Patent Publication Number: US-2022236684-A1

Title: Conveyance apparatus and printing apparatus

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present disclosure relates to a conveyance apparatus that conveys a printing medium and in detail, relates to a detection unit configured to detect the presence/absence of a printing medium in a conveyance path within the apparatus. 
     Description of the Related Art 
     Conventionally, in a conveyance apparatus that conveys a printing medium in the form of sheet, A detection unit configured to detect a printing medium in a conveyance path of the printing medium is provided and predetermined processing is performed for the detected printing medium after detecting the presence/absence of the printing medium. As the detection unit such as this, a detection lever that detects the abutment of a printing medium is known. 
     Japanese Patent Laid-Open No. 2011-201615 has disclosed a guide of a printing medium, which is capable of opening the conveyance path by rotation, and a detection lever. In Japanese Patent Laid-Open No. 2011-201615, due to the position relationship between the guide and the rotation axis of the detection lever, in a case where the guide is opened at the time of paper jam processing, the detection lever retracts into the inside of the guide. 
     SUMMARY OF THE INVENTION 
     However, in Japanese Patent Laid-Open No. 2011-201615, the detection lever and a light-shielding lever move integrally irrespective of the position of the guide. Consequently, there is a possibility that an impact is exerted on the guide erroneously at the time of opening the guide for the purpose of solving a conveyance abnormality of a printing medium, and there is a risk that the detection unit is damaged in a case where the detection lever comes off and falls, and so on. 
     Consequently, an object of one embodiment of the present invention is to provide a conveyance apparatus whose detection unit of a printing medium is unlikely to be damaged. 
     One embodiment of the present invention is a conveyance apparatus including: a first guide that is fixed to a main body; a second guide capable of moving to a position at which the second guide forms, together with the first guide, a conveyance path through which a printing medium is conveyed and a position at which the second guide opens the conveyance path; a first lever that is provided to the main body and which detects whether or not the printing medium exists in the conveyance path; and a second lever that shields light, wherein the first lever and the second lever can swing integrally or independently in accordance with the position of the second guide. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a perspective diagram showing an outer appearance of a printing apparatus  1  in a closed state; 
         FIG. 1B  is a perspective diagram showing an outer appearance of the printing apparatus  1  in an open state; 
         FIG. 2A  is a perspective diagram showing an internal mechanism of the printing apparatus  1  in an open state; 
         FIG. 2B  is a cross-sectional diagram showing the internal mechanism of the printing apparatus  1  in an open state; 
         FIG. 3A  is a perspective diagram of an intermediate conveyance unit  90  and a sheet material detection unit  80 ; 
         FIG. 3B  is a perspective diagram of the sheet material detection unit  80 ; 
         FIG. 4A  is an explanatory diagram of a first position that the sheet material detection unit  80  can take; 
         FIG. 4B  is a perspective diagram of the sheet material detection unit  80  located at the first position; 
         FIG. 5A  is an explanatory diagram of a second position that the sheet material detection unit  80  can take; 
         FIG. 5B  is a perspective diagram of the sheet material detection unit  80  located at the second position; 
         FIG. 6A  is an explanatory diagram of a third position that the sheet material detection unit  80  can take; 
         FIG. 6B  is a perspective diagram of the sheet material detection unit  80  located at the third position; 
         FIG. 7  is a block diagram of a control unit; 
         FIG. 8  is a flowchart of initialization processing of a sub scanning system; 
         FIG. 9  is a flowchart of sheet feed preparation processing; and 
         FIG. 10  is a diagram explaining each state of the printing apparatus  1 . 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     First Embodiment 
     &lt;General Configuration of Printing Apparatus&gt; 
       FIG. 1A  is a perspective diagram showing an outer appearance of a printing apparatus  1  having a conveyance apparatus of a printing medium according to a first embodiment. The printing apparatus  1  has a substantially cuboid shape on the whole and a reading device  3  is provided on the top section of a main body  2  so that the reading device  3  can open and close freely and on the front face of the main body  2 , a touch-panel display device  4  that receives the operation of a user is provided. 
