JPS62128379A - Seal stamp reading method - Google Patents

Abstract

PURPOSE:To prevent generation of reading mistake due to an image pickup device by lighting a seal stamp engraved on an object by plural optical sources from a different mutually while shifting the time mutually and synthesizing the shadow given to the seal stamp by each light source. CONSTITUTION:A seal stamp letter 14 engraved on the surface of an object 12 is lighted by the 1st light source 16 and shadows 42a, 42b are formed to engraved strips 14a, 14b. The OR between the picture information of the 1st picture stored in the 1st memory buffer 30 and the picture information of the 2nd picture stored in the 2nd memory buffer 32 is obtained by a synthesis circuit 34 comprising an OR gate circuit, and the picture information as a shadow image of an engraved letter 14 being the synthesis between shadows 42a, 42b of the 1st picture and a shadow 44 of the 2nd picture is outputted to a discriminator 38 as the output from the synthesis circuit 34. Thus, the seal stamp is accurately and easily read.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for reading a stamp, and more particularly, the present invention relates to a method for reading a stamp engraved on an object. The present invention relates to a stamp reading method that makes it possible to optically read and identify a pattern made of the stamps by combining the shadows of the stamps.

Image processing technology that optically reads character patterns, shape patterns, etc. and deciphers the patterns through pattern matching saves the labor of data entry and interpretation by workers, and also processes data accurately and quickly. In recent years, it has attracted attention in various fields as something that can be obtained.

By the way, in the conventional optical character reading method, for example, a character pattern printed on the surface of an object is read using an imaging device such as a vidicon camera, and the character pattern is compared with pre-stored character pattern data for interpretation. .

In this case, the character pattern is recognized by the imaging device as a difference in reflectance between the character pattern and the object on which it is marked, that is, a contrast between brightness and darkness on the object, and is converted into an image signal.

However, a character pattern formed by such a difference in reflectance becomes unclear if the surface of the object on which the character pattern is marked becomes dirty or if the character pattern becomes blurred. There was a risk of reading errors occurring due to

Therefore, one possible method for preventing such reading errors is to engrave a character pattern on the surface of the object. In this case, unlike the case of a character pattern printed on an object, there is no difference between the reflectance of the object and the reflectance of the marking, so it is impossible to read the character pattern using conventional imaging methods. For this reason, a method is adopted in which the character pattern formed by marking is irradiated with light from an oblique direction to artificially form shadows and then the character pattern is read. As a result, there is no risk that the read character pattern will become unclear due to dirt or the like on the surface of the object, and the occurrence of reading errors by the imaging device is reduced.

However, when character patterns are engraved, shadows may not be formed in the engraved area depending on the direction of light irradiation.
Therefore, there is a drawback that the shape of the stamped character pattern that can be clearly read by this method is extremely limited.

The present invention has been made in order to overcome the above-mentioned disadvantages, and it is possible to make various patterns of markings by illuminating the markings with a plurality of light sources from different directions at different times and composing the shadows. It is an object of the present invention to provide a method for reading a stamp that can be read accurately and easily, and also at a very low cost using a conventional optical reader.

In order to achieve the above object, the present invention provides a marking reading method for optically reading a pattern of markings engraved on an object, the markings being illuminated by a plurality of light sources from different directions at different times. The pattern of the stamp is read by combining the shadow information given to the stamp by each of the light sources.

Next, preferred embodiments of the stamp reading method according to the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 1, reference numeral 10 indicates a stamp reading system applied to the stamp reading method according to the present invention. and a second light source 16.18;
an imaging device 20 that images the engraved characters 14; and a light source 1.
6.18 and controlling the imaging device 20 to print the stamped characters 14.
It basically consists of an image processing device 22 that reads the image. Note that the engraved character 14 is shown in an H shape as an example.

