AIRFRYING SYSTEM AND METHOD

Abstract

A system for preparing food that includes a holder for holding the food and an apparatus. The apparatus includes a processing chamber that is RF-impermeable and air-impermeable, a holding device for holding the holder inside the processing chamber, an RF-antenna to radiate RF-energy to the inside of the processing chamber for heating the food inside the holder, a fan for circulating the air in the processing chamber through an air-permeable side and through the holder, and a heater to provide heat to the circulated air. The fan and the heater are to air fry the food inside the holder. The processing chamber includes a top shell having a top inner space and a top rim forming an access opening to the top inner space, and a bottom shell having a bottom inner space and a bottom rim forming an access opening to the bottom inner space. In a closed position, the top shell and the bottom shell are to envelop an interior space that includes the top inner space and the bottom space. The processing chamber is shaped such that the RF-wave has a node substantially at the top rim and/or the bottom rim in the closed position.

Claims

1-40. (canceled)

41. A system for preparing food, the system comprising: an RF-impermeable layer; a food holder for holding the food, the food holder including an air-permeable side; and an apparatus that includes: a processing chamber that is RF-impermeable and air-impermeable; a holding mechanism for holding the food holder inside the processing chamber; an RF-antenna to radiate RF-energy to an inside of the processing chamber for heating the food inside the food holder; a fan to circulate air in the processing chamber through the air-permeable side and through the food holder; and a heater arranged to provide heat to the circulated air, wherein: the fan and the heater are arranged for air frying the food inside the holder, the RF-impermeable layer is air-permeable and at least in use arranged substantially parallel to the air-permeable side of the food holder, the RF-impermeable layer is to separate the processing chamber in a first area susceptible to RF-energy from the RF-antenna and a second area shielded from RF-energy from the RF-antenna; and the fan is arranged in the second area.

42. The system of claim 41, wherein a provision of RF-energy to the food inside the food holder is independent of a provision of heated air to the food inside the food holder.

43. The system of claim 41, wherein the air-permeable side is to allow a vertical stream of air through the food holder.

44. The system of claim 41, wherein the air-permeable side of the holder is an air-permeable bottom side.

45. The system of claim 41, wherein the food holder comprises the RF-impermeable layer.

46. The system of claim 45, wherein the RF-impermeable layer is a top-side of the holder.

47. The system of claim 41, wherein: the RF-impermeable layer is a bottom-side of the food holder, and the RF-impermeable layer and the air-permeable side are integrated.

48. The system of claim 41, wherein the holding mechanism is at least partly RF-impermeable for in use together with the RF-impermeable layer forming an RF separation in the processing chamber.

49. The system of claim 41, wherein the heater is arranged in the second area.

50. The system of claim 41, wherein the heater is at least partly RF-impermeable for in use together with the RF-impermeable layer forming an RF-separation in the processing chamber.

51. The system of claim 41, further comprising: an RF-source to provide RF-energy to the RF-antenna; a motor to drive the fan; a heater source to provide energy to the heater; and a controller to control the RF-source, the motor, and the heater independently in such a manner to control an amount of RF-energy from the RF-source, a number of revolutions of the motor, and an amount of radiated heat from the heater.

52. The system of claim 41, wherein the food holder comprises a food basket.

Description

DRAWINGS

[0064] The invention will be apparent from and elucidated further regarding the embodiments described by way of example in the following description and with reference to the accompanying drawings, in which:

[0065] FIG. 1 schematically shows a cross-section of a first embodiment of the system according to the invention;

[0066] FIG. 2 schematically shows another cross-section of a first embodiment of the system according to the invention;

[0067] FIG. 3 schematically shows a cross-section of a processing chamber of a first embodiment of the system according to the invention;

[0068] FIG. 4A schematically shows a second cross-section of a processing chamber of a first embodiment of the system according to the invention;

[0069] FIG. 4B schematically shows a third cross-section of a processing chamber of a first embodiment of the system according to the invention;

[0070] FIG. 4C schematically shows a fourth cross-section of a processing chamber of a first embodiment of the system according to the invention;

[0071] FIG. 4D schematically shows a fifth cross-section of a processing chamber of a first embodiment of the system according to the invention;

[0072] FIG. 4E schematically shows a sixth cross-section of a processing chamber of a first embodiment of the system according to the invention;

[0073] FIG. 5 schematically shows a cross-section of a second embodiment of the system according to the invention;

[0074] FIG. 6 schematically shows a cross-section of a first embodiment of the apparatus according to the invention;

[0075] FIG. 7 schematically shows a detail of a cross-section of a first embodiment of the apparatus according to the invention;

