Disk cartridge

A disk cartridge includes a substantially box-shaped outer case that has an opening on one end face, and an inner case that is housed in the outer case such that the inner case can be pulled out and has a concave portion for an optical disk to be placed therein. In an end portion on a side of the opening of each of an upper side plate and a lower side plate of the outer case, a substantially V-shaped cutout formed by a substantially circular arc and an inclined substantially straight line is formed. In the inner case, a substantially U-shaped cutout formed by a substantially circular arc and two inclined substantially straight lines is formed. The substantially straight line forming the substantially V-shaped cutout and the two substantially straight lines forming the substantially U-shaped cutout are virtually parallel to each other. The inner case further includes a cover that is opposed to a bottom face of the concave portion and fitted in the substantially V-shaped cutout when the inner case is housed in the outer case. Thus, a disk cartridge can be provided that allows a size reduction of a drive into which a single disk cartridge is loaded, and also can be used suitably in a changer drive.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a disk cartridge for housing an optical disk.

2. Related Background Art

Optical disks are required to be maintained always in a clean state so that recording and/or reproduction can be performed reliably. In order to prevent the adhesion of fingerprints from the touch of a finger, the occurrence of a flaw or the adhesion of dust, an optical disk is loaded into a drive for performing information recording and/or reproduction while housed in a disk cartridge. Generally, such disk cartridges are of a shutter type that includes a shutter for opening/closing windows into which an optical head, a turntable and a magnetic head are inserted. In the case where a shutter type disk cartridge is used in a changer drive, it is required that the disk cartridge housed in a stacker be conveyed from the stacker to a drive unit by a conveying means. This requires space in which the disk cartridge is moved, which has been a hindrance to higher-speed operation and size reduction.

JP 7(1995)-226045 A and the specification of U.S. Pat. No. 5,936,935 describe known examples of a conventional disk cartridge adapted to the use in compact changer drives that achieve higher-speed operation. These examples are the inventions made by the inventors of the present invention. The present invention was made to improve these examples further in terms of size reduction and optimization.

FIGS. 19Ato19E andFIGS. 20A and 20Bshow a configuration of a conventional disk cartridge that is applicable to the use in compact changer drives that achieve higher-speed operation.FIGS. 19Ato19E are external views of a disk cartridge900in a state of housing an optical disk.FIGS. 19A,19B and19C are a plan view, a side view, and a back face view, respectively.FIGS. 19D and 19Eare a side view of a rear portion and a side view of a front portion, respectively. Further,FIGS. 20A and 20Bshow a state where the optical disk is pulled out together with an inner case to such a degree that recording and/or reproduction can be performed.FIG. 20Ais a sectional plan view, andFIG. 20Bis a sectional side view. FIG.20B also shows a spindle motor, an optical head, a magnetic head and the like that are used to perform recording and/or reproduction.

As shown inFIGS. 20A and 20B, the disk cartridge900includes an outer case that is composed of a lower case half902and an upper case half903, an inner case904that is housed in a space within the outer case such that the inner case904is allowed to come in and out, and a locking member905for preventing the inner case904housed in the outer case from being pulled out unintentionally.

An optical disk901is placed in a circular concave portion904aof the inner case904. The concave portion904ais set to have an inner diameter somewhat larger than an outer diameter of the optical disk901so that the optical disk901can be rotated in the concave portion904a. Projections904iprojecting in a central direction are formed in an upper portion of a peripheral wall of the concave portion904a. The projections904ifunction to prevent the optical disk901from coming out of the concave portion904a.

A pair of the locking members905are disposed on both sides of a front end of the inner case904in a pull-out direction. When the inner case904is housed in the outer case, a convex portion905aof each of the locking members905is fitted in a concave portion (not shown) that is formed on an inner side wall of the outer case, thereby allowing the inner case904to be controlled so as not to be pulled out from the outer case. When the disk cartridge900is loaded into a drive, a pair of pull-out pins920that are provided in the drive are inserted respectively into a pair of U-shaped notches904kin directions indicated by arrows920aand subsequently moved outwardly within the notches904k. As a result, each of the locking members905is rotated about a supporting shaft905b, so that the engagement between the convex portion905aand the concave portion of the outer case is released (that is, a lock is released). Then, the pull-out pins920are moved in a direction indicated by an arrow920b, and thus the inner case904is pulled out from the outer case.

After that, as shown inFIG. 20B, from one side of the optical disk, a turntable911of a spindle motor and an optical head913that are provided in the drive move respectively toward the optical disk901, and from the other side of the optical disk, a damper912and a magnetic head914move respectively toward the optical disk901, which brings about a state for recording and/or reproduction. Although the magnetic head914is necessary in the case where the optical disk901is a magneto-optical recording medium, it is not necessary in the case where the optical disk901is a phase-change type recording medium, and in the case where the drive is intended for reproduction only.

In order for the above-mentioned conventional disk cartridge900to be brought to a state of recording and/or reproduction, as shown inFIGS. 20A and 20B, it is required that the optical disk901be pulled out from the outer case by not less than half the size of the optical disk901so that space for constituent components of the drive such as the spindle motor, the optical head and the like can be secured. This requires a drive using this disk cartridge900to have an increased depth dimension L.

Furthermore, the above-mentioned conventional disk cartridge900is intended mainly for the use in changer drives. Generally, changer drives are of a stationary type, and thus in a changer drive, an increase in the depth dimension L is tolerated. However, for the use in mobile devices such as a notebook personal computer, a PDA (personal digital assistant), a camera, a movie camera and the like, a drive is required to be reduced in size, and thus an increase in the depth dimension L of the drive is not tolerated.

In providing optimization with respect to a changer drive, in the case where it is desired that a plurality of optical disks be handled always as a set, for example, a two-disk set, desirably, a plurality of disk cartridges for housing these disks are joined to each other so as not to be separated. The above-mentioned documents describe a configuration in which a plurality of disk cartridges are joined to each other using a joining member. A reduced size of a disk cartridge requires that a joining member also be reduced in size, and an excessive size reduction of the joining member leads to difficulty in performing a joining operation.

