Patent ID: 12189321

FIRST EMBODIMENT

Next, a first embodiment of the present disclosure will be described in detail with reference to the drawings as appropriate.

As shown inFIG.1, an image forming apparatus1is a color printer. The image forming apparatus1includes a main housing10, a cover11, a supply section20, an image forming section30, and a discharge section90.

The main housing10has an opening10A. The cover11opens and closes the opening10A.

The supply section20is located at a lower portion inside the main housing10. The supply section20includes a sheet tray21that stores sheets S, and a first supply mechanism22that supplies the sheets S from the sheet tray21to the image forming section30. The sheet tray21is configured to be detachable by pulling the same out from the main housing10. The first supply mechanism22includes a first pickup roller23, a first separation roller24, a first separation pad25, and a registration roller26. The sheet S is a medium on which the image forming apparatus1forms an image, and includes plain paper, envelopes, postcards, thin paper, thick paper, glossy paper, resin sheets, stickers, and so on.

In the supply section20, after the sheets S in the sheet tray21are sent out by the first pickup roller23, the sheets S are separated one sheet at a time between the first separation roller24and the first separation pad25. After that, the leading edge position of the sheet S is regulated by the registration roller26in a state where its rotation is stopped, and then the registration roller26is rotated to supply the sheet S to the image forming section30.

The image forming section30has a function of forming an image on the sheet S. The image forming section30includes a scanner unit40, a drawer50, a transfer unit70, and a fixing unit80.

The scanner unit40is provided in an upper portion of the main housing10, and includes a laser emitting section, a polygon mirror, a lens, a reflecting mirror, and so on, which are not shown. The scanner unit40exposes the surface of each photosensitive drum51of the drawer50with a laser beam.

The drawer50is movable between an accommodated position shown inFIG.1and a pulled-out position shown inFIG.2through the opening10A. The drawer50includes four photosensitive drums51and four development cartridges52.

Each photosensitive drum51is attached to the drawer50. Although not shown, in addition to the photosensitive drums51, chargers and so on are attached to the drawer50.

Each development cartridge52is attachable to and detachable from the drawer50. The development cartridge52includes a development roller53that supplies toner to the photosensitive drum51. The development cartridge52contains toner therein.

The transfer unit70is located between the supply section20and the drawer50. The transfer unit70includes a drive roller71, a follow roller72, a conveyance belt73, and transfer rollers74.

The drive roller71and the follow roller72are rollers for rotating the conveyance belt73. The conveyance belt73has an outer surface in contact with the photosensitive drum51. Four transfer rollers74are arranged inside the conveyance belt73to sandwich the conveyance belt73between the transfer rollers74and the photosensitive drums51.

The fixing unit80includes a heat roller81and a pressure roller82. The pressure roller82sandwiches the sheet S with the heat roller81.

In the image forming section30, first, the surface of the photosensitive drum51is uniformly charged by the charger and then exposed by the scanner unit40. Thereby, an electrostatic latent image is formed on the photosensitive drum51. After that, the development roller53supplies toner to the electrostatic latent image on the photosensitive drum51. Thereby, a toner image is formed on the photosensitive drum51.

Next, the sheet S supplied onto the conveyance belt73passes between the photosensitive drum51and the transfer roller74, thereby the toner image on the photosensitive drum51is transferred onto the sheet S. Then, the sheet S passes between the heat roller81and the pressure roller82, thereby the toner image is thermally fixed on the sheet S.

The discharge section90discharges the sheet S on which an image is formed. The discharge section90includes a plurality of conveyance rollers91that convey the sheet S. The sheet S on which the toner image is thermally fixed is conveyed by the conveyance rollers91and discharged to the outside of the main housing10.

As shown inFIG.4A, the image forming apparatus1further includes a sheet conveyance device100and a controller CT. The sheet conveyance device100includes a manual feed tray101, a pressure plate102, a second supply mechanism110, a roller drive mechanism120, and a pressure plate drive mechanism130.

As shown inFIG.3, the manual feed tray101is a tray on which sheets S are set. The manual feed tray101is located on a side surface of the main housing10. The manual feed tray101is rotatably attached to the cover11. The manual feed tray101is rotatable between a closed position shown inFIG.1and an open position shown inFIG.3.

As shown inFIG.3, the cover11has an opening11A through which the sheet S passes. The manual feed tray101closes the opening11A when located at the closed position. The manual feed tray101opens the opening11A when located at the open position.

The pressure plate102is movable between a contact position indicated by a solid line inFIG.3and a separated position indicated by a two-dot chain line. Specifically, the pressure plate102is rotatable with respect to the manual feed tray101, and is rotatable between the contact position and the separated position. Here, the contact position changes depending on the number of sheets S on the pressure plate102.

When the pressure plate102is located at the contact position, the pressure plate102causes the sheet S on the manual feed tray101to contact a second pickup roller111described later. When the pressure plate102is located at the separated position, the pressure plate102causes the sheet S on the manual feed tray101to separate from the second pickup roller111.

The second supply mechanism110includes the second pickup roller111as an example of a supply roller, a second separation roller112, a second separation pad113, a holder114, and a spring115.

The second pickup roller111is a roller for conveying the sheet S on the manual feed tray101. The second pickup roller111is located below the opening10A of the main housing10.

The second separation roller112and the second separation pad113have the function of separating the sheets S sent from the second pickup roller111one sheet at a time. The second separation roller112conveys the sheet S toward the registration roller26.

The second pickup roller111and the second separation roller112are rotatably attached to the holder114. The holder114is rotatably attached to the main housing10. The holder114rotates (pivots) about the rotation axis of the second separation roller112, for example.

The spring115is located between the main housing10and the holder114. The spring115urges the second pickup roller111toward the pressure plate102.

As shown inFIG.4A, the roller drive mechanism120is a mechanism for driving the second pickup roller111. The roller drive mechanism120includes a first motor M1and a first electromagnetic clutch C1.

The first electromagnetic clutch C1is an electromagnetic clutch that allows or cuts off transmission of drive force from the first motor M1to the second pickup roller111. The first motor M1and the first electromagnetic clutch C1are connected directly or indirectly via a particular number of gears.

The second pickup roller111has a gear (not shown) at its axial end. The gear at the end of the second pickup roller111and the first electromagnetic clutch C1are connected directly or indirectly via a particular number of gears. Here, the axial direction is the same direction as the width direction of the sheet S.

The second separation roller112has a gear (not shown) at its axial end. The gear at the end of the second separation roller112and the gear at the end of the second pickup roller111are connected via a particular number of gears.

The pressure plate drive mechanism130is a mechanism for driving the pressure plate102. The pressure plate drive mechanism130includes a second motor M2, a second electromagnetic clutch C2, an input gear131, a planetary gear mechanism140, a torque limiter132, and a push-up member150.

The second electromagnetic clutch C2is an electromagnetic clutch that allows or cuts off transmission of drive force from the second motor M2to the input gear131. The second motor M2and the second electromagnetic clutch C2are connected directly or indirectly via a particular number of gears. The second electromagnetic clutch C2and the input gear131are connected directly or indirectly via a particular number of gears.

As shown inFIG.4B, the planetary gear mechanism140includes a sun gear141, a plurality of planetary gears142, a planetary carrier143, and an outer gear144. The planetary gear mechanism140has a structure in which when rotation of one of the three components of the sun gear141, the planetary carrier143, and the outer gear144is stopped, the remaining components rotate in an interlocking manner.

The sun gear141is a two-stage gear. The sun gear141includes a large-diameter gear portion141A and a small-diameter gear portion141B having a smaller diameter than the large-diameter gear portion141A.

The plurality of planetary gears142are arranged around the small-diameter gear portion141B and engage with the small-diameter gear portion141B. The plurality of planetary gears142are rotatably attached to the planetary carrier143.

The planetary carrier143is rotatable about the rotation axis of the sun gear141. The planetary carrier143has gear teeth143A on its outer circumferential surface.

The outer gear144is a ring-shaped member. The outer gear144has internal teeth144A located on the inner circumferential surface and external teeth144B located on the outer circumferential surface. The internal teeth144A engage with the planetary gears142.

As shown inFIG.4C, the input gear131engages with the gear teeth143A of the planetary carrier143. The torque limiter132engages with the external teeth144B of the outer gear144. Gear teeth152A described later of the push-up member150engage with the large-diameter gear portion141A of the sun gear141.

That is, the input gear131is connected to the planetary carrier143as an example of a first component. The torque limiter132is connected to the outer gear144as an example of a second component. The push-up member150is connected to the sun gear141as an example of a third component. Note that connection (“connected to”) includes direct connection as well as indirect connection via a particular number of gears.

The torque limiter132is rotatable when a torque greater than or equal to a threshold value is applied. When the torque applied from the outer gear144is less than the threshold value, the torque limiter132does not rotate to restrict the rotation of the outer gear144. The threshold value of the torque limiter132is set to a value corresponding to the force pressing the pressure plate102against the second pickup roller111. The torque limiter132functions as a torque limiter in both forward and reverse directions.

The push-up member150is a member that pushes up the pressure plate102from the separated position to the contact position. The push-up member150is rotatable about a first axis X1 between a push-up position indicated by a solid line and a retracted position indicated by a two-dot chain line. The push-up position is the position of the push-up member150when the pressure plate102is located at the contact position. The retracted position is the position of the push-up member150when the pressure plate102is located at the separated position. When located at the retracted position, the push-up member150is positioned by contacting a portion of the main housing10.

The push-up member150includes a first portion151extending from the first axis X1 toward the pressure plate102and a second portion152having a fan shape whose center is the first axis X1.

The first portion151has a contact portion151A that contacts the pressure plate102when the pressure plate102is located at the contact position. As shown inFIG.5, the contact portion151A of the push-up member150is located within the range of the second pickup roller111in the width direction of the sheet S. Specifically, in the width direction of the sheet S, the center of the second pickup roller111is located within the range of the contact portion151A. More specifically, in the width direction of the sheet S, the center of the second pickup roller111is located at the same position as the center of the contact portion151A. In the present embodiment, the second pickup roller111is located at the center in the width direction with respect to the sheet S on the manual feed tray101.

As shown inFIG.4A, the second portion152extends from the first axis X1 toward the opposite side of the first portion151so as to gradually widen. As shown inFIG.4C, the second portion152has gear teeth152A on its outer circumferential surface. The gear teeth152A engage with the large-diameter gear portion141A of the sun gear141.

With the configuration described above, the drive force transmitted from the input gear131to the planetary gear mechanism140is output to either the torque limiter132or the push-up member150. Specifically, in a case where a drive force is input to the input gear131to rotate the input gear131in the direction indicated by the arrow in the figure (hereinafter also referred to as “first rotation direction”) when the pressure plate102is located at the separated position, the rotation of the outer gear144is stopped by the torque limiter132and thus the sun gear141rotates in conjunction with the planetary carrier143. Thereby, the push-up member150is rotated from the retracted position to the push-up position by the drive force input from the input gear131, and thus the pressure plate102moves from the separated position to the contact position.

