Patent Description:
Food preparation using a radiation grill apparatus is becoming increasingly popular, for example because the indirect transfer of heat to the food support member such as a grill member or the like causes the food on the food support member to be cooked in a more controlled manner, e.g. with reduced risk of burning, smoke generation and so on.

For example, <CIT> discloses a cooking apparatus capable of effectively utilizing thermal energy of a heating unit to heat food, which includes a cabinet opened at a top surface thereof to provide an opening over which food to be cooked is laid. A grill unit is seated in the opening of the cabinet so as to support the food over the opening. A heating unit is provided in the cabinet so that a front surface thereof faces the grill unit to radiate thermal energy to the grill unit. A plurality of reflecting members are provided at predetermined positions around a rear surface of the heating unit, and are installed to be spaced apart from each other by a predetermined gap to provide an air layer between the reflecting members. The construction of the cooking apparatus allows far infrared rays radiated from a rear surface of the heating unit to be reflected to a front of the heating unit, in addition to preventing heat from being transmitted from the heating unit to a rear portion of the heating unit due to an air layer provided between the reflecting members. Accordingly, most of the thermal energy generated from the heating unit may be used for cooking the food.

However, a drawback with such a cooking apparatus is that when opposing sides, i.e. front and back sides, of the cabinet or housing contain such heating units, e.g. infrared (IR) radiation sources to ensure uniform heating of a food support member such as a grill unit, the user of the apparatus tends to look directly at one of the heating units during use of the apparatus. This causes uncomfortable glare for the user. This may be overcome by providing the user with special glasses to wear, but this requires the user to comply with user instructions, and such compliance cannot be guaranteed, for example because the user dislikes wearing such glasses.

For another example, <CIT> discloses a radiation grill with only one radiation heater at one side, which would prevent glare issue while the user would not look directly at the heating unit. However, the drawback is obvious: the heat distribution is quite uneven at its food support member, unlike a grill with two light sources at front and back sides respectively for greatly improving the uniformity of heating distribution.

Another possible solution would be to adjust the spectral composition of the radiation sources to reduce the perceived glare, but this may negatively impact the cooking performance of the apparatus, or, in case of the spectral composition shifting into the invisible part of the infrared spectrum, yield a less user-friendly radiation grill apparatus as the heating of the food becomes invisible, which potentially even can be unsafe as overexposure to such infrared radiation cannot be seen.

The present invention seeks to provide a radiation grill apparatus according to the opening paragraph in which user glare is reduced without significantly affecting the cooking performance of the radiation grill apparatus.

According to the invention, there is provided a radiation grill apparatus comprising a housing having opposing sides and a food support member on said housing, the housing comprising an infrared radiation source arrangement along one of said opposing sides only and arranged to direct a portion of said infrared radiation onto the food support member such as to create a heat distribution across the food support member; a drip collection member facing the food support member; and a reflector arrangement arranged to redirect a further portion of said infrared radiation onto the food support member such as to improve the homogeneity of said heat distribution, said reflector arrangement comprising a first parabolic reflector arranged to redirect part of said further portion of infrared radiation towards an end region of the food support member distal to the infrared radiation source arrangement; and further comprising a further parabolic reflector arranged adjacent to an end point of the first reflector distal to said food support member, said further parabolic reflector being arranged to redirect part of said further portion of infrared radiation towards a central region of the food support member.

The provision of an infrared radiation source arrangement along one of the opposing sides only of the housing, typically the side of the housing facing the user when the radiation grill apparatus is in use ensures that the user cannot directly looking at the infrared radiation source arrangement as this arrangement is blocked from view by the housing. In other to compensate for the inhomogeneity in the energy distribution across the food support member resulting from the presence of infrared radiation source arrangement along only one of the opposing sides of the housing, a reflector arrangement comprising a plurality of reflector portions is provided in which different reflector portions redirect incident radiation from the infrared radiation source arrangement towards different portions of the food support member. In this manner, a radiation grill apparatus is provided with comparable cooking characteristics in terms of heat distribution uniformity across the food support member to prior art radiation grill apparatuses having infrared radiation sources on opposing sides of the housing whilst preventing the user of such an apparatus being exposed to glare.

