JP2742144B2 - Optical reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical reader for reading a bar code printed on a medium such as paper.
In particular, the present invention relates to bar code reading error detection.

[0002]

2. Description of the Related Art In a bar code, characters such as letters and numerals are coded by using a plurality of bars having different widths, so that character columns such as product prices and product names are represented by an array of bars. It was done. A code representing a character is hereinafter referred to as a character code, but the number of bars representing one character code, a thick bar,
Although the combination pattern of the thin bars differs depending on the bar code format, in each case, a bar (margin space), a start code, and a stop code representing a start code and a stop code are respectively provided before and after a row of bars representing all character codes. Rows are provided.

[0003] In the following, for the sake of clarity, the format of the barcode is assumed to be Interleaved 2 of5. In this example, five black bars represent one character, and five white bars at intervals of the black bars represent one character. One bar code represents a plurality of character codes, and each character code represents one digit, and represents a plurality of character codes.

In this type of barcode display, a ground color portion of a medium having a predetermined width on the left side of the barcode display is a start margin, and a ground color portion of a medium having a predetermined width on the right side is a stop margin. The margin is used to determine that the barcode is displayed. The thin bar at the left end of the bar code display and the thin bar following it represent a start code, and the thin bar at the right end and the thick bar to the left of this represent a stop code. A character code for discriminating each display content is provided between the start code and the stop code by a combination of a predetermined number of thin bars or thick bars (black bars) and thin spaces or thick spaces (white bars). Is displayed. Here, assuming that the arrangement direction of the character codes (that is, the direction from the start code to the stop code) is the forward direction, the bar code is generally read in the forward direction, but in the reverse direction. In such a case, the start code is read as if the stop code was a start code and as if the start code was a stop code. Thus, the pattern of the stop code is different, so that the reading direction of the bar code can be determined.

An optical reader for reading such a bar code is called a bar code scanner. Hereinafter, an example of a conventional bar code scanner using a line sensor will be described with reference to FIGS. In the figure, 1 is a signal latch circuit during reading, 2 is an illuminating section, 3 is an optical imaging section, 4 is a one-scan counter, 5 is a media, 6 is a bar code, 7 is a start pulse generating circuit, and 8 is a start pulse generating circuit. A pulse width setting circuit, 9 is a level detection circuit, 10 is a photoelectric conversion unit, 11 and 12 are frequency divider circuits, 13 is an oscillation circuit, 14 is a binarization circuit, 15 is a scan count constant memory, 16 is a scan count counter, 17 is a scanning frequency comparator, 18 is an edge detection circuit, 19 is a timer counter, 20 is a count value memory, 21 is a count value memory control unit, 211 is a margin judgment unit, 212 is a fast throw judgment unit, 213 is an address counter. , 214 an address decoder, 215 a reset circuit, 22 a bit image converter, 23 a character code bit image memory, and 24 a stop code bit. Image memory, 25-bit image memory control unit, 26 a start scan shoulder stop determination unit, 27 Kiyarakuta conversion unit, 28 Kiyarakutakodo match comparator, the error processing circuit 29, 3
0 is a constant memory, 31 is a data coincidence counter, 32
Is a data match number comparator, and 33 is an output data conversion unit.

In FIG. 5, an oscillation circuit 13 is always operating, and its output signal is divided by a frequency dividing circuit 11 to form a clock φ1 and a frequency dividing circuit 12 to form a clock φ2. Is done. The clock φ1 is supplied to the photoelectric conversion unit 10 composed of a line sensor and the one-scan counter 4, and the clock φ2 is supplied to the timer counter 19.

A read start signal S from a host device (not shown)
Is supplied, the reading signal latch circuit 1 is set and outputs a reading signal READ, which is supplied to the illuminating section 2 and the start pulse generating circuit 7. The illuminating section 2 has an LED as a light emitting element, and illuminates the LED in response to a reading signal READ to illuminate the printing area of the bar code 6 on the media 5. The light reflected from the printing area is transmitted to the optical imaging unit 3
The light is irradiated onto the light receiving surface of the line sensor, which is the photoelectric conversion unit 10, and an image of the barcode 6 is formed on the light receiving surface of the line sensor by the optical imaging unit 3. Hereinafter, the photoelectric conversion unit 10 will be described as a line sensor.

