Patent Publication Number: US-6993778-B2

Title: Recording medium driving device

Description:
This is a continuation of prior application Ser. No. 10/258,993 filed Feb. 6, 2003 now U.S. Pat. No. 6,934,957, which is a 371 of PCT/JP02/02383, filed Mar. 13, 2002. 

   TECHNICAL FIELD 
   The present invention relates to a recording medium driving device for recording information signals and for reproducing the signals for a recording medium. More particularly, the present invention relates to a recording medium driving device in which a recording medium held by a holder is ejected by an ejection lever. 
   BACKGROUND ART 
   There are recording medium driving devices for reproducing information signals recorded on the disc-shaped recording mediums. In certain ones of the recording medium driving devices, a slider held by a holder is moved in one direction when a recording medium is held on the holder to lower the holder to load the recording medium on the loading unit, while the slider is moved in the opposite direction to elevate the holder to eject the recording medium from the holder by an ejection lever. 
   As typical of this sort of the recording medium driving device, there is known a device shown in  FIGS. 1 to 5 . With this driving device, upwardly opened guide grooves  102 ,  102  are formed in both lateral sides of a chassis  101 . In these guide grooves  102 ,  102 , there are slidably supported a pair of rearwardly positioned support pins  104 ,  104  provided on both lateral surfaces of a holder  123 , there being another pair of forwardly positioned similar support pins provided on both lateral surfaces of the holder  123 . 
   On the holder  123 , there is mounted a slider  105  for sliding in the fore-and-aft direction. The slider  105  includes lateral surface sections  106 ,  106  and a connecting portion  107  interconnecting the lateral surface sections  106 ,  106 . In the lateral surface sections  106 ,  106 , there are cam grooves  108 ,  108  which are spaced apart from each other in the in the fore-and-aft direction. In the cam grooves  108 ,  108 , the support pins  104 ,  104  of the holder  123  are supported for sliding movement. A slider biasing spring  109  is mounted under tension between the lateral surfaces  106 ,  106  of the slider  104  and a rearward portion of the chassis  101  for biasing the slider  105  rearwards. 
   At the rear end of the chassis  101 , there is mounted a lever supporting lug  110 , and an ejection lever  111  is rotatably mounted at the foremost part of the supporting lug  110 . A lever biasing spring  112  is mounted under tension between the ejection lever  111  and the holder  123  for biasing the ejection lever  111  in a direction indicated by arrow R 1  in  FIG. 1 . The foremost part of the ejection lever  111  is provided with an operating piece  113  which is bent downwards. 
   Before insertion of the recording medium into the holder  123 , the ejection lever  111  includes a control edge  114  engaged with a mating control edge  116  of the slider  105  so that the slider  105  is held at its foremost movement stroke end (see  FIGS. 1 and 2 ). 
   When a recording medium  117  is inserted from the forward side into the holder  123 , the operating piece  113  of the ejection lever  111  is thrust rearwards by the recording medium  117 , so that the ejection lever  111  is rotated in the direction indicated by arrow R 2  against the bias of the lever biasing spring  112  (see  FIG. 3 ). When the ejection lever  111  is rotated in the direction indicated by arrow R 2  in  FIG. 3 , the control edge  114  is disengaged from the mating control edge  116 , so that the slider  105  is slid rearwards by the slider biasing spring  109  (see  FIG. 4 ). 
   When the slider  105  is moved rearwards, the positions of the support pins  104 ,  104  of the holder  123  in the cam grooves  108 ,  108  are changed, such that the rearward side support pins  104 ,  104  are moved within the guide grooves  102  of the chassis  101  to cause descent of the holder  123  (see  FIG. 5 ). With the descent of the holder  123 , the recording medium  117  which it holds is loaded on a loading unit, not shown, thereby setting up a state enabling the reproducing operation of information signals for the recording medium  117 . The slider  105  is moved rearwards at this time as the mating control edge  116  has a sliding contact with a portion of the ejection lever  111 . The ejection lever  111  has its portion engaged with the mating control edge  116  of the slider  105 , moved rearwards, so that the ejection lever is held at the end of the rotation indicated by arrow R 2 . 
   When the reproducing operation comes to a close, such that an ejection button, not shown, is actuated, a driving motor, not shown, is rotated to cause forward movement of the slider  105  under the driving force of the motor against the biasing force of the slider biasing spring  109 . 
   When the slider  105  is moved forwards, the positions of the support pins  104 ,  104  of the holder  123  in the cam grooves  108 ,  108  are changed, such that the holder  123  is lifted by the rearward side support pins  104 ,  104  being moved in the guide groove  102   b  of the chassis  101 . 
   When the slider  105  has been moved forwards by the ejection lever  111 , the ejection lever  111  is rotated by the lever biasing spring  112  in a direction indicated by arrow R 1 . Consequently, the recording medium  117  is thrust forwards and ejected out of the holder  123  by the operating piece  113  of the ejection lever  111 . 
   When the slider  105  is moved to a forward side preset position, the rotation of the driving motor ceases. The slider  105  is moved rearwards, under the force of the slider biasing spring  109 , and the mating control edge  116  is engaged with the control edge  114  of the ejection lever  111 , which is positioned at the end of the movement stroke in the direction R 1 . The slider  105  again is held at the forward end in the range, of movement. 
   In the above-described recording medium driving device of the related art, described above, the lever biasing spring  112  for biasing the ejection lever  111  and the slider biasing spring  109  for biasing the slider  105  are required, with the consequence that the number of components is correspondingly increased. When inserting the recording medium  117  into the holder  123 , the slider  105 , moved towards rear, has a sliding contact with the ejection lever  111 . Since the lever biasing spring  112  at this time is in the fully stretched state, the frictional resistance between the slider  105  and the ejection lever  111  is large, with the result that the slider  105  and the ejection lever  111  are lowered in durability. Moreover, the load imposed on the driving motor for ejecting the recording medium  117  is increased in an amount corresponding to the increased frictional resistance between the slider  105  and the ejection lever  111 , thus increasing the power consumption. 
   Another instance of the recording medium driving device is a recording and/or reproducing apparatus for recording and/or reproducing information signals for the recording medium. In a certain type of this recording and/or reproducing apparatus, there is such an apparatus in which, when the recording medium is held by the holder, the slider held by the holder is moved in one direction to lower the holder to load the recording medium on the loading unit, and in which, when the slider is moved in the opposite direction, the holder is elevated, at the same time as the recording medium is ejected by the ejection lever from the holder. 
   As this sort of the recording and/or reproducing apparatus, there is such apparatus constructed as shown in  FIGS. 6 and 7 . 
   The recording and/or reproducing apparatus, shown in  FIGS. 6 and 7 , includes a holder  201  movable vertically relative to the chassis. 
   The holder  201  is movable vertically relative to the chassis, not shown. A cam lever  202  is supported by the holder  201  for sliding in the fore-and-aft direction. The cam lever  202  includes a cam  203  and a vertically extending support leg  204 , which support leg  204  is supported for movement in the up-and-down direction in a support opening  205  formed in the chassis. 
   A supporting piece  206  is provided on the upper surface of the holder  201 . The supporting piece  206  rotationally supports a head shift lever  207 . The head shift lever  207  is provided with a mating operating portion  208  that is in sliding contact with the cam  203  of the cam lever  202 . 
   A pickup includes a mounting portion  209 . On the upper surface of the mounting portion  209 , there is mounted a rear end of a head mounting plate  211 , the distal end of which carries a magnetic head  210 . The head mounting plate  211  is formed of an elastic material. 
   The above-described holder  201  and the chassis etc are arranged within an outer casing of the recording and/or reproducing apparatus. A top plate  213  of the outer casing is provided on top of the holder  201 . 
     FIG. 6  shows the state in which the magnetic head  210  is at a first retreat position. During reproduction of information signals from a recording medium, for example, the magnetic head  210  is not in use, so that the magnetic head  210  is retreated from the recording medium held on the holder  201 , and is at the first retreat position. At this time, the mating operating portion  208  of the head shift lever  207  is engaged with the uppermost end of the cam  203  of the cam lever  202 , with the head mounting plate  211  being lifted by the head shift lever  207  in a forwardly descending state. The magnetic head  210  is at a position of being retreated from the recording medium held by the holder  201  right above the upper surface of the holder  201 . 
   When the information signal reproducing operation for the recording medium has been finished, such that the recording medium is ejected forwards from the holder  201 , the holder  201  is moved upwards from the state of  FIG. 58 , while the cam lever  102  is also moved upwards in unison with the holder  201  (see  FIG. 7 ). 
   When the holder  201  and the cam lever  202  are moved upwards, the relative position between the head shift lever  207  and the cam  203  is not changed. However, since the cam  203  is at substantially the same height level as the mounting portion  209 , the magnetic head  210  is moved to a second retreat position with a rising gradient in the forward direction, so that the magnetic head  210  is at a higher height level than the above-mentioned first retreat position (see  FIG. 7 ). 
   In the above-described recording and/or reproducing apparatus of the related art, the head mounting plate  211 , which has been lifted with the forwardly descending gradient, is lifted with a forwardly rising gradient when the recording medium is ejected from the holder  201 . As a consequence, in the recording and/or reproducing apparatus of the related art, there is required a large space between the upper surface of the holder  201  and the outer casing  213  of the outer casing, in order to permit the magnetic head  210  to be moved between the first and second retreat positions, thus increasing the overall thickness of the recording and/or reproducing apparatus. 
   Moreover, the recording medium driving device is designed for recording and/or reproducing information signals for the disc-shaped recording medium loaded on the disc table. This sort of the disc recording and/or reproducing apparatus includes an ejection mechanism for ejecting the disc-shaped recording medium loaded on the disc table on completion of the recording and/or reproduction of the information signals, and a head movement mechanism for causing movement of the magnetic head, adapted for applying the magnetic field to the disc-shaped recording medium during recording, in a direction into contact with or away from the disc-shaped recording medium. 
   In certain versions of this sort of the recording medium driving device, both the operations of the ejection mechanism and the head movement mechanism are operated by the driving power of a sole driving motor, in order to make common use of the sole driving motor. In a disc recording and/or reproducing apparatus of the related art, in which a sole driving motor is used in common, a slider is supported for movement on a holder holding a disc-shaped recording medium, and is moved a first movement amount in one direction with respect to the holder. On completion of the loading, the slider is moved by a second movement amount relative to the holder in the same sole direction by the driving motor to actuate the head movement mechanism, and the magnetic head is moved in a direction of contacting with the so loaded disc-shaped recording medium to set up the recording mode. 
   Consequently, when the recording of the information signals has come to a close, the driving motor is rotated in reverse, while the slider is moved relative to the holder in a direction opposite to the aforementioned one direction by a second amount of movement, with the magnetic head being moved in a direction away from the disc-shaped recording medium to cancel the setting of the recording mode. When the disc-shaped recording medium is to be ejected in the canceled state of the setting of the recording mode, rotation of the driving motor is continued to cause the slider to be moved relative to the holder by the first amount of movement in an opposite direction to the aforementioned one direction to cause the operation of the ejection mechanism. 
   In the above-described driving device of the related art, when the recording of the information signals has come to a close and the disc-shaped recording medium is to be ejected, the slider is moved in the same direction to actuate the ejection mechanism or the head movement mechanism, so that a movement stroke corresponding to the sum of the first and second amounts of movement is required. 
