JPS6352277A - barcode reader - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a barcode reading device.

BACKGROUND OF THE INVENTION In recent years, barcodes have been widely used in PO8 sales and distribution, and barcode readers for reading and recognizing such barcodes have been actively developed.

FIG. 2 shows an example of such a barcode reader. First, label the opening 1a of the main body cover 1 with the label 2.
A light source 3 (LED
array configuration) to illuminate the barcode 4 on the label 2. Then, the reflected light from the barcode 4 is transferred to a mirror 5,
An image is formed on a line sensor 8 such as a CCD through an imaging lens 6 and a slit 7. This line sensor 8
The photoelectrically converted and read signal is input to the signal processing circuit 9, amplified and sampled and held, and then converted by the binarization circuit 10 into a digital signal of rlJ or "0" indicating either black or white. This digital signal is converted by a run-length encoding circuit 11 into a run-length code indicating the width of the white and black bars. This run-length code is analyzed and decoded by a microcomputer 12, and the decoded result is output to a data processing device 13 such as a register.

14 is a light source drive circuit, and 15 is a line sensor drive circuit.

In such a barcode reader, it is necessary to prevent the decoding results obtained from the barcode 4 of the same label 2 from being transferred to the data processing device 13 in duplicate during one reading operation. Therefore, after the decoding result is transferred once to the data processing device 13, the decoding process is prohibited or the transfer of the decoding result is prohibited until the main body cover 1 is separated from the label 2, thereby preventing double reading. A mechanism is provided.

Problems to be Solved by the Invention In order to carry out processing using such a double reading prevention mechanism, it is necessary to detect the positional relationship (approaching/separating) of the main body cover of the barcode reader with respect to the label (barcode). Conventionally, as shown in FIG. 2, a distance sensor 16 is provided in the opening la to detect the distance from the label 2 using reflected light. Since such a distance sensor 16 is required, it is disadvantageous in terms of cost and weight reduction.

Also, recently, labels 2 with two-stage barcodes 4 as shown in FIG. 3 have been widely used in clothing-related sales departments. When attempting to read such a two-stage (or multi-stage) barcode, the double reading prevention mechanism described above decodes the first stage barcode and transfers the decoding result to the data processing device. After that, the next barcode cannot be read and decoded unless the barcode reader is once separated from the label. In other words, continuous reading of two-stage or multi-stage barcodes is not possible.

Means for Solving Problems Comparison means for comparing the read data with the barcode recognition setting number, a first storage means for storing the current read data,
a second storage means for storing previously read data; and a comparison means for comparing the contents of the first storage means and the second storage means under the condition that the comparison result by the comparison means is equal to or greater than the set number of barcode recognitions. , a number detection means for detecting the number of consecutive departures from a barcode that branches to a departure check routine when the comparison result by the comparison means is equal to or less than the set number of barcode recognition; and a separation determination means for detecting the duration of the separation check routine by comparing the above and determining whether or not there is a separation state.

Effect The further away from the barcode you are when reading the barcode, the more
The resolution of the entire optical system of the reading device is reduced. This makes it difficult to read and reproduce the thin bars in the barcode.

As a result, the number of read data (number of run length data) decreases as the distance from the barcode increases. Therefore, by comparing this read data with a predetermined number of barcode recognition settings using a comparing means, it is detected that if the number is smaller than the set number, it is detected that the barcode is moving away, and if it is larger than the set number, it is detected that the barcode is approaching.

Then, each time read data is obtained in the state of approaching the barcode, the previous read data is stored in the second storage means, the current read data is stored in the first storage means,
Each time, the contents of both are compared using a comparison means. Only when the results of this comparison are different, it is assumed that the barcode to be read has changed and is made valid. In other words, even in the case of a two-stage barcode, etc., continuous reading is performed. On the other hand, even if it is determined that the user has defected from the barcode, there may be a false defection state due to a decrease in dynamic resolution, etc., but the defective check routine continues for a predetermined number of defections through processing by the number of times detection means and defection determination means. Unless the situation is excluded, it is considered a pseudo defection and is distinguished from an actual defection state.

Example An embodiment of the present invention will be described based on FIG.

The basic configuration is the same as that shown in FIG. 2, but there are major differences in the absence of the distance sensor 16 and the processing within the microcomputer 12. After the bar width information of the white and black bars obtained by the run length encoding circuit 11 is taken into the microcomputer 12, decoding processing as shown in FIG. 1 is performed.

First, initialization is performed to clear the value of a counter N indicating the number of departures from the barcode during decoding processing and a flag that is set when the decoding result is transferred to the data processing device 13 for the first time within one reading operation. Next, import run length data. Then, the comparison means 17 examines the number of captured run-length data and compares the captured data number with a threshold value THI to check whether the reading device is approaching or moving away from the barcode (label). Here, the threshold (aTHl) is determined by the configuration and operating method of the optical system, and is the number of barcode recognition settings.

Here, the principle by which approaching and moving away from a barcode can be detected will be explained. Generally, the further away from the barcode the resolution of the optical system inside the main body cover 1 decreases, making it difficult to read and reproduce thin bars. Therefore, the number of run length data of the white and black bars that the microcomputer 12 captures decreases as the body cover 1 moves away from the barcode. As a result, by constantly monitoring the number of captured run-length data and comparing it with a predetermined threshold value THI, it is possible to detect whether the target is approaching or departing. If the comparison result by the comparison means 17 is equal to or greater than the threshold value TH1, it is assumed that the bar code is approaching and the process branches to the decoding routine, and if the number of captured data is equal to or less than the threshold value TH1, the process branches to the decoding routine. The state branches to a defective check routine for rechecking the status.

