EP1050936A1 - Safety bulb holder - Google Patents

Abstract

Socket (1) has safety electric contact system (2) inserted between contact terminal (120) and central contact (12). This ens there is not tension inside socket, mostly on central contact, when not light bulb is inserted in socket. Placing light bulb in socket automatically creates contact between terminal and central contact. An Independent claim is also included for the lamp using the safety socket.

Description

The present invention relates to a safety socket for a electric bulb with screw base or bayonet.

Many electric shock accidents occur when a electric socket, intended to receive an electric bulb, is not equipped with its bulb, while it is connected to a power line under pressure. Safety regulations stipulating that the voltage is applied to the central contact pad of the socket, an accident may occur when a finger or a pin is inserted into the empty socket tool, like a screwdriver, which comes into contact with the central stud of contact.

In the relatively common case where, following an assembly by a unqualified person with socket or power cable voltage phase is applied to the contact tube of the socket, instead of the stud central, an accident can very easily happen since this contact tip is relatively unprotected from the outside, since normally it is connected to the neutral conductor.

Similarly, an accident by electrocution can occur when a bulb is broken in a socket and only a portion of the electrical circuit of the bulb remains energized and is no longer protected by the glass the bulb. In this case also a contact by a finger or a tool can be dangerous.

There are sockets fitted with a switch, which can be operated by hand, to interrupt the power supply circuit of the central stud contact. Since these switches are generally rotatable, it is impossible for the user to know if the pad supply circuit contact center is interrupted or not. The switch of such a socket is rather intended to turn on or off the bulb rather than to operate as security.

A first object of the invention is to propose a socket for safety for a light bulb fitted with a safety device to prevent accidental contact with the central stud of the socket.

A second object of the invention is to propose that the socket previous security is provided with a security device allowing prevent accidental contact with any conductive part accessible from the socket.

These purposes are achieved by a safety socket such as described in claim 1, particular embodiments or variants being described in the dependent claims.

la figure 1 montre schématiquement une portion en coupe d'une douille munie d'un dispositif de sécurité selon une première forme d'exécution de l'invention à l'état de déconnexion,

la figure 2 montre schématiquement la même portion de douille munie d'une variante du dispositif de sécurité selon la première forme d'exécution, à l'état connecté,

la figure 3 montre schématiquement une portion en coupe d'une douille munie d'un dispositif de sécurité selon une deuxième forme d'exécution,

la figure 4 montre schématiquement une coupe selon la ligne IV-IV de la figure précédente,

la figure 5 montre schématiquement une variante de la deuxième forme d'exécution du dispositif de sécurité à l'état connecté,

la figure 6 montre schématiquement une première version d'un dispositif de verrouillage d'un dispositif de sécurité pour une douille,

la figure 7 montre schématiquement, selon une coupe partielle en élévation, une deuxième version d'un dispositif de verrouillage d'un dispositif de sécurité pour une douille,

la figure 8 est une coupe partielle en plan selon la ligne VIII-VIII de la figure précédente, et

la figure 9 montre schématiquement une douille munie d'un dispositif de sécurité selon une troisième forme d'exécution de l'invention.

Several embodiments and variants of a safety socket according to the invention are described below, this description being to be considered with regard to the appended drawing comprising the figures where:

FIG. 1 schematically shows a sectional section of a socket provided with a safety device according to a first embodiment of the invention in the disconnected state,

FIG. 2 schematically shows the same portion of socket provided with a variant of the safety device according to the first embodiment, in the connected state,

FIG. 3 schematically shows a sectional section of a socket provided with a safety device according to a second embodiment,

FIG. 4 schematically shows a section along line IV-IV of the previous figure,

FIG. 5 schematically shows a variant of the second embodiment of the safety device in the connected state,

FIG. 6 schematically shows a first version of a device for locking a safety device for a socket,

FIG. 7 schematically shows, in a partial section in elevation, a second version of a locking device for a safety device for a socket,

FIG. 8 is a partial plan section along the line VIII-VIII of the preceding figure, and

FIG. 9 schematically shows a socket provided with a safety device according to a third embodiment of the invention.

The sockets and devices mentioned below and shown on the figures are only described and represented very schematically, essentially to make them understand how they work. The details of construction and execution, in particular the electrical connections between the various elements, are not described in all their details being within reach of the skilled person.

