JPH0266028A - Sheet feeder - Google Patents

Abstract

PURPOSE:To easily set up or off a paper casset by forming from resilient material a contact part which is connected to the upper surface of paper to detect paper empty. CONSTITUTION:A paper empty detecting mechanism 6 consists of a tightly coiled spring 7, the support plate 8 thereof and a sensor 9 and the coiled spring 7 is held turnably about a pin 8c which holds the support plate 8. When a sheet casset 3 on which sheets P are held is inserted, the coiled spring 7 of which the front end is in contact with the upper surface of the sheets on a push-up board 4 is turned upward so that a sensor 9 generates the detection signal. And if paper P is out, the front end of the coiled spring 7 falls in the notch 4b of the press-up board 4 so that the sensor 9 generates the paper empty signal. When the casset 3 having no paper thereon is extracted, the front end of the spring 7 is flexed and goes over the notch 4b due to the elasticity so that the casset 3 may be extracted smoothly.

Description

[Detailed description of the invention] How many moons are on the skin! The present invention relates to a paper feeding device, and particularly to a paper feeding device that feeds sheets one by one from a paper feeding cassette that can be detachably attached to a paper feeding port of an image forming apparatus main body such as a copying machine.

2. Description of the Related Art In general, a paper feed device of a copying machine is equipped with a paper empty detection mechanism for detecting whether or not paper is stacked and accommodated in a paper feed cassette. Various paper empty detection mechanisms of this type have been proposed in the past, and are broadly classified into light detection methods and lever detection methods. In the former, a transmission type photo sensor consisting of a light emitting element and a light receiving element is placed above and below the paper feed port, and its optical axis passes through a notch formed in the push-up plate of the paper feed cassette. It is something. That is, when paper is stacked on the push-up plate, the paper blocks the optical axis of the photosensor, and when the paper runs out, the optical axis is opened. Paper empty is detected using this on/off signal. The latter has a rotatable lever above the paper feed slot, and the tip of the lever can fall into a notch formed in the push-up plate of the paper feed cassette, allowing the lever to rotate when the paper runs out. Paper empty is detected by detecting it with a photo sensor.

Problems to be Solved by the Invention However, conventional photodetection methods have the problem of being expensive because they use a photosensor that requires two elements: a light emitting element and a light receiving element.

Furthermore, since the lever detection method uses a photointerrupter as a sensor, it is inexpensive in that respect. However, since the lever is made of a rigid body, there is a risk of it digging into the paper and damaging it, and in order to prevent the lever from getting caught on the cassette box body etc. when pulling out the paper feed cassette, it is necessary to attach a retraction mechanism for the lever. After all, it cannot be produced cheaply,
It also has the problem of poor space efficiency.

SUMMARY OF THE INVENTION An object of the present invention is to provide a paper feeding device equipped with a paper empty detection mechanism that is space efficient, allows the conventional structure to be used as is, and can be manufactured at low cost.

In order to solve the above problems, the paper feed device according to the present invention provides the following features: (a) When paper is placed on the push-up plate of the paper feed cassette, the upper surface of the paper is (b) an elastic body whose leading end contacts and whose leading end drops into a notch formed in the push-up plate when no paper is placed; (b) an elastic body for detecting the operating position of the elastic body; It is characterized by being equipped with a sensor and.

(g) - In the above configuration, when the paper feed cassette containing paper is inserted into the paper feed port of the image forming apparatus main body, the tip of the elastic body contacts the top surface of the paper, and this contact position The sensor detects the paper and generates a signal indicating that paper is present in the paper feed cassette.

On the other hand, when all the paper has been fed, the tip of the elastic body falls into the notch of the push-up plate, and this fall position is similarly detected by the sensor, and a signal indicating paper empty is generated. These signals are displayed, for example, on the operation panel of the image forming apparatus main body.

By the way, since the member that functions as the detection body is made of an elastic body, it will not dig into the paper and damage it.
Even if the paper feed cassette comes into contact with the wall of the cassette box body when it is attached or removed, it bends due to its own elasticity and overcomes it, so there is no need for a special evacuation mechanism. Furthermore, it is possible to use an inexpensive photointerrupter as the sensor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a paper feeding device according to the present invention will be described with reference to the accompanying drawings.

This paper feeding device (1) consists of a paper feeding cassette 3 that can be attached to and removed from the paper feeding port (2) of the main body of the copying machine, and a paper feeding cassette (3) for pushing up the paper (P) stored in the paper feeding cassette (3). a push-up mechanism (5), a paper empty detection mechanism (6),
It is comprised of a feeding means (20) that is disposed inside the paper feeding port (2) and feeds sheets one by one.

The paper feed cassette (3) has paper (P) at the bottom of the box (3a).
) is provided with a push-up plate (4) for loading and accommodating.

This push-up plate (4) is rotatably attached to a rear end (not shown) as a fulcrum, and has a notch (4b) formed at its tip. This notch (4b) is used in common with the notch for recessing the lever in the conventional lever detection method, or the notch for passing the optical axis in the optical detection method.

The push-up mechanism (5> can be placed at the bottom of the paper feed opening 2),
A pressing plate (5b) having a curved tip is fixed to a shaft (5a) that can be driven by a driving means (not shown). By driving the press plate (5b) clockwise,
Enter the box body (3a) from the bottom and push up the push-up plate (4).
cam plate (4a), and rotates the push-up plate (4) upward.

The paper empty detection mechanism (6) is composed of a tightly wound coil spring (7), its support plate (8>), and a sensor (9>) consisting of a photointerrupter.
It is arranged above the paper feed port (2).

