JPH0765104A - Bar code reader - Google Patents

Abstract

PURPOSE:To shorten the decoding time of bar code information by storing no unnecessary information. CONSTITUTION:After a card on which bar code symbol are recorded is passed through a slit, a line sensor 24 picks up an image of the bar code symbols and width information on the bar code symbols is obtained by a bar/space width count part 38 from the output of the line sensor 24 and latched in a latch 40. At this time, a speed detection part 58 detects the moving speed of the card and a line control 42 writes the width information, latched in the latch 40, in a first-in first-out(FIFO) memory 44 on the basis of the moving speed of the card detected by the speed detection part 58 so as to obtain a specific frequency of writing per line of the bar code symbols.

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 symbol from a recording medium on which a bar code symbol is recorded, and more particularly to reducing the decoding time of the bar code symbol by eliminating unnecessary reading. .

[0002]

2. Description of the Related Art At present, bar code symbols are used in many countries, and the types thereof are very large. Typical bar code symbols are JAN / UPC / EAN code, ITF (interleaved 2 of 5) code, and CODE.
There are one-dimensional bar code symbols such as 39, NW-7 code, CODE128, etc. Further, recently, two-dimensional bar code symbols having a large amount of information and a high recording density have begun to be proposed due to a demand for expressing more information, attaching to a narrower space, and the like. Examples of such a two-dimensional barcode symbol include CODE16K and CODE4.
9, PDF417, DATA CODE, etc.

Various types of bar code readers for reading and decoding bar code symbols are known, and as the reading means in those bar code readers, scanning by laser, line sensor or area is used. Means such as imaging with a sensor are widely used.

Specifically, in the laser system, the laser beam spot is scanned on a bar code symbol, and the intensity of reflected light from within this spot is detected in time series. Further, in the line sensor or the area sensor, a bar code symbol image is formed on these sensors using an optical system, and the light amount information detected by each element of the sensor is read out serially.

The data detected in time series or read serially are usually stored by a memory device. For example, in Japanese Unexamined Patent Publication No. 4-256085, a configuration as shown in FIG. 8 is adopted. In the bar code reading apparatus disclosed in this publication, the data read by the bar code detecting section 1 is stored in the data storing section 2 using a first-in first-out (hereinafter referred to as FIFO) memory, and at the same time, the bar code is read. The recognition unit 3 detects the bar code data group, and the address of the bar code data group stored in the data storage unit 2 is stored in the address storage unit 4. In this case, since the FIFO memory is used for the data storage unit 2, the address value is the number of clocks from the reset. The bar code demodulation unit 5 reads the bar code data from the data storage unit 2 using the address stored in the address storage unit 4 and performs demodulation processing.

In the case of a bar code reader using a line sensor, in order to read a one-dimensional bar code symbol, it is sufficient to scan the line sensor, but in order to read a two-dimensional bar code, either the line sensor or the bar code symbol is used. Scanning of the line sensor is repeated while moving in a direction orthogonal to the line sensor.

[0007]

However, when the scanning of the line sensor is repeated while moving the line sensor or the bar code symbol in the direction orthogonal to the line sensor, the moving speed is slow or the scanning of the line sensor is slower than the moving speed. If the speed is high, the same row will be read multiple times and stored in memory. Therefore, in such a case, when decoding the read bar code information, useless information is included, resulting in an increase in decoding time.

The present invention has been made in view of the above points, and an object of the present invention is to provide a bar code reader which shortens the decoding time of bar code information without storing useless information.

[0009]

In order to achieve the above object, a bar code reader according to the present invention has an insertion port for inserting a recording medium on which a bar code symbol is recorded and a recording medium inserted in the insertion port. Scanning means for scanning the recorded bar code symbol, storage means for storing a read signal from the scanning means, speed detecting means for detecting the moving speed of the recording medium inserted in the insertion opening, and the speed detecting means. A control means for writing the read signal from the scanning means into the storage means based on the moving speed of the recording medium detected by the means so that a predetermined number of times of writing per line of the bar code symbol is achieved. It is characterized by having.

