JPS6259384B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic record positioning device that automatically aligns the center of a record with the center of rotation of a turntable.

When playing a record, if the center of the record and the center of rotation of the turntable that rotates the record do not coincide, wow occurs due to eccentricity, and the playback characteristics deteriorate.

For this reason, generally a turntable is provided with a record-fitting shaft (commonly known as a spindle), and a record center hole is fitted into this to position the record relative to the turntable's center of rotation. Each diameter dimension is specified by the standard.

However, for example, in the Japanese Industrial Standards, the outer diameter
In the case of a 30cm LP disc, the eccentricity of the record itself is 0.2
mm, and the diameters of the center hole and the fitting shaft are 7.24 to 7.33 mm and 7.05 to 7.15 mm, respectively, and there is always a gap between them when they are inserted, and this gap is the size of the record and player being used. Depending on the combination, it can become quite large.

Therefore, it is extremely difficult to align the center of the record with the center of rotation of the turntable using only the positioning of the center hole and the fitting shaft, and conventionally, records are played by being placed eccentrically on the turntable. It is normal that
Another drawback was that the degree of eccentricity was largely influenced by how the record was placed.

The present invention solves these conventional drawbacks, and will be described in detail below with reference to embodiments.

First, in the present invention, the eccentric state of the record is detected using the concentric last groove among the various grooves formed on the record. This will be explained using FIG. 1. Concentric final grooves ₁ and 2 formed in a record 1 that is placed on a turntable 3 by fitting 1 into a fitting shaft ₂
The tone arm 5, which is rotatably supported on its support shaft 4, has a light receiving element ₇₁ consisting of a light emitting element ₆₁ such as a lamp and a photodiode etc. A shutter plate 8 located at is attached. Such a well-known optical sensor generates a required electrical signal V whose level changes according to a change in the amount of light, corresponding to the angular displacement of the tone arm 5, and a detailed explanation thereof will be omitted.

On the other hand, a reflecting member 9 is attached to one location on the circumferential surface of the turntable 3, and light emitting elements 62 to 62 are fixedly arranged at a rotational angle of 90 degrees from each other so as to correspond to the mounting position of the reflecting member ₉ . The four optical sensors 10 _{1 to} 10 ₄ each include a light receiving element 7 ₂ to 7 ₅ and a reflecting member 9 at that position.
Each of the required position signals P ₁ to _{P 4} is generated based on the change in the amount of reflected light when the light arrives.

Note that the tone arm 5 is arranged so that the position of the needle tip tracing the final groove ₁₂ is on a straight line connecting two detection points by the optical sensors ₁₀₁ and ₁₀₃ .

In such detection, the optical sensors 10 ₁ , 10 ₂ , 10 ₃ in one rotation of the turntable 3
and 10 ₄ produce respective position signals P _{1 ,} P ₂ , P ₃ and _{P 4} having levels responsive to the angular displacement _of tone arm 5 _. For example, the signals V ₁ and V ₃ are in the illustrated X-X direction connecting the reflection member 9 and the rotation center of the turntable 3, and the signals
V ₂ and V ₄ are information regarding the eccentric state of the record 1 with respect to the rotation center of the turntable 3 in the Y-Y direction perpendicular to the X-X direction, and based on these signals, △Vx = V ₁ - V _3/2 and △Vy = V ₂ - V ₄ /2, a control signal △ representing each eccentricity amount and eccentric direction in the X-X direction and the Y-Y direction is obtained from the value and its sign.
Vx and △Vy can be obtained.

Next, based on the control signals △Vx and △Vy,
The method of correcting the placement position of a record will be explained using the embodiments shown in FIGS. 2 and 3. The turntable has a double structure, corresponds to the turntable 3 in FIG. The main turntable ₃₁ , which is to be aligned with the center of the record, is, for example, directly driven by a motor M.
A reflecting member 9 is attached to the circumferential surface thereof, and a sub-turntable ₃₂ is slidably mounted on the upper surface thereof. The sub-turntable ₃₂ has a standard fitting shaft portion 2 on its upper surface covered with a well-known rubber sheet 11, and a cylindrical engagement shaft 12 having a required diameter on its lower surface at the center of each surface. However, this engagement shaft 12 loosely fits into a through hole 13 having a sufficiently large diameter formed in the center of the main turntable ₃₁ , and extends beyond the lower surface thereof.

