JPS6146583A - Length detection for sheet papers - 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 Technical Field This invention relates to an improvement in a method for detecting the length of paper sheets, which is carried out in pill checkers and the like.

Tb) Prior Art and Its Disadvantages In order to detect the length of paper sheets such as banknotes in pill checkers and the like, a lens system and a light receiving element array such as COD are usually used. Figure 3 shows the detection method. A lens system 2 and a light-receiving element array 3 are arranged above the banknote 1, and a light source 4 is arranged below the banknote 1. With this arrangement, the banknote 1 is When the banknote is conveyed in the direction of the arrow shown in , a grayscale image generated by the light source 4 passing through the banknote 1 is formed on the light receiving element array 3 via the lens system 2.The control connected to the light receiving element array 3 In the section, the length of the paper sheet is detected based on the number N of elements from the relationship that the number N of elements in the imaging range is proportional to the length of the banknote 1.

However, in the above method, as long as the lens system 2 is used, the image becomes distorted, and the number N of elements and the length of the banknote 1 do not have an accurate proportional relationship. In particular, the longer the banknotes are, the greater the effect of distortion by the lens system 2 becomes, and pill checkers and the like that handle long banknotes have the drawback of extremely large errors.

(C) Object of the Invention An object of the invention is to provide a method for detecting the length of paper sheets, which solves the above-mentioned disadvantages by a simple method.

(d1 Structure and effect of the invention) This invention provides that when the number N of elements in the imaging range is greater than a certain value, the length of the detected paper sheet increases as the number N increases. It is characterized by adding correction values.

According to this invention, by configuring as described above,
Since the effects of lens distortion are easily compensated for by adding correction values, it is possible to accurately determine the length of a paper sheet without using a highly accurate lens system.

(e) Embodiment FIG. 2 is a block diagram of an apparatus for implementing the length detection method according to the present invention. The output of each element in the light-receiving element array 3 is transferred to a multiplexer 5, subjected to parallel-to-serial conversion in synchronization with a clock 6, and guided to an amplifier 7, where it is amplified to an appropriate level. 8 is the signal amplified by the amplifier 7 and the preset threshold level R.
Compare with EF. This comparator 8 can detect only the part of the signal train from the amplifier 7 that is within the imaging range, and outputs an "H" signal to the counter 9 within that range. The counter 9 counts the number of clocks in the imaging range detected by the comparator 8 and sends it to cPUIO. CPU10
Then, the length of the paper sheet is detected based on the counted value.

FIG. 1 is a flowchart showing the length detection operation in the CPU10. First, in step n1, the count value from the counter 9 is obtained and used as length data of the number of elements N-9 in the imaging range. Subsequently, in step n2, it is determined whether the number of elements N is greater than or equal to a certain value n1. If it is less than or equal to n1, the number N of elements is directly determined as length data. n
l is the minimum value that causes an error in the number of elements N due to lens system distortion. If the number of elements N is greater than or equal to a certain value n1, then in step n3 it is compared with a value n2 larger than n1. If the number N of elements is smaller than n2, that is, if it is greater than or equal to a certain value n1 and less than n2, a positive correction value 1 is added to the number N of elements in step n5. Further, if the number of elements N is n2 or more, the number of elements N is n2 in step n4.
If the number of elements N is less than or equal to n3, a positive correction value 2 is added to the number of elements N in step n6.
is added. Further, if the number of elements N is greater than or equal to n3, a positive correction value of 3 is added in step n7.

In this way, the number of elements N in the imaging range is set to a constant value n1.
In the above case, a positive correction value is added to the number N of elements as the number N of elements increases.

Through such an operation, data closer to the actual length of the banknote can be obtained.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing the operation of an apparatus implementing the length detection method according to the present invention. Moreover, FIG. 2 is a block diagram of the same device, and FIG. 3 (A). (B) shows a method for detecting the length of paper sheets using a lens system and a light-receiving element array, in which (A) is a side view and (CB) is a front view. 1-Banknote (an example of paper sheet) 2-Lens system, 3-Light receiving element array.

Claims (1)

[Claims] (1) In a method in which an image of a paper sheet is formed on an array of light-receiving elements using a lens system, and the length of the paper sheet is detected from the number of elements in the imaging range, the number of elements in the imaging range is N. is above a certain value, a positive correction value is added to the detected length of the paper sheet as the number of elements N increases. .