JPS6244672B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical character reading device for optically reading a postal code from a transported mailpiece, for example in an automatic postal code reading and sorting machine.

In general, this type of optical character reading device conveys a mail piece with a postal code written on it, and uses an imager to optically read and scan the transported mail piece to read the postal code. I'm learning to read. A self-scanning CCD image sensor having a large number of solid-state image sensors arranged in a straight line is usually used as the image sensor. As such an optical character reading device, for example,
- There is one shown in No. 134994. In this system, first and second reading sections are installed in sequence in the transport direction of the mail item, the first reading section reads and scans the area where the postal code is written, and the position where the postal code is written is determined based on the reading information. By determining this and controlling the movable mirror for setting the reading field position in the second reading section based on the determination result, the second reading section scans in more detail to read the postal code.

However, normally for mail within Japan,
A so-called horizontal postal item P1, in which the postal code 1 (and other destination information 2) is written in the same horizontal direction as the transport direction a, as shown in Figure ₁ , and a postal item as shown in Figure 2. There is a so-called vertical mail item _P2 in which the number 1 is written in the vertical direction perpendicular to the transport direction a. Of these, for horizontally written postal item P ₁ , the installation direction of the image sensor (direction perpendicular to conveyance direction a) is determined from the format of the postal code.
The field of view _H1 may be narrow, and therefore the number of bits of the image sensor may be small. However, in the case of vertically written mail _P2 , the field of view _H2 in the installation direction of the image sensor is required to be wide due to its postal code description format, and the number of bits of the image sensor is therefore increased, resulting in a large capacity. As the number of bits of the image sensor increases in this manner, the scanning frequency of the image sensor increases, and scanning becomes impossible, especially when the conveyance speed of mail increases.

To solve this problem, for example, there is an optical character reading device disclosed in Japanese Patent Application No. 31894/1983. This is achieved by adding a movable mirror for tracking to the second reading section mentioned above, and controlling this movable mirror based on the result of determining the direction in which the postal code is written. Corresponds to W ₁ in the figure and W ₂ in Figure 2)
By tracking only the mail, the transport speed of the mail can be relatively slowed down. According to this, the above-mentioned problems can be improved, but the following new problems have arisen. That is, especially in the horizontally written postal item _P1 , since the dimension of the postal code writing area _W1 in the transport direction a is very long, the illumination range for illuminating the surface of the postal item must also be wide in the transport direction a. This results in drawbacks such as not only increasing the capacity of the light source for bright illumination, but also increasing the size of the illumination optical system including the light source.

The present invention has been made in view of the above circumstances, and its purpose is to narrow the illumination range in the conveying direction of the object to be read, thereby reducing the capacity of the illumination light source and downsizing the illumination optical system. An object of the present invention is to provide an optical character reading device that can be used to read characters.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 3, reference numeral 11 denotes a first reading section, which is provided along the conveying direction a of the mail P (the aforementioned mail P ₁ or P ₂ ) that is conveyed in an upright position.
This first reading unit 11 optically reads and scans the entire field of view on the surface of the mail P and performs photoelectric conversion.
The illumination light source 12 and the condensing lens 13 illuminate the postal item P, and the reflected light is sent to an imager, for example, a CCD image sensor 1, via the imaging lens 14.
5. The image sensor 15 is of a self-scanning type in which a large number of solid-state image sensors are linearly arranged, and is arranged in a direction perpendicular to the transport direction a of the mail P. Thus, the output signal of the image sensor 15 is supplied to the discrimination section 16. Based on the output signal of the image sensor 15, the determining unit 16 determines whether the writing direction of the postal code 1 on the postal item P is horizontal or vertical with respect to the transport direction a, and also determines the writing position of the postal code 1. This is a circuit that also determines the Various methods have been proposed for determining these methods, but to briefly explain a typical example, if there is a separate postage mark (numeral 3 in Figures 1 and 2) on the postal item P, for example, Special request 1977-
As shown in No. 83200, the direction in which the postal code is written is determined by detecting the mark and determining its shape by utilizing the fact that the direction in which the postal code is written corresponds to the shape of the mark. . Alternatively, in the case of a mail item with a window in which the address information area is covered with a transparent material, the direction in which the postal code is written corresponds to the long side of the rectangular window frame, as shown in Japanese Patent Application No. 157546/1983, for example. The window frame is detected, the length of at least one side of the window frame is calculated, and the length of at least one side of the window frame is calculated, and the length is compared with a reference value to determine the direction in which the postal code is written. After determining the writing direction in this manner, the writing position of the postal code is then determined based on the determination result. In other words, since it is generally specified that the postal code is written in the top line of the destination information, the image sensor 1
The destination information is extracted from the reading information on the mail P obtained from step 5, the coordinates of the information present in the top line of the destination information are calculated, and the result is output as a written position determination signal. .

