Abstract:
The disclosed method for making a milkshake or smoothie includes the steps of providing a cup containing a block of ingredients, grinding the block, and adding a liquid heated to at least approximately 100° F. The ingredients in the cup are provided in the form of a block frozen to substantially conform to the interior of the cup. In one embodiment, the method includes the step of whipping to incorporate air into a mixture of the heated liquid and the ground frozen substance in the cup. In that case, the incorporated air, heated liquid, and ground frozen substance form a milkshake or smoothie which has a total volume that exceeds the volume of the mixture of the heated liquid and block of frozen ingredients alone.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation of U.S. Pat. No. 08/866,548, filed on May 30, 1997, for “Apparatus and Method for Making Frozen Drinks” by James J. Farrell now U.S. Pat. No. 6,326,047. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to the field of food processing methods and equipment, and particularly to apparatuses and methods for making milkshakes and other frozen drinks. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to an improved means of making milkshakes and other frozen drinks. Currently the two commercially prevalent methods of making milkshakes and other frozen drinks are: 1) placing frozen ingredients such as ice cream scoops or ice or frozen fruit into a blending/mixing receptacle, then adding cool liquid such as milk or juice or water, and then blending them together, or 2) using a dispensing freezer of the type in which liquid ingredients are automatically fed into a freezing cylinder, agitated by a dasher in the cylinder during the freezing operation, and then dispensed when desired through a front discharge valve. 
     The first method, while delivering an excellent quality milkshake or frozen drink, takes too much time and labor to be viable in high volume fast-food restaurants, where a major portion of the potential market lies. The second method, using a dispensing freezer, dominates the fast-food market, yet possesses several serious short-comings. The required dispensing freezer equipment is expensive to purchase, and very time consuming and expensive to clean and maintain. In addition, the quality of product this equipment produces, by its nature, does not recreate the “old fashioned” style texture that can only be achieved by blending frozen ingredients together with liquid ingredients and then serving immediately. Consumers do not respond nearly as favorably to the homogeneous texture produced by the dispensing freezer equipment as they do to the old fashioned texture, and therefore, these dispensing freezer drinks do not sell well, holding less than 3% market share of total restaurant beverage sales today. 
     The overall goal of this invention is to enable the creation of a consumer preferred old fashioned texture milkshake or other frozen drink that will fit into the operational constraints of today&#39;s high volume fast-food restaurants. In order to meet the operational constraints of today&#39;s fast-food restaurants this invention was developed to achieve several objectives. 
     One objective is to create a milkshake or other frozen drink in 30 seconds or less. In the fast-food market literally every second of preparation time is critical. By enabling preparation time to be reduced by even a few seconds, a number of features of this invention are significant improvements over the existing art. 
     Another object of the present invention is to achieve high levels of whipping/aeration of the frozen drink, and preferably whipping/aeration of at least 15% of total volume. This level of whipping is important for two reasons. First, it is critical to keeping ingredient costs of this new method in competitive alignment with milkshakes and frozen drinks produced by dispensing freezers, which are whipped to this level of aeration and higher. Second, whipping also substantially improves flavor delivery of a frozen drink by improving a consumer&#39;s ability to taste the drink as their sense of smell senses the frozen drink&#39;s aroma trapped inside the tiny bubbles created by the whipping process. 
     In Applicant&#39;s U.S. Pat. No. 5,962,060, the disclosure of which is incorporated herein by reference, a method for making frozen drinks is described which meets the listed objectives. The application describes a method and apparatus which allows milkshakes and other frozen drinks to be quickly made by breaking up frozen blocks of ingredients into small frozen particles, and combining them with an added liquid. The ingredients to be frozen into frozen blocks are pre-mixed in liquid form, placed into serving cups which are the same serving cups in which the finished milkshake or frozen drinks are to be served, and then frozen into blocks conforming to the insides of the serving cups and stored. 
     According to the disclosure, when a milkshake or other frozen drink is to be made, a serving cup containing the frozen block is positioned in the machine. A rotating blade is lowered into the cup and bores through the frozen substance in the cup. Milk or another liquid is added to the cup for blending with the frozen substance, which is broken up into small frozen particles by the boring blade. The machine introduces air into the liquid or the liquid plus frozen particle mixture in order to give the milkshake or frozen drink its proper volume, texture, and flavor delivery. 
     For certain applications, it may be desirable to use water or another non-dairy liquid in the frozen drink making process just described. It has been found, however that when a non-dairy liquid is used as the added liquid in the process, a frozen beverage having a diluted, watery taste and granular consistency generally results. 
     Given the desirability of frozen drinks having a full-bodied flavor and a very smooth, “old-fashioned style” consistency, the present invention is directed to achieving full-bodied flavor delivery from the frozen ingredients used, and eliminating the granular consistency which may result when non-dairy liquids are used in the frozen drink process. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is a method for making frozen drinks from a block of frozen substance, and an apparatus which may be used in carrying out the method. According to the method of the present invention, a block of frozen substance is held in a vessel while a blade having features for grinding the frozen substance acts on the block, grinding the frozen substance while a heated liquid is simultaneously introduced into the vessel. An apparatus according to the present invention supports a cup containing the frozen substance, and includes a rotatable blade which is lowered into the cup and means for pumping a heated liquid into the cup. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic representation of the method according to the present invention as carried out using a blender. 
     FIG. 2 is a perspective view of a milkshake cup according to the present invention. 
     FIG. 3 is a front elevation view of a frozen drink machine according to the present invention, in which a front panel is removed to expose the carriage and blade drive assemblies. 
     FIG. 4 is a side elevation view of the frozen drink machine of FIG.  3 . 
     FIG. 5 is a front elevation view of the frozen drink machine of FIG. 3 in which the blending assembly housing has been pivoted to an open condition to expose the interior of the refrigerator housing and to further expose the back side of the blending assembly housing. 
     FIG. 6A is a front elevation view of a portion of the carriage, the sleeve mounted to the carriage, and the blade shaft extending through the sleeve and the carriage. The sleeve and carriage are cut away to more clearly illustrate the structure of the shaft and the contents of the sleeve. 
     FIG. 6B is a front elevation view, similar to the view of FIG. 6A, in which the spring is in a compressed state. 
     FIG. 7A is a front elevation view of the frozen drink machine of FIG. 3 showing the carriage at the end of its downward travel and showing the blade moving downwardly within the serving cup. 
     FIG. 7B is a front elevation view of the frozen drink machine of FIG. 3 showing the carriage and the blade at the ends of their respective downward travels. 
     FIG. 8 is a perspective view of the cup housing according to the present invention. 
     FIGS. 9A and 9B are side views of the cup housing of the frozen drink machine of FIG. 3, showing small and large cups, respectively, positioned in the cup housing. 
     FIG. 10 is a front elevation view, similar to the view of FIG. 3, in which the cup support assembly is pivoted into the opened condition. 
     FIGS. 11A and 11B are a top plan view and a side elevation view, respectively, of a blade according to the present invention. 
     FIG. 12 is a cross-sectional side view of the blade of FIGS. 11 A and  11  B, taken along the plane designated 12—12 in FIG. 11 A. 
     FIG. 13 is a simplified flow diagram showing the functions of the microprocessor of the present invention. 
    
