JPH0640582A - Paper feeding mechanism - Google Patents

Abstract

PURPOSE:To provide a paper feeding mechanism capable of feeding selectively all different types of sheets without deforming so that the set height and occupied area of an overall image forming device are roughly the same as the outer dimensions of an image forming device in which a single-stage paper sheet feeding cassette is incorporated. CONSTITUTION:A paper sheet feeding cassette 9 is formed in double layer construction, and a sub cassette 17 is constructed so that it is placed over a main cassette 16 with larger external dimensions. The sub cassette 17 is fixed stably to the main cassette 16 at a fixing part 18, and is formed detachably. The main cassette 16 and the sub cassette 17 are formed so that their widths are the same and their lengths and heights are specified dimensions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feed mechanism in which small-sized trays are arranged in a large-sized tray so that papers of different sizes can be fed from both trays. This is an applicable paper feed mechanism.

[0002]

2. Description of the Related Art In image forming apparatuses such as electrophotographic copying machines, liquid crystal printers, and LED printers, different types of paper can be selected and fed without changing the trays in which the paper is stored. Some are configured to be. In such a conventional image forming apparatus, a tray is prepared for each of different types of sheets, and the trays are arranged in a superposed manner inside the machine or are extended outside the machine while being inclined at different levels.

However, in the image forming apparatus in which the trays are superposed in the machine, the height of the apparatus becomes higher than that of the tray exchange type machine outside the machine, and the tray is extended to the outside of the machine in a stepped manner. The device thus formed requires an occupied area in the width direction. As described above, both types are inconvenient in space.

[0004]

SUMMARY OF THE INVENTION In view of the above problems of the prior art, the present invention provides an image forming apparatus that can be made substantially the same as the external dimensions of the image forming apparatus without taking the installation height and occupied area of the entire image forming apparatus. With the goal.

[0005]

SUMMARY OF THE INVENTION According to the present invention, the above object is such that a sub-tray for accommodating and accommodating sheets of a first size can be detachably accommodated and a sheet of a second size larger than the first size can be stacked and accommodated. And a first paper feeding means for feeding the paper in the sub-tray, a second paper feeding means for feeding the paper in the main tray, the first, or The present invention is achieved by providing a sheet feeding mechanism including a driving unit that selectively operates one of the second sheet feeding units.

[0006]

EXAMPLES An example of the present invention will be described in detail below with reference to the drawings. FIG. 2 is a schematic configuration diagram showing an image forming apparatus to which the sheet feeding mechanism of this embodiment is applied. In FIG. 1, the image forming apparatus 1 is disposed in the housing 2 and has an image forming section including a photosensitive drum 3, a charger 4, a print head 5, a developing device 6, a transfer device 7, and a cleaner 8. A paper cassette 9 is mounted below the image forming unit, and a paper feeding unit that feeds the sheets stacked in the paper cassette 9 to the image forming unit is formed at the lower right of the image forming unit. There is. This paper feed unit is composed of paper feed rollers 10, 10 ′, a slip roll 11, and a standby plate 12. Also,
A fixing device 13 is provided on the left side of the image forming section, and a conveyance roll 14 is provided on the paper output side of the fixing device 13.
Is provided. The sheet fed from the sheet cassette 9 by the sheet feeding roller 10 as the second sheet feeding means or the sheet feeding roller 10 ′ as the first sheet feeding means is formed on the photosensitive drum 3. The toner image obtained by developing the electrostatic latent image by the developing device 6 is transferred, and the fixing device 13 thermally fixes the toner image on the sheet. The sheet on which the image is formed is sent upward from the fixing device 13 by the transport roll 14 and is discharged to the paper discharge unit 15 by the paper discharge roll 14 ′.

Next, the detailed structure of the above-mentioned paper feed cassette 9 will be described with reference to FIG. The sheet feeding cassette 9 is formed in a two-layer structure, and a sub cassette 17 as a sub tray is provided so as to be placed above the main cassette 16 as a main tray having a large outer dimension. This sub-cassette 17 includes a main cassette 16 and a fixed portion 1.
It is stably fixed at 8, and is detachable. The main cassette 16 and the sub-cassette 17 have the same width, and the length and the height are each made to have a predetermined size.

The main cassette 16 has a structure substantially similar to that of a general paper feed cassette. When the main cassette 16 is pushed into the main body device 1 (not shown) in the direction of arrow A and mounted, the bottom plate 19 is attached to the main body. This is a configuration in which the sheets stacked by being pushed up by a push-up plate (not shown) formed in the apparatus 1 are set at predetermined positions. Positioning ribs 20, 20 are integrally formed with the casing of the cassette at a predetermined position below the side surface of the main cassette 16, and serve as a guide when the main cassette 16 is attached to the main body device 1 and inside the device. Also has the role of determining the position of. When the main cassette 16 is attached to a predetermined position of the main body device by the guide of the ribs 20, 20, the push-up plate pushes up the bottom plate 19 of the main cassette 16, and the stacked sheets are placed at the position where they are abutted on the paper feed roller 10. Hold.

