Optical scanning device, optical scanning method, and image forming apparatus

An optical scanning device which divides an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction thereof, comprising:

• n light sources respectively corresponding to said n partial scanning portions and configured to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas;
• at least one deflecting device configured to deflect the respective light fluxes;
• and
• at least one scanning imaging optical device configured to converge light fluxes deflected by said deflecting device toward said surface to be scanned, such that each light flux from said light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions,
• wherein a line width Li and a line concentration Di, where i=1 though n, of one-dot lines formed by scanning with a light flux near a center portion of an ith partial scanning portion of said n partial scanning portions is determined by a first optical scanning condition set such that an average value Ave{(Li)×Di{circumflex over ( )}(⅕)}, a maximum value Max{(Li)×Di{circumflex over ( )}(⅕)}, and a minimum value Min {(Li)×Di{circumflex over ( )}(⅕)}, of computation values (Li)×Di{circumflex over ( )}(⅕) of said one-dot lines satisfy a first condition of:
• Max{(Li)×Di{circumflex over ( )}(⅕)}/1.15<Ave{(Li)×Di{circumflex over ( )}(⅕)}<Min{(Li)×Di{circumflex over ( )}(⅕)}/0.85.

An optical scanning device which divides an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction thereof, comprising:

• n light sources respectively corresponding to said n partial scanning portions and configured to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas;
• at least one deflecting device configured to deflect the respective light fluxes;
• and
• at least one scanning imaging optical device configured to converge light fluxes deflected by said deflecting device toward said surface to be scanned, such that each light flux from said light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions,
• wherein a first line width ratio Li/Li+1, where i=1 through n−1, of one-dot lines formed by scanning with a light flux elongated in a sub-scanning direction near a seam between an ith partial scanning portion and an i+1th partial scanning portion, denoted as a sub-scanning line width ratio KS, is determined by a first optical scanning condition set such that the sub-scanning line width ratio KS satisfies a first ratio condition of:
• 0.9<KS<1.1.

An optical scanning device which divides an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction thereof, comprising:

• n light sources respectively corresponding to said n partial scanning portions and configured to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas;
• at least one deflecting device configured to deflect the respective light fluxes;
• and
• at least one scanning imaging optical device configured to converge light fluxes deflected by said deflecting device toward said surface to be scanned, such that each light flux from said light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions,
• wherein a line width ratio Li/Li+1, where i=1 through n−1, of one-dot lines formed by scanning with a light flux elongated in a main scanning direction near a seam between an ith partial scanning portion and an i+1th partial scanning portion, denoted as a main scanning line width ratio KM, is determined by an optical scanning condition set such that the main scanning line width ratio KM satisfies a ratio condition of:
• 0.93<KM<1.07.

An optical scanning device which divides an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction thereof, comprising:

• n light sources respectively corresponding to said n partial scanning portions and configured to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas;
• at least one deflecting device configured to deflect the respective light fluxes;
• and
• at least one scanning imaging optical device configured to converge light fluxes deflected by said deflecting device toward said surface to be scanned, such that each light flux from said light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions,
• wherein a first line width ratio Li/Li+1, where i=1 through n−1, of one-dot lines formed by scanning with a light flux elongated in a sub-scanning direction near a seam between an ith partial scanning portion and an i+1th partial scanning portion, denoted as a sub-scanning line width ratio KS, and a first line concentration ratio Di/Di+1, denoted as a line concentration ratio HS, are determined by a first optical scanning condition set such that a computation amount (KS)×HS{circumflex over ( )}(⅕) of said one-dot lines satisfies a first condition of:
• 0.9<(KS)×HS{circumflex over ( )}(⅕)<1.1.

An optical scanning device which divides an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction thereof, comprising:

• n light sources respectively corresponding to said n partial scanning portions and configured to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas;
• at least one deflecting device configured to deflect the respective light fluxes;
• and
• at least one scanning imaging optical device configured to converge light fluxes deflected by said deflecting device toward said surface to be scanned, such that each light flux from said light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions,
• wherein a line width ratio Li/Li+1, where i=1 through n−1, of one-dot lines formed by scanning with a light flux elongated in a main scanning direction near a seam between an ith partial scanning portion and an i+1th partial scanning portion, denoted as a main scanning line width ratio KM, and a line concentration ratio Di/Di+1, denoted as a line concentration ratio HM, are determined by an optical scanning condition set such that a computation amount (KM)×HM{circumflex over ( )}(⅕) of said one-dot lines satisfies a condition of:
• 0.93<(KM)×HM{circumflex over ( )}(⅕)<1.07.