   As a consequence, the recording medium driving device is increased in size by an amount corresponding to the increased amount of the slider movement stroke. 
   There is also a recording medium driving device adapted for driving a disc cartridge in a casing member of which a disc-shaped recording medium is rotatably mounted and in which a shutter is also supported for sliding on the casing member. 
   In such driving device, the shutter is slid by a shutter opening/closing mechanism, usually at the time of inserting the disc cartridge into the holder to open a through-hole formed in the casing member to permit the laser light to be illuminated from a light source of the optical pickup to the disc-shaped recording medium contained in the casing member. 
   The shutter slid is held at an open position, however, if the shutter is vibrated in this case to produce resonant vibrations, it may be impossible to maintain optimum reproducing operations for the disc-shaped recording medium of the disc driving device. 
   In order to combat this inconvenience, a certain disc driving device of the related art includes retention means, such as a spring plate, on a portion of an outer casing, in the inside of which a holder or a chassis is mounted, such that, when the disc-shaped recording medium is loaded on the disc table, the shutter is retained by this retention means to suppress the vibrations which will otherwise be produced. 
   In the recording medium driving device of the related art, in which the retention means are provided at a portion of the outer casing thereof, the vibrations transmitted from outside to the disc driving device tends to be transmitted to the shutter through the retention means, with the result that vibrations cannot be suppressed sufficiently. 
   DISCLOSURE OF THE INVENTION 
   It is an object of the present invention to provide a novel recording medium driving device which overcomes the problems the above-described recording medium driving device of the related art suffers. 
   It is another object of the present invention to provide a recording medium driving device in which it is possible to reduce the number of components and to improve durability of the respective components as well as to reduce the power consumption. 
   It is still another object of the present invention to provide a recording medium driving device in which collision between a recording medium inserted into or ejected from the holder and the magnetic head may be avoided to reduce the size of the apparatus itself. 
   It is a further object of the present invention to provide a recording medium driving device in which the operations of the ejection mechanism and the head movement mechanism are carried out by a sole driving motor to reduce the size of the apparatus itself. 
   It is yet another object of the present invention to provide a recording medium driving device in which vibrations of the shutter ma be efficiently suppressed to assure n optimum operation. 
   For accomplishing the above object, the present invention provides a recording medium driving device including a loading unit for loading a recording medium thereon, and a holder movably carried by a chassis, with the holder holding the recording medium and transporting the recording medium between an insertion/ejection position of inserting or ejecting the recording medium and a loading position of loading the recording medium on the loading unit. The recording medium driving device also includes an ejection lever for ejecting the recording medium from the holder, a slider movable in a direction of inserting the recording medium into the holder and in a direction of ejecting the recording medium from the holder, with the slider causing the holder to be moved to the loading position when the slider is moved in the inserting direction, with the slider causing the holder to be moved to the insertion/ejection position when the slider is moved in the ejecting direction. The recording medium driving device also includes a spring member provided between the ejection lever and the slider for biasing the ejection lever in a direction of ejecting the slider from the holder and for biasing the slider in the inserting direction. 
   Preferably, the ejection lever is rotatably mounted at a corner of the chassis and includes at its one end an operating portion for ejecting the recording medium from the holder, while including at its other end a control portion for controlling the slider towards the ejecting direction. When the recording medium is not loaded on the recording medium driving device, the slider is arranged in the ejecting direction and the operating portion of the ejection lever is biased and rotated in the ejecting direction, the controlling portion engaging with a controlled portion of the slider to control the slider in the ejecting direction. 
   In the recording medium driving device according to the present invention, when the recording medium is introduced into the holder, the operating portion of the ejection lever thrusting the forward end of the recording medium is inserted so that the operating portion is rotated in the inserting direction. The controlling portion is rotated with such rotation to be disengaged from the controlled portion so that the slider is moved in the inserting direction under the bias of the spring member. The slider has a portion thereof engaged with a portion of the other end of the ejection lever to hold the ejection lever at the inserting direction. The holder is moved to the loading position with movement of the slider in the inserting direction for loading the recording medium inserted in the holder to the loading position. 
   Preferably, the recording medium driving device further includes ejection controlling means for causing the slider to be moved in the ejecting direction responsive to a user&#39;s command. The slider is moved in the ejecting direction under control by the ejection controlling means to cause the holder to be moved to the insertion/ejection position and to extend the spring member. The operating portion of the ejection lever is moved in the ejecting direction to eject the recording medium by a portion of the slider being disengaged from a portion of the opposite end of the ejection lever with movement of the slider. The controlling portion of the ejection lever is re-engaged with the controlled portion of the slider to control the slider at the ejecting direction. 
   The present invention also provides a recording medium driving device including a loading unit for loading a recording medium thereon, and a holder for holding the recording medium, which holder is movable between an insertion/ejection position inserting/ejecting the recording medium and a loading position loading the recording medium on the loading unit. The recording medium driving device also includes an ejection lever for ejecting the recording medium from the holder at the inserting/ejecting position, and a slider movable in a direction of inserting the recording medium into the holder and in a direction of ejecting the recording medium from the holder. When the slider is moved in the inserting direction, the slider causes the holder to be moved from the inserting/ejecting position towards the loading position. When the slider is moved in the ejecting direction, it causes the holder to be moved from the loading position to the insertion/ejection position. The recording medium driving device also includes a head for recording information signals on the recording medium, a head shift lever for causing the head to be moved in a direction of contacting with and separating from the recording medium, and a cam lever carried by the holder for movement in the inserting direction and in the ejecting direction. The cam lever operates the head shift lever. The head is retreated to a first retreat position receded from the recording medium as held by the holder, when the recording medium is ejected from the holder positioned at the insertion/ejection position under the driving force of the driving motor. The head is also retreated to a second retreat position receded from the recording medium when information signals are reproduced from the recording medium at the loading position. The holder is moved to the insertion/ejection position when the recording medium is ejected from the holder by a manual operation by a user during the recording of information signals on the recording medium in the loading unit. Also, the head is retreated to a third retreat position receded from the recording medium ejected from the holder. In the first, second and third retreat positions, the relative position between the head and the holder relative to the contacting or separating direction is substantially the same. 
   In this recording medium driving device, the cam lever includes a first cam portion for operating the head shift lever to cause the head to be receded to the first retreat position receded from the recording medium held by the holder when the recording medium is ejected from the holder at the insertion/ejection position, under the driving force of the driving motor, a second cam portion for operating the head shift lever so that, when the information signals are reproduced at the loading unit from the recording medium, the head will be receded to the second retreat position receded from the recording medium, and a third cam portion for operating the head shift lever so that, when the recording medium is ejected by a manual operation of the user when information signals are being recorded on the recording medium in the loading unit, the holder will be moved to the insertion/ejection position, the head being receded to the third retreat position in which the head is receded from the recording medium. 
   The present invention also provides a recording medium driving device including a loading unit for loading a disc thereon, a head movement mechanism for causing a recording head, recording the information signals on a disc loaded on the loading unit, to be moved in a direction of contacting with or separating from the disc, an ejection mechanism for ejecting the disc loaded on the loading unit to outside, a driving gear rotated in one direction or in the other direction by a driving motor, a joint lever which, when the driving gear is rotated in one direction, is moved through the driving gear to operate the ejection mechanism, and a driving lever which, when the driving gear is rotated in the other direction, is moved through the driving gear to operate the head movement mechanism. 
   Preferably, the recording medium driving device further includes a driving power transmitting portion provided to the driving gear for transmitting the driving power of the driving motor, and an operating lever which, when the driving gear is rotated in the other direction, is thrust by the driving power transmitting portion to impart the driving power of the driving motor to the driving lever, and which, when the driving gear is rotated in the one direction, is thrust by the driving power transmitting portion to be receded from the trajectory of the driving power transmitting portion. 
   The present invention also provides a recording medium driving device for driving a disc cartridge including a disc and a cartridge having the disc held therein, with the disc cartridge opening/closing an information recording surface of the disc by a shutter movably mounted in the cartridge. The recording medium driving device includes readout means movable along the radius of the disc for reading out the information from the information recording surface of the disc, a chassis on which the readout means is mounted for movement radially of the disc, a holder movably mounted on the chassis for holding the disc cartridge, a disc table for loading a disc in the disc cartridge as held by the holder, a shutter opening/closing mechanism for opening/closing the shutter, and retention means provided on the chassis or the holder for holding the shutter opened by the shutter opening/closing mechanism when the disc is loaded on the disc table. 
   The retention means may be a spring plate member having one end mounted to the chassis and having retention means at the other end. The retention means is resiliently contacted with the shutter. 
   The retention means may be a detection switch having a mating operating shaft resiliently contacted with the shutter when the holder is moved. By the mating operating shaft being operated by resilient contact with the shutter, the detection switch detects whether or not writing on an information recording surface of the disc is inhibited. 
   Other objects, features and advantages of the present invention will become more apparent from reading the embodiments of the present invention as shown in the drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  show the operation of a recording and/or reproducing apparatus of the related art, and is a plan view showing the state prior to rotation of the ejection lever, 
       FIG. 2  is a side view thereof, showing the state prior to descent of the holder, 
       FIG. 3  is a plan view thereof, showing the state prior to descent of the holder, 
       FIG. 4  is a plan view thereof, showing the state in which the ejection lever has been rotated to shift the slider backwards, and 
       FIG. 5  is a side view thereof showing the state in which the holder has been lowered. 
       FIG. 6  shows the operation of another recording and/or reproducing apparatus of the related art, and is a side view, shown partially in cross-section, and showing the state in which, when the holder has been lowered, the magnetic head has retreated, and 
       FIG. 7  is a schematic enlarged side view, shown partially in cross-section, and showing the state in which, when the holder is lifted, the magnetic head has been retreated. 
       FIG. 8  is a perspective view showing the recording and/or reproducing apparatus to which the present invention is applied, and a disc cartridge. 
       FIG. 9  is a perspective view showing the chassis and respective portions or units supported by the chassis. 
       FIG. 10  is a perspective view showing the inner structure of a disc recording and/or reproducing apparatus according to the present invention. 
       FIG. 11  is a plan view, partially cut away, and showing various portions or units supported by the chassis 
       FIG. 12  is a plan view showing a holder and a cam lever held by the holder. 
       FIG. 13  is an enlarged side view showing the holder and the cam lever held by the holder. 
       FIG. 14  is a plan view showing the holder and the cam lever as well as the slider held by the cam lever. 
       FIG. 15  is an enlarged side view showing the holder and the cam lever as well as the slider held by the cam lever. 
       FIG. 16  is a perspective view showing a chassis. 
       FIG. 17  is a perspective view showing the holder, partially cut away. 
       FIG. 18  is a plan view showing a head shift lever. 
       FIG. 19  is a side view showing the head shift lever. 
       FIG. 20  is a plan view showing a cam lever. 
       FIG. 21  is a side view showing the cam lever. 
       FIG. 22  is a plan view showing a slider. 
       FIG. 23  is a left side view showing the slider. 
       FIG. 24  is a right side view showing the slider. 
       FIG. 25 , showing a sequence of assembling the slider on the holder, is a side view showing the state in which a holder supporting pin is engaged in a lower horizontal portion of a slider cam groove, 
       FIG. 26  is a side view showing the state in which the slider is moved forwards and the holder supporting pin is engaged in the upper horizontal portion of the slider cam groove, 
       FIG. 27  is an enlarged side view showing the state in which the slider has been placed on the holder, and 
       FIG. 28  is an enlarged side view showing the state in which the assembling of the slider on the holder has been completed. 
