JPS59198156A - Method and apparatus for detection of inferior printing part in rotary printing - Google Patents

Abstract

PURPOSE:To detect inferior printing parts such as ink streak and others, by detecting the difference of signal by light output such as the difference of densities at coresponding 2 positions of repeated pattern existing in the same phase of print or the like. CONSTITUTION:The corresponding same position of repeated pattern P existing in the same phase of print is successively scanned with a line sensor at 2 positions L1 and L2 spacing the gap of integral times circumference of plate cylinder facing in the travelng direction of print. The signal part P1 influenced by streak T is changed to the signal P2 not influenced thereby and the output signal corresponding to the signal P3, the difference of levels of both signals, is converted to external output to give the alarm.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a 1i11J for rotary presses such as gravure rotary printing presses.
The present invention relates to a method and apparatus for detecting defective printing areas such as ink streaks that sometimes occur on the surface of printed paper, plastic film, etc. when rotary printing is performed using a machine.

Currently, all gravure printing is performed using cylindrical rotary printing, except for special cases.

A large amount of flexible ink (C) is applied to the surface i/i7 of the cylinder by an ink roller, and this is scraped off from the printing plate by an ink scraping plate called a doctor, and the ink remains in the recesses of the printing plate. Printing is performed by transferring it to the surface of paper or the like [see Figure 3].

In this case, lumps and fine dust may sometimes get into the area where the doctor scrapes off the surface of the plate cylinder. ! I; As shown in the partial enlarged view of the ink scraping part of the doctor in Figure 2, there is no dust or other particles between the tip of the doctor blade (2a) that is in contact with the surface of the plate cylinder (1) and the circular surface. Particles (G) enter, usually 01
The thin cutting edge made of a mild steel plate with a thickness of about 5 to 0.3 mil is partially lifted, which causes ink to be scraped off poorly. ) is left behind, and as the IL plate cylinder rotates, ink streaks (1) are generated linearly on the surface of the sheet (S) printed with a continuous repeating pattern (P) as shown in Figure 1. In FIG. 2, (C) shows the recesses on the cylindrical plate surface, and (I) shows the ink remaining in the recesses.

However, the feeding speed of the printed material is fast, 3 to 5 meters per second, and since these streaks do not appear continuously, they pass instantly and are difficult to detect. There was no other way to discover it than by visually inspecting the printed matter.

The present invention has been made in view of these points, and is installed in the path during each single color printing such as gravure printing, and automatically removes defective printed areas such as streaks caused by poor scraping of the doctor. The purpose of this paper is to provide a method and device for detecting defective prints by general rotary printing.

Hereinafter, embodiments of the present invention will be explained based on the accompanying drawings.

Figure 3 is a block diagram showing the overall system of a device for detecting defective printed areas such as ink streaks in gravure printing according to the present invention. be.

In the figure, reference numeral 11) is a plate cylinder with a plate surface formed by corrosion around the entire circumference, which rotates in contact with an ink roller (11) whose lower surface is immersed in an ink reservoir (14) located below, and which has a flexible plate surface. A large amount of ink m is applied by the ink roller, and the plate cylinder rotates to rotate the blade (2) of the doctor (2).
All the ink on the mirror surface that is not subject to corrosion is scraped off by the tip of a), and the ink remains only in the recesses that are subject to corrosion. The ink is transferred to the surface of the sheet (S), such as paper or plastic film, which is sandwiched and fed between the sheets and printed. The sheet (S) marked 1ii11 changes its direction by the guide roller (+5) and enters the drying section facing -1, but along the traveling path of this sheet (S), the circle of the plate cylinder Fluorescent lamps or other illumination lamps (3a) with a length that is an integer multiple of the circumference [at two locations with the diameter of the cylinder and illuminate the running path in a perpendicular direction.

