JP2001099611A - Surface shape input device and individual identifying device using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain stable surface shape data by bringing the surface shape of a finger into contact with a sensor surface always in a stable state. SOLUTION: A sensor surface is formed by arranging sensor element electrodes 15 and curved to certain curvature in the array direction of the respective sensor elements, and a finger is brought into contact with the sensor surface so that its length is in the array direction of the respective sensor elements, thereby detecting the surface shape of the finger from variation in the impedance between the respective sensor elements and finger.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a surface shape input device for detecting the surface shape of a finger and a personal identification device using the same.

[0002]

2. Description of the Related Art As a surface shape input device used for a personal identification device, for example, a device described in Japanese Patent Application Laid-Open No. 7-168930 is known. This is because, as shown in FIG.
Are provided in a one-dimensional array, an electrode extraction pad 3 is connected to each electrode 2, and the longitudinal direction of the finger 4 is brought into contact with the direction in which the electrodes 2 are arranged. As shown in FIG. 10, a plurality of linear contact electrodes 2 are provided in a one-dimensional array on the outer peripheral surface of the substrate 5 formed in a curved shape.
The finger 4 is brought into contact with each linear contact electrode 2 along the longitudinal direction of the finger 4 along the convex surface.

When the finger 4 is brought into contact with each linear contact electrode 2, the resistance between adjacent linear contact electrodes 2 changes according to the amount of the convex portion of the fingerprint. Distribution or results. Therefore, a reference resistor and a constant voltage source are connected between two adjacent linear contact electrodes via an analog switch, and the analog switch is switched to read the potential difference between both ends of the reference resistor in the longitudinal direction of the finger. By plotting the resistance value calculated from the potential difference in a time-series manner, as shown in FIG. 11, one-dimensional fingerprint information represented by a resistance value equivalent to a multilevel projection signal in the longitudinal direction of the finger is obtained. It has become.

A personal identification device using this surface shape input device is, for example, a device that detects a fingerprint as a two-dimensional image signal or a device that converts a two-dimensional image signal into a one-dimensional signal and performs signal processing. Thus, the amount of data can be reduced by handling one-dimensional data, and the processing algorithm can be simplified and speeded up by directly obtaining one-dimensional data.

[0005]

By the way, the skin forming the surface of a person is usually slack to some extent, and naturally the skin on the ventral side of the finger is also slack to some extent. In order to reduce this sagging, it is necessary to extend the finger fully, and when the finger is fully extended, the entire finger is warped to the back side of the hand, even if there are some individual differences.

However, in the above-described conventional surface shape input device, the sensor surface on which the plurality of linear contact electrodes are arranged is a flat surface or a convex surface. When the finger is stretched, the skin on the abdomen does not sag and the skin on the abdomen sags. This means that the belly side of the finger is deformed due to the contact state, and therefore, the surface shape of the finger changes due to a slight difference in how the finger is placed on the sensor surface, and the same person touches the same finger on the sensor surface. Even when the contact is made, the data of the surface shape output each time the contact is made changes, and as a result, there is a problem that the personal acceptance rate decreases in personal identification and the identification accuracy deteriorates.

In view of the above, the first aspect of the present invention provides a surface shape input device capable of constantly bringing the surface shape of a finger into contact with the sensor surface in a stable state and obtaining stable surface shape data.

[0008] The invention according to claim 2 provides a personal identification device that can perform individual identification using stable surface shape data, and can increase the personal acceptance rate and improve the identification accuracy.

[0009]

According to the first aspect of the present invention,
A sensor surface is formed by arranging a plurality of sensor elements in one direction,
This sensor surface is a concave surface having a constant curvature in the direction in which the sensor elements are arranged, and the longitudinal direction of the finger is brought into contact with the sensor surface in accordance with the direction in which the sensor elements are arranged. The surface shape input device detects the surface shape of the finger from a change in the electrical characteristics between the finger and the surface.

According to a second aspect of the present invention, a plurality of sensor elements are arranged in one direction to form a sensor surface, and the sensor surface is formed as a concave surface having a constant curvature in the direction in which the sensor elements are arranged. A surface shape input device for contacting the surface with the longitudinal direction of the finger in accordance with the direction in which the sensor elements are arranged, and detecting the surface shape of the finger from a change in electrical characteristics between each sensor element and the finger; An information processing unit for performing personal identification based on surface shape detection information from a shape input device.

[0011]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a personal identification device, 11 is a surface shape input device for detecting the surface shape of a finger, and 12 is information for performing personal identification based on surface shape detection information from the surface shape input device 11. It is a processing unit.

The surface shape input device 11 includes an input unit 13 having a sensor surface for contacting a finger.
3 is a flexible pattern in which a plurality of sensor element electrodes 15 and one common electrode 16 are patterned at a predetermined interval on a concave surface of a base 14 which is curved at a constant curvature in one direction, as shown in FIGS. A flexible substrate 17 formed by laminating a plate and another flexible plate is attached. The radius of curvature of the concave surface of the base 13 is preferably about 250 mm to 500 mm.
50mm. As the flexible substrate 17, any material may be used as long as it is a flexible and insulating material such as a polyimide film or a PET film.

