JP2004341752A - Image reading apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stable image reading apparatus by precisely using a pattern for detecting rotation attached to a roller without increasing manufacturing costs. <P>SOLUTION: A pattern 30 for detecting rotation, in which is formed a plurality of differences on the outer peripheral, is attached over a round on a transparent rotation roller 29 provided in a fingerprint reading part 20. The pattern 30 for detecting rotation and the image of an object brought into contact with the transparent rotation roller 29 are read by a one-dimensional imaging device 24 which is constituted of a plurality of imaging devices. A CPU 10 records the read image based on the change of the image for detecting rotation in regard to the pattern 30 for detecting rotation. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００７９】
ここで、ＭＡＸ（）、ＭＩＮ（）はそれぞれ最大値、最小値を算出する関数である。
【００８０】
次に、ＣＰＵ１０は、最大値ｍａｘ_ａｌｌと最小値ｍｉｎ_ａｌｌをもとに、例えば以下の式（６）によって閾値ｔｈを算出する（ステップＦ２）。
【００８１】
ｔｈ＝（ｍａｘ_ａｌｌ＋ｍｉｎ_ａｌｌ）／２ …（６）
そして、ＣＰＵ１０は、各撮像素子について（ｉ＝０〜Ｎ）、最大値ｍａｘ_ｉが閾値ｔｈよりも大きく、また最小値ｍｉｎ_ｉが閾値ｔｈよりも小さいかを判別する（ステップＦ３〜Ｆ６）。この結果、全ての撮像素子の最大値ｍａｘ_ｉが閾値ｔｈよりも大きく、最小値ｍｉｎ_ｉが閾値ｔｈよりも小さいと判断された場合、補正用データ生成処理により生成された補正用データが適正であると判断する。各撮像素子のばらつきが一定の誤差内に入っているならば、これにより各撮像素子が既に白と黒の両方のデータを読み込んだか否かを判断することができる。
【００８２】
このようにして、補正用データ適正判断処理を実行して、適正ではないと判断された場合には画像の取り込みが実行されないので、安定した状態でのみ画像を取り込んで指紋パターンを生成することができる。
【００８３】
次に、図１５に示すフローチャートを参照しながら横ずれ補正処理ついて説明する。
透明回転ローラ２９は、ローラが回転する構造上、指紋パターンの読み取り時、すなわち被検体である指先が圧接された状態で移動され、回転することにより、左右方向に横ずれを起こす可能性がある。また、透明回転ローラ２９を製造する際に、製造精度にばらつきがある場合も考えられる。そこで透明回転ローラ２９に付した位置補正用パターン３２をもとにして、読み取られた画像に対して、透明回転ローラ２９の横ずれに応じた補正を施す。
【００８４】
ここで、１次元撮像素子２４によって読み取られる位置補正用パターン３２が理想的に読み出されるべき位置をｐ（横ずれが発生していない状態での読取位置）とし、今回読み出された位置補正用パターン３２の位置ｋとの差ｌａｇを読み取り画像の補正に利用する。
【００８５】
例えば、図１６（ａ）に示す１次元撮像素子２４により読み取られた画像例において、理想的に読み出されるべき位置（以下、基準位置と称する）がａ１であり、実際に読み出された位置補正用パターン３２の位置がａ２だった場合には、透明回転ローラ２９の横ずれが発生していないと判別することができる。これに対して、基準位置がｂ１だった場合に、実際にｂ２の位置で位置補正用パターン３２が読み出された場合には、透明回転ローラ２９が右方向にずれていると判断することができる。
【００８６】
図１７には、透明回転ローラ２９上で指紋パターンの読み取りが行われる指紋読み取り範囲と、１次元撮像素子２４との対応関係を示している。図１７に示すように、指紋読み取り範囲は１次元撮像素子２４のＭドットと対応しているものとする。横ずれ補正処理では、差ｌａｇに応じて、１次元撮像素子２４により読み取られたＭドット分の画像をデータを、図１８に示すように、右あるいは左にシフトすることで横ずれを補正する。
【００８７】
ＣＰＵ１０は、Ａ／Ｄ変換回路２８を通じて入力された１次元撮像素子２４によって読み取られた画像データをもとに、位置Ｐと、今回、読み出された位置補正用パターン３２との位置との差を算出する（ステップＧ１）。ここで、差ｌａｇが「０」であった場合には、横ずれが発生していないので横ずれ補正処理を終了する（ステップＧ２、「０」）。
【００８８】
一方、差ｌａｇがマイナスだった場合（ステップＧ２、「−」）、すなわち透明回転ローラ２９が左側にずれていた場合には、補正後の画素の位置ｉをｉ＝Ｍ−１とし（ステップＧ３）、画素位置ｉの画素値ｄａｔａ_ｉを、ｉ−ｌａｇの画素位置の画素値ｄａｔａ_{ｉ−ｌａｇ}とする（ステップＧ４）。すなわち、ずれていた分の画素位置の画素値を、本来の画素位置の画素値にシフトする。
【００８９】
次に、ｉ＝ｉ−１としてｉを更新し（ステップＧ５）、ｉ≦−ｌａｇであった場合には（ステップＧ６、Ｙｅｓ）、さらに処理対象とする画素値が残っているものとして、以下同様にして各画素位置の画素値を差ｌａｇ分、それぞれ右方向にシフトする（ステップＧ４〜Ｇ５）。
【００９０】
こうして、シフトの対象とする各画素位置のシフトが終了すると（ステップＧ６、Ｎｏ）、ｄａｔａ_ｉ＝０とし（ステップＧ７）、０ドットまでの残りの画素位置に対して、ｉ＝ｉ−１としてｉの値を順次更新しながらそれぞれ画素値を０にする（ステップＧ７，Ｇ８，Ｇ９）。
【００９１】
また、差ｌａｇがプラスだった場合（ステップＧ２、「＋」）、すなわち透明回転ローラ２９が右側にずれていた場合には、補正後の画素の位置をｉ＝０とし（ステップＧ１０）、画素値ｉの画素値ｄａｔａ_ｉを、ｉ＋ｌａｇの画素位置の画素値ｄａｔａ_{ｉ＋ｌａｇ}とする（ステップＧ１１）。すなわち、ずれていた分の画素位置の画素値を、本来の画素位置の画素値にシフトする。
【００９２】
次に、ｉ＝ｉ＋１としてｉを更新し（ステップＧ１２）、ｉ＜Ｍ−ｌａｇであった場合には（ステップＧ１３、Ｙｅｓ）、さらに処理対象とする画素値が残っているものとして、以下同様にして各画素位置の画素値を差ｌａｇ分、それぞれ左方向にシフトする（ステップＧ１１，Ｇ１２）。
【００９３】
こうして、シフトの対象とする各画素位置のシフトが終了すると（ステップＧ１３，Ｎｏ）、ｄａｔａ_ｉ＝０とし、Ｎドットまでの残りの画素位置に対して、ｉ＝ｉ＋１としてｉの値を順次更新しながらそれぞれ画素値を０にする（ステップＧ１４，Ｇ１５，Ｇ１６）。
【００９４】
こうして、１次元撮像素子２４により読み取られた画像データを、透明回転ローラ２９の横ずれ分シフトさせる画像処理を施すことにより補正することができる。
【００９５】
なお、図１７のフローチャートに示す横ずれ補正処理だけでなく、補正の指標となる位置ｐを最初の１回または複数回による読み込みで決定することもできる。例えば、１次元撮像素子２４によりｎ回の読み込んだ縦線（位置補正用パターン３２）の位置を｛ｋｉ｜ｉ＝０，１，…，ｎ−１｝とした場合、補正位置ｐは次の式（７）で算出できる。
【００９６】
【数２】

【００９７】
なお、前述した説明では、指紋読み取り範囲（Ｍドット）において読み取られた画像データに対して横ずれ補正をする場合について説明しているが、１次元撮像素子２４のＮ個分の撮像素子に相当する回転検知用パターン（位置補正用パターン３２を含む）の画像データに対しても、同様に横ずれを補正することができる。これにより、透明回転ローラに対する回転検知の精度を向上させることができる。
【００９８】
次に、透明回転ローラ２９に付された回転検知用パターン３０の具体例について説明する。
図１９〜図２１は、透明回転ローラ２９の軸における断面形状が段階的に外径が変化する階段状であり、各段の境界が、軸に対して所定の角度をもった第１の直線部と、軸と平行な第２の直線部とが交互に連続するように（のこぎり歯状となるように）形成されている例を示している（図４において示した回転検知用パターン３０）。図１９は、透明回転ローラ２９の外観構成を示す斜視図、図２０は回転検知用パターン３０と位置補正用パターン３２に相当する部分を平面状に展開して示す図、図２１（ａ）〜（ｄ）は、透明回転ローラ２９の軸における断面図（一方の外表面側のみを示す）である。まず、図２１（ａ）に示す断面形状に形成されているとして説明する。
【００９９】
図２１（ａ）に示すように、透明回転ローラ２９の外周面の表面にそれぞれ外径が異なるＡ面、Ｂ面、Ｃ面、Ｄ面が形成されている。Ａ面、Ｂ面、Ｃ面、Ｄ面のそれぞれは、表面が滑らかないわゆる鏡面に加工される。図２１（ａ）に示す断面形状において、Ｂ面とＣ面、Ｃ面とＤ面のそれぞれの境界（第１の境界、第２の境界）において、のこぎり歯状の同じパターンが形成されている。このパターンには、第１の境界と第２の境界のパターンとが、それぞれの透明回転ローラ２９の軸と平行な部分が一致しないように形成されている。すなわち、パターンの頂点部分が透明回転ローラ２９の軸上で一致しないように、ずらして形成されている。また、Ａ面とＢ面との境界によって、位置補正用パターン３２が形成されている。
【０１００】
具体的な数値を示すと、例えば図２１（ａ）に示すように、透明回転ローラ２９のＡ面部分における外径が７．５ｍｍ、Ａ面部分における透明回転ローラ２９の厚さが０．５ｍｍである。また、図２０に示すように、各段の境界により形成されるパターンの各頂点間の距離は、ローラ径の中心角度で示すと１８°、２つのパターンの頂点間の距離が９°である。また、図２０中に示すα＝０．２１１ｍｍ（５ドット）、β＝１．１８０ｍｍ（２８ドット）、γ＝１．１８０ｍｍ（２８ドット）、δ＝０．４２２ｍｍ（１０ドット）である。なお、図１９〜図２１に示す透明回転ローラ２９の形状は、この数値に限定されるものではない。
【０１０１】
また、図２１（ａ）に示す断面形状では、各段の境界が垂直（ローラの軸に対して垂直）となっているが、図２１（Ｂ）に示すように、各面と境界面との角度が９０°を越えるように形成しても良い。この場合、回転検知用パターン３０及び位置補正用パターン３２の部分の画像を読み取った場合に、パターン部分（線）を境界が垂直に形成された場合よりも太くすることができる。また、境界の段差面を拡散面（１次元撮像素子２４により白と検知される）に形成しても良い。なお、拡散面とは、表面がザラザラしたいわゆるシボ面に形成されており、光が当たった際に拡散（乱反射）させる面である。
【０１０２】
また、図２１（ａ）（ｂ）では、透明回転ローラ２９の端部側の外径が細くなっているが、図２１（ｃ）（ｄ）に示すように、透明回転ローラ２９の端部側の外径が太くＡ面部分の外径が最も細くなるように形成することも可能である。
【０１０３】
ここで、図１９、図２０、図２１（ａ）に示す回転検知用パターン３０が付された透明回転ローラ２９の製造方法の概略について、図２２及び図２３を参照しながら説明する。図２２及び図２３の断面図に示すように、透明回転ローラ２９の製造には、キャビ４０、コア４２、押出ピン４４が用いられる。
【０１０４】
まず、透明回転ローラ２９を製造する際のキャビ４０、コア４２、押出ピン４４の初期状態は、図２２▲１▼に示すようになっている。すなわち、キャビ４０とコア４２とを組み合わせることで、透明回転ローラ２９の形状に合わせた空間が形成されており、この空間内に透明回転ローラ２９の材料（例えばアクリル樹脂）を注入するためのゲート４６とランナー４８が確保されている。
【０１０５】
ここで、図２２▲２▼に示すように、ゲート４６、ランナー４８を通じて、キャビ４０とコア４２により形成された空間内に例えばアクリル樹脂４９が充填される。その後、図２２▲３▼に示すように、樹脂４９が硬化するとキャビ４０が開かれる。この時、透明回転ローラ２９の断面形状が先端部ほど外径を小さい階段状となっているので、キャビ４０を容易に引き抜くことができ、回転検知用パターン３０を精度良く形成することができる。
【０１０６】
次に、図２３▲４▼に示すように、押出ピン４４によってコア４２内の成型品を押し出して、図２３▲５▼に示すように成型品を引き抜く。そして、ゲート、ライナーの部分をカットすることで、透明回転ローラ２９の成型を完了する。
【０１０７】
以上説明した製造方法は、透明回転ローラ２９を大量生産する場合であっても製造コストを大幅に増大させることなく、安定して精度良く回転検知用パターン３０が付すことができる。従って、この製造方法を用いて製造可能な透明回転ローラ２９を用いて画像読み取り装置を構成することで、安定した画像読み取りを実現することができる。
【０１０８】
なお、図２２及び図２３に示す製造方法の例では、透明回転ローラ２９の端部側の外径が細くなっている図２１（ａ）に示す構成を対象としているので、Ａ面とＢとの境界において、キャビ４０とコア４２とを分離させている。回転検知用パターン３０を他の形状とする場合には、その形状に合わせて、キャビ４０とコア４２との分離が容易となる位置に任意に決めることができる。例えば、図２１（ｃ）（ｄ）に示す断面を持つ構成では、Ｃ面とＤ面との境界においてキャビ４０とコア４２とを分離させれば良い。
【０１０９】
また、透明回転ローラ２９に対して拡散面を付加する場合には、その拡散面部分に対応するキャビ４０あるいはコア４２の表面形状を荒らしておく（拡散面としておく）ものとする（図２４、図２７に示す透明回転ローラ２９の例など）。
【０１１０】
以下、他の形状をもった回転検知用パターン３０が付された透明回転ローラ２９の例について説明する。
図２４〜図２６に示す回転検知用パターン３０は、透明回転ローラ２９に設けられたテーパ面上に拡散面（シボ面）を設けて形成された例を示している。
【０１１１】
図２４は、透明回転ローラ２９の外観構成を示す斜視図、図２５は回転検知用パターン３０と位置補正用パターン３２に相当する部分を平面状に展開して示す図、図２６は、透明回転ローラ２９の軸における断面図（一方の外表面側のみを示す）である。
【０１１２】
