Patent Description:
The power tool may be operated electrically or pneumatically. To this end, the motor is an electric motor or a pneumatic motor. The electric power tool may be supplied with electric energy by a detachable battery located at least partially inside or otherwise attached to the tool housing or by means of a cable connection to a mains power supply. One or more gear members may be located functionally between the motor and the working element. The one or more gear members are located inside the tool housing. The one or more gear members may comprise but are not limited to at least one of a bevel gear arrangement, a coaxial reduction gear arrangement, and an epicyclic or planetary gear arrangement. The hand-held power tool may be but is not limited to at least one of a rotary drill, a hammer drill, a cordless screwdriver, a polishing machine, a sanding machine, and a grinding machine.

The working element of a drill or cordless screwdriver is preferably a drill chuck to which a drill bit, screwdriver bit or the like may be releasably attached, for instance by means of a clamping mechanism or a coupling mechanism. The drill chuck performs a purely rotational working movement. Additionally, in the case of a drill hammer, a linear back-and-forth movement in the direction of a longitudinal extension of a drill bit attached to the drill chuck, may the drill chuck may superimpose the rotational movement.

The working element of a polishing or sanding machine is preferably embodied as a backing pad. A polishing member (e.g. a foam pad, wool pad, micro-fibre pad, or the like) or sanding member (e.g. a sanding paper, sanding fabric, abrasive pad, or the like) may be releasably attached to a bottom surface of the backing pad, for instance by means of hook-and-loop fastening members. The backing pad of a polishing machine may perform a purely rotational, a random-orbital or a gear-driven working movement. The backing pad of a sanding machine may perform a random-orbital or an eccentric working movement.

The working element of a grinding machine is preferably embodied as a coupling member to which a grinding disc can be releasably attached, for instance by means of a coupling mechanism or a screw-nut connection. The coupling member performs a purely rotational working movement.

It is well-known in the prior art to provide one or more LEDs at the front of a tool housing of a hand-held power tool, the LEDs emitting white light focussed on a working area during intended use of the power tool. The idea is to illuminate the working area in order to allow the user to use the power tool also in spaces and on working surfaces of work pieces which are only poorly illuminated with room light or sun light (e.g. <CIT> and <CIT>).

Furthermore, it is well-known in the prior art to provide one or more LEDs in a tool housing of a hand-held power tool, the LEDs serving as control lights and emitting light, possibly in different colours, depending on a current operation status (e.g. a current charge state of a battery) of the power tool (e.g. <CIT>). For instance, an LED may be provided in the tool housing, which emits red light if the charge state of a battery of the power tool falls below <NUM>%. The LED(s) provided as control lights in the tool housings of known power tools merely provide a small light spot with very restricted dimensions. Due to its small dimensions, the control lights are often not clearly and immediately visible to the user of the power tool. Even if a plurality of LEDs is provided in the tool housing and even if they are designed to emit light of different colours, the overall appearance of such control lights is not very appealing to the user of the power tool. The design aspects are completely neglected with LED control lights in known power tools. The main focus is directed towards functional as well as technical aspects and to a realization of the control lights as cheap as possible.

<CIT> discloses a hand-held power tool in the form of a driving tool for ejecting a fastener (a U-shaped staple needle). An elongated light guide is externally attached to a tool housing and emits light along its longitudinal extension in a direction that is essentially perpendicular to the longitudinal extension. The light guide has a cross section with an engaging portion integrally formed with the light guide. The engaging portion interacts with a respective holding portion of the tool housing in order to directly attach the light guide, in particular to have the engaging portion clamped between two housing shells of the tool housing. However, the engaging portion making an integral part of the light guide may have a negative impact on the light propagation within the light guide and on the decoupling of light from the light guide. Thus, the efficiency of the light guide is not very good. Further, the light guide of the known power tool is exposed to mechanical, chemical and/or meteorological influences which might damage the light guide.

It is, therefore, an object of the present invention to provide a hand-held power tool which combines the effort of optical communication of the current operation status of the power tool with new and innovative design aspects, and in which an elongated light emitting device can be easily mounted to the tool housing. In particular, it is an object of the invention to provide fora fast and easy mounting of the elongated light emitting device preferably in a detachable manner. Furthermore, it is a further object to provide for a safe and reliable protection of the elongated light emitting device attached to the tool housing.

In order to solve this object, a hand-held power tool comprising the features of claim <NUM> is suggested. In particular, a power tool according to the preamble of claim <NUM> is suggested, which further comprises at least one elongated holding arrangement made of a transparent material and adapted for receiving and surrounding at least part of the elongated light emitting device and for being attached to the tool housing.

The invention suggests to provide one or more elongated light emitting devices on an external surface of the tool-housing, the light emitting devices emitting light along at least part of their longitudinal extensions, and, therefore, providing for a much larger illuminated surface. In particular, the illuminated surface may extend over more than half the length of the tool housing and/or around more than half the external circumference of the tool housing. Due to the longitudinal extension of the at least one light emitting device, a user of the power tool has almost no chance to cover the entire illuminated surface with his hands when holding the power tool during its intended use. Independent from how the user is holding the power tool, he will always be able to see at least part of the light emitted by the elongated light emitting device. Besides, the at least one elongated light emitting device located on the external surface of the tool housing with the resulting elongated illuminated surface and its longitudinal extension, gives the manufacturer of power tools the chance to introduce a completely new and innovative design of his power tools. This may be the case, for instance, if the longitudinal extension of the at least one elongated light emitting device follows a major design line of the tool housing. Furthermore, a corporate identity can be realized by a certain type of light emitting device (e.g. location on the tool housing, form, extension of the light emitting device, light colour emitted by the light emitting device, etc.) with which all power tools of a certain manufacturer are equally provided.

