JPS60246489A - Optical character reading method - Google Patents

Abstract

PURPOSE:To generate no read error even if a business form expands and contracts by a variation of temperature and humidity, by providing a detecting means of a position of the business form. CONSTITUTION:When running of a business form 1 is started, a scanning line 7 is projected onto a semiconductor CCD sensor 19. A binary-coding circuit 20 converts an analog data obtained by the CCD sensor 19 to a digital data and stores it in a memory 21. Also, a length of the business form 1 is forecast and programmed in advance, but its actual length is varied in accordance with a variation of temperature and humidity. Therefore, a business form detector 30 is provided, an actual length of the business form 1 is measured based on the time when the business form 1 passes through the business form detector 30, and the length programmedin advance is corrected.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an optical character reading method, and more particularly to an optical character reading method that performs scanning using a -dimensional semiconductor sensor and paper feed to correctly read a form without line marks. It is.

[Background of the invention]

In an optical character reader using a semiconductor CCD sensor, the first
As shown in the figure, the paper feed mechanism (
(not shown) to run at a constant speed in the direction of arrow 6,
Irradiate the top of form 1 with lamp 18.

An image of a line 7 perpendicular to the arrow 6 on the form l is projected onto the semiconductor CCD sensor 19 by the lens 14.

The semiconductor CCD sensor 19 is, for example, a 2048-bit sensor.

By inputting a clock, each photosensing cell sequentially outputs an electric signal corresponding to the input light to the binarization circuit 20. 2 in the binarization circuit 20
The digitized signal is stored in the memory 21, then read out and input to the recognition circuit 22, where the recognized result is sent to the control unit IO.

The memory 21 shown in FIG. 1 generally has a capacity sufficient to store one line's worth of signals, and stops the paper feeding mechanism after one line's worth of signals is input. For this purpose, a line mark 8 is printed on the form 1, and when the line mark 8 is detected by a line mark detector (not shown), a detection signal is sent to the paper feed mechanism. Form 1 is sent to paper feed 1 mechanism and stopped after traveling one line.

In this way, in FIG. 1, since the line position can be detected by the line mark 8, there is an advantage that even if the form l expands or contracts due to changes in temperature and humidity, the effect on reading is small.

However, since it is necessary to print the line marks 8 on the form 1, the cost of printing the form increases and there are significant constraints on the form design.

On the other hand, the distance from the leading edge of the form 1 is programmed in the control unit 10, and by utilizing the fact that the running speed of the form 1 is constant, the time after the leading edge of the form 1 passes the scanning line 7 is determined. It is also possible to detect rows. According to this method, the line mark 8 is not required, but since the running speed must be kept constant with high precision, the paper feeding mechanism becomes expensive, and expansion and contraction of the paper due to temperature and humidity cannot be corrected. Since the rollers in the paper feeding mechanism are usually made of rubber or the like, the roller diameter changes depending on temperature and humidity, and the roller surface wears out due to long-term use, causing the roller diameter to change.

The expansion and contraction of paper due to temperature and humidity is a maximum of ±2%, that is, the length of 3
For form 1 of 00■, it is expanded or contracted by ±6III11. Therefore, in the worst case, the characters written at the rear end of the form 1 of 3001II11 will be shifted upward or downward by 61m11, and this value will be affected by small characters, such as printed letters (about 2 cm in height).
．． 5/lI1m) is printed on form l, it becomes a fatal value and accurate reading becomes impossible.

[Object of the Invention] The object of the present invention is to solve such problems when reading data on a form that does not have line marks by scanning with a one-dimensional semiconductor sensor and paper feed.

To provide an optical character reading method capable of accurately reading a field without being affected by expansion and contraction of paper due to changes in temperature and humidity.

[Summary of the invention]

The optical character reading method of the present invention stores the binarized signal of the entire document in a memory, and compares the length of the document measured by a document detector that detects the document on a scanning line with the length of the document programmed in advance. The feature is that the reading position on the form is corrected based on the comparison.

[Embodiments of the invention]

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

FIG. 2 is a schematic diagram of an optical character reader showing an embodiment of the present invention.