Conventionally, the socket 1 of FIG. 1, for screw base bulb, includes a threaded metal tube 10, inserted into an insulating support 11 as well as a central contact pad 12. A first contact terminal 100 connected to tube 10 receives the neutral conductor of the socket power cable (not shown), while a second contact terminal 120 receives the phase conductor for supply the central contact pad 12. Usually, the contact terminal 120 is directly connected to the central contact pad 12.

The safety socket of Figure 1 includes a device for safety contact 2, according to a first embodiment of the invention, inserted between the contact terminal 120 and the central contact pad 12. The safety contact device 2 comprises a pusher 20, made of material insulator, able to slide in a hole 110 arranged radially in the sleeve 1 relative to the longitudinal axis of said sleeve, in the tube threaded 10 and the insulating support portion 11 which is directly attached thereto. A first end 200 of the pusher 20 projects inside the tube threaded 10 while the other end 201 of the same pusher projects in an obviously 111 arranged in a portion of the insulating support 11. The end 201 is provided with a contact pad 202 connected electrically, in the variant considered here, to the central contact pad 12. In the obviously 111, directly in front of the patch 202, there is a second pad 203 electrically connected to the contact terminal 120. Des insulating spring means, shown diagrammatically in 204, ensure a separation of the two contact pads 202 and 203, respectively push the pusher 20 so that its end 200 protrudes inside the tube threaded 10.

By inserting a bulb 3 into the socket 1, as shown see in Figure 2, respectively by screwing the base 30 into the threaded tube 10, the pusher 20 is pushed radially outward into the hole radial 110 by the base 30 pressing said first end 200 of which the shape is adapted to this use. At this time the spring means 204 are compressed and the two contact pads 202 and 203 come into contact, thus closing the electrical circuit. As shown in the variant of Figure 1, the safety device 2 is interposed between the terminal contact 120 of the phase conductor and the central contact pad 12, whereas in the variant of FIG. 2, the safety device 2 is interposed between the contact terminal 100 of the neutral conductor and the tube threaded 10.

Generally, a safety socket 1 will be provided with a safety device 2, arranged as in FIG. 1, between terminal 120 of the phase conductor and the central contact pad 12. In this way, we are sure that, if the phase conductor is properly connected to the terminal 120, no tension can appear inside the socket, in particular on the central stud 12, when no bulb 3 is screwed to the socket. The operation of screwing a bulb 3 into the socket automatically establishes contact between terminal 120 and central stud 12.

If we can only assure that the phase conductor, respectively the live conductor will always be connected to terminal 120, i.e. the phase voltage is likely to appear on the threaded tube 10, the socket security will preferably be provided with a second security device 2, arranged as shown in Figure 2, between terminal 100 and the threaded tube 10.

Thus, when a safety socket is provided with a first safety device 2 arranged between phase terminal 120 and the stud central 12 as well as a second security device 2 disposed between the neutral terminal 100 and the threaded tube 10, said socket is completely galvanically isolated when no bulb is attached.

Other constructive arrangements than those described above can be considered for a safety device 2 according to the first proposed form of execution. For example the spring means 204 can be arranged differently from what is shown in the figure or the same effect of connection and disconnection of two contact pads can be obtained by a rocking lever, one end of which projects into the threaded tube.

Such a safety device, according to the first embodiment described above, can also be adapted for a socket intended for receive a bayonet base bulb. We generally know two types of sockets for bayonet bulbs; a first type, generally used for an AC voltage, in which there is a stud contact center, similar to stud 12 described above, and a smooth contact electrically having the same function as the threaded tube 10 described above, and a second type, generally used for a direct voltage, comprising two contact pads arranged side by side at socket bottom. The operation of the safety device will be similar to what was described above, and that's when the pellet is introduced into the contact tube as the pusher projecting into said contact tip is pushed outward, thereby establishing power the element to which it is connected. In the case of a socket of the first type (central stud and contact tube), we can have, as described for screw sockets, only a cutting safety device the electrical supply of the contact pad or else, in addition to this first safety device, a second device cutting the power to the contact tube. In the case of sockets of the second type (two studs of contact side by side), we will preferably have two safety devices each cutting the electrical supply of a stud, since these sockets do not are generally not polarized and that each wire of the power cable can be connected to any contact terminal.

