JPS5810194Y2 - optical recording and reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for optically recording or reproducing by projecting a recording or reproducing light beam from an optical device onto a disc-shaped recording medium.

Devices for recording or reproducing video signals using lasers have already been developed.

FIG. 1 is a schematic plan view showing a conventional video disk 1 for optical reproduction.This disk 1 has a spiral track form as shown by a track 2, and a composite video signal (for example, NT
SC color television signal) is recorded.

As shown in Fig. 2, the composite video signal has a vertical blanking period TB for each field of the television screen, one field for half a turn of the disk 10, and one frame for one turn of the disk 1. As a result, a vertical blanking period portion 3.4 appears in the hatched area on the video disc 1.

The vertical blanking period portions 3 and 4 are equivalent pulse periods T0 of 3H (here, H is one horizontal scanning time of 63.5 μs, for example), vertical synchronization pulse periods T2 of 3H, and equivalent pulse periods T3 and 12H of 3H. This corresponds to a vertical blanking period TB consisting of a horizontal synchronizing pulse period T4 and a horizontal synchronizing pulse period T4, in which the above-mentioned synchronizing pulse signal is recorded.

Usually, a composite video signal is FM modulated and then recorded in pits (grooves) as shown in FIG.

That is, an information signal is recorded by projecting a modulated light beam onto a transparent resin layer 5, which is a recording medium made of vinyl chloride or the like, and forming pits 6 corresponding to FM modulated waves in a predetermined track form.

For example, the width of the pit is approximately 1μ, the depth of the pit is approximately ±λ (here, λ is the wavelength of the laser beam), and the length of the pit differs between the inside and outside of the disc, and the frequency of the FM modulated wave For example, it is 1.5 to 6μ.

T is a light reflecting surface provided by depositing or plating metal after the pits are formed, and is essential for reading recorded signals using reflection of light.

8 is a protective film that protects the reflective surface 7.

FIG. 4 shows a device for optically reading signals from the disk 1 as described above, and this device engages the center holding hole 10 of the disk 1 with the boss of the turntable 9, thereby aligning the center of the disk with the center of the disk. The disk 1 is made to coincide with the center of rotation of the chiffle, the disk 1 is tightened and fixed by a clamper 11, and the disk 1 fixed to a turntable 9 is rotated by a motor 2.

Reference numeral 13 denotes an optical device that projects a reproducing light beam 14 onto the disc 1 and detects its reflected light.

The optical device 13 is adapted to be fed in the radial direction of the disk 1, and is equipped with an automatic focusing mechanism and an automatic tracking mechanism (not shown) as shown in FIG.

The automatic focusing mechanism shown in FIG. 5 couples a focusing objective lens 16 to a moving coil 17.
is arranged in a permanent magnet 18, and by passing a current through the moving coil 11, the objective lens 16, which is integrated with the coil, is displaced, and the light beam 14 is focused on the scanning surface of the disk 1.

Although not shown, a device for detecting the distance between the scanning surface of the disk 1 and the objective lens 16 and a circuit for forming a signal for controlling the moving coil 17 based on the distance detection output are of course provided.

When reading the information signal from the disk 1, as is clear from FIGS. 3 and 4, the light beam 14 is projected onto the disk from the bottom surface 1a side of the disk 1, and the light beam 14 is projected onto the disk from the bottom surface 1b side of the disk 1.
The pits 6 are read by optically scanning the reflecting surface 1 that substantially coincides with the .

When the light beam 14 scans a track on which pits 6 are formed, the reflected light 15 will be reflected depending on the presence or absence of pits.
The intensity of the information changes and the information pits can be read optically.

By the way, the disk 1 includes a relatively strong thick disk as shown in FIG. 6 and a relatively flexible thin disk as shown in FIG.

Now, if the thin disk 1 is mounted on a device that is set so that the light beam 14 projected from the optical device 13 is focused on the scanning surface (near the top surface) of the thick disk 1 shown in FIG. As shown in the figure, the light beam is no longer focused on the scanning surface (near the top surface) of the disk.

Therefore, generally the optical device 13 is moved downward, or
An automatic focusing mechanism shown in FIG. 5 provided in the optical device 13 displaces the objective lens 16 to focus the light beam on the scanning surface.

However, this method of moving the optical device 13 has the drawbacks that the moving mechanism becomes complicated and the operation becomes troublesome.

Furthermore, in the method of using the automatic focusing mechanism, for example, when playing with a thick disk as shown in FIG. 6, the current of the moving coil 17 is set to be zero at the neutral position (just focus position) of the disk. For example, during playback using a thin disk as shown in FIG. 7, a direct current constantly flows through the moving coil 17, which deteriorates the linearity of the input/output characteristics and makes it impossible to accurately control focus by following vertical fluctuations of the disk. There are also disadvantages in that the moving coil 17 generates heat, and further disadvantages in that depending on the extent of the difference in thickness, it may not be possible to correct it completely.

