JPS58143451A - Pickup of video disk reproducing device - Google Patents

Abstract

PURPOSE:To prolong the life of a stylus and to realize long-period reproduction, by forming a piece of consumption which is at right angles to and nearly as wide and thick as the base body of the stylus in one body to a right-angled parallelepiped shape. CONSTITUTION:The stylus 1 has the piece of consumption 12 projecting downward by being cut in one body from the base body 10 nearly in a triangular pyramid shape and on the vertical surface of the piece 12, an electrode plate 2 is provided. The piece 12 of consumption has about 2mum thickness (b) and parallel side walls 14 and is formed to uniform width lb. A contacting surface 11 formed under the piece 12 has starting length la, but it reaches maximum length lb(>la) of consumption by friction against disks and also reaches starting height ho of wear. Then, the wear of the piece 12 continues, but the width is still the maximum length lb of wear; and a wron part in a right-angled parallelepiped shape parallel to the vertical surface 13 is formed, so long-period signal reproduction is performed until the height attains to effective height (h).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a CED (capacitance electric disk) pickup in a capacitive video disc playback device.

A capacitive video disc playback device uses a video disc in which signal grooves are formed on a vinyl chloride plate mixed with isochoric carbon particles, and the pickup of the playback device is moved relative to the video disc. , the signal is extracted from the electrode plate on the pickup.

A stylus is fixed to the pickup to keep the electrode plate always at a constant height from the disk surface without being restricted by the depth of the groove on the disk and the length of the groove along the track direction.

By placing the electrode plate on the stylus, the electrode plate detects changes in capacitance due to changes in the gap between the signal groove and the electrode plate, applying the function of a so-called air capacitor. It is something.

In the capacitance type CED (capacitance electric disk) system, the shape of the signal groove carved into the disk is continuous in the track direction of the disk.

In the conventional stylus (1) of the CED method, the overall shape of the base (10) is approximately an inverted triangular pyramid, as shown in FIG. A vertical surface 031 is formed toward the downstream side in the track direction (4). Also, track direction (4)
An apex Q7] is formed toward the L-flow side.

A consumable piece U is integrally formed on the disk (3) side of the stylus (1), and both side walls 0a of the consumable piece U are formed on the disk (3) side of the stylus (1).
The signal groove (3) is cut approximately parallel to the track direction (4) into 11 dimensions corresponding to the width of the signal groove. However, strictly speaking, the thickness formed between the side wall +14)04 is cut slightly narrower than the width of the signal groove (to).As shown in Fig. 9, the consumable piece (121) comes into contact with the signal groove circle. The contact surface 01) is cut to match the angle of the approximately square cross section of the signal groove (2), and the electrode plate (2) is mounted on the vertical surface (13).

An acute flank 06) is formed on the bottom surface of the stylus (1), so that if there is dust etc. on the signal groove, the consumable piece t
This prevents the pickup from dropping out due to accumulation on the i21 or dust. However, as the conventional stylus (1) accumulates the playback time of the video disc, the contact surface αυ of the stylus (1) increases.
The disc gradually wears out due to the relative motion friction with the disc, and normal signal reproduction becomes impossible. Specifically, as shown in FIG. 9, the initial length l! of the contact surface circle is l is formed to be 5 μm, but if wear progresses and the maximum wear length 12 of the contact surface exceeds 10 pm, the state of engagement with the signal groove will deteriorate,
Dropouts and other problems occur frequently due to deterioration of stylus trackability. This results in the effective height hO of the vertical surface 131 on which the electrode plate (2) is mounted.
Also, the maximum consumption length l! The life limit is determined by the dimension 10Pm of No.2.

The present invention provides a stylus whose lifespan is significantly longer than that of conventional styluses, and the length of the contact surface of the stylus is extended by forming a substantially straight rectangular parallelepiped with a length within the lifespan limit. It has a consumable piece that can regenerate time.

The present invention will be described in detail below based on embodiments shown in the drawings.

