JPS6214895B2 - - 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.

FIG. 1 shows an outline of a signal recording and reproducing apparatus of this type, and is an example in which the recording medium has an NOS structure. That is, the recording medium 1 has a SiO ₂ film 3 of several tens of angstroms thick and an Si ₃ N ₄ film 4 of several hundred angstroms thick as an insulating film having a charge storage function on a semiconductor substrate 2 such as a Si substrate. The semiconductor substrate 2 is laminated and formed into a circular disk shape as a whole, and is placed and fixed on a circular conductive turntable 5 with the back surface of the semiconductor substrate 2 facing down.

During signal recording, the tip of the conductive head 5, which has a thin electrode 5b formed on the side surface of an insulating substrate 5a 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 signal recorded in this way, the conductive head 6 is brought into contact with the surface of the Si ₃ N ₄ film 4, and while it is relatively moved along the recording track, the depletion is transmitted through the head 6. This is done by detecting the change in capacitance in the thickness direction of the recording medium 1 due to the 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, in the above case, the conductive turntable 5
The recording medium 1 is fixed onto the turntable 5 by mechanical means, adhesive, or an air chuck, but in this case it is inevitable that the gap between the recording medium 1 and the turntable 5 will be uneven.
As a result, the electric field distribution due to the recording signal voltage 7 is affected by the non-uniformity of the gap, making it impossible to perform recording with good reproducibility. Also, this non-uniformity of the gap naturally affects the detection of capacitance during playback, and therefore the S/N
It becomes difficult to perform good and correct reproduction.

An object of the present invention is to achieve good recording without being affected by uneven gaps between a recording medium using a semiconductor and a conductive turntable on which it is placed and fixed.
It is an object of the present invention to provide a signal recording and reproducing device capable of performing reproduction.

In order to achieve the above object, the present invention rotates a disk-shaped recording medium in which an insulating film having a charge storage function is formed on a semiconductor substrate, and records signals by bringing a conductive head into contact with the surface of the insulating film. and a device for reproducing, in which the recording medium is mounted and fixed on a conductive turntable and rotated during recording and reproduction of the signal, and a conductive material film is provided on the surface of the semiconductor substrate on the conductive turntable side. Alternatively, it is characterized by forming a low resistance film.

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 conductive film 9, such as an aluminum film, is formed on the back surface of the semiconductor substrate 2 of the recording medium 1 by vapor deposition, sputtering, ion plating, or other methods. Then, the recording medium 1 is placed on the conductive turntable 5 with the conductive film 9 facing downward, and fixed by a metal fitting 10, an adhesive, or an air check. The turntable 5 is rotationally driven by a motor. During signal recording, the conductive head 6 and the turntable 5 move relative to the recording medium 1 as the turntable 5 rotates.
A recording signal voltage 7 is applied between them, and a reproducing circuit using a capacitance detection method is connected between them during signal reproduction.

In this way, the turntable 5 on the semiconductor substrate 2
By forming the conductive film 9 on the side surface, even if the gap between the recording medium 1 and the turntable 5 is uneven, the back surface of the semiconductor substrate 2 is kept at the same potential, so that the recording signal The electric field distribution within the recording medium 1 due to the voltage 7 is not affected by the non-uniformity of the gap. Therefore, good recording with high reproducibility can be performed. Further, even during reproduction, the electrostatic capacitance detected by the reproduction circuit is less affected by the non-uniformity of the gap, making it possible to perform good reproduction.

Further, according to the present invention, since a conductive material is used as the turntable 5, it is possible to ensure electrical connection between the recording medium 1 and the recording or reproducing circuit through the conductive head 6 and the conductive turntable 5. can. That is, assuming that the turntable is non-conductive, in order to achieve electrical connection between the conductive film 9 and the recording/reproducing circuit during recording and reproduction, it is necessary to contact the conductive film 9 with a slip ring or the like. However, if the turntable 5 is conductive, the turntable is normally connected to the housing and held at ground potential, so the slip ring Electrical connection between the conductive film 9 and the recording/reproducing circuit can be easily obtained without using such complicated means.

Note that even if the conductive film 9 is a low-resistance film whose electrical resistance is sufficiently lower than that of the semiconductor substrate 2, the same effect can be obtained.

FIG. 3 shows another embodiment of the invention. In this embodiment, the turntable 5 is formed in a convex shape, and only the central portion 9a of the conductor film 9 is in contact with the turntable 5. As long as the conductive film 9 is formed sufficiently thick, even if the conductive film 9 partially contacts the turntable 5 like this, there is no problem in terms of strength or the like. The peripheral portion 9b of the conductor film 9 is patterned into a specific pattern, for example, a sawtooth pattern, by photoetching or the like. Photodetector 11
detects the pattern of the peripheral portion 9b of the conductor film 9 as a change in light reflectance to obtain a detection signal. Therefore, by using this detection signal, various controls such as servo control of the rotational speed of the recording medium 1, determination of the first track position to be recorded during recording, search for the first recorded track, tracking control, etc. can be performed. can be done.

[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 one embodiment of the invention, and Figs. 3a and b are other embodiments of the invention. FIG. 2 is a cross-sectional view and a plan view of a main part of an example. 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... Conductor film (low resistance body membranes).

Claims (1)

[Claims] 1. Rotating a disk-shaped recording medium in which an insulating film having a charge storage function is formed on a semiconductor substrate,
In the device for recording and reproducing signals by bringing a conductive head into contact with the surface of the insulating film, the recording medium is mounted and fixed on a conductive turntable and rotated when recording and reproducing the signal, and A signal recording/reproducing device characterized in that a conductive film or a low resistance film is formed on the surface of the semiconductor substrate on the conductive turntable side.