Safety mechanism for lamps

A protection device for vertically standing lamps devices is described. The protection device consists of a switch or other means of interrupting the electrical current in case of a fall. The preferred embodiment of the invention is a normally open switch installed at the base of the lamp. This switch is closed by the action of lamp's own weight.

BACKGROUND
 1. Field of Invention
 Vertical upstanding lamps, such as the one shown in FIG. 1, have become
 very popular in recent years. In spite of such popularity these lamps
 present a fire hazard when in presence of flammable objects. The reasons
 for this high fire risk are the following:
 First, the temperature of the lamp, usually a 300 to 600 watt quartz lamp,
 is very high;
 and second, the center of gravity of these modern lamp designs is very high
 which makes the lamp very unstable and prone to falling.
 The combination of high temperatures plus poor stability increases the
 probability that the light bulb may come into contact with a flammable
 surface, such as carpet, which in turn can ignite a fire.
 While, in this patent application a safety mechanism as applied to a
 vertically standing quartz lamp as the preferred embodiment of the
 invention is described, the safety mechanism is also applicable to any
 type of lamp which poses a fire hazard when it falls.
 2. Description of Prior Art
 The idea of interrupting the electrical current to a device has been
 successfully applied to other hazardous conditions, which arise from the
 operation of electric devices. In U.S. Pat. No. 5,576,683, Rose describes
 a Thermostat with thermal insulator for protection against overheating in
 which the electrical current is cut after a threshold temperature has been
 reached. In U.S. Pat. No. 4,973,936, Dimpault and Darcy describe a thermal
 switch for short circuit protection of batteries, which cuts the battery
 current in the event of a short circuit.
 In general, the concept of a circuit breaker which interrupts the
 electrical current when a hazardous situation arises (machine is blocked,
 the current is excessive, the temperature is above a threshold) has been
 used in the referred patents and in other inventions. This idea is also of
 common use in the protection of electrical installations in houses and
 other buildings.
 In the case of vertically standing lamps, the protection against the fire
 hazard in case of a fall has not been addressed using the general idea of
 interrupting the electric current to remove the source of heat. In order
 to increase the safety of vertically standing lamps such as the one shown
 in FIG. 1, these lamps come assembled with a protective grid on the light
 bulb as shown in FIG. 2. This grid can be made either of plastic, metal or
 other material. The purpose of the grid is to prevent the light bulb from
 coming directly into contact with the flammable materials in case of a
 fall. The grid effectively reduces the fire hazard by isolating the source
 of heat from the flammable materials rather than eliminating the source of
 heat. Because the grid only isolates the source of heat rather than
 eliminating it, there is still a certain degree of risk since the grid
 becomes hot and may ignite a highly flammable material such as paper.
 There have been many incidents in which a lamp, such as the one described
 in this application, has caused a fire when it fell on top of a flammable
 surface.
 OBJECT OF THE INVENTION
 It is the object of this invention to provide a mechanism to turn off the
 lamp when the lamp falls. By removing the source of heat, i.e. the lamp
 turned on, in case of a fall, the risk of starting a fire will be almost
 eliminated.

