Abstract:
A recording apparatus effects recording on a recording material by a recorder. The apparatus includes a tray, mountable to the recording apparatus, for stacking a recording material, a portion to be detected, provided on the tray to permit detection of a position of the tray, and a tray position detecting portion for detecting the portion to be detected. A position of the recording material stacked on the tray is detected by detecting the position of the portion to be detected.

Description:
FIELD OF THE INVENTION AND RELATED ART 
   The present invention relates to a recording apparatus, for example, a printer, an image forming apparatus, etc., in particular, a recording apparatus capable of recording on such recording medium as a compact disc, or the like, in a tray. 
   Various recording media have been proposed as recording media on which images can be recorded by such a recording apparatus as a printing apparatus, an image forming apparatus, etc. Some of recording media are small and thick, for example, a CD-R or DVD (which hereinafter will both be referred to as compact disc or CD). Image forming apparatuses, which are widely in use have the problem that if the conveyance path through which sheets of recording medium are conveyed one by one, are used to record an image on such recording medium as a CD or the like, the media cannot be efficiently conveyed, or the media are damaged because of the higher level of rigidity thereof, or that the media fail to be conveyed because of the relationship between the size of the media and the distance between the conveyance rollers. Thus, it is common practice to use a recording medium conveyance path different from the ordinary sheet conveyance path, along with a special tray designed for this purpose, when conveying a recording medium, such as a CD, which is small and thick. 
   The above mentioned tray is thicker than an ordinary recording sheet. Therefore, serious consideration must be given to such matters as how to insert the tray between the pair of conveyance rollers, how to nip the tray by the pair of conveyance rollers, and how to maintain a proper amount of gap between the recording head and the recording medium. As one of the means for successfully using the tray, a recording apparatus is provided with a lever, which can be moved to cancel the pressure from the members for conveying the tray. More specifically, when recording using the tray, first a user is to move the lever in the direction to cancel the pressure from the members for conveying the tray, insert the tray to a predetermined point in the recording apparatus, and properly position the tray. Then, the user is to move the lever in reverse to put the pressure from the tray conveying members back onto the tray. Then, in order to secure a proper amount of gap between the recording head and the recording medium, the user is to raise the carriage, on which the recording head is present, by operating the lever. As for the detection of the position of the recording medium such as a compact disc or the like, recording is made without detecting the recording medium position, or by directly detecting the position of the white area of the image recording range of a compact disc with the use of the sensor on the carriage, before the printing. 
   Generally, an ink jet recording apparatus records images by ejecting ink onto recording media from the ejection orifices of its recording means. The recording head, that is, an ink jet recording head, of an ink jet recording apparatus is easy to reduce in size, and is capable of recording a highly precise image at a high speed. It is also low in operational cost. Further, it does not contact recording medium as it prints images, being therefore less noisy. Moreover, two or more recording heads can be used in combination with a number of inks different in color to record color images. In other words, an ink jet recording apparatus boasts a substantial number of advantages over recording apparatuses of other types. Therefore, its usage is rapidly spreading. On the other hand, there has been a substantial amount of development in the field of the materials for recording ink and recording medium. In particular, in the field of recording medium, demand has been increasing for means for recording on glossy paper, glossy film, medium in the form of a disc, for example, a compact disc, in addition to ordinary recording paper. As a means for writing (recording or printing) a title or memo on a compact disc in order to disclose its contents, a method for pasting a label onto the non-recording surface of the disc is generally used. 
   In recent years, there have become available compact discs, which are provided with a recordable area (printable area) so that a title, memo, etc., can be directly recorded thereon with the use of a sign pen, felt pen, etc. As for a means for recording on a compact disc, a recording apparatus capable of recording pertinent information on the recordable area of a compact disc in coordination with a personal computer has been known. Also in recent years, a few ink jet recording apparatuses capable of printing on a compact disc have become available in the field of a personal ink jet recording apparatus. In the case of these ink jet recording apparatuses, a unit which makes an ordinary ink jet recording apparatus capable of recording on a compact disc, and which is removably attachable to the main assembly of an ink jet recording apparatus, is provided as an accessory. 
   These recording apparatuses are structured so that a compact disc as a printing medium is mounted in a tray as a printing medium supporting means; the tray containing the compact disc is inserted into the guiding portion of the compact disc conveying portion (supporting unit) in the main assembly of the recording apparatus, to be set in the predetermined position; and the tray is conveyed into the recording apparatus; and intended letters and/or pictures are printed on the compact disc in the tray by the recording head of the recording apparatus. 
   Further, in recent years, compact discs printable by an ink jet recording apparatus have become diverse in shapes; not only are they available in the ordinary form, or a disc with a diameter of 120 mm, but also in the form of the so-called 8 cm CD, that is, a disc with a diameter of 80 mm, a rectangular recordable card with the size of a calling card, etc. The shape of a compact disc is expected to further diversify. 
   However, the above described examples of a compact disc or the like suffer from the following technical problems. 
   (1) If the position of a CD as a recording medium is not detected, recording is sometimes made on the wrong area of the compact disc due to the tolerance in component manufacture. Further, even if a compensating measure, such as accurately positioning the tray, is taken, recording (printing) is sometimes still made on the wrong area of the compact disc, due to the anomaly in the condition of the tray. 
   (2) In order to print on the white recordable (printable) area of a CD by directly detecting the position of the white recordable area with the use of a sensor mounted on the carriage, the sensor needs to be of a high performance type, adding substantially to cost. Further, a compensatory process or the like is necessary, which complicates the electrical circuit in terms of structure and control, resulting in increase in product cost, as well as recording time. 
   (3) In the case of the recording apparatuses which print on the white recordable (printable) area of a CD by directly detecting the position of the white recordable area with the use of a sensor mounted on the carriage, the position of the printable area sometimes cannot be accurately detected when printing on a colored CD, or re-printing on a CD on which printing has been already made. 
   Moreover, if a user forgets to set a CD in the tray when printing on the CD with the use of tray as described above, printing is directly made on the tray, sometimes, soiling the tray. Thus, it is necessary to detect whether or not a CD is in the tray. As the means for detecting whether or not a CD is in the tray, the following means may be considered: 
   (1) Placing a detecting means capable of directly detecting the white portion of the printable area of a CD, on the carriage; if the white portion cannot be detected by the detecting means, it is determined that a CD is not in the tray. 
   (2) Placing in a recording apparatus, a detecting means for detecting whether or not a recording medium is in the tray, in order to detect whether or not a CD is in the tray. 
   Both (1) and (2), however, suffer from the following technical problems to be solved: 
   (1) In order to directly read the white portion of the printable area of a CD, a sensor as a detecting means to be mounted on the carriage must be of a high performance type, adding to cost. Further, in order to accurately read the white portion, a complicated control means is necessary, increasing thereby the cost of the electrical circuit, as well as recording time related to processing speed. 
   (2) Generally, the means disposed in a recording apparatus to detect whether or not a recording medium is present is placed directly in contact with a recording medium in order to make it possible for the detecting means to detect even a transparent recording medium. Using this type of sensor, that is, a sensor of a direct contact type, has the possibility of damaging the surface of a CD. If the surface of a CD is damaged, not only does an image come out disarranged, but also it is possible that it will be impossible to read the information recorded on the CD. 
   For example, if a CD with a diameter of 8 cm is placed in a tray designed for a CD with a diameter of 12 cm, a recess in the form of a donut, having a width of 20 mm, is created. Therefore, one of the pair of rollers for sandwiching the tray must ride over the stepped portions of the recess, creating a problem. In this case, however, all that is necessary to solve the problem is to fit a donut-shaped adaptor, which is virtually identical in thickness to the CD, in the donut-shaped recess. In order to deal with various CD configurations, a tray adaptor is necessary for each of the various CD configurations. Further, if a user accidentally prints an image for a 12 cm CD on an 8 cm CD, it is possible that the image will extend beyond the peripheral edge of the 8 cm CD, soiling the components, etc., in the adjacencies thereof. Further, a CD is generally circular. Therefore, if an image is printed off-centered on a CD, the mistake is conspicuous, making it thereby necessary to discard the CD. In other words, printing on a circular printing medium is more likely to result in failure than printing on a non-circular recording medium. 
   SUMMARY OF THE INVENTION 
   The primary object of the present invention is to provide a recording apparatus which is capable of recording on a recording medium such as a CD in a tray as a means for supporting the recording medium, and yet, is simpler in structure and control, more inexpensive, and capable of recording on accurate spots on a recording medium, in a shorter time, than a recording apparatus in accordance with the prior art. 
   Another object of the present invention is to provide a recording apparatus, which is simpler in structure and control, and capable of detecting, more inexpensively, more accurately, and in a shorter time, than a recording apparatus in accordance with the prior arts, whether or not a recording medium such as a CD is in the means for supporting the recording medium, or the type of the recording medium in the tray, when recording on the recording medium. 
   Another object of the present invention is to provide a recording apparatus capable of recording excellent images not only on the accurate spots on a recording medium of an ordinary size, but also on the accurate spots on any of the recording mediums different in size and shape from the recording medium of the ordinary size, without the recording errors, for example, recording on the wrong spots, the cause of which is traceable to the difference in recording medium size. 
   The present invention is characterized in that a recording apparatus for recording on recording medium with the use of a recording means comprises: a tray in which recording medium is mounted, and which is mounted in the recording apparatus; a single or plurality of conveyance rollers for conveying the tray; a portion with which the tray is provided for the detection of tray position; a tray position detecting means for detecting the portion with which the tray is provided for tray position detection, and also, in that the position of the recording medium in the tray is detected by detecting the position of the portion of the tray for tray position detection. 
   Further, the present invention is characterized in that a recording apparatus for recording on recording medium with the use of a recording means comprises: a tray in which recording medium is mounted, and which is mounted in the recording apparatus; a single or plurality of conveyance rollers for conveying the tray; a portion to be detected, with which the tray is provided in order to detect the portion to be detected. 
   According to an aspect of the present invention, it is possible to provide a recording apparatus capable of recording on a recording medium such as a CD in a tray as a means for supporting the recording medium, and yet, is simpler in structure and control, more inexpensive, and capable of recording on accurate spots on a recording medium, in a shorter time, than a recording apparatus in accordance with the prior art. 
   Also according to another aspect of the present invention, it is possible to provide a recording apparatus, which is simpler in structure and control, and capable of detecting, more inexpensively, more accurately, and in a shorter time, than a recording apparatus in accordance with the prior arts, whether or not a recording medium such as a CD is in the means for supporting the recording medium, or the type of the recording medium in the recording medium supporting means, when recording on the recording medium such as a CD. 
   These and other objects, features, and advantages of the present invention will become more apparent upon consideration of the following description of the preferred embodiments of the present invention, taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of the recording apparatus in the first embodiment of the present invention. 
       FIG. 2  is a perspective view of the recording apparatus shown in  FIG. 1 , with its sheet feeding tray and delivery tray being open. 
       FIG. 3  is a perspective view of the internal mechanism of the recording apparatus shown in  FIG. 1 , as seen from the right front side thereof. 
       FIG. 4  is a perspective view of the internal mechanism of the recording apparatus shown in  FIG. 3 , as seen from the left front side thereof. 
       FIG. 5  is a vertical sectional view of the recording apparatus shown in FIG.  3 . 
       FIG. 6  is a perspective view of the recording apparatus shown in  FIG. 1 and a  CD conveying portion, prior to the mounting of the CD conveying portion into the recording apparatus. 
       FIG. 7  is a perspective view of the CD conveying portion mountable in the recording apparatus shown in FIG.  1 . 
       FIG. 8  is a perspective view of the portion of the bottom case of the recording apparatus in the first embodiment of the present invention, to which the CD conveying portion is attached, and the detecting portion of the bottom case for detecting whether or not the CD conveying portion has been attached thereto. 
       FIG. 9  is a vertical sectional view of the connective portion of the bottom case of the recording apparatus and the connective portion of the CD conveying portion, in the first embodiment of the present invention, showing how the latter is connected to the former by its hooks. 
       FIG. 10  is a perspective view of the CD conveying portion attachable to the recording apparatus, in the first embodiment of the present invention, showing the state of the CD conveying portion prior to its attachment to the recording apparatus, and the state of the CD conveying portion, the sliding cover of which has been moved after its attachment to the recording apparatus. 
       FIG. 11  is a vertical sectional view of the connective portion of the bottom case of the recording apparatus and the connective portion of the CD conveying portion, in the first embodiment of the present invention, immediately after the disengagement of the hooks of the latter from the former. 
       FIG. 12  is a vertical sectional view of the connective portion of the bottom case of the recording apparatus and the connective portion of the CD conveying portion, in the first embodiment of the present invention, showing the state of the arms before and after the movement of the sliding cover of the CD conveying portion. 
       FIG. 13  is a schematic top plan view of the tray for the CD conveying portion usable with the recording apparatus, in the first embodiment of the present invention, showing the means for calculating the recording position on a CD in the tray. 
       FIG. 14  is a schematic sectional view of the tray shown in  FIG. 13 , showing the grooves of the position detection portion. 
       FIG. 15  is a schematic top plan view of the tray shown in  FIG. 13 , showing the positional relationship between the tray and tray position detecting sensor, in various steps in the tray position detection sequence. 
       FIG. 16  is a perspective view of the recording apparatus and DC conveying portion, in the first embodiment, after the insertion of the latter into the former. 
       FIG. 17  is a vertical sectional view of the connective portion of the bottom case of the recording apparatus and the connective portion of the CD conveying portion, in the first embodiment of the present invention, showing how the tray is conveyed through them. 
       FIG. 18  is a vertical sectional view of the shaft moving mechanism of the recording apparatus, in the first embodiment of the present invention, for vertically moving the guide shaft of the carriage, when the carriage is at the lowest position and when the carriage is at the highest position. 
       FIG. 19  is a partially broken perspective view of the CD conveying portion attachable to the recording apparatus, in the first embodiment of the present invention, showing one of the rollers for keeping the CD conveying portion pressed downward, and the roller for keeping the CD conveying portion laterally pressed. 
       FIG. 20  is a schematic top plan view of the tray for the CD conveying portion usable with the recording apparatus, in the second embodiment of the present invention, showing the means for calculating the recording position on a CD in the tray. 
       FIG. 21  is a schematic top plan view of the tray for the CD conveying portion usable with the recording apparatus, in the third embodiment of the present invention, showing the means for calculating the recording position on a CD in the tray. 
       FIG. 22  is a schematic top plan view of the tray for the CD conveying portion usable with the recording apparatus, in the fourth embodiment of the present invention, showing the means for calculating the recording position on a CD in the tray. 
       FIG. 23  is a schematic top plan view of the tray for the CD conveying portion usable with the recording apparatus, in the fifth embodiment of the present invention, showing the means for calculating the recording position on a CD in the tray. 
       FIG. 24  is a schematic top plan view of the tray adaptor fitted in the tray used with the recording apparatus, in the sixth embodiment of the present invention. 
       FIG. 25  is a schematic top plan view of the tray adaptor, shown in  FIG. 24 , fitted in the tray used with the recording apparatus, in the sixth embodiment of the present invention. 
