Optical scanning device and image forming apparatus using the same

An optical scanning device comprising:

• a light source;
• a deflecting surface configured to deflect a light beam output from said light source;
• focusing optics configured to focus the light beam deflected by said deflecting surface on a subject surface to be scanned;
• and
• at least one transparent, parallel flat plate intervening between said deflecting surface and the subject surface,
• wherein the light beam incident to said deflecting surface and an optical axis of said focusing optics are angularly spaced from each other in a plane of polarization,
• wherein when a section in a subscanning direction is seen from a side where the light beam is incident to said deflecting surface, an inclination of said at least one flat plate relative to a plane perpendicular to said light beam is positive when clockwise and is referred to by Θ′,
• wherein a function f(i) is f(i)=1 when i is an even number or f(i)=−1 and f(0)=1 when i is an odd number,
• wherein a direction of polarization of the light beam just after emission from said light source is inclined by an angle of θ relative to a main scanning direction,
• wherein when a clockwise direction as seen from a rear of said light source is positive, the angle θ lies in a range of:
• 0°<θ<45° or −90°<θ<−45° (condition 1)
• or
• −45°<θ<0° or 45°<θ<90° (condition 2),
• wherein when said condition 1 holds and when m reflecting members exist between said light source and said at least one flat plate except for said deflecting surface, said at least one flat plate satisfies a relation of f(m)×Θ>0, and
• wherein when said condition 2 holds, said at least one flat plate satisfies a relation of f(n)×Θ<0, wherein m and n are integers equal to or greater than 1.

An optical scanning device comprising:

• a light source;
• a deflecting surface configured to deflect a light beam output from said light source;
• focusing optics configured to focus the light beam deflected by said deflecting surface on a subject surface to be scanned;
• and
• a plurality of transparent, parallel flat plates intervening between said deflecting surface and the subject surface,
• wherein the light beam incident to said deflecting surface and an optical axis of said focusing optics are angularly spaced from each other in a plane of polarization,
• wherein when a section in a subscanning direction is seen from a side where the light beam is incident to said deflecting surface, an inclination of each of said plurality of flat plates relative to a plane perpendicular to said light beam is positive when clockwise and is referred to by Θ′,
• wherein a function f(i) is f(i)=1 when i is an even number or f(i)=−1 and f(0)=1 when i is an odd number,
• wherein a direction of polarization of the light beam just after emission from said light source is inclined by an angle of θ relative to a main scanning direction,
• wherein when a clockwise direction as seen from a rear of said light source is positive, the angle θ lies in a range of:
• 0°<θ<45° or −90°<θ<−45° (condition 1)
• or
• −45°<θ<0° or 45°<θ<90° (condition 2),
• wherein when said condition 1 holds and when m reflecting members exist between said light source and at least one of said plurality of flat plates except for said deflecting surface, said at least one flat plate satisfies a relation of f(m)×Θ′>0 and has a number of anti-reflection coating layers smaller than, if odd, a mean number of anti-reflection coating layers of another flat plate that satisfies a relation of f(m)×Θ′<0 in a clockwise direction, and
• wherein when said condition 2 holds, the at least one of said plurality of flat plates satisfies the relation of f(m)×Θ′<0 and has a number of anti-reflection coating layers smaller than, if odd, a mean number of anti-reflection layers of another flat plate that satisfies a relation of f(m)×Θ′>0 in the clockwise direction, wherein m is an integer equal to or greater than 1.

An optical scanning device comprising:

• a light source;
• a deflecting surface configured to deflect a light beam output from said light source;
• focusing optics configured to focus the light beam deflected by said deflecting surface on a subject surface to be scanned;
• and
• two transparent, parallel flat plates intervening between said deflecting surface and the subject surface,
• wherein the light beam incident to said deflecting surface and an optical axis of said focusing optics are angularly spaced from each other in a plane of polarization,
• wherein when a section in a subscanning direction is seen from a side where the light beam is incident to said deflecting surface, an inclination of each of said two flat plates relative to a plane perpendicular to said light beam is positive when clockwise and is referred to by Θ′,
• wherein a function f(i) is f(i)=1 when i is an even number or f(i)=−1 and f(0)=1 when i is an odd number,
• wherein a direction of polarization of the light beam just after emission from said light source is inclined by an angle of θ relative to a main scanning direction,
• wherein when a clockwise direction as seen from a rear of said light source is positive, the angle θ lies in a range of:
• 0°<θ<45° or −90°<θ<−45° (condition 1)
• or
• −45°<θ<0° or 45°<θ<90° (condition 2),
• wherein when said condition 1 holds and when m reflecting members exist between said light source and each of said two flat plates except for said deflecting surface, said two flat plates both satisfy a relation of f(m)×Θ′>0 or only one of said two flat plates satisfies said relation of f(m)×Θ′>0 and has a greater absolute value of Θ′ than the other flat plate, and
• wherein when said condition 2 holds, said two flat plates both satisfy a relation of f(m)×Θ′<0 or only one of said two flat plates satisfies said relation of f(m)×Θ′>0 and has a greater absolute value of Θ′ than the other flat plate, wherein m is an integer equal to or greater than 1.

An image forming apparatus comprising:

• an image carrier;
• and
• an optical scanning device configured to scan a surface of said image carrier with a deflected light beam to thereby form a latent image on said surface;
• said optical scanning device comprising:
• a light source;
• a deflecting surface configured to deflect a light beam output from said light source;
• focusing optics configured to focus the light beam deflected by said deflecting surface on the surface of said image carrier;
• and
• at least one reflecting member intervening between said deflecting surface and the surface of said image carrier,
• wherein the light beam incident to said deflecting surface and an optical axis of said focusing optics are angularly spaced from each other in a plane of polarization,
• wherein when a section in a subscanning direction is seen from a side where the light beam is incident to said deflecting surface, an inclination of said at least one reflecting member relative to a plane perpendicular to said light beam is positive when clockwise and is referred to by Θ′,
• wherein a function f(i) is f(i)=1 when i is an even number or f(i)=−1 when i is an odd number,
• wherein a direction of polarization of the light beam just after emission from said light source is inclined by an angle of θ relative to a main scanning direction,
• wherein when a clockwise direction as seen from a rear of said light source is positive, the angle θ lies in a range of:
• 0°<θ<45° or −90°<θ<−45° (condition 1)
• or
• −45°<θ<0° or 45°<θ<90° (condition 2),
• wherein when said condition 1 holds, said at least one reflecting member is an “n” reflecting member, as counted from said light source in a direction of propagation of the light beam, except for said deflecting surface and satisfies a relation of f(n)×Θ>0, and
• wherein when said condition 2 holds, said at least one reflecting member is an “n” reflecting member, as counted from said light source in said direction, except for said deflecting surface and satisfies a relation of f(n)×Θ<0.

An image forming apparatus comprising:

• an image carrier;
• and
• an optical scanning device configured to scan a surface of said image carrier with a deflected light beam to thereby form a latent image on said surface;
• said optical scanning device comprising:
• a light source;
• a deflecting surface configured to deflect a light beam output from said light source;
• focusing optics configured to focus the light beam deflected by said deflecting surface on the surface of said image carrier;
• and
• at least one transparent, parallel flat plate intervening between said deflecting surface and the surface of said image carrier,
• wherein the light beam incident to said deflecting surface and an optical axis of said focusing optics are angularly spaced from each other in a plane of polarization,
• wherein when a section in a subscanning direction is seen from a side where the light beam is incident to said deflecting surface, an inclination of said at least one flat plate relative to a plane perpendicular to said light beam is positive when clockwise and is referred to by Θ′,
• wherein a function f(i) is f(i)=1 when i is an even number or f(i)=−1 and f(0)=1 when i is an odd number,
• wherein a direction of polarization of the light beam just after emission from said light source is inclined by an angle of θ relative to a main scanning direction,
• wherein when a clockwise direction as seen from a rear of said light source is positive, the angle θ lies in a range of:
• 0°<θ<45° or −90°<θ<−45° (condition 1)
• or
• −45°<θ<0° or 45°<θ<90° (condition 2),
• wherein when said condition 1 holds and when m reflecting members exist between said light source and said at least one flat plate except for said deflecting surface, said at least one flat plate satisfies a relation of f(m)×Θ′>0, and
• wherein when said condition 2 holds, said at least one flat plate satisfies a relation of f(n)×Θ′<0, wherein m and n are integers equal to or greater than 1.