When the pressure plate102reaches the contact position, the rotation of the push-up member150is stopped. This stops the rotation of the sun gear141connected to the push-up member150, and thus the outer gear144rotates in conjunction with the planetary carrier143that rotates by being connected to the input gear131, and the torque limiter132is rotated by the drive force input from the input gear131.

In a case where a drive force is input to the input gear131in a second rotation direction opposite to the first rotation direction when the pressure plate102is located at the contact position, rotation of the outer gear144is stopped by the torque limiter132and the sun gear141rotates in conjunction with the planetary carrier143. Since the push-up member150rotates from the push-up position to the retracted position by the drive force input from the input gear131, the pressure plate102moves from the contact position to the separated position.

When the push-up member150reaches the retracted position, the push-up member150contacts the main housing10, and the rotation of the push-up member150is stopped. Since this stops the rotation of the sun gear141connected to the push-up member150, the outer gear144rotates in conjunction with the planetary carrier143that rotates by being connected to the input gear131, and the torque limiter132is rotated by the drive force input from the input gear131.

The controller CT includes a CPU, a ROM, a RAM, a non-volatile memory, and so on, and is configured to perform various controls based on programs prepared in advance. When printing a plurality of sheets S, the controller CT has a function of conveying a plurality of sheets S by moving the pressure plate102from the separated position to the contact position and then intermittently driving the second pickup roller111without moving the pressure plate102from the contact position. Specifically, as the number of sheets S stacked on the pressure plate102decreases, the pressure plate102relatively rises.

Specifically, in response to receiving a print instruction for printing a plurality of sheets S, the controller CT rotates the second motor M2in the forward direction, supplies current to the second electromagnetic clutch C2to be in the transmission state to transmit the drive force of the second motor M2to the input gear131, thereby rotating the input gear131in the first rotation direction. This causes the pressure plate102to move from the separated position to the contact position, as described above.

After the pressure plate102has moved to the contact position, the controller CT stops the second motor M2and stops the supply of current to the second electromagnetic clutch C2to be in the cut-off state. Thereby, the pressure plate102is maintained at the contact position.

After that, the controller CT drives the first motor M1and controls the first electromagnetic clutch C1according to the number of sheets S, thereby intermittently driving the second pickup roller111. Since the second pickup roller111is intermittently driven in a state where the pressure plate102is maintained at the contact position, a plurality of sheets S are conveyed without moving the pressure plate102from the contact position.

In a case where the drive force of the first motor M1is used for other components such as the photosensitive drum51, the driving timing of the first motor M1may be before the timing at which the second pickup roller111is first rotated for the first sheet S. In this case, the second pickup roller111may be first rotated for the first sheet S by controlling only the first electromagnetic clutch C1.

After printing is completed, the controller CT performs processing for returning the pressure plate102from the contact position to the separated position. More specifically, the controller CT reversely rotates the second motor M2and applies a current to the second electromagnetic clutch C2to be in the transmission state, thereby transmitting the drive force of the second motor M2to the input gear131so that the input gear131is rotated in the second rotation direction. Thereby, the pressure plate102moves from the contact position to the separated position, as described above.

After the pressure plate102has moved to the separated position, the controller CT stops the second motor M2and stops the supply of current to the second electromagnetic clutch C2to be in the cut-off state. Thereby, the pressure plate102is maintained at the separated position.

As described above, according to the first embodiment, the following effects are obtained.

When printing a plurality of sheets S, the second pickup roller111is intermittently driven without moving the pressure plate102from the contact position. This suppresses the generation of noise due to movement of the pressure plate102when printing a plurality of sheets S.

As shown inFIG.5, in the width direction of the sheet S, the contact portion151A of the push-up member150is located within the range of the second pickup roller111. Thus, when the pressure plate102is pushed up to the contact position by the push-up member150, bending (deflection) of the pressure plate102with the second pickup roller111as a fixed point is suppressed.

Second Embodiment

Next, a second embodiment of the present disclosure will be described in detail with reference to the drawings as appropriate. Since the present embodiment partially modifies the structure of the pressure plate drive mechanism130according to the first embodiment described above, the same reference numerals are given to components that are substantially the same as those of the first embodiment and descriptions thereof are omitted.

As shown inFIG.6, a pressure plate drive mechanism230according to the second embodiment includes a pendulum gear260instead of the second electromagnetic clutch C2of the pressure plate drive mechanism130according to the first embodiment. The pendulum gear260is rotatable around the input gear131while engaging with the input gear131. The pendulum gear260is rotatable between a transmission position indicated by a solid line inFIG.6and a cutoff position indicated by a two-dot chain line.

When the pendulum gear260is located at the transmission position, the pendulum gear260transmits drive force from the second motor M2to the planetary carrier143. Specifically, when the pendulum gear260is located at the transmission position, the pendulum gear260engages with the planetary carrier143.

When the pendulum gear260is located at the cutoff position, the pendulum gear260cuts off the drive force from the second motor M2to the planetary carrier143. Specifically, when the pendulum gear260is located at the cutoff position, the pendulum gear260is separated from the planetary carrier143.

The pendulum gear260is configured to be switched between the transmission position and the cutoff position by a solenoid actuator (not shown) and so on. When transmitting the drive force of the second motor M2to the planetary carrier143, the controller CT controls the pendulum gear260to rotate from the cutoff position to the transmission position.

The pendulum gear260may move from the cutoff position to the transmission position when the second motor M2rotates in the forward direction, and may move from the transmission position to the cutoff position when the second motor M2rotates in the reverse direction. In this case, rotation of the second motor M2in the reverse direction may disconnect the pendulum gear260from the planetary carrier143, and the planetary carrier143may idly rotate due to the force by own weight of the pressure plate102, and the pressure plate102may move from the contact position to the separated position by its own weight.

As described above, also in the second embodiment, by controlling the position of the pendulum gear260by the controller CT, the pressure plate102is moved up and down in the same manner as in the first embodiment. Alternatively, the pendulum gear may be movable linearly.

Third Embodiment

Next, a third embodiment of the present disclosure will be described in detail with reference to the drawings as appropriate. Since this embodiment is obtained by modifying the structure of the pressure plate drive mechanism130according to the first embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and descriptions thereof are omitted.

As shown inFIG.7, a pressure plate drive mechanism330according to the third embodiment includes the second motor M2and the input gear131substantially same as those of the first embodiment, and a sector gear340, a cam350, a spring360, a sector lever370, and a push-up member380different from the first embodiment.

The sector gear340has a first tooth portion341, a second tooth portion342, a first toothless portion343, and a second toothless portion344on the outer circumferential surface. The first tooth portion341and the second tooth portion342are portions that are engageable with the input gear131. The first toothless portion343and the second toothless portion344are portions that are not engageable with the input gear131. The first tooth portion341, the second tooth portion342, the first toothless portion343, and the second toothless portion344are arranged on the outer circumferential surface of the sector gear340in the order of the first toothless portion343, the first tooth portion341, the second toothless portion344, and the second tooth portion342.

Specifically, toward the upstream side in the rotation direction of the sector gear340(seeFIG.8), the first toothless portion343, the first tooth portion341, the second toothless portion344, and the second tooth portion342are arranged in this order. Here, the rotation direction of the sector gear340is the rotation direction of the sector gear340when the sector gear340receives the drive force from the input gear131, and is the clockwise direction in the figure.

The first toothless portion343is located upstream of the second tooth portion342in the rotation direction of the sector gear340. The first tooth portion341is located upstream of the first toothless portion343in the rotation direction of the sector gear340. The second toothless portion344is located upstream of the first tooth portion341in the rotation direction of the sector gear340. The second tooth portion342is located upstream of the second toothless portion344in the rotation direction of the sector gear340.

The sector gear340has a first protrusion345, a second protrusion346, a spring contact portion347, and a cam350. The first protrusion345and the second protrusion346are protrusions with which the sector lever370engages. The spring contact portion347is a portion with which the spring360makes contact.

When the sector lever370engages with the first protrusion345, the first toothless portion343faces the input gear131and no drive force is transmitted from the input gear131to the sector gear340. As shown inFIG.9, when the sector lever370engages with the second protrusion346, the second toothless portion344faces the input gear131and no drive force is transmitted from the input gear131to the sector gear340.

The cam350is a cam that moves the push-up member380. The cam350is fixed or integrally formed with the sector gear340. The cam350rotates together with the sector gear340. The cam350is alternately switchable between a first cam position shown inFIG.7and a second cam position shown inFIG.9.

The push-up member380is rotatable about the first axis X1 between a push-up position indicated by a solid line in the figure and a retracted position indicated by a two-dot chain line. The push-up position is the position of the push-up member380when the pressure plate102is located at the contact position. The retracted position is the position of the push-up member380when the pressure plate102is located at the separated position. When the push-up member380is located at the retracted position, the push-up member380is positioned by contacting a portion of the main housing10. The push-up member380is urged from the push-up position toward the retracted position by a spring (not shown).

The push-up member380has a first portion381substantially same as the first portion151of the first embodiment and a second portion382different from the first embodiment. A contact portion381A of the first portion381for contacting the pressure plate102is located within the range of the second pickup roller111in the width direction of the sheet S. The second portion382extends from the first axis X1 toward the cam350located at the first cam position.

When the cam350is located at the first cam position, the cam350contacts the second portion382to hold the push-up member380at the push-up position. When the cam350rotates from the first cam position to the second cam position, the cam350separates from the second portion382and the push-up member380rotates from the push-up position to the retracted position by a spring (not shown).

The spring360urges the sector gear340in the rotation direction of the sector gear340. The spring360urges the spring contact portion347in the rotation direction regardless of whether the cam350is located at the first cam position or the second cam position.

The sector lever370is rotatable between a rotation restricting position shown inFIG.7and a rotation allowing position shown inFIG.8. The sector lever370is configured to engage with the first protrusion345or the second protrusion346of the sector gear340when the sector lever370is located at the rotation restricting position. By engaging with the first protrusion345or the second protrusion346, the sector lever370stops the rotation of the sector gear340due to the urging force of the spring360.

As shown inFIG.8, the sector lever370separates from the first protrusion345or the second protrusion346of the sector gear340when the sector lever370is located at the rotation allowing position. By separating from the first protrusion345or the second protrusion346, the sector lever370allows rotation of the sector gear340due to the urging force of the spring360.

The sector lever370is switchable between the rotation restricting position and the rotation allowing position by a spring371and a solenoid actuator372. The spring371urges the sector lever370from the rotation allowing position toward the rotation restricting position. The solenoid actuator372includes a piston372A that engages with the sector lever370. The piston372A is movable between an advanced position shown inFIG.7and a retracted position shown inFIG.8.