       FIG. 26  is a schematic top plan view of the tray adaptor, shown in  FIG. 24 , fitted in the tray, in the sixth embodiment of the present invention, showing the state of the adaptor when it is holding an 8 cm CD. 
       FIG. 27  is a schematic top plan view of the tray adaptor, shown in  FIG. 24 , fitted in the tray, in the sixth embodiment of the present invention, showing the state of the adaptor when it is holding a card-type CD. 
       FIG. 28  is a schematic top plan view of the tray for the CD conveying portion usable with the recording apparatus, in the seventh embodiment of the present invention, showing the means for calculating the recording position on a CD in the tray. 
       FIG. 29  is a schematic top plan view of the tray adaptor to be fitted in the tray used with the recording apparatus, in the eighth embodiment of the present invention. 
       FIG. 30  is a schematic top plan view of the tray, as a recording medium supporting means, used with the recording apparatus, in the ninth embodiment of the present invention. 
       FIG. 31  is a schematic top plan view of the tray adaptor mountable in the tray shown in FIG.  30 . 
       FIG. 32  is a frontal perspective view of the recording apparatus, and the CD conveying portion attached to the main assembly of the recording apparatus, in the ninth embodiment of the present invention. 
       FIG. 33  is a frontal perspective view of the recording apparatus and CD conveying portion, shown in  FIG. 32 , a tray, and a CD, showing where and how the tray, which is holding the CD, is inserted. 
       FIG. 34  is a perspective view of the portion of the main assembly of the recording apparatus, shown in  FIG. 32 , for anchoring the CD conveying portion. 
       FIG. 35  is a vertical sectional view of the CD conveying portion shown in FIG.  32 . 
       FIG. 36  is a vertical sectional view of the connective portion of the main assembly of the recording apparatus, and the connective portion of the CD conveying portion shown in  FIG. 35 , in the ninth embodiment of the present invention, showing the structure of the connective mechanism when the two connective portions are in the connected state. 
       FIG. 37  is a vertical sectional view of the connective portion of the main assembly of the recording apparatus, and the connective portion of the CD conveying portion, showing how the CD conveying portion is connected to the main assembly of the recording apparatus. 
       FIG. 38  is a partially broken perspective view of the recording apparatus, CD conveying portion, tray, and a CD, in the first embodiment of the present invention, as seen from diagonally above the front side of the apparatus, showing their states when the tray, which is holding the CD, is in the CD conveying portion attached to the recording apparatus. 
       FIG. 39  is an enlarged frontal perspective view of the tray shown in  FIG. 38 , and its adjacencies. 
       FIG. 40  is a vertical sectional view of the recording apparatus, CD conveying portion, tray, and a CD, shown in  FIG. 39 , showing their states when the CD is set in the recording apparatus. 
       FIG. 41  is a vertical sectional view of the recording apparatus, CD conveying portion, tray, and a CD, shown in  FIG. 39 , showing their states immediately before recording begins to be made on the CD in the main assembly of the recording apparatus. 
       FIG. 42  is a partially broken top plan view of the recording apparatus, shown in  FIG. 41 , immediately after the completion of the recording on the CD. 
       FIG. 43  is a schematic top plan view of the tray, recording head, and tray position detection sensor, in the recording apparatus, in the ninth embodiment of the present invention, showing the directions in which the tray is conveyed, the directions in which the recording head and tray position detection sensor are moved, and their positional relationship. 
       FIG. 44  is a schematic top plan view of the tray shown in  FIG. 43 , when the tray adaptor and an 8 cm CD are in their proper positions in the tray. 
       FIG. 45  is a schematic top plan view of the tray shown in  FIG. 43 , when the tray adaptor and an 8 cm CD are in its proper position in the tray. 
       FIG. 46  is a schematic top plan view of the tray shown in  FIG. 43 , when the tray adaptor and a card-type cm CD are in their proper positions in the tray. 
       FIG. 47  is a schematic top plan view of the tray shown in  FIG. 43 , when the tray adaptor is in its proper position in the tray, with no CD in the tray. 
       FIG. 48  is a schematic top plan view of the tray, recording head, and tray position detection sensor, in the recording apparatus, in the ninth embodiment of the present invention, showing their positional relationship when the tray is too far in the CD conveying portion due to user error. 
       FIG. 49  is a schematic top plan view of the surface of one (top side)of the two surfaces of the tray adaptor used with the recording apparatus, in the tenth embodiment of the present invention. 
       FIG. 50  is a schematic top plan view of the other surface (reverse side) of the tray adaptor shown in FIG.  49 . 
       FIG. 51  is a schematic top plan view of one of the variations of the tray adaptor mountable in the tray used with the recording apparatus, in any of the embodiments of the present invention, which will be described later. 
       FIG. 52  a schematic top plan view of the tray compatible with the tray adaptors shown in  FIGS. 49 and 50 . 
       FIG. 53  is a schematic top plan view of one of the variations of the tray adaptor mountable in the CD conveying portion used with the recording apparatus, in the twelfth embodiment of the present invention, showing an example of the tray adaptor openings different in shape from the conventional ones, and an example of the tray adaptor type detection holes different from the conventional ones. 
       FIG. 54  is a schematic top plan view of another variation of the tray adaptor mountable in the CD conveying portion used with the recording apparatus, in the twelfth embodiment of the present invention, showing another example of the tray adaptor openings different in shape from the conventional ones, and another example of the tray adaptor type detection holes different from the conventional ones. 
       FIG. 55  is a schematic top plan view of another variation of the tray adaptor mountable in the CD conveying portion used with the recording apparatus, in the twelfth embodiment of the present invention, which has two tray adaptor type detection holes different in location, and two sets of letters or symbols for showing the tray adaptor orientation, which are different in location. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Hereinafter, the preferred embodiments of the present invention will be concretely described with reference to the appended drawings. Incidentally, if a component in a given drawing has the same referential sign as that of a component in another drawing, the two components are identical, or similar, to each other. 
   (Embodiment 1) 
     FIG. 1  is a perspective view of the recording apparatus in the first embodiment of the present invention, and  FIG. 2  is a perspective view of the recording apparatus in  FIG. 1 , with its sheet feeding tray and delivery tray being open.  FIG. 3  is a perspective view of the internal mechanism of the recording apparatus, shown in  FIG. 1 , in the first embodiment of the present invention, as seen from the right front side, and  FIG. 4  is a perspective view of the internal mechanism of the recording apparatus, shown in  FIG. 3 , as seen from the left front side.  FIG. 5  is a vertical sectional view of the recording apparatus shown in  FIG. 3 , and  FIG. 6  is a perspective view of the combination of the recording apparatus and CD conveying portion  8  in the first embodiment of the present invention, prior to the mounting of the CD conveying portion into the recording apparatus, and  FIG. 7  is a perspective view of the CD conveying portion  8  mountable in the recording apparatus in the first embodiment.  FIGS. 8-19  are drawings for describing the structure and operation for printing on a CD, of the combination. In  FIGS. 1-5 , the recording apparatus  1  in this embodiment comprises a sheet feeding portion  2 , a sheet conveying portion  3 , a sheet delivery portion  4 , a carriage portion,  5 , a recovery mechanism portion (cleaning portion)  6 , a recording means (recording head)  7 , a CD conveying portion  8 , and an electrical portion  9 . Next, each of these portions will be roughly described in the above listed order. 
   (A) Sheet Feeding Portion 
   The sheet feeding portion  2  comprises: a pressure plate  21  on which a single or plurality of sheets P of recording medium are mounted; a sheet feeding roller (feed roller)  28  for feeding the sheets P into the main assembly of the recording apparatus; a separation roller  241  for separating the sheets P, a return lever  22  for returning the sheets P to where the sheets P were prior to the feeding, and a base  20  to which the preceding portions are attached. The sheet feeding tray  26  for holding the mounted sheets P is attached to the base  20  or the exterior of the recording apparatus. Referring to  FIG. 2 , the sheet feeding tray  26  is a collapsible type, and is to be extended for usage. 
   The feed roller  28  is in the form of a rod, which is circular in cross section. It is provided with a sheet feeding rubber roller  281 , the width of which matches the standard size of a sheet used with the recording apparatus. The sheets P are fed (sent out) into the main assembly of the recording apparatus by the feed roller  28  structured as described above. The feed roller  28  is driven by the driving force transmitted thereto from the sheet feeding motor  273  of the sheet feeding portion  2 , by way of a driving force transmission gear  271  and a planetary gear  272 . The pressure plate  21  is provided with a pair of movable side guides  23 , which controls the sheet position relative to the main assembly of the recording apparatus. The pressure plate  21  is rotatable about the shaft attached to the base  20 , and is kept pressured toward the feed roller  28  by a spring  212 . The portion of the pressure plate  21 , which opposes the feed roller  28  is provided with a separation sheet  213  for preventing the top few of the plurality of sheets P in the sheet feeding tray from being conveyed together. The separation sheet  213  is formed of a material such as artificial leather which is relatively large in friction coefficient. The sheet feeding portion  2  is structured so that the pressure plate  21  can be placed in contact with, or moved away from, the feed roller  28  by a cam  214 . 
   The separation roller  214  for separating the sheets P one by one is attached to a separation roller holder  24 , which is attached to the base  20 , more specifically, rotatably supported by the shaft attached to the base  20 . Further, the separation roller holder  24  is kept pressured toward the feed roller  28  by a separation roller spring  242 . The separation roller  241  is provided with a separation clutch (clutch spring)  243 , so that if the separation roller  241  is subjected to a load greater than a predetermined value, the separation roller  241  rotates. The sheet feeding portion is structured so that the separation roller  241  can be placed in contact with, or moved away from, the feed roller  28  by the combination of a separation roller release shaft  244  and a control cam  25 . The positions of the pressure plate  21 , return lever  22 , and separation roller  241  are detected by an ASF sensor  29 . The return lever for returning a sheet P to where it was before the feeding is rotatably attached to the base  20 , and is kept pressured by a return lever spring  221  in the direction to be released. The sheet feeding portion  2  is structured so that when returning a sheet P to where it was before feeding, the return lever  22  is rotated by the aforementioned control cam  25 . 
   Next, how a sheet of recording medium is fed by the sheet feeding portion structured as described above will be described. When the sheet feeding portion is in the normal standby state, the pressure plate  21  is prevented by the cam  214  from pressuring the sheets P, and the separation roller  241  is prevented by the control cam  25  from separating the sheets P. Further, the return lever  22  for returning the sheets P to where they were before the feeding is in the position in which it prevents sheets P from entering the recording apparatus main assembly when mounting the sheets P. As the sheet feeding portion in the above described state is started, first, the separation roller  241  is placed in contact with the feed roller  28  by being driven by the motor. Next, the return lever  22  is released, allowing the pressure plate  21  to come into contact with the feed roller  28 . In this state, the feeding of the sheets P begins. A pre-separating portion  201  attached to the base  20  regulates the forward movement of most of the sheets P, allowing only a few top sheets P to be sent to the nipping portion between the feed roller  28  and separating roller  241 , in which the topmost sheet P is separated from the rest of the sheets P sent to the nipping portion. Then, only the topmost sheet P is conveyed further (fed). 
   As the sheet P reaches the pair of conveyance rollers, more specifically, a conveyance roller  36  and a pinch roller  37 , which will be described later, the pressure plate  21  and separation roller  28  are moved away from their sheet feeding positions by the cam  214  and control cam  25 , respectively. Also, the return lever  22  is returned to the sheet mounting position by the control cam  25 . Further, the sheets P having reached the nipping portion between the feed roller  28  and separation roller  241  are returned to where they were before the feeding. 
   (B) Sheet Conveying Portion 
   The sheet conveying portion  3  is attached to a chassis  11  formed by bending upward certain portions of a piece of metallic plate. The sheet conveying portion  3  comprises a conveyance roller  36  for conveying sheets P, and a PE sensor  32 . The conveyance roller  36  comprises a metallic roller, and minute particles of a ceramic coated on the peripheral surface of the metallic roller, and is attached to the chassis  11 ; lengthwise ends of the metallic roller, which are not coated with the ceramic particles, are supported by a pair of bearings  38 . A sheet P is more reliably conveyed when the conveyance roller  36  is under a certain amount of pressure. Therefore, a conveyance roller tension spring  381  is disposed between the bearings  38  and the lengthwise ends of the conveyance roller  36 , one for one, to keep the conveyance roller  36  under a certain amount of pressure in order to reliably convey a sheet P. 
   The conveyance roller  36  is in contact with a plurality of pinch rollers  37 , which are rotated by the rotation of the conveyance roller  36 . The pinch rollers  37  are held by a pinch roller holder  30 , and are kept pressed upon the conveyance roller  36  by a pair of pinch roller springs  31 . The rotational shaft of the pinch roller holder  30  is borne by the bearing of the chassis  11 , allowing the pinch roller holder  30  to rotate about the rotational shaft. There are disposed a paper guide flapper  33  and platen  34  for guiding a sheet P, at the entrance of the sheet conveying portion  3  from which a sheet P is conveyed. The pinch roller holder  30  is provided with a PE sensor lever  321  for informing the PE sensor  32  of the detection of the leading and trailing ends of a sheet P. The platen  34  is attached to the chassis  11 , being thereby accurately positioned. The paper guide flapper  33  is in contact with the conveyance roller  36 , and is rotatable about the bearing portion  331 . It is accurately positioned by coming in contact with the chassis  11 . 
   The platen  34  is provided with a sheet presser  341  for covering the edge portion of a sheet P, which is on the sheet alignment reference side of the platen  34 . With the provision of the sheet presser  34 , even if a sheet P, the edge portion of which has deformed, a curled sheet P, or the like must be used, the deformed or curled edges are prevented from bending or curling toward the recording head  7 , being therefore prevented from interfering with the recording head  7 . The recording head  7  for forming images based on image formation information is disposed on the downstream side of the conveyance roller  36  in terms of the sheet conveyance direction. 
   After being sent to the sheet conveying portion  3  by the mechanism structured as described above, each sheet P is guided to the nipping portion between the conveyance roller  36  and pinch roller  37 . As the sheet P is conveyed to the nipping portion, the leading end of the sheet P is detected by the PE sensor lever  321 , in order to determine where on the sheet P an image is to be recorded (printing position, image formation position). As the pair of rollers  36  and  37  are rotated by the sheet conveyance motor  35 , the sheet P is conveyed on the platen  34 . The platen  34  is provided with a plurality of ribs which form a virtual surface as the sheet conveyance reference. Not only are these ribs used for controlling the gap between the platen  34  and recording head  7 , but also they control the waving of a recording sheet P; it minimizes the waving of a sheet P, in coordination with the sheet delivery portion, which will be described later. 
   The conveyance roller  36  is driven by transmitting the rotational force of the sheet conveying DC motor  35  to a pulley  361  attached to the shaft of the conveyance roller  36  with the use of a timing belt. The shaft of the conveyance roller  36  is provided with code wheel  362  for detecting the distance by which a sheet P has been conveyed by the conveyance roller  36 . The code wheel is provided with a plurality of markings, which are disposed at a pitch of 150 lpi-300 lpi. The chassis  11  is provided with an encoder sensor for reading the above mentioned markings, which is attached to a portion of the chassis in the adjacencies of the code wheel  362 . 