(3b) is provided at each position (S)
It seems to illuminate the printed surface. Furthermore, across this traveling path in the direction of right angles, there are vertical planes (r-+) with an interval of two strokes as shown in "-", (on r-J, C, C, C, C, C, C, C, C,
It is equipped with a light receiving section such as D, and an optical system such as SELFOC is installed in front of it.A line sensor is installed as an imaging means, and an illumination lamp is installed to capture the reflected light on the illuminated printed matter surface. I am starting to receive it. In this case, the imaging means may be a multi-lens system in which a single lens and a number of combinations of C, C, and D are lined up in a straight line, or a lens system and a vidicon may be used. In addition,
Figure 4 shows the main part when using the self-otter method as a line sensor, and shows the state in which C, C, and D are adhered to the imaging plane of selfocs (lO) arranged in a straight line. .

(41)) Ktr;J: Synchronization from the same concave signal generator (5) such as a
#S117IJ section (6a).

(61)), and each line sensor is configured to simultaneously scan the same corresponding position on the print surface. Same size of printed matter ([1
Each image sweeper performs 11 [[primary scans] at the same position corresponding to the repeating pattern in the image.

The outputs from these line sensors (4a), (41)) are input to a comparison/judgment unit (8) consisting of an 11J arithmetic amplifier via amplifiers (7a) and (7b), respectively, and are then input to a comparison/judgment unit (8) consisting of an 11J arithmetic amplifier. It is configured to detect the difference in level and output a signal, and this signal is converted to an external output such as an alarm (9). I'm here.

In this case, the external output is not limited to a buzzer, an alarm lamp, etc., and can be used as appropriate.

Next, the function of detecting defective printed parts such as streaks according to the present invention will be explained.

(7) The 7F points (Zl) and (Z2) of 1- correspond to each pattern in Fig. 3. When the plate cylinder (1) rotates, ink is applied to the cylinder surface by the ink roller (11). The applied and excess ink is scraped off by the doctor (2), and the paper,
For example, as shown in FIG. 1, a pattern TP) is continuously printed on a traveling sheet (S) such as a plastic film. That is, a pattern (P) having a pitch of 7rD, which is the same length as a circle with a diameter ff)), is printed continuously and is directed upward by a guide roller (15) as shown in FIG. At this time, the circle vice-length 7 is facing the running surface of the printed matter.
'The line sensors (4a) and (+b) provided at an interval of an integral multiple of CD scan the sheet (11) at the same position of the pattern in the same phase of the continuous repeating pattern, that is, in the running direction of the sheet (S). do. In this scanning, as described in the above configuration, each line sensor scans the same corresponding position of each pattern (P) in synchronization. Figure 6 shows the relative position between each scanned pattern (Pi) and the scanning point, and shows the (L,) line and (r,) line (8) - representing the scanning area with an interval of 2πD. The line (1) shows the scanning position as shown in figure (b).In this case, the signal output of each line sensor (4a), (4b) obtained by scanning is , are the same because they are the outputs of reflected light from the same part of the pattern.

Next, as mentioned earlier, mark the lumps etc.
When a streak of ink is generated on the surface of an object, the streak ff+ first passes through the front surface of the first line sensor and then through the front surface of the second line sensor (4b). , a continuous repeating pattern (P) [only the d frame is shown in the figure and the internal pattern is omitted] and the -''- streaks of the pattern (the relationship between the scanning position and the streaks when the sword passes in front of the line sensor) In the figure, (L, ) and (L2) indicate the scanning position of each line sensor, and from figure (a) to figure (e), the streak (T') is the scanning line. In the state shown in Figure (A), the line (11 is still the line) At this time, the output signal from the (Ll) section, which is the output signal obtained by scanning the line sensor (4a), is shown. signal table,
The signal from section (T-2), which is the output signal obtained by scanning the line sensor (4b), was changing at the same level, but as shown in Fig. The (pl) signal part in the (L,) part signal that is affected changes with respect to the (p2) signal in the (L2) part signal that is not affected by it.In the case of the figure, the signal level In addition, these output signals are each input to an amplifier (7a) as shown in FIG.

