JPS6146875B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention scans characters with a photoelectric conversion unit, digitizes the output, compares it with a character pattern signal registered in advance, and uses the result to digitize the output. The present invention relates to a character reading device for reading the above characters.

2. Description of the Related Art In general, a character reading device is configured to scan a character using a photoelectric conversion unit, digitize the output, compare it with a pre-registered character pattern signal, and read the character when the two match. are doing.

Problems to be Solved by the Invention Incidentally, all conventionally used character reading devices scan characters, simply convert the result into binarization, and then compare it directly with a registered character pattern signal. Therefore, if the characters to be read are handwritten, the signal level of the character pattern depends on the pressure of the writer, and in the case of printed text, the signal level of the character pattern is determined by the old and new ribbon and ink, the shading, etc. Large variations occur, and characters often cannot be read accurately. In such cases, re-scanning is required each time, which poses a problem in that it takes a considerable amount of time to read.

The present invention eliminates the above-mentioned conventional drawbacks, and provides an excellent character reading device that does not require rescanning even if there is a relatively large variation in shading in the characters to be read, and therefore takes less time to read. The purpose is to provide the following.

Means for Solving the Problems In order to achieve the above object, the present invention converts an analog signal obtained by scanning characters to be read into a digital signal that can take three or more digital values depending on the respective levels. The digital signal in this memory is then binarized based on a predetermined reference digital value.
The binarized signal is compared with a pre-registered character pattern signal to determine the character to be read, and based on the binarized signal, the peripheral length bit of the character to be read is determined. Find the ratio between the total number and the total number of black bits, and if the ratio is not within a predetermined appropriate range, change the standard digital value for binarization so that it falls within the appropriate range, and then Regardless of the shade,
It is constructed so that the above-mentioned characters can always be accurately determined.

Therefore, according to the present invention, even if there is a relatively large variation in shading in the characters to be read due to the pen pressure of the person writing, the ribbon, old or new ink, shading, etc., the characters will not be stored in the memory. By changing the slice level of the digital value and obtaining a new binary signal, the characters can be read accurately using only electrical processing without rescanning, and the overall reading time can be shortened. have

Embodiment FIG. 1 is a schematic diagram of an embodiment of a character reading device of the present invention. In FIG. 1, 1 is a photoelectric conversion unit that scans the characters to be read and outputs an analog signal according to the shading of the character, and 2 is a plurality of predetermined standards for each of the analog signals obtained by the photoelectric conversion unit 1. an analog-to-digital converter that performs digital conversion based on the level to each digital value according to the level of the analog signal; 3 is a memory that temporarily stores the signal digitally converted by the analog-to-digital converter 2; 4 is a binarization unit that sequentially reads out the digital signals stored in the memory 3 and outputs a binary signal for so-called black-white determination, which is binarized based on a predetermined reference digital value; A character determination unit compares the binarized signal with a pre-registered character pattern signal and determines the character based on the match between the two; 6 is the peripheral length of the character to be read based on the output of the binarization unit 4; Total number of bits l and total number of black bits m
A peripheral length area calculation unit 7 that calculates the ratio l/m of the calculation unit 6 determines whether the ratio l/m calculated by the calculation unit 6 is within a predetermined appropriate range,
If it is not within the appropriate range, the binarization unit 4 and This is a final determination section that controls the determination section 5.

In the embodiment described above, when reading characters, first, one character or one line of characters is scanned by the photoelectric conversion section 1 as shown in FIGS. 2A and 2B. When a character is scanned, an analog signal is output at a low level for the character part and at a high level for the rest. The analog signal output from the photoelectric converter 1 is then input to an analog-to-digital converter 2, where it is converted into a digital signal with a digital value corresponding to the level of the analog signal. That is, in this embodiment, based on the three reference levels υ ₁ , υ ₂ , and υ ₃ , four digital values 00, 01, and
It is converted into 10 and 11 digital signals. Now, assuming that the analog signal obtained by the photoelectric conversion unit 1 is as shown in a of FIG. 3A and B, respectively, the 2-bit ( The signal is converted into a digital signal having four digital values, where b is the first bit and c is the second bit. This digital signal is temporarily stored in the memory 3 and then converted into a binarization unit 4.
The digital data is read out by the digital camera, compared with a predetermined reference digital value, and then binarized. That is, at this point, the digital signal represented by 2 bits is converted into a binary signal represented by 0 and 1 based on the reference digital value. Now, if the reference digital value predetermined by the binarization unit 4 is 10, the smaller digital values 01,
00 is converted to 0, and digital values larger than 0 are converted to 1, which are represented by b and c in FIG. 3A and B, respectively.

Each digital signal is converted into a binary signal represented by d in FIGS. 3A and 3B. The signal thus binarized is compared with a pre-registered character pattern signal by the character determination section 5, and the scanned character which is the original information of the binarized signal is is determined.

By the way, if the judgment result at this stage is the final judgment result, as shown in FIG. If the value is relatively small, there will be almost no 1 signal representing black in the binarized signal, and the character determining section 5 will not be able to accurately read the character. This also applies when the characters to be read are thicker or darker than the predetermined thickness or density. If the signal appears more than the predetermined value, the character determining section 5 will similarly be unable to read the character accurately.