    
     DETAILED DESCRIPTION 
     Generally speaking, the method of making milkshakes and frozen drinks according to the present invention allows milkshakes and other frozen drinks to be quickly made by breaking up frozen blocks of ingredients into small frozen particles, and combining them with an added heated liquid. The ingredients to be frozen into frozen blocks are pre-mixed in liquid form, and then frozen into blocks and stored. The ingredients may be frozen into single-serving blocks which may be removed from the freezer as needed for making individual frozen drinks. Alternatively, the ingredients may be frozen into serving cups which are the same serving cups in which the finished milkshake or frozen drinks are to be served. 
     During the frozen drink making process, the frozen block is acted upon by a rotating blade, which grinds the frozen substance into small frozen particles. Heated liquid is added to the frozen block for blending with the frozen particles. The blade may also introduce air into the liquid or the liquid plus frozen particle mixture in order to improve the milkshake or frozen drink&#39;s volume, texture, and flavor delivery. 
     For the rest of this detailed description, the details of the invention will be provided with milkshakes as the end-product being produced, though it is to be understood that end-products such as smoothies or a variety of other frozen drinks can be made by the machine and method described herein. 
     In its simplest form, the method of the present invention may be carried out using a conventional blender, which, like blender  300  of FIG. 1, includes a blending chamber  302  and a rotatable blade  304 . 
     First, ice cream mix is combined with concentrated milk; that is, milk with a portion of its water content evaporated. A preferred mixture includes typical ice cream mix as specified in the following chart, combined with milk which has been concentrated to one half its beginning weight through evaporation as also specified, resulting in the combined product as specified. 
     
       
         
               
             
               
               
               
               
             
               
               
               
               
             
           
               
                   
               
               
                 Sample Formula Specification Table 
               
             
          
           
               
                   
                 Ice Cream Mix + 
                 Concentrated Milk = 
                 Combined Product 
               
               
                   
                   
               
             
          
           
               
                 Weighted Ounces 
                 7 
                 3 
                 10 
               
               
                 Percentages by Weight: 
               
               
                 Milk Fat 
                 10.0% 
                 7.0% 
                 9.1% 
               
               
                 Non-Fat Milk Solids 
                 12.0% 
                 17.0% 
                 13.5% 
               
               
                 Sugar 
                 15.0% 
                 0.0% 
                 10.5% 
               
               
                 Emulsifiers and Stabilizers 
                 0.3% 
                 0.0% 
                 0.2% 
               
               
                 Water 
                 62.7% 
                 76.0% 
                 66.7% 
               
               
                 TOTAL 
                 100.0% 
                 100.0% 
                 100.0% 
               
               
                   
               
             
          
         
       
     
