Let me give you alittle background. DuPont, as you know, is a fairly diverse corporation. In particular, our strengths are in polymer chemistry.What you might not know is that we also have core strengths in what is called photopolymer technology and, actually, there's a lot ofoverlap between these two. We make a large number of products that are used in the printing and graphics industry. I am in what's called theDuPont Printing and Publishing business unit. I'm currently a senior scientist with DuPont and have been with the corporation for 20 years.I've had the advantage of being able to work in a number of different businesses involved w ith basic research and product development in polymer chemistry, photopolymer chemistry and currently I'm in thePrinting and Publishing division where I am associated with a venture in ink jet printing. Thus you can see, we have quite a range of technologies that can be utilized. What I'd like to do today is give you an overview, essentially, to stimulate some discussion on the "art of the possible"; the use of polymer chemistry and photopolymer technologies to produce tactile graphics. I'd like, before I get into talking about some of the particular items, to just mention that there are a number of items that I could talk about within the corporation, but unfortunately, I cannot discuss them in this forum because of the proprietary nature of these items. There are a lot of things that we could bring to bear on the formation of tactile graphics so if anyone has any specific questions, they can contact me after the conference and I will set them up with a specific contact within DuPont. The presentation today will only discuss some technologies that have been disclosed to the general public in publications, patents and research disclosures. What I have done is to identify a number of different technologies that could be applied or have been applied for making tactile graphics or braille images. I split these up in this presentation into three categories. The first one we're going to be talking about is Active Media. Here a physical change or chemical change occurs in the media, support or paper. The second one is Printing Methods, just a working title here but, essentially, this involves putting materials directly on a support, paper or some kind of media. And finally, there's some new technologies, particularly one of them, that might be used to manufacture molds for making multiple copies. So, I'll be addressing all three of these categories. During this presentation I will also classify the various methods into three types of output. The first type is single copy output. Here an example would be a computer printout from your desktop computer. The second classification is multiple copy output. An example of this method would be standard off-set printing. The third general classification would be reusable media, such as a tablet ; something that could be reused or hooked up to a computer and would continuously provide varying output. The first general classification of technologies to provide high resolution tactile graphics is Active Media. Under active media and single copy output, I'd like to do briefly review three items that have been described in patents and patent applications. For thermally expandable plastic sheets or paper, there are a number of different publications that have described various methods of incorporating materials into the support that when it is imaged or somehow excited with a thermal source, an example might be an infrared laser, you can generate raised images which are permanent. I might say as we're going through this presentation, that I have prepared a five page printout with representative references for each of the examples. If you would like me to send you a copy, you can contact me at the numbers given on the first chart. Again, our first example in the Active Media category would be technology that uses some type of material that is embedded or somehow coated on a plastic sheet or a paper that would typically be imaged by an infrared laser. These lasers are common and fairly inexpensive so that the process should be fairly straight forward.However, who knows what the quality of the images would be? But this is one approach that has been explored. The second example I have on the chart is ultraviolet hardening of a photopolymer film. By photopolymer, I mean organic based films that you can observe, when maged, a physical change. You then use these physical changes in various types of readout methods. Her e there are a number of cases, and we have seen some in our own work. If you image a plastic film containing a coating of a photopolymer, the areas that are exposed will rise and you can get quite a perceptible change in height between the background, which is unexposed, and the exposed image. So this would be another way of generating images. You could do this imaging process with an exposure mask. You could then repeat the process with a second piece of film to get multiple copies from the same image. Or, you could do a similar process in-line with a laser scanning exposure device, for example a diode laser. Now, the third category under single copy output I have is a technology that involves swelling the recording surface. And here the idea, as reported, essentially provides a media that can irreversibly swell when you apply a certain liquid. This liquid would be imbibed into the surface of the media anywhere the liquid is applied; then you would get swelling and a raised image. A general way of applying this liquid, of course, would-be ink jet, which we'll talk about next. So here are three possible ways, and there are more, that you could conceivably utilize media to make a raised tactile images. In the next slide, we will talk about reusable output in Active Media. There are a few technologies that have been described where you have a flat planer media and underneath that media, you have a matrix of some sort of elements. In the most common case it would be, of course, mechanical devices. By adjusting the height of a mechanical device, you can sense the pattern being formed. There are some cases where this is done by controlling the temperature of individual heating units some sort of an element that, when heated, would expand and the surface would change in dimension. That is one possibility, but the resolution might be rather limited. This would be an ideal output source to hook up to your personal computer or some sort of computing device where you have the memory that can address each of those individual elements to provide a fairly good sized platform on which you can read-out your image.
