Board latching device for an edge connector

Abstract: A board latching device (5) is described for use in an edge connector for electrically interconnecting mother and daughter printed circuit boards and in which the daughter board makes electrical connection with contacts of the connector when the daughter board is inserted into the connector in a first position and is rotated, relatively to the connector from the first position to a second latched position. The latching device comprises a retaining section (51) for mounting the device on the connector housing, a latching section (53) for latching the daughter board in its second position, and an unlatching section (54) for releasing the board.

Description: The present invention relates to an electrical edge connector for a PCB (printed circuit board) and, more particularly, to a board latching device to be used with such a connector. An edge connector mounted on a PCB for interconnecting another PCB contains a plurality of contacts along the longitudinal direction thereof for receiving the edge of the other PCB. The edge connector is provided with latching means to latchably hold both edges of the PCBs. Conventionally, the latching means is made from a plastic material and is integral with the connector housing. However, such latching means, made integrally with the housing, are plastic and have inherent problems in that frequent latching and unlatching causes the latching or engaging sections to wear and reduce the latching force to an impractical level. One such connector is described in patent EP-A2-0 276 924 (on which the pre-characterising part of claim 1 is based). The connector includes a housing containing a multiplicity of electrical contacts which housing is connectable to a first PCB. A second edge mounted PCB is retained in the connector by means of yieldable latch projections which are integral with the housing and which engage ends of the second PCB when it has been rotated about one of its edges which has electrical terminals which engage the electrical contacts of the connector. One approach to solving the above problems may be the use of separate metal members mounted on a housing. A metal latch generally provides a stronger latching force and is more durable. However, it requires additional force when unlatching the PCB. It is especially difficult to unlatch a PCB in an electronic apparatus or the like having a plurality of closely disposed connectors. It is an object of the present invention to provide a latching device for such an edge connector having improved latching force, durability and unlatchability suitable for use in an edge connector for electrically interconnecting first and second circuit boards and in which the second board makes electrical connection with contacts of the electrical connector when the second board is inserted into the connector in a first position and is rotated, relative to the connector, from the first position into a second position. Thus, according to the invention, there is provided a latching device for use in an edge connector for electrically interconnecting first and second circuit boards in which the second circuit board makes electrical connection with contacts of the electrical connector when the second board is inserted into the connector in a first position and is rotated, relative to a housing of the connector from the first position into a second position, said latching device being for latching the second circuit board in its second position and having a latching section for engaging with the second circuit board to latch it in its second position, characterised in that said latching device comprises a metal plate member having a U-shaped retaining section for mounting the device on the connector housing and an unlatching section for releasing engagement with the second circuit board, said latching section projecting laterally above and from one side of said U-shaped retaining section and said unlatching section projecting horizontally above said latching section such that said latching section is between said unlatching section and said U-shaped retaining section, whereby downward manual pushing of said unlatching section towards said U-shaped retaining section deforms said latching section transversely with respect to said U-shaped retaining section to release said latching section from engagement with said second circuit board. In order that the present invention may be more readily understood, reference will now be made to the accompanying drawings, in which:- Figure 1 is a plan view of the housing of an edge connector constructed to utilise the present invention; Figure 2 is a front view of the housing in Figure 1; Figure 3 is a front view of the housing having installed board latching devices according to the invention; Figure 4 is an enlarged cross sectional view along the line IV-IV in Figure 3; Figure 5 is a partial enlarged view of the right hand portion of the above housing; Figure 6 is the front view of Figure 5; Figure 7 is the right side view of Figure 5; Figure 8 is a cross sectional view along the line VIII-VIII in Figure 5; Figure 9 is a cross sectional view along the line IX-IX in Figure 6; Figure 10 is a plan view of the board latching device used in the above embodiment; Figure 11 is the right side view of Figure 10; Figure 12 is the front view of Figure 10; Figure 13 is the back view of Figure 10; Figure 14 is the left side view of Figure 10; Figure 15 is the bottom view of Figure 10; Figure 16 is a cross sectional view along the line XVI-XVI of Figure 11; Figure 17 is a cross sectional view of the edge portion of the housing having the board latching device secured in the opening thereof; Figure 18 is a central cross sectional view of the housing having the contacts and the board latching device installed therein (with the latching device hatched); and Figure 19 is a cross sectional view of Figure 18 further having a circuit board mounted thereon. Referring to Figures 1, 2 and 3, the insulation housing 2 of an edge connector 1 has a large number of contacts 3 (see Figure 4) inserted in parallel with each other along the longitudinal direction thereof. Each contact 3 has a tine 31 extending outwardly from the bottom of the housing 2 for making electrical connection with one of two PCBs. There are two openings 21 at both ends of the housing 2 to insert and secure board latching devices 5 for latching another circuit board (as referred to by a reference number 4 in Figure 19). The detailed construction of the both ends is discussed hereinafter by reference to Figures 5 through 9. Also, the detailed construction of the board latching devices 5 will be illustrated in Figures 10 through 16. Referring to Figures 5 through 9, each opening 21 has an elongated receiving cavity 21a for receiving base section 51 of the metal latching device 5 as illustrated in Figures 10 through 16. A slot portion 22 (see Figure 17) having a step portion 22a is provided to engage with a hook portion 52 of the latching device 5 inserted in the opening 21 from the above, thereby preventing the latching device 5 from being pulled out in the above direction. The board latching device 5 is made of a metal plate member and has a board latching section 53 extending laterally with a curved surface 53a above a U-shaped (in cross section) base section 51 having the above mentioned hook section 52. It also has an unlatching portion 54 extending horizontally above the board latching section 53. The unlatching section 54 allows the upper half portion of the latching device 5 as well as the latching section 53 to deform sideways (in the direction A) by pushing it down by a finger, thereby releasing the circuit board 4 latched by the latching section 53. When the circuit board 4 is inserted in the direction B in Figures 10 and 19, a side edge 4a of the circuit board 4 rides over the curved surface 53a of the latching section 53 (by resiliently bending the upper half of the latching device 5) for engagement with the latching section 53. In this manner, the edge of the circuit board 4 is received in the contacts 3 in the housing 2 for making electrical connection. In order to unlatch the circuit board 4, the unlatching section 54 is pushed sideward from above, thereby resiliently deforming the upper half of the latching device 5 outwardly from the engaging location of the latching section 53 with the circuit board 4. As mentioned above, the latching device according to the present invention is made of a metal plate member and comprises the retaining section (the hook section 52 on the base section 51) for mounting on the housing 2, the latching section 53 for engaging with the circuit board 4 and the unlatching section 54 for releasing the engagement. It is,therefore, excellent in mechanical strength, durable and easy to remove the circuit board 4 by simply pushing the unlatching section 54 by a finger. The formation of the curved surface 53a at the latching section 53 allows the engagement with the circuit board 4 to be released by guiding the side edge of the circuit board 4 along the curved surface 53a even if an excessive force is applied to the circuit board 4 from the back side of the connector (e.g. when the operator pushed the circuit board 4 from the back side of the connector by mistake). This is important to prevent the board latching devices 5 and the retaining sections therefor in the housing 2 from being broken. It should be understood that the shape of the board latching device may not be limited to the particular embodiment and may be modified in many ways without departing from the scope of the invention as long as the above mentioned functions are maintained.

