JP2007193269A - Exterior case - Google Patents

Abstract

To provide an exterior case that is easy to manufacture and that can be reduced in size, and that can suppress noise leaking from a joint between exterior plates.
An exterior case in which a plurality of exterior plates (11, 12) are connected to accommodate a noise generating source so that the main surfaces of the plurality of exterior plates (11, 12) face each other. A passage portion S1 serving as a gap through which air flows is formed, and a portion of the exterior plates 11 and 12 superimposed in the middle of the passage portion S1 is thinned to have a larger space than the gap. An internal space 20 was formed.
[Selection] Figure 2

Description

  The present invention relates to an exterior case that houses a noise generation source inside.

Electronic devices such as printers and copiers have a complicated drive mechanism that generates vibration, and this drive mechanism is accommodated in an outer case formed by connecting a plurality of outer plates.
FIG. 9 is a schematic cross-sectional view showing a cross section of a joint portion of such an exterior case. As shown in this figure, the vibration of the drive mechanism vibrates air to produce sound energy E, and this sound energy E leaks outside through the gap S formed at the joint of the exterior case and becomes noise. For this reason, generally, a sound absorbing material is arranged inside the outer case to absorb noise.

  However, downsizing of electronic devices in recent years is remarkable, and the space for arranging the sound absorbing material is decreasing, and the sound absorbing material cannot be sufficiently arranged. In addition, since the inside of an electronic device such as a laser printer often generates heat, simply placing a sound absorbing material causes heat to accumulate inside. For this reason, each manufacturer is trying to reduce the noise by improving the drive mechanism, but there is a limit to the noise reduction.

FIG. 10 is a view aiming at a soundproof effect by devising the exterior case for such a situation, and is a schematic sectional view showing a cross section of a joint portion of the exterior case (for example, see Patent Document 1). .
The exterior case of this figure has a long path through which air passes by disposing the end portions of the two exterior plates 1 and 2 in the vicinity of the joint so that the concave and convex portions mesh with each other. To bend. As a result, noise leaking to the outside can be reduced.

Published Utility Model Gazette of Japanese Utility Model Publication No. 7-39097

  However, as shown in FIG. 10, in the structure in which the end of the outer case has a comb-teeth shape, when the outer case is manufactured, a high processing accuracy is required. There is also a risk that the outer panels cannot be joined together. And in order to make it the structure which meshes | engages mutually, a convex-shaped part is formed and the thickness of a joint will become large.

  The present invention is for solving the above-described problems, is easy to manufacture, can be downsized, and can further suppress noise leaking from the joints of the exterior plates. The purpose is to provide.

  According to the first aspect of the present invention, there is provided an exterior case in which a plurality of exterior plates are connected to accommodate a noise generation source, the main surfaces of the plurality of exterior plates being connected to each other. Are formed so as to face each other, forming a passage portion that becomes a gap through which air flows, and by reducing the thickness of a part of the overlaid exterior plate in the middle of the passage portion, a larger space than the gap is formed. This is achieved by an exterior case that forms an internal space.

According to the configuration of the first aspect of the present invention, the main surfaces of the plurality of exterior plates are overlapped so as to face each other, and a passage portion that becomes a gap through which air flows is formed. Passes through the passage and is discharged to the outside.
Then, an internal space having a larger space than the gap is formed in the middle of the passage portion. For this reason, the cross-sectional area of the passage portion is widened or narrowed. Therefore, the sound energy is efficiently converted into thermal energy by expansion and compression when passing through the passage portion, and noise leakage can be suppressed.
Moreover, the structure for forming such a passing portion having an internal space is easy to manufacture because the thickness of a part of the overlaid exterior plate is reduced in the middle of the passing portion. Further, unlike the conventional case, no convex portion is formed on the exterior plate, so that it is possible to deal with a downsized product.
Thus, as an effect of the present invention, it is possible to provide an exterior case that is easy to manufacture and can be reduced in size, and that can suppress noise leaking from the joint of the exterior plate.

