CA1037554A - Line surge protecting device for telephone lines - Google Patents
Line surge protecting device for telephone linesInfo
- Publication number
- CA1037554A CA1037554A CA209,975A CA209975A CA1037554A CA 1037554 A CA1037554 A CA 1037554A CA 209975 A CA209975 A CA 209975A CA 1037554 A CA1037554 A CA 1037554A
- Authority
- CA
- Canada
- Prior art keywords
- gaseous discharge
- temperature sensitive
- sensitive element
- soldered
- cavity
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Emergency Protection Circuit Devices (AREA)
- Fuses (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A line voltage surge protecting device for telephone system which normally include means for grounding excessive currents caused by lightning and the like. The device includes a gaseous discharge element which becomes conductive when the voltage in the line being protected momentarily exceeds a pre-determined value to conduct current to a source of ground potential.
A temperature sensitive element responsive to heat generated by the gaseous discharge element during prolonged excessive current serves to short the gaseous discharge element to ground. The temperature sensitive element includes means resiliently biasing the gaseous element for movement serving to short the same. A
soldered retaining means opposes such movement, and beat developed in the gaseous discharge device is transmitted to the soldered means by conduction to melt the solder to permit the shorting action to occur. The protective structure is disposed in a casing element having improved cover means facilitating accessibility for repair and resetting of the soldered means.
A line voltage surge protecting device for telephone system which normally include means for grounding excessive currents caused by lightning and the like. The device includes a gaseous discharge element which becomes conductive when the voltage in the line being protected momentarily exceeds a pre-determined value to conduct current to a source of ground potential.
A temperature sensitive element responsive to heat generated by the gaseous discharge element during prolonged excessive current serves to short the gaseous discharge element to ground. The temperature sensitive element includes means resiliently biasing the gaseous element for movement serving to short the same. A
soldered retaining means opposes such movement, and beat developed in the gaseous discharge device is transmitted to the soldered means by conduction to melt the solder to permit the shorting action to occur. The protective structure is disposed in a casing element having improved cover means facilitating accessibility for repair and resetting of the soldered means.
Description
~L03~55~ ~
BACKG~OUND OF THE INVFNTION
This invention relates generally to the field of electrical pr~tective devices, and more particularly to a device for temporarily grounding a telephone line, portions of which have been struck by lightning, or which suddenly receive a surge of excessive current caused by an increase in voltage . Pevices of this general type are known in the art, and the invention lies in speciic constructional de-tails which permit improved ease of manufacture, at lowered -~ 10 cost, the posqibility of repair of the devices for reuse, and improved reliability.
It is kn~wn in the art to provide means for selectively grounding telephone lines during the period of excessive surges ; of current~ While this action temporarily renders the line " inoperative, it sa~es the occurren~e of permanent damage to the line, with the corresponding requirement o repair. It is known in the art to provide devices which provide a tem-porary grounding effect for surges of relatively short -duration, and a ~use type device which must be manually reset ~:~ 20 in the cases o~ surges of longer duration. Prior art devices,' however, have been relatively expensive, both in the manufacture of the same and the relatively high replacement rate during normal operakion, since once the fused element has been blown, `
it is not possible to reuse the device.
~RIEF DESCRIPTION OF THE PRESENT INV~TIOl~
Brie~ly stated, the invention contemplates the provision of a device of the class described in which heat ~-; developed in a gaseous discharge device is directly conducted to a soldered retaining means without the use of a resistive . .
;,'.. . : .: . ~ , . . , - ~, ...................... . .
.: :~ . . . . . ...
~3375~9~
heat coil for faster operation. ~ casing element having a detachable cover is provided, the removal of whi~l requlres a tool to release internally disposed latching means maintaining the cover in engaged condition.
BR IEF DESCRIPTION OF THE DRAWI~GS
In the drawings, to which reference will be made in the specification, similar reference charactars have been employed to designate corresponding parts throughout the -several views.
Figure 1 is a view in elevation of a first embodiment o the i~vention.
Figure 2 is an enlarged fragmentary sectional view of the first embodiment, partly in elevation and showing the opening of a casing element thereof by removal of an end cap.
. . .
Figure 3 is a longitudinal central sectional view of ~ ~ -the first embodiment.
