The present invention relates to replaceable LED (Light Emitting Diode) based lamps and in particular to replaceable LED system which would be shock and vibration resistant unbreakable and also adapted to selectively transform the unidirectional glow of the LEDs into a more uniform glow for better visual appeal and its wide scale advantageous use/application. The LED system of the invention thus avoids the problems of its fragility and loose operative connections and importantly also the inherent limitation of LEDs in generating unidirectional glow / illumination and thereby favour a more comfortable / attractive wider uniform visual glow / illumination from LEDs even in directions other than the direction of installation of the LED. The LED system of the invention is suitable for use in domestic applications such as general lighting, decorative lamp, night lamp etc. apart from wide scale applications as indicator systems in industrial and automotive application such as front and rear indicator lights in vehicles, signal lights in Railways, road traffic and aviation lights and the like.

BACK GROUND ART

Light Emitting Diodes (LED) is a well-known lighting system which is extensively used especially for various indicator / decorative application both for domestic and industrial use.

LEDs require forward operating voltage and current and usually connected in series with current limiting resistor and/or capacitor to control the supply current. It is well known to have LED based lamps as indicators which comprise of polymeric or bakelite based holders which house the LEDs and their operating circuitry of various specifications including those involving capacitor / resistor and rectifier based circuitry. In particular in such conventional LED units, the LEDs / lamps and operating circuitry are loosely inserted within said housing and at the front a filter means is releasably secured to the said holder.

While several varieties of shapes and configurations of such conventional LED based lamps with said loosely inserted operating circuitry and releasable filter of various colours have been proposed it is found that such LED units suffer from certain disadvantages which affected its performance and large scale usage. In particular, in such known LED units, in the instance the LED any component thereof get damaged, the whole unit inclusive of the holder required complete replacement which added to recurring cost of maintaining such unit- Also the front cover / filter was found to be fragile and got damaged on minor impact Moreover, the operative connections being loosely assembled, in case of vibrations / shocks during use the operative connections open up resulting in frequent failure of the unit.

In our co-pending Indian Patent Application No 152/CAL/99 dated 26.02. 99 there is disclosed a replaceable LED lamp comprising:

atleast one LED with / without its operating circuitry moulded / housed with respect to atleast a polymeric base of desired shape and configuration to fit a desired holder having a power supply and operatively connect said LED to said power source.

The above replaceable LED lamp is a replaceable variety and in case of damage to the lamp one can simply replace the lamp without need for disposing the holder unit, which as in conventional incandescent lamps can be continually used. Also the moulding of the operative circuitry and stable securing of the LED ensured proper operating connections even in environments where the lamp was subject to vibrations / shocks during use. Also in accordance with another aspect of the replaceable LED covered in our said earlier co-pending application, there is also proposed a releasable front cover / filter of translucent polymeric material adapted to favour better illumination (lumen output) from the unit.

While the above discussed replaceable LED of our co-pending application takes care of some of the inherent problems of conventional LED units by way of a polymeric housing support, the possible use of translucent polymeric masks as front cover / filter in such systems proposed was directed for better illumination outputs from the unidirectional LEDs used in such systems. In fact not only was the system of our co-pending application based on the need for such selection of such translucent front cover/filter for better lumen output,several other variants to LED units have been proposed over the years to improve upon the unidirectional illumination characteristics of LEDs for varied applications / uses. US 3875456 discloses a multi-color semiconductor lamp comprising a plurality of light emitting diodes disposed close to one another and respectively emitting the light of different colors and a light scattering layer covering these light emitting diodes.

US 5847507 teaches the process and apparatus to produce efficient light emission over a broad portion of the visible spectrum. A lens containing a fluorescent dye is over moulded to a short wavelength light emitter (e.g., a blue LED or laser diode) placed within a reflector cup. The fluorescent dye absorbs atleast a portion of the light emitted by the diode and re-emits light of a second, longer wavelength. Concentration of the dye within the lens can be varied to control the extent of a region within the lens where most of the light is re-emitted so the remaining portion of the lens can focus the light. One can readily and consistently tailor the color of the light emitted from the lens through selection of the number and types of fluorescent dyes added to the lens, and through their relative concentrations. Inventory is reduced and there are no additional steps required when building varied color LEDs. One simply controls the color of the LED being made by selecting from one of several possible fluorescent dye-containing lens epoxies.