Each of the sensor element electrodes 15 has a length of 20.
mm and 100μm wide electrode, which is 200μ in one direction
256 lines are arranged at m pitch, and the total length L is 5
A sensor surface 18 having a width of 1.1 mm and a width W of 20 mm is formed. Further, each of the sensor element electrodes 15 and the common electrode 16
The distance between the surface of the flexible substrate 17 and the surface of the flexible substrate 17 is about 12 μm.

In order to detect the surface shape of the abdomen of the finger 19, the longitudinal direction of the finger 19 is set to the above-mentioned sensor element electrode 1
The abdomen is brought into contact with the surface of the flexible substrate 17 so that the common electrode 16 is located near the base of the finger 19 at that time in accordance with the direction in which the fingers 5 are arranged.

As shown in FIG. 4, the surface shape input device 11 connects a switch element 20 to each sensor element electrode 15 and connects each switch element 20 to a detection circuit 21.
Are sequentially turned on by the control circuit 22 described above, and a carrier signal having a frequency of, for example, 2 MHz is sequentially supplied from the oscillator 23 to each of the sensor element electrodes 15.

That is, as shown in FIG.
, And the switch elements 20 are sequentially turned on by the switch selection signals SEL1 to SEL256. For example, as shown in FIG. 7, the switching elements 20 are turned on by the i-th switch selection signal SELi. The carrier signal CARRIER is supplied to the i-th sensor element electrode 15 for a fixed time.

While a finger 19 is in contact with the surface of the input section 13, a carrier signal is sequentially applied to each of the sensor element electrodes 15.
By supplying CARRIER, this carrier signal is
And sequentially reaches the common electrode 16. In the process, the amplitude is attenuated by electric characteristics between each sensor element electrode 15 and the common electrode 16, for example, impedance.

Since the surface of the abdomen of the finger 19 has irregularities due to wrinkles or the like, the size of the gap between the finger 19 and each sensor element electrode 15 differs depending on the position, that is, each sensor element electrode. Therefore, the impedance between each sensor element electrode 15 and the common electrode 16 also differs individually. For this reason, there is a difference in the amount of attenuation until the carrier signal input to each sensor element electrode 15 reaches the common electrode 16 according to the size of the gap between the finger 19 and each sensor element electrode 15. That is, a difference occurs in the amplitude. In particular, since the air gap is large at the finger joint, the impedance also increases, and the attenuation of the carrier signal increases.

As shown in FIG. 5, the carrier signal reaching the common electrode 16 is amplified by an amplifier 24 of a detection circuit 21 and then detected by a detection circuit 25 to remove the carrier component of the carrier signal. The signal is converted into a digital signal by the D converter 26. Then, the digital signal is transmitted to the information processing section 12 via the I / F (interface) circuit 27 as finger surface shape data.

The control circuit 22 controls the switching of each switch element 20 and also controls the operation timing of the A / D converter 26 and the I / F circuit 27.

As shown in FIG. 8, the information processing apparatus 12 includes a band-pass filter 28, a storage unit 29, and a comparison / judgment unit 30, and converts the surface shape data from the I / F circuit 27 of the detection circuit 21. By passing through the band-pass filter 28, noise is removed and features are extracted, and the surface shape data after passing through the filter is stored in the storage unit 29. The storage of the surface shape data in the storage unit 29 is for registering data for each individual in advance, and this data is used as data for comparison at the time of individual identification.

At the time of personal identification, the comparison / judgment unit 30 compares the surface shape data from the hand-pass filter 28 with the surface shape data of each individual registered in the storage unit 29, and makes a judgment. And outputs the result to the outside.

The comparison and judgment of the data by the comparison / judgment unit 30 is the same based on the calculated value obtained by calculating the difference between the detected surface shape data and the surface shape data registered in the storage unit 29. Is determined.

When a personal computer is used as the information processing unit 12, for example, it is possible to restrict the use of application software, restrict access to files, and the like without using a password. Also, access control of other devices can be performed through a personal computer.

Furthermore, the information processing section 12 can be integrated into an IC and integrated with the surface shape input device. In this way, it is possible to directly connect to various devices, and similarly, it is possible to perform access control and use restriction of devices for maintaining confidentiality.

In such a configuration, when the abdomen of the finger 19 is brought into contact with the surface of the input section 13, the surface of the input section 13 is a concave surface having a constant curvature. The finger 19 warps, and the skin on the abdomen of the finger 19 becomes stretched. Accordingly, the abdominal shape of the finger 19 has no allowance for deformation, and the surface shape of the finger is stabilized.

As described above, by making the surface of the input section 13 of the surface shape input device 11 a concave surface having a constant curvature, the surface shape of the finger 19 contacting the sensor surface 18 can be always stabilized. .

