JPS6355744A - Auto-tracking mechanism - Google Patents

Abstract

PURPOSE:To use one electron beam for detecting a tracking signal and to precisely converge the other electron beams in their recording positions in terms of a recording and reproducing device employing a host of electron beams. CONSTITUTION:Among plural electron beams coming out of an electron beam head 3, one is used for detecting the tracking signal and projected on an autotracking detection groove 2. A secondary electron detector 8 detects the intensity of a secondary electron generated in the groove 2. A signal from the detector 8 is fed back. A deflecting electromagnetic lens 5 adjusts the deflection of the electron beam concerned, and attains a state where tracking is removed. Thus the remaining electron beams are deflected as the same as the beam for detecting the tracking signal, and therefore all the electron beams can be precisely recorded in their recording positions.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an auto-tracking mechanism in a recording/reproducing apparatus using an electron beam.

[Prior Art] In a recording/reproducing device using an electron beam, when the electron beam emitted from an electron beam generation source passes through an electromagnetic lens and a converging lens and is focused on a recording medium, high-density recording reproduction is performed. In order to perform with a high signal-to-noise ratio (S/N ratio), a highly accurate tracking technique is required to always align the focused position of the electron beam with the information recording position on the recording medium. In particular, in a system that uses multiple electron beams to play back records simultaneously in parallel, it is necessary to accurately focus the multiple electron beams on the recording position corresponding to each electron beam at the same time, and a more precise auto-tracking mechanism is required. is required, but no suitable method has been found at present.

[Object of the Invention] An object of the present invention is to use one electron beam for tracking signal detection in a recording and reproducing apparatus using a large number of electron beams, and to send all other electron beams to each recording point. The object of the present invention is to provide an auto-tracking mechanism that allows accurate focusing.

[Summary of the Invention] The gist of the present invention for achieving the above-mentioned object is to provide a recording/reproducing apparatus having an electron beam head that outputs a large number of electron beams, in which the electron beams are applied to a tracking pattern portion formed on a recording medium. This is an auto-tracking mechanism characterized in that one of the electron beams is irradiated, and the intensity of the secondary electrons generated from the pattern portion is detected by a detector and used as a tracking signal.

[Embodiments of the invention] The present invention will be explained in detail based on illustrated embodiments.

FIG. 1 is a block diagram of an electron beam recording/reproducing apparatus. Reference numeral 1 denotes a flat recording medium, which has a portion recorded by an electron beam on its upper surface, and is further provided with a groove 2 for detecting an auto-tracking signal formed by etching or the like. Further, a solid-state electron beam head 3 that generates a large number of electron beams is arranged above the recording medium 1, and a focusing head 3 for focusing the plurality of electron beams is placed on both sides between the electron beam head 3 and the recording medium 1. A deflection electromagnetic lens 4 and a deflection electromagnetic lens 5 for deflecting the focused electron beam are provided. Note that 6 is a signal processing unit from the recording medium 1;
7 is a control unit 7 for electron beam deflection, and the control unit 7 is based on a signal from a detector 8 that detects secondary electrons generated when the auto-tracking signal detection groove 2 is irradiated with an electron beam. In addition, a drive control device 9 for the deflection electromagnetic lens 5 is controlled. Note that 10 is a focusing electromagnetic device and a drive control device for the lens 4.

In such a configuration, the electron beams emitted from the RAD 3 are respectively focused by the focusing electromagnetic lens 4, and further deflected by the deflection electromagnetic lens 5 toward a desired recording position. One of the electron beams is used exclusively for tracking signal detection, and is designed to irradiate the auto-tracking signal detection groove 2. Tracking is achieved when the electron beam and the tracking signal detection groove 2 are in the relationship as shown in FIG. 2(a), and as shown in FIG. A state in which tracking is not achieved is when a position outside of 2 is irradiated.

Generally, SEM (Scanning Electr
In secondary electron images observed in on nicrographs, it is known that there is an edge effect in which the amount of secondary electrons detected increases at the edges of the sample or at the corners of convex parts, causing them to shine brightly.
In state b), secondary electrons are emitted not only from the surface but also from the side surfaces, so the amount of detected secondary electrons is increased compared to state (a). Therefore, the amount of secondary electrons detected varies greatly depending on whether tracking is achieved or not, and the signal from the electron detector 8 is fed back to control @! &7. If the deflection of the electron beam is adjusted by the deflection electromagnetic lens 5 via the drive control device 9 so that it is always in the state (a), the remaining electron beams will have exactly the same deflection as the tracking signal detection electron beam. Therefore, all electron beams can be precisely aligned with each recording position.