     This mixture is then frozen into an ice cream like frozen substance by incorporating air as it is agitated and frozen, such that the finished product is approximately 35% air by volume. Naturally, the ingredients and quantities may vary without departing from the scope of the present invention. Preferably, the mixture is frozen into single serving quantities of 13 fluid ounces for a 16 fluid ounce milkshake. 
     Referring to FIG. 1, when a milkshake is to be made, a scoop or block  306  of this ice cream like frozen substance is positioned in the blending chamber  302 . A measured quantity of heated water is added to the blending chamber. The blender is switched to the “on” condition to begin rotation of the blade  304 . The rotating blade  304  grinds through the frozen substance in the cup and blends the added heated water with the frozen substance as it is broken up into small frozen particles by the blade. 
     If unheated tap water were added rather than heated water, even if the milk portion of the frozen ingredients had been more greatly concentrated to compensate for the greater quantity of unheated tap water to be added, the amount of added water necessary to achieve the proper thickness of milkshake would cause the milkshake to have a watery taste. Moreover, a portion of the added unheated tap water would freeze into small ice granules during blending, causing the resulting milkshake to lack the smooth texture that is most desirable for milkshakes. 
     It has been found that this phenomenon can be eliminated if the water is heated before it is introduced into the blending chamber  302 . By heating the water, three improvements are achieved simultaneously. First, the amount of water necessary to achieve the proper thickness of finished frozen beverage is greatly reduced. For instance, to achieve the proper thickness of finished frozen beverage, a 13 fluid ounce frozen block of ice cream like frozen substance requires the addition of 6 fluid ounces of water at the typical 50° F. achieved by using ambient tap water, but only 3 fluid ounces of water heated to 170° F.. This reduction in quantity of added water impacts the watery taste problem because approximately half as much water is added, directly resulting in a less watery, more full-bodied taste. Second, as the hot water is cooled from its elevated temperature by the frozen substance during mixing, the hot water proportionally causes more of the frozen substance to be melted and incorporated into the added water, resulting in a greater concentration of the ingredients from the frozen substance being mixed into the liquid phase of the frozen beverage. The liquid phase of a frozen beverage has a much greater impact on taste than the frozen phase because it is able to be sensed by the taste buds more readily. Thus, this higher concentration of frozen ingredients melted into the liquid phase also helps very substantially to solve the watery taste problem. Third, because of the greater concentration of frozen ingredients melted into the liquid phase of the frozen beverage, the freezing point of the liquid phases is depressed further by the use of heated water. The temperature of the liquid in a finished milkshake is typically 29° F.. This is due to its concentration of sugars, which depress the freezing point from 32° F. for pure water. When typical 50° F. tap water is used, the concentration of sugars combining with the water in the liquid phase are insufficient to depress the freezing point of the added water to the 29 ° F. level, and the frozen ingredients cause a portion of the added water to freeze into small crystals. This freezing causes a granular texture. When heated water is used, the concentration of sugars in the liquid phase reaches a level adequate to depress the freezing point of the liquid phase to a level where any appreciable freezing of the water from the liquid phase into ice crystals is eliminated. This eliminates the granular texture problem. 
     An alternative embodiment of an apparatus for use in carrying out the method of the present invention is shown in FIGS. 3 through 13. While a blender works well at carrying out the method, the apparatus of FIGS. 3 through 13 is more appropriate for commercial food service in that it eliminates much of the time and labor needed using the blender method. In addition, it has the added advantage of being able to incorporate air into the frozen beverage during the mixing process. This ability to incorporate air allows the use of a frozen block of ingredients which is not pre-aerated, further simplifying the preparation of the frozen ingredients. 
     Cup and Ingredients 
     A serving cup  200  of the type which maybe used in the method and apparatus according to the present invention is shown in FIG.  2 . The exterior surface of the cup  200  includes a plurality of ridges  202 . 
     When ready for use in the machine according to the present invention, the cup  200  contains milkshake ingredients which are frozen into a block  204  which conforms to the shape of the cup. The block  204  includes an upper surface  206 . The frozen substance preferably comprises all the ingredients required to make a milkshake, with the exception of the air and a portion of the water. The Sample Formula Specification Table above lists preferred quantities for ingredients, with the exception of the air. Air is an important ingredient in a finished milkshake because it gives the milkshake its proper volume and texture, and improves flavor delivery. Specifically, a cup which will yield a sixteen fluid ounce volume milkshake typically contains a frozen block  204  of approximately ten fluid ounces of combined product, but with no air incorporated. This ten ounces of combined product consists of seven ounces of standard ice cream mix combined with six ounces of milk, as would be used in a conventional old-fashioned milkshake, except that the six ounces of milk has been reduced