Broadcasting reception device, covering plate, and manufacturing method for the broadcasting reception device

Abstract

To provide a broadcasting reception device that can prevent leakage of electromagnetic waves without obstructing heat dissipation.SOLUTION: The broadcasting reception device includes a printed wiring board on which a plurality of components is mounted. The plurality of components includes: a tuner; a metal electromagnetic shield frame surrounding the tuner; and a metal covering plate that covers the entire electromagnetic shield frame from a side opposite to a side on which the printed wiring board is located. The covering plate includes: a protruding part that is in direct or indirect contact with the tuner and is thermally joined to the same; and a grounding part that is conductive to the grounding potential wiring of the printed wiring board.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a broadcast receiving apparatus, a covering plate, and a method for manufacturing a broadcast receiving apparatus.

Background Art

[0002] In recent years, there has been a demand for miniaturization and thinning of electronic devices. On the other hand, in electronic devices, the surface temperature of electronic components such as CPUs built into the housing may become high due to heat generated by the electronic components, which may have an adverse effect on the reliability of the electronic components. In addition, electromagnetic waves generated by electronic devices may have an adverse effect on other electronic devices.

[0003] For example, Patent Document 1 describes an electronic device that cools a heat-generating component mounted on a substrate with a cooling fan. Patent Document 2 describes a tuner housed in a metal case.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, although the heat-generating components of the electronic device described in Patent Document 1 are cooled by a cooling fan, the leakage of electromagnetic waves is not considered, and there is a risk that the electromagnetic waves generated by the heat-generating components may have an adverse effect on other electronic devices. On the other hand, the tuner described in Patent Document 2 is covered by a metal case, and the leakage of electromagnetic waves is considered, but the heat generated by the tuner is not considered. In an electronic device that handles high-frequency signals and generates a large amount of heat, in order to prevent the leakage of electromagnetic waves, it is covered with a metal case, but there is a risk that heat dissipation may be hindered by being covered with the metal case.

[0006] In view of such conventional problems, an object of the present disclosure is to provide an electronic device that can prevent electromagnetic wave leakage and does not prevent heat dissipation even in an electronic device that is required to be miniaturized and thinned.

Means for Solving the Problems

[0007] A broadcast receiving device according to an aspect of the present disclosure is a broadcast receiving device including a printed wiring board on which a plurality of components are mounted, wherein the plurality of components include a tuner, a metal electromagnetic shield frame surrounding the tuner, and a metal covering plate covering the entire area of the electromagnetic shield frame from the side opposite to the side where the printed wiring board exists, and the covering plate includes a convex portion that directly or indirectly contacts the tuner and is thermally coupled to the tuner, and a grounding portion that is electrically connected to the grounding potential wiring of the printed wiring board.

Effects of the Invention

[0008] According to the present disclosure, it is possible to provide a broadcast receiving device that can prevent radio wave leakage and does not prevent heat dissipation.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0010] <Summary of Embodiments of the Present Disclosure> Hereinafter, the summary of the embodiments of the present disclosure will be listed and described. (1) The broadcast receiving apparatus of the present embodiment is a broadcast receiving apparatus including a printed wiring board on which a plurality of components are mounted, and the plurality of components include a tuner, a metal electromagnetic shield frame surrounding the tuner, and a metal covering plate covering the entire area of the electromagnetic shield frame from the side opposite to the side where the printed wiring board is located. The covering plate includes a convex portion that directly or indirectly contacts the tuner and is thermally coupled to the tuner, and a grounding portion that is electrically connected to the grounding potential wiring of the printed wiring board. According to the broadcast receiving apparatus of the present embodiment, since the covering plate contacts the tuner and the covering plate and the electromagnetic shield frame cover the tuner, while dissipating the heat of the tuner, the electromagnetic waves from the tuner are shielded. Therefore, it is possible to provide a broadcast receiving apparatus that can prevent electromagnetic wave leakage while not preventing heat dissipation.

[0011] (2) In the broadcast receiving apparatus described in (1) above, the shape formed by the electromagnetic shield frame and the covering plate may be a shape capable of covering the tuner so as not to be visible from the outside. Since the shape formed by the electromagnetic shield frame and the covering plate makes the outside world invisible when viewed from the tuner through having such a shape, the electromagnetic waves radiated by the tuner do not leak to the outside world. Therefore, it is possible to provide a broadcast receiving apparatus that further prevents electromagnetic wave leakage and does not prevent heat dissipation.

