JP2576370B2 - ID mark reading device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ID mark reading device for reading an ID mark (identification mark) attached to an object, and more particularly to a serial printer having a function of reading and writing ID marks. , An ID mark reading device.

[0002]

2. Description of the Related Art FIG. 9 is a plan view showing the shape of an ID mark. This is used for a serial printer having an ID mark read / write function, where (A) is a low density mode and (B) is a high density mode. ID mark is composed of a bit marks M and spaces S Rutoto
Moni, start mark 1, stop mark 2 and data
Division 3 The data section 3 has a variable length and stores 1 to 5 bytes of information in the low-density mode and 1
Up to 15 bytes of information can be provided. A parity 4 of 1 byte length is always added at the end of the data section 3,
Used for checking the data section 3. Data part 3
Is shown as bit mark 5 in FIG.
When one byte of data unit 3, eight bi arranged at regular intervals
It is composed of Tsu door mark 5. Bit mark 5 is an example
For example, if it is printed in black, the bit is “1”,
If it is blank, it is "0".

A conventional ID mark reader of this type has a conversion circuit for binarizing the output of the light receiving sensor into 1 or 0, and can also convert the result of the binarization performed by hardware. And decoding was done. Known materials include JP-A-60-100272.

[0004]

SUMMARY OF THE INVENTION Such a conventional ID
In the mark reading device, the result of scanning the ID mark by the light receiving sensor is stored as binary data performed by hardware . Therefore, when the binarization process did not go well, the only way to reread was to do so.

[0005] Further, the sensitivity of the light receiving sensor is degraded.
ID on paper that is dirty or dark paper other than black
When the mark is printed, the dynamic range of the output of the light receiving sensor when the ID mark is read becomes small. However, even in such a case, since the binarization is performed by hardware , there is a problem that the determination threshold value of 1 or 0 cannot be changed and reading cannot be performed.

Also, since the start mark of the ID mark is printed on the upper left of the sheet, the focus of the light receiving sensor tends to be out of focus due to the floating of the sheet. In such a case, the output of the light receiving sensor with respect to the start mark does not change.
There is a problem that reading cannot be performed even if all other data is normal.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ID data reading apparatus capable of obtaining an accurate decoding result even when the output voltage of the light receiving sensor shifts up and down as a whole. Another object of the present invention is to enable re-execution of only software processing when a decoding result is abnormal.

[0008]

To achieve the above object, according to the Invention The, ID mark reading apparatus according to the present invention. Argument
A bit mark meaning a logical 0 or 1 and this bit
The position between the mark and the space
A light-receiving sensor that detects reflected light from the ID mark obtained from the position of the top mark and converts the reflected light into an electric signal for each fine width ; An A / D converter for converting the electric signal into a digital value of 2 bits or more ; Storage means for storing the digital value ; The digital value stored in the storage means averages for each of the bits Ma <br/> over click and the space, the digital value and the space adjacent to the bit mark of the bit marks are those averaging Decoding means for obtaining a difference from the digital value, comparing the difference with a threshold value, and outputting a binarized decoding result of the bit mark ; Determining means for determining whether the decoding result is normal ;
And retry means for changing the threshold value when the decoding result is abnormal and outputting the decoding result from the decoding means again.

Further, the storage means and the retry means are omitted, and the digital value is averaged for each of the bit mark and the space instead of the decoding means, and the averaged digital value of the bit mark is obtained. And a digital value of the space adjacent to the bit mark may be obtained, and the difference may be compared with a threshold value to output a decoding result obtained by binarizing the bit mark. .

[0010]

The light reflected from the ID mark is converted into an electric signal for each fine width by the light receiving sensor. These electric signals are converted into digital values of 2 bits or more by an A / D converter. In the decoding means, the digital value is averaged for each bit mark and space of the ID mark,
These differences are compared with a threshold value. Since the digital value is a value of 2 bits or more, the difference has various values. Then, a decoding result is output based on the comparison result. Since it is not a comparison between the absolute value of the digital value and the threshold value, a decoding result can be obtained if the difference is equal to or more than a certain value even if all the digital values rise or fall.

[0011] Further, in the case where storage means, determination means, retry means and the like are added, when the determination means determines that the decoding result is abnormal, the retry means changes the threshold value and the decoding means again. The difference is compared with a new threshold, and a new decoding result is output.

[0012]

FIG. 1 is a block diagram showing the principle of an ID mark reading apparatus according to the present invention. The ID mark reading device 50 according to the present invention detects the reflected light 54 from the ID mark 52 and converts it into an electric signal for each fine width.
An A / D converter 17 for converting the electric signal into a digital value of 2 bits or more, a storage means 56 for storing the digital value, and a bit mark of the ID mark 52 for storing the digital value stored in the storage means 56 M and space S
A decoding means 58 for averaging each time and comparing the mutual difference with a threshold value and outputting a decoding result; a judging means 60 for judging whether or not the decoding result is normal; and a case where the decoding result is abnormal. And a retry means 62 for changing the threshold value and outputting the decoding result from the decoding means 58 again.

