a preferred embodiment of the present invention will now be explained with reference to the drawings . it will be apparent to those skilled in the art from these disclosures that the following descriptions of the preferred embodiment of the present invention is provided for illustration only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents . as shown in fig1 , a disk device has a loader ( e . g ., dvd loader ) and a cabinet . the loader optically processes a disk ( e . g ., recording medium ). the loader has a panel attachment structure a and a disk tray 5 . the disk tray 5 moves the disk in and out with respect to a disk processing position for optical processing . the loader is housed in the cabinet . the cabinet is formed in a box shape that is wider in a width direction w than in a height direction h . the cabinet has a front panel 1 , a bottom chassis ( not shown ) and a top case ( not shown ) that form the box shape . the front panel 1 has an opening 21 . the disk tray 5 is movable through the opening 21 of the cabinet between an ejected position ( e . g ., open position ) outside of the cabinet and a retracted position ( e . g ., closed position ) inside of the cabinet . specifically , the disk tray 5 is movable outward ( as indicated by the arrow y 1 ) and inward ( as indicated by the arrow y 2 ) through the opening 21 of the front panel 1 . the disk is placed on , or removed from the disk tray 5 when the disk tray 5 has moved outside of the opening 21 as indicated by the arrow y 1 and has reached the ejected position . after the disk has been placed on the disk tray 5 , the disk tray 5 moves back through the opening 21 in the direction of the arrow y 2 . then , the disk is conveyed to the disk processing position . the opening 21 is formed in a bottom portion 22 of a recess 2 formed on the front panel 1 . more specifically , the opening 21 is formed in a rectangular shape that is longer in the width direction w than in the height direction h . the bottom portion 22 of the recess 2 has a rectangular ring shape . the opening 21 is bounded by the bottom portion 22 of the recess 2 . the recess 2 , the bottom portion 22 and the opening 21 of the front panel 1 are also depicted in fig1 to 13 . as shown in fig2 , the panel attachment structure a has a pair of spring bodies 3 , a decoration panel 6 and an attachment frame 8 . the decoration panel 6 is longer in the width direction w than in the height direction h . the decoration panel 6 is attached to the disk tray 5 so as to cover a front end portion of the disk tray 5 . when the disk tray 5 is moved back inside of the opening 21 as indicated by the arrow y 2 and the disk is conveyed to the disk processing position , the decoration panel 6 fits into the recess 2 and cover the opening 21 from outside . the decoration panel 6 fits into the recess 2 and hides the opening 21 , which enhances the appearance of the cabinet . the decoration panel 6 is not formed integrally with the disk tray 5 . the decoration panel 6 is instead attached as a separate member to the front end portion of the disk tray 5 . the size of the decoration panel 6 is set such that the decoration panel 6 fits into the recess 2 , but does not pass through the opening 21 . the decoration panel 6 is too large to pass through the opening 21 . thus , if the decoration panel 6 is attached to the disk tray 5 before the loader with the disk tray 5 is mounted in the cabinet , it will be impossible to take the decoration panel 6 outside of the recess 2 . therefore , the decoration panel 6 is installed to the front end portion of the disk tray 5 sticking outside of the opening 21 after the loader is mounted in the cabinet . as shown in fig2 , the decoration panel 6 has a panel main body 61 , a front decorative panel 62 . the panel main body 61 is a plastic molding that is wider in the width direction w than in the height direction h . the front decorative panel 62 is made of aluminum . the panel main body 61 and the front decorative panel 62 are integrally joined with a double - sided adhesive tape 63 . as shown in fig3 a and 3b , the attachment frame 8 is formed as a separate member that is separated from the decoration panel 6 . the attachment frame 8 is fixedly attached to the front end portion of the disk tray 5 . the attachment frame 8 has an oblong front plate 81 , a blind plate 82 and an attachment mechanism 83 . the attachment frame 8 is integrally formed as a one - piece , unitary member . the blind plate 82 extends from a upper end portion of the front plate 81 . the attachment mechanism 83 has a plurality of ribs or latching tabs . the attachment mechanism 83 immovably fixes the attachment frame 8 to the front end portion of the disk tray 5 . the spring bodies 3 link the attachment frame 8 and the decoration panel 6 . each of the spring bodies 3 includes a compression coil spring . the spring bodies 3 cause the attachment frame 8 and the decoration panel 6 to be constantly and elastically biased toward each other in backward and forward directions ( the directions indicated by the arrows y 1 and y 2 in fig1 ). the spring bodies 3 also allow displacement of the decoration panel 6 relative to the attachment frame 8 in a displacement direction that