JPH047220A - Paper feeder for image forming device - Google Patents

Abstract

PURPOSE:To prevent double feed by providing a pressing member, which increases a spring pressure of a tensile spring, in a side plate part of a paper feed cassette, which receives a paper sheet of size, applying weak lifting force to a mounting plate, in a paper feeder for an electrostatic photograph copying machine or the like. CONSTITUTION:A pressing member (b) is provided in line with a front part side upper end part of a side plate part 2a in both side in a width direction of a paper feed cassette 2 of performing a lateral feed of small size paper sheets (a) such as A-4, B-5. Then, a spring pressure of a tensile spring 24 is increased by attaching the pressing member (b) of the paper feed cassette 2 to an elliptic operating member 22, according to a paper feed cassette charging part 4 charged with the paper feed cassette 2, to move and rotate the operating member 22. In this way, double feed of paper sheets can be surely prevented by obtaining proper paper feed force even when weight of the paper sheet is changed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a paper feeding device installed in an image forming apparatus such as an electrostatographic copying machine or a digital original reading device.

[Conventional technology]

As shown in FIG. 7, the above-mentioned paper feeding device is a paper feeder that feeds the paper a from the paper cassette 41 into a paper cassette loading section 42 for removably loading the paper cassette 41. A roller 43 and a double-feed prevention means 44 for preventing double-feeding of sheets a by the paper feed roller 43 are provided, and the paper feed roller 43 prevents sheets from being loaded in the paper feed cassette slot 41 loaded in the paper feed cassette loading section 42. Some devices are provided with mounting plate pushing means 46 for pushing up the plate 45 toward the paper feed roller 43 side.

The mounting plate pushing up means 46 includes a mounting plate pushing up member 49 that is swingable around a support shaft 48 that is parallel to the rotating shaft 47 of the paper feed roller 43, and a mounting plate pushing up member 49 that moves the mounting plate pushing up member 49 to the paper feeding roller 43. It is configured such that the uppermost paper a in the paper feed cassette 41 is brought into pressure contact with the paper feed roller 43 via the paper loading plate 45.

On the other hand, the double feeding prevention means 44 is a crank-shaped arm 5.
1 is rotatably mounted on the bracket 53 around the horizontal axis 52, a friction pad 54 is attached to the upper end side of the crank-shaped arm 51, and a tension spring biases the friction pad 54 against the paper feed roller 43. 55 is provided across the lower end side of the crank-shaped arm 51 and the bracket 53.

Incidentally, the spring pressure of the tension spring 50 acting on the paper mounting plate 45 is proportional to the stacked thickness of the sheets a placed on the paper mounting plate 45, and The pressure applied to the sheet 43 is calculated by subtracting the weight of the sheet a on the sheet loading plate 45 from the spring pressure proportional to the stacked thickness of the sheet a. Frequently used paper a is A-3, A-
Standard sizes such as 4, 8-4, and 8-5 are common, and for small size paper a such as A-4 and 8-5, the short direction of paper a is fed. The paper feeding mode is horizontal feeding in which the sheet is oriented in the direction of paper feeding, and a feeding form in which the paper is feeding vertically in the direction in which the longitudinal direction of paper a is oriented in the feeding direction is selected, as is the case with large-sized paper a such as A-3 and B-4. Ru.

[Problem to be solved by the invention]

When a small size paper a, which is light in weight, is fed vertically, the trailing edge of the paper a comes off the paper loading plate 45 and is received by the bottom plate of the paper feed cassette, which will be described later. The weight of the paper applied to the paper loading plate 45 becomes lighter than when the small size paper a is fed horizontally, and the force of pushing up the loading plate by the tension spring 50 becomes stronger, so that the feeding by the paper feed roller 43 is reduced. The paper force acts strongly on the top paper a.

