Abstract:
A disk unit is disclosed wherein a disk inserted by a pivoting arm is loaded to the interior of the disk unit or a disk accommodated in the interior of the disk unit is unloaded to the exterior of the disk unit, the disk unit including a plurality of arms able to convey two types of disks different in diameter while supporting an outer periphery edge of each of the disks.

Description:
BACKGROUND  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a disk unit for driving an optical disk (e.g., CD-R/RW, DVD-R/-RW/RAM/+R/+RW) as a recording medium which stores a large amount of information in information systems such as various computer systems.  
         [0003]     2. Description of the Prior Art  
         [0004]     The disk unit incorporated for example in a personal computer is usually provided with a disk tray loaded with a disk, the disk tray being constructed so as to move forward and backward. The disk loaded on the disk tray is driven within a body of the disk unit to perform read or write of information.  
         [0005]     On the other hand, as a disk unit not using such a disk tray, a slot-in type disk unit tends to be adopted more and more. The slot-in type disk unit is suitable for the reduction in thickness and size of personal computers. In the slot-in type disk unit, the disk tray is not used for load and unload of a disk with respect to the unit body, so when an operator inserts the greater part of the disk into a slot, a loading mechanism installed in the unit body operates and loads the disk automatically.  
         [0006]      FIGS. 49 and 50  show the construction and operation modes of a loading mechanism in a conventional slot-in type disk unit. According to the illustrated construction, when an operator inserts a disk D into a slot, the disk D reaches its position shown in  FIG. 49  while its height direction and right and left positions are restricted by a pin  100   a  provided at a tip of a first pivotable member  100  and also by right and left guide members  101 ,  102  and further restricted halfway by a pin  103   a  provided at a tip of a second pivotable member  103 .  
         [0007]     At this time, the pin  100   a  at the tip of the first pivotable member  100  is pushed by the disk D and the first pivotable member  100  rotates in the direction of arrow  100 A. Likewise, the pin  103   a  at the tip of the second pivotable member  103  is pushed by the disk D and the second pivotable member  103  rotates in the direction of arrow  103 A. Further, a switch lever  104  is pushed against an end portion of the second pivotable member  103  and rotates in the direction of arrow  104 A, thereby actuating a detection switch  105 .  
         [0008]     Upon operation of the detection switch  105 , drive means  106  starts operating and a first slide member  107  starts moving in the direction of arrow  107 A. An end of the first slide member  107  and an end of a second slide member  108  are connected together through a slide connecting member  109  which is pivotably supported by a pin  110 . Consequently, the second slide member  108  moves forward in the direction of arrow  108 A in synchronism with retreat of the first slide member  107 .  
         [0009]     Once the first slide member  107  starts to retreat, a driven pin  100   b  of the first pivotable member  100  which is cantilevered by the first slide member  107  is guided by a cam groove  107   a  of the first slide member  107 , so that the pivotable member  100  rotates in the direction of arrow  108 B around a fulcrum  100   c , whereby the pin  100   a  at the tip of the first pivotable member  100  conveys the disk D until abutment against pins  111   a  and  111   b  of a disk positioning member  111  in the direction of arrow  107 A.  
         [0010]     At this time, the pin  103   a  of the second pivotable member  103  rotates in the direction of arrow  103 A and therefore moves in the arrow  103 A direction in synchronism with the pin  100   a  provided at the tip of the first pivotable member  100  while supporting the disk D. Then, after abutment of the disk D against the pins  111   a  and  111   b  of the disk positioning member  111 , the pin  103   a  rotates to a position spaced a little from the disk D.  
         [0011]     The above is an operation mode of the loading mechanism in case of loading the disk D into the disk unit. The operation mode of the loading mechanism in case of unloading the disk D to the exterior of the disk unit is reverse to the above operation mode. More specifically, when the drive means  106  is turned ON in the opposite direction in accordance with an unloading command in a state in which the disk D is at a predetermined position in the interior of the disk unit as shown in  FIG. 50 , the first slide member  107  starts to move forward in the direction of arrow  107 B and, in synchronism therewith, the second slider member  108  connected to the slide connecting member  109  starts to retreat in the direction of arrow  108 B. Consequently, the first pivotable member  100  rotates in the direction of arrow  100 A and the second pivotable member  103  rotates in the direction of arrow  103 B, so that the disk D is unloaded to the exterior of the disk unit while being supported by the pins  100   a  and  103   a  provided respectively at the tips of those pivotable members.  
         [0012]     The disk D loaded into the disk unit is clamped by a clamp head  112  which is adapted to move vertically at a predetermined position. The clamp head  112  is integral with a turntable  113  fixed to a drive shaft of a spindle motor  114 . The spindle motor  114  is disposed on a frame member (not shown), which frame member is moved vertically by a lift mechanism (see, for example, Japanese Patent Laid-Open Publication No. 2002-117604).  
         [0013]     In the disk unit configured as above, in order to effect a cooperative operation of both first pivotable member  100  and second pivotable member  103 , the first slide member  107  and the second slide member  108  are connected with each other through the slide connecting member  109  so as to synchronize their forward and backward movements. Therefore, the positions in the course of conveyance of the pins  100   a  and  103   a  provided respectively at the tips of the first and second pivotable members  100 ,  103  must be determined on the basis of an outer periphery edge of a disk of a specific diameter.  
         [0014]     Disks defined by the standard applied to such a disk unit as the above disk unit are generally called 12 cm disk and 8 cm disk, the former being the highest in versatility. Driving a disk of such a different diameter in a disk tray type disk unit can be done by only loading the disk to a corresponding groove formed in a disk tray. However, in the disk unit having such a mechanism as disclosed in Japanese Patent Laid-Open Publication No. 2002-117604, a pivoting range of the first pivotable member  100  and that of the second pivotable member  103  are designed in a corresponding relation to the conveyance of the 12 cm disk, so that the conveyance and hence drive of the 8 cm disk cannot be done at all.  
       SUMMARY  
       [0015]     This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.  
         [0016]     The present invention has been accomplished in view of the above conventional problems and it is an object of the present invention to provide a slot-in type disk unit which permits drive of two types of disks different in diameter and in which the tip of an arm for the conveyance of a disk is prevented from damaging an optical pickup adapted to write or read information with respect to the disk.  
         [0017]     The present invention achieves the above-mentioned object by adopting the following means.  
         [0018]     In a first aspect of the present invention there is provided a disk unit wherein a disk inserted by a pivoting arm is loaded to the interior of the disk unit or a disk accommodated in the interior of the disk unit is unloaded to the exterior of the disk unit, the disk unit including a plurality of arms able to convey two types of disks different in diameter while supporting an outer periphery edge of each of the disks.  
         [0019]     In a second aspect of the present invention there is provided, in combination with the above first aspect, a disk unit wherein the plural arms can convey the two types of disks different in diameter while supporting the outer periphery edge of each of the disks in at least three positions.  
         [0020]     In a third aspect of the present invention there is provided, in combination with the above first aspect, a disk unit wherein the drive of the plural arms is controlled in interlock with advance or retreat of a single loading slider.  
         [0021]     In a fourth aspect of the present invention there is provided, in combination with the above first aspect, a disk unit wherein an arm for the conveyance of a small-diameter disk is retracted from a conveyance path of a large-diameter disk, thereby permitting conveyance of the large-diameter disk.  
         [0022]     In a fifth aspect of the present invention there is provided, in combination with the above first aspect, a disk unit wherein an arm for the conveyance of a small-diameter disk is disposed so as not to extend onto a lift base on which is provided a turntable for supporting and rotating the disks.  
         [0023]     In a sixth aspect of the present invention there is provided, in combination with the above first aspect, a disk unit wherein an automatic loading of a small-diameter disk is started on the basis of a primary operation of a detection switch adapted to judge the state of operation of the disk supporting arms and an automatic loading of a large-diameter disk is started on the basis of a secondary operation of the detection switch.  
         [0024]     In a seventh aspect of the present invention there is provided, in combination with the above first aspect, a disk unit wherein a loading member for transmitting a driving force to at least one of the plural arms is provided with a guide groove to control the drive of an arm for the conveyance of a large-diameter disk and a guide groove to control the drive of an arm for the conveyance of a small-diameter disk.  
         [0025]     In an eighth aspect of the present invention there is provided, in combination with the above first aspect, a disk unit wherein a common arm is guided by either a guide groove provided to control the drive of an arm for the conveyance of a large-diameter disk or a guide groove provided to control the drive of an arm for the conveyance of a small-diameter disk.  
         [0026]     In a ninth aspect of the present invention there is provided, in combination with the above first aspect, a disk unit wherein an arm driven pin guided by a guide groove adapted to control the drive of an arm for the conveyance of a large-diameter disk and a guide groove adapted to control the drive of an arm for the conveyance of a small-diameter disk faces the guide groove adapted to control the drive of the arm for the conveyance of the small-diameter disk in a steady state and, upon insertion of the large-diameter disk, faces the guide groove adapted to control the drive of the arm for the conveyance of the large-diameter disk.  
         [0027]     In a tenth aspect of the present invention there is provided, in combination with the above first aspect, a disk unit wherein a loading member for transmitting a driving force to at least one of the plural arms is provided with a guide groove adapted to make the one arm perform an operation for the conveyance of a large-diameter disk and a guide groove adapted to make the one arm perform an operation for the conveyance of a small-diameter disk.  
