SYSTEM WITH IN- SHELF LIGHTING

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of US provisional application 61/333,069 filed May 10, 2010 and hereby incorporated by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to refrigerator shelves and in particular to an adjustable refrigerator shelf providing in-shelf lighting.

BACKGROUND OF THE INVENTION

[0003] Lights in a refrigerator are typically mounted to the interior walls of the refrigerator compartment. While these lights provide sufficient illumination when the refrigerator is empty, when the shelves are filled with goods, light is blocked and portions of the shelves are cast in shadows.

[0004] One solution to this problem is placement of lighting systems on the shelves themselves, for example on the underside of the shelves to illuminate the contents of the shelf below or on the upper edges of the shelves to illuminate product on the shelf itself.

[0005] A problem with shelf-mounted lighting is getting electrical power to the lights.

Refrigerator shelves are typically adjustable in position and can be removed entirely from the refrigerator for cleaning. While releasable electrical connectors could be provided for connecting electricity to the shelves, these connectors necessarily but undesirably break the continuous inner wall of the refrigerator and expose conductors making cleaning the inner surface of the refrigerator more difficult.

[0006] One solution to this problem is described in PCT patent application WO 2009/079209 having a filing date of December 3, 2008, and entitled "Inductively Powered Light

Assembly" assigned to the assignee of the present invention and hereby incorporated by reference. The invention described in this application uses inductively coupled power transfer between a primary coil positioned behind the walls of the refrigerator and corresponding coils on the shelves. An elongated primary coil spanning multiple shelf locations may be used to provide flexibility in the arrangement of the shelves.

[0007] An improvement in this design is described in pending US application 61/314,833 filed March 17, 2010 and entitled "High-Efficiency Wireless Lighting System" which provides a series of separate, smaller coils that provide more focused electrical coupling between power coils in the walls of the refrigerator and corresponding shelf coils on the shelves. Sensing of coil proximity may be used to efficiently disable coils not being used. This application is also assigned to the assignee of the present invention and hereby incorporated by reference.

SUMMARY OF THE INVENTION

[0008] The present invention combines a wireless transmission system with a shelf bracket allowing rapid adjustment of the shelf up and down without removal of the shelf. The assembly provides an improved structure for holding the broad area wireless coils that simultaneously provides the benefits of rapid shelf adjustment. In one embodiment, the design permits the sharing of one of the transmitter or receiver coils among shelf positions reducing total cost. In one embodiment, the invention integrates wireless power-transmitting coils into a special refrigerator wall plate that permits wireless lighting to be added to a given refrigerator model simply by attaching the wall plates to the inside of the refrigerator walls at a late stage in manufacturing.

[0009] Specifically, the present invention provides a wireless illuminated refrigerator shelf assembly usable with a refrigerator and including a power-transmitting coil adapted to attach to a refrigerator wall to transmit a low frequency electromagnetic field. A shelf receivable within the refrigerator extends between refrigerator walls, and a cardioid track and pin assembly provides an interface between the shelf surface and at least one of the refrigerator walls to stably rest at two different heights on the refrigerator walls in response to successive upward or downward motions of the shelf surface. At least one power reception coil is attached to move with the shelf surface to receive a low frequency electromagnetic field from the power-transmitting coil and provide an electrical current and a set of the light emitting diodes receiving the electrical current and supported by the shelf to provide a source of illumination moving with the shelf.

[0010] It is thus a feature of at least one embodiment of the invention to exploit a synergy between the structure of the quick adjust shelf bracket and the preferred form factor of wireless transmitting coils. It is a further feature of at least one embodiment of the invention to permit rapid shelf adjustment without necessarily removing the shelf for an illuminated shelf.

[0011] The power-transmitting coil may extend between the two different heights to overlap with the power reception coil at the two different heights. [0012] It is thus a feature of at least one embodiment of the invention to provide a simple method of ensuring power transmission to the shelf at multiple positions without the need for the consumer to switch circuits or the like.