FIG. 2 is a block diagram showing an embodiment of the present invention. In this figure, the storage means 56 in FIG. 1 is realized by the print buffer 18, and the decoding means 58, the judgment means 60 and the retry means 62 in FIG. 1 are realized by the host CPU 6, the printer CPU 9, and the like.

When an ID mark read command is sent from the host CPU 6, the print controller 7 urges the mechanism controller 8 to execute reading of an ID mark. Mechanism control unit 8 receives this, ON the light receiving sensor 16 moves the scan pacing motor 14 via a spacing motor <br/> motor driver 11, scans the ID mark. The output of the light receiving sensor 16 is sampled at a constant cycle. The sampled output signal of the light receiving sensor 16 is output to the A / D converter 1
7 and converted into 8-bit data. This 8
The bit data is stored in a print buffer 18 that stores print image data.

FIGS. 3 to 5 show an example of analyzing data recorded on an ID mark. The whole process is roughly divided as shown in FIG. 3, a digitizing process (step 101) for converting the output of the light receiving sensor 16 into 8-bit data and storing it in the print buffer 18, and analyzing the information of the ID mark to obtain a code. Decoding process (step 102),
It is determined whether the decoding result is normal (step 10).
3), the process ends if normal, abnormal if the decoding process (for re-executing the step 102), the retry process of changing the conditions such as bit <br/> mark black / Blank threshold (Step 104). The details of each process are described below.

FIG. 4 shows a process until the output of the light receiving sensor 16 is decoded (one byte of data). One byte of the data portion of the ID mark is “D2
h ", the ID mark looks like 21.
The white squares in the figure do not actually print anything. The change in the output voltage (analog waveform) when the light receiving sensor 16 scans over this is 22. The interval between the graduations provided below this waveform is the data sampling period.
(N) is a sampled voltage value. This voltage is supplied to the 8-bit data D through the A / D converter 17.
(N) and stored in the print buffer 18. Similarly, at the next sampling, the voltage A (n + 1) is converted by the A / D converter 17 to become D (n + 1) and stored in the area next to D (n) in the print buffer 18.

In this manner, all the ID marks are scanned,
When the output is stored in the print buffer 18 as 8-bit data, a decoding process 19 (step 10) is performed.
3. Details will be described later) to obtain the result "D2h".

After decoding is completed for all ID marks, a data check is performed.
If the data check is abnormal, a retry process (step 104, details of which will be described later) for changing a condition suitable for the error situation is executed, and the decoding processing unit 19 (step 10).
Perform 2) again.

FIG. 5 is a flowchart of the decoding process, and FIGS. 6 to 8 show data processing in the decoding process.

In this processing, first, a start mark is detected (step 29). Here, the predetermined start mark / stop mark detection threshold value 36 is compared with the 8-bit data stored in the print buffer.
The arrangement of the first 8-bit data larger than the threshold value is used as a start mark, and it is determined whether the mode is the low-density mode or the high-density mode based on the shape. In addition, a start mark position 37 (address of the print buffer 18) is stored as a base point for decoding. At this time, if the start mark 1 cannot be detected or does not match any of the high-density mode / low-density mode shapes, a start mark error is generated (step 33), and the process branches to retry processing (step 104).

When the start mark 1 is found, a stop mark detection process is performed next (step 30). Here, the position of the stop mark is obtained by calculation based on the start mark position 37, and the 8-bit data of the print buffer 18 in the search range 38 in the vicinity thereof is compared with the threshold 36 to detect the stop mark 2. When the stop mark is detected, the position on the print buffer is stored as the stop mark position 39. If stop mark 2 is not detected, a stop mark error is generated (step 34), and the process branches to retry processing (step 104).

When both the start mark 1 and the stop mark 2 are detected, a data analysis process is performed next (step 31). First, the head position 40 of the bit mark in the data part is calculated from the start mark position 37 and the stop mark position 39. At this time, due to the difference between the calculated value of the distance between the start mark position 37 and the stop mark position 39,
The head position 40 is corrected.

From the head position 40 obtained in this way,
The average value of 8-bit data having a width 41 of each bit mark;
Comparing the average value of the 8-bit de <br/> over data width 42 space the same width immediately followed. Taking the difference between the average value and the average value of the space immediately thereafter the bit marks, stores the result of 1 is greater than the bit mark determination threshold, a 0 is smaller than the threshold, the decoding result storage area 43 I do.

When the decoding process (Step 102) is completed, a parity check is performed to compare the bit-inverted sum of the byte data values stored in the decoding result storage area 43 with the parity byte value (Step 102). 32). If they do not match, a parity error occurs (step 35) and a retry process (step 104)
Branch to If there is no error, the process ends normally.

In the retry process (step 104), first, in a series of processes for reading the ID mark, the retry is performed by further changing the conditions depending on the type of error, the number of times the retry was performed, and what kind of retry was performed. Or
Alternatively, it is determined whether the processing is abnormally terminated as a reading error.