       FIG. 1B  is a perspective diagram showing a state (called open state) where each of the reading device  3  and an ink tank cover  5  rotates and opens. On the front face of the printing apparatus  1 , an ink filling port  6  for ink filling is provided. To explain coordinate axes in each of  FIG. 1A  and  FIG. 1B , an arrow X indicates the width direction of the printing apparatus  1 , an arrow Y indicates the depth direction of the printing apparatus  1 , an arrow Z indicates the vertical direction (height direction of the printing apparatus  1 ) and these directions are perpendicular to one another. For the sake of explanation, in the other diagrams as well, to be explained later, the same coordinate axes as those in  FIG. 1A  and  FIG. 1B  are set as needed. 
     The printing apparatus  1  is a serial ink jet printing apparatus that prints an image by ejecting ink supplied from an ink tank  7  onto a printing medium, but it is also possible to apply the present embodiment to another type of serial printing apparatus. “Printing” includes, in a broad sense, not only a case where significant information, such as a character and a figure, is formed but also a case where an image, a pattern or the like is formed on a printing medium whether or not they are significant, or a medium is modified, and printing is irrespective of whether or not it creates something so that it can be perceived by the human visual sense. Further, in the present embodiment, as the “printing medium”, paper in the form of sheet is supposed, but the “printing medium” may be cloth, plastic, film, or the like. 
       FIG. 2A  is a perspective diagram showing the internal mechanism of the printing apparatus  1  and  FIG. 2B  is a cross-sectional diagram showing the internal mechanism of the printing apparatus  1 . The printing apparatus  1  has a printing unit  10 , feeding units  20 A to  20 C, a conveyance unit  30 , and a discharging unit  40 . 
     The feeding unit  20 A, the feeding unit  20 B, the feeding unit  20 C, the conveyance unit  30 , and the discharging unit  40  are each a mechanism of conveying a printing medium. There is a case where the conveyance direction of a printing medium is called “sub scanning direction” and the source side of conveyance (loading table side) is called “upstream side” and the destination side of conveyance (discharge tray side of the discharging unit) is called “downstream side”. The sub scanning direction of the present embodiment includes the +Y-direction (feed direction) and the −Y-direction (return direction) in a planar view of the printing apparatus  1 . 
     The printing apparatus  1  has three feeding paths and specifically, the feeding unit  20 A configures one of the feeding paths, the feeding unit  20 B configures another feeding path, and further, the feeding unit  20 C configures the other feeding path. The feeding unit  20 A has a feeding roller  21  extending in the X-direction. The feeding roller  21  rotates by the driving force that is generated by a driving source  25  (in the present embodiment, motor) and is capable of conveying a printing medium loaded on a loading table  22 . The loading table  22  is arranged at the rear section of the main body  2  and can be opened so that the storage state shown in  FIG. 1A  and the like changes into the open state shown in  FIG. 1B ,  FIG. 2A , and  FIG. 2B . 
     Each of the feeding unit  20 B and the feeding unit  20 C has a feeding cassette  24  that is attached detachably to the bottom section of the printing apparatus  1  from the front section and a printing medium stored in the feeding unit  24  is sent to an intermediate conveyance unit  90  provided on the rear side of the printing apparatus  1 . The intermediate conveyance unit  90  is provided with an intermediate roller  91  and an intermediate follower roller  92  opposed thereto. The conveyance path of the intermediate conveyance unit  90  includes an inner guide  93  and an outer guide  94  and in the vicinity of the intermediate roller  91 , a sheet material detection unit  80  configured to detect the presence/absence of a printing medium P is provided. The outer guide  94  is configured so as to be detachable from the printing apparatus  1  in view of processing (so-called jam processing) to remove a printing medium having caused a conveyance failure, such as a paper jam. In a case where a user opens the outer guide  94  at the time of jam processing, part of the conveyance path is exposed. 
