Optical scanning device and image forming system including the same

An optical scanning device comprising:

• light source means for emitting a light beam based on a pixel clock;
• scanning optical system means for scanning an image surface in a main scanning direction by focusing a deflected light beam, derived from the light beam of the light source means, onto the image surface as a beam spot, the scanning optical system means providing an amount of linearity at an outer peripheral end of the image surface;
• optical writing means for controlling an ON/OFF state of the light source means in accordance with an image signal;
• frequency dividing means, connected to the optical writing means, for generating a secondary frequency of the pixel clock at an output thereof, which is equal to an initial frequency of the pixel clock at an input thereof divided by a divisor integer;
• and
• electrical correction means for adjusting the secondary frequency of the pixel clock at the output of the frequency dividing means with respect to each of respective pixels included in the image signal while the amount of linearity remaining at the outer peripheral end of the image surface is provided by the scanning optical system, when the beam spot is located near the outer peripheral end of the image surface, so as to obtain uniform-velocity characteristics,
• wherein the scanning optical system means is configured to satisfy the conditions 0.5% ≦|Lin|≦10% where Lin indicates the amount of the linearity, and
• the scanning optical system means includes a scanning lens device having lens surfaces that are concentric with respect to a reflection point of a rotary deflector, and the number of the concentric lens surfaces in the scanning lens device is either equal to or larger than the number of non-concentric lens surfaces in the scanning lens device.

An image forming system in which an optical scanning device and an image forming device are provided, the image forming device forming a latent image on an image surface of a photoconductor by using a beam spot created by the optical scanning device, the optical scanning device comprising:

• a light source configured to emit a light beam based on a pixel clock;
• a scanning optical system configured to scan the image surface in a main scanning direction by focusing a deflected light beam, derived from the light beam of the light source, onto the image surface as the beam spot, the scanning optical system configured to provide an amount of linearity at an outer peripheral end of the image surface;
• an optical writing unit configured to control an ON/OFF state of the light source in accordance with an image signal;
• a frequency dividing unit connected to the optical writing unit configured to generate a secondary frequency of the pixel clock at an output thereof, which is equal to an initial frequency of the pixel clock at an input thereof divided by a divisor integer;
• and
• an electrical correction unit configured to adjust the secondary frequency of the pixel clock at the output of the frequency dividing unit with respect to each of respective pixels included in the image signal while the amount of linearity remaining at the outer peripheral end of the image surface is provided by the scanning optical system, when the beam spot is located near the outer peripheral end of the image surface, so as to obtain uniform-velocity characteristics,
• wherein the scanning optical system is configured to satisfy the conditions 0.5% ≦|Lin|≦10% where Lin indicates the amount of the linearity, and
• the scanning optical system includes a scanning lens device having lens surfaces that are concentric with respect to a reflection point of a rotary deflector, and the number of the concentric lens surfaces in the scanning lens device is either equal to or larger than the number of non-concentric lens surfaces in the scanning lens device.

An optical scanning device comprising:

• a light source configured to emit a light beam based on a pixel clock;
• a scanning optical system configured to scan an image surface in a main scanning direction by focusing a deflected light beam, derived from the light beam of the light source, onto the image surface as a beam spot, the scanning optical system configured to provide a maximum amount of linearity Lm over the entire image surface at a maximum-linearity point of the image surface and an amount of linearity Le at an outer peripheral end of the image surface, the scanning optical system being configured to satisfy the condition |Lm/Le|>1.0;
• an optical writing unit configured to control an ON/OFF state of the light source in accordance with an image signal;
• a frequency dividing unit, connected to the optical writing unit, configured to generate a secondary frequency of the pixel clock at an output thereof, which is equal to an initial frequency of the pixel clock at an input thereof divided by a divisor integer;
• and
• an electrical correction unit configured to adjust the secondary frequency of the pixel clock at the output of the frequency dividing unit with respect to each of respective pixels included in the image signal while the amount of linearity remaining at the outer peripheral end of the image surface is provided by the scanning optical system, when the beam spot is located near one of the maximum-linearity point and the outer peripheral end of the image surface, so as to obtain uniform-velocity characteristics,
• wherein the scanning optical system is configured to satisfy the conditions 0.5% ≦|Lin|≦10% where Lin indicates the amount of the linearity, and
• the scanning optical system includes a scanning lens device having lens surfaces that are concentric with respect to a reflection point of a rotary deflector, and the number of the concentric lens surfaces in the scanning lens device is either equal to or larger than the number of non-concentric lens surfaces in the scanning lens device.

