JP2004147027A

JP2004147027A - Operation panel input device

Info

Publication number: JP2004147027A
Application number: JP2002308878A
Authority: JP
Inventors: Shinji Hashii; 橋井　伸治; Masayuki Kawamura; 川村　昌之; Jun Nakamura; 中村　純; Kenji Otsuka; 大塚　健二
Original assignee: Toto Ltd; SMK Corp
Current assignee: Toto Ltd; SMK Corp
Priority date: 2002-10-23
Filing date: 2002-10-23
Publication date: 2004-05-20
Anticipated expiration: 2022-10-23
Also published as: JP4094402B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide an operation panel input device which enlarges and detects only an increment of light reception by an input operation and can precisely judge the input operation. <P>SOLUTION: An amplification means (18) amplifying a photoelectric conversion signal outputted from a light reception means (6a) is constituted of a differential amplification circuit (18) inputting the photoelectric conversion signal and an offset signal and outputting an amplification signal amplified at a fixed amplification rate (A). An input judgement means (10) outputs the offset signal so that a value of the amplification signal inputted from the differential amplification circuit (18) at every detection period becomes a set value in a next scanning period (T) and operates light reception quantity from values of the inputted amplification signal and the offset signal inputted when the amplification signal is outputted. The amplification signal changes with the set value as a center. Change quantity amplifies a level change of the photoelectric conversion signal at the amplification rate (A). Consequently, it can securely be detected even if the change by the input operation is small. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、主に家電機器へ種々の入力操作を行う為の操作パネル入力装置に関し、更に詳しくは、操作パネルに触れずに入力操作が可能な操作パネル入力装置に関する。
【０００２】
【従来の技術】
【０００３】
給湯器や洗濯機等の家電機器には、これらの機器を操作するための操作スイッチが集中して取り付けられた操作パネルが備えられている。操作者は、この操作スイッチのいずれかを指で押圧することによって、機器に対して所定の動作制御を行う。
【０００４】
しかしながら、操作スイッチを直接指で押圧して操作する構造である為、可動部品を使用せざるを得ず、その耐久性に問題があり、また、操作スイッチの表面を指が触れることによって汚れ、操作パネルの美感を損なうという問題があった。
【０００５】
このようなことから、操作パネルを直接指で触れずに所定の操作を実行することができる非接触式の操作パネル入力装置が知られている（例えば、特許文献１）。
【０００６】
【特許文献１】
特開２０００−１００２８７（第４頁、図２）
【０００７】
図９は、この従来の操作パネル入力装置１００を示すもので、透明のアクリル板で形成された操作パネル１０１の内方に、家電機器への制御内容に対応させて複数組の光スイッチユニットＵ_１（例えば、家電機器の電源をＯＮ制御する）、Ｕ_２・・が配置されている。
【０００８】
各組の光スイッチユニットＵは、４５５Ｋ_ＨＺの固有周波数の赤外線検出信号を発光する赤外発光素子１０２と、赤外発光素子１０２から発光される赤外線検出信号を受光可能な赤外受光素子１０３とで構成されている。
【０００９】
各光スイッチユニットＵから発光される赤外線検出信号は、図１０に示すように、互いに他の光スイッチユニットＵ_１、Ｕ_２・・から発光される赤外線検出信号と重複しないようように、所定の走査周期Ｔで繰り返し赤外発光素子１０２から発光される。
【００１０】
図９に示すように、同一の光スイッチユニットＵで対となる赤外発光素子１０２と赤外受光素子１０３は、隣り合うようにプリント配線基板１０４上に実装され、これらの光スイッチユニットＵと操作パネル１０１の間には、赤外線のみを透過させる赤外フィルタ１０５が配設されている。
【００１１】
従って、各組の赤外発光素子１０２から発光される赤外線検出信号は、その上方の赤外フィルタ１０５と操作パネル１０１を通過して外方に出力され、又、外来光の内、赤外線検出信号を含む赤外線のみが、その近傍の操作パネル１０１と赤外フィルタ１０５を透過して赤外受光素子１０３に到達する。
【００１２】
赤外受光素子１０３の出力側には、４５５Ｋ_ＨＺの固有周波数の光電変換信号を通過させるバンドパスフィルタを介して、光スイッチユニットＵへの入力操作を判定するマイコンが備えられている。従って、赤外受光素子１０３が、固有周波数の赤外線検出信号を受光した場合にのみ、その光電変換信号がマイコンへ入力される。これにより、自然光、他のリモコン送信信号などと、赤外発光素子１０２から発光された赤外線検出信号とを、受光手段１０３により識別することができる。
【００１３】
光スイッチユニットＵの近傍に、赤外線検出信号を反射させるような物体が存在しない場合には、所定の走査周期で赤外発光素子１０２から発光される赤外線検出信号を、同一光スイッチユニットＵの対となる赤外受光素子１０３が受光することはなく、マイコンに、光電変換信号が入力されない。この状態では、マイコンは、光スイッチユニットＵに対する入力操作は行われていないものと判定する。
【００１４】
一方、下方に光スイッチユニットＵ_１が配置された操作パネル１０１へ、例えば指を近づけて入力操作を行うと、赤外発光素子１０２から発光される赤外線検出信号は、操作パネル１０１の上方に接近する指で反射され、再び、操作パネル１０１と赤外フィルタ１０５を透過して、同じ光スイッチユニットＵ_１の赤外受光素子１０３に入力される。マイコンは、赤外受光素子１０３で光電変換された光電変換信号を、同じ光スイッチユニットＵ_１の赤外発光素子１０２が赤外線検出信号を発光したタイミングとほぼ同時に入力すると、その光スイッチユニットＵ_１に対して入力操作が行われたものと判定し、家電機器に対して例えば電源をＯＮとする制御信号を出力する。
【００１５】
このときに、他の光スイッチユニットＵ_２の赤外受光素子１０３においても、指で反射された赤外線検出信号を受光することがあるが、その光スイッチユニットＵ_２の赤外発光素子１０２が赤外線検出信号を発光するタイミングと異なるタイミングで、光電変換信号がマイコンに入力されるので、その光スイッチユニットＵ_２に対する入力操作とは認識しない。
【００１６】
ところで、操作パネル１０１の上方に接近する指で反射され、再び、操作パネル１０１と赤外フィルタ１０５を透過して、赤外受光素子１０３に入力される赤外線検出信号は微弱なものであり、一般に、指を接近させていないときに赤外受光素子１０３に入力されるた受光量に比較してその増加分は、極めてわずかなレベルである。
【００１７】
そこで、図１１に示す操作パネル入力装置１１０では、赤外受光素子１１６で赤外線検出信号から光電変換した光電変換信号を、増幅回路１１１で増幅し入力操作を判定するマイコン１１２へ出力している（例えば、未公開特許文献１）。
【００１８】
【未公開特許文献１】
特願２００２−１６８４６１号（項目
【００１９】、図３）
すなわち、赤外発光素子１１３から発光され指１１４で反射された赤外線検出信号は、透明な操作パネル１１５を通過して、赤外受光素子１１６で受光される。赤外受光素子１１６は、この受光した赤外線検出信号を光電変換信号に変換して、出力側に接続された増幅回路１１１で増幅し、入力操作を判定するマイコン１１２へ出力している。
【００２０】
【発明が解決しようとする課題】
【００２１】
この操作パネル入力装置１１０では、赤外受光素子１１６の受光量を表す光電変換信号を全て増幅回路１１１で増幅するので、例えば、マイコン１１２でＡ／Ｄ変換してその値を読み取る場合に、そのリファレンス電圧を越え読み取りできない場合が生じていた。
【００２２】
そこで、光電変換信号の入力レベルによって増幅回路１１１の増幅率Ａを変化させ、マイコン１１２による読み取り範囲内（Ａ／Ｄコンバータの入力電圧範囲）内のレベルに安定化させて出力するＡＧＣ（オートゲインコントロール）回路を備えた増幅回路を用いたり、光電変換信号を微分回路に通して出力し、その変化分をマイコン１１２で検出する方法が考えられるが、指で反射された赤外線検出信号を受光することによる光電変換信号の微弱な増加量に比べて、走査周期Ｔ毎に赤外受光素子が点滅し、若しくは外来光が種々の要因で変化することによる光電変換信号のレベル変化がはるかに大きく、いずれの方法であっても、上記入力操作による増加分のみを正確に検出することが困難なものであった。
【００２３】
このようなことから、直接操作パネルに触れずに入力操作を行うことが可能なこの種の操作パネル入力装置が望まれているにもかかわらず、その入力操作を正確に判定できず、普及の障害となっているものであった。
