JP3636792B2

JP3636792B2 - Nib coordinate input device

Info

Publication number: JP3636792B2
Application number: JP29378195A
Authority: JP
Inventors: 隆夫井上; 悦子藤沢; 康弘佐藤
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 1995-10-18
Filing date: 1995-10-18
Publication date: 2005-04-06
Anticipated expiration: 2015-10-18
Also published as: JPH09114586A

Description

【０００１】
【発明の属する技術分野】
この発明はペン先座標入力装置、特にペン先座標入力装置の検出結果の高精度化に関するものである。
【０００２】
【従来の技術】
コンピュ−タと人間のインタ−フェイスとしてはキ−ボ−ド及びマウスが主流である。これらのインターフェイスは図形入力等には使いづらい場合があり、新たなインターフェイスとしてペン先座標入力装置が開発されてきている。
【０００３】
ペン先座標入力装置はタブレット板と組み合わされ使用されていた。ところがタブレット板は多くのスペ−スを必要とし使い勝手が悪い。そこで、特開平6-259187号公報に掲載された入力装置ではペン先の圧力センサが検出した圧力に基づいて入力装置自身の移動方向及び移動量を検出することにより、入力装置自身の位置を検出してペン先座標の入力を行うようにしている。
【０００４】
また、特開平6-230886号公報に掲載されペンシル型座標入力装置では第一の検出位置に取り付けられた一対の加速度センサが筆記面のｘｙ方向の移動量を算出し、第一の検出位置より離れた第二の検出位置に取り付けられた一対の加速度センサで第一の検出位置での検出量との相対移動を検出し、検出した相対移動量からペンの傾斜角度の変化を求め、ペン傾斜角度の変化による移動量の検出誤差を補正している。
【０００５】
【発明が解決しようとする課題】
しかしながら、特開平6-259187号公報に掲載された入力装置では、入力装置の傾斜を考慮していないので、移動量の検出誤差が生じる場合がある。
【０００６】
また、特開平６-230886号公報に掲載されペンシル型座標入力装置では、第一の検出位置に設けた加速度センサと第二の検出位置に設けた加速度センサの検出結果の差からペンシル型座標入力装置の傾斜角度の変化を補正しているが、ペンシル型座標入力装置の傾斜角度が一定である場合には補正が不十分となる。
【０００７】
さらに、装置の傾斜角度を測定する手段としてジャイロなどが考えられるが、ドリフト等の影響で常に高精度で角度を検出し続けるのは難しい。
【０００８】
また、上記装置では重力加速度が考慮されていないが、実際には筆記面は水平とは限らず、検出精度に誤差が生じる場合がある。
【０００９】
この発明はかかる短所を解消するためになされたものであり、装置の傾斜角度及び傾斜方向等を高精度で検出することで、移動量の検出の高精度化を図ることを目的とする。
【００１０】
【課題を解決するための手段】
この発明に係るペン先座標入力装置は、２次元座標検出手段と作用力検出手段と傾斜検出手段と補正手段を有し、２次元座標検出手段はペン軸をｚ軸とし筆記面上を移動するペン先座標入力装置の移動方向及び移動量のｚ軸に直交するｘ軸及びｙ軸の成分を検出し、作用力検出手段はペン先部におけるｚ軸、ｘ軸及びｙ軸の各方向の作用力を検出し、傾斜検出手段は作用力検出手段が検出した作用力を基にペン先座標入力装置の傾斜方向及び傾斜角度を検出し、補正手段は傾斜検出手段が検出したペン先座標入力装置の傾斜方向及び傾斜角度を基に２次元座標検出手段が検出したペン先部のｘｙ平面上の移動方向及び移動量を筆記面上の移動方向及び移動量に補正して、ペン先座標入力装置の傾斜によるペン先部の移動量の検出誤差を少なくする。
【００１１】
さらに、摩擦係数測定手段は筆記面上を筆記面に対して予め定めた角度で移動するペン先座標入力装置のペン先部と筆記面との間の摩擦係数を予め測定し、傾斜検出手段は摩擦係数測定手段が予め測定した摩擦係数と作用力検出手段が検出した作用力を基にペン先座標入力装置の傾斜方向及び傾斜角度を検出して、摩擦抵抗による作用力検出誤差を少なくする。
【００１２】
さらに、摩擦係数測定モードを設定する入力手段を有し、任意のときにペン先部と筆記面との間の摩擦係数を測定できるようにする。
【００１３】
さらに、傾斜検出手段は２次元座標検出手段が検出したペン先部の移動速度が予め定めた一定速度以上のときにペン先座標入力装置の傾斜方向及び傾斜角度を検出して静止摩擦係数による傾斜方向及び傾斜角度の検出誤差を少なくする。
【００１４】
また、傾斜検出手段は２次元座標検出手段が検出したペン先部の移動速度が０になる時点で作用力検出手段が検出したペン先部におけるｚ軸、該ｚ軸と直交するｘ軸及びｙ軸の各方向の作用力を基にペン先座標入力装置の傾斜方向及び傾斜角度を検出して、摩擦抵抗による影響をさらに少なくする。
【００１５】
また、作用力検出手段は筆記面との接触端を回動自在な球体物で構成して、摩擦抵抗を少なくする。
【００１６】