The start pulse generating circuit 7 has the following four conditions: (1) the scanning end signal SED is supplied from the one-scan counter 4; and (2) the reading signal from the latch circuit 1 during reading.
(3) The pulse width setting is completed in the pulse width setting circuit 8 and the set value is sent. (4) The character conversion end signal CED is supplied from the character converter 27. Are simultaneously satisfied, a start pulse ST is generated. Such a condition is hereinafter referred to as a pulse generation condition.

In the initial state, the one-scan counter 4 has set the scan end signal SED, the pulse width setting circuit 8 has set the initial value, and the character converter 27 (FIG. 6) has the character conversion end signal CED. The start pulse generating circuit 7 satisfies the pulse generating condition when the reading signal READ is supplied from the reading signal latch circuit 1 and the start of the pulse width determined by the initial value of the pulse width setting circuit 8 is started. A pulse ST is generated. The start pulse ST is supplied to the one-scan counter 4 and the line sensor 10. The line sensor 10 reads the image of the light receiving surface one pixel at a time when the clock φ1 is supplied by the start pulse ST, and scans and reads the bar code 6. As a result, the line sensor 10 outputs electric signals having different levels between the black bar and the white bar of the bar code 6.
The one-scan counter 4 starts counting the clock φ1 in response to a start pulse ST, and outputs a scan end signal SED.
Is stopped, and when the clock φ1 for one scan of the line sensor 10 is counted, the scan end signal SED is output again. The scanning end signal SED is supplied to a start pulse generating circuit 7, a scanning counter 16 and a count value memory 2.
0, margin determination circuit 211 and address counter 2
13 is supplied.

The pulse width of the start pulse ST determines the charging time of each capacitor forming a pixel in the line sensor 10, and the line sensor 10 according to the charging time.
The magnitude of the level of the output signal is determined. The output signal is supplied to a level detection circuit 9 where the level is detected, and a pulse width setting circuit 8 sets a pulse width to an optimum level according to the detection result. The start pulse generating circuit 7 again generates a start pulse ST having a pulse width corresponding to the set value of the pulse width setting circuit 8 when the scan end signal SED is supplied again from the one-scan counter 4 and the pulse generation condition is satisfied. The line sensor 10 starts scanning, and the one-scan counter 4 starts counting.

As described above, the line sensor 10 repeatedly scans the bar code 6.

The output signal of the line sensor 10 is binarized by a binarization circuit 14 and then an edge detection circuit 18
The rising and falling edges are detected. The edge pulse EG output from the edge detection circuit 18 is supplied to a timer counter 19 and an address counter 213.

The timer counter 19 counts the clock φ2 from the frequency dividing circuit 12 using the edge pulse EG as a reset signal. Accordingly, the count value N representing the width of each bar of the bar code 6 is output from the timer counter 19. The count value N is written to the count value memory 20 controlled by the count value memory control unit 21.

The count value memory control unit 21 includes a margin judgment unit 211, a first throw judgment unit 212, an address counter 213, an address decoder 214, and a reset circuit 215. The margin determining unit 211 counts the count value N of the timer counter 19 with respect to blank portions (start margin, stop margin) provided before the head bar and after the last bar of the barcode 6;
By the ratio of the blank part and the bar code part count value,
The start and end of the barcode are detected, and a start signal MST and an end signal MED are generated. When the start margin and the stop margin are insufficient, a margin error signal MER is output and supplied to the reset circuit 215. When the scanning end signal SED is supplied from the one-scan counter 4, the margin determination circuit 211 does not operate. The first throw determination unit 212 is a timer counter 1
9 is detected, and when the interval of the edge pulse EG from the edge detection circuit 18 is too narrow or too wide, a fast slow error signal is output and supplied to the reset circuit 215. I do. When the bar code 6 is printed on the media 5 and the bar is narrowed or spread due to bleeding, scratching or dust adhesion, the first throw determination unit 212 outputs a first slow error signal. I do. The reset circuit 215 generates a reset signal and counts with the address counter 213 when the margin error signal MER is supplied from the margin determination section 211 or when the first throw error signal is supplied from the first throw determination section 212. To the value memory 20.