Figure 4 is a view in perspective, partially in section of the first er~bodiment.
Figure 5 is a longitudinal central sectional vi~w of a second embodiment of the invention, as seen from the plane 5-5 in ~igure 6. ~ ;~
Figure 6 is a central sectional view of the second embodimentt as seen from the plana6-6 in Figure 5.
Figure 7 is a schematic electrical wiring diagram`~
sh~wing the interconnection of the second embodiment in a telephone line system.
VEl~AILE:D DESCRIPTION OF_THE DISCLOSE:D EUIIO IME~TS
~n accordance with the first embodiment of the invention, the device, generally indicated by refarence -~
'"' ~ ''
BACKG~OUND OF THE INVFNTION
This invention relates generally to the field of electrical pr~tective devices, and more particularly to a device for temporarily grounding a telephone line, portions of which have been struck by lightning, or which suddenly receive a surge of excessive current caused by an increase in voltage . Pevices of this general type are known in the art, and the invention lies in speciic constructional de-tails which permit improved ease of manufacture, at lowered -~ 10 cost, the posqibility of repair of the devices for reuse, and improved reliability.
It is kn~wn in the art to provide means for selectively grounding telephone lines during the period of excessive surges ; of current~ While this action temporarily renders the line " inoperative, it sa~es the occurren~e of permanent damage to the line, with the corresponding requirement o repair. It is known in the art to provide devices which provide a tem-porary grounding effect for surges of relatively short -duration, and a ~use type device which must be manually reset ~:~ 20 in the cases o~ surges of longer duration. Prior art devices,' however, have been relatively expensive, both in the manufacture of the same and the relatively high replacement rate during normal operakion, since once the fused element has been blown, `
it is not possible to reuse the device.
~RIEF DESCRIPTION OF THE PRESENT INV~TIOl~
Brie~ly stated, the invention contemplates the provision of a device of the class described in which heat ~-; developed in a gaseous discharge device is directly conducted to a soldered retaining means without the use of a resistive . .
;,'.. . : .: . ~ , . . , - ~, ...................... . .
.: :~ . . . . . ...
~3375~9~
heat coil for faster operation. ~ casing element having a detachable cover is provided, the removal of whi~l requlres a tool to release internally disposed latching means maintaining the cover in engaged condition.
BR IEF DESCRIPTION OF THE DRAWI~GS
In the drawings, to which reference will be made in the specification, similar reference charactars have been employed to designate corresponding parts throughout the -several views.
Figure 1 is a view in elevation of a first embodiment o the i~vention.
Figure 2 is an enlarged fragmentary sectional view of the first embodiment, partly in elevation and showing the opening of a casing element thereof by removal of an end cap.
. . .
Figure 3 is a longitudinal central sectional view of ~ ~ -the first embodiment.
Figure 4 is a view in perspective, partially in section of the first er~bodiment.
Figure 5 is a longitudinal central sectional vi~w of a second embodiment of the invention, as seen from the plane 5-5 in ~igure 6. ~ ;~
Figure 6 is a central sectional view of the second embodimentt as seen from the plana6-6 in Figure 5.
Figure 7 is a schematic electrical wiring diagram`~
sh~wing the interconnection of the second embodiment in a telephone line system.
VEl~AILE:D DESCRIPTION OF_THE DISCLOSE:D EUIIO IME~TS
~n accordance with the first embodiment of the invention, the device, generally indicated by refarence -~
'"' ~ ''
- 2 -'.'~ ,.: :
" ~37SS~
character 210, comprises, broadly: a housing or casing element 211, a grounding prong element 212, circuit connecting means 213, and temperature sensitive current grounding means 214.
~ ~ ' :, ' !
The casing element 211 i5 preferably formed from-synthetic resinous materials, and includes a main body 216 bounded by side walls 217 and 218, an upper wall 219, and a lower wall 220. A separable cover 221 includes a manually- -~
engageable grip 222 extending longitudinally from an oppositely disposed end wall 223. A plurality of flange members 224 interfit with a corresponding plurality of interstices 225 on the main body, as best seen in Figure 1, and the cover 221 is maintained on the main body 216 by the engagement of flexible tabs 226 on the body within corresponding openings . .