Furthermore, the disclosures of the above-mentioned documents do not include a method of positioning the inner case904, a write-protect identifying member and the like. Generally, in a shutter type disk cartridge in common use, as shown inFIG. 21, in many cases, positioning is performed by a method in which a reference pin provided on a drive side is inserted into a reference hole956provided on a flat surface of a cartridge case for housing an optical disk. However, in this method, it is required that the disk cartridge or the reference pin on the drive side be moved relative to each other in a direction perpendicular to the flat surface of the cartridge case, i.e. in a thickness direction, and thus a drive is required to have an increased height, which has been disadvantageous. Further, as shown inFIG. 21, generally, a write-protect identifying member957is disposed on the flat surface of the cartridge case. It is required that a switch for detecting the write-protect identifying member957on the drive side be moved relative to the write-protect identifying member957in the direction perpendicular to the flat surface of the cartridge case, i.e. in the thickness direction, and thus the same problem of requiring the drive to have an increased height has been presented. Further, with the improvements in a recording density technique, a smaller disk diameter is achieved, and thereby furthering the size reduction of disk cartridges. A further size-reduction of a disk cartridge also results in an excessive size reduction of a write-protect identifying member, and thus the write-protect identifying member cannot be operated easily by fingers, which also is disadvantageous.

SUMMARY OF THE INVENTION

A first object of the present invention is to provide a disk cartridge that allows a size reduction of a drive such as a notebook personal computer, a PDA or the like, into which a single disk cartridge is loaded, and also can be used suitably in a changer drive. Furthermore, a second object of the present invention is to provide a disk cartridge that allows joining of a plurality of disk cartridges to performed easily so that in a joined state, the disk cartridges can be loaded into a changer drive.

In order to achieve the above-mentioned objects, the present invention has the following configurations.

A first disk cartridge according to the present invention includes a substantially box-shaped outer case that has an opening on one end face, and an inner case that is housed in the outer case such that the inner case can be pulled out from the opening and has a concave portion for an optical disk to be placed therein. In an end portion on a side of the opening of each of an upper side plate and a lower side plate of the outer case, the outer case has a substantially V-shaped cutout formed by a substantially circular arc and a substantially straight line that is connected to the substantially circular arc and inclined with respect to sides of the outer case. The inner case has a substantially U-shaped cutout formed by a substantially circular arc in a central portion and two substantially straight lines virtually parallel to each other that are connected to the substantially circular arc and inclined with respect to sides of the inner case. The substantially straight line forming the substantially V-shaped cutout of the outer case and the two substantially straight lines forming the substantially U-shaped cutout of the inner case are virtually parallel to each other. The inner case further includes a cover that is opposed to a bottom face of the concave portion and fitted in the substantially V-shaped cutout formed on the upper side plate of the outer case when the inner case is housed in the outer case.

A second disk cartridge according to the present invention includes a substantially box-shaped outer case that has an opening on one end face, and an inner case that is housed in the outer case such that the inner case can be pulled out from the opening and has a concave portion for an optical disk to be placed therein. In an end portion on a side of the opening of a lower side plate of the outer case, the outer case has a substantially V-shaped cutout formed by a substantially circular arc and a substantially straight line that is connected the substantially circular arc and inclined with respect to sides of the outer case. The inner case has a substantially U-shaped cutout formed by a substantially circular arc in a central portion and two substantially straight lines virtually parallel to each other that are connected to the substantially circular arc and inclined with respect to sides of the inner case. The substantially straight line forming the substantially V-shaped cutout of the outer case and the two substantially straight lines forming the substantially U-shaped cutout of the inner case are virtually parallel to each other. The inner case further includes a projection that is opposed to a bottom face of the concave portion and housed within the outer case when the inner case is housed in the outer case.

Furthermore, a third disk cartridge according to the present invention includes a substantially box-shaped outer case that has an opening on one end face, and an inner case that is housed in the outer case such that the inner case can be pulled out from the opening and has a concave portion for an optical disk to be placed therein. A projecting guide piece that is parallel to a pull-out direction of the inner case is provided on each side face of the outer case that is parallel to the pull-out direction of the inner case and orthogonal to a plane of the optical disk that is contained. The guide piece has two opposed faces that are substantially parallel to the plane of the optical disk. A distance between the two faces is narrower than a thickness of the outer case.

DETAILED DESCRIPTION OF THE INVENTION

A first disk cartridge according to the present invention includes a substantially box-shaped outer case that has an opening on one end face, and an inner case that is housed in the outer case such that the inner case can be pulled out from the opening and has a concave portion for an optical disk to be placed therein. In an end portion on a side of the opening of each of an upper side plate and a lower side plate of the outer case, the outer case has a substantially V-shaped cutout formed by a substantially circular arc and a substantially straight line that is connected to the substantially circular arc and inclined with respect to sides of the outer case. The inner case has a substantially U-shaped cutout formed by a substantially circular arc in a central portion and two substantially straight lines virtually parallel to each other that are connected to the substantially circular arc and inclined with respect to sides of the inner case. The substantially straight line forming the substantially V-shaped cutout of the outer case and the two substantially straight lines forming the substantially U-shaped cutout of the inner case are virtually parallel to each other. The inner case further includes a cover that is opposed to a bottom face of the concave portion and fitted in the substantially V-shaped cutout formed on the upper side plate of the outer case when the inner case is housed in the outer case.

According to this first disk cartridge, recording and/or reproduction can be performed on the optical disk contained therein while a pull-out amount of an inner case can be reduced to not more than half the diameter of the optical disk. Thus, it is possible to reduce the depth dimension of a drive of a type into which a single disk cartridge is loaded (hereinafter, referred to as a “single-disk drive”) such as a drive of a notebook personal computer, a PDA or the like.

Furthermore, when the inner case is pulled out by not less than half the diameter of the optical disk, a turntable of a spindle motor, an optical head, a magnetic head, and a damper of the drive can be disposed on a pull-out direction side of the inner case with respect to an opening of an outer case, and thus it is possible to configure a changer drive in which a number of disk cartridges are arranged, and a drive unit moves in an arranging direction of the disk cartridges along the side of the disk cartridges.

Thus, the first disk cartridge according to the present invention allows a reduction in size of a single-disk drive and can be used optimally in a changer drive.

Preferably, in the above-mentioned first disk cartridge, when the inner case is pulled out from the outer case so that the substantially straight line forming the substantially V-shaped cutout of the outer case substantially coincides with one of the two substantially straight lines forming the substantially U-shaped cutout of the inner case, the substantially V-shaped cutouts, the cover and the substantially U-shaped cutout form apertures, in each of which a portion of each surface of the optical disk that is placed in the concave portion of the inner case is exposed.

