JPS6061965A - Cartridge for video disc player - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a cartridge for, for example, a capacitive video disc player, and more specifically, to an improvement in the tracking performance of a stylus tip to a disc surface. The present invention relates to such a cartridge.

[Background of the invention]

A conventional example similar to the present invention is shown in FIG. The same figure.

A cross-sectional view showing the main parts of the cartridge, with dust and images.

The surface of a video disc 1 on which audio information is recorded.

A stylus (needle) 2 travels through the area, and the recorded information is read as changes in capacitance. Plasti.

Stylus holder 3 made of Tsuku is a stylus.

2 and at the same time eliminates the need for electrical signals from the needle tip.

It has the role of not letting people know about it. .

The cantilever 4 mechanically connects the needle tip and the rubber damper 5. The rubber damper 5 is a force punch.

The role is to fix one end of the bar 4 to the outer shell case 10.

I hold it.

At this time, the needle tip moves upward as disk 1 moves.

As it moves downward and left and right, it also moves back and forth 1' as a jitter correction operation, so it is compensated by the rubber damper 5.

It absorbs the movement of 7 is a fly lead.

A type of dynamic parays that gives stylus pressure.

At the same time, the signal read by the needle tip is transmitted to the next stage.

It acts as a conductive wire that transmits electricity to the road. ``8 is a metal rivet, 9 is a fly lead ball.

7 Rei lead 7 is fixed to case 10. .

In addition, number 6 is a magnet that is installed nearby.

Receiving the electromagnetic force from the Rareda Sentsuka coil, the needle tip is moved from side to side, that is, in a direction that crosses the signal track provided on the video disc 1, and the reproduced image is generated.

Special image playback including fast-forwarding, reversing, and stilling images.

used for.

In contrast, conventional cartridges deteriorate due to heat, etc.

When playing a disc that has been shaped, the stylus tip often does not follow the surface of the disc properly and the stylus skips.

There is a big problem of causing This is the case.

The amount of surface runout of the disk is the same as that of conventional cartridges.

Therefore, the maximum allowable stitches may be exceeded.

This caused needle skipping, so it was necessary to improve the tracking performance and increase the maximum allowable surface runout.

[Purpose of the invention]

An object of the present invention is to provide a cartridge that solves the problems of the prior art as described above and increases the amount of permissible surface runout (Fig. D20). [Summary of the Invention] In order to achieve the above object, the present invention has the following features.

The magnetic force of the magnet in the cartridge.

Using this, the stylus pressure applied to the needle tip is added to the force by the fly lead 75, and the repulsive force of the hard magnet is applied.

of the cartridge by stacking the force due to.

It has improved tracking performance and has a round surface that cannot be played conventionally.

This makes it possible to play discs with large vibrations. .

Below, ten problems with conventional cartridges will be analyzed in detail, and solutions will be specified. .

For discs with large surface runout, which was a problem in the past.

The excitation component it has is comparatively about several H,) to 200 H).

It is a low frequency component. The needle tip movement in this area is No.

Analysis is possible using the equivalent model shown in Figure 2. vinegar! 5, Case 10, fly lead ball! ,vinegar.

7 lie on the fixed end 11 fixed by the bed 8.

One end of lead 7 (metal spring) is fixed and the other end.

is connected to the effective mass Rm of the cartridge vibration system converted to the needle tip. The needle tip is in contact with the disk 1 and is receiving a reaction force from the disk.

In the equivalent model shown in FIG. 2, the conditions under which needle skip does not occur are from the fixed end shown in FIGS. 1 and 2.

Let the distance to the tip of the needle (to the disk surface) be l ('').

and Fs (IK) −m X 1(1)≧Fa−11)
' satisfies the inequality.

Here Fani>)... Hold the fly lead.

Spring force - mxl (i) ・・・Excitation force of disk 1')
0ya)) Yota occurrence.

The inertial force of the needle tip.

Fa...The needle tip is on the disk.

Required to follow.

Minimum stylus force 15 By the way, when considering improving the followability of the needle tip, De.

It is necessary to pay attention to the excitation frequency of the disk. .

That is, the resonance frequency of the vibration system shown in FIG.

There is a lower excitation frequency range and a higher frequency range. There are 20 different methods of improvement, each with a different improvement method, and then improvement methods for each frequency range.

Describe the dan.

[1] The excitation frequency of the disc is the needle tip vibration.

When the resonance frequency of the system is lower.

In this case, it is generally referred to as a "spring region" and is 5F&(6
K))>-mXJ(A)-(2)'' holds true.

Therefore, in this case, the needle pressure curve shown in Figure 3.

With the disk surface facing downward, there is a spring force.

A problem arises when FBCIIi)) decreases. 10
As is clear from the figure, the permissible surface of the disc.

The amount of deflection Δl is due to the fact that the needle tip follows the disk.

Displacement at which the spring force decreases to the minimum needle EE required for this purpose.

defined as a quantity. Therefore, the permissible amplitude amount is improved as the slope of the needle pressure curve is smaller i@, that is, the state shown by the broken line 1i5. (Allowable amplitude amount in the same figure.

Good 1 is (Δl-Δl). ) [2] The excitation frequency of the disk is the vibration of the needle tip.

If the system's resonant frequency is higher than that. .

This case is generally referred to as the "mass region." '.