Therefore, an object of the present invention is to provide an optical recording/reproducing apparatus that solves the above-mentioned drawbacks.

In order to achieve the above object, an optical recording/reproducing device according to the present invention includes a first disc-shaped recording medium mounting base, a first diameter and a predetermined diameter formed at the center of the first disc-shaped recording medium mounting base. a first boss portion having a height of a turntable having a second boss portion having a second diameter smaller than the first diameter; When used for optical recording or reproduction, the first boss part is fitted into the central engagement hole, and the first disc-shaped recording medium is placed on the first disc-shaped recording medium mounting table. When optically recording or reproducing using a second disc-shaped recording medium placed on the disc and having a second thickness smaller than the first thickness by the predetermined height, the central The second boss portion is fitted into the engagement hole, and the second disc-shaped recording medium is placed on the second disc-shaped recording medium mounting table. .

With the above-described configuration, the distance between the optical device and the light beam scanning surface will be approximately constant no matter what thickness a disc-shaped recording medium (for example, a video disc) is loaded.

Next, embodiments of the present invention will be described with reference to the drawings.

However, parts common to those in FIGS. 1 to 7 are designated by the same reference numerals and their explanations will be omitted.

8 and 9 show a part of a video disc player according to a first embodiment of the present invention.

This video disc player is constructed so that both a relatively thick first disc 21 shown in FIG. 8 and a relatively thin second disc 22 shown in FIG. 9 can be used.

One first disk 21 is formed to have a thickness gt□ and has an engagement hole 23 with a diameter D1 in the center thereof.

The second disc 22 has a thickness t2Vc and has a retaining hole 24 at its center D2.

As is clear from the drawing, 1 > 1 and D >
It has become D22.

Further, each of the disks 21 and 22 is formed as shown in FIG. 3, and the vicinity of the upper surface 21a, 22a of each disk is an optical scanning surface.

The turntable 9 coupled to the rotating shaft 25 has a first
A disk mounting table 26 is provided without a housing, and a cylindrical first boss portion 27 is provided at the center of the first disk mounting table 26.

As is clear from FIG. 8, the first disk mounting table 26 is not formed to place the entire surface of the disk.
It is formed so that only a portion of the disk is placed thereon.

The first boss portion 27 of the housing is formed to have a first diameter that fits into the engagement hole 23 having a diameter D1 of the disk 21, and its height gh is equal to the thickness tl of the disk 21 and the disk 22.
The difference between the thickness and the thickness t2, that is, h=t□−t2.

On the upper surface of the first boss portion 27, there is a second disk mounting table 28 for placing the second disk and a second boss portion 29.
is provided.

The second boss portion 29 is shaped to have a second diameter Jli3 to fit into the central engagement hole 24 of the disk 22 having a diameter D2, as is apparent from FIG.

A clamper fixing screw portion 30 is provided on the upper surface of the second boss portion 29.
is provided, and the clamper 11 is screwed thereto.

When loading the first disc 21 into the player configured as described above and putting it into the playback state, first, the clamper 11 is removed and the first disc 21 is inserted into the lower first boss portion 27 having a large diameter. Engage the retaining hole 23 of the disk with a diameter D□, and then,
It is fixed with a clamper 11 as shown in FIG.

As a result, the clamper 11 and the first disk mounting table 26
The first disk 21 is held between the two and rotates as the turntable 9 rotates.

Since the height of the first disk mounting table 26 is set to be a predetermined height with respect to the optical device 13, if a disk 21 with a predetermined thickness gt□ is mounted, the upper surface 21a of the disk 21 will be The height becomes a desired height from the optical device 13, and the light beam 14 comes to be focused on the pit forming surface (scanning surface) near the top surface of the disk 21 configured as shown in FIG.

If the disk 21 does not move up and down, it will be in just focus with no current flowing through the moving coil 17 shown in FIG.

When installing the second disc 22 and entering the playback state,
The upper second boss portion 29 with a smaller diameter is engaged with the engagement hole 24 of the second disk having a diameter D2, and then the clamper 1
Tighten and fix with step 1.

Thereby, the disk 22 is held between the clamper 11 and the second disk mounting table 28.

The height of the upper surface 22a of the disk 22 from the first disk mounting base 26 when the disk 22 is held is:
The height gh of the first boss portion 27 and the thickness t2 of the second disk
and matches the thickness t□ of the first disk 21.

Therefore, the distance between the optical device 13 and the top surface 22a of the disk 22 is equal to the distance between the optical device 13 and the top surface 21a of the disk 21 in FIG.
The light beam 14 is focused near point a, making it possible to perform optical reproduction in good conditions.

That is, when the disk 22 is not moving up and down, reproduction can be performed with focus control such that no current flows through the moving coil 17 shown in FIG. 5.

Note that the pit 6 formation surface (scanning surface) and the disk 21. 2
However, since the reflective surface 7 and the protective film 8 are extremely thin, the scanning surface and the upper surfaces 21a and 22a substantially coincide with each other.

