JP3270927B2 - Sensor circuit for surface shape recognition - Google Patents
Sensor circuit for surface shape recognitionInfo
- Publication number
- JP3270927B2 JP3270927B2 JP23385898A JP23385898A JP3270927B2 JP 3270927 B2 JP3270927 B2 JP 3270927B2 JP 23385898 A JP23385898 A JP 23385898A JP 23385898 A JP23385898 A JP 23385898A JP 3270927 B2 JP3270927 B2 JP 3270927B2
- Authority
- JP
- Japan
- Prior art keywords
- potential
- capacitance
- surface shape
- terminal
- switch
- 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.)
- Expired - Lifetime
Links
- 239000004065 semiconductor Substances 0.000 claims description 10
- 239000000758 substrate Substances 0.000 claims description 9
- 238000001514 detection method Methods 0.000 description 18
- 230000003071 parasitic effect Effects 0.000 description 13
- 238000005259 measurement Methods 0.000 description 9
- 239000003990 capacitor Substances 0.000 description 6
- 238000010586 diagram Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 230000008878 coupling Effects 0.000 description 3
- 238000010168 coupling process Methods 0.000 description 3
- 238000005859 coupling reaction Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000001681 protective effect Effects 0.000 description 3
- 239000004020 conductor Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000007274 generation of a signal involved in cell-cell signaling Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
Landscapes
- Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
- Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)
- Image Input (AREA)
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、表面形状認識用セ
ンサ回路に関するものであり、特に人間の指紋や動物の
鼻紋などの微細な凹凸を感知する容量形センサ回路に関
する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor circuit for recognizing a surface shape, and more particularly to a capacitive sensor circuit for detecting minute irregularities such as a human fingerprint and an animal nose pattern.
【０００２】[0002]
【従来の技術】指紋のパターンの検出を主な応用例とし
た表面形状認識用センサ回路としては、「‘ＩＳＳＣＣ
ＤＩＧＥＳＴ ＯＦ ＴＥＣＨＮＩＣＡＬ ＰＡＰＥ
ＲＳ’ＦＥＢＲＵＡＲＹ １９９８ ｐｐ．２８４〜２
８５」に記載されている回路がある。このセンサ回路
は、図６に示すようにＬＳＩチップ３０の上に２次元に
配列された小さなセンサ素子２０の電極と、この電極上
に形成された絶縁膜を介して触れた指４０の皮膚との間
に形成される静電容量を検出して、指紋の凹凸パターン
を感知するものである。2. Description of the Related Art As a sensor circuit for surface shape recognition which is mainly applied to the detection of a fingerprint pattern, "'ISSCC" is known.
DIGEST OF TECHNICAL PAPE
RS'FEBRARY 1998 pp. 284-2
85 ". This sensor circuit includes, as shown in FIG. 6, the electrodes of the small sensor elements 20 arranged two-dimensionally on the LSI chip 30 and the skin of the finger 40 touched via an insulating film formed on the electrodes. It detects the capacitance formed between them, and senses the concavo-convex pattern of the fingerprint.
【０００３】指紋の凹凸により形成される容量の値が異
なるため、この容量差を検出することで指紋の凹凸を感
知することができる。このようにな測定対象物の表面形
状の凹凸を反映した容量値を検出するセンサ回路の実現
例を図４に示す。図４において、Ｃｆは測定対象物の表
面形状の凹凸を反映した容量である。Ｃｓは節点Ｎ２の
電位を変化させための容量、Ｃｐは寄生容量である。ま
た、Ｖｐは後述のスイッチＳＷの閉結により節点Ｎ２に
与えられる電位、Ｖｓは図中の節点Ｎ４の電位である。
なお、節点Ｎ３は指の皮膚にあたる。そのため、節点Ｎ
３には特定の電位をセンサ回路からは与えていないが、
ある電位に固定されていると考えてよい。Ｐはスイッチ
ＳＷを制御する信号である。スイッチＳＷは例えばＭＯ
Ｓトランジスタを用いて実現することができる。なお、
１０は検出回路である。Since the value of the capacitance formed by the unevenness of the fingerprint is different, the unevenness of the fingerprint can be sensed by detecting the difference in the capacitance. FIG. 4 shows an implementation example of a sensor circuit that detects a capacitance value that reflects such irregularities in the surface shape of the measurement object. In FIG. 4, Cf is a capacitance reflecting the irregularities of the surface shape of the measurement object. Cs is a capacitance for changing the potential of the node N2, and Cp is a parasitic capacitance. Vp is a potential applied to a node N2 by closing a switch SW described later, and Vs is a potential of a node N4 in the figure.
