JP2711191B2 - Uneven pattern reading device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an uneven pattern reading device.

[0002]

2. Description of the Related Art In recent years, various types of cards which have been widely used are generally formed of plastic, and the name and number of the owner of the card are recorded as embosses on the card surface. As in this example, it is intended to automatically read an “irregular pattern” formed on the surface of the article with irregularities and to collate the irregular pattern.

[0003] The automatic reading of an uneven pattern is generally performed by forming an image of the uneven pattern on a light receiving surface of an image pickup device such as a CCD. In order to make the uneven pattern stand out, illumination of the uneven pattern is performed. A so-called "dark field illumination" is performed in which light is obliquely illuminated on the surface on which is formed.

As a device for reading a concavo-convex pattern, a device for performing the dark-field illumination using an optical fiber bundle has been known (Japanese Patent Application Laid-Open No. 59-197986). This device performs dark field illumination by using an optical fiber bundle, but it is not always easy to produce an optical fiber bundle to achieve this.

[0005]

SUMMARY OF THE INVENTION The present invention provides an optical fiber
An object of the present invention is to provide a novel uneven pattern reading device capable of reliably and satisfactorily reading an uneven pattern formed on a card surface or the like with a new dark-field illumination that does not depend on a bundle .

[0006]

According to the present invention, there is provided an uneven pattern reading apparatus which is formed on a surface of an object to be read which is sent in a predetermined direction along the reference surface in contact with or very close to the reference surface. Device that reads the uneven pattern that is present,
It has an imaging element, a reference plane member, an imaging lens system, a light source device, a reflection plane member, a light shielding member, a casing, and assembling means.

As the "image pickup device", a one-dimensional or two-dimensional one can be used. Therefore, the image sensor is specifically a line sensor or an area sensor.

The "reference plane member" is for forming a reference plane for the object to be read, and is transparent. At the time of reading, the object to be read is sent in a predetermined direction along the reference surface, in contact with or very close to the reference surface formed by the reference surface member.

The "imaging lens system" forms an imaging relationship between the reference surface and the light receiving surface of the image sensor, and forms an image of a concavo-convex pattern in contact with or very close to the reference surface on the light receiving surface of the image sensor.

The "light source device" has an annular structure, and is provided with the central axis of the annular substantially coinciding with the optical axis of the imaging lens system.

The "reflecting surface member" is provided in the vicinity of the reference surface, and has a ring-shaped "reflecting surface which is axially symmetric with respect to the optical axis of the imaging lens system and opens toward the imaging lens system". The light from the light source device is reflected to irradiate the object to be read obliquely.

The "light-shielding member" has a cylindrical shape, and is provided inside the light source device so that the optical axis of the imaging lens system substantially coincides with the central axis, and direct light from the light source device is applied to the reference surface. And stray light to the image sensor is blocked.

The "casing" incorporates and integrates the above-described image pickup device, reference surface member, imaging lens system, light source device, reflection surface member, and light shielding member.

"Assembling means" assembles the image pickup device, the reference surface member, the imaging lens system, the light source device, the reflecting surface member, and the light shielding member to the casing.

The above is the configuration of the device according to claim 1, which is the basic configuration of the present invention.

The positional relationship between the light source device and the reflecting surface member, and
It is preferable that the shape of the reflection surface of the reflection surface member is determined so that the inclination angle of the illumination light applied to the object to be read is distributed in a range of 0 to 20 degrees.

The annular light source device may be a "ring-shaped lamp" (claim 3) or "an LD (laser lamp on a substrate)".
(A diode) or an LED (light emitting diode) arranged in an annular shape ”(claim 4). As the ring lamp, for example, a ring fluorescent lamp or a ring xenon lamp can be used. When a ring-shaped lamp is used, a ring-shaped reflector may be used in order to effectively contribute the luminous flux emitted from the lamp in all directions to dark-field illumination.

In the case of a light source device in which LEDs and LDs are arranged in an annular shape on a substrate, a ring-shaped optical system is provided between the light source device and the reflecting surface member. Light of LD or each LED is converted to LD or L
It has an optical characteristic to make it uniform in the arrangement direction of the EDs ”(claim 5).

