JPH06251183A - Bar code reader and bar code display medium used in the same - Google Patents

Abstract

PURPOSE:To surely read a bar code even when bar code scanning speed is remarkably fluctuated without increasing the number of synchronous bars. CONSTITUTION:A counter part 12 measures a time in accordance with bar width every bar corresponding to high/low level signals outputted corresponding to a bar on a bar code display medium 1 and space from a photoelectric conversion part 11, and a reading timing calculation means 15 calculates the reading timing of the output signal level of the photoelectric conversion part 11 to discriminate whether the next bar is a wide bar or a narrow bar at every case from the count value of the counter and a discriminated result whether a measured bar is the wide bar or the narrow bar, and a bar width discrimination means 14 reads the signal level at a calculated timing, then, the wideness/ narrowness of the bar is decided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bar code reader for reading a bar code displayed on a bar code display medium, converting the read information into a signal which can be processed by a computer, and outputting the signal. The present invention relates to a barcode display medium.

[0002]

2. Description of the Related Art Conventionally, there is a bar code reading apparatus which judges whether a displayed bar is a wide bar or a narrow bar and outputs the judgment result as bar code reading information. An example of a bar code display medium that can be inserted into such a device to read bar code information is a card-shaped medium as shown in FIG.

In this bar code display medium 1, a plurality of bar codes are displayed by printing on one side edge of one surface, and the bar code is 1 along the reading direction of arrow A.
One synchronization bar 2 and a data bar 3 consisting of multiple bars
And a check bar 4.

The synchronizing bar 2 determines whether each bar after the data bar 3 arranged in the reading direction is a wide bar having a wide width or a narrow bar having a narrow width.
The data bar 3 is a wide bar used to determine the timing of reading the output signal level of the photoelectric conversion unit, which will be described later. The data bar 3 has a wide bar similar to the synchronization bar 2 and a wide bar 3w and a narrow bar. The narrow bar 3n is arranged in a required order and combination, and the check bar 4 is a wide bar used to confirm the correctness of the read information. This barcode display medium 1 is
When the bar is inserted into the bar code reader and the bar portion is scanned, the information displayed thereon is sequentially read.

The bar code reading device for reading the bar code display medium 1 inserted in the bar code display medium 1 along the reading direction (direction indicated by an arrow A in FIG. 3) by a photoelectric conversion unit having a reflection type photo sensor 5, for example. By scanning, the bars that make up the bar code and the space between them are converted into high / low level signals, and it is sequentially determined whether each bar is a wide bar or a narrow bar, and that is used as bar code reading information. Output.

Whether the read bar is a wide bar or a narrow bar is determined by the following method, for example. Bar code display medium 1 shown in FIG.
Is conveyed in the direction opposite to the arrow A, the photosensor 5 of the photoelectric conversion unit scans the bar array shown in FIG. 4A to scan the level signal shown in FIG. 4B (actually a binarized signal). ) Is output. At that time, the bar width Wb in the reading direction of the first synchronization bar 2 is measured by counting the clock signal,
The count value (time) Ta is obtained.

The count value Ta of the synchronizing bar 2 determines the timing at which the output signal level of the photoelectric conversion unit is read in order to determine whether the data bar 3 is a wide bar or a narrow bar. For example, as shown in (b) to (d) of FIG. 4, (3
/ 4) At the timing (count value) after Ta, the signal level of the photoelectric conversion unit output is read, and if it is a high level “1”, it is determined to be a wide bar, and if it is a low level “0”, it is determined to be a narrow bar. It was

[0008]

However, each bar width of the data bar is a wide bar on the basis of the reading time Ta corresponding to the bar width of the synchronization bar positioned at the beginning in the bar code reading direction. If the reading timing of the output signal level of the photoelectric conversion unit for reading whether it is a narrow bar or a narrow bar is determined, the conveyance speed of the barcode display medium fluctuates significantly, or the photoelectric conversion unit side of the barcode reading device is moved. In the case of the configuration, if the movement speed of the photoelectric conversion unit fluctuates greatly, there is a problem that the wide / narrow of each bar of the data bar cannot be accurately determined.

