Thermal Printhead Research Articles

Evaluation of the Structure of Phosphate Glass Samples Using TOF-SIMS

Phosphate glass represents a potential substrate material for use in thermal transfer printing heads, because of its lower melting point and environmental friendliness compared with lead-based glass. However, conventional phosphate glass does not meet the practical criterion for durability against water. We found that the addition of cerium dramatically enhanced the water durability of phosphate glass, and that this was further improved by the addition of Al2O3. The aim of this study was to understand the mechanism for this enhanced water durability through TOF-SIMS analysis. The incorporation of cerium into conventional phosphate glass resulted in an increase negative fragment ions with a higher mass, indicating the presence of a highly polymerized phosphate structure, probably the longer chain structure was stabilized by chelation between cerium and oxygen. The ratio of linear chain structure to cyclic ring structure (polymetaphosphate) also increased when cerium was added. The spectrum of the Al2O3-added phosphate glass indicated that aluminum had been incorporated into polyphosphate chains and that this converted the chains from two-dimensional to three-dimensional structures. The intensity of fragment ions related to P4O10 decreases with an increase in the water durability of the glass samples.

1312 昇華型熱転写プリンタ用サーマルヘッドの接触面における熱と応力の連成解析(OS01-3 + GS04 機械要素とトライボロジー + トライボロジー,オーガナイズドセッション 1:「機械要素とトライボロジー」)

1312 昇華型熱転写プリンタ用サーマルヘッドの接触面における熱と応力の連成解析(OS01-3 + GS04 機械要素とトライボロジー + トライボロジー,オーガナイズドセッション 1:「機械要素とトライボロジー」)

Study of Thick Film Thermal Head Structure

The protective layer for a thick--film thermal printhead is formed usually by the conventional screen-printing method. The curvature of the protection layer is dependent on the formation of the heater nib. If the cross-sectional structure of a heater nib is thin or wide, the curvature of the protection layer is large. Though the platen pressure becomes small, the printing characteristics is uneven due to larger contact area. On the other hand, if the crosssectional structure of a heater nib is thick or narrow, the curvature of the protection layer is small. The contact pressure with media is large and may generate sticking, and intense wear result. A new approach of protective layer formation by means of a direct dispensing system to realize a convex cross-sectional structure with a desirable curvature is studied. It possesses the following advantages over the conventional screen-printing method: (1) Forms of various curvatures can be studied, independent of the form of a heater nib structure. This is critical in manufacturing a high-resolution printhead where the heater nib is usually very thin, and high reliability and long life expectancy are desirable. (2) Reduction in manufacturing cost since screen masks are not required and the waste paste used in screen-printing is saved.

Characteristics of Carbon Nanotubes Based Micro-Bubble Generator for Thermal Jet Printing

We propose a conceptional thermal printhead with dual microbubble generators mounted parallel in each nozzle chamber, where multiwalled carbon nanotubes are adopted as heating elements with much higher energy efficiency than traditional approaches using noble metals or polysilicon. Tailing effect of droplet can be excluded by appropriate control of grouped bubble generations. Characteristics of the corresponding micro-fabricated microbubble generators were comprehensively studied before the formation of printhead. Electrical properties of the microheaters on glass substrate in air and performance of bubble generation underwater focusing on the relationships between input power, device resistance and bubble behavior were probed. Proof-of-concept bubble generations grouped to eliminate the tailing effect of droplet were performed indicating precise pattern with high resolution could be realized by this kind of printhead. Experimental results revealed guidance to the geometric design of the printhead as well as its fabrication margin and the electrical control of the microbubble generators.

Study of Performance Improvement for Dye-Sublimation Printer

Dye sublimation printer print is possible to print on the highresolution. But Dye sublimation printer receives high heat and pressure than Inkjet printer and Laser printer. Therefore, the surface paper is transformed, and there is a possibility of negatively affecting the print quality. Then, we verify the reason why the surface paper is transformed and Influence that transformation of surface paper gives print quality. (Key Words: Dye sublimation printer, Thermal print head, Micro heater, Numerical analysis, Positioning margi)

Development of Durable and High efficiency Thermal printhead

In recent years, applications with a thermal print system have been rapidly expanding to emerging countries. Under the circumstances, a lot of direct thermal paper is being developed locally by many companies leaving the end-users little to no choice but to use the local paper supplier.Unfortunately, some of this newly developed local direct thermal paper cause significant abrasions on the printheads forcing the users to replace the printheads frequently.Considering the situation, ROHM has developed a durable thermal printhead which can achieve three times longer life compared to conventional printheads, even with such severe locally manufactured medias. In addition, the new printhead has 15% improved energy-efficiency and contributes to the ability of accepting a low-sensitivity direct thermal paper.We have also developed AST (Anti Sticking Treatment) technology to prevent a sticking problem which causes a poor print-quality. The treatment also reduces paper residue build-up on the surface of printheads and keeps a good print-quality for continuous printing.