The base of the stylus according to the present invention is made of diamond and has a substantially inverted triangular pyramid shape with a truncated head, and is finished into a predetermined shape, similar to the conventional stylus described above. 1st
The figure shows the finished shape of the stylus +1) according to the present invention, which is integrally machined from a base αe in the form of an approximately inverted triangular pyramid with the top end cut off, and a consumable piece G protruding downward is formed. , an electrode plate (2) is mounted on the vertical surface f131 of the consumable piece (2).The consumable piece (a) protruding from the lower surface of the base +10 has a thickness b- as shown in FIG. The contact surface (11) formed at the bottom of the consumable piece d has an initial length of Although it is ja,
Maximum wear length 7 due to wear due to friction with the disc
b (>la) and also reaches the initial wear height hO. After that, a consumable piece (1 steep wear continues, but the width is the maximum wear length zb) and a rectangular parallelepiped-shaped consumable part parallel to the vertical plane 0 steep is formed, so the effective height h Signal regeneration is possible for a long time until reaching .

The specific dimensions and shape of the consumable piece a2 in this embodiment are as follows:
141 (thickness b of 1Φ is finished to 2υm, and while the width of the signal groove on the disk is 2.6μm, a narrow gap of about 0.3υm is formed on both sides.

The contact surface (11) has a groove angle 140 of the V-shaped cross section of the signal groove.
It is formed into a V-shape with an opening angle of 1400 degrees. In Fig. 3, the length/a of the contact surface (111 is 5
μm, and the maximum length l! when the contact surface (11) wears out. b is 10Pm. The height h of the consumable piece α2 is finished to 10 μm from the lowest end of the contact surface (1υ), taking into consideration the mechanical strength against breakage during machining of the consumable piece and disk tracking. However, depending on the processing conditions The height h can also be set to a maximum of 15 μm.

Processing of the consumable piece a2 is carried out using an abrasive body (5) shown in Fig. 4. The abrasive body (5) is driven to rotate around a rotation axis (to), and is formed with a concave shape along the circumferential direction. Grooves 151 are provided, and an abrasive layer (2) using powdered diamond, powdered sapphire, oxide, or the like as an abrasive material is formed on the surface of the abrasive body (5).

The width of the concave groove 61) of the abrasive body (5) is formed to the finished size of the consumable part. When processing the consumable piece u4, it can be formed into the shape of a groove by pressing the base 0 (I) of the stylus (1) downward from above the groove t511. It is processed and formed in the same way as the one above.

The electrode plate (2) attached to the vertical surface α■ of the stylus is formed by a known film forming technique.

However, as the playback time of the video disc accumulates, the consumable piece formed on the stylus (1) wears away, and as shown in Fig. 3, the contact surface length of the consumable piece (12) is equal to the initial contact surface length. The maximum consumable length lb is reached from the initial contact surface length/a. Conventionally, if this maximum consumable length lb is even slightly exceeded, it is considered unusable and is discarded, but in the present invention, the maximum consumable length lb is reached from the initial contact surface length/a. (Even if this point is reached, the height of the remaining consumable piece h-ho) is formed to have a uniform width equal to the maximum consumable length/b, so signal generation can be performed for a longer time than before. If the stylus comes into contact with a video disc rotating at 450 rpm with a suppressing load of 60 m'i, the diamond friction per unit time is on the order of 2 x 10-2 μm3, so the conventional stylus has a long service life. The lifespan of 1
However, according to the present application, the target volume can be set to 70 to 80 μm3, so the lifetime is 3500 hours.
~4000 hours are obtained.

5(a)(b)(C), FIG. 6 and FIG. 7 show other embodiments of the shape of the stylus l), and FIG. 9J5(a).
) is a curved surface (6) at the boundary between the upper base (1α and the consumable piece α).
It has been established. FIG. 5(b) shows an upper substrate αQ formed with an inclined surface (7) extending upward from the root of the consumable piece. In FIG. 5(C), the vertical surface +13) to which the electrode plate (2) is fixed is provided with an inclination such that the consumable piece becomes narrower toward the tip.

In FIG. 6, the upper base body (101) is provided with inclined surfaces +81 to +81 that extend upward from the base of the consumable piece az.

In FIG. 7, the back surface (8) of the consumable piece A facing upstream in the track direction is sloped equiangularly.

