Patent Publication Number: US-2023150782-A1

Title: Sheet conveying device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2021-186464, filed Nov. 16, 2021, the entire contents of which are incorporated herein by reference. 
     FIELD 
     Embodiments described herein relate to a sheet conveying device such as, for example, a printer or the like. 
     BACKGROUND 
     An image processing apparatus includes a sheet conveying device. The sheet conveying device includes a tray on which a plurality of sheets are stacked. The device also has a pickup roller to remove a sheet from the tray and a raising and lowering mechanism that raises a part of the tray. The sheet conveying device may include a detecting mechanism that detects when the tray is raised and when a sheet reaches the pickup roller. In general, sheet conveying device is required to be small in size. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic view of an image processing apparatus including a sheet conveying device according to a first embodiment. 
         FIG.  2    is a perspective view of a sheet conveying device according to a first embodiment. 
         FIG.  3    is a perspective view depicting aspects of a sheet conveying device according to a first embodiment. 
         FIG.  4    is a perspective view depicting aspects of a sheet conveying device according to a first embodiment. 
         FIG.  5    is a perspective view depicting aspects of a sheet conveying device according to a first embodiment. 
         FIG.  6    is an enlarged view of depicting aspects of a sheet conveying device according to a first embodiment. 
         FIGS.  7 A and  7 B  depict aspects related to an operation of a sheet conveying device according to a first embodiment. 
         FIG.  8    is a perspective view of a portion of an image processing apparatus to which a biasing unit is attached. 
         FIG.  9    is a perspective view of a portion of an image processing apparatus from which a biasing unit has been detached. 
         FIG.  10    is a perspective view of a part of a sheet conveying device according to a second embodiment. 
         FIGS.  11 A and  11 B  depict aspects related to an operation of a sheet conveying device according to a second embodiment. 
         FIG.  12    is a perspective view depicting aspects of a sheet conveying device according to a third embodiment. 
         FIGS.  13 A and  13 B  depict aspects related to an operation of a sheet conveying device according to a third embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     According to one embodiment, a sheet conveying device sheet conveying device includes a tray on which sheets can be stacked, a pickup roller configured to convey sheets from the tray to a sheet conveyance path, and a movement mechanism configured to move the tray between a raised position at which sheets on the tray come into contact with the pickup roller and a lowered position that is lower than the raised position. A holder is configured to hold the pickup roller such that the pickup roller displaces upward when pushed up by sheets on the tray. A biasing unit is configured to apply a biasing force to the holder in a direction pushing the pickup roller downward towards the tray. A detecting mechanism is configured to detect when the pickup roller is displaced upward by the sheets on the tray. The detecting mechanism includes a detection unit that moves between a reference position and a detection position according to displacement of the holder upwards or downwards and a sensor that is configured to detect the detection unit at the detection position. 
     Hereinafter, sheet conveying devices according to certain example embodiments will be described with reference to the drawings. In the drawings, the same or corresponding components are denoted by the same reference numerals unless otherwise specified. 
     First Embodiment 
       FIG.  1    is a schematic view showing a configuration example of an image processing apparatus including the sheet conveying device according to the first embodiment. 
     As shown in  FIG.  1   , an image processing apparatus  100  includes a control panel  1 , a scanner unit  2 , a printer unit  3 , a sheet feeding unit  4 , a conveying unit  5 , a manual feeding unit  10  (sheet conveying device), and a control circuit  60 . 
     In the following description, when referring to relative positions in the image processing apparatus  100 , an Xp direction, an Xm direction, a Yp direction, a Ym direction, a Zp direction, and a Zm direction shown in the drawing may be used. The Xp direction is a direction from left to right when standing in front of the image processing apparatus  100  (in front of the paper of  FIG.  1   ). The Xm direction is a direction opposite to the Xp direction. The Yp direction is a direction from back to front of the image processing apparatus  100 . The Ym direction is a direction opposite to the Yp direction. The Zp direction is a vertically upward direction. The Zm direction is a vertically downward direction. 
     A plane orthogonal to the X direction is referred to as a YZ plane, a plane orthogonal to the Y direction is referred to as a ZX plane, and a plane orthogonal to the Z direction is referred as an XY plane. 