According to this preferred configuration, through the apertures, a turntable of a spindle motor, an optical head, a magnetic head, and a damper of a drive can be moved toward an optical disk.

Next, a second disk cartridge according to the present invention includes a substantially box-shaped outer case that has an opening on one end face, and an inner case that is housed in the outer case such that the inner case can be pulled out from the opening and has a concave portion for an optical disk to be placed therein. In an end portion on a side of the opening of a lower side plate of the outer case, the outer case has a substantially V-shaped cutout formed by a substantially circular arc and a substantially straight line that is connected the substantially circular arc and inclined with respect to sides of the outer case. The inner case has a substantially U-shaped cutout formed by a substantially circular arc in a central portion and two substantially straight lines virtually parallel to each other that are connected to the substantially circular arc and inclined with respect to sides of the inner case. The substantially straight line forming the substantially V-shaped cutout of the outer case and the two substantially straight lines forming the substantially U-shaped cutout of the inner case are virtually parallel to each other. The inner case further includes a projection that is opposed to a bottom face of the concave portion and housed within the outer case when the inner case is housed in the outer case.

According to this second disk cartridge, recording and/or reproduction can be preformed on the optical disk contained therein while a pull-out amount of the inner case can be reduced to not more than half the diameter of the optical disk. Thus, it is possible to reduce the depth dimension of a drive of a type into which a single disk cartridge is loaded (single-disk drive) such as a drive of a notebook personal computer, a PDA or the like.

Furthermore, when the inner case is pulled out by not less than half the diameter of the optical disk, a turntable of a spindle motor and an optical head of the drive can be disposed on a pull-out direction side of the inner case with respect to an opening of an outer case, and thus it is possible to configure a changer drive in which a number of disk cartridges are arranged, and a drive unit moves in an arranging direction of the disk cartridges along the side of the disk cartridges.

Thus, the second disk cartridge according to the present invention allows a reduction in size of a single-disk drive and can be used optimally in a changer drive.

Furthermore, by reducing the size of the projection to the maximum possible extent, the inner case can be formed more easily.

Preferably, in the above-mentioned second disk cartridge, the inner case further includes a bridging portion that connects between the two substantially straight lines forming the substantially U-shaped cutout. This allows the strength of the inner case to be increased.

Furthermore, preferably, in the above-mentioned second disk cartridge, when the inner case is pulled out from the outer case so that the substantially straight line forming the substantially V-shaped cutout of the outer case substantially coincides with one of the two substantially straight lines forming the substantially U-shaped cutout of the inner case, the substantially V-shaped cutout and the substantially U-shaped cutout form an aperture in which a portion of a back surface of the optical disk that is placed in the concave portion of the inner case is exposed.

According to this preferred configuration, through the aperture, a turntable of a spindle motor and an optical head of a drive can be moved toward an optical disk.

Preferably, in each of the above-mentioned first and second disk cartridges, a spindle motor and an optical head may be inserted into one or more of the apertures.

Furthermore, preferably, in each of the above-mentioned first and second disk cartridges, a center of the substantially circular arc forming the substantially U-shaped cutout of the inner case substantially coincides with a rotation center of the optical disk that is placed in the concave portion of the inner case. According to this configuration, a turntable or a damper of a drive that holds and rotates an optical disk can chuck the optical disk through the substantially U-shaped cutout.

Furthermore, preferably, in each the above-mentioned first and second disk cartridges, the substantially circular arc forming the substantially V-shaped cutout of the outer case and the substantially circular arc forming the substantially U-shaped cutout of the inner case have a radius larger than a radius of a spindle motor for driving the optical disk to rotate. According to this configuration, a spindle motor of a drive can be moved toward an optical disk through a substantially V-shaped cutout and a substantially U-shaped cutout while a pull-out amount of an inner case can be reduced to not more than half the diameter of the optical disk.

Furthermore, preferably, in each of the above-mentioned first and second disk cartridges, a notch for positioning the inner case in a drive is provided on a front end face of the inner case in a pull-out direction from the outer case. According to this configuration, in a drive, simply by pulling out an inner case to a predetermined position, positioning of the inner case can be performed with accuracy. Thus, positioning does not require a drive or a disk cartridge to be moved in a normal direction with respect to a plane of an optical disk, thereby allowing the drive to be reduced in thickness (dimension in the normal direction of the optical disk).

Furthermore, preferably, in each of the above-mentioned first and second disk cartridges, a write-protect identifying member is provided on a front end face of the inner case in a pull-out direction from the outer case. According to this configuration, in a drive, simply by pulling out an inner case to a predetermined position, a write-protect state can be detected. Thus, the detection of write protection does not require a detection switch provided in a drive or a disk cartridge to be moved in a normal direction with respect to a plane of an optical disk, thereby allowing the drive to be reduced in thickness (dimension in the normal direction of the optical disk).

Furthermore, preferably, in each of the above-mentioned first and second disk cartridges, when the inner case is housed in the outer case, the write-protect identifying member is exposed in the substantially V-shaped cutout of the outer case. According to this configuration, even with a disk cartridge reduced in size, the operability of a write-protect identifying member can be maintained.

Furthermore, preferably, in each of the above-mentioned first and second disk cartridges, an area on which a label is attached is provided on a surface of the cover of the inner case, and information regarding a type of the optical disk that is contained is recorded on the label in the form of a bar code. According to this configuration, at a point in time when a disk cartridge is inserted into a holder of a drive or a stacker of a changer drive, that is, before an inner case is pulled out from an outer case, information regarding an optical disk that is contained can be detected. This allows disk controlling information to be detected at an earlier point in time, thereby achieving a quick start-up.

Furthermore, preferably, in each of the above-mentioned first and second disk cartridges, an engaging configuration for preventing the upper side plate and the lower side plate of the outer case from being separated from the inner case when the inner case is housed in the outer case is provided at a front end of the inner case in a pull-out direction from the outer case and near the opening of the outer case. According to this configuration, the entry of dust in the outer case can prevented, thereby maintaining a clean state of an optical disk.

Next, a third disk cartridge according to the present invention includes a substantially box-shaped outer case that has an opening on one end face, and an inner case that is housed in the outer case such that the inner case can be pulled out from the opening and has a concave portion for an optical disk to be placed therein. A projecting guide piece that is parallel to a pull-out direction of the inner case is provided on each side face of the outer case that is parallel to the pull-out direction of the inner case and orthogonal to a plane of the optical disk that is contained. The guide piece has two opposed faces that are substantially parallel to the plane of the optical disk. A distance between the two faces is narrower than a thickness of the outer case.

