Electromagnetic wave shielding member and recording apparatus incorporating the same

[0001] The present invention relates to an electromagnetic wave shielding member installed so as to cover electronic components to shield an electromagnetic wave. The present invention also relates to a recording apparatus such as a facsimile machine and a printer, in which a circuit board constituting a control section is covered with such a shielding member.

[0002] Heretofore, in order to cut an electromagnetic wave irradiated from electronic components such as an IC, a LSI, and a transistor or an electromagnetic wave incident from the outside into the electronic components, it is performed that a circuit board is covered with an electromagnetic wave shielding member.

[0003] As one of the recording apparatus, there is a printer, which comprises a carriage including a recording head for performing printing on print paper, and provided so that it can reciprocate in a main scanning direction; a carriage guide shaft which guides the carriage in the main scanning direction; and a frame member which forms a plane parallel with the carriage guide shaft and forms a base body of the printer. In such the printer, a circuit board constituting a control section is arranged along a horizontal face located at the bottom of the apparatus, or arranged along the frame member. Therefore, it is important to reduce the space around the circuit board.

[0004] Therefore, in such a printer, it is not easy to cover the electronic components with the electromagnetic wave shielding member and further to install a heat release fin or a cooling fan with the electronic components in order to release heat generated from the electronic components to the outside. In result, there is a problem that free arrangement of the circuit board is difficult.

[0005] It is therefore an object of the invention to provide a heat releaser for electronic components which can reduce space around a circuit board.

[0006] In order to achieve the above object, according to the invention, there is provided an electromagnetic wave shielding member, which covers an electronic component, comprising a plate-shaped member having electric conductivity and thermal conductivity, formed with a contact portion which is brought into contact with the electronic component.

[0007] In such a configuration, since the electromagnetic wave shielding member releases heat generated from the electronic component through the contact part. Namely, the electromagnetic wave shielding member is used also as a heat releaser, whereby it is not necessary to provide a heat release fin or the like individually, the space for attaching the circuit board can be reduced, and free arrangement of the circuit board can be attained.

[0008] Preferably, a plurality of protrusions are formed on an exterior surface of the plate-shaped member.

[0009] In such a configuration, since surface area of the plate-shaped member is increased by the protrusions, heat release effect can be enhanced.

[0010] Preferably, the plate-shaped member is formed with a recessed portion such that an interior surface of the recessed portion serves as the contact portion.

[0011] In such a configuration, the electronic components can be brought into contact with the plate-shaped member while securing sufficient distance between the circuit board and the plate-shaped member. Further, since it is not necessary to individually provide a member having thermal conductivity between the electronic components and the plate-shaped member, cost can be reduced.

[0012] Preferably, the contact portion is located at a center portion of the plate-shaped member.

[0013] In such a configuration, heat generated from the electronic component can be released efficiently using the whole area of the plate-shaped member.

[0014] Preferably, the plate-shaped member is comprised of aluminum. In this case, weight reduction and of high heat release effect can be attained.

[0015] According to the invention, there is also provided a recording apparatus, comprising: a controller, including a circuit board on which an electronic component is mounted to control operations of the recording apparatus; and the above electromagnetic wave shielding member covering the electronic component.

[0016] Preferably, the recording apparatus further comprises: a carriage, on which a recording head operable to perform recording operation with respect to a recording medium is mounted; a guide shaft, extending in a first direction so as to form a reciprocating path of the carriage; and a frame member, extending in the first direction so as to form a base body of the recording apparatus. The controller is disposed on the frame member such that the circuit board extends in a second direction perpendicular to the first direction.

[0017] Preferably, both sides of the circuit board are covered with the electromagnetic wave shielding member.

[0018] In such a configuration, it is not necessary to take electromagnetic wave shielding performance of the frame member into consideration, so that free design of the frame member can be enhanced.

[0019] Here, it is preferable that the controller is disposed in the vicinity of an end of the reciprocating path of the carriage such that the controller is exposed to air flow generated by a reciprocating motion of the carriage.