[0076] FIG. 8 schematically shows a perspective view of a top corner of a first embodiment of the apparatus according to the invention;

[0077] FIG. 9 schematically shows a detail of a cross-section of an RF-antenna of a first embodiment of the apparatus according to the invention;

[0078] FIG. 10A schematically shows a seventh cross-section of a processing chamber 145 of a first embodiment of the system according to the invention;

[0079] FIG. 10B schematically shows an eighth cross-section of a processing chamber of a first embodiment of the system according to the invention;

[0080] FIG. 10C schematically shows a nineth cross-section of a processing chamber of a first embodiment of the system according to the invention;

[0081] FIG. 11 schematically shows a cross-section of a third embodiment of the system according to the invention; and

[0082] FIG. 12 schematically shows a tenth cross-section of a processing chamber of a first embodiment of the system according to the invention.

[0083] The figures are purely diagrammatic and not drawn to scale. In the figures, elements which correspond to elements already described may have the same reference numerals.

DESCRIPTION

[0084] FIG. 1 schematically shows a cross-section of a first embodiment of the system 100 according to the invention. The system comprises an RF-impermeable layer 110, a holder 120, and an apparatus 140. The holder comprises an air-permeable side 121. The apparatus comprises a processing chamber 145, holding means 148, 148′, an RF-antenna 155, 155′, a fan 156 and a heater 157, 157′. The apparatus may further comprise a housing 141 housing all the features of the apparatus.

[0085] The processing chamber of the apparatus may comprise a top shell 146 and a bottom shell 147. The top shell and the bottom shell may be position in a closed position where the top and bottom shells form the RF-impermeable and air-impermeable layer of the processing chamber. The apparatus is shown in a closed position with the holder arranged inside the processing chamber. The holder may comprise a handle 125. The handle may partly stick out of the apparatus for easy removal of the holder when the apparatus or processing chamber is in an open position. The open position of the apparatus is when the top and bottom shell are separated in such a way that the holder may be removed from or positioned in the apparatus, more specifically in the processing chamber. In an alternative embodiment, the holder is kept in the bottom shell when loading and unloading food from the holder. In this alternative embodiment, the holder is only separated from the bottom shell for cleaning purposes. In an alternative embodiment, the top shell and the bottom shell may respectively be a front door and a back shell. In even another embodiment, the top shell and the bottom shell may respectively be a front shell and a back shell. In an embodiment of the holder, the holder comprises a detachable handle 125. The detachable handle provides the advantage of minimizing the number of excessively protruding elements of the holder such that it may easer fit in e.g. a dish cleaner or a cupboard.

[0086] The holding means are arranged inside the processing chamber for arranging or positioning the holder. The holder may be a ring or rectangle, only supporting the outer edge of the holder. The holder may be a layer partly or fully covering the bottom of the holder. This layer may be air-impermeable and/or RF-impermeable. In an alternative embodiment an edge of the top shell couples with the top edge of the holder for forming an RF-enclosed space, while the air-impermeable layer of the processing chamber is separate from the RF-impermeable layer, wherein the air-impermeable layer of the processing chamber is enclosing the RF-impermeable layer of the processing chamber, and wherein the RF-impermeable layer of the processing chamber and the RF-impermeable holder form together the first area. In this alternative embodiment, the air may circulate back in the space between the air-impermeable layer and the RF-impermeable layer.

[0087] The embodiment shows two RF-antennas, but the inventor has also envisioned embodiments using only one RF-antenna. The inventor has also envisioned to use a plurality of RF-antennas for directing the RF-energy in a particular direction, such as in the direction of the food held in the holder. Furthermore, with the use of two or more RF-antennas, at least one RF-antenna can be used for supplying RF-energy and the one or more RF-antenna not supplying RF-energy may be used for measuring or sensing the effectiveness of the RF-energy transmission towards the food in the holder or may be used to determine the characteristics of the food in the holder. For example, to determine the state of the food in the holder, being, e.g., frozen, unfrozen, or partly frozen and partly unfrozen. Also, more specific measurements may be used, such determining if the food is liquid or solid next to the states frozen and unfrozen for even better directing the RF-energy to the right locations inside the food for more even transition of the food from frozen to an unfrozen state and for more evenly cooking of the food as a whole.

[0088] The fan regulates the speed of the air stream. The heater together with the fan regulate the temperature of the air stream. The temperature of the air stream will for example drop if the speed of the air stream is increased, but also if the heater is switched off. The temperature of the air stream may range between to temperatures over 100° C., such as 100 to 250° C., preferably to 150 to 240° C., more preferably below 230° C. The fan and heater are typically arranged for air frying.

