Patent Application
20110075375
This application is based upon and claims the benefit to priority from Japanese patent application No. 2009-223791, filed on Sep. 29, 2009, the disclosure of which is incorporated herein in its entirety by reference.
This invention relates to a tuner module for a radio receiver and, in particular, relates to a tuner module suitable for an automobile digital radio receiver capable of listening to digital radio broadcasting by receiving radio waves from an artificial satellite (hereinafter referred to as “satellite waves”) or radio waves on the ground (hereinafter referred to as “terrestrial waves”).
SDARS (Satellite Digital Audio Radio Service) is a radio service according to a digital radio broadcasting using artificial satellites (which will called “SDARS satellites” hereinafter) in the United States of America. That is, in recent years, a digital radio receiver, which receives the satellite wave from the SDARS satellites or the terrestrial wave so as to listen to the digital radio broadcasting, has been developed and is put to practical use in the United States of America. Specifically, two broadcasting stations called XM and Sirius provide radio programs on 250 or more channels in total. The digital radio receiver is generally mounted on a mobile object (a mobile station) such as an automobile and is adapted to receive a radio wave (a SDARS signal) having a frequency of about 2.3 gigahertz (GHz) as a received wave to listen to the digital radio broadcasting. In other words, the digital radio receiver is a radio receiver capable of listening to mobile broadcasting. Inasmuch as the received wave (the SDARS signal) has the frequency of about 2.3 GHz, a reception wavelength (resonance frequency) λ thereof is equal to about 128 mm. It is noted here that the terrestrial wave is a radio wave obtained by receiving the satellite wave at a ground station, slightly shifting the frequency of the satellite wave, and retransmitting the linear polarized wave. Thus, the terrestrial wave is the linear polarized wave exhibiting linear polarization while the satellite wave is a circular polarized wave exhibiting circular polarization. As an antenna for SDARS, a planer antenna such as a patch antennas is used.
An XM satellite radio antenna apparatus normally serves to receive circular polarized radio waves from two stationary satellites and, in an insensitive zone of the circular polarized waves, receives a radio wave by using a terrestrial linear polarization portion of the radio antenna apparatus. On the other hand, a Sirius satellite radio antenna apparatus normally serves to receive circular polarized radio waves from three orbiting satellites (synchronous type) and, in the insensitive zone, receives a radio wave by a terrestrial linear polarization portion of the radio antenna apparatus.
As described above, the radio wave (the SDARS signal) having the frequency of about 2.3 GHz is used in the digital radio broadcasting. Therefore, an antenna for receiving the SDARS signal may be almost located outside as known in the art. If the digital radio receiver is mounted in the mobile object (the mobile station) such as the automobile, the antenna unit may be almost attached to a roof of the mobile object (the mobile station).
Such as an antenna for the automobile and a receiver body (a head unit) put inside a room of the automobile are electrically connected to each other through an extension cable. The head unit serves as an external device.
A receiving system of the type described for receiving the satellite wave or the terrestrial wave includes an antenna portion (an antenna unit) and a tuner portion (a satellite digital radio reception module). The antenna portion (the antenna unit) receives the satellite wave or the terrestrial wave to produce a reception signal having a high frequency. The turner portion (the satellite digital radio reception module) demodulates the reception signal into a speech signal.
Normally, electronic components constituting the tuner are mounted on a printed wiring board and placed in a metal case also serving as a shield (see, e.g. Japanese Unexamined Patent Application Publication (JP-A) No, H06-209268).
Referring to
In the meantime, the electronic components constituting the tuner include IC components from which heat generates. In order to favorably radiate heat generated from the IC components to outside, a tuner module in which a heat conductive sheet (a heat transfer sheet) is provided between an electronic component (the IC component) and a metal case is suggested (see, e.g. U.S. Pat. No. 7,778,044). The heat conductive sheet (the heat transfer sheet) is, for example, made of silicone rubber having high thermal conductivity.
On the other hand, in order to confirm the presence or absence of the heat conductive sheet (the heat transfer sheet) or to inhibit to forget about sticking up the heat conductive sheet (the heat transfer sheet), boring of a sight hole in the metal case has been carried out. For example, Japanese Unexamined Patent Application Publication (JP-A) No. 2006-330587 discloses a display device which is capable of suppressing positional displacement when the heat transfer sheet is attached to a heat dissipation member and of easily confirming the present of absent of the heat transfer sheet. In JP-A No. 2006-330587, as an embodiment, round holes are provided as penetration parts formed at positions corresponding to diagonal opposite corners of the heat transfer sheet in the heat dissipation member.
As described above, the silicone rubber having high thermal conductivity is used as the heat conductive sheet (the heat transfer sheet). On the other hand, when the heat conductive sheet (the heat transfer sheet) is disposed between the electronic component (the IC component) and the metal case, the heat conductive sheet (the heat transfer sheet) is sandwiched between the metal case and the electronic component (the IC component) with it pressed therebetween. Inasmuch as the silicone rubber is made of an elastic body, the heat conductive sheet (the heat transfer sheet) gets longer by the above-mentioned pressing.