       FIG. 29  is a plan view showing an ejection lever. 
       FIG. 30  is a front view thereof. 
       FIG. 31  is a side view showing a joint lever. 
       FIG. 32  shows a disc detection switch and is a cross-sectional view showing the switch in the non-operated state, and 
       FIG. 33  is a cross-sectional view showing the switch in the operated state. 
       FIG. 34  is a plan view showing a driving lever. 
       FIG. 35  is a plan view showing a limit lever. 
       FIG. 36  is a plan view showing a converting lever. 
       FIG. 37  is a cross-sectional view showing the converting lever. 
       FIG. 38  is a bottom view showing the limit lever and an operating lever supported by the limit lever. 
       FIG. 39  is a plan view showing the operating lever. 
       FIG. 40  is an enlarged cross-sectional view showing the state of mounting a spring plate member to the chassis. 
       FIG. 41  is a block diagram showing the structure of a portion of the disc recording and/or reproducing apparatus. 
       FIG. 42  shows the operation of the disc recording and/or reproducing apparatus and is a plan view showing the initial state prior to operation of respective portions or units, 
       FIG. 43  is a side view showing the initial state prior to operation of respective portions or units, with a joint lever being omitted, and 
       FIG. 44  is a side view showing the initial state prior to operation of the respective portions or units. 
       FIG. 45  is a plan view showing, of the constituent elements carried by the lower chassis surface, the initial state prior to operation of respective portions or units of the disc recording and/or reproducing apparatus, and 
       FIG. 46  is a side view, shown partially in cross-section, and showing the initial state prior to operation of the respective portions or units as the position relationships between the cam lever and the magnetic head. 
       FIG. 47  is a plan view showing the state in which a disc cartridge is being introduced into a cartridge holder. 
       FIG. 48  is a plan view showing the state in which the slider has been moved to the rear end of its movement stroke. 
       FIG. 49  is a side view showing the state of descent of the holder, with the joint lever being omitted. 
       FIG. 50  is a side view, shown partially in cross-section, and showing the state in which a disc cartridge has been introduced into the cartridge holder and the holder is being lowered, as the position relationships between the cam lever and the magnetic head. 
       FIG. 51  is a side view, shown partially in cross-section, and showing the state of completion of descent of the holder, as the position relationships between the cam lever and the magnetic head. 
       FIG. 52  is a cross-sectional view showing the state in which a spring plate member used as retention means has been resiliently contacted by a shutter. 
       FIG. 53  is a cross-sectional view showing the state in which a mating operating shaft of a disc detection switch used as retention means has been resiliently contacted by the shutter. 
       FIG. 54  is a plan view showing, of the constituent elements supported by the lower surface of the chassis, the state in which a driving gear has been rotated in a first direction and the limit lever has been moved to the forward side end of the movement stroke, while the driving lever has been moved to the rear movement stroke end. 
       FIG. 55  is a side view showing the state in which the magnetic head has been inserted via a head inserting opening in the holder, as the position relationships between the cam lever and the magnetic head. 
       FIG. 56  is a plan view showing, of the constituent elements carried on the lower chassis surface, the state in which the driving gear has been rotated in a second direction, the limit lever has been moved to the rear movement stroke end and the driving lever has been moved to the forward movement stroke end. 
       FIG. 57  is a side view showing the state in which, when the driving gear has been rotated in the second direction, the joint lever is positioned at the rear stroke end. 
       FIG. 58  is a plan view showing, of the constituent elements carried by the lower chassis surface, the state in which the driving gear has been rotated in the second direction and the joint lever has been moved forwards. 
       FIG. 59  is a side view showing the state in which the driving gear has been rotated in the second direction and the joint lever has been moved to the forward movement stroke end. 
       FIG. 60  is a plan view showing the state in which the disc cartridge has been ejected from the holder and in which the slider has been moved forwards. 
       FIG. 61  is a plan view showing, of the constituent elements carried by the lower chassis surface, the state in which the driving gear has been rotated in the second direction and the thrusting lug has a sliding contact with a mating operating edge, with the operating lever having been rotated. 
       FIG. 62  is a side view showing the state in which the thrusting lug of the driving gear is disengaged from the mating operating piece of the joint lever, with the joint lever having been moved to the rear movement stroke end. 
       FIG. 63  is an enlarged plan view showing, of the constituent elements carried by the lower chassis surface, the state in which the detection by a rotation detection switch has been made and the rotation of the driving motor ceases. 
       FIG. 64  is an enlarged side view, partially shown in section, and showing the state in which manual ejection has been performed in the recording mode, as the as the position relationships between the cam lever and the magnetic head. 
   

   BEST MODE FOR CARRYING OUT THE INVENTION 
   In the following, certain preferred embodiments of the present invention will be explained with reference to the drawings. The following embodiments are directed to a disc recording and/or reproducing apparatus in which information signals are recorded on or reproduced from an magneto-optical disc having a diameter of approximately 64 mm, such as Mini-Disc. 
   A recording and/or reproducing apparatus  1 , according to the present invention, has an outer casing  2  of a thin box shape, within which respective members and mechanisms as required are accommodated, as shown in  FIG. 8 . A horizontally elongated rectangular insertion/ejection opening  2   a  is formed in the front surface of the outer casing  2 . The outer casing  2  carries a door  3  for opening/closing the insertion/ejection opening  2   a . If, in introducing the disc cartridge, as later explained, into the outer casing  2 , the disc cartridge is ejected from the outer casing  2 , the door  3  is actuated to open the insertion/ejection opening  2   a . At a preset location of the outer casing  2  are arranged plural operating buttons  4  for performing various functions, as shown in  FIG. 8 . The reproducing operation, the recording operation, cessation of the operation, change of sound volume, ejection of the disc cartridge from the outer casing  2  and various editing functions may be carried out by actuating these operating buttons  4 . 
   Within the outer casing  2 , there is arranged a chassis  5 , as shown in  FIGS. 9 to 11 . The chassis  5  is formed integrally by a major surface portion  6 , side supporting portions  7 ,  8  arranged on left and right side edges of the major surface portion  6 , and a lever supporting portion  9  as well as a lever controlling portion  10 , with the lever supporting portion  9  and the lever controlling portion  10  upstanding from the rear edge of the major surface portion  6  and being spaced apart from each other in the left and right direction, as shown in  FIG. 16 . A pickup mounting opening  6   a  is formed towards the right side of the major surface portion  6 , while a switch mounting opening  6   b  is formed in the forward left side thereof. A retention unit mounting opening  6   c  is formed towards the front right side of the major surface portion  6 . Towards the right side of the major surface portion  6 , positioning pins  11 ,  11  are formed integrally in a staggered relationship in the fore-and-aft direction. Each positioning pin  11  is made up by a positioning projections  11   a  and a support portion  11   b  formed on the rim of the positioning projections  11   a ,  11   a . Towards the left side end of the major surface portion  6  are formed receptacles  12 ,  12  in a staggered relationship in the fore-and-aft direction. The upper surfaces of these receptacles  12 ,  12  are flush with the upper surfaces of the support portions  11   b ,  11   b  of the positioning pins  11 ,  11 . 
   Towards the forward and rear ends of the side supporting portions  7 ,  8  are respectively formed supporting projections  13 ,  14 , which supporting projections  13 ,  14  are formed with forwardly opening supporting grooves  13   a ,  14   a , respectively. On the rear sides of the rear side supporting projections  14 ,  14 , the side supporting portions  7 ,  8  are formed with lugs  15 ,  15 , with portions lying between the supporting projections  14 ,  14  and the lugs  15 ,  15  being opened upwards to serve as guide grooves  15   a ,  15   a . On the upper ends of the supporting projection  14  and the lug  15  of the side supporting portion  7  on the left side, there are formed spring retention pieces  14   b ,  15   b , respectively. 
   The lever supporting portion  9  of the chassis  5  is made up by an upstanding portion  9   a , protruded upwards from the major surface portion  6 , and a supporting portion  9   b  protruded forwards from the upper edge of the upstanding portion  9   a . The lever controlling portion  10  of the chassis  5  is made up by an upstanding portion  10   a , protruded upwards from the major surface portion  6 , and a supporting portion  10   b  protruded forwards from the upper edge of the upstanding portion  10   a . The supporting portion  10   b  is formed with a control opening  10   c  elongated in the forward and aft direction. 
   A holder  16  is vertically movably supported by the side supporting portions  7 ,  8 , as shown in  FIG. 10 . The holder  16  is formed of a plate-shaped elastic metal material, and is formed integrally from a top plate portion  17 , side plate portions  18 ,  19 , and support plates  20 ,  20 , protruded from the lower edges of the side plate portions  18 ,  19  in a direction approaching to each other. The disc cartridge is inserted and held in a flattened spacing defined by the top plate portion  17 , side plate portions  18 ,  19  and the support plates  20 ,  20 . 
   In the top plate portion  17 , a retention spring  17   a  is segmented so that it is slightly inclined towards its distal end. In the top plate portion  17 , there is also formed a head inserting opening  17   b  in register with the pickup mounting opening  6   a  of the chassis  5 . The right side end of the top plate portion  17  is formed integrally with a shift lever restoration spring  17   c  which is protruded rearwards. The left rear end of the top plate portion  17  is formed integrally with a relief opening  17   d.    
   The forward ends of the side plate portions  18 ,  19  of the holder  16  are respectively formed with embossed supports  18   a ,  19   a  which are protruded outwards. The rear ends of the side plate portions  18 ,  19  are formed with outwardly protruded support pins  18   b ,  19   b , respectively. The right side plate portion  19  is provided with a shutter opening/closing mechanism which is formed by a shutter restoration spring  21  and an unlock piece  22  which are formed by partially segmenting the side plate portion  19 . The shutter restoration spring  21  is protruded slightly forwards and is inclined relative to the side plate portion  19  so that its distal end will be positioned inwardly of the side plate portion  19 . The distal end of the shutter restoration spring  21  is bent for protruding inwards and provided as a holding portion  21   a.    
   The unlock piece  22  is extended in the fore-and-aft direction so that its major surface is directed in the up-and-down direction. 
   The forward end of the left side support plate  20  is formed with an operating opening  20   a.    
   The top plate portion  17  of the holder  16  rotatably supports a head shift lever  23 , as shown in  FIGS. 10 ,  12  and  17 . The head shift lever  23  is mounted proximate to the rear end of the head inserting opening  17   b  and is protruded towards the head inserting opening  17   b . From the left side edge of the head shift lever  23 , a rotation controlling piece  23   a  and a mating operating piece  23   b , spaced apart from each other in the fore-and-aft direction, are protruded leftwards, as shown in  FIGS. 18 and 19 . The mating operating piece  23   b  is in the form of a letter V in cross-section, with the apex pointing downwards, when seen from its lateral side, as shown in  FIGS. 18 and 19 . The right side edge of the head shift lever  23  is formed with the rightwardly protruded rotation controlling piece  23   a . The foremost part of the shift lever restoration spring  17   c  provided on the top plate portion  17  of the holder  16  is elastically contacted with the right side end of the head shift lever  23 . As a consequence, the head shift lever  23  is biased so that its foremost part will be moved substantially downwards. 
