JP2007011653A - Method and device for reading embossed character string - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an embossed character string reading device, capable of accurately reading of an embossed character string formed on a card by a dark-field illumination method. <P>SOLUTION: The embossed character string reading device 1 illuminates the surface 3 of the card 2 through the use of first illumination light sources 12, 13 with a parallel light at the illumination angle of 12 degrees from both the sides of the longitudinal direction of the card, illuminates the surface 3 of the card 2 through the use of second illumination light sources 14, 15 with the parallel light at an illumination angle of 12 degrees, in a direction orthogonal to the aligning direction of the embossed character string 4 from both the sides of the short side direction of the card, and illuminates with a diffusion light in the aligning direction of the embossed character string 4. An image is photographed, where the contour of each embossed character, in the embossed character string 4 that extends in the longitudinal direction of the card, is clearly embossed from the background of the card without missing sections, so that the embossed character string 4 on the surface 3 of the card 2 is read accurately. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method and apparatus for reading an embossed character string formed on the surface of a card such as a credit card by a dark field illumination method, and particularly illuminates the card surface so that a sharp reflected image of the embossed character outline can be taken. The present invention relates to an improved technique.

A card such as a credit card or a bank card is formed with an identification number string (hereinafter referred to as an embossed character string) made up of numerals, English characters, and the like by embossing. As such an embossed character string reading mechanism, an optically reading method is known instead of a method (imprint) of mechanically copying the embossed character string. As an optical reading method, a dark field illumination method in which the surface of a card on which an embossed character string is formed is illuminated from an oblique direction, and a reflected image of the edge of the embossed character that emerges thereby is read by an image sensor such as a CCD camera. It has been known. Such reading methods are disclosed in Patent Documents 1 and 2.
JP-A-5-89276 Japanese Utility Model Publication No. 5-66762

  In order to cut out the contour image of each embossed character captured by the dark field illumination method from the card background image by image processing so that each embossed character can be recognized accurately, the embossed character string is configured. Therefore, it is necessary to form a reflection image in which the outline of each embossed character is clearly raised from the card background. Further, it is necessary to obtain a reflection image of the embossed character so that the thickness of the contour of the embossed character is uniform in each part.

  Here, in a card such as a credit card, an embossed character string forming area is defined by a standard, and the embossed character string extends in the card long side direction. For this reason, for example, the illumination conditions are greatly different between the embossed character located at both ends of the embossed character string and the embossed character located at the center. That is, the irradiation angle and the amount of illumination light are different.

  In addition to this, in a credit card or the like, the background (card surface portion) of the embossed character string is diverse such as a color printing surface and a hologram surface. If the card background is different, it may not be possible to capture an image in which the embossed character outline is clearly raised from the card background.

  Conventionally, reading failure due to a difference in illumination conditions of each part of an embossed character string formed on a card, reading failure due to a difference in card background such as a hologram, and the like are not considered. For this reason, there is a problem that the embossed character string formed on the card cannot be read accurately.

  In view of these points, an object of the present invention is to propose an embossed character string reading method and apparatus that can accurately read an embossed character string extending in the long side direction on a card surface by a dark field illumination method. is there.

In order to solve the above problems, the present invention provides an embossed character string reading method for reading an embossed character string formed on the surface of a card by a dark field illumination method. Illuminate the card surface with illumination light at a predetermined irradiation angle with respect to the card surface from both sides in the direction orthogonal to the character string arrangement direction, photograph the card surface including the embossed character string, and Identify each embossed character in the embossed character string,
The irradiation angle of the illumination light is set based on the state of the card surface and the height and interval of the convex portions of the embossed characters.

  In the method of the present invention, since the card surface is illuminated from the four circumferences of the card, a reflected image of each contour portion of the embossed character formed on the card surface can be reliably obtained. In addition, since the illumination light irradiation angle is determined according to the state of the card surface, the height of the convex portion of the embossed character, and the interval, the contrast between the card background and the embossed character outline is sufficiently high, Thus, it is possible to obtain a reflection image in which the outline of the embossed character is not missing. As a result, embossed characters can be read accurately.

