JPS5849907B2 - Barcode symbol printing quality inspection equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for inspecting print quality in a barcode symbol printing process.

Generally, when printing a barcode symbol, the width of the black bar and white bar of the barcode symbol fluctuates due to changes in printing pressure, ink density, etc. in the printing device. It is necessary to constantly adjust the printing pressure, ink density, etc. in the printing device to the optimum by inspecting the ratio of

Conventionally, this inspection has been carried out using a printability gauge, which will be explained with reference to FIG.

That is, a barcode symbol original plate and a printability gauge original plate are placed side by side in a barcode symbol printing device, and as shown in FIG. Gauge A-A'
~Print K-K'.

In this printability gauge, one section is constructed by combining a pair of equally spaced parallel lines at right angles to each other, and the distance between the parallel lines becomes smaller as the K section is approached.

When inspecting print quality, the degree of contact between parallel lines in a certain section is observed with a magnifying glass, and the ratio of the black bar width to the white bar width of the barcode symbol 1 is estimated by analogy.

In other words, when strict bar width dimensional accuracy is required, for example, observe the gauge K-K' near the K section, and if it is not possible to distinguish between parallel lines, it is determined that the error exceeds the allowable range. However, the printing pressure, ink concentration, etc. in the printing device were adjusted to obtain the bar width dimensional accuracy between parallel lines in the gauge K-K/.

In this inspection method, it is necessary to print a printability gauge near the barcode symbol at the same time as printing it, but printing may be restricted due to design or space considerations. It takes a considerable amount of time and skill to understand the correlation to infer print quality from gauges, and inspection is done visually through a magnifying glass, so it is difficult to accurately evaluate print quality. The drawback was that it required skill and effort to become one.

The present invention has been made in view of these drawbacks, and it is an object of the present invention to provide a device that automatically inspects the print quality of the bar width of a printed barcode symbol and displays the results. .

The present invention focuses on the fact that among bars in a barcode symbol of the same size, there are parts where black bars and white bars, which are standards that should be the same width and constant, are adjacent to each other, The width of at least one adjacent black bar and the width of a white bar are compared, and the print quality can be determined from this comparison value.

Examples of the present invention will be described below.

FIG. 2 shows the configuration of an embodiment of the present invention in a block diagram excluding the bar code symbol scanning mechanism.

In FIG. 2, the barcode scanning mechanism may be the same as the conventional one, and a small reflector 3 is attached to the output shaft of a torque motor 2, which exhibits a rotation angle proportional to the drive current value, and a drive circuit 4 drives It is rotated by a predetermined angle using an electric current.

As a result, a spot beam from a light source 5 such as a laser beam according to the JIS standard is swung at a constant speed, and the barcode symbol 1 arranged on a predetermined scanning area is scanned at right angles to the bar direction.

On the other hand, as a light receiving system, a condensing lens system 6 is disposed in a reflection area of the light beam that scans the barcode symbol 1, and a photoelectric conversion element 7 is disposed at its focal position to convert the scanning reflected light into an electrical signal.

This electrical signal has a black bar with a reflectance close to 0 and a very small amount of light, and a white bar with a reflectance close to 1 and a large amount of light, so when photoelectrically converted, the part corresponding to the black bar has a low level.
The portion corresponding to the white bar becomes a high-level pulse train-like signal.

Numeral 8 is a waveform shaping circuit, and 9 is a digitalization circuit which digitizes the pulse width and pulse interval of the pulse train signal from the waveform shaping circuit 8 in each scanning order, and these data are sequentially stored in the memory circuit 1o. be remembered.

Further, 11 is an arithmetic circuit that reads digital data at a specific address from the memory circuit 1o and performs a predetermined arithmetic operation, and 12 is a display device that displays the result of this arithmetic operation.

Usually, these are housed in one housing.

Next, the operation will be explained with reference to FIG. 3, which shows the bar code symbol to be scanned and the input/output signal waveforms of each part in FIG. 2.

Barcode symbol 1 (Figure 3a) usually consists of two black bars on the starting side and a white bar between them, a left guard par LG, and a similar right guard bar RG on the ending side. , has three white bars in the middle and a center bar CG that is wider than the two black bars between them, and the widths of these white bars and black bars are all equal, and the black bar is wider than the other black bars. It is set to be long.

In addition, there are standards for the size of barcode symbols, but here we will use JIS (B-9550)
Standard version of AN code (59 lines per bar)
Explain the barcode symbol.

A triangular wave or a sine wave is supplied to the torque motor 2 (in the case of a sine wave, the reflector 3 is rotated so as to scan the barcode symbol 1 with its substantially straight portion), and the spot beam moves the barcode symbol 1 to the left guard bar LG. Have them swing the bar in order to scan at right angles in one direction.

This scanning reflected light is condensed by a condensing lens system 6 and converted by a photoelectric conversion element 7 into a pulse train-like electrical signal as shown in FIG. 3b.

This electrical signal does not become a perfect square wave because the spot of the light beam has a certain size, and the pulse width and interval of the intermediate level most closely correspond to the black bar width and white bar width. Therefore, the waveform shaping circuit 8 shapes the signal into a signal having an intermediate level pulse width and interval as shown in FIG. 3C.

