I Start Inventing a Dental X-Ray Film Processor

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In 1991 I was working on a root canal for a patient in my office. My assistant placed the final film in my automatic “roller” film processor. As soon as it came out, I would be finished, and on to my next patient. The film got stuck in the roller mechanism, and didn’t come out. We took the processor apart, and found the film, which was ruined. Exasperated, my assistant re-exposed the x-ray, and hand developed. By the time the second film had been processed, I lost at least twenty minutes of time, putting me under time stress for the rest of the afternoon. This incident was the actual stimulus that got me started thinking of a new design for an automatic film processor.

The drawing above shows what the rollers in a roller film processor look like. The film has to make its way through all of those rollers, and all four sets of roller racks. The rollers themselves get “gunked up”, and damage and scratch the film surface. The film can also fall out of the rollers and wind up in the bottom of the tank, which will ruin the film. One film may get stuck, a second film can come along and stick to the first, which will ruin both films. If one set of films is in the roller mechanism placed by one assistant, and another assistant then places film in the processor, they will come out completely mixed up. It is a nightmare trying to figure out which films belong the which patient. This can lead to some bad errors, as you can imagine.

In our office, over a fifteen year period, my partner and I had purchased three different film processors for around $5,000 each, and all had really been miserable failures. The last one we purchased worked great for about three months. Then, one day, my hygienist was standing in my operatory door, as I was working on a patient, saying, “The film is getting stuck again”. What a sinking feeling. I had to leave my patient and go take the processor apart to see if the film could be saved, creating more time stress for me. It was hard to believe that these huge dental companies like Kodak, Gendex, DentX, Agfa, couldn’t come up with a better design. Film loss in roller processors was a continuing and unbelievable headache for dentists. Film processors also required around an hour a week of cleaning and maintaining, which was usually done by an unhappy assistant after office hours on Fridays, not a popular job. After everyone left, the assistant had to stay and scrub. In our office, putting exposed film in the processor was like “film Russian roulette”. You really weren’t confident that it would come out the other end. I went to dental conventions and searched for new technology and processors. There were none. One of the salesmen told me that “Roller processors are the state of the art”. Ugh. I was 100% certain that I could do better. I just knew inside that I could come up with a better film processor design than my highly hated roller processor; kind of like someone knows they can paint, or write. Most people know they have an internal talent, whether they actively use it or not. It may be art or music or the like. Mine was engineering.

One day I was playing tennis with a very close friend, John Devlin. I told him about another good friend, Mike McCoy, who had invented and patented a door trim that could be manually extended out to prevent parking lot door dings. Mike called it DefenDoor, and I really thought it was a sensational idea. I told John that I really thought I could make a better film processor than the units currently on the market, and I explained about all of the problems with the current technology. John said, “Why don’t you and I form a partnership, and we can do it together”. For a lark, I said,”Great!” We wrote up an agreement. I was to be a 60% owner, and John was 40%, since this was going to be my “thing”, and all testing, if there was any, would be done in my office, if we got that far. I knew when we made this agreement that the chance of actually making anything of value was nil. I figured I would do this for a couple of weeks, we wouldn’t come up with anything, and that would be that.

A primary criteria for a processor that I would attempt to design was that it would allow the user to access their film at anytime during the cycle, so a dentist wouldn’t have to wait seven or eight minutes before knowing that the processor ate the film. I thought of a round tank with a rotating arm that dipped film into different sections. John came up with the idea of a washing machine.

The First “Processor”!

I Start Making Prototypes

John came over to my house on a couple of occasions with ideas which he had drawn up. It was obvious that John was a chemist, which he was, and a good one, and not a mechanical engineer. His ideas were DOA; not worth even trying. I kindly tried to explain that to John. A few weeks later I was standing in front of the commode and looking at the toilet tank and bowl design. It was composed of a tank above, flowing water downhill into the bowl. I visualized, what if there were two toilet tanks above one toilet bowl? (see above.) The two chemicals, developer and fixer, would be stored in the tanks. Film would be placed in the bowl? A valve would open and, using gravity, flow chemical into the single reaction tank (bowl). The chemical then could be pumped back into its storage tank. Then the bowl (reaction tank) could be flushed out. Next the chemical in the second tank would do the same as the first, followed by the washing of the bowl (reaction tank) again. Then a blow dryer would dry the film. It seemed so perfect. And, I was excited. It seemed like a good place to start. Using gravity to flow the chemical into the reaction tank would mean that there would be minimal parts. Mother Nature will be doing all the work.

I started making prototypes, the first ones using waste baskets and Tupperware containers. I placed the waste baskets filled with water on a wooden shelf above the Tupperware container . I connected the two with a clear PVC tube and a valve. When I opened the valve, the Tupperware container rapidly filled with water, just as I had envisioned. I then started substituting cut acrylic tanks for the Tupperware. Step one was complete. The next part, getting the chemical back would prove to be more difficult.