【００２４】
本発明は、このような従来の問題点を考慮してなされたものであり、入力操作による受光量の増加分のみを拡大して検出し、これにより正確に入力操作を判定できる操作パネル入力装置を提供することを目的とする。
【００２５】
また、外来光の変化による増加分のみを拡大し、これにより、外来光による受光量の微弱な変化を正確に判定し、入力操作と同じように外来光が変化することにより入力操作と誤判定した場合であっても、これを無効とする操作パネル入力装置を提供することを目的とする。
【００２６】
【課題を解決するための手段】
【００２７】
請求項１の操作パネル入力装置は、少なくとも一部が光透過部となった操作パネルと、操作パネルの内方に配置され、操作パネルの光透過部から外方へ光検出信号を発光する発光手段と、光透過部の外方で反射された光検出信号を受光可能な受光手段とを対として有する光スイッチユニットと、光スイッチユニットの発光手段に対し、少なくとも入力操作時間より短い走査周期で光検出信号を繰り返し発光させる発光制御手段と、発光手段が光検出信号を発光する走査周期内に定めた検出期間に、対となる受光手段に対し受光量を検出させ、受光量を表す光電変換信号を出力させる受光制御手段と、受光手段から出力される光電変換信号を増幅し、増幅信号を出力する増幅手段と、増幅信号から受光手段が検出した受光量を求め、光スイッチユニットに対する入力操作状態を判定する入力判定手段と、を備えた操作パネル入力装置であって、
増幅手段を、一対の入力端子から入力される光電変換信号とオフセット信号とを、固定した増幅率で増幅し、出力端子から増幅信号を出力する差動増幅回路で構成し、入力判定手段は、差動増幅回路から検出期間毎に入力される増幅信号の値が、次の走査周期の当該検出期間に予め設定した設定値となるように、差動増幅回路の一方の入力端子へオフセット信号を出力し、入力される増幅信号と、差動増幅回路がその増幅信号を出力する際に一方の入力端子から入力されたオフセット信号との各値から受光量を演算することを特徴とする。
【００２８】
差動増幅回路の一方の入力端子に入力されるオフセット信号は、走査周期の検出期間ごとに受光手段から出力される光電変換信号との差を固定した増幅率で増幅したときに、一定値である設定値となるような値として出力されるので、差動増幅回路から出力される増幅信号の値は、設定値を中心に変化し、その変化量は、光電変換信号のレベル変化を増幅率で増幅した値となる。
【００２９】
従って、入力操作による光電変換信号の値のわずかな増加は、入力判定手段に入力される増幅信号の値に増幅して表れ、一方、その際に差動増幅回路に入力されるオフセット信号の値は、一走査周期前に入力判定手段が出力したもので求めることができるので、既知の増幅率、オフセット信号及び入力された増幅信号の各値から算出し、入力操作による光電変換信号の値を拡大して読み取り、正確に入力操作状態を判定できる。
【００３０】
この算出処理は、走査周期の特定した各検出期間毎に行うので、赤外受光素子が点滅する等の光電変換信号の値に大きな変化が発生する時間を含まず、オフセット信号値を大きく設定し直すことなく、速やかに算出できる。
【００３１】
また、請求項２の操作パネル入力装置は、入力判定手段が、増幅信号をＡ／Ｄ変換して入力するＡ／Ｄ変換部と、Ｄ／Ａ変換したオフセット信号を差動増幅回路の一方の入力端子へ出力するＤ／Ａ変換部と、デジタル信号である増幅信号とオフセット信号とから受光量を演算する演算部とを有し、設定値は、Ａ／Ｄ変換部がＡ／Ｄ変換可能な入力電圧範囲のほぼ中央に設定されることを特徴とする。
【００３２】
設定値をＡ／Ｄ変換部の入力電圧のほぼ中央に設定するので、増幅信号の値は、入力電圧のほぼ中央を中心に変動し、光電変換信号の変化をＡ／Ｄ変換部で確実に読み取ることができる。
【００３３】
また、請求項３の操作パネル入力装置は、走査周期内に定めた検出期間が、発光手段が光検出信号を発光する発光期間（ｔｏｎ）であり、発光期間（ｔｏｎ）に受光手段が検出した発光時受光量（Ｌｏｎ（ｃ））を、少なくとも一走査周期前の発光期間（ｔｏｎ）に受光手段が検出した発光時受光量（Ｌｏｎ（ｏ））と比較して、所定の入力しきい値を越えて増加したときに、光スイッチユニットに対する入力操作と判定することを特徴とする。
【００３４】
操作体が光スイッチユニットＵに接近すると、操作体で反射し受光手段に到達する光検出信号が増加し、その結果、新たに検出される発光時受光量は、少なくとも一走査周期前の発光時受光量に比べて増加し、この発光時受光量の変化を増幅した増幅信号を入力判定手段が読み取るので、変化量を所定の入力しきい値と比較することにより、入力操作のタイミングまで、正確に判定できる。
【００３５】
また、内部散乱光や外来光が経年変化などで緩やかに変動しても、比較する発光時受光量の差には表れないので、これらの変動に影響されずに入力操作を判定できる。
【００３６】
また、請求項４の操作パネル入力装置は、走査周期内に定めた検出期間が、発光手段が光検出信号を発光する発光期間（ｔｏｎ）と、光検出信号を発光させない消灯期間（ｔｏｆｆ）であり、入力判定手段は、発光期間（ｔｏｎ）と消灯期間（ｔｏｆｆ）のそれぞれについて、検出期間毎に入力される増幅信号の値が、次の走査周期の当該検出期間に予め設定した設定値となるようにオフセット信号を生成して、次の走査周期の当該検出期間に差動増幅回路の一方の入力端子へ生成したオフセット信号を出力し、消灯期間（ｔｏｆｆ）に受光手段が検出した消灯時受光量（Ｌｏｆｆ）を、少なくとも一走査周期前の消灯期間（ｔｏｆｆ）に受光手段が検出した消灯時受光量（Ｌｏｆｆ（ｏ））と比較して、所定の環境しきい値を越えたときに、光スイッチユニットに対する入力操作の判定を、一定期間無効とすることを特徴とする。
【００３７】
受光手段が検出する消灯時受光量には、光検出信号が含まれないので、入力操作とは無関係な外来光若しくは内部散乱光の光量が表れる。外来光若しくは内部散乱光の一時的な増加が、入力操作による受光量の増加と同程度に微弱なものであっても、消灯時受光量の変化を増幅した増幅信号を入力判定手段が読み取るので、変化量を所定の環境しきい値と比較することにより、外来光若しくは内部散乱光の一時的な増加とみなすことができる。
【００３８】
従って、外来光若しくは内部散乱光の一時的な増加により、発光時受光量も増加し入力操作と判定されることがあるが、外来光若しくは内部散乱光の一時的な増加とみなして、入力操作の判定を一定期間無効とし、外来光などによる機器の誤動作を防止できる。
【００３９】
入力判定手段から出力するオフセット信号の値は、走査周期の発光期間と消灯期間のそれぞれについて設定するので、発光時受光量と消灯時受光量間の値が大きく異なるものであっても、オフセット信号値を大きく設定し直すことなく、速やかに算出できる。
【００４０】
【発明の実施の形態】
以下、本発明に係る操作パネル入力装置１の一実施の形態を、図１乃至図８で説明する。
【００４１】
図１は、操作パネル入力装置１の斜視図で、家電機器であるユニットバスに付帯する設備の給湯器（図示せず）に備えられるものである。本発明に係る操作パネル入力装置は、防水性が求められる洗濯機、風呂の給湯器などに特に適しているが、音響機器、空調機器など他の電気機器を制御する入力装置としてこれらに付属して備えるものでもよい。
【００４２】
操作パネル入力装置１は、外方（図２において上方側）から、操作パネルとなる矩形の透明アクリル板３、液晶表示パネル４、バックライトパネル７、反射板９、プリント配線基板１３が積層して配置されたもので、これらは、積層された状態で互いの対向面が貼り付けられ、合成樹脂製のケース２内に収容されている。
【００４３】
ケース２は、外方に開口する枡形の基台２ａと、枡形周囲に嵌合し、枡形の上方に固定枠２２が突き出た押さえカバー２ｂとからなり、両者のフランジ部に挿通させる取り付けネジ２３により一体化される。
【００４４】
ケース２と透明アクリル板３との間には、接着剤、粘着剤等が塗布され、操作パネル入力装置１内に水滴、埃等が侵入しないようになっている。
【００４５】
透明アクリル板３の周囲に固定枠２２の厚み分の段差を設けることにより、透明アクリル板３とその周囲のケース２の表面は、同一平面上に整列する。
【００４６】
液晶表示パネル４は、給湯器に対して入力操作を行う制御内容と、給湯器の動作に関する所定の表示を、透明アクリル板３を通して表示するもので、図１に示す給湯器では、主電源の入力、給湯動作のスタート、追いだきの選択等の入力操作を示す表示３０ａ、３０ｂ、３０ｃ・・が、矩形枠で表示した操作エリア３０Ａ、３０Ｂ、３０Ｃ・・とともに表示される。また、この表示では、浴槽への給湯量３１、給湯温度３２が表示されている。
【００４７】
この液晶表示パネル４による表示は、図示しない液晶ドライバーの制御により、表示されるもので、操作エリアと入力操作を示す表示３０の位置と数、及びその他の表示は、給湯器の動作状態に応じて可変するようになっている。
【００４８】
バックライトパネル７は、液晶表示パネル４の表示を内方から照光するもので、その端面に配置されるバックライト光源４０（図３参照）からのバックライト光を、その内部に導光している。バックライトパネル７は、表面（液晶表示パネル４との対向面）に拡散シート７Ａが貼り付けられた透明なアクリル板で形成され、また、背面側には、対向面を白色とした反射板９が配置されるので、バックライト光源から発光されるバックライト光は、バックライトパネル７の内部で、散乱しながら外方に導光される。これにより、透明アクリル板３の外方からは、特定のバックライト光源は確認されず、あたかも液晶表示パネル４による表示の背景全体がバックライト光により照光されたように見える。
【００４９】
本実施例では、バックライトパネル７とバックライト光源４０は、操作エリア３０毎にしきり板３３により区切られ、操作エリア３０の背面を、異なる光源で照光するようになっている。
【００５０】
反射板９は、上述のように表面に白色の塗料を塗布することにより、バックライトパネル７との対向面を白色とし、バックライト光を下方に逃げないようにバックライトパネル７内に反射させている。白色とするので、バックライト光を所定の色彩に着色すれば、液晶表示パネル４の背景は、その色彩に変化したように目視される。反射板９には、後述する発光素子５ａの図３において上方（表面側）に出力側小孔３４が、受光素子６ａの上方に入力側小孔３５が穿設されている。これらの小孔３４、３５は、例えば、内径が１乃至１．５ｍｍ程度の小孔であり、また、バックライトパネル７の表面側の拡散シート７Ａにより光路が散乱されるので、透明アクリル板３の外方からは、目視されない。
【００５１】