The at least one elongated light emitting device is not directly attached to the tool housing but rather indirectly by means of the at least one elongated holding arrangement, which in turn is attached to the tool housing. By means of the elongated holding arrangement, the elongated light emitting device can be easily and securely attached to the tool housing. The elongated light emitting device can be easily located inside an internal space of the elongated holding arrangement, when it is separate from the tool housing, and then the assembly of the two components (light emitting device and holding arrangement) can be attached to the tool housing. Due to the transparency of the elongated holding arrangement, light emitted by the elongated light emitting device simply transmitted through the elongated holding arrangement, essentially without any losses. Additionally, the elongated holding arrangement may provide for a protection of the elongated light emitting device received therein.

According to a preferred embodiment of the invention, it is suggested that the at least one elongated holding arrangement has an O-shaped or U-shaped cross section, wherein the at least one elongated light emitting device is received inside an internal space of the O-shape or U-shape. In the case of a U-shaped cross section of the elongated holding arrangement it can be attached to the tool housing such that the opening between the two approximately parallel legs of the U-shape faces towards the tool housing, so that the internal space of the elongated holding arrangement is closed by the U-shape of the elongated holding arrangement in cooperation with the outside of the tool housing. This results in an overall protection of the elongated light emitting device to all sides.

Advantageously, the tool housing comprises at least two housing shells, which are attached to each other along a butt joint during tool housing assembly in order to form the tool housing, and the at least one elongated holding arrangement has at least two attachment elements adapted for being clamped between two housing shells during the tool housing assembly. The attachment elements are preferably spaced apart from each other along the longitudinal extension of the elongated holding arrangement.

Clamping the elongated holding arrangement between two housing shells has the advantage that by disassembling the tool housing and separating the two housing shells from each other, the elongated holding arrangement can be easily separated from the tool housing, e.g. for replacing the elongated light emitting device. Furthermore, the clamping step can be easily integrated into a conventional tool housing assembly process. No additional attachment steps e.g. for gluing the elongated holding arrangement to the tool housing or the like, have to be added to the tool housing assembly process. The housing shells may be attached to each other by means of glue, screws, snap-in connections or the like.

Usually the butt joint between two housing shells forms a groove in which the elongated holding arrangement, clamped between the two housing shells, can be located. This has the advantage that the elongated holding arrangement does not protrude by much beyond the external surface of the tool housing bordering the groove, thereby protecting the assembly of the two components from damage. Furthermore, the butt joint usually reflects a major design line of the tool housing. Locating the at least one elongated light emitting device along the butt joint further emphasizes the major design line, when the light emitting device emits light.

It is suggested that the at least one elongated holding arrangement is made of a transparent plastic material, in particular PC or PMMA. Plastic material is particularly adapted for use with the elongated holding arrangement due to its high durability, good resistance to external influences and to breakage, its light weight, and its simple, fast and inexpensive production.

It is further suggested that the at least one elongated holding arrangement is made of a rigid material which before attachment to the tool housing has a rigid three dimensional form corresponding to the three dimensional form of a part of the tool housing to which the at least one elongated holding arrangement is to be attached. This facilitates the assembly of the elongated holding arrangement considerably.

The elongated holding arrangement can be made of a coloured material, in order to give the light emitted by the elongated light emitting device a desired colour. Preferably, the at least one elongated holding arrangement is made of a material and has internal and/or external light transmission surfaces which impose no light scattering effect on the light emitted by the at least one elongated light emitting device and passing through the at least one elongated holding arrangement. In particular, the material of the elongated holding arrangement has not light scattering particles therein. Further, the internal and/or external light transmission surfaces of the elongated holding arrangement have no light scattering structure, for example a matted or frosted surface. Scattering of light is considered to be an uncontrollable light diffusion. It is however possible, that the internal and/or external light transmission surfaces of the elongated holding arrangement have light directing elements (e.g. prisms or cylinder lenses or sections thereof) which direct the light passing through the at least one elongated holding arrangement in a controllable manner towards a desired direction.

According to a preferred embodiment of the present invention, it is suggested that the at least one elongated light emitting device comprises one of.

An electroluminescent (or EL) wire comprises a thin copper wire coated by an electroluminescent material (e.g. phosphor or the like) that produces light through electroluminescence when an alternating current at relatively high frequencies is applied to it. An EL wire produces a <NUM>° homogeneous unbroken line of visible light in a certain colour. A protecting sheathing around the electroluminescent material which is preferably made of a plastic or rubber material can influence the wavelength of the light emitted by the EL wire. Thus, the colour of the light emitted by the EL wire can be set by using a sheathing made of a certain plastic material or containing certain particles. The EL wire has a respectively thin diameter which makes it highly flexible.

The EL wire simply has to be electrically connected to a respective driver stage of a control unit of the power tool located in the tool housing. To this end, one or more holes can be provided in the tool housing through which the EL wire is led into the housing (and electrically connected inside the housing) or through which one or more electric cables are led out of the housing to the EL wire (and electrically connected outside the housing).

Preferably, at least on part of one side of the EL wire facing the tool housing a reflective surface is provided. The reflective surface may be in the form of a coating or a foil made of a reflective material, e.g. metal. The reflective surface may be applied onto an outer boundary surface of the EL wire and/or onto a part of the external surface of the tool housing adjacent to the EL wire and/or onto a part of the elongated holding arrangement. The reflective surface directs light which is emitted toward the tool housing in the opposite direction away from the tool housing. This significantly increases the efficiency of the EL wire.

The use of an optical light guide has the advantage that the light source may be located distant from the illuminated surface at the outside of the tool housing. In particular, the light source can be located inside the tool housing where it is protected from dust, humidity, etc. Furthermore, an electric connection to a battery or a power supply unit can be achieved more easily if the light source is located inside the tool housing near the battery or the power supply unit.