[0013] The wireless illuminated refrigerator shelf assembly may include first and second power reception coil positions to alternately align with the power-transmitting coil at the two different heights.

[0014] It is thus a feature of at least one embodiment of the invention to minimize the size and hence power loss of the power-transmitting coil.

[0015] The wireless illuminated refrigerator shelf assembly may further include a circuit switching between the two different power reception coils depending upon which power reception coil is receiving power.

[0016] It is thus a feature of at least one embodiment of the invention to further limit power loss in an unused power reception coil.

[0017] The circuit may comprise a diode array.

[0018] It is thus a feature of at least one embodiment of the invention to simplify the method of steering power from the active receiving coil.

[0019] The wireless illuminated refrigerator shelf assembly may include a first and second power-transmitting coil positioned to alternately align with the power reception coil at the two different heights.

[0020] It is thus a feature of at least one embodiment of the invention to simplify the shelf design.

[0021] The wireless illuminated refrigerator shelf assembly may further include a shelf sensor controlling power to the first and second power-transmitting coil according to whether a power reception coil is positioned nearby.

[0022] It is thus a feature of at least one embodiment of the invention to minimize power usage in unused power-transmitting coils.

[0023] The cardioid track may be affixed to a refrigerator wall and the pin assembly is attached to move with the shelf.

[0024] It is thus a feature of at least one embodiment of the invention to provide a simple assembly that can be applied to the inner surface of a refrigerator wall to house the necessary power-transmitting coil and provide for quick adjustment without extensive modification to the refrigerator walls.

[0025] The power- transmitting coil may surround a groove of the cardioid track receiving the pin. [0026] It is thus a feature of at least one embodiment of the invention to closely integrate the power-transmitting coil and the cardioid track to maximize refrigerator usable volume.

[0027] The cardioid track may alternatively be attached to move with the shelf surface and the pin is affixed to the inner wall of the refrigerator.

[0028] It is thus a feature of at least one embodiment of the invention to permit selective use of an adjustable shelf at multiple locations without substantial modification of the refrigerator walls.

[0029] Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings in which like numerals are used to designate like features.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Fig. 1 is a perspective view of a simplified refrigerator showing a shelf having quick adjustment shelf brackets on left and right edges of the shelf;

[0031] Fig. 2 is a perspective view of one shelf showing a first embodiment of the quick adjustment shelf brackets and showing cross-sectional views of alternative orientations of the light emitting diodes on each shelf;

[0032] Fig. 3 is an exploded front perspective view of the first embodiment of the quick adjustment shelf bracket showing a shelf plate receiving a pin extending inward from the refrigerator wall that may slide up and down a cardioid track of the shelf plate, the latter shown in phantom further showing placement of a small area power-transmitting coil behind the wall plate ;

[0033] Fig. 4 is a side elevational view of the shelf plate of Fig. 3 showing the cardioid track in the shelf plate for providing simple adjustment of the shelf between two heights and showing the positioning of two receiver coils on the shelf plate for alternate alignment with the power- transmitting coil;

[0034] Fig. 5 is a front perspective view of a second embodiment of the quick adjustment shelf bracket showing a wall plate (in phantom) having a traveler attached to the shelf that may slide up and down the wall plate;

[0035] Fig. 6 is a side elevational view of the wall plate of Fig. 5 showing the cardioid track in the wall plate;

[0036] Fig. 7 is an exploded perspective view of the shelf assembly of Fig. 5 showing placement of a large area power-transmitting coil behind the wall plate and a power receiving coil behind the traveler of the shelf bracket; [0037] Fig. 8 is a block diagram of the driving and receiving circuitry used with the first and second embodiment of the shelf bracket for the efficient transmission of power from the refrigerator housing to the individual shelves;

[0038] Fig. 9 is a cross-sectional view through a printed circuit board implementing a primary coil or secondary coil and showing an optional reinforcing metal form for increasing current capacity;

[0039] Fig. 10 is a simplified circuit schematic of the driving circuitry of Fig. 8;

[0040] Fig. 11 is a figure similar to that of Fig. 10 showing the receiving circuitry; and

[0041] Fig. 12 is a fragmentary view similar to that of Fig. 11 showing a combination of power from two power receiving coils.

