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About Erich Länger
Erich Länger studied at the University of Vienna and joined Philips Austria in 1963, where he stayed until his retirement in 1996. During his time at Philips, Länger concentrated on video recording equipment. In the interview, he recounts the milestones in the technology, from the EL-3400 – which only recorded in black-and-white and required threading the tape through a drum – through the Video 2000 cassette system, which recorded in color. Cassettes were implemented with the NT-1500, color with the NT-1700. He also compares the various systems' consumption of tape, recording capacity and tracking systems. He emphasizes the revolutionary dynamic tracking system developed for the Video 2000, as well as the laser-cut technology for manufacturing video heads that became widely adopted. He argues that the Video 2000 was in many ways superior to both Betamax and VHS, which were more successfully advertized. He closes by looking to the future of video recording, including DVHS ("Data VHS") tapes.
About the Interview
ERICH LÄNGER: An Interview Conducted by David Morton, IEEE History Center, July 25, 1996
Interview #288 for the IEEE History Center, The Institute of Electrical and Electronics Engineers, Inc.
This manuscript is being made available for research purposes only. All literary rights in the manuscript, including the right to publish, are reserved to the IEEE History Center. No part of the manuscript may be quoted for publication without the written permission of the Director of IEEE History Center.
Request for permission to quote for publication should be addressed to the IEEE History Center Oral History Program, 39 Union Street, New Brunswick, NJ 08901-8538 USA. It should include identification of the specific passages to be quoted, anticipated use of the passages, and identification of the user.
It is recommended that this oral history be cited as follows:
ERICH LÄNGER, an oral history conducted in 1996 by David Morton, IEEE History Center, New Brunswick, NJ, USA.
Interview: Erich Länger
Interviewer: David Morton
Place: Vienna, Austria
Date: July 25, 1996
The EL-3400 Video Recorder
This is an interview with Erich Länger, the date is July 25th, 1996, and it is taking place in Vienna. Herr Länger, why don’t we start with a little bit of information about your upbringing and early education.
Yes. I studied at the Technical University in Vienna, in electronics, and I started in 1963 at Philips with basic developments and the release of products, of video recorder products. I joined this group when the first video recorder — the first consumer-oriented black and white video recorder, EL-3400 — started here in Vienna. It was released in the year 1964, and from that date onwards I was always in the group of video recorder development and later on as a manager for projects. I worked until July of this year, when I retired, so I was from 1963 onwards always in the field of video recorders, active in the beginning of the development area and later on in project management. So, the real start of my work was on the first video recorder, the first consumer-oriented video recorder, black and white, in Europe, I have to state, EL-3400.
Was there a predecessor, did Philips have professional video recorders before that?
No, a semi-professional video recorder was made out of this product later on.
So this was the first video recorder Philips made?
Yes, yes, there was no predecessor. All the basic things, like video heads and such things, had to be also developed and produced for these sets, and for these basic things, Philips Eindhoven gave us a lot of help. So the development of video heads basically started in Eindhoven and was later on transferred to us here in Vienna.
Why did they transfer it to Vienna?
Because the basic development started in the research laboratories in Eindhoven, we did not have those possibilities, to start with such a basic development, on ferrites, on the material, especially, on the technology to fit a video head together. No, the basic technologies were worked out in Eindhoven, and later on we produced and further developed those technologies here in Vienna. So also the basic development afterwards was continued in Vienna, especially for video heads, because the video head is the heart of the video recorder. The other things around are similar to other products in the consumer area, but the video head is really the heart. And the video head’s development is an important part for a video recorder. So we followed later on completely with our own developments here in Vienna, also on video heads, and on materials and on choices of technologies. Though this first video recorder I released here in Vienna, at the end of 1964, this product started with a certain market introduction. It was a, let’s say, very huge, heavy machine, weighing 40 kilograms, big in size, was built up inside with tubes and transistors, mixed technology. So tubes at that time for the high frequency area, and transistors for the low frequency part. It was a reel-to-reel machine — that means no cassette — and used a 1 inch tape.
Was it a special tape just for video?