On the other hand, when large size paper a is fed vertically, half of the paper weight is added to the paper loading plate 45, and when small size paper a is fed horizontally, the entire weight of the paper is added to the paper loading plate 45. 45, the paper weight applied to the paper loading plate 45 is almost the same in the mode in which the large size paper a is fed vertically and in the mode in which the small size paper a is fed horizontally, Compared to the case where the small size paper a is fed vertically, the weight of the paper applied to the paper loading plate 45 is doubled, and the force of pushing up the loading plate by the tension spring 50 is correspondingly weaker. As a result, the pressure with which the paper feed roller 43 presses the uppermost sheet a becomes smaller, and as a result, the paper feeding force of the paper feed roller 43 against the uppermost sheet a becomes weaker.

Therefore, if the spring pressure of the tension bar 250 is set so that an appropriate paper feeding force is obtained when small size paper a is fed lengthwise, then large size paper a is fed lengthwise or small size paper a is fed horizontally. Since paper feeding failure occurs during thread feeding, the spring pressure of the tension spring 50 is adjusted so that appropriate paper feeding force is obtained when large size paper a is fed vertically and small size paper a is fed horizontally. It is set.

However, when the spring pressure is set in this way, a strong paper feeding force acts on the topmost paper a when feeding small size paper a lengthwise, resulting in a situation where two sheets of paper a are fed. It was done.

That is, in the double feeding prevention means 44, the friction pad 5
The friction coefficient between the friction pad 4 and the paper a is set to be larger than the friction coefficient between the paper a and the friction pad 54 to prevent double feeding of the paper a when two sheets of the paper a are fed. However, immediately upstream of the double feed prevention section,
Since the uppermost paper a is strongly pressed against the paper feed roller 43 and is pushed and fed with a strong force, when two sheets of paper a are fed, the two sheets of paper a become one piece, and the above-mentioned Sometimes the paper passes between the paper feed roller 43 and the friction pad 54.

This two-sheet feeding of paper a is due to the replenishment of paper a to the paper feed cassette 41.
This was noticeable when the friction coefficient between the paper a and the paper a became larger than the friction coefficient between the two-sheet and three-sheet paper a.

SUMMARY OF THE INVENTION An object of the present invention is to provide a paper feeding device that appropriately prevents double feeding of paper through simple improvements.

[Means to solve the problem]

In order to achieve the above object, the present invention provides the paper feeding device described at the beginning, in which the mounting plate pushing up means is a mounting plate that is swingable around a support shaft parallel to the rotation axis of the paper feeding roller. It is composed of a push-up member and a tension spring that presses and urges the mounting plate push-up member toward the paper feed roller, and
An operating member for changing and setting the spring pressure of the tension spring is provided on the paper feed cassette loading section side in correspondence with the side plate of the paper feed cassette, while the pushing force of the loading plate by the tension spring is weak. A pressing member is provided on a side plate portion of the paper feed cassette that accommodates sheets of a size of It has characteristics.

[Effect]

According to the above-mentioned characteristic configuration, when the paper feed cassette containing sheets of paper of the size to which the tension spring acts is weak is loaded into the paper feed cassette loading section, as shown in FIG. , horizontal feed of small size paper a (
Alternatively, when the paper feed cassette 2, which accommodates large-sized paper vertically (longitudinal paper feeding), is loaded into the paper cassette loading section 4 as shown in FIG.
2 to release the tension spring 2 of the mounting plate pushing up means 14.
By increasing the spring pressure of 4, the uppermost paper a is strongly pressed against the paper feed roller 5, and the paper feeding force for the uppermost paper a becomes stronger.

