Abstract:
According to the present invention, there is provided a disk cartridge capable of being made compact although the disc cartridge has double structure, which cartridge is improved in light blocking effect and dustproof property, and is particularly suitable for use as a media disk. In this disk cartridge, a shutter is slidably mounted between an inner case and an outer case, and a joint surfaces of upper and lower halves of the inner case, and joint surfaces of upper and lower halves of the outer case are provided at positions at different heights. Light incidence preventing parts which consist of sets of a plurality of lines of ribbed projections are formed on an inner surface of the upper half and an inner surface of the lower half of the outer case.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a disk cartridge for accommodating a disk-shaped recording medium, and more particularly, to a disk cartridge having double structure suitable for accommodating a hologram media disk. 
   2. Description of the Prior Art 
   In recent years, a hologram media disk comes to the fore, which disk has considerably large information storage capacity as compared with a conventional disk-shaped recording medium such as a CD (compact disk) or a DVD (digital video disk). The hologram media disk also has an advantage of being capable of simplifying a drive system of a recording and reproducing apparatus since it has no need to rotationally drive the disk at a high speed. 
   In digital hologram recording by using this hologram media disk, information is recorded at an interference point in a thickness direction of a recording layer utilizing interference of a recording beam and a reference beam, and the information recorded at this interference point is read out by the reference beam, unlike the digital recording using the conventional disk-shaped recording media. This method makes it possible to record and reproduce a large amount of information at a high speed, since the method can record and reproduce a large amount of data by one light irradiation. 
   The recording media used for the digital hologram recording is constructed by sandwiching a hologram material between two disk substrates. Conventionally, this hologram material is composed mainly of inorganic single crystal called as photorefractive crystal such as lithium niobate single crystal, and therefore, has problems of being expensive and difficult to process. However, an organic hologram material including a photo polymerization material as a base, which has been investigated in recent years, can be expected to make dramatic improvement concerning the above described problems. More specifically, as an organic hologram recording material, a material which is made by mixing and diffusing the photo polymerization material serving as a recording material into a polymer matrix serving as a support medium is used, and when producing the recording media, this material is diluted by a solvent and coated on a substrate as a coating material, or this material is worked into a film form and then attached on a base material. 
   However, the hologram material using a photosensitive copolymer is easily deteriorated by exposure to external light, and therefore, in order to putting a recordable or rewritable hologram media disk into practical use, it is necessary to block the external light by accommodating the hologram media disk in a disk cartridge with light blocking effect. 
   Conventionally, in order to protect the disk-shaped recording media from contamination and mechanical breakage in a VD (video disk) and a MD (minidisk), for example, an art of accommodating the disk-shaped recording media into the disk cartridge has been known. For example, in the specification of U.S. Pat. No. 5,526,337, there is proposed a method for securing light blocking effect during storage, by accommodating hologram media in the cartridge having light blocking effect, and by opening and closing a drive shaft insertion aperture and a head access aperture by using a shutter when attaching and detaching the hologram media to and from a recording and reproducing apparatus. 
   Also, JP-A-8-55456, for example, discloses a method for making the cartridge structure double to enhance dustproof property. Alternatively, it is proposed to provide the hologram media by using a cartridge in the same shape as a 5.25 type MO cartridge of ISO. 
   The applicant of the present invention also has proposed a disk cartridge having double structure, for accommodating disk-shaped recording media, which includes: an inner case having an inner head insertion aperture and an inner spindle insertion aperture; an outer case located outside in a thickness direction of the inner case and having an outer head insertion aperture provided at a position overlaying the inner head insertion aperture and an outer spindle insertion aperture provided at a position overlaying the inner spindle insertion aperture; and a shutter slidably disposed between the inner case and the outer case to open and close these insertion apertures. The disk cartridge has been patented (Japanese Patent No. 3430184). 
   BRIEF SUMMARY OF THE INVENTION 
   However, in the case of the method described in U.S. Pat. No. 5,526,337, it is necessary to provide a clearance between the shutter and the cases for sliding the shutter, and there is the possibility that the light is directly incident on the accommodated media through this clearance. Therefore, sufficient light blocking effect and dustproof property have not been obtained. 
   Although the method of interposing the shutter between the inner case and the outer case by using the cartridge of double structure as disclosed in JP-A-8-55456 surely solves the problems of light blocking effect and dustproof property concerning the portions of the head access aperture and the drive shaft insertion aperture, it does not assume the use in the hologram media. Therefore, the other portions have the problem about the light blocking effect, and thus the method is unsuitable for the cartridge for the hologram media. Further, due to the double structure, the cartridge itself is entirely large as compared with the size of the disk to be accommodated therein. 
