US 8,998,372 B2Granted

Scanning optical apparatus and image forming apparatus

AssigneeKYOCERA Document Solutions Inc.

InventorShingo Yoshida

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Abstract

A scanning optical apparatus includes a light beam detection unit, a reference signal generation unit, and a returned light detection unit. The light beam detection unit decides whether the light beam reflected by the reflecting surface of a polygon mirror has entered the BD sensor, through comparison between an output value of the BD sensor and a predetermined first threshold. The reference signal generation unit generates a scan start reference signal in response to the decision that the light beam has entered the BD sensor. The returned light detection unit decides whether the light beam reflected by the reflecting surface has entered the internal light sensor, through comparison between an output value of the internal light sensor and a second threshold corresponding to light beam intensity higher than the intensity of the light beam reflected by the reflecting surface and corresponding to the first threshold.

Claims6

Dependent claims

A scanning optical apparatus comprising:

a light source;
a polygon mirror including a plurality of reflecting surfaces that reflect a light beam emitted from the light source, and configured to move the reflecting surfaces to deflect the light beam emitted from the light source, so as to scan a surface to be scanned in a main scanning direction;
a first sensor that receives the light beam reflected by the reflecting surfaces of the polygon mirror;
a second sensor located inside the light source so as to intersect the optical axis of the light beam at a position opposite to an emission outlet of the light beam, the second sensor being receives the light beam reflected by the reflecting surface and detects intensity of the light beam received;
a light beam detection unit that compares between an output value of the first sensor and a predetermined first threshold, to thereby decide that the light beam reflected by the reflecting surface has entered the first sensor when the output value of the first sensor is equal to or higher than the first threshold, and that the light beam reflected by the reflecting surface has not entered the first sensor when the output value of the first sensor is lower than the first threshold;
a reference signal generation unit that generates a scan start reference signal for starting scanning of the surface to be scanned with the light beam deflected by the reflecting surface, when the light beam detection unit detects that the light beam has entered the first sensor;
and
a returned light detection unit that compares between an output value of the second sensor and a second threshold corresponding to light beam intensity higher than the intensity of the light beam reflected by the reflecting surface and corresponding to the first threshold, to thereby decide that the light beam reflected by the reflecting surface has entered the second sensor when the output value of the second sensor is equal to or higher than the second threshold, and that the light beam reflected by the reflecting surface has not entered the second sensor when the output value of the second sensor is lower than the second threshold.

5 more elements

An image forming apparatus comprising:

a scanning optical apparatus;
an image carrier that carries a toner image to be transferred to a medium;
a charger that electrically charges an image carrying surface of the image carrier;
and
a developing unit that applies a toner to a static latent image formed by exposure of the image carrying surface performed by the scanning optical apparatus, thereby forming a toner image based on the latent image on the image carrying surface,
wherein the scanning optical apparatus includes:
a light source;
a polygon mirror including a plurality of reflecting surfaces that reflect a light beam emitted from the light source, and configured to move the reflecting surfaces to deflect the light beam emitted from the light source, so as to scan a surface to be scanned in a main scanning direction;
a first sensor that receives the light beam reflected by the reflecting surfaces of the polygon mirror;
a second sensor that receives the light beam reflected by the reflecting surface and detects intensity of the light beam received, the second sensor being located inside the light source so as to intersect the optical axis of the light beam at a position opposite to an emission outlet of the light beam;
a light beam detection unit that compares between an output value of the first sensor and a predetermined first threshold, to thereby decide that the light beam reflected by the reflecting surface has entered the first sensor when the output value of the first sensor is equal to or higher than the first threshold, and that the light beam reflected by the reflecting surface has not entered the first sensor when the output value of the first sensor is lower than the first threshold;
a reference signal generation unit that generates a scan start reference signal for starting scanning of the surface to be scanned with the light beam deflected by the reflecting surface, when the light beam detection unit detects that the light beam has entered the first sensor;
and
a returned light detection unit that compares between an output value of the second sensor and a second threshold corresponding to light beam intensity higher than the intensity of the light beam reflected by the reflecting surface and corresponding to the first threshold, to thereby decide that the light beam reflected by the reflecting surface has entered the second sensor when the output value of the second sensor is equal to or higher than the second threshold, and that the light beam reflected by the reflecting surface has not entered the second sensor when the output value of the second sensor is lower than the second threshold.

11 more elements

Dependencies are inferred from the claim text.