BACKGROUND OF THE INVENTION
1. TECHNICAL FIELD OF THE INVENTION
[001] The present invention relates generally to the field of illumination and, more particularly to a solid state lighting source such as a light-emitting diode ("LED") device that provides for directed, focused illumination of targeted space that requires proper constant visibility for long hours for action oriented industrial activities. LED based illumination device of this invention can be customized for a variety of applications, such as a battery of stitching machines employed in large leather, cotton or any other fabric garment production lines.
[002] Illumination of homes, offices and working places in industry is a normal requirement and building infrastructures are required to make appropriate provision for the same. Many industrial and commercial activities dependent on human intervention often require additional directed and focused illumination of certain key components of the appliances and working places to enable the workers to train their eyes on specific spots. Some examples of these situations are Typists typing the documents, tailors stitching the fabrics, surgeons performing surgery and scientists working with microscopes. Often such additional lightings are also required to provide necessary back up to take care of emergency situations involving power failures where an interior or exterior area is rendered without light.
[003] Maximizing productivity by improving the working environment is a cherished goal of all economies of the world today and lighting constitutes an important element of the work place especially when it involves the skilled workers handling precision jobs and various crafts such as fashion and utility garments, embroidery etc. It is often necessary to create lighting for such working places that conform to international standards of recommended luminosity with controlled glare and heat generated as a result of extra lighting. The increasing demand of power generation and its perennial shortage with imminent crisis of global warming leads us to design a lighting source that is as energy efficient as possible with low heat generation thereby cutting down on refrigeration and air conditioning costs.
[004] Consideration of consumer comfort brings us to maximizing performance versus cost, low maintenance, and low risk of fire or electrical shock. There are numerous situations where in absence of any dedicated in-built lighting source for specific objects in industrial appliances, additional lighting of the order of several magnitudes in excess of normal requirement is provided to keep the key spots duly illuminated. These necessities in production areas not only raise the cost of energy several folds but also pose considerable environmental hazards due to extra electrical wiring and heat generation from the use of excess electrical power. Application of next generation lighting source such as LED as

disclosed in this invention is also aimed at containing the carbon emissions from the future industrial activities.
[005] In addition to the circumstances described above, there are numerous instances where a lightweight illumination device of appropriate lux that is handy, easily transportable and capable of being fixed without any external help is required by independent users in their homes or offices at least until such times that the device described herein becomes the part of OEM by the manufacturers of such machines.
[006] Keeping in view of these requirements and a deficiency existing in the prior art, a compact, lightweight and smart illumination device has now been developed and disclosed herein with a very long working life minimizing the need for replacement providing highly conducive cool spotlights without any environmental risks.
2. BACKGROUND AND THE PRIOR ART
[007] Room lighting in homes and on commercial premises is generally found to be inadequate for sufficiently illuminating the work field around a sewing machine and, particularly, within the area of the needle. Devices are known to the prior art by which the work field can be illuminated directly. In many earlier attempts, incandescent light bulbs are arranged for this purpose on the head of sewing machine
[008] One of the earliest patents known to prior art is US 1083020 of 1913 that employs a brass tube bent into a required shape and provided with a number of clamps to hold it with the body of the machine from different sides. The terminal end of brass tube supports a bulb with cover that directs the concentrated light in the working area.
[009] US Patent No. 2447833 describes an arrangement wherein an incandescent lamp is mounted on the rear arm of the sewing machine. While this type of arrangement is capable of illuminating the work area, it brings with it a number practical difficulties and drawbacks. US Patent No. 2277972 describes a yet another arrangement using incandescent bulb specifically for cup-feed sewing machines. A similar lighting device is also described in U.S. Pat. No. 4,413,310, wherein an incandescent lamp is arranged with vertical adjustability along the head of the needle and presser foot bars laterally.
[010] US Patent No. 2677042 provides for an arrangement using a reflector and lens on the sewing machine arm in the front itself in a manner that allows replacement of bulb and servicing.