   In the disk cartridge of the double structure described in the specification of Japanese Patent No. 3430184 by the applicant of the present invention, the incident route of the external light to the disk-shaped recording media accommodated in the disk cartridge is long and complicated as compared with the case using the above described disk cartridge of the single structure, and therefore, the disk-shaped recording media is hardly exposed to the external light, and the disk cartridge of the double structure is suitable as a disk cartridge for the hologram media disk. 
   However, in the case of the disk cartridge of the double structure, there is no means for preventing incidence of the external light between the shutter and the shutter sliding surface of the case, and therefore, the external light cannot be completely prevented from leaking into the inner case. Therefore, it cannot be said that this disk cartridge is sufficient as a disk cartridge for the hologram media disk. 
   The present invention is made to solve the problems of the above prior arts, and its object is to provide a disk cartridge capable of being made compact regardless of the double structure. Another object of the present invention is to provide a disk cartridge capable of preventing light exposure of the disk-shaped recording media when closing a shutter, particularly, a disk cartridge having light blocking effect and dustproof property preferable for an information recording medium such as a hologram medium which is easily deteriorated by the light. 
   Therefore, according to a first aspect of the present invention, there is provided a disk cartridge provided including a slidable shutter between an inner case and an outer case, which disk cartridge has double structure in which joint surfaces of an upper half and a lower half of the outer case, and joint surfaces of an upper half and a lower half of the inner case are positioned at different heights. Since the heights of the joint surfaces of the upper half and the lower half of the outer case and the joint surfaces of the upper half and the lower half of the inner case are shifted, a gap space in the cross-section of the cases becomes step-like, and therefore, the structure in which light and dust hardly enter is provided. As a result, light blocking effect and dustproof property are enhanced. 
   According to a second aspect of the present invention, there is provided a disk cartridge having double structure, which includes a slider for slidably mounting a shutter between an inner case and an outer case, wherein the slider has a pin for positioning the shutter, and the shutter has a hole in which the pin of the slider is inserted, whereby the slider and the shutter are connected by fitting this pin into the hole. An edge portion of the shutter is disposed between the inner case and the outer case, so that the structure enhanced in light blocking effect and dustproof property can be provided. Also, since the shutter is positioned by the pin, it becomes unnecessary to fix the shutter by means of a screw or the like. Further, the slide of the shutter is restrained by the outer case and the inner case, and therefore, the number of components can be reduced. According to this structure, it becomes possible to assemble the disk cartridge easily. 
   According to a third aspect of the present invention, there is provided a disk cartridge having double structure in which a shutter includes a head insertion aperture opening and closing part, a spindle insertion aperture opening and closing part, and a fix connection part for connecting the head insertion aperture opening and closing part and the spindle insertion aperture opening and closing part, and this fix connection part is disposed between an inner case and an outer case so as not to be exposed to the outside of the cases. Since the shutter fix connection part is not exposed to the outside, it can be prevented that the shutter is removed unexpectedly, deformed, or the shutter is deliberately opened and closed, and therefore, there is no fear that light is applied to an unrecorded hologram medium by mistake. 
   According to a fourth aspect of the present invention, there is provided a cartridge having double structure, which includes a lock member for locking and releasing a shutter, wherein a pivot portion center of this lock member is provided on an inner case side, and a restraining portion of the lock member is provided in an outer case side. This construction makes it unnecessary to consider that the shutter is interfered by the difference in engaging level of the inner case and the outer case when the shutter slides, and therefore, free design is made possible concerning the shape of the slider. 
   According to a fifth aspect of the present invention, there is provided a disk cartridge having double structure in which a pin for positioning an inner case is provided in an outer case, and an insertion aperture of the positioning pin is provided in the inner case. By providing the positioning pin and the aperture in the inner case and the outer case respectively, positioning of the inner case and the outer case is not only facilitated, but also the number of components can be reduced by substituting the pin and aperture for a member for fixing an upper half and a lower half of the inner case, and therefore, it becomes possible to facilitate assembly. 
   According to a sixth aspect of the present invention, there is provided a disk cartridge which is constructed so that the maximum lateral width portions of disk housing parts of an inner case and an outer case become thin-walled portions. The thin-walled portion is provided so that the maximum lateral width portion of the inner case is substantially the same as an outer shape of a disk to be accommodated, and a portion of the outer case corresponding to this portion is a thin-walled portion, whereby it is not necessary to make the outer shape large regardless of the double structure, and therefore, a disk cartridge having double structure of the same size as 5.25 type optical magnetic disk of the ISO standard, for example, can be provided. 
