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United States Patent 3,612,969
Cockroft October 12, 1971

AUTOMATIC BLENDER

Abstract

An automatic blender than can be programmed to perform a variety of tasks with perforated recipe cards is provided. The card bearing the desired recipe is inserted between a printed circuit control board and an assembly of spring brushes so that the perforations allow only selected brushes to make electrical contact with the printed circuit board. The blender START pushbutton and power switch are also actuated by the recipe card, so the blender has no external controls.


Inventors: Cockroft; James B. (Wauwatosa, WI)
Assignee: John Oster Manufacturing Co. (Milwaukee, WI)
Appl. No.: 04/837,759
Filed: June 30, 1969


Current U.S. Class: 318/123 ; 318/163; 318/443; 388/840; 388/936; 99/643
Current International Class: G05B 19/04 (20060101); G05B 19/14 (20060101); H02P 7/18 (20060101); H02P 7/295 (20060101); H02p 007/18 ()
Field of Search: 318/163,305,443 200/46 146/68R

References Cited

U.S. Patent Documents
2677285 May 1954 Volk
3070673 December 1962 Beguin
3112379 November 1963 Holzer
3217188 November 1965 Bauer
2715703 August 1955 Schuck
3383794 May 1968 Ruth
Primary Examiner: Rader; Oris L.
Assistant Examiner: Crosson; K. L.

Claims



What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A programmable blender comprising:

a blender including a motor;

a source of electrical power;

control circuitry means connecting said source of electrical power to said motor for regulating both the speed and the time of energization of said motor;

a plurality of switches within said control circuitry each including two separable contacts and oriented so that the contacts lie on opposite sides of a plane when separated;

a plurality of planar elements bearing perforations positioned to correspond to the locations of selected switches within said plane; and

means for positioning a planar element within said plane so as to separate the contacts of all but the selected switches said selected switches causing said motor to operate at a predetermined speed with a predetermined time of energization.

2. A programmable blender in accordance with claim 1 wherein the switches each comprise a spring brush contact positioned adjacent a surface contact.

3. A programmable blender in accordance with claim 2 wherein the surface contacts are clad sections of a planar-printed circuit board positioned parallel to and adjacent said plane.

4. A programmable blender in accordance with claim 2 wherein the spring brush contacts comprise a plurality of spring-temper phosphor-bronze spring wires anchored in a metal base.

5. A programmable blender in accordance with claim 1 wherein the planar elements are recipe cards bearing recipes for dishes which may be prepared with the assistance of the blender.

6. A programmable blender in accordance with claim 1 wherein the planar elements contain knockouts positioned to correspond to the location of each switch within the plane, said knockouts being easily removable to leave perforations adjacent switches which may be selected.

7. A programmable blender in accordance with claim 1 and further including a power switch connected between said source of electrical power and said control circuitry, said power switch being normally open, and said power switch being arranged to close whenever a planar element is properly positioned within said plane so as to separate the contacts of all but the selected switches.

8. A programmable blender in accordance with claim 7 wherein the power switch comprises a spring knife section positioned adjacent said plane, and a surface contact section positioned so that the spring knife section is forced against the surface contact section whenever a planar element is properly positioned within said plane.

9. A programmable blender in accordance with claim 8 wherein the surface contact section is a clad section of a printed circuit board.

10. A programmable blender in accordance with claim 1 wherein the control circuitry includes a start switch, and also timing means disconnecting said source of electrical power from said motor at a predetermined time interval after the start switch is actuated.

11. A programmable blender in accordance with claim 10 wherein the start switch is positioned in said plane so that it is actuated by an edge of a planar element whenever a planar element is positioned properly within said plane.

12. A programmable blender in accordance with claim 11 wherein the start switch comprises a switch blade that is rigidly fixed at one end and has a portion positioned so as to be shifted by an edge of a planar element whenever a planar element is placed into position within said plane, and a fixed contact that is positioned to make electrical contact with said switch blade when the blade is shifted by a planar element.

