JP4159571B2 - Bar code reader and start margin detection method thereof - Google Patents

Description

  The present invention relates to a barcode reader, and more particularly to a method for detecting a start margin of a barcode reader.

  A conventional bar code reader is configured as shown in FIG.

  Referring to FIG. 5, the barcode reader 500 receives a reflected light from a barcode to be read and outputs an electric signal corresponding to the intensity of the received light, and is output from the light receiving unit 501. An amplification unit 502 that amplifies the electric signal, a binarization unit 503 that converts the electric signal amplified by the amplification unit 502 into a binary signal corresponding to the barcode, and decodes the binarized signal And a decoding unit 511 that outputs a decoding result.

  When normal noise can be ignored, the electrical signal output from the light receiving unit 501 is an analog small signal as shown in FIG. 6A, and there is a margin MGN on the left and right of the barcode BD portion corresponding to the data portion. The margin MGN generally has a width of about 10 times the narrowest bar of the barcode BD.

  Of the left and right margins MGN, the margin MGN on the left side of the barcode portion is generally called a barcode start margin, and the margin MGN on the right side of the barcode portion is generally called a barcode end margin. I'm calling.

  The analog electrical signal output from the light receiving unit 501 is power amplified by the amplifying unit 502 to become an analog electrical signal as shown in FIG. When the analog electric signal amplified by the amplifying unit 502 is binarized by the binarizing unit 503, a binarized signal as shown in FIG. 6C is obtained. In the decoding unit 511, the binarized signal is obtained. The start margin SMGN and the barcode BD can be decoded and the barcode can be read.

Barcode reading that enables the setting of the generation timing of the margin detection signal to be adjusted according to the bar size and reading position of the barcode label to be read without having to calculate it one by one when performing such reading There exists an apparatus (refer patent document 1).
JP-A-5-35902

  However, the bar code symbol signal obtained from the bar code is not only a noiseless signal as shown in FIGS. 6A to 6C in each component of the bar code reader 500, but also the bar code. The start signal SMGN portion of the symbol signal may include an unnecessary signal SPRS as shown in FIGS.

  This is due to scratches, dirt, and STN in the start margin SMGN due to factors such as scratches, smudges, and insufficient surface treatment on the paper on which the bar code symbol label is printed, resulting in a bar code as shown in FIG. Therefore, the bar code reader 500 detects this scratch and dirt STN, and becomes an unnecessary signal SPRS.

  As described above, when the start margin SMGN has scratches and dirt STN, the electrical signal output from the light receiving unit 501 is an analog signal including an unnecessary signal SPRS in the start margin SMGN as shown in FIG. Small signal.

  The electric signal output from the light receiving unit 501 is amplified in power by the amplifying unit 502, and the unnecessary signal SPRS is also amplified as shown in FIG. 7B. When the electric signal including the unnecessary signal SPRS amplified by the amplifying unit 502 is binarized by the binarizing unit 503, a binarized signal as shown in FIG. 7C is obtained, and the binarizing signal is obtained by the decoding unit 511. Even if an attempt is made to detect the start margin SMGN of the digitized signal, the start margin SMGN cannot be detected because of the unnecessary signal SPRS in the start margin SMGN portion, and the unnecessary signal SPRS is recognized as a bar code and is different from the original bar pattern. The barcode of the first set of barcodes cannot be decoded, and it is determined as a decoding error, and the barcode cannot be read.

  As described above, the start margin SMGN has scratches, dirt STN, and the like, so that there is a problem that the start margin is insufficient and it is erroneously recognized as a bar, and it is determined as a decoding error and cannot be read.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a bar code reader that can be read even when the start margin of the bar code is dirty.

The bar code reader of the present invention optically reads a bar code symbol consisting of a start margin and a bar code formed by several bars following the start margin portion, and outputs data indicated by the bar code. A code reader,
The barcode symbol is optically read based on a drive signal composed of a start pulse for starting optical reading and a stop pulse for ending the optical reading, and is converted into an electrical signal and output. The light receiving unit;
When the start margin is detected and the barcode is decoded based on the output contents of the electrical signal of the light receiving unit that is periodically input, the start margin cannot be detected or the barcode is decoded. A decoding unit that outputs an undecipherable signal indicating that if not,
Using the start pulse as a trigger, a part of the electrical signal where the start margin is detected and the barcode is decoded in the decoding unit is partially canceled, and the cancel part has a predetermined pulse width. A cancel signal generating unit that outputs a cancel signal formed by a signal so that an area to be canceled becomes longer each time the undecipherable signal is input,
It is characterized by providing.

  In the market, there is a demand for a barcode reader that can read even a barcode symbol label with a dirty start margin.