According to this third disk cartridge, a disk cartridge can be housed in a stacker of a changer drive such that a position of the disk cartridge is controlled with accuracy. Moreover, in a joined state, disk cartridges can be arranged in close contact with each other in a stacker of a changer drive. Therefore, it is made easier to handle a plurality of optical disks as a set. Further, a stacker of a changer drive can attain improved efficiency in housing disk cartridges.

A plurality of the above-mentioned third disk cartridges can be joined into one body in such a manner as to be overlapped in the same orientation using a double-faced adhesive tape, a glue or an adhesive. According to this configuration, even with disk cartridges reduced in size, a joining operation can be performed easily. Then, in a joined sate, the disk cartridges can be mounted in a stacker of a changer drive.

Hereinafter, the disk cartridge according to the present invention will be detailed by way of embodiments with reference to the appended drawings.

The following description is directed to an embodiment of the disk cartridge according to the present invention by referring toFIGS. 1to8.

FIG. 1is an exploded perspective view showing constituent components of a disk cartridge according to Embodiment 1 of the present invention. In the figure, reference numerals100,200, and300denote an outer case, an inner case, and an optical disk, respectively. Further, reference numerals400and500denote a locking member and a write-protect identifying member, respectively.

The optical disk300shownFIG. 1is composed of an optical disk main body301and an attracting plate302of a magnetic material that is provided in a center hole. The attracting plate302is attracted to a magnet provided on a turntable of a spindle motor of a drive. That is, the optical disk300is a magnetic clamp type optical disk.

However, the optical disk according to the present invention is not limited thereto and also may be an optical disk without the attracting plate302, i.e. an optical disk that is configured only of the optical disk main body301, in other words, an optical disk adapted for mechanical clamping in which clamping of an optical disk is performed using a damper provided in a drive. Either of the above-mentioned types of optical disks can be used. The optical disk300is housed in a concave portion230of the inner case200, which is recessed in the shape of a circle. In order to allow the optical disk300to be rotated in the concave portion230, the concave portion230has an inner diameter somewhat larger than an outer diameter of the optical disk300and a depth somewhat larger than a thickness of the optical disk300.

The outer case100has an opening101on one side face and thus has the shape of a hollow box. The inner case200housing the optical disk300is housed within a hollow portion of the outer case100such that the inner case200can be pulled out from the opening101in a direction indicated by an arrow200a. When the outer case100is viewed from a normal direction with respect to a surface of the optical disk300, the outer case100has a substantially square shape, and on a side on the side of the opening101of each of an upper side plate100aand a lower side plate100bof the outer case100, a substantially V-shaped cutout104is formed that is formed by a circular arc102and a straight line103connected to the circular arc102. The straight line103is inclined with respect to sides on an outer periphery of the substantially rectangular outer case100. The circular arc102has a radius larger than a radius of the spindle motor for rotating the optical disk300that is provided in the drive. In a plane parallel to a plane of the optical disk300, a position of a center of the circular arc102in a direction orthogonal to the directions indicated by the arrow200a, i.e. come-in/out directions200aof the inner case200substantially coincides with a position of a center of the optical disk300in the direction orthogonal to the come-in/out directions200awhen the inner case200mounting the optical disk300is housed in the outer case100.

When the inner case200is viewed from the normal direction with respect to the surface of the optical disk300, the inner case200has a substantially square shape, and on one of a pair of sides of the inner case200that are parallel to the come-in/out directions200a, a substantially U-shaped cutout203is formed that is formed by a circular arc201centered at a center of the circular concave portion230(namely, a rotation center of the optical disk300that is placed in the concave portion230) and two straight lines202parallel to each other that are connected to the circular arc201. The two straight lines202are inclined with respect to sides on an outer periphery of the substantially rectangular inner case200. The spindle motor of the drive is inserted into a portion of the cutout203that is defined by the circular arc201, and an optical head of the drive is inserted into a portion of the cutout203between the two straight lines202parallel to each other. Accordingly, the circular arc201has a radius larger than a radius of the spindle motor for rotating the optical disk300that is provided in the drive. When the inner case200is housed in the outer case100, the straight lines202and the straight line103forming the substantially V-shaped cutout104of the outer case100are inclined in directions substantially parallel to each other.

In an end portion of the inner case200that is exposed from the opening101of the outer case100when the inner case200is inserted into the outer case100(hereinafter, this end portion is referred to as a “front end”), a V-shaped notch204is provided at a position closer to one end portion of an end face, and a notch250, to which the write-protect identifying member500is attached, is provided at a position closer to the other end portion of the end face.

Furthermore, in a corner portion of the front end of the inner case200, an aperture portion (through hole)240is provided, in which a locking member400is attached. On a side wall of the opening portion240, an aperture246is provided, from which a locking projection403of the locking member400projects, and on a side closer to the front end, a U-shaped notch247is provided that is used to perform a lock releasing operation. Reference numeral248denotes a pair of projections between which a spring portion402of the locking member400is held so that the locking member400can be prevented from falling off from the aperture portion240of the inner case200.

On a side wall near an end portion of the inner case200on a side opposite the front end (hereinafter, this end portion is referred to as a “rear end”), an elastic claw portion209is provided that is molded integrally with the inner case200.

Reference numeral208denotes a cover that is opposed to a bottom face of the concave portion230at a predetermined distance. The cover208has a peripheral end shape that coincides with the shape of the substantially V-shaped cutout104of the outer case100. When the inner case200is housed completely in the outer case100, the cover208fits in the cutout104of the outer case and thus functions to prevent dust from entering inside the outer case100. Further, when the inner case200is pulled out from the outer case100, the cover208functions to prevent the optical disk300from falling off from the concave portion230to the exterior.

The locking member400may have a substantially V shape. The locking member400includes a rotation shaft401provided in a portion corresponding to an apex of the substantially V shape, the elastically deformable spring portion402formed on one side with respect to the rotation shaft401, the locking projection403formed in a side portion on the other side with respect to the rotation shaft401, and a releasing lever404formed on a side opposite the rotation shaft401with respect to the locking projection403, which are molded integrally into one body.

The write protect identifying member500may be a molded product that is substantially square C-shaped in cross section.