[0012] (3) In the broadcast receiving apparatus according to any one of (1) or (2) above, the surface of the covering plate on the side opposite to the side where the tuner is located faces the back surface of the housing of the broadcast receiving apparatus in a state of being parallel and spaced apart by a predetermined distance, and the predetermined distance may be smaller than the height of the convex portion. Since the distance between the covering plate and the housing becomes shorter by taking such a distance, the thermal resistance between the covering plate and the housing decreases. Therefore, it is possible to provide a broadcast receiving apparatus that further prevents electromagnetic wave leakage and does not prevent heat dissipation.

[0013] (4) In the broadcast receiving apparatus according to any one of (1) to (3) above, the grounding portion includes a support nut for screwing the covering plate to the printed wiring board, and the end surface of the support nut may be pressurized and electrically connected to the wiring by screwing. By taking such a form, since the contact pressure increases between the end surface of the support nut and the connection portion and they are in electrical contact, the electrical resistance decreases. Therefore, it is possible to reduce the electrical resistance between the covering plate and the wiring of the ground potential of the printed wiring board.

[0014] (5) The covering plate of the present embodiment is a covering plate of a tuner mounted on a printed wiring board, and includes a metal plate body having a size capable of including the electromagnetic shield frame for the tuner within the plate surface, a convex portion for thermal bonding formed on the plate body, and a grounding portion for wiring the plate body to the ground potential. According to the covering plate of the present embodiment, while the covering plate is in contact with the tuner, it covers the tuner and the electromagnetic shielding frame, so that it can dissipate the heat of the tuner and shield the electromagnetic waves from the tuner. Therefore, it is possible to provide a covering plate that can prevent the leakage of electromagnetic waves from the tuner while not hindering heat dissipation.

[0015] (6) The manufacturing method of the broadcast receiving apparatus of the present embodiment is a manufacturing method of a broadcast receiving apparatus equipped with a printed wiring board, including: a first step of attaching a tuner to the printed wiring board; a second step of attaching an electromagnetic shielding frame surrounding the periphery of the tuner to the printed wiring board; a third step of attaching a metal covering plate that covers the entire area of the electromagnetic shielding frame from the side opposite to the side where the printed wiring board exists to the printed wiring board; and a fourth step of attaching the printed wiring board to which the tuner, the electromagnetic shielding frame, and the covering plate are attached to the housing of the broadcast receiving apparatus. In the third step, the covering plate is thermally coupled to the tuner and electrically connected to the ground potential of the printed wiring board. According to the manufacturing method of the broadcast receiving apparatus of the present embodiment, since the covering plate attached to the printed wiring board mounted on the broadcast receiving apparatus is in contact with the tuner and the covering plate and the electromagnetic shielding frame cover the tuner, the broadcast receiving apparatus can dissipate the heat of the tuner while shielding the electromagnetic waves from the tuner. Therefore, it is possible to manufacture a broadcast receiving apparatus that can prevent the leakage of electromagnetic waves while not hindering heat dissipation.

[0016] [Definition of Terms] The definitions of the terms used in the present application are as follows. · Set-top box: A terminal device connected to a television to enable viewing of movie content etc. distributed through a broadband IP (internet protocol) network on the television screen. · Thermal resistance: The resistance to the transfer of heat, which is the value obtained by dividing the temperature difference between any two points by the heat flow rate (the amount of heat flowing per unit time) flowing between the two points.

[0017] <Details of Embodiments of the Present Disclosure> Hereinafter, with reference to the drawings, the details of the embodiments of the present disclosure will be described. Here, the details of the embodiments of the present disclosure will be described by taking a set-top box as an example, which is an example of the embodiments of the present disclosure.

[0018] 〔1. Overall Configuration of Broadcast Receiver According to the Present Disclosure〕 FIG. 1 is a perspective view of a set-top box according to an embodiment of the present disclosure as viewed from the front side. FIG. 2 is an exploded perspective view of FIG. 1, and FIG. 3 is an exploded perspective view of the set-top box shown in FIG. 1 excluding the housing. FIG. 4 is a perspective view of the tuner excluding the covering plate from FIG. 3. FIG. 5 is a cross-sectional view taken along line A-A of FIG. 2 (description of the cross-section of the tuner 31 is omitted).