  When reading a barcode symbol with a dirty start margin, an unnecessary signal generated due to the contamination may cause an obstacle to the detection of the start margin, and the barcode reader may not be able to detect the start margin. I cannot decode the barcode.

  The present invention incorporates a function for canceling and removing an unnecessary signal due to contamination of a start margin portion of a bar code symbol into the bar code reader so that the electric signal read by the light receiving unit when the bar code symbol cannot be decoded. In addition, a cancel signal for canceling the unnecessary signal is superposed, the unnecessary signal is forcibly canceled, the barcode portion of the electric signal is decoded, and the start margin is detected.

  The cancel part of this cancel signal can be deciphered because the start margin width differs depending on the type of bar code symbol and the bar width, and the position of the start margin where dirt adheres to the start margin cannot be predicted in advance. If there is not, it is better to gradually expand this cancellation part.

  This cancel signal removes unnecessary signals in the portion corresponding to the start margin of the barcode symbol, and when the width of the start margin portion can be secured, the reading can be performed in the same manner as when the start margin is not contaminated. After detecting this start margin, the barcode can be decoded.

  According to the present invention, it is possible to obtain a barcode reader that can be read even when the start margin of the barcode is dirty.

  Embodiments for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram illustrating a configuration example of a barcode reader according to the present embodiment.

  Referring to FIG. 1, a bar code reader 100 irradiates a bar code symbol 200 to be read with light projecting unit 110, and the bar code symbol 200 reflects the irradiated light and scans the reflected light. The light receiving unit 101 that outputs an electrical signal corresponding to the intensity of the received light, the amplification unit 102 that amplifies the electrical signal output from the light receiving unit 101, and the electrical signal amplified by the amplification unit 102 Is converted into a binary digital signal corresponding to the barcode symbol 200, a light receiving drive pulse signal is superimposed on the binary digital signal, and output as a superimposed binary signal, 2 The portion corresponding to the start margin of the superimposed binary signal formed from the binary digital signal is assigned to the barcode symbol 200 by a cancel signal, which will be described later. A start margin canceling unit 106 for canceling the margin and a control unit 104 for controlling each component of the bar code reader 100. The bar code symbol 200 is optically read, and a signal indicated by the bar code Is output, and the bar code displayed on the bar code symbol 200 is decoded.

  The barcode symbol 200 includes, for example, a start margin portion formed of a white blank portion, a barcode portion formed of several sets of bars following the start margin portion, and a white portion from a portion where the barcode portion ends. It consists of an end margin portion formed by a blank portion.

  In this example, the barcode part formed by several pairs of bars consists of a white part and a black part each having a certain width, and this white part and the black part are combined to correspond to a binarized binary number. It is a code to do.

  Generally, the provided start margin portion and end margin portion are each formed by a white blank portion having a width of about 10 times the narrowest bar width of the barcode portion of the barcode symbol 200.

  Of course, the barcode symbol 200 is not limited to the one formed by the black and white portions, and can be distinguished from light and shade. Is not limited.

  The analog electrical signal output from the light receiving unit 101 is obtained by converting the optically read content of the barcode symbol 200 into an electrical signal, and corresponds to the start margin portion of the barcode symbol 200. The start margin signal, the barcode signal corresponding to the barcode portion of the barcode symbol 200, and the end margin signal corresponding to the end margin portion of the barcode symbol 200 are included.

  In the electrical signal output from the amplifying unit 102 or the superimposed binarized signal output from the binarizing unit 103, similarly to the analog electrical signal output from each light receiving unit 101, the start of the barcode symbol 200 is started. It consists of a start margin signal portion corresponding to the margin portion, a barcode signal corresponding to the barcode portion of the barcode symbol 200, and an end margin signal portion corresponding to the end margin portion of the barcode symbol 200. Yes. Hereinafter, even in a signal subjected to amplification processing in the amplification unit 102 and binarization processing in the binarization unit 103, a signal corresponding to the start margin portion is referred to as a start margin signal, and a signal corresponding to the barcode portion is referred to. This is called a bar code signal.

  The amplifying unit 102 amplifies power of the output contents of the electrical signal from the light receiving unit 101 that is periodically input, that is, the analog electrical small signal including the start margin signal, the barcode signal, and the end margin signal, Output.

  The control unit 104 includes a light projection drive signal generation unit 114 that generates a light projection drive pulse signal as a light projection drive signal that drives the light projection unit 110, and a light reception drive signal that drives and scans the light reception unit 101. A light receiving drive signal generator 113 for generating a light receiving drive pulse signal and a start margin signal of a binary digital signal for canceling the start margin given to the barcode symbol 200 (this is output from the light receiving unit 101) A cancel signal generation unit 112 that generates a cancel signal in which a canceling portion is formed with a predetermined pulse width and a portion corresponding to the start margin of the superimposed binarized signal are detected. After that, the decoding unit 111 that decodes the superimposed binary signal canceled by the cancellation signal Configured to include a.

