Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
1998-01-16
2001-01-09
Gaffin, Jeffrey (Department: 2841)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S799000, C361S800000, C361S816000, C361S818000, C174S034000
Reexamination Certificate
active
06172881
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of interconnecting the frame grounds in a housing so as to suppress radiation noise from the cable between circuit boards, and an electronic equipment with a structure connected by the method.
2. Related Background Art
Conventionally, the frame grounds in a housing are interconnected, as shown in FIG.
9
. More specifically, in a housing including circuit boards
2
1
and
2
2
, the housing or plate metals
1
1
and
1
2
connected to the housing are connected as frame grounds FG to the board grounds via members
5
1
and
5
2
as means for reinforcing the board grounds so as to take a measure against radiation noise from the circuit boards
2
1
and
2
2
. The circuit boards
2
1
and
2
2
are connected to each other by a cable
4
via connectors
3
1
and
3
2
, and the cable
4
uses a shield cable as a measure against its radiation noise.
However, in the prior art, when the circuit boards
2
1
and
2
2
are connected by the cable
4
, different plate metals
1
1
and
1
2
are often connected to the circuit boards
2
1
and
2
2
in consideration of the layout in the housing.
FIG. 10
illustrates the state between such different plate metals
1
1
and
1
2
, i.e., different frame grounds. When the circuit boards
2
1
and
2
2
are connected to different frame grounds FG
1
and FG
2
, these frame grounds FG
1
and FG
2
normally have different ground potentials Vg
1
and Vg
2
, and a potential difference Vgc between these ground potentials is called a common mode potential. When the circuit boards
2
1
and
2
2
connected to the frame grounds FG
1
and FG
2
with different ground potentials Vg
1
and Vg
2
are connected by the cable
4
, a common mode current Ic owing to the common mode potential concentratively flows through the cable
4
, and common mode noise is radiated from the cable
4
. Such common mode noise cannot be sufficiently shielded by the shield cable, and it is very difficult to solve this noise problem.
SUMMARY OF THE INVENTION
It is an object of the present invention to solve the above-mentioned problems, and to provide a method of interconnecting the frame grounds in a housing, which can suppress radiation noise produced from the cable between circuit boards by reducing the potential difference between the frame grounds in the housing, and an electronic equipment with a structure interconnected by the method.
It is another object of the present invention to interconnect frame grounds via a conductive member at their neighboring positions.
Other objects of the present invention will become apparent from the following detailed description of the embodiments.
REFERENCES:
patent: 5432486 (1995-07-01), Wong
patent: 5469336 (1995-11-01), Soulard
patent: 5519584 (1996-05-01), Siraky
patent: 5523695 (1996-06-01), Lin
patent: 5604668 (1997-02-01), Wohrstein et al.
patent: 5680297 (1997-10-01), Price et al.
patent: 5717556 (1998-02-01), Yanagida
patent: 5742484 (1998-04-01), Gillete et al.
patent: 5917149 (1999-06-01), Barcley et al.
Canon Kabushiki Kaisha
Dinh Tuan
Fitzpatrick ,Cella, Harper & Scinto
Gaffin Jeffrey
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