[0089] As the fan and heater may be made of materials or have a size and/or shape that reduces, disturbs or weakens the RF-waves from the RF-antenna, the fan and heater are best shielded from the RF-waves. Furthermore, the motion of the fan may worsen the influence of the fan on the RF-waves. The RF-impermeable layer is therefore arranged inside the processing chamber such that a part of the processing chamber is shielded from these one or more RF-antennas and the RF-waves emitted from these one or more RF-antennas, this part of the processing chamber is labelled second area 151. By shielding these parts, the RF-waves may reach the food in the holder undisturbed or less weakened for an improved transfer of RF-energy from the RF-antenna to the food in the holder. The part of the processing chamber exposed to RF-waves is labelled first area 150.

[0090] As the fan and heater are arranged in a RF-shielded area or in a RF low energy area, the air stream generated by the fan and heated by the heater should still be able to reach the food as well as the RF-energy. The fan is arranged such that the fan directs the air stream through the food in the holder via an air-permeable layer and/or air-impermeable side. The fan may blow the air through the food or suck the air through the food. This also allows the fan to alter the direction of the air stream for improved cooking and/or frying of the food from all sides and/or angles.

[0091] The apparatus may comprise a motor 159. The motor may be arranged below the processing chamber. FIG. 1 further shows a vertical axis V of symmetry of the apparatus. The motor may be aligned with this axle of symmetry. In an alternative embodiment, the motor may be arranged more to the backplane of the apparatus for optimizing the balance and/or stability of the apparatus, especially during loading or unloading of the holder having food in the holder. The placement of the motor may counter balance the weight of the holder and the food held in the holder, especially when the holder is resting on the apparatus while not being aligned with the vertical axis V. The apparatus may comprise an axle 164 coupling the motor to the fan providing the advantage of a very simple and failsafe coupling. Alternatively, the motor may be coupled to the fan indirectly providing the advantage of more freedom to position the motor.

[0092] FIG. 2 schematically shows another cross-section of a first embodiment of the system 100 according to the invention. The system comprises an RF-impermeable layer 110, a holder 120, and an apparatus 140. The holder is shown outside the apparatus. In this specific embodiment, the RF-impermeable layer 110 and the air-permeable bottom side 121 of the holder are integrated. This has the technical effect, when the holder is removed, that the heater and the fan may become easily accessible for cleaning.

[0093] FIG. 3 schematically shows a cross-section of a processing chamber 145 of a first embodiment of the system according to the invention. The processing chamber is shown without housing and without the holder arranged in the apparatus or processing chamber. This Figure shows a possible location of the RF-antennas. This Figure details the locations where RF-energy may leak from the processing chamber. Leakage may occur at the location of the one or more RF-antennas 155, 155′. Leakage may also occur where the top shell and the bottom shell forming the processing chamber join 144, 144′. A further leakage point may be the axle opening 143 in the processing chamber. The axle opening allows the axle to pass through for driving the fan. The axle opening may be arranged to the bottom shell. This axle may further act as an antenna receiving RF-energy, typically a low amount of RF-energy as this fan is arranged in the second area which is free of RF-energy as much as possible for providing the technical effect described for the invention, worsening the potential leakage along or through the axle of the fan. Typically, the axle comprises a material with low conductive properties for RF-energy in the particular frequencies or frequencies of the RF-energy or RF-waves emitted by the RF-antennas and used for cooking. Also, typically, so called RF-traps are set up around or in the axle to trap the RF-energy and RF-wave inside the processing chamber.

[0094] Leakage typically becomes an issue when RF-waves of a frequency are used outside the ISM band. Although the ISM band is mostly freely available around the world, other frequencies are not. Especially the frequencies around 915 MHz are not free for use in e.g. Europe. This requires that the leakage should be minimized, preferably to levels which makes the system accepted throughout or almost throughout the world.

[0095] All FIG. 4 schematically show a second cross-section of a processing chamber of a first embodiment of the system 100 according to the invention. For all FIG. 4, additionally the holder 120 and the fan 156 are shown arranged inside the apparatus.

[0096] In FIG. 4A the area where the RF-energy may propagate, can propagate, or can predominantly propagate is hatched. This area inside the processing chamber is labelled the first area 150. The boundaries of the first area comprise the sides of the processing chamber and the RF-impermeable layer arranged inside the processing chamber. The length L and the height H of the first area are show in FIG. 4A.

