This application claims priority from Japanese Patent Application No. 2015-253971, filed on Dec. 25, 2015, which is incorporated herein by reference in its entirety.
Aspects described herein relate to a sheet conveying device.
A known sheet conveying device is configured to reduce acoustic noise generated during sheet conveyance. The sheet conveying device is used in a dot line printer and includes upper and lower paper guides which are made of sheet metal and define a sheet travelling passage therebetween. A noise absorbing material is disposed along at least one of the upper and lower paper guides, which has a plurality of holes, so as to be exposed through the holes to the sheet travelling passage.
Another known sheet conveying device includes a sheet guide which defines a sheet transport path and has Helmholtz tubes. The frequency of acoustic noise to be absorbed is adjustable according to the type of a sheet.
It may be beneficial to provide a sheet conveying device configured to reduce acoustic noise, generated during sheet conveyance, in a wide range of frequencies without using a noise absorbing material.
According to one or more aspects of the disclosure, a sheet conveying device comprises a tray, a conveying unit configured to convey a sheet to the tray, a wall member, a structural member, and a frame. The wall member has a first surface and a second surface opposite to the first surface. The first surface and the tray define a first space. The structural member has a facing surface which faces the second surface of the wall member. The frame has a wall surface which defines, together with the second surface of the wall member and the facing surface of the structural member, a second space. The wall member has a plurality of through holes formed therethrough and including a first through hole and a second through hole. A first imaginary plane containing an edge of the first through hole in the second surface is away from the facing surface of the structural member by a first distance, and a second imaginary plane containing an edge of the second through hole in the second surface is away from the facing surface by a second distance which is different from the first distance.
According to one or more aspects of the disclosure, a sheet conveying device comprises a tray, a conveying unit configured to convey a sheet to the tray in a conveying direction, a wall member, a structural member, and a frame. The wall member has a first surface and a second surface opposite to the first surface. The first surface and the tray define a first space. The structural member has a facing surface which faces the second surface of the wall member. The frame has a wall surface which defines, together with the second surface of the wall member and the facing surface of the structural member, a second space. The wall member includes a perforated portion having a plurality of though holes through which the first space and the second space communicate with each other. The perforated portion has a surface segment which is a part of the second surface. The surface segment and the facing surface of the structural member are inclined relative to each other. The plurality of through holes include a first through hole and a second through hole which are located at different positions in the conveying direction.
Aspects of the disclosure are illustrated by way of example and not by limitation in the accompanying figures in which like reference characters indicate similar elements.
An illustrative embodiment according to one or more aspects of the disclosure will be described below. The disclosure is merely an example and various changes, arrangements and modifications may be applied therein without departing from the spirit and scope of the disclosure. A top-bottom direction 7 may be defined with reference to an orientation of a multifunction device 10 that may be disposed in an orientation in which it may be intended to be used (refer to
[Overall Configuration of Multifunction Device 10]
As shown in
The scanner 11 may be a flatbed scanner. Details of the scanner 11 will be omitted here. The printer 12 includes a conveying device 27 and a recording unit 24 (refer to
The conveying device 27 includes a casing 14 defining a conveying path 23 therein, feed trays 19, 20 (refer to
As shown in
The casing 14 has an opening 13 at the front face 22. The opening 13 is defined above the feed tray 20. Details of the opening 13 will be described later.
