Out. Bring It. Right The First Time. LEGEND PRINTING What Goes On The Outside Is Reflective Of What s Inside

Transcription

1 Bring It Out Right We make the input devices that control the OEM products that operate the world. LEGEND PRINTING What Goes On The Outside Is Reflective Of What s Inside Learn how Legend Printing techniques are making greater impressions on the user experience. In this month s Tech Viewpoint, reviews the merits of the technologies chosen, potential design impediments, and long-standing questions regarding material types: membrane switch assemblies (thin plastic sheets), rubber (or elastomerics), injection molded plastic, and metals. What is the importance of legend information in the sale or development of a project? Trace the differentiators and consider their implications before creating your next input device design.

2 WE MAKE THE What goes on the outside is reflective of what s inside What is the importance of legend information in the sale or development of a project? It is often a minor detail in a series of events that make up the final product almost insignificant at first glance. But in the world that we live in, is it? You most certainly will not see all the special features of the product you buy as a consumer the internal workings, the quality of the hidden construction or the special features under the hood so to speak. In fact technology is increasing and developing to the point that most of us have very little understanding of what is inside anymore anyway. The cosmetic features that decorate the outside, along with the company s logo, are all you can see and they will stand out for the life of the product. Logos and legend information, especially in this case, are becoming more important daily to the consumer as the technology gap increases. Most firms spend a great deal of money on the cosmetic touches developing and creating their company legend to reach you the consumer. The intent is to have it representative of the item you buy, to be prominent in a not overbearing way, to make a statement about your choices, to establish trust and to send a non-verbal message to you within the confines of its borders. What do you think of when you see the Nike swoosh, the Rolex crown, Calvin Klein on clothes, the cameo of the See s grandmother, the Maytag emblem or the Mercedes silver star over the hood? So we do, admittedly, often judge a book by its cover. You could also think of it another way. That significant person in your life knows you are a good person within but still, for special occasions, you dress the part and take care of the small details of looking good on the outside to be as presentable as possible to them for these special occasions. In both examples the outward information was important. In the same way the graphics, logos or key legends that become a final part of the keyboard product is of vital importance to the company producing the product and to us here at. It is proof of quality on the inside. In this technical bulletin we will look at the various types of legend information, how they are related to material types and factors that you should be aware of in creating your next customer s design. Legend Types Best Defined Based Upon the Base Material In presenting this information it seems the base material that the legend information goes on is the best way to categorize the ways in which we identify keys. The four basic types of materials that we print legend information on are membrane switch assemblies (thin plastic sheets), rubber (or elastomerics), injection molded plastic and finally metals. Membrane assemblies: In thinking of membrane keypad legends it is best to think backwards. The top polycarbonate or polyester layer of the membrane itself usually acts as the legend protectant. The numbers, symbols or alphabetical characters are put on from the back, facing upwards, with outer and background colors layered on behind the characters in a specific sequence. This is done through a silk-screening process. Generally speaking the only layer that goes over the top is the UV protectant a textured overcoat that breaks up the reflectivity of light shining on the outer surface. Depending on the types of colors that are required for the characters a common background layering might consist of the following: UV velvet overcoat, several colors for legend information, custom background colors, a possible dead front requirement, a barrier black back coating and finally a masking layer for adhesion to additional layers beneath. All in all a very intricate process requiring multiple silkscreening sequences and exact layer to layer coordination to inter-relate with key locations, hidden components and embossing criteria. Pictured: membrane assembly A membrane assembly with white and black legend colors, various symbols and background colors along with perimeter embossing rings to make the buttons stand out. The whole process takes skill and experience. 2

3 Legend Types (cont d) Embossing is the last way to highlight a legend by raising it slightly from the background, giving it a raised perimeter in addition to raising the key to make it more distinctive or employing a more intricate multiple step embossing process for various effects. WE MAKE THE Elastomers: The methods of putting characters or backgrounds on elastomers can be done by silk-screening, through special molding requirements and by painting / laser etching. These following methods are defined as follows: A. Silk-screening: Referenced previously in Membrane Assembly, this is a method whereby legend information is transferred to the product by pushing colors through a screen. The screen has been pre-conditioned to allow the passage of the color only in certain areas and also acts as a regulator to allow passage of the ink at a certain rate. Pictured: Several different concepts that go into just one elastomer piece. Various flow molded backgrounds are shown for the Stop button, Start button and the background carrier. In addition the two arrow-up keys to the lower right are over-molded on to the background carrier piece as a second operation in the process. Legend information and green backgrounds were transferred to the part surface by silk-screening. Pictured: Front and back view of an elastomer keyboard. What is shows from the back is the clear white translucent material that the LED s shine through. From the front side you can see that the carrier material has been painted over with two colors (white with black over the top of it) and then a laser machine etches away the black paint in the areas that the legends are required. The result is clear white legends inside of a black background with LED backlighting. B. Insert molding or flow molding: This refers to the same process whereby additional cavities are made in the compression mold so that the elastomerics can be formed together into a final two or three part process or flow molded in one complete step. Usually this applies to the background of a key or the top of a key that requires a separate color from the background carrier color but could also apply to molding a character out of a separate material and molding around it to achieve varying properties of color or transparency in a specific area. C. Painting / laser etching: This defines the process where by the base key is molded a certain color, or painted a specific color, and a final color is put over it all. This final color is then laser etched through in the areas of the specific characters to reveal the colors underneath. The final product has the quality of showing the legends plainly in daytime and backlighting the legend information in the dark. Plastics: Similar to elastomers, plastics are printed in the same methods as mentioned; silkscreening, tampo printing, laser etching and insert molding. Two unique faucets not mentioned before that relate specifically to plastics are laser marking and the legend transfer process (LTP), otherwise known as diffusion bonding. Pictured: Two translucent, painted plastic parts. Painted for the purpose of controlling the light transmission in the outer knob and centering backlighting to the legend on the center piece. The same part is shown from the top and on edge for clarity. 3