227 on the centrally disposed flange members 228 ~see Figure 2 ~i The tabs 226 are cammed outwardly as shown in Figure 2 by cam surfaces 228 on the cover and deten~: portions 229 engaging openings 227 when the cover is fuLly seated. The wall 223 is provided with openings 231 which permit the intentional and authorized removal of the cover 221 with respect to the body 216 for repair. This is accomplished by a tool element 236 having -a body 237 from which extend a plurality of longitudinally projec~ing members 238. These members are inserted into the openings 231 and are provided with camming surfaces 233 also capable of spreading the flange members on the body as shown in ~igure 2, permitting the cover and tool element to be a withdrawn simultaneously. Since the detent means which ~`
maintains the cnver in association with the body are otherwise inaccessible, unauthorized opening of the device without ; damage is v~rtually impossible. ` -'~
" ~37SS~
character 210, comprises, broadly: a housing or casing element 211, a grounding prong element 212, circuit connecting means 213, and temperature sensitive current grounding means 214.
~ ~ ' :, ' !
The casing element 211 i5 preferably formed from-synthetic resinous materials, and includes a main body 216 bounded by side walls 217 and 218, an upper wall 219, and a lower wall 220. A separable cover 221 includes a manually- -~
engageable grip 222 extending longitudinally from an oppositely disposed end wall 223. A plurality of flange members 224 interfit with a corresponding plurality of interstices 225 on the main body, as best seen in Figure 1, and the cover 221 is maintained on the main body 216 by the engagement of flexible tabs 226 on the body within corresponding openings . .
227 on the centrally disposed flange members 228 ~see Figure 2 ~i The tabs 226 are cammed outwardly as shown in Figure 2 by cam surfaces 228 on the cover and deten~: portions 229 engaging openings 227 when the cover is fuLly seated. The wall 223 is provided with openings 231 which permit the intentional and authorized removal of the cover 221 with respect to the body 216 for repair. This is accomplished by a tool element 236 having -a body 237 from which extend a plurality of longitudinally projec~ing members 238. These members are inserted into the openings 231 and are provided with camming surfaces 233 also capable of spreading the flange members on the body as shown in ~igure 2, permitting the cover and tool element to be a withdrawn simultaneously. Since the detent means which ~`
maintains the cnver in association with the body are otherwise inaccessible, unauthorized opening of the device without ; damage is v~rtually impossible. ` -'~
- 3 - ;~
, ` ~)3~5~ ~
The grounding prong element 212 includ~s a supporting sleeve 240 surrounding a metallic prong 241 which extends rearwardly to contac-t a metallic plate 242 f~rming part of the circuit connecting means 213.
The circuit connecting means 213 includes a pair of tip contacts 244 and 245, as well as a pair of ring contacts 246 and 247, as is wPll known in the art. A conductive strip 248 connects the contact 247 to the winding of a heat coil 249, and current is connected back through the heat coil spxing 250. A
similar duplication of structure, not shown, interconnects the tip ~ontacts 244 and 245.
The grounding means 214 are two in number, only one being illustrated in Figures 3 and 4. Each includes the above mentioned spring 250 which acts upon a spring follower 254 supporting a centrally positioned contact mem~er 255. The inner end 256 thereof is positioned in a socket 257 in the follower 254.
The outer end 258 is pointed and adapted when the circuit `
grounding mPans 214 is actuated to make contact with the plate 242 whereby at least one circuit is grounded to the prong element 212.
This p~sition is illustrated in Figure 4~
~ omentary fluctuations in current will not normally actuate the temperature sensitive grounding means 214, and such surges are accommodated by the gaseous discharge device 25g in well known manner~ Current in this case flows from the contact `
246 to member 260, to the surface 261 of the gaseous discharge device, and from the surface 262 to the plate 242 and thence to ground. Once actuated9 the gaseous discharge device is bypassed, and the current flows directly to ground.
It will be observed that removal of the cover 2
, ` ~)3~5~ ~
The grounding prong element 212 includ~s a supporting sleeve 240 surrounding a metallic prong 241 which extends rearwardly to contac-t a metallic plate 242 f~rming part of the circuit connecting means 213.