As shown in
As shown in
In the illustrative embodiment, the feed tray 19 is disposed below the feed tray 20. The feed tray 19 is configured similarly to the feed tray 20. The feed tray 19 includes a bottom plate and a pair of side plates. The feed tray 19 functions similarly to the feed tray 20. The printer 12 records an image on a sheet 15 fed from the feed tray 19 similarly to when the printer 12 records an image on a sheet 15 fed from the feed tray 20. Therefore, the feed tray 19 is omitted from the figures other than
The conveying path 23 extends from a rear end of the feed tray 20 upward to form a U-turn, and extends frontward to the discharge tray 21. The conveying path 23 is defined by a first guide member 31 and a second guide member 32 which face each other with an interval therebetween. A sheet 15 is fed from the feed tray 20 to the conveying path 23 and conveyed along the conveying path 23 in a conveying direction 16 shown by a dotted line with arrows in
A conveying roller pair 63 and a discharge roller pair 66 are disposed inside the casing 14. Specifically, the conveying roller pair 63 is disposed at the conveying path and upstream of a recording unit 24 in the conveying direction 16. The conveying roller pair 63 includes a conveying roller 61 and a pinch roller 62. The pinch roller 62 is pressed against a roller surface of the conveying roller 61 by an elastic member (not shown) such as a spring. The discharge roller pair 66 is disposed at the conveying path and downstream of the recording unit 24 in the conveying direction 16. The discharge roller pair 66 includes a discharge roller 64 and a spur 65. The spur 65 is pressed against a roller surface of the discharge roller 64 by an elastic member (not shown) such as a spring. Upon reception of driving force from the motor 76, the conveying roller 61 and the discharge roller 64 rotate while pinching a sheet against the pinch roller 62 and the spur respectively, thereby to convey a sheet 15 in the conveying direction 16.
The recording unit 24 is disposed inside the casing 14. Specifically, the recording unit 24 is disposed above the conveying path 23. The recording unit 24 includes a recording head 37 and a carriage 38 holding the recording head 37. The recording head 37 includes nozzles 36 for ejecting ink toward a platen 67. The ink is supplied from an ink cartridge (not shown). The platen 67 is a plate-like member for supporting thereon a sheet 15 conveyed along the conveying path 23. The platen 67 is disposed below the conveying path 23 to face the recording head 37. The carriage 38 is supported by a frame disposed inside the casing 14 to reciprocate in the right-left direction 9. When the carriage reciprocates, the recording head 37 ejects ink through the nozzles 36 toward a sheet 15 conveyed on the platen 67 along the conveying path 23, thereby to record an image on the sheet 15. In the illustrative embodiment, the recording unit 24 employs an inkjet recording method but may employ an electrophotographic recording method.
[Discharge Tray 21]
The discharge tray 21 is supported by the feed tray 20 and insertable into and removable from the casing 14 unitarily with the feed tray 20. In other words, the discharge tray 21 is supported by the casing 14 via the feed tray 20. The discharge tray 21 may be supported directly by the casing 14.
A sheet 15 supported by the feed tray 20 is fed by the feed roller 25 to the conveying path 23 and conveyed by the conveying roller pair 63 to the recording unit 24 which performs image recording. The sheet 15 having an image recorded thereon is conveyed forward by the discharge roller pair 66 to be discharged onto the discharge tray 21.
[Right Wall Member 81, Left Wall Member 82, and Upper Wall Member 83]
As shown in
The right wall member 81 is shaped like a flat plate extending in the top-bottom direction 7 and in the front-rear direction 8. A front end of the right wall member 81 is connected to the front face of the casing 22. A left-facing surface of the right wall member 81 is defined as a left surface 81A, and a right-facing surface of the right wall member 81 is defined as a right surface (not shown). The left surface 81A extends, in the top-bottom direction 7, from right ends of the feed trays 19, 20 and the discharge tray 21. The left surface 81A of the right wall member 81 extends to a position above the discharge tray 21.
The left wall member 82 is shaped like a flat plate extending in the top-bottom direction 7 and in the front-rear direction 8. A front end of left wall member 82 is connected to the front face of the casing 22. A right-facing surface of the left wall member 82 is defined as a right surface 82A, and a left-facing surface of the left wall member 82 is defined as a left surface (not shown). The left surface 81A of the left wall member 82 extends, in the top-bottom direction 7, from left ends of the feed trays 19, 20 and the discharge tray 21. The left surface 81A extends to a position above the discharge tray 21. The feed trays 19, 20 are in contact with the left surface of 81A of the right wall member 81 and the right surface 82A of the left wall member 82.
