Sheet conveying device, and image forming apparatus including the sheet conveying device

A sheet conveying device comprising:

• a conveying roller configured to convey a sheet member, conveyed from upstream in a conveying direction of the sheet member, toward downstream in the conveying direction of the sheet member;
• a drive motor configured to rotationally drive the conveying roller;
• a first detection portion configured to detect a rotating state of the drive motor;
• a second detection portion configured to detect, at a predetermined position upstream of the conveying roller in the conveying direction of the sheet member, a front end of the sheet member conveyed from upstream in the conveying direction of the sheet member;
• a third detection portion configured to detect the rotating state of the drive motor at a lower detection accuracy than the first detection portion;
• a lock determination portion configured to perform a process of determining that the drive motor is locked when a detection value of the first detection portion and a detection value of the third detection portion do not match;
• and
• a control portion configured to control an operation of the drive motor, the control portion including:
• a first drive control portion configured to, when the front end is detected by the second detection portion, set driving of the drive motor in a stopped state before the sheet member makes contact with the conveying roller;
• a rotation amount calculation portion configured to perform, based on a detection signal of the first detection portion, a process of calculating a rotation amount of the conveying roller after the sheet member conveyed from upstream in the conveying direction of the sheet member makes contact with the conveying roller;
• and
• a second drive control portion configured to start driving of the drive motor at a timing in accordance with the rotation amount of the conveying roller calculated by the rotation amount calculation portion;
• and
• a third drive control portion configured to, after the front end is detected by the second detection portion, rotate the drive motor in a reverse direction that is a rotation direction for conveying the sheet member upstream in the conveying direction of the sheet member at a speed lower than a predetermined rotational speed, wherein
• the third drive control portion stops the reverse rotation of the drive motor before elapsing of a lock determination time required by the lock determination portion for determining that the drive motor is locked.