JP2576291B2 - Light transmission data reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an improvement of the light transmission data reader <br/>. In a light transmission data reader that inspects paper sheets such as banknotes, the entire paper sheet is divided into minute regions, and the light transmission amount of each minute region is measured by a plurality of light transmission sensors arranged in an array, After the amplification, A / D conversion, and image processing are performed, the validity, authenticity, falsification, falsification, and the like of the paper sheet are determined by comparing the data with dictionary data prepared in advance.

In such a light transmission data reading device, it is necessary to improve the reliability of light transmission data.

[0003]

2. Description of the Related Art FIG. 4 is a diagram for explaining reading of light transmission data, FIG. 5 is a diagram showing a conventional example (No. 1), FIG. 6 is a diagram showing a conventional example (No. 2), and FIG. 8), FIG.
Is a diagram showing a conventional example (part 4).

FIG. 4 is an explanatory view of a light transmission data reader for inspecting the density, chipping, etc. of the paper sheet 20. In the figure, an upper light transmission sensor unit 21 and a lower light transmission sensor unit 22
Has a plurality of light-emitting sensors or light-receiving sensors arranged linearly at a predetermined pitch. The light-emitting sensor and the light-receiving sensor are arranged so as to face each other to form a one-dimensional light transmission sensor. Paper sheets between the two sets of light transmission sensors
By reading the light transmission data at predetermined intervals while transporting the sheet 20, light transmission data in which the entire surface of the paper sheet 20 is divided into minute regions can be obtained. (Data Sampling) FIG. 5 shows a conventional example (No. 1), and is a cross-sectional view (the same applies to FIGS. 6 to 8) as viewed from the direction A in FIG. In this method, the light-emitting sensor 4 is set in one of the upper and lower light transmission sensor units, and the light-receiving sensor 5 is set in the other, so that light is emitted and received only in the same direction. However, in this method, depending on the material of the paper sheet 20, there is a material that transmits light from the front to the back well, but does not transmit much of the reverse, so that a satisfactory judgment cannot be made unless the loading direction of the front and back is limited. There is.

FIG. 6 shows a conventional example (No. 2).
In order to solve the drawback of the conventional example (Part 1), a light emitting sensor and a light receiving sensor are dispersed vertically and a method of repeating light emission and light reception in a plurality of units vertically. However, this method has a drawback in that a vertical stripe (a stripe in the transport direction) or color unevenness occurs in a plurality of units because a difference occurs in transmittance from top to bottom or from bottom to top. Furthermore, since the sensor pitch is about 1.5 mm in the horizontal direction even if it is repeated in a plurality of units, a sensor structure in which light-emitting sensors and light-receiving sensors are alternately arranged has poor yield, lacks reliability, and costs. Also disadvantageous. Therefore, a new problem arises in that the light emitting sensor and the light receiving sensor have to be provided on the upper and lower surfaces, respectively, and the method using only a part thereof is inefficient.

FIG. 7 shows a conventional example (part 3).
The light emitting sensor and the light receiving sensor are set alternately up and down. With this method, the disadvantage of the conventional example (1) of limiting the upper and lower feeding methods was almost eliminated, but on the contrary, the vertical stripes of the conventional example (2) were alternately generated, and the image quality was degraded. The disadvantages of having problems and of being inefficient still remain.

FIG. 8 shows a conventional example (No. 4). In the structure of the conventional example (No. 3), data is sampled using all the light-emitting sensors and the light-receiving sensors, and upper and lower materials are formed. In order to cancel the difference, the average of the light transmission data from upper to lower and from lower to upper is taken as the light transmission data at that position. As a result, the disadvantage of poor efficiency is eliminated and the accuracy of image quality is considerably improved.However, since the data of the same optical path is averaged, a difference in the value of the sensor pitch remains between adjacent data, so that vertical stripes are also slightly There is a problem that remains.

[0008]

In order to avoid the occurrence of vertical stripes and color unevenness without limiting the front and back sides of the paper sheet, the technique of the above-described conventional example (part 4) is used to narrow the sensor pitch. However, there is a problem that costs are high.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a light transmission data reading apparatus that prevents the occurrence of vertical stripes and color unevenness without reducing the sensor pitch.

