JPH0797069A - Sheet size detecting device - Google Patents

Abstract

PURPOSE:To detect the size of sheets correctly with simple structure and hardly with mulfunction, without many restrictions on constituent members so as to improve reliability while being low-priced. CONSTITUTION:In a sheet size detecting device for detecting the size of sheets accommodated in a cassette 1, the detected positions of guide members 2, 3 for regulating the end part positions of the sheets are transmitted to a sheet size detecting means 5 by a string member 4 interlocked with the guide members 2, 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting a paper size provided in a paper feeding device, which is used in an image forming apparatus such as a laser printer, a copying machine and a facsimile.

[0002]

2. Description of the Related Art In an image forming apparatus, it is common to make copies on sheets of various sizes as necessary.
A plurality of sheet feeding devices for accommodating sheets are also provided which are suitable for various sizes. However, with the miniaturization of portable type devices and recent devices, it has been performed that sheets of various sizes are alternately replaced for one sheet feeding device. Even when a plurality of sheet feeding devices are prepared, it is often done that the outer dimensions are the same and a guide member that regulates the edge of the sheet is slid to accommodate various sizes of sheets. .

In such a case, after the paper feeding device is mounted on the image forming apparatus, the size of the paper to be stored may not be recognized from the outside. Therefore, various types of devices for detecting the size of the paper provided in the paper feeding device have been conventionally proposed.

For example, in Japanese Patent Laid-Open No. 61-203033, in a paper feed cassette structure in which the paper is regulated and positioned in the lengthwise direction and the widthwise direction, respectively, so as to be able to deal with various sizes of paper, A vertical guide provided with a vertical sliding piece having a plurality of through holes for detection of different sizes,
By using a lateral guide provided with a lateral sliding piece provided with at least one detecting through hole having a size capable of including any of the detecting through holes, by relative movement of the vertical sliding piece and the lateral sliding piece. A configuration is disclosed in which the size of the sheet is detected by detecting the overlapping size of the varying through holes for detection.

Further, for example, in Japanese Unexamined Patent Publication No. 5-105266, a resistor element is formed on the arm front surface interlocking with the width direction guide member and the arm back surface interlocking with the paper feeding direction guide member so as to intersect and contact each other. It is disclosed that the size of the paper is identified from the total resistance value.

In Japanese Patent Laid-Open No. 4-129927, a paper size regulating member that moves in correspondence with a paper size and a moving direction of the paper size regulating member and an uneven portion formed in a direction perpendicular to the moving direction are used. And a plurality of switches provided in a direction perpendicular to the moving direction of the pattern body and moving together with the paper size regulating member, and being turned on / off by the uneven portion, the paper size regulating member There is disclosed a paper size detection device configured to detect the position of the pattern body corresponding to the position of 1 by turning on / off the switch.

Further, as shown in FIG. 9, an arm 21 disposed below the bottom plate of the paper feed cassette 1 has a center of rotation on the bottom plate, and a rear end of the sheet is fed through a long hole 22 provided at one end thereof. It is connected to the part guide member 2. Further, it is also connected to the size detecting means 5 via a long hole 23 provided at the other end. When the guide member 2 is slid along the guide groove 24 in accordance with the sheets to be stored, the arm 21 rotates about its rotation center, shifts the size detection plate of the size detection means 5, and faces the detection plate. Transfer the paper size by moving the relative position to the switch.

[0008]

However, in order to accurately convey the position of the guide member, and thus the sheet size, to the size detecting means by using the mechanism shown in the figure or a rotating member such as a gear, a link mechanism or Since it is necessary to use a special gear or the like, the size detection device has to have a cost problem. Furthermore, in the mechanism as described above,
There are also restrictions on the position and direction in which the movement of the guide member can be transmitted.

Further, in the structure disclosed in Japanese Patent Laid-Open No. 61-203033, "A4" in the case of vertical placement,
"Letter size (8 1/2" x 11 ") and" Legal (8
It is not easy to distinguish "1/2" × 14 ")" due to the restriction of the through holes, and it is difficult to cope with a smaller paper size.

In the configuration disclosed in Japanese Unexamined Patent Publication No. 5-105266, when sheets of the same size are placed with their length and width changed, they cannot be identified and the resistance value changes continuously. Misjudgment may occur due to the deviation of

Therefore, the present invention is to provide a paper size detecting device which has a simple structure, few malfunctions, can accurately detect the size of paper, has less restrictions on the constituent members, is inexpensive, and has improved reliability. It is an issue.

[0012]

According to the present invention, this object is a string size interlocking with a guide member for regulating the end position of a sheet in a sheet size detecting device for detecting the size of a sheet accommodated in a cassette. The member solves the problem by transmitting the detected position of the guide member to the paper size detecting means.