さらに、見積記憶部は球体物に加わる作用力に対応する回転抵抗力の見積り値を予め記憶し、傾斜検出手段は見積記憶部に記憶した回転抵抗力の見積り値と作用力検出手段が検出した作用力を基にペン先座標入力装置の傾斜方向及び傾斜角度を検出して、回転抵抗力の影響によるペン先座標入力装置の傾斜方向及び傾斜角度の検出誤差を少なくする。
【００１７】
【発明の実施の形態】
ペン先座標入力装置ペン先座標入力装置が傾斜した状態で移動すると加速度センサの検出結果は傾斜角度に応じて少なくなる。この発明のペン先座標入力装置は、ペン先座標入力装置の傾斜方向及び傾斜角度を検出し、ペン先座標入力装置の傾斜によるペン先部の移動量の検出誤差を少なくすることにより、筆記面上のペン先部の移動方向及び移動量を正確に検出するものである。なお、以下の説明においてはペン軸をｚ軸としてペン軸と直交する面をｘ軸とｙ軸で表わす。
【００１８】
ペン先座標入力装置は、２次元座標検出手段と作用力検出手段と傾斜検出手段と補正手段を有する。２次元座標検出手段は、例えばペン先部に近い部分に設けた一対の加速度センサと積分手段を備える。加速度センサは筆記面上を移動するペン先座標入力装置のｘ軸方向及びｙ軸方向の加速度成分を検出し、積分手段は加速度センサが検出した加速度を２回積分して筆記面上を移動するペン先座標入力装置のｘ軸方向及びｙ軸方向の移動方向及び移動量を検出する。作用力検出手段はペン先部に、例えばペン先部の全周を覆うように設けられ、ペン先部におけるｚ軸、該ｚ軸と直交するｘ軸及びｙ軸の各方向の作用力を検出する。傾斜検出手段は作用力検出手段が検出した作用力を基にペン先座標入力装置の傾斜方向及び傾斜角度を検出する。補正手段は傾斜検出手段が検出したペン先座標入力装置の傾斜方向及び傾斜角度を基に２次元座標検出手段が検出したペン先部のｘｙ平面上の移動方向及び移動量を筆記面上の移動方向及び移動量に補正して、ペン先座標入力装置の傾斜によるペン先部の移動量の検出誤差を少なくする。
【００１９】
さらに、ペン先座標入力装置は摩擦係数測定手段を有すると良い。例えば筆記面上を筆記面に対して垂直に立てた状態で移動する場合、作用力検出手段が検出した３方向の作用力は筆記面からのｚ軸方向の反力と移動方向と反対方向の摩擦力に分けられる。摩擦係数測定手段は、この反力と摩擦力からペン先座標入力装置のペン先部と筆記面との間の摩擦係数を予め測定する。傾斜検出手段は摩擦係数測定手段が予め測定した摩擦係数と作用力検出手段が検出した作用力を基にペン先座標入力装置の傾斜方向及び傾斜角度を検出して、摩擦抵抗による作用力検出誤差を少なくする。
【００２０】
さらに、摩擦係数測定モードを設定する入力手段を有し、任意のときにペン先部と筆記面との間の摩擦係数を測定できるようにすると良い。
【００２１】
さらに、ペン先部を移動するときの動き初めは移動速度は遅い。ペン先部の移動速度が遅いときは静止摩擦係数のよる影響を受け、摩擦抵抗が大きくなる。このため、傾斜検出手段は２次元座標検出手段が検出したペン先部の移動速度が静止摩擦係数のよる影響が少なくなる予め定めた一定速度以上のときにペン先座標入力装置の傾斜方向及び傾斜角度を検出して、静止摩擦係数による傾斜方向及び傾斜角度の検出誤差を少なくすると検出精度を高めることができる。
【００２２】
また、ペン先部の移動速度が０になる時点では摩擦抵抗力による影響が少ないので、傾斜検出手段は２次元座標検出手段が検出したペン先部の移動速度が０になる時点で作用力検出手段が検出したペン先部に対する作用力を基にペン先座標入力装置の傾斜方向及び傾斜角度を検出して、摩擦抵抗による影響をさらに少なくすることができる。
【００２３】
また、作用力検出手段は筆記面との接触端を回動自在な球体物で構成して、摩擦抵抗を少なくすると良い。
【００２４】
さらに、球体物に加わる作用力に対応する回転抵抗力の見積り値を予め記憶する見積記憶部を有すると好ましい。傾斜検出手段は見積記憶部に記憶した回転抵抗力の見積り値と作用力検出手段が検出した作用力を基にペン先座標入力装置の傾斜方向及び傾斜角度を検出して、回転抵抗力の影響によるペン先座標入力装置の傾斜方向及び傾斜角度の検出誤差を少なくすることができる。
【００２５】
【実施例】
図１はこの発明の一実施例のペン先座標入力装置の側面図で、図２は構成図である。図に示すように、ペン先座標入力装置は２次元座標検出手段としてペン先部７に近い部分に設けた一対の加速度センサ１ａ，１ｂと積分手段３ｃを有し、作用力検出手段として圧力センサ２を有する。また、ペン先座標入力装置は、図２に示すように傾斜検出手段３ａと補正手段３ｂと摩擦係数検出手段３ｄを備える演算部３と見積記憶部４とキャリブレーションスイッチ５を有する。加速度センサ１ａ，１ｂは、例えばペン軸６をｚ軸とした場合のｘ軸方向及びｙ軸方向の加速度を検出するように設けられ、ｘ軸方向及びｙ軸方向の２方向でペン先部７の移動方向及び加速度を検出する。積分手段３ｃは加速度センサ１ａ，１ｂが検出した加速度を短い時間間隔でサンプリングし、時間で２回積分してｘ軸方向及びｙ軸方向の２方向でペン先部７の移動量を検出する。圧力センサ２は、図３に示すようにペン先部７に設けられ、ペン先部７におけるｚ軸、該ｚ軸と直交するｘ軸及びｙ軸の各方向の作用力を検出する。
【００２６】
