Image forming apparatus and image forming method that detects an amount of color misalignment using reflected light

An image forming apparatus comprising:

• a pattern forming unit that forms a color-misalignment detection pattern on an image carrier;
• a light-intensity detecting unit that detects the color-misalignment detection pattern formed on the image carrier by irradiating the image carrier with a light and detecting light intensity of a reflected light from the image carrier;
• and
• a color-misalignment-amount detecting unit that detects an amount of a color misalignment of an image based on the light intensity of the reflected light detected by the light-intensity detecting unit,
• wherein:
• a spot of the light on the image carrier is elongated in a main-scanning direction,
• the color-misalignment detection pattern includes a main-scanning-direction misalignment detection pattern for detecting a color misalignment in the main-scanning direction or a sub-scanning-direction misalignment detection pattern for detecting a color misalignment in a sub-scanning direction,
• the pattern forming unit forms one of the main-scanning-direction misalignment detection pattern and the sub-scanning-direction misalignment detection pattern including a first pattern for a predetermined reference color and a second pattern for a non-reference color other than the reference color arranged being overlapped with each other on the image carrier,
• the first pattern is formed without forming the second pattern in a specific region, and
• the light-intensity detecting unit detects the amount of the color misalignment in one of the main-scanning direction and the sub-scanning direction based on a variation in the light intensity caused by shifts of the reflected lights from the first pattern and the second pattern in one of the main-scanning direction and the sub-scanning direction,
• the image forming apparatus further comprising:
• a determining unit that determines that there is a large color misalignment in one of the main-scanning direction and the sub-scanning direction when a value obtained by (Vmax-VBk)/VBk is smaller than a preset determination value, where Vmax is a maximum output of one of the main-scanning-direction misalignment detection pattern and the sub-scanning-direction misalignment detection pattern from the light-intensity detecting unit and VBk is an output of the first pattern from the light-intensity detecting unit.

An image forming apparatus comprising:

• a pattern forming unit that forms a color-misalignment detection pattern on an image carrier;
• a light-intensity detecting unit that detects the color-misalignment detection pattern formed on the image carrier by irradiating the image carrier with a light and detecting light intensity of a reflected light from the image carrier;
• and
• a color-misalignment-amount detecting unit that detects an amount of a color misalignment of an image based on the light intensity of the reflected light detected by the light-intensity detecting unit,
• wherein:
• a spot of the light on the image carrier is elongated in a main-scanning direction,
• the color-misalignment detection pattern includes a main-scanning-direction misalignment detection pattern for detecting a color misalignment in the main-scanning direction or a sub-scanning-direction misalignment detection pattern for detecting a color misalignment in a sub-scanning direction,
• the pattern forming unit forms one of the main-scanning-direction misalignment detection pattern and the sub-scanning-direction misalignment detection pattern including a first pattern for a predetermined reference color and a second pattern for a non-reference color other than the reference color arranged being overlapped with each other on the image carrier,
• the first pattern is formed without forming the second pattern in a specific region, and
• the light-intensity detecting unit detects the amount of the color misalignment in one of the main-scanning direction and the sub-scanning direction based on a variation in the light intensity caused by shifts of the reflected lights from the first pattern and the second pattern in one of the main-scanning direction and the sub-scanning direction,
• the image forming apparatus further comprising:
• a determining unit that determines that there is a large color misalignment in one of the main-scanning direction and the sub-scanning direction when a value obtained by (Vmax-VBk)/(VBk-V0) is smaller than a preset determination value, where Vmax is a maximum output of one of the main-scanning-direction misalignment detection pattern and the sub-scanning-direction misalignment detection pattern from the light-intensity detecting unit, VBk is an output of the first pattern from the light-intensity detecting unit, and V0 is an output without patterns from the light-intensity detecting unit.