反射板９の背面側に取り付けられるプリント配線基板１３には、操作パネル３に表示される操作エリア３０Ａ、３０Ｂ、３０Ｃ・・のそれぞれに対応させて光スイッチユニットＵ_１、Ｕ_２、Ｕ_３、・・が配置されている（図４参照）。各光スイッチユニットＵは、赤外発光素子５ａを有する発光手段５と、赤外発光素子５ａから発光される赤外光検出信号を受光可能な赤外受光素子６ａを有する受光手段６とを、対として構成されている。本実施の形態では、赤外発光素子５ａとして赤外発光ダイオードを、赤外受光素子として、ピンフォトダイオードをそれぞれ用いている。
【００５２】
図３に示すように、同一光スイッチユニットＵの赤外発光素子５ａと赤外受光素子６ａは、プリント配線基板１３に穿設された出力孔３６と入力孔３７内に、それぞれの発光面と受光面を臨ませて、プリント配線基板１３の背面側に実装されている。尚、赤外受光素子６ａの受光面には、赤外光検出信号の赤外線のみを透過させる赤外フィルタ８が形成されている。
【００５３】
出力孔３６と入力孔３７は、その表面側に積層された反射板９の出力側小孔３４と入力側小孔３５の内径よりやや大きい内径で、それぞれ出力側小孔３４と入力側小孔３５に同一軸線上に連通するもので、これにより、各光スイッチユニットＵの赤外発光素子５ａから発光される赤外光検出信号は、出力孔３６と出力側小孔３４を通過して、透明アクリル板３から外方に放射され、又、透明アクリル板３の外方から受ける光は、入力側小孔３５と入力孔３７を通過し、更に赤外フィルタ８を通過することにより、赤外光検出信号を含む赤外線が赤外受光素子６ａに入力される。
【００５４】
図４は、本実施の形態に係る操作パネル入力装置１の各回路構成を示すブロック図、図５は、その要部の回路構成を示すブロック図であり、以下、これらのブロック図に沿って操作パネル入力装置１をその作用とともに説明する。
【００５５】
各光スイッチユニットＵ_１、Ｕ_２、Ｕ_３の赤外発光素子５ａは、それぞれマイコン１０によって接続制御されるＬＥＤマルチプレクサ１６に接続し、発光制御手段として作用するマイコン１０により制御される発光タイミングで赤外光検出信号を発光する。すなわち、図６に示すように、各スイッチユニットＵ_１、Ｕ_２、Ｕ_３の赤外発光素子５ａは、前後に０．５ｍｓｅｃの消灯期間ｔｏｆｆをおいて０．５ｍｓｅｃの発光期間ｔｏｎ、他の赤外発光素子５ａと重複しないタイミングで赤外光検出信号を発光するもので、前後の消灯期間ｔｏｆｆには、いずれの赤外発光素子５ａからも赤外光検出信号を発光しない。
【００５６】
発光制御は、全ての赤外発光素子５ａについて発光制御した後再び繰り返され、その一走査周期Ｔは、入力操作に要する時間に比べて短い時間に設定される。操作者が入力操作に要する時間は、個人差があるが経験的に５０ｍｓｅｃから２００ｍｓｅｃと推定し、ここでは５０ｍｓｅｃより短い１５ｍｓｅｃとしている。
【００５７】
一方、各光スイッチユニットＵ_１、Ｕ_２、Ｕ_３の赤外発光素子５ａのそれぞれについて対となる赤外受光素子６ａは、マイコン１０によって接続制御されるＰｄマルチプレクサ１７に接続し、受光制御手段としても作用するマイコン１０で制御される検出期間に検出した受光量を光電変換して出力する。
【００５８】
この赤外受光素子６ａの検出期間は、対となる発光素子５ａを発光制御する走査周期Ｔに同期するもので、それぞれ対となる赤外受光素子６ａについてその検出期間が設定される。ここでは、図６に示す各スイッチユニットＵ_１、Ｕ_２、Ｕ_３の対となる赤外発光素子５ａが発光している発光期間ｔｏｎを、それぞれの赤外受光素子６ａの検出期間としている。
【００５９】
図５に拡大して示すように、Ｐｄマルチプレクサ１７の出力側には、増幅率（電圧利得）Ａが固定（ここでは、Ａ＝３０倍）の差動増幅回路であるオペアンプ１８が接続されている。このオペアンプ１８の一方の非反転入力端子１８ｂは、Ｐｄマルチプレクサ１７の出力に接続し、非反転入力端子１８ｂに、各赤外受光素子６ａのマイコン１０で制御される検出期間に受光した受光量を表す光電変換信号が入力される。また、他方の反転入力端子１８ａは、マイコン１０のＤ／Ａコンバータ２０に接続し、マイコン１０で後述する方法で生成され、Ｄ／Ａコンバータ２０から出力されるオフセット信号が入力されるようになっている。
【００６０】
従って、オペアンプ１８の出力端子１８ｃには、オフセット信号と光電変換信号の各値の差が増幅率Ａで増幅された増幅信号が現れ、この増幅信号は、マイコン１０のＡ／Ｄコンバータ１９に出力される。
【００６１】
Ａ／Ｄコンバータ１９は、マイコン１０で演算処理するために、入力される増幅信号を２値データの増幅信号値に変換して演算部２４へ出力するもので、ここでは、０乃至３．３Ｖの入力電圧を８ビットの２値データに変換するＡ／Ｄコンバータを用いている。
【００６２】
また、Ｄ／Ａコンバータ２０は、演算部２４から出力される８ビットの２値データで表されるオフセット信号値を、アナログ信号のオフセット信号に変換してオペアンプ１８の反転入力端子１８ａへ出力するもので、ここでは、０から３Ｖまで変化する光電変換信号の値に合わせて、０乃至３．３Ｖのオフセット信号が出力されるようになっている。
【００６３】
上述のように、赤外受光素子６ａは、マイコン１０で受光制御される発光期間ｔｏｎ中に光電変換信号を連続出力し、オペアンプ１８の出力端子１８ｃからは、発光期間ｔｏｎに入力されたオフセット信号との差を増幅率Ａで増幅した増幅信号が連続して出力されるが、図７に示すように、マイコン１０ではこの各発光期間ｔｏｎ中に４回割込処理を行って（図中１２から１５の割込時間）、Ａ／Ｄコンバータ１９から増幅信号値を得ている。
【００６４】
演算部２４では、Ａ／Ｄコンバータ１９から読み込んだ４回の増幅信号値を平均して、その発光期間ｔｏｎに入力された増幅信号値とするもので、これにより、１回の検出に誤差が生じても、演算して求める受光量への影響を減じている。
【００６５】
マイコン１０で生成され、Ｄ／Ａコンバータ２０から出力されるオフセット信号の値は、平均して求めた上述の増幅信号値が、次の走査周期Ｔの発光期間ｔｏｎにおいて、同一レベルの光電変換信号がオペアンプ１８に入力されたものと仮定し、予め特定の設定値となるように設定する。
【００６６】
ここでは、設定値を、Ａ／Ｄコンバータ１９のリファレンス電圧（０，３．３Ｖ）の中央値（１．６５Ｖ）に設定し、光電変換信号の変化が拡大されて増幅信号の変化に表れても、増幅信号の値をリファレンス電圧（０，３．３Ｖ）の中央を中心に変動させ、広範囲でＡ／Ｄ変換するようにしている。
【００６７】
例えば、各２値データを１０進で表し、新たにＡ／Ｄコンバータ１９から読み込み平均して求めた増幅信号値をＡＤ（ｃ）、その増幅信号を出力する際に反転入力端子１８ａに入力されたオフセット信号を出力するためにＤ／Ａコンバータ２０に入力されるオフセット値をＯＦ（ｏ）、設定値を１２８とすれば、新たに生成しＤ／Ａコンバータ２０へ出力されるオフセット信号値ＯＦ（ｃ）は、ＯＦ（ｃ）＝ＯＦ（ｏ）＋（ＡＤ（ｃ）−１２８）／増幅率Ａで表される。
【００６８】
演算部２４で生成されるオフセット信号値ＯＦ（ｃ）は、８ビットデータであり、このオフセット信号値ＯＦ（ｃ）は、発光期間ｔｏｎ毎に新たに生成され、少なくとも次の発光期間ｔｏｎまで記憶部２５に記憶される。
【００６９】
演算部２４では、赤外受光素子６ａの発光期間ｔｏｎの発光時受光量Ｌｏｎ（ｃ）を、この増幅信号値ＡＤ（ｃ）と、記憶部２５から読み出す一走査周期Ｔ前のオフセット値ＯＦ（ｏ）とから算出する。すなわち、増幅信号値ＡＤ（ｃ）をＤ／Ａ変換した増幅信号の値を増幅率Ａで割り、オフセット信号値ＯＦ（ｏ）をＤ／Ａ変換したオフセット信号の値を加えれば、発光期間ｔｏｎに赤外受光素子６ａが光電変換した光電変換信号の値を算出でき、この算出値を赤外受光素子６ａが検出した発光時受光量Ｌｏｎ（ｃ）とする。
【００７０】
尚、受光量を光電変換した光電変換信号の値は、各赤外受光素子６ａ毎に異なるので、オフセット信号値ＯＦ（ｃ）は、各赤外受光素子６ａについて発光期間ｔｏｎ毎に設定され、記憶部２５に記憶される。
【００７１】
検出した発光時受光量Ｌｏｎ（ｃ）は、マイコン１０において後述の発光時受光量Ｌｏｎ（ｏ）と比較されるとともに、スイッチユニットＵ毎に、マイコン１０に接続される４段からなるシフトレジスタ２１の最下段に記憶される。
【００７２】
同様の処理は、各スイッチユニットＵ_１、Ｕ_２、Ｕ_３について走査周期Ｔ毎に繰り返され、新たに検出された発光時受光量Ｌｏｎ（ｃ）がシフトレジスタ２１の最下段に記憶されるとともに、各段に記憶された受光量は、順次上位段に移される。その結果、特定のスイッチユニットＵについて、シフトレジスタ２１の最上位段に記憶された発光時受光量Ｌｏｎ（ｏ）は、同一スイッチユニットＵについての新たな受光量検出時の４Ｔ時間前、つまり６０ｍｓｅｃ前に検出した受光量を表すものとなる。
【００７３】
図８は、特定のスイッチユニットＵに対して、操作体である指１１を接近させた後離間させる入力操作状態について、各走査周期Ｔ毎にマイコン１０で検出した発光時受光量Ｌｏｎを実線で結び、発光時受光量Ｌｏｎの変化を表したグラフである。
【００７４】
同図のＴ１乃至Ｔ２時は、入力操作前の待機状態であり、指１１がスイッチユニットＵから離間しているので、赤外受光素子６ａは、外来光と内部で散乱する赤外光検出信号を受光し、発光時受光量Ｌｏｎが１Ｖとなっている。
【００７５】
この待機状態からの入力操作で指１１を接近させると、指１１で反射される赤外光検出信号が徐々に増加して発光時受光量Ｌｏｎが増加し、最もスイッチユニットＵへ接近させたＴ７時で約１．５Ｖのピークに達する。
【００７６】
その後、指１１を離間させていくと、反射される赤外光検出信号が徐々に減少して発光時受光量Ｌｏｎも減少し、Ｔ１２時で待機状態約の１Ｖに戻る。
【００７７】
本実施の形態では、指１１の接離に応じてこのように変化する発光時受光量Ｌｏｎから入力操作状態を検出するもので、マイコン１０で、新たに検出した発光時受光量Ｌｏｎ（ｃ）を、シフトレジスタ２１の最上位段に記憶された発光時受光量Ｌｏｎ（ｏ）と比較して、所定の入力しきい値、ここでは０．３ｖを越えて増加したときに、入力操作と判定する。
【００７８】
例えば、図８において、Ｔ５時の発光時受光量Ｌｏｎ（ｃ）は１．２５Ｖ、４Ｔ時間前の発光時受光量Ｌｏｎ（ｏ）は１Ｖであるので、その差は入力しきい値を越えず、続くＴ６時に、発光時受光量Ｌｏｎ（ｃ）が１．４Ｖ、４Ｔ時間前のＴ２時発光時受光量Ｌｏｎ（ｏ）が１Ｖであるので、入力しきい値０．３Ｖを越え、入力操作と判定される。
【００７９】
また、マイコン１０で、新たに検出した発光時受光量Ｌｏｎ（ｃ）を、シフトレジスタ２１の最上位段に記憶された発光時受光量Ｌｏｎ（ｏ）と比較して、所定の解除しきい値、ここでは０．３ｖ以上減少したときに、入力操作の解除と判定する。
【００８０】
例えば、図８において、Ｔ１０時の発光時受光量Ｌｏｎ（ｃ）は１．３Ｖ、４Ｔ時間前の発光時受光量Ｌｏｎ（ｏ）は１．４Ｖであるので、解除しきい値は越えず、続くＴ１１時に、発光時受光量Ｌｏｎ（ｃ）が１．１Ｖ、４Ｔ時間前のＴ７時発光時受光量Ｌｏｎ（ｏ）が１．５Ｖであるので、解除しきい値０．３Ｖを越え、入力操作の解除と判定される。
