BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
FIG. 1 is a view illustrating an example of a configuration of a conventional hologram recording medium;
FIG. 2A is a view for illustrating a configuration of a hologram recording medium in accordance with an embodiment of the present invention;
FIG. 2B is a detailed view illustrating a part 2B in FIG. 2A;
FIGS. 3A to 3C are schematic views for explaining manufacturing steps of the hologram recording medium in accordance with the embodiment of the present invention;
FIGS. 4A to 4F are views for explaining steps of incorporating the hologram recording medium according to the embodiment of the present invention, into a cartridge;
FIG. 5A is a schematic view illustrating an external appearance of a hologram cartridge media according to an embodiment of the present invention;
FIG. 5B is a detailed view illustrating a part 5B in FIG. 5A;
FIG. 5C is a schematic view illustrating a rear surface of the cartridge media shown in FIG. 5A;
FIG. 6A is a schematic view illustrating a configuration of a hologram recording medium in accordance with another embodiment of the present invention; and
FIG. 6B is a plan view illustrating the hologram recording medium shown in FIG. 6A.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 2A is a view illustrating an external appearance of a hologram recording medium 20 according to an embodiment of the present invention, the hologram recording medium 20 shown in FIG. 2A is composed of a top substrate 21, a frame 22 a bottom substrate 23, and a hologram recording material 24 which is filled in a hologram recording material filling space defined by the above-mentioned components. The bottom substrate 23 has a size which is larger than the inner peripheral size of the frame 22 but not greater than the outer peripheral size of the latter. The top substrate 21 has a size which is slightly smaller than the inner peripheral size of the frame 22, and accordingly, it can be fitted in the frame 22. Further, as shown in FIG. 2B, notch portions are formed in the frame 22, respectively at four corners thereof, and define material trapping parts 221 in which the hologram recording material 24 is trapped after it is pressed by the top substrate 21 so as to be spread over the entire surface of the substrate. Since the material trapping parts 221 are filled therein with extra hologram recording material, the hologram recording material can be uniformly filled in a data recording zone (filling space) with substantially uniform thickness. These notch portions may be formed, irrespective of whether it pierces through the frame 22 from a top surface to a bottom surface of the latter or not, if they can serve as places into which the extra hologram material escapes.
It is noted that the material trapping parts 221 are formed in the rectangular hologram recording medium 20 at four corners of the latter. However, the present invention should not be limited to this configuration, but they may be formed at two diagonal corners thereof or may be formed at any arbitrary position of four sides thereof (at least one side thereof).
Next, explanation will be made of process steps of manufacturing the hologram recording medium 20. FIGS. 3A to 3C are schematic views for explaining the manufacturing process steps of the hologram recording medium 20 having the configuration shown in FIGS. 2A to 2B.
Referring to FIG. 3A, at first, the frame 22 is set on the bottom substrate 23, and they are bonded to each other by means of an adhesive or the like. The frame 22 and the bottom substrate 23 may be integrally incorporated with each other. In this state, the hologram recording material 24 is filled in the frame 22 in a predetermined quantity (refer to FIG. 3B). Then, the hologram recording material 24 which is viscous is depressed and spread out by the top substrate 21 so that the hologram recording material 24 is uniformly widespread in the filling space (refer to FIG. 3C). It is noted that the filling quantity of the hologram recording material 24 is set to be slightly larger than a quantity required for forming a recording layer having a desired thickness in the recording material filling space defined by the top and bottom substrates 21, 23 and the frame 22. That is, a material which is surplus to the quantity required for forming the recording layer having a desired thickness, can escape into the material trapping parts 221 upon the depression of the top substrate 21. Accordingly, no delicate adjustment for the depressing pressure and the filling quantity of the hologram recording material 24 are required, and accordingly, the productivity of the hologram recording medium 20 can be enhanced. Further, in the recording material filling space, the hologram recording material for forming the recording layer has a thickness which may be substantially uniform (it is noted that the hologram recording material cannot have a precisely uniform thickness, and accordingly, the wording “substantially” is used. Thus, the wording should not be construed as such that the concept of the present invention is ambiguous). For example, if the thickness of the top and bottom substrates is set to 0.8 mm while the thickness of the recording medium is set to 1.5 mm, the thickness of the frame may be set to at least 2.3 (=1.5+0.8) mm.
The hologram recording medium 20 manufactured as stated above, is incorporated in a cartridge, and accordingly, a final product is obtained. FIGS. 4A to 4F are schematic views for explaining process steps of incorporating the hologram recording medium 20 into the cartridge.
Referring to FIGS. 4A to 4F, the hologram recording medium 20 is set in a cartridge base 31 having a window frame 311 in such a way that the bottom substrate 23 is fitted in the window frame 311. Further, in this state, a reflective and moisture-proof sealing film 32 is set on the top substrate 21 (refer to FIGS. 4C and 4D). In this condition in which the moisture-proof sealing film 32 is set, the cartridge cover 33 is laid over the film 32, and accordingly, a hologram cartridge media 30 is obtained as a final product (refer to FIGS. 4E and 4F). It is noted that the sealing film 32 may be further coated with a reflective film so as to have a function for reflecting a reference beam in such a case that the hologram recording media 30 is exclusively used as a ROM.