[0097] In FIG. 4B the area where the air may circulate, can circulate, or will predominantly circulate is hatched. It is shown that the hot air may circulate through the whole processing chamber. The invention also comprises embodiments wherein only a part of the processing chamber is used for circulating the hot air for cooking. An exemplary embodiment is where the sides of the processing chamber being RF-impermeable and air-permeable are separated or spaced apart. RF-impermeable material may also have high heat conductive properties. This separation or spacing may be advantageous where materials are used both being RF-impermeable and heat conductive for preventing the outside of the processing chamber becoming hot in use.

[0098] FIG. 4C shows the subtraction of the area hatched in FIG. 4B from the first area, which is the hatched area in FIG. 4A. The result of the subtraction is, predominantly is or substantially is the area where the circulated hot air may get, but where the RF-energy or RF-waves cannot come or are greatly minimized. This resulting area is labelled the second area 151.

[0099] FIG. 4D schematically shows a fifth cross-section of a processing chamber of a first embodiment of the system according to the invention. The arrows in the Figure show a typical airflow A of the air circulating through the food and back along the sides between the holder and the processing chamber. The circulation is maintained with the use of the fan at the bottom of the processing chamber.

[0100] FIG. 4E schematically shows a sixth cross-section of a processing chamber of a first embodiment of the system according to the invention. FIG. 4E is identical to FIG. 4D except for the direction of the airflow A, which is revered in comparison to FIG. 4D.

[0101] FIG. 5 schematically shows a cross-section of a second embodiment of the system 100 according to the invention. Additionally, to the first embodiment, this embodiment also comprises the RF-sources 158 feeding the RF-antennas with energy for emitting RF-waves or RF-energy from the RF-antennas. Further, the system comprises a controller 160 and a motor 159. The motor is arranged for driving the fan. As the motor may emit RF-radiation disturbing the RF-waves, the motor is advantageously arranged outside the processing chamber. The heater may be arranged to the outside the processing chamber or integrated in a side of the processing chamber for providing heat to the air stream inside the processing chamber, such as conducting thermal energy through the side of the chamber. In this embodiment, the heater is arranged inside the processing chamber.

[0102] The controller may be arranged for receiving input from an operator. The controller may be arranged for controlling the heater and the fan for controlling the cooking effect of the hot air passing through or along the food. The controller may be arranged for controlling the RF-source for controlling the amount of RF-energy, the frequency of the RF-waves and/or the RF-mode of the RF-waves for controlling the cooking effect of the RF-energy radiated towards the food. The RF-source may comprise an RF-amplifier, such as a solid-state amplifier, controlling the RF-energy with high precision such as stepless controlling the RF-energy emitted. The RF-source may comprise an RF-signal generator for generating the frequency of the RF-wave.

[0103] The controller may use the settings of the operator for controlling or setting the RF-source, the fan and/or the heater. Additionally, or alternatively, the controller may use sensors for determining the settings of the RF-source, the fan and/or the heater. A sensor may be a temperature sensor, such as an IR-sensor, sensing the temperature of the food inside the holder. A sensor may be a temperature sensor sensing the temperature of the circulated hot air for indirectly determining the temperature of the food in the holder by comparing the measured temperature against the amount of energy introduced by the heater and the air speed generated by the fan. A sensor may be an RF-antenna not emitting RF-energy for determining the RF-energy emitted by another RF-antenna and the effect on the food in the holder. Using multiple RF-antennas as a sensor may provide an accurate image to the controller of the amount of food in the holder, such as the number of kilograms, as well as the texture of the food and/or the state of the food, such as the food being frozen, unfrozen or partly frozen and unfrozen.

[0104] FIG. 6 schematically shows a cross-section of a first embodiment of the apparatus 140 according to the invention. The location of the cross-section is shown in FIG. 1. The cross-section of FIG. 1 is taken vertically, the cross-section of FIG. 6 is taken horizontally. The apparatus comprises a processing chamber 145, which processing chamber may comprise a top shell 146. The apparatus may further comprise a housing 141. The housing typically provides a frame or structure for arranging the elements of the apparatus to each other. The length L and the width W of the first area 150 inside the processing chamber are shown in FIG. 6. The height at which the cross-section is taken is the height which may be designated as unoccupied section inside the processing chamber.

[0105] The dimensions, being length, width and height, of the first chamber highly influence the damping or stimulating of frequencies of the RF-waves and highly influences the mode of the RF-waves.

[0106] The dominant RF-wave in the unoccupied section is a standing RF-wave. The size and/or shape of the first area, typically at least the length and the width, are selected such that one or two standing waves are formed. A standing wave provides a means for efficiently transferring the RF-energy from the RF-antenna to the food. A standing wave may have energy hotspots. A further advantage may be to have two dominant standing waves for more evenly spreading the RF-energy inside the food. To enhance the forming of two dominant standing waves, the length and width of the first area may be selected slightly different.