Next, the sub cassette 17 is constructed so as to be placed on the main cassette 16. This becomes one-sided by notching the side surface of the main cassette 16 into a predetermined shape and fitting it with the side surface of the sub-cassette 17 formed in a shape that engages with this notch surface. The side surface of the sub-cassette 17 and the side surface of the main cassette 16 are formed so as to be one and the same surface, and a part of these side surfaces is used for detecting the size of the sheets stacked in each cassette. The member 21 is formed. When the sheets are stacked in the respective cassettes, for example, when the sheet A 3 (A3) is loaded on the main cassette 16, the sheet A 4 (A4) is loaded on the sub-cassette 17. .

The tip portion of the above-mentioned sub-cassette 17 which is inserted in the main body device in the traveling direction is located rearward from the tip portion of the main cassette 16 in the same direction, and a push-up rod is provided on the side surface near the tip of the sub-cassette 17. 22 is formed. The push-up bar 22 is connected to a push-up plate formed in the sub-cassette 17 via a spring described later, and the push-up plate is configured to move a bottom plate 23 of the sub-cassette 17 up and down in an interlocking manner. . Then, the push-up rod 22 contacts the sliding surface 24a of the push-up member 24 formed on the main body device (not shown) as shown in FIG. 3 when the sub-cassette 17 is attached to the main body device (direction of arrow A). They come into contact (in the direction of arrow B) and are pushed up so as to slide along the direction of arrow C. For this reason, a cut groove 25 is provided on the side surface of the sub-cassette 17 for the push-up rod 22 to move upward (in the direction of arrow D).

The operation of the paper feed mechanism configured as described above will be described below. First, the main cassette 16 and
The paper feed cassette 9 composed of the sub-cassette 17 placed at a predetermined position above the main cassette 16 is mounted in the main body. When pushing the paper feed cassette 9 into the main body device, the push-up rod 22 is pushed up along the sliding surface 24a of the push-up member 24 in the main body device, and the push-up plate 22 is connected to the push-up rod 22 via a spring. Move up. The bottom plate 23 of the sub-cassette 17 is arranged at a predetermined position by the movement of the push-up plate, and the main body device is stabilized by the ribs 20 formed on the side surface of the main cassette 16 as described above. Then, the paper size detecting device 21 formed in the paper feed cassette 9 determines the size of each paper loaded in each cassette of the paper feed cassette 9.

The bottom plate 19 of the main cassette 16 is
As shown in FIG. 4, it is pushed up by a push-up plate 27 formed on the main body via a spring 26. on the other hand,
When sheets are loaded in the sub-cassette 17, the bottom plate 23 is pushed upward by the push-up rod 22 via the spring 28 and the push-up plate 29 as shown in FIG.

Further, FIGS. 6 and 7 show a state in which the sheets P are actually stacked in the sheet feeding cassette 9. When the sheets P are stacked on the main cassette 16 and the sub-cassette 17, large-sized sheets can be stacked on the main cassette 16 as described above, and the sheets P smaller than the main cassette 16 are stored in the sub-cassette 17. Can be loaded. When the sheets are stacked on both of these cassettes, the sheets stacked on the main cassette 16 can be stacked in a thickness obtained by subtracting the height of the casing of the sub-cassette 17. For example, when the sub-cassette 17 is not placed (FIG. 7), it is possible to add and stack sheets in the space where the sub-cassette 17 was stored in the main cassette 16.

In this way, the paper feed cassette 9 is mounted in the main body apparatus, and either the paper in the sub cassette 17 or the paper in the main cassette 16 is selected according to the paper size designation from a control circuit (not shown). Each paper feed roller 10,
10 'selectively conveys in sequence in the conveying path direction.

[0015]

As described in detail above, according to the present invention, the installation height and the occupied area of the image forming apparatus are almost the same as the external dimensions of the image forming apparatus with the built-in single-stage sheet feeding cassette. It is possible to selectively feed sheets of different sizes without making them bulky.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a sheet feeding mechanism of the present invention.

FIG. 2 is a schematic configuration diagram showing an image forming apparatus to which a sheet feeding mechanism of the invention is applied.

FIG. 3 is a schematic perspective view showing the vicinity of a push-up bar of the paper feeding mechanism of the present invention.

FIG. 4 is a diagram showing a schematic side cross section of a sheet feeding mechanism of the present invention.

FIG. 5 is a diagram showing a schematic side cross section of a paper feeding mechanism of the present invention.

FIG. 6 is a diagram showing a schematic side cross section of a paper feeding mechanism of the present invention.

FIG. 7 is a diagram showing a schematic side cross section of the paper feeding mechanism of the present invention.

[Explanation of symbols]

 9 Paper feed cassette 16 Main cassette 17 Sub-cassette 18 Fixing part 19 Bottom plate 20 Rib 21 Paper detection device 22 Push-up bar 23 Bottom plate

Claims (1)

[Claims] 1. A paper cassette comprising a main tray for detachably accommodating a sub-tray for accumulating and accommodating sheets of a first size, and for accommodating and accommodating sheets of a second size larger than the first size. Any of a first paper feeding means for feeding the paper in the sub-tray, a second paper feeding means for feeding the paper in the main tray, the first or the second paper feeding means A sheet feeding mechanism comprising: a driving unit that selectively operates one of the two.