JP2804409B2 - Paper sheet reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for optically reading thin paper sheets such as banknotes.

2. Description of the Related Art In an automatic machine used for transfer of bills at a financial institution such as a bank, the inserted bills are read therein, and it is determined from the read result whether or not to accept the bills.

[0003]

2. Description of the Related Art A large number of sensors (light transmission type and reflection type) each having a combination of a light emitting element and a light receiving element are aligned across a paper sheet conveying path, and the corresponding light receiving element is sufficient. The light emission amount of each light emitting element is controlled so as to obtain a dynamic range.

FIG. 4 shows the relationship between the amount of light emitted and the amount of light received by the transmission sensor at the time of shipment of the apparatus and at the time of operation. If the light emission amount of the light emitting element increases to some extent in the absence of ()), the light reception amount of the light receiving element rises sharply from the light reception amount offset D (position A) in proportion to the light emission amount, and immediately saturates at position B.

Further, when the light emission amount of the light emitting element increases to some extent in a state where paper is present between the light emitting element and the light receiving element at the time of shipment of the apparatus, the light reception amount of the light receiving element becomes a light receiving amount offset D (position From A), it gradually rises in proportion to the amount of light emission, and saturates at a position C where the amount of light emission is large.

During operation of the apparatus, the amount of power to the light emitting element of each sensor is controlled so that a dynamic range between the light receiving amount E and the light receiving offset D lower than the light receiving saturation point B is obtained.

However, a sensor (light emitting element) changes with time.
Gradually deteriorates, and the light emission amount decreases, so that it becomes gradually difficult to secure the above dynamic range with the light emission amount determined at the time of shipment of the device.

For this reason, the inclinations of the straight line AB and the straight line AC at the time of shipment are previously stored and held in the memory.
At the time of operation of the apparatus, when the paper sheet has not entered between the light emitting element and the light receiving element (immediately before the user inserts the paper sheet into the apparatus), the amount of light received by the light receiving element is checked. The ratio between the amount of emitted light and the amount of received light (the slope of the linear characteristic without the transmission medium during operation indicated by the broken line in the figure) is obtained.

Further, when a sheet enters between the light emitting element and the light receiving element, a process of comparing the inclination of the straight line AB held in the memory with the obtained inclination of the broken line is performed.

When the inclination ratio of the two straight lines is obtained by the comparison processing, the light emission amount of the light emitting element is determined using this ratio and the inclination of the straight line AC held in the memory, and the corresponding light emitting element emits the same light. The energization is individually controlled so as to obtain the amount.

For example, when a certain sensor is deteriorated by 5% from the straight line AB, a straight line AF in which the straight line AC is further inclined by 5% is obtained, and the control target of the control target is obtained from the straight line AF and the position E. The light emission amount is determined.

As a result, a sufficient dynamic range is ensured regardless of the deterioration of the sensor, and a good read image is always obtained. Therefore, it is possible to accurately inspect a light and shade pattern such as a bill.

[0013]

However, in the prior art, since the deterioration of each sensor is individually corrected, if a paper chip remains, deterioration correction is excessively performed only for that part of the sensor. Therefore, the quality of the read image is reduced.

The present invention has been made in view of the above-described conventional circumstances, and an object of the present invention is to provide an apparatus capable of avoiding local overcorrection of sensor deterioration caused by remaining paper pieces. is there.

[0015]

In order to achieve the above object, an apparatus according to the first invention is configured as shown in FIG. 1. In the apparatus shown in FIG. 1, a light emitting element and a light receiving element are respectively combined. Sheet reading means 12 for reading sheets by a large number of sensors 10, and each sensor 1 when the sheets do not enter between the light emitting element and the light receiving element (optical path).
Average deterioration rate calculation means 14 for dividing the ratio between the light emission amount and the light reception amount of 0 by the reference ratio to obtain the average value of the deterioration rates of all the sensors 10.
And target light emission for setting a target light emission amount by multiplying the ratio of the light emission amount and the light reception amount of each sensor 10 when the paper sheet enters between the light emitting element and the light receiving element by the calculated deterioration rate average value. An amount setting unit 16, a sensor deterioration correcting unit 18 for controlling the light emission amount of each sensor 10 to a set target amount,
Having.

