, 29.
[0051]
FIGS. 6 to 8 show other embodiments of the present invention. FIG. 6 (A) is a side view, FIG. 6 (B) is a rear view, and FIG.
[0052]
The lower end of the back column 9 is pivotally supported at the upper end of the rising portion 8 of the back frame 5 by a shaft 11 so as to allow backward rotation. Left and right dorsal arms 12 and 12 made of material are extended symmetrically, and the tips of these dorsal arms 12 and 12 slide in the vertical direction on the left and right sides above the back plate 13 of the backrest 6 (position corresponding to the thoracic vertebra). It is movably engaged.
[0053]
A waist contact portion 10 is provided at the upper end position of the rising portion 8 of the back frame 5, and the waist contact portion 10 is in contact with the back surface of the waist position a of the backrest 5. The waist contact portion 10 is made to elastically contact the back surface of the waist portion a of the backrest 5 through an elastic body such as rubber or foamed resin, so that the contact when taking the backward tilt posture is softened. In addition, it is preferable.
[0054]
As shown in FIG. 8, the lower end of the back column 9 is extended inside the rising portion 8 of the back frame 5, and a compression spring 34 is interposed between the extended portion 9 e and the waist contact portion 10. The amount of flexure of the compression spring 34 is adjusted by rotating the knob 36 of the adjusting screw 35 that passes through the extending portion 9e and the rising portion 8 from the waist contact portion 10 to adjust the amount of bending of the compression spring 34. The load value at the time of rearward tilt can be adjusted.
[0055]
The backrest 6 is composed of a back plate 13 made of a resin molded product and a cushion attached to the back plate 13. The back plate 6 has a position corresponding to the lumbar portion b from the position corresponding to the waist position a. A plurality of slits 37, 37... Are provided in the required range up to the position in the lateral direction, and the backrest 6 can be bent backward in the range where the slits 37, 37.
[0056]
Regarding the sliding engagement between the tips of the back arms 12 and 12 of the back column 9 and the back plate 13 of the backrest 6, in the example shown in the figure, longitudinal slots 38 provided near the right and left ends of the back surface of the backrest 6. 38 and a slider 39, 39 provided at the tip of the back arms 12, 12 are slidable in the vertical direction. However, the sliding engagement does not necessarily depend on the long hole 38 and the slider 39, but a slide is provided by providing a shoe at the tip of the back arms 12 and 12 and elastically contacting the back of the backrest 6. May be.
[0057]
The same members as those in FIGS. 1 to 3 are denoted by the same reference numerals, and detailed description thereof is omitted.
[0058]
Next, the operation of the above embodiment will be described.
[0059]
When not sitting on a chair with a backrest, as shown in FIGS. 6 (A) and 8 (A), the shaft 7 is used as a fulcrum in the counterclockwise direction in FIG. The back strut 9 is placed in the upright state by the biasing force of the compression spring 34.
[0060]
When sitting on a chair with a backrest and leaning back against the backrest 6 and applying weight, the back frame 5 usually rotates backward and the entire backrest 6 tilts backward as shown by the solid line in FIG. Can take.
[0061]
When leaning further on the backrest 6 from the above posture and taking a comfortable posture, the portion of the human body where the lumbar portion abuts (the lumbar position a) is supported by the lumbar abutment portion 10, and the upper half of the backrest 6 supports the back column 9 on the shaft 11. By tilting backward against the urging force of the compression spring 34, the rearward tilt is caused as indicated by the symbol R in FIG. In the backward tilting of the upper half of the backrest 6, the backward tilting is allowed by sliding between the sliders 39, 39 at the tips of the back arms 12, 12 and the long holes 38, 38 of the backrest 6.
[0062]
Moreover, when the upper part of the backrest 6 is twisted to the left and right, the back arms 12 and 12 are allowed to bend.
[0063]
With respect to the rearward inclination of the upper half of the backrest 6, the knob 36 can be rotated to adjust the elasticity of the compression spring 34, so that it can be set to the user's preference.
[0064]
When working in such an easy posture, the back portion 6 of the human body does not bend and is fixed by the lumbar abutment portion 10 so that it does not become an unnatural body shape, and the thoracic vertebra portion b is free Since it tilts backward, it can maintain the most comfortable posture. Further, the upper part of the backrest 6 follows the delicate body movement due to the flexure of the left and right back arms 12 and 12 so that the shoulder blades do not feel tired.
