Patent Publication Number: US-6988838-B2

Title: Ink jet recording apparatus

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to an ink jet recording apparatus which is capable of printing an optical recording medium and a magnetic recording medium. More particularly, the invention relates to an ink jet recording apparatus which enables an operator to perform all of necessary operations from a specific one direction. 
   Recently, the ink jet recording apparatus (printer) comes to be connected not only to the computer but also to another devices, such as a television or VTR. The device installing location is also changing from a desk top to a location at which some or many persons come together, such as a living room. A recording device is proposed which is designed such that in consideration of stacking the recording device on other device, an operator may load and unload the ink cartridge, set recording sheets, and take out the recording sheets as set, from the front side of the recording device. A printer disclosed in JP-A-2001-191613, for example, is known for an example of such a recording device. 
   A digital information distributing system which directly prints on a portable data media, such as CDROM, is disclosed in JP-A-2001-319074. 
   In the case of those conventional recording devices, however, it is impossible to print on both a data media, such as a CD or a DVD, and a normal sheet (recording sheet). 
   An ink jet recording apparatus which is capable of printing on both a data media, such as a CD or a DVD and a normal sheet (recording sheet), is disclosed in JP-A-2002-127526. The ink jet recording apparatus is arranged such that an optical disc tray is inserted into the device through a sheet supplying port, and a paper delivery serration is separated from the discharge roller. Therefore, the operator needs additional work to insert the optical disc tray into the recording device through the sheet supplying port. Further, apart of the optical disc tray protrudes to outside the ink jet recording apparatus. Accordingly, space to install the ink jet recording apparatus is increased by an amount corresponding to the projection. 
   SUMMARY OF THE INVENTION 
   Accordingly, an object of the invention is to provide an ink jet recording apparatus which is compactly accommodated in, for example, a television rack in a home and in this state, is capable of printing on a normal paper or a thing other than the normal paper. 
   According to first aspect of the invention, there is provided an ink jet recording apparatus comprising: a medium holding plate which is contained in the ink jet recording apparatus and on which a first recording medium is to be placed; a select switch for switching a protruding state of the medium holding plate out of the ink jet recording apparatus and an accommodating state of the medium holding plate; a medium tray which is contained in the ink jet recording apparatus and on which a second recording medium is to be placed, the medium tray being substantially parallel to the medium holding plate; a first transporting system for reciprocatively moving the medium holding plate in a first direction and a second direction opposite to the first direction; a second transporting system for transporting the second recording medium in the first direction; and a recording head for ejecting ink to the first recording medium on the medium holding plate which is transported in the first direction by the first transporting system, and the second recording medium on the medium holding plate which is transported in the second direction by the second transporting system; wherein the select switch, the medium tray, and the medium holding plate are operated on the front side of the ink jet recording apparatus. 
   The first transporting system and the second transporting system may include each at least one transporting roller. 
   The first transporting system may include a motor, a pinion driven by the motor, and a gear which is provided on the medium holding plate so as to be in mesh with the pinion. 
   Preferably, the second transporting system includes a feed roller for transporting exclusively the second recording medium, and free rollers, in transporting the medium holding plate, the feed roller and the free roller ascend to be not in contact with the medium holding plate, and in transporting the second recording medium, the feed roller and the free roller descend to be in contact with the second recording medium. 
   Preferably, the first transporting system and the second transporting system include each a pinch roller provided opposite to the transporting roller, and when the medium holding plate is transported to the first direction, and when a leading end of the medium holding plate as viewed in the transporting direction passes between the transporting roller and the pinch roller, a distance between the transporting roller and the pinch roller is larger than a thickness of the medium holding plate. 
   It is preferable that a distance between the first recording medium and the recording head and a distance between the second recording medium and the recording head are kept constant. 
   The medium holding plate and the medium tray may be completely accommodated in the ink jet recording apparatus at least when the recording head starts to print. 
   The first recording medium may include at least one of an optical recording medium, a magnetic recording medium, an electronic recording medium, a plastic card, a resin solid material, and a metal solid material. 
   According to second aspect of the invention, there is provided an ink jet recording device having a medium holding plate on which an optical recording medium is to be placed, a transporting system for transporting the medium holding plate in a first direction, and a recording head for ejecting ink toward the optical recording medium on the medium holding plate, which is transported in the first direction by the transporting system, the improvement being characterized in that the medium holding plate is provided so as to be movable in a second direction which is different from the first direction, and when the optical recording medium is loaded into or unloaded from the ink jet recording device, the medium holding plate moves along the second direction to outside the ink jet recording device. 
   Thus, the medium holding plate on which the optical recording medium is to be placed may be transported in two directions, a first direction and a second direction. The medium holding plate is accommodated in the ink jet recording device at the time of printing on the optical recording medium. Accordingly, the ink jet recording device may compactly be accommodated in, for example, a television rack in a home. 
   When the recording head prints on the optical recording medium, the medium holding plate which is contained in the ink jet recording device is transported in the first direction. When the optical recording medium is loaded into or unloaded from the ink jet recording device, the medium holding plate moves along the second direction to outside the ink jet recording device. 
   The ink jet recording device may further include: a motor for driving and moving the medium holding plate in the first direction; a first region in which the motor drives and moves the medium holding plate in the first direction; and a second region in which the transporting system drives and transports the medium holding plate in the first direction. 
   The ink jet recording device may further include a motor for driving and moving the medium holding plate in the second direction. With this feature, it is easy to load the optical recording medium into and unload it from the ink jet recording device. 
   The transporting system may include a pinch roller for transporting the medium holding plate in the first direction, and the ink jet recording device may include a pinch-roller distance changing mechanism which automatically changes a distance as viewed in thickness direction of the medium holding plate between the pinch roller and the medium holding plate in accordance with at least one of a thickness and a kind of the medium holding plate. With this feature, even if the thickness and the kind of the medium holding plate change, there is no need that the operator performs an adjusting work. 
   According to third aspect of the invention, there is provided an ink jet recording device having a medium holding plate on which an optical recording medium is to be placed, a medium supplying part for supplying a second recording medium, a pinch roller and a main roller, which form a first transporting system for transporting the medium holding plate, a pinch roller and a main roller, which form a second transporting system for transporting the second recording medium from the medium supplying part, and a recording head for ejecting ink to the first recording medium and the second recording medium on the medium holding plate, which is transported in a first direction by the first transporting system and the second transporting system, the improvement being characterized in that the medium holding plate is provided so as to be movable in a second direction which is different from the first direction, the medium holding plate moves along the second direction to outside the ink jet recording device only when the first recording medium may be loaded to or unloaded from the ink jet recording device, and the medium holding plate is accommodated in the ink jet recording device when the first recording medium may be loaded into or unloaded from the ink jet recording device. 
   Preferably, the medium supplying part is movable in the second direction. 
   Preferably, the medium holding plate is provided above the medium supplying part, and a recording sheet as the second recording medium on which the recording head prints is discharged into between the medium holding plate and the medium supplying part. In this case, the medium holding plate, the medium supplying part and a space to which the second recording medium is discharged are efficiently disposed. 
   Preferably, the ink jet recording device further includes: a motor for driving and moving the medium holding plate in the first direction; a first region in which the motor drives and moves the medium holding plate in the first direction; and a second region in which the transporting system drives and transports the medium holding plate in the first direction. 
   If the first region and the second region are disposed so as to partially overlap with each other, a drive by the motor partially overlaps with a drive by the first transporting system. 
   Preferably, the first transporting system and the second transporting system use a pinch roller for transporting the medium holding plate and the second recording medium in a first direction, and the ink jet recording device includes a pinch-roller distance changing mechanism which automatically changes a distance as viewed in thickness direction of the medium holding plate between the pinch roller and the medium holding plate in accordance with at least one of a thickness and a kind of the medium holding plate and/or the second recording medium. 
   When the medium holding plate is transported by the first transporting system and the recording sheet as the second recording medium is transported by the second transporting system, the pinch roller is commonly used, with a distance as viewed in thickness direction of the medium holding plate between the pinch roller and the medium holding plate, which is changed by the pinch-roller distance changing mechanism. 
   The ink jet recording device may further include a discharge tray into which the second recording medium on which the recording head prints is discharged, wherein a disc tray as the medium holding plate, a sheet feed cassette as the medium supplying part and the discharge tray are disposed substantially parallel to one another. 
   With such a construction, the printed recording sheet is discharged into the discharge tray disposed between the disc tray and the sheet feed cassette, while being parallel to the latter. 
   In the ink jet recording device, a tray guide as a guide part for guiding the medium holding plate is formed on the discharge tray, when the medium holding plate moves in the second direction, the medium holding plate is held by the tray guide, and when the medium holding plate moves in the first direction, the medium holding plate is moved relative to the tray guide. 
   According to fourth aspect of the invention, there is provided an ink jet recording apparatus comprising: a first transpoting system for reciprocatively transporting along a first direction a medium holding plate on which a first recording medium is to be placed; a medium tray on which a second recording medium is to be placed, the medium tray being substantially parallel to the medium holding plate; a loading mechanism for transporting the medium holding plate in a second direction perpendicular to the first direction and for switching between a protruding state and an accommodated state of the disc tray on the front side of the ink jet recording apparatus; and a discharge tray, provided substantially parallel to the medium tray, for accommodating the second recording medium which has received ink ejected from the recording head; wherein the medium tray, the discharge tray, and the medium holding plate are operated on the front side of the ink jet recording apparatus. 
   Thus, the medium holding plate on which the first recording medium is to be placed may be transported in two directions, a first direction and a second direction. Therefore, the ink jet recording apparatus is reduced in size in the first direction, and it is compactly accommodated in, for example, a television rack in a home. 