[0019] As shown in FIGS. 1 and 2, the set-top box 1 includes a housing 21 and a printed wiring board 22 housed in the housing 21.

[0020] 〔2. Each Component of Broadcast Receiver According to the Present Disclosure〕 <Housing> The housing 21 is made of resin and is configured to be separable into an upper housing 21a and a lower housing 21b. The upper housing 21a has a notch for passing a plug for connecting a coaxial cable and an opening for passing a USB (Universal Serial Bus) cable or the like, and a member for pressing a plurality of switches provided on the printed wiring board 22 is provided. The lower housing 21b is provided with screw holes for screwing the printed wiring board 22 and the upper housing 21a, and the printed wiring board 22 and the upper housing 21a are fixed by screws 35. Thereby, the set-top box 1 can be assembled.

[0021] <Printed Wiring Board> The printed wiring board 22 has a rectangular shape in plan view as shown in FIG. 2, and the length in the depth direction thereof (the length from the side wall 23a to the side wall 23c of the housing 21) is slightly shorter than the distance between the side wall 23a and the side wall 23c. Also, the length of the printed wiring board 22 in the width direction (the length in the direction from the side wall 23b to the side wall 23d of the housing) is slightly shorter than the distance between the side wall 23b and the side wall 23d.

[0022] As shown in FIG. 3, a plurality of components are mounted on the printed wiring board 22. The plurality of components include a tuner 31, an electromagnetic shield frame 32, and a covering plate 33. In addition to these, the printed wiring board 22 is provided with an LSI (Large Scale Integration) for performing the function of a set-top box, a switch for operating the function of the set-top box, a USB connector for inserting a USB cable, and the like.

[0023] The printed wiring board 22 is a board including conductor wirings on or inside a substrate of an insulator, for example, a substrate impregnated with an epoxy resin in glass fiber. The conductor wiring is, for example, a copper alloy. Each terminal of an electronic component such as an LSI is soldered to the wiring, whereby the electronic component is mounted on the printed wiring board 22. The wiring of the printed wiring board connects the terminals of the electronic components to each other, and at the same time, the printed wiring board functions as a support member for supporting the electronic components.

[0024] <Tuner> The tuner 31 has, for example, a rectangular parallelepiped shape and is mounted on the printed wiring board 22. The coaxial cable is connected to the tuner 31. For example, broadcast radio waves received by an antenna or signals of cable television are carried to the tuner 31 via the coaxial cable and received by the tuner 31. The broadcast radio waves or the signals of cable television include signals of a plurality of TV programs. The tuner 31 extracts a signal corresponding to a predetermined TV program from the signals including a plurality of TV programs.

[0025] The tuner 31 includes semiconductor components, coils, capacitors, and resistors for extracting signals. The semiconductor components are, for example, ICs (Integrated Circuits) or FETs (Field Effective Transistors), which consume power for the operation of extracting signals and generate heat due to the consumed power. Other than semiconductor components, the temperature range in which they can operate is determined, and they need to operate within this temperature range. If the heat generated by the semiconductor components cannot be sufficiently dissipated outside the set-top box, the temperature of the semiconductor components will rise, and there is a risk of exceeding the operable temperature range. Therefore, the set-top box 1 is configured so that the electronic components do not exceed the operable temperature range.

[0026] Also, the tuner 31 operates at a high frequency, for example, 100 MHz or higher, to extract a signal corresponding to a predetermined TV program from a signal including a plurality of TV programs. Along with this, electromagnetic waves are radiated from the tuner 31. If the radiated electromagnetic waves reach other electronic devices, there is a risk of adversely affecting the operation of those electronic devices. Conversely, if electromagnetic waves radiated from other electronic devices reach the tuner 31, there is a risk of adversely affecting the operation of the tuner 31. For example, since the signal received by the tuner 31 is weak, if electromagnetic waves reach from other sources, there is a risk of adverse effects such as being unable to extract the signal corresponding to the predetermined TV program. For this reason, it is desirable that electronic devices do not affect and are not affected by the electromagnetic waves generated by each other. The performance of not affecting and not being affected by the electromagnetic waves generated by each other among electronic devices is called EMC (Electromagnetic Compatibility), and in JIS (Japanese Industrial Standards), it is defined as electromagnetic compatibility.

