JPS6182348A - Defective state detector of transducer - Google Patents

Abstract

PURPOSE:To detect the defective state of a transducer well by constituting a device so that the device detects that the output of a circuit which performs the reproducing processing of an electric signal does not reach a prescribed output level at a prescribed time. CONSTITUTION:If dust or the like is stuck to a stylus of a pickup 1 to make the reproduced output lower than a prescribed level and this state is continued over a prescribed period when this state can be distinguished from normal drop-out, a command signal is outputted to a driving source 10. The driving source is operated when receiving this command signal, and a notched disc 7 is rotated in the direction of an arrow P. Then, the pickup 1 engaged with a video disc 2 is pushed up by the disc 7, and a cleaning part 9 cleans the stylus while the disc 7 is rotated.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a device for detecting a defective state of a transducer in a video disk or the like. (b) Conventional technology A transducer in a video disc is generally referred to as "one pick-up". The pickup has a stylus at its tip.

In devices that extract signals on the recording medium by bringing the stylus of the pickup into contact with the recording medium, if dust or the like adheres to the stylus of the pickup, the reproduction characteristics will deteriorate, so it is necessary to clean the stylus of the pickup from time to time. be. In pickups that are used for recording media containing video information, the stylus travels a long distance to play back one recording medium, and therefore there are many opportunities for cleaning, so it is common to have a cleaning device attached to the device. . This is common to electromechanical conversion types (contact types) such as piezoelectric types and capacitance types, but
The piezoelectric type will be explained below.

Figure 1 shows the tip of the pickup after the play operation is completed, in which (1a) is a stylus made of a wear-resistant material such as diamond, (1b) is a piezoelectric element, and (1a) is a stylus made of a wear-resistant material such as diamond. 12) shows the dust that adhered during the play operation. If this amount of dust adheres to the stylus, the dust will be interposed between the concavo-convex signal of the recording medium and the scanning surface of the stylus, making it impossible to obtain a normal reproduced signal. For this reason, conventional players are equipped with a leaning device as shown in FIG. In the figure, (1) is a pickup, (2) is a recording medium (video disc), (3) is a motor that drives the video disc, (4) is a transfer device that forcibly moves the pickup in the radial direction of the disc, ( 5
) is the cleaning device, and (6) is the manual transfer knob of the pickup. Here, the cleaning device (5) uses a strip of Japanese paper impregnated with oil, as shown in the enlarged diagram surrounded by a circle. This cleaning system cleans the stylus (1) when the pickup (1) is returned to direction A by the manual knob (6) at the end of the performance.
) comes into contact with the cleaning device (5) and the adhering dust (12) can be removed together with the effect of the oil impregnated into the device, and when the pickup is sent in the direction B, the cleaning is done in the same way.

Cleaning with such a device does not involve detecting the need for cleaning and performing a cleaning action when the need arises, but rather when the stylus of the binkumbu is transferred to the cleaning member. It's just that it's now being done.

(c) Problems to be Solved by the Invention The device shown in Fig. 2 above does not have a device to detect a defective state in which dust or the like is attached to the stylus of the pickup. I can't take any measures.

Therefore, the present invention is applicable to transducers (pickups, etc.)
Provided is a device that suitably detects a defective state of.

(d) Constituent structure of the invention A defective state of a transducer that slides into contact with a recording medium such as a disk and extracts a recorded signal as an electrical signal from the recording medium can be distinguished from a normal dropout in the output of a circuit that reproduces and processes the electrical signal. The configuration includes means for detecting by detecting that the output level does not reach a predetermined level within a predetermined period.

(E) Function If dust adheres to the stylus of the pickup during playback, as shown in FIG. 1, for example, the playback output of the video disc will generally become extremely small.

The difference from normal dropout is that it continues as long as the garbage is not removed.

Therefore, the playback output is monitored and it is detected that the playback output does not reach a predetermined level for a predetermined period of time. Thereby, a defective condition of the stylus can be detected. This detection can be used to clean the stylus. However, in order to avoid cleaning operations even during normal dropout, the period is selected to be distinguishable from dropout.

(f) Example Next, the present invention will be explained with reference to a cleaning device in FIGS. 3 to 6.

The pickup (1) is equipped with a scrill (1a) and a piezoelectric element (1b) at its tip as shown in FIG. I am prepared as follows.