These are just some of our thoughts on Active Media. Some are certainly more advanced than others and there are others, as I mentioned, that would have some possibilities. Let's now talk about Printing Methods where we have a flat, or almost flat surface, and we're applying materials to the surface to make our raised images. The most obvious example that we all think about are the various ink-jet processes. We know in-jet is getting quite a bit of press recently. We're seeing a lot of high resolution devices being introduced. Certainly Hewlett-Packard and Canon are very active in this area and there are a lot of other manufacturers who are making products for other than the office environment; although this is the biggest market segment. There are a number of ways you could use the ink-jet process to print media with ink. For those that you who might not be familiar with the ink-jet process, it involves the accurate flow, or spitting out, of very small amounts of liquid onto a surface and by moving the jet head, you can write various patterns. The first process I would like to discuss uses a thermal or light curable ink. There have been actually a few reports using inks that have some mass to them so that when they come out of the ink jet heads they will actually form raised patterns with fairly high resolution. We also have meltable waxes that can be used,and I see there's several presentations later on in today's schedule on wax-jet printers; a very viable technology. The general object of these processes is to have an ink that you can spit out of the printhead and then cure the ink to lead to a hard, durable, image. There're are also some reports of using inks that contain materials that willactually expand, or generate foam, when they are printed by an ink-jet process. The process would be to print the image with this particular material, treat the printed image with the heat or may be light and, in the process of heating, the inks would expand. You would get a much greater height contrast with this process. There are alsoa number of reports of technologies that combine ink and media. By media, I mean paper or a printing receptor. A combination of using specific inks with a media which would expand thermally only in those areas that received ink is a possibility and this has been described in one of the references I have listed. Another process that is quite possible, and actually we use something like this in a commercia lproduct, is that you have a tacky ink, or an ink that will retain some tack when it's put down on a paper. Then on top of the ink image you can apply a powder by some means and, essentially, you can define a nice raised pattern. Subsequent thermal curing or light curing will give you a durable image. All of these ink-jet process have the potential advantage of being able to simultaneously print both the tactile image and a conventional printed image, if you use twodifferent types of print heads; one for putting down normal ink-jet inks and the other one for putting down your tactile image. So, it ispossible to get printed media with both conventional printed text and your braille or raised images. In the next slide, I talk about Printing Methods that provide multiple copy outputs. The examples on the previous slide all generated single copies for the most part.Under multiple copy output there are a lot of different processes and they are essentially related to printing. I'm sure you are familiar with the general methods of printing, in particular printing a tactile image. Screen printing would be a possibility where you form your image on some sort of carrier. In this process, an image is normally placed on a silk screen, the screen is placed in contact with the media, ink is forced through the back side of the screen and printed on the desired media. You can then cure the ink, usually by heating,to give a hard image. The second process under multiple copy output is just a conventional printing process where you make a printing plate and use a special ink that would have the property of giving a raised image. This is described in a number of patents or patent proposals in the last few years. All these are directed towards making a large number of copies of the same text. One method of duplication that might be useful in an office environment, where you need multiple copies, would be the normal copying process; electrical photographic printing or xerography type processes. A number of people have described uses of special toners and paper that will give you a raised image.
Most of these images will be somewhat soft and could bedamaged, but they do have the possibility of using conventiona lequipment with special toners to make raised patterns. The first twogeneral topics we've talked about are reactive media or active media where we use the support or paper to develop the raised pattern. The second approach was to apply a material, that we might call an ink, to some sort planer material to form the pattern. To get into the production of a large number of copies, it is quite common, as youknow, to make a mold. What I have in the last chart, under Productionof Molds, are the descriptions of two newer technologies that can beused for digital manufacturing of these molds. The first process ispretty much a brute force method in the sense that you have a sheet of material and you mill off what you don't need to make your raised pattern. There are a number of systems being introduced now where you are able to take your three dimensional design and generate a raised tactile image in a three dimensional form on a computer screen by computer aided design graphics. Three dimensional design software is becoming more common in the manufacturing environment. Large manufacturers, automobile and aircraft, in particular, are using three dimensional design software to make all their designs for new parts. They are then taking the electronic digital data and using it directly in the manufacturing process. So, the first process we can describe for the Production of Molds utilizes this three dimensiona ldesign software to directly control a milling machine. There are some lower cost milling machines of various sizes being introduced that allow this direct coupling of the three dimensional digita information to milling o f plastics. I have seen some of these inoperation making parts. In addition, I've seen some work being done to make small patterns which would be quite similar, I think, to your particular needs. One additional new technology that is receiving alot of interest, certainly in the manufacturing environment, is called solid imaging. Again, this processes uses three dimensiona electronic design data, but instead of removing material you actually build up material. Here the process, and the one that is furthest along through commercialization, is to take a container of liquid surrounding a platform that can be raised and lowered, then you use the electronic data to control a scanning laser which hardens the liquid material image-wise on the platform. The liquid that is hardened through the action of the laser light is what we call a photopolymer material. In a very short period of time you can get very accurate patterns out of this process. We have a system in-house that uses this process and, in fact, we sell photopolymer materials into this market. We have made patterns that are quite flat and that have very accurate controlled raised areas on a flat surface. This might be a process that could be used to make molds that would be quite useful for tactile graphics or braille output. So, what I've attempted to do here in just the few minutes we have, is to pick some selected technologies that might be applied to the production of high resolution tactile images. As I mentioned in the very beginning, I hope this very brief introduction will serve as kind of a starting point for conveying to you the "art of the possible" in utilizing polymer and photopolymer materials to make high resolution tactile graphics. I also hope this brief introduction has whetted some appetites in what can be done with a little imagination. I certainly thank you for your attention and I, again, must apologize for this rather inconvenient method of presentation.
