JPH07122772B2 - Contact / separation mechanism of heat roll fixing device - Google Patents

Description

The present invention relates to a contact / separation mechanism of a heat roll fixing device in an electrophotographic recording apparatus.

[Conventional technology]

 A conventional example will be described with reference to FIG.

If a paper jam occurs between the heat roll 20 and the pressure roll 38 during fixing, first, the grip 21 is pushed down and the locking piece 22 is rotated counterclockwise about the shaft 23 to form a recess. Remove 24 from the stop not shown. Then, the rocking body 25 is pulled around the shaft 26 in the counterclockwise direction as indicated by the arrow 27. Therefore, the guide portion 28 draws a locus indicated by an imaginary line while moving toward the free end side of the notch 30 of the link 29. At this time, the link 29 is angularly displaced clockwise around the pivot 31. When the pin 32 contacts the other end 34 of the through hole 33, the link 29 is prevented from further angular displacement. In this state, the oscillating body 25 can be further angularly displaced in the counterclockwise direction around the shaft 26 to remove the guide portion 28 from the notch 30. By the angular displacement of the link 29 around the pivot 31 in the clockwise direction, the pin 32 is displaced toward the heat roll 20 and the pressure roll 38 and downward. Therefore, the spring 35 supports the support member 36 in a state where the tension force is released. In this way, the pressure roll 38 is displaced downward from the heat roll 20, and the contact between the pressure roll 38 and the heat roll 20 is cut off, so that the printing paper having the paper jam between the heat roll and the pressure roll is pulled out.

[Problems to be Solved by the Invention]

However, when using the conventional means, the heat roll and the pressure roll are brought into contact with each other by manually pushing down the handle, and it takes a long time for manual operation, and the paper remains in contact with the heat roll. Not only may the paper turn yellow due to heat,
The operation was troublesome.

The present invention has been made based on such circumstances,
The purpose is to perform a paper jam removal operation etc. quickly and accurately, and when the operation of the heat roll fixing device is stopped, a part of the printing paper is left in contact with the heat roll for a long time. It is an object of the present invention to provide a contact / separation mechanism of a heat roll fixing device, which can avoid such a situation and can prevent a part of the printing paper from locally yellowing due to overheating by the heat roll.

[Means for Solving the Problems]

In order to solve the above problems and achieve the object, the present invention takes the following means.

That is, a heat roll 2 rotatably provided, a pressure roll 3 for pressing the printing paper 1 to be heat-fixed onto the surface of the heat roll 2, and a pressure roll 3 rotatably supported at an intermediate portion. And a support member 5 whose base end is rotatably supported by a shaft 6,
The support member 5 is provided with means for automatically controlling the rotation of the support member 5 to bring the pressure roll 3 into and out of contact with the heat roll 2.

When the pressure roll 3 is separated from the heat roll 2, the support member 5 comes into contact with the heat roll contact surface side of the printing paper 1 at the tip portion thereof, and the printing operation is performed in accordance with the separation operation of the pressure roll 3. A printing paper guide portion 5'for separating the paper 1 from the heat roll 2 is provided.

[Action]

 As a result of taking the above measures, the following effects occur.

(A) Automatic contact / separation means (plunger magnet 11, lever
10, reset lever 16, link plate 8, springs 7,9,
Since the support member 5 is automatically controlled to rotate by the reset cam 17 and the calforer 18, etc., the pressure roll 3 automatically comes into contact with and separates from the heat roll 2. Therefore, it is possible to perform a paper jam removal operation and the like quickly and accurately.

(B) When the pressure roll 3 starts the separating operation from the heat roll 2 by the automatic contacting / separating means when the operation of the heat roll fixing device is stopped, the heat roll 2 until then.
Printing paper that should be heated and fixed against the surface of the paper 1
Is pulled in a direction away from the heat roll 2 by a printing paper guide portion 5 ′ provided at the tip of the support member 5. Therefore, the printing paper 1 is separated from the heat roll 2 together with the pressure roll 3 by a predetermined distance. As a result, it is possible to prevent a part of the printing paper 1 from being left in contact with the heat roll 2 for a long time. Therefore, it is possible to appropriately prevent a part of the printing paper 1 from locally yellowing due to overheating by the heat roll 2.