The present invention is constructed as described above, and even if the contact surface of the stylus consumable piece α2 wears out as described above, the maximum wear length reaches the limit of its life! By forming the stylus into a substantially columnar shape that can be maintained at 2 or less, the life of the stylus is significantly extended compared to conventional styli.

It goes without saying that the present invention is not limited to the above configuration, and that various modifications can be made within the technical scope of the claims.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a stylus according to the present invention, FIG. 2 is a side view of the stylus, FIG. 3 is a front view of the stylus, and FIG.
The figure is a sectional view of the abrasive body (5) showing the processing state of the stylus, Figures 5 (a), (b) and (ε) are front views showing another embodiment, and Figure 6 is a side view showing another embodiment. FIG. 7 is a bottom view showing another embodiment, FIG. 8 is a perspective view of essential parts showing how the conventional stylus is used, and FIG. 9 is a front view of the conventional stylus. (1)...Stylus (2)...Electrode plate (3
)...Video disc α [...Base 0ri...
Consumable piece Applicant Sanyo Electric Co., Ltd. Procedural Amendment θ Method> May 13, 1980 To the Commissioner of the Japan Patent Office 1, Indication of case: Japanese Patent Application No. 57-264282, Title of invention: Pick-up of video disc playback device 3,
Person making the amendment Applicant's name (188) SANYO Electric Co., Ltd. 5. Drawings to be amended, claims and detailed description of the invention column 6. Contents of the amendment (2) "No. Added the code +71 (7) to the attached sheet ``Figure 6'' as shown in red ink in ``Figure 6''. (3) "Figure 8" in the drawing was corrected to the attached sheet "Figure 8". (4) In the drawing, the symbol α force was added to "Figure 9" as shown in red ink in the attached sheet "Figure 9". (5) The “Claims” in the specification have been amended as shown in the attached sheet. (6) "Electric" was corrected to "electronic" on page 2, lines 2-3 of the specification. (7) Specification rate: From line 19 on page 2 to line 2 on page 3, ``Electronic...'' is glossed over. In the ``electronic disk'' system, the signal engraved on the disk is continuous in the track direction. "Corrected by engraved with uneven shapes." (8) On page 3 of the specification, lines 4-5, "base body... orthogonally" is changed to "the tip shape of the base body Uα is approximately an inverted triangular pyramid, and is perpendicular to the surface of the disk (3). Corrected to "Like". (9) Page 5, lines 5-6 of the specification: ``Material......substantially inverted triangular pyramid J'' has been corrected to ``substantially inverted triangular pyramid as material.'' In the specification, page 5, lines 8-9, "upper part...approximately inverted triangular pyramid" has been corrected to "approximately inverted triangular pyramid". (I'll correct "signal available" on page 7, line 20 of the specification to "signal regeneration.") Scope of Claims ■ An electrode plate is fixed to a stylus attached to a pickup, and image signals, audio signals, etc. are transmitted from the signal groove. A pickup for a video disc playback device using a capacitance method for extracting necessary signals, in which a consumable piece integrally formed on the base of a stylus is formed into a straight rectangular parallelepiped with approximately equal width and thickness. ■ The stylus attached to the pickup is used for CED (capacitance electronic disk) video discs that form a continuous signal groove, and is a rectangular parallelepiped with a straight, approximately equal length and thickness below an inverted triangular pyramid. A pickup for a video disc playback device according to claim 1, wherein the consumable piece is integrally formed.

Claims (1)

[Claims] ■ In a video disc playback device using a capacitance method in which an electrode plate is fixed to a stylus attached to a pickup and necessary signals such as image signals and audio signals are extracted from a signal groove, the stylus is A pickup for a video disc playback device in which a consumable piece integrally formed with a base is formed into a straight rectangular parallelepiped having substantially equal width and thickness. ■ The stylus attached to the pickup is used for CED (capacitance electric disk) video discs that form a continuous signal groove, and is straight below the truncated inverted triangular pyramid and has approximately the same width and thickness. 2. A pickup for a video disc playback device according to claim 1, wherein a consumable piece having a rectangular parallelepiped shape is integrally formed.