FIGS. 2A and 2Bshow a state in which the above-mentioned components are assembled.FIG. 2Ais a perspective plan view, andFIG. 2Bis a rear side view.FIG. 3is a cross sectional view taken on line III—III passing over the rotation center of the optical disk300in FIG.2A.FIG. 4is a cross sectional view taken on line IV—IV ofFIG. 2A, andFIG. 5is a cross sectional view taken on line V—V passing through the write-protect identifying member500in FIG.2A.

The optical disk300is housed within the concave portion230of the inner case200, and the inner case200is housed inside the outer case100such that the inner case200can be pulled out. The locking projection403of the locking member400that is attached in the corner portion at the front end of the inner case100projects from the aperture246(seeFIG. 1) of the inner case200and is fitted in a locking recessed portion105that is provided on an inner wall of the outer case100. This reduces the chances of the inner case200being pulled out accidentally from the outer case100.

The cover208formed in an upper portion of the inner case200is fitted in the substantially V-shaped cutout104formed by the circular arc102and the inclined straight line103.

When the inner case200is housed completely in the outer case100, as shown inFIG. 4, an inclined convex piece210provided on each surface of the inner case200at the front end is engaged with each of inclined faces106provided at an end of the opening101of the outer case100. By this engaging configuration, the upper and lower side plates of the outer case100can be prevented from separating from upper and lower surfaces of the inner case200due to warpage, and thus the dust-proof property can be improved.

As shown inFIG. 5, the write-protect identifying member500is a molded product that is substantially square C-shaped in cross section and inserted from the front into the notch250formed on a front end face of the inner case200. The write protect identifying member500can be moved in directions parallel to the front end face of the inner case200, namely, directions indicated by an arrow502. Based on a position of the write-protect identifying member500in the directions indicated by the arrow502, it can be judged whether or not a writing/erasing operation for the optical disk300that is housed is inhibited (a write-protect state). When the inner case200is housed completely in the outer case100, as shown inFIG. 2A, the write-protect identifying member500is disposed so as to be exposed in the substantially V-shaped cutout104of the outer case100. The write-protect identifying member500is substantially square C-shaped in cross section, structured to be inserted from the front end of the inner case200, and disposed so as to be exposed in the substantially V-shaped cutout104of the outer case100. This allows the write-protect identifying member500to be pinched by fingers so that easy operation of the write-protect identifying member500can be achieved.

When this disk cartridge is loaded into the drive, a pull-out pin200provided in the drive is inserted into the U-shaped notch247provided in the inner case200from outside in a direction indicated by an arrow20a. In this case, the pull-out pin20pushes the releasing lever404of the locking member400projecting in the U-shaped notch247, and thus the locking member400is rotated, thereby releasing a lock. After that, the pull-out pin20moves in a direction indicated by an arrow20b, so that the inner case200is pulled out from the outer case100.

InFIG. 2A, a chain double-dashed line indicates a position of the front end of the inner case200when the inner case200is pulled out in a single-disk drive to such a degree that recording and/or reproduction can be performed with respect to the optical disk300(a state shown inFIG. 11B, which will be described later). In this case, the V-shaped notch204formed at the front end of the inner case200is brought into contact with a side face of a cylindrical reference pin21provided in the drive. This state is shown inFIGS. 6A and 6B.FIG. 6Ais an expanded plan view of a section VI shown inFIG. 2A, andFIG. 6Bis a cross sectional view taken on line VIB—VIB of FIG.6A. The reference pin21may be composed of a cylinder portion21ahaving a height that is substantially the same as a thickness of a front end portion of the inner case200and height controlling flange portions21bthat are provided respectively at upper and lower ends of the cylinder portion21aand have a diameter larger than an outer diameter of the cylinder portion21a. The cylinder portion21acontrols a position of the inner case200in the plane parallel to the plane of the optical disk300. The pair of the height controlling flange portions21bcontrol a position of the inner case200in the normal direction (height direction) of the plane of the optical disk300.

InFIG. 2A, reference numeral22denotes an auxiliary reference pin provided in the drive. When the inner case200is pulled out to the position indicated by the chain double-dashed line, the front end face of the inner case200is brought into contact with a side face of the auxiliary reference pin22, and thus a position of the inner case200in the plane parallel to the plane of the optical disk300is controlled by the auxiliary reference pin22in combination with the above-mentioned reference pin21. That is, through the use of the reference pin21and the auxiliary reference pin22, a position of the inner case200in the plane parallel to the plane of the optical disk300is controlled, thereby allowing the rotation of the inner case200in the plane to be controlled.

As described above, in the disk cartridge according to this embodiment, simply by pulling out the inner case200to a predetermined position, the V-shaped notch204provided in a portion on the front end face of the inner case200is brought into contact with the reference pin21, and the front end face of the inner case200is brought into contact with the auxiliary reference pin22. Therefore, positioning of the inner case200in the normal direction and the parallel direction with respect to the plane of the optical disk300can be performed with accuracy. Thus, unlike the case with the conventional disk cartridge, positioning does not require a disk cartridge or a drive to be moved in a normal direction with respect to a plane of an optical disk, thereby allowing the drive to be reduced in thickness (dimension in the normal direction of the optical disk).

InFIG. 2A, reference numeral23denotes a detection switch provided in the drive. When positioning is performed so that the inner case200is pulled out to the position indicated by the chain double-dashed line, the detection switch23detects a state of the write-protect identifying member500(position in the directions indicated by the arrow502).

In the disk cartridge according to this embodiment, the write-protect identifying member500is provided on the front end face of the inner case200, and therefore, simply by pulling out the inner case200to a predetermined position, a write-protect state can be detected Thus, unlike the case with the conventional disk cartridge, the detection of write protection does not require a detection switch provided in a drive or a disk cartridge to be moved in a normal direction with respect to a plane of an optical disk, thereby allowing the drive to be reduced in thickness (dimension in the normal direction of the optical disk).