   A seventh aspect of the present invention is directed to a disk cartridge in which a shutter is provided in the vicinity of a center in a cartridge width direction and the shutter can be opened and closed only in one of left and right directions. Two pairs of shutter opening and closing arms and error insertion preventing arm are provided on a drive (driving system), and a recessed shape for releasing the arms and a recessed shape which works as a reverse insertion preventing stopper are provided in a combination state, in the disk cartridge. According to this construction, even if a disk cartridge of a single-sided specification for accommodating a single-sided recording disk and a disk cartridge of a both-side specification for accommodating a both side recording disk exist in a mixed state, the disk cartridge of the single-sided specification can be inserted only in a normal direction, and the disk cartridge of the both-side specification can be inserted in both normal and reverse directions. According to the seventh aspect of the present invention, the disk cartridge having such a shutter opening and closing structure and the apparatus for recording and reproducing it are provided. 
   According to the first to seventh aspects of the present invention, a disk cartridge of the same size as a normal cartridge, excellent in light blocking effect and dustproof property with a small number of components can be provided while the disk cartridge has dual structure. The disk cartridge according to the present invention is especially preferable for the information recording media such as a hologram medium which need highly light blocking effect. 
   According to an eighth aspect of the present invention, there is provided a disk cartridge having double structure, which includes: an inner case having an inner head insertion aperture and an inner spindle insertion aperture for accommodating a disk-shaped recording medium therein; an outer case located outside in a thickness direction of the inner case, the outer case having an outer head insertion aperture provided in a position overlapping with the inner head insertion aperture, and an outer spindle insertion aperture provided in a position overlapping with the inner spindle insertion aperture; and a shutter slidably disposed between the inner case and the outer case for opening and closing the inner head insertion aperture and the outer head insertion aperture, and the inner spindle insertion aperture and the outer spindle insertion aperture. This disk cartridge includes light incidence preventing parts for preventing external light from leaking into the inner case from a gap between the shutter and the shutter sliding surface, which light incidence preventing parts are provided on the shutter sliding surface on the outer side of the inner case and the shutter sliding surface of inner side of the outer case. 
   The external light passing between the shutter and the shutter sliding surface so as to come into the inner case can be blocked by providing the light incidence preventing parts for preventing the leakage of the external light into the inner case on the shutter sliding surface of the inner case and/or the shutter sliding surface of the outer case constructing the disk cartridge having the double structure, and therefore, deterioration of the hologram media disk due to exposure to the external light can be prevented. 
   According to the present invention, the light incidence preventing part may be provided only in a peripheral portion of each insertion port on the shutter sliding surfaces in the disk cartridge of the above described construction. 
   The leakage of the external light into the inner case when the shutter is closed occurs in a portion where the shutter and the shutter sliding surface overlap with each other, namely, in a gap between the outer edge portion of the shutter and the peripheral portion of each of the insertion port. Accordingly, the exposure preventing effect for the disk-shaped recording media, which is practically sufficient, can be obtained by providing the light incidence preventing part only in the peripheral portion of the necessary insertion port. 
   According to the present invention, in the disk cartridge of the above described construction, a rib-shaped or crimp-shaped (or wave-shaped) projection may be formed on the shutter sliding surface as a light incidence preventing part. 
   By forming the rib-shaped or crimp-shaped projection on the shutter sliding surface, the external light incident from a gap between the shutter and the shutter sliding surface can be reflected and/or diffracted by a wall surface of the projection, and therefore, the external light toward the inside of the inner case can be blocked, and leakage of the external light into the inner case can be prevented. Further, since a contact area of the shutter and the shutter sliding surface is small, the operation of the shutter can be light. 
   Further, according to the present invention, in the disk cartridge of the above described construction, a combination of the rib-shaped and crimp-shaped projections may be formed on the shutter sliding surface as a light incidence preventing part. 
   By combining the rib-shaped projection and the crimp-shaped projection like this, the rib-shaped projections and the crimp-shaped projections can be properly arranged in accordance with a state of the shutter sliding surface, so that easiness of forming the inner case and/or the outer case, and slidability of the shutter are improved. 
   Further, according to the present invention, in the disk cartridge of the above described construction, a hair implant may be applied onto the shutter sliding surface as a light incidence preventing part. 
   According to such construction, the external light incident from a gap between the shutter and the shutter sliding surface can be reflected and/or diffracted by the hair implant, and therefore, the same operational effects as in the case when the rib-shaped or crimp-shaped recessions and projections are formed on the shutter sliding surface can be obtained. 
   Further, according to the present invention, in the disk cartridge of the above described construction, a combination of the rib-shaped or crimp-shaped projection and the hair implant may be formed on the shutter sliding surface as a light incidence preventing part. 
