Mail processing machine and method of sorting mails.

BACKGROUND OF THE INVENTION

Field of the Invention

0001The present invention relates to a mail processing machine (face-canceller) which can arrange mails, cancell postage stamps and sort the mails according to mails whose address is written in print or mails whose address is written in handwriting.

0002The mails sorted as that the address characters are written in print are further sorted with respect to Zip codes by a Zip code reader, while the mails sorted as that the address characters are written in handwriting are further sorted with respect to Zip codes by human labor.

Description of the Prior Art

0003There exist mail processing machines for facing mails, discriminating whether the characters are written in print or in handwriting, cancelling stamps, and sorting the mail according to printed mails and handwritten mails. In these prior-art mail processing machine, however, since the two entire surfaces of a mail are scanned by two optical character readers (OCRs) to discriminate printed mails from handwritten mails or vice versa, there exist some problems in that the cost of the OCRs is high and the processing time is relatively long. This is because when the front surface or the back surface of a mail is not determined because of the absence of a postage stamp, the mail characters must be read and discriminated on both the surfaces of the mail.

0004With these problems in mind, therefore, it is the primary object of the present invention to provide a mail processing machine provided with a single recognizer (OCR).

0005To achieve the above-mentioned object, a mail processing machine according to the present invention comprises: (a) feeding means for feeding mails having first and second surfaces one by one; (b) first detecting means for detecting mail address information written on a first surface of a mail; (c) second detecting means for detecting mail address information written on a second surface of the mail; (d) determining means, coupled to said first and second detecting means, for determining a front surface of the mail on which mail address characters are written on the basis of the detected mail address information; (e) third detecting means for detecting mail address character images on the first surface of the mail, when said determining means determines that mail address characters are written on the first surface of the mail; (f) fourth detecting means for detecting mail address character images on the second surface of the mail, when said determining means determines that mail address characters are written on the second surface of the mail; and (g) recognizing means, for recognizing features of mail address character images, said recognizing means being connected to said third detecting means when said determining means determines that the mail address characters are written on the first surface of the mail and to said fourth detecting means when said determining means determines that the mail address characters are written on the second surface of the mail.

0006The above mail surface information is a mail address window, label, and the quantity of characters.

0007In the mail processing machine of the present invention, in order to minimize the quantity of mail surface image signals to be recognized by the recognizing mean, (1) the front of a mail on which a mail address is written is determined by the presence of a postage stamp, and an address window/label. Further, in the case where no postage stamp and no address window/label are present, the mail front is determined by comparing the character areas of both surfaces of the mail (in usual, many characters are written on the front of a mail); (2) an address character position is detected on the basis of a mail address window and/or label. Further, in the case where no address window/label is present, surface image signals finely scanned on a mail front are once compressed and then binarized to determined an address character area; and (3) surface image signals corresponding to only the detected address window/label or the determined address character area are recognized to determine whether address characters are printed or handwritten.

0008In other words, the operation load applied to the recognizer can be minimized by previously detecting a mail front and an address character position or area. Since only a single recognizer is incorporated in the mail processing machine of the present invention, the mail processing speed is high and the machine cost is low as compared with the prior-art machine.

BRIEF DESCRIPTION OF THE DRAWINGS

0009The features and advantages of the mail processing machine according to the present invention will be more clearly appreciated from the following description of the preferred embodiment of the invention taken in conjunction with the accompanying drawings in which like reference numerals designate the same or similar elements or sections throughout the figures thereof and in which: <ul id="ul0001" list-style="none"><li>Fig. 1 is an illustration for assistance in explaining four situations of mail fed through the mail processing machine;</li><li>Fig. 2A is a diagrammatical view showing an embodiment of the mail processing machine according to the present invention;</li><li>Fig. 2B is a block diagram showing the mail processing machine of the present invention shown in Fig. 2A;</li><li>Fig. 3A is a block diagram showing an address position detector shown in Fig. 2;</li><li>Fig. 3B is a graphical representation showing signal level of surface information detected by the address position detector shown in Fig. 2;</li><li>Fig. 4 is a block diagram showing character detectors and a recognizer both shown in Fig. 2; and</li><li>Fig. 5 is a block diagram showing an address position detector shown in Fig. 4.</li></ul>

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

0010An embodiment of the mail address processing machine according to the present invention will be described hereinbelow with reference to the attached drawings.

0011In Fig. 2A, the mail processing machine reads a Zip code and an address written on a mail, discriminates whether the address characters are written in print or in handwriting, cancels stamps, and sorts the mail into two groups of printed address mails and handwritten address mails. A first group of mails sorted as print writing is further sorted automatically by a Zip code reader; while a second group of mails sorted as handwriting is further sorted by manual operation according to Zip codes.