John came over a few times to see how things were going. He was in love with a pretty lady at the time, and his free time was consumed with her. As I worked several hundred hours, he spent only a few, looking over my shoulder. He really had nothing to add and he was too busy with work and his girlfriend to spend much time on the project. It was obvious that this was going to be my project, as it should have been. I had ordered pumps and other parts, for which I gave him a bill of $280, which he paid. I would be working at 1:00 in the morning in my “lab”, and he, understandably, would never be there. After thinking things over, I could see that John was not going to be of any help on the project, and it was just going to cost him a lot of money, which he would lose. I sincerely felt at the time that there was no chance of success, and I was going to have to get money from John, his 40%, on a continual basis. I was willing to put up the money myself for what I envisioned to be an expensive hobby, and I really felt bad that I would continually have to ask John to ante up. We went to dinner one evening. I presented John with a check for $280, and said that it would be best if we dissolved the “partnership”. John took the money, and agreed. I thought he would be glad to be out of the project, but I sensed that he was not happy. That evening was the end of what I considered to be a great friendship. John wouldn’t play tennis with me anymore. He stopped being my patient. He basically ceased all communication with me.

I went back to trying to figure out how to get the liquid back up into the storage tanks. I first tested pumps, but that idea vanished quickly. It was too slow, plus I found that the bearings wouldn’t fare well in the corrosive environment. One day I was vacuuming my garage. I wondered what a vacuum might do to bring the chemicals back into the storage tanks. I put a plywood lid with a hole in it for the vacuum on the waste baskets that I was using at the time. When I placed the vacuum nozzle into the hole in the plywood (C in the above right drawing) lid and turned it on, the chemicals “flew” back. The connecting tube itself was dry. I closed the valve between the reaction tank (Tupperware container), and storage tanks (waste basket) and trapped nearly 100% of the liquid in the storage tanks. I was off and running.

One major problem that I saw was that, with any processor, if even one drop of the fixer chemical contaminates the developer chemical, the films will come out foggy and ruined. So, while I had found a way to get the chemical back into the storage tanks, I was certain that flowing both chemicals into a single reaction tank would very quickly cause contamination of the developer. I was having fun getting the water to move from tank to tank. I never tried processing film with the prototypes because I didn’t want failure just yet, even though this loomed as a huge problem. I wanted to continue with the design more for the fun of doing it than anything.

I Go For A Patent

I went to Mike McCoy’s (DefenDoor) patent attorney, Kent Stetson, to see about patenting my design. I spent a great deal of time going over my device with him. I took a developer prototype to his office, and carefully described how it works. I told him my device has no pumps which he noted. Other patents already showed pumps to move the liquids. He wrote furiously the whole time I was explaining it. He seemed so thorough. Kent said it would be best to run a patent search first, which would cost about $900. I agreed, and waited with baited breath for three months. Inventors are, of course, always worried that someone in the world will come along with the same idea, and patent the idea before they do. When I got the search back, there were already nine patents still in effect that looked like my design, none of which were successful. I was so disappointed that I threw the sheets across the living-room. They fluttered down in a giant mess. I thought I was finished. The next morning I got up and picked up the piled mess of papers that I had made the night before. I looked at the details of the patents. All of them were like “washing machines”; like John’s idea. None of them moved the liquid like my design, by gravity flow forward, and vacuum return. I suddenly became reinvigorated. The project was still alive! In fact, most of the designs were not prototype-able, as the designs were so ridiculous. They simply could not have worked. It was almost as if the “inventors” came up with ideas and patented them without any tests or prototyping, in case they “had something” a company might use. Possibly some of them wanted “trophy patents”.

Kent recommended that we go ahead and start writing a patent application. I waited three more agonizing months to get the patent draft back. When I read it, I was amazed. It had the word “pump” in about 25 places, after I so clearly explained that there were no pumps at all in the design. And the description of the device was horrible. Kent had no idea what I was patenting. Did his secretary write it? Knowing that it would probably take another three months for Kent’s office to do a rewrite, I immediately sat down and started rewriting the patent myself. It took a couple of weeks to complete. I took it to his office for corrections and “legalizing”. Kent wanted to charge me another $1,800 for doing so. I told him he wasn’t going to get paid. He kind of embarrassedly agreed. He made the corrections, and sent in the patent application. It takes a couple of years to get a patent application through. I had to patiently wait for the news to come back from the USPTO. I continued working on my design.

I ran into my ex-friend John walking on Balboa Island one day. He loudly scolded me for cutting him out of the project and not putting his name on the patent. He didn’t realize that putting his name on the patent would have cost him over $5,000, his 40% share. John naively thought he had been a big influence on my design. I really do miss the friendship, the laughs, and the tennis that we had. But, John, if you ever read this, I saved you hundreds of thousands of dollars. Our “partnership” would have ended, only later when things would be far more difficult. Our relationship would have been the same, only in reverse, if we had been trying to develop something in your realm of expertise: chemistry. I would have been the “watcher”. So what I did was best for you, and me.