When the line sensor 10 starts scanning without supplying the scan end signal SED from the one-scan counter 4, the address counter 213 sets the margin judgment unit 21
The start signal MST is supplied from 1 and the edge signal EG from the edge detection circuit 18 starts counting from the initial value. The count value output from the address counter 213 is decoded by the address decoder 214 and supplied to the count value memory 20 as an address signal ADR. When the scan end signal SED is no longer supplied from the one-scan counter 4, the count value memory 20 enters the write mode, and the count value N output from the timer counter 19 is stored in the address specified by the address signal ADR of the count value memory 20. Written sequentially.

When the count values N for all the bars of the bar code 6 are written to the count value memory 20 and the end signal MED is output from the margin judgment unit 211, the address counter 213 stops counting and the initial value is set. Is done. Next, after one scan of the line sensor 10 is completed, 1
When the scan counter 4 outputs the scan end signal SED, the count value memory 20 enters the read mode, and the address counter 213 outputs a count value sequentially incremented by one from the initial value by the internal clock. This count value becomes the address signal ADR of the count value memory 20 by the address decoder 214. Therefore, the written count value N is read from the count value memory 20.
Are read out in the order in which they were written.

When the reset circuit 215 outputs a reset signal, the address counter 213 is reset to an initial value and the count value memory 20 is cleared. The margin judging section 211 continues to output the margin error signal MER until the next margin judgment, and the first throw judging section 212 outputs the first slow error signal until the next scanning end signal SED is supplied from the one-scan counter 4. to continue.

The count value N output from the count value memory 20 is supplied to a bit image converter 22, where it is compared with a preset threshold value and converted into a bit image BI representing the type of bar.

Next, FIG. 6 will be described. The bit image BI from the bit image conversion unit 22 is supplied to a character code bit image memory 23, a stop code bit image memory 24 and a bit image memory control unit 25. Bit image memory control unit 25
Determines whether the bit image BI is a character code bit image (character code bit image) or a stop code bit image (stop code bit image) by determining the output order of the bit image BI. Identify and bit image B
When I is a character code bit image,
The bit image BI is divided into five pieces each to form 1-byte data, and these data are sequentially written into the character code bit image memory 23, and the bit image BI is written.
Is a stop code bit image, this is written to the stop code bit image memory 24.
In the case of the interleaved 2of5, the bit images for the black bar and the white bar are divided, and 1-byte data is formed for each, and written to the character code bit image memory 23. When the writing in the character code bit image memory 23 and the stop code bit image memory 24 is completed, the bit image memory control unit 25 sequentially reads the one-byte data CCD from the character code bit image memory 23 and reads the character CCD. The stop code bit image SCD is read from the stop code bit image memory 24 and sent to the start stop determination unit 26.

In the start stop judging section 26,
For the correct stop code used for barcodes,
Bit patterns (hereinafter referred to as registered stop code patterns) of two types of bit images obtained when the image is correctly read in the forward and reverse directions are registered in the ROM.
A bit pattern of the data SCD with one bit image (hereinafter, referred to as a detected stop code pattern) is compared with a registered stop code pattern, and it is determined which registered stop code pattern matches. When there is a registered stop code pattern that matches the detected stop code pattern, the reading direction of the bar code 6 can also be determined based on the registered stop code pattern, and data (stop code data) corresponding to the matched registered stop code pattern can be determined.
The SSC is supplied to the output data converter 33, and the conversion direction instruction signal CDD is sent to the character converter 27.

When there is no registered stop code pattern matching the detected stop code pattern SCD, the start stop judging section 26 outputs an error signal ERR 1 and supplies it to the error processing circuit 29.

