JPH02188888A - Fingerprint image input device - Google Patents
Fingerprint image input deviceInfo
- Publication number
- JPH02188888A JPH02188888A JP1008117A JP811789A JPH02188888A JP H02188888 A JPH02188888 A JP H02188888A JP 1008117 A JP1008117 A JP 1008117A JP 811789 A JP811789 A JP 811789A JP H02188888 A JPH02188888 A JP H02188888A
- Authority
- JP
- Japan
- Prior art keywords
- fingerprint
- image
- transparent substrate
- input device
- finger
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000000758 substrate Substances 0.000 claims abstract description 28
- 238000001514 detection method Methods 0.000 claims description 5
- 239000012530 fluid Substances 0.000 abstract description 5
- 210000004243 sweat Anatomy 0.000 abstract description 5
- 239000011295 pitch Substances 0.000 abstract 2
- 239000004519 grease Substances 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 8
- 230000003287 optical effect Effects 0.000 description 6
- 238000003384 imaging method Methods 0.000 description 3
- 238000012795 verification Methods 0.000 description 3
- 230000002159 abnormal effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 208000008454 Hyperhidrosis Diseases 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 230000001678 irradiating effect Effects 0.000 description 1
- 238000000206 photolithography Methods 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
- 208000013460 sweaty Diseases 0.000 description 1
Classifications
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- G06V40/00—Recognition of biometric, human-related or animal-related patterns in image or video data
- G06V40/10—Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
- G06V40/12—Fingerprints or palmprints
- G06V40/13—Sensors therefor
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は指紋照合システムに係り、特に指紋押捺時のパ
ターン切れ等指紋像欠落部の発生を防止して指紋照合率
の向上を図った指紋像入力装置に関する。[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fingerprint verification system, and in particular, to a fingerprint verification system that improves the fingerprint verification rate by preventing the occurrence of missing parts of the fingerprint image such as pattern breakage when fingerprints are stamped. The present invention relates to an image input device.
３、発明の詳細な説明
〔概 要〕
指紋照合システムの指紋像人力装置に関し、指紋照合率
の向上を図ることを目的とし、〔従来の技術〕
個人の識別法として指紋の照合を行うシステムが用いら
れている。3. Detailed Description of the Invention [Summary] The purpose of this invention is to improve the fingerprint matching rate with respect to a fingerprint image manual device for a fingerprint matching system. It is used.
このシステムでは指紋を画像として取り扱うのが普通で
あり、そのため指紋を画像データに変換する入力装置が
必要となる。This system typically treats fingerprints as images, and therefore requires an input device that converts fingerprints into image data.
第２図は従来の入力装置主要部を例示する原理図であり
、（八）は構成図をまた（Ｂ）は問題点を説明する図で
ある。FIG. 2 is a principle diagram illustrating the main parts of a conventional input device, (8) is a configuration diagram, and (B) is a diagram illustrating problems.
断面を示す第２図（Ａ）で、１はガラスやプラスチック
等よりなる透明基板であり、その表面所定位置には例え
ば２０ Ｘ ２０ｍｍ程度の大きさの指紋押捺部１ａを
備えると共に、該透明基板には該指紋押捺部１ａで押捺
した指紋の画像信号を該透明基板１から１１出さ−Ｕる
所定の端面１ｂ部分が所定角度αの斜面として形成され
ている。In FIG. 2 (A) showing a cross section, 1 is a transparent substrate made of glass, plastic, etc., and a fingerprint imprinting part 1a of, for example, 20 x 20 mm is provided at a predetermined position on the surface of the substrate. A predetermined end surface 1b portion from which an image signal of the fingerprint stamped by the fingerprint stamping section 1a is outputted from the transparent substrate 1 is formed as a slope with a predetermined angle α.
また２は上記指紋押捺部１ａと対応して該透明基板ｌの
他面側の所定位置に配置した光源、３は上記端面１ｂか
ら射出する指紋の画像信号をイメージセンサ４に結像さ
せる結像光学系をそれぞれ示している。Further, 2 is a light source arranged at a predetermined position on the other side of the transparent substrate l corresponding to the fingerprint imprinting portion 1a, and 3 is an imager for forming an image of the fingerprint image signal emitted from the end surface 1b on the image sensor 4. Each optical system is shown.