  Here, the font of embossed characters used in a card such as a credit card is generally Farrington 7B. In this case, in order to prevent the illumination light to the other by one of the adjacent convex portions in the embossed character from being partially lost in the reflected image of the outline of the embossed character, the illumination angle of the illumination light Is preferably about 12 degrees.

  Next, in order to accurately read the embossed character string by the dark field illumination method, it is desirable to illuminate so that the contour line of each embossed character of the embossed character string becomes a reflected image having a uniform thickness in each part. For this purpose, it is necessary to illuminate each embossed character with the same amount of illumination light at the same irradiation angle. For this purpose, it is desirable to use parallel light as illumination light.

  However, when illuminated with parallel light from the direction of the embossed character string and from the direction orthogonal thereto, the contours extend in a direction not orthogonal to each parallel light, such as the corners of the embossed character. Sufficient reflected light cannot be obtained from the portion, and a reflected image having such a blurred outline portion is obtained, which may reduce the reading accuracy of the embossed characters. Therefore, it is desirable to use diffused light as illumination light in order to sharpen the contours such as the corners of each embossed character.

  Here, if diffused light is used as the illumination light from both sides of the embossed character example, the variation in illumination light irradiation angle and the amount of illumination light for each embossed character increase according to the distance from the illumination light source. The outline of the embossed characters in each part does not become a reflection image having a uniform thickness. In the case of illumination from both sides in the direction orthogonal to the direction of the embossed character string, the difference in distance from the illumination light source is only one embossed character. The thickness of the reflected image of the contour portion does not vary greatly.

  Therefore, the method of the present invention is characterized in that the illumination light from both sides in the arrangement direction of the embossed character strings is parallel light.

  Further, in order to secure the amount of reflected light from the contour portion that is not parallel to either the direction of the embossed character string in the embossed character or the direction orthogonal to the embossed character string, the embossed character string is As the illumination light from both sides in the direction orthogonal to the arrangement direction, the light that becomes diffuse light is used.

  Next, the present invention provides an embossed character string reading device for reading an embossed character string formed on the surface of a card by a dark field illumination method, a card setting unit for setting a card to be read, and the card setting unit A first illumination light source that illuminates the surface of the card placed on the card from both sides of the embossed character string arrangement direction, and the surface of the card installed on the card placement unit in the arrangement direction of the embossed character string A second illuminating light source that illuminates from both sides of the orthogonal direction; and an imaging unit that is located above the surface of the card installed in the card installation unit and photographs the illuminated card. The irradiation angle of the illumination light from the illumination light source and the second illumination light source to the surface of the card is such that the surface state of the card and the convex portion of the embossed character of the embossed character string It is characterized height, and that it is set on the basis of the interval.

  Here, it is desirable that the illumination angle of the illumination light is about 12 degrees.

  The illumination light from the first illumination light source is preferably parallel light, and the illumination light from the second illumination light source is preferably diffused light.

  As described above, in the embossed character string reading method and apparatus of the present invention, in order to read the embossed character string formed on the card surface, the embossed character string is arranged on both sides of the embossed character string arranging direction and the embossed character string arranging direction. The card surface is illuminated from both sides in the orthogonal direction, and the illumination angle of illumination light from each direction is set to an appropriate value, preferably 12 degrees. By illuminating the card surface in this way, the contrast between each contour portion of the embossed character and the card surface is large, and a clear reflection image with no omission in the contour of the embossed character can be obtained. Can be read accurately.

  Further, in the present invention, the embossed character string on the card surface is illuminated with parallel light from both sides in the arrangement direction and illuminated with diffused light from both sides in the direction orthogonal thereto. When illuminated in this way, each contour portion of each embossed character in the embossed character string can be acquired as a reflected image having a clear and uniform thickness. Therefore, the reading accuracy of the embossed character string can be increased.

  Therefore, according to the present invention, it is possible to realize a method and apparatus that can accurately read an embossed character string formed on a card by a dark field certification method.