   The medium tray, the discharge tray, and the medium holding plate are all operated on the front side of the ink jet recording apparatus. A loading mechanism for switching between a protruding state and an accommodated state of the disc tray on the front side of the ink jet recording apparatus is provided. Therefore, the ink jet recording apparatus may be accommodated in a place having an opening only at the front, such as a television rack in a home. 
   Further, the medium tray and the medium holding plate are disposed substantially parallel to each other. Therefore, the ink jet recording apparatus is reduced in height. The ink jet recording apparatus may compactly be accommodated in, for example, a television rack in a home. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view showing an external appearance of an ink jet recording apparatus in an embodiment of the invention. 
       FIG. 2  is a perspective view showing an external appearance of the ink jet recording apparatus in the embodiment of the invention when the disc tray is at a loading/unloading position. 
       FIG. 3  is a perspective view showing an external appearance of the ink jet recording apparatus in the embodiment of the invention when the sheet feed tray is drawn out. 
       FIG. 4  is a perspective view showing a key portion of the ink jet recording apparatus in the embodiment of the invention. 
       FIG. 5  is a top view showing the innards of the ink jet recording apparatus in the embodiment of the invention when the disc tray is at a print ready position. 
       FIG. 6  is a cross sectional view taken on line A—A in FIG.  5 . 
       FIG. 7  is a cross sectional view taken on line F—F in FIG.  5 . 
       FIG. 8  is a partially enlarged view showing a structural relationship among the tray guide, the disc tray and the DVD disc in the ink jet recording apparatus in the embodiment of the invention. 
       FIG. 9  is an enlarged view of a key portion of the innards of the ink jet recording apparatus in the embodiment of the invention when the disc tray is at the print ready position. 
       FIG. 10  is an enlarged view showing a key portion of the innards of the ink jet recording apparatus of the embodiment of the invention when an operation step is ST 3 . 
       FIG. 11  is an enlarged view showing a key portion of the innards of the ink jet recording apparatus of the embodiment of the invention when an operation step is ST 4 . 
       FIG. 12  is an enlarged view showing a key portion of the innards of the ink jet recording apparatus of the embodiment of the invention when an operation step is ST 6 . 
       FIG. 13  is an enlarged view showing a key portion of the innards of the ink jet recording apparatus of the embodiment of the invention when an operation step is ST 7 . 
       FIG. 14  is an enlarged view showing a key portion of the innards of the ink jet recording apparatus of the embodiment of the invention when an operation step is ST 8 . 
       FIG. 15  is an enlarged view showing the innards of the ink jet recording apparatus of the embodiment of the invention when an operation step is ST 7 . 
       FIG. 16  is a cross sectional view taken on line B—B in FIG.  15 . 
       FIG. 17  is a top view showing the innards of the ink jet recording apparatus in the embodiment of the invention when the disc tray is at a loading/unloading position. 
       FIG. 18  is a cross sectional view taken on line C—C in FIG.  17 . 
       FIG. 19  is a top view showing the innards of the ink jet recording apparatus in the embodiment of the invention when the disc tray is at a print start position (ST  11 ). 
       FIG. 20  is a cross sectional view taken on line D—D in FIG.  19 . 
       FIG. 21  is an enlarged view showing a key portion of the innards of the ink jet recording apparatus of the embodiment of the invention when an operation step is ST  22 . 
       FIG. 22  is a top view showing the ink jet recording apparatus in the embodiment of the invention when the recording device is in a sheet supplying mode. 
       FIG. 23  is a cross sectional view taken on line E—E in FIG.  22 . 
       FIG. 24  is a flow chart showing operations of the ink jet recording apparatus in the embodiment of the invention. 
       FIG. 25  is a side view conceptually showing an exemplary application of an ink jet recording device as an embodiment of the invention when it is installed in a home-use television rack. 
       FIG. 26  is a perspective view showing an external appearance of an ink jet recording device as a second embodiment of the invention. 
       FIG. 27  is a perspective view showing an external appearance of the ink jet recording device when a discharge tray is in a discharge-tray open position. 
       FIG. 28  is a perspective view showing an external appearance of the ink jet recording device when the discharge tray is in a discharge-tray maximum drawn-out position. 
       FIG. 29  is a perspective view showing an external appearance of the ink jet recording device in a state that a tray guide is pulled up in order to take out a discharged sheet at the discharge-tray maximum drawn-out position. 
       FIG. 30  is a perspective view showing a key portion of the ink jet recording device as the second embodiment of the invention. 
       FIG. 31  is a top view showing the innards of the ink jet recording device at a print ready position in the second embodiment of the invention. 
       FIG. 32  is a cross sectional view taken on line A—A in FIG.  31 . 
       FIG. 33A  is a top view showing the innards of the ink jet recording device at a discharge-tray open position in the second embodiment of the invention. 
       FIG. 33B  is a top view showing a modification of the second embodiment of the invention shown in FIG.  33 A. 
       FIG. 34  is a top view showing the innards of the ink jet recording device at a discharge-tray maximum drawn-out position in the second embodiment of the invention. 
       FIG. 35  is a top view showing the innards of the ink jet recording device at a disc tray pull-in position in the second embodiment of the invention. 
       FIG. 36  is a cross sectional view taken on line A—A in FIG.  35 . 
       FIG. 37  is a top view showing the innards of the ink jet recording device at a print start position in the second embodiment of the invention. 
       FIG. 38  is a cross sectional view taken line A—A in FIG.  37 . 
       FIG. 39  is a top view showing the innards of the ink jet recording device at a print end position in the second embodiment of the invention. 
       FIG. 40  is a cross sectional view taken line A—A in FIG.  39 . 
       FIG. 41  is a perspective view showing an external appearance showing the ink jet recording device in the second embodiment of the invention when a sheet feed cassette is drawn out. 
       FIG. 42  is a partially enlarged view showing a structural relationship among the tray guide, a disc tray and a DVD disc in the ink jet recording device. 
       FIG. 43  is a conceptual diagram showing a key portion of a moving mechanism (pinch-roller distance changing mechanism) including a carriage, a pinch roller, and free gears. 
       FIG. 44  is a conceptual diagram showing a key portion of a moving mechanism (pinch-roller distance changing mechanism) including a carriage, a pinch roller, and free gears in the second embodiment of the invention when the discharge tray is at a disc tray pull-in position. 
       FIG. 45  is a conceptual diagram showing a key portion of a moving mechanism (pinch-roller distance changing mechanism) including a carriage, a pinch roller, and free gears in the second embodiment of the invention when the ink jet recording device is during printing. 
       FIG. 46  is a flow chart for explaining operations of the ink jet recording device in the second embodiment of the invention. 
       FIG. 47  is an enlarged, conceptual diagram showing a key portion of a pinch-roller distance changing mechanism in the second embodiment of the invention when the discharge tray is at a normal sheet printing position. 
       FIG. 48  is an enlarged, conceptual diagram showing a key portion of the pinch-roller distance changing mechanism when the recording head and the free rollers ascend to the disc print position in FIG.  47 . 
       FIG. 49  is an enlarged, conceptual diagram showing a key portion of the pinch-roller distance changing mechanism when the pinch roller ascends to the disc tray pull-in position in FIG.  48 . 
       FIG. 50  is an enlarged, conceptual diagram showing a key portion of the pinch-roller distance changing mechanism when the leading end of the discharge tray passes under the pinch roller in FIG.  49 . 
       FIG. 51  is an enlarged, conceptual diagram showing a key portion of the pinch-roller distance changing mechanism when the pinch roller descends in FIG.  50 . 
       FIG. 52  is an enlarged, conceptual diagram showing a key portion of the pinch-roller distance changing mechanism when the discharge tray is transported to the print start position in FIG.  51 . 
       FIG. 53  is an enlarged, conceptual diagram showing a key portion of the pinch-roller distance changing mechanism during the printing on the disc in FIG.  52 . 
       FIG. 54  is an enlarged, conceptual diagram showing a key portion of the pinch-roller distance changing mechanism when the operation of printing on the disc is completed in FIG.  53 . 
       FIG. 55  is a flow chart for explaining operations of a first modification of the second embodiment of the invention. 
       FIG. 56  is a flow chart for explaining operations of a second modification of the second embodiment of the invention. 
       FIG. 57  is a perspective view showing a key portion of the innards of the ink jet recording device at the print ready position in the third embodiment of the invention. 
       FIG. 58  is an enlarged, perspective view showing an auxiliary roller and a tray transporting roller in the third embodiment of the invention. 
       FIG. 59  is a top view showing the innards of the ink jet recording device at the print ready position in the third embodiment of the invention. 
       FIG. 60  is a cross sectional view taken on line B—B in FIG.  59 . 
       FIG. 61  is a cross sectional view taken on line A—A in FIG.  59 . 
       FIG. 62  is a top view showing the innards of the ink jet recording device at a disc loading/unloading position in the third embodiment of the invention. 
       FIG. 63  is a cross sectional view taken on line A—A in FIG.  62 . 
       FIG. 64  is a top view showing the innards of the ink jet recording device at the disc pull-in start position in the third embodiment. 
       FIG. 65  is a cross sectional view taken on line B—B in FIG.  64 . 
       FIG. 66  is a cross sectional view taken on line A—A in FIG.  64 . 
       FIG. 67  is a top view showing the innards of the ink jet recording device at the print start position in the third embodiment. 
       FIG. 68  is a cross sectional view taken on line B—B in FIG.  67 . 
       FIG. 69  is a cross sectional view taken on line A—A in  FIG. 67   
       FIG. 70  is a top view showing the innards of the ink jet recording device at the print end position in the third embodiment. 
       FIG. 71  is a cross sectional view taken on line B—B in FIG.  70 . 
       FIG. 72  is a cross sectional view taken on line A—A in FIG.  70 . 
       FIG. 73  is a flow chart showing operations of the ink jet recording device in the third embodiment of the invention. 
       FIG. 74  is a perspective view showing a major portion of an ink jet recording device in a fourth embodiment of the invention. 
