SAFETY DEVICE FOR A LIGHT FITTING

The present invention relates to a safety device for a light fitting, which fitting is intended to support at least one essentially rod-shaped lamp, each end of which has at least one contact member, the lamp furthermore having one or more light-emitting members, which are electrically connected between the contact members in the respective ends, one end of the lamp being intended to be connected to a first contact socket and the other end thereof being intended to be connected to a second contact socket in the light fitting, and the first contact socket being connected with a first, and the second contact socket being connected with a second contact line for the supply of current to the lamp.

Prior Art A device intended to be used as a replacement for a previously present fluorescent tube in a fluorescent-tube fitting is known by WO, A1 , 2007/091972. The replacement device consists of a light-emitting diode unit comprising an electrical drive unit, which, on one hand, is connected to a phase conductor, and on the other hand is connected to a zero conductor via a line comprising at least one light-emitting diode but preferably two or more light-emitting diodes connected in series. Light-emitting diodes of the kind in question have considerably lower energy consumption than the corresponding fluorescent tubes.

In a certain embodiment, the light-emitting diode unit consists of a rod, one end of which is connected to a first contact socket, which is connected with the phase conductor, and the other end of which is connected to a second contact socket, which is connected with the zero conductor. Said light-emitting diode rod replaces a straight fluorescent tube present previously. Upon exchange of a present fluorescent tube for such a light- emitting diode rod, the present glow switch is disconnected, alternatively is removed from the seating thereof.

However, in existing light fittings for fluorescent tubes, different forms of electrical connections can be found. The above-mentioned form of

RECORD COPY-TRANSLATICN (Rule 12.4}

connection is denominated single connection and relates to the connecting up of a single fluorescent tube to a mains supply. Other occurring forms of connection are, e.g., series connection, which relates to a plurality of fluorescent tubes, and LLC connection, in which two connection forms glow switches are used, or rapid-start connection and semi-resonance connection, in which glow switches are lacking. In said connections, also different forms of inductors are included. An additional form of connection is a so-called HF connection (high-frequency connection), in which an HF connector is connected to a phase conductor and a zero conductor belonging to a mains supply or another source of power. The feed output from the HF connector to the fluorescent tube consists in turn of two contact lines, which are connected to each a contact socket or a corresponding member. In operation, said contact lines are alternately alive. In this text, no difference is made if the contact sockets are connected directly or indirectly via inductors or HF connectors to phase conductor and zero conductor, respectively. Hereinafter, all lines that feed current to the contact sockets of the light fitting are denominated "contact lines".

A gas-filled fluorescent tube does not conduct current before a voltage has been applied across the two contact ends thereof. On the contrary, a light-emitting diode rod exhibits a conducting connection between the ends thereof, which may entail that at least one contact member in the free end of the rod could become alive and cause personal injury if the rod would be inserted slantingly into a contact socket in such a way that one end thereof would contact a live contact line and the other end thereof became accessible for touch. Hereinafter, light-emitting diode rods as well as other lighting appliances, which have conducting connections, are denominated "lamps".

Summary of the Invention An object of the invention is to provide a safety device for a light fitting that allows a lamp having a line connection between the two ends thereof, for instance a light-emitting diode rod, to be mounted and dismounted in the fitting without the risk of personal injury. Accordingly, the

invention comprises a safety device for a light fitting, which fitting is intended to support at least one essentially rod-shaped lamp, each end of which has at least one contact member, the lamp furthermore having one or more light- emitting members, which are electrically connected between the contact members in the respective ends, one end of the lamp being intended to be connected to a first contact socket and the other end thereof being intended to be connected to a second contact socket in the light fitting, and the first contact socket being connected with a first, and the second contact socket being connected with a second contact line for the supply of current to the lamp. The lamp comprises at least one power switch, which is brought to close the circuit including the light-emitting members when the two ends of the lamp simultaneously are inserted into the respective contact sockets.

A power switch may be arranged at each end of the lamp. The respective power switch may have one or more switching members, which indicate when the lamp is inserted in the respective contact sockets. Said one or more switching members may consist of one or more pressing members projecting from the lamp, which are displaceable into the lamp and which are arranged to close the circuit including the light-emitting members. The pressing members may be arranged on at least one switching body, which is arranged to be displaced into the lamp when the pressing members are brought into contact with the respective contact socket or sockets. The switching body may support at least one guide pin, which is arranged to run into at least one guiding groove when the two ends of the lamp simultaneously are inserted into the respective contact sockets. The inward motion of the guide pin may be arranged to be stopped by at least one guide head if one of the ends of the lamp is inserted into the respective contact socket before the other.

