JPS6261176A - Floating slice system for bar code reader - Google Patents

Abstract

PURPOSE:To precisely detect each slope parts of level changes of bar code reading data by setting up a floating slice level on the center of successively adjacent extreme values independently of the characteristics of the bar code reading data. CONSTITUTION:A floating slice level forming part 15 includes an extreme value detecting part 151 for successively reading out the bar code reading data stored in an input data storing part 13 and detecting the maximum value, minimum value and an extreme value point applying the position of each data and a slice level calculating part 152 for finding out two adjacent extreme value points successively, averaging the maximum value and the minimum value and forming a floating slice level. Since the floating slice level Sf' is applied by the average value of two adjacent extreme values, the level Sf' is precisely set up on the intermediate level of the continuous values from maximum value to minimum value or the continuous values from the minimum value to the maximum value and is not influenced by the bar width of the bar code or the size of change. Consequently, precise bar width can be detected.

Description

[Detailed Description of the Invention] [Summary] This is a floating slice method for accurately extracting bar width information from a barcode reading signal, which sequentially detects maximum and minimum points in the signal, and extracts bar width information from each adjacent maximum point. The slice level between and the minimum point is set to the average value of the maximum value and minimum value of each point. These are executed by digital processing.

[Industrial application field]

The present invention relates to a floating slicing method for barcode reading signals in a barcode reading device.

[Conventional technology]

In conventional barcode reading devices, barcodes are scanned by a barcode scanner such as a CCD sensor, and the resulting multivalued barcode reading signal is sliced by an analog floating slicing circuit to correspond to the bar width. A binary signal is generated.

In an analog type floating slice circuit, the value of the internal time constant circuit is set so that the floating slice level follows the peak of the input signal at a level slightly lower than that.

FIG. 7 shows an example of generation of floating slice levels by such a conventional floating slice circuit. In the figure,
Vi represents a barcode reading signal, and Sf represents a floating slice level.

Therefore, in a floating slice circuit, once the value of the time constant circuit is fixed, the floating slice characteristics are also automatically fixed, so it may sometimes be impossible to follow areas where there are sudden changes in bar width. there were.

To explain using the example of Fig. 7, in the case of the example shown in Fig. 2, the peak P
o, P +, P z, P 3 correspond to the positions of the black bars.

A wide white bar exists between P,,P,. Therefore, the slice level is S between +PO2PI.

decays with a predetermined time constant and drops considerably at position P. Furthermore, there is a narrow white bar between P, Pg, and the valley is shallow. As a result, P.I.

and P2 are sliced together and are recognized as one black bar, causing an error.

[Problem that the invention seeks to solve]

Conventional barcode reading devices use analog floating slice circuits, so they may not be able to track large changes in the barcode bar width, reducing reading accuracy and greatly impacting system reliability. There was a problem of giving

[Means for solving problems]

The present invention provides a floating slicing method that can always set an appropriate slice level by following a barcode reading signal without being affected by the magnitude of change in the bar width of a barcode.

Therefore, the present invention detects points having local maximum values and local minimum values (hereinafter referred to as extreme value points) from a barcode reading signal obtained by a barcode scanner.

The average value of the values between two adjacent extreme points is determined in sequence, and that value is used as the slice level between the two extreme points.

FIG. 1 is a diagram showing the basic configuration of the present invention.

In fig.

Reference numeral 12 denotes an A/D converter, which converts a multi-level analog barcode reading signal obtained from a barcode scanner (not shown) into a digital signal.

Reference numeral 13 denotes an input data storage section, which stores A/D-converted barcode reading signals in chronological order.

Reference numeral 15 denotes a floating slice level generation unit, which sequentially reads barcode reading data stored in the input data storage unit 13 and generates local maximum values and local minimum values.

An extreme value detection unit 151 that detects the extreme value point that gives the position.
Then, take two adjacent extreme points in sequence.

It includes a slice level calculation unit 152 that averages the maximum value and the minimum value (or the minimum value and the maximum value) to generate a floating slice level.

16 is a slice processing unit, which uses the floating slice level generated by the floating slice level generation unit 15,
The barcode read data read from the input data storage section 13 is sliced.

The floating slice level is updated at each extreme point, so
The same slice level is applied between extreme points.

The sliced barcode reading data is I+IJj
It is output as binary data representing the next bar width.

[Effect]

The operation of the present invention will be explained using FIG. 2.

FIG. 2 illustrates changes in floating slice levels generated when the present invention is applied to barcode read data.

In the figure, ■,' are digitized barcode reading signals, S,' are floating slice levels, A to H are extreme values indicating the maximum or minimum value, and tA to tl (are the extreme values A to H). This is the extreme point.

Since the floating slice level Sf' is given by the average value of two adjacent extreme values, the floating slice level Sf' is given by the average value of two adjacent extreme values.
It will look like this:

One section, one dish, tΦ slice level Sf'tA-t
m (A+B)/2t, -tC(B+C)
/2 t c t D (C+ D) /
2t, -t, (D+E)/2t, -t,
(E+F)/2tr jc
(F +G) / 2ti, -tH (c + H) /
2 In this way, the floating slice level Sr' is reliably set at a level between successive local maximum values and local minimum values, or between local minimum values and local maximum values, and is not affected by the bar width of the barcode or the magnitude of its change. Therefore, it is possible to accurately detect the bar width.

〔Example〕

FIG. 3 is a block diagram of one embodiment of the present invention.

In the figure, 10 is a barcode scanner, 11 is an amplifier, 12 is an A/D converter, 13 is an input data storage unit, and 14
15 is a smoothing processing unit, 15 is a floating slice level generation unit, and 16 is a smoothing processing unit.
17 is a slice processing unit, 17 is a bar width data storage unit, 151
1 is an extreme value detection unit, 152 is a floating slice level calculation unit, 1
53 represents an extreme value storage section.