The types of errors include a start mark error (step 33) and a stop mark error (step 3).
4) and parity error (step 35). The following shows how conditions are changed for each error.

A start mark error (step 33) occurs when a start mark serving as a base point of the present processing cannot be found in the print buffer, or when there is no data arrangement corresponding to the start mark. The causes may be the case where the binarization is inappropriate and the case where the left end of the start mark cannot be detected properly due to the floating of the sheet. In the former case, threshold value change processing for binarization is performed, and the processing is restarted from the start mark detection processing (step 29) of the decoding processing (step 102). In the latter case, a stop mark is detected assuming a start mark position and a low-density mode / high-density mode (step 30), and a process for determining the two values from that position is performed. A data analysis process (step 31) is performed.

Stop mark error (step 34)
Is a process for calculating a position of a stop mark in a memory from a start mark position, and searching for a sequence of data corresponding to the stop mark from the vicinity of the stop mark while comparing the data arrangement with a start mark / stop mark detection threshold value. Occurs when it cannot be found. In this case, it is determined that the threshold value for start mark / stop mark detection is inappropriate, the threshold value is changed, and the stop mark detection process (step 30) is executed again.

The parity error (step 35) is based on the ID
This occurs when the sum of the decoding result of the data part of the mark and the result of bit inversion do not match the parity byte. In this case, first, the bit mark determination threshold is changed, and the data analysis process (step 31) is executed again. Further when an error occurs, changes the value of the bit-mer <br/> click the head position of each byte, data analyzing process (Step 3
Re-execute 1).

Although the A / D converter 17 of this embodiment converts the electric signal from the ID mark into an 8-bit digital value, sufficient performance can be obtained, but the A / D converter converts the electric signal to 2 bits or more. Anything that can be used may be used.

[0031]

As described above, according to the ID mark reading apparatus of the present invention, the electric signal from the ID mark is converted into a digital value of 2 bits or more for each fine width, and the digital signal for each bit mark and space for the ID mark is converted. Since the digital values are averaged, and the difference between the digital values and the threshold value are compared to output a decoding result, the reading performance of the ID mark when all the digital values ascend or descend can be improved. Therefore, I cannot be read conventionally.
It can also be read with a D mark.

In the case where the storage means, the judgment means, the retry means and the like are added, if the decoding result is abnormal, the threshold value can be changed and a new decoding result can be output. Since the decoding result is obtained only by software processing without scanning the mark, the reading speed of the ID mark can be improved. Further, there is an effect that various error states can be rescued only by software processing, as compared with the case where binary data is decoded.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of the present invention.

FIG. 2 is a block diagram showing one embodiment of the present invention.

FIG. 3 is a flowchart showing an outline of the entire operation of one embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a digitizing process according to one embodiment of the present invention.

FIG. 5 is a flowchart of a decoding process according to an embodiment of the present invention.

FIG. 6 is an explanatory diagram of start mark detection according to one embodiment of the present invention.

FIG. 7 is an explanatory diagram of stop mark detection according to one embodiment of the present invention.

FIG. 8 is an explanatory diagram of a decoding process according to an embodiment of the present invention.

FIG. 9 is a plan view showing the shape of an ID mark.

[Explanation of symbols]

Reference Signs List 16 light receiving sensor 17 A / D converter 50 ID mark reading device 52 ID mark 54 reflected light from ID mark 56 storage means 58 decoding means 60 determination means 62 retry means M bit mark S space

Claims (2)

(57) [Claims] 1. A bitmer representing a logical 0 or 1.
Position between the mark and the space between the bit marks
I calculated from the position of the mark and stop mark
For the D mark, a light receiving sensor that detects reflected light from the ID mark and converts it into an electric signal for each fine width, and an A that converts the electric signal into a digital value of 2 bits or more.
/ D converter, averages the digital values for each of the bit mark and the space, obtains the difference between the digital value of the space adjacent to the digital value and the corresponding bit mark of the bit marks are those averaging, An ID mark reading device comprising: decoding means for comparing the difference with a threshold value and outputting a decoding result obtained by binarizing the bit mark. 2. A bitmer representing a logical 0 or 1.
The position of the space between the
I calculated from the position of the mark and stop mark
For the D mark, a light receiving sensor that detects reflected light from the ID mark and converts it into an electric signal for each fine width, and an A that converts the electric signal into a digital value of 2 bits or more.
/ D converter, storage means for storing the digital value, and averaging the digital value stored in the storage means for each of the bit mark and the space, and averaging these bit marks. seeking the difference between the digital value of the digital value and the space adjacent to the bit-mer <br/> click,
Decoding means for comparing the difference with a threshold value to output a decoding result obtained by binarizing the bit mark; determining means for determining whether the decoding result is normal; and when the decoding result is abnormal. Retry means for changing the threshold value and outputting the decoding result from the decoding means again.