【００８１】
マイコン１０では、上記入力操作及び入力操作の解除の判定を、各スイッチユニットＵ_１、Ｕ_２、Ｕ_３毎に、新たに検出した発光時受光量Ｌｏｎ（ｃ）とシフトレジスタ２１から読み出した発光時受光量Ｌｏｎ（ｏ）と比較して行う。
【００８２】
マイコン１０において、特定のスイッチユニットＵに対する入力操作と判定すると、そのスイッチユニットＵについて対応づけられた命令を給湯器に対して実行する。例えば、主電源の入力の入力操作を示す表示３０ａを表示した操作エリア３０Ａの下方に配置されたスイッチユニットＵ_１に対して入力操作と判定すると、給湯器の電源がＯＮとなる。
【００８３】
本実施の形態によれば、入力操作状態による光電変換信号の０．１Ｖ程度のわずかな変化部分のみを増幅手段１８で拡大するので、発光素子５ａの点滅による光電変換信号の大きなレベル変化があっても、Ａ／Ｄコンバータ１９の入力電圧範囲内で読み取り、確実にその入力操作状態を判定できる。
【００８４】
更に、入力操作の解除のタイミングを含む各スイッチユニットＵ毎の入力操作状態を判定できるので、入力操作の解除の判定で別の命令を出力したり、入力操作と入力操作の解除を判定した時間間隔で、入力操作の判定を確定させるなどその判定結果を種々の用途に利用できる。
【００８５】
また、経年変化や外来光が徐々に変化する影響を受けて、赤外受光素子６ａが受光する発光時受光量Ｌｏｎのレベルが徐々に変化する場合であっても、入力操作若しくは入力操作の解除の判定において比較する発光時受光量Ｌｏｎ（ｃ）と発光時受光量Ｌｏｎ（ｏ）のいずれもその影響を受けるので、その差には表れず、これらの変化があっても正確に入力操作状態を判定できる。
【００８６】
上述の第１実施の形態では、室内のカーテンが開けられたり、照明が点灯される、虫などが接近するなどの種々の原因で、赤外受光素子６ａに到達する外来光や内部散乱光が一時的に変化することがあり、これらの変化が希に入力操作による光量変化と同様に増加する場合には、入力操作と誤判定する恐れがある。
【００８７】
このように誤判定するような状態を検出し、一定期間入力操作の判定を無効とし、家電機器などの被制御機器の誤動作を防止する目的で、以下に説明するこの第２実施の形態では、受光制御手段とし作用するマイコン１０が、第１実施の形態で、図６に示す各スイッチユニットＵ_１、Ｕ_２、Ｕ_３の赤外発光素子５ａを発光させている発光期間ｔｏｎに加えて、更に、その直前の消灯期間ｔｏｆｆにおいても受光量を検出するものである。
【００８８】
消灯期間ｔｏｆｆにおいて受光量を検出する詳細は、発光期間ｔｏｎにおける検出と同様で、図７に示すように、マイコン１０では各消灯期間ｔｏｆｆ毎にそれぞれで４回割込処理を行って（図中１２から１５の割込時間）、Ａ／Ｄコンバータ１９から増幅信号値を得ている。
【００８９】
演算部２４では、消灯期間ｔｏｆｆにＡ／Ｄコンバータ１９から読み込んだ４回の受光量を平均して、新たに検出された増幅信号値とする。この増幅信号値から消灯時受光量Ｌｏｆｆ（ｃ）を検出するにあたっても、発光時受光量Ｌｏｎ（ｃ）の検出と同様である。
【００９０】
すなわち、Ｄ／Ａコンバータ２０から出力されるオフセット信号の値は、新たに検出される増幅信号値が、次の走査周期Ｔの消灯期間ｔｏｆｆにおいて、Ａ／Ｄコンバータ１９の入力電圧範囲の中央値（１．６５Ｖ）となるように設定される。このオフセット値ＯＦ（ｏ）は、発光期間ｔｏｎについて記憶するオフセット値ＯＦ（ｏ）と同様、各赤外受光素子６ａについて各消灯期間ｔｏｆｆ毎に設定され、記憶部２５に記憶される。
【００９１】
赤外受光素子６ａの消灯期間ｔｏｆｆの消灯時受光量Ｌｏｆｆ（ｃ）は、新たに検出した増幅信号値ＡＤ（ｃ）と、記憶部２５から読み出す一走査周期Ｔ前のオフセット値ＯＦ（ｏ）とから算出する。
【００９２】
すなわち、増幅信号値ＡＤ（ｃ）をＤ／Ａ変換した増幅信号の値を増幅率Ａで割り、オフセット信号値ＯＦ（ｏ）をＤ／Ａ変換したオフセット信号の値を加えて、消灯期間ｔｏｆｆに赤外受光素子６ａが光電変換した光電変換信号の値を算出し、この算出値を赤外受光素子６ａが検出した消灯時受光量Ｌｏｆｆ（ｃ）とする。
【００９３】
検出した消灯時受光量Ｌｏｆｆ（ｃ）は、発光時受光量Ｌｏｎ（ｃ）と同様に、スイッチユニットＵ毎にシフトレジスタ２１の最下段に記憶され、新たに検出された消灯時受光量Ｌｏｆｆ（ｃ）がシフトレジスタ２１の最下段に記憶される毎に順次上位段に移される。
【００９４】
マイコン１０では、各スイッチユニットＵについて、新たに検出された消灯時受光量Ｌｏｆｆ（ｃ）と、シフトレジスタ２１の最上位段に記憶された消灯時受光量Ｌｏｆｆ（ｏ）、つまり４Ｔ時間（６０ｍｓｅｃ）前に検出した消灯時受光量Ｌｏｆｆ（ｏ）とを比較し、外来光と内部散乱光の異常増加を検出する。
【００９５】
すなわち、新たに検出された消灯時受光量Ｌｏｆｆ（ｃ）が、その４Ｔ時間前に検出した消灯時受光量Ｌｏｆｆ（ｏ）に比べて、所定の環境しきい値、ここでは０．３ｖを越えて増加したときには、外来光と内部散乱光の異常増加と判定し、所定期間（例えば数秒）全てのスイッチユニットＵについての入力操作の判定を無効とする。
【００９６】
本実施の形態によれば、入力操作による変化量とほぼ同レベルの消灯時受光量Ｌｏｆｆ（ｃ）の微小変化も拡大してＡ／Ｄコンバータ１９の入力電圧範囲内で読み取るので、外来光などの微小変化を確実に検出でき、特定のスイッチユニットＵが発光時受光量Ｌｏｎの増加から入力操作と誤判定しても、その判定を無効とし、家電機器などで意図しない命令が実行されることを防止できる。
【００９７】
また、発光期間ｔｏｎと消灯期間ｔｏｆｆで、光電変換信号の値が大きく異なるものであっても、それぞれのレベルに合わせた値のオフセット信号がオペアンプ１８の他方の反転入力端子１８ａへ入力されるので、増幅信号は、いずれであってもほぼ設定値近傍の値に安定し、Ａ／Ｄコンバータ１９のリファレンス電圧を越えてオーバーフローすることがなく、確実にＡ／Ｄ変換される。
【００９８】
上述の第１、第２実施の形態において、入力しきい値と環境しきい値は、入力操作状態を最も効果的に判定できるように任意に定められるものであり、上述の例に限るものではない。
【００９９】
また、以上の実施の形態では、光検出信号として赤外光を用い、受光素子６ａの受光面を、赤外光検出信号の赤外線のみを透過させる赤外フィルタ８で覆い、赤外光以外の外来光や内部散乱光が受光素子６ａで受光されることを防止しているが、受光量を比較して入力操作状態が判定できれば、必ずしも、特定波長の光検出信号を用いる必要はない。
【０１００】
更に、Ａ／Ｄコンバータ１９とＤ／Ａコンバータ２０は、それぞれマイコン１０内に含めてもよく、別の回路としてもよい。
【０１０１】
更に、指１１で入力操作を行う例で説明したが、指以外の専用入力ペン等を操作体と入力操作を行うものであってもよい。
【０１０２】
【発明の効果】
以上説明したように、本発明によれば、入力操作による受光量の微小増加分のみを拡大して検出し、これにより正確に入力操作状態を判定することができる。
【０１０３】
また、請求項２の発明によれば、これに加えて、設定値がＡ／Ｄ変換部の入力電圧範囲のほぼ中央に設定されるので、増幅信号の値は、入力電圧のほぼ中央を中心に変動し、光電変換信号の変化をＡ／Ｄ変換部で確実に読み取ることができる。
【０１０４】
また、請求項３の発明によれば、入力操作のタイミングまで、正確に判定できる。
【０１０５】
更に、内部散乱光や外来光の経年変化などによる影響を受けずに入力操作を判定できる。
【０１０６】
また、請求項４の発明によれば、外来光の変化による増加分のみを拡大し、これにより、外来光による受光量の変化を正確に判定し、入力操作と同じように外来光が変化することにより入力操作と誤判定した場合であっても、これを無効とすることができる。
【０１０７】
更に、入力判定手段から出力するオフセット信号の値は、走査周期Ｔの発光期間と消灯期間のそれぞれについて、その期間内に入力される光電変換信号の値に対し設定するので、発光時受光量と消灯時受光量間の値が大きく異なるものであっても、オフセット信号値を大きく設定し直すことなく、速やかに算出できる。
【図面の簡単な説明】
【図１】本発明に係る操作パネル入力装置１の斜視図である。
【図２】操作パネル入力装置１の縦断面図である。
【図３】図２の要部拡大縦断面図である。
【図４】操作パネル入力装置１の構成を示すブロック図である。
【図５】操作パネル入力装置１の要部構成を示すブロック図である。
【図６】操作パネル入力装置１の各光スイッチユニットＵから発光される赤外光検出信号を示すタイミングチャートである。
【図７】発光期間ｔｏｎと消灯期間ｔｏｆｆ内に、受光量を読み込むタイミングを示すタイミングチャートである。
【図８】特定のスイッチユニットＵに対して、指１１を接近させた後離間させる入力操作状態において、発光時受光量Ｌｏｎと消灯時受光量Ｌｏｆｆの変化を表したグラフである。
【図９】従来の操作パネル入力装置１００を示す縦断面図である。
【図１０】従来の操作パネル入力装置１００の光スイッチユニットＵから発光される赤外線検出信号のタイミングチャートである。
【図１１】操作パネル入力装置１１０の構成を示すブロック図である。
【符号の説明】
１　　　　操作パネル入力装置
３　　　　操作パネル（透明アクリル板）
５ａ　　　発光手段（赤外発光素子）
６ａ　　　受光手段（赤外受光素子）
１０　　　マイコン（発光制御手段、受光制御手段、入力判定手段）
１８　　　増幅手段（差動増幅回路、オペアンプ）
１８ａ　　反転入力端子
１８ｂ　　非反転入力端子
１８ｃ　　出力端子
１９　　　Ａ／Ｄコンバータ
２０　　　Ｄ／Ａコンバータ
Ｕ　　　　　　　光スイッチユニット
Ｔ　　　　　　　走査周期
Ｌｏｎ　　　　　発光時受光量
Ｌｏｎ（ｃ）　　新たに検出した発光時受光量
Ｌｏｎ（ｏ）　　一次記憶された発光時受光量
ｔｏｎ　　　　　発光期間
ｔｏｆｆ　　　　消灯期間
Ｌｏｆｆ　　　　消灯時受光量
Ｌｏｆｆ（ｃ）　新たに検出した消灯時受光量
Ｌｏｆｆ（ｏ）　一次記憶された消灯時受光量[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention generally relates to an operation panel input device for performing various input operations on home electric appliances, and more particularly, to an operation panel input device capable of performing an input operation without touching an operation panel.
