CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2009-033847 filed Feb. 17, 2009.
BACKGROUND
Technical Field
The present invention relates to an image forming apparatus.
SUMMARY
According to an aspect of the present invention, there is provided an image forming apparatus, including: a main body; a sheet transporting unit provided to a side portion of the main body; and a noise source provided inside of the main body with a rotation portion, wherein the sheet transporting unit includes a plate having a plurality of holes, and an opposing member having a surface opposing the plate, and wherein the noise source, the plate, and the opposing member are disposed in the stated order from inside of the main body to outside of the main body.
BRIEF DESCRIPTION OF THE DRAWINGS
Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein:
FIG. 1 is a cross-sectional view of an image forming apparatus in an exemplary embodiment of the invention;
FIG. 2 is a side cross-sectional view of a sheet reversing/transporting mechanism in the exemplary embodiment;
FIG. 3 is a perspective view of a noise-proof mechanism in the exemplary embodiment;
FIG. 4 is a side cross-sectional view of the noise-proof mechanism in a first modified example of the exemplary embodiment;
FIG. 5 is a perspective view of the noise-proof mechanism in the first modified example of the exemplary embodiment;
FIG. 6 is a plan view of the noise-proof mechanism in a third modified example of the exemplary embodiment;
FIG. 7 is a side cross-sectional view of the noise-proof mechanism in a fourth modified example of the exemplary embodiment;
FIGS. 8A and 8B are each a side cross-sectional view of the noise-proof mechanism in a fifth modified example of the exemplary embodiment;
FIG. 9 is a perspective view of the noise-proof mechanism in a sixth modified example of the exemplary embodiment;
FIGS. 10A and 10B are each a plan view of the noise-proof mechanism in a seventh modified example of the invention;
FIGS. 11A to 11C are each a diagram showing the noise-proof mechanism in an eighth modified example of the exemplary embodiment, and specifically, FIG. 11A is a perspective view thereof, FIG. 11B is a perspective view thereof with a part enlarged, and FIG. 11C is across sectional view thereof;
FIG. 12 is a side cross sectional-view of the noise-proof mechanism in a ninth modified example of the exemplary embodiment cut across a line XII-XII in FIG. 13B;
FIG. 13A is a side cross-sectional view of the noise-proof mechanism in the ninth modified example of the exemplary embodiment;
FIG. 13B is a plan view of the noise-proof mechanism of FIG. 13A;
FIG. 14 is a side cross-sectional view of the noise-proof mechanism in a tenth modified example of the exemplary embodiment;
FIG. 15 is another side cross-sectional view of the noise-proof mechanism in a tenth modified example of the exemplary embodiment, i.e., the noise-proof mechanism of FIGS. 13A and 13B with an open external cover;
FIG. 16 is a side cross-sectional view of the noise-proof mechanism in an eleventh modified example of the exemplary embodiment; and
FIG. 17 is another side cross-sectional view of the noise-proof mechanism in an eleventh modified example of the exemplary embodiment, i.e., the noise-proof mechanism of FIG. 16 with a tilted external sheet feed tray.
DETAILED DESCRIPTION
1. Entire Configuration of Image Forming Apparatus
Now, an exemplary embodiment of the invention will be described with reference to the accompanying drawings. A description is first given of the entire configuration of an image forming apparatus of this exemplary embodiment. In FIG. 1, a reference numeral 10 denotes a main body of an image forming apparatus A. The main body 10 includes an image forming section 20, and the image forming section 20 includes a photosensitive drum, an exposure section, a developing section, and others. The exposure section serves to form an electrostatic latent image on the photosensitive drum, and the developing section serves to develop, using a toner, the photosensitive drum formed with the electrostatic latent image. Above the image forming section 20, a transfer section 30 is disposed close to the image forming section 20, and a toner image formed by the image forming section 20 is primary-transferred to a transfer belt 31 of the transfer section 30.
In the lower portion of the main body 10, a sheet feed section 40 is disposed. In FIG. 1, a reference numeral 41 denotes a tray cassette for paper sheets, and paper sheets (recording sheets) P housed in the tray cassette 41 are picked up one by one from the top by a feed roller 42, and is conveyed by a transporting mechanism 50.