An image forming apparatus, comprising:

• a photosensitive member configured to form a latent image thereupon;
• an optical scanning device configured to optically scan the photosensitive member to form the latent image;
• and
• a developing device configured to develop the latent image into a toner image and to thereby obtain an image;
• wherein the optical scanning device divides an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction thereof, and includes n light sources respectively corresponding to said n partial scanning portions and configured to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas, said optical scanning device, further comprising:
• at least one deflecting device configured to deflect the respective light fluxes;
• and
• at least one scanning imaging optical device configured to converge light fluxes deflected by said deflecting device toward said surface to be scanned, such that each light flux from said light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions,
• wherein a line width Li, where i=1 through n, of one-dot lines formed by scanning with a light flux near a center portion of an ith partial scanning portion of said n partial scanning portions is determined by an optical scanning condition set such that an average value Ave(Li), a maximum value Max(Li), and a minimum value Min (Li), of the line width Li of said one-dot lines satisfy a line width condition of:
• Max(Li)/1.15<Ave(Li)<Min(Li)/0.85.

An image forming apparatus, comprising:

• a photosensitive member configured to form a latent image thereupon;
• an optical scanning device configured to optically scan the photosensitive member to form the latent image;
• and
• a developing device configured to develop the latent image into a toner image and to thereby obtain an image;
• wherein the optical scanning device divides an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction thereof, and includes n light sources respectively corresponding to said n partial scanning portions and configured to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas, said optical scanning device, further comprising:
• at least one deflecting device configured to deflect the respective light fluxes;
• and
• at least one scanning imaging optical device configured to converge light fluxes deflected by said deflecting device toward said surface to be scanned, such that each light flux from said light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions,
• wherein a line width and a line concentration Li, where=i=1 through n, of one-dot lines formed by scanning with a light flux near a center portion of an ith partial scanning portion of said n partial scanning portions are determined by a first optical scanning condition set such that an average value Ave{(Li)×Di{circumflex over ( )}(⅕)}, a maximum value Max{(Li)×Di{circumflex over ( )}(⅕)}, and a minimum value Min {(Li)×Di{circumflex over ( )}(⅕)}, of computation values (Li)×Di{circumflex over ( )}(⅕) of said one-dot lines satisfy a first condition of:
• Max{(Li)×Di{circumflex over ( )}(⅕)}/1.15<Ave{(Li)×Di{circumflex over ( )}(⅕)}<Min{(Li)×Di{circumflex over ( )}(⅕)}/0.85.

An image forming apparatus, comprising:

• a photosensitive member configured to form a latent image thereupon;
• an optical scanning device configured to optically scan the photosensitive member to form the latent image;
• and
• a developing device configured to develop the latent image into a toner image and to thereby obtain an image;
• wherein the optical scanning device divides an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction thereof, and includes n light sources respectively corresponding to said n partial scanning portions and configured to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas, said optical scanning device, further comprising:
• at least one deflecting device configured to deflect the respective light fluxes;
• and
• at least one scanning imaging optical device configured to converge light fluxes deflected by said deflecting device toward said surface to be scanned, such that each light flux from said light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions,
• wherein a line width ratio Li/Li+1,where i=1 through n−1, of one-dot lines formed by scanning with a light flux elongated in a sub-scanning direction near a seam between an ith partial scanning portion and an i+1th partial scanning portion, denoted as a sub-scanning line width ratio KS, is determined by a first optical scanning condition set such that the sub-scanning line width ratio KS satisfies a first ratio condition of:
• 0.9<KS<1.1.