Here, the elastic body (1d) is constructed so as to be able to impart a fairly high co-transmission to the cantilever (1c). This pickup (1) is forcibly transferred by a transfer device (4) as shown in FIG. 2, and for this purpose it is detachably attached to a scanner (not shown) that constitutes the device. (7) is a notched disc with notches (7a) and (7b) in one part, and its surface has a cleaning part made of short-pile 4J, coarse paper, leather, or adhesive material. (8) and constitutes a cleaning member (, L). This cleaning member (9) is attached to a rotating shaft 11 rotated by a drive t1 (10>), and is rotated in the direction P in the figure at a predetermined time to be described later. This drive? Fi, (
10) is a motor that rotates at a speed of 10 revolutions per second or less, or a slide that converts the reciprocating motion of the plunger into rotary motion, which is attached to the scanner and rotates the video disc (2) in the radial direction. It is now possible to transition to In addition, the above-mentioned notched disk
The diameter of 7) is suitably about 2 to 3 cTTl. The shape of the cleaning member (, L) is not limited to that shown in the drawings, and can be modified in various ways. The drive fi<10> is controlled for a certain period of time (T2) by the output of the means for detecting this when the output of the video disc playback circuit remains below a certain level for more than a certain period of time (T1) as shown in FIG.
It is configured to be driven only by the driver. Predetermined period (T1)
The setting deviation is usually good, e.g. by more than 1 second, so as not to respond to the inevitable dropouts in this type of equipment.
Further, the fixed time (T2) may be set to the time required to rotate the cleaning member (and) shown in the embodiment of FIG. 3 by half a rotation. Therefore, when a motor is used as a driving source, a pulse motor is suitable.

When playing, the squillous of the pickup 1) is completely placed in the notch (7a) of the notch disc 7) constituting the cleaning member (disc), and when there is no dust attached to it, ), the reproduction output is made to be at a predetermined level or higher, as shown in the normal period. However, if the playback output falls below a predetermined level due to the adhesion of dust, etc., and this continues for more than a predetermined period (T1), a command to the drive source (10) with a pulse width (T2) is issued as shown in V (b). A signal (D> is output. In response to this command signal, the drive source (10) is activated, and the notched disc (
7) is rotated in the direction P in Fig. 3. Then, Figure 4 (
The pickup (1) engaged with the video disc (2) as shown in (a) is pushed up by this notched disk (7) as shown in (b) of the same figure, and during the rotation of the notched disk, the cleaning unit (9) cleans the stylus (1a). By half a rotation of the cleaning member (9), the pickup (1) falls into the next notch and re-engages with the signal groove of the video disc (2) to perform a reproducing operation. The vertical movement of the pickup is caused by the elastic body of the pink-up (
This is allowed by the elastic deformation in 1d). Although not shown, by providing a guide groove in the cleaning member, the pickup separated from the video disc for cleaning can be returned to near its original position after cleaning.

-8= Fig. 6 shows an embodiment of the detection means (16) in the device of the present invention, (12) is a reproducing circuit into which the signal from the pickup can be input, and (13) is the predetermined voltage (EO) and the a voltage comparison circuit that compares the output of the regeneration circuit (12);
(14) is a time constant circuit that determines the (T+) jot interval;
(15) is a pulse generation circuit triggered by the output of the time constant circuit.

In the above, it has been described that the detecting device for detecting a defective start-up condition according to the present invention is used in a cleaning device by using the detection result thereof, but the application is not limited to the cleaning device.

(G) Effects of the Invention According to the present invention, a defective state of a transducer that is in sliding contact with a recording medium can be suitably detected using the reproduced output.

[Brief explanation of the drawing]

FIG. 1 shows a perspective view of the tip of the pickup, and FIG. 2 is a model diagram of a video disc player including a conventional device. 3 to 6 are diagrams showing the detection device of the present invention together with a stylus cleaning device, and FIG. 3 is a schematic diagram of one embodiment of the cleaning device using the present invention. Figures 4(a) and 4(b) are explanatory diagrams of the operation, where (a) shows the performance state and the figure (mouth) shows the cleaning operation state.Fig. 5(a) shows the playback output waveform diagram, (B) is a command signal waveform diagram in the same figure. Fig. 6 is a block circuit diagram implementing the device of the present invention. (1) ... Pickup (transducer), (2)
)...recording medium, (T1)...predetermined period, ri16)
...Detection means.

Claims (1)

[Claims] (1) A defective state of a transducer that slides into contact with a recording medium and extracts a recorded signal from the recording medium as an electrical signal is detected during a predetermined period so that the output of the circuit that reproduces and processes the electrical signal can be distinguished from a normal dropout. What is claimed is: 1. A defective state detection device for a transducer, comprising means for detecting by detecting that a predetermined output level is not reached.