As a result, when the penetration parts (the round holes) are provided at the positions corresponding to the diagonal opposite corners of the heat transfer sheet in the heat dissipation member, as described in the above-mentioned JP-A No. 2006-330587, there is in danger of arising the heat conductive sheet (the heat transfer sheet) from the penetration parts (the round holes).
It is therefore an object of this invention to provide a tuner module which is capable of preventing a heat conductive sheet from arising and of easily confirming the presence or absence of the heat conductive sheet.
It is another objet of this invention to provide a tuner module which is capable of preventing positional displacement of the heat conductive sheet on attaching the heat conductive sheet to a metal case.
Other objects of this invention will become clear as the description proceed.
On describing the gist of an exemplary aspect of this invention, a tuner module includes a circuit board, an electronic component, mounted on the circuit board, for demodulating a high frequency reception signal received from an antenna unit to produce a speech signal, a metal case accommodating the circuit board and the electronic component therein, and a heat conductive sheet disposed between the electronic component and the metal case. The heat conductive sheet is made of an elastic body. According to this invention, the heat conductive sheet has dimensions which are substantially equal to or slightly lower than outer dimensions of the electronic component, and the metal case has at least one slit-shaped hole which is formed along an outer shape of the electronic component.
Referring to
Herein, in the manner shown in
The illustrated tuner module 100 shows an (inverted mounted) example where it is transversely mounted on a main surface of a main board of a car stereo. However, this invention may be, of course, applicable to a (portrait mounted) case where the tuner module is longitudinally mounted on the main surface of the main board of the car stereo.
Hereinbelow, description will be given of a case where this invention is applied particularly to an automobile digital radio receiver among satellite digital radio receivers, one example of which was explained with reference to
The tuner module 100 comprises the metal case (a sheet-metal case; a shielded case) 10 which will later be described and the printed wiring board (the circuit board) 20. The metal case (the sheet-metal case; the shielded case) 10 comprises a first case 11 and a second case 12. Inasmuch as the tuner module 100 is a type where it is transversely mounted on the main surface of the main board of the car stereo that extends in a horizontal direction, the first case 11 is called an upper case while the second case 12 is called a lower case.
For reference sake, in a case where the tuner module 100 is longitudinally mounted on the main surface of the main board, the first and the second cases 11 and 12 are used as front and rear cases, respectively.
In the example being illustrated, each of the upper case 11 and the lower case 12 is made by bending a metal plate.
The upper case 11 substantially has a box shape without a bottom plate portion (a lower plate portion). Specifically, the upper case 11 has an upper plate portion 11a which substantially extends in parallel with an X-Y plane defined by the fore-and-aft direction X and the left-and-right direction Y. The upper case 11 further has a front plate portion 11b and a rear plate portion (a back plate portion) 11c which are opposite to each other in the fore-and-aft direction X, and has a right plate portion 11d and a left plate portion 11e which are opposite to each other in the left-and-right direction Y.
On the other hand, the lower case 12 substantially has a box shape without an upper plate portion. Specifically, the lower case 12 has a bottom plate portion (a lower plate portion) 12a which substantially extends in parallel with the X-Y plane defined by the fore-and-aft direction X and the left-and-right direction Y. The lower case 12 further has a front plate portion (not shown) and a rear plate portion (not shown) which are opposite to each other in the fore-and-aft direction X, and has a right plate portion 12d and a left plate portion 12e which are opposite to each other in the left-and-right direction Y.
The printed wiring board (the circuit board) 20 is placed in a space between the upper and lower cases 11 and 12, except its portions necessary for electrical connection to the exterior (that will later be described), so as to be shielded. In the example being illustrated, the printed wiring board (the circuit board) 20 is fixed with it sandwiched in the lower case 12.
The printed wiring board (the circuit board) 20 has a substantial rectangular plate shape which extends in parallel with the X-Y plane defined by the fore-and-aft direction X and the left-and-right direction Y. The printed wiring board (the circuit board) 20 has an upper surface 20a and a lower surface (a bottom surface) 20b which are opposite to each other in the up-and-down direction Z. The printed wiring board (the circuit board) 20 has a right side 20c and a left side 20d which are opposite to each other in the left-and-right direction Y, and has a front side 20e and a rear side (a back side) 20f which are opposite to each other in the fore-and-aft direction X. The upper case 11 is disposed at the upper surface 20a side of the printed wiring board (the circuit board) 20 while the lower case 12 is disposed at the lower surface (the bottom surface) 20b side thereof.