[0042] Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of "including" and "comprising" and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] Referring now to Fig. 1, a refrigerator 10 may provide for a housing 12 having left, right, top, bottom, and rear insulated walls together defining generally an enclosed rectangular volume open at the front. A door 14 may hinge at a front edge of one side wall to provide, when closed, a refrigerated volume maintained at a desired temperature by a compressor system (not shown).

[0043] One or more horizontal, planar shelves 16 may be placed within the volume at various heights as supported by quick adjustment shelf brackets 18 on the left and right sides (only the right wall plate is shown).

[0044] Referring now to Fig. 2, the shelf 16 may include an outer frame 23, for example, constructed of an opaque thermoplastic material to hide wiring and circuitry and supporting a center transparent portion 19, for example a pane of tempered glass. The outer frame 23 on its left and right edges may support a vertically extending shelf plate 25 providing a cardioid track 26 exposed outward on the left and right surfaces to abut inner walls of the refrigerator 10 (shown in Fig. 1). The outer frame 23 may hold one or more light emitting diodes 36 positioned in the frame 23 to be directed upward to illuminate goods placed on the transparent portion 19 or downward to illuminate goods placed on a lower shelf (not shown).

[0045] The quick adjustment shelf bracket 18 provides a connection between the shelf 16 and inner walls 22 of the refrigerator 10 allowing the shelf to be raised and lowered between two different heights simply by pressure on the shelf without direct access to the quick adjustment shelf bracket 18.

[0046] Referring now to Fig. 3, the walls 22 of the refrigerator 10 may provide an outwardly extending pin 28 retained in a slide track 30 to move horizontally left and right. The pin 28 may engage the cardioid track 26 in a rear surface of the shelf plate 25 which, as will be described below, cooperates to stably hold the shelf plate 25 and hence the shelf 16 in an upper or lower position. The shelf plate 25 may be retained slidably in vertical alignment by a vertical guide mechanism, for example, outwardly extending left and right vertical tracks 34 on the shelf plate 25 engaging corresponding channels 39 positioned to the left and right of the shelf plates 25 when mounted against the walls 22. This or a variety of other mechanisms may be used to constrain the shelf plate 25 for vertical travel.

[0047] Referring still to Fig. 2, a power-transmitting coil 37 may be positioned behind the refrigerator wall 22 adjacent to the location of the shelf plate 25 to be attached to a source behind the wall 22. [0048] Referring now to Figs. 2 and 3, the cardioid track 26 may be a groove extending into the shelf plate 25 from its rear face and is generally an inverted heart-shape having two lower lobes joining to an upper vertex. The cardioid track 26 guides the pin 28 as it moves between two stable positions: a lower position (with respect to the shelf plate 25) with the pin 28 at position 46a being in a notch between the lobes of the cardioid, and an upper position with the pin at position 46b at the uppermost vertex of the cardioid track 26. The upper position of the pin 28 represents the lowest position of the shelf 16 and vice versa. Starting with the shelf plate 25 at its lower position where the pin 28 is at upper position 46b on the shelf plate 25, the cardioid track 26 is generally asymmetric so that the pin 28, starting at position 46b and moving downward with respect to the shelf plate 25 with a lifting of the shelf 16 and shelf plate 25, will follow a leftmost groove of the cardioid track 26 to a position 46c in the leftmost lobe of the cardioid track 26 where the pin 28 is trapped against further relative downward motion.

[0049] Downward motion of the shelf 16 and shelf plate 25 from position 46c requires the pin 28 to rise to position 46a where it supports the cardioid track 26 to hold the shelf 16 in a second position elevated with respect to the shelf position when the pin 28 was at position 46b where it started.