0012The mail processing machine shown in Figs. 2A and 2B comprises an operator panel 101, a controller 100, a mail box 1, a mail carrier 1A, two stamp detectors 3a and 3b, a non-inversion path 5 and an inversion path 7 (mail arrangement mechanism), two stamp detectors 9a and 9b, two address position detectors 20a and 20b, a branch mechanism 50, two character detectors 30a and 30b, a recognizer 40, two stamp cancellers 13a and 13b, and a sorter 15 including plural mail sorting boxes 15a to 15e.

0013In more detail with reference to Fig. 2A, a lot of mails are arranged in a mail box 1. Each mail arranged in the mail box 1 is fed one by one to two (postage) stamp detectors 3a and 3b in vertical mail position. In this case, when a postage stamp is attached to a corner of a mail as shown by (a) in Fig. 1, four different positions (a), (b), (<img file="EP0281007A2_D0001.tif" />) and (<img file="EP0281007A2_D0002.tif" />) can be considered as depicted in Fig. 1, in which solid lines of a stamp indicate that a stamp is attached on the front surface side of a mail and dashed lines thereof indicate that a stamp is attached on the back surface side of a mail. Here, the two stamp detectors 3a and 3b are so arranged as to detect the stamp only when the stamp is located at the lower ends of the mail as depicted by (a) and (b) in Fig. 1, respectively. That is, the stamp attached as (a) in Fig. 1 can be detected by the stamp detector 3a, and that attached as (b) in Fig. 1 can be detected by the stamp detector 3b. When these two detectors 3a and 3b detects the presence of a stamp, the mail is fed through a non-inversion path 5. However, when these two detectors 3a and 3b cannot detect the presence of a stamp or when the stamp is located at the upper ends of the mail as depicted by (<img file="EP0281007A2_D0003.tif" />) and (<img file="EP0281007A2_D0004.tif" />) in Fig. 1, respectively, the mail is fed through an inversion path 7 to reverse the mail upside down so that the mail is always located as shown by (a) and (b) in Fig. 1. In more detail, when the stamp is located as (<img file="EP0281007A2_D0005.tif" />) and reversed, the stamp is located as (a); when stamp is located as (<img file="EP0281007A2_D0006.tif" />) and reversed, the stamp is located as (b) in Fig. 1.

0014The mail so arranged that the stamp is located on the lower side thereof is then fed to the next two stamp detectors 9a and 9b to detect the presence or absence of the stamp. Therefore, when the stamp detector 9a or 9b detects the presence of stamp, it is possible to determine that the address is written on the side on which at least one stamp is stuck.

0015The address position detector 20a or 20b detects the address character position and the front surface of a mail on which an address is written on the basis of mail surface information. That is, when the presence of stamp is detected by the stamp detector 9a or 9b, the address position detector 20a or 20b next detects the presence of an address window covered by cellophane or an address label on which an address is written in order to detect a mail address character position. When the presence of stamp is not detected by the two stamp detectors 9a and 9b. The quantity of characters or the extent of characters written on one surface of the mail is compared with that on the other surface of the same mail by the two address position detectors 20a and 20b in order to determine the front surface or the back surface of the mail. That is, the surface on which many characters are written is determined as the front surface of the mail.

0016On the basis of the above detected window or label position and the quantity of characters, it is possible to detect the front side or the back side of the mail and the address position or area where an address is written. In other words, even when the stamp detector 9a or 9b cannot detect the presence of a postage stamp, the front surface of the mail is determined on the basis of the address window, the address label, or the quantity of characters detected by the address position detector 20a or 20b. The quantity of the address characters can be determining by integrating the image signals indicative of address characters.

0017When the address position detector 20a detects the front of a mail, the branch mechanism 50 is actuated so that the mail is fed to the character detector 30a. On the other hand, when the address position detector 20b detects the front of a mail, the branch mechanism 50 is actuated so that the mail is fed to the character detector 30b.

0018In more detail, with reference to Fig. 3A, the address position detector 20a or 20b comprises a light source 21 for emitting a light beam toward a mail fed through a carrying path for scanning, a lens 22 for focusing the light reflected from the mail, a photosensitive element 23 composed of a line image sensor (e.g. charge coupled devices) for detecting characters written on the mail, an amplifier 24 for amplifying the detected character image signal S, and two quantization circuits 25A and 25B. The light source 21 and the lens 22 are both disposed relative to the mail in such a way the an incidence angle α is roughly equal to a reflection angle β. The quantization circuit 25A compares the image signal S detected by the photosensitive element 23 with a slice level B outputted from a controller (not shown), and outputs a window/label signal (W/L SIG) indicative of the presence of a window or label of a high reflectivity, when the level of the image signal S exceeds the slice level B as shown by S_C in Fig. 3B. On the other hand, the quantization circuit 25B compares the image signal S with a slice level C also outputted from a controller (not shown) and output a paper surface signal S_B indicative of the absence of characters of a middle reflectivity, when the level of the image signal S lies between the slice levels B and C. Further, when the two quantization circuits 25A and 25B generate no quantized signal, the signal S_d is determined as a character signal (CHR SIG) indicative of the presence of characters of a low reflectivity. Further, in Fig. 3B, the level A of the image signal S is detected when the mail surface is deep black.

