TWI426045B - Document location limiting mechnism - Google Patents

Description

Document limit mechanism

The invention relates to a document limiting mechanism, in particular to a document limiting mechanism of a paper feeding device of an automatic paper feeding device.

In general, the automatic paper feeding device is used in conjunction with the scanning device to form an automatic scanning device for facilitating automatic scanning of a plurality of documents, or the automatic paper feeding device can be used in conjunction with the printing device to form an automatic printing device. The automatic paper feeder can feed documents of various sizes, of which A4 size documents are most widely used. However, the paper feed cassette of the automatic paper feeding device is usually provided with a file limiting mechanism for placing files of different sizes on the paper tray to limit the position of the document in the center of the paper tray, and avoiding the file being fed. Skewed to cause incomplete scanning or printing.

Please refer to FIG. 1 , which is a structural diagram of a conventional document limiting mechanism disposed on a paper tray. The document limiting mechanism 2 is disposed on one of the paper feed cassettes 1 of an automatic paper feeding device, and the paper feed cassette 1 has a plurality of scales 10, 11 and 12, and the plurality of scales 10, 11 and 12 are disposed in the document limit mechanism. One of the first sides, and the plurality of scales 10, 11 and 12 are exposed on an outer surface 13 of the tray 1, wherein the plurality of scales 10, 11 and 12 are arranged in a row, and the first of the plurality of scales The degree 10 corresponds to the A6 size file, the second scale 11 corresponds to the A5 size file, and the third scale 12 corresponds to the A4 size file. The document limiting mechanism 2 includes a first paper guide 20, a second paper guide 21, and a connecting turntable 22. The first paper guide 20 is disposed on the paper tray 1 and includes a first paper stopper 201 and a first rack 202. The first paper stopper 201 is exposed on the outer surface 13 of the paper tray 1 for blocking documents ( Not shown in one of the first sides, the first rack 202 is disposed on one of the inner surfaces 14 of the tray 1 for contact with the attachment dial 22.

Similarly, the second paper guide 21 is disposed on the paper tray 1 and located on one side of the first paper guide 20, and includes a second paper stopper 211 and a second rack 212. The second paper stopper 211 is exposed to the paper feed. The outer surface 13 of the crucible 1 is for blocking the second side of one of the documents, and the second rack 212 is disposed on the inner surface 14 of the tray 1 for contacting the connecting turntable 22. The connecting turntable 22 is disposed between the first paper guide 20 and the second paper guide 21 for contacting and intermeshing with the first rack 202 of the first paper guide 20 and the second rack 212 of the second paper guide 21, respectively. The first paper guide 20 and the second paper guide 21 are respectively moved in different directions, that is, when the first paper guide 20 moves in a first direction D1, the second guide is made due to the structure of the connection turntable 22. The cardboard 21 moves in a second direction D2 opposite to the first direction D1, and vice versa.

When the user wants to scan an A4-size document, the document limiting mechanism 2 must first be adjusted to conform to the A4-size document by the following steps: moving the first paper guide 20 and using the naked eye to make the first paper guide 20 On the other hand, the second paper guide 21 is moved to the corresponding position in response to the movement of the first paper guide 20. When the user places the A4-size document on the document limiting mechanism 2, the first paper stop 201 of the first paper guide 20 blocks the first side of the document, and the second paper stopper 211 of the second paper guide 21 blocks. The second side of the file, while avoiding files being skewed.

Although the conventional document limiting mechanism 2 has a plurality of scales 10, 11 and 12, the user can adjust the first paper guide 20 according to the size of the document and the plurality of scales 10, 11 and 12 before placing the documents of various sizes. The position of the second paper guide 21. However, many users think that it is quite inconvenient to visually confirm the position of the scale and perform the alignment of the scale. Therefore, a document limit mechanism that does not need to be aligned with the naked eye is introduced on the market.

Please refer to FIG. 2 and FIG. 3 at the same time. FIG. 2 is a schematic structural view of another conventional document limiting mechanism disposed on the paper tray, and FIG. 3 is a schematic bottom view of another conventional document limiting mechanism. The document limiting mechanism 4 is disposed on one of the paper feed cassettes 3 of an automatic paper feeding device, and the paper feed cassette 3 has a plurality of scales 30, 31 and 32, and the plurality of scales 30, 31 and 32 are disposed on the document limit mechanism. One of the first sides, and the plurality of scales 30, 31, and 32 are exposed on an outer surface 33 of the tray 3, wherein the plurality of scales 30, 31, and 32 are arranged in a row, and the first of the plurality of scales The degree 30 corresponds to the A6 size document, the second scale 31 corresponds to the A5 size file, and the third scale 32 corresponds to the A4 size file. In FIG. 3, the paper feed cassette 3 further includes a plurality of grooves 35, 36 and 37 which are disposed on one inner surface 34 of the paper feed cassette 3, and the positions of the first grooves 35 of the plurality of grooves correspond to the first At the position of the scale 30, the position of the second groove 36 of the plurality of grooves corresponds to the position of the second scale 31, and the position of the third groove 37 of the plurality of grooves corresponds to the position of the third scale 32.