〔Example〕

Examples of the present invention will be described below. FIG. 1 is a side view showing an embodiment of the present invention, and FIG. 2 (a) is a side view showing a state where the pressure rollers are separated. In the figure, 1
Is a printing paper, 2 is a heat roll, 3 is a pressure roll, and both ends of a shaft 4 of the pressure roll are rotatably supported by support members 5. The support member 5 has one end rotatably supported by the shaft 6, is engaged with the projecting portion 8 ′ of the link plate 8 and is pulled by the spring 7 to each other. Further, the tip of the supporting member 5 is a printing paper guide portion 5'having a curved surface of a long arc surface.

The shaft 6 is supported by a frame (not shown), and the supporting members 5 are urged toward the heat roll 2 by springs 7, respectively, and press the pressure roll 3 against the heat roll 2 with a predetermined pressure contact force. There is. The pin 12 fitted on the movable shaft 11 ′ of the plunger magnet 11 is a lever
It engages with the elongated hole at the end of 10 and operates in the direction of the arrow shown when the plunger magnet 11 is turned on (at the time of attraction). 13 indicates a stopper. The other end of the lever 10 is connected to a cam follower 18 (Fig. 3) by a shaft 14. After the pressure roll 3 is separated from the heat roll 2, one end of the reset lever 16 for returning to the pressure contact state is fitted into the shaft 14, the plunger magnet 11 is turned on, the cam 17 is activated, and the roller 19 of the cam follower 18 is moved. By sliding on the cam surface, the reset lever 16 moves in the direction of the arrow in FIG. 3, and the central protruding piece 16 'of the reset lever 16 presses the end of the link plate 8 to restore it to its original position.

FIG. 1 shows a state in which the pressure roll 3 is in pressure contact with the heat roll 2, but when releasing the pressure contact of the pressure roll from this state, the plunger magnet 11 is turned off (released state) as shown in FIG. Since the lever 10 operates in the direction of the arrow, the link plate 8 moves counterclockwise until it hits the stopper 15 about the shaft 6 by the pulling force of the spring 9, and the support member 5 moves counterclockwise. The pressure roll 3 is separated from the heat roll 2 with a predetermined distance. At this time, the printing paper 1 is
The printing paper guide portion 5'having a long arcuate curved surface that abuts against the heat roll contact surface side pulls the print paper guide portion 5'in a direction away from the heat roll 2, so that it is separated from the heat roll 2 by a predetermined distance. FIG. 3 is a diagram for explaining the reset state. According to the present invention, a shaft is provided at one end of the cam follower 18 sliding on the reset cam surface.
It has a reset lever 16 connected to 14, and a protrusion 16 ′ is provided on a part of the reset lever 16. The cam 17 is actuated by the reset signal, and the cam follower 18 is actuated counterclockwise at the cam high position, whereby the reset lever 16 is actuated in the direction of the arrow and the projection 16 ′ pushes the end of the link plate 8. As a result, the end portion of the link plate 8 and the notch portion of the lever 10 are engaged with each other to be in the latched state, that is, the pressure roll 3 is the heat roll 2
Pressure contact.

According to the above embodiment, the plunger magnet 11, the lever 10, the reset lever 16, the link plate 8, the spring 7,
Since the support member 5 is automatically controlled to rotate by the automatic contacting / separating means including the reset cam 17, the reset cam 17, the cam follower 18, and the like, the pressure roll 3 automatically comes into contact with and separates from the heat roll 2. Become. That is, when the plunger magnet 11 is actuated based on various detection signals, the automatic contact / separation means operates so that the pressure roll 3 smoothly contacts and separates with respect to the heat roll 2. For this reason, the paper jam removing operation is facilitated, and the roller is not deformed or damaged, and the maintenance cycle can be extended. In particular, since the printing paper 1 is separated from the heat roll 2 by a predetermined distance at the same time as the separating operation of the pressure roll 3, there is an advantage that the yellowing of the printing paper 1 due to overheating of the heat roll 2 can be appropriately prevented.