In this disk cartridge, in a state where the inner case200is housed in the outer case100, the releasing lever404of the locking member400is pushed by a user using a sharp implement, and thus a lock is released, thereby allowing the inner case200to be pulled out from the outer case100. In this case, in order to prevent a complete pull-out of the inner case200from the outer case100that accidentally may cause the inner case200or the optical disk300to fall off, the claw portion209is provided in a corner portion of the rear end of the inner case200. As shown inFIG. 7, an inclined concave portion107is provided on an inner side wall near the opening101of the outer case100. In a position immediately before the inner case200is pulled out completely from the outer case100, as shown inFIG. 7, the claw portion209is engaged with the concave portion107. Therefore, the inner case200can be prevented from falling off from the outer case100, thereby allowing the improved safety to be achieved. On the other hand, when the inner case200is required to be pulled out completely from the outer case100for some reason, a sharp implement24is inserted into a through hole108provided on a side face of the outer case100. This alone is enough for the claw portion209to be deformed elastically, thereby disengaging the claw portion209from the concave portion107, so that the inner case200can be pulled out completely from the outer case100. After that, when the inner case is inserted back into the outer case100, since a recess of the concave portion107is formed in the shape of a wedge, while being deformed elastically, the claw portion209can be inserted without being engaged with the concave portion107. Thus, for example, in plants, it is made possible to exchange faulty optical disks and insert optical disks into cartridges after being assembled, and thus the degree of freedom in the manufacturing process can be increased, thereby allowing the productivity to be improved.

FIGS. 8Ato8F constitute a six-sided view of the disk cartridge according to this embodiment.FIGS. 8A,8B, and8C are a plan view, a left side view, and a side view of a rear portion, respectively.FIGS. 8D,8E, and8F are a side view of a front portion, a night side view, and a back face view, respectively. Hereinafter, the disk cartridge according to the present invention will be detailed further by referring to portions that have not been described yet, with reference to these figures.

In the figures, reference numeral109denotes an insertion error preventing groove that is provided on one side face of the outer case100(in this example, a right side face) so as to be parallel to a direction in which the disk cartridge is inserted into the drive (namely, the come-in/out directions of the inner case200with respect to the outer case100). An insertion error preventing projection that is allowed to slide within the groove109is provided near an entrance of the drive for disk cartridge insertion. When an attempt is made to insert the disk cartridge into the drive in an erroneous direction, the insertion error preventing projection collides with the disk cartridge so as to prevent the insertion of the disk cartridge.

Reference numeral110denotes a pull-out preventing groove that is provided in a direction orthogonal to the direction in which the disk cartridge is inserted into the drive (namely, the come-in/out directions of the inner case200with respect to the outer case100). At the time when the disk cartridge is being inserted into the drive or a stacker of a changer drive, a pull-out preventing mechanism that is provided in the drive or the stacker is engaged with the pull-out preventing groove110. As a result, for example, if the inner case200is in a state of being pulled out from the outer case100, pull-out of the disk cartridge from the stacker can be prevented mechanically from being caused accidentally.

Reference numeral111denotes a convex guide piece that is provided on each side face (left side face and right side face) of the outer case100so as to be parallel to the direction in which the disk cartridge is inserted into the drive (namely, the come-in/out directions of the inner case200with respect to the outer case100). The guide piece111has two opposed faces111aand111bthat are substantially parallel to the plane of the optical disk. In a direction orthogonal to a direction to which the guide piece111is extended, a distance between the two faces111aand111bis narrower than a thickness of the outer case100.

The following description is directed to a function of this guide piece111by referring to FIG.9. In the figure, reference numerals24and24adenote a stacker portion of a changer drive and a guide groove provided in the stacker portion24, respectively. When the disk cartridge is inserted into the stacker portion24, the convex guide piece111of the outer case100is allowed to slide within the guide groove24aof the stacker portion24. After the insertion, the guide piece111is fitted in the guide groove24a, and thus a position of the disk cartridge in the normal direction of the surface of the contained optical disk is controlled. If the two faces111aand111bconstituting the guide piece111are inclined with respect to the plane of the optical disk, a dimensional error in a height direction of the outer case100results in a positional shift of the disk cartridge in the normal direction of the plane of the optical disk. However, the two faces111aand111bof the guide piece111according to this embodiment are substantially parallel to the plane of the optical disk, and thus, regardless of whether or not the outer case100has a dimensional error in the height direction of the outer case100, a position of the disk cartridge in the normal direction of the plane of the optical disk with respect to the stacker portion24is controlled with accuracy.

Moreover, a width of the convex guide piece111(distance between the two faces111aand111b) is smaller than the thickness of the outer case100, and thus as shown in the figure, disk cartridges can be arranged in close contact with each other in the stacker portion24. This indicates that a plurality of disk cartridges joined to each other, e.g. bonded using a double-faced adhesive tape6, also can be inserted into the stacker portion24in that state. A single-disk cartridge10as shown inFIG. 10A, and two coupled disk cartridges11that are bonded to each other in the same orientation using a double-faced adhesive tape6as shown inFIG. 10Balso can be housed in the stacker portion24in the respective states. Therefore, in the case where it is convenient to handle a plurality of disk cartridges as a set, for example, a two-disk set or a three-disk set, it is made possible to handle these disk cartridges always as one body, thereby considerably increasing the convenience of handling a plurality of disks. Further, the disk cartridges can be housed in close contact with each other in the stacker portion24, thereby maximizing the efficiency of housing disk cartridges in the stacker portion24. In a conventional method of handling a plurality of disk cartridges as a set, a joining member is used to join the disk cartridges to each other. However, a size reduction of a disk cartridge results in an excessive size reduction of a joining member, and thus a joining operation may be hindered and the joining member becomes more likely to be lost. In this embodiment, the disk cartridges may be joined to each other simply by using a double-faced adhesive tape, thereby allowing these problems in the conventional technique to be solved. A joining means that can be used is not limited to the double-faced adhesive tape6and for example, may be formed of a glue or an adhesive.

Referring back toFIG. 8, reference numeral112denotes an area (label area) on which a label is attached. Information recorded on the optical disk and the like is written on the label. This disk cartridge does not include a shutter, and thus a large area can be secured as the label area. The disk cartridge also can be used optimally for ROM disks.

Reference numeral113denotes a detection hole for detecting a type of an optical disk. The detection hole113is provided near a front end of the side face (in this example, the left side face) of the outer case100. A forming position, a size and the like of the detection hole113are determined according to information regarding a contained optical disk (for example, information regarding a ROM disk, a recordable disk, a type of a medium or the like). According to this configuration, at a point in time when a disk cartridge is inserted into a holder of a drive or a stacker of a changer drive (that is, before the inner case200is pulled out from the outer case100), information regarding a contained optical disk can be detected. Thus, disk controlling information can be detected at an early point in time, thereby achieving a quick start-up.

