JPS62250347A - Detection of double feed of cut sheets and mixing-in of dissimilar sheet - Google Patents

Abstract

PURPOSE:To detect a double feed or the mixing of a dissimilar sheet by obtaining the sum of the absolute values of differences between the values of adjacent transmission factors at a plurality of the sample points of sheets and the subsequent sheet and comparing the mean value of added values at the sample points and the added value of the subsequent sheet. CONSTITUTION:A stacker 1 for bills feeds out them one by one by a feed roll 2 to stack the bills on a stocker 3. An LED4 and a photodetector 5 opposed to each other are provided in the neighborhood of the feed roll 2 and the quantity of light transmitted through the sample points on the bills are measured when the bills pass between the LED4 and the photodetector 5. The transmitted light quantity is calculated by inputting the output of the photodetector 5 to a CPU8 via an amplifier 6 and an A/D converter 7. Then, the sum of the absolute values of differences between the values of adjacent transmission factors at a plurality of the sample points of sheets and the subsequent sheet is obtained. The mean value of added values at the sample points and the added value of the subsequent sheet are compared with each other and, when last-said added value is extremely larger or smaller than the mean value, a double feed or the mixing of a dissimilar sheet is decided thereby.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for detecting double feeding or mixing of different types of sheets in a paper conveyance system that separates cut sheets one by one and conveys them sequentially.

(Prior Art) In banknote counters and the like, it has conventionally been common to detect electrical transmission or the mixing of different types of banknotes by utilizing fluctuations in the amount of light that passes through the banknotes.

However, the double feed detection system that uses the amount of transmitted light as described above assumes in advance the standard amount of light that passes through a specific banknote, and if the amount of transmitted light is significantly lower than the reference value, double feed is detected. If the type of banknotes to be counted changes, it is necessary to change the setting of the reference value, which is cumbersome to operate, and the detection optical system deteriorates over time. Since its characteristics fluctuate due to change, contamination, or temperature fluctuations, there is a high possibility of malfunctions and frequent maintenance is required.

(Object of the Invention) The present invention has been made in order to eliminate the defects of the conventional multi-feed detection device using a transmission optical system as described above, and to detect the weight of different sheets without changing the transmitted light amount reference value. To provide a method for detecting double feeding of cut sheets and mixing of different types of sheets, which enables feeding detection, has a double feeding detection rate less affected by characteristic fluctuations of an optical system, and does not require frequent maintenance. With the goal.

(Summary of the Invention) In order to achieve the above-mentioned object, a method for detecting double feeding or mixing of different types of sheets according to the present invention is performed as follows.

That is, the sheets fed into the device are sequentially passed through the detection optical system, and the absolute values of the differences between adjacent values of the amount of transmitted light at the multiple pull points of each sheet are added together and the average of these values is calculated. is calculated sequentially, and this average value is compared with the value obtained by adding the absolute value of the difference between adjacent value openings of 1° of transmitted light of multiple sample points on the next sheet, and the value is significantly lower than the average value or If the value is high, it is determined that double feeding or different types of sheets are mixed.

(Example) The present invention will be described in detail below based on an example shown in the drawings.

The second factor is a diagram showing a one-throw configuration of a banknote counter to which the method for detecting double feeding and mixing of different types according to the present invention is applied.

In the figure, reference numeral 1 denotes a stacker for banknotes to be counted, and a feed roll 2 sends out banknotes one by one and deposits them in a stocker 3. A light-emitting element 4 and a light-receiving element 5 are provided facing each other in the vicinity of the feed roll 2, and when a banknote passes between these two, the transmission +t is measured at a predetermined sample point on one banknote. To measure the amount of transmitted light, the output of the light receiving element 5 is sent to the CPU via an amplifier 5 and an A/L converter 7.
8 and performs necessary calculations. Here, it is determined whether or not there is double feeding. If it is determined that there is double feeding, the power supply circuit 10 of the drive system 9 of the feed roll 2 is shut off. Conventionally, the method of determining the presence or absence of double feeding is to assume in advance a reference amount of light that passes through a specific banknote, and if the amount of transmitted light is significantly lower than the reference value, it is determined that electrical transfer has occurred. Therefore, if the type of banknotes to be counted changes, it is necessary to change the setting of the reference value, which is cumbersome to operate, and the detection optical system deteriorates over time.

As mentioned above, there is a drawback that the characteristics change due to contamination or temperature fluctuations, resulting in a high possibility of malfunction.

In order to solve this problem, the present invention uses the following method.

