JPS6220848Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of a paper feeding mechanism of a developing and fixing device in a copying machine, a facsimile machine, etc.

The paper feeding mechanism of this type of apparatus is generally provided with a feeding roller, a developing device, and a fixing device in the feeding direction of the recording paper, and the recording paper is sequentially fed by the feeding roller. In such a paper feeding mechanism, the developing device is a powder developing device, and the fixing device is a pressure fixing device consisting of a pair of rollers pressed together with strong force, and the distance between the feeding roller and the pressure fixing roller is When conveying a much longer recording paper, the recording paper may become loose between the feed roller and the pressure fixing roller due to an error in the feeding speed between the feed roller and the pressure fixing roller, an error in the parallelism of the axes between the feed roller and the pressure fixing roller, etc. Not only is there a possibility that wrinkles may occur, but there is also the problem that wrinkles may occur due to changes in the conveying direction by the pressure fixing roller due to the deviation of the recorded image in the width direction of the recording paper.

FIG. 1 shows the paper feeding mechanism in such a developing and fixing device.
1b is a feed roller, 12a and 12b are pressure fixing rollers (hereinafter referred to as pressure rollers), 13 is a feed guide, and 14 is a powder developing device. The developing device 14 includes a toner tank 14 ₁ , a magnet roll 14 ₂ , a sleeve 14 ₃ and the like. Such a developing/fixing device is a feed roller 11.
The toner is transferred (developed) onto the recording paper 15 sent by the magnet rolls 142 and 11b by the action of the magnet roll ₁₄₂ and the sleeve ₁₄₃ , and then fixed under pressure by the pressure rollers 12a and 12b. It is.

Therefore, in the developing/fixing device as described above, if the recording paper 15 is much longer than the distance between the feed rollers 11a, 11b and the pressure rollers 12a, 12b, the recording paper 15 can be moved by two rollers at the same time. At this time, if there is an error in the feed speed of the two roller pairs or an error in the parallelism of the axes of the roller pairs, the recording paper 15 will be subjected to a feeding force, and wrinkles will occur. Good development cannot be carried out in these areas, which not only causes deterioration in development quality, but also causes these wrinkles to be crushed by the pressure fixing roller, making the image impossible to read, and only the wrinkled areas are subjected to strong pressure. This has caused poor fixation in other areas, which has been a bigger problem than in the past.

Furthermore, even if the speed error and parallelism error mentioned above are minimized, if the recorded image is offset in the width direction of the recording paper, the pressure applied to the recording paper between the pressure fixing rollers will cause the recorded image to be offset. As a result, the direction in which the recording paper is conveyed by the pressure fixing roller is biased toward the direction where the pressure is weaker, causing wrinkles, which is a big problem similar to the above.

This idea was made in view of the above points, and is a developing and fixing device that does not cause wrinkles between the rollers even when using recording paper that is much longer than the distance between the feed roller and the pressure fixing roller. The purpose is to provide a paper feeding mechanism.

An embodiment of this invention will be described below with reference to the drawings. FIG. 2 is for explaining the basic operation of this invention, and 21a and 21b are feed rollers,
22a and 22b are pressure fixing rollers (hereinafter referred to as pressure rollers); 23 is a developing device consisting of a developing roller 23 ¹ and a toner tank 23 ₂ ; 24 is a recording paper; 25 is a guide portion that guides the feeding of the recording paper 24; 26 is a recording paper detector that detects the leading edge 24a of the recording paper 24 that has passed through the pressure rollers 22a and 22b; 27 is a control circuit into which the detection signal of the recording paper detector 26 is input; and 28 is a signal from the control circuit 27. This is a plunger that is driven by a plunger and pulls up the feed roller 21a of the feed rollers 21a and 21b in the direction of arrow A. The recording paper detector 26 may be a micro switch or a photoelectric conversion element, and various detection means may be used.

In such a configuration, the leading edge 24a of the recording paper 2
When the paper passes through the pressure rollers 22a and 22b, the recording paper detector 26 detects it and sends the detection signal to the control circuit 27. This drives the plunger 28 and moves the feed roller 21a upward (in the direction of arrow A).
be lifted up. Therefore, the recording paper 24 is guided by the guide portion 25 and slides onto the toner layer formed on the developing roller ₂₃₁ while moving onto the pressure roller 22.
Since it is sent by the feeding force of only a and 22b,
No wrinkles are formed between the pressure rollers 22a, 22b, the developing roller ₂₃₁ , and the feed rollers 21a, 21b.