       FIG. 75  is a perspective view showing a key portion of the innards of the ink jet recording device shown in  FIG. 74  in which a tray-guide support plate is additionally illustrated. 
       FIG. 76  is a top view showing a discharge tray in the fourth embodiment of the invention. 
       FIG. 77  is a top view showing a tray guide in the fourth embodiment of the invention. 
       FIG. 78  is a side view showing the structure shown in FIG.  77 . 
       FIG. 79  is a top view showing the structure shown in FIG.  77 . 
       FIG. 80  is a cross sectional view taken on line F—F in FIG.  77 . 
       FIG. 81  is a partial top view showing, in model form, movements of the tray guide and the disc tray when those move from the disc loading/unloading position to the print ready position in the fourth embodiment of the invention. 
       FIG. 82  is a partially enlarged view showing a relationship between the pinion and the gear. 
       FIG. 83  is a partial top view showing, in model form, a state that the tray guide and the disc tray have further been moved from a position shown in  FIG. 81  to the print ready position in the fourth embodiment of the invention 
       FIG. 84  is a partially enlarged view showing a relationship between the pinion and the gear in FIG.  83 . 
       FIG. 85  is a partial top view showing, in model form, a state of the tray guide and the disc tray when those are at the print ready position in the fourth embodiment of the invention. 
       FIG. 86  is a partially enlarged view showing a relationship between the pinion and the gear in FIG.  85 . 
       FIG. 87  is a partial top view showing disc feeding rollers in the fourth embodiment of the invention. 
       FIG. 88  is a conceptual diagram showing positions of the disc feeding rollers and the free rollers in a normal sheet printing mode in the fourth embodiment of the invention. 
       FIG. 89  is a conceptual diagram showing positions of the disc feeding rollers and the free rollers in a disc pull-in start position in the fourth embodiment of the invention. 
       FIG. 90  is a top view showing the innards of the ink jet recording device at the print ready position in the fourth embodiment of the invention. 
       FIG. 91  is a cross sectional view taken line A—A in FIG.  90 . 
       FIG. 92  is a top view showing the innards of the recording device shown in  FIG. 90  in which a tray-guide support plate is omitted. 
       FIG. 93  is a cross sectional view taken on line A—A in FIG.  92 . 
       FIG. 94  is a top view showing the innards of the ink jet recording device at the disc loading/unloading position in the fourth embodiment of the invention. 
       FIG. 95  is a cross sectional view taken on line A—A in FIG.  94 . 
       FIG. 96  is a top view showing the innards of the recording device shown in  FIG. 94  in which a tray-guide support plate is omitted. 
       FIG. 97  is a cross sectional view taken on line A—A in FIG.  96 . 
       FIG. 98  is a top view showing the innards of the ink jet recording device at the disc pull-in start position in the fourth embodiment of the invention. 
       FIG. 99  is a cross sectional view taken on line A—A in FIG.  98 . 
       FIG. 100  is a top view showing the innards of the ink jet recording device at the print start position in the fourth embodiment of the invention. 
       FIG. 101  is a cross sectional view taken on line A—A in FIG.  100 . 
       FIG. 102  is a top view showing the innards of the ink jet recording device at the print end position in the fourth embodiment of the invention. 
       FIG. 103  is a cross sectional view taken on line A—A in FIG.  102 . 
       FIG. 104  is a flow chart for explaining operations of the ink jet recording device in the second embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The preferred embodiments of the present invention will be described with reference to the accompanying drawings. In those drawings, like or equivalent portions will be designated by like reference numerals, for simplicity. 
   [First Embodiment] 
     FIG. 1  is a perspective view showing an external appearance of an ink jet recording apparatus  301  which is an embodiment of the invention in a state that a sheet feed tray  303  and a disc tray  307  are accommodated in the recording device.  FIG. 2  is a perspective view showing an external appearance of the ink jet recording apparatus  1  in a state that the disc tray  307  is protruded to outside the recording device (A position of the disc tray in this state will be referred to as a loading/unloading position).  FIG. 3  is a perspective view showing an external appearance of the ink jet recording apparatus  1  in a state that a sheet feed tray  303  having a recording sheet  313  put thereon is drawn out to the full extent (A position of the sheet feed tray in this state will be referred to as “sheet-feed-tray maximum drawn-out position”, hereinafter).  FIG. 4  is a perspective view showing a key portion of the ink jet recording apparatus  301 . 
   Referring to  FIGS. 1 through 3 , a main operation panel (front side) of an ink jet recording apparatus  301  contains a power switch  302 , an ink exchange button  304 , a sheet-kind setting button  305 , a reset button  306 , a disc loading switch  308  as a select switch for switching between a protruding state and an accommodated state of the disc tray  307 , a memory card slot  310 , indicator lamps  312  and  314  for indicating statuses of buttons  304  and  305 , a remote control light receiving part  316 , and an ink-cartridge replacing cover  318 . 
   A tray guide  311  shown in  FIG. 4  is integral with a housing of the ink jet recording apparatus  301 , and guides a disc tray  307  as a medium holding plate. 
   As shown in  FIG. 7 , the disc tray  307  is held within the tray guide  311 , and the sheet feed tray  303  is held by a sheet feed tray guide  400 . 
   A DVD disc  309  as a first recording medium is located at a predetermined position to be described later on the disc tray  307 . 
   A partially enlarged view showing a structural relationship among the tray guide  311 , the disc tray  307  and the DVD disc  309  is shown in FIG.  8 . 
     FIG. 4  is a perspective view showing a key portion of the ink jet recording apparatus in the embodiment of the invention. A carriage  317  on which an ink cartridge  315  and a recording head  319  supplied with ink from the ink cartridge  315  is supported by carriage shafts  321  and  323 , and is adjustable in height. The carriage is driven by a carriage motor (not shown) through power transmission means (not shown), such as a timing pulley and a timing belt, and is reciprocatively movable in the main scan direction (parallel to the carriage shafts  321  and  323 ). 
   Specific mechanical components necessary for the printing, such as the ink cartridge  315 , the carriage  317  and the recording head  319 , may be those disclosed in Japanese patent application No. 2002-038117 (filed on Feb. 15, 2002). 
   A gear  343  is formed at an end of the disc tray  307 . A pinion  347  provided on a motor  345  engages with the gear, so that a drive force of the motor  345  is transmitted to the disc tray  307 . The disc tray  307  which holds the DVD disc  309  is transported in directions perpendicular to the carriage shafts  321  and  323  (a first direction and a second direction). 
   The details of the construction and operations of the ink jet recording apparatus  301  of the present embodiment will be described with reference to  FIGS. 5 through 24 . 
   Printing on a recording sheet  13  will first be described. 
   Recording sheets  313  as second recording media are set in the sheet feed tray  303  as a medium tray. The recording sheets  313  are picked up sheet by sheet by a pickup roller  325  as a feed roller. 
   A bottom plate  414  of the sheet feed tray  303  is lifted at its part closer to the pickup roller  325  as shown in  FIGS. 22 and 23  by a lift-up mechanism (not shown), and the recording sheet is picked up in a state that the pickup roller  325  is in contact with the recording sheet  313 . 
   A recording sheet  313  picked up is transported by feed rollers  327  and  329 , both rotating clockwise, and gains a further transporting force between the pinch roller  331  and the main roller  333  as a transporting roller. 
   The main roller  333 , which determines a transporting accuracy of the recording sheet  313 , includes a rotary encoder (not shown) for measuring a rotation accuracy, which is mounted on the same shaft as of the main roller. 
   The rotary encoder is preferably located at a position where it does not hinder the loading/unloading of the ink cartridge  315  and setting/removing of the recording sheets  313 . 
   The recording sheet  313  having passed through between the pinch roller  331  and the main roller  333  is subjected to an image forming process. In the process, the recording head  319  ejects ink onto the recording sheet to form a given image thereon. Then, the recording sheet passes between the plurality of discharge rollers  339  and  341 , and the free rollers  335  and  337 , and is discharged to outside the ink jet recording apparatus  301 . 
   Those free rollers  335  and  337  are provided to minimize an area on the recording sheet  313  which receives ink ejected from the recording head and hence, to prevent its ink stain. 
   In the instant embodiment, the motor  345 , the pinion  347 , the pinch roller  331  and the main roller  333  are used for a first transporting system, and the pickup roller  325 , the feed rollers  327  and  329 , pinch roller  331 , main roller  333 , free rollers  335  and  337 , and discharge rollers  339  and  341  are used for a second transporting system. 
   Operation of printing on the DVD disc  309  will be described with reference to a flow chart of FIG.  24 . 
   To start, a power switch of the ink jet recording apparatus  301  is turned on, and then the disc tray  307  is put in a print ready state at a print ready position in a step  1  (ST  1 ) in the flow chart of FIG.  24 . 
   Referring to  FIGS. 5 and 6 , there is shown a state that the disc tray is in the print ready position when the disc tray  307  is accommodated in the ink jet recording apparatus  301  (A position of the disc tray  307  in this state will be referred to as a “print ready position”). An enlarged view of a key portion of the structure illustrated in  FIG. 6  is shown in FIG.  9 . 
   Then, at a step  2  (ST  2 ) an operator turns on the disc loading switch  308 . A step  3  (ST  3 ) is executed, and as shown in  FIG. 10 , the carriage  317 , the pickup roller  325 , the feed roller  327  and the free rollers  335  and  337  are moved upward to a predetermined height (This height will be referred to as a “release height”) by a motor and a link mechanism, both not shown. 
   At the release height, the recording head  319 , and the free rollers  335  and  337  are at a position of printing on the DVD disc  309 . 
   Thereafter, a step  4  (ST  4 ) is executed, and as shown in  FIG. 11 , the pinch roller  331  ascends to a disc pull-in height, and a step  5  (ST  5 ) is executed, and the disc tray  307  is transported to the front of the ink jet recording apparatus  301  (in a direction of an arrow in FIG.  12 ). 