[0027] In order to prevent electronic devices from being affected by the electromagnetic waves generated by each other and from affecting each other, electronic devices are covered with a conductor connected to a fixed potential. The conductor connected to the fixed potential that covers the electronic device is also called an electromagnetic shield. As a result, electromagnetic waves reaching from the outside cannot penetrate into the inside of the electromagnetic shield and do not have an adverse effect on the internal electronic devices. Conversely, the electromagnetic waves generated by the internal electronic devices do not go out of the electromagnetic shield and do not have an adverse effect on other electronic devices. The electromagnetic shield is composed of, for example, a metal plate. From the viewpoints of easy connection and no risk of electric shock, the ground potential is usually selected as the fixed potential.

[0028] However, when an electronic device is covered with an electromagnetic shield, it becomes difficult to dissipate the heat generated by the electronic device inside the electromagnetic shield to the outside.

[0029] <Electromagnetic shield frame> The electromagnetic shield frame 32 is a metal electromagnetic shield that surrounds the tuner 31. The electromagnetic shield frame 32 is composed of, for example, a thin metal plate and has a shape that is slightly larger, for example, 1 mm larger than the width in the short direction, the depth in the long direction, and the height in the vertical direction of the tuner 31. The electromagnetic shield frame 32 has an opening 32b on the side opposite to the side where the printed wiring board 22 exists (hereinafter referred to as the "coating plate side") for the convex portion of the coating plate described later to contact the tuner, and has an opening for mounting the tuner 31 to the printed wiring board 22 on the side where the printed wiring board 22 exists. The electromagnetic shield frame 32 may include an adsorption pad 32a for surface mounting.

[0030] For example, when the electromagnetic shield frame 32 is soldered to the ground potential wiring of the printed wiring board 22, the electromagnetic shield frame 32 is electrically connected to the ground potential wiring of the printed wiring board 22. The electromagnetic shield frame 32 functions as an electromagnetic shield that blocks electromagnetic waves by being electrically connected to the ground potential, which is a fixed potential.

[0031] The electromagnetic shielding frame 32 is placed on the printed wiring board 22 by a mounter used for, for example, surface mounting technology. After assembling the tuner 31 and the electromagnetic shielding frame 32 together, this assembly may be placed on the printed wiring board 22. Thereafter, as the printed wiring board 22 passes through a solder reflow oven, the surface-mounted components placed on the printed wiring board 22 are soldered and fixed to the printed wiring board 22.

[0032] <Cover plate> The cover plate 33 is a metal sheet that covers the entire area of the electromagnetic shielding frame 32 from the cover plate side. The cover plate 33 includes a plate body 33a, a convex portion 33b, and a grounding portion 33c. The plate body 33a is a sheet metal having a size capable of enclosing the electromagnetic shielding frame 32 for the tuner 31 within the plate surface. For example, the shape in plan view is a rectangular shape. The convex portion 33b is a portion for thermal bonding formed on the plate body 33a, which contacts the tuner 31 directly or indirectly and is provided at a predetermined position of the plate body 33a. The detailed position will be described later. The grounding portion 33c is a portion for wiring the plate body 33a to the ground potential, and is electrically connected to the wiring of the ground potential of the printed wiring board 22. Since the cover plate 33 functions as a heat sink, a material with high thermal conductivity is selected as its material, for example, aluminum. When the cover plate 33 is made of aluminum, the surface of the cover plate 33 may be anodized. Thereby, the amount of heat radiation by radiation can be improved. Also, the anodizing treatment may be further colored black. Further, the amount of heat radiation by radiation can be improved.