   According to the above construction, the rib-shaped projection or the crimp-shaped projection and the implanted hair can be suitably arranged in accordance with a state of the shutter sliding surface, and therefore, the forming easiness of the inner case and/or the outer case, and the slidability of the shutter can be improved. 
   Further, according to the present invention, in the disk cartridge of the above described construction, an antireflection sheet may be stuck on the shutter sliding surface as a light incidence preventing part. 
   By sticking the antireflection sheet on the shutter sliding surface, multiple reflections of the external light incident from a gap between the shutter and the shutter sliding surface can be prevented, so that leakage of the external light into the inner case is prevented. Further, since a member excellent in lubricity is disposed between the shutter and the shutter sliding surface, the operation of the shutter becomes light. 
   Further, according to the present invention, in the disk cartridge of the above described construction, painting of dark color such as black may be applied to the shutter sliding surface as a light incidence preventing part. 
   The external light incident from a gap between the shutter and the shutter sliding surface is absorbed by the painted surface of dark color by applying the painting of dark color onto the shutter sliding surface, and its multiple reflections are prevented. Therefore, the external light toward the inside of the inner case can be blocked, namely, the external light toward the inside of the inner case can be prevented. 
   Further, according to the present invention, in the disk cartridge of the above described construction, painting of dark color such as black may be applied onto a surface of the shutter opposed to the inner case and/or a surface of the shutter oppose to the outer case as a light incidence preventing part. 
   According to such construction, the external light incident from a gap between the shutter and the shutter sliding surface is absorbed by the painted surface of dark color, and its multiple reflections are prevented, and therefore, the external light toward the inside of the inner case can be blocked, namely, leakage of the external light into the inner case can be prevented. 
   Since the disk cartridge according to the eighth aspect of the present invention includes the light incidence preventing part on the shutter sliding surface of the inner case and/or the outer case, the external light which passes between the shutter and the shutter sliding surface to come into the inner case can be blocked, and deterioration of the hologram media disk due to exposure to the external light can be prevented. 
   Embodiments of the present invention will be explained below based on the drawings. 
   The other objects, characteristics and advantages of the present invention will become apparent from the description of the embodiments of the present invention relating to the attached drawings. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       FIG. 1  is an exploded perspective view of a disk cartridge according to an embodiment of the present invention; 
       FIG. 2  is a front view and a partially enlarged sectional view showing the difference in jointed level of an inner case and an outer case according to the embodiment of the present invention; 
       FIG. 3  is a view showing thin-walled portions of an inner case and an outer case along a disk outer peripheral shape, according to the embodiment of the present invention; 
       FIG. 4  is a view showing a fully opened state of a shutter of the disk cartridge according to the embodiment of the present invention; 
       FIG. 5  is a view showing a closed state of the shutter of the disk cartridge according to the embodiment of the present invention; 
       FIG. 6  is a view showing a half-opened state of the shutter of the disc cartridge according to the embodiment of the present invention; 
       FIG. 7  is an enlarged view of a lock mechanism part of the disk cartridge according to the embodiment of the present invention; 
       FIG. 8  is an enlarged view of the lock mechanism part of the disk cartridge according to the embodiment of the present invention; 
       FIG. 9  is a view seen from the slider side, which shows a shutter closed state at the time of insertion of the disk cartridge having an incorrect insertion preventing function according to the embodiment of the present invention; 
       FIG. 10  is a view seen from the slider side, which shows a shutter opened state at the time of insertion of the disk cartridge having the incorrect insertion preventing function according to the embodiment of the present invention; 
       FIG. 11  is a view seen from the slider side, which shows a state when the disk cartridge having the incorrect insertion preventing function according to the embodiment of the present invention is inserted downside up; 
       FIG. 12  is a view of an outer surface of an upper half of the inner case according to the embodiment of the present invention; 
       FIG. 13  is a view of an outer surface of a lower half of the inner case according to the embodiment of the present invention; 
       FIG. 14  is a view of an inner surface of an upper half of the outer case according to the embodiment of the present invention; 
       FIG. 15  is an enlarged plane view of the portion B in  FIG. 14 ; 
       FIG. 16  is an enlarged sectional view taken along the line C-C in  FIG. 14 ; 
       FIG. 17  is a view of the inner surface of a lower half of the outer case according to the embodiment of the present invention; 
       FIG. 18  is an enlarged sectional view of a substantial part of the disk cartridge according to the embodiment of the present invention; 