In FIG. 1, a reference numeral 51 denotes a registration roller, against which the tip edge end of the paper sheet P is abutted so that the paper sheet sags between the registration roller 51 and the feed roller 42 in the upstream. The paper sheet P is then straightened before being conveyed. The registration roller 51 is rotated by a registration motor 52. A transfer roller 32 is disposed downstream of the registration roller 51, and by this transfer roller 32, the toner image on the transfer belt 31 is secondary-transferred onto the paper sheet P.
A fixing section 60 is disposed above the transfer section 30. The toner image completed with the secondary transfer onto the paper sheet P is fixed thereto by the heat and pressure coming from a fixing roller 61 of the fixing section 60. Above the fixing section 60, a sheet ejection roller 53 is disposed, which ejects the paper sheet P through with fixing onto a sheet ejection tray 54. Note here that a reference numeral 55 in FIG. 1 denotes a condensation prevention fan, which stirs the air therearound to prevent condensation of the components. A reference numeral 56 denotes a sheet guide, which guides the incoming paper sheet P toward the sheet ejection roller 53.
Next, a reference numeral 70 in FIG. 1 denotes a sheet reversing/transporting mechanism (sheet transporting unit), which turns over the paper sheet P completed with image formation on one surface, thereby making the other surface of the paper sheet P available for image formation. Such a sheet reversing/transporting mechanism 70 is provided with a pair of sheet reversing rollers 71a. When the sheet ejection roller 53 starts rotating in the reverse direction after feeding the paper sheet P to some point on the way, the sheet paper P is directed onto a sheet guide 56 due to its high degree of elasticity, thereby being conveyed to the sheet reversing rollers 71a.
On the downstream side of the sheet reversing rollers 71a, a reversing chute (plate) 72 is provided opposite to an opposing reversing chute (opposing member) 73. At the center portion between these chutes 72 and 73 in the direction of conveying the sheet and the end portion on the downstream side, a pairs of transporting rollers 71b and another pair of transporting rollers 71c are respectively disposed. The pair of sheet reversing rollers 71a and either pair of transporting rollers 71b or 71c is all driving rollers, and the other pair of transporting rollers 71b or 71c is driven rollers. Such driving rollers are rotated by a sheet reversing motor 74.
The paper sheet P conveyed by the transporting rollers 71c is directed to the transfer section 30 after going through a sheet guide 71d. At this point in time, as to the paper sheet P, the surface opposite to the surface already completed with image formation is facing the transfer section 30, and onto the surface, a toner image is secondary-transferred. The toner image as a result of the secondary transfer onto the paper sheet P is then fixed to the paper sheet P by the heat and pressure coming from the fixing roller 61 of the fixing section 60. The paper sheet P is then ejected onto the sheet ejection tray 54 by the ejection roller 53.
2. Configuration of Noise-Proof Mechanism
As shown in FIG. 2, the sheet reversing/transporting mechanism 70 is configured as a piece of unit by an internal cover 75, and an external cover 77, i.e., the external cover 77 is connected to the internal cover 75 so as to freely rotate by a hinge 76. The sheet reversing/transporting mechanism 70 includes therein the holed reversing chute 72 and the opposing reversing chute 73, which configure the noise-proof mechanism in this exemplary embodiment. The sheet reversing/transporting mechanism 70 is also provided therein with the sheet reversing rollers 71a, the transporting rollers 71b and 71c, and the sheet reversing motor 74. In this configuration, the sheet reversing motor 74 is a source of noise. The components, i.e., the sheet reversing motor 74, the holed reversing chute 72, and the opposing reversing chute 73, are disposed in this order from the inside toward the outside of the image forming apparatus A.
As shown in FIG. 3, the holed reversing chute 72 is formed with a plurality of holes 76 at regular intervals both in the vertical and horizontal directions. On the other hand, the opposing reversing chute 73 is configured by a solid plate. The paper sheet P is guided by the internal surface of the holed reversing chute 72 and that of the opposing reversing chute 73, and thus is conveyed toward the lower portion in the drawing.
