JPH053501Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to an automatic duplex paper feeding device in an image forming apparatus such as a copying machine or a printing device using an electrophotographic method.

Prior Art FIG. 1 shows a schematic configuration diagram of a copying machine that is an example of an image forming apparatus and is capable of double-sided copying.

A developed image is formed on the photoreceptor drum 1 by a well-known exposure and development process, and the transfer paper onto which this developed image is transferred is fixed through the fixing device 2 and used as copy paper. The paper is discharged from the discharge roller 3 in the direction of arrow B.

In the figure, an automatic duplex paper feed unit 4 is provided at the lower left of the copying machine, and a duplex paper feed section 5 of this unit stores copy paper that has been ejected from the ejection roller 3 and has undergone single-sided copying. Incidentally, the copy paper discharged from the discharge roller 3 is designed to have electricity removed by a electricity removal brush 6.

As shown in FIG.
0, a paper feed roller 12, a friction separation member 13, etc. The front roller 10 has a shaft 14
The shaft is mounted on the free end of a swinging rod 15 which is pivotally connected to the shaft, and is rotationally driven by a belt 16. The pair of joggers 8 are driven by the rotation of the motor 17 in the direction of the arrow depending on the size of the copy paper.

Normally, the bottom plate 9 is placed in a horizontal position as shown in FIG.
0 falls onto the copy paper, and the copy paper is moved over the double-sided paper feed tray 7 and the bottom plate 9 by the rotation of the front roller, and its leading edge is brought into contact with the front plate 18.

Each time a copy paper is ejected one by one, the swinging rod 15 (FIG. 2) swings and the forwarding roller 10 falls, bringing the copy paper one by one to the side of the front plate 18. Align the leading edge of each piece of copy paper.

When all the copy sheets are stored in the double-sided paper feed section 5, the bottom plate 9, which had been placed in a horizontal position, swings to an inclined position as shown by the solid line in FIG. In this inclined state, the leading edge of the copy paper is pressed against the paper feed roller 12. In this state, the copy paper is fed again one by one from the top to the copying section such as the photoreceptor and fixing device by the cooperation of the paper feed roller 12 and the frictional separation member 13, and the other side is copied and discharged in the direction of arrow A in FIG. As a result, double-sided copy paper is obtained.

Here, the amount of rotation of the forwarding roller 10 when moving the copy paper toward the front plate 18 is determined from the position where the copy paper falls to the front plate in order to ensure that the copy paper hits the front plate 18. The amount of rotation is set so that the amount of rotation is a little longer than the distance up to 18, so as to prevent insufficient close-up.

Furthermore, after the copy paper hits the front plate 18,
Due to the stiffness of the copy paper, the forwarding roller 10 is caused to slip between the copy paper and the copy paper. When a predetermined number of copy papers are stacked on the double-sided paper feed table 7, the bottom plate 9 is tilted as described above, and at this time, the leading edge of the copy paper is brought into contact with the paper feed roller 12 with a predetermined pressure. .

In this case, if the copy paper is normally gathered as shown in FIG. 5a, the copy paper will be fed correctly in the next paper feeding process, and double-sided copy paper will be automatically obtained.

However, as shown in FIG. 5b, if the alignment is not done properly, the bottom plate 9 will rise along the front plate 18, so the free end of the bottom plate 9 and the front plate 18 will If the leading edge of the copy paper gets stuck in the gap, a paper feeding failure will occur the next time the paper is fed. In addition, even if it does not fit between the front plate and the front plate, the upper copy paper may become wedged between the leading edge of the lowest copy paper and the front plate 18, resulting in a similar paper feeding failure. will occur.

By the way, the transfer paper that has been transferred is transferred to the fixing device 2.
(Fig. 1), the copy paper shows Fig. 5 b.
There is a tendency for curling as shown in the figure below.
If such a curl is large, the leading end of the sheet tends to bend between the bottom plate 9 and the front plate 18, resulting in the paper feeding failure as described above.

By the way, in FIG. 1, it has already been mentioned that when the copy paper is discharged from the discharge roller 3, the charge is removed from the copy paper by the charge removal brush 6, but this charge removal cannot be said to be complete, and the copy paper is In some cases, the paper may still be charged with static electricity.