As shown inFIG.7, in a state where the sector lever370is located at the rotation restricting position and engages with the first protrusion345, the first toothless portion343faces the input gear131and the pressure plate102is located at the contact position. As shown inFIG.9, in a state where the sector lever370is located at the rotation restricting position and engages with the second protrusion346, the second toothless portion344faces the input gear131and the pressure plate102is located at the separated position.

As shown inFIG.7, when rotating the pressure plate102from the contact position to the separated position, the controller CT drives the second motor M2in one direction and moves the piston372A of the solenoid actuator372from the advanced position to the retracted position. Then, as shown inFIG.8, the sector lever370moves to the rotation allowing position and separates from the first protrusion345. When the sector lever370separates from the first protrusion345, the sector gear340rotates due to the urging force of the spring360and the first tooth portion341of the sector gear340engages with the input gear131.

When the first tooth portion341engages with the input gear131, the sector gear340rotates and the cam350rotates in a direction away from the push-up member380. Thereby, the push-up member380is rotated from the push-up position toward the retracted position by a spring (not shown), and the pressure plate102supported by the push-up member380rotates from the contact position toward the separated position.

Before the cam350reaches the second cam position shown inFIG.9, the controller CT switches the piston372A of the solenoid actuator372from the retracted position to the advanced position, so that the sector lever370is located at the rotation restricting position. As shown inFIG.9, when the cam350reaches the second cam position, the sector lever370engages with the second protrusion346of the sector gear340and the sector gear340stops.

Further, when the cam350reaches the second cam position, since the push-up member380rotates to the retracted position, the pressure plate102moves to the separated position. That is, when rotating the pressure plate102from the contact position to the separated position, the drive force input to the input gear131rotates the cam350from the first cam position to the second cam position via the sector gear340, and thus the push-up member380causes the pressure plate102to move from the contact position to the separated position.

As shown inFIG.9, when rotating the pressure plate102from the separated position to the contact position, the controller CT drives the second motor M2in one direction and switches the piston372A of the solenoid actuator372from the advanced position to the retracted position. That is, in the third embodiment, the second motor M2is rotated in the same direction without switching the rotation direction of the second motor M2, both when the pressure plate102is lowered and when the pressure plate102is raised.

When the piston372A is switched from the advanced position to the retracted position, as shown inFIG.10, the sector lever370moves to the rotation allowing position and separates from the second protrusion346. When the sector lever370separates from the second protrusion346, the sector gear340rotates due to the urging force of the spring360and the second tooth portion342of the sector gear340engages with the input gear131.

When the second tooth portion342engages with the input gear131, the sector gear340rotates and the cam350rotates in a direction approaching the push-up member380. Thereby, since the cam350pushes the push-up member380against the urging force of the spring (not shown), the push-up member380rotates from the retracted position toward the push-up position, and the pressure plate102supported by the push-up member380rotates from the separated position toward the contact position.

Before the cam350reaches the first cam position shown inFIG.7, the controller CT switches the piston372A of the solenoid actuator372from the retracted position to the advanced position, so that the sector lever370is located at the rotation restricting position. Thereby, as shown inFIG.7, when the cam350reaches the first cam position, the sector lever370engages with the first protrusion345of the sector gear340and the sector gear340stops.

When the cam350reaches the first cam position, the push-up member380rotates to the push-up position, and thus the pressure plate102moves to the contact position. That is, when rotating the pressure plate102from the separated position to the contact position, the drive force input to the input gear131rotates the cam350from the second cam position to the first cam position via the sector gear340, and thus the push-up member380causes the pressure plate102to move from the separated position to the contact position.

As described above, since the pressure plate102is maintained at the contact position also in the third embodiment, the same effects as in the first embodiment are obtained.

Fourth Embodiment

Next, a fourth embodiment of the present disclosure will be described in detail with reference to the drawings as appropriate. Since this embodiment differs from the first embodiment described above in the structure of the sheet conveyance device, components that are substantially the same as those of the first embodiment are denoted by the same reference numerals, and descriptions thereof are omitted.

As shown inFIGS.11and13, a sheet conveyance device400according to the fourth embodiment includes a motor M3, a drive gear Gd, a transmission switching mechanism410, a pressure plate operating mechanism420, and a switching mechanism430. In the sheet conveyance device400according to the fourth embodiment, the drive force of one motor M3is used to drive the second pickup roller111and to rotate a push-up member480described later.

Specifically, the controller CT according to the fourth embodiment rotates the motor M3forward when conveying the sheet S or when raising the pressure plate102. The motor M3is a stepping motor. The controller CT rotates the motor M3reversely by a particular amount when lowering the pressure plate102.

The drive gear Gd is connected to the motor M3directly or indirectly via a particular number of gears. As shown inFIG.13, the drive gear Gd engages with a sun gear441of the transmission switching mechanism410described later, and also engages with a transmission gear Gt of the pressure plate operating mechanism420described later.

As shown inFIGS.11and13, the transmission switching mechanism410is a mechanism configured to switch between a transmission state in which the drive force of the motor M3is transmitted to the second pickup roller111and a non-transmission state in which the drive force of the motor M3is not transmitted to the second pickup roller111. The transmission switching mechanism410includes a planetary gear mechanism440, a transmission switching lever L1, and a solenoid actuator SA.

As shown inFIGS.13and16, the planetary gear mechanism440includes a sun gear441, a plurality of planetary gears442, a planetary carrier443, and an outer gear444. The planetary gear mechanism440has a structure in which when rotation of one of the three components of the sun gear441, the planetary carrier443, and the outer gear444is stopped, the remaining components rotate in an interlocking manner.

The sun gear441is a two-stage gear. The sun gear441includes a large-diameter gear portion441A shown inFIG.13and a small-diameter gear portion441B shown inFIG.16. The small-diameter gear portion441B has a smaller diameter than the large-diameter gear portion441A.

The plurality of planetary gears442are arranged around the small-diameter gear portion441B and engage with the small-diameter gear portion441B. The plurality of planetary gears442are rotatably attached to the planetary carrier443.

As shown inFIG.13, the planetary carrier443is rotatable about the rotation axis of the sun gear441. The planetary carrier443has a plurality of pawls443A on the outer circumferential surface.

As shown inFIG.16, the outer gear444is a ring-shaped member. The outer gear444has internal teeth444A located on the inner circumferential surface and external teeth444B located on the outer circumferential surface. The internal teeth444A engage with the planetary gear442.

As shown inFIG.13, the drive gear Gd engages with the large-diameter gear portion441A of the sun gear441. The external teeth444B of the outer gear444engage with the roller gear Gr. As shown inFIG.11, the roller gear Gr is attached to one end of a shaft SF that supports the second separation roller112. The drive force transmitted to the shaft SF is also transmitted to the second pickup roller111via a gear (not shown).

In a state where rotation of the planetary carrier443is stopped, the drive force from the drive gear Gd is transmitted to the second separation roller112and the second pickup roller111via the planetary gear mechanism440. In a state where rotation of the planetary carrier443is allowed, the roller gear Gr and so on act as resistance to the rotation of the outer gear444and stop the rotation of the outer gear444, thereby the drive force from the drive gear Gd is transmitted to the planetary carrier443and the planetary carrier443rotates idly. That is, in a state where rotation of the planetary carrier443is allowed, the drive force from the drive gear Gd is not transmitted to the second pickup roller111, and the second pickup roller111does not rotate.

The transmission switching lever L1is a lever for stopping or allowing rotation of the planetary carrier443. The transmission switching lever L1is rotatable between a transmission position shown inFIG.21and a non-transmission position shown inFIG.14. When the transmission switching lever L1is located at the transmission position, the transmission switching lever L1engages with a pawl443A of the planetary carrier443to stop rotation of the planetary carrier443. In this way, when the transmission switching lever L1is located at the transmission position, the transmission switching mechanism410is in the transmission state.

When the transmission switching lever L1is located at the non-transmission position, the transmission switching lever L1disengages from the pawl443A of the planetary carrier443, thereby allowing rotation of the planetary carrier443. In this way, when the transmission switching lever L1is located at the non-transmission position, the transmission switching mechanism410is in the non-transmission state.

The solenoid actuator SA is an actuator for moving the transmission switching lever L1between the transmission position and the non-transmission position. As shown inFIG.15, the solenoid actuator SA includes a piston SA1engaging with the transmission switching lever L1. The piston SA1is movable between an advanced position shown inFIG.15and a retracted position shown inFIG.21. The tip of the piston SA1engages with the transmission switching lever L1.

The transmission switching lever L1is urged from the transmission position toward the non-transmission position by a spring (not shown). When the piston SA1is moved from the advanced position to the retracted position, the transmission switching lever L1rotates from the non-transmission position to the transmission position against the urging force of the spring. When the piston SA1is moved from the retracted position to the advanced position, the transmission switching lever L1rotates from the transmission position to the non-transmission position by the urging force of the spring.

As shown inFIG.11, the pressure plate operating mechanism420is switchable between an operating state in which the pressure plate102is operated by using the drive force of the motor M3and a non-operating state in which the drive force of the motor M3is cut off and the pressure plate102is not operated. The pressure plate operating mechanism420includes a push-up mechanism421for pushing up the pressure plate102and an operating mechanism422for operating the push-up mechanism421.

The push-up mechanism421includes a push-up member480, a drive shaft450for moving the push-up member480, and a pressure plate spring SP1.

The push-up member480is rotatable between a retracted position shown inFIG.11and a push-up position shown inFIG.12. The push-up member480has a contact portion481that contacts the pressure plate102and a gear portion482. The contact portion481is located within the range of the second pickup roller111in the width direction of the sheet S.

The drive shaft450extends in the width direction of the sheet S. The drive shaft450has a gear portion451in the center in the width direction. The gear portion451engages with the gear portion482of the push-up member480(see alsoFIG.20). The drive shaft450has a cam contact portion452at its one end. The cam contact portion452configured to contact a cam CM of the operating mechanism422described later. The cam contact portion452is rotatable between a separated-state position shown inFIG.11and a contact-state position shown inFIG.12.

When the cam contact portion452rotates from the separated-state position to the contact-state position, the drive shaft450rotates clockwise in the figure, and the push-up member480engaging with the gear portion451rotates from the retracted position to the push-up position. When the cam contact portion452rotates from the contact-state position to the separated-state position, the drive shaft450rotates counterclockwise in the figure, and the push-up member480engaging with the gear portion451rotates from the push-up position to the retracted position.

The pressure plate spring SP1is connected to the other end of the drive shaft450. The pressure plate spring SP1urges the drive shaft450clockwise in the figure. Thus, the pressure plate spring SP1urges the pressure plate102from the separated position toward the contact position via the drive shaft450and the push-up member480.

As shown inFIG.13, the operating mechanism422includes a transmission gear Gt, an input gear G1, a sector gear Gs, a spring SP2, a spring holder H holding the spring SP2, the cam CM, an output gear G2, and two idle gears G3and G4.

