JPH02204891A - Method for detecting recessed and projecting part of medium - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a detection method for detecting irregularities formed on the surface of coins, medals, etc. (coins, etc.).

[Conventional technology]

Conventionally, the following characteristics are often used to identify coins and the like.

(1) Diameter (2) Thickness (3) Material (magnetic permeability, dielectric constant) [Problems to be solved by the invention] However, as unmanned machines such as vending machines become more widespread, there are more cases where counterfeit coins are used. It has become impossible to ignore this, and more precise identification of coins, etc. is desired. In other words, since counterfeiting is extremely easy with only the above three characteristics, various countermeasures have been proposed. For example, there are those that use an image sensor to read the pattern on the surface of a coin, and those that use a color sensor to detect differences in color.

However, these items can be counterfeited by simple methods such as pasting a paper copy of the coin pattern onto the coin, and currently there is no definitive solution.

Therefore, an object of the present invention is to provide a method that can easily detect the presence or absence of unevenness.

[Means to solve the problem]

A medium with an uneven pattern on its surface is conveyed in a fixed posture, and an irradiation means for irradiating light at a predetermined irradiation angle onto the surface of the medium on the conveyance path is directed in the same direction as the conveyance direction or in a direction that forms a predetermined angle therewith. A plurality of them are arranged, and these irradiation means irradiate the medium with light in a predetermined order, the resulting reflected light is received by the light receiving means, and the unevenness on the medium is detected based on the received light output.

[Effect]

By utilizing the fact that the received light output changes depending on the order of light irradiation in each direction, the presence or absence of relief-like unevenness can be detected relatively easily.

〔Example〕

FIG. 1 is an explanatory diagram for explaining the invention in detail.

That is, if there is a convex portion T as shown in the same figure (a),
In the state of light incidence, the measurement point P is exposed to light,
It is in a bright state as shown in the same figure (b). On the other hand, the light incidence L! In this state, the measurement point P is in the shadow, and is in a dark state as shown in FIG. Note that in the case of a printed matter with a simple pattern without irregularities, the illuminance does not vary depending on the direction of incidence of light, so detection is performed here by focusing on this difference. Furthermore, if the influence on the generation of shadows is small, a slight horizontal tilt of the medium can be tolerated.

Figure 2 shows the configuration of the sensor section.

That is, the sensor section 1 here has two light emitting sections 11 that irradiate light onto the surface of the coin C, and a light receiving sensor 1 in the center thereof.
It is constructed by arranging 2. The reason why the light receiving sensor 12 is provided in the center is to receive scattered light rather than specularly reflected light. Note that P indicates a measurement point.

Therefore, when the two light emitting parts 11 blink alternately as shown in FIG. )
It changes as shown in FIG. 3(D) depending on the protrusion T shown in FIG. The presence or absence of unevenness can be detected from the change in brightness of the light-receiving sensor output, and it is possible to identify whether the incident light is concave or convex based on the phase relationship between the incident lights L+ and Lx. In some cases, it is also possible to identify patterns by comparing them with standard patterns.

FIG. 4 shows the relationship between incident light and detectable irregularities. In the case of a convex part, as explained above, in the case of a concave part, both the incident light and L are set to "ON", and the detection of a concave part is performed by checking whether there is a shadow on the measuring point P. It can be seen that this is possible.

Although the above example has been described in which there are two light incident directions and one light receiving sensor, these numbers can be increased as appropriate. Figure 5 shows examples in which the incident directions of light are in two directions and in four directions. In other words, when the incident directions of light are in two directions, unevenness occurs in the direction perpendicular to the conveyance direction of the medium, as shown in the figure (a). In some cases, it can be detected, but in cases where there are unevenness in a direction parallel to the conveyance direction, detection becomes difficult. Therefore, the same figure (b)
If the incident directions of light are set to four directions as shown in FIG.

Note that a two-dimensional image can also be obtained by arranging two or more light receiving sensors, for example, in an array.

〔Effect of the invention〕

According to the present invention, the most essential feature of a relief-like stamped pattern on a coin or the like can be extracted optically, which provides the advantage of enabling precise identification.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram for explaining the invention in detail, and FIG.
The figure is a schematic diagram showing the configuration of the sensor section, Figure 3 is an explanatory diagram to explain the relationship between incident light and the light receiving sensor output, and Figure 4 is an explanatory diagram to explain the relationship between incident light and detectable irregularities. FIG. 5 is an explanatory diagram for explaining examples in which the incident directions of light are two directions and four directions. Description of symbols 1...Sensor part, 11...Light emitting part, 12...Light receiving part, T...Protrusion, P...Measurement point, L, , L2. L3
．． L4...Incoming light, C...Coin. Tsutomu 27 Tomi 4 Tsutomizu mm1 revised view/'L4 - Kozue Gyori direction

Claims (1)

[Claims] 1) A medium with an uneven pattern on its surface is conveyed in a constant posture, and an irradiation means that irradiates light onto the medium surface on the conveyance path at a predetermined irradiation angle is directed in the same direction as the conveyance direction or at a predetermined angle thereto. A plurality of them are arranged in the same direction, and these irradiation means irradiate the medium with light in a predetermined order.
A method for detecting unevenness on a medium, characterized in that the reflected light obtained as a result is received by a light receiving means, and unevenness on the medium is detected based on the output of the received light.