Claims: A latching device (5) for use in an edge connector (1) for electrically interconnecting first and second circuit boards in which the second circuit board (4) makes electrical connection with contacts (3) of the electrical connector (1) when the second board (4) is inserted into the connector in a first position and is rotated, relative to a housing (2) of the connector (1) from the first position into a second position, said latching device (5) being for latching the second circuit board (4) in its second position and having a latching section (53) for engaging with the second circuit board (4) to latch it in its second position, characterised in that said latching device (5) comprises a metal plate member having a U-shaped retaining section (51) for mounting the device (5) on the connector housing (2) and an unlatching section (54) for releasing engagement with the second circuit board (4), said latching section (53) projecting laterally above and from one side of said U-shaped retaining section (51) and said unlatching section (54) projecting horizontally above said latching section (53) such that said latching section (53) is between said unlatching section (54) and said U-shaped retaining section (51), whereby downward manual pushing of said unlatching section (54) towards said U-shaped retaining section (51) deforms said latching section (53) transversely with respect to said U-shaped retaining section (51) to release said latching section (53) from engagement with said second circuit board (4). The latching device of claim 1, wherein said latching section (53) includes a curved surface (53a) constituting a camming surface which is arranged to deform said latching section (53) sideways when said camming surface (53a) is engaged by said second circuit board (4) to facilitate movement of said second circuit board (4) between its first and second positions.

Inventors: KAMONO TAKASHI, KUMAGAI NAOKI, NAKAMURA TSUTOMU, NISHIMURA RYOJI, SATO YOSHIO, KAMONO,TAKASHI, KUMAGAI,NAOKI, NAKAMURA,TSUTOMU, NISHIMURA,RYOJI, SATO, YOSHIO
Applicants: WHITAKER CORP, THE WHITAKER CORPORATION
Application year: 1990
Main classification: H01R12
IPC codes: H01R12