Field of the invention

The present disclosure relates to hand held stick mixers used for preparing food or drink, and to blade assemblies for use with such hand held stick mixers. Background of the invention

Hand held stick mixers are used in both domestic and commercial kitchens to prepare food and beverages. Typically, a hand held stick mixer ("stick mixer") includes a main body, having a handle and a motor, a drive shaft housing extending downwardly (in use) from the main body, an open blade housing at the bottom of the shaft, and a blade assembly located in the blade housing.

In operation the motor, via a drive shaft which extends through the shaft housing, rotates the blade assembly at speed to cut or mix ingredients passing within the blade housing. Typically the user grasps the stick mixer by the handle with one hand, and with the other hand secures a container holding the food drink. Known stick mixers generally have radially extending blades that rotate to cut a circular disk-shaped path, or if the blades have a slight angle, a dish-shaped path. Such an arrangement is suitable for processing food drink that enters the blade housing and into the disk/dish-shape cutting path. For example, a user may position the housing in a bowl or other receptacle holding ingredients and move the stick mixer side-to-side to maximise exposure of the food drink to such a cutting path.

Traditional stick mixers have a number of disadvantages. For example, the open blade housing does allow access to the blade which can present a safety risk. Further, in operating stick mixers the rotation of the blade assembly can cause ingredients to be ejected from the mixing receptacle. Where ingredients are cold this is merely an inconvenience, however if hot ingredients are being mixed this is again a potential safety risk. Further still, many stick mixers are inefficient or incapable or adequately processing hard ingredients such as ice, nuts and the like. It would be desirable to provide a stick mixer which reduces or eliminates one or more of the above mentioned disadvantages. In addition, or in the alternative, it would be desirable to provide the public with a useful alternative to existing stick mixers and stick mixer blade assemblies. Reference to any prior art in the specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in Australia or any other jurisdiction or that this prior art could reasonably be expected to be ascertained, understood and regarded as relevant by a person skilled in the art.

Summary of the invention

In a first aspect, there is provided a blade assembly for a stick mixer, the blade assembly including: at least three blades each having a blade tip; and at least three prongs each having a prong tip, wherein on rotation of the blade assembly about an axis of rotation the blade tips define a blade tip rotation locus about the axis of rotation and the prong tips define a prong tip rotation locus about the axis of rotation, and wherein the prong tip rotation locus is closer to the axis of rotation than the blade tip rotation locus.

In another aspect, there is provided a blade assembly for a stick mixer, the blade assembly including: at least three blades each having a blade tip; and at least two prongs each having a prong tip, wherein on rotation of the blade assembly about an axis of rotation the blade tips define a blade tip rotation locus about the axis of rotation and the prong tips define a prong tip rotation locus about the axis of rotation, and wherein the prong tip rotation locus is closer to the axis of rotation than the blade tip rotation locus.

In yet another aspect, there is provided a blade assembly for a stick mixer, the blade assembly including: at least two blades each having a blade tip; and at least three prongs each having a prong tip, wherein on rotation of the blade assembly about an axis of rotation the blade tips define a blade tip rotation locus about the axis of rotation and the prong tips define a prong tip rotation locus about the axis of rotation, and wherein the prong tip rotation locus is closer to the axis of rotation than the blade tip rotation locus.

Also disclosed herein is a hand held stick mixer including: a main body; a motor located within the main body; a controller operative to activate and deactivate the motor; a drive shaft coupled to the motor; a blade housing having a mixing chamber, the blade housing defining an opening to the mixing chamber; and a blade assembly described above, wherein the blade assembly is located within the mixing chamber and coupled to the drive shaft.

In one embodiment of the hand held stick mixer, the mixer further includes a tilt sensor or tilt switch, wherein when an angle between the axis of rotation and a vertical axis of gravity is at or beyond a specified angle, the tilt sensor or switch provides an alert signal to the controller, which in turn deactivates the motor.

In one embodiment, the hand held stick mixer further includes a user interface means for enabling at least one operating parameter of the stick mixer to be selected. In this embodiment, the motor is a variable speed motor controlled by the controller, and the at least one operating parameter includes a desired speed parameter, and wherein the controller has a soft start mode, wherein in the soft start mode the controller activates the motor by gradually ramping up speed of the motor to the desired speed parameter from an initial start.

Further aspects of the present invention and further embodiments of the aspects described in the preceding paragraphs will become apparent from the following description, given by way of example and with reference to the accompanying drawings.