The first and second light sources 16 and 18 are composed of light emitting elements such as LEDs, and the first light source 16 is arranged diagonally above the object 12 so that its leading axis is orthogonal to the side stripes 14a and 14b of the engraved character 14. Configure it. Further, the second light source 18
2, and is configured such that its front axis is perpendicular to the optical axis of the first light source 16 and the side strip 14C. That is, in this case, the first light source 16 and the second light source 18 are
It will be readily understood that they may be arranged 90° offset from each other.

On the other hand, (the imaging device 20 is a vidicon camera or CCD
It is composed of an image sensor, etc., and is arranged above the object 12 so as to be able to image the entire area of the engraved character 14.

FIG. 2 shows a block circuit diagram of the image processing device 22 shown in FIG. 1. In this image processing device 22, a sampling circuit 24 divides a two-dimensional image captured by the imaging device 20 into a predetermined number of pixels, and extracts image information in each pixel as an electrical signal, for example, a voltage value. The binarization circuit 26 binarizes the image information extracted by the sampling circuit 24 by associating O or I data depending on the brightness of each pixel. These sampling circuit 24 and binarization circuit 26
Its operation is controlled by a control circuit 28.

On the other hand, the first memory buffer 30 and the second memory buffer 32 temporarily store the image information binarized by the binarization circuit 26 in response to a control signal from the control circuit 28, respectively. Further, the synthesis circuit 34 is a circuit for calculating the logical sum of the image information stored in the first memory buffer 30 and the second memory buffer 32, and is constituted by, for example, an OR gate circuit.

The standard pattern data storage device 36 stores a plurality of standard pattern data that have been binarized in advance according to a predetermined engraved character pattern, and the reading device 38 combines the standard pattern data with the combining circuit 34. The engraved characters 14 are compared with the binarized information, and the reading result is outputted to the output device 40. Here, the pattern matching operation performed by the reading device 38 is called pattern matching, and is one of the most powerful methods of pattern recognition.

Next, a method of reading a stamp using the stamp reading system 10 configured as described above will be explained based on the flowchart shown in FIG.

First, under the control action of the control circuit 28, the first light source 1
Turn on 6 (STPI). At this time, the engraved characters 14 engraved on the surface of the object 12 are illuminated by the first light source 16, and as shown by diagonal lines in FIG.
Shadows 42a and 42b are formed. As a result, object 1
Contrast occurs on the surface of the object 12, and the imaging device 20 images the surface of the object 12 including these shadows 42a and 42b as a first image (SrF2).

The first image captured by the imaging device 20 is divided into a predetermined number of pixels by a sampling circuit 24 in the image processing device 22.

Here, when a vidicon camera is used as the imaging device 20, the imaging device 20 scans the first image based on a horizontal synchronization signal and a vertical synchronization signal output from the control circuit 28, and depending on the brightness and darkness of the first image. Image information in the form of voltage values or current values is output to the sampling circuit 24 as time series data. At this time, the sampling circuit 24 temporally discretizes the image information using a timing pulse from the control circuit 28, and converts the image information of the first image into image information divided into a predetermined number of pixels.

Next, the image information of the first image divided into a predetermined number of pixels by the sampling circuit 24 is converted into binary information according to the brightness of each pixel by the binarization circuit 26 (SrF
2). That is, a comparator or the like determines whether the voltage value or current value, which is the image information of each pixel, exceeds a predetermined darkness value, and converts it into O or 1 information.

The image information of the first image binarized in this way is
Temporarily stored in the memory buffer 30 (SrF4
).

Then, under the control of the control circuit 28, the first light si
6 is turned off (SrF5), the second light source 18 is turned on (SrF6). At this time, the engraved characters 14 engraved on the surface of the object 12 are illuminated by the second light source 18, and appear like a shadow 44 through the side stripes 14C, as shown by diagonal lines in FIG. In this state, the imaging device 20 has a shadow 44
(Sr
F2).

This second image is divided into predetermined pixels by the sampling circuit 24 as in the case of the first image described above, and then the image information of each pixel is converted into an O or I signal by the binarization circuit 26 ( SrF8).

