JPS5936275A - Fixation device of electrophotographic device - Google Patents

Abstract

PURPOSE:To obtain a pressing device with simple mechanism, by supporting a pressure roll at one end of a shaking lever through a compression spring, and moving the other end of the lever up and down and performing pressure application by a displacing device and performing pressure application and its releasing. CONSTITUTION:Arms 4 and 6 supported at fulcra (a) and (b) in shaking movably are linked together through the compression spring 5; the pressure roll 3 is supported on the arm 4 and the cam of the displacing device is provided to the arm 6. The cam 7 is rotated clockwise by a motor for the pressure application to press a step part 12 by a roll 8, and when a projection part C is detected by a sensor 13, the motor is stopped to press the roll 3 against a fixation roll 1 by the spring 5. The cam 7 is rotated counterclockwise by the same motor for the pressure releasing and a projection part (d) is detected by the sensor 13 to stop the motor. Consequently, the pressure application and releasing are carried out by the same motor to simplify the structure.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fixing device used in an image forming apparatus such as an electrophotographic apparatus or a recording machine.

Conventionally, in a fixing device that passes a copy paper between a pair of rollers and permanently fixes the toner image carried on the copy paper by pressure or pressure and heat, the pair of rollers is generally made of an elastic material. It is composed of a roller and a rigid roller, and by pressing this/pair of rollers, the copy paper passing between the rollers is pressed and the toner image is fixed.

Conventionally, there has been a method of applying pressure by pressing a pair of rollers against each other, and a method of removing the pressure by using an air cylinder, or a method of applying pressure by moving a cam using the driving force of a motor and connecting it to the shaft. There are methods to lock the pressurized state by locking with a pawl or ratchet, etc., and methods to release the pressurization by releasing the pawl or ratchet with a plunger etc., but in these devices, It is necessary to provide special pressure locking means, lock release means, etc., and when these means are used, as the machine becomes larger, the equipment necessary to achieve it also becomes larger. As a result, vibration and noise increase, causing problems.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a pressurizing device that presses and releases a pair of rollers by using a rotation limiting device attached to a drive source. That is, it is equipped with a simple locking device, and the pressurization value is used together with the pressurization removal and removal [IIt].

The invention will be explained below with reference to embodiments shown in the drawings.

Figure 1 Figure 1 and Figure 3 are one of the embodiments of the present invention,
FIG. 1 is a side view showing the constant 7M device in a pressurized state, FIG. 2 is a side view showing the pressurized state, and FIG. 7 is a perspective view of the drive system.

The metal fixed shield roller/has a halogen heater as a heat source inside, and is supported by a bearing (not shown) at the rotation port I.

The pressure roller 3 has an elastic body such as rubber on its outer periphery, and both ends thereof. It is rotatably supported by the arm via a bearing.

One end of the arm holder is held in a spherical spring seat pa, and the other end is a pressure spring j whose other end is held in a spherical spring seat 6a on the arm 6.
The arm 6 is connected to the arm tei and the arm t is connected to the fulcrum a.
and can swing around the fulcrum. 7 is a disk-shaped cam that can rotate around the shaft. cam 7
A roller g rotatable on a cam is provided at an offset position on the top. As shown in FIG. 7, the same cam is provided at the other end of the shaft.

The motor/θ rotates in the direction of the arrow in synchronization with the copy start signal, and at the same time the latch/θ is activated, such as an electromagnetic clutch.
/ is turned on, the drive of motor /θ is transmitted to gear /6 via clutch //, and gear 1 meshes with gear 16.
5 is turned, and the cams 7 at both ends on the shaft D to which the gear 15 is fixed rotate in the direction of the arrow.

At this time, the roller t rotates and presses the cam follower portion 6d of the arm B, and the arm 6 is rotated clockwise around the fulcrum. This movement of the arm 6 biases the arm holder around the fulcrum a through the spring 5, and moves the pressurized portion 3 supported by the arm holder in the direction of contacting the fixing roller.