The transmission gear Gt engages with the drive gear Gd. The input gear G1is a gear to which drive force is input from the drive gear Gd via the transmission gear Gt. The input gear G1includes a first gear G11and a second gear G12.

The first gear G11engages with the transmission gear Gt. A drive force is input to the first gear G11from the transmission gear Gt.

The second gear G12is a gear with a larger diameter than the first gear G11. The second gear G12is connected to the first gear G11via a second one-way clutch C4shown inFIG.18.

The second one-way clutch C4has a function of connecting the first gear G11and the second gear G12such that the first gear G11rotates together with the second gear G12when raising the pressure plate102. The second one-way clutch C4has a function of disconnecting the first gear G11and the second gear G12such that the first gear G11rotates relative to the second gear G12when lowering the pressure plate102.

As shown inFIG.17, the sector gear Gs has a first tooth portion Gs1, a second tooth portion Gs2, a first toothless portion Gs3, and a second toothless portion Gs4on the outer circumferential surface. The first tooth portion Gs1and the second tooth portion Gs2are portions that are engageable with the second gear G12of the input gear G1. The first toothless portion Gs3and the second toothless portion Gs4are portions that are not engageable with the second gear G12of the input gear G1.

The first tooth portion Gs1, the second tooth portion Gs2, the first toothless portion Gs3and the second toothless portion Gs4are arranged on the outer circumferential surface of the sector gear Gs in the order of the first toothless portion Gs3, the first tooth portion Gs1, the second toothless portion Gs4, and the second tooth portion Gs2. Specifically, toward the upstream side in the rotation direction of the sector gear Gs (seeFIG.22) when the pressure plate102is raised, the first toothless portion Gs3, the first tooth portion Gs1, the second toothless portion Gs4, and the second tooth portion Gs2are arranged in this order.

The sector gear Gs is rotatable between a first sector position shown inFIG.17and a second sector position shown inFIG.25A. When the sector gear Gs is located at the first sector position, the first toothless portion Gs3faces the second gear G12. When the sector gear Gs is located at the second sector position, the second toothless portion Gs4faces the second gear G12.

When the first toothless portion Gs3or the second toothless portion Gs4faces the second gear G12, the state of the pressure plate operating mechanism420is the non-operating state. When the first tooth portion Gs1engages with the second gear G12, the state of the pressure plate operating mechanism420is the operating state.

When the pressure plate102is raised, the sector gear Gs rotates clockwise in the figure from the first sector position to the second sector position. When the pressure plate102is lowered, the sector gear Gs rotates counterclockwise in the figure from the second sector position to the first sector position.

As shown inFIG.15, the sector gear Gs further includes a protrusion Gs5and a holding portion Gs6. The protrusion Gs5is configured to, when the sector gear Gs is located at the first sector position, engage with a sector lever L2(described later) in the rotation direction of the sector gear Gs.

The holding portion Gs6is configured to, when the sector gear Gs is located at the second sector position, engage with the sector lever L2in the rotation direction of the sector gear Gs. The holding portion Gs6has a recess into which the tip of the sector lever L2is inserted. With this configuration, the holding portion Gs6is engageable with the sector lever L2in the rotation direction of the sector lever L2as well.

The spring SP2urges the sector gear Gs in the rotation direction of the sector gear Gs when raising the pressure plate102. That is, the spring SP2urges the sector gear Gs clockwise in the figure (FIG.15, for example). As shown inFIG.13, the spring SP2is located between the sector gear Gs and the spring holder H.

The spring holder H holds the spring SP2. The spring holder H is rotatable relative to the sector gear Gs within a particular angular range. The rotation center of the spring holder H and the rotation center of the sector gear Gs are the same. The diameter of the spring holder H is the same as the diameter of the sector gear Gs.

The spring holder H has a portion that engages with a part of the sector gear Gs in the rotation direction of the sector gear Gs. When the sector gear Gs rotates relative to the spring holder H by a particular angle, the part of the sector gear Gs engages with a part of the spring holder H, and the sector gear Gs and the spring holder H rotate together.

The spring holder H has a first tooth portion H1, a second tooth portion H2, a first toothless portion H3, and a second toothless portion H4on the outer circumferential surface. The first tooth portion H1and the second tooth portion H2are portions that are engageable with the second gear G12of the input gear G1. The first toothless portion H3and the second toothless portion H4are portions that are not engageable with the second gear G12of the input gear G1.

When viewed from the axial direction of the sector gear Gs, the first tooth portion H1has a shape that matches the first tooth portion Gs1. When viewed from the axial direction, the second tooth portion H2has a shape that matches the second tooth portion Gs2. When viewed from the axial direction, the first toothless portion H3has a shape that matches the shape of the first toothless portion Gs3. When viewed from the axial direction, the second toothless portion H4has a shape that matches the shape of the second toothless portion Gs4.

The cam CM is formed integrally with the spring holder H. Thus, the cam CM rotates in conjunction with the sector gear Gs.

The cam CM is rotatable between a separation corresponding position shown inFIG.11and a contact corresponding position shown inFIG.12. The rotation center of the cam CM and the rotation center of the spring holder H are the same. When the cam CM is located at the separation corresponding position, the cam CM causes the pressure plate102to be located at the separated position. When the cam CM is located at the contact corresponding position, the cam CM causes the pressure plate102to be located at the contact position.

As shown inFIGS.11and13, the outer peripheral surface of the cam CM has a distal end portion CM1farthest from the center of rotation of the cam CM. The distal end portion CM1has a concave portion CM11recessed toward the rotation center of the cam CM. When the cam CM is located at the separation corresponding position, the distal end portion CM1of the cam CM contacts the cam contact portion452. Specifically, when the cam CM is located at the separation corresponding position, the cam contact portion452enters the concave portion CM11(seeFIG.11). Thus, the cam contact portion452is located at the separated-state position, the push-up member480is located at the retracted position, and the pressure plate102is located at the separated position.

When the distal end portion CM1of the cam CM contacts the cam contact portion452, the frictional force between the distal end portion CM1of the cam CM and the cam contact portion452is high due to the urging force of the pressure plate spring SP1. This suppresses rotation of the spring holder H due to the urging force of the spring SP2in a state where the cam CM is located at the separation corresponding position.

When the cam CM rotates from the separation corresponding position to the contact corresponding position, the distal end portion CM1of the cam CM separates from the cam contact portion452. Thus, the urging force of the pressure plate spring SP1causes the cam contact portion452to rotate toward the contact-state position, the push-up member480rotates toward the push-up position, and the pressure plate102rotates toward the contact position.

When the cam CM is located at the contact corresponding position, a portion of the outer peripheral surface of the cam CM on the side opposite to the distal end portion CM1contacts the cam contact portion452. Thus, the cam contact portion452is located at the contact-state position, the push-up member480is located at the push-up position, and the pressure plate102is located at the contact position.

Even when the portion of the cam CM opposite to the distal end portion CM1contacts the cam contact portion452, the frictional force between the cam CM and the cam contact portion452is high due to the urging force of the pressure plate spring SP1. Thus, even when the cam CM is located at the contact corresponding position, rotation of the spring holder H due to the urging force of the spring SP2is suppressed.

Note that, when the cam CM is located at the contact corresponding position, the cam contact portion452need not necessarily contact the cam CM. For example, when the cam CM is located at the contact corresponding position, the pressure plate102may be maintained at the contact position due to contact between the gear portion451, the cam contact portion452, or the push-up member480and a part of the main housing10. Further, when the cam CM is located at the contact corresponding position, the pressure plate102may be maintained at the contact position by stopping the movement of the pressure plate102by the second pickup roller111.

When the cam CM rotates from the contact corresponding position to the separation corresponding position, the distal end portion CM1of the cam CM pushes the cam contact portion452toward the separated-state position against the urging force of the pressure plate spring SP1. Thereby, the cam contact portion452rotates toward the separated-state position, the push-up member480rotates toward the retracted position, and the pressure plate102rotates toward the separated position.

As shown inFIG.13, the output gear G2is rotatable about the rotation center of the cam CM. The output gear G2is connected to the first gear G11of the input gear G1via two idle gears G3and G4(see alsoFIG.19). Thereby, the drive force of the motor M3transmitted to the first gear G11is transmitted to the output gear G2via the idle gears G3and G4.

The first gear G11, the idle gears G3and G4, and the output gear G2have the same module, the same pitch diameter, and the same number of teeth. The second gear G12and the sector gear Gs have the same module and the same pitch diameter.

The output gear G2is connected to the cam CM via a first one-way clutch C3shown inFIG.18.

The first one-way clutch C3is a clutch for idly rotating the output gear G2relative to the cam CM when transmitting the drive force of the motor M3to the second pickup roller111in a state where the pressure plate102is located at the contact position. That is, the first one-way clutch C3disconnects the output gear G2and the cam CM such that the output gear G2is rotatable relative to the cam CM when the motor M3is rotating forward. The first one-way clutch C3connects the output gear G2and the cam CM when the motor M3is rotating reversely.

As shown inFIG.15, the switching mechanism430is a mechanism for switching the state of the pressure plate operating mechanism420. The switching mechanism430includes the sector lever L2and a connecting spring SP3.

The sector lever L2is rotatable relative to the transmission switching lever L1. The sector lever L2is rotatable about the same axis as the transmission switching lever L1. The sector lever L2is rotatable between a rotation restricting position shown inFIG.15and a rotation allowing position shown inFIG.21.

When the sector lever L2is located at the rotation restricting position, the sector lever L2stops rotation of the sector gear Gs due to the urging force of the spring SP2by engaging with the protrusion Gs5of the sector gear Gs. When the sector lever L2is located at the rotation allowing position, the sector lever L2allows rotation of the sector gear Gs due to the urging force of the spring SP2by disengaging from the protrusion Gs5of the sector gear Gs.

The sector lever L2is configured to interlock with the transmission switching lever L1. Specifically, the transmission switching lever L1has a protrusion B1. The sector lever L2has a protrusion B2. When the transmission switching lever L1rotates from the transmission position toward the non-transmission position, the protrusion B1pushes the protrusion B2, causing the sector lever L2to rotate from the rotation allowing position to the rotation restricting position.

The connection spring SP3is a torsion spring. The connection spring SP3has a coil portion CL, a first arm portion A1, and a second arm portion A2. The coil portion CL is arranged so as to surround the rotation center of the sector lever L2.

The tip of the first arm portion A1is located at a position where the tip of the first arm portion A1is pushed by the transmission switching lever L1when the transmission switching lever L1rotates from the non-transmission position toward the transmission position. Specifically, the tip of the first arm portion A1engages with the surface of the transmission switching lever L1on the planetary carrier443side.