[0033] The covering plate 33 is fixed to the lower housing 21b by screws 35 together with, for example, the printed wiring board 22. Specifically, the screw 35 is screwed into the support nut 36 provided on the covering plate 33 through the holes provided in the lower housing 21b and the holes provided in the printed wiring board 22 from the back side of the lower housing 21b. The support nut 36 is a nut for screwing the covering plate 33 to the printed wiring board 22 and also functions to support the covering plate 33. The support nut 36 is, for example, a member having a hollow cylindrical shape made of metal and is fixed to the covering plate 33 by being press-fitted into the hole opened in the covering plate 33. When the screw 35 is screwed into the support nut 36, the support nut 36 fixes the covering plate 33 and the printed wiring board 22 to the lower housing 21b. At the same time, the support nut 36 supports the covering plate 33 on the printed wiring board 22. Further, when the covering plate 33 is fixed to the lower housing 21b, the convex portion 33b of the covering plate 33 contacts the upper surface 31a of the tuner 31 directly or indirectly through the opening 32b of the electromagnetic shield frame 32 and is thermally coupled to the tuner 31. At the same time, the covering plate 33 is electrically connected to the ground potential of the printed wiring board 22. The electrical connection will be described later.

[0034] The covering plate 33 has a shape that covers the entire area of the electromagnetic shield frame 32 from the covering plate side. As a result, the opening on the covering plate side of the electromagnetic shield frame 32, including the opening 32b, is covered by the covering plate 33. Thereby, the electromagnetic waves radiated through the opening are shielded. Also, from the viewpoint of heat dissipation, the size of the covering plate 33 when viewed in plan view only needs to be larger than a size that can keep the temperature of the tuner 31 below the upper limit of the operable temperature range. However, as the area where the covering plate 33 and the back surface of the upper housing 21a face each other increases, the thermal resistance between the covering plate 33 and the upper housing 21a decreases. The covering plate 33 may further be provided with a side wall 33d extending toward the printed wiring board 22. The side wall 33d resists the force to bend the covering plate 33 and supports the covering plate 33 when it contacts the printed wiring board 22.

[0035] The covering plate 33 is provided with a convex portion 33b, for example, by pressing. The position of the convex portion 33b on the covering plate 33 is a position corresponding to the position of the opening 32b of the electromagnetic shielding frame 32 when the covering plate 33 is mounted on the printed wiring board 22. As shown in FIG. 3, the shape of the convex portion 33b when the covering plate 33 is viewed in plan is a shape following the opening 32b of the electromagnetic shielding frame 32, and is, for example, a rectangular shape.

[0036] As shown in FIG. 5, the cross-sectional shape of the convex portion 33b when the covering plate 33 is viewed from the A-A line cross-section is, for example, a dish shape. The convex portion 33b may have a shape that inclines from the contact portion 33f in contact with the tuner 31 of the convex portion 33b toward the covering plate 33. The said shape may be determined based on the ease of processing in the case of pressing the covering plate 33.

[0037] The height H of the convex portion 33b, which is the distance between the lower surface of the covering plate 33 and the contact portion 33f of the convex portion 33b, only needs to be at least higher than the upper end 32d of the side wall 32c of the electromagnetic shielding frame 32 from the upper surface 31a of the tuner 31. Thereby, the covering plate 33 can contact the upper surface 31a of the tuner 31 without being obstructed by the upper end 32d of the side wall 32c of the electromagnetic shielding frame 32. Further, the height H of the convex portion 33b is shorter than the distance from the upper surface 31a of the tuner 31 to the back surface of the upper housing 21a. Thereby, the upper surface 33e and the back surface of the upper housing 21a are separated, and the possibility that the upper surface 33e and the back surface of the upper housing 21a come into contact and the covering plate 33 or the housing 21 is damaged is reduced.

[0038] As shown in FIGS. 3 and 5, the upper surface 31a of the tuner 31 and the contact portion 33f of the covering plate 33 are in contact via a heat conduction member 34. The heat conduction member 34 is, for example, a heat conduction sheet, but is not limited thereto, and may be a heat conduction paste. The heat generated by the tuner 31 is transmitted to the covering plate 33 via the heat conduction member 34 and dissipated from the covering plate 33. Due to the presence of the heat conduction member 34, the thermal resistance between the covering plate 33 and the tuner 31 is reduced.