An image forming apparatus comprising:

• a pattern forming unit that forms a color-misalignment detection pattern on an image carrier;
• a light-intensity detecting unit that detects the color-misalignment detection pattern formed on the image carrier by irradiating the image carrier with a light and detecting light intensity of a reflected light from the image carrier;
• and
• a color-misalignment-amount detecting unit that detects an amount of a color misalignment of an image based on the light intensity of the reflected light detected by the light-intensity detecting unit,
• wherein:
• a spot of the light on the image carrier is elongated in a main-scanning direction,
• the color-misalignment detection pattern includes a main-scanning-direction misalignment detection pattern for detecting a color misalignment in the main-scanning direction or a sub-scanning-direction misalignment detection pattern for detecting a color misalignment in a sub-scanning direction,
• the pattern forming unit forms one of the main-scanning-direction misalignment detection pattern and the sub-scanning-direction misalignment detection pattern including a first pattern for a predetermined reference color and a second pattern for a non-reference color other than the reference color arranged being overlapped with each other on the image carrier,
• the first pattern is formed without forming the second pattern in a specific region, and
• the light-intensity detecting unit detects the amount of the color misalignment in one of the main-scanning direction and the sub-scanning direction based on a variation in the light intensity caused by shifts of the reflected lights from the first pattern and the second pattern in one of the main-scanning direction and the sub-scanning direction,
• the image forming apparatus further comprising:
• a determining unit that determines that there is a large color misalignment in one of the main-scanning direction and the sub-scanning direction when a value obtained by (Vmax-VBk)/(Vmin-VBk) is smaller than a preset determination value, where Vmax is a maximum output of one of the main-scanning-direction misalignment detection pattern and the sub-scanning-direction misalignment detection pattern from the light-intensity detecting unit, VBk is an output of the first pattern from the light-intensity detecting unit, and Vmin is a minimum output of one of the main-scanning-direction misalignment detection pattern and the sub-scanning-direction misalignment detection pattern from the light-intensity detecting unit.

An image forming apparatus comprising:

• a pattern forming unit that forms a color-misalignment detection pattern on an image carrier;
• a light-intensity detecting unit that detects the color-misalignment detection pattern formed on the image carrier by irradiating the image carrier with a light and detecting light intensity of a reflected light from the image carrier;
• and
• a color-misalignment-amount detecting unit that detects an amount of a color misalignment of an image based on the light intensity of the reflected light detected by the light-intensity detecting unit,
• wherein:
• a spot of the light on the image carrier is elongated in a main-scanning direction,
• the color-misalignment detection pattern includes a main-scanning-direction misalignment detection pattern for detecting a color misalignment in the main-scanning direction or a sub-scanning-direction misalignment detection pattern for detecting a color misalignment in a sub-scanning direction,
• the pattern forming unit forms one of the main-scanning-direction misalignment detection pattern and the sub-scanning-direction misalignment detection pattern including a first pattern for a predetermined reference color and a second pattern for a non-reference color other than the reference color arranged being overlapped with each other on the image carrier,
• the first pattern is formed without forming the second pattern in a specific region, and
• the light-intensity detecting unit detects the amount of the color misalignment in one of the main-scanning direction and the sub-scanning direction based on a variation in the light intensity caused by shifts of the reflected lights from the first pattern and the second pattern in one of the main-scanning direction and the sub-scanning direction,
• the image forming apparatus further comprising:
• a determining unit that determines that there is a large color misalignment in one of the main-scanning direction and the sub-scanning direction when a value obtained by (Vmin-VBk)/VBk is larger than a preset determination value, where VBk is an output of the first pattern from the light-intensity detecting unit and Vmin is a minimum output of one of the main-scanning-direction misalignment detection pattern and the sub-scanning-direction misalignment detection pattern from the light-intensity detecting unit.

