PAPER TRAY UNIT

Abstract

A paper tray unit includes a paper size sensor which is attached to a paper tray and determines a paper size in a paper width direction by detecting a position of a paper width guide. In the paper tray unit, a movable member moves in a paper feed direction accompanying movement of the paper width guide. The position of the paper width guide is detected by the paper size sensor detecting or not detecting the movable member.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a paper tray unit on which a paper is placed to be fed into a paper transportation path. In particular, the present invention relates to a paper tray unit including a paper width guide, which is movably mounted on an upper surface of the paper tray unit in a direction that is substantially perpendicular to a paper feed direction and positions a paper in a paper width direction, and a paper size sensor, which is provided on a reverse surface of the paper tray unit and determines a paper size in the paper width direction by detecting a position of the paper width guide.

2. Description of the Related Art

Many scanners, facsimiles, and copiers or the like have an image scanning device for scanning image information of an original document. One image scanning method used in the image scanning device is a sheet through method, which scans an image by sequentially transporting a plurality of original documents. The sheet through method is mainly used by an Automatic Document Feeder (ADF). FIG. 8 is a schematic longitudinal sectional view of a conventional image scanning device 70 accommodating the ADF. As illustrated in FIG. 8, the image scanning device 70 includes an original document tray unit 71, a paper discharge tray 72, and an ADF 73. An original document 101 to be scanned is placed on the original document tray unit 71. The paper discharge tray 72 is provided directly under the original document tray unit 71. The ADF 73 transports the original document 101 from the original document tray unit 71 onto the paper discharge tray 72. In the image scanning device 70, the original documents 101 stacked on the original document tray unit 71 are separated one sheet at a time from an uppermost sheet by a paper feed unit 74, which defines the ADF 73, and each original document 101 is transported from a paper feed port 75 into an original document transportation path 76. After image information is scanned at a prescribed position in the original document transportation path 76, the original document 101 is discharged from a paper discharge port 77 onto the paper discharge tray 72.

As illustrated in FIG. 8, the original document tray unit 71 includes an original document tray 78, a pair of right and left original document width guides 79, a pinion gear 80, a pair of rack members 81, and paper size sensors 82. The original document 101 is placed on the original document tray 78. The pair of the right and left original document width guides 79 is slidable in a direction orthogonal to a paper feed direction 100, which is shown by an outlined arrow in FIG. 8, on an upper surface of the original document tray 78. The pair of the right and left original document width guides 79 positions the original document 101 in a paper width direction. The pinion gear 80 is rotatably supported on a reverse surface of the original document tray 78. The rack members 81 are respectively integrated with each of the original document width guides 79 and are meshed with the pinion gear 80. The paper size sensor 82 is provided on the reverse surface of the original document tray 78 and determines a size of the original document 101 in the paper width direction. In the above-described structure, when one of the original document width guides 79 slides, the other original document width guide 79 slides in an opposite direction accordingly.

FIG. 9 is an enlarged schematic perspective view of the paper size sensor 82. In the paper size sensor 82, a light-emitting element 83, which emits a light beam, and a light-receiving element 84, which detects the emitted light beam, are arranged to face one another across a detection groove 85. The paper size sensor 82 is a transmissive optical sensor which detects a passage of an object when light is blocked. The paper size sensor 82 has a height dimension H that is larger than a depth dimension D, and is provided with four snap-fits 86 at a base end portion of the paper size sensor 82 for attaching the paper size sensor 82 to the reverse surface of the original document tray 78. As illustrated in FIG. 8, two of the paper size sensors 82 are arranged in the original document tray unit 71 such that a height direction of the paper size sensor 82 extends in a height direction of the original document tray unit 71. Each of the paper size sensors 82 detects a position of each of the original document width guides 79 by detecting or not detecting a rib 87 protruding from each of the rack members 81. Accordingly, a paper size of the original document 101 in the paper width direction can be determined.