It was a special tape, yes, but it was also similar to other tapes also used for recordings in the field of digital recordings. At that time it was only used for computer applications. So it was a little bit similar to computer tape. It was very interesting that this video recorder, this huge video recorder, could only be used together with a certain TV set, because this video recorder had no receiving part inside, so you could only receive signals if you had it connected in parallel to a TV set and you had switched on the TV set, so at that time it was only possible to record the picture you see on the TV set at the same time, because no "front-end" part, as we call it, was included in the video recorder. So it was only parallel recording to that what you see, and this video recorder did not have a switch-clock or a timer, so there was no timer-recording possible at that time. Only recording when you were available at the same time was possible.
It must have been — the whole system must have been very expensive.
Yes, I do not know the price at that time, though it was not so expensive. But it was interesting that the signal was fed out from the TV set by using a metal cap which has to be put on a certain tube in the TV set, the RF tube, where the RF frequency is available, it has to be found in the TV set, this cap has to be put over that tube, and then the IF signal was fed out by a transformer for mains isolation only, a small transformer inside, and this signal was then demodulated in the video recorder, and then recorded.
Only black and white. There was no color system chosen at that time in Europe. So this feed-out loop via a tube in the TV set says that also the TV set must have been a TV set with tubes. Otherwise you could not couple out your signal. I think later on there was also another possibility to couple out the signal from the TV set.
Was it just a — Was it inductive coupling?
No, capacitive coupling.
Yeah, a cap, a metal cap over a tube. So only capacitive. And RF frequencies in the area of 30 to 40 Megahertz. So in this area you have capacitive coupling very well. And it was detected and demodulated in the video recorder. For playback, a small modulator was built into the video recorder, and also a video output was available for a monitor. So if you have had a monitor you could directly connect a monitor to it, but on the other hand RF output was also available to see the picture during playback via the TV set antenna aerial. So this video recorder containing seven motors was very heavy, as I already mentioned — a few motors only were used for cooling. [laughter] I think two motors of those seven were even more used for cooling purposes, and also the playing time, I think it was in the area of one hour. Ah, forty-five minutes, it started, excuse me, later on, I think, when the tape was thinner it was also possible to play for one hour, but it started with one-inch tape, forty-five minutes playing time, and black and white only. But this video recorder could have been used really by a normal consumers, and it was at that time also used by normal consumers. This, I have a picture of this.
Do you know how many of these were sold?
It was in the range of 4,000 pieces, I guess. So a quite low quantity. You know that at that time, nearly at the same time, the audio cassette appeared, in 1963. I was not, was never involved in audio, but it is of interest that in 1963 Philips introduced the audio compact cassette which is widely used even today, and it was not a basic development here in Vienna, but I think the first small audio tape recorder was also developed here in Vienna, in the same factory because we were in an audio factory, the BGW (Bandgerätewerk), a tape-recorder factory, and the first application of this compact cassette recorder I think was also done here. Maybe Mr. Drabek knows a little bit about it and Mr. Kretz maybe has a model of this first tape recorder. I had such a model in my office too. So, there was also a small recorder developed at the same time. So you can see here in Vienna the introduction of audio and video took place in 1963, 1964, nearly at the same time. And in both cases basic developments: the first, the audio cassette, survived; the other [laughter] did not survive because this reel-to-reel tape recorder only was used for introduction of video recording, basically, but it was not widely used and it was not really to be a success, but it was a starting point. And later on a lot of developments followed, and as you know, we are now producing millions of tape recorders here in Vienna, and in Hungary, and in Germany, in the IR3 company, coming out of all these developments.
Well, the next video recorder was a quite smaller one. It was the EL-3402 video recorder, with an improved concept, smaller, and easier to use, but also reel-to-reel, it means no cassette, and you have to put your tape in by hand. In the first video recorder it was rather complicated because the upper drum unit has to be held by three bolts, and you have to feed the tape through the three bolts, between the three bolts in the drum unit, so it was complicated. In the newer video recorder, EL-3402, it was easier. You have to put the tape around a drum, in an easy way because there were no bolts. The upper drum was hold, has been hold inside by the axles, and therefore you could put in the tape much easier, but anyhow you have to thread in your tape by hand. The 3402 video recorder had also improved performance, but also black and white in the beginning, and reduced tape consumption, it is written on this photograph as well. You can see that EL-3400 has a tape consumption of 17 square meters per hour of tape. This newer design had only 11 square meters per hour necessary, but still quite an amount of tape to be used. Though this video recorder could be easier carried by a hand grip, and this recorder had really much more an impression, gave an impression of a consumer-oriented recorder, and it also winded faster and less tape was necessary.
