Drum conveyance mechanism and image forming apparatus
A drum conveyance mechanism includes a drum, a drive motor to rotate the drum to convey a sheet medium along an outer circumferential surface of the drum, a first power supply to supply an operating voltage to the drive motor, a driven roller to rotate as the drum rotates, a rotation brake to prevent rotation of the driven roller, a second power supply to supply an operating voltage to the rotation brake, and a power supply switch to switch a state of supply of the operating voltage from the first power supply and the second power supply.
1 . A drum conveyance mechanism comprising:
a drum;
a drive motor configured to rotate the drum to convey a sheet medium along an outer circumferential surface of the drum;
a first power supply configured to supply an operating voltage to the drive motor;
a driven roller configured to rotate as the drum rotates;
a rotation brake configured to prevent rotation of the driven roller;
a second power supply configured to supply an operating voltage to the rotation brake; and
a power supply switch configured to switch a state of supply of the operating voltage from the first power supply and the second power supply, wherein
the power supply switch is further configured
not to supply the operating voltage from the second power supply to the rotation brake in a first state where the operating voltage is supplied from the first power supply to the drive motor, and
to supply the operating voltage from the second power supply to the rotation brake in a second state, as a state of non-supply, where the operating voltage from the first power supply to the drive motor is interrupted, and
the power supply switch includes
an a-contact switch having an input end and an output end, the input end of the a-contact switch coupled to the first power supply, the output end of the a-contact switch coupled to the drive motor, the a-contact switch closed in the first state, the a-contact switch opened in the second state, and
a b-contact switch having an input end and an output end, the input end of the b-contact switch coupled to the second power supply, the output end of the b-contact switch coupled to the rotation brake, the b-contact switch opened in the first state, the b-contact switch closed in the second state.
2 . The drum conveyance mechanism according to claim 1 ,
wherein the power supply switch switches the state of supply from the first state to the second state according to an external input.
3 . The drum conveyance mechanism according to claim 2 ,
wherein the power supply switch further includes
a coil configured to control opening and closing of the a-contact switch and the b-contact switch in response to the external input,
wherein the coil is energized or nonenergized in response to the external input, to switch the state of supply of the operating voltage from the first power supply and the second power supply.
4 . The drum conveyance mechanism according to claim 1 ,
wherein the first power supply is an alternating-current power supply, and
wherein the second power supply is a direct-current power supply to convert voltage applied by the alternating-current power supply into a direct-current voltage.
5 . The drum conveyance mechanism according to claim 1 , further comprising
a pair of rotation brakes including the rotation brake,
wherein the pair of rotation brakes are disposed upstream from and downstream from the drum in a conveyance direction of the sheet medium.
6 . An image forming apparatus comprising:
an image forming device to form an image on a sheet medium; and
a conveyor to convey the sheet medium to the image forming device,
the conveyor including a drum conveyance mechanism including
a drum;
a drive motor configured to rotate the drum to convey a sheet medium along an outer circumferential surface of the drum;
a first power supply configured to supply an operating voltage to the drive motor,
a driven roller configured to rotate as the drum rotates,
a rotation brake configured to prevent rotation of the driven roller,
a second power supply configured to supply an operating voltage to the rotation brake, and
a power supply switch configured to switch a state of supply of the operating voltage from the first power supply and the second power supply, wherein
the power supply switch is further configured
not to supply the operating voltage from the second power supply to the rotation brake in a first state where the operating voltage is supplied from the first power supply to the drive motor, and
to supply the operating voltage from the second power supply to the rotation brake in a second state, as a state of non-supply, where the operating voltage from the first power supply to the drive motor is interrupted, and
the power supply switch includes
an a-contact switch having an input end and an output end, the input end of the a-contact switch coupled to the first power supply, the output end of the a-contact switch coupled to the drive motor, the a-contact switch closed in the first state, the a-contact switch opened in the second state, and
a b-contact switch having an input end and an output end, the input end of the b-contact switch coupled to the second power supply, the output end of the b-contact switch coupled to the rotation brake, the b-contact switch opened in the first state, the b-contact switch closed in the second state.