  The decoding unit 111 detects the start margin of the bar code symbol 200 and the bar code based on the superimposed binarized signal obtained by the binarizing unit 103 based on the output content of the electrical signal of the light receiving unit 101 that is periodically input. When the code is decoded and the start margin cannot be detected or the bar code cannot be decoded, it has a function of outputting a decoding impossible signal indicating that.

  The cancel signal generation unit 112 receives the decoding impossible signal from the decoding unit 111, and the decoding unit 111 of the electric signal (here, corresponding to the superimposed binary signal after the electric signal is processed). A cancel signal for partially canceling a signal composed of a start margin signal corresponding to a region where the start margin is detected and a barcode signal corresponding to a region where the decoding of the barcode is performed in the decoding unit 111 Has a function of outputting so that the area for canceling becomes longer.

  The cancel signal generator 112 of the present embodiment generates a cancel signal having a predetermined pulse width in order to partially cancel the start margin signal corresponding to the start margin SMGN area of the barcode symbol 200. By gradually widening the pulse width for each scan (that is, every time an undecipherable signal is input), the area for canceling the start margin SMGN becomes longer.

  The light receiving unit 101 is connected to the amplifying unit 102, the amplifying unit 102 is connected to the binarizing unit 103, the binarizing unit 103 is connected to the start margin canceling unit 106, and the start margin canceling unit 106 is connected. Are connected to the decoding unit 111.

  The decoding unit 111 is connected to the cancel signal generating unit 112, the cancel signal generating unit 112 is connected to the light receiving drive signal generating unit 113, and the light receiving drive signal generating unit 113 is connected to the light receiving unit 101. The light drive signal generation unit 114 is connected to the light projecting unit 110, the light reception drive signal generation unit 113 is connected to the binarization unit 103, and the cancel signal generation unit 112 is connected to the start margin cancellation unit 106. Yes.

  Next, the operation of the barcode reader 100 will be described in detail with reference to FIGS.

  In order to read the barcode symbol 200, the barcode reader 100 is arranged with the light projecting unit 110 and the light receiving unit 101 of the barcode reader 100 facing the barcode symbol 200.

  From the barcode reader 100, a light projection drive signal which is a light projection drive signal composed of a start pulse and a stop pulse is output from the light projection drive signal generator 114.

  The time from the start pulse to the stop pulse corresponds to a scan time in which the barcode reader 100 scans once to optically read the barcode symbol 200, and the entire code of the barcode symbol 200 to be read corresponding to this time. Specifies the width.

  The projection drive pulse signal output from the projection drive signal generation unit 114 is input to the projection unit 110.

  When the start pulse is input by the light projection drive pulse signal input to the light projecting unit 110, the light projecting unit 110 starts irradiating light to the barcode symbol 200, and when the stop pulse is input. In addition, the light projecting unit 110 ends the light irradiation on the barcode symbol 200. However, the light irradiation does not have to end in synchronization with the stop pulse. During the light irradiation by the light projecting unit 110, the barcode symbol 200 is scanned once.

  The barcode symbol 200 irradiated with the light from the light projecting unit 110 reflects the irradiated light, and the light reflected by the barcode symbol 200 is directed to the light receiving unit 101 of the barcode reader 100.

  The light receiving unit 101 periodically receives the light receiving drive pulse signal output from the light receiving drive signal generating unit 113. FIG. 2A shows the light reception drive pulse signal output from the light reception drive signal generator 113. As shown in the figure, the light receiving drive pulse signal is composed of a start pulse 703 and a stop pulse 708 in the same manner as the light projection drive pulse signal already described.

  The time from the start pulse 703 to the stop pulse 708 corresponds to the scan time T1 when the barcode reader 100 scans the barcode symbol 200 once, and the width of the entire barcode symbol 200 to be read corresponding to this time is defined. is doing.

  In other words, the bar code symbol signal obtained by the bar code reader 100 is always included in the light receiving drive pulse signal, thereby enabling periodic bar code reading.

  The light receiving unit 101 performs scanning for optically reading the barcode symbol 200 based on the light receiving drive pulse signal input to the light receiving unit 101. The scanning of the light receiving unit 101 starts from the time of the start pulse 703 with the start pulse 703 of the light receiving drive pulse signal as a trigger, and one scan (scan) ends at the time of the stop pulse 708 of the light receiving drive pulse signal.

  By the scanning of the light receiving unit 101, the reflected light from the barcode symbol 200 is periodically input to the light receiving unit 101.

