A drive transmission mechanism, comprising:
- a first ratchet mechanism that transmits a rotational driving force from a drive source to a first driven member;
- and
- a second ratchet mechanism that transmits a rotational driving force from the drive source to a second driven member,
- wherein
- the first ratchet mechanism includes
- a first drive input gear to which a rotational driving force of the drive source is inputted,
- a first drive output gear that is disposed on a same axis as the first drive input gear, and that outputs a rotational driving force of the drive source to the first driven member, and
- a first coupling member that is disposed between the first drive input gear and the first drive output gear so as to be capable of performing a thrust movement, and that rotates along with the first drive input gear,
- the second ratchet mechanism includes
- a second drive input gear to which a rotational driving force of the drive source in inputted,
- a second drive output gear that is disposed on a same axis as the second drive input gear, and that outputs a rotational driving force of the drive source to the second driven member, and
- a second coupling member that is disposed between the second drive input gear and the second drive output gear so as to be capable of performing a thrust movement, and that rotates along with the second drive input gear,
- each of the first coupling member and the second coupling member has a first ratchet tooth that is formed on a surface thereof that faces the first drive output gear or the second drive output gear,
- each of the first drive output gear and the second drive output gear has a second ratchet tooth that is formed on a surface thereof that faces the first coupling member or the second coupling member, and that meshes with the first ratchet tooth,
- when the drive source rotates in a forward direction,
- the first ratchet mechanism rotates in a direction in which drive coupling surfaces of the first ratchet tooth and the second ratchet tooth mesh with each other, and thereby the first ratchet mechanism enters a drive coupling state for transmitting a driving force to the first driven member, and
- the second ratchet mechanism rotates in a direction in which non-drive coupling surfaces of the first ratchet tooth and the second ratchet tooth mesh with each other, and thereby the second ratchet mechanism enters a non-drive coupling state for transmitting no driving force to the second driven member,
- when the drive source rotates in a reverse direction,
- the first ratchet mechanism rotates in a direction in which the non-drive coupling surfaces mesh with each other, and thereby the first ratchet mechanism enters a non-drive coupling state for transmitting no driving force to the first driven member, and
- the second ratchet mechanism rotates in a direction in which the drive coupling surfaces mesh with each other, and thereby the second ratchet mechanism enters a drive coupling state for transmitting a driving force to the second driven member,
- between the first ratchet mechanism and the second ratchet mechanism, a link member is disposed that assists switching between the drive coupling state and the non-drive coupling state of the first ratchet mechanism and the second ratchet mechanism, and
- due to a thrust movement of the first coupling member in a direction separating from the first drive output gear, the link member causes the second coupling member to move in a direction approaching the second drive output gear, and, due to a thrust movement of the second coupling member in a direction separating from the second drive output gear, the link member causes the first coupling member to move in a direction approaching the first drive output gear.