JP2715070B2 - Auto tracking mechanism - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auto-tracking mechanism that can be used, for example, in a recording / reproducing apparatus using an electron beam and guides the electron beam accurately on a tracking pattern. . 2. Description of the Related Art In a recording / reproducing apparatus using an electron beam, high-density recording / reproduction is performed when an electron beam emitted from an electron beam source is focused via an electromagnetic lens and a converging lens and reaches a recording medium. In order to execute with a high signal-to-noise ratio (S / N ratio), a high-precision tracking technique is required to always make the focusing position of the electron beam coincide with the information recording position on the recording medium. In particular, in a system that simultaneously records and reproduces data in parallel using a large number of electron beams, a large number of electron beams must be accurately focused at the recording position corresponding to each electron beam at the same time. However, no suitable method for this has been found at present. [Object of the Invention] An object of the present invention is to provide an automatic tracking mechanism capable of accurately guiding an electron beam on a tracking pattern. [Summary of the Invention] The gist of the present invention for achieving the above object is an auto-tracking mechanism for tracking an electron beam on a tracking pattern provided on a surface to be irradiated with the electron beam, wherein the electron beam is A detector for detecting secondary electrons generated by being irradiated on the tracking pattern, and control means for controlling an irradiation position of the electron beam based on the amount of the detected secondary electrons, wherein the tracking pattern is An auto-tracking mechanism characterized in that a material having an edge portion at both ends and having a concave or convex cross-section and a material that generates more secondary electrons due to irradiation of an electron beam than the other portion is used for the edge portion. It is. [Embodiment of the Invention] The present invention will be described in detail based on the illustrated embodiment. FIG. 1 is a configuration diagram of an electron beam recording / reproducing apparatus. 1
Is a flat recording medium having a portion to be recorded by an electron beam on the upper surface thereof, and a groove 2 for detecting an auto-tracking signal formed by etching or the like. Above the recording medium 1, a solid-state electron beam head 3 for generating a large number of electron beams is arranged. On both sides between the electron beam head 3 and the recording medium 1, a focusing electron beam for focusing a plurality of electron beams is provided. An electromagnetic lens 4 and a deflecting electromagnetic lens 5 for deflecting the focused electron beam are provided. Reference numeral 6 denotes a signal processing unit from the recording medium 1, and 7 denotes a control unit 7 for electron beam deflection.
Controls the drive controller 9 of the deflecting electromagnetic lens 5 based on a signal from a detector 8 that detects secondary electrons generated when the electron beam is irradiated to the auto tracking signal detection groove 2. Has become. Reference numeral 10 denotes a drive control device for the focusing electromagnetic lens 4. In such a configuration, the electron beams emitted from the electron beam head 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 irradiates the auto tracking signal detection groove 2. The electron beam and the tracking signal detecting groove 2 correspond to FIG.
(A) indicates a state where tracking is achieved, and (b) indicates a state where tracking is not performed when the electron beam irradiates a position deviating from the tracking signal detecting groove 2 as illustrated in (b). And Generally, in a secondary electron image obtained by SEM (Scanning Electron Micrograph) observation, the amount of secondary electrons detected at the edge of a sample or at the corner of a convex portion increases, and a bright and bright edge effect is known. In the state of (a), secondary electrons are emitted not only from the surface but also from the side surfaces, so that the amount of detected secondary electrons is increased as compared with the state of (a). Therefore, the amount of secondary electron detection greatly differs depending on whether tracking is performed, and the signal from the electron detector 8 is fed back to the controller 7 and the drive electromagnetic controller 5 via the drive control device 9 to deflect the electron beam. If the deflection is adjusted so as to always be in the state (a), the remaining electron beams are also subjected to the same deflection as the tracking signal detection electron beam, so that all the electron beams exactly coincide with the respective recording positions. Can be. 3 (a) and 3 (b) show a reference example of the auto-tracking signal detecting groove 2, and FIG. 3 (c) shows an embodiment of the auto-tracking signal detecting groove 2. FIG. 3A shows a groove 2 dug in the surface of the recording medium 1 by etching or the like. In FIG. 3 (b), a substance 11 having a higher secondary electron emission efficiency with respect to the electron beam irradiation than the surface of the recording medium 1 is formed on the inner surface of the groove 2 as in FIG. Coated. When the groove 2 shown in FIG. 3B is used, the amount of secondary electrons emitted over the entire inner surface of the groove 2 becomes larger than when the groove 2 shown in FIG. 3A is used.