Brief description of the drawings

Fig. 1 is a bottom perspective view of a stick mixer according to a first embodiment;

Fig. 2 is a side view of the stick mixer of Fig. 1 ; Fig. 3 is a front view of the stick mixer of Fig. 1 ;

Fig. 4 is a bottom view of a blade assembly according to one embodiment; Fig. 5 is a side view of the blade assembly of Fig. 4;

Fig. 6 is the bottom view of Fig. 4 showing relative geometric relationships between features of the blade assembly; Fig. 7 is the side view of Fig. 5 showing relative geometric relationship between features of the blade assembly; Fig. 8 is a close up bottom perspective view of the blade housing and blade assembly of the stick mixer of Fig. 1 ;

Fig. 9 is a bottom view of the stick mixer of Fig. 1 ;

Fig. 10 is a cross-section of a stick mixer according to another embodiment; Fig. 1 1 is a exploded top perspective view of the stick mixer of Fig. 1 showing the bayonet coupling of the main body and the shaft housing;

Fig. 12 is a top view of the stick mixer of Fig. 1 ;

Fig. 13 illustrates the dial interface and information display unit of an embodiment of the stick mixer when in a turbo mode; Fig. 14 illustrates the dial interface and information display unit of Fig. 13 when in a soft start mode;

Fig. 15 illustrates the dial interface and information display unit of Fig. 13 when in a regular mode;

Fig. 16 is a flow diagram of the operation of different operating modes of the stick mixer according to one embodiment;

Fig. 17 is a functional block diagram of some functional components of the stick mixer according to the first embodiment;

Fig. 18 is a diagram illustrating the stick mixer of Fig. 1 in three different orientations relative to the vertical axis of gravity; Figs. 19A and 19B illustrate a blade assembly according to another embodiment;

Fig. 20 is a bottom perspective view of a blade housing and blade assembly according to another embodiment;

Fig. 21 is a bottom view of the blade housing and blade assembly of Fig. 20; Fig. 22 is a representation of the blade tip rotation locus and prong tip rotation locus of a blade assembly in accordance with an embodiment of the invention;

Figs. 23A and 23B illustrate a blade assembly according to another embodiment with two blades and three prongs; Figs. 24A and 24B illustrate a blade assembly according to a further embodiment with three blades and two prongs;

Figs. 25A and 25B illustrate a blade assembly according to another embodiment;

Figs. 26A and 26B illustrate a blade assembly according to another embodiment with blades having a curved leading edge; Fig. 27. illustrates a dial interface and an information display unit in accordance with another embodiment whilst in the regular mode;

Fig. 28 illustrates the dial interface and the information display unit of Fig. 27 whilst turning the dial interface to transition between a regular mode to the soft start mode;

Fig. 29 illustrates the dial interface and the information display unit of Fig. 27 when toggled to the soft start mode; and

> Fig. 30 illustrates the dial interface and the information display unit of Fig. 27 when used in the soft start mode.

Detailed description of the embodiments

Overview A hand held stick mixer 1 according to one embodiment will now be described with reference to Figs. 1 to 3 (showing external features) and Fig. 10 (being a schematic representation of internal features of a mixer according to a similar but alternative embodiment).

The stick mixer 1 has a main body 3 housing a motor 5, with a relatively narrower grip portion of the outer surface of the main body 3 forming a handle 7. An information display unit 9 is located at an upper region 12 of the main body 3, and is surrounded by a user interface means in the form of a rotatable annular dial interface 11. Additional user interface means are provided by control buttons 13. The user interface means is linked to a controller 15 of the stick mixer 1 which is operative to activate and deactivate the motor 5.

A lower region 14 of the main body 3 is releasably connected to a first end 20 of an elongate shaft housing 17, which houses a drive shaft 19 coupled to the motor 5. At the opposite second end 21 of the shaft housing 17 is an open ended blade housing 23 defining a mixing chamber 25, and having an opening 26 to the mixing chamber 25 opposite the main body 3. The mixing chamber 25 houses a rotatable blade assembly 27 coupled to the drive shaft 19.

In an alternative embodiment, the main body 3, shaft housing 17, and blade housing 23 may be formed as a single piece.

The blade assembly 27 has an axis of rotation A around which the blade assembly rotates, and a neutral plane B perpendicular to the axis of rotation A. A plurality of blades 29 (in this instance three) radially extend away from the axis of rotation A of the blade assembly 27. In the present embodiment two of the blades 29 are angled towards the opening 26 and away from the shaft housing 17 (in a first direction C) and one of the blades is angled towards the shaft housing 17 and away from the opening 26 (in a second, opposite direction D).

A plurality of prongs 31 (in this instance three) are also provided. Each prong 31 is angled towards the opening 26 (in direction C).

Parts of the stick mixer 1 will now be described in detail.

Blade assembly

The blade assembly 27 will be described with reference to Figs. 4 to 7. The blade assembly 27 has a base element 33 which has a central aperture 35. The central aperture 35 provides means to couple the drive shaft 19 to the blade assembly 27. This may be achieved by passing a tip of the shaft into the aperture 35 and welding the shaft 19 to the blade assembly 27. Alternatively the drive shaft 19 may be coupled by press fitting the shaft 19 into the aperture 35, or passing a fastener through the central assembly 35, or any other suitable means for coupling components. The axis of rotation A of the blade assembly coincides with the length of the drive shaft 19, and passes through the central aperture 35. Three blades 29 radially extend from the base element 33, with the blades 27 equiangularly positioned around the axis of rotation, at 120 degrees from each other. Each blade 29 extends from a blade root 37 (relatively proximate to the axis of rotation A) to a blade tip 39 (relatively distant from the axis of rotation A). Each blade 29 is provided with a leading edge 33 that is chisel shaped to provide a cutting edge.