[011] US Patent No. 4747024 uses electroluminescent light positioned directly beneath the foot whereby a work piece is illuminated from its underside. The object of this invention is primarily to maintain the alignment of work pieces rather than the lighting per say. Nevertheless, it addresses the need for lighting in the work area while sewing machine is in use.
[012] A lighting device is also known to the prior art from Federal Republic of Germany patent application No. 3525698, which comprises two rod-shaped luminous elements, which are arranged on the side of the needle or presser foot bar. While it is possible with this tandem arrangement to realize illumination of the work site, the arrangement poses several difficulties with mounting two luminous elements and their electrical feeds requiring a great deal of space, not otherwise and their proximity to the sewing stock posing the risks of fire and burns on account of inattentiveness.
[013] DE8703621 and US4841415 with priority date of the former describe a lamp, in which the light is led by light guides from a source to the vicinity of the needle. Drawbacks reside in the illumination of very restricted area around the needle which is barely sufficient for most practical purposes. The light guide itself may interfere with an operator's sewing job.
[014] In a lighting system in US6168284B1, a light is provided on the lower side of the sewing machine arm, illuminating the needle bar and a presser foot rod by constructing a loop over a range of 180°. The lamp used here is preferably a cold-light-cathode fluorescent lamp which is known to radiate a little. While this appears to be radical improvement over previous inventions, it suffers from high production and maintenance cost, spare parts availability etc.
[015] A recent utility patent from China (CN201136961Y) for the illuminating lamp of a sewing machine has used ten LED lamps in a plastic outer casing which is stated to have overcome the problems of shadow in the workspace as encountered in prior art earlier to it. However, our invention is much simpler, handy and quite rugged to last a life time at a fraction of its cost.
[016] CN1749464A provides a set of two LED lights arranged in the sewing machine, one sucked in the abdomen of sewing machine head and the other installed in the abdomen of sewing machine head and with changeable angle. These two lamps light the area below the abdomen of sewing machine head. Obviously, the invention calls for the services of expert technicians to install and service the product.
[017] US6796256 provides sewing machine lighting equipment comprising of series of LEDs on the underside of the sewing machine arm on two sides of the needle bar.

[018] A patent under PCT (WO2005113877A1) from Japanese inventors with equivalent patents in Japan, Korea, China, Germany and US uses lighting array having a plurality of LEDs at appropriate intervals along the arrangement line of a plurality of sewing needles in large industrial machines.
[019] A European patent (EP1348793A2) from German inventors with equivalent patents in Germany, Portugal, Spain, Austria, Taiwan, Japan and USA provides illumination for a sewing machine by a series of LEDs supported in a holder and arranged round the needle bar and needle. The housing has an opening to allow the needle bar and button hole cutter to pass through. Use of series of LEDs do get appropriate level of lux in the work areas as disclosed in this patent is bound to be cumbersome, expensive and impractical in actual situations.
[020] In contrast to the above patents reported in the prior art, the invention disclosed herein uses a single high-powered LED instead of multiple low powered LEDs and other light sources as described in the prior art that provides sufficient illumination of desired objects, such as needle and presser foot in sewing machines used in domestic and commercial environment that has not been attempted before in the manner described herein. The novelty of this invention lies in designing an efficient heat sink for the high powered LED for the desired application, configuration of the system for its industrial application that ensures focused and directed light on the desired object of adequate intensity and in making the complete unit very light-weight, handy and easily transportable which house wives and workers can handle themselves with ease and without any risk.
OBJECT OF INVENTION
[021] The object of this invention is to develop a technically advanced and affordable LED based lighting source at work places that is light weight, transportable and is risk free and environmentally safe in operation to be used as a fixture for industrial and domestic appliances, such as a sewing machine for illumination with bright cool white light.
STATEMENT OF INVENTION
[022] A lighting source based on high powered single LED has been designed and developed that is light weight, transportable and is risk free and environmentally safe in operation which is to be used as a fixture on an industrial appliance to provide reliable source of trouble free illumination with bright cool white light at the work place located at a distance of 20-30 cm from the light with an extended and long life-time of the lamp.

BRIEF SUMMARY OF THE INVENTION
[023] The present invention addresses the needs of dependability, affordability and ease of operation without any risk to human life or environment as described in the previous section and achieves several other advantages by providing a LED based light device comprised of a housing body, an arm that is structured to support a lighting element assembly on one side and a flat mountable disc on the other.
[024] In one embodiment, the light device is configured to be portable and carried or otherwise manipulated by a user with his or her hands. In other embodiment, the mainframe of body of the light device rests on a support surface that is structured to stably support its weight and the other end of the support is so designed with a predetermined diagonal fixating slit that allows it to snugly fit in with the vertical edge of a machine and is affixed firmly to provide light at the pre-determined desired spot.
[025] In one embodiment, the lighting element assembly of the light device may include a high powered light emitting diode (LED) of 1 W or less electrical consumption and a wide viewing angle anywhere between 30-170 degree soldered on to a metal core PCB (MC-PCB) of adequate thickness aluminium layer mounted on to the bottom of a cup shaped metallic body of 2 and 3 cm internal and external diameters respectively made up of extruded aluminium and at a depth of 3 cm from the outer edge that is adapted to provide a spot-light mode of illumination at the object, presser-foot of a sewing machine in this case. In this embodiment, the depth of the LED from the outer edge of the lamp may be configured between 0.5 to 3 cm so that an illumination of the object is achieved between 500 to 1000 lux with a focused directed light at a convenient distance achieving at the same time a base of the illumination cone wider than 20 cm in diameter with no less than 500 lux illumination at the periphery. In this embodiment, MC-PCB consisting of 3 mm or less aluminium layer along with metallic mainframe housing and the support structure acts as an efficient heat sink with temperature of the lamp always below 40° C whereas the temperature at the junctions of LED being about 45° C when in operation at ambient temperature of 30° C .
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING(S)
[026] Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
[027] FIG. 1 illustrates a perspective view of the light device 100 complete with a support structure in accordance with one embodiment of the invention along with cross-sectional views from different sides;

