Umatic

THE CASSETTE

Find a need and fill it is an axiom often used to explain the success of a product. When Sony developed a new market with the portable reel-to-reel video recorders one thing became obvious. Television broadcasting was wide open for smaller, portable news gathering video recorders. On the spot reporting became the hot new sales tool for the networks and their affiliates to show sponsors that were on the cutting edge when it came to the news, sports and special events. One other thing was obvious too. As good as the Sony reel-to-reel video recorders were they were not that user friendly. Threading the tape around the video drum and throughout the drive components was awkward and time consuming. A better way was needed and Sony decided they were going to make it. U-matic was in the works.

Sony gained an immediate upper hand and the "first mover advantage" in the compact and mobile broadcast marketplace. The smaller size and portability of their reel-to-reel recorders made them easy to carry from event to event. It was good but it could be made better. What was needed was the self-contained cartridge that was becoming the standard in the professional radio broadcast market. When Sony introduced the first practical cartridge video recorder, the U-matic, things really began to heat up (PLATE 1). For video there was virtually no competition and they ended up owning the new technology outright, in particular the horizontal scanning method. If any manufacturer wanted to participate in this new cassette technology (and there were many) they had to license this system from Sony. Because the fully enclosed cassette design was such a hit it made Sony the leader in the professional broadcast marketplace. Up until then they had introduced compact transistor radios, audio tape recorders and televisions mainly to the public, but now they owned a new standard for video recording. In the photo above we see on the left a Sony engineer demonstrating an early version of the U-matic recorder. In front and center is a semi-transparent cassette showing how the reels inside were nested together to save space. The recorder pictured is one of the later designs that sported all the bells and whistles found on the most expensive studio models.
Click on the photo (PLATE 2) and we can see the interior of one of the U-matics so we can examine how Sony made cassette recording possible. If you ever looked inside an early Betamax or explored my Website you will notice some very familiar territory here. We are looking down into the top with the cover removed. In the upper left corner is the main drive motor. In the center is the video drum and tape threading ring assemblies. Click on the photo again (PLATE 3) and here we see the overall tape handling assembly. Referring to the photo we see at the bottom center are the supply and take up reels. If your familiar with the Betamax you will notice that they are reversed in the U-matic. The tape travels in the opposite direction to the Beta format. Also notice the long extracting arm that pulls the tape into the threading ring. The tension arm is also on the opposite side from the Betamax. Click the photo again (PLATE 4) and it shows the 3/4 inch tape being extracted from the cassette, it is just beginning to start wrapping the tape around the video drum. It is also on its way to being positioned onto the guides of the threading ring. It does all this automatically and no participation is required by the operator. A tape roller guide that rotates the tape around the path and the pinch poller are indicated. Click for the next picture (PLATE 5) and it shows the tape completely threaded into the tape path. The various guides and drive components are identified. Click the picture again (PLATE 6) and the cassette door (in this case it is the black plastic at the top over the opening) is lifted up. The tape is shown being drawn out of the cassetteopening. Click to the next picture (PLATE 7) and it shows on the left in this split picture one of the video heads that is mounted on the disk assembly (illustrated upside down). On the right in this picture is the supply reel. Notice the copper colored band wrapped around it. It has a thin strip of felt glued to it that rides against the exterior surface of the reel. The band attaches at one end to a stationary peg and the other end is mounted to an arm that is free to move in relation to the tension being place on it by the video tape (as it feeds out of the cassette). This method maintains a regulated tension as the tapes moves through the tape path during play and record. The amount of tension can be regulated by a spring that pulls against the arm (not shown). Click on the photo (PLATE 8). Here we see four photos of the inside of the U-matic. The upper left is a photocell assembly that senses the end and beginning of the tape. A clear leader of film at each end lets a tiny light shine through it when it passes by which triggers the stop mode when the tape reaches the end or the beginning. The lesion arm can also be seen. In the upper right is the photocell arrangement from a different angle. In this U-matic only one photocell was used, some had two. The lower left photo is a close up of the pinch roller, capstan and the audio/control track head. The photo at the lower right is of the video drum.The video head, that travels in a longitudinal slot is indicated. All U-matics had two or more. Click the photo (PLATE 9) and here is a size comparison of drums for the Betamax and U-matic formats. The smaller upper drum is Beta. Beta also uses a 1/2 inch wide tape, U-matic is 3/4 inch. Click the photo again (PLATE 10) and here is a split shot of two types of switching sensors. These are used to regulate the speed of the drum and to start the recorded video at the top of the screen at the proper time. The one on the left uses a metal blade to pass over a magnetic pick up and the one on the right uses a coil that senses a tiny magnet passing over it. (It is under the copper colored disk.) The next photo (PLATE 11) is of the underside. This is the belt arrangement that drives the threading ring, capstan, drum and tape reels. The (early) Betamax also used a single large motor to drive all the moving components during recording and playback. threading and unthreading which used separate motors. Click on the photo (PLATE 12) and notice the large electromagnet (center) positioned under the drum. This is a rotation brake, sort of like a motor in reverse. It was energized to adjust the rotational speed of the video head disk so it could precisely start every video frame on time. Since the video heads had to be kept turning at a constant speed Sony spun them slightly faster than was required. The brake was used to slow them down slightly to create the correct turning speed. The belt that was driving the head disk was designed to allow for some slipping so the breaking action could take place. Later this system was abandoned and the video drum would have its own motor.

The design of the U-matic system was developed by Sony and much of it was covered by international patents. Many manufacturers other than Sony entered this new recording field and used the design. Under Japanese laws they were able to license this technology by paying royalties. This is something that was good for Sony but probably didn't make them real popular with some of the other unit ma nufgacturers. This disapproval would show up later when Sony introduced home video recording and this will be covered in a later discussion. U-matic continued in popularity for a good while because of its overall acceptance and its ability to faithfully reproduce the NTSC broadcast standard. The next photo (PLATE 13) shows some of the models and the the logos used, all were required to use the "U" within their name. The next photo (PLATE 14) shows some Sony units. And the last photo in this set (PLATE 15) shows a couple of models that were made that had tuners, allowing them to receive broadcast television reception. To got to the next panel "The First Home Unit" click here.