  Hereinafter, an example of an embossed character string reading device for a credit card to which the present invention is applied will be described with reference to the drawings.

  FIG. 1A is a schematic configuration diagram showing the main part of the embossed character string reading device of this example, and FIG. 1B is an explanatory diagram showing the arrangement of the illumination optical system. The embossed character string reader 1 of this example is for reading an embossed character string 4 formed on the surface 3 of a credit card 2 (hereinafter simply referred to as “card 2”) by a dark field illumination method. .

  The embossed character string reading device 1 includes a card setting unit 11 for setting a card 2 to be read and a surface 3 of the card 2 set in the card setting unit 11 in the card long side direction (the embossed character string 4 The first illumination light sources 12 and 13 that illuminate from both sides of the arrangement direction) and the surface 3 of the card 2 installed in the card installation unit 11 are in the card short side direction (direction orthogonal to the arrangement direction of the embossed character strings 4). Second illumination light sources 14 and 15 that illuminate from both sides and a CCD camera that is located above the surface 3 of the card 2 installed in the card installation unit 11 and is an imaging device that captures a reflected image of the illuminated card surface 3 16.

  The captured image of the CCD camera 16 is supplied to the control unit 17, and the contour of each embossed character of the embossed character string 4 is cut out from the captured image in the image processing unit 18 of the control unit 17, and the identification unit 19 is based on the extracted contour information. The embossed characters constituting the embossed character string 4 are identified. The read embossed character information is output from the control unit 17 to an external device such as a host computer via the communication interface 20.

  In FIG.1 (b), the 1st illumination light sources 12 and 13 of the right and left of the card | curd 2 are each provided with LED31 which is a point light source, and the collimating lens 32 which changes the diffused light from here to parallel light. The parallel light emitted from the collimating lens 32 is used as illumination light to illuminate the embossed character string 4 on the card surface 3 from both sides in the arrangement direction. If the 1st illumination light sources 12 and 13 are arrange | positioned according to the arrangement position of the embossing character string 4, as shown to a figure, the embossing character string 4 can be illuminated efficiently. In this example, the parallel light illuminates the surface 3 of the card 2 with an irradiation angle θ of 12 degrees.

  In FIG. 1B, the other upper and lower second illumination light sources 14 and 15 of the card 2 are each a plurality of LEDs 33 arranged at regular intervals and one LED 33 arranged on the emission side of these LEDs 33. The cylindrical lens 34 is provided. The cylindrical lens 34 has positive refractive power in a direction perpendicular to the card surface 3 (perpendicular to the arrangement of the embossed character strings 4), and in a direction perpendicular to the card surface 3 (the direction in which the embossed character strings 4 are arranged). Has no refractive power. In this example, after the diffused light from each LED 33 passes through the cylindrical lens 34, the embossed row 4 on the card surface 3 as parallel light in the direction perpendicular to the card surface 3 (perpendicular to the arrangement of the embossed character strings 4). It is designed to focus and irradiate the part of Thereby, the irradiation light from the 2nd illumination light sources 14 and 15 is condensed only on the embossed character string 4 part, and can be irradiated efficiently. In the direction orthogonal to this (the direction parallel to the card surface, the direction in which the embossed character strings 4 are arranged), the entire embossed row 4 on the card surface 3 is irradiated with the diffused light. Thus, the 2nd illumination light sources 14 and 15 irradiate the embossed character string 4 with diffused light from both sides of a card short side direction (direction orthogonal to the arrangement direction of the embossed character string 4). The parallel light in the direction perpendicular to the card surface 3 illuminates the card surface 3 with an irradiation angle θ of 12 degrees.

  The card 2 reading operation is started, for example, by inputting a reading command via the input unit 21 after the card 2 is set in the card setting unit 11. The controller 17 drives the illumination light sources 12 to 15 through the LED driver 22 and then drives the CCD camera 16 to capture an image of the illuminated card surface 3 and process the captured image. The embossed character string 4 is read.