An image forming apparatus comprising:

• a pattern forming unit that forms a color-misalignment detection pattern on an image carrier;
• a light-intensity detecting unit that detects the color-misalignment detection pattern formed on the image carrier by irradiating the image carrier with a light and detecting light intensity of a reflected light from the image carrier;
• and
• a color-misalignment-amount detecting unit that detects an amount of a color misalignment of an image based on the light intensity of the reflected light detected by the light-intensity detecting unit,
• wherein:
• a spot of the light on the image carrier is elongated in a main-scanning direction,
• the color-misalignment detection pattern includes a main-scanning-direction misalignment detection pattern for detecting a color misalignment in the main-scanning direction or a sub-scanning-direction misalignment detection pattern for detecting a color misalignment in a sub-scanning direction,
• the pattern forming unit forms one of the main-scanning-direction misalignment detection pattern and the sub-scanning-direction misalignment detection pattern including a first pattern for a predetermined reference color and a second pattern for a non-reference color other than the reference color arranged being overlapped with each other on the image carrier,
• the first pattern is formed without forming the second pattern in a specific region, and
• the light-intensity detecting unit detects the amount of the color misalignment in one of the main-scanning direction and the sub-scanning direction based on a variation in the light intensity caused by shifts of the reflected lights from the first pattern and the second pattern in one of the main-scanning direction and the sub-scanning direction,
• the image forming apparatus further comprising:
• a determining unit that determines that there is a large color misalignment in one of the main-scanning direction and the sub-scanning direction when a value obtained by (Vmin-VBk)/(VBk-V0) is larger than a preset determination value, where VBk is an output of the first pattern from the light-intensity detecting unit, Vmin is a minimum output of one of the main-scanning-direction misalignment detection pattern and the sub-scanning-direction misalignment detection pattern from the light-intensity detecting unit, and V0 is an output without patterns from the light-intensity detecting unit.

An image forming apparatus comprising:

• a pattern forming unit that forms a color-misalignment detection pattern on an image carrier;
• a light-intensity detecting unit that detects the color-misalignment detection pattern formed on the image carrier by irradiating the image carrier with a light and detecting light intensity of a reflected light from the image carrier;
• and
• a color-misalignment-amount detecting unit that detects an amount of a color misalignment of an image based on the light intensity of the reflected light detected by the light-intensity detecting unit,
• wherein:
• a spot of the light on the image carrier is elongated in a main-scanning direction,
• the color-misalignment detection pattern includes a main-scanning-direction misalignment detection pattern for detecting a color misalignment in the main-scanning direction or a sub-scanning-direction misalignment detection pattern for detecting a color misalignment in a sub-scanning direction,
• the pattern forming unit forms one of the main-scanning-direction misalignment detection pattern and the sub-scanning-direction misalignment detection pattern including a first pattern for a predetermined reference color and a second pattern for a non-reference color other than the reference color arranged being overlapped with each other on the image carrier,
• the first pattern is formed without forming the second pattern in a specific region, and
• the light-intensity detecting unit detects the amount of the color misalignment in one of the main-scanning direction and the sub-scanning direction based on a variation in the light intensity caused by shifts of the reflected lights from the first pattern and the second pattern in one of the main-scanning direction and the sub-scanning direction,
• the image forming apparatus further comprising:
• a determining unit that determines that there is a large color misalignment in one of the main-scanning direction and the sub-scanning direction when a value obtained by Vmax-Vmin is smaller than a preset determination value, where Vmax is a maximum output of one of the main-scanning-direction misalignment detection pattern and the sub-scanning-direction misalignment detection pattern from the light-intensity detecting unit and Vmin is a minimum output of one of the main-scanning-direction misalignment detection pattern and the sub-scanning-direction misalignment detection pattern from the light-intensity detecting unit.