On the lower surface of the main turntable ₃₁ , as shown in FIG. one end of each of them abuts the engagement shaft 12. The engagement levers 1x and 1y are each independently displaced to press the engagement shaft 12 by, for example, a cam whose rotation is controlled by a motor (not shown) via a required connection means. The substantially L-shaped lever 1z rotates around the support shaft 15 due to the tension of the spring 14, and rotates the engagement shaft 12 from the opposite direction in response to the combined force of the pressing forces of the engagement levers 1z and 1y. It forms a counter mechanism that presses elastically.

In addition, the motor, cam, etc. are connected to the engagement levers 1x and 1y.
Similarly, it is placed on the bottom surface of the main turntable ₃₁ and rotates together with the main turntable ₃₁ .

In such a configuration, first, the main turntable 3
The cams are controlled by applying the required electrical signals based on the aforementioned control signals △Vx and △Vy obtained regarding the eccentricity of the record with respect to the center of rotation of ₁ to each motor, and the engagement levers 1x and 1y are moved in the required directions. By sliding the record by a required amount, the secondary turntable ₃₂ , that is, the position where the record is placed, can be corrected to align the center of the record with the center of rotation of the main turntable ₃₁ .

As described above, according to the present invention, the record relative to the center of rotation of the turntable is caused by the eccentricity allowed in the record itself and the gap that inevitably exists between the center hole of the record and the fitting shaft of the turntable. The eccentricity of the center can be automatically corrected, thereby effectively eliminating the influence of wah during record playback and significantly improving its characteristics.

Furthermore, the turntable has a double structure consisting of a main turntable and a sub-turntable, and a driving means for sliding the sub-turntable, such as an engagement lever, rotates together with the main turntable. It is possible to make corrections in the following.

In the above embodiment, mechanical means using an engagement shaft and an engagement lever are used, but it is of course possible to use electromagnetic means to slide the sub-turntable relative to the main turntable.

In addition, the arm can be configured with an arm dedicated to detection in addition to the tone arm of the embodiment, and the position of the stylus tip for tracing the final groove or the fixed position of the optical sensor for detecting the position signal can be adjusted according to the embodiment. Although the direction in which the eccentricity of the sensor is measured can be easily determined, the present invention is not limited to this, and various designs can be made based on the required calculations, and it goes without saying that the number of optical sensors is not limited to the example. be.

[Brief explanation of the drawing]

Fig. 1 is a diagram for explaining the detection method according to the present invention, Fig. 2 is a sectional view of the main part showing the turntable structure according to the invention, and Fig. 3 is a bottom view of the main part of the main turntable shown in Fig. 2. Figures are shown respectively. 1...Record, 1 ₁ ...Center hole, 1 ₂ ...Final groove, 2...Record, fitting shaft portion, 3...Turntable, 3 ₁ ...Main turntable, 3 ₂
... Sub-turntable, 5 ... Tone arm, 6
₁ to 6 ₅ ...Light emitting element, ₇₁ to ₇₅ ...Light receiving element, 9...Reflecting member, ₁₀₁ to ₁₀₄ ...Optical sensor, 12...Engagement shaft, 1x, 1y...Engagement lever .

Claims (1)

[Scope of Claims] 1. The eccentricity of the record with respect to the center of rotation of the turntable is detected using a concentric final groove formed on the record, and based on this detection, the mounting position of the record is corrected, so that the record is An automatic record positioning device for correcting the eccentricity of a record, wherein the turntable is composed of a main turntable and a sub-turntable slidably mounted on the main turntable, and the main turntable is An automatic record positioning device comprising: a drive means that rotates about a shaft and slides the sub-turntable to correct eccentricity of the record placed on the sub-turntable and rotated.