[0107] The dominant standing RF-wave in the unoccupied section may be an RF-wave having TE-mode 011, TE-mode 111, and/or TM-mode 110. Especially the combination of TE-mode 011 and TE-mode 111 seem beneficial as these modes require substantially the same length and width of the first area for being the dominant standing RF-waves.

[0108] The RF-antenna may operate in a frequency range fully penetrating the food in the holder, wherein the food in the holder has a weight over 2 Kg, preferably 3 Kg, more preferably over 4 Kg. These amounts of food are typically used in commerce and not for home use. The frequency for the RF-waves and the size and/or shape of the processing chamber are to be advantageously selected and sized and/or shaped respectively to accommodate this amount of food in the holder.

[0109] The RF-antenna may operate in a frequency range fully penetrating the food in the holder, wherein the frequency range is below 1 GHz, preferably within the 902 to 928 MHz band or substantially 915 MHz. The amounts of food, as specified above, have to be penetrated by the RF-waves for providing the RF-energy everywhere inside the food. The typically used frequency of 2.45 GHz is not suitable as the penetration depth is only in the range of centimetres, thus not good enough to penetrate food blocks weighing over 2 Kg. Selecting a lower frequency advantageously allows the RF-wave to penetrate the food deeper, instead of only heating the outside layer of the food. If the frequency is selected even such low that the RF-wave traversing through the food is only partially absorbed, the RF-wave may consequently bounce back from the processing chamber and/or RF barrier separating the first and second area for thereafter traversing the food again for heating the food by being absorbed. It provides the advantage that the food is more evenly heated during, e.g., the transition from frozen to unfrozen. This provides the further advantage that the food is less heated with hotspots determined by the standing wave, but also by the more randomized reflections enhancing the evenly spreading of absorbed RF-energy in the food.

[0110] It is an insight of the inventor, based on extensive characterization of various food and conditions, that the frequency range of 902 to 928 MHz has one or more advantages over other frequencies such at the range of 2390 to 2450 MHz. Also, in various countries, this frequency band of 902 to 928 MHz can be used freely, unlicensed band. In many other countries however, very strict regulations apply for that frequency range and provisions have to be taken to prevent electro-magnetic-interference. Hence, selecting a frequency in this range advantageously eases the compliance with those different requirements and still achieves a good performance, especially at 2.45 GHz ISM band worldwide and not only at the 915 MHz band for the Americas. Thus, production is simplified by selecting a frequency in this range, while this frequency range also provides the benefit of high penetration of the food in the holder.

[0111] The dominant RF-waves may have a frequency below 1 GHz, preferably within the 902 to 928 MHz band or substantially 915 MHz, and the dominant RF-waves have at least one, preferably both, a TE-mode 011 and/or a TE-mode 111. Experiments and tests of the inventor have shown that with the before mentioned parameters, the length and width of the processing chamber get in the range of 250 to 380 mm, preferably in the range of 280 to 340 mm, more preferably around 306 mm. This dimension may also refer to a certain size of the RF-impermeable wall of the holder and may be adjusted accordingly to the overall, effective processing chamber. The height of the first area during the experiments and tests was in the range of 180 mm, more specifically 192 mm, while the height of the holder was less than half 60% of the height of the first area. Furthermore, it was assumed that the dielectric constant of air was around 1, of the RF-permeable sides of the holder around 3-10, depending on the material of the holder, such as PTFE, PEEK, fibreglass or ceramics, and of the frozen food around 80, while unfrozen but cold food may be around 3. Typically, as temperature increases, permittivity of the food ends up around 40 for mainly water-based food products, e.g. hot snack food with moist insides, while the crispy crust settle around 80. These dimensions are well suited for holding more substantial amounts of food, especially for commercial use. This embodiment may be valid for compact size general equipment or counter-top equipment, it may be further enhanced by selecting a different length and width for the first area, but still in the range specified for advantageously spreading the RF-energy more evenly, as specified before. For larger size equipment, beyond counter-top placements, a frequency of 433 MHz could be selected to support food loads of 8 kg and more.