[0002]
[Prior art]
[0003]
2. Description of the Related Art Home appliances such as a water heater and a washing machine are provided with an operation panel on which operation switches for operating these devices are collectively mounted. The operator performs a predetermined operation control on the device by pressing one of the operation switches with a finger.
[0004]
However, since the operation switch is operated by directly pressing the operation switch with a finger, a movable part must be used, and there is a problem in its durability. There is a problem that the aesthetics of the operation panel are impaired.
[0005]
For this reason, a non-contact operation panel input device capable of executing a predetermined operation without directly touching the operation panel with a finger is known (for example, Patent Document 1).
[0006]
[Patent Document 1]
JP 2000-100287 (page 4, FIG. 2)
[0007]
FIG. 9 shows this conventional operation panel input device 100, in which a plurality of sets of optical switch units U are provided inside an operation panel 101 formed of a transparent acrylic plate in accordance with the control content of home electric appliances. ₁ (For example, turning on the power of home appliances), U ₂ ・・ Is arranged.
[0008]
Each set of optical switch units U is 455K _HZ An infrared light emitting element 102 that emits an infrared detection signal having a natural frequency of, and an infrared light receiving element 103 that can receive an infrared detection signal emitted from the infrared light emitting element 102.
[0009]
As shown in FIG. 10, the infrared detection signals emitted from each optical switch unit U are mutually different from each other. ₁ , U ₂ The light is emitted from the infrared light emitting element 102 repeatedly at a predetermined scanning cycle T so as not to overlap with the infrared detection signal emitted from the light emitting element 102.
[0010]
As shown in FIG. 9, the infrared light emitting element 102 and the infrared light receiving element 103 which form a pair in the same optical switch unit U are mounted on a printed wiring board 104 so as to be adjacent to each other. An infrared filter 105 that transmits only infrared light is provided between the operation panels 101.
[0011]
Accordingly, an infrared detection signal emitted from each set of infrared light emitting elements 102 is output to the outside through the infrared filter 105 and the operation panel 101 located above the infrared light detection element 102. Only the infrared ray containing the light passes through the operation panel 101 and the infrared filter 105 in the vicinity and reaches the infrared light receiving element 103.
[0012]
455K on the output side of the infrared light receiving element 103 _HZ And a microcomputer that determines an input operation to the optical switch unit U through a band-pass filter that allows a photoelectric conversion signal having a natural frequency of? Therefore, only when the infrared light receiving element 103 receives the infrared detection signal of the natural frequency, the photoelectric conversion signal is input to the microcomputer. Thereby, the light receiving unit 103 can identify natural light, another remote control transmission signal, and the like, and an infrared detection signal emitted from the infrared light emitting element 102.
[0013]
When there is no object that reflects the infrared detection signal near the optical switch unit U, the infrared detection signal emitted from the infrared light emitting element 102 in a predetermined scanning cycle is transmitted to the pair of the same optical switch unit U. Is not received, and no photoelectric conversion signal is input to the microcomputer. In this state, the microcomputer determines that the input operation on the optical switch unit U has not been performed.
[0014]
On the other hand, the optical switch unit U ₁ When an input operation is performed by, for example, bringing a finger close to the operation panel 101 on which is disposed, the infrared detection signal emitted from the infrared light emitting element 102 is reflected by the finger approaching above the operation panel 101, and the operation is performed again. The same optical switch unit U transmitted through the panel 101 and the infrared filter 105 ₁ Are input to the infrared light receiving element 103. The microcomputer converts the photoelectric conversion signal photoelectrically converted by the infrared light receiving element 103 into the same optical switch unit U. ₁ Of the optical switch unit U when the infrared light emitting element 102 of FIG. ₁ It is determined that an input operation has been performed with respect to, and for example, a control signal for turning on the power is output to the home electric appliance.
[0015]
At this time, the other optical switch units U ₂ Of the infrared light receiving element 103 may receive the infrared detection signal reflected by the finger. ₂ The photoelectric conversion signal is input to the microcomputer at a timing different from the timing at which the infrared light emitting element 102 emits the infrared detection signal. ₂ Is not recognized as an input operation for.
[0016]
By the way, an infrared detection signal reflected by a finger approaching above the operation panel 101, again passing through the operation panel 101 and the infrared filter 105, and input to the infrared light receiving element 103 is weak. The amount of increase in the amount of light received by the infrared light receiving element 103 when the finger is not approached is very small.
[0017]
Therefore, in the operation panel input device 110 shown in FIG. 11, the photoelectric conversion signal obtained by photoelectrically converting the infrared detection signal by the infrared light receiving element 116 is amplified by the amplifier circuit 111 and output to the microcomputer 112 which determines the input operation ( For example, unpublished patent document 1).
[0018]
[Undisclosed patent document 1]
Japanese Patent Application No. 2002-168461 (item
FIG. 3)
That is, the infrared detection signal emitted from the infrared light emitting element 113 and reflected by the finger 114 passes through the transparent operation panel 115 and is received by the infrared light receiving element 116. The infrared light receiving element 116 converts the received infrared detection signal into a photoelectric conversion signal, amplifies it by an amplifier circuit 111 connected to the output side, and outputs the amplified signal to the microcomputer 112 that determines an input operation.
[0020]
[Problems to be solved by the invention]
[0021]
In the operation panel input device 110, all the photoelectric conversion signals representing the amount of light received by the infrared light receiving element 116 are amplified by the amplifying circuit 111. For example, when the microcomputer 112 performs A / D conversion and reads the value, There have been cases where reading cannot be performed because the voltage exceeds the reference voltage.
[0022]
Therefore, the AGC (auto gain) that changes the amplification factor A of the amplifier circuit 111 according to the input level of the photoelectric conversion signal and stabilizes and outputs the level within the reading range of the microcomputer 112 (the input voltage range of the A / D converter). Control) circuit may be used, or a photoelectric conversion signal may be output through a differentiating circuit, and a change may be detected by the microcomputer 112. However, an infrared detection signal reflected by a finger is received. Compared to the slight increase in the photoelectric conversion signal, the infrared light receiving element blinks in each scanning cycle T, or the level change of the photoelectric conversion signal due to the external light changing due to various factors is much larger, In any case, it is difficult to accurately detect only the increase due to the input operation.
[0023]
For this reason, although this type of operation panel input device capable of performing an input operation without directly touching the operation panel is desired, the input operation cannot be accurately determined, and the widespread use of the operation panel has become difficult. It was an obstacle.
[0024]
SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional problem, and an operation panel input device capable of detecting only an increase in the amount of received light due to an input operation in an enlarged manner and thereby accurately determining an input operation. The purpose is to provide.
[0025]
In addition, only the increase due to the change in extraneous light is enlarged, thereby accurately judging a slight change in the amount of received light due to extraneous light. An object of the present invention is to provide an operation panel input device that invalidates the operation panel even when the operation is performed.
[0026]
[Means for Solving the Problems]
[0027]
An operation panel input device according to claim 1, wherein at least a part of the operation panel is a light transmission unit, and light emission is disposed inside the operation panel and emits a light detection signal from the light transmission unit of the operation panel to the outside. Means, and an optical switch unit having a pair of light receiving means capable of receiving a light detection signal reflected outside the light transmitting unit, and a light emitting means of the optical switch unit, at least with a scanning cycle shorter than the input operation time. A light emission control unit that repeatedly emits a light detection signal, and a photoelectric conversion unit that causes a pair of light reception units to detect a light reception amount during a detection period set in a scanning cycle in which the light emission unit emits the light detection signal, and performs photoelectric conversion indicating the light reception amount. Light receiving control means for outputting a signal; amplifying means for amplifying a photoelectric conversion signal output from the light receiving means and outputting an amplified signal; and obtaining an amount of light received by the light receiving means from the amplified signal; A control panel input device and an input determination means for determining an input operation state of knit,
Amplifying means, a photoelectric conversion signal and an offset signal input from a pair of input terminals, amplify at a fixed amplification rate, a differential amplifier circuit configured to output an amplified signal from the output terminal, the input determination means, An offset signal is supplied to one input terminal of the differential amplifier circuit so that the value of the amplified signal input from the differential amplifier circuit for each detection period becomes a preset value in the detection period of the next scanning cycle. The amount of received light is calculated from each value of the amplified signal that is output and input, and the offset signal that is input from one input terminal when the differential amplifier circuit outputs the amplified signal.
[0028]
The offset signal input to one input terminal of the differential amplifier circuit has a constant value when the difference between the offset signal and the photoelectric conversion signal output from the light receiving means is amplified at a fixed amplification factor for each detection period of the scanning cycle. Since the value is output as a certain set value, the value of the amplified signal output from the differential amplifying circuit changes around the set value, and the amount of the change is based on the level change of the photoelectric conversion signal. Is the value amplified by
[0029]
Therefore, a slight increase in the value of the photoelectric conversion signal due to the input operation is amplified and appears in the value of the amplified signal input to the input determination means, while the value of the offset signal input to the differential amplifier circuit at that time. Is calculated from the values of the known amplification factor, offset signal and input amplified signal, and the value of the photoelectric conversion signal by the input operation can be calculated from the output of the input determination means one scanning cycle before. The input operation state can be accurately determined by reading in an enlarged manner.
[0030]
Since this calculation process is performed for each of the detection periods specified in the scanning cycle, the offset signal value is set to be large without including the time when a large change occurs in the value of the photoelectric conversion signal such as the infrared light receiving element blinking. It can be calculated quickly without correction.