However, because of a structure of the conventional original document tray unit 71, the height dimension of the entire ADF 73 increases. Specifically, since the paper size sensor 82 is attached to the original document tray 78 such that the height direction of the paper size sensor 82, which is a direction in which the dimension of the paper size sensor 82 is large, extends in the height direction of the original document tray unit 71, a height dimension of the original document tray unit 71 increases as a whole. Meanwhile, the paper discharge port 77 provided directly under the original document tray unit 71 is required to be positioned at a certain height above the paper discharge tray 72. That is, if a leading edge of the original document 101 touches the paper discharge tray 72 before the original document 101 is completely discharged from the paper discharge port 77, friction is generated between the original document 101 and the paper discharge tray 72, causing a state in which the original document 101 stops without being dropped onto the paper discharge tray 72. In such a state, the next original document 101 may discharge underneath the stopped original document 101, changing an order of the original documents 101, or a paper jam may occur. In order to prevent such problems, an end portion of the original document transportation path 76 is sloped upward, positioning the paper discharge port 77 at a certain height above the paper discharge tray 72. Accordingly, the original document 101 is completely discharged from the paper discharge port 77 before the leading edge of the original document 101 touches the paper discharge tray 72. In the above-described structure of the ADF 73 and the original document tray unit 71, a certain height is required between the paper feed port 75 and the paper discharge port 77 so that the original document 101 discharged from the paper discharge port 77 does not touch the paper size sensor 82. Accordingly, the height dimension of the entire ADF 73 increases, which is not preferable in terms of saving space.

SUMMARY OF THE INVENTION

In order to overcome the problems described above, preferred embodiments of the present invention provide a structure for preventing a discharged original document from touching an original document tray unit, without requiring a large height dimension to be provided between a paper feed port and a paper discharge port by minimizing a height of the original document tray unit.

According to a preferred embodiment of the present invention, a paper tray unit includes a paper tray, a paper width guide, and a paper size sensor. A paper to be fed into a paper transportation path is placed on the paper tray. A paper discharge port of the paper transportation path is provided directly under the paper tray. The paper width guide is arranged on an upper surface of the paper tray to be movable in a direction that is substantially perpendicular to a paper feed direction and determines a position of the paper in a paper width direction. The paper size sensor is attached to a reverse surface of the paper tray and determines a size of the paper in the paper width direction by detecting a position of the paper width guide. In the above-described paper tray, a movable member, which moves in the paper feed direction accompanying movement of the paper width guide, is provided, and a position of the paper width guide is detected by the paper size sensor by detecting or not detecting the movable member.

According to another preferred embodiment of the present invention, in the paper tray unit, a height of the paper size sensor protruding from a reverse surface of the paper tray is within a range in which the paper discharged from the paper discharge port does not touch the paper size sensor.

According to another preferred embodiment of the present invention, in the paper tray unit, the paper size sensor is a transmissive optical sensor which emits a light beam across a detection groove. Further, the movable member passes through the detection groove.

According to another preferred embodiment of the present invention, in the paper tray unit, the paper size sensor has the largest dimension in a height direction of the detection groove and is attached such that the height direction of the detection groove is substantially parallel to the paper tray unit.

According to each of the above-described preferred embodiments of the present invention, in the paper tray unit, the movable member moves in the paper feed direction accompanying the movement of the paper width guide. A paper size in a paper width direction can be determined by the paper size sensor by detecting the movable member. Thus, the paper size sensor can be attached such that a depth direction of the paper size sensor, which has a small dimension, extends in a height direction of the paper tray unit. As a result, a height of the entire paper tray unit can be reduced, and even without providing a long distance between the paper feed port and the paper discharge port, a paper discharged from the paper discharge port can be prevented from touching the paper tray unit. Accordingly, the height dimension of the entire device can be reduced, and space can be saved.

Other features, elements, processes, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the present invention with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view illustrating an exterior of an image scanning device including an original document tray unit according to a first preferred embodiment of the present invention.

FIG. 2 is a schematic plan view illustrating a structure of a reverse surface of an original document tray unit.

FIG. 3 is a schematic plan view illustrating a structure of the reverse surface of the original document tray unit.

FIG. 4 is a schematic plan view illustrating a structure of the reverse surface of the original document tray unit.

FIG. 5 is a schematic plan view illustrating a structure of the reverse surface of the original document tray unit.

FIG. 6 is a schematic perspective view illustrating an attachment state of a rack member, a movable member, a pinion gear, and a paper size sensor.

FIG. 7 is a schematic plan view illustrating a structure of a reverse surface of an original document tray unit according to a second preferred embodiment of the present invention.

FIG. 8 is a schematic perspective view illustrating a reverse surface of an original document tray unit according to a conventional art.