The document limiting mechanism 4 includes a first paper guide 40, a second paper guide 41, and a connecting dial 42. The first paper guide 40 is disposed on the paper tray 3, and includes a first paper stopper 401 and a first rack 402. The first paper stopper 401 is exposed on the outer surface 33 of the paper tray 3 to block the document ( Not shown in one of the first sides, the first rack 402 is disposed on the inner surface 34 of the tray 3 for contact with the attachment dial 42. The second paper guide 41 is disposed on the paper tray 3 and located on one side of the first paper guide 40, and includes a second paper stopper 411, a second rack 412, and a protruding portion 413. The second paper stopper 411 is exposed. On the outer surface 33 of the tray 3, it is used to block the second side of one of the documents. The second rack 412 is disposed on the inner surface 34 of the paper tray 3 for contacting the connecting turntable 42, and the protruding portion 413 is close to the plurality of grooves 35, 36 and 37 on the paper tray 3, and When the second paper guide 41 is moved, it projects into the plurality of grooves 35, 36, and 37. The connecting turntable 42 is disposed between the first paper guide 40 and the second paper guide 41 for respectively contacting and engaging with the first rack 402 of the first paper guide 40 and the second rack 412 of the second paper guide 41. The first paper guide 40 and the second paper guide 41 are moved in different directions.

When the user wants to scan an A4 size document, the file limit mechanism 4 must also be adjusted to conform to the A4 size file. First, the user must visually determine the direction corresponding to the third scale 32 of the A4 size and move the second paper guide 41 in the direction in which the third scale 32 is located. During the movement of the second paper guide 41, the projection 413 of the second paper guide 41 projects into the third recess 37 corresponding to the third scale 32. On the other hand, the first paper guide 40 is moved to the corresponding position in response to the movement of the second paper guide 41 such that the first paper stop 401 of the first paper guide 40 blocks the first side of the document, and the second paper guide The second stop 411 of 41 blocks the second side of the document to prevent the document from being skewed.

The conventional document limiting mechanism 4 fixes the position of the second paper guide 41 by extending the protruding portion 413 into the plurality of grooves 35, 36 and 37, so that the user does not need to accurately aim at the naked eye. Available in various sizes. However, the conventional document limit mechanism 4 can only be used for documents of certain sizes (A4, A5, and A6 size documents), and cannot be applied to any size as in the conventional file limit mechanism 2, including unofficial The size of the file. Therefore, there is a need for a document limit mechanism that can be applied to any size without the need for a naked eye alignment.

It is an object of the present invention to provide a document limit mechanism that can be applied to documents of any size without the need for a naked eye alignment.

In a preferred embodiment, the present invention provides a document limiting mechanism for use in a paper feed cassette of an automatic paper feeding device, the document limiting mechanism comprising: a first paper guide disposed on the paper tray For guiding a document into the automatic paper feeding device, and the first paper guide has an extension arm; a second paper guide disposed on the first side of the first paper guide and accessible to the first guide Moving in opposite directions of the cardboard for guiding the document to the automatic paper feeding device with the first paper guide; a connecting turntable disposed between the first paper guide and the second paper guide for respectively a paper guide and the second paper guide are engaged to move the second paper guide in a direction opposite to the first paper guide; and a switching module is disposed on the paper tray for limiting the file The mechanism is changed from a manual positioning mode to a scale positioning mode or the scale positioning mode is changed to the manual positioning mode, the switching module includes: a driving portion having a toggle button and the toggle button is exposed to the paper feed匣, the toggle button is used to Driving the switching module; and a positioning plate adjacent to the driving portion and the positioning plate has a plurality of grooves, and the positioning plate is pushed and moved by the driving portion when the button is toggled, Wherein, when the extension arm extends into the plurality of grooves, the document limiting mechanism is in the scale positioning mode, and when the extension arm is separated from the plurality of grooves, the file limiting mechanism is in the manual positioning mode.