In the character conversion unit 27, for all character codes used for bar codes, a bit pattern (hereinafter, referred to as 1 bit data) including a bit image obtained when correctly read in the forward direction.
A registered character code pattern is registered in the ROM, and the character code bit image memory 2 is stored in the ROM.
The bit pattern of the 1-byte data CCD from 3 (hereinafter referred to as a detected character code pattern) is compared with the registered character code pattern to determine which registered character code pattern matches. In this case, when the bar code 6 is read in the reverse direction, the detected character code pattern CCD is output by the conversion direction instruction signal CDD from the start stop determination unit 26.
Is reversed and compared with the registered character code pattern.

When the detected character code pattern CCD matches any of the registered character code patterns,
The character conversion unit 27 outputs character data CD corresponding to the registered character code pattern that matches, and sends it to the character code match comparator 28 and the output data conversion unit 33. When the detected character code pattern CCD does not match any of the registered character code patterns, the character converter 27 generates an error signal ERR2 and sends it to the error processing circuit 29. When all the detected character code patterns CCD for one scan of the bar code 6 are converted into character data CD, the character converter 27 generates a character conversion end signal CED to generate a character conversion end signal CED.
Is supplied to the start pulse generating circuit 7. This allows
The start pulse generating circuit 7 generates a start pulse ST, and the line sensor 10 (FIG. 5) scans the bar code 6 next.

The character code coincidence comparator 28 outputs the character data CD for one scan from the character converter 27.
Is compared with the character data CD supplied from the character converter 27 in the next scan.
When all character data match, a match pulse is output and supplied to the data match counter 31. The data coincidence counter 31 counts the coincidence pulse, and the count value is compared with the coincidence number set value stored in the constant memory 30 by the data coincidence number comparator 32. When the count value of the data match number counter 31 becomes equal to or greater than the set value of the number of match times, the data match number comparator 32 generates a read completion signal REND1 and outputs
Send to Character converter 27 for previous scan and current scan
If even one of the character data CDs from
The character code match comparator 28 outputs the error signal ERR3.
Is output to the error processing circuit 29 and the data coincidence circuit counter 31 is cleared.

The output data conversion unit 33 captures the character data CD from the character conversion unit 27 and the stop code data SSC from the start stop determination unit 26 every time the bar code 6 is scanned, and holds the latest data. When the read completion signal REND1 is supplied from the data match number comparator 32, the held character data CD and stop code data SSC are converted into a predetermined format and sent to a host device (not shown). . At the same time, a display instruction signal DIS for displaying the end of reading is sent to a display device (not shown) such as a lamp or a buzzer, and a reset signal RST is generated to initialize itself. This reset signal RST is supplied to the reading signal latch circuit 1 (FIG. 5) and the like, and resets them. When the reading signal latch circuit 1 is reset by the reset signal RST, it does not output the reading signal READ, and stops reading the bar code 6. The illumination unit 2 is also turned off.

In this manner, when the character data obtained by the preceding and following scans continuously matches the number of times (for example, twice) according to the predetermined number of times set in the constant memory 30, the reading is terminated assuming that the bar code 6 has been correctly read. If the reading does not match this number of times, the reading of the bar code 6 is repeated. However, even if the reading is repeated a certain number of times, the reading completion signal REND from the data matching number comparator 32 is returned.
If 1 is not output, further reading of the bar code 6 is prohibited.

That is, in FIG. 5, the scanning counter 16 counts up by one each time the one-scan counter 4 outputs the scanning end signal SED. The count value of the scan number counter 16 indicates the number of scans of the line sensor 10.
Is compared with the constant set in. When the count value of the number-of-scans counter 16 becomes equal to or greater than this constant, the number-of-scans comparator 17 outputs a read end signal REND2 and supplies it to the output data converter 33 in FIG.

Therefore, the output data converter 33 outputs a reset signal RST to initialize itself without sending character data or stop code data to the host device. As a result, the reading of the barcode 6 is stopped assuming that the reading of the barcode 6 has failed. Also,
A display instruction signal DIS indicating that reading is impossible is sent to the display device.

