GB1572234A

GB1572234A - Mining lamp

Info

Publication number: GB1572234A
Application number: GB2026878A
Authority: GB
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 1977-06-22
Filing date: 1978-05-17
Publication date: 1980-07-30
Also published as: DE2728145A1; FR2395459A1; BE868351A

Description

(54) MINING LAMP (71) We, SIEMENS AEETIBNGESBLL SCHAFT, a German company of Berlin and Munich, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particulally described in and by the following statement: This invention relates to a mining lamp, that is to a lamp for use in underground mining.

According to one aspect of the present invention, there is provided a mining lamp comprising: a) a light-permeable protection tube closed at both ends with sealing compound and adapted to contain a fluorescent tube; b) a lead for supplying the fluorescent tube with current provided with means for connecting the lamp to an intrinsically safe direct current source, at least part of the lead being embedded in the sealing compound at one end of the protection tube; and c) a chopper for interrupting the current supplied to the fluorescent tube, the chopper also being embedded in the sealing compound at said one end of the protection tube.

According to another aspect of the present invention, there is provided the combination of a lamp according to said one aspect and a battery serving as an intrinsically safe direct current source.

In the field of underground mining, lamps are used which consist essentially of a light source, such as an incandescent or glow lamp, and an adjustable parabolic reflector. Such a lamp may be fixed to a safety helmet or may be used as a manually portable lamp. However, the light yield of an incandescent or glow lamp with the power available is small and the resultant illumination of the work site is weak due to the narrow light cone emitted by the lamp despite the adjustability of the reflector.

In order that the present invention may be more fully understood, an embodiment of a lamp according to the present invention will now be described, by way of example, with reference to the accompanying drawing, in which: Figure 1 shows a diagrammatic longitudinal section of parts of the lamp; and Figure 2 is a diagrammatic representation of a battery for the lamp.

Referring to Figure 1, a fluorescent tube 1 is inserted into a protection tube 2 made of light-permeable material and is centred by means of discs 3. One end of the protection tube is closed by a sealing compound shaped into an end cap 4. Disposed centrally, for instance, in the end cap 4, and embedded therein, is a screw socket 5 into which a suspension eye or magnet can be screwed for mounting of the lamp at the work site. Fixed to the end cap 4 are connecting pins 6 for connection with the fluorescent tube. The conductors required to operate the fluorescent tube and leading to the connecting pins 6 are disposed inside the protection tube 2, expediently in the vicinity of an arcuate reflector, e.g. a reflector internally coated with reflective material, extending over the length of the protection tube and, for instance, around about a third of and not more than half of the periphery of the protection tube The other end of the protection tube 2 is similarly closed by a member 7 made of a sealing compound in which are embedded a chopper 8 for interrupting the current supplied to the fluorescent tube and, if necessary, current limiting means 9 and the end of a connecting lead 10. The cross-section of the member 7 is circular for instance, and tapers towards the connection side in the shape of a frustum of a cone. Expediently, a screw socket 5' is disposed in the member 7 and is preferably embedded therein. The member 7 is advantageously formed in the shape of a handle. The connecting lead 10 is connected to connecting means in the form of a standard plug 11 which can be introduced into the plug socket (not shown) of an intrinsically safe current source having a voltage of 12V at 1A, the plug and/ or plug socket being provided with means to prevent the poles of the plug being connected to the wrong poles of the socket.

So that the lamp can also be used independently of an intrinsically safe mains power supply system, an intrinsically safe power supply unit, for example a battery, built into a housing and consisting of rechargeable cells, may be used as the intrinsically safe direct current source, of which the connections are connected via a current and voltage limiting electronic circuit to a plug socket disposed in the housing.

Figure 2 shows diagrammatically a battery 12 provided to supply the intrinsically safe lamp, the battery being composed of rechargeable cells. The number and circuit arrangement of the cells is such that the battery yields a voltage of 12 V and a current of 1 A. Disposed in the housing 13 of the battery, apart from the rechargeable cells, is a voltage and current limiting circuit 14 and a plug socket 15. The circuit 14 is actuated, for instance, by introducing the plug 11 of the lamp into the plug socket 15 or by a push button switch 16 which is operated from outside the housing. If the cells, the circuit 16, the plug socket 15 and the switch 16 are embedded in a sealing compound, the housing 13 may be omitted.

In conjunction with the battery acting as the intrinsically safe current source, the lamp can be used at any site underground independently of a mains power supply system.

Mounting the fluorescent tube within a protection tube whose ends are closed by sealing compound and embedding the chopper and the supply line in the sealing compound at one end ensures that the lamp is intrinsically safe. The fluorescent tube operates with uniform light distribution and with high light yield.

Such a lamp is particularly portable and is advantageous for use in assembly operations in underground mining.

The screw socket may be replaced by some other form of connection such as a bayonet fitting.

