Method for performing function of pause during printing operation in ink type printing device

The present invention relates to a method of executing a pause function during a printing operation of an ink printing system.

Ink-based printing equipment is used to print in a single color or multiple colors on various materials, such as a material to be printed, which consists of paper, such as a web-like recording carrier. The structure of such ink-based printing equipment is known (see, eg, European Patent No. 0788882). Ink-based printing equipment that operates according to the Drop-on-Demand (DoD) principle has one or more printheads with nozzles provided with ink passages, and the actuators of the printheads are controlled by a printer controller. Ink droplets are formed toward the material web to be printed, and the ink droplets are directed to the material web to be printed to form printing points of the printed image. The actuator can form ink droplets by a thermal method (bubble jet) or a piezoelectric method.

When printing on the material web to be printed, often during the printing operation, for example, to control register quality after printing a print job, or to eliminate problems during post-processing of the material web to be printed. In addition, it is necessary to stop the material to be printed web with the pause function. After restarting the material web to be printed, a defect in the printed image may occur in the web section directly under the print head after the pause function is turned on. Based on the relatively large transfer area of an ink-based printing device, such as an inkjet printing system, especially in the case of color printing, a large number of waste papers will be generated depending on the defects of the printed image due to the pose. The resulting print image defects include print image distortion, color register errors, and trapezoidal print image errors. The causes include the expansion or contraction of the material web to be printed during the pause and the consequent misalignment of the material web to be printed under the print head.

These problems will be described with reference to FIG. Of the printing equipment DRs, the printing unit 1 and the printer control device 2 are shown. The printing unit 1 is arranged along the material web 3 to be printed, and the printing unit 1 has a print bar 4 that supports the print heads 5 located in front of and behind the phase of the material web 3 to be printed. There is. In multicolor printing, for example, one print bar 4 can be provided for each color to be printed. The material to be printed web 3 is sent by the take-up roller 9 so as to pass through the print bar 4. The print bar 4 is provided on a support member provided with a guide roller 8. A rotary position transmitter roller 6 is arranged at the inlet of the printing unit 1, and the rotary position transmitter roller 6 is driven by the material web 3 to be printed and forms a pulse according to the feed motion of the material web 3 to be printed. , Pulses are sent to the printer control device 2 and used by the printer control device 2 to determine when to perform the printing process on the individual printheads 5. The material to be printed web 3 is sent to the rotary position transmitter roller 6 by the drive roller 7 arranged on the upstream side of the rotary position transmitter roller 6.

FIG. 1 shows how the material to be printed web 3 can be affected by the printing unit 1 or the ambient air (atmosphere) through the printing equipment DR in each web division BA, for example, when the printing equipment DR is stopped. Shown in principle. In the web division BA1 between the drive roller 7 and the rotary position transmitter roller 6, the material web 3 to be printed is exposed to the ambient air, and as a result, the material web 3 to be printed due to the humidity of the ambient air. Expansion may occur. The vertical change of the material to be printed web 3 caused by this can be compensated by using the rotation position transmitter roller 6. Similarly, in the web division BA2 up to the printing unit 1 on the downstream side of the rotary position transmitter roller 6, the material web 3 to be printed may expand due to the ambient air. This expansion remains unconsidered by the rotary position transmitter roller 6. This also applies to the web section BA3 located below the printhead 5 of the print unit 1, where the material web 3 to be printed may shrink due to the operating temperature of the printhead 5. Since the material to be printed, the web 3, is exposed to the ambient air, the web division BA3 may expand due to the humidity of the ambient air, especially when the distance between the print bars 4 is large. Both effects overlap. Therefore, the material web 3 to be printed is exposed to various influences around the drive roller 7 to the take-up roller 9, and the influence causes the shrinkage or expansion of the material web 3 to be printed. This can result in the above-mentioned defects in the printed image, especially when the printing process is restarted after a pause during the printing operation.

