Electricity: conductors and insulators – Conduits – cables or conductors – Preformed panel circuit arrangement
Reexamination Certificate
2002-10-03
2004-11-16
Pert, Evan (Department: 2827)
Electricity: conductors and insulators
Conduits, cables or conductors
Preformed panel circuit arrangement
C174S261000, C174S262000, C361S760000, C361S804000, C439S065000
Reexamination Certificate
active
06818837
ABSTRACT:
This nonprovisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No. 2001-313678 filed in JAPAN on Oct. 11, 2001, which is herein incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a wiring connection structure for establishing electrical connection between circuit boards on which circuits for processing high frequency signals and intermediate frequency signals are provided. The present invention also relates to a transmitter in which wires are connected using the wiring connection structure.
2. Description of the Background Art
Recently, as the field of wireless communication has been developed remarkably, various devices for wireless communication have been developed and used widely. In these devices used for wireless communication, electromagnetic waves generated from circuits pose a significant problem, as signals having relatively high frequency, such as high frequency signals and intermediate frequency signals are used.
A common solution to this problem is to surround a circuit board with a conductive material to form an electromagnetic shield, so as to prevent undesirable influence on other external or internal circuitry. When there are a plurality of circuit boards, it is necessary to electrically connect the circuit boards with each other. Therefore, the wiring connection structure comes to be of greater importance, considering relation with the conductive material forming the electromagnetic shield. In the following, a transmitter transmitting microwaves will be considered as a representative example of the device of this type, and the structure thereof will be described.
Wireless communication using microwaves has been developed explosively in these days, in many systems including broadcasting satellite and communication satellite. At the same time, there is an increasing demand for bi-directional communication, along with the development of the Internet and a start of digital BS (Broadcasting Satellite) service. In bi-directional communication involved in satellite communication, reception can be done using an LNB (Low Noise Block down converter) as in the prior art, while transmission requires a new transmitter.
FIG. 3
is a block diagram showing an example of a circuit mounted on the transmitter. An IF (Intermediate-Frequency) signal and a DC (Direct Current) voltage input through an IF/DC input terminal are input to an IF amplifier circuit
1
and to a power supply circuit
2
, respectively. The IF signal input to IF amplifying circuit
1
is subjected to appropriate amplification, and thereafter, fed to an RF (Radio-Frequency) amplifier circuit
3
. The IF signal input to RF amplifier circuit
3
is mixed with a local oscillation signal that has also been input to RF amplifier circuit
3
from a local oscillation circuit
4
, and has its frequency converted to be an RF signal having higher frequency than the IF signal. The thus converted RF signal is appropriately amplified by RF amplifier circuit
3
, input to power amplifier
5
to be further amplified to a high power high frequency signal, and output from the transmitter.
It is often the case that the circuits are provided separately on an IF board
15
having IF amplifier circuit
1
and power supply circuit
2
formed therein, and an RF board
14
having RF amplifier circuit
3
and local oscillation circuit
4
formed therein. The reason for this is that signals flowing through respective circuits differ in frequency, and therefore, it is necessary to select materials of circuit boards that have characteristics more desirable for respective frequencies. Specifically, in view of dielectric constant of the circuit board material, a composite circuit board or the like is used for the IF board through which IF signals having relatively low frequency flow, and a PTFE (polytetra fluoro ethylene) board or the like is used for the RF board through which RF signals of high frequency flow.
Another reason why the circuit board is divided is the reduction in size of the transmitter. When all the circuits are formed on a single circuit board, it is necessary to use a large circuit board, and hence, the transmitter naturally becomes large. When the circuit board is divided and the divided boards are arranged parallel to each other, the size of the transmitter can be reduced.
From the above described reasons, such a structure is often employed in a transmitter that the circuit board is divided into two, that is, the IF board and the RF board, which are connected by a board-to-board connecting wire such as a vinyl covered cable or a coaxial cable.
The structure of this type of transmitter will be described with reference to
FIGS. 4 and 5
. Various components are assembled in a chassis
10
as an outer frame of the transmitter. In the transmitter shown in the figure, chassis
10
has a box shape with rectangular parallelepiped outer shape. Shield plates
11
are provided in the horizontal direction inside the chassis, and by the shield plates
11
, the space inside chassis
10
is divided into three.
In the uppermost one of the three-divided spaces, RF board
14
is accommodated. A frame
16
is assembled above RF board
14
, and further thereon an RF shield lid
17
is provided to seal the uppermost space of the chassis
10
. In the middle space, electric parts such as condensers are mainly accommodated. The condenser is relatively large as compared with other electric components, and it is not mounted on the circuit board but arranged in the middle space of the chassis
10
. Further, in the lowermost space of chassis
10
, IF board
15
is accommodated, and further therebelow, an IF shield lid
18
for sealing the lowermost space of chassis
10
is provided.
Chassis
10
and the shield plate
11
provided on chassis
10
are formed of a conductive material such as metal, so as to prevent leakage to the outside of the electromagnetic waves generated from RF amplifier circuit
3
, IF amplifier circuit
1
or the like as well as to prevent entrance of the electromagnetic waves from the outside. For the same purpose, RF shield lid
17
and IF shield lid
18
are also formed of a conductive material.
The wiring connection structure will be described in detail in the following. Referring to
FIG. 5
, in order to electrically connect RF board
14
accommodated in the uppermost space with IF board
15
accommodated in the lowermost space, a through hole
12
connecting these spaces is provided at prescribed positions in the upper and lower shield plates
11
of chassis
10
. A power supply line
6
and a signal line
7
are inserted to through hole
12
. For such board-to-board connecting wire
20
, a vinyl covered cable or a coaxial cable having a core line
21
covered with an insulating member
22
is used, so as to prevent contact with the chassis
10
.
Further, at such positions of RF board
14
and IF board
15
that are opposite to the through hole
12
of shield plate
11
, through holes
25
and
26
are formed. On the surface of the circuit board at the peripheral edge of the through holes
25
,
26
and on inner wall surfaces of through holes
25
and
26
, an electrode (through hole land)
27
of a conductive material is formed. The core line
21
of the aforementioned board-to-board wiring
20
is inserted to the through holes
25
,
26
and core line
21
is connected to through hole land
27
by solder
28
, whereby electrical connection between RF board
14
and IF board
15
is established.
The connection procedure to realize the above described wiring connection structure is as follows. First, the board-to-board connecting wire that is cut into a prescribed length and has covers at opposite ends peeled off is inserted to the through hole of the chassis of the transmitter. Thereafter, one circuit board is brought into contact with the shield plate of the chassis, and at the same time, a tip end of the core line of board-to-board connecting wire is inserted to the through hole of the circuit board. Then, the other circ
Birch, Stewart, Kolasch Kolasch & Birch, LLP
Patel I B
Sharp Kabushiki Kaisha
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