JPS6245602B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pick-up cleaning device suitable for application to video disc players and the like.

In recent years, video signals are recorded on spiral recording lines of a rotating disk-shaped recording medium (hereinafter referred to as a disk), and while this disk is placed on a turntable and rotated, the recording line is A so-called video disk player has been developed that reproduces the video signal by sliding a pick-up needle. In this video disc player, it is of course preferable that the pick-up needle be cleaned in the receiver;
There is no satisfactory cleaning device for this purpose.

This invention has been made in view of the above circumstances, and it is an object of the present invention to provide a pick-up cleaning device that can guarantee the safety of needles and the like and can automatically clean them.

An embodiment of the present invention will be described in detail below with reference to the drawings. First, in FIG. 1, the outline of a video disc player will be explained. Reference numeral 11 is a player body, and a turntable 12 is provided in an opening on the upper surface of the player body 11 in parallel with the opening surface. A disk 13 can be placed on the top surface. This player is
When a play operation is performed, a prismatic box-shaped arm device 15 disposed on the board 14 moves in parallel in the direction of arrow D←→E (radial direction of the disc) shown in the figure. One end in the longitudinal direction is supported and conveyed by a carrying device within the player main body 11. As a carrying device,
The arm device 15 can be conveyed along a predetermined trajectory using a belt drive system or a worm gear. Further, the position of the carrying device is sequentially detected by position detection switches disposed at a plurality of fixed portions during its movement, and the driving direction and the lowering and raising of the needle are changed. In other words,
In FIG. 1, the illustrated position A is the standby position of the arm device 15, the position B is the play start position, and the position C is the play completion position. When a play operation is performed while the arm device 15 is in the standby position A, the arm device 15 is translated in the direction of the arrow D shown in the figure. When the play start position B is reached, a control signal from the position detection switch is sent to the needle lifting device in the arm device 15, and the pick-up needle is lowered. When the play operation progresses and the arm device 15 reaches the play completion position, the needle is raised by the needle lifting device,
Further, the drive means is controlled so that the arm device 15 returns to the standby position A.

Now, to explain the needle elevating device,
In this device, a support lever having a needle at its tip is driven by using, for example, a repulsive force or an attractive force caused by an electromagnetic field, and is raised and lowered from an opening provided in the lower abdomen of the arm device 15.

By the way, a time axis variation correction device is installed in conjunction with the hands. This time axis variation correction device is designed to keep the relative speed between the rotating disk and the recording line sliding needle constant, and can drive the needle forward or backward in the recording line direction.

The above-mentioned time axis fluctuation correction device is constructed as shown in FIG. 2 in terms of block. That is, 20 is an arm stretcher section, and a signal detected by a needle 32 here is applied to a signal reproducing device 21. This signal reproducing device 21 performs FM demodulation of the recorded signal and also extracts the color signal which had been lowered to 1.53MHz. The demodulated output is then applied to a modulator 22 and a voltage controlled oscillator (VCO) 2
It is modulated along with the 5.11MHz output of 7. Therefore, the output of this modulator 22 includes a color signal component centered at 3.58MHz. Here, the 3.58 MHz signal during the burst period is applied to the phase detector 23 and compared with the output (stable 3.58 MHz) of the local oscillator 24 using a crystal resonator or the like to detect a phase error. The error voltage obtained from this phase detector 23 is transmitted to an attenuator 25 and a combining circuit 2.
6 as a control voltage for the voltage controlled oscillator 27. When a control voltage is applied to the voltage controlled oscillator 27, the oscillation frequency of this oscillator is controlled and the modulated output is stabilized. Further, the error voltage from the phase detector 23 can also serve as a voltage for controlling the relative speed of the needle 32 of the arm stretcher section 20 with respect to the disk. In this case, the error voltage is
The signal is applied via a lag lead type low-pass filter 28 and an active low-pass filter 29 so as to be applied to the arm stretcher section 20 in a frequency characteristic range suitable for the relative speed. Further, the voltage applied to the arm stretcher section 20 is also applied to the synthesis circuit 26 via a low-pass filter 30 and an attenuator 31. This is because the so-called automatic frequency control loop (APC loop) consisting of the modulator 22, phase detection circuit 23, attenuator 25, synthesis circuit 26, voltage controlled oscillation circuit 27, etc. is effective in the 3.58MHz band, and the arm stretcher This is to prevent it from affecting the loop. In other words, the arm stretcher loop is composed of the arm stretcher section 20, the modulator 22, the phase detector 23, the lag lead type low-pass filter 28, the active low-pass filter 29, etc., but the frequency range to be controlled is , which is different from the APC loop control target (3.58MHz), is a frequency band related to relative speed. Therefore, in this frequency band, it is necessary to prioritize the gain of the arm stretcher loop.