Reference numeral211denotes a sub label area that is provided on the cover208of the inner case200. For example, the above-mentioned information regarding the contained optical disk or the like may be recorded on a label in the form of a bar code or the like, and the label is attached on the sub label area211. Thus, without the use of the detection hole113, during a loading operation of the disk cartridge, disk controlling information regarding the contained optical disk can be detected, thereby allowing the same effect as that in the case of using the above-mentioned detection hole113to be attained. A method of recording disk controlling information is not limited to a method using a bar code. Other recording methods also may be employed.

FIGS. 11Ato11C are perspective views of the disk cartridge according to Embodiment 1 of the present invention.FIG. 1Ashows a state in which the inner case200is housed completely in the outer case100,FIG. 11Bshows a state in which the inner case200is pulled out from the outer case100so that the optical disk300is housed in the outer case100by not less than half the size of the optical disk300, andFIG. 11Cshows a state in which the inner case200is pulled out from the outer case100so that the optical disk300is exposed outside the outer case100by not less than half the size of the optical disk300.

FIG. 11Bshows a pull-out state of the inner case200when the disk cartridge is loaded into a drive of a type into which a single disk cartridge is loaded (single-disk drive) such as a drive of a notebook personal computer or a PDA. In this case, while a pull-out amount of the inner case200is reduced to a small value, the cutouts104of the outer case100, the cutout203of the inner case200and the cover208form apertures in which the optical disk300is exposed, and through these apertures, a turntable of a spindle motor, a clamper, an optical head and a magnetic head that are provided in the drive can be moved toward the optical disk300.

FIG. 11Cshows a pull-out state of the inner case200when the disk cartridge mounted in a changer drive is loaded into a drive unit. Similarly, in this case, the cutouts104of the outer case100, the cutout203of the inner case200and the cover208form apertures in which the optical disk300is exposed, and through these apertures, a turntable of a spindle motor, a clamper, an optical head and a magnetic head can be moved toward the optical disk300.

Next, a configuration of a single-disk drive into which the disk cartridge according to the present invention is loaded will be described with reference toFIGS. 12Ato FIG.14.

FIGS. 12Ais a plan view showing a state in which the disk cartridge according to the present invention is loaded into the single-disk drive, andFIG. 12Bis a cross sectional view taken on line XIIB—XIIB of FIG.12A.

InFIGS. 12A and 12B, reference numerals21,22and23denote a reference pin, an auxiliary reference pin, and a detection switch for detecting the write-protect identifying member500, respectively. These components are the same as those described with reference to FIG.2A. The movements of the pull-out pin20along the arrows20aand20bthat were described with reference toFIG. 2Aare realized by a pull-out driving mechanism29composed of a driving motor29a, a feed screw29b, and a cranking mechanism29c.FIG. 12Ashows a state in which the inner case200is pulled out to a position indicated by the chain double-dashed line shown inFIG. 2Ausing the pull-out pin20, which is the same as the state shown in FIG.11B.

When viewed from the normal direction of the optical disk300, the circular arc102forming the substantially V-shaped cutout104of the outer case100substantially coincides with a portion of the circular arc201forming the substantially U-shaped cutout203of the inner case200. The straight line103forming the substantially V-shaped cutout104substantially coincides with one of the pair of the straight lines202forming the substantially U-shaped cutout203. As a result, on an upper side above the optical disk300, the optical disk300is exposed from an aperture formed by the substantially V-shaped cutout104of the outer case100and the cover208of the inner case200. On a lower side below the optical disk300, the optical disk300is exposed from an aperture formed by the substantially V-shaped cutout104of the outer case100and the U-shaped cutout203of the inner case200. Through the aperture on an upper surface side of the optical disk300, a damper28and a magnetic head27are inserted. Through the aperture on a lower surface side of the optical disk300, a turntable25aof a spindle motor25and an optical head26are inserted. The magnetic head27and the optical head26are moved as a unit parallel to the straight lines103and202, namely, in a radial direction of the optical disk300by a feeding mechanism30that is composed of a feeding motor and a feed screw. Thus, recording and/or reproduction is performed with respect to the optical disk300.

As described above, even when a pull-out amount of the optical disk300from the outer case100is reduced to an amount as small as less than half the diameter of the optical disk300, recording and/or reproduction can be performed, thereby allowing a single-disk drive to be reduced in depth dimension (dimension in the pull-out direction of the inner case200).

FIGS. 12A and 12Bshowed an example in which a magneto-optical head composed of the optical head26and the magnetic head27was moved rectilinearly in the radial direction of the optical disk300. However, as shown inFIGS. 13A and 13B, a configuration also is possible in which the magneto-optical head is rotated about a shaft26a. In the disk cartridge according to this embodiment, the straight line103forming the substantially V-shaped cutout104and the pair of straight lines202forming the substantially U-shaped cutout203are inclined with respect to four sides of the rectangular inner case200. This allows the shaft26aas a rotation center of the magneto-optical head of a rotary type to be disposed in a position other than four corner portions of the inner case200. Thus, it is possible to use a rotary type magneto-optical head that can be used suitably for the realization of high-speed access, thereby improving the degree of design freedom of a magneto-optical head.

When the inner case200is pulled out so as to be in the state shown byFIGS. 12A,12B,13A and13B, a center portion of the optical disk300on each surface is exposed. Therefore, clamping of the optical disk300can be performed by a mechanical clamping method in which an optical disk is held from both sides, or a magnetic clamping method in which an attracting plate attached to an optical disk is attracted magnetically from one side. Further, a recording/reproducing head also is not limited to the head for magneto-optical disks that requires each surface of an optical disk to be used. It also is possible to use a head for phase-change disks that only requires one surface of an optical disk to be used.

FIG. 14shows an external view showing a typical configuration of a single-disk drive. In the figure, reference numerals10and40denote the disk cartridge according to the present invention and a single-disk drive, respectively. By the disk cartridge10according to the present invention, a thin single-disk drive of a slot-in loading type that is reduced in depth dimension can be realized.

With reference toFIGS. 15A and 15BandFIG. 16, the description is directed next to a configuration of a changer drive that is used in an AV library or an AV server.

FIG. 15Ais a front view showing a pull-out state of the inner case200of the disk cartridge according to the present invention that is loaded into the changer drive.FIG. 15Bis a cross sectional view taken on line XVB—XVB of FIG.15A. Further,FIG. 16is a schematic perspective view showing a configuration of the changer drive in which the disk cartridge according to the present invention is mounted.