The node N3 corresponds to the skin of the finger. Therefore, node N
No specific potential is given to sensor 3 from the sensor circuit,
It may be considered that the potential is fixed at a certain potential. P is a signal for controlling the switch SW. The switch SW is, for example, MO
This can be realized using an S transistor. In addition,
10 is a detection circuit.
【０００４】次に図４に示したセンサ回路の動作を図５
のタイミングチャートに基づいて説明する。まず、図５
（ａ）において制御信号ＰをＨｉｇｈレベルにすること
によりスイッチＳＷを導通状態にし、図４の節点Ｎ２の
電位を電圧ＶＰに設定する。この動作をプリチャージと
呼ぶ。節点Ｎ２をブリチャージ後、制御信号ＰをＬｏｗ
レベルにしてスイッチＳＷを非導通状態にした後、Ｖｓ
の電位を変化させる。Next, the operation of the sensor circuit shown in FIG.
A description will be given based on the timing chart of FIG. First, FIG.
In FIG. 4A, the switch SW is turned on by setting the control signal P to a high level, and the potential of the node N2 in FIG. 4 is set to the voltage VP. This operation is called precharge. After precharging the node N2, the control signal P is changed to Low.
Level to make the switch SW non-conductive, then Vs
Is changed.
【０００５】ここで、Ｖｓの変化量を△Ｖｓとすると、
節点Ｎ２の電位は容量Ｃｓによる容量結合に基づいて変
化する。節点Ｎ２の電位の変化量△ＶN2は、 △ＶN2＝Ｃｓ／（Ｃｆ＋Ｃｐ＋Ｃｓ）＊△Ｖｓ （１） となる。ここで測定対象物の表面形状が凹の場合のＣｆ
の値をＣｆ０、表面形状が凸の場合のＣｆの値をＣｆ１
とすると（この場合、Ｃｆ０＜Ｃｆ１となる）、表面形
状の違いによる変化量の差△Ｖは、 ΔＶ＝ （Ｃｓ／（Ｃｆ０＋Ｃｐ＋Ｃｓ）−Ｃｓ／（Ｃｆ１＋Ｃｐ＋Ｃｓ））＊△Ｖｓ （２） となる。したがって、測定対象物の表面形状の違いによ
る変化量の差△Ｖを検出回路１０により判定することで
測定対象物の表面形状の凹凸を検出することができる。Here, assuming that the variation of Vs is ΔVs,
The potential of the node N2 changes based on capacitive coupling by the capacitance Cs. The amount of change ΔVN2 in the potential of the node N2 is ΔVN2 = Cs / (Cf + Cp + Cs) * ΔVs (1) Here, Cf when the surface shape of the measurement object is concave
Is Cf0, and the value of Cf when the surface shape is convex is Cf1.
Then (in this case, Cf0 <Cf1), the difference ΔV in the variation due to the difference in the surface shape is ΔV = (Cs / (Cf0 + Cp + Cs) −Cs / (Cf1 + Cp + Cs)) * △ Vs (2) Therefore, the unevenness of the surface shape of the measurement object can be detected by determining the difference ΔV of the variation due to the difference in the surface shape of the measurement object by the detection circuit 10.
【０００６】[0006]
【発明が解決しようとする課題】しかしながら、従来の
表面形状認識用センサ回路では、寄生容量Ｃｐおよび節
点Ｎ２の電位を変化させための容量Ｃｓの影響により、
表面形状の違いによる変化量の差△Ｖをあまり大きくで
きないという問題がある。ここで、検出回路１０の製造
ばらつきや電源ノイズ等を考慮すると、表面形状の違い
による変化量の差△Ｖは大きいことが望ましい。容量Ｃ
ｓをある程度大きくすることで変化量の差△Ｖを大きく
することができるが、容量Ｃｓは寄生容量Ｃｐと並列に
接続されているために寄生容量Ｃｐと同じ影響を与えて
しまい、必要以上に容量Ｃｓを大きくすると、逆に表面
形状の違いによる変化量の差△Ｖは小さくなってしま
う。また、寄生容量Ｃｐの値によって最適な容量Ｃｓの
値が異なるため、あらかじめ寄生容量Ｃｐの値を予測し
て容量Ｃｓの大きさを設計しなければならない。実際
は、寄生容量Ｃｐの見積り値と実際の値は異なるため、
容量Ｃｓを最適値にすることは難しい。また、寄生容量
Ｃｐの見積り値と実際の値が大きく異なると、センサ回
路が所望の通り動作しなくなってしまう。However, in the conventional sensor circuit for recognizing the surface shape, the influence of the parasitic capacitance Cp and the capacitance Cs for changing the potential of the node N2 causes the problem.