intersects with the backward and forward directions . the displacement direction includes the height direction h and the width direction w , which are perpendicular to the backward and forward directions , as well as any directions that are at some angle to the backward and forward directions . the panel attachment structure a will further be described through reference to fig3 a to 10 . as shown in fig3 a to 5b and fig7 to 10 , the decoration panel 6 has a pair of first protrusions 41 and a pair of hook components 42 . the first protrusion 41 is formed in a cylindrical shape . the first protrusion 41 is provided to the panel main body 61 . the hook component 42 is provided to the first protrusion 41 . the hook component 42 extends in an axial direction of the first protrusion 41 from a top portion of the first protrusion 41 . as shown in fig8 and 10 , each of the hook components 42 is divided into a pair of hook elements 43 . the hook elements 43 are opposite each other in a radial direction of the first protrusion 41 with a radial gap s therebetween . the hook elements 43 have shapes that are in point symmetry to each other with respect to a center axis of the first protrusion 41 . the hook elements 43 extend in the axial direction of the first protrusion 41 from the top portion of the first protrusion 41 such that the hook elements 43 maintain a positional relationship in point symmetry . each of the hook elements 43 has a catch ( e . g ., latching portion ) 44 and a lateral hole 45 . the catch 44 is formed in a hook - shape . specifically , the catch 44 opens toward the first protrusion 41 . the lateral hole 45 opens toward the radial gap s and extends toward the catch 44 . as shown in fig3 b , 4 b , 5 b and 7 , the attachment frame 8 includes a pair of first openings 84 and a pair of spring seats 85 at locations corresponding to the first protrusions 41 , respectively . the first opening 84 is formed in a circular shape . the first opening 84 is sufficiently larger in diameter than the first protrusion 41 . the first opening 84 extends through the attachment frame 8 . the first opening 84 is surrounded by the spring seat 85 . the spring seat 85 is formed in a circular shape . the first protrusion 41 is loosely fitted into the first opening 84 with a gap therebetween . the decoration panel 6 and the attachment frame 8 are aligned in a overlapping state via a positioning mechanism 7 . as shown in fig7 , the spring body 3 is fitted around the first protrusion 41 and the hook component 42 . one axial end portion of the spring body 3 is supported on the spring seat 85 of the attachment frame 8 . the spring body 3 includes a straight latching end portion ( e . g ., straight end portion ) 31 provided to the other axial end portion . the latching end portion 31 is latched by the catches 44 of the hook elements 43 . in this state , the spring body 3 is supported between the catch 44 and the spring seat 85 in a state of being compressed in the axial direction of the first protrusion 41 . therefore , the decoration panel 6 is constantly pulled toward the attachment frame 8 by the elastic biasing action of the spring bodies 3 . since the attachment frame 8 is fixed to the front end portion of the disk tray 5 , the decoration panel 6 is constantly biased by the spring body 3 toward the front end portion of the disk tray 5 . the panel attachment structure a further has the positioning mechanism 7 , a displacement width restricting mechanism 9 and a stopper mechanism 10 . the positioning mechanism 7 positions the decoration panel 6 , which is biased by the spring body 3 toward the front end portion of the disk tray 5 , in an initial position with respect to the disk tray 5 . the displacement width restricting mechanism 9 restricts displacement width of the decoration panel 6 with respect to the disk tray 5 in the displacement direction . specifically , the displacement width restricting mechanism 9 restricts displacement width of the decoration panel 6 with respect to the disk tray 5 in a direction that is perpendicular to the backward and forward directions . as shown in fig7 , the positioning mechanism 7 includes a protrusion 71 and a concave component 72 . the protrusion 71 is formed on the attachment frame 8 and includes a distal end portion . the distal end portion of the protrusion 71 is formed in a conical shape . the concave component 72 is formed on the panel main body 61 of the decoration panel 6 . the concave component 72 has a conical inner face 73 . the distal end portion of the protrusion 71 fits into the concave component 72 . the positioning mechanism 7 is formed at two places spaced away from each other . therefore , when the protrusions 71 are fitted into the concave components 72 at both of sites of the positioning mechanism 7 in a state in which the decoration panel 6 is pulled toward the attachment frame 8 by the spring body 3 , the decoration panel 6 is positioned at the initial position with respect to the disk tray 5 to which the attachment frame 8 is immovably fixed . the positioning mechanism 7 is provided at two places , namely , two transversal ends in the width direction w ( lengthwise direction ) of the decoration panel 6 and the attachment frame 8 . thus , the