Therefore, when activating the pause function, the following phenomenon is observed in the material to be printed Web 3: -Temperature difference and humidity difference of the printed material web 3 with respect to the ambient air, which is accompanied by shrinkage or expansion of the printed material web 3. -The temperature difference of the print head 5 with respect to the material web 3 to be printed, which is accompanied by the shrinkage of the material web 3 to be printed.

<p><patcit num="1"><text>European Patent No. 0788882</text></patcit></p>

<p> Therefore, the subject of the present invention is to improve the method of executing the pause function during the printing operation as described at the beginning, and to obtain the printed material web and thus the printed image after the pause function is activated, especially after the printing pause is completed. It is intended to provide those with reduced adverse effects of operating temperature and ambient air.</p>

<p> In order to solve this problem, in the configuration of the present invention, in a method of performing a pause function during a printing operation of an ink printing system, a printing unit including at least one printing device and a print bar for supporting a print head. However, by printing on the material web to be printed and the pause function is activated, the feed speed of the material web to be printed decreases from the speed during the printing operation to a predetermined speed over a predetermined time length, and at that time, the time The length is selected at the bottom of the printing unit of the printing equipment at the end of the pose so that the material web to be printed has the appropriate properties regarding moisture and / or temperature, and after the pose is finished, the material web to be printed is again Accelerate to the speed during printing operation.</p><p> Preferably, when the material web to be printed is compatible with the ambient air in terms of humidity and temperature, the material web to be printed has suitable properties.</p><p> Preferably, after the pause function is activated, the feed rate of the material web to be printed is reduced to a predetermined speed in the pre-process time, and when the pre-process time elapses, the material web to be printed is stopped for the pause time.</p><p> Preferably, after the pause function is activated, the feed rate of the material web to be printed is reduced to a predetermined rate over the entire pause time.</p><p> Preferably, the rotary position transmitter roller arranged on the upstream side of the printing unit measures the feed motion of the material web to be printed, sends the measurement result to the printer control device, and transmits the rotation position transmitter of the material web to be printed. The pre-process time is selected so that the section located upstream of the rollers reaches the printing unit.</p><p> Preferably, two printing devices located before and after the phase are used to print on the material web to be printed, and the division of the material web to be printed, which is located in the first printing device, is the printing of the second printing device. Select the pre-process time to reach the unit.</p><p> Preferably, two printing devices located before and after the phase are used to print on the material web to be printed, and after the pause function is activated, the feed rate of the material web to be printed is set to a predetermined speed over the entire pause time. descend.</p><p> Preferably, the printing unit of each printing device moves away from the material web to be printed after the pause time is activated.</p><p> Preferably, the temperature of the print head of the printing unit of each printing device drops after the pause time is activated.</p><p> Preferably, the material web to be printed is cooled between the printing devices.</p>

<p> According to the present invention, the operation of the pause function reduces the feed rate of the material web to be printed to a predetermined value over a predetermined time length from the operating speed used during the printing operation. The time length can be selected so that at the end of the pause, there is a material web to be printed that has suitable properties for printing with respect to humidity and / or temperature underneath the printing unit of the printing equipment. For example, the material web to be printed is adapted to the ambient air in terms of humidity and temperature.</p><p> Another aspect of the present invention is evident from the configuration described in the dependent claims.</p><p> In the first aspect, after the pause function is activated, the feed rate of the material web to be printed decreases from the operating speed at the time of printing to a predetermined speed over a predetermined time length in the pre-process time, and the pre-process time. After that, the material web to be printed is stopped for a pause time of, for example, 1 min, and then accelerated to the operating speed again.</p><p> In the second aspect, the feed rate of the material web to be printed decreases from the operating speed at the time of printing to a predetermined speed after the pause function is activated, for example, over the entire pause time of 1 min, and again at the end of the pause. Is accelerated to.</p><p> According to the advantages of the method according to the invention, a web section of the material web to be printed that occupies a printable value with respect to temperature and / or humidity is located below the printing unit during and after the pause. That value is the value that the material web to be printed occupies when the material web to be printed is adapted to the ambient air with respect to humidity and temperature.</p>

<figref num="1">The principle of the printing unit of an ink-type printing device is shown.</figref><figref num="2">It is a figure which shows the principle of the twin printing system equipped with two printing devices which print both sides of the material to be printed web.</figref><figref num="3">a to c are diagram showing the relationship between the feed rate of the material web to be printed with respect to the time t in various aspects of the pause function.</figref>

Hereinafter, embodiments of the present invention will be specifically described with reference to FIGS. 1 to 3.

