Abstract:
A reliable detection of optically detecting the type of recording media is achieved. A part of a support member for supporting an optical sensor is pushed against the surface of a sheet by a spring so as to maintain the gap between the sensor and the sheet surface. With this arrangement, a recording apparatus which is free from wrong detection is achieved regardless of a gap-varying factor, that is, the remaining amount of sheets. Also, by arranging a part of a light-shielding hood so as to abut against the sheet, wrong detection due to disturbance light can be prevented.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a recording apparatus which detects the type of recording media. 
   2. Description of the Related Art 
   Hitherto, recording apparatuses such as a printer and a printing machine which perform recording with ink on a recording medium such as a recording sheet have been widely used. 
   In recent years, the types of recording media have become diversified as the requirements of the market have become more diversified and the recording apparatuses have become more advanced. A variety of recording media, such as a recording sheet whose image quality has been improved by providing an ink receiving layer on the surface thereof, a paperboard such as a postcard having a thickness of at least 0.3 mm, and a piece of cloth which can be recorded on by using a printer, have been commercially used. 
   Typical recording apparatuses usable for the variety of such recording media are inkjet printers. 
   In an inkjet printer, the bleeding degree or the coloring state of ink discharged on a recording medium varies depending on the type of the recording medium. Thus, in order to achieve the best image quality, an operator sets the discharge amount and the discharge times of ink from nozzles in accordance with the type of a recording medium by instructing the printer about the type of the recording medium being used from a host computer or from instructing means of the printer. 
   The increased number of these instructions due to the increased types of recording media causes a complicated operation for an operator, and the printer cannot warn the operator of the wrong instruction when the operator provides a wrong instruction, thereby sometimes resulting in a recorded output having low image quality. 
   Also, when a network printer is shared by a plurality of operators and is not installed near some of the operators, the operators are required to go to the printer for checking what type of recording media is stored in a recording medium storage (or storage unit) before instructing the type of recording media being used, thereby causing the printer to be used inefficiently. 
   In a printer in which a necessary type of a recording medium can be selected from among a plurality of types of recording media, for example, by having multi-stage cassettes installed therein, an operator can realize which type of recording media is stored in which cassette only when the operator actually pulls out the cassettes, thereby causing the printer to be used inefficiently. 
   Some devices for detecting the type of recording media have been provided in order to overcome such disadvantages. 
   U.S. Pat. No. 6,151,040 has disclosed a recording apparatus and a recording method in which and by which the type of recording media is detected and recording conditions of a recording head are changed in accordance with the detected type of recording media. 
   Also, Japanese Patent Laid-Open No. 10-198174 has disclosed a sheet-type detector in which the type of sheets is detected by irradiating the uppermost sheet with light emitted from a light-emitting device and by detecting the reflected light by a photo receptor in order to improve its detection accuracy by setting angles of the light-emitting device and the photo receptor in the range from 15° to 30° with respect to the sheet. 
   In addition, Japanese Patent Laid-Open No. 71-181756 has disclosed an image forming apparatus having a recording-sheet-type detecting function in which a color sensor is disposed for detecting the type of recording sheets in each of multi-stage cassettes and, when the sensor detects the type of recording sheets, the detected information is displayed on a display unit of the apparatus. In this apparatus, when an operator operates a sheet-type selection switch at an operation unit of the apparatus so as to designate the type of recording sheets in advance to be used for making a copy of desired pages of originals consisting of a plurality of sheets, the copy is automatically made using the desired type of sheets. 
   However, the foregoing known examples have the following disadvantages. 
   In the recording apparatus disclosed in U.S. Pat. No. 6,151,040, after a starting command for printing is issued, the type of recording media is detected by recording-medium-type detecting means disposed at a point halfway through the transport route of the recording medium toward a recording section of the recording apparatus and the recording medium is subjected to recording under recording conditions in accordance with the type thereof. However, in this recording apparatus, since a printer driver in a host computer starts in reality to create printing data under certain recording conditions as soon as the starting command for printing is issued, and the data is transferred to the recording apparatus, it is difficult to change the recording conditions halfway through the transport of the recording medium. 
   When the recording apparatus is designed not to create recording data in a period from the issue of a starting command for printing to the completion of detecting the type of recording media, although there is no need to change the recording conditions halfway through the transport of the recording medium, the recording apparatus has a disadvantage of a prolonged recording time in total. 
