JPH0223941B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention uses PCM (pulse code modulation) to process information signals such as audio signals and image signals.
This invention relates to a digital disc player device that extracts and demodulates the digitally encoded signal from a disc on which the digitally encoded signal is recorded, and in particular corrects warpage of the disc and prevents resonance to perform good demodulation. It relates to something that is made to look like this.

Recently, with the aim of recording and reproducing information signals such as audio signals and image signals with as high fidelity and high density as possible, a digitally encoded signal obtained by converting the information signal into PCM is directly recorded on a disk, and during playback. Digital disc player devices have been developed that extract and demodulate digitally encoded signals from this disc. As well-known recording and reproducing methods for this digital disc player device, there are an optical method and a capacitance method.

For example, in a digital disk player using an optical system, the track pitch of the disk is usually formed to have a width of several microns in order to increase the recording density. Therefore, unless the beam spot of the light irradiated onto the disk surface from the pickup is narrowed, the S/N ratio will deteriorate. On the other hand, the distance between the pick-up and the disk is regulated, and since the light is focused at that distance, the depth of focus must be shallow, so the distance between the pick-up and the disk must be precisely defined with high precision. For this reason, conventionally, a focusing servo or the like is used to appropriately correct even if there is a slight variation in the distance between the pickup and the disk.

However, if the distortion of the disk during disk molding or the warpage of the disk due to the difference in thermal expansion coefficient between the resin and plated metal that make up the disk is large enough to exceed the correction range of the servo system, a good reproduction signal may not be obtained. The problem is that it becomes impossible to do so.

In addition, the disk is driven to rotate by having its center portion sandwiched between a turntable and a predetermined clamper, but as is well known, it generates a unique vibration when rotating, and generally has a frequency of 90 Hz. It will have a large resonance point nearby. Therefore, when external vibrations or shocks are applied to the player device, the disk vibrates significantly at a frequency near the resonance point, and the amount of vibration often exceeds the correction range of the focusing servo system. This makes it impossible to obtain a good reproduced signal.

The present invention has been made in consideration of the above circumstances, and provides an extremely good digital disc player device that has a simple configuration, easily prevents the adverse effects of disc warping and resonance, and can obtain a good reproduction signal. The purpose is to

Hereinafter, an embodiment in which the present invention is applied to an optical digital audio disc player will be described in detail with reference to the drawings. In FIG. 1, reference numeral 11 is a turntable made of a light-transmitting material such as glass or transparent acrylic and formed into a substantially disk shape. A through hole 111 is formed in the center of the turntable 11, and a substantially cylindrical support member 1 is disposed within this through hole 111.
2 is fitted. Then, the support member 12
A flange portion 121 is formed at a predetermined position on the circumferential surface of. This flange portion 121 is in contact with the lower surface of the turntable 11 in the figure to support the turntable 11. Further, the support member 12
A through hole 122 is formed in the center of the supporting member 12 in the vertical direction.
A shaft 13 is fitted inside.

Here, the shaft 13 is rotatably supported in a cabinet (not shown) of the digital audio disc player, and is configured to transmit the rotational driving force of a motor (not shown). Further, a disk 14 is placed on the turntable 11. This disk 14
For example, the aluminum reflective film is coated with a protective lacquer and formed into a disc shape with a diameter of 12 cm, with a through hole 1 formed in the center.
The support member 12 is inserted through the support member 41 and placed on the turntable 11. On one side (lower side in the figure) of the disk 14, a digitally encoded signal obtained by converting an audio signal into PCM is directly recorded in the form of pit rows of uneven on/off and different intervals.

Further, a pickup 15 is provided on the lower surface of the turntable 11 in the figure at a position facing the signal recording surface of the disk 14. The pickup 15 includes a pickup section 151 for irradiating and receiving a laser beam, and is supported so as to be movable in the radial direction of the disk 14.
The pickup 15 is moved from the inner circumference to the outer circumference of the disk 14 during playback, and the rotation speed of the disk 14 is about 500 to 200.
It is a constant linear velocity (CLV) type with [times/minute].