positioning accuracy of the decoration panel 6 and the attachment frame 8 , and the positioning accuracy in the initial position of the disk tray 5 and the decoration panel 6 are improved . with the positioning mechanism 7 , the protrusion 71 can be formed on the decoration panel 6 , and the concave component 72 can be formed on the attachment frame 8 . the displacement width restricting mechanism 9 includes a cylindrical shaft 91 and a circular hole 92 . as shown in fig7 , the cylindrical shaft 91 is formed by the same member as the first protrusion 41 . furthermore , the circular hole 92 is formed by the same member as the first opening 84 . the cylindrical shaft 91 is loosely fitted into the circular hole 92 . with the displacement width restricting mechanism 9 , the decoration panel 6 can be displaced in the displacement direction by an amount corresponding to a gap ( that is , the play ) around the cylindrical shaft 91 . in other words , the decoration panel 6 can be displaced in the displacement direction that is perpendicular to the backward and forward directions with respect to the disk tray 5 , but the amount of the displacement is restricted when the cylindrical shaft 91 contacts with an edge portion around the circular hole 92 . the stopper mechanism 10 restricts the amount of compression of the spring bodies 3 so that coils of the spring bodies 3 are not jammed together . as shown in fig7 , the stopper mechanism 10 has a second protrusion 101 , a second opening 102 , a flange ( e . g ., flange portion ) 103 and a receiver ( e . g ., receiving portion ) 104 . the second protrusion 101 is formed in a cylindrical shape . the second protrusion 101 extends from the panel main body 61 . the second opening 102 is formed in a circular shape . the second opening 102 extends through the attachment frame 8 . the flange 103 is attached to the top portion of the second protrusion 101 . the flange 103 is larger in diameter than the second protrusion 101 . the receiver 104 is formed in a round ring - shape . the receiver 104 is formed by the edge portion of the second protrusion 101 . the second protrusion 101 is loosely fitted into the second opening 102 with a gap therebetween . the receiver 104 is opposite the flange 103 with a axial gap inbetween . the gap between the second protrusion 101 and the edge portion of the second opening 102 is wider than the gap around the cylindrical shaft 91 that is loosely fitted in the circular hole 92 . the axial gap between the flange 103 and the receiver 104 is set such that the coils of the spring bodies 3 will not be jammed together even when the flange 103 and the receiver 104 contact each other . the flange 103 is formed integrally with a head portion of a screw 105 . the screw 105 is threaded into the top portion of the second protrusion 101 . specifically , the flange 103 is formed by a flange portion of the screw 105 by using a flanged screw for the screw 105 . fig4 a to 6 illustrate assembly process of the panel attachment structure a . with the panel attachment structure a , the positioning mechanism 7 , the attachment structure of the spring bodies 3 and the stopper mechanism 10 are provided symmetrically at two places at the longitudinal ends of the decoration panel 6 and the attachment frame 8 in the width direction w . as shown in fig4 b , at the initial stage of the assembly process , the attachment frame 8 is aligned overlapping with the panel main body 61 . specifically , the protrusions 71 of the positioning mechanism 7 are fitted into the concave components 72 . as a result , the attachment frame 8 is positioned with respect to the panel main body 61 . also , the second protrusion 101 and the first protrusion 41 of the panel main body 61 are loosely fitted into the second opening 102 and the first opening 84 of the attachment frame 8 , respectively . the cylindrical shaft 91 of the displacement width restricting mechanism 9 also serves as the first protrusion 41 , and the circular hole 92 of the displacement width restricting mechanism 9 also serves as the first opening 84 . thus , the cylindrical shaft 91 is loosely fitted in the circular hole 92 by loosely fitting the first protrusion 41 of the panel main body 61 in the first opening 84 of the attachment frame 8 . in the next step , as shown in fig5 b , the spring body 3 is interposed between the hook component 42 on the attachment frame 8 and the spring seat 85 on the panel main body 61 . this work will be described through reference to fig9 and 10 . first , the spring body 3 is fitted around the first protrusion 41 and the hook component 42 . then , the one axial end portion of the spring body 3 is placed on the spring seat 85 on the panel main body 61 . after this , as shown in fig1 , the latching end portion 31 provided at the other axial end portion of the spring body 3 is aligned with the radial gap s between the hook elements 43 . next , the latching end portion 31 is pushed into the radial gap s while the spring body 3 is compressed , so that the latching end portion 31 is pushed down to the lateral holes 45 . then , the latching end portion 31 is rotated to a location corresponding to the catches 44 through the lateral holes 45 of the hook elements 43 as indicated