If the protective film 8 or the like is thick, the thickness of the protective film should not be changed depending on the type of disk.

As a result, the relationship between the lower surface 31 of the clamper and the scanning surface becomes constant regardless of the type of disk, and the distance between the optical device 13 and the scanning surface also becomes constant.

Or a protective film 8 and a reflective surface 7 are provided on the part that comes into contact with the clamper 11.
Alternatively, the upper surface of the transparent resin layer 5 may be pressed directly without being provided.

As a result, the heights of the scanning surface where the pits are formed and the lower surface 31 of the clamper match regardless of the thickness of the disk.

As can be understood from the above explanation, this player allows optical reproduction to be performed in the best possible condition regardless of changes in the thickness of the disc.

FIG. 10 shows a disc recording/reproducing apparatus according to a second embodiment.

In this recording and reproducing apparatus, an optical device 13 is arranged above a disk 41, and a recording or reproducing light beam 14 is projected onto an upper surface 41a of the disk 41, so that the upper surface 41a is optically scanned. .

Since the height of the upper surface 41a matches the height of the lower surface 31 of the clamper 11, the height of the upper surface 41a is the same as the height of the upper surface 41a even if a disk having the same thickness as the disk 21 is installed instead of the disk 41 as shown in FIG. Sa doesn't change.

Therefore, the light beam 14 will be focused on the upper surface 41a regardless of the thickness of the disk 41.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments and can be further modified.

For example, the present invention is not limited to devices that record or reproduce data using information pits, but can also be applied to devices that record and reproduce information by projecting a light beam onto a magnetic recording medium to form reversed magnetization regions.

It is also applicable to devices without an automatic focusing mechanism.

It is also applicable to cases where a disk-shaped recording medium other than a disk is used.

Also, the optical device 13 and the upper surface 21aj of the disk 21j22
22a, if the beam focusing position is not the optimum position due to the refractive index of the transparent resin layer 5, a correction plate made of a transparent plate is inserted between the optical device 13 and the disk 22. You may.

Furthermore, the present invention can also be applied to a device that performs reproduction using transmission rather than reflection of light.

[Brief explanation of the drawing]

Fig. 1 is an explanatory plan view of a video disc, Fig. 2 is a waveform diagram showing part of a composite video signal recorded on the disc, and Fig. 3 is a waveform diagram showing part of a composite video signal recorded on the disc.
4 is an explanatory side view of a video disc player, FIG. 5 is a sectional view showing part of an automatic focusing mechanism, and FIG. 6 is a thick disc in a conventional video disc player. 1 showing the installed state
FIG. 7 is a partial vertical side view showing a state in which a thin disc is mounted on a conventional video disc player.
FIG. 8 is a partially cutaway side view showing a video disc player according to the first embodiment of the present invention with a thick disc installed, and FIG. 9 is a partially cutaway side view showing a video disc player according to the first embodiment with a thin disc installed. FIG. 10 is a side view of the recording/reproducing apparatus according to the second embodiment of the present invention. In addition, in the symbols used in the drawings, 5 is a transparent resin layer, 6 is a pit, 9 is a turntable, 11 is a clamper,
13 is an optical device, 14 is a light beam, 16 is an objective lens,
21 is a first disk, 23 is a second disk, 23,
24 is an engagement hole, 26 is a first disc mounting base, 27 is a first boss portion, 28 is a second disc mounting base, and 29 is a second disc mounting base.
This is the boss part.

Claims (1)

[Scope of utility model registration request] 1. a first disc-shaped recording medium mounting base; a first boss portion formed at the center of the first disc-shaped recording medium mounting base and having a first diameter and a predetermined height; and the first boss portion. a second disc-shaped recording medium mounting base formed on the upper surface; and a second disc having a second diameter smaller than the first diameter formed in the center of the second disc-shaped recording medium mounting base. a first turntable having a first thickness greater than or equal to the predetermined height;
When optically recording or reproducing using a disc-shaped recording medium, the first boss portion is fitted into the center engagement hole, and the first boss part is fitted into the central engagement hole of the disc-shaped recording medium. A disc-shaped recording medium is mounted, and optical recording or reproduction is performed using a second disc-shaped recording medium having a second thickness smaller than the first thickness by the predetermined height. In this case, an optical optical system configured such that the second boss portion is fitted into the central engagement hole and the second disc-shaped recording medium is placed on the second disc-shaped recording medium mounting base. Recording and playback device. 2. The optical recording according to claim 1, wherein the first disc-shaped recording medium and the second disc-shaped recording medium have an optical scanning surface on or near the top surface thereof. playback device. 3. The first disc-shaped recording medium and the second disc-shaped recording medium are such that an information signal is recorded in the form of pits in one force cylinder of the light-transmissive disc, and is projected from the other force side. A utility model according to claim 1, wherein the surface of the force is scanned with a light beam, and an information signal is read by changing the intensity of the reflected light corresponding to the pits on the one surface. Optical recording and reproducing device.