According to a second aspect of the present invention, in the configuration of the first aspect, the internal space is formed by forming recesses in both of the stacked exterior plates, and arranging the openings of both recesses to face each other. It is characterized by being.
According to the configuration of the second invention, the internal space is formed by forming recesses on both of the stacked exterior plates and arranging the openings of both recesses to face each other. For this reason, since the volume of the internal space is larger than when the recess is formed in only one of the plurality of exterior plates, the expansion and compression rate of the sound energy can be increased. Therefore, the soundproofing effect can be enhanced.
Further, since the internal space is formed by arranging the openings of the concave portions provided in both the exterior plates so as to face each other, even if the volume is increased as described above, The strength of the exterior plate can be ensured without excessively reducing the thickness of either one of the exterior plates.

According to a third invention, in the configuration of the first or second invention, the internal space is a groove formed along a direction perpendicular to a direction in which air flows from the inside to the outside. Is characterized by having a substantially rectangular cross section and a groove width of about 4 mm.
According to the configuration of the third aspect of the invention, the internal space is a groove formed along a direction perpendicular to the direction in which air flows from the inside to the outside, and has a substantially rectangular cross section. However, in the case of such a groove, it was found from experiments that the soundproofing effect is high when the groove width is 4 mm, and that the soundproofing effect does not change much even if this groove exceeds 4 mm. Therefore, by setting the groove width to about 4 mm, it is possible to suppress the area of the portion where the end portions of the exterior plate are overlapped as much as possible without making the groove width insignificant while achieving the best soundproof effect. it can.

1 and 2 show an outer case 10 for a printer as an example of an outer case according to an embodiment of the present invention. FIG. 1 is a schematic perspective view of the outer case 10, and FIG. It is A line cut sectional drawing.
As shown in this figure, the exterior case 10 generates noise by connecting a plurality of exterior plates 11, 12, 13 that can be visually recognized in the drawing and a plurality of exterior plates on the back side that are not shown. Comes with a source.

Specifically, each of the exterior plates 11, 12, 13 is formed from a resin molded product such as ABS resin, and the thickness D1 thereof is about 2 mm.
The exterior case 10 includes a plurality of exterior plates 11, 12, 13, and the like that are connected to each other by metal fittings (not shown), and is generally a hexahedron that seals a noise generation source. That is, in consideration of maintenance, recycling, and the like, the exterior plates 11, 12, and 13 are not joined with an adhesive or the like, but are connected so as to be easily disassembled or removed.

  For this reason, a gap is easily formed at the joint between the plurality of exterior plates, and sound energy generated from a noise generation source such as a motor or a gear leaks outside through the gap and becomes noise. Therefore, in the case of the present embodiment, the following configuration is used in order to make it difficult for sound energy generated from the noise generation source to leak to the outside.

  That is, for example, the joint between the exterior plate 11 and the exterior plate 12 will be described. As shown in the partial enlarged view surrounded by the alternate long and short dash line in FIG. 1 and the main surface of the exterior plates 11 and 12 as shown in FIG. The passage part S1 is formed as a gap through which air flows. In addition, the partial enlarged view enclosed with the dashed-dotted line of FIG. 1 has shown the exterior board 11 and the exterior board 12 away from actual for convenience of an understanding.

Specifically, since the joint of the exterior plates 11 and 12 corresponds to the corner of the exterior case 10, the main surfaces of the end portions 11a and 12a of the exterior plates 11 and 12 are bent by bending the end portion 11a of the exterior plate 11. Are stacked so as to face each other.
In the case of this embodiment, the region where the main surfaces of the end portions 11a and 12a are opposed to each other is formed in substantially the entire area in the height H1 direction of the exterior case 10, and the printer shown in FIG. In the case of the case, they are overlapped over a height of about 250 mm. Further, the width W1 of the overlapped region is preferably at least twice the plate thickness D1 of the exterior plates 11 and 12 so that an internal space S1 described later can be formed with a sufficient volume. In this embodiment, the width W1 is about 7 mm. Yes.

  And the dimension of the clearance W2 of the passage part S1 formed by overlapping the main surfaces of the end parts 11a, 12a of the exterior plates 11, 12 so as to face each other is about 0.5 mm. The part S1 communicates the inside and the outside of the outer case 10. For this reason, the sound energy (air vibration) E generated from the noise generation source leaks to the outside through the passage portion S1. In addition, the smaller the dimension of the gap W2 of the passage part S1, the better.