FIG. 9 is a schematic perspective view illustrating an exterior of a paper size sensor according to a conventional art.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Description will be made of an original document tray unit according to preferred embodiments of the present invention with reference to the drawings. FIG. 1 is a schematic perspective view illustrating an exterior of an image scanning device 200 including an original document tray unit 1 according to a first preferred embodiment of the present invention. The image scanning device 200 is mounted on an upper portion of a copy-and-facsimile multi function peripheral or the like, and is used to scan image information of an original document to be copied or to be transmitted by facsimile. The image scanning device 200 includes a device main body 2, an ADF 3, an original document tray unit (a paper tray unit) 1, a paper discharge tray 4, and an operation panel 5. The device main body 2 accommodates an image scanning unit (not illustrated) inside a hollow chassis. The ADF 3 is provided on an upper surface of the device main body 2. The original document (a paper) to be scanned is placed on the original document tray unit 1. The scanned original document is discharged to the paper discharge tray 4. The operation panel 5 is provided on a front surface of the device main body 2 and is used to operate the image scanning device 200.

In the image scanning device 200, when a user issues a start command for a scanning operation by operating the operation panel 5, the original documents stacked on the original document tray unit 1 are picked up one sheet at a time from an uppermost sheet and fed into the ADF 3. The original document is then transported along an original document transportation path (a paper transportation path) in the ADF 3, and the image information of the original document is scanned at a prescribed position in the original document transportation path by the image scanning unit. The scanned original document is transported further downstream through the original document transportation path and discharged onto the paper discharge tray 4 from the paper discharge port (not illustrated) provided directly under the original document tray unit 1.

FIGS. 2 and 5 are schematic plan views illustrating the structure of a reverse surface of the original document tray unit 1. As illustrated in FIGS. 1 and 2, the original document tray unit 1 includes an original document tray 6, a pair of right and left paper width guides 7, a pinion gear 8, a pair of rack members 9A and 9B, a pair of movable members 10A and 10B, and a pair of paper size sensors 11. The original document tray 6 is a paper tray on which the original document is stacked. The pair of the right and left paper width guides 7 is provided on an upper surface of the original document tray 6, on which the original document is placed. The paper width guides 7 position the original document in a paper width direction. The pinion gear 8 is rotatably supported on a reverse surface of the original document tray 6. The rack members 9A and 9B are respectively integrated with the original document width guides 7, and are meshed with the pinion gear 8. The pair of the movable members 10A and 10B moves in a direction that is substantially perpendicular to a moving direction of the rack members 9A and 9B in response to movement of the rack members 9A and 9B. The paper size sensors respectively detect the movable members 10A and 10B.

The original document tray 6 is a flat plate member that is made of plastic, resin etc. As illustrated in FIG. 1, in order to reduce friction by reducing a contact area between the original document tray 6 and the placed original document, a plurality of ribs 12 are arranged to protrude from the upper surface of the original document tray 6 and extending in a paper feed direction 100 shown by an outlined arrow. As illustrated in FIGS. 1 and 2, two elongated holes 13 are formed penetrating through the original document tray 6 and extend in a direction that is substantially perpendicular to the paper feed direction 100. The elongated holes 13 are provided at prescribed intervals in the paper feed direction 100. In addition, position adjustment scales 14 for adjusting a position of the original document width guides 7 are displayed on the upper surface of the original document tray 6 with prescribed intervals between each of the position adjustment scales 14 in a direction that is substantially perpendicular to the paper feed direction 100. The position adjustment scales 14 are symmetrically provided with respect to a center of the original document tray 6 so as to correspond to each of the original document width guides 7. Each distance between the corresponding position adjustment scales 14 is equal to a width of a standard sized paper. In the present preferred embodiment, paper sizes “B5”, “A4”, “B4”, and “A3” according to the Japanese Industrial Standards (JIS) are sequentially displayed outward from the center of the original document tray 6. Both the number and the interval of the position adjustment scales 14 can be changed according to a type of corresponding paper sizes. In addition, for convenience of description, the position adjustment scales 14 to be displayed on the upper surface of the original document tray 6 are shown on the reverse surface of the original document tray 6 in each drawing. As illustrated in FIG. 2, on the reverse surface of the original document tray 6, guide ribs 15 for guiding the rack members 9A and 9B are provided extending in a direction that is substantially perpendicular to the paper feed direction 100.