There is a problem that the difference ΔV in the amount of change due to the difference in the surface shape cannot be made so large. Here, in consideration of manufacturing variations of the detection circuit 10, power supply noise, and the like, it is desirable that the difference ΔV in the amount of change due to the difference in surface shape is large. Capacity C
By increasing s to some extent, the difference ΔV in the amount of change can be increased. However, since the capacitance Cs is connected in parallel with the parasitic capacitance Cp, the capacitance Cs has the same effect as the parasitic capacitance Cp. When the capacitance Cs is increased, the difference ΔV in the amount of change due to the difference in the surface shape is reduced. Further, since the optimum value of the capacitance Cs differs depending on the value of the parasitic capacitance Cp, it is necessary to design the size of the capacitance Cs by predicting the value of the parasitic capacitance Cp in advance. Actually, since the estimated value of the parasitic capacitance Cp is different from the actual value,
It is difficult to make the capacitance Cs an optimum value. Also, if the estimated value of the parasitic capacitance Cp and the actual value are significantly different, the sensor circuit will not operate as desired.
【０００７】したがって、従来の表面形状認識用センサ
回路では、表面形状に対応した大きな信号差を発生する
ことが困難であった。特に指紋のように微小な凹凸を検
出しようとする場合、変化量の差△Ｖは非常に小さくな
ってしまう。この結果、検出回路の製造ばらつきや電源
ノイズ等により指紋パターンの検出精度が低下したり、
または検出できないという問題があった。本発明は、上
述の問題を解決するべくなされたものでありその目的と
するところは、指紋のような微小な凹凸を、大きな信号
差として発生させることにある。Therefore, it has been difficult for the conventional sensor circuit for surface shape recognition to generate a large signal difference corresponding to the surface shape. In particular, when trying to detect minute unevenness like a fingerprint, the difference ΔV in the amount of change becomes very small. As a result, the detection accuracy of the fingerprint pattern may be reduced due to manufacturing variations of the detection circuit, power supply noise, or the like,
Or there was a problem that it could not be detected. The present invention has been made to solve the above-described problem, and an object of the present invention is to generate minute unevenness such as a fingerprint as a large signal difference.
【０００８】[0008]
【課題を解決するための手段】このような課題を解決す
るために本発明は、測定対象物の表面凹凸に応じて第１
の端子と第２の端子間の容量が変化する容量センサ素子
と、第２の端子に接続され容量センサ素子の容量の変化
を検出する検出手段と、第２の端子と外部電位との接続
をオン・オフするスイッチと、第１の端子の電位を制御
するとともに、スイッチのオン・オフを制御する制御手
段とを備え、制御手段は、第１の端子を一定電位にして
スイッチをオンして容量センサ素子を充電した後、スイ
ッチをオフするとともに第１の端子の電位を前記一定電
位とは異なる電位に変化させ、検出手段は、スイッチが
オフになり第１の端子の電位が一定電位とは異なる電位
に変化したときの第２の端子の電位を検出するようにし
たものである。また、半導体基板と、半導体基板上に形
成された少なくとも１つの下部電極と、半導体基板上に
容量センサ素子毎に形成された導電性を有する支持部材
と、支持部材上に形成された上部電極とを備え、上記容
量センサ素子の第１及び第２の端子はそれぞれ上部電極
及び下部電極に接続されるとともに、制御手段は、上部
電極及び下部電極の電位を個別に制御するものである。In order to solve such a problem, the present invention provides a first method according to the surface unevenness of an object to be measured.