0019In the address position detector 20a or 20b, the resolving power of scanning is not high (e.g. a single scanning line per millimeter) because this detector detects only the position of an address window/label. The window/label position can be detected in the form of (x, y) coordinates indicative of the number of the horizontal scanning line from an upper edge and a time period from an edge of the horizontal scanning line, for instance.

0020When no postage stamp and no address window/label detected, the character signal S_d outputted from the quantization circuit 25B is integrated by an integrator 26 and supplied to a comparator 27. On the other hand, other character signal S_dʹ outputted from another quantization circuit 25Bʹ of the address position detector 20b is integrated by an integrator 26ʹ and supplied to the comparator 27. The comparator 27 compares these two integrated character signals to determine the front side of a mail. For instance, if the character signals integrated by the integrator 26 is large, the comparator 27 generates a command signal to the branch mechanism 50 to feed the mail toward the character detector 30a. In response to this command signal, character detector 30a is activated to detect the character images.

0021Fig. 4 shows the two character detectors 30a and 30b and the recognizer 40. Each character detector 30a or 30b comprises a fine scanner 31a or 31b and a quantization circuit 32a or 32b. The fine scanner 31a or 31b generates image signals in almost the same way as in the address position detector 20a or 20b by irradiating the mail surface with a light beam and transducing the reflected light beam by photosensitive elements into image signals. However, the resolving power of the fine scanner 31a or 31b is as high as 8 lines per millimeter because this detector detects the features of characters.

0022The quantization circuit 32a or 32b compares the detected mail surface image signals with a predetermined slice level and outputs character image signals only when the image signal drops below a slice level (the above processing being referred to as binarization).

0023The recognizer 40 comprises an image memory 41, an address position detector 42, a line detector 43, a parameter extractor 44, and a discriminator 45.

0024The image memory 41 stores all the scanned and binarized character image signals detected by either one of the character detector 30a or 30b. This is because the front surface of a mail has already been detected by the address position detectors 20a and 20b, and the detected mail is fed to any one of the character detectors 30a and 30b. Therefore, the image memory 41 stores the character image signals corresponding to the detected front surface of a mail and detected by any one of the character detectors 30a and 30b.

0025The character tline detector 43 functions as follows: The preceding processings have already detected an address position or area where an address is written. Therefore, in this step, character lines are further detected from the detected address area. That is, since an area where characters are gathered has already been determined, the succeeding step determines how the characters are arranged within the detected address area.

0026For doing this, the number of character image signals are counted along the direction perpendicular to the character lines in order to obtain a histogram. By detecting the peaks of the histogram indicative of the distribution of the character image signals, it is possible to detect the number of lines. As to the above-mentioned character line detection, if should be nothed that the scanning operation is as fine as 8 lines per millimeter, for instance, as compared with the coarse scanning operation (e.g. 1 line per millimeter) of the address position detector 20a or 20b.

0027The parameter extractor 44 detects character feature parameters. These parameters are dispersions of various character features such as (1) character height; (2) character lower edge position; (3) character width; (4) character pitch; (5) character area; (6) line arrangement slope; (7) leftmost character position; (8) line space, etc.

0028To obtain character feature parameters, a reference threshold value δ₀² of each of the dispersions of the character features is previously determined. Each actual dispersion value δ² obtained by calculating image signals read from the image memory 41 is compared with this reference threshold value δ₀². The compared result (the difference between the actual dispersion and the reference dispersion) is stored in the image memory 41 and added in sequence to obtain a sum total of the differences between the two of the above-mentioned eight character features. When the discriminator 45 determines that the sum total of the dispersion differences between the actual values and the reference values exceeds a predetermined value, the characters are discriminated as a handwritten mail. In contrast with this, when the discriminator 45 determines that the sum total of the dispersion differences is less than the predetermined value, the characters are discriminated as a printed mail.

0029Fig. 5 is a block diagram showing the address position detector 42, which comprises a W/L signal detector 421, a compressor 422, an address area detector 423 and an image data reader 444.

0030When the W/L signal detector 421 detects a presence of W/L signal indicative of a window/label position (x-y coordinates), the image data reader 444 reads image data corresponding to only the window/label position from the image memory 41.

