JPH10198784A - Device for optically reading fingerprint or the like - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a miniaturized device for optically reading fingerprint or the like, and to facilitate the work such as the maintenance/exchange of camera, etc. SOLUTION: This device is provided with a prism 2, a light source 8, a CCD camera 5, a 1st mirror 3 for receiving 2nd-order light B2 emitted from a light emitting plane 2c of the prism, and a 2nd mirror 4 for receiving 3rd-order light B3 reflected from the 1st mirror 3 and forming 4th-order light B4 toward the camera 5. The reflecting plane of the 1st mirror 3 is inclined so that the 3rd-order light B3 can be almost vertical rather than the 2nd-order light B2. The reflecting plane of the 2nd mirror 4 is inclined so that the 4th-order light B4 can be almost horizontal rather than the 3rd-order light B3. Besides, a holding substrate 1 to be arranged horizontally is provided. The prism 2 is fixed on the holding substrate 1 so that the upper surface of holding substrate 1 and an objective plane 2 of the prism 2 can be almost communicated. A holding panel 6 is provided for holding the camera 5, the 1st mirror 3 and the 2nd mirror 4. The apex part of the holding panel 6 is fixed on the holding substrate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small optical fingerprint reader for reading fingerprints and palm prints.

[0002]

2. Description of the Related Art When an object to be imaged is widened, the angle of view of the camera becomes large, and the imaging distance (optical path length) naturally becomes large.
Such optical fingerprint readers are large and fixed. A device that can read a palm print exceeding the size of a fingerprint is large, and it is difficult to carry it with a hand.
Therefore, a portable device that can read a palm print is desired. In addition, it takes time to adjust the optical axis and focus of the camera at the time of maintenance / replacement of the camera. However, such an operation is easy and a portable small device is desired.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to propose a miniaturized structure of an optical fingerprint reader or the like. Another object of the present invention is to provide a portable device capable of reading palm prints. Another object of the present invention is to facilitate maintenance and replacement of a camera or the like.

[0004]

SUMMARY OF THE INVENTION An optical fingerprint reader or the like according to the present invention includes a prism having three surfaces, an object surface, a light incident surface, and a light exit surface, and arranged so that the object surface is horizontal.
A light source disposed near the light incident surface for projecting light from the light incident surface toward the object surface to illuminate a finger or the like pressed against the object surface; A camera of a two-dimensional charge-coupled device type for imaging the finger or the like pressed against the object plane; A first mirror for receiving secondary light from the light exit surface. A second mirror that receives tertiary light reflected from the first mirror and forms quaternary light toward the camera. The reflecting surface of the first mirror is inclined such that the tertiary light is closer to the vertical than the secondary light, and the reflecting surface of the second mirror is more horizontal in the quaternary light than in the tertiary light. Tilt so that it is close to When the first mirror and the second mirror are arranged as described above, a required imaging distance (optical path length) can be ensured, and the size of the apparatus can be reduced. In addition, a support substrate that is disposed horizontally is provided. A prism is fixed to the support substrate such that the upper surface of the support substrate and the objective surface of the prism are substantially connected. A holding plate for holding the camera, the first mirror, and the second mirror is provided. The top of the holding plate is fixed to the support substrate. With this configuration, the dimensional accuracy of the optical system is ensured, and maintenance and maintenance of the camera unit including the camera
Exchange is easy.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention are shown in FIGS.
This will be described with reference to FIG. As shown in the above figures, particularly FIGS. 1 to 4, the optical fingerprint reader or the like shown in FIG.
It has a prism 2 having three surfaces of a light entrance surface 2b and a light exit surface 2c and arranged so that the objective surface 2a is horizontal. A light source 8 is disposed near the light incident surface 2b and projects light B1 from the light incident surface 2b toward the object surface 2a to illuminate a finger 14 pressed against the object surface 2a. A two-dimensional charge-coupled device (C) for imaging the finger or the like 14 pressed against the object surface 2a
It has a camera 5 of the CD) type. L and H in FIG. 4 are the horizontal and height dimensions of the main part (optical system part) of the apparatus. The present invention contemplates this range compactly and intends to reduce the size of the entire device. Examples of realization as a real machine include a width of 300 mm, a height of 180 mm, and a depth of 490 mm. This number is
Although it originally has a width, it is important for understanding miniaturization. The first mirror 3 is provided for receiving the secondary light B2 emitted from the light exit surface 2c. A second mirror that receives the tertiary light B3 reflected from the first mirror 3 and forms a quaternary light B4 toward the camera 5; The tilt angle Φ of the camera 5 in FIG.
Coincides with the direction of the fourth-order light B4.