An image forming apparatus, comprising:

• a photosensitive member configured to form a latent image thereupon;
• an optical scanning device configured to optically scan the photosensitive member to form the latent image;
• and
• a developing device configured to develop the latent image into a toner image and to thereby obtain an image;
• wherein the optical scanning device divides an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction thereof, and includes n light sources respectively corresponding to said n partial scanning portions and configured to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas, said optical scanning device, further comprising:
• at least one deflecting device configured to deflect the respective light fluxes;
• and
• at least one scanning imaging optical device configured to converge light fluxes deflected by said deflecting device toward said surface to be scanned, such that each light flux from said light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions,
• wherein a line width ratio Li/Li+1, where i=1 through n−1, of one-dot lines formed by scanning with a light flux elongated in a main scanning direction near a seam between an ith partial scanning portion and an i+1th partial scanning portion, denoted as a main scanning line width ratio KM, is determined by an optical scanning condition set such that the main scanning line width ratio KM satisfies a ratio condition of:
• 0.9<KM<1.07.

An image forming apparatus, comprising:

• a photosensitive member configured to form a latent image thereupon;
• an optical scanning device configured to optically scan the photosensitive member to form the latent image;
• and
• a developing device configured to develop the latent image into a toner image and to thereby obtain an image;
• wherein the optical scanning device divides an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction thereof, and includes n light sources respectively corresponding to said n partial scanning portions and configured to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas, said optical scanning device, further comprising:
• at least one deflecting device configured to deflect the respective light fluxes;
• and
• at least one scanning imaging optical device configured to converge light fluxes deflected by said deflecting device toward said surface to be scanned, such that each light flux from said light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions,
• wherein a first line width ratio Li/Li+1, where i=1 through n−1, of one-dot lines formed by scanning with a light flux elongated in a sub-scanning direction near a seam between an ith partial scanning portion and an i+1th partial scanning portion, denoted as a sub-scanning line width ratio KS, and a first line concentration ratio Di/Di+1, denoted as a line concentration ratio HS, are determined by a first optical scanning condition set such that a computation amount (KS)×HS{circumflex over ( )}(⅕) of said one-dot lines satisfies a first condition of:
• 0.9<(KS)×HS{circumflex over ( )}(⅕)<1.1.

An image forming apparatus, comprising:

• a photosensitive member configured to form a latent image thereupon;
• an optical scanning device configured to optically scan the photosensitive member to form the latent image;
• and
• a developing device configured to develop the latent image into a toner image and to thereby obtain an image;
• wherein the optical scanning device divides an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction thereof, and includes n light sources respectively corresponding to said n partial scanning portions and configured to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas, said optical scanning device, further comprising:
• at least one deflecting device configured to deflect the respective light fluxes;
• and
• at least one scanning imaging optical device configured to converge light fluxes deflected by said deflecting device toward said surface to be scanned, such that each light flux from said light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions,
• wherein a line width ratio Li/Li+1, where i=1 through n−1, of one-dot lines formed by scanning with a light flux elongated in a main scanning direction near a seam between an ith partial scanning portion and an i+1th partial scanning portion, denoted as a main scanning line width ratio KM, and a line concentration ratio Di/Di+1, denoted as a line concentration ratio HM, are defined by an optical scanning condition set such that a computation amount (KM)×HM{circumflex over ( )}(⅕) of said one-dot lines satisfies a condition of:
• 0.93<(KM)×HM{circumflex over ( )}(⅕)<1.07.

An optical scanning device which divides an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction thereof, comprising:

• n light sources respectively corresponding to said n partial scanning portions and configured to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas;
• deflecting means for deflecting the respective light fluxes;
• and
• optical means for converging the light fluxes deflected by said deflecting means toward said surface to be scanned, such that each light flux from said light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions,
• wherein a line width Li, where i=1 through n, lines formed by scanning with a light flux near a center portion of an ith partial scanning portion of said n partial scanning portions is determined by an optical scanning condition set such that an average value Ave(Li), a maximum value Max(Li), and a minimum value Min (Li), of line widths Li of said one-dot lines satisfy a line width condition of:
• Max(Li)/1.15<Ave(Li)<Min(Li)/0.85.