In a preferred embodiment, the positioning plate further includes a plurality of sliding slots, the paper tray includes a plurality of positioning posts disposed on an inner surface of the paper tray, and the plurality of positioning posts respectively extend into the plurality of sliding slots The positioning plate is moved by the toggle button to move in a second direction when the toggle button is toggled in a first direction.

In a preferred embodiment, the first direction forms a 45 degree angle with the second direction.

In a preferred embodiment, when the first paper guide moves in a third direction, the second paper guide moves in a fourth direction opposite to the third direction, and the first direction is perpendicular to the first Three directions and the fourth direction.

In a preferred embodiment, the extension arm further includes a protrusion at one end of the extension arm for extending into any of the plurality of grooves in the scale positioning mode.

In a preferred embodiment, the first paper guide further includes a first paper sheet and a first rack, and the first paper sheet is exposed on an outer surface of the paper tray to block the document. The first side is connected to the first paper piece for engaging with the connecting disk, the second paper guide comprises a second paper piece and a second tooth piece, the second paper piece Formed on the outer surface of the paper tray to block the second side of the document, and the second rack is coupled to the second paper sheet for engaging the connection disk.

In a preferred embodiment, the extension arm and the protrusion are integrally formed with the first rack.

In a preferred embodiment, the connecting turntable further includes: a turntable portion disposed on the inner surface of the paper tray for rotating relative to the first rack and the second rack; and a plurality of serrations And being disposed on the turntable portion for engaging with the first rack and the second rack, so that the turntable portion is rotatable relative to the first rack and the second rack.

In a preferred embodiment, the driving portion further includes a fixing protrusion on an inner surface of the paper tray, and the paper tray includes a first positioning slot and a second positioning slot. a positioning slot is disposed on a first side of the inner surface of the paper tray, and when the document limiting mechanism is in the manual positioning mode, the fixing protrusion protrudes into the first positioning slot; The positioning groove is disposed on the first side of the inner surface of the paper tray and adjacent to the first positioning groove. When the document limiting mechanism is in the scale positioning mode, the fixing protrusion protrudes into the In the second positioning slot.

In a preferred embodiment, the fixing protrusion and the toggle button are integrally formed with the driving portion.

In view of the deficiencies of the conventional document limit mechanism, the present invention provides a document limit mechanism that can improve its deficiencies. Please refer to FIG. 4 and FIG. 5 simultaneously. FIG. 4 is a schematic structural view of the document limiting mechanism of the present invention disposed on the paper tray in a preferred embodiment, and FIG. 5 is a preferred embodiment of the document limiting mechanism of the present invention. A schematic view of a structure disposed on a tray at another viewing angle in the embodiment. The document limiting mechanism 6 is disposed on one of the paper feed cassettes 5 applied to an automatic paper feeding device (not shown), and the paper feed cassette 5 has a plurality of scales 51, 52, and 53, a plurality of scales 51, 52, and 53 is disposed on one of the first sides of the document limiting mechanism 6, and the plurality of scales 51, 52 and 53 are exposed on an outer surface 54 of the paper cassette 5, wherein the plurality of scales 51, 52 and 53 are arranged in a row, and The first scale 51 of the complex scale corresponds to the A6 size document, the second scale 52 corresponds to the A5 size file, and the third scale 53 corresponds to the A4 size file.

Referring to FIG. 5 and FIG. 6 at the same time, FIG. 6 is a schematic diagram showing the structure of the file limiting mechanism of the present invention in a manual positioning mode in a preferred embodiment. In FIG. 6, the paper feed cassette 5 further includes a first positioning groove 56, a second positioning groove 57, and a plurality of positioning posts 58, which are disposed on a first side of one of the inner surfaces 55 of the paper feed cassette. The second positioning groove 57 is disposed on the first side of the inner surface 55 of the paper tray and adjacent to the first positioning groove 56, and the plurality of positioning posts 58 are disposed on the inner surface 55 of the paper tray. In FIG. 5 and FIG. 6 , the document limiting mechanism 6 includes a first paper guide 60 , a second paper guide 61 , a connecting turntable 62 , and a switching module 63 . The first paper guide 60 is disposed on the paper tray 5 for guiding a document (not shown) into the automatic paper feeding device 5, and the first paper guide 60 includes a first paper stopper 601, a first rack 602, and An extension arm 603. The first sheet of paper 601 is exposed on the outer surface 54 of the tray 5 for blocking one of the first sides of the document (not shown), and the first rack 602 is disposed on the inner surface 55 of the tray 5. The extension arm 603 is formed by extending from the first rack 602, and the extension arm 603 has a protrusion 6031 at one end of the extension arm 603. In the preferred embodiment, The extension arm 603 and the projection 6031 are integrally formed with the first rack 602.