   According to the invention set forth in Japanese Patent Laid-Open No. 10-198174, since the light-emitting device and the photo receptor are disposed in each cassette, the recording data can be created after the type of recording media in the cassette is detected in advance. However, this invention has a disadvantage that when distances of the light-emitting device and the photo receptor from the surface of the uppermost sheet change as the amount of remaining sheets varies, the amount of received light of the photo receptor varies, thereby leading to an unreliable determination about an output and resulting in wrong detection. 
   The invention set forth in Japanese Patent Laid-Open No. 7-181756 also has a disadvantage that since the color sensor for detecting the type of recording sheets is fixed at a specific location in the cassette, a change in a distance of the color sensor from the surface of the uppermost sheet causes wrong detection. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a recording apparatus which maintains the distance between a medium detection sensor and the uppermost recording medium constant regardless of the remaining amount of recording media in a recording-medium storage so as to reliably detect the type of recording media. 
   It is another object of the present invention to provide a recording apparatus for recording data on a recording medium, which comprises a recording medium storage for storing a plurality of sheets of recording media; at least one feeding roller for feeding the recording media sheet by sheet from said recording medium storage; a medium detection sensor for detecting the type of the recording media; and a gap maintaining member for maintaining the gap between said medium detection sensor and the recording medium fed by said feeding roller. 
   Further objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments with reference to the attached drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a general perspective view of a recording apparatus according to a first embodiment of the present invention. 
       FIG. 2  is a perspective view of an automatic sheet feeder (ASF) of the recording apparatus according to the first embodiment. 
       FIG. 3  is a side view of the ASF viewed from the arrow A indicated in FIG.  2 . 
       FIG. 4  is a sectional view of the ASF taken along the line B—B indicated in FIG.  2 . 
       FIG. 5  illustrates a sensor and the vicinity thereof of the recording apparatus according to the first embodiment. 
       FIGS. 6A  to  6 D illustrate a cam operational diagram of the recording apparatus according to the first embodiment. 
       FIG. 7  is a flowchart illustrating an operation of the recording apparatus according to the first embodiment. 
       FIG. 8  is a side view of an ASF of a recording apparatus according to a second embodiment of the present invention. 
       FIGS. 9A and 9B  are side views of a cassette of a recording apparatus according to a third embodiment of the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Specific embodiments of the present invention will be described with reference to the accompanying drawings. 
   First Embodiment 
     FIG. 1  is a general perspective view of a recording apparatus according to a first embodiment of the present invention. 
   As shown in  FIG. 1 , the recording apparatus has a chassis  1 , which has a structure for supporting other components, and an automatic sheet feeder (hereinafter, abbreviated to ASF) base  2 , which will be described later. 
   A sheet fed by the ASF is forwarded to the nips between a line feed (hereinafter, abbreviated to LF) roller  6  and pinch rollers  7 . The surface of the LF roller  6  is coated so as to have a predetermined coefficient of friction. Both ends of each pinch roller  7  composed of rubber are rotatably supported by a corresponding pinch roller guide  8  such that the pinch roller  7  rotates freely. The pinch roller guides  8  are rotatable about corresponding rotating shafts  9  and the pinch rollers  7  are urged against the LF roller  6  by corresponding not-shown springs. When the leading edge of the sheet picked up by feeding rollers, which will be described later, reaches the LF roller  6  lying at a standstill, the sheet is forwarded by the feeding rollers by several millimeters further. The sheet is deformed in a rolled shape in this process, and the leading edge of the sheet is aligned by its own stiffness. When the alignment of the leading edge of the sheet is finished, the LF roller  6  starts to rotate so as to forward the sheet to a recording section while the sheet is being sandwiched by the LF roller  6  and the pinch rollers  7 . 
   The LF roller  6  has an LF gear  10  press-fitted into the left end thereof with the chassis  1  interposed therebetween. The LF gear  10  is integrally formed with an LF pulley  11  in a coaxial manner. The LF pulley  11  has an LF belt  12  looped thereover so as to drive a sheet-discharging pulley  13  disposed downstream. The LF gear  10  forms a gear train together with an LF motor gear  14  and is driven by an LF motor  15 . 
   The sheet sandwiched between the LF roller  6  and the pinch rollers  7  is transported over the surface of a platen  16 . A sheet-discharging roller  17  is fixed to the sheet-discharging pulley  13  and driven by the LF motor  15 . The sheet-discharging roller  17  has 11 rubber components  18  attached thereon, each having not-shown urging means so as to urge a corresponding spur  19 . The platen  16  has 11 ribs  101  disposed on the surface thereof. 
