Fingerprint image entry device of electrostatic capacitance sensing type

• US 6,055,324 A
• Filed: 06/24/1998
• Issued: 04/25/2000
• Est. Priority Date: 06/30/1997
• Status: Expired due to Term

• Current Assignee: Vista Peak Ventures LLC (Dominion Harbor Enterprises, LLC)
• Original Assignee: NEC Corporation
• Inventors: Fujieda, Ichiro
• Primary Examiner(s): Boudreau, Leo H.
• Assistant Examiner(s): Werner, Brian P.
• Application Number:
  US09/103,502
• Time in Patent Office: 671 Days
• Field of Search: 382/124-127, 382/312, 382/108, 382/319, 382/318, 382/315, 340/825.34, 356/71
• US Class Current: 382/124
• CPC Class Codes: G06V 40/1306 non-optical, e.g. ultrasonic or capacitive sensing

Abstract

Fingerprint image entry device having no ground electrode provided in a position with which a finger is in a direct contact, wherein accurate fingerprint image can be entered independently of the initial electrostatically charged condition of the finger. The device comprises an electrode which is in the form of mesh or comb for radiating a high frequency wave toward a finger, a plurality of signal sensing electrodes for forming electrostatic capacitance between the electrodes and the finger and a signal switching means for consecutively connecting each of these signal sensing electrodes to a signal sensing circuit.

Claims

1. A fingerprint image entry device comprising

a substrate having a surface with which a finger can be brought into contact via a protective layer;

a plurality of first electrodes which are two-dimensionally arrayed on said surface; and

a plurality of switching elements, each being provided correspondingly to one of said first electrodes, so that a fingerprint image is obtained by sensing the electrostatic capacitance formed between said finger and each of said first electrodes,

wherein said device comprises

a second electrode which is formed in the form of mesh or comb on the same surface as said first electrodes;

a signal generating circuit which is connected to said second electrode; and

means for controlling said switching elements to consecutively bringing said switching elements conductive for electrically connecting said first electrodes to a signal sensing circuit.

2. A fingerprint image entry device as defined in claim 1, wherein said substrate is formed of a dielectric substrate or crystal silicon wafer.

3. A fingerprint image entry device as defined in claim 1, wherein said switching elements are at least any one selected from the group consisting of transistors formed of thin film semiconductor or crystal silicon and back-to-back diodes.

4. A fingerprint image entry device as defined in claim 3, wherein said signal generating electrode has a shape of comb-teeth extending along said sensing unit in each row.

5. A fingerprint image entry device comprising

a substrate having a surface with which a finger can be brought into contact via a protective layer;

a plurality of first electrodes which are two-dimensionally arrayed on said surface; and

a plurality of switching elements, each being provided correspondingly to one of said first electrodes, so that a fingerprint image is obtained by sensing the electrostatic capacitance formed between said finger and each of said first electrodes,

wherein said device comprises

a second electrode which is formed in the form of a mesh or comb on the same surface as said first electrodes;

a signal sensing circuit which is connected to said second electrode; and

means for controlling said switching elements to consecutively bring said switching elements conductive for electrically connecting a high frequency signal generating circuit to said first electrode.

6. A fingerprint image entry device as defined in claim 5, wherein said substrate is formed of a dielectric substrate or crystal silicon wafer.

7. A fingerprint image entry device as defined in claim 5, wherein said switching elements are at least any one selected from the group consisting of transistors formed of thin film semiconductor or crystal silicon and back-to-back diodes.

8. A fingerprint image entry device comprising

a substrate having a surface with which a finger can be brought into contact via a protective layer;

a plurality of first electrodes which are two-dimensionally arrayed on said surface; and

a plurality of switching elements, one being provided correspondingly to each of said first electrodes, so that a fingerprint image is obtained by sensing the electrostatic capacitance formed between said finger and each of said first electrodes,

wherein said device comprises;

a plurality of electrodes which are formed in strips on the same surface as said first electrodes;

second switching elements, each for one of said second electrodes; and

means for controlling said first and second switching elements to electrically connect a high frequency signal generating circuit to said second electrodes by consecutively bringing said second switching elements conductive and to electrically connect a signal sensing circuit to said first electrodes by consecutively bringing said first switching elements conductive.

9. A fingerprint image entry device as defined in claim 8, wherein said substrate is formed of a dielectric substrate or crystal silicon wafer.

10. A fingerprint image entry device as defined in claim 8, wherein said switching elements are at least any one selected from the group consisting of transistors formed of thin film semiconductor or crystal silicon and back-to-back diodes.

11. A fingerprint image entry device comprising a substrate having a surface with which a finger can be brought into contact via a protective layer;

a plurality of first electrodes which are two-dimensionally arrayed on said surface; and

a plurality of switching elements, each being provided correspondingly to one of said first electrodes, so that a fingerprint image is obtained by sensing the electrostatic capacitance formed between said finger and each of said first electrodes,

wherein said device comprises;

a plurality of second electrodes which are formed in strips on said surface and are connected to said switching elements for controlling the conductive state of said switching elements;

means for applying a voltage, having a plurality of output terminals for consecutively applying a voltage to said plurality of second electrodes; and

a signal sensing circuit which is connected to said first electrodes via said switching elements, wherein outputs of the adjacent two output terminals of said voltage applying means are set to be simultaneously active for a given period of time.