   A cam lever  24  is supported by the holder  16  for movement in the fore-and-aft direction, as shown in  FIGS. 10 ,  12  and  13 . The cam lever  24  and the head shift lever  23  operate as a head movement mechanism for uplifting and lowering a magnetic head which will be explained subsequently. 
   The cam lever  24  is formed with a supported portion  25 , elongated in the fore-and-aft direction, a protruding portion  26 , protruded rightwards from the supported portion  25  and a cam leg  27  protruded downwards from the supported portion  25 , as shown in  FIGS. 20 and 21 . The supported portion  25  has a plural number of support openings  25   a , elongated in the fore-and-aft direction. The supporting pin  17  or the supporting piece  17   f  provided on the top plate portion  17  is inserted into these support openings  25   a  to permit movement in the fore-and-aft direction. A protruded portion  26  is protruded rightwards from the right side edge of the supported portion  25  so that its foremost part is elongated in the fore-and-aft direction. At the foremost part of the protruded portion  26 , a retention piece  28  and a cam piece  29 , both of which are bent from the foremost portions of the protruded portion  26 , are provided in a spaced-apart relationship to each other. The cam piece  29  is provided, looking from the rear side, with a first cam portion  29   a , a second cam portion  29   b , at a lower portion than the first cam portion  29   a , and a third cam portion  29   c , at a lower portion than the second cam portion  29   b , with the first cam portion  29   a  being at substantially the same height level as the third cam portion  29   c . The portion of the cam leg  27  lower than a mid portion in the vertical direction is formed as a cam portion  30 . This cam portion  30  is made up by an upper portion, extending from an upper position for a short length in the vertical direction, an inclined portion  30   b , contiguous to the upper portion  30   a  and deflected progressively downwards towards rear and a lower portion  30   c  contiguous to the inclined portion  30   b  and extending from the inclined position for a short length in the vertical direction. 
   A slider  31  is supported by the holder  16  for movement in the fore-and-aft direction, as shown in  FIGS. 10 ,  14  and  15 . The slider  31  is made up by a connecting portion  32 , elongated in the left and right direction, extensions  33 ,  34 , protruded rearwards from the left and right ends of the connecting portion  32 , and side portions  35 ,  36  depending from the side edges of the extensions  33 ,  34 , as shown in  FIGS. 22 and 24 . The left side extension  33  is provided with a spring retention projection  33   a , protruded leftwards from the left side edge thereof, and a spring retention projection  33   b , protruded rightwards from the right side edge thereof. A controlled piece  33   c  is provided at the rear end of the extension  33  by bending a portion of the extension  33 . The rear end of the extension is formed with an edge  33   d  inclined so as to be progressively deflected rightwards in the forward direction. The side portions  35 ,  36  are provided with supported pins  35   a ,  36   a , which are spaced apart from each other in the fore-and-aft direction. The side portions  35 ,  36  are also provided with cam grooves  37 ,  38 , which are spaced apart from each other in the fore-and-aft direction. The forward side cam groove  37  is formed with an upper horizontal portion  37   a , an inclined portion  37   b  and a lower horizontal portion  37   c , in this order, beginning from the rear side, with the upper horizontal portion  37   a  being opened rearwards. The rear side cam groove  38  is formed with an upper horizontal portion  38   a , an inclined portion  38   b  and a lower horizontal portion  38   c , in this order, beginning from the rear side, with the lower horizontal portion  38   c  being opened forwards. Directly at back of the cam grooves  37 ,  37 , there is no portion of the slider  31 . Here, relief openings  35   b ,  36   b , opened downwards and rearwards, are formed. 
   The left side portion  35  is formed with thrust pieces  35   c ,  35   d , directly at back and at the rear end of the relief opening  35   b.    
   The slider  31  is assembled to the holder  16  as follows (see  FIGS. 25 to 28 ). 
   First, the slider  31  is connected to the rear side of the holder  16 , as the slider is inclined so that its forward end is positioned upwards, in such a manner that the supporting pins  18   b ,  19   b  of the holder  16  will be inserted into the cam grooves  38 ,  38  of the slider  31  (see  FIG. 25 ). 
   The slider  31  is then moved forwardly of the holder  16  so that the supporting pins  18   b ,  19   b  will be engaged in the rear ends of the cam grooves  38 ,  38  (see  FIG. 26 ). 
   The slider  31  is then rotated relative to the holder  16  until the connecting portion  32  rests on the top plate portion  17 . Since the relief openings  35   b ,  36   b  are formed directly at back of the cam grooves  37 ,  37  of the slider  31 , there is no risk of the slider  31  colliding against the supporting portions  18   a ,  19   a  of the holder  16 , such that, when the connecting portion  32  is set on the top plate portion  17 , the support portions  18   a ,  19   a  of the holder  16  are positioned directly at back of the upper horizontal portions  37   a ,  37   a  of the cam grooves  37 ,  37  (see  FIG. 27 ). 
   Finally, the slider  31  is moved slightly rearwards relative to the holder  16  so that the support portions  18   a ,  19   a  are inserted and engaged in the cam grooves  37 ,  37  from the rear side (see  FIG. 28 ). This causes the slider  31  to be supported by the holder  16  for movement in the fore-and-aft direction. 
   For assembling the slider  31  to the holder  16 , it is only sufficient that the support pins  18   b ,  19   b  are inserted from the forward side into the cam grooves  38 ,  38  of the slider  31 , the slider  31  is then rotated relative to the holder  16  and subsequently the slider is moved towards rear. As a consequence, there is no necessity to provide an allowance in the distance between the slider  31  and the holder  16  in the left and right direction corresponding to the amount of protrusion of the support portions  18   a ,  19   a  and the support pins  18   b ,  19   b  from the side plate portions  18 ,  19 , respectively. The result is that the width in the left and right direction of the slider  31  may be correspondingly reduced to reduce the size of the disc recording and/or reproducing apparatus  1 . 
   On the lever supporting portion  9  of the chassis  5 , an ejection lever  39  is supported for rotation, as shown in  FIGS. 9 and 10 . As for the slider  31  and the ejection lever  39 , the ejection lever  39 , operating as an ejection mechanism for ejecting the disc cartridge held by the holder  16  from the holder  16 , is formed integrally by a rotation fulcrum point  40 , a control projection  41  protruded from the rotation fulcrum point  40 , a protrusion  42  extending from the rotation fulcrum point  40  in a direction substantially perpendicular to the control projection  41  and an operating portion  43  extending downwards from the distal end of the protrusion  42 , as shown in  FIGS. 29  and  30 . The control projection  41  has its distal end edge formed as a control edge  41   a  contacted with the controlled piece  33   c  of the slider  31 . A roll  44  is carried for rotation by the distal end of the control projection  41 . This roll  44  is carried as it is protruded downwards from the control projection  41 . The forward edge of the protrusion  42  has a spring retainer  42   a , while its rear edge includes an insertion piece  42   b  bent downwards. The insertion piece  42   b  is inserted into the control opening  10   c  of the lever controlling portion  10  of the chassis  5 . Rotation of the ejection lever  39  in a forward direction indicated by arrow R 1  in  FIG. 10  is controlled by the insertion piece  42   b  contacting with the forward opening edge of the control opening  10   c.    
   The holder  16 , carrying the cam lever  24  and the slider  31 , is slidably engaged from an inner side in guide grooves  15   a ,  15   a  of the side supporting portions  7 ,  8  of the chassis  5 , as the support pins  18   b ,  19   b  are protruded from the cam grooves  38 ,  38  of the slider  31 . The slider  31 , carried by the holder  16 , has the supported pins  35   a ,  36   a  slidably engaged from the inner side in the supporting grooves  13   a ,  14   a  of the side supporting portions  7 ,  8  of the chassis  5 . As a consequence, the holder  16  is movable in the vertical direction relative to the chassis  5  along with the cam lever  24 . The slider  31  is movable in the fore-and-aft direction relative to the holder  16 , by the support portions  18   a ,  19   a  and the support pins  18   b ,  19   b  being moved in the cam grooves  37 ,  38  of the slider  31  during movement of the holder  16 . 
   When the holder  16  has been supported by the chassis  5  as described above, a spring member  45  as a tension coil spring is mounted under tension between the spring retainer  42   a  of the ejection lever  39 , rotatably carried by the lever supporting portion  9 , and the spring retention projection  33   b  of the slider  31  (see  FIG. 10 ). As the ejection lever  39  is biased in a direction indicated by arrow R 1  in  FIG. 10 , the slider  31  is biased rearwards, with the controlled piece  33   c  of the slider  31  being contacted with the control edge  41   a  of the control projection  41  of the ejection lever  39 , positioned at the stroke end of rotation in the direction indicated by arrow R 1  in  FIG. 10 , to control the rearward movement of the slider  31 . 
   Between the spring retention projection  33   a  of the slider  31  and the spring retention piece  14   b  of the side supporting portion  7  of the chassis  5 , an auxiliary spring  46 , having a spring force weaker than the spring force of the spring member  45 , is mounted under tension. This also biases the slider  31  rearwards (see  FIG. 10 ). 
   On the side supporting portion  7 , a joint lever  47  is supported for movement in the fore-and-aft direction, as shown in  FIGS. 9 and 10 . The joint lever  47  is elongated in the fore-and-aft direction and is formed with supported openings  47   a ,  47   a  which are spaced apart from each other in the fore-and-aft direction (see  FIG. 31 ). The forward lower edge of the joint lever  47  is formed with a mating operating piece  47   b , whereas the upper edge of the joint lever between the paired supported openings  47   a ,  47   a  thereof is formed with an upwardly projecting thrusting piece  47   b . A spring retainer  47   d  is formed above the rear supported opening  47   a  of the joint lever  47 . The rear end of the joint lever  47  is bent rightwards to form a thrusting portion  47   e . The support pins  7   a ,  7   a  provided on the side supporting portion  7  are inserted into the supported openings  47   a ,  47   a  of the joint lever  47  so as to be carried for movement in the fore-and-aft direction. With the joint lever  47  supported by the side supporting portion  7 , a tension coil spring  48  is mounted under tension between the spring retainer  47   d  and the spring retention piece  15   b  of the side supporting portion  7  for biasing the joint lever  47  rearwards. 
   At a mid portion of the major surface portion  6  of the chassis  5 , a spindle motor, not shown, is mounted, and a disc table  49  is secured to a motor shaft of the spindle motor (see  FIGS. 2 and 4 ). The disc table  49  includes a centering boss  49   a , fitted in a center opening of a disc-shaped recording medium, and a table  49   b  on which is set an inner rim of the disc-shaped recording medium. A suction magnet, not shown, is embedded in the centering boss  49   a.    
   Within the pickup mounting opening  6   a  of the major surface portion  6 , an optical pickup  50  is mounted for movement radially of the disc-shaped recording medium, as shown in  FIGS. 9 and 11 . The optical pickup  50  includes a biaxial actuator  52 , having an objective lens  52   a , carried on a movable base  51 . The movable base  51  has its forward and rear ends carried for sliding movement by guide shafts  53 ,  54  mounted on the lower surface of the major surface portion  6 , respectively. A nut, not shown, provided on the movable base  51 , is engaged with a lead screw  55  provided on the lower surface of the major surface portion  6 . The lead screw  55  is rotated by a feed motor  56  provided on the lower surface of the major surface portion  6 . When the lead screw  55  is rotated by the feed motor  56 , the nut meshing with the lead screw  55  is fed along the axial direction of the lead screw  55 , whereby the optical pickup  50  is guided by the guide shafts  53 ,  54  so as to be moved along the radius of the disc-shaped recording medium. 