A capacitance sensor element in which the capacitance between the first terminal and the second terminal changes, detection means connected to the second terminal for detecting a change in the capacitance of the capacitance sensor element, and connection between the second terminal and the external potential. A switch for turning on and off, and control means for controlling the potential of the first terminal and for controlling on and off of the switch, wherein the control means sets the first terminal to a constant potential and turns on the switch. After charging the capacitance sensor element, the switch is turned off and the potential of the first terminal is changed to a potential different from the constant potential, and the detecting means turns off the switch to change the potential of the first terminal to the constant potential. Is to detect the potential of the second terminal when it changes to a different potential. A semiconductor substrate, at least one lower electrode formed on the semiconductor substrate, a conductive support member formed for each capacitance sensor element on the semiconductor substrate, and an upper electrode formed on the support member. Wherein the first and second terminals of the capacitive sensor element are connected to an upper electrode and a lower electrode, respectively, and the control means individually controls the potentials of the upper electrode and the lower electrode.
【０００９】[0009]
【発明の実施の形態】本発明に係る表面形状認識用セン
サ回路は、センサ素子を構成する容量の複数の電極の電
位を個別に制御する手段を有することを主な特徴とす
る。そしてこうした手段を備えることにより、測定対象
物の表面形状を反映した大きな信号差を発生する手段を
提供することができる。DESCRIPTION OF THE PREFERRED EMBODIMENTS A surface shape recognition sensor circuit according to the present invention is characterized mainly by having means for individually controlling the potentials of a plurality of electrodes of a capacitor constituting a sensor element. By providing such means, it is possible to provide means for generating a large signal difference reflecting the surface shape of the measurement object.
【００１０】以下、本発明について図面を参照して説明
する。図１は本発明に係る表面形状認識用センサ回路の
構成を示す図であり、半導体基板上に二次元配列された
図６に示すセンサアレイ（ＬＳＩ）３０のうち１つのセ
ンサ素子２０の断面を示すものである。Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration of a sensor circuit for surface shape recognition according to the present invention. FIG. 1 shows a cross section of one sensor element 20 of a sensor array (LSI) 30 shown in FIG. It is shown.
【００１１】図１において、１は下部電極、２は金属
膜、３は支持部材、４は上部電極、５は半導体基板、６
は保護膜、１０は検出回路、ＳＷはスイッチである。こ
こで、各センサ素子２０は支持部材３により分離され
る。なお、図１において、Ｃｆは上部電極４と下部電極
１間の容量であり、保護膜６上にある測定対象物の表面
形状の凹凸を反映した容量である。また、Ｃｐは寄生容
量、Ｖｐは図中の節点Ｎ１に与えられる外部電位であ
る。さらに、ＰはスイッチＳＷの制御信号である。スイ
ッチＳＷは例えばＭＯＳトランジスタを用いて実現する
ことができる。また、１０は検出回路、１１は制御手段
である。図１に示すセンサ回路は、図４の従来回路に対
し、節点の電位を変化させための容量Ｃｓを削除した点
が異なる。また、容量Ｃｆの節点Ｎ１に接続している下
部電極１とは異なる、もう一方の上部電極４の電位も制
御している点も異なる。In FIG. 1, 1 is a lower electrode, 2 is a metal film, 3 is a supporting member, 4 is an upper electrode, 5 is a semiconductor substrate, 6
Is a protective film, 10 is a detection circuit, and SW is a switch. Here, each sensor element 20 is separated by the support member 3. In FIG. 1, Cf is a capacitance between the upper electrode 4 and the lower electrode 1, and is a capacitance reflecting the unevenness of the surface shape of the measurement object on the protective film 6. Further, Cp is a parasitic capacitance, and Vp is an external potential applied to a node N1 in the figure. Further, P is a control signal for the switch SW. The switch SW can be realized using, for example, a MOS transistor. Reference numeral 10 denotes a detection circuit, and reference numeral 11 denotes a control unit. The sensor circuit shown in FIG. 1 is different from the conventional circuit in FIG. 4 in that a capacitor Cs for changing the potential of the node is eliminated. Further, it differs from the lower electrode 1 connected to the node N1 of the capacitor Cf and also controls the potential of the other upper electrode 4.
【００１２】図１のセンサ回路では、容量Ｃｆを形成す
るために、本出願人の別途出願である特願平１０−５３
９１１号に記載されている方法を用いた場合を示してい
るが、本発明はこれに限定されるものではない。この特
願平１０−５３９１１号においては、容量ＣｆはＬＳＩ
チップの上に変形可能な上部電極４と半導体基板５上に
配置された下部電極１とにより構成される。また、上部
電極４は導電性を有した支持部材３によって支えられて
いる。そして、測定対象物の表面形状の凹凸に対応して
上部電極４が変形するため、容量Ｃｆの値が変化する。
この容量Ｃｆの値の変化は、容量Ｃｆが接続された下部
電極１及び節点Ｎ１を介して検出回路１０により検出さ
れる。なお、容量Ｃｆの上部電極４の電位の制御は、導
電体である支持部材３の電位を制御することで可能にな
る。即ち、支持部材３と接続される金属膜２に、電圧Ｖ
ｓを与えることで上部電極４の電位を制御することがで
きる。In the sensor circuit shown in FIG. 1, in order to form the capacitance Cf, the applicant of the present invention has filed another Japanese Patent Application No. 10-53.