図２６に示すように、透明回転ローラ２９の外周面には、外径が一定なＡ面の他、先端部の外径を小さくしたテーパ面が形成されている。テーパ面には、Ｂ面、Ｃ面、Ｄ面が形成されている。Ｂ面及びＤ面は鏡面に加工され、Ｂ面とＤ面に挟まれたＣ面は拡散面に加工される。なお、拡散面は、前述した透明回転ローラ２９の製造方法において、キャビ４０あるいはコア４２に拡散面を形成しておくことで、透明回転ローラ２９に対して対応する箇所に付加されるとしているが、追加工によって付加するようにしても良い。図２６に示す断面形状において、Ｂ面とＣ面、Ｃ面とＤ面のそれぞれの境界（第１の境界、第２の境界）において、のこぎり歯状の同じパターンが形成されている。このパターンには、第１の境界と第２の境界のパターンとが、それぞれの透明回転ローラ２９の軸と平行な部分が一致しないように形成されている。すなわち、パターンの頂点部分が透明回転ローラ２９の軸上で一致しないように、ずらして形成されている。また、Ａ面とＢ面との境界によって、位置補正用パターン３２が形成されている。
【０１１３】
具体的な数値を示すと、例えば図２６に示すように、透明回転ローラ２９のＡ面部分における外径が７．５ｍｍ、Ａ面部分における透明回転ローラ２９の厚さが０．５ｍｍである。また、図２５に示すように、Ｃ面（拡散面）との境界により形成されるパターンの各頂点間の距離（ε）は１８°、２つのパターンの頂点間の距離（ζ）が９°である。また、図２５中に示すα＝０．２１１ｍｍ（５ドット）、β＝１．１８０ｍｍ（２８ドット）、γ＝１．１８０ｍｍ（２８ドット）、δ＝０．４２２ｍｍ（１０ドット）である。なお、図２４〜図２６に示す透明回転ローラ２９の形状は、この数値に限定されるものではない。
【０１１４】
図２７〜図２９に示す回転検知用パターン３０は、透明回転ローラ２９の外周面上に拡散面が設けられ、拡散面の境界が透明回転ローラ２９の軸に対して所定の角度をもった第１の直線部と軸と平行な第２の直線部とが交互に連続するように形成されている例を示している。
【０１１５】
図２７は、透明回転ローラ２９の外観構成を示す斜視図、図２８は回転検知用パターン３０と位置補正用パターン３２に相当する部分を平面状に展開して示す図、図２９は、透明回転ローラ２９の軸における断面図（一方の外表面側のみを示す）である。
【０１１６】
図２９に示すように、透明回転ローラ２９の外周面には、Ａ面、Ｂ面、Ｃ面、Ｄ面が形成されている。Ａ面、Ｂ面、及びＤ面は鏡面に加工され、Ｂ面とＤ面に挟まれたＣ面は拡散面に加工される。また、Ａ面とＢ面との境界には、断面形状がＶ字形となっているＶ溝により位置補正用パターン３２が形成がされている。図２６に示す断面形状において、Ｂ面とＣ面、Ｃ面とＤ面のそれぞれの境界（第１の境界、第２の境界）において、のこぎり歯状の同じパターンが形成されている。このパターンには、第１の境界と第２の境界のパターンとが、それぞれの透明回転ローラ２９の軸と平行な部分が一致しないように形成されている。すなわち、パターンの頂点部分が透明回転ローラ２９の軸上で一致しないように、ずらして形成されている。
【０１１７】
具体的な数値を示すと、例えば図２９に示すように、透明回転ローラ２９の各面の外径が７．５ｍｍ、各面部分における透明回転ローラ２９の厚さが０．５ｍｍである。また、図２８に示すように、Ｃ面（拡散面）との境界により形成されるパターンの各頂点間の距離（ε）は１８°、２つのパターンの頂点間の距離（ζ）が９°である。また、図２８中に示すα＝０．２１１ｍｍ（５ドット）、β＝１．１８０ｍｍ（２８ドット）、γ＝１．１８０ｍｍ（２８ドット）、δ＝０．４２２ｍｍ（１０ドット）である。なお、図２７〜図２９に示す透明回転ローラ２９の形状は、この数値に限定されるものではない。
【０１１８】
図３０〜図３２に示す回転検知用パターン３０は、透明回転ローラ２９の軸に平行な所定の長さ（例えば、予め決められた一定の長さ）をもった線部が等間隔で複数形成されている例を示している。
【０１１９】
図３０は、透明回転ローラ２９の外観構成を示す斜視図、図３１は回転検知用パターン３０と位置補正用パターン３２に相当する部分を平面状に展開して示す図、図３２（ａ１）〜（ｂ２）は、透明回転ローラ２９の軸における断面図（一方の外表面側のみを示す）である。
【０１２０】
図３０及び図３１に示すように、透明回転ローラ２９の外周面には、外径が異なるＡ面とＢ面が形成され、例えば表面は滑らかな鏡面に加工されている。Ｂ面には、透明回転ローラ２９の軸に平行な所定の長さをもったＶ溝が等間隔で複数形成されている。Ｖ溝は、透明回転ローラ２９の端部から形成されている。また、Ａ面とＢ面との段差により位置補正用パターン３２が形成されている。
【０１２１】
図３０中のＸで示す部分の透明回転ローラ２９の軸方向から見た断面図を図３２（ａ１）に示している。図３２（ａ１）に示すように、Ｖ溝の溝幅と、Ｖ溝に挟まれたＢ面の幅とが等間隔となるように各Ｖ溝が形成されている。Ｖ溝が形成される間隔（ピッチ）は、透明回転ローラ２９の回転に伴って画像の取り込みを行なうタイミング（解像度）に応じて形成される。例えば、Ｖ溝の部分が１次元撮像素子２４によって明るい部分（すなわち白）として検出され、Ｂ面の部分が暗い部分（すなわち黒）として検出される場合、読み取りタイミングに応じて、回転検知用パターン３０の部分を読み取って得られた回転検知用画像が白、黒、白…に切り替わるように形成される。
【０１２２】
また、図３２（ａ１）中のＸ１線上の断面を図３２（ａ２）に示している。図３２（ａ２）に示す例では、Ａ面の外径の方が大きく形成されている。
【０１２３】
具体的な数値を示すと、例えば図３２に示すように、透明回転ローラ２９のＡ面の外径が７．５ｍｍ、Ａ面部分における透明回転ローラ２９の厚さが０．５ｍｍである。また、図３１に示すように、線部に対する１次元撮像素子２４による読み取り基準位置として、α＝０．８４３ｍｍ（２０ドット）、β＝０．４２２ｍｍ（１０ドット）であり、γ＝０．６３４°（ローラ径の中心角度）である。なお、図３０〜図３２（ａ１）（ａ２）に示す透明回転ローラ２９の形状は、この数値に限定されるものではない。
【０１２４】
なお、図３０及び図３１に示す線部（Ｖ溝、Ｖ凸）は、白と黒とが等間隔のタイミングで検出されるように、透明回転ローラ２９に形成されているが、線部の間隔をより広く形成するようにしても良い（例えば、γ＝１．２８６°）。この場合、線部の間で１次元撮像素子２４による読み取りの際に、連続してＢ面の部分の読み取りが行われるが、位置補正用パターン３２の部分についても同時に読み取られる。すなわち、いかなるタイミングで画像が読み込まれても、その読み取られた画像データ中には白部分と黒部分が存在することになる。このため、前述した補正データ生成処理（図７）、補正用データ適正判断処理を支障無く実行することができる。
【０１２５】
また、図３２（ａ１）（ａ２）では、線部をＶ溝によって形成しているが。図３２（ｂ１）（ｂ２）に示すように、線部をＶ凸（Ｖ形の凸形状）によって形成することも可能である。図３０中のＸで示す部分の透明回転ローラ２９の軸方向から見た断面図を図３２（ｂ１）に示している。図３２（ｂ１）に示すように、Ｖ凸の幅と、Ｖ凸に挟まれたＢ面の幅とが等間隔となるように各Ｖ凸が形成されている。図３２（ｂ１）中のＸ２線上の断面を図３２（ｂ２）に示している。図３２（ｂ２）に示す例では、Ｂ面の外径の方が大きく形成されている。
【０１２６】
こうして、線部をＶ凸によって形成しても、Ｖ溝によって形成した場合と同様にして使用することができる。なお、図３２（ｂ１）（ｂ２）の構成の透明回転ローラ２９を製造する場合、キャビ４０とコア４２とを分離する位置は、例えばＡ面とＢ面との境界とすることで安定した精度の良い製造が可能である。
【０１２７】
図３３〜図３５に示す回転検知用パターン３０は、図３０〜図３２に示す回転検知用パターン３０と同様にして透明回転ローラ２９の軸に平行な所定の長さをもった線部が等間隔で複数形成されるもので、さらに所定数ごとの線部の一端により形成される包絡線が、透明回転ローラ２９の軸に対して所定の角度をもった直線を形成している例を示している。
【０１２８】
図３３は、透明回転ローラ２９の外観構成を示す斜視図、図３４は回転検知用パターン３０と位置補正用パターン３２に相当する部分を平面状に展開して示す図、図３５（ａ１）〜（ｂ２）は、透明回転ローラ２９の軸における断面図（一方の外表面側のみを示す）である。なお、図３３〜図３５に示す回転検知用パターン３０は、図３０〜図３２に示す構成と線部の長さが異なるだけで、他は同様にして構成されるものとして説明を省略する。
【０１２９】
図３３〜図３４に示すように回転検知用パターン３０を形成する線部は、所定本数ごとに線長が順に短くなっており、その包絡線（線部の先端に接する線）が直線を形成している。従って、透明回転ローラ２９に形成される回転検知用パターン３０全体の包絡線はのこぎり歯のように形成される（図３４参照）。
【０１３０】
具体的な数値を示すと、例えば図３５に示すように、透明回転ローラ２９のＡ面の外径が７．５ｍｍ、Ａ面部分における透明回転ローラ２９の厚さが０．５ｍｍである。また、図３４に示すように、線部に対する１次元撮像素子２４による読み取り基準位置としてα＝０．２１１ｍｍ（５ドット）、β＝０．８４３ｍｍ（２０ドット）であり、γ＝０．２１１ｍｍ（５ドット）、δ＝０．６４３°である。なお、図３３〜図３５に示す透明回転ローラ２９の形状は、この数値に限定されるものではない。
【０１３１】
このように、線部が形成される間隔（ピッチ）が読み取り解像度に合わせて決められているため、のこぎり歯の端点においても回転検知用画像をもとに安定して回転を検知することができる。また、線部の包絡線がのこぎり歯を形成しているので、１次元撮像素子２４によって読み取られた線部に該当する部分の長さの変化から、透明回転ローラ２９の回転方向を検知することもできる。
【０１３２】
なお、前述した説明では、本実施形態における画像データ読み取り装置を携帯電話に実装した場合を例にして説明しているが、他の情報機器に実装するようにしても良いし、画像データ読み取り装置として単独で構成されるものであっても良い。画像データ読み取り装置として単独で構成する場合、例えばパーソナルコンピュータや通信機器などの各種情報機器に接続して使用する。画像読み取り装置は、１次元撮像素子２４により読み取られた画像を回転検知用パターン３０の変化に応じたタイミングで記録しておき、情報機器からの要求に応じて出力しても良いし、１次元撮像素子２４により読み取られた画像を逐次情報機器に出力して、情報機器側で回転検知用パターン３０の変化に応じたタイミングで必要な画像（指紋パターンを表す）を記録するようにしても良い。
【０１３３】
また、前述した説明では、指先の画像データである指紋パターンを読み取る場合について説明しているが、掌紋パターンなど他の人体部分のパターンを検出部分に接触させて画像データを読み取る場合など、被検体が軟質物である場合に適用することで効果を得ることができる。
【０１３４】
また、本発明は、前述した実施形態に限定されるものではなく、実施段階ではその要旨を逸脱しない範囲で種々に変形することが可能である。また、前述した実施形態の内容は可能な限り適宜組み合わせて実施しても良い。前述した実施形態には種々の段階の発明が含まれており、開示される複数の構成要件における適宜の組み合わせにより種々の発明が抽出され得る。例えば、実施形態に示される全構成要件から幾つかの構成要件が削除されても、効果が得られるので有れば、この構成要件が削除された構成が発明として抽出され得る。
【０１３５】
【発明の効果】
以上のように本発明によれば、製造コストを増大させることなく精度良くローラに付された回転検知用のパターンを利用して、安定した画像の読み取りを実現することが可能となるものである。
【０１３６】
また、ローラを用いた画像読み取り時におけるローラの左右方向のずれや、ローラの製造精度のばらつきに影響されることなく、安定した画像の読み取りを実現することが可能となるものである。
【図面の簡単な説明】
【図１】本発明の第１実施形態に係わる画像読み取り装置を搭載した携帯電話の電子回路の構成を示すブロック図。
【図２】本実施形態における指紋読み取り部２０が実装された携帯電話の外観例に示す図。
【図３】第１実施形態における指紋読み取り部２０の機構部分の概略構成（側面断面図）を示す図。
【図４】回転検知用パターン３０が付された透明回転ローラ２９の外観を示す斜視図。
【図５】透明回転ローラ２９に付された回転検知用パターン３０と１次元撮像素子２４の撮像素子との対応関係を示す図。
【図６】第１実施形態におけるタイミング判断処理のフローチャートを示す図。
【図７】タイミング判断処理における補正データ生成処理を説明するためのフローチャート。
【図８】タイミング判断処理における回転検知用画像抽出処理を説明するためのフローチャート。
【図９】タイミング判断処理における画像取り込みタイミング判断処理を説明するためのフローチャート。
【図１０】透明回転ローラ２９に付された回転検知用パターン３０をわかりやすくするために平面状に展開して示す図。
【図１１】回転検知用画像中のパターン部分の位置の変化を説明するための図。
【図１２】回転検知用画像中のパターン部分の移動を説明するための図。
【図１３】第２実施形態におけるタイミング判断処理を説明するためのフローチャート。
【図１４】補正用データ適正判断処理のフローチャート。
【図１５】横ずれ補正処理を説明するためのフローチャート。
【図１６】透明回転ローラ２９の横ずれを説明するための図。
【図１７】透明回転ローラ２９上で指紋パターンの読み取りが行われる指紋読み取り範囲と１次元撮像素子２４との対応関係を示す図。
【図１８】横ずれ補正処理により画像データを右あるいは左にシフトする状況を示す図。
【図１９】透明回転ローラ２９の外観構成を示す斜視図。
【図２０】回転検知用パターン３０と位置補正用パターン３２に相当する部分を平面状に展開して示す図。
【図２１】透明回転ローラ２９の軸における断面図。
【図２２】回転検知用パターン３０が付された透明回転ローラ２９の製造方法を説明するための図。
【図２３】回転検知用パターン３０が付された透明回転ローラ２９の製造方法を説明するための図。
【図２４】透明回転ローラ２９の外観構成を示す斜視図。
【図２５】回転検知用パターン３０と位置補正用パターン３２に相当する部分を平面状に展開して示す図。
【図２６】透明回転ローラ２９の軸における断面図。
【図２７】透明回転ローラ２９の外観構成を示す斜視図。
【図２８】回転検知用パターン３０と位置補正用パターン３２に相当する部分を平面状に展開して示す図。
【図２９】透明回転ローラ２９の軸における断面図。
【図３０】透明回転ローラ２９の外観構成を示す斜視図。
【図３１】回転検知用パターン３０と位置補正用パターン３２に相当する部分を平面状に展開して示す図。
【図３２】透明回転ローラ２９の軸における断面図。
【図３３】透明回転ローラ２９の外観構成を示す斜視図。
【図３４】回転検知用パターン３０と位置補正用パターン３２に相当する部分を平面状に展開して示す図。
【図３５】透明回転ローラ２９の軸における断面図。
【符号の説明】
１０…ＣＰＵ
１２…記憶装置
１４…ＲＡＭ
１６…通話ユニット
１８…表示部
１９…キー部
２０…指紋読み取り部
２１…光源
２２…セルフォックレンズ（レンズ光学系）
２４…１次元撮像素子
２６…撮像制御回路
２７…Ａ／Ｄ変換回路
２８…回転検知センサー
２９…透明回転ローラ
３０…回転検知用パターン
３２…位置補正用パターン
４０…キャビ
４２…コア
４４…押出ピン[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image reading device for reading image data such as a fingerprint pattern.