On the other hand, 17 is a second reading section, which is provided in front of the first reading section 11 in the transport direction a of the mail P. The second reading section 17 reads and scans only a set field of view on the surface of the mail P and performs photoelectric conversion, and is configured as follows. That is, the illumination source 18 and the condensing lens 19 illuminate the mail P, and the reflected light is guided to the first movable mirror (for example, a galvanic mirror) 20 for switching the optical path and setting the reading field position. It's summery. The first movable mirror 20 rotates according to the output signal of the discriminator 16 when its drive section 21 is supplied with the output signal of the discriminator 16, so that the first movable mirror 20 rotates the reflected light from the postal item P along the optical path l ₁ Alternatively, it leads to _l2 , and also sets the reading field position on the mail P in the direction perpendicular to the transport direction thereof. Therefore, the reflected light guided to the one optical path _l1 is reflected by the mirror 22,
The image is formed through an imaging lens 23 on a first imager for horizontally written mail, for example, a CCD image sensor 24 . The first image sensor 24 is similar to the image sensor 15, and is disposed in a direction perpendicular to the conveyance direction a of the mail P, and its bit number is equal to the horizontal writing mail shown in FIG. It corresponds to the visual field H ₁ of the object P ₁ . Further, the reflected light guided to the other optical path _l2 is reflected by a second movable mirror (for example, a galvanic mirror) 25 for tracking.
, and is imaged through an imaging lens 26 on a second image pickup device for vertically written mail, for example, a CCD image sensor 27 . The second movable mirror 25 rotates in response to the output signal of the discriminator 16 supplied to its drive unit 28, and conveys the reading field of view set by the first movable mirror 20. It follows in the same direction as direction a. Further, the second image sensor 27
is similar to the image sensor 15, and is arranged in a direction perpendicular to the transport direction a of the mail P, and its number of bits is equal to that of the vertical mail shown in FIG.
It corresponds to the field of view H ₂ of P ₂ . Thus, each output signal of the first and second image sensors 24 and 27 is supplied to a selection circuit 29. This selection circuit 29 selects the output signal of the first image sensor 24 or the output signal of the second image sensor 27 based on the output signal of the discrimination section 16, and supplies it to the character recognition section 30.

Next, the operation in such a configuration will be explained. When the mail P being conveyed now corresponds to the first reading section 11, the top of the mail P is illuminated by the illumination light source 12 and the condensing lens 13, and the reflected light is converted into an image via the imaging lens 14. An image is formed on the sensor 15. Therefore, the image sensor 15 reads and scans the entire field of view on the mail P by self-scanning, and supplies the photoelectric conversion signal to the discrimination section 16. As described above, the determination unit 16 determines the writing direction and writing position of the postal code 1 on the mail P based on the output signal of the image sensor 15. For example, if the postal item P being conveyed now is a horizontally written postal item _P1 shown in FIG. 2 First movable mirror 2 in reading section 17
0 to the drive section 21 and the selection circuit 29, and at the same time, the position where postal code 1 is written is also determined and the discrimination signal is supplied to the drive section 21.
As a result, the first movable mirror 20 rotates and
It is set so that the reflected light from _P1 passes through the optical path _l1 , and the reading field is set according to the result of the written position determination. In this way, in this case, the transport direction a
Since the field of view W ₁ is wide, the second movable mirror 25 is not used, and the first movable mirror 20 selects the optical path l ₁ . Therefore, the reflected light from the mail _P1 is transmitted to the first image sensor 24 by the first movable mirror 20, the mirror 22, and the imaging lens 23.
is imaged. In the case of this horizontally written postal item _P1 , the field of view _H1 perpendicular to the transport direction a is narrow, so the number of bits of the first image sensor 24 is also small. For this reason,
Even if the second movable mirror 25 does not follow the mail P ₁ and relatively reduce the conveyance speed, the scanning frequency of the first image sensor 24 can be made sufficiently low. Character information signals can be extracted. Therefore, in this case,
Since the viewing range _H1 perpendicular to the transport direction a is narrow,
Despite the wide viewing range W ₁ in the transport direction a, there is no need for a movable mirror to follow the movement, and the illumination range of the mail P ₁ in the transport direction a can be significantly narrowed, allowing for a small capacity illumination light source. This makes it possible to downsize the illumination optical system.