911 is shown, but the present invention is not limited to this. In this Japanese Patent Application No. 10-53911, the capacitance Cf is an LSI.
It comprises an upper electrode 4 deformable on a chip and a lower electrode 1 arranged on a semiconductor substrate 5. Further, the upper electrode 4 is supported by the support member 3 having conductivity. Then, since the upper electrode 4 is deformed in accordance with the unevenness of the surface shape of the measurement object, the value of the capacitance Cf changes.
This change in the value of the capacitance Cf is detected by the detection circuit 10 via the lower electrode 1 to which the capacitance Cf is connected and the node N1. The potential of the upper electrode 4 of the capacitor Cf can be controlled by controlling the potential of the support member 3 which is a conductor. That is, the voltage V is applied to the metal film 2 connected to the support member 3.
By giving s, the potential of the upper electrode 4 can be controlled.
【００１３】図１に示したセンサ回路の動作を、図２の
タイミングチャートに基づいて説明する。まず、制御手
段１１は、図２（ｂ）の時点で電圧Ｖｓを一定電位と
し、これを金属膜２及び支持部材３を介して上部電極４
に与える。次に制御手段１１は、図２（ａ）の時点で
制御信号ＰをＨｉｇｈレベルにしてスイッチＳＷを導通
状態にし、図１に示す節点Ｎ１の電位を外部電圧Ｖｐに
プリチャージして、容量Ｃｆを充電する。節点Ｎ１をプ
リチャージ後、制御手段１１は図２（ａ）の時点で制
御信号ＰをＬｏｗレベルにしてスイッチＳＷを非導通状
態にし、さらにＶｓの電位を図２（ｂ）に示すように前
記一定電位からΔＶｓ分変化させる。ここで、電圧Ｖｓ
の変化量が△Ｖｓである場合、節点Ｎ１の電位は容量Ｃ
ｆによる容量結合により変化し、節点Ｎ１の電位の変化
量は Ｃｆ／（Ｃｆ＋Ｃｐ）＊△Ｖｓ （３） となる。The operation of the sensor circuit shown in FIG. 1 will be described with reference to the timing chart of FIG. First, the control means 11 sets the voltage Vs to a constant potential at the time of FIG. 2B, and applies this to the upper electrode 4 via the metal film 2 and the support member 3.
Give to. Next, the control means 11 sets the control signal P to the high level at the time of FIG. 2A to turn on the switch SW, precharges the potential of the node N1 shown in FIG. 1 to the external voltage Vp, and sets the capacitance Cf Charge. After precharging the node N1, the control means 11 sets the control signal P to the low level at the time of FIG. 2 (a) to turn off the switch SW, and further sets the potential of Vs as shown in FIG. 2 (b). The potential is changed from the constant potential by ΔVs. Here, the voltage Vs
Is △ Vs, the potential of the node N1 becomes the capacitance C
f, and the amount of change in the potential of the node N1 becomes Cf / (Cf + Cp) * △ Vs (3).