At this point it is noted that although <CIT> discloses a cooking apparatus with a reflector arrangement comprising a plurality of reflectors, these reflectors are simply arranged to reflect incident light back towards the food support member (here the grill unit) without aiming the reflected light at particular regions of the food support member. In other words, this prior art citation is entirely silent about providing a reflector arrangement for the purpose of improving the homogeneity of the thermal energy distribution across the surface of the food support member.

In an embodiment, the reflector arrangement is dimensioned such that the drip collection member is shielded from direct exposure to the infrared radiation by the reflector arrangement. This has the further advantage that smoke generation caused by overheating of the matter, e.g. oils, collected in the drip tray due to direct exposure to the infrared radiation is prevented, thereby further improving the user friendliness of the radiation grill apparatus. Preferably, the reflector arrangement is dimensioned such that the reflector arrangement does not interfere with the drip collection by said drip collection member as this reduces the amount of cleaning a user has to perform after use of the radiation grill apparatus as such dimensioning ensures that the reflector arrangement is not soiled by fluids dripping from the food during use of the radiation grill apparatus.

In a preferred embodiments, the reflector portions are mathematically discrete portions of a single reflector body, e.g. a reflector body having discrete (discontinuous) surface portions for ease of manufacturing and assembly. Alternatively, The reflector portions may be discrete reflector elements as this facilitates more freedom in aiming of different portions of the infrared radiation to different regions of the food support member at the cost of an apparatus that is more complex to manufacture and assemble. The discrete reflector elements may be spaced apart such as an air gap exists between the discrete reflector elements in order to establish an air flow around the discrete reflector elements in order to prevent their overheating.

According to the invention, the plurality of reflector portions comprises a first parabolic reflector arranged to redirect part of said further portion of infrared radiation towards an end region of the food support member distal to the infrared radiation source arrangement. The use of a parabolic reflector has the advantage that a substantially homogeneous heat distribution can be achieved across the end region of the food support member, i.e. a region distal to the infrared radiation source arrangement.

The first parabolic reflector preferably has a shape defined relative to an axis extending through the infrared radiation source arrangement and an end point of the food support member distal to said infrared radiation source arrangement to achieve such a homogeneous heat distribution.

In an embodiment, this shape obeys the equation y<NUM> = <NUM> p*x, in which x is the axis extending through the infrared radiation source arrangement and the end point of the food support member distal to said infrared radiation source arrangement, y is an axis perpendicular to said x-axis and p is a constant defining an aperture of the first parabolic reflector. If the parabolic reflector has such a shape a particularly good approximation of a homogeneous heat distribution across the end portion of the food support member is achieved.

The first parabolic reflector preferably is dimensioned such that an end point of the parabolic reflector proximal to the food support member does not block direct illumination by the infrared radiation source arrangement of any part of a major surface of the food support member facing the infrared radiation source arrangement. This ensures optimal efficiency of the infrared radiation source arrangement in heating the food support member.

According to the invention, the plurality of reflector portions may further comprise a further parabolic reflector arranged adjacent to an end point of the first parabolic reflector distal to said food support member, said further parabolic reflector being arranged to redirect part of said further portion of infrared radiation towards a central region of the food support member in order to improve the homogeneity of the heating of the food support member by the infrared radiation source arrangement.

The further parabolic reflector may have a shape obeying the equation y'<NUM> = <NUM> p'*x', in which x' is an axis extending through the infrared radiation source arrangement and a point of minimum intensity of the heat distribution across the food support member produced by the infrared radiation source arrangement and the first parabolic reflector, y' is an axis perpendicular to said x'-axis and p' is a constant defining an aperture of the further parabolic reflector. By aiming the output of the further parabolic reflector at a point of minimum intensity resulting from the combination of thermal energy directly aimed at the food support member by the infrared radiation source arrangement and reflected towards the food support member by the first parabolic reflector, a marked improvement in the homogeneity of the heat distribution across the food support member is achieved.