[0010]

That is, according to the bar code reader of the present invention, the control means sets the number of times of writing the bar code symbol to the predetermined number of times per line according to the moving speed of the recording medium detected by the speed detecting means. In addition, since the read signal from the scanning means is written in the storage means, it is possible to eliminate unnecessary information storage by scanning the same row a plurality of times.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a block diagram of a bar code reader for reading a two-dimensional bar code PDF417 symbol according to the first embodiment of the present invention. FIG. It is an external view of a system to which a code reader is applied.

As shown in FIG. 2A, in the present system, the bar code symbol 10 is recorded on the card 12, and the bar code symbol is read by passing the card 12 through the slit 16 of the card reader 14. The read information is read by the cable 18 via the host computer 2
Send to 0 and display. At this time, the LED 22 displays whether or not scanning is in progress, whether or not decoding has succeeded.

In the following embodiments, the type of data stored in the memory is described as bar and space width information, but of course, the value obtained by A / D converting the reflected light intensity from the bar code symbol 10 is used. It is also possible to replace it as data to be stored.

The card reader 14 of this embodiment has a structure as shown in FIG. That is, the CCD line sensor 24
An image of the bar code symbol 10 is formed on the upper side using an optical system (not shown). Of course, the line sensor 24 is arranged in the bar and space arrangement direction so that the bar and space widths of the bar code symbol 10 can be read. When the two-dimensional barcode symbol 10 is read using the line sensor 24, the area where the two-dimensional barcode symbol 10 is recorded on the card 12 that can be imaged by the line sensor 24 is moved to read the entire barcode symbol 10. There is a need.

When the card detection unit 26 detects that the card 12 has been inserted, the card detection unit 26 issues a reading start command to start the reading operation. That is, various signals for driving the line sensor 24 are generated by the drive pulse generator 28, and the voltage and current are adjusted by the drive circuit 30, and then input to the line sensor 24.

Due to the black / white color of the bar / space of the bar code symbol 10, there is a difference in the amount of light received by the line sensor 24, and this difference is regarded as a signal in which a voltage difference from the line sensor 24 occurs in time series. Is output. Since this output signal is usually weak, it is amplified by the amplifier circuit 32. And sample and hold (hereinafter, S
/ H) circuit 34 samples the output signal of each pixel of the line sensor 24 near the stable pixel center, and holds the signal level. Next, it is binarized in the binarization circuit 36, and the output signal from this binarization circuit is the bar / space width counter unit 38.
Entered in.

The bar / space width counter section 38 first detects the rising and falling edges of the binarized output signal. The rising and falling portions are the points of the signal that represents the boundary between the bar and the space. Then, the bar / space width counter section 38 measures the time interval of the data from the rising edge to the falling edge and from the falling edge to the rising edge, and uses it as the bar / space width data. The clock used for counting may be a clock synchronized with the clock used for sample and hold in the S / H circuit 34.

The width data thus counted is input to the write control control 42 after being latched by the latch 40. In the write control 42, the input width data is sent to the first-in first-out (hereinafter referred to as FIFO) memory 44 and stored therein. The width data written in the FIFO memory 44 is transferred to the bar code demodulation unit.

In this embodiment, this bar code demodulating unit is
A DSP (Digital Signal Processor) 46 is a main component, and is composed of a program ROM 48, a working RAM 50, and a decoding result output section 52 of the DSP 46. Here, instead of the DSP 46, another microprocessor may be used.

By the way, the FIFO memory 44 uses the FIFO memory 4 in order to read the new data that has been written.
The internal 4 write pointer and read pointer have the following specifications. That is, the write pointer precedes the read pointer and must not pass. Further, depending on the type of the FIFO memory 44, there is one that defines a relative address pointer width of a certain width or more for the read pointer and the write pointer. This is not a problem when the read and write clock speeds are the same, but if the speeds are different, it may happen that the above rules cannot be observed. Therefore, in this embodiment, such pointer management is performed by providing the up / down counter 54 and the pointer management block 56.