[0112] The dominant RF-waves may have a frequency below 1 GHz, preferably within the 902 to 928 MHz band or substantially 915 MHz, and the dominant RF-wave has a TM-mode 110. Experiments and tests of the inventor have shown that with the before mentioned parameters, the length and width of the processing chamber get in the range of 200 to 260 mm, preferably in the range of 220 to 240 mm, more preferably around 230 mm. The height of the first area during the experiments and tests was in the range of 180 mm, while the height of the holder was less than half the height of the first area. Furthermore, it was assumed that the dielectric constant of air was around 1, of the RF-permeable sides of the holder around 2 (PTFE), 3 to 4 (PEEK, fibreglass) to around 10 (ceramics) and the permittivity of the food in a very wide range from 3 to 80; while very low numbers may be for frozen food and high numbers for cold but non-frozen. As temperature increases, permittivity typically drops to around 40; this holds for mainly water-based food products, e.g. hot snack food with moist insides and crispy crust3 and of the food around 80. These dimensions are well suited for holding more substantial amounts of food, especially for commercial use.

[0113] Experiments have shown that the length and width ratio of the first area is preferably around 1. Further experiments have shown that the height versus length or width ratio of the first area is preferably around 2. Further experiments have shown that the height of the holder and thus also the food held in the holder, should not exceed 60% of the height of the first area. These limitations to be complied to for generating RF-waves inside the processing chamber with enough or considerable efficiency.

[0114] FIG. 6 further shows the vertical axis V as a dot with a cross in it as the vertical axis is perpendicular to the plane of the cross-section. The apparatus may further comprise a housing defining the outer edge of the apparatus. The housing may comprise a backplane 161 defining the face of the apparatus typically facing away from the operator. The backplane is typically facing a wall. The housing may comprise a front plane 163. The front plane is opposite from the backplane and typically facing the operator. The backplane has a first backplane end 162 and a second backplane end 162′. The first backplane end, the second backplane end and the vertical axis define a triangle T.

[0115] FIG. 7 schematically shows a detail of a cross-section of a first embodiment of the apparatus according to the invention. The detail shows the RF-antenna 155′ in the top right corner of FIG. 1.

[0116] The RF-antenna may comprise a slot 178, a shielding box 175, a RF-transparent layer 176, an RF-transparent surface 177. The slot 178 is not shown in FIG. 7, but for example is shown in FIG. 8.

[0117] The RF-antenna is fed with energy or signal through an RF-cable 170. The RF-cable comprises a core 172 and a shield 171. The core typically carries the signal, while the shield shields the core from emitting RF-waves outside the RF-cable. The Rf-cable may be a coaxial cable.

[0118] The RF-antenna may be a slotted antenna or inverse antenna as shown. Other types of RF-antennas may be used for radiating the RF-energy. The RF-antenna may further comprise an RF-transparent layer 176 having an RF-transparent surface 177. The RF-transparent surface is sealing off the inside of the shielded box to prevent dirt accumulating inside the shielded box and/or for easing cleaning of the inside of the processing chamber. The RF-transparent layer preferably seamlessly connects with the inner surface of the processing chamber. The RF-transparent layer preferably is flush with the inner surface of the processing chamber. The inside of the shielded box may be seen as a protrusion of the processing chamber. The RF-transparent layer is typically of a material which easily allows the conductance of RF-waves. The RF-transparent layer is therefore having a suitable dielectric constant.

[0119] The RF-antenna couples to the slotted antenna by having the RF-cable core 172 couple to a second RF-cable feed point 174, which is an edge of the processing chamber on one side of the slot, and the RF-cable shield 171 couple to a first RF-cable feed point 173, which is another edge of the processing chamber on an opposite side of the slot. The slot has a circumference which is typically of a length λ equalling the wavelength of the dominant to be generated RF-wave.

[0120] FIG. 8 schematically shows a perspective view of a top corner of a first embodiment of the apparatus according to the invention. The RF-antenna 155, 155′ is of the typed slotted antenna. The RF-antenna comprises a slot 178, which may be bend as shown. Other slot shapes, such as straight are envisioned by the inventor.

[0121] The processing chamber 145 may comprise a top shell 146. The processing chamber may comprise a side wall 146′ and a top wall 146″. The RF-antenna may alternatively be placed in the side wall. For clarity purposes, the shielded box is left away in this Figure and therefore drawn dotted, but it should be clear to the skilled person in the art to understand that in use the shielded box is arranged to the RF-antenna for preventing RF-waves to escape from the enclosure of the processing chamber.

[0122] FIG. 9 schematically shows a detail of a cross-section of an RF-antenna of a first embodiment of the apparatus according to the invention. The RF-antenna is an example of an inverted antenna, more specifically a planar inverted antenna or PIFA. The RF-antenna comprises a conductive antenna trace 180 which meanders to shorten the overall length of the antenna. The RF-antenna further comprises a ground plane 181. The RF-cable 170, which may be a coax-cable, may comprise a core 172 and a shield 171 coupled respectively to the antenna trace 180 via the second RF-cable feed point 174, and to the ground plane 181 via the first RF-cable feed point 173.