to three ounces of concentrated milk by evaporating out three ounces of water. This three ounces of water which has been evaporated out will be added back into the milkshake mixture later as the heated water during mixing in the frozen drink machine  10 . It should be pointed out that this approach differs from placing ice cream or an ice cream like frozen substance, as used in the earlier conventional blender example, in the cup because they, by definition, contain air which is incorporated during freezing. For instance, the ice cream typically used in old-fashioned scooped type milkshakes-typically contains approximately 35%-50% air by volume. At the completion of the milkshake making operation, the ten fluid ounces of combined product will have had three fluid ounces of heated water added, for a sub-total of thirteen fluid ounces, plus three fluid ounces of air incorporated by the whipping action of the rotating blade, resulting in the desired sixteen fluid ounce, full-bodied, smooth textured finished milkshake. 
     The ingredients are frozen into the cup  200  and form a block of frozen substance that typically fills the cup by approximately 60% of its total volume. As will be appreciated below, the full volume of the cup is used to contain milkshake once the heated liquid and air are introduced into the cup during a milkshake making operation. 
     Milkshake and Frozen Drink Machine 
     Referring to FIGS. 3 and 4, the frozen drink machine  10  according to the present invention is comprised generally of a rear housing  12 , a blending assembly housing  14 , and a cup housing  16 . 
     Referring to FIG. 5, the rear housing  12  includes a compartment  18  having a shelf  20 . Above the shelf  20 , compartment  18  contains a liquid reservoir  22  for containing the liquid (preferably water) which is added to the cup during milkshake processing. The liquid may be pumped into the reservoir  22  by an external source or it may be installed in replaceable containers. Reservoir  22  may be a heated vessel similar to a conventional hot water heater or it may be configured to receive heated liquid from an external source. Water in reservoir  22  is stored at an elevated temperature well above room temperature, preferably approximately 100 ° F.-180° F. and most preferably 170° F. 
     A tube  24  extends from liquid reservoir  22  and extends through a peristaltic pump  26 . Tube  24  has an open end  27  positioned within blending assembly housing  14 . 
     Rear housing  12  includes a base portion  29  which lies below the rear compartment  18 . A block  31  (FIGS. 4 and 5) extends from the base portion  29  and supports a pair of limit switches  33   a ,  33   b.    
     A microprocessor  35  (FIG. 5) is contained within the base portion  29  of the rear housing  12 . As will be discussed in detail below, the microprocessor  35  receives information from the limit switches  33   a ,  33   b  and other sensors which monitor operation of the milkshake machine, and manages the operation of the milkshake machine. A starting switch  37  is located on the front of the rear housing  12  and is interfaced with the microprocessor  35  to deliver starting signals to the milkshake machine when triggered by a user. 
     Referring to FIG. 4, blending assembly housing  14  is hinged to the rear housing  12  so that blending assembly housing  14  can be pivoted into the open position shown in FIG. 5 in order to allow the water supply (if a replaceable source is used) to be replaced. A support frame  28  is mounted to the blending assembly housing  14 . Upper and lower support members  30  extend laterally from support frame  28 . 
     Referring to FIGS. 3 and 4, two motors are mounted to frame  28  within the housing  14 : a carriage motor  32  and a blade motor  34 . Carriage motor  32  includes a shaft  36  which spins when the motor is activated. Shaft  36  is coupled to a first pulley  38  and a belt  39  is driven by first pulley  38 . Carriage motor  32  is preferably a stepper motor capable of 1500 RPM and 140 ounce-inches of torque. 
     Blade motor  34  is preferably a one horsepower motor capable of up to 3400 revolutions per minute. It includes a rotatable shaft  40  which is coupled to a second pulley  42  such that activation of the blade motor  34  results in rotation of the second pulley  42 . A belt  43  is driven by second pulley  42 . 
     A carriage  44  is located within the housing  14 . An elongated rod  46  (FIG. 3) extends through a bore  48  in the carriage  44  and is fixed to the support members  45 . Rod  46  is secured to the blending assembly housing  14  by a number of mounting blocks  50 . The bore  48  is proportioned such that the carriage  44  can slide easily along the rod  46 , and linear bearings (not shown) are pressed into the ends of bore  48  to aid the sliding motion. 
     Referring to FIG. 3, carriage  44  includes a laterally extending member  52  having a bore  54 . A ball nut  56  is secured within the bore  54 , and a vertical screw drive  58  extends through the ball nut  56 . The screw drive  58  is mounted to the support frame  28  by a pair of mounting members  60 . 
     A third pulley  61  is attached to one end of screw drive  58 . Belt  39  is coupled to pulley  61  such that rotation of pulley  38  results in corresponding rotation of third pulley  61 . Thus, activation of carriage motor  32  results in rotation of screw drive  58 . When screw drive  58  is rotated in this manner, ball nut  56  is caused to travel vertically along the screw drive  58  and to thereby move the carriage  44  vertically upward or downward, depending on the direction in which the screw drive is rotating. 