     When a user manipulates the control panel  1 , the image processing apparatus  100  can be operated. 
     The scanner unit  2  reads image information from an object to be copied based on brightness and darkness of reflected light. The scanner unit  2  outputs the image information that has been read to the printer unit  3 . 
     The printer unit  3  forms, based on the image information from the scanner unit  2  or the outside, an image on the sheet S. 
     The printer unit  3  forms an output image (toner image) with a developer containing toner. The printer unit  3  transfers the toner image onto a front surface of the sheet S. The printer unit  3  applies heat and pressure to the toner image on the front surface of the sheet S to fix the toner image on the sheet S. 
     The sheet feeding unit  4  feeds the sheets S one after one to the printer unit  3  at a timing at which the printer unit  3  forms the toner image. 
     The sheet feeding unit  4  includes a plurality of sheet feeding cassettes  20  and a plurality of cassette sheet feeding units  21 . 
     The plurality of sheet feeding cassettes  20  stores the sheets S of various sizes. In the example shown in  FIG.  1   , the three sheet feeding cassettes  20  are provided in three stages. 
     The plurality of cassette sheet feeding units  21  are disposed above end portions of respective sheet feeding cassettes  20  in the Xp direction. Each of the cassette sheet feeding units  21  includes a pickup roller  212  (conveying roller), a sheet feeding roller  211 , and a separation roller  213 . 
     The pickup roller  212  conveys the sheet S for image formation from the sheet feeding cassette  20  to a nip portion between the sheet feeding roller  211  and the separation roller  213 . The pickup roller  212  is an example of the conveying roller that conveys sheets S in the conveyance direction from an upper side of the stacked sheets in a sheet feeding cassette  20 . 
     The sheet feeding roller  211  conveys the sheet S conveyed from the nip portion to the conveying unit  5 . 
     The separation roller  213  serves to separate one sheet S from the other sheets when a plurality of sheets S are conveyed at the same time. 
     The conveying unit  5  includes conveying rollers  23  and registration rollers  24 . The conveying unit  5  conveys the sheet S fed from the sheet feeding unit  4  to the registration rollers  2 . 
     The registration rollers  24  convey the sheet S at a timing corresponding to that at which the printer unit  3  transfers the toner image on the sheet S. 
     The conveying rollers  23  abut a top end (leading edge) of the sheet S in the conveyance direction against a nip N between the registration rollers  24 . The conveying rollers  23  adjust a position of the top end of the sheet S in the conveyance direction by bending the sheet S. 
     The registration rollers  24  align the top end of the sheet S at the nip N. The registration rollers  24  then convey the sheet S to a transferring unit  28 . 
     The conveying unit  5  includes conveyance paths  301 ,  302 ,  303 , and  304 . 
     The printer unit  3  includes a plurality of image forming units  25 , a plurality of exposure units  26 , an intermediate transferring belt  27 , a transferring unit  28 , a fixing device  29 , and a transferring belt cleaning unit  35 . 
     Four image forming units  25  are disposed side by side in the Xp direction. 
     Each of the plurality of image forming units  25  forms a toner image on the intermediate transferring belt  27  to be transferred to the sheet S. 
     Each of the plurality of image forming units  25  includes a photosensitive drum  7 . The plurality of image forming units  25  form yellow, magenta, cyan, and black toner images on respective photosensitive drums  7 . 
     A charger, a developing device  8 , a primary transfer roller, a cleaning unit, and a static eliminator are disposed around each of the photosensitive drums  7 . The primary transfer roller faces the photosensitive drum  7 . The intermediate transferring belt  27  is sandwiched between the primary transfer roller and the photosensitive drum  7 . The exposure units  26  are disposed below the chargers and the developing devices  8 . 
     Toner cartridges  33  are disposed above the image forming units  25 , respectively. Colors of toner stored in each of the toner cartridges  33  are different. The four toner cartridges  33  in this example store yellow, magenta, cyan, and black toners, respectively. 
     The toner in each of the toner cartridges  33  is fed to a corresponding one of the lower image forming units  25  by a toner supplying pipe or the like. 