It is input to the comparison/judgment section (8) via the amplifier (7b), and the 2
The output signal corresponding to the signal (p3), which is the difference in level between the two signals, is converted to an external output such as an alarm (9) and issues an alarm. Next, when the position of the stripe (T) reaches the state shown in Figure (C), the signal from the section (L,) and the signal from the section (L2) match, and the difference between the two signals B is just the stripe. (2 swords
When scanning position '1' R (L2) line -11, figure (
As in the case of (b), the alarm (9) will issue an alarm again due to the output signal corresponding to the signal that is the difference between the two confidence levels, and when the sword passes the scanning position (L2) line, The difference between the two signals disappears and the alarm stops.

''-Era, by setting the interval between both line sensors to an integer multiple of the pitch of the repeating pattern, that is, NπD (where N is a regular &), it is possible to detect the presence or absence of a striation (sword). If the sword touches both line sensors while it is running, the signals from both line sensors will be the same as when there are no streaks, and in the case of long streaks,
There is a risk of misunderstanding that the streaks have disappeared.
The longer the distance between both line sensors, the better.

When the streak passes through the first line sensor,
A judgment signal will be issued twice based on the difference in level when passing through the line sensor @2.For example, if you use an alarm buzzer, you will notice this with the first alarm and the second one with the second alarm. All you have to do is mark the line sensor on the printed matter with a brush.

In the explanation given above, only the streaks were explained as printing defects in a repeated pattern, but it goes without saying that even if the streaks are very large, they can also be detected in the same way.

Regarding detection alone, detection can also be performed by visually observing changes in the output waveforms of both insensors using a cathode ray tube that displays the time between two events in the comparison/determination section (8).

As is clear from the explanation in section 1-1, according to the present invention, when performing cylindrical rotary printing such as rotogravure printing,
This makes it possible to detect ink streaks and other defective printed areas during printing, which was previously impossible, and allows detection of defective areas that previously required troublesome visual inspection after printing. This can be done automatically during printing, making a great contribution to the product management of printed matter.

In addition, "Kihatsu]" is not in the middle of printing, but is finished. It goes without saying that this method can also be used to detect defective stamps such as streaks on printed matter.

[Brief explanation of the drawing]

Figure 1 shows a continuous repeating pattern with ink streaks.
Figure 2 is a partial enlarged view of the part where the ink is scraped off by the doctor. Figure 3 is a block diagram showing the overall system of a device for detecting defective printed areas such as ink streaks in gravure printing. The figure is a side view showing the main parts of the line sensor when using the self-printing method. A plan view showing each state when moving, a plan view showing the engagement position, and Fig. 7 shows a signal that is the phase difference state of the output signal from each line sensor when the line sensor is detected and the detected difference output. The figure shown is, . Il+... version cylinder, f2] - doctor, (2a)... doctor blade, (3a), (3b) - illumination lamp, (4a)
, (4b) - Line sensor, (5)... Synchronization signal generation section, (8)... Comparison/judgment section, (9) Alarm, (10)... Selfoc, (11)... Ink roller , (C)...concavity in the printing cylinder, (G) - lump particles, m, (1) - ink, (P)... pattern, (katana... ink streaks. Patent applicant) Konan Camera Institute Co., Ltd. and 2 others

Claims (1)

[Scope of Claims] 1. In cylindrical rotary printing, the surface of the printed matter is irradiated by illumination means at two locations spaced apart by an integral multiple of the circumference of the printing cylinder in the running direction of the printed matter. The imaging means and the scanning means perform imaging scanning perpendicular to the running direction of the printed matter, and the signals obtained by this scanning are compared by the comparison and judgment means to determine the density difference between two corresponding locations of the same phase (that is, the repeated pattern) on the printed matter. A method for detecting a defective printed part in rotary printing, characterized by detecting a difference in signals due to optical output such as 2. An interval of an integer multiple of the circumference of a plate cylinder in the running direction of the printed material. 1 illumination means for illuminating the print surface located at two locations, and an image pickup means for each printing at the same location.
a scanning means for synchronously scanning the imaging position; a comparison and determination means for comparing and determining two signals obtained by scanning; and a signal conversion means for converting the signal from the determination means into an external output such as a warning signal; A detection device for a defective printed part in rotary printing, characterized by comprising: 3. The apparatus for detecting a defective printed portion in a rotary flill according to claim 2, wherein the imaging means is a line sensor.