         [0028]     In an eleventh aspect of the present invention there is provided, in combination with the above first aspect, a disk unit wherein a turntable for supporting and rotating the disks is provided on a lift frame, and at a tip of an arm passing over an optical pickup which is adapted to reciprocate through the interior of the lift frame there is provided a descent inhibiting member for the arm.  
         [0029]     In a twelfth aspect of the present invention there is provided, in combination with the above eleventh aspect, a disk unit wherein a pin member is fixed to a rear portion of a disk support member fixed to the tip of the arm and is allowed to serve as the descent inhibiting member.  
         [0030]     In a thirteenth aspect of the present invention there is provided, in combination with the above eleventh aspect, a disk unit wherein a disk support member and the descent inhibiting member are formed integrally and fixed to the tip of the arm.  
         [0031]     According to the present invention it is possible to complete a slot-in type disk unit able to effect automatic loading and drive of two types of disks different in diameter. Besides, since the drive of plural arms is controlled, the thickness of the entire unit does not become large and thus it is possible to meet the demand for thickness reduction. Further, the tip of an arm adapted to pivot over an optical pickup which is for write or read of information with respect to a disk and thereby effect conveyance of the disk is prevented from damaging the optical pickup, whereby the mechanical reliability of the disk unit can be improved. 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0032]     The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:  
         [0033]      FIG. 1  is a perspective view of a slot-in type disk unit embodying the present invention;  
         [0034]      FIG. 2  is a perspective view showing an interior configuration of the disk unit of  FIG. 1 ;  
         [0035]      FIG. 3  is a perspective view showing the construction of a drive mechanism in the disk unit of  FIG. 1 ;  
         [0036]      FIG. 4  is an exploded perspective view showing the construction of a loading slider;  
         [0037]      FIG. 5  is an exploded perspective view showing the construction of both loading slider and guide plate;  
         [0038]      FIG. 6  is an exploded perspective view showing the construction of a power transfer mechanism;  
         [0039]      FIG. 7  is an exploded perspective view showing the construction of a gear disc;  
         [0040]      FIG. 8  is a perspective view showing the construction of a rack slider;  
         [0041]      FIG. 9  is a first process diagram illustrating in what state a large-diameter disk is conveyed;  
         [0042]      FIG. 10  is a second process diagram illustrating in what state the large-diameter disk is conveyed;  
         [0043]      FIG. 11  is a third process diagram illustrating in what state the large-diameter disk is conveyed;  
         [0044]      FIG. 12  is a fourth process diagram illustrating in what state the large-diameter disk is conveyed;  
         [0045]      FIG. 13  is a fifth process diagram illustrating in what state the large-diameter disk is conveyed;  
         [0046]      FIG. 14  is a sixth process diagram illustrating in what state the large-diameter disk is conveyed;  
         [0047]      FIG. 15  is a seventh process diagram illustrating in what state the large-diameter disk is conveyed;  
         [0048]      FIG. 16  is a first process diagram illustrating in what state the large-diameter disk is conveyed;  
         [0049]      FIG. 17  is a second process diagram illustrating in what state the large-diameter disk is conveyed;  
         [0050]      FIG. 18  is a third process diagram illustrating in what state the large-diameter disk is conveyed;  
         [0051]      FIG. 19  is a fourth process diagram illustrating in what state the large-diameter disk is conveyed;  
         [0052]      FIG. 20  is a fifth process diagram illustrating in what state the large-diameter disk is conveyed;  
         [0053]      FIG. 21  is a sixth process diagram illustrating in what state the large-diameter disk is conveyed;  
         [0054]      FIG. 22  is a seventh process diagram illustrating in what state the large-diameter disk is conveyed;  
         [0055]      FIG. 23  is a first process diagram illustrating in what state a small-diameter disk is conveyed;  
         [0056]      FIG. 24  is a second process diagram illustrating in what state the small-diameter disk is conveyed;  
         [0057]      FIG. 25  is a third process diagram illustrating in what state the small-diameter disk is conveyed;  
         [0058]      FIG. 26  is a fourth process diagram illustrating in what state the small-diameter disk is conveyed;  
         [0059]      FIG. 27  is a fifth process diagram illustrating in what state the small-diameter disk is conveyed;  
         [0060]      FIG. 28  is a sixth process diagram illustrating in what state the small-diameter disk is conveyed;  
         [0061]      FIG. 29  is a seventh process diagram illustrating in what state the small-diameter disk is conveyed;  
         [0062]      FIG. 30  is a first process diagram illustrating in what state the small-diameter disk is conveyed;  
         [0063]      FIG. 31  is a second process diagram illustrating in what state the small-diameter disk is conveyed;  
         [0064]      FIG. 32  is a third process diagram illustrating in what state the small-diameter disk is conveyed;  
         [0065]      FIG. 33  is a fourth process diagram illustrating in what state the small-diameter disk is conveyed;  
         [0066]      FIG. 34  is a fifth process diagram illustrating in what state the small-diameter disk is conveyed;  
         [0067]      FIG. 35  is a sixth process diagram illustrating in what state the small-diameter disk is conveyed;  
         [0068]      FIG. 36  is a seventh process diagram illustrating in what state the small-diameter disk is conveyed;  
         [0069]      FIG. 37  is a process diagram illustrating an ascending process of a lift frame;  
         [0070]      FIG. 38  is a process diagram illustrating a descending process of the lift frame;  
         [0071]      FIG. 39  is a diagram illustrating operation modes of the gear disc;  
         [0072]      FIG. 40  is a process diagram illustrating operation modes of arms during conveyance of the large-diameter disk;  
         [0073]      FIG. 41  is a process diagram illustrating operation modes of a loading arm;  
         [0074]      FIG. 42  is a process diagram illustrating operation modes of the loading slider and a driven pin;  
         [0075]      FIG. 43  is a process diagram showing in what state a lock lever functions;  
         [0076]      FIG. 44  is a diagram illustrating an operation mode of a guide arm;  
         [0077]      FIG. 45  is a diagram illustrating a state of occurrence of an inconvenience in  FIG. 44 ;  
         [0078]      FIG. 46  is a diagram illustrating an operation mode of an improved guide arm according to the present invention;  
         [0079]      FIG. 47  is a diagram illustrating a function of the guide arm shown in  FIG. 46 ;  
         [0080]      FIG. 48  is a perspective view showing another construction example of a descent inhibiting member;  
         [0081]      FIG. 49  is a plan view showing a conventional disk unit; and  
         [0082]      FIG. 50  is a plan view showing the conventional disk unit. 
     
    
     DETAILED DESCRIPTION  
       [0083]     Embodiments of the present invention will be described in detail hereinafter with reference to the accompanying drawings. To facilitate understanding of the present invention, constructions related to the gist of the present invention will be included in the following description.  
         [0084]      FIG. 1  illustrates an appearance of a slot-in type disk unit  1  embodying the present invention. An aperture  2   a  is formed centrally of a top plate of a chassis case  2  which is constructed in a shielded condition, and an inwards projecting protuberance  2   b  is formed on a periphery edge portion of the aperture  2   a . A bezel  3  is fixed to a front end of the chassis case  2 , and a slot  3   a  for insertion therein of both 12 cm disk (hereinafter referred to as the “large-diameter disk”) D 1  and 8 cm disk (hereinafter referred to as the “small-diameter disk”) D 2 , as well as through holes  3   b  and  3   c  for emergency release, are formed in the bezel  3 . The bezel  3  is provided with a push-button  4  for unloading the large-diameter disk D 1  or the small-diameter disk D 2  accommodated within the disk unit  1  to the exterior of the unit and an indicator  5  for indicating a state of operation of the disk unit  1 .  
         [0085]      FIG. 2  is a perspective view of the disk unit with a top plate portion of the chassis case  2  removed. A base panel  6  is disposed within the chassis case  2  and a drive unit A for the large- and small-diameter disks D 1 , D 2  is disposed obliquely downward from the center of the base panel  6 . In the drive unit A, for clamping center holes D 1   a  and D 2   a  of the large- and small-diameter disks D 1 , D 2 , or for releasing the clamped state, a lift frame  7  is connected at plural positions to the base panel  6  by a known shock-absorbing support structure  8 , the lift frame  7  being constructed such that a rear end portion thereof positioned centrally of the disk unit is vertically pivotable with the front bezel  3  side as a fulcrum.  
         [0086]     In the rear end portion of the lift frame  7 , a clamp head  9  is disposed at a position corresponding to the center of the large- or small-diameter disk D 1  or D 2  which has been loaded and stopped. The clamp head  9  is constructed integrally with a turntable  10  and is fixed to a drive shaft of a spindle motor  11  disposed just under the clamp head. The large- or small-diameter disk D 1  or D 2  clamped by a chucking pawl  9   a  of the clamp head  9  is driven rotationally by the spindle motor  11  to read or write information.  
         [0087]     The reference numeral B denotes a head unit supported by the lift frame  7 . In the head unit B, a carrier block  13  for reciprocating an optical pickup  12  in the diametrical direction of the large- and small-diameter disks D 1 , D 2  is supported at both ends thereof by guide shafts  14  and  15  which are fixed to the lift frame  7 . The carrier block  13  is moved forward and backward with a driving force of a sled motor  16  transmitted from a gear train  17  to a screw shaft  18  (see  FIG. 3 ).  
