JPS61129780A - Stylus pressure controlling device of information recording disc reproduction device - Google Patents

Abstract

PURPOSE:To maintain the normal scanning of reproduction sylus regardless of the vibration, by detecting the amplitude of the vibration conveyed from outside which almost corresponds with the proper vibration frequency of the movable parts including the reproduction stylus, and by making variable the stylus pressure according to the detected level. CONSTITUTION:When a reproduction stylus 2 scans a recessed defect, etc. on a disc and the level of a high frequency signal to be reproduced becomes low and the level of the components of frequency band 800Hz of the voice to be pronounced from a loudspeaker becomes high, namely when the amplitude of the vibration which is equal to an intrinsic vibration frequency of the movable parts among the vibration produced by the loudspeaker becomes large, the pressure of a reproduction stylus 2 is increased higher than the normal level, by which the stylus 2 can maintain the normal scanning without entailing mis-scanning or level down of high frequency signal due to the imperfection or the outside vibration. Thus, since the stylus pressure is variable according to the detection level of the outside vibration, the reproduction stylus can maintain the normal scanning, and the wearing of both stylus and the disc can be minimized.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a stylus pressure control device for an information recording disk reproducing device.
The present invention relates to a stylus force control device for an information recording disc reproducing apparatus that reads and reproduces information signals using a reproducing stylus that moves slowly relative to the information recording disc.

・Conventional technology Conventionally, main information signals (
For example, an information recording disk (hereinafter referred to as a "disc") having an electrode performance in which a video signal (including an audio signal) and a first to third tracking control reference signals are recorded as changes in geometrical shape, and There is a device that reads and reproduces the main information signal and the first to third tracking control reference signals as changes in capacitance through relative activity scanning with a reproduction needle (sensor) having an electrode.

In the above-mentioned conventional device, the pressure to bring the playback stylus into contact with the disc, that is, the stylus pressure, is usually kept constant, and the stylus pressure is increased only when the playback stylus scans a concave defective area on the disc, resulting in errors such as erroneous scanning. This prevents the playback stylus from scanning the disc perfectly.

Problems to be Solved by the Invention When using the above-mentioned information recording disc playback device with an audio system such as an integrated amplifier and speakers,
Vibrations generated when the speaker produces sound are transmitted to the playback device.

Furthermore, even when the playback device is mounted on a vehicle and used, the photographed image of the car is transmitted to the playback device. Here, the playback needle of the playback device and the cantilever that supports it have a natural frequency, and if the amplitude of the component equal to the above natural frequency of the vibration transmitted from the outside to the playback device becomes large, the playback needle, etc. There have been problems such as vibrations in resonance with external vibrations, resulting in a reduction in the level of the reproduced high-frequency signal and erroneous scanning of the reproduction needle. It is possible to suppress the vibration of the reproducing needle, etc. by increasing the stylus pressure, but if the stylus pressure is constantly increased, problems such as increased wear on the disk and the reproducing stylus occur.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a stylus force control device for an information recording disk reproducing device that solves the above problems by detecting external vibrations and varying the stylus force according to the detected level. shall be.

Means for Solving the Problems The present invention detects the amplitude of vibration that is approximately equal to the natural frequency of the movable part including the playback needle in the externally transmitted imaging, and varies the stylus pressure according to this detection level. .

Operation In the present invention, the amplitude of the vibration transmitted from the outside is detected to be approximately equal to the natural frequency of the movable part including the needle, and
The stylus pressure is varied depending on the detection level. This increases the stylus pressure when the amplitude increases, making it possible to maintain normal scanning of the reproduction stylus regardless of the presence or absence of vibration.

Embodiment FIG. 1 shows a block system diagram of a first embodiment of the device of the present invention. In the figure, disk 1 is a turntable (not shown)
A playback needle (sensor) is mounted on the surface of the disk 1 and is rotated synchronously at, for example, 900 rpm.
2 is brought into contact with the disk 1 to vibrate and scan the spiral track of the disk 1. The regenerator 2 is fixed to one end of the cantilever 3, and a permanent magnet 4 magnetized in the longitudinal direction of the cantilever 3 is fixed to the base side of the other end of the cantilever 3.

The natural frequency of the regenerator 2, which is a movable part, and the cantilever 3 to which a permanent magnet is attached is, for example, 800H7.

A portion HA of the cantilever 3 closer to the reproduction needle 2 than the position where the permanent magnet 4 is fixed is surrounded by left and right tracking coils 5 and an upper stylus force coil 6. The tracking coil 5 has left and right coils wound in the same phase, and can move the cantilever 3 in either direction in the radial direction of the disk 1 depending on the polarity of the supplied tracking error signal and in accordance with the level of the tracking error signal. displacement a
Displace it with. Also,! The 1-pressure coil 6 moves the cantilever 3 to the disk 1 according to the level of the supplied stylus pressure control signal.
Press in the direction of the surface (downward) to apply stylus pressure to the regenerator 2.

An electrode provided on the regenerator 2 is connected to a pickup circuit 7. The pickup circuit 7 includes a resonant circuit whose resonant frequency changes in response to changes in the electrostatic capacitance formed between the electrode and the disk 1 in accordance with the intermittent bit strings on the surface of the disk 1, and a resonant circuit that changes the resonant frequency in response to changes in the capacitance formed between the electrode and the disk 1 in accordance with the intermittent bit strings on the surface of the disk 1. a circuit that applies a constant frequency; a circuit that detects the amplitude of a high-frequency signal whose amplitude changes according to a change in the capacitance from the resonant circuit;
It is composed of a circuit that pre-amplifies this amplitude-detected high-frequency signal (RF multiplied signal).The high-frequency signal extracted from this pickup circuit 7 is supplied to a demodulation circuit 8, where the main information of the main track is The signals (audio signal and video signal) are demodulated.