     Carriage  44  is a substantially rectangular frame having a rectangular center opening  62 . A bore  64  extends through the upper end of the carriage  44  and into the opening  62 . A splined spindle shaft  66  is slidably disposed in the bore  64 . Splined shaft  66  extends through a bearing  68  which is mounted to the support frame  28  by a support  69 . A fourth pulley  71 , which is internally splined, is attached to the bearing  68  and belt  43  is coupled to fourth pulley  71 . Thus, rotation of second pulley  42 , such as by activation of blade motor  34 , causes resultant rotation of splined fourth pulley  71 . 
     During rotation of splined pulley  71 , the splines in splined shaft  66  and splined pulley  71  are rotationally engaged with one another such that rotation of splined pulley  71  causes rotation of splined shaft  66 . This engagement, however, does not prevent the splined shaft  66  from sliding vertically within the splined pulley  71  and bearing  68  during vertical movement of the carriage  44 . 
     Splined shaft  66  includes a smooth section  70 . A collar  72  (FIGS. 6A and 6B) surrounds and is fixed to the smooth section  70  of shaft  66 . Shaft  66  further includes a tapered section  74  and a blade  76  attached to the tapered section  74 . 
     Referring to FIG. 6A, smooth section  70  of shaft  66  extends through a sleeve  78  mounted to the carriage  44  within the opening  62  (opening  62  shown in FIG.  2 ). A shoulder  82  is formed at the top of sleeve  78 . 
     A compression spring  80  surrounds the shaft section  70  and is housed within the sleeve  78 . Spring  80  has a first end  84  which abuts the shoulder  82  and a second end  86  which abuts collar  72 . When carriage  44  advances downwardly in the direction indicated by arrow A 1 , and blade  76  reaches the surface  206  of the frozen substance  204  in the cup, spring  80  becomes compressed between shoulder  82  and collar  72  as indicated in FIG.  6 B. Gradually, shaft  66  slides downwardly, as indicated by arrow A 2  in FIG. 6B, through the sleeve  78  until spring  80  returns to its relaxed condition shown in FIG.  6 A. 
     Referring to FIGS. 7A and 7B, an optical detector  88  is mounted to the top of carriage  44 . Optical detector includes a light source  90  and a receiver  92  which detects light emitted by light source  90 . Optical detector  88  is positioned to detect whether the upper end of splined shaft  66  is extending above the carriage  44 . When the upper end of the shaft  66  extends above the carriage  44 , receiver  92  is prevented from receiving light emitted by light source  90 . When the carriage  44  is lowered and the upper end of the splined shaft  66  can be detected by the optical detector  88 , it indicates that the blade  76  has not yet reached the bottom of the serving cup  200  which contains the milkshake ingredients. 
     Optical detector  88  is electronically coupled to microprocessor  35  (FIG.  5 ). When the blade  76  reaches the bottom of the serving cup  200  during use of the milkshake machine, this information is received by the microprocessor  35  and used to control the milkshake making operation as will be discussed below. 
     Referring to FIGS. 4,  5  and  8 , support frame  28  has a lower portion  94  positioned above the cup housing  16 . Lower portion  94  includes a recessed section  96  which, when the blending assembly housing  14  is pivoted to the closed condition shown in FIG. 4, faces the portion of the rear compartment  18  which lies below shelf  20 . 
     Recessed section  96  is bounded by three side walls  98 , a top wall  100  (FIG.  5 ), and a bottom wall  102 . Openings  104   a ,  104   b  shown in FIG. 4, are formed in top and bottom walls  102 . These openings permit the blade  76  to extend into the recessed section  96  and to pass from the recessed section into the cup  200 . 
     A solenoid latch  103  having a plunger  105  (FIGS. 9A and 9B) is attached to lower portion  94  of housing  14 . The solenoid latch  103  works in a conventional manner. Plunger  105  is spring biased in the elevated condition shown in FIG.  10 . When solenoid latch  103  is energized, plunger  105  slides vertically downward to the latched position shown in FIGS. 9A and 9B. 
     Referring to FIG. 10, cup housing  16  includes a side section  106  which is hinged to the rod  46 . Cup housing is pivotable about the rod  46  between the closed position shown in FIG.  3  and the open position shown in FIG. 10. A handle  107  is provided to permit the cup housing to be easily pivoted between the closed and open positions. When the solenoid plunger  105  is in the latched position shown in FIG. 9A, it prevents the cup housing from being moved to the open position. 
     Referring to FIG. 10, cup housing  16  includes a tray  108  which is provided with a cut-out  110  for receiving a serving cup  200 . The portion  114  of the cup housing  16  above the tray is open. Cup housing  16  further includes an outer wall  112  which, when the cup housing is in the closed position, causes the cup  200  to be enclosed between the outer wall  112  and base portion  29  of rear housing  12 . Moreover, and as best shown in FIGS. 9A and 9B, when the cup housing  16  is in the closed condition, the block  31  which is attached to rear housing  12  extends into the open portion  114  of the cup housing  16 . The wall  112  and the block  31  are important because they prevent access to the cup during the processing cycle, when it would be very dangerous to disturb the cup due to the sharp blade spinning at high RPM inside the cup. 
     Referring again to FIGS. 9A and 9B, when a cup is positioned in the cup housing and the cup housing placed in the closed condition, the cup depresses at least one of the limit switches  33   a ,  33   b . A short cup  200   b , shown in FIG. 9A, will depress only lower limit switch  33   b , whereas a tall cup  200   a , shown in FIG. 9B will depress both lower and upper limit switches  33   a ,  33   b . The switches  33   a ,  33   b  provide a means by which the presence of a cup in the cup housing maybe detected. As will be described in detail below, when at least one of the switches  33   a ,  33   b  is closed, the microprocessor activates solenoid latch  103 , causing the cup housing  16  to be locked in the closed condition and generates starting signals which cause the frozen drink making cycle to begin. 