       FIG. 19  is an enlarged plane view of a substantial part of a disk cartridge according to another embodiment of the present invention; 
       FIG. 20  is an enlarged sectional view of a substantial part of a disk cartridge according to still another embodiment of the present invention; 
       FIG. 21  is an enlarged sectional view of a substantial part of a disk cartridge according to still another embodiment of the present invention; 
       FIG. 22  is an enlarged sectional view of a substantial part of a disk cartridge according to still another embodiment of the present invention; 
       FIG. 23  is an enlarged sectional view of a substantial part of a disk cartridge according to still another embodiment of the present invention; 
       FIG. 24  is an enlarged sectional view of a substantial part of a disk cartridge according to still another embodiment of the present invention; 
       FIG. 25  is an enlarged sectional view of a substantial part of a disk cartridge according to still another embodiment of the present invention; 
       FIG. 26  is an enlarged sectional view of a substantial part of a disk cartridge according to still another embodiment of the present invention; 
       FIG. 27  is an enlarged sectional view of a substantial part of a disk cartridge according to still another embodiment of the present invention; 
       FIG. 28  is an enlarged sectional view of a substantial part of a disk cartridge according to still another embodiment of the present invention; 
       FIG. 29  is an enlarged sectional view of a substantial part of a disk cartridge according to still another embodiment of the present invention; 
       FIG. 30  is an enlarged sectional view of a substantial part of a disk cartridge according to still another embodiment of the present invention; 
       FIG. 31  is an enlarged sectional view of a substantial part of a disk cartridge according to still another embodiment of the present invention; 
       FIG. 32  is an enlarged sectional view of a substantial part of a disk cartridge according to still another embodiment of the present invention; 
       FIG. 33  is an enlarged sectional view of a substantial part of a disk cartridge according to still another embodiment of the present invention; 
       FIG. 34  is an enlarged sectional view of a substantial part of a disk cartridge according to still another embodiment of the present invention; 
       FIG. 35  is an enlarged sectional view of a substantial part of a disk cartridge according to still another embodiment of the present invention; 
       FIG. 36  is a front view of the disk cartridge according to the embodiment of the present invention; and 
       FIG. 37  is an enlarged sectional view taken along the line D-D in  FIG. 36 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   (1. Construction of A Double Structure Cartridge) 
   As shown in  FIG. 1 , a disk cartridge according to an embodiment of the present invention is constructed mainly by a disk-shaped recording medium  1 , an inner case  2 , an outer case  3 , a slider  4 , a shutter  5  and a lock member  60 . 
   Any known disk-shaped recording medium can be accommodated as the disk-shaped recording medium  1 , however, in this embodiment, a hologram media disk constructed by sandwiching hologram between two disk substrates is accommodated. The construction of the hologram media disk is known, and is not the gist of the present invention, and therefore, the explanation will be omitted. 
   The inner case  2  consists of an upper half  22  and a lower half  24 , and provides double case structure with the outer case  3  consisting of an upper half  32  and a lower half  34  disposed outside the inner case  2  in the thickness direction. 
   As shown in  FIG. 1 , an outer head insertion aperture  31  is formed substantially in a center of the upper half  32  on a side of the shutter  5 , and an outer spindle insertion aperture (or an outer lower head insertion aperture)  33  is formed substantially in a center of the lower half  34  on the side of the shutter  5 . 
   A shutter sliding surface  38  having a size including the outer spindle insertion aperture  33  is formed so as to be lowered by one step on an inner surface of the lower half  34 , and a shutter sliding surface  36  (not shown) is formed similarly on an inner surface of the upper half  32 . Shutter sliding surfaces  26  and  27  are also formed on the upper and lower halves  22  and  24  so as to substantially correspond to the outlines of the shutter sliding surfaces  36  and  38 . By the shutter sliding surfaces  36  and  38  and the shutter sliding surfaces  26  and  27 , clearances for sliding the head insertion aperture opening and closing part  52  and the spindle insertion aperture opening and closing part  53  of the shutter  5  are formed between the upper half  22  and the upper half  32 , and between the lower half  24  and the lower half  34 , respectively, so that a sliding area of the shutter  5  is restrained. 
   The upper half  32  and the lower half  34  are formed to have the same thickness, but the upper half  22  and the lower half  24  are formed to have a different thickness ratio. As a result, the difference in level is provided between a joint position of the inner cases and a joint position of the outer cases as shown in  FIG. 2 , and thereby, light block effect and dustproof property are enhanced. 
   As shown in  FIG. 3 , a curved surface part  18  along an outer peripheral shape of the disk recording medium  1  is provided in a part of the lower half  24  of the inner case  2 , and a thin-walled part  19  is provided in a spot corresponding to the curved surface part  18 , of the lower half  34  of the outer case  3 . This construction makes it possible to accommodate the disk recording medium having a larger diameter than that of the conventional disk cartridge having the same width dimension. 
