JPS6239483Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field This invention relates to a paper leaf reading device used in a banknote authenticity determination device, etc., and in particular, the invention relates to a paper leaf reading device used in a banknote authenticity determination device, etc. Relating to a device for reading .

(b) Prior Art To read paper sheets such as banknotes, an image sensor or the like is generally used to read a pattern at a specific position on the paper sheet. A conventional reading device of this type is proposed in, for example, Japanese Patent Laid-Open No. 143298/1983. In conventional reading devices such as the one proposed in Japanese Patent Application Laid-Open No. 143298/1984, the position of the reading sensor is fixed and the sensor output pattern is compared with a pre-stored reference pattern.

On the other hand, to determine the authenticity of paper sheets such as banknotes,
It is necessary to read multiple track patterns on paper sheets. Therefore, in the device shown in the above-mentioned Japanese Patent Application Laid-open No. 54-143298, a plurality of reading sensors are provided, and in order to reduce the number of reference patterns for inserting paper sheets in four directions (front and back, forward and reverse), Each sensor position is determined to read data at a position symmetrical to the central axis of the paper sheet.

(c) Problems to be solved by the invention However, although the above-mentioned reading device has the advantage of reducing the number of reference patterns and reducing the memory capacity, if the paper sheet shifts vertically during transportation, The problem arises that the sensor reads different patterns. In order to prevent this, it is necessary to accurately regulate the width of the paper sheets so that they do not shift.
This method not only requires a complicated mechanism, but also has the drawback of making paper jams more likely to occur. Another possible countermeasure is to prepare reference patterns for the range of permissible deviation of the reading position, but this has the disadvantage that the storage capacity of the reference patterns becomes large and the time required for comparison increases. . In particular, this method has a problem in that its drawbacks become more pronounced as the number of read tracks increases.

This idea maintains the concept of reading data at positions symmetrical to the central axis of paper sheets, while also being able to always read patterns at a constant position even if the paper sheets shift during transportation. It is an object of the present invention to provide a reading device for paper sheets that does not require a large storage capacity and requires a short time for comparison.

(d) Means for solving the problem This invention consists of an image sensor that is arranged perpendicular to the conveyance direction of paper sheets and scans the paper sheets perpendicular to the conveyance direction, and an image sensor that scans the paper sheets perpendicular to the conveyance direction. An edge detection means for detecting the upper and lower edge timing of the paper sheet, and counting scanning clocks of an image sensor between the upper and lower edges of the paper sheet, and counting n bits (n is an arbitrary number) corresponding to the entry width of the paper sheet. first and second n-ary counters that are output when the content is set; a counter value preset for presetting a value of the predetermined value for the n bits in the second n-ary counter when the lower edge of the paper sheet is detected by the edge detection means; and means for sampling and holding the output of the image sensor at the time of output of the first and second n-ary counters, and configured to read a pattern of tracks symmetrical to the central axis of the conveyed paper sheet. It is characterized by what it did.

(e) Operation In the paper sheet reading device according to this invention, when paper sheets are conveyed, they are sequentially read while being scanned perpendicularly to the conveyance direction by the image sensor. On the other hand, the first n-ary counter is preset with a predetermined value when the upper edge is detected by the edge detection means, and the second n-ary counter is preset with the predetermined value for n bits when the lower edge is detected. The complement value of the predetermined value is preset. 1st
And the second n-ary counter overflows and outputs an output when the count value reaches n. When the counter outputs an output, the image sensor output at that time is sampled and held and read.

FIG. 1 is a diagram for explaining the above operation in an easy-to-understand manner.

Now, assume that (ni) is preset in the first n-ary counter as the above-mentioned predetermined value at t1 when the upper edge is detected. From this point on, the first n-ary counter starts counting the scanning clocks, and when it counts i, the count value reaches n, overflows, and outputs.
That is, at t2, the first data of track A to be read is read.

Next, when t3 is reached, a lower edge is detected, and at this timing, the second n-ary counter is preset to i, which is the complement value of (ni) corresponding to n.

When entering the second scan, the first scan is performed at t4 as in t1.
(n-i) is preset in the n-ary counter of . From this time, the first n-ary counter starts counting, overflows at t5, and the image sensor output at that time is read. Also, the second
The n-ary counter also starts counting from t4, but the
Since i is preset at t3, an overflow occurs when (ni) is counted from t4. That is, when it reaches t6, it overflows and the image sensor output at that time is read.
As a result, the first data of track B is read at t6 of the second scan.

By repeating the above operations, the patterns of tracks A and B are read.

By such an operation, it is possible to read the pattern of tracks symmetrical about the central axis of the paper sheet. Also, as is clear from the above operation,
Even if the paper sheet shifts vertically during transportation, the timing intervals of t1, t2, t3, ... are exactly the same, and the positional relationship between each timing and the paper sheet is maintained accurately. Therefore, track A,
Pattern B is read.

