JPH08119489A - Paper feeding device - Google Patents

Abstract

PURPOSE: To prevent error detection even when paper sheets are small in number, thin, and light in weight in detection of the paper end by means of a paper end sensor projecting upward from a paper feeding base. CONSTITUTION: By means of a slide mechanism 26 arranged in a side fence 22, a paper holding member 25 is supported freely slidably in the vertical direction from the uppermost position to the lowermost position of a paper feeding base 3. A paper sheet 2 is pressed onto a paper end sensor 5 by means of the paper holding member 25.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device used in a copying machine or a printing machine.

[0002]

2. Description of the Related Art Conventionally, a paper feeding device has been used as a device for automatically feeding a printing paper to a copying machine or a printing machine, and there are various forms of such a paper feeding device.

For example, as shown in FIG. 7, a sheet feeding device 1 disclosed in Japanese Patent Laid-Open No. 204204/1990 has a sheet feeding table 3 on which a large number of printing sheets 2 are stacked. . The paper feed table 3 is supported by an up-and-down drive mechanism (not shown) so as to be vertically movable, and a paper feed roller 4 is arranged above the paper feed table 3 so as to be vertically movable. There is.

A paper end sensor 5 is mounted on the bottom surface of the paper feed tray 3 at a position facing the paper feed roller 4.
More specifically, the photo interrupter 6 of the paper end sensor 5 is arranged below the paper feed table 3, and the rotatable filler 7 of the paper end sensor 5 projects upward from the opening 8 of the paper feed table 3. There is. Elevating control means (not shown) is provided to prevent the paper feed table 3 from being raised by the elevation drive mechanism when the paper end sensor 5 does not detect the printing paper 2.

In such a structure, when the printing paper 2 placed on the paper feed tray 3 is fed, the paper feed roller 4 descends and abuts the printing paper 2, and in this state, the paper feed roller 2 moves. The printing paper 2 is fed by being rotated. When the printing paper 2 on the paper feed tray 3 is reduced by such feeding, the paper feed tray 3 is raised and the uppermost position of the printing paper 2 is maintained at an appropriate position. When the paper end sensor 5 detects the end of the printing paper 2, the paper feed table 3 is not raised, so that the mechanism for raising and lowering the paper feed tray 3 is properly stopped to prevent damage.

In addition, in the paper feeding device 1 as described above, in general, in order to prevent the skew and the edge of the printing paper, the paper feeding table 3 is provided.
A pair of side fences (not shown) that hold the printing paper 2 placed on the paper from both sides and a pair of paper holding members (not shown) that hold both ends of the printing paper 2 from above are provided. There is. Some of these sheet holding members are fixed to the upper edge of the tip of the side fence, and some are attached to the tip of the side fence so as to be vertically rotatable. The rotatable paper holding member is arranged such that the upper edge of the side fence is the lowest, the position rotated upward is the highest, and when the printing paper 2 is replenished to the paper feed table 3, it is arranged at the highest.
When holding the fed printing paper 2, it is arranged at the lowest position.

[0007]

In the paper feeding device 1 disclosed in Japanese Patent Laid-Open No. 204204/1990, the printing paper 2 is detected by the paper end sensor 5 projecting from the bottom surface of the paper feeding table 3, so that this printing is performed. When the number of sheets 2 is small and thin and light, as shown in FIG. 8, the paper end sensor 5 may lift the printing sheet 2 and falsely detect the end of the sheet. Such erroneous detection also occurs when the printing paper 2 is curved due to moisture absorption or reuse.

As means for solving such a problem,
It is conceivable that the paper feed table 3 is raised and stopped at an appropriate position, the paper feed roller 4 is lowered and the printing paper 2 is pressed from above, and the detection of the paper end sensor 5 is executed in this state. However, the paper end sensor 5 cannot detect the printing paper 2 unless the paper feed table 3 is raised and stopped at an appropriate position to detect the end of paper and the paper feed roller 4 is lowered in this state. Detection of termination is delayed.

If a paper holding member for holding both sides of the leading edge of the printing paper 2 from above is provided as described above, the printing paper 2 can be paper-printed without pressing the paper feed roller 4 as described above. It seems that it can be detected by the end sensor 5. However, since the paper holding member is located at the upper edge of the side fence as described above, the paper end sensor 5 must be moved up to the position where the print paper 2 comes into contact with the paper holding member. Cannot be detected.

In particular, in the case of a large-capacity sheet feeding device 1 in which a large amount of printing paper 2 is placed on the sheet feeding table 3, since the sheet feeding table 3 moves largely in the vertical direction, the sheet feeding table 3 moves downward. When positioned, the uppermost surface of the small number of printing papers 2 is largely separated from the paper feed roller 4 and the paper holding member. For this reason, since the paper end sensor 5 starts detecting after the paper feed table 3 is moved upward, it takes time to detect the paper.

