Electricity: conductors and insulators – Conduits – cables or conductors – Preformed panel circuit arrangement
Reexamination Certificate
2000-10-17
2002-10-15
Cuneo, Kamand (Department: 2827)
Electricity: conductors and insulators
Conduits, cables or conductors
Preformed panel circuit arrangement
C174S051000, C174S050510, C361S811000, C361S808000
Reexamination Certificate
active
06465746
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an oscillator attachment structure used in e.g. a head end of CATV transmitter.
2. Description of the Related Art
A conventional oscillator attachment structure will be described with reference to
FIGS. 4
to
6
. An oscillator
31
has a box-shaped frame body
32
of metal plates having attachment legs
32
a
, a circuit board
35
having a wiring pattern
33
on its upper surface and a ground conductor
34
on its approximately entire lower surface, various electric components
36
soldered to the wiring pattern
33
, connection pins
37
soldered to the wiring pattern
33
and projecting downward through the circuit board
35
, and a metal cover
38
over the frame body
32
.
Further, the connection pins
37
include plural power-source connection pins
37
a
provided in left and right positions, a tuning connection pin
37
b
, an output connection pin
37
c
and a ground connection pin
37
d
positioned between the power-source connection pins
37
a
. The connection pins
37
are not electrically connected to the ground conductor
34
, being isolated from the ground conductor
34
by relief members
34
a
comprising rejection members provided in the ground conductor
34
.
A printed circuit board
41
comprising a mother board that forms a head end of the transmitter holds a ground conductive member
42
on its upper surface, a wiring pattern
43
on its lower surface, and various electric components
44
soldered to the wiring pattern
43
, and the.
Further, a buffer member
45
is formed with a rubber member
46
and adhesive
47
provided on the lower surface of the rubber member
46
. The rubber member
46
is insulating and formed in a plate, i.e. planar, shape. The buffer member
45
is attached to the upper surface of the ground conductive member
42
of the printed circuit board
41
by the adhesive
47
.
Further, a PLL circuit (not shown) is formed in the wiring pattern
43
opposite to the buffer member
45
.
In the above-described oscillator
31
, the attachment legs
32
a
of the frame body
32
and the power-source connection pins
37
a
are inserted into holes of the printed circuit board
41
, and the tuning connection pin
37
b
, the output connection pin
37
c
and the ground connection pin
37
d
are inserted through holes of the buffer member
45
and the printed circuit board
41
. The lower surface of the circuit board
35
is disposeddisposed on the rubber member
46
. In this state, the connection pins
37
and the attachment legs
32
a
are soldered to the wiring pattern
43
, thus the oscillator
31
is mounted on the printed circuit board
41
.
The power-source connection pins
37
a
and the tuning connection pin
37
b
are not electrically connected to the ground conductive member
42
by the relief members
42
a.
In the oscillator attachment structure having the above construction, fluctuations of an oscillation waveform from the oscillator
31
due to shock and vibration from the printed circuit board
41
side, e.g. f skip, are prevented by the buffer member
45
.
However, as the rubber member
46
of insulating material is used, a capacitance formed between the ground conductor
34
of the circuit board
35
and the ground conductive member
42
of the printed circuit board
41
is small. One result of this is that the circuit board
35
is not sufficiently grounded to the printed circuit board
41
in a so-called electrically floating state.
As a result, a reference oscillation signal from the PLL circuit formed on the printed circuit board
41
side influences the circuit board
35
side. The signal is mixed with the oscillation signal from the oscillator, which causes a beat signal as an interference signal.
SUMMARY OF THE INVENTION
The present invention has been made in consideration of the above situation, and provides an oscillator attachment structure which prevents an interference signal (more specifically) a beat signal and attains excellent performance.
According to one aspect of the present invention, the foregoing object is attained by providing an oscillator attachment structure comprising: a metal frame and a first circuit board having a first ground conductor on a lower surface thereof. The first circuit board is attached within the frame. A printed circuit board has a second ground conductor on an upper surface thereof. The oscillator is attached to the upper surface of the first circuit board. A conductive rubber plate, electrically connected to the first ground conductor, is provided on the lower surface of the first circuit board, and the conductive rubber plate is disposed on the second ground conductor. Further, according to another aspect of the present invention, the foregoing object is attained by providing an oscillator attachment structure comprising: a metal frame and a first circuit board having a first ground conductor on a lower surface thereof. The first circuit board is attached within the frame. A printed circuit board has a second ground conductor on an upper surface thereof. An oscillator is attached to an upper surface of the first circuit board. A thin insulating member disposed on the second ground conductor. A conductive rubber plate, electrically connected to the first ground conductor, is provided on the lower surface of the first circuit board, and the conductive rubber plate is disposed on the thin insulating member.
Further, according to another aspect of the present invention, the foregoing object is attained by providing the oscillator attachment structure, wherein the insulating member comprises a double-faced adhesive tape, and wherein the conductive rubber plate and the ground conductor are attached to each other by the double-faced adhesive tape.
Further, according to another aspect of the present invention, the foregoing object is attained by providing the oscillator attachment structure, wherein conductive grease is provided between the conductive rubber plate and the first ground conductor.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same name or similar parts throughout the figures thereof.
REFERENCES:
patent: 4034318 (1977-07-01), Ishiyama et al.
patent: 4855869 (1989-08-01), Tsuji
patent: 4860166 (1989-08-01), Nicholls
patent: 5311402 (1994-05-01), Kobayashi et al.
patent: 6075700 (2000-06-01), Houghto et al.
patent: 6239360 (2001-05-01), Kato et al.
patent: 0910163 (1999-04-01), None
patent: 10252178 (1998-09-01), None
patent: 11-186845 (1999-07-01), None
European Search Report, issued Mar. 19, 2002, corresponding to EPA No. 00308956.2
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Cuneo Kamand
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