         [0088]     Plural arms for loading and unloading of the large- and small-diameter disks D 1 , D 2  are disposed on a flat surface of the base panel  6  in a surrounding relation to the lift frame  7  and are operated by a drive mechanism disposed on the back side of the base panel  6 . Among the plural arms, it is a disk supporting arm  19  that fulfills a main function in loading and unloading of the disks. The disk supporting arm  19  is adapted to move pivotally about a rivet pin  20  and not only supports rear end sides of the large- and small-diameter disks D 1 , D 2  but also keeps accurately the height position of each disk during conveyance. To this end, the disk supporting arm  19  is provided at a tip thereof with a holder  21 , and the rear end sides of the large- and small-diameter disks D 1 , D 2  are held by a recess  21   a  of the holder  21 .  
         [0089]     The reference numeral  22  denotes a loading arm for loading the large-diameter disk D 1  into the disk unit. The loading arm  22  is pulled by a link lever  24  which is connected to the loading arm through a pivot pin  23  and moves pivotally. The loading arm  22  starts pressing a front side portion with respect to the center of the large-diameter disk D 1  which has been inserted by a loading roller  22   a  of the loading arm, and functions to lead the large-diameter disk D 1  into the disk unit.  
         [0090]     A guide arm  25  is adapted to move pivotally about a pivot pin  26  which is mounted rotatably to the base panel  6 , and functions to support a side portion of the small-diameter disk D 2  and lead it to a predetermined position, the small-diameter disk D 2  being conveyed by a support member  25   a  which is fixed in a suspended state to a tip of the guide arm  25 . A guide arm  27  is adapted to move pivotally about a rivet pin  28  and not only functions to support a side portion of the large-diameter disk D 1  and lead it to a predetermined position, the large-diameter disk D 1  being conveyed by a support member  27   a  which is fixed in a suspended state to a tip of the guide arm  27 , but also functions to support a side portion of the small-diameter disk D 2  and lead it to a predetermined position. On the back side of the base panel  6 , an end portion of a third pivotable member  51  and an end portion of an extension spring  53  are attached to a pivot pin  27   b  provided at a base end portion of the guide arm  27 .  
         [0091]     A guide arm  29  is adapted to move pivotally about a rivet pin  30  and not only functions to support a side portion of the small-diameter disk D 2  and lead it to a predetermined position, the small-diameter disk D 2  being conveyed by a support member  29   a  which is fixed in an erected state to a tip of the guide arm  29 , but also functions to support a side portion of the large-diameter disk D 1  and locate it to a predetermined positions. A work pin  33   a  of a link lever  33  which is urged by an extension spring  31  and moves pivotally about a rivet pin  32  is engaged in a slit  29   e  of the guide arm  29 , so that the tip of the guide arm  29  assumes a constantly urged state in the centripetal direction. A guide arm  35  connected through a driven pin  35   b  to a guide groove  29   c  formed in a rear end portion of the guide arm  29  is adapted to move pivotally about a rivet pin  36  and not only functions to support the rear end side of the small-diameter disk D 2  through a support member  35   a  which is fixed in an erected state to a tip of the guide arm  35  and lead it to a predetermined position but also functions to support a side portion of the small-diameter disk D 2  and locate it at a predetermined position.  
         [0092]     The reference numeral  37  denotes a lock lever, which is adapted to move pivotally about a rivet pin  38 , thereby permitting an angle  37   a  formed at a tip of the lock lever  37  to lock a tongue piece  29   b  provided at the tip of the guide arm  29 . The angle  37   a  formed at the tip of the lock lever  37  is urged constantly in the centripetal direction by a wire spring  39 , but usually a stopper  40  functions to let the lock lever  37  stand still at a predetermined position.  
         [0093]     The reference numeral  41  denotes a lead wire which is disposed along the lower side of the bezel  3 . An end portion of the lead wire  41  is connected to a rear end portion of the lock lever  37  and a retaining end portion  41   a  of the lead wire  41  is bent in an erected state and faces the slot  3   a  of the bezel  3 . Therefore, when the large-diameter disk D 1  is inserted from the slot  3   a , the retaining end portion  41   a  is pushed by a side portion of the large-diameter disk D 1 , with the result that the lead wire  41  moves sideways in parallel with the bezel  3 . Consequently, the lock lever  37  is pulled and the angle  37   a  formed at the tip of the lock lever moves pivotally in a centrifugal direction, whereby the tongue piece  29   b  of the guide arm  29  can be unlocked.  
         [0094]     As a mechanical element exposed onto the flat surface of the base panel  6 , the reference numeral  42   a  denotes a retaining tongue piece of a lever arm  42  (see  FIGS. 2 and 3 ), which functions to control the position of the guide arm  27 . As to an operation mode thereof, a detailed description will be given later. Reference numeral  71  denotes a clamp release pin for releasing the clamped state of the large- and small-diameter disks D 1 , D 2  by the clamp head  9 .  
         [0095]     Mechanical elements are constructed on the back side of the base panel  6  to operate the guide arms, etc. thus constructed on the flat surface of the base panel  6 . The disk unit  1  of the present invention is constructed so that all of operation controls related to the conveyance of the large- and small-diameter disks D 1 , D 2  can be completed by advance and retreat of a loading slider  43  which is disposed in a side portion of the interior of the disk unit and in the longitudinal direction as indicated in phantom line in  FIG. 3 . The following description is now provided about the construction of the loading slider  43  as a main mechanical element and also about mechanical elements whose operations are controlled by the loading slider  43 .  
         [0096]      FIG. 4  shows a state in which the loading slider  43  is overlooked in a direction opposed to the back side of the base panel  6 . As shown in the same figure, the loading slider  43  is formed in the shape of a pillar and a rack gear  43   a  is formed in a front end portion of the loading slider. On the other hand, in a rear end portion of the loading slider  43  is formed a guide groove  43   b , the guide groove  43   b  comprising an upper-end horizontal portion  43   b - 1 , a lower-end horizontal portion  43   b - 2  and an intermediate, stepped, vertical portion  43   b - 3  which are in communication with one another.  
         [0097]     A driven pin  45   a  of a first pivotable member  45  adapted to move pivotally about a rivet pin  44  is fitted in the upper-end horizontal portion  43   b - 1  and a driven pin  47   a  of a second pivotable member  47  adapted to move pivotally about a rivet pin  46  is fitted in the vertical portion  43   b - 3 . Further, a work pin  47   b  of the second pivotable member  47  is fitted in an end through hole  48   a  of a driven slider  48 .  
         [0098]     Guide grooves  43   c - 1  and  43   c - 2  are formed on both sides of a middle portion of the loading slider  43 . A rear end portion of the guide groove  43   c - 1  is formed with a slant face and front and rear ends of the guide groove  43   c - 2  are also inclined. A driven pin  29   d  of the guide arm  29  is mounted so as to be positioned in an opening of the inclined rear end portion of the guide groove  43   c - 2  in a most advanced state of the loading slider  43 .  
         [0099]     Reference numeral  43   d  denotes a guide groove adapted to pull the link lever  24  so as to operate the loading arm  22  in synchronism with conveyance of the large-diameter disk D 1 . As shown in  FIG. 5 , a guide slit  49   a  is formed in a guide plate  49  fixed to the base panel  6  at a position overlapping the guide groove  43   d . A driven pin  24   a  fixed to a tip of the link lever  24  is in an inserted state into both guide groove  43   d  and guide slit  49   a . Therefore, the guide groove  43   d  adapted to move forward and backward and the guide slit  49   a  lying at a fixed position operate on each other to control the operation of the driven pin  24   a.    
         [0100]     In a side portion of the loading slider  43  which side portion faces the lift frame  7  there is formed a cam groove  43   e  to vertically move the driven pin  7   a  which functions to raise and lower the lift frame  7 . The cam groove  43   e  comprises a lower portion  43   e - 1  for maintaining the lift frame  7  at a low position, a slant portion  43   e - 2  for raising or lowering the lift frame  7 , and a higher portion  43   e - 3  for maintaining the lift frame  7  at a high position, which are formed in series.  
         [0101]      FIG. 6  is an exploded perspective view of a power transfer mechanism as overlooked from a back side thereof, the power transfer mechanism being constructed in the rear portion of the interior of the disk unit. In the power transfer mechanism, a cam groove  48   c  is formed in the driven slider  48  to raise and lower a driven pin  7   b  which functions to raise and lower the lift frame  7 . The cam groove  48   c  comprises a lower portion  48   c - 1  for maintaining the lift frame  7  at a low position, a slant portion  48   c - 2  for raising or lowering the lift frame  7 , and a higher portion  48   c - 3  for maintaining the lift frame  7  at a high position, which are formed in series.  
         [0102]     A work pin  51   a  of the third pivotable member  51  adapted to move pivotally about a rivet pin  50  is fitted in an end through hole  48   b  of the driven slider  48 . An end portion  52   a  of a link wire  52  is fitted on the work pin  51   a  and an opposite end portion  52   b  of the link wire  52  is engaged in a through hole  45   b  of the first pivotable member  45 . The third pivotable member  51  is urged counterclockwise in  FIG. 6  by the extension spring  53 , but when the disk unit is not in operation, the third pivotable member  51  stands still at its predetermined position because the movement of the work pin  51   a  is restricted by the link wire  52 . Further, a work piece  48   d  for actuating the lever arm  42  is formed in a side portion of the end through hole  48   b.    
