Blue Ray drive explained : mechanical mechanisms

Hi,

Here we go; I will try to give you information to understand how the blue ray drive works!

First we will see the mechanical mechanisms to handle the disc in order to read it.
Then we will analyze the controller board which does the entire job!

1) The mechanical parts

Well the first thing to say is that an optical drive is quite a complex stuff and it integrates very complex mechanisms and technologies. And SONY did quite complicated stuffs for little functions, for example the insertion trap, but we’ll see that later!

Lets resume what is the function desired.

All this drive has to do is to grab the disc, drop it on the spindle motor, read the data by rotating the disc and eject the disc back out. And that’s it!



On this picture we can see:
- The disc slot is where you put the disc to insert it, and it is where you get it back once ejected.
- When you place the disc inside the disc slot for some millimeters, the insertion sensor detects the intrusion which launches the insertion process.
- The insertion process will place the disc onto the rotation motor. As the rotation speed can get quite high, the disc has to be mechanically fixed to the rotation motor. The white magnetic spindle does this thanks to it magnet which will stick the disc on the rotation motor.

The next picture shows the bottom side of the drive.



There you find the controller board which is called “daughter board” as it is attached to the main board of the PS3.

And the other very important stuff is the mechanical transmission part, which looks like a big V thing, which goal is to link mechanically two big plastic parts inside the drive! When one is going up the other is going down, and the other way.

Here are these parts on an open view of the drive.



As I said the disc is grabbed at the entrance of the drive. This is done by the disc insertion grabbers that take the disc in, as they are in rotation. As the disc gets in, these wheels are pushed to the sides of the drive, always keeping a pressure on the disc.

As the disc reaches its final position over the rotation motor, several things append.

The rotation motor (which is on the tray) is below the disc, as the disc gets in the whole tray goes high, reaches the disc and pushes the disc on the magnetic spindle to get it mechanically maintained. In the same time the disc insertion grabbers are arriving at the end of their translation and they free the disc to let him get catched by the rotation motor spindle.

Now the disk is free to rotate thanks to the rotation motor.

This last process it done by a really complex mechanical mechanism which involves many parts.

These last actions also drop the insertion trap with the insertion trap control; a mechanism locks it closed, in order to not insert another disc. This is done by the insertion trap lockers.

Now let's see the insertion parts.



The major parts are the two lateral elements.

But before, let's talk about the complex mechanism that SONY made, just to shut and lock the insertion trap!

When the disk is inserted, the right lateral part moves up, which frees the insertion trap control, which has a spring to place it when the right lateral part leaves. While the insertion process is running, and that the insertion motor is turning, the rotation motor is also used to rotate the white gears at the bottom which makes the bottom left polley turn, which uses the driving belt, activating the bottom right polley to turn, which pulls the big bottom white part to the right, raising the two insertion trap lockers. During the ejection, these elements are removed back to their original position using the spring.

Isn’t that complex just to lock the trap??!!

Let’s go back to the insertion.

As you can see on the picture, the insertion motor drives some more gears on the bottom left. And the main point, is that it drives the trammel on the left lateral part. This pulls this part down, which pulls the right lateral part up (thanks to the big V part). As these parts move, it brings up the tray.

The parts that we can see on the left of the picture are placed above the disc and drive. These parts have lugs that go into plastic guides that we can see on the two lateral parts. So when the two lateral parts move, the lugs are forced to follow a path that make the above part move in a particular way. These parts are used in the handling of the disc during the insertion.

So now for the ejection it is the other way.

The ejection motor pushes with the gears the left lateral part up, which pushes the right lateral part down. The tray is going down which frees the disc that is catched by the grabbers that eject it out of the drive. As the right lateral part is going down it pushes back the trap insertion control part which opens the trap to let the disc go out, which has previously been unlocked with the polleys thing.




Well, I surely forgot some details but it gives you an idea on how this is quite complex and that each part has a dedicated function. So if you mess up with one when you open the drive, it surely will have mechanical problems when you use it again.

If you have to get in the drive, use tutorials, get a precise look at what you touch (how, when, where) and put it back the other way in the same manner!




Well next time we’ll focus on the daughter board!

Coming soon….

(I'm not happy with my english on this one, feel free to point out corrections !)