JPS58186771A - Fixation device - Google Patents

Abstract

PURPOSE:To prevent oil contamination of transfer paper even if oil adheres to the tip of a pawl member, by providing an auxiliary pawl for turning and displacing its position as transfer paper advances. CONSTITUTION:The tip of transfer paper 6 heated and fixed by a pair of fixation rolls 4 is caught into the side of a pair of paper discharge rolls 8, running along the lower face of a peel-off pawl 11. In this state, a tip 17a of an auxiliary pawl 17 is in the first position state which is shunted, therefore, such a carrying trouble as the tip of the transfer paper 6 is caught by the tip 17a does not occur. When the tip of the transfer paper 6 reaches a step in which it is held by a pair of the rolls 8, pressure in the upper direction operates on a rear end 17b of the auxiliary pawl 17 and it is turned and displaced. Subsequently, its tip 17a takes the second position for advancing to the side of a carrying path 16 from the peel-off pawl 11, by which the transfer paper is guided so as to be separated from the peel-off pawl 11 forcibly even in case of a carrying state of the rear end of the transfer paper 6 is apt to be curled upwards, therefore, the rear end of the transfer paper contacts in the vicinity of the tip of the peel- off pawl 11, and its adhering oil 13a does not adhere to it.

Description

[Detailed description of the invention] The present invention relates to a fixing device.

Generally, a fixing device consists of a heating roller (2) with a built-in heater (1) and a pressure roller (3), as shown in FIG.
) are provided in opposing contact with each other.
There are many systems in which a transfer paper (6) carrying a toner image (5) is passed through and fixed by heating. Then, the fixing roller pair (
The transfer paper (6) that has passed through the transfer roller 4) is discharged by a pair of paper discharge rollers (8) via a guide plate (7). At this point, the leading edge of the fixed transfer paper (6) may not be peeled off from the heating roller (2) but may become wrapped around it, so the spring (9) is used so that the leading edge contacts the heating roller (2) to forcefully peel it off. A peeling claw α force is provided which is biased by and rotatable with respect to the shaft 01. In addition, an oil applicator (g) that pumps up oil α such as silicone oil stored in the oil pan 0'4 with a coating felt α and applies it onto the heating roller (2) to prevent offset etc. is also installed. It is provided.

However, since the tip of the peeling claw α■ is in contact with the heating roller (2), the oil coated on the heating roller (2) is scraped off by the tip of the peeling claw α■ and adheres to its lower surface. On the other hand, in the free state where the rear end of the transfer paper (6) has come out from the fixing roller pair (4) to the conveyance path (2) between the peeling claw α■ and the guide plate (7), the heating roller Due to the influence of heat caused by (2), it tends to curl upward, that is, toward the peeling claw αη side, as shown by the dashed line, and therefore, the attached oil (laa) adheres to the rear end and becomes dirty.

The present invention has been made in view of these points, and an object of the present invention is to provide a fixing device that can eliminate stains on transfer paper due to oil adhering to a peeling claw member.

The present invention provides a second position in which the leading edge is rotatably supported at a first position where the claw member is also retracted from the conveying path, and the leading edge advances toward the conveying path by pressing the trailing edge as the transfer paper advances. By providing an auxiliary pawl that moves to take the correct position, even if oil/lz adheres to the tip of the pawl, the transfer paper is forcibly maintained in a state separated from the pawl by the auxiliary pawl, thereby eliminating oil stains. The structure is designed to prevent this from occurring.

An embodiment of the present invention will be described based on FIGS. 2 and 3. Components that are the same as those shown in FIG. 1 are designated by the same reference numerals, and description thereof will be omitted. In this embodiment, the tip (1
7cL) and a rear end (17-M). Here, in the normal state, this auxiliary claw 7) is regulated by the stopper M and is pulled by the spring (to) so that its tip (17α) becomes the peeling claw O.
] is also in the first position evacuated from the conveyance path αQ (see Figure 2)
It is set to take .