[0011]

According to the first aspect of the present invention,
A sheet feeding table on which sheets are stacked is provided, and an elevating and lowering driving mechanism for movably supporting and positioning the sheet feeding table is provided, and the sheet is detected by protruding from the lower end of the sheet feeding table. A paper end sensor is provided, and a pair of side fences that hold the paper placed on the upper surface of the paper feed table from both sides are provided, and both ends of the leading edge of the paper placed on the upper surface of the paper feed table are held from above. A pair of sheet holding members are provided, and the side fence is provided with a slide mechanism that supports the sheet holding members in the up-down direction from the uppermost position to the lowermost position of the paper feed table.

According to a second aspect of the invention, in the first aspect of the invention, a member holding mechanism for holding the sheet holding member above is provided.

According to a third aspect of the present invention, in the second aspect of the present invention, a sheet cover is provided at a position facing the sheet feed table from above so that the sheet cover can be opened and closed. A holding release mechanism is provided to release the holding.

[0014]

According to the first aspect of the present invention, since the sheet holding member slides vertically from the uppermost position to the lowermost position of the paper feed tray by the slide mechanism provided on the side fence, the paper feed tray is positioned below. Even if the number of sheets is small, the sheet holding member descends and holds both sides of the leading edge of the sheet from above.

According to the second aspect of the present invention, the member holding mechanism holds the paper holding member at the upper side, so that the paper holding member does not get in the way when the paper is supplied to the paper feed tray.

According to the third aspect of the present invention, when the paper cover is closed, the holding of the paper holding member by the member holding mechanism is released by the holding release mechanism, so that the paper is held when the paper supply is completed and the paper cover is closed. The member automatically descends and holds both sides of the leading edge of the paper from above.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. Regarding the large-capacity sheet feeding unit 9 which is the sheet feeding device of the present embodiment, the same parts as those of the above-described sheet feeding device 1 are denoted by the same names and reference numerals and detailed description thereof will be omitted. In addition, in this embodiment, the front and rear, and right and left are shown with the sheet feeding direction of the sheet feeding unit 9 as the front,
3 is the front of the paper feeding unit 9, and the upper part of FIG. 3 is the right of the paper feeding unit 9. However, these front, rear, left, and right directions are shown for convenience in order to simplify the description, and do not limit the actual installation and use directions of the apparatus.

First, the paper feeding unit 9 of this embodiment is shown in FIG.
As shown in FIG. 3, it is formed as a part of the image forming apparatus 10. The image forming apparatus 10 includes an apparatus main body 11
The image forming unit 12 is arranged in the upper part of the table, and the two sheet feeding cassettes 13 and 14 are arranged in the lower part. A paper transport path 15 that communicates from these paper feed cassettes 13 and 14 to the image forming unit 12 is formed so as to pass through the rear portion of the apparatus main body 11.

A paper feed port 16 communicating with the paper feed path 15 is formed on the rear surface of the apparatus main body 11, and a paper feed unit 9 and a manual tray 17 are provided so as to communicate with the paper feed port 16. It is connected to the device body 11. Inside the main body 11 of the apparatus, a paper feed roller 4 is arranged in the paper feed port 16 so as to be movable in the vertical direction, and at a position where the paper feed roller 4 communicates with the paper feed path 15, a feed roller is provided. A sheet separating mechanism 20 including 18 and a separating roller 19 is arranged.

Since the paper feeding unit 9 of this embodiment is formed as a large-capacity type capable of accommodating 1000 sheets of printing paper 2, the vertical movement of the paper feeding table 3 by an elevating drive mechanism (not shown). The amount is also set large. This paper feed stand 3
A paper end sensor 5 is attached to the paper feed sensor 4, and the paper end sensor 5 faces the paper feed roller 4 of the apparatus body 11 from below.

As shown in FIG. 3, a pair of side fences 2 are provided on both sides inside the unit main body 21 of the sheet feeding unit 9.
2 are arranged, and near the tips of these side fences 22, rail-shaped guide portions 2 communicating in the up-down direction.
3 are formed. As shown in FIGS. 3 and 4, sliders 24 are slidably mounted on these guide portions 23, and a paper holding member 25 is provided so as to project from the lower part of these sliders 24 to the inside. Therefore, the slide mechanism 2 including the guide portion 23 and the slider 24 is provided.
6, the pair of paper holding members 25 are slidably supported in the vertical direction from the uppermost position to the lowermost position of the paper feeding table 3 at positions facing both ends of the paper feeding table 3 from above.

