Research on nozzle cleaning technology of inkjet printers

The ink at the opening may solidify, causing the nozzles to clog or smearing the print media during printing, seriously affecting the print quality.In order to prevent the nozzle from clogging or smearing the printing media, the nozzle surface needs to be cleaned in time.
There are generally three methods to clean the printing nozzle: one is to drive fluid through the outside of the nozzle; the other is to use a wiping structure; the third is to use cleaning fluid.Among them, using a wiping structure to clean the printing nozzle surface is currently the most commonly used cleaning method.How to use the wiping structure to achieve a better cleaning effect on the surface of the printing nozzle has become an urgent problem in the industry.
This article focuses on the field of using wiping structures to clean printing nozzles, and analyzes the current patent development status from the dimensions of patent application trends, technology sources, technology distribution, and main innovation entities.
Analysis of technological development status
1. Patent application trend analysis
Figure 1 shows the global patent application trend in the field of using wiping structures to clean the printing nozzle surface.Analysis shows that in the past 20 years, the number of global patent applications in this field has fluctuated.Before 2016, the number of patent applications per year was mostly between 200 and 300, with little change. It can be considered that the industry is in the growth period, with slow progress in technology research and development and relatively small output of innovative results.Since 2017, the number of patent applications in this field has increased significantly, with the annual number of applications exceeding 300, reaching a recent peak of 413 in 2019. It can be seen that technological research and patent protection in this field have entered a stage of rapid improvement, and the scale of the patent layout of innovative entities continues to expand.The number of patent applications has dropped significantly in the past two years because it takes a certain amount of time from submission to publication. Therefore, some patent applications have not yet entered the public stage and cannot be counted, so they are for reference only.

2. Analysis of patented technology sources
Figure 2 shows the distribution of patent technology sources in this field.The analysis shows that more than 50% of global patent applications in this field originate from Japan, with the number of applications reaching 3,511, ranking first. It can be seen that Japanese innovation entities have an absolute advantage in technological research in this field; followed by the United States, accounting for 16.8% of patent applications. %, ranking second, indicating that American innovation entities have also conducted in-depth research in this field, and the scale of patent layout is second only to Japan; in addition, Ireland’s patents accounted for 8.4%, ranking third, and its innovation strength cannot be underestimated. ; South Korea and Australia's patents account for slightly more than 5%, and there is not much difference in innovation strength; while China's patents account for only 3.4%, indicating that my country's innovation entities have relatively little technical research in this field, and their innovation strength needs to be improved.

3. Analysis of main innovation entities
Figure 3 shows the ranking of major global innovation entities in this field.The analysis shows that among the top ten innovative entities, 6 are Japanese companies, which shows that Japanese innovative entities have considerable strength in this field.In addition to the absolute advantages of Japanese companies in this field, the United States' Hewlett-Packard Company also has strong competitiveness. Its R&D investment and number of patent applications rank third in the world.In addition, Ireland's Mamjet Technology also has certain R&D capabilities, ranking fourth.Although China ranks sixth in the world in the number of patent applications in this field, as the applicants are mainly scattered among small and medium-sized companies, no Chinese innovation entity has ranked among the top ten in the world.

Figure 4 shows the patent application trends of major global innovation entities.The analysis shows that in the past 20 years, Seiko Epson’s patent applications have generally shown a growth trend, especially after 2013, the number of applications increased rapidly. Although there was a slight decrease from 2017 to 2019, its number of applications is still far higher than that of other competitors. It can be seen that In recent years, its innovation trend in this field has been active, and its technology has developed rapidly.Canon and HP's patent applications also show a steady growth trend in general, with the annual number of applications being less than 50.The patent application trend of Mamjit Technology fluctuates greatly. Its application volume grew rapidly before 2011, and surpassed Seiko Epson, Canon and HP in most years. However, it began to decline rapidly after reaching the peak in 2011, and its development potential insufficient.The number of patent applications of Brother Industries remains relatively stable, with the number of applications in most years ranging from 10 to 20.