13. A programmable blender comprising:

a blender including a motor;

a source of electrical power;

control circuitry means connecting said source of electrical power to said motor for regulating both the speed and the time of energization of said motor, and having a plurality of control signal inputs;

a plurality of planar elements bearing machine-readable indicia;

insertion means for feeding one of said planar elements into the blender; and

translation means within the blender for converting the machine-readable indicia into electrical signals, and signals being fed into the control signal inputs of the control circuitry.

14. A programmable blender in accordance with claim 13 wherein the control circuitry includes means responsive to alteration of the control signals for varying the speed and the time of operation of the blender.

15. A programmable blender in accordance with claim 14 that further includes energization means responsive to the presence of a planar element within the blender for energizing the control circuitry, and also starting means responsive to the insertion of a planar element into the blender for initiating a timed operation of the blender motor.
Description



The present invention relates to a blender and more particularly to a blender that can be programmed by the insertion of programming means, such for example as a perforated card.

Automatic blenders having relatively sophisticated control circuits are widely used today to perform a large number of different tasks in the kitchen, such as crumbing, chopping, grating, grinding, pureeing, liquefying, blending, whipping and mixing. Substantially all blenders include a speed control adjustment to best adapt the device for a particular function, and some include intermittent operation controls which facilitate certain operations. Many blenders also include an automatic timer that shuts down the blender after a particular task is completed. An example of an automatic blender featuring all electronic controls is disclosed in a copending application of James B. Cockroft, Ser. No. 645,330 filed on June 12, 1967, and assigned to the same assignee as the present application.

An automatic blender may contain upwards of 10 or more controls all of which must be set by the user to obtain certain selected operations, Heretofore the user had available a set of instructions such as a recipe book showing how the controls should be set to cause the blender to perform in the desired manner for performing certain operations. Unfortunately, the users, many times housewives, fail to take advantage of the functions which the blender will perform, not wishing to be bothered with manipulating these controls every time they use a blender. Other housewives will use the blenders only in the conventional manner, and will not take advantage of the automatic controls permitting them to perform all of the special tasks which a blender is capable of handling.

A primary object of the present invention is the provision of a blender which may have no external controls whatsoever, but that can still perform all of the operations which a blender can selectively perform.

A further object of the present invention is to provide a blender which can be programmed to perform numerous selected tasks in accordance with certain programming means.

Another object of the present invention is to provide, for use with such a blender, a series of programming means in the form of insertable cards, each of which bears printed instructions which might be termed a recipe, and also an array of perforations which can program the blender to function in accordance with the requirements of the printed instructions.

In accordance with these and many other objects, a preferred embodiment of the present invention comprises briefly an automatic blender effectively having no controls on its control panel. It should be understood that such a blender may include one or two simple manual controls on its control panel, but to illustrate the present invention no such manual controls are illustrated. In accordance with the present invention a set of program or recipe cards are provided, each of which contains a different set of instructions, including instructions disposed in a form capable of being sensed by the blender, as, for example, perforations in the cards. When it is desired to prepare food in accordance with one of the control or recipe cards, the selected card is simply inserted into a slot provided on the blender. In the illustrated embodiment the card is pushed into the blender until it stops. The blender automatically begins to function in accordance with the requirements of the particular card. In addition to prepunched cards, blank cards having knockout-type perforations can also be used, so that the user can prepare cards for a particular use not otherwise available. Such cards would be supplied for selectively performing particular tasks, such as blending, chopping, grating, or the like, in the optimum manner.

To accomplish the above objects, there is mounted within the front panel of the blender a plurality of spring brushes oriented in such a manner that when a perforated recipe card is pushed into the slot, those spring brushes adjacent perforations in the recipe card extend through the perforations, while spring brushes not adjacent perforations are depressed and prevented from extending through the recipe card. On the opposite side of the programmed card from these spring brushes there is mounted a printed circuit board upon which are located a plurality of metallic contact surfaces, one opposing each of the spring brushes. At those locations where the spring brushes are allowed to pass through perforations in the programming card, an electrical connection is made between a contact surface and a spring brush. At other locations, the recipe card prevents the spring brushes from touching the adjacent contact surfaces. The recipe card thus sets up an electrical network which causes the blender motor to perform in the desired manner.