[0002]
[Prior art]
In recent years, as a device for identifying a person, a pattern matching device (image reading device) that reads a fingerprint pattern of a person as image data and executes a matching process on the fingerprint pattern to specify a person has been used. It is becoming.
[0003]
As a mechanism for reading a fingerprint pattern using a conventional one-dimensional image pickup device, a transparent plate is provided in a sensing unit which is a reading position of a fingerprint pattern, and a light source for illumination and a rod lens group (selfoc lens) are provided below the transparent plate. And a structure in which a one-dimensional image sensor is arranged has been considered.
[0004]
On the other hand, an image data reading apparatus using a transparent rotating roller as a mechanism for reading a fingerprint pattern has been proposed (for example, see Patent Document 1). In a reading device using a transparent rotating roller, a fingertip is pressed against the transparent rotating roller and moved, so that a fingerprint image of the pressed portion is read by an image sensor.
[0005]
Further, in the image reading device of Patent Document 1, a print pattern for rotation detection is provided at a predetermined position of the transparent rotating roller, and the image pattern of the print pattern is read together with image data of a fingerprint pattern by an image pickup device, and the rotation detection is performed. An image pattern of a fingerprint pattern to be collated is generated according to the change in the pattern. This eliminates the need for a rotation detection sensor for detecting the timing of reading image data.
[0006]
[Patent Document 1]
Japanese Patent Application No. 2000-330785
[0007]
[Problems to be solved by the invention]
As described above, in the conventional image reading apparatus (Patent Document 1), a print pattern is added to a part of the transparent rotating roller, and the rotation of the roller is detected by reading the print pattern by the image sensor and detecting the rotation of the roller. Although the sensor can be omitted, there are the following problems.
[0008]
For accurate rotation detection, it is necessary to add an accurate print pattern to the transparent rotating roller.However, when the transparent rotating roller for fingerprint pattern detection is small in shape, the manufacturing cost etc. is reduced. Makes it difficult to add an accurate print pattern. In such a case, stable reading of the image may be difficult.
[0009]
Further, in a one-dimensional image sensor (image sensor) in which the image sensors are arranged one-dimensionally, the performance of each image sensor varies, and data for correcting the variation is required in advance. Even if the correction data is prepared, the brightness of the rotation detection pattern portion and the other portions will be affected by changes in the external light and changes in the light source due to a drop in battery voltage, etc. Changes. For this reason, judging whether or not the read image is a portion of the rotation detection pattern based on a predetermined fixed reference value may increase the instability of operation.
[0010]
Further, in Patent Document 1, as the rotation detection pattern, an equal pitch pattern attached in parallel with the rotation axis of the roller is used. In this equal pitch pattern, the position is set in a blank section between the rotation detection patterns. It is not possible to determine, and all the data between the rotation detection patterns is held, and it is possible to grasp the read timing of the data taken in the rotation detection pattern blank section for the first time when the next rotation detection pattern is detected. For this reason, the minimum rotation speed of the roller has to be guaranteed for realization, and a sufficient storage area for storing data taken in a blank section is required.
[0011]
In addition, a triangular wave pattern is used as the rotation detection pattern. However, in this triangular wave pattern, the accuracy at the apex portion is lower than that at the hatched portion due to the necessity of printing on a roller. Further, since oblique lines having symmetrical angles are mixed, the change in the image read from the pattern may represent the same change in the forward rotation and the reverse rotation of the roller, so that it is difficult to detect the rotation direction of the roller. Had become. Further, when the fingertip is pressed against the roller and rotated when reading the fingerprint pattern, lateral displacement may occur in the left-right direction depending on the mounting structure of the roller. Further, when manufacturing the rollers, there may be a case where manufacturing accuracy varies. In such a case, it may be difficult to stably read the fingerprint pattern using the roller.
[0012]
The present invention has been made in view of the above-described problems, and can realize stable reading of an image using a rotation detection pattern attached to a roller with high accuracy without increasing manufacturing cost. It is an object to provide a possible image reading device.
[0013]
Further, the present invention provides an image reading apparatus capable of realizing stable image reading without being affected by a lateral shift of the roller when reading an image using the roller and a variation in manufacturing accuracy of the roller. The purpose is to provide.
[0014]
[Means for Solving the Problems]
The present invention relates to an image reading apparatus for reading an image of a surface of a subject, wherein a transparent rotating roller having a pattern formed by providing a plurality of steps on an outer peripheral surface is provided over one round, and a transparent rotating roller attached to the transparent rotating roller. Imaging means for reading an image of the subject brought into contact with the transparent rotating roller together with the read pattern, and the imaging means for reading the image at a timing corresponding to a change in the rotation detection image corresponding to the portion of the pattern read by the imaging means. Image recording means for recording an image of the sample.
[0015]
According to such a configuration, since a predetermined pattern is formed and provided by providing a plurality of steps on the surface shape with respect to the transparent rotating roller, the roller can be molded by pulling out from the mold. A pattern can be accurately added without increasing the manufacturing cost of the object, whereby an image of the subject can be stably recorded using the rotation detection image corresponding to the added pattern. .