Preferably, the lamp consists of a light-emitting diode rod. The light-emitting diode rod comprises an electrical drive unit, which, on one hand, is connected to the first contact member, and on the other hand is connected to the second contact member via an electrical line, to which a number of light-emitting members in the form of light-emitting diodes are connected. In this case, the power switch may be integrated with the drive

unit and arranged at one end of the light-emitting diode rod. In an alternative embodiment, a power switch may be arranged at each end of the lamp/light- emitting diode rod and the potential drive unit in the case of the light-emitting diode rod be located separated from said power switches.

List of Figures

Figure 1 shows, in a side view, a light fitting that has been converted in order to support a light-emitting diode rod.

Figure 2 shows, in a partly sectioned perspective view, an end of a light-emitting diode rod having the appurtenant safety device according to the invention.

Description of Embodiments

A single-connected light fitting 1 for fluorescent tubes, which is shown in Figure 1 , and which is intended to be attached, e.g., to an underroof or to a wall, supports a light-emitting diode rod 2 provided with one or more contact members at each end thereof. The light-emitting diode rod 2 is arranged between two contact sockets 1.1 , 1.2 and comprises an electrical drive unit 2.1 , which is connected to a first contact line, in this case a phase conductor from an inductor 3, via the left contact socket 1.1 in Figure 1. The light-emitting diode rod 2 is furthermore connected to a second contact line, in this case a zero conductor, via the right contact socket 1.2. An electrical line, to which a number of light-emitting diodes 2.2 are connected, connects the two ends of the light-emitting diode rod 2 and thereby the contact members present at said ends. The drive unit 2.1 is shown schematically in Figure 2.

A conventional light fitting 1 for fluorescent tubes is normally provided with a glow switch, which is connected to one of two contact members in the form of contact pins at each end of the fluorescent tube, but which, when the fluorescent tube is replaced by a light-emitting diode rod 2, is removed from the light fitting 1. The other two contact pins at each end of the fluorescent tube are intended to be connected to the phase conductor from the inductor 3 and to the zero conductor, respectively. The light-emitting

diode rod 2 according to the example has, as well as the fluorescent tube, two cylindrical contact pins 2.3 arranged at each end with the purpose of allowing mounting of the light-emitting diode rod 2 in a light fitting 1 intended for conventional fluorescent tubes. The contact pins of the light-emitting diode rod 2 allow connection to the phase conductor and to the zero conductor no matter how the light-emitting diode rod 2 is inserted into the contact sockets 1.1 , 1.2.

If the light-emitting diode rod 2 mistakenly would be inserted only into the phase-connected contact socket 1.1 , such as is shown by dashed lines in Figure 1 , would at least one of the contact pins 2.3 in the free end become alive and could cause personal injury. In order to prevent this, the drive unit 2.1 comprises a power switch 4, which has two pressing members 4.1 arranged on each side of the contact pins 2.3. The pressing members 4.1 are supported by a switching body 4.2, which is maximally displaced into the light-emitting diode rod 2 when the ends thereof simultaneously are inserted into the contact sockets 1.1 , 1.2 and close the line that is connected with the light-emitting diodes 2.2. A guide pin 4.3, arranged on each side of the switching body 4.2, runs linearly into a guiding groove 4.4 in the drive unit 2.1. If the light-emitting diode rod 2 would be inserted slantingly into the contact socket 1.1 , as has been mentioned above, the power switch 4 is actuated only by one of the pressing members 4.1 , the guide pins 4.3 being pressed slantingly into the drive unit 2.1 and being stopped by the fact that they contact one of two stop heads 4.5, which are arranged on each side of the guiding groove 4.4 on the respective side of the power switch 4. Thereby, the power switch 4 cannot close the line to the light-emitting diodes 2.2 and accordingly not conduct current to the contact pins 2.3 at the end of the light- emitting diode rod 2 accessible for touch.

In an alternative embodiment, the contact members of the lamp 2 at the respective end of the light-emitting diode rod 2 may consist of a disc- shaped member, which projects equally long from the end of the lamp 2 as the above-mentioned contact pins 2.3, and has a thickness that is equal to the diameter of the contact pins 2.3 as well as has a width that corresponds to the spacing between the outer sides of the contact pins 2.3.

The invention is not limited to the embodiments shown here, but may be varied within the scope of the subsequent claims.