As illustrated in FIG. 1, the pair of the original document width guides 7 is substantially L-shaped in its longitudinal cross-section. Each of the original document width guides 7 includes a contact portion 16, which makes contact with the upper surface of the original document tray 6, and a standing portion 17, which projects from one side of the contact portion 16 and controls one side edge of the original document in a paper width direction. Each of the original document width guides 7 is provided slidably in a direction that is substantially perpendicular to the paper feed direction 100 on the original document tray 6. In other words, as illustrated in FIG. 2, each of the original document width guides 7 is respectively integrated with each of the rack members 9A and 9B via a connecting member 18, and can slide within an area where the connecting member 18 is guided along the elongated holes 13 of the original document tray 6. Therefore, as illustrated in FIGS. 2 and 5, by sliding each of the original document width guides 7 according to a size of the original document to be scanned, and by adjusting each inner wall surface of the standing portion 17 respectively to a corresponding position adjustment scale 14, a distance between the standing portions 17 of the original document width guides 7 can conform with the size of the original document. In the present preferred embodiment, a pair of the original document width guides 7 is preferably provided, and both of the original document width guides 7 are slidable. However, the present invention is not limited to such an example. For example, a slidable original document width guide 7 may be provided only at one side in a width direction of the original document, and a positioning wall member (not shown) or the like may be fixedly provided on the other side in the width direction of the original document. Accordingly, by sliding the original document width guide 7, both sides of the original document in the width direction can be positioned.

As illustrated in FIG. 6, the pinion gear 8 includes a gear main body 20 having a teethed portion 19 disposed around a circumference of a cylinder member, and a substantially disk-shaped flange 21 protruding in a radial direction of the gear main body 20 located at one end of the gear main body 20. The pinion gear 8 also includes a boss inserting hole 22 penetrating through the gear main body 20 and the flange 21.

As illustrated in FIG. 6, the rack members 9A and 9B include longitudinal flat plate members having a teethed portion 23 at one side of the flat plate member in a width direction. A guide groove 24 is provided on each of the rack members 9A and 9B extending along a longitudinal direction thereof. The guide groove 24 is substantially semicircular in its longitudinal cross-section, and as illustrated in FIG. 2, the guide groove 24 of each of the rack members 9A and 9B has a different planar shape. The guide groove 24 of the rack member 9A includes a first parallel portion 25 and a second parallel portion 26 that extend substantially parallel to a longitudinal direction of the rack member 9A and are displaced in a width direction of the rack member 9A. The guide groove 24 of the rack member 9A also includes a diagonal portion 27 that extends diagonally with respect to the longitudinal direction of the rack member 9A and connects the first and the second parallel portions 25 and 26. Meanwhile, the guide groove 24 of the rack member 9B includes a first parallel portion 28, a second parallel portion 29, and a third parallel portion 30 that extend substantially parallel to a longitudinal direction of the rack member 9B and are connected by a first diagonal portion 31 and a second diagonal portion 32 both extending diagonally with respect to the longitudinal direction of the rack member 9B. With the above-described structure, each of the rack members 9A and 9B is integrated with each of the original document width guides 7 via the connecting members 18.

By detecting a position of the pair of the movable members 10A and 10B, a position of the original document width guides 7 can be detected. As illustrated in FIG. 6, each of the movable members 10A and 10B includes a longitudinal portion 33, which is formed of a longitudinal member, and a flat plate portion 34, which laterally protrudes from one end in the longitudinal direction of the longitudinal portion 33. On a bottom portion of the longitudinal portion 33, a slide groove 35, which is substantially V-shaped in its longitudinal cross-section, is formed extending in the longitudinal direction of the longitudinal portion 33. A fitting projection 36, which fits in the guide groove 24 of the rack member 9A or 9B, protrudes from a top portion of the longitudinal portion 33. On an upper surface of the flat plate portion 34, a projecting detection portion 37 is provided parallel to the longitudinal portion 33.