   An inkjet recording head  20  performs recording by discharging ink and has four ink tanks  24  to  27  therein corresponding to black, cyan, magenta, and yellow colors. The ink tank for the black color has a larger capacity than the other ink tanks, taking its frequency of use into account. 
   The inkjet recording head  20  has 4 nozzle rows for each color, each nozzle row disposed with a pitch of 1/600 inches in the sheet forwarding direction and having 300 nozzles. 
   The inkjet recording head  20  is inserted, positioned, and fixed in a carriage  29 . The carriage  29  has electrode units  30  for respective black and color recording, disposed therein in order to transmit signals from the main body of the recording apparatus to the inkjet recording head  20 . When the inkjet recording head  20  is set in the carriage  29 , each of the electrode units  30  is pushed to a not-shown head electrode disposed on the inkjet recording head  20  and becomes in a conducting state. Some of these electrodes serve as electrodes for determining whether the head is set or not. That is, it is possible to determine whether the head  20  is mounted or not by measuring a resistance between two of the determining electrodes. The head  20  is positioned by datum planes  45  and  46 . 
   By using a flexible cable  31 , the carriage  29  is coupled with a main board  32  fixed on the rear surface of the chassis  1 . The flexible cable  31  has the foregoing electrode units  30  disposed at one terminal thereof. 
   A carriage shaft  33  extends through a bearing  34  of the carriage  29 . Both ends of the carriage shaft  33  are supported by the chassis  1 . A not-shown slider disposed downstream from the carriage  29  slides on a carriage rail  35 , and both ends of the carriage rail  35  are also supported by the chassis  1 . 
   The carriage  29  having the inkjet recording head  20  mounted thereon is guided by the carriage shaft  33  and the carriage rail  35  so as to move in a direction perpendicular to the sheet forwarding direction. The carriage  29  has a carriage belt  36  bonded thereto, which is looped over a pulley of a carriage motor  37  and an idler pulley  38 . The carriage  29  moves in a reciprocating manner while being driven by the carriage motor  37  via the carriage belt  36 . While the carriage  29  is moving, the orifice surfaces of the nozzles of the inkjet recording head  20  and the sheet surface are maintained so as to have a gap of 1.5 mm therebetween. 
     FIG. 2  is a perspective view of the ASF having a recording-medium-type detector which is the main feature of the present invention,  FIG. 3  is a side view of the ASF viewed from the arrow A indicated in  FIG. 2 , and  FIG. 4  is a sectional view of the ASF taken along the line B—B indicated in FIG.  2 . 
   As shown in  FIG. 2 , the ASF base  2  and two right and left feeding rollers  51  are provided. A sheet having a size of A 4  or the like is fed using these two feeding rollers  51 . When a sheet having a small size such as a postcard is fed, the right feeding roller  51  and an auxiliary feeding roller  52  are used. The surfaces of these rollers are composed of rubber so as to provide a large frictional force against a sheet. The feeding rollers  51  and the auxiliary feeding roller  52  are fixed to a feeding roller shaft  53 . Each of the auxiliary feeding roller  52  and the feeding roller shaft  53  has collars  80 , integrally formed with the feeding roller shaft  53 , at both ends of its rubber part. As shown in  FIG. 4 , when a pressure plate  59 , which will be described later, ascends towards the feeding rollers  51 , the uppermost sheet loaded on the pressure plate  59  first comes into contact with the collars  80 . Subsequently, the feeding roller shaft  53  rotates by a predetermined amount, and then the sheet loaded on the pressure plate  59  comes into contact with the rubber parts of the feeding rollers  51  and starts to be forwarded. With this arrangement, the sheet loaded on the pressure plate  59  is prevented from being forwarded in a state in which a contact pressure between the sheet and the feeding rollers  51  is unstable due to vibrations occurring right after the ascending of the pressure plate  59 , thereby preventing a problem that the sheet is forwarded at a slanted angle. Both ends of the feeding roller shaft  53  are rotatably supported by the ASF base  2  so that the feeding roller shaft  53  is rotatable together with the feeding rollers  51 . The feeding roller shaft  53  has a feeding cam gear  54  fixed at the right end thereof. The feeding cam gear  54  engages with an input gear  55  having two idler gears  56  interposed therebetween. The input gear  55  is driven by a not-shown drive source. Upon moving in the direction indicated by the arrow C shown in  FIG. 3 , a cam  57  of the feeding cam gear  54  abuts against a cam follower  60  integrally formed with the pressure plate  59 , thereby causing the pressure plate  59  to be pressed into contact with or detached from the feeding rollers  51 . The pressure plate  59  can turn about right and left pressure-plate shafts  61  as shown in FIG.  4 . The ASF base  2  and the pressure plate  59  have pressure-plate springs  63  inserted between the rear surfaces thereof so as to urge the pressure plate  59  against the feeding rollers  51 . In a state shown in  FIG. 4 , since the pressure plate  59  is kept away from the feeding rollers  51 , the pressure-plate springs  63  are fully compressed. When sheets  3  are loaded on the pressure plate  59  as shown in  FIG. 1 , the uppermost sheet is urged against the feeding rollers  51  and is brought forward as the feeding rollers  51  rotates. 