傾斜検出手段３ａは圧力センサ２が検出した作用力を基にペン先座標入力装置の傾斜方向及び傾斜角度を検出する。例えば圧力センサ２が検出した作用力をベクトルＦで表し、ベクトルＦが図３に示すようにペン軸６に対してαの立体角を持って検出されているとする。もし、このペンが筆記面に対しＦ_Ｎの力で押し当てられていれば、筆記面からは逆にＦ_Ｎの反力を圧力センサ２が受けていることとなる。つまり、この力は筆記面に対し垂直であり、この力の方向を圧力センサ２がペン座標を基準として測定することで現在のペン軸６(ｚ方向)と筆記面との傾斜角θを知ることができる。また、その大きさより現在の筆圧を求まる。もし、筆記面とペン先部７との間の摩擦力を考えなければ、Ｆ＝Ｆ_Ｎ、α＝９０−θとなる。傾斜検出手段３ａは上記のようにして圧力センサ２が検出した作用力を基にペン先座標入力装置の傾斜方向及び傾斜角度を検出する。
【００２７】
ペン先部７は実際には、図４に示すようにμＦ_Ｎの摩擦力を受けているので、さらに摩擦係数検出手段３ｄで予め動摩擦係数μを求め、傾斜検出手段３ａは摩擦係数測定手段３ｄが予め測定した摩擦係数と圧力センサ２が検出した作用力を基にペン先座標入力装置の傾斜方向及び傾斜角度を検出すると良い。なお動摩擦係数μは、Ｆ_Ｎと摩擦力の比で与えられ、ペン先材料と筆記面材料で決まる定数である。
【００２８】
上記動摩擦係数を予め求めには、例えばユーザがキャリブレーションスイッチ５を押して摩擦係数測定するモードを設定して、図４に示すようにペン先座標入力装置を筆記面に対して垂直に立てて移動する。圧力センサ２はｚ軸方向に反力Ｆ_Ｎを検出し、ｚ軸方向と直交する方向にμＦ_Ｎの力を受ける。摩擦係数測定手段３ｄはこの圧力センサ２が測定した力から動摩擦係数μを求め記憶する。
【００２９】
図３に示す場合、摩擦力μＦ_ＮはμＦ_Ｎ＝Ｆ_Ｎtanηとなり、動摩擦係数μはμ＝tanηで表される。また、圧力センサ２が検出した応力Ｆから接触面からの反力|Ｆ_Ｎ|は|Ｆ_Ｎ|＝|Ｆ|cosηとなり、傾斜角θはθ＝90−α＋ηとなり、容易に筆圧とペン傾斜が求まる。なお、簡略化のため図では傾斜方向(ペン軸６を筆記面に投影した場合の方向)と筆記方向(摩擦力の働く方向)は同一軸に乗っていると仮定している。摩擦力方向とペン傾斜方向が同一軸に乗る場合は希であるが、加速度センサ１ａ，１ｂでペン先部７の移動方向を検知しているためこの情報でもって摩擦力の作用方向の検出補正を加えることで立体的な傾斜角検出が可能となる。このように、傾斜検出手段３ａは摩擦係数測定手段３ｄが予め測定した摩擦係数と圧力センサ２が検出した作用力を基にペン先座標入力装置の傾斜方向及び傾斜角度を正確に検出することができる。
【００３０】
補正手段３ｂは傾斜検出手段３ａが検出したペン先座標入力装置の傾斜方向及び傾斜角度を基に加速度センサ１ａ，１ｂ及び積分手段３ｃが検出したペン先部７の移動方向及び移動量を補正して、ペン先座標入力装置の傾斜によるペン先部７の移動量の検出誤差を少なくする。例えば加速度センサ１ａ，１ｂが加速度ａを検出したとすると、筆記面上の加速度ＡはＡ＝ａ／ sin θとなる。このように、ペン先座標入力装置の傾斜及び摩擦力を正確に検出してその影響を補正するので、ペン先座標入力装置の筆記面上での移動方向及び移動距離を正確に検出することができる。
【００３１】
さらに、ペン先部７を移動するとき最初は、移動速度は遅く、ペン先部７の移動速度が遅いときは静止摩擦係数のよる影響を受け摩擦抵抗が大きくなる。例えば、図５（ａ）に示すように一という字を書いた場合、図５（ｂ）に示すような移動方向でペン先座標入力装置を動かしていて、図５（ｃ）に示すように最初はペン先部７の移動速度が上がらず、図５（ｄ）に示すように摩擦力が大きい。これは、静止摩擦係数が作用しているためで、実際の筆記中の動摩擦係数とは区別しなければならない。つまり、ペン先部７の移動速度が上がるまでの状態では摩擦力は不安定であり大きな検出誤差を伴う。そこで、傾斜検出手段３ａは積分手段３ｃが検出したペン先部７の移動速度が静止摩擦係数のよる影響が少なくなる予め定めた一定速度以上のときにペン先座標入力装置の傾斜方向及び傾斜角度を検出して、静止摩擦による傾斜方向及び傾斜角度の検出誤差を少なくするようにしても良い。なお、傾斜検出手段３ａがペン先座標入力装置の傾斜方向及び傾斜角度を検出していないときは、補正手段３ｂは直前に得た傾斜角度で補正を加える。
【００３２】
また、図５の（ｃ）に示すように、ペン先部７の移動速度が０になる時点では摩擦抵抗力による影響が少ないので、傾斜検出手段３ａは積分手段３ｃが検出したペン先部７の移動速度が０になる時点で圧力センサ２が検出したペン先部７におけるｚ軸、該ｚ軸と直交するｘ軸及びｙ軸の各方向の作用力を基にペン先座標入力装置の傾斜方向及び傾斜角度を検出して、摩擦抵抗力による影響をさらに少なくするようにしても良い。この場合、前記の静止摩擦の若干の影響を受けるが、圧力センサ２の検出力の絶対値が極小となる点をサンプリングポイントとすればこの影響も少ない。
【００３３】
また、ペン先座標入力装置は、図６に示すようにペン先部７と筆記面との接触端を回動自在な球体物であるボール８で構成して摩擦抵抗を少なくしても良い。ペン先部７と筆記面との接触端をボール８で構成しない場合は、筆記面の素材に依存する摩擦力により補正を加えることが必要で、被筆記物が異なると新たに摩擦係数を検出しなおす必要があった。先端にボール８を取り付けたことでボール８がスリップしない限り、一定の回転抵抗力しか作用しない。このため、筆記面反力の算出も簡単となり、安定した入力動作ができる。