   In this case, the disc tray  307  is transported in a manner that the pinion  347  of the motor  345  engages with the gear  43  of the disc tray  307 . 
   Next, if in a step  6  (ST  6 ), it is judged that a leading end of the disc tray  307  passed under the pinch roller  331  as shown in  FIG. 12 , then a step  7  (ST  7 ) is executed and as shown in  FIGS. 15 and 16 , the pinch roller  331  descends to come in contact with the disc tray  307 , so that a rotational force of the main roller  333  is transmitted to the disc tray  307 . 
   Thereafter, a step  8  (ST 8 ) is executed and the disc tray  307  is transported to a position shown in  FIGS. 14 ,  17  and  18  (This position of the disc tray  307  will be referred to as a “loading/unloading position”). In a step  9  (ST  9 ), the operator places the DVD disc  309  as an object under printing on the disc tray  307 . 
   Thereafter, the operator turns on the disc loading switch  308  in a step  10  (ST  10 ). Then, in a step  11  (ST  11 ), the disc tray  307  is transported, by a rotation force of the main roller  333 , to a position shown in  FIGS. 19 and 20  (This position will be referred to as a “print start position”). 
   Next, in a step  12  (ST  12 ), a sensor (not shown) detects whether or not the DVD disc  309  is located on the disc tray  307 . If the DVD disc  309  is not located, a step  22  (ST  22 ) is executed and the disc tray  307  moves to a print ready position shown in FIG.  21 . If the DVD disc  309  is located, a step  13  (ST  13 ) is executed to issue a print instruction, and in a step  14  (ST  14 ), operation of printing on the DVD disc  309  is performed. 
   In a step  15  (ST  15 ), if the printing on the DVD disc  309  ends, the disc tray  307  moves to the loading/unloading position in a step  16  (ST  16 ). In a step  17  (ST  17 ), the operator takes out the DVD disc  309  after the printing operation ends. And a step  18  (ST  18 ) is executed. 
   In a step  18  (ST  18 ), the operator places a new DVD disc  309  on the disc tray  307 , and in a step  19  (ST  19 ), and turns on the disc loading switch  308 . In a step  20  (ST  20 ), the disc tray  307  is transported to the print start position shown in  FIGS. 19 and 20 . In a step  21  (ST  21 ), a sensor (not shown) detects whether or not the DVD disc  309  is located on the disc tray  307 . 
   When the DVD disc  309  is placed on the disc tray  307  in the step  21  (ST  21 ), the step  13  (ST  13 ) is executed, and the operation of printing on the DVD disc  309  is performed. 
   If the DVD disc  309  is not present on the disc tray  307  in the step  21  (ST  21 ), the step  22  (ST  22 ) is executed, and the disc tray  307  is transported to the print ready position shown in  FIG. 21  by a transporting force of the main roller  333  and the motor  345 . If during the course of movement to the print ready position, if the end  377  of the disc tray  307  passes under the pinch roller  331 , the pinch roller  331  automatically descends to a normal position shown in  FIG. 21  by a pressing force of a spring (not shown). 
   Thereafter, in a step  23  (ST  23 ), the carriage  317 , the pickup roller  325 , the feed roller  327 , and the free rollers  335  and  337  are adjusted to a normal sheet height shown in  FIGS. 5 ,  6  and  9  by a link mechanism, and then a print ready position is set up in a step  24  (ST  24 ). 
   As described above, in other cases than the case where the operator inserts the DVD disc  309  into and draws it out of the ink jet recording apparatus or takes out the discharging sheet therefrom, the disc tray  307  is accommodated in the ink jet recording apparatus  301 , and hence, a part protruded to outside the recording device is not present. Further, the operations, such as the insertion/drawing-out of the DVD disc  309 , the operation of the disc loading switch  308 , the taking-out of the discharging sheet, loading/unloading of the sheet feed tray  303 , may all be performed on the main operation panel. Accordingly, the ink jet recording apparatus  301  may be accommodated compactly in, for example, a television rack in a home. 
   The height of the pinch roller  331  may be preset in accordance with a thickness of an object under printing. In alternative, a thickness of the object under printing is detected by a sensor (not shown), and the height of the pinch roller  331  may automatically be adjusted according to the detected thickness. 
   The DVD disc  309  is exemplarily presented as the first recording medium in the first embodiment described above. However, the first recording medium may be any other recording medium if it is smaller than the ink jet recording apparatus  301 , and may be placed on the disc tray  307  having a predetermined configuration. Examples of the first recording media are an optical recording medium, e.g., CD, a magnetic recording medium, e.g., a flexible disc, an electronic recording medium, e.g., an IC card or a semiconductor memory, a plastic card, e.g., a credit card or a cash card, a resin solid material, e.g., a name card case, and a metal solid material, e.g., an aluminum plate. 
   &lt;Second Embodiment&gt; 
     FIG. 25  is a side view conceptually showing an exemplary application of an ink jet recording device as an embodiment of the invention when it is installed in a home-use television rack. In the figure, a television set  1  is placed on a rack  3 , which is provided with a glass door  5  that may be opened and closed. 
   A videocassette recorder (VCR)  7 , a DVD recorder  9 , and an ink jet recording device  10  as a second embodiment of the invention are accommodated in the rack  3  in a stacked fashion. 
   A discharge tray  12  to be described later is illustrated in a state that it is protruded outside from the ink jet recording device  10  so as to enable an operator to load an optical recording medium, such as CD or DVD, and to take out a discharging sheet. 
     FIG. 26  is a perspective view showing an external appearance of an ink jet recording device  10  which is a second embodiment of the invention in a state that the discharge tray  12  is accommodated in the recording device. 
     FIG. 27  is a perspective view showing an external appearance of the ink jet recording device  10  in a state that apart of the discharge tray is protruded outside the device (A position of the discharge tray in this state will be referred to as “discharge-tray open position”, hereinafter).  FIG. 28  is a perspective view showing an external appearance of the ink jet recording device  10  in a state that the discharge tray  12  is drawn out to the full extent (A position of the discharge tray in this state will be referred to as “discharge-tray maximum drawn-out position”, hereinafter).  FIG. 29  is a perspective view showing an external appearance of the ink jet recording device  10  in a state that a tray guide  16  is pulled up in order to take out a discharging sheet  14  at the discharge-tray maximum drawn-out position. 
   In  FIGS. 26 through 29 , various switches  17  of the on/off type, such as a power switch and a discharge-tray open switch, and various indicator lamps  18  for indicating statuses of those switches  17  are installed on a main operation panel of the ink jet recording device  10 . 
   An ink replacement cover  19  is used in such a manner that when an ink cartridge  24  is replaced with another cartridge, it is opened as shown in FIG.  26 . 
   The tray guide  16  is integrally formed on the discharge tray  12 , and a guide part  72  for guiding the disc tray  20  is formed on the tray guide  16 . 
   The disc tray  20  is mounted on the tray guide  16 , and a DVD disc  22  is placed at a predetermined position to be described later on the disc tray  20 . 
   A partially enlarged view showing a structural relationship among the tray guide  16 , the disc tray  20  and the DVD disc  22  is shown in FIG.  42 . 
     FIG. 30  is a perspective view showing a key portion of the innards of the ink jet recording device  10  as the second embodiment of the invention. A carriage  26  on which the ink cartridge  24  and a recording head  30  ( FIG. 32 ) supplied with ink from the ink cartridge  24  are mounted, is supported on cr transmitting means (not shown), such as timing pulleys and a timing belt, and is reciprocatively movable in the main scan directions (parallel to the shafts  28  and  29 ). 
   Specific mechanical components necessary for the printing, such as the ink cartridge  24 , the carriage  26  and the recording head  30 , may basically be those which are known. Those disclosed in Japanese patent application No. 2002-038117 (filed on Feb. 15, 2002 (Heisei 14) by the same Applicant as of the present patent application) may be used for those mechanical components. 
   A plastic plate  32  as a pressing member presses the discharge tray  12  toward the main operation panel with the aid of a coiled spring  34 . A similar combination of the plastic plate and the coiled spring, both not shown, are likewise contained also in a sheet feed cassette  40 . 
   The disc tray  20  is provided with a motor  36  having a pinion  3 . When this pinion  35  engages with a gear part  38 , which is provided at an end of the disc tray  20 , a drive force of the motor  36  is transmitted to the disc tray  20 , and the he disc tray  20 , which holds the DVD disc  22 , is transported in a direction orthogonal to the carriage shafts  28  and  29 . 
   An engagement cutout  39  shown in  FIG. 33A  is formed at a part of the guide part  72  provided on the tray guide  16 . At the engagement cutout  39 , the pinion  35  provided on the engagement cutout  39  engages with the gear part  38  provided at an end of the disc tray  20 . 
   As shown in  FIG. 33B , an idle gear  37  maybe interposed between the pinion  35  of the motor  36  and the gear part  38 , while being provided on the tray guide  16 . 
   In this case, the idle gear  37  and the pinion  35  are preferably arranged such that their axial centers are shifted from each other in a direction orthogonal to the main scan direction. Where so arranged, when the tray guide  16  moves and the idle gear  37  comes in contact with the pinion  35 , the idle gear  37  are brought into engagement with the pinion  35  such that the teeth of the idle gear  37  obliquely contact with the teeth of the pinion  35 , thereby ensuring a reliable engagement of them. 
   The details of the construction and an outline of operation of the ink jet recording device  10  of the present embodiment will be described with reference to  FIGS. 31 through 45 . 
   Reference is made to  FIGS. 31 and 32 . In those figures, by an operation by an operator on the main operation panel, the DVD disc  22  as a first recording medium is placed on the disc tray  20  as a medium holding plate in a state that the discharge tray  12  shown in  FIGS. 28 ,  29  and  34  is maximumly protruded outside (discharge-tray maximum drawn-out position). Then, the discharge tray  12  is accommodated into the ink jet recording device  10  by manual operation or an electric motor (not shown), and in this state (FIG.  26 ), the ink jet recording device is in a print ready state (A position of the disc tray  20  in this state will be referred to as a “print ready position”). 