Next, a description will be made of an attachment structure of the pinion gear 8, the rack member 9B, and the movable member 10B to the reverse surface of the original document tray 6. As illustrated in FIG. 6, a slide rib 38, which is substantially in an inverted V-shape in its longitudinal cross-section in the direction that is substantially perpendicular to the paper feed direction 100, is provided protruding from the reverse surface of the original document tray 6. The movable member 10B can be attached movably along the slide rib 38 by fitting the slide rib 38 in the slide groove 35 formed at the bottom portion of the movable member 10B. From above the movable member 10B, the rack member 9B is attached between the guide ribs 15 shown in FIG. 2 such that the fitting projection 36 of the movable member 10B fits in the guide groove 24 of the rack member 9B, and the rack member 9B can slide along the guide rib 15. Accordingly, accompanying sliding movement of the original document width guide 7 on the upper surface of the original document tray 6, the rack member 9B that is integrated with the original document guide 7 slides on the reverse surface of the original document tray 6. Moreover, as illustrated in FIG. 6, the pinion gear 8 is attached from above the rack member 9B. More specifically, a gear attaching boss 40 with a screw hole 39 is disposed on the reverse surface of the original document tray 6. The pinion gear 8 is attached such that the gear attaching boss 40 is inserted through the boss inserting hole 22, and the teethed portion 19 meshes with the teethed portion 23 of the rack member 9B. Upon inserting the flange 21 into the gear attaching boss 40 until the flange 21 touches the rack member 9B, the pinion gear 8 can be rotatably supported by screwing a screw 41 into the screw hole 39 of the gear attaching boss 40.

In the above-described structure, the pair of the original document width guides 7 slides in opposite directions with respect to one another. In other words, when one of the original document width guides 7 is slid in a direction that is substantially perpendicular to the paper feed direction 100, the rack member 9A, which is integrated with the original document width guide 7, slides in the direction that is substantially perpendicular to the paper feed direction 100 as well, and the pinion gear 8, which is meshed with the rack member 9A, starts rotating. Accordingly, the rack member 9B, which is meshed with the pinion gear 8, slides in the opposite direction of the rack member 9A, and the other original document width guide 7, which is integrated with the rack member 9B, slides in the opposite direction of the former original document width guide 7.

Furthermore, in the above-described structure, each of the movable members 10A and 10B moves accompanying sliding movement of each of the original document width guides 7. More specifically, when the rack member 9B, which is integrated with the original document width guide 7, slides, the fitting projection 36 of the rack member 9B starts moving along the guide groove 24. While the fitting projection 36 is moving along the first parallel portion 28 of the guide groove 24, a force towards the paper feed direction 100 does not act upon the movable member 10B. Therefore, only the rack member 9B slides in the direction that is substantially perpendicular to the paper feed direction 100 without moving the movable member 10B. However, when the fitting projection 36 reaches the first diagonal portion 31 of the guide groove 24, the force towards the paper feed direction 100 acts upon the movable member 10B, and the movable member 10B starts moving along the slide rib 38 in a direction towards the paper size sensor 11. The fitting projection 36 then passes through the first diagonal portion 31, and reaches the second parallel portion 29. Accordingly, since the force towards the paper feed direction 100 stops acting upon the movable member 10B, the movable member 10B stops moving. In the above-described manner, accompanying the sliding movement of each of the original document width guides 7 in the direction that is substantially perpendicular to the paper feed direction 100, each of the movable members 10A and 10B moves in the paper feed direction 100.

The pair of the paper size sensors 11 is used to determine the paper size of the original document by detecting or not detecting each of the movable members 10A and 10B. Since a structure of the paper size sensor 11 is the same as the conventional paper size sensor 82, like reference numerals are used in FIGS. 6 and 9, and a description thereof will be omitted. As illustrated in FIG. 6, the paper size sensor 11 is attached by fitting the snap-fits 86 of the paper size sensor 11 into a sensor mounting portion 42, which is provided on the reverse side of the original document tray 6, under a state in which the paper size sensor 11 is lies flat, i.e., under a state in which the height direction of the paper size sensor 11, which is a direction in which the dimension of the paper size sensor 11 is large, is arranged substantially parallel to the original document tray 6. Accordingly, the light-emitting element 83 and the light-receiving element 84 face each other across a movement path of the movable member 10B. When the projecting detection portion 37 of the movable member 10B is located away from the paper size sensor 11, and light emitted from the light-emitting element 83 is being received by the light-receiving element 84, the paper size sensor 11 sends an ON-signal to a control unit (not shown). On the other hand, while the projecting detection portion 37 of the movable member 10B is located between the light-emitting element 83 and the light-receiving element 84, and light is not being received by the light-receiving element 84, the paper size sensor 11 sends an OFF-signal to the control unit. Thus, passage or non-passage of the movable members 10A and 10B can be detected by the paper size sensors 11.