The further parabolic reflector may be dimensioned such as to block direct illumination of the drip collection member by the infrared radiation source arrangement in order to prevent overheating or burning of the contents of the drip collection member as previously explained.

In an embodiment, the plurality of reflector portions further comprises a planar mirror arranged to redirect part of said further portion of infrared radiation towards an end region of the food support member proximal to the infrared radiation source arrangement to further improve the homogeneity of the heat distribution across the food support member. Such a planar mirror when present may be arranged such that the further parabolic reflector is located in between the first parabolic reflector and the planar mirror.

The infrared radiation source arrangement may comprise one or more discrete infrared radiation sources. The number of discrete infrared radiation sources is typically chosen to ensure that the food support member is exposed to sufficient thermal energy for cooking the food supported thereon.

The housing may comprise a cavity housing the infrared radiation source arrangement and the reflector arrangement arranged around part of said infrared radiation source arrangement. The positioning of the infrared radiation source arrangement in such a cavity further reduces the risk of a user of the radiation grill apparatus being directly exposed to infrared radiation, i.e. to glare.

Embodiments of the invention are described in more detail and by way of nonlimiting examples with reference to the accompanying drawings, wherein:.

<FIG> schematically depicts a cross-sectional view of a radiation grill apparatus <NUM> according to an embodiment of the present invention. The radiation grill apparatus <NUM> comprises a housing <NUM> including opposing sides <NUM>, <NUM>. The housing <NUM> may comprise a cavity <NUM> proximal to the first side <NUM>. The housing <NUM> may be made of any suitable material, e.g. a metal, metal alloy, plastics material or combination thereof. Proximal to the first side <NUM>, e.g. within the cavity <NUM>, the housing <NUM> contains an infrared radiation source arrangement <NUM> comprising one or more infrared radiation sources, e.g. one or more infrared lamps. The infrared radiation source arrangement <NUM> is arranged to directly irradiate a food support member <NUM> of the opening of the housing <NUM> in between the opposing sides <NUM>, <NUM>. The food support member <NUM> may take any suitable shape, e.g. a grill unit or the like comprising a plurality of apertures through which liquids dripping from a food product being cooked on the food support member <NUM> can be gravity fed as indicated by the dashed arrows into a drip collection member <NUM> of the radiation grill apparatus <NUM> opposing the food support member <NUM>. Such a drip collection member <NUM> may be a drip tray or the like, and preferably is removable from the radiation grill apparatus <NUM> for cleaning purposes.

The radiation grill apparatus <NUM> further comprises a reflector arrangement <NUM> including a plurality of reflector portions <NUM>, <NUM> in between the infrared radiation source arrangement <NUM> and the housing <NUM> such that direct irradiation of the food support member <NUM> by the infrared radiation source arrangement <NUM> is not impeded by the reflector arrangement <NUM>. The reflector portions <NUM>, <NUM> may be made of any suitable material, e.g. a reflective material such as a reflective metal or metal alloy, for example aluminium or steel, or a material carrying a reflective coating, e.g. a glass mirror or the like. The reflector portions <NUM>, <NUM> preferably form part of a single reflector body for ease of manufacturing and assembly, i.e. are mathematically discrete reflector portions, but alternatively may be physically discrete reflectors, which may be spatially separated from each other and/or from the infrared radiation source arrangement <NUM> to allow an airflow around the reflector portions <NUM>, <NUM> to reduce the risk of overheating of the reflector portions <NUM>, <NUM> by incident infrared radiation from the infrared radiation source arrangement <NUM>. The reflector portions <NUM>, <NUM> are aimed at different regions of the food support member <NUM> such as to improve the homogeneity of the heat distribution generated by the infrared radiation source arrangement <NUM> across the food support member <NUM>.