Next, the principle of the time axis fluctuation correction means associated with the back and forth movement of the needle in the arm stretcher section 20 will be explained. In FIG. 3, 15 is a box-shaped arm device, and an opening ₁₅₁ is provided in the lower abdomen.
A needle arm 33 supporting a needle 32 is disposed in this opening ₁₅₁ obliquely from the inside to the outside. The external tip of this needle arm 33 has a needle 3
2 is attached, and the inner proximal end is fixed to a stretcher attachment piece 35 made of a piece of iron or the like via a damper 34 made of rubber or the like. This attachment piece 35 is attached to the mover 36 of the stretcher body 37 by the attractive force of a permanent magnet or the like. This mover 36
is driven in the direction of the arrow (F←→G) shown in the figure based on the principle of a voice coil of a speaker, etc., and is related to a coil 38 provided within this stretcher. Therefore, the voltage for supplementing the arm stretcher loop described above is applied to the coil 38. Note that the illustrated arrow H←→I of the needle 32
The upward and downward movements in the directions are achieved by the repulsive force or attractive force of the electromagnet 39 disposed in the middle of the needle arm 33. Further, one end of a thin wire elastic spring 40 is curved and connected to the needle 32, and the other end of this spring is connected to a pick-up circuit board 41 attached to a fixed part within the arm device. Normally, the elastic spring 40 has a curvature set so that a biasing force is applied in the direction in which the needle 32 rises, and the electromagnet 39
You only need to apply current when lowering it.

A feature of the present invention in the above-described configuration is that, as shown in FIG. 4, the needle 32, which serves as a pick-up member, can be vibrated for cleaning. A specific example will be explained below. That is, the output of the phase detector 23 explained in FIG. 2 is applied to the input terminal 45 of the amplifier 48. This input terminal 45 is connected to the amplifier 4 through resistors 46 and 47 in series.
It is connected to one signal input terminal of 8. The output terminal of this amplifier 48 is connected to the other bias input terminal of this amplifier 48 via a resistor 49, and the collector of a transistor 50 is also connected. The emitter of this transistor 50 is grounded through a capacitor 51, and the base is connected in the opposite direction through a diode 52 and further through a resistor 53 to a switching signal input terminal 54. A positive or negative voltage is applied to this switching signal input terminal 54 as necessary.
4 is further connected to a forward diode 56 via a resistor 55.
It is also connected to the base of transistor 57 via. The emitter of this transistor 57 is connected to the connection point between the resistors 46 and 47, the collector is connected to the output terminal of the amplifier 48 via the resistor 58, and the output terminal of the transistor 57 is connected via the attenuator 25 described in FIG. It is connected to circuit 26. Further, the output terminal of the amplifier 48 is connected to the lag lead type low-pass filter 28. The output terminal of this lag lead type low-pass filter 28 is connected to an active low-pass filter 29, and this output terminal is connected to the arm stretcher section 20 as described above, and is also connected to the synthesis circuit 26 via an attenuator 31.
It is connected to the. The output terminal of the synthesis circuit 26 is connected to the control terminal of the voltage controlled oscillator 27.

The main part of this invention is constructed as shown in FIG. 4 described above, and its operation will be explained below. First, the transistors 50 and 57 forming the switching circuit are turned off so that the amplifier 48 functions as a mere amplification function during normal signal reproduction. This is done by applying a negative voltage -V to the switching signal input terminal 54.

When the needle 32 is to be cleaned next, a positive voltage +V is applied to the switching signal input terminal 54 and the transistors 50 and 57 are turned on. As a result,
The amplifier 48 and its feedback circuit form an astable multivibrator type oscillation circuit. In this case, the approximate oscillation frequency is determined by the time constant of the capacitor 51 and resistor 49. Since there is a low-pass filter between the oscillation output section and the arm stretcher section, even if the oscillation waveform is a rectangular wave, the input to the arm stretcher section becomes a gentle waveform and the needle does not move suddenly, which prevents needle damage. It is very effective in terms of prevention.