So it was really an improvement. I think it had only three motors or so, fewer motors, and improved electronics, that’s clear. It was fully transistorized, no tubes at that time, but also no RF part included, that means recording and playback via video signals only. I do not know if a modulator, a transmitter was built in. I’m not sure about it, I don’t think so. I have more detailed technical information with me on all these video recorders. It was easier to handle, a nice arrangement, electronically controlled. So this video recorder was a big step forward, but it was still not a real consumer video recorder, really, if you take it in relation with today’s recorders.
So a third step was under preparation within a short time, and this video recorder, called LDL-1000 was then, you might say, the "real" first consumer video recorder. It was a small box with a hand grip, and a half-inch tape used for the first time. This video recorder, was really called by us "home recorder." I have also this video recorder on a photo. Very easy to guide the tape around the drum, also to be done by hand, no cassette, two reels, but half-inch tape, and it could be easily guided around. This LDL 1000 was also produced by Grundig. The Grundig name was BK-1000 video recorder, was first shown at the Hanover Fair in 1969, but this recorder had smaller reels. It only was able to record forty-five minutes, with thinner tapes later on a little bit more, but it was quite a short playing time. For a normal transmission it’s not sufficient to have 3/4 of an hour on the tape only. And also only in black and white.
Did these — How did these two sell? How well did they —
They were widely sold, though those video recorders had quite high quantities, and it was really used as a home recorder. I don’t know how many thousands, but anyhow it was in the range near to 20,000 or so, in that range. But still, fully transistorized, that’s clear, still had to be controlled by hand, with three knobs. You had three control meters, one for video, one for audio, and one knob was I think for playback tracking. So you had to control the recording during record by two knobs, audio and video, but the system itself was quite close already to the systems which followed later on. On the tape, helical-scan recording was used by all the former sets as well, but the track width, the audio track, the control track, were very similar. So the system gave the parameters quite close to the newest parameters which are used now. This was a real development in the right direction, and also widely accepted by the consumer because of its tiny, nice box, so you could easily carry it with you, but it was still related to a video source from outside, because also no receiving part was incorporated in this LDL-1000.
Did Philips sell a camera to go with this?
Yes, a camera was also available at that time to be used with this, but it was only black and white.
Was that popular?
Yes, it was also arranged — also sold together with a camera. Some sets were available to be used just for home use, but all black and white at the time. But yes, there was an application with a black and white camera at that time. So those were the three really basic sets, developed and produced in Vienna. I’ll give you the photos. And also, Grundig made some advertisements at that time for that system, and that recorder, but it was not a cassette system as it is now, but it was a really good starting point to continue. And then we continued with our first cassette recorder in 1970 as given here in the paper, we made the development together with a lot of other companies including Grundig, Standard Electronics, Sony in Europe, Sony UK, and Studer in Switzerland. They did not really develop it together with us, but they really gave their inputs to build up the new VCR system, and it was at that time really called VCR system and VCR cassette, because at that time video cassette recording was not known, so it could be used, this name, VCR. Now VCR could not be used because of various systems all using a video cassette, but at that time it was the only video cassette system.