  The light receiving unit 101 converts the optically read content of the barcode symbol by the input reflected light into an analog electric signal corresponding to the intensity of the reflected light and outputs the analog electric signal.

  The analog electrical signal composed of the start margin signal and the barcode signal is input to the amplifying unit 102, power amplified in the amplifying unit 102, and output from the amplifying unit 102. The analog electrical signal output from the amplification unit 102 is input to the binarization unit 103.

  The binarization unit 103 converts the analog electric signal input from the amplification unit 102 into a binarized signal of logic “0” (logic “low”) and “1” (logic “high”). The digital signal is shaped to be converted into a binary digital signal that is an electrical signal corresponding to the barcode symbol 200. This binarized binary digital signal is shown in FIG.

  In the binarized binary digital signal shown in FIG. 2B, for example, the black portion of the barcode corresponds to logic “0” (logic “low”), and the white portion of the barcode represents logic “0”. 1 ”(logic“ high ”).

  In the binarization unit 103, the light reception drive pulse signal (see FIG. 2A) input from the light reception drive signal generation unit 113 to the binarization unit 103 is further added to the binarized binary digital signal. Superimpose. As a specific circuit for superimposing the binary digital signal and the light receiving drive pulse signal, for example, an AND circuit (AND circuit) may be used.

  A binarized signal in which the light reception driving pulse signal is superimposed in this way is output from the binarizing unit 103. FIG. 2C shows a binarized signal on which a light reception driving pulse signal (start pulse 703 and stop pulse 708) is superimposed, and this signal is hereinafter referred to as a superimposed binarized signal.

  In this superimposed binarized signal, as shown in FIG. 2 (d), SMGN is between the rear edge of the start pulse 703 and the front edge of the first pulse of the first set of the barcode of the binarized signal. It almost corresponds to the start margin of the barcode symbol 200, and this portion corresponds to the start margin signal of the electric signal.

  The SMGN from the rear edge of the start pulse 703 to the front edge of the first pulse of the binarized signal is hereinafter referred to as the start margin SMGN of the bar code symbol 200 for the sake of simplicity.

  If the binarized signal has a sufficient margin width in the start margin SMGN as shown in the figure, the start margin SMGN can be detected, so that the barcode can be decoded without any problem, but is unnecessary for the start margin SMGN. If there is a signal, a decoding error occurs.

  FIG. 2E shows a superimposed binarized signal when an unnecessary signal is superimposed on the start margin SMGN.

  The superimposed binarization signal shown in the figure is when the paper on which the barcode symbol label is printed is scratched or dirty, or when there is a defect in the surface treatment of the label. For this reason, an unnecessary signal is included in the light detected by the light receiving unit 101 that has received the light reflected from the barcode symbol 200, and this unnecessary signal is also converted into an electrical signal, which is unnecessary for the start margin SMGN. A state in which the signal SPRS is included is shown.

  In the prior art, if the start margin portion of the barcode symbol is contaminated as described above, it is erroneously recognized as a bar or the start margin width is insufficient, and the barcode reader 500 (see FIG. 5) causes a decoding error. The barcode symbol could not be decoded.

  On the other hand, in the barcode reader 100 of the present embodiment, the following processing is continuously performed.

  The light reception drive signal generation unit 113 also supplies the output light reception drive pulse signal to the cancel signal generation unit 112. In the cancel signal generation unit 112 to which the light receiving drive pulse signal is input, a cancel region having a pulse having a predetermined pulse width when necessary using the rear edge of the start pulse 703 as a trigger based on the light receiving drive pulse signal. A cancel signal is generated. This cancel signal is shown in FIG.

  When a pulse having a predetermined pulse width is required for this cancel signal, the start margin can not be detected by the decoding unit 111 on the superimposed binary signal of the bar code symbol 200 obtained by first scanning with the light receiving unit 101 Or it is the case where it cannot decode, trying to decode, and refers to the case of performing the second and subsequent scans.

  As described above, when the decoding unit 111 cannot decode the barcode symbol 200 in the first scanning of the light projecting unit 110 and the light receiving unit 101, the decoding unit 111 cannot detect the start margin for decoding. Alternatively, an undecipherable signal indicating that the bar code could not be deciphered is output, and the cancel signal generator 112 is notified.

  As described above in the background art, the reason why the decoding unit 111 cannot decode the barcode symbol 200 is that the start margin of the barcode symbol 200 is dirty, and therefore the start margin cannot be detected. The 200 barcode may not be decipherable.

  In such a case, the decoding unit 111 notifies the cancel signal generation unit 112 that the start margin could not be detected or the barcode symbol 200 could not be decoded.