     The exposure units  26  irradiate surfaces of the charged photosensitive drums  7  with laser light. Emission of the laser light is controlled based on the image information. The exposure units  26  may emit LED light instead of the laser light in some examples. In the example shown in  FIG.  1   , the exposure units  26  are disposed below the plurality of the image forming units  25 . 
     The image information corresponding to yellow, magenta, cyan, and black color channels is fed to the exposure units  26 , respectively. 
     The exposure units  26  form electrostatic latent images based on the image information on the surfaces of the photosensitive drums  7 . 
     The intermediate transferring belt  27  comprises an endless belt (a loop). Tension is applied to the intermediate transferring belt  27  by a plurality of rollers that abut against an inner circumferential surface of the intermediate transferring belt  27 . The intermediate transferring belt  27  is stretched flat. The inner circumferential surface of the intermediate transferring belt  27  abuts against a supporting roller  281  at a position in the Xp direction farthest in a stretching direction. The inner circumferential surface of the intermediate transferring belt  27  abuts against a transferring belt roller  32  at a position in the Xm direction farthest in the stretching direction. 
     The supporting roller  281  constitutes a part of the transferring unit  28 . The supporting roller  281  guides the intermediate transferring belt  27  to a secondary transfer position. 
     The transferring belt roller  32  guides the intermediate transferring belt  27  to a cleaning position. 
     On a lower surface side of the intermediate transferring belt  27  shown in the drawing, the image forming units  25  other than the primary transfer rollers are disposed in the Xp direction. The image forming units  25  are disposed at intervals in a region between the transferring belt roller  32  and the supporting roller  281 . 
     When the toner images reach a primary transfer position, a transfer bias is applied to the primary transfer roller of each of the image forming units  25 . Each of the primary transfer rollers transfers (primary transfers) the toner image on the surface of a corresponding one of the photosensitive drums  7  to the intermediate transferring belt  27 . 
     In the intermediate transferring belt  27 , the transferring unit  28  is disposed at a position closest to the image forming units  25  in the Xp direction. 
     The transferring unit  28  includes the supporting roller  281  and a secondary transfer roller  282 . The intermediate transferring belt  27  is sandwiched between the secondary transfer roller  282  and the supporting roller  281 . A position at which the secondary transfer roller  282  abuts against the intermediate transferring belt  27  is referred to as the secondary transfer position. 
     The transferring unit  28  transfers, onto the front surface of the sheet S, the toner images on the intermediate transferring belt  27  at the secondary transfer position. The transferring unit  28  applies a transfer bias at the secondary transfer position. The transferring unit  28  transfers the toner images on the intermediate transferring belt  27  to the sheet S by application of the transfer bias. 
     The fixing device  29  applies heat and pressure to the sheet S. The fixing device  29  fixes, by the heat and pressure, the toner images to the sheet S. The fixing device  29  is disposed above the transferring unit  28 . 
     The transferring belt cleaning unit  35  faces the transferring belt roller  32 . The transferring belt cleaning unit  35  contacts the intermediate transferring belt  27 . The transferring belt cleaning unit  35  scrapes off toner on the surface of the intermediate transferring belt  27 . 
     The conveyance paths  301  and  302  for conveying the sheet S from a lower side to an upper side are formed between the registration rollers  24  and the transferring unit  28  and between the transferring unit  28  and the fixing device  29  in this order. The conveyance path  303  for discharging the sheet S in the horizontal direction is formed between the fixing device  29  and a sheet discharging port. 
     A conveyance direction switching unit  31  that switches the conveyance direction of the sheet S is provided above the fixing device  29 . 
     The conveyance path  304  for conveying the sheet S from the conveyance direction switching unit  31  back to the registration rollers  24  is formed inside the printer unit  3  on an Xp direction side of the conveyance paths  301  and  302 . The conveyance path  304  is used, for example, for reversing the sheet S having an image already formed on the front surface thereof and feeding the sheet S to the registration rollers  24  when duplex (two-sided) printing is performed. 
     Each of the conveyance paths  301 ,  302 ,  303 , and  304  includes conveyance guiding portions that face each other with the sheet S passing therebetween, and a conveying roller provided as necessary. 