Referring to Figs. 5 and 7, the three blades 27 are angled away from neutral plane B either towards or away from the opening (i.e. in either the first C or second D direction). More specifically: a first blade 45 is angled towards the opening 26 (in direction C): a second blade 47 is angled towards the opening 26 (in direction C) though at a different angle than blade 45; and a third blade 49 is angled away from the opening 26 (in direction D). As described in further detail below, the differing angles of the blades 27 provide different cutting paths for each of the blades 27.

The angle between each blade 29 and the axis of rotation A may range from 60° to 120°. In the embodiment illustrated in Figs. 4 to 7, the first blade 45 is at an angle of approximately 70°, the second blade 47 is at approximately 80°, and the third blade 49 at approximately 105°.

Three prongs 31 also protrude from the base element 33. Each prong 31 extends from a prong root 51 to a sharpened prong tip 53, and is angled towards the opening 26 (in direction D). Each prong 31 has a leading edge 55 that is chisel shaped and swept to provide a cutting edge.

The angle between each prong 31 and the axis of rotation A may range from 0° to 45°. In the illustrated embodiment in Figs. 4 to 7, each prong 31 is at an angle of 35°.

Referring to Fig. 4, the prongs 31 also extend radially from the axis of rotation Ά, with each prong 31 being evenly spaced around the axis of rotation, at 120 degrees from each other. Each prong 31 is located substantially evenly between blades 27, at approximately 60 degrees from adjacent blades 27. Features of the blade assembly 27 are described below. Embodiments of the invention extend to blade assemblies (and stick mixers) which include individual of these features and which include any non-mutually exclusive combination of these features. Iri describing the blade assembly features, various terms/relationships will be used. In respect of these descriptions the following points are noted:

• Axis of rotation A is the axis about which the blade assembly 27 rotates.

• Neutral plane B is a plane which intersects axis of rotation A at 90 degrees. In the embodiments described and illustrated the neutral plane B is substantially coincident with the base plate and the roots of the blades and prongs. Where no base plate is used and/or blade/prong roots are in different planes, the neutral plane B may be considered to be a plane passing through the root (whether of a blade or a prong) that is located furthest away from the opening/closest to the shaft and that intersects the axis of rotation at 90 degrees. · Direction C is a direction along the axis of rotation A towards (when the blade assembly is assembled with a stick mixer) the opening 26 of the blade assembly 23 housing.

• Direction D is a direction along the axis of rotation A away from (when the blade assembly is assembled with a stick mixer) the opening 26 of the blade assembly 23 housing.

Where the angle of a blade 27 or prong 31 is referred to, the referenced angle is an angle between the axis of rotation A and a straight line that passes through each of the axis of rotation A, the blade or prong root, and the blade or prong tip. The angle is measured from the portion of the axis of rotation A extending in direction C.

• Where the angular displacement of a blade tip or a prong tip is referred to, the referenced angle is an angle between the axis of rotation A and a straight line that passes through the blade or prong tip and the point at which the neutral plane B intersects the axis of rotation A at 90 degrees. The angle is measured from the portion of the axis of rotation A extending in direction C.

• Where the vertical displacement of a point on a blade or prong referred to (e.g. the vertical displacement of a blade tip of a prong tip), this refers to the normal distance between the neutral plane B and the point in direction C. I.e. for a straight line that passes through the point and intersects the neutral plane B at 90 degrees, the vertical displacement of the point is the length of a segment of that line from the neutral plane B to the point. It will be appreciated that in this sense "vertical" refers to the displacement of the point when the stick mixer is held vertically (such that the axis of rotation A coincides with an axis of gravity). For any blades angled towards the body 3 in direction D, such as blade 49, the vertical displacement from the neutral plane B in direction C will be negative.

• Where the radial displacement of point on a blade or prong is referred to (e.g. the radial displacement of a blade tip, of a prong tip or of an intermediate point along the length of the blade/prong) , this refers to the normal distance between the point and the axis of rotation A. I.e. for a straight line that passes through the point and intersects the axis of rotation A 90 degrees, the radial displacement of the point is the length of a segment of that line between the point and the axis of rotation A. · Where the length of a blade or a prong is referred to, this refers to the length of the leading edge 33, 55 joining the blade or prong root 37, 51 to the blade or prong tip 39, 53.

Loci of rotation

Fig. 22 a diagrammatic bottom view of the paths (and loci) traced by the blade and prong tips when the blade assembly 27 is rotated. On rotation each blade tip 39 traces a rotation path 503, 505, 507 having a radial displacement from the axis of rotation. These blade rotation paths collectively define a blade tip rotation locus 501 about the axis of rotation A. The extent of the blade tip rotation locus 501 is defined by the outermost blade tip path 503 (i.e. the path of the blade tip with the greatest radial displacement) and the innermost blade tip path 507 (i.e. the path of the blade tip with the least radial displacement). By averaging the radial displacement of all blade tip paths an average radius (or radial displacement) of the blade tip rotation locus is calculated.