Then, as shown in FIG. 6, the paper feed cassette 3, which has a paper storage configuration in which the small size paper a is fed vertically, is loaded into the paper feed cassette loading section 4 as shown in FIG. The spring pressure of the tension spring 24 is set so that an appropriate paper feeding force is applied to the uppermost paper a to prevent double feeding when the paper is loaded, and the paper storage configuration shown in FIG. Even when the paper feed cassette 3 that has been removed is loaded into the paper feed cassette loading section 4, appropriate paper feeding force is applied to the topmost paper a.
By setting the amount by which the operating member 22 is operated by the pressing member, the paper can be fed properly even if the weight of the paper applied to the paper loading plate 15 changes due to the difference in the paper feeding form, and the paper can be fed properly. double-sheet feeding is effectively prevented.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a paper feeder 1 in an image forming apparatus, and a second
This figure and FIG. 3 show a state in which a paper feed cassette 2.3 having a different configuration is loaded into the paper feed cassette loading section 4 of the paper feed device 1. As shown in FIG.

One of the paper feed cassettes 2 is A-
This is to accommodate paper for horizontal feeding of small size paper a such as 4 or B-5 (or lengthwise feeding of large size paper a such as A-3 or B-4), and A pressing member whose function will be described later is connected to the upper end of the front side of the side plate portions 2a on both sides, and as shown in FIG. This configuration does not include a pressing member, and the other dimensions and outline shape are exactly the same.

Returning to Figures 1 to 3, 5 in the figure is a paper feed roller;
Paper feed cassette 2 loaded in the paper feed cassette loading section 4
．． 3, the highest sheet a is fed.

Reference numeral 6 denotes a double-feed prevention means that constitutes a double-feed prevention mechanism 7 with the paper feed roller 5.
0, a g-bar pad 11 is attached to the upper end side of this crank-shaped arm 8, and the friction pad 11 is
A tension spring 12 that presses and urges the paper feed roller 5,
It is provided across the lower end side of the crank-shaped arm 8 and a holding member 13 which is connected to the bracket eye 0.

Reference numeral 14 denotes a mounting plate pushing means for pushing up the paper mounting plate 15 in the paper feeding cassette 2.3 toward the paper feeding roller 5, and as shown in FIG. An arm 18.18 is swingably attached to side plates (not shown) on both sides of the paper feed roller 5 via a support shaft 17 parallel to the rotating shaft 16 of the paper feed roller 5. In addition to providing a connecting member 19, a mounting plate pushing member 20 is provided in series at the longitudinal intermediate portion of the connecting member 19 toward the double feeding prevention means 6 side, and this mounting plate pushing member 20 is used for paper feeding. A biasing means 21 for pressing and biasing the roller 5 side is provided,
Place the top paper a in the paper feed cassette 2.3 on the paper loading plate 1.
The paper feed roller 5 is configured to be brought into pressure contact with the paper feed roller 5 via the paper feed roller 5 .

Reference numeral 25 designates the mounting plate pushing member 20 as the paper feed cassette 2.
The support shaft 2 is a fixed holding means for fixedly holding the supporting shaft 2 outside the insertion/extraction locus of FIG.
8 is pivotally attached to the lower end of one arm 18 so as to be rotatable over a predetermined angular range, while the mounting plate pushing up member 2
A locking member 29 is provided on the side plate (not shown) to lock the hook 26 in a state where the paper feed cassette 7) 2. A torsion coil spring 30 is provided for biasing.

Thus, the paper feed cassette 7) the paper feed cassette 7 for the loading section 4;
) 2.3, by operating the handle 27 to release the hook 26 from the locking member 29, a pushing force by the tension spring 24 is applied to the paper loading plate 15, and , the hook 26 is attached to the locking member 29
By locking the paper feed cassette throat 2.degree. 3 to and from the paper feed cassette loading section 4, it becomes possible to insert and remove the paper feed cassette throat 2.degree.

Next, the specific structure of the biasing means 21 provided in the mounting plate pushing up means 14 will be explained. An elliptical operating member 22 that comes into contact with the pressing member of the paper feed cassette 2 and rotates as the paper feed cassette 2 is loaded.
is pivotally connected to the side plate (not shown) via a shaft 23 parallel to the support shaft 17, and this operating member 22 and the arm 1
A tension spring 24 is provided across the
When the other paper feed cassette 3 shown in FIG. 6 is loaded in the paper feed cassette loading section 4, the operating member 22 is not rotated as shown in FIG. Only when the sheet is loaded into the paper feeder loading section 4, the operating member 22 is driven to rotate (see FIG. 2), and the spring pressure of the tension spring 24 is increased.