   In a state shown in  FIG. 3 , a separation claw  64  is stretched by a claw spring  65 . When the leading edges of the sheets  3  reach the separation claw  64 , and if the sheets  3  are thin, the sheets  3  are deformed into a rolled shape by the separation claw  64 , and only the uppermost sheet  3  is separated from the remaining sheets  3  by the so-called claw separation of the separation claw  64  and is fed. If the sheets  3  are so thick that they are not deformed into a rolled shape, the sheets  3  having large stiffness cause the separation claw  64  to fall down against an urging force of the claw spring  65 , and only the uppermost sheet  3  is separated from the remaining sheets  3  by the bank separation of a bank  66  shown in FIG.  4  and is fed. A movable bank  67  is disposed upstream from the bank  66  and has an upward angle so as to prevent the loaded sheets  3  from falling down. When the sheet  3  is fed, in conjunction with the rotation of the feeding rollers  51 , not-shown cam means causes the movable bank  67  to move in the direction indicated by the arrow E shown in  FIG. 4  such that the sheet  3  is easily fed. Upon completion of feeding the sheet  3 , the movable bank  67  returns to its original position. 
   A side guide  5  is slidable in accordance with the width of sheets, and an auxiliary feeding tray  69  is retractable in accordance with the length of the sheets. 
   A medium-detection-sensor control cam  70  shown in  FIGS. 2 and 3  engages with the feeding cam gear  54  and rotates in the direction indicated by the arrow D shown in  FIG. 3  in synchronization with the feeding cam gear  54 . A sensor support  72  has two pins  73  integrally formed therewith. The pins  73  are inserted into corresponding slots  74  formed on the side surface of the ASF base  2 . The sensor support  72  is supported by the ASF base  2  by using a not-shown latch so as to be slidable along the longitudinal direction of the slots  74 . The cam surface of the medium-detection-sensor control cam  70  lies in contact with the right pin  73 . Also, the right pin  73  is pushed to the cam surface of the medium-detection-sensor control cam  70  by a sensor spring  75  disposed between the right pin  73  and a spring retainer  76  disposed on the ASF base  2 . With this structure, the sensor support  72  moves linearly as the medium-detection-sensor control cam  70  rotates. 
   Referring now to  FIG. 5 , a medium detection sensor will be described. The medium detection sensor is disposed at the top of the sensor support  72 . As shown in  FIG. 5 , a light emitting device  77  for emitting light at 45 degrees with respect to the sheet surface and a photo receptor  78  for detecting part of the light reflected at the sheet surface are fixed to the sensor support  72 . Since the amount of reflected light depends on the surface property of a sheet, the type of the sheet can be specified on the basis of the amount of reflected light. A hood  79  is disposed in order to maintain the distance between the light emitting device  77  and the photo receptor  78  and the surface of the sheet  3  constant and also to cut off outside light. The hood  79  has an approximately conical shape so as to surround the top of the sensor support  72  and moves together with the sensor support  72 . The hood  79  has a hood rubber  81  disposed along the periphery of the opening thereof such that the hood  79  and the sheet  3  lie in close contact with each other even when the hood  79  and the sheet surface have a slight angle with each other. Since the opening of the hood  79  abuts against the sheet surface while being pushed by a load of the foregoing sensor spring  75 , the distance between the light emitting device  77  and the photo receptor  78  and the surface of the sheet  3  is always maintained constant while the type of recording sheets is being detected. 