An optical scanning device which divides an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction thereof, comprising:

• n light sources respectively corresponding to said n partial scanning portions and configured to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas;
• deflecting means for deflecting the respective light fluxes;
• and
• optical means for converging the light fluxes deflected by said deflecting means toward said surface to be scanned, such that each light flux from said light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions,
• wherein a line width Li, where i=1 through n, and a line concentration Di of one-dot lines formed by scanning with a corresponding light flux near a center portion of an i partial scanning portion of said n partial scanning portions are determined by an optical scanning condition set such that an average value Ave{(Li)×Di{circumflex over ( )}(⅕)}, a maximum value Max{(Li)×Di{circumflex over ( )}(⅕)}, and a minimum value Min {(Li)×Di{circumflex over ( )}(⅕)}, of computation values (Li)×Di{circumflex over ( )}(⅕) of said one-dot lines satisfy a first condition of:
• Max{(Li)×Di{circumflex over ( )}(⅕)}/1.15<Ave{(Li)×Di{circumflex over ( )}(⅕)}<Min{(Li)×Di{circumflex over ( )}(⅕)}/0.85.

An optical scanning device which divides an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction thereof, comprising:

• n light sources respectively corresponding to said n partial scanning portions and configured to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas;
• deflecting means for deflecting the respective light fluxes;
• and
• optical means for converging the light fluxes deflected by said deflecting means toward said surface to be scanned, such that each light flux from said light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions,
• wherein a line width ratio Li/Li+1, where i=1 through n−1, of one-dot lines formed by scanning with a light flux elongated in a sub-scanning direction near a seam between an ith partial scanning portion and an i+1th partial scanning portion, denoted as a sub-scanning line width ratio KS, is determined by an optical scanning condition set such that the sub-scanning line width ratio KS satisfies a ratio condition of:
• 0.9<KS<1.1.

An optical scanning device which divides an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction thereof, comprising:

• n light sources respectively corresponding to said n partial scanning portions and configured to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas;
• deflecting means for deflecting the respective light fluxes;
• and
• optical means for converging the light fluxes deflected by said deflecting means toward said surface to be scanned, such that each light flux from said light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions,
• wherein a line width ratio Li/Li+1, where i=1 through n−1, of one-dot lines formed by scanning with a light flux elongated in a main scanning direction near a seam between an ith partial scanning portion and an i+1th partial scanning portion, denoted as a main scanning line width ratio KM, is determined by an optical scanning condition set such that the main scanning line width ratio KM satisfies a ratio condition of:
• 0.93<KM<1.07.

An optical scanning device which divides an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction thereof, comprising:

• n light sources respectively corresponding to said n partial scanning portions and configured to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas;
• deflecting means for deflecting the respective light fluxes;
• and
• optical means for converging the light fluxes deflected by said deflecting means toward said surface to be scanned, such that each light flux from said light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions,
• wherein a line width ratio Li/Li+1, where i=1 through n−1 of one-dot lines formed by scanning with a light flux elongated in a sub-scanning direction near a seam between an ith partial scanning portion and an i+1th partial scanning portion, denoted as a sub-scanning line width ratio KS, and a line concentration ratio Di/Di+1, denoted as a line concentration ratio HS, and are defined by an optical scanning condition set such that a computation amount (KS)×HS{circumflex over ( )}(⅕) of said one-dot lines satisfies a condition of:
• 0.9<(KS)×HS{circumflex over ( )}(⅕)<1.1.

An optical scanning device which divides an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction thereof, comprising:

• n light sources respectively corresponding to said n partial scanning portions and configured to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas;
• deflecting means for deflecting the respective light fluxes;
• and
• optical means for converging the light fluxes deflected by said deflecting means toward said surface to be scanned, such that each light flux from said light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions,
• wherein a line width ratio Li/Li+1, where i=1 through n−1, of one-dot lines formed by scanning with a light flux elongated in a main scanning direction near a seam between an ith partial scanning portion and an i+1th partial scanning portion, denoted as a main scanning line width ratio KM, and a line concentration ratio Di/Di+1, denoted as a line concentration ratio HM, are defined by an optical scanning condition set such that a computation amount (KM)×HM{circumflex over ( )}(⅕) of said one-dot lines satisfies a condition of:
• 0.93<(KM)×HM{circumflex over ( )}(⅕)<1.07.