According to the present invention, two modes having different pause functions are realized according to the request of the printing operation of the ink-type printing device or the request of the device for post-processing the material web to be printed in the printing job to be processed. 1. Stopped pose with pre-process time 2. Slow movement pose.

In both aspects of the pose, print quality is improved by reducing defects in the print image described above.

I. Application of the present invention to printing equipment DR (Fig. 1) 1. Stopped pose with pre-process time In the paused state with the pre-process time, after the pause key is activated to interrupt the printing operation, the feed rate of the material to be printed web 3 is set to a predetermined time t before the printing device DR is stopped._vDriving speed v over (b in Figure 3)_dFrom speed v_vDecreases to. For example, the feed rate of the material to be printed Web 3 is t._vFrom 1min to 3min, v_v= It drops to 0.1m / sec ~ 0.3m / sec. As a result, the web divisions BA2 and BA1 are adapted to the ambient air in terms of temperature and humidity, that is, in an equilibrium state in terms of expansion or contraction, and are transported to the lower side of the printing unit 1. Pause time following this t_pThen, the position change of the printing material Web 3 is small enough to be ignored at the maximum. After the end of the pose, underneath the printing unit 1, a section of the material to be printed web 3 that has properties suitable for printing operation with respect to humidity and temperature is located. The material to be printed Web 3 is then operated again at speed v_dIs accelerated to.

2. Slow movement pose In the low-speed movement pause (c in Fig. 3), when the pause key is activated, the speed of the material to be printed Web 3 is the operating speed v._dFrom slow movement speed v_sDecreased to, for example pause time t_pOver v_s= It drops to 0.001m / s ~ 0.0015m / s. In this aspect of the pause function, the material web 3 to be printed does not stop, so that a new material web 3 to be printed is always transported to the printing unit 1, although shrinkage or expansion factors also occur during the printing operation. Since it has already been compensated and is in an equilibrium state, the shrinkage of the printed matter material web 3 due to the temperature difference or the expansion of the printed matter material web 3 due to the humidity in the ambient air does not occur. The slack in the material web 3 to be printed, which may occur on the downstream side of the printing device DR, can be absorbed by the device 13 (FIG. 2) that post-processes the material web to be printed.

II. Application of the present invention in a twin printing system 1. Description of special problems in twin printing system A special problem arises when operating a twin printing system. This problem and its solution will be described with reference to FIG. Figure 2 shows the principle of a printing system DS (twin printer) equipped with two printing devices DR1 and DR2. Of each printing device DR, only the components necessary for explaining the present invention are shown here. The remaining components can be understood from the background technology, as well as the structure of the individual components. FIG. 2 shows the printing unit 1 and the drying unit 10 of the printing equipment DRs. Further, a storage roll 11 of the material web 3 to be printed (the material web 3 to be printed is conveyed from the storage roll 11 toward the first printing device DR) is shown between the printing device DR1 and the printing device DR2. The turning unit 12 and the rotation position transmitter roller 6 are illustrated. For example, the printing device DR1 prints the front side of the material to be printed web 3, and the printing device D2 prints the back side. The material to be printed web 3 is inverted by the turning unit 12 between the printing device DR1 and the printing device DR2. The rotation position transmitter roller 6 measures the feed motion of the material web 3 to be printed, and the measurement result is sent to the printer control device 2. The rotation position transmitter roller may be provided at the entrance of the first printing device DR1. The printer control device 2 receives a measurement signal from the rotation position transmitter roller 6 and controls the printing unit 1 and the drying unit as is known. The printed matter material web 3 printed by the second printing device DR2 is then supplied to the post-processing device 13.