[0031]
According to a second aspect of the present invention, there is provided the operation panel input device, wherein the input determination unit performs one of an A / D conversion unit that A / D converts the amplified signal and inputs the amplified signal, and a D / A converted offset signal of one of the differential amplifier circuits. It has a D / A conversion unit that outputs to the input terminal, and a calculation unit that calculates the amount of received light from the amplified signal and the offset signal, which are digital signals. The input voltage range is set substantially at the center of the input voltage range.
[0032]
Since the set value is set to approximately the center of the input voltage of the A / D converter, the value of the amplified signal fluctuates around the center of the input voltage, and the change of the photoelectric conversion signal is reliably detected by the A / D converter. Can be read.
[0033]
Further, in the operation panel input device according to the third aspect, the detection period defined within the scanning cycle is a light emission period (ton) in which the light emitting unit emits the light detection signal, and the light receiving unit detects the light emission period (ton). The light receiving amount during light emission (Lon (c)) is compared with the light receiving amount during light emission (Lon (o)) detected by the light receiving means in at least the light emitting period (ton) one scanning cycle before, and a predetermined input threshold value is obtained. When the number exceeds the threshold, the input operation to the optical switch unit is determined.
[0034]
When the operating tool approaches the optical switch unit U, the number of light detection signals reflected by the operating tool and reaching the light receiving means increases. As a result, the newly detected light-receiving amount at the time of light emission is at least the light-emitting amount at the time of light emission one scanning cycle before. The input determination means reads an amplified signal that amplifies the change in the amount of received light during light emission, and compares the amount of change with a predetermined input threshold value. Can be determined.
[0035]
Further, even if the internal scattered light or the external light fluctuates gradually due to aging, the input operation can be determined without being affected by these fluctuations because it does not appear in the difference in the amount of received light during emission.
[0036]
Further, in the operation panel input device according to the fourth aspect, the detection period defined in the scanning cycle is a light emitting period (ton) in which the light emitting means emits a light detection signal and a light extinguishing period (toff) in which the light detection signal is not emitted. The input determination unit determines that the value of the amplified signal input for each detection period in each of the light emission period (ton) and the light-off period (toff) is equal to the set value set in advance in the detection period of the next scanning cycle. An offset signal is generated so as to output the generated offset signal to one input terminal of the differential amplifier circuit during the detection period in the next scanning cycle, and the light-off means detects the light-off means during the light-off period (toff). The light receiving amount (Loff) is compared with the light receiving amount (Loff (o)) at the time of light-off during the light-off period (toff) at least one scanning cycle before, and exceeds a predetermined environmental threshold value. The determination of the input operation to the optical switch unit, characterized by a disabling period of time.
[0037]
Since the light receiving amount detected by the light receiving unit at the time of turning off does not include the light detection signal, the amount of external light or internal scattered light irrelevant to the input operation appears. Even if the temporary increase in extraneous light or internal scattered light is as small as the increase in the received light amount due to the input operation, the input determination means reads the amplified signal that amplifies the change in the received light amount when the light is turned off. By comparing the amount of change with a predetermined environmental threshold value, it can be regarded as a temporary increase in extraneous light or internal scattered light.
[0038]
Therefore, due to a temporary increase in extraneous light or internal scattered light, the amount of light received at the time of light emission also increases and may be determined to be an input operation. Is invalidated for a certain period, and malfunction of the device due to extraneous light or the like can be prevented.
[0039]
The value of the offset signal output from the input determination means is set for each of the light emitting period and the light extinguishing period of the scanning cycle. It can be calculated quickly without setting the value again.
[0040]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of an operation panel input device 1 according to the present invention will be described with reference to FIGS.
[0041]
FIG. 1 is a perspective view of an operation panel input device 1, which is provided in a water heater (not shown) of a facility attached to a unit bus which is a home electric appliance. The operation panel input device according to the present invention is particularly suitable for a washing machine, a bath water heater and the like that require waterproofness, but is attached to these devices as an input device for controlling other electric devices such as audio equipment and air conditioning equipment. May be provided.
[0042]
The operation panel input device 1 includes a rectangular transparent acrylic plate 3, a liquid crystal display panel 4, a backlight panel 7, a reflection plate 9, and a printed wiring board 13 which are formed from the outside (upper side in FIG. 2). These parts are attached to each other in a stacked state, and are housed in a synthetic resin case 2.
[0043]
The case 2 is composed of a square base 2a that opens outward and a holding cover 2b that fits around the square and has a fixed frame 22 protruding above the square, and mounting screws 23 that are inserted through the flange portions of both. Are integrated.
[0044]
An adhesive, an adhesive, or the like is applied between the case 2 and the transparent acrylic plate 3 so that water droplets, dust, and the like do not enter the operation panel input device 1.
[0045]
By providing a step corresponding to the thickness of the fixing frame 22 around the transparent acrylic plate 3, the surface of the transparent acrylic plate 3 and the surface of the surrounding case 2 are aligned on the same plane.
[0046]
The liquid crystal display panel 4 displays, through the transparent acrylic plate 3, a control content for performing an input operation on the water heater and a predetermined display regarding the operation of the water heater. In the water heater shown in FIG. Displays 30a, 30b, 30c,... Indicating input operations such as input, start of hot water supply operation, selection of refilling, etc. are displayed together with operation areas 30A, 30B, 30C,. Also, in this display, the hot water supply amount 31 to the bathtub and the hot water supply temperature 32 are displayed.
[0047]
The display on the liquid crystal display panel 4 is displayed under the control of a liquid crystal driver (not shown). The position and number of the display 30 indicating the operation area and the input operation, and other displays are determined according to the operation state of the water heater. Variable.
[0048]
The backlight panel 7 illuminates the display of the liquid crystal display panel 4 from inside, and guides backlight light from a backlight light source 40 (see FIG. 3) disposed on an end face thereof to the inside. I have. The backlight panel 7 is formed of a transparent acrylic plate having a diffusion sheet 7A attached to the surface (the surface facing the liquid crystal display panel 4), and the back surface has a reflecting plate 9 having a white facing surface. Is disposed, the backlight emitted from the backlight light source is scattered inside the backlight panel 7 and guided outward. As a result, from the outside of the transparent acrylic plate 3, a specific backlight light source is not confirmed, and it looks as if the entire display background of the liquid crystal display panel 4 is illuminated by the backlight light.
[0049]
In the present embodiment, the backlight panel 7 and the backlight light source 40 are separated by a dividing plate 33 for each operation area 30 so that the back surface of the operation area 30 is illuminated by different light sources.
[0050]
As described above, the surface of the reflection plate 9 is coated with white paint to make the surface facing the backlight panel 7 white, and reflects the backlight light into the backlight panel 7 so as not to escape downward. ing. Since the color of the backlight is white, if the backlight light is colored in a predetermined color, the background of the liquid crystal display panel 4 is visually recognized as having changed to the color. The reflecting plate 9 has an output side small hole 34 formed above (surface side) a light emitting element 5a described later in FIG. 3, and an input side small hole 35 formed above the light receiving element 6a. These small holes 34 and 35 are, for example, small holes having an inner diameter of about 1 to 1.5 mm. Further, since the light path is scattered by the diffusion sheet 7A on the front side of the backlight panel 7, the transparent acrylic plate 3 It is not visible from outside.
[0051]
The optical switch unit U is provided on the printed wiring board 13 attached to the rear side of the reflection plate 9 so as to correspond to each of the operation areas 30A, 30B, 30C,. ₁ , U ₂ , U ₃ Are arranged (see FIG. 4). Each optical switch unit U includes a light emitting unit 5 having an infrared light emitting element 5a and a light receiving unit 6 having an infrared light receiving element 6a capable of receiving an infrared light detection signal emitted from the infrared light emitting element 5a. It is configured as a pair. In the present embodiment, an infrared light emitting diode is used as the infrared light emitting element 5a, and a pin photodiode is used as the infrared light receiving element.
[0052]
As shown in FIG. 3, the infrared light emitting element 5a and the infrared light receiving element 6a of the same optical switch unit U have respective light emitting surfaces in output holes 36 and input holes 37 formed in the printed wiring board 13. It is mounted on the back side of the printed wiring board 13 with its light receiving surface facing. Note that an infrared filter 8 that transmits only infrared light of the infrared light detection signal is formed on the light receiving surface of the infrared light receiving element 6a.
[0053]
The output hole 36 and the input hole 37 have an inner diameter slightly larger than the inner diameter of the output side small hole 34 and the input side small hole 35 of the reflector 9 laminated on the surface side thereof. 35, the infrared light detection signal emitted from the infrared light emitting element 5a of each optical switch unit U passes through the output hole 36 and the output side small hole 34. The light radiated outward from the transparent acrylic plate 3 and received from the outside of the transparent acrylic plate 3 passes through the input side small holes 35 and the input holes 37, and further passes through the infrared filter 8, thereby becoming red. The infrared light including the external light detection signal is input to the infrared light receiving element 6a.
[0054]
FIG. 4 is a block diagram showing a circuit configuration of the operation panel input device 1 according to the present embodiment, and FIG. 5 is a block diagram showing a circuit configuration of a main part thereof. The operation panel input device 1 will be described together with its operation.
[0055]
Each optical switch unit U ₁ , U ₂ , U ₃ Each of the infrared light emitting elements 5a is connected to an LED multiplexer 16 that is connected and controlled by the microcomputer 10, and emits an infrared light detection signal at a light emission timing controlled by the microcomputer 10 acting as light emission control means. That is, as shown in FIG. ₁ , U ₂ , U ₃ The infrared light emitting element 5a emits an infrared light detection signal at a timing that does not overlap with the other infrared light emitting elements 5a during a light emitting period ton of 0.5 msec with an extinguishing period toff of 0.5 msec before and after. During the turn-off period toff before and after, no infrared light detection signal is emitted from any of the infrared light emitting elements 5a.
[0056]
The light emission control is repeated again after the light emission control is performed for all the infrared light emitting elements 5a, and the one scanning cycle T is set to a time shorter than the time required for the input operation. Although the time required for the input operation by the operator varies from person to person, it is empirically estimated that the time is from 50 msec to 200 msec. Here, the time is set to 15 msec which is shorter than 50 msec.
[0057]
On the other hand, each optical switch unit U ₁ , U ₂ , U ₃ The infrared light receiving element 6a, which forms a pair with each of the infrared light emitting elements 5a, is connected to a Pd multiplexer 17 that is connected and controlled by the microcomputer 10, and is detected during a detection period controlled by the microcomputer 10 that also functions as light receiving control means. The received light amount is photoelectrically converted and output.
[0058]
The detection period of the infrared light receiving element 6a is synchronized with the scanning period T for controlling the light emission of the light emitting element 5a forming a pair, and the detection period is set for each infrared light receiving element 6a forming a pair. Here, each switch unit U shown in FIG. ₁ , U ₂ , U ₃ The light emitting period ton during which the pair of infrared light emitting elements 5a emit light is the detection period of each infrared light receiving element 6a.