That is, in the case of a data bar displayed at a position relatively close to the sync bar, the transport speed or moving speed when the data bar is read is almost the same as the speed when the sync bar is read. There is no problem because it does not change, but especially when the number of data bars is large, the above-mentioned transport speed (or moving speed) during reading may greatly fluctuate with respect to the speed when the synchronous bar is read. In such a case, for example, when a wide bar is used, the high level "1" should be read at the reading timing (3/4) Ta, but the low level "0" is read due to the deviation of the reading timing. There was a risk of making a wrong decision.

Therefore, in order to avoid such an erroneous determination, it may be possible to provide the synchronization bar also at the data bar portion at a predetermined interval. However, if this is done, only the number of synchronization bars increases. The bar code becomes longer, and the area ratio of the bar code on the bar code display medium increases. In addition, the time required for the reading becomes extra, and the processing speed becomes slow.

The present invention has been made in view of the above problems, and changes in the transport speed of the bar code display medium or the moving speed of the photoelectric conversion unit without increasing the number of bars on the bar code display medium. It is an object of the present invention to provide a bar code reader capable of accurately discriminating wide / narrow of each bar of a data bar and reliably reading a bar code even when is large. Another object is to provide a bar code display medium in which the wide / narrow of each bar can be accurately discriminated by the device.

[0012]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention has a bar code bar consisting of a wide bar having a wide bar and a narrow bar having a narrow bar displayed on a bar code display medium, and a space therebetween. And a photoelectric conversion unit that converts and outputs the high and low level signals, a counter unit that measures time, and a counter unit that causes the counter unit to measure the time when the photoelectric conversion unit detects the bar. A counter control unit for controlling, a bar width discriminating unit for discriminating whether the bar detected by the output signal level of the photoelectric conversion unit at the calculated reading timing is a wide bar or a narrow bar, and the bar width discriminating unit. Based on the discrimination result and the count value according to the width of the bar measured by the counter unit, the bar width discriminating means is informed whether the next bar is a wide bar or a narrow bar. A barcode reading device is configured by providing a reading timing calculation unit that calculates the reading timing of the output signal level of the photoelectric conversion unit for differentiating, and the discrimination result by the bar width discriminating unit is output as barcode reading information. It is the one.

Further, in the bar code display medium used in the bar code reading device, a synchronization bar for determining the timing of reading the bar is read at the head of the bar code reading direction, and the correctness of the information read at the end is verified. A bar code display medium that displays check bars for confirmation, displays a data bar composed of multiple wide bars and narrow bars in the required order and combination between them, and has the same bar width for the synchronization bar and the wide bar. I will provide a. Then, in the bar code display medium, it is preferable that the ratio of the bar widths of the wide bar and the narrow bar is 2: 1.

[0014]

According to the bar code reading apparatus thus constructed, the counter section measures the time corresponding to the bar width of each bar according to the high / low level signal output from the photoelectric conversion section, From the count value and the determination result of whether the bar detected by the output signal level of the photoelectric conversion unit at the read timing is a wide bar or a narrow bar,
The reading timing calculation means calculates the reading timing of the output signal level of the photoelectric conversion unit for determining whether the next bar is the wide bar or the narrow bar each time, and the next bar is the wide bar at the calculated timing. The bar width discriminating means discriminates whether it is a narrow bar or a narrow bar.

Therefore, the read timing of the high / low level signal of the photoelectric conversion unit for determining whether each bar is a wide bar or a narrow bar is always the count value of the bar width read immediately before. Since it is decided based on the bar discrimination result, even if the transport speed of the bar code display medium or the movement speed of the photoelectric conversion part is large, the bar code can be accurately discriminated from the wide / narrow of each bar. It can be read reliably.