The apparatus according to the second aspect of the present invention is configured as shown in FIG. 2. The apparatus shown in FIG. 2 reads a sheet with a large number of sensors 10 each having a combination of a light emitting element and a light receiving element. A sheet reading means 12 for performing all the sensors by dividing the ratio between the light emission amount and the light reception amount of each sensor 10 when the sheet does not enter between the light emitting element and the light receiving element by a reference ratio; And an average deterioration rate calculating means 14 for obtaining an average value of the deterioration rates of the sensors 10 and a ratio between the light emission amount and the light reception amount of each sensor 10 when the paper sheet enters between the light emitting element and the light receiving element by a reference ratio. A correction adjustment value calculating means 20 for calculating a correction adjustment value, and a deterioration rate calculated based on a ratio between a light emission amount and a light reception amount of each sensor 10 when a sheet enters between the light emitting element and the light receiving element. Set the target flash output by multiplying the average value and the correction adjustment value. A light emission amount setting means 16, the sensor 1
And a sensor deterioration correcting means 18 for controlling the light emission amount of 0 to the set target amount.

Further, the apparatus according to the third invention is configured as shown in FIG. 3, and the apparatus shown in FIG. 3 reads a sheet with a large number of sensors 10 each having a combination of a light emitting element and a light receiving element. A sheet reading means 12 for performing all the sensors by dividing the ratio between the light emission amount and the light reception amount of each sensor 10 when the sheet does not enter between the light emitting element and the light receiving element by a reference ratio; And an average deterioration rate calculating means 14 for obtaining an average value of the deterioration rates of the sensors 10 and a ratio between the light emission amount and the light reception amount of each sensor 10 when the paper sheet enters between the light emitting element and the light receiving element by a reference ratio. Correction adjustment value storage means 22 for storing a standard correction adjustment value to be obtained by calculation, and a ratio between the light emission amount and the light reception amount of each sensor 10 when the sheet enters between the light emitting element and the light receiving element. Deterioration rate average value calculated and stored correction adjustment A target light emission amount setting means 16 for setting a light emission amount of the target multiplied by the door, the sensor deterioration correction means 1 for controlling the target amount of the relevant which are set the light emission amount of each sensor 10
8, and

[0018]

In the first invention, the deterioration rate of each sensor (10) (the ratio between the solid line characteristic AB and the operation characteristic without medium indicated by the broken line in FIG. Is calculated, an average value of the deterioration rates is calculated, and the deterioration amount of all the sensors is uniformly corrected by the average value.

For example, even if the number of sensors is 100 and only one of the sensors is deteriorated by 30% due to the remaining paper chip (assuming that the deterioration rate of the other sensors is 0%), all of the sensors are not used. The deterioration is corrected by 0.3%.

In the second invention, for example, the ratio between the solid line characteristic AB and the solid line characteristic AC in FIG. 4 is calculated as a correction adjustment value (a change in the inclination of the shipping characteristic caused by the presence or absence of the medium). The deterioration of all the sensors is uniformly corrected by the average value of the deterioration rates.

In the third invention, a standard correction adjustment value (statistically determined from a large amount of sampling data) is prepared in advance. Therefore, the correction adjustment value is treated as a fixed value, and the calculation process thereof is omitted.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a paper sheet reading apparatus according to the present invention will be described below with reference to the drawings.

FIG. 5 shows the structure of the embodiment. In the optical sensor unit 50 shown in FIG. 5, a transmission-type sensor array (a sensor in which the light-emitting surface and the light-receiving surface of the light-emitting device and the light-receiving device are opposed to each other by a straight line) is used. Paper sheets enter between the light emitting element and the light receiving element).

All the received light outputs obtained by the sensor section 50 are amplified to a predetermined level by the amplifier section 52 and then subjected to A / D conversion.
The signal is supplied to the conversion unit 54 and is converted into a digital signal in the A / D conversion unit 54.