WO 0182385 describes a radiation-emitting semiconductor component with a luminescent conversion element, at which the semiconductor body is placed in a recess of the base body. A cup-like area is molded inside of the recess around the semiconductor body, which contains the luminescent conversion element and coats the semiconductor body. The cup-like portion is formed as indentation inside of the recess or as annular border on the base of the recess.

TW 561633 discusses an LED light-emitting device, which is to dispose an LED chip on the substrate. The LED chip is bonded to the electrode circuit through a gold wire, and a resin protection cover containing fluorescent agent is placed on the LED chip. The device is characterized in that: a colored lens is disposed on the LED chip packaged by resin containing fluorescent agent, and the colored lens is made by injection formation of the material mixed by PC plastic material with little amount of ultraviolet light absorbent, yellow master, green master, red master, blue master, etc. The assembly of the structure can convert the light generated from LED into the Sight source having color temperature of 2000 to 5000 DEG K.

US 2004105257 proposes a flashlight having a light-emitting diode light source with first and second leads extending there from, a power source, a power source frame enclosing atleast a portion of the power source; a housing containing the light source and power source, a switch located adjacent the power source and operable to close a circuit including the light source and the power source, and wherein one or all of the following may be included (1) a key ring extension extending from a power source frame or the housing with the key ring extension having an opening whereby an article can be attached to the key ring extension and includes a key ring lock wherein upon exerting a force against the key ring lock, the key ring lock is opened to permit the article to be attached to the key ring extension; (2) the housing is comprised of translucent material; and (3) the housing includes atleast one side cover which is not integral with the housing and the atleast one side cover being selected from anodized aluminum, anodized metal, anodized metal which includes indicia, die struck metal, laser engraved metal, and a side cover having a separate medallion attached thereto.

US 2004105262 propose yet another tight emitting diode chip or chips array mounted on a substrate is surrounded by one or more sidewalls. The wail has an uneven reflecting surface to diverge the light emitted from the LED chip or chip array. The wall may have a triangular cross-section so that the emitted light diverges in all directions. When three double-sided reflecting walls surround three LED panels, the reflected light becomes omni directional hemispherically and can be used in a light bulb.

It would be well apparent from the above state of the art, that while various attempts have been made over the years to improve upon the unidirectional illumination from LED based light sources / units involving translucent covers , lenses, fluorescent dyes, light scattering means, luminescent conversion elements and the use of reflecting walls, it is found that considering the inherent characteristics of unidirectional light output from LED lamps, all such known varieties of LED units have an inherent limitation in that the visual impact of the glow of the LEDs from such units is always best only when viewed from the front since the LEDs only provide light luminance unidirectional in the direction of its installation. None of these prior LED units either solve or attempt to solve the inherent limitation of LED lighting units resulting from the well known characteristics of LEDs to provide only unidirectional fight emission due to which there is clear limitation in achieving uniform multidirectional glow / lighting based on the cost effective LED sources. Most of the attempts had been basically directed to improve upon the illumination from LEDs maintaining its inherent unidirectional light emission characteristics. In fact whenever multidirectional glow is desired from LED based units it has been the usual practice to selectively dispose multiple LEDs in various directions such that the unidirectional glow from the each of the multiple LEDs together cover a wider area which, however, continue to maintain the unidirectional and specific directional glow emanating from the respective LEDs.

So much consideration was given to improve the unidirectional light/lumen output from LED systems that the art preferred thin translucent from covers / filters in conventional LEDs mostly in the form of separately moulded covers / filters which were either permanently or releasable secured to the base / holder unit of the system. Such requirements of thin / translucent covers for better lumen output and the assembling of the units as two components front and rear (holder portion) usually lead to additional problems in terms of loose operative connection and fragile LED systems difficult to handle and use.