Q. John Gardner: My question is really the question about what are the requirements for the inks to be able to stick to the paper . The important qualities that we are hearing about that we need in tactile printing are first of all to make sure that the thing will stick to the paper and thesharper the edges the better. Can you comment on any properties that will be useful for that?
A: Well, in order to get good anchorage, of course, the material that you put down has to penetrate the surface.That's obvious. If you have a very slick surface, it's going to be very difficult. If the material you're applying sits on the top of the paper, you're not going to have a good physical "bite". So, I would say that probably the first requirement is that it has to be imbibed or somehow incorporated physically into the surface that you're printing. It can be absorbed too much, then you get a lot of spread and your image definition trails off. The ink must have a good balance of properties. It has to have good rheological properties along with penetrating ability and it should achieve physical entanglement with the particular material that you're printing on. It would also help,too, if you could harden the ink after it is applied. The processes I am thinking about most commonly utilize heat or light; you could also have some delayed chemical reaction. That would certainly help to lock everything together. That's what's typically done in normal printing processes where you put an ink down, it's absorbed somewhat into the paper surface, and then it's typically cured either by heat or bylight. That's a long-winded commentary on your question John.
Q: Thisis Tim Cramner. Could we use a coated paper or a plastic substrate toprint on where a solvent bond would occur with the ink when it's deposited?
A: Yes, that's a possibility. I would think that if you're not going to use a paper, depending on what you want to put-down, you would have to have some sort of coating or subbing on top of your support that would be designed to be compatible with the material that you're applying. Certainly, the use of solvent in the ink would swell,imbibe or lock up the ink on the coated paper would be an approach.One thing we have to consider now, of course, is there are a lot more restrictions on the emissions that you can have. Certainly a lot of printing now is shifting over to water based systems, where the requirements for good adhesion would be even harder.
Q: Raman. I have two questions for you actually. I'll ask the first one because it's related to what Tim just asked you. One of the things we use, all use,is credit cards and if you ever tried to destroy a credit card you realize how difficult it is to break those things. We've been talkingabout tactile graphics that are durable. What kind of polymer technology would you use, if you wanted to print the tactile graphics on say a sheet of paper and then laminate it in some sense. Laminate it in a way that you can still feel the tactile graphics, where the lamination actually accentuates rather than covers up the tactile graphic that you've produced, because that clearly is going to be completely durable. Do you have any ideas on how you will achieves omething like that?
A: Yes. There actually are a number of lamination processes, but in general, you can laminate very thin materials over a raised image and, in a lot of cases, if you apply a small vacuum during the process you'll get very good confirmation of the plastic film over the image. What we see with fine patterns, and we done someof this work in our electronics products, where we actually laminate very thin plastic films over circuit board patterns which are very fine lines and spaces, is that the vacuum helps to get the good contact and to reproduce the image underneath. But, there are a lot of problems with lamination. It's very easy to damage a pattern, very easy to get wrinkles, it's very easy to get some sort of defect during the covering process . It is possible and you would have to usesomething very thin that would have good confirmation over the images yet retain a lot of toughness. I think there are a number of ways of going at the problem, it=92s just a matter of trying various materials on the particular substrate you would like to laminate.
Q: The second part of my question is, of the technologies that you described you, which of those do you think are most relevant for refreshable displays, for tactile displays that can be refreshed on the fly? I don't necessarily mean high resolution tactile graphics, but something that I can refresh very quickly. And lets say all it can give me is a raised blob or no blob. Let's say it can give me a little square that's raised and that's the resolution you're looking at. How difficult is it to achieve something like that with existing technology? I want something that is refreshable real time, not necessarily completely high resolution that I'm going to do a map on it, but something where the resolution is about the size of the button's on your calculator or something like that.
A: I think there's a lot of opportunity in the concepts I described, using some sort of thermal means to expand, and by that I mean expansion and a change the surface characteristics. There's also a lot of mechanical means to accomplish this task. These are ideally suited for computer control where you have to address a large number of different pixels or imaging elements. And I'm sure the technology is probably there to make something that would not be high resolution but certainly be usable for a lot of applications. I think you could probably use existing components, existing technology and tie them together with the appropriate control software.