JPH0217585A - Optical character reader - Google Patents

Abstract

PURPOSE:To obtain only recognition results of high reliability by calculating the angle of inclination in accordance with the vertical length of continuous black picture elements and omitting the recognition processing in the case of this angle of inclination larger than a preliminarily determined angle. CONSTITUTION:A character string height detecting circuit 41 obtains the number of continuous black picture elements of the signal sent from a visual field position detecting circuit 9. An inclination calculating circuit 42 calculates the angle of inclination of a scanner 1 to a form 3. A discriminating circuit 43 discriminates whether this angle of inclination is smaller than the preliminarily determined allowable angle of inclination or not, and a recognition processing stop signal is sent to a control circuit 16 when the former is larger than the latter, but a recognition processing start signal is sent to the control circuit 16 when the former is equal to or smaller than the latter.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is capable of scanning characters, symbols, etc. (hereinafter, only characters will be described as a representative, but the same applies to symbols as well) by scanning a document with a hand-held scanner. The present invention relates to an optical character reading device that reads (a).

[Conventional technology]

At supermarkets, department stores, etc., POS (Point
at 5ales) system is widespread. This p.

Hand-held optical character readers are often used in S systems.

The present applicant has filed a patent application for such a device as shown in FIG. 2 in Japanese Patent Application No. 41474/1983.

In FIG. 2, reference numeral 1 is a scanner, and with hand 2, paper 3 is
It reads the characters stored on the paper 3 just by placing it on the paper. The paper 3 is, for example, a price tag on which information for a POS system is stored. 4 is a light source, 5 is a lens system, and 6 is an image sensor, which requires a field of view of at least one line of characters written on paper 3, and in the illustrated example, the field of view is one line horizontally and one vertically. The field of view is about three times that of text. Reference numeral 7 denotes a control/binarization circuit that converts the analog signal that is the output signal of the image sensor 6 into binary signals corresponding to the character area and the background area, respectively, and sends the signals to the memory 8. The memory 8 stores the binarized signal of the entire field of view of the image sensor 6.

Recognition processing is performed from the binarized signals stored in the memory 8, but in the example shown, only the binarized signals in which characters are correctly within the visual field are subjected to the recognition processing. That is, the third
The figure shows an example of scanning with the image sensor 6 and converting it into binarization, and this figure shows a case where characters are correctly included in the field of view 17. FIG. 4 shows a case where scanning is performed with characters protruding from the visual field 17. In this case, the recognition process described in detail later is not performed, and as the scanner 1 moves, the image sensor 6 scans again, binarizes it, and stores the binarized signal in the memory 8 to improve the reading speed. ing. Note that in FIGS. 3 and 4, some vertical lines indicating pixel divisions are omitted.

The visual field position detection circuit 9 determines whether or not to perform recognition processing. That is, the visual field position detection circuit 9 operates in parallel with storing the binarized signal into the memory 8, and determines whether or not to perform recognition processing almost at the same time as the memory 8 finishes storing the binarized signal. Deciding. Furthermore, when performing recognition processing, the visual field position detection circuit 9 does not process the entire visual field;
The recognition area is determined so that only the area where characters exist is recognized.

An example of a specific configuration of the visual field position detection circuit 9 is shown in FIG. As shown in the figure, the visual field position detection circuit 9 includes each row OR circuit 21 consisting of an OR gate 23 and a register 24;
The determination circuit 22 includes a ROM 25 and a register 26.

Each row OR circuit 21 performs an OR operation for each row between first-order pixels (19 in FIG. 3, from the Bt column to the Bu column) approximately in the horizontal center of the field of view of the image sensor 6. That is, when the control/binarization circuit 7 sends a binary signal as shown in FIG. At the same time, the logical sum of the binarized signals from the B(column to the Bu column) in each row is determined by the respective row logical sum circuit 21.

To further comment, the register 24 is first cleared, and when the signal in the Bt column of the L1 row is input to the OR gate 23, it is ORed with the output signal of the register 24, and the result is stored in the register 24. , Bu column, the result of the logical sum operation in the L1 row is stored in the register 24. When the logical sum up to the Bu column is determined, the contents of the register 24 are sent to the determination circuit 22, and at the same time, the register 24 is cleared. As a result, the result of the logical sum from the L1 row to the LP row is sent to the determination circuit 22. Based on the result of the logical sum for each row, it can be determined whether or not there is a binarized "black" in each row.

The configuration and operation of the determination circuit 22 to which a signal representing the result of the logical sum is supplied are as follows.

