JPS6316047Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of the pick-up mechanism in a VHD video disc player, and more specifically to a device that allows a suspension supporting a cantilever to be warmed up before starting playback.

As is well known, in this type of video disc player, information signals such as audio and images are recorded as mechanical irregularities on the surface of a disc made of conductive material, and a playback needle with an electrode attached to the tip of this signal surface is used. By tracing this signal, this signal can be read as a change in capacitance. At this time, the reproducing needle picks up a tracking signal recorded along with the information signal, and is controlled to accurately trace the signal track in accordance with this signal. This regenerated needle is attached to the tip of a cantilever supported by a suspension, and its movement is controlled by changes in the magnetic field created by a needle-driving coil placed around a magnet installed at the base of the lever. .

This control is performed by utilizing the fact that the suspension elastically deforms in a predetermined direction when an alternating current is applied to these coils. Therefore, this suspension is usually made of an elastic material such as natural rubber or synthetic rubber. It is becoming more and more structured.

However, this type of rubber is temperature dependent,
It has the property of being easily affected by the ambient temperature,
In the initial state, the characteristics are generally lower than in the steady state. For this reason, in winter when the ambient temperature is low, if regeneration is started before the suspension has entered a steady state, it will be difficult to make the suspension exhibit the desired performance, and the tracking characteristics will deteriorate, resulting in poor image quality. The problem arises that it is difficult to obtain sound.

This invention was devised in view of the above-mentioned conventional problems, and the purpose of this invention is to enable warming-up of the suspension that supports the cantilever before starting reproduction.

An embodiment of this invention will be described in detail below with reference to the drawings.

Figure 1 shows the main parts of a pick-up mechanism to which this invention is applied.A suspension 1 made of natural rubber, synthetic rubber, etc. is mounted on a coil base (not shown), and a cantilever 2
The connection is supported. A regeneration needle 3 having an electrode is attached to the tip of the cantilever 2, and
A magnet 4 is inserted and fixed to the base of this lever.

A pair of front and rear tracking coils 5a, 5b and 6a, 6b are arranged on both sides of the magnet 4 of the cantilever 2. These coils 5
a to 6b, when the reproducing needle 3 deviates from the center of the signal track during the reproducing process, a kick pulse (excitation current), that is, a tracking control signal is applied based on the difference signal, and the tip of the cantilever is moved so that the difference signal becomes small. The drive is controlled in the transverse direction of the signal track (radial direction of the disk).
When this excitation current is applied to the coils 5a to 6b, a magnetic field in a predetermined direction acts on the magnet 4, producing a torque that rotates the cantilever 2 in a horizontal plane, and the tip thereof is rotated within a predetermined range. ing. This displacement is performed using the elastic deformation and viscous resistance of the suspension 1 that supports the cantilever 2.

Furthermore, a jitter compensation coil 7 is arranged behind the cantilever 2 so as to face the magnet 4. This coil 7 is used when the information signal is a television signal or the like and the reproduced image is shaken.
This is to reduce and compress the jitter component contained in this reproduced signal. When a kick pulse (excitation current) is applied to this, a direct force in the longitudinal direction acts on the cantilever 2 depending on the magnitude and direction of the pulse, causing suspension. The cantilever 2 is displaced in the direction of extension of the signal track (the tangential direction of the disk) against the bending deformation force of the section 1, and the regeneration needle 3 is controlled to be driven in the same direction.

These excitation currents are supplied to each coil from a control section (not shown) built into the device based on the tracking signal.

These coils 5a to 6b and 7 are mounted on a coil base (not shown) so as to surround the magnet 4 from both left and right sides and from the rear as described above.

A stylus pressure coil (not shown) is disposed above the magnet 4 and facing the magnet 4. During playback operation, the playback needle 3 is lowered onto the signal surface of the disc, and a predetermined needle is moved to the playback needle 3 during playback. It is designed to apply pressure.

Therefore, this device is provided with a warming-up circuit 10 for warming up the suspension 1, which drives each of the coils 5a to 6b and 7 to warm up the suspension. It's getting old.