         [0103]     A link arm  54  is connected between the first pivotable member  45  and a gear disc which will be described later. The link arm  54  is constructed so that it can expand and contract by a combination of a first link arm  54   a  connected to the first pivotable member  45  through a connecting member  55  and a second link arm  54   b  urged by an extension spring  56 , thereby ensuring the safety of the mechanism during conveyance of the large- and small-diameter disks D 1 , D 2 .  
         [0104]      FIG. 7  is a perspective view of an end portion of the second link arm  54   b  as overlooked from the back side of the disk unit. In the same figure, a through hole  54   b - 1  formed in the second link arm  54   b , a through hole  19   b  formed in a rotary base  19   a  of the disk supporting arm  19 , and a through hole  59   a  formed in a gear disk  59 , are pivotally supported simultaneously by a pivot pin  57 . On the other hand, a center hole  19   c  of the disk supporting arm  19  and a center hole  59   b  of the gear disc  59  are supported simultaneously by the rivet pin  20  which is fixed at one end thereof to the base panel  6 . Further, a retaining piece  19   d  of the rotary base  19   a  faces a retaining window  59   c  of the gear disc  59  to provide an integral combination.  
         [0105]     A gear  59   d  is formed in part of an outer periphery edge of the gear disc  59  opposed to a side face of the chassis case  2 . In an outer periphery edge of the gear disk  59  opposite to the said outer periphery edge there are formed switch starting stepped portions  59   e  and  59   f . A limit switch  60 , which is turned ON by the switch starting stepped portions  59   e  and  59   f , is mounted on a wiring board (not shown) disposed on the bottom of the chassis case  2  and a switch knob  60   a  thereof is operated by the switch starting stepped portions  59   e  and  59   f.    
         [0106]     The above-described lever arm  42  is fixed so as to move pivotally about a rivet pin  61  and its retaining tongue piece  42   a  is allowed to face the surface of the base panel  6  from the opening of the base panel  6 . Further, a tip of a spring piece  42   b  is brought into contact with an opening wall  6   a  of the base panel  6  so that an urging force acting in the centrifugal direction is generated in a roller  42   c  provided at a tip of the lever arm  42 . According to this construction, the lever arm  42  stands still at its predetermined position when the roller  42   c  is in contact with a side wall of the driven slider  48 , but with a sliding motion of the driven slider  48 , the roller  42   c  is pressed by the work piece  48   d  of the driven slider, so that the lever arm  42  moves pivotally about the rivet pin  61  and the retaining tongue piece  42   a  moves in the centrifugal direction.  
         [0107]     Next, a description will be given about a mechanism for pivoting the guide arm  25 . The pivot pin  26  provided at a base end as a fulcrum of the guide arm  25  is extended to the back side of the base panel  6  and a roller supporting plate  62  is fixed to an end portion of the pivot pin  26 . Since an extension spring  63  is anchored in a stretched state to the roller supporting plate  62  as shown in  FIG. 3 , a clockwise urging force in the same figure is exerted on the guide arm  25 , so that the guide arm  25  tilts in the centripetal direction. As shown in  FIG. 8 , a double roller  64  disposed on the roller supporting plate  62  has a large-diameter portion  64   a  and a small-diameter portion  64   b  which are constructed coaxially with each other.  
         [0108]     In  FIG. 8 , a rack slider  65  disposed along an inner surface of a side wall of the chassis case  2  is provided with a rack gear  65   a  meshing with the gear  59   d  of the gear disc  59  and moves forward and backward in synchronism with rotation of the gear disc  59 . A lower guide piece  65   b  is formed on a lower side of an intermediate portion of the rack slider  65  and an upper guide piece  65   c  is formed on an upper side of the said intermediate portion. The lower guide piece  65   b  guides the large-diameter portion  64   a  of the double roller  64 , while the upper guide piece  65   c  guides the small-diameter portion  64   b.    
         [0109]     The mechanical elements thus constructed are operated with advance and retreat of the loading slider  43  and a drive mechanism for them is disposed in a corner portion of the back side of the disk unit as shown in  FIG. 3 . A loading motor  66  serves as a power source of the drive mechanism and a rotational force of a worm gear  67  of an output shaft of the loading motor  66  is transmitted successively from a gear smaller in diameter up to a gear larger in diameter while being reduced in speed by means of a gear train comprising double gears  68 ,  69  and  70 . A driving force is transmitted to the rack gear  43   a  of the loading slider  43  from a small-diameter gear of the double gear  70  meshing with the rack gear  43   a , whereby the loading slider  43  moves forward or backward.  
         [0110]     The following description is now provided about operation modes of the disk unit  1  of the present invention constructed as above. As described above, the disk unit  1  of the present invention is constructed so as to permit conveyance of the large- and small-diameter disks D 1 , D 2 . First, a conveyance mode of the large-diameter disk D 1  will be described with reference to FIGS.  9  to  22  and a conveyance mode of the small-diameter disk D 2  will be described with reference to FIGS.  23  to  36 .  
         [0111]     FIGS.  9  to  15  are plan views illustrating, with solid lines, main constituent portions exposed to the surface of the base panel  6  and illustrating, with broken lines, main constituent portions on the back side of the base panel  6 . FIGS.  16  to  22  are bottom views illustrating, with solid lines, main constituent portions exposed to the back side of the base panel  6  and illustrating, with broken lines, main constituent portions on the surface side of the base panel  6 . Properly speaking, the cam grooves  43   e ,  48   c  and the driven pins  7   a ,  7   b  do not appear in FIGS.  9  to  15 , but for the convenience of explanation and for easier understanding, they are illustrated in those figures.  
         [0112]      FIGS. 9 and 16  show a state in which the disk unit is waiting for insertion of the large-diameter disk D 1  from the slot  3   a  of the bezel  3  and the arms stand sill in an initial condition. At this time, the large-diameter portion  64   a  of the roller  64  of the roller supporting plate  62  which is fixed to the pivot pin  26  on the back side of the base panel  6  is in abutment against the lower guide piece  65   b  of the rack slider  65  as shown in  FIGS. 8 and 16  and the guide arm  25  is at rest in a position pivoted in the centrifugal direction by a predetermined amount from a position most pivoted in the centripetal direction.  
         [0113]     This is for the following reason. If there is adopted a construction wherein the guide arm  25  stops at the position most pivoted in the centripetal direction and waits for insertion of a disk, when the small-diameter disk D 2  is inserted into the disk unit in proximity to the left side of the disk unit, the small-diameter disk D 2  enters the left side of the support member  25   a  and it becomes impossible to convey the small-diameter disk D 2 . For preventing the occurrence of such an inconvenience, the guide arm  25  is stopped at a position pivoted in the centrifugal direction by a predetermined amount from the position most pivoted in the centripetal direction and is allowed to wait for insertion of the disk.  
         [0114]     Since the base end portion of the guide arm  27  is urged by the extension spring  53 , a force acting to pivot the tip support member  27   a  in the centripetal direction is exerted constantly on the guide arm  27 . However, since the third pivotable member  51  connected to the pivot pin  27   b  stands still at its predetermined position, the guide arm  27  is at rest in its states shown in  FIG. 9 . This is because the link wire  52  stretched between the first pivotable member  45  which is at a standstill and the work pin  51   a  of the third pivotable member  51  functions as a stopper and inhibits a pivotal movement of the third pivotable member  51 .  
         [0115]     Likewise, the disk supporting arm  19 , the guide arms  29 ,  35  and the loading arm  22 , to which power is transmitted with movement of the loading slider  43 , are also at rest in the respective states shown in  FIG. 9 . Further, the driven pin  7   a  of the lift frame  7  which is guided by the cam groove  43   e  of the loading slider  43  lies in the lower portion  43   e - 1  of the cam groove  43   e , while the driven pin  7   b  of the lift frame  7  which is guided by the cam groove  48   c  of the driven slider  48  lies in the lower portion  48   c - 1  of the cam groove  48   c , so that the lift frame  7  assumes its most descended state as shown in  FIG. 37 (A).  
         [0116]      FIGS. 10 and 17  show a state in which the large-diameter disk D 1  is inserted from the slot  3   a  of the bezel  3  by an operator and its front end side is put in abutment against both holder  21  of the disk supporting arm  19  and support member  29   a  of the guide arm  29 . At this time, the large-diameter disk D 1  pushes the support member  25   a  provided at the tip of the guide arm  25  and moves pivotally in the centrifugal direction from its position shown in phantom line in  FIG. 10 . At the same time, a side portion of the large-diameter disk D 1  pushes the retaining end portion  41   a  of the lead wire  41  and slides in the direction of arrow in the same figure. As a result, the lock lever  37  is pulled by the lead wire  41  and the angle  37   a  formed at the tip of the lock lever  37  moves pivotally in the direction of arrow in the same figure and is therefore deviated from the locking range for the tongue piece  29   b  provided at the tip of the guide arm  29 .  
         [0117]      FIGS. 11 and 18  show a further inserted state of the large-diameter disk D 1  from the above condition by the operator. The disk supporting arm  19  and the guide arms  25 ,  29  are pushed by the large-diameter disk D 1  and move pivotally in the centrifugal direction. Consequently, a base portion of the disk supporting arm  19  rotates from its position shown in  FIG. 39 (A) up to its position shown in  FIG. 39 (B) with the rivet pin  20  as a fulcrum and the limit switch  60  is actuated by the switch starting stepped portion  59   e  of the gear disc  59 . At this time, the rack slider  65  meshing with the gear disc  59  advances slightly.  