The circuit connecting means 213 includes a pair of tip contacts 244 and 245, as well as a pair of ring contacts 246 and 247, as is wPll known in the art. A conductive strip 248 connects the contact 247 to the winding of a heat coil 249, and current is connected back through the heat coil spxing 250. A
similar duplication of structure, not shown, interconnects the tip ~ontacts 244 and 245.
The grounding means 214 are two in number, only one being illustrated in Figures 3 and 4. Each includes the above mentioned spring 250 which acts upon a spring follower 254 supporting a centrally positioned contact mem~er 255. The inner end 256 thereof is positioned in a socket 257 in the follower 254.
The outer end 258 is pointed and adapted when the circuit `
grounding mPans 214 is actuated to make contact with the plate 242 whereby at least one circuit is grounded to the prong element 212.
This p~sition is illustrated in Figure 4~
~ omentary fluctuations in current will not normally actuate the temperature sensitive grounding means 214, and such surges are accommodated by the gaseous discharge device 25g in well known manner~ Current in this case flows from the contact `
246 to member 260, to the surface 261 of the gaseous discharge device, and from the surface 262 to the plate 242 and thence to ground. Once actuated9 the gaseous discharge device is bypassed, and the current flows directly to ground.
It will be observed that removal of the cover 2
- 4 -s~
permits all of the above describecl structure to be removed ~rom the body fQr servicing and/or replac~ment, without the use of special tools, other than the above descri~ed tool element 236.
Turning now to the second embodiment of the invention, illustrated in Figures 5, 6 and 7~ the device, generally indicated by reference charact~r 270, includes a casing element 271 generally similar to that in the first embodiment, a plurality o~ input terminals, one of which is indicated by re~erence character 272, a plurality of output terminals 273, a grounding prong element 274 and a cover 275 engaged and - ~
disengaged with respect to the casing element 271 as in the ~ ~-;~:
first embodiment~ The second embodiment differs from the first embodiment principally in structure which permits not , . . .
only the shunting o~ excess current surges to ground, but the actual opening of the telephone circuits upon the occurrence .
o a sustained overload. Referring to Figure 7, there is `I illustrated a schematic diagram sh~wing the operation of the second embodLment.
~s in the f i rst embo~ment, the device i~ adapted ~o bridge~a pair o~ input 278 and 279 and a pair of outputs 280 and 281. Unlike prior ar devices, by the use of the second e~bodiment 270, there are provided a pair of switches 282 and 283 which, upon the occurrence of a sustained overload, open to protect the output circuits 280 and ~81 until the device is ~ither reset or replaaed. The device 270 incorporates a known and recently developed three element gaseous discharge tube 284 which at all times communicates with the grounding p~ong -~
element 285, and which, as a result of relative motion between
permits all of the above describecl structure to be removed ~rom the body fQr servicing and/or replac~ment, without the use of special tools, other than the above descri~ed tool element 236.
Turning now to the second embodiment of the invention, illustrated in Figures 5, 6 and 7~ the device, generally indicated by reference charact~r 270, includes a casing element 271 generally similar to that in the first embodiment, a plurality o~ input terminals, one of which is indicated by re~erence character 272, a plurality of output terminals 273, a grounding prong element 274 and a cover 275 engaged and - ~
disengaged with respect to the casing element 271 as in the ~ ~-;~:
first embodiment~ The second embodiment differs from the first embodiment principally in structure which permits not , . . .
only the shunting o~ excess current surges to ground, but the actual opening of the telephone circuits upon the occurrence .
o a sustained overload. Referring to Figure 7, there is `I illustrated a schematic diagram sh~wing the operation of the second embodLment.
~s in the f i rst embo~ment, the device i~ adapted ~o bridge~a pair o~ input 278 and 279 and a pair of outputs 280 and 281. Unlike prior ar devices, by the use of the second e~bodiment 270, there are provided a pair of switches 282 and 283 which, upon the occurrence of a sustained overload, open to protect the output circuits 280 and ~81 until the device is ~ither reset or replaaed. The device 270 incorporates a known and recently developed three element gaseous discharge tube 284 which at all times communicates with the grounding p~ong -~
element 285, and which, as a result of relative motion between
- 5 -: ,- . .
:, :
lt and the casing element, closes switches 286 and 287 upon the occurrence of sustained overload to permit the gaseous discharge device to be discharged to ground.
