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Capacitor detecting device and its driving method, fingerprint sensor and biological identification device

A detection device, electrostatic capacitance technology, applied in the direction of using electric/magnetic devices to transfer sensing components, electromagnetic measuring devices, measuring devices, etc., can solve problems such as inability to obtain current drive capability, cracking, and transistor size limitations

Inactive Publication Date: 2004-10-20
SEIKO EPSON CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, the conventional capacitive fingerprint sensor has a problem of cracking when a finger is pressed against the fingerprint sensor because it is formed on a single crystal silicon substrate.
In addition, since the fingerprint sensor must be formed in the size of the finger area (approximately 20mm x 20mm), if it is formed on a single crystal silicon substrate, it will be expensive.
In the prior art configuration, a capacitance detection circuit composed of sensor electrodes and transistors is arranged in a matrix shape, and the transistor is driven by the capacitance change of the capacitance formed between the sensor electrodes and the finger, and a current flows to an external circuit. , since the size of the transistors configured in the fingerprint detection section is limited, there are problems such as the inability to obtain sufficient current drive capability and the inability to perform precise sensing

Method used

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  • Capacitor detecting device and its driving method, fingerprint sensor and biological identification device
  • Capacitor detecting device and its driving method, fingerprint sensor and biological identification device
  • Capacitor detecting device and its driving method, fingerprint sensor and biological identification device

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Experimental program
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Effect test

no. 1 approach

[0035] figure 2 It is a circuit configuration diagram of the electrostatic capacitance detection circuit 31 that converts the unevenness information of the subject's fingerprint into an electrical signal. The detection circuit 31 is configured to include: a selection transistor 32 for selecting the detection circuit 31; an electrostatic capacitance 33 formed between the subject’s finger and the sensor electrode; and a signal output element 34 for a small amount based on the electrostatic capacitance 33 Capacitor to output the detection information with fingerprint concave and convex information; scan line 36 to transmit the signal for switching control of the selection transistor 32; data line 37 to transmit the detection signal; low-potential power supply to form the output path of the detection signal Line Vss; and a reference capacitance Cs with a constant capacitance value. If the capacitance value of the electrostatic capacitance 33 is Cd, the detection capacitance Cd is ba...

Embodiment approach 2

[0050] Figure 7 It is a circuit configuration diagram of the electrostatic capacitance detection circuit 31 of the second embodiment of the present invention. The detection circuit 31 is configured to include the selection transistor 32, the electrostatic capacitor 33, the signal output element 34, the scan line 36, the data line 37, the reference capacitor Cs, and the low-potential power supply line Vss, and the reset transistor 38. The electrostatic capacitance detection circuit 31 shown in the figure is the same as the above-mentioned first embodiment. It is arranged in an array on the active matrix section 30, and the detection of the electrostatic capacitance 33 is read through the control of the data line driver 10 and the scan line driver 20. Capacity Cd. The reset transistor 38 is switched and controlled to be turned on during the stage (presensing time) of selecting the previous-stage electrostatic capacitance detection circuit 31.

[0051] Since the reset transistor 38...

Embodiment approach 3

[0054] Picture 9 It is a circuit configuration diagram of the electrostatic capacitance detection circuit 31 of the third embodiment of the present invention. The detection circuit 31 is configured to include the selection transistor 32, the electrostatic capacitor 33, the signal output element 34, the scanning line 36, the data line 37, the reference capacitor Cs, and the low-potential power supply line Vss, as well as the data line selection transistor 35, Line 50 is selected on the data side. The electrostatic capacitance detection circuit 31 shown in the figure is the same as the above-mentioned first embodiment. It is arranged in the active matrix section 30 in M ​​rows×N columns, and is read by the control of the data line driver 10 and the scan line driver 20. The detection capacity Cd of the electrostatic capacitor 33.

[0055] Focus on a specific data line 37. Since the detection signals from the M electrostatic capacitance detection circuits 31 arranged in the column d...

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Abstract

The object of the present invention is to provide a high-precision fingerprint sensor. In order to achieve this object, the fingerprint sensor of the present invention comprises a matrix portion in which capacitance detection circuits, which each output a detection signal corresponding to the capacitance formed between the capacitance detection circuit and a fingerprint, are arranged in the form of a matrix; and an amplification circuit for amplifying this detection signal. The amplification circuit functions as a signal source for outputting a detection signal to the capacitance detection circuit and is constituted such that the detection signal is transmitted from the amplification circuit to the low potential source line via the capacitance detection circuit.

Description

Technical field [0001] The present invention relates to an electrostatic capacitance detection technology, which reads the surface shape of an object to be inspected with minute irregularities such as fingerprints in an electrostatic capacitance change method. Background technique [0002] In Japanese Patent Laid-Open No. 11-118415, 2000-346608, 2001-56204, and 2001-133213, a fingerprint recognition technology is disclosed in which a single crystal silicon substrate is formed The sensor electrode surface of the sensor is covered with a sensing film, and the finger potential is used as a reference potential. The electrostatic capacitance formed between the finger and the sensor electrode changes according to the unevenness of the fingerprint to recognize the fingerprint. [0003] However, since the conventional electrostatic capacitive fingerprint sensor is formed on a single crystal silicon substrate, there is a problem that the fingerprint sensor is broken when the finger is pre...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01B7/28A61B5/117G01D5/24G06K9/00
CPCG01D5/24G06K9/0002G01D5/2405G06V40/1306G01B7/28A61B5/117
Inventor 原弘幸
Owner SEIKO EPSON CORP
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