[0050] New, upward motion on the shelf 16 and shelf plate 25 causes the pin 28 to move downward relative to the shelf plate 25 to position 46d in the rightmost lobe of the cardioid track 26 where subsequent upward motion of the pin 28 from this position (by downward motion of the shelf plate 25) causes it to return to position 46b.

[0051] Thus, successive upward and downward motion on the shelf 16 (and hence shelf plate 25) by the consumer moves the shelf 16 bi-stably between upper and lower positions. As the pin 28 moves through the cardioid track, it may slide within slide track 30 slightly to accommodate left and right movement of the pin 28 necessary to follow the cardioid track 26. A cardioid track of similar design is described generally in European patent EP 1563762 filed February 16, 2005 and entitled: "Easy Height Adjustment Device for Refrigerator Shelves" and United States Patent 7,740,332 both assigned to the assignee of the present invention and hereby incorporated by reference.

[0052] Referring now to Figs. 3 and 4, the shelf plate 25 may support first and second power receiving coils 38a and 38b positioned to be alternatively in alignment with the power- transmitting coil 37 when the shelf plate 25 is in the uppermost or lowermost positions. In this way, power can be effectively transmitted to the shelf 16 in either position. [0053] In an alternative embodiment, the power-transmitting coil 37 or the one power- receiving coil 38 may extend the full height of the shelf plate 25 to permit alignment between a single pair of coils through some overlap at either shelf position.

[0054] Referring now to Fig. 5, in a second embodiment, the cardioid track 26 may be placed in a wall plate 31 attached to a wall 22 of the refrigerator (shown in Fig. 1). The wall plate 31 may generally provide vertical guide surfaces or ways that may be engaged by a traveler 21 attached to the shelf 16 so that the traveler 21 may slide up and down the wall plate 31 retained by the wall plate 31 against torsion to provide stable support for the shelf 16. The traveler 21 may include a pin 28 analogous to that described in the first embodiment held within a slide track 24 permitting limited forward and backward motion of the pin 28. The pin 28 extends into a cardioid track 26, as will be described, open on the outer surface of the wall plate 31 to follow the cardioid track 26 as traveler 21 moves up and down along the wall plate 31.

[0055] As depicted, only a shoulder portion of the wall plate 31 is shown, it being understood that this shoulder portion may be attached to a stand-off portion so that the shoulder portion is spaced from a wall of the refrigerator to permit free travel of the traveler 21 up and down the shoulder portion.

[0056] The traveler 21 may be attached to a shelf frame 23 which, in turn, holds the transparent portion 19 and LEDs 36 as before.

[0057] Referring now to Fig. 6, the cardioid track 26 may be a groove extending inwardly into the wall plate 31 from an exposed face of the wall plate 31 and, as before, generally heart-shaped albeit inverted with respect to the previous embodiment having two upper lobes joining to a lower vertex. The cardioid track 26 guides the pin 28 between two stable positions: position 46b being at the lowermost vertex of the cardioid, and position 46a being in a notch below the lobes of the cardioid. The cardioid is generally asymmetric so that the pin 28, starting at position 46b and moving upward with a lifting of the shelf 16 and frame 23, will follow a right most groove of the cardioid track 26 to a position 46c in the rightmost lobe of the cardioid where the pin 28 is trapped against further upward motion.

[0058] Downward motion of the shelf 16 and frame 23 from position 46c requires the pin 28 to drop to position 46a where it is supported by the cardioid track 26 to hold the shelf 16 in a second position elevated with respect to the shelf position when the pin 28 was at position 28 a where it started. [0059] Further, upward motion on the shelf 16 and frame 23 causes the pin 28 to move to position 46d in the leftmost lobe of the cardioid where subsequent downward motion from this position causes it to return to position 46b.

