JPH02146691A - Fingerprint picture input device - Google Patents

Abstract

PURPOSE:To widen a detection area and to eliminate graphic distortion by fixing a one-dimensional image sensor and an illuminating means so that they can satisfy total reflection conditions for the inner surface of glass and executing scanning while the conditions are kept as they are. CONSTITUTION:Transparent glass 11, for which its inner and outer surfaces are bent so that they can be a concentric cylinders, is made into a base on which a finger FNG is mounted, an illuminator 13 to uniformly illuminate a one-dimensional image sensor 12 equipped with an optical fiber lens 16 and an image pickup range for the image sensor 12 is provided, and the image sensor 12 and the illuminator 13 are fixed so that they can have a positional relation to satisfy the total reflection conditions in the inner surface of the bent transparent glass 11. Further, the image sensor 12 and the illuminator 13 are fixed on the same supporting base 15, this supporting base 15 is fixed to the rotary shaft of a pulse motor 14, and this rotary shaft of the pulse motor 14 is set identically to the center axis of the bent transparent glass 11. Thus, a fingerprint picture having the wide detection area and no graphic distortion can be obtained by detecting the fingerprint picture of the finger pressed on the surface of the bent glass surface 11.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a fingerprint image input device, and more particularly to a device for inputting a fingerprint image directly from a finger without using ink.

Prior Art Conventionally, in this type of apparatus, a method as shown in FIG. 2 has been used. 20 is a right angle prism, and lamp 2
1 is illuminated from one side.

The light from the lamp 21 is totally reflected by the surface A-A' of the right-angle prism 20 and is input to the TV right camera 2. On the surface A-A' of the rectangular prism 20, as shown in FIG. 3, in the area where the skin is in contact with the prism, the conditions for total reflection are disrupted due to the slight amount of sweat secreted from the skin, resulting in diffuse reflection. There is total reflection in areas where there is no light. Therefore, the TV right camera 2 can detect the difference in the amount of reflected light between the ridges and valleys of the fingerprint as a fingerprint image.

The fingerprint image signal (analog signal) output from the TV right camera 2 is quantized by the A/D conversion circuit 23 and input to the storage circuit 24 for storage. The start of A/D conversion and writing to the memory circuit 24 are performed by the operator or the monitor 25.
The user judges the image quality while looking at the image and instructs the user to start inputting from the keyboard 26. When there is an instruction to start input from the keyboard 26, the A/D conversion clock and signals necessary for writing image data into the storage circuit 24 are outputted from the control circuit F1+21, and the fingerprint image data is stored in the storage circuit 24.

Further, the fingerprint image data stored in the storage circuit 24 is input to the postcomputer via the ink face 28.

Problems to be Solved by the Invention As described above, since the conventional device uses a right-angled prism, it is a flat surface on which a finger, which is an input object, is placed. Therefore, since the area where the finger touches the prism is small, there is a drawback that only a fingerprint image of a small portion of the finger can be input. Furthermore, since the image is taken from an oblique angle with a TV camera, the detected fingerprint image is obtained without trapezoidal distortion.

The present invention has been made in view of the above-mentioned drawbacks of the conventional technology, and therefore, it is an object of the present invention to solve the above-mentioned drawbacks inherent in the conventional technology, and to provide a high-quality product with a wide detection area and no graphic distortion. An object of the present invention is to provide a novel fingerprint image input device that makes it possible to obtain a fingerprint image.

Means for Solving the Problems In order to achieve the above object, the fingerprint image input device according to the present invention includes a transparent glass whose inner and outer surfaces are curved into concentric cylinders, and an inner surface of the transparent glass. A one-dimensional image sensor including an imaging system fixed to be in focus, an illumination means for uniformly illuminating a linear imaging area of the one-dimensional image sensor, the one-dimensional image sensor and the illumination means. is fixed to the inner surface of the glass so as to satisfy the total reflection condition, and while maintaining that condition, the sub-scanning of the one-dimensional image sensor is performed along the outer periphery of the glass beyond the originally required imaging range. and a control means for controlling.

Embodiment Next, a preferred embodiment of the present invention will be specifically explained with reference to the drawings.

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

Referring to FIG. 1, reference number 1 is a fingerprint detection unit;
The details are shown in FIG.

