JP2007033486A - Cartridge type hologram recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To widen the aperture of a cartridge chassis for an optical pickup to access a hologram recording material so that an opening/closing mechanism to slide a cover works and an optical system is not brought into contact with the cartridge chassis. <P>SOLUTION: The aperture 10 enabling a signal light optical system (lens barrel 306) and a reference light optical system (lens barrel 307) to access a hologram recording material 202 is placed at a position rendering the aperture into asymmetry with respect to the center line of a cartridge chassis 201. The aperture is opened by moving a cover (not shown in figure) to a side where the aperture 10 possesses less area, which means that the cover can be housed without protruding from the front face of the cartridge chassis 201 even when the width of the aperture 10 is increased, and that the opening/closing mechanism to slide the cover can be mounted. Since the aperture 10 is wide, the tip of the signal light optical system can be inserted into the aperture 10. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hologram recording / reproducing apparatus, and more particularly to an opening of a cartridge type hologram recording medium in which a hologram recording material is housed in a cartridge housing in order to prevent unnecessary exposure due to external light.

  In recent years, holographic technology has been rapidly developed for the practical application of holographic memory, which is attracting attention as a powerful storage candidate competing with next-generation and next-generation optical discs. A hologram recording / reproducing system for recording / reproducing a large amount of data has been proposed.

  The hologram recording apparatus that has been attracting attention in this way is often used mainly for photopolymers as a recording medium in its practical application. When this photopolymer is used, it has photosensitivity, so it must not be exposed to external light until exposure and subsequent fixing processing. Put in and store. In general, it is inserted into the apparatus while being put in a case, and the shutter of the case is opened to expose from there.

  In the case of a hologram recording apparatus, unlike other optical recording methods, the target is a two-dimensional data pattern, and therefore the spot diameter is increased, the spatial modulator size, the laser output, Due to problems such as avoiding each aberration, the objective lens becomes large. Since the objective lens becomes large, it is necessary to enlarge the opening of the cartridge as compared with the conventional optical recording method and other optical recording methods under development. On the other hand, a magneto-optical disk (hereinafter referred to as MO) is provided with a magnetic head for recording and erasing in addition to the objective lens, as compared with other optical recording systems, and a correspondingly large opening is required. Therefore, in hologram recording, recording is generally performed using an MO cartridge or using a similar cartridge (see, for example, Patent Document 1).

  Incidentally, in order to further improve the recording density in hologram recording, it is necessary to shorten the distance between the objective lens and the recording medium and reduce the spot diameter of the recording signal light. In order to bring the objective lens closer, it is necessary to open the cartridge wider. If the opening of the cartridge is further expanded, the strength of the cartridge may not be sufficient, and the cover mechanism using the slide may not fit within the entire surface of the cartridge.

  FIG. 8 is a plan view showing a configuration example of a conventional cartridge type hologram recording medium. The disc-shaped hologram recording material 202 is stored in a light-shielding cartridge housing 201, and a cover (shutter) 203 that slides sideways is attached to the front surface of the cartridge housing 201, and is closed in the drawing. When the cover 203 is slid sideways as shown in FIG. 9, the cover 203 is opened, and a part of the hologram recording material 202 inside is exposed, and data can be recorded and reproduced. As described above, since the cover 203 has a mechanism that slides sideways, the width of the cover 203 must be equal to or less than one third of the width of the front surface of the cartridge housing 201. In addition, from the viewpoint of using the slide type and from the viewpoint of double-sided recording, the opening has a symmetrical shape, and some models have a mechanism that slides to either side. In the case of angle-multiplexed hologram recording, the reference light and signal light need to be incident at a certain angle rather than perpendicular to the hologram recording material 202, so a wider opening is required.

FIG. 10 is a cross-sectional view showing a case where angle multiplex recording is performed using a conventional cartridge type hologram recording medium, and shows a state in which a part of the hologram recording material inside is exposed with the cover opened. ing. In the case of angle multiplexing hologram recording, the signal light 301 passes through the objective lens 302 and reaches the hologram recording material 202. On the other hand, the reference beam 303 reaches the hologram recording material 202 through lenses 304 and 305 for changing the angle of the reference beam. As a result, the signal light 301 and the reference light 303 interfere inside the hologram recording material 202, and the interference fringes are recorded.
Utility Model Registration Gazette No. 2520275 (page 3-5, Fig. 1)