Accordingly, the movable members 10A and 10B, which move in the direction that is substantially perpendicular to the paper feed direction 100, are detected by the paper size sensor 11, and the paper size sensor 11 can be attached to lie flat. In the above-described structure, the height of the original document tray unit 1 can be reduced as a whole compared with a structure in which the paper size sensor 11 is attached such that the height direction of the paper size sensor 11 extends in the height direction of the original document tray 6. Therefore, the original document discharged from the paper discharge port, which is positioned directly under the original document tray 6, can be prevented from touching the original document tray unit 1. Accordingly, since a long distance is not required to be provided between the paper feed port and the paper discharge port, the height of the ADF 3 can be reduced as a whole.

With reference to FIGS. 2 and 5, description will be made of how the size of the original document in the paper width direction can be determined by the paper size sensor 11. As illustrated in FIGS. 2 and 6, for example, when each of the original document width guides 7 is adjusted to a position adjustment scale 14 indicating A3 size, the movable member 10A has the fitting projection 36 located in the first parallel portion 25 of the rack member 9A and the projecting detection portion 37 located between the light-emitting element 83 and the light-receiving element 84 of the paper size sensor 11. Meanwhile, the movable member 10B has the fitting projection 36 located in the third parallel portion 30 of the rack member 9B and the projecting detection portion 37 located away from both the light-emitting element 83 and the light-receiving element 84 of the paper size sensor 11. Therefore, the control unit determines that the original document placed on the original document tray 6 is size A3 by receiving the OFF-signal from one paper size sensor 11 and the ON-signal from the other paper size sensor 11.

When each of the original document width guides 7 is slid from a position illustrated in FIG. 2 towards the center of the original document tray 6, each fitting projection 36 of the movable members 10A and 10B starts moving along each guide groove 24 of the rack members 9A and 9B respectively. As illustrated in FIG. 3, when each of the original document width guides 7 is adjusted to a position adjustment scale 14 indicating B4 size, the movable member 10A is stopped with the fitting projection 36 still being located in the first parallel portion 25 of the rack member 9A. Accordingly, the projecting detection portion 37 is located between the light-emitting element 83 and the light-receiving element 84. Meanwhile, accompanying movement of the fitting projection 36 of the movable member 10B from the third parallel portion 30 through the second diagonal portion 32 to the second parallel portion 29 of the rack member 9B, the movable member 10B moves in a direction close to the paper size sensor 11, and the projecting detection portion 37 is located between the light-emitting element 83 and the light-receiving element 84. Therefore, the control unit receives an ON-signal from both paper size sensors 11, and determines that the original document placed on the original document tray 6 is size B4.

When each of the original document width guides 7 is slid from a position illustrated in FIG. 3 towards the center of the original document tray 6 to be adjusted to a position adjustment scale 14 indicating A4 size as illustrated in FIG. 4, the movable member 10A moves in a direction away from the paper size sensor 11 accompanying movement of the fitting projection 36 from the first parallel portion 25 through the diagonal portion 27 to the second parallel portion 26 of the rack member 9A, and the projecting detection portion 37 moves away from a position between the light-emitting element 83 and the light-receiving element 84. Meanwhile, the movable member 10B is stopped with the fitting projection 36 still located in the second parallel portion 29 of the rack member 9B, and the projecting detection portion 37 is located between the light-emitting element 83 and the light-receiving element 84. Therefore, the control unit receives the ON-signal from one paper size sensor 11 and the OFF-signal from the other paper size sensor 11, and determines that the original document placed on the original document tray 6 is size A4.

When each of the original document width guides 7 is slid from a position illustrated in FIG. 4 towards the center of the original document tray 6 to be adjusted to a position adjustment scale 14 indicating B5 size as illustrated in FIG. 5, the fitting projection 36 of the movable member 10A stays still in the second parallel portion 26 of the rack member 9A, and the projecting detection portion 37 stays away from the position between the light-emitting element 83 and the light-receiving element 84. Meanwhile, the movable member 10B moves in a direction away from the paper size sensor 11 accompanying movement of the fitting projection 36 from the second parallel portion 29 through the first diagonal portion 31 to the first parallel portion 28 of the rack member 9B, and the projecting detection portion 37 moves away from the position between the light-emitting element 83 and the light-receiving element 84. Therefore, the control unit receives the OFF-signal from both paper size sensors 11, and determines that the original document placed on the original document tray 6 is size B5.