  The cancel signal generation unit 112 that has received the notification from the decoding unit 111 by the non-decipherable signal when the light projecting unit 110 and the light receiving unit 101 of the barcode reader 100 performs the second scan performs the light reception drive signal generation unit 113. 2 receives the pulse signal for light reception drive from, and outputs the cancel signal shown in FIG. 2 (f) and supplies it to the start margin cancel unit 106.

  The superimposed binarized signal output from the binarizing unit 103 is input to the start margin canceling unit 106. The start margin canceling unit 106 generates an unnecessary signal in the start margin SMGN portion of the superimposed binarized signal as a cancel signal. Canceling is performed by forcibly setting a high level (H) with a cancel signal supplied from the unit 112. FIG. 2 (g) shows a superimposed binary signal in which the start margin SMGN is canceled.

  In this way, the superimposed binary signal from which the unnecessary signal SPRS in the start margin SMGN portion is removed by the cancel signal is the same as the signal read from the barcode symbol 200 where the portion corresponding to the start margin of the barcode symbol 200 is not contaminated. The superimposed binarized signal is output from the start margin canceling unit 106 and input to the decoder unit 111 of the control unit 104.

  Since the unnecessary signal SPRS of the start margin SMGN is removed from the superimposed binary signal input to the decoder unit 111 by the cancel signal, the start margin SMGN of the barcode symbol 200 is secured, and the decoding unit 111 The start margin SMGN is detected from the superposed binary signal without the unnecessary signal SPRS, and the barcode is decoded in the same manner as when there is no unnecessary signal.

  The decoding unit 111 decodes the barcode and outputs a signal indicated by the barcode. For example, the decoding unit 111 displays it on a display unit (not shown) of the barcode reader 100 or displays and prints information corresponding to the decoded barcode. Or

  Here, the generation state of the cancel signal when canceling the start margin SMGN and forming the superimposed binary signal shown in FIG. 2G will be described in more detail with reference to FIG.

  FIG. 3A shows a light reception drive pulse signal output from the light reception drive signal generation unit 113, and FIG. 3B shows superposition binarization when an unnecessary signal is superimposed on the start margin SMGN. Signals are shown.

  The light reception drive pulse signal in FIG. 3A is the light reception drive pulse signal shown in FIG. 2A, and the superimposed binarization signal in FIG. 3B is shown in FIG. This is a superimposed binary signal when the unnecessary signal SPRS is superimposed on the start margin SMGN.

  FIG. 3C illustrates a case where the light projecting unit 110 and the light receiving unit 101 perform the first scan, and the superimposed binarized signal illustrated in FIG. The cancel signal supplied from the cancel signal generator 112 to the start margin cancel unit 106 at this time is shown.

  This cancel signal is a signal generated from the cancel signal generation unit 112 during the first scan of the light projecting unit 110 and the light receiving unit 101. Unlike the cancel signal shown in FIG. 2 (f), a pulse having a predetermined pulse width is generated. This is a cancel signal that does not exist.

  Since this cancel signal does not have a predetermined pulse width, the start margin cancel unit 106 cannot remove the unnecessary signal SPRS in the start margin SMGN of the superimposed binarized signal.

  In this case, the superimposed binarized signal output from the binarizing unit 103 is input to the start margin canceling unit 106, and the cancel signal is input from the cancel signal generating unit 112 to the start margin canceling unit 106. Since the cancel signal does not have a predetermined pulse width, the superimposed binary signal passes through the start margin cancel unit 106 as if it is through and is input to the decode unit 111.

  That is, the unnecessary signal SPRS in the start margin SMGN portion of the superimposed binarized signal remains as it is when the start margin canceling unit 106 is output. Even if this superimposed binarized signal is input to the decoding unit 111, the start margin Due to the unnecessary signal SPRS in the SMGN portion, the decoding unit 111 cannot detect the start margin SMGN and cannot decode the barcode of the barcode symbol 200.

  The fact that the start margin could not be detected and the barcode could not be decoded is notified from the decoding unit 111 to the cancel signal generating unit 112 by a decoding impossible signal.

  Upon receiving the notification from the decoding unit 111, the cancel signal generation unit 112 generates a cancel signal having a predetermined pulse width when the light projecting unit 110 and the light receiving unit 101 are scanned for the second time.

  This cancel signal is shown in FIG.

  FIG. 3D shows a case where the light projecting unit 110 and the light receiving unit 101 perform the second scan, and the superimposed binary signal shown in FIG. The cancel signal supplied from the cancel signal generator 112 at this time is shown, and this cancel signal is a signal that has a predetermined pulse width T2 to be canceled.