The light source is preferably located inside the tool housing. One or more holes can be provided in the tool housing and/or in the elongated holding arrangement, through which the light source may emit light towards the optical light guide located outside of the tool housing. Alternatively, one or both opposing ends of the optical light guide may be led through the hole into the inside of the tool housing near the light source. Preferably, the light source couples light into the light guide at one or both opposing end surfaces of the light guide. One or more light sources may couple light into one end surface of the optical light guide.

Preferably, the light coupled into the optical light guide is transmitted within the light guide along the longitudinal extension of the light guide by means of total internal reflection (TIR) at external boundary surfaces of the optical light guide. In general, TIR takes place at the boundary between two transparent media when a ray of light in a medium of higher index of refraction (i.e. the optical light guide) approaches another medium (i.e. the surrounding air) at an angle of incidence greater than the critical angle. The critical angle depends on the material of the optical light guide and on the wavelength (i.e. colour) of the light.

Alternatively or additionally, it is suggested, that the optical light guide is made of a glass material, a transparent plastic material, in particular of an acrylic material like polymethylmethacrylate (PMMA) or of polycarbonate (PC), or a transparent rubber material. These materials have a good optical clarity, good mechanical properties, and very little natural scintillation response to ionizing radiation. Impurities in the rubber material may be used for intentionally coupling out the light transmitted through the light guide by means of TIR in the direction essentially perpendicular to the longitudinal extension of the elongated light emitting device.

The optical light guide may comprise decoupling elements located along at least part of the longitudinal extension of the optical light guide, wherein the decoupling elements are designed to couple out at least part of the coupled-in light in a direction that is essentially perpendicular to the longitudinal extension of the optical light guide. The decoupling elements act as virtual light sources through which the light is coupled out of the optical light guide in the direction essentially perpendicular to the longitudinal extension of the light guide.

The decoupling elements can comprise prisms, inside the optical light guide or on an outer boundary surface of the light guide. A roughening (matting or frosting) on light reflecting surfaces of the decoupling elements and/or on the outer boundary surfaces of the light guide through which the light is coupled out of the light guide can provide for an additional scattering and homogenisation of the out-coupled light.

Advantageously, the decoupling elements are designed and located at or in the optical light guide in such a manner as to couple out the at least part of the coupled-in light into a <NUM>°-space to one side of the optical light guide, preferably towards the environment surrounding the tool housing. This embodiment can significantly enhance the efficiency of the elongated light emitting device. Almost all the light coupled into the light guides is coupled out of the light guide in a direction in which it can be seen by an observer. Almost no light is coupled out of the light guides towards the tool housing, where it would not be seen by an observer.

In order to further enhance the efficiency of the elongated light emitting device, it is suggested that a bundling optic is arranged between the light source and a light input end surface of the optical light guide, into which the light source couples at least part of its emitted light, wherein the bundling optic is designed to bundle at least part of the light emitted by the light source and to couple a larger proportion of the emitted light into the optical light guide than if the bundling optic was not present. Conventional light sources emit light in a rather large three-dimensional space. For example, an incandescent lamp emits light into almost the entire <NUM>°-space surrounding the lamp and an LED emits light into a <NUM>°-space adjacent to a light emitting surface of the LED. The bundling optic focuses as much light as possible emitted by the light source onto the input surface of the optical light guide. The bundling optic can make an integral part of the light source and/or of the optical light guide.

Preferably, the at least one light source is embodied as a semiconductor light source, in particular as a light emitting diode (LED). Such light sources are small and consume very little electricity. They are available in a variety of versions, including different power ranges (brightness) and colours of the emitted light. Such light sources can be easily integrated into existing electronic components inside the tool housing.

The elongated light emitting device may have almost any cross sectional form, including but not limited to: square, rectangular, and polygonal. However, according to a preferred embodiment of the present invention, the electroluminescent wire or the optical light guide has a round or oval cross section. Such electroluminescent wires emit light particularly homogenously. Such optical light guides propagate the in-coupled light by means of TIR particularly efficiently. No so-called hot spots (areas in which light rays accumulate and thus provide a particularly high brightness) are formed in such electroluminescent wires or optical light guides.

According to yet another preferred embodiment of the present invention, it is suggested that the elongated light emitting device comprises an elongate diffusing lens with a longitudinal extension. The diffusing lens may have a round, oval, square, rectangular or polygonal cross section. Preferably, the diffusing lens has a cross sectional form of a segment of such a cross section, in particular of a semicircle. The diffusing lens may be made of glass, a transparent plastic material or a rubber material. The diffusing lens may have any colour in order to give the emitted light a desired colour. The diffusing lens is preferably made of a solid material. It may have a diffusing structure, e.g. a micro structure on one or more of its external surfaces through which the light is transmitted. A plurality of discrete light sources, preferably in the form of LEDs, are arranged spaced apart from each other along the longitudinal extension of the diffusing lens so that they emit light substantially transversely to the longitudinal extension of the diffusing lens therethrough. When passing through the diffusing lens, the light emitted by the LEDs is scattered to such an extent that the light emitting side of the diffusing lens, which preferably extends opposite the light sources over at least part of the longitudinal extension of the diffusing lens, is uniformly illuminated. On the light emitting side, the discrete light sources that emit light through the diffusing lens are no longer recognisable as such. Instead, the light emitting side of the diffusing lens emits a homogeneous light distribution.

According to a preferred embodiment, the light sources associated to the light guide or to the diffusing lens are designed to emit light of at least two different colours. The light sources may, for instance, be embodied as RGB-LEDs. Similarly, the power tool may comprise at least two electroluminescent wires or light sources which emit light of different colours. Preferably, the colour of the light emitted by the electroluminescent wires or the light sources depends on a current operation status of the hand-held power tool, comprising but not limited to one or more of:.

