JPH04247457A - Method for monitoring printing quality - Google Patents

Abstract

PURPOSE:To speedily and surely monitor the printing quality of an invisible printing part such as white printing. CONSTITUTION:The printing surface of a traveling print 2 including the white printing is pulsatively irradiated with ultraviolet rays by a light emitting device 3. Then fluorescent agent included in the printing surface is and visible light is emitted so that the other printing surface which does not include the fluorescent agent can be visually and clearly discriminated. Thereafter, it is photographed by a video camera 4 by adjusting timing with the above-mentioned light emission. Then, an obtained video signal is held by a memory 6 by 2-3 seconds which is easily observed. During it, the video signal of the memory 6 is inputted to a monitor display device 1 and made to be an image. Then, it is observed by an operator by eyes.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is in the field of printing quality monitoring, and is concerned with the field of printing quality monitoring. The present invention relates to a print quality monitoring method for monitoring printing misalignment, etc. in printed matter, including white printing to form a paper or desensitized printing to stop color development in a certain portion of carbonless paper, etc.

0002

[Prior Art] Conventionally, checking of printing processing register, checking of printing stains, checking of number/bar code printing, etc. in general printed matter is carried out at a predetermined printing monitoring position of a fixed printing unit that continuously passes. This method is used as a print quality monitoring method in which the printed surface is irradiated with pulses of visible light in time with the passing timing to create a state in which the printed surface appears stationary, and this is then visually observed by a person to perform the above checks. It was. In order to improve this, the present inventor proposes to irradiate visible light pulses at the same timing as above, or to irradiate the printed surfaces of the above-mentioned printing units at a timing that matches this every time the printed surfaces of a plurality of printing units pass. In synchronization with the pulse irradiation of visible light, each time the pulse irradiation is irradiated, a video camera photographs the printed surface at the print monitoring position, and the obtained video signal is sampled and stored in a storage means. and reading out the video signal and inputting it to a monitor display device, thus obtaining a still image of the printed surface at the time to be stored in the storage means,
We have established a print quality monitoring method that visually inspects printing misalignment and other print quality, and have provided an apparatus that executes this method.

0003

[Problems to be Solved by the Invention] Among the conventional methods described above, the former method requires that the person in charge has excellent eyesight and sufficient experience to carry out satisfactory register monitoring. Even for such a person, there is a problem in that it is extremely difficult to continuously perform the above-mentioned direct visual register monitoring work for about 15 minutes or more. The latter method is an improvement on the above method, and is much easier to see than the former method because it uses a monitor display device to obtain a still image of the printed surface of a desired fixed printing unit. This makes it possible to easily and accurately visually check the printing register, check for stains, etc. However, not only with the former method but also with the latter method, it is of course almost impossible to photograph printing that is difficult to visually recognize, such as white printing or desensitized printing, in its original state with a video camera. As a result, the actual situation with this type of printing is that it is not possible to check the printing processing register while the machine is running. Regarding white printing and desensitized printing as mentioned above,
Conventionally, it has been possible to check the print processing register by spraying a special liquid called a desensitization checker to color one of the white printing area and the desensitization printing area, but this method is This method is not suitable for continuous execution following the printing process, and it has the extremely serious disadvantage that it cannot be checked without making the printed matter unusable, making it very difficult to adopt.

In the present invention, the latter method using a video camera and a monitor display device is improved, and printing quality such as print processing registration can be easily improved for printing that is difficult to visually recognize such as white printing and desensitized printing. The purpose is to enable the monitoring of

[0005]

[Means for Solving the Problems] The gist of the configuration of the present invention is to monitor the print quality of printed matter that has an invisible printed area that is difficult to recognize visually and is printed with printing ink containing a fluorescent agent in the printed surface. In the method, ultraviolet light is irradiated on the printed surface of the printed matter that is continuously running at a certain print monitoring position, and the printed surface is photographed with a video camera at a timing to be described later, and the ultraviolet light is irradiated. to obtain a video signal of the printed surface including the invisible printed part that has generated visible light, and the timing is when the printed surface of a certain printing unit of the printed material passes the printing monitoring position, and A video signal of the printed surface photographed at the above-mentioned timing is sampled when a desired number of the fixed printing units pass through the printed surface, and the sampled video signal is held in a storage means until the next sampling is performed. , and the video signal held in the storage means is input to a monitor display device and converted into an image, and the obtained still image is visually observed to monitor the print quality of printed matter having an invisible printed part that is difficult to recognize visually. This is a print quality monitoring method.