[028] FIG. 2 illustrates a view of the components in the assembly of the light device in accordance with one embodiment of the invention;
[029] FIG. 3 illustrates an inside view of the mainframe body of the lighting source showing the LED and MC-PCB as mounted on the bottom of the cup-shaped body of the light.
[030] FIG. 4 illustrates a view of a light device in an actual application as a fixture on a sewing machine and various specifications of its arrangement and the result of lighting on the object
DETAILED DESCRIPTION OF THE INVENTION
[031] The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.
[032] Referring to FIGS. 1 through 3 collectively, there is illustrated a light device 100 structured in accordance with various embodiments of the invention. In one embodiment, the light device 100 is comprised of a body 110, a support 115 with an arm 120 and a mountable disc 130 that is structured to support a lighting element assembly as shown. In this embodiment, the light device is duly fitted with a 1W LED 135 of wide viewing angle of 120-140 degrees on MC-PCB 150 consisting of a solid 1.5-3 mm thick aluminium layer mounted on to the bottom of the cup-shaped main body 110 preferably made up of extruded aluminium using a good thermal interface material so that entire assembly works as an efficient heat-sink and dissipates heat energy generated at the LED junctions efficiently. In such embodiments, the light device 100 is typically structured to be light-weight and may weigh preferably less than hundred grams.
[033] In one embodiment, the lighting element assembly consisting of LED 135 and the metal core PCB 140 may be fixed in the bottom of the body 110 which has a cavity in a cup like structure with 2 cm and 3 cm internal and external diameters respectively with a bottom thickness of 1 cm and has an internal height of approximately 2 cm with electrical leads 145 emerging out from the bottom near the joint between the body 110 and arm 120 of the support fixed through the soldering joints of LED. In this embodiment, the main body of the lighting element assembly consisting of LED 135 and metal core PCB 140 may be provided with a glass cover 150 affixed preferably with a moisture proof sealant on the edge of glass

cover; the glass cover 150 is then protected with a ring like structure 155 adding 1 cm additional height to the lamp and tightening through internal threads holding the protruded ring like structure with corresponding threads on the outer edge of main body 110..
[034] The body 110 and the upper ring 155 of the light device 100 may be made of structurally strong material having high thermal conductivity, say above 200 watt per meter Kelvin (Wm-1K-1) at 25°C which is a measure of heat transmitted through a unit thickness in a direction normal to a surface of unit area, due to a unit temperature gradient under steady state condition. The support consisting of a disc like structure 115, arm 120 and the mountable disc 130 as an integrated component may as well be made of similar structurally strong material having high thermal conductivity of similar order. For example, lighting device 100 structured in accordance with various embodiments of the invention may consist of the upper ring 155 and the main body 110 made up of extruded aluminium known to have thermal conductivity of 250 watt per meter Kelvin (Wnr1K-1) at 25°C which is long lasting and corrosion resistant and the integrated component comprising of support disc 115, arm 120 and the mountable disc 130 may be made of cast aluminium; both components being made of high conducting aluminium and adjoined together serve as efficient heat sink.
[035] The body 110 together with upper metallic ring 155 and support structure comprising of 115, 120 and 130 of the light device 100 may have large enough exposed surface area to allow the assembly to work as an efficient heat sink. The Table 1 below shows a correlation between heat sink surface area and its temperature co-efficient as per literature report available on internet (Ref: (http://highfields-arc.6te.net/constructors/olcalcs/heatsurf.htm). Thus a heat sink rated at 10 °C/W will get 10°C hotter than the surrounding air when it dissipates 1 Watt of heat. Thus, the total surface area of the light assembly 100 may be more than 25 cm2 so that the lamp would never get hotter than 10°C than the ambient temperature.
Table 1
(Table Removed)
[036] In one embodiment, where the light device is fitted with a 1W LED 135, the total externally exposed surface area of the light assembly 100 comprising of upper metallic ring 155, main body 110 together with support structure comprising of 115, 120 and 130 is, for example, approximately 65 cm2 for the chosen design. In this embodiment the rated capacity of lighting device 100 as a heat-sink is 6.5°C/W, since an external surface area alone excluding the inner surface area of the cup like structure of approx. 65 cm2 has been achieved through innovative design thus ensuring a trouble free life-time of the lamp extending over several decades.
[037]The LED 135 with metal core PCB 140 rest in the bottom of main body 110 at a depth of between 1 cm to 3 cm depending on the required quality, coverage and intensity of incident light on the desired object. The lighting device 100 structured in accordance with various embodiments of the invention for a specific application of illuminating the presser foot of a sewing machine and its surroundings as shown in Fig. 4, for example, was standardized with LED at an optimum depth (A) of 3 cm from the upper edge in a tubular structure of 2 cm diameter with a closed bottom giving focused and directed light of adequate illumination of the object.
[038]The lighting device 100 with LED 135 with other components as described in the embodiments above may be so configured and positioned to give required illumination of an object as per the relationships between various parameters as experimentally determined and shown in the Table 2 below. Thus, the lighting device 100 in actual application may be at a distance of 4"-12" (10 cm - 30 cm) from an object to achieve an illumination ranging between 350 -1900 lux where its surrounding get illuminated ranging between 170 -1300 in an area of diameter ranging between 6.5 to 16 inches.
Table 2