[0060] Thus, as before, successive upward and downward motion on the shelf 16 (and hence shelf frame 23 and traveler 21) by the consumer moves the shelf 16 bi-stably between upper and lower positions. As the pin 28 moves through the cardioid track, it may slide within slide track 30 slightly to accommodate frontward and backward movement of the pin 28 necessary to follow the cardioid track 26.

[0061] Referring now to Fig. 7, the wall plate 31 may be molded thermoplastic to provide a concave rear surface receiving a power-transmitting coil 37 within the wall plate 31 between the wall plate 31 and a wall 22 of the refrigerator and surrounding the cardioid track 26 and may include a cutout portion 33 allowing it to be closely positioned to the power receiving coil 38. The wall plate 31 may be mounted to the wall 22 of the refrigerator by means of one or more self-tapping screws 35 or other assembly techniques so that it may be added to refrigerator 10 with only the addition of a small hole 41 in the wall 22 for power to the circuitry of the power-transmitting coil 37. In this embodiment, the power-transmitting coil 37 may extend the full height of the wall plate 31 to provide an oscillating magnetic field that may be inductively coupled to the power-receiving coil 38 at the two positions of the shelf. The power-receiving coil 38 may be received within the traveler 21 thereby to be properly aligned with the power-transmitting coil 37 for optimum electrical transmission and coupling. Wires may connect the power-receiving coil 38 to a light bar assembly 43 holding the individual LEDs 36 within the frame 23.

[0062] In an alternative embodiment, multiple power-receiving coils 38 per the previous embodiment or multiple power- transmitting coils 37 may be used to ensure power- transmitting at either shelf location. In the latter case, the multiple power-transmitting coils 37 may each include a shelf sensor as described below.

[0063] Referring now to Fig. 9, in either embodiment, the power-transmitting coil 37 and a power-receiving coil 38 may be fabricated on a printed circuit board using traces 40 on a printed circuit board substrate 42, for example a glass epoxy substrate material. The traces 40 may be formed in a spiral pattern to eliminate cross over in a single dimension of the trace or may be concentric circles connected by vias and other layers of the circuit board or the like. The power-transmitting coil 37 may be provided with increased current capacity by soldering a metal wire form 44 (for example a copper wire) to the trace to be supported and constrained thereby. Other components (to be described below) with respect to each of the coils may be soldered on similar traces on the opposite side of the printed circuit board substrate 42 to provide a compact, robust and integrated assembly. The power-transmitting coil 37 or power-receiving coil 38 may be, for example, planar in configuration passing in a rectangular helix to form a so-called "fingerprint" coil substantially within a plane of the printed circuit board. The power-transmitting coil 37 or power-receiving coil 38 may be separated only by non-ferromagnetic thermoplastic material of the wall 22 of the refrigerator or the materials of the quick adjustment shelf bracket 18. In cases where the power- transmitting coil 37 is placed within the walls 22 of the refrigerator 10, it may fit inside of any insulating material placed around the refrigerator.

[0064] Referring now to Fig. 8, each power-transmitting coil 37 may receive an alternating current signal from an oscillator 50 synthesizing that signal from a DC source 52, for example, of twenty-four volts available in the refrigerator 10 from a conventional DC power supply of the type well known in the art. Generally, the frequency of oscillation will be substantially above that of line current (i.e. 60 Hz) or rectified line current (e.g. 120 Hz) and may be, for example, 350 to 700 kHz to provide for more efficient transmission. Such higher frequencies also permit filtering with smaller capacitors.

[0065] The output of the oscillator 50 may be provided to a resonant circuit formed by the inductance of the power-transmitting coil 37 and a capacitor 54 together tuned to a resonant frequency substantially equal to the fundamental frequency of the oscillator 50. The circuitry to produce the AC oscillator 50 can be placed on the same printed circuit board holding the power-transmitting coil 37. Higher frequency operation is further enhanced by elimination of a magnet core of ferromagnetic material permitting more efficient high-frequency operation by the elimination of eddy current losses.