[0016]
The present invention also provides an image reading apparatus for reading an image on the surface of a subject, wherein a transparent rotating roller provided with a pattern formed by providing a diffusion surface for diffusing light on an outer peripheral surface is provided over one circumference; An imaging unit that reads an image of the subject that has come into contact with the transparent rotation roller together with the pattern attached to the rotation roller; and a timing corresponding to a change in a rotation detection image corresponding to the pattern read by the imaging unit. Image recording means for recording an image of the subject.
[0017]
According to such a configuration, a pattern is formed and added to the transparent rotating roller by providing a diffusing surface in the surface shape, so that the roller is pulled out of the mold (or an additional process for forming the diffusing surface). ), It is possible to accurately add a pattern without increasing the manufacturing cost of the transparent rotating roller, and thereby to stably use the rotation detection image corresponding to the added pattern. Thus, an image of the subject can be recorded.
[0018]
According to the present invention, in an image reading apparatus for reading an image of a surface of a subject, a pattern in which a plurality of line portions having a predetermined length parallel to an axis are formed at equal intervals is provided over one round of an outer peripheral surface. Transparent rotating roller, imaging means for reading an image of an object contacted with the transparent rotating roller together with the pattern provided on the transparent rotating roller, and rotation detection corresponding to the pattern read by the imaging means Image recording means for recording the image of the subject at a timing corresponding to a change in the image for use.
[0019]
According to such a configuration, a pattern is formed on the outer surface by a plurality of line portions having a predetermined length parallel to the axis on the outer surface, and the pattern is added. By making the shape or the convex shape, the roller can be molded by drawing out from the mold, so that the pattern can be accurately added without increasing the manufacturing cost for the transparent rotating roller, and thereby the added pattern The image of the subject can be stably recorded using the rotation detection image corresponding to the above.
[0020]
Further, according to the present invention, in an image reading apparatus for reading an image of a surface of a subject, a transparent rotating roller in which an outer peripheral surface pattern perpendicular to an axis is attached to an outer peripheral surface over one round, and the transparent rotating roller is attached to the transparent rotating roller. An imaging unit that reads an image of the subject that has come into contact with the transparent rotating roller together with the pattern, and an image of the subject that is read at a timing corresponding to a change in a rotation detection image corresponding to the pattern read by the imaging unit. Image recording means for recording.
[0021]
According to such a configuration, since the outer peripheral line pattern perpendicular to the axis is provided on the outer peripheral surface of the roller over one round, even if the roller is rotated left and right at the time of reading the image, Image processing for correcting deviation can be performed based on a portion corresponding to the outer peripheral line pattern in the read image, and an image of the subject can be stably recorded.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of an electronic circuit of a mobile phone equipped with the image reading device according to the first embodiment of the present invention. The mobile phone is configured by a computer which reads a program recorded on a recording medium and whose operation is controlled by the read program.
[0023]
The mobile phone shown in FIG. 1 is configured by connecting a CPU 10 to various devices such as a storage device 12, a RAM 14, a communication unit 16, a display unit 18, a key unit 19, and a fingerprint reading unit 20 via a bus. . The fingerprint reading unit 20 reads an image of a fingerprint pattern on the fingertip using the subject as a fingertip of a person.
[0024]
The CPU 10 realizes various functions by executing a program stored in a program area of the RAM 14. The CPU 10 controls the function of the mobile phone, controls reading of the fingerprint pattern image data by the fingerprint reading unit 20, and executes various processes on the image pattern.
The storage device 12 stores programs, data, and the like, and is read and stored in the RAM 14 as needed.
[0025]
The RAM 14 stores programs and various data and is accessed by the CPU 10. The RAM 14 includes various programs for controlling the mobile phone, a processing program for executing processing on image data of a fingerprint pattern read by the fingerprint reading unit 20, and the like. Is stored. When the fingerprint reading unit 20 reads the image data of the fingerprint pattern, the read image data is stored.
[0026]
The call unit 16 is a unit for performing wireless communication as a mobile phone.
The display unit 18 displays various data when executing various functions realized by the CPU 10.
The key section 19 is composed of a plurality of keys including numeric keys for inputting a telephone number and various function keys.
The fingerprint reading unit 20 reads image data representing a fingerprint pattern, and is provided at a position where a fingerprint reading operation is easy, such as an upper front surface, as shown in an example of the appearance of a mobile phone in FIG. The fingerprint reading unit 20 according to the first embodiment includes a light source 21, a lens optical system (Selfoc lens 22), a one-dimensional imaging device 24, an imaging control circuit 26, an A / D conversion circuit 28, and a transparent rotating roller 29. A part of the outer peripheral surface of the transparent rotating roller 29 is exposed to the outside through a slit provided in the housing of the mobile phone. The exposed portion of the transparent rotating roller 29 serves as a fingerprint pattern reading unit. When reading a fingerprint pattern, a fingertip, which is a subject, is pressed against the reading unit, and in this state, the transparent rotating roller 29 is rotated in a predetermined direction (a direction perpendicular to the rotation axis of the transparent rotating roller 29). This is done by being moved. It is sufficient that the slit provided on the surface of the housing has such a width that the user can press the fingertip against the transparent rotating roller 29 to rotate the transparent rotating roller 29. Therefore, in order to read the image of the fingerprint pattern, it is not necessary to secure a reading surface on which the entire fingerprint fits, and the mounting area of the fingerprint reading unit 20 (transparent rotating roller 29) on the housing surface may be small.
[0027]
In the fingerprint reading unit 20, light reflected from a fingertip, which is a subject, which is irradiated from the light source 21 and pressed against (contacts) the reading unit, passes through the transparent rotating roller 29, and is transmitted to the one-dimensional imaging device 24 by the selfoc lens 22. It is collected. Under the control of the imaging control circuit 26, the light condensed via the selfoc lens 22 is photoelectrically converted by the one-dimensional imaging element 24, and further converted by the A / D conversion circuit 28 as image data representing a fingerprint pattern. From the one-dimensional image sensor 24, data is read periodically at a timing of, for example, 20,000 times / second, and the data is buffered in the RAM. The CPU 10 changes the rotation detection image obtained by reading the portion of the rotation detection pattern 30 attached to the transparent rotation roller 29 with respect to the data read by the one-dimensional image sensor 24 (the predetermined value of the line portion). When a shift occurs, the image data is fetched as image data and recorded in the RAM 14 as a fingerprint pattern image.
[0028]
FIG. 3 shows a schematic configuration (side sectional view) of a mechanism portion of the fingerprint reading unit 20.
As shown in FIG. 3, the housing of the mobile phone is provided with a slit along the rotation axis of the transparent rotating roller 29 so that a part of the outer peripheral surface of the transparent rotating roller 29 is exposed as a fingerprint pattern reading unit. ing. The transparent rotating roller 29 is made of a transparent material such as acrylic or glass so as to transmit light, and is mounted so as to rotate by exposing a part of the outer peripheral surface from a slit provided in the housing. . The transparent rotating roller 29 has a hollow inside, and a light source 21 (for example, an LED (Light Emitting Diode)), a lens optical system (the selfoc lens 22), and a one-dimensional image sensor 24 are provided inside the hollow. Is mounted. These imaging function units are mounted so as not to be linked with the rotation of the transparent rotating roller 29.
[0029]
The selfoc lens 22 forms an image of a portion (reading unit) of the transparent rotary roller 29 where the subject is pressed against the one-dimensional image sensor 24. Note that the present invention is not limited to the selfoc lens, and it is possible to use an imaging optical system constituted by a rod lens group.
[0030]
Although not shown, an optical correction element may be mounted between the transparent rotating roller 29 and the selfoc lens 22. The optical correction element is for correcting an optical effect due to the curvature of the transparent rotating roller 29 in a portion where the fingertip as the subject is pressed, that is, a distorted image. For example, a convex lens, specifically, one surface is flat and opposite. The surface is constituted by a cylindrical lens having a convex curved surface, and has a curvature equal to or close to the inner diameter of the transparent rotating roller 29.
[0031]
The one-dimensional imaging device 24 is configured by a CCD line sensor or a CMOS line sensor, and is mounted so that the arrangement of each imaging device is parallel to the rotation axis of the transparent rotating roller 29. The one-dimensional image sensor 24 has, for example, an imaging range corresponding to the length of the transparent rotating roller 29, and stores an image including a rotation detection pattern 30 added to an end (or near the end) of the transparent rotating roller 29 described later. Can be read. By making the transparent rotating roller 29 hollow and mounting the imaging function unit therein, the mounting area of the fingerprint reading unit 20 on the housing surface and the mounting volume in the housing are reduced.
[0032]
The transparent rotating roller 29 has a pattern formed by making the surface shape of the outer peripheral surface non-uniform. FIG. 4 is a perspective view showing the appearance of the transparent rotating roller 29 provided with the rotation detecting pattern 30. In the transparent rotating roller 29 shown in FIG. 4, the cross-sectional shape of the axis of the transparent rotating roller 29 is step-like in which the outer diameter changes stepwise, and the boundary of each step has a predetermined angle (for example, a predetermined angle) with respect to the axis. Rotation detection formed so that a first linear portion having a predetermined fixed angle) and a second linear portion parallel to the axis are alternately continuous, that is, in a saw-tooth shape. Pattern 30 and a position correction pattern 32, which is a continuous outer peripheral line pattern perpendicular to the axis of the transparent rotating roller 29, are provided on the outer peripheral surface over one round. The cross section of the transparent rotating roller 29 in the position correction pattern 32 (outer line pattern) is perpendicular to the axis of the transparent rotating roller 29. The rotation detection pattern 30 shown in FIG. 4 has three stages of different outer diameters, and two boundaries are formed between each stage. The shape formed by the boundaries of each step of the rotation detection pattern 30 is such that the two linear portions (lines parallel to the axis) and the first linear portion (diagonal lines) are simultaneously read by the one-dimensional image sensor 24. Are arranged in such a manner that the read position, that is, the hatched portion at any one of the boundaries in the read direction is the read position (see FIG. 10). The rotation detecting pattern 30 has, for example, a smooth mirror finish on the outer peripheral surface of the transparent rotating roller 29, and the outer peripheral surface portion is detected as a dark portion (that is, black) by the one-dimensional image sensor 24, and a boundary portion, that is, a step portion is provided. Are detected as a bright portion (that is, white) due to irregular reflection of light from the light source 21. The pixel values of the bright part (white) and the dark part (black) detected by the rotation detection pattern 30 are used to generate correction data based on the rotation detection image in a correction data generation process described later. , Black reference value, and white reference value. Further, the position correction pattern 32 is formed by a boundary where the outer diameter of the transparent rotating roller 29 is different from that of the rotation detection pattern 30, and is detected by the one-dimensional image sensor 24 as a bright portion (white). The rotation detecting pattern 30 provided on the transparent rotating roller 29 shown in FIG. 4 is an example, and details thereof will be described later (FIGS. 19 to 22). Further, the rotation detection pattern 30 having another shape will be described with reference to FIG.
[0033]
In FIG. 3, the light source 21 is provided in the hollow of the transparent rotating roller 29, but the light source 21 may be arranged at a rotating shaft position near the end face of the transparent rotating roller 29, for example. By arranging the light source 21 near the end face of the transparent rotating roller 29, the light flux from the light source 21 is taken in using the transparent rotating roller 29 as a light guide, and is irradiated on the fingertip (subject) contacted with the reading unit. The reflected light may be read by the one-dimensional image sensor 24. The light source 21 can be configured by, for example, an LED, a fluorescent tube, a halogen lamp, or the like.
[0034]
FIG. 5 shows the correspondence between the rotation detection pattern 30 provided on the transparent rotating roller 29 and the image sensor of the one-dimensional image sensor 24. As shown in FIG. 5, the one-dimensional image sensor 24 has the entire length of the transparent rotating roller 29 as an imaging range, and the number (N) of image sensors corresponding to the rotation detection pattern 30 and the position correction pattern 32. Is known, and is used in various processes described below.