Incidentally, the unit main body 21 is the device main body 27.
And a paper cover 28. The paper cover 28 is openably and closably mounted on the apparatus main body 27 and faces the paper feed tray 3 from above. A cover sensor (not shown) for determining the open / closed state of the paper cover 28 is provided, and the timing of paper detection by the paper end sensor 5 is set when the paper cover 28 is closed.

In such a structure, first, when the printing paper 2 is fed from the paper feeding unit 9 to the image forming section 12, as shown in FIG.
Keep it closed on the rear side. In this state, the device body 11
When a switch (not shown) is operated, the paper feed roller 4 descends to come into contact with the uppermost printing paper 2, and rotates in this state to feed the printing paper 2 to the paper feed port 16. The printing paper 2 is separated into one sheet by the paper separating mechanism 20 and the paper conveying path 1
The sheet of printing paper 2 is fed to the image forming section 12 as it is fed to the image forming section 12.

The printing paper 2 is fed by the above-mentioned feeding.
Is decreased, the paper feed tray 3 is raised until an upper limit detection sensor (not shown) detects the print paper 2 to properly connect the uppermost print paper 2 to the paper feed port 16 of the apparatus main body 11. Place in position. At this time, when the paper end sensor 5 detects the end of the printing paper 2, the elevation of the paper feed tray 3 is stopped to prevent the lifting drive mechanism from being damaged.

At this time, since the paper end sensor 5 protruding from the bottom surface of the paper feed tray 3 detects the end of the paper, when the print paper 2 is small in number and thin and light, the paper end sensor 5 lifts the print paper 2 to end the paper. There is a concern of false detection. However, in the paper feeding unit 9 of the present embodiment, the paper holding member 25 slides in the vertical direction from the uppermost position to the lowermost position of the paper feeding base 3, so that the printing paper 2 placed on the paper feeding base 3 holds the paper. Both ends of the leading edge are held from above by the member 25, and the paper end sensor 5 causes the printing paper 2
There is no false detection of paper end due to lifting.

In particular, the paper feeding unit 9 of this embodiment is 1000
Since it is a large-capacity type that can store as many sheets of printing paper 2, the vertical movement of the paper feed table 3 is large, but the paper holding member 2
Since 5 slides from the uppermost position to the lowermost position of the paper feed tray 3, the end of paper can be accurately and quickly detected regardless of the position of the paper feed tray 3.

When the printing paper 2 is replenished to the paper feeding unit 9 of this embodiment, the paper cover 28 is attached to the apparatus main body 27.
To expose the paper feed tray 3 and the side fence 22, and manually slide and hold the paper holding member 25. In this state, supply the printing paper 2 onto the paper feed table 3,
When the paper holding member 25 is released after this completion, the paper holding member 25 falls by its own weight and holds both sides of the leading edge of the printing paper 2 from above, so the presence or absence of the printing paper 2 is reliably detected by the paper end sensor 5. It will be in the state to be.

Since the paper detection start timing of the paper end sensor 5 is set when the paper cover 28 is closed, the print paper 2 is held by the paper holding member 25 when the paper supply is completed as described above. Then, immediately after this, the paper detection by the paper end sensor 5 is started.

In the present embodiment, the paper feeding unit of the image forming apparatus 10 is exemplified as the paper feeding device, but the present invention is not limited to the above embodiment, and for example, the original paper is fed to the image reading device. The present invention is also applicable to a paper feeding device for feeding and a paper feeding device for feeding paper to a paper cutting device.

Next, a second embodiment of the present invention will be described below with reference to FIGS. Regarding the paper feeding unit 29 which is the paper feeding device of the present embodiment, the same parts as those of the paper feeding unit 9 described as the first embodiment are denoted by the same names and reference numerals and detailed description thereof will be omitted. .

In the sheet feeding unit 29 of this embodiment, a pair of permanent magnets 31 as a member holding mechanism are mounted on both sides of the stay 30 arranged above the tip of the side fence 22. The sheet holding members 25 are individually opposed from above. Further, projections 32, which are holding release mechanisms, are provided on both sides of the leading end of the upper surface of the paper cover 28, and these projections 32 face the paper holding member 25 from above inside the permanent magnet 31. When the paper cover 28 is closed, the paper cover 28 projects downward from the permanent magnet 31.

In such a structure, when the printing paper 2 is replenished to the paper feeding unit 29 of this embodiment, the paper cover 28 is opened from the apparatus main body 27 to expose the paper feeding table 3 and the side fence 22. The sheet holding member 25 is manually slid upward and attracted to the permanent magnet 31. That is,
Since the sheet holding member 25 is held upward by the permanent magnet 31, it is not necessary to manually hold the sheet holding member 25 upward. For this reason, the printing paper 2 can be easily replenished on the paper feed tray 3, and the work burden on the user can be reduced.