In other words, in order to avoid the complexity of setting the transmitted light amount standard value due to changes in the type of banknotes to be counted, it is not necessary to set a specific standard value, and the transmitted era names at multiple sample points of the banknotes to be actually counted are adjacent to each other. The sum of the absolute values of the differences between the values Fu1 is sequentially averaged, and this average value is compared with the sum of the absolute values of the differences between adjacent values of the amount of transmitted light at a plurality of sample points of the next banknote. For example, when the upper and lower thresholds are off the predetermined thresholds, double feeding or dark-colored sheets may be mixed in when the threshold is abnormally low, and when the threshold is abnormally high, light-colored sheets may be mixed in. It is determined that a sheet different from the sheet to be counted has been mixed in, and in either case, the machine is stopped.

The above processing is executed by the CPLI installed in the machine, and the procedure is as shown in the flowchart of FIG. 1(a).

By the way, as a method for averaging the sum of the absolute values of the differences between adjacent values of the amount of light transmitted at a plurality of sample points of each banknote, as shown in Figure 1 (bl), You can simply take the arithmetic average of the sum of the absolute values of the differences between the transmitted light amounts and the adjacent value openings up to the first sheet, or (
As shown in cl, a method may be used in which the average of the first image and the sum of the @second image and the sum of the i@third image are averaged, and then the average of that and the total sum of the fourth image is calculated.

Alternatively, as shown in the same figure (dl) < FA A method of calculating the geometric mean of the first and second sheets and the sum of the third sheet, and then calculating the geometric mean of that and the sum of the fourth sheet. may also be used.

Since the present invention uses the method described above, there is no comparison target for measuring the amount of transmitted light on the g1th sheet. For this reason, if electrical transmission occurs in the first sheet, it may seem impossible to detect it, but in such a case, the sum of the absolute values of the differences between adjacent values of the amount of transmitted light for the next sheet will be greater than that of the first sheet. This is a significant difference and exceeds the thresholds set above and below the amount of transmitted light that was initially measured, so it is easy to determine that this is an abnormality and no problem will occur.

The present invention has been described above only in the case where it is applied to a banknote number counter, but it goes without saying that the present invention can also be applied to devices for identifying or counting the number of cut sheets of various types, such as a banknote identification device.

(Effects of the Invention) Since the present invention detects double feeding of cut sheets and mixing of different types of sheets using the method described above, there is no need to set judgment criteria for specific sheets, so different types of sheets can be processed. Even in such cases, there is no need to reset the criteria, which makes the operation easier and eliminates the risk of erroneous operation. Furthermore, since double feeding is not detected based on specific predetermined criteria, it is not affected by changes in characteristics due to aging, dirt, or temperature fluctuations in the optical system, so there is no possibility of malfunction. It also has the effect of being able to extend the interval between maintenance with extremely little maintenance.

[Brief explanation of drawings]

Figure 1 (al is a flowchart explaining the basic procedure of the method for detecting double feeding of cut sheets and mixing of different types of sheets according to the present invention; A flowchart diagram illustrating the averaging method, Figure @2, is a diagram showing the configuration of a banknote counter to which the present invention is applied.

Claims (4)

[Claims] (1) A counter or identification device for cut sheets such as banknotes sequentially averages the sum of the absolute values of the differences between adjacent values of the amount of light transmitted through a plurality of sample points of each cut sheet, and mth (m=1, 2, 3,...
...) Compare the average value up to the mth sample with the value obtained by adding the absolute value of the difference between adjacent values of the amount of transmitted light at the m+1 sample point, and this is the value up to the mth sample. Double feeding of cut sheets and mixing of different types of sheets is characterized in that if the cut sheet deviates from a predetermined threshold above or below the average value, the m+1th sheet is detected as a double feed or a different type of sheet. Detection method. (2) A value L_i (i=1, 2, ..., m；m
=1, 2,...) is the average of (L_1+L_2+
. . +L_m)/m) A method for detecting double feeding of cut sheets and mixing of different types of sheets according to claim (1), characterized in that the method is executed based on the formula: . . . +L_m)/m. (3) A value L_i (i=1, 2, ..., m；m
=1, 2,...) average value M_m is M_m=L
_m (m=1), Mm=(L_m+M_m_-_1)/
2 (m=2, 3, . . . ). A method for detecting double feeding of cut sheets and mixing of different types of sheets according to claim 1, wherein the method is executed based on the formula: 2 (m=2, 3, . . . ). (4) A value L_i (i=1, 2, ..., m；m
=1, 2,...) average value M_m is M_m=L
__m (m=1), M_m=√(L_m×M_m-1)(
The scope of claim 1 is characterized in that the execution is performed based on the formula m=2, 3, . . .
) Method for detecting double feeding of cut sheets and mixing of different types of sheets.