[0020] Since the carriage has relatively large size in the recording apparatus, when such a carriage reciprocates in the first scanning direction, air flow occurs in the vicinity of the carriage. Particularly in the vicinity of the end of the reciprocating path of the carriage, which is a turn back point, the air flow is perturbed most.

[0021] Therefore, by the air flow occurring with the reciprocating motion of the carriage, the circuit board (electronic component) is cooled.

[0022] Namely, the carriage in the recording apparatus is used as a heat releaser for releasing heat generated from the circuit board (electronic component). Hereby, the heat releaser of the circuit board (electronic component) is constituted at a low cost by utilizing the present component, and a heat release effect can be further improved by supporting the present heat releaser (for example, heat release fin).

[0032] Preferred embodiments of the invention will be described below with reference to the accompanying drawings.

[0033] As shown in FIG. 1, an ink jet printer 100 (hereinafter, simply referred as “printer”) according to a first embodiment has a lower cover member 1 covering a lower half of a printer body. Further, on the lower cover member 1, an upper cover member (not shown) is put, the printer body is covered with these two cover members to constitute the exterior appearance of the printer 100.

[0034] A base body of the printer 100 is constituted by a main frame 5. The main frame 5 comprises a center frame 5a extending in a main scanning direction of printing and side frames 5b and 5c located on both sides of the center frame 5a so as to protrude to the front side of the apparatus and to become perpendicular to the plane which the center frame 5a forms. On the backside of the main frame 5, a sheet feeder 3 for supplying a print sheet is provided, and on the front side of the main frame 5, a recording section (described later) which performs printing on the print sheet is provided.

[0035] Between the side frames 5b and 5c, a carriage guide shaft 9 extending in the main scanning direction is laid. On the front side of the main frame 5, a box-shaped carriage 7 including an ink cartridge 8 and a recording head (not shown) is arranged. The guide shaft 9 extends so as to penetrate the carriage 7, whereby it is guided in the main scanning direction. Further, on the both sides of the center frame 5a, freely rotatable driven pulley 13 and a drive pulley 11 driven by a drive motor (not shown) are set, and an endless belt 15 is laid between the drive pulley 11 and the driven pulley 13. The carriage 7 is fixed to a part of the endless belt 11, whereby it reciprocates in the main scanning direction. While the carriage 7 is reciprocating in the main scanning direction, an ink droplet supplied from the ink cartridge 8 is ejected from the recording head (not shown), whereby printing is executed.

[0036] As shown in FIG. 1, a circuit board 19 which is a part of a control unit 16 of the printer 100 is arranged on the left side of the sheet feeder 3 (on the left side viewed from the front side of the printer 100), so as to extend perpendicularly to the center frame 5a.

[0037] As shown in FIGS. 2 and 3, the control unit 16 comprises the circuit board 19 and a box-shaped power supply unit 17 arranged at the lower portion of the sheet feeder 3 to supply power to the circuit board 19.

[0038] Electronic components such as an IC, a transistor, and a CPU are mounted on the circuit board 19, and electromagnetic wave shielding members 23 and 25 are provided on both surfaces of the circuit board 19 in order to shield an electromagnetic wave radiated from the electronic components or an electromagnetic wave incident into the electronic components from the outside. These two electromagnetic wave shielding members 23 and 25 cover the whole of the circuit board 19.

[0039] Specifically, the electromagnetic wave shielding members 23 and 25 are tightly fixed onto the circuit board 19 by a screw member (not shown). These two electromagnetic wave shielding members 23 and 25 are respectively formed of a thin plate-shaped member having electric conductivity, and aluminum is used in the shielding member in this embodiment. However, any may be used as long as it has performance shielding an electromagnetic wave (electromagnetic wave shielding function).

[0040] Here, in this embodiment, the electromagnetic wave shielding member 23 has a heat release function in addition to the electromagnetic wave shielding function. Namely, in the embodiment, since the electromagnetic wave shielding member 23 is formed of aluminum, it has high thermal conductivity. As shown in FIG. 4A, the electromagnetic wave shielding member 23 has a recessed part 23a, and if is fixed onto the circuit board 19 so that the recessed part 23a is brought into contact with the whole of the flat upper surface of the electronic components 21. The recessed part 23a is formed integrally with the electromagnetic wave shielding member 23 by deep drawing without forming any hole, whereby the recessed part 23a is formed at a low cost and without damaging the electromagnetic wave shielding function.