However, when data is recorded on the cartridge-type hologram recording medium by the angle multiplexing method, the signal light 301 and the reference light 303 are irradiated to the hologram recording material 202 from an oblique direction. It will be very close to 201. Therefore, the lens barrels 306 and 307 holding the lens 302 and the lens 305 may come into contact with the cartridge housing 201. Therefore, if the opening of the cartridge housing 201 is unnecessarily widened so that the lens barrels 306 and 307 do not contact the cartridge housing 201, the following inconvenience occurs in addition to the problem that the strength is lowered. (1) When the opening becomes wider, the width of the cover 203 covering the opening becomes wider. If the cover 203 is wide, the end of the cover 203 protrudes from the front surface of the cartridge housing 201 when the cover 203 is opened, and a spring mechanism or the like for closing the cover 203 cannot be installed. The slide opening / closing mechanism is no longer valid.
(2) If the opening is wide, the cover 203 cannot be moved to an appropriate position. When the signal light 301 or the reference light 303 is reflected on the surface of the hologram material 202, the reflected light hits the inner surface of the cover 203 and is reflected. The reflected light thus diffused inside the cartridge housing 201, which may cause noise in the recording data.

  The present invention has been devised in view of the above circumstances, and an object of the present invention is to widen the opening so that an opening / closing mechanism for sliding the cover is established and the optical system does not contact the cartridge housing. Another object of the present invention is to provide a cartridge type hologram recording medium that can be used.

  In order to achieve the above object, the present invention is a cartridge-type hologram recording medium in which a hologram recording material for recording interference fringes of two light beams is housed in a cartridge housing, and the two light beams are irradiated onto the hologram recording material. The first opening that is accessed by the optical pickup is provided at a position that is asymmetric with respect to the center line of the cartridge housing on the front surface of the cartridge housing, and a cover that opens and closes the opening is provided. Features.

  Further, the present invention provides the hologram recording material to the outside by opening the opening by moving the cover to the side where the area occupied by the first opening is small with respect to the center line of the cartridge housing. It is exposed.

  Further, the present invention is characterized in that either one or both of the tip of the signal light optical system and the tip of the reference light optical system constituting the pickup enter the first opening. .

  As described above, in the cartridge type hologram recording medium of the present invention, the cover is provided in the cartridge by providing the opening for the optical pickup to access the hologram recording material at a position that is asymmetric with respect to the center line of the cartridge housing. Since the opening is opened by moving the first opening to the side where the area occupied by the first opening is small with respect to the center line of the housing, the cover can be placed on the front surface of the cartridge housing even if the width of the opening is widened. It can be stored without protruding, and an opening / closing mechanism for sliding the cover can be attached. In addition, since the width of the opening is wide, the tip of the signal light optical system or the tip of the reference light optical system constituting the pickup can be inserted into the opening, especially when recording with the angle multiplexing method. It is possible to increase the swing angle of light and improve the recording density. Also, if the opening is wide, the exposure of the hologram recording material can be increased, and the objective lens can be brought closer to the hologram recording material, and the objective lens of the recording / reproducing optical system can be brought closer to the recording medium. Thus, the NA of the recording / reproducing optical system can be increased. Therefore, it is possible to increase the recording density on the recording medium for recording.

According to the present invention, in the cartridge-type hologram recording medium, the opening for allowing the optical pickup to access the hologram recording material is provided at a position that is asymmetric with respect to the center line of the cartridge housing, whereby the cover is opened and closed. The size of the opening can be increased so that the mechanism is established and the optical system does not contact the cartridge housing.
As a result, when recording by the angle multiplexing method, the swing angle of the reference light can be increased and the recording density can be improved. Also, if the opening is wide, the exposure of the hologram recording material can be increased and the objective lens can be brought closer to the hologram recording material, and the NA of the recording / reproducing system can be increased.
Further, since the opening is asymmetric with respect to the center line of the cartridge housing, the lack of strength of the cartridge can be solved as an adverse effect of simply widening the opening.
Further, by gradually moving the degree of opening of the cover in accordance with the angle of the reference light, it becomes possible to absorb the reflection of the signal light on the surface of the recording material, thereby suppressing excessive noise.

  For the purpose of increasing the size of the opening for the optical system to access the hologram recording material so that the opening / closing mechanism for sliding the cover is established and the optical system is not in contact with the cartridge housing, the opening is made into a cartridge. This was realized by providing a position that is asymmetric with respect to the center line of the housing.

  FIG. 1 is a plan view showing a configuration of a cartridge type hologram recording medium according to the first embodiment of the present invention. The cartridge type hologram recording medium is configured by housing a disc-shaped hologram recording material 202 in a cartridge housing 201, and a cover 203 covering the opening 10 provided in the cartridge housing 201 is slidably attached.