     The manual feeding unit  10  can be used to feed sheets S the printer unit  3 . The manual feeding unit  10  is an example of the sheet conveying device. 
     The manual feeding unit  10  includes a manual sheet feeding unit  11 , a manual feeding tray  12 , a raising and lowering mechanism  40 , a holder  114  (see  FIG.  2   ), a biasing unit  115  (see  FIG.  2   ), and a tray up detecting mechanism  116  (see  FIG.  2   ). 
     The manual sheet feeding unit  11  includes a pickup roller  112  (conveying roller), a sheet feeding roller  111 , and a separation roller  113 . The manual sheet feeding unit  11  separates and feeds the sheets S placed on the manual feeding tray  12 , and conveys the sheets S toward the registration rollers  24 . 
     The pickup roller  112  has the same configuration as that of the pickup roller  212  in the cassette sheet feeding unit  21 . The sheet feeding roller  111  has the same configuration as that of the sheet feeding roller  211  in the cassette sheet feeding unit  21 . The separation roller  113  has the same configuration as that of the separation roller  213  in the cassette sheet feeding unit  21 . The pickup roller  112  is an example of a conveying roller that conveys a sheet S in the conveyance direction from an upper surface of a stack or the like. 
     The manual feeding tray  12  is pivotable around an axis along the Y direction. When the manual feeding tray  12  is to be used the manual feeding tray  12  is pivoted clockwise in  FIG.  1    and opened as indicated by the solid line depiction of the manual feeding tray  12 . Sheets S of various sizes can be placed on the opened manual feeding tray  12 . 
     When the manual feeding tray  12  is not being used, the manual feeding tray  12  van be pivoted counterclockwise in  FIG.  1    and stored in or against a side portion of the printer unit  3 , as indicated by a two-dot chain line depiction in  FIG.  1   . 
       FIG.  2    is a perspective view of the manual feeding unit  10 .  FIG.  3    is a perspective view of a part of the manual feeding unit  10 .  FIG.  4    is a perspective view of another part of the manual feeding unit  10 .  FIG.  5    is a perspective view of still another part of the manual feeding unit  10 .  FIG.  6    is a perspective view of an enlarged part of the manual feeding unit  10 . 
     As shown in  FIG.  2   , the manual feeding tray  12  includes a main body portion  121 , a raising and lowering plate  13  (“tray  13 ”), and a biasing member  14 . 
     The main body portion  121  is formed in a plate shape. 
     The tray  13  is provided on the main body portion  121 . An upper surface of the tray  13  is a surface on which the sheets S are placed. The tray  13  is an example of a tray on which a plurality of sheets S can be stacked. 
     A supporting portion  123  that is pivotable and supports the tray  13  is provided on the main body portion  121 . The supporting portion  123  is disposed on an axis C 1 . The axis C 1  is parallel to the Y direction. The tray  13  is engaged with the supporting portion  123 . The tray  13  is pivotable around the axis C 1 . 
     As shown in  FIG.  1   , the raising and lowering mechanism  40  is provided on a device body of the printer unit  3 . 
     With the manual feeding tray  12  in an opened state, the raising and lowering mechanism  40  moves the tray  13  between a raised position and a lowered position by pivoting the tray  13  around the axis C 1  (see  FIG.  2   ). The raised position is a position at which a top end of the tray  13  is farthest from the main body portion  121 . At the raised position, a sheet on the tray  13  is in contact with (or close to) the pickup roller  112 . The lowered position is a position at which the top end of the tray  13  approaches the main body portion  121  most closely. The raising and lowering mechanism  40  may, for example, raise and lower the tray  13  with a driving motor. 
     As shown in  FIG.  3   , the holder  114  is rotatable and holds the pickup roller  112 . The holder  114  includes an upper plate  114   a,  a first end plate  114   b,  and a second end plate  114   c.  The upper plate  114   a  is formed in a rectangular shape when viewed from the Z direction. A protrusion  114   d  protruding in the Zp direction is formed on an upper surface of the upper plate  114   a.  A top end of a pressing body  131  can abut against the protrusion  114   d.  The holder  114  is pressed at the protrusion  114   d  in a push-down direction by the pressing body  131 . 
