JPH0668294A - Scanning direction detecting method for bar code label - Google Patents

Abstract

PURPOSE:To detect a scanning direction along the arranging direction of a bar code appropriately even when a bar code label is shifted obliquely. CONSTITUTION:Black picture elements S1-S8 on the reference line 10A of a screen 10 are detected, and closed loop L1, L2,...L7 length for each picture element are found. Also, edge coordinates A, B, C, and D, etc., on those closed loops are detected. Thence, inspection scanning lines alpha, beta' parallel-displaced from two kinds of straight lines intersecting orthogonally to each other passing the edge coordinates are found, and also, the maximum bar intervals K1, K2 are found from respective inspection scan operation, and the inclination of the straight line which supplies a smaller interval is recognized as the scanning direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of reading a multi-stage bar code label, and more particularly to a bar code label array direction for automatically detecting the bar array direction when the bar code label to be read is tilted. It relates to a detection method.

[0002]

2. Description of the Related Art Commonly used bar code labels are
Usually, the entire size is standardized to have a fixed length and width, and black bars and the like are recorded on the label in a state in which they are arranged in a line with various widths and intervals. Also,
Since the amount of information to be recorded is not so large in this barcode label consisting of one row and one line, a multi-layered barcode in which the barcodes are stacked in several rows has also been developed, and it is possible to record many pieces of information. You can do it. On the other hand, as bar code readers for reading these bar code labels, in addition to the handy type that can be used by grasping with one hand, a stationary type that is fixed at a predetermined position has been developed. By the way, in this stationary bar code reader, the reading light emitted from the reader body is generally projected and scanned while being limited to a certain range. In many cases, the sticking position of the bar code label is preset to a predetermined position on the object.

[0003]

However, in such a bar code reader, even if the bar code label is stuck at a fixed position, the mounting state of the bar code reader is inclined or the packaging box or the like is deformed. Then, the barcode label may not be read accurately or may not be read. Therefore, in view of the above-mentioned conventional drawbacks, the present invention provides a barcode label arrangement direction detecting method capable of reliably reading barcodes even if the barcode label sticking positions are displaced or dislocated. The purpose is to do.

[0004]

That is, the present invention is a method for detecting a scanning direction of a bar code label for detecting the scanning direction of a multi-level bar code label, wherein an image of the multi-level bar code label is picked up and the screen is displayed. For each reference black pixel located on the reference line, the length of a closed loop formed by connecting the black pixels to return to the reference black pixel is detected, and the positions of the farthest black pixels on the closed loop are indicated. End coordinates are detected, two kinds of straight lines which pass through adjacent two points of the four end coordinates on the closed loop which are the maximum in the closed loop length and are orthogonal to each other are calculated, and each of these straight lines is calculated. Calculate a straight line when a small amount is translated in a certain direction and set it as an inspection scan line.The maximum bar interval is detected for each of these inspection scans, and the smaller of the maximum bar intervals is given. The can is intended to recognize as a scanning direction of a multi-stage bar code label.

[0005]

According to the present invention, a closed loop that follows a path corresponding to each bar or the outer frame of the bar is detected, and two kinds of four end coordinates on the closed loop, which are adjacent to each other and are orthogonal to each other, are detected. Are calculated and the straight lines obtained by parallel translation of these straight lines in the direction in which the bar code exists are set as inspection scanning lines, and the maximum bar interval is detected by the inspection scanning in these two directions. The inclination of the straight line that gives the smaller maximum bar interval is recognized as the scanning direction in the multi-stage bar code label.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a flow chart showing a scanning direction detecting method of a barcode label according to the present invention, and this scanning direction detecting method is composed of first step to sixth step 6. In the first step 1, a predetermined image pickup means, for example, a CCD camera (area sensor) picks up an image so that the entire image of the multi-stage bar code label fits within the screen 1 shown in FIG. Then, the bar code label is imaged in such a state that it both belongs to the upper and lower divided areas SI and SII that are bisected by the center line 10A of the screen 10. In addition, here, the origin 0 is set at the upper left corner of the screen 10,
In addition, the orthogonal coordinates are set with the horizontal and vertical sides passing through the origin 0 as the x and y axes. In a second step 2, on the screen 10 shown in FIG. 3, (called hereinafter this with reference black pixels) a black pixel that is on the center line 10A as a pixel immediately before is a white pixel S ₁ to S ₈ detected,
Closed loop L ₁ , l ₂ ~ for each reference black pixel S ₁ ~ S ₈
l _6, to detect the length and the four end coordinates of the L _7. Here, the closed loop means, for example, with respect to the first reference black pixel S ₁ , a substantially rectangular figure that connects a number of black pixels that are adjacent to this point S _{1 and} are continuous in succession (this is outside the multistage bar code). (Corresponding to a frame). The length of the closed loop L ₁ with respect to the first reference black pixel S ₁ is, for example, in the divided area SI occupying the upper half of the screen 10, for example, in the first closed loop L ₁ , starting from the starting point S ₁ and providing a white pixel on the left hand. At the same time as it moves clockwise toward the adjacent black pixel, at the same time, it moves counterclockwise toward the adjacent black pixel while facing the white pixel in the right hand in the divided area SII occupying the lower half of the screen 10. It is the total value of the two route lengths when the two arrive at the same end point S ₇ .
The end coordinates detected for each closed loop are, for example, for the first closed loop L ₁ , the four most distant points A, B, C on the closed loop L ₁ in the x and y axial directions.
It means D. In the third step 3, the maximum closed loop (first and seventh closed loops in this embodiment) among the closed loop lengths obtained in the second step 2 is searched for, and the four end coordinates A on this closed loop are searched. , B, C, D are detected. However, here A (A _x , A _y ), B
_{(B x, B y),} C (C x, C y), D (D x, D y)
And In addition, in the third step 3, two adjacent coordinates among these end coordinates, for example, A as shown in FIG.
Two kinds of straight lines α and β that pass through B and AD and are orthogonal to each other, that is, α: (A _x −B _x ) · (y−A _y ) = (A _y −B _y ) · (x−A _x ) β _{: (a x -D x) ·} (y-a y) = Request _{(a y -D y) · (} x-a x).

