WO2012041011A1

WO2012041011A1 - Lc connector assembly with identification information for preventing mis-insertion and lc plug thereof

Info

Publication number: WO2012041011A1
Application number: PCT/CN2011/001635
Authority: WO
Inventors: 余永强; 韩兆春; 黄澄; 李卫可
Original assignee: 中航光电科技股份有限公司
Priority date: 2010-09-30
Filing date: 2011-09-28
Publication date: 2012-04-05
Also published as: CN201845105U

Abstract

An LC connector assembly with identification information for preventing mis-insertion and an LC plug thereof, wherein the LC plug (1) is insertably connected to an LC adaptor (7) via a fixed casing (4) arranged in the form of a socket fitting on a front end; an avoidance opening (23) for making way for a duplex clip (5) is provided on the corresponding side of the fixed casing (4); the avoidance opening (23) extends to the rear end face of the fixed casing (4); rear limit steps (13) for fitting with bosses in rear limit positions at both sides of the duplex clip (5) are provided on both side walls of the avoidance opening (23); a printed board (2) is fixedly provided on the side of the fixed casing (4) opposite to the side provided with the avoidance opening (23); a plug information memory chip (6) is provided on the printed board (2), and two pins of the plug information memory chip (6) are electrically connected to two electrically conductive contacts on the printed board respectively; two flexible metal pieces are provided on the LC adapter (7), which flexible metal pieces are electrically connected to the two electrically conductive contacts respectively when insertion occurs and are electrically connected to a signal input on a system main board.

Description

LC connector assembly with anti-missing identification information and its LC plug

The present invention relates to an LC connector assembly with identification code preventing mis-insertion identification information that prevents the LC plug from being mis-inserted on an unsuitable LC adapter, and to the LC plug of the connector assembly.

Background technique

In places where optical signals are transmitted by base stations, etc., it is sometimes necessary to plug a large number of optical connector plugs into the optical connector adapter of the device to transmit optical signals. There are two types of common standard optical connector assemblies, one is an LC connector. The component, the other is the SC component. The LC connector assembly includes an LC plug and an LC adapter, and the LC plug is square. The front end is for mating with the plug opening of the LC adapter. One side of the LC plug is provided with a front end fixed to the LC plug, and the rear end is inclined rearward. The overhanging duplex clamp has a bump on both sides of the duplex clamp. The plug-in opening of the LC adapter and the side wall of the duplex clip have slots for mating with the duplex clip, and the LC plug and the LC adapter are reliably inserted by the duplex clip.

In the same way as the standard LC plug for transmitting different signals, it is easy to confuse the optical connector plugs that transmit different signals during the plug-in, resulting in mis-insertion. Due to the large number of plugs, it is difficult to detect the insertion, and the wiring is increased. Difficulty.

Summary of the invention

It is an object of the present invention to provide an LC connector assembly with mis-insertion identification information to solve the problem that two or more LC connector assemblies in the prior art are easily inserted into each other during insertion, and the object of the present invention It is also provided to provide an LC plug of the LC connector assembly.

To achieve the above object, the LC connector assembly with the anti-missing identification information of the present invention adopts the following technical solutions: An LC connector assembly with anti-missing identification information, including LC plugs and LC adapters interposed, LC The front end of the plug has a plug-in section that is inserted into the plug-in opening of the LC adapter, and the LC plug is inserted into the LC adapter through the fixed housing of the front end of the plug, and the fixed housing is matched with the side of the LC plug to set the duplex clip. A relief opening on the side that avoids the duplex clamp, avoiding the extension To the rear end surface of the fixed casing, the two side walls of the avoidance opening are provided with a rear end limit step matched with the rear limit of the boss on both sides of the duplex clamp, and the fixed casing is opposite to the side on which the escape opening is provided The printed circuit board is provided on the side of the printed circuit board, and the plug information storage chip is electrically connected to the conductive contact on the printed circuit board, and the LC adapter is connected to the socket. A metal elastic member electrically connected to the conductive contact, the metal elastic member being electrically connected to the signal input end of the system main board.

The surface of the printed board opposite to the fixed housing is coated with strip-shaped gold fingers, and the strip-shaped gold fingers form the conductive contacts, and the metal elastic member is disposed at the plugging mouth and is inserted into the printed board Fitted on the side wall.

