Electrical connectors – With insulation other than conductor sheath – Metallic connector or contact secured to insulation
Reexamination Certificate
2000-07-05
2001-10-30
Sircus, Brian (Department: 2839)
Electrical connectors
With insulation other than conductor sheath
Metallic connector or contact secured to insulation
C439S825000, C439S439000, C439S751000
Reexamination Certificate
active
06309259
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a metal terminal to be installed on an electrical circuit substrate, and to an electrical circuit substrate on which such a terminal is installed.
2. Description of the Related Art
There is disclosed in Laid-Open Japanese Utility Model Application No. 63-72863 a metal terminal to be installed on an electrical circuit substrate. The metal terminal includes an elastic contact part, which is inserted into an installing hole of the circuit substrate and elastically contacts the inner peripheral surface of the installing hole, and a stop portion for preventing insertion of the metal terminal beyond a predetermined insertion position. When the metal terminal has been inserted, it is prevented to some extent from accidentally moving in the withdrawal (pull-out) direction by frictional resistance of the installing hole to the elastic contact part, and it is prevented from accidentally moving further in the insertion direction by the stop portion.
The terminal can be pulled out from the installing hole, for maintenance. However, there is no means for reliably preventing accidental movement of the terminal in the pull-out direction. Thus, it is impossible to completely prevent the accidental movement of the terminal in the insertion or pull-out direction. This can lead to the metal terminal making poor contact with the inner peripheral surface of the installing hole.
U.S. Pat. No. 2,755,453 discloses a metal terminal having a means for securely preventing accidental movement of the terminal in the pull-out direction. The terminal has a stop member for preventing insertion of the terminal beyond a predetermined position and a locking portion for preventing the terminal from being removed from the installing hole. The terminal is locked at one end of the installing hole by plastically deforming the locking portion when the terminal is stopped at the other end by the stop member. In this way pull-out of the terminal can be reliably prevented, and the terminal can be prevented from accidentally moving in either the insertion or the pull-out direction. However, it is difficult to restore the plastically deformed locking portion to its original shape. Thus, the terminal cannot be easily withdrawn for maintenance.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a metal terminal which affords easy maintenance and is reliably prevented from accidentally moving in a withdrawal direction.
In a first aspect of the invention there is provided a metal terminal for insertion into a contact hole of an electrical circuit substrate and for making electrical contact with the contact hole when the terminal is at a predetermined position in the contact hole. The terminal includes a stop member which abuts the substrate at the rearward end of the contact hole relative to the insertion direction when the terminal is at the predetermined position, thereby preventing further insertion of the terminal. The terminal also includes a removal resistance portion which abuts the substrate at the forward end of the contact hole relative to the insertion direction when the terminal is at the predetermined position, thereby resisting accidental movement of the terminal in the withdrawal direction. The removal resistance portion is resiliently deformable to allow it to pass through the contact hole during insertion of the terminal.
When the metal terminal is inserted into the contact hole, the removal resistance portion abuts the substrate at the end of the contact hole, thus reliably helping to prevent the metal terminal from accidentally moving in the withdrawal direction. However, the removal resistance portion can resiliently deform to allow the metal terminal to pass through the contact hole. Thus, the metal terminal fitting can be withdrawn from the installing hole, e.g. for maintenance.
It is preferable that the removal resistance portion includes a pair of laterally spaced resiliently deformable locking members which are shaped so as to be urged towards each other when the terminal is moved in the withdrawal direction. Because the locking members can be urged towards each other, on withdrawal of the metal terminal from the contact hole, the locking members deform elastically to allow the removal resistance portion to pass through the contact hole.
Preferably the locking members have, at their rear sides with respect to the insertion direction, opposite outer surfaces which are inclined with respect to the insertion direction and mutually taper in the direction opposite to the insertion direction, whereby the locking members, by contact between the outer surfaces and the forward end of the contact hole, urge the terminal in the insertion direction during insertion. This assists insertion of the terminal to the correct position.
It is preferable that the terminal further comprises, between the stop member and the removal resistance portion, a pair of resiliently deformable contact members for bearing resiliently on an inner surface of the contact hole. More preferably the contact members are laterally spaced from each other. Because the resilient contact members bear resiliently on the inner surface of the contact hole, the terminal can be prevented from accidentally moving in a direction sideways relative to the axis of the contact hole.
When the metal terminal has both the locking members and contact members described above, the contact members may connect with the locking members so that the contact members are displaced towards each other when the locking members are urged together.
For example, a gap formed between the locking members may be continuous with a gap formed between the contact members, so that when the locking members deform elastically, the contact members also deform elastically. In this way frictional resistance due to contact member-contact hole interaction can be reduced when the terminal is withdrawn from the contact hole.
In a further aspect, the present invention provides an electrical circuit substrate having a contact hole into which is inserted a metal terminal as described above. Typically the substrate has electrical circuit elements on at least one of its surfaces, and the terminal makes electrical contact with such a circuit element via a conductive layer in the contact hole.
It is preferable that the removal resistance portion of the terminal bears resiliently on an outer face of the substrate at the forward end of the contact hole relative to the terminal insertion direction. Because the removal resistance portion performs its removal resistance function in this manner, it is possible to prevent the terminal from shaking or vibrating in the contact hole.
REFERENCES:
patent: 2755453 (1956-07-01), Cloutier
patent: 4676579 (1987-06-01), Ting
patent: 4763408 (1988-08-01), Heisey et al.
patent: 4790764 (1988-12-01), Kawaguchi
patent: 5078617 (1992-01-01), Gutierrez et al.
patent: 6050842 (2000-04-01), Ferrill et al.
patent: 0 899 819 A2 (1999-03-01), None
patent: 0 899 819 A3 (2000-06-01), None
patent: 2 245 770 A (1992-08-01), None
patent: U-63-72863 (1988-05-01), None
Oliff & Berridg,e PLC
Prasad Chandrika
Sircus Brian
Sumitomo Wiring Systems Ltd.
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