[0035]
Next, the operation of the image reading apparatus according to the present embodiment will be described.
In the image reading device according to the first embodiment, each image sensor is determined based on the pixel values read by each image sensor (for N pixels shown in FIG. 5) in the rotation detection image portion of the one-dimensional image sensor 24. By determining the reference value (correction data), that is, the threshold value for determining whether a pixel is black or white, an erroneous determination of rotation detection due to a change in the amount of light of the light source 21 due to a change in external light or a decrease in the battery voltage is made. Reduce the number of images to achieve stable image capture.
[0036]
Since the fingerprint reading unit 20 is not provided with a sensor for detecting the rotation of the transparent rotating roller 29, regardless of the presence or absence of the rotation of the transparent rotating roller 29, the fingerprint reading unit 20 is continuously provided at a cycle of, for example, 20000 times / second. Import image data ().
[0037]
The image data read by the one-dimensional image sensor 24 includes a rotation detection image corresponding to the rotation detection pattern 30 added to the transparent rotation roller 29.
[0038]
The CPU 10 detects the rotation of the transparent rotary roller 29 based on the image data read by the one-dimensional image sensor 24 by a timing determination process described later, and detects the rotation of the object necessary for the rotation of the transparent rotary roller 29. Only when it is determined that image data has been input, the image data is stored as fingerprint image data of the subject.
[0039]
FIG. 6 shows a flowchart of the timing determination process in the first embodiment. FIG. 7 is a flowchart for explaining correction data generation processing in the timing determination processing, FIG. 8 is a flowchart for explaining rotation detection image extraction processing in the timing determination processing, and FIG. 9 is an image capture in the timing determination processing. 9 is a flowchart illustrating a timing determination process.
[0040]
When one line of image data is input from the one-dimensional imaging device 24 through the A / D conversion circuit 28, the CPU 10 executes a correction data generation process on the input data, and Correction data for correcting effects such as variations in sensitivity, external light, and changes in the light source are generated (step A1).
[0041]
The correction of the data read by the image sensor can be realized simply by reading the reference white and black data by the image sensor and using the value as the correction data to calculate the input value. For example, when a value when white is read by a certain image sensor is W and a value when black is read is B, and an input value (pixel value) is corrected in a range of 0 to 255, the input value i is a correction value. i ′ can be corrected according to the following equation (1).
[0042]
i ′ = (i−B) / (W−B) * 255 (1)
In the image reading device according to the present embodiment, correction data is generated for a rotation detection image read by an image sensor corresponding to the rotation detection pattern 30. The rotation of the transparent rotating roller 29 allows each image sensor to take in data based on white and black depending on the shape of the rotation detecting pattern 30 formed by the step on the outer peripheral surface.
[0043]
In the correction data generation processing, of the pixel values of each pixel read by each image sensor, the maximum value is recorded as a white reference value and the minimum value is recorded as a black reference value, that is, correction data. As the transparent rotating roller 29 is rotated, data (maximum value, minimum value) to be used as a reference for white and black by each image sensor is captured.
[0044]
FIG. 7 shows a detailed flowchart of the correction data generation process.
Here, N image sensors used for reading the rotation detection image are used, and the maximum value and the minimum value read by each image sensor up to a certain point in time are respectively ｛max _i | 0 ≦ i ≦ n−1}, {min _i | 0 ≦ i ≦ N−1}, and the newly read data for each image sensor is {data _i This shows generation of correction data when | 0 ≦ i ≦ N−1}.
[0045]
The CPU 10 initializes i = 0 to read data (pixel value) read by each image sensor from the rotation detection image read by the one-dimensional image sensor 24 (step B1). Then, the maximum pixel value max read by the i-th image sensor so far _i And the pixel value data of current interest _i (Step B2). As a result, max _i <Data _i , The pixel value data of current interest _i To the new maximum value max _i (Step B3).
[0046]
Also, the minimum pixel value min read by the i-th image sensor up to that time _i And the pixel value data of current interest _i (Step B4). As a result, min _i > Data _i , The pixel value data of current interest _i Is the new minimum value min _i (Step B5).
[0047]
Next, i is updated as i = i + 1 (step B6), and if i <N, and the processing has not been completed for each image sensor corresponding to the rotation detection image (step B8), the same as described above is performed. , The pixel value data read by the next i-th image sensor _i The maximum value max _i , Minimum value min _i Check if you need to update.
[0048]
The above processing is executed for the pixel values read by the image sensors 0 to N−1 read by the one-dimensional image sensor 24.
[0049]
In the correction data generation process, the correction data can be set based on the rotation detection image read by the one-dimensional image sensor 24 in an environment affected by external light, a change in the light source, and the like. In this way, by calculating the correction value i ′ according to the above-described equation (1) based on the correction data (maximum value, minimum value) set for each image sensor, not only the variation of the image sensor but also the It is possible to correct the influence of a change in light or light source.
[0050]
Next, the CPU 10 executes a rotation detection image extraction process (step A2 (FIG. 8)).
In the rotation detection image extraction process, it is determined whether the pixel corresponding to the image sensor is white or black based on the data (pixel value) read by each image sensor. This is to calculate a threshold value for determining white and black from the maximum value and the minimum value of the pixel values that have been read by the image sensor, and determine whether the pixel value is white or black based on this threshold value. Can be realized by determining Here, the average value of the maximum value and the minimum value is set as a threshold, and white and black of each pixel are determined.
[0051]
FIG. 8 shows a detailed flowchart of the rotation detection image extraction process.
First, in order to read data (pixel value) read by each image sensor from the rotation detection image read by the dimensional image sensor 24, i = 0 is initialized (step C1). The maximum value max of the pixel value read in _i And the minimum value min _i Is calculated as the threshold th (step C2), and the threshold th and the i-th pixel value data are calculated. _i (Step C3). As a result, the threshold value th <data _i Is satisfied (step C3, Yes), the pixel is determined to be white (step C4), and the threshold value th ≧ data _i Is satisfied (Step C3, No), the pixel is determined to be black (Step C5).
[0052]
Next, i is updated by setting i = i + 1 (step C6). If i <N, and the processing has not been completed for each image sensor corresponding to the rotation detection image (step C7), the process proceeds as described above. , The pixel value data read by the next i-th image sensor _i Is determined to be white or black.
[0053]
By executing the above processing for the pixel values read by each of the image sensors from 0 to N−1 read by the one-dimensional image sensor 24, the maximum value and the minimum value of each image sensor that have been read so far are obtained. By determining white or black for each pixel based on the average value, a corrected rotation detection image can be obtained.
[0054]
Next, an image capture timing determination process for determining whether or not it is the image capture timing from the rotation detection image is executed (step A3).
[0055]
FIG. 9 shows a detailed flowchart of the image capture timing determination processing.
First, the CPU 10 detects a portion corresponding to a line segment forming the rotation detection pattern 30 from the rotation detection image generated by the rotation detection image extraction process (step D1).
[0056]
Then, the position of the portion detected at the previous image capturing timing is compared with the position of the currently detected portion (step D2). If the position is separated by a predetermined value or more, it is determined that the image capturing timing is reached. (Step D3).
[0057]
Since the line segment (black portion) has a width, the one-dimensional image sensor 24 detects a black portion of a plurality of pixels. In this case, the center of the black pixel column or one end point is compared as a detection position. To Further, the comparison of the detection positions is performed for all combinations when there are a plurality of portions detected at the previous image capturing timing and a plurality of portions detected this time.
[0058]
FIG. 10 is a diagram showing a rotation detecting pattern 30 applied to the transparent rotating roller 29, which is developed in a plane for easy understanding. The one-dimensional image sensor 24 reads an image in parallel with the rotation axis direction with respect to the transparent rotating roller 29, that is, in the horizontal direction in FIG. Therefore, the respective hatched portions of the two boundaries forming the rotation detection pattern 30 are arranged so as to partially overlap each other as shown in the range of the broken lines a and b in FIG. In addition, they are arranged so that oblique lines formed by at least one of the boundaries can be read. Therefore, the rotation detection pattern 30 can be detected at two or one location by one reading by the one-dimensional image sensor 24. The position correction pattern 32 is always read regardless of the rotational position of the transparent rotary roller 29.
[0059]
FIG. 11A shows a rotation detection image read at the previous image capture timing, and corresponds to two portions a1 and a2 corresponding to the rotation detection pattern 30 and the position correction pattern 32. A portion a3 is detected. Here, it is assumed that three portions b1, b2, and b3 are detected this time, as shown in FIG. In this case, the portions a3 and b3 detected on the rightmost side are excluded as comparisons as portions corresponding to the position correction pattern 32, and the remaining combinations of a1, a2, b1, and b2, a1-b1, a1 The positions are compared for each of -b2, a2-b1, and a2-b2.
[0060]
When reading by the one-dimensional image sensor 24, even if a line segment position (corresponding to an end of the line) parallel to the roller axis at one boundary of the rotation detecting pattern 30 is to be read. , The hatched portion at the other boundary is the object to be read at the same time. Therefore, even if the reading accuracy at the line segment position parallel to the axis is low, since the judgment is made based on the combination of all the parts, the reading is performed stably based on the image corresponding to the hatched part of the other boundary read with high accuracy. The rotation of the transparent rotating roller 29 can be detected.
[0061]
As a result, if the smallest difference among all combinations of positions is equal to or greater than a predetermined value and the movement of the position is confirmed (Step D3, Yes), it is determined that it is the image capturing timing. That is, since the transparent rotating roller 29 is rotated in a state where the subject is pressed against and the new portion of the subject is moved to the reading position by the one-dimensional image sensor 24, the image read at this time is replaced with the fingerprint pattern. Capture as an image. On the other hand, if the minimum difference is not equal to or larger than the predetermined value (step D3, No), it is determined that it is not the image capturing timing.
[0062]
In this way, when it is determined by the image capturing timing determination processing that it is the image capturing timing (step E6), the rotation detection image read by the one-dimensional image sensor 24 is recorded as an image representing a fingerprint pattern.
[0063]
On the other hand, if it is determined that it is not the image capturing timing, the read image is discarded.
[0064]
In this manner, the timing of image capture can be determined based on the movement of the position of the portion corresponding to the line segment of the rotation detection pattern 30 of the rotation detection image, and a fingerprint pattern image can be generated. Since the rotation detection image is corrected according to changes in external light or a light source, the image capture timing can be determined stably.
[0065]
Since the rotation detection pattern 30 is formed with a hatched portion having a predetermined angle with respect to the rotation axis of the transparent rotation roller 29, the pattern portion is changed according to the rotation direction of the transparent rotation roller 29 in the previous rotation. It moves right or left with respect to the pattern part in the read rotation detection image. That is, it is possible to determine in which direction to move based on the direction in which the transparent rotating roller 29 is rotated.
[0066]
For example, in the case of the rotation detection pattern 30 shown in FIG. 10, the transparent rotation roller 29 is rotated in the direction B by moving the fingertip shown in FIG. As a result, the pattern portion moves to the left from the position of the pattern portion in the rotation detection image read earlier. Conversely, when the transparent rotating roller 29 is rotated so as to move the finger from the near side to the far side, as shown in FIGS. Moves to the right with respect to the pattern portion (a1 → b1 → c1 → d1).
[0067]
Thereby, the CPU 10 can detect the rotation direction of the transparent rotating roller 29 and determine from the rotation direction whether the fingerprint pattern is read from the lower part or from the upper part (fingertip side). Therefore, when recording the image read at the reading timing, the fingerprint pattern can be sequentially recorded from the lower or upper part of the fingerprint pattern, and the image of the fingerprint pattern can be generated in a predetermined direction (for example, with the fingertip side up). The images read at the image capturing timing may be sequentially recorded, and if it is determined that the image is read from the lower part of the fingerprint pattern, the image may be inverted by 180 ° after reading the entire image. .
