JPS61238633A - Paper detector - Google Patents

Abstract

PURPOSE:To make paper detection sure enough and smooth motion performable even when a paper cassette passes through, by supporting the top of an arrow type lever slidably so as to make it contact with paper inside the cassette, while detecting a sliding position of the lever. CONSTITUTION:When a paper cassette 19 is set up, compressive force to a coil spring 24 is given to a paper tray 22, whereby paper 25 is compressed at the specified pressure to an extraction roller 26 and extracted in regular sequence with rotation of this roller 26 in an arrow direction, pushing up a lever 8 too of a paper detector 1 tightly attached to a support member 27 at the time of being pressed, thus a lead switch 7 and a magnet 17 are parted open. Therefore, a contact of this switch 7 opens, the cassette 19 detects the presence of the paper 25 as the lead switch 7 is a signal of 'open' at the time of a signal showing the presence of the cassette by detection of setting position. Next, when the cassette 19 is thrust into the specified position, an upper surface part of a peripheral wall 21 at the rear end side passes through beneath the lever 8 but it slides on an inclined range of a sliding arm 10 so that the lever 8 retracts therefrom, thus it is operatable without hindrance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a paper detection device for detecting the presence or absence of paper in a paper cassette provided to an automatic paper feeder.

[Background of the invention]

The conventional paper detection device in the cassette uses a microswitch and a rotatable lever, and a slit is attached to the paper tray on which the paper is stacked. Then, the lever above the slit is inserted into the slit, and depending on its rotational displacement, a microswitch is activated to detect the absence of paper, or a reed switch is used instead of the microswitch, and a magnet is attached to the lever. There are various methods, such as moving a magnet toward and away from a reed switch based on the rotational displacement of the lever, and detecting the presence or absence of paper by closing and opening the reed switch.

However, in all of these methods, the displacement of the tip of the lever is detected by converting it into rotational displacement at the support point, and depending on the shape of the lever, an unreasonable force is applied to the support point when the lever is inserted into the slit, causing the lever to change. There is a problem with the formation or the lever coming off. That is, there is a directionality in the direction of the force acting on the lever, and although the action on the lever from the fulcrum direction is performed smoothly, the return direction is often not smooth.

[Purpose of the invention]

An object of the present invention is to reliably detect the presence or absence of paper in a cassette, and to ensure smooth operation at all times without the peripheral wall of the cassette passing under the paper detection device becoming an obstacle.

[Summary of the invention]

The present invention supports the arrow-shaped lever slidably so that the apex of the arrow-shaped lever has a sliding surface inclined in the direction of cassette movement and contacts the paper in the cassette, and is adapted to handle changes in the amount of paper in the cassette. [Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of a paper detection device 1 of the present invention.

A square guide hole 4 is formed in the upper plane 3 of the channel-shaped support member 2.
A reed switch 7 is placed and fixed on the lower plane 5. The arrow-shaped lever 8 is symmetrically provided with sliding arms 10 degrees 10 having left and right inclinations with a vertex 9 in the center. The advancing and retreating direction of the members related to the detected object, especially the paper cassette (arrow 1)
The angles α and α relative to 1) are preferably 45″ or less.

Further, a guide slit 13 of a predetermined length is provided on the vertex 9 side of the central leg 12, and a rectangular guide member 14 of a predetermined length is provided on the other side. The guide member 14 has a branch 15 at a predetermined position.
A magnet 17 is attached to the magnet 17 and operates the reed switch 7.
A holding portion 16 is provided.

The combination of the supporting member 2 and the arrow-shaped lever 8 is made by loosely inserting the guide member 14 into the guide square hole 4, and inserting the screw 18 loosely into the guide slit ', +13 as shown in the figure. Tighten the part to the protrusion 6 which has a female screw,
The arrow-shaped lever 8 is made to move up and down smoothly.

The side cross-sectional view in FIG. 2 is a mounting diagram of the paper detection device 1 of the present invention installed opposite to the paper cassette 19. The paper cassette 19 has a box shape with a peripheral wall 21 attached to a bottom plate 20,
A paper plate 22 is arranged in the first half of the paper plate 22.
Support parts are attached to both rear ends of the holder, and the holder is rotatably suspended at a support point 23.