     The conveyance unit  30  is arranged on the downstream side of the intermediate conveyance unit  90 . The conveyance unit  30  has a conveyance roller  31  extending in the X-direction. The conveyance roller  31  rotates by the driving force of a driving source  32  (in the present embodiment, motor) and conveys a printing medium fed from the feeding unit  20 A, the feeding unit  20 B, or the feeding unit  20 C along the Y-direction. A follower roller is caused to come into pressure contact with the conveyance roller  31  and a printing medium is conveyed while being sandwiched by a nip section of the conveyance roller  31  and the follower roller. 
     The discharging unit  40  is arranged on the downstream side of the conveyance unit  30 . The discharging unit  40  has a discharging roller  41  extending in the X-direction. The discharging roller  41  rotates by the driving force of the driving source  32  and discharges a printing medium that is conveyed from the conveyance unit  30 . 
     The printing unit  10  shown in  FIG. 2A  and  FIG. 2B  has a driving mechanism that causes the carriage  11  to reciprocate in a predetermined direction. The reciprocation direction of the carriage  11  is called the main scanning direction and in a case of the present embodiment, the main scanning direction is the X-axis direction. There is a case where the movement of the carriage  11  is called a (main) scan and printing an image by the print head  12  while moving the carriage  11  is called a printing scan. 
     The driving mechanism of the carriage  11  includes, for example, a guide rail that guides the movement in the main scanning direction of the carriage  11  and a belt transmission mechanism that moves the carriage  11  in the main scanning direction by transmitting the driving force from a driving source  13  (in the present embodiment, motor) to the carriage  11 . 
     It is possible to perform printing of an image onto a printing medium by the printing apparatus  1  as follows. A printing medium that is fed from the feeding unit  20 A, the feeding unit  20 B, or the feeding unit  20 C is conveyed intermittently by the conveyance unit  30  and the conveyance of the printing medium and the printing of an image onto the printing medium by the printing unit  10  are performed alternately. To explain in detail, the printing medium is conveyed by the conveyance unit  30  in the sub scanning direction and stops so that the row position at which an image is formed on the printing medium is the image printing position (specifically, directly under the ink ejection surface). Then, during the interruption of the conveyance of the printing medium, the printing scan is performed by moving the carriage  11 . Following this, the printing medium is conveyed by the conveyance unit  30  and stops so that the row position at which an image is formed next on the printing medium is the image printing position. Then, during the interruption of the conveyance of the printing medium, the printing scan is performed by moving the carriage  11 . After this, the same procedure is repeated. In this manner, it is possible to perform printing of an image on the entire printing medium. In a case where the printing of an image is completed, the printing medium is discharged by the discharging unit  40 . 
     &lt;Configuration of Sheet Material Detection Unit&gt; 
     Next, the configuration of the sheet material detection unit  80  provided in the intermediate conveyance unit  90 , which is the feature of the present embodiment, is explained by using  FIG. 3A  and  FIG. 3B .  FIG. 3A  is a perspective diagram of the configuration that combines the intermediate conveyance unit  90  configured to convey a printing medium by the intermediate conveyance roller  91  located between the outer guide  94  and the inner guide (not shown schematically), and the sheet material detection unit  80 , within the printing apparatus  1  in the usable state.  FIG. 3B  is a rear diagram in a case where the sheet material detection unit  80  in the state shown in  FIG. 3A  is seen from the rear side, showing the configuration of the sheet material detection unit  80  alone by not schematically showing the outer guide  94 . 
     The sheet material detection unit  80  has a sheet material detection lever  81  that protrudes over the conveyance path of the intermediate conveyance unit  90  and which can come into contact with a printing medium, an optical sensor  87 , and a shielding lever  82  that shields the optical path of the optical sensor  87 . As shown in  FIG. 3B , the sheet material detection lever  81  and the shielding lever  82  are swingable about an identical rotation axis  88 . By biasing a spring hooking section  81   a  of the sheet material detection lever  81  and a spring hooking section  82   a  of the shielding lever  82  with a detection lever connection spring  85 , the sheet material detection lever  81  and the shielding lever  82  swing as one unit unless the external force is applied to both the levers at the same time. Further, the sheet material detection lever  81  has a spring hooking section  81   b  at the end section thereof, which is separate from the spring hooking section  81   a , and to the spring hooking section  81   b , one end of a detection lever spring  84  is hooked. The other end of the detection lever spring  84  is hooked to a spring hooking section  96   a  of a fixed section  96  to which the sheet material detection unit  80  is attached. 