Development of Ultra High Resolution Thermal Printhead

Development of Ultra High Resolution Thermal Printhead

Modeling and Control of Thermal Printing

In this paper, we present the development of an optimal controller for thermal printheads. A first-order linear system and a nonlinear output mapping with stochastic noise is proposed as a model of the printing dynamics. The model parameters are identified and an optimal control problem is formulated to determine the printhead input. The control algorithm is successfully tested on a standard thermal printer. A sensitivity analysis is performed by simulations and experiments to analyze the printing quality on varying setups with different printheads, printing media and ribbons. A tuning strategy is derived to adapt to changing setups without having to recompute an optimization problem. The performance of the control system for a wide range of operating systems is observed in experiments. Comparing the proposed controller to a current control implementation shows a significant quality gain in barcode readability (ISO/IEC 15416).

Development of Power Saving Thermal Print Head Part 2

Power saving of Thermal Print Head was studied.Since heat characteristics and thickness of head substrate are effective on power saving, as reported in NIP25, low thermal diffusivity glass have been developed.FEM simulation was adopted to estimate the characteristics of Thermal Print Head efficiently.Phosphate composition which satisfies the requirement on Thermal Print Head such as homogeneity, 650 Deg C or higher Tg and climate resistance was found. Thermal diffusivity 0.33mm2/sec was achieved.Sample Thermal Head was made with substrate thickness calculated from simulation to satisfy both power saving and print quality.The test result of Thermal Head sample showed 25% power saving and sufficient print quality.

1414 広視野レーザ顕微鏡による昇華型熱転写プリンタ用サーマルヘッドの接触面観察(OS1-3 機械要素とトライボロジー3,オーガナイズドセッション:1)

1414 広視野レーザ顕微鏡による昇華型熱転写プリンタ用サーマルヘッドの接触面観察(OS1-3 機械要素とトライボロジー3,オーガナイズドセッション:1)

2113 広視野レーザ顕微鏡によるゴムとガラスの接触面観察(表面・接触,一般講演)

In a paper feeding system, a contact condition analysis between a rubber roller and a printing paper is needed for a stable feeding operation. Direct observation of the apparent contact area between the rubber roller and the thermal print head is also necessary for better understanding of the contact condition. However a contact microscope technique takes a lot of time to measure the real contact area. Thus another new technique is expected for faster observation of real contact area. In this paper, it was confirmed that a newly developed laser microscope with wide field of view was able to observe real contact area between the rubber plate and the glass plate. Then a distribution of real contact area of the rubber roller against the glass plate was also observed by this technique. In addition the micro-slips of the rubber roller were measured when the some torque was applied.

Development of High Efficiency Thermal Printhead

Recently, a large portion of product development is focused on environment protection. Especially, the reduction of carbon dioxide is targeted to prevent global warming. For the thermal printhead, the way to address this is to improve the heat efficiency in order to realize reduced energy consumption. Our newly developed printhead achieves significant improvement in heat efficiency. Two approaches are taken during this development; (1) control the heat flow in the heater, so that heat can be concentrated at the heater and (2) increasing glaze thickness in order to utilize heat accumulation more efficiently. Previously, to make better heat response with high speed printing, utilization of thinner glaze was adopted to prevent an “Obiki” phenomenon which is ‘trailing print’ on the media. However, this thinner glaze dissipates the heat quickly and as such can result in lower heat efficiency. This paper will describe how to use the heat accumulation by thicker glaze without significant print quality degradation by Obiki. In this way high heat efficiency is achieved.

Development of New Multi-Purpose Heating Head

We developed a new multi-purpose heating head. It resembles the traditional thermal printhead which has the resistive heating element on the ceramic substrate. Some differences are that it has a continuous resistive element while the printhead has an array of individual independent resistive element heating dots. Consequently, the methods to energize two devices are different. The most significant difference is that it has the heating element on the back side of the ceramic substrate and the media contact is on the front side of the substrate. This unique structure solves many problems which have been difficult and costly to deal with in the traditional structure. Heating element abrasion is no longer a problem as the media is not in contact with the heating element side. The heating element protective over-coating layer is not needed. Other benefits are the even temperature distribution throughout the heating head and easiness of manipulating the heating characteristics of the heating element. A family of heating heads using this idea has been made from small to large format. The new concept product is suitable for thermal rewritable printer erase head, thermal re-transfer printer heating head, pre/post-printing process of printing media and electrophotographic printer toner fuser.

Development of ultra high density thermal printhead

Recently, resolutions of printing devices are increased rapidly. Obviously, higher density makes better quality for any type of print. In regard thermal printing technology, highest density of mass production printhead is 600dpi except for the particular application of higher density than 600dpi with small quantity. To search the possibility of much higher density by thermal printing method, Kyocera developed 2400dpi and 4800dpi thermal printhead, and made printouts successfully. Printouts by those ultra high density thermal printhead are too small to see by naked eyes. Microscope is required to see it. The other hand, there are issues to solve as thermal printing with this ultra high density. In this paper, future possibility and issues of ultra high resolution thermal printing are introduced. Also the new potential application will be discussed.