[0059]
As shown in an enlarged manner in FIG. 5, an operational amplifier 18 which is a differential amplifier circuit having a fixed amplification factor (voltage gain) A (here, A = 30) is connected to the output side of the Pd multiplexer 17. I have. One non-inverting input terminal 18b of the operational amplifier 18 is connected to the output of the Pd multiplexer 17, and the non-inverting input terminal 18b receives the amount of light received during the detection period controlled by the microcomputer 10 of each infrared light receiving element 6a. Is input. The other inverting input terminal 18a is connected to the D / A converter 20 of the microcomputer 10, and receives an offset signal generated by the microcomputer 10 by a method described later and output from the D / A converter 20. ing.
[0060]
Therefore, at the output terminal 18c of the operational amplifier 18, an amplified signal in which the difference between each value of the offset signal and the photoelectric conversion signal is amplified at the amplification factor A appears, and this amplified signal is output to the A / D converter 19 of the microcomputer 10. Is done.
[0061]
The A / D converter 19 converts the input amplified signal into an amplified signal value of binary data and outputs the amplified signal to the arithmetic unit 24 in order to perform arithmetic processing in the microcomputer 10. The A / D converter which converts the input voltage of this into 8-bit binary data is used.
[0062]
Further, the D / A converter 20 converts the offset signal value represented by the 8-bit binary data output from the arithmetic unit 24 into an analog offset signal and outputs the same to the inverting input terminal 18 a of the operational amplifier 18. Here, an offset signal of 0 to 3.3 V is output in accordance with the value of the photoelectric conversion signal that changes from 0 to 3 V.
[0063]
As described above, the infrared light receiving element 6a continuously outputs the photoelectric conversion signal during the light emission period ton controlled by the microcomputer 10, and outputs the offset signal input during the light emission period ton from the output terminal 18c of the operational amplifier 18. The amplified signal obtained by amplifying the difference with the amplification factor A is continuously output. As shown in FIG. 7, the microcomputer 10 performs the interrupt process four times during each light emission period ton (12 in the figure). To 15), an amplified signal value is obtained from the A / D converter 19.
[0064]
The arithmetic unit 24 averages the four amplified signal values read from the A / D converter 19 to obtain the amplified signal value input during the light emission period ton, whereby an error occurs in one detection. Even if it occurs, the influence on the amount of received light that is calculated and reduced is reduced.
[0065]
The value of the offset signal generated by the microcomputer 10 and output from the D / A converter 20 is such that the above-described amplified signal value obtained by averaging is equal to the photoelectric conversion signal of the same level in the light emission period ton of the next scanning cycle T. Is input to the operational amplifier 18, and is set in advance to a specific set value.
[0066]
Here, the set value is set to the median value (1.65 V) of the reference voltage (0, 3.3 V) of the A / D converter 19, and the change in the photoelectric conversion signal is enlarged and appears in the change in the amplified signal. Also, the value of the amplified signal is varied around the center of the reference voltage (0, 3.3 V) to perform A / D conversion over a wide range.
[0067]
For example, each binary data is represented in decimal, and an amplified signal value obtained by newly reading and averaging from the A / D converter 19 is AD (c), which is input to the inverting input terminal 18a when outputting the amplified signal. If the offset value input to the D / A converter 20 to output the offset signal is OF (o) and the set value is 128, the offset signal value OF newly generated and output to the D / A converter 20 (C) is represented by OF (c) = OF (o) + (AD (c) −128) / amplification factor A.
[0068]
The offset signal value OF (c) generated by the arithmetic unit 24 is 8-bit data. The offset signal value OF (c) is newly generated for each light emitting period ton and stored at least until the next light emitting period ton. Stored in the unit 25.
[0069]
The arithmetic unit 24 calculates the amount of light received during light emission Lon (c) of the infrared light receiving element 6a during the light emission period ton by the amplified signal value AD (c) and the offset value OF ( o). That is, if the value of the amplified signal obtained by D / A conversion of the amplified signal value AD (c) is divided by the amplification factor A, and the value of the offset signal obtained by D / A conversion of the offset signal value OF (o) is added, the light emitting period ton is obtained. Then, the value of the photoelectric conversion signal photoelectrically converted by the infrared light receiving element 6a can be calculated, and this calculated value is defined as the light receiving amount during light emission Lon (c) detected by the infrared light receiving element 6a.
[0070]
Since the value of the photoelectric conversion signal obtained by photoelectrically converting the amount of received light differs for each infrared light receiving element 6a, the offset signal value OF (c) is set for each light emitting period ton for each infrared light receiving element 6a. It is stored in the storage unit 25.
[0071]
The detected light-receiving amount Lon (c) during light emission is compared with a light-receiving amount during light emission Lon (o), which will be described later, in the microcomputer 10, and a four-stage shift register 21 connected to the microcomputer 10 for each switch unit U. Is stored at the bottom.
[0072]
Similar processing is performed for each switch unit U. ₁ , U ₂ , U ₃ Is repeated every scanning cycle T, the newly detected light-receiving amount Lon (c) during light emission is stored in the lowermost stage of the shift register 21, and the light-receiving amount stored in each stage is sequentially shifted to the upper stage. It is. As a result, for the specific switch unit U, the received light amount during light emission Lon (o) stored in the uppermost stage of the shift register 21 is 4T time before the detection of a new received light amount for the same switch unit U, that is, 60 msec. It represents the amount of light received previously detected.
[0073]
FIG. 8 shows, with a solid line, the amount of light received during light emission Lon detected by the microcomputer 10 for each scanning cycle T with respect to an input operation state in which the finger 11, which is the operating body, approaches and separates from the specific switch unit U. In conclusion, it is a graph showing a change in the light reception amount Lon during light emission.
[0074]
In the period from T1 to T2 in the drawing, the input device is in a standby state before the input operation, and since the finger 11 is separated from the switch unit U, the infrared light receiving element 6a receives the external light and the infrared light detection signal scattered inside. And the amount of light received during light emission Lon is 1V.
[0075]
When the finger 11 is approached by the input operation from the standby state, the infrared light detection signal reflected by the finger 11 is gradually increased, the light receiving amount Lon during light emission is increased, and T7 which is the closest to the switch unit U is detected. In some cases, a peak of about 1.5 V is reached.
[0076]
Thereafter, when the finger 11 is separated, the reflected infrared light detection signal gradually decreases, the light reception amount Lon during light emission also decreases, and returns to the standby state of about 1 V at T12.
[0077]
In the present embodiment, the input operation state is detected from the light-receiving amount Lon during light emission which changes in accordance with the contact and separation of the finger 11, and the microcomputer 10 newly detects the light-receiving amount during light emission Lon (c). Is compared with the light-receiving amount during light emission Lon (o) stored in the uppermost stage of the shift register 21, and when it exceeds a predetermined input threshold value, here 0.3 V, it is determined that the input operation is performed. I do.
[0078]
For example, in FIG. 8, the light reception amount Lon (c) at the time of light emission at T5 is 1.25 V, and the light reception amount Lon (o) at the light emission before 4T time is 1 V, so that the difference does not exceed the input threshold value. At the next T6, the received light amount during light emission Lon (c) is 1.4 V, and the received light amount during light emission at T2 before 4T time is Lon (o) is 1 V. Is determined.
[0079]
Further, the microcomputer 10 compares the newly detected light-receiving amount Lon (c) during light emission with the light-receiving amount during light emission Lon (o) stored in the uppermost stage of the shift register 21 to obtain a predetermined release threshold value. Here, it is determined that the input operation is canceled when the input voltage is reduced by 0.3 V or more.
[0080]
For example, in FIG. 8, the light receiving amount Lon (c) during light emission at T10 is 1.3 V, and the light receiving amount Lon (o) during light emission before 4T time is 1.4 V. At the following T11, the received light amount Lon (c) during light emission is 1.1V, and the received light amount Lon (o) during light emission at T7 before 4T time is 1.5V. It is determined that the operation has been canceled.
[0081]
The microcomputer 10 determines whether or not the input operation and the cancellation of the input operation are performed by each switch unit U. ₁ , U ₂ , U ₃ Each time, the newly detected light-receiving amount Lon (c) during light emission is compared with the light-receiving amount Lon (o) during light emission read from the shift register 21.
[0082]
When the microcomputer 10 determines that the input operation is for a specific switch unit U, the microcomputer 10 executes the instruction associated with the switch unit U for the water heater. For example, the switch unit U arranged below the operation area 30A displaying the display 30a indicating the input operation of the input of the main power supply ₁ Is determined to be an input operation, the power of the water heater is turned on.
[0083]
According to the present embodiment, since only a slight change of about 0.1 V of the photoelectric conversion signal due to the input operation state is enlarged by the amplifying means 18, there is a large level change of the photoelectric conversion signal due to the blinking of the light emitting element 5a. However, it is possible to read within the input voltage range of the A / D converter 19 and reliably determine the input operation state.
[0084]
Furthermore, since the input operation state of each switch unit U including the timing of the release of the input operation can be determined, another command is output in the determination of the release of the input operation, and the time when the input operation and the release of the input operation are determined is determined. The determination result of the input operation is determined at intervals, and the determination result can be used for various purposes.
[0085]
In addition, even if the level of the light receiving amount Lon at the time of light emission received by the infrared light receiving element 6a gradually changes due to aging or the influence of the external light gradually changing, the input operation or the release of the input operation is performed. Both the received light amount during light emission Lon (c) and the received light amount during light emission Lon (o) to be compared in the determination of the above are affected by the influence, and therefore do not appear in the difference. Can be determined.
[0086]
In the above-described first embodiment, extraneous light or internal scattered light that reaches the infrared light receiving element 6a is caused by various causes such as opening of a curtain in a room, lighting of an illumination, approach of an insect, or the like. It may change temporarily, and if these changes rarely increase in the same manner as a change in the amount of light due to the input operation, there is a possibility that the input operation is erroneously determined.
[0087]
For the purpose of detecting such an erroneous determination state, disabling the determination of the input operation for a certain period of time, and preventing a malfunction of a controlled device such as a home appliance, in the second embodiment described below, In the first embodiment, the microcomputer 10 acting as the light receiving control unit is different from the switch unit U shown in FIG. ₁ , U ₂ , U ₃ In addition to the light emitting period ton in which the infrared light emitting element 5a emits light, the amount of received light is also detected in the light-off period toff immediately before.
[0088]
The details of detecting the amount of received light in the light-off period toff are the same as the detection in the light-emitting period ton. As shown in FIG. 7, the microcomputer 10 performs an interrupt process four times for each light-off period toff (see FIG. 7). 12 to 15), an amplified signal value is obtained from the A / D converter 19.