[0068]
As described above, in the first embodiment, the maximum value and the minimum value of the pixel values read so far are recorded for each image sensor of the one-dimensional image sensor 24, and the average value of the maximum value and the minimum value is used as a reference. By setting the value and correcting the data detected by the image sensor based on this reference value, it is possible to stably respond to changes in external light and light sources without preparing correction data in advance. The captured image can be captured. As the rotation detection pattern, when the one-dimensional image sensor 24 captures the image, the rotation detection pattern 30 in which the line segments are arranged so as to form an overlapping portion is attached to the transparent rotation roller 29, so that one line Even if the end position of the minute (the straight line portion parallel to the axis of the roller) is the reading position, the middle of the other oblique line portion is the reading position, so that the image capture timing can be determined stably without lowering the accuracy. be able to. In addition, in order to determine the black and white of the read rotation detection image, the average of the maximum value and the minimum value of the pixel values that have been read by each image sensor is used as a reference value, so that the black and white of the pixel can be easily determined. Can be determined.
[0069]
In the above-described first embodiment, white and black are determined using the average value of the maximum value and the minimum value of the pixel values read by the image sensor of the rotation detection image as a reference value. It is also possible to use another method of setting a reference value. For example, in order to exclude an intermediate value, there is a method of determining a color within a predetermined ratio from each of a maximum value and a minimum value as white and black, respectively.
[0070]
For example, assuming that the range of pixel values to be determined as white / black is N% (2N <100) from the maximum value (max) / minimum value (min), the input data d becomes
(D-min) / (max-min) * 100> (100-N) (2)
Is determined to be white,
(D-min) / (max-min) * 100 <N (3)
Is determined to be black.
[0071]
By using such a reference value, a pixel having an intermediate value read by the one-dimensional image sensor 24 can be excluded.
[0072]
In the first embodiment, the rotation detection image including one or two pattern portions corresponding to the line segments of the rotation detection pattern 30 is read by one reading by the one-dimensional imaging element 24. However, the line segments of the rotation detecting pattern 30 may be arranged so that three or more pattern portions are read. In this case, in the same manner as described above, the change of the detection position is determined for each combination of the previously read pattern portion and the currently read pattern portion, and the read timing is determined.
[0073]
Next, a second embodiment of the present invention will be described.
In the second embodiment, it is possible to determine whether or not the rotation detection of the transparent rotating roller 29 is in an unstable state by using the correction data created by the same processing as the first embodiment. To
[0074]
FIG. 13 is a flowchart illustrating a timing determination process according to the second embodiment. Steps E1, E4, E5, E6, and E7 shown in FIG. 13 execute the same processes as steps A1, A2, A3, A4, and A5 shown in FIG. 6, respectively, and a detailed description thereof will be omitted.
[0075]
After generating the correction data for each of the image sensors of the one-dimensional image sensor 24 by the correction data generation process in step E1, a correction data appropriateness determination process is performed on the correction data (step E2). When it is determined that the correction data is appropriate by the correction data appropriateness determination processing, the subsequent processing is executed.
[0076]
Here, that the correction data is appropriate means that each image sensor reads both white and black data and generates correction data based on the data.
[0077]
FIG. 14 shows a flowchart of the correction data appropriateness determination processing.
The CPU 10 calculates the maximum value max from among the maximum value and the minimum value of the pixel values read so far for each image sensor recorded in the RAM 14. _all , Minimum value min _all Is detected (step F1).
[0078]
(Equation 1)

[0079]
Here, MAX () and MIN () are functions for calculating the maximum value and the minimum value, respectively.
[0080]
Next, the CPU 10 determines the maximum value max. _all And the minimum value min _all , The threshold th is calculated by, for example, the following equation (6) (step F2).
[0081]
th = (max _all + Min _all ) / 2… (6)
Then, the CPU 10 sets the maximum value max for each image sensor (i = 0 to N). _i Is larger than the threshold value th and the minimum value min _i Is smaller than the threshold th (steps F3 to F6). As a result, the maximum value max of all the imaging elements _i Is larger than the threshold th and the minimum value min _i Is smaller than the threshold th, it is determined that the correction data generated by the correction data generation process is appropriate. If the variation of each image sensor is within a certain error, it is possible to determine whether each image sensor has already read both white and black data.
[0082]
In this manner, the correction data appropriateness determination process is performed, and if it is determined that the data is not appropriate, the image capture is not performed. Therefore, it is possible to capture the image only in a stable state and generate the fingerprint pattern. it can.
[0083]
Next, the lateral shift correction processing will be described with reference to the flowchart shown in FIG.
Due to the structure in which the roller rotates, the transparent rotating roller 29 may move laterally when reading a fingerprint pattern, that is, when it is moved while the fingertip, which is the subject, is in pressure contact with it and rotates. Further, when manufacturing the transparent rotating roller 29, there may be a case where manufacturing accuracy varies. Therefore, based on the position correction pattern 32 applied to the transparent rotating roller 29, the read image is corrected according to the lateral displacement of the transparent rotating roller 29.
[0084]
Here, the position at which the position correction pattern 32 read by the one-dimensional image sensor 24 should be ideally read is defined as p (read position in a state where no lateral displacement occurs), and the position correction pattern read this time is The difference lag between the position 32 and the position k is used for correcting the read image.
[0085]
For example, in the example of the image read by the one-dimensional image sensor 24 shown in FIG. 16A, a position to be ideally read (hereinafter, referred to as a reference position) is a1, and the position correction actually read is performed. When the position of the use pattern 32 is a2, it can be determined that the lateral rotation of the transparent rotating roller 29 has not occurred. On the other hand, when the reference position is b1 and the position correction pattern 32 is actually read at the position of b2, it may be determined that the transparent rotating roller 29 is shifted to the right. it can.
[0086]
FIG. 17 shows the correspondence between the fingerprint reading range in which the fingerprint pattern is read on the transparent rotating roller 29 and the one-dimensional image sensor 24. As shown in FIG. 17, it is assumed that the fingerprint reading range corresponds to M dots of the one-dimensional image sensor 24. In the lateral deviation correction processing, the lateral deviation is corrected by shifting the image of M dots read by the one-dimensional image sensor 24 to the right or left as shown in FIG. 18 according to the difference lag.
[0087]
The CPU 10 determines a difference between the position P and the position of the position correction pattern 32 that has been read this time based on the image data read by the one-dimensional image sensor 24 input through the A / D conversion circuit 28. Is calculated (step G1). Here, if the difference lag is “0”, no lateral displacement has occurred, and the lateral displacement correction processing ends (step G2, “0”).
[0088]
On the other hand, when the difference lag is minus (step G2, “−”), that is, when the transparent rotating roller 29 is shifted to the left, the position i of the corrected pixel is set to i = M−1 (step G3). ), Pixel value data at pixel position i _i Is the pixel value data at the pixel position of i-lag. _i-lag (Step G4). That is, the pixel value at the pixel position corresponding to the shift is shifted to the pixel value at the original pixel position.
[0089]
Next, i is updated as i = i−1 (step G5), and if i ≦ −lag (step G6, Yes), it is assumed that a pixel value to be further processed remains, and Similarly, the pixel value at each pixel position is shifted rightward by the difference lag (steps G4 to G5).
[0090]
When the shifting of each pixel position to be shifted is completed (No in step G6), data _i = 0 (step G7), and the pixel value is set to 0 while sequentially updating the value of i with i = i−1 for the remaining pixel positions up to 0 dot (steps G7, G8, G9).
[0091]
If the difference lag is positive (step G2, “+”), that is, if the transparent rotating roller 29 is shifted to the right, the corrected pixel position is set to i = 0 (step G10), and the pixel is corrected. Pixel value data of value i _i Is the pixel value data at the pixel position of i + lag. _{i + lag} (Step G11). That is, the pixel value at the pixel position corresponding to the shift is shifted to the pixel value at the original pixel position.
[0092]
Next, i is updated by setting i = i + 1 (step G12), and if i <M-lag (step G13, Yes), it is assumed that a pixel value to be further processed remains, and so on. Then, the pixel value at each pixel position is shifted leftward by the difference lag (steps G11 and G12).
[0093]
When the shift of each pixel position to be shifted is completed (No in step G13), data _i = 0, and the pixel value is set to 0 while sequentially updating the value of i with i = i + 1 for the remaining pixel positions up to N dots (steps G14, G15, G16).
[0094]
In this manner, the image data read by the one-dimensional image sensor 24 can be corrected by performing image processing for shifting the image data by the lateral displacement of the transparent rotating roller 29.
[0095]
In addition to the lateral displacement correction processing shown in the flowchart of FIG. 17, the position p serving as a correction index can be determined by first reading one or more times. For example, when the position of the vertical line (position correction pattern 32) read n times by the one-dimensional image sensor 24 is {ki | i = 0, 1,..., N−1}, the correction position p is It can be calculated by equation (7).
[0096]
(Equation 2)

[0097]
Note that, in the above description, a case has been described where lateral displacement correction is performed on image data read in the fingerprint reading range (M dots), but this corresponds to N image sensors of the one-dimensional image sensor 24. The lateral displacement can be similarly corrected for the image data of the rotation detection pattern (including the position correction pattern 32). Thereby, the accuracy of rotation detection with respect to the transparent rotating roller can be improved.
[0098]
Next, a specific example of the rotation detection pattern 30 applied to the transparent rotation roller 29 will be described.
19 to 21 show a cross-sectional shape of the axis of the transparent rotating roller 29 in a step shape in which the outer diameter changes stepwise, and the boundary of each step is a first straight line having a predetermined angle with respect to the axis. An example is shown in which a portion and a second linear portion parallel to the axis are formed so as to be alternately continuous (to form a saw-tooth shape) (rotation detection pattern 30 shown in FIG. 4). . FIG. 19 is a perspective view showing an external configuration of the transparent rotating roller 29, FIG. 20 is a view showing portions corresponding to the rotation detection pattern 30 and the position correction pattern 32 developed in a plane, and FIGS. (D) is a sectional view of the axis of the transparent rotating roller 29 (only one outer surface side is shown). First, a description will be given assuming that the cross section is formed as shown in FIG.
[0099]
As shown in FIG. 21A, A surface, B surface, C surface, and D surface having different outer diameters are formed on the outer peripheral surface of the transparent rotating roller 29. The A surface, B surface, C surface, and D surface are each processed into a so-called mirror surface having a smooth surface. In the cross-sectional shape shown in FIG. 21A, the same saw-tooth pattern is formed at each boundary (first boundary and second boundary) between the B surface and the C surface and between the C surface and the D surface. . In this pattern, the first boundary pattern and the second boundary pattern are formed such that portions parallel to the axes of the respective transparent rotating rollers 29 do not match. That is, the pattern is formed so as to be shifted so that the apex portion of the pattern does not coincide on the axis of the transparent rotating roller 29. The position correction pattern 32 is formed by the boundary between the A surface and the B surface.
[0100]
21 (a), the outer diameter of the transparent rotating roller 29 on the side A is 7.5 mm, and the thickness of the transparent rotating roller 29 on the side A is 0.5 mm. It is. As shown in FIG. 20, the distance between the vertices of the pattern formed by the boundary of each step is 18 ° in terms of the center angle of the roller diameter, and the distance between the vertices of the two patterns is 9 °. . Also, α = 0.111 mm (5 dots), β = 1.180 mm (28 dots), γ = 1.180 mm (28 dots), and δ = 0.422 mm (10 dots) shown in FIG. The shape of the transparent rotating roller 29 shown in FIGS. 19 to 21 is not limited to this numerical value.
[0101]
Also, in the cross-sectional shape shown in FIG. 21A, the boundary of each step is vertical (perpendicular to the axis of the roller). However, as shown in FIG. May exceed 90 °. In this case, when the image of the portion of the rotation detection pattern 30 and the position correction pattern 32 is read, the pattern portion (line) can be made thicker than the case where the boundary is formed vertically. Further, the step surface of the boundary may be formed on a diffusion surface (detected as white by the one-dimensional image sensor 24). The diffusion surface is a surface that is formed in a so-called grained surface with a rough surface, and that diffuses (irregular reflection) when light is applied.