   As shown in  FIGS. 36 and 37 , projected portions E and F for fastening the upper half  32  and the lower half  34  are provided on the inside of the outer case  3 , and recessed portions G and H are provided in positions of the upper half  22  and the lower half  24  of the inner case  2 , corresponding to the projected portions E and F, whereby it becomes unnecessary to fasten the upper half  22  and the lower half  24  of the inner case  2 , and reduction in the number of components becomes possible. In addition, positioning of the outer cartridge  2  can be easily made. 
   (2. Mounting of A Slider And A Shutter) 
   As shown in  FIG. 1 , the shutter  5  is constructed by the head insertion aperture opening and closing part  52 , the spindle insertion aperture opening and closing part  53 , and the fixing part  51 . The shutter  5  is combined with the slider  4 , and slides along a slider rail  22   a  provided in the upper half  22  and a slider rail  24   a  provided in the lower half  24 . 
   The shutter  5  is mounted so as to be restrained in position in the lateral direction of a front view shown in  FIG. 2  by a positioning projected part  4   a  provided in the slider  4  and a hole part  5   a  into which the projected part  4   a  is fitted, and which hole part  5   a  is provided in the fixing part  51  of the shutter  5 . The shutter  5  is restrained in its displacement in an upward direction in the front view shown in  FIG. 2  by the outer case  3 . 
   The fixing part  51  of the shutter  5  is covered with bridges  32   a  and  34   a  which form end portions of the outer head insertion aperture  31  of the upper half  32  and the outer spindle insertion aperture  33  of the lower half  34 , and therefore, the fixing part  51  hardly has an exposed portion. Further, when the shutter  5  is in an opened state ( FIG. 4 ), the fixing part  51  slides between the inner case  2  and the outer case  3 , so that the entire shutter  5  is not exposed to a surface. Such a structure is advantageous for preventing the shutter from opening unexpectedly. 
   (3. Lock Mechanism) 
   As shown in  FIGS. 7 and 8 , the lock member  60  which is designed to be engaged with the slider  4  to lock (or lock and release) the shutter  5  in a position of a closed state ( FIG. 5 ) is provided. A pivot portion center  60   a  of the lock member  60  is provided in the inner case  2 , and a restraining portion  60   b  of the lock member  60  is provided in the outer case  3 , whereby a fitting gap of the inner case  2  and the outer case  3  can be prevented from existing on a surface on which the slider  4  slides to open and close the shutter  5 . When the lock is released and the shutter  5  slides, it is not necessary to consider interference with the slider  4  by the fitting gap of the inner case  2  and the outer case  3 , and therefore, it is possible to freely design the shape of the slider  4 . 
   (4. Error Insertion Preventing Mechanism) 
   A disk drive (not shown) for recording and reproducing the disk cartridge according to the embodiment of the present invention is provided with two shutter opening and closing arms  13 , and an error insertion (incorrect insertion) preventing arm  14  ( FIGS. 9 to 11 ). In order to open and close the shutter  5 , one of the shutter opening and closing arms  13  is disposed at a location where it abuts on the slider  4  incorporated in the disk cartridge, and an arm release recessed shape  15  in which the other shutter opening and closing arm  13  (which has not performed a shutter opening operation when the shutter  5  is fully opened), and the error insertion preventing arm  14  enter is provided in the disk cartridge. The disk cartridge is provided with a reverse direction insertion preventing stopper  16  in a recessed shape in which the error insertion preventing arm  14  is caught when the disk cartridge of the single-sided specification is inserted downside up. 
   Here, the shutter opening and closing arm  13  located on the lower right side of the disk cartridge in  FIG. 9  is set as an opening and closing arm  13   a,  and the shutter opening and closing arm  13  located at the upper left side is set as an opening and closing arm  13   b,  for convenience. 
     FIG. 9  shows a shutter closed state of the disk cartridge of the single-sided specification. When the disk cartridge of the single-sided specification is correctly inserted, the opening and closing arm  13   a  operates to open the shutter  5  as shown in  FIG. 10 , and meanwhile, the opening and closing arm  13   b  and the reverse insertion preventing arm  14  slide on the surface of the disk cartridge on the side of the shutter  5 , and get into the arm release recessed shape  15  when the shutter  5  comes to the vicinity of the fully opened position. When the disk cartridge is inserted downside up, the error insertion preventing arm  14  is caught by the error insertion preventing stopper  16  as shown in  FIG. 11 , and the slider  4  cannot be opened. 