         [0118]     An electric current of a low voltage flows in the loading motor  66  at this time point in accordance with a signal provided from the limit switch  60  which has been actuated by the switch starting stepped portion  59   e . As a result, the loading slider  43  retreats and pulls the link lever  24 , the loading arm  22  moves pivotally up to its position shown in phantom line in  FIG. 18  and the loading roller  22   a  provided at the tip of the loading arm  22  comes into abutment against a side portion of the large-diameter disk D 1  and stops.  
         [0119]     The foregoing electric current of a low voltage is set on the basis of a potential necessary for the conveyance of the small-diameter disk D 2  which will be described later. If an electric current of a high potential for generating a large torque necessary for the loading of the large-diameter disk D 1  is flowed at this stage, there is a fear that there may occur a malfunction in the conveyance mechanism. More particularly, in  FIG. 11 , since a component of force F 1   a  induced by pressing of the loading roller  22   a  and a component of force F 1   b  induced by pressing of the support member  25   a  of the guide arm  25  lie near the center of the large-diameter disk D 1 , a resultant force thereof is extremely small and thus a force acting to propel the large-diameter disk D 1  in the loading direction is not generated. Besides, in the state shown in  FIG. 11 , the support member  29   a  provided at the tip of the guide arm  29  and being urged in the centripetal direction is pushing a rear side portion of the large-diameter disk D 1 .  
         [0120]     In this condition, if an electric current of a high potential necessary for the conveyance of the large-diameter disk D 1  is fed to the loading motor  66 , the loading arm  22  stops while gripping the large-diameter disk D 1  and the loading operation comes to a stop. Continuance of this state leads to a likelihood of risk such as breakage of the gear train in the conveyance mechanism or burnout of the loading motor  66 . At this stage, for avoiding the occurrence of such an inconvenience, an electric current of a low voltage necessary for the conveyance of the small-diameter disk D 2  is fed to the loading motor  66 .  
         [0121]     With only the driving force of the loading motor  66  in the above condition with a low voltage current flowing in the loading motor  66 , the large-diameter disk D 1  acts as a load and the loading arm  22  fails to turn, so that an operation for conveyance of the large-diameter disk D 1  is not performed. When the operator pushes the large-diameter disk D 1 , the driving force of the loading motor  66  and the pushing force of the operator acting in the disk inserting direction are applied to the disk and there is performed an operation for conveyance of the large-diameter disk D 1 .  
         [0122]      FIGS. 12 and 19  show a further inserted state of the large-diameter disk D 1  from the above condition by the operator. The gear disc  59  provided at the base portion of the disk supporting arm  19  further rotates, whereby the link arm  54  is pulled, the first pivotable member  45  moves pivotally about the rivet pin  44  and the driven pin  45   a  moves backward. Consequently, the loading slider  43  which is in an urged state with the driving force of the loading motor  66  with a low voltage current flowing therein also moves backward.  
         [0123]     With these operations, the guide arm  29  moves pivotally in the centrifugal direction and the supported state of the large-diameter disk D 1  by the support member  29   a  is released. This results from a condition such that the driven pin  29   d  of the guide arm  29  positioned on the slant face of the rear end portion of the guide groove  43   c - 1  in the loading slider  43  undergoes the action of the said slant face with retreat of the loading slider  43  in the state of  FIG. 11 .  
         [0124]     With the foregoing pivotal movement of the first pivotable member  45 , the third pivotable member  51  whose pivotal movement is inhibited by the link wire  52  moves pivotally about the rivet pin  50  under the action of the extension spring  53 . As a result, the guide arm  27  moves pivotally in the centripetal direction and a rear side portion of the large-diameter disk D 1  is supported by the support member  27   a  provided at the tip of the guide arm  27 . At this time, the link lever  24  is pulled with retreat of the loading slider  43 , so that the loading arm  22  moves pivotally in the centripetal direction and the loading roller  22   a  provided at the tip of the loading arm  22  comes into abutment against and supports a front side portion of the large-diameter disk D 1 . The driven pin  7   a  of the lift frame  7  is in a state of laterally moving through the lower portion  43   e - 1  of the cam groove  43   e  and therefore the lift frame  7  stops at its position shown in  FIG. 37 (A).  
         [0125]     On the other hand, the gear disc  59  provided at the base portion of the disk supporting arm  19  rotates up to its position shown in  FIG. 39 (C) and the switch starting stepped portion  59   f  inverts the switch knob  60   a  of the limit switch  60 . The electric current flowing in the loading motor  66  is switched to a high potential current in accordance with a signal provided at this instant from the limit switch  60  to generate a torque necessary for loading of the large-diameter disk D 1 . Further, since the component of force F 1   a  induced by pressing of the loading roller  22   a  and the component of force F 1   b  induced by pressing of the support member  25   a  of the guide arm  25  become large, there is generated a resultant force F 2  acting to propel the disk in the loading direction and an automatic loading by the loading motor  66  is started.  
         [0126]      FIGS. 13 and 20  show a state in which the automatic loading by the loading motor  66  is started and the large-diameter disk D 1  is being loaded. When the loading slider  43  further retreats from the state of  FIG. 12 , the driven pin  29   d  of the guide arm  29  enters the guide groove  43   c - 1  from the slant portion of the loading slider  43 . As a result, the guide arm  29  further pivots in the centrifugal direction and the support member  29   a  provided at the tip of the guide arm  29  assumes a state free of contact with a side portion of the large-diameter disk D 1 . FIGS.  40 (A) to  40 (D) show operation modes of the guide arm  29  in a continuous manner.  
         [0127]     As the loading slider  43  moves backward, the link lever  24  is pulled to start a pivotal movement in the centripetal direction of the loading arm  22 . FIGS.  41 (A) to  41 (D) show pivoting states of the loading arm  22  in a continuous manner. The state of the loading arm  22  shown in  FIG. 12  corresponds to a shifted state to  FIG. 41 (B) from an initial state of  FIG. 41 (A).  
         [0128]     As noted earlier, the driven pin  24   a  fixed to the tip of the link lever  24  which causes a pivotal movement of the loading arm  22  is inserted into both guide groove  43   d  of the loading slider  43  and the guide slit  49   a  of the guide plate  49 , so upon retreat of the loading slider  43 , the driven pin  24   a  is held grippingly between the rear-end slant face of the guide groove  43   d  and a side wall of the guide slit  49   a  and therefore retreats as well. Consequently, the link lever  24  is pulled and the loading arm  22  moves pivotally.  
         [0129]     When the loading slider  43  retreats up to its position shown in  FIG. 13 , the upper-end horizontal portion  43   b - 1  of the guide groove  43   b  pushes up the driven pin  45   a  of the first pivotable member  45 , causing the first pivotable member  45  to move pivotally about the rivet pin  44  and causing rotation of the gear disc  59  through the link arm  54 . As a result, the disk supporting arm  19  moves pivotally in the centrifugal direction, that is, the holder  21  which supports the rear end portion of the large-diameter disk D 1  moves backward in synchronism with the loading of the large-diameter disk D 1 . At this-stage, the driven pin  47   a  of the second pivotable member  47  is sliding along the vertical portion of the guide groove  43   b , so that the second pivotable member  47  is at a standstill and so is the driven slider  48 .  
         [0130]     With the loading of the large-diameter disk D 1 , the support member  27   a  provided at the tip of the guide arm  27  which is urged by the extension spring  53  in the course of shift from the state of  FIG. 12  to the state of  FIG. 13  is pushed back as in  FIG. 13  into abutment against the retaining tongue piece  42   a  of the lever arm  42  and stops. At this time, the third pivotable member  51  slightly moves pivotally and therefore its work pin  51   a  moves in the centripetal direction through the end through hole  48   b  of the driven slider  48  which stands still, thus resulting in that the link wire  52  is slightly deflected.  
         [0131]     On the other hand, the support member  25   a  of the guide arm  25  supports a front side portion of the large-diameter disk D 1  and the upper guide piece  65   c  of the rack slider  65  which has advanced with rotation of the gear disc  59  is in a spaced state from the small-diameter portion  64   b  of the double roller  64 . At this time, the driven pin  7   a  of the lift frame  7  is in a state of laterally moving through the lower portion  43   e - 1  of the cam groove  43   e  and the driven slider  48  is at rest, so that the lift frame  7  still stands still at its position shown in  FIG. 37 (A).  
         [0132]      FIGS. 14 and 21  show a state in which the loading slider  43  further retreats from its state shown in  FIGS. 13 and 20 , the link lever  24  is pulled, causing the loading arm  22  to move pivotally up to its position shown in  FIG. 41 (C), and the center of the center hole D 1   a  of the large-diameter disk D 1  which has been loaded and the center of the clamp head  9  are aligned with each other. On the other hand, the driven pin  29   d  of the guide arm  29  moves straight through the guide groove  43   c - 1  of the loading slider  43 , so that the guide arms  29  and  35  are at rest in their positions shown in  FIG. 14 . At this time, the support members  29   a  and  35   a  catch and position the outer periphery edge of the large-diameter disk D 1 , whereby the center hole D 1   a  of the large-diameter disk D 1  and the clamp head  9  are accurately aligned with each other.  
