JPS60156189A - Optical character and mark reading method - Google Patents

Abstract

PURPOSE:To attain uniform and accurate reading of a character/mark displayed on both sides independently of the difference of transmissivity of a medium by detecting optically a reference mark or a character from the reading side. CONSTITUTION:A clear signal 17 is inputted to the 2nd register 15 of a peak value detecting section 8 from a system control section 12 at first so as to clear the recorded content of the 2nd register 15. Then the reference mark 1C is searched over the range of X1 by a reading head of a photoelectric converting section 6 while a document 1 is carried by Y1 in the carrying direction. An analog signal as a result of searching is converted digitally and stored by one picture element each in the 1st register 13 at the leading of a write clock 19. A multi-valve data representing the stored picture level is inputted to an input terminal A of a comparator 14. The repetition of the operation above, that is the data rewrite in the 2nd register 15 by the comparator 14 is conducted over the entire region of the reference mark 1C.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to optical characters and marks displayed on both the front and back sides of paper or other media having a certain light transmittance, which can be read from one side at a time.・Regarding how to read marks.

[Technical Background of the Invention] Conventionally, optical character/mark reading devices (hereinafter referred to as OCR) have been used to read characters/marks displayed on both sides of paper or other media having a certain degree of light transparency, such as the front and back of a form. There is a known method for reading from one side at a time.

In this method, a form with characters and marks to be identified on both sides is conveyed one by one on a guide surface that is painted white to have high light reflectance. The reflected light on the front surface and the light that passes through the form, is reflected on the back surface and the guide surface, and passes through the form again are incident on a reading head such as a photoelectric conversion element. The light incident on the reading head is photoelectrically converted into an analog signal, and this analog signal is further converted into a digital signal and binarized using a preset slice value (binarization reference level). Mark discrimination is performed.

[Problems with the Background Art] However, in the conventional optical character/mark reading method as described above, the slice value used to binarize the signal from the reading head is preset as a fixed value. When reading the characters and marks on the back side, especially if the form is thicker than the standard and has poor light transparency, some of the characters and marks on the back side may be missing.
On the other hand, if the form is thinner than the standard and its light transmittance is too good, there is a problem in that the lines will be read as thick.

Therefore, the light intensity of the light source is increased depending on the light transmittance of the form, and the reading sensitivity, that is, the slice value is changed between the front side and the back side. However, the thickness of the form to be read is It is difficult to accurately adjust the reading sensitivity in cases where the reading sensitivity is different from each other.

[Object of the Invention] The present invention has been made to solve these conventional difficulties, and allows characters and marks displayed on both the front and back sides of paper or other media with a certain degree of light transmission to be read from one side. The purpose of the present invention is to provide an optical character/mark reading method that can uniformly and accurately read characters/marks displayed on both sides, regardless of the difference in light transmittance of the medium, when reading at one time. .

[Summary of the Invention] In other words, the optical character/mark reading method of the present invention is a method of reading characters/marks recorded on both the front and back sides of paper or other medium having a certain light transmittance from one side at a time. A reference mark or character is recorded at a predetermined position on the surface of the medium opposite to the reading side, and upon reading, the reference mark or character is optically detected from the reading side, and the detected reference mark or character is optically detected from the reading side. The present invention is characterized in that a slice value for binarizing the read signal in back side reading is determined based on the black peak value of the reference mark or character.

[Embodiment of the Invention] The details of the present invention will be described below with reference to an embodiment shown in the drawings.

FIG. 1 is a side view schematically showing a form and OCR used in this embodiment.

In the figure, reference numeral 1 indicates a form on which characters/marks IA and IB to be read are recorded on the front and back sides, respectively.

A plurality of forms 1 are stored in a hopper (not shown),
The form is sent out one by one from the hopper by the form sending mechanism,
The paper is conveyed in the direction of arrow P on a conveyance path 2 whose upper surface is painted in a bright color such as white to increase light reflectivity.

On the conveyance path 2, a light source 3, a reading head 4, and a leading edge detection cell 5 for detecting the leading edge of the form 1 in the conveying direction are arranged.