When the pause function is investigated in such a twin printer without using the present invention, various factors of expansion and contraction of the material web 3 to be printed are found in the printing devices DR1 and DR2.

State in the first printing apparatus D1 The printhead 5 of the print unit 1.1 has an operating temperature of, for example, about 32 ° C. Due to the temperature difference that occurs with respect to the temperature of the printed matter material web 3, the printed matter material web 3 located directly under the print head shrinks. The shrinkage of the printed matter material web 3 and the accompanying vertical and horizontal displacement of the printed matter material web 3 cannot be recorded by the rotary position transmitter roller located at the inlet of the printed unit 1.1. Therefore, after the pause is completed, a print quality defect occurs in the first printing device DR1.

State in the second printing device DR2 The material web 3 to be printed, which has already been dried in the drying unit 10.1 after the printing process in the first printing device DR1, absorbs the moisture that causes the expansion of the material web 3 to be printed from the ambient air during the pose. The expansion of the material web 3 to be printed causes a change in the length of the material web 3 to be printed in the vertical and horizontal directions before and after the rotation position transmitter roller 6. The expansion of the material web 3 to be printed on the upstream side of the rotary position transmitter roller 6 and the displacement of the web in the vertical direction accompanying the expansion are recorded by the rotary position transmitter roller 6 and notified to the printer control device 2, and the printer control device 2 is notified. 2 modifies the control time point of the print head 5 of the print unit 1.2 accordingly. The expansion of the material web 3 to be printed on the downstream side of the rotary position transmitter roller 6 and the accompanying displacement (also the displacement of the material web 3 to be printed on the lower side of the print head of the printing unit 1.2) are the rotational position transmitter roller 6. Therefore, it is not possible to send a print pulse to the printhead in response to the displacement of the material web 3 to be printed. This causes distortion of the printed image. The shrinkage of the material to be printed web 3 is also performed under the print head 5 of the second printing unit 1.2. Of course, the shrinkage of the material web 3 to be printed counteracts the expansion of the material web 3 to be printed due to the moisture of the ambient air, and reduces the printed image defects caused thereby.

2. Solutions to the above problems in twin printing systems In the configuration according to the present invention, which avoids such an influence on the material web 3 to be printed and thus the printed image, different effects can be obtained in both printing devices DR1 and DR2 in the twin printing system.

2.1 Pose with pre-process time a) State in the second printing device DR2 Pre-pose process time t_vDuring operation at a reduced speed of the printed material web 3 during, the printed material web 3 is given more time to absorb moisture through the ambient air, so that the printed material web 3 is stopped. At the beginning of the pose with the state, most of the expansion of the material to be printed web 3 occurs. In order to support such an effect, if the printing apparatus DR is provided with appropriate means, another measure that affects the absorption of moisture by the material to be printed web 3 can be taken. -The provided cooling device allows the material to be printed web 3 to be additionally cooled. -The drying unit 10.1 of the material to be printed web 3 in the printing device DR1 can be turned off (blocked). -A fan can be placed in the turning portion 12 on the upstream side of the second printing device DR2.

b) State in the first printing device DR1 There, measures can be taken to reduce the heating of the material to be printed web 3 in the printing apparatus DR1. When the pause key is activated, the pause pre-process time t_vDuring, the temperature of the printhead of the print unit 1.1 can be reduced by about 2-3 ° C, so that the material web 3 to be printed shrinks only slightly underneath the printhead.

Additional measures can be taken for both printing devices DR1 and DR2, for example the printhead can be moved from the current printhead position during printing operation, eg 1 mm to 2 mm, at the start of the pose. This reduces heat transfer from the printhead 5 to the material web 3 to be printed.

2.2 Slow movement pose In the slow moving pose, when the pause key is activated, the material to be printed Web 3 slows down, for example v._s= It drops to 0.001m / s ~ 0.015m / s. In such a pause function aspect, the printed material web 3 does not stop. The slack of the material web 3 to be printed, which may occur on the downstream side of the printing device DR2, needs to be absorbed by the post-processing device 13 of the material web 3 to be printed.