   In the case of the disk cartridge of a double-sided specification, when it is inserted in one direction, the opening and closing arm  13   a  operates to open the shutter  5  as in the case where the disk cartridge of a single-sided specification is inserted, and at the same time, the opening and closing arm  13   b  and the error insertion preventing arm  14  slide on the surface of the disk cartridge on the slider side, and get into the arm release recessed shape  15  when the shutter  5  is substantially fully opened, whereby the shutter  5  is fully opened. When the disk cartridge is inserted in the opposite direction, the opening and closing arm  13   b  operates to open the shutter  5 , and at the same time, the opening and closing arm  13   a  and the error insertion preventing arm  14  slide on the surface of the disk cartridge on the side of the slider, and get into the arm release recessed shape  15  when the shutter  5  is substantially fully opened, whereby the shutter  5  is fully opened. 
   (5. Light Incidence Prevention Mechanism) 
   As shown in  FIG. 1 , the inner head insertion aperture  21  is formed in the upper half  22  of the inner case  2  and the inner spindle insertion aperture  23  is formed in the lower half  24 . A slider setting part  25  for slidably mounting the slider  4  is provided on a side at one end of the inner case  2 . As shown in detail in  FIG. 12 , the shutter sliding surface  26  of a shallow recessed shape is formed over an area where the shutter  5  is movable including an area of the inner head insertion aperture  21 , on an outer surface of the upper half  22 . The shutter sliding surface  27  of a shallow recessed shape is also formed over an area, where the shutter  5  is movable, including the area of the inner spindle insertion aperture  23 , on an outer surface of the lower half  24  ( FIG. 13 ). 
   The outer head insertion aperture  31  is formed in the upper half  32  of the outer case  3 , and the outer spindle insertion aperture  33  is formed in the lower half  34 . A slider operation part  35  for receiving a shutter operating member of the recording and reproducing apparatus to operate the slider  4  to open and close it is provided on a side at one end of the outer case  3 . As shown in detail in  FIG. 14 , the shutter sliding surface  36  of a shallow recessed shape is formed over the area, where the shutter  5  is movable, including the area of the outer head insertion aperture  31 , on the inner surface of the upper half  32 . As shown in  FIGS. 14 to 16 , a light incidence preventing part  37  consisting of a set of plurality of lines (or streaks) (five lines in the example in  FIGS. 15 and 16 , and thee lines in the example in  FIG. 18 ) of rib-shaped projections is formed on the peripheral portion of the outer head insertion aperture  31  on the shutter sliding surface  36  to be parallel to the periphery of the outer head insertion aperture  31 . As shown in detail in  FIG. 17 , the shutter sliding surface  38  of the shallow recessed shape is formed over the area, where the shutter  5  is movable, including the area of the outer spindle insertion aperture  33 , on the inner surface of the lower half  34 , and a light incidence preventing part  39  similar to the light incidence preventing part  37  formed on the inner surface of the upper half  32  is formed on the peripheral portion of the outer spindle insertion aperture  33  in the shutter sliding surface  38 . 
   The insertion apertures  21 ,  23 ,  31  and  33  are formed in positions where those overlap with each other when the halves  22 ,  24 ,  32  and  34  are assembled as shown in  FIG. 1 . 
   The slider  4  is provided so as to smoothly open and close the shutter  5 , and can be formed from a material such as polyacetal resin excellent in lubriciy, for example. 
   The shutter  5  is formed by the fixing part  51 , the head insertion aperture opening and closing part  52  and the spindle insertion aperture opening and closing part  53  so that its side shape has a U-shape, and is disposed between the shutter sliding surfaces  26  and  27  of the inner case  2 , and the shutter sliding surfaces  36  and  38  of the outer case  3  as shown in  FIG. 18 . 
   In the disk cartridge of this embodiment, the light incidence preventing parts  37  and  39  each consisting of a set of rib-shaped projections are provided on the shutter sliding surfaces  36  and  38  of the outer case  3  as shown in  FIG. 18 , and therefore, the external light L incident between the shutter  5  and the shutter sliding surfaces  36  and  38  is reflected by wall surfaces of the light incidence preventing parts  37  and  39 , and the external light L which comes into the inner case  2  from between the shutter  5  and the shutter sliding surfaces  36  and  38  is blocked, whereby deterioration of the hologram media disk  1  by exposure to the external light can be prevented. Since the contact area of the shutter  5  and the shutter sliding surfaces  36  and  38  is small, the operation of the shutter  5  can be made light. 
   Other embodiments of the light incidence preventing mechanism according to the present invention will be cited. 