The error processing circuit 29 outputs the error signal ERR
1, ERR2 or ERR3 is supplied, the character conversion reset signal CERT is output, and the count value memory control unit 21, bit image conversion unit 22 in FIG. 5, character code bit image memory 23 in FIG. A top code bit image memory 24, a bit image memory control unit 25, a start stop determination unit 26, a character conversion unit 27, and the like are initialized. As a result, the character conversion unit 27 outputs a character conversion end signal CED.

As described above, the line sensor 10 reads and scans the bar code 6 a plurality of times, and when the character codes match continuously the number of times equal to the set value of the number of matches in the constant memory 30, the bar code 6 is correctly read. It is assumed that the reading has been performed, and this character code is sent to the host device to complete the reading operation.

[0031]

By the way, the bar code scanner using the line sensor as described above is used for various types of bar code scanners by changing the registered character code pattern in the character converter 27. Applicable to code. Since the size of the scanning range on the media of the line sensor when the barcode scanner is touched to the media is constant, it is possible to read a barcode that falls within this scanning range, but the size of the barcode is Is not constant and varies in size depending on how it is used. When the same type of barcode scanner as described above is used for reading barcodes that are used in various ways, there is no problem if only one barcode enters the scanning range of the line sensor. However, when a large number of small barcodes are listed as in a TV program guide and a desired barcode is read from this table, two or more barcodes enter the scanning range of the line sensor or two or more barcodes are read. The scanning range of the line sensor may be set across codes, and in such a case, the following problem occurs. However, in the following description, in FIG. 5, the scanning range of the line sensor 10 is the size of two bar codes.

(1) When it is desired to read a desired one of a large number of bar codes, the bar code scanner is touched to the media so that the desired bar code falls within the scanning range of the line sensor. Let it.

Therefore, assuming that the bar code to be read is bar code A, as shown in FIG. 7, the desired bar code A is entirely within the scanning range of the line sensor 10, but the adjacent bar code B is partially. In some cases, the data may be out of the scanning range. In such a case, in FIG. 5, the line sensor 10 reads the barcode A, the margin determination unit 211 generates a start signal MST, the address counter 213 starts counting, and the barcode A is stored in the count value memory 20. The count value N of the timer counter 19 for A is stored. However, when the line sensor 10 starts reading the barcode B next time,
Margin determining section 211 generates start signal MST again,
The address counter 213 starts counting, and the count value memory 20 rewrites the bar code B with the count value N of the timer counter 19. But,
Since a part of the barcode B is out of the scanning range of the line sensor 10, the barcode B is not rewritten in the count value memory 20 for this part. Therefore, the count value for the barcode B and the count value N for the barcode A are mixed in the count value memory 20.

When the count value N of the count value memory 20 is decoded by the bit image conversion or the character conversion as described above, an error generally occurs. Despite being read so that it can be decoded correctly, a decoding error occurs.

(2) As shown in FIG. 8, when the barcodes A and B are both within the scanning range of the line sensor 10 as a whole, the timer counter 19 for the barcode B that is not desired is stored in the count value memory 20. Only the count value N is stored and decoded, which means that an erroneous bar code has been read.

(3) In order to prevent this, the address counter 213 is operated by the start signal MST from the margin judgment section 211 and then stopped by the end signal MED from the margin judgment section 211, so that the one-scan counter 4 It is conceivable not to respond to the start signal MST from the margin judging unit 211 until the signal is cleared by the scanning end signal SED. According to this, in the case of FIGS. 7 and 8, the count value N of the timer counter 19 is not written into the count memory 20 for the barcode B, and the barcode A is decoded.

However, the quality of the barcode A is poor due to blows, chips, voids or small contrast, and the margin determination unit 211 does not generate the start signal MST even if the line sensor 10 reads the barcode A. In such a case, the address counter 2
13 is not counted, and the count value N for the bar code A is not written in the count value memory 20. Then, when the margin determination unit 211 generates the start signal MST when the line sensor 10 reads the bar code B next, the address counter 213 starts counting, and the count value of the timer counter 19 for the bar code B is stored in the count value memory 20. Since the value N is written, the problems described in the above (1) and (2) occur.