When the paper cover 28 is closed to the apparatus main body 27 after the completion of the paper replenishment, the convex portion 32 of the paper cover 28 comes into contact with the paper holding member 25 from above, so that the paper holding member 25 is permanently attached. It separates from the magnet 31 and falls by its own weight. Therefore, it is not necessary to manually separate the paper holding member 25 from the permanent magnet 31, and the paper holding member 25 automatically holds the printing paper 2 when the paper cover 28 is closed. Is reduced, and there is no problem even if the user forgets to drop the paper holding member 25.

In the paper feeding unit 29 of this embodiment,
Since the member holding mechanism for holding the paper holding member 25 above is provided by the permanent magnet 31 and the holding release mechanism for releasing the holding of the paper holding member 25 when the paper cover 28 is closed is provided by the convex portion 32, a simple structure is provided. With no driving force required,
The paper holding member 25 is held and released.

However, the present invention is not limited to the above embodiment, and the member holding mechanism as described above may be provided by a suction cup, an adhesive, an electromagnet, a lock mechanism (all not shown) and the like. Is. For example, when the member holding mechanism is an electromagnet, the holding release mechanism can be realized as a mechanism for releasing the electric power of the electromagnet, and when the member holding mechanism is a lock mechanism, the holding release mechanism can be realized as a mechanism for opening the lock mechanism. .

[0036]

According to the first aspect of the present invention, a paper sheet holding member is provided with a slide mechanism for vertically slidably supporting the paper sheet holding member from the top to the bottom of the paper feed tray. Even when the number of sheets is small and thin, the sheet is pressed against the paper end sensor by the sheet holding member, so that the paper end sensor can be prevented from erroneously detecting the end of the sheet.

According to the second aspect of the invention, since the member holding mechanism for holding the sheet holding member above is provided, it is necessary to manually hold the sheet holding member upward when replenishing the paper to the paper feed tray. Since it does not exist, the work load on the user can be reduced.

According to the third aspect of the present invention, a paper cover is provided at the position facing the paper feed table from above so as to be openable and closable, and when the paper cover is closed, the holding mechanism releases the holding of the paper holding member by the member holding mechanism. Since the paper holding member automatically lowers the position to hold the printing paper when the paper cover is closed to the main body after the paper supply is completed, the holding of the paper holding member by the member holding mechanism is manually released. There is no need to do so, the work load on the user is reduced, and there is no problem even if the user forgets to lower the paper holding member.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing a sheet feeding device according to a first embodiment of the present invention.

FIG. 2 is a vertical cross-sectional side view showing an image forming apparatus including a sheet feeding device as a part.

FIG. 3 is a plan view showing the inside of the paper feeding device.

FIG. 4 is an exploded perspective view showing a side fence, a sheet holding member, and a slide mechanism.

FIG. 5 is a vertical sectional side view showing a paper feeding device according to a second embodiment of the present invention.

FIG. 6 is a vertical sectional front view showing a paper feeding device.

FIG. 7 is a vertical cross-sectional side view showing a sheet feeding device of a conventional example.

FIG. 8 is a vertical cross-sectional side view showing a state in which the printing paper is released upward.

[Explanation of symbols]

 2 Printing Paper 3 Paper Feeding Table 5 Paper End Sensor 9,29 Paper Feeding Device 22 Side Fence 25 Paper Holding Member 26 Slide Mechanism 28 Paper Cover 31 Member Holding Mechanism 32 Holding Release Mechanism

Claims (3)

[Claims] 1. A paper feed table on which sheets are stacked, an up-and-down drive mechanism for movably supporting and positioning the paper feed table in the up-and-down direction, and a sheet projecting from a lower end to a front end portion of the paper feed table. A paper end sensor for detecting the above, a pair of side fences for holding the paper placed on the upper surface of the paper feed tray from both sides, and both sides of the leading edge of the paper placed on the upper surface of the paper feed tray from above. It has a pair of paper holding members for holding, and a slide mechanism which is provided on the side fence and slidably supports the paper holding member in the vertical direction from the top to the bottom of the paper feed table. Paper feeder. 2. The sheet feeding device according to claim 1, further comprising a member holding mechanism for holding the sheet holding member above. 3. A paper cover is provided at a position facing the paper feed table from above so as to be openable and closable, and a holding release mechanism is provided for releasing the holding of the paper holding member by the member holding mechanism when the paper cover is closed. The paper feeding device according to claim 2.