  Next, the recording operation of the present embodiment will be described with reference to FIG. 2. FIG. 2 is a cross-sectional view showing a state in which data is recorded using a cartridge type hologram recording medium. The signal light 301 is applied to the hologram recording material 202 through the lens 302, the reference light 303 is applied to the hologram recording material 202 through the lenses 304 and 305, and interference fringes of both lights are recorded on the hologram recording material 202. When holographic recording is performed by the angle multiplexing method, the signal light 301 and the reference light 303 are irradiated to the hologram recording material 202 from an oblique direction, so that the lens 302 and the lens 305 are extremely close to the cartridge housing 201. Become.

  Therefore, there is a possibility that a part of the lens barrels 306 and 307 holding the lens 302 and the lens 305 may come into contact with the cartridge housing 201. In this embodiment, the opening 10 is a hologram recording material in the cartridge housing 201. Since the center line O that coincides with the radius line 202 is shifted to the right side and the width of the opening 10 is wider than before, a part of the lens barrel 306 of the signal light optical system is opened. The inside of the unit 10 is in a state where it does not come into contact with the cartridge housing 201. On the other hand, since the lens barrel 307 of the reference light optical system still has room for the cartridge housing 201, it is not necessary to open it. Therefore, the opening shape of the cartridge is not symmetrical with respect to the center line O, and the cover 203 is slid to the left side where the area occupied by the opening portion 10 is narrow, and the hologram recording material 202 as shown in FIG. It is supposed to be exposed. As a result, the cover 203 does not protrude from the front surface of the cartridge housing 201 even though the opening 10 is widened.

  According to the present embodiment, the opening 10 provided in the cartridge housing 201 is widened and asymmetric with respect to the center line O, so that the signal light 301 and the reference light 303 are irradiated obliquely as necessary. And the recording density of angle-multiplexed hologram recording can be increased.

  Further, the cover 203 is slid in the direction in which the area occupied by the opening 10 is narrow, so that the slide mechanism of the cover 203 can be installed without protruding from the front surface of the cartridge housing 201. Further, since the position where the opening 10 is disposed is asymmetric with respect to the center line O, it is possible to reduce the strength of the cartridge casing 201 from being impaired.

  Furthermore, if the opening 10 is wide, the exposure of the hologram recording material 202 can be increased, and the objective lens 302 can be brought closer to the hologram recording material 202, and the NA of the recording / reproducing system can be increased.

  When a part of the cover 203 protrudes from the front surface of the cartridge casing 201 when the cover 203 is opened, only a stopper for temporarily fixing the open position and the closed position of the cover 203 is provided. A mechanism for sliding the cover 203 to open and close may be provided on the hologram recording / reproducing apparatus side.

  FIG. 4 is a plan view showing a configuration of a cartridge type hologram recording medium according to the second embodiment of the present invention. In the present embodiment, a state in which the reflection type hologram recording material 202 stored in the cartridge housing 201 is reproduced is shown, and the openings 10 (opening portions on the back surface) are respectively formed on the front surface and the back surface of the cartridge housing 201. 5 is provided, and a cover 203 (see FIG. 6 for the back cover 204) that covers each opening is slidable.

  Next, the operation of this embodiment will be described with reference to FIG. When the reflection type hologram recording material 202 is used, the front cover 203 slides to the left and the back cover 204 slides to the right during reproduction, and the reflection hologram recording material 202 is exposed as shown in FIG. In FIG. 5, reference light 303 is irradiated from the front surface of the hologram recording material 202 through lenses 304 and 305 to generate reproduction light 601. The reproduction light 601 is incident on an imaging element (not shown) through the Fourier lens 602 from the back surface of the reflective hologram recording material 202 to reproduce data.

  In the case of the present embodiment, since the opening 10 and the opening 11 are arranged on the front surface and the back surface of the cartridge housing 201 in accordance with the position of the optical system used at the time of recording and reproduction, particularly the reproduction light 601 is used. Even if the reproducing light optical system (lens barrel 603) is close to the hologram recording material 202 from an angle as much as necessary for picking up, it does not come into contact with the cartridge housing 201, and the swing angle during recording is increased accordingly. And the recording density of angle-multiplexed hologram recording can be increased. Since the opening 10 and the opening 11 are separately provided on the front surface and the back surface of the cartridge housing 201, the sliding directions of the covers 203 and 204 for opening and closing these openings may be opposite directions. And can be smoothly opened and closed by attaching a slide mechanism.