The above state of the art thus reveal the problems / limitations associated with LEDs/LED systems in achieving multidirectional uniform glow for a wider and possible attractive view of its glow and also the problems of loose, shock / vibration affecting operative connection of its units / assembling.

OBJECTS OF THE INVENTION

It is thus the basic object of the present invention to provide for a replaceable LED and/or LED chip based system / lamps or other semiconductor light emitting device based system which would be on one hand be shock, vibration resistant and unbreakable on the other hand adapted such that atleast a portion of the externally viewable light emitting portion of the lamp achieves the desired uniform glow / lighting free of any visible unidirectional glow from the LEDs and/or LED chip or other semiconductor light emitting device inside the unit/system.

Another object of the present invention is directed to provide for a replaceable shock, vibration resistant and unbreakable LED and/or LED chip based lamp with uniform external glow / lighting free of any visible unidirectional glow from the LEDs which would be on one hand cost effective and on the other hand simple to manufacture thereby making such LED units available at cost effective prices for a wide range of end use / applications.

Another object of the present invention is directed to a replaceable shock, vibration resistant and unbreakable LED and / or LED chip system with uniform external glow which would avoid the problem of known conventional LED units and incandescent lamps in terms of loose contact due to vibrations / shocks and fragility and consequential breakage due to mishandling and / or accidental impacts.

Another object is directed to provide for replaceable shock, vibration resistant and unbreakable LED/LED chip with uniform external glow, which can be easily used applied and replaced as any conventional incandescent lamp.

Another object of the present invention is directed to provide for replaceable shock, vibration resistant and unbreakable LED / LED chip units or any semiconductor light emitting device with uniform glow property which would on one hand have effective illumination and on the other hand avoid the much desired unwanted unidirectional illuminating effects of LEDs.

A further object of the invention is directed to provide to replaceable shock and vibration resistant LED / LED chip system / unit with uniform glow property and sturdy and non- breakable characteristics for easy and safe handling and large-scale application.

Further object of invention is directed to provide a replaceable shock, vibration resistant and unbreakable LED / LED chip unit with uniform glow property, which can be safely and conveniently used for long life and durable use even in environments of shock and vibration. Further object of present invention is to provide for replaceable shock, vibration resistant and unbreakable LED / LEO chip systems / units which would be simple to manufacture without the need for any expensive/ heavy machinery and/or skilled expertise.

Another object is directed to provide replaceable shock, vibration resistant and unbreakable LED / LED chip lamps with uniform glow property which can be adapted for any desired shape and configuration for varied application / uses as decorative and / or industrial domestic and automotive applications.

SUMMARY OF THE INVENTION

Thus according to one aspect of the present invention there is provided a replaceable LED system with uniform multidirectional glow comprising: -

atleast one LED and / or LED Chip, or any other semiconductor light emitting device with or without operative circuitry permanently and securely held within a shock, vibration resistant and unbreakable polymeric moulding / housing with atleast a part of the externally visible glow able portion selectively obtained to define a substantially uniform glow / illumination on lighting free on any visible unidirectional glow / illumination from the LEDs and / or LED Chip, or any other semiconductor light emitting device inside.

In accordance with another preferred aspect of the present invention there is provided a seamless external surfaced replaceable LED system with uniform multidirectional glow characteristics comprising:

atleast one LED and / or LED chip or any other semiconductor light emitting device, with or without its operative circuitry permanently and securedly held within a shock, vibration resistant and unbreakable polymeric moulding / housing having a seamless external surface with atleast a part of the externally visible glow able portion selectively obtained to define a substantially uniform glow / illumination on lighting free on any visible unidirectional glow / illumination from the LEDs inside.

The above disclosed seamless variety provides for improved aesthetic outlook and surface finish to the product of any shape and configuration which is unique and special as far as LED lighting units are concerned especially the spherical and/or with bulging central portion shaped LED units are concerned.

In the above-disclosed replaceable LED system the selection of the polymeric moulding/housing material is such that on one hand the rear of the unit (non- emitting base portion) is preferably a solid molding of the polymeric material of desired shape and size alongwith the operating circuit and the LED basically targeted at maintaining the LED and the operating units shock and vibration free while the front of the unit (atleast the emitting front portion adapted for the multidirectional glow) is of selective solid polymeric constitution such that same apart from being maintained shock and impact proof is also adapted to importantly avoid the visual unidirectional glow of the LEDs when viewed externally to appear as a multϊ directional soothing and uniform glow of the LED unit.