かかる構成になる入力装置主要部での画像信号の光路を
以下図によって説明する。The optical path of the image signal in the main part of the input device having such a configuration will be explained below with reference to the drawings.
指５の指紋側を上記透明基板１の指紋押捺部１ａに押捺
すると、指紋凸部の指紋隆線５ａは該透明基板１の表面
に線状となって接触するが指紋凹部の指紋谷線５ｂは接
触しない。When the fingerprint side of the finger 5 is pressed on the fingerprint imprinting portion 1a of the transparent substrate 1, the fingerprint ridges 5a of the fingerprint convex portion contact the surface of the transparent substrate 1 in a line shape, but the fingerprint trough lines 5b of the fingerprint concave portion contact. do not touch.
そこで上記の光源２から射出する光線りを指紋押捺部１
ａと反対側の面１ｃから該透明基板１を通して上記の指
紋押捺部１ａに投射すると、透明基板１の表面と接触し
ない指紋谷線５ｂに相当する部分に到達する光線は該指
紋押捺部１ａの面から一旦空気中に射出し指紋谷線５ｂ
の表面で反射して該透明基板１に再入射するＬｌｏとな
るが、スネルの法則によって入射面１ｃがら空気層に出
射する。Therefore, the light beam emitted from the light source 2 is applied to the fingerprint stamping section 1.
When the light rays are projected from the surface 1c opposite to the surface 1c through the transparent substrate 1 onto the fingerprint stamping section 1a, the light beams that reach the portions corresponding to the fingerprint valley lines 5b that do not come into contact with the surface of the transparent substrate 1 are reflected from the fingerprint stamping section 1a. Once injected into the air from the surface, the fingerprint valley line 5b
The light Llo is reflected by the surface of the transparent substrate 1 and re-enters the transparent substrate 1, but according to Snell's law, it is emitted from the incident surface 1c into the air layer.
一方、該透明基板１の表面と接触している指紋隆線５ａ
部分に到達する光線は該当接界面で散乱光となって該透
明基板１内に反射する。On the other hand, fingerprint ridges 5a in contact with the surface of the transparent substrate 1
The light beam reaching the part becomes scattered light at the corresponding interface and is reflected into the transparent substrate 1.
この反射光の一部は入射面１ｃがら空気層に出射される
が、臨界角度より大きい角度で上記入射面ｌｃに進む光
Ｌ１は球面波となって該透明基板１内で全反射を繰り返
しながら該透明基板１内を伝播した後、端面１ｂから信
号光Ｌ２となって外部に導出される。A part of this reflected light is emitted from the incident surface 1c to the air layer, but the light L1 that advances to the incident surface lc at an angle larger than the critical angle becomes a spherical wave and is repeatedly totally reflected within the transparent substrate 1. After propagating within the transparent substrate 1, the signal light L2 is output from the end face 1b to the outside.
この信号光Ｌ２を結像光学系３でイメージセンサ４に結
像することによって上記指５の指紋像が入手できる。By focusing this signal light L2 on the image sensor 4 using the imaging optical system 3, a fingerprint image of the finger 5 can be obtained.
問題点を説明する図（Ｂ）は図（八）の指紋隆線５ａ部
における断面を図示悼方向から見たもので、■は正常な
場合をまた■は非正常な場合をそれぞれ示している。な
お図の矢印り方向は上記透明基板１上を押捺している指
５の指紋隆線５ａの長手方向を表わしている。Diagram (B) for explaining the problem is a cross section of the fingerprint ridge 5a in diagram (8) viewed from the direction of illustration, where ■ indicates a normal case, and ■ indicates an abnormal case. . Note that the direction of the arrow in the figure represents the longitudinal direction of the fingerprint ridge 5a of the finger 5 pressing on the transparent substrate 1.