     The detection lever spring  84  biases the sheet material detection lever  81  and the shielding lever  82  described previously, which rotate integrally, in the counterclockwise direction (in  FIG. 3A , CCW direction in a case where seen in the +X-direction) with respect to the rotation axis  88 . Due to this, the shielding lever  82  abuts to the optical sensor  87  attached to the fixed section  96 . At that time, as shown in  FIG. 3A , the tip of the sheet material detection lever  81  protrudes from the outer guide  94  and blocks the conveyance path, and therefore, the sheet material detection lever  81  rotates by the printing medium that is fed. The load that is applied to the printing medium at this time is equal to the pressure of the detection lever spring  84 . 
     Next, a switching unit  83  is explained. The sheet material detection lever  81  and the shielding lever  82  that are configured as separate units and rotate integrally can rotate about the same rotation axis  88  and as shown in  FIG. 3B , are attached to the fixed section  96  at the positions shifted in the X-axis direction. Further, the switching unit  83  has a spring hooking section  83   a  and to the spring hooking section  83   a , one end of a switching spring  86  is attached. On the other hand, the other end of the switching spring  86  is attached to a spring hooking section  96   b  of the fixed section  96  and the switching spring  86  biases the switching unit  83  in the clockwise direction about the rotation axis  88  (in  FIG. 3B , CW direction in a case where seen in the −X-direction). 
     The biasing force of the switching spring  86  is larger than the total biasing force of the detection lever spring  84  and the detection lever connection spring  85 . In the state where the outer guide  94  is attached to the printing apparatus  1 , by a pushing section  94 A of the outer guide  94  shown in  FIG. 3A , the switching unit  83  shown in  FIG. 3B  is pushed in an RP direction (the same as the +Y-direction). 
       FIG. 4A  is a cross-sectional diagram of the periphery of the sheet material detection unit  80  in the printing apparatus  1  to which the outer guide  94  is attached and no printing medium is fed and  FIG. 4B  is a perspective diagram in which only the sheet material detection unit  80  at this time is extracted and shown. 
     As in  FIG. 3A  and  FIG. 3B ,  FIG. 4A  shows the usable state of the printing apparatus  1  to which the outer guide  94  is attached. In the state where the switching unit  83  pushed in the RP direction by the outer guide  94 , the switching unit  83  and the sheet material detection lever  81  are not in contact, and therefore, the sheet material detection lever  81  and the shielding lever  82  are in the state where they can swing integrally about the rotation axis  88 . Then, in a case where no printing medium exists in the conveyance path, as shown in  FIG. 4A , by the biasing force of the detection lever spring  84 , the tip of the sheet material detection lever  81  enters the conveyance path and on the other hand, the shielding lever  82  shields the optical axis of the optical sensor  87 . It is possible for a control unit  100  (see  FIG. 7 ), to be described later, to determine that there is no printing medium in the conveyance path of the intermediate conveyance unit  90  in a case of detecting the optical axis shielded by the shielding lever  82 . The position of the sheet material detection unit  80  shown in  FIG. 4A  and  FIG. 4B  is defined as “first position of the sheet material detection unit  80 ”. 
     In a case where a conveyance abnormality, such as a jam of a printing medium, has occurred in the intermediate conveyance unit  90 , a user removes the outer guide  94  from the printing apparatus  1 . Due to this, the conveyance path of the intermediate conveyance unit  90  is exposed, and as a result, it is made possible for the user to access the printing medium within the conveyance path and remove the printing medium.  FIG. 5A  is a cross-sectional diagram of the periphery of the sheet material detection unit  80  in the printing apparatus  1  from which the outer guide  94  is removed and  FIG. 5B  is a perspective diagram in which only the sheet material detection unit  80  at this time is extracted and shown. 