Here, in the middle of the passage portion S1, an internal space 20 having a larger space than the gap W2 is formed by reducing the thickness of part of the stacked exterior plates 11 and 12.
Specifically, the internal space 20 is formed by forming recesses on the smooth surfaces in contact with the passage portions S1 of the end portions 11a, 12a of the stacked exterior plates 11, 12 by injection molding, pressing, or the like. Thus, the dimension of the gap formed when the end portions 11a and 12a are overlapped has a relatively small portion and a large portion. In the case of this embodiment, this recessed part is formed one each in both the edge parts 11a and 12a with which the exterior board was piled up.

The internal space 20 is provided in substantially the entire region where the end portions 11a and 12a are overlapped so that the sound energy E always passes through the internal space 20 when passing from the inside to the outside of the exterior case 10. In the case of the present embodiment, the groove is formed along a direction (height H1 direction in FIG. 1) perpendicular to the direction in which air flows from the inside to the outside (left-right direction in FIG. 2). Yes. And about the groove | channel which comprises this internal space 20, the cross section is made into the substantially rectangular shape, and the groove width W3 (length in the direction where air flows outside from the inside) is about 2 mm.
Moreover, the area | region where the internal space 20 of the passage part S1 is not provided is equal in size with the internal space 20 interposed therebetween, and in the present embodiment, the two internal spaces 20 are interposed therebetween. The length in the direction in which air flows from the inside to the outside is divided into three equal parts, and each width W4 is about 1 mm.

The exterior case 10 according to the embodiment of the present invention is configured as described above, and the passage portion S1 serving as a gap through which air flows is formed by overlapping the main surfaces of the plurality of exterior plates 11 and 12 to face each other. Therefore, the sound generated from the noise generation source becomes air vibration and leaks outside through the passage S1. At this time, since an internal space 20 having a space larger than the gap is formed in the middle of the passage portion S1, the cross-sectional area of the passage portion S1 is increased or decreased. Therefore, the sound energy is efficiently converted into thermal energy by expansion and compression when passing through the passage S1, and leakage of noise can be suppressed.
Further, the passing portion S1 having such an internal space 20 is formed by simply stacking the main surfaces of the plurality of exterior plates 11 and 12 so as to face each other, and reducing the thickness of a part of the overlapped portions. Therefore, manufacturing is also easy and it can respond to size reduction of a product.

  In the case of the present embodiment, as shown in FIG. 1, the noise level meter K is installed in front of the exterior plate 12 having a manual paper feed panel, and before the passing portion S1 having the internal space 20 as described above is provided. When the noise after installation was measured, a sound pressure drop of about 2 dB was observed before and after that.

FIG. 3 and FIG. 4 are diagrams relating to a soundproof characteristic experiment conducted in order to investigate what kind of internal space 20 is provided in the passage portion S1 to exhibit a soundproofing effect. FIG. FIG. 4 is a cross-sectional view of the vicinity of the passage portion S1.
As shown in Fig. 3, the experiment prepared a hexahedral test box made of a transparent acrylic plate with a thickness of 10mm, and built-in a speaker for acoustic excitation, and pink noise was constant from this speaker. It was done at a volume of.

  Moreover, as shown in FIG. 3, the main surfaces of the end portions of the two plate members 25 and 26 made of ABS resin having a thickness of 2 mm are opposed to the through hole provided in the central portion of one surface of the experimental box. The sound level meter was placed at a position spaced a predetermined distance from the overlapped region ER. At this time, the above-described passage portion S1 is formed by overlapping the main surfaces of the two plate members 25 and 26 so as to face each other, and the two plate members 25 and 26 constituting the passage portion S1 are formed. The dimension of the gap was 0.5 mm. In addition, as shown in FIG. 3, the length L1 of the area | region ER where these two board | plate materials 25 and 26 overlapped was 10 cm.

Then, how much the sound pressure decreases compared to the case where the internal space 20 is not formed in the passage portion S1 and the case where the two internal spaces 20 in which the width W3 and the depth D2 shown in FIG. Was measured. The result is the data shown in FIG. That is, the negative value in the table of FIG. 5 is a measurement result when the internal space 20 is not formed from the measurement result when the internal space 20 with various changes in the width W3 and the depth D2 is formed in the passage portion S1. The value obtained by subtracting the result indicates that the greater the minus value, the higher the soundproofing effect.
In the experiment in which the internal space 20 is formed in the passage portion S1, the internal space 20 is in the direction of the length L1 of the region ER in which the two plate members 25 and 26 shown in FIG. The groove is provided along the direction perpendicular to the direction of flow from the outside to the outside, and the cross section thereof is substantially rectangular as shown in FIG. Further, the width W4 in which the internal space 20 of the passage portion S1 is not provided is set at three locations, and each is set to 1 mm.