Video Cassette and N-1500
And this cassette, I have it here on the table and I’ll give it to you, contained half-inch tape with the reels separated from each other, one reel on the bottom side, the supply reel, and the take-up reel on the top side, and half-inch tape gave in the beginning a playing time of one hour. So one hour VC-60 was the starting point for that system. So one hour was at that time seen as the minimum length for normal consumer-oriented recordings. But even one hour was too little. Later on so it was necessary to extend the playing time further, but this cassette system started with one hour’s playing time with half-inch tape. This, the related first video recorder was called N-1500. This N-1500 video recorder was then the real first tape recorder which could be used without a television set in parallel, because this video recorder already had a tuner part incorporated, and a transmitter part incorporated, and a switch-clock, a mechanical switch-clock at that time, to be used, so this video recorder N-1500 was able to record from aerial directly, and an aerial loop-through was also made by this recorder to be fed through to the television set, and not to change your cables between record and playback, so the same connection can be used for playback, and this N-1500 was VCR system, with VCR cassette, was then introduced in 1972, in September.
So out of this N-1500 set a lot of other sets were made to be introduced also in other European countries, but although this set was widely sold all over Europe. So it was also introduced in the UK, where the television system is a little bit different, as you know, so all these things were a little bit new, because this system and this recorder was, I can say, for first time really widely spread over Europe. So that was the first video recorder used by other companies, with their name plate on it, you can see, or a few small modifications, but basically produced by Philips but introduced by others with their name plate to have it widely introduced in the market. And it is listed up here which companies did use it. N-1500 also consumed less tape consumption, later on I can give you all the figures if you like. I already mentioned the tape consumption on the former sets, but this set reduced tape consumption some more, was easier to operate, had a switch-clock control, and an RF part included. So for the first time you had a complete home recorder with all the things equipped, with all the things which are used today as well.
So this set really fulfilled for the first time the full requirement of the consumer because this set could be used independently of a TV set. The big disadvantage of this cassette was that the tape could not be wound or rewound in the cassette as well. The tape always had to be threaded in around the drum, and then winding rewinding could take place, because of the two reels being apart from each other, which cannot be used for internal winding rewinding because of this configuration. You see that the tape is not in the same area, in the same height, so therefore winding and rewinding could only take place in the video recorder, and only by threading it around the tape. It’s for you. But this system really was widely introduced. It consumed 6.5 square meters per hour, so still nearly half of the tape consumption of the previous one. But although this system did not survive, therefore you can see other, introduction of other systems on my list, but I think I will concentrate really on the developments of Philips, where I was working on and for a certain time also responsible.
Video 2000 and Dynamic Tracking
That means the next development really widely used in Europe was the Video 2000 cassette. I do not have a cassette with me, but I guess that you can still buy it somewhere, in the shops, Video 2000 cassettes are still available because the system is always still in use by some consumers. I have a recorder at home, and I still use it. In the school where my wife teaches, the Video 2000 is still used. So the system exists, but it has been a long time since the tape recorders produced for the Video 2000 system. So the Video 2000 system was introduced in 1979, at the Berlin fair, and it was the first cassette which could be used on both sides, that means a flip-over cassette, if you came to the end on one side you could turn it over and record the next side. So the half-inch tape was basically used quarter-inch, that means only half of that tape was used for one direction, and then the other direction came. And therefore the track-widths of the video tracks had to be half of the track-width of the previous recorders at least, so we reduced the track-widths to 22 microns, so it was a very narrow track.
So this narrow track meant that precise tracking could not be achieved only by keeping mechanical tolerances within certain, in a certain range. Since between different machines and you have to have interchangeability full, fully on all machines, it was necessary to develop a new system which was called DTF, Dynamic Track Following. So the video heads were not placed in a drum unit in fixed positions, they were placed on a so-called actuator that was a ceramic element, which could be bent by applying a certain voltage on it. So if you supplied this piezo-ceramic element with a certain voltage, this bending moved video head to an upper or lower position on the drum unit, that means the video head could be controlled electronically in a vertical position relative to the video tracks. So in a vertical or transverse way the video heads could be controlled. So you have the tracking in one, in this direction, the control of the video head could be in normal, or in a vertical position to that tracking —
Longitude, longitudinal direction.
Longitudinal tracks could be controlled in a vertical position by the video head. So the video head could find its real position on the tape, but it was used also during recording to have real record parallel tracks in recording. In recording the head stayed in a more-or-less stable position. It was only a static adjustment during recording, though the track widths were equal on both heads. The video heads are 180 degrees apart on the drum unit. But during playback both video heads could follow the tracks automatically in a dynamic way, so even if the track was bent in an S-curve or something like that, or if the recording was made on a completely other video recorder, the tracking could be achieved by those piezo-ceramic elements. So this system was really a new system.