Figures 3 and 4 show a screw socket 1 provided with a safety device 4 according to a second embodiment. In that case, the central contact pad 12 is directly connected to the terminal 120. The safety device 4 consists of a disc 40 consisting essentially of an insulating material and provided with several extensions radial 41, also insulating, each of said extensions 41 being housed in a recess 112 of the insulating support 11 and / or of the threaded tube 10. A spring means 42 is disposed between the bottom of the socket 1 and the disc 40, acting so as to move disc 40 away from the bottom of the socket, respectively of the central contact pad 12. Shoulders 113 limit the recesses 112 towards the outside of the sleeve, preventing the disc 40 coming out of the socket. The insulating disc 40 includes a patch contact 400, arranged in the center of the disc 40 and passing through the disc along the direction of the longitudinal axis of the sleeve.

It is thus understood that when there is no bulb in the sleeve, the disc 40 is pushed back by the spring 42, being guided by the recesses 112 and abutting against the shoulders 113, so to close the bottom of the socket, either to prevent that when introducing a finger or a tool in the socket, it does not come into contact with the central stud 12 energized. By screwing a bulb into the socket, its base repels the disc 40 towards the bottom of the socket, until the contact pad 400 comes into contact with the central stud 12 and ensures contact between said pad and the base contact of the bulb.

As with the first embodiment described above, this second embodiment also includes a variant, visible on the Figure 5, according to which the socket is completely galvanically isolated.

In this case, the disc 40 comprises, in addition to the pellet of contact 400 crossing the disc as before, a crown of contact 401 on its underside, arranged coaxially with the pad 400 and isolated relative to the latter, while the bottom of the socket comprises, in addition to the central stud 12, connected to the terminal 120, two studs 13 and 14 arranged on either side of the central stud 12, facing portions of the crown 401. The stud 14 is connected to the neutral terminal 100, while the stud 13 is connected to the threaded tube 10.

Thus, when a bulb is inserted into the socket and the disc 40 is brought to the bottom of the socket, phase contact is established between the central stud 120 and the base bottom contact 31 by through the central pad 400, while the neutral contact goes through terminal 100, pad 14, crown 401, pad 13 and the tube threaded 10.

Execution variants are also possible for this second embodiment of the safety device. For example the disc 40 has been shown with four radial extensions 41, but it is obvious that he could understand a different number. Preferably the disc 40 will be provided with at least two radial extensions 41. Similarly, the spring means 42 may be arranged differently from what is shown here. On the other hand, the element described as crown 401 can consist only of a conductive portion on the underside of the disc 40, this conductive portion connecting, when the disc 40 is pushed to the bottom of the socket, the two studs 13 and 14 arranged in any places on the bottom of the socket.

As for the first embodiment of the safety, this second embodiment can be adapted to the sockets bayonet of either of the types described. For the sockets of first type (central stud and contact tube), construction and operation of the safety device are similar to what has been described above. For sockets of the second type (two contact pads side by side), the disc 40 will have two through contact pads, each being able to put one of the pads in contact with the contact of corresponding base of the lamp base.

If a safety socket fitted with a device according to one or the other of the described variants of the second embodiment presented already offers a first level of security by preventing contact accidental with a portion of the socket under tension, a device complementary locking of the disc 40 in a position remote from the stud central 12 may be appropriate so as to avoid that the disc 40 can be moved by pressing it in with a finger or a tool, without a light bulb is introduced into the socket.

A first version of a locking device 5 is shown schematically in plan in Figure 4 and in elevation on the Figure 6. The locking device 5 consists here of a lever 50 mounted on a pivot 51 able to pivot around an axis 511 perpendicular to the axis longitudinal of the sleeve as well as sliding along said axis 511. The lever 50 includes a shoulder 52 comprising an inclined plane 520 and a flat 521 as well as a push button 510 protruding out of the external wall of the socket 1. The device is completed by a first means spring 53, shown here by a leaf spring, suitable for holding the lever 50 in the locked position, i.e. parallel to the longitudinal axis of the socket as well as a second spring means 54 capable of repelling radially the lever 50, respectively the push button 510 towards outside. The lever 50 is able to pivot by a determined angle around axis 511 and slide of a determined value, in a housing 114 fitted for this purpose in the insulating support 11. The radial extension 41 la closer to the locking device 5 comprises a notch 410, turned towards the side of the locking device and slightly wider greater than the thickness of the lever 50.