The upper wall member 83 is shaped like a flat plate extending substantially in the front-rear direction 8 and in the right-left direction 9. The upper wall member 83 is connected to an upper end of the right wall member 81 and an upper end of the left wall member 82. The upper wall member 83 has a substantially uniform thickness in the top-bottom direction 7. The upper wall member 83 has a lower surface 83A which faces down toward the discharge tray 21, and an upper surface 83B which faces up and is opposite to the lower surface 83A. The lower surface 83A of the upper wall member 83 is an example of a first surface, and the upper surface 83B is an example of a second surface. The upper wall member 83 is inclined such that a front end portion 83C is higher than a rear end portion 83D. The front end portion 83C is positioned at a substantially same position as an upper edge of the opening 13.
As shown in
As shown in
[Ribs 85]
As shown in
[Electronic Board 86]
As shown in
[Shield Plate 87]
As shown in
[First Space 90]
A first space 90 is defined in the multifunction device 10 substantially by the receiving surface 21A of the discharge tray 21, the lower surface 83A of the upper wall member 83, the left surface 81A of the right wall member 81, the right surface 82A of the left wall member 82, the opening 13, and the discharge port 84.
[Second Space 92]
As shown in
A second space 92 is defined substantially by the lower surface 88A of the shield plate 87, the lower surface 91A of the lower frame 91, the upper surface 83B of the upper wall member 83, a front wall 14D of the casing 14, a front surface 95C (an example of a wall surface) of the vertical plate portion 95B of the inner frame 95, a left surface 14B (refer to
[Third Space 93]
In the multifunction device 10, a third space 93 is defined behind an imaginary plane containing a rear surface 95D of the vertical plate portion 95B of the inner frame 95. The conveying unit 27 is disposed in the third space 93. The third space 93 is positioned closer to the rear of the casing 14 than the first space 90. The third space 93 and the first space 90 communicate with each other via the discharge port 84.
[Through Holes 94]
As shown in
An imaginary plane 96 containing edges of the through holes 94 in the foremost row on the upper surface 83B of the upper wall member 83 is away, by a first distance D1, from the lower surface 88A of the first plate segment 88 of the shield plate 87. An imaginary plane 96 containing edges of the through holes 94 in the middle row on the upper surface 83B of the upper wall member 83 is away, by a second distance D2, from the lower surface 88A of the first plate segment 88 of the shield plate 87. An imaginary plane 96 containing edges of the through holes 94 in the rearmost row on the upper surface 83B of the upper wall member 83 is away, by a third distance D3, from the lower surface 88A of the first plate segment 88 of the shield plate 87. The distance D1 is smaller than the distance D2. The Distance D2 is smaller than the distance D3. Hereinafter, a distance in the top-bottom direction 7 between an imaginary plane 96, which contains an edge of a through hole 94 on the upper surface 83B of the upper wall member 83, and the lower surface 88A of the first plate segment 88 of the shield plate 87 may be merely referred to as a “distance between the through hole 94 and the lower surface 88A of the shield plate 87”.
[Helmholtz Resonance]
Sound or acoustic noise having a particular frequency may be absorbed using the Helmholtz resonance effect. Helmholtz resonance occurs in a container with an aperture, where air inside the container acts as a spring and air inside the aperture acts as mass.
[Application of Helmholtz Resonance]
In the multifunction device 10, the second space 92 is a cavity having a plurality of apertures which are the though holes 94. The second space 92 may be considered as an assembly of a plurality of Helmholtz resonators. Accordingly, it may be considered that acoustic noise generated by the conveying unit 27 in the third space 93, which is to be emitted to an exterior of the multifunction device 10 from the opening 13 through the first space 90, is absorbed by a structure including the second space 92 and the through holes 94.
The resonant frequency f [Hz] of a Helmholtz resonator in the multifunction device 10 is given by the following equation:
where c [m/s] is the speed of sound; P is the aperture ratio; δ is the end correction; l [m] is the thickness of a through hole 94, and L [m] is the thickness of the cavity, which is considered as the distance between the through hole 94 and the lower surface 88A of the shield member 87.