For the purpose of the invention the selective moulding can be obtained of suitable and selective polymeric material selected from thermosetting polymer like polystyrene, epoxy resin and / or thermoplastic polymers. Importantly, it is found by way of the present invention that the cost-effective polystyrene is best adapted for the purposes of imparting the uniform glow properties to the system. Optionally, the thermosetting polymers can include catalyst / accelerators. Suitable catalysts include Methyl Ethyl Ketone (MEK), Methyl Ethyl Ketone Peroxide (MEKP), Tertiary Butyl Peroxide (TBP), and Benzoyl Peroxide.

The accelerators that can be suitable for use include cobalt salt preferably cobalt octate.

Importantly for the emitting front portion moulding adapted for the selective multidirectional glow it is important to selectively control the selective use of the polymeric material especially polystyrene such that the same achieves the desired shock and impact proof characteristics and also transforms atleast a portion of the visible glowing region of the unit into a multidirectional glow free of any visible unidirectional glow from the LEDs and / or LED chip or any other semiconductor light emitting device. The selection of the polymeric material for such purposes of transforming the unidirectional glow into multi directional uniform glow should be based on the intensity of the LED and / or LED chip or any other semiconductor light emitting device used and required to be internally scattered for a visual more uniform glow from outside. Such controlling of the constitution of the polymeric material for such purposes of internal scattering is achieved by introducing agents such as preferably petroleum product and/or by way of chemically defusing inside the selective and possible use of glass mould especially for seamless variants of the system of the invention proposed hereinbefore. Alternatively, for such purposes the polymeric material can comprise milled filler powder preferably phosphor powder or any other suitable milled powder.

Moreover, for the uniform glow characteristics the moulding / housing can comprises of said selective polymeric moulding material involving variety of colour polymeric materials to add color and variety to the visible uniform glow of system.

In accordance with a preferred aspect the polymeric material covering the LEDs is selectively provided to achieve said uniform external visible glow on lighting avoiding the unidirectional glow from the LEDs.

In accordance with a preferred aspect of the present invention there is provided a replaceable LED system with uniform multidirectional glow characteristics comprising: -

atleast one LED and / or LED chip or any semiconductor light emitting device, with or without operative circuitry permanently and securedly held within a shock, vibration resistant and unbreakable polymeric moulding / housing with atleast a part of the externally visible glowable portion having an external appearance which facilitate substantially uniform glow / illumination on lighting free on any visible unidirectional glow / illumination from the LEDs inside.

For the purposes of such uniformly illuminated external appearance on lighting the polymeric material preferably comprises of suitable agents such as preferably petroleum product more preferably petroleum jelly and / or by way of chemically defusing inside the selective and possible use of glass mould especially for seamless variants of the system of the invention proposed hereinbefore. Alternatively, the polymeric material can comprise milled filler powder preferably phosphor powder or any other suitable milled powder.

In accordance with one aspect the above disclosed replaceable LED unit involving the LED and / or LED chip and operating circuit are together molded involving said selected polymeric materials such that atleast the external visible portion of the lamp when lighted provide for an uniform glow from outside free of any visible unidirectional glow from the LEDs inside.

It would be well apparent that the LED system of the invention therefore is directed to solve the problem of unidirectional light emanating from LED by way of simple cost effective product. Importantly, also apart from uniformity of visible light in all directions the molded housing of the LED and the operating circuit provide for vibration proof and water proof product adapted for more useful and wide application even in vibration and shock environments such as in machines, railways and automobile industry such as the indicator lights and the like requiring uniform external glow.

In accordance with yet another aspect the polymeric molded LED system with uniform glow properties comprise fire retardants characteristics for wider applications of such replaceable LEDs.

In accordance in yet anther aspect the replaceable LED system and in particular the uniform glow region thereof can be further provided with decorative pattern or surface ornamentation to add aesthetic value to the product.

