JPH0617216Y2 - Drive motor controller for CD player - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a drive motor control device for a CD player, and more particularly, it automatically determines the size of a CD and sets the servo gain of the drive motor to an appropriate value. The present invention relates to a drive motor control device for a CD player.

[Prior Art] In addition to the conventional 12 cm CD, a so-called single CD having a diameter of 8 cm has been released in recent years. Therefore, on the disk tray of the CD player, 8 cmC which is concentric with the positioning part of 12 cmCD
A D mounting recess or tray is provided to support the 8 cm CD. Further, there is also known a CD player in which the servo gain of the drive motor is switched by a manual switch in order to cope with the difference in inertial mass between 12 cmCD and 8 cmCD.

[Problems to be Solved by the Invention] In the above-described conventional drive motor control device for a CD player, the one having a constant servo gain is a 12 cm CD or 8 cm.
Since there is a significant difference in the rotational inertia from the cmCD, the linear CD has a constant linear velocity, and a high level of performance is required for the rotational control. Therefore, it is difficult to deal with both. Therefore, for example, a device that can reproduce a 12 cm CD without any problem may cause an error in reading a signal of 8 cm CD, and in the case where sound skips or is serious, reproduction cannot be performed at all. On the other hand, a CD player provided with a servo gain switching switch does not cause the above-mentioned problems, but the operation of the switching switch is troublesome, and the ease of operation, which is one of the features of the CD, is significantly diminished.

Therefore, there arises a technical problem to be solved in order to appropriately change the servo gain of the drive motor to improve the stability during reproduction and to automatically perform the switching operation to improve the operability. Therefore, the present invention aims to solve the problems.

[Means for Solving the Problems] This invention has been proposed in order to achieve the above-mentioned object, and in a CD player, after the CD is loaded, the drive motor is rotated at a constant speed, and then the reverse rotation is performed. A controller that applies a constant torque in the direction, measures the time for the number of rotations of the CD to drop to a predetermined value, determines the size of the CD based on the time, and sets the servo gain of the drive motor to an appropriate value. A drive motor control device for a CD player is provided.

[Operation] In the present invention, the microprocessor for controlling the CD player is provided with the control unit for detecting the size of the CD. When the CD is loaded, the control unit rotates the CD at a constant speed, and thereafter, applies a constant torque in the reverse rotation direction to the drive motor so as to forcibly reduce the rotation speed of the CD. Then, the time required to reduce the rotation speed to a predetermined value is measured, and the CD is 12 cm CD or 8 cm depending on the time.
Determine if it is a CD. That is, since the rotational inertias of the 12 cm CD and the 8 cm CD are different by several times, there is no possibility of causing a large difference in the time required for the rotational speed to decrease to the predetermined number of rotations and erroneous size determination. After the discrimination, the rotation of the drive motor is controlled by the appropriate servo gain for each of 12 cm CD and 8 cm CD, so that the signal reading error caused by the improper servo gain does not occur, and the reproduction failure or the reproduction is impossible. It never becomes. Further, the discrimination is automatically and instantly performed, and a manual operation such as a switching switch is not necessary, so that the promptness and easiness of the operation are not hindered.

[Embodiment] An embodiment of the present invention will be described below in detail with reference to the attached drawings. For convenience of description, technical matters that are conventionally known will be described at the same time. FIG. 1 shows a state in which the disc tray (2) of the CD player (1) is "open". The central portion of the disk tray (2) is a recess having a diameter larger than 12 cm CD.
(3) is formed, and when the 12 cm CD is placed in the recess (3) and the disk tray (2) is closed, the 12 cm CD is set on the spindle of the drive motor (not shown). A small tray (4) for 8 cm CD is arranged in the front-rear direction of the central portion of the recess (3), and 8 cmC placed on the small tray (4)
D is positioned so as to be positioned concentrically with the 12 cm CD, and is set on the spindle of the drive motor in the same manner as the 12 cm CD by closing the disk tray (2). When a 12 cm or 8 cm CD is set, the drive motor control device (5) built into the CD player (1) immediately starts the rotation of the drive motor in response to a command from a microprocessor (not shown). The size of the rotating CD is detected by the procedure described later, and the CD is reproduced with an appropriate servo gain or waits for another command.

The size detection procedure will be described with reference to the flowchart of FIG. First, put the CD on a disc tray (2)
Then, the disk tray (2) is closed and the program of the drive motor controller is started. Immediately after the CD is set on the spindle of the drive motor, the drive motor starts rotating (step 500), for example. When the number of rotations of the CD reaches the set value, the drive voltage is controlled so that the torque in the reverse rotation direction is applied to the drive motor (step). In that case, the rotation speed of the drive motor is rapidly reduced, and it is confirmed that the rotation speed has reached a predetermined rotation speed set in advance, and the time (T) required to reach the rotation speed is measured (step). At this time, since the rotational inertia is different depending on the size of the CD set in the drive motor, the time (T) is significantly different between 12 cmCD and 8 cmCD. Then, the size detection judgment branch value (A) of the time is determined from the number of revolutions in the step, the voltage control amount in the step, and the rotational inertia of the CD of 12 cm and 8 cm, and is input to the microprocessor in advance. Therefore, the size of the rotating CD is judged (step). Then, the microprocessor controls the servo gain so that the servo gain becomes appropriate for the determined size, finishes the size detection (step or), and shifts to signal reading as steady rotation. Further, since the servo gains are set to be suitable for the rotational inertias of 12 cmCD and 8 cmCD respectively, a signal reading error due to an excessive or insufficient control amount will not occur.

It should be noted that the present invention can be modified in various ways without departing from the spirit of the present invention, and it goes without saying that the present invention covers the modified version.

[Effects of the Invention] As described in detail in the above-mentioned one embodiment, this invention applies a constant torque in the reverse rotation direction to the drive motor after the CD is rotated to reach a certain speed after the CD is loaded. And C
The time required for the rotation speed of D to decrease to a predetermined value is measured by the microprocessor connected to the drive motor control device.
At this time, since there is a significant difference in the rotational inertia between the 12 cm CD and the 8 cm CD, the rotating CD is 12 cm from the measurement time.
It is easy to judge whether it is a CD or an 8 cm CD, and based on this judgment, the drive motor control unit is operated so that the microprocessor has a proper servo gain for the rotating 12 cm CD or 8 cm CD. . After that, the reproduction of the CD is started, but the work of discriminating the size is completed in an extremely short time, and the time required from the loading of the CD to the start of the reproduction is almost the same as that of the conventional type.
Then, since the drive motor rotates with an appropriate servo gain for each of 12 cm CD and 8 cm CD, the rotation control is stabilized, an error is prevented from occurring in the signal reading of the CD, and the discrimination work is automatically performed. ,
It is possible to contribute to stabilization of the performance of the CD player and improvement of operability without requiring any complicated operation such as switch switching.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 1 is a partially cutaway perspective view of a CD player, and FIG. 2 is a flow chart of a drive motor controller. (1) …… CD player, (2) …… Disk tray (4) …… Small tray (5) …… Drive motor controller

Claims (1)

[Scope of utility model registration request] 1. In a CD player, after a CD is loaded, a drive motor is rotated at a constant speed, and after that, a constant torque is applied in the reverse rotation direction to measure the time for the number of rotations of the CD to fall to a predetermined value. Then, a drive motor control device for a CD player, characterized in that a control unit is provided for discriminating the size of the CD according to the time and for making the servo gain of the drive motor an appropriate value.