     A portion (protrusion  114   d ) where the top end of the pressing body  131  abuts against the holder  114  is on the ZX plane including the pickup roller  112 , and overlaps with the pickup roller  112  when viewed from a direction (Z direction) of a biasing force. At least a part of the abutting portion of the pressing body  131  may be on the ZX plane including the pickup roller  112 . The abutting portion of the pressing body  131  may overlap with the pickup roller  112  when viewed from the Z direction. 
     The first end plate  114   b  hangs down from an end portion of the upper plate  114   a  in the Yp direction. The second end plate  114   c  hangs down from an end portion of the upper plate  114   a  in the Ym direction. The first end plate  114   b  and the second end plate  114   c  are along the ZX plane. 
     The first end plate  114   b  and the second end plate  114   c  are formed with a bearing portion  114   e  that is rotatable and supports a rotary shaft  112 A of the pickup roller  112 . The rotary shaft  112 A of the pickup roller  112  is along the Y direction. 
     The holder  114  is supported on the device body of the printer unit  3  by a holder shaft  120  along the Y direction. The holder  114  is pivotable around an axis C 2  (see  FIG.  4   ) of the holder shaft  120 . The holder shaft  120  is located at a position away from the rotary shaft  112 A of the pickup roller  112  when viewed from the Y direction. The holder  114  can displace the pickup roller  112  by pivoting around the axis C 2  of the holder shaft  120 . The holder  114  can change a height position of the pickup roller  112  by pivoting around the axis C 2  (see  FIGS.  7 A and  7 B ). 
     As shown in  FIGS.  4  and  5   , the biasing unit  115  applies a force to the holder  114  in a direction of pushing down the pickup roller  112 . 
     The biasing unit  115  includes the pressing body  131 , a biasing member  132 , and a supporting portion  133 . 
     As shown in  FIG.  5   , the pressing body  131  includes a main body portion  131   a  and a flange portion  131   b.  The pressing body  131  is displaceable in a length direction of the main body portion  131   a.  The main body portion  131   a  is formed in a rod shape elongated in the Z direction. The main body portion  131   a  is inserted into the biasing member  132 . 
     The flange portion  131   b  protrudes outward in a radial direction of the main body portion  131   a  at an intermediate portion of the main body portion  131   a  along the length direction. The flange portion  131   b  is formed in a plate shape perpendicular to the length direction of the main body portion  131   a.  The flange portion  131   b  is engageable with a lower end of the biasing member  132 . 
     The biasing member  132  is inserted into the main body portion  131   a.  The lower end of the biasing member  132  is engaged with an upper surface of the flange portion  131   b.  The biasing member  132  is, for example, a coil spring. The biasing member  132  applies a force to the flange portion  131   b  in a direction of approaching the holder  114 . The pressing body  131  is biased in the direction of approaching the holder  114 . 
     As shown in  FIG.  4   , the supporting portion  133  includes a base board  133   a,  a first engagement portion  133   b,  and a second engagement portion  133   c.  The base board  133   a  is formed in a plate shape along the YZ plane. The first engagement portion  133   b  is formed in a plate shape along the XY plane. The flange portion  131   b  of the pressing body  131  is engageable with an upper surface of the first engagement portion  133   b.    
     The second engagement portion  133   c  is located at a position separated from the first engagement portion  133   b  in the Zp direction. The second engagement portion  133   c  is formed in a plate shape along the XY plane. An upper end of the biasing member  132  is engageable with a lower surface of the second engagement portion  133   c.  The biasing member  132  takes a reaction force to the second engagement portion  133   c  and applies the force to the flange portion  131   b  in the direction of approaching the holder  114 . 
     As shown in  FIG.  5   , the tray up detecting mechanism  116  includes an operation unit  141 , an actuator  142 , a detection unit  143 , and a sensor  144 . The tray up detecting mechanism  116  is one example of a “detecting mechanism”. The tray up detecting mechanism  116  detects that the sheets S push up the pickup roller  112 . 
     The operation unit  141  extends in the Yp direction from an outer surface of the first end plate  114   b  (the surface facing the Yp direction). The operation unit  141  is formed in a long plate shape elongated in the Yp direction. For example, the operation unit  141  is curved around the axis C 2  of the holder shaft  120  (see  FIG.  4   ). 