[0066] The power receiving coil 38 may also be tuned to the resonant frequency of the power-transmitting coil 37, for example, by a tuning capacitor 56 to efficiently inductively couple to the power-transmitting coil 37 thereby providing an AC signal to a rectifier 58 and filter 60 to provide DC power to a regulator 62. The regulator 62 may be, for example, a boost or buck converter that may provide a controlled voltage or current to the LEDs 36 contained on each shelf 16.

[0067] When there are multiple power-receiving coils 38a and 38b a similar capacitor 56a may be used to tune the power-receiving coil 38b, and the signals from the power-receiving coils 38a and 38b may be combined by the rectifier 58 as will be described below.

[0068] The power-transmitting coil 37 may also be attached to sensing circuitry 64 sensing the presence of a shelf near the power-transmitting coil 37 by sensing the load of power receiving coil 38, for example, as a decrease in voltage on power-transmitting coil 37, and may communicate with the oscillator 50 to turn the oscillator 50 off when there is no shelf present, thus conserving power. The shelf sensor 64 may periodically turn the oscillator 50 on to check for a new shelf 16 in a place adjacent to that power- transmitting coil 37.

[0069] Referring now to Fig. 10, transmitter circuitry 66 associated with the power- transmitting coil 37 may include a bi-stable multi-vibrator 68 (for example a 555 timer) using a capacitive/resistive network and comparators to provide a substantially 50% duty cycle waveform 70 at the desired resonant frequency to a half bridge driver 72. The half bridge driver 72 may drive transistors 74a and 74b connected at a common point to power- transmitting coil 37 and have their other leads connected to power and ground respectively. For this purpose, the half bridge driver 72 may provide two modified waveforms 76 (only one shown for clarity) at 180° phase difference providing a switching of the transistors 52a and 52b alternately on and off while ensuring no overlap. The resulting switched signal may be applied to a resonant circuit formed from the power-transmitting coil 37 and capacitor 54 connected in series to ground to provide a substantially sinusoidal current flow 78 at the desired frequency. A junction between the power-transmitting coil 37 and capacitor 54 may be monitored by a threshold-detecting amplifier 80 that may activate the reset line of the oscillator 68 turning the oscillator 68 off when voltage rises beyond a certain point indicating the absence of an adjacent shelf 16 on the opposite side of the refrigerator to the inner wall 22.

[0070] Referring now to Fig. 11 , the receiving circuitry 82 may attach to the power receiving coil 38 to also provide for a parallel resonant tuned circuit by means of capacitor 56 connected across power-receiving coil 38 and providing, with the inductance of power receiving coil 38, a center resonant frequency substantially equal to the center resonant frequency of the circuit of power-transmitting coil 37. The resulting sinusoidal received waveform 84 may be rectified by a full wave rectifier 58 and filtered by a filter 60 comprising a shunting capacitor to provide unregulated direct current to the voltage regulator 62. A subsequent filter capacitor 86 may be provided to further filter the output of the regulator 62. The LEDs 36 are shown connected in parallel but alternatively may be connected in series and the series connected LEDs operated at a higher voltage.

[0071] Referring now to Fig. 12, in the event that two power-receiving coil 38a and 38b are employed their signals may be combined through the use of separate full wave rectifiers 58a and 58b, for example, connected at their output terminals. In this way, power is not lost in the power-receiving coil 38 that is not receiving power. [0072] Various features of the invention are set forth in the following claims. It should be understood that the invention is not limited in its application to the details of construction and arrangements of the components set forth herein. The invention is capable of other embodiments and of being practiced or carried out in various ways. Variations and modifications of the foregoing are within the scope of the present invention. It also being understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text and/or drawings. All of these different combinations constitute various alternative aspects of the present invention. The embodiments described herein explain the best modes known for practicing the invention and will enable others skilled in the art to utilize the invention.