In accordance with yet another aspect of the present invention there is provided a replaceable LED system with uniform multidirectional external glow on lighting comprising: -

atleast one LED and / or LED chip or any semiconductor light emitting device, with or without its operating circuitry permanently and securedly held within said shock, vibration resistant and unbreakable polymeric moulding / housing with only a selective portion of the externally visible portion of the lamp appearing to have a uniform glow on lighting free of any external unidirectional glow of the LED to provide a combination of said uniform glow regions and visible unidirectional LED glowing regions of the external visible portion. In accordance with this embodiment the decorative and aesthetic aspect of the LED system can be further improved upon by way of selectively providing uniformly glowing regions and some regions providing the unidirectional LED glow viewable.

In accordance with another aspect of the present invention there is provided a replaceable LED system with uniform glow on lighting comprising:

any geometric shaped moulding comprising plurality of LEDs and / or LED chip or any semiconductor light emitting device, with or without its operating drcuϊtry permanently, securedly and unbreakably held within a shock, vibration resistant and unbreakable polymeric moulding / housing with atleast a part of externally visible portion of the lamp having a uniform glow region of light free of any visible external unidirectional glow of the LEDs.

In accordance with another aspect of the present invention there is provided a replaceable LED system with uniform glow on lighting comprising:

a bulb shaped moulding comprising plurality of LEDs and / or LED chip, with or without its operating circuitry permanently and securedly held within a shock, vibration resistant and unbreakable polymeric moulding / housing with atleast a part of externally visible portion of the lamp having a uniform glow region of light free of any visible external unidirectional glow of the LEDs .

In accordance with a preferred aspect of the present invention there is provided a replaceable LED system with uniform glow on lighting comprising:

a rectangular or square shaped moulding comprising plurality of LEDs and / or LED chip, with or without its operating circuitry permanently and securedly held within a shock, vibration resistant and unbreakable polymeric moulding / housing with atleast a part of externally visible portion of the lamp having a uniform glow of light free of any visible external unidirectional glow of the LEDs.

In accordance with yet another preferred aspect of the present invention there is provided a replaceable LED system with uniform glow on lighting comprising:

a cylindrical shaped moulding comprising plurality of LEDs and / or LED chip, with or without its operating circuitry permanently and securedly held within a shock, vibration resistant and unbreakable polymeric moulding / housing with atleast a part of the externally visible portion of the lamp having a uniform glow of fight free of any visible external unidirectional glow of the LEDs.

Importantly, the replaceable LEDs with uniformly externally viewable glow property of the invention can be used in any conventional holders and would not require any specialized installation for its use. In case of any requirement of replacement of the LED system the same can be simple taken out of the holder and a fresh one can be inserted in its place.

As is well known the operative components of the replaceable LED unit of the present invention include basic components such as the conventional LEDs and / or LED chips or any semiconductor light emitting device, the resistors, the diodes and capacitors which together are housed within the mouldings obtained of said polymeric materials.

In another aspect of present invention there is provided a process for manufacture of the replaceable of LED system with uniform glow characteristics comprising: -

CO providing moulding / housing of desired shape and configuration for moulding of the LED unit containing said LEDs and / or LED chip or any semiconductor light emitting device and with or without operating circuitry and defining a rear and a front portion;

(ii) providing atleast one LED lamp and / or LED chip and with or without its operative circuitry and moulding using selective polymeric materials to obtain a shock, vibration resistant and unbreakable unit with atleast a selective portion of the externally visible glowable portion of the system at the front having a uniform glow region of lighting free of any visible external unidirectional glow of LEDs / LED chip, the polymeric base being adapted to match desired shape and configuration for fitting to a holder and operative connection thereto.

In accordance with yet another aspect the method of manufacture of the replaceable LED system with uniform multidirectional external glow on lighting comprises: -

providing atleast one LED and/or LED chip, with or without its operating circuitry moulded to provide a permanent and secured shock and vibration resistant operative connection, said moulding carried out using selective polymeric materials such that only a selective portion of the externally visible portion of the lamp appear to have a uniform glow region of lighting free of any external unidirectional glow of the LED to provide a combination of said uniform glow regions and visible unidirectional LED glowing regions on the external visible portion.