Assume, as shown in
When the distance L from an imaginary plane containing an edge of a through hole 94 to the lower surface 88A of the first plate segment 88 varies from one point to another point of the edge, an average distance should be calculated using the area ratio of the imaginary plane. For example, suppose that a first region of an edge of a though hole has an area ratio r1 to the total area of the edge of the through hole and a distance from an imaginary plane containing each point, in the first region, of the edge of the though hole to the lower surface 88A is d1, and suppose that a second region of an edge of a though hole has an area ratio r2 to the total area of the edge of the through hole and a distance from an imaginary plane containing each point, in the second region, of the edge of the though hole to the lower surface 88A is d2. In this case, the distance L is calculated as an average distance by r1×d1+r2×d2. However, instead of the calculating an average distance, the distance L may be obtained by measuring from a central position of an imaginary plane containing an edge of a though hole 94 to the lower surface 88A, or the distance L may be set to a distance by which most of points of an edge of a through hole are away from the lower surface 88A. For example, when the upper surface 83 B having through holes 94 is inclined at a constant angle, a distance from a central position of an imaginary plane containing an edge of one of the through holes 94 to the lower surface 88A may be considered as the distance L from an imaginary plane containing the edge of the one of the through holes to the lower surface 88A.
In the multifunction device 10, the upper wall member 83 is inclined such that the front end portion 83C, which is adjacent to the opening 13, is positioned above the rear end portion 83D in the top-bottom direction 7. Thus, a though hole 94 positioned closer to the front is away from the first plate segment 88 of the shield plate 87 by a smaller distance in the top-bottom direction 7. In other words, the distance D1 is smaller than the distance D2 which is smaller than the distance D3. Each of the distances D1, D2, and D3 corresponds to the thickness L of a cavity of a Helmholtz resonator. Thus, a through hole 94 positioned closer to the front is associated with a cavity having a smaller thickness L. The multifunction device 10 has a plurality of cavities which are associated with respective through holes 94 and have different thicknesses L. Thus, it is considered that the multifunction device 10 absorbs acoustic noise with a plurality of resonant frequencies F which correspond to a plurality of thicknesses L.
[Effects Obtained by Illustrative Embodiment]
According to the illustrative embodiment, the multifunction device 10 has the second space 92 which is almost closed and defined by the upper surface 83B of the upper wall member 83, the lower surface 88A of the shield plate 87, the front surface 95C of the inner frame 95, and the inner surface of the casing 14. The second space 92 communicates with the first space 90 via the through holes 94. Thus, the structure formed by the upper wall member 83, the shield plate 87, the inner frame 95, and the casing 14 is considered similar to the structure of a Helmholtz resonator. An imaginary plane containing an edge of a through hole 96 closer to the opening 13 is away from the lower surface 88A of the shield plate 87 by a smaller distance. This allows the multifunction device 10 to simultaneously absorb acoustic noise with a plurality of frequencies which correspond to a plurality of distances between the through holes 96 and the lower surface 88A. Consequently, the multifunction device 10, which is not provided with a noise absorbing material, reduces acoustic noise in a wide range of frequencies.
The front end portion 83C of the lower surface 83A of the upper wall member 83 is farther from the discharge tray 21 than the rear end portion 83D. The space above the discharge tray 21 is wider at the front than at the rear. This allows a user to take a sheet 15 from the discharge tray 21 readily through the opening 13.
The through holes 94 are located within a particular area of the upper wall member 83. The particular area faces the lower surface 88A of the shield plate 87 in the top-bottom direction 7. Air passes through the through holes 94 between the first space 90 and the second space 92. Thus, air heated by the heat emitted by the electronic board 86 is emitted out of the second space 92 via the through holes 94 and gaps. This facilitates effective heat emission from the electronic board 86.
The electronic board includes the CPU 79, which is relatively heat-emitting and heat-sensitive as compared to other electronic elements and an integral circuit (IC). At least a part of the through holes 94 is located in the upper wall member 83 to face an area of the electronic board 86 occupied by the CPU 79. This facilitates effective heat emission from the CPU 79.
Each of the though holes 94 is oval and a dimension thereof in the front-rear direction 8 is larger than a dimension in the right-left direction 9. The through holes 94 are likely to prevent a sheet 15, when discharged onto the discharge tray 21, from getting stuck in the through holes 94.