Further, the high frequency signal is supplied to a tracking control circuit 9 and a level detector 10. The tracking control circuit 9 receives first to third tracking signals fpI from among the high frequency signals.
- Frequency selection and extraction of fp3. Furthermore, a switching pulse is generated from the tracking signal rp3, and the tracking polarity is switched by this, and the tracking signal @f
P I +rp 2 is operationally amplified, and the tracking deviation υ
A tracking error signal having a level corresponding to the tracking error direction and a polarity corresponding to the tracking deviation direction is generated, and is supplied to the tracking coil 5 described above. The level detector 10 detects the peak value of the high frequency signal, generates an RF level detection signal that becomes L level when this peak value exceeds a predetermined reference level, and becomes H level when it is below the reference level, and uses this as a needle. Supplied to the pressure control circuit 11.

For example, an audio signal supplied to a speaker enters the input terminal 12 , and this audio signal is supplied to a bandpass filter 13 . The bandpass filter 13 passes only signals in a band centered on a frequency of 800Hz, which is equal to the natural frequency of the cantilever 3, etc.
The 00H2 component is extracted and supplied to the level detector 14. The level detector 14 detects the peak value of the 800Hz signal, and generates an audio level detection signal that becomes H level when this peak value exceeds a predetermined reference level, and becomes L level when it is below the reference level. , stylus pressure control circuit 1
Supply to 1.

The stylus pressure control circuit 11 generates a stylus pressure control signal at a predetermined DC level and supplies it to the stylus pressure coil 6 in a normal reproduction state in which the level detection signals from the level detectors 10 and 14 are both at L level. Further, when at least one of the level detection signals of the level detectors 10 and 14 reaches the H level, the stylus force control circuit 11 generates a stylus force control signal with a level higher than the predetermined DC level, and sends the stylus force control signal to the stylus force coil 6. supply

In other words, when the reproduction meter 2 scans a concave defective part etc. on the disc and the level of the reproduced high frequency signal becomes low, and the frequency control 800 of the sound emitted from the speaker
When the level of components 1 to 12 becomes large, that is, when the amplitude of the vibration equal to the natural i rib of the movable part among the vibrations generated by the speaker becomes large, the stylus force of regenerator 1 becomes normal. considered to be larger. As a result, playback total 1 is disk 1
Normal scanning is possible without causing a drop in the level of the reproduced high-frequency signal, erroneous scanning, etc. due to defects or the influence of imaging.

FIG. 2 shows a block system diagram of a second embodiment of the device of the present invention. In the figure, the same parts as in FIG. 1 are designated by the same reference numerals, and their explanations will be omitted. In FIG. 2, converter 15 converts @ribs into electrical signals. The electrical signal obtained thereby is supplied to the bandpass filter 16, where the frequency filter 800
The Hz component is extracted and supplied to the level detector 17. The level detector 17 detects the peak value of this signal,
When the peak value exceeds a predetermined reference level, it becomes H level; when it is below the reference level, it becomes L level, and a bell detection signal is generated. This imaging level detection signal and the level detector 14
The audio level detection signal is added and mixed, that is, ORed, in the adder 18, and the detection signal obtained here is supplied to the stylus force control circuit 11.

In the 5A position shown in the second diagram, when the level of the high frequency signal becomes small and the level of the sound equal to the natural frequency of the movable part becomes large, the lateral pressure becomes larger than normal. When the level of mechanical tri iFl+ equal to the above-mentioned natural frequency becomes large, the stylus pressure is made larger than usual. In addition, since the normal stylus force is the same as the conventional device, the disk 1
And the wear of the regenerator 2 will not become large.

In addition, in FIG. 2, when the electrical signal output from the converter 15 is at the same level as the audio signal input to the terminal 12, the electrical signal is directly supplied to the bandpass filter 13.
Bandpass filter 16. It is not necessary to provide the level detector 17 and the adder 18, and the present invention is not limited to the above embodiment.

Effects of the Invention As described above, the stylus pressure control device of the information recording disc playback device according to the present invention detects external vibrations and varies the stylus pressure according to the detection level, so that the influence of external vibrations is reduced. The level of the high-frequency signal reproduced from the disk (disc) will not drop, and the reproduction needle will not cause erroneous scanning, allowing normal scanning to be performed.The normal stylus force is the same as the conventional one, It has the advantage of being able to keep wear on the recycled needle to a minimum.

[Brief explanation of the drawing]

FIGS. 1 and 2 are block diagrams of each embodiment of the apparatus of the present invention. 1... Disc, 2... Playback needle (sensor), 3...
・Cantilever, 6... Needle pressure coil, 7... Pickup circuit, 10, 14.17... Level detector, 1
1...Stylus pressure control circuit, 13.16...Band filter. Figure 1 Figure 2

Claims (1)

[Claims] In a stylus pressure control device of a reproducing apparatus that reads and reproduces information signals using a reproducing stylus that slides relative to an information recording disk on which information signals are recorded on a spiral track, vibrations transmitted from the outside and/or A vibration amplitude approximately equal to the natural frequency of the movable part including the regeneration needle is detected from a signal at a level corresponding to the vibration, and the stylus pressure of the regeneration needle is varied in accordance with the detected level. A stylus force control device for an information recording disc playback device.