Further, the bar code display medium used in the bar code reading device displays a sync bar at the beginning of the bar code reading direction, a check bar at the end thereof, and a data bar between them, respectively. If the wide bars have the same bar width, the sync bar with the same width as the wide bar is read first, and the count value corresponding to the bar width is smaller than the count value corresponding to that bar width. By setting the count value larger than the above as the reading timing of the output signal level of the photoelectric conversion unit for determining whether the next bar is a wide bar or a narrow bar, each bar from the first bar of the data bar is read. Wide / narrow can be accurately discriminated.

Further, if the ratio of the bar widths of the wide bar and the narrow bar is set to 2: 1, it becomes easy to determine the timing for determining whether each bar is the wide bar or the narrow bar.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a block diagram showing the construction of an embodiment of a bar code reading apparatus according to the present invention together with a bar code display medium used for it, and FIG. 2 is a timing chart for explaining its operation.

In the bar code reading apparatus shown in FIG. 1, the bar of the bar code displayed on the bar code display medium 1 is composed of a wide bar 3w having a wide width and a narrow bar 3n having a narrow width, and a space between them is set to high / low. Photoelectric conversion unit 11 including photosensor 5 for converting to a low level signal and outputting the signal
And a counter section 12 for measuring time and a photoelectric conversion section 11
A counter control unit 13 that controls the counter unit 12 so that the counter unit 12 measures the time during which the bar is detected by counting the number of clock pulses generated internally.
And are provided.

The reading timing calculation means 1 described later
A bar width discriminating means 14 for discriminating whether the detected bar is a wide bar or a narrow bar, and a discrimination by the bar width discriminating means 14 according to the output signal level of the photoelectric conversion unit 11 at the read timing calculated by 5. The output signal level of the photoelectric conversion unit 11 for causing the bar width determination unit 14 to determine whether the next bar is a wide bar or a narrow bar based on the result and the count value according to the width of the bar measured by the counter unit 12. There is provided a read timing calculation means 15 for calculating the read timing of the bar and a memory (register) 16 for storing the calculated read timing and information such as whether the read bar is a wide bar or a narrow bar. Save the discrimination result by the discriminating means 14 in the memory 16 and output it as bar code reading information. It is.

On the other hand, the bar code display medium 1 has one synchronization bar 2 for determining the bar reading timing at the beginning of the bar code reading direction, followed by data consisting of a plurality of wide bars 3w and narrow bars 3n. Bar 3
A check bar 4 for confirming the correctness of the information read at the end is displayed by printing on one side edge side of one surface, and the wide bar 3w and the narrow bar 3n are displayed.
The ratio of the bar width in the reading direction is 2: 1, and the bar width of the wide bar 3w and the bar width of the synchronization bar 2 and the check bar 4 are the same.

This bar code display medium 1 is inserted into the bar code reader having the structure shown in FIG. 1 and moved in the direction of arrow B, or the photoelectric conversion unit 11 side is moved. 2A, at least the photo sensor 5 is moved in the direction opposite to the arrow B, and
When you scan a bar code as shown in, the high (“1”) / bar width depends on the bar width and space width of each bar in the reading direction.
A low (“0”) output signal “1” is output from the photoelectric conversion unit 11 with a waveform as shown in FIG. Note that the photoelectric conversion unit 11 inverts the photoelectric output from the photosensor 5 and binarizes it.

The counter control unit 13 shown in FIG. 1 monitors the output signal of the photoelectric conversion unit 11, detects the tip 2a of the synchronization bar 2 shown in FIG. When it is confirmed that it has risen from "0" to "1", it causes the counter unit 13 to start counting clock signals, and continues to monitor the output signal after that, and when the output signal falls from "1" to "0". , Count value at that time (time) T
Store a1 in the memory 16.

The count value Ta1 is a value indicating the time corresponding to the bar width of the synchronizing bar 2 in the reading direction. next,
The read timing calculation means 15 calculates (3/4) Ta1 from the count value Ta1 by calculation, and stores the calculation result in the memory 16 as the read timing of the output signal. At this time, the counter control unit 13 continues to monitor the output signal output by the photoelectric conversion unit 11.