[0102]
Further, in FIGS. 21 (a) and 21 (b), the outer diameter of the transparent rotating roller 29 on the end side is small, but as shown in FIGS. It is also possible to form such that the outside diameter of the side is large and the outside diameter of the A-side portion is the thinnest.
[0103]
Here, an outline of a method of manufacturing the transparent rotating roller 29 provided with the rotation detecting pattern 30 shown in FIGS. 19, 20 and 21A will be described with reference to FIGS. As shown in the cross-sectional views of FIGS. 22 and 23, a mold 40, a core 42, and an extrusion pin 44 are used for manufacturing the transparent rotating roller 29.
[0104]
First, the initial state of the cavity 40, the core 42, and the extrusion pin 44 when the transparent rotating roller 29 is manufactured is as shown in FIG. That is, by combining the cavity 40 and the core 42, a space is formed according to the shape of the transparent rotating roller 29, and a gate for injecting the material (for example, acrylic resin) of the transparent rotating roller 29 into this space. 46 and a runner 48 are secured.
[0105]
Here, as shown in FIG. 22 (2), the space formed by the cavity 40 and the core 42 is filled with, for example, an acrylic resin 49 through the gate 46 and the runner 48. Thereafter, as shown in FIG. 22 (3), when the resin 49 is cured, the mold 40 is opened. At this time, since the cross-sectional shape of the transparent rotating roller 29 has a stepped shape with the outer diameter smaller toward the tip, the mold 40 can be easily pulled out, and the rotation detecting pattern 30 can be formed with high accuracy.
[0106]
Next, as shown in FIG. 23 (4), the molded product in the core 42 is extruded by the extrusion pin 44, and the molded product is pulled out as shown in FIG. 23 (5). The molding of the transparent rotating roller 29 is completed by cutting the gate and liner portions.
[0107]
According to the manufacturing method described above, even when the transparent rotating roller 29 is mass-produced, the rotation detecting pattern 30 can be stably and accurately applied without significantly increasing the manufacturing cost. Therefore, by configuring the image reading device using the transparent rotating roller 29 that can be manufactured using this manufacturing method, stable image reading can be realized.
[0108]
Note that, in the example of the manufacturing method shown in FIGS. 22 and 23, the configuration shown in FIG. Are separated from each other at the boundary of. When the rotation detection pattern 30 has another shape, the rotation detection pattern 30 can be arbitrarily determined at a position where the separation between the mold 40 and the core 42 becomes easy according to the shape. For example, in the configuration having the cross sections shown in FIGS. 21C and 21D, the mold 40 and the core 42 may be separated at the boundary between the C plane and the D plane.
[0109]
When a diffusing surface is added to the transparent rotating roller 29, the surface shape of the cavity 40 or the core 42 corresponding to the diffusing surface portion is roughened (set as a diffusing surface) (FIG. 24, FIG. An example of the transparent rotating roller 29 shown in FIG. 27).
[0110]
Hereinafter, an example of the transparent rotating roller 29 provided with the rotation detecting pattern 30 having another shape will be described.
The rotation detection pattern 30 shown in FIGS. 24 to 26 shows an example in which a diffusion surface (texture surface) is provided on a tapered surface provided on the transparent rotation roller 29.
[0111]
FIG. 24 is a perspective view showing an external configuration of the transparent rotating roller 29, FIG. 25 is a diagram showing a portion corresponding to the rotation detecting pattern 30 and the position correcting pattern 32 developed in a plane, and FIG. FIG. 7 is a cross-sectional view of the shaft of the roller 29 (only one outer surface side is shown).
[0112]
As shown in FIG. 26, on the outer peripheral surface of the transparent rotating roller 29, in addition to the A surface having a constant outer diameter, a tapered surface having a smaller outer diameter at the front end portion is formed. The B surface, the C surface, and the D surface are formed on the tapered surface. The B and D surfaces are processed into mirror surfaces, and the C surface sandwiched between the B and D surfaces is processed into a diffusion surface. It is noted that the diffusion surface is added to a portion corresponding to the transparent rotation roller 29 by forming the diffusion surface on the cavity 40 or the core 42 in the method of manufacturing the transparent rotation roller 29 described above. , May be added by additional processing. In the cross-sectional shape shown in FIG. 26, the same saw-tooth pattern is formed at each boundary (first boundary and second boundary) between the B and C surfaces and the C and D surfaces. In this pattern, the first boundary pattern and the second boundary pattern are formed such that portions parallel to the axes of the respective transparent rotating rollers 29 do not match. That is, the pattern is formed so as to be shifted so that the apex portion of the pattern does not coincide on the axis of the transparent rotating roller 29. The position correction pattern 32 is formed by the boundary between the A surface and the B surface.
[0113]
As a specific numerical value, for example, as shown in FIG. 26, the outer diameter of the transparent rotating roller 29 on the side A is 7.5 mm, and the thickness of the transparent rotating roller 29 on the side A is 0.5 mm. As shown in FIG. 25, the distance (ε) between the vertices of the pattern formed by the boundary with the C plane (diffusion surface) is 18 °, and the distance (ζ) between the vertices of the two patterns is 9 °. It is. Further, α = 0.111 mm (5 dots), β = 1.180 mm (28 dots), γ = 1.180 mm (28 dots), and δ = 0.422 mm (10 dots) shown in FIG. The shape of the transparent rotating roller 29 shown in FIGS. 24 to 26 is not limited to this numerical value.
[0114]
The rotation detection pattern 30 shown in FIGS. 27 to 29 has a diffusion surface provided on the outer peripheral surface of the transparent rotation roller 29, and the boundary of the diffusion surface has a predetermined angle with respect to the axis of the transparent rotation roller 29. An example is shown in which one linear portion and a second linear portion parallel to the axis are formed alternately and continuously.
[0115]
FIG. 27 is a perspective view showing the external configuration of the transparent rotating roller 29, FIG. 28 is a diagram showing a portion corresponding to the rotation detecting pattern 30 and the position correcting pattern 32 developed in a plane, and FIG. FIG. 7 is a cross-sectional view of the shaft of the roller 29 (only one outer surface side is shown).
[0116]
As shown in FIG. 29, an A surface, a B surface, a C surface, and a D surface are formed on the outer peripheral surface of the transparent rotating roller 29. The A, B, and D surfaces are processed into mirror surfaces, and the C surface sandwiched between the B and D surfaces is processed into a diffusion surface. At the boundary between the A-side and the B-side, a position correcting pattern 32 is formed by a V-shaped groove having a V-shaped cross section. In the cross-sectional shape shown in FIG. 26, the same saw-tooth pattern is formed at each boundary (first boundary and second boundary) between the B and C surfaces and the C and D surfaces. In this pattern, the first boundary pattern and the second boundary pattern are formed such that portions parallel to the axes of the respective transparent rotating rollers 29 do not match. That is, the pattern is formed so as to be shifted so that the apex portion of the pattern does not coincide on the axis of the transparent rotating roller 29.
[0117]
As a specific numerical value, for example, as shown in FIG. 29, the outer diameter of each surface of the transparent rotating roller 29 is 7.5 mm, and the thickness of the transparent rotating roller 29 at each surface portion is 0.5 mm. Further, as shown in FIG. 28, the distance (ε) between the vertices of the pattern formed by the boundary with the C plane (diffusion surface) is 18 °, and the distance (ζ) between the vertices of the two patterns is 9 °. It is. Further, α = 0.111 mm (5 dots), β = 1.180 mm (28 dots), γ = 1.180 mm (28 dots), and δ = 0.422 mm (10 dots) shown in FIG. The shape of the transparent rotating roller 29 shown in FIGS. 27 to 29 is not limited to this numerical value.
[0118]
The rotation detection pattern 30 shown in FIGS. 30 to 32 has a plurality of line portions having a predetermined length (for example, a predetermined length) parallel to the axis of the transparent rotation roller 29 formed at equal intervals. An example is shown.
[0119]
FIG. 30 is a perspective view showing the external configuration of the transparent rotating roller 29, and FIG. 31 is a view showing portions corresponding to the rotation detection pattern 30 and the position correction pattern 32 developed in a plane, and FIGS. (B2) is a cross-sectional view of the axis of the transparent rotating roller 29 (only one outer surface side is shown).
[0120]
As shown in FIGS. 30 and 31, on the outer peripheral surface of the transparent rotating roller 29, A surface and B surface having different outer diameters are formed, and for example, the surface is processed into a smooth mirror surface. On the surface B, a plurality of V-shaped grooves having a predetermined length parallel to the axis of the transparent rotating roller 29 are formed at equal intervals. The V-groove is formed from an end of the transparent rotating roller 29. Further, a position correction pattern 32 is formed by a step between the surface A and the surface B.
[0121]
FIG. 32 (a1) is a cross-sectional view of the portion indicated by X in FIG. 30 as viewed from the axial direction of the transparent rotating roller 29. As shown in FIG. 32 (a1), each V-groove is formed such that the groove width of the V-groove is equal to the width of the B surface sandwiched between the V-grooves. The interval (pitch) at which the V-groove is formed is formed according to the timing (resolution) at which an image is taken in with the rotation of the transparent rotating roller 29. For example, when the V-groove portion is detected as a bright portion (that is, white) by the one-dimensional image sensor 24 and the B-side portion is detected as a dark portion (that is, black), the rotation detection pattern is set according to the read timing. The rotation detection image obtained by reading the portion 30 is formed so as to be switched to white, black, white, and so on.
[0122]
FIG. 32 (a2) shows a cross section taken along the line X1 in FIG. 32 (a1). In the example shown in FIG. 32 (a2), the outer diameter of the surface A is formed larger.
[0123]
As a specific numerical value, for example, as shown in FIG. 32, the outer diameter of the transparent rotating roller 29 on the A side is 7.5 mm, and the thickness of the transparent rotating roller 29 on the A side portion is 0.5 mm. As shown in FIG. 31, as the reference position for reading the line portion by the one-dimensional image sensor 24, α = 0.842 mm (20 dots), β = 0.422 mm (10 dots), and γ = 0.634. ° (center angle of roller diameter). The shape of the transparent rotating roller 29 shown in FIGS. 30 to 32 (a1) and (a2) is not limited to this numerical value.
[0124]
The line portions (V-groove, V-convex) shown in FIGS. 30 and 31 are formed on the transparent rotating roller 29 so that white and black are detected at equal intervals. The gap may be formed wider (for example, γ = 1.286 °). In this case, when reading by the one-dimensional image sensor 24 between the line portions, the portion of the surface B is continuously read, but the portion of the position correction pattern 32 is also read at the same time. That is, no matter what timing an image is read, white and black portions exist in the read image data. Therefore, the above-described correction data generation processing (FIG. 7) and the correction data appropriateness determination processing can be executed without any trouble.
[0125]
In FIGS. 32 (a1) and (a2), the line portions are formed by V-grooves. As shown in FIGS. 32 (b1) and 32 (b2), the line portion can be formed by a V-convex (V-shaped convex shape). FIG. 32 (b1) is a cross-sectional view of the portion indicated by X in FIG. 30 as viewed from the axial direction of the transparent rotating roller 29. As shown in FIG. 32 (b1), each V-convex is formed such that the width of the V-convex and the width of the B surface sandwiched between the V-convex are at equal intervals. A cross section taken along line X2 in FIG. 32 (b1) is shown in FIG. 32 (b2). In the example shown in FIG. 32 (b2), the outer diameter of the surface B is formed larger.
[0126]
Thus, even if the line portion is formed by the V-shaped protrusion, it can be used in the same manner as the case where the line portion is formed by the V-shaped groove. In the case of manufacturing the transparent rotating roller 29 having the configuration shown in FIGS. 32 (b1) and (b2), the position at which the mold 40 and the core 42 are separated from each other is, for example, set at the boundary between the A-side and the B-side. Good manufacturing is possible.
[0127]
The rotation detecting pattern 30 shown in FIGS. 33 to 35 has a line portion having a predetermined length parallel to the axis of the transparent rotating roller 29 in the same manner as the rotation detecting pattern 30 shown in FIGS. An example is shown in which a plurality of lines are formed at intervals, and an envelope formed by one end of a predetermined number of line portions further forms a straight line having a predetermined angle with respect to the axis of the transparent rotating roller 29. ing.