The opposite sides of the printed board have positioning notches disposed in pairs, and two of the pair of positioning notches are respectively located on two sides of the printed board, and the fixed shell is fixed on the side wall of the printed board The positioning protrusion is matched with the positioning notch, and the printed board is fixed on the fixed casing by the hot pressing of the positioning protrusion.

The LC plug further has a pressure claw with a free end pressed against the free end of the duplex clamp. The rear end limit step is formed by a front side of the elastic bump disposed on the fixed housing, and the elastic bump passes One end is connected to the side surface of the fixed casing, and the other end of the elastic bump is provided with a lock block that is engaged with the duplex clamp to prevent the duplex clamp from being separated from the pressure claw.

The metal elastic member is fixed on the side wall of the plug-in and the printed board by the small-row insertion force, and the side wall of the plug-in opening and the printed board is provided with a small-sized plug-in. The metal elastic member is a metal elastic needle which is disposed in an angular shape, and one end of the metal elastic needle is inserted through the fixed passage provided by the small row and inserted into the small row plug, and the end of the metal elastic needle is inserted through the small row. The metal clip is electrically connected to the signal input end of the main board of the system, and the other end of the metal elastic needle is slidably disposed in the guiding groove of the side wall of the plug opening and communicating with the through hole, and the portion where the metal elastic needle contacts the printed board is convex. Curved to the printed board.

The through-notch is a stepped notch whose flare is facing outward, the stepped surface of the through-notch is matched with the edge of the inner end surface of the small-row insertion, and the small-row insertion is strongly fixed to the fixed casing by the strong-position positioning column provided at the edge thereof Upper, the guiding groove is at a stepped surface that penetrates the notch.

The LC plug with the anti-missing identification information of the present invention adopts the following technical solutions:

- LC plug with anti-missing identification information, the front end of the LC plug has an LC adapter The plug connector of the plug-in opening is inserted into the LC adapter through the fixed housing of the front end of the LC plug, and the side of the fixed housing and the side of the LC plug with the duplex clip has the avoidance duplex clamp. The avoidance opening extends to the rear end surface of the fixed casing, and the rear side of the avoidance opening is provided with a rear end limit step matched with the rear limit of the boss on both sides of the duplex clamp, the fixed casing and the setting A printed board is disposed on the opposite side of the side surface of the avoidance opening, and the printed board is provided with a plug information storage chip, and the pins of the plug information storage chip are respectively electrically connected to the conductive contacts on the printed board.

The surface of the printed board opposite to the fixed housing is coated with strip-shaped gold fingers, and the strip-shaped gold fingers form the conductive contacts.

The opposite sides of the printed board have positioning notches disposed in pairs, and two of the pair of positioning notches are respectively located on two sides of the printed board, and the fixed shell is fixed on the side wall of the printed board The positioning protrusion is matched with the positioning notch, and the printed board is fixed on the fixed casing by hot pressing welding of the positioning protrusion.

The LC plug further has a pressure claw with a free end pressed against the free end of the duplex clamp. The rear end limit step is formed by a front side of the elastic bump disposed on the fixed housing, and the elastic bump passes The end is connected to the side of the fixed casing, and the other end of the elastic bump is provided with a lock block that is engaged with the duplex clamp to prevent the duplex clamp from being separated from the pressure claw.

The LC plug of the present invention is provided with a plug information storage chip through the printed board, and the two pins of the plug information storage chip are respectively electrically connected with the conductive contacts on the printed board, and the LC adapter is respectively provided with two plugs when plugging The two metal elastic members electrically connected to the conductive contacts, the plug information in the plug information storage chip is input through the signal input end of the system main board through the conductive contact and the metal elastic member, and when the information is matched, the signal output end of the system main board outputs a signal, The indicator that is electrically connected to the signal output end of the system board is on, indicating that the plug is correct. On the contrary, the signal output of the system board does not output a signal, and the indicator does not light. This prevents the problem of interleaving in the presence of two LC connector assemblies with .t:.