[0006] The invisible printed portion is a printed portion that cannot be easily recognized visually, such as white printing, which is printed with printing ink containing a fluorescent agent. Invisible printed areas due to desensitized printing are also indirectly targeted because they are printed in pairs with white printing to mask them. That is, as will be described later, when a white printed surface containing a fluorescent agent is irradiated with ultraviolet light, it emits visible light,
On the other hand, since the desensitized printing surface does not emit this, the boundary becomes clear, and as a result, the printing position can be clearly recognized. The fact that the above-mentioned white printing, etc. contains a fluorescent agent was confirmed by the inventor of the present invention through repeated experiments in which these materials were irradiated with light of various light spectra. This is something that can be learned by coming to understand that a phenomenon occurs. Incidentally, luminescence is said to be a phenomenon in which a substance absorbs energy and re-emits the energy as visible light or electromagnetic radiation in a region close to visible light. It is also theoretically known that in luminescence, the light emitted when excited by irradiation light appears at a wavelength longer than the wavelength of the irradiation light.

[0007] As the ultraviolet light irradiated onto the printing surface, a light spectrum is selected that can efficiently cause the fluorescent agent contained in the invisible printing area such as the white printing to emit light. It is appropriate to irradiate the invisible printing area with various types of ultraviolet light and to experimentally identify the light spectrum with the highest efficiency. As the light source of ultraviolet light, a laser, a xenon lamp, a xenon-mercury lamp, a mercury lamp, a black light, etc. can be employed. For example, in the case of a light source that emits visible light at the same time, such as a xenon lamp, only ultraviolet light in a wavelength band that has been identified as being efficient for the luminescence of the fluorescent agent in the invisible printed area of the target is passed through. It is appropriate to use a filter that cuts out other visible light as much as possible. This is because if the printed surface is irradiated with a lot of visible light at the same time, there is a risk that the difference from other printed parts that do not produce luminescence may become unclear. Furthermore, the irradiation of ultraviolet light onto the printed surface of the printed material may be continuous, of course, but it may be applied at the same time as the printed surface of a certain printing unit passes the printing monitoring position. Pulse irradiation is sufficient. If a xenon lamp or the like is used, pulse irradiation will be performed due to its nature.

[0008] As described above, the video camera may take pictures of the printing surface of a fixed unit of printing that is repeatedly printed, sent out in sequence, and traveling once every appropriate number of passes. This is because the deviation of the printing position and the like does not vary every time a printing unit is printed. In addition, the video signal input to the monitor display device is such that the image of the printing surface of the above-mentioned fixed printing unit can be viewed stationary for a certain amount of time, and in order to eliminate flickering, the same image signal is input for 2 to 3 seconds. This is also because it is preferable that it continues. Furthermore, since printed materials are objects that are moving during the printing process, it is important to take pictures with the shortest possible exposure time in order to obtain blur-free images. or an electronic shutter), or as described above,
A pulsed ultraviolet light source is used to act like a shutter. That is, the printing surface of the target printing unit is shielded from inconvenient ultraviolet light and visible light, and the video camera is kept in the same state as if the shutter is closed, while the above-mentioned A pulse of ultraviolet light is irradiated on the printing surface of a certain printing unit at a certain timing, and the invisible printing area containing fluorescent agent, such as the white printing surface, is instantaneously emitted. It is something that causes a situation. However, in this case, the time during which visible light is emitted from the invisible printing section corresponds to the time during which the shutter is open. During this time, the video camera takes a picture, and the obtained video signal is written into the storage means following the picture taking.

[0009]

[Function] The printed surface of the printed matter that is continuously running is exposed to ultraviolet light when passing near the print monitoring position, or the printed surface of a certain printing unit passes through the print monitoring position. When doing so, irradiation is performed in a pulsed manner every time a desired number of printing units pass through the printing surface in accordance with the timing. When ultraviolet light is irradiated in this way, the fluorescent agent contained in the invisible printing part such as white printing is excited,
It emits visible light and appears white and bright. The printed surface that does not contain the surrounding fluorescent agent naturally does not emit light, so it appears dark and purplish. In this way, the invisible printed portion such as the white printing becomes visually clearly recognizable. Furthermore, if a part of the white printed surface is desensitized, the desensitized printing does not contain a fluorescent agent, but the surrounding white printed surface emits light, so as a result,
At the same time, the desensitized printed surface, which does not emit light, can be clearly recognized visually.

[0010] At the same time, at the printing monitoring position, the printing surface is photographed by a video camera. In other words, when ultraviolet light is continuously irradiated and the running speed of the printed matter is fast, when the printed surface of a certain printing unit passes the printing monitoring position, the Every time a desired number of printing units pass the printed surface, a high-speed shutter is momentarily opened to take a photograph of the printed surface. When ultraviolet light is irradiated in pulses, the video camera does not need a shutter, and it is sufficient to take pictures at that timing. This is because, as described above, in this case, the result is the same as opening the shutter at the moment the pulse of ultraviolet light is irradiated. Further, if the traveling speed of the printed matter is not very fast, there is no need to pulse ultraviolet light and no shutter is necessary. It is sufficient to take a picture at the above-mentioned timing. In this way, the video camera can obtain a video signal of the printed surface including the invisible printed portion, which has generated visible light by irradiation with the ultraviolet light. The video signal obtained above is subsequently written into the storage means, and when the next photographing is performed, it is replaced with the next video signal. The video signal held in the storage means is read out and input to a monitor display device, where it is converted into an image. In this way, still images of the printed surfaces of the printing units that are sequentially photographed and sampled are obtained.