If the amount of static electricity is large, the copy papers will stick to each other when they are brought together by the advance roller 10, and the rotational frictional force of the advance roller will cause a slip between the roller and the copy paper. This may occur, making it impossible to stack the copy paper.

If the copy paper cannot be gathered together, the leading edge of the copy paper cannot be aligned, and the leading edge of the copy paper may not come into contact with the paper feed roller 12, which may result in paper feeding failure. Paper feeding failures due to such causes occur even when paper has a small amount of static electricity but a very large coefficient of friction.

Therefore, as a countermeasure against this problem, it is possible to increase the contact pressure of the front-feeding roller 10 against the copy paper to increase its feeding force. For copy paper or copy paper that has a large amount of curl due to the above-mentioned reasons, the pushing force by the front shifting roller is too strong, so even if the leading edge of the copy paper hits the front plate 18, As shown, the paper may get stuck between the bottom plate 9 and the front plate 18, or it may get wedged between the leading edge of the lowest copy paper and the front plate 18, resulting in paper feeding failure.

Purpose The purpose of the present invention is to prevent the above-mentioned paper feeding failure from occurring and to realize it at low cost.

Configuration In order to achieve the above object, the present invention includes a double-sided paper feed tray that accommodates single-sided copy paper ejected one by one, and a double-sided paper feed tray that can freely approach and separate from the double-sided paper feed tray, Align the copy paper on the paper stand one by one,
a front-shifting roller for aligning the leading edge thereof; a solenoid for driving the front-shifting roller in a direction to separate it from a duplex paper feed tray; and a solenoid for driving the front-shift roller in a direction to bring it into contact with the copy paper on the duplex paper feed tray; The apparatus is characterized by comprising a spring whose elasticity can be adjusted so that the spring elasticity works when the solenoid is energized and the spring elasticity does not work when the forwarding roller contacts the copy paper. It is.

The present invention will be explained below based on one embodiment.

In FIG. 6, the forwarding roller 10 is rotationally driven by a drive transmission system consisting of a chain 25, a sprocket 26, a belt 16, and the like. Swinging rod 1
A pin 27 is provided on the branch arm 15a on the proximal end side of 5, and a solenoid 28 is connected to this pin 27. This solenoid 28 is connected to the front roller 10.
is driven in a direction to separate it from the duplex paper feed table 7.
That is, when the solenoid 28 is energized, the swinging rod 15 is rotated clockwise around the shaft 14 in FIG. 4, and the forwarding roller 10 is moved upwardly. Note that the reference numeral 29 in FIG. 6 is a long hole for guiding the pin 27 provided on the side plate of the unit.

As shown in FIG. 7, an arm rod 31 is pivotally attached to the shaft 36, and a compressible spring 33 is hung between the rising arm portion 31a and the movement adjustment plate 32. The movement adjusting plate 32 can be adjusted to move in the directions of arrows a and b by loosening a screw 35 with respect to a mounting member 34 held in an immovable state. A notch as shown in the figure is provided at the arm end of the branch arm 31b of the arm rod 31, and the pin 27 is fitted into this notch.

When the solenoid 28 is energized, the front roller is spaced above the copy paper on the double-sided paper feed tray 7, as described above. At this time,
The spring 33 has been expanded by a predetermined amount and is in a state where elasticity is acting. In this state, when the excitation of the solenoid 28 is released (hereinafter referred to as OFF), the arm rod 31 is rotated due to its elasticity, and at the same time, the swing rod 15 is rotated. The forwarding roller 10 abuts on the copy paper.

Now, if the solenoid 28 is energized (hereinafter referred to as on), the forwarding roller 1
If the method is to lower the roller 0, the excitation force of the solenoid acts to force the roller 10 into strong contact with the copy paper, resulting in an excessively strong pulling force on the copy paper as described above, resulting in paper feeding failure. From this point of view, when the solenoid is turned on, roller 1
0 are separated from each other, and a spring 33 is applied to lower the roller 10 when the roller 10 is off.

However, if this is done, the forwarding roller 10
When the paper is lowered, the residual magnetism of the solenoid 28 slows down its lowering speed, shortening the actual front-loading time, resulting in insufficient front-loading of the copy paper. Such problems become more prominent as the speed of the copying machine increases, as the on-off time of the solenoid becomes shorter and residual magnetism is more likely to occur.