  Although this cancel signal has a predetermined pulse width T2, the start margin cancel unit 106 cannot remove the unnecessary signal in the start margin SMGN of the superimposed binarized signal.

  This is because a part of the start margin SMGN of the superimposed binarized signal shown in FIG. 3B is canceled, but a part of the unnecessary signal SPRS is not canceled and unnecessary because of the pulse width T2. The signal SPRS cannot be removed.

  In this case, the superimposed binarized signal output from the binarizing unit 103 is input to the start margin canceling unit 106, and the cancel signal is input from the cancel signal generating unit 112 to the start margin canceling unit 106. Since the pulse width T2 of the cancel signal is not a pulse width capable of removing the unnecessary signal SPRS, the superimposed binary signal from which the unnecessary signal SPRS is not removed is output from the start margin canceling unit 106 and input to the decoding unit 111.

  That is, the unnecessary signal SPRS in the start margin SMGN portion of the superimposed binarized signal remains as it is when the start margin canceling unit 106 is output. Even if this superimposed binarized signal is input to the decoding unit 111, the start margin Due to the unnecessary signal SPRS in the SMGN part, the decoding unit 111 cannot detect the start margin SMGN and cannot decode the bar code.

  When the bar code cannot be decoded, the decoding unit 111 notifies the cancel signal generation unit 112 that the bar code could not be decoded or the start margin SMGN could not be detected.

  Upon receiving the notification from the decoding unit 111, the cancel signal generating unit 112, when the third scanning of the light projecting unit 110 and the light receiving unit 101 is performed, is larger than a predetermined pulse width T2 at the second scanning. A cancel signal with an expanded pulse width is generated during the third scan.

  FIG. 3 (e) shows a cancel signal with an expanded pulse width.

  In FIG. 3E, the light projecting unit 110 and the light receiving unit 101 perform the third scan, and the superimposed binarized signal shown in FIG. The cancel signal supplied from the cancel signal generator 112 at this time is shown, and the cancel signal has a predetermined pulse width T3 whose canceling portion is wider than the pulse width T2 shown in FIG. There is only a signal.

  This cancel signal has a predetermined pulse width T3, but the start margin cancel unit 106 cannot remove the unnecessary signal SPRS in the start margin SMGN of the superimposed binarized signal.

  This is because a part of the start margin SMGN of the superimposed binarized signal shown in FIG. 3B is canceled, but because of the pulse width T3, a part with the unnecessary signal SPRS is not canceled and is unnecessary. The signal SPRS cannot be removed.

  In this case, the superimposed binarized signal output from the binarizing unit 103 is input to the start margin canceling unit 106, and the cancel signal is input from the cancel signal generating unit 112 to the start margin canceling unit 106. Since the pulse width T3 of the cancel signal is not a pulse width that can remove the unnecessary signal SPRS, the superimposed binary signal from which the unnecessary signal SPRS is not removed is output from the start margin canceling unit 106 and input to the decoding unit 111.

  That is, the unnecessary signal SPRS in the start margin SMGN portion of the superimposed binarized signal remains as it is when the start margin canceling unit 106 is output. Even if this superimposed binarized signal is input to the decoding unit 111, the start margin Due to the unnecessary signal SPRS in the SMGN part, the decoding unit 111 cannot detect the start margin SMGN and cannot decode the bar code.

  When the bar code cannot be decoded, the decoding unit 111 notifies the cancel signal generation unit 112 that the bar code could not be decoded or the start margin SMGN could not be detected.

  Upon receiving the notification from the decoding unit 111, the cancel signal generating unit 112, when the fourth scanning of the light projecting unit 110 and the light receiving unit 101 is performed, is larger than a predetermined pulse width T3 at the time of the third scanning. A cancel signal with an expanded pulse width is generated.

  FIG. 3 (f) shows a cancel signal with an expanded pulse width.

  FIG. 3 (f) shows a case where the light projecting unit 110 and the light receiving unit 101 perform the fourth scan, and the superimposed binarized signal shown in FIG. 3 (b) by the reflected light from the barcode symbol 200 as a result of this scan. The cancel signal supplied from the cancel signal generator 112 at this time is shown, and the cancel signal has a predetermined pulse width T4 whose canceling portion is wider than the pulse width T3 shown in FIG. There is only a signal.

  This cancel signal has a predetermined pulse width T4, and the start margin cancel unit 106 can remove the unnecessary signal SPRS in the start margin SMGN of the superimposed binarized signal.

  This is because the start margin SMGN of the superimposed binarized signal shown in FIG. 3B is canceled by the cancel portion of the cancel signal, that is, a portion of the unnecessary signal SPRS is canceled because of the pulse width T4. The unnecessary signal SPRS can be removed.

