Sheet width regulating device and image forming apparatus with sheet width regulating device

1. A sheet width regulating device, comprising:

a base plate on which a sheet having one end and the other end parallel to each other is to be placed;

a regulating member which regulates one end of the sheet;

a first moving cursor which is a member for regulating the other end of the sheet, stands on an upper surface of the base plate and is movable in a way perpendicular to a direction along the other end of the sheet;

a first rack that extends in the way on the upper surface of the base plate;

a second rack that is spaced apart from and extends in parallel with the first rack;

a first pinion that is attached to the first moving cursor and engaged with the first rack;

a second pinion that is attached to the first moving cursor and engaged with the second rack; and

a coupling shaft that rotates the first and second pinions simultaneously; wherein

the first moving cursor further includes a locking portion for locking rotation of at least one of the first and second pinions about an axis of the pinion, and

the locking portion includes:

a locking member engaged with a peripheral surface of the at least one pinion from above; and

a switching member for switching a position of the locking member between a position where the locking member is engaged with the at least one pinion and a position where the locking member is spaced apart from the at least one pinion.

2. A sheet width regulating device according to claim 1 , wherein the first and second pinions are so arranged that a central position of the first moving cursor in a direction along the other end is located between the first and second pinions.

3. A sheet width regulating device according to claim 1 , wherein the first moving cursor further includes:

a first engaging portion which is provided near the first rack and engaged with the base plate slidably in a direction parallel with the first rack; and

a second engaging portion which is provided near the second rack and engaged with the base plate slidably in a direction parallel with the second rack.

4. A sheet width regulating device according to claim 3 , wherein the base plate is slidably engaged with the first engaging portion along a sliding direction parallel with the first rack near the first rack.

5. A sheet width regulating device according to claim 3 , wherein the first engaging portion includes a projection projecting in a direction perpendicular to the sliding direction on a lower surface of the base plate.

6. A sheet width regulating device according to claim 1 , wherein:

the regulating member is a second moving cursor which stands on the upper surface of the base plate and is movable in the way; and

the sheet width regulating device further comprises a moving mechanism for moving the first and second cursors simultaneously in opposite directions along the way.

7. A sheet width regulating device according to claim 1 , wherein the first moving cursor further includes a locking portion for locking at least one of the first and second pinions to prevent a movement of the at least one of the first and second pinions along the respective rack for engaging the at least one of the first and second pinions out of the first and second racks.

8. A sheet width regulating device according to claim 1 , wherein the locking member includes a tooth to be engaged with teeth of the at least one pinion located downstream of a top of the at least one pinion in a rotation direction of the at least one pinion when the first moving cursor is moved in a direction away from the regulating member, but includes no tooth located upstream of the top of the at least one pinion.

9. A sheet width regulating device according to claim 1 , wherein the switching member is a member, the position of which is switched according to a user's operation, and arranged at an upper part of the first moving cursor.

10. An image forming apparatus, comprising:

a sheet width regulating device according to claim 1 ; and

an image forming unit for forming an image on a sheet fed from the sheet width regulating device.