【００３４】
さらに、ボール８に筆記面とのスリップ防止のために柔らかい部材を用いると、ペン先作用力による回転抵抗変化が大きくなり、いつも一定の回転抵抗値Ｆ_Ｒを想定していると検出誤差を生じてしまう。そのため、見積記憶部４にペン先作用力に対する回転抵抗力の見積り値のテーブルを予め記憶する。傾斜検出手段１ａは圧力センサ２が検出する応力から回転抵抗値力|Ｆ_Ｒ|を求め、ペン先座標入力装置の傾斜方向及び傾斜角度を検出して、回転抵抗力の影響によるペン先座標入力装置の傾斜方向及び傾斜角度の検出誤差を少なくするようにしても良い。
【００３５】
また、ボール８の周囲をインクで覆い、ハウジングとボール８との間の摩擦力を少なくし、筆圧の増加によるによる回転抵抗の増加を少なくしても良い。
【００３６】
【発明の効果】
この発明は以上説明したように、ペン先部におけるｚ軸、該ｚ軸と直交するｘ軸及びｙ軸の各方向の作用力を検出し、検出した作用力を基にペン先座標入力装置の傾斜方向及び傾斜角度を検出し、検出した傾斜方向及び傾斜角度を基に移動量を補正するので、ペン先座標入力装置の傾斜によるペン先部の移動量の検出誤差を少なくすることができる。
【００３７】
さらに、筆記面上を筆記面に対して予め定めた角度で移動するペン先座標入力装置のペン先部と筆記面との間の摩擦係数を予め測定し、予め測定した摩擦係数と検出した作用力を基にペン先座標入力装置の傾斜方向及び傾斜角度を検出するので、ペン先部と筆記面との間の摩擦抵抗力による作用力検出誤差を少なくすることができる。
【００３８】
さらに、任意に摩擦係数を測定するモードを設定することができるので、任意に時点でペン先部と筆記面との間の摩擦係数を測定でき、正確に摩擦係数を測定できる。
【００３９】
さらに、ペン先部の移動速度が予め定めた一定速度以上のときにペン先座標入力装置の傾斜方向及び傾斜角度を検出するので、静止摩擦係数による傾斜方向及び傾斜角度の検出誤差を少なくすることができる。
【００４０】
また、ペン先部の移動速度が０になる時点でペン先部におけるｚ軸、該ｚ軸と直交するｘ軸及びｙ軸の各方向の作用力を基にペン先座標入力装置の傾斜方向及び傾斜角度を検出するので、摩擦抵抗による影響をさらに少なくすることができる。
【００４１】
また、筆記面との接触端を回動自在な球体物で構成するので、筆記面との摩擦抵抗を少なくすることができる。
【００４２】
さらに、予め記憶した球体物に加わる作用力に対する回転抵抗力の見積りとペン先部に対する作用力を基にペン先座標入力装置の傾斜方向及び傾斜角度を検出するので、回転抵抗力の影響によるペン先座標入力装置の傾斜方向及び傾斜角度の検出誤差を少なくすることができる。
【図面の簡単な説明】
【図１】この発明の実施例の側面図である。
【図２】ペン先座標入力装置の構成図である。
【図３】圧力センサの側面図である。
【図４】摩擦係数を測定する場合のペン先座標入力装置の側面図である。
【図５】ペン先部の速度の変化及び摩擦力の変化を示す説明図である。
【図６】ペン先部にボールを用いた場合の側面図である。
【符号の説明】
１加速度センサ
２圧力センサ
３ａ傾斜検出手段
３ｂ補正手段
３ｃ積分手段
３ｄ摩擦係数測定手段
４見積記憶部
５キャリブレーションスイッチ
６ペン軸
７ペン先部
８ボール[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high accuracy of a detection result of a nib coordinate input device, particularly a nib coordinate input device.
[0002]
[Prior art]
A keyboard and a mouse are the mainstream interfaces between computers and humans. These interfaces may be difficult to use for graphic input and the like, and nib coordinate input devices have been developed as new interfaces.
[0003]
The nib coordinate input device was used in combination with a tablet board. However, the tablet board requires a lot of space and is unusable. Therefore, in the input device described in JP-A-6-259187, the position of the input device itself is detected by detecting the direction and amount of movement of the input device based on the pressure detected by the pressure sensor at the pen tip. The pen tip coordinates are then input.