This circuit 10 includes a DC power supply 11 and an oscillation circuit 12, and the output side of the DC power supply 11 is connected to a NAND gate 13 of the oscillation circuit 12 through a terminal a. One NAND gate 14 is connected in series to the output side of the NAND gate 13, and a variable resistor 15 is connected in parallel between both gates 13 and 14. A capacitor 16 is connected in parallel to the output side of the NAND gate 14, that is, in series with a variable resistor 15, and its output is connected to the oscillation circuit 12.
It is said to be the outgoing output.

The variable resistor 15 and the capacitor 16 form a time constant circuit, and the oscillation frequency of the oscillation circuit 12 is determined by the time constant.

In this embodiment, this oscillation frequency is set in advance to have a relatively short period and a small amplitude. These adjustments can be made by appropriately adjusting the resistance value of the variable resistor 15.

The oscillation output from the oscillation circuit 12 thus obtained is supplied to the base of TR ₁ through a resistor 17, and at the same time is inverted by a NAND gate 18 and then applied to the base side of TR ₂ through a resistor 19.

One tracking coil 5a, 5b is connected in series to the emitter side of _TR1 .

Further, the other tracking coils 6a and 6b are connected in series to the emitter side of TR ₂ , and a jitter compensation coil 7 is connected in parallel to these coils 6a and 6b.

TR ₁ and TR ₂ perform a switching operation when the above-mentioned oscillation output is input, and the excitation pulse (excitation current) is transmitted through the resistor 30 to one of the tracking coils 5a,
5b, and at the same time, an excitation pulse whose phase is reversed by 180 degrees from the excitation pulse is applied to the other tracking coils 6a and 6b through the resistor 20. Moreover, at the same time, an excitation pulse having the same phase as that of the coils 6a and 6b is applied to the jitter compensation coil 7.

Furthermore, in this embodiment, a command signal 100 indicating the start of the regeneration operation is applied to the DC power supply 11 through the AND gate 22, and the DC power supply 11 is controlled to generate a predetermined DC voltage by the AND output from the AND gate 22. A voltage is supplied to the oscillation circuit 12 to drive it.

On the other hand, a temperature detector 21 is attached near the suspension 1, and its detection signal 10
1 is input to the AND gate 22. It should be noted that the temperature detector 21 can be configured with various types, and an appropriate one may be selected from among them.

This temperature detector 21 is set to detect the state when the ambient temperature of the place where the main body of the warming-up device is installed is below a predetermined temperature, and output a detection signal 101 to the AND gate 22.

The command signal 100 is set in advance so that its output is automatically stopped when a predetermined period of time has elapsed after the start of the playback operation, for example, just before the start of play.

Next, a suspension warming-up operation using the present apparatus having the above configuration will be explained.

When the player is operated for playback by operating the playback button, the command signal 100 is output to the AND gate 22. At this time, it goes without saying that the disk has been loaded onto the turntable and has started rotating.

When the suspension 1 is at a predetermined temperature or lower and the detector 21 detects this, the detection signal 101 is output to the AND gate 22 as described above. Then, the AND gate 22 receives these two inputs, outputs an AND output to the DC power supply 11, applies a DC voltage to the oscillation circuit 12, and drives the circuit 12. As a result, the bases of TR ₁ and TR ₂ are mutually 180
Oscillation pulses with different degrees and phases are inputted and are subjected to a switching operation. Then, as described above, one tracking coil 5a, 5b, the other tracking coil 6a, 6b, and jitter compensation coil 7 receive excitation pulses (excitation current ) are respectively energized, whereby alternating magnetic flux acting in the tracking direction is applied to both sides of the magnet 4, and magnetic flux in the linear direction is applied from behind. Then, the cantilever 2 vibrates from side to side in the horizontal plane, as shown by arrows 23 and 24 in FIG. 1, and is displaced in the linear direction as shown by arrow 25. As a result, the suspension 1 is elastically deformed in the displacement direction of the cantilever, that is, in the vibration direction and in the linear motion direction, respectively.
This operation is repeated for a predetermined period of time.