As shown in FIG. 3, when the other paper feed cassette 3 is loaded in the paper feed cassette loading section 4, the paper with the highest paper feed has an appropriate paper feed force that prevents double feeding. Even when the spring pressure of the tension spring 24 is set so that it is applied to By setting the amount of operation of the operating member 22 by the pressing member so that an appropriate paper feeding force is applied to the uppermost paper a, the amount of force applied to the paper loading plate 15 depending on the paper feeding form is set. Even if the paper weight changes, proper paper feeding is achieved while reliably preventing double feeding of paper a.

Note that a pressing member for pressing the operating member 22 to increase the pressure of the tension spring 24 may be provided only on the side plate portion 2a in the width direction of the one sheet feeder opening 2; Alternatively, the pressing member may be provided on the outer surface of the side plate portion 2a.

〔Effect of the invention〕

As described above, according to the paper feeding device of the image forming apparatus according to the present invention, a paper cassette containing paper of a size on which the pushing force of the loading plate by the tension spring is weak is loaded into the paper cassette loading section. In this case, the spring pressure of the tension spring is increased to increase the pressing force of the uppermost sheet of paper against the paper feed roller, and thus the paper feeding force of the paper feed roller, so that the paper storage Even if the weight of paper applied to the paper loading board changes due to differences in form,
This makes it possible to prevent the paper feeding force for the topmost paper on the paper loading plate from changing too much, and to maintain pressure so that an appropriate paper feeding force is obtained even if the weight of the paper changes. By setting the amount of operation of the operating member by the member,
Appropriate paper feeding that reliably prevents double sheet feeding has been achieved.

[Brief explanation of drawings]

Figure 1 is a side view of a paper feeder in an image forming apparatus;
Figures 3 and 3 are side views of the paper feed device showing paper feed cassettes of different configurations being loaded, Figure 4 is a perspective view of the means for pushing up the loading plate, and Figure 5 is a side view of the paper feeder for feeding small-sized paper horizontally. FIG. 6 is a perspective view of a paper feed cassette that accommodates small-sized paper in vertical feed mode, and FIG. 7 is a side view of a conventional paper feed device. be. 2.3... Paper feed cassette, 2a... Side plate section, 4...
・Paper feed cassette loading section, 5...Paper feed roller, 6...
Double feeding prevention means, 14... mounting plate pushing up means, 15.
...Paper mounting plate, 16... Rotating shaft, 17... Support shaft,
20... Riding board pushing member, 22... Operation member,
24...Tension spring, a...Paper, b...Press member. Applicant: Mita Kogyo Co., Ltd. Agent: Hideo Fujimoto, patent attorney

Claims (1)

[Claims] A paper feed roller that feeds and feeds the paper in the paper cassette is installed in the paper cassette loading section for removably loading the paper cassette, and this paper feed roller prevents double feeding of paper. A paper feeding device for an image forming apparatus, comprising means for pushing up a paper mounting plate in a paper feeding cassette loaded in the paper feeding cassette loading section toward a paper feeding roller, the paper feeding device comprising: The mounting plate pushing up means includes a mounting plate pushing up member that is swingable around a support shaft parallel to the rotation axis of the paper feed roller, and a tension force that presses and urges the mounting plate pushing up member toward the paper feeding roller side. An operating member consisting of a spring and for changing and setting the spring pressure of the tension spring is provided on the side of the paper feed cassette loading section in correspondence with the side plate of the paper feed cassette. A side plate portion of a paper feed cassette that stores paper of a size on which a weak pushing up force acts on the paper feed cassette is configured to press the operation member to increase the spring pressure of the tension spring as the paper feed cassette is loaded into the paper feed cassette loading section. A paper feeding device for an image forming apparatus, characterized in that a pressing member is provided.