When the photoelectric conversion unit 11 detects the tip of the next wide bar 3w (which may be the narrow bar 3n depending on the bar code) and the output signal rises, counter control is performed. The unit 13 resets and restarts the counter unit 12 (reset / start), and continues to monitor the output signal thereafter.

Then, the bar width discriminating means 14 compares the count value (time) of the counter section 12 with (3/4) Ta1 indicating the reading timing stored in the memory 16, and the count value is (3 / 4) When Ta1 is reached, the output signal level (“0” or “1”) of the photoelectric conversion unit 11 is read.

In the case of the example shown in FIG. 2, since the data bar next to the synchronization bar 2 is the wide bar 3w having a wide bar width, the bar width discriminating means 14 reads the high level "1". The bar read at that time is determined to be a wide bar, and the determination result is stored in the memory 16.

After that, the counter section 12 continues to count the clock signal, and when the output signal of the photoelectric conversion section 11 falls from "1" to "0", the count value Ta2 of the counter section 12 at that time is stored in the memory 16. To memorize. Then, the bar width determination result (wide bar in this case) stored in the memory 16 and the count value T corresponding to the bar width
The read timing calculation means 15 calculates the next read timing as (3/4) Ta2 based on a2 and stores it in the memory 16.

When the output signal of the photoelectric conversion unit 11 once becomes low level "0" and then rises again to high level "1" (detects the second data bar), the counter control unit 13 makes a counter. The unit 12 is reset and started again, and the monitoring of the output signal of the photoelectric conversion unit 11 is continued.

Then, as in the case of the first data bar, the count value (time) of the counter section 12 is compared with (3/4) Ta2 indicating the second read timing.
Since the second data bar shown in FIG. 2A is the narrow bar 3n this time, the output signal of the photoelectric conversion unit 11 before the count value of the counter unit 12 becomes (3/4) Ta2. Since the low level becomes "0", the count value T at that time
Store a3 in the memory 16.

After that, the counting by the counter section 12 is continued, and when the count value becomes (3/4) Ta2,
The bar width discriminating means 14 reads the output signal level (“0” in this case) of the photoelectric conversion unit 11 at that time, discriminates that the second data bar is a narrow bar, and the discrimination result is stored in the memory 16. Remember. And memory 1
Bar width discrimination result stored in 6 (narrow bar in this case)
And the count value Ta3 corresponding to the bar width, the read timing calculation means 15 calculates the next read timing as (3/2) Ta3 and stores it in the memory 16.

In this way, when the bar immediately before (the one before) is a narrow bar, the read timing of the output signal level of the next photoelectric conversion unit 11 is set to 3/2 of the count time of the bar immediately before. When set to, the ratio of the bar widths in the reading direction of the wide bar 3w having a wide width and the narrow bar 3n having a narrow width is set to 2: 1 as described above, and therefore, from the tip of the bar to be read (position rising to high level). When considering the case of the wide bar 3w as a reference, the timing at which the position is 3/4 from the tip of the bar can be the reading timing of the output signal level of the photoelectric conversion unit 11.

Therefore, regardless of whether the immediately preceding bar is a wide bar or a narrow bar, the photoelectric conversion unit 11 for always discriminating whether the bar is the wide bar or the narrow bar from the tip of each bar at a constant timing. Since the output signal level can be read, it is possible to accurately determine the wide / narrow of each bar.

Then, the reading timing (3/3) calculated by the reading timing calculating means 15 is calculated for each bar.
4) Repeating the process of determining whether the bar is a wide bar or a narrow bar according to the output signal level of the photoelectric conversion unit 11 at Tan or (3/2) Tan by the number of bars forming the barcode. As a result, even if there is a great change in the carrying speed of the bar code display medium, the moving speed (scanning speed) of the bar code reading device has a large change when the photoelectric conversion unit side is moved. Even in this case, the wide / narrow of each bar after the data bar can be accurately discriminated and the bar code can be accurately read.