かかる構成になる従来の指紋像入力装置では指紋押捺部
１ａの面は平坦面である。In the conventional fingerprint image input device having such a configuration, the surface of the fingerprint stamping portion 1a is a flat surface.
この場合、指５の指紋隆線５ａと該指紋押捺部１８面と
の接触が確実になされていれば図■に示すように該隆線
５ａはその全長にわたって該指紋押捺部１８面と接触す
るごとになるため図■１に示すように完全な指紋Ｓを検
出することができる。In this case, if the fingerprint ridge 5a of the finger 5 and the surface of the fingerprint-stamped part 18 are securely contacted, the ridge 5a will come into contact with the surface of the fingerprint-stamped part 18 over its entire length, as shown in FIG. Therefore, a complete fingerprint S can be detected as shown in Figure 1.
しかし、通常５００ｇ程度またはそれ以上を必要とする
指５の押圧が少ない場合や指紋表面に汗。However, if there is little pressure from the finger 5, which normally requires about 500g or more, or if the fingerprint surface is sweaty.
脂肪等の流体層が介在する場合には、指紋隆線５ａば全
長にわたって該指紋押捺部１８面と接触せず図■に示す
如き単離部５ａ’＋５ａ”を生ずる。When a fluid layer such as fat is present, the fingerprint ridge 5a does not come into contact with the surface of the fingerprint stamping portion 18 over its entire length, resulting in an isolated portion 5a'+5a'' as shown in FIG.
特にこの単離部５ａ″ ５ａ１１は空気層もしくは汗。In particular, this isolated part 5a'' 5a11 is an air layer or sweat.
脂肪等の流体層であるため図（Ａ）における指紋谷線５
ｂ部分と同様に到達する光線をイメージセンサ４の方に
導出することがない。Fingerprint valley line 5 in figure (A) because it is a fluid layer such as fat.
Similarly to part b, the arriving light rays are not guided toward the image sensor 4.
従って、図■°に示すように指紋パターンに切断や欠落
部分を発生させるため指紋像に不明瞭な領域が増大し、
指紋照合システムとしての照合率を低下させることにな
る。Therefore, as shown in Figure ■°, cuts and missing parts occur in the fingerprint pattern, increasing unclear areas in the fingerprint image.
This will reduce the matching rate of the fingerprint matching system.
（発明が解決しようとする課題）
従来の構成になる指紋像入力装置では、指の押捺力が少
ない場合や指紋表面に汗、脂肪等の如き流体層が介在す
ると、指紋隆線が連続したパターンとならず指紋照合シ
ステムの照合率を低下させると言う問題があった。(Problems to be Solved by the Invention) In the conventional fingerprint image input device, when the pressing force of the finger is small or when there is a fluid layer such as sweat or fat on the fingerprint surface, the fingerprint image input device has a continuous pattern of fingerprint ridges. However, there was a problem in that it lowered the matching rate of the fingerprint matching system.
上記問題点は、透明基板の所定位置に設けた指紋押捺部
に被検体を当接せしめた状態で該透明基板の裏面側所定
位置から該透明基板を通して上記被検体を光照射し、該
被検体から反射する画像光を画像検出部で指紋画像とし
て検出する指紋照合システＪ、のＩ旨紋像入力装置にお
いて、透明基板の上記指紋押捺部会面が、所定高さを有
する凸部を少なくとも上記画像検出部の解像分解能より
細かいピンチで配置した凹凸面で形成されてなる指紋像
入力装置によって解決される。The above problem can be solved by irradiating the subject with light from a predetermined position on the back side of the transparent substrate through the transparent substrate while the subject is in contact with a fingerprint imprinting part provided at a predetermined position on the transparent substrate. In a fingerprint image input device of a fingerprint matching system J, in which image light reflected from a transparent substrate is detected as a fingerprint image by an image detection unit, the fingerprint imprinting portion face of the transparent substrate has a convex portion having a predetermined height at least above the image. This problem can be solved by a fingerprint image input device formed of an uneven surface arranged with a finer resolution than the resolution of the detection section.