   (1) Instead of the light incidence preventing parts  37  and  39  each consisting of a set of rib-shaped projections, light incidence preventing parts  37   a  and  39   a  each consisting of a set of crimp-shaped projections can be formed as shown in  FIG. 19 . In this case, the external light L incident between the shutter  5  and the shutter sliding surfaces  36  and  38  is also reflected and diffracted by wall surfaces of the light incidence preventing parts  37   a  and  39   a,  and therefore, the external light L which passes between the shutter  5  and the shutter sliding surfaces  36  and  38  so as to come into the inner case  2  can be blocked. 
   (2) Instead of the construction consisting of a single kind of projection as described above, the light incidence preventing mechanism can be formed by combining the light incidence preventing parts  37  and  39  each consisting of a set of the rib-shaped projections and light incidence preventing parts  37   a  and  39   a  each consisting of a set of crimp-shaped projections as shown in  FIG. 20 . According to this construction, the rib-shaped projections and the crimp-shaped projections can be suitably disposed in accordance with the states of the shutter sliding surfaces  36  and  38 , and therefore, easiness of forming the inner case  2  and/or the outer case  3  and slidability of the shutter  5  can be enhanced. 
   (3) Instead of the construction consisting of a set of projections as described above, light incidence preventing parts  37   b  and  39   b  consisting of implanted hair can be formed as shown in  FIG. 21 . In this case, the external light L incident between the shutter  5  and the shutter sliding surfaces  36  and  38  is reflected and diffracted by the implanted hair  37   b  and  39   b,  and therefore, the external light L which passes between the shutter  5  and the shutter sliding surfaces  36  and  38  so as to come into the inner case  2  can be blocked. 
   (4) The light incidence preventing parts  37  and  39  each consisting of a set of rib-shaped projections and the light incidence preventing parts  37   b  and  39   b  each consisting of implanted hair can be combined as shown in  FIG. 22 , and the light incidence preventing parts  37   a  and  39   a  each consisting of a set of crimp-shaped projections and the light incidence preventing parts  37   b  and  39   b  each consisting of the implanted hair can be combined as shown in  FIG. 23 . Further, the light incidence preventing parts  37  and  39  each consisting of a set of rib-shaped projections, the light incidence preventing parts  37   a  and  39   a  each consisting of a set of crimp-shaped projections, and the light incidence preventing parts  37   b  and  39   b  each consisting of the implanted hair can be combined as shown in  FIG. 24 . According to this construction, the rib-shaped projections, the crimp-shaped projections and implanted hair can be disposed more properly in accordance with the states of the shutter sliding surfaces  36  and  38 , and therefore, the forming easiness of the inner case  2  and/or the outer case  3  and the slidability of the shutter  5  can be further enhanced. 
   (5) Instead of the construction in which the light incidence preventing parts each consisting of a set of projections or implanted hair, anti-reflection sheets  37   c  and  39   c  such as unwoven cloth or a polytetrafluoroethylene sheet can be applied to desired positions of the upper half  32  and the lower half  34  of the outer case  2  as shown in  FIG. 25 , and painting  37   d  and  39   d  of dark color such as black can be applied to desired positions of the upper half  32  and the lower half  34  of the outer case  2  as shown in  FIGS. 26 to 33 . In these cases, the external light L which incident by passing between the shutter  5  and the shutter sliding surfaces  36  and  38  is absorbed by the antireflection sheets  37   c  and  39   c  or the painting  37   d  and  39   d  of dark color, and therefore, multiple reflections of the external light L is prevented, whereby the external light L which passes between the shutter  5  and the shutter sliding surfaces  36  and  38  so as to come into the inner case  2  can be blocked. 
   (6) In each of the above described embodiments, the light incidence preventing parts are formed only on the shutter sliding surfaces  36  and  38  of the outer case  3 . However, as shown in  FIG. 34 , light incidence preventing parts  28  and  29  similar to the light incidence preventing parts  37  to  37   d  and  39  to  39   d  which are formed on the shutter sliding surfaces  36  and  38  of the outer case  3  can be formed on the shutter sliding surfaces  26  and  27  of the inner case  2 , and as shown in  FIG. 35 , light incidence preventing parts  54  and  55  similar to the light incidence preventing parts  37  to  37   d  and  39  to  39   d  which are formed on the shutter sliding surfaces  36  and  38  of the outer case  3  can be formed at the head insertion aperture opening and closing part  52  and the spindle insertion aperture opening and closing part  53  of the shutter  5 . If the light incidence preventing parts  28 ,  29 ,  37  and  39  are formed in both of the inner case  2  and the outer case  3  as shown in  FIG. 34 , incidence of the external light L into the inner case  2  can be blocked more reliably. 
   The above described description is made concerning the embodiments, but the present invention is not limited to these, and it is obvious to those skilled in the art to be able to make various changes and corrections within the spirit of the present invention and the scope of the attached claims.