In the above embodiment, after the photoelectric conversion unit 11 detects the tip of the synchronization bar and the output signal rises, the counter unit 12 is kept in the counting state, and the count value of the output signal rises each time thereafter. However, it is also possible to temporarily stop the counting operation of the counter section 12.

For example, when the output signal at the read timing calculated by the read timing calculating means 15 for each bar is at a high level "1", the counter section is subsequently output when the output signal falls to "0". 12
The count value is stored in the memory 16 to stop the counting, and then the output signal is reset / started when the output signal rises to "1" again, and the output signal at the reading timing is low level "0". In that case, it is possible to stop the counting of the counter section 12 at that time and reset and start when the output signal rises to "1" again.

[0037]

As described above, according to the present invention, the time corresponding to each bar width is measured by the counter by the signal output by the photoelectric conversion unit detecting each bar and space, and the measured count is obtained. The read timing of the output signal level of the photoelectric conversion unit for determining whether the next bar is the wide bar or the narrow bar is determined from the value and the determination result of whether the bar is the wide bar or the narrow bar. Since the wide / narrow of the bar is sequentially determined at that timing, each bar that composes a bar code does not have to be increased even if the scanning speed changes without increasing the number of synchronization bars for determining the bar reading timing. The barcode can be read reliably by accurately discriminating between wide and narrow.

Further, if the bar width of the synchronizing bar and the width of the wide bar in the bar code display medium used in the bar code reading device are made the same, the wide / narrow of the bar next to the synchronizing bar and the bar next to the wide bar can be obtained. The read timing of the output signal level of the photoelectric conversion unit for the determination can be the same, and the wide / narrow of each bar can be accurately determined from the beginning of the data bar.

Further, if the ratio of the bar widths of the wide bar and the narrow bar is set to 2: 1, it becomes easy to determine the timing for determining whether each bar is the wide bar or the narrow bar.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a bar code reading device according to the present invention together with a bar code display medium used therein.

FIG. 2 is a timing chart for explaining the operation of the barcode reading apparatus shown in FIG.

FIG. 3 is a plan view showing an example of a barcode display medium.

FIG. 4 is a timing chart for explaining a bar width determination method in a conventional bar code reading device.

[Description of Codes] 1 bar code display medium 2 synchronization bar 3 data bar 3w wide bar 3n narrow bar 4 check bar 11 photoelectric conversion unit 12 counter unit 13 counter control unit 14 bar width determination unit 15 reading timing calculation unit

Claims (3)

[Claims] 1. A photoelectric conversion device for converting a bar of a bar code composed of a wide bar having a wide width and a narrow bar having a narrow width displayed on a bar code display medium and a space between them into a high / low level signal for output. A conversion unit, a counter unit that measures time, a counter control unit that controls the counter unit so that the counter unit measures the time when the photoelectric conversion unit detects the bar, and the calculated read timing. A bar width discriminating means for discriminating whether the bar detected by the output signal level of the photoelectric conversion portion is the wide bar or the narrow bar, and the discrimination result by the bar width discriminating means and the bar measured by the counter portion. From the count value corresponding to the width of the photoelectric conversion unit for making the bar width determination means determine whether the next bar is a wide bar or a narrow bar. A bar code reading apparatus comprising: a reading timing calculating means for calculating a reading timing of an output signal level, and a discrimination result by the bar width discriminating means is output as bar code reading information. 2. The barcode display medium used in the barcode reading device according to claim 1, wherein a synchronization bar for determining the timing of reading the bar at the beginning of the reading direction of the barcode is read at the end. Check bars for confirming the correctness of the information are displayed respectively, and a data bar composed of a plurality of wide bars and narrow bars in a required order and combination is displayed between them, and the bar widths of the synchronization bar and the wide bar are displayed. A bar code display medium characterized by being the same. 3. The bar code display medium according to claim 2, wherein the ratio of the bar widths of the wide bar and the narrow bar is 2: 1.