by the arrow r in fig1 . finally , the force that is pushing the latching end portion 31 is released so that the spring body 3 recovers . as a result , the latching end portion 31 is latched to the catches 44 . when the latching end portion 31 is latched to the catches 44 of the hook elements 43 , a terminal of the latching end portion 31 preferably faces the blind plate 82 of the attachment frame 8 . when the terminal of the latching end portion 31 faces the blind plate 82 , there will be less risk that the worker will be injured by the terminal of the latching end portion 31 . furthermore , there will be less risk that the work will snag a finger or the like on the terminal of the latching end portion 31 . when the assembly process is performed , as shown in fig5 b and 6 , the decoration panel 6 is attached to the attachment frame 8 . specifically , the attachment frame 8 and the decoration panel 6 are linked via the spring bodies 3 . with the panel attachment structure a , the attachment frame 8 is immovably fixed , via the attachment mechanism 83 , to the front end portion of the disk tray 5 that protrudes to outside of the opening 21 of the front panel 1 . with the panel attachment structure a thus attached to the disk tray 5 , the decoration panel 6 is merely linked to the attachment frame 8 by the spring bodies 3 , and the displacement width restricting mechanism 9 merely restricts the displacement width of the decoration panel 6 with respect to the disk tray 5 in the displacement direction . accordingly , as long as the decoration panel 6 does not restrict the displacement width , the decoration panel 6 with respect to the disk tray 5 can be displaced in the displacement direction that intersects the backward and forward directions . as shown in fig1 , when the disk tray 5 moves out toward the ejected position on outside of the cabinet as indicated by the arrow y 1 , the decoration panel 6 sticks out from the recess 2 of the front panel 1 . in this state , since the biasing action of the spring bodies 3 causes the protrusions 71 of the positioning mechanism 7 to be fitted into the concave components 72 , the decoration panel 6 is positioned with respect to the attachment frame 8 . therefore , the decoration panel 6 is positioned in the initial position with respect to the disk tray 5 . the same applies when the disk tray 5 is ejected to the ejected protruding position on the outside of the cabinet . therefore , when the decoration panel 6 is sticking out from the recess 2 of the front panel 1 , the decoration panel 6 is positioned in the initial position with respect to the disk tray 5 . this provides a neat appearance . as shown in fig1 , when the disk tray 5 moves back to the retracted position on the inside of the cabinet as indicated by the arrow y 2 , the decoration panel 6 contacts with the bottom portion 22 of the recess 2 . then , the disk tray 5 slightly compresses the spring bodies 3 . therefore , any error in the retracted position of the disk tray 5 can be easily absorbed by the spring bodies 3 . also , the protrusions 71 of the positioning mechanism 7 are released from the concave components 72 to release the positioned state . accordingly , if the recess 2 is provided with a guide mechanism for guiding the decoration panel 6 to a center position of the recess 2 , then the decoration panel 6 is guided by the guide mechanism and accurately positioned ( centered ) in the center position of the recess 2 . the centering is performed by the decoration panel 6 being displaced with respect to the disk tray 5 or the attachment frame 8 fixed thereto . thus , the adjustment width of the centering does not depend on the size of the assembly looseness of the disk tray 5 with respect to the loader . as shown in fig1 , if the decoration panel 6 is pulled forward in the direction of the arrow y 1 by some kind of external force , such as manually by a person , the decoration panel 6 is forcibly pulled out . if this happens , there is the risk that the spring bodies 3 are compressed too tightly , the coils of the spring bodies 3 is jammed together , and the intended biasing action of the spring bodies 3 is lost . however , the panel attachment structure a has the stopper mechanism 10 . therefore , the flange 103 of the stopper mechanism 10 restricts the amount of compression of the spring bodies 3 by contacting with the receiver 104 . with the panel attachment structure a , the compression coil springs are used as the spring bodies 3 for linking the decoration panel 6 to the attachment frame 8 . fig1 and 15 are perspective views of two kinds of compression coil spring that can be used in the panel attachment structure a . the compression coil spring is formed in the shape of a truncated cone in side view . when the compression coil spring that is formed in the shape of the truncated cone in side view is used for the spring body 3 , it is easy for the diameter of the one axial end portion of the spring body 3 to be matched to the size of the spring seat 85 , and for the diameter of the other axial end portion of the spring body 3 to be matched to the size of the hook component 42 . also , with the compression coil spring , any one of adjacent pairs of coils 32 and 33 that