Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
  • F21S6/00—Lighting devices intended to be free-standing
  • F21S6/005—Lighting devices intended to be free-standing with a lamp housing maintained at a distance from the floor or ground via a support, e.g. standing lamp for ambient lighting
  • F21S6/007—Lighting devices intended to be free-standing with a lamp housing maintained at a distance from the floor or ground via a support, e.g. standing lamp for ambient lighting for indirect lighting only, e.g. torchiere with reflector bowl directed towards ceiling
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
  • F21V25/00—Safety devices structurally associated with lighting devices
  • F21V25/10—Safety devices structurally associated with lighting devices coming into action when lighting device is overloaded, e.g. thermal switch
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
  • F21V25/00—Safety devices structurally associated with lighting devices
  • F21V25/12—Flameproof or explosion-proof arrangements

Definitions

• This invention relates to the field of- halogen torchiere lamps and, more particularly, to safety measures for halogen torchiere lamps having horizontally installed bulbs.
• a typical halogen torchiere lamp has an upward-facing lampshade mounted atop a long, upright stem. Most halogen torchiere lamps for home use have a double-ended, horizontally- mounted halogen bulb set within the lampshade.
• a horizontal halogen bulb 4 is mounted on two larnpholders 3, which are installed on two tabs of a U-shaped bracket 2.
• the bracket 2 is, in turn, mounted on the threaded screw brushing 7 of the stem about its central hole. Two mounting tabs of U-shaped bracket 2 are used to install lampholder 3/reflector 26 assembly beneath bulb 4.
• the double-ended halogen bulb 4 is installed in the larnpholders 3 above reflector 26.
• a half cylindrical glass shield 6 is held in position above the bulb 4 by means of two clips 17,18 to prevent contact by the user with the bulb 4 and to guard against the scattering of particles of bulb 4, should it shatter.
• halogen torchiere lamps for home use utilize a 300 watt halogen bulb mounted within the lampshade.
• the 300 watt halogen bulb generates intense heat, and generally has a working temperature of 500°-600°C.
• the upwardly-directed heat is further intensified by the upward reflection of the bulb's heat and luminescence by the top surface of reflector 26 and by the inside of lampshade 10.
• the half-cylindrical glass bulb shield 6, while intended to protect the bulb 4 unfortunately impedes air circulation and thereby contributes to the heat surrounding the bulb 4.
• window treatments or other materials such as clothing, paper or toys, all of which are often made from flammable materials, could cover the upwardly-facing lampshade opening or could otherwise contact or come close enough to shield 6, which is almost as hot as the bulb 4 itself and has a working temperature of 400-500°C, such that such materials would then be caused to ignite from the intense heat of the shield 6 and of its immediately surrounding area.
• shield 6 which is almost as hot as the bulb 4 itself and has a working temperature of 400-500°C
• the insulation of the wiring system (including the lead wire, the terminal block, the wire connector and the sleeving) in the area surrounding the reflector 26 and U-shaped bracket 2 and touching same will be degraded such that a fire caused by a short-circuit will take place.
• the material that covers the lamp is flammable, i.e., it has a temperature limit of 200°C, it will become charred and will then ignite due to the intense heat above the bulb.
• a flat grid formed by plurality of parallel wires with a circular border is installed flush with or slightly below the opening of the shade in order to prevent flammable materials from contacting the glass shield.
• a temperature sensor is installed within the lampshade on the reflector, near the midpoint of the bulb. When the lampshade opening is covered by any material, the upper portion of the lampshade acts as a greenhouse, i.e., the ambient temperature of the upper portion rises gradually.
• the temperature sensor located in the path of hot air flow passes the temperature sensed to a connected shut-off circuit. When the ambient temperature inside the covered lampshade exceeds a particular preset threshold value, the power circuit of the lamp is automatically triggered to shut the lamp off before the high temperature causes a fire.
• Another embodiment of the invention utilizes the dimmer circuit that is already present in many halogen torchiere lamps.
• a control circuit with a thermistor circuit is coupled to the dimmer circuit within the prior art circuitry inside the halogen lamp for automatically adjusting the output power.
• the power of the lamp will be reduced, rather than shut off, so that the bulb shines less brightly and thereby emits less heat.
• the ambient temperature within the lamp is thereby maintained at a safe level, and the lamp continues to provide light for the user.
• this invention avoids fires being caused by the lampshade opening being unintentionally covered by any kind of material.
• it is one object of this invention is to provide a safety construction for traditional halogen torchiere lamps to prevent a fire that could occur when the lampshade is covered by any material .