A concrete operation example of such pointer management will be described with reference to FIG. The up / down counter 54 is counted up by a write (W) command output from the write control 42 to write data to the FIFO memory 44, and FI
A read (R) instruction for reading data from the FO memory 44 causes a countdown. This allows the FIFO
When one data is written in the memory 44, one pointer is counted up. The counter is cleared by a read start command from the card detector 26. Therefore, the output of the up / down counter 54 becomes the relative address pointer difference between the read pointer and the write pointer inside the FIFO memory 44.

This relative address pointer difference (n) is input to the pointer management block 56. The pointer management block 56 controls the enable / disable of the read / write from the FIFO memory 44 according to the comparison result with the following pointer difference. That is, (B) of FIG.
Then, the read is not performed until the write pointer precedes by the minimum relative address pointer width (min standard) of the standard of the FIFO memory 44. When the count is further counted up and the count output exceeds the minimum relative address pointer width of the standard of the FIFO memory 44 and is less than or equal to the maximum relative address pointer width (max standard) -α of the standard of the FIFO memory 44, a write operation is performed. Lead is performed. Here, α means the expected maximum number of data captured in one scan of the line sensor 24. Further, when the count output exceeds the maximum relative pointer width −α of the standard of the FIFO memory 44 and is less than the maximum relative address pointer width of the standard of the FIFO memory 44, only reading is performed. As a result, when the data from the line sensor 24 is being written in the FIFO memory 44,
The relative address pointer exceeds the maximum relative address pointer width in the standard of the FIFO memory 44 (FIFO
FIFO memory 44, in which the write address pointer inside the memory 44 has caught up with the read address pointer)
It is possible to prevent the problem that writing to the memory has to be stopped in the middle of data for one scan.

Although the FIFO memory 44 is used as the means for storing the width data here, a memory other than the FIFO memory may be used, and depending on the performance of the DSP, the memory is not used and the data is directly sent to the DSP for real-time processing. Also good.

Further, as the data stored in the memory,
As shown in FIG. 3A, the space 10S is connected to the bar 1
The width from the edge that changes to 0B to the next edge under the same condition, the width from the edge that changes from the bar 10B to the space 10S to the next edge under the same condition, such as the width of the adjacent space 10S and bar 10B. A value obtained by adding the widths may be stored. Such a width counter method can deal with the case where the printing accuracy is poor and the width of the bar becomes thicker or narrower than the specified value.

Further, instead of the image signal of the CCD line sensor 24, the reflected light intensity of the scanning laser beam spot may be used. The bar code symbol is read as described above, but the line sensor 2
When a two-dimensional barcode symbol is read by using the barcode symbol 4, the barcode symbol 1 as shown in FIG.
You have to move the card 12 with the 0 written on it. At this time, the line sensor 24 is arranged near the entrance of the slit 16 as shown in FIG. As shown in FIG. 3B, the speed detector 58 of FIG.
Including 0 and the photodiode 62, the moving speed of the card 12 is detected. That is, on both sides of the slit 16, two or more sets of the LED 60 and the photodiode 62 are arranged facing each other along the slit 16. Then, in response to the reading start command from the card detection unit 26, all the LEDs 60 are turned on and the photodiodes 62 are turned on. Thereafter, as the card 12 moves, the light from the LED 60 is blocked by the card 12, and the photodiodes 62 are turned off one after another. The speed detector 58 uses the photodiode 62.
The moving speed of the card 12 is detected from the speed at which the output of turns off. Then, the detected moving speed of the card 12 is sent to the light control 42.

In the two-dimensional barcode PDF417 symbol, a certain aspect ratio is determined with respect to the minimum module width forming the barcode symbol. For example, when the minimum module width is 10 mil and the aspect ratio is (width 1: height 3), 1 in the moving direction of the bar code symbol.
The line length will be 30 mils. From the length of one line in the moving direction of the bar code thus obtained, the scanning speed of the line sensor 24, and the moving speed of the card 12,
The number of scans for scanning one row of the barcode symbol 10 can be calculated. Therefore, in the write control 42, in addition to enabling / disabling the write operation from the pointer management block 56, writing is thinned out at equal intervals from the calculated number of scans per line of barcode, and a certain fixed amount per line of barcode symbol. F to write the number of times
The write enable of the IFO memory 44 is controlled.