At this time, the rear end (the 17th stage is set to advance into the transport path aQ at the front stage of the paper ejection roller pair (8). Also, the tension of the spring (end) is stronger as the left side However, as shown in Figure 3, when the rear end (17) that had advanced into the conveyance path αQ was suppressed by the advancement of the transfer paper (6), the tip (17a) was removed by the peeling claw α It is also set to be displaced to the second position advanced relative to the carrier 11Q.

Note that the heating roller (2) is heated by the heater (1) to keep its surface temperature constant.The pressure roller (3) has a surface layer made of an elastic material and is heated by the heater (1) to keep its surface temperature constant. 2) is in pressure contact with.

In such a configuration, since the leading edge of the transfer paper (6) that has been heated and fixed by the pair of fixing rollers (4) tends to curl upward, the pair of paper ejection rollers (8)
Caught in the side. The second part shows the operation during the process.
In this state, the tip of the auxiliary claw α force (17tL)
Since the transfer paper (6) is in the retracted first position, there will be no conveyance trouble such as the leading edge of the transfer paper (6) being caught by the leading edge (17α). Therefore, the leading edge of the transfer paper (6) is connected to the paper ejection roller pair (
8), as the transfer paper (6) advances, an upward pressing force acts on the rear end (17+) of the auxiliary claw C17), and the auxiliary claw α force is as shown in Fig. 3. It is rotated and displaced as shown in . In other words, its tip (17 m) is the peeling claw α
In this state, the rear end of the transfer paper (6) is in the second position where it advances to the conveyance path aQ side.
4) is continued until the end. Therefore, as shown by the dashed line in FIG. 3, the rear end of the transfer paper (6) passes through the pair of fixing rollers (4), becomes free in the conveyance path (2), and tends to curl upward. Even if the separation claw α
The transfer paper (6) will be guided away from the tent.
There is no possibility that the rear end of the peeling claw 0) comes into contact with the vicinity of the tip of the peeling claw 0]) and that the attached oil (laa) is deposited thereon.

Therefore, oil stains on the rear end of the transfer paper (6) are prevented.

In this embodiment, the p auxiliary claw α force is maintained at the first position by the spring α field, and therefore by the external force.
The second position may be secured by the weight of the auxiliary claw αη. Furthermore, the center of rotation of the auxiliary claw αη is not limited to the one in which the axis (g) is shared with the peeling claw αυ as in this embodiment, but it is also possible to use a method such as providing an independent axis in the vicinity thereof. good.

As described above, the present invention maintains the first position where the leading end is rotatably supported and retracted from the claw member with respect to the conveyance path, and the leading end is reversed by the pressure against the trailing end as the transfer paper advances. Since we have provided an auxiliary pawl that advances toward the conveyance path side and is displaced over multiple positions, even if the trailing edge of the free transfer paper that has passed through the pair of fixing rollers tries to contact the pawl member, the auxiliary pawl that has advanced will not be affected. The tip is maintained in a separated state, and therefore, it is possible to reliably prevent oil stains such as oil adhering to the tip of the claw member from adhering to the rear end of the transfer paper, and it is possible to obtain high-quality copies.

[Brief explanation of drawings]

FIG. 1 is a side view showing a conventional example, FIG. 2 is a side view showing an embodiment of the present invention in a first position, and FIG. 3 is a side view showing the second position. 2... Heat roller (fixing roller), 3... Pressure roller (fixing roller), 4... Fixing roller pair, 5... Toner image, 6... Transfer paper, 11... Peeling Claw (claw member)
, 13... Oil, 15... Oil applicator, 16
...Conveyance path, 17...Auxiliary claw, 1711...Tip, 17k...Rear end Applicant Ricoh Co., Ltd.

Claims (1)

[Claims] A pair of fixing rollers that heat and fix the toner image on the transfer paper, a claw member whose tip comes into contact with one of the fixing rollers in contact with the toner image and peels the transfer paper from the fixing roller, and a nail member that applies oil on the fixing roller. In the fixing device, the fixing roller has a leading end and a trailing end along a conveying path after the fixing roller pair, and the leading end rotates at a first position retracted from the pawl member with respect to the conveying path. An auxiliary claw is provided that is freely supported and is displaced by pressure on the rear end as the transfer paper advances, so that the leading end assumes a second position in which the claw member also advances toward the conveyance path. Fixing device.