The second paper guide 61 is disposed on the paper tray 5 and located on one side of the first paper guide 60, and includes a second paper stopper 611 and a second rack 612. The second paper stopper 611 is exposed on the paper tray 5. The outer surface 54 is configured to block a second side of the document, and the second rack 612 is disposed on the inner surface 55 of the tray 5 for engaging the attachment dial 62. In FIG. 5, the connecting turntable 62 is disposed between the first paper guide 60 and the second paper guide 61, and the connecting turntable 62 includes a turntable portion 621 and a plurality of serrations 622. The turntable portion 621 is disposed on the inner surface of the paper feed cassette 5. 55, the plurality of serrations 622 are disposed on the turntable portion 621 for engaging with the first rack 602 and the second rack 612, so that the turntable portion 621 can be rotated relative to the first rack 602 and the second rack 612 . Due to the connection relationship between the first rack 602, the second rack 612 and the connecting turntable 62, when the first paper guide 60 moves in a third direction D3*, the second paper guide 61 is opposite to the third direction D3*. A fourth direction D4* moves.

Referring to FIG. 5 and FIG. 6 , the switching module 63 is disposed on the paper tray 5 for changing the file limiting mechanism 6 from a manual positioning mode to a scale positioning mode or from a scale positioning mode to a manual positioning mode. . The switching module 63 includes a driving portion 631 and a positioning plate 632. The driving portion 631 has a dial button 6311 and a fixing protrusion 6312. The button 6311 is used to be driven to drive the switching module 63. The knob 6311 is exposed on the tray 5 as shown in FIG. The fixing protrusion 6312 is located on the inner surface 55 of the paper tray 5. In the preferred embodiment, the fixing protrusion 6312 and the dial button 6311 are integrally formed with the driving portion 631.

The positioning plate 632 is disposed on the inner surface 55 of the paper tray 5 and adjacent to the driving portion 631. The positioning plate 632 has a plurality of grooves 6321, 6322, 6323 and a plurality of sliding grooves 6324, and the plurality of sliding grooves 6324 are used for the paper feeding cassette. The plurality of positioning posts 58 on the 5 extend into the direction of movement of the positioning plate 632. When the toggle button 6311 is toggled in a first direction D1*, the positioning plate 632 is pushed by the driving portion 631 and moves in a second direction D2* according to the structure of the plurality of sliding grooves 6324, in the preferred embodiment. The plurality of sliding grooves 6324 are disposed at an angle inclined by 45 degrees with respect to the horizontal line such that a first angle D1* forms a 45 degree angle with the second direction D2*, and the first direction D1* of the movement of the toggle button 6311 is The third direction D3* and the fourth direction D4* of the movement of the first paper guide 60 and the second paper guide 61 are perpendicular to each other.

It should be particularly noted that when the first paper guide 60 moves or the positioning plate 632 moves so that the protruding portion 6031 of the extending arm 603 protrudes into any one of the plurality of grooves 6321, 6322, and 6323, the file limit The mechanism 6 is in the scale positioning mode, and when the projection 6031 of the extension arm 603 is separated from any of the plurality of grooves 6321, 6322 and 6323, the document limiting mechanism 6 is in the manual positioning mode.

Next, the operation of the file limiting mechanism 6 in the manual positioning mode and the scale positioning mode will be described. In FIG. 5 and FIG. 6, the document limiting mechanism 6 is in the manual positioning mode. At this time, the fixing protrusion 6312 of the driving portion 631 protrudes into the first positioning groove 56 of the paper tray 5, and the paper feed cassette 5 The plurality of positioning posts 58 extend into the plurality of sliding slots 6324 of the positioning plate 632, wherein the plurality of positioning posts 58 are located at one of the first ends 6324A of the plurality of sliding slots 6324. When the user wants to scan an A6 size document, the file limit mechanism 6 must be adjusted to conform to the A4 size file. The user first visually determines the direction corresponding to the first scale 51 of the A6 size, and moves the first paper guide 60 in the direction of the first scale 51 while aligning the first paper guide 60 with the naked eye. A scale 51. During the movement of the first paper guide 60, the second paper guide 61 is moved to the corresponding position in response to the movement of the first paper guide 60, so that the first paper stop 601 of the first paper guide 60 blocks the first of the documents. Side, and the second sheet 611 of the second paper guide 61 blocks the second side of the document to prevent the document from being skewed, that is, the operation of the document limiting mechanism 6 in the manual positioning mode is a conventional document. The limit mechanism 2 is the same.