DRAWINGS

Figure 1 is a front elevational view of an embodiment of an LC plug of the present invention;

Figure 2 is a plan view of Figure 1; Figure 3 is a bottom view of Figure 1;

Figure 4 is a perspective view of an embodiment of the LC plug of the present invention;

Figure 5 is a front elevational view of the printed board with the plug information storage chip fixed in Figure 1;

Figure 6 is a plan view of Figure 5;

Figure 7 is a bottom view of Figure 5;

Figure 8 is a perspective view of the printed board with the plug information storage chip fixed in Figure 1;

Figure 9 is a front elevational view of the fixed housing of Figure 1;

Figure 10 is a left side view of Figure 9;

Figure 11 is a right side view of Figure 9;

Figure 12 is a plan view of Figure 9;

Figure 13 is a perspective view of the fixed housing of Figure 1;

Figure 14 is a front elevational view of the LC adapter of the LC connector assembly of the present invention;

Figure 15 is a left side view of Figure 14;

Figure 16 is a right side view of Figure 14;

Figure 17 is a bottom view of Figure 14;

Figure 18 is a perspective view of an LC adapter of the LC connector assembly of the present invention;

Figure 19 is a cross-sectional view of the LC adapter of the LC connector assembly of the present invention at a central symmetry plane; Figure 20 is a cross-sectional view of the LC adapter of the LC connector assembly of the present invention at the metallized bullet; Figure 21 is an LC of the present invention; Schematic diagram of the structure of the connector assembly before assembly;

Figure 22 is a perspective view showing the assembled structure of the LC connector assembly of the present invention before being integrally assembled; Figure 23 is a front view of the empty adapter of the LC adapter and the conventional LC plug in the LC adapter;

Figure 24 is a left side view of Figure 23;

Figure 25 is a right side view of Figure 23;

Figure 26 is a plan view of Figure 23;

Figure 27 is a bottom view of Figure 23; Figure 28 is a perspective view of the empty adapter of the LC adapter mated with the conventional LC plug in the LC adapter.

detailed description

An embodiment of an LC connector assembly having an anti-missing identification information, the LC connector assembly including an LC plug and an LC adapter, as shown in FIGS. 1 to 13, the front end of the LC plug 1 is provided with a fixed casing The body 4, the fixed housing 4, and the side of the fixed housing 4 that cooperates with the side surface of the LC plug provided with the duplex clip 5 has a relief opening 23 for avoiding the duplex clip 5, avoiding the opening of the opening 23 toward the rear end and extending to the fixed On the rear end surface of the casing 4, the front side of the escape opening 23 is blocked at the front of the duplex clamp 5. A rear limit step 13 is disposed at a side wall of the avoidance opening 23 on both sides of the duplex clip 5, and the rear limit step 13 cooperates with the boss limit on both sides of the duplex clip 5, when the fixed housing is opposite to the LC plug When moving forward, the rear limit step 13 will contact the boss 10 on both sides of the duplex clip, and the fixed housing will not continue to move relative to the LC plug, preventing the fixed housing from being removed from the LC plug. , to ensure that the fixed housing 4 is always placed on the LC plug when in use.

The LC plug is provided with a pressure claw 15, one end of the pressure claw 15 is integrally fixed on the LC plug, and the other end is suspended, and the free end of the pressure claw 15 is pressed on the free end of the duplex clamp 5, when working When the LC plug needs to be separated from the LC adapter, the jaws 15 are depressed, the jaws 15 will apply pressure to the duplex clamp 5, and the LC plug is separated from the LC adapter, as is the case with prior art separations. The rear limit step 13 is a front side of the elastic projection 17 provided on the fixed casing, and the two elastic projections 17 are respectively located on both sides of the duplex clamp 5. One end of the elastic protrusion 17 is integrally connected with the side surface of the fixed casing, and the other ends of the two elastic protrusions 17 are respectively provided with oppositely extending locking blocks 11 respectively, and the two locking blocks 11 respectively and the two sides of the duplex clamp 5 The card is arranged to prevent the duplex clamp 5 from being separated from the pressure claw 15. This prevents the LC plug and LC adapter from being unlocked because the free end of the duplex clamp moves over the jaws.