The barcode scanner 10 is composed of, for example, a CCD sensor, and scans the barcode surface to output a barcode reading signal whose amplitude changes depending on the reflection level of the black and white bars.

The barcode reading signal is amplified to an appropriate level by an amplifier 11, and then sampled and analog-to-digital converted by an A/D converter 12.

They are sequentially stored in the input data storage unit 13 (hereinafter).

(referred to as barcode reading data).

The smoothing processing unit 14 is activated only when recognition of a barcode fails, and in order to remove spike-like noise in the barcode read data stored in the input data storage unit 13,
Performs data smoothing processing (details will be described later).

In the floating slice level generation section 15, an extreme value detection section 151
All extreme values and extreme points are detected from the barcode read data in the input data storage section 13, and the extreme value storage section 1
53, the floating slice level calculation unit 152 calculates the average value of the extreme values of each two adjacent extreme value points to obtain a floating slice level, and the floating slice level is stored in the extreme value storage unit 153 and then processed for slice processing. 16. Note that when detecting extreme values, it is desirable to set a constant dark value and make a determination in order to ignore small fluctuations.

The slice processing unit 16 reads the barcode read data at successive positions (sampling positions) according to the two time series from the input data storage unit 13, and each time the position of the extreme point stored in the extreme value storage unit 153 comes, , update the slice level and execute the slice.

The slice results are binarized for each position (white - ○).

black=1) and stored in the bar width data storage section 17, and used for barcode recognition.

Next, the functions of the smoothing processing section 14 will be explained.

Barcode reading devices are affected by noise such as dust, scratches, and diffused reflections on the barcode surface.

Part of the black band is cracked, and some of the white band has spikes.

Each had the drawback of being incorrectly identified as a thin white bar or a thin black bar.

If the barcode recognition based on the bar width data in the bar width data storage unit 17 results in an error that the corresponding code does not exist, the smoothing processing unit 14 smoothes the barcode read data stored in the input data storage unit 13. Based on this.

To cause floating slice level generation and slice processing to be redone.

FIG. 4 is an example of noise present in barcode reading data, where NI represents a crack and N2 represents a spike.

The smoothing processing section 14 is a type of digital filter having a low-pass filter function, and is realized by, for example, successively extracting data at a plurality of consecutive positions from the barcode read data as a set and taking a simple moving average.

In FIG. 5, this was applied to data at each of four consecutive positions. This is an example of smoothing processing, and Figure 2 (al represents the data before smoothing; Figure 1 (b) represents the data after smoothing. In the figure, indicates the sampling position, and ■ indicates the barcode line at each sampling position k. represents the level value of the acquired data.

Further, vk' is the moving average value given by a quadratic equation.

Vk' = (Vk-H+Vk+Vy day +
vk+2) Next, an actual example of floating slice level generation by the floating slice level generation section 15 is shown in FIG.

Figure (al is barcode reading data V, waveform 1 diagram (bl
Figure 1 (C) shows the extreme value point, its data value, Figure 2 (d) shows the floating slice level, and Figure (e) shows the bar width data of the slice result.

〔Effect of the invention〕

According to the present invention, since the floating slice level is set at the center of sequentially adjacent extreme values (maximum value and minimum value) regardless of the characteristics of the barcode read data, the level of the barcode read data changes. It is possible to provide a stable and highly reliable barcode reading device that can reliably detect each slope portion of the barcode.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the basic configuration of the present invention, FIG. 2 is an explanatory diagram showing an example of floating slice level generation according to the present invention, FIG. 3 is a diagram showing the configuration of one embodiment of the present invention, and FIG. 4 is a bar code. A waveform diagram showing an example of noise existing in read data, FIG. 5 is an explanatory diagram of an example of smoothing processing, FIG. 6 is an explanatory diagram showing an actual example of floating slice level generation according to the present invention, and FIG. 7 is a conventional circuit. FIG. 3 is a waveform diagram showing an example of floating slice level generation according to FIG. In Figure 1. 12: A/D converter 13: Input data storage section 14: Smoothing processing section 15: Floating slice level generation section 151: Extreme value detection section 152: Floating slice level calculation section Patent applicant: Patent attorney, Utsutsuk Electronic Industry Co., Ltd. Hase's Fumihiro (2 others) 41 Tani's 4v1 unit 5J
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Claims (2)

[Claims] (1) The barcode reading device includes an A/D converter (12) that converts an analog barcode reading signal output from a barcode scanner into digital barcode reading data, and a digital barcode reader. An input data storage unit (13) that stores data in the input order; and a floating unit that generates a slice level for slicing the barcode reading data based on the barcode reading data stored in the input data storage unit (13). A slice level generation unit (15) and a slice processing unit that reads barcode reading data from the input data storage unit (13) in the order of input and performs slicing using the floating slice level supplied from the floating slice level generation unit (15). (16), the floating slice level generation unit (15) reads barcode reading data from the input data storage unit (13),
An extreme value detection unit (151) that detects all local maximum values and local minimum values and extreme value points indicating their positions, and one that sequentially selects two adjacent chronologically of the detected local maximum values and local minimum values. Then, calculate the average value of each two values, and use the obtained average value as the two values corresponding to the original maximum and minimum values.
A floating slice method for a barcode reading device, comprising a floating slice level calculation unit (152) that outputs a slice level between two extreme points. (2) In the floating slice method of the barcode reading device described in claim 1, a smoothing processing section (14) is further provided, and when the barcode reading device fails to read a valid barcode, Barcode reading characterized in that the smoothing processing unit (14) smoothes the barcode read data stored in the input data storage unit (13) and redoes the process after generation of the floating slice level. Floating slice method of equipment.