According to another a preferred embodiment, the electroluminescent wire or the light source is designed to emit light continuously or intermittently at a certain frequency. Preferably, whether the electroluminescent wire or the light source emits light continuously or intermittently and/or the frequency of the intermittently emitted light depends on a current operation status of the hand-held power tool, comprising but not limited to one or more of:.

The inventor has in particular contemplated the following ways of indicating an operating status of the power tool to a user:.

Further features and advantages of the present invention may become more apparent from the following description referring to the figures showing preferred embodiments of the invention. The figures show:.

<FIG> shows an example of a hand-held electric power tool <NUM> according to the present invention in a perspective view. <FIG> shows a schematic longitudinal section through the power tool <NUM> of <FIG>. The power tool <NUM> is embodied as a random orbital polishing machine (or polisher). The polisher <NUM> has a tool housing <NUM>, essentially made of a plastic material. The tool housing <NUM> comprises a handle <NUM> at its rear end and a grip element <NUM> at its front end. A user of the power tool <NUM> may hold the power tool <NUM> with one hand at the handle <NUM> and with the other hand apply a certain amount of pressure on the grip element <NUM> during the intended use of the power tool <NUM>.

An electric power supply line <NUM> with an electric plug at its distal end exits the tool housing <NUM> at the rear end of the handle <NUM>. At the bottom side of the handle <NUM>, a switch <NUM> is provided for activating and deactivating the power tool <NUM>, i.e. selectively turning it on and off. The switch <NUM> can be continuously held in its activated position by means of a push button <NUM>. The power tool <NUM> can be provided with adjustment means <NUM>, for example in the form of a knurled wheel, for setting the rotational speed of the tool's electric motor <NUM> (see <FIG>) to a desired value. The tool housing <NUM> can be provided with cooling or venting openings <NUM> for allowing heat from electronic components and/or the electric motor <NUM> both located inside the tool housing <NUM> to dissipate into the environment and/or for allowing cooling air from the environment to enter into the tool housing <NUM>.

As can be seen from <FIG>, the power tool <NUM> has an electric motor <NUM>. The electric motor <NUM> is preferably of the brushless type. Instead of the connection of the power tool <NUM> to a mains power supply by means of the electric cable <NUM>, the power tool <NUM> could additionally or alternatively be equipped with a rechargeable or exchangeable battery (not shown) located at least partially inside the tool housing <NUM>. In that case the electric energy for driving the electric motor <NUM> and for operating the other electronic components of the power tool <NUM> would be provided by the battery. If, despite the presence of a battery, the electric cable <NUM> was still present, the battery could be charged with an electric current from the mains power supply before, during or after operation of the power tool <NUM>. The presence of a battery would allow the use of an electric motor <NUM> which is not operated at the mains power supply voltage (230V in Europe or 110V in the US and other countries), but rather at a reduced voltage of, for example, 12V, 24V, 36V or 42V depending on the voltage provided by the battery.

The power tool <NUM> has a working element in the form of a plate-like backing pad <NUM> rotatable about a first rotational axis <NUM>. In particular, the backing pad <NUM> of the tool <NUM> shown in <FIG> performs a random orbital movement <NUM>. With the random orbital movement <NUM> the backing pad <NUM> performs a first rotational movement about the first rotational axis <NUM>. Spaced apart from the first rotational axis <NUM>, a second rotational axis <NUM> (see <FIG>) is defined, about which the backing pad <NUM> is freely rotatable independently from the rotation of the backing pad <NUM> about the first rotational axis <NUM>. The second axis <NUM> runs through the balance point of the backing pad <NUM> and parallel to the first rotational axis <NUM>. The random orbital movement <NUM> is realized by means of an eccentric element <NUM> which is directly or indirectly driven by the motor <NUM> and which performs a rotation about the first rotational axis <NUM>. A fulcrum pin <NUM> is held in the eccentric element <NUM> and guided freely rotatable in respect to the eccentric element <NUM> about the second rotational axis <NUM>. An attachment member <NUM> (e.g. an enlarged head portion) of the fulcrum pin <NUM> is inserted into a recess <NUM> provided in a top surface of the backing pad <NUM> and attached thereto in a releasable manner, e.g. by means of a screw (not shown) or by means of magnetic force. The eccentric element <NUM> may be directly attached to a driving shaft <NUM> of the power tool <NUM> in a torque proof manner.

One or more gear members may be located functionally between the motor <NUM> and the driving shaft <NUM> of the power tool <NUM>. In the embodiment shown in <FIG>, a gear member in the form of a bevel gear arrangement <NUM> is provided between the motor <NUM> and the driving shaft <NUM>. The bevel gear arrangement <NUM> comprises two meshing bevel gears, one fixedly attached to a motor shaft <NUM> of the motor <NUM> and the other fixedly attached to the driving shaft <NUM>. The bevel gear arrangement <NUM> transmits rotary movements and torques from the motor shaft <NUM> rotatable about a first rotational axis <NUM> to the driving shaft <NUM> rotatable about the first rotational axis <NUM>.

The two axes <NUM> and <NUM> may intersect each other at an angle α, preferably between <NUM>° and <NUM>°, more preferably between <NUM>° and <NUM>°, most preferably of <NUM>° or <NUM>°. The bevel gear arrangement <NUM> may have a transmission ration of <NUM> or of #<NUM>, in particular of ><NUM>. Instead of the mechanical bevel gear arrangement <NUM>, it would also be possible to implement a magnetic bevel gear arrangement having non-meshing magnetic gear wheels which transmit rotary movements and torques through magnetic force. Additionally or alternatively, further gear members, e.g. a coaxial gear arrangement or an epicyclic or planetary gear arrangement, may be located between the motor shaft <NUM> and the driving shaft <NUM>. The alternative or additional gear members may work mechanically through meshing gear wheels or magnetically through magnetic force. Finally, it would also be possible that the motor <NUM> directly drives the driving shaft <NUM> without any gear members functionally located between the motor <NUM> and the driving shaft <NUM>, wherein the driving shaft <NUM> would be formed by the motor shaft <NUM> itself.