The fixed housing 4 is provided with a recessed surface on a side opposite to the side on which the escape opening is provided. The recessed portion is provided with a printed board 2, and the printed board 2 is in close contact with the groove bottom on which the recess is provided. The plug information storage chip 6 is fixed on the surface of the printed board 2 which is matched with the groove bottom provided with the groove, and the groove bottom of the groove is provided with a square space 14 for accommodating the plug information storage chip 6, and the plug information storage chip 6 is fitted and fitted. Square empty In the space 14, the surface of the printed board 2 opposite to the groove bottom of the groove is coated with two strip-shaped gold fingers 3, and the pins of the plug information storage chip 6 are electrically connected to the two gold fingers 3, respectively. The opposite sides of the printed board 2 have two pairs of semi-cylindrical positioning notches 21, one of which is on one side of the printed board 2 and the other on the other side of the printed board 2. Correspondingly, a semi-cylindrical positioning post 16 is formed at the groove wall of the groove, and the positioning post 16 extends out of the outer surface of the printed board 2, and is assembled by thermocompression bonding during assembly. The portion of the positioning stud extending beyond the surface of the printed board is deformed to fix the printed board 2 on the fixed housing 4. A dust cover 12 is sleeved on the front end of the fixed casing 4.

As shown in FIG. 14 to 20, the two ends of the LC adapter 7 are provided with a plug-in opening for accommodating the front end of the LC plug. The two plug-in openings and the plug-in opening have the same structure, and can be considered as having two identical connectors. They are integrally placed together at the respective non-open ends. A through hole is formed in a side wall of the plug-in opening which is matched with the printed board 2 when the plug-in opening is inserted, and the through-notch is a stepped notch which is flared outward, and the small-sized plug 20 is smallly fitted on the through-cut notch. The socket 20 is plate-shaped. The edge of the end face of the small row insert 20 is engaged with the stepped surface that penetrates the notch. Two metal elastic pins 9 are disposed on the inner end surface of the small row insert 20, and the metal elastic needles 9 are disposed in an angular shape, and one end of the metal elastic needle 9 is inserted into the fixed passage provided on the small row insert 20 and inserted by the small row. The outer end surface of the outer end surface 20 is pierced, and the metal elastic needle 9 is fixed to the small row insertion hole 20 by the cooperation with the fixed passage. The end of the metal elastic pin 9 penetrating the outer end surface of the small row plug 20 is provided as a pin, and the pin is electrically connected to the signal input end of the system main board, and transmits the signal input chip from the plug information storage chip to the signal input end of the system main board. Information, set the LC adapter in the system. The other end of the metal bullet 9 is freely overhanging toward the inner end of the insertion opening. A guide groove communicating with the through-notch is provided in the side wall of the insertion opening at the stepped surface of the through-notch, and one end of the free overhang of the metal elastic needle 9 is slidably disposed in the guide groove. When the LC plug is plugged into the LC adapter, the gold finger on the printed board will squeeze the metal bullet. The free end of the metal bullet will slide in the guiding slot of the plug opening. The angle of the metal bullet becomes larger, the metal The pin will eventually be pressed into the guiding slot to achieve the final insertion of the LC plug and the LC socket. The contact between the metal pin and the printed board is curved toward the printed board, so that even the length of the metal pin When it is short, it can also ensure reliable contact with the printed board. This arrangement of metal bullets is readily understood by those skilled in the art and is also readily accomplished. An LED indicator is provided on the system board, and the pin of the LED indicator is used for outputting with the system board. Electrical connection, when the correct LC plug is plugged into the LC adapter, the LED lights up, otherwise it does not light.

The small row plug 20 is provided with a fixing protrusion near the edge of the inner end of the insertion opening, and the fixing protrusion is provided with an inwardly extending strong positioning positioning column 22, and the side wall of the insertion opening is provided with the strong positioning positioning column. The positioning hole is strongly installed in the positioning hole to fix the small row plug 20 to the fixed housing. A protruding fixing head is disposed on two side walls of the edge of the small row plug 20, and a fixing notch strongly matched with the fixing head is disposed on the side wall of the through hole, and the fixing head and the fixing notch are strongly assembled and combined. The strong positioning of the positioning post and the positioning hole fixes the small row plug on the fixed housing.

A fixing post 8 is integrally provided on the side of the LC adapter 7 on which the small row is inserted. The fixing post 8 is used to fix the LC adapter to the panel of the system. When assembling, the mounting hole is arranged on the panel of the system, and the fixing post 8 is arranged. The LC adapter is fixed in the panel of the system by being inserted into the mounting hole and then deforming the end of the fixing post 8 by thermal deformation.