At that time, 1979, already other Japanese systems appeared. It was Sony Betamax in ‘75, and one year later JVC, which is now twenty years ago, just twenty years ago. But when Philips came out, and Grundig and also other partners with this Video 2000 system, it was a real revolution from a technical point of view. It was promised to the consumer that this system guaranteed 100 percent interchangeability on the system side, not only by mechanical accuracy, but also by electronic control circuitry, whatever it is. Yes.
Interchangeability and Video 2000
I’m not sure I understand interchangeability from the system side mean.
Well, it means DTF system, which is incorporated in Video 2000, guarantees interchangeability because of the movement of the video heads, so the system itself, based on this dynamic track following, guarantees that all cassettes are interchangeable.
I see. And that’s interesting. Why is that so important? Was it expected that people would be exchanging cassettes?
Yes, yes. Interchange of cassette was expected to be an important factor in videotape recording, especially in home recording. This was because recordings would be made by copying houses. Software did not exist at that time, but it was expected that any video software that would appear in the future would be playable on any recorder. And this should be guaranteed by the system, not only by mechanical accuracy of the equipment. You can imagine that tracking a 22 micron track accurately is not very easy to achieve from a mechanical aspect only. So dynamic track following was a system which easily could be explained to be a 100 percent interchangeable system for all cassettes, for all recordings. Also for maybe, software, which came up later on, and did not exist before that. There was no video software that I can remember, on other cassettes. On VCR cassettes, yes, the first cassette system. Also some software existed.
We made so called copying machines for the VCR system, that were specially aligned machines with special long-term parts in it for long-term use. So because first cassette system was already meant to be interchanged because of the easy handling of the cassette. So on this N-1500, I remember, we also made copying machines, and those machines did not have a receiving part in it. It was also a smaller machine, a little bit narrower, because of the missing RF part, because it was only for video in/out, because copying was made naturally, only by using video in/out signals. And it was also used in racks, in 19-inch racks, stacked, so you could really record in parallel on a few recorders, for software could easily be recorded.
Do you remember what kinds of things were available at that time? Were they motion pictures?
What kind? No, it was, I think, basically for education. As I remember. For schools, software was produced with cameras. I did not mention that this VCR cassette system was the first to introduce color recording. It was, in the older system, only black and white was used. By the way, I developed an adapter for recording color on an EL-3402 machine, by using the black and white input, and also during playback the adapter was used to achieve color signal in playback then, again.
How did that work? How did you do that?
It was a modification of the color television system. It was a sequential system. So in one line only the red color component was recorded, in the next line the blue and the green. The three colors used in the color system were sequentially recorded, in each line. And during playback it was, this information was delayed in delay lines, and sequential signal was again brought back to an analog signal, but with some restrictions. It was not a perfect system. It could not be, because it was incorporated in the luminance signal. Color needs less bandwidth, it’s clear. Therefore it could be easily incorporated in the luminous signal. The rest of the black and white bandwidth was used for the color information, so it was a split up of the whole bandwidth for luminous and for color. So it was a quite complicated system with delay lines. A sequential system has all sorts of disadvantages, because if you have had a color in the vertical direction, then it was horrible, because this was delayed two lines later on, so it was really only to show that color could be made available, but it not widely used. It was really only to show that color recording is possible, but it was not widely used. Only few pieces were made. But first color was introduced in N-1500 VCR cassette system.
Now the color system which was first used in the first N-1500 set was already very similar to ours, to the system which is used just now. The "color under" system, as it is called, color is mixed to low frequencies and recorded, in addition to the frequency modulated luminance signal, and it is the luminance frequency signal that is used as a bias for the color signal, and the color signal is an amplitude modulated signal, and the luminous signal is a frequency modulated signal, so you can easily split it later on. And as it is used now, the chrominance signal is later on mixed again back to the higher frequency, and then again added to the luminous signal, so color and luminous is also split up into these systems. But this system was already used first time in this video recorder. So all systems, if you look to Betamax to VHS, have then used this basic principle.
