Method for compensating a gear backlash and apparatus for carrying out said method

An apparatus for compensating gear backlash of a geared motor that can be operated in reverse operation to adjust a print web in an electrophotographic printing device, comprising:

• a control connected to the geared motor to rotate the geared motor in a first direction of rotation until a first end position is reached and to rotate the geared motor in an opposite direction of rotation, said opposite direction of rotation being opposite to said first direction, said control rotating said geared motor to a second end position in said opposite direction and then rotating said geared motor in said first direction from said second end position;
• a first Hall effect sensor mounted to acquire a gear backlash at a point of reversal of the rotational motion at said first end position, said first sensor producing a first sensor output signal;
• a second Hall effect sensor mounted to acquire a gear backlash at a point of reversal of the rotational motion at said second end position, said second sensor producing a second sensor output signal;
• a calculator connected to receive the first and second sensor output signals to calculate a time that elapses during a change of direction of rotation of the geared motor until the sensor output decays, said time indicating the gear backlash, said calculator providing said time to said control to apply the time in the reverse operation of the geared motor for a correspondingly longer drive of the geared motor in order to compensate the gear backlash;
• and
• a control bar connected to said geared motor and a drive roller connected to said control bar to effect guiding of the print web.

A method for compensating a gear backlash of a geared motor that can be operated in reverse operation in an electrophotographic printing machine, comprising the steps of:

• rotating the geared motor in a first direction of rotation until an end position is reached;
• rotating the geared motor in an opposite rotation direction to said first direction of rotation;
• acquiring a gear backlash at a point of reversal of rotational motion by a sensor;
• calculating a time that elapses during a change of direction of rotation without change in output of the sensor using an output of the sensor, said time indicating gear backlash of the geared motor;
• applying the time calculated in said calculating step for a correspondingly longer driving of the geared motor in order to compensate the gear backlash determined in this way;
• the sensor being a Hall sensor that acquires an end position;
• said step of rotating in the opposite direction taking place until a signal from the Hall sensor decays;
• and
• said geared motor being an adjustment motor for aligning a print medium web by a web guide device in a printer and said steps of rotating said geared motor adjusts said web guide device.

An apparatus for compensating a gear backlash of a geared motor that can be operated in reverse operation in an electrophotographic printing machine, comprising:

• a web guiding device including
• a drive roller over which a web of print medium moves during a printing operation, and
• control bar connected to said drive roller vary a position of said drive roller;
• a geared motor connected to said control bar, said geared motor being rotatable in first and second opposite directions to move said control bar;
• two sensors mounted to sense movement of said web guiding device separately in each direction of rotation of said geared motor;
• and
• a controller connected to said geared motor and to said two sensors to determine a time between a start of rotation of said geared motor in an opposite direction and a sensing of movement by said web guiding device by a corresponding one of said two sensors.