• FIG. 1 is a partial cross-sectional view of the head of a traditional halogen torchiere lamp head
• FIG. 2 is a side elevational view of a traditional halogen torchiere lampshade equipped with prior art lampshade guard;
• FIG. 3 is a cross-sectional view of a halogen torchiere lampshade equipped with the invention, showing the convective current air flow when the lampshade opening is covered by any material;
• FIG. 3a is a cross-sectional view of a halogen torchiere lampshade equipped with the invention, showing the temperature gradient when the lampshade opening is covered by a wooden plate;
• FIG. 4 is a top perspective view of a first embodiment of this invention, showing the location of each component;
• FIG. 5 is a top perspective view of the sensor used in.FIG. 4, showing the thermostat and the mask;
• FIG. 6 is the circuit diagram of a first embodiment of this invention.
• FIG. 7 is the circuit diagram of a second embodiment of this invention.
• FIG. 8 is the circuit diagram of a third embodiment of this invention.
• FIG. 9 is a schematic diagram of the third embodiment of the invention .
• a prior art halogen torchiere lamp typically has a double-ended, horizontally-mounted bulb 4 set within the lampshade 10.
• Horizontal halogen bulb 4 is supported within lampshade 10 by two lampholders 3, having appropriate lead wires (not shown) and is mounted on a U-shaped bracket 2.
• Bracket 2 is installed on the threaded screw brushing 7 of stem 11 about its central hole.
• an optional prior art reflector assembly (not shown) , which has the shape of a wide, low-profile rectangular or trapezoidal raised section for reflecting light from bulb 4 upward and out of lampshade 10, may be mounted beneath bulb 4.
• the double-ended halogen bulb 4 is installed in the lampholders 3 above the reflector assembly 26.
• a half cylindrical glass shield 6 is held in position above bulb 4 by means of two clips 17,18 that attach to lampholders 3 in order to prevent contact by the user with bulb 12 and to guard against scattered particles of bulb 4, should it shatter.
• prior art halogen torchiere lamps often also include a wire or mesh grid, referred to as guard 13, as shown in FIG. 2, that forms a dome-like convex projection above lampshade 10.
• guard 13 When a flammable fabric falls over lampshade 10, grid 13 provides a large air space "buffer zone" above bulb 4 in order to prevent fires from being caused by the flammable material being in too close proximity to heated bulb 4. As discussed, the profile of the torchiere lamp is thereby degraded.
• a fire may be caused even in the event that the air space provided by guard 13 is sufficient to enable the halogen torchiere lamp to pass the above-discussed UL safety test; this may occur if the flammable fabric that is unintentionally placed over lampshade 10 is thicker, denser or allows less air filtration than the two layers of cheese-cloth used in the UL safety test. This is due to the fact that the ambient temperature within the limited air space inside lampshade 10 between bulb 4 and grid 13, which is being continuously heated by bulb 4, may eventually rise to the temperature at which the flammable material combusts.
• FIGS. 3 and 4 An embodiment of the invention"- is shown in FIGS. 3 and 4.
• the lampshade opening is shown covered by any material 8, such as a window treatment, clothing or a flammable object such as a toy, which rests on grid 13.
• Bulb 4 heats its surrounding air and produces the convection air current shown by the arrows 24.
• a slot 22 is cut through reflector 26 on each side of bulb 4 in order to assist in forming the convective current loop.
• the shapes and the dimensions of slots 22 can be determined by hydrokinetics .
• One slot is located between bulb 4 and sensor 25, as shown in FIG. 4, and the other slot is located on the other side of bulb 4, opposite sensor 25.
• the components of the wiring system above/beneath reflector 26/U-shaped bracket 2 which components have safety temperature limits as follows: wire connector-150°C; sleeved power cord-150°C; lead wire-200°C; terminal block-150°C; and nylon binder- °C, may be touching reflector 26 or bracket 2, perhaps causing their temperatures to rise beyond their respective safety limits. Thus, the insulation of the wiring system will be degraded and a fire caused by short-circuit will take place.
• sensor 25 should be no higher than bulb 4 in order to prevent a shadow from being cast by sensor 25 outside lampshade 10.
• Sensor 25 may consist of a thermostat 31 as shown in FIG. 5.
• Sensor 25 may be fit into any halogen torchiere lamp using the simplest control circuit, as shown in FIGS. 6 and 7.
• Sensor 25 may also consist of a thermistor 34, which has a more complicated control circuit diagram, as shown in FIG. 8.