A spindle motor25for rotating the optical disk300is required to be disposed at a center of the optical disk300. Therefore, as shown inFIGS. 15A and 15B, the inner case200is pulled out from the outer case100so that the contained optical disk300is exposed outside the outer case100by not less than half the size of the optical disk300. Thus, all constituent elements of a drive unit including the spindle motor25, a magneto-optical head composed of an optical head26and a magnetic head27, a feeding mechanism30for moving the magneto-optical head and the like can be disposed on a side opposite the outer case100with respect to the opening101of the outer case100(right side of a chain double-dashed line101a). As a result, as shown inFIG. 16, a changer drive can be realized in which a stacker24for housing disk cartridges is disposed on a side of a user, and on a rear side of the stacker24, a drive unit35is disposed that moves in arranging directions35aof the disk cartridges. The drive unit35moves to a position of a selected disk cartridge, and pulls out the inner case200as shown inFIGS. 15A and 15Bby a mechanism to pull out the inner case200that is provided in the drive unit35. Thus, recording and/or reproduction can be performed with respect to the optical disk300.

In this changer drive, as in the case of housing books in a bookcase, the disk cartridges can be loaded in close contact with each other into the stacker24. Therefore, an increased number of cartridges can be housed in the stacker24. Further, in addition to a single disk cartridge10, a plurality of disk cartridges11that are bonded to each other using a double-faced adhesive tape or the like also can be inserted into the stacker24in that state. As a result, the convenience of handling a plurality of disks such as in the form of a two-disk set or the like can be increased considerably.

With the following limiting conditions regarding a type of an optical disk and a clamping method, the disk cartridge according to the present invention can be configured as shown in FIG.17andFIGS. 18Ato18C.

A first limiting condition is defined as a case where disk clamping is performed by a magnetic clamping method (method in which an attracting plate is attached to an optical disk). In a structure according to this clamping method, an optical disk is not held between a damper and a turntable of a spindle motor. Thus, in this case, space for clamping needs to be secured only on one side of an optical disk.

A second limiting condition is defined as a case where an optical disk is of a reflective optical disk such as a CD or a phase-change disk. In the case of using an optical head for reflective optical disks, unlike a magneto-optical head for magneto-optical disks, it is not necessary to use a magnetic head that is disposed on a side opposed to the optical head through the medium of an optical disk. Thus, space in which the optical head is disposed needs to be secured only on one side of an optical disk.

FIG. 17is an exploded perspective view showing constituent components of a disk cartridge according to Embodiment 2 of the present invention. The disk cartridge is configured so as to correspond to the above-mentioned two limiting conditions.

In an outer case100, a substantially V-shaped cutout104formed by a circular arc102having a radius larger than a radius of a spindle motor and an inclined straight line103that is connected to the circular arc102is provided only on a lower side plate100bof the outer case100, and on a upper side plate100a, a straight line portion120is provided instead of the substantially V-shaped cutout104.

In an inner case200, since the substantially V-shaped cutout104is not formed on the upper side plate100aof the outer case100, a cover208(seeFIG. 1) to be fitted in the cutout104is not necessary. However, in order to prevent an optical disk300housed in a concave portion230from coming out, a projection215is provided so as to be opposed to and away from a bottom face of the concave portion230. When the inner case200is housed in the outer case100, as shown inFIG. 18A, the projection215is housed inside the outer case100. Further, as shown inFIG. 17, by providing a bridging portion212on an opening side of a substantially U-shaped cutout203that is provided on the inner case200, the inner case200can be increased in strength. This is made possible because this embodiment does not require a magnetic head (the magnetic head27shown in FIGS.12A and12B), and thus it is no longer necessary to consider interference with the magnetic head.

In the optical disk300, it is essential that an attracting plate302is provided in a center portion.

The disk cartridge according to this embodiment has the same configuration as that of the disk cartridge according to Embodiment 1 except for the difference mentioned above. In the following description, like reference numerals denote like members having the same functions as those described with regard to Embodiment 1, for which descriptions do not go into details.

FIG. 18shows perspective views of the disk cartridge according to Embodiment 2 of the present invention.FIG. 18Ashows a state where the inner case200is housed completely in the outer case100,FIG. 18Bshows a state where the inner case200is pulled out from the outer case100so that the optical disk300is housed in the outer case100by not less than half the size of the optical disk300, andFIG. 18Cshows a state where the inner case200is pulled out from the outer case100so that the optical disk300is exposed outside the outer case100by not less than half the size of the optical disk300. As in Embodiment 1,FIG. 18Bshows a pull-out state of the inner case200when recording and/or reproduction is performed in a single-disk drive, andFIG. 18Cshows a pull-out state of the inner case200when recording and/or reproduction is performed in a changer drive.

According to the disk cartridge of Embodiment 2, since the substantially V-shaped cutout104is required to be formed only on the lower side plate100bof the outer case100and not on the upper side plate100aof the outer case100, on the entire surface of the upper side plate100a, patterns and characters can be provided, and a label can be attached. Thus, a disk cartridge can be configured that achieves excellent properties in terms of the appearance or practical use.

Furthermore, since the cutout104is not formed on the upper side plate100aof the outer case100, it is not necessary to provide the cover208(seeFIG. 1) to be fitted in the cutout104on an upper surface of the inner case200. As a result, the small projection215is used to prevent the optical disk from coming out, so that a size reduction can be achieved for this element. Thus, the inner case200can be formed as one body more easily, thereby achieving excellent properties from the industrial viewpoint.

In each of Embodiments 1 and 2 described above, the substantially V-shaped cutout104was formed by the circular arc102and the straight line103, and the substantially U-shaped cutout203was formed by the circular arc201and the two straight lines202parallel to each other. However, the present invention is not limited thereto. It is not necessarily required that the circular arcs102and201have the shape of a circular arc in the strict sense. Further, each of the straight lines103and202may be curved slightly, or may be a straight line to which another straight line or curve is connected. Further, the substantially V-shaped cutout104may be formed by, in addition to the circular arc102and the straight line103connected to one end of the circular arc102, a straight line or curve that is connected the other end of the circular arc102. Further, it is not necessarily required that the two straight lines202forming the substantially U-shaped cutout203be parallel to each other in the strict sense. It also is not necessarily required that the straight line103and the straight line202be parallel to each other in the strict sense, and for example, one of them may be inclined slightly with respect to the other. Further, the expressions “substantially V-shaped” and “substantially U-shaped” were used only for schematically representing the respective shapes of the cutouts. Modifications of the cutouts having the shapes described with regard to the above-mentioned embodiments are possible within the scope of the intended meaning of the present invention.