Here, in FIG. 9, the broken line indicates the lowered position when the front roller 10 falls onto the bottom plate 9, the two-dot chain line indicates the position when the roller 10 is on the copy paper at the maximum height, and the solid line indicates the position when the roller 10 is on the copy paper at the maximum height. indicate the upper limit position when the roller 10 separates from the copy paper.

Now, in FIG. 7, when the screw 35 is loosened and the movement adjustment plate 32 is moved in the direction of arrow a, the elasticity of the spring 33 is adjusted to a state where the tightening elasticity is weakened.

This elasticity overcomes the residual magnetism when the on solenoid 33 is turned off, and the roller 10
is set to such a degree that it falls.

FIG. 8 shows the relationship between the position of the forwarding roller 10 and the spring pressure. For example, line E is a line of change in the spring pressure when the movement adjustment plate 32 is moved in the direction of arrow a. After the forwarding roller 10 has descended to near the maximum height position of the copy paper, the spring pressure is set to zero. That is, the movement adjustment plate 32 is moved to a position that satisfies the above conditions. Hereinafter, such a state will be referred to as "spring pressure reduction mode." In such a mode, the front shifting roller 10 is brought into contact with the copy paper by the weight of the front shifting roller 10, the swinging rod 15, etc.

In contrast, the movement adjustment plate 32 in FIG.
When the spring 33 is moved in this direction, the elasticity of the spring 33 is adjusted to a state where the tightening elasticity is strengthened. For example, when the elasticity is set to the maximum, the forwarding roller 10
However, as shown in line F in Figure 8, even when it is in the lowered position, the spring elasticity works to bring forward copy paper with a large amount of static electricity or copy paper with a large coefficient of friction. Sufficient contact force can be obtained.

On the other hand, as mentioned above, when in the spring pressure reduction mode, it is possible to cope with copy paper that has a small amount of static electricity or has a weak stiffness, and at this time, the residual magnetism of the solenoid Since the roller 10 can be quickly lowered by overcoming this, sufficient time can be taken for the front movement.

As described above, by adjusting the movement of the movement adjustment plate 32 according to the destination of the image forming apparatus,
To smoothly and reliably refeed copy paper to a copying section in accordance with the type of copy paper. Moreover, since it is sufficient to provide only the movement adjustment plate 32, the spring 33, the arm rod 31, etc., the above-mentioned functions can be realized at relatively low cost.

Effects As described above, according to the present invention, regardless of the specifications of the copy paper, it can be smoothly and reliably re-fed to the copying section, and this can be achieved at a relatively low cost.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a copying machine that is an application example of the present invention, Fig. 2 is a perspective view showing the structure of a duplex paper feed section, and Fig. 3 explains the movement of copy paper in the duplex paper feed section. Figure 4 is a diagram to explain that the copy paper has become malfunctioning in the duplex paper feed section, and Figures 5 a and b are diagrams to explain whether the copy paper has been placed correctly on the duplex paper feed tray. FIG. 6 is a perspective view showing an example of a vertical drive mechanism for the front roller; FIG. 7 is a perspective view of the vertical drive mechanism for the front roller including a spring pressure adjustment means; FIG. This figure is a diagram for explaining the above-mentioned spring pressure adjustment method, and FIG. 9 is a diagram for explaining the positional relationship of the forwarding rollers. 7...Double-sided paper feed stand, 10...Front feed roller, 2
8... Solenoid, 33... Spring.

Claims (1)

[Scope of utility model registration request] A double-sided paper feed stand that accommodates single-sided copy paper discharged one sheet at a time, and a double-sided paper feed stand that can freely approach and separate from the duplex paper feed stand, and when in contact, the copy paper on the duplex paper feed stand is brought together sheet by sheet. , a front-shifting roller for aligning the leading edges thereof, a solenoid for driving the front-shifting roller in a direction to separate it from a duplex paper feed tray, and a solenoid for driving the front-shift roller in a direction to bring it into contact with the copy paper on the duplex paper feed tray. and a spring whose elasticity can be adjusted so that the spring elasticity acts when the solenoid is energized and does not act when the forwarding roller contacts the copy paper. Automatic duplex paper feeder.