The second arm portion A2is located at a position where the second arm portion A2pushes the sector lever L2when the transmission switching lever L1rotates from the non-transmission position toward the transmission position. Specifically, the second arm portion A2engages with the protrusion B2. The protrusion B2is located between the protrusion B1and the second arm portion A2. When the transmission switching lever L1rotates from the non-transmission position toward the transmission position, the second arm A2pushes the protrusion B2, causing the sector lever L2to rotate from the rotation restricting position to the rotation allowing position.

As shown inFIG.24, when the sector gear Gs is located at the second sector position, the tip of the sector lever L2is in the holding portion Gs6of the sector gear Gs. Thus, when the pressure plate102is located at the contact position, the sector lever L2engages with the holding portion Gs6so as not to rotate from the rotation restricting position to the rotation allowing position. The transmission switching lever L1is rotatable between the transmission position and the non-transmission position in a state where the sector lever L2engages with the holding portion Gs6.

More specifically, when the transmission switching lever L1rotates from the non-transmission position to the transmission position in a state where the movement of the sector lever L2is stopped by the holding portion Gs6, the transmission switching lever L1moves to the transmission position against the urging force of the connection spring SP3. At this time, the protrusion B1moves away from the protrusion B2. When the transmission switching lever L1rotates from the transmission position to the non-transmission position in a state where the movement of the sector lever L2is stopped by the holding portion Gs6, the transmission switching lever L1is rotatable to the non-transmission position because the protrusion B1is separated from the protrusion B2.

Next, operations of the controller CT and the sheet conveyance device400will be described in detail. The position of each member when printing is not performed is the position shown inFIG.15.

In response to receiving a print instruction for printing a plurality of sheets S, the controller CT controls the motor M3to rotate forward. When the motor M3rotates forward, the drive gear Gd rotates counterclockwise as shown inFIG.15.

When the drive gear Gd rotates, the sun gear441rotates. However, since the transmission switching lever L1is located at the non-transmission position, the drive force of the motor M3is not transmitted to the roller gear Gr. As shown inFIG.19, when the drive gear Gd rotates, the transmission gear Gt, the first gear G11, the idle gears G3and G4and the output gear G2rotate.

When the motor M3rotates forward, no drive force is transmitted from the output gear G2to the cam CM via the first one-way clutch C3, and thus the output gear G2rotates relative to the cam CM in a stopped state. Further, when the motor M3rotates forward, the drive force is transmitted from the first gear G11to the second gear G12via the second one-way clutch C4, and thus the second gear G12rotates as shown inFIG.17. However, since the first toothless portion Gs3of the sector gear Gs faces the second gear G12, the sector gear Gs does not rotate.

Similarly, when the motor M3rotates forward in a state where the second toothless portion Gs4of the sector gear Gs faces the second gear G12, the sector gear Gs does not rotate and the output gear G2rotates relative to the cam CM in a stopped state. That is, when the motor M3rotates forward in a state where the pressure plate102is stopped, the sector gear Gs does not rotate and the output gear G2rotates relative to the cam CM in a stopped state.

After driving the motor M3, the controller CT switches the piston SA1of the solenoid actuator SA from the advanced position to the retracted position. The actuation of the solenoid actuator SA may be started earlier than the start of driving the motor M3, or may be simultaneous with the start of driving the motor M3.

When the solenoid actuator SA is actuated, the transmission switching lever L1rotates from the non-transmission position to the transmission position, and as shown inFIG.21, the tip of the transmission switching lever L1engages with the pawl443A of the planetary carrier443. Thereby, the drive force of the motor M3is transmitted to the roller gear Gr, and the second pickup roller111rotates. At this time, since the pressure plate102is located at the separated position, the sheet S on the pressure plate102is not conveyed.

When the transmission switching lever L1rotates from the non-transmission position to the transmission position, the sector lever L2rotates from the rotation restricting position to the rotation allowing position, and the tip of the sector lever L2separates from the protrusion Gs5of the sector gear Gs. Thereby, the sector gear Gs rotates clockwise in the figure due to the urging force of the spring SP2.

When the sector gear Gs is rotated by the spring SP2, as shown inFIG.22, the first tooth portion Gs1of the sector gear Gs engages with the second gear G12. Thereby, the drive force is transmitted from the second gear G12to the sector gear Gs, and the sector gear Gs rotates.

When the sector gear Gs rotates by a particular angle from the first sector position, a part of the sector gear Gs engages with the spring holder H (seeFIG.11), and the spring holder H rotates together with the sector gear Gs. When the first tooth portion H1of the spring holder H engages with the second gear G12, the spring holder H is rotated by the drive force from the second gear G12. Specifically, the spring holder H rotates together with the sector gear Gs in a state where the phase of the spring holder H is shifted from the phase of the sector gear Gs.

When the spring holder H rotates, the cam CM rotates clockwise in the figure. Then, as shown inFIG.23, since the distal end portion CM1of the cam CM separates from the cam contact portion452, the push-up member480rotates counterclockwise in the figure due to the urging force of the pressure plate spring SP1shown inFIG.11, and the pressure plate102moves from the separated position to the contact position.

Before the pressure plate102reaches the contact position, the controller CT switches the piston SA1of the solenoid actuator SA from the retracted position to the advanced position. Then, as shown inFIG.24, the transmission switching lever L1rotates from the transmission position to the non-transmission position, and the sector lever L2rotates from the rotation allowing position to the rotation restricting position.

When the transmission switching lever L1is located at the non-transmission position, the drive force of the motor M3is no longer transmitted to the roller gear Gr, and the second pickup roller111stops rotating. Thereby, the rotation of the second pickup roller111is stopped before the sheet S on the rising pressure plate102contacts the second pickup roller111.

When the first tooth portion Gs1of the sector gear Gs rotated by the drive force of the motor M3is disengaged from the second gear G12, the rotation of the sector gear Gs stops, and the tip of the sector lever L2enters the concave portion of the holding portion Gs6of the sector gear Gs. Since the spring holder H of which the phase is shifted from the sector gear Gs is still engaged with the second gear G12, the spring holder H rotates even after the rotation of the sector gear Gs stops.

Since the clockwise rotation of the sector gear Gs is restricted by the sector lever L2, the spring holder H rotates relative to the sector gear Gs in a stopped state, and the spring SP2located between the sector gear Gs and the spring holder H is compressed. When the first tooth portion H1of the spring holder H rotated by the drive force of the motor M3is disengaged from the second gear G12, the rotation of the spring holder H stops and the phases of the spring holder H and the sector gear Gs match.

The operation for raising the pressure plate102is summarized as follows.

When the motor M3is rotated forward to raise the pressure plate102, as shown inFIGS.22and23, the first gear G11rotates in a particular direction (counterclockwise in the figure). When the first gear G11rotates in the particular direction, the drive force is transmitted to the sector gear Gs via the first gear G11, the second one-way clutch C4and the second gear G12, which causes the sector gear Gs to rotate from the first sector position to the second sector position. Also, the drive force is transmitted to the cam CM via the sector gear Gs, which causes the cam CM to rotate from the separation corresponding position to the contact corresponding position. In other words, the drive force of the motor M3is transmitted to the cam CM through the route indicated by the thick arrows inFIGS.22and23.

The drive force transmitted to the first gear G11is also transmitted to the output gear G2through the route indicated by the thin arrows. At this time, if the rotation speed of the output gear G2and the rotation speed of the cam CM are different, the output gear G2and the cam CM may interfere with each other. In this regard, the first gear G11, the idle gears G3and G4, and the output gear G2have the same module and pitch diameter, and the second gear G12and the sector gear Gs have the same module and pitch diameter. Thus, the output gear G2rotates at the same speed as the cam CM, and thus no interference occurs between the output gear G2and the cam CM due to a difference in rotational speed.

When conveying the sheet S on the pressure plate102located at the contact position, the controller CT switches the piston SA1of the solenoid actuator SA from the advanced position to the retracted position. At this time, since the tip of the sector lever L2is in the concave portion of the holding portion Gs6of the sector gear Gs, the transmission switching lever L1switches from the non-transmission position to the transmission position relative to the sector lever L2which is substantially stopped. Thereby, the drive force of the motor M3is transmitted to the second pickup roller111, and the sheet S on the pressure plate102is conveyed by the second pickup roller111.

After conveying one sheet S to the registration roller26, the controller CT controls the solenoid actuator SA to switch the transmission switching lever L1from the transmission position to the non-transmission position.

After that, the controller CT performs an operation of switching the transmission switching lever L1from the non-transmission position to the transmission position and returning the transmission switching lever L1from the transmission position to the non-transmission position the number of times corresponding to the number of sheets S. After conveyance of the last sheet S is completed, the controller CT stops the motor M3.

After that, the controller CT reversely rotates the motor M3by a particular amount. Specifically, the controller CT reversely rotates the motor M3for a particular time such that the sector gear Gs rotates from the second sector position to the first sector position.

When the motor M3rotates in the reverse direction, as shown inFIG.25B, the first gear G11rotates in the direction opposite to the particular direction. When the first gear G11rotates in the reverse direction, the drive force of the motor M3is transmitted to the cam CM via the first gear G11, the idle gears G3and G4, the output gear G2, and the first one-way clutch C3, thereby rotating the CM from the contact corresponding position to the separation corresponding position. That is, the drive force of the motor M3is transmitted to the cam CM through the route indicated by the thick arrows inFIG.25B.

When the first gear G11starts rotating in the reverse direction, the second gear G12is kept in a stopped state due to frictional resistance with a member (not shown) and so on. Thus, the first gear G11rotates relative to the second gear G12due to the second one-way clutch C4. Here, in order to keep the second gear G12in a stopped state, for example, there is a method of pressing a friction pad against the second gear G12.

The cam CM pushes the cam contact portion452against the urging force of the pressure plate spring SP1in the process of rotating from the contact corresponding position to the separation corresponding position. Thereby, the pressing force of the cam CM is transmitted to the push-up member480via the cam contact portion452, the push-up member480rotates clockwise in the figure, and the pressure plate102moves from the contact position to the separated position. The inner surface of the concave portion CM11of the distal end portion CM1of the cam CM serves as a guiding surface for guiding the cam CM to the separation corresponding position. When the edge of the concave portion CM11on the downstream side in the rotation direction of the cam CM at the time the pressure plate102is lowered gets over the cam contact portion452, the cam contact portion452pushes the guiding surface of the concave portion CM11and the cam CM is guided to the separation corresponding position.

The drive force of the motor M3transmitted to the cam CM is transmitted to the sector gear Gs via the spring holder H. Thus, as shown inFIG.25A, the sector gear Gs rotates from the second sector position to the first sector position.

Although not shown, just before the sector gear Gs reaches the first sector position, the protrusion Gs5of the sector gear Gs contacts the sector lever L2and slightly rotates the sector lever L2from the rotation restricting position toward the rotation allowing position. When the sector lever L2rotates, the protrusion B2shown inFIG.15pushes the protrusion B1, and thus the transmission switching lever L1also rotates slightly.