As a result, as shown in FIG. 5, it was found that the greater the depth D2 of the internal space (groove) 20, the lower the sound pressure and the lower the noise.
On the other hand, when the width W3 of the internal space (groove) 20 exceeds 4 mm, it has been found that there is almost no decrease in sound pressure and no increase in the soundproofing effect is observed.
As a result, the width W3 of the internal space (groove) 20 is set to about 4 mm, so that the width W3 of the internal space (groove) 20 is not increased meaninglessly while the soundproofing effect is in the best state. , 26 can be suppressed as much as possible.

  In addition, when the dimension in the width direction of the internal space (groove) 20 (direction in which air flows from the inside to the outside) is 2 mm and the dimension in the depth direction of the internal space (groove) 20 is 1.2 mm, the internal space ( Groove) 20 in the same direction as the width direction (the direction in which air flows from the inside to the outside) is divided into a semicircular shape, a triangular shape, and a hexagonal half shape. I measured it. As a result, when the semicircular shape is used, the sound pressure is reduced by about 1.9 dB, when the triangular shape is obtained, the sound pressure is reduced by about 1.7 dB, and when the half shape is formed, the sound pressure is reduced by about 1.6 dB. Was recognized. From this, it was found that the larger the cross-sectional area of the internal space (groove) 20, the greater the soundproofing effect.

FIG. 6 is a schematic cross-sectional view of a portion of the exterior case 30 according to the first modification of the embodiment of the present invention, in which main surfaces of a plurality of exterior plates are overlapped. In this figure, the portions denoted by the same reference numerals as those used in the embodiment of FIGS. 1 and 2 have a common configuration, and therefore, a duplicate description will be omitted, and hereinafter, differences will be mainly described.
The outer case 30 of FIG. 6 is mainly different from the outer case 10 of FIGS. 1 and 2 in the form of the internal space 20.

That is, the exterior case 30 is not a corner portion but a smooth portion, and the passage portions S1 are formed by overlapping the main surfaces of the plurality of exterior plates 11 and 12 so as to face each other.
And the internal space 20 provided in the middle of this currency part S1 forms the recessed parts 31 and 32 in both the laminated | stacked exterior plates 11 and 12, and the opening part of both these recessed parts 31 and 32 mutually opposes. Are arranged and formed.

In addition, the recesses 31 and 32 are grooves along a direction perpendicular to the direction in which air flows from the inside to the outside, like the grooves shown in the diagram surrounded by the one-dot chain line in FIG. And the cross-sectional shape of the groove | channel is each semicircular shape as shown in FIG. 6, Comprising: The recessed part 31 of one exterior board 11 and the recessed part 32 of the other exterior board 12 overlap, and internal space 20 Is formed in a substantially circular shape.
The internal space 20 is provided at three locations.

The exterior case 30 according to the first modification of the embodiment of the present invention is configured as described above, and the internal space 20 forms the recesses 31 and 32 in both of the stacked exterior plates 11 and 12, Both the recesses 31 and 32 are formed so as to be opposed to each other. Therefore, since the volume of one internal space 20 becomes larger than forming a recess in only one of the plurality of exterior plates 11, 12, the expansion and compression rate of the sound energy E is increased, and the soundproofing effect is obtained. Enhanced.
Further, since the internal space 20 is formed by arranging the openings of the recesses 31 and 32 provided in both of the stacked exterior plates 11 and 12 so as to face each other, the volume is increased as described above. Even if the soundproofing effect is enhanced, it is possible to ensure the strength of the exterior plates 11 and 12 without excessively reducing the thickness of one of the stacked exterior plates 11 and 12.

FIG. 7 is a schematic cross-sectional view of a portion of the exterior case 40 according to the second modification of the embodiment of the present invention, in which the main surfaces of a plurality of exterior plates are overlapped. In this figure, the portions denoted by the same reference numerals as those used in the embodiment of FIGS. 1 and 2 have a common configuration, and therefore, a duplicate description will be omitted, and hereinafter, differences will be mainly described.
The outer case 40 of FIG. 7 is mainly different from the outer case 10 of FIGS. 1 and 2 in the form of the passage portion S1 and the internal space 20.