Simply put, the digitization circuit 9 is an A-D conversion circuit,
The number of periods of a constant period clock pulse that each pulse width and interval in the signal shown in FIG. 3C corresponds to is output as binary information.

In order to achieve this, for example, in the case of a pulse width, a clock pulse from a clock pulse generator that generates a pulse with a predetermined constant period and the signal shown in Figure 3C are input into an AND circuit. Since this AND circuit outputs a clock pulse only while the C signal in FIG. 3 is at a high level, it is sufficient to count each pulse with a counter.

When measuring pulse intervals, an AND circuit and a counter may be provided separately, and the signal C in FIG. 3 may be input to the AND circuit through an inverter.

In this way, the digital data indicating the respective widths of all black bars and white bars in barcode symbol 1 is such that the first black bar data of the left guard bar is stored at address 0 of the memory circuit 1o, and the next white bar data is stored at address 0 of the memory circuit 1o. The data are stored in the memory circuit 10 alternately in scanning order, such as address 1.

By the way, as mentioned above, the white bar width and the black bar width in the left guard bar LG, center bar CG1, and right guard bar RG of barcode symbol 1 must be constant and equal, and due to unadjusted printing pressure, ink density, etc. , as the width of the black bar becomes thicker, the width of the white bar becomes thinner,
Since this variation occurs uniformly across the entire bar, printing accuracy can be determined by comparing the white bar width and black bar width of any of these sets, and in this example, this is This is done using three white bars and two black bars.

In this case, since the number of dots in barcode symbol 1 is determined to be 59 in total for white and black, daisycle data CTW1, CTW2, CTW3 is stored at addresses 27, 29, and 31 of the memory circuit 10, and contains data CTB1 and CTB2 representing the black bar width of the center bar CG as shown in FIG. 3 d1.
are stored at addresses 28 and 30 of the memory circuit 10.

The arithmetic circuit 11 calculates that when the digital data of all bars of the barcode symbol 1 is stored in the memory circuit 10,
The daisicle disks at addresses 27 to 31 of this memory circuit 10 are read out and the following calculation is performed.

If the white bar width and black bar width in the Senku bar CG are equal, the calculation result will be 0.5, which indicates the standard value. For example, if the calculation result is 0.4, the black bar width will be 0.4 and the white bar width will be 0.4. Since the bar width is at a ratio of 0.6, this indicates that the printing pressure or ink density needs to be increased.

FIG. 4 shows an example of the display device 12, in which the calculation results of the calculation circuit 11 are indicated by an indicator having a scale equally divided between 0 and 1.

Therefore, by adjusting the printing pressure, ink density, etc. of the barcode symbol according to this instruction value so that the instruction value becomes 0.5, it is possible to improve the printing quality.

Note that the above explanation is -fII, and the A-D conversion in the digitizing circuit 9 may be performed using another method, and the display device 12 may be a bar graph display using a linear arrangement of LEDs or the like, or a digital display using a CRT or the like. Various examples can be considered, such as a display, a printed display by a printer, etc.

Furthermore, in addition to the standard code with 59 bars, there is also a shortened code with 43 bars in the JAN code.
9 to 23, and for this reason, not only JAN code but also other bar code symbols, such as UPC code and EAN code, have white bars and black bars, which are the standards that should have a constant width. Therefore, the print quality can be inspected in the same way.

Of course, the computation for comparison is not limited to the expressions in the example.
For example, you can compare one white bar and one black bar, or you can also compare left or right guard bars.

Furthermore, the present invention is not limited to barcode symbols obtained by printing with a rotary press or the like, but can also be applied to barcode symbols obtained by impact type printing.

As is clear from the above description, according to the present invention, the accuracy of bar width, which is the most important factor in print quality, can be inspected simply by setting a printed barcode symbol label in a predetermined position. By adjusting the printing pressure, ink density, etc. of the printing device accordingly, it is possible to always provide barcode symbols with optimal print quality.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining a conventional barcode symbol printing quality inspection method, FIG. 2 is a block diagram of an embodiment of the printing quality inspection device according to the present invention, and FIG. FIG. 2 is a diagram showing the relationship between the input and output signal waveforms of each part, and FIG. 4 is a diagram showing an example of a display device. In the figure, 1 is a barcode symbol, 2 is a torque motor, and 3
4 is a reflecting mirror, 4 is a drive circuit, 5 is a light source, 6 is a condensing lens system, 7 is a photoelectric conversion element, 8 is a waveform shaping circuit, 9 is a numerical circuit, 10 is a memory circuit, 11 is an arithmetic circuit, 12 is display device.

Claims (1)

[Claims] 1. A device for inspecting printing quality in a printing process of a barcode symbol by comparing a white bar width and a black bar width, which should serve as a standard, comprising: means for automatically scanning the barcode symbol with a light beam; means for receiving reflected light and converting it into an electrical signal; means for obtaining digital data corresponding to each bar width in the bar code symbol and digital data corresponding to each black bar width from the electrical signal; At least one digital data corresponding to a predetermined white bar width and one digital data corresponding to a black bar width are extracted from the data, and predetermined calculations are performed to determine the white bar width and black bar width. A barcode symbol printing quality inspection device having a step for calculating a ratio between the two and a means for displaying the same.