GB2319901A

GB2319901A - Auto switched lampholder

Info

Publication number: GB2319901A
Application number: GB9624387A
Authority: GB
Inventors: John Lilley
Original assignee: Lilley & Son Ltd S
Current assignee: Lilley & Son Ltd S
Priority date: 1996-11-23
Filing date: 1996-11-23
Publication date: 1998-06-03
Also published as: GB9624387D0

Abstract

A lampholder comprising a socket 19 to receive a cap part 20 of an electric lamp 21 a retaining means 23 engage a portion 22 of the cap part to retain the cap part in the socket, electrical contact means 33 adapted to engage contacts located on the cap part, terminal means 37 adapted to be connected to an electric supply and electrically conductive means 33 to connect the electrical contact means to the terminal means, sensing means 50, 58 to sense whether or not the cap part of the lamp is retained by the retaining means, and switch means 38, 40 responsive to the sensor means 50, 58 to make or break electrical contact between the contact means and the terminal means. Sensor means 50, 58 cam an insert containing the switch terminals 40. Terminals 40 are joining to respective contacts 33 by springs 36, spring 53 returns sensor 50 which cams the insert to a switched off position when the lamp is uncoupled.

Description

Title: Auto Switched Lampholder Description of Invention This invention relates to a lampholder hereinafter referred to as of the kind specified, comprising a socket to receive a cap part of an electric lamp, a retaining means to engage a portion of the cap part to retain the cap part in the socket, electrical contact means adapted to engage contacts located on the cap part, terminal means adapted to be connected to an electric supply and electrically conductive means to connect the electrical contact means to the terminal means.

Hitherto when the lamp is removed from such a lampholder, the electrical contact means are exposed which can present a risk of electrocution.

An object of the invention is to provide a new or improved lampholder whereby this problem is reduced or overcome.

According to one aspect of the invention, we provide a lampholder of the kind specified having sensing means to sense whether or not the cap part of the lamp is retained by the retaining means, and switch means responsive to the sensor means to make or break electrical contact between the contact means and the terminal means.

Said sensor means may comprise a pair of sensor members, each biased to a first position when no lamp is present in the retaining means, and moveable to a second position when a lamp is introduced into said retaining means.

Said switch means may comprise a moveable switch member.

Said switch member may be moveable between a first position hereafter referred to as a break state in which no electrical connection is made between the contact means and the terminal means, and a second position hereafter referred to as a make state in which an electrical connection is made between said contact means and said terminal means.

Means responsive to the first of said sensor members may be provided which act on said switch member to move said switch member from its make position to its break position when said sensing member is moved from its second position to its first position.

Said first sensor member may in its first position hinder the passage of the switch means from its break position to its make position, and in its second position permit said switch means to move from its break position to its make position.

Means responsive to said second sensor member may be provided which act on said switch member to move the switch member from its break position to its make position when the second sensor means moves from its first position to its second position.

The switch member may be provided with an opening through which the first sensor member extends.

Said means responsive to said first sensor member may comprise a first cam means engage able with a first cam follower to move the switch means from its make position to its break position.

Said means responsive to said second sensor member may comprise a second cam means to engageable with a second cam follower to move the switch means from its break position to its make position.

The first and second cam means may be provided on said first and second sensor members respectively, and may be disposed at or towards their lower ends.

The first and second cam followers may each comprise a portion of the switch member which is engageable by the first cam and second cam respectively.

The first cam follower may comprise an end wall of said opening in the switch member.

The first cam means first may be provided with a first portion which prevents movement of the switch means from its break to make position when the first sensor member is in its first position, and a second portion to engage the first cam follower to move the switch means from its make position to its break position.

Alternatively the first cam means may have a profile such that the resistance presented by the first cam means to the movement of the switch from its break to its make position decreases as the first sensor member moves from its first to its second position. Such a profile may for example comprise straight cam surfaces of different inclination and/or a curved cam surface.

Said electrically conductive means may comprise a flexible portion attached at one end to the switch member, the other end being electrically connected with said contact means Bias means may be provided to resist movement of the switch member from its make and/or break positions.

The invention will now be described by way of example only with reference to the accompanying drawings wherein FIGURE 1 is an exploded perspective view of part of a lamp holder embodying the invention.

FIGURE 2 is a cross section through a complete lamp holder embodying the invention, showing the lampholder with a light bulb retained in engagement therewith, and FIGURE 3 is a cross section similar to that of Figure 2 but showing the lampholder without a lightbulb retained in engagement therewith; FIGURES 4-6 are views of a lampholder similar to those in Figures 1-3 respectively but with the cam on the second sensor member having a different profile.