Thereafter, when the protrusion Gs5of the sector gear Gs gets over the tip of the sector lever L2, the transmission switching lever L1is urged to the non-transmission position by the spring (not shown). Thereby, the transmission switching lever L1returns to the non-transmission position, and the sector lever L2also returns to the rotation restricting position and engages with the protrusion Gs5. Thereby, the positions of the members return to the positions shown inFIG.15.

In the process in which the sector gear Gs rotates from the second sector position to the first sector position, the sector gear Gs engages with the second gear G12and rotates the second gear G12. At this time, since the first gear G11, the idle gears G3and G4, and the output gear G2have the same module and pitch diameter, and the second gear G12and the sector gear Gs have the same module and pitch diameter, the second gear G12rotates at the same speed as the first gear G11. Thus, no interference occurs between the second gear G12and the first gear G11due to a difference in rotation speed.

According to the fourth embodiment, the following effects are obtained.

In a state where the pressure plate102is maintained at the contact position, the transmission switching mechanism410is switchable alternately between the transmission state and the non-transmission state. Thus, when printing a plurality of sheets S, in a state where the pressure plate102is kept at the contact position, driving and stopping the second pickup roller111is switched. This suppresses the generation of noise due to the movement of the pressure plate102when printing a plurality of sheets S.

In the fourth embodiment, the sector gear Gs has the second tooth portion Gs2and the spring holder H has the second tooth portion H2. However, a configuration may be employed in which the sector gear Gs does not have the second tooth portion Gs2and the spring holder H does not have the second tooth portion H2.

The method of returning the sector gear from the second sector position to the first sector position is not limited to the method of the fourth embodiment. For example, a cam that rotates from the contact corresponding position toward the separation corresponding position by the drive force of the motor may be rotated to a passed position that has passed the separation corresponding position, and thereafter the motor may be stopped and the cam may be returned from the passed position to the separation corresponding position by the guiding surface of the concave portion at the distal end portion of the cam. In this case, the sector gear may be located at the first sector position when the cam is located at the passed position.

Fifth Embodiment

Next, a fifth embodiment of the present disclosure will be described in detail with reference to the drawings as appropriate. Since this embodiment differs from the first embodiment described above in the structure of the sheet conveyance device, components that are substantially the same as those of the first embodiment are denoted by the same reference numerals, and descriptions thereof are omitted.

As shown inFIG.26A, a sheet conveyance device500according to the fifth embodiment includes a motor M, a push-up member580, a transmission switching mechanism510, a pressure plate operating mechanism520, and a switching mechanism530. The sheet conveyance device500also includes the manual feed tray101, the pressure plate102, and the second supply mechanism110, which are substantially the same as those of the first embodiment as shown inFIG.3.

As shown inFIG.26A, the push-up member580is a member that pushes up the pressure plate102from a separated position to a contact position. The push-up member580includes a push-up gear581and a push-up cam582.

The push-up gear581is a gear that receives drive force from the motor M via the pressure plate operating mechanism520. The push-up cam582is a cam that rotates together with the push-up gear581. The push-up cam582is switchable between a separation corresponding position indicated by a solid line in the figure and a contact corresponding position indicated by a two-dot chain line.

The push-up cam582has a contact portion582A that contacts the pressure plate102when the pressure plate102is located at the contact position. The contact portion582A is located within the range of the second pickup roller111in the width direction of the sheet S. Here, the width direction of the sheet S is the same direction as the axial direction of the second pickup roller111.

The transmission switching mechanism510is a mechanism that is switchable between a transmission state in which the drive force of the motor M is transmitted to the second pickup roller111and a non-transmission state in which the drive force of the motor M is not transmitted to the second pickup roller111. The transmission switching mechanism510includes a planetary gear mechanism540, a transmission switching lever Lt, and a cam511.

As shown inFIGS.26A and26B, the planetary gear mechanism540includes a sun gear541, a plurality of planetary gears542, a planetary carrier543as an example of a first component, and an outer gear544. The planetary gear mechanism540has a structure that, when rotation of one of the three components of the sun gear541, the planetary carrier543, and the outer gear544is stopped, the remaining components rotate in an interlocking manner.

The sun gear541is a two-stage gear. The sun gear541includes a large-diameter gear portion541A and a small-diameter gear portion541B having a smaller diameter than the large-diameter gear portion541A.

The plurality of planetary gears542are arranged around the small-diameter gear portion541B and engage with the small-diameter gear portion541B. The plurality of planetary gears542are rotatably attached to the planetary carrier543.

The planetary carrier543is rotatable about the rotation axis of the sun gear541. The planetary carrier543has a plurality of pawls543A on its outer circumferential surface.

The outer gear544is a ring-shaped member. The outer gear544has internal teeth544A located on the inner circumferential surface and external teeth544B located on the outer circumferential surface. The internal teeth544A engage with the planetary gears542. InFIG.26A,FIG.27A, and so on described later, the internal teeth544A of the outer gear544, the planetary gears542, and so on are omitted for the sake of convenience.

The external teeth544B of the outer gear544engage with a gear G51to which the drive force of the motor M is input. In this embodiment, the outer gear544is an example of an input gear to which the drive force of the motor M is input. The outer gear544and the motor M may be directly connected or may be indirectly connected via a plurality of gears. As for the other gears, similarly, the connection between two gears may be direct or indirect.

The large-diameter gear portion541A of the sun gear541engages with a gear G52that outputs drive force to the second separation roller112and the second pickup roller111.

In a state where rotation of the planetary carrier543is stopped, the drive force from the motor M is transmitted to the second separation roller112and the second pickup roller111via the planetary gear mechanism540. In a state where rotation of the planetary carrier543is allowed, the gear G52and so on act as resistance to the rotation of the sun gear541and stop the rotation of the sun gear541, thereby the drive force from the motor M is transmitted to the planetary carrier543and the planetary carrier543rotates idly. In other words, in a state where rotation of the planetary carrier543is allowed, the drive force from the motor M is not transmitted to the second pickup roller111, and thus the second pickup roller111does not rotate.

The transmission switching lever Lt is a lever for stopping or allowing rotation of the planetary carrier543. The transmission switching lever Lt is rotatable between a transmission position shown inFIG.31Band a non-transmission position shown inFIG.27B. When the transmission switching lever Lt is located at the transmission position, the transmission switching lever Lt engages with the pawl543A of the planetary carrier543and stops rotation of the planetary carrier543. Thus, when the transmission switching lever Lt is located at the transmission position, the transmission switching lever Lt causes the transmission switching mechanism510to be in the transmission state.

When the transmission switching lever Lt is located at the non-transmission position, the transmission switching lever Lt disengages from the pawl543A of the planetary carrier543, thereby allowing the planetary carrier543to rotate. Thus, when the transmission switching lever Lt is located at the non-transmission position, the transmission switching lever Lt causes the transmission switching mechanism510to be in the non-transmission state. The transmission switching lever Lt is urged from the non-transmission position toward the transmission position by a spring (not shown).

The cam511is a cam for switching the transmission switching lever Lt between the transmission position and the non-transmission position. As shown inFIG.27B, the cam511has a cam surface F1and a retracted surface F2.

The cam surface F1is a cylindrical surface of which the center is the rotation axis of a sector gear550. The cam surface F1is configured to contact the transmission switching lever Lt. The retracted surface F2is retracted farther toward the rotation axis of the sector gear550than the cam surface F1.

When the cam511rotates from the state ofFIG.31Band the cam surface F1contacts the transmission switching lever Lt, the cam surface F1causes the transmission switching lever Lt to move from the transmission position to the non-transmission position against the urging force of the spring. When the cam511rotates from the state shown inFIG.27B, the transmission switching lever Lt separates from the cam surface F1, and the retracted surface F2faces the transmission switching lever Lt, the transmission switching lever Lt moves from the non-transmission position to the transmission position by the urging force of the spring.

The cam511rotates in conjunction with the sector gear550(described later) of the pressure plate operating mechanism520. Specifically, the cam511rotates together with the sector gear550about the rotation axis of the sector gear550.

The sector gear550is configured to rotate 180 degrees, which is an example of a second angle, as will be described later. Thereby, each time the sector gear550rotates 180 degrees, the cam511is switched to the position shown inFIG.31Bor the position shown inFIG.27Band the transmission switching lever Lt is switched to the transmission position or the non-transmission position. Thus, the transmission switching mechanism510is configured to switch the state between the transmission state and the non-transmission state each time the sector gear550rotates 180 degrees.

As shown inFIG.26A, the pressure plate operating mechanism520is switchable between an operating state in which the pressure plate102is operated by using the drive force of the motor M, and a non-operating state in which the drive force of the motor M is cut off so as not to operate the pressure plate102. The pressure plate operating mechanism520includes the above-described outer gear544, the sector gear550, an interlocking gear560, a spring521, a movable gear522, a gear unit570, and the push-up member580.

As shown inFIG.27A, the sector gear550has a first tooth portion551, a second tooth portion552, a first toothless portion553, and a second toothless portion554on the outer circumferential surface. The first tooth portion551and the second tooth portion552are portions that are engageable with the external teeth544B of the outer gear544. The first toothless portion553and the second toothless portion554are portions that are not engageable with the external teeth544B of the outer gear544. The first tooth portion551, the second tooth portion552, the first toothless portion553, and the second toothless portion554are arranged on the outer circumferential surface of the sector gear550in the order of the first toothless portion553, the first tooth portion551, the second toothless portion554, and the second tooth portion552.

Specifically, toward the upstream side in the rotation direction of the sector gear550(seeFIG.28A), the first toothless portion553, the first tooth portion551, the second toothless portion554, and the second tooth portion552are arranged in this order. Here, the rotation direction of the sector gear550is the rotation direction of the sector gear550when the sector gear550receives the drive force from the outer gear544, and is the clockwise direction inFIG.28A.

The first toothless portion553is located upstream of the second tooth portion552in the rotation direction of the sector gear550. The first tooth portion551is located upstream of the first toothless portion553in the rotation direction of the sector gear550. The second toothless portion554is located upstream of the first tooth portion551in the rotation direction of the sector gear550. The second tooth portion552is located upstream of the second toothless portion554in the rotation direction of the sector gear550.

The sector gear550includes a first protrusion555, a second protrusion556, and a spring contact portion557. The first protrusion555, the second protrusion556, and the spring contact portion557protrude from a surface of the sector gear550on one side in the axial direction. The first protrusion555and the second protrusion556are protrusions with which a sector lever Ls described later is engageable.

When the sector lever Ls engages with the first protrusion555, the first toothless portion553faces the outer gear544and the drive force is not transmitted from the outer gear544to the sector gear550. As shown inFIG.31A, when the sector lever Ls engages with the second protrusion556, the second toothless portion554faces the outer gear544and the drive force is not transmitted from the outer gear544to the sector gear550.