Therefore, in the above embodiment, the binarized signal is further applied to the peripheral length area calculation unit 6, and the black signal 1 or the white signal at the outline position of the scanned character is determined from the binarized signal. The ratio l/m of the total number of peripheral length bits l, expressed as the total number of 0s, etc., and the total number of black bits, expressed as the total number of black signals, etc., is determined, l/m, and a signal corresponding to the ratio l/m is transmitted to the final determination section 7. ,
It is determined whether the ratio l/m is within a predetermined suitable range, and if it is not within the suitable range, the standard digital value is changed to change the standard digital value so that it is within the suitable range. control part 4 and again 2
I am trying to redo the value conversion and character judgment. Therefore, according to the above embodiment, even if the character to be read does not have a predetermined thickness or darkness, the character can always be read accurately.

This will be explained in more detail below.
Now, if the character scanned to be read is thinner or lighter than the predetermined thickness and density, the binary signal d as shown in Figure 3B is generated.
A signal of 1 representing black hardly appears in the image, and the ratio l/m of the total number of peripheral length bits l to the total number of black bits m becomes smaller than a predetermined appropriate range. Therefore,
In this case, the final determination unit 7 controls the binarization unit 4 to lower the reference level value of the binarization unit 4 from 10 to 01, and performs the binarization and character determination again. If this is done, an appropriate amount of 1 signals representing black will appear in the binarized signal, as shown by e in FIG. This is within a predetermined appropriate range, and the character determination section 5 can accurately determine the character.

If the character scanned to be read is thicker or darker than the predetermined thickness or darkness, more 1 signals representing black will appear in the binary signal than the appropriate amount. When the ratio l/m of the total number of peripheral length bits l to the total number m of black bits becomes larger than a predetermined appropriate range, the final determination section 7
The binarization unit 4 is controlled to increase the reference level value of the binarization unit 4 from 10 to 11. Therefore, in this case as well, an appropriate amount of a signal representing black will appear in the binarized signal again, and the character determination section 5 will accurately determine the character.

In the above embodiment, the analog signal obtained by the photoelectric conversion unit 1 is divided into 3 of υ ₁ , υ ₂ , and _υ
Based on the two standard levels, there are four different
The analog-to-digital converter 2 that converts into a 2-bit digital signal represented by three digital values (00, 01, 10, 11) is, for example, a known parallel comparison type.
This can be easily realized using an AD converter. Further, the binarization unit 4 that converts the digital signal obtained by the analog-to-digital conversion unit 2 into a binary signal represented by 0 and 1 based on a predetermined reference digital value is a known one, for example. This can be easily realized using a digital comparator.

Effects of the Invention As is clear from the above embodiments, the present invention converts the analog signal obtained by the photoelectric conversion unit into a digital signal that can take three or more digital values according to the respective levels, and stores the converted signal in a temporary memory. The digital signal stored in this memory is binarized based on a predetermined reference digital signal, and the binarized signal is compared with a preregistered character pattern signal to determine the character to be read. Also, the ratio of the total number of peripheral length bits and the total number of black bits of the character to be read is determined based on the binarized signal, and if this ratio is not within a predetermined appropriate range, it is adjusted to within the appropriate range. like 2
It is configured to automatically change the reference digital value when converting into a value, and it can vary relatively large shades and thicknesses depending on the pen pressure of the person writing on the characters to be read, the old and new ribbon, ink, etc., and the density. Even if there is a variation in the value, the above characters can be read accurately by changing the slice level of the digital value stored in the memory and obtaining a new binary signal without rescanning and only by electrical processing. It is possible,
This has the effect of shortening the reading time as a whole.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an embodiment of the character reading device of the present invention, FIG. 2 is a diagram for explaining character scanning in a photoelectric conversion section constituting the embodiment, and FIG.
The figure is an operation explanatory diagram for explaining the operation of the same embodiment. 1... Photoelectric conversion section, 2... Analog-digital conversion section, 3... Memory, 4... Binarization section, 5...
Character determination unit, 6... Perimeter length area calculation unit, 7... Final determination unit.

Claims (1)

[Claims] 1. A photoelectric conversion section that scans the characters to be read and outputs analog signals according to the shading of the characters, and converts the analog signals obtained by this conversion section based on a plurality of predetermined reference levels, respectively. 3 different depending on the level of the analog signal above
an analog-to-digital converter that converts the digital signal into a digital signal that can take on more than one digital value, a memory that temporarily stores the digital signal converted by the converter, and a memory that reads the digital signal stored in the memory. 2. Binarize the digital signal based on a predetermined reference digital value and output a binary signal for black-white determination.
a digitization section; a character determination section that compares the output of the binarization section with pre-registered character pattern signals and determines the character to be read; a peripheral length area calculation unit that calculates the ratio between the total number of peripheral length bits and the total number of black bits;
When the ratio obtained by this calculation section is not within a predetermined appropriate range, the binarization section
A character reading device comprising a final determination section that controls the binarization section so that the ratio of the reference digital value for digitization falls within the appropriate range.