are adjacent to each other in the axial direction are sized so that the diameter of the coil 33 on the side closer to the other axial end portion is smaller than the diameter of the coil 32 on the side closer to the one axial end . the difference between the diameters of the coils 32 and 33 is set such that axial projections of the coils 32 and 33 overlap . that is , when the compression coil spring is viewed in the axial direction , any one of adjacent pair of coils 32 and 33 is set such that the outer periphery of the smaller - diameter coil 32 overlaps the inner periphery of the larger - diameter coil 33 . when a compression coil spring is used as the spring body 3 as shown in fig1 , the latching end portion 31 provided to the other axial end portion sticks out on both radial sides of the coil 34 at the other axial end portion . therefore , when the spring body 3 is compressed too tightly , as illustrated in fig1 , the latching end portion 31 engages with the coil 34 . thus , a situation will not occur in which the latching end portion 31 is jammed inside the coil 34 and the intended biasing action of the spring body 3 is lost . therefore , when the spring body 3 shown in fig1 is used , the stopper mechanism 10 can be omitted . on the other hand , with the compression coil spring shown in fig1 , the latching end portion 31 is designed to be substantially the same size as the diameter of the coil 34 at the other axial end portion . therefore , if the spring body 3 shown in fig1 is compressed too tightly , as illustrated in fig1 , the latching end portion 31 can be jammed inside the coil 34 and the intended biasing action of the spring body 3 can be lost . however , by employing the stopper mechanism 10 , it is possible to prevent the latching end portion 31 from being jammed inside the coil 34 . as shown in fig7 and 10 , the attachment frame 8 further has a circular rib 86 formed around the periphery of the spring seat 85 . the circular rib 86 extends from the periphery of the spring seat 85 . the length of the latching end portion 31 of the spring body 3 shown in fig1 is greater than the outside diameter of the circular rib 86 . more specifically , the length of the latching end portion 31 of the spring body 3 shown in fig1 is greater than the inside diameter of the circular rib 86 . accordingly , even if the spring body 3 shown in fig1 is employed and the stopper mechanism 10 is left out as mentioned above , merely setting the circular rib 86 to a suitable height will result in the engagement of the latching end portion 31 with the circular rib 86 . as a result , the latching end portion 31 is prevented from being jammed inside the coil 34 even if the spring body 3 is compressed too tightly . each of the hook elements 43 of the hook component 42 formed integrally with the panel main body 61 has the hook - shaped catch 44 that opens toward the first protrusion 41 . accordingly , it is conceivable that in addition to a two - piece mold , the mold used to form the panel main body 61 need to be a sliding mold which can slide at a right angle to the parting direction of the mold halves . in view of this , with the panel attachment structure a , an approach is taken whereby the panel main body 61 is molded with a two - piece mold alone . specifically , as shown in fig9 , the first protrusion 41 has cut - out portions ( e . g ., a pair of through holes ) 46 that is cut out along the entire axial length of the first protrusion 41 in the axial direction . the cut - out portions 46 are located opposite the catches 44 and the lateral holes 45 of the hook elements 43 . also , openings 47 that communicate with the cut - out portions 46 of the first protrusion 41 , respectively , are formed in the panel main body 61 . the openings 47 are also shown in fig2 . the cut - out portions 46 and the openings 47 are formed by removing the mold used to form the panel main body 61 . thus , even though the hook elements 43 of the panel main body 61 have the hook - shaped catches 44 that open toward the first protrusion 41 , the mold used to form the panel main body 61 need only be a two - piece mold . thus , there is no need to use the sliding mold . the arrows b 1 and b 2 in fig9 indicate the parting directions of the two - piece mold . the cylindrical shaft 91 and circular hole 92 of the displacement width restricting mechanism 9 can be formed separately at different locations from where the first protrusion 41 and the first opening 84 are formed . specifically , the cylindrical shaft 91 and circular hole 92 of the displacement width restricting mechanism 9 can also serve as the second protrusion 101 and the second opening 102 , respectively . with the panel attachment structure a , the decoration panel 6 can be displaced with respect to the disk tray 5 in the displacement direction that intersects the backward and forward directions . thus , the decoration panel 6 that has been fitted into the recess 2 of the cabinet can be easily centered in the recess 2 . also , a compression coil spring is used for the spring body 3 that links the attachment frame 8 and the decoration panel 6 . thus , it is easier for the spring body 3 to be interposed between the attachment frame 8 and the decoration panel 