The control further includes two spring switch members mounted upon the printed circuit board. The first switch member is mounted in such a way that it is bent down and forced against a contact surface on the printed circuit board whenever a programming card is fully inserted into tee slot provided to receive the card. This switch member functions as a power switch for the blender, and deenergizes the blender whenever there is no recipe card inserted into the blender. The second switch member, also mounted upon the printed circuit board, momentarily makes electrical contact with a stationary contact when a card is pushed all the way into the slot in the blender. This second switch member also acts as a spring, and when the person inserting the recipe card releases his grip upon the card, this second switch member pushes the card a short distance out of the blender slot, and thus is able to break its electrical connection when the recipe card is released. This switch member functions as a START switch which starts the timing circuit within the programmable blender whenever a timed operation is to be performed.

Further objects and advantages of the present invention will become apparent as the following description proceeds, and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming a part of this application.

For a better understanding of the present invention reference may be had to the accompanying drawings in which:

FIG. 1 is a perspective view of a blender embodying the teachings of the present invention;

FIG. 2 is an instruction or program card for use with the blender shown in FIG. 1, having a particular set of instructions contained thereon;

FIG. 3 is a schematic diagram of the control circuit for the blender shown in FIG. 1;

FIG. 4 is an enlarged elevational view of the back side of the front panel of the blender shown in FIG. 1 showing the card of FIG. 2 in controlling position;

FIG. 5 is a somewhat schematic plan view of the printed circuit board and switch assembly designed to be mounted adjacent the back side of the front panel shown in FIG. 4, showing the card of FIG. 2 in controlling position;

FIG. 6 is an enlarged sectional view taken on line 6--6 of FIG. 5; and

FIG. 7 is an enlarged view partly in section taken on line 7--7 of FIG. 4.

Referring now to the drawings, FIG. 1 shows a programmable blender 10 designed in accordance with the teachings of the present invention. The blender 10 includes a removable food container 12, a lid 14 for the container 12 and a base 16 containing a motor (not shown in FIG. 1 but shown schematically as 24 in FIG. 3 of the drawings). A front panel assembly 18 (FIGS. 1 and 4) includes a slot 20 into which any one of a series of perforated control cards such as 22 (FIG. 2) can be inserted. The card 22 includes an enlarged portion 22a upon which is printed a recipe, or alternatively, information as to the control function performed by this particular card. The card shown in FIG. 2, for example, includes instructions on the preparation of regular grind coffee with the blender 10. A smaller portion 22b of the card 22 contains a series of perforations or holes 28. In FIG. 2 five holes 28 are illustratively shown and are designated as 28a, 28b, 28c, 28d and 28e. These holes 28 are so arranged that they effectively provide a specific program for the blender 10, or furnish the blender 10 with instructions causing the motor 24 thereof to operate at the proper speed for a predetermined interval of time. For illustrative purposes, more holes are shown on the card 22 than would normally be present.

Referring now to FIG. 4 of the drawings, the rear side of the front panel assembly 18 is shown. In order to make clear how this panel assembly 18 interacts with the perforated recipe cards 22, the typical card 22 (FIG. 2) is shown in dashed lines in FIG. 4 in the position in which it would occupy when fully inserted into the front panel 18. The perforations 28 in the card 22 are shown in FIG. 4 as dashed circles.

FIG. 4 also shows a plurality of spring wire brushes, seventeen being illustrated and designated as 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 59, and 60, respectively. These brushes are mounted within the front panel assembly 18 so as to press outwardly against the recipe card 22. In one embodiment built in accordance with the present invention, these spring wire brushes were constructed from 0.0063 inch-diameter spring-tempered phosphor-bronze wire. Each brush comprised a plurality of wires all of which were inserted into suitable openings defined in one of three supporting plates designated as 63, 64 and 66 (FIGS. 4 and 7). These supporting plates had a plurality of openings, such as 68 (FIG. 7), defined therein for receiving the wires forming the brushes. These openings, as best shown in FIG. 7 of the drawings, were disposed at an angle of 45.degree. relative to the plane of the plate, such as 63, whereby the inherent resilience of the wires forming the brushes is used to cause them to engage any inserted card such as 22. In said one embodiment, the plates 63, 64 and 66 were formed of brass and the brushes were soldered into their respective openings 68, which were of the order of 0.020 inches in diameter, accommodating six wires in each brush. The soldering of the wires to the plates 63, 64 and 66 had to be done carefully so that the wires defining the brushes were not annealed by the heat. As best shown in FIG. 7 of the drawings, the free ends of the wires comprising each brush were trimmed so that they fell within a vertical plane parallel to the plane defined by supporting plates 63, 64 and 66. This plane was spaced approximately 0.312 inches from the adjacent surfaces of the plates 63, 64 and 66.