[0010]

Means for Solving the Problems 1 is a first light transmission sensor unit, 2 is a second light transmission sensor unit, and a light receiving / emitting unit provided with a light emitting sensor 4 and a light receiving sensor 5 in substantially the same place, respectively.
Numerals 3 are linearly arranged at a predetermined pitch, and are arranged so as to be shifted from each other by a half pitch in the arrangement direction of the light receiving / emitting sections 3.

Reference numeral 14 denotes a light transmission data processing unit, which is a light emission sensor of the first light transmission sensor unit 1 and the second light transmission sensor unit 2.
4 sequentially emits light, and the light receiving sensors on both sides separated by a half pitch from a position facing the light emitting sensor 4 that emitted the light.
Causes received by the light receiving sensor 5 of a predetermined side of the five, each of the first light transmission sensor and the second light transmission sensor
From the light transmission data received by the light receiving and emitting unit, the average value of the light transmission data of the adjacent and opposite light paths is calculated.
In this case, light transmission data at each light receiving / emitting unit is used.

[0012]

The first light transmission sensor section 1 and the second light transmission sensor section 2 are opposed to each other with the light receiving / emitting sections 3 being shifted by 1/2 pitch. The light transmission data processing unit 14 sequentially emits light from the light-emitting sensors 4 to irradiate light from both sides of the paper sheet 20 and receives light from one of the light-receiving sensors 5 on both sides facing the light-emitting sensor 4. 5. As shown in FIG. 1, for example, the transmitted light is received by the upper left and lower left light receiving sensors 5, respectively. The received light transmission data (D1, D
2, D3...), The average value of the light transmission data (D1 and D2, D2 and D3,...) Of the adjacent and opposite optical paths is calculated and used as the light transmission data at that position.

By arranging the sensor (light receiving / emitting section 3) in such a manner that the positional relationship of the sensor (light receiving / emitting section 3) is shifted by a half pitch and irradiating the paper sheet 20 from both sides, the same light emitting sensor as the conventional example (part 4) is obtained. The number of light paths is twice as many as the number of light-receiving sensors (in FIG. 1, the conventional method is ○, the present invention is ＋+ ×), that is, the resolution is doubled, and the average value of the adjacent light paths is used. Is corrected, and variations in light transmission data, color unevenness, and vertical stripes are corrected.

As other average values, there are an average value of the same optical path (the resolution is twice that of the conventional optical path) and two sets of adjacent optical paths in the opposite direction.

[0015]

FIG. 2 is a flowchart of the process, and FIG. 3 is a block diagram of one embodiment. 3, reference numeral 1 denotes a first light transmission sensor, which corresponds to the upper light transmission sensor 21 in FIG.
Reference numeral 2 denotes a second light transmission sensor, which corresponds to the lower light transmission sensor 22. Reference numeral 10 denotes a driver, which is composed of registers and the like for the number of light-emitting sensors, and drives the light-emitting sensors 4 sequentially. A switching circuit 11 selects a light receiving sensor 5 corresponding to each light emitting sensor 4 and inputs light transmission data (analog amount).
Reference numeral 12 denotes an amplifier circuit, which amplifies the light transmission data of each light receiving sensor 5 output from the switching circuit 11. Reference numeral 13 denotes an A / D conversion circuit for digitally converting the amplified light transmission data.
Reference numeral 14 denotes a light transmission data processing unit which performs drive control and switching control of the light emission sensor to acquire light transmission data, calculates an average value described later, and stores the calculated average value in the storage unit 16. In addition, 15 is a central processing unit, 16 is a storage unit, 17 is a buffer, and 18 is an entry sensor for detecting entry of the paper sheet 20.

The first light transmission sensor unit 1 and the second light transmission sensor unit 2 are arranged such that a light emitting / receiving unit 3 in which a light emitting sensor 4 and a light receiving sensor 5 are arranged at substantially the same location is arranged at a predetermined pitch (sensor pitch). They are arranged one-dimensionally, and are arranged facing each other with a shift of 1/2 of the sensor pitch. The positional relationship between the light-emitting sensor 4 and the light-receiving sensor 5 is arranged in the arrangement direction in FIG. 1, but is actually arranged at right angles to the arrangement direction, that is, in parallel with the transport direction of the paper sheet 20. I have.