In the illustrated diagram, each blade tip traces a different path. In alternative embodiments, however, the paths traced by one or more of the blade tips 39 may be radially coincident (i.e. all blades may have the same radial displacement) and/or the blade tips may have different vertical displacements. If all blade tip paths are radially coincident, the outermost and innermost blade tips trace the same radial path and the blade tip rotation locus is a circle.

In a similar manner, on rotation of the blade assembly 27 each prong tip 53 traces a rotation path 523, 525, 527 having a radial displacement from the axis of rotation. The prong rotation paths collectively define a prong tip rotation locus 521 about the axis of rotation A. In the present embodiment the rotation paths of the prong tips are coincident (i.e. all three prong tips have the same radial displacement) and as such the prong tip rotation locus is illustrated as a circle and has a radius (or radial displacement) equal to the radial displacement of the prong tips. In alternative embodiments, however, the prong tips may have different radial displacements to each other and trace different radial paths, and or have different vertical displacements. In the case that the prong tips have different radial displacements, the extents of the prong tip rotation locus 521 will be defined by the path of the outermost prong tip (i.e. the path of the prong tip with the greatest radial displacement) and the path of the innermost prong tip (i.e. the path of the prong tip with the least radial displacement), and the average radius (or radial displacement) of the prong tip locus will be obtained by averaging the radial displacement of all prong tip paths.

Features of the illustrated embodiment, therefore, can be described in a number of ways:

• The radial displacement of any given blade tip path is greater than the radial displacement of any given prong tip path;

• The average radial displacement of the blade tip rotation locus is greater than the average radial displacement of the prong tip rotation locus.

• The outer extent of the prong tip rotation locus 521 is closer to the axis of rotation A than the inner extent 511 of the blade tip rotation locus 501 (i.e. the greatest prong tip radial displacement is less than the least blade tip radial displacement).

• The blade tip rotation locus 501 and prong tip rotation locus 521 are disjoint/do not overlap.

This arrangement allows the prong tips 53 to cut a different path to the blade tips 39. In the, illustrated embodiment, this allows the prong tips 53 of the prongs 31 to provide additional cutting paths (to the cutting path of the blade sections 29), which may be advantageous in use, during downward movement of the mixer 1 into hard ingredients, such as ice. Vertical displacement

Referring to Fig. 7 the prong tips 53 of the prongs 31 have a vertical displacement of dl in direction C. The blade roots 37 of the blades 29 in the present embodiment are coincident with, neutral plane B, and as such have a vertical displacement equal to 0. The vertical displacement of the prong tips 53 is greater than the vertical displacement of the blade roots 37.

This relationship is such that if the stick mixer 1 is, in use, moved downwards (i.e. a generally stabbing motion) towards ingredients (including ice), the prong tips 53 of the prongs 31 contact the ingredients before the blade roots 37 of the blade 29. This allows breaking up the ingredients before it reaching the area around the blade root 37 and around the centre of the base element 33. This is advantageous, as the "cutting" power of the blade assembly 27 in the region of the centre of the base element 33 (which does not have any cutting edges) and around the blade roots 37 may be low.

Referring to Figs. 6 and 7, an intermediate portion 41 of each blade 29 is defined as the point on the blade 29 (between the blade root 37 and blade tip 39) that has a radial displacement r3 that is the same as the average radius of the prong tip rotation locus (distance r2). For each blade 29, the vertical displacement of the intermediate point 41 on each blade from neutral plane B in direction C is less than the vertical displacement of the prong tips. In some embodiments, the vertical displacement at all intermediate points 41 on all blades will be less than the vertical displacement of the prong tips of all prongs. More generally, and in the specific embodiment being considered, at a given radial displacement from the axis of the rotation A (provided the radial displacement is occupied by at least one prong), the vertical displacement (in direction C) of a point on any prong 31 at that radial displacement is greater than the vertical displacement (in direction C) of a point on any blade 29 at that radial displacement. This configuration is advantageous during downward movement of the mixer 1 (e.g. in direction C), as the ingredients will encounter the prong tips before encountering the intermediate portions 41 of the blades 29. This is advantageous as the swept leading edge 55 of the prongs 31 are orientated closer to the axis A thereby efficiently cutting ingredients approaching the blade assembly 27 in direction D. This is in contrast to the corresponding intermediate portion 41 of the blades 29 which have a leading edge 43 which is less efficient at cutting ingredients approaching in direction D.

As can also be seen, at least one blade tip 39 of the blades 29, for example the blade tip of first blade 45, has a greater vertical displacement than the vertical displacement of the prong tips 53. This assists in preventing the prong tips 53 (which are more aggressively angled towards the opening 26 in direction C) from being stabbed directly into the bottom of the receptacle being used for mixing/processing.