The coil spring (7) is attached to the protrusion (8b) of the support plate (8).
It is fixed by fitting the rear end to the support plate (
It is rotatable about the bottle (8c) holding the bottle (8) as a fulcrum. The reason why the fill spring (7) is tightly wound is to prevent the fill spring (7) from getting caught when it comes into contact with various parts of the box body (3a) when the paper feed cassette (3) is attached or detached, as explained below. This is to prevent the paper (P) stored in the paper feed cassette (3) from being caught between the coil springs (7). Further, the tip of the fill spring (7) is bent inward so as not to damage the paper (P). The sensor (9) is attached to the support plate (
8), it can be fixed to the plate (10), and the head (8) of the support plate (8) is inserted into the slit (not shown) where the optical axis is located.
8a) can move forward and backward. When the head (8a) enters the slit, the optical axis is blocked, and when the head (8a) retreats, the optical axis is completely opened. In addition, since the sensor (9) is attached with the slit through which the head (8a) moves forward and backward facing toward the back, erroneous detection due to the influence of external light is less likely to occur.

The feeding mechanism (20) includes a first paper feeding roller (21) and a second paper feeding roller (21).
This is a well-known device consisting of a paper feed roller (22) and a separation roller (23). Each roller (21), <22
), (23) are both rotated counterclockwise by the driving force from the main motor inside the copying machine, and the first paper feed roller (2
The top layer of paper (P) that has been completely fed out in step 1) is prevented from misfeeding such as double feeding by the second paper feed roller (22) and separation roller (23), and is transferred one by one to the transfer section in the main body. transported to.

In the above configuration, when the paper feed cassette (3) containing paper (P) is inserted into the paper feed port (2), the tip of the coil spring (7) is connected to the push-up plate (4). The head (8a) of the support plate (8) blocks the optical axis of the sensor (9) by contacting the upper paper (P) and rotating upward, so that the sensor (9) receives the paper detection signal. Output (first
(See figure), as the paper (P) decreases, the push-up mechanism (5) is driven and the push-up plate (4) moves upward, keeping the top surface of the paper (P) at the same height. do. Therefore, the paper detection signal continues to be output as long as even one sheet of paper (P) remains.

On the other hand, when the paper (P) runs out, the coil spring (7
) falls into the notch (4b) of the push-up plate (4) and rotates clockwise, the head (8a) of the support plate (8) retreats from the optical axis of the sensor (9), The sensor (9) outputs a paper empty detection signal (see FIG. 2). These detection signals are displayed on the operation panel of the copying machine.

Next, the operation of the coil spring (7) when attaching and detaching the paper feed cassette (3) will be explained.

Paper feed cassette (3) containing paper (P) in the paper feed slot (2)
), the coil spring (7) is pushed by the front wall (3b) of the cassette box body (3a), rotates upward, climbs over the front wall (3b), and comes into contact with the paper (P). (
(See Figure 3).

When the empty paper feed cassette (3) is pulled out, the fill spring (7) falls into the notch (4b).
The tip engages with the edge of the notch (4b) and gets over the notch (4b) while being deflected by its own elasticity (see Fig. 5).

Also, with the paper (P) stored in the paper feed cassette (3
) is pulled out, the top surface of the paper (P) and the box body (3a
The tip of the fill spring (7) gets caught in a part of the corner formed by the front wall (3b) of becomes.

Note that the paper feeding device according to the present invention is not limited to the above embodiments, and can be variously modified within the scope of the gist.

In particular, the elastic body that comes into contact with the top surface of the paper is not limited to the fill spring (7), but may be made of a rubber material, for example, and even when a fill spring is used, it does not necessarily have to be tightly wound.

Further, although a photointerrupter is used as a sensor, other non-contact type sensors or contact type switches may be used in place of this sensor.

As is clear from the above explanation, according to the present invention, an elastic body is used as a contact member for contacting the top surface of the paper that has not been accommodated in the paper feed cassette to detect paper empty. Therefore, there is no risk of the contact member biting into the paper and damaging it, and when the paper feed cassette is attached or removed, it flexibly abuts each part of the cassette box body and retreats, so there is no need to provide an evacuation mechanism. Moreover, inexpensive photo-interchangers and labdas can be used as sensors, and the push-up plate having a notch can be used in common with conventional ones, making it possible to manufacture the sensor at low cost.

[Brief explanation of the drawing]

The drawings show an embodiment of the paper feeding device according to the present invention, and FIG. 1 is a cross-sectional view of the paper feeding cassette loaded with paper installed in the paper feeding port, and FIG. 2 is a paper feeding device with the paper empty. A cross-sectional view of the state, Figure 3 is a cross-sectional view when the paper feed cassette is inserted,
FIGS. 4 and 5 are cross-sectional views when the paper feed cassette is pulled out. (1)...Paper feed device, (2)...Paper feed slot, (3)...
・Paper feeding power cent, <4) ・Push-up plate, (4b)・
...Notch, (6)...Paper empty detection mechanism, (7>...Fill spring (elastic body), (8)...
...Support plate, (9)...Sensor.

Claims (1)

[Claims] 1. In a paper feeding device that feeds sheets one by one from a paper feeding cassette that is detachably attached to a paper feeding port of an image forming apparatus main body, the paper is placed on a push-up plate of the paper feeding cassette. an elastic body whose leading end contacts the top surface of the paper when the paper is placed, and whose leading end falls into a notch formed in the push-up plate when the paper is not placed; A paper feeding device comprising: a sensor for detecting the operating position of the sheet;