  FIG. 2 is an explanatory diagram showing the specifications of the card 2 that is the reading target of the apparatus 1 of this example. As shown in FIG. 2 (a), the standard of the card 2 is determined by ISO / IEC7810, and the middle position of the surface 3 of the card 2 is embossed with a maximum of 19 characters as shown in FIG. 2 (b). It is defined as area 4a. Further, as shown in FIG. 2C, the font F of embossed characters formed in the embossed area 4a is also defined by the standard, for example, Farrington 7B is used. The font F is basically composed of vertical segments and horizontal segments in which each character basically extends in the vertical direction and the horizontal direction, and inclined segments that connect the intersections. The embossed character string 4 extends in the card long side direction X, and each embossed character is formed so as to be up and down in the card short side direction Y.

  In the font F, the smallest segment interval is the number “4”. As shown in FIGS. 3A and 3B, the interval between the vertical segments a and b in the numeral “4” is the narrowest and is 0.88 mm. The height of the convex portions of the vertical segments a and b formed by embossing is determined to be 0.48 + 0 / −0.18 according to the standard, and the worst conditions for irradiating the edges of adjacent segments are 0.48 mm and 0.3 mm. Therefore, in the case where the illumination light L is irradiated obliquely from above the card surface 3, in order to irradiate the illumination light to the edges of both adjacent segments a and b, as shown in FIG. It is desirable that the incident angle θ of the above is 11.56 degrees or more.

  The embossed character string reading device 1 of this example can clearly obtain an image of the embossed character string 4 formed on the card 2.

  First, in FIG. 1B, the vertical segments of each embossed character of the embossed character string 4 are generated by the parallel illumination light from the left and right first illumination light sources 12 and 13 arranged on both sides of the card 2 in the long side direction. The edge can be illuminated with less influence of the difference in distance from the light source. Further, in FIG. 1B, the edge of the horizontal segment of each embossed character of the embossed character string can be illuminated by illumination light from the upper and lower second illumination light sources 14 and 15 arranged on both sides in the short side direction of the card 2. . Further, since the second illumination light sources 14 and 15 are diffused light when viewed along the direction of the surface 3 of the card 2, the second illumination light sources 14 and 15 are inclined segments at the intersection of the vertical and horizontal segments of each embossed character in the embossed character string. The edge can be illuminated. In addition, since the illumination angle θ of each illumination light is set to 12 degrees, the edge of each segment can be illuminated even in a font in which the interval between adjacent vertical segments is narrow, such as the numeral “4”. . Therefore, the outline of each embossed character in the embossed character string can be reliably photographed by the camera.

  Further, the illumination light irradiation angle θ is made as small as possible within the range in which the edge of the contour of the embossed character string 4 can be irradiated. Therefore, the amount of reflected light from the background (card surface portion) of the embossed character string 4 incident on the CCD camera 16 can be suppressed as much as possible. Therefore, an image having a large contrast between the contour of the embossed character string and the background of the card 4 can be acquired. Further, the influence of the background pattern of the card 4 and the hologram can be reduced.

  Further, since the illumination light from both sides in the card long side direction is parallel light, the embossed characters at each position of the embossed character string 4 can be acquired as contour images having the same brightness and the same thickness. . That is, as shown in FIG. 4 (a), when the illumination light is diffused light, the luminous flux spreads according to the distance from the light source, and as the distance from the light source increases, the illumination angle of the illumination light decreases, , The amount of irradiation light decreases. For this reason, in the embossed character string 4 extending in the card long side direction, the illumination conditions for the embossed characters near the light sources located at both ends thereof are significantly different from the illumination conditions for the embossed characters located in the center. End up. In this case, even if the contour image on one side can be sharpened, there is a problem that the contour image on the other side is lost. On the other hand, as shown in FIG. 4B of this example, when parallel light is used, the irradiation angle and the irradiation light amount in each part are substantially the same without being affected by the distance from the light source. become.