The form I to be read is moved at a constant speed in the direction of arrow 6 by a paper feed mechanism (not shown). The running of the form 1 is started in response to a start signal from the control unit 1O. When the scanning line 7 is irradiated by the lamp 1, the scanning line 7 is projected onto the semiconductor CCD sensor 19 by the lens 14. The semiconductor CCD sensor 19 is composed of, for example, a 2048-bit photodetection cell, and clock oscillation! I (not shown)
Analog electrical signals corresponding to the irradiation light of each photodetection cell are sequentially outputted to the binarization circuit 20 using a clock from . For example, set the magnification of the lens 14 to 8 lines/1II11 on the paper surface 1.
If the resolution is set to be , the scanning line 7 with a width of 256 ma+ in the 2048-bit semiconductor CCD sensor 19
is projected. Further, the semiconductor CCD sensor 19 can be replaced with a one-dimensionally arranged photo-play.

The binarization circuit 20 performs shading correction on the input analog electric signal, binarizes the black signal into rL I Hg and the white signal into 0'' using a slice circuit, and stores the signal in the memory 2.
1 and store it. The memory 21 can write one byte of binary signals, for example, eight signals. The state of the memory 21 is a 2048-bit semiconductor C.
Using the CD sensor 19, the resolution is 8 lines/llll11, and the size of the form l to be read is, for example, A4 size (
210+1mX 297m+s), approximately 600
I have a part-time job.

Further, the memory 21 can be read out from the recognition circuit 122 at any address, and for this purpose the recognition circuit 22 reads the memory 2 of the field on the form 1 to be read from the control unit 10.
1 is input, a binary character pattern to be read is read from the memory 21, this is recognized, and the result is output to the control section 10.

The control unit 1O has a function of controlling the reading method of the form 1 programmed in advance by the user, controlling the paper feeding mechanism, outputting the programmed information field by field to the recognition circuit 22, and inputting recognition results from the recognition circuit 22. It has functions such as output editing, but these functions can be easily realized by using a microcomputer.

FIG. 3 is an explanatory diagram of the reading position correction method on the form in FIG. 2.

Now, if you scan with the original 8 lines/1111 pitch,
Assuming that the length of the form 1 is 3001 mm, the total number of scanning lines is 2400 (nominal).However, as a result of measuring the passing time of the form with the form detector 30, 2
When 640 scanning lines were counted, a 10% elongation was detected, so when reading the first field 2, the 80th line was corrected from the 88th line, and when reading the second field 5, the 2320th line was corrected. 2
Correct it to S52nd or 6th. This correction can be easily executed by the program of the control unit 10.

FIG. 4 is a flowchart of a reading operation showing an embodiment of the present invention.

The contents programmed in advance by the user into the control unit 10 include the coordinates of fields to be read on the form, character types, and the reading order of the fields.

First, in step 31, the control unit 10 sends a start signal to the paper feed mechanism, and the form 1 to be read is moved at a constant speed by the arrow 6.
drive in the direction of. Next, in step 32, when the form 1 is run on the scanning line 7 by the paper feed mechanism, the form detector 30 detects this and notifies the control unit 10, so that the binarization circuit 20 The binary signal of is stored in the memory 21.
is stored in The form detector 30 can be easily detected by placing a photodetector such as a solar cell below the scanning line 7 and determining whether the amount of light from the lamp 18 is blocked by the form 1 or not.

At this time, in step 33, the control unit 10 clears and sets the measurement timer, and simultaneously starts writing to the memory 21. In step 34, it is determined whether the form detector 30 is turned off.

The control unit 10 determines that the form 1 has passed through the scanning line 7 when the light from the lamp 18 enters the form detector 30 again.

At this time, in step 35, the control unit 10 reads the timer value and at the same time stops writing to the memory 21. Further, in step 39, the running of the form 1 is also stopped. The memory 21 is as described above.

It has a sufficiently large capacity and can binarize and store all the image data on the input form l at the specified resolution.