[0089]
The arithmetic unit 24 averages the four light reception amounts read from the A / D converter 19 during the light-off period toff to obtain a newly detected amplified signal value. The detection of the light-off received light amount Loff (c) from the amplified signal value is the same as the detection of the light-emitting received light amount Lon (c).
[0090]
That is, the value of the offset signal output from the D / A converter 20 is such that the newly detected amplified signal value is the median value of the input voltage range of the A / D converter 19 in the light-off period toff of the next scanning cycle T. (1.65V). This offset value OF (o) is set for each light-off period toff for each infrared light receiving element 6a and stored in the storage unit 25, similarly to the offset value OF (o) stored for the light-emitting period ton.
[0091]
The light-receiving amount Loff (c) at the time of turning off the infrared light receiving element 6a during the turning-off period toff is calculated based on the newly detected amplified signal value AD (c) and the offset value OF (o) before one scanning cycle T read from the storage unit 25. Is calculated from
[0092]
That is, the value of the amplified signal obtained by D / A conversion of the amplified signal value AD (c) is divided by the amplification factor A, the value of the offset signal obtained by D / A conversion of the offset signal value OF (o) is added, and the light-off period toff is added. Then, the value of the photoelectric conversion signal photoelectrically converted by the infrared light receiving element 6a is calculated, and this calculated value is used as the light receiving amount Loff (c) when the infrared light receiving element 6a detects the light.
[0093]
The detected light-off-time received light amount Loff (c) is stored in the lowermost stage of the shift register 21 for each switch unit U in the same manner as the light-receiving-time received light amount Loff (c), and the newly detected light-off-time received light amount Loff ( Each time c) is stored in the lowermost stage of the shift register 21, it is sequentially shifted to the upper stage.
[0094]
In the microcomputer 10, for each of the switch units U, the newly detected off-light reception amount Loff (c) and the off-light reception amount Loff (o) stored in the uppermost stage of the shift register 21, that is, 4T time (60 msec) 3) Compare the previously detected off-light reception amount Loff (o) and detect an abnormal increase in extraneous light and internal scattered light.
[0095]
That is, the newly detected off-light reception amount Loff (c) exceeds a predetermined environmental threshold, here 0.3v, compared to the off-light reception amount Loff (o) detected 4T time before. When the number of the switch units U increases, the external light and the internal scattered light are determined to be abnormally increased, and the determination of the input operation for all the switch units U for a predetermined period (for example, several seconds) is invalidated.
[0096]
According to the present embodiment, a minute change in the light-receiving amount Loff (c) at the time of turning off, which is substantially the same level as the amount of change due to the input operation, is also enlarged and read within the input voltage range of the A / D converter 19. Even if a specific switch unit U is erroneously determined to be an input operation due to an increase in the light receiving amount Lon during light emission, the determination is invalidated and an unintended command is executed in a home appliance or the like. Can be prevented.
[0097]
Further, even if the value of the photoelectric conversion signal is significantly different between the light emitting period ton and the light-off period toff, an offset signal having a value corresponding to each level is input to the other inverting input terminal 18a of the operational amplifier 18. In any case, the amplified signal is stabilized to a value near the set value, and does not overflow beyond the reference voltage of the A / D converter 19, so that the A / D conversion is surely performed.
[0098]
In the above-described first and second embodiments, the input threshold value and the environmental threshold value are arbitrarily determined so that the input operation state can be most effectively determined, and are not limited to the above examples. Absent.
[0099]
Further, in the above embodiment, infrared light is used as the light detection signal, and the light receiving surface of the light receiving element 6a is covered with the infrared filter 8 that transmits only the infrared light of the infrared light detection signal. Although external light and internal scattered light are prevented from being received by the light receiving element 6a, it is not always necessary to use a light detection signal of a specific wavelength as long as the amount of received light can be compared to determine the input operation state.
[0100]
Further, the A / D converter 19 and the D / A converter 20 may be included in the microcomputer 10 or may be separate circuits.
[0101]
Furthermore, although an example in which an input operation is performed with the finger 11 has been described, a dedicated input pen or the like other than the finger may be used to perform an input operation with the operating tool.
[0102]
【The invention's effect】
As described above, according to the present invention, only a small increase in the amount of received light due to an input operation is detected in an enlarged manner, whereby the input operation state can be accurately determined.
[0103]
According to the second aspect of the present invention, in addition to this, the set value is set substantially at the center of the input voltage range of the A / D converter, so that the value of the amplified signal is centered at substantially the center of the input voltage. , And the change in the photoelectric conversion signal can be reliably read by the A / D converter.
[0104]
According to the third aspect of the present invention, it is possible to accurately determine the timing of the input operation.
[0105]
Further, the input operation can be determined without being affected by aging of internal scattered light or external light.
[0106]
According to the fourth aspect of the present invention, only the increase due to the change in the extraneous light is enlarged, whereby the change in the amount of received light due to the extraneous light is accurately determined, and the extraneous light changes in the same manner as the input operation. Therefore, even if the input operation is erroneously determined, the input operation can be invalidated.
[0107]
Further, the value of the offset signal output from the input determination means is set for the value of the photoelectric conversion signal input during each of the light emitting period and the light extinguishing period of the scanning cycle T. Even if the value between the light receiving amounts at the time of turning off greatly differs, the value can be calculated quickly without resetting the offset signal value to a large value.
[Brief description of the drawings]
FIG. 1 is a perspective view of an operation panel input device 1 according to the present invention.
FIG. 2 is a vertical sectional view of the operation panel input device 1.
FIG. 3 is an enlarged vertical sectional view of a main part of FIG. 2;
FIG. 4 is a block diagram showing a configuration of the operation panel input device 1.
FIG. 5 is a block diagram showing a main configuration of the operation panel input device 1.
FIG. 6 is a timing chart showing an infrared light detection signal emitted from each optical switch unit U of the operation panel input device 1.
FIG. 7 is a timing chart showing the timing of reading the amount of received light during a light emission period ton and a light-off period toff.
FIG. 8 is a graph showing a change in a light receiving amount at light emission Lon and a light receiving amount at off time Loff in an input operation state in which a finger 11 approaches and then separates from a specific switch unit U;
FIG. 9 is a longitudinal sectional view showing a conventional operation panel input device 100.
FIG. 10 is a timing chart of an infrared detection signal emitted from the optical switch unit U of the conventional operation panel input device 100.
FIG. 11 is a block diagram showing a configuration of the operation panel input device 110.
[Explanation of symbols]
1 Operation panel input device
3 Operation panel (transparent acrylic board)
5a Light emitting means (infrared light emitting element)
6a Light receiving means (infrared light receiving element)
10. Microcomputer (light emission control means, light reception control means, input determination means)
18 Amplifying means (differential amplifier circuit, operational amplifier)
18a Inverting input terminal
18b Non-inverting input terminal
18c output terminal
19 A / D converter
20 D / A converter
U Optical switch unit
T scan cycle
Received light amount during Lon emission
Lon (c) Newly detected light-receiving amount during light emission
Lon (o) Primary stored light-receiving amount during light emission
ton light emission period
toff turn off period
Loff Light receiving amount when the light is off
Loff (c) Newly detected light-receiving amount at turn-off
Loff (o) Primary stored light receiving amount at the time of turning off

Claims

An operation panel (3) at least a part of which is a light transmitting portion;
A light-emitting means (5a) disposed inside the operation panel (3) for emitting a light detection signal outward from the light transmitting portion of the operation panel (3); and detecting light reflected outside the light transmitting portion. An optical switch unit (U) having a pair of light receiving means (6a) capable of receiving a signal;
A light emission control means (10) for repeatedly emitting a light detection signal to the light emission means (5a) of the optical switch unit (U) at least in a scanning cycle (T) shorter than the input operation time;
During a detection period determined within a scanning period (T) in which the light emitting means (5a) emits a light detection signal, the light receiving means (6a) forming a pair detects the amount of received light and outputs a photoelectric conversion signal representing the amount of received light. Light receiving control means (10) for causing
Amplifying means (18) for amplifying the photoelectric conversion signal output from the light receiving means (6a) and outputting an amplified signal;
An input determining means (10) for determining a light receiving amount detected by the light receiving means (6a) from the amplified signal and determining an input operation state with respect to the optical switch unit (U);
The amplification means (18) amplifies the photoelectric conversion signal and the offset signal input from the pair of input terminals (18a, 18b) at a fixed amplification factor (A), and outputs the amplified signal from the output terminal (18c). The differential amplifier circuit,
The input determination means (10) sets the value of the amplified signal input from the differential amplifier circuit (18) for each detection period to a set value preset in the detection period of the next scanning cycle (T). And outputting an offset signal to one input terminal (18b) of the differential amplifier circuit (18).
The amount of received light is calculated from each value of the input amplified signal and the offset signal input from one input terminal (18b) when the differential amplifier circuit (18) outputs the amplified signal. Operation panel input device.

The input determination means (10) includes an A / D converter (19) for A / D-converting the amplified signal and inputting the input signal, and one input terminal (D / A-converted offset signal) of a differential amplifier circuit (18). 18b) a D / A conversion unit (20) for outputting the signal to a digital signal, and a calculation unit (24) for calculating the amount of received light from the amplified signal and the offset signal,
2. The operation panel input device according to claim 1, wherein the set value is set substantially at the center of an input voltage range in which the A / D converter can perform A / D conversion.

The detection period defined within the scanning cycle (T) is a light emission period (ton) in which the light emitting means (5a) emits a light detection signal,
The amount of light received during light emission (Lon (c)) detected by the light receiving means (6a) during the light emitting period (ton) is determined by the light emission detected by the light receiving means (6a) during the light emitting period (ton) at least one scanning cycle (T) earlier. 3. An input operation for an optical switch unit (U) when an increase exceeds a predetermined input threshold value as compared with the hourly received light amount (Lon (o)). Operation panel input device as described.

The detection period defined within the scanning cycle (T) is a light emission period (ton) in which the light emitting means (5a) emits a light detection signal, and a light-off period (toff) in which no light detection signal is emitted.
For each of the light emitting period (ton) and the light-off period (toff), the input determination unit (10) sets in advance the value of the amplified signal input for each detection period in the detection period of the next scanning cycle (T). The offset signal is generated so as to have the set value, and the generated offset signal is output to one input terminal (18b) of the differential amplifier circuit (18) during the detection period of the next scanning cycle (T).
The off-light reception amount (Loff) detected by the light-receiving unit (6a) during the off-period (toff) is calculated based on the off-light reception amount (Loff) detected by the light-receiving unit (6a) at least one scanning cycle (T) earlier. 4. The method according to claim 3, wherein the determination of the input operation on the optical switch unit is invalidated for a predetermined period when the predetermined environmental threshold value is exceeded as compared with (Loff (o)). Operation panel input device.