     By removing the mobile outer guide  94  from the main body  2  of the printing apparatus  1 , the pushing section  94 A moves in the direction in which the pushing section  94 A becomes more distant from the switching unit  83  of the sheet material detection unit  80 . At this time, the switching unit  83  is interlocked with the removal operation of the outer guide  94 . In detail, the switching unit  83  rotates about the rotation axis  88  in the clockwise direction by the biasing force of the switching spring  86 , that is, rotates in the direction in which the switching unit  83  abuts to the sheet material detection lever  81  (in  FIG. 5B , clockwise (CW) direction in a case where seen in the +X-direction) and rotates the sheet material detection lever  81 . The printing apparatus  1  is provided with a lever protection unit  95  and the sheet material detection lever  81  rotated by the switching unit  83  abuts to an abutting section  95   a  within the lever protection unit  95  and is stored in the lever protection unit  95 . Further, the shielding lever  82  rotates integrally with the sheet material detection lever  81  up to a predetermined position at which the shielding lever  82  escapes from the optical sensor  87 , but in a case where the shielding lever  82  abuts to an abutting section  96   c  of the fixed section  96 , the shielding lever  82  cannot rotate any more. Consequently, after that, only the sheet material detection lever  81  rotates independently by the switching unit  83 . The position of the sheet material detection unit  80  shown in  FIG. 5A  and  FIG. 5B  is defined as “second position of the sheet material detection unit  80 ”. 
     Next, the sheet material detection unit  80  in a case where the printing operation is started from the state shown in  FIG. 4A  and  FIG. 4B  and the printing medium P is fed from the feeding unit  20 B is explained by using  FIG. 6A  and  FIG. 6B . In a case where the printing medium P enters the conveyance path of the intermediate conveyance unit  90  and comes into contact with the tip of the sheet material detection lever  81  and presses down the sheet material detection lever  81 , the sheet material detection lever  81  and the shielding lever  82  swing integrally and the shielding lever  82  escapes from the optical sensor  87 . Because of this, the optical axis is no longer shielded by the shielding lever  82 , and as a result, in a case where the optical axis is detected, it is possible to determine that the printing medium P exists in the conveyance path of the intermediate conveyance unit  90 . The position of the sheet material detection unit  80  shown in  FIG. 6A  and  FIG. 6B  is defined as “third position of the sheet material detection unit  80 ”. At this time, as described previously, the switching unit  83  is not in contact with the sheet material detection lever  81 . Consequently, the sheet material detection lever  81  and the shielding lever  82  are made possible to swing easily because the printing medium P that is conveyed in the conveying path of the intermediate conveyance unit  90  comes into contact with the sheet material detection lever  81  or on the contrary, the printing medium P no longer comes into contact with the sheet material detection lever  81 . 
     &lt;Control Unit&gt; 
     In the following, the configuration of the control system of the printing apparatus  1  (see  FIG. 1A  and  FIG. 1B ) is explained by using  FIG. 7 .  FIG. 7  is a block diagram of the control unit  100  configured to control the printing apparatus  1 . The control unit  100  is a control circuit that controls the operation of each function unit of the printing apparatus  1 . 
     A CPU  101  controls the entire printing apparatus  1 . A controller  102  assists the CPU  101  and in accordance with detection results of various sensors  105 , controls the drive of various motors  107  and the print head  12 . 
     In a ROM  103 , various kinds of data, control programs of the CPU  101 , and the like are stored and in an EEPROM  104 , various kinds of data and the like are stored. In the EEPROM  104 , storage units  110 A to  110 C configured to store medium presence information relating to the presence/absence of a printing medium within the conveyance path, to be described later, are included. It may also be possible to adopt another storage device in place of the ROM  103  and the EEPROM  104 . 