【００１４】ここで、表面形状が凹の場合のＣｆの値を
Ｃｆ０、表面形状が凸の場合のＣｆの値をＣｆ１とする
と（この場合、Ｃｆ０＜Ｃｆ１となる）、表面形状の違
いによる変化量の差△Ｖは、 ΔＶ＝ （Ｃｆ１／（Ｃｆ１＋Ｃｐ）−Ｃｆ０／（Ｃｆ０＋Ｃｐ））＊△Ｖｓ （４） となる。Here, if the value of Cf when the surface shape is concave is Cf0 and the value of Cf when the surface shape is convex is Cf1 (in this case, Cf0 <Cf1), the change due to the difference in the surface shape is obtained. The amount difference ΔV is as follows: ΔV = (Cf1 / (Cf1 + Cp) −Cf0 / (Cf0 + Cp)) * ΔVs (4)
【００１５】そして、表面形状の違いによる変化量の差
△Ｖを検出回路１０で検出して判定することにより、表
面形状の凹凸を検出する。このように本センサ回路は、
容量Ｃｆに接続される複数の電極の電位を、検出のタイ
ミングに合わせて変化させることにより、容量Ｃｆの容
量変化に対応する電圧変化を大きくして検出感度を高め
るようにしたものである。ここで、表面形状の違いによ
る変化量の差△Ｖの大きさを従来例と比較した場合の例
を図３に示す。図３において、横軸はＣｐとＣｆ０との
比である。図３からわかるように、本発明のセンサ回路
の方が表面形状の違いによる変化量の差△Ｖが大きくな
っていることがわかる。したがって、従来の表面形状認
識用センサ回路に比べて表面形状の凹凸を反映した信号
変化の差を大きくすることができる。なお、表面形状の
違いによる変化量の差△Ｖは、寄生容量Ｃｐを小さくし
た方がより大きくなることは図３から明らかである。The detection circuit 10 detects and determines the difference ΔV in the variation due to the difference in the surface shape, thereby detecting the unevenness of the surface shape. Thus, this sensor circuit is
By changing the potentials of a plurality of electrodes connected to the capacitor Cf in accordance with the detection timing, the voltage change corresponding to the capacitance change of the capacitor Cf is increased to increase the detection sensitivity. Here, FIG. 3 shows an example in which the magnitude of the difference ΔV in the variation due to the difference in the surface shape is compared with that of the conventional example. In FIG. 3, the horizontal axis is the ratio between Cp and Cf0. As can be seen from FIG. 3, the sensor circuit of the present invention has a larger difference ΔV in the variation due to the difference in the surface shape. Therefore, the difference in signal change reflecting the unevenness of the surface shape can be increased as compared with the conventional sensor circuit for surface shape recognition. It is clear from FIG. 3 that the difference ΔV in the amount of change due to the difference in the surface shape increases as the parasitic capacitance Cp decreases.
【００１６】このように、本発明の表面形状認識用セン
サ回路では、Ｃｆによる容量結合を利用して測定対象物
表面形状の凹凸を反映した信号を発生させるため、従来
例に比べて表面形状の凹凸を反映した信号変化の差を大
きくすることができる。また、容量Ｃｓが不要となるこ
とから、設計時に寄生容量Ｃｐを見積ることが不要にな
り、したがって寄生容量Ｃｐを見積もって適切な容量Ｃ
ｓを設計する煩雑さをなくすことができる。この結果、
本表面形状認識用センサ回路は、検出回路１０の製造ば
らつきや電源ノイズ等によって指紋パターンの検出精度
が低下したり、検出できなくなるといった問題を防ぐこ
とができる。As described above, in the surface shape recognition sensor circuit of the present invention, a signal reflecting the unevenness of the surface shape of the object to be measured is generated by utilizing the capacitive coupling by Cf. The difference in signal change reflecting the unevenness can be increased. Further, since the capacitance Cs is not required, it is not necessary to estimate the parasitic capacitance Cp at the time of design.
The complexity of designing s can be eliminated. As a result,
The sensor circuit for surface shape recognition can prevent a problem that the detection accuracy of the fingerprint pattern is reduced or cannot be detected due to manufacturing variations of the detection circuit 10, power supply noise, or the like.
【００１７】[0017]
【発明の効果】以上説明したように本発明によれば、上
部電極（第１の端子）と下部電極（第２の端子）間の容
量センサ素子Ｃｆによる容量結合を利用して測定対象物
の表面形状の凹凸を反映した信号を発生させるため、従
来例に比べて表面形状の凹凸を反映した信号変化の差を
大きくすることができる。また、節点の電位を変化させ
ための容量Ｃｓが不要になるため、設計時に寄生容量Ｃ
ｐを見積もって適切なＣｓを設計する煩雑さをなくすこ
とができる。このため、検出回路の製造ばらつきや電源
ノイズ等によって指紋パターンの検出精度が低下した
り、検出できなくなるという問題を防ぐことができる効
果がある。特に指紋のように微小な凹凸を検出する表面
形状認識用センサに本発明のセンサ回路を適用すれば、
効果は大である。As described above, according to the present invention, the object to be measured is measured by utilizing the capacitive coupling between the upper electrode (first terminal) and the lower electrode (second terminal) by the capacitive sensor element Cf. Since a signal reflecting the irregularities of the surface shape is generated, the difference in signal change reflecting the irregularities of the surface shape can be increased as compared with the conventional example. Further, since the capacitance Cs for changing the potential of the node is not required, the parasitic capacitance C
The complexity of estimating p and designing an appropriate Cs can be eliminated. For this reason, there is an effect that it is possible to prevent a problem that the detection accuracy of the fingerprint pattern is reduced or cannot be detected due to manufacturing variations of the detection circuit, power supply noise, or the like. In particular, if the sensor circuit of the present invention is applied to a surface shape recognition sensor that detects minute irregularities like a fingerprint,
The effect is great.