In accordance with this method the decorative and aesthetic aspect of the LED system can be further improved upon by way of selectively providing uniformly glowing regions and some regions providing the unidirectional LED glow viewable.

In accordance with another aspect of the present invention there is provided a method for the manufacture of a replaceable LED system with uniform glow on lighting comprising:

providing any geometric or other shaped moulding comprising plurality of LEDs and / or LED chip ,wϊth or without its operating circuitry housed in a moulding using said selective polymeric material to provide a permanent and secured shock and vibration resistant operative connection, said moulding carried out such that the externally visible portion of the lamp provides for a uniform glow of light free of any visible external unidirectional glow of the LEDs.

In accordance with another aspect of the present invention there is provided a method for the manufacture of a replaceable LED system with uniform glow on lighting comprising:

providing a bulb shaped moulding comprising plurality of LEDs and/or LED chip with or without its operating circuitry housed in moulding done using said selective polymeric material to provide a permanent and secured shock and vibration resistant operative connection, said moulding carried out such that externally visible portion of the lamp appears a uniform glow of light free of any visible external unidirectional glow of the LEDs. In accordance with a preferred aspect of the method of manufacture of the replaceable LED system with uniform glow on lighting comprising:

providing a rectangular or square shaped moulding comprising plurality of LfDs and / or LED chip with or without its operating circuitry housed by a moulding carried out using said selective moulding materials to provide a permanent and secured shock and vibration resistant operative connection, said moulding carried out such that the externally visible portion of the lamp appears a uniform glow of light free of any visible external unidirectional glow of the LEDs.

In accordance with yet another preferred aspect of the present invention there is provided a method for the manufacture of a replaceable LED system with uniform glow on lighting comprising:

providing a cylindrical shaped moulding comprising plurality of LEDs and/or LED chip, with or without its operating circuitry housed in a moulding carried out using said selective moulding material to provide a permanent and secured shock and vibration resistant operative connection, said moulding carried out such that externally the lamp appears a uniform glow of light free of any visible external unidirectional glow of the LEDs .

In accordance with a preferred aspect the method of manufacture of the seamless replaceable LED system with uniform multidirectional external glow on lighting comprises: -

providing a glass mould ;

providing atleast one LED and / or LED chip or any semiconductor light emitting device, with or without its operating circuitry moulding in said glass mould to provide a permanent and secured shock , vibration resistant and unbreakable operative connection, said moulding carried out such that the external surface is seamless and atleast a selective portion of the externally visible portion of the lamp appear to have a / uniform glow on lighting free of any external unidirectional glow of the LED to provide a combination of said uniform glow regions and visible unidirectional LED glowing regions on the external visible portion . In accordance with a another preferred aspect the method of manufacture of the seamless replaceable LED system with uniform multidirectional external glow on lighting comprises: -

providing a glass mould ;

providing atleast one LED and/or LED chip or any semiconductor light emitting device, with or without its operating circuitry moulding in said glass mould to provide a permanent and secured shock, vibration resistant and unbreakable operative connection, said moulding carried out such that the externally visible portion of the lamp is seamless and appear to have a uniform glow on lighting free of any external unidirectional glow of the LED.

The above process of glass moulding specifically facilitates obtaining seamless surface finish of the replaceable LED systems of the invention.

The base of the unit is moulded to match to any conventional holder means to facilitate the replaceable characteristics of the unit of the invention.

The period of setting of the polymeric material in the above process will depend upon polymeric material also process of moulding whether following thermosetting and thermoplastic polymers.