[0004]
Moreover, in the pencil type coordinate input device published in Japanese Patent Laid-Open No. 6-230886, a pair of acceleration sensors attached to the first detection position calculates the movement amount in the xy direction of the writing surface, and from the first detection position A pair of acceleration sensors attached to the second detection position apart from each other detects a relative movement with the detection amount at the first detection position, obtains a change in the tilt angle of the pen from the detected relative movement amount, and tilts the pen The detection error of the movement amount due to the change in angle is corrected.
[0005]
[Problems to be solved by the invention]
However, the input device described in Japanese Patent Application Laid-Open No. 6-259187 does not take into account the inclination of the input device, and thus there may be a movement amount detection error.
[0006]
In the pencil type coordinate input device described in Japanese Patent Laid-Open No. 6-230886, the pencil type coordinate input is performed based on the difference between the detection results of the acceleration sensor provided at the first detection position and the acceleration sensor provided at the second detection position. Although the change in the tilt angle of the device is corrected, the correction becomes insufficient when the tilt angle of the pencil coordinate input device is constant.
[0007]
Further, a gyro or the like can be considered as a means for measuring the tilt angle of the apparatus, but it is difficult to always detect the angle with high accuracy due to the influence of drift or the like.
[0008]
Further, although the gravitational acceleration is not taken into consideration in the above apparatus, the writing surface is not always horizontal, and an error may occur in detection accuracy.
[0009]
The present invention has been made to eliminate such disadvantages, and an object of the present invention is to increase the accuracy of detection of the amount of movement by detecting the inclination angle and the inclination direction of the apparatus with high accuracy.
[0010]
[Means for Solving the Problems]
The pen point coordinate input device according to the present invention has a two-dimensional coordinate detection means, an action force detection means, an inclination detection means, and a correction means, and the two-dimensional coordinate detection means moves on the writing surface with the pen axis as the z-axis. The x-axis and y-axis components orthogonal to the z-axis of the movement direction and amount of movement of the nib coordinate input device are detected, and the action force detecting means operates in the z-axis, x-axis, and y-axis directions at the nib portion . The inclination detection means detects the inclination direction and the inclination angle of the pen tip coordinate input device based on the action force detected by the action force detection means, and the correction means detects the pen tip coordinate input device detected by the inclination detection means. The pen tip coordinate input device corrects the movement direction and movement amount of the pen tip portion on the xy plane detected by the two-dimensional coordinate detection means based on the inclination direction and inclination angle of the writing head to the movement direction and movement amount on the writing surface. Detection error of pen tip movement due to tilt That.
[0011]
Further, the friction coefficient measuring means measures in advance the friction coefficient between the pen tip portion of the pen tip coordinate input device moving on the writing surface at a predetermined angle with respect to the writing surface and the writing surface, and the inclination detecting means is The tilt direction and the tilt angle of the pen tip coordinate input device are detected based on the friction coefficient measured in advance by the friction coefficient measuring means and the acting force detected by the acting force detecting means, thereby reducing the acting force detection error due to the frictional resistance.
[0012]
Furthermore, it has an input means for setting the friction coefficient measurement mode so that the friction coefficient between the pen tip portion and the writing surface can be measured at any time.
[0013]
Further, the tilt detecting means detects the tilt direction and tilt angle of the pen tip coordinate input device when the moving speed of the pen tip detected by the two-dimensional coordinate detecting means is equal to or higher than a predetermined speed, and tilts by a static friction coefficient. to reduce the detection error of the direction and the inclination angle.
[0014]
In addition, the tilt detection means includes a z-axis at the pen tip detected by the acting force detection means when the moving speed of the pen tip detected by the two-dimensional coordinate detection means becomes 0, an x-axis and y orthogonal to the z-axis. By detecting the tilt direction and tilt angle of the pen tip coordinate input device based on the acting force in each direction of the shaft, the influence of frictional resistance is further reduced.
[0015]
In addition, the acting force detecting means is configured by a rotatable spherical object at the contact end with the writing surface to reduce the frictional resistance.
[0016]
Further, the estimated storage unit stores in advance an estimated value of the rotational resistance force corresponding to the acting force applied to the sphere, and the inclination detecting means detects the estimated value of the rotational resistance force stored in the estimated storage unit and the applied force detecting means. The tilt direction and tilt angle of the pen tip coordinate input device are detected based on the acting force, and the detection error of the tilt direction and tilt angle of the pen tip coordinate input device due to the influence of the rotational resistance force is reduced.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
When the nib coordinate input device moves in a tilted state, the detection result of the acceleration sensor decreases according to the tilt angle. The nib coordinate input device of the present invention detects the tilt direction and tilt angle of the nib coordinate input device, and reduces the detection error of the amount of movement of the nib part due to the tilt of the nib coordinate input device. The movement direction and amount of movement of the upper pen tip are accurately detected. In the following description, the plane perpendicular to the pen axis is represented by the x axis and the y axis with the pen axis as the z axis.
[0018]
The pen tip coordinate input device includes a two-dimensional coordinate detection unit, an action force detection unit, an inclination detection unit, and a correction unit. The two-dimensional coordinate detection means includes, for example, a pair of acceleration sensors and integration means provided in a portion close to the pen tip. The acceleration sensor detects acceleration components in the x-axis direction and the y-axis direction of the nib coordinate input device moving on the writing surface, and the integrating means integrates the acceleration detected by the acceleration sensor twice and moves on the writing surface. The movement direction and the movement amount of the pen tip coordinate input device in the x-axis direction and the y-axis direction are detected. The acting force detection means is provided at the pen tip portion so as to cover the entire circumference of the pen tip portion, for example , and detects the acting force in each direction of the z-axis, the x-axis and the y-axis perpendicular to the z-axis at the pen tip portion . To do. The inclination detection means detects the inclination direction and the inclination angle of the pen tip coordinate input device based on the action force detected by the action force detection means. The correcting means moves on the writing surface the moving direction and moving amount of the pen tip portion detected by the two-dimensional coordinate detecting means on the xy plane based on the tilt direction and the tilt angle of the pen tip coordinate input device detected by the tilt detecting means. Correction to the direction and the amount of movement reduces the detection error of the amount of movement of the pen tip due to the inclination of the pen tip coordinate input device.