An image forming apparatus, comprising:

• a photosensitive member configured to form a latent image thereupon;
• an optical scanning device configured to optically scan the photosensitive member to form the latent image;
• and
• developing means for developing the latent image into a toner image and to thereby obtain an image;
• wherein the optical scanning device is configured to divide an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction and includes n light sources respectively corresponding to said n partial scanning portions and configured to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas, said optical scanning device further comprising:
• deflecting means for deflecting the respective light fluxes;
• and
• optical means for converging light fluxes deflected by said deflecting means toward said surface to be scanned, such that each light flux from the light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions,
• wherein a line width Li, where i=1 through n, of one-dot lines formed by scanning with a light flux near a center portion of an ith partial scanning portion of said n partial scanning portions is determined by an optical scanning condition set such that an average value Ave(Li), a maximum value Max(Li), and a minimum value Min (Li), of line widths Li of said one-dot lines satisfy a condition of:
• Max(Li)/1.15<Ave(Li)<Min(Li)/0.85.

An image forming apparatus, comprising:

• a photosensitive member configured to form a latent image thereupon;
• an optical scanning device configured to optically scan the photosensitive member to form the latent image;
• and
• developing means for developing the latent image into a toner image and to thereby obtain an image;
• wherein the optical scanning device is configured to divide an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction and includes n light sources respectively corresponding to said n partial scanning portions and configured to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas, said optical scanning device further comprising:
• deflecting means for deflecting the respective light fluxes;
• and
• optical means for converging light fluxes deflected by said deflecting means toward said surface to be scanned, such that each light flux from the light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions,
• wherein a line width Li, where i=1 through n, and a line concentration Di of one-dot lines formed by scanning with a light flux near a center portion of an ith partial scanning portion of said n partial scanning portions are determined by an optical scanning condition set such that an average value Ave{(Li)×Di{circumflex over ( )}(⅕)}, a maximum value Max{(Li)×Di{circumflex over ( )}(⅕)}, and a minimum value Min {(Li)×Di{circumflex over ( )}(⅕)}, of computation values (Li)×Di{circumflex over ( )}(⅕) of said one-dot lines satisfy a condition of:
• Max{(Li)×Di{circumflex over ( )}(⅕)}/1.15<Ave{(Li)×Di{circumflex over ( )}(⅕)}<Min{(Li)×Di{circumflex over ( )}(⅕)}/0.85.

An image forming apparatus, comprising:

• a photosensitive member configured to form a latent image thereupon;
• an optical scanning device configured to optically scan the photosensitive member to form the latent image;
• and
• developing means for developing the latent image into a toner image and to thereby obtain an image;
• wherein the optical scanning device is configured to divide an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction and includes n light sources respectively corresponding to said n partial scanning portions and configured to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas, said optical scanning device further comprising:
• deflecting means for deflecting the respective light fluxes;
• and
• optical means for converging light fluxes deflected by said deflecting means toward said surface to be scanned, such that each light flux from the light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions,
• wherein a line width ratio Li/Li+1, where i=1 through n−1, of one-dot lines formed by scanning with a light flux elongated in a sub-scanning direction near a seam between an ith partial scanning portion and an i+1th partial scanning portion, denoted as a sub-scanning line width ratio KS, is determined by an optical scanning condition set such that the sub-scanning line width ratio KS satisfies a condition of:
• 0.9<KS<1.1.

An image forming apparatus, comprising:

• a photosensitive member configured to form a latent image thereupon;
• an optical scanning device configured to optically scan the photosensitive member to form the latent image;
• and
• developing means for developing the latent image into a toner image and to thereby obtain an image;
• wherein the optical scanning device is configured to divide an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction and includes n light sources respectively corresponding to said n partial scanning portions and configured to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas, said optical scanning device further comprising:
• deflecting means for deflecting the respective light fluxes;
• and
• optical means for converging light fluxes deflected by said deflecting means toward said surface to be scanned, such that each light flux from the light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions,
• wherein a line width ratio Li/Li+1, where i=1 through n−1, of one-dot lines formed by scanning with a corresponding light flux long in a main scanning direction near a seam between an ith partial scanning portion and an i+1th partial scanning portion, denoted as a main scanning line width ratio KM, is determined by an optical scanning condition set such that the main scanning line width ratio KM satisfies a condition of:
• 0.93<KM<1.07.