3. Operation of Image Forming Apparatus
The paper sheets P housed in the tray cassette 41 are picked up one by one by the feed roller 42, and are then each forwarded to the transfer section 30 by the registration roller 51 for secondary transfer. The paper sheet P is then directed to the fixing section 60 for fixing of a toner image thereonto, and is then ejected to the sheet ejection tray 54 by the ejection roller 53. This is the operation for image formation onto one surface of the paper sheet P. For image formation onto both surfaces of the paper sheet P, the sheet ejection roller 53 is rotated in the reverse direction after feeding the paper sheet P to some point on the way. The paper sheet P is then directed onto the sheet guide 56 due to the high degree of elasticity thereof, and then is conveyed toward the sheet reversing rollers 71a. The paper sheet P is then conveyed between the holed reversing chute 72 and the opposing reversing chute 73 by the sheet reversing rollers 71a and the transporting rollers 71b and 71c. After being conveyed as such, the paper sheet P reaches the transfer section 30 after going through the sheet guide 71d, and then is subjected to secondary transfer and fixing similarly to the above before ejection onto the sheet ejection tray 54.
For two-sided image formation, the sheet reversing motor 74 starts rotating. When the sheet reversing motor 74 is a stepping motor, for example, the rotation shaft thereof is of discrete rotation in the high-frequency range, thereby resulting in a high-frequency noise. The concern of such a sheet reversing motor 74 is that the noise thereof is easily leaked to the outside as is disposed in the unit of the sheet reversing/transporting mechanism 70 located closer to the edge of the image forming apparatus A.
In this exemplary embodiment, the noise generated by the sheet reversing motor 74 goes through the holes 76 formed to the holed reversing chute 72, and then is directed to a space between the holed reversing chute 72 and the opposing reversing chute 73. In this space, a resonance is produced, but the noise is reduced as is absorbed in a plurality of holes 76 formed in the holed reversing chute 72. Moreover, because such a resonance space is not closed, some air flow is produced therein, thereby being able to prevent any increase of temperature and occurrence of condensation.
Especially in the above exemplary embodiment, the noise-proof mechanism is configured by the existing components, i.e., the sheet reversing chutes, and one of the chutes is formed with a plurality of holes 76. There is thus no more need to additionally provide any new component such as noise-absorbing member, thereby being able to reduce with effectiveness any noise to be generated therein with no device complexity and no size increase. Note that the noise generating source includes not only the sheet reversing motor 74, but also the registration motor 52 and the condensation prevention fan 55. The noise to be generated by such components can be also reduced by the noise-proof mechanism described above.
4. Modified Example
1. First Modified Example
FIGS. 4 and 5 are each a diagram showing a first modified example of the exemplary embodiment. In this modified example, as an alternative to the opposing reversing chute 73, a plurality of ribs 78 are provided to extend in the vertical direction. These ribs 78 are disposed to the inner surface of the external cover (housing) 77 of the sheet reversing/transporting mechanism 70 configured as a unit. With such a configuration, the paper sheet p is guided between the holed reversing chute 72 and the ribs 78.
Also in such a modified example, the same effects as those in the exemplary embodiment described above can be achieved, i.e., this modified example can achieve the noise-proof effects while preventing any increase of temperature and occurrence of condensation. Moreover, since the existing configuration is utilized, i.e., a plurality of ribs 78 is provided to the inner surface of the external cover 77, there is also no need to additionally provide any new component. Accordingly, the device is not complicated and not increased in size, thereby being able to reduce with good effectiveness any noise to be generated inside.
2. Second Modified Example
In a second modified example, various parameters are set to satisfy the following Expressions 3 and 4, where f denotes the frequency of a noise generated by the sheet reversing motor 74, d denotes the diameter of each of the holes 76 formed in the holed reversing chute 72, a and b respectively denote the center-to-center distance between any adjacent holes 76 in the horizontal and vertical directions, h denotes the thickness of the holed reversing chute 72, and g denotes the distance between the holed reversing chute 72 and the opposing reversing chute 73 from one surface to the surface opposing thereto.
The above Expression 3 is about requirements for attenuating noise in the frequency range of f with most effectiveness. In this modified example, by setting the parameters described above in accordance with the frequency range of a noise to be generated by the noise source, the resulting noise-proof effects can be enhanced to maximum.
3. Third Modified Example
FIG. 6 is a diagram showing a third modified example of the exemplary embodiment. In this modified example, the holed reversing chute 72 is formed with large-diameter holes 76a and small-diameter holes 76b in an alternate manner. The large-diameter holes 76a serve to absorb any noise in the high frequency range, and the small-diameter holes 76b serves to absorb any noise in the low frequency range. Accordingly, in this modified example, even when the reversing motor 74 is set to two values of rotation frequency for high-speed operation and normal operation, the noise-proof effects remain high with both operation speeds.