     The limit switches  33   a ,  33   b  also deliver information to the microprocessor  35  (FIG. 5) concerning the size of the cup which is positioned in the cup housing. As detailed below, this will ensure that the appropriate quantity of liquid is delivered into the cup for the size milkshake which is to be made. Also, because the surface  206  (FIG. 2) of the frozen block  204  is lower in a smaller cup than in a relatively larger cup, the microprocessor can ensure that the blade  76  is lowered to the proper height before it is caused to begin spinning. 
     Referring to the perspective view of FIG. 8, cut-out  110  includes ridges  116  around its perimeter. These ridges are designed to engage with like ridges  202  on the outside surface of the serving cup  200 . This prevents cup  200  from rotating within the cut-out  110  as the rotating blade advances through the frozen substance. 
     Blade 
     FIGS. 11A and 11B are top and side views, respectively, of blade  76 . Blade  76  is preferably a 2.5 inch diameter stainless steel blade having a circular shape and a thickness of approximately 0.080 inches. Three-eighth inch diameter holes  118   a,    118   b  and  118   c  are spaced 120° apart rotationally and at specific radiuses from the center of the blade such that as the blade makes one complete rotation, the entire surface area of the frozen substance will have been passed over by three holes. Holes  118   a  are centered 0.041 inches from the blade&#39;s center, and holes  118   b  and  118   c  are spaced 0.062 inches and 0.083 inches from the blade&#39;s center respectively. Depressed regions  120 , best shown in the cross section view of FIG. 12, are formed immediately adjacent to each of the holes, located on their trailing edge as the blade rotates. These regions are depressed by 0.080 inches. The holes and the depressed regions are arranged such that as the blade  76  is rotated and advanced into the frozen substance in the cup  200  (FIG.  2 ), the holes  118   a-c  and depressed regions  120  grate through the frozen substance much like the grating action of a cheese grater. It should be appreciated that the blade of FIG. 11A is configured such that clockwise rotation of this blade produces the desired grating effect. This arrangement also provides for easy manufacture in a stamping operation, and maintains the mechanical strength of the blade so that its outside edges are not deflected upward by the force of the frozen substance being bored through. Other arrangements with differing size or shaped holes will also work well. 
     Three waves are formed in the blade. As shown in FIGS. 11A and 12, each of the waves  122  includes a center crease  124  which is elevated above the plane of the blade and side creases  126  which lie in the plane of the blade. The creases  124  and  126  are approximately {fraction ( 1 / 2 )} inches in length and extend radially from the perimeter of the blade. A distance along the perimeter of the blade of approximately {fraction ( 1 / 2 )} inch separates each pair of side creases  126 . During high speed rotation of the blade, the waves  122  increase the whipping effect of the blade by causing an alternately high and low pressure zone at the blade&#39;s edge, creating turbulent eddies which cause a whipping effect. 
     Three pairs of cutouts  128  are formed along the perimeter of the blade  76 , spaced 120° from each other. Each pair includes a first cutout which has a depressed trailing edge  130  and a second cutout which has an elevated trailing edge  132 . During a milkshake making operation, the trailing edge  130  is depressed to act as a grating surface to bore through the frozen substance at the outermost radius of the blade. The trailing edge  132  is elevated to act as a inverted ramped surface to force milkshake downward in the cup and thereby minimize the amount of milkshake that is driven up the interior walls of the cup by centrifugal force. Moreover, by directing milkshake ingredients above the blade, which are carried to the outer edge of the blade by centrifugal force, to then be forced downward and under the blade as the rotating blade moves upward, the elevated trailing edge  132  helps prevent the blade from carrying ingredients up and out of the cup as the blade is lifted from the cup. 
     Operation 
     Operation of the frozen drink machine according to the present invention will next be described. 
     First, cup housing  16  is pivoted to the opened condition shown in FIG. 10 and a cup  200  containing the frozen substance  204  is positioned in the cutout  110 . Cup housing  16  is then pivoted to the closed position shown in FIG.  3 . 
     Next, carriage motor  32  is activated. Activation of carriage motor  32  causes rotation of carriage motor shaft  36  and pulley  38 , and through belt  39  further causes rotation of pulley  61  which is attached to the vertical screw drive shaft  58 , causing it to rotate. Counterclockwise rotation of screw drive shaft  58 , when viewed from the top, causes carriage  44  to advance vertically downward as indicated by arrow A 3  in FIG.  3 . Carriage  44  has spindle shaft  66  mounted to it such that when carriage  44  advances vertically downward, spindle shaft  66  advances downward as well, with one exception which will be explained shortly. As blade  76 , attached to the bottom of spindle shaft  66 , approaches the surface  206  of the frozen substance  204 , blade motor  34  is activated causing rotation of pulley  42 , and through belt  43 , rotation of pulley  71  which is attached to spindle shaft  66 , causing it and blade  76  to spin. Downward travel of carriage  44  continues and blade  76  makes contact with the surface  206  of the frozen substance and begins boring down through it. 