Next, the plunger 2 described above according to FIGS.
8 will be described in detail. 3a and 3b specifically show the portion shown by the dashed dot line in FIG. 2, and the same parts are given the same reference numerals. In FIGS. 3a and 3b, 31 is a side plate, and feed rollers 21a and 21b are rotatably attached to this side plate 31. That is, the feed roller 21b is rotatably supported by a shaft 32 on the side plate 31, and the feed roller 21a is slidable up and down by inserting its shaft 34 into a U-shaped notch 33 formed in the side plate 31. Rotatably supported. A substantially central portion of an elongated spring 36 whose both ends are hooked to pins 35 ₁ and 35 ₂ is spanned over the shaft 34 of the feed roller 21a. The pins 35 ₁ and 35 ₂ are provided to protrude from the side plate 31, and their protruding positions are below the shaft 34.
As a result, a force in the direction of arrow B is always applied to the shaft 34, and under normal conditions, the feed roller 21a and the feed roller 21
b is in pressure contact. Further, a tip end 37a of a lever 37 is in contact with the lower portion of the shaft 34. The lever 37 is rotatably attached to the side plate 31 by a shaft 38 at its midpoint, and its rear end 37b is pivotally supported by the actuator 28a of the plunger 28.
This plunger 28 is fixed to the side plate 31, and the second
It is electrically connected to the control circuit 27 shown in the figure. During operation (excitation), the plunger 28 attracts the actuator 28a in the direction of arrow C, so that the tip 37a of the lever 37 rotates in the direction of arrow D.

With the above configuration, the pressure roller 22a,
When the leading edge 24a of the recording paper 24 that has passed through the recording paper 22b is detected by the recording paper detector 26, the plunger 28 is driven by the control circuit 27 as described above.
This causes the plunger 28 to operate its actuator 28a.
In order to attract the liquid, the tip end 37a of the lever 37 rotates in the direction of arrow D using the shaft 38 as a fulcrum. The tip end 37a of this lever 37 is connected to the feed roller 21a.
Since the shaft 34 is in contact with the lower part of the shaft 34, the shaft 34 is pushed upward in the notch groove 33 of the side plate 31 against the biasing force of the spring 36. As a result, the feed roller 21a separates from the feed roller 21b, so that the recording paper 24 is not fed by the pressure rollers 22a, 22a.
This is done only by b. Therefore, pressure roller 2
The recording paper 24 is no longer wrinkled between the feed rollers 2a, 22b and the feed rollers 21a, 21b.

As explained above, according to the present invention, when the leading edge of the recording paper fed by the feed roller passes the pressure fixing roller, this is detected and the pair of rollers of the feed roller are separated. To provide a paper feeding mechanism capable of performing inexpensive and high-quality development and pressure fixing without causing wrinkles between the rollers even when the recording paper is much longer than the distance between the feeding roller and the pressure fixing roller. Can be done.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram showing an outline of the developing/fixing device;
FIG. 2 is an overall schematic diagram for explaining an embodiment of this invention, and FIG. 3 is a diagram for explaining the main part of the embodiment in detail. 21a, 21b...Feed roller, 22a, 22
b...Pressure roller, 23...Developing device, 24...
Recording paper, 26... Recording paper detector, 27... Control circuit, 28... Plunger, 31... Side plate, 36...
...Spring, 37...Lever.

Claims (1)

[Scope of utility model registration request] A feed roller, a powder developing device, and a pressure fixing roller are arranged in order in the conveyance direction of the recording paper, and a distance between the feed roller and the pressure fixation roller is set to be shorter than the length of the recording paper in the conveyance direction. In the paper feeding mechanism of the developing and fixing device, the recording paper feeding guide section is provided opposite to the developing roller of the powder developing device, and the leading edge of the recording paper fed by the feeding roller touches the pressure fixing roller. A paper feeding mechanism characterized in that a pair of rollers constituting the feeding roller is separated by detecting that the paper has passed.