[0019]
Further, the pen tip coordinate input device preferably has a friction coefficient measuring means. For example, when moving on the writing surface in a state of being perpendicular to the writing surface, the acting force in the three directions detected by the acting force detection means is the reaction force in the z-axis direction from the writing surface and the direction opposite to the moving direction. It can be divided into frictional forces. The friction coefficient measuring means measures in advance a friction coefficient between the pen tip portion of the pen tip coordinate input device and the writing surface from the reaction force and the friction force. The tilt detection means detects the tilt direction and the tilt angle of the nib coordinate input device based on the friction coefficient measured in advance by the friction coefficient measurement means and the action force detected by the action force detection means, and detects an action force detection error due to friction resistance. Reduce.
[0020]
Furthermore, it is preferable to have an input means for setting the friction coefficient measurement mode so that the friction coefficient between the pen tip and the writing surface can be measured at any time.
[0021]
Furthermore, the movement speed is slow at the beginning of movement when moving the pen tip. When the moving speed of the pen tip is slow, the frictional resistance increases due to the influence of the coefficient of static friction. For this reason, the inclination detecting means detects the inclination direction and inclination of the nib coordinate input device when the moving speed of the nib portion detected by the two-dimensional coordinate detecting means is equal to or higher than a predetermined speed at which the influence of the coefficient of static friction is reduced. If the angle is detected and the detection error of the tilt direction and tilt angle due to the static friction coefficient is reduced, the detection accuracy can be increased.
[0022]
Further, since the influence of the frictional resistance is small when the pen tip moving speed becomes zero , the inclination detecting means detects the acting force when the pen tip moving speed detected by the two-dimensional coordinate detecting means becomes zero. By detecting the inclination direction and the inclination angle of the pen tip coordinate input device based on the acting force on the pen tip portion detected by the means, the influence of the frictional resistance can be further reduced.
[0023]
In addition, the acting force detecting means may be configured such that the contact end with the writing surface is formed of a rotatable sphere to reduce the frictional resistance.
[0024]
Furthermore, it is preferable to have an estimated storage unit that stores in advance an estimated value of the rotational resistance corresponding to the acting force applied to the sphere. The tilt detection means detects the tilt direction and tilt angle of the nib coordinate input device based on the estimated value of the rotational resistance stored in the estimated storage unit and the applied force detected by the applied force detection means, and determines the influence of the rotational resistance. The detection error of the tilt direction and tilt angle of the pen tip coordinate input device can be reduced.
[0025]
【Example】
FIG. 1 is a side view of a pen tip coordinate input device according to an embodiment of the present invention, and FIG. 2 is a block diagram. As shown in the figure, the nib coordinate input device has a pair of acceleration sensors 1a and 1b and an integrating unit 3c provided as a two-dimensional coordinate detecting unit near the nib part 7, and a pressure sensor as an acting force detecting unit. 2 Further, as shown in FIG. 2, the pen point coordinate input device includes an arithmetic unit 3, an estimate storage unit 4, and a calibration switch 5 including an inclination detection unit 3a, a correction unit 3b, and a friction coefficient detection unit 3d. The acceleration sensors 1a and 1b are provided so as to detect accelerations in the x-axis direction and the y-axis direction when the pen shaft 6 is the z-axis, for example, and the pen tip portion 7 in two directions of the x-axis direction and the y-axis direction. The moving direction and acceleration of the are detected. The integrating means 3c samples the acceleration detected by the acceleration sensors 1a and 1b at short time intervals, integrates it twice in time, and detects the amount of movement of the pen tip 7 in two directions, the x-axis direction and the y-axis direction. As shown in FIG. 3, the pressure sensor 2 is provided in the pen tip portion 7 and detects an acting force in each direction of the z-axis at the pen tip portion 7 , the x-axis orthogonal to the z-axis, and the y-axis .
[0026]
The tilt detection means 3a detects the tilt direction and tilt angle of the pen tip coordinate input device based on the acting force detected by the pressure sensor 2. For example represent an action force by the pressure sensor 2 is detected by the vector F, and are detected with a solid angle of α vector F is relative to the pen shaft 6 as shown in FIG. If, If this pen is pressed against a force of F _N to the writing surface, so that the pressure sensor 2 a reaction force F _N conversely is received from the writing surface. That is, this force is perpendicular to the writing surface, and the pressure sensor 2 measures the direction of this force on the basis of the pen coordinates, thereby knowing the inclination angle θ between the current pen axis 6 (z direction) and the writing surface. be able to. Also, the current writing pressure is obtained from the size. If the frictional force between the writing surface and the pen tip portion 7 is not considered, F = F _N and α = 90−θ. The tilt detection means 3a detects the tilt direction and tilt angle of the pen tip coordinate input device based on the acting force detected by the pressure sensor 2 as described above.
[0027]
In practice, the pen tip portion 7, so undergoing friction .mu.F _N as shown in FIG. 4, further obtains a pre-dynamic friction coefficient μ in the frictional coefficient detection unit 3d, the inclination detecting means 3a friction coefficient measurement unit 3d It is preferable to detect the inclination direction and the inclination angle of the nib coordinate input device based on the friction coefficient measured in advance and the acting force detected by the pressure sensor 2. The dynamic friction coefficient μ is given by the ratio of _FN and friction force, and is a constant determined by the nib material and the writing surface material.