[0041] In such a configuration, heat generated from the electronic components 21 is released through the recessed part 23a. Namely, since the electromagnetic wave shielding member 23 is used also as a heat releaser that releases heat generated from the electronic components 21, it is not necessary to provide a heat release fin individually, whereby space for providing the circuit board 19 can be reduced and the free design can be performed.

[0042] Further, since the recessed part 23a formed in the electromagnetic wave shielding member 23 is brought into contact the electronic components 21, the recessed part 23a releases the heat generated from the electronic components 21 while providing the sufficient distance between the electromagnetic wave shielding member 23 and the circuit board 19, and without individually providing a member having thermal conductivity therebetween.

[0043] In the embodiment, as shown in FIGS. 2 and 4A, since the electronic components 21 are mounted in a position slightly shifted to a side from a center of the circuit board 19, the recessed part 23a is also provided in a position slightly shifted to a side from a center of the electromagnetic wave shielding member 23. However, as shown in FIG. 4B, the electronic components 21 may be mounted in the center of the circuit board 19, and the recessed part 23a may be accordingly provided in the center of the electromagnetic wave shielding member 23. In such a configuration, heat generated from the electronic components 21 can be released more efficiently.

[0044] FIG. 5A shows an electromagnetic wave shielding member according to a second embodiment of the invention. In this embodiment, protrusions 23b are formed on a surface of the electromagnetic wave shielding member 23. In such a configuration, a surface area of the electromagnetic wave shielding member 23 increases by the protrusions 23b, whereby heat release ability can be enhanced.

[0045] FIG. 5B shows an electromagnetic wave shielding member according to a third embodiment of the invention. In this embodiment, a setting position of the electronic components 21 in the circuit board 19 is raised such that the flat top surface of the electronic components 21 is brought into contact with the electromagnetic wave shielding member 23. By such the constitution, the electromagnetic wave shielding member 23 can be formed at a low cost, and the protrusions shown in FIG. 5A can be readily provided.

[0046] In these embodiments, though aluminum is used as a material of the electromagnetic wave shielding member 23, any material may be used as long as it has the electromagnetic wave shielding function and high thermal conductivity.

[0047] In the embodiment, the circuit board 19 is disposed so as to be perpendicular to the center frame 5a as described before. Therefore, compared with the constitution in which the circuit board 19 is disposed on the backside of the center frame 5a thereby to give the electromagnetic wave shielding function to the center frame 5a, the free design of the main frame 5 can be performed because it is not necessary to give the electromagnetic wave shielding function to the center frame 5a.

[0048] In the above embodiments, the electromagnetic wave shielding member 23 is cooled by a cooler, whereby the heat generated from the electronic components 21 is released more surely.

[0049] As shown in FIG. 6, the circuit board 19 is disposed in the backside of the main frame 5 so as to extend perpendicularly to the center frame 5a, and placed in the vicinity of the side frame 5c, that is, in the vicinity of an end in a reciprocating path of the carriage 7 provided on the front side of the main frame 5.

[0050] Here, the carriage 7 has the shape of a box so as to mount the ink cartridge thereon as described before referring to FIG. 1, and its size is relatively large. Therefore, when such the carriage 7 reciprocates in the main scanning direction, air flow occurs in the vicinity of the carriage 7. More particularly in the vicinity of the end in the reciprocating path of the carriage 7, which is a turn back point of the carriage 7, the air flow is perturbed most.

[0051] Since the circuit board 19 is arranged in such the place where the air flow is perturbed, air around the circuit board 19 is also perturbed by the reciprocating motion of the carriage 7. Therefore, the heat released from the electromagnetic wave shielding member 23 (FIG. 2) provided so as to cover the circuit board 19 does not stay thereat, so that the electromagnetic wave shielding member 23 is cooled. Accordingly, the heat release effect of the electronic components 21 (FIG. 2) by the electromagnetic wave shielding member 23 can be further enhanced.