With the movement of the guide member, the string-like member is pulled to one of the two convex portions provided on the guide member,
It is preferable that the paper size is detected from the pulled amount.

The sheet size detecting means generates an identification signal by the movement of the contact point of the two members, and the cord-like member interlocking with the guide member is formed in a ring shape, and the sheet size detection is performed along with the movement of the guide member. It is also convenient that the two members of the means are adapted to move relative to each other.

The sheet size detecting means generates an identification signal by moving the contact points of the two members, and the relative movement direction of the two members of the sheet size detecting means is orthogonal to the attaching / detaching direction of the cassette. It is preferable that

It is preferable that a string-like member is attached to the side of the paper size detecting means in the cassette mounting direction.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the embodiments based on the drawings.

In FIG. 1, the paper feed cassette 1 is provided with a guide member for regulating the position of the paper to be stored on the bottom plate thereof. The guide member includes a trailing edge guide member 2 that regulates the trailing edge of the sheet, and a side guide member 3 that regulates the edge of the sheet along the sheet feeding direction. Each of these guide members is slidable along a guide groove provided in the bottom plate of the cassette, and in the illustrated example, the pair of side guide members 3 can be brought into contact with and separated from each other by a rack and pinion mechanism. . A size detecting means 5 is arranged on the side surface of the cassette 1. Size detection means 5
Is composed of a size detection plate 6 which is movable along the side surface of the cassette 1 and has a predetermined concave and convex shape, and a push switch 7 facing the plate and fixed in position on the main device side. One side guide member 3 and the size detection plate 6 are connected by a thin string member 4. The direction of the thin string member 4 is changed by the convex portion 8 fixed to the bottom plate. The size detection plate 6 of the size detection means 5 is connected to the spring 9 fixed to the cassette 1 on the side opposite to the side connected to the thin cord member 4, and is pulled to the spring side. Tension will be given to 4.

When the side guide member 3 is moved in accordance with the sheets accommodated in the cassette 1, the movement is transmitted to the size detecting plate 6 via the narrow cord member 4, and the size detecting plate 6 also moves. That is, when the side guide members 3 approach each other, the size detection plate 6 moves in a direction against the tensile force of the spring 9, and when the side guide members 3 separate,
The size detection plate 6 moves in the direction pulled by the spring 9. This movement changes the contact position between the size detection plate 6 and the push switch 7, and the paper size is identified by the difference in the signals.

Similar to FIG. 1, in FIG. 2, the paper feed cassette 1 has a bottom plate, on the bottom plate thereof, a rear end guide member 2 and a pair of side guide members 3 for restricting the position of the paper to be stored.
And are provided. On the side surface portion of the cassette 1, there is arranged a size detecting means 5 comprising a size detecting plate 6 which is movable along the side surface and has a predetermined uneven shape, and a push switch 7 which is fixed in position on the main body apparatus side. . One end of the thin cord member 4 is attached to the size detecting plate 6 of the size detecting means, and the other end is fixed to the bottom plate of the cassette 1 behind the rear end guide member 2 in the sheet feeding direction. 4 is caught by the convex portion 8 provided at the lower end of the rear end guide member 2 and the convex portion 8 in the side surface area of the cassette 1, and the size detection plate 6 is moved by the sliding of the rear end guide member 2. The size detecting plate 6 of the size detecting means 5 is connected to the spring 9 fixed to the cassette 1 on the side opposite to the side where the thin string member 4 is attached, and is pulled to the spring side.
As a result, tension is applied to the thin cord member 4.

When the trailing end guide member 2 is moved according to the sheets accommodated in the cassette 1, the convex portion 8 of the trailing end guide member 2 causes the thin cord member 4 to move the size detecting plate 6 against the pulling force of the spring 9. The contact position between the pulling and size detection plate 6 and the push switch 7 changes, and the paper size is identified by the difference in the signals.