(f) Effect of the invention As described above, according to this invention, the first n-ary counter is preset with a predetermined value, and the second n-ary counter is preset with the complement of the predetermined value for n bits. By providing advance counters and taking out the image sensor output when these counters overflow, it is possible to easily read out the track pattern symmetrical to the central axis of the paper sheet.
In addition, since the counter described above counts between the top and bottom edges of the paper sheet, it has the advantage that it can always read the correct track pattern even if the paper sheet shifts in the vertical direction while it is being conveyed. be. Moreover,
Since the reading position is always accurate, there is no need to prepare a plurality of reference patterns that cover the allowable deviation amount of the position. Therefore, the storage capacity does not increase, and the time required to compare patterns does not increase.

(g) Embodiment Figure 2 shows a paper sheet reading device that is an embodiment of this invention, Figure A is a schematic diagram showing the arrangement of each element, and Figure B shows the positional relationship between banknotes and image sensors. FIG.

In FIG. 2, a banknote 1 is regulated so that its longitudinal edge is perpendicular to the transport direction P, and is transported between two guide members 4 arranged in parallel so as to face each other. Approximately in the center of the guide member 4, there is an illumination lamp 6 on the lower side, a condenser lens 7 on the upper side, and an image sensor 5 perpendicular to the plane of the paper.
and are arranged. On the banknote 1, a track A to be read is set at a portion extending a length i from the upper edge, and a track B to be read is set at a portion extending a length i from the lower edge. If the length of the banknote in the width direction is n, then
The complement of i to n is (ni). The patterns of tracks A and B are based on the image sensor 5's x,
Read by cell y.

Next, the control section of this device will be explained.

FIG. 3 is a block diagram of the control circuit of the device. Further, FIG. 4 is a timing chart showing the operation of the control circuit.

Oscillator 10 is the basic clock that regulates the operating timing of this control circuit. The output is given to the counter 11 that supplies the start signal b to the image sensor 12, the image sensor 12, and counters to be described later. When the counter 11 receives a reading command from a circuit (not shown), it starts counting, and when it reaches a predetermined value, the image sensor 1
A start signal b is output to 2. When the image sensor 12 receives the start signal b, it accumulates a charge in each cell according to the amount of incident light, and outputs an analog level proportional to the amount of charge accumulation in time series in synchronization with the clock signal a. The time series output of the image sensor 12 is set to be an output for one scan of a banknote in 16 bits. Therefore, the image sensor 12 outputs 16 bits as one scan output for each scan.

The output of the image sensor 12 is amplified to a predetermined level by an amplifier 13, and the amplified signal c is introduced into a comparator 14 and compared with a reference voltage V.
This reference voltage is set to a threshold value sufficient to detect when the amount of light incident on the image sensor 12 is reduced due to a banknote. Therefore, comparator 1
4 detects the top edge of the banknote 1.

The differentiation circuit 16 detects the rising edge of the output of the comparator 14 and forms a differentiation pulse. The differentiation circuit 15 detects the rising edge of the output of the comparator 14 and forms a differentiation pulse. That is, the differentiating circuits 16 and 15 form an upper edge signal d and a lower edge signal h when detecting the upper edge and lower edge of the banknote 1, respectively.

The hexadecimal counter 18 is loaded with a value set by the setting switch 17 when the upper edge signal d rises. Further, when the output of the comparator 14 is "high", the clock a is counted.
Similarly, the hexadecimal counter 23 loads the output of the complement circuit 22 at the rising edge of the lower edge signal h. Similarly to the counter 18, when the output of the comparator 14 is "high", the clock a
count. The complement circuit 22 has a counter 1 for "16" which is the number of bits required for scanning one banknote.
This is a circuit that calculates the complement value of the contents of 8. Therefore, the complementary value of the contents of the counter 18 when the lower edge of the bill is detected is preset in the counter 23, and the next scan will be counted from that preset value. counter 1
The carry signals e and i of 8 and 23 are changed to the pulse width of clock a by gates 19 and 24, and are guided to sample and hold circuits 20 and 25 as sample signals f and j. The sample and hold circuits 20 and 25 sample and hold the amplified signal c when receiving the sample signals f and j,
It is output as track pattern signals g and k.

Next, the operation of this device will be explained.

First, when the banknote 1 is conveyed to a position where it is read by the image sensor 12, the counter 1
Start signal b is output from 1, and image sensor 1
2 scan is started. The image sensor 12 is
As shown in FIG. 4, the signal c is output in synchronization with the clock a, but when the signal c lower than the reference voltage V is output, the comparator 14 outputs "high" and the differentiator 16 outputs the upper edge signal. form d. Therefore, the value previously set in the setting switch 17 is preset in the counter 18 at the rising edge of the upper edge signal d. Preset value is "8"
It is set to a larger value and smaller than "15" (hexadecimal F), and in this embodiment, it is set to "12" (=C).