  As described above, by using the embossed character string reading device 1 of this example, it is possible to capture an image in which the outline of the embossed character is clearly raised from the card background. In addition, the contour of each embossed character can be photographed as a contour image having substantially the same brightness and thickness. Therefore, it is possible to accurately read the embossed character based on the photographed image.

(Other embodiments)
Next, FIG. 5 shows a method for miniaturizing the illumination light source of the embossed character string reader 1. As shown in FIG. 5A, the illumination light sources 11 and 12 are composed of a single LED 31 and a single collimating lens 32, and the LED 31 and the collimating lens 32 are changed according to the refractive power of the collimating lens 32. A space W1 is provided between them. If this interval can be narrowed, the illumination light sources 11 and 12 can be reduced in size, which is effective in reducing the size of the embossed character string reader 1.

  For this purpose, as shown in FIG. 5B, the collimating lens 32 is divided into, for example, a plurality of lenses 32a arranged in a line, and a plurality of LEDs 31 are arranged to face each lens 32a. Good. In this way, the distance W2 between the LED 31 and the lens 32a can be narrowed, and accordingly, the embossed character string reading device can be reduced in size.

  Further, as shown in FIG. 5C, the collimating lens 32 is omitted, and a parallel light irradiation LED 31a that emits parallel light is used as a light source lamp instead of a normal LED 31 that emits diffused light. Also good.

  Of course, the illumination light sources 14 and 15 can be downsized by adopting the methods shown in FIGS. 5B and 5C.

It is a schematic block diagram of the embossed character string reader to which this invention is applied. It is explanatory drawing which shows the specification of the card of reading object. It is explanatory drawing which shows an example of an embossed character. It is explanatory drawing which shows the difference of diffused light and parallel light. It is explanatory drawing which shows the method for size reduction of an illumination part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Embossed character string reader, 2 card | curd, 3 surface, 4 embossed character string, 11 card installation part, 12, 13 1st illumination light source, 14, 15 2nd illumination light source, 16 CCD camera, 17 control part, 18 Image processing Part, 19 identification part, 20 communication interface, 21 input part, 22 LED driver, 31, 33 LED, 32 collimating lens, 34 cylindrical lens

Claims (7)

In the embossed character string reading method of reading the embossed character string formed on the surface of the card by the dark field illumination method,
Illuminate the card surface with illumination light at a predetermined irradiation angle with respect to the card surface from both sides in the direction in which the embossed character strings are arranged and from both sides in a direction orthogonal to the arrangement direction of the embossed character strings,
Photographing the card surface including the embossed character string,
Identify each embossed character of the embossed character string from the captured image,
An embossed character string reading method, wherein the illumination light irradiation angle is set based on the state of the card surface and the height and spacing of the convex portions of the embossed characters. In claim 1,
An embossed character string reading method, wherein an irradiation angle of the illumination light is about 12 degrees. In claim 1 or 2,
The embossed character string reading method, wherein illumination light from both sides of the embossed character string arrangement direction is parallel light. In claim 3,
The embossed character string reading method, wherein illumination light from both sides in a direction orthogonal to the direction of arrangement of the embossed character strings is diffused light. In the embossed character string reading device that reads the embossed character string formed on the surface of the card by the dark field illumination method,
A card installation unit for installing a card to be read;
A first illumination light source that illuminates the surface of the card installed in the card installation unit from both sides in the direction of arrangement of the embossed character strings;
A second illumination light source that illuminates the surface of the card installed in the card installation unit from both sides in a direction orthogonal to the direction in which the embossed character strings are arranged;
An image pickup unit that is located above the surface of the card installed in the card installation unit and photographs the surface of the illuminated card;
The irradiation angle of the illumination light from the first illumination light source and the second illumination light source with respect to the surface of the card depends on the surface state of the card and the height and spacing of the convex portions of the embossed characters of the embossed character string. An embossed character string reading device set based on the above. In claim 5,
An embossed character string reading device, wherein an illumination angle of the illumination light is about 12 degrees. In claim 5 or 6,
Illumination light from the first illumination light source is parallel light,
The embossed character string reading device, wherein the illumination light from the second illumination means is diffused light.

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