JPS5839385A - Discrimination of paper sheet - 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] The present invention relates to a method for discriminating paper sheets.

Pattern recognition-based discrimination methods have often been used to distinguish paper sheets such as banknotes, checks, and securities.

This method involves extracting features such as the shape or hue of characters and patterns printed on paper sheets, and comparing these with a reference to discriminate the type.

However, with the development and spread of copying machines in recent years, it has become possible to easily obtain highly accurate counterfeit bills by copying them, but the conventional discrimination method using pattern recognition requires advanced technology. There has been a problem in the ability to discriminate against counterfeit notes as described above.The object of the present invention is to provide paper that can easily and accurately distinguish paper sheets by utilizing the surface irregularities caused by the paper and printing method of the paper sheets. The object of the present invention is to provide a leaf discrimination method, in which a contact piece is made to slide against one plane of the paper leaf to be discriminated, and the type of paper leaf is determined by the temperature change caused by the M friction heat generated at that time. This is achieved by discrimination.

FIGS. 1 and 2 are front views showing essential parts of an embodiment and a modified example of the present invention, respectively, in which 1 is a sheet of paper to be distinguished, such as a banknote, and 2 is a sheet of spring material such as phosphor bronze. 8 is a temperature sensor such as a thermocouple or thermistor, 4 is a holding pad, 5 is a conveyance path, and 6 is a contact piece that also serves as a temperature sensor, such as titanium nitride (TiN) or cermet.

Table resistance temperature coefficient (T
It can be made using a thin film resistor with a large CR) and excellent wear resistance.

In one embodiment shown in FIG. 1, a contact piece is brought into contact with the front or back surface of the paper sheet to be discriminated (hereinafter, a banknote will be explained as an example) with a predetermined pressing force, and the banknote is moved along the conveyance path 5 in the direction of the arrow. move. If this is done, the surface of the banknote will have irregularities due to the quality (smoothness) of the banknote paper and the printing method, so the temperature of the contact piece will rise due to frictional heat. This temperature is the temperature at which the amount of heat generated and the heat dissipation are in equilibrium.

There are two types of printing patterns on banknotes: raised patterns printed by intaglio printing, and flat patterns printed by dry offset printing. Therefore, even if the banknote moves at a constant speed, the amount of heat generated is not uniform. Therefore, as shown in FIG. 8, the temperature of the contact piece is low in the area where there is no printing pattern and the area of dry offset printing (areas A and C in the figure), and is low in the area where the intaglio printing pattern is present (parts B).
) will be higher.

However, all patterns copied by a copying machine will produce mounds, regardless of the printing method of the original. Therefore, when such a counterfeit bill is checked according to this embodiment, friction increases and the temperature also increases in the pattern portion corresponding to the dry offset printing pattern of the genuine bill. .

Also, the amount of frictional heat generated differs when the paper quality is different.
The temperature will be different from that of genuine notes.

As described above, the temperature change due to frictional heat will be different unless not only the shape and hue of the pattern but also the paper quality and printing method are completely the same. This temperature change pattern has a unique pattern for each type of banknote. Therefore, by determining a unique temperature change pattern for each type of banknote in advance and comparing this with the temperature change detected by this embodiment, it is possible to accurately discriminate the type and authenticity of the banknote. The modification shown in FIG. 2 differs from the above embodiment only in that a temperature sensor is used as a direct contact piece, and the other parts and effects are exactly the same.

The contact piece and the temperature sensor may be separate as in the above embodiment, or one may serve as the other as in a modified example.

As explained above, according to the present invention, by utilizing the characteristics resulting from the combination of paper quality and printing method, it is possible to accurately distinguish the type and authenticity of paper sheets.

[Brief explanation of drawings]

1 and 2 are front views of main parts showing an embodiment and a modification of the present invention, respectively, and FIG. 8 is an example of a temperature change pattern of paper sheets detected according to the above-mentioned embodiment or modification. FIG. In the figure, 1 is a paper sheet, 2 is a contact piece, 8 is a temperature sensor,
6 indicates a contact piece that also serves as a temperature sensor. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] With the contact piece in contact with one plane of the paper sheet to be discriminated,
The sheet of paper is moved relative to the contact piece, a temperature change of the contact piece due to frictional heat generated during this movement is detected, and the type of the sheet of paper is discriminated based on the detected temperature change. A method for discriminating paper sheets, which is characterized by: