JPS6214894B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for recording and reproducing signals such as video signals and audio signals using a recording medium using a semiconductor.

In recent years, the development of video discs that record video signals at high density has progressed and is attracting attention. However, all conventional video disc systems are playback-only, and there is a problem in that the user cannot record signals arbitrarily.

In order to solve these problems, the inventors have proposed a system that can arbitrarily record video signals and the like at high density using a recording medium using a semiconductor. Figure 1 shows an overview of this type of signal recording and reproducing device.
This is an example of a NOS structure. That is, the recording medium 1 includes an SiO 2 film 3 as an insulating film having a charge storage function on a semiconductor substrate ₂ such as a Si substrate.
Si ₃ N ₄ film 4 is laminated to a thickness of several hundred Å, and the entire structure is shaped like a circular disk. It is placed and fixed face down.

During signal recording, the tip of the conductive head 5, which has a thin electrode 6b formed on the side surface of an insulating substrate 6a such as sapphire, is brought into contact with the surface of the Si ₃ N ₄ film 4.
Move this relatively as shown by the arrow. Actually, the recording medium 1 is rotated together with the turntable 5. Then, a recording signal voltage 7 digitized into binary values of "1" and "0", for example, is applied between the conductive head 6 and the turntable 5, that is, in the thickness direction of the recording medium 1.

In this way, due to the electric field generated by the recording signal voltage 7, charges in the semiconductor substrate 2 are trapped and accumulated in the Si ₃ N ₄ film 4 by a tunnel effect. As a result, a change in the recording signal voltage 7 on the semiconductor substrate 2,
That is, the depletion layer 8 is formed corresponding to the charge accumulation state of the Si ₃ N ₄ film 4. For example, if the recording signal voltage 7 is digitized, Si ₃ N ₄
Charges are selectively accumulated in the film 4 and the semiconductor substrate 2
A depletion layer 8 is formed only directly under the region of the Si ₃ N ₄ film 4 where charges are accumulated.

On the other hand, in order to reproduce the signals recorded in this way, the conductive head 6 is brought into contact with the surface of the Si ₃ N ₄ film 4, and the conductive head 6 is moved through the head 6 while relatively moving along the recording track. This is done by detecting changes in capacitance in the thickness direction of the recording medium 1 due to the depletion layer 8. As a means for detecting this change in capacitance as an electrical signal, it is appropriate to use, for example, a resonant circuit.

By the way, during recording, signals are recorded on the recording medium 1 as concentric or spiral tracks, but in this case, in order to record efficiently without intersecting with already recorded tracks, it is necessary to record new signals. Generally, the track position is determined based on the most recently recorded track position.

However, determining the position of the track to be recorded first, searching for the first recorded track, etc. cannot be performed using the above-mentioned method based on already recorded tracks.

This invention was made in view of the above points,
A sawtooth metal film pattern is formed along the circumferential direction of the recording medium on the peripheral part of the surface of an insulator film with a charge storage function formed on a semiconductor substrate, and the light reflectance due to this metal film pattern is The present invention provides a signal recording and reproducing device that detects a change or a change in the electrical characteristics of a recording medium in the thickness direction and uses the detected signal as a control signal during recording or reproduction.

Hereinafter, this invention will be explained in detail with reference to Examples.

FIG. 2 shows an embodiment of this invention.
A feature is that a metal film pattern 9 is formed around the surface of the Si ₃ N ₄ film 4 of the recording medium 1 by vapor deposition, sputtering, ion plating, or other methods. The metal film pattern 9 is formed, for example, in a sawtooth shape along the circumferential direction of the disk-shaped recording medium 1, as shown in FIG. A photodetector 10 is provided above the metal film pattern 9 to detect a change in light reflectance on the surface of the recording medium 1 due to the pattern 9. This photodetector 10
is adapted to move in the radial direction over the recording medium 1 in conjunction with the conductive head 6.

In this case, the photodetector 10 faces a location where the metal film pattern 9 is present and a location where the metal film pattern 9 does not exist and the Si ₃ N ₄ film 4 is exposed. Since the output is reversed, as the recording medium 1 is rotated by the turntable 5,
A pulse train as shown in FIG. 4 is generated as a detection signal. The pulse width of this detection signal depends on the circumferential width of the metal film pattern 9, and when the photodetector 10 is on the outer circumferential side of the recording medium 1, the pulse width is wide as shown in a, and shifts to the inner circumferential side. As it goes, it becomes narrower like b and c.

Therefore, by setting the position of the conductive head 6 when the pulse width reaches a certain predetermined value, the position of the track to be recorded first can be determined. Furthermore, during reproduction, if the position of the conductive head 6 is set at a location where the pulse width has the same value as above, the first recorded track can be searched.

Furthermore, since the period of the pulse train that is the detection signal of the photodetector 10 depends on the rotational speed of the recording medium 1, it is also possible to control the rotational speed of the motor that drives the turntable 5 using this pulse train. .

Here, it is naturally impossible to record signals in the area where the metal film pattern is formed on the recording medium 1, but in this invention, the metal film pattern 9
Since it is formed as a sawtooth pattern on the periphery of the disk-shaped recording medium 1, it has the advantage of being easy to manufacture. In other words, if a metal film pattern is to be formed in the radial middle part of a recording medium where signals are recorded, the metal film pattern needs to have a very fine shape so as not to interfere with recording, and its formation is difficult. Not only is this difficult, but peeling is also likely to occur. In this regard, since the sawtooth metal film pattern 9 in the present invention is formed on the peripheral portion of the recording medium 1 which is not normally used for recording signals, it may be relatively large in shape and is therefore easy to form. , there is no risk of peeling.

Note that a detection head similar to the conductive head 6 is used in place of the photodetector 10, and changes in the electrical characteristics of the recording medium 1 in the thickness direction, such as changes in capacitance or electrical resistance, are detected through this detection head. Detection may be performed to obtain a similar detection signal.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an outline of a signal recording/reproducing device using a recording medium using a semiconductor, FIG. 2 is a sectional view of an embodiment of the present invention, and FIG. 3 is a plan view of the main part of the embodiment. FIG. 4 is a waveform diagram for explaining the operation. 1... Recording medium, 2... Semiconductor substrate, 3... SiO ₂
film, 4... Si ₃ N ₄ film, 5... conductive turntable,
6... Conductive head, 7... Recording signal voltage, 8... Depletion layer, 9... Metal film pattern.

Claims (1)

[Claims] 1. Rotating a disk-shaped recording medium in which an insulating film having a charge accumulation function is formed on a semiconductor substrate,
In the apparatus for recording and reproducing signals by bringing a conductive head into contact with the surface of the insulating film, a metal film pattern having a sawtooth shape along the circumferential direction of the recording medium is provided on the peripheral part of the surface of the insulating film. form,
Signal recording and reproducing characterized in that a change in light reflectance due to the metal film pattern or a change in electrical characteristics in the thickness direction of the recording medium is detected, and the detected signal is used as a control signal during the recording or reproduction. Device.