An image forming apparatus, comprising:

• a photosensitive member configured to form a latent image thereupon;
• an optical scanning device configured to optically scan the photosensitive member to form the latent image;
• and
• developing means for developing the latent image into a toner image and to thereby obtain an image;
• wherein the optical scanning device is configured to divide an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction and includes n light sources respectively corresponding to said n partial scanning portions and configured to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas, said optical scanning device further comprising:
• deflecting means for deflecting the respective light fluxes;
• and
• optical means for converging light fluxes deflected by said deflecting means toward said surface to be scanned, such that each light flux from the light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions,
• wherein a line width ratio Li/Li+1, where i=1 through n−1, of one-dot lines formed by scanning with a light flux elongated in a sub-scanning direction near a seam between an ith partial scanning portion and an i+1th partial scanning portion, denoted as a sub-scanning line width ratio KS, and a line concentration ratio Di/Di+1, denoted as a line concentration ratio HS, are determined by an optical scanning condition set such that a computation amount (KS)×HS{circumflex over ( )}(⅕) of said one-dot lines satisfies a condition of:
• 0.9<(KS)×HS{circumflex over ( )}(⅕)<1.1.

An image forming apparatus, comprising:

• a photosensitive member configured to form a latent image thereupon;
• an optical scanning device configured to optically scan the photosensitive member to form the latent image;
• and
• developing means for developing the latent image into a toner image and to thereby obtain an image;
• wherein the optical scanning device is configured to divide an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction and includes n light sources respectively corresponding to said n partial scanning portions and configured to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas, said optical scanning device further comprising:
• deflecting means for deflecting the respective light fluxes;
• and
• optical means for converging light fluxes deflected by said deflecting means toward said surface to be scanned, such that each light flux from the light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions,
• wherein a line width ratio Li/Li+1, where i=1 through n−1, of one-dot lines formed by scanning with a light flux elongated in a main scanning direction near a seam between an ith partial scanning portion and an i+1th partial scanning portion, denoted as a main scanning line width ratio KM, and a line concentration ratio Di/Di+1, denoted as a line concentration ratio HM, are determined by an optical scanning condition set such that a computation amount (KM)×HM{circumflex over ( )}(⅕) of said one-dot lines satisfies a condition of:
• 0.93<(KM)×HM{circumflex over ( )}(⅕)<1.07.

An optical scanning method which divides an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction thereof and which uses n light sources respectively corresponding to said n partial scanning portions to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas, the method comprising:

• deflecting the respective light fluxes from said n light sources with a deflecting device;
• converging light fluxes deflected by said deflecting device toward said surface to be scanned with a scan imaging optical device, such that each light flux from the light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions;
• forming one-dot lines on each partial scanning portion of said n partial scanning portions by scanning with one of said respective light fluxes;
• and
• with a line width Li, where i=1 through n, of said one-dot lines formed by scanning with a light flux near a center portion of an ith partial scanning portion of said n partial scanning portions, setting an optical scanning condition such that an average value Ave(Li), a maximum value Max(Li), and a minimum value Min (Li), of line widths Li of said one-dot lines satisfy a line width condition of:
• Max(Li)/1.15<Ave(Li)<Min(Li)/0.85.

An optical scanning method which divides an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction thereof and which uses n light sources respectively corresponding to said n partial scanning portions to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas, the method comprising:

• deflecting the respective light fluxes from said n light sources with a deflecting device;
• converging light fluxes deflected by said deflecting device toward said surface to be scanned with a scan imaging optical device, such that each light flux from the light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions;
• forming one-dot lines on each partial scanning portion of said n partial scanning portions by scanning with one of said respective light fluxes;
• and
• with a line width Li, where i=1 through n, and a line concentration Di of said one-dot lines formed by scanning with a light flux near a center portion of an ith partial scanning portion of said n partial scanning portions, setting a first optical scanning condition such that an average value Ave{(Li)×Di{circumflex over ( )}(⅕)}, a maximum value Max{(Li)×Di{circumflex over ( )}(⅕)}, and a minimum value Min {(Li)×Di{circumflex over ( )}(⅕)}, of computation values (Li)×Di{circumflex over ( )}(⅕) of said one-dot lines satisfy a first condition of:
• Max{(Li)×Di{circumflex over ( )}(⅕)}/1.15<Ave{(Li)×Di{circumflex over ( )}(⅕)}<Min{(Li)×Di{circumflex over ( )}(⅕)}/0.85.