BRIEF DESCRIPTION OF THE FIGURES

The details of the invention its objects and advantages are explained here under in greater detail in relation to non - limiting exemplary illustrations of the replaceable LED lamp with uniform glow characteristics with reference to the accompany figures wherein:

Figure 1: illustrates variety of a LED unit; disclosed in applicants co pending Indian Application no. 152/CAL/99

Figures 2 & 3: also illustrates varieties of filter screens and surface patterns thereon provided to try to avoid the unidirectional glow of LEOs as per the applicants co pending Indian Application no. 152/CAL/99;

Figures 4 & 5: illustrates known arrangements of plurality of LEDs in LED units to achieve multi directional glow;

Figure 6: illustrates as embodiment of the replaceable LED with uniform glow characteristics in accordance with the present invention;

Figures 7A to 7D: illustrate the LED system with the uniform glow of Fig 6 in various cross-sections which reveal the moulded housing of the LEDs and its operating circuitry in accordance with the present invention;

Figure 8: shows a conventional LED based backlight in cars and automobiles.

Figure 9: illustrates the LED system of the invention with uniform glow properties suitable for use as a backlight in cars / vehicles;

Figure 10 : illustrates in section the LED system with uniform glow properties suitable for use as a backlight in cars / vehicles of Figure 9 ;

Figures HA to HF: illustrates the external uniformly glow able portions of further varieties of LED system with uniform glow properties in accordance with the present invention.

Reference is first invited to Figure 1 which shows a replaceable LED unit in accordance with our earlier co-pending application. As shown in the figure in such replaceable variety the operating circuit and the LEDs (LD) are supported by way of a moulded base (BS). The rear of the unit is moulded and provided with metallic cap such as to provide a releasable operative connection with respect to a holder providing power source. In such LED units the LEDs are usually visible from the outside while glowing and the illumination from the unit is based on the unidirectional glow generated by the respective LEDs. Thus due to such unidirectional glow since the LEDs are disposed facing the front the illumination Is appreciated only from the front of the unit and even if the sides of the unit are transparent still due to the unidirectional glow of the LEDs the glow is not appreciated from the sides. Moreover, even at the front the illumination is along the straight path flowing from the LEDs and cannot provide any uniform glow in multiple directions.

As shown in Figures 2 and 3, in order to avoid the problems of unidirectional glow from the LEDs in such units attempts have been made to diffuse the unidirectional glow effect generated by the LEDs by using decorative filters (DF) with chequered or concentric surface patterns. However, use of such filters were found not sufficient to avoid the problems of unidirectional light emission from LEDs especially where an uniform glow in multidirection is desired.

Reference is now invited to Figures 4 & 5 which illustrated further known varieties of LED systems wherein in order to achieve all round visual effect the multiple LEDs (LD) are disposed not oniy at the front but in all other directions where the light is desired to be visible. In such modified forms while it is possible to have an illumination in multiple direction at the expense of added LEDs, however, the illumination achieved still inherited the limitation of the unidirectional glow of LEDs. Thus the visual effects in such modified forms also continued to be that of multiple unidirectional lights emanating from the several LEDs without any uniform glow characteristics.

Reference is now invited to Figure 6 which illustrates an embodiment of the LED system with uniform glow characteristics in accordance with the present invention. As would be apparent from Figure 6, unlike the system of Figure 4 the LEDs inside the bulb are not visible in the outer appearance and hence when glowing the unidirectional light effect from the LEDs are transformed to a uniform glow which can be apparent/visible from all directions.

The manner of achieving such LED system with uniform glow characteristics by way of the present invention is explained hereunder in greater detail in relation to accompany figures 7A to 7D. As clearly illustrated in said figures, in accordance with this LED system of the invention the LED along with the operating circuit are moulded together and housed in said polymeric moulding. The shaded portion in the figures show the polymeric moulded region (PM) with the LEDs (LD) and the operating circuitry (OP) permanently secured inside. At the rear the moulded portion is adapted to fit into a conventional holder and for the purpose a metal cap (MC) is provided for effective operative connection when installed with respect to the holder.

Figure 7D is a sectional view along AA' of Figure 7C showing the disposition of the LEDs in the moulded housing.

The polymeric material used is selectively provided such as to effectively take care of blocking the unidirectional glow from the LEDs and favour a more uniform external glow in multiple directions as may be desired. Importantly, the moulding of the unit is attended preferably involving agents to take care of avoiding the visual effects of unidirectional light emission from the LEDs and maintaining an uniform glow from outside in multiple directions.