6 . as a result , the assembly work can be carried out more quickly and easily in a larger space . with the panel attachment structure a , the stopper mechanism 10 restricts the amount of compression of the spring body 3 so that the coils of the spring body 3 are not jammed together . thus , a situation does not occur in which the spring body 3 is compressed too tightly and the coils are jammed together . accordingly , the intended biasing action of the spring body 3 can be achieved . with the panel attachment structure a , the displacement width restricting mechanism 9 has the cylindrical shaft 91 that protrudes from the decoration panel 6 , and the circular hole 92 that is made in the attachment frame 8 . the cylindrical shaft 91 is loosely fitted to the circular hole 92 with the gap therebetween . thus , the displacement width restricting mechanism 9 has a simple configuration . furthermore , the displacement width restricting mechanism 9 does not complicate the configuration of the mold used to form the attachment frame 8 or the decoration panel 6 . with the panel attachment structure a , the positioning mechanism 7 is provided at two places spaced apart . the positioning mechanism 7 has the protrusion 71 and the concave component 72 . the protrusion 71 has the conical distal end portion and is provided to one of the decoration panel 6 and the attachment frame 8 . the concave component 72 is provided to the other of the decoration panel 6 and the attachment frame 8 , and has the conical inner face 73 into which the conical distal end portion of the protrusion 71 fits . thus , even if the disk tray 5 moves out so that the decoration panel 6 sticks out in front of the recess 2 in the front panel 1 , the decoration panel 6 can be properly positioned at the initial position with respect to the disk tray 5 . therefore , the appearance of the decoration panel 6 can be improved . furthermore , the displacement width restricting mechanism 9 does not complicate the configuration of the mold used to form the attachment frame 8 or the decoration panel 6 . with the panel attachment structure a , the attachment frame 8 has the first opening 84 and the spring seat 85 . the first opening 84 extends through the attachment frame 8 . the spring seat 85 supports the one axial end portion of the spring body 3 . the decoration panel 6 has the first protrusion 41 . the first protrusion 41 loosely fits into the first opening 84 with the gap therebetween . the first protrusion 41 has the hook component 42 . the spring body 3 is fitted around the hook component 42 . the hook component 42 latches the other axial end portion of the spring body 3 , thereby keeps the spring body 3 in the compressed state . with this constitution , no extra parts are needed to install the spring body 3 . furthermore , since the hook component 42 that is necessary for installing the spring body 3 is located inside of the spring body 3 , there is no need to leave space outside the spring body 3 for installing the hook component 42 . as a result , the attachment frame 8 can be correspondingly made smaller . with the panel attachment structure a , the spring body 3 has the latching end portion 31 in the form of a straight line that traverses in the radial direction of the coils of the other axial end portion . the hook component 42 sticks out in the axial direction of the first protrusion 41 from the top portion of the first protrusion 41 . the hook component 42 is divided into the hook elements 43 that are opposite each other in the radial direction of the first protrusion 41 . the hook elements 43 have the radial gap s which allows the latching end portion 31 to be inserted . each of the hook elements 43 has the catch 44 on which the latching end portion 31 is caught , and the lateral hole 45 for rotating the latching end portion 31 that has been pushed into the radial gap s around the axis of the spring body 3 and guiding the latching end portion 31 to the catch 44 . the catches 44 and the lateral holes 45 are provided so as to maintain a positional relationship in point symmetry . thus , after the latching end portion 31 of the spring body 3 placed on the spring seat 85 of the attachment frame 8 has been pushed into the radial gap s , the latching end portion 31 is rotated around the axis of the spring body 3 , put into the lateral hole 45 , and guided to the catch 44 . thus , the spring body 3 can be installed by a simple operation . with the panel attachment structure a , the first protrusion 41 is cut out along the entire length in the axial direction at locations opposite the lateral holes 45 and the catches 44 of the hook elements 43 . furthermore , the openings 47 that communicate with the cut - out portions of the first protrusion 41 are formed in the decoration panel 6 . the cut - out portions and the openings 47 are formed by removing the mold used to form the decoration panel 6 . thus , the mold use to form the decoration panel 6 can have a simpler configuration . with the panel attachment structure a , the spring body 3 has the truncated conical shape . the spring body 3 has the adjacent pairs of the coils that are adjacent to one another in the axial direction . the diameter of the coil closer to the one