An optical scanning method which divides an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction thereof and which uses n light sources respectively corresponding to said n partial scanning portions to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas, the method comprising:

• deflecting the respective light fluxes from said n light sources with a deflecting device;
• converging light fluxes deflected by said deflecting device toward said surface to be scanned with a scan imaging optical device, such that each light flux from the light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions;
• forming one-dot lines on each partial scanning portion of said n partial scanning portions by scanning with one of said respective light fluxes;
• and
• with a first line width ratio Li/Li+1, where i=1 through n−1, of said one-dot lines formed by scanning with a light flux elongated in a sub-scanning direction near a seam between an ith partial scanning portion and an i+1th partial scanning portion denoted as a sub-scanning line width ratio KS, setting a first optical scanning condition such that the sub-scanning line width ratio KS satisfies a first ratio condition of:
• 0.9<KS<1.1.

An optical scanning method which divides an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction thereof and which uses n light sources respectively corresponding to said n partial scanning portions to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas, the method comprising:

• deflecting the respective light fluxes from said n light sources with a deflecting device;
• converging light fluxes deflected by said deflecting device toward said surface to be scanned with a scan imaging optical device, such that each light flux from the light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions;
• forming one-dot lines on each partial scanning portion of said n partial scanning portions by scanning with one of said respective light fluxes;
• and
• with a line width ratio Li/Li+1, where i=1 through n−1, of said one-dot lines formed by scanning with a light flux elongated in a main scanning direction near a seam between an ith partial scanning portion and an i+1th partial scanning portion denoted as a main scanning line width ratio KM, setting an optical scanning condition such that the main scanning line width ratio KM satisfies a condition of:
• 0.93<KM<1.07.

An optical scanning method which divides an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction thereof and which uses n light sources respectively corresponding to said n partial scanning portions to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas, the method comprising:

• deflecting the respective light fluxes from said n light sources with a deflecting device;
• converging light fluxes deflected by said deflecting device toward said surface to be scanned with a scan imaging optical device, such that each light flux from the light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions;
• forming one-dot lines on each partial scanning portion of said n partial scanning portions by scanning with one of said respective light fluxes;
• and
• with a first line width ratio Li/Li+1, where i=1 through n−1, of said one-dot lines formed by scanning with a light flux elongated in a sub-scanning direction near a seam between an ith partial scanning portion and an i+1th partial scanning portion denoted as a sub-scanning line width ratio KS and a first line concentration ratio Di/Di+1 denoted as a line concentration ratio HS, setting a first optical scanning condition such that a computation amount (KS)×HS{circumflex over ( )}(⅕) of said one-dot lines satisfies a first condition of:
• 0.9<(KS)×HS{circumflex over ( )}(⅕)<1.1.

An optical scanning method which divides an area to be scanned on a surface to be scanned into n (wherein n≧2) partial scanning portions in a longitudinal direction thereof and which uses n light sources respectively corresponding to said n partial scanning portions to optically scan said n partial scanning portions with respective light fluxes from said n light sources thereby to scan said areas, the method comprising:

• deflecting the respective light fluxes from said n light sources with a deflecting device;
• converging light fluxes deflected by said deflecting device toward said surface to be scanned with a scan imaging optical device, such that each light flux from the light sources forms an optical spot on a corresponding partial scanning portion of said n partial scanning portions;
• forming one-dot lines on each partial scanning portion of said n partial scanning portions by scanning with one of said respective light fluxes;
• and
• with a line width ratio Li/Li+1, where i=1 through n−1, of said one-dot lines formed by scanning with a light flux elongated in a main scanning direction near a seam between an ith partial scanning portion and an i+1th partial scanning portion denoted as a main scanning line width ratio KM and a line concentration ratio Di/Di+1 denoted as a line concentration ratio HM, setting an optical scanning condition such that a computation amount (KM)×HM{circumflex over ( )}(⅕) of said one-dot lines satisfies a computational condition of:
• 0.93<(KM)×HM{circumflex over ( )}(⅕) 21 1.07.