[0128]
FIG. 33 is a perspective view showing an external configuration of the transparent rotating roller 29, FIG. 34 is a view showing portions corresponding to the rotation detection pattern 30 and the position correction pattern 32 developed in a plane, and FIGS. (B2) is a cross-sectional view of the axis of the transparent rotating roller 29 (only one outer surface side is shown). The rotation detection patterns 30 shown in FIGS. 33 to 35 are configured in the same manner as those shown in FIGS.
[0129]
As shown in FIGS. 33 to 34, the line portions forming the rotation detection pattern 30 have a line length that becomes shorter in order for each predetermined number, and the envelope (a line in contact with the tip of the line portion) forms a straight line. are doing. Accordingly, the entire envelope of the rotation detecting pattern 30 formed on the transparent rotating roller 29 is formed like a saw tooth (see FIG. 34).
[0130]
Specifically, as shown in FIG. 35, for example, as shown in FIG. 35, the outer diameter of the transparent rotating roller 29 on the A side is 7.5 mm, and the thickness of the transparent rotating roller 29 on the A side portion is 0.5 mm. Further, as shown in FIG. 34, as the reference position for reading the line portion by the one-dimensional image sensor 24, α = 0.111 mm (5 dots), β = 0.842 mm (20 dots), and γ = 0.111 mm ( 5), and δ = 0.643 °. The shape of the transparent rotating roller 29 shown in FIGS. 33 to 35 is not limited to this numerical value.
[0131]
As described above, since the interval (pitch) at which the line portion is formed is determined in accordance with the reading resolution, the rotation can be stably detected at the end point of the saw tooth based on the rotation detection image. . Further, since the envelope of the line portion forms a saw tooth, the rotation direction of the transparent rotating roller 29 is detected from a change in the length of the portion corresponding to the line portion read by the one-dimensional image sensor 24. You can also.
[0132]
In the above description, the case where the image data reading device according to the present embodiment is mounted on a mobile phone is described as an example. However, the image data reading device may be mounted on another information device, or the image data reading device may be mounted on another information device. May be configured alone. When configured alone as an image data reading device, it is used by connecting to various information devices such as a personal computer and a communication device. The image reading device may record an image read by the one-dimensional image sensor 24 at a timing corresponding to a change in the rotation detection pattern 30 and output the image in response to a request from an information device. The image read by the image sensor 24 may be sequentially output to the information device, and the information device may record a necessary image (representing a fingerprint pattern) at a timing corresponding to a change in the rotation detection pattern 30. .
[0133]
Further, in the above description, the case where a fingerprint pattern, which is image data of a fingertip, is read is described. However, when the image data is read by bringing a pattern of another human body part such as a palm print pattern into contact with the detection part, The effect can be obtained by applying when is a soft material.
[0134]
Further, the present invention is not limited to the above-described embodiment, and can be variously modified in an implementation stage without departing from the gist thereof. In addition, the contents of the above-described embodiments may be implemented in appropriate combinations as much as possible. The embodiments described above include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent features. For example, even if some components are deleted from all the components shown in the embodiment, if the effect is obtained, a configuration from which the components are deleted can be extracted as an invention.
[0135]
【The invention's effect】
As described above, according to the present invention, it is possible to realize stable reading of an image using a rotation detecting pattern attached to a roller with high accuracy without increasing manufacturing cost. .
[0136]
Further, it is possible to realize stable reading of an image without being affected by the deviation of the roller in the left-right direction at the time of reading the image using the roller and the variation in manufacturing accuracy of the roller.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an electronic circuit of a mobile phone equipped with an image reading device according to a first embodiment of the present invention.
FIG. 2 is an exemplary external view of a mobile phone on which a fingerprint reading unit 20 according to the embodiment is mounted.
FIG. 3 is a diagram showing a schematic configuration (side sectional view) of a mechanical portion of the fingerprint reading unit 20 according to the first embodiment.
FIG. 4 is a perspective view showing the appearance of a transparent rotating roller 29 provided with a rotation detecting pattern 30;
FIG. 5 is a diagram showing a correspondence relationship between a rotation detecting pattern 30 provided on a transparent rotating roller 29 and an image sensor of the one-dimensional image sensor 24.
FIG. 6 is a view showing a flowchart of a timing determination process in the first embodiment.
FIG. 7 is a flowchart for explaining correction data generation processing in the timing determination processing.
FIG. 8 is a flowchart illustrating a rotation detection image extraction process in the timing determination process.
FIG. 9 is a flowchart illustrating an image capture timing determination process in the timing determination process.
FIG. 10 is a diagram showing a rotation detection pattern 30 applied to a transparent rotation roller 29, which is developed in a plane for easy understanding.
FIG. 11 is a diagram for explaining a change in the position of a pattern portion in a rotation detection image.
FIG. 12 is a view for explaining movement of a pattern portion in a rotation detection image.
FIG. 13 is a flowchart illustrating a timing determination process according to the second embodiment.
FIG. 14 is a flowchart of correction data appropriateness determination processing.
FIG. 15 is a flowchart illustrating a lateral shift correction process.
FIG. 16 is a view for explaining a lateral displacement of the transparent rotating roller 29.
FIG. 17 is a diagram showing a correspondence relationship between a fingerprint reading range in which a fingerprint pattern is read on a transparent rotating roller 29 and the one-dimensional image sensor 24;
FIG. 18 is a diagram illustrating a situation in which image data is shifted right or left by lateral displacement correction processing.
FIG. 19 is a perspective view showing an external configuration of a transparent rotating roller 29.
FIG. 20 is a diagram showing a part corresponding to a rotation detection pattern 30 and a position correction pattern 32 developed in a plane.
FIG. 21 is a cross-sectional view along the axis of the transparent rotating roller 29.
FIG. 22 is a diagram for explaining a method of manufacturing the transparent rotating roller 29 provided with the rotation detecting pattern 30.
FIG. 23 is a view for explaining a method of manufacturing the transparent rotating roller 29 provided with the rotation detecting pattern 30.
FIG. 24 is a perspective view showing an external configuration of a transparent rotating roller 29.
FIG. 25 is a diagram showing a portion corresponding to a rotation detection pattern 30 and a position correction pattern 32 developed in a plane.
FIG. 26 is a cross-sectional view along the axis of the transparent rotating roller 29.
FIG. 27 is a perspective view showing an external configuration of a transparent rotating roller 29.
FIG. 28 is a diagram in which portions corresponding to the rotation detection pattern 30 and the position correction pattern 32 are developed in a plane.
FIG. 29 is a cross-sectional view of the axis of the transparent rotating roller 29.
FIG. 30 is a perspective view showing an external configuration of a transparent rotating roller 29.
FIG. 31 is a diagram showing a part corresponding to a rotation detection pattern 30 and a position correction pattern 32 developed in a plane.
FIG. 32 is a cross-sectional view along the axis of the transparent rotating roller 29.
FIG. 33 is a perspective view showing an external configuration of a transparent rotating roller 29.
FIG. 34 is a diagram showing a portion corresponding to a rotation detection pattern 30 and a position correction pattern 32 developed in a plane.
FIG. 35 is a cross-sectional view along the axis of the transparent rotating roller 29.
[Explanation of symbols]
10 CPU
12 ... Storage device
14 ... RAM
16… Call unit
18 Display unit
19 ... Key part
20: Fingerprint reader
21 ... Light source
22 ... Selfoc lens (lens optical system)
24 ... one-dimensional image sensor
26 ... Imaging control circuit
27 ... A / D conversion circuit
28 ... Rotation detection sensor
29 ... Transparent rotating roller
30 ... Rotation detection pattern
32 ... Position correction pattern
40 ... Cabi
42 ... core
44 ... Extrusion pin

Claims (16)

In an image reading device that reads an image of the surface of the subject, a transparent rotating roller provided with a pattern formed by providing a plurality of steps on the outer peripheral surface over one circumference,
An imaging unit that reads an image of the subject that has come into contact with the transparent rotating roller together with the pattern attached to the transparent rotating roller,
An image reading apparatus, comprising: an image recording unit that records an image of the subject at a timing corresponding to a change in a rotation detection image corresponding to the pattern read by the imaging unit. The pattern has a stepped shape in which the cross-sectional shape in the axis of the transparent rotating roller changes stepwise in outer diameter, and the boundary of each step is a first linear portion having a predetermined angle with respect to the axis. 2. The image reading apparatus according to claim 1, wherein the second linear portion parallel to the axis is formed so as to be alternately continuous. The pattern is provided with at least a first boundary and a second boundary, and the shape of the first boundary and the shape of the second boundary are such that the respective second linear portions are on the axis. 3. The image reading device according to claim 2, wherein the image reading device is formed so as not to match. In an image reading device that reads an image of the surface of the subject,
A transparent rotating roller provided with a pattern formed by providing a diffusion surface for diffusing light on the outer peripheral surface over one circumference;
An imaging unit that reads an image of the subject that has come into contact with the transparent rotating roller together with the pattern attached to the transparent rotating roller,
An image reading apparatus, comprising: an image recording unit that records an image of the subject at a timing corresponding to a change in a rotation detection image corresponding to the pattern read by the imaging unit. The transparent rotating roller is provided with a tapered surface,
The image reading apparatus according to claim 4, wherein the pattern is formed by providing a diffusion surface on the tapered surface. The boundary of the diffusion surface is formed such that a first linear portion having a predetermined angle with respect to the axis and a second linear portion parallel to the axis are alternately continuous. The image reading device according to claim 4, wherein In an image reading device that reads an image of the surface of the subject,
A transparent rotating roller in which a pattern in which a plurality of line portions having a predetermined length parallel to the axis are formed at equal intervals over one circumference of the outer peripheral surface;
An imaging unit that reads an image of the subject that has come into contact with the transparent rotating roller together with the pattern attached to the transparent rotating roller,
An image reading apparatus, comprising: an image recording unit that records an image of the subject at a timing corresponding to a change in a rotation detection image corresponding to the pattern read by the imaging unit. 8. The image reading apparatus according to claim 7, wherein a line portion attached to the transparent rotating roller is formed in a concave shape. 8. The image reading apparatus according to claim 7, wherein a line portion attached to the transparent rotating roller is formed in a convex shape. The image according to claim 7, wherein an envelope formed by one end of the line portion for each predetermined number forms a straight line having a predetermined angle with respect to the axis of the transparent rotating roller. Reader. In an image reading device that reads an image of the surface of the subject,
A transparent rotating roller in which an outer peripheral line pattern perpendicular to the axis is attached to the outer peripheral surface over one round,
An imaging unit that reads an image of the subject that has come into contact with the transparent rotating roller together with the pattern attached to the transparent rotating roller,
An image reading apparatus, comprising: an image recording unit that records an image of the subject at a timing corresponding to a change in a rotation detection image corresponding to the pattern read by the imaging unit. The image reading apparatus according to claim 11, wherein the outer peripheral line pattern is formed by a step boundary in which an outer diameter of a cross-sectional shape of the axis of the transparent rotating roller changes stepwise. The image reading apparatus according to claim 11, wherein the outer peripheral line pattern is formed by a groove provided on an outer peripheral surface of the transparent rotating roller. Based on a position correction image corresponding to a portion of the outer peripheral line pattern read by the imaging unit, the image processing apparatus further includes a position correction unit that corrects an image position of the subject read by the imaging unit.
The image reading apparatus according to claim 11, wherein the image recording unit records the image of the subject whose position has been corrected by the position correction unit. Setting means for setting a reference value for correction for each of the plurality of image sensors constituting the imaging means, based on an image corresponding to the pattern read by the imaging means;
The image reading apparatus according to claim 11, further comprising: a correction unit configured to correct the rotation detection image based on a reference value set by the setting unit. The setting means,
For each of the plurality of imaging elements of the imaging means, with the rotation of the transparent rotating roller, setting the average value of the maximum value and the minimum value of the pixel values read by the imaging element so far as a reference value. The image reading device according to claim 15, wherein

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