On the other hand, if the mail P to be conveyed is a vertically written mail _P2 shown in FIG.
It is determined that the direction in which the postal code 1 is written is vertical, and the determination signal is supplied to the drive unit 21 of the first movable mirror 20 and the selection circuit 29, respectively.At the same time, the position in which the postal code 1 is written is also determined and the determination signal is sent. It is supplied to the drive section 21. In this case, the determination unit 16
supplies a follow-up control signal to the drive section 28 of the second movable mirror 25. As a result, the first movable mirror 20 is rotated so that the reflected light from the postal item _P2 passes through the optical path _l2 , and the reading field is set in accordance with the result of the written position determination. Further, the second movable mirror 25 is rotationally controlled in accordance with a control signal from the discrimination section 16. In this way, in this case, the transport direction a
Since the field of view W ₂ is narrow, the first movable mirror 20
The second movable mirror 25 is used to select the optical path _l2 and follow the mail. Therefore, the reflected light from the mail P ₂ is imaged on the second image sensor 27 by the first movable mirror 20 , the second movable mirror 25 and the imaging lens 26 . At this time, the second movable mirror 25 rotates to follow the viewing range _W2 in the transport direction a. In the case of this vertically written mail _P2 , the field of view _H2 perpendicular to the transport direction a is wide, so the number of bits of the second image sensor 27 is also large. Therefore, by following the mail P with the second movable mirror 25 and relatively lowering the transport speed, it is possible to use the second image sensor 27 at a sufficiently low scanning frequency similarly to the first image sensor 24. Therefore, a high quality character information signal can be extracted from the second image sensor 27. Therefore, in this case, since the viewing range H ₂ perpendicular to the transport direction a is wide, a tracking operation is performed using the movable mirror. Even if such a tracking operation is performed, the viewing range W ₂ in the transport direction a is narrow, so the The illumination range in the transport direction a of the object _P2 may be narrow, and it is therefore possible to reduce the capacity of the illumination light source and the illumination optical system.

Therefore, the first and second reading portions in the second reading section 17
Each output signal of the image sensors 24 and 27 is supplied to a selection circuit 29, respectively. The selection circuit 29 is
Since a determination signal indicating whether the writing direction of the postal code is horizontal or vertical is supplied from the determination unit 16, the output signal of the first image sensor 24 or the second image sensor 27 corresponding to the writing direction is is selected and supplied to the character recognition section 30. In the character recognition unit 30, the image sensor 24,
This system extracts only the postal code from the destination information obtained from No. 27, performs character recognition by, for example, a matching method with a well-known reference pattern, and outputs the recognition result. Note that as a means for extracting only the postal code, as mentioned above, the postal code is normally written in the top line of the destination information, so the destination information obtained from the image sensors 24 and 27 is used. By detecting the character information present in the top line, only the postal code can be easily extracted.

As described in detail above, according to the present invention, it is determined whether the writing direction of character information on the object to be read is horizontal or vertical based on the reading information obtained from the first reading unit, and at the same time, the writing position of the character information is determined. By controlling the first and second movable mirrors provided in the second reading unit based on the result of this determination,
A movable mirror selectively guides the reflected light from the object to be read to a first imager for the horizontal direction or a second imager for the vertical direction, and also sets the reading field of view position. In the case of the direction, since the second movable mirror is configured to follow the reading field of view, the illumination range in the direction of conveyance of the object to be read can be narrowed regardless of the direction in which the character information is written.
As a result, it is possible to provide an optical character reading device that provides various effects such as a smaller capacity illumination light source and a smaller illumination optical system.

[Brief explanation of the drawing]

1 and 2 are diagrams showing an example of an object to be read, and FIG. 3 is a schematic diagram showing an embodiment of the present invention. P ₁ ...Horizontal mail, P ₂ ...Vertical mail, 1...
Postal code, P... Mail, 11... 1st reading section,
16... Discrimination section, 17... Second reading section, 18...
Illumination light source, 20... First movable mirror, 24...
First imager, 25... Second movable mirror, 27...
Second image pickup device, 29... selection circuit, 30... character recognition unit.

Claims (1)

[Claims] 1. A first reading section that optically reads and scans the object to be read that is being conveyed, and an output signal from this first reading section that allows the writing direction of character information on the object to be read to be aligned with respect to the direction of conveyance of the object to be read. A discrimination unit that discriminates whether the orientation is horizontal or vertical and also discriminates the position where the character information is written; a light source that illuminates the object to be read being conveyed; and a discrimination section that determines the light reflected from the object to be read by the light source a first movable mirror that selectively guides the light in two directions based on the determination result of the object and sets the reading field position in a direction perpendicular to the conveying direction of the object to be read; A second movable mirror that follows the reading field set by the first movable mirror in the same direction as the conveyance direction of the object to be read, and a first image pickup that receives the other reflected light from the first movable mirror and converts it into an electrical signal. and a second image pickup device that receives reflected light from the second movable mirror and converts it into an electrical signal, and is provided in front of the first object in the conveying direction of the object to be read. An optical character reading device, characterized in that the reading signal corresponding to the writing direction of character information is obtained from the first and second image pickup devices.