An image forming apparatus comprising:

• a pattern forming unit that forms a color-misalignment detection pattern on an image carrier;
• a light-intensity detecting unit that detects the color-misalignment detection pattern formed on the image carrier by irradiating the image carrier with a light and detecting light intensity of a reflected light from the image carrier;
• and
• a color-misalignment-amount detecting unit that detects an amount of a color misalignment of an image based on the light intensity of the reflected light detected by the light-intensity detecting unit,
• wherein:
• a spot of the light on the image carrier is elongated in a main-scanning direction,
• the color-misalignment detection pattern includes a main-scanning-direction misalignment detection pattern for detecting a color misalignment in the main-scanning direction or a sub-scanning-direction misalignment detection pattern for detecting a color misalignment in a sub-scanning direction,
• the pattern forming unit forms one of the main-scanning-direction misalignment detection pattern and the sub-scanning-direction misalignment detection pattern including a first pattern for a predetermined reference color and a second pattern for a non-reference color other than the reference color arranged being overlapped with each other on the image carrier,
• the first pattern is formed without forming the second pattern in a specific region, and
• the light-intensity detecting unit detects the amount of the color misalignment in one of the main-scanning direction and the sub-scanning direction based on a variation in the light intensity caused by shifts of the reflected lights from the first pattern and the second pattern in one of the main-scanning direction and the sub-scanning direction,
• the image forming apparatus further comprising:
• a determining unit that determines that there is a large color misalignment in one of the main-scanning direction and the sub-scanning direction when a value obtained by Vmax-VBk is smaller than a preset determination value, where Vmax is a maximum output of one of the main-scanning-direction misalignment detection pattern and the sub-scanning-direction misalignment detection pattern from the light-intensity detecting unit and VBk is an output of the first pattern from the light-intensity detecting unit.

An image forming apparatus comprising:

• a pattern forming unit that forms a color-misalignment detection pattern on an image carrier;
• a light-intensity detecting unit that detects the color-misalignment detection pattern formed on the image carrier by irradiating the image carrier with a light and detecting light intensity of a reflected light from the image carrier;
• and
• a color-misalignment-amount detecting unit that detects an amount of a color misalignment of an image based on the light intensity of the reflected light detected by the light-intensity detecting unit,
• wherein:
• a spot of the light on the image carrier is elongated in a main-scanning direction,
• the color-misalignment detection pattern includes a main-scanning-direction misalignment detection pattern for detecting a color misalignment in the main-scanning direction or a sub-scanning-direction misalignment detection pattern for detecting a color misalignment in a sub-scanning direction,
• the pattern forming unit forms one of the main-scanning-direction misalignment detection pattern and the sub-scanning-direction misalignment detection pattern including a first pattern for a predetermined reference color and a second pattern for a non-reference color other than the reference color arranged being overlapped with each other on the image carrier,
• the first pattern is formed without forming the second pattern in a specific region, and
• the light-intensity detecting unit detects the amount of the color misalignment in one of the main-scanning direction and the sub-scanning direction based on a variation in the light intensity caused by shifts of the reflected lights from the first pattern and the second pattern in one of the main-scanning direction and the sub-scanning direction,
• the image forming apparatus further comprising:
• a storage unit that stores therein a plurality of determination conditions selected from
• {(Vmax-VBk)/VBk}<(determination value)
• {(Vmax-VBk)/(VBk-V0)}<(determination value)
• {(Vmax-VBk)/(Vmin-VBk)}<(determination value)
• {(Vmin-VBk)/VBk}>(determination value)
• {(Vmin-VBk)/(VBk-V0)}>(determination value)
• (Vmax-Vmin)<(determination value)
• (Vmax-VBk)<(determination value)
• where Vmax is a maximum output of one of the main-scanning-direction misalignment detection pattern and the sub-scanning-direction misalignment detection pattern from the light-intensity detecting unit, Vmin is a minimum output of one of the main-scanning-direction misalignment detection pattern and the sub-scanning-direction misalignment detection pattern from the light-intensity detecting unit, VBk is an output of the first pattern from the light-intensity detecting unit, and V0 is an output without patterns from the light-intensity detecting unit;
• and
• a determining unit that determines that there is a large color misalignment in one of the main-scanning direction and the sub-scanning direction when any one of values obtained by the determination conditions stored in the storage unit is satisfied.