In this state, when the switching element 20 is selectively switched to sequentially supply the carrier signal from the oscillator 23 to each sensor element electrode 15 sequentially, the carrier passing from the common electrode 16 through the finger 19 is supplied. A signal is obtained, and the carrier signal is amplified by the amplifier 24 of the detection circuit 21, detected by the detection circuit 25 to remove the carrier component, and further converted by the A / D converter 26 into a digital signal. Thus, the surface shape data of the finger is transmitted to the information processing section 12 via the I / F circuit 27.

As described above, since the surface shape of the finger 19 to be brought into contact with the sensor surface 18 can be always stabilized, the surface shape data of the finger transmitted to the information processing section 12 is stable.

At the time of registration, the information processing unit 1
In step 2, the surface shape data is registered in the storage unit 29 via the band pass filter 28. In this way, the surface shape data of a plurality of human fingers can be registered in the storage unit 29.

At the time of personal identification, the information processing unit 12 supplies the surface shape data of the finger 19 from the surface shape input device 11 to the comparison / judgment unit 30 via the band pass filter 28. The comparison / judgment unit 30 compares the acquired surface shape data with the surface shape data of each individual registered in the storage unit 29 and performs collation. This calculates an error between the two surface shape data to be compared, and if the error is equal to or less than a predetermined value, it is determined that the user is the person.

As described above, the surface shape of the finger 19 contacting the sensor surface 18 of the input unit 13 can be constantly stabilized, and the surface shape data of the finger transmitted to the information processing unit 12 can be made stable data. The surface shape data of the finger detected by the same person at the time of registration and the surface shape data of the finger detected at the time of subsequent personal identification can be made to substantially coincide with each other, so that the individual acceptance rate can be increased and the identification accuracy can be improved.

The radius of curvature of the concave surface of the base 13, that is, the radius of curvature of the input section 13 is set to 250 mm to 500 mm.
The reason is that if it exceeds 500 mm, there is no difference in effect compared to the case where the surface is flat, and 250 mm
If it is less than 3, the curvature becomes large, and it is difficult to bring the entire finger 19 into contact with the sensor surface. Therefore, the contact of the finger 19 varies, and stable surface shape data cannot be obtained.

In this embodiment, a change in impedance when a carrier signal from an oscillator is passed is detected as a change in electrical characteristics between each sensor element electrode and the finger. Although the surface shape is detected, the present invention is not limited to this. The point is that a change in electrical characteristics caused by contact with a finger is detected, and the surface shape of the finger is detected from the change in electrical characteristics.

[0035]

According to the first aspect of the present invention, there is provided a surface shape input device capable of making the surface shape of the finger always contact the sensor surface in a stable state, and obtaining stable surface shape data. it can. According to the second aspect of the present invention, it is possible to provide a personal identification device capable of performing individual identification using stable surface shape data, increasing a personal acceptance rate and improving identification accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram of a personal identification device showing an embodiment of the present invention.

FIG. 2 is a partially stepped view showing a configuration of an input unit of the surface shape input device according to the embodiment.

FIG. 3 is a plan view showing a configuration of an input unit of the surface shape input device according to the embodiment.

FIG. 4 is a block diagram showing a configuration of the surface shape input device according to the embodiment;

FIG. 5 is a block diagram showing a configuration of a detection circuit of the surface shape input device according to the embodiment.

FIG. 6 is a diagram showing a relationship between a carrier signal and operation timing of each switching element in the embodiment.

FIG. 7 is a diagram showing a carrier signal, an operation of one switching element, and a carrier signal supplied to a sensor element electrode in the embodiment.

FIG. 8 is a block diagram showing a configuration of an information processing unit according to the embodiment.

FIG. 9 is a diagram showing an example of a conventional surface shape input device.

FIG. 10 is a diagram showing another example of a conventional surface shape input device.

FIG. 11 is a diagram showing an example of a signal waveform obtained by a conventional surface shape input device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Surface shape input device 12 ... Information processing part 13 ... Input part 15 ... Sensor element electrode 16 ... Common electrode 18 ... Sensor surface 19 ... Finger

Claims (2)

[Claims] A sensor surface is formed by arranging a plurality of sensor elements in one direction. The sensor surface is a concave surface having a constant curvature in the direction in which the sensor elements are arranged. A surface shape input device characterized in that the direction of the finger is brought into contact with the direction in which the sensor elements are arranged, and the surface shape of the finger is detected by a change in electrical characteristics between the sensor element and the finger. 2. A sensor surface is formed by arranging a plurality of sensor elements in one direction. The sensor surface is a concave surface having a constant curvature in the direction in which the sensor elements are arranged. A surface shape input device for detecting the surface shape of a finger from a change in electrical characteristics between each sensor element and a finger, by contacting the direction in accordance with the direction in which the respective sensor elements are arranged,
An information processing unit for performing personal identification based on surface shape detection information from the surface shape input device.