     As shown in  FIG.  6   , the actuator  142  includes a shaft portion  142   a  and a cam plate portion  142   b.  The shaft portion  142   a  is elongated in the Y direction. The actuator  142  is pivotable around an axis C 3  of the shaft portion  142   a.    
     The cam plate portion  142   b  protrudes outward in a radial direction of the shaft portion  142   a  from an outer peripheral surface of the shaft portion  142   a.  The cam plate portion  142   b  is formed in a plate shape perpendicular to the length direction of the shaft portion  142   a.  An outer surface of the cam plate portion  142   b  is a cam surface  142   c.    
     As shown in  FIG.  5   , the detection unit  143  protrudes outward in the radial direction of the shaft portion  142   a  from the outer peripheral surface of the shaft portion  142   a.  The detection unit  143  is formed in a plate shape perpendicular to the length direction of the shaft portion  142   a.  The detection unit  143  pivots in the same direction as that of the actuator  142  in conjunction with the actuator  142 . The detection unit  143  is switchable between a reference position and a detection position by pivoting in conjunction with the actuator  142 . 
     For example, a photo-interrupter is used as the sensor  144 . The sensor  144  includes a light-emitting unit  144   a  and a light-receiving unit  144   b.  The light-emitting unit  144   a  and the light-receiving unit  144   b  face each other. When the detection unit  143  is at the reference position, the detection unit  143  does not block light from the sensor  144 . When the detection unit  143  pivots together with the actuator  142  and reaches the detection position, the detection unit  143  blocks the light. When the light is blocked, the sensor  144  sends a detection signal to the control circuit  60  (see  FIG.  1   ). 
     Next, operations of the image processing apparatus  100  will be described. First, a print operation will be described. 
     In the image processing apparatus  100 , conditions (settings) such as the type of sheets S on which an image is to be formed and the number of sheets to be printed can be set based on user operations at the control panel  1  or by an external signal. Image formation is started according to a print start signal. Image information (print data) is sent to the printer unit  3  by the scanner unit  2  reading an object to be copied or from the outside. The printer unit  3  supplies the sheets S from the sheet feeding unit  4  or the manual feeding unit  10  to the registration rollers  24  based on a control signal generated by the control circuit  60  in response to the condition settings and the reception of the print start signal. A case where the sheets S are fed from the manual feeding unit  10  will be described. 
     When the print start signal is received, the control circuit  60  performs control to start sheet feeding from the manual feeding unit  10  for the image formation. 
     Each image forming unit  25  forms an electrostatic latent image on the respective photosensitive drum  7  based on image information corresponding to each color. The electrostatic latent image is developed by the developing device  8 . Therefore, a toner image corresponding to the electrostatic latent image is formed on the surface of each photosensitive drum  7 . 
     Each toner image is transferred to the intermediate transferring belt  27  by the respective transfer roller. As the intermediate transferring belt  27  moves, the toner images are sequentially superimposed on one another without causing a color shift, and these superimposed toner images are sent to the transferring unit  28 . 
     The sheet S is fed from the registration rollers  24  to the transferring unit  28  to meet the toner image to be transferred. The toner images that reach the transferring unit  28  are transferred to the sheet S. The transferred toner images are fixed to the sheet S by the fixing device  29 . Images are thus formed on the sheet S (a sheet S has been printed). 
     Next, an operation of the manual feeding unit  10  will be described. 
     The user places sheets S on the tray  13  (see  FIG.  2   ) of the manual feeding tray  12  (see  FIG.  1   ). The number of sheets S placed on the tray  13  corresponds to the total number of sheets S the user wishes to be printed. 
     When the tray  13  (see  FIG.  2   ) reaches the raised position, the sheets S placed on the tray  13  come into contact with the pickup roller  112  (see  FIG.  3   ) and a force from the sheets S is applied in a push-up direction to the pickup roller  112 . 