In the present invention, the reflecting surface of the first mirror 3 is inclined such that the tertiary light B3 is closer to the vertical than the secondary light B2. This inclination angle is θ1 in FIG. The reflecting surface of the second mirror 4 is inclined such that the quaternary light B4 is closer to the horizontal than the tertiary light B3. This inclination angle is θ2 in FIG. The terms “horizontal”, “vertical” and the like in this specification are based on the normal use posture of the optical fingerprint reader. Light entrance surface 2b / light exit surface 2c of prism 2 and objective surface 2a
The angle between them is 45 degrees. The tertiary light B3 is the reflected light of the first mirror 3 and the incident light of the second mirror 4. Fingers 14
Is a palm (palm). The objective surface 2a has a size on which the palm 14 rides. The light source 8 is a small surface light source. The illustrated optical fingerprint reader or the like includes a support substrate 1. The support substrate 1 is arranged horizontally, and the prism 2
Are fixed so that the upper surface of the support substrate 1 and the objective surface 2a of the prism 2 are substantially connected. The fixing structure of the prism 2 will be described with reference to FIGS. A concave groove 2d parallel to the object surface 2a is provided at a position near the object surface 2a in the prism 2. A U-shaped notch 1a having a shape substantially corresponding to the objective surface 2a is provided at an end of the support substrate 1. The edge 1b of the notch 1a is engaged with the groove 2d. The prism 2 is fixed in a state in which it contacts the inner side 1d of the notch 1a.

As shown in FIGS. 1 to 3, a camera 5, a first mirror 3, and a second mirror 4 are fixed to a support substrate 1 so that they are located below the support substrate 1. In particular,
A holding plate 6 for holding the camera 5, the first mirror 3, and the second mirror 4 is provided, and the top of the holding plate 6 is fixed to the support substrate 1. The holding plate 6 has a U-shaped cross section opened to the lower side, and includes a pair of right and left walls 6a and 6b facing each other.
The holding plate 6 forms a camera unit 7 together with the internal camera 5 and the like. The camera 5 is fixed to a camera base 9, and both ends of the camera base 9 are screwed to the right wall 6 a and the left wall 6.
fixed to b. A slide mechanism that allows the holding plate 6 to move horizontally with respect to the support substrate 1 is provided. The direction of the horizontal movement is a direction connecting the prism 2, the first mirror 3, the second mirror 4, and the camera 5. The slide mechanism will be described with reference to FIGS. 2, 3, 8, and 9. A pair of rail members 25
a and 25b are fixed to the lower surface on one side and the lower surface on the other side of the support substrate 1. 26a and 27 are stopper holes for that purpose. Holding plate 6
Cut-out projections 17a, 17b, 17 at the top four corners
Form c · 17d. The projections 17a to 17d are inserted into the edge grooves of the rail members 25a and 25b. With the camera unit 7 in the correct position, tighten the screw 24 to
-The holding plates 6 are firmly connected to each other. At this time, the dowels 19a and 19b of the holding plate 6 are
2 to increase the mutual positioning accuracy.

The structure for fixing the first mirror 3 to the holding plate 6 will be described with reference to FIGS. 2, 6, and 7. Holding plate 6
The openings 15a and 15b are provided in the right wall 6a and the left wall 6b of the first embodiment.
A pair of downward projections 1 divided into right and left at the upper edge of the opening 15a
5a1 and 15a2 are provided. A downward projection 15b1 is provided at the center of the upper edge of the opening 15b. Both ends of the first mirror 3 are inserted into the right wall 6a and the left wall 6b. Fixing fittings 28a and 28b are fixed near the openings 15a and 15b of the right wall 6a and the left wall 6b with screws 29a and 29b. Fixing fittings 28a / 28
b raises the first mirror 3. In this state, the first mirror 3 is pressed against the downward projections 15a1, 15a2, and 15b1, and is positioned with high accuracy. The fixing structure of the second mirror 4 is substantially the same. Openings 16a and 15b and upward projections 16a1 and 16a2 formed on their lower edges
And the like constitute a second mirror 4 fixing structure similar to the above. FIG.
3 and 4 denotes a housing, which includes a right side plate 31, a left side plate 32, a bottom plate 33, and the like, and forms an outer shell of the entire apparatus. The upper surface of the housing 12 has a window through which the objective surface 2 a can be exposed to the outside, and the other upper surface of the support substrate 1 is covered with the housing 12. Only the objective surface 2a is exposed to the outside. Reference numeral 10 in FIG. 1 denotes an image processing board arranged at a lower portion of the housing 12, which receives a digital signal transmitted from the camera 5 and performs image processing. The result is displayed on the attached monitor 11 (see FIG. 10). The data is stored in a storage unit (not shown) in the housing 12. Further, the data is appropriately transmitted to an external display device made of a liquid crystal or the like via an interface connector 13 facing the outer surface of the housing 12.