     A driver  108  drives the various motors  107 . The various motors  107  include, for example, the motor of the driving source  25 , the motor of the driving source  32 , the motor of the driving source  13 , and the like. A driver  106  drives the print head  12 . The various sensors  105  include a sensor that detects the position of the carriage  11 , a sensor that is arranged in a conveyance path of a printing medium and which detects the front/rear ends of the printing medium, a front/rear end detection unit  34  (see  FIG. 2B ), and the sheet material detection unit  80 . 
     &lt;Storage Unit of Medium Presence Information&gt; 
     As described previously, the printing apparatus  1  has the front/rear end detection unit  34  (see  FIG. 2B ), the sheet material detection unit  80  and the like as physical sensors for detecting the presence/absence of a printing medium in the conveyance path. However, it is not possible for these sensors to detect a printing medium unless the printing medium is in direct contact with each sensor. Consequently, the printing apparatus  1  of the present embodiment stores in advance information (referred to as medium presence information) indicating whether or not there is a possibility that a printing medium exists in the conveyance path. The medium presence information is stored in a storage unit  110  of medium presence information (see  FIG. 7 ). 
     To explain in detail, in the storage unit  110 A of medium presence information, information indicating whether or not there is a possibility that a printing medium exists in the conveyance path in a case where sheet feed is performed from the feeding unit  20 A is stored. Specifically, a flag value (ON) indicating that there is a possibility of existence of a printing medium or a flag value (OFF) indicating that there is no possibility of existence of a printing medium is stored. 
     Similarly, in the storage unit  110 B of medium presence information, a flag value (ON or OFF) indicating whether or not there is a possibility that a printing medium exists in the conveyance path in a case where sheet feed is performed from the feeding unit  20 B is stored. Further, in the storage unit  110 C of medium presence information, a flag value (ON or OFF) indicating whether or not there is a possibility that a printing medium exists in the conveyance path in a case where sheet feed is performed from the feeding unit  20 C is stored. 
     As one example, a case is discussed where the printing apparatus  1  operates normally and the flag value OFF is stored in each of the storage units  110 A to  110 C of medium presence information. In this case, in the stage where the sheet feed is started from the feeding unit  20 B, the value stored in the storage unit  110 B of medium presence information is updated from OFF to ON. At this time, the flag value stored in each of the storage units  110 A and  110 B of medium presence information remains OFF and is not updated. 
     &lt;Initialization Processing of Sub Scanning System&gt; 
     The printing apparatus  1  that is activated by a user pressing down the power source button or the like selectively performs initialization processing based on signal values obtained from the various sensors  105  and the flag value stored in each of the storage units  110 A to  110 C of medium presence information. In this initialization processing, initialization processing for the printing system including the print head  12  (called initialization processing of the main scanning system) and initialization processing for the conveyance system including the conveyance path of a printing medium (called initialization processing of the sub scanning system) are included. 
     In the following, the initialization processing of the sub scanning system is explained by using  FIG. 7  and  FIG. 8 . In a case where a user turns on the power source of the printing apparatus  1 , the control unit  100  starts the initialization processing of the sub scanning system shown in  FIG. 8 . 
     At S 81 , the CPU  101  obtains information on the detection results (signal values) by the various sensors  105  and the flag value stored in each of the storage units  110 A to  110 C of medium presence information. 
     At S 82 , the CPU  101  determines whether all the conveyance paths are normal (that is, whether a printing medium exists in none of all the conveyance paths) by using the information obtained at S 81 . In the present embodiment, the CPU  101  determines that all the conveyance paths are normal in a case where the detection results by the various sensors  105  indicate that no printing medium exists in the conveyance paths and the flag value stored in each of the storage units  110 A to  110 C of medium presence information is OFF. In a case where determination results at this step are affirmative, the initialization processing of the sub scanning system is terminated normally. On the other hand, in a case where the determination results at this step are negative, the processing advances to S 83 . 