         [0133]     With the retreat of the loading slider  43 , the driven pin  45   a  of the first pivotable member  45  is pushed up to the upper-end horizontal portion  43   b - 1  and shifts to the vertical portion  43   b - 3 , so that the first pivotable member  45  moves pivotally up to its position shown in the drawings, and the disk supporting arm  19  also pivots in the centrifugal direction with rotation of the gear disc  59  caused by the link arm  54 . The rotation of the gear disc  59  causes a further advance of the rack slider  65  and the small-diameter portion  64   b  of the double roller  64  strikes on the upper guide piece  65   c , so that the guide arm  25  largely pivots in the centrifugal direction and the support of the outer periphery edge of the large-diameter disk D 1  by the support member  25   a  is ended. Now, the guide arm  25  is retracted sideways of the lift frame  7  and does not extend over the lift frame  7 . Thus, there is no fear of collision between the lift frame  7  which is rising and the guide arm  25 .  
         [0134]     At this time, the large-diameter disk D 1  presses the support member  27   a  of the guide arm  27 , but since the support member  27   a  is abutted against the retaining tongue piece  42   a  of the lever arm  42  and a stop position thereof is established, so that the center of the large-diameter disk D 1  is aligned with the clamp head  9  in the horizontal direction at this stage. On the other hand, a vertical center of the large-diameter disk D 1  relative to the clamp head  9  is established by the holder  21  of the disk supporting arm  19  which stands still in the state shown in  FIG. 14  and the loading roller  22   a  of the loading arm  22 .  
         [0135]     Thus, according to the disk unit of the present invention, from the time the automatic loading of the large-diameter disk D 1  is started until reaching the state of  FIG. 14 , the large-diameter disk D 1  is supported in at least three positions of its outer periphery edge by the foregoing plural arms and is stopped in the position where the disk as loaded into the disk unit can be clamped in its center hole D 1   a  by the clamp head  9 .  
         [0136]     In the course of shift from  FIG. 13  to  FIG. 14 , the driven pin  7   a  of the lift frame  7  shifts from the lower portion  43   e - 1  to the slant portion  43   e - 2  and rises with retreat of the cam groove  43   e  of the loading slider  43 . On the other hand, the driven pin  47   a  of the second pivotable member  47  passes the vertical portion  43   b - 3  of the loading slider  43  and reaches the lower-end horizontal portion  43   b - 2  and the second pivotable member  47  moves pivotally in the centrifugal direction, so that the work pin  47   b  causes the driven slider  48  to move horizontally, with a consequent horizontal movement of the cam groove  48   c . Accordingly, the driven pin  7   b  of the lift frame  7  shifts from the lower portion  48   c - 1  to the slant portion  48   c - 2  and rises and the lift frame  7  starts to rise as shown in  FIG. 37 (B).  
         [0137]      FIGS. 15 and 22  show a final state in which the clamp head  9  clamps the center hole D 1   a  of the large-diameter disk D 1 , thereby permitting drive of the large-diameter disk D 1 . For reaching this state it is necessary that the loading arm  22  and the guide arm  27  pivot slightly in the centrifugal direction to terminate the support of the large-diameter disk D 1  so as not to be an obstacle to rotation of the disk.  
         [0138]     More particularly, at a further retreated and stopped position of the loading slider  43  from the state of  FIG. 14 , the driven pin  24   a  of the link lever  24  is pushed into a lateral groove in a rear end of the guide slit  49   a  at a vertical offset portion of the rear portion of the guide groove  43   d , so that, as shown in  FIG. 41 (D), the link lever  24  returns slightly in the direction opposite to the pulling direction and the loading arm  22  pivots slightly in the centrifugal direction to terminate the support of the outer periphery edge of the large-diameter disk D 1  by the loading roller  22   a.    
         [0139]     At the same time, the driven pin  45   a  of the first pivotable member  45  is slightly pivoted by a slant portion formed at a middle position of the vertical portion  43   b - 3  of the guide groove  43   b  and this pivotal motion is transmitted to the gear disc  59  through the link arm  54 . As a result, the disk supporting arm  19  pivots slightly in the centrifugal direction to terminate the support of the outer periphery edge of the large-diameter disk D 1  by the disk supporting arm  19 .  
         [0140]     On the other hand, the driven pin  47   a  of the second pivotable member  47  is pushed up largely in the lower-end horizontal portion  43   b - 2  of the guide groove  43   b  in the loading slider  43 , whereby the work pin  47   b  pivots in the centrifugal direction, causing the driven slider  48  to move horizontally, and the end through hole  48   b  pulls the work pin  51   a  of the third pivotable member  51 . As a result, the third pivotable member  51  pivots slightly and at the same time the work piece  48   d  pushes up the roller  42   c  of the lever arm  42 , whereby the retaining tongue piece  42   a  of the lever arm  42  against which the support member  27   a  of the guide arm  27  is abutted moves backward. Consequently, the guide arm  27  pivots slightly in the centrifugal direction to terminate the support of the outer periphery edge of the large-diameter disk D 1  by the guide arm  27 .  
         [0141]     At this time, an end portion of the guide groove  43   c - 1  of the loading slider  43  pushes the driven pin  29   d  of the guide arm  29 , whereby the guide arm  29  pivots slightly. As a result, the support member  29   a  of the guide arm  29  pivots in the centrifugal direction to complete positioning of the outer periphery edge of the large-diameter disk D 1 . Further, the guide arm  35  connected through the driven pin  35   b  to the guide groove  29   c  of the guide arm  29  pivots slightly, whereby the support member  35   a  also pivots in the centrifugal direction to complete positioning of the outer periphery edge of the large-diameter disk D 1 .  
         [0142]     In the course of shift from  FIG. 14  to  FIG. 15 , the driven slider  48  moves horizontally in synchronism with retreat of the loading slider  43 , but the driven pin  7   a  of the lift frame  7  shifts from the slant portion  43   e - 2  of the cam groove  43   e  in the loading slider  43  to the higher portion  43   e - 3  and the driven pin  7   b  shifts from the slant portion  48   c - 2  of the cam groove  48   c  in the driven slider  48  to the higher portion  48   c - 3 .  
         [0143]     In this process the lift frame  7  behaves as follows. The lift frame  7  rises by the driven pins  7   a  and  7   b  which rise along the slant portions  43   e - 2  and  48   c - 2 , the chucking pawl  9   a  of the clamp head  9  comes into abutment against the center hole D 1   a  of the large-diameter disk D 1  and pushes up the large-diameter disk D 1 , as shown in  FIG. 37 (C), and the peripheral edge of the center hole D 1   a  comes into abutment against the protuberance  2   b  of the chassis case  2 .  
         [0144]     When the driven pins  7   a  and  7   b  reach the tops of the slant portions  43   e - 2  and  48   c - 2  from the above state, the clamp head  9  is fitted in the center hole D 1   a  of the large-diameter disk D 1  to complete clamping by the chucking pawl  9   a , as shown in  FIG. 37 (D), whereby the large-diameter disk D 1  is fixed onto the turntable  10 . Then, the driven pins  7   a  and  7   b  shift to the higher portions  43   e - 3  and  48   c - 3 , whereby the lift frame  7  descends to its position shown in  FIG. 37 (E), thus permitting drive of the large-diameter disk D 1 .  
         [0145]     Operation modes of various mechanisms during loading of the large-diameter disk D 1  by the disk unit  1  of the present invention have been described above, but, during unloading, the mechanisms operate in accordance with a sequence reverse to the above loading sequence with advance of the loading slider  43 . That is, when unloading of the large-diameter disk D 1  is started and the loading slider  43  starts to advance, the lift frame  7  once rises and then descends to its initial position, as shown in FIGS.  38 (A) to  38 (E). In the meantime, the large-diameter disk D 1  is stuck up by a clamp release pin  71  as shown in  FIG. 38 (C), whereby the clamped state by the clamp head  9  is released.  
         [0146]     In the above process up to release of the clamp of the large-diameter disk D 1 , the disk supporting arm  19 , loading arm  22  and guide arm  27  start moving pivotally in the centripetal direction to support the outer periphery edge of the large-diameter disk D 1  as shown in  FIG. 14 . Subsequently, the large-diameter disk D 1  is unloaded with the pivoting force in the centripetal direction of the disk supporting arm  19  and is stopped in a state in which its front end portion is exposed from the slot  3   a  of the bezel  3 .  
         [0147]     Operation modes of the driven pins  24   a ,  29   d ,  45   a  and  47   a  with retreat of the loading slider  43  are shown in a continuous manner in FIGS.  42 (A) to  42 (F).  
         [0148]     Next, operation modes in case of conveying the small-diameter disk D 2  by the disk unit of the present invention will be described with reference to plan views of FIGS.  23  to  29  and bottom views of FIGS.  30  to  36 . Properly speaking, the cam grooves  43   e ,  48   c  and the driven pins  7   a ,  7   b  do not appear in FIGS.  23  to  29 , but they are illustrated therein for the convenience of explanation and for easier understanding.  