[End of tape one, side one]
Tape Consumption and Tracking
So this N-1500 you could really see as a basic development on the mechanical side as well as on the electronic side, but mechanically later on, all systems joined the planar system of cassettes, that means the reels in the same plane, with the winding, rewinding inside the cassette. This was possible in the Video 2000 because Video 2000 had two reels in the same plane, and Video 2000 also had some new things which were incorporated all the system. Like the automated detection of tape length, as I already showed you. You could easily protect a recording by moving a lever, and you could remove it again, as it is widely used also in cassettes. Also VHS did not have a copy protection device which could be re-activated, activated and re-activated again. Not to break it out only, and put a sticker on it if you like to have it again.
But, okay, again, to Video 2000. Video 2000 really less tape consumption, reduced tape consumption because tape was used twice, [laughter] so it is unbelievable that all these things went down half a square meter per hour. If you relate this to former systems it is quite a factor, yes? And it is still, it was and still lower than VHS today. VHS, in the long-play mode, okay, comes also close to that. But the tape consumption figures listed on this photograph are I think related to the NTSC system, maybe in power it is a little bit different. But I have also a picture showing tape consumption, but it is a very technical item, and I think it could be easily followed by everybody. If you compare the tape speeds of various systems, then you can easily compare the systems, and the tape speed is well known. And all systems later on came to a so-called long-play mode, meaning half tape speed, double playing time, but also half widths of video tracks. So the video tracks with dynamic track following accurately scanned, and that was a big achievement at that time. It cost a little bit more because of this actuator, this ceramic element, that’s clear, and the control circuitry around it.
It was electronically detected by the video head, the position, the vertical position, and then controlled. There were extra signals recorded on the tape, low frequency signals, various signals in different tracks, so the track was followed, and the adjacent track gave a cross-talk to that original track, because of low frequencies. Low frequency has a big cross talk from adjacent tracks. And this cross talk was measured and compared, and was controlled to equal. So the basic principle of dynamic track following is to control the video head in such a way that cross talk from the adjacent tracks is equal, or will be equal, and to do that in a dynamic way, so controlling it also done during the scanning of the track, not only track by track. So it is not only a the tracking potentiometer, which controls only in a static way, but it is also controlled in a dynamic way, therefore the name Dynamic Track Following.
Has that invention been picked up in other systems? Do the Japanese companies use that now?
No. Also if the tape speed is completely outside the normal standard, track, speed, for scanning reasons, scan-forward, scan-back, then the tracks are completely out of control in a normal way, but by dynamic track following you can even follow those tracks in high-speed modes.
Displacement by Betamax and VHS
That was always a big advertising claim. No streaks, and so you can make good advertising for that system because all those features were available in a better way than it was shown by the other systems, systems Betamax and VHS, which had already come out in Japan and America, and later on also in Europe. So the big advantage could be shown to the consumers, and the consumers very well accepted that. So it is a pity that Video 2000 did not survive. They, Video 2000 was licensed to a lot of companies in Europe, which sold Video 2000 tape recorders under their own names. But later on the systems coming from outside, from Japan, the States, were more heavily advertised. VHS won the big fight on the system level. That is true. But for technical, from a technician’s point of view, Video 2000 was still the best system and also for advertising reasons it was unbelievably good because of its features and their impact. It had perfect still pictures, no extra heads required. All these things where you need extra heads, and extra things in other systems were not necessary in Video 2000, because of this Dynamic Track Following system. There are also a lot of patents on Philips’ side on this system, so if you look at patent, the patent situation on the Dynamic Track Following system you going to also find a lot of patents on this side by Philips, our company.