• the internal lampshade arrangement in each embodiment has the same configuration as shown in FIG. 3 except for the electrical function of sensor 25.
• FIG. 4 shows lampshade guard 13 having a circular shape.
• any border shape of guard 13 can be used, such as rectangular, square, elliptical, etc.
• Lampshade guard 13 should be formed of wires that extend across the top of the lampshade iri such a way as not to cast shadows.
• Several parallel wires extend across the lampshade in a direction that is not co-planar with, but is preferably perpendicular to, that of halogen bulb 4 and in a convex profile. Thus, because the wires are not co-planar with the bulb, shadows are not cast.
• sensor 25 comprises a thermostat 31, as shown in the controlling circuit diagram of FIG. 6.
• Thermostat 31 is used because automatically resetting thermostats are common and are widely used in primary circuits for automatically breaking/connecting the circuit based on ambient temperature. If thermostat 31 is chosen with its current rating, say 1 A, 2 A, etc., thermostat 31 can replace the original fuse used in the lamp.
• FIG. 5 shows that the sensor 25 of this invention consists of two main parts, the first of which is the automatically-resetting thermostat 31 and the second of which is a half-cylindrical mask 30. It is preferred that mask 30 extend slightly higher in height than thermostat 31 in order to prevent direct illumination, of the thermostat body 31 by bulb 4, as this would cause thermostat 31 to read an artificially high temperature.
• the air buffer space formed between mask 30 and thermostat 31 is intended to allow for air flow to prevent the temperature sensed by thermostat 31 from being affected by the proximity to mask 30, which is illuminated directly by bulb 4.
• Mask 30 is preferably formed of an aluminum sheet, the thickness of which has no limit but in normal use is preferably 0.4 mm to 0.7 mm.
• Mask 30 can be attached to thermostat 31 by first being clipped to the thermostat 31 and then being glued to it by epoxy resin.
• Mask 30 can the ⁇ j be fixed on reflector 26 by its extended portion, which has an eyelet 27 through which a rivet is passed to form a mechanical attachment. Other means of attachment can also be used.
• Insulating sleeves should be used on the leads of thermostat 31 according to safety requirements. For a halogen torchiere lamp with a 300 watt bulb and a lampshade opening diameter of twelve inches, a 130°C rating thermostat 31 is used.
• thermostat 31 when the lamp is turned ON and any material covers the lampshade opening, thermostat 31 will disconnect the electrical power to the bulb before the covering material reaches 250°C and ignites. In this case, the temperature of the central wire grid is set to reach approximate maximum temperatures of 150°C uncovered and 250°C covered, respectively.
• thermostat 31 In normal use, when the halogen torchiere lamp is turned ON at its full output wattage (generally 300 watts) , if the shade opening is covered by any material, thermostat 31 will automatically cut off power to bulb 4 within approximately twenty seconds, as the maximum allowed temperature is quickly achieved. Then, after approximately twenty minutes, the cooled halogen torchiere lamp will turn back ON. Since the life expectancy of the thermostat is approximately 10,000 ON/OFF cycles, the lifetime of this inventive device is acceptable .
• the halogen torchiere lamp is equipped with an electronic dimmer, and thermostat 31 can be put in series with said dimmer so that the dimmer will automatically adjust the output power.
• the output of the halogen lamp is 300 watts.
• the resulting ON/OFF cycle will be the same as .that discussed above with respect to the first embodiment.
• the lamp's output will be less than 300 watts and the result will be safer than that mentioned in the first embodiment.
• thermostat 31 In this lower power position, for example, 150 watts, thermostat 31 will not act to shut the power off since the ambient temperature within lampshade 10 does not exceed the action point of the thermostat 31. Thus, because the ambient temperature within lampshade 10 does not get too high, the flammable material will not combust.
• a resistor Rp packed by 0.2 mm thick insulation taper and rated 2 K Ohm/5 Watt can be connected in parallel to thermostat 31, as shown by the wiring with dotted lines in both FIGS . 6 and 7.
• Resistor Rp is bound to thermostat 31 by suitable means. Therefore, once thermostat 31 is OFF, electric current will pass through resistor Rp, and the heat produced by resistor Rp will keep thermostat 31 on its OFF condition until the user unplugs the lamp. After the lamp is unplugged, there will be no current in resistor Rp, and the temperature of resistor Rp as well as thermostat 31 will revert thermostat 31 to the ON position.