(Table Removed)
[039] Example: Referring to FIG. 4, the lighting device 100 structured in accordance with various embodiments of the invention for a specific application of illuminating the presser foot of a sewing machine is thus positioned at distance (B) of 20 cm from the object to achieve an illumination of 1000 lux at the centre and of up to 500 lux on the periphery of illumination circle of a diameter (C) of 25 cm.
[040] In the above embodiment, the light device comprising an LED 135 fixed in a cup shaped metallic body 110, attached to another metallic support 115 with an arm 120 and having a mountable disc 130 at the other end with an engineered and predetermined diagonal fixating slit 160 that is adapted to allow the body of the lighting device projected outward and inclined at an angle of 120° from the vertical edge of the machine on which mounting disc is fixed through a screw in the hole provided for the purpose. In this embodiment, the lighting device in the example shown in FIG. 4 faces directly the presser-foot of the sewing machine at a distance of 15 cm providing maximum illumination on it with a circle of white t of approximately 20 cm diameter around it.
[041] Another embodiment of the invention is directed to the method of operating the lighting device. Since the LED chosen for the purpose of illuminating an object of the sewing machine works optimally at 3.5 volts providing adequate light energy, a constant and a reliable source of electrical power is a pre-requisite for the invention to work successfully. In this embodiment, therefore, a constant power supply of 3 volts at 330 - 350 mA is provided through a standard adaptor. This low voltage in the working area poses no risk of electrical shock and is absolutely safe.

We claim:
1. A lighting device comprising:
a. a housing;
b. a light emitting diode (LED) with a metal core PCB of 1.5 - 3 mm Aluminium layer as a base for
LED located in the housing;
c. a support structure of adequate structural strength for holding the housing that comprises of an
arm with two discs on either side, one for affixing the base of the housing and the other for
affixing the fixture on to the appliance having desired object requiring illumination
2. The lighting device as defined in claim 1, where the lighting source is limited to high powered LED of 1 W with an emitter angle between 30-170° fitted on to MC-PCB of 1.5-3 mm aluminium base.
3. The lighting device as defined in claim 1, where the housing and support structure including the metallic cover are made up of aluminium or its alloys or any other metal having thermal conductivity between 200 - 300 Wm 1 K 1 and where the total externally exposed surface area is in excess of 25 cm2.
4. The lighting device as defined in claims 1 - 3, where the mountable disc is having a diagonal fixating slit-on it allowing the fixture not to slide accidentally and stay snugly fitted on to the vertical edge of an appliance. The mountable disc may be further customised by providing extra grooves or wholes depending on the exact geometry of the machined requiring device to be attached.
5. The lighting device as defined in claims 1 - 3, where the LED is located at a depth of 0.5 - 3 cm in the cavity of a cup shaped housing of lighting device.
6. The lighting device as defined in claims 1 - 5 and fixed on to a sewing machine or any other appliance of industrial use, wherein the distance of the lighting source and the presser-foot, needle bar or any other targeted object is between 10 - 30 cm and the luminosity of the working area is between 170-1900 lux.
7. The lighting device substantially as herein described and illustrated in the figures of accompanying drawings wherein the device is employed as a mountable spotlight on any industrial device that requires focused and directed illumination.