In this embodiment, in order to detect the moving speed of the card 12, the LED 60 and the photodiode 62 are used.
In contrast to this, the line sensor 24 is arranged at the position shown in FIG. 3B, but other optical detection means may be used.

In addition, the LED 60 and the photodiode 62
The number and the position with respect to the line sensor 24 may also be configured as shown in FIG. 3 (C) or FIG. 4 (A). That is, in FIG. 3C, a plurality of LEDs 60 and photodiodes 6 are provided before the card 12 reaches the position of the line sensor 24.
2 is arranged, the acceleration is detected together with the speed of the card 12,
By predicting the final speed in the speed detection unit 58, the card 1
The moving speed of 2 is detected. Furthermore, in FIG.
Two sets of the LED 60 and the photodiode 62 are arranged, the speed of the card 12 passing between the two sets of the LED 60 and the photodiode 62 is obtained, and the obtained card speed is corrected according to the movement of the human hand. For example, the moving speed of the card 12 is detected.

Further, not only optical means but also a rotary encoder 64 as shown in FIG. 4B is used to utilize frictional force when the card 12 passes through the slit 16, Alternatively, the rotational force of the roller 66 may be used to obtain a signal from the rotary encoder 64 to detect the speed.

Further, in this embodiment, the moving speed of the card 12 on which the bar code symbol 10 is recorded is detected. However, the card 12 is fixed and the line sensor 2 is used.
4 may be moved to detect this speed.

Further, in this embodiment, the FIFO memory 44
The write enable to the FIFO memory 44 is controlled by controlling the write enable to the FIFO memory 44, but the read enable from the line sensor 24 is controlled to control the write enable to the FIFO memory 44 without controlling the write enable of the FIFO memory 44.
Writing to may be stopped.

(Second Embodiment) FIG. 5 is a view showing the outer appearance of a bar code reader 68 according to the second embodiment of the present invention. In this embodiment, the card 12 on which the barcode symbol 10 is recorded is inserted into the insertion slot 70 of the card reader 68. Reference numeral 72 is various LEDs for displaying the status of the card reader 68.

FIG. 6 shows a bar code reader 68 of this embodiment.
2 is a block configuration diagram of the first embodiment, the same parts as those in FIG. 1 of the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. The bar code reader 68 of the present embodiment replaces the speed detecting unit 58 of the first embodiment with the card 1 inserted in the insertion opening 70.
It has a card drive unit 74 for carrying the card 2 and a speed controller 76 for controlling the carrying speed of the card 12.

As shown in FIG. 7A, the card drive section 74 is composed of a card receiver 78, a motor 80, etc., and the card 12 is inserted through the insertion port 70.
Card detecting section 2 provided with the tip of the card behind the card receiver 78
When the switch 82 at 6 is contacted, the pressing plate 84 of the card receiver 78 rises to fix the card 12 on the card receiver 78. After this, the card detection unit 2
As the reading is started in accordance with the reading start command from 6, the motor 80 is driven and the card receiver 78 is moved along the rail 86.

At this time, the speed controller 76 controls the motor 8 so that the moving speed of the card receiver 78 becomes a predetermined constant speed.
Servo to 0. Then, the write control 42 controls the write enable of the FIFO memory 44 at a predetermined timing in accordance with the movement speed of the card 12 which has become a predetermined constant speed in addition to the write operation enable / disable from the pointer management block 56. To do.

In this embodiment, after fixing the card 12 to the card receiver 78, the card receiver 78 is moved at a constant speed. However, after fixing the card 12 to the card receiver 78, the line sensor 24 is turned on. It may be moved at a constant speed.