It would be clearly apparent from the above that the LED system of the invention apart from maintaining the durability and non breakable characteristics essentially also takes care of cost-effectively transforming the unidirectional glow of LED in to a more uniform external glow by way of very simple process.

Reference is now invited to Figure 8 which illustrated a conventional LED based tail lamp use in automobile as brake light and the like. As is well known such LED systems essentially involve base unit (BA) adapted to support plurality of LEDs (LD) facing the top -The operating circuitry is housed in the base (BA). The top of the unit is covered by coloured usually red transparent polymeric cover (PC). As would be apparent from the figure is such conventional LED based tail lamp units the visual effect of glowing is that of a conventional unidirectional glow of LED. Therefore only from the front the glow of LEDs is properly appreciated while the glowing of the unit when viewed from the side is not that prominent. It therefore clearly affects the purpose of the indicator system on vehicles which should preferably show the glow uniformly in all visible directions uniformly.

Also in such conventional units since the top cover (PC) is usually obtained of plastic material, very often it is experience that such light units break even on minor impact which is very frequent in case of its use as tail/brake lamp in vehicles. Therefore as and when the cover brakes or is damaged there is need for its immediate replacement. Moreover this conventional unit is not shock and vibration resistant.

It is thus clearly apparent that LED based tail lamps presently in use have serious problems in terms of limitations of unidirectional glow of LED and also are subject to almost regular replacement / maintenance and it is also inflammable.

Reference is now invited to Figure 9 which shows an embodiment of a tail/brake lamp comprising the LED system with uniform externally visible glow in multiple directions grazing angle in accordance with the present invention. As shown in said figure by shade the polymeric moulded housing (MH) doesn't show the LEDs inside. Selected polymeric moulding is provided to achieve such purpose and provide for a more uniform glow effect of the LEDs free of any visual effects of its unidirectional glow properties. This takes care of on one hand of blocking the unidirectional glow of LED and provide for uniform external glow from all direction and on the other hand due to its solid protected moulding is directed to avoid problems of brakeage / damages in case of accidental impact / mishandling.

Fig 10 illustrates in section the moulded housing (MH) of the LED (LD)and operating circuitry (OP) in the tail/brake lamp of Figure 9 . As is clearly illustrated all the LED (LD) and operating circuitry (OP) are together coverer in the molded housing (MH) thereby LEDs and the operative circuitry (OC) are permanently housed within the moulding to take care of the unwanted unidirection glow effect generated by LEDs and also avoid the problem of operation failure in environments of shock and vibration as well as attain the desired break free characteristics in case of impact or mishandling.

The polymeric material used is selectively selected such that the external uniform glow is achieved on lighting without the visible unidirectional light generated by the respective LEDs. Preferably, this is achieved by way of providing suitable turbidity imparting agents such as preferably petroleum product and/or by way of chemically frosting inside the selective and possible use of glass mould especially for seamless variants of the system of the invention proposed hereinbefore. Alternatively, the polymeric material can comprise milled filler powder preferably phosphor powder or any other suitable milled powder.

Like wise the embodiments as per Figures 6 and 9, various other varieties of LED system with uniform glow and other benefit characteristics as per the present invention can be obtained and some further exemplary illustrations of which are provided in Figures 11 A to HF.

It is thus possible by way of the present invention to provide for a replaceable LED system / lamps which would be adapted such that the externally visible portion of the lamp caters to the required uniform glow / lighting free of any externally visible unidirectional glow of respective LEDs. The replaceable LED system of the invention is one hand cost effective and on the other hand simple to manufacture thereby making such uniformly glow able LED units available at cost effective prices for a wide range of end use / applications. The system is also vibration / shock resistant and avoids problems of fragility and consequential breakage due to mishandling and / or accidental impacts. The replaceable LED unit with uniform glow property would have long life and durable use even in environments of shock and vibration and it is also fire retardant. The system is simple to manufacture without the need for any expensive/ heavy machinery and/or skilled expertise and importantly favours obtaining of replaceable LEDs with seamless external surface of variety of shape and configuration for varied application uses as domestic, decorative and/or industrial applications.