As shown in FIG. 2, the rear end guide member 2
Is moved forward along the guide groove from the rearmost position by L, the distance from the fixed end of the thin cord member 4 to the convex portion 8 in the side surface region of the cassette 1 when the guide member 2 is at the rearmost position. C and the distance B from the fixed end of the thin cord member 4 to the convex portion 8 of the guide member 2 when the guide member 2 slides forward.
And the moving distance S of the size detection plate 6 that is equal to the difference (A + B−C) of the sum (A + B) from the convex portion 8 to the convex portion 8 in the side surface region of the cassette 1 have a relationship of S <L. . On the other hand, as shown in FIG. 3, when the thin cord member 4 is bent by the convex portion 8 of the rear end guide member 2 at an acute angle or more, the guide member 2 moves from the intermediate position to the frontmost position. When moving by L, when the guide member 2 is at the intermediate position, the distance D from the fixed end of the thin cord member 4 to the convex portion 8 of the guide member 2 and the convex portion 8 from the convex portion 8 in the cassette side surface region. (C + D) and the distance B from the fixed end of the thin cord member 4 to the convex portion 8 of the guide member 2 when the guide member 2 slides to the frontmost position and the convex portion 8
To the convex portion 8 in the side surface area of the cassette from the sum A (A
The moving distance S of the size detection plate 6 that is equal to the difference (+ A) ((A + B)-(C + D)) has a relationship of S> L. Therefore, by adjusting the positional relationship among the thin cord member 4, the rear end guide member 2, and the convex portion 8 in the side surface area of the cassette, the movement amount of the size detection plate 6 pulled by the thin cord member 4 is set to be larger than that of the guide member. It can be increased or reduced on the contrary, so
The amount of movement of the size detection plate can be arbitrarily set regardless of the amount of movement of the guide member.

The size detection plate 6 and the push switch 7 may be contacted at only one point, but as shown in FIG. 4, the size detection plate 6 having a concavo-convex combination surface and the plate can be contacted. If a plurality of push switches 7 are used to identify the size based on the combination of contact states, more reliable detection becomes possible.

Further, as described above, it is naturally possible to provide a paper size detecting device which simultaneously includes the size detecting means connected to the side guide member and the size detecting means connected to the rear end guide member. By making it possible to detect the vertical and horizontal sizes of the paper at the same time, it is possible to reliably distinguish, for example, B5 horizontal and B4 vertical.

In FIG. 5, the paper feed cassette 1 is provided with a rear end guide member 2 and a pair of side guide members 3 on the bottom plate thereof for regulating the position of the paper to be stored. On the side surface portion of the cassette 1, there is arranged a size detecting means 5 comprising a size detecting plate 6 which is movable along the side surface and has a predetermined uneven shape, and a push switch 7 which is fixed in position on the main body apparatus side. . One end of the thin cord member 4 is attached to the size detecting plate 6 of the size detecting means, the other end is fixed to the bottom plate of the cassette 1, and the thin cord member 4 is provided at the lower end of the rear end guide member 2. A state of passing between the convex portions 8 is formed, and the rear end guide member 2 slides back and forth to be caught on one of the convex portions 8. The size detecting plate 6 of the size detecting means 5 is connected to the spring 9 fixed to the cassette 1 on the side opposite to the side where the thin string member 4 is attached, and is pulled to the spring side.
As a result, tension is applied to the thin cord member 4.

When the trailing end guide member 2 is moved along the guide groove in either of the front-rear direction in accordance with the sheets accommodated in the cassette 1, any one of the convex portions 8 of the trailing end guide member 2 causes the thin string member 4 to move. The size detecting plate 6 is pulled against the pulling force of the spring 9, the contact position between the size detecting plate 6 and the push switch 7 is changed, and the paper size is identified by the difference in the signal. Since the size detection plate 6 is pulled toward the guide member 2 regardless of whether the guide member 2 moves from the reference position to the front-rear direction, the size can be changed between the maximum size and the minimum size of the accommodated paper while the guide member 2 is moved. The amount of movement of the detection plate 6 can be reduced, and the size detection means can be downsized.

Also in FIG. 6, the paper feed cassette 1 is provided with a trailing end guide member 2 and a pair of side guide members 3 on the bottom plate for regulating the position of the paper to be stored. . On the side surface portion of the cassette 1, there is arranged a size detecting means 5 comprising a size detecting plate 6 which is movable along the side surface and has a predetermined uneven shape, and a push switch 7 which is fixed in position on the main body apparatus side. . The thin string member 4 is
Both ends thereof are attached to both side surfaces of the size detecting plate 6, respectively, and convex portions 8 fixed to the bottom plate of the cassette 1 at the front and rear positions of the size detecting means 5 and the guide member 2, respectively.
It is wound around, is stretched in a ring shape, and is also fixed to the bottom portion of the guide member 2. As a result, when the trailing edge guide member 2 is moved in accordance with the sheets accommodated in the cassette 1, the size detection plate 6 moves correspondingly, and the contact position between the size detection plate 6 and the push switch 7 changes. hand,
The paper size is identified by the difference in the signals.