When a bulb is placed in the socket and it is removed by unscrewing it, the disc 40 accompanies the movement of removal of the bulb base, being pressed by the spring 42 seen in FIG. 3. During this movement, the radial extension 41 meets the inclined plane 520 and rotates the lever 50 in the direction indicated by the arrows in FIG. 6. When the radial extensions 41 of the disc 40 come into abutment against the shoulders 113, the lever 50 returns to the rest position under the action of the leaf spring 53, the flat 521 then preventing a new displacement from disc 40 towards the bottom of the socket, retaining the extreme portion of the radial extension 41, as seen in plan on the lower portion of Figure 4. The disc 40 is thus locked in position such that a contact with the central stud is impossible. In order to allow the installation of a new bulb in the socket, it is necessary to unlock the disc 40. For this, it is enough to press the push button 510, which pushes the lever 50 towards the notch 410, as seen on the portion upper of Figure 4. Thus the disc 40 is unlocked and can lower towards the bottom of the socket during the insertion of the bulb in order to to allow the central pad 12 to come into contact with the bottom contact bulb base, studs 13 and 14 respectively with the crown 401. Preferably there will be two locking devices 5, each acting on an opposite radial extension relative to the axis longitudinal of the socket. In this way, the disc 40 is held by two opposite extensions, avoiding skewing and unlocking requires to act in opposition at two opposite points of the socket.

According to another version of a locking device visible on Figures 7 and 8, the locking device 6 operates fairly similar to the one just described above, the difference being that unlocking takes place automatically when a bulb in the socket. For this, the device 6 is provided with a pusher 60, similar to the pusher 20 described above with reference to FIG. 1, the end of the pusher 60 disposed in the recess 111 carrying a lever 61 provided like the lever 50 seen above with a stop flat. In this case, the movement of the lever 61 to unlock the disc 40 is done radially outward.

By inserting a bulb into the socket, the base comes push the pusher 60 outwards, in opposition to the spring 62, as described above with reference to FIGS. 1 and 2. The lever 61 is thus displaced so as to release the extension 41 retained by the flat, respectively allow the disc 40 to move towards the bottom of the sleeve. When we removes the bulb, the disc 40 is pushed by the spring 42 until the extensions 41 come into abutment against shoulders 113, removal complete with the bulb releasing the pusher 60, which under the effect of the means to spring 62 blocks the extension 41 under the flat portion of the lever 61. According to this latest version, the locking means 6 are actuated automatically when a bulb is inserted or removed and does not therefore require no manipulation for their actuation.

It is obvious that the edges of the elements of the device for operational contact locking, e.g. extension edge radial 41 in contact with the lever 50 or 61 according to one or the other of the described versions, are formed, for example bevelled or rounded, of so as to facilitate the sliding of these elements between them.

Other versions or variants of the locking device can be considered. For example, the upper portions of guide recesses 112 may each include an obviously additional, disposed on a portion of the periphery of the sleeve, perpendicular to the corresponding guide recess, the disc 40 further comprising a control lever, for example a radial extension of an extension 41, accessible from outside the socket, said lever allowing, when the disc is in the stop position in the upper portion of the guide recesses, to rotate it a portion of a tower so as to engage the extensions in the additional recesses, so as to lock the disc, a pivoting in the opposite direction to unlock it. Said lever can be operated manually or using a tool. Similarly in variant of pusher 60 of FIGS. 7 and 8, one could have a lever pivoting, controlling the lever 61, and one end of which would protrude into the threaded conductive tube 10.

It is evident that the versions described above of the means of disc lock 40 can also be adapted to a disc 40 arranged in a bayonet socket in either of the types mentioned upper.

FIG. 9 shows another safety device 7 intended for detect the presence or absence of a bulb 3 in the socket. In this case, instead of detecting the presence or absence of the base 30 in the tube threaded 10 as described so far, the device 7 detects the presence or the absence of the glass 32 of the bulb 3. This safety device is particularly useful in order to prevent a portion of the bulb 3 from remaining under tension when the glass 32 is broken, in particular by vandalism.