Referring to the drawings, a lampholder comprises a lower housing part 10 and an upper housing part 11 which is releasably secured to the lower housing part 10 by a flanged sleeve 12 having an internal thread 13 in engagement with an external thread 14 of the lower housing part 10, the sleeve 12 and upper housing part 11 having co-operating shoulders as indicated at 15. The housing parts and sleeve 12 are made as brass pressings but may be made of other material such as plastics moulding.

The lower housing part 10 has a boss 16 through which an electrical supply lead, not shown, may extend and having a threaded portion 17 with which a nut 18 is engaged, whereby the lampholder may be mounted in an aperture in a support member, not shown.

The upper housing part 11 is of generally cylindrical configuration to provide a socket 19 in which a cap part 20 of a conventional bayonet cap-type electric lamp 21 is received and retained by engagement of diametrically opposed pins 22 of the cap 20 being received in conventionally generally Lshaped slots 23.

Mounted within the housing parts 10, 11 are upper and lower body parts 30, 31 respectively. The upper body part 30 is provided with contact means 32 comprising a pair of pins 33 which are slidably mounted in apertures 34 provided in a guide part 35 moulded integrally with the member of the upper body part and depending downwardly from an upper wall 35a thereof. The pins 33 are normally biased upwardly in the axial direction of the socket by coil helical springs 36. Each pin 33 is connected by an electrical conducting means to a respective terminal 37 to which an electrical supply wire can be connected in conventional manner. Each terminal means 37 is connected to a fixed contact 38 of a switch means 39 which can occupy a make or a break state to provide electrical connection, via movable contacts 40 and the helical spring 36, with the pins 33. The lower ends of the spring 36 are received in pockets 41 of the movable contacts 40 which are made of generally channel shape brass strips mounted in an arm 42 which is moulded integrally with an operating member 43 of an actuating means of the switch 39.

The operating member 43 is mounted for sliding movement transversely to the axial direction of the lampholder. The operating member 43 has downwardly projecting parts 46 adapted to co-operate with raised detent parts 47 of the lower part 31 so that the operating member 43 can be releasably retained in a make condition, shown in Figure 2, in which the movable contacts 40 are in engagement with the fixed contacts 38 provided on the lower mounting part 31 and a break condition, shown in Figure 3, in which the movable contacts 40 are displaced laterally out of engagement with fixed contacts 38. The helical springs 36 flex as shown in chain dotted line in Figures 2 and 3 to permit of such movement of the movable contacts 40 whilst providing an electrical conducting path between the movable contacts 40 and the contact means provided by the pins 33.

The lampholder is provided with a first sensor member 50 slidable in the axial direction of the socket 19 in a guide passage 52 and being resiliently biased in the direction outwardly of the socket 19 by a helical spring 53 received in a recess 54 in the lower body part 31 within which a peg part 55 of the sensor member is engaged. The first sensor member 50 is provided with a first cam 56 disposed at or lower at its lower end. The sensor member 50 is received in a slot 57 provided in the switch member 43. The surface of the slot abutting the cam 56 provides a corresponding first cam follower 57a.

A second sensor member 58 is provided being slidable in the axial direction of the socket 19 in a guide passage 59 and being biased in a direction outwardly of the socket 19 by an extended helical spring 60. A flange 61 is provided on the sensor member 58 such that the helical spring 60 is disposed concentrically with the sensor member 58 and abuts the flange 61 and a surface 62 of the body parts 30. A second cam 63 is provided at the lower end of the sensor member 58 having an inclined surface 64 which engages with a second cam follower provided by a surface 65 of the operating member 43.

In use, when a lamp 21 is engaged with the socket 19 and a cap 20 thereof retained therein, contact portions of the cam press the pins 33 against the bias of the springs 36 and sensor members 50 and 58 against the resistance of the springs 55 and 60 respectively. The inclined surface 64 of the second cam 63 engages the second cam follower 65 of the switch member, causing the switch member 43 to move in a lateral direction from the break position to the make position. The first sensor member is depressed such that the first cam 56 does not project into the opening 57 in the switch member 43 and so does not hinder its movement. The helical spring 36 is moved into electrical contact with the contact means.

When the lamp 21 is removed from the socket as shown in Figure 3 the pins 33 are biased outwardly by the helical springs 36 and similarly the sensor members 50, 58 move outwardly to their first positions. The first surface portion 56a of the cam 56 attached the cam follower 57 and causes the switch member 43 to move from its make position to its break position. The second sensor member 58 returns to its first position and so does not hinder the movement of the switch member. Consequently, when no lamp is present in the socket, the pins are isolated.