In the decoding routine, first, after clearing the counter N indicating the number of departures to ○, the barcode type is determined, and a specified number of characters are decoded.
This result is stored in a first memory serving as a first storage means. This first memory is for storing the current read data.

Here, when the flag=0, the flag is set (flag=1) and the contents of the first memory are transferred and stored in the second memory serving as the second storage means. This second memory is for storing previously read data. Then, the contents of the first memory are transferred to the data processing device 13. In other words, the first
The memory is for storing the decoding results when the decoding results are transferred to the data processing device 13.

However, when the flag = 1, it means that decoding was performed again before the body cover 1 was separated from the barcode, so the second memory that stores the previous decoding result and the new decoding result of this time are The comparison means 18 compares the contents with the first memory to be stored. This comparison means 1
Only when the contents of both memories do not match as a result of the comparison in step 8, the new contents of the first memory are stored in the second memory as the previous contents, and then the contents of the first memory are stored in the data processing device 13. Transfer output to. That is, when a decoding result different from the previous decoding result is obtained (that is, when a different barcode is decoded), the result is distinguished from the double reading and is regarded as valid, and is transferred to the data processing device 13. It is. Therefore, even when reading a two-stage or multi-stage barcode as shown in FIG. Barcodes 4 can be read continuously.

On the other hand, in the separation check routine, the detection is performed even when the dynamic resolution decreases, such as when the main body cover 1 is moved quickly, or when the barcode 4 moves out of the field of view (opening 1a) of the main body cover 1. The number of data temporarily becomes smaller than the threshold value THI. Even in such a state, if it is determined that the barcode has left the barcode, the same barcode may be read twice. Therefore, in this embodiment, the number of times the defection is branched to the defection check routine is counted and checked by the number detection means 19, and the defection determination means 20 determines that the defection is defective if the defection is not consecutively branched to the defection check routine by a set number of defections TH2. are not recognized. That is, at the beginning of the defection check routine, a counter N indicating the number of defections is incremented by 1, and only when the resulting value of N exceeds the threshold value TH2 as the predetermined number of defections is determined to be an actual defection state. In other words, as the main body cover 1 is separated from the barcode 4, the branch cycle to the separation check routine is repeated this number of times, and the programming timer for skipping this separation check routine is timed up), 1 The previous reading operation is completed so that a new reading can be started. On the other hand, if a branch is made to the separation check routine due to the above-mentioned drop in dynamic resolution, etc., it can be determined that the barcode is approaching at a certain timing, and the process does not branch to the separation check routine a predetermined number of times in a continuous state. It is not considered an actual disengagement motion. Furthermore, since the counter N is always cleared at the beginning of the decoding routine, it is not recognized as an actual defection unless the branching continues to the defection check routine by the threshold value TH2. It becomes highly reliable.

In this way, according to this embodiment, the conventional distance sensor 16
Since it is possible to detect the approaching/separating state of the reading device from the barcode based on the read data without providing a special sensor such as the above, it is possible to reduce the cost and weight of the device. In addition, since the previous read data and the current read data are compared, the current read data can be validated only if the contents are different. barcodes can be read. Therefore, even two-stage or multi-stage barcodes can be read continuously.

In addition, since the defection state is not determined by detecting defection only once, even if there is a pseudo defection state due to a decrease in dynamic resolution, this will not be determined as an actual defection state. There is no need to read the barcode twice during one barcode reading operation.

Effects of the Invention Since the present invention is configured as described above, it is possible to detect the approaching/leaving state of a barcode by utilizing a decrease in reading resolution without providing a special distance sensor, etc. In this case, when the barcode is approaching, the previous read data and the current read data are compared.
If the two are different, the current read data can be validated. Therefore, even in the case of a two-stage barcode, each barcode can be read continuously without separating from the barcode, and the reading Improved workability,
Furthermore, even if a defect is detected due to a pseudo defect such as a decrease in dynamic resolution, it is not considered to be an actual defect unless the branch to the defect check routine is continued a predetermined number of times. It is possible to reliably prevent this.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram showing an embodiment of the present invention in the form of a flowchart, FIG. 2 is a vertical side view including a control block showing a conventional example, and FIG. 3 is a plan view of an example of a two-stage barcode. 17... Comparison means, 18... Comparison means, 19...
Number of times detection means, 2o...Departure judgment means ratio Applicant Tokyo Electric Co., Ltd. 1"

Claims (1)

[Claims] a comparison means for comparing the read data with the barcode recognition setting number; a first storage means for storing the current read data;
a second storage means for storing previously read data; and a comparison means for comparing the contents of the first storage means and the second storage means under the condition that the comparison result by the comparison means is equal to or greater than the set number of barcode recognitions. , a number detection means for detecting the number of consecutive departures from a barcode that branches to a departure check routine when the comparison result by the comparison means is less than or equal to the set number of barcode recognition; A bar code reading device further comprising a separation determination means for detecting the duration of the separation check routine by comparing the above and determining the presence or absence of a separation state.