     At S 83 , the CPU  101  performs the initialization processing in accordance with the information obtained at S 81 . The correspondence relationship between the specific contents of the combination of the information having a possibility of being obtained at S 81  and the specific contents of the initialization processing that is performed at this step is determined in advance by a designer. 
     At S 84 , the CPU  101  determines whether the detection results by the various sensors  105  indicate that no printing medium exists in the conveyance paths. In a case where determination results at this step are affirmative, the processing advances to S 85 . On the other hand, in a case where the determination results at this step are negative, the series of processing is terminated (in this case, a conveyance abnormality, such as a jam, has occurred and a user is notified of a message indicating this). 
     At S 85 , the CPU  101  updates the flag value stored in the storage unit  110  of medium presence information. As a result of this step, the flag value OFF is stored in each of the storage units  110 A to  110 C of medium presence information and the initialization processing of the sub scanning system is terminated normally. 
     The position of the sheet material detection unit  80  in a case where the initialization processing of the sub scanning system is terminated normally (YES at S 82 , or in a case where the processing at S 85  is terminated) is the first position shown in  FIG. 4A  and in the optical sensor  87 , the optical axis is shielded by the shielding lever  82 . The state of the printing apparatus  1  at this time is defied as “first state”. In the first state, the detection results by the optical sensor  87  indicate that no printing medium exists in the conveyance paths (called light-shield state, OFF state and the like) and the flag value OFF is stored in each of the storage units  110 A to  110 C of medium presence information (see  FIG. 10 ). 
     &lt;Sheet Feed Preparation Processing&gt; 
     In the following, processing before sheet feed is started (referred to as sheet feed preparation processing), which is performed in the printing apparatus  1  in the first state, is explained by using  FIG. 6A  and  FIG. 6B ,  FIG. 9 , and  FIG. 10 . 
     After the initialization processing of the sub scanning system described previously is terminated, in a case where the printing apparatus  1  receives instructions to start printing by receiving a print jog or the like, the sheet feed preparation processing for feeding a printing medium from the designated feeding unit among the feeding units  20 A to  20 C is performed. In the following, explanation is given by taking a case as an example where a printing medium is fed from the feeding unit  20 B. 
     At S 91 , the CPU  101  performs determination of successive sheet feed. Specifically, the CPU  101  determines whether the next page is in the sheet feed state. In a case where determination results at this step are affirmative, the processing advances to S 92  and on the other hand, in a case where the determination results are negative, the processing advances to S 93 . The reason the determination of successive sheet feed is performed at this step is that the series of sheet feed preparation processing shown in  FIG. 9  is performed not only after the initialization processing of the sub scanning system shown in  FIG. 8  is performed but also before the successive sheet feed is performed. 
     At S 92 , the CPU  101  performs a series of processing for successive sheet feed (referred to as successive sending sequence). 
     At S 93 , the CPU  101  determines whether the flag value stored in the storage unit  110 B of medium presence information is OFF and the detection results by the optical sensor  87  indicate the ON (light-receiving) state. In a case where determination results at this step are affirmative, the series of processing is terminated and on the other hand, in a case where the determination results are negative, the processing advances to S 94 . For example, in a case where the printing apparatus  1  is in the first state described previously, the flag value stored in the storage unit  110 B of medium presence information is OFF and the detection results by the optical sensor  87  indicate the OFF (light-shielded) state. Consequently, in this case, the determination results at S 93  are negative and the processing advances to S 94 . 
     At S 94 , the CPU  101  updates the flag value stored in the storage unit  110 B of medium presence information. As a result of this updating, the flag value stored in the storage unit  110 B of medium presence information is changed from OFF to ON. 
     After S 94 , the sheet feed of the printing medium P from the feeding unit  20 B is started. 