【図１】 本発明のセンサ回路の構成を示す図である。FIG. 1 is a diagram showing a configuration of a sensor circuit of the present invention.
【図２】 図１のセンサ回路の動作を示すタイムチャー
トである。FIG. 2 is a time chart illustrating an operation of the sensor circuit of FIG. 1;
【図３】 測定対象物の表面形状の凹凸を反映した信号
変化の差を本発明のセンサ回路と従来回路とで比較した
場合のグラフである。FIG. 3 is a graph showing a comparison between a sensor circuit according to the present invention and a conventional circuit in terms of a difference in signal change reflecting unevenness of a surface shape of a measurement object.
【図４】 従来回路の構成を示す図である。FIG. 4 is a diagram showing a configuration of a conventional circuit.
【図５】 従来回路の動作を示すタイムチャートであ
る。FIG. 5 is a time chart showing the operation of the conventional circuit.
【図６】 センサアレイの構成を示す図である。FIG. 6 is a diagram showing a configuration of a sensor array.
１…下部電極、２…金属膜、３…支持部材、４…上部電
極、５…半導体基板、６…保護膜、１０…検出回路、１
１…制御手段、２０…センサ素子、Ｖｐ，Ｖｓ…電位、
ΔＶｓ…電位の変化量、ΔＶ…電位の変化量の差、Ｎ１
〜Ｎ４…節点、Ｃｆ…容量センサ素子、Ｃｆ０…表面形
状が凹の場合の容量センサ素子の容量、Ｃｆ１…表面形
状が凸の場合の容量センサ素子の容量、Ｃｐ…寄生容
量、Ｃｓ…信号発生に用いる容量。DESCRIPTION OF SYMBOLS 1 ... Lower electrode, 2 ... Metal film, 3 ... Support member, 4 ... Upper electrode, 5 ... Semiconductor substrate, 6 ... Protective film, 10 ... Detection circuit, 1
1 ... control means, 20 ... sensor element, Vp, Vs ... potential,
ΔVs... Potential change amount, ΔV... Potential change amount difference, N1
ＮN4 ... node, Cf ... capacitance sensor element, Cf0 ... capacitance of capacitance sensor element when surface shape is concave, Cf1 ... capacity of capacitance sensor element when surface shape is convex, Cp ... parasitic capacitance, Cs ... signal generation Capacity used for
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭58−27277（ＪＰ，Ａ) 特開 平２−304613（ＪＰ，Ａ) 特開 平４−231803（ＪＰ，Ａ) 特開 平５−215625（ＪＰ，Ａ) 特開 平６−232343（ＪＰ，Ａ) 特開 平８−44493（ＪＰ，Ａ) 特開 平８−305832（ＪＰ，Ａ) 特開 平９−126918（ＪＰ，Ａ) 特開 平９−218006（ＪＰ，Ａ) 特開 平11−118415（ＪＰ，Ａ) 特開 平11−155837（ＪＰ，Ａ) 特開 平11−261015（ＪＰ，Ａ) 特表 平11−508806（ＪＰ，Ａ) 特表2000−513839（ＪＰ，Ａ) 特表2000−514227（ＪＰ，Ａ) 米国特許4353056（ＵＳ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) G01B 7/28 A61B 5/00 G06F 3/00 G06T 1/00 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-58-27277 (JP, A) JP-A-2-304613 (JP, A) JP-A-4-231803 (JP, A) JP-A-5-27 215625 (JP, A) JP-A-6-232343 (JP, A) JP-A-8-44493 (JP, A) JP-A-8-305832 (JP, A) JP-A-9-126918 (JP, A) JP-A-9-218006 (JP, A) JP-A-11-118415 (JP, A) JP-A-11-1555837 (JP, A) JP-A-11-261015 (JP, A) Table 11-508806 (JP, A) JP 2000-513839 (JP, A) JP 2000-514227 (JP, A) US Patent 4,353,056 (US, A) (58) Fields investigated (Int. Cl. 7 , DB name) G01B 7/28 A61B 5/00 G06F 3/00 G06T 1/00
Claims (2)
子と第２の端子間の容量が変化する容量センサ素子と、 前記第２の端子に接続され前記容量センサ素子の容量の
変化を検出する検出手段と、 前記第２の端子と外部電位との接続をオン・オフするス
イッチと、 前記第１の端子の電位を制御するとともに、前記スイッ
チのオン・オフを制御する制御手段とを備え、 前記制御手段は、前記第１の端子を一定電位にして前記
スイッチをオンして前記容量センサ素子を充電した後、
前記スイッチをオフするとともに前記第１の端子の電位
を前記一定電位とは異なる電位に変化させ、 前記検出手段は、前記スイッチがオフになり前記第１の
端子の電位が前記一定電位とは異なる電位に変化したと
きの前記第２の端子の電位を検出することを特徴とする
表面形状認識用センサ回路。1. A capacitance sensor element in which a capacitance between a first terminal and a second terminal changes according to a surface unevenness of an object to be measured, and a capacitance change of the capacitance sensor element connected to the second terminal. A switch for turning on / off the connection between the second terminal and an external potential; a control means for controlling the potential of the first terminal and controlling on / off of the switch And the control unit charges the capacitance sensor element by turning on the switch by setting the first terminal to a constant potential,