As shown in FIG. 4 of the drawings, brushes 36, 50, 58, 40 and 59, for the particular card 22 illustrated in FIG. 2 of the drawings, are disposed adjacent the openings or perforations 28a, 28c, 28b, 28d and 28e, respectively, in the card 22. These brushes extend through the perforations 28 and are able electrically to engage contact surfaces (not shown in FIG. 4, but shown in FIG. 5) positioned on the other side of the recipe card 22. The remaining spring wire brushes are depressed by the presence of the recipe card 22 and are unable to make connection with adjoining contact surfaces (not shown in FIG. 4). The plate 63 is illustrated as supporting five brushes, the plate 64 as supporting 10 brushes, and the plate 66 as supporting two brushes. A blender may employ only one of these plates or combinations of plate 63, 64 or 66.

In order to complete certain circuits through the brushes 30 to 60 described above, there are contact surfaces which are located on the foil side of a printed circuit board 70, shown in FIG. 5. The printed circuit board 70 is shaped so that it can fit snugly into the back side of the front panel assembly 18 (shown in FIG. 4). Moreover, the printed circuit board 70 is mounted within the blender 10 so that the foil side of the circuit board 70 faces towards the front panel 18, in other words so the faces shown in FIGS. 4 and 5 are adjacent each other. The circuit board 70 and the front panel 18 thus form a single, compact unit. As an aid to visualizing the exact relative placements of the circuit board 70, the front panel 18, and the program of control card 22, the position of the card 22 is again indicated in dashed lines in FIG. 5. It is shown positioned as though it were fully inserted into the slot 20 in the blender 10, so as to come in contact with a spring pin 71 forming part of a momentarily actuable timing switch described in greater detail hereinafter.

The contact surfaces on the printed circuit board 70 have been assigned reference numerals 30a, 32a, 34a, 36a, 38a, 40a, 42a, 44a, 46a, 48a, 50a, 52a, 54a, 56a, 58a, 59a and 60a, respectively, and are adapted to make contact with the corresponding brush of the same reference numeral but without the alphabetical subscript. Thus when the unit is assembled, contact surface 30a (FIG. 5) is adjacent wire brush 30 (FIG. 4), contact surface 32a (FIG. 5) is adjacent wire brush 32 (FIG. 4), contact surface 34a (FIG. 5) is adjacent wire brush 34 (FIG. 4), and so on. Thus, when no recipe card 22 is present, all of the wire brushes 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 59 and 60 make electrical contact with their respective contact surfaces 30a, 32a, 34a , 36a, 38a, 40a, 42a, 44a, 46a, 48a, 50a, 52a, 54a, 56a, 58a, 59a, and 60a. When a recipe card 22 is inserted as shown in FIGS. 4 and 5, only those spring brushes adjacent to perforations 28 in the recipe card are able to engage and hence complete electrical connections with their associated contact surfaces. The recipe card 22, for example, includes perforations opposite the contacting surfaces 36a, 50a, 58a, 40a, and 59a, which correspond to the wire brushes 36, 50, 58, 40 and 59. Hence, only the above-mentioned five wire brushes are able to electrically contact their associated contact surfaces.