• this additional safety feature can be accomplished simply by using a thermostat having the property that, once it is OFF, the lamp must be unplugged in order to reset it.
• resistor Rp can be omitted in favor of this specific type of thermostat.
• FIG. 8 shows the circuit diagram of the third embodiment of this invention.
• sensor 25 consists of a thermistor 34, preferably SDT1000 rating.
• a photocell preferably S740 rating, is installed in order to supply DC current to thermistor 34 so that there is sufficient bias to control the transistor, preferably MJE 13003, which in turn controls the triac, preferably Q4010L .
• Installation of thermistor 34 onto mask 30 is similar to installation of thermostat 31 onto mask 30, as discussed above.
• Photocell 15 can be installed in a location within the lampshade which is cooler, for example, at a location farther from the bulb than the location of thermistor 34.
• capacitor Cl is preferably rated 4.7 ⁇ F/16 V
• capacitor C2 is preferably rated 0.068 ⁇ F/250 V
• rheostat Rl is rated 1 Ohm.
• sensor 25 senses that the ambient temperature within lampshade 10 exceeds a predetermined value and either simply cuts off the power supply to the lamp and thereby shuts the lamp OFF or utilizes the dimmer to reduce the power output of bulb 4.
• thermistor 34 senses the ambient temperature within lampshade 10 and thus varies the bias on the gate of the transistor. The resistance (R c-e) of said transistor will continuously be changed accordingly and, therefore, the charging current on the left side of the trigger diode will be controlled accordingly. This in turn controls the dimness degree of the triac.
• Photocell 15 can be arranged so that, when bulb 4 is in its half output condition, the output of photocell 15 can still make the transistor work.
• Thermistor 34 can be packed with several layers of sleeves in order to increase the thermal capacity of the whole sensor 25. That is, when the ambient temperature within the lampshade reaches 130°C, the thermal gradient of the s-leeve layers must be at least 10°C. Then, thermistor 34 senses a temperature of 120°C and the transistor functions to dim bulb 4 slightly. But, since the sleeve layers still pass some thermal energy to thermistor 34, bulb 4 will be dimmed further. Even if bulb 4 is completely turned off, the sleeve layers will maintain the bulb's temperature at no less than 120°C for at least ten minutes. This arrangement prevents the length of the period of the ON/OFF cycle of the bulb 4 from being too short, such as less than ten minutes.
• thermostat/thermistor can be used in all embodiments of this invention, especially if a low-rating (say, 120°C or less) thermostat/thermistor is used. In doing so, mask 30 can be replaced by an enclosure of any suitable shape. This method is used especially when thermostat 31/thermistor 34 has a lower temperature rating, such as 120°C, instead of the original 130°C rating.
• switch SW1 , switch SW2 and the potentiometer VR are coaxial.
• SW1 When the common axis is turned clockwise, SW1 is ON first, the potentiometer is then from the low voltage to the high voltage, and SW2 is ON. Since initially bulb 4 (preferably 300 watt and 230 volt) is dim, the photocell does not have enough output to push the transistor. Thus, the triac will not work and bulb 4 will remain dim. Therefore, SW2 must be always in its ON position in order to make the whole circuit a traditional one, since the two leads of the bridge B (4 x 1N4007) are short-circuited by SW2.
• SW2 When the common axis is turned to the mid point, for example, the half output of bulb 4, SW2 is arranged OFF since now the brightness of bulb 4 has enough energy to push whole inventive circuit to work.
• SW2 can be replaced by a separate switch such as a push-button switch, rock switch or a dip switch, etc.
• SW1 can also be separate from the potentiometer.
• rock switches SW1 and SW2 together with the potentiometer VR are all installed in the stem of the lamp.
• One button PN is used to control all three. When button PN is pushed downward, knob El pushes ON the SW1 first. When button PN continues further down and reaches its middle point, knob E2 pushes the SW2 OFF. If button PN is now pushed upward, SW2 will be pushed ON first, after which SW1 will be pushed OFF. Such an arrangement is preferred when a sliding potentiometer is used.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Arrangement Of Elements, Cooling, Sealing, Or The Like Of Lighting Devices (AREA)
• Non-Portable Lighting Devices Or Systems Thereof (AREA)
• Circuit Arrangement For Electric Light Sources In General (AREA)

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• 1997
  • 1997-10-08 WO PCT/US1997/017906 patent/WO1998016942A1/en not_active Application Discontinuation
  • 1997-10-08 EP EP97909964A patent/EP0873572A1/de not_active Withdrawn

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