Blade and prong angles

In the present embodiment, the angle from the axis of rotation A of any given blade is greater than the angle of any given prong. In more general terms, the prongs 31 are angled more sharply downward (towards the opening 26) than the blades 29 to assist in crushing ice/other hard ingredients by operation of the stick mixer 1 with a stabbing motion (i.e. ingredients approaching the blade assembly 27 in direction D).

As described above, the angle of the blade 29 may range from 60° to 120° which is greater than the angle of the prong 31 which may range from 0° to 45°.

Additionally, in the illustrated embodiment the displacement angle of any given blade tip is greater than the displacement angle of any given prong tip.

Blade and prong lengths

The length of the blade 29 along the leading edge 33 is longer than the length of the prong 31 along the leading edge 55. The blade length may range from 15mm to 40mm, and the prong 31 length may range from 3mm to 15mm. In the illustrated embodiment, the blade length is approximately 25mm and the prong length is approximately 8mm.

Blade housing

The blade housing 23 will now be described with reference to Figs. 8 and 9. The blade housing 23 has a ceiling 61 with an aperture through which the drive shaft 19 either extends through, or can be accessed, and a downwardly extending castellated side wall 63 which defines the substantially cylindrical mixing chamber 25. The opening 26 is provided at the base of the cylindrical mixing chamber 25, opposite the ceiling, to provide a passage for ingredients into the chamber 25.

Towards the opening 26, the side wall 63 is castellated with alternating flanges (protrusions) 65 and recesses (cut-outs) 67. In the illustrated embodiment, the recesses 67 provide additional side passages for ingredients to enter into and escape from the chamber 25. The corresponding five flanges 65 act as a guard to prevent the blade assembly 27 from contacting the container holding the ingredients.

Bayonet coupling

The main body 3 is releasably connected to the shaft housing 17, via a bayonet coupling 71, as best illustrated in Fig. 11. The lower region 14 of the main body 3 includes an insert 73, which is received into a socket 75 at the first end 20 of the shaft housing 17.

At the insert 73, the bayonet coupling 71 includes a ramped key guide 77 and key stop 85 to define a key track 81. At the socket 75, the bayonet coupling includes a key 83 matching the corresponding key guide 77. To connect the main body 3 to the shaft housing 17, the insert 73 is received into the socket 75, and the main body 3 is rotated relative to the shaft housing 17. This allows the key 83 to be received into the key track 81, and the cooperation of the key guide 77 with the key 83 draws the insert 73 into engagement with the socket 75. The key stop 85 is provided to prevent further rotation once the insert 73 and socket 75 are in the connected position. Corresponding detents 87, 89 are provided on the insert 73 and socket 75 to retain the main body 3 and shaft housing 17 in releasable connection.

Main body

The main body 3 houses a number of components, including inputs such as the dial interface 11, control buttons 13 A, 13B and tilt switches 91. These inputs are processed by the controller 15, which in turn provides outputs to the motor 5 and information display unit 9. This relationship of components is best illustrated in the sectioned side view in Fig. 10, and the schematic circuit diagram in Fig. 17. The embodiment described in the first embodiment (that is the embodiment shown in Figs. 1 and 17) is similar to the embodiment in Fig. 10, with the exception of slight variations in inputs to achieve the soft start mode. Therefore the common features may be described with reference to Figures representing either embodiments. Motor

The electric motor 5 is housed in the main body 3 and is operatively coupled to the drive shaft 19. Between the motor 5 and the drive shaft 19 is a releasable coupling 88 which allows torque transfer from the motor 5 and the drive shaft 19. This releasable coupling 88 also allows the motor 50 in the main body 3 and the drive shaft 19 in the shaft housing 17 to be separated for storage or cleaning. An appropriate releasable coupling 88 is a sleeve coupling, which allows ease of assembly by allowing the main body 3 and shaft housing 17 to be slid together along the axis of the drive shaft 19.

A drive mechanism (not shown) may be provided along the drive train to provide appropriate reduction in gearing. Controller

The motor is actuated by a controller 15 which controls operation of the motor 5 responsive to input from the rotatable annular dial interface 1 1 and control buttons 13, as well as operational logic (e.g. signals from tilt switches 91). In response to these operating inputs, the controller may activate and deactivate the motor, and at various speeds. In one form, the controller 15 is located on a central printed circuit board (PCB), to which the buttons 13 and tilt sensors/switches 91 are mounted, and the motor 5, dial interface 11 and information display unit 9 is connected.

The controller may be linked to, or include a microprocessor, or in the form of a microcontroller with an integrated memory device to store information operating parameters from the inputs. Rotatable annular dial interface

As described previously, the main body 3 is provided with user interface means to operate the stick mixer 1. This includes a speed selector in the form of the dial interface 11 which allows a user to select a desired speed parameter relevant to operation of the motor 5, and consequently the speed of the blade assembly 27. The dial interface 1 1 is connected to a rotary encoder or trimpot, which is responsive to provide the controller 15 with information on angular displacement of the dial interface 11. This information is used to control the speed of the stick mixer 1.