Needle skipping in this region is due to the inertia of the needle tip.

The car m1(i) is the spring force Fs (1tJ)) in the opposite direction.

and the point of the disk where its value is maximum.

This occurs at a point where the position is (1=-Δj). this.

If the excitation acceleration of the disk at the point is α■, then equation (1) becomes Fa(,+3−Δl)−mXQxm≧Fa−(
3) If Fb-Fs (l・-6g), then.

Fl)-mXαbonito≧ii’a-(4).

Incidentally, the fact that the surface area of the disk becomes large (10) means that the excitation force U speed α fin becomes large in equation (4). Therefore, D.

In order to increase the allowable surface runout amount, either increase the spring force Pb' or decrease the effective mass of the needle tip.

That is. However, the latter has already been reduced in weight to the limit of #1 and there is no means to realize it. Therefore, it can be used for disks with large surface runout, which was a problem in the past.

As a means for improving the needle tip followability, it is effective to increase the spring force Fb'.

By the way, as mentioned before, the maximum excitation acceleration is 20 degrees α-
is proportional to the surface runout amplitude Δl of the disk.

Ru.

Therefore, α=Δ1. β(fs) −(5) 'fsr
i& Disc that gives large amplitude.

Excitation frequency of 5 If you express this, you can make . Substitute equation (5) into equation (4).

When Fb-Δ1. β(fs)≧Fa (6) 'Therefore, fi
'b −Fa Δl ≧β(fs) −+7) 0 That is, V As shown in FIG. It is necessary to set the curve of the broken line 16 with a large slope of the needle pressure curve, and to set the spring force from pb to Fho.

The above can be summarized as follows.

Discs with a large amount of surface runout, which was a problem in the past.

Cartridge needle skipping that occurs when playing.

■The needle when moving upward from the specified disc position.

The pressure curve has a large slope, and the needle pressure curve when moving downward has a small slope.
~13 curve) needle.

You can eliminate skips. In addition, generally the resonant frequency of a needle optical vibration system is 10~! There is a reed around DH7, so the excitation frequency of the disk is high.

(1)% (2) Spreads over both. Therefore to both.

Improvement measures are needed.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described in detail 10 with reference to the drawings.

FIG. 4 is a sectional view of a main part showing an embodiment of the present invention, and the difference from FIG. 1 is that a permanent magnet 14 is provided.

These are 15 points provided near the upper part of the kicker magnet 6 (on the opposite side from the disk surface) so that similar magnetic poles face each other.

Kirakama by introducing permanent magnet 14.

The gunnet is repelled downward by a force called FM. Which force is transmitted to the needle tip and becomes part of the needle pressure. Eternal.

The magnetic force FM due to a long magnet is inversely proportional to the distance between the magnet and the magnet, and therefore, the magnetic force FM.

The relationship with the needle tip position is a curve shown by the broken line 15 in FIG.

In addition, the spring force due to the Fujii lead 7 is the curve 16 in the same figure.
Set it so that In other words, the slope of the stylus pressure curve in the lower CI > 60 range (from the disc specified position) has been made smaller than before, and line 17 in the O drawing shows the force that is a combination of two types of force. . This resultant force is the stylus pressure), and the ideal stylus pressure curve shown in FIG. 3 is realized.

By the way, as a means to improve the tracking performance of the needle tip,
As can be seen from equation (1), it is effective to increase the stylus pressure as shown by curve 18 in FIG.

It is a step. However, in general, the stylus pressure is high and there is a lot of stylus tip wear, and video discs.

It is desirable that the stylus pressure of the cartridge be as low as possible, as damage will be severe.

Therefore, according to the present invention, the specified needle tip position (D.

A means that can improve the needle tip followability without changing the needle EEFO at the second position) is very effective.

It is something.

Also, the above example uses a permanent magnet, but
A similar effect can be obtained using an electromagnet.

〔Effect of the invention〕

As described above, according to the present invention, the work is simple and involves simply arranging a permanent magnet near the magnet without changing the specified stylus pressure, thus without sacrificing the life of the stylus tip or disk damage. The addition of this has a very large effect in that it becomes possible to play video discs with large amounts of damage on the top and bottom surfaces, which were previously impossible to play.

4. Brief explanation of the drawing゛ Figure 1 shows the main components of a conventional cartridge.

2 is a cross-sectional view of a conventional cartridge.

Figure 3 is an equivalent model diagram of the needle tip vibration system.

FIG. 4 is a sectional view of a main part showing an embodiment of the present invention, and FIG. 5 is a characteristic diagram showing an example of the stylus force characteristics in the same cartridge. .

1...Video disc 2...Stylus 6...
Φ Tsuka magnet 7...Fly lead 10...Outer coos 15...Permanent magnet.

0 5 1m old 2nd figure ■ Figure 3 ゛、 ↑ Child%゛ 1°, /″ Ra Asahi, ゛・、 4th m 1M ;F51 yen]

Claims (1)

[Claims] t In a cartridge for a video disc player,
A cantilever holding the needle tip at one end (-゛ needle tip side,
A means for exerting a magnetic repulsion force between the needle tip and a nearby position is provided so that the needle pressure curve of the needle tip shows a non-linear change, and the disk held by the needle tip exceeds the permissible limit. A cartridge for a video disc, characterized in that the stylus tip can secure the necessary stylus pressure when surface runout 1 occurs.