Further, in the apparatus according to claim 3 or 4,
A ring-shaped optical system is provided between the light source device and the reflecting surface member.
In the plane containing the optical axis of the imaging lens system,
The optical characteristics can be set to "suppress the divergence in the direction perpendicular to the optical axis ."

The above-mentioned reflecting surface member is constituted as “a circular transparent plate having a peripheral end surface tapered and a reflection film provided on this tapered portion”, and the tapered peripheral end surface portion is formed. The surface on the narrow side may be used as a reference surface, and the reflection surface member may also serve as the reference surface member. Furthermore, on the reflection surface of the reflection surface member, "a large number of grooves,
(Axisymmetrically with respect to the optical axis of the imaging lens system).

[0021]

When the light source device is turned on, the light is reflected by the reflecting surface member, becomes light inclined with respect to the reference surface, and obliquely illuminates the object to be read in contact with or very close to the reference surface.
At this time, the direct light from the light source device is blocked by the light blocking member from the reading target. Since the concavo-convex pattern is illuminated obliquely with respect to the illumination light, the edge portions of the concavo-convex pattern are brightly illuminated, thereby making the concavo-convex pattern stand out.

The illuminated image of the concavo-convex pattern is formed on the light-receiving surface of the image sensor by an image-forming lens system, read by the image sensor, and converted into a signal. The light shielding member blocks the image sensor.

The dark field illumination deteriorates as the angle of inclination of the light illuminating the concavo-convex pattern (the angle formed with respect to the reference plane) becomes larger and the illumination light becomes closer to the perpendicular to the reference plane. In order to make a concavo-convex pattern stand out favorably in dark-field illumination, the above-mentioned "tilt angle" is preferably in the range of 0 to 20 degrees.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments will be described with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. This embodiment is an apparatus for automatically reading the above-mentioned uneven pattern on the card surface. FIG. 1A is an explanatory cross-sectional view, and FIG. 1B is a BB cross-sectional view of FIG.

The casing designated by the reference numeral 7 in the drawing has a rectangular parallelepiped box shape in this embodiment, one of which is open in the longitudinal direction, and this open end is closed by the reference plane member 2. . The reference surface member 2 is a transparent plate, and in this embodiment, is a glass plate. The outer surface of the reference surface member 2 forms a reference surface, and the card 0 (object to be read) on which the concavo-convex pattern to be read is formed abuts or is very close to the surface 01 on the side on which the concavo-convex pattern is formed. Then, it is sent in the direction of the arrow.

At the innermost part of the casing 7, the two-dimensional image pickup device 1 is assembled to the casing 7 by a support 82. The imaging lens system 3 is mounted on the casing 7 between the imaging element 1 and the reference plane member 2 by the support member 81. The imaging lens system 3 is incorporated in a lens barrel, and the lens barrel is slidably fitted in a fitting hole of the support member 81. The imaging lens system 3 is configured such that the optical axis A
In a state where the position is adjusted by sliding in the x direction, and the reference surface and the light receiving surface of the image sensor 1 are in an image forming relationship, it is fixed to the support member 81 by an appropriate method.

The light source device 1 in which a large number of LEDs 41 are annularly arranged on the substrate 40 has a configuration in which the central axis of the annular array of LEDs substantially coincides with the optical axis Ax of the imaging lens system 3. And is incorporated in the casing 7. Furthermore, the hollow cylindrical light shielding member 6 is fitted and fixed to the support member 81. As is clear from the above description, both the support member 81 and the support 82 are assembling means.

A reflection surface member 5 is attached to a corner formed by the inner wall of the casing 7 and the inner surface of the reference surface member 2. The reflection surface member 5 has a ring-shaped reflection surface that is axially symmetric with respect to the optical axis Ax and that opens toward the imaging lens system 3. In this example, the shape of the reflection surface is a conical surface whose axis is the optical axis Ax.

The substrate 40 and the reflecting surface member 5 of the light source device 4 are
The board 40 and the reflection surface member 5 are fixed to the casing 7 at their outer peripheral surface portions by themselves.

FIG. 2A shows a state in which the reference surface side is viewed from the imaging lens system side. The dashed line indicates L of the light source device.
This is a ring formed by connecting the light emitting units of the ED. FIG. 2 (b)
Shows a state near the reference plane member in a state where the apparatus is virtually cut by a plane including the optical axis of the imaging lens system.