The safety device 7 here consists of at least one lever or pusher 70, suitable under the effect of a spring means 71 to detect the presence or absence of glass 32. In the embodiment shown in the figure, the pusher 70 is housed in a recess 115 of the support insulator 11 and is able to slide parallel to the longitudinal axis of the socket. A spring 71 pushes the pusher 70 outwards, respectively towards the glass 32 so that a first end 72 of the pusher can come into contact with the glass 32. The other end of the pusher 70 is provided with a contact means 73 capable of establishing a connection electric with a second contact means 74.

We see in the figure that the end 72 of the pusher 70 drawn on the left side does not detect the presence of a glass 32, causing the pusher is pushed completely outward under the effect of the spring 71 interrupting the electrical connection between the contact means 73 and 74, while the end 72 of the pusher drawn on the right-hand part detects the presence of a glass 32, causing the pusher to be pushed towards the interior establishing the electrical connection between the contact means 73 and 74.

Since when a glass 32 is broken, fragments of glass are likely to remain attached to the base 30, it may be advantageous to have several security devices 7 capable of detecting the presence of the glass 32 on the periphery of the socket, so that in the case of glass broken, at least one push-button 70 is actuated to cut the circuit power supply. In this case, it is advantageous that the means of contact 73 and 74 of each of the pushers 70 are mounted in series, as shown in the figure.

As before, variant embodiments can be envisaged, in particular the replacement of pushers 70 with levers tilting.

FIG. 9 shows yet another safety device 8, independent of the previous one, consisting of a micro fuse 80 mounted on the circuit connecting the phase terminal 120 and the central contact pad 12. The micro fuse 80 can be changed from outside the socket.

The safety device 7 for detecting the glass 32 can be used alone or in combination with any of the security described above. Safety device 8 by micro fuse 80 is generally used in combination with either safety devices described above.

A safety socket in either form of execution or variants described finds numerous applications. Through example it can be used as a socket mounted on a luminaire intended for a children's room. Several safety sockets can also be mounted in parallel so as to form a garland luminous, for decoration or for the protection of a site by example. In this case, these garlands are quite often subjected to vandalism, theft or broken bulbs, subsequent electrocution may be avoided.

The safety sockets described here are particularly applicable well to installations operating at usual voltage, for example at 220V, but they could also be used for functioning installations at higher or lower voltage, as well as at all frequencies usual.

Claims (19)