12. A fingerprint image entry device as defined in claim 11, wherein said substrate is formed of a dielectric substrate or crystal silicon wafer.

13. A fingerprint image entry device as defined in claim 11, wherein said switching elements are at least any one selected from the group consisting of transistors formed of thin film semiconductor or crystal silicon and back-to-back diodes.

14. A fingerprint image entry device, wherein said device comprises:

a substrate having a surface on which a plurality of scanning signal leads and signal sensing leads are disposed so that they intersect each other at right angles;

switching elements and signal sensing electrodes in an area in which said scanning signal leads intersect said signal sensing leads;

said switching elements being connected between said signal sensing electrodes and said signal sensing leads, control terminals for said switching elements being connected to said scanning signal leads to define sensing units each for said area, said sensing units being two-dimensionally arrayed in a matrix form;

a signal generating electrode having openings, each surrounding the periphery of one of said signal sensing elements where said signal generating electrode is disposed on the same surface as said signal sensing elements;

means for consecutively making said plurality of scanning signal leads active to consecutively bring the switching elements into a conductive state; and

a signal sensing circuit which is connected to said signal sensing leads;

whereby said signal sensing electrodes in the row in which said scanning signal leads are made active are electrically connected to said signal sensing circuit via said signal sensing leads for applying a high frequency signal to said signal generating electrode to provide information on the terrain of the finger in each row.

15. A fingerprint image entry device as defined in claim 14, wherein said substrate is covered on its surface with a protective layer, to which said finger is brought into contact.

16. A fingerprint image entry device, wherein said device comprises:

a substrate having a surface on which a plurality of scanning signal leads and signal supplying leads are disposed so that they intersect each other at right angles;

switching elements and signal generating electrodes in an area in which said scanning signal leads intersect said signal supplying leads;

said switching elements being connected between said signal generating electrodes and said signal supplying leads, control terminals for said switching elements being connected to said scanning signal leads to define sensing units each for said area, said sensing units being two-dimensionally arrayed in a matrix form;

a signal sensing electrode having openings, each surrounding the periphery of one of said signal generating electrodes where said signal sensing electrode is disposed on the same surface as said signal generating electrodes;

means for consecutively making said plurality of scanning signal leads active to consecutively bring the switching elements in each row into a conductive state; and

means for consecutively and electrically connecting said plurality of signal supply leads to a high frequency signal generating source; and

a signal sensing circuit which is connected to said signal sensing electrodes;

wherein a high frequency signal is applied via the signal supplying leads in each consecutively selected column to each of said signal generating electrodes in a row in which said scanning signal lead is made active, so that information on the terrain of the finger in said each row and column is obtained through said signal sensing electrodes and said signal sensing circuit.

17. A fingerprint image entry device as defined in claim 16, wherein said substrate is covered on its surface with a protective layer, to which said finger is brought into contact.

18. A fingerprint image entry device, wherein said device comprises:

a substrate having a surface on which a plurality of signal scanning signal leads and signal sensing leads are disposed so that they intersect each other at right angles;

switching elements and signal sensing electrodes in an area in which said scanning signal leads intersect said signal sensing leads;

said switching elements being connected between said signal sensing electrodes and said signal sensing leads, control terminals for said switching elements being connected to said scanning signal leads to define sensing units each for said area, said sensing units being two-dimensionally arrayed in a matrix form;

a signal generating electrode which is disposed on the same surface and along a plurality of said signal sensing electrodes in each row;

means for consecutively making said plurality of scanning signal leads active to consecutively bring the switching elements in each row into a conductive state; and

a signal sensing circuit which is connected to said signal sensing leads;

means for consecutively and electrically connecting said plurality of signal generating electrodes to a high frequency signal generating circuit when the scanning signal leads are made active;

wherein said signal sensing electrodes in the row in which said scanning signal leads are made active are electrically connected to said signal sensing circuit via the signal sensing leads for applying a high frequency signal to said signal generating electrode to provide information on the terrain of the finger in each row.

19. A fingerprint image entry device as defined in claim 18, wherein said substrate is covered on its surface with a protective layer, to which said finger is brought into contact.

20. A fingerprint image entry device, wherein said device comprises

a substrate having a surface on which a plurality of scanning signal scanning leads and signal sensing leads are disposed so that they intersect each other at right angles;

switching elements and signal sensing electrodes in an area in which said scanning signal leads intersect said signal sensing leads;

said switching elements being connected between said signal sensing electrodes and said signal sensing leads, the control terminals for said switching elements being connected to said scanning signal leads to define sensing units each for said area, said sensing units being two-dimensionally arrayed in a matrix form;

signal generating electrodes disposed along said plurality of signal sensing electrodes, said signal generating electrodes being also used as said scanning signal leads;

a signal sensing circuit which is connected to said signal sensing leads;

said plurality of signal generating electrodes being also used as said scanning signal leads; and

means for consecutively making said signal generating electrodes serving as said scanning signal leads in each row to generate signals having an active duration which overlaps between neighboring rows.