FIGS. 5A to 5C show an external appearance of the hologram cartridge media 30 manufactured as stated above. Referring to FIG. 5A which shows the front surface (recording surface) of the cartridge, recording and reproduction of information are carried out for the hologram recording medium 20 which is exposed from the window frame 311. That is, in a recoding and reproducing apparatus which is not shown, an interference pattern (interference fringes) which is formed through the interference between an information beam (two-dimensional data) and a reference beam is three-dimensionally formed in the hologram recording medium during information recording. Further, during information reproduction, the reference beam used for the information recording is irradiated onto the interference pattern so as to generate a reproduction beam which is then decoded for information reproduction.
As shown in FIG. 5B which is an enlarged view illustrating a part 5B in FIG. 5A, a notch 312 is formed in the cartridge base 31, with which the positioning of the hologram cartridge media 30 is carried out in a recording and reproducing apparatus (drive unit) which is not shown. Referring to FIG. 5C which shows the rear surface of the cartridge media, the cartridge cover 33 as shown is marked with an arrow (which may be integrally formed therewith) for indication of a direction of loading the hologram cartridge media 30 into the recording and reproducing apparatus. This arrow 331 exhibit such an advantage the user can prevent the cartridge media from being loaded in an erroneous direction.
Although explanation has been hereinabove made of the polygonal (rectangular) hologram recoding medium 20 in which the material trapping parts are formed, it is noted that the hologram recording medium 20 should not be limited to a rectangular shape in such a case that the recording capacity may be equal to the conventional one, that is, it may have a conventional disc shape. Referring to FIGS. 6A and 6B which are views illustrating a configuration of a disc shape hologram recording medium 40, at least one material trapping part 421 is formed in the inner peripheral part of the frame 42. With this configuration, even with the disc shape hologram recording medium, the hologram recording material (photopolymer material) which is viscous, may be filled so as to be uniformly spread into every corner of the substrates.
Further, in the embodiment shown in FIGS. 1 to 5C, there may be formed the hologram recording medium as follows: the frame 22 is integrally formed with or bonded to the cartage base 31, then, the bottom substrate 23 is attached to the cartridge base 31 so as to cover the window frame 331 underneath thereof, and the hologram recording material is filled in the filling space (filling zone) defined by the bottom substrate 23 and the frame 22.
The hologram recording medium according to the embodiment of the present invention is formed by filling a hologram recording material such as photopolymer between the top and bottom planar substrates. Further, the frame for ensuring a filling space for the hologram recording material is interposed between the top and bottom substrates. The frame has at least one notch portion formed in its inner peripheral part, and accordingly, the hologram recording material is filled in the notch portion and the filling space. The notch portion allows the hologram recording material to be uniformly spread over in the filling space in its entirety, and to form a recording layer having a substantially uniform thickness. That is, the notch portion serves as a place where a surplus hologram recording material which has no destination since the hologram recording material is depressed by the top substrate escapes during the manufacturing process of the hologram recording medium. Thus, the hologram recording material can have a uniform thickness in a part which constitutes of an information recording zone (the filling space). With the provision of the notch portion (the material trapping part or the material relief part), a hologram recording medium which can eliminate a problem of inferior filling of the material can be materialized. Further, with the notch portion, the regulation for the thickness can be facilitated, and accordingly, a hologram recording medium having no unevenness in thickness, that is, having a precise thickness can be materialized.
It is noted that the bottom substrate may be integrally incorporated with the frame or may be bonded thereto by means of an adhesive. In particular, the integral incorporation thereof can completely prevent occurrence of such a risk that the hologram recording material leaks through a gap between the bottom substrate and the frame.
In order to allow the top substrate to depress the hologram recording material, it is desirable that the top substrate has a size which is smaller than the size of the inner peripheral part of the frame since the thickness of the hologram recording material is defined by the depressing pressure of the top substrate during the manufacturing step. Thus, it is possible to form a recording layer having a predetermined thickness.
Further, the top and bottom substrate and the frame are rectangular and accordingly, the recording medium has rectangular shape in its entirety. Thus, the recording medium accommodated even in a cartridge may have an increased recording capacity in comparison with a disc shape recording medium. In the case of the configuration of a rectangular hologram recording medium, a notch portion may be formed in at least one corner of the frame, but it is more preferably to form the notch portion in each of the four corners of the frame.
In the embodiments of the present invention, there is provided a hologram cartridge media accommodating therein the above-mentioned hologram recording medium. In this case, the hologram cartridge media comprises a hologram recording medium having any one of the configurations as stated above, a cartridge base accommodating the hologram recording medium therein and having a window frame through which at least a part of the hologram recording medium is exposed so as to serve as a recording surface, and a cartridge cover for enclosing the hologram recording medium in cooperation with the cartridge base. The hologram cartridge media can prevent the hologram recording medium enclosed therein from being optically sensitized. Thus, there may be provided a recording medium which is convenient in use for the user. Further, with the incorporation of the moisture-proof sealing film interposed between the hologram recoding medium and the cartridge, the environmental resistance thereof can be enhanced. It is noted that moisture-proof sealing film may be applied thereover with a reflective coating in the case of the provision of a hologram recording medium exclusively used as a ROM. This reflective film can reflect a reference beam during the information reproduction.
Further, with the provision of the cartridge base formed therein with a notch for positioning the cartridge media in a drive unit during loading thereof, the positioning of the cartridge media can be precisely carried out during recording and reproduction even with a simple configuration.
Further, with the provision of the cartridge cover marked with an arrow for indication of a direction of loading the cartridge media, there can be prevent such a risk that the user loads the cartridge media in an erroneous direction.
Patent Application
20080063947