The cam follower part Δd of arm B is provided with a step part /2, and at the same time when the roller t falls into the step part /2, a protrusion C part is provided at a position synchronized with it to detect the cam 70 position 1a. Sensor /3 detects this, and the motor 10 and clutch /l are turned off in response to the signal.

As shown in Fig. 3, which is a partially enlarged view of Fig. 2, the stop position of this roller is shifted about 50 degrees beyond the bottom dead center, and due to the compression of the spring S, it is always opposite to the rotating direction of the cam. A force in the direction is applied to bring the roller t into a stable state in the position where it is pressed against the stepped portion. This is the state where the pressure is completed and the pressure roller 3 is a spring! is pressed against the fixing roller with a constant pressure. This is the pressurized state shown in Figure 1. Although a latch/l is not an essential requirement like an electromagnetic clutch, since the motor has inertia, it immediately cuts off the drive and acts as a buffer against the locking mechanism.

Next, the operation when pressurization is released will be described.

When the copying is completed, the motor /θ and the clutch // are energized again, and the camshaft is rotated from the state shown in Fig. 2 in the direction of the arrow opposite to that when pressurized, the roller g passes the bottom dead center, and then the 1 As shown in figure 1, the protrusion dy sensor on the cam
3 is detected, the motor 10 and the clutch are turned off by the signal, and the cam 7 stops rotating.

Before it stops, the other end of the arm B, which is pressed by the spring 5, comes into contact with the fixed stop collar, and is stopped and held there.
: I refuse.

This completes the release of pressurization and returns to the release state shown in FIG. 1 again.

In special cases, if the power is turned off during copying, that is, during pressure lock, for example, in the event of a power outage, electricity is stored in a current-carrying capacitor, etc., and discharged by a power-off signal to rotate the motor 10. , rotate the motor/θ to release the pressure. Kamuk is the worst on the upper side! The capacitor does not need to be very sensitive as it is sufficient to rotate the 0+ shaft D and rollers by a friction angle equivalent to the rolling friction angle or more.

This drawing is a partial side view of still another embodiment of the present invention, except as shown in the drawings. - Same as figure. Arm/L, which corresponds to Arm B, has a step/Y at its tip (protrusion 2 is provided). When pressurized in the direction of arrow e and stopping rotation at a position approximately 5 degrees beyond the bottom dead center, Arm/L It is locked at stage i/λ of
? This is done by reverse rotation, that is, by rotating in the direction of arrow f.

As described above, the present invention provides a fixing device in which one of a pair of rollers is movably supported by a swinging lever, and the other roller is caused to swing the lever by a biasing device to press a pair of rows 2- into contact with each other. , the biasing device is actuated in one direction by the same driving source, and has the function of pressuring a pair of rollers and maintaining that state, as well as the function of releasing the holding state, and a simple mechanism allows pressure to be applied. It becomes possible to maintain the state and release the pressurized state.

[Brief explanation of the drawing]

FIG. 1 is a side view of the fixing device when pressure is released to which an embodiment of the present invention is applied, FIG. 1 is a side view of the fixing device when the fixing device is pressurized, and FIG. FIG. 1 is a perspective view of the fixing device when pressurized, and FIG. S is another embodiment 1 of the present invention.
It is P −−2′. /... Fixing roller λ - Halogen heater 3... Pressure roller See 4 ψ arm S... Spring 6... Arm 7... Cam gII/ Roller... 44h 10
--Motor //Gi clutch /Roller/Step part/3
...Sensor/Koken/Stopper 1g,/l--Gear/7...Clutch/To...Lever abe/Fulcrum (
, d m a protrusion +a, Aa-so spherical spring seat Ad
...Cam follower. Special Note Applicant Canon Co., Ltd. Agent Arai - Department C 1; Figure 1 Figure 2

Claims (1)

[Claims] In a fixing device that fixes an unfixed toner image on a transfer material by passing the transfer material between a pair of rollers, the roller receives the driving force of the motor to apply pressure between the motor and the roller. a row 2 displacement means for displacing; a locking means for locking the displacement means in a roller pressurized state;
A fixing device comprising: a release means for releasing the lock of the locking means by driving the motor.