An embodiment of an LC plug having mis-insertion identification information, which is the LC plug of Figures 1 to 13 above. An important feature of the LC plug is that a chip storing plug information is disposed on the plug. When the LC plug and the adapted LC adapter are plugged in, the information in the plug information storage chip passes through the strip of gold fingers of the printed board. The metal bullet is transmitted to the system board, and the system board analyzes the plug information to determine if the plug is plugged into the correct LC adapter.

The plug information storage chip of the above embodiment is disposed on the surface of the printed board and the connecting board, or may be disposed on the other surface of the printed board. At this time, the plug information storage chip may be disposed at the rear of the printed board. A strip of gold fingers is placed at the front.

In the above embodiment, the metal elastic needle of the LC adapter is fixed on the side wall of the insertion opening through a small row of inserts, and one end of the metal elastic needle may be directly fixed on the side wall of the open groove by welding or clamping. Then, the wires or the conductive strips are electrically connected to the fixed ends of the metal pins, and the wires or the conductive strips are embedded on the side walls of the open slots.

In the above embodiment, the metal elastic member of the LC adapter is a metal elastic needle, and may be a metal elastic piece whose one end is fixed on the side wall of the insertion opening and the other end is inwardly suspended.

The printed board of the above embodiment is fixed to the LC plug by a fixed housing, or may be bonded The way is fixed directly on the side of the LC plug.

The indicator of the above embodiment is an LED indicator. Of course, the indicator can also be other types of indicators.

The LED indicator in the above embodiment is set in the system 屮, or it can be directly set on the LC adapter, and the LED indicator is connected to the circuit of the system.

The information that can be stored in the plug information storage chip in the above embodiment may be a signal that uniquely identifies the plug identity, such as the number of the plug. The signals carried by the plugs are different, allowing the system to recognize different plugs and prevent the plugs from being plugged into the mismatched adapter. Of course, the plug information storage chip can also store other information about the plug, such as: the signal transmitted by the plug, the type of the cable connected to the plug, the number of fiber ends, and the like.

21 and FIG. 22, when information recognition is not required, an empty converter 18 as shown in FIGS. 23 to 28, a portion where the air converter 18 is engaged with the LC adapter, and a structure of the fixed casing may be disposed in the LC adapter. Similarly, the difference between the two is that a side end of the LC plug of the empty converter 18 on which the duplex clip is disposed is provided with a claw 19 which is integrally provided at one end of the side of the empty converter and freely overhangs at the other end. The claw 19 is provided with the same snap-fit structure as the duplex clip for engaging with the LC adapter. In use, the claw 19 fixes the empty converter in the LC adapter, and the ordinary LC plug is inserted in the The insertion of the LC adapter can be realized in the empty converter. At the end of the freely overhanging of the claw 19, there is a step surface which cooperates with the boss of the duplex clamp of the ordinary LC plug, and the empty converter passes through the stepped surface and the space The front side of the converter's escape port places the normal LC plug in the empty converter. Therefore, it can be interchanged with a conventional LC plug without changing the way the LC plug and adapter are connected. When there is no chip, you only need to install an empty converter in the adapter to connect with the standard LC plug. The flat-time converter is installed in the adapter. When the LC plug is not pulled out, the empty converter cannot be removed. Only the LC plug is pulled out. Then you can remove the empty converter. It can also be known from this point that when information recognition is required, it is only necessary to provide a fixed housing with a printed board on a conventional LC plug to cooperate with an LC adapter having a metal elastic needle to realize information recognition, that is, There is no need to customize a special LC plug, only a normal LC plug is required, and the LC plug and the fixed housing can be replaced independently, and no overall replacement is required in case of damage.

Claims

Claim

An LC connector assembly with mis-insertion identification information, comprising an LC plug and an LC adapter interposed therebetween, the front end of the LC plug having a plug-in section interposed with the plug-in opening of the LC adapter, characterized in that: The LC plug is inserted into the LC adapter through a fixed housing that is sleeved at the front end thereof, and the side of the fixed housing and the side of the LC plug with the duplex clip has an escape opening for avoiding the duplex clip, and the escape opening extends to the fixed housing. On the rear end surface, the two side walls of the avoidance opening are provided with a rear end limit step which cooperates with the rear limit of the boss on both sides of the duplex clip, and the side of the fixed housing opposite to the side on which the cutout is disposed is arranged The printed board is provided on the printed board, and the plug information storage chip is arranged on the printed board. The pins of the plug information storage chip are respectively electrically connected to the conductive contacts on the printed board, and the LC adapter is respectively provided with the plugging A metal elastic member electrically connected to the conductive contact, the metal elastic member being electrically connected to the signal input end of the system main board.