As described in the above (2) and (3) with reference to FIG. 8, when decoding of the bar code B read erroneously is performed, the output data conversion unit 33 of FIG. Ractor data will be sent,
The host device performs an erroneous process that is not desired by the user. For example, it is conceivable to make a program reservation by reading a bar code from a television program table using a bar code as described above. In such a case, the bar code of the data such as the channel number, date and time is determined in a predetermined order. However, if the barcode is read as described above, the order may be out of order. In this case, the host device reads and processes the character data and displays the result as it is. Therefore, the user must confirm this display and correct any errors, which degrades input efficiency and places a heavy burden on the user.

(4) In order to eliminate this inconvenience, error prevention processing has conventionally been performed on the host device side.
For example, as shown in FIG. 7 and FIG.
B is different data such as a channel number and a date, so that the number of characters of these characters and the characters and numbers used are different, and the character data of each data is transmitted in an order determined by the host device. It is determined whether or not it has been received and displayed.

However, according to this, although erroneous input and erroneous operation in the host device can be prevented, display of the output data of FIG. 6 by the bar code scanner decoder by the display signal DIS output from the converter 33 is normal. On the other hand, a defect is displayed on the host device side, and this difference in display causes confusion to the user.

(5) In addition, by the time the bar code is read and the host device performs the above display, (the time from bar code reading by the bar code scanner to decoding) + (character data data) It takes a long time of (transfer time to the host device) + (the determination processing time in the host device), which, together with the situation (3) above, disturbs the rhythm of the barcode reading operation and makes the user tired. This increases unnecessary feelings and burdens the user with unnecessary work and psychological burden.

An object of the present invention is to solve such a problem.
An object of the present invention is to provide an optical reading device capable of quickly detecting an erroneous bar code reading and reducing a user's work load.

[0043]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention reads a specific range of one bar code in a scanning range of a line sensor of a plurality of bar codes. First means for determining whether or not the scanning position of the line sensor is within a reading range, and a timer counter for a bar code starting from within the reading range based on the determination result of the first means. Means for writing the count value in the count value memory.

[0044]

The line sensor performs reading scanning over the entire scanning range. By the first and second means, only the count value for a bar code having a start point in the reading range is stored in the count value memory. Written and decoded. Therefore, if at least the starting point of the desired barcode is positioned in the reading range, the desired barcode is reliably decoded unless a reading error occurs, and other unwanted barcodes can be used instead. It will not be decoded.

[0045]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are block diagrams showing one embodiment of an optical reading apparatus according to the present invention, wherein 6A and 6B are bar codes,
34 is a constant memory, 35 is a read range comparator, and 216 is a switch. The same reference numerals are given to the portions corresponding to FIGS.

In FIG. 1, the scanning range of the line sensor 10 is a size including n bar codes on the media 5 (where n is an integer of 2 or more, and hereinafter, n = 2). is there. In this scanning range, a range corresponding to one barcode is set as a reading range, and the upper and lower limits of the count range of the one-scan counter 4 when the line sensor 10 scans the reading range are set as reading range setting values. Constant memory 34
Is stored in

When the reading scan of the line sensor 10 is started, the one-scan counter 4 counts the clock φ1 from the frequency dividing circuit 11, and the count value of the one-scan counter 4 and the reading range setting value of the constant memory 34 correspond to the reading range. Comparator 3
5 is compared. The reading range comparator 35 is at a high level when the count value of the one-scan counter 4 is between the lower limit and the upper limit of the reading range setting value (when the scanning position of the line sensor 10 is within the reading range). When the value is not between the upper limit and the lower limit of the reading range setting value (line sensor 10
(When the scanning position is out of the reading range), the detection signal RRC which becomes low level is output. Count value memory control unit 21
In the above, the start signal MST output from the margin determination unit 211 is supplied to the address counter 213 via the switch 216, and the switch 216 is controlled by the detection signal RRC from the read range comparator 35. It turns on when the detection signal RRC is at a high level, and turns off when it is at a low level.

