JPS606002B2 - Pickup for video disc - Google Patents

Description

[Detailed description of the invention] The present invention relates to a pickup for video discs.

A conventional video disc pickup using a pressure playback method uses a single stylus to track record grooves and playback signals.

Generally, on a video disc, a large amount of information must be recorded in a limited area, resulting in high-density recording, and the depth of the record groove is minute, on the order of several meters. It becomes difficult for the playback stylus to track the record groove.

In addition, compared to ordinary audio records, the records of video disc devices have a higher rotational speed (for example, 90.
．． m) Due to the friction between the record and the stylus, the record is charged with static electricity and easily attracts dust, and in order to further reduce the friction between the record and the stylus, lubricating oil is applied to the surface of the record. There is a problem in that dust or small pieces scraped from the record as the stylus scans firmly adhere to the surface of the record, causing stylus jump during playback.

In order to solve these problems, increasing the stylus pressure improves the tracking ability of the stylus even if there is a small amount of dust, but this not only interferes with Takagi signal reproduction, but also accelerates stylus wear, resulting in a stable image. This has the opposite effect on playback.

The present invention solves the above-mentioned drawbacks, and the pickup is provided with a tracking needle in addition to the playback needle, and the tracking needle allows the pickup to gradually give way as the record rotates, and also allows the pickup's own weight to be regenerated. It reduces the proportion of the stylus applied to the stylus, reduces the stylus pressure of the playback stylus, and "before the playback stylus scans the record groove, it scans the record groove and removes foreign matter inside the record to ensure a stable playback signal. It is designed so that it can be obtained.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a video disk pickup according to the present invention, which is characterized in that a supporter 6 is provided with a signal reproducing needle 2 and a tracking needle 3. The signal reproducing needle 2 is firmly fixed to a piezoelectric transducer 4, which is held by a support 61 via an elastic damping layer 5. The pressure change between the record 1 and the playback needle 2 is then extracted from the piezoelectric transducer 4 as an electrical output. On the other hand, the tracking needle 3 is directly fixed to the support 6. In such a configuration, when stylus pressure is applied by the supporter 6, only a relatively small pressure is applied to the signal reproducing needle 2 because it is elastically held by the supporter 6, but a strong force is applied to the tracking needle 3. Pressure is added.

Note that since this tracking needle is not used for signal reproduction, a sharp edge is not required, and a rounded edge may be used.
Therefore, even if strong pressure is applied, the grooves of the cord blade will not be damaged. The tracking needle 3 is fixed to the supporter 6. Even if the sample cord oscillates vertically, the supporter 6 will also move as the record fluctuates. The record groove can be stably tracked without any change in the stylus pressure that occurs during the recording. It is not necessary to match the groove spacing accurately.Furthermore, the tracking needle 3 is placed to the left of the signal playback needle with respect to the paper surface of FIG. The tracking needle 3 is arranged to scan the record groove ahead of the playback needle 2. Therefore, the signal playback needle 3 is stabilized because the tracking needle 3 blows off the dirt attached to the record groove before the playback needle 2 scans the record groove. The signal can be detected.
A method of applying a needle pressure difference between the signal reproducing needle 2 and the tracking needle 3 will be explained with reference to FIG.

6 is a support, 2 is a signal reproducing needle, 5 is its attenuation layer, 3 is a tracking needle, and 7 is its support.

By making the tracking stylus 3 longer than the signal reproducing stylus 2 by h or by making the support 7 harder than the damping layer 5, stylus pressure is mainly applied to the tracking stylus and the signal reproducing stylus traces the record book. Fig. 3 is a view from above the needle tip.

The signal reproducing needle 2 and the tracking needle 3 are placed on the supporter 6 as shown in the figure. During playback, the tracking needle traces the groove in front of the signal playback needle, so a lot of dust adheres to it, and the distance between the two needles on the running side is
If the distance is not sufficient, the dust attached to the tracking needle may have an adverse effect on the signal reproduction needle, so this distance must be maintained.Also, as shown in Figure 3, compare the interval S in Figure 3 above. When the target is longer, the supporter 6 is lowered, and when pressure is applied to the fracking needle 3 and the regeneration needle 2, pressure is gradually applied from the tracking needle 3 at the tip until the fulcrum of pressure shifts to the rear needle. Pressure is mainly applied to the tracking needle at the tip.

Therefore, it is desirable to arrange the tracking needle 3 at the tip of the supporter and the t-signal reproducing needle 2 at the rear. As described above, according to the present invention, the record groove is shallow in order to guide the support device provided with the reproduction stylus by the tracking needle that engages with the record groove with a greater stylus pressure than the reproduction stylus.
It is possible to stably scan the playback stylus along the record groove with low stylus pressure.In addition, since the tracking stylus with high stylus pressure scans the record groove before the playback stylus scans, it is firmly attached to the record groove. Fixed foreign objects can also be removed by cutting.

Furthermore, since the playback stylus is more elastically attached to the same support in the direction perpendicular to the record surface than the tracking stylus, even if the stylus pressure applied to the tracking stylus changes due to the surface runout of the record, the playback stylus remains unchanged. Fluctuations in the dynamic pressure with the disk are reduced. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of essential parts of an embodiment of the pickup of the present invention, and FIG.
The figure is a perspective view of the configuration that mainly applies pressure to the tracking needle, FIG. 3 is a plan view showing the positional relationship between the signal reproducing needle and the tracking needle to prevent dust from affecting the signal reproducing needle, and FIG. The figure is a side view when the tracking needle and the signal reproducing needle are arranged in the track linear direction.

2... Signal reproducing needle, 3... Tracking needle, 4... Piezoelectric element, 5... Elastic damping layer, 6... Support device.

・Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. A tracking stylus and a signal reproducing stylus, each of which engages with a record groove on a record, are arranged such that the stylus for reproducing is more elastic in a direction perpendicular to the surface of the record than the stylus for tracking. The tracking needle and the signal reproducing needle are arranged on the same support so that their needle pressure is greater than the needle pressure of the signal reproducing needle, and the tracking needle and the signal reproducing needle are mounted on the support by the tracking. A pick-up for a video disc, characterized in that a stylus is positioned ahead of the signal reproducing stylus to scan a record groove on the record.