4 WE MAKE THE Legend Types (cont d) A. Tampo printing: A method whereby legend information is transferred from an ink bearing cliché surface bearing the legend information through tampo pads to a keyboard surface. Characters and backgrounds can be all one color or vary in color from knob to knob using a common cliché. B. Laser marking: The same laser equipment is used in this process however there is no paint to remove. Instead the laser acts like a hot marking tool actually changing the molecular attributes of the surface being heated so that the legend character information gets burned into the surface of the keytop. The upside is the degree of legend wear the character is imbedded into the plastic substrate for virtually the life of the key. The downside has to do with choosing the correct type of plastics that can be used and color variance the legend is usually dark grey or brown in nature and is best shown on a light white or grey background. C. Legend transfer process or diffusion bonding: The legend transfer process deals with pre-printed legend character information on special paper. The paper is aligned over the keyboard via coordinated tooling and a hot die transfers the character information from the paper into the substrate of the plastic by turning the legend into a gas that diffuses into the substrate of the plastic. Various colors can be printed on various points of the key; the limiting factor is certain type of lighter legend colors and using the correct type of plastic (polyester blends) that can handle the high heat involved in diffusing the legend into the plastic. Pictured: Plastic assembly having several types of legend information rolled into one unit. The QWERTY keyboard is laser etched, various legends are laser marked into the bezel (note active mode and 2D ) and the keys are laser etched to reveal the white legend for backlighting by LED s. Metal: Similar to both elastomers and plastics metals can be printed using most of the following means already stated above; tampo printing, laser etching and laser marking. Metal keys are often used in vandal proof products where the keycap, as well as the legend, needs to have exceptional durability. Pictured: Ruggedized keyboard for vandal proof applications in open market places or public areas where equipment is left unsupervised. Such an application calls for a keyboard that has durable metal keys, sealing capabilities that meet the environmental conditions at hand and excellent legend wear characteristics. The legends in this case were laser etched through the outer coating of the aluminum key to white layer below. This is permanent marking at its best. Characteristics in Developing Correct Legend Qualities Keep in mind the following issues and vender support when reviewing legends and character development on projects: A. In house graphic capabilities: In dealing with the development or transfer of graphic information it is important to have a graphics department at least at the receiving end to sort out the needs of the customer, make suggestions and final finish of the product. 4 B. Color: Working with industry standard color references (Pantone / Munsell) and working with the final design testing criteria to match colors to specific end requirements are necessary to correct color matching. This also applies to working with customer samples, where the color needs to be pulled from the part provided, and matching to peripherals where your part will have to match the background surface that it is applied to. C. Wear: Probably the most serious characteristic affecting the product this is the issue that determines long term customer satisfaction. Extra care needs to be given to provide not only the correct type of legend process but determine needed wear characteristics based upon the environment that it will be used in. This is so that the legibility characteristics can be kept in near original condition for the expected life of the project.

5 Characteristics in Developing Correct Legend Qualities (cont d) D. Transparency: For backlighting purposes, legends are made transparent by processes that vary according to the material involved. E. Environmental considerations: A factor in selecting the correct type of marking process, this must be derived from customer conversations and engineering requirements specifically stated in the project. WE MAKE THE F. Matte finish: A factor not only in protecting the legend already put on the surface but in also determining how that same legend is viewed from a glossy surface to a knock down type of non-reflective matte finish. Making Legends Every Day We would like to help in meeting your design needs for all areas of graphics, legend development and keyboard integration. As a leader in custom keyboard applications, Advanced Input Systems can meet your needs using our extensive engineering resources and proven innovative solutions. Please visit our web site at or call directly at KYBD (5923) to get more information. Create or enhance your unique product requirements with an experienced team leader Esterline Corporation. All rights reserved. Trademarks and trade names are property of their respective owners. reserves the right to make changes to products and services described herein without prior notice. 5