As shown in
That is, on the printed wiring board (the circuit board) 20, the first through the third IC components 21 to 23 are mounted as electronic components for demodulating a high frequency reception signal received from an antenna unit (not shown) to produce a speech signal. The second IC component 22 has a rectangular parallelepiped shape, as apparent from
As shown in
Although illustration is omitted, a heat conductive sheet is bonded to the top surface (herein, the whole top surface) of the third IC component 23 or the inner surface of the metal case 10 (an inner wall of the bottom plate portion 12a of the lower case 12).
It should be noted that the heat conductive sheet 32 has dimensions which are substantially equal to or slightly lower than outer dimensions of the second IC component (the electronic component) 22 in a state prior to the above-mentioned press.
In addition, it should be also noted that the heat conductive sheet (not shown) bonded to the top surface of the third IC component 23 has dimensions which are substantially equal to or slightly lower than outer dimensions of the third IC component (the electronic component) 23 in a state prior to the above-mentioned press.
As shown in
As shown in
The RF connector 30 is mounted to the tuner module 100 with it protruded in a left direction toward a left lower place of the tuner module 100 (e.g., at a position close to the left plate portion 11e).
As shown in
In other words, as shown in
Inasmuch as the four L-shaped slit-shaped holes 111 are formed to the metal case 10 along the outer shape of the electronic component 22 and the region 112 enclosed by the four L-shaped slit-shaped holes 111 is substantially equal to that of the outer dimensions of the electronic component 22 in the exemplary embodiment, it is possible to prevent the heat conductive sheet 32 from arising from the slit-shaped holes 111 by pressing of the metal case 10. This is because, on non-pressing, the heat conductive sheet 32 has dimensions which are substantially equal to or slightly lower than outer dimensions of the electronic component 22. On the other hand, inasmuch as the heat conductive sheet 32 gets longer by the above-mentioned pressing of the metal sheet 10 as shown in
Furthermore, inasmuch as the four L-shaped slit-shaped holes 111 are disposed to the positions corresponding to the corner portions of the electronic component 22 and the region 112 enclosed by the four L-shaped slit-shaped holes 111 are substantially equal to that of the outer dimensions of the second IC component (the electronic component) 22, it is possible to minimize displacement of affixation positions in any direction of left-and-right, fore-and-aft, and a slanting on bonding the heat conductive sheet 32 to the inner wall of the upper plate portion 11a of the metal case 10 (the upper case 11). It is therefore to prevent positional displacement of the heat conductive sheet 32 with respect to the electronic component 22.
Likewise, although illustration is omitted, the bottom plate portion 12a of the lower case 12 of the metal case 10 has four slit-shaped holes which are formed along an outer shape of the third IC component (electronic component) 23. These four slit-shaped holes are disposed to positions corresponding to corner portions of the third IC component (electronic component) 23. Each slit-shaped hole has an L shape.
In the tuner module 100 according to the exemplary aspect of this invention, the metal case 10 desirably may have at least two slit-shaped holes 111 at positions which are opposite to each other. The electronic component 22 may have a rectangular parallelepiped shape. In this event, the slit-shaped holes preferably may be disposed at positions corresponding to corners of the electronic component 22. The slit-shaped holes 111 may be equal in number to four. Each of the slit-shaped holes 111 desirably may have an L shape. The heat conductive sheet 32 preferably may be made of silicone rubber.
An exemplary advantage according to the invention is that it is possible to prevent the heat conductive sheet from arising and to easily confirm the presence or absence of the heat conductive sheet. This is because, the heat conductive sheet disposed between the electronic component and the metal case has dimensions which are substantially equal to or slightly lower than outer dimensions of the electronic component, and the metal case has at least one slit-shaped hole which is formed along an outer shape of the electronic component.
While this invention has been particularly shown and described with the reference to the exemplary embodiment thereof, the invention is not limited to the embodiment. It will be understood by those of ordinary skill in the art that various changes in form and details may be therein without departing from the sprit and scope of the present invention as defined by the claims. For example, although the metal case has the four L-shaped slit-shaped holes which are formed along the outer shape of the electronic component in the above-mentioned exemplary embodiment, as a matter of course, the shape and the number of the slit-shaped holes are not limited to them. For instance, the metal case may have at least two slit-shaped holes at positions opposite to each other. Each slit-shaped hole may have a straight-line shape. If it just may inhibit to forget about sticking up the heat conductive sheet, the metal case may have only one slit-shaped hole. In addition, although the slit-shaped holes are disposed to the positions corresponding to the corners of the electronic component in the above-mentioned exemplary embodiment, as a matter of course, the positions where the slit-shaped holes are disposed are not limited to this. At any rate, the metal case may have at least one slit-shaped hole along the outer shape of the electronic component.
This invention is particularly suitable for a tuner module in an automobile digital radio receiver requiring miniaturization, but is of course applicable to the whole range of radio receivers that require heat radiation because of using electronic components.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-223791 | Sep 2009 | JP | national |