Once the switch member 43 is in its break position, the second surface portion 56b of the first cam 56 is disposed within the slot 57 of the switch member 43. If only the second sensor member 58 is depressed the switch member 43 is brought into abutment with the second surface portion 56h of the first cam 56 and hence, the first cam 56 hinders movement of the switch member from its break position to its make position. Consequently, the pins cannot be connected to the electricity supply purely by pressing either of the sensor members alone.

The surface 56c of the first cam 56 may be of other profile such as curved in profile as shown in Figures 4 to 6. In this case the first cam 56 hinders the switch member 43 moving from the break to make position but connection can be made if sufficient force is applied to the second sensor member 58. If desired the cam may comprise straight cam surfaces of differing slope.

Although as described in the above example, and as preferred, a bayonet type fitting is provided, the invention may be applied to a lamp holder for a screw in lamp. The invention may also be applied to lamp holders for other kinds of lamp such as a fluorescent lamp having a similar single cap for being received and retained in a lamp holder. In addition the invention may be applied to lamp of the kind having two caps at opposite ends such as an incondecent or fluorescent tube where the lamp holder is provided with two sockets, one for each cap. In such a case one or each socket may be provided with sensing means to sense the presence or absence of a cap being retained in the socket.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

1. A lampholder comprising a socket to receive a cap part of an electric lamp, a retaining means to engage a portion of the cap part to retain the cap part in the socket, electrical contact means adapted to engage contacts located on the cap part, terminal means adapted to be connected to an electric supply and electrically conductive means to connect the electrical contact means to the terminal means, sensing means to sense whether or not the cap part of the lamp is retained by the retaining means, and switch means responsive to the sensor means to make or break electrical contact between the contact means and the terminal means.

2. A lampholder according to claim 1 wherein said sensor means comprises a first sensor member and a second sensor member, each biased to a first position when no lamp is present in the retaining means, and moveable to a second position when a lamp is introduced into said retaining means.

3. A lampholder according to claim 2 wherein said switch means comprises a moveable switch member.

4. A lampholder according to claim 3 wherein said switch member is moveable between a first position hereafter referred to as a break state in which no electrical connection is made between the contact means and the terminal means, and a second position hereafter referred to as a make state in which an electrical connection is made between said contact means and said terminal means.

5. A lampholder according to claim 4 wherein means responsive to the said first sensor member may be provided which act on said switch member to move said switch member from its make position to its break position when said sensing member is moved from its second position to its first position.

6. A lampholder according to claim 5 wherein said first sensor member in its first position hinders the passage of the switch member from its break position to its make position, and in its second position permits said switch member to move from its break position to its make position.

7. A lampholder according to claim 5 or claim 6 wherein said means responsive to said first sensor member comprises a first cam means engageable with a first cam follower to move the switch means from its make position to its break position.

8. A lampholder according to claim 7 wherein the first cam means is provided on said first sensor member and is disposed at or towards its lower end

9. A lampholder according to claim 7 or claim 8 wherein the first cam follower comprises a portion of the switch member which is engageable by the first cam means.

10. A lampholder according to any one of claims 5 to 9 wherein the switch member is provided with an opening through which the first sensor member extends.

11. A lampholder according to claim 10 where dependent on claim 9 wherein the first cam follower comprises an end wall of said opening in the switch member.

12. A lampholder according to any one of claims 7 to 11 wherein the first cam means is provided with a first portion which prevents movement of the switch means from its break to make position when the first sensor member is in its first position, and a second portion to engage the first cam follower to move the switch means from its make position to its break position.

13. A lampholder according to any of claims 7 to 11 wherein the first cam means has a profile such that the resistance presented by the first cam means to the movement of the switch from its break to its make position decreases as the first sensor member moves from its first to its second position.

14. A lampholder according to claim 15 wherein the profile comprises straight cam surfaces of different inclination and/or a curved cam surface.

15. A lampholder according to any of claims 4 to 14 wherein means responsive to said second sensor member is provided which acts on said switch member to move the switch member from its break position to its make position when the second sensor member moves from its first position to its second position.

16. A lampholder according to claim 15 wherein said means responsive to said second sensor member comprises a second cam means engageable with a second cam follower to move the switch means from its break position to its make position.

17. A lampholder according to claim 16 wherein the second cam means is provided on said second sensor member and is disposed at or towards its lower end.

18. A lampholder according to claim 16 or claim 17 wherein the second cam follower comprises a portion of the switch member which is engageable by the second cam means.

19. A lampholder according to any one of the proceeding claims wherein said electrically conductive means comprises a flexible portion attached at one end to the switch member, the other end being electrically connected with said contact means

20. A lampholder according to any one of the proceeding claims wherein bias means is provided to resist movement of the switch member from its make and/or break positions.

21. A lampholder substantially as described herein with the accompanying drawings.

22. Any novel feature or novel combination of features described herein and/or in the accompanying drawings.