This is explained in further detail with the aid of <FIG>, which schematically depicts an example positioning of the infrared radiation source arrangement <NUM> within the radiation grill apparatus <NUM> at a height h and a distance d from a food support member <NUM> with length <NUM>, thus causing the food support member <NUM> to be directly illuminated by the portion <NUM> of infrared radiation under a range of angles θ. This causes a heat distribution across the food support member <NUM> as shown by curve IR in <FIG>, in which the X-axis depicts a length coordinate of the food support member from <NUM> to <NUM>, in which <NUM> is the end point of the food support member <NUM> proximal to the infrared radiation source arrangement <NUM> and l is the opposing end point of the food support member <NUM> distal to the infrared radiation source arrangement <NUM>. The Y-axis depicts the heat intensity (in arbitrary units). From this curve IR, it can be seen that an infrared radiation source arrangement <NUM> at a single side only of the housing <NUM> causes a decrease of heat intensity across the food support member <NUM> of the radiation grill apparatus <NUM> with increasing distance from the infrared radiation source arrangement <NUM>.

In order to achieve the ideal (homogeneous) heat distribution HD across the food support member <NUM>, the reflector arrangement <NUM> must generate a heat distribution across the food support member as symbolized by the curve R, as IR + R = HD. However, in practice it is impossible from an engineering perspective to achieve a reflector producing the heat distribution as symbolized the curve R across the food support member <NUM>. Moreover, providing a single reflector approximating this heat distribution requires a reflector having a complex design, which is also undesirable from an engineering perspective. Therefore, in accordance with the teachings of the present invention, a reflector arrangement <NUM> is provided comprising multiple reflector portions aimed at different regions of the food support member <NUM> in order to approximate the curve R, which is easier to design and manufacture.

<FIG> schematically depicts a cross-sectional view of a part of the reflector arrangement <NUM> within the radiation grill apparatus <NUM> for reflecting a part of the infrared radiation generated by the infrared radiation source arrangement <NUM> that is not directly incident on the food support member <NUM> towards a region of the food support member <NUM> in order to improve the homogeneity of the heat distribution across the food support member <NUM> as generated by the infrared radiation source arrangement <NUM> at one side of the housing <NUM> only as previously explained. The reflector arrangement <NUM> in this embodiment comprises a parabolic reflector <NUM> obeying the function y<NUM> = <NUM> p*x, in which x, y are coordinates in a coordinate system defined by an x-axis extending through the centre of the infrared radiation source arrangement <NUM> and an end point <NUM> of the food support member distal to the infrared radiation source arrangement <NUM> and an y-axis arranged perpendicular to the x-axis. The infrared light source arrangement <NUM> typically is positioned in the focus of the parabolic reflector <NUM>, i.e. at distance p/<NUM> from the vertex of the parabolic reflector. The variable p defines the degree of curvature of the parabolic reflector <NUM>, and may be chosen in a range of <NUM>/<NUM> * l to <NUM>/<NUM> * <NUM>, in which l is the width of the food support member <NUM>.

The parabolic reflector portion <NUM> extends between a first point <NUM> proximal to the food support member <NUM> and an opposing point <NUM> distal to the food support member <NUM>. Preferably, the first point <NUM> is chosen such that the parabolic reflector portion <NUM> does not extend into the infrared radiation emitted by the infrared radiation source arrangement <NUM> under the range of angles θ, i.e. the parabolic reflector portion <NUM> does not block part of the food support member <NUM> from being directly illuminated by the infrared radiation source <NUM>.

The parabolic reflector portion <NUM> is arranged to illuminate regions i0 and i1 of the food support member <NUM> with a portion <NUM> of infrared radiation originating from the infrared radiation source arrangement <NUM> as reflected by the parabolic reflector portion <NUM>. This yields an improved heat distribution across the food support member <NUM> as depicted in <FIG>, in which HD = IR + R1, with R1 depicting the heat distribution created by the portion <NUM> of infrared radiation reflected by the parabolic reflector portion <NUM>. As can be seen from the curve HD, this curve now contains a peak in the heat distribution in the centre of the food support member <NUM>. This is acceptable, as most users of the radiation grill apparatus <NUM> tend to position the food product to be cooked in the centre of the food support member <NUM>, and the central region of the food support member <NUM> is sufficiently heated by the infrared radiation source arrangement <NUM> and the reflector arrangement <NUM> as demonstrated by this spike in the heat distribution across the food support member <NUM>. However, as indicated by the arrow in <FIG>, this heat distribution still contains a valley at location or point <NUM> of the food support member <NUM>, which ideally should be compensated for.

