JP2576192B2 - Buffer mechanism for electrophotographic equipment - Google Patents

Description

The present invention relates to a buffer mechanism of an electrophotographic apparatus.

[Background of the Invention]

2. Description of the Related Art In an electrophotographic apparatus that transfers and fixes a toner image formed on a photoreceptor onto a continuous printing paper and performs printing, a tractor mechanism that normally transports the printing paper to a transfer position as a paper feeding mechanism and a transfer to the printing paper are used. And a fixing roll mechanism for fixing the unfixed toner image thus formed. By controlling the driving of the tractor mechanism and the fixing roll mechanism with a servomotor or the like, the printing paper conveyed over the paper feeding mechanism is conveyed. I have.

In the case of an electrophotographic apparatus having the above-described paper feed mechanism, the printing paper being conveyed may be slackened or excessively stretched due to fluctuations in the paper feeding speed of the paper feeding means. Correct the amount
Conventionally, a buffer mechanism has been provided between the tractor mechanism and the fixing roll mechanism for the purpose of maintaining stable paper conveyance.

Paper slack is likely to occur especially when the paper feed mechanism is started or stopped.This is because the magnitude of the moment of inertia around the motor between the tractor mechanism and the fixing roll mechanism is different, and both reach a constant paper feed speed. The time required before the printing is different, and this time difference leads to a speed difference between the sheet feeding mechanisms, and as a result, the speed difference causes a sheet slack or the like.

The buffer mechanism of the conventional electrophotographic apparatus has a configuration in which an elastic member such as a spring is engaged with a buffer plate constituting the buffer mechanism, and only the upper surface of the buffer plate is pressed against the lower surface of the printing paper. When paper slack occurs, the buffer plate suddenly collides with the printing paper with kinetic energy due to the vibration caused by the restoration (elongation) and compression of the elastic member, and when the vibration of the buffer plate continues, the printing paper runs. Is not stable, and the running state of the paper is unstable, resulting in problems such as poor transfer (transfer deviation) and scattering of an unfixed toner image on printing paper (image blurring).

[Object of the invention]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and to eliminate printing defects due to speed fluctuations of a paper feed mechanism.

[Summary of the Invention]

In order to achieve the above object, in the present invention, the buffer mechanism is provided with a kinetic energy absorbing mechanism that absorbs an impact force exerted on the buffer plate by the printing paper being transported.

(Example of the invention)

FIG. 1 shows the configuration of an electrophotographic apparatus to which the buffer mechanism of the present invention is applied.

In the figure, an electrostatic latent image is formed on a photoreceptor 2 whose surface is uniformly charged by a charger 1 by a laser beam 3 or the like emitted from an exposure device (not shown). Are developed by the developing device 4 and visualized. The developed image formed on the surface of the photoconductor 2 in this manner is transferred to the printing paper 6 side by the suction action of the transfer unit 5, sent to the fixing roll mechanism 8 via the preheating plate 9, and is fixed to the fixing roll mechanism 8. The fixing is performed on the printing paper 6 by the heating and pressurizing action of 8.

A buffer mechanism 10 provided between the tractor mechanism 7 and the fixing roll mechanism 8 constituting the paper feed mechanism is provided on a frame 18 supporting the tractor mechanism 7 as shown in FIG. With the shaft 12,
A buffer plate 11 rotatably provided around the shaft 12 as a rotation axis, and a spring member 13 provided in engagement with the buffer plate 11 and the shaft 12 so as to regulate the buffer plate 11 to a fixed inclination angle, When an external force acts on the buffer plate 11, the external force
It is composed of a kinetic energy absorbing mechanism that absorbs the impact force brought to 11. The kinetic energy absorbing mechanism is configured as a shock absorber utilizing frictional resistance and viscous resistance.

In the present embodiment, a case in which a kinetic energy absorbing mechanism using frictional resistance is taken up and the transport energy absorbing mechanism is configured as a rotary brake device will be exemplified. Less than,
The configuration of the rotary brake device will be described with reference to FIG.

The rotary brake device 14 includes a one-way clutch 16 fitted to a shaft 12 that constitutes a rotation axis of the buffer plate 11.
And a brake ring 15 provided so as to cover the outer periphery of the one-way clutch 16, and a screw 17 for adjusting a tightening force of the brake ring 15 with respect to the one-way clutch 16. As shown in FIG. 2, two (14a, 14b) are provided.
The brake ring 15 is formed of resin or the like because a frictional force is generated on the outer peripheral surface of the one-way clutch 16 as described later.