The through-holes 94 are formed only at the left-front area of the upper wall member 83a and no through-holes are formed at the remaining area. The though holes 94, which are partially formed in the upper wall member 83, are less likely to reduce the strength of the upper wall member 83.
The upper wall member 83 includes the ribs 85 which protrude from the lower surface 83A toward the discharge tray 21 and extend in the front-rear direction 8. The through holes 94 are located adjacent to the ribs 85. The ribs 85 are likely to prevent a sheet 15 from approaching the through holes 94 and prevent a sheet 15, when discharged onto the discharge tray 21, from getting stuck in the though holes 94. Also, the ribs 85 extending in the front-rear direction 8 are likely to prevent a sheet 15 from getting stuck at the ribs 85.
The upper wall member 83 and the inner frame 95 define the first space 90, the second space 92 in which the electronic board 86 and the shield plate 87 are located, and the third space 93 in which the motor 76 and the conveying roller pair 63 are located. Acoustic noise generated by the motor 76 and the conveying roller pair 63 leaks from the third space 93 to the first space 90 and vibrates air in the through holes 94 to thereby resonate with the air. Consequently, this structure absorbs the acoustic noise and reduces leakage of the acoustic noise to an exterior of the multifunction device 10 through the opening 13.
[Variations]
According to the above-described illustrative embodiment, as shown in
For example, as shown in
Alternatively, as shown in
Alternatively, although no figure is shown, an upper wall member 83 and a shield plate 87 may be disposed obliquely at different angles.
Instead of disposing the upper wall member 83 and the shield plate 87 such that distances between through holes 94 and the shield plate 87 simply increase or decrease when viewed from the rear to the front, an upper wall 83 and a shield plate 87 may be configured such that distances between through holes 94 and the shield plate 87 irregularly increase and decrease when viewed from the rear to the front.
Other than the shield plate 87 and the electrical plate 86, a structural member such as the casing 14, a cover, or a frame of the multifunction device 10 may face the through holes 94 in the top-bottom direction 7.
In the illustrative embodiment shown in
When the right wall member 81 has the through holes 94, the right wall member 81, a left surface 81A, and a right surface 81B are examples of a wall member, a first surface, and a second surface, respectively. In this case, a mostly closed space 97 (as an example of a second space) is defined to the right of the right wall member 81. A surface (as an example of a facing surface) of a structural member, e.g., an inner surface 14A of a casing 14, faces the right surface 81B of the right wall member 81 to define the space 97. One of the through holes 94 is away, by a distance D1, from the inner surface 14A, and another one of the through holes 94 is away, by a distance D2, from the inner surface 14A. The distance D1 is different from the distance D2.
When the left wall member 82 has the through holes 94, the left wall member 82, a right surface 82A, and a left surface 82B are examples of a wall member, a first surface, and a second surface, respectively. In this case, a mostly closed space 98 (as an example of a second space) is defined to the left of the left wall member 82. A surface (as an example of a facing surface) of a structural member, e.g., the inner surface 14A of the casing 14, faces the left surface 82B of the right wall member 82 to define the space 98. One of the through holes 94 is away, by a distance D1, from the inner surface 14A, and another one of the through holes is away, by a distance D2, from the inner surface 14A. The distance D1 is different from the distance D2.
In the illustrative embodiment shown in
The through holes 94 may not be necessarily provided under the electronic board 86 and the shield plate 87. When neither the electronic board 86 nor the shield plate 87 are provided, resonant frequencies depend on distances between respective through hole 94 and a structural member, such as the casing 14, a cover, or a frame of the multifunction device 10, disposed vertically above the through holes 94.
The through holes 94 may be positioned arbitrarily, instead of being positioned at a portion of the upper wall member 83. For example, the through holes 94 may be distributed across a wide area of the upper wall member 83.
The second space 92 in the illustrative embodiment shown in
While the disclosure has been described in detail with reference to the specific embodiments thereof, these are merely examples, and various changes, arrangements and modifications may be applied therein without departing from the spirit and scope of the disclosure.
Number | Date | Country | Kind |
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2015-253971 | Dec 2015 | JP | national |
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