Claims
- 1. A fixing device for fixing a toner image on the surface of a sheet material comprising:
- a rotatably mounted driven fixing roller adapted to be drivingly connected to a drive source;
- a rotatably mounted follower fixing roller;
- a movable supporting member mounting at least one end of the follower fixing roller for free movement between a press-contacting position at which the follower fixing roller is maintained in press-contact with the driven fixing roller and an isolated position at which at least a greater portion of the follower fixing roller in its longitudinal direction is isolated from, or maintained out of press contact with, the driven fixing roller; and
- a press-contacting control mechanism for moving the movable supporting member to the press-contacting position upon energization of a drive source to which the driven fixing roller is drivingly connected and to the isolated position upon deenergization of such drive source.
- 2. The fixing device of claim 1 wherein:
- the press-contacting control mechanism includes a positioning member which is moved to an operating position when such drive source is energized and to a non-operating position when the drive source is deenergized, and a tension spring member connecting the positioning member to the movable supporting member so that when the positioning member is moved to the operating position, the movable supporting member is moved to the press-contacting position via the tension spring member, whereby the follower fixing roller is maintained in press contact with the driven fixing roller by the elastic action of the tension spring member.
- 3. The fixing device of claim 2 wherein:
- the press-contacting control mechanism includes a rotatable input element adapted to be drivingly connected to the drive source, a rotatably mounted cam plate, means defining a stationary position, an energy storing spring means fixed at one end to the cam plate and at other end to the stationary position defining means, and a double spring clutch means interposed between the rotatable input element and the cam plate so that when the drive source is energized, the rotatable input element is rotated in a predetermined direction, and the rotation of the input element is transmitted to the cam plate via the double spring clutch means until the cam plate is rotated to an operating angular position in said predetermined direction against the elastic action of the energy storing spring means, and when the cam plate is thus held at the operating angular position, the positioning member is moved to said operating position; and
- when the drive source is deenergized, the cam plate is rotated to a non-operating angular position in a direction opposite to said predetermined direction by the energy stored in the energy storing spring means, and thus when the cam plate is held at the non-operating position, the positioning means is moved to said non-operating position.
- 4. The fixing device of claim 3 wherein the double spring clutch means comprises a first rotating element, a second rotating element, a third rotating element, a first coil spring received about a hub portion of the rotating input element and a first hub portion of the second rotating element and wrapped from its one end connected to the rotating input element to its other end connected to the first rotating element in a direction in which it is shrunken when the rotating input element is rotated in said predetermined direction, a second coil spring received about a second hub portion of the second rotating element and a hub portion of the cam plate and wrapped from its one end connected to the third rotating element to its other end connected to the cam plate in a direction in which it is shrunken when the second rotating element is rotated in said predetermined direction, hampering means for hampering the rotation of the first rotating element in said opposite direction, and restricting means for restricting the rotation of the third rotating element in said predetermined direction to said operating angular position of the cam plate and also the rotation of the third rotating element in said opposite direction to said non-operating angular position of the cam plate.
- 5. The fixing device of claim 4 wherein the first rotating element is a first gear, and the hampering means is comprised of a hampering gear rotatably mounted on a supporting shaft and engaged with said first gear and a coil spring received about a hub portion of the hampering gear and the supporting shaft and wrapped in a direction in which it is shrunken when the hampering gear is rotated incident to the rotation of said first gear in said opposite direction.
- 6. The fixing device of claim 5 wherein the supporting shaft is a rotatable shaft fixed to the positioning member.
- 7. The fixing device of claim 4 wherein the restricting means is comprised of at least one projection formed in the third rotating element and a stationary stop member against which the projection is to abut.
- 8. The fixing device of claim 1 wherein the follower fixing roller is formed of a soft flexible material.
- 9. The fixing device of claim 1 wherein the driven fixing roller has an electrical heating element therein.
Priority Claims (1)
Number |
Date |
Country |
Kind |
57-209849 |
Nov 1982 |
JPX |
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Parent Case Info
This is a continuation, division of application Ser. No. 551,794, filed Nov. 15, 1983.
US Referenced Citations (4)
Divisions (1)
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Number |
Date |
Country |
Parent |
551794 |
Nov 1983 |
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