4. Analysis of important technical branches
Technical branches with a larger number of patents are generally considered to be more important technical branches, and technological innovation is relatively active.According to the CPC classification number, the technical field of cleaning printing nozzles using wiping structures is divided into 4 important technical branches, namely: B41J2/16538 (cleaning nozzles with brushes or wipers); B41J2/16541 (cleaning nozzles from wipers or scrapers) Device for removing deposits); B41J2/16544 (positioning structure of wiper); B41J2002/1655 (cleaning belt cleaning nozzle).
Figure 5 shows the trends in patent applications for important technical branches in this field.The analysis shows that the innovation entities in this field have been relatively active in innovation in the three branches of B41J2/16538, B41J2/16544, and B41J2002/1655 in the past ten years, and the number of patent applications has maintained substantial growth amid fluctuations. In 2017, the number of applications in these three branches The number of patent applications in the B41J2/16541 branch has remained stable for a long time, which shows that the innovation vitality of innovative entities in this branch is relatively weak.

Figure 6 shows the distribution of patented technologies in the world’s major filing countries.The analysis shows that B41J2/16538 (brush or wiper scraper cleaning nozzle) is the most concerned technology branch in this field, and the number of patent applications in this branch is relatively large in each major applicant country.Japan and the United States rank among the top two in terms of the number of patent applications in the four major branches of this field, far exceeding other countries and leading the overall innovation activity. However, other countries have less than 100 applications in the above four branches, and their technical strength is relatively low. Weaker.

Figure 7 shows the distribution of patented technologies by major global innovation entities.The analysis shows that the top five innovative entities in this field, such as Seiko Epson, Canon, HP, Mamjet Technology, and Brother Industries, have patent layouts in various technical branches, and their research and development covers a wide range of areas.B41J2/16538 is still the technology branch that industry giants are most keen on researching, and the number of patent applications is significantly higher than other branches, indicating that the research and development focus of major global innovation entities in this field is mainly focused on using brushes or wiper scrapers to clean nozzles.

Analysis of key patent technologies
1. Brush or wiper blade cleaning nozzle
Technical research on wiper blade cleaning nozzles mainly focuses on improvements in wiper structure and installation methods.As shown in Figure 8, the wiper disclosed in Hewlett-Packard's patent application (CN102858545A) includes: a first wiper section whose width is approximately equal to the width of the orifice area of ​​the small printhead assembly; adjacent to the first wiper section a segmented separator; a second wiper segment adjacent to the separator such that the wiping action of the first wiper segment is not affected by the second wiper segment, the first and second wiping The combined width of the wiper section and separator is roughly equal to the width of the orifice area of ​​the large printhead assembly. Setting the same wiper into two sections can wipe nozzle surfaces of different sizes at the same time.The wiper is tilted on the mounting base. For a wiper without an angle, when the wiper blade cleans the print head assembly, all the energy stored in the curved wiper blade will be released immediately.In contrast, for angled wipers, such as those where the wiper gradually engages and disengages from the printhead assembly, it spreads the energy release over time, thereby reducing its amplitude and improving the acoustic quality that accompanies the wiping process.

2. A device for removing deposits from a wiper or scraper
The wiper will be contaminated by the ink on the nozzle surface during the wiping process, which will affect the next wiping, so it needs to be cleaned.As shown in Figure 9, the device for removing deposits from a wiper is disclosed in the patent application (CN108943720A) of Sanwei International Three-dimensional Printing Technology Company. When cleaning the coloring nozzle 20, the movable scraper 200 rotates to move the contact end 220 out of the cleaning area. The opening 101 of the groove 100 interferes with the water-absorbing interference piece 300 during the movement. The water-absorbing interference piece 300 absorbs the cleaning liquid 10 attached to the contact end 220, thereby preventing the contact end 220 from being stained with too much cleaning liquid 10 when scraping the coloring nozzle 20. Attached to the coloring nozzle 20, thereby preventing the cleaning liquid 10 adhering to the coloring nozzle 20 from adhering to the material powder and forming sludge.The coloring nozzle 20 contacts the contact end 220 and moves horizontally to make the contact end 220 scrape off the sludge attached to the coloring nozzle 20. After the cleaning is completed, the movable scraper 200 rotates to move the contact end 220 into the cleaning tank 100. At this time The water absorption interference piece 300 moves out of the movement stroke of the contact end 220 to avoid adsorbing the sludge attached to the contact end 220 .The contact end 220 of the movable scraper 200 is immersed in the cleaning liquid 10, and the cleaning liquid 10 dissolves the sludge attached to the contact end 220, and the contact end 220 further moves to contact the submersible interference piece 400, and the submersible interference piece 400 is scraped away The sludge attached to the contact end 220 is thereby cleaned to clean the movable scraper 200 for the next cleaning of the coloring nozzle 20 .