Control buttons The control buttons 13 include user operable "speed"13A and "turbo" 13B buttons. By pushing and holding the speed button 13 A, the controller 15 activates the motor 15 to the desired speed parameter. When the speed button 13A is released, the controller 15 deactivates the motor 15. When the turbo button 13B is pushed and held, the controller 15 activates the motor 15 to a preset speed, independent of the desired speed parameter. Preferably, this preset speed is a maximum speed at which the stick mixer 1 may operate. In one embodiment, the preset speed is faster than the maximum speed of the desired speed parameter that may be selected using the dial interface 11. When the turbo button 13B is released, the controller 15 deactivates the motor 5.

Information display unit An information display unit 9, in the form of a liquid crystal display is provided to visually illustrate the selected speed setting, operating mode, or other information on operating parameters. As illustrated in Fig. 12, the information display unit 9 is surrounded by the dial interface 11.

Operating modes - Soft start, regular, turbo The controller 15 in conjunction with the operating inputs, dial interface 1 1 and control buttons 13, provide the stick mixer 1 with three main operating modes: Soft start, regular, and turbo modes. These will be described with reference to Figs. 13 to 15 and the flow diagram in Fig. 16. Regular mode

In regular mode 120, when a user activates control 13A the controller 15 activates the motor 5 so as to reach the desired speed parameter as quickly as possible. The control logic 100 in the normal ("regular") mode will now be described. The stick mixer 1 is first turned on and initialised 101. The user may optionally select or change a desired speed parameter 103 by rotating the dial interface 11, and observing the information display unit 9 which visually represents the desired speed parameter, as illustrated in Fig. 15. The desired speed parameter, in this case "6", is visually represented by a digital number 201 as well as six "bars" 203 in a continuous clockwise arc starting from the "12 o'clock" position 205 of the information display unit 9. Rotation of the dial interface 11 clockwise (as indicated by the arrow in Fig. 15) increases the desired speed parameter, and conversely rotation anti-clockwise decreases the desired speed parameter.

The user may also select one of two operating modes 105 - either "regular" or "soft start". Selection of the regular operating mode 120 is achieved by rotating the dial interface 1 1 clockwise so the bars 203 extend clockwise from the "12 o'clock" position 205 of the information display unit 9 as shown in Fig. 15. To select the "soft start" mode, the dial interface 11 is rotated anti-clockwise so the bars 207 extend anti-clockwise from the "12 o'clock" position 205 as shown in Fig. 14.

The above selection steps 103 and 105 may be optional, and the stick mixer may be initiated from the start 101 with a default desired speed parameter or operating mode. Alternatively, the controller 15 may retain information regarding the last used desired speed parameter and/or operating modes.

The stick mixer 1 is now ready 106 to operate in the regular mode 120. To operate the stick mixer 1 at the now selected desired speed parameter, the user pushes and holds 107 speed button 13 A. The controller 15 will activate the motor 5 to operate at the desired speed parameter as soon as possible.

Whilst the motor 5 is activated, the user may choose to adjust the desired speed parameter by rotating the dial interface 11 to define a new desired speed parameter 122. The controller 15 in response will adjust the motor speed to this new desired speed parameter. To stop the stick mixer 1, the user simply releases 124 the speed button 13 A, and the controller 15 in turn deactivates 140 the motor 5.

Soft start mode

As described above, in the present embodiment selection 105 of the soft start mode is achieved by rotating the dial interface 1 1 anti-clockwise so the bars 207 extend in an anticlockwise arc from the 12 o'clock position 205. Furthermore a visual indicia 209 indicates the stick mixer 1 is in the soft start mode 1 10. The desired speed parameter, is increased by rotating the dial interface 11 anti-clockwise and is represented by both the bars 208 and the digital number 201. To operate this soft start mode 110, the user pushes and holds 108 speed button 13A.

The controller 15 in turn activates the motor 5 by gradually ramping up speed of the motor to the desired speed parameter. To stop 140 the stick mixer 1, the speed button 13A is released 1 14.

As in the regular mode, whilst the motor 5 is activated the user may choose to adjust the desired speed parameter 112 by rotating the dial interface 11. The controller 15 in response will adjust the motor speed to this new desired speed parameter. In one embodiment, the controller gradually increases and/or decreases the speed of the motor 5 to the new desired speed parameter.

By gradually changing the speed of the motor 5, the ingredients are mixed with gradual changes in invigoration, which reduces the likelihood of ejection or spillage of the ingredients from the container. This is especially useful to dampen acceleration or deceleration where there is a relatively large difference between the desired speed parameter and the actual speed of the motor 5.

Turbo mode

A turbo mode 130 is provided for operating the stick mixer 1 at preset speed(s) that is/are independent of the selected desired speed parameter 103. Preferably the preset speed in the turbo mode is at a relatively high operating speed of the stick mixer. In one embodiment it is equivalent to the maximum speed of the desired speed parameter that may be selected in the regular or soft start modes 103. In another embodiment, it may be faster than the maximum speed of the desired speed parameter that may be selected 103, for example at a speed of 1 10% of the maximum selectable desired speed parameter. In yet another embodiment, the turbo mode may be less than the maximum selectable desired speed parameter 103.