〔作 用）
−・般に微小な凸部を微細ピッチで指紋押捺面の全面に
付与すると、該指紋押捺面を押捺する被検体すなわち指
の押圧か弱くても被検体すなわち指が上記凸部の先端部
と接触し易くなると共に、該凸部が指紋表面特に隆線部
分の汗や脂肪等の流体層を突き破ることから隆線パター
ンの切断や欠落部分を連結させることが可能となり、指
紋パターンの不明瞭部分をなくすことができる。[Function] - In general, when minute convex portions are applied to the entire surface of the fingerprint imprinting surface at a fine pitch, even if the pressure of the subject, i.e., the finger pressing the fingerprint imprinting surface is weak, the subject, i.e., the finger presses the fingerprint imprinting surface. In addition to making it easier to contact the tip, the convex part breaks through the fluid layer of sweat, fat, etc. on the fingerprint surface, especially in the ridge area, making it possible to connect the cut or missing parts of the ridge pattern, thereby improving the fingerprint pattern. It is possible to eliminate ambiguous parts.
一方、イメージセンナの解像分解能より小さい画像信号
は該イメージセンサは感知しない。On the other hand, the image sensor does not sense an image signal smaller than the resolution of the image sensor.
本発明では、指紋像入力装置を構成する透明基板の指紋
押捺面の全面に、高さが指紋隆線の谷線からの高さより
低い凸部を画像検出部すなわちイメージセンサの解像分
解能より細かいピッチ間隔に配置した凹凸を形成してい
る。In the present invention, a convex portion having a height lower than the height from the valley line of the fingerprint ridge is formed on the entire surface of the fingerprint imprinting surface of the transparent substrate constituting the fingerprint image input device, which is finer than the resolution of the image detection unit, that is, the image sensor. It forms unevenness arranged at pitch intervals.
従って、従来パターン切れや欠落で発生していたパター
ン不明瞭部分が連結できることから指紋照合率の高い指
紋像入力装置を実現さ・口ることができる。Therefore, unclear portions of the pattern, which conventionally occur due to pattern breaks or omissions, can be connected, making it possible to realize a fingerprint image input device with a high fingerprint matching rate.
第１図は本発明になる指紋像入力装置を説明する図であ
る。FIG. 1 is a diagram illustrating a fingerprint image input device according to the present invention.
第１図で（１）は主要部を示す拡大図１（２）は指紋押
捺状態を示す図、（３）は指紋像の一例を示す図である
。In FIG. 1, (1) is an enlarged view of the main part, (2) is a view showing a fingerprint imprinted state, and (3) is a view showing an example of a fingerprint image.
第１図に示す本発明になる指紋像入力装置が第２図に示
す指紋像入力装置と異なる点は、第１図（１）に示す如
く透明基板１０の指紋押捺部１０ａに、例えば通常のフ
ォト・リソグラフィ技術を用いて高ざ１０〜２０μｍの
四角雄状の突起ｌＯｂをピンチ２０μｍ程度の間隔で全
面配置したことにある。The fingerprint image input device according to the present invention shown in FIG. 1 is different from the fingerprint image input device shown in FIG. 2 in that, as shown in FIG. The reason is that square male-shaped protrusions lOb having a height of 10 to 20 .mu.m are arranged on the entire surface at intervals of about 20 .mu.m by using photolithography technology.
通常一般の指紋センソでは、入力面に換算した画像信号
の解像分解能は５０μｍ程度である。従って該透明基板
１０の表面に１−記の如き寸法のモザイク状凹凸を形成
しても該凹凸の画像を該センサが感知することがない。Normally, in a general fingerprint sensor, the resolution of the image signal converted to the input surface is about 50 μm. Therefore, even if a mosaic-like unevenness having dimensions as shown in 1- is formed on the surface of the transparent substrate 10, the image of the unevenness will not be detected by the sensor.