A tracking signal having a high S / N ratio can be obtained. On the other hand, the auto-tracking signal detecting groove 2 shown in FIG. 3 (c), which is an embodiment of the present invention, has only the outer edge of the groove 2 coated with a substance 11 having a high secondary electron emission effect. In this case, the following effects can be obtained as compared with the above reference example. In other words, the amount of secondary electron emission is small when tracking is achieved as shown in FIG. 2, and the secondary electron emission effect is high when tracking is not achieved as shown in FIG. 2 (b). Since the substance 11 is irradiated with the electron beam, secondary electron emission is increased as compared with the case where the substance 11 is not used, and a tracking signal with a higher S / N ratio can be obtained. In the above-described embodiment, the cross-sectional shape of the groove 2 is quadrangular, but any shape such as a semicircular cross-section, a semi-elliptical shape, and a triangular shape 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 is larger than that of the inner and outer flat portions of the groove 2, so that whatever cross-sectional shape is used. The same effect can be obtained even if the same is performed. Further, the edge portion may be a convex end portion as shown in FIG. That is, the amount of secondary electrons detected when the upper surface of the convex portion 12 is irradiated with the electron beam instead of the groove 2, and the amount of secondary electrons detected when the edge of the convex portion 12 is irradiated with the electron beam. May be used as a tracking signal. In this case, the projection 12 may be formed by etching, or may be formed by bonding materials 13 having different secondary electron emission rates as shown in FIG. 4 (b), or by forming a thin film. And as in the case of FIG. 3 (c).
A tracking signal with a high S / N ratio can be obtained. According to the auto-tracking mechanism of the present embodiment, in the high-density recording method using a solid-state electron beam, one electron beam is used for detecting a tracking signal, so that the focusing and deflection electromagnetic lenses are controlled and the other The position of the electron beam for recording / reproducing can always be accurately matched with each recording medium line or spot,
Since an electron beam is used, the accuracy is good. Further, since secondary electron detection is used, a tracking signal having a high S / N ratio can be obtained. [Effect of the Invention] In the above description, the configuration in which the auto-tracking mechanism of the present invention is applied to the recording / reproducing apparatus using the electron beam has been described. It has an edge and its cross section is concave or convex, and the edge is made of a material that generates more secondary electrons due to electron beam irradiation than other parts, so tracking control with a high S / N ratio is used. A signal can be obtained, whereby accurate tracking can be realized. Also, if this auto-tracking mechanism is used in a recording / reproducing apparatus using an electron beam, the recording / reproducing electron beam can be controlled by a tracking signal, so that the recording position can be accurately irradiated with the recording / reproducing electron beam. it can.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of an auto-tracking mechanism according to the present invention. FIG. 1 is a block diagram of the electron beam recording / reproducing apparatus, and FIG. FIG. 3 is a cross-sectional view of a groove for auto-tracking in a state where the electron beam is irradiated, FIG. 4 is a cross-sectional view of a protrusion for auto-tracking, and FIG. Reference numeral 1 denotes a recording medium, 2 denotes an auto tracking signal detection groove, 3 denotes a solid-state electron beam generator, 4 denotes a focusing electromagnetic lens, 5 denotes a deflection electromagnetic lens, 6 denotes a signal processing unit, 7 denotes a control unit, and 8 denotes a control unit. Secondary electron detectors 9, 9 and 10 are drive control devices, and 11 is an auto tracking signal detecting projection.

Continuation of front page    (72) Inventor Yukio Masuda               3-30-2 Shimomaruko, Ota-ku, Tokyo               Inside Canon Inc. (72) Inventor Nobutoshi Mizusawa               3-30-2 Shimomaruko, Ota-ku, Tokyo               Inside Canon Inc. (72) Inventor Hitoshi Oda               3-30-2 Shimomaruko, Ota-ku, Tokyo               Inside Canon Inc.                (56) References JP-A-60-29953 (JP, A)                 JP-A-60-29952 (JP, A)                 52-44702 (JP, U)

Claims (1)

(57) [Claims] An auto-tracking mechanism that tracks an electron beam on a tracking pattern provided on a surface to be irradiated with the electron beam, and a detector that detects secondary electrons generated by irradiating the tracking pattern with the electron beam. Control means for controlling the irradiation position of the electron beam based on the detected amount of secondary electrons, wherein the tracking pattern has an edge portion at both ends and has a concave or convex cross section, and the edge portion An auto-tracking mechanism characterized by using a material that generates more secondary electrons due to electron beam irradiation than other parts.