   A recording operation will be described with reference to  FIGS. 6A  to  6 D illustrating an operational diagram of the cams and  FIG. 7  illustrating a flowchart of an operation of the recording apparatus. For simplification, only a part of the recording apparatus lying in the vicinity of the cams is illustrated in  FIGS. 6A  to  6 D and the other part which is unnecessary for this description is omitted. 
   In a state shown in  FIG. 6A , when the power is to be turned on (STEP  1 ), the pressure plate  59  is detached from the feeding roller  51  by the cam  57  and the sheet  3  is kept away from the opening of the hood  79 . Also, the pins  73  are at rest while abutting against the cam surface of the medium-detection-sensor control cam  70 . Accordingly, sheets can be easily loaded in this state. 
   Then, in a state shown in  FIG. 6B , when a recording signal is input (STEP  2 ), the feeding cam gear  54  and the medium-detection-sensor control cam  70  rotate by 45 degrees. Since the cam  57  moves and the pressure plate  59  moves upwards, the foregoing collars  80  come to rest upon coming into contact with the sheets loaded on the pressure plate  59 . At the same time, the sensor support  72  is pushed up by the surface of the uppermost sheet  3  and the right pin  73  is detached from the cam surface of the medium-detection-sensor control cam  70  by a distance of 1 mm. In this state, the type of recording media is detected (STEP  3 ). On the basis of the detected information, a driver attached to a host computer sets the optimal discharge amount and the discharge times of ink from the nozzles in accordance with the type of recording media (STEP  4 ). 
   In a state shown in  FIG. 6C , when the feeding cam gear  54  and the medium-detection-sensor control cam  70  rotate 10 degrees further, the feeding roller  51  comes into contact with the pressure plate  59  so as to start feeding the sheet  3 . Shortly before feeding the sheet  3 , the cam surface of the medium-detection-sensor control cam  70  comes into contact with the right pin  73 , the sensor support  72  moves, and the hood rubber  81  is detached from the sheet  3  (STEP  5 ). As a result, the sheet  3  to be fed and the hood rubber  81  do not come into contact with each other. 
   In a state shown in  FIG. 6D , when the cam  57  and the cam follower  60  start to come into contact with each other and the pressure plate  59  starts to be detached from the feeding roller  51 , the sensor support  72  moves downwards along the cam surface of the medium-detection-sensor control cam  70  and the cam operation returns to the state shown in  FIG. 6A  (STEP  6 ). 
   The position of the sheet, fed as mentioned above, is detected in the transport direction thereof by a not-shown sensor and the sheet comes to rest at a predetermined recording start position (STEP  7 ). 
   Then, the carriage  29  scans the sheet  3  and performs recording of the data of one line (STEP  8 ). When data to be recorded still remains (STEP  9 ), the sheet  3  is forwarded by a space of 300 nozzles, and the carriage  29  performs recording of the data of the following line (STEP  10 ). Subsequently, the scanning of the carriage  29  and the forwarding of the sheet  3  are repeatedly performed until no data to be recorded remains, and when this recording operation is completed, the sheet  3  is discharged into a not-shown discharge tray (STEP  11 ). When the second page is to be recorded (STEP  12 ), the recording operation is returned to STEP  2  and the same operation is repeated; otherwise, the recording apparatus is put in a standby mode. 
   Means for maintaining the gap between the medium detection sensor and the sheet surface constant while the type of recording media is being detected is not limited to that according to this embodiment; all means including the one in which an additional drive source moves the medium detection sensor in accordance with a phase of the pressure plate are applicable as long as they maintain the above-mentioned gap constant. In this embodiment, when the sheets  3  are to be loaded, the sheets  3  become free from being urged by detaching the pressure plate from the sheets  3 , and, when the sheet  3  is to be fed, the sheet  3  becomes free from being urged by detaching the sensor support  72  from the sheet  3 . However the present invention is not limited to the above-mentioned structure; it may have a structure in which all urges are released by the sensor support  72 . In this case, the medium detection sensor may be disposed on the pressure plate. 
   The medium detection sensor is not limited to a combination of a light-emitting device and a photo receptor; a variety of other means including the one in which an image scanning device such as a CCD is used so as to specify the type of recording sheets by scanning an image pattern of the sheet surface are applicable to the present invention. 
   Second Embodiment 
     FIG. 8  is a side view of a recording apparatus according to a second embodiment of the present invention, wherein like components as in the first embodiment are omitted. 