WHAT WE CLAIM IS: 1. A mining lamp comprising a) a light-permeable protection tube closed at both ends with sealing compound and adapted to contain a fluorescent tube; b) a lead for supplying the fluorescent tube with current provided with means for connecting the lamp to an intrinsically safe direct current source, at least part of the lead being embedded in the sealing compound at one end of the protection tube; and c) a chopper for interrupting the current supplied to the fluorescent tube, the chopper also being embedded in the sealing compound at said one end of the protection tube.

2. A lamp according to claim 1, further comprising a fluorescent tube disposed within the protection tube.

3. A lamp according to claim 1 or 2, wherein the sealing compound at said one end of the protection tube is in the shape of a handle.

4. A lamp according to claim 1, 2 or 3, wherein the sealing compound at the other end of the protection tube is in the shape of an end cap.

5. A lamp according to any preceding claim, wherein current limiting means are also embedded in the sealing compound at the said one end of the protection tube.

6. A lamp according to any preceding claim, wheerin the protection tube is provided with an arcuate reflector extending around not more than half the periphery of the protection tube.

7. A lamp according to claim 6, wherein connecting pins for connection with the fluorescent tube are fixed to the sealing compound at the other end of the protection tube and conductors connected to the pins extend within the protection tube in the vicinity of the reflector.

8. A lamp according to any preceding claim, wherein a screw socket is fixed to the sealing compound at the other end of the protection tube for mounting the lamp.

9. A lamp according to claim 8, wherein the screw socket is embedded in the sealing compound at the other end of the protection tube.

10. A lamp according to claim 8 or 9, wherein a further screw socket is embedded in the sealing compound at said one end of the protection tube for mounting the lamp.

11. A lamp substantially as hereinbefore described with reference to, and/or as illustrated in, Figure 1 of the accompanying drawing.

12. The combination of a lamp according to any preceding claim and a battery serving as an intrinsically safe direct current source.

13. A combination according to claim 12, wherein the battery comprises, within a housing, rechargeable cells, a current and voltage limiting circuit and a plug socket.

14. A combination according to claim 13, wherein the current and voltage limit

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. a frustum of a cone. Expediently, a screw socket 5' is disposed in the member 7 and is preferably embedded therein. The member 7 is advantageously formed in the shape of a handle. The connecting lead 10 is connected to connecting means in the form of a standard plug 11 which can be introduced into the plug socket (not shown) of an intrinsically safe current source having a voltage of 12V at 1A, the plug and/ or plug socket being provided with means to prevent the poles of the plug being connected to the wrong poles of the socket. So that the lamp can also be used independently of an intrinsically safe mains power supply system, an intrinsically safe power supply unit, for example a battery, built into a housing and consisting of rechargeable cells, may be used as the intrinsically safe direct current source, of which the connections are connected via a current and voltage limiting electronic circuit to a plug socket disposed in the housing. Figure 2 shows diagrammatically a battery 12 provided to supply the intrinsically safe lamp, the battery being composed of rechargeable cells. The number and circuit arrangement of the cells is such that the battery yields a voltage of 12 V and a current of 1 A. Disposed in the housing 13 of the battery, apart from the rechargeable cells, is a voltage and current limiting circuit 14 and a plug socket 15. The circuit 14 is actuated, for instance, by introducing the plug 11 of the lamp into the plug socket 15 or by a push button switch 16 which is operated from outside the housing. If the cells, the circuit 16, the plug socket 15 and the switch 16 are embedded in a sealing compound, the housing 13 may be omitted. In conjunction with the battery acting as the intrinsically safe current source, the lamp can be used at any site underground independently of a mains power supply system. Mounting the fluorescent tube within a protection tube whose ends are closed by sealing compound and embedding the chopper and the supply line in the sealing compound at one end ensures that the lamp is intrinsically safe. The fluorescent tube operates with uniform light distribution and with high light yield. Such a lamp is particularly portable and is advantageous for use in assembly operations in underground mining. The screw socket may be replaced by some other form of connection such as a bayonet fitting. WHAT WE CLAIM IS:

1. A mining lamp comprising a) a light-permeable protection tube closed at both ends with sealing compound and adapted to contain a fluorescent tube; b) a lead for supplying the fluorescent tube with current provided with means for connecting the lamp to an intrinsically safe direct current source, at least part of the lead being embedded in the sealing compound at one end of the protection tube; and c) a chopper for interrupting the current supplied to the fluorescent tube, the chopper also being embedded in the sealing compound at said one end of the protection tube.

14. A combination according to claim 13, wherein the current and voltage limit

ing circuit is adapted to be actuated by inserting a plug into the plug socket.

15. A combination according to claim 13, wherein the current and voltage limiting circuit is adapted to be actuated by means of a switch which can be actuated from outside the housing.

16. A combination according to claim 13, 14 or 15, wherein the housing is a sealing compound within which the cells, the current and the voltage limiting circuit and the plug socket are embedded.

17. The combination of a lamp and a battery substantially as hereinbefore described with reference to, and/or as illustrated in, the accompanying drawing.