DETAILED DESCRIPTION OF THE INVENTION
 The general functioning principle of the invention is to connect a switch
 or other type of circuit breaker in series will all other switches and
 dimmers, which form the lamp's electrical circuit. The purpose of this
 switch is to interrupt the current supply to the lamp when the lamp is not
 standing up-right.
 FIG. 3 contains a circuit diagram of a lamp without the extra protection
 device. The utility source of electricity is connected to the lamp through
 the plug, number 1, in series with wire, number 2, (the hot wire), which
 is connected in series with a main switch, number 3, to an optional
 dimmer, number 4. The dimmer circuit is then connected to the lamp bulb,
 number 5, by wire, number 6, (the return wire). To close the circuit, the
 other terminal of the lamp bulb is connected back to the plug by wire,
 number 7 (the neutral wire).
 The switch, number 4, and the dimmer, number 5, may be provided in a
 combination switch/dimmer assembly. This combination does not affect the
 working principle of the lamp.
 Since the lamp circuit is a series circuit, there are other possible
 permutations of the lamp bulb-dimmer-switch-plug series connection, which
 would provide a working embodiment of the lamp.
 FIG. 4 contains a circuit diagram of the preferred embodiment of the
 invention. In this circuit, the plug, number 1, is connected in series
 with the hot wire, number 2; in series with the main switch, number 3, and
 the dimmer, number 4. The additional protection device, number 8, is
 connected in series with the dimmer number 4 by an extra wire number 9 and
 to the lamp bulb, number 5 by wire number 6 (the return wire). To close
 the circuit, the other terminal of the lamp bulb is connected back to the
 plug by wire, number 7 (the neutral wire). The function of the additional
 protection device, number 8, is to first, detect that the lamp is not in
 the vertical position, and second to open the circuit when the off
 vertical condition is detected.
 As in the prior art, the switch, number 4, and the dimmer, number 5, may be
 provided in a combination switch/dimmer assembly. This combination does
 not affect the working principle of the lamp. This is also the reason why
 the wire between the switch and the dimmer is not labeled in the figures.
 The protection device, number 8, can be implemented as a switch, which
 opens the circuit in case of a fall. Other protection devices, such as a
 position sensor and a relay can be used provided that they interrupt the
 current when the lamp is not in the upright position.
 In the case of a lamp fall, the additional protection device will open the
 series circuit and will turn off the lamp. By turning the lamp off, the
 additional protection device will remove the source of heat which will, in
 turn, greatly reduce the fire hazard since the only heat source left will
 be the residual heat in the lamp's surfaces.
 Similarly to the prior art, the series combination of lamp
 bulb-dimmer-switch-plug-protection device-plug can have many series
 permutations, which will provide a working embodiment of the invention.
 Also, similarly to the prior art, the main switch-dimmer or the main
 switch-dimmer-protection switch may be supplied in a single assembly
 without affecting the working principle of the invention.
 The preferred embodiment of protection device (number 8 in FIG. 4) is a
 switch installed at the base of the lamp as shown in FIG. 5. The switch,
 number 10, is a switch of the normally open type. This switch is installed
 at the base of the lamp, number 11, in such a way that it is closed when
 the lamp is standing in the vertical position by action of the lamp's own
 weight against the floor, number 12. When the lamp is not standing in the
 vertical position, the normally open switch will no longer be closed by
 the action of the lamp's weight and therefore will interrupt the supply of
 current to the lamp turning the lamp off. This is the simplest embodiment
 of the invention since both functions of position sensing and circuit
 opening are implemented by the switch at the lamp's base.
 In another embodiment of the invention, the protection device can be
 implemented by a relay in combination with a position sensor, which
 detects that the lamp is not standing vertically. The position can be
 implemented by a switch at the base of the lamp or by a position sensitive
 device such as a mercury switch.
 FIG. 6 shows a possible embodiment of the protection device as implemented
 by a position sensor and a normally closed relay. The principle of
 operation is very similar to the preferred embodiment as follows: First,
 the utility power is connected to the circuit via the plug, number 1. This
 is connected in series with the hot wire, number 2, in series with the
 main switch, number 3, in series with the optional dimmer assembly, number
 4. This combination is in series with the relay contacts, number 13, which
 in this case embody the circuit opening function of the protection device.
 For this embodiment of the invention, we assume that the relay is of the
 normally closed type. The relay contacts, number 13, are then connected to
 the lamp bulb, number 5, via the return wire number 6. The circuit is then
 closed by the neutral wire, number 7. This series circuit (the main
 circuit) is connected in parallel with the circuit formed by the
 plug/power source, number 1, the hot wire, number 2, the main switch,
 number 3, the relay coil, number 14 and the position sensor number 15.
 Assuming that the position sensor closes the circuit formed by elements 1,
 2, 3, 14 and 15 (the control circuit) when the lamp falls, and also
 assuming that the main switch, number 3 is closed (the lamp is on), the
 relay contacts, number 13 will be open because the coil, number 14 is
 energized. By this action of the relay, the circuit formed by elements 1,
 2, 3, 4, 5, 6, 7 and 13 (the main circuit) will be open, effectively
 turning the lamp off and removing the source of heat. In this embodiment
 of the invention, the position sensor can be implemented by a mercury
 switch, which detects when the lamp is not vertical or by a switch at the
 lamp's base. Both, the base switch or the mercury switch would energize
 the coil number 14 when the lamp falls. A switch installed at the base of
 the lamp can also be used as a position sensor to energize the relay
 instead of directly opening the main circuit as in the preferred
 embodiment of the invention.
 There are other combinations that also provide a working embodiment of the
 invention. For example, the relay contacts, number 13, can be of the
 normally open type combined with a position sensor which closes the
 circuit 1, 2, 3, 14, 15 (the control circuit) only when the lamp is in the
 vertical position. Therefore, in case of a fall, the position sensor would
 open the control circuit, which in turn will de-energize the relay coil
 14, which would in turn open the main circuit and turn the lamp off.
 It must be noted that the main switch number 3, need not be part of the
 control circuit in order to have a working embodiment of the invention.
 The switch circuit is also placed as part of the control circuit in order
 to avoid the unnecessary energizing of the relay coil when the lamp is
 turned off by action of the main switch.
 It must also be noted that since the main and the control circuits
 individually are series connections of various elements, therefore there
 are other permutations of the elements of each circuit that provide a
 working embodiment of the invention.
 ADVANTAGES OF THIS INVENTION
 The main advantage of this invention is increased safety, when this
 invention is compared to the prior art (placing a grid on top of the lamp
 to increase safety). This invention eliminates the source of heat by
 turning the lamp off. The prior art simply isolates the source of heat but
 does not eliminate it. By turning the lamp off, in the case of a fall,
 this invention improves the safety of all lamps regardless of whether a
 safety grid is used or not.
 A secondary advantage of this invention is the reduction of cost since the
 safety grid becomes unnecessary, and ease of maintenance since it becomes
 easier to change a light bulb once the safety grid has been eliminated.
 CONCLUSION
 The invention improves the safety of any vertically standing electrical
 device, which is prone to a hazard in case of a fall.