   The recording means (recording head)  7  is an ink jet recording head, which is structured so that a plurality of ink containers different in the color of the ink therein can be removably attached to the ink jet recording head. Further, the recording head  7  is capable of applying heat to the ink therein with the use of heaters (heating elements) or the like, in accordance with recording data. As the heat is applied to the ink, the ink boils in the film boiling fashion, generating bubbles. As a result, the ink is ejected in the form of an ink droplet from the ejection orifices of the recording head  7  by the pressure changes caused by the growth or contraction of the bubbles. The ejected ink droplets form an image on a sheet P of recording medium. 
   (C) Carriage Portion 
   The carriage portion  5  has a carriage  50  to which the recording head  7  is attached. The carriage  50  is supported by the combination of a guide shaft  52  and guide rail  111  disposed perpendicular to the sheet conveyance direction so that the carriage  50  can be shuttled in the primary scanning direction. The guide rail  111  supports the rearward end of the carriage  50 , doubling as a means for maintaining a proper amount of gap (recording gap) between the recording head  7  and a sheet P. The guide shaft  52  is attached to the chassis  11 , whereas the guide rail  111  is an integral part of the chassis  11 . The portion of the guide rail  111  on which the carriage  50  slides is covered with a thin sheet  53  of SUS or the like, in order to reduce the amount of the sounds which occur as the carriage  50  slides on the guide rail  111 . 
   The carriage  50  is driven by the carriage motor  54  attached to the chassis  11  with the interposition of the timing belt  541 , which is supported and tensioned by an idler pulley  542 . The timing belt  541  and carriage  50  are connected to each other, with the interposition of a rubber damper  55  or the like, in order to reduce the amount of image anomalies by damping the vibrations from the carriage motor  54 , etc. Further, in order to detect the position of the carriage  50 , a code strip  561  having a plurality of markings, the pitch of which is in the range of 150 lpi-300 lpi, is disposed in parallel to the timing belt  541 . Further, an encoder sensor  56  for reading the code strip  561  is attached to the circuit board  92  of the carriage  50 . This carriage circuit board  92  is also provided with a contact  921  for establishing electrical contact with the recording head  7 . Further, the carriage  50  is provided with a flexible circuit board  57  for transmitting head signals from an electrical portion (electrical circuit)  9  to the recording head  7 . 
   In order to fix the recording head  7  as a recording means to the carriage  50 , the carriage  50  is provided with a head catcher  501  for accurately positioning the recording head  7 , and a pressing means (head pressing means)  511  for keeping the recording head  7  immovably attached to the carriage  50  by keeping the recording head  7  pressed on the carriage  50 . This pressing means  511  is attached to a head setting lever  51  so that as the head setting lever  51  is rotated about its rotational axis, the recording head  7  is pressed on the head catcher  501  and circuit board  92  of the carriage  50  by the pressing means  511 . The guide shaft  52  is provided with a pair of eccentric cams  521 , which are attached to the lengthwise ends of the guide shaft  52 . Thus, as a motor  58  for vertically moving the carriage  50  is driven, the driving force therefrom is transmitted to the eccentric cams  521  through a gear train  581 , and vertically moves the guide shaft  52 . The carriage  50  is vertically moved by the vertical movement of the guide shaft  52 , so that an optimal gap is provided between the recording head  7  and a sheet P regardless of the thickness of the sheet P. 
   When recording on a label portion of a small and thick recording medium, for example, a CD-R or the like, a CD print tray  83  is employed. Thus, the carriage  50  is provided with a tray position detection sensor  59  for detecting the marking  834  provided on the CD print tray  83 . The tray position sensor  59  is a reflection type sensor. It emits a beam of light from its light emitting element, and detects the position of the tray  83  by receiving the beam of light reflected by the tray  83 . The sequence for forming an image on a sheet P of recording medium with the use of the recording apparatus structured as described above is as follows. First, a sheet P is conveyed by the pair of rollers (conveyance roller and pinch roller)  36  and  37 , respectively, to the recording area (in terms of sheet conveyance direction). Then, the carriage  50  is moved to the recording (image forming) position (in the direction perpendicular to the sheet conveyance direction), positioning the recording head  7  in a manner to oppose the recording position (image formation position) on the sheet P. Then, the recording head  7  ejects ink toward the sheet P in response to the signals from the electrical portion (electrical circuit)  9 , recording (forming) the image on the sheet P. 
   (Sheet Delivery Portion) 
   The sheet delivery portion  4  comprises: two discharge rollers  40  and  41 ; spur wheels which are kept pressured upon the discharge rollers  40  and  41  in a manner to generate a predetermined amount of contact pressure, and which are rotated by the rotation of the discharge rollers  40  and  41 ; and a gear train for transmitting driving force from the conveyance roller  36  to the discharge rollers  40  and  41  (FIG.  5 ). The discharge rollers  40  and  41  are attached to the platen  34 . The discharge roller  40 , that is, the one on the upstream side in terms of the sheet conveyance direction, comprises a metallic shaft, and a plurality of rubber portions (rubber rollers)  401  fitted around the metallic shaft. The discharge roller  40  is driven by the driving force transmitted from the sheet conveyance roller  36  through a set of idler gears. The discharge roller  41  comprises a shaft made of resin, and a plurality of elastic members  411 , which are made of elastomer or the like, and which are attached to the shaft made of resin. The discharge roller  41  is driven by the driving force transmitted thereto from the discharge roller  40  through a set of idler gears. 
   Each spur wheel  42  comprises: a spur wheel proper, that is, a wheel which is formed of thin plate of SUS, and the peripheral portion of which is provided with a plurality of radial projections; and a resinous portion covering the surface of the spur wheel proper. The spur wheels  42  structured as described above are attached to a spur wheel holder  43 . In this embodiment, the spur wheels  42  are kept pressured upon the discharge rollers  40  and  41  by spur wheel springs  44 , which are coil springs, in the form of a rod, attached to the spur wheel holder  43 . There are two types of spur wheels: those for mainly forwarding a sheet P, and those for mainly preventing a sheet P from floating during an image forming operation. The spur wheels for forwarding a sheet P are positioned so that they oppose the rubber portions (rubber rollers of discharge roller  40  and elastic portions of discharge roller  41 ) of the discharge rollers  40  and  41 . The spur wheels for preventing a sheet P from floating are positioned so that they oppose the portions of the discharge rollers  40  and  41 , where the rubber portions  401  are missing (intervals of rubber portions  401 ). 
   Between the discharge rollers  40  and  41 , a pair of sheet edge supports  45  are provided. The sheet edge supports  45  are for keeping raised the edge portions of a sheet P held by the tips of the rubber portions of the discharge rollers  40  and  41 , in order to prevent the problem that the image on the preceding sheet P is damaged or reduced in quality as the recorded portions of the preceding sheet P are rubbed by the following sheet P. Each sheet edge support  34  comprises: a portion which is made of resin, and to the edge of which a roller  451  is attached; and a sheet edge support spring  452  for applying a predetermined amount of pressure upon the portion made of resin. Thus, the roller  451  is pressed upon a sheet P by the predetermined amount of pressure, supporting the edge of the sheet P while stiffening the sheet P by raising the edge. 
   With the provision of the above described structural arrangement, after the recording (formation) of an image on a sheet P on the carriage portion  5 , the sheet P is nipped by the combination of the discharge rollers  41  and spur wheels  42 , and is conveyed further to be discharged into the delivery tray  46 . The delivery tray  46  comprises a plurality of members, and is collapsible so that it can be stored in the bottom case  99  of the recording apparatus. The delivery tray  46  is to be pulled out when necessary. The delivery tray  46  shown in  FIG. 2  is shaped so that the greater the distance of a given point of the delivery tray  46  from the main assembly of the recording apparatus, the higher the given point, and also so that its lateral edges protrude slightly upward. With the provision of this structural arrangement, not only are the sheets P efficiently accumulated in the delivery tray  46  after their discharge, but also their recorded surfaces are prevented from being rubbed (FIG.  2 ). 
   (E) Recovery Mechanism Portion (Cleaning Portion) 
   The recovery mechanism portion (cleaning portion)  6  comprises: a pump (vacuum pump or the like as a negative pressure generating source)  60  for carrying out the process (cleaning operation) of maintaining or restoring the liquid ejection performance of the recording head  7 ; a cap  61  for protecting the surface of the recording head  7  having the ejection orifices, and preventing the ink from drying at the surface; and a wiping means (blades)  62  for wiping away (removing) the deposits, such as the ink, dust, etc., adhering to the adjacencies of the ejection orifices of the recording head  7 . Further, the recovery mechanism portion  6  is provided with a recovery motor  69  dedicated thereto, and a one-way clutch  691  so that as the recovery motor  69  is rotated in one direction, the pump  60  is operated, whereas as the recovery motor  69  is rotated in the other direction (in reverse), the cap  61  is moved in the direction perpendicular to the surface of the recording head  7  having the ejection orifices, and the blades  62  are made to wipe. 
   The pump  60  in this embodiment comprises two tubes  67  and a pump roller  68 , and the negative pressure is generated as the pump roller  68  is moved in a manner to flatten the two tubes  67 . The vacuum passage (tube or the like) from the cap  61  to the pump  60  is provided with a valve  65 , etc., which are located somewhere between the cap  61  and pump  60 . This vacuum-based recovery means is operated with the cap  61  placed airtightly in contact with the surface of the recording head  7  having the ejection orifices (with the surface capped). As the recovery means is operated, negative pressure is generated in the cap  61 . As a result, foreign substances, for example, the portion of the ink in the recording head  7 , the viscosity of which has increased, bubbles, and dust having settled in the ejection orifices, are suctioned out of the ejection orifices, along with normal ink, by the vacuum. The interior of the cap  61  is provided with an absorbent member  611  for reducing the amount of the ink (residual ink) remaining on the surface of the recording head  7  having the ejection orifices, after the suctioning. Placing the absorbent member  611  in the cap  61 , however, creates the possibility that the ink remaining in the absorbent member  611  will dry up and solidify. Thus, in order to prevent this problem, the vacuum-based recovery means is structured so that the vacuum pump  60  can be idled, that is, it can be operated with the cap  61  open, to suction away the ink remaining in the cap  61 . After being suctioned away by the pump  60 , the waste ink is absorbed by an absorbent member  991  in the bottom case  99  and retained therein. The bottom case  99  will be described later. 
   The series of the various recovery steps carried out by the recovery mechanism portion  6 , that is, the wiping by the blade  62 , placing the cap  61  in contact with the recording head  7  or moving it away from the recording head  7  (step to move cap  61  in the direction perpendicular to the surface of the recording head  7  having the ejection orifices), opening or closing of the valve  65  between the cap  61  and pump  60 , and the like steps, are controlled by the main cam  63 , which comprises a shaft, and a plurality of subsidiary cams; each recovery step is carried out by activating the subsidiary cam or lever corresponding thereto, by the main cam  63 . The attitude of the main cam  63  in terms of its rotational direction (angle of a given point of main cam  63  relative to referential point) can be detected by a position detection sensor  64  such as a photo-interrupter. While the cap  61  is not in contact with the recording head  7  (in the bottom position, in this embodiment), the blades  62  are moved in the direction perpendicular to the primary scanning direction of the carriage  5  to wipe (clean) the surface of the recording head  7  having the ejection orifices. The recovery mechanism portion  6  in this embodiment is provided with a plurality of blades  62  different in function: blades for wiping the adjacencies of the ejection orifices of the recording head  7 , and blades for wiping the entirety of the surface of the recording head  7  having the ejection orifices. Further, the recovery mechanism portion  6  is structured so that as the blades  62  reach the deepest end of their paths, they are placed in contact with a blade cleaner  66 , so that the ink (transfer ink) adhering to the blades  62 , or the like contaminants, are removed to restore the blades  62  in wiping performance. 
   (F) Peripheral Portions 
   The above described functional portions (functional units) inclusive of mechanical portions are integrally disposed in the chassis  11  of the recording apparatus  1 , constituting the main portions of the recording apparatus, whereas the peripheral portions of the recording apparatus  1  are attached to the chassis  11  in a manner to surround these main portions. The essential peripheral portions are the top and bottom cases  98  and  99 , an access cover  97 , a connector cover  96 , and a front cover  95 . There are disposed a pair of delivery tray rails  992  below the bottom case  99 , making it possible for the delivery tray  46  to be collapsed into the bottom case  99 . The front cover  95  is structured so that the sheet discharge opening is kept covered by the front cover  95  when the recording apparatus is not in use. To the top case  98 , the access cover  97  is rotatably attached. The top wall of the top case  98  is provided with an opening, through which an ink container  71 , recording head  7 , etc., can be replaced. Further, the top case  98  is provided with a door switch lever  981  for detecting the opening or closing of the access cover  97 , an LED guide  982  for transmitting the beam of light from an LED or showing the beam of light from the LED, a key switch  983  for activating or deactivating the SW of the electrical portion  6 , which is in a part of the top wall of the top case  98 , etc. 
   Further, the extendable (collapsible) sheet feeding tray  26  comprising a plurality of members is rotatably attached to the top case  98 . Thus, when the sheet feeding portion is not in use, the sheet feeding tray  26  can be collapsed (retracted) so that it can function as the cover for the sheet feeding portion. The top and bottom cases  98  and  99  are attached to the chassis  11 , with the use of elastic fasteners in the form of a claw. The connector portions between the top and bottom cases  98  and  99  are covered with the connector cover  96 . 
   Next, referring to  FIGS. 6-19 , the structure of the portion of the recording apparatus in this embodiment of the present invention, which is for accommodating the CD conveying portion  8 , and the operation for printing (recording) on a CD, will be described in detail.  FIG. 6  is a perspective view of the combination of the recording apparatus, shown in  FIG. 1 , and CD conveyance portion  8 , before and after the attachment of the CD conveyance portion  8  to the recording apparatus, and  FIG. 7  is a perspective view of the CD conveyance portion  8  attachable to the recording apparatus shown in FIG.  1 .  FIG. 8  is a perspective view of the portion of the bottom case  99 , to which the CD conveyance portion  8  is attached, and which detects the CD conveyance portion  8 .  FIG. 9  is a vertical sectional partial view of the combination of the bottom case  99  and CD conveyance portion  8 , showing how the hook  84  of the CD conveyance portion  8  engages with its counterpart of the bottom case  99 , and  FIG. 10  is a perspective view of the CD conveyance portion  8 , before the attachment of the CD conveyance portion  8 , and after the CD conveyance portion was attached and the sliding cover  81  thereof was moved.  FIG. 11  is a vertical sectional partial view of the combination of the bottom case  99  and CD conveyance portion  8 , after the disengagement of the hook  84  of the CD conveyance portion  8  from its counterpart of the bottom case  99 , and  FIG. 12  is a perspective view of the hook, the adjacencies thereof, the CD conveyance portion  8 , and their counterparts of the recording apparatus, showing the state of the arm  85  before and after the sliding cover  81  of the CD conveyance portion was moved. 