Activating the stick mixer 1 in turbo mode 130 is independent of the mode selection 105 or speed selection 103 of the stick mixer. To operate the stick mixer 1 in turbo mode 130, the user pushes and holds the turbo button 13B. In response, the controller 15 operates the motor 5 at the preset speed in turbo mode 130. As illustrated in Fig. 13, the information display unit 9 shows a digital "T" 211 to provide a visual indicia that the stick mixer 1 is operating in the turbo mode 130. Furthermore, there are bars 213 around the perimeter of the information display unit 9 to illustrate the stick mixer 1 is operating at a high speed. To stop (deactivate) the motor 140, the user simply releases 134 the turbo button 13B.

Advantageously, the turbo mode allows the user to quickly invigorate the ingredients at high speed without having to rotate adjust the dial interface 11.

Tilt sensor/switch The hand held stick mixer 1 is further provided with at least one tilt sensor or tilt switch

91. Suitable tilt sensor 91 may include microelectromechanical systems (MEMS) motion sensors (for example L3G4200D gyroscope offered by STMicroelectronics NV, Switzerland). A gyroscope and/or accelerometers can provide signals to the controller 15 to determine angular movement and/or orientation of the mixer 1. Alternatively a tilt switch may include an electro- mechanical switch such as the ball-rolling tilt switch 806 series offered by Light Country Co., Ltd, Taiwan. The tilt sensor or switch 91 operates to provide a signal to the controller 15 when the orientation of the stick mixer 1 between the axis of rotation and a vertical axis of gravity is at or beyond a specified angle, as illustrated in Fig. 18. If this angular value is reached or surpassed, the controller 15 is operative to deactivate the motor 5. Alternatively, the tilt switch 91 may be connected to a relay switch that disconnects at least part of an electrical circuit of the hand held stick mixer 1 to deactivate the motor 5.

The deactivation of the motor 5 may be temporary, and the controller 15 may activate the motor 5 once the angle is within the specified angle. Alternatively, the controller 15 may deactivate the stick mixer 1 until the stick mixer is "reset", either by using the control buttons 13 or by switching power off and on to the stick mixer 1.

In one advantageous embodiment, the specified angle is at +/- 90 degrees from the normal vertical operating orientation of the stick mixer 1. However, it is to be appreciated other values may be used, such as +/-45° +/-60 ⁰ , +/-70 ⁰ , +/-80 ⁰ , +/-1 10°.

Advantageously, this provides a safety mechanism to prevent inadvertent activation of the stick mixer 1 when the stick mixer is not in use, such as during washing/cleaning, or when lying on a bench top.

The tilt sensor 91 and/or controller 15 may be provided with a delay means to prevent deactivation of the motor 5 in instances where the tilt sensor 91 detects values past the specified angle, but only for a short duration. This may occur due to vibration and shaking of the unit. For example, a user may be mixing ingredients in a bowl with vigorous motion, and the motion causes the tilt sensor 91 to detect an orientation at or beyond the specified angle momentarily or for short periods. In such cases, it would be desirable that the motor 5 runs continuously so that mixing is not interrupted.

In one form, this may be achieved by including a time delay in either the tilt sensor 91 and/or the controller 15 so that deactivation of the motor 5 would only occur if an orientation at or beyond the specified angle has been detected for (or over) a specified period. In one embodiment, the specified period includes a continuous two second period. It is to be appreciated that other time periods may be used, such as one half of a second, one second, three seconds, etc.

In one form, the tilt sensor 91 provides a signal to the controller 15 that the orientation is at or beyond the specified angle only after the specified period has occurred, and in turn the signal is used to deactivate the motor 5 (either by controller 15 or a relay in the electrical circuit). That is, the time delay before deactivation of the motor 5 is built into the tilt sensor 91.

In an alternative embodiment, the tilt sensor 91 provides a 'tilt' signal to the controller 15 whenever the orientation is at or beyond the specified angle and an 'upright' signal when the orientation is less than the specified angle. On receiving the 'tilt' signal the controller 15, in turn, starts a counter/timer. If a time on the counter/timer reaches the specified period before an 'upright' signal is received, the controller 15 deactivates the motor 5. That is, the time delay is part of the control logic of the controller.

It will be appreciated that in another embodiment the 'tilt' signal may be a continuous signal to the controller when the orientation is at or beyond a specified signal. In this embodiment, the controller 15 would deactivate the motor 5 if it determines the continuous signal is received for more than the specified period.

It will be appreciated other methods of achieving this time delay may be possible.

Advantages

The above mentioned stick mixer 1 has a number of advantages as described above. In one embodiment, the secondary prongs provide additional "cutting" or "breaking" surfaces to the blade assembly for processing ingredients. This may be advantageous when using the stick mixer in a "stabbing motion", and is particularly useful for breaking up ice or other hard ingredients.