     At the time boring begins, the liquid pump  26  is activated and begins pumping heated liquid into the cup through tube  24  for mixing and whipping with the small frozen particulate being created by the boring action of the blade. Approximately three fluid ounces of liquid at an elevated temperature of approximately 100-180° F., but most preferably 170° F., is pumped into the cup over a period of approximately three to five seconds, depending on the desired consistency of the finished milkshake. The elevated temperature of the water results in a more full-bodied taste and prevents the water from forming into ice crystals as it is blended with the ingredients contained in the cup  200 , as described earlier. 
     The downward travel of the carriage  44  is generally driven at a rate faster than the blade  76  can bore through the frozen substance in the cup. This disparity in downward travel rates causes the downward travel of the spindle shaft  66 , to which the blade  76  is attached, to be slower than the downward travel of carriage  44 . This forces the spindle shaft  66  to move upward within its mountings on the carriage  44  and for spring  80  to be compressed as shown in FIG.  7 A. The carriage  44  is driven to its lowest most point of travel, as shown in FIG. 7B, and then the carriage motor  32  is deactivated. 
     The blade  76  continues to grate and blend the frozen substance  204  within the cup  200  as it moves downward in the cup, driven by the gradual relaxation of the compressed spring  80  (FIGS. 6B and 7A) acting on spindle shaft  70 . When the optical detector  88  senses that the spindle shaft has progressed all the way to the bottom of the cup as shown in FIG. 7B, the boring stage of the process is complete. 
     The reason for this spring release arrangement is to allow for a high rate of travel speed of the carriage  44  from its uppermost position at the beginning of the cycle to the bottom of its travel. This is advantageous because it allows the blade  76  to bore as quickly as the frozen substance will allow. Softer frozen substances can be bored through more quickly. Without this spring release arrangement, time would be wasted as the carriage  44  would have to be driven downward as slowly as the hardest frozen substance could be bored through in order to be sure the blade motor  34  is not stalled out by an excessive torque requirement to continue the blade&#39;s rotation. An additional advantage is that the exact rotational speed for the carriage motor  32 , driving the downward travel of the carriage during boring, becomes less critical. This simplifies the controls required for this motor. 
     Given these two advantages of the spring release, it can be appreciated that the same advantages could be accomplished through a variety of other means, including placing the spring mechanism on the screw drive shaft or its mountings rather than on the spindle shaft, or placing a slip clutch in the connection of the carriage motor to the screw drive shaft which would slip as the spindle and carriage&#39;s downward travel was caused to slow down by the resistance of the boring blade against the frozen substance. 
     With the boring stage complete, as signaled by the optical detector  88  when the blade  76  reaches the bottom of the cup, the carriage motor  32  is caused to reverse polarity and is activated to begin to move the carriage, and with it, the spindle drive shaft and blade, upward as indicated by arrow A 4  in FIG.  7 B. At this point in the process, the rotating blade  76  acts as a mixing and whipping agitator, with the important feature of being formed such that its slim cross-sectional profile does not cause excessive rotation of the entire contents of the cup. The carriage motor  32  raises the carriage, and with it, the rotating blade up through the milkshake, completing the mixing and whipping of the frozen particulate and heated liquid into a milkshake as it travels vertically through it. 
     Some formulations of milkshake benefit from a second vertical pass of the mixing/whipping blade through the milkshake, in which case the mixing blade&#39;s vertical travel is stopped one inch below the surface  210  of the milkshake  212  (labeled in FIG.  7 B), and the polarity of the carriage motor  32  is again reversed, and the blade  76  is moved back down to the bottom of the cup. Upon reaching the bottom, the polarity of the carriage motor  32  is again reversed, and the blade is moved back upward in the cup  200  to a point one inch below the surface  210  of the milkshake  212 . 
     With the mixing and whipping process complete, and the blade reaching the point one inch below the surface  210  (FIG. 7B) of the milkshake  212 , the blade motor  34  is deactivated and a braking force applied to the blade motor to slow its rotational speed. This slowing of the blade&#39;s rotational speed prevents splattering of milkshake out of the cup as the blade breaks through the surface  210  of the milkshake  212 . With the rotation slowed, the carriage moves up to a point where the blade is approximately one half inch above the surface  210  of the milkshake  212 , but still below the top lip of the cup, and stops momentarily. With the carriage stopped momentarily, the blade motor is reactivated momentarily, causing the blade to spin and fling any remaining milkshake material off the blade and back into the cup below its upper lip. After a momentary spinning of approximately one half second, the blade motor  34  is deactivated, and the carriage motor  32  is reactivated to bring the carriage and blade upward to its original position above the cup. At this point, the process is complete and the cup can be removed for serving by opening cup housing  16  and removing cup  200  from the recess  110 . 