Referring to Figures 5 and 6, there is illustrated - the structure corresponding to Figure 7. A fixed spring ~ :
anchor 291 is mounted on a wall of the cavity formed in the casing element 271, the same mounting a coil spring 292 sup-porting on an opposite end a movable follower 293. The outer suxface 294 of the followex is curved and corresponds in configuration to the outer surface 295 of the gaseous discharge device 284. In the position shown in Figure 5, the device 284 contacts the curved surface 296 o a stop member 297 which forms part of the grounding prong element 285. Prior to activation, the device 284 is maintained in the position shown in Figure 6 ;~
against the tension of the spring 292 by a thermally t conductive stop rod 298, the inner end 299 of which contacts the surface 295, and the outer end 300 of which is disposed ;-t, with a bore 301 in the memiber 297. Reference character 302 -,, :
` indicates a point at which the rod 298 is soldered to the 20 surface 296~
rhe end surfaces 303 and 304 of the device 284 communicate with :E~rSt and second conductive strips 305 and . . -, ~ 306, respectiveïy, at outer ends 307 thereof. The inner ends .~ . 308 thereof are inwardly bent and communicate with mounted contacts 309 each of which is adapted to engage the inner ends ;:
310 of the terminals 272 and 273 when the device is in the ~: condition indicated in Figure 6. ;~ ~
During normal operation, the devica will remain in ~:
this condition, the engagement of the contacts 306 with the -: ~ -- 6 --755~
ends 310 providing the equivalent of closing the switche~ 2~2 and 283 in Figure 7. Upon the occurrence of a momentary over-load, the device 284 will become ionized, and discharged to ground through the centrally disposed conductor 313 in Figure 7, in this condition, the switches 286 and 287 being opened.
Should a sustained overload occur, the gaseous discharge device 284 will not only ionize, but will become heated, the heat be mg conducted down the rod 298 to melt the ~ solder 302, and allow the rod 298 to move outwardly in the ;- 10 bore 301 wherein it projects outwardly of the cover 275 to give a visual indication of the condition of the device 270.
... . .
This movement moves the device 284 into direct contact with the member 297 and performs the e~uivalent of closing the ( switches 286 and 287 and discharging whatever charge remains ; on the device 284 at that time. A~ the spring 292 expands and moves the device 284, the strips 305 and 306 move with the ~`~ device 284~ thereby causing the contacts 109 to part contact . ~
wi~h the inner ends 310 of the terminals 272 and 273, thereby ~`
l opening the circuit being protected.
;~ ~ 20 The setting of the device 270, assuming no damage to the device 284, requires only the removal of the cover 275 and ~ ;
the resoldering of the stop rod 298 to its original position ;~
shown in Figure 6, following which the cover 275 is replaced in engagement with the casing element 271. "
;1~ It is to be understood that it is not considered ~
:
that the invention is limited to the specific details of ~
structure shown and described herein, for obvious modifications ~ ;
: ~ -will occur to those ~killed in the art to which the invention pertains.
~. , ,', ~ ,
:, :
lt and the casing element, closes switches 286 and 287 upon the occurrence of sustained overload to permit the gaseous discharge device to be discharged to ground.
Referring to Figures 5 and 6, there is illustrated - the structure corresponding to Figure 7. A fixed spring ~ :
anchor 291 is mounted on a wall of the cavity formed in the casing element 271, the same mounting a coil spring 292 sup-porting on an opposite end a movable follower 293. The outer suxface 294 of the followex is curved and corresponds in configuration to the outer surface 295 of the gaseous discharge device 284. In the position shown in Figure 5, the device 284 contacts the curved surface 296 o a stop member 297 which forms part of the grounding prong element 285. Prior to activation, the device 284 is maintained in the position shown in Figure 6 ;~
against the tension of the spring 292 by a thermally t conductive stop rod 298, the inner end 299 of which contacts the surface 295, and the outer end 300 of which is disposed ;-t, with a bore 301 in the memiber 297. Reference character 302 -,, :
` indicates a point at which the rod 298 is soldered to the 20 surface 296~
rhe end surfaces 303 and 304 of the device 284 communicate with :E~rSt and second conductive strips 305 and . . -, ~ 306, respectiveïy, at outer ends 307 thereof. The inner ends .~ . 308 thereof are inwardly bent and communicate with mounted contacts 309 each of which is adapted to engage the inner ends ;:
310 of the terminals 272 and 273 when the device is in the ~: condition indicated in Figure 6. ;~ ~
During normal operation, the devica will remain in ~:
this condition, the engagement of the contacts 306 with the -: ~ -- 6 --755~
ends 310 providing the equivalent of closing the switche~ 2~2 and 283 in Figure 7. Upon the occurrence of a momentary over-load, the device 284 will become ionized, and discharged to ground through the centrally disposed conductor 313 in Figure 7, in this condition, the switches 286 and 287 being opened.