   In  FIGS. 27 and 33A , there is illustrated a state that a part of the discharge tray  12  is protruded outside (discharge-tray open position). 
   Printing on a recording sheet  41  as is stored in the sheet feed cassette  40  will first be described. 
   As in the case of the discharge tray  12 , from the main operation panel, recording sheets  41  have been set in the sheet feed cassette  40  as a medium supplying part, which is accommodated in the ink jet recording device  10 . The recording sheets  41  are picked up sheet by sheet by a pickup roller  43  supported on a shaft  42 . Thereafter, the recording sheet  41  picked up is transported by sheet feed rollers  45  and  47 , which are both rotated clockwise, and reaches a U-turn roller  50  supported by a shaft  48 . 
   A shaft  46  and the sheet feed roller  47  are provided in the sheet feed cassette  40 , as shown in FIG.  41 . The recording sheet  41 , which is reversed in its transporting direction by the U-turn roller  50 , gains a further transporting force between a pinch roller  52  and a main roller  54 . 
   The main roller  54 , which determines a transporting accuracy of the recording sheet, includes a rotary encoder (not shown) for measuring a rotation accuracy, which is mounted on the same shaft as of the main roller. 
   The rotary encoder is preferably located at a position where it does not hinder the loading/unloading of the ink cartridge  24  and setting/removing of the recording sheets. 
   The recording sheet  41  having passed through between the pinch roller  52  and the main roller  54  is subjected to an image forming process. In the process, the recording head  30  ejects ink onto the recording sheet to form a given image thereon. Then, the recording sheet passes between the plurality of discharge rollers  56  and  58 , and the free rollers  60 ,  62  and  64 , and is discharged into the discharge tray  12 . 
   A plurality of free rollers  60  are supported on a shaft  66 ; a plurality of free rollers  62 , on a shaft  68 ; and a plurality of free rollers  64 , on a shaft  70 . Those free rollers  60 ,  62  and  64  are provided to minimize an area on the recording sheet  41  which receives ink ejected from the recording head  30  and hence, to prevent its ink stain. 
   Operation of printing on the DVD disc  22  held on the disc tray  20  will be described. 
   In a print ready position shown in  FIGS. 31 and 32 , when the motor  36  is rotated clockwise, the pinion  35  engages with the gear part  38 , so that the disc tray  20  is transported toward the carriage shafts  28  and  29  along the guide part  72  provided on the tray guide  16 . And as shown in  FIGS. 35 and 36 , a leading end  74  of the disc tray  20  reaches between the pinch roller  52  and the main roller  54  (a position of the disc tray  20  in this state will be referred to as a “disc tray pull-in position”). 
   In other cases than the printing on the recording sheet  41 , inclusive of a case where the disc tray is transported from the print ready position to the disc tray pull-in position, the free gears  60 ,  62  and  64  automatically move upward by a mechanism to be described later ( FIG. 36 ) to thereby eliminate a chance of damaging the DVD disc  22  by the free gears  60 ,  62  and  64 . 
   The U-turn roller  50 , the main roller  54  and the discharge rollers  56  and  58  are driven in an interlocking mannerm, and the rotational directions of those rollers maybe switched in accordance with a transporting direction of the disc tray  20 . 
   When the disc tray  20  passes a region (first region) where it is driven by the motor  36  and the leading end  74  of the disc tray  20  reaches a position between the pinch roller  52  and the main roller  54 , then the pinch roller  52  descends. In a region located further ahead (second region), the disc tray  20  is transported by the combination of the pinch roller  52  and the main roller  54 . As shown in  FIGS. 37 and 38 , a trailing end  76  of the DVD disc  22  is located at a position closer to the U-turn roller  50  than the recording head  30  (This position of the disc tray  20  will be referred to as a “print start position”). 
   Thereafter, the disc tray  20  is transported from the print start position toward the first region by the combination of the pinch roller  52  and the main roller  54 , while at the same time the recording head  30  prints on the DVD disc  22 . 
   Upon completion of the printing operation on the DVD disc  22  by the recording head  30  and the transportation of the disc tray toward the first region by the combination of the pinch roller  52  and the main roller  54 , the disc tray  20  moves to the first region as shown in  FIGS. 39 and 40  (A position of the disc tray  20  shown in  FIGS. 39 and 40  will be referred to as a “print end position”), and is transported to the print ready position by the motor  36 . 
   In the light of preventing the irregular transportation, it is preferable that the disc tray  20  is flush with the DVD disc  22 . 
   In the present embodiment, after the printing on the DVD disc  22  ends, the disc tray  20  is transported to the print ready position shown in  FIGS. 31 and 32 , and the indicator lamp  18  is energized to show the end of printing to the operator. In place of using the indicator lamp  18  to show the end of printing, the following alternative may be employed. The disc tray is automatically moved to the discharge-tray open position or the discharge-tray maximum drawn-out position by use of a motor (not shown), to thereby show the end of printing. 
   In another alternative, after the end of printing, the disc tray stays at the print end position, and the operator operates one of the switches  17 , whereby the motor  36  and another motor (not shown) are operated and the disc tray  20  is automatically ejected outside. 
   A major part of a moving mechanism including the carriage  26 , the pinch roller  52 , and the free gears  60 ,  62  and  64  is shown in  FIGS. 43  to  45 . 
   The free roller  64  is omitted for ease of explanation. 
     FIGS. 43 and 47  show a position of the disc tray when the ink jet recording device is in a print ready state. The recording head  30 , the carriage  26 , the pinch roller  52 , and the free rollers  60  and  62  are at the same position as at the time of printing on the recording sheet  41  (This position will be referred to as a “normal sheet printing position”). At this position, the recording head  30 , the carriage  26 , the pinch roller  52 , and the free rollers  60  and  62  are at the lowest position. 
   A gear  80  is provided on a chassis side plate  11 . The gear  80  includes a large-diameter part  82  and a small-diameter part  84 . 
   A gear  86  is provided on the carriage shaft  28 , and will be in mesh with the large-diameter part  82  of the gear  80 . 
   The small-diameter part  84  of the gear  80  is in mesh with a gear  92 , which is in mesh with a gear  90  having a cam  91 . 
   A pinch roll holder  94  rotatably holds the pinch roller  52  at its top end. The pinch roller  52  vertically moves in accordance with a contact state between the cam  91  of the gear  90  and the pinch roll holder  94 . 
   The gear  86  interlocks with the free rollers  60  and  62 , through a link mechanism  96 . 
   With such a construction, the carriage shafts  28  and  29  move upward in the drawing under driving of a motor (not shown). With this, the carriage  26  and the recording head  30  move upward. 
   With this, the gears  86 ,  80 ,  92  and  90  also rotate, and the pinch roller  52  moves upward as shown in FIG.  44 . 
   The free gears  60 ,  62  and  64  also move upward through the link mechanism  96 . 
   At the disc tray pull-in position, the carriage  26 , the pinch roller  52 , and the free gears  60 ,  62  and  64  are at a position shown in  FIG. 44  (This position will be referred to as a “disc pull-in position”). 
   With this, when the disc tray  20  moves from the first region to the second region, the disc tray  20  is smoothly transported to the second region without hitting the recording head  30 , the pinch roller  52 , and the free gears  60 ,  62  and  64 . And, there is no danger that the free gears  60 ,  62  and  64  damage the surface of the DVD disc  22 . 
   When it is detected that the leading end  74  of the disc tray  20  passes under the pinch roller  52 , the pinch roller  52  descends as shown in FIG.  45  and comes in contact with the disc tray  20  (The position shown in  FIG. 45  will be referred to as a “disc print position”). In the second region, the disc tray  20  is transported by the combination of the pinch roller  52  and the main roller  54 . 
   At the print start position, in-printing, and the print end position, a pinch-roller distance changing mechanism is at the disc print position, the recording head  30  has been raised to an optimum height with respect to the disc tray  20  or the DVD disc  22 , and the free gears  60 ,  62  and  64  has also been raised in link to the recording head. Accordingly, the free gears  60 ,  62  and  64  do not a but against the DVD disc  22  immediately after the printing. Accordingly, there is no chance of damaging the surface of the DVD disc  22 . 
   At the time of printing, a distance of the recording head  30 , which is coupled to the pinch-roller distance changing mechanism, to the DVD disc  22  and the recording sheet  41 , is kept at a fixed distance by the pinch-roller distance changing mechanism. Accordingly, an optimum printing state can always be secured. 
   Detailed operations of the thus constructed ink jet recording device  10  in the present embodiment will be described with reference to  FIGS. 46  to  54 . 
     FIG. 46  is a flow chart useful in explaining operations of the ink jet recording device  10  in the embodiment. 
   To start, an operator opens the glass door  5  and turns on a power switch, and then the disc tray  20  watches and waits at the print ready position. 
   At the print ready position, the carriage  26 , the pinch roller  52  and the free gears  60 ,  62  and  64  are at the normal sheet printing position shown in FIG.  47 . 
   The free rolls  64  are somewhat lower than the free rollers  60  and  62 . Accordingly, when the recording head prints on the recording sheet  41  in the sheet feed cassette, it is transported somewhat downwardly by the free roller  64  after the printed recording sheet  41  passes the free rollers  60  and  62 , and it is smoothly discharged into the discharge tray  12 . 
   Next, the operator turns on the discharge tray open switch  17 . Then, the discharge tray  12  is ejected to the discharge-tray open position shown in  FIGS. 27 and 33A . 
   Then, the operator draws out the discharge tray  12  to the discharge-tray maximum drawn-out position, places a disc  22  on the disc tray  20 , and then pushes the discharge tray  12  into the ink jet recording device  10 . 