Please refer to FIG. 7 , which is a schematic diagram showing the structure of the file limiting mechanism in the scale positioning mode in a preferred embodiment of the present invention. When the user wants to change the document limiting mechanism 6 to the scale positioning mode, the toggle button 6311 of the driving portion 631 is moved to move in the first direction D1*, so that the fixed protruding portion 6312 of the driving portion 631 is first. The positioning groove 56 is moved to extend into the second positioning groove 57. At this time, the driving portion 631 is pushed against the positioning plate 632 to move the positioning plate 632 in the second direction D2*. Due to the movement of the position plate 632, the plurality of grooves 6321, 6322, and 6323 on the alignment plate 632 are close to the first. The paper guide 60, and the plurality of positioning posts 58 are located at one of the second sliding ends 6324B of the plurality of sliding grooves 6324, so that the document limiting mechanism 6 is in the scale positioning mode, as shown in FIG.

Then, the user only needs to move the first paper guide 60 in the direction corresponding to the first scale 51 of the A6 size. When the first paper guide 60 reaches the first scale 51, the protruding portion 6031 of the extension arm 603 The first groove 6321. corresponding to the first scale 51 is inserted into the first groove 6321. The user can clearly feel the sense of paragraph generated by the protrusion 6031 extending into the first groove 6321. Therefore, the user can determine the first guide. The cardboard 60 and the second paper guide 61 are located at the position corresponding to the A6 document, and need not be aligned with the naked eye, that is, the operation mode of the document limiting mechanism 6 in the scale positioning mode is limited to the conventional document. The bit mechanism 4 is the same.

According to the above, the file limit mechanism of the present invention provides a switching mechanism for changing the operation mode of the file limit mechanism. When the document limiting mechanism is in the scale positioning mode, it can conform to the operation mode in which some user preferences do not visually align the first paper guide and the scale. When the file limiting mechanism is in the manual positioning mode, the user can freely move the first paper guide and the second paper guide without restricting the file limit mechanism to only place files of a certain size. Therefore, the document limiting mechanism of the present invention can be applied to documents of any size, and can be aligned with the naked eye without being aligned with the naked eye, and can simultaneously meet the needs of different users.

The above are only the preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Therefore, any equivalent changes or modifications made without departing from the spirit of the present invention should be included in the present invention. Within the scope of the patent application.

1, 3, 5. . . Paper feed

2, 4, 6. . . Document limit mechanism

10, 30, 51. . . First scale

11, 31, 52. . . Second scale

12, 32, 53. . . Third scale

13, 33, 54. . . Outside the paper tray

14, 34, 55. . . Inner surface of the tray

20, 40, 60. . . First paper guide

21, 41, 61. . . Second guide paper

22, 42, 62. . . Connection turntable

35, 6321. . . First groove

36, 6322. . . Second groove

37, 6323. . . Third groove

56. . . First positioning slot

57. . . Second positioning slot

58. . . Positioning column

63. . . Switching module

201, 401, 601. . . First sheet of paper

202, 402, 602. . . First rack

211, 411, 611. . . Second sheet of paper

212, 412, 612. . . Second rack

413. . . Protrusion

603. . . Extension arm

621. . . Turntable

622. . . Serrated

631. . . Drive department

632. . . Positioning plate

6031. . . Protrusion

6311. . . Toggle button

6312. . . Fixed projection

6324. . . Sliding slot

6324A. . . First end of the sliding groove

6324B. . . Second end of the sliding groove

D1, D1*. . . First direction

D2, D2*. . . Second direction

D3*. . . Third direction

D4*. . . Fourth direction

FIG. 1 is a schematic structural view of a conventional document limiting mechanism disposed on a paper tray.

FIG. 2 is a schematic structural view of another conventional document limiting mechanism disposed on a paper tray.

3 is a schematic bottom view showing the structure of another conventional document limiting mechanism.

4 is a schematic view showing the structure of the document limiting mechanism of the present invention disposed on a paper tray in a preferred embodiment.

FIG. 5 is a schematic view showing the structure of the document limiting mechanism of the present invention disposed on a tray at another viewing angle in a preferred embodiment.