The backing pad <NUM> is made of a rigid material, preferably a plastic material, which on the one hand is rigid enough to carry and support a polishing member <NUM> for performing the desired work on the working surface of the work piece (e.g. polishing the surface of a vehicle body, a boat or aircraft hull) during the intended use of the power tool <NUM> and to apply a force to the backing pad <NUM> and the polishing member <NUM> in a direction downwards and essentially parallel to the first rotational axis <NUM> and which on the other hand is flexible enough to avoid damage or scratching of the surface to be worked by the backing pad <NUM> or the polishing member <NUM>, respectively. The polishing member <NUM> may comprise a foam or sponge pad, a microfiber pad, and a real or synthetic lambs' wool pad. In <FIG> the polishing member <NUM> is embodied as a foam or sponge pad. The polishing member <NUM> is attached to a bottom surface of the backing pad <NUM> in a releasable manner, e.g. by means of a hook-and-loop fastener. In the case where the power tool <NUM> is a sander, a sanding member would be attached to the bottom surface of the backing pad <NUM>, the sanding member comprising a sanding pad, or a sheet-like sanding paper or fabric. The backing pad <NUM> and the polishing member <NUM> or the sanding member, respectively, preferably have a circular form.

Of course, the power tool <NUM> according to the present invention could also be embodied as another type of power tool, e.g. as a rotary drill, a hammer drill, a cordless screwdriver, a sanding machine, or a grinding machine, just to name a few. With other types of power tools <NUM>, the working element may be embodied differently, e.g. as a drill chuck or the like. Furthermore, the power tool <NUM> could be operated pneumatically by compressed air instead of electrically by electric energy. In that case the motor <NUM> would be embodied as a pneumatic motor. The electric energy for operating electronic components (e.g. a controller unit, a solenoid-driven pneumatic valve, an elongated light emitting device described below or the like) of the pneumatic power tool may be provided by a dynamo which is driven by the pneumatic motor or otherwise by compressed air and/or by a rechargeable battery, which may be charged by means of a motor-driven dynamo, an external charging device or the like.

As can be seen in <FIG>, it is suggested that the power tool <NUM> comprises at least one elongated light emitting device <NUM> having a longitudinal extension <NUM> and located at least partially on an external surface of the tool housing <NUM>. The at least one elongated light emitting device <NUM> is designed to emit light along at least part of its longitudinal extension <NUM> in a direction that is essentially perpendicular to the longitudinal extension <NUM> of the elongated light emitting device <NUM>. Preferably, the elongated light emitting device <NUM> emits light along its entire longitudinal extension <NUM>. <FIG> shows only a single elongated light emitting device <NUM> located on one side of the tool housing <NUM>. The opposite side of the tool housing <NUM> may be provided with another elongated light emitting device <NUM>. Of course, one or both sides of the tool housing <NUM> may each be provided with more than one elongated light emitting device <NUM>.

According to the embodiment of <FIG>, the tool housing <NUM> comprises two housing shells <NUM>, <NUM>, which are attached to each other along a butt joint <NUM> during a tool housing assembly in order to form the tool housing <NUM>. The at least one elongated light emitting device <NUM> extends along at least part of the butt joint <NUM>. In <FIG>, the elongated light emitting device <NUM> extends along the entire butt joint <NUM> between the two housing shells <NUM>, <NUM>. The housing shells <NUM>, <NUM> may be attached to each other by means of glue, screws, snap-in connections or the like, in order to form the tool housing <NUM>.

According to the invention, at least part of the elongated light emitting device <NUM> is received in and surrounded at least partially by at least one elongated holding arrangement <NUM> made of a transparent material (see <FIG>). The elongated holding arrangement <NUM> is adapted for being attached to the tool housing <NUM>. As can be seen in <FIG>, the elongated holding arrangement <NUM> has a U-shaped cross section. The at least one elongated light emitting device <NUM> is received inside an internal space <NUM> of the U-shape. An opening of the U-shaped elongated holding arrangement <NUM> is directed towards the tool housing <NUM> thereby closing off the internal space <NUM> from the outside. Thus, the elongated holding arrangement <NUM> provides for a good protection of the elongated light emitting device <NUM>.

Alternatively, the at least one elongated holding arrangement <NUM> has an O-shaped cross section and the at least one elongated light emitting device <NUM> is received inside the internal space <NUM> of the O-shape.

As can be seen from <FIG>, the at least one elongated holding arrangement <NUM> has at least two attachment elements <NUM> adapted for being clamped between the two housing shells <NUM>, <NUM> of the tool housing <NUM> during the tool housing assembly. Of course, multiple other ways of attaching the elongated holding arrangement <NUM> to the tool housing <NUM> are conceivable, too, e.g. by means of a snap-in connection, a press-fit connection or glue.

The at least one elongated holding arrangement <NUM> is preferably made of a transparent plastic material, in particular PC or PMMA. Of course, the elongated holding arrangement <NUM> could be made of other suitable materials, in particular plastic materials, too.

Preferably, the at least one elongated holding arrangement <NUM> is made of a rigid material which before attachment to the tool housing <NUM> (see <FIG>) has a three dimensional form corresponding to the three dimensional form of that part of the tool housing <NUM> to which the at least one elongated holding arrangement <NUM> is to be attached (see <FIG>).

It is further suggested that the at least one elongated holding arrangement <NUM> is made of a material and has internal and/or external light transmission surfaces <NUM>, <NUM> which impose no light scattering effect on the light emitted by the at least one elongated light emitting device <NUM> and passing through the at least one elongated holding arrangement <NUM>. The light emitted by the elongated light emitting device <NUM> is at most subject to refraction at the internal and/or external light transmission surfaces <NUM>, <NUM> when passing through the elongated holding arrangement <NUM>. However, due to the U- or O-shaped circumferential form of the elongated holding arrangement <NUM>, and the at least partial circular curvature of the elongated holding arrangement <NUM> surrounding the elongated light emitting device <NUM>, the light emitted radially outwards by the elongated light emitting device <NUM> passes through the elongated holding arrangement <NUM> even without any refraction.