   To take out a discharging sheet (the recording sheet  41  after the printing thereon is completed) from the discharge tray  12 , the disc tray  20  is raised as shown in  FIG. 29 , and in this state, the discharging sheet is taken out. 
   When a print instruction is issued, a sensor (not shown) provided in the ink jet recording device  10  judges whether or not a disc  22  is present on the disc tray  20 . If the disc is not present, the ink jet recording device, the disc tray stands by as it stands, viz., it stands by at the print ready position shown in  FIGS. 31 and 32 . 
   If the DVD disc  22  is present, the recording head  30  and the free gears  60 ,  62  and  64  ascends to the disc print position shown in  FIG. 48  in accordance with a thickness of the disc tray  20  or the DVD disc  22 , and the pinch roller  52  also ascends to the disc tray pull-in height shown in FIG.  49 . Those are at the disc pull-in position shown in  FIGS. 44 and 49 . 
   Thereafter, the disc tray  20  is transported toward the recording head  30 , and if it is judged that the leading end  74  of the disc tray  20  passed under the pinch roller  52  as shown in  FIG. 50 , the pinch roller  52  descends as shown in  FIG. 51 , and it continues the transportation of the disc tray  20 . 
   Thereafter, the disc tray  20  moves to the print start position shown in  FIGS. 37 ,  38  and  52 , and then an operation of printing on the DVD disc  22  starts (FIG.  53 ). When the operation of printing on the disc ends, the disc tray  20  is transported to the print end position shown in  FIGS. 39 and 40 . 
   At this time, after the leading end  74  of the disc tray  20  passed under the pinch roller  52 , the pinch roller  52  automatically descends to a position shown in  FIG. 54   
   Thereafter, the disc tray  20  is transported, by the motor  36 , to the print ready position, and is ready for printing at the print ready position, and the recording head  30  and the free gears  60 ,  62  and  64  are returned to a position when printing is made on the recording sheet in the sheet feed cassette  40 , viz., the normal sheet printing position shown in  FIGS. 32 and 47 . 
   If in this print ready state, the operator turns on the discharge tray open switch  17 , then the discharge tray  12  is ejected to the discharge-tray open position shown in  FIGS. 27 and 33A . 
   Then, the operator draws out the discharge tray  12  to the discharge-tray maximum drawn-out position, takes out the printed disc  22  on the disc tray  20 , and then pushes the discharge tray  12  completely into the ink jet recording device. 
   Thereafter, the disc tray stands by again at the print ready position shown in  FIGS. 31 and 32 . 
   Modifications of the present embodiment are shown in  FIGS. 55  an  56 . 
   A difference of the modification shown in  FIG. 55  from the second embodiment mentioned above resides in that after the printing on the disc  22  is completed and the disc tray  20  is moved to the print ready position, the discharge tray  12  is automatically ejected to the discharge-tray open position even if the operator does not turn on the discharge tray open switch  17 . 
   A difference of another modification shown in  FIG. 56  from the second embodiment mentioned above resides in that after the printing on the disc  22  is completed and the disc tray  20  is moved to the print ready position, the discharge tray  12  is automatically ejected to the discharge-tray open position after it stands by till a predetermined time (e.g., 10 seconds or longer) elapses to dry ink on the disc  22 . 
   As described above, in the present embodiment, the disc tray  20  having the DVD disc  22  that was mounted thereon by the operator on the main operation panel, is accommodated into the ink jet recording device  10  in the main scan direction of the recording head  30 , and transported in a direction orthogonal to the main scan direction, and then the printing on the disc is performed. Accordingly, the size of the ink jet recording device  10  as viewed in the direction orthogonal to the main scan direction, may be reduced, when comparing with the case where the DVD disc  22  is placed in the direction orthogonal to the main scan direction. 
   In other cases than the case where the operator inserts the DVD disc  22  into and draws it out of the ink jet recording device or takes out the discharging sheet therefrom, the disc tray  20  is accommodated in the ink jet recording device  10 . Further, the operations, such as the insertion/drawing-out of the DVD disc  22 , the taking-out of the discharging sheet, loading/unloading of the sheet feed cassette, may all be performed on the main operation panel. Therefore, the operator can execute the printing process by use of the ink jet recording device even in a state that the glass door  5  of a television rack or the like is left closed, and the ink jet recording device  10  may be accommodated compactly in, for example, a television rack in a home. 
   When the disc tray  20  is transported in the direction orthogonal to the main scan direction, a reliable transportation of the disc tray in a first direction which is orthogonal to the main scan direction is ensured since the first region where the disc tray is transported under driving of the motor  36  and the second region where the discharge tray is transported by the combination of the pinch roller  52  and the main roller  54  are provided. 
   When the first region where the disc tray is transported under driving of the motor  36  and the second region where the discharge tray is transported by the combination of the pinch roller  52  and the main roller  54  are disposed while partially overlapping with each other, the transportation of the discharge tray in the second region smoothly succeeds the transportation of the discharge tray in the first region. 
   In printing on a recording sheet as a second recording medium, a given image is formed on the image-bearing recording sheet by ink ejected from the recording head  30 , and then the recording sheet passes between the discharge rollers  56  and  58  and the free gears  60 ,  62  and  64 , and is discharged into the discharge tray  12 . The discharge tray  12  is disposed between the tray guide  16  and the sheet feed cassette  40 , while being parallel to the latter. Therefore, the ink jet recording device  10  is reduced in size. 
   It is most preferable that the discharge tray  12  is disposed between the tray guide  16  and the sheet feed cassette  40 . If required, it maybe disposed under the sheet feed cassette or above the tray guide  16 . 
   By adjusting a height of the pinch roller  52  by use of the pinch-roller distance changing mechanism shown in  FIGS. 43  to  45 , a part of the transporting system of the disc tray  20  and a part of the transporting system of the recording sheet  41 , viz., the pinch roller  52  and the main roller  54 , may be used in common. Accordingly, the size of the whole device is reduced. As a result, the ink jet recording device  10  may be accommodated compactly in, for example, a television rack in a home. 
   The height of the pinch roller  52  may be set in advance in accordance with a thickness of an object under printing. In an alternative, a thickness of the object under printing is detected by a sensor (not shown), and a height of the pinch roller  52  is automatically adjusted in accordance with the thickness detected. 
   Linking with the selection of the height of the pinch roller  52  by the pinch-roller distance changing mechanism shown in  FIGS. 43 through 45 , the height of the recording head  30  and the free gears  60 ,  62  and  64  is also adjusted. Therefore, there is no need of providing individual drive mechanisms, and hence, device size reduction is realized. 
   The DVD disc  22  is exemplarily presented as the first recording medium in the second embodiment described above. However, the first recording medium may be any other recording medium if it is smaller than the ink jet recording device, and may be placed on the disc tray  20  having a predetermined configuration. Examples of the first recording media are an optical recording medium, e.g., CD, a magnetic recording medium, e.g., a flexible disc, an electronic recording medium, e.g., an IC card or a semiconductor memory, a plastic card, e.g., a credit card or a cash card, a resin solid material, e.g., a name card case, and a metal solid material, e.g., an aluminum plate. 
   The tray guide  16  as the guide part is formed on the discharge tray  12 . When the disc tray  20  is moved in a second direction parallel to the main scan direction, the disc tray  20  is held and fixed to the tray guide  16 . When the disc tray  20  is moved in the first direction orthogonal to the main scan direction, the tray guide  16  is prohibited from moving, but only the disc tray  20  is permitted to move. Accordingly, for the movement of the DVD disc  22  in the first direction, only the disc tray  20  is transported, and for the movement of the DVD disc  22  in the second direction, only the tray guide  16  is driven. Thus, the disc tray  20  may be moved in two different directions (perpendicular to each other) and compactly. Further, the ink jet recording device may be operated from the front side of the rack. 
   &lt;Third Embodiment&gt; 
   An ink jet recording device  100  which is a third embodiment of the invention will be described with reference to  FIGS. 57 through 73 . 
   Throughout the drawings, in the descriptions of the second and subsequent embodiments of the invention, like or equivalent portions will be designated by like reference numerals, for simplicity. 
     FIG. 57  is a perspective view showing a key portion of the innards of the ink jet recording device in the third embodiment of the invention. The third embodiment is greatly different from the second embodiment in the following points. The tray guide  102  is not integral with a discharge tray  120 , but is supported on a tray guide holder  122 . A tray guide  102  is driven to move in directions parallel to the carriage shafts  28  and  29  by a combination of a pinion  107  provided on a motor  106  and a rack  104  provided on the tray guide  102 . A transportation of a disc tray  108  in a direction orthogonal to the carriage shafts  28  and  29  in a first region is performed by use of an auxiliary roller  112  coupled to a tray transporting roller  116  and a roller shaft  110  containing a spring mechanism therein. 
   Other points are substantially the same as those in the second embodiment. 
   Operations of the ink jet recording device  100  of the third embodiment shown in  FIGS. 57 through 73  will be described with reference to FIG.  73 . 
   As shown in  FIG. 73 , an operator first turns on a power switch. Then, the tray guide  102  with the disc tray  108  put thereon is placed to a print ready state at a print ready position shown in  FIGS. 59  to  61 . 
   When the operator turns on a disc loading switch (not shown), the motor  106  is driven to move the tray guide  102  to a disc loading/unloading position shown in  FIGS. 62 and 63 . 
   Then, the operator places the disc  22  on the disc tray  108  on the tray guide  102 , and turns on again the disc loading switch. In turn, the tray guide  102  moves to the print ready position. 
   Tapered parts  114  and  118 , as shown in  FIG. 58 , are formed on the auxiliary roller  112  and the tray transporting roller  116  driven by a motor (not shown). Accordingly, the disc tray  108  is smoothly disposed between the auxiliary roller  112  and the tray transporting roller  116 . 