     As shown in FIG. 3, when the carriage  44  and blade  76  are in their original positions, the blade  76  and the narrow portion  75  of shaft  70  are disposed within recessed section  96  of the housing  14 . 
     Microprocessor Control 
     The functions of the microprocessor  35  in controlling the frozen drink making operation will next be discussed with reference to FIG. 13. A frozen drink making operation is commenced at step  300  when a user presses the start button  37  (FIG.  3 ). Next, the microprocessor  35  detects whether at least one of the limit switches  33   a ,  33   b  (FIGS. 9A and 9B) is closed, which indicates the presence of a cup  200  in the cup housing  16 . If a limit switch is closed, the microprocessor  35  causes activation of the solenoid latch  103 , step  304 , such that plunger  105  moves to the latched condition shown in FIG. 9A to latch the cup housing  16 . If a limit switch is not closed, the microprocessor terminates the milkshake making procedure or it may alternatively continue monitoring the limit switches for a predetermined period of time. 
     Next, at step  306  the microprocessor  35  determines whether a tall cup  200   a  (FIG. 9B) or a short cup  200   b  (FIG. 9A) is positioned in the cup housing  16  by determining whether only one limit switch  33   b  is closed, indicating a small cup, or whether both limit switches  33   a ,  33   b  are closed, indicating a large cup. 
     At step  308 , the microprocessor retrieves certain cup size-dependent values from look up tables stored in its memory. For example, because a larger quantity of added liquid is needed for a large milkshake than for a small milkshake, one of the stored values is the length of time for which the peristaltic pump  26  will be made to pump heated liquid into the cup  200 . The other stored values include (1) those indicating the distance to be traveled, or the amount of time for travel, by the carriage  44  to position the blade  76  at the surface  206  of the frozen block  204 , which will be higher for a large cup than it will for a small cup; (2) those indicating the distance to be traveled (or the amount of time for travel) by the carriage from the surface  206  of the frozen block  204  to the bottom of the cup; (3) those indicating the distance to be traveled (or the amount of time for travel) by the carriage to lift the blade from the milkshake to a height just below the upper surface  210  (FIG. 7B) of the milkshake  212 ; and (4) those indicating the distance to be traveled (or the amount of time for travel) by the carriage to lift the blade from the milkshake to a height just above the upper surface  210  of the milkshake  212 . 
     During steps  310  through  316 , the stored values retrieved at step  308  are used to generate control signals which control the carriage motor  32 , blade motor  34 , and peristaltic pump  26 . Specifically, the microprocessor at step  310  instructs the carriage motor  32  to advance the carriage by the appropriate number of steps to position the blade  76  just above the surface  206  of the frozen block. At step  312  the microprocessor further directs the carriage motor  32  to advance the carriage  44  by the appropriate number of steps which will cause the blade  76  to move to the bottom of the cup (step  314 ). At step  316 , the microprocessor delivers control signals to cause the peristaltic pump  26  to pump heated liquid into the cup through opening  37  for the amount of time which will deliver the proper quantity of heated liquid into the cup. 
     At step  318 , the microprocessor looks to the optical sensor  88  and awaits a signal from the optical sensor indicating that the blade  76  has reached the bottom of the cup (FIG.  7 B). When the blade  76  has reached the bottom of the cup, the microprocessor instructs (steps  320 ) the carriage motor  32  to move the carriage  44  vertically upward by an amount which will position the blade  76  approximately one inch below the milkshake surface  210 . 
     Next, the microprocessor directs the blade motor  34  (step  322 ) to deactivate and thereby slows the rotation of the blade  76 . As described above, this prevents splattering of milkshake out of the cup as the blade breaks through the surface  210  of the milkshake  212 . 
     Next, at step  324 , the carriage motor  32  is caused to advance the carriage  44  such that the blade  76  is approximately one half inch above the surface  210  of the milkshake  212 , but still below the top lip of the cup  200 . With the carriage stopped momentarily, the microprocessor reactivates the blade motor  34  for approximately 0.5 seconds (step  326 ), causing the blade to spin and fling any remaining milkshake ingredients off the blade and back into the cup below its upper lip. At step  328 , which occurs after the reactivation of the blade motor  34 , the carriage motor  32  is instructed to move the carriage  44  and blade  76  into their original positions above the cup  200 . Finally, at step  330 , the microprocessor  35  causes deactivation of the solenoid latch  103 , causing plunger  105  to move to the unlatched position shown in FIG. 10, allowing the cup housing  16  to be opened by a user. 
     The present invention has been described with respect to two embodiments, one which utilizes a blender and another which utilizes a frozen drink machine. It should be appreciated, however, that many modifications may be made to the described embodiments without departing from the scope of the invention. For example, the method as described with respect to each embodiment may be carried out using a frozen substance that is pre-aerated or one that is not pre-aerated. Additionally, the method of the invention may be practiced using equipment other than that described herein. Accordingly, Applicant&#39;s invention should be limited only in terms of the appended claims and should not be restricted by the described embodiments.