     In a case where the fed printing medium P passes the sheet material detection unit  80  including the sheet material detection lever and the like, the sheet material detection lever  81  and the shielding lever  82  swing integrally and the position of the sheet material detection unit  80  changes to the third position (see  FIG. 6A ) described previously. At this time, the shielding lever  82  has escaped from the optical sensor  87  and the detection results by the optical sensor  87  indicate the ON (light-receiving) state where the printing medium P exists in the conveyance path. The state of the printing apparatus  1  in a case where the flag value stored in the storage unit corresponding to the designated feeding unit is ON and the detection results by the optical sensor  87  indicate the ON state is defined as “third state”. In a case also where a conveyance abnormality, such as a jam, occurs before the printing medium P being fed passes the sheet material detection unit  80  although the sheet material detection unit  80  has been reached, the detection results by the optical sensor  87  indicate the ON state, and therefore, the state of the printing apparatus  1  is the third state similarly. 
     In the present embodiment, the determination of whether or not a conveyance abnormality has occurred in the conveyance path is performed by using a sensor and control different from the sensor and the control described previously. 
     &lt;Outer Guide Unattached Error&gt; 
     In the following, error processing (referred to as outer guide unattached error processing) in a case where the printing apparatus  1  receives instructions to start printing in the state where the outer guide  94  is removed from the printing apparatus  1  in the first state is explained by using  FIG. 9 . In the following, as in the explanation of the sheet feed preparation processing described previously, explanation is given by taking a case as an example where the feeding unit  20 B is designated as the feeding source unit. 
     The processing at S 91  and S 92  is the same as the processing described previously. 
     At S 93 , the CPU  101  determines whether the flag value stored in the storage unit  110 B of medium presence information is OFF and the detection results by the optical sensor  87  indicate the ON (light-receiving) state. As described previously, the sheet feed preparation processing is performed after the initialization processing of the sub scanning system, and therefore, originally, the flag value stored in the storage unit  110 B of medium presence information should be OFF and the detection results by the optical sensor  87  should indicate the OFF (light-shielded) state. However, in the case of this example, as shown in  FIG. 5A  and  FIG. 5B , as a result of the outer guide  94  being removed, the position of the sheet material detection unit  80  is the second position and the detection results of the optical sensor  87  indicate the ON (light-receiving) state. Consequently, the determination results at S 93  are affirmative and the printing apparatus  1  enters the error state where the outer guide is not attached. At this time, the CPU  101  notifies a user of the error state by displaying a message to the effect that the outer guide  94  is not attached and the like. The state of the printing apparatus  1  in a case where the flag value stored in the storage unit  110 B of medium presence information is OFF and the detection results by the optical sensor  87  indicate the ON (light-receiving) state is defined as “second state”. 
       FIG. 10  is a table in which the state information on the printing apparatus  1  is stored, which is associated with each of combinations of the state indicated by the detection results by the optical sensor  87  and the flag value stored in the storage unit  110 B of medium presence information. 
     Effects and the Like 
     As described above, in the present embodiment, in a case where the outer guide  94  is removed from the printing apparatus  1  in the jam processing and the like, the sheet material detection lever  81  is stored in the lever protection unit  95  provided in the printing apparatus  1 . Due to this, it is possible to prevent the erroneous damage to the sheet material detection lever  81  in a case where the outer guide  94  is removed from the printing apparatus  1 . Further, even in a case where the removed outer guide  94  drops accidentally or an impact is applied to the outer guide  94 , it is possible to maintain the printing medium detection function because the sheet material detection unit  80  is located in the printing apparatus  1 . 
     OTHER EMBODIMENTS 
     Embodiment(s) of the present disclosure can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as a ‘non-transitory computer-readable storage medium’) to perform the functions of one or more of the above-described embodiment(s) and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s) and/or controlling the one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may comprise one or more processors (e.g., central processing unit (CPU), micro processing unit (MPU)) and may include a network of separate computers or separate processors to read out and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, a memory card, and the like. 
     According to one embodiment of the present invention, it is possible to provide a conveyance apparatus whose detection unit of a printing medium is unlikely to be damaged. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. 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. 
     This application claims the benefit of Japanese Patent Application No. 2021-011677, filed Jan. 28, 2021, which is hereby incorporated by reference wherein in its entirety.