   And, the recording head  30  and the free rollers  60  and  62  ascend to the disc print position, and the pinch roller  52  also ascends to the disc tray pull-in position. 
   By a drive force of the tray transporting roller  116 , the disc tray  108  is transported toward the recording head  30 , and reaches a disc pull-in start position shown in  FIGS. 64 ,  65  and  66 . 
   When it is judged that the leading end  74  of the disc tray  20  passed under the pinch roller  52 , the pinch roller  52  descends. Thereafter, the disc tray  108  moves to the print start position shown in  FIGS. 67 ,  68  and  69 , and then operation of printing on the disc  22  starts. 
   When the operation of printing on the disc  22  ends, the disc tray  108  is transported to the print end position shown in  FIGS. 70 ,  71 , and  72 . 
   Thereafter, the disc tray  108  is transported to the print ready position shown in  FIGS. 59 ,  60  and  61 , and put to a print ready state. 
   When it is judged that in this state, the operator turned on the disc loading switch, a computer (not shown) contained in the ink jet recording device  100  judges whether or not a predetermined time (e.g., 10 seconds) has elapsed after the operation of printing on the disc  22  ends. If the predetermined time has not elapsed, the disc tray is held in the print ready state at the print ready position. If the predetermined time has elapsed, the tray guide  102  having the disc tray  108  put thereon is moved to the disc loading/unloading position shown in  FIGS. 62 and 63 . And, the operator may take out the printed disc  22 . 
   Thereafter, the operator turns on the disc loading switch to return the tray guide  102  to the print ready position. Then, a sensor (not shown) installed to the ink jet recording device  100  detects whether or not a new disc  22  is located on the disc tray  108 . If the disc  22  is located thereon, the pinch roller  52  is raised to the disc pull-in position, and subsequently, a similar printing operation is performed. If the new disc  22  is not located, the recording head  30 , the pinch roller  52  and the free rollers  60  and  62  are moved to the normal sheet printing position, and the disc tray  108  is held at the print ready position. 
   As described above, the present embodiment has the following advantages, in addition to the advantages of the second embodiment. The tray guide  102  having the disc tray  108  put thereon can be driven to move by the motor  106  without the need of operator&#39;s manual operations of drawing out the discharge tray from or pushing it into the ink jet recording device. As a result, operator&#39;s convenience is improved. 
   Further, the discharge tray  120  and the disc tray  108  may be operated independently. 
   &lt;Fourth Embodiment&gt; 
   An ink jet recording device  200  which is a fourth embodiment of the present invention shown in  FIGS. 74  to  104  will be described. 
   The fourth embodiment is greatly different from the third embodiment in that the discharge tray is turned by 90° when it is inserted into and drawn out of the ink jet recording device. 
     FIGS. 74 and 75  are each a perspective view showing a major portion of an ink jet recording device  200  as a fourth embodiment of the invention. In the illustration of  FIG. 74 , a tray-guide support plate  204  in  FIG. 75  is omitted for ease of explanation. 
   In the illustrations of the figures other than  FIGS. 75 ,  90 ,  91 ,  94  and  95 , the tray-guide support plate  204  is omitted for ease of explanation. 
   The tray-guide support plate  204  is fixed to a housing of the ink jet recording device  200 . An arcuate slit  205  is formed in the tray-guide support plate. 
   A tray guide  209  for holding a disc tray  208  on which a disc  22  is to be placed includes hook parts  214  and  212  each shaped like L. The hook part  214  is provided in a state that it is hooked to the arcuate slit  205  of the tray-guide support plate  204  and is movable along the arcuate slit  205 . 
   Further, the tray guide  209  is rotatably coupled to the tray-guide support plate  204  by means of a pin  226 . 
   The tray guide  209 , as shown in  FIGS. 77  to  80 , includes a gear part  210  which is extended from the main body of the tray guide  209  in a U-shaped fashion. The gear part  210  comes in engagement with a pinion  224  of a motor  206  (see  FIGS. 81  to  86 ). 
   An arcuate recess  220  is formed in the disc tray  208 , as shown also in  FIG. 76. A  gear part  216  is formed above the arcuate recess. 
   As shown in  FIGS. 81  to  86 , when the pinion  224  of the motor  206  comes in engagement with the gear parts  210  and  216 , two end teeth projections  222  of the gear part  210  and two end teeth projections  218  of the gear part  216  engage with the pinion  224 , while those teeth projections overlapping with each other. 
   When the disc tray  208  moves to a predetermined position, the coiled spring  202  which is provided on the housing of the ink jet recording device  200  comes in contact with the disc tray  208 , and urges the disc tray  208  toward the carriage shafts  28  and  29 . 
   As shown in  FIGS. 87  to  89 , a support shaft  234  is fastened to the housing of the ink jet recording device  200 , and two disc feeding rollers  230  are provided on the support shaft  234  through arms  232  containing springs therein. 
   The disc feeding rollers  230  stand opposite to the discharge rollers  56  and  58  in a state that a gap smaller than a thickness of the disc tray  208  is interposed therebetween, so as not to contact with discharge rollers  56  and  58 . 
   In printing on the disc tray  208 , as shown in  FIG. 89 , in a state that the free rollers  60  and  62  are raised as shown in  FIG. 89 , the disc tray  208  comes in contact with the disc feeding rollers  230  while resisting spring forces of the arms  232 . As a result, forward and reverse rotations of the discharge rollers  56  and  58  are transferred to the disc tray  208 . In this way, the disc tray  208  is transported in the second region. 
   To print on a recording sheet (normal sheet)  41  as a second recording medium, the free rollers  60  and  62  are lowered as shown in  FIG. 88 , and the free rollers  60  and  62  come in contact with a surface of the recording sheet just after its printing. As a result, the recording sheet  41  is transported (discharged) by drive forces of the discharge rollers  56  and  58 . 
   At this time, the recording sheet  41  does not contact with the disc feeding rollers  230 . 
   Size reduction of the ink jet recording device  200  inevitably results in reduction of the length of the gear part  216 . In this case, only the engagement of the pinion  224  of the motor  206  with the gear part  216  is insufficient to transport the disc tray  208  to the pinch roller  52  and the main roller  54 , thereby possibly failing to transfer the disc tray to those rollers at the time of printing on the disc  22 . To cope with this, the disc feeding rollers  230  is provided, and the disc tray  208  is transported by the utilization of the forward/reverse rotation of the discharge rollers  56  and  58 . 
   The support shaft  234 , the arms  232  and the disc feeding rollers  230  shown in  FIGS. 87 through 89  are omitted in other drawings, for ease of explanation. 
   Operations of the ink jet recording device  200  in the fourth embodiment of the invention will be described with reference to a flow charge shown FIG.  104 . 
   To start with, the operator turns on the power switch, and then the tray guide  209  having a disc tray  208  put thereon is placed in the print ready state at the print ready position shown in  FIGS. 90  to  93 . 
   Then, the operator turns on the disc loading switch (not shown). In turn, the motor  206  is driven and the pinion  224  coupled to the motor  206  comes in mesh with the gear part  210 , and the tray guide  209  moves to the disc loading/unloading position shown in  FIGS. 94  to  97 . 
   Next, the operator puts the disc  22  on the disc tray  208  on the tray guide  209 , and turns on the disc loading switch again, and the tray guide  209  moves to the print ready position. 
   Movement of the tray guide  209  in this operation is illustrated in model form in  FIGS. 81 through 86 . 
   Under driving of the motor  206 , the tray guide  209  moves from the disc loading/unloading position to the print ready position, and comes in contact with the disc tray  208  at the position in FIG.  81 . 
   With rotation of the motor  206 , the tray guide  209  is further moved to the print ready position. In turn, the disc tray  208  is gradually pressed to the carriage shafts  28  and  29  under pressing force by the coiled spring  202  (FIGS.  83  and  84 ). And, the tray guide  209  reaches the exact print ready position and is put in a state shown in  FIGS. 85 and 86 . 
   Thereafter, as in the third embodiment, the recording head  30  and the free rollers  60  and  62  ascend to the disc print position, and the pinch roller  52  also ascends to the disc tray pull-in position. 
   By the drive force of the motor  206 , the disc tray  208  is transported to the disc pull-in start position shown in  FIGS. 98  and  99 . Thereafter, by the driving forces of the discharge rollers  58  and  56 , the disc tray  208  is transported to the main roller  54 . 
   As in the third embodiment, if it is judged that the leading end  74  of the disc tray  208  passed under the pinch roller  52 , the pinch roller  52  descends. 
   Thereafter, the disc tray  208  moves to the print start position shown in  FIGS. 100 and 101 , and then, an operation of printing on the disc  22  starts. 
   Thereafter, when the printing on the disc  22  ends, the disc tray  208  is transported to the print end position shown in  FIGS. 102 and 103 . 
   Following this, the disc tray  208  is transported to the print ready position, and put in the print ready state. 
   When it is judged that in this print ready state, the operator turns on the disc loading switch, the computer (not shown) contained in the ink jet recording device  200  judges whether or not a predetermined time (e.g., 10 seconds) has elapsed after the printing on the disc  22  ends. If the predetermined time has not elapsed, the print ready state of the disc tray is maintained at the print ready position. If the predetermined time has elapsed, the tray guide  209  having the disc tray  208  put thereon is moved to the disc loading/unloading position. And, the operator may take out the printed disc  22 . 
   Thereafter, the operator turns on the disc loading switch to return the tray guide  209  to the print ready position. 
   Thereafter, the next print command is issued, a sensor (not shown) installed to the ink jet recording device  100  detects whether or not a new disc  22  is located on the disc tray  208 . If the disc  22  is located, the pinch roller  52  is raised to the disc pull-in position, and subsequently, a similar printing operation is performed. If the new disc  22  is not located, the recording head  30 , the pinch roller  52  and the free rollers  60  and  62  are moved to the normal sheet printing position, and the disc tray  208  is held at the print ready position. 