That is, the signal representing the result of the logical sum of each row in the determination circuit 22 is input to the ROM 25, and the contents read from the ROM 25 are stored in the register 26. Since the state transition indicating a change in the black and white state is coded and written in the ROM 25, the register 26 stores the black and white state up to that row, which is the result of the logical sum of the 0th row. The signals from the register 24 indicating the current state and the register 26 indicating the previous state are input to the ROM 25, and the signal of the new state is stored in the register 26. SET, EN in ROM25
D. A code corresponding to the CLEAR signal is written. When the signal SET changes from white to black, EN
D is output when black continues for a certain number of times (corresponding to the height of the character) and changes to white, and the character position is from the SET line to the END line. On the other hand, when the signal SET and signal END are not output up to the bottom rows t and p,
A CLEAR signal is output to the control circuit 16, which clears the memory 8. In this way, subsequent recognition processing is not performed, and a new binarized signal is acquired by scanning again.

In the above example, when calculating the logical sum for each row,
The reason why only the center part is used instead of the symbol for the entire horizontal row of the field of view is to avoid the influence of noise, such as when the paper 3 is smaller than the field of view or when black marks are printed on the paper 3 outside the characters to be read. This is to minimize it as much as possible. - As an example, the area 19 in FIG. 3 is a portion for calculating a logical sum.

The new line detection circuit 10 determines the character position from the signals SET and END sent from the visual field position detection circuit S, and compares it with the character position determined by the SET and END signals sent in the next scan to determine if the character position has changed! ! ! (number of pixels) or signal CL
Judgment is made based on whether the character string has protruded once from the field of view 17 by EAR, and if it is determined that a new character string exists, a signal NEW is sent to the recognition processing circuit 15.

After the signal NEW is sent, the next recognition process is performed.

With this new line detection circuit 10, when reading a character string with more lines than the field of view, it is only necessary to move the scanner 1 from top to bottom or from bottom to top.

That is, since the scanner 1 is placed on the paper 3 and the characters are read,
If left for a long time, the same part will be scanned and read over and over again, but the new line detection circuit 10 prevents this.

Next, cutting out one character will be explained.

Since the binarized signal stored in the memory 8 is the entire field of view of the image sensor 6, the amount of data is larger in number of pixels both horizontally and vertically than the number of pixels that can be processed by the recognition processing circuit 15 that recognizes and processes one character. In other words, it is necessary to convert each character into a binary signal.

The number of pixels that can be processed by the recognition processing circuit 15 will be explained assuming that the number of pixels that can be processed by the recognition processing circuit 15 is n horizontally and m vertically (column direction) in FIG.

First, a portion of the binarized signal having the number of pixels P of the entire field of view 17 by n horizontally and vertically is transferred to the buffer 11 . In other words, some of the binarized signals from columns B1 to Bn from rows L1 to L are buffered in buffer 1.
It is stored in 1.

The vertical position detection circuit 12 detects the vertical position of one character in the binary signal of the partial buffer 11, and reduces the binary signal to m pixels in the vertical direction that can be processed by the recognition processing circuit 15. . The vertical position detection circuit 12 determines the vertical position of the character, and the recognition processing circuit 15 determines the number m of vertical pixels (determined so that the character position is located approximately at the center). As a result, the vertical direction m is determined from the binary signal stored in the minus digit buffer 11 and transferred to the single character buffer 14 as one character data mXn. In the example shown in FIG. 3, the binary signal contained in the area from rows Ll to Lm and columns B1 to Bn is transferred to the single character buffer 14 as one character data.

The lateral position detection circuit 13 determines the horizontal position of the binarized signal to be stored when the next binarized signal is stored in the negative digit buffer 11. At this time, one pixel at a time may be moved in the horizontal direction and stored in the negative digit buffer 11, but the same character may be stored many times, which takes a long processing time. 13 detects the number of pixels up to the next character, shifts it horizontally by this number of pixels, and
, a part of the binarized signals of the vertical p pixels is stored in the buffer 11.

The contents of the partial buffer 11 are, for example, as shown in FIG.
It changes as shown in (b) and (C).

The recognition processing circuit 15 recognizes one character from the binary data stored in the one-character buffer 14, and may be of a known type, such as that described in Japanese Patent Publication No. 59-6418. That is, the recognition processing circuit 15 extracts feature data of character constituent parts for each row or column in the vertical and horizontal character areas, and outputs character recognition results corresponding to the type and appearance order of this feature data.

[Problem to be solved by the invention]

In conventional optical character reading elements, the part for calculating the logical sum in the visual field position detection circuit 9 is set to be smaller than the visual field, so when reading a character string larger than the number of pixels for calculating the logical sum, the following The following problems arise. As shown in FIG.
An inclination occurs between the paper 3 and the paper 3, as shown in FIG.
If a part of the character protrudes from the visual field 17, the visual field position detection circuit 9 makes a logical sum of 30, determines that the character string is correctly within the visual field 17, and performs recognition processing. If this happens, some characters may be skipped, resulting in incorrect recognition results. In the example in Figure 7, the numbers ``7'' and ``8'' in 31.32 are partially outside the field of view 17 and cannot be read. The result is the number 33 “9
” protrudes from the field of view 17 and there are no characters,
Is the recognition result rE123456? ? J or 31.
In some cases, the numbers ``7'' and ``8'' in 32 are considered noise, and in that case, it becomes ``rE123456.''
There is a problem with data errors.

