Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
1995-02-09
2002-05-14
Thompson, Gregory (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C062S259200, C454S184000
Reexamination Certificate
active
06388879
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a circuit board packaging structure and, more particularly to a circuit board packaging structure in switching equipment.
2. Description of the Related Art
In recent years, there has been offered a variety of communications systems utilizing optical cables each composed of an optical fiber exhibiting a high transmission efficiency. For example, a circuit transmission line may be formed by use of the optical cables in Broadband-ISDN system, such as asynchronous transfer mode (ATM) switching equipment and also in an integrated services digital network (ISDN) network. Accordingly, the ATM switching equipment includes a photoelectric converting portion for converting a transmitted optical signal into an electrical signal and converting the electrical signal into the optical signal when transmitting the electrical signal to a circuit transmission line. Then, the optical cable is connected via an optical connector to the photoelectric converting portion. Hereinafter, a configuration having the above optical connector and the photoelectric converting portion is termed as an optical module.
When the thus structured optical modules are mounted in a box body of the switching equipment, according to the prior art construction, the optical connectors are disposed together with the photoelectric converting portions inwardly of the board in the box body. With this arrangement, the optical cables have to be connected to the optical connectors by perforating the board and guiding the optical cables therethrough. That is, the connector normally has a male connector connected to the end of the optical cable and a female connector connected to the photoelectric converting portion. These male and female connectors are disposed together inwardly of the board, and hence the optical cable has to penetrate the board.
Further, according to a packaging structure of a circuit in an electric mechanical apparatus, there may be a case in which packaging involves dividing one circuit into a plurality of modules, individually mounting these modules on separate circuit boards and, at the same time, connecting these circuit boards to each other. In this case, a plurality of circuit boards are connected perpendicularly to one sheet of circuit board (Back Wiring Board (hereinafter abbreviated to [BWB]) so that the plurality of circuit boards are parallel to each other. This construction is known as a bookshelf construction.
A transmission line corresponding unit of the switching equipment needs one optical module per subscriber's transmission line. It is necessary for the board to be perforated by two holes because photoelectric connections must be made to two lines of optical cables within one optical module. Then, normally in the switching equipment, the board has to be perforated with a total of sixteen holes in order to accommodate eight subscriber transmission lines.
Thus, when the number of holes increases, the strength of the board decreases, possibly resulting in the board becoming warped. Further, a large plurality of wires must be arranged on the board. Problems may arise due to the presence of the holes which hinder the degree of freedom in the wiring design. In addition, this contributes to a reduction in the area capable of accommodating wires and to a decline in wire accommodatability.
It is a first object of the present invention to provide a circuit board packaging structure that does not require perforating a board with holes, that provides a degree of freedom for wiring design on the board and prevents a decline in wire accommodatability in equipment using such optical modules.
Further, in the case of adopting the above-mentioned bookshelf construction, a problem arises as to how to apply cooling air for cooling circuit elements on each circuit board in order to improve a cooling efficiency. In particular, if high exothermic elements (e.g., LSIs, etc.) are contained in the circuit elements, a decision must be made as to which circuit board should be used for mounting these high exothermic elements and how to expose them to the cooling air.
It is a second object of the present invention to provide a circuit board packaging structure capable of obviating the above problem, when packaging an electric circuit on a circuit board based on the bookshelf construction, and positively cooling off circuit elements exhibiting a comparatively high exothermic quality.
Also, in the case of using the above bookshelf construction, if an element requiring maintenance and inspection is contained in the circuit elements, there are problems which follow. That is, when opening a door of the electric mechanical apparatus and exposing the circuit board to the outside, maintenance and inspection purposes, a large quantity of cooling air will flow out of this opened door so that not enough cooling air will circulate along the peripheries of the circuit elements except for this element. Thus, during the maintenance and inspection of some elements, other circuit elements will not be sufficiently cooled off. Hence, even if some circuit elements are usable, this electric mechanical apparatus as a whole may be brought into an inoperable state.
It is a third object of the present invention to provide a circuit board packaging structure that is capable of obviating the above problem and performing the maintenance and inspection of some circuit elements without influencing the cooling air flowing to other elements.
Moreover, up until now the above bookshelf construction has not been proposed for ATM switching equipment. Accordingly, in the conventional switching equipment, the circuits are packaged on a single circuit board or on a plurality of circuit boards arranged in parallel. By the way, in ATM switching equipment, a transmission line corresponding unit for accommodating transmission lines extending from subscriber's terminals or junction transmission lines from other switching equipment includes firmware exhibiting a function only selectively utilized. In the case of the conventional circuit board, however, it is impossible to eliminate the firmware having the function which is not utilized. Hence, with respect to all the transmission line corresponding units, all kinds of firmware have to be packaged irrespective of whether or not the functions thereof are utilized. For this reason, the equipment increases in size on the whole, and, at the same time, the dissipation of electric power unnecessarily increases.
It is a fourth object of the present invention to provide a circuit board packaging structure that is capable of obviating the above problem and easily eliminating the firmware having the non-utilized function out of the transmission line corresponding unit of the ATM switching equipment.
SUMMARY OF THE INVENTION
According to the present invention, the following constructions and elements are taken for obviating the respective problems given above.
According to a first aspect of the present invention, there is provided a construction for obviating the first problem described above. That is, there is provided a circuit board packaging structure, comprising: an optical cable; an optical module having a photoelectric converting portion connected to the optical cable; and a circuit board including an electric circuit unit in an internal portion thereof. The optical cable and the optical module are disposed on an external portion of the circuit board. The electric circuit unit provided on the internal portion of the circuit board and the optical module are electrically connected to each other through an electric conductor traversing the circuit board.
According to a second aspect of the present invention, there is provided a construction for obviating the second problem given above. That is, there is provided a circuit board packaging structure, comprising: a plurality of circuit boards each packaged with electric circuit parts and disposed parallel to each other. The circuit board packaged with the electric circuit
Ashida Takayuki
Fujita Shuuhei
Nakajima Hidenao
Otaguro Hiroyuki
Watanabe Yoshimi
Fujitsu Limited
Rosenman & Colin LLP
Thompson Gregory
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