Therefore, assuming that the scanning range of one bar code in the first half of the scanning range of the line sensor 10 is the reading range, if at least the front part of one bar code 6A on the media 5 is within this reading range, Start signal M output from margin determination section 211 together with reading of code 6A
The timing of ST is within a period in which the switch 216 is on, and the start signal MST is supplied to the address counter 213 via the switch 216. Therefore,
The address counter 213 counts the edge signal EG, and the count value N of the timer counter 19 for the entire bar code 6A is written in the count value memory 20.

In this case, the next bar code 6B is always outside the reading range, and the line sensor 10
When scanning B, the switch 216 is off,
Even if the margin determination unit 211 generates a start signal MST for the barcode 6B, the start signal MST is not supplied to the address counter 213.

Accordingly, as shown in FIGS. 3 and 4, the front signal of the bar code 6A is within the reading range, and the start signal MST from the margin judging unit 211 by reading the bar code 6A is the signal of the switch 216. If the bar code 6A is in the ON period, the count value N of the timer counter 19 for this bar code 6A is always written to the count value memory 20, and a decoding process is performed. The barcode 6B other than the barcode 6A is not decoded regardless of whether the barcode 6A is read.

In this way, by ensuring that at least the front part of the desired bar code to be read is within the set reading period, the reading and decoding processing of only the desired bar code can be reliably performed. Line sensor 1
If 0 reads and scans a plurality of barcodes, or if there is an error in reading a desired barcode, it will not read and decode the wrong barcode.
Therefore, the bar code is always read and decoded correctly.

[0052]

As described above, according to the present invention,
Even if the line sensor reads and scans a plurality of barcodes, only the desired barcode is read and decoded at all times, so that a malfunction of reading and decoding another barcode by mistake can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a part of an embodiment of an optical reading apparatus according to the present invention.

FIG. 2 is a block diagram showing a portion following the portion shown in FIG. 1 in one embodiment of the optical reading device according to the present invention.

FIG. 3 is a diagram showing one operation of reading a bar code in the embodiment shown in FIGS. 1 and 2;

FIG. 4 is a diagram showing another operation of reading a barcode in the embodiment shown in FIGS. 1 and 2;

FIG. 5 is a block diagram showing a part of an example of a conventional optical reading apparatus.

FIG. 6 is a block diagram showing a portion subsequent to the portion shown in FIG. 5 of an example of the conventional optical reading device.

FIG. 7 is a diagram showing one operation of reading a bar code in the conventional technique shown in FIGS. 5 and 6;

8 is a diagram showing another operation of the bar code reading in the conventional technique shown in FIGS. 5 and 6. FIG.

[Description of Signs] 4 1 Scan Counter 5 Media 6A, 6B Bar Code 10 Line Sensor 19 Timer Counter 20 Count Value Memory 211 Margin Judgment Unit 213 Address Counter 216 Switch 34 Constant Memory 35 Reading Range Comparator

Claims (1)

(57) [Claims] 1. A line sensor which has a scanning range for a plurality of bar codes printed on a medium, scans the scanning range and reads the bar code, and binarizes an output signal of the line sensor. An edge detection circuit for detecting an edge of the binarized signal obtained as described above and generating an edge signal; a timer counter for counting a clock for each edge signal and generating a count value corresponding to a bar width of the bar code; An optical reading device comprising: a count value memory for storing the count value; and decoding the count value stored in the count value memory to generate the bar code character data read. And determining whether the scanning position of the line sensor is within the reading range by setting a specific range for one bar code in the scanning range as the reading range. First means, the beginning of the bar code read by the line sensor
The round part to the count value generated by the timer counter.
A second means for detecting the start position of the line sensor and generating a start signal based on the scanning position of the line sensor.
During the period in which the position is within the reading range,
The timer counter in response to the start signal generated by the timer counter
The count value for one barcode generated in
And a third means for writing the data in the scan value memory , wherein a plurality of barcodes included in the scanning range of the line sensor are read from the head or end within the reading range.
An optical reading device wherein only one barcode to be read can be decoded.