=N-1700 Long Player Video Recorder
I forgot to explain, that even before the start of Video 2000 in 1979, we made a system based on the VCR cassette, the so-called N-1700 long play video recorder. It had a longer playing time, not just one hour. We changed the parameters on the tape, but we used the same cassette, and this machine was called N-1700, it was the long-play version of the VCR system. It was the first to use azimuth recording — that is, video heads with tilted gaps, so you could save space on the tape by recording track on track without spaces in between, without guard-bands in between, but this recording track by track made it necessary to have azimuth recording, that means tilted gaps. One track tilted in one direction, next track tilted in the other direction. Cross talk from adjacent tracks was reduced a little bit by the angle of the video head. This cross talk depends on the frequencies, and it is reduced more higher frequencies than for lower frequencies because of the filtering effect of the azimuth system.
I think it could record for about 130 minutes. So a little bit more than 2 hours was achieved with the N-1700, in the same cassette size. So it was a little bit more than the factor of 2, because of the parameters we chose. The tape speed was not half of the tape speed, it was a little lower, and therefore 130 minutes for the 60 minute VCR cassette. Yes, for azimuth recording and especially for Video 2000 we had to use narrower video heads. The video head normally is a little bit wider than the track, and the new track always over-writes a little bit the track which has been written before.
Laser-Cut Technology for Video Heads
But to have accurate track widths we developed new technology, the so-called laser cut technology. The video head itself is not made as narrow as the track, because then the video head would have been very unstable. If you would have a video head with a head width of 22 microns it would break instantly because it has no strength. So therefore, we used much wider video heads, and reduced the track widths only in the area of the gap, since only the gap is reading and writing. The rest is only for mechanical reasons, for the windings to pick it up later on. So the track width was reduced only in the area of the gap, but not in the way as it was normally done by the Japanese, by grinding the ferrite.
We did it later on by using laser technology, using a laser beam, with high energy to be applied here in this area and the material disappears because of high temperature, yes? The laser beam was used to cut the ferrite material. Ferrite is a very very hard material, as you know, it is ceramic, with iron in it. It is, it is not only iron, but also manganese, zinc, and other things to give it the right magnetic properties. But this ferrite material is very hard, because it has to be very hard to be used for hours. It must be as non-abrasive as possible. A video head should last for hundreds or thousands of hours. So ferrite was necessary for that reason, to have the video heads that last for a long time. So reducing the track width in the area of the video gap by using a laser beam was I think used for the first time by us, and is still used now. It is the best way to do it. The video head is already fixed on the drum unit, there is a winding, a spool behind it. All of it is completely fixed. The video head operates already, and then the track width is really done by applying this laser technology to take away the extra material on the sides. So I think we still use a 200 micron head width, and we reduce it to that amount which is necessary for the normal track width, which you see in VHS is in the area of fifty microns, forty-nine or so. For long-play it should be still narrower, because narrower tracks work better with narrower gaps. For reading you need narrow gaps. For writing you could have sometimes also wider gaps.
But this laser technology, is a basic technology developed by Philips you can say, and I think by Philips Vienna. It must also be patented somewhere. But it is a technology which gives optimum results, and has less risks to it. It is so easy to apply. You can control it on the spot because you have a microscope, and you can watch while you are applying the laser beam. You see it melting, it disappears, the material, and it is really melted on the spot. It is really technology which offers wide opportunities. It could be the case that later on that the glass is melted again in this area, to give it more stability. So we also use it sometimes to fill in later on, besides the gap, a little glass area, to have more stability, because it shall not break in this area. I have a lot of nice photographs of these things, but I do not have them with me. I have a lot of photographs which show video heads in this configuration, but used width partly reduced only in the gap area. And it’s much more complicated to do this by grinding, and to do this before melting the gap and all this. So we know that this technology is a big advantage.
Was it difficult to create the machinery to do that high volume?
No. No, no. It depends only on the laser beam you have to have, the rest is done by automatic digital controlled. It is done automatically. The video head, or the head disc, is put into a certain machine, and then it is done automatically. It’s done on the belt, on the production belt, in our factory here directly. So it can be used, really, in a mass production area, so it’s not only for use in the laboratory, or a clean room or so on. It is really done on the production line. But it has big advantages and we are still using it. The track width is not always as narrow as Video 2000, but still it is in the area of 50 microns or less. Okay, then, I think the whole story changed with the introduction of VHS system. We started producing the VHS system, but built our own recorders with special features. The system itself was described in the standards papers, and the standard has to be followed. We were licensee of JVC from the beginning, and, okay, I think it is not necessary to explain much more about VHS. As I already mentioned before, we have a range of sets modified every year, or nearly so. Almost every set is modified a little bit, and looks different every year. We have generations every year, of various sets, for our company, but also for other companies under their brand name, and at the moment we are in the range of about 200 various designs of VHS recorders per year. It is about the range we are producing here in Vienna.