Next, various embodiments are possible as means for switching and setting and applying different voltages to the switching signal input terminal 54. For example, as shown in FIG. 5, when the play operation button 60 is operated, a trigger pulse (which may be noise) is generated, and this triggers the monostable multivibrator circuit 61.
It is also possible to use a means in which the switch circuit 62 selects the positive power supply side for a certain period of time based on this output.

There are various methods for recording signals on a disk. For example, there is a method in which a slot array for FM modulated signals is provided in the recording line and the signal is picked up by changing the capacitance between this and the electrode of the needle. .

Furthermore, the present invention is not limited to the above-mentioned embodiment, and the active low-pass filter 29 may be used as the part forming the oscillation circuit. To explain this example with reference to FIG. 6, the active low-pass filter 29 has a feedback loop 63
has. This loop connects the output end 64 to the resistor 6
It is connected to one bias input terminal (-) of a differential amplifier 69 via a series circuit of capacitors 5 and 66 and a series circuit of capacitors 67 and 68 in parallel.

Further, the connection point between the resistors 65 and 66 is grounded via a capacitor 70. Further, the connection point between the capacitors 67 and 68 is connected to ground via a resistor 71, a resistor 72, and a switch device 73.

Note that the other input terminal of the amplifier 69 is connected to the lag lead type low-pass filter 2 described in FIG.
8 output terminals are connected.

In normal operation, that is, when the switch device 70 is off, the above circuit operates as a filter,
Used for time axis fluctuation correction operation. However, when the switch device 70 is turned on, this filter switches to an oscillator and applies oscillation output to the arm stretcher, which has the effect of removing dirt and dust from the needle by vibration. be.

According to the above-mentioned pick-up cleaning device of the present invention, since a brush that directly touches the tip of the needle is not used, the needle is not damaged and there is no re-adhesion of dust. Further, there is no need to provide a cleaning device using a brush or the like on the player's boat, and no space is required. It is also effective in terms of durability. Furthermore, since the arm stretcher loop is effectively utilized, the circuit is simple and inexpensive.

As described above, the present invention can provide a pick-up cleaning device that guarantees the safety of needles and the like and can automatically clean them.

[Brief explanation of the drawing]

Figure 1 is a schematic explanatory diagram of a video disc player.
FIG. 2 is an explanatory diagram of the configuration of the time axis fluctuation correction device according to the present invention, FIG. 3 is an explanatory diagram of the configuration of the arm stretcher section, and FIG. 4 is a circuit diagram showing an embodiment of the main part of the invention. FIG. 5 is a diagram showing an example of a switching control circuit according to the present invention, and FIG. 6 is a circuit diagram showing another embodiment of the main part of the present invention. 11...Player body, 12...Turntable, 13...Disc, 15...Arm device, 2
0...Arm stretcher section, 21...Signal regenerator, 22...Modulator, 23...Phase detector, 2
4... Local oscillator, 25, 31... Attenuator, 28
...Lag lead type low pass filter, 29...Active low pass filter, 32...Needle, 33...
...Needle arm, 36...Mover, 38...Coil,
48...Amplifier, 50, 57...Transistor,
51... Capacitor, 54... Switching signal input terminal, 65, 66, 71, 72... Resistor, 67, 6
8, 70... Capacitor, 73... Switch device.

Claims (1)

[Scope of Claims] 1. A pick-up member for detecting signals recorded on a disk having a spiral signal recording line; and a pick-up member mounted so as to be movable in the longitudinal direction of the signal recording line. means for generating an error signal for correcting a change in relative velocity between the disk and the pick-up member; and a means for generating an error signal for correcting a change in relative velocity between the disk and the pick-up member; and transmitting the error signal through a signal loop including an amplifier and a low-pass filter. and a means for supplying the error signal to the arm stretcher, the amplifier having an output characteristic switching means, a first operating state in which the error signal is amplified and outputted, and a first operating state in which a predetermined oscillation signal is outputted. and an arm stretcher control loop that can be switched between two operating states, and the amplifier is set to the first operating state during normal playback and switched to the second operating state when cleaning the pickup member. Pip-up cleaning device.