     FIG. 13  is a schematic top plan view of the CD conveyance portion  8  for the recording apparatus in the first embodiment of the present invention, showing the means for mathematically determining the area of a CD, across which recording is to be made, and  FIG. 14  is a schematic sectional view of the tray shown in  FIG. 13 , showing the sectional shape of the recording position detecting portion of the tray  83 .  FIG. 15  is a schematic top plan view of the tray  83  shown in FIG.  13  and the tray position detection sensor  59 , showing their various positional relationships, and  FIG. 16  is a perspective view of the combination of the main assembly of the recording apparatus, CD conveyance portion  8 , and tray  83 , after the CD conveyance portion  8  was attached to the main assembly and the tray  83  was inserted into the CD conveyance portion  8  in the main assembly.  FIG. 17  is a vertical sectional view of the connective portion of the bottom case of the recording apparatus and the connective portion of the CD conveying portion, showing how the tray  84  is conveyed through them.  FIG. 18  is a vertical sectional view of the shaft moving mechanism of the recording apparatus, for vertically moving the guide shaft  53  of the carriage  50 , when the carriage  50  is at the lowest position and when the carriage is at the highest position.  FIG. 19  is a partially broken perspective view of the CD conveying portion  8 , showing one of the rollers  811  for keeping the CD conveying portion  8  pressed downward, and the roller  824  for keeping the CD conveying portion laterally pressed. 
   Referring to  FIG. 6 , in order to attach the CD conveyance portion  8  to the bottom case  99  of the recording apparatus, the CD conveyance portion  8  is to be slid straight into the recording apparatus in the direction indicated by an arrow mark Y. As the CD conveyance portion  8  is inserted, a pair of lateral tongues of the tray guide  82  are inserted into a pair of lateral guide rails of the bottom case  99  shown in  FIGS. 8 and 9 , one for one. As a result, the CD conveyance portion  8  becomes accurately positioned relative to the recording apparatus. The tray guide  82  is provided with a pair of rotatable hooks  84 , which are located at the left and right front corners of the tray guide  82  in terms of the direction in which the CD conveyance portion  8  is inserted, and which are kept pressured in one direction. As the CD conveyance portion  8  is slid into the recording apparatus, to a predetermined point, it bumps against a certain part of the recording apparatus, being thereby prevented from being inserted further, and each hook  84  interlocks with the stopper of the corresponding guide rail  993 , preventing the CD conveyance portion  8  from sliding backward. The platen  34  is provided with a tray guide detection sensor  344  for mechanically detecting whether or not the tray guide  82  (CD conveyance portion  8 ) is in a predetermined position in the recording apparatus. Thus, as the tray guide  82  is inserted into the recording apparatus main assembly, a part of the tray guide  82  pushes the tray guide detection sensor  344 , causing the sensor  344  to detect that the CD conveyance portion  8  (tray guide  82 ) has been inserted to the predetermined point in the recording apparatus. 
   Next, referring to  FIGS. 10 and 12 , the sliding cover  81  is to be moved toward the main assembly of the recording apparatus. As the sliding cover  81  is moved, the arms  85  are made to protrude toward the main assembly of the recording apparatus, being thereby inserted between the spur wheel holder  43  and platen  34 , by the movement of the sliding cover  81 . The spur wheel holder  43 , which is holding the spur wheels  42  is attached to the platen  34 , being enabled to vertically move. Further, the spur wheel holder  43  is kept pressured downward by a predetermined amount of force generated by springs. Thus, as the arms  85  are inserted between the spur wheel holder  43  and platen  34 , the spur wheel holder  43  is rotated upward by a predetermined amount. As the spur wheel holder  43  is rotated upward, a space, through which the tray  83 , in which a CD (CD-R or the like) as recording medium is placed, is conveyed, is created between the platen  34  and spur wheel holder  43 . Incidentally, the front end portion of each arm  83  is tapered, forming a slanted portion  851 . Therefore, the arm  85  can be easily inserted between the platen  34  and spur wheel holder  43 . 
   Each arm  85  is structured so that as it is inserted between the platen  34  and spur wheel holder  43 , it becomes locked in the position between the platen  34  and spur wheel holder  43 . Before the arm  85  is made to protrude (advance), it remains loosely fitted in the tray guide  82 . Further, before the sliding of the sliding cover  81  toward the main assembly of the recording apparatus, the opening  821  of the CD conveyance portion  8  remains covered, preventing the tray  83  from being inserted into the CD conveyance portion  8 . The CD conveyance portion  8  is structured so that as the sliding cover  81  is slid toward the main assembly of the recording apparatus, it moves diagonally upward. Therefore, as the sliding cover  81  is slid toward the main assembly, the tray insertion opening  821  is created between the sliding cover  81  and tray guide  82 . In this state, the tray  83  containing a CD can be inserted into the CD conveyance portion  8  through the opening  821  to be accurately positioned relative to the main assembly of the recording apparatus, as shown in FIG.  16 . The above described structural arrangement is for preventing a tray sheet  831  attached to the leading end of the tray  83 , or the spur wheels  42 , from becoming damaged due to the collision between the tray  83  and spur wheels  42  which occurs if the tray  83  is inserted without moving the spur holder  43  upward. 
   Referring to  FIG. 11 , as the sliding cover  81  is pulled out of the main assembly of the recording apparatus while the tray guide  82  is in the proper position in the main assembly, each arm  85  is disengaged from the spur holder  43  by the movement of the sliding cover  81 , and the spur wheel holder  43  and spur wheels  44  descend to their predetermined bottom positions. If an attempt is made to pull out the sliding cover  81  from the main assembly while the tray  83  is in the tray guide  82 , the tray  83  becomes stuck in the opening  821  between the sliding cover  81  and tray guide  82 , preventing thereby the sliding cover  81  from being pulled out further. Therefore, the problem that a recording medium such as a CD-R is damaged by the spur wheels  44  as the spur wheel  44   s  descend while the recording medium is in the main assembly of the image forming apparatus does not occur. 
   Also referring to  FIG. 11 , as the sliding cover  81  is pulled, it causes each hook  84  to disengage from the guide rail  993  of the bottom case  99 , allowing the CD conveyance portion  8  to be removed from the main assembly of the recording apparatus. 
   Referring to  FIG. 13 , the tray  83  in this embodiment of the present invention is made of a piece of resin plate with a thickness of 2 mm-3 mm. The piece of resin plate (tray)  83  is provided with: a CD locking portion  832 ; a tray grip portion  833 , which is to be grasped by an operator when inserting or removing the tray  83 ; a plurality of position detection marks ( FIG. 13  shows three marks:  834   a ,  834   b , and  834   c )  834 ; four CD removal recesses  835  which are to be used by an operator to remove a CD; a tray alignment mark  836 ; a recessed edge portion  837  toward which the lateral pressure roller moves to be freed from the pressure; a media presence (absence) detection mark  838 ; and a tray adaptor type detection mark  838   a  for detecting tray adaptor type. Further, the tray  83  is provided with a tray sheet  81 , which is attached to the leading end of the tray  83 , in terms of the tray insertion direction, in order to assure that the tray  83  is nipped by the combination of the conveyance roller  36  and pinch roller  37 . 
   As for the positions of the position detection marks  834 , two ( 834   a  and  834   b ) are on the leading end side, with respect to the CD locking portion  832 , and one ( 834   c ) is on the opposite side, or the trailing side. Each of the position detection marks  834  is provided with a highly reflective square member, each edge of which is 3 mm-10 mm long. The reflective member is attached by hot stamping. Referring to  FIGS. 13 and 14 , each of the portions of the surface of the piece of resin plate (tray  83 ), to which the reflective member is attached, is surrounded by a groove  839  so that a thin layer of reflective substance can be attached to the piece of resin plate, exactly in the shape of the position detection mark  834 . Referring to  FIG. 14 , the bottom surface of the groove  839  is slanted at a predetermined angle so that if the beam of light emitted from the tray position detection sensor  59  on the carriage  50  is reflected by the areas other than the position detection marks  834 , it does not return to the light receiving portion of the tray position detection sensor  59 . Therefore, the problem that the position of the tray is erroneously detected can be prevented. 
   The reflectance of the position detection marks  834  on the tray  83  in this embodiment is very high as described above, making it unnecessary for the sensors mounted on the carriage  50  to be of a high performance type, and also, eliminating the need for the compensatory process or the like. Thus, not only do the position detection marks  834  reduce cost, but also recording time (printing time). Further, the position detecting method in this embodiment, which employs the detection marks  834 , can detect the CD position more precisely than any of the conventional CD position detecting methods which directly read the edges of the printable area (recordable area) of a CD, even when printing on a colored CD, or a CD, the printable area of which has been already printed. The CD locking portion  832  is provided with a plurality of molded claws, which keep a CD locked in the proper position. When placing a CD in the tray  83 , an operator is to align the center hole of the CD with the CD locking portion  832 . When removing a CD, an operator is to use the opposing two of the CD removal recesses  835  so that the operator can remove the CD by holding the CD by the peripheral edge. Further, the area surrounding the CD locking portion  832  is one step lower than the other areas of the tray  83 , and the media presence (absence) detection mark  838  is on the surface of this lower area. The media presence (absence) detection mark  838  has a hole with a predetermined dimension, made in a piece of hot stamping foil with a predetermined width, and when this hole is detected, it is determined that a recording medium is not present. 
   Referring to  FIG. 13 , as described before, in order to assure that the tray  83  is nipped by the combination of the conveyance roller  36  and pinch roller  37 , the tray  83  is provided with the tray sheet  831 , which is attached to the leading end of the tray  83 , in terms of the tray insertion direction. The tray sheet  831  is a sheet of PET or the like with a thickness of 0.1 mm-0.3 mm. It has a friction coefficient of a predetermined value and a hardness of a predetermined value. Further, the leading end portion of the tray  83  is tapered, forming the tapered portion  830 . Thus, as the tray sheet  831  is nipped by the combination of the conveyance roller  36  and pinch roller  37 , such force that pulls the tray  831  further into the main assembly of the recording apparatus is generated, and the tapered portion  83 , that is, the leading end portion  830 , of the tray  83  lifts the pinch roller  37 , allowing the thick tray  83  to be nipped by the conveyance roller  36  and pinch roller  37  so that the tray  83  is accurately conveyed. The position detection marks  834  are located so that their positions correspond to the intervals of the pinch rollers  37 . Therefore, the position detection marks  834  do not come into contact with the pinch rollers  37 . Therefore, the position detection marks  834  are not damaged across their surfaces. 
   Referring to  FIG. 19 , the tray guide  82 , that is, the CD conveyance portion  8 , is provided with a side pressure roller  824  for keeping the tray  83 , shown in  FIG. 13 , pressed against a positional reference portion  823 . More specifically, the roller  824  is kept pressured by the predetermined amount of pressure generated by a spring  825 , keeping thereby the tray  83  pressed against the positional reference portion  823  by the predetermined amount of pressure. As a result, the tray  83  is kept accurately positioned in the tray guide  82 . The side pressure roller  824  keeps pressing on the lateral surface of the tray  83  until the tray  83  is inserted by an operator to a predetermined point, beyond which the side pressure roller  824  does not press on the lateral surface of the tray  83 , because, beyond this point, the side pressure roller  824  faces the recessed edge portion of the lateral surface of the tray  83  (FIG.  13 ). This structural arrangement is for preventing the tray  83  from being subjected to an excessive amount of back tension or the like, in order to prevent the accuracy with which the tray  83  is conveyed, from being reduced. 
   Also referring to  FIG. 19 , the sliding cover  81  is provided with a pair of pressure rollers  811 , that is, the left and right pressure rollers  811 , which keep the tray  83  pressed upon the discharge roller  41 , by being kept pressured by the predetermined amount of pressure generated by roller springs  812 . As a result, the force for conveying the tray  83  is generated. The tray  83  can be conveyed by this tray conveying force from the position in which the tray  83  is set at the beginning of a recording (printing) operation, to the nipping portion formed by the conveyance roller  36  and pinch roller  37 . Further, the tray  83  can be conveyed by this tray conveying force to a predetermined point, at which the operator can take out the tray  83 . The tray guide  82  and tray  83  are structured so that the position detection marks  834  and pressure rollers  811  do not coincide in position, preventing thereby the position detection marks  834  from coming into contact with the pressure roller  811  and being damaged across their surfaces by the pressure roller  811 . After the tray  83  is conveyed outward to the above mentioned point, the tray  83  can be pulled out of the tray guide  82 . Then, the operator can utilize the CD removal recesses to remove the CD in the tray  83  by holding the CD by its peripheral edge. 
   Next, the process of recording on a CD with the use of the recording apparatus structured as described will be described. First, the CD conveyance portion  8  is to be slid straight into the bottom case  99  of the main assembly of the recording apparatus  1 . As the CD conveyance portion  8  is inserted, it is detected by the tray guide detection sensor  344  ( FIG. 8 ) that the tray guide  82  has just been inserted into the main assembly of the recording apparatus. Next, the sliding cover  81  is to be moved toward the recording apparatus main assembly. As the sliding cover  81  is moved, each of the two arms  85  is made to protrude toward the recording apparatus main assembly by the movement of the sliding cover  81 , as shown in  FIG. 10 , and moves into the interface between the spur wheel holder  43  and platen  34 , moving the spur wheel holder  43  upward by the predetermined amount. 
   Since the sliding cover  81  is structured so that as it is pushed toward the recording apparatus main assembly, it moves diagonally upward toward the recording apparatus main assembly, the opening  821  ( FIG. 6 ) is created between the sliding cover  81  and tray guide  82 . Therefore, the operator can insert the tray  83 , which contains a CD, into the tray guide  82 , to the predetermined point, as shown in FIG.  16 . More specifically, a CD is to be locked to the tray  83  with the use of the CD locking portion  832  ( FIG. 32 ) after being placed in the tray  83 . The operator is to hold the tray  83  by the grip portion  833 , and insert the tray  83  into the tray guide  82  until the tray alignment marks  836  on the tray ( FIGS. 13 and 16 ) align with the tray alignment marks  826  on the tray guide (FIG.  16 ). 
   As recording signals (print signals, image formation signals) are sent from a host while the tray  83 , in which the CD is present, is in the above described position, an actual recording operation (printing operation) begins. That is, first, the conveyance roller  36 , discharge roller  40  and discharge roller  41  are rotated in reverse, as shown in FIG.  17 . As described before, the force for conveying the tray  83  is generated by pressing the tray  83  upon the discharge rollers  40  and  41  by the predetermined pressure generated by the pressure roller  811  ( FIG. 19 ) and pressure roller  812 . Therefore, as the discharge rollers  40  and  41  are rotated in reverse, the tray  83  is conveyed inward of the recording apparatus. Then, as the tray sheet  831  ( FIG. 13 ) located at the leading end of the tray  83  is nipped between the conveyance roller  36  and pinch roller  37 , pulling the tray  83  further inward of the recording apparatus; the successive conveyance force of the predetermined value is generated. As a result, the tapered portion  830 , that is, the leading end portion, of the tray  83  is made to enter between the conveyance roller  36  and pinch roller  37  while lifting the pinch roller  37 . Consequently, the tray  83  becomes sandwiched by the conveyance roller  36  and pinch roller  37 . 
