Process for stopping a rotating disc-shaped record medium

Details Process for stopping a rotating disc-shaped record medium Process for stopping a rotating disc-shaped record medium

1992-12-03

1995-09-05

Tupper, Robert S.

Dynamic information storage or retrieval

Dynamic mechanism subsystem

Specific detail of storage medium support or motion production

369231, 318257, G11B 2300, G11B 1922, H02P 310

Patent

active

054485495

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The invention relates to a process for stopping of a rotating, record-shaped information medium.
CD-player or video record player are for instance equipped with a loading--and unloading device into which the information medium, a compact disc or a video record, is manually inserted or out of which the same can be taken by hand. After inserting the record, the record is automatically brought into the reproduction position. By means of a so-called STOP-key the user of the CD-player can at any time interrupt the reproduction of a record. The record will be stopped and moved automatically into the unloading position so that the user can remove the record from the loading device for instance in order to be able to insert a different record.
Before, however, the record is brought from the reproducing position into the unloading position, the same should be braked possibly to full-stop by the motor of the record drive in order to avoid damage of its sensitive surface during the unloading process.
The rotational speed of a record is not constant, because in a CD-player the system concerned is, contrary to a CAV (constant-angular-velocity) system which keeps the angular velocity constant, a CLV (constant-linear-velocity) system which keeps the linear velocity constant.
It can therefore absolutely be the case that the record still rotates during the unloading process, either in the reproducing direction or even in the reverse direction, depending on the braking action by the motor, i.e., not enough or too much. Also because the mass and the diameter are different from record to record and because the small mini-CD exists besides, it may occur that the record is still rotating during the unloading process. As mentioned already the sensitive surface of a record, which still rotates during the automatic unloading process, can easily be damaged.
In order to make certain that the record really is stopped at the beginning of the unloading process, there should be provided a short waiting time between the braking of the record and the unloading process as a time clearance during which the record can run down. This measure has, however, the draw-back that the unloading process will be delayed.
It is therefore the object of the invention to provide a process for the stopping of a rotating, record-shaped information medium such that the rotating information medium will be fast and reliably braked down to total stop for unloading.


SUMMARY OF THE INVENTION

The invention solves the above object by the following process steps presettable value +N, the time T is measured until the rotational speed of the information medium reaches the opposite value -N, value -N, the polarity of the first braking pulse is reversed and discontinued.
A second development of the invention provides for repeating the process steps a) to c) several times and to form the mean value T.sub.M, using the measured times T, which pass each time at reversal of the rotational speed, and to dimension the duration of the last braking pulse to T.sub.M /2.
By this measure the duration of the last braking pulse, which brakes the information medium to a complete stop, will be determined more exactly than with the first development according to the invention.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block circuit diagram of an arrangement for realizing the process according to the invention
FIG. 2 is a pulse diagram for explaining the invention


DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows the drive motor M, which drives a compact-disc CD. A revolution counter DM, which measures the rotational speed of the record CD, is connected with the input of a detector D, whose both outputs are connected with both inputs of a control circuit ST. The output of the control circuit ST is connected with the input of a braking pulse generator BG, whose output is connected with the drive motor M.
For stopping the record CD the braking pulse generator BG supplies a first braking pulse B1 (FIG. 2) to the drive motor M, whereby th

REFERENCES:
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patent: 4388713 (1983-06-01), Tatsuguchi
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patent: 4439849 (1984-03-01), Nabeshima
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patent: 4653040 (1987-03-01), Senso
patent: 4710825 (1987-12-01), Okita et al.
patent: 4779260 (1988-10-01), Kaneko et al.
patent: 5050145 (1991-09-01), Yoshida

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