FIG. 1 shows, for example, the printing unit 1 of the printing device DR, which is the printing unit of the printing device DR2 shown in FIG. 2, in principle. The printing device DR1 can be arranged on the upstream side of the drive roller 7 in the transport direction (arrow PF) of the material web 3 to be printed. Contact with ambient air occurs both upstream and downstream of the drive roller 7, and as a result, the material web 3 to be printed may expand. The degree of expansion is also related to the temperature of the material to be printed web 3 after being separated from the first printing device DR1. The expansion change of the material web 3 to be printed on the upstream side of the rotation position transmitter roller 6 is taken into consideration by the rotation position transmitter roller 6. The expansion change on the downstream side of the rotation position transmitter roller 6 may have a negative effect on the printed image. During the printing operation, for example, after printing a print job, when pauses are introduced to control register quality, the material web 3 to be printed expands or contracts upstream and downstream of the second printing unit 1.2. Therefore, when resuming printing, there is a risk that the printhead 5 of each print bar 4 will no longer form a print image on the material web 3 to be printed at an accurate point. To solve this problem, according to the present invention, the reduced feed rate v of the material web 3 to be printed_vPre-process time t_vIs introduced before the pose, or during the pose, the material to be printed Web 3 is speed v_sMove at low speed. As a result, the material to be printed web 3 can absorb moisture from the ambient air and therefore reaches the underside of each printing unit in the state during the printing operation.

From FIG. 3, the diagram of the velocity v of the material to be printed web 3 recorded with respect to the time t in the pause function of the printing device DR can be seen. -A in FIG. 3 shows the feed rate v of the printing material web 3 before, during, and after the end of the pause in the printing operation when the present invention is not used. The printing device DR first operates in the printing operation, and the material to be printed web 3 operates at the operating speed v._dTransported through the printing equipment DR, then the pause function is activated, and the printing equipment DR is short-lived, eg t_pStop (v) for 1 min_p= 0). After the pause, the printed material web 3 restarts and the printed material web 3 runs again at speed v._dIs accelerated to. -Fig. 3b shows the speed progress of the material to be printed web 3 during the operation of the printing device DR in the case of the pause function having the previous process. Driving speed v_dTherefore, the material to be printed Web 3 has a pre-process time t of, for example, 1 min to 3 min._vLow speed v over, for example 0.1 m / s_vIs braked. During this time, the material to be printed web 3 can occupy the humidity and temperature of the ambient air. The material to be printed Web 3 then has a pause time t, for example_pStop for = 1 min (v_p= 0). During this pause, for example, the problem in the post-processing 13 device can be solved. After the end of the pose, the material to be printed Web 3 runs again at speed v_dIs accelerated to.

Pre-process time t_vIs selected so that the material to be printed web 3 reaches the underside of the printing unit 1, and its properties correspond to those during the printing operation and are therefore already taken into account. For example, pre-process time t_vSelect the web segment BA1 (Figure 1) to reach the underside of the print unit 1 or pre-process time t_vCan be selected so that the material web 3 to be printed reaches the printing unit 1.2 of the second printing device DR2 at the exit of the first printing device DR1 or downstream of the drying unit 10.1.

From c in Fig. 3, the pause function with low-speed movement can be seen. Driving speed v_dFrom, after the pause function is activated, the printing speed of the material to be printed Web 3 is, for example, v._sIt drops to a low speed of 0.001m / s, for example t_pLow speed movement speed v during the pause of = 1min_sWill continue to be transported at. After the pause elapses, the material to be printed Web 3 will run again at speed v._dIs accelerated to.

DS printing system, DR printing equipment, 1 printing unit, 2 printer control device, 3 material to be printed web, 4 print bar, 5 print head, 6 rotation position transmitter roller, 7 drive roller, 8 guide support, 9 winding Roller, 10 drying unit, 11 storage roll of material web to be printed, 12 turning unit, 13 post-processing equipment, v speed, t time