[0011] As mentioned above, on the printed surface of the printing unit, the invisible printed portion such as the white printed surface emits light and appears white, and the other portions naturally do not emit light and appear dark and purplish. It is in a state. However, the invisible printed areas such as the white printed surface are in a state where they can be clearly recognized visually, and the monitor display device can sequentially obtain the printed surfaces of the printed units in that state as still images, and this can be sufficiently displayed. can be observed. Therefore, it is possible to easily visually recognize invisible printed parts such as white printing which are difficult to visually recognize, and to monitor the positional deviation and other print quality.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. First, the apparatus used in the method of this example will be briefly described. As shown in FIGS. 1 and 2, in this example,
A monitor display device 1 that outputs a still image, a light emitter 3 that irradiates pulsed ultraviolet light onto the printed matter 2, a video camera 4 that photographs the printed surface of the printed matter 2, and a sensor 5 that detects the moving speed of the printed matter 2. This is carried out using a memory 6 that holds the video signal of the video camera 4, a controller 7 that controls the video camera 4, the light emitter 3, and the memory 6, and a keyboard 8 that operates the controller 7.

In this embodiment, the target printed matter 2 naturally has an invisible printed portion on its printed surface. Among them, here is printed matter 2 that includes a white printed section.
shall be subject to print quality monitoring. The light emitter 3 has a xenon lamp with a peak emission wavelength of 350 nm ultraviolet light installed inside a box, and a 350 nm
It is configured with a filter that allows ultraviolet light of the previous and subsequent wavelengths to pass through and cuts visible light, etc., and is controlled by the controller 7 to emit light at a predetermined timing, which will be described later. In addition, depending on the relationship with the fluorescent agent included in the white printing, ultraviolet light of the above wavelength was selected from the viewpoint of most efficiently causing the fluorescent agent to emit visible light. The sensor 5 is provided close to the gear of a suitable roller that sends out the printed matter 2 of the printing unit 9, which will be described later, and detects its rotation at a constant pitch, and its output is input to the controller 7.

The video camera 4 is a general video camera equipped with zoom, focus, aperture, and the like. Note that the zoom and focus controls, etc., are performed using the keyboard 8 via the controller 7. Further, the monitor display device 1 is no different from a general television receiver except that it is desired to have as high a resolution as possible. The memory 6 retains a video signal for one screen of the printed surface of the printed matter 2 photographed by the video camera 4 for a predetermined period of time, inputs this to the monitor display device 1, and displays the video signal for the retained period of time. It is for obtaining images. The memory 6 is built into the case c of the controller 7. The controller 7 controls each of the above-mentioned element devices as described below in order to execute the method of the present invention.

Next, prior to carrying out the method of the invention, the above-mentioned group of element devices are first attached to the printing unit 9 for printing the above-mentioned printed matter 2. As shown in FIG. 2, the video camera 4 and the light emitter 3 are installed on a stand 10 at a print monitoring position immediately before the position where the printed matter 2 passes. The position immediately in front of this print monitoring position is either relatively dark or shielded from light. In any case, the aperture of the video camera 4 should be narrowed down to such an extent that the visible light generated on the white printed surface when the light emitter 3 emits pulsed ultraviolet light enters the image sensor for the first time. do. The sensor 5 is also provided close to the gear of a suitable roller for feeding out the printed matter 2 of the printing unit 9. The monitor display device 1 is placed on a case c containing a controller 7 and a memory 6, and is installed at a position adjacent to the printing unit 9. It is assumed that the keyboard 8 is pulled out in front of the case c.

[0016] Then, the printing unit 9 is set,
The operation is started, and the group of element devices described above is operated accordingly. Then, the printed surface of the printed matter 2 that is printed by the printing unit 9 and continues to travel will pass just in front of the print monitoring position. At this time, the sensor 5 first detects the rotation of the gear of the roller that sends out the printed matter 2 of the printing unit 9 at a constant pitch, and inputs a pitch signal to the controller 7. The controller 7 counts the pitch signal to obtain the feed amount of the printed material 2, and detects the position of the printed surface of the printed material 2 passing immediately before the printing monitoring position. Every time the printed surface of a predetermined number of printing units passes through the print monitoring position, the controller 7 sends a drive signal to drive the light emitter 3 at a timing when the printed surface of the printing unit is positioned immediately before the printing monitoring position. The light emitter 3 irradiates the printing surface of the printing unit with ultraviolet light having a peak wavelength of 350 nm. Note that the above ultraviolet light irradiation is 1/
This is pulse irradiation for 100,000 seconds. The fluorescent agent is excited by this ultraviolet light and emits visible light, so that the white printed surface containing visible light appears white and bright. The printed surface that does not contain the surrounding fluorescent agent naturally does not emit light, so it appears dark and purplish. In this way, the white printed surface becomes visually clearly recognizable.

