Method and apparatus for forming image
AssigneesKabushiki Kaisha Toshiba, Toshiba Tec Kabushiki Kaisha
InventorTatsuyuki Miura
Life of this patent
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Abstract
A movable light beam is controlled and set within a tolerable range of a beam position A by using a galvano-mirror, and then a circuit offset relating to the beam position A is measured. With the circuit offset being subtracted, the movable laser beam is exactly controlled and set at the beam position A, and an output value DA from a sensor at that time is stored. Subsequently, an output value DB from the sensor is similarly stored in connection with a beam position B. An ultimate beam position of the movable laser beam M is controlled such that a difference between the output values DA and DB coincides with a difference between an output value DS of the sensor with respect to a stationary laser beam S and an output value DM of the sensor in connection with the movable laser beam M.
Claims4
A beam position adjusting method for an optical scanning device using a galvano-mirror capable of altering an angle of a mirror surface by a drive control, and using a sensor that detects passage positions of a stationary light beam whose scanning position is fixed and a movable light beam whose scanning position is varied by adjusting the angle of the mirror surface of the galvano-mirror, the method comprising:
- effecting a control to position the movable light beam within the tolerable range of a first passage target position by adjusting the angle of the mirror surface of the galvano-mirror, and measuring a first circuit offset in a detection circuit for an output of the sensor at a time when emission of the movable light beam is stopped;
- emitting the movable light beam once again, effecting a control to position the movable light beam at the first passage target position with the first circuit offset being subtracted, and storing a first output value from the sensor at a time when the movable light beam is controlled and set at the first passage target position;
- effecting a control to position the movable light beam within the tolerable range of a second passage target position by adjusting the angle of the mirror surface of the galvano-mirror, and measuring a second circuit offset in the detection circuit for the output of the sensor at a time when emission of the movable light beam is stopped;
- emitting the movable light beam once again, effecting a control to position the movable light beam at the second passage target position with the second circuit offset being subtracted, and storing a second output value from the sensor at a time when the movable light beam is controlled and set at the second passage target position;
- and
- controlling the angle of the mirror surface of the galvano-mirror such that a difference between a third output value from the sensor at a time when the stationary light beam passes through the lightreceiving surface of the sensor and a fourth output value from the sensor at a time when the movable light beam passes through the light-receiving surface of the sensor coincides with a difference between the first output value and the second output value.
An image forming method for an image forming apparatus having an optical scanning device using a galvano-mirror capable of altering an angle of a mirror surface by a drive control, and using a sensor that detects passage positions of a stationary light beam whose scanning position is fixed and a movable light beam whose scanning position is varied by adjusting the angle of the mirror surface of the galvano-mirror, the method comprising:
- effecting, a control to position the movable light beam within a tolerable range of a predetermined first passage target position by adjusting the angle of the mirror surface of the galvano-mirror, and measuring a first circuit offset in a detection circuit for an output of the sensor at a time when emission of the movable light beam is stopped;
- emitting the movable light beam once again, effecting a control to position the movable light beam at the first passage target position with the first circuit offset being subtracted, and storing a first output value from the sensor at a time when the movable light beam is controlled and set at the first passage target position;
- effecting a control to position the movable light beam within a tolerable range of a predetermined second passage target position by adjusting the angle of the mirror surface of the galvano-mirror, and measuring a second circuit offset in the detection circuit for the output of the sensor at a time when emission of the movable light beam is stopped;
- emitting the movable light beam once again, effecting a control to position the movable light beam at the second passage target position with the second circuit offset being subtracted, and storing a second output value from the sensor at a time when the movable light beam is controlled and set at the second passage target position;
- controlling the angle of the mirror surface of the galvano-mirror such that a difference between a third output value from the sensor at a time when the stationary light beam passes through the light-receiving surface of the sensor and a fourth output value from the sensor at a time when the movable light beam passes through the light-receiving surface of the sensor coincides with a difference between the first output value and the second output value;
- and
- controlling an image forming operation when the control for the angle of the mirror surface of the galvano-mirror has been completed.
An image forming apparatus having an optical scanning device using a galvano-mirror capable of altering an angle of a mirror surface by a drive control, and using a sensor that detects passage positions of a stationary light beam whose scanning position is fixed and a movable light beam whose scanning position is varied by adjusting the angle of the mirror surface of the galvano-mirror, the apparatus comprising:
- first measuring means for effecting, a control to position the movable light beam within a tolerable range of a predetermined first passage target position by adjusting the angle of the mirror surface of the galvano-mirror, and measuring a first circuit offset in a detection circuit for an output of the sensor at a time when emission of the movable light beam is stopped;
- first memory means for emitting the movable light beam once again, effecting a control to position the movable light beam at the first passage target position with the first circuit offset measured by the first measuring means being subtracted, and storing a first output value from the sensor at a time when the movable light beam is controlled and set at the first passage target position;
- second measuring means for effecting a control to position the movable light beam within a tolerable range of a predetermined second passage target position by adjusting the angle of the mirror surface of the galvano-mirror, and measuring a second circuit offset in the detection circuit for the output of the sensor at a time when emission of the movable light beam is stopped;
- second memory means for emitting the movable light beam once again, effecting a control to position the movable light beam at the second passage target position with the second circuit offset measured by the second measuring means being subtracted, and storing a second output value from the sensor at a time when the movable light beam is controlled and set at the second passage target position;
- first control means for controlling the angle of the mirror surface of the galvano-mirror such that a difference between a third output value from the sensor at a time when the stationary light beam passes through the light-receiving surface of the sensor and a fourth output value from the sensor at a time when the movable light beam passes through the light-receiving surface of the sensor coincides with a difference between the first output value and the second output value;
- and
- second control means for controlling an image forming operation when the control for the angle of the mirror surface of the galvano-mirror is completed.
Dependencies are inferred from the claim text.