In the fourth step 4, the two types of straight lines α and β obtained in the third step 3 are translated by a small amount in the direction in which the bar code exists. For example, with respect to the straight line α, the following straight line α ′ is obtained by moving −Δy in the y-axis direction,
This is an inspection scan line. α ′: y = [(A _y −B _y ) / (A _x −B _x )] (x−A _x ) + A _y + Δy Similarly, for the straight line β, move + Δy in the y-axis direction to The straight line β'shown in (1) is obtained and this is also used as the inspection scanning line. β ′: y = [(A _y −D _y ) / (A _x −D _x )] (x−A _x ) + A _y −Δy In the fifth step 5, the straight line α ′ obtained in the fourth step 4 is obtained. , Β ′, and the maximum bar intervals K1 and K2 respectively obtained by these scannings are determined. Then, a straight line which gives the smaller of the maximum bar spacing K1, K2 of both the inclination of the (beta 'in this example) (in this example _{[(A y -D y) / (} A x -D x) ]
Can be recognized as the scanning direction of the multi-stage barcode label. Therefore, according to this embodiment, the path length is independently measured separately on the upper and lower surfaces of the screen 10 divided into two, and it is possible to confirm that the same point has been reached at the same time. The path length can be measured.

[0008]

As described above, according to the method for detecting the scanning direction of the bar code label according to the present invention, attention is paid to the black pixels on the screen reference line, and the black pixel on the screen reference line is used as a reference to detect the outside of the bar or the bar code. The length of the closed loop along the frame is detected, the coordinates of the four ends on the closed loop are detected, and a straight line that serves as a reference when performing each inspection scan through these coordinates is set, and the set straight line is set. Of the maximum bar spacings obtained by each inspection scan along, the inclination of the straight line that gives the smaller one can be automatically recognized as the scanning direction of the multi-stage bar code label, so it is affixed with a skew. It is also possible to automatically read multi-stage bar code labels.

[Brief description of drawings]

FIG. 1 is a flowchart showing a scanning direction detecting method for a barcode label according to the present invention.

FIG. 2 is an explanatory diagram showing setting coordinates and the like on a screen used in the detection method shown in FIG.

FIG. 3 is an explanatory diagram showing a closed loop on an imaging screen used in the detection method shown in FIG. 1.

FIG. 4 is an explanatory diagram showing inspection scanning lines used in the detection method shown in FIG.

[Explanation of symbols]

10 screen α ', β'inspection scanning line S _{1 to} S ₈ reference black pixel A to D edge coordinates K1, K2 maximum bar interval

Claims (1)

[Claims] 1. A method for detecting a scanning direction of a bar code label for detecting a scanning direction of a multi-level bar code label, wherein an image of the multi-level bar code label is picked up, and each reference black pixel located on a reference line of the screen. In addition to detecting the length of the closed loop, the four edge coordinates indicating the farthest black pixel positions on the closed loop are detected, and the four edge coordinates of the closed loop having the maximum length of the closed loop are detected. Two kinds of straight lines that pass through two adjacent points among them and are orthogonal to each other are calculated, and the straight lines when the respective straight lines are moved in parallel in a certain direction by a small amount are calculated and set as inspection scanning lines. A bar code label characterized by detecting the maximum bar interval in each inspection scan and recognizing the inclination of the straight line that gives the smaller of the maximum bar intervals as the scanning direction of the multi-stage bar code label. Scanning direction detection method.