Should a sustained overload occur, the gaseous discharge device 284 will not only ionize, but will become heated, the heat be mg conducted down the rod 298 to melt the ~ solder 302, and allow the rod 298 to move outwardly in the ;- 10 bore 301 wherein it projects outwardly of the cover 275 to give a visual indication of the condition of the device 270.
... . .
This movement moves the device 284 into direct contact with the member 297 and performs the e~uivalent of closing the ( switches 286 and 287 and discharging whatever charge remains ; on the device 284 at that time. A~ the spring 292 expands and moves the device 284, the strips 305 and 306 move with the ~`~ device 284~ thereby causing the contacts 109 to part contact . ~
wi~h the inner ends 310 of the terminals 272 and 273, thereby ~`
l opening the circuit being protected.
;~ ~ 20 The setting of the device 270, assuming no damage to the device 284, requires only the removal of the cover 275 and ~ ;
the resoldering of the stop rod 298 to its original position ;~
shown in Figure 6, following which the cover 275 is replaced in engagement with the casing element 271. "
;1~ It is to be understood that it is not considered ~
:
that the invention is limited to the specific details of ~
structure shown and described herein, for obvious modifications ~ ;
: ~ -will occur to those ~killed in the art to which the invention pertains.
~. , ,', ~ ,
Claims
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS
1. An improved telephone line surge protecting device comprising: a casing element defining a cavity, telephone input and output terminals having inner ends communicating with said cavity, a grounding prong element penetrating said casing element and communicating with said cavity, a temperature sensitive element mounted for sliding movement between first and second positions within said cavity, resilient means urging said temperature sensitive element from said first to said second position, temperature sensitive means resisting said resilient means; said temperature sensitive element including a gaseous discharge device and electrically conductive members communicating with said gaseous discharge device substantially at one end thereof, and having second ends communicating with at least one of said input and output terminals when said temperature sensitive element is in said first position; said temperature sensitive element upon moving from said first position to said second position breaking communi-cation of said conductive members with said input and output terminals, and establishing communication between said gaseous discharge device and said grounding prong element.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA209,975A CA1037554A (en) | 1974-09-23 | 1974-09-23 | Line surge protecting device for telephone lines |
| CA289,837A CA1050101A (en) | 1974-09-23 | 1977-10-31 | Line surge protection device for telephone lines |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA209,975A CA1037554A (en) | 1974-09-23 | 1974-09-23 | Line surge protecting device for telephone lines |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1037554A true CA1037554A (en) | 1978-08-29 |
Family
ID=4101214
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA209,975A Expired CA1037554A (en) | 1974-09-23 | 1974-09-23 | Line surge protecting device for telephone lines |
| CA289,837A Expired CA1050101A (en) | 1974-09-23 | 1977-10-31 | Line surge protection device for telephone lines |
Family Applications After (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA289,837A Expired CA1050101A (en) | 1974-09-23 | 1977-10-31 | Line surge protection device for telephone lines |
Country Status (1)
| Country | Link |
|---|---|
| CA (2) | CA1037554A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1979000660A1 (en) * | 1978-02-24 | 1979-09-06 | G Coren | Clip-on protector |
-
1974
- 1974-09-23 CA CA209,975A patent/CA1037554A/en not_active Expired
-
1977
- 1977-10-31 CA CA289,837A patent/CA1050101A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1979000660A1 (en) * | 1978-02-24 | 1979-09-06 | G Coren | Clip-on protector |
Also Published As
| Publication number | Publication date |
|---|---|
| CA1050101A (en) | 1979-03-06 |
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