   The rear end of the optical pickup  50  carries the lower surface of a U-shaped connecting member  57  with the opening of the letter U being opened forwards when seen from the lateral side. The connecting member  57  includes an intermediate portion, lying directly at back of the rear edge of the major surface portion  6 , while having an upper surface portion lying directly above the rear end of the holder  16  (see  FIG. 10 ). On the upper surface of the connecting member  57  are mounted a head mounting arm  58  and an arm control plate  59  for controlling excess upward shifting of the head mounting arm  58  (see  FIG. 10 ). The head mounting arm  58 , formed by an elastic metal sheet of a thin thickness, is elongated in the fore-and-aft direction, and has its rear end mounted to the connecting member  57 . The head mounting arm is set at a mid portion thereof in the fore-and-aft direction on the head shift lever  23  carried by the holder  16 . A magnetic head  58   a  is mounted on the forward end of the head mounting arm  58  directly on top of the objective lens  52   a  of the biaxial actuator  52 . The arm control plate  59  is elongated in the fore-and-aft direction, and has its rear end mounted to the connecting member  57  from above the head mounting arm  58 . The arm control plate includes lateral projections for holding the head mounting arm  58  from above. 
   Since the optical pickup  50  and the head mounting arm  58  are interconnected by the connecting member  57 , the head mounting arm  58 , carrying the optical pickup  50  and the magnetic head  58   a , may be moved in unison along the radius of the disc-shaped recording medium. 
   A circuit board  60  is mounted on the forward lower surface of the major surface portion  6  of the chassis  5 , and carries plural disc detection switches  61  on the forward left end of the major surface portion  6  of the chassis  5 , as shown in  FIG. 9 . A disc detection switch  61  is mounted via a connection board  62 , mounted in turn on the circuit board  60 , and includes a switch casing  63  and a mating operating shaft  64  vertically movably supported on the switch casing  63 , as shown in  FIGS. 32 and 33 . The switch casing  63  includes a rectangular bottom surface  63   a , a peripheral wall section  63   b , upstanding from the periphery of the bottom surface  63   a  and an anti-extrication portion  63   c  projected inwards from the peripheral wall section  63   b . The lower end of the peripheral wall section  63   b  includes contacts  63   d ,  63   d . The mating operating shaft  64  is arbor-shaped, with the diameter of a lower end  64   a  being thicker in thickness than the other portions. The operating shaft includes a pair of contacts  64   b ,  64   b  provided on its lower end  64   a . A compression spring  65  is mounted under compression between the bottom surface  63   a  of the switch casing  63  and the lower surface of the mating operating shaft  64 , so that the mating operating shaft  64  is biased upwards. When the mating operating shaft  64  is not acted on, the lower end  64   a  is engaged with the anti-extrication portion  63   c  of the switch casing  63 , thus establishing a non-detection state in which the contacts  64   b ,  64   b  are not connected to the contacts  63   d ,  63   d , as shown in  FIG. 32 . When the mating operating shaft  64  is acted on by being thrust downwards by the disc cartridge, the contacts  64   b ,  64   b  are connected to the contacts  63   d ,  63   d  to set up a detection state. 
   On the leftward lower surface portion of the circuit board  60 , a rotation detection switch  66  is mounted as shown in  FIG. 11 . A mating operating portion  66   a  of the rotation detection switch  66  is protruded substantially laterally. 
   On the lower left surface portion of the major surface portion  6 , a driving lever  67  is mounted for movement in the fore-and-aft direction, as shown in  FIG. 11 . The driving lever  67  is elongated in the fore-and-aft direction and is formed with supported openings  67   a ,  67   a  at the forward and rear ends thereof (see  FIG. 34 ). The forward end of the driving lever  67  is formed with an engagement opening  67   b . In this engagement opening  67   b  is inserted and engaged the cam leg  27  of the cam lever  24 . The rearward end of the driving lever  67  is formed with a connection opening  67   c , while the mid portion thereof in the fore-and-aft direction is formed with a spring retention piece  67   d.    
   By the support pins  6   d ,  6   d  on the lower surface of the major surface portion  6  being inserted into the supported openings  67   a ,  67   a  of the driving lever  67 , and by the cam leg  27  of the cam lever  24  being inserted and engaged with the engagement opening  67   b , the cam lever  24  is moved in the fore-and-aft direction with movement of the driving lever  67  in the fore-and-aft direction. Between the spring retention piece  67   d  and a spring retention projection  6   e  provided on the lower surface of the major surface portion  6 , a tension coil spring  68  is mounted under tension for biasing the driving lever  67  in the forward direction, as shown in  FIG. 11 . 
   On the lower surface of the major surface portion  6 , a limit lever  69  is mounted for movement in the fore-and-aft direction, in a side-by-side relationship to the driving lever  67 , as shown in  FIG. 11 . The limit lever  69  is elongated in the fore-and-aft direction and is formed at forward and rear ends with supported openings  69   a ,  69   a  (see  FIG. 35 ). Towards the forward end of the limit lever  69 , there is provided a lever supporting portion  69   b . A support shaft  69   c  is mounted in rear of the lever supporting portion  69   b . The limit lever  69  has a spring retention opening  69   d  and a forwardly directed support piece  69   e  on the right-hand side and on the left-hand side of the support shaft  69   c , respectively. The limit lever  69  is formed with a thrust piece  69   f  at back of the support piece  69   e , while being formed with a connection opening  69   g  towards its rear end. In the supported openings  69   a ,  69   a  of the limit lever  69 , support pins  6   f ,  6   f  provided on the lower surface of the major surface portion  6  are inserted and carried for movement in the fore-and-aft direction (see  FIG. 11 ). A stop edge  6   g  formed on the major surface portion  6  of the chassis  5  is positioned ahead of the support piece  69   e  of the limit lever  69  (see  FIG. 11 ). 
   The driving lever  67  and the limit lever  69  are interconnected by a conversion lever  70 , as shown in  FIG. 11 . The conversion lever  70  has a center supported tube  70   a  and upwardly projecting connection pins  70   b ,  70   b  on both sides of the supported tube  70   a  (see  FIGS. 36 and 37 ). 
   A support shaft  6   h  of the conversion lever  70 , provided between the driving lever  67  on the lower surface of the major surface portion  6  and the limit lever  69 , is inserted into the supported tube  70   a , for rotation relative to the major surface portion  6 , as shown in  FIG. 11 . The connection pins  70   b ,  70   b  are rotatably engaged in the connection opening  67   c  of the driving lever  67  and in the connection opening connection opening  69   g  of the limit lever  69 . As a result, the driving lever  67  and the limit lever  69  are moved in the opposite directions in the fore-and-aft direction. 
   The lower surface of the limit lever  69  rotatably carries an operating lever  71 , as shown in  FIGS. 11 and 38 . The operating lever  71  is substantially L-shaped and has its one end formed as a rotation fulcrum point  71   a , which rotation fulcrum point  71   a  is rotatably carried by the lever supporting portion  69   b  of the limit lever  69  (see  FIGS. 38 and 39 ). The bent portion of the operating lever  71  is formed with a short arcuate guide opening  71   b . The support shaft  69   c  of the limit lever  69  is inserted into the guide opening  71   b . The operating lever  71  is rotatable relative the limit lever  69  within an extent of the guide opening  71   b.    
   The operating lever  71  has its distal edge bent to from a curved mating operating edge  71   c , and includes a linear controlled edge  71   d  and a linear thrust edge  71   e  on both opposite sides of the mating operating edge  71   c.    
   A spring retention projection  71   f  is protruded from the rotation fulcrum point  71   a  of the operating lever  71 . A tension spring  72  is mounted under tension between the spring retention projection  71   f  and the spring retention opening  69   d  of the limit lever  69 . Thus, the operating lever  71  is biased counterclockwise in the plane of  FIG. 11 . Except if the force in the clockwise direction in  FIG. 11  is accorded to the operating lever  71  in  FIG. 11 , the controlled edge  71   d  is contacted with the support piece  69   e  of the limit lever  69 . 
   A driving motor  73  is mounted on the lower surface of the major surface portion  6  of the chassis  5 , and drives a gear set  74 , made up of four gears, carried on the lower surface of the major surface portion  6  (see  FIG. 11 ). A switching gear  75  meshes with the fourth gear of the gear set  74  counted from the side of the driving motor  73  (see  FIG. 11 ). An operating boss  75   a  is formed as one with the lower surface of the switching gear  75 . Rotation of the switching gear  75  actuates the mating operating portion  66   a  of the rotation detection switch  66 . When the mating operating portion  66   a  is actuated, rotation of the driving motor  73  ceases transiently. 
   A driving gear  76  meshes with the switching gear  75 . The upper surface of the driving gear  66  is formed with a thrusting boss  76   a  (see  FIG. 11 ). The thrusting boss  76   a  plays the role of a driving power transmission for transmitting the driving power of the driving motor  73  through the limit lever  69 , conversion lever  70  and the driving lever  67  to the cam lever  24 , as a portion of the head movement mechanism, and of transmitting the driving power of the driving motor  73  through the joint lever  47  to the slider  31  as a portion of the ejection mechanism. The driving gear  76  is mounted at such a position that the thrusting boss  76   a  is able to thrust the thrust piece  69   f  of the limit lever  69 , the mating operating edge  71   c  of the operating lever  71  and the thrust edge  71   e  of the operating lever  71 . 
   A spring plate member  77 , which plays the role of retaining a shutter, as later explained, of the disc cartridge, is mounted between the major surface portion  6  of the chassis  5  and the circuit board  60  (see  FIGS. 9 and 40 ). The spring plate member  77  has its one end  77   a  mounted on the major surface portion  6 . The portion of the spring plate member towards the other end thereof is formed as an upwardly protruding retainer  77   b , which retainer  77   b  is projected upwards through the retention unit mounting opening  6   c  (see  FIG. 40 ). The upper end of the retainer  77   b  is positioned above the support portion  11   b  of the positioning pin  11  provided on the major surface portion  6  and the receptacle  12  (see  FIG. 40 ). 
   The circuit board  60  carries a controller (micro-computer) including a central processing unit (CPU)  78  (see  FIG. 41 ). The controller  78  sends a control signal to each component based on a detection signal yielded on actuation of the disc detection switch  61  and the rotation detection switch  66 . The controller  78  also sends a control signal to each component based on an operating signal yielded on actuation of any of the operating buttons  4  provided on the outer casing  2 . 
   The driving motor  73  is run in rotation or halted based on a control signal sent from the controller  78  through a motor driver  79 . The optical pickup  50  is driven or halted based on a control signal sent from the controller  78  through an optical pickup driver  80 . The feed motor  56  and the spindle motor are also driven or halted based on the control signal input from the controller  78 . 