In this OCR, part of the light emitted from the light source 3 is reflected by the surface of the form 1, and the remaining part is reflected by the surface of the form 1.
The light passes through the document 1, is reflected on the back surface thereof and the surface of the conveyance path 2, passes through the document 1 again, and enters the reading head 4, respectively.

The above configuration is similar to the conventional double-sided once reading type OCR.

However, at a predetermined position on the back side of the form 1 used in this embodiment, as shown in FIG. 1c is displayed.

This reference mark 1C is placed vertically (on the form 1
It is displayed in a rectangular area with a length Yl in the direction in which it is transported) and a length in the horizontal direction x 1.

FIG. 3 is a block diagram showing the configuration of the OCR used in this embodiment.

This OCR includes a form sending section 6, a photoelectric conversion section 7 including a reading head that reads incident light as an analog signal, an A/D converter that converts the analog signal into a digital signal, and an output of the photoelectric conversion section 7. a peak value detection section 8 that inputs a signal and detects its peak value, and this peak value detection section 8
The photoelectric conversion unit 7 uses the detected peak value as a slice value.
a binarization unit 9 that binarizes the output signal of the form 1, and the line positions of the front side characters/marks 1A and the back side characters/marks 1B of the form 1;
The format table 10 in which character pitch, font, character type, etc. are registered, and the binary signal output from the binarization section 9 are converted into predetermined characters/marks according to the information registered in the format table 10. A recognition unit 11 that recognizes
Its main part is composed of a system control section 12 that controls the entire system.

Next, the operation of this embodiment will be explained with reference to FIG.

First, when the operator performs an operation to start reading, a predetermined signal is input to the system control section 12, and the system control section 12 supplies a signal for sending the form 1 to the form sending section 9.

Then, when the leading edge of the sent form 1 comes to the position of the leading edge detection cell 5, the leading edge detection cell 5 detects this and a detection signal is input to the system control section 12. The system control unit 12 moves the form 1 from the detection position so that the reference mark 1C of the form 1 is positioned below the reading head 4 according to the line position data written in advance in the format table 10.

Simultaneously with the start of this movement, the system control section 12 activates the peak value detection section 8.

FIG. 4 is a block circuit diagram showing the configuration of the peak value detection section 8 described above.

The peak value detection section 8 includes a first register 13 that latches the information content of the reference mark 1C of the form 1 converted into a digital signal by the photoelectric conversion section 7 described above;
a comparator 14 that compares the respective digital signals input to the reference mark 1C, and a second register 1 that stores the peak value in the digital signal read from the reference mark 1C.
5. In the same figure, reference numeral 16 is a binarization unit that compares the slice value set by the system control unit 12 with the digital signal of each character/mark 1B on the back side read by the photoelectric conversion unit 7 and converts it into a binary value. A comparator forming part 9 is shown.

In the peak value detection section 8, first, the system control section 12
One clear signal 17 is input to the second register 15, and the recorded contents of the second register 15 are cleared.

Next, the reading head of the photoelectric conversion unit 6 searches for the reference mark 1C over a range of x1 while moving the form 1 by Yl in the transport direction.

The searched analog signal is converted into a digital signal 18 by an A/D converter and stored in the first register 13 one pixel at a time at the rising edge of a write clock 19. The stored multivalued data indicating the image level is input as an output signal 20 to the input terminal of the comparator 14.

Here, since the contents of the second register 15 are first cleared, the input value of the input terminal B of the comparator 14 becomes 0'', and as a result, the output of the comparator 14 (A>B) becomes the level ``1''. Since the second register 15 is enabled, the output signal 20 is stored in the second register 15 at the fall of the write clock 19.

Next, at the rising edge of the write clock 19, the next data is supplied from the first register 13 to the A terminal of the comparator 14.
The data being stored from the second register 15 is supplied to the 8 terminals of the comparator 14. At this time, if the data supplied from the first register 13 is larger than the data being stored in the second register 15, The output of the comparator 14 is ``1''1''
The contents of the second register 15 are then rewritten with new data. Conversely, if it is smaller, the output of the comparator 14 is ``0''
" level and no rewriting is performed.