1. Socket (1) for an electric bulb comprising at least one contact pad (12) disposed at the bottom of the socket and a first contact terminal (120) for a first conductor, in particular a phase conductor, as well as a second contact terminal (100) for a second conductor, in particular a neutral conductor,
characterized in that it further comprises
at least one safety device (2; 4; 7) capable of detecting the presence or absence of an electric bulb (3) in said socket and of interrupting at least the electric circuit connecting the first contact terminal (120) and the contact pad (12) when it has detected the absence of a light bulb. 2. Socket according to claim 1, comprising a conductive tube (10) inserted in an insulating support (11), characterized in that it further comprises a second safety device (2; 4) capable of interrupting the electrical circuit connecting the second contact terminal (100) and the conductive tube (10) when it has detected the absence of a light bulb. 3. Socket according to claim 1, comprising a second contact pad disposed next to the first contact pad (12), characterized in that it further comprises a second safety device (2; 4) capable of interrupting the circuit electric connecting the second contact terminal (100) and said second contact pad when it has detected the absence of an electric bulb. 4. Socket according to one of the preceding claims, characterized in that said safety device (2) comprises a pusher or a lever made of insulating material (20) having a first end (200) projecting inside the socket and a second end (201) disposed in a recess (111) of the insulating support and provided with a first contact pad (202), a second contact pad (203) being disposed in said recess (111) opposite said first contact pad (202), spring means (204) being provided to separate said contact pads from each other, the introduction of a base (30) of an electric bulb (3) into said socket actuating said pusher or said lever and bringing the two said contact pads (202,203) into contact. 5. Socket according to claim 4, characterized in that one of said pads (202) is electrically connected to said contact pad (12) while the other of said pads (203) is electrically connected to said first contact terminal ( 120). 6. Socket according to claim 4, characterized in that one of said pads (202) is electrically connected to said conductive tube (10) while the other of said pads (203) is electrically connected to said second contact terminal (100 ). 7. Socket according to one of claims 1 to 3, characterized in that said safety device (4) comprises a disc (40) made of insulating material provided with a plurality of radial extensions (41), said disc being disposed in said bushing so that the plane of said disc is essentially perpendicular to the longitudinal axis of the bushing (1), said disc being able to slide in the direction of said longitudinal axis of the bushing, being pressed by spring means (42) to move away from the bottom of the sleeve, said radial extensions (41) being able to slide in recesses (112) arranged in the sleeve so as to guide said disc, a stop (113) being provided in at least a recess (112) so as to limit the sliding of the disc (40) towards the outside of the sleeve, said disc further comprising at least one conductive pad (400) passing through said disc capable of establishing electrical contact between a contact pad (12) and a contact (31) at the bottom of the base of the electric bulb when the disc (40) is pressed against the bottom of the socket by said bulb introduced into the socket. 8. Socket according to claim 7, characterized in that said disc (40) further comprises a conductive track (401), isolated from the conductive pad (400) and disposed on the face of said disc facing the bottom of the socket, said socket bottom further comprising two contact pads (13,14) each arranged opposite a portion of said conductive track, one of said contact pads (14) being electrically connected to the neutral conductor terminal ( 100), the other of said contact pads (13) being connected to said conductive tube (10). 9. Socket according to one of claims 7 or 8, characterized in that it further comprises at least one locking device (5; 6) capable of locking said disc (40) in a position remote from the bottom of the socket. 10. Socket according to claim 9, characterized in that the unlocking of the locking device (5) is controlled manually. 11. Socket according to claim 9, characterized in that the unlocking of the locking device (6) is automatically controlled during the introduction of a bulb into the socket. 12. Sleeve according to one of claims 9 to 11, characterized in that said locking device comprises a lever (50,61) pivotally mounted on a pivot (51) essentially perpendicular to the longitudinal axis of the sleeve, said lever comprising inclined plane (520) cooperating with an edge of a portion of the radial extension (41) associated with said locking device to pivot said lever during movement of the disc (40) under the action of the spring means ( 42) as well as a flat (521) acting as a stop against a portion of said radial extension (41) in order to lock the disc in a position remote from the bottom of the sleeve. 13. Socket according to one of claims 9 to 10 or 12, characterized in that the lever (50) of said locking device is axially movable under the action of an actuating means (510) disposed outside of the sleeve, capable of sliding said lever along the radial extension until it arrives opposite a notch (410) of said radial extension, thereby unlocking the disc. 13. Socket according to one of claims 9 or 11 to 12, characterized in that the lever (61) of said locking device is axially movable under the action of an actuating means (60) disposed inside of the sleeve, capable of sliding said lever along the radial extension until it arrives opposite a notch (410) of said radial extension, thereby unlocking the disc. 14. Socket according to one of the preceding claims, characterized in that it further comprises a safety device (7) capable of detecting the presence or absence of the glass (32) of an electric bulb (3) on said socket and to interrupt at least the electrical circuit connecting the first contact terminal (120) and the central contact pad (12) when it has detected the absence of said glass from an electric bulb. 15. Socket according to claim 14, characterized in that said safety device comprises at least one pusher (70) capable of sliding parallel to the longitudinal axis of the socket in a recess (115) of the insulating support (11), a spring means (71) being able to push a first end (72) of said pusher out of said socket, so as to detect the presence or absence of said glass (32), the other end of said pusher being provided with a first contact means (73) cooperating with a second fixed contact means (74), said contact means closing the supply circuit of the central contact pad (12) from said first contact terminal (120) when said first end (72) pusher (70) has detected the presence of a glass (32) on the sleeve and opening said supply circuit when said first end (72) of pusher (70) has detected the absence of a glass (32) on the socket. 16. Socket according to claim 15, characterized in that it comprises a plurality of said pushers (70) distributed regularly over the end periphery of the socket, said contact means (73,74) of each of said pushers being mounted in series between said first contact terminal (120) and said central contact pad (12). 17. Socket according to one of the preceding claims, characterized in that it further comprises a housing for a micro fuse (80) disposed in the supply circuit of the central contact pad (12). 18. Luminous device provided with at least one safety socket according to one of the preceding claims.

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