[0052] In other words, since the carriage 7 is utilized as the cooler for releasing the heat generated from the electromagnetic wave shielding member 23 (electronic components 21), use of the present component provides the cooler of the electromagnetic wave shielding member 23 (electronic components 21) at a low cost.

[0053] More specifically, a window 5d is formed on the center frame 5a at a portion close to the side frame 5c (where the circuit board 19 is arranged). Therefore, when the carriage 7 moves to the circuit board 19 side, air flowing through the window 5d to the circuit board 19 occurs together with air flow from the upper portion of the center frame 5a to the circuit board 19 as shown by arrows in FIG. 6. Hereby, the electromagnetic wave shielding member 23 (electronic components 21) is cooled more efficiently.

[0054] Further, the printer 100 is provided with the lower cover member 1 and the upper cover member (not shown) as described the above. Therefore, when the carriage 7 moves to the circuit board 19 side, the air flow comes into collision with an inner side wall 1a of the lower cover member 1 and flows also to the backside of the apparatus, that is, to the circuit board 19 side. Therefore, the cooling effect of the electromagnetic wave shielding member 23 (electronic components 21) can be further enhanced.

[0055] In addition, in the lower cover member 1, through holes (not shown) are formed at portions located on both sides of the reciprocating path of the carriage 7 (positions shown by reference numerals 2a and 2b in FIG. 1), through which air exchange between the apparatus inside and the apparatus outside can be performed, whereby the cooling effect of the electromagnetic wave shielding member 23 (electronic component 21) can be further enhanced.

[0056] When the carriage 7 moves in the direction where it approaches the circuit board 19, air is taken in from the through hole distant from the circuit board 19 (the through hole provided in the position shown by the reference numeral 2a), and it is exhausted from the other through hole (the through hole provided in the position shown by the reference numeral 2b). On the contrary, when the carriage 7 moves in the direction where it separates from the circuit board 19, air is taken in from the through hole near the circuit board 19 (the through hole provided in the position shown by the reference numeral 2b), and it is exhausted from the other through hole (the through hole provided in the position shown by the reference numeral 2a).

[0057] Therefore, in consideration with airflow with movement of the carriage 7, the through holes are thus provided on the both sides of the reciprocating path of the carriage 7, whereby their through holes have two functions of an intake port and an exhaust port. Therefore, the cooling effect of the electromagnetic wave shielding member 23 (electronic components 21) can be further enhanced.

[0058] Furthermore, as shown in FIG. 6, the electromagnetic wave shielding member 23 having the function of the heat releaser for the electronic components 21 is arranged in a position opposed to a side wall 3a of the sheet feeder 3 and in a position where narrow space is formed between the side wall 3a and the shielding member 23. Therefore, speed of air flowing between the sidewall 3a and the electromagnetic wave shielding member 23 becomes large. Namely, the accelerated air flow further enhances the cooling effect of the electromagnetic wave shielding member 23 (electronic components 21).

[0059] FIG. 7 shows an ink jet printer according to a fourth embodiment. In this embodiment, the circuit board 19 is disposed adjacent to the side frame 5c, so that the cooling effect of the electromagnetic wave shielding member 23 (electronic components 21) with the reciprocating motion of the carriage 7 can be further enhanced. Therefore, the air flow with the reciprocating motion of the carriage 7 directly comes into collision with the electromagnetic wave shielding member 23, whereby the electromagnetic wave shielding member 23 (electronic components 21) can be cooled more effectively.

[0060] The carriage 7 reciprocates in the main scanning direction usually with the printing operation. However, in the printer 100 according to the embodiment, there is provided a temperature detector (heat sensor: not shown) which detects temperature inside the cover member. When the control section in the printer 100 detects that the temperature inside the cover member is over the fixed value, it reciprocates the carriage 7 regardless of presence of print data. Therefore, even in case that there is no print data, air exchange between the cover member inside and the cover member outside is promoted, whereby it is possible to prevent the temperature of the electromagnetic wave shielding member 23 (electronic components 21) from excessively rising.