To this end, the reflector arrangement <NUM> further comprises a further parabolic reflector portion <NUM> adjacent to the first reflector portion <NUM> as schematically depicted in <FIG>. The first parabolic reflector portion <NUM> and the further parabolic reflective portion <NUM> preferably form part of a single reflector body but alternatively may be physically discrete reflectors, which may be spatially separated from each other, e.g. by a small air gap, to ensure that air can flow around the respective reflector portions <NUM>, <NUM> for cooling purposes. Alternatively, the first parabolic reflector portion <NUM> and the further parabolic reflective portion <NUM> may be abutting, i.e. end points <NUM> and <NUM> coincide. The further parabolic reflector portion <NUM> obeys the function y'<NUM> = <NUM> p'*x', in which x', y' are coordinates in a coordinate system defined by an x'-axis extending through the centre of the infrared radiation source arrangement <NUM> and the intermediate point <NUM> on the food support member <NUM> at which the minimum in the heat distribution as generated by the infrared radiation source arrangement <NUM> and the first parabolic reflector <NUM> is located and an y'-axis arranged perpendicular to the x'-axis. The infrared radiation source <NUM> typically is positioned at a distance p'/<NUM> from the vertex of the further parabolic reflector portion <NUM>, i.e. in the focus of this reflector portion. The variable p' defines the degree of curvature of the further parabolic reflector <NUM>, and may be chosen in a range of p' = <NUM>/<NUM> * l to <NUM>/<NUM> * l, in which l is the width of the food support member <NUM>.

The further parabolic reflector portion <NUM> extends between a first point <NUM> proximal to the food support member <NUM> and an opposing point <NUM> distal to the food support member <NUM>. Preferably, the second point <NUM> is chosen such that the further parabolic reflector portion <NUM> does not extend into the infrared radiation emitted by the infrared radiation source arrangement <NUM> under the range of angles θ, i.e. the further parabolic reflector portion <NUM> does not block part of the food support member <NUM> from being directly illuminated by the infrared radiation source <NUM>. More preferably, the second point <NUM> is chosen such that the further parabolic reflector portion <NUM> does not extend into the drip path between the food support member <NUM> and the drip collection member <NUM>, thus avoiding excessive soiling of the further parabolic reflector portion <NUM> by such drips. The further parabolic reflector portion <NUM> may be dimensioned such that direct illumination of the contents of the drip collection member <NUM> by the infrared radiation source arrangement <NUM>, i.e. light emitted beyond the range of angles α, is prevented. In other words, the light emitted under the range of angles α is not directly incident on the drip collection member <NUM>.

The further parabolic reflector portion <NUM> is arranged to illuminate region i2 of the food support member <NUM> around the intermediate point <NUM> with a portion <NUM> of infrared radiation originating from the infrared radiation source arrangement <NUM> as reflected by the further parabolic reflector portion <NUM>. This yields an improved heat distribution across the food support member <NUM> as depicted in <FIG>, in which HD = IR + R1 +R2, with R2 depicting the heat distribution across the region i2 of the food support member <NUM> as created by the portion <NUM> of infrared radiation reflected by the further parabolic reflector portion <NUM>. The further parabolic reflector portion <NUM> generates an almost uniform heat distribution around the valley position <NUM> in the heat distribution generated by IR + R1 as previously explained, thereby further improving the approximation of the homogeneity of the heat distribution across the food support member <NUM>. In fact, the reflector arrangement <NUM> consisting of the first parabolic reflector portion <NUM> and the further parabolic reflector portion <NUM> was found to provide a satisfactory heat distribution across the entirety of the food support member <NUM>.