   Next, the carriage  50  on which the recording head  7  is riding moves from its home position to its recording range (printing range) to detect the tray  83 . Prior to this movement of the carriage  50 , the carriage motor  58  ( FIG. 3 ) for vertically moving the carriage  50  moves the guide shaft  52  upward, creating the optimal gap between the recording head  7  and tray  83  (between head and sheet), as shown in FIG.  18 . Then, the recording (printing) position on the CD is calculated using the means for calculating the recording position on the CD on the tray  83 , shown in  FIG. 13 , in the first embodiment of the present invention, and following the steps shown in FIG.  15 . More specifically, first, referring to FIGS.  15 ( a ) and  15 ( b ), the carriage  50  is stopped as the tray position detection sensor  59  on the carriage  50  aligns with the position detection mark  834   a  ( FIG. 13 ) of the tray  83 . Then, the position of the top edge (leading edge) of the position detection mark  834   a  by conveying the tray  83 . Then, the position of the bottom edge (trailing edge) of the position detection mark  834   a  is detected by further conveying the tray  83 . 
   Next, referring to FIG.  15 ( c ), the tray  83  is moved backward so that the tray position detection sensor  59 , as a tray position detecting means, on the carriage  50  is roughly aligned with the center of the position detection mark  834   a  of the tray  83 . Then, the carriage  50  is moved left- and rightward to detect the positions of the right and left edges of the position detection mark  834   a , as means to be detected for position detection. These steps make it possible to calculate the center position  834   ac  ( FIG. 13 ) of the position detection mark  834   a , and with reference to this center position  834   ac , the recording position (printing position) of the CD in the tray  83  can be accurately calculated. In this embodiment, the position of the tray  83  itself is detected as described above, compared to any of the conventional systems which rely on only mechanical accuracy, that is, without actually detecting the recording position. Therefore, it is possible to eliminate the problem that, because of the effects of component tolerance, tray condition, etc., recording is made (image is printed) on a CD, across the area offset from the intended recording area. 
   After the detection of the position (center position  834   ac ) of the position detection mark  834   a  as the means, on the tray  83 , to be detected for position detection, the carriage  50  is moved, as shown in FIG.  15 ( d ), to detect the position detection mark  834   b  as the means, on the tray  83 , to be detected for position detection. The left and right edges of this position detection mark  384   b  are detected to confirm that the position detection mark  834   a  detected in the prior detection step is not the wrong one. The reason for carrying out this operation is as follows. That is, if the tray  83  is inserted beyond the normal position, as shown in FIG.  15 ( e ), the position detection mark  834   c  is detected instead of the position detection mark  834   a . In such a case, the attempt to detect the position detection mark  834   b  will fail, proving that the detected position detection mark is not the position detection mark  834   a.    
   After the detection of the position of the tray  83 , the tray  83  is conveyed in the normal tray conveyance direction so that the tray position sensor  59  as the tray position detecting means of the carriage  50  aligns with the recording medium presence (absence) detection mark  838  ( FIG. 13 ) as the means, on the tray  83 , to be detected, as shown in FIG.  15 ( f ). Then, the edges of the hole of the recording medium presence (absence) detection mark  838  are detected, and if the distance between the two edges matches the predetermined hole width, it is determined that no CD is in the tray  38 . Then, the recording operation (printing operation) is interrupted, and the tray  83  is moved outward to a predetermined point. Then, an error message is displayed. On the other hand, if the recording medium presence (absence) detection mark  838  could not be detected, it is determined that a CD is in the proper position in the tray  83 , and the recording operation is allowed to proceed. After the completion of the above described initial operation sequence, the tray  83  is conveyed deeper into the recording apparatus (printer or the like), to the predetermined position in which recording can be made (images can be printed) across the entirety of the recordable (printable) area of the Cd. Then, the recording (printing) begins in accordance with the recording data sent from the host. Incidentally, the usage of one of the so-called multi-pass recording methods which form images by scanning multiple times a given area of a recording medium reduces the extent of inconsistency, in terms of the recording medium conveyance direction, by which images are recorded, and which is related to the accuracy with which a CD is conveyed and the accuracy with which the ink droplets from the recording head  7  land on the recordable area of the CD. 
   After the completion of the recording (printing) operation, the tray  83  is conveyed to the position in the tray guide  82 , into which the operator placed the tray  83  before the beginning of the actual printing operation. From this position, the operator can pull out the tray  83 , which now contains the CD, across the recordable area of which recording has been made. After the removal of the CD, the sliding cover  81  is to be pulled toward the front (in the direction to move the sliding cover away from the recording apparatus main assembly). As the sliding cover  81  is pulled, each arm  85  is released from the spur wheel holder  43 , and each hook  84  is released from the bottom case  99 , allowing the CD conveyance portion  8  to be removed (freed) from the recording apparatus main assembly. As is evident from the above description of the recording apparatus in the first embodiment of the present invention, the recording apparatus in this embodiment is capable of precisely recording (printing) on a CD, and yet, is simple in structure and operation, and easy to operate. 
   (Embodiment 2) 
     FIG. 20  is a schematic top plan view of the tray usable with the CD conveyance portion  8  for the recording apparatus, in the second embodiment of the present invention, showing the means for calculating the recording position on a CD. In the first embodiment described above, the recording position (printing position) on a CD in the proper position in the tray  83  is obtained by calculating the center position  834   ac  of the position detection mark  834   a , and the other position detection marks  834   b  and  834   c  were used as confirmation marks. However, the recording position on a CD may be calculated by detecting a plurality of position detection marks as is in this embodiment. 
   To describe in more detail, in the case of the tray  83  in the second embodiment shown in  FIG. 20 , both the position detection marks  834   a  and  384   b  are provided with center positions  834   ac  and  834   bc , respectively, similar to the center position  834   ac  in the first embodiment. Chosen, in this embodiment, as the referential point for calculating the recording position on a CD in the tray  83  is such a point of the tray  83  that is a predetermined distance C toward the upstream direction, in terms of the tray insertion direction, from the point, on the line connecting the center positions  834   ac  and  834   bc  of the position detection marks  834   a  and  834   b , which is a distance A from the center positions  834   ac  and a distance B from the center position  834   bc . Otherwise, the second embodiment, the tray  83  in which is shown in  FIG. 20 , is practically the same in structure as the first embodiment. The structural arrangement in this embodiment makes it possible to compensate even if the tray  83  moves askew. Therefore, it makes it possible to more accurately record (print) on a CD in terms of position. 
   (Embodiment 3) 
     FIG. 21  is a schematic top plan view of the tray  83  usable with the CD conveyance portion  8  for the recording apparatus, in the third embodiment of the present invention, showing the means for calculating the recording position on a CD. In the preceding embodiments (first and second embodiments) described above, three position detection marks  834  were provided as the means for detecting the tray  83 . The number of the position detection marks  834 , however, may be two as shown in FIG.  21 . One of the position detection marks  834 , which in this embodiment is the position detection mark  834   a , is rectangular, whereas the other mark, or the position detection mark  834   c , is square as those in the preceding embodiments. Therefore, whether the position detection mark  834   a  is detected or the position detection mark  834   c , its identity is clear, making unnecessary the operation carried out in the preceding embodiments to detect the position detection mark  834   b . Therefore, the throughput of this embodiment is greater than those of the preceding embodiments. Otherwise, the third embodiment, the tray  83  in which is shown in  FIG. 21 , is practically the same in structure and function as the preceding embodiments. 
   (Embodiment 4) 
     FIG. 22  is a schematic top plan view of the tray  83  usable with the CD conveyance portion  8  for the recording apparatus, in the fourth embodiment of the present invention, showing the means for calculating the recording position on a CD. In the second embodiment described above, such a point of the tray  83  that is a predetermined distance C perpendicularly in the upstream direction, in terms of the tray insertion direction, from the central point of the line connecting the center positions  834   ac  and  834   bc  of the position detection marks  834   a  and  834   b  was chosen as the referential point for calculating the recording position on a CD in the tray  83 . Instead, however, the position detection marks  834   a  and  834   b , as the means to be used for calculating the recording position on a CD may be disposed as shown in  FIG. 22 , in which the position detection marks  834   a  and  834   b  are at the right front corner and left rear corner, respectively, in terms of the tray insertion direction, so that the line connecting the two marks  834   a  and  834   b  becomes diagonal relative to the tray insertion direction. 
   Also referring to  FIG. 22 , one of the position detection marks, which in this embodiment is the position detection mark  834   a , is rectangular, the intersection of the diagonals of which constitutes the center position  834   ac , whereas the other position detection mark, which in this embodiment is the position detection mark  834   b , is square, and the intersection of the diagonals of which constitutes the center position  834   bc . Further, the center of the CD locking portion  832  coincides with the center of the line connecting the center position  834   ac  and  834   bc ; in other words, the center of the CD locking portion  832  coincides with the center of the recordable area of a CD. Otherwise, the fourth embodiment, the tray in which is shown in  FIG. 22 , is practically the same in structure and function as the second embodiment. The structural arrangement in the fourth embodiment also can align the center of the recordable area of a CD with the center of the DC locking portion. In addition, the structural arrangement in this embodiment makes it possible to compensate even if the tray  83  moves askew. Therefore, it is possible to more accurately record (print) on a CD in terms of position. Otherwise, the fourth embodiment, the tray in which is shown in  FIG. 22 , is practically the same in structure and function as the preceding embodiments. 
   (Embodiment 5) 
     FIG. 23  is a schematic top plan view of the tray  83  usable with the CD conveyance portion  8  for the recording apparatus, in the fifth embodiment of the present invention, showing the means for calculating the recording position on a CD. In the preceding embodiments described above, the means (position detection mark)  834  to be detected for position detection, are disposed so that they will be within the recordable range of a CD in the tray  83 , in terms of the direction perpendicular to the tray conveyance direction. In this embodiment, however, they are disposed outside the recordable range of a CD, as shown in FIG.  23 . More specifically, the three position detection marks  834   a ,  834   b , and  834   c  are disposed outside the thick dotted lines, in  FIG. 23 , which border the recordable (printable) range of a CD in the tray  83 , in terms of the direction perpendicular to the tray conveyance direction, and which extend in the tray conveyance direction. This positional arrangement prevents the path of the tray position detecting means (tray position detection sensor)  59  on the carriage  50  from overlapping with a CD in the tray  83 . In other words, the tray position detecting means  59  reads only the surface of the tray  83 . Therefore, the possibility that erroneous detections will occur because the recordable area of a CD already has a recorded (printed) image, is eliminated. Otherwise, the fifth embodiment, the tray in which is shown in  FIG. 23 , is practically the same in structure and function as the preceding embodiments, and therefore, is capable of precisely calculating the recording position on a CD to accurately record (print) on a CD in terms of position. 
   The preceding embodiments (Embodiments 1-5) described above offer the following functions and effects: 
   The position of a CD is directly detected. Therefore, the component tolerance, tray condition, or the like does not cause an image to be printed on a wrong area of a CD. Further, even if the tray moves askew or in the like fashion, compensation can be made to record on the normal position. 
   The means, on the tray, to be detected are high in reflectance. Therefore, it is unnecessary to employ high performance sensors, and the need for compensatory processes is smaller. Therefore, it is possible to provide recording apparatuses which are inexpensive and are shorter in printing time, compared to the recording apparatuses in accordance with the prior arts. Further, the printing position of a CD can be accurately detected even if the CD is colored or even if the CD already has a printed image. 
   (Embodiment 6) 
   In the first embodiment described above, both of the lateral edges of the hole of the recording medium presence (absence) detection mark  838  were read by the tray position detection sensor  59  attached to the carriage  50 . Then, if the edges were detected, it was determined that no CD was present, and if the edges were not detected, it was determined that a CD was present. This arrangement in the first embodiment may be modified so that not only can the presence (absence) of a CD be detected, but also the type of a CD in the tray  83  can be detected, as in this sixth embodiment.  FIG. 24  is a schematic plan view of the tray adaptor  86  to be attached to tray  83  usable with the recording apparatus, in the sixth embodiment of the present invention. The tray adaptor  86  is used when using the tray  83  shown in  FIG. 13  to record on, for example, a CD with a diameter of 8 cm, or a card type CD, in other words, a recordable medium (CD) other than an ordinary CD, that is, a CD with a diameter of 12 cm. In  FIG. 13 , which shows the tray  83  in the first embodiment, the tray  83  has a recess in which a 12 cm CD is set, and the bottom surface of which is one step lower than the surrounding area, more specifically, lower by such a step that as a 12 cm CD is placed in the recess, the top surface of the CD becomes level with the surrounding area. However, if an 8 cm CD is set in this recess, a donut-like recess, the bottom surface of which is lower by the above described amount, is created, with the peripheral edge of the 8 cm CD constituting the top edge of the recess, because the 8 cm CD is smaller by 2 cm in radius. Thus, if the tray  83  containing an 8 cm CD is conveyed through the recording apparatus, the pinch roller  37  has to climb to the peripheral edge of the 8 cm CD after descending to the bottom of the recess around the 8 cm CD. Therefore, the tray  83  is less precisely conveyed. 
   Thus, in this embodiment, when printing on an 8 cm CD, a tray adaptor  86  shown in  FIG. 24  is placed in the tray  83  shown in  FIG. 13 , and the 8 cm CD is placed in the tray adaptor  86 , in order to prevent the periphery of the 8 cm CD from creating a step. There are various tray adaptors  86  different in the type of a CD they accommodate. They have a tray adaptor type detection hole  861 , the size of which varies depending on the tray type. Further, the tray adaptor  86  is provided with projections  862  and  863  for accurately positioning the tray adaptor  86 , in terms of its orientation relative to the tray  83 . The tray adaptor  86  is also provided with an opening  864 , in which an 8 cm CD or card-shaped CD is placed, and which is centrally located relative to the tray adaptor  86 . 
     FIG. 25  is a schematic top plan view of the combination of the tray  83  usable with the recording apparatus, in the sixth embodiment of the present invention, and the tray adaptor  86 , shown in  FIG. 24 , in the tray  83 .  FIG. 26  is a schematic top plan view of the combination of the tray  83  usable with the recording apparatus, in the sixth embodiment of the present invention, the tray adaptor  86 , shown in  FIG. 24 , fitted in the tray  83 , and the 8 cm CD in the tray  83  fitted with the adaptor  86 .  FIG. 27  is a schematic plan view of the combination of the tray  83  usable with the recording apparatus, in the sixth embodiment of the present invention, the tray adaptor  86 , shown in  FIG. 24 , fitted in the tray  83 , and the card-type CD 8 cm in the tray  83  fitted with the adaptor  86 . Referring to  FIG. 25 , the projections  862  and  863  for accurately positioning the tray adaptor  86  in terms of its orientation relative to the tray  83  are fitted in the pair of CD removal recesses  835  of the tray  83 . As for the tray adaptor type detection hole  861 , it is located so that when the tray adaptor  86  is in the tray  83 , it aligns with the tray adaptor type detection mark  838   a  ( FIG. 13 ) on the tray  83 . Thus, in  FIG. 25 , the tray adaptor type detection mark  838   a  is visible through the tray adaptor type detection hole  861 . Further, the recording medium presence (absence) detection mark  838  of the tray  83  is visible through the opening  864  in which a CD fits. 