After the counter 18 is preset, it then starts counting up in synchronization with clock a. And the counter contents are “C” → “D” →
When the next clock is input, the counter 18 overflows at the rising timing and outputs the carry signal e. When the carry signal e is output, the gate 19 outputs the sample signal f, and the sample hold circuit 20 samples and holds the image sensor output output at that timing. As a result, in the amplified signal c in FIG. 4, the signal g shown by hatching is output as a track pattern signal.

On the other hand, when one scan of banknotes is completed, comparator 1
Since the output of 4 becomes larger than the reference voltage V, the lower edge signal h is generated by the differentiating circuit 15 when the output exceeds the reference voltage. As mentioned above, when this lower edge signal h is generated, the complementary value of the counted contents of the counter 18 is preset in the counter 23, but the counted contents of the counter 18 at this time are as shown in FIG. It has a value of "12" (=C). Therefore, "3", which is the complement value of "12" (=C) to "15" (=F), is the counter 2.
Preset to 3.

Thus, in the first scan, the track pattern signal g is output and the counter 23 is preset to "3".

Next, when the second scan is performed, the counter 18 changes from "C" to "D" to "E" in the same way as above, and at the rising edge of the next clock, a carry signal e is output and the sample signal is form f. The operation at this time is exactly the same as the operation during the first scan, so the sampled signal is
This is a signal adjacent to the first sampled signal shown above (see FIG. 2). On the other hand, unlike the previous time, the counter 23 starts counting from the preset value "3" after the comparator 14 outputs "high". When 12 counts are reached, a carry signal i is output, and the amplified signal c at that time is sampled. That is,
As shown in FIG. 4, the signal of the portion 5 bits upward from the bottom edge of the banknote 1 is output as the track pattern signal k.

The third and subsequent operations are performed in exactly the same manner as the second operation. Therefore, the signal output by the sample and hold circuit 20 is always a signal 5 bits below the top edge of the banknote 1, and the signal output by the sample and hold circuit 25 is always at the bottom edge of the banknote 1. This is the signal of the portion that is 5 bits higher than the current value. That is, except for the data obtained by the first scan, the data obtained by the subsequent scans can be a pattern of tracks symmetrical about the central axis of the banknote 1. Therefore, by setting a pattern that ignores data based on the first scan as a reference pattern, it is possible to easily determine the authenticity of banknotes from the data obtained by each sample and hold circuit. Moreover, even if the banknote shifts vertically during transportation,
The data to be sampled and held is always at a position 5 bits below the top edge and 5 bits above the bottom edge. This is because the counters 18 and 23 count only between the upper and lower edge signals. Therefore, the correct track pattern can always be read even if the banknote conveyance condition is poor.

In the above embodiment, the preset value of the setting switch was set to "12", but a value other than this may be used. This value can be changed by simply changing the setting switch 17, and no other operations are necessary.

As above, use two counters,
Furthermore, by using means for presetting appropriate values and complement values for these counters, it is possible to easily read the pattern of tracks symmetrical about the central axis.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the operation of this invention. FIG. 2 shows a bill reading device that is an embodiment of this invention, FIG. 2A is a schematic diagram showing the arrangement of each element, and FIG. 2B is a diagram showing the positional relationship between the bill and the image sensor. 3 is a block diagram of the control circuit of the same device, and FIG. 4 is a timing chart showing the operation of the control circuit. 1...Banknote, 12, 5...Image sensor, 1
8...(first) counter, 23...(second)
Counter, 17... Setting switch (for preset), 20, 25... Sample hold circuit, 22
... Complement circuit, A, B... Track.

Claims (1)

[Scope of utility model registration request] an image sensor disposed perpendicularly to the conveying direction of paper sheets and scanning the paper sheets perpendicularly to the conveying direction; an edge detection means for detecting upper and lower edge timings of the paper sheets during output from the image sensor; The first and second n-ary signals are output when the scanning clocks of the image sensor are counted between the upper and lower edges of the paper sheet, and the counting content is n bits (n is an arbitrary number) corresponding to the width of the sheet entry. a counter; when the top edge of the paper sheet is detected by the edge detection means each time the paper sheet is scanned, a predetermined value is preset in the first counter; counter value presetting means for presetting a complementary value of the predetermined value for the n bits in the second n-ary counter when a lower edge of a leaf is detected;
A reading device for paper sheets, comprising: means for sampling and holding the output of the image sensor at the time of output of the advance counter, and reading a track pattern symmetrical to the central axis of the transported paper sheet.