4. Fourth Modified Example
FIG. 7 is a diagram showing a fourth modified example of the exemplary embodiment. In this modified example, a holed reversing chute 80 is configured to include a vertical plate portion 80a, a tilted plate portion 80b, and a horizontal plate portion 80c. The vertical plate portion 80a extends in the vertical direction, and the tilted plate portion 80b extends from the upper end of the vertical plate portion 80a to diagonally inward, i.e., toward the inside of the main body 10. The horizontal plate portion 80c extends from the upper end of the tilted plate portion 80b in the horizontal direction. With such a configuration, the holed reversing chute 80 partially encloses the sheet reversing motor 74. Opposing to such a holed reversing chute 80, an opposing reversing chute 81 is disposed, which is configured to include a vertical plate portion 81a, a tilted plate portion 81b, and a horizontal plate portion 81c. The vertical plate portion 81a extends in the vertical direction, and the tilted plate portion 81b extends from the upper end of the vertical plate portion 81a to diagonally inward. The horizontal plate portion 81c extends from the upper end of the tilted plate portion 81b in the horizontal direction.
A space A is formed between the vertical plate portion 80a of the holed reversing chute 80 and the vertical plate portion 81a of the opposing reversing chute 81, and a space B is formed between each of the tilted plate portion 80b and the horizontal plate portion 80c and each of the tilted plate portion 81b and the horizontal plate portion 81c. The space B is smaller than the space A. That is, the parameter “g” in the Expression 2 corresponds to the spaces A and B, and thus the portion with the space A is lower in frequency than the portion with the space B. As such, in this modified example, the portion with the space A absorbs any noise in the low frequency range, and the portion with the space B absorbs any noise in the high frequency range. Therefore, even when the sheet reversing motor 74 is set to two values of rotation frequency for high-speed operation and normal operation, the resulting noise-proof effects remain high with the both operation speeds. What is better, any possible noise leakage can be prevented with good effectiveness because these chutes, i.e., the holed reversing chute 80 and the opposing reversing chute 81, are enclosing around the sheet reversing motor 74.
5. Fifth Modified Example
FIGS. 8A and 8B are each a diagram showing a fifth modified example of the exemplary embodiment. The holed reversing chute 72 and the opposing reversing chute 73 in the exemplary embodiment are extending in the vertical direction to be parallel to each other as schematically shown in FIG. 8A. In this modified example, on the other hand, a holed reversing chute 82 remains to extend in the vertical direction. However, an opposing reversing chute 83 is bent at the center portion, and the space C with the holed reversing chute 82 is minimized at the center portion. With such a configuration, the space between the holed reversing chute 82 and the opposing reversing chute 83 is gradually increased in the direction of moving away from each other, i.e., from the center portion in the vertical direction. The space C is set based on the above Expression 2.
In this modified example, because the space Cis set in accordance with the rated operation speed of the image forming apparatus A, with the normal operation, the noise-proof effects can be enhanced to maximum at the portion with the space C. When the operation speed is slowed down due to some reasons, the other portion not including the portion with the space C can satisfactorily enhance the noise-proof effects. That is, in this modified example, because the parameter “g” in the Expression 2 shows a sequential change, even if the noise frequency is reduced due to the unexpected reduction of the operation speed, the noise-proof effects remain high. Note that, in this modified example, the space between the holed reversing chute 82 and the opposing reversing chute 83 may be so set as to be gradually reduced in the direction of moving away from each other, i.e., from the center portion in the vertical direction.
6. Sixth Modified Example
FIG. 9 is a diagram showing a sixth modified example of the exemplary embodiment. In this modified example, a holed reversing chute 84 is formed with a plurality of ribs 85 on the surface on the side of the opposing reversing chute. The ribs 85 are each extending to protrude toward the side of the opposing reversing chute along the direction of conveying the paper sheet P, i.e., vertical direction. The portion of the holed reversing chute 84 where such ribs 85 are not provided is formed with a plurality of holes 76 at regular intervals both in the vertical and horizontal directions.
In this modified example, alternatively, the paper sheet P to be conveyed may be guided by the ribs 85 to reduce any possible resistance during transporting. Herein, the ribs 85 may be provided to the opposing reversing chute.