[0039] FIG. 6 is an enlarged view showing an enlarged area of the dashed-dotted line B in FIG. 2. FIG. 6 shows a portion where the covering plate 33 is electrically connected to the ground potential wiring of the printed wiring board 22, that is, the grounding portion 33c. Specifically, the grounding portion 33c of the covering plate 33 is connected to the connection portion 61 of the ground potential wiring of the printed wiring board 22 via the support nut 36. The support nut 36 is press-fitted into a hole formed in the covering plate 33 after anodizing. Since the anodizing is removed by forming the hole, the support nut 36 and the covering plate 33 are in direct electrical contact. As a result, the electrical resistance between the support nut 36 and the covering plate 33 is reduced as compared with the case where there is anodizing.

[0040] Also, in the printed wiring board 22, the resist 62 is removed from the connection portion 61 where the support nut 36 contacts. The resist 62 is a film of a polymer polymer for protecting the surface of the printed wiring board 22 and has a high electrical resistance. The connection portion 61 where the support nut 36 contacts is the ground potential wiring of the printed wiring board 22. The ground potential wiring is composed of, for example, a copper foil. Then, the printed wiring board 22 and the lower housing 21b are screwed together by the screw 35 and the support nut 36. As a result, the end face of the support nut 36 is pressed against the connection portion 61 and conducts, so that the contact pressure between the end face of the support nut 36 and the connection portion 61 increases, and the electrical resistance between the covering plate 33 and the ground potential wiring of the printed wiring board 22 is reduced.

[0041] FIG. 7 is an enlarged view of the range of the dashed-dotted line C in FIG. 2. FIG. 7 shows a USB connector 72 provided on the printed wiring board 22, a gasket 71, and a covering plate 33. Also in this portion, the covering plate 33 is electrically connected to the wiring of the ground potential of the printed wiring board 22. Specifically, the covering plate 33 is connected to the wiring of the ground potential of the printed wiring board 22 via the gasket 71 and the metal outer frame of the USB connector 72. The gasket 71 is, for example, a sponge whose outer skin is covered with a metal foil. The gasket 71 is inserted between the covering plate 33 and the metal outer frame of the USB connector 72. The alumite is removed from the back side of the covering plate 33 that the gasket 71 contacts. Thereby, the outer skin of the metal foil of the covering plate 33 and the gasket 71 are in direct electrical contact. Also, the outer skin of the metal foil of the gasket 71 and the metal outer frame of the USB connector 2 are in contact and electrically connected.

[0042] Also, the USB connector is placed on the printed wiring board 22 by, for example, a mounter for surface mounting, and is soldered by passing the printed wiring board 22 through a reflow oven. Thereby, the metal outer frame of the USB connector is in direct electrical contact with the wiring of the ground potential of the printed wiring board 22. As described above, the covering plate 33 is connected to the wiring of the ground potential of the printed wiring board 22 via the outer skin of the metal foil of the gasket 71 and the metal outer frame of the USB connector 72.

[0043] Also, when the covering plate 33 is fixed to the lower housing 21b together with the printed wiring board 22 by screws 35, the convex portion 33b of the covering plate 33 is fitted into the opening 32b of the electromagnetic shield frame 32. And the covering plate 33 having a size capable of including the electromagnetic shield frame 32 for the tuner 31 within the plate surface covers the electromagnetic shield frame 32. In other words, the opening on the covering plate side of the electromagnetic shield frame 32, including the opening 32b, is covered with the covering plate 33. As a result, when looking at the tuner 31 from the outside, there is no gap in the silhouette formed by the electromagnetic shield frame 32 and the covering plate 33, and the electromagnetic waves radiated by the tuner 31 can be shielded without leakage.

[0044] Returning to FIG. 5, the positional relationship between the covering plate 33 and the upper housing 21a will be described. The surface of the covering plate 33 on the side opposite to the side where the tuner 31 is located, in other words, the upper surface 33e of the covering plate 33, faces the back surface of the housing 21 of the set-top box 1 in a state of being parallel and spaced apart by a predetermined distance, and the predetermined distance is smaller than the height of the convex portion 33b.