Usually the butt joint <NUM> between the two housing shells <NUM>, <NUM> forms a groove in which the elongated holding arrangement <NUM> with the elongated light emitting device <NUM> received therein can be placed. This has the advantage that the elongated holding arrangement <NUM> does not protrude beyond the external surface of the tool housing <NUM> or protrudes only slightly, which protects it from mechanical stress, in particular impacts from outside. Furthermore, the butt joint <NUM> usually reflects a major design line of the tool housing <NUM>. Locating the at least one elongated light emitting device <NUM> (preferably by means of the elongated holding arrangement <NUM>) along or within the butt joint <NUM> further emphasizes the major design line, when the light emitting device <NUM> emits light.

The tool housing <NUM> may comprise at least one embossed character and/or at least one embossed symbol. The at least one elongated light emitting device <NUM> may be located (preferably by means of an elongated holding arrangement) in at least part of the embossed character and/or the embossed symbol thereby emphasizing the character or symbol when emitting light. The embossed character may comprise one or more letters or numbers. Additionally or alternatively, the embossed character may comprise the name of the power tool <NUM> (e.g. "BigFoot"). Further, it may reflect hints or instructions for use of the power tool <NUM>, e.g. "I/O" for indicating the positions of the on/off switch <NUM> or numbers from "<NUM>" to "<NUM>" or "<NUM>. max" for indicating different motor speeds. The embossed symbol may comprise a graphic symbol (e.g. a paw of the BigFoot-logo) relating to the manufacturer of the tool <NUM> or to the model of the tool <NUM>. By locating the elongated light emitting device <NUM> (preferably by means of an elongated holding arrangement) in at least part of the embossed character and/or the embossed symbol these can be emphasized for better perception by an observer. Additionally, the informational aspect of the light emitted by the elongated light emitting device <NUM> (i.e. information on the current operating status of the power tool <NUM>) can be combined with a design aspect emphasizing the character and/or symbol embossed into the tool housing <NUM>.

The tool housing <NUM> may further have one or more recesses, in which actuating or operating elements (e.g. switches, buttons or dials) are located in a manner movable in respect to the tool housing <NUM>. The actuating or operating elements could be, for instance, I/O-switch <NUM>, push button <NUM> or speed dial <NUM>. The recesses in the tool housing <NUM> and the actuating or operating elements <NUM>, <NUM>, <NUM> located in the recesses, leave gaps between the sides of the actuating or operating elements <NUM>, <NUM>, <NUM> and the edges of the tool housing <NUM> defining the recesses. The at least one elongated light emitting device <NUM> may be located (preferably by means of an elongated holding arrangement) in at least part of these gaps between the sides of the actuating or operating elements <NUM>, <NUM>, <NUM> and the edges of the tool housing <NUM> defining the recesses. This makes operation of the power tool <NUM> and actuation of the illuminated actuating or operating elements <NUM>, <NUM>, <NUM> in dimly lit environments easier.

The elongated light emitting device <NUM> can be designed in many different ways. It is suggested that the at least one elongated light emitting device <NUM> comprises one of.

The electroluminescent (or EL) wire <NUM> has a longitudinal extension <NUM> and is designed to emit light along at least part of its longitudinal extension in a direction <NUM> that runs essentially perpendicular to its longitudinal extension <NUM> upon activation of the EL wire <NUM>. An example for such an EL wire <NUM> is shown schematically in <FIG>. The EL wire <NUM> comprises a thin copper wire <NUM> coated by an electroluminescent material <NUM> (e.g. phosphor) that is surrounded by a very fine copper wire <NUM>. Around the copper wire <NUM> a clear protective sheathing or sleeve <NUM> and surrounding that a coloured sleeve <NUM> (e.g. made of plastic, for example PVC, or any other kind of soft rubber) may be provided. Instead of the separated coloured sleeve <NUM>, the protective sheathing <NUM> could be provided in a certain colour or with particles which alter the wavelength of the emitted light, in order to set the colour of the light emitted by the EL wire <NUM> to a desired value. In that case, no additional coloured sleeve <NUM> would be required.

When an alternating current <NUM> is applied to the electroluminescent material <NUM>, it produces light through electroluminescence. The alternating current electric potential and the frequency are relatively high. The alternating current electric potential may be up to <NUM> V, and the frequency may be up to <NUM>. The alternating current electric potential is preferably in the range of <NUM>-<NUM> V and the frequency is around <NUM>. Of course, the electric potential and/or the frequency may have any other desired value, too. The EL wire <NUM> produces a <NUM>° homogeneous unbroken line of visible light in a given colour. It has a relatively thin diameter (in the range of one or more millimetres or even thinner) which makes it highly flexible.

After attachment of the EL wire <NUM> to the tool housing <NUM> by means of at least on elongated holding arrangement <NUM>, the EL wire <NUM> simply has to be electrically connected to a respective driver stage of a control unit of the power tool <NUM> located in the tool housing <NUM>. To this end, one or more holes (not shown) can be provided in the tool housing <NUM> through which the EL wire <NUM> is led into the housing <NUM> and electrically connected inside the housing <NUM> or through which one or more electric cables (not shown) are led out of the housing <NUM> to the EL wire <NUM> and electrically connected outside the housing <NUM>.