−・方、通常の指紋では谷線部分を基準としたときの隆
線の高さは約１００μｍ程度である。従って高さが１０
〜２０〃ｍの凹凸形成面に指を押捺しても該凹凸面によ
って指紋の谷線部分まで影響を及ぼすことがない。- On the other hand, in a normal fingerprint, the height of the ridge line is about 100 μm when the valley line portion is used as a reference. Therefore the height is 10
Even if a finger is pressed against the uneven surface of ~20 m, the uneven surface does not affect the valley line portion of the fingerprint.
このことから上記のようなモザイク状凹凸が形成された
指紋押捺部１０ａに指を押捺した状態で光源２から射出
する光線りを該指紋押捺部１０ａに照射しても、結像光
学系３を通りイメージセンサ４で検知される画像は指紋
押捺部１０ａの凹凸に左右されることがなく指紋の隆線
部分のパターン情報のみを入手することができる。Therefore, even if the light beam emitted from the light source 2 is applied to the fingerprint stamped part 10a with a finger pressed against the fingerprint stamped part 10a on which the mosaic-like unevenness is formed, the imaging optical system 3 The image detected by the image sensor 4 is not affected by the unevenness of the fingerprint stamping part 10a, and only the pattern information of the ridge portion of the fingerprint can be obtained.
指紋押捺状態を示す図（２）で、矢印りは第２図（Ｂ）
同様に指紋隆線５ａの長手方向を示している。Figure (2) shows the state of fingerprint imprinting, and the arrow indicates Figure 2 (B).
Similarly, the longitudinal direction of the fingerprint ridge 5a is shown.
図で、例えば突起１０ｂのピークｐｌ−ｐｍの間および
ｐ、〜ｐ１゜は該指紋隆線５ａがこれらの各ピークと完
全に馴染んだ状態にあることを示し、イメージセンサ４
が検知する指紋画像は第２図（Ｂ）■“の如き正常画像
となる領域である。In the figure, for example, between the peaks pl and pm of the protrusion 10b and between p and ~p1°, the fingerprint ridge 5a is completely blended with each of these peaks, and the image sensor 4
The fingerprint image detected by the scanner is a normal image area as shown in FIG. 2(B).
またピークｐ、〜ｐ８の間は、指の押圧か弱いかまたは
汗または脂肪等が介在して第２図（Ｂ）■゛の如くに指
紋隆ｖＡＳａに切断や欠落等を生ずる非正常な領域に相
当するが、図では各ピークｐ、〜ｐＩｌがその先端部分
で該隆線５ａと接した状態にあることを示している。In addition, between peaks p and p8, there is an abnormal area where the fingerprint ridge vASa is cut or missing due to weak finger pressure or sweat or fat, etc., as shown in Figure 2 (B). Correspondingly, the figure shows that each of the peaks p, ~pIl is in contact with the ridge 5a at its tip.
この場合のイメージセンサ４で検知した結果の一例を（
３）に示しているが、図では例えばｐ、以前の正常パタ
ーンとｐ、以降の正常パターンおよびｐ５１）６１ ＋
’、＋ Ｉ）ｅの各接触点を結ぶ線とで該指紋Ｓが検知
されている。An example of the results detected by the image sensor 4 in this case is (
3), in the figure, for example, p, the previous normal pattern and p, the subsequent normal pattern and p51) 61 +
', + I) The fingerprint S is detected between the lines connecting the contact points of e.
すなわち従来切断または欠落して不明瞭であった部分が
図の如く連結された状態でイメージセンサ４に検知され
ることになる。In other words, the parts that were unclear due to cutting or missing in the past are detected by the image sensor 4 in a connected state as shown in the figure.
従って指紋像としての不明瞭領域がなくなることからシ
ステムとしての指紋像照合率を向上させることができる
。Therefore, since there is no ambiguous area as a fingerprint image, it is possible to improve the fingerprint image matching rate as a system.
Ｊ、述の如く本発明により、指紋■、ｑ合システムとし
ての指紋照合率が向上する指紋像入力装置を提供するこ
とができる。J. As described above, according to the present invention, it is possible to provide a fingerprint image input device that improves the fingerprint matching rate as a fingerprint matching system.