   The disc cartridge  120  includes a flattened rectangular box-shaped casing  121 , within which a magneto-optical disc  122  as a disc-shaped recording medium is rotationally mounted, as shown in  FIG. 8 . Centrally of the lower surface of the casing  121  is formed an insertion opening, not shown, and a through-hole, not shown, is formed laterally of the insertion opening. In the upper surface of the casing  121 , there is formed, in register with the through-hole, a head access opening  121   a , into which is inserted the magnetic head  58   a . In the casing  121  is slidably mounted a shutter  123  for opening or closing the through-hole and the head access opening  121   a . In the lateral surface of the casing  121  carrying the shutter  123  is formed a groove  121   b  extending in the fore-and-aft direction. In the lateral surface of the shutter  123  is formed an engagement opening  123   a . The shutter is locked by a lock mechanism, not shown, provided in the casing  121 , in a state in which the shutter has closed the through-hole and the head access opening  121   a . In the lower surface of the casing  121  are formed positioning openings, not shown, separated from each other in the fore-and-aft direction. 
   The center portion of the disc-shaped recording medium  122  is formed with a center opening, on an opening edge of which is fitted a hub formed of a magnetic metal material. 
   The operation of the disc recording and/or reproducing apparatus  1  is hereinafter explained (see  FIGS. 42 to 64 ). 
   First, the state prior to the loading of the disc cartridge  120  is explained (see  FIGS. 42 to 46 ). 
   The ejection lever  39  is positioned at the end of the rotational stroke in the direction indicated by arrow R 1  in  FIG. 42 . The controlled piece  33   c  of the slider  31  is contacted with the control edge  41   a  of the control projection  41 , under the force of the spring member  45 , for holding the slider  31  at a forward position (see  FIG. 42 ). Thus, the support portions  18   a ,  19   a  and the support pins  18   b ,  19   b  of the holder  16  are engaged in the upper horizontal portions  37   a ,  38   a  of the cam grooves  37 ,  38  of the slider  31 , and hence the holder  16  is held at an upper movement stroke end, that is at a position of inserting or ejecting the disc cartridge  120  (see  FIG. 43 ). 
   The joint lever  47 , carried by the side supporting portion  7 , is held at the rear stroke end under the force of the tension coil spring  48 , as shown in  FIG. 7 . The switching gear  75 , carried by the lower surface of the major surface portion  6  of the chassis  5 , is halted in contact with the mating operating portion  66   a  of the rotation detection switch  66 , while the driving gear  76  is at a position in which the thrusting boss  76   a  abuts against or in proximity to the thrust piece  69   f  of the limit lever  69 , that is at a reference position (see  FIG. 38 ). The limit lever  69  is positioned at the rear stroke end, while the operating lever  71  supported by the limit lever  69  is in such a state in which the controlled edge  71   d  is kept in abutment against the support piece  69   e  of the limit lever  69  (see  FIG. 45 ). Since the limit lever  69  is at the rear stroke end, the driving lever  67 , connected to the limit lever  69  through the conversion lever  70 , is positioned at the forward stroke end (see  FIG. 45 ). 
   Since the driving lever  67  is at the forward stroke end and the holder  16  is held at the insertion/ejection position, the cam lever  24  has the lower portion  30   c  of the cam leg  27  engaged in the engagement opening  67   b  of the driving lever  67  (see  FIGS. 43 and 46 ). The cam lever  24  is positioned at the forward end of the movement stroke (see  FIG. 42 ). Thus, the head shift lever  23  is kept at a first retreat position in which the mating operating piece  23   b  is engaged in the first cam  29   a  of the cam lever  24 , the head mounting arm  58  is substantially at a horizontal position and the magnetic head  58   a  is not collided against the disc cartridge being introduced into the holder  16  (see  FIG. 46 ). 
   When the disc cartridge  120  is inserted through the insertion/ejection opening  2   a  of the outer casing  2 , the door  3  is rotated, and the disc cartridge  120  is inserted into the holder  16  (see  FIG. 47 ). The operating portion  43  of the ejection lever  39  is thrust towards rear by the inserted disc cartridge  120 , so that the ejection lever  39  is rotated in the direction indicated by arrow R 2  in  FIG. 47  against the force of the spring member  45 . 
   As the disc cartridge  120  is inserted into the holder  16 , the lateral side of the casing  121  is brought into sliding contact with the shutter restoration spring  21 , provided on the side plate portion  19  of the holder  16 , so that the shutter restoration spring  21  is flexed outwards. The unlock piece  22  then is moved forwards in the groove  121   b  of the disc cartridge  120  to unlock the shutter  123 . The unlock piece then thrusts the edge of the shutter  123  to cause the sliding of the shutter  123 . As the shutter  123  is slid, the holding portion  21   a  of the shutter restoration spring  21  is engaged in the engagement opening  123   a  of the shutter  123  to hold the disc cartridge  120  within the holder  16 . As the shutter  123  is slid, the through-hole and the head access opening  121   a  formed in the casing member  121  are opened. 
   When the disc cartridge is inserted into the holder  16 , the retention spring  17   a  provided to the top plate portion  17  of the holder  16  is brought into resilient contact with the casing member  121  of the disc cartridge  120  to hold the casing member  121 . 
   When the ejection lever  39  is rotated in the direction indicated by arrow R 2  in  FIG. 48  and the control edge  41   a  is disengaged from the controlled piece  33   c  of the slider  31 , the slider  31  is moved rearwards under the force of the spring member  45 . Since the slider  31  is also pulled rearwards by the auxiliary spring  46 , mounted under tension between the spring retention projection  33   a  and the spring retention piece  14   b  of the side supporting portion  7  of the chassis  5 , the slider  31  is positively moved to the rear movement stroke end. 
   When the slider  31  is moved rearwards, the roll  44  supported by the ejection lever  39  rolls on the inclined edge  33   d , so that the slider  31  is smoothly moved rearwards as shown in  FIG. 48 . 
   Although the auxiliary spring  46  is used in the disc recording and/or reproducing apparatus  1  of the present invention, such auxiliary spring  46  may be dispensed with subject to proper adjustment of the force of the spring member  45 . As a consequence, only the spring member  45  suffices, and hence the number of components may be reduced. 
   With the disc recording and/or reproducing apparatus  1  of the present invention, the length of the extended spring member  45  is progressively shortened as the slider  31  is moved rearwards, as described above. Thus, the slider  31  and the ejection lever  39  may be improved in durability, and hence the load on the driving motor  73  in ejecting the disc cartridge  120 , as later explained is relieved to lower the power consumption in an amount corresponding to the diminished frictional resistance of the slider  31  and the ejection lever  39 . In addition, the spring force of the spring member  45  may be reduced due to reduction in the load. 
   As the slider is moved rearwards, the support portions  18   a ,  19   a  and the support pins  18   b ,  19   b  of the holder  16  perform relative movement from the upper horizontal sections  37   a ,  38   a  of the cam grooves  37 ,  38  and the inclined sections  37   b ,  38   b  to the lower horizontal sections  37   c ,  38   c  (see  FIG. 49 ). Thus, the holder  16  is moved to the lower end of the movement stroke, as it is guided by the guide grooves  15   a ,  15   a  formed in the side supporting portions  7 ,  8 , until the holder gets to the loading position in contact with the major surface portion  6  of the chassis  5 . When the holder  16  is moved downwards, the cam lever  24  is also moved downwards, with movement of the holder  16 . The cam lever  24 , the lower portion  30   c  of the cam leg  27  of which has been engaged in the engagement groove  67   b  of the driving lever  67 , is moved through the inclined section  30   b  (see  FIG. 50 ) until the upper side section  30   a  is engaged in the engagement groove  67   b , with the cam lever  24  being moved slightly rearwards relative to the holder  16  (see  FIGS. 41 to 44 ). The result is that the head shift lever  23  has its mating operating piece  23   b  engaged in the second cam portion  29   b  of the cam lever  24 , so that the head shift lever is raised in its forward portion (see  FIG. 51 ). Since the holder  16  has been lowered, the head mounting arm  58  has its forward portion lowered. However, the head shift lever  23  has its forward portion elevated, and hence the magnetic head  58   a  is kept at the second retreat position directly overlying the top plate portion  17  of the holder  16  and is not introduced into the head inserting opening  17   b . In terms of the relative position of the holder  16  relative to the top plate portion  17 , this second retreat position is substantially the same as the aforementioned first retreat position. 
   When the holder  16  gets to the loading position corresponding to the lower end of its movement stroke, the disc table  49  is inserted via an insertion opening of the casing member  121  of the disc cartridge  120 , held by the holder  16 , so that the centering boss  49   a  of the disc table  49  is introduced into the center opening of the disc-shaped recording medium  122 , while the hub of the disc-shaped recording medium  122  is sucked by a magnet provided on the centering boss  49   a , whereby the disc-shaped recording medium  122  is loaded on the disc table  49 . 
   When the holder  16  is moved downwards, the operating shafts  64 ,  64 ,  64  of the disc detection switches  61 ,  61 ,  61  are thrust and actuated by the casing member  101  of the disc cartridge  120  for use for write protect detection, AD/MD-DATA2 (trademark) detection and disc reflectance detection, that is for detection whether the disc is a ROM (optical disc carrying information signals as pits) or a RAM (magneto-optical disc). A loading detection switch for detecting whether the disc-shaped recording medium  122  has been loaded on the disc table  49  is provided as a separate unit, even though such loading detection switch is not shown. Alternatively, the disc detection switch  61  may be used to detect that the disc-shaped recording medium  122  has been loaded on the disc table  49 . 
   When the disc-shaped recording medium  122  has been loaded on the disc table  49 , the inner edge of the disc-shaped recording medium  122  is set on the table portion  49   b , while the disc-shaped recording medium  122  is positioned at a location slightly above the inner lower surface of the casing member  121 . 
   When the disc-shaped recording medium  122  has been loaded on the disc table  49 , the positioning projections  11   a ,  11   a  of the positioning pins  11 ,  11  provided on the major surface portion  6  of the chassis  5  are introduced into the positioning openings of the casing member  121  for positioning the disc cartridge  120  relative to the chassis  5 . When the disc cartridge  100  has been positioned relative to the chassis  5 , the casing member  121  is set on the support portion  11   a  of the positioning pin  11  and on the receptacle  12  (see  FIG. 52 ). The retainer  77   b  of the spring plate member  77 , mounted on the lower surface of the major surface portion  6 , is brought into resilient contact with the shutter  123  of the disc cartridge  120  at this time from the lower side (see  FIG. 52 ). Consequently, the vibrations of the shutter  123  during the reproduction and recording of the disc-shaped recording medium  122  can be suppressed to assure optimum reproducing and recording operations. 
   Since the spring plate member  77  for suppressing the vibrations of the shutter  123  is mounted on the chassis  5  arranged within the outer casing  2 , the vibrations otherwise transmitted from outside to the disc recording and/or reproducing apparatus  1  can scarcely be transmitted through the spring plate member  77  to the shutter  123  to suppress the vibrations efficiently and sufficiently. 
   Moreover, since the spring plate member  77 , having its one end  77   a  mounted on the major surface portion  6  of the chassis  5 , is used as retention means for holding the shutter  123  to suppress its vibrations, the vibrations to the shutter  123  may be effectively prohibited by a simplified structure, such that provision of retention means does not raise the cost. 
   In the foregoing description, the spring plate member  77  is used as retention means. Alternatively, the disc detection switch  61  may also be used as retention means in place of the spring plate member  77  (see  FIG. 53 ). In this case, the disc detection switch  61  is arranged on the circuit board  60  at such a position that the mating operating shaft  64  is projected upwards from the retention unit mounting opening  6   c  formed in the major surface portion  6 , in place of arranging the disc detection switch  61  provided at the left end of the circuit board  60 . 