         [0149]      FIGS. 23 and 30  show a state in which the disk unit is waiting for insertion therein of the small-diameter disk D 2  from the slot  3   a  of the bezel  3 , with the arms being at rest in their initial states. At this time, the large-diameter portion  64   a  of the roller  64  of the roller supporting plate  62  fixed to the pivot pin  26  on the back side of the base panel  6  is in abutment against the lower guide piece  65   b  of the rack slider  65  as shown in  FIGS. 8 and 30  and the guide arm  25  is at rest in a position pivoted in the centrifugal direction by a predetermined amount from the position most pivoted in the centripetal direction.  
         [0150]     This is for the following reason. According to a construction wherein the guide arm  25  stops at the most pivoted position in the central direction and waits for insertion of the disk, when the small-diameter disk D 2  is inserted near the left side of the disk unit, the small-diameter disk D 2  enters the left side of the support member  25   a , making the conveyance of the small-diameter disk D 2  impossible. To prevent the occurrence of this inconvenience, the guide arm  25  is stopped at a position pivoted in the centrifugal direction by a predetermined amount from the most pivoted position in the centripetal direction and is allowed to wait for insertion of the disk. The state of waiting for insertion of the small-diameter disk D 2  shown in  FIGS. 23 and 30  is coincident with the state of waiting for insertion of the large-diameter disk D 1  shown in  FIGS. 9 and 16 .  
         [0151]     Since the base end portion of the guide arm  27  is urged by the extension spring  53 , a force acting to pivot the tip support member  27   a  in the centripetal direction is always exerted on the guide arm  27 , but the third pivotable member  51  connected to the pivot pin  27   b  is at rest in its predetermined position and the guide arm  27  stands still in its state shown in  FIG. 23 . This is because the link wire  52  stretched between the first pivotable member  45  which is at a standstill and the work pin  51   a  of the third pivotable member  51  functions as a stopper to inhibit a pivotal motion of the third pivotable member  51 .  
         [0152]     Likewise, the disk supporting arm  19 , the guide arms  29 ,  35  and the loading arm  22  are also at rest in their states shown in  FIG. 23 . The driven pin  7   a  of the lift frame  7  which is guided by the cam groove  43   e  of the loading slider  43  lies in the lower portion  43   e - 1  of the cam groove  43   e , while the driven pin  7   b  of the lift frame  7  which is guided by the cam groove  48   c  of the driven slider  48  lies in the lower portion  48   c - 1  of the cam groove  48   c , so that the lift frame  7  is in its most descended state as shown in  FIG. 37 (A).  
         [0153]      FIGS. 24 and 31  show a state in which the small-diameter disk D 2  is inserted from the slot  3   a  of the bezel  3  by the operator and the front end side of the small-diameter disk D 2  is abutted against the holder  21  of the disk supporting arm  19 . In the insertion of the small-diameter disk D 2  into the slot  3   a  at this stage, if the small-diameter disk D 2  is offset to the left in  FIG. 24 , the left side portion of the front end of the small-diameter disk D 2  contacts the support member  25   a  of the guide arm  25  and is pushed back, whereby it is possible to prevent dislodgment of the small-diameter disk D 2  from the conveyance path.  
         [0154]     In the inserting operation of the small-diameter disk D 2 , if the right side portion of the front end of the small-diameter disk D 2  presses the support member  29   a  of the guide arm  29  and causes the support member to pivot in the centrifugal direction as shown in  FIG. 43 (A), the tongue piece  29   b  is locked by the angle  37   a  of the lock lever  37  which is at rest in its predetermined position without pivoting as in  FIG. 43 (B). Therefore, also in this case it is possible to prevent dislodgment of the small-diameter disk D 2  from the conveyance path. That is, the small-diameter disk D 2  is guided to the center of the disk unit by both support member  25   a  of the guide arm  25  and support member  29   a  of the guide arm  29 .  
         [0155]      FIGS. 25 and 32  show a further inserted state of the small-diameter disk D 2  from the above condition by the operator. The disk supporting arm  19  is pressed by the small-diameter disk D 2  and pivots in the centrifugal direction, further, the support member  25   a  of the guide arm  25  which is interlocked with the pivotal movement of the disk supporting arm  19  and the support member  29   a  of the guide arm  29  come into contact with a side portion of the small-diameter disk D 2 . As a result, the small-diameter disk D 2  assumes a three-point supported state by the support members  25   a ,  29   a  and the holder  21  of the disk supporting arm  19 .  
         [0156]     The base portion of the disk supporting arm  19  rotates about the rivet pin  20  from the position shown in  FIG. 39 (A) to the position shown in  FIG. 39 (B) and the limit switch  60  is actuated by the switch starting stepped portion  59   e  of the gear disc  59 . An electric current of a low voltage flows in the loading motor  66  in accordance with a signal provided from the limit switch  60  thus actuated by the switch starting stepped portion  59   e . At this time, the component of force F 1   a  induced by pressing of the support member  29   a  of the guide arm  29  and the component of force F 1   b  induced by pressing of the support member  25   a  of the guide arm  25  under the action of the extension spring  63  are strongly exerted on the disk, so that there occurs a resultant force F 2  of propelling the small-diameter disk D 2  in the loading direction, whereby an automatic loading is started by the loading motor  66 .  
         [0157]      FIGS. 26 and 33  show a state in which the automatic loading is started by the loading motor  66  and the small-diameter disk D 2  has been loaded. When the loading slider  43  further retreats from the state shown in  FIG. 25 , the driven pin  29   d  of the guide arm  29  enters the guide groove  43   c - 2  of the loading slider  43 . At this time, the support member  29   d  is guided by the slant portion of the guide groove  43   c - 2  and moves a distance corresponding to the slant distance and the support member  29   a  pivots up to its illustrated position under loading of the small-diameter disk D 2 . At this time, under the action of the extension spring  63  the guide arm  25  also pivots to its illustrated position while the small-diameter disk D 2  is being loaded.  
         [0158]     When the loading slider  43  retreats up to its position shown in  FIG. 26 , the upper-end horizontal portion  43   b - 1  of the guide groove  43   b  pushes up the driven pin  45   a  of the first pivotable member  45 , causing the first pivotable member  45  to pivot about the rivet pin  44  and thereby causing the gear disc  59  to rotate through the link arm  54 . As a result, the disk supporting arm  19  pivots in the centrifugal direction, that is, the holder  21  which supports the rear end portion of the small-diameter disk D 2  retreats in synchronism with loading of the small-diameter disk D 2 . At this stage, the driven pin  47   a  of the second pivotable member  47  is sliding along the vertical portion of the guide groove  43   b , so that the second pivotable member  47  stands still and so does the driven slider  48 .  
         [0159]     Thus, with the pivotal movement of the first pivotable member  45 , the third pivotable arm  51  also pivots under the action of the extension spring  53 , so that the guide arm  27  pivots about the rivet pin  28  and its support member  27   a  comes into abutment against the small-diameter disk D 2 . At this time, the driven pin  7   a  of the lift frame  7  is moving laterally through the lower portion  43   e - 1  of the cam groove  43   e  and the driven slider  48  is at rest, so that the lift frame  7  remains in its position shown in  FIG. 37 (A).  
         [0160]      FIGS. 27 and 34  show a state in which the loading slider  43  further retreats from its state shown in  FIGS. 26 and 33  and the loading of the small-diameter disk D 2  is continued. The guide arm  29  does not pivot, but in accordance with the amount of movement of the loading slider  43  the disk supporting arm  19  pivots in the centrifugal direction and the guide arms  25  and  27  pivot in the centripetal direction to support the small-diameter disk D 2 .  
         [0161]      FIGS. 28 and 35  show a state in which the loading slider  43  further retreats from its state shown in  FIGS. 27 and 34  and the center of the center hole D 2   a  of the small-diameter disk D 2  and that of the clamp head  9  are aligned with each other, bringing the disk to a stop. In the process up to such a state, as the loading slider  43  retreats, the disk supporting arm  19  pivots largely in the centrifugal direction to terminate the support of the outer periphery edge of the small-diameter disk D 2  and as a result of this pivotal movement the gear disc  59  causes the rack slider  65  to move forward. Consequently, the small-diameter portion  64   a  of the double roller  64  strikes on the upper guide piece  65   c  of the rack slider  65  and hence the guide arm  25  pivots largely in the centrifugal direction to terminate the support of the outer periphery edge of the small-diameter disk D 2 . Now, the guide arm  25  is retracted sideways of the lift frame  7  and does not extend onto the lift frame  7 .  
         [0162]     In the above condition, the outer periphery edge of the small-diameter disk D 2  is three-point supported by the support member  27   a  of the guide arm  27 , the support member  29   a  of the guide arm  29  and the support member  35   a  of the guide arm  35 . In the process up to this state the pressing force of the support member  27   a  of the guide arm  27  based on the action of the extension spring  53  is exerted on the small-diameter disk D 2 , whereby the loading of the disk D 2  is continued.  
         [0163]     In the process from  FIG. 27  to  FIG. 28 , as the cam groove  43   e  of the loading slider  43  retreats, the driven pin  7   a  of the lift frame  7  shifts from the lower portion  43   e - 1  to the slant portion  43   e - 2  and assumes to rising state. On the other hand, the driven pin  47   a  of the second pivotable member  47  passes the vertical portion  43   b - 3  of the loading slider  43  and reaches the lower-end horizontal portion  43   b - 2 , causing the second pivotable member  47  to pivot in the centrifugal direction, so that the work pin  47   b  causes the driven slider  48  to move horizontally and at the same time the cam groove  48   c  moves horizontally. As a result, the driven pin  7   b  of the lift frame  7  shifts from the lower portion  48   c - 1  to the slant portion  48   c - 2  and assumes a rising state and the lift frame  7  starts to rise as shown in  FIG. 37 (B).  