As shown in FIGS. 1 and 11, the palm 14
Of the prism 2 contacts the objective surface 2a of the prism 2. The light B1 arriving there is irregularly reflected there, and the diffused secondary light B2
To form Since the valley line 14b of the palm 14 does not contact the objective surface 2a of the prism 2, the light B1 is specularly reflected by the objective surface 2a, and forms a secondary light B2 having high directivity. When this difference is observed from the position of the camera 5 via the secondary light B2, the tertiary light B3, and the quaternary light B4, the ridges 14a appear dark and the valleys 14b appear bright. In image processing, the former is processed as black and the latter as white. The support substrate 1 is an important component for the positioning accuracy of the optical system. It is arranged at the top plate position of the housing 12. In other words, it is a top plate-shaped support substrate 1. Since it is the top plate-shaped support substrate 1, the prism 2 disposed at a high place of the apparatus can be directly and accurately fixed thereto. The structure in which the groove 2d cut in the prism 2 is directly engaged with the support substrate 1 is an inexpensive and highly accurate positioning means. The first mirror 3, the second mirror 4, and the camera 5 are fixed to a holding plate 6 to form a camera unit 7. Replacement of camera 5 etc. with camera unit 7
Perform in units of The replacement can be performed simply by attaching and detaching the camera unit 7 to and from the support substrate 1 at a time, so that it can be easily performed on site. The first mirror 3 and the second mirror 4 are added to the area of the unit 7 and the prism 2 is excluded.
The reason is that the second mirror 4 is inexpensive, but the prism 2 is expensive. The slide mechanism is an inexpensive and easy assembling means for the camera unit 7.

In FIG. 4, if the reflecting surface of the first mirror 3 is horizontal, the secondary light B2 and the tertiary light B3 are symmetrical with respect to a vertical line, but are actually inclined counterclockwise by θ1. If the reflecting surface of the second mirror 4 is horizontal, the tertiary light B3 and the quaternary light B4 are symmetric with respect to the horizontal line, but are actually inclined counterclockwise by θ2. The respective reflecting surfaces of the first mirror 3 and the second mirror 4 are both counterclockwise inclined, but the former reflecting surface is upward and the latter reflecting surface is downward. For this reason, the reflection by the former makes the reflected light (tertiary light B3) closer to vertical,
The reflection by the latter tends to make the reflected light (fourth order light B4) closer to horizontal. The inclination of each of the reflecting surfaces of the first mirror 3 and the second mirror 4 will be additionally described with reference to FIG. FIG.
2 (a) has the same settings as in FIG.
Both the second mirrors 4 are tilted counterclockwise. Both the first mirror 3 and the second mirror 4 in (b) tilt clockwise. (C)
The first mirror 3 tilts clockwise and the second mirror 4 tilts counterclockwise. (A) is compatible with the present invention, and (b) and (c) are not compatible with the present invention. In the case of (a), the entire apparatus is compact, but in the cases of (b) and (c), the horizontal dimension or the height dimension of the entire apparatus is large. The reasons are as follows.

FIG. 12 in which the inclination of the first mirror 3 is counterclockwise.
In the case of (a), the horizontal distance between the prism 2 and the second mirror 4 is small, and in the case of clockwise (b) and (c), the horizontal distance is large. In any case, the optical path length from the prism 2 to the second mirror 4 hardly changes. The limit of the counterclockwise tilt of the first mirror 3 is at the level shown in FIG. 12A, and when exceeding the limit, the second mirror 4 blocks a part of the secondary light B2. In the case of FIG. 12A, the tertiary light B3, which is approximately vertical, is received by the second mirror 4 inclined counterclockwise to form the quaternary light B4, which is approximately horizontal. In the case (a), the height difference between the prism 2 and the camera 5 is small. In the case of (b), the tertiary light B3 approximated horizontally is received by the second mirror 4 inclined clockwise, and the quaternary light B4 approximated vertically is formed. In the case of (b), even if the optical path of the fourth-order light B4 is shortened, the height difference between the prism 2 and the camera 5 becomes large. In the case of (c), the tertiary light B3, which is approximately horizontal, is received by the second mirror 4 inclined counterclockwise to form the quaternary light B4, which is approximately horizontal. In the case of (c), the angle of incidence and the angle of reflection of the second mirror 4 are excessively large, narrowing the field of view and causing image distortion. To avoid it, the height difference between the prism 2 and the camera 5 increases. .