なお本発明の説明に当たっては、指紋押捺部の微細な突
起を四角錐状に形成した場合について行っているが、該
突起を球面状にしてもまた円柱状にしζも同等の効果を
得るごとができる。In the explanation of the present invention, the fine protrusions of the fingerprint stamping part are formed in the shape of a quadrangular pyramid, but the same effect can be obtained even if the protrusions are made spherical or cylindrical. can.
４はイメージセンサ、 １０は透明基板、 １０ｂは突起、 をそれぞれ表わす。4 is an image sensor, 10 is a transparent substrate; 10b is a protrusion; respectively.
５ａは指紋隆線、 １０ａは指紋押捺部、5a is a fingerprint ridge; 10a is a fingerprint stamping part;
第１図は本発明になる指紋像入力装置を説明する図、
第２図は従来の入力装置主要部を例示する原理図、
である。図において、
２は光源、 ３は結像光学系、イχ釆ｎ入力袈
置Ｊシを杏戸を今すホする２株玉里ｍ第 ２ 図FIG. 1 is a diagram illustrating a fingerprint image input device according to the present invention, and FIG. 2 is a principle diagram illustrating the main parts of a conventional input device. In the figure, 2 is a light source, 3 is an imaging optical system, and 2 is a light source, and 2 is an image-forming optical system.
Claims (1)
せしめた状態で該透明基板の裏面側所定位置から該透明
基板を通して上記被検体を光照射し、該被検体から反射
する画像光を画像検出部で指紋画像として検出する指紋
照合システムの指紋像入力装置において、 透明基板の上記指紋押捺部全面が、所定高さを有する凸
部を少なくとも上記画像検出部の解像分解能より細かい
ピッチで配置した凹凸面で形成されてなることを特徴と
した指紋像入力装置。[Scope of Claims] Light is irradiated onto the subject through the transparent substrate from a predetermined position on the back side of the transparent substrate while the subject is in contact with a fingerprint imprinted portion provided at a predetermined position on the transparent substrate. In a fingerprint image input device for a fingerprint matching system in which image light reflected from a specimen is detected as a fingerprint image by an image detection unit, the entire surface of the fingerprint imprinted portion of the transparent substrate has a convex portion having a predetermined height at least as high as that of the image detection unit. A fingerprint image input device characterized by being formed of an uneven surface arranged at a pitch finer than resolution.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1008117A JP2712469B2 (en) | 1989-01-17 | 1989-01-17 | Fingerprint image input device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1008117A JP2712469B2 (en) | 1989-01-17 | 1989-01-17 | Fingerprint image input device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02188888A true JPH02188888A (en) | 1990-07-24 |
| JP2712469B2 JP2712469B2 (en) | 1998-02-10 |
Family
ID=11684340
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1008117A Expired - Lifetime JP2712469B2 (en) | 1989-01-17 | 1989-01-17 | Fingerprint image input device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2712469B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6324020B1 (en) * | 1999-08-04 | 2001-11-27 | Secugen Corporation | Method and apparatus for reduction of trapezoidal distortion and improvement of image sharpness in an optical image capturing system |
| US6381347B1 (en) | 1998-11-12 | 2002-04-30 | Secugen | High contrast, low distortion optical acquistion system for image capturing |
| US7118031B2 (en) * | 2002-11-26 | 2006-10-10 | Diebold, Incorporated | Automated banking machine with improved resistance to fraud |
-
1989
- 1989-01-17 JP JP1008117A patent/JP2712469B2/en not_active Expired - Lifetime
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6381347B1 (en) | 1998-11-12 | 2002-04-30 | Secugen | High contrast, low distortion optical acquistion system for image capturing |
| US6324020B1 (en) * | 1999-08-04 | 2001-11-27 | Secugen Corporation | Method and apparatus for reduction of trapezoidal distortion and improvement of image sharpness in an optical image capturing system |
| US7118031B2 (en) * | 2002-11-26 | 2006-10-10 | Diebold, Incorporated | Automated banking machine with improved resistance to fraud |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2712469B2 (en) | 1998-02-10 |
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