Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – Wire distribution
Reexamination Certificate
1998-03-05
2001-06-12
Gandhi, Jayprakash N. (Department: 2841)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
Wire distribution
C361S826000, C174S0720TR
Reexamination Certificate
active
06246591
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a power cable arrangement structure in an electronic apparatus such as a facsimile machine, printer, copying machine or image scanner.
2. Description of the Related Art
A facsimile machine is an electronic apparatus used for transmitting and receiving image data to and from a remote facsimile machine through a telephone line. For this purpose, the facsimile machine incorporates a modem and a network control unit (NCU) provided with a transformer. The modem and the NCU may be disposed on a power circuit board. Further, the facsimile machine also incorporates a printhead mounted on a signal processing circuit board which receives and processes the image data from the modem or an image reading unit.
The power circuit board of the facsimile machine is connected to a commercial power outlet of e.g. AC 100V and to the signal processing circuit board. The power supply circuit on the power circuit board converts the AC power voltage to a DC power voltage of 6-24V for use on the signal processing circuit board. The electrical connection between the power circuit board and the signal processing circuit board is established by a suitable number of power cables which include at least one power supply cable for supplying the DC power and at least one power return cable for passage of return current to the power circuit board.
Due to the limitation of available space within the facsimile machine, the power cables are inevitably arranged to extend near the transformer if the power cables are connected to the signal processing circuit board. Further, a relatively large current flows through the power cables, so that a relatively strong magnetic field is concentrically around the respective power cables. Thus, if the power supply through the power cables is switched on and off, the intensity of the magnetic field varies with time due to electromagnetic induction. As a result, the nearby transformer and/or the nearby circuit boards are likely to suffer noises.
One way to solve this problem is to enclose the transformer in a magnetic shield conductor and/or to interpose a magnetic shield conductor plate between the power cables and the nearby circuit board. However, such a solution is disadvantageous in that an additional insulation is required for avoiding electrical shorting between the magnetic shield conductor and the transformer (and/or the nearby circuit board), which may lead to a structural complication of the electronic apparatus and an increase in the required number of components while also increasing the assembly steps.
Another solution is to surround the outer insulation sheath of each power cable with a copper wire net which is grounded for magnetic shielding. The use of the grounding wire net will result in an added cost. Further, there is also additional steps of surrounding the power cable with the copper wire net and of grounding the wire net.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention is to provide a power cable arrangement structure which is capable of reliably preventing a transformer from being adversely affected by the presence of the power cables.
According to one aspect of the present invention, there is provided a power cable arrangement structure in an electronic apparatus, the cable arrangement structure comprising: a first control board; a transformer mounted on the first control board; a second control board spaced from the first control board; a connector mounted on the second control board in facing relation to the transformer; and a plurality of power cables extending from the connector, the plurality of power cables including at least one power supply cable and at least one power return cable; wherein the plurality of power cables are bundled together at an intermediate portion.
With the power cable arrangement described above, since the current flow direction in the power supply cable is opposite to that in the power return cable, the magnetic fields generated around the respective power cables offset each other. Thus, it is possible to prevent the transformer from being adversely influenced by the magnetic fields of the power cables.
The plurality of power cables may be bundled together by a separate bundling device such as a belt, clamp or clip which is a relatively inexpensive element. Thus, the addition of the bundling device does not result in a higher cost than adopting other countermeasure for the same purposes.
Alternatively, the plurality of power cables may be bundled together by twisting themselves. Such an arrangement is advantageous in reducing the overall cost.
The power cable arrangement structure may further comprise a separation plate made of an electrically insulating material and provided between the first control board and the second control board, and the plurality of power cables may be made to extend along the separation plate at the intermediate portion. In this case, the plurality of power cables can be reliably prevented from unduly sagging toward the transformer. As a result, the adverse influences, on the transformer, of the magnetic fields of the power cables can be even more reduced.
In a preferred embodiment, the transformer is used for network control for a telephone line, whereas the second control board supports a printhead. Such an arrangement may typically apply to a facsimile machine.
The power cable arrangement structure may further comprise a power circuit board connected to the plurality of power cables via a second connector, and the power circuit board may be arranged in a plane which also contains the first control board.
According to another aspect of the present invention, there is provided a power cable arrangement structure in an electronic apparatus, the cable arrangement structure comprising: a first control board; a transformer mounted on the first control board; a second control board spaced from the first control board; a first connector mounted on the second control board in facing relation to the transformer; a second connector connected to a power supply circuit; and a plurality of power cables extending between the first connector and the second connector, the plurality of power cables including at least one power supply cable and at least one power return cable; wherein the plurality of power cables are bundled together at an intermediate portion by a separate bundling device.
According to a further aspect of the present invention, there is provided a power cable arrangement structure in an electronic apparatus, the cable arrangement structure comprising: a first control board; a transformer mounted on the first control board; a second control board spaced from the first control board; a first connector mounted on the second control board in facing relation to the transformer; a second connector connected to a power supply circuit; and a plurality of power cables extending between the first connector and the second connector, the plurality of power cables including at least one power supply cable and at least one power return cable; wherein the plurality of power cables are bundled together at an intermediate portion by twisting themselves.
Other objects, features and advantages of the present invention will be apparent from the detailed description of a preferred embodiment given below with reference to the accompanying drawings.
REFERENCES:
patent: 5380222 (1995-01-01), Kobayashi
patent: 5469335 (1995-11-01), Kluth et al.
patent: 5534665 (1996-07-01), Long
patent: 5676552 (1997-10-01), Fukuda et al.
Ikeda Akihiro
Matsunaga Keiichi
Brother Kogyo Kabushiki Kaisha
Gandhi Jayprakash N.
Oliff & Berridg,e PLC
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