Here, when a playback operator (not shown) installed in the cabinet is operated, the rotational force of the motor is transmitted to the shaft 13, and the disk 14 is rotationally driven via the support member 12 and the turntable 11. A laser beam is irradiated from the pickup section 151 of the pickup 15 to the signal recording surface of the disk 14 via the turntable 11. Then, this laser beam hits the signal recording surface of the disk 14 and is reflected, and the reflected beam is received by the pickup section 151 via the turntable 11. For this reason, the pickup 15 detects the intensity and temporal length of the light and outputs an electrical signal corresponding to the intensity, and the digitally encoded signal recorded on the disk 14 is extracted therefrom.

Here, the first
A substantially disc-shaped stabilizer 16 having a diameter substantially equal to that of the turntable 11 is provided in the upper part of the figure. This stabilizer 16 is used to clamp the disc 14 from the inner circumference to the outer circumference between the turntable 11, correct warpage of the disc 14, and prevent resonance.

That is, the stabilizer 16 has a precisely flat surface that contacts the disk 14 (lower surface in the figure), and a recess into which the support member 12 is fitted in the portion that faces the support member 12. 161 is formed. A protrusion 162 is formed on the upper surface of the stabilizer 16 in the figure, which faces the recess 161 . This protrusion 16
A mounting member 17 is rotatably connected to the upper part of FIG. That is, when viewed from the mounting member 17 side, the stabilizer 16 can rotate in the same direction as the turntable 11. This mounting member 17 includes a substantially rod-shaped connecting member 1.
8 are rotatably connected. The other end of the connecting member 18 is rotatably connected to a fixing member 19 projecting from the cabinet.

In the normal state, the stabilizer 16 is installed at a position away from the turntable 11, as shown in FIG. In this situation,
Place the disk 14 on the turntable 11,
By lowering the stabilizer 16 downward in the drawing, the disc 14 is interposed between the turntable 11 and the stabilizer 16, as shown in FIG. Therefore, the warp of the disk 14 is corrected in terms of the accuracy of the oblique plane of the lower surface in the figure of the stabilizer 16, and when rotating, the stabilizer 16 suppresses the natural vibration and prevents resonance.

Therefore, since the distance between the pickup section 151 of the pickup 15 and the signal recording surface of the disk 14 is approximately equal everywhere, good reproduction can be achieved.

FIGS. 3 and 4 each show a modification of the stabilizer 16 described above. First, in the one shown in FIG. 3, a first cylindrical member 20 with a small diameter is
loosely fits into the center of the second cylindrical member 21 with a large diameter,
The two are connected and integrated. According to such a configuration, the first cylindrical member 20 can hold down the inner circumference of the disk 14, and the second cylindrical member 21 can hold down the outer circumference of the disk 14, so that, for example, the entire disk 14 can be held down. Effective for correcting warpage, etc.

Moreover, the one shown in FIG. 4 has the same purpose as the one shown in FIG.

Furthermore, it is also possible to press not only the inner and outer circumferential parts of the disk 14 but also the intermediate part thereof.
In short, a plurality of locations on different radii of the disk 14 may be pressed.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be implemented with various modifications without departing from the gist thereof.

Therefore, as described in detail above, according to the present invention, there is provided an extremely good digital disc player device which has a simple configuration and can easily prevent the adverse effects of disc warpage and resonance and obtain a good reproduction signal. can be provided.

[Brief explanation of drawings]

FIG. 1 is a side sectional view showing an embodiment of a digital disc player device according to the present invention, FIG. 2 is an explanatory diagram of the operation of the same embodiment, and FIGS. 3 and 4 are modifications of the stabilizer of the same embodiment, respectively. It is a top view and a side sectional view which show an example. 11... Turntable, 12... Support member,
13... shaft, 14... disk, 15... pick-up, 16... stabilizer, 17... mounting member, 18... connecting member, 19... fixing member, 2
0...First cylindrical member, 21... Second cylindrical member.

Claims (1)

[Claims] 1. A digital disc player device that extracts and demodulates a digitally encoded signal formed by converting an information signal into PCM from a disc on which the digitally encoded signal is recorded, on which the disc is mounted and the disc mounting surface is flat. The disc is sandwiched between a turntable formed in the shape of a shape, and the disk placed on the turntable, and is pressed against the disk placement surface of the turntable. A digital disc player comprising: a stabilizer that contacts an inner circumferential portion thereof and a plurality of locations extending from the inner circumferential portion toward an outer circumferential direction of the disc.