An image forming apparatus comprising:

• an image carrier;
• and
• an optical scanning device configured to scan a surface of said image carrier with a deflected light beam to thereby form a latent image on said surface;
• said optical scanning device comprising:
• a light source;
• a deflecting surface configured to deflect a light beam output from said light source;
• focusing optics configured to focus the light beam deflected by said deflecting surface on the surface of said image carrier;
• and
• a plurality of transparent, parallel flat plates intervening between said deflecting surface and the surface of said image carrier,
• wherein the light beam incident to said deflecting surface and an optical axis of said focusing optics are angularly spaced from each other in a plane of polarization,
• wherein when a section in a subscanning direction is seen from a side where the light beam is incident to said deflecting surface, an inclination of each of said plurality of flat plates relative to a plane perpendicular to said light beam is positive when clockwise and is referred to by Θ′,
• wherein a function f(i) is f(i)=1 when i is an even number or f(i)=−1 and f(0)=1 when i is an odd number,
• wherein a direction of polarization of the light beam just after emission from said light source is inclined by an angle of θ relative to a main scanning direction,
• wherein when a clockwise direction as seen from a rear of said light source is positive, the angle θ lies in a range of:
• 0°<θ<45° or −90°<θ<−45° (condition 1)
• or
• −45°<θ<0° or 45°<θ<90° (condition 2),
• wherein when said condition 1 holds and when m reflecting members exist between said light source and at least one of said plurality of flat plates except for said deflecting surface, said at least one flat plate satisfies a relation f(m)×Θ′>0 and has a number of anti-reflection coating layers smaller than, if odd, a mean number of anti-reflection coating layers of another flat plate that satisfies a relation of f(m)×Θ′<0 in a clockwise direction, and
• wherein when said condition 2 holds, at least one of said plurality of flat plates satisfies the relation of f(m)×Θ′<0 and has a number of anti-reflection coating layers smaller than, if odd, a mean number of anti-reflection coating layers of another flat plate that satisfies the relation of f(m)×Θ′>0 in the clockwise direction, wherein m is an integer equal to or greater than 1.

An image forming apparatus comprising:

• an image carrier;
• and
• an optical scanning device configured to scan a surface of said image carrier with a deflected light beam to thereby form a latent image on said surface;
• said optical scanning device comprising:
• a light source;
• a deflecting surface configured to deflect a light beam output from said light source;
• focusing optics configured to focus the light beam deflected by said deflecting surface on the surface of said image carrier;
• and
• two transparent, parallel flat plates intervening between said deflecting surface and the surface of said image carrier,
• wherein the light beam incident to said deflecting surface and an optical axis of said focusing optics are angularly spaced from each other in a plane of polarization,
• wherein when a section in a subscanning direction is seen from a side where the light beam is incident to said deflecting surface, an inclination of each of said two flat plates relative to a plane perpendicular to said light beam is positive when clockwise and is referred to by Θ′,
• wherein a function f(i) is f(i)=1 when i is an even number or f(i)=−1 and f(0)=1 when i is an odd number,
• wherein a direction of polarization of the light beam just after emission from said light source is inclined by an angle of θ relative to a main scanning direction,
• wherein when a clockwise direction as seen from a rear of said light source is positive, the angle θ lies in a range of:
• 0°<θ<45° or −90°<θ<−45° (condition 1)
• or
• −45°<θ<0° or 45°<θ<90° (condition 2),
• wherein when said condition 1 holds and when m reflecting members exist between said light source and each of said two flat plates except for said deflecting surface, said two flat plates both satisfy a relation of f(m)×Θ′>0 or only one of said two flat plates satisfies said relation of f(m)×Θ′>0 and has a greater absolute value of Θ′ than the other flat plate, and
• wherein when said condition 2 holds, said two flat plates both satisfy a relation of f(m)×Θ′<0 or only one of said two flat plates satisfies said relation of f(m)×Θ′<0 and has a greater absolute value of Θ′ than the other flat plate, wherein m is an integer equal to or greater than 1.