axial end portion is larger than the diameter of the coil closer to the other axial end portion . the difference in the diameters of the adjacent pair of the coils is set such that the axial projections of the coils overlaps . the circular rib 86 is provided around the periphery of the spring seat 85 . the latching end portion 31 sticks out on both sides of the coil at the other axial end portion of the spring body 3 so as to be longer than the outside diameter of the circular rib 86 . with this constitution , a situation does not occur in which the spring body 3 is compressed too tightly and the coils are jammed together . thus , the intended biasing action of the spring body 3 can be achieved . with the panel attachment structure a , the stopper mechanism 10 has the second protrusion 101 , the second opening 102 , the flange 103 and the receiver 104 . the second protrusion 101 protrudes from the decoration panel 6 . the second opening 102 extends through the attachment frame 8 . the second protrusion 101 is loosely fitted into the second opening 102 with the gap therebetween . the flange 103 is attached to the top part of the second protrusion 101 . the flange 103 is larger in diameter than the second opening 102 . the receiver 104 is formed by the edge of the second opening 102 and is opposite the flange 103 . when the flange 103 and the receiver 104 contact , the coils of the spring body 3 are prevented from being jammed together . thus , the intended biasing action of the spring body 3 can be achieved . with the panel attachment structure a , the flange 103 is integrally formed with the screw 105 that is threaded into the top part of the second protrusion 101 . with the panel attachment structure a , the cylindrical shaft 91 of the displacement width restricting mechanism 9 serves as the first protrusion 41 by being in the same location as the first protrusion 41 . the circular hole 92 of the displacement width restricting mechanism 9 also serves as the first opening 84 by being in the same location as the first opening 84 . also , the cylindrical shaft 91 of the displacement width restricting mechanism 9 also can serve as the second protrusion 101 by being in the same location as the second protrusion 101 , and the circular hole 92 of the displacement width restricting mechanism 9 also can serve as the second opening 102 by being in the same location as the second opening 102 . since the spring body 3 is used to displaceably link the decoration panel 6 to the attachment frame 8 fixed to the disk tray 5 , the decoration panel 6 fitted into the recess 2 in the cabinet can be easily centered in the recess 2 . also , because a compression coil spring is used as the spring body 3 , assembly becomes easier than the conventional structure . furthermore , with the panel attachment structure a , the action of the displacement width restricting mechanism 9 prevents the decoration panel 6 from being unnecessarily displaced with respect to the disk tray 5 . furthermore , the action of the positioning mechanism 7 positions the decoration panel 6 in the initial position with respect to the disk tray 5 . thus , the appearance can be improved , even if the disk tray 5 moves out so that the decoration panel 6 sticks out in front of the recess 2 in the cabinet . furthermore , the spring body 3 is prevented from being compressed too tightly . thus , the intended biasing action of the spring body 3 can be obtained . furthermore , the configuration of the mold used to form the decoration panel 6 or the attachment frame 8 can be simplified . in understanding the scope of the present invention , the term “ comprising ” and its derivatives , as used herein , are intended to be open ended terms that specify the presence of the stated features , elements , components and groups , but do not exclude the presence of other unstated features , elements , components and groups . the foregoing also applies to words having similar meanings such as the terms , “ including ”, “ having ” and their derivatives . also , the terms “ part ,” “ section ,” “ portion ,” “ member ” or “ element ” when used in the singular can have the dual meaning of a single part or a plurality of parts . as used herein to describe the present invention , the following directional terms “ forward , rearward , above , downward , vertical , horizontal , below and transverse ” as well as any other similar directional terms refer to those directions of a disk device equipped with the present invention . accordingly , these terms , as utilized to describe the present invention should be interpreted relative to a disk device equipped with the present invention as used in the normal operating position . while a preferred embodiment has been chosen to illustrate the present invention , it will be apparent to those skilled in the art from these disclosures that various changes and modifications can be made herein without departing from the scope of the invention as defined in the appended claims . furthermore , the foregoing descriptions of the preferred embodiment according to the present invention are provided for illustration only , and not for the purpose of limiting the invention as defined by the appended claims and their equivalents .