〔The invention's effect〕

 According to the present invention, the following operational effects can be obtained.

(A) Automatic contact / separation means (plunger magnet 11, lever
10, reset lever 16, ring plate 8, springs 7,9,
(Including reset cam 17 and cam follower 18)
Since the support member 5 is automatically controlled to rotate, the pressure roll 3 automatically comes into contact with and separates from the heat roll 2. Therefore, it is possible to perform a paper jam removal operation and the like quickly and accurately.

(B) When the pressure roll 3 starts the separating operation from the heat roll 2 by the automatic contacting / separating means when the operation of the heat roll fixing device is stopped, the heat roll 2 until then.
Printing paper that should be heated and fixed against the surface of the paper 1
Is pulled in a direction away from the heat roll 2 by a printing paper guide portion 5 ′ provided at the tip of the support member 5. Therefore, the printing paper 1 is separated from the heat roll 2 together with the pressure roll 3 by a predetermined distance. As a result, it is possible to prevent a part of the printing paper 1 from being left in contact with the heat roll 2 for a long time. Therefore, it is possible to appropriately prevent a part of the printing paper 1 from locally yellowing due to overheating by the heat roll 2. Moreover, in this case, since the print paper guide portion 5'contacts the heat roll contact surface side in the fixed area of the print paper, the print surface may be rubbed by the guide portion 5'and may be soiled. There is no.

[Brief description of drawings]

FIG. 1 is a side view showing a configuration of a contacting / separating mechanism according to an embodiment of the present invention, and FIGS. 2A and 2B are side views showing a roll separating operation state of the contacting / separating mechanism according to the embodiment. And lever
FIG. 3 is an end view showing the relationship between 10 and 16, and FIG. 3 is a side view showing a roll reset operation state of the contact / separation mechanism according to the embodiment. FIG. 4 is an explanatory diagram of a conventional example. 1 ... Printing paper, 2 ... Heat roll, 3 ... Pressure roll, 5 ... Support member, 6 ... Shaft, 7 ... Spring, 8
...... Link plate, 10 …… Lever, 11 …… Plunger magnet, 16 …… Reset lever, 17 …… Reset cam, 18 …… Cam follower, 19 …… Roller.

Continuation of the front page (56) Reference JP 59-34575 (JP, A) JP 55-115071 (JP, A) JP 62-92979 (JP, A) JP 55-563 (JP , A) JP 56-168676 (JP, A) JP 59-34575 (JP, A) JP 57-124774 (JP, A) JP 57-89784 (JP, A) JP 61-84672 (JP, A) Actually opened 57-116963 (JP, U) Actually opened 58-52561 (JP, U) Actually opened 57-148159 (JP, U) Actually opened 57-23555 (JP, U) Japanese Patent Sho 61-4103 (JP, B2) Japanese Official Sho 58-46418 (JP, Y2)

Claims (1)

[Claims] 1. A heat roll rotatably provided, a pressure roll for pressing a print sheet to be heat-fixed onto the surface of the heat roll, and a pressure roll rotatably supported at an intermediate portion. A support member whose base end is rotatably supported; and means for automatically controlling the rotation of the support member to bring the pressure roll into and out of contact with the heat roll. The member contacts the heat roll contact surface side in the fixed region of the printing paper when the pressure roll is separated from the heat roll at the tip, and heats the printing paper with the separating operation of the pressure roll. A contact / separation mechanism for a heat roll fixing device, characterized in that it has a printing paper guide portion for separating it from the roll.