   Referring to  FIG. 26 , as an 8 cm CD  87  is fitted into the opening  864  of the tray adaptor  86  fitted in the tray  83 , the recording medium presence (absence) detection mark  838  is hidden by the 8 cm CD  87 . Therefore, even if the above described recording medium presence (absence) detection operation is carried out, the edges of the recording medium presence (absence) detection mark  838  cannot be detected; it is determined that a medium is present. Next referring to  FIG. 27 , after the fitting of a card-type CD  88  into the opening  864  of the tray adaptor  86  fitted in the tray  83 , one half of the recording medium presence (absence) detection mark  838  is hidden by the CD medium (card-type CD  88 ), and the other half is visible through a part of the opening  864  in which a CD (recording medium) fits. At this time, the operation for detecting the medium type and the operation for detecting the presence or absence of a recording medium will be described. As in the description of the first embodiment, various position detection marks  834  on the tray  83  are detected by the tray position detection sensor  59  on the carriage  50 . In this case, before the recording medium presence (absence) detection operation is carried out, the carriage  50  is moved in the direction of an arrow mark AA in  FIG. 27  to read the width of the tray adaptor type detection hole  861 . Then, the tray adaptor type is identified based on the detected width. For example, if the detected width of the tray adaptor type detection hole  861  of a given tray adaptor is X, the tray adaptor is the one capable of accommodating both an 8 cm CD and a card-type CD. 
   Next, the carriage  50  is moved in the direction of an arrow mark AB in  FIG. 27  to detect the recording medium presence (absence) detection mark  838 . If the edges of the recording medium presence (absence) detection mark  838  are detected, it is determined that a card-type CD is in the tray adaptor  86  in the tray  83 , or no recording medium is in the tray adaptor  86  in the tray  83 . Then, the carriage  50  is moved in the direction of an arrow mark AC in  FIG. 27  to detect the recording medium presence (absence) detection mark  838 . If the edges of the recording medium presence (absence) detection mark  838  are not detected, it is determined that a card-type CD is in the tray adaptor  86  in the tray  83 , whereas if the edges of the recording medium presence (absence) detection mark  838  are detected, it is determined that no recording medium is in the tray adaptor  86  in the tray  83 . In other words, in this embodiment, the type of the tray adaptor  86  is first detected, and then, two areas of the recording medium presence (absence) detection mark  838  are read, as described above. Therefore, it is possible to determine the type of the recording medium in the tray adaptor capable of accommodating two types of recording media. Otherwise, the sixth embodiment, the tray  83  and tray adaptor  86  of which are shown in  FIGS. 24-27 , is the same in structure and function as the preceding embodiments. In other words, the sixth embodiment of the present invention can provide a recording apparatus which is simple in structure, low in cost, and yet, reliably detect the presence (absence) of a recording medium, such as a CD, or the type of a recording medium, when recording on the recording medium with the use of a tray. 
   In the above described first to sixth embodiments, only one recording medium presence (absence) detection mark  838  is provided. These embodiments, however, are not intended to limit the scope of the present invention. For example, a plurality of recording medium presence (absence) detection marks may be provided as in the seventh embodiment, which will be described next. 
   (Embodiment 7) 
     FIG. 28  is a schematic top plan view of the tray  83  usable with the CD conveyance portion  8  for the recording apparatus, in the seventh embodiment of the present invention, showing the means for calculating the recording position on a CD. The tray  83  in  FIG. 28  is provided with a total of two recording medium presence (absence) detection marks, that is, recording medium presence (absence) detection mark  838  and recording medium presence (absence) detection mark  838   e  which are different in position. This arrangement is made to deal with CD media (recording medium) having a recorded image (printed image) prior to the recording thereon. If a CD, the recordable surface of which has a pre-recorded image virtually similar in shape to the recording medium presence (absence) detection mark  838  of the tray  83 , is placed in the tray  83 , it is possible, in spite of the presence of the CD in the tray  83 , that it will be determined that no CD is in the tray  83 . Thus, the plurality of recording medium presence (absence) detection marks  838  are provided to prevent this type of erroneous detection. Although the tray  83  in  FIG. 28  is provided with two recording medium presence (absence) detection marks  838  different in position, the number of recording medium presence (absence) detection marks  838  may be three or more. Further, although the two recording medium presence (absence) detection marks  838  of the tray  83  in  FIG. 28  are the same in shape, they may be different in shape. Moreover, when providing the tray  83  with three or more recording medium presence (absence) detection marks  838  different in position, all, or some, of them may be different or identical in shape. 
   The seventh embodiment, the tray  83  of which is shown in  FIG. 28 , is different from the preceding embodiments in the above described feature. Otherwise, it is practically the same in structure and function as the preceding embodiments. In other words, this embodiment also can provide a recording apparatus which is simple in structure, low in cost, and yet, reliably detect the presence (absence) of a recording medium, such as a CD, or the type of a recording medium, when recording on the recording medium with the use of a tray, as can the preceding embodiments. 
   (Embodiment 8) 
   In the first, sixth, and seventh embodiments of the present invention, the recording medium presence (absence) detection mark  838  and tray adaptor type detection mark  838   a  were on the tray  83 . This arrangement, however, was not intended to limit the scope of the present invention. For example, these marks may be placed on the tray adaptor  86  as in the eighth embodiment, which will be described next.  FIG. 29  is a schematic top plan view of the tray adaptor  86  to be fitted in the tray  83  for the recording apparatus, in the eighth embodiment of the present invention. In the eighth embodiment, the tray adaptor  86  of which is shown in  FIG. 29 , a tray adaptor type detection mark  865  for detecting the tray adaptor type, and a recording medium presence (absence) detection mark  866 , are on the tray adaptor  86 . 
   The recording medium presence (absence) detection mark  866  is a piece of highly reflective tape, for example, thin film of PET or the like, and is pasted to the tray adaptor  86  so that it does not interfere with the placement of a recording medium. The number of the locations to which the recording medium presence (absence) detection mark  866  is attached does not need to be limited to one; two or more of these marks may be attached to two or more locations, one for one. The eighth embodiment, the tray  83  of which is shown in  FIG. 29 , is different from the preceding embodiments in the above described feature. Otherwise, it is practically the same in structure and function as the preceding embodiments. In other words, this embodiment also can provide a recording apparatus which is simple in structure, low in cost, and yet, reliably detect the presence (absence) of a recording medium, such as a CD, or the type of a recording medium, when recording on the recording medium with the use of a tray, as can the preceding embodiments. 
   (Embodiment 9) 
     FIG. 30  is a schematic top plan view of the tray as a recording medium supporting means for the recording apparatus, in the ninth embodiment of the present invention, and  FIG. 31  is a schematic top plan view of the tray adaptor mountable in the tray shown in FIG.  30 .  FIG. 32  is a perspective view, as seen from the top front side, of the combination of the main assembly of the recording apparatus, and the CD conveyance portion in the main assembly, in the ninth embodiment of the present invention, and  FIG. 33  is a perspective view, as seen from the top front side, of the combination of the main assembly of the recording apparatus, CD conveyance portion in the main assembly, and tray, in the ninth embodiment of the present invention, showing how the tray, which is holding a CD as a recordable medium, is inserted into the CD conveyance portion in the state shown in FIG.  32 .  FIG. 34  is a perspective view of the connective portion on the main assembly side of the recording apparatus shown in  FIG. 32 , which interlocks with the CD conveyance portion, and  FIG. 35  is a vertical sectional view of the CD conveyance portion shown in FIG.  35 . 
     FIG. 36  is a vertical sectional view of the connective portion of the main assembly of the recording apparatus, and the connective portion of the CD conveyance portion in the main assembly, showing the structures thereof, and  FIG. 37  is a vertical sectional view of the connective portion of the main assembly of the recording apparatus, and the connective portion of the CD conveying portion, showing how the CD conveying portion is connected to the main assembly of the recording apparatus.  FIG. 38  is a partially broken perspective view, as seen from the top front side, of the combination of the recording apparatus, the tray in the main assembly of the recording apparatus, and a CD in the tray, in the ninth embodiment of the present invention, and  FIG. 39  is an enlarged perspective view, as seen from the top left front side, of the tray in the recording apparatus shown in  FIG. 38 , and a CD in the tray.  FIG. 40  is a vertical sectional view of the CD disposed in the main assembly of the recording apparatus, and its adjacencies, as shown in  FIG. 39 , and  FIG. 41  is a vertical section view of the CD disposed in the main assembly of the recording apparatus, shown in  FIG. 39 , and ready to be recorded, and its adjacencies.  FIG. 42  is a partially broken top plan view of the recording apparatus shown in  FIG. 41 , showing the tray and a CD in the tray, after the completion of the recording on the CD, and  FIG. 51  is a schematic top plan view of one of the variations of the tray adaptor mountable in the tray used with the recording apparatus, in any of the preceding embodiments of the present invention. 
   Next, the recording apparatus in the ninth embodiment will be described with reference to  FIGS. 32-42 . The bottom case  99 , sliding cover  102 , and tray guide  103  of the recording apparatus are symmetrical with respect to their center lines parallel to the recording medium conveyance direction. The tray guide  103  has a pair of hooks  104  and a pair of arms  105 , which are attached to the left and right sides of the tray guide  103 , respectively. Referring to  FIGS. 32 and 33 , as an operator pushes the CD conveyance portion  101  so that the CD conveyance portion  101  slides straight into the recording apparatus main assembly in the direction of an arrow mark Y in  FIG. 32 , the CD conveyance portion  101  is inserted into the bottom case  99 . Then, the sliding cover  102  is to be moved toward the recording apparatus main assembly. As the sliding cover  102  is moved, an opening  102   a  appears on the front side, allowing the operator to insert the tray  106 , which is holding a CD, into a predetermined position in the CD conveyance portion  101  to start a recording (printing) operation. The tray guide  103 , which will be described later in more detail, is provided with a plurality of ribs  103   f   1 - 103   f   5 , which are on the bottom surface of the slot into which the tray  106  is inserted. The provision of the ribs  103   f   1 - 103   f   5 , which support the tray  106 , reduces the contact area between the bottom surface of the slot and the tray  106 , reducing thereby the friction between the CD conveyance portion  101  and tray  106 . In other words, the provision of the ribs  103   f   1 - 103   f   5  contributes to the improvement in the tray conveyance. 
   Referring to  FIGS. 32-42 , the bottom case  99  is provided with a pair of projections  99   a , which fit in the grooves  103   a  ( FIG. 35 ) of the tray guide  103  as a supporting member for supporting the tray  106 . The tray  106  will be described later. Referring to  FIGS. 35 and 36 , the tray guide  103  has a pair of hooks  104 , which are formed of resin. Each hook  104  is supported by a shaft  103   b  so that it can be rotated about the shaft  103   b . The shaft  104  is fitted in the hole  104   a  of the tray guide  103 . The hook  104  is attached to the tray guide  103  by inserting the shaft  103   b  through the hole  104   a  of the hook  104 , from the direction perpendicular to the side walls of the tray guide  103 . When attaching the hook  104  in the above described manner, the flange portion  104   f  of the hook  104  comes into contact with the elastic rib  103   g  of the tray guide  103 . However, the portion  103   h  of the elastic rib  103   g , which comes into contact with the flange portion  104   f , is tapered. Therefore, the flange portion  104   f  slides on the surface of the tapered portion of the portion  103   h  of the elastic rib  103   g , while causing the portion  103   h  to rotate in the direction of an arrow mark c. As a result, the hook  104  is allowed to settle in a predetermined position. 
   The contact portion  103  returns to the original location due to its resiliency, and remains in contact with the flange portion  104   f , preventing the hook  104  from slipping out in the axial direction of the shaft  103   b . The hook  104  is also provided with a thin portion  104   c , like a plate spring, which is on the side opposite to the claw portion  104   b , with respect to the hole  104   a . The hook  104  is attached to the tray guide  103  so that this spring-like portion  104   c  is kept pressed upon the shaft  103   c  of the tray guide  103 . Therefore, the claw portion  104   b  is kept pressured toward the projection  99   a  of the bottom case  99 , by the resiliency of the spring-like portion  104   c  of the hook  104 . Referring to  FIGS. 32 ,  35  and  36 , as the CD conveyance portion  101  is slid in the direction of an arrow mark Y (FIG.  32 ), the claw portion  104   b  of the hook  104  drops into the slot  99   b  ( FIGS. 32 and 36 ) of the projection  99   a . As a result, the CD conveyance portion  101  is accurately positioned relative to the recording apparatus main assembly. The groove  103   a  of the tray guide  103  is wider across the entrance portion  103   a   1 ; in other words, it has a slanted surface  103   a   2 , allowing the projection  99   a  of the bottom case to smoothly enter the groove  103   a.    
   When the hook  4  interlocks with the projection  99   a , the hook  104  comes into contact with the tip  99   a   1  of the projection  99   a . However, the hook  104  is provided with the slanted portion  104   e . Therefore, as the tray guide  103  is pushed, the hook  104  rides over the tip  99   a   1  while being rotated by the tip  99   a   1  in the direction of the arrow mark a, and then, as soon as the claw portion  104   b  of the hook rides over the tip  99   a   1 , it is made to snap into the slot  99   b  by the resiliency of the spring-like thin portion  104   c , and the tip  99   a   1  of the bottom case  99  comes into contact with the surface  103   i  of the tray guide  103 . As a result, the tray guide  103  is accurately positioned relative to the recording apparatus main assembly in terms of the direction of the arrow mark Y, in which the CD conveyance portion  101  is conveyed. Incidentally, the hook  104  is desired to be formed of a slippery substance, for example, polyacetal. The tray guide  103  is also provided with a pair of guiding grooves  103   d , in which the pair of arms  105  slidably fit, one for one. Each arm  105  is provided with a boss  105   b , which fits in the groove  102   d  located on the back side of the sliding cover  102 . The sliding cover  102  is provided with a pair of bosses  102   b  and  102   c , which slidably fit in the pair of guiding grooves  103   e  of the tray guide  103 . When the sliding cover  102  is moved in the direction of an arrow mark b, the positional relationship of the sliding cover  102  relative to the tray guide  103  is controlled by the pair of bosses  102   b  and  102   c , and the pair of the guiding grooves  103   e.    