[0123] FIG. 10A schematically shows a seventh cross-section of a processing chamber 145 of a first embodiment of the system according to the invention. With reference to earlier figures, the same reference numeral may indicate the same feature. The processing chamber comprises a bottom shell 147 and a top shell 146. The bottom shell has a bottom rim 191, and the top shell a top rim 190. The processing chamber is shown in an open position. In this embodiment the top shell can be taken away from the bottom shell. The holder 120 is shown when held by the holding means arranged in the bottom shell. Further, the holder 120′ is shown when separated from the processing chamber. The holder 120 can be moved in a direction R to the position indicated with the holder 120′.

[0124] FIG. 10B schematically shows an eighth cross-section of a processing chamber of a first embodiment of the system according to the invention. With reference to FIG. 10A, the same reference numeral may indicate the same feature. The bottom shell slides horizontally away from the top shell for separating from the top shell in a direction S.

[0125] FIG. 10C schematically shows a nineth cross-section of a processing chamber of a first embodiment of the system according to the invention. With reference to FIG. 10A, the same reference numeral may indicate the same feature. The top shell hinges with the bottom shell in this embodiment.

[0126] FIG. 11 schematically shows a cross-section of a third embodiment of the system according to the invention. With reference to earlier figures, the same reference numeral may indicate the same feature. The apparatus comprises holding means 192, 192′ arranged inside the processing chamber. The holdings means are arranged for suspending the holder 120.

[0127] FIG. 12 schematically shows a tenth cross-section of a processing chamber of a first embodiment of the system according to the invention. With reference to earlier figures, the same reference numeral may indicate the same feature. The processing chamber 145 comprises a top shell 145 and a bottom shell 146 shown in a closed position. Further, the holder 120 is at least partly arranged inside the processing chamber. The space enveloped or enclosed by the processing chamber is the interior space 193.

[0128] The term “substantially” herein, such as in “substantially all emission” or in “substantially consists”, will be understood by the person skilled in the art. The term “substantially” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective substantially may also be removed. Where applicable, the term “substantially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%. The term “comprise” includes also embodiments wherein the term “comprises” means “consists of”.

[0129] The term “functionally” will be understood by, and be clear to, a person skilled in the art. The term “substantially” as well as “functionally” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective functionally may also be removed. When used, for instance in “functionally parallel”, a skilled person will understand that the adjective “functionally” includes the term substantially as explained above. Functionally in particular is to be understood to include a configuration of features that allows these features to function as if the adjective “functionally” was not present. The term “functionally” is intended to cover variations in the feature to which it refers, and which variations are such that in the functional use of the feature, possibly in combination with other features it relates to in the invention, that combination of features is able to operate or function. For instance, if an antenna is functionally coupled or functionally connected to a communication device, received electromagnetic signals that are receives by the antenna can be used by the communication device. The word “functionally” as for instance used in “functionally parallel” is used to cover exactly parallel, but also the embodiments that are covered by the word “substantially” explained above. For instance, “functionally parallel” relates to embodiments that in operation function as if the parts are for instance parallel. This covers embodiments for which it is clear to a skilled person that it operates within its intended field of use as if it were parallel.

[0130] In the preceding specification, the invention has been described with reference to specific examples of embodiments of the invention. It will, however, be evident that various modifications and changes may be made therein without departing from the scope of the invention as outlined in the appended claims. For example, the shapes may be any type of shape suitable to achieve the desired effect. Devices functionally forming separate devices may be integrated with a single physical device.

[0131] However, other modifications, variations, and alternatives are also possible. The specifications and drawings are, accordingly, to be regarded in an illustrative rather than in a restrictive sense.

[0132] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word ‘comprising’ or ‘including’ does not exclude the presence of other elements or steps than those listed in a claim. Furthermore, the terms “a” or “an,” as used herein, are defined as one or as more than one. Also, the use of introductory phrases such as “at least one” and “one or more” in the claims should not be construed to imply that the introduction of another claim element by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim element to inventions containing only one such element, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an.” The same holds true for the use of definite articles. Unless stated otherwise, terms such as “first” and “second” are used to arbitrarily distinguish between the elements such terms describe. Thus, these terms are not necessarily intended to indicate temporal or other prioritization of such elements. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage.