At the same time, at the print monitoring position, the video camera 4 photographs the printed surface, and a video signal of the printed surface including the white printed surface on which visible light is generated by irradiation with the ultraviolet light is obtained. More specifically, first, the emission of ultraviolet light by the light emitter 3 generates visible light on the white printed surface as described above, thereby causing the video camera 4 to essentially open its shutter, so to speak. , the image becomes sensitive to the image sensor. However, the emission of visible light from the white printed surface ends almost immediately when the emission of ultraviolet light from the light emitter 3 stops, although there may be a slight afterglow. It becomes closed. On the other hand, the controller 7
With the control signal, the image pickup device of the video camera 4 is refreshed with a very slight delay in the emission of the ultraviolet light in the light emitter 3, that is, in synchronization with the emission of visible light on the white printed surface. Furthermore, following this, the memory 6 is also refreshed, and the video signals generated in the image pickup device when visible light is emitted from the white printed surface are sequentially written into the memory 6. be. In addition to the above explanation, when photographing with the video camera 4, you can use the zoom function etc. to capture the entire range of the printed surface of a certain print unit, or enlarge a part of it and photograph it as desired. Needless to say, it is possible to adopt the following shooting units, and it goes without saying that other functions can also be used freely. These functions can be used by operating the keyboard 8.

[0018] As described above, when the printed surface of a certain printing unit passes the print monitoring position, one photograph is taken every time the printed surface of a desired number of printing units passes in accordance with the timing. The video signal of the printed surface of the unit is sampled and held in the memory 6, and when the next sampling is performed, it is replaced with the next video signal thus obtained. The video signal held in the memory 6 is read out and input to the monitor display device 1, where it is converted into an image. In this way, a still image of the printing surface of the desired photographing unit at the sampling period is obtained.

On the printed surface of the printing unit, as described above, the white printed surface emits light due to ultraviolet light and appears white;
The other parts naturally do not emit light and appear dark and purplish. Thus, the white printed surface is in a state that can be clearly recognized visually, and the monitor display device 1 obtains this state as a still image at the sampling period, which can be sufficiently observed. Therefore, it is now possible to easily visually recognize the white printed surface, which is difficult to visually recognize, and to monitor its positional deviation and other quality.

[0020]

[Effects of the Invention] According to the present invention, ultraviolet light is irradiated onto a printed surface such as white printing that cannot be easily recognized visually,
The fluorescent agent contained in this is excited to emit visible light, making it clearly distinguishable from other printed surfaces that do not contain fluorescent agents, and the moving image is photographed with a video camera at the right timing with a short exposure time. The obtained video signal is held in a storage means for a certain period of time that is easy to observe, and the video signal in the storage means is inputted to a monitor display device during that time to be converted into an image.
This allows the operator to easily and reliably monitor the print quality even for invisible print areas such as white print that are difficult to visually recognize.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram of one embodiment.

FIG. 2 is a schematic diagram of one embodiment.

[Explanation of symbols]

1 Monitor display device 2 Printed matter 3. Light emitter 4 Video camera 5 Sensor 6 Memory 7 Controller 8 Keyboard 9 Printing unit 10 units c Case

Claims (2)

[Claims] Claim 1: In a method for monitoring the print quality of a printed matter having an invisible printed area that is difficult to visually recognize and is printed with a printing ink containing a fluorescent agent on the printed surface, the method continuously monitors printing at a fixed printing monitoring position. The printed surface of the traveling printed material is irradiated with ultraviolet light, and the printed surface is photographed by a video camera at the timing described later, and the image of the printed surface including the invisible printed part that has generated visible light due to the irradiation of the ultraviolet light is obtained. The signal is obtained, and the timing is when the printed surface of a fixed printing unit of the printed material passes the printing monitoring position, and moreover, when a desired number of printed surfaces of the fixed printing unit pass. Then, the video signal of the printed surface photographed at the above timing is sampled, the sampled video signal is held in a storage means until the next sampling, and the video signal held in the storage means is displayed on a monitor display device. A print quality monitoring method for monitoring the print quality of a printed matter having an invisible print part that is difficult to recognize visually, by inputting data into an image, converting it into an image, and visually observing the obtained still image. 2. The print quality monitoring method according to claim 1, wherein the ultraviolet light is irradiated in pulses in synchronization with the photographing of the video signal.