         [0164]      FIGS. 29 and 35  show a final state in which the clamp head  9  clamps the center hole D 2   a  of the small-diameter disk D 2 , permitting drive of the small-diameter disk D 2 . For achieving this state it is necessary that the guide arms  27 ,  29  and  35  pivot and terminate the support of the small-diameter disk D 2  so as not to be an obstacle to rotation of the small-diameter disk D 2 .  
         [0165]     That is, in the further retreated and stopped position of the loading slider  43  from the state of  FIG. 28 , the driven pin  47   a  is pushed up by the lower-end horizontal portion  43   b - 2  and the second pivotable member  47  pivots in the centrifugal direction. As a result, the work pin  51   a  connected to the end through hole  48   b  of the driven slider  48  is pulled and the third pivotable member  51  pivots in the centripetal direction, whereby the guide arm  27  is pivotally moved in the centrifugal direction to terminate the support of the small-diameter disk D 2 .  
         [0166]     On the other hand, the driven pin  29   d  of the guide arm  29  reaches the slant portion at the terminal end of the guide groove  43   c - 2  in the loading slider  43  and therefore the guide arm  29  pivots slightly in the centrifugal direction, so that the support of the small-diameter disk D 2  by the support member  29   a  is ended. With this pivotal movement of the guide arm  29 , the driven pin  35   b  connected to the guide groove  29   c  of the guide arm  29  is operated to pivot the guide arm  35  slightly in the centrifugal direction, thereby terminating the support of the small-diameter disk D 2 .  
         [0167]     In the process from  FIG. 28  to  FIG. 29 , the driven slider  48  moves horizontally in synchronism with retreat of the loading slider  43 , but the driven pin  7   a  of the lift frame  7  shift from the slant portion  43   e - 2  of the cam groove  43   e  in the loading slider  43  to the higher portion  43   e - 3  and the driven pin  7   b  shifts from the slant portion  48   c - 2  of the cam groove  48   c  in the driven slider  48  to the higher portion  48   c - 3 .  
         [0168]     In this process the lift frame  7  behaves as follows. The lift frame  7  rises by the driven pins  7   a  and  7   b  which rise by the slant portions  43   e - 2  and  48   c - 2 , then, as shown in  FIG. 37 (C), the chucking pawl  9   a  of the clamp head  9  comes into abutment against the center hole D 2   a  of the small-diameter disk D 2  and pushes up the small-diameter disk D 2 , so that the peripheral edge of the center hole D 2   a  comes into abutment against the protuberance  2   b  of the chassis case  2 .  
         [0169]     When the driven pins  7   a  and  7   b  reach the tops of the slant portions  43   e - 2  and  48   c - 2  from the above condition, as shown in  FIG. 37 (D), the clamp head  9  is fitted in the center hole D 2   a  of the small-diameter disk D 2  to complete clamping by the chucking pawl  9   a  and the small-diameter disk D 2  is fixed thereby onto the turntable  10 . As the driven pins  7   a  and  7   b  shift to the higher portions  43   e - 3  and  48   c - 3 , the lift frame  7  descends to its position shown in  FIG. 37 (E), thus permitting drive of the small-diameter disk D 2 .  
         [0170]     Operation modes of various mechanisms during loading of the small-diameter disk D 2  by the disk unit  1  of the present invention has been described above, but for unloading of the disk the mechanisms operate with advance of the loading slider  43  in accordance with a sequence reverse to the above loading sequence. That is, when the unloading of the small-diameter disk D 2  is started and the loading slider  43  starts to advance, the lift frame  7  once rises and then descends to its initial position, as shown in FIGS.  38 (A) to  38 (E). In the meantime, the small-diameter disk D 2  is stuck up by the clamp release pin  71  as shown in  FIG. 38 (C), whereby the clamped condition by the clamp head  9  is released.  
         [0171]     In the process up to unclamping of the small-diameter disk D 2  performed in the above manner, the guide arms  25 ,  27  and  29  pivot in the centripetal direction and assume the state shown in  FIG. 28  in which they support the outer periphery edge of the small-diameter disk D 2 . Subsequently, operations are performed in a sequence reverse to the above sequence, like FIGS.  27  to  24 , during which the small-diameter disk D 2  is unloaded with the pivoting force in the centripetal direction of the disk supporting arm  19  until the front end portion thereof is exposed from the slot  3   a  of the bezel  3  and then stops.  
         [0172]     Next, a construction for avoiding damage of the optical pickup  12  in the disk unit  1  constructed as above will be described with reference to FIGS.  44  to  48 .  FIG. 44  is a plan view showing on a larger scale the pivoting portion of the guide arm  25  in the above-described construction. The guide arm  25  indicated with a solid line in the same figure is in a state of waiting for insertion of the large- and small-diameter disks D 1 , D 2  from the slot  3   a  of the bezel  3 .  
         [0173]     At this time, the optical pickup  12  adapted to reciprocate within the lift frame  7  is at rest in a position close to the bezel  3  which is remotest in the centrifugal direction from the turntable  10 . This is for the following reason. The wall thickness of the optical pickup  12  is large, so if the optical pickup  12  is allowed to stop at the position closest to the turntable  10 , its bottom comes into abutment against the bottom plate of the chassis case  2  with a large descent of the end portion of the lift frame  7  close to the turntable  10  because the lift frame  7  uses the bezel  3  side as a fulcrum of its pivotal motion.  
         [0174]     Such an inconvenience can be avoided by making large the gap between the back side of the aforesaid end portion of the lift frame  7  and the bottom plate of the chassis case  2 , but an increase in wall thickness of the entire disk unit results and thus it becomes impossible to meet the demand for the reduction of thickness. In view of this point, in the initial state in which the end portion in question of the lift frame  7  is most descended, the optical pickup  12  is approximated to the pivotal fulcrum where the amount of pivotal descent of the lift frame  7  is the smallest and is allowed to stand still there, thereby making the reduction of thickness possible.  
         [0175]     Therefore, in a state in which the optical pickup  12  is at rest as shown in  FIG. 44 , particularly an objective lens  12   b  thereof is positioned under a pivoting path L 1  of the support member  25   a  of the guide arm  25 . Thus, there remains the possibility of occurrence of a problem in the conveyance process of the small-diameter disk D 2  shown in FIGS.  25  to  26 .  
         [0176]     That is, when the guide arm  25  starts conveyance of the small-diameter disk D 2  and the support member  25   a  moves pivotally in the centripetal direction, there is created a state in which a free end of the support member  25   a  confronts the objective lens  12   b  of the optical pickup  12 , as shown in  FIG. 45 (A). As shown in the same figure, the confronting distance between the free end of the support member  25   a  and the objective lens  12   b  is extremely short, thus giving rise to a fear of mutual contact.  
         [0177]     However, since the guide arm  25  is in a cantilevered state with its base end portion serving as a pivotal fulcrum, even a slight vibration or shock causes the end support member  25   a  to move vertically to a large extent and strike the objective lens  12   b  as shown in  FIG. 45 (B). Moreover, the pivoting path L 1  of the support member  25   a  also overlaps a lens holder  12   a , so if the lens holder  12   a  is struck by the support member  25   a , a suspension wire  12   c  which supports the lens holder  12   a  may be deformed.  
         [0178]      FIG. 46  shows a construction adopted in the present invention for solving such a problem. In this construction, a descent inhibiting member  25   b  for the guide arm  25  is provided at the tip of the guide arm  25 . In the illustrated example, a pin member is used as the descent inhibiting member  25   b  and is fixed to the rear portion of the disk support member  25   a  by suitable means such as caulking. The descent inhibiting member  25   b  and the support member  25   a  may be integrally formed using a resin material for example, as shown in  FIG. 48 (B), and may be locked or bonded to the tip of the guide arm  25  in such a state as shown in  FIG. 48 (A).  
         [0179]     According to such a construction, when the guide arm  25  is pivoted, a pivoting path L 2  of the descent inhibiting member  25   b  assumes a shifting state from above the lift frame  7  to the carrier block  13 , so even if the tip of the guide arm  25  descends with a vertical movement of the guide arm caused by vibration or shock in the state of  FIG. 47 (A) which falls under the pivotal range of the guide arm  25 , the descent inhibiting member  25   b  comes into abutment against the lift frame  7  or the carrier block  13  to inhibit the descent of the tip of the guide arm  25 , as shown in  FIG. 47 (B), whereby the support member  25   a  can be prevented from contacting the objective lens  12   b  or the lens holder  12   a.    
         [0180]     Thus, the slot-in type disk unit  1  according to the present invention is constructed such that the outer periphery edges of the large- and small-diameter disks D 1 , D 2  can be supported by plural arms which are actuated in synchronism with advance or retreat of the loading slider  43 . Therefore, in the loading method involving a pivotal movement of arms, it became possible for the first time to effect automatic loading of disks different in diameter. Further, according to the present invention, the tip of the arm adapted to move pivotally over the optical pickup which writes or reads information to or from a disk, thereby conveying the disk, is prevented from damaging the optical pickup, whereby it is possible to improve the mechanical reliability of the disk unit.  
         [0181]     While illustrative embodiments have been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.