Sheet processing machine

A sheet processing machine that processes a sheet while conveying the sheet in a conveyance direction, the sheet processing machine comprising:

• a processing device including a rotary processing blade;
• a drive shaft that extends in a width direction orthogonal to the conveyance direction and is driven to rotate the rotary processing blade;
• a shaft drive motor that drives the drive shaft;
• a rotational position detector that detects a rotational position of the drive shaft;
• a width direction drive motor that moves the processing device in the width direction;
• and
• a control unit that controls operations of the shaft drive motor and the width direction drive motor,
• wherein the control unit controls the shaft drive motor so that the drive shaft is at a predetermined rotational position based on the rotational position of the drive shaft detected by the rotational position detector, and controls the width direction drive motor so that the processing device moves to a predetermined processing position while the drive shaft maintains the predetermined rotational position,
• the rotational position detector includes:
• a portion-to-be-detected fixed to one end of the drive shaft and located radially outside of the drive shaft;
• and
• a rotational position sensor that detects a rotational position of the portion-to-be-detected,
• the portion-to-be-detected includes a reflecting surface,
• the rotational position sensor is a reflective optical sensor having a detection surface provided with a light emitting unit that emits a measurement light and a light receiving unit that receives a reflected light obtained by reflecting the measurement light by the reflecting surface, and
• the reflecting surface is configured to face the detection surface in a spaced apart manner,
• the sheet processing machine further comprise a stray light suppressor that prevents stray light not reflected by the reflecting surface from entering the light receiving unit.

A sheet processing machine that processes a sheet while conveying the sheet in a conveyance direction, the sheet processing machine comprising:

• a processing device including a rotary processing blade;
• a drive shaft that extends in a width direction orthogonal to the conveyance direction and is driven to rotate the rotary processing blade;
• a shaft drive motor that drives the drive shaft;
• a rotational position detector that detects a rotational position of the drive shaft;
• a width direction drive motor that moves the processing device in the width direction;
• and
• a control unit that controls operations of the shaft drive motor and the width direction drive motor,
• a stray light suppressing structure that prevents stray light not reflected by the reflecting surface from entering the light receiving unit,
• the processing device has a reference end serving as a processing reference position when moving in the width direction, and
• the width direction drive motor moves the processing device based on the processing reference position,
• the rotational position detector includes:
• a portion-to-be-detected fixed to one end of the drive shaft and located radially outside of the drive shaft;
• and
• a rotational position sensor that detects a rotational position of the portion-to-be-detected,
• the portion-to-be-detected includes a reflecting surface,
• the rotational position sensor is a reflective optical sensor having a detection surface provided with a light emitting unit that emits a measurement light and a light receiving unit that receives a reflected light obtained by reflecting the measurement light by the reflecting surface, and
• the reflecting surface is configured to face the detection surface in a spaced apart manner,
• the sheet processing machine further comprise a stray light suppressor that prevents stray light not reflected by the reflecting surface from entering the light receiving unit.