7. Seventh Modified Example
FIG. 10 is a diagram showing a seventh modified example of the exemplary embodiment. In this modified example, as shown in FIG. 10A, as alternatives to the ribs 85, the holed reversing chute 72 may be formed with an oblong or oval hole 86 in the direction of conveying of the paper sheet P, or as shown in FIG. 10B, the holed reversing chute 72 may be formed with a rhombus hole 87 extending in the direction of conveying of the paper sheet P. In such a modified example, the paper sheet P does not contact with the hole 86 (87) that much when being in contact with the holed reversing chute 72, thereby being able to reduce the resistance therewith.
8. Eighth Modified Example
FIGS. 11A to 11C are each a diagram showing an eighth modified example of the exemplary embodiment. In this modified example, holes 88 are each formed by burring to punch the holed reversing chute 72 from the side of the opposing reversing chute 73. Accordingly, at an edge portion of the holed reversing chute 72 on the side of the opposing reversing chute 73, a beveling R is formed with a cross section of arc.
In this modified example, since the paper sheet P contacts with the beveling R of each of the holes 88, the contact becomes smooth, thereby reducing the resistance.
9. Ninth Modified Example
FIGS. 12 to 13B are each a diagram showing a ninth modified example of the exemplary embodiment. As shown in these drawings, an opposing reversing chute 90 is formed with a plurality of ribs 91 on the surface opposing the holed reversing chute 72. The ribs 91 are extending along the direction of conveying the paper sheet P, i.e., vertical direction, and are formed in two clusters separated in the vertical direction. In the upper cluster, a porous member 92 such as cork is provided not to cover the ribs 91. In such a modified example, any moisture evaporated from the paper sheet P is absorbed by the porous member 92, thereby being able to suppress any occurrence of condensation with good effectiveness.
10. Tenth Modified Example
FIG. 14 is a diagram showing a tenth modified example of the exemplary embodiment. In this modified example, in the first modified example described by referring to FIGS. 4 and 5, the external cover 77 is attached to the main body 10 using a hinge 93 so as to freely rotate. In this modified example, the external cover 77 is configured to freely open and close as such, thereby easing the maintenance and inspection of the noise-proof mechanism configured by the holed reversing chute 72 and others.
11. Eleventh Modified Example
FIGS. 16 and 17 are each a diagram showing an eleventh modified example of the exemplary embodiment. In this modified example, the main body 10 is provided with an external sheet feed tray 100. This external sheet feed tray 100 is configured to include a tray body 101, and an auxiliary tray 102. The auxiliary tray 102 is attached to the tray body 101 to be able to be pulled out therefrom. As shown in FIG. 17, when such an external sheet feed tray 100 is in use, it is tilted by a hinge mechanism that is not shown, and the auxiliary tray 102 is pulled out from the tray body 101 for use with the paper sheets P placed thereon.
In such a modified example, a lattice-like louver 103 (not shown) is formed on the left side surface of the main body, and the air is ejected from the apertures of the lattice-like louver. As a result, any noise to be generated in the main body 10 is also leaked from the apertures. For solving such a problem, in this modified example, the external sheet feed tray 100 is provided with a noise-proof mechanism. That is, in the tray body 101, a plate 101a on the side of the main body 10 is formed with a plurality of holes, and the auxiliary tray 102 serves as an opposing component. In the state of FIG. 16, the noise leaked from the main body 10 goes through the holes and then enters into the space formed by the plate 101a and the auxiliary tray 102, thereby being reduced after being absorbed by the holes.
Note that, in the state of FIG. 16, as an alternative configuration, the auxiliary tray 102 may be pulled out for use. If this is the configuration, the plates 101a and 101b on the both sides of the tray body 101 form a space so that the resulting space is wider in width. Accordingly, any noise in the lower frequency range can be absorbed.
While the invention has been described in detail, it is understood that numerous other modifications and variations can be devised. For example, in the third modified example of FIG. 6, the holes are assumed as varying in diameter, i.e., two diameter sizes of large and small. Alternatively, three or more diameter sizes will allow to deal with a larger range of frequency. Moreover, in the eighth modified example of FIG. 11, the holes are formed by fluing. This is surely not restrictive, and the holes may be formed by normal press punching, and the space between each of the punched portions and a die may be set larger. If this is the case, the resulting holes can be each formed with a beveling R with a cross section of arc.
The invention can be applied to an image forming apparatus such as copier, printer, facsimile device, and a multi-function device serving all of these.
The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.
Patent Application
20100207323