EMBODIMENTS

[0133] 1. System (100) for preparing food, comprising:

[0134] an RF-impermeable layer (110);

[0135] a holder (120) for holding the food, comprising an air-permeable side (121); and

[0136] an apparatus (140) comprising:

[0137] a processing chamber (145) arranged for being RF-impermeable and preferably air-impermeable;

[0138] holding means (148, 148′) for holding the holder inside the processing chamber;

[0139] an RF-antenna (155, 155′) arranged to radiate RF-energy to the inside of the processing chamber for heating the food inside the holder;

[0140] a fan (156) for circulating the air in the processing chamber through the air-permeable side and through the holder; and

[0141] a heater (157, 157′) arranged to provide heat to the circulated air,

[0142] wherein:

[0143] the fan and the heater are arranged for air frying the food inside the holder,

[0144] the RF-impermeable layer is also air-permeable and at least in use arranged substantially parallel to the air-permeable side of the holder,

[0145] the RF-impermeable layer in use separates the processing chamber in a first area (150) susceptible to RF-energy from the RF-antenna and a second area (151) shielded off from RF-energy from the RF-antenna; and

[0146] the fan is arranged in the second area.

[0147] 2. System according to the preceding embodiment, wherein the provision of RF-energy to the food inside the holder is independent of the provision of heated air to the food inside the holder.

[0148] 3. System according to any of the preceding embodiments, wherein the air-permeable side is arranged for allowing a vertical stream of air (A) through the holder.

[0149] 4. System according to any of the preceding embodiments, wherein the air-permeable side of the holder is an air-permeable bottom side (121).

[0150] 5. System according to any of the preceding embodiments, wherein the holder comprises the RF-impermeable layer.

[0151] 6. System according to the preceding embodiment, wherein the RF-impermeable layer is a bottom-side of the holder, preferably wherein the RF-impermeable layer and the air-permeable side are integrated.

[0152] 7. System according to the preceding embodiment 5, wherein the RF-impermeable layer is a top-side of the holder.

[0153] 8. System according to any of the preceding embodiments, wherein the holding means are at least partly RF-impermeable for in use together with the RF-impermeable layer forming an RF separation in the processing chamber.

[0154] 9. System according to any of the preceding embodiments, wherein the heater is arranged in the second area.

[0155] 10. System according to the preceding embodiment, wherein the heater is at least partly RF-impermeable for in use together with the RF-impermeable layer forming an RF-separation in the processing chamber.

[0156] 11. System according to any of the preceding embodiments, comprising:

[0157] an RF-source (158) arranged for providing RF-energy to the RF-antenna;

[0158] a motor (159) for driving the fan;

[0159] a heater source for providing energy to the heater; and

[0160] a controller (160) for controlling the amount of RF-energy from the RF-source, the number of revolutions of the motor, and the amount of radiated heat from the heater, wherein the controller controls the RF-source, the motor, and the heater independently.

[0161] 12. System according to any of the preceding embodiments, wherein the holder is a food basket.

[0162] 13. System according to any of the preceding embodiments, wherein the system is combined with any of the features from the claims chapter.

LIST OF REFERENCE NUMERALS

[0163] 100 system

[0164] 110 RF-impermeable layer

[0165] 120, 120′ Holder

[0166] 121 (4) air-permeable side

[0167] 125 handle of the holder

[0168] 140 apparatus

[0169] 141 housing

[0170] 143 axle opening

[0171] 144, 144′ joining shells

[0172] 145 (5) processing chamber

[0173] 146 (31) top shell

[0174] 146′ side wall

[0175] 146″ top wall

[0176] 147 (32) bottom shell

[0177] 148, 148′ (6, 6′) holding means

[0178] 150 (10) first area

[0179] 151 (11) second area

[0180] 155, 155′ (7, 7′) RF-antenna

[0181] 156 (8) fan

[0182] 157, 157′ (9, 9′) heater

[0183] 158 (15) RF-source

[0184] 159 (16) motor

[0185] 160 (20) controller

[0186] 161 backplane

[0187] 162, 162′ inner corner processing chamber

[0188] 162″ first backplane end

[0189] 162″′ second backplane end

[0190] 163 front plane

[0191] 164 Axle

[0192] 170 RF-cable

[0193] 171 RF-cable shield

[0194] 172 RF-cable core

[0195] 173 first RF-cable feed point

[0196] 174 second RF-cable feed point

[0197] 175 shielding box

[0198] 176 RF-transparent layer

[0199] 177 RF-transparent surface

[0200] 178 Slot

[0201] 180 antenna trace

[0202] 181 ground plane

[0203] 190 top rim

[0204] 191 bottom rim

[0205] 192, 192′ holding means

[0206] 193 interior space

[0207] A air flow

[0208] H height of the first area

[0209] L length of the first area

[0210] R removal direction holder

[0211] S separation direction shells

[0212] T Triangle

[0213] V vertical axis

[0214] W width of the first area