[0045] The distance from the back surface of the housing 21 to the upper surface 33e of the covering plate 33 will be described. Here, let the distance from the back surface of the housing 21 to the upper surface 33e of the covering plate 33 be the gap δ. The gap δ is greater than 0 in order to prevent the housing 21 and the covering plate 33 from coming into contact as described above. Also, as the gap δ increases, the thermal resistance between the covering plate 33 and the upper housing 21a increases, so the gap δ is equal to or less than the height H of the convex portion 33b. Expressing this as an equation gives Equation 1. 0 < δ ≤ H......(1) Also, if the thickness of the member of the housing 21 is T, the gap δ may be within the range of Equation 2. 0 < δ ≤ T......(2) More specifically, the gap δ may be within the range of Equation 3. 0.2 mm ≤ δ ≤ 0.3 mm......(3) As described above, since the distance between the covering plate 33 and the upper housing 21a is shortened, the thermal resistance between the covering plate 33 and the upper housing 21a decreases.

[0046] Note that the upper surface 33e and the back surface of the upper housing 21a face each other in a state of being parallel and spaced apart by a predetermined distance, but they may be deviated from parallel to an extent caused by manufacturing variations in the set-top box 1, the housing 21, the covering plate 33, etc.

[0047] 〔3. Functions of the broadcast receiving apparatus according to the present disclosure〕 <Regarding heat dissipation> As described above, when the tuner 31 operates, the tuner 31 generates heat. Due to this heat, the temperature of the tuner 31 rises. However, in order to keep the temperature below the upper limit of the operable temperature of the tuner 31, it is necessary to dissipate the generated heat outside the set-top box 1.

[0048] The heat generated by the tuner 31 is transmitted to the covering plate 33 via the heat conduction member 34. The heat transmitted to the covering plate 33 is transmitted to the housing 21 by the following three mechanisms.

[0049] The first is radiation. The heat transmitted to the covering plate 33 is radiated from the covering plate 33 as infrared rays corresponding to the temperature. The radiated infrared rays reach the back surface of the housing 21. The housing 21 absorbs the reached infrared rays, and the temperature of the housing 21 rises.

[0050] The second is heat conduction. The heat transmitted to the covering plate 33 raises the temperature of the air around the covering plate 33. Then, the air with the increased temperature raises the temperature of the housing 21.

[0051] The third is convection. The heat transmitted to the covering plate 33 raises the temperature of the air around the covering plate 33. Then, the air with the increased temperature flows upward in the state where the set-top box 1 is placed, and raises the temperature of the housing 21 at the destination of the flow.

[0052] Then, the housing 21 with the increased temperature is radiated outward from the surface of the housing 21 as infrared rays corresponding to the temperature. Also, the heat transmitted to the housing raises the temperature of the air around the set-top box 1 and dissipates heat by convection. By these mechanisms, the heat generated by the tuner 31 can be dissipated outside the set-top box 1.

[0053] <Regarding electromagnetic shielding> As described above, when the tuner 31 operates, the tuner 31 radiates electromagnetic waves. The wiring included in the tuner 31 functions as an antenna that radiates electromagnetic waves. Since the wiring included in the tuner 31 faces in various directions, the electromagnetic waves radiated by the tuner 31 are radiated omnidirectionally from the tuner 31.

[0054] On the other hand, when there is a conductor connected to a fixed potential such as a ground potential in front of the radiated electromagnetic waves, the electromagnetic waves cannot proceed further. Since the electromagnetic shield frame 32 and the covering plate 33 are electrically connected to the wiring of the ground potential of the printed wiring board 22, the electromagnetic waves radiated in the direction of the electromagnetic shield frame 32 and the covering plate 33 cannot proceed further, and the electromagnetic shield frame 32 and the covering plate 33 can shield the electromagnetic waves radiated by the tuner 31.

[0055] Specifically, the shape formed by the electromagnetic shield frame 32 and the covering plate 33 is a shape that can cover the tuner so as not to be visible from the outside. As a result, when looking at the tuner 31 from the outside, the outside cannot be seen, and the electromagnetic waves radiated by the tuner 31 do not leak to the outside. More specifically, the convex portion 33b of the covering plate 33 is fitted into the opening 32b of the electromagnetic shield frame 32. And the covering plate 33 having a size capable of including the electromagnetic shield frame 32 for the tuner 31 within the plate surface covers the opening on the covering plate side of the electromagnetic shield frame 32. As a result, there is no gap in the silhouette formed by the electromagnetic shield frame 32 and the covering plate 33 as seen from the tuner 31, and the electromagnetic waves radiated by the tuner 31 are shielded without leakage.