The inclination angle θ of the ring-shaped reflecting surface of the reflecting surface member 5 is set to 51 degrees. The divergence angle of the light emitted from the light emitting portion D of the light source device is 2α, and α is 6 degrees. The luminous flux from the light emitting section D is divergent, incident on the reflecting surface of the reflecting surface member 5 and is reflected. When the luminous flux is incident on the reference surface member 2 and transmitted therethrough, a not-shown concave / convex pattern of the object to be read is formed. Illuminate the surface obliquely. The inclination angles of the illumination light at points A, B and C are θ _A = 10 degrees and θ _B = 12, respectively.
Degrees, θ _C = 18 degrees, and good dark-field illumination is realized. Further, of the light from the light source device, light that does not directly contribute to dark-field illumination of the object to be read is blocked by the light blocking member 6 and does not act as stray light in reading.

Returning to FIG. 1, at the time of reading, the light source device 4 is turned on, the card 0 is sent in the direction of the arrow, and an image of the concave / convex pattern is formed on the light receiving surface of the image sensor 1, and the light receiving surface is formed at an appropriate timing. What is necessary is just to take in the above image and signal it. In this example, an area sensor is used as an image sensor. However, when a line sensor is used, the length direction of the line should be perpendicular to the drawing in FIG. ), The card may be read continuously while sending the card. With the apparatus of the above embodiment, extremely good reading of the uneven pattern was realized.

Hereinafter, a modified embodiment will be described. In the case of the embodiment shown in FIG. 1, when the distance between the LEDs constituting the light source device is large, or when the light source device is disposed close to the reflection surface member, the illumination light of each LED is used as a reference. It is conceivable that "unevenness" of the illumination light intensity is generated corresponding to the arrangement of the LEDs, being separated from each other on the surface.

As a simple method for solving such a problem, a method of providing a diffusing means such as ground glass or opalescent resin plate between the light source device and the reflecting surface member can be considered. Will decrease. In order to solve the "unevenness" of the illumination light intensity without reducing the illumination light amount, a ring-shaped optical system 90 as shown in FIG.
May be provided between the light source device and the reflection surface member. The optical system 90 is “a cylinder lens arranged in an annular shape with its generatrix direction (direction having no power) as the radial direction”.
It is. As shown in FIG. 3B, by providing the optical system 90 with the axis of symmetry of the optical system 90 substantially coincident with the center axis of the light source device, the luminous flux of the individual LEDs 41 can be adjusted in the LED arrangement direction (annular arrangement). , The light beams overlap each other to realize uniform illumination.

Instead of the cylinder lens, the ring-shaped optical system may have a trapezoidal cross-sectional shape on the ring as shown in FIG. In this case, the ring-shaped optical system has a trapezoidal prism arranged in a ring shape.

As the ring-shaped optical system, an optical system 91 having a sectional shape as shown in FIG. 3D can be used. The optical system 91, the central axis is matched with the center axis of the light source apparatus, when deployed between the light source unit and the reflecting surface member, in a plane including the imaging lens system optical axis, the light source
Divergence in the direction orthogonal to the optical axis in the plane can be suppressed. Therefore, for example, when a ring-shaped fluorescent lamp is used as the light source device, it is possible to effectively increase the light flux incident on the reflecting surface member from the light source device.

In the above embodiment, the casing has a rectangular parallelepiped box shape. However, the casing may of course be a cylindrical one. When such a cylindrical casing is used, a thick circular glass plate 20 as shown in FIG. 4 is tapered as shown in FIG. 4 as a reference surface member, and a reflection film 22 is formed on this tapered portion. Forming and tapering
The surface on the side where the attached peripheral part is narrowed (the lower side in FIG. 4)
By using the (surface) as the reference surface, it can be used as the reflection surface member 21 which also serves as the reference surface member. Of course, even when the casing has a rectangular parallelepiped box shape, it goes without saying that the reflection surface member also serving as the reference surface member can be appropriately modified and implemented.