The present invention aims to solve this problem and prevent errors caused by tilting between the scanner and the paper.

[Means to solve the problem]

In the present invention, the visual field position detection circuit 9 calculates the inclination angle from the continuous vertical length of "1 black" or "l" from the result of calculating the logical sum, and if the angle is greater than a predetermined angle, recognition processing is performed. Errors can be eliminated by re-scanning without performing this process.

To explain using FIG. 8, the length of the area for which the logical sum is calculated by the visual field position detection circuit 9 is a, and the result of calculating the logical sum is "
Since the height of the continuous length C11 character that becomes black "1" is determined in advance, if this is b, (the height θ can be calculated as follows.The value of θ for recognition processing is determined in advance. , when θ is larger than this, F&I processing is not performed to prevent errors.

Also, the character position is when the logical sum "black" or "1" part is not at the edge of the visual field, but when there is always a "white" part like d in Part 8, so d Alternatively, θ may be determined from the position of .

The same is true when it is located below the visual field.

〔Example〕

FIG. 1 shows an example of the configuration of the present invention. 1 to 16 are the same as those of the conventional device shown in FIG. 2, so their explanation will be omitted. Reference numeral 41 denotes a character string height detection circuit, which includes a counter that adds up signals from SET to END sent from the visual field position detection circuit 9. The zero-order slope calculating circuit 42, which calculates the number of consecutive pixels of the logical sum "black", calculates the slope θ of the scanner 1 and the sheet 3 stop described above using equation (1). Here, a and c are predetermined. It is determined whether θ calculated by the first calculation circuit 42 is smaller than a predetermined allowable tilt angle α.

If θ is larger than α, a recognition processing stop signal is sent to the control circuit 16. If θ is smaller than or equal to α, a recognition processing start signal is sent to the control circuit 16.

C. Effects of the Invention] According to the present invention, even if the scanner reads at an angle, there will be no erroneous recognition processing, and only highly reliable recognition results will be output. Furthermore, since the operator can read without worrying about the tilt of the scanner, the operational burden can be significantly reduced.

[Brief explanation of the drawing]

FIG. 1 shows a configuration example of an optical character reading device according to the present invention, FIG. 2 shows a configuration example of an optical character reading device according to the prior art, and FIG.
4 and 4 are explanatory diagrams conceptually showing the field of view of the image sensor, FIG. 5 is a bracket diagram showing the specific configuration of the field of view position detection circuit, and FIGS. 6 (a) to (C) are diagrams. FIG. 7 is an explanatory diagram conceptually showing the contents of the one-character memory, FIG. 7 is an explanatory diagram of the case where an error occurs due to the inclination, and FIG. 8 is an explanatory diagram of the calculation of the inclination angle. 1...Scanner, 2...Hand,
3...Paper, 4...Light source,
5... Lens system, 6... Image sensor, 7... Control/binarization circuit, 8... Memory, 9... Visual field position detection circuit, 10...New line detection circuit, 11...-digit buffer, 12...Vertical position detection circuit, 13...Horizontal position detection Circuit, 14...Character buffer, 15...Recognition processing circuit, 16...Control circuit, 17...Field of view, 18... -Number of horizontal pixels in character recognition processing, 19
・・・・・・Pixel that takes the logical sum in the visual field position detection circuit, 2
1... Each row OR circuit, 22... Judgment circuit, 23... OR gate, 24... Register, 25...
...ROM. 26...Register, 30...Result of OR, 31.32.33...Character, 41...Character string height detection circuit, 42.・・・・・・
- Slope calculation circuit, 43...determination circuit. Patent applicant: Sumitomo Electric Industries, Ltd.

Claims (1)

[Claims] (1) In a hand-held optical reader that optically reads characters, symbols, etc., photoelectric conversion elements are arranged in a planar manner,
an image sensor that fits at least one line of characters, symbols, etc. within its field of view; a binarization circuit that converts analog symbols output from the image sensor into binary signals corresponding to a character area and a background area; A means for storing the signal from the binarization circuit, a means for detecting a character area from the logical sum of black in an area smaller than the field of view, a means for detecting the character area from the logical sum of black, and a means for detecting the character area from the logical sum of black in an area smaller than the field of view. An optical character reading device comprising means for calculating a relative angle between characters and a means for recognizing characters, and performing recognition processing only when the relative angle between the character string and the field of view is within a permissible range. .