Development of Power Saving Thermal Print Head

We examined a power saving on thermal printing.Development of Power saving thermal print head by 3D thermal analysis.Thermal printer is a simple structure, and it is small suitable. Therefore, it is widely used for a direct, thermal printer and a mobile printer of the built-in type. The power saving of a thermal head have to achieve for the battery longevity in a mobile printer and the speed-up of the Thermal printing.We looked into thermal head structure, energizing condition and medium structure suitable for power saving. The numerical analysis by the finite element method was applied to the examination.It reports on the content that optimizes the structure to make the printing quality united to the power saving.

Development of Dual-Line Wide-Format 1200 dpi Thermal Printhead

The wide-format dual-line 1200 dpi thick film thermal head was developed utilizing the following technologies: (a) an alternated conductive lead circuitry inside the thermal head is devised in that it does not use diodes for the prevention of reverse current; instead, it adds a secondary power supply to redirect the reverse current. (b) The heater nib line of the printhead is produced stably and accurately using the direct dispensing system which, based on the air microtechnology, feeds back the air pressure and controls the linear actuator to follow the surface of a substrate. (c) The 1200 dpi printhead is combined of two identical 600 dpi nib lines with half-pitch offset in the nib line direction and separated by a distance of 32 nib lines in the printing direction. Although the printhead is not made of a 1200 dpi single nib line and may be classified as a quasi-1200 dpi printhead in a more strict sense; however, it does exhibit a 1200 dpi-like performance and, for the convenience of presentation, it is still called a 1200 dpi printhead in this article. Several wide-format (up to 54 in. width) products based on the 1200 dpi thermal printhead have been designed and are capable of printing half-tone images of up to 133 lines per inch.

Analysis of Contact Pressure Acting on a Thermal Print Head of a Dye Sublimation Printer

The printing method of the dye sublimation printer is to push and heat a dye-based ribbon by a thermal print head, and diffuse the ink dyes to desired positions into the receiving layer of a paper. In a previous work, a real contact area between the ink dyes and the paper was necessary to increase the optical density. The ink dyes were effectively heated at the real contact area, to diffuse the ink dyes into the receiving layer. Thus it is important to place the heater of the thermal print head at a position where the contact pressure is most high. The contact pressure distribution acting on the thermal print head was calculated by FEM. The friction force on the thermal print head shifted the contact region to the paper feeding direction. On the other hand, the viscoelastic property of the platen rubber shifted the contact region in the opposite paper feeding direction. The friction force on the thermal print head influenced the contact pressure distribution than the viscoelastic property of the platen rubber. Then, it didn't need to consider the viscoelastic property of the platen rubber to calculate the contact pressure distribution. To examine the effect of the contact pressure on the print quality, the optical densities were measured with the heater positions on the thermal print head changed. It was found that the optical densities increased along with the increasing contact pressure.

Slipping Stability Improvement in Thermal Dye Transfer Printing System

Thermal dye transfer printing method has often been adopted in the field where high-quality image is required for the on-the-spot output due to the advantages such as in gradation expression, output speed, and system stability. In this method, further system stability and maintenance-free operation are required in the deployment of minilabs where larger volume of prints with higher speed is essential from now on. To realize these requirements, with an objective to improve slipping stability in the thermal dye transfer printing system, a new heat-resistant slipping layer of the ink ribbon has been designed. This report discusses improvement of friction stability between thermal printhead and heat-resistant slipping layer, and substantial decrease of abrasion-resistance against thermal printhead protective layer.

Greener Ink Technology for Wide and Super-Wide Format Inkjet Printing

Hewlett Packard has recently introduced a novel water-based outdoor durable ink and printer solution for the wide and super-wide markets: the HP Designjet L65500. Printed images exhibit good lightfastness (with and without lamination), and durability similar to conventional solvent-based inks. The heated printing system enables imaging on a broad range of media designed for solvent ink printers, including inexpensive uncoated vinyl. Low cost, easily replaceable thermal inkjet print heads provide excellent service life and high reliability. The ink is water-based, low VOC, and HAPS-free, and as a result, no special ventilation systems are required. Image durability is provided by a novel synthetic polymer dispersion. The ink formulation and printer design considerations enabling this breakthrough technology will be discussed, including ink durability, printer dryer design, and print head reliability.

Development of dual-line wide-format 1200-dpi thermal print head

The wide-format dual-line 1200-dpi thick-film thermal head was developed utilizing the following technologies:□ An alternated conductive lead circuitry inside the thermal head is devised. The circuitry does not use diodes for prevention of reverse current; instead, it adds a secondary power supply to redirect the reverse current.□ The 1200-dpi printhead is combined of two identical 600dpi nib lines with half-pitch offset in the nib line direction and separated by a distance of 32 nib lines in the printing direction.□ The printhead is manufactured by the direct dispensing system using the air micro technology which feeds back the pressure and controls the linear actuator to follow the surface of a substrate so that a heater nib line can be produced stably and accurately.□ Several wide-format (up to 54” width) products based on the 1200-dpi thermal print head have been designed and are capable of printing half-toned images of up to 133 lpi (line per inch).