[0028]
In order to obtain the dynamic friction coefficient in advance, for example, the user presses the calibration switch 5 to set a mode for measuring the friction coefficient, and the pen tip coordinate input device is moved vertically with respect to the writing surface as shown in FIG. To do. The pressure sensor 2 detects a reaction force F _N in the z-axis direction, subjected to a force of .mu.F _N in the direction perpendicular to the z-axis direction. The friction coefficient measuring means 3d calculates and stores the dynamic friction coefficient μ from the force measured by the pressure sensor 2.
[0029]
In the case shown in FIG. 3, the frictional force μF _N is expressed as μF _N = F _N tan η, and the dynamic friction coefficient μ is expressed as μ = tan η. Further, the reaction force | F _N | from the contact surface from the stress F detected by the pressure sensor 2 becomes | F _N | = | F | cos η, and the inclination angle θ becomes θ = 90−α + η. Find the slope. For simplification, in the figure, it is assumed that the inclination direction (direction when the pen shaft 6 is projected onto the writing surface) and the writing direction (direction in which the frictional force is applied) are on the same axis. Although it is rare when the friction force direction and the pen tilt direction are on the same axis, since the movement direction of the pen tip portion 7 is detected by the acceleration sensors 1a and 1b, this information is used to detect and correct the action direction of the friction force. By adding, it becomes possible to detect a three-dimensional inclination angle. In this way, the inclination detecting means 3a can accurately detect the inclination direction and the inclination angle of the pen tip coordinate input device based on the friction coefficient measured in advance by the friction coefficient measuring means 3d and the acting force detected by the pressure sensor 2. it can.
[0030]
The correcting means 3b corrects the moving direction and moving amount of the pen tip portion 7 detected by the acceleration sensors 1a and 1b and the integrating means 3c based on the tilt direction and the tilt angle of the pen tip coordinate input device detected by the tilt detecting means 3a. Thus, the detection error of the movement amount of the pen tip portion 7 due to the inclination of the pen tip coordinate input device is reduced. For example, if the acceleration sensors 1a and 1b detect the acceleration a, the acceleration A on the writing surface is A = a / sin θ . In this way, since the inclination and frictional force of the nib coordinate input device are accurately detected and the influence thereof is corrected, the moving direction and moving distance of the nib coordinate input device on the writing surface can be accurately detected. it can.
[0031]
Further, when the pen tip portion 7 is moved, the moving speed is initially slow, and when the pen tip portion 7 is slow, the frictional resistance increases due to the influence of the static friction coefficient. For example, when the letter “1” is written as shown in FIG. 5A, the pen-tip coordinate input device is moved in the moving direction as shown in FIG. 5B, and as shown in FIG. Initially, the moving speed of the pen tip portion 7 does not increase, and the frictional force is large as shown in FIG. This is because the static friction coefficient is acting, and it must be distinguished from the dynamic friction coefficient in actual writing. In other words, the frictional force is unstable until the moving speed of the pen tip portion 7 is increased, which causes a large detection error. Accordingly, the inclination detecting means 3a is arranged such that the inclination direction and the inclination angle of the nib coordinate input device when the moving speed of the nib portion 7 detected by the integrating means 3c is equal to or higher than a predetermined constant speed at which the influence of the static friction coefficient is reduced. May be detected to reduce the detection error of the tilt direction and tilt angle due to static friction. When the tilt detection means 3a does not detect the tilt direction and tilt angle of the pen tip coordinate input device, the correction means 3b corrects the tilt angle obtained immediately before.
[0032]
Further, as shown in FIG. 5C, since the influence of the frictional resistance is small when the moving speed of the pen tip portion 7 becomes zero, the inclination detecting means 3a detects the pen tip portion 7 detected by the integrating means 3c. The tilt of the pen tip coordinate input device is determined based on the z-axis at the pen tip 7 detected by the pressure sensor 2 when the moving speed of the head becomes zero , and the acting forces in the x-axis and y-axis directions orthogonal to the z-axis. The direction and the inclination angle may be detected to further reduce the influence of the frictional resistance. In this case, the influence of the static friction is slightly affected, but if the point at which the absolute value of the detection force of the pressure sensor 2 is minimized is taken as the sampling point, this influence is small.
[0033]
Further, as shown in FIG. 6, the pen tip coordinate input device may be configured such that the contact end between the pen tip portion 7 and the writing surface is composed of a ball 8 that is a rotatable sphere to reduce frictional resistance. When the contact end between the pen tip portion 7 and the writing surface is not constituted by the ball 8, it is necessary to correct the friction force depending on the material of the writing surface, and a new friction coefficient is detected when the writing object is different. It was necessary to rework. As long as the ball 8 does not slip due to the attachment of the ball 8 to the tip, only a certain rotational resistance acts. For this reason, the calculation of the writing surface reaction force is simplified, and a stable input operation can be performed.
[0034]
Furthermore, the use of soft members for slip prevention of the writing surface to the ball 8, the rotational resistance change due nib acting force is increased, always cause a detection error is assumed constant rotational resistance F _R End up. Therefore, a table of estimated values of the rotational resistance force with respect to the pen tip acting force is stored in the estimated storage unit 4 in advance. The inclination detecting means 1a obtains the rotational resistance value force | F _R | from the stress detected by the pressure sensor 2, detects the inclination direction and the inclination angle of the pen tip coordinate input device, and inputs the pen tip coordinate by the influence of the rotational resistance force. The detection error of the tilt direction and tilt angle of the apparatus may be reduced.