0031When the W/L signal detector 421 detects an absence of W/L signal, the compressor 422 reads the entire image signals from the image memory 41 for compression. For instance, the resolving power of the image signals is reduced from 8 lines per mm to 1 line per mm by simply averaging the eight horizontal scanning line signal levels. The address area detector 423 compares averaged signal levels with a slice level for binarization, and determines an address character area on the basis of the binalized character image signals collected at an area on the front surface of a mail. When this address character area has been detected, the image data reader 444 reads image data corresponding to only the determined address character area.

0032When the stamp detector 9a or 9b detects the presence of a postage stamp on the mail, a stamp canceller 13a or 13b corresponding to the stamp detector 9a and 9b impresses a mark on the detected postage stamp. The mails thus detected are sorted and put into five sorting boxes 15a to 15e, in such a way that mails having an address written in print and detected by the character detector 30a are arranged in the box 15a; mails having an address written in handwriting and detected by the character detector 30a are arranged in the box 15b; mails having an address written in print and detected by the character detector 30b are arranged in the box 15c; mails having an address written in handwriting and detected by the character detector 30b are arranged in the box 15d; and other mails determined to be rejected are arranged in the box 15e.

0033In the prior-art machine, when no stamp is detected, it is necessary to entirely scan both the surfaces of the mail by two optical character readers. Further, even if a stamp is detected, it is necessary to scan the entire surface of the front of the mail, so that the mail processing speed is relatively low. In the machine of the present invention, it should be noted that since the address position detector 20a or 20b can detect a window/label position and the front side of the mail (by comparing the quantity of characters) and further the address position detector 42 can determine an address character area, character images corresponding to only the front surface of the mail and only the address position (window or label) or address character area can be read from the image memory 41 for discrimination. Therefore, character image data to be discriminated are not huge, so that it is possible to increase the mail processing speed and therefore decrease the cost of the machine by providing only a single recognizer 40 including the discriminator 45.

0034The operation of the mail processing machine of the present invention will be described hereinbelow.

0035The mails are arranged in the mail box 1 and fed one by one to the stamp detectors 3a and 3b via a path 1A in a vertically arranged position. When the stamp detector 3a or 3b detects the presence of a stamp attached to the lower side end of the mail, for instance, the mail is fed through the non-inversion path 5. When the stamp detector 3a or 3b detects the absence of a stamp, the mail is fed through the inversion path 7. Thereafter, the stamp detector 9a or 9b detects the presence or absence of a stamp on the mail. When the presence of the stamp is detected, this stamp presence signal is applied to the stamper 13a or 13b to impress a mark on the stamp of the mail just before sorting the mails.

0036When no stamp is detected by the two stamp detectors 9a and 9b, the front side of the mail (on which an address is written) is detected by the two addresses position detectors 20a and 20b. That is, the surface on which many characters are written is determined as the front side surface of the mail.

0037The address position (surface information) detector 20a or 20b also detects the position of a window or a label. In this process, when the address position detector 20a detects a mail front, the branch mechanism 50 is actuated so that the mail is fed to the character detector 30a; and when the address position detector 20b detects a mail front, the branch mechanism 50 is actuated so that the mail is fed to the character detector 30b.

0038Since the front surface of a mail has already been detected by the address position detectors 20a and 20b and the detected mail is fed to any one of the character detectors 30a and 30b. The character detector 30a or 30b detects characters on the front surface of a mail by scanning and quantization. The detected character image signals detected by the character detector 30a or 30b are stored in the image memory 41. Further, only the character image signals corresponding to the address position signals (window/label signal) are read from the image memory 41 by the address position detector 42 on the basis of the window/label signal detected by the address position detector 20a or 20b.

0039The character features (e.g. arrangement order, regularity, size, density, etc.) of the read character image signals are detected by the parameter extractor 44 and discriminated as to printed mail or handwritten mail by comparing the extracted character futures with the stored reference character values by the discriminator 45.

0040Further, where no window/label signal is detected, the address position detector 42 itself determines an address character area by compressing the entire surface image signals and binarizing the compressed signals. When a character area signal is detected, only the character image signals corresponding to the address area signal are read from the image memory 41 for discrimination.

0041The mails thus discriminated are stored into the five sorting boxes 15a to 15e.

0042In the above description, the mail processing machine of the present invention has been disclosed with reference to block diagrams (i.e. hardware configuration). In practice, however, the mail processing machine is controlled by the controller 100 provided with a ROM, a ROM, a display unit, a keyboard 101, etc., which is operated in accordance with control programs (i.e. software).

0043As described above, in the mail processing machine of the present invention, since the surface information (window or label position, quantity of characters, character block position is first detected and then only the character image signals limited by the surface information are discriminated as to whether the address characters are written in print or handwriting, it is possible to improve the sorting speed of the mail, while reducing the cost of the machine.