   When the holder  16  is lowered, the mating operating shaft  64  is brought into resilient abutting contact from below against the shutter  123  of the disc cartridge  120 , under the spring force of the compression coil spring  65 , to suppress the vibrations of the shutter  123 . At the same time, the loading of the disc-shaped recording medium  22  on the disc table  49  is detected by the operation on the mating operating shaft  64 . Thus, if the disc detection switch  61  is used as retention means, suppression of vibrations of the shutter  123  and the above detection can be achieved simultaneously, so that there is no necessity of providing dedicated retention means in addition to the disc detection switch  61 , thus achieving reduction in the number of component parts and in cost. 
   As the retention means, the spring plate member  77  and the disc detection switch  61  may be used in combination. 
   If, when the holder  16  carrying the disc cartridge  120  is lowered and the disc-shaped recording medium  122  has been loaded on the disc table  49 , a replay button (operating button)  4 , provided on the outer casing  2 , is actuated, the disc table  49  and hence the disc-shaped recording medium  122  are run in rotation by the driving of the spindle motor, while the optical pickup  50  is guided by the guide shafts  53 ,  54  by the driving of the feed motor  56  and hence is moved radially of the disc-shaped recording medium  122 . At this time, a laser light beam is illuminated from the objective lens  52   a  of the biaxial actuator  52  of the optical pickup  50  through the through-hole of the casing member  121  to the disc-shaped recording medium  122  to reproduce information signals. 
   If a stop button (operating button)  4  is actuated, the rotation of the disc table  49  is halted, while the optical-pickup  50  ceases to be operated to stop the reproduction of the information signals. 
   If, as the holder  16  carrying the disc cartridge  120  is lowered so that the disc-shaped recording medium  122  is loaded on the disc table  49 , a recording button (operating button)  4  provided on the outer casing  2  is actuated, so that the driving motor  73  and hence the gear set  74  are run in rotation in one direction. When the gear set  74  is run in rotation, the switching gear  75  is run in rotation, so that the driving gear  76  meshing with the switching gear is run in rotation in one direction, with the consequence that the thrusting boss  76   a  of the g 76  thrusts the thrust edge  71   e  of the operating lever  71  forwards (see  FIG. 54 ). 
   When the thrust edge  71   e  of the operating lever  71  is thrust, since the controlled edge  71   d  is contacted with the support piece  69   e  of the limit lever  69 , positioned at the rear end of the movement stroke, the support piece  69   e  is thrust forwards by the controlled edge  71   d  to cause forward movement of the limit lever  69  (see  FIG. 54 ). When the limit lever  69  is moved forwards, the driving lever  67 , positioned at the forward end of the movement stroke, is moved rearwards by the rotational movement of the conversion lever  70  (see  FIG. 54 ). By the rearward movement of the driving lever  67 , the cam lever  24 , the upper side portion  30   a  of which is engaged in the engagement opening  67   b , is moved towards rear with respect to the holder  16  (see  FIG. 55 ). 
   The limit lever  69 , moved forwards, is moved to the forward end of its movement stroke, as a result of the contact of the support piece  69   e  with the stop edge  6   g  formed on the major surface portion  6 . At this time, the rotation of the driving motor  73  ceases, so that the driving lever  67  is halted at the rear end of its movement stroke (see  FIG. 54 ). When the driving lever  67  is halted at the rear end of its movement stroke, the cam portion  30  of the cam lever  24  has been moved to a point at back of the mating operating piece  23   b  of the head shift lever  23 , such that the head shift lever  23  is held at the lower end of its rotational movement, with the controlling piece  23   a  in contact with the opening edge of the head inserting opening  17   b  of the holder  16 . Consequently, the head mounting arm  58  is inclined so that its forward end is lowered (see  FIG. 55 ). The magnetic head  58   a  is introduced into the holder  16  through the head inserting opening  17   b  into contact with the disc-shaped recording medium  122  through the head access opening  121   a  formed in the casing member  121  of the disc cartridge  120 . One of the rotation controlling pieces  23   a  of the head shift lever  23  is positioned below the retention piece  28  of the cam lever  24  and is retained by the retention piece  28 . 
   With continued driving of the spindle motor, the disc table  49  is run in rotation, while the optical pickup  50  is guided by the guide shafts  53 ,  54 , by the driving of the feed motor  56 , so as to be moved radially of the disc-shaped recording medium  102 . At this time, a laser light beam is illuminated from the objective lens  52   a  of the biaxial actuator  52  of the optical pickup  50  through the through-hole of the casing member  121  to the disc-shaped recording medium  122 , at the same time as a magnetic field is applied through the magnetic head  58   a  to the disc-shaped recording medium  122 , to record information signals. 
   If a stop button (operating button)  4 , among the operating buttons  4 , is actuated, the driving motor  73  is rotated in an opposite direction to that in the previous operation to run the gear set  74  and the switching gear  75  into rotation. The driving gear  76  is run in rotation in a second direction so that the thrust piece  69   f  of the limit lever  69  is thrust rearwards by the thrusting boss  76   a  of the driving gear  76  (see  FIG. 56 ). When the thrust piece  69   f  of the limit lever  69  is thrust, the limit lever  69  and the operating lever  71  are moved rearwards in unison, while the driving lever  67 , located at the rear end of the movement stroke, is moved forwards by the rotational movement of the conversion lever  70  (see  FIG. 56 ). By the forward movement of the driving lever  67 , the cam lever  24 , the upper side portion  30   a  of which is engaged in the engagement opening  67   b , is moved forwards relative to the holder  16 . 
   When the mating operating portion  66   a  of the rotation detection switch  66  is actuated by the operating boss  75   a  of the switching gear  75 , a stop signal is input to the driving motor  73 , so that the operation of the driving motor  73  ceases. The limit lever  69  is halted when it has been moved to the rear end of the movement stroke, while the driving lever  67  is halted at the forward end of its movement stroke (see  FIG. 56 ). The driving gear  76  is reverted to its reference position. 
   When the driving lever  67  is halted at the forward movement stroke end, the mating operating piece  23   b  of the head shift lever  23  is engaged with the second cam portion  29   b  of the cam lever  24 , the magnetic head  58   a  is moved upwards from the head inserting opening  17   b  of the holder  16 , and the magnetic head  58   a  is kept at the second retreat position directly overlying the top plate portion  17  of the holder  16  (see  FIG. 50 ). Simultaneously, the rotation of the disc table  49  is halted to terminate the operation of recording the information signals. 
   When the stop button (operating button)  4  is operated to terminate the reproducing or recording operation, as described above, the driving lever  67  is positioned at the forward movement stroke end, while the limit lever  69  is located at the rear movement stroke end (see  FIG. 56 ) and the joint lever  47  is at the rear movement stroke end (see  FIG. 57 ). 
   If, when the reproducing or recording operation is finished, the ejection button, as one of the operating buttons  4 , is actuated, the driving motor  73  is rotated in the opposite direction. When the driving motor  73  is rotated in the opposite direction, the driving gear  76  is rotated in the second direction, and the mating operating piece  47   b  of the joint lever  47  is thrust forwards, with the joint lever  47  being then moved forwards against the bias of the tension coil spring  48  (see  FIG. 58 ). 
   When the joint lever  47  is moved forwards, the thrust piece  35   c  of the slider  31  is thrust forwards by a thrusting piece  47   c , with the slider  31  being moved forwards (see  FIG. 59 ). When the slider  31  is moved forwards, the support portions  18   a ,  19   a  and the support pins  18   b ,  19   b  of the holder  16  perform relative movement from the lower horizontal portions  37   c ,  38   c  of the cam grooves  37 ,  38  through the inclined portions  37   b ,  38   b  to the upper horizontal portions  37   a ,  38   a  (see  FIG. 43 ). Consequently, since the support pins  18   b ,  19   b  of the holder  16  guided by the guide groove  15   a  formed in the side supporting portions  7 ,  8  of the chassis  5  are elevated, while the disc cartridge  120  held by the holder  16  is elevated along with the holder  16 , the disc-shaped recording medium  122  is unloaded from the disc table  49 . 
   When the holder  16  is elevated with the forward movement of the slider  31 , the cam lever  24 , the upper side portion  30   a  of which has been engaged in the engagement opening  67   b  of the of the driving lever  67 , has the lower side portion  30   c  engaged in the engagement opening  67   b . The cam lever  24  is moved forwards relative to the holder  16  a distance equal to the distance between the upper side portion  30   a  and the lower side portion  30   c  in the fore-and-aft direction. Consequently, the head shift lever  23  has the mating operating piece  23   b  engaged in the first cam portion  29   a  of the cam lever  24 , with the head mounting arm  58  being substantially in the horizontal position (see  FIG. 46 ). With forward movement of the slider  31 , the spring member  45  is extended to increase the biasing force of the ejection lever  39  in the direction indicated by arrow R 1  in  FIG. 46 . When the ejection lever  39  is rotated clockwise, as the roll  44  rolls on the inclined edge  33   d  of the slider  31 , and the control edge  41   a  is spaced apart from the controlled piece  33   c , the ejection lever  39  is rotated significantly clockwise under the force of the spring member  45 , such that the ejection lever  39  is rotated in the direction indicated by arrow R 1  in  FIG. 60  until the insertion piece  42   b  is brought into contact with the forward opening edge of the control opening  10   c  of the lever supporting portion  9  provided to the chassis  5 . At this time, the holder  16  has been rotated to the insertion/ejection position. When the ejection lever  39  is rotated in the direction indicated by arrow R 1  in  FIG. 60 , the casing member  21  of the disc cartridge  120  is thrust forwards by the operating portion  43 , so that a portion of the disc cartridge  100  is ejected from the holder  16 . 
   When the disc cartridge  120  is ejected from the holder  16 , the holder  21   a  of the shutter restoration spring  21  is engaged in the engagement opening  123   a  of the shutter  123 , so that the shutter  123  is slid to stop up the through-hole and the head access opening  121   a  formed in the casing member  121 . The through-hole and the head access opening  121   a  are closed. 
   The driving gear  76  continues to be rotated and the thrusting boss  76   a  is disengaged from the mating operating piece  47   b  of the joint lever  47  into engagement with the mating operating edge  71   c  of the operating lever  71  (see  FIG. 61 ). Since the mating operating piece  47   b  of the joint lever  47  is disengaged from the thrusting boss  76   a , the joint lever  47  is moved to the rear movement stroke end under the bias of the tension coil spring  48  (see  FIG. 62 ). 
   When the thrusting boss  76   a  of the driving gear  76  is engaged with the operated edge  71   c  of the operating lever  71 , the operating lever  71  is rotated, with rotation of the driving gear  76 , against the bias of the tension spring  72 , such that the thrusting boss  76   a  is bought into sliding contact with the mating operating edge  71   c  (see  FIG. 61 ). 
   As the driving gear  76  further continues its rotation, the thrusting boss  76   a  is disengaged from the mating operating edge  71   c  of the operating lever  71 . The operating lever  71  is rotated under the bias of the tension spring  72  to return to a state in which the controlled edge  71   d  is contacted with the support piece  69   e  of the limit lever  69  (see  FIG. 63 ). The switching gear  75  is also run in rotation by rotation of the driving motor  73 . When the operating boss  75   a  acts on the mating operating portion  66   a  of the rotation detection switch  66 , a stop signal is input to the driving motor  73  to stop the rotation of the driving motor  73  (see  FIG. 63 ). The driving gear  76  is returned to its reference position. 
