Claims
- 1. An image forming apparatus comprising:
- image forming means for forming an unfixed toner image on recording material;
- fixing means having a pair of rotatable members for conveying the recording material therebetween and fixing said unfixed toner image on the recording material, a distance along a conveyance path of the recording material between a position at which the unfixed toner image is formed on the recording material by said image forming means and a nip position of said pair of rotatable members being shorter than the length of the recording material used with respect to a direction of conveyance of the recording material;
- conveying means for conveying the recording material having said unfixed toner image formed thereon to said fixing means;
- drive means for rotatably driving said pair of rotatable members selectively at a first peripheral speed lower than a speed at which said conveying means conveys the recording material and a second peripheral speed higher than the speed at which said conveying means conveys the recording material; and
- control means for controlling said drive means, said control means controlling said drive means so as to rotate said pair of rotatable members at said first peripheral speed to thereby convey the recording material and to form a loop of the recording material having said unfixed toner image formed thereon between the nip position of said pair of rotatable members and the position at which the unfixed toner image is formed on the recording material by said image forming means, and thereafter to change said first peripheral speed to said second peripheral speed, thereby suppressing growth of the loop of said recording material greater than a predetermined amount.
- 2. An image forming apparatus according to claim 1, further comprising detector means for detecting a leading edge of the conveyed recording material at the upstream side of said pair of rotatable members with respect to the direction of conveyance of the recording material and wherein the peripheral speed of said pair of rotatable members is set to said first peripheral speed in accordance with a detection signal produced when said detector means detects the leading edge of said recording material.
- 3. An image forming apparatus according to claim 2, wherein in a predetermined time after the peripheral speed of said pair of rotatable members is set to said first peripheral speed, the peripheral speed of said pair of rotatable members is changed over from said first peripheral speed to said second peripheral speed, said predetermined time corresponding to the time from setting the peripheral speed of said pair of rotatable members to said first peripheral speed until a loop of the recording material of a predetermined size is formed.
- 4. An image forming apparatus according to claim 3, wherein before said detector means detects the leading edge of the recording material, said pair of rotatable members are rotatively driven at said second peripheral speed.
- 5. An image forming apparatus according to claim 1, further comprising detector means for detecting the size of the loop of said recording material and wherein the peripheral speed of said pair of rotatable members is set to said second peripheral speed in accordance with a detection signal produced when said detector means detects that the loop of said recording material has assumed a predetermined size.
- 6. An image forming apparatus according to claim 5, wherein said detector means has first and second detecting portions for detecting the loop of the recording material at two different height positions in order to maintain the size of the loop of the recording material at a predetermined size.
- 7. An image forming apparatus according to claim 1, wherein said fixing means is heating-fixing means.
- 8. An image forming apparatus according to claim 7, wherein the amount of heat imparted to the recording material at the nip position between said pair of rotatable members when said second peripheral speed is selected as the peripheral speed of said pair of rotatable members is greater than when said first peripheral speed is selected.
- 9. An image forming apparatus according to claim 1, wherein said image forming means has an image bearing member, means for forming a latent image on said image bearing member, means for developing the formed latent image into a developed image and means for transferring the developed image on said image bearing member onto said recording material.
- 10. An image forming apparatus according to claim 9, wherein the unfixed toner image is generated on the recording material at the image transfer position.
- 11. An image forming apparatus according to claim 9, wherein a plurality of said image forming means are disposed along the conveyance path of the recording material, and developed images of different colors are transferred onto the recording material from the image bearing members of the respective image forming means.
- 12. An image forming apparatus according to claim 11, wherein the loop of said recording material is formed between the nip position between said pair of rotatable members and a transfer position of one of said plurality of image forming means which is most downstream with respect to the direction of conveyance of the recording material.
- 13. An image forming apparatus according to claim 11, wherein said conveying means is in the form of belt-like conveying means, and said belt-like conveying means supports the recording material thereon, passes the recording material to transfer stations of said plurality of image forming means, and thereafter conveys the recording material to said fixing means.
Priority Claims (2)
Number |
Date |
Country |
Kind |
61-3185 |
Jan 1986 |
JPX |
|
61-3186 |
Jan 1986 |
JPX |
|
Parent Case Info
This application is a continuation of application Ser. No. 001,176, filed Jan. 7, 1987, now abandoned.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
3937919 |
Clerx et al. |
Feb 1976 |
|
Continuations (1)
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Number |
Date |
Country |
Parent |
1176 |
Jan 1987 |
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