A coil spring 24 disposed on the bottom plate 20 acts on the front side of the paper plate 22, and when the paper cassette 19 is set at a predetermined position, the paper 25 group placed on the paper plate 22 is moved to an extraction roller for paper extraction. The paper plate 22 is urged to come into pressure contact with the paper plate 26. At that time, the arrow-shaped lever 8 of the paper detection device 1 placed at a predetermined position also detects the paper 25.
The reed switch 7 and magnet 17
are separated, and the contacts of the reed switch 17 are opened.

Paper detection will be described using detailed diagrams of main parts in FIGS. 3 and 4. When the paper cassette 19 is set in a predetermined position, the compressive force applied to the coil spring 24 is applied to the paper plate 22.
(the explanation of the mechanism is omitted), the paper 25 is pressed against the extraction roller 26 at a predetermined pressure, and the extraction roller 26
are sequentially extracted by rotating in the direction of the arrow. paper 2
5 is pressed against the extraction roller 26, the arrow-shaped lever 8 of the paper detection device 1 arranged on the support member 27 of a predetermined device is also pushed up, separating the reed switch 7 and the magnet 17. Therefore, the contact of the reed switch 7 is opened, and the presence of the paper 25 is detected since the reed switch 7 is open when the cassette 19 receives a cassette presence signal based on the detection of the set position. As shown in FIG. 4, after the paper 25 on the paper plate 22 is completely extracted, the tip of the paper plate 22 comes into contact with the extraction roller 26. Furthermore, when the last sheet of paper 25 passes directly under the arrow-shaped lever 8, the slit 22' attached to the paper plate 22 is located at a position opposite to the arrow-shaped lever 8, so that the arrow-shaped lever 8 is inserted into the slit 22'. Immerse yourself. This retraction is stopped by the contact between the reed switch 7 and the holding portion 16 of the magnet 17. At this time, the reed switch 7 is closed, and by detecting this contact state, it is determined that there is no paper. do. If the weight of the arrow-shaped lever 8 is about 3 g, the arrow-shaped lever 8 can be raised by pushing the sliding arm 10 from the horizontal direction with a force of about 20 to 30 g. As for the weight on the paper 25 after being pushed up to a predetermined position, only the pressure of 3 g of the weight of the arrow-shaped lever 8 is applied to the paper 25, so that the paper 25 is not deformed by the arrow-shaped lever 8.

5 and 6 show the state when the cassette 19 is pushed into a predetermined position. At this time, the upper surface of the peripheral wall 21 on the rear end side of the cassette 19 passes under the arrow-shaped lever 8, but as it slides within the slope area of the sliding arm 10 as shown in the figure, the arrow-shaped lever 8 When the cassette 19 is inserted, it is retracted as shown in FIGS. 5 and 6, and it can operate without any trouble. Preferably, the lower end 13' of the guiding slit 13 of the arrow-shaped lever 8 is located at the apex 9.
The closer the arrow-shaped lever 8 is to the upper position, the better, and the closer the apex 9 is to the stepped screw 18, the better. This is effective in making the arrow-shaped lever 8 lighter and moreover operating smoothly.

【Effect of the invention〕

According to the present invention, paper can be reliably detected using the simple arrow-shaped lever as described above, and smooth movement can be obtained even in the passage of members related to the detected object, especially the paper cassette.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of the paper detection device according to the present invention;
The figure is a side view of the mounting state with the paper cassette, Figures 3 and 4 are side views of the main parts for paper detection, and Figures 5 and 6 are side views of the main parts showing the relationship with the cassette peripheral wall. be. 1...Paper detection device, 2...Supporting member, 3...
・Top plane, 4... Guide square hole, 5... Bottom plane, 6
...Protrusion, 7...Reed switch, 8...Arrow-shaped lever, 9...Vertex, 10, 10...Sliding arm,
12...Central leg, 13...Guiding slit, 14.
...Guide member, 15...branch. 16... Holding part, 17... Magnet, 18...
Stepped screw O

Claims (1)

[Claims] 1. A guide slit and a guide member extending from the center leg are attached to the center leg of an arrow-shaped lever having a sliding surface inclined in the direction of cassette movement, and a detection drive element is integrally attached to the guide member. , a detection passive element corresponding to the detection drive element is provided in the guide slit of the arrow-shaped lever and a support member for slidingly guiding the guide member, and the arrow-shaped lever is supported by the support member by driving engagement, so that the arrow-shaped lever is supported by the support member through driving engagement. A paper detection device characterized in that the apex of the shaped lever is brought into contact with the paper surface inside the cassette.