[0065]
FIG. 9 shows still another embodiment of the present invention. The tip of the mounting portion 9a that is bent forward from the lower end of the back column 9 is bent toward the front of the rising portion 8, and the waist portion A shaft 11 is pivotally supported by the shaft 11 so as to be tilted rearward.
[0066]
A pressing portion 40 is suspended from the lower portion of the back column 9 at a position behind the pivot 11, and a concave elastic body receiving portion 41 is provided on the upper surface of the waist contact portion 10 of the rising portion 8. An elastic body 42 such as rubber is fixed in the elastic body receiving portion 41, and the pressing portion 40 of the back column 9 is configured to abut on the rear surface of the elastic body 42.
[0067]
Therefore, when the upper half of the backrest 6 is tilted backward, the back column 9 pivots backward with the pivot 11 as a fulcrum, and at this time, the pressing portion 40 of the back column 9 presses and deforms the elastic body 42 to cushion. Sex is given.
[0068]
FIG. 10 shows a configuration in which the pressing portion 40 of the back column 9 in the embodiment shown in FIG. 9 is nearly horizontal, and the elastic body 42 is pressed from above when the back column 9 is tilted backward.
[0069]
Further, in FIG. 11, the elastic body receiving portion 41 is provided inside the upper end of the rising portion 8, and the pressing portion 40 of the back column 9 is configured to be nearly vertical so that the elastic body 42 is pressed from the back side. It is.
[0070]
9 to 11, the same members as those in FIGS. 1 to 3 are denoted by the same reference numerals, and detailed description thereof is omitted.
[0071]
12 and 13 are formed integrally with the rising portion 8 and the back column 9 of the back frame 5 by a resin rich in elasticity, and in FIG. 12, it protrudes forward at the waist position a of the backrest 6. It is bent into a V shape, and the tip of the bent portion 43 forms a waist contact portion, and the elasticity of the bent portion 43 provides cushioning for the upper half of the backrest 6. Yes.
[0072]
In FIG. 13, the bent portion 43 is provided at a position above the waist position a, and the waist contact portion 10 projecting forward from the rising portion 8 is positioned at the waist position a.
[0073]
In FIGS. 12 and 13, the same reference numerals are given to members common to FIGS. 1 to 3.
[0074]
【The invention's effect】
As described above, according to the present invention, when leaning against the backrest, the entire backrest is tilted backward by the backward tilting rotation of the backframe, and the upper portion of the backrest rises from the upper end of the rising portion of the backframe. By tilting backward and flexing of the back arm, it is possible to follow the movement of the body without difficulty and to tilt backward and take a stable comfort posture.
[0075]
If the waist position of the backrest is supported by the waist contact part at the upper end of the back frame, the entire backrest will not tilt backwards, and it will fit well with the body and make it easy to lean backward Can take.
[Brief description of the drawings]
FIG. 1 is a side view, partly in section, showing an embodiment of a chair with a backrest according to the present invention.
FIG. 2 is a rear view with the legs removed.
FIG. 3 is a plan view of the same.
4A and 4B show a modification of FIG. 1, in which FIG. 1A is a view corresponding to FIG. 1 and FIG.
5 shows still another modification of FIG. 1, (A) is a view corresponding to FIG. 1, and (B) is an enlarged view of a main part.
6A and 6B show another embodiment of the present invention, in which FIG. 6A is a side view and FIG. 6B is a rear view.
FIG. 7 is an explanatory view showing the operation.
8A and 8B are cross-sectional views showing the operation of the main part of FIG.
FIG. 9 is a side view showing another embodiment of the present invention.
10 is a side view showing a modification of FIG.
FIG. 11 is a side view showing still another modification of FIG. 9;
FIG. 12 is a side view showing another embodiment of the present invention.
13 is a side view showing a modification of FIG.
[Explanation of symbols]
3 Seat 4 Receiving Base 5 Back Frame 6 Back 8 Elevation 9 Back Support 10 Lumbar Contact 12 Back Frame 13 Back Plate 15 Compression Spring 16 Spring Pressure Adjusting Shaft 18 Sliding Member 19 Spring Receiving 24 Rod 26 Projection 27, 29 Recess 31 Wire 32 Engagement piece 33 Pin 34 Compression spring 38 Long hole 39 Slider 40 Pressing part 41 Elastic body receiving part 42 Elastic body 43 Bending part