As shown inFIG.26A, the spring contact portion557is a portion with which the spring521makes contact. The spring521urges the sector gear550in the rotation direction of the sector gear550. The spring521is, for example, a torsion spring. One end of the spring521contacts the spring contact portion557. The other end of the spring521contacts a portion13of the main housing10.

The interlocking gear560is a gear that rotates together with the sector gear550. The interlocking gear560is fixed to or integrally formed with the surface of sector gear550on the other side in the axial direction. As shown inFIG.27B, the interlocking gear560has the above-mentioned cam511on the surface opposite to the surface on which the sector gear550is located. The cam511is fixed to or integrally formed with the interlocking gear560.

As shown inFIG.27A, the interlocking gear560includes a third tooth portion561, a fourth tooth portion562, a third toothless portion563, and a fourth toothless portion564on the outer circumferential surface. The third tooth portion561and the fourth tooth portion562are portions that are engageable with the movable gear522located at a connection position (the position indicated by a two-dot chain line) described later. The number of teeth of the third tooth portion561and the fourth tooth portion562is the number that causes a downstream gear572described later to be rotated 180 degrees. Specifically, the number of teeth of the third tooth portion561and the fourth tooth portion562is the number that causes an upstream gear571described later to be rotated by an angle obtained by adding 180 degrees to the first angle.

The third toothless portion563and the fourth toothless portion564are portions that are not engageable with the movable gear522located at the connection position. The third tooth portion561, the fourth tooth portion562, the third toothless portion563, and the fourth toothless portion564are arranged on the outer circumferential surface of the interlocking gear560in the order of the third toothless portion563, the third tooth portion561, the fourth toothless portion564, and the fourth tooth portion562.

Specifically, toward the upstream side in the rotation direction of the interlocking gear560, the third toothless portion563, the third tooth portion561, the fourth toothless portion564, and the fourth tooth portion562are arranged in this order. Here, the rotation direction of the interlocking gear560is the same direction as the rotation direction of the sector gear550.

The third toothless portion563is located upstream of the fourth tooth portion562in the rotation direction of the interlocking gear560. The third tooth portion561is located upstream of the third toothless portion563in the rotation direction of the interlocking gear560. The fourth toothless portion564is located upstream of the third tooth portion561in the rotation direction of the interlocking gear560. The fourth tooth portion562is located upstream of the fourth toothless portion564in the rotation direction of the interlocking gear560.

When the sector lever Ls engages with the first protrusion555, the third toothless portion563faces the movable gear522. As shown inFIG.31A, when the sector lever Ls engages with the second protrusion556, the fourth toothless portion564faces the movable gear522.

As shown inFIG.27A, the movable gear522is movable between a connection position indicated by a two-dot chain line and a separation position indicated by a solid line. When the movable gear522is located at the connection position, the movable gear522are engageable with the third tooth portion561or the fourth tooth portion562of the interlocking gear560. Thus, when the movable gear522is located at the connection position, the movable gear522receives the drive force from the sector gear550.

When the movable gear522is located at the separation position, the movable gear522is not engageable with the third tooth portion561or the fourth tooth portion562of the interlocking gear560. Thus, when the movable gear522is located at the separation position, the movable gear522does not receive the drive force from the sector gear550. The movable gear522is rotatably supported by the sector lever Ls described later.

The gear unit570has a function of operating the pressure plate102by the drive force transmitted from the movable gear522. Specifically, the gear unit570operates the pressure plate102by transmitting the drive force transmitted from the movable gear522to the push-up member580.

The gear unit570includes an upstream gear571, a downstream gear572, and springs573. The upstream gear571engages with the movable gear522located at the connection position. In this embodiment, the upstream gear571engages with the movable gear522even when the movable gear522is located at the separation position.

The upstream gear571has two grooves571A. Each groove571A is formed in an arc shape of which the center is the rotation axis of the upstream gear571. The two grooves571A are point symmetrical with respect to the rotation axis of the upstream gear571.

The downstream gear572is a gear that rotates together with the upstream gear571when the upstream gear571rotates by the first angle or more. Here, the first angle is an angle smaller than 180 degrees, and in this embodiment, an angle smaller than 90 degrees.

The downstream gear572has two protrusions572A. The protrusions572A are fitted in the grooves571A of the upstream gear571. Specifically, one protrusion572A is fitted in one groove571A, and the other protrusion572A is fitted in the other groove571A.

One protrusion572A is separated from an upstream end μl of one groove571A in the rotation direction of the upstream gear571. Here, the rotation direction of the upstream gear571is the direction in which the upstream gear571rotates by the drive force of the motor M. The other protrusion572A is separated from an upstream end μl of the other groove571A in the rotation direction of the upstream gear571.

The spring573urges the upstream gear571toward an initial position. Here, the initial position means the position of the upstream gear571when the drive force of the motor M is not input to the upstream gear571. The initial position when the pressure plate102is located at the separated position is the position shown inFIG.27A. The initial position when the pressure plate102is located at the contact position is the position shown inFIG.31A, that is, the position rotated 180 degrees from the position shown inFIG.27A.

One spring573is arranged in each of one groove571A and the other groove571A. One spring573is located between one protrusion572A and the upstream end μl of one groove571A. The other spring573is located between the other protrusion572A and the upstream end μl of the other groove571A.

Drive force is transmitted to the downstream gear572from the upstream gear571via the spring573. Specifically, as shown inFIG.29A, when the upstream gear571rotates from the initial position within a range less than the first angle, the spring573is compressed between the upstream gear571and the downstream gear572, and the downstream gear572does not rotate. As shown inFIG.30A, when the upstream gear571rotates from the initial position by an angle of the first angle or more, the upstream gear571pushes the downstream gear572via the spring573, causing the downstream gear572to rotate together with the upstream gear571.

When all the teeth of the third tooth portion561or the fourth tooth portion562of the interlocking gear560push the teeth of the movable gear522, the downstream gear572rotates 180 degrees. The downstream gear572engages with the push-up gear581. Thus, each time the downstream gear572rotates 180 degrees, the push-up member580also rotates 180 degrees.

As shown inFIG.26A, the switching mechanism530is a mechanism for switching the state of the pressure plate operating mechanism520. The switching mechanism530includes the sector lever Ls, a solenoid actuator SA, and a spring531.

The sector lever Ls is rotatable between a rotation restricting position indicated by a solid line in the figure and a rotation allowing position indicated by a two-dot chain line. When the sector lever Ls is located at the rotation restricting position, by engaging with the first protrusion555or the second protrusion556of the sector gear550, the sector lever Ls stops rotation of the sector gear550due to the urging force of the spring521. When the sector lever Ls is located at the rotation allowing position, by separating from the first protrusion555or the second protrusion556of the sector gear550, the sector lever Ls allows rotation of the sector gear550due to the urging force of the spring521.

One end of the sector lever Ls engages with the first protrusion555or the second protrusion556. The other end of the sector lever Ls rotatably supports the movable gear522. A rotation shaft of the sector lever Ls is located between one end and the other end of the sector lever Ls.

When the sector lever Ls is located at the rotation restricting position, the movable gear522is located at the separation position. When the sector lever Ls is located at the rotation allowing position, the movable gear522is located at the connection position.

The solenoid actuator SA is an actuator for moving the sector lever Ls between the rotation restricting position and the rotation allowing position. The solenoid actuator SA includes a piston SA1that advances and retracts. The piston SA1engages with the sector lever Ls. The piston SA1is movable between an advanced position shown in the figure and a retracted position (not shown).

The spring531urges the sector lever Ls from the rotation allowing position toward the rotation restricting position.

When the solenoid actuator SA is energized, the solenoid actuator SA is actuated, and the piston SA1moves from the advanced position to the retracted position to pull the sector lever Ls. Thereby, the sector lever Ls moves from the rotation restricting position to the rotation allowing position against the urging force of the spring531.

When energization of the solenoid actuator SA is stopped, the piston SA1moves from the retracted position to the advanced position. Thereby, the sector lever Ls moves from the rotation allowing position to the rotation restricting position by the urging force of the spring531.

As shown inFIG.26A, the controller CT includes a CPU, a ROM, a RAM, a non-volatile memory, and so on, and is configured to perform various controls based on programs prepared in advance. The controller CT has a function of, when printing a plurality of sheets S, moving the pressure plate102from the separated position to the contact position, and then intermittently driving the second pickup roller111to convey a plurality of sheets S, without moving the pressure plate102from the contact position.

The operation of the controller CT will be described in detail below. In a state where the controller CT does not receive a print instruction, the position of each component is the position shown inFIG.26A.

In response to receiving a print instruction for printing a plurality of sheets S, the controller CT first rotates the motor M. Then, the gear G51, the outer gear544, and the planetary carrier543rotate.

After that, when the controller CT energizes the solenoid actuator SA to operate the solenoid actuator SA, as shown inFIG.28A, the sector lever Ls rotates from the rotation restricting position to the rotation allowing position. Thereby, the sector lever Ls separates from the first protrusion555of the sector gear550, and the movable gear522moves from the separation position to the connection position.

When energizing the solenoid actuator SA for the first time after receiving a print instruction, the controller CT sets an energizing time to a first time required to move the pressure plate102from the separated position to the contact position. Thus, the actuation time of the solenoid actuator SA is the first time, and the sector lever Ls is maintained at the rotation allowing position during the first time.

When the sector lever Ls separates from the first protrusion555, as shown inFIGS.28A and28B, the sector gear550, the interlocking gear560, and the cam511rotate by the urging force of the spring521shown inFIG.26A. Thereby, the first tooth portion551of the sector gear550engages with the outer gear544, and the third tooth portion561of the interlocking gear560engages with the movable gear522located at the connection position.

In the present embodiment, a first timing at which the first tooth portion551engages with the outer gear544is substantially the same as a second timing at which the third tooth portion561engages with the movable gear522. However, the second timing may be later than the first timing.

When the sector gear550is connected to the outer gear544and the interlocking gear560is connected to the movable gear522, the drive force of the motor M is transmitted from the outer gear544to the movable gear522via the sector gear550and the interlocking gear560. This causes the movable gear522and the upstream gear571to rotate.

When the upstream gear571rotates, as shown inFIG.29A, the springs573are compressed between the upstream gear571and the downstream gear572. During this time, the downstream gear572does not move.

When the upstream gear571rotates from the initial position by the first angle or more, as shown inFIG.30A, the upstream gear571pushes the downstream gear572via the springs573, and thus the downstream gear572rotates together with the upstream gear571. When the downstream gear572rotates, the push-up member580rotates from the separation corresponding position to the contact corresponding position, and the pressure plate102rotates from the separated position toward the contact position.

When the third tooth portion561of the interlocking gear560separates from the movable gear522located at the connection position, as shown inFIG.31A, the downstream gear572stops at a position rotated 180 degrees from the initial position. Thereby, the push-up member580stops at the contact corresponding position, and the pressure plate102is maintained at the contact position.