That is, the exterior case 40 has a passage portion S1 formed in a smooth portion, like the exterior case 30 of FIG. 6, but the one exterior plate 11 is bent into a crank shape inside the exterior case 40. The passage portion S1 is formed by overlapping the principal surface on the outer surface side of the bent end portion 11a with the principal surface on the inner surface side of the end portion 12a of the other exterior plate 12 facing each other. .
In addition, the internal space 20 of the exterior case 40 is a groove like a groove shown in a diagram surrounded by a one-dot chain line in FIG. And the cross-sectional shape of the groove | channel is a half shape of a hexagon as shown in FIG. 7, One location is on one exterior plate 11, and 2 locations on the other exterior plate 12, respectively, and air is inside from the outside, respectively. The flow directions are provided so as not to overlap (that is, a narrow gap is always formed outside the internal space 20).

  The exterior case 40 according to the second modification of the embodiment of the present invention is configured as described above, and one of the plurality of exterior plates 11 and 12 is bent into a crank shape, Since the main surface of the end portion is overlapped with the main surface of the other exterior plate 12 so as to face the main surface of the end portion, a smooth surface can be formed without forming a stepped portion on the surface of the exterior case 40. . And by making one exterior plate 11 into a crank shape, the distance from the inside through which the air of the passage part S1 passes to the outside can be lengthened, and the sound energy E is converted to heat energy by the length of the length. Thus, the soundproofing effect can be enhanced.

  In addition, in order to make the surface of the exterior case 40 a smooth surface, as shown in FIG. 8, which is a schematic cross-sectional view showing another modification of the embodiment of the present invention, not the structure shown in FIG. Both the exterior plates 11 and 12 may be bent at right angles to the inside of the exterior case 50, and the principal surfaces of the folded end portions 11a and 12a may be stacked so as to face each other. Further, at that time, in the passage portion S1 formed by overlapping the end portions 11a and 12a, the opening portions of the concave portions formed in both the exterior plates 11 and 12 are opposed to each other as in FIG. Of course, it may be arranged.

  The present invention is not limited to the above-described embodiment. Each configuration of each embodiment and each modification may be combined or omitted as appropriate, and may be combined with other configurations not shown. For example, although the above-mentioned embodiment illustrated the exterior case for printers, the present invention is not limited to the printer.

1 is a schematic perspective view of an exterior case for a printer as an example of an exterior case according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line AA in FIG. 1. The whole schematic diagram regarding the soundproof characteristic experiment of the internal space provided in a passage part. Sectional drawing of the passage part vicinity of FIG. The data which shows the result of the soundproof characteristic experiment of FIG. It is an exterior case which concerns on the 1st modification of embodiment of this invention, Comprising: The schematic sectional drawing of the part which accumulated the main surfaces of the some exterior board. It is an exterior case which concerns on the 2nd modification of embodiment of this invention, Comprising: The schematic sectional drawing of the part which accumulated the main surfaces of the several sheets of exterior board. The schematic sectional drawing which shows the other modification of embodiment of this invention. The schematic sectional drawing which showed the cross section of the part of the joint of the conventional exterior case. It is a figure of the exterior case aiming at the conventional soundproof effect, and the schematic sectional drawing which showed the cross section of the joint part of an exterior case.

Explanation of symbols

  10, 30, 40 ... exterior case, 11, 12, 13 ... exterior plate, 20 ... internal space, S1 ... passage

Claims (3)

An exterior case connected to a plurality of exterior plates to accommodate noise sources,
The main surfaces of the plurality of exterior plates are overlapped so as to face each other to form a passage portion that becomes a gap through which air flows, and the thickness of a part of the overlapped exterior plates is reduced in the middle of the passage portion. An exterior case characterized in that an internal space having a larger space than the gap is formed.   The said internal space forms a recessed part in both of the said laminated | stacked exterior boards, and is arrange | positioned and formed so that the opening part of both these recessed parts may mutually oppose. Exterior case.   The internal space is a groove formed along a direction perpendicular to the direction in which air flows from the inside to the outside. The groove has a substantially rectangular cross section and a groove width of about 4 mm. The exterior case according to claim 1 or 2, wherein

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