Future Replacements of VHS
Is Philips working on the next generation, something to replace VHS?
Naturally, naturally. It is clear and it is no secret that there exists a working group for future systems, especially called DVC, Digital Video Cassette, in various sizes, already available. There are already digital recorders available, and now a camcorder was shown, at the last exhibition, by JVC, at the Chicago electronic show I think. DVC, digital video cassette system is already completely standardized and agreed upon all the system companies. Philips was widely involved in the development of the system, so the next step is prepared, but it will also be a widely used step by all main companies. So I would guess that no company will come out with a single system, or it will always be a worldwide introduction and it must be done by a combination of all the impacts of the various companies, and you know where the companies are sitting.
And anyway I can imagine that a visit in Japan to follow all this history would be very interesting for you, because a lot of things started in Japan, and were taken over later also at, in Europe. Always the systems started in Japan and the States and later on in Europe, in this order. But for the future systems I think it will be a little bit different. But digital recording itself is now already agreed upon on DVC, and is also agreed upon on VHS cassette, but it is a DVHS, does not mean digital VHS, it means data VHS. And this word data already means that various kinds of digital signals will be applied on VHS cassette in various forms. It depends on the data which have to be written on the tape. So VHS will be followed by a digital system that is mechanically the same size, meaning the same size of cassette, maybe also the same tape quality, I do not know. I expect it will have better quality because of the higher density which digital requires. But digital means will be applied in VHS also, but as a data VHS system, depending widely upon the availability of digital sources, because coding and transcoding is a very expensive thing.
It depends very much on large size ICs, so if data recording can be done by simply modifying the incoming data package to be recorded and to be played back, then it will be used. But coding and transcoding from analog to digital and data reduction is a very complicated thing. To reduce the data rate which will be necessary if you digitize an analog signal — you have a lot of digital information available, but you have to reduce this data to a certain amount to be recorded. And later on you have to do the same thing backwards. And this data compression and expansion requires very complicated IC procedures. It is all well known how to do this, but to do it in a simple, effective, and inexpensive way is a problem. So digital recording in any way will start with data recording, by using data already digitally coming in and also digitally going out. So that is my expectation for the near future.
In the far future also transcoding will be done from analog to digital and also vice versa, that’s clear. Okay, you see that the history also given on this chronological table started with the first laboratory in 1959, founded here in the Bandwerk, in Vienna, and continues now. It is all concentrated on VHS now, naturally. VHS, the modifications of VHS which we followed and improved, and also digital which will follow, so we were completely involved in all those developments. If there are basic developments, Philips Eindhoven is very much involved. But let’s say all things which are closer to real products were done here in Vienna because we have a big development department and a nice huge factory. You will see it if we go outside this afternoon, you can see the factory. And we have factories here and in Hungary and in Nuremberg, where we are producing our video recorders.
Okay, that is all the history I can tell you without going into too much technical detail..
No, there’s never too much of that. [laughter]
I hope you can use this information.
I’m sure I can. Thank you very much.
- 1 About Erich Länger
- 2 About the Interview
- 3 Copyright Statement
- 4 Interview
- 4.1 The EL-3400 Video Recorder
- 4.2 The EL-3402
- 4.3 Video Cassette and N-1500
- 4.4 Video 2000 and Dynamic Tracking
- 4.5 Interchangeability and Video 2000
- 4.6 Color Recording
- 4.7 Tape Consumption and Tracking
- 4.8 Displacement by Betamax and VHS
- 4.9 =N-1700 Long Player Video Recorder
- 4.10 Laser-Cut Technology for Video Heads
- 4.11 Future Replacements of VHS