Next, after a predetermined period of time has elapsed after the start of the playback operation, when the disc reaches its rated rotational speed and enters a playable state, this is detected and a command signal 100 is issued.
The output of the oscillation circuit 12 is stopped, and the driving of the oscillation circuit 12 is stopped. At the same time, the energization to each of the coils 5a to 6b and 7 is terminated, and the warming-up operation of the suspension 1 is completed.
Furthermore, when the suspension 1 reaches a predetermined temperature or higher due to this warming-up, the output of the detection signal 101 from the detector 21 is automatically stopped.

Corresponding to the oscillation output, the cantilever 2 is set in advance so that vibrations with a short period and a small amplitude and a high speed are applied in small steps.

Thus, the warming-up operation of the suspension 1 is completed, and the characteristics of the suspension 1 are brought to a steady state.

Thereafter, the pick-up is fed in the radial direction of the turntable via a differential gear mechanism by the output of a feed motor (not shown), and positioned above the disk, and then the playback needle 3 is lowered to the signal surface of the disk by the stylus pressure coil. The signal track surface is traced with a predetermined stylus pressure, and the desired reproduction operation is performed.

In the above embodiment, the reproduction operation start command signal 100 and the detection signal 101 from the detector 21 are
Although it has been explained that DC power is applied to the oscillation circuit 12 through the AND gate 22 based on both inputs of Regardless, it may be configured such that the suspension 1 is always warmed up for a predetermined period of time each time a reproduction operation is performed. In this case, the above command signal 1
00 is directly input to the DC power supply 11, and the oscillation circuit 12 is driven based on this input. Therefore, the temperature detector 21, the AND gate 22, etc. are no longer necessary, and the configuration is further simplified.

In addition, in the above embodiment, suspension 1
If the temperature of I've learned not to get caught.

Furthermore, in the above embodiment, the command signal 100
Although it has been described that the signal 100 is input to the AND gate 22 at the start of the playback operation, the signal 100 may be applied to the gate 22 prior to the start of the playback operation. In short, it is sufficient as long as the disc is not in a complete playback mode, that is, before it enters a play state.

As described above, after the start of the playback operation, the suspension 1 is warmed up in advance and transferred to a steady state immediately before the start of play.

Therefore, in the warming-up device according to this invention, it is possible to reliably shift the characteristics of the suspension supporting the cantilever from the initial state to the steady state before the start of the regeneration operation, not only at the initial stage of regeneration but also at all times. This has the advantage that the disc can be played back in good condition.

Furthermore, in this invention, it is only necessary to provide a warming-up circuit to the coil for driving the needle, which is unique to the VHD system, so the structure is extremely simple and the cost is low.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing essential parts of a pickup mechanism to which this invention is applied, and FIG. 2 is a circuit diagram showing an example of the circuit configuration of a warming-up device according to this invention. 5a, 5b, 6a, 6b...Tracking coil (needle drive coil), 7...Jitter compensation coil (needle drive coil), 4...Magnet, 10...
Warming up circuit, 100... command signal for starting regeneration operation, 2... cantilever, 21... temperature detector, 101... (temperature) detection signal.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A magnet is inserted and fixed at the base of the cantilever to which the regenerated needle is attached, and coils for driving the needle, such as a tracking coil and a jitter compensation coil, are arranged around this magnet. A pickup mechanism for a video disk player supported through a suspension made of a rubber material is provided with a warming-up circuit for supplying excitation current to the drive coil to apply an alternating magnetic flux in a predetermined direction to the magnet. 1. A warming-up device for a video disc player, characterized in that the circuit is driven for a required period of time based on a command signal given before the player enters a playback mode. (2) The warming-up device for a video disc player according to claim 1, wherein the suspension is made of a rubber-based temperature-dependent material. (3) A temperature detector is attached to detect the temperature near the pickup section, and the warming-up circuit is configured to be driven by both a detection signal and the command signal input from the detector. A warming-up device for a video disc player according to claim 2 of the utility model registration.