2. The LC connector assembly with anti-missing identification information according to claim 1, wherein: the surface of the printed board opposite to the fixed housing is coated with a strip of gold fingers, strip gold The finger forms the conductive contact, and the metal elastic member is disposed on the sidewall of the plug-in opening and the printed board.

3. The LC connector assembly with anti-missing identification information according to claim 2, wherein: opposite sides of the printed board have positioning recesses disposed in pairs, and two of the pair of positioning notches The positioning notches are respectively located on two sides of the printed board, and the side walls of the fixed printed board are provided with positioning protrusions corresponding to the positioning notches, and the printed boards are fixed by fixing by the positioning protrusions. Carcass ten.

4. The LC connector assembly with anti-missing identification information according to claim 1 or 2 or 3, wherein: said LC plug further has a claw on which the free end is pressed against the free end of the duplex clip. The rear end limit step is formed by a front side surface of the elastic bump disposed on the fixed casing, the elastic bump is connected to the side of the fixed casing through one end, and the other end of the elastic bump is provided with the duplex clamp The card is provided with a lock block that prevents the duplex clip from coming off the claw.

5 . The LC connector assembly with anti-missing identification information according to claim 1 , wherein: the metal elastic member is fixed to the side of the plug-in connector and the printed board by a small row of plugs. On the wall, the side wall of the plug-in opening and the printed board are mated with a through-notch for assembling a small row of inserts, the metal elastic member is a metal bullet provided with an angle, and one end of the metal bullet passes through the small row The fixed passage that is inserted is disposed on the small row of inserts, and one end of the metal elastic needle that is inserted out of the small row is electrically connected to the signal input end of the system main board, and the other end of the metal elastic needle is slidably disposed on the side of the plugged opening In the guiding groove formed in the wall and communicating with the through-notch, the portion where the metal elastic needle contacts the printed board is an arc convex toward the printed board.

6 . The LC connector assembly with anti-missing identification information according to claim 5 , wherein: the through-notch is a stepped notch whose flare is outward, and the stepped surface of the through-hole and the inside of the small-row plug are inserted. The edge of the end face is matched, and the small row insert is strongly fixed to the fixed casing through the strong positioning positioning column disposed at the edge thereof, and the guiding groove is located at the stepped surface of the through hole.

7. An LC plug with anti-missing identification information, the front end of the LC plug has a plug-in section that is inserted into the plug-in opening of the LC adapter, and is characterized in that: the LC plug is fixedly mounted by a front end of the LC plug. The LC adapter is inserted, and the side surface of the fixed housing and the LC plug provided with the duplex clip has a relief opening for avoiding the duplex clamp, and the avoidance opening extends to the rear end surface of the fixed housing to avoid the two side walls of the cutout The rear end limit step is matched with the rear limit of the boss on both sides of the duplex clip, and the fixed shell is fixedly attached with the printed board on the side opposite to the side on which the cutout is disposed, and the printed board is provided There is a plug information storage chip, and the pins of the plug information storage chip are respectively electrically connected to the conductive contacts on the printed board.

8 . The LC connector set plug with anti-missing identification information according to claim 7 , wherein: the surface of the printed board opposite to the fixed housing is coated with a strip of gold fingers, strips A gold finger forms the conductive contact.

9. The LC plug with anti-missing identification information according to claim 8, wherein: opposite sides of the printed board have positioning notches disposed in pairs, and two positioning gaps in a pair of positioning notches Separately located on the two sides of the printed board, the side wall of the fixed printed circuit board is provided with a positioning protrusion corresponding to the positioning notch, and the printed board is fixed to the fixed shell by hot pressing of the positioning protrusion on. The LC plug with anti-missing identification information according to claim 7 or 8 or 9, wherein: the LC plug further has a pressure claw with a free end pressed against the free end of the duplex clamp, The rear limit step is formed by a front side of the elastic bump disposed on the fixed casing, and the elastic bump is connected to the side of the fixed casing through one end, and the other end of the elastic bump is provided with the duplex clamp to prevent double A lock block that is separated from the jaws.