   To the sliding cover  102 , the above described pair of arms  105  are connected so that as the sliding cover  102  is moved in the direction of the arrow mark b, the arms  105  are horizontally moved by the movement of the sliding cover  102 . Thus, as the sliding cover  102  is moved toward the recording apparatus main assembly, each arm  105  protrudes inward of the recording apparatus main assembly, as shown in  FIG. 37 , inserts itself between the platen  34 , and the spur wheel base  34  which rotatably supports the spur wheels  42  and  42   a , and moves the spur base upward. As a result, a space large enough for the tray  106  to be passed through is formed between the platen  34  and spur wheel base  43 . At the same time, the arms  105  enters between the platen  34  and spur wheel base  42 ; the tapered end portion  105   a  of the arm  105  makes it possible for the arm  105  to smoothly enter between the platen  34  and spur wheel base  42 . Further, when the tray guide 103  is in the recording apparatus main assembly and the sliding cover  102  is open, the arm  105  remains between the platen  34  and spur wheel base  42 , being fixed in position, whereas when the arm  105  is in its retracted position in the tray guide  103 , it remains loose relative to the tray guide  103 . Referring to  FIGS. 37-39 , the leading end portion  106   e  of the tray  106  is tapered so that it is easier for the leading end portion  106   e  to be nipped by the combination of the conveyance roller  36  and pinch roller  37 . The leading end portion  106   e  is provided with a piece of thin plate, more specifically, a piece of Mylar, PET sheet, or the like, which is attached to the tip of the leading end portion  106   e . Next, referring to  FIG. 30 , the CD locking portion (center of CD accommodating recess)  106   e  of the tray  106  is provided with a pair of claws  106   f   1  and  106   f   2  which are separately located to keep a CD locked in the correct position. These claws  106   f   1  and  106   f   2  are integral parts of the tray  106 , and are resilient. They keep a CD locked in the correct position by being fitted into the center hole of the CD. 
   Designated by referential signs  106   b ,  106   c ,  106   m , and  106   n  are holes (CD removal holes) of the tray  106 , where fingers are hooked for removing a CD from the tray  106 . Designated by a referential sign  106   d  are grooves of the tray  106 , where fingers are placed to make it easier to handle the tray  106 . Further, the tray  106  is provided with a plurality of position detection marks (reflective marks)  106   g ,  106   h ,  106   i ,  106   j , and  106   k , among which the mark  106   k  has a hole  106   l . These marks enable the tray position detection sensor  71  on the recording head  7  to detect the precise position of the tray  106 , that is, the precise position of the CD in tray  106 . If an 8 cm CD (D 8 ) shown in  FIG. 44 , or a card-type CD (DC) shown in  FIG. 46 , instead of a CD of the normal size, that is, a 12 cm CD (D 12 ) shown in  FIG. 45 , is mounted in the CD placement recess of the tray  106   a , a step is created between the top edge of the peripheral surface of the 8 cm CD (D 8 ) or card-type CD (DC), and the bottom surface of the CD placement recess of the tray  106 , negatively affecting the efficiency with which the tray  106  is conveyed by the conveyance rollers or the like. Thus, when mounting these CDs of an odd size or shape, a tray adaptor (CD adaptor)  113  shown in  FIG. 31  is employed to prevent the problem. 
   The tray adaptor  113  is provided with an opening  113   z , the contour of which is virtually identical to the contour of the shape created by overlapping a disc, the diameter of which is the same as, or slightly greater than, that of the 8 cm CD (D 8 ), and a rectangle, which is identical in shape as that of a card-type CD, and the size of which is the same as, or slightly larger than, the card-type CD (DC). Further, the tray adaptor  113  has a plurality of positioning projections (attachment lobes)  113   b  and  113   c , which are fitted in the holes  106   b  and  106   c  of the tray  106  to accurately position the tray adaptor  113  relative to the tray  106 . Moreover, the tray adaptor  113  is provided with a rectangular hole (tray adaptor type detection hole)  113   a , which extends in the direction parallel to the tray conveyance direction so that after the mounting of the 8 cm CD (D 8 ) in the tray  106  with the use of the tray adaptor  113 , the tray adaptor type detection mark (reflective mark)  106   j  of the tray  106  is partially visible. 
   Further, in order to prevent the problem that the erroneous mounting of the tray adaptor by a user prevents the hole  113   a  from aligning with the mark  106   j  ( FIG. 30 ) of the tray  106  in the direction perpendicular to the tray  106 , the tray adaptor  113  is provided with a set of letters or a symbol designated by a referential symbol  113   d , the presence and direction of which are helpful to align the hole  113   a  with the mark  106   j  in the direction perpendicular to the tray  106 . In addition, the projections  113   b  and  113   c  are different in shape, preventing thereby the tray adaptor  113  from being mounted upside down. The holes  106   b  and  106   c  of the tray  106  are shaped so that the projections  113   b  and  113   c  of the tray adaptor  113  perfectly fit in the holes  106   b  and  106   c , respectively, to position the tray adaptor  113  relative to the tray  106 . When the projections  113   b  and  113   c  are the same in shape, they are desired to be nonsymmetrically positioned with respect to the center of the CD placement opening of the tray adaptor  113 . After the placement of the card-type CD (DC) in the tray  106  with the use of the tray adaptor  113 , the recording medium presence (absence) detection mark  106   l  of the tray  106  is partially visible. 
   Referring to  FIG. 38 , designated by referential numerals  107 A and  107 B are roller holders, by which the rollers  108 A and  108 B are rotatably supported, respectively, and which are located in the adjacencies of the left and right sides, respectively, of the tray  106  to evenly press down the tray  106 . The roller holders  107 A and  107 B have shafts  107 A a  and  107 B a , respectively, which are fitted in the bearings  102   e  of the sliding cover  102 , one for one, so that the roller holders  107 A and  107 B can be rotatable about the shafts  107 A a  and  107 B a , respectively. They are kept pressured downward by the springs  111  shown in FIG.  37 . Designated by a referential numeral  110  is a roller, which is rotatably attached to the tray guide  103  and is made to keep the tray  106  pressured by the force generated by an unshown spring. 
     FIGS. 37 and 40  are side views of the tray  106  and tray guide  103 , after the tray  106  which was holding a CD was inserted into the tray guide  103 , to a predetermined position, following the guiding surface of the tray guide  103 . In the drawings, the leading edge of the tray  106  is in contact with the discharge roller  41 A. The tray  106  is in the predetermined position, with its leading end being pressed upon the discharge roller  41 A by the rollers  108 A and  108 B which are under the pressure from the aforementioned springs  111 , while being kept pressured side way by the roller  110 . As the conveyance roller  36  is rotated in the counterclockwise direction (direction of arrow mark CCW in  FIG. 40 ) of the drawings while the recording apparatus is in the above described condition, the discharge roller  41 A is rotated also in the same direction, while conveying the tray  106 . After the leading edge  106   e  of the tray  106  is nipped by the conveyance roller  36  and pinch roller  37 , the tray  106  is conveyed further into the recording apparatus by the conveyance roller  36 , pinch roller  37 , and discharge roller  41 A. 
   More specifically, the tray  106  is conveyed a predetermined distance by the conveyance roller  36 , which is driven by an unshown LF motor (line feed motor, that is, conveyance motor).  FIG. 41  shows the recording medium in the tray  106 , ready to be recorded by the recording head  7 , and its adjacencies. As recording begins, the conveyance roller  36  and discharge roller  41 A are rotated in the clockwise direction in the drawing (direction of arrow mark CW), and the tray  106  is conveyed toward the front side of the recording apparatus by the conveyance roller  36 , pinch roller  37 , and discharge roller  41 A, while an image is recorded on the recording medium by the recording head  7 . In this embodiment, during the recording by the recording head  7 , the tray  106  remains sandwiched by the conveyance roller  36  and pinch roller  37 . Then, after the completion of the recording, the tray  106  is conveyed toward the front side of the recording apparatus (rightward in  FIG. 41 ) by the discharge roller  41 A, from when the leading edge  106   e  of the tray  106  loses contact with the conveyance roller  36  and pinch roller  37  until the leading edge  106   e  of the tray  106  loses contact with the discharge roller  41 A. 
   Referring to  FIG. 42 , designed by a referential numeral  106   g  is the portion of the right edge of the tray  106 , which is slightly recessed from the edge of the forward portion, in terms of the tray insertion direction. In the range corresponding to this recessed portion  106   g , the side roller  110  does not contact the tray  106 , and therefore, the tray  106  is not come under the pressure from the side roller  110 .  FIG. 42  shows the state of the tray  106 , CD therein, in the recording apparatus, at the end of the recording on a CD. At the beginning of recording (FIG.  33 ), the tray  106  is more inward of the recording apparatus main assembly than at the end of the recording (FIG.  42 ). In other words, from the beginning of recording to the end of recording, that is, while the tray  106  remains sandwiched by the conveyance roller  36  and pinch roller  37 , the tray  106  is not subjected to the pressure from the side pressure roller  110 . Incidentally, a portion  10   h  of the right edge of the tray  106 , on the outward side of which the edge is recessed (recessed edges  106   g ) is slanted to gradually reduce the pressure applied by the side pressure roller  110  as the tray  106  is inserted. After the completion of the recording on a CD, the tray  106  is removed from the tray guide  103 , and the sliding cover  102  is moved toward the front side of the recording apparatus. After the moving of the sliding cover  102 , the recording apparatus appears as shown in FIG.  32 . Then, the sliding cover  106  is to be moved further toward the front side. As the sliding cover  102  is moved further toward the front side, the projection  105   c  of the arm  105  shown in  FIG. 36  comes into contact with the projection  104   d  of the hook  104 , and rotates the hook  104  in the direction of an arrow mark a, causing the claw portion  104   b  to come out of the slot  99   b . As a result, the tray guide  103  is freed from the bottom case  99 , and the CD conveyance portion (CD unit)  101  comes out of the recording apparatus main assembly. 
   In this embodiment (ninth embodiment), the roller holders  107 A and  107 B, the shafts of which rotatably support the rollers  108 A and  108 B, on the left and right sides, respectively, are attached to the sliding cover  102 . However, they may be attached to the tray guide  103 . Also in this embodiment (ninth embodiment), the member for applying lateral pressure to the tray  106  is the roller  110 , that is, a rotational member. However, a plate spring may be substituted for the roller  110 . When recording is made on an ordinary recording medium, for example, a sheet of paper, using the recording apparatus in this embodiment, the following actions occur in the recording apparatus. That is, a sheet P sent from an unshown sheet feeding apparatus is conveyed to a predetermined position, and an image is formed on the sheet P by the recording head  7  while the recording head  7  is shuttled along a shaft  511  in the direction of the arrow mark A in the drawing, by an unshown motor, through a belt  552 . Then, the sheet P is conveyed a predetermined distance by the conveyance roller  36  and pinch roller  37 , and recording is made in the direction of the arrow mark A by the recording head  7 ; in other words, each time the sheet P is conveyed by the predetermined distance, recording is made on the sheet P in the direction of the arrow mark A. After the leading edge of the sheet P reaches the discharge roller  41 A, the above described recording action is repeated while the sheet P is held sandwiched not only by the conveyance roller  36  and pinch roller  37  but also by the pair of discharge rollers  41 . Eventually, recording is made across the entirety of the sheet P. The recording head  7  is provided with the tray position detection sensor (on-head sensor)  71 , which is capable of detecting, at a high degree of accuracy, the reflection type mark (position detection marks  106   g ,  106   h ,  106   i  . . . ) on the tray  106 , based on the received amount of the reflected light. 
   Next, referring to  FIGS. 43-48 , an operation for recording on a CD with the use of the CD conveyance portion  101  will be described.  FIG. 43  is a schematic top plan view of the tray  106  used with the recording apparatus, in the ninth embodiment of the present invention, showing the direction in which the tray  106  is conveyed, and the direction in which the recording head  7  and tray position sensor (on-head sensor)  71  are moved.  FIG. 44  is a schematic top plan view of the tray  106  shown in  FIG. 43 , which is used with the recording apparatus, in the ninth embodiment of the present invention, and which is holding the tray adaptor  113  and an 8 cm CD (D 8 ) in the opening of the tray adaptor  113 .  FIG. 45  is a schematic top plan view of the tray  106  in the ninth embodiment of the present invention, which is holding a 12 cm CD (D 12 ).  FIG. 46  is a schematic top plan view of the tray  106  shown in  FIG. 43 , which is used with the recording apparatus, in the ninth embodiment of the present invention, and which is holding the tray adaptor  113  and a card-type cm CD (DC) in the opening of the tray adaptor  113 .  FIG. 47  is schematic top plan view of the tray  106  shown in  FIG. 43 , which is holding the tray adaptor  113 , with no CD in the tray adaptor.  FIG. 48  is a schematic top plan view of the tray  106  which is used with the recording apparatus, in the ninth embodiment of the present invention, and which is too deep in the recording apparatus main assembly due to user error. 
   After a user sets the tray  106  in the tray guide  103 , the tray  106  is conveyed in the direction of the arrow mark Y to the recording starting position, while remaining sandwiched by the conveyance roller  36  and pinch roller  37 . While the tray  106  is conveyed, the tray position sensor  71 , as a tray position detection means, is kept at a point in the moving range of the recording head  7  (sensor  71 ), in terms of the direction of an arrow mark X in the drawing, at which the tray position sensor  71  is presumed to align with the position detection mark  106   h  of the tray  106  in terms of the direction of arrow mark Y. The tray  106  is slightly moved in the direction of an arrow mark +Y or −Y to detect the accurate position of the position detection mark  106   h  in terms of the Y direction, and the detected accurate position of the detection mark  106   h  is stored in a host or the like. After the detection of the accurate position of the detection mark  106   h , the recording head  7  is temporarily stopped, with the tray position sensor  71  accurately aligned with the position detection mark  106   h  in terms of the direction perpendicular to the tray  106 . Then, the recording head  7  is moved a predetermined distance in the +X direction shown in  FIG. 43 , and then, in the −X direction, to detect the accurate position of the position detection mark  106   h  in terms of the X direction by the position detection sensor (on-head sensor)  71 . Based on the accurate position of the position detection mark  106   h , the amount of the deviation of the tray  106  in the X direction can be calculated. Next, the recording head  7  is moved in −X direction to detect the position of the position detection mark  106   g  in terms of the X direction by the tray position detection sensor  71 . Then, the tray  106  is slightly moved in the +Y direction and −Y direction so that the accurate position of the position detection mark  106   g  in terms of the Y direction can be detected by the tray position detection sensor  71 . The detected accurate position of the position detection mark  106   g  is stored in the host or the like. 
   Based on the accurate positions of the position detection marks  106   h  and  106   g  stored in the host or the like, the degree of the slant of the tray  106  can be calculated. Then, recording is made while making compensation based on the obtained amount of the deviation in terms of the left or right direction and degree of the slant of the tray  106 , with reference to the recording data prepared in consideration of the deviation of the tray  106  in the left or right direction and the degree of slant of the tray  106 . Therefore, images with no positional deviation can be recorded. However, if a user pushes the tray  106  too far into the recording apparatus as shown in  FIG. 48 , it is impossible for the tray position detection sensor (on-head sensor)  71  to begin detecting the position detection mark  106   h , ending up detecting the mark  106   i  first. In such a case, the conveyance of the tray  106  is temporarily stopped, and the accurate position of the mark  106   i  is detected as if the mark  106   h  is detected as described above. In this case, however, the attempt to detect the position of the mark  106   g  by the tray position sensor  71  fails, proving that the detected position detection mark was the position detection mark  106   i . Then, the tray  106  is moved a predetermined distance in the −Y direction in  FIG. 43  by the conveyance roller  36  and pinch roller  37 , and the process of detecting the position of the mark  106   h  is started. 