3. Positioning structure of wiper
When the wiper wipes the nozzle, it requires a driving device to position the wiper to the nozzle surface.As shown in Figure 10, in the wiper positioning structure disclosed in the patent application of Mingqi Dentsu Co., Ltd. (CN1332085A), a cleaning sled is provided in the housing of the maintenance seat, and the cleaning sled can slide forward and backward.After the nozzle enters the maintenance area, the relative movement of the cleaning skid and the housing will force the wiper holder to slide from the wiper holder dock into the work area.A simple locking mechanism secures the cleaning sled and maintains the wiper holder in place.When the inkjet print head leaves the maintenance seat, the nozzle will be cleaned, and after cleaning is completed, the print head will release the locking device and the cleaning sled will return to its original position, thereby moving the wiper holder back into the wiper holder dock. No longer linked to the print head nozzle.

4. Cleaning belt cleaning nozzle
When cleaning the nozzle with a cleaning belt, better cleaning results can generally be achieved by using a cleaning fluid in combination.As shown in Figure 11, in the wiper disclosed in the patent application of Fujifilm Co., Ltd. (WO2016047420A1), the delivery-side mesh core 102 is a cylindrical member that extends horizontally and is rotatably supported around an axis. The nozzle wiping sheet 120 is wound around the outer peripheral surface of the side mesh core 102 .On the other hand, the winding-side web core 104 is a cylindrical member that extends horizontally and is supported rotatably about an axis, and 120 rolls of nozzle wiping sheets 120 are fed out from the delivery-side web core 102 and wipe the nozzle surface 57K. Wrap into roll shape.The nozzle wiping sheet 120 sent out from the sending-side mesh core 102 is pressed against the nozzle surface 57K of the inkjet head 56K by the pressing roller 110, and wipes the ink and other droplets adhering to the nozzle surface 57K.Then, the nozzle wiping sheet 120 that has wiped the liquid droplets reaches the winding-side mesh core 104 and is wound, so that the nozzle surface 57K is wiped efficiently by the nozzle wiping sheet 120 .Since the cleaning liquid 108 is supplied by the cleaning liquid applying mechanism 93, a more effective wiping effect can be achieved.
This article analyzes the current status of patents in the technical field of cleaning printing nozzles using wiping structures, which can provide reference for innovative entities’ technology research and development, innovation breakthroughs, and patent layout strategies.It can be seen from the analysis of data statistics and technological development status that the number of global patent applications in this field has generally shown a fluctuating development trend in the past 20 years. Before 2016, it was the growth period of the industry, and the number of patent applications each year was relatively small; since 2017, the number of patent applications in this field has generally fluctuated. Field technology research and patent protection have entered a stage of rapid improvement, and the number of patent applications has increased significantly.In addition, Japanese patent applications in this field account for half of the country, and 6 of the top ten innovative entities in the world are from Japan, giving them an absolute leading advantage in R&D strength.

At present, the development of the main technical branches in this field is relatively mature. During the development process, there have been many application peaks accompanied by breakthroughs in core technologies, which shows that the technological development in this field is sustainable and has strong vitality, especially in recent years, global patent applications in this field There is an obvious upward trend, and it is foreseeable that new core technologies will be born in the future, and the number of patent applications will reach another peak.