Turning off the switch and changing the potential of the first terminal to a potential different from the constant potential, wherein the detecting means turns off the switch and the potential of the first terminal is different from the constant potential A sensor circuit for recognizing a surface shape, which detects a potential of the second terminal when the potential changes to a potential.
も１つの下部電極と、前記半導体基板上に前記容量セン
サ素子毎に形成された導電性を有する支持部材と、前記
支持部材上に形成された上部電極とを備え、前記容量セ
ンサ素子の第１及び第２の端子はそれぞれ前記上部電極
及び下部電極に接続されるとともに、前記制御手段は、
前記上部電極及び下部電極の電位を個別に制御すること
を特徴とする表面形状認識用センサ回路。2. The semiconductor device according to claim 1, further comprising: a semiconductor substrate; at least one lower electrode formed on the semiconductor substrate; and a conductive supporting member formed on the semiconductor substrate for each of the capacitance sensor elements. And an upper electrode formed on the support member, wherein the first and second terminals of the capacitive sensor element are connected to the upper electrode and the lower electrode, respectively, and the control means includes:
A sensor circuit for recognizing a surface shape, wherein potentials of the upper electrode and the lower electrode are individually controlled.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23385898A JP3270927B2 (en) | 1998-08-20 | 1998-08-20 | Sensor circuit for surface shape recognition |
| EP99250215A EP0969477B1 (en) | 1998-07-02 | 1999-07-01 | Small capacitance change detection device |
| DE69933339T DE69933339T8 (en) | 1998-07-02 | 1999-07-01 | Detection device for small capacity changes |
| US09/347,240 US6438257B1 (en) | 1998-07-02 | 1999-07-02 | Small capacitance change detection device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23385898A JP3270927B2 (en) | 1998-08-20 | 1998-08-20 | Sensor circuit for surface shape recognition |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2000065514A JP2000065514A (en) | 2000-03-03 |
| JP3270927B2 true JP3270927B2 (en) | 2002-04-02 |
Family
ID=16961683
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP23385898A Expired - Lifetime JP3270927B2 (en) | 1998-07-02 | 1998-08-20 | Sensor circuit for surface shape recognition |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3270927B2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7123026B2 (en) | 2001-01-23 | 2006-10-17 | Nippon Telegraph And Telephone Corporation | Surface shape recognition sensor and method of manufacturing the same |
| EP1772702A4 (en) | 2004-07-23 | 2011-10-05 | Nippon Telegraph & Telephone | Surface shape recognizing sensor device |
| JP4968121B2 (en) | 2008-03-10 | 2012-07-04 | 富士通セミコンダクター株式会社 | Capacitance sensor |
| JP2011133964A (en) | 2009-12-22 | 2011-07-07 | Sanyo Electric Co Ltd | Capacitance discrimination circuit and touch switch equipped with the same |
-
1998
- 1998-08-20 JP JP23385898A patent/JP3270927B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JP2000065514A (en) | 2000-03-03 |
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