The output of the A / D converter 54 (the light receiving output of each sensor) is supplied to a sensor corrector 56.
In the sensor correction unit 56, the light emission amount that is a control target of each sensor in the optical sensor unit 50 is calculated.

The light emission amount of the control target is calculated only when necessary by referring to the contents stored in the storage unit 58 in advance, and is written from the sensor correction unit 56 to the storage unit 60.

Further, the light emission amount of the control target written in the storage unit 60 is read out to the central processing unit 62, and the light emission amount of the light emitting element in each sensor of the optical sensor unit 50 is obtained by the light emission amount of the control target. Is controlled by the central processing unit 62.

Here, the sensor correction section 56 performs the processing shown in FIG. 6, FIG. 7 or FIG. 8 (first invention, second invention, third invention).
The present invention will be described below in order.

In FIG. 6, when a start of processing is requested from the central processing unit 62 (required when a user inserts paper sheets into the apparatus), an operation check of the optical sensor unit 50 is first performed. (Step 100), the light receiving output of each sensor is taken in (in FIG. 9, a broken line characteristic with no medium during operation which is slightly inclined from the solid line characteristic AB of the solid line is obtained).

Then, the data indicating the linear characteristic AB in FIG. 9 is read from the storage unit 58 and obtained at the time of the operation check, and the slope of each operating characteristic indicated by a broken line in FIG.
Are calculated, and an average value a (average value of the deterioration rates) of the calculation results (sensor deterioration amounts) is obtained (step 102).

Next, the sensor deterioration amount average value a is checked (step 104). If the sensor deterioration amount average value a is abnormal (NO in step 104), the fact is notified to the central processing unit 62. (Step 106).

If the sensor deterioration amount average value a is normal (YES in step 104), the linear characteristic AC shown in FIG.
Is read from the storage unit 58 and the linear characteristic A
The linear AF in FIG. 9 is determined by multiplying the inclination of C by the sensor deterioration amount average value a, and the operating point (a control target light emission amount common to all sensors) at which a necessary dynamic range can be secured on the linear AF is determined. It is determined (step 108).

Finally, the control target light emission amount is written into the storage unit 60 (step 110), and the central processing unit 62 controls the amount of current supplied to each sensor of the optical sensor unit 50 so that the light emission amount is obtained.

Therefore, even if only a small number of sensors are erroneously recognized to be greatly deteriorated due to the remaining paper piece, the excessive correction due to the deterioration is distributed to all the sensors without being localized. .

This is based on the premise that all sensors are manufactured at the same time and the deterioration proceeds at the same degree. Since the partial sensor deterioration abnormality due to the remaining paper piece is diluted as a whole, It is possible to always obtain a high quality read image.

Further, in the processing of FIG. 7, the calculation for calculating the correction adjustment value K (the change in the inclination of the shipping characteristic caused by the presence or absence of the medium) by dividing the inclination of the straight line AC by the inclination of the straight line AB in FIG. (Step 10
7) The deterioration of all the sensors is uniformly corrected using the multiplication value of the correction adjustment value K and the sensor deterioration average value a as a common coefficient (step 108). Therefore, the excessive correction of the sensor deterioration due to the remaining paper piece is distributed to all the sensors in a suppressed form.

In the process of FIG. 8, the correction adjustment value K in the process of FIG. 7 is prepared in advance in the storage unit 58 as a fixed value (for example, 0.3) (the straight line AB and the straight line AC).
Is collected in large quantities to calculate the correction adjustment value K, and the standard correction adjustment value K is finally determined by these statistical processes), and the calculation process of the correction adjustment value K is omitted (step 108). .

Accordingly, the processing of the apparatus is simplified, and the processing speed can be further increased. This is extremely advantageous for a simple device or a device whose processing speed is restricted. In addition, since all the sensors are manufactured at the same time and the characteristics of the straight line AB and the straight line AC are uniformed and the standard correction adjustment value K is statistically determined, the reliability of the correction adjustment value K Therefore, it is possible to obtain substantially the same effect as the processing of FIG.