[0035]
Further, the periphery of the ball 8 may be covered with ink, the frictional force between the housing and the ball 8 may be reduced, and the increase in rotational resistance due to an increase in writing pressure may be reduced.
[0036]
【The invention's effect】
As described above, the present invention detects the acting force in each direction of the z-axis at the nib portion , the x-axis and the y-axis orthogonal to the z-axis, and based on the detected acting force, Since the inclination direction and the inclination angle are detected and the movement amount is corrected based on the detected inclination direction and inclination angle, the detection error of the movement amount of the pen tip portion due to the inclination of the pen tip coordinate input device can be reduced.
[0037]
Furthermore, the friction coefficient between the pen tip portion of the pen tip coordinate input device that moves on the writing surface at a predetermined angle with respect to the writing surface and the writing surface is measured in advance, and the pre-measured friction coefficient and the detected action are detected. Since the tilt direction and tilt angle of the pen tip coordinate input device are detected based on the force, it is possible to reduce an action force detection error due to the frictional resistance force between the pen tip portion and the writing surface.
[0038]
Furthermore, since the mode for measuring the friction coefficient can be set arbitrarily, the friction coefficient between the pen tip portion and the writing surface can be measured at any time, and the friction coefficient can be measured accurately.
[0039]
Furthermore, since the tilt direction and tilt angle of the pen tip coordinate input device are detected when the moving speed of the pen tip portion is equal to or higher than a predetermined speed , the detection error of the tilt direction and tilt angle due to the static friction coefficient can be reduced. Can do.
[0040]
Further, when the moving speed of the pen tip portion becomes zero, the tilt direction of the pen tip coordinate input device and the z-axis at the pen tip portion , the x-axis and the y-axis directions orthogonal to the z-axis, and Since the inclination angle is detected, the influence of frictional resistance can be further reduced.
[0041]
Further, since the contact end with the writing surface is formed of a rotatable sphere, the frictional resistance with the writing surface can be reduced.
[0042]
Further, since the tilt direction and the tilt angle of the pen tip coordinate input device are detected based on the estimation of the rotational resistance force against the acting force applied to the spherical object stored in advance and the acting force on the pen tip portion, the pen due to the influence of the rotational resistance force is detected. It is possible to reduce the detection error of the tilt direction and tilt angle of the prior coordinate input device.
[Brief description of the drawings]
FIG. 1 is a side view of an embodiment of the present invention.
FIG. 2 is a configuration diagram of a pen tip coordinate input device.
FIG. 3 is a side view of a pressure sensor.
FIG. 4 is a side view of a nib coordinate input device for measuring a friction coefficient.
FIG. 5 is an explanatory diagram showing changes in the speed of the pen tip portion and changes in frictional force.
FIG. 6 is a side view when a ball is used for the pen tip.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Acceleration sensor 2 Pressure sensor 3a Inclination detection means 3b Correction means 3c Integration means 3d Friction coefficient measurement means 4 Estimate storage part 5 Calibration switch 6 Pen shaft 7 Pen tip part 8 Ball

Claims

In the pen tip coordinate input device that detects the x-axis and y-axis components orthogonal to the z-axis of the movement direction and amount of movement of the pen tip portion with the pen axis moving on the writing surface by the two-dimensional coordinate detection means,
An acting force detecting means for detecting an acting force in each of the z-axis, x-axis, and y-axis directions at the pen tip;
An inclination detection means for detecting an inclination angle and an inclination direction with respect to the writing surface of the pen tip coordinate input device based on the action force detected by the action force detection means;
Based on the tilt direction and tilt angle of the pen tip coordinate input device detected by the tilt detection means, the movement direction and the movement amount of the pen tip portion detected by the two-dimensional coordinate detection means on the xy plane are moved and moved on the writing surface. A nib coordinate input device comprising: correction means for correcting the amount.

Friction coefficient measuring means for measuring in advance a friction coefficient between the pen tip portion of the pen tip coordinate input device that moves on the writing surface at a predetermined angle with respect to the writing surface and the writing surface, and the inclination detecting means is friction 2. The pen tip coordinate input device according to claim 1, wherein the pen tip coordinate input device detects the tilt direction and the tilt angle of the pen tip coordinate input device based on the friction coefficient measured in advance by the coefficient measuring unit and the acting force detected by the acting force detecting unit.

3. The pen point coordinate input device according to claim 2, further comprising an input unit for inputting a setting instruction of a mode for measuring the friction coefficient.

2. The pen tip coordinate according to claim 1, wherein the tilt detecting means detects the tilt direction and the tilt angle of the pen tip coordinate input device when the moving speed of the pen tip portion detected by the two-dimensional coordinate detecting means is equal to or higher than a predetermined speed. Input device.

The tilt detection means is an action force in each of the z-axis, x-axis, and y-axis directions at the pen tip detected by the action force detection means when the moving speed of the pen tip detected by the two-dimensional coordinate detection means becomes zero. The nib coordinate input device according to claim 1, wherein the nib coordinate input device detects an inclination direction and an inclination angle of the nib coordinate input device.

The pen-tip coordinate input device according to claim 1, wherein the contact end with the writing surface is formed of a rotatable spherical object.

An estimated storage unit that stores in advance an estimated value of the rotational resistance corresponding to the acting force applied to the spherical object, and the tilt detecting means is detected by the estimated value of the rotational resistance stored in the estimated storage unit and the applied force detecting means. 7. The pen tip coordinate input device according to claim 6, wherein the tilt direction and the tilt angle of the pen tip coordinate input device are detected based on the acting force.