  When the cover 204 attached to the back surface of the cartridge housing 201 is opened and a part of the cover 204 protrudes from the front surface of the cartridge housing 201 as shown in FIG. 6, the cover 204 is opened and closed. Only a stopper for temporarily fixing the position may be provided, and a mechanism for sliding the cover 204 to open and close may be provided on the hologram recording / reproducing apparatus side.

  FIG. 7 is a side view showing the configuration of a cartridge type hologram recording medium according to the third embodiment of the present invention. This embodiment is almost the same as the second embodiment, but the cover 203 is gradually opened according to the incident angle of the reference light 303 to the hologram recording material 202. In other words, the cover 203 is moved in accordance with the swing angle of the reference light 303 so as not to block the reference light 303. Thereby, the reflected light 801 of the reference light 303 is shielded by the inner wall of the cover 203. The inner wall of the cover 203 has a physical shape that absorbs the reference light, or is subjected to chemical treatment to absorb the reflection, and excess light is scattered inside the cartridge housing 201 to cause recording. Noise can be prevented. Other effects are the same as those of the second embodiment.

  In addition, this invention is not limited to the said embodiment, In the range which does not deviate from the summary, it can implement also with another various form in a concrete structure, a function, an effect | action, and an effect.

1 is a plan view showing a configuration of a cartridge type hologram recording medium according to a first embodiment of the present invention. It is sectional drawing which showed a mode that data was recorded using the cartridge type hologram recording medium shown in FIG. It is the top view which showed the state which opened the cover shown in FIG. It is the top view which showed the structure of the cartridge type hologram recording medium which concerns on the 2nd Embodiment of this invention. FIG. 5 is a cross-sectional view showing a state in which data is recorded using the cartridge type hologram recording medium shown in FIG. 4. FIG. 6 is a plan view showing a case where a cover protrudes from the cartridge housing. It is the side view which showed the structure of the cartridge type hologram recording medium which concerns on the 3rd Embodiment of this invention. It is the top view which showed the structural example of the conventional cartridge type hologram recording medium. It is the top view which showed the state which opened the cover shown in FIG. It is sectional drawing which showed the case where angle multiplex recording is performed using the conventional cartridge type hologram recording medium.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10, 11 ... Opening part, 201 ... Cartridge housing, 202 ... Hologram recording material, 203, 204 ... Cover, 302, 304, 305, 602 ... Lens, 306, 307, 603 ... Lens barrel.

Claims (8)

A cartridge-type hologram recording medium in which a hologram recording material for recording interference fringes of two light beams is housed in a cartridge housing,
A first opening that is accessed by an optical pickup that irradiates the hologram recording material with the two light beams is provided at a position that is asymmetrical with respect to a center line of the cartridge case on the front surface of the cartridge case; A cartridge-type hologram recording medium comprising a cover for opening and closing an opening.   The hologram recording material is exposed to the outside by opening the opening by moving the cover to a side where the area occupied by the first opening is small with respect to the center line of the cartridge housing. The cartridge-type hologram recording medium according to claim 1.   When the cover is moved and the first opening is opened, if the cover protrudes from the front surface of the cartridge housing, only a stopper for temporarily fixing the open position and the closed position of the cover is provided. The cartridge-type hologram recording medium according to claim 1 or 2, wherein   4. One of the front end of the signal light optical system and the front end of the reference light optical system constituting the pickup, or a part of both, penetrates into the first opening. A cartridge-type hologram recording medium according to claim 1.   The hologram recording material is a reflection type, and a reproducing optical system tip that receives reproduction light generated from the hologram recording material and guides it to an image pickup device at the time of reproducing interference fringes recorded on the hologram recording material is the hologram recording material 5. The cartridge according to claim 1, wherein a second opening for accessing the cartridge is provided on a back surface of the cartridge housing, and a cover for opening and closing the opening is provided. Type hologram recording medium.   6. The cartridge-type hologram recording medium according to claim 5, wherein the second opening is provided asymmetrically with respect to the center line of the cartridge casing.   The hologram recording material is exposed to the outside by opening the opening by moving the cover to the side where the area occupied by the second opening is small with respect to the center line of the cartridge housing. The cartridge-type hologram recording medium according to claim 6.   When the cover is moved and the second opening is opened, if the cover protrudes from the front surface of the cartridge housing, only a stopper for temporarily fixing the open position and the closed position of the cover is provided. The cartridge-type hologram recording medium according to claim 6 or 7,

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