[0012]

Since the first mirror and the second mirror interposed between the prism and the camera of the present invention are arranged so as to have a required inclination, a small optical fingerprint reader or the like can be obtained. In addition, since the top plate-shaped mounting substrate is used and the prism and the like are fixed thereto, the positioning accuracy of the optical system can be improved. Furthermore, since each mirror and camera are unitized and fixed to the support substrate, maintenance and maintenance of the camera etc.
Exchange is easy.

[Brief description of the drawings]

FIG. 1 is a front sectional view of an optical fingerprint reader or the like according to the present invention.

FIG. 2 is an exploded perspective view of a main part of the apparatus.

FIG. 3 is a left side view excluding a part of a housing of the apparatus.

FIG. 4 is a schematic front sectional view showing an optical system of the apparatus.

FIG. 5 is a left side view showing a prism of the device.

FIG. 6 is a left side view of a main part showing the vicinity of a first mirror of the device.

FIG. 7 is a partially cutaway enlarged view showing the vicinity of a first mirror of the device.

FIG. 8 is a left side view of a main part showing the vicinity of a slide mechanism of the apparatus.

FIG. 9 is a left side view of a main part showing a state after fixation similar to FIG. 8;

FIG. 10 is an explanatory diagram showing an imaging / processing procedure of the apparatus.

11 is an enlarged explanatory view of a main part showing the vicinity of the object plane in FIG. 1;

FIG. 12 is an explanatory diagram illustrating inclination of a first mirror and the like.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Support substrate 1a Notch 1b Edge 1d Back side 2 Prism 2a Object surface 2b Light entrance surface 2c Light exit surface 2d Concave groove 3 First mirror 4 Second mirror 5 Camera 6 Holding plate 6a Right wall 6b Left wall 7 Camera unit 8 Light source 9 Camera base 10 Image processing board 11 Monitor 12 Housing 13 Interface connector 14 Finger 14a Ridge 14b Valley 15a, 15b, 16a Opening 15a1, 15a2, 15b1 Downward projection 16a1, 16a2 Upward projection 17a, 17b, 17c, 17d Projection 18, 24, 29a, 29b Screw 19a, 19b Push dowel 21 hole 22 Long hole 25a, 25b Rail member 26a, 27 Stop hole 28a, 28b Fixing bracket 31, 32 Left side plate 33 Bottom plate B1 light B2 Secondary light B3 Tertiary light B4 Quaternary light θ1, θ2 tilt angle Φ tilt angle

Claims (5)

[Claims] 1. A prism having three surfaces of an object surface, a light incident surface, and a light exit surface, the prism being arranged so that the object surface is horizontal, and a prism arranged near the light incident surface and from the light incident surface to the object. A light source for projecting light toward a surface to illuminate a finger or the like pressed against the object surface, and a camera for imaging the finger or the like pressed to the object surface; A first mirror for receiving secondary light emitted from a surface, and a second mirror for receiving tertiary light reflected from the first mirror and forming quaternary light toward the camera, and reflecting the first mirror. The surface is inclined such that the tertiary light is closer to the vertical than the secondary light, and the reflecting surface of the second mirror is inclined such that the quaternary light is closer to the horizontal than the tertiary light. Optical fingerprint reader, etc. 2. The optical fingerprint reader according to claim 1, further comprising a support substrate disposed horizontally, wherein a prism is provided on the support substrate such that an upper surface of the support substrate and an objective surface of the prism are substantially connected. Fix the camera and camera
An optical fingerprint reading device in which a first mirror and a second mirror are fixed so as to be located below the supporting substrate. 3. The optical fingerprint reading apparatus according to claim 2, wherein a concave groove parallel to the objective surface is provided at a position near the objective surface of the prism, and the support substrate is cut into a shape substantially corresponding to the objective surface. An optical fingerprint reader or the like in which a notch is provided and an edge of the notch is engaged with the concave groove. 4. The optical fingerprint reading apparatus according to claim 1, further comprising a support substrate disposed horizontally, wherein a prism is provided on the support substrate such that an upper surface of the support substrate and an objective surface of the prism are substantially connected. An optical fingerprint reader or the like, comprising: a holding plate fixed to hold a camera, a first mirror, and a second mirror, and a top of the holding plate is fixed to the support substrate. 5. The optical fingerprint reading device according to claim 4, further comprising a slide mechanism for allowing the holding plate to move horizontally with respect to the support substrate, wherein the direction of the horizontal movement is determined by a prism.
An optical fingerprint reader that connects the first mirror, second mirror, and camera.