[0056] Note that the wiring board included in the tuner 31 and the printed wiring board 22 are usually multilayer substrates, and in one of the layers, a conductor connected to the ground potential spreads over the entire surface of the wiring board. In this case, the back side of the tuner 31 is shielded by the conductor. Therefore, the shape formed by the electromagnetic shield frame 32 and the covering plate 33 as seen from the tuner 31 does not have to reach the back side of the tuner 31.

[0057] [4. Summary] As described above, the set-top box 1 of the present disclosure can dissipate the heat generated by the tuner 31 to the outside while preventing the leakage of the electromagnetic waves radiated by the tuner 31 to the outside. Further, since a fan for heat dissipation is not used, it is possible to suppress the unpleasant noise caused by the fan and the motor for driving the fan. Furthermore, since there is no fan, it is possible to reduce the risk of dust being sucked in and dust clogging, thereby inhibiting heat dissipation. In addition, since there is no motor for driving the fan, the probability of failure can be reduced.

[0058] The embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the rights of the present invention is not limited to the above-described embodiments, but includes all modifications within the scope equivalent to the configurations described in the claims.

Explanation of Reference Numerals

[0059] 1 Set-top box 21 Housing 21a Upper housing 21b Lower housing 22 Printed wiring board 23a, 23b, 23c, 23d Side walls 31 Tuner 31a Upper surface 32 Electromagnetic shield frame 32a Adsorption pad 32b Opening 32c Side wall 32d Upper end 33 Cover plate 33a Plate body 33b Convex portion 33c Grounding portion 33d Side wall 33e Upper surface 33f Contact portion 34 Heat conduction member 35 Screw 36 Support nut 61 Connection portion 62 Resist 71 Gasket 72 USB connector Height of the H protrusion Thickness of the member of the housing Gap δ

Claims

1. A broadcast receiving apparatus comprising a printed wiring board on which a plurality of components are mounted, wherein the plurality of components include: a tuner, a metal electromagnetic shield frame surrounding the tuner, and a metal covering plate covering the entire area of the electromagnetic shield frame from the side opposite to the side where the printed wiring board is located, wherein the covering plate includes: a convex portion that directly or indirectly contacts the tuner and is thermally coupled to the tuner, and a grounding portion that is electrically connected to the grounding potential wiring of the printed wiring board.

2. The shape formed by the electromagnetic shield frame and the covering plate is a shape capable of covering the tuner so as not to be visible from the outside, The broadcast receiving apparatus according to claim 1.

3. The surface of the covering plate on the side opposite to the side where the tuner is located faces the back surface of the housing of the broadcast receiving apparatus in a state of being parallel and spaced apart by a predetermined distance, and the predetermined distance is smaller than the height of the convex portion, The broadcast receiving apparatus according to claim 1 or claim 2.

4. The grounding portion includes a pillar nut for screwing the covering plate to the printed wiring board, and the end face of the pillar nut is pressed against the wiring by screwing to establish electrical connection, The broadcast receiving apparatus according to claim 1 or claim 2.

5. A covering plate for a tuner mounted on a printed wiring board, comprising a metal plate body having a size capable of including the electromagnetic shield frame for the tuner within the plate surface,

5. A covering plate for a tuner mounted on a printed wiring board, comprising a metal plate body having a size capable of including the electromagnetic shield frame for the tuner within the plate surface, and a convex portion that directly or indirectly contacts the tuner and is thermally coupled to the tuner, The convex portion for thermal bonding formed on the plate body, and A grounding portion for wiring the plate body to a ground potential, and a coated plate including the same.

6. A method for manufacturing a broadcast receiving apparatus on which a printed wiring board is mounted, comprising: A first step of attaching a tuner to the printed wiring board; A second step of attaching an electromagnetic shield frame surrounding the periphery of the tuner to the printed wiring board; A third step of attaching a metal coated plate that covers the entire area of the electromagnetic shield frame from the side opposite to the side where the printed wiring board is located to the printed wiring board; A fourth step of attaching the printed wiring board to which the tuner, the electromagnetic shield frame, and the coated plate are attached to the housing of the broadcast receiving apparatus, the method for manufacturing a broadcast receiving apparatus, wherein In the third step, The coated plate is thermally bonded to the tuner and electrically connected to the ground potential of the printed wiring board.

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