As another example of a method for solving the "irregularity" of the illumination light intensity, as shown in FIG. 5 ((a) is a plan view, (b) is a cross-sectional view taken along line BB of (a)). , Reflection surface member 50
A large number of grooves 51 may be formed in a bevel gear shape axially symmetrically with respect to the optical axis of the imaging lens system. When the light from the light source device side is reflected by the reflecting surface, it enters at the edge of the groove 51.
Since the light is scattered in the direction perpendicular to the reflecting surface,
It is effective in reducing the number of people. Of course, the reflecting member 51 shown in FIG. 5 can be combined with various optical systems shown in FIG.

[0040]

As described above, according to the present invention, a novel concavo-convex pattern reading device can be provided. As described above, this device does not use an optical fiber bundle for illumination,
The structure is simple and can be easily implemented, and the uneven pattern can be read reliably and well.

Although an example of a card having a concavo-convex pattern as an object to be read has been described above, the device of the present invention is not limited to a card. As described above, the uneven pattern reading can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining one embodiment of the present invention.

FIG. 2 is a diagram illustrating dark-field illumination according to the embodiment of FIG.

FIG. 3 is a diagram illustrating a characteristic portion of another embodiment.

FIG. 4 is a diagram for explaining a characteristic portion of another embodiment.

FIG. 5 is a diagram for explaining a characteristic portion of still another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image sensor 2 Reference surface member 3 Imaging lens system 4 Light source device 5 Reflection surface member 6 Light shielding member 7 Casing 81 Assembling means

Claims (8)

(57) [Claims] An apparatus for reading an uneven pattern formed on a surface of a reading object sent in a predetermined direction along the reference surface in contact with or very close to the reference surface, comprising: Alternatively, a two-dimensional image sensor, a transparent reference surface member forming a reference surface, an image forming relationship between the reference surface and the image sensor light receiving surface, and forming an image of the uneven pattern on the image sensor light receiving surface. An imaging lens system for imaging; an annular light source device having an optical axis of the imaging lens system as a central axis; and an annular light source device provided in proximity to the reference plane and axially symmetric with respect to the optical axis of the imaging lens system. A reflecting surface member having a ring-shaped reflecting surface that opens toward the imaging lens system, reflecting light from the light source device, and serving as illumination light for obliquely irradiating the object to be read; and the light source device. Provided with the optical axis of the imaging lens system approximately aligned with the central axis And a cylindrical light-shielding member for preventing direct light from the light source device from irradiating the reference surface and blocking stray light to the imaging device; a casing; An assembling means for assembling an image lens system, a light source device, a reflecting surface member, and a light shielding member to the casing. 2. The apparatus according to claim 1, wherein the inclination angle of the illumination light applied to the object to be read is 0 to 20 degrees.
A concave-convex pattern reading device, wherein the positional relationship between the light source device and the reflecting surface member and the shape of the reflecting surface of the reflecting surface member are determined so as to be distributed in the range of . 3. The uneven pattern reading device according to claim 1, wherein the light source device is a ring-shaped lamp. 4. The uneven pattern reading device according to claim 1, wherein the light source device is configured by arranging LDs or LEDs in a ring shape on a substrate. 5. The light source device according to claim 4, further comprising a ring-shaped optical system between the light source device and the reflecting surface member, wherein the optical system transmits light of each LD or each LED constituting the light source device to an LD. Alternatively, the uneven pattern reading device has an optical characteristic that makes the LED uniform in the arrangement direction. 6. A ring-shaped optical system according to claim 3, further comprising a ring-shaped optical system between the light source device and the reflecting surface member, wherein the optical system emits light from the light source device to the reflecting surface member.
In a plane containing the optical axis of the imaging lens system,
A concavo-convex pattern reading device having an optical characteristic for suppressing divergence in a direction perpendicular to an axis . 7. The reflecting surface member according to claim 1, wherein the reflecting surface member has a tapered peripheral end surface of a circular transparent plate, and a reflecting film is provided on the tapered portion. An uneven pattern reading device, characterized in that the surface of the transparent plate on the side where the peripheral edge surface portion with the mark is narrowed is formed as a reference surface and also serves as a reference surface member. 8. The reflecting surface member according to claim 1, wherein a plurality of grooves are formed axially symmetrically with respect to the optical axis of the imaging lens system. An uneven pattern reading device characterized by the above-mentioned.