When this operation is repeated, that is, the data in the second register 15 is rewritten by the comparator 14 over the entire area of the reference mark 1C, the black peak in the digital information of the reference mark 1C is finally stored in the second register 15. The value will be stored.

In this way, the black peak value stored in the second register 15 is outputted to the system control unit 12 as an output signal 21, and the slice value when reading the back side character/mark 1B is determined thereby.

If form 1 is thick and has low light transmittance, the black peak value will be small, so the slice value will be set low;
If it is thin and has high light transmittance, the peak value of black will be high, so the slice value is set high.

After setting the slice value, the system control unit 1
2 supplies an instruction signal to the form sending unit 9 to move the form 1 by one line, that is, b-a in FIG.

Then, the slice value set in the system control unit 12 and the back side character/mark 1B read by the reading head 4
The digital signal 18 is compared with the digital signal 18 by the comparator 16 and outputted to the recognition unit 11 as a binary signal 19.

After reading the characters/marks 1B on the back side, the system control unit 1
2 sends the form 1 to the form sending unit 9 from c-b in FIG.
An instruction signal is supplied to move the characters by the characters on the surface.
Mark 1A is read.

Since the surface characters/marks 1A are not affected by the thickness or light transmittance of the form 1, slice values can be set in advance in the system control unit 12 as before, and the digital information read using this slice value can be binarized and read. However, in order to obtain higher reading accuracy, it is desirable to form a reference mark on the front side of the form 1 as well, and to read it using the same process as on the back side.

In the above-described embodiment, the reference mark 1C on the back side of the form 1 was a mark with a density or color corresponding to the text/mark 1B on the back side, but the present invention should not be limited to this embodiment. I at the reference mark 1C position
A field D (I dentification identification label) may be provided in which an ID number is written, and this number 10 may be used as a substitute for the reference mark 1C to set the slice level.

In addition, when processing multiple documents, if the light transmittance of each document is the same, the slice value is determined using the reference mark 1C for only the first document, and this slice value is used for the subsequent The processing speed can be improved by binarizing the characters and marks on the back side of the form.

[Effect of the invention] As explained above, in the present invention, the characters to be read and
A reference mark or character is displayed on the back side of a light-transmissive medium with marks written on both the front and back sides, and the slice value is determined based on the black peak value of the detected reference mark or character. Therefore, even if the light transmittance of the forms differs, the characters and marks written on the back side can be read accurately.

[Brief explanation of drawings]

Fig. 1 is a side view schematically showing an OCR used in an embodiment of the present invention, Fig. 2 is a plan view showing a form used in this embodiment, and Fig. 3 is a diagram showing the configuration of this embodiment. The block diagram shown in FIG. 4 is a circuit block diagram of the peak value detection section in FIG. 3. 1......Form 3...Light source 4...Reading head 5...・・・
・・・・・・Tip detection cell 6・・・・・・・・・・・・
・Form sending section 7...Photoelectric conversion section 8
......Peak value detection section 9...
......Binarization section 10...Format table 1
1...... Recognition section 12... System control section 13...
......First register 14.16...
Comparator 15... 2nd Register Representative Patent Attorney Sasa Suyama - Figure 1 Figure 2 Figure 3

Claims (2)

[Claims] (1) In a method of reading characters/marks recorded on both the front and back sides of paper or other medium having a certain degree of light transparency from one side at a time, a predetermined mark on the side opposite to the reading side of the medium is read. A reference mark or character is recorded at a position, and when reading, the reference mark or character is optically detected from the reading side, and the back side reading is performed based on the black peak value of the detected reference mark or character. 1. An optical character/mark reading method comprising determining a slice value for binarizing a read signal. (2) The reference mark or character is recorded with the same density as other characters/marks recorded on the same surface, and the slice value for binarizing the read signal is the black peak value of this reference mark. The optical character/marker according to claim 1 determined based on the standard