FIG. 3 shows several forms of the auto-tracking signal detection groove 2. FIG. 3(a) shows the groove 2 dug on the surface of the recording medium 1 by etching or the like. Figure 3 (b
), the recording medium 1 is placed on the inner surface of the groove 2 similar to (a).
A substance 11 having a higher secondary electron emission efficiency than the surface of the substrate 11 when irradiated with an electron beam is coated using a vapor deposition method or a sputtering method. When the groove 2 shown in FIG. 3(b) is used, the amount of secondary electrons emitted over the entire interior of the groove 2 is larger than when the groove 2 shown in FIG. 3(a) is used, so the S/ A tracking signal with a high N ratio can be obtained. Furthermore, Figure 3 (
The auto tracking signal detection groove 2 shown in C) is the groove 2.
Substance 11 that has a high secondary electron emission effect only at the outer edges of
Of course, the same effect can be obtained in this case as well.

That is, in a state where tracking is achieved as shown in Figure 2, secondary electron emission 2 is small, and when tracking is not achieved as shown in Figure 2(b), the material has a high secondary electron emission effect. Since the material 11 is irradiated with the electron beam, the amount of secondary electrons emitted is greater than when the material 11 is not used, and a tracking signal with a higher S/N ratio can be obtained.

Further, in the above embodiment, the groove 2 has a rectangular cross-sectional shape, but any cross-sectional shape such as a semicircular, semielliptical, triangular, etc. can be used. In other words, if the end of the groove 2 has an extremely sharp shape, the amount of secondary electrons emitted at that end will be greater than the flat parts inside and outside of the groove 2, so any cross-sectional shape can be used. The same effect can be obtained.

Furthermore, this edge portion may be a convex end as shown in FIG. The difference between the amount of secondary electrons and the amount of secondary electrons detected when the edges of the convex portions 12 are irradiated can be used as a tracking signal.In this case, the convex portions 12 are formed by etching. Alternatively, materials 13 with different secondary electron emission rates may be bonded together as shown in Figure 34(b), or 'f
It may be formed as a fli, and a tracking signal with a high S/N ratio can be obtained as in the case of FIG.

[Effects of the Invention] As explained above, according to the auto-tracking mechanism according to the present invention, one electron beam can be used for tracking signal detection in a high-density recording method using a solid-state electron beam, so that it can be used for focusing, deflection, etc. By controlling the electromagnetic lens for recording and reproducing, the position of the remaining recording and reproducing electron beams can always be accurately aligned with each recording medium line or spot. In addition, since secondary electron detection is used, S/
A tracking signal with a high N ratio can be obtained.

[Brief explanation of drawings]

The drawings show an embodiment of the auto-tracking mechanism according to the present invention, and FIG. 1 is a configuration diagram of the electron beam recording/reproducing device, and FIG. 2 shows an auto-tracking signal detection groove irradiated with an electron beam. 3 is a sectional view of the auto-tracking groove, and FIG. 4 is a sectional view of the auto-tracking convex portion. 1 is a recording medium, 2 is an auto-tracking signal detection groove, 3 is a solid-state electron beam generator, 4 is a focusing electromagnetic lens, 5 is a deflection electromagnetic lens, 6 is a signal processing section, 7 is a control section, and 8 is a Secondary electron detector. 9.10 is a drive control device, and 11 is a protrusion for detecting an auto-tracking signal.

Claims (1)

[Scope of Claims] 1. In a recording/reproducing apparatus having an electron beam head that outputs a large number of electron beams, one of the electron beams is irradiated onto a tracking pattern portion formed on a recording medium; An auto-tracking mechanism characterized in that the intensity of secondary electrons generated from a pattern portion is detected by a detector and used as a tracking signal. 2. The auto-tracking mechanism according to claim 1, wherein the pattern portion is an end portion of a groove. 3. The auto-tracking mechanism according to claim 1, wherein the pattern portion has a convex end.