   The disc cartridge  120 , ejected from the holder  16 , is partially protruded via the insertion/ejection opening  2   a  of the outer casing  2 . The protruded portion may be gripped and extracted to take out the disc cartridge  120 . 
   When taking out the disc cartridge  120 , the unlock piece  22  provided on the side plate portion  19  of the holder  16  is moved rearwards in the groove  101   b  of the disc cartridge  120  by relative movement. The shutter  123  is again locked by a lock mechanism. 
   With the disc recording and/or reproducing apparatus  1  of the present invention, described above, the driving gear  76 , run in rotation by the driving power transmitted from the driving motor  73 , is rotated in the first direction to lower the magnetic head  58   a  to set up a state enabling the recording operation of information signals. The driving gear  76  is run in rotation in the second direction opposite to the first direction to perform the ejecting operation of the disc cartridge  120 . Thus, when both the head movement mechanism and the ejection mechanism are operated by the driving motor  73 , there is no necessity of continuously moving one of the driving lever  67  and the joint lever  47  in the same direction to actuate the head movement mechanism and the ejection mechanism, the movement stroke of the driving lever  67  and that of the joint lever  47  may be correspondingly reduced to enable the size of the disc recording and/or reproducing apparatus to be reduced. 
   The disc recording and/or reproducing apparatus  1  of the present invention is provided with the operating lever  71  which operates the limit lever  69 , using the thrusting boss  76   a  operating as the driving power transmitting portion, when the driving motor  73  is rotated in one direction, and which is receded from the trajectory of the thrusting boss  76   a  when the driving motor  73  is rotated in the other direction. Consequently, the operating lever  71  does not obstruct rotation of the driving gear  76  when the driving motor  73  is rotated in the opposite direction to actuate the ejection mechanism, so that the operation of the disc recording and/or reproducing apparatus  1  may be optimum. 
   In addition, with the disc recording and/or reproducing apparatus  1 , since there is provided the rotation detection switch  66  which detects the end of the operation of the ejection mechanism and the end of the operation of the head movement mechanism, it is unnecessary to provide a dedicated switch detecting the state of completion of the operation, from one mechanism to another, thus enabling the number of component parts to be reduced. 
   The manual ejection operation for the disc cartridge  120  is now explained. The manual ejection operation in the disc recording and/or reproducing apparatus  1  may be classed into an ejection operation in the stop mode in which the recording or reproduction for the disc-shaped recording medium  122  has come to a close, an ejection operation in the replay mode and an ejection operation in the recording mode. It is when for example the driving motor  73  has ceased its operation due to battery down that the manual ejection operation is needed. 
   In the operation in any of these three modes, the joint lever  47  is moved forwards by manual operation to eject the disc cartridge  120 . The forward movement of the joint lever  47  may be achieved by for example inserting a pin into an insertion opening, not shown, formed in the back side of the outer casing  2 , to thrust the thrusting portion  47   e  from rear side. 
   First, the operation of the manual ejection operation in the stop and replay modes and the ejecting operation during reproduction for the disc-shaped recording medium  122  are explained. These two operations are accomplished by moving the joint lever  47  forwards as the mating operating piece  23   b  of the head shift lever  23  is engaged in the second cam portion  29   b  of the cam lever  24 , as shown in  FIG. 44 . 
   When the joint lever  47  is moved forwards, the thrust piece  35   c  of the slider  31  is thrust forwards by the thrusting piece  47   c , such that the support portions  18   a ,  19   a  and the support pins  18   b ,  19   b  of the holder  16  perform relative movement from the lower horizontal portions  37   c ,  38   c  of the cam grooves  37 ,  38  through the inclined portions  37   b ,  38   b  to the upper horizontal portions  37   a ,  38   a  (see  FIG. 43 ). Consequently, the holder  16  is elevated to unload the disc-shaped recording medium  122  from the disc table  49 . 
   When the holder  16  is elevated, the lower side portion  30   c  of the cam lever  24  is engaged in the engagement opening  67   b , such that the cam lever  24  is moved forwards relative to the holder  16  by a distance corresponding to the distance between the upper side portion  30   a  and the lower side portion  30   c  in the fore-and-aft direction. Thus, the head shift lever  23 , the mating operating piece  23   b  of which has been engaged in the second cam portion  29   b  of the cam lever  24 , now has the mating operating piece  23   b  engaged in the first cam portion  29   b  of the cam lever  24 , with the head mounting arm  58  then being in substantially the horizontal position (see  FIG. 46 ). 
   As the slider  31  is moved forwards, the spring member  45  is extended. When the control edge  41   a  is separated from the controlled piece  33   c , the ejection lever  39  is rotated appreciably in the direction indicated by arrow R 1 , under the force of the spring member  45 . The casing member  121  of the disc cartridge  100  is thrust forwards significantly by the operating portion  43  to eject the disc cartridge  120  from the holder  16  (see  FIG. 60 ). 
   The disc cartridge  120 , ejected from the holder  16 , is partially protruded via the insertion/ejection opening  2   a  of the outer casing  2 . The protruded portion may be gripped and extracted to take out the disc cartridge  120 . 
   The operation of manual ejection in the recording mode is now explained. This operation is carried out by causing forward movement of the joint lever  47 , as the mating operating piece  23   b  of the head shift lever  23  is located ahead of the cam portion  30  of the cam lever  24 , as shown in  FIG. 55 . When the joint lever  47  is moved forwards, the thrust piece  35   c  of the slider  31  is thrust forwards, by the thrusting piece  47   c , so that the support portions  18   a ,  19   a  and the support pins  18   b ,  19   b  of the holder  16  perform relative movement from the lower horizontal portions  37   c ,  38   c  of the cam grooves  37 ,  38  through the inclined portions  37   b ,  38   b  to the upper horizontal portions  37   a ,  38   a  (see  FIG. 43 ). Consequently, the holder  16  is elevated to unload the disc-shaped recording medium  122  from the disc table  49 . 
   When the holder  16  is elevated, the lower side portion  30   c  of the cam lever  24  is engaged in the engagement opening  67   b , such that the cam lever  24  is moved forwards relative to the holder  16  by a distance corresponding to the distance between the upper side portion  30   a  and the lower side portion  30   c  in the fore-and-aft direction. Thus, the head shift lever  23 , the mating operating piece  23   b  of which has been engaged in the second cam portion  29   b  of the cam lever  24 , now has the mating operating piece  23   b  engaged in the third cam portion  29   c  of the cam lever  24 , with the head mounting arm  58  then being in substantially the horizontal state (see  FIG. 64 ). As the head mounting arm  58  is at substantially the horizontal position, the magnetic head  58   a  is uplifted from the head inserting opening  17   b  of the holder  16 . The magnetic head  58   a  is moved upwards from the head inserting opening  17   b  of the holder  16  and is held at a third retreat position directly overlying the top plate portion  17  of the holder  16 . The disc cartridge  120  may now be ejectable without contacting with the magnetic head  58   a  (see  FIG. 64 ). This third retreat position, as the relative position of the holder  16  with respect to the top plate portion  17 , is substantially the same as the first and second retreat positions described above. With forward movement of the slider  31 , the spring member  45  is extended. When the control edge  41   a  is separated from the controlled piece  33   c , the ejection lever  39  is rotated appreciably in the direction indicated by arrow R 1 , under the spring force of the spring member  45 . The casing member  121  of the disc cartridge  120  is thrust forwards by the operating portion  43  to eject the disc cartridge  120  from the holder  16  (see  FIG. 60 ). The disc cartridge  120  ejected from the holder  16  is partially protruded from the insertion/ejection opening  2   a  of the outer casing  2 , so that the disc cartridge  120  can be taken out by gripping and pulling the protruded portion outwards. 
   Thus, in the recording mode, the cam lever  24  is moved forwards to retreat the magnetic head  58   a  to above the disc cartridge  120  being ejected and to hold the magnetic head  58   a  at the third retreat position to achieve the ejecting operation without damaging the magnetic head  58   a.    
   With the disc recording and/or reproducing apparatus  1 , according to the present invention, the magnetic head  58   a  is held at the first, second or third retreat position, for which the position relationships of the holder to the top plate portion  17  are substantially the same, except during the recording operation, when the disc cartridge  120  is held on the holder  16 . Consequently, the spacing of movement of the magnetic head  58   a  between the upper surface of the outer casing  2  and the top plate portion  17  can be minimized to allow to reduce the thickness of the disc recording and/or reproducing apparatus  1 . 
   Moreover, with the disc recording and/or reproducing apparatus  1 , according to the present invention, the cam lever  24  is provided with the inclined portion  30   b  slidably engaged in the engagement opening  67   b  of the driving lever  67  and, when the cam lever  24  is uplifted or lowered with the uplifting or descent of the holder  16 , the engaging position of the inclined portion  30   b  in the engagement opening  67   b  is changed to cause the cam lever  24  to be moved in the fore-and-aft direction with respect to the holder  16 . Thus, it is sufficient to provide the inclined portion  30   b  for causing movement of the cam lever  24  relative to the holder  16  to simplify the structure or mechanism for ejection to realize positive ejection without increasing the cost. 
   In the disc recording and/or reproducing apparatus  1  according to the present invention, the recording head used is the magnetic head  58   a . This, however, is merely illustrative, and any of recording heads consistent with the recording system for a recording medium, such as an optical head or a magneto-optical disc, may be used as the recording head. 
   The shape or structure of the various components, indicated in the above-described embodiments, are given only byway of examples in practicing the invention, and should not be construed in the sense of limiting the present invention. 
   INDUSTRIAL APPLICABILITY 
   With the disc recording and/or reproducing apparatus according to the present invention, in which the spring member is provided between the ejection lever and the slider and the ejection lever is biased by this spring member in a direction of ejecting the recording medium from the holder, and in which the slider is also biased in the direction of introducing the recording medium, the mechanism of ejecting the recording medium may be simplified to reduce the number of component parts of the overall apparatus. 
   Moreover, with the disc recording and/or reproducing apparatus according to the present invention, in which the relative positions of the head, contacted with and separated away from the recording medium, and the holder, with respect to the contacting or separating direction, is substantially constant for the first retreat position receded from the recording medium held by the holder, the second retreat position receded from the recording medium during reproduction of the information signals and for the third retreat position receded from the recording medium being ejected from the holder, the spacing of movement of the magnetic head between the outer casing and the holder may be minimized to reduce the thickness of the overall apparatus. 
   In addition, with the disc recording and/or reproducing apparatus according to the present invention, in which the ejection mechanism or the head movement mechanism is operated depending on the direction of rotation of the driving gear, rotated in one or the opposite direction by the driving motor, the ejection mechanism and the head movement mechanism can be simplified to reduce the size of the apparatus. 
   Furthermore, with the disc recording and/or reproducing apparatus according to the present invention, in which, when the disc housed in the disc cartridge is loaded on the disc table, the shutter provided on the disc cartridge opened by the shutter opening/closing mechanism is retained by the retention mechanism, the shutter may undergo vibrations during the disc reproducing or recording operation only to a lesser extent for assuring stabilized recording and/or reproduction of information signals.