   Next, based on the accurate positions of the position detection marks  106   h  and  106   g , the distance by which the tray  106  was moved is calculated. Then, the tray  106  and recording head  7  are moved until the tray position sensor  71  perfectly aligns with the mark  106   j  in terms of the direction perpendicular to the tray  106  to begin detecting the mark  106   j  in  FIG. 43  by the tray position sensor  71 . When the CD in the tray  106  is a 12 cm CD (D 12 ) as shown in  FIG. 45 , the mark  106   j  is hidden by the 12 cm CD (D 12 ). Therefore, the recording head  7  is moved further in the +X or −X direction to measure the fluctuation in the amount of the reflected light. If the fluctuation is relatively small, it is determined that the CD in the tray  106  is a 12 cm Cd (D 12 ). When using the tray adaptor  113  as shown in  FIG. 44 , or when neither the tray adaptor  113  nor recording medium (CD) is in the tray  106  as shown in  FIG. 30 , a part, or the entirety of the mark  106   j  can be detected through the hole (tray adaptor type detection hole)  113   a . More specifically, the tray position detection sensor  71  is moved in the +X and −X directions over the mark  106   j  to detect the fluctuation in the amount of the reflected light. If the amount of the reflected light detected by the sensor  71  when the sensor  71  is above the center portion of the mark  106   j  is substantially greater than that detected by the sensor  71  when the sensor  71  is away from the center portion of the mark  106   j  in the +X or −X direction, it is determined that either the tray adaptor  113  is present or no recording medium (CD) is present. 
   Next, the tray  106  is moved in the +Y direction, and is temporarily stopped directly above the top portion  106   ka  of the mark  106   k  shown in FIG.  30 . If an 8 cm CD (D 8 ) is in the tray  106  as shown in  FIG. 44 , the mark  106   ka  is hidden by the 8 cm CD (D 8 ). Next, the recording head  7  is moved in the +X and −X directions to detect the fluctuation in the amount of the reflected light. If the fluctuation in the amount of the reflected light is relatively small, it is determined that the recording medium in the tray  106  is an 8 cm CD (D 8 ). If a card-type CD (DC) is in the tray  106  as shown in  FIG. 46 , or no recording medium (CD) is in the tray  106  as shown in  FIG. 47  or  30 , the top portion  106   ka  can be detected. Then, the tray position detection sensor  71  is moved in the +X and −X directions while being kept over the mark  106   ka . If the amount of the reflected light detected by the sensor  71  when the sensor  71  is above the center portion of the mark  106   ka  is substantially greater than that detected by the sensor  71  when the sensor  71  is away from the center portion of the mark  106   ka  in the +X or −X direction, it is determined that either a card-type CD (DC) is in the tray  106  or no recording medium (CD) is present. 
   Next, the tray  106  is moved in the +Y direction, and is temporarily stopped directly above the top portion 106 kb of the mark  106   k  shown in FIG.  30 . If an 8 cm CD (D 8 ) is in the tray  106  as shown in  FIG. 44 , the top portion 106 kb of the mark  106   k  is hidden by the 8 cm CD (D 8 ). Next, the recording head  7  is moved in the +X and −X directions to detect the fluctuation in the amount of the reflected light. If the fluctuation in the amount of the reflected light is relatively small, it is determined that the recording medium in the tray  106  is a card-type CD (DC). As for the presence or absence of the tray adaptor  113  in the tray  106 , the tray position detection sensor  71  is moved in the +X and −X directions while being kept over the mark  106   j . If the amount of the reflected light detected by the sensor  71  when the sensor  71  is above the center portion of the mark  106   j  is substantially greater than that detected by the sensor  71  when the sensor  71  is away from the center portion of the mark  106   j  in the +X or −X direction, it is determined that the tray adaptor  113  is present. Incidentally, the above described position detection and control can be accurately carried out even when the photosensor used as the tray position detection sensor (on-head sensor)  71  is an inexpensive one. However, the employment of an expensive sensor, that is, a sensor of higher sensitivity, makes it possible to eliminate the hole  1061  of the mark  106   k  of the tray  106 . Further, the employment of a sensor of higher sensitivity makes it possible to eliminate the need for moving the tray position sensor  71  in the X direction to scan the fluctuation in the amount of the reflected light, temporarily stopping the tray  106  while moving the tray  106  in the Y direction, and the like operations. 
   It is possible through the above described procedures to determine which recording medium is in the tray  106 , a 12 cm CD (D 12 ) or a card-type CD (DC), whether or not a recording medium is in the tray  106 , and the like. Also through the above described procedures, it is possible to carry out a recording operation (printing method) in accordance with the determinations, or to issue a warning when no recording medium is in the tray  106 . When no recording medium is in the tray  106 , it is an operational error. Therefore, a user is instructed by some method (for example, a warning message is displayed by the host) to mount a recording medium. 
   (Embodiment 10) 
     FIG. 49  is a schematic top plan view of the tray adaptor (CD adaptor)  113  used with the recording apparatus, in the tenth embodiment of the present invention, and  FIG. 51  is a schematic bottom plan view of the tray adaptor shown in FIG.  49 .  FIG. 52  is a schematic top plan view of the tray  106  compatible with the tray adaptor  113  shown in  FIGS. 49 and 50 . Also in this tenth embodiment, the tray adaptor (CD adaptor)  113  is compatible with both an 8 cm CD (D 8 ) and a card-type CD (DC), as in the ninth embodiment, except that in this tenth embodiment, one surface (top side) is structured for an 8 cm CD (D 8 ) as shown in  FIG. 49 , and the other surface (bottom side) is structured for a card-type CD (DC) as shown in FIG.  50 . 
   Referring to  FIG. 49 , the top side of the tray adaptor  113  is provided with a recess  113   c , the diameter of which is the same as, or greater than, that of an 8 cm Cd (D 8 ), and the depth of which is equivalent to the thickness of a CD (roughly 1.2 mm). Referring to  FIG. 52 , the tray adaptor  113  is provided with a tray adaptor type detection hole (recording medium type detection hole)  113   a , which is located so that when the tray adaptor  113  is in the tray  106 , the tray adaptor type detection mark (recording medium type detection mark)  106   j , shown in  FIG. 52 , of the tray  106  can be partially detected. Also, the tray adaptor  113  is provided with an opening (hole)  113   z  which is located at the center of the recess  113   c  in order to accommodate the CD locking portion (CD positioning portion)  106   a  located at the center of the tray  106 . Further, in order to prevent a user from erroneously mounting a recording medium in such a manner that the tray adaptor detection hole (recording medium type detection hole)  113   a  does not overlap with the tray adaptor type detection mark (recording medium type detection mark)  106   j  shown in  FIG. 52 , the tray adaptor  113  is also provided with a set of letters or a symbol designated by a referential numeral  113   g , as is the tray adaptor  113  in the ninth embodiment. With the presence of the set of letters  113   g  or the symbol  113   g , the user can easily set a recording medium with reference to the direction of the set of letters  113   g  or symbol  113   g  so that the hole  113   a  is positioned directly above the mark  106   j.    
   Referring to  FIG. 50 , the bottom side of the tray adaptor  113  is provided with a rectangular recess  113   d , which is identical in shape, and is the same in size as, or slightly larger than, a card-type CD (DC), and the depth of which is equivalent to the thickness of a CD (roughly 1.2 mm). Further, the tray adaptor  113  is provided with projections  113   e  and  113   f  for accurately positioning the tray adaptor relative to the tray  106 . These projections  113   e  and  113   f  are symmetrically positioned with respect to the center of the tray adaptor  113 . Therefore, when mounting the tray adaptor  113  to use its bottom side, the tray adaptor  113  is to be mounted so that the B side ( FIG. 50 ) of the tray adaptor  113  comes to the top in FIG.  50 . In other words, the tray adaptor  113  is to be positioned so that the projections  113   e  and  113   f  of the tray adaptor  113  fit into the CD removal holes  106   b  and  106   c , respectively, of the tray  106 . Further, the tray adaptor  113  is provided with a tray adaptor type detection hole (recording medium type detection hole)  113   b , which is located so that when the tray adaptor  113  is in the tray  106  to use the bottom side of the tray adaptor  113 , the tray adaptor type detection mark (recording medium type detection mark)  106   j , as the means to be detected for position detection, shown in  FIG. 52 , of the tray  106  can be partially detected, as when the top side is used. Further, in order to prevent a user from erroneously mounting a recording medium in such a manner that the tray adaptor detection hole (recording medium type detection hole)  113   b  does not overlap with the tray adaptor type detection mark (recording medium type detection mark)  106   j  shown in  FIG. 52 , the tray adaptor  113  is also provided with a set of letters or a symbol designated by a referential numeral  113   h . With the presence of the set of letters  113   h  or the symbol  113   h , the user can easily set a recording medium with reference to the direction of the set of letters  113   h  or symbol  113   h  so that the hole  113   b  is positioned directly above the mark  106   j.    
   As will be evident from the above description, whether a recording medium is in the tray or not, and the type of the recording medium in the tray, can be determined by carrying out the operations similar to those in the ninth embodiment, with reference to the tray adaptor type detection hole (recording medium type detection hole)  113   b . In other words, the marks  106   k , hole  106   l , etc., which the tray in the ninth embodiment has, can be eliminated. Therefore, it is possible to reduce cost, and also, reduce the time necessary for recording medium identification. Further, unlike the trays in the preceding embodiments, the placement of a card-type CD in the tray  106  (bottom side of the tray  106 ) leaves virtually no recess (portion with step), improving thereby the CD conveyance performance. 
   (Embodiment 11) 
   In the tenth embodiment described above, the tray adaptor was structured so that an 8 cm CD (D 8 ) was mounted on one side (top side) of the tray adaptor, and a card-type CD (DC) was mounted on the other side (bottom side) of the tray adaptor, and the recording medium type was identified accordingly. Instead, the tray adaptor may be provided with a set of letters, a symbol, or the like, which shows the orientation of the tray adaptor relative to the tray, in relation to the type of a recording medium, so that the orientation of the tray adaptor can be changed in accordance with the recording medium to be used, as well as the marks, the shape of which can be detected by the tray position sensor  71  as a tray position detecting means to determine whether or not a recording medium is in the tray, or to identify the type of the recording medium (CD) in the tray; this is the method employed by the recording apparatus in the eleventh embodiment to identify the type of the recording medium in the tray. More specifically, the tray adaptor  113  is mounted in the tray in the orientation indicated by the set of letters, the symbol, or the like on the tray adaptor  113 , and the recording medium identification mark is identified, based on its shape, by the tray position detection sensor (on-head sensor)  71  to determine which recording medium is in the tray, an 8 cm CD (D 8 ) or a card-type CD (DC). 
   (Embodiment 12) 
     FIG. 53  is a schematic top plan view of an example of a tray adaptor used with the CD conveyance tray for the recording apparatus, in the twelfth embodiment of the present invention, and  FIG. 54  is a schematic top plan view of another example of a tray adaptor used with the CD conveyance tray for the recording apparatus, in the twelfth embodiment of the present invention. In recent years, there have been increased number of the CD shapes. Therefore, a tray adaptor (CD adaptor) must be prepared for each of the different CD shapes. Consequently, it has become imperative to be able to identify CDs different in shape in order to prevent recording errors or to make improvement in recording medium conveyance. Some of the answers to this need are to prepare a tray adaptor for each type of a CD, and
         to provide each tray adaptor with the tray adaptor type detection hole  113   a , as shown in  FIG. 53  or  54 , the difference in shape of which is detectable, and which is located so that it corresponds in position to the tray adaptor type detection mark (recording medium type detection mark)  106   j , as the means to be detected for tray adaptor type identification, the recording medium presence (absence) detection mark  106   k , shown in  FIG. 30 , in the ninth embodiment, and the tray adaptor type detection mark (recording medium type detection mark)  106   j  (FIG.  52 ), shown in  FIGS. 49 and 50 , in the tenth embodiment, so that recording can be made according to the shape of a CD; and   to provide each tray adaptor with a pair of tray adaptor type detection holes  113   a  and  113   b , as shown in  FIG. 55 , the difference in shape of which is detectable, and which are different in location, so that recording can be made according to the shape of a CD. Described above is the recording medium (CD) identification means of the recording apparatus, in the twelfth embodiment of the present invention.       
   The ninth-eleventh embodiments of the present invention were described with reference to the tray adaptor usable with recording media of two different types. However, a tray adaptor may be provided with a two tray adaptor type detection holes which correspond in position to the marks on the tray  106 , one for one, and which are different in shape. Such a structural arrangement also makes it possible to identify a recording medium just as effectively as the structural arrangement in the ninth-eleventh embodiments. Further, the ninth-eleventh embodiments may be employed in combination to realize a structural arrangement for identifying various recording media. 
   Further, the preceding embodiments of the present invention were described with reference to an ink jet recording apparatus as a recording apparatus. However, the present invention is also applicable to a recording apparatus which employs a recording method other than an ink jet recording method, for example, a wire-dot recording method, a thermal recording method, a laser beam recording method, or the like, and such an application will accomplish the same operational effects as those accomplished by the preceding embodiments. Further, not only is the present invention is applicable to a monochromatic recording apparatus, but also a color recording apparatus which records in various colors with the use of a single or plurality of recording heads, a tone recording apparatus which records in multiple densities of the same color with the use of a single ink, and a recording apparatus which operates in the combination of the operational modes of the preceding recording apparatuses, and such an application will accomplish the same effects as those accomplished by the preceding embodiments. 
   Further, the preceding embodiments were described with reference to a serial type recording apparatus, which records by moving the recording head as a recording means in the primary scanning direction. However, the present invention is also applicable to a line type recording apparatus, which has a line-type recording head long enough to reach from one edge of a recording medium to the other in terms of the width direction of the recording medium, and which records by moving the recording head only in the secondary scanning direction, and such an application will accomplish the same effects as those accomplished by the preceding embodiments. 
   Further, the present invention is also applicable to such an ink jet recording apparatus, that is, as an ink jet recording apparatus which records with the use of liquid ink, and which is structured to employ a replaceable head cartridge integrally comprising a recording head and an ink container, as well as an ink jet recording apparatus structured so that the recording head is connected to a separate ink container with the use of an ink supply tube or the like. In other words, the present invention is applicable regardless of recording head structure, ink container structure, and the arrangement between the recording head and ink container. Such an application will bring forth the same effects as those brought by the preceding embodiments. 
   Further, the present invention is also applicable to an ink jet recording apparatus employing an electromechanical transducer such as a piezoelectric element. However, when it is applied to an ink jet recording apparatus employing a recording means which uses thermal energy to eject ink, it brings forth superior effects, because such a recording means can accomplish a higher level of recording density and can record at a higher level of precision. 
   While the invention has been described with reference to the structures disclosed herein, it is not confined to the details set forth, and this application is intended to cover such modifications or changes as may come within the purposes of the improvements or the scope of the following claims.