Nevertheless, in a further embodiment as schematically depicted in <FIG>, the reflector arrangement <NUM> further comprises a planar reflector portion <NUM>, e.g. a planar mirror or the like to further improve the homogeneity of the heat distribution across the food support member <NUM>, in particular across a region i3 of the food support member <NUM> proximal radiation source arrangement <NUM>, as schematically depicted in <FIG>, in which it can be seen that a portion <NUM> of infrared radiation as generated with the infrared radiation source arrangement <NUM> is reflected by the planar reflector portion <NUM> towards the region i3 of the food supporting member <NUM>. As previously explained, the planar reflector portion <NUM> preferably forms part of a single reflector body further including the first parabolic reflector <NUM> and the second parabolic reflector <NUM>, although alternatively the planar reflector portion <NUM> may be a physically discrete reflector, which (optionally) may be spatially separated from the second parabolic reflector <NUM>. The planar reflector portion <NUM> is typically arranged such that the further parabolic reflector portion <NUM> is positioned in between the first parabolic reflector portion <NUM> and the planar reflector portion <NUM>. Preferably, the planar reflector portion <NUM> is dimensioned such that the planar reflector portion <NUM> does not interfere with the drip path between the food support member <NUM> and the drip collection member <NUM> of the radiation grill apparatus <NUM> to prevent excessive soiling of the planar reflector portion <NUM>. As will be readily understood by the skilled person, this means that in this embodiment the further parabolic reflector portion <NUM> may be smaller, i.e. having a shorter length between its end points <NUM> and <NUM>, compared to the embodiment schematically depicted in <FIG>.

The resulting heat distribution across the food support member <NUM> is schematically depicted in <FIG>, in which HD = IR + R1 + R2 + R3, with R3 depicting the heat distribution across the region i3 of the food support <NUM> as generated with the planar reflector member <NUM>. Consequently, a heat distribution across the food support member <NUM> is achieved by the combination of the reflector arrangement <NUM> and the infrared radiation source arrangement <NUM> that has a markedly improved homogeneity compared to a heat distribution across the full support member <NUM> achieved by the infrared radiation source arrangement <NUM> in isolation.

Hence, embodiments of the present invention disclose a radiation grill apparatus <NUM> comprising an infrared radiation source arrangement <NUM> on one side only of the housing <NUM> of the radiation grill apparatus <NUM>, in which a reflector arrangement <NUM> comprising a combination of parabolic reflector portions and/or planar reflector portions is positioned around a part of the infrared radiation source arrangement <NUM> to improve the homogeneity of the heat distribution across the food support member <NUM> of the radiation grill apparatus <NUM>. The different reflector portions preferably combine to form a single reflector body having different portions or regions defined by different mathematical functions (e.g. the body cannot be described using a single or continuous mathematical function) or may be provided as physically discrete reflectors. It should be understood that embodiments of the present invention are not limited to the example embodiments disclosed in the present application; any suitable combination of parabolic reflector portions and/or planar reflector portions may be used to improve such homogeneity in the heat distribution across the food support member <NUM>.

Claim 1:
A radiation grill apparatus (<NUM>) comprising a housing (<NUM>) having opposing sides (<NUM>, <NUM>) and a food support member (<NUM>) on said housing, the housing comprising:
an infrared radiation source arrangement (<NUM>) along one of said opposing sides (<NUM>) only and arranged to direct a portion of said infrared radiation onto the food support member such as to create a heat distribution across the food support member;
a drip collection member (<NUM>) facing the food support member; and
a reflector arrangement (<NUM>) arranged to redirect a further portion of said infrared radiation onto the food support member; characterized in that,
the said reflector arrangement (<NUM>) comprises a first parabolic reflector (<NUM>) arranged to redirect part (<NUM>) of said further portion of infrared radiation towards an end region (i0, i1) of the food support member (<NUM>) distal to the infrared radiation source arrangement (<NUM>); and
said reflector arrangement (<NUM>) further comprises a further parabolic reflector (<NUM>) arranged adjacent to an end point (<NUM>) of the first reflector (<NUM>) distal to said food support member (<NUM>), said further parabolic reflector (<NUM>) being arranged to redirect part (<NUM>) of said further portion of infrared radiation towards a central region (i2) of the food support member (<NUM>).