  In this case, the superimposed binarized signal output from the binarizing unit 103 is input to the start margin canceling unit 106, and the cancel signal is input from the cancel signal generating unit 112 to the start margin canceling unit 106. Since the pulse width T4 of the cancel signal in the start margin canceling unit 106 is a pulse width that can remove the unnecessary signal SPRS, the superimposed binary signal from which the unnecessary signal SPRS is removed is output from the start margin canceling unit 106, and the decoding unit 111 Is input.

  That is, since the unnecessary signal SPRS in the start margin SMGN portion of the superimposed binarized signal is in the cancel portion (region), it is removed when the start margin cancel unit 106 is output. When input to the decoding unit 111, the decoding unit 111 detects the start margin signal of the start margin SMGN portion, and the detection of the start margin SMGN results in the decoding unit 111 being formed of several pairs of bars. The bar code signal corresponding to the bar code is sequentially processed from the left to decode the bar code signal.

  As described above, the predetermined pulse width of the cancel signal gradually increases with each scan, but this pulse width is expanded in units of the width of the narrowest bar of the barcode. In order to increase the predetermined pulse width of the cancel signal, the unnecessary signal SPRS included in the start margin SMGN is canceled, and the unnecessary signal SPRS of the start margin SMGN is removed by the start margin canceling unit 106 by this cancel signal. The predetermined pulse width is repeatedly expanded every scan until

  When the unnecessary signal SPRS is removed by this cancel signal and the width of the start margin SMGN can be secured, the decoder 111 detects the start margin SMGN of the superimposed binarized signal, and then decodes the bar code signal to detect the bar code signal. The code can be decoded.

  The removal of the unnecessary signal SPRS by the cancel signal can be performed by reading and decoding the barcode while avoiding the unnecessary signal SPRS portion by shifting the timing of reading the electric signal by this processing.

  The increment amount of the pulse width of the cancel signal can be arbitrarily set by the start margin cancel unit 106 or software for controlling the start margin cancel unit 106, and can correspond to the bar code symbol 200 having any bar width by setting the increment. It becomes possible.

  Further, the increment amount of the pulse width of the cancel signal can be arbitrarily set by the start margin canceling unit 106 or software for controlling the start margin canceling unit 106, and it corresponds to the barcode symbol 200 having any start margin width by setting the increased amount. It becomes possible.

  In this way, even in the case of a superimposed binary signal having an unnecessary signal SPRS in the start margin SMGN, an unnecessary signal of the barcode start margin SMGN is used instead of detecting the start margin by a conventional barcode reader. By forcibly canceling the included portion and forming the start margin SMGN in a pseudo manner, the same effect as that obtained by detecting the start margin SMGN can be obtained. Even if there are scratches or dirt in the margin portion, it can be decoded and an excellent effect of improving the barcode reading rate can be obtained.

  Further, the barcode reader 100 according to the present embodiment can read not only the barcode symbol 200 in which an unnecessary signal is superimposed on the start margin SMGN but also the following cases.

  When the barcode reader 100 reads the barcode symbol 200 and there is no unnecessary signal SPRS in the start margin SMGN, a decoding error occurs when decoding is performed even though the start margin SMGN can be detected by the decoding unit 111. There is.

  The cause of this decoding error is that the first code of the barcode of the barcode symbol 200 has a printing blur, a code width, etc., as in the superimposed binarized signal shown in FIG. This is because the first barcode 401 cannot be read due to the widening of the code width.

  Even in such a case, if the barcode cannot be decoded by the decoding unit 111 in the first scanning of the light projecting unit 110 and the light receiving unit 101 as described above, the decoding unit 111 cancels that the decoding cannot be performed. The signal generation unit 112 is notified by a decoding impossible signal.

  Upon receiving the notification from the decoding unit 111, the cancel signal generation unit 112 receives light from the light reception drive signal generation unit 113 when the light projecting unit 110 and the light receiving unit 101 of the barcode reader 100 perform the second and subsequent scans. In response to the drive pulse signal, a cancel signal having a predetermined pulse width gradually increased as shown in FIGS. 3D to 3F is output and supplied to the start margin cancel unit 106.

  When the first code of this bar code has printing blur, code width, etc., as a result of gradually increasing the predetermined pulse width of this cancel signal, the bar code as shown in FIG. When the edge of the first pulse of the first set of the first edge is applied to the rear edge of the cancel signal and the blurring portion of the edge of the first pulse of the first set is removed by the cancel signal, The pulse 402 can be detected.

  For this reason, the barcode can be decoded, and the barcode is decoded after the start margin SMGN is detected.