In the above-described preferred embodiment, a total of four types of paper sizes can be determined by the two paper size sensors 11 by detecting the passing or non-passing of the movable members 10A and 10B. However, the present invention is not limited to the above-described preferred embodiment. For example, based on a type of the paper size to be used, a number of the paper size sensors 11 can be increased or decreased, or a plan view of the slide grooves 35 formed on the rack members 9A and 9B can be accordingly changed.

FIG. 7 is a schematic plan view of a structure of a reverse surface of the original document tray unit 50 according to a second preferred embodiment of the present invention, illustrating a state in which the original document width guides 7 are adjusted to the position adjustment scale 14 indicating A4 size. Compared to the original document tray unit 1 of the first preferred embodiment, the structures of rack members 51A and 51B, and movable members 52A and 52B are different in the original document tray unit 50. Since the structure of other members are the same as the structure described in the first preferred embodiment, like reference numerals are used in FIGS. 2 and 7, and a description thereof will be omitted. In the second preferred embodiment, instead of providing the guide grooves 24 on each of the rack members 51A and 51B, shaped cut-out portions 53 are respectively disposed on a side of each of the rack members 51A and 51B opposite the side on which the teethed portion 23 is provided. Each of the cut-out portions 53 of the rack members 51A and 51B has a different planar shape. Meanwhile, the movable members 52A and 52B are blade springs that are made of meandering bent metal plates or the like. A base end portion of each of the movable members 52A and 52B is attached to the reverse surface of the original document tray 6, and an intermediate portion of the movable members 52A and 52B in a longitudinal direction is respectively contacted against the rack members 51A and 51B. While the intermediate portion of the movable members 52A and 52B in the longitudinal direction are contacted against portions other than the cut-out portions 53 of the rack members 51A and 51B, a leading end of the movable members 52A and 52B is located between the light-emitting element 83 and the light-receiving element 84 of the paper size sensor 11. When the rack members 51A and 51B are slid and the intermediate portion of the movable members 52A and 52B in the longitudinal direction are contacted against the cut-out portions 53, the leading end of the movable members 52A and 52B moves in a direction away from the paper size sensor 11 and moves away from the position between the light-emitting element 83 and the light-receiving element 84. Therefore, the control unit receives the ON-signal from one paper size sensor 11 and the OFF-signal from the other paper size sensor 11, and determines that the original document placed on the original document tray 6 is size A4. Although not illustrated in the drawings, in the same manner as the first preferred embodiment, accompanying the sliding movement of each of the original document width guides 7, each of the movable members 52A and 52B moves in the paper feed direction 100 at different timings, and the ON/OFF-signals from the paper size sensor 11 change accordingly. Accordingly, the paper size of the original document placed on the original document tray 6 can be determined.

While the present invention has been described with respect to preferred embodiments thereof, it will be apparent to those skilled in the art that the disclosed invention may be modified in numerous ways and may assume many embodiments other than those specifically set out and described above. Accordingly, the appended claims are intended to cover all modifications of the present invention that fall within the true spirit and scope of the present invention.

Claims

1. A paper tray unit comprising:

a paper tray on which a paper to be fed into a paper transportation path is placed and in which a paper discharge port of the paper transportation path is provided directly under the paper tray;

a paper width guide provided movably in a direction that is substantially perpendicular to a paper feed direction on an upper surface of the paper tray and arranged to position the paper in a paper width direction;

a paper size sensor attached to a reverse surface of the paper tray and arranged to determine a size of the paper in the paper width direction by detecting a position of the paper width guide; and

a movable member arranged to move in the paper feed direction accompanying the movement of the paper width guide.

2. The paper tray unit according to claim 1, wherein a height of the paper size sensor protruding from the reverse surface of the paper tray is within a range in which a paper discharged from the paper discharge port does not touch the paper size sensor.

3. The paper tray unit according to claim 2, wherein the paper size sensor is a transmissive optical sensor which emits a light beam across a detection groove through which the movable member passes.

4. The paper tray unit according to claim 3, wherein the paper size sensor has a maximum dimension in a height direction of the detection groove and is attached such that the height direction of the detection groove is substantially parallel to the paper tray unit.

5. The paper tray unit according to claim 4, wherein each of the paper width guide, the paper size sensor, and the movable member include a pair of paper width guides, a pair of paper size sensors, and a pair of movable members; the paper tray unit includes a pair of rack members integral with the pair of the paper width guides; and the pair of the movable members moves in a direction that is substantially perpendicular to a moving direction of the rack members in response to a movement of the rack members, and a paper size is determined by the pair of the paper size sensors detecting a position of the movable members.