Another advantage of an embodiment of the above disclosed stick mixer 1 is the "soft start" which gradually changes the speed of the stick mixer 1 to prevent or reduce splashing of the ingredients from the container.

One advantage of the stick mixer 1 is the dial interface 11 which allows fast selection of a desired speed parameter. The dial interface 1 1, also allows selection of operating modes, which in one embodiment allows the stick mixer 1 to have simpler controls by reducing the need for a further control button.

Yet another advantage of the stick mixer 1 described above it the safety feature of deactivating the stick mixer at certain orientations. This prevents inadvertent activation of the stick mixer 1 and may prevent injuries.

Variations It is to be appreciated the blade assembly 27 may include of other configurations. For example Fig. 19 is an alternative embodiment of the blade assembly 327 with the blades 329 and prongs 331, which when installed into the blade housing 23 are angled outwardly towards the first direction C.

A further embodiment is illustrated in Figs. 25A and 25B, where the blades 829 are extensions from the base element 833, and which lie on a substantially flat common plane. Three prongs 731 are also provided, so that when installed, the prongs 731 are angled outwardly towards the first direction C.

Yet another embodiment is illustrated in Figs. 26A and 26B, with three blades 929 and three prongs 931 extending from the base element 933. The blades 929 have a curved leading edge 943. This arrangement is advantageous as the curved leading edge 943 can assist in slicing of the ingredients more efficiently. This may assist to increase longevity of the stick mixer, since less load is required to achieve the same result. Thus such a blade arrangement may prolong the life of the motor.

By way of further alternative, blade assemblies 27 in accordance with the principles of the present invention may include fewer or more than the three blades illustrated (e.g. 2 blades, 4 blades, etc) and/or fewer or more than the three prongs illustrate (e.g. 1 prong, 2 prongs, 4 prongs etc). Further, the number of blades may differ to the number of prongs.

For example, Figs. 23A and 23B illustrates an embodiment of the blade assembly 627 with two blades 629 and three prongs 631 extending from the base element 633. In another embodiment of the blade assembly 727 illustrated in Figs. 24A and 24B, there are three blades 729 and two prongs 731 extending from the base element 733.

Furthermore, it is to be appreciated the blade housing 23 may be in different forms. Fig. 10 illustrates a blade housing 323 in one alternative form. Another alternative blade housing 423 is shown in Figs. 20 to 21. This blade housing 423 has the addition of radially inward facing bluffs 493 extending into the mixing chamber 425. These bluffs 493 project or are integrally formed with the downwardly extending side wall 463. These bluffs 493 may assist in creating turbulence in the mixing chamber 425 to decrease the "suction effect" in the mixing chamber. The bluffs 493 may also guide foodstuff and ingredients towards the blade assembly 427 to assist in processing of the ingredients. In the embodiment described above and illustrated in Figs. 13 to 15, selection of "regular" and "soft start" mode is achieved by rotating the dial interface 1 1 so that the direction in which the bars 203 and 207 extend (either clockwise or anti-clockwise) to represent selection of the different modes. In an alternative embodiment, as shown in Figs. 27 to 30, selection of "regular" and "soft start" modes is achieved using the dial interface 101 1 to toggle between these · modes. Fig.27 shows a stick mixer 1 operating in the "regular" mode with bars 1203, representing speed, extending clockwise from the 12 o'clock position. The information display 1209. also shows a digital number 1201 of the speed setting. If the "soft start" is desired, the dial interface 1011 is rotated anti-clockwise as shown in Fig. 28, until the dial interface is at or passes the 12 o'clock position as shown in Fig. 29. When the dial interface 1011 is at the 12 o'clock position, the operating mode is toggled. As shown in Fig. 29, once the operating mode is toggled, this change is represented by visual indicia 1209, so that the user is alerted to this mode of operation (which in this case is the "soft start" mode). The user then selects the desired speed parameter by rotating the dial interface 101 1 clockwise as shown in Fig. 30, with the speed setting shown by the bars 1203 and digital number 1201. If the "regular" mode is desired, the user can turn the dial interface 1011 back to the 12 o'clock position to toggle the operating mode back to the "regular mode".

In the above described embodiments, the dial interface 11 was used to select between regular and soft start operating modes. However, it is to be appreciated in other embodiments that selection of operating modes may be achieved by other types of user interface, such as by an additional button 13C illustrated in Fig. 10, toggle switch etc.

In other variations the stick mixer 1 may have less or more operating modes than in the embodiments described above. In one embodiment, the stick mixer 1 has two operating modes, being the "soft start" and "turbo" modes. In this variation the stick mixer has a soft start speed button 13 A and a turbo button 13B. When speed button 13A is depressed, the stick mixer gradually increases speed to operate at the speed parameter as selected with the dial interface (i.e. the "soft start" mode). When the turbo button 13B is depressed, the stick mixer operates in the "turbo" mode as described above.

It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.