Image forming apparatus with specialized sheet conveyance speed control

An image forming apparatus comprising:

• image forming means including an image bearing member for bearing a toner image, and a sheet material supporting member for supporting a sheet material to which the toner image is transferred, and adapted to hold and convey the sheet material between the image bearing member and the sheet material supporting member to thereby transfer the toner image on the image bearing member to the sheet material;
• sheet material conveying means for conveying the sheet material toward the image forming means;
• registration means for correcting skew of the sheet material conveyed by the sheet material conveying means and conveying the sheet material to the image forming means with a predetermined timing;
• an image formation driving source for driving the image forming means;
• a conveyance system driving source for driving the sheet material conveying means and the registration means;
• first drive transmitting means and second drive transmitting means for transmitting a drive from the conveyance system driving source to the sheet material conveying means at different transmission ratios;
• transmission ratio switching means for switching drive transmission between the first drive transmitting means and the second drive transmitting means;
• and
• control means which makes a speed at which the sheet material is conveyed by the sheet material conveying means variable and which controls the conveyance system driving source and the image formation driving source such that a speed at which the sheet material is conveyed by the registration means is substantially the same as the speed at which the sheet material is conveyed by the image forming means and which controls the transmission ratio switching means such that when the sheet material is conveyed to the registration means, the drive of the conveyance system driving source is transmitted to the sheet material conveying means through the first drive transmitting means, and that when the sheet material is conveyed to the image forming means by the registration means, the drive of the conveyance system driving source is transmitted to the sheet material conveying means through the second drive transmitting means.

An image forming apparatus comprising:

• image forming means for conveying a sheet material and forming an image on a sheet material;
• conveying means for conveying the sheet material toward the image forming means;
• an image formation driving source for driving the image forming means;
• a conveyance system driving source for driving the conveying means;
• and
• control means which makes a speed at which the sheet material is conveyed by the image forming means variable according to a kind of sheet material, which makes a speed at which the sheet material is conveyed by the conveying means substantially the same as a speed at which the sheet material is conveyed by the image forming means when an image is formed on the sheet material by said image forming means, and which makes a speed at which the sheet material is conveyed by said sheet material conveying means substantially the same as or faster than a speed at which the sheet material is conveyed by the image forming means before image forming means starts to form an image on the sheet material.