6. The paper size sensor according to claim 5, wherein the pair of the paper width guides is integral with the pair of the rack members via a respective connecting member, and is slidable on the paper tray within a range in which the connecting member is guided along an elongated hole provided on the paper tray.

7. The paper tray unit according to claim 6, wherein the pair of the rack members includes a longitudinal flat plate member and a teethed portion provided at one side in a width direction of the flat plate member.

8. The paper tray unit according to claim 7, wherein a guide groove is provided along a longitudinal direction of each of the rack members, each guide groove is substantially semicircular in a longitudinal cross-section, and each guide groove has a different planar shape.

9. The paper tray unit according to claim 8, wherein the guide groove of a first rack member of the pair of rack members includes a first parallel portion and a second parallel portion extending parallel to the longitudinal direction of the first rack member, the first and the second parallel portions are displaced in a width direction of the first rack member, and a diagonal portion extending diagonally in the longitudinal direction of the first rack member is provided to connect the first parallel portion and the second parallel portion; and

the guide groove of a second rack member of the pair of rack members includes a first parallel portion, a second parallel portion and a third parallel portion extending parallel to the longitudinal direction of the second rack member; and a first diagonal portion and a second diagonal portion extending diagonally in the longitudinal direction of the second rack member are provided to connect the first parallel portion, the second parallel portion, and the third parallel portion.

10. The paper tray unit according to claim 9, wherein a pinion gear is rotatably supported on the reverse surface of paper tray; and the pinion gear includes a gear main body and a substantially disk-shaped flange, the gear main body has a teethed portion formed around a circumference of a cylinder member, the flange is provided at one end of the gear main body and protrudes in a radial direction of the gear main body, and a boss inserting hole is provided through the gear main body and the flange.

11. The paper tray unit according to claim 10, wherein the teethed portions of the rack members and the teethed portion of the pinion gear are meshed with each other, and when the teethed portions of the rack members and the teethed portion of the pinion gear are meshed, the pair of the paper width guides move simultaneously in opposite directions.

12. The paper tray unit according to claim 11, wherein each of the movable members includes a longitudinal portion, a flat plate portion, a fitting projection, and a projecting detection portion; the longitudinal portion includes a longitudinal member, the flat plate portion laterally protrudes from one end of the longitudinal portion, the fitting projection protrudes from a top portion of the longitudinal portion and fits in the guide groove of the rack member, and the projecting detection portion is provided on an upper surface of the flat plate portion.

13. The paper tray unit according to claim 12, wherein a substantially V-shaped slide groove is provided on a bottom portion of the longitudinal portion of the movable member and extends in the longitudinal direction of the longitudinal portion.

14. The paper tray unit according to claim 13, wherein the pair of the paper size sensors includes snap-fits arranged to fit into sensor mounting portions provided on the reverse surface of the paper tray.

15. The paper tray unit according to claim 7, wherein the pair of the rack members includes a shaped cut-out portion arranged on an opposite side in the width direction of the flat plate member from the teethed portion.

16. The paper tray according to claim 15, wherein the cut-out portion on one of the pair of the rack members has a different planar shape from the cut-out portion on the other of the pair of rack members.

17. The paper tray unit according to claim 16, wherein the pair of the movable members include blade springs made of a bent metal plate, a base end portion of the movable members is attached to the reverse surface of the paper tray, and an intermediate portion of each of the movable members in a longitudinal direction contacts against a respective cut-out portion of the pair of the rack members.

18. The paper tray unit according to claim 17, wherein a pinion gear is rotatably supported on the reverse surface of the paper tray, the pinion gear including:

a gear main body having a teethed portion arranged around a circumference of a cylinder member;

a substantially disk-shaped flange provided at one end of the gear main body and protruding in a radial direction of the gear main body; and

a boss inserting hole penetrating through the gear main body and the flange.

19. The paper tray unit according to claim 18, wherein the pair of the paper width guides are arranged to move by the teethed portion of the flat plate member meshing with the teethed portion disposed around the circumference of the cylinder member.

20. The paper tray according to claim 19, wherein the pair of the paper size sensors includes snap-fits arranged to fit into sensor mounting portions provided on the reverse surface of the paper tray.