     As shown in  FIGS.  7 A and  7 B , when the pickup roller  112  (see  FIG.  5   ) is pushed up, the holder  114  pivots around the axis C 2  of the holder shaft  120 , and the protrusion  114   d  pushes up the pressing body  131 . When the pressing body  131  is pushed up, the biasing member  132  is compressed. The pressing body  131  applies a force to the holder  114  in a push-down direction by an elastic force of the biasing member  132 . 
     As shown in  FIG.  5   , when the holder  114  pivots around the axis C 2  of the holder shaft  120 , the operation unit  141  also pivots around the axis C 2 . As shown in  FIG.  6   , the operation unit  141  is in contact with the cam surface  142   c  of the cam plate portion  142   b  and pivots the actuator  142  around the axis C 3 . 
     The detection unit  143  pivots together with the actuator  142  and moves from the reference position to the detection position. 
     When the detection unit  143  reaches the detection position, the detection unit  143  blocks the detection light of the sensor  144 . The sensor  144  detects that the detection unit  143  reaches the detection position. The sensor  144  sends a detection signal to the control circuit  60  (see  FIG.  1   ). The control circuit  60  then sends control signals to each component of the image processing apparatus  100  to convey the sheet S from the manual feeding tray  12  to the conveying unit  5 , and performs the print operation described above. 
       FIG.  8    is a perspective view of an apparatus body  100   a  of the image processing apparatus  100  to which the biasing unit  115  is attached.  FIG.  9    is a perspective view of the apparatus body  100   a  from which the biasing unit  115  has been detached. 
     As shown in  FIG.  8   , the biasing unit  115  is attachable to the apparatus body  100   a.  As shown in  FIG.  9   , the biasing unit  115  may be detachable from the apparatus body  100   a  in some examples. When the biasing unit  115  is attachable to and detachable from the apparatus body  100   a,  maintenance may be easier. When the biasing unit  115  is attachable to and detachable from the apparatus body  100   a,  a specification for the manual feeding unit  10  is more easily changed by replacing of the biasing member  132  or the like. 
     In the manual feeding unit  10 , since the biasing unit  115  applies the biasing force to the holder  114  on the ZX plane including the pickup roller  112 , a structure of the manual feeding unit  10  can be simplified as compared with that when a biasing unit is more separated from a pickup roller. In addition, since the biasing unit  115  applies the biasing force to the holder  114  at the position of overlapping the pickup roller  112  when viewed from the direction (Z direction) of the biasing force, the structure of the manual feeding unit  10  can be simplified as compared with that when the biasing unit is more separated from the pickup roller. Since the manual feeding unit  10  has a simpler structure, the manual feeding unit  10  is advantageous in terms of size reduction and space-saving. 
     Since the biasing unit  115  applies the biasing force to the holder  114  on the ZX plane including the pickup roller  112 , a pressing force of the pressing body  131  is efficiently transmitted to the pickup roller  112 . In addition, since the biasing force is applied to the holder  114  at the position of overlapping the pickup roller  112  when viewed from the direction (Z direction) of the biasing force, the pressing force by the pressing body  131  is efficiently transmitted to the pickup roller  112 . 
     The tray up detecting mechanism  116  includes the operation unit  141  and the actuator  142 . The actuator  142  can switch between the reference position and the detection position of the detection unit  143 . Since the detection unit  143  is switched between the reference position and the detection position by an operation of the actuator  142 , the detection unit  143  can reliably operate and an erroneous operation can be prevented. 
     Since the detection unit  143  is provided on the shaft portion  142   a  of the actuator  142 , the detection unit  143  can reliably operate. 
     The biasing unit  115  includes the pressing body  131 , the biasing member  132 , and the supporting portion  133 . Since a structure of the biasing unit  115  is simple, miniaturization of the biasing unit  115  can be achieved. 
     Second Embodiment 
       FIG.  10    is a perspective view of a part of the sheet conveying device according to the second embodiment. 
     As shown in  FIG.  10   , a manual feeding unit  210  includes a tray up detecting mechanism  216  instead of the tray up detecting mechanism  116 . 
     The tray up detecting mechanism  216  includes a detection unit  243  and a sensor  244 . The tray up detecting mechanism  216  is one example of a “detecting mechanism”. 