There are two sets of light transmission data of adjacent and opposite optical paths for each light receiving / emitting unit 3, but here, FIG.
Only one set of the directions shown in FIG. Therefore, the corresponding light receiving sensor 5 is determined for each light emitting sensor 4, and the light transmitting sensor is switched to the corresponding light receiving sensor 5 while scanning driving the light emitting sensor 4 so as to read the light transmission data.

In the above configuration, the following read operation is performed. The reference light transmission data processing unit 14 shown in FIG. 2 sequentially scans and drives all the light emission sensors 4 of the first light transmission sensor unit 1 and the second light transmission sensor unit 2. At the same time, the switching circuit is switched to the predetermined light receiving sensor 5 according to the drive of the light emitting sensor 4.
11 is switched sequentially. As a result, the light transmission data from each light receiving sensor 5 is amplified by the amplifier circuit 12, and the A / D conversion circuit
At 13 it is converted to a digital quantity.

The light transmission data processing unit 14 stores the A / D converted data in a buffer 17 and calculates an average value when two sets of light transmission data of adjacent and opposite optical paths are obtained. Stored in the storage unit 16.

In the above processing, the light transmission data of the entire surface of the paper sheet is sampled by the transport of the paper sheet 20, and the data is obtained in the storage unit 16. As described above, by shifting the sensor pitch between the first light transmission sensor unit 1 and the second light transmission sensor unit 2 by half, the number of optical paths is doubled as compared with the related art, By taking the average of the adjacent and reverse optical paths, the difference in the value between the adjacent light paths is corrected, and the occurrence of color unevenness and vertical stripes is eliminated.

[0021]

According to the present invention, the optical path is doubled by shifting the upper and lower sensor pitches by a half pitch, and by taking the average value of the adjacent optical paths in the opposite direction, the color unevenness is reduced.
Since vertical stripes are corrected, there is an effect that high-quality light transmission data can be obtained.

[Brief description of the drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a processing flowchart.

FIG. 3 is a configuration diagram of one embodiment.

FIG. 4 is an explanatory diagram of reading of light transmission data.

FIG. 5 is a diagram showing a conventional example (part 1).

FIG. 6 is a diagram showing a conventional example (part 2).

FIG. 7 is a diagram showing a conventional example (part 3).

FIG. 8 is a diagram showing a conventional example (part 4).

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 first light transmission sensor unit 2 second light transmission sensor unit 3 light receiving / emitting unit 4 light emitting sensor 5 light receiving sensor 10 driver 11 switching circuit 12 amplifying circuit 13 A / D conversion circuit 14 light transmission data processing unit 15 central processing unit CPU 16 storage unit 17 buffer 18 rush sensor 20 paper sheet 21 upper light transmission sensor unit 22 lower light transmission sensor unit

Claims (1)

(57) [Claims] A first light transmission sensor and a second light transmission sensor;
The paper sheets are conveyed between the two light transmitting sensors.
The sheet is irradiated and received from both sides by the
An optical transmission data reader <br/> reading light transmission data of the paper sheet, a plurality of which includes a light emitting sensor and a light receiving sensor at substantially the same location
The light receiving / emitting section is at a predetermined pitch and is perpendicular to the transport direction of the sheet.
The first light transmission sensor section linearly arranged in the direction
And a light emitting / receiving section having the same structure as the first light transmission sensor section.
The first light transmission sensor unit
The optical parts are arranged facing each other with a shift of one half of the predetermined pitch
Receiving the second light transmission sensor unit and the first light transmission sensor unit and the second light transmission sensor unit.
The light-emitting sensor of the light-emitting unit emits light sequentially and faces each light-receiving and light-emitting unit.
On both sides that are one-half pitch apart from the position
Each of the light receiving sensors of the light receiving and emitting part on the predetermined side of the light part
Receives light and transmits the received light at each light receiving and emitting unit.
Of the data, the light transmission data of the adjacent and opposite optical paths
Of the paper sheet and calculate the average value of
And a light transmission data processing unit that performs
Light transmission data reader.