In step 36, the control unit 10 calculates a correction value using the programmed length of the form 1 and the timer value. That is, the passing time of the form 1 is measured by the form detector 30 using a timer, and from this time, the actual length of the form 1 is calculated using the fact that the traveling speed of the form l is constant. The length of form l is corrected.

At step 40, the control unit 10 starts reading from the memory 21. The control unit 10 recognizes the characters of the fields to be read according to a preprogrammed order. For example, if field 2 is programmed as the first field to be read first, then The location of is converted into an address on the memory 21.

That is, in step 37, the coordinates of the first field are corrected and the address is converted. Address conversion is performed sequentially from the top of form 1 at a specified resolution (for example, 8 lines/w).
In) is stored in the memory 21, so it can be easily calculated by correcting the previously programmed length of the form 1 and the measured length.

Next, in step 38, the character pattern in the memory 21 is read out and input to the recognition circuit 22. That is, the recognition circuit 22 reads the binary signal of the address input from the control unit 10 from the memory 21.

After recognition, the result is output to the control unit 10.

Returning now to step 37, the second field programmed to be read next (e.g. field 5
) Proceed to coordinate correction.

By repeating these operations, any field can be read without being affected by the expansion and contraction of a sheet of paper.

In the embodiment, the output of the binarization circuit 20 was explained as a black signal II I IT and a white signal 1104', but a multi-level digitized signal is sent to the memory 2 according to the shade.
You can also store it in 1. In this case, the memory 21
It is necessary to increase the capacity of

Further, in the embodiment, eight binarized signals are configured as one byte and inputted to the memory 21, but an encoding circuit is provided between the binarization circuit 20 and the memory 21, and an encoding circuit is provided between the memory 21 and the recognition circuit 22. The capacity of the memory 21 can be compressed by inserting a decoding circuit into each of them and performing run-length encoding, for example, by an encoding circuit.

In addition, although the form detector 30 is provided in the embodiment, the form 1 can also be detected by monitoring the level of the analog electrical signal of the semiconductor CCD sensor 19 without providing this.
It is possible to detect This takes advantage of the fact that there is a difference in level between when the form I is on the scanning line 7 and when it is not.

In addition, in the embodiment, after all the binarized signals of the form 1 are stored in the memory 21, character recognition processing is performed while correcting the length of the form 1. However, the throughput of reading the form 1 is To improve this, by adding logic to detect the storage status in the memory 21, characters are recognized immediately after the field to be read is stored in the memory 21 without performing length correction, and finally, Measure the length of form 1, compare it with the length of form 1 programmed in advance, and if there is no expansion or contraction, do not perform expansion or contraction correction.
If expansion/contraction is measured, character recognition may be performed while correcting expansion/contraction again. This results in
The throughput can be improved when reading the form 1 which has a small degree of expansion and contraction.

〔Effect of the invention〕

As explained above, according to the present invention, a memory having a capacity that can store the binarized signal of the entire document is provided, and the expansion/contraction correction of the #A slip is performed after the binarized signal is stored. Any field can be read accurately without being affected by the expansion and contraction of the paper.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an optical character reader using a conventional semiconductor CCD sensor, Fig. 2 is a block diagram of an optical character reader showing an embodiment of the present invention, and Fig. 3 is a block diagram of an optical character reader using a conventional semiconductor CCD sensor. FIG. 4, which is an explanatory diagram of the reading position correction method, is a flowchart of the reading operation showing an embodiment of the present invention. 1: Form, 2, 3, 4, 5: Field to be read,
6: Form running direction, 7: Scanning line, 8: Line mark, lO
: Control unit, 14: Lens, 18: Lamp, 19: Semiconductor CCD sensor, 2o: Binarization circuit, 21: Memory, 22
: recognition circuit, 3o: form detector. Figure 1 Figure 2 Figure 3 Figure 1

Claims (1)

[Claims] In an optical character reading method that scans using a one-dimensional semiconductor sensor and a paper feed mechanism, all fields on the form to be read are continuously digitized and stored in memory, and the form is measured by a form detector that detects the form on a scanning line. An optical character reading method characterized in that the length of the written form is compared with the length of the form programmed in advance, the coordinates on the form are corrected, and the read address of the memory is converted.