     The detection unit  243  has a similar configuration to that of the operation unit  141  (see  FIG.  3   ) in the manual feeding unit  10  according to the first embodiment. When the holder  114  pivots around the axis C 2 , the detection unit  243  also pivots around the axis C 2 . 
     For example, the sensor  244  is a photo-interrupter including the light-emitting unit  144   a  and the light-receiving unit  144   b.    
     As shown in  FIGS.  11 A and  11 B , when the pickup roller  112  (see  FIG.  10   ) is pushed up, the holder  114  pivots around the axis C 2  of the holder shaft  120 , and the protrusion  114   d  pushes up the pressing body  131 . The pressing body  131  applies a force to the holder  114  in a push-down direction by the biasing member  132 . 
     As the holder  114  pivots around the C 2 , the detection unit  243  also pivots around the axis C 2 . The detection unit  243  moves from a reference position to a detection position. When the detection unit  243  reaches the detection position, the detection unit  243  blocks light from the sensor  244 . The sensor  244  sends a detection signal to the control circuit  60  (see  FIG.  1   ). The control circuit  60  sends control signals to each component of the image processing apparatus  100  to convey the sheet S from the manual feeding tray  12  to the conveying unit  5 , and performs the print operation. 
     The manual feeding unit  210  includes fewer components for the tray up detecting mechanism  216  and has a simpler structure. Since the manual feeding unit  210  has a simple structure, the manual feeding unit  210  is advantageous in terms of size reduction and space-saving. 
     Third Embodiment 
       FIG.  12    is a perspective view of a sheet conveying device according to a third embodiment. 
     As shown in  FIG.  12   , a manual feeding unit  310  includes a tray up detecting mechanism  316  instead of the tray up detecting mechanism  116 . 
     The tray up detecting mechanism  316  includes a detection unit  343  and a sensor  344 . The tray up detecting mechanism  316  is one example of a “detecting mechanism”. 
     The detection unit  343  is provided on an upper end portion of the pressing body  131 . The detection unit  343  is formed in a plate shape along the ZX plane. The detection unit  343  protrudes outward in a radial direction from an outer peripheral surface of the main body portion  131   a.  The detection unit  343  moves up and down together with the pressing body  131 . 
     For example, the sensor  344  is a photo-interrupter including the light-emitting unit  144   a  and the light-receiving unit  144   b.    
     As shown in  FIGS.  13 A and  13 B , when the pickup roller  112  is pushed up, the holder  114  pivots around the axis C 2  of the holder shaft  120 , and the protrusion  114   d  pushes up the pressing body  131 . The pressing body  131  applies a force to the holder  114  in a push-down direction by the biasing member  132 . 
     By raising the pressing body  131 , the detection unit  343  moves from a reference position to a detection position. When the detection unit  343  reaches the detection position, the detection unit  343  blocks light from the sensor  344 . The sensor  344  sends a detection signal to the control circuit  60  (see FIG.  1 ). The control circuit  60  sends control signals to each component of the image processing apparatus  100  to convey the sheet S from the manual feeding tray  12  to the conveying unit  5 , and performs a print operation. 
     Since the manual feeding unit  310  is at a position at which the detection unit  343  and the sensor  344  are close to the holder  114 , a reduction of a size of the manual feeding unit  310  can be achieved. 
     According to at least one embodiment described above, a biasing unit applies a biasing force to a holder on the plane that is parallel to the direction of the biasing force and includes the pickup roller, and thus a structure of the sheet conveying device can be simplified. Since the sheet conveying device has a simple structure, the sheet conveying device is advantageous in terms of size reduction and space-saving. In addition, according to at least one embodiment described above, the biasing unit applies the biasing force to the holder at the position of overlapping the pickup roller when viewed from the direction of the biasing force, and thus the structure of the sheet conveying device can be simplified. Since the sheet conveying device has a simple structure, the sheet conveying device is advantageous in terms of size reduction and space-saving. 
     While certain embodiments have been described, the embodiments have been presented by way of examples only, and are not intended to limit the scope of the disclosure. These embodiments can be implemented in other various forms, and various omissions, replacements, and changes can be made without departing from the spirit of the disclosure. These embodiments and modifications thereof fall within the scope and spirit of the invention and are included in the scope of the invention recited in the claims and the equivalent thereof.