  Thus, even when the first one of the bar code symbol 200 cannot be binarized, the predetermined pulse width of the cancel signal is gradually expanded by the same operation, and the first code of the bar code is blurred. When removed, the first code pulse can be detected and the barcode can be decoded.

  In the barcode reader 100 of this embodiment, the start margin SMGN is formed in the superimposed binary signal by providing the start margin canceling unit 106 with the configuration shown in FIG. Decoding is made possible, but is not limited to this.

  Instead of providing the start margin canceling unit 106 as hardware, software having the function of the start margin canceling unit 106 is incorporated in the control unit 104, for example, and the same processing as the start margin canceling unit 106 is performed by this software. The start margin SMGN may be forcibly formed by the above and decoding may be performed.

  Further, although the embodiment has been described in which the cancel signal cancels the start margin SMGN portion of the superimposed binarized signal, the present invention is not limited to this, and the binarization unit 103 cancels the binarized signal. In addition, for example, it is possible to cancel the portion corresponding to the start margin of the analog electric signal before binarization, and the unnecessary signal portion can be avoided by shifting the timing of reading the electric signal by this processing. It is possible to read and decode barcodes.

  Further, the embodiment has been described in which the cancel signal is formed by using the start pulse as a trigger to form a region to be canceled with a predetermined pulse width from the rear edge of the start pulse. However, the present invention is not limited to this. A part of the unnecessary signal is detected from the start margin signal of the electrical signal output from 101, and an unnecessary signal superimposed on the start margin signal by a cancel signal in which a canceling area is formed around the part where the unnecessary signal is detected. May be canceled.

  In addition, if it cannot be deciphered in the description, a cancel signal having an expanded cancel portion (predetermined pulse width) is input to the start margin cancel unit 106 when the next scan is performed. Instead of performing the subsequent scanning, for example, a superimposed binary signal is stored in the start margin canceling unit 106, and a cancellation signal having a longer cancellation area is superimposed on the stored superimposed binary signal. A similar process may be performed.

  Although the end margin detection is not described in the present embodiment, it is natural that end margin detection may be performed as in the conventional case, and the start of the present embodiment is also performed when necessary in the end margin detection. Processing similar to margin cancellation and detection may be performed by hardware or software.

It is a block diagram which shows the structural example of the barcode reader of this embodiment. FIGS. 2A to 2G are diagrams showing signals output from each component of the barcode reader. FIGS. 3A to 3F are diagrams illustrating a state in which the pulse width of the cancel signal output from the cancel signal generation unit is widened based on the light reception drive pulse signal from the light reception drive signal generation unit. FIG. 4A is a diagram showing a superimposed binarized signal that cannot be deciphered due to printing blur, code width expansion, etc., in the first set of barcode codes. FIG. 4B is a diagram showing a superimposed binarized signal in which printing blur, code width expansion, and the like are removed by the cancel signal, and become decipherable. It is a block diagram which shows the structural example of the barcode reader of a prior art. FIGS. 6A to 6C are explanatory diagrams showing electric signals in which unnecessary signals are not superimposed on the start margin portion. FIGS. 7A to 7C are explanatory diagrams showing electrical signals in which unnecessary signals are superimposed on the start margin portion. It is a general-view figure which shows the barcode symbol which has a crack and dirt in a start margin part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Barcode reader 101 Light receiving part 102 Amplifying part 103 Binarization part 104 Control part 106 Start margin cancellation part 110 Light projection part 111 Decoding part 112 Cancel signal generation part 113 Light reception drive signal generation part 114 Light projection drive signal generation part 200 Bar Code symbol 401 First bar code 402 First pulse 500 Bar code reader 501 Light receiving unit 502 Amplifying unit 503 Binarizing unit 511 Decoding unit 703 Start pulse 708 Stop pulse BD Bar code MGN margin SMGN Start margin SPRS Unnecessary signal STN Dirt

Claims (1)

A bar code reader that optically reads a bar code symbol consisting of a start margin and a bar code formed by several sets of bars following the start margin part, and outputs data indicated by the bar code,
The barcode symbol is optically read based on a drive signal composed of a start pulse for starting optical reading and a stop pulse for ending the optical reading, and is converted into an electrical signal and output. The light receiving unit;
When the start margin is detected and the barcode is decoded based on the output contents of the electrical signal of the light receiving unit that is periodically input, the start margin cannot be detected or the barcode is decoded. A decoding unit that outputs an undecipherable signal indicating that if not,
Using the start pulse as a trigger, a part of the electrical signal where the start margin is detected and the barcode is decoded in the decoding unit is partially canceled, and the cancel part has a predetermined pulse width. A cancel signal generating unit that outputs a cancel signal formed by a signal so that an area to be canceled becomes longer each time the undecipherable signal is input,
A bar code reader comprising:

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