In all of the above embodiments, the size detecting plate of the size detecting means is constructed so as to move along the sheet feeding direction on the side surface of the cassette. In the case where the cassette is set from the paper feeding direction, the size detection plate is under tension, but there is a risk of slipping when mounted. Therefore, as shown in FIG. 7, the sliding direction of the size detecting plate is configured to be orthogonal to the attaching / detaching direction of the cassette. That is, if the location where the thin string member 4 is attached to the size detecting plate 6 is changed by changing the arrangement of the convex portions fixed to the cassette 1, the sliding direction of the size detecting plate 6 changes in the vertical direction.

When the sliding direction of the size detecting plate 6 is parallel to the cassette attaching / detaching direction, the thin cord member 4 is attached to the front side of the size detecting plate 6 in the direction in which the cassette is set, as shown in FIG. Attach the spring 9 to the rear side. By configuring in this way,
When the cassette 1 is attached to the apparatus body, the size detection plate 6
The resistance force that acts on the sheet acts to loosen the thin cord member 4, and the size detection plate 6 can maintain its original position.

[0030]

According to the size detecting device of the first aspect,
Since the detected position of the guide member is transmitted to the paper size detection unit by the string-shaped member that interlocks with the guide member that regulates the end position of the sheet, the string-shaped member can be arranged in a narrow gap or the transmission direction can be changed. The degree of freedom in layout that can be changed arbitrarily can be increased. Further, it is cheaper than the conventional arm members and gears.

In the size detecting device according to the second aspect of the present invention, the cord-like member is pulled by one of the two convex portions provided on the guide member as the guide member moves, and the paper size is detected from the pulled amount. Therefore, it is possible to diversify the setting range of the pull amount within a compact range.

In the size detecting device according to the third aspect, the string-like member interlocking with the guide member is formed in a ring shape, and the two members of the paper size detecting means are relatively bidirectional with the movement of the guide member. Since it is designed to move, even if resistance is applied to the size detecting means when the paper feeding cassette is mounted on the apparatus main body, it can be corrected by the tension of the string-shaped member.

In the size detecting device according to the fourth aspect of the present invention, the relative movement directions of the two members of the paper size detecting means are orthogonal to the attaching / detaching direction of the cassette. Can be prevented from adversely affecting the size detecting means.

In the size detecting device of the fifth aspect, since the string-shaped member is attached to the side of the sheet size detecting means on the cassette mounting direction side, the resistance when the cassette is mounted acts in the direction of slackening the string-shaped member. Therefore, it does not adversely affect the size detecting means.

[Brief description of drawings]

FIG. 1 is a schematic plan view of a paper size detection device according to the present invention.

FIG. 2 is a schematic plan view of a paper size detection device according to another embodiment of the present invention.

FIG. 3 is a schematic diagram illustrating a movement distance of different size detection plates of the paper size detection device corresponding to FIG.

FIG. 4 is a schematic perspective view showing an embodiment of size detecting means.

FIG. 5 is a schematic plan view of a paper size detection device according to another embodiment of the present invention.

FIG. 6 is a schematic plan view of a paper size detection device according to still another embodiment of the present invention.

FIG. 7 is a schematic perspective view showing a configuration in which the sliding direction of the size detection plate is orthogonal to the cassette attachment / detachment direction.

FIG. 8 is a schematic diagram showing one configuration when the sliding direction of the size detecting plate is parallel to the cassette attaching / detaching direction.

FIG. 9 is a schematic plan view of a conventional size detection device.

[Explanation of symbols]

 1 Paper feed cassette 2 Rear end guide member 3 Side guide member 4 Thin cord member 5 Size detection means 6 Size detection plate 7 Push switch 8 Convex portion 9 Spring

Claims (5)

[Claims] 1. A paper size detection device for detecting the size of a paper stored in a cassette, wherein the position of the detected guide member is detected by a string-shaped member that interlocks with a guide member that regulates the end position of the paper. A sheet size detection device characterized by transmitting to a detection means. 2. A paper size is detected from the amount of pulling by pulling the string-like member on one of the two convex portions provided on the guide member as the guide member moves. The paper size detection device according to item 1. 3. A paper size detecting means generates an identification signal by moving a contact point of two members, and a cord-shaped member interlocking with the guide member is formed in a ring shape, and the paper moves in accordance with the movement of the guide member. 2. The paper size detecting device according to claim 1, wherein the two members of the size detecting means move relatively bidirectionally. 4. The paper size detection means generates an identification signal by moving the contact points of the two members, and the relative movement direction of the two members of the paper size detection means is orthogonal to the attachment / detachment direction of the cassette. The paper size detection device according to claim 1, wherein 5. The sheet size detecting device according to claim 1, wherein a string-like member is attached to the side of the sheet size detecting means in the cassette mounting direction.