(Third Embodiment) FIG. 7B shows a third embodiment of the present invention. In the embodiment, the card is passed through the slit 16 of the card reader as in the case of the above-described first embodiment, and the structure is almost the same as that of FIG. 1, but the structure of the speed detecting unit is different. . Further, in the card 12 'used in this embodiment, the marker 88 is recorded together with the barcode symbol 10 on the card 12'.

A sensor 90 is provided in the slit 16 of the card reader, and the card 12 'has the slit 1
When passing through the inside of the card 6, the marker 88 provided on the card 12 'is detected. The speed detecting unit detects the speed of the card 12 'from the temporal change of the markers 88 which are detected one after another, and thereafter performs the same processing as that of the first embodiment.

In this embodiment, the separate sensor 90 is used to detect the marker 88, but a part of the line sensor 24 for reading the bar code symbol 10 may be used.

[0040]

As described in detail above, according to the present invention,
It is possible to provide a bar code reader that shortens the decoding time of bar code information without storing useless information. That is, since the reading from the light receiving element or the writing to the storage element is controlled in synchronization with the moving speed, the moving speed of the barcode symbol recording medium is slow, or the moving speed of the barcode symbol recording medium is Even if you increase the scanning speed, you will not uselessly read, so
Decoding time does not become long. Further, by increasing the scanning speed, it is less likely that the line will change during scanning even if the moving speed of the barcode symbol recording medium is high.

[Brief description of drawings]

FIG. 1 is a block diagram of a bar code reader according to a first embodiment of the present invention.

2A is an external view of a system to which the barcode reader of the first embodiment is applied, and FIG. 2B is a diagram for explaining a specific operation of pointer management.

FIG. 3A is a diagram for explaining another example of data to be stored in a memory, and FIGS. 3B and 3C are diagrams each showing a configuration example of a speed detection unit.

FIG. 4A and FIG. 4B are diagrams showing another configuration example of a speed detection unit.

FIG. 5 is a diagram showing an appearance of a barcode reader according to a second embodiment of the present invention.

FIG. 6 is a block configuration diagram of a bar code reader according to a second embodiment.

FIG. 7A is a diagram showing a configuration of a card drive unit,
(B) is a diagram showing a structure of a speed detecting section in the third embodiment of the present invention.

FIG. 8 is a block diagram of a conventional barcode reading device.

[Explanation of Codes] 10 ... Bar Code Symbol, 12, 12 '... Card, 1
4, 68 ... Card reader, 16 ... Slit, 20 ... Host computer, 24 ... CCD line sensor, 26 ... Card detection unit, 28 ... Drive pulse generator, 30 ... Drive circuit, 32 ... Amplification circuit, 34 ... Sample and hold ( S / H) circuit, 36 ... Binarization circuit, 38 ... Bar / space width counter section, 40 ... Latch, 42 ... Write control control, 44 ... First-in first-out (FIFO) memory, 46 ... DSP, 48 ... Program ROM, 50 ... Working RAM, 52 ... Decode result output section, 54 ... Up / down counter, 56 ...
Pointer management block, 58 ... Speed detection unit, 60 ... LE
D, 62 ... Photodiode, 64 ... Rotary encoder, 66 ... Roller, 70 ... Insertion slot, 74 ... Card drive section, 76 ... Speed control section, 78 ... Card receiver, 80 ... Motor, 82 ... Switch, 84 ... Pushing Plate, 86 ... Rail, 8
8 ... Marker, 90 ... Sensor.

Claims (1)

[Claims] 1. An insertion port for inserting a recording medium on which a bar code symbol is recorded, a scanning unit for scanning the bar code symbol recorded on the recording medium inserted in the insertion port, and a read signal from the scanning unit. Based on the moving speed of the recording medium detected by the speed detecting means and the speed detecting means for detecting the moving speed of the recording medium inserted into the insertion opening, A bar code reader, comprising: a control unit that writes a read signal from the scanning unit into the storage unit so that a predetermined number of times of writing is performed per row.