FIG. 6 is a schematic diagram showing the structure of the document limiting mechanism of the present invention in a manual positioning mode in a preferred embodiment.

FIG. 7 is a schematic bottom view showing the structure of the document limiting mechanism of the present invention in a scale positioning mode in a preferred embodiment.

5. . . Paper feed

6. . . Document limit mechanism

55. . . Inner surface of the tray

56. . . First positioning slot

57. . . Second positioning slot

58. . . Positioning column

60. . . First paper guide

61. . . Second guide paper

62. . . Connection turntable

63. . . Switching module

602. . . First rack

612. . . Second rack

603. . . Extension arm

621. . . Turntable

622. . . Serrated

631. . . Drive department

632. . . Positioning plate

6031. . . Protrusion

6311. . . Toggle button

6312. . . Fixed projection

6321. . . First groove

6322. . . Second groove

6323. . . Third groove

6324. . . Sliding slot

Claims (10)

A document limiting mechanism is applied to a paper feeding device of an automatic paper feeding device, the document limiting mechanism comprises: a first paper guiding plate disposed on the paper tray for guiding a document into the automatic paper feeding The first paper guide has an extension arm; a second paper guide disposed on a first side of the first paper guide and movable in a direction opposite to the first paper guide for the first a guide paper guides the document into the automatic paper feeding device; a connecting turntable is disposed between the first paper guide and the second paper guide for respectively engaging the first paper guide and the second paper guide Moving the second paper guide in a direction opposite to the first paper guide; and a switching module disposed on the paper tray for changing the document limiting mechanism from a manual positioning mode to a scale positioning The mode is changed from the scale positioning mode to the manual positioning mode, the switching module includes: a driving part having a toggle button and the dial button is displayed on the tray, the dial button is used to be dialed Driving the switching module; and a positioning plate adjacent to the driving portion and the positioning plate has a plurality of grooves, and the positioning plate is pushed and moved by the driving portion when the toggle button is toggled, wherein the extending arm extends into the plurality of concave portions When the slot is in the slot, the file limiting mechanism is in the scale positioning mode, and when the extension arm is disengaged from the plurality of grooves, the file limiting mechanism is in the manual positioning mode. The document limiting mechanism of claim 1, wherein the positioning plate further comprises a plurality of sliding grooves, the paper tray comprises a plurality of positioning columns disposed on an inner surface of the paper tray, the plurality of positioning columns And extending into the plurality of sliding slots respectively, so that the positioning plate is pushed by the toggle button to move in a second direction when the toggle button is toggled in a first direction. The document limiting mechanism of claim 2, wherein the first direction forms a 45 degree angle with the second direction. The document limiting mechanism of claim 2, wherein when the first paper guide moves in a third direction, the second paper guide moves in a fourth direction opposite to the third direction, and The first direction is perpendicular to the third direction and the fourth direction. The document limiting mechanism of claim 1, wherein the extension arm further comprises a protrusion at one end of the extension arm for extending into the plurality of grooves in the scale positioning mode a groove. The document limiting mechanism of claim 5, wherein the first paper guide further comprises a first paper sheet and a first rack, the first paper sheet being exposed on an outer surface of the paper tray The first rack is connected to the first sheet for engaging with the connecting disc, and the second paper guide comprises a second sheet and a second a rack, the second sheet of paper is exposed on the outer surface of the tray for blocking the second side of the document, and the second rack is coupled to the second sheet for connecting with the second sheet The turntable is engaged. The document limiting mechanism of claim 6, wherein the extension arm and the protrusion are integrally formed with the first rack. The document limiting mechanism of claim 6, wherein the connecting turntable further comprises: a turntable portion disposed on the inner surface of the paper tray for relative to the first rack and the second a rack rotation; and a plurality of serrations disposed on the dial portion for engaging the first rack and the second rack such that the dial portion is relative to the first rack and the second rack Turn. The document limiting mechanism of claim 1, wherein the driving portion further comprises a fixing protrusion on an inner surface of the paper tray, and the paper tray comprises a first positioning groove and a second positioning slot, the first positioning slot is disposed on a first side of the inner surface of the paper tray, and when the document limiting mechanism is in the manual positioning mode, the fixing protrusion extends into the first positioning slot a second positioning groove is disposed on the first side of the inner surface of the paper tray and adjacent to the first positioning groove, when the file limiting mechanism is in the scale positioning mode, The fixing protrusion extends into the second positioning groove. The document limiting mechanism according to claim 9, wherein the fixing protrusion and the button button are integrally formed with the driving portion.