   As described above, the present embodiment has the following advantages, in addition to the advantages of the second embodiment. The tray guide  102  having the disc tray  108  put thereon can be driven to move by the motor  106  without the need of operator&#39;s manual operations of drawing out the discharge tray from or pushing it into the ink jet recording device. As a result, operator&#39;s convenience is improved. 
   Further, in the embodiment, the tray guide  209  can be transported in the main scan direction and a direction orthogonal to the main scan direction, by one motor  206 . Accordingly, size reduction of the whole ink jet recording device is realized. 
   As seen from the foregoing description, according to first aspect of the invention, a select switch is provided which switches between a protruding state and an accommodated state of the medium holding plate on the front side of the ink jet recording apparatus. The select switch, the medium tray and the medium holding plate are all operated on the front side of the ink jet recording apparatus. Accordingly, the ink jet recording apparatus may compactly be accommodated in a place having an opening only at the front, such as a television rack in a home. 
   The medium tray and the medium holding plate are disposed substantially parallel to each other. Therefore, the ink jet recording apparatus is reduced in height. The ink jet recording apparatus may compactly be accommodated in, for example, a television rack in a home. 
   The medium holding plate is transported by the first transporting system, and the second recording medium is transported by the second transporting system. Therefore, the printing on the first recording medium or the printing on the second recording medium may be selected. 
   Additionally, the first transporting system and the second transporting system include each at least one transporting roller. Therefore, the device size may be reduced without increasing the number of component parts. 
   Further, the ink jet printing apparatus includes a motor provided in the first transporting system, a pinion driven by the motor, and a gear which is provided on the medium holding plate so as to be in mesh with the pinion. A reliable switching is made between a protruding state and an accommodated state of the disc tray. 
   Further, the second transporting system includes a feed roller for transporting exclusively the second recording medium, and free rollers, in transporting the medium holding plate, the feed roller and the free roller ascend to be not in contact with the medium holding plate, and in transporting the second recording medium, the feed roller and the free roller descend to be in contact with the second recording medium. Therefore, the printing on the first recording medium on the medium holding plate may smoothly be switched to the printing on the second recording medium. 
   Further, the first transporting system and the second transporting system include each a pinch roller provided opposite to the transporting roller, and when the medium holding plate is transported to the first direction, and when a leading end of the medium holding plate as viewed in the transporting direction passes between the transporting roller and the pinch roller, a distance between the transporting roller and the pinch roller is larger than a thickness of the medium holding plate. Therefore, the medium holding plate may smoothly move from the transporting roller to the pinch roller and vice versa. 
   Further, a distance between the first recording medium and the recording head and a distance between the second recording medium and the recording head are kept constant. Therefore, the ink jet recording apparatus can adaptively handle plural types of recording media having different thicknesses without the aid of the operator. 
   Further, the medium holding plate and the medium tray are completely accommodated in the ink jet recording apparatus at least when the recording head starts to print. Therefore, there is no chance that at the time of printing on the recording medium, the medium holding plate and the medium tray protrude to outside the ink jet recording apparatus. Accordingly, there is eliminated a member protruding to outside the ink jet recording apparatus at the start of printing. Further, the operator&#39;s work to attach another member to the recording device is omitted. 
   According to the second aspect of the invention, a medium holding plate is moved out of the ink jet recording device at the time of loading and unloading of an optical recording medium. With such a construction, the medium holding plate is not protruded from the ink jet recording device at the time of printing. 
   Every kind of operation can be performed from the front side of the recording device. 
   Accordingly, the ink jet recording device may be accommodated compactly in, for example, a television rack in a home. 
   Further, the medium holding plate is transported by a first transporting system, and a second recording medium is transported by a second transporting system. It is possible to switch between the printing on the first recording medium and the printing on the second recording medium. 
   Further, every operation of the medium holding plate and a medium supplying part may be performed in one direction. Therefore, the ink jet recording device maybe installed in a place which allows one to access the interior thereof for operation in only one direction, such as a television rack in a home. 
   According to third aspect of the invention, the medium holding plate is provided above the medium supplying part. 
   Another recording medium on which a recording head prints is discharged into between the medium holding plate and the medium supplying part. Therefore, the medium holding plate, the medium supplying part and a space to which the another recording medium is discharged are efficiently disposed. Accordingly, the whole device is compact. Further, in other situations than when the optical recording medium is loaded into or unloaded from the recording device, neither the medium holding plate nor the medium supplying part is protruded from the ink jet recording device, and there is no need of providing the space into which the another recording medium is discharged, outside the ink jet recording device. 
   Further, the ink jet recording device includes a motor for driving and moving the medium holding plate in a first direction, a first region in which the motor drives and moves the medium holding plate in the first direction, and a second region in which a first transporting system drives and transports the medium holding plate in the first direction, wherein a part of a transporting path of the medium holding plate and a part of a transporting path of the second recording medium are used in common in the second region. Therefore, the recording device is reduced in size. 
   Further, the first and second transporting systems include each a pinch roller for transporting the medium holding plate and another recording medium in the first direction. The ink jet recording device includes a pinch-roller distance changing mechanism for automatically changing a distance between the pinch roller and the medium holding plate as viewed in a thickness of the medium holding plate in accordance with a thickness of the medium holding plate. With provision of the mechanism, even if the thickness of the medium holding plate changes, there is no need that the operator perform an adjusting work. 
   Accordingly, the invention produces such an excellent advantage as to eliminate troublesome operations, which are caused by the changing of the thickness of the medium holding plate, and the switching between the printing on the optical recording medium and the printing on another recording medium. 
   As seen from the foregoing description, the medium holding plate on which the first recording medium is to be placed may be transported in two directions, a first direction and a second direction. Therefore, the ink jet recording apparatus is reduced in size in the first direction, and it is compactly accommodated in, for example, a television rack in a home. 
   According to fourth aspect of the invention, the medium tray, the discharge tray, and the medium holding plate are all operated on the front side of the ink jet recording apparatus. A loading mechanism for switching between a protruding state and an accommodated state of the disc tray on the front side of the ink jet recording apparatus is provided. Therefore, the ink jet recording apparatus maybe accommodated in a place having an opening only at the front, such as a television rack in a home. 
   Further, the medium tray and the medium holding plate are disposed substantially parallel to each other. Therefore, the ink jet recording apparatus is reduced in height. The ink jet recording apparatus may compactly be accommodated in, for example, a television rack in a home. 
   The medium holding plate is transported by the first transporting system, and the second recording medium is transported by the second transporting system. Therefore, the printing on the first recording medium or the printing on the second recording medium may be selected. 
   Further, the first transporting system and the second transporting system include each at least one transporting roller. Therefore, the device size may be reduced without increasing the number of component parts. 
   Further, the loading mechanism includes a motor provided in the ink jet recording apparatus, a pinion driven by the motor, and a gear which is provided on the medium holding plate so as to be in mesh with the pinion. Therefore, the operation by the operator is easy. 
   Further, in the loading mechanism, an idle gear having an axial center which is offset from an axial center of the pinion in the first direction, is provided between the gear and the pinion. Therefore, when the guide part moves and the idle gear comes in contact with the pinion, the idle gear are brought into engagement with the pinion such that the teeth projections of the idle gear obliquely contact with the teeth projections of the pinion, thereby ensuring a reliable engagement of them. 
   Further, the first transporting system includes a medium holding plate transporting roller for transporting the medium holding plate in the first direction, a taper part tapered in the second direction is formed on the medium holding plate transporting roller, and when the medium holding plate is switched from the protruding state to the accommodated state, and the medium holding plate comes in contact with the medium holding plate transporting roller, the medium holding plate is guided by the taper part. When the medium holding plate is switched from the protruding state to the accommodated state, the medium holding plate does not hit the side surface of the medium holding plate transporting roller, and hence, the medium holding plate transporting roller reliably comes in contact with the surface of the medium holding plate. 
   Further, the first transporting system includes a pinch roller provided opposite to the transporting roller, and a pinch-roller distance changing mechanism which changes a distance between the transporting roller and the pinch roller when the medium holding plate changes its transportation along the second direction to the transportation along the first direction and when a leading end of the medium holding plate as viewed in the direction of transporting the medium holding plate passes between the transporting roller and the pinch roller. When the medium holding plate changes its transportation along the second direction to the transportation along the first direction, viz., the medium holding plate moves from the print ready position to the disc tray pull-in position, the medium holding plate reliably passes between the transporting roller and the pinch roller. 
   Further, the second transporting system includes a free roller, and a free roller select mechanism which brings the free roll into contact with the second recording medium during the transportation of the second recording medium, and lifts the free roller so as to detach the free roller from the medium holding plate during the transportation of the medium holding plate. Accordingly, during the transportation of the second recording medium, the free roller select mechanism brings the free roll into contact with the second recording medium, whereby the recording medium is smoothly transported. During the transportation of the medium holding plate, the free roller select mechanism lifts the free roller so as to detach the free roller from the medium holding plate, to thereby prevent the first recording medium on the medium holding plate from being damaged. 
   Further, the recording head is coupled to the pinch-roller distance changing mechanism, and the pinch-roller distance changing mechanism keeps constant a distance between the first recording medium and the recording head, and keeps constant a distance between the second recording medium and the recording head. Therefore, the ink jet recording apparatus can adaptively handle plural types of recording media having different thicknesses without the aid of the operator. 
   Further, the medium holding plate, the medium tray and the discharge tray are accommodated in the ink jet recording apparatus at least when the recording head ejects ink or the second recording medium is discharged into the discharge tray. Therefore, there is no chance that at the time of printing on the recording medium, the medium holding plate and the medium tray protrude to outside the ink jet recording apparatus. Therefore, the operator can execute the printing process even in a state that the glass door of a television rack or the like is left closed.