   An ASF base  200  shown in  FIG. 8  has the same function as that in the first embodiment. A light-emitting device  201  and a photo receptor  202  detect the type of recording media based on the same principle as that in the first embodiment. The light-emitting device  201  and the photo receptor  202  are supported by a sensor-support slider  203 . A shaft of the sensor-support slider  203  is guided by a hole formed in a slider casing  204  so as to move in the direction indicated by the arrow F shown in FIG.  8 . The slider casing  204  is fixed to the side surface of the ASF base  200  with screws. The shaft of the sensor-support slider  203  is also inserted into a compression spring  205 . The light-emitting device  201  and the photo receptor  202  are surrounded by a hood  207  having rollers  208  disposed at two places on the side surfaces of the hood  207 . 
   In this embodiment, the sensor-support slider  203  is always urged towards the surface of the uppermost sheet  3  by the compression spring  205 . When the type of recording sheets is detected, the rollers  208  come into contact with the surface of the uppermost sheet. When the sheet is fed, since the rollers  208  rotate as the sheet moves, the rollers  208  do not cause a resistance for transporting the sheet. 
   According to this embodiment, the cam mechanism for moving the sensor support  72  is not needed, thereby achieving a simple structure of the recording apparatus. 
   Third Embodiment 
     FIGS. 9A and 9B  are side views of a cassette of a recording apparatus according to a third embodiment of the present invention, wherein  FIG. 9A  illustrates a state in which the cassette is loaded and  FIG. 9B  illustrates a state in which the cassette is unloaded. Recording media  301  are stored in a cassette  300  having therein a pressure-plate spring  302  and a pressure plate  304 , which is urged upwards about a fulcrum  303  as a rotating axis. As shown in  FIG. 9A , when the recording media  301  are fed, the surface of the uppermost recording medium  301  comes into contact with the surface of a feeding roller  305  by a not-shown cam. When the feeding roller  305  rotates clockwise in  FIG. 9A , the recording media  301  are forwarded and only the uppermost one is separated and picked up by a separation claw  306 . A light-emitting device and a photo receptor are disposed at the top of a sensor support  307  in the same fashion as in the first embodiment. Since a hood  308  has the same function as that in the first embodiment, its description is omitted. A shaft of the sensor support  307  is inserted into and guided by a hole of a sensor lever  309  so as to be vertically slidable. A compression spring  310  has the same function and structure as those in the second embodiment. The sensor lever  309  has a rotating shaft  311  protruding therefrom and a torsion coil spring  312  which is hooked on the rotating shaft  311  so as to urge the sensor lever  309  counterclockwise. In addition, the sensor lever  309  has a projection  313 . In a state in which the cassette  300  is loaded, the projection  313  abuts against an abutment  314  disposed on the exterior frame of the cassette  300  and keeps the cassette  300  horizontal against a load of the torsion coil spring  312 . In this state, rollers  315  rotatably supported by the hood  308  in the same fashion as in the second embodiment lie in contact with the uppermost recording medium  301  and compress the compression spring  310  so as to exert a contact load on the recording media  301 . 
   When the cassette  300  is unloaded as shown in  FIG. 9B , since the projection  313  is detached from the abutment  314 , the sensor lever  309  rotates counterclockwise with the load of the torsion coil spring  312  and abuts against a not-shown stopper to a halt. 
   The cassette  300  can be loaded again without a chance of the rollers  315  and the hood  308  coming into contact with the surface of the uppermost recording medium  301 , thereby allowing the cassette  300  to be easily loaded and preventing a surface flaw of the recording medium  301 . At the last moment of inserting the cassette  300 , the rollers  315  come into contact with the surface of the uppermost recording medium  301  and the type of the recording media  301  stored in the cassette  300  is ready to be detected at any given timing. 
   That is, the detection may be performed whenever the cassette  300  is loaded or only when instructed by instructing means disposed independently. 
   As described above, according to this embodiment, since there are provided a recording medium storage for storing a plurality of sheets of recording media, feeding rollers for feeding the recording media sheet by sheet from the recording medium storage, a medium detection sensor, and a gap maintaining member for maintaining the gap between the medium detection sensor and the recording medium fed by the feeding rollers, the gap between the medium detection sensor and the recording medium fed by the feeding rollers can be maintained constant regardless of the remaining amount of the recording media stored in the recording medium storage, thereby achieving a recording apparatus which can reliably detect the type of recording media. 
   While the present invention has been described with reference to what are presently considered to be the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.