In order to increase the efficiency of the EL wire <NUM>, it may be advantageous if at least part of one side of the EL wire <NUM> facing the tool housing <NUM> is assigned to a reflective surface (not shown). The reflective surface may be in the form of a coating or a foil made of a reflective material, e.g. metal. The reflective surface may be applied onto an outer boundary surface of the EL wire <NUM> and/or onto a part of the external surface of the tool housing <NUM> adjacent to the EL wire <NUM> and/or to a part of an internal surface <NUM> of the elongated holding arrangement <NUM>. The reflective surface directs light which is emitted towards the tool housing <NUM> in the opposite direction away from the tool housing <NUM> towards an observer.

The at least one optical light guide <NUM> has a longitudinal extension <NUM> and is assigned to at least one light source <NUM> designed to emit light upon its activation and to couple at least part of the emitted light <NUM> into the optical light guide <NUM>. The light source <NUM> preferably comprises one or more light emitting devices (LEDs). The optical light guide <NUM> is designed to couple out at least part of the coupled-in light <NUM> along at least part of its longitudinal extension <NUM> in a direction <NUM> that is essentially perpendicular to its longitudinal extension <NUM>.

The use of an optical light guide <NUM> has the advantage that the light source <NUM> may be located distant from the illuminated surface of the light guide <NUM>, which is located at the outside of the tool housing <NUM>. In particular, the light source <NUM> can be located inside the tool housing <NUM> where it is protected from dust, humidity, etc. Furthermore, an electric connection of the light source <NUM> to a battery or a power supply unit can be achieved more easily if the light source <NUM> is located inside the tool housing <NUM>, preferably near the battery or the power supply unit.

In the embodiment of <FIG>, the light source <NUM> is located inside the tool housing <NUM>. One or more holes <NUM> can be provided in the tool housing <NUM> through which the light source <NUM> may emit light towards the optical light guide <NUM> located outside of the tool housing <NUM>. Alternatively, one or both opposing ends of the optical light guide <NUM> may be led through the holes <NUM> into the inside of the tool housing <NUM> near the light source <NUM>. Preferably, one or more light sources <NUM> couple light into the light guide <NUM> at one or both opposing end surfaces of the light guide <NUM>. One or more light sources <NUM> may couple light into one end surface of the optical light guide <NUM>.

The light coupled into the light guide <NUM> is transmitted along the longitudinal extension <NUM> of the light guide <NUM> by means of total internal reflection (TIR) at external boundary surfaces of the optical light guide <NUM>. The optical light guide <NUM> is preferably solid and may be made of a glass material or a transparent plastic material, in particular of an acrylic material like polymethylmethacrylate (PMMA) or of polycarbonate (PC). These materials have a good optical clarity, good mechanical properties, and very little natural scintillation response to ionizing radiation. Due to the restricted diameter of the optical light guide <NUM>, a light guide <NUM> made of the mentioned materials is flexible and, therefore, can follow the contour or design line of the power tool <NUM> and the tool housing <NUM>, respectively.

The optical light guide <NUM> may comprise decoupling elements <NUM> located along at least part of the longitudinal extension <NUM> of the light guide <NUM>. The decoupling elements <NUM> are designed to couple out at least part of the coupled-in light <NUM> in a direction <NUM> that is essentially perpendicular to the longitudinal extension <NUM> of the light guide <NUM>. The decoupling elements <NUM> act as virtual light sources through which the light <NUM> is coupled out of the optical light guide <NUM> in the direction <NUM>.

In the embodiment of <FIG>, the optical light guide <NUM> is provided with a few individual decoupling elements <NUM> (having sizes in the range of millimetres) that are arranged at a relatively large distance from each other. Such an arrangement of decoupling elements <NUM> results in an appearance with a multitude of discrete virtual light sources for an observer. Alternatively, the optical light guide <NUM> could also be provided with a plurality of smaller decoupling elements (having sizes in the range of micrometres) arranged very close to each other. Such an arrangement of smaller decoupling elements creates an almost homogeneous appearance of the emitted light for the observer, so that it appears as if the entire outer boundary surface <NUM> of the light guide <NUM> was illuminated homogeneously.

The decoupling elements <NUM> can comprise prisms, inside the optical light guide <NUM> or on the outer boundary surface <NUM> of the light guide <NUM>. A roughening on light reflecting surfaces of the decoupling elements <NUM> and/or on the outer boundary surfaces <NUM> of the light guide <NUM> through which the light <NUM> is coupled out of the light guide <NUM> can provide for an additional scattering and homogenisation of the out-coupled light <NUM>.

In order to increase the efficiency of the elongated light emitting device <NUM>, the decoupling elements <NUM> can be designed and located at or in the optical light guide <NUM> in such a manner as to couple out the at least part of the coupled-in light <NUM> into a <NUM>°-space to one side of the optical light guide <NUM>, preferably towards the environment surrounding the tool housing <NUM>. In <FIG> the <NUM>°-space into which the light <NUM> is emitted, is located below the optical light guide <NUM>. Almost all the light coupled into the optical light guide <NUM> is coupled out of the light guide <NUM> in the direction <NUM> in which it can be seen by an observer. Almost no light is coupled out of the light guides <NUM> towards the tool housing <NUM>, where it would not be seen by an observer.

In order to further enhance the efficiency of the elongated light emitting device <NUM>, it is suggested that a bundling optic <NUM> is arranged between the light source <NUM> and the optical light guide <NUM>, into which the light source <NUM> couples at least part of its emitted light <NUM>. The bundling optic <NUM> is designed to bundle at least part of the light <NUM> emitted by the light source <NUM> and to couple a larger proportion of the emitted light <NUM> into the optical light guide <NUM> than if the bundling optic <NUM> was not present. It can be seen that the bundling optic <NUM> surrounds the light source <NUM> on three sides, thereby gathering a very large amount of the light <NUM> emitted by the light source (LED) <NUM> into a <NUM>°-space adjacent to a light emitting surface of the LED <NUM>. The bundling optic <NUM> focusses the light emitted by the LED <NUM> in a point or plane. The point or plane preferably lies on an end surface of the optical light guide <NUM>.