Claims

The seat has a seat on the pedestal supported by the legs, and the front end of the back frame having a substantially L shape in side view is pivotally supported on the cradle so as to be swingable in the vertical direction, and the back frame is supported by the back frame. In a chair with a backrest, a back strut is provided elastically at a position above the rear raised portion of the back frame so that it can be tilted rearwardly, and this back strut has back arms extending in the left-right direction on both sides of its upper end. , The front ends of these back arms are engaged with the left and right positions of the back of the upper part of the back, and the upper part of the back is tilted backward via the back strut including the back arm,
An elongated hollow part is formed in the vertical direction in the rear rising part,
The back strut is pivotally supported by a pivot so that the lower end front portion thereof can be tilted rearward to the center of the back surface at a position where the human waist portion of the backrest abuts , and is vertically moved into the hollow portion of the rear rising portion of the back frame. built stretchable compression spring in a direction, the is brought into contact with the spring receiving portion of the rear position than the pivot of the back posts on the upper end of the compression spring, the back strut is biased in the standing direction by a compression spring A chair with a backrest characterized by that.

The chair with a backrest according to claim 1, wherein the upper end side of the axis of the compression spring is formed so as to be position-changeable at a plurality of positions in a direction away from and contacting the pivot, and the reaction force of the compression spring can be selected.

A spring pressure adjusting shaft for adjusting the spring pressure of the compression spring is inserted into the hollow portion of the rear rising portion, and a lower end of the compression spring is interposed in a spring seat of the spring pressure adjusting shaft. The chair with a backrest according to claim 1, wherein the spring pressure of the compression spring is adjusted by advancing and retracting the spring seat by rotating a knob provided at a lower end of the spring pressure adjusting shaft.

The seat has a seat on the pedestal supported by the legs, and the front end of the back frame having a substantially L shape in side view is pivotally supported on the cradle so as to be swingable in the vertical direction, and the back frame is supported by the back frame. In a chair with a backrest, a back strut is provided elastically at a position above the rear raised portion of the back frame so that it can be tilted rearwardly, and this back strut has back arms extending in the left-right direction on both sides of its upper end. , The front ends of these back arms are engaged with the left and right positions of the back of the upper part of the back, and the upper part of the back is tilted backward via the back strut including the back arm,
The back column has a lower end pivotally supported at the upper end of the rising portion of the back frame by a pivot so as to be tilted rearward and a compression spring is built in the rising portion, and an upper end of a wire coupled to the lower end of the compression spring. Is formed to be selectively engageable at a plurality of positions of the wire engaging portion extending obliquely forward and downward from the pivot of the back strut, and by changing the engaging position of the upper end of the wire, A chair with a backrest, characterized in that the reaction force can be selected.

The chair with a backrest according to claim 4, further comprising a waist contact portion that protrudes toward a portion where the human waist portion of the backrest hits an upper end front portion of the rising portion of the back frame.

The seat has a seat on the pedestal supported by the legs, and the front end of the back frame having a substantially L shape in side view is pivotally supported on the cradle so as to be swingable in the vertical direction, and the back frame is supported by the back frame. In a chair with a backrest, a back strut is provided elastically at a position above the rear raised portion of the back frame so that it can be tilted rearwardly, and this back strut has back arms extending in the left-right direction on both sides of its upper end. , The front ends of these back arms are engaged with the left and right positions of the back of the upper part of the back, and the upper part of the back is tilted backward via the back strut including the back arm,
The back strut is pivotally supported by a pivot on the upper end of the raised portion of the back frame so as to be able to tilt backward, and a compression spring is interposed between the lower end of the back strut below the pivot and the backrest, A chair with a backrest, wherein the back arm of the column is engaged with the back arm of the backrest so that the compression spring can be expanded and contracted vertically.

The seat has a seat on the pedestal supported by the legs, and the front end of the back frame having a substantially L shape in side view is pivotally supported on the cradle so as to be swingable in the vertical direction, and the back frame is supported by the back frame. In a chair with a backrest, a back strut is provided elastically at a position above the rear raised portion of the back frame so that it can be tilted rearwardly, and this back strut has back arms extending in the left-right direction on both sides of its upper end. , The front ends of these back arms are engaged with the left and right positions of the back of the upper part of the back, and the upper part of the back is tilted backward via the back strut including the back arm,
The back strut and the raised portion of the back frame are integrally formed of an elastic resin, and the back strut and the raised portion are elastic in the extending direction to the back position of the portion where the human waist of the backrest abuts. A chair with a backrest, characterized in that a bent portion is provided, and a protruding end of the bent portion is a waist contact portion.

The seat has a seat on the pedestal supported by the legs, and the front end of the back frame having a substantially L shape in side view is pivotally supported on the cradle so as to be swingable in the vertical direction, and the back frame is supported by the back frame. In a chair with a backrest, a back strut is provided elastically at a position above the rear raised portion of the back frame so that it can be tilted rearwardly, and this back strut has back arms extending in the left-right direction on both sides of its upper end. , The front ends of these back arms are engaged with the left and right positions of the back of the upper part of the back, and the upper part of the back is tilted backward via the back strut including the back arm,
The back strut and the raised portion of the back frame are formed of an elastic resin, and a waist contact portion that protrudes from the back of a portion where the human waist portion of the back is in contact with the upper front portion of the rise portion is provided. A chair with a backrest, wherein a bent portion having elasticity in the extending direction is provided above the waist contact portion.