In the rotary brake device 14a and the rotary brake device 14b, the rotation directions of the one-way clutch 16 are different, so that different braking forces are applied to the rotation direction of the buffer plate 11 due to the difference between the tightening forces of the screws 17a and 17b. , And the braking force absorbs the impact force on the buffer plate 11. For example, the rotation direction of the one-way clutch provided on the rotary brake 14a is provided so as to be clockwise in FIG. 3, and the rotation direction of the one-way clutch provided on the rotary brake device 14b is provided so as to be counterclockwise. When the buffer plate 11 rotates in the direction of arrow a, the shaft 12
Tries to rotate in the counterclockwise direction by the one-way clutch provided on the rotary brake device 14b, but the rotation direction is opposite to the one-way clutch provided on the rotary brake device 14a. The rotation of the one-way clutch and the inner surface of the brake ring 15 is generated while frictional resistance is generated between the outer surface of the one-way clutch and the inner surface of the brake ring 15 while preventing the rotation of the 11.

When the buffer plate 11 rotates in the direction of the arrow b, the relationship is opposite to that of the previous case, and a frictional resistance is generated between the outer peripheral surface of the one-way clutch provided on the rotary brake device 14b and the inner surface of the brake ring. Becomes

As described above, as a result of providing the kinetic energy absorbing mechanism for absorbing the impact force exerted on the buffer plate in the buffer mechanism of the electrophotographic apparatus, as shown in FIG.
^{= 4 × 10 5 g · cm} 2 / s 2 or more at which was to a ^{4 × 10 5 g · cm 2} / s 2
The buffer plate vibrates for a long time as in the prior art even if the printing paper being transported becomes slack due to speed fluctuations when the paper feed mechanism is started or stopped. As a result, stable paper conveyance can be maintained, and good printing with almost no character blurring in print quality has been realized.

The buffer plate 11 may be made of plastic, or a notch 19 may be formed on the surface of the buffer plate 11, that is, a sheet-facing surface of the buffer plate 11 as shown by a broken line in FIG. 2 to reduce the weight of the buffer plate. As a result, the collision energy of the buffer was about 0.5 × 10 ⁵ gcm ²
/ s ² was greatly reduced.

〔The invention's effect〕

According to the present invention, since the kinetic energy absorbing mechanism for absorbing the impact force applied to the buffer plate is provided, even if the printing paper being conveyed is slackened due to the speed fluctuation of the paper feeding mechanism, almost no character blurring or the like occurs. Stable paper conveyance that does not occur can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a configuration of an electrophotographic apparatus to which the present invention is applied, FIG. 2 is a perspective view of a main part of a buffer mechanism according to the present invention, and FIG. 3 is a main part of a buffer mechanism according to the present invention. FIG. 4 is a sectional view showing the relationship between the character blur amount and the collision energy of the buffer. In the figure, 11 is a buffer plate, 12 is a shaft, 13
Denotes a spring member, and 14 denotes a rotary brake device.

Claims (8)

(57) [Claims] A transfer unit configured to transfer a developed image formed on a photoreceptor to a sheet; a tractor mechanism provided upstream and downstream of the transfer unit in a sheet conveying direction; A fixing roll mechanism for fixing an image, provided between the tractor mechanism and the fixing roll mechanism,
An electrophotographic apparatus having a buffer mechanism provided with a buffer plate rotatably supported with respect to the surface of continuous printing paper conveyed between the tractor mechanism and the fixing roll mechanism. A buffer mechanism for an electrophotographic apparatus, further comprising a kinetic energy absorbing mechanism for absorbing an impact force exerted by the printing paper on the buffer plate. 2. A buffer mechanism for an electrophotographic apparatus according to claim 1, wherein said kinetic energy absorbing mechanism comprises a buffer for absorbing kinetic energy of said buffer plate by frictional force. 3. The electrophotographic apparatus according to claim 1, wherein said kinetic energy absorbing mechanism is configured as a rotary brake device provided on a rotary shaft of said buffer plate. Buffer mechanism. 4. The rotary brake device is mounted on the outer circumference of a plurality of one-way clutches provided on a rotation shaft of the buffer plate and having different rotation directions. 4. A buffer mechanism for an electrophotographic apparatus according to claim 3, wherein an arbitrary frictional force is given to the buffer, and the kinetic energy of the buffer is absorbed by the frictional force. 5. The electrophotographic apparatus according to claim 3, wherein a brake ring of a tight ring type using a static friction force by a tightening torque is used as said rotary brake device. Buffer mechanism. 6. A buffer mechanism for an electrophotographic apparatus according to claim 1, wherein said buffer plate is formed of plastic. 7. A method according to claim 1, wherein a cutout portion is formed on a surface of said buffer plate facing said sheet.
Item 7. A buffer mechanism for an electrophotographic apparatus according to Item 2, Item 3, Item 3, Item 4, or Item 6. 8. The apparatus according to claim 1, wherein said kinetic energy absorbing mechanism is a mechanism for reducing the kinetic energy of said buffer mechanism to 4 × 10 ⁵ g · cm ² / s ² or less. Buffer mechanism for electrophotographic equipment.