In the embodiment of <FIG>, an additional deflection element <NUM> is provided, which deflects the focussed light <NUM> from the bundling optic <NUM> towards an end surface of the optical light guide <NUM>. The deflection element <NUM> may comprise a mirror surface or as prism made of solid transparent material and having a total internal reflection (TIR) surface <NUM>. In this embodiment, the point or plane where the bundling optic <NUM> focusses the light, preferably lie on the mirror surface or the TIR surface <NUM>. Of course, the deflections element <NUM> could form an integral part together with the bundling optic <NUM> or the optical light guide <NUM>.

The elongated light emitting device <NUM> may have almost any cross sectional form, including but not limited to: square, rectangular, and polygonal. However, according to a preferred embodiment, the EL wire <NUM> or the optical light guide <NUM> has a round or oval cross section. Such EL wires <NUM> emit light particularly homogenously. Such optical light guides <NUM> propagate the in-coupled light <NUM> by means of TIR particularly efficiently. No so-called hot spots (areas in which light rays accumulate and thus provide a particularly large brightness) are formed in such EL wires <NUM> or optical light guides <NUM>.

The elongated diffusing lens <NUM> shown in <FIG> and <FIG> has a longitudinal extension <NUM>. The diffusing lens <NUM> may have a round, oval, square, rectangular or polygonal cross section. Preferably, the diffusing lens <NUM> has a cross sectional form of a segment of such a cross section, in particular of a semicircle (see <FIG>). The diffusing lens <NUM> may be made of glass, a transparent plastic material or a rubber material. The diffusing lens <NUM> may have any colour in order to give the emitted light <NUM> a desired colour. The diffusing lens <NUM> is preferably made of a solid material. It may have a diffusing structure, e.g. a micro structure on one or more of its external surfaces through which the light <NUM> is transmitted. A plurality of discrete light sources <NUM>, preferably in the form of LEDs, are arranged spaced apart from each other along the longitudinal extension <NUM> of the diffusing lens <NUM> so that they emit light <NUM> substantially transversely to the longitudinal extension <NUM> of the diffusing lens <NUM> therethrough. When passing through the diffusing lens <NUM>, the light <NUM> emitted by the LEDs <NUM> is scattered to such an extent that a light emitting side <NUM> of the diffusing lens <NUM>, which preferably extends opposite the light sources <NUM> over at least part of the longitudinal extension <NUM> of the diffusing lens <NUM>, is uniformly illuminated. On the light emitting side <NUM>, the discrete light sources <NUM> that emit the light <NUM> through the diffusing lens <NUM> are no longer recognisable. Instead, the light emitting side <NUM> of the diffusing lens <NUM> emits a homogeneous light distribution. The light emitting side <NUM> emits the light <NUM> in a direction <NUM> essentially perpendicular to the longitudinal extension <NUM> of the elongated diffusing lens <NUM>. An optic element, similar to the bundling optic <NUM> of <FIG>, may be located between one or more of the LEDs <NUM> and the light entry surface <NUM> of the diffusing lens <NUM>. The optic element preferably broadens the light bundle emitted by the LEDs <NUM>.

It is suggested that the at least one light source <NUM>, <NUM> is designed to emit light <NUM>, <NUM> of at least two different colours. Similarly, the power tool <NUM> may comprise at least two EL wires <NUM> or light sources <NUM>, <NUM> which emit light <NUM>, <NUM> of different colours. Preferably, the colour of the light <NUM>, <NUM>, <NUM> emitted by the at least one elongated light emitting device <NUM> depends on a current operation status of the hand-held power tool <NUM>, comprising but not limited to one or more of:.

The hand-held power tool <NUM> may comprise control means (e.g. a switch, button, dial, etc.) accessible by the user of the power tool <NUM> or other people, for manually setting the colour of the light <NUM> emitted by the EL wire <NUM> or the light source <NUM> by a user of the power tool <NUM>. Alternatively, the control means may comprise a radio receiver for receiving respective control signals containing information about a set colour from a mobile device, e.g. from a mobile phone or a tablet PC on which a dedicated application or computer program is executed which permits the user or other people to set the colour of the emitted light <NUM> to a desired value.

Additionally or alternatively, the electroluminescent wire <NUM> or the at least one light source <NUM>, <NUM> is designed to emit light <NUM>, <NUM> continuously or intermittently at a certain frequency. Preferably, whether the electroluminescent wire <NUM> or the at least one light source <NUM>, <NUM> emits light <NUM>, <NUM> continuously or intermittently and/or the frequency of the intermittently emitted light <NUM>, <NUM> depends on a current operation status of the hand-held power tool <NUM>, comprising but not limited to one or more of:.

Claim 1:
Hand-held power tool (<NUM>), comprising
a tool housing (<NUM>),
a working element (<NUM>) protruding from the tool housing (<NUM>) and designed to perform a working movement (<NUM>) during an intended use of the power tool (<NUM>),
a motor (<NUM>) located inside the tool housing (<NUM>) and designed to drive the working element (<NUM>) to perform the working movement (<NUM>) during the intended use of the power tool (<NUM>), and
at least one elongated light emitting device (<NUM>) having a longitudinal extension (<NUM>) and located at least partially on an external surface of the tool housing (<NUM>),
wherein the at least one elongated light emitting device (<NUM>) is designed to emit light along at least part of its longitudinal extension (<NUM>) in a direction (<NUM>; <NUM>) that is essentially perpendicular to the longitudinal extension (<NUM>) of the elongated light emitting device (<NUM>),
characterized in that the power tool (<NUM>) further comprises
at least one elongated holding arrangement (<NUM>) made of a transparent material and adapted for receiving and surrounding at least part of the elongated light emitting device (<NUM>) and for being attached to the tool housing (<NUM>).