An optical scanning device comprising:

• light source means for emitting a light beam based on a pixel clock;
• scanning optical system means for scanning an image surface in a main scanning direction by focusing a deflected light beam, derived from the light beam of the light source means, onto the image surface as a beam spot, the scanning optical system means providing a maximum amount of linearity Lm over the entire image surface at a maximum-linearity point and an amount of linearity Le at an outer peripheral end of the image surface, the scanning optical system means being configured to satisfy the condition |Lm/Le|>1.0;
• optical writing means for controlling an ON/OFF state of the light source means in accordance with an image signal;
• frequency dividing means, connected to the optical writing means, for generating a secondary frequency of the pixel clock at an output thereof, which is equal to an initial frequency of the pixel clock at an input thereof divided by a divisor integer;
• and
• electrical correction means for adjusting the secondary frequency of the pixel clock at the output of the frequency dividing means with respect to each of respective pixels included in the image signal while the amount of linearity remaining at the outer peripheral end of the image surface is provided by the scanning optical system, when the beam spot is located near one of the maximum-linearity point and the outer peripheral end of the image surface, so as to obtain uniform-velocity characteristics,
• wherein the scanning optical system means is configured to satisfy the conditions 0.5% ≦|Lin|≦10% where Lin indicates the amount of the linearity, and
• the scanning optical system means includes a scanning lens device having lens surfaces that are concentric with respect to a reflection point of a rotary deflector, and the number of the concentric lens surfaces in the scanning lens device is either equal to or larger than the number of non-concentric lens surfaces in the scanning lens device.

An image forming system in which an optical scanning device and an image forming device are provided, the image forming device forming a latent image on an image surface of a photoconductor by using a beam spot created by the optical scanning device, the optical scanning device comprising:

• a light source configured to emit a light beam based on a pixel clock;
• a scanning optical system configured to scan an image surface in a main scanning direction by focusing a deflected light beam, derived from the light beam of the light source, onto the image surface as a beam spot, the scanning optical system configured to provide a maximum amount of linearity Lm over the entire image surface at a maximum-linearity point and an amount of linearity Le at an outer peripheral end of the image surface, the scanning optical system being configured to satisfy the condition |Lm/Le|>1.0;
• an optical writing unit configured to control an ON/OFF state of the light source in accordance with an image signal;
• a frequency dividing unit, connected to the optical writing unit, configured to generate a secondary frequency of the pixel clock at an output thereof, which is equal to an initial frequency of the pixel clock at an input thereof divided by a divisor integer;
• and
• an electrical correction unit configured to adjust the secondary frequency of the pixel clock at the output of the frequency dividing unit with respect to each of respective pixels included in the image signal while the amount of linearity remaining at the outer peripheral end of the image surface is provided by the scanning optical system, when the beam spot is located near one of the maximum-linearity point and the outer peripheral end of the image surface, so as to obtain uniform-velocity characteristics,
• wherein the scanning optical system is configured to satisfy the conditions 0.5% ≦|Lin|≦10% where Lin indicates the amount of the linearity, and
• the scanning optical system includes a scanning lens device having lens surfaces that are concentric with respect to a reflection point of a rotary deflector, and the number of the concentric lens surfaces in the scanning lens device is either equal to or larger than the number of non-concentric lens surfaces in the scanning lens device.