Further, when the third tooth portion561of the interlocking gear560separates from the movable gear522, due to the urging force of the spring573, the upstream gear571rotates relative to the stopped downstream gear572and moves to the initial position.

After the first time has elapsed since the start of energization of the solenoid actuator SA, the controller CT stops energizing the solenoid actuator SA. The first time is set to be longer than a time from the start of energization of the solenoid actuator SA until the downstream gear572rotates 180 degrees from the initial position.

When the energization of the solenoid actuator SA is stopped, the sector lever Ls rotates from the rotation allowing position to the rotation restricting position. Thereby, the sector lever Ls becomes engageable with the second protrusion556of the sector gear550, and the movable gear522moves from the connection position to the separation position.

When the first tooth portion551of the sector gear550separates from the outer gear544, the drive force of the motor M is no longer transmitted to the sector gear550, but the sector gear550rotates due to the urging force of the spring521. Thereby, the second protrusion556of the sector gear550engages with the sector lever Ls located at the rotation restricting position, and the rotation of the sector gear550is stopped. That is, the sector gear550stops at a position rotated 180 degrees from the position shown inFIG.27A.

As the sector gear550rotates 180 degrees, as shown inFIGS.27B to31B, the cam511also rotates 180 degrees. Since the cam surface F1of the cam511separates from the transmission switching lever Lt, the transmission switching lever Lt moves from the non-transmission position to the transmission position. Thereby, the state of the transmission switching mechanism510is switched from the non-transmission state to the transmission state.

When the transmission switching lever Lt moves from the non-transmission position to the transmission position, rotation of the planetary carrier543is stopped. Thereby, the sun gear541rotates together with the outer gear544, and thus the second pickup roller111rotates and the conveyance of the first sheet S is started.

In order to convey the sheet S to the registration roller26by the second pick-up roller111that is rotating, a particular time after energization of the solenoid actuator SA is stopped, the controller CT performs energization of the solenoid actuator SA during a second time. Here, the second time is a period of time during which the upstream gear571rotates less than the first angle, and is shorter than the first time.

When the actuation time of the solenoid actuator SA is the second time, as shown inFIGS.32A to34A, the movable gear522is located at the connection position during the second time and then moves to the separation position. Since the drive force of the motor M is transmitted to the upstream gear571during the second time, the upstream gear571rotates by a small angle less than the first angle, and then returns to the initial position by the urging force of the spring573. Thus, when the actuation time of the solenoid actuator SA is the second time, the downstream gear572does not rotate. Thus, the position of the pressure plate102is maintained at the contact position.

When the actuation time of the solenoid actuator SA is the second time, too, the sector gear550rotates 180 degrees and then stops. Specifically, after the sector lever Ls separates from the second protrusion556, the sector gear550rotates 180 degrees by the urging force of the spring521and the drive force from the outer gear544, and then stops due to engagement of the first protrusion555with the sector lever Ls. Thereby, as shown inFIGS.32B to34B, since the cam surface F1of the cam511pushes the transmission switching lever Lt, the transmission switching lever Lt moves from the transmission position to the non-transmission position, and the state of transmission switching mechanism510is switched from the transmission state to the non-transmission state.

After that, the controller CT performs a short-time energization process of energizing the solenoid actuator SA during the second time for the number of times corresponding to the remaining sheets S. Specifically, in order to convey one sheet S, the controller CT performs the short-time energization process twice, thereby switching the state of the transmission switching mechanism510from the non-transmission state to the transmission state and then switching from the transmission state to the non-transmission state. The interval between two short-time energization processes corresponding to one sheet S is set to an interval corresponding to the time required to convey one sheet S to the registration roller26.

When conveying the last sheet S, the controller CT performs the short-time energization process once, and then performs a long-time energization process once in which the solenoid actuator SA is energized during the first time. Thereby, in the short-time energization process the conveyance of the sheet S is started while the pressure plate102is maintained at the contact position, and in the long-time energization process the rotation of the second pick-up roller111is stopped and the position of the pressure plate102is returned to the separated position.

That is, when printing a plurality of sheets S, for the first sheet S, the controller CT performs the long-time energization process, and then performs the short-time energization process, thereby moving the pressure plate102to the contact position and conveying the first sheet S. When printing sheets S other than the last sheet S among the remaining sheets S, the controller CT performs two short-time energization processes on one sheet S, thereby conveying the sheets S one sheet at a time while maintaining the pressure plate102at the contact position. When printing the last sheet S, the controller CT performs the short-time energization processing and then performs the long-time energization process, thereby conveying the last sheet S and then moving the pressure plate102to the separated position.

As described above, according to the fifth embodiment, the following effects are obtained.

When the solenoid actuator SA is actuated during the second time shorter than the first time in a state where the pressure plate102is located at the contact position, the state of the transmission switching mechanism510is switched to the transmission state or the non-transmission state while the pressure plate102is maintained at the contact position. Thus, when printing a plurality of sheets S, driving and stopping the second pickup roller111is switched while maintaining the pressure plate102at the contact position. Thus, when printing a plurality of sheets S, the generation of noise due to the movement of the pressure plate102is suppressed.

Sixth Embodiment

Next, a sixth embodiment of the present disclosure will be described in detail with reference to the drawings as appropriate. Since the sixth embodiment is obtained by changing the position of the gear unit570in the above-described fifth embodiment, components that are substantially the same as those of the fifth embodiment are denoted by the same reference numerals, and description thereof are omitted.

As shown inFIGS.35A and35B, the upstream gear571of the gear unit570of the sixth embodiment is located at a position where the upstream gear571engages with the movable gear522located at the connection position and does not engage with the movable gear522located at the separation position. According to the sixth embodiment, the movable gear522is moved smoothly.

Seventh Embodiment

Next, a seventh embodiment of the present disclosure will be described in detail with appropriate reference toFIG.36. The present embodiment is obtained by partially changing the structure of the sheet conveyance device400according to the fourth embodiment. Thus, the components that are substantially the same as those of the fourth embodiment are denoted by the same reference numerals, and descriptions thereof are omitted.

As shown inFIG.36, in a sheet conveyance device600according to the seventh embodiment, the positions of the push-up members480are different from that in the first embodiment. In the seventh embodiment, the contact portions481of the push-up members480are located outside the range of the second pickup roller111in the width direction of the sheet S. The push-up members480are located on one end side and the other end side of the sheet S in the width direction.

The drive shaft450has gear portions451that engage with the gear portions482of the push-up members480on one end side and the other end side. The cam contact portion452is formed integrally with the gear portion451on the one end side. In the seventh embodiment, only the positions of the push-up members480and so on are different and the rest of the structure is the same as that of the fourth embodiment. Thus, the same effects as those of the fourth embodiment are obtained.

While the invention has been described in conjunction with various example structures outlined above and illustrated in the figures, various alternatives, modifications, variations, improvements, and/or substantial equivalents, whether known or that may be presently unforeseen, may become apparent to those having at least ordinary skill in the art. Accordingly, the example embodiments of the disclosure, as set forth above, are intended to be illustrative of the invention, and not limiting the invention. Various changes may be made without departing from the spirit and scope of the disclosure. Thus, the disclosure is intended to embrace all known or later developed alternatives, modifications, variations, improvements, and/or substantial equivalents. Some specific examples of potential alternatives, modifications, or variations in the described invention are provided below.

In the fifth embodiment, the movable gear may be linearly movable.

In the fifth embodiment, the sector lever and the movable gear may be configured to be moved by separate drive sources. In this case, the controller may drive the first drive source to move the sector lever to the rotation allowing position, and drive the second drive source to move the movable gear to the connection position. Alternatively, the controller may drive the first drive source to move the sector lever to the rotation restricting position, and drive the second drive source to move the movable gear to the separation position.

The transmission switching lever is configured to switch between the transmission position and the non-transmission position. The transmission switching lever may be linearly movable, for example.

The first component of the planetary gear mechanism with which the transmission switching lever engages may be the sun gear or the outer gear.

In the fifth embodiment, the cam and the sector gear may not be integrated, and may be separately formed. In this case, for example, the cam and the sector gear may be directly connected by gear teeth or indirectly connected via a particular number of gears.

In the fifth embodiment, the interlocking gear and the sector gear may not be integrated, and may be separately formed. In this case, for example, the interlocking gear and the sector gear may be directly connected by gear teeth or indirectly connected via a particular number of gears.

The transmission switching mechanism may be, for example, a pendulum gear. In this case, the pendulum gear is rotatable between a transmission position where the drive force of the motor is transmitted to the supply roller and a non-transmission position where the drive force of the motor is not transmitted to the supply roller. The pendulum gear is switched between the transmission position and the non-transmission position each time the sector gear rotates by the second angle.

In the fifth embodiment, the second angle is not limited to 180 degrees, and may be 120 degrees or 90 degrees, for example. In a case where the second angle is 120 degrees, the sector gear may have three tooth portions and three toothless portions. In a case where the second angle is 90 degrees, the sector gear may have four tooth portions and four toothless portions.

The pressure plate operating mechanism is not limited to the structure of the above-described embodiments, and may have any structure.

In the fifth embodiment, the states of the pressure plate operating mechanism and the transmission switching mechanism are switched by the sector lever Ls, the solenoid actuator SA, the cam511, and the transmission switching lever Lt. The present disclosure is not limited to this. Any structure may be adopted as long as the states of the pressure plate operating mechanism and the transmission switching mechanism are switched using the solenoid actuator. Specifically, the structure may be such that, when the actuation time of the solenoid actuator is the first time, the state of the pressure plate operating mechanism is switched to the operating state to move the pressure plate and the state of the transmission switching mechanism is switched to the transmission state or the non-transmission state, and when the actuation time of the solenoid actuator is the second time shorter than the first time, the state of the pressure plate operating mechanism is not switched to the operating state to maintain the position of the pressure plate and the state of the transmission switching mechanism is switched to the transmission state or the non-transmission state.

In the fifth embodiment, the interlocking gear is not necessarily required. In this case, for example, the movable gear may be movable between a connection position where the movable gear engages with the sector gear and a separation position where the movable gear separates from the sector gear.

In the fifth embodiment, the input gear is not limited to the outer gear, and may be a gear that engages directly or indirectly with the outer gear of the fifth embodiment, for example.

The springs are not limited to those in the above embodiments, and may be other springs such as a wire spring and a leaf spring.

In the above-described embodiment, the entirety of the contact portion of the push-up member is located within the range of the supply roller in the width direction of the sheet. Alternatively, at least part of the contact portion of the push-up member may be located within the range of the supply roller in the width direction of the sheet. For example, only part of the contact portion may be located within the range of the supply roller in the width direction of the sheet.

The supply roller may be located at a position different from the center in the width direction with respect to the sheet on the manual feed tray.

The pressure plate and the push-up member may be linearly movable.

The first component, the second component, and the third component are not limited to the members exemplified in the above embodiments, and may be changed as appropriate.

Each element described in the above embodiments and modifications may be implemented in any combination.