The control circuitry for the blender 10 is schematically shown in FIG. 3 of the drawings, and is indicated generally by the reference number 72. With the exception of the motor 24 and the brushes 30 to 60, this circuitry is entirely mounted upon the printed circuit board 70 shown in FIG. 5. The entire control circuitry 72 for the blender 10 thus mounts very neatly within the front panel assembly 18 and leaves plenty of room for the motor 24 within the base 16 of the blender 10. The control circuitry 72 includes the brushes 30 to 60. These brushes are schematically illustrated in FIG. 3 of the drawings and are designated by the same reference numerals as in FIG. 4 of the drawings. The corresponding contact surfaces 30a to 60a are also schematically illustrated in FIG. 3, and are designated by the same reference numerals as in FIG. 5 of the drawings. In addition, the control circuit includes a card-actuated master control switch 78-80 and a card-actuated momentary switch 88-90 both of which are designed to be actuated by the insertion of a card such as the card 22.

The structure of master switch 78-80 including movable switch member 78 and the associated contact surface 80 is structurally shown in FIGS. 5 and 6 of the drawings. The contact surface 80 comprises a foil section of the printed circuit board 70. As best shown in FIG. 6 of the drawings, the movable switch member 78 preferably comprises a member of spring-tempered beryllium-copper that is attached to the printed circuit board 70 by two screws 82. This member is attached to the nonplated side of the printed circuit board 70, an and is arranged so that it extends through an elongated opening 84 (FIGS. 5 and 6) in the circuit board 70 to a location adjacent the contact surface 80. The member 78 includes a central camming surface 78a which is engageable by the card 22 when it is inserted into the slot 20 in the front panel 18. As shown in FIG. 6 the leading edge of the card 22 engages and depresses the member 78 and forces the free contact end 78b thereof into electrical contact with the surface 80. This closes the master switch, connects the programmable blender 10 to a suitable power source designated as 86 (FIG. 3), and conditions the blender 10 for operation.

The card-actuated momentary switch 88-90 is provided for the purpose of initiating operation of the timing circuit. This switch comprises a card-actuated momentary switch member 88 and a contact member 90, both of which are indicated schematically in FIG. 3 and shown structurally in FIG. 5. The contact member 90 comprises a fixed post secured to the printed circuit board 70. It may comprise a rivet made of brass, copper, or other good conducting material and is mounted upon the foil-covered section of the printed circuit board 70. The momentarily actuated switch member 88 is preferably made of spring-tempered beryllium-copper and, as illustrated, is formed in the shape of a V with the apex of the V designated as 88a. One end 88b of switch member 88 is effectively stationary and includes a portion that passes through an opening 91 in the printed circuit board 70 where it is soldered to the foil surface. Close to the apex portion 88a, a brass spring pin 71 is attached to the switch member 88. This pin 71 is engageable by the leading edge of the card 22 and extends into an elongated slot 94 in the printed circuit board 70. The slot 94 and the opening 91 are so located as to stress the switch member 88 to cause the pin 71 to be biased toward the right-hand-most edge of the slot 94, and to cause the member 88 to be biased out of contacting engagement with the contact member 90.

When a card 22 is inserted all the way into the slot 20 in the front panel 18, the upper portion of the leading edge of card 22, as viewed in FIG. 5 of the drawings, moves into engagement with the pin 71 and forces it to the left. This flexes the member 88 in such a manner that the member 88 electrically engages the contact member 90. As soon as the person inserting the card 22 into the slot 20 in the front panel 18 has fully inserted the card and released it, the card 22 is forced outwardly from the blender 10 a short distance by the spring action of the switch member 88 until the pin 71 once again engages the right-hand portion of the elongated slot 94. Thus, the switch 88-90 closes only momentarily when a card 22 is first inserted into the slot 20, and opens immediately upon release of the card. Momentary closure of this switch 88-90 sets up the timing circuitry within the blender 10, as will be explained hereinafter.

It will be understood from the above description that when no card 22 is present in the slot 20 of the blender 10, all of the switches 30 and 60 defined by brushes 30 to 60 and corresponding contact surfaces 30a to 60a are closed. The insertion of a card 22 opens each of these switches except for those positioned adjacent a perforation in the card, as explained above. The other electrical elements embodied in the control circuit 72 will be described in connection with describing the operation of this circuit.

