Image forming apparatus and image write start position adjusting method for the same

An image forming apparatus capable of successively forming images on a first surface and a second surface of a transfer material and fixing the images, comprising:

• an image carrier;
• a light scanning device that forms a latent image on said image carrier by scanning a light beam based on image data and in accordance with an image clock;
• a horizontal synchronization signal detecting device that detects from the light beam a horizontal synchronization signal for controlling a write start position of the latent image on the image carrier;
• and
• a pulse adjusting device that adjusts a number of pulses of the image clock during image formation on the second surface in accordance with a number of pulses of the image clock corresponding to a distance from said horizontal synchronization signal detecting device to the write start position of the latent image and an expansion/contraction ratio of the transfer material after fixing of the image on the first surface.

An image forming apparatus capable of successively forming images on a first surface and a second surface of a transfer material and fixing the images, comprising:

• an image carrier;
• a light scanning device that forms a latent image on said image carrier by scanning a light beam based on image data and in accordance with an image clock;
• a horizontal synchronization signal detecting device that detects from the light beam a horizontal synchronization signal for controlling a write start position of the latent image on the image carrier;
• a calculating device that calculates a frequency of a second image clock during image formation on the second surface that is different from a frequency of a first image clock during image formation on the first surface, and a number of pulses of the second image clock during image formation on the second surface, in accordance with the frequency of the first image clock during image formation on the first surface, a number of pulses of the first image clock corresponding to a distance from said horizontal synchronization signal detecting device to the write start position of the latent image on the first surface and an expansion/contraction ratio of the transfer material after fixing of the image on the first surface;
• and
• a control device that controls the write start position of the latent image on the second surface in accordance with a result of calculation by said calculating device.

An image forming apparatus capable of successively forming images on a first surface and a second surface of a transfer material and fixing the images, comprising:

• at least one image carrier;
• a plurality of light scanning devices that respectively form latent images on said at least one image carrier by scanning a light beam based on image data and in accordance with an image clock;
• a plurality of horizontal synchronization signal detecting devices that detect from the light beam horizontal synchronization signals for controlling respective write start positions of the respective latent images on the at least one image carrier;
• a plurality of pulse adjusting devices that adjust the respective numbers of pulses of the image clock during image formation on the second surface in accordance with numbers of pulses of the image clock corresponding respectively to distances from respective ones of the plurality of horizontal synchronization signal detecting devices to write start positions of the respective latent images and an expansion/contraction ratio of the transfer material after fixing of the images on the first surface;
• a belt-shaped member;
• an in-surface image positioning device that detects at least one mark provided on said belt-shaped member and adjusts the respective numbers of pulses separately for respective ones of said image forming devices;
• and
• a control device that causes said in-surface image positioning device to adjust the respective numbers of pulses for the respective ones of said image forming devices separately when image formation is carried out on the first surface, and causes at least said counted pulse adjusting devices to adjust the image write start positions of the respective ones of said image forming devices separately when image formation is carried out on the second surface.

An image forming apparatus capable of successively forming images on a first surface and a second surface of a transfer material and fixing the images, comprising:

• at least one image carrier;
• a plurality of light scanning devices that respectively form latent images on said at least one image carrier by scanning a light beam based on image data and in accordance with an image clock;
• a plurality of horizontal synchronization signal detecting devices that detect from the light beam horizontal synchronization signals for controlling respective write start positions of the respective latent images on the at least one image carrier;
• a plurality of pulse adjusting devices that adjust the respective numbers of pulses of the image clock during image formation on the second surface in accordance with numbers of pulses of the image clock corresponding respectively to distances from respective ones of the plurality of horizontal synchronization signal detecting devices to write start positions of the respective latent images and an expansion/contraction ratio of the transfer material after fixing of the images on the first surface;
• a belt-shaped member;
• an in-surface image positioning device that detects at least one mark provided on said belt-shaped member and adjusts the respective numbers of pulses separately for respective ones of said image forming devices;
• and
• a control device that causes said in-surface image positioning device to adjust the respective numbers of pulses for the respective ones of said image forming devices separately when image formation is carried out on the first surface, and causes a corresponding one of said pulse adjusting devices to adjust the image write start position of one of said image forming devices used as a reference separately when image formation is carried out on the second surface.

An image write start position adjusting method for an image forming apparatus that is capable of successively forming images on a first surface and a second surface of a transfer material and fixing the images and includes a plurality of light scanning devices that respectively form latent images on at least one image carrier by scanning a light beam based on image data and in accordance with an image clock, a plurality of horizontal synchronization signal detecting devices that detect from the light beam horizontal synchronization signals for controlling respective write start positions of the respective latent images on at least one image carrier, the method comprising:

• a pulse adjusting step of adjusting the respective numbers of pulses of the image clock during image formation on the second surface in accordance with numbers of pulses of the image clock corresponding respectively to distances from respective ones of the plurality of horizontal synchronization signal detecting devices to write start positions of the respective latent images and an expansion/contraction ratio of the transfer material after fixing of the images on the first surface;
• an in-surface image positioning step of detecting at least one mark provided on one of a belt-shaped member and adjusting the respective numbers of pulses separately for respective ones of the image forming devices;
• and
• a control step of causing said in-surface image positioning step to adjust the respective numbers of pulses for the respective ones of the image forming devices separately when image formation is carried out on the first surface, and causing at least said pulse adjusting step to adjust the image write start positions of the respective ones of the image forming devices separately when image formation is carried out on the second surface.

An image write start position adjusting method for an image forming apparatus that is capable of successively forming images on a first surface and a second surface of a transfer material and fixing the images and includes a plurality of light scanning devices that respectively form latent images on at least one image carrier by scanning a light beam based on image data and in accordance with an image clock, a plurality of horizontal synchronization signal detecting devices that detect from the light beam horizontal synchronization signals for controlling respective write start positions of the respective latent images on the at least one image carrier, the method comprising:

• a pulse adjusting step of adjusting the respective numbers of pulses of the image clock during image formation on the second surface in accordance with numbers of pulses of the image clock corresponding respectively to distances from respective ones of the plurality of horizontal synchronization signal detecting devices to write start positions of the respective latent images and an expansion/contraction ratio of the transfer material after fixing of the images on the first surface;
• an in-surface image positioning step of detecting at least one mark provided on a belt-shaped member and adjusting the respective numbers of pulses separately for respective ones of the image forming devices;
• and
• a control step of causing said in-surface image positioning step to adjust the respective numbers of pulses for the respective ones of the image forming devices separately when image formation is carried out on the first surface, and causing said pulse adjusting step to adjust the image write start position of one of the image forming devices used as a reference separately when image formation is carried out on the second surface.