[0039]

As described above, according to the present invention, the abnormalities in partial sensor deterioration due to the remaining paper fragments are dispersed and diluted throughout, so that a high-quality read image can be obtained regardless of the remaining paper fragments. Can always be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the first invention.

FIG. 2 is a diagram illustrating the principle of the second invention.

FIG. 3 is a diagram illustrating the principle of the third invention.

FIG. 4 is a sensor characteristic diagram illustrating a conventional technique.

FIG. 5 is a diagram illustrating the configuration of an embodiment.

FIG. 6 is a sensor characteristic diagram for explaining the operation of the embodiment.

FIG. 7 is a flowchart illustrating processing performed by a sensor correction unit.

FIG. 8 is a flowchart illustrating processing performed by a sensor correction unit.

FIG. 9 is a flowchart illustrating processing performed by a sensor correction unit.

[Explanation of symbols]

 Reference Signs List 50 optical sensor unit 52 amplification unit 54 A / D conversion unit 56 sensor correction unit 58 storage unit 60 storage unit 62 central processing unit

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ identification code FI G06F 15/64 325G (58) Investigated field (Int.Cl. ⁶ , DB name) G07D 7/00 B65H 7/14 G01B 11 / 30 G06T 1/00 G06T 7/00

Claims (3)

(57) [Claims] 1. A sheet reading means (12) for reading sheets with a large number of sensors (10) each having a combination of a light emitting element and a light receiving element; Average deterioration rate calculating means (14) for dividing the ratio between the light emission amount and the light reception amount of each sensor (10) when not entering the space by the reference ratio to obtain the average deterioration rate value of all the sensors (10). ) And the target light emission amount is set by multiplying the ratio between the light emission amount and the light reception amount of each sensor (10) when the paper sheet enters between the light emitting element and the light receiving element by the calculated deterioration rate average value. Paper light, comprising: a target light emission amount setting means (16) for controlling the light emission amount of each sensor (10); and a sensor deterioration correction means (18) for controlling the light emission amount of each sensor (10) to the set target amount. Reader. 2. A sheet reading means (12) for reading a sheet with a plurality of sensors (10) each having a combination of a light emitting element and a light receiving element; Average deterioration rate calculating means (14) for dividing the ratio between the light emission amount and the light reception amount of each sensor (10) when not entering the space by the reference ratio to obtain the average deterioration rate value of all the sensors (10). ), And a correction adjustment value for calculating a correction adjustment value by dividing the ratio between the light emission amount and the light reception amount of each sensor (10) when the sheet enters between the light emitting element and the light receiving element by a reference ratio. Calculation means (2
0) and the ratio between the light emission amount and the light reception amount of each sensor (10) when the sheet enters between the light emitting element and the light receiving element is multiplied by the calculated deterioration rate average value and the correction adjustment value. Target light emission amount setting means (16) for setting a target light emission amount; and sensor deterioration correction means (18) for controlling the light emission amount of each sensor (10) to the set target amount. Characteristic paper sheet reader. 3. A sheet reading means (12) for reading a sheet with a number of sensors (10) each having a combination of a light emitting element and a light receiving element; Average deterioration rate calculating means (14) for dividing the ratio between the light emission amount and the light reception amount of each sensor (10) when not entering the space by the reference ratio to obtain the average deterioration rate value of all the sensors (10). ), And a standard correction adjustment value to be obtained by dividing the ratio between the light emission amount and the light reception amount of each sensor (10) when the sheet enters between the light emitting element and the light receiving element by a reference ratio. And a correction adjustment value storage means (22) for storing the ratio of the light emission amount and the light reception amount of each sensor (10) when the paper sheet enters between the light emitting element and the light receiving element. The target for setting the target light emission amount by multiplying the value by the stored correction adjustment value Light emission amount setting means (16)
And a sensor deterioration correcting means (18) for controlling the light emission amount of each sensor (10) to a set corresponding target amount.