The image information of the second image binarized by the binarization circuit 26 is stored in the second memory buffer 32 (SrF9
), the second light source 18 is turned off (STPIO).

Next, the logic between the image information of the first image (see FIG. 4) stored in the first memory buffer 30 and the image information of the second image (see FIG. 5) stored in the second memory buffer 32 is explained. The sum is determined by a synthesis circuit 34 consisting of an OR gate circuit (STPII). As a result, the synthesis circuit 3
As shown in FIG. 6, the output from 4 is the image information fi as a shadow image of the stamped character 14, which is a combination of the shadows 42a and 42b of the first image and the shadow 44 of the second image, which is output by the reading device 38.
is output to.

The reading device 38 compares this synthesized image ↑n information with a standard pattern previously stored as a binary signal in the standard pattern data storage device 5TP12), and sends the result to the output device 40. Output (S T P 13)
. Note that the output device 40 displays the read characters or transfers a signal corresponding to the read characters to the next stage control device or the like.

Here, the reading device 38 is a device applied to conventional pattern matching, and for example, compares the image information from the synthesis circuit 34 and the standard pattern data from the standard pattern data storage device 36 using a comparator or the like, The results are output to the output device 40. It is also possible to extract only the main part information of the character to be interpreted from the synthesis circuit 34 and compare it with the standard pattern data. In this way, it becomes possible to recognize characters according to the permissible reading error range of the stamped characters 14.

In the above embodiment, two light sources 16 and 18 are used, but it is also possible to use three or more light sources depending on the shape of the engraved characters. In that case, the memory buffer may be expanded according to the number of light sources, and
The configuration may be such that the image information captured by each light source is sequentially combined by the combining circuit 34 without adding a memory buffer. Furthermore, it goes without saying that the marking to be read may be of any shape other than characters.

As described above, according to the present invention, a stamp marked on an object is illuminated by a plurality of light sources from different directions at different times, and the shadows appearing on the stamp are optically read by each of the light sources, and the image information thereof is read. The logical sum is calculated based on the following.

Therefore, it becomes possible to read stamps without contrast, which constitute character patterns, shape patterns, etc., with great accuracy and ease. Furthermore, since the markings are illuminated from different directions by a plurality of light sources, markings of various shapes can be reliably read. moreover,
Since a device for reading a stamp can be configured using a conventional optical reading device, there is an advantage that the method for reading a stamp according to the present invention can be realized at a very low cost.

Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to these embodiments, and various improvements and changes in design can be made without departing from the gist of the present invention. Of course.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a stamp reading system applied to the stamp reading method according to the present invention, FIG. 2 is a block circuit diagram of an image processing device applied to the stamp reading method according to the present invention, and FIG. A flowchart illustrating the stamp reading method according to the present invention; FIG. 4 is an explanatory diagram showing a state when stamped characters are illuminated by the first light source in the stamp reading method according to the present invention; FIG. 5 is a flowchart explaining the stamp reading method according to the present invention; FIG. 6 is an explanatory diagram showing a state when the stamped characters are illuminated by the second light source in the stamp reading method. FIG. 6 is an explanatory diagram showing a shadow image of the stamp synthesized by the stamp reading method according to the present invention. 10... Stamp reading system 12... Object 14.
... Engraved characters 16.18... Light source 20.
...Imaging device 22...Image processing device FI
G, 5 14c

Claims (2)

[Claims] (1) A marking reading method that optically reads a pattern of markings engraved on an object, in which the markings are illuminated by a plurality of light sources from different directions at different times, and each of the light sources illuminates the markings. A method for reading a stamp, characterized in that the pattern of the stamp is read by combining provided shadow information. (2) In the method according to claim 1, a first shadow image is obtained by illuminating the marking with a first light source, and then the first light source is turned off, and the first light source is abbreviated as the first light source. Obtaining a second shadow image by illuminating the stamp from a perpendicular direction with a second light source, and reading the pattern of the stamp by calculating the logical sum of the first and second shadow images. How to read the engraving.