In FIG. 4, reference numeral 11 is a transparent glass whose inner and outer surfaces are curved to form concentric cylinders, and serves as a stand on which the finger FNG is placed. 12 is a one-dimensional image sensor equipped with optical fiber lenses 16 arranged one-dimensionally. 1
3 is an illuminator that uniformly illuminates the imaging range of the image sensor 12. The image sensor 12 and illuminator 13 are
As shown in FIG. 5, it is fixed in a positional relationship that satisfies the total reflection condition on the inner surface of the curved transparent glass 11. This image sensor 12 detects and outputs an image of the inner surface of the curved transparent glass 11 using an optical fiber lens 16. The image sensor 12 and the illuminator 13 are fixed on the same indicator 15.

Further, the indicator 5 is fixed to the rotating shaft of a pulse motor 14, and the rotating shaft of the pulse motor 14 is set to be the same as the central axis of the curved transparent glass 11.
When rotated by a drive pulse from the pulse motor 14 or the control circuit 5, the image sensor 12 and the illuminator 13 move around the outer periphery of the curved transparent glass 11 while maintaining total reflection conditions against the inner surface of the curved transparent glass 11.

Here, the sub-scanning of the image sensor 12 will be described in more detail using FIGS. 6(a) and 6(b). It is assumed that the image sensor 12 images the zero point before the start of sub-scanning. #I# The pulse motor 14 starts reverse rotation according to the drive pulse signal from the circuit 5, returns to the 0 point, changes to normal rotation from that point, scans to the 0 point, changes to reverse rotation again, returns to ①, and stops. Normally, the left end is the 0 point, which is also the left end of the imaging area, and it seems okay to rotate forward, or as shown in Figure 6 (b), the points at ■, ■, ■, and ■ where the acceleration changes. Since mechanical vibrations (damped vibrations) occur, if the rotation is returned to normal at the 0 point, the image will be at the beginning of the imaging area or exactly at the vibrating area, making it impossible to obtain a correct image.

Therefore, after slightly overscanning and moving to the 0 point, the rotation is returned to normal rotation and data input is performed.

The output signal from the image sensor 12 driven by the clock signal from the control circuit 5 is input to the A/D conversion circuit 2 and quantized, and the output signal is input to the storage circuit 3 and stored. Furthermore, the image take stored in the storage circuit 3 is sent to a host computer (not shown) via an interface circuit 4.

As described in detail, the present invention makes it possible to detect a fingerprint image of a finger pressed on a curved glass surface, thereby making it possible to obtain a fingerprint image with a large detection area and no shape distortion. It's effective.

Furthermore, according to the present invention, in sub-scanning which is mechanical scanning, image data is input while avoiding mechanical vibration parts that occur in parts where acceleration changes.
This has the effect of providing a high quality fingerprint image.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG.
The figure is a block diagram of a fingerprint image input device using a conventional prism, and Figure 3 is a diagram showing the principle of fingerprint image detection using total internal reflection.
FIG. 4 is a schematic configuration diagram showing details of the fingerprint detection section included in FIG.
) and (b) are diagrams for explaining sub-scanning of the image sensor 12 in detail. DESCRIPTION OF SYMBOLS 1... Fingerprint detection unit, 2... A/D conversion circuit, 3... Memory circuit, 4 - Interface circuit, 5... Control circuit, 11... Curved transparent glass, 12... One-dimensional image sensor , 13... Illuminator, 14... Pulse motor, 15
Support stand for image sensor and illuminator, 16...Fiber optic lens, FNG...Finger Patent applicant: NEC Corporation Agent

Claims (1)

[Claims] A one-dimensional image sensor comprising a transparent glass whose inner and outer surfaces are curved to form concentric cylinders, an imaging system fixed to focus on the inner surface of the transparent glass, and this one-dimensional image sensor. an illumination means for uniformly illuminating a linear imaging area; and the one-dimensional image sensor and the illumination means are fixed to the inner surface of the glass so as to satisfy a total reflection condition, and the condition is maintained. A fingerprint image input device comprising means for controlling sub-scanning of the one-dimensional image sensor along the outer periphery of the glass so that it scans over an originally required imaging range.