Referring now to FIG. 3 of the drawings, power from source 86 is applied to the motor 24 through a series circuit, comprising the master control switch 78-80 and a silicon-controlled rectifier 96. As explained above, the master control switch 78-80 is closed when a card 22 is inserted into the slot 20 in the front panel 18 (FIG. 1). Power is then continuously supplied from source 86 through the serially connected motor 24 and silicon-controlled rectifier 96, and operation of the motor 24 is entirely controlled by the rectifier 96. Control signals for the rectifier 96 are generated by the remaining portions of the circuit 72. The particular perforations 28 in the card 22 (FIG. 2) determine which of the switches 30 to 60 are closed and which of these switches are open, and thus determines what kind of control signals are supplied to the controlled rectifier 96. It is possible to cause the motor 24 to operate in any desired manner by providing the proper combination of perforations in the card 22.

As is clearly shown in FIG. 3 of the drawings, the brushes 30, 32, 34, 36 and 38 provide switch members which determine the speed at which the motor 24 rotates. These switch members control the effectiveness of five serially connected resistors 100, 102, 104, 106 and 108. When switch 38-38a is closed, only the resistor 100 is effective. Various combinations of these resistors 100 to 108 are rendered effective in dependence upon the condition of the switches 30-30a to 38-38a. These switches thus control the magnitude of the resistance connected between a first node 110, common to both the motor 24 and to the anode 111 of the silicon-controlled rectifier 96, and a second node 112. This second node 112 is connected by a four-layer diode 114 to a control terminal 116 of the silicon-controlled rectifier 96, and by a capacitor 118 to the cathode 119 of the silicon-controlled rectifier 96. The particular magnitude of the resistance connected into the circuit is determined by which of the switches 30-30a, 32-32a, 34-34a, 36-36a, and 38-38a is closed, and by the values of the serially connected resistors 100 to 108.

This portion of the circuit 72 functions by producing a time delay between the beginning of each positive half cycle of electrical energy and the time when the controlled rectifier 96 is rendered conductive. The specific time delay is determined by the time it takes the resistance connected between the nodes 110 and 112 to charge the capacitor 118 sufficiently to trigger the four-layer diode 114, which in turn then triggers the controlled rectifier 96. A diode 122 connected in series with the resistors 100, 102, 104, 106 and 108 prevents a reverse charge from being supplied to the capacitor 118, and a resistor 124 connected between cathode 119 and the control terminal 116 prevents the controlled rectifier 96 from triggering prematurely on leakage current from the four-layer diode 114.

For the purpose of effectively controlling the operation of controlled rectifier 96, there is provided a second silicon-controlled rectifier 126. This element 126 functions as a start and stop switch that controls the operation of the first silicon controlled rectifier 96. When the second controlled rectifier 126 is in a conductive state, it clamps the node 112 to the cathode 119. This prevents the potential at the node 112 from ever building up to a level sufficiently positive to trigger the four-layer diode 114 and the controlled rectifier 96, and thus prevents any current from flowing through the motor 24. When the controlled rectifier 126 is nonconductive, it has no effect upon the operation of the motor-speed control circuit described above, and the motor 24 runs at a speed determined by the particular combination of switches 30-30a, 32-32a, 34-34a, 36-36a and 38-38a which are opened by virtue of the insertion of a particular card 22 into slot 20.

The controlled rectifier 126 includes a control terminal 128 which connects to the output of a simple OR gate comprising the two diodes 130 and 132. The diode 130 connects to a timing node 134 in the timing portion of the circuit 72, and the diode 132 connects through circuit elements 137 and 139 to an intermittent node 136 in the portion of the circuit 72 which controls intermittent operation of the motor 24. When either the timing node 134 or the intermittent node 136 is sufficiently positive, current flows into the control electrode 128 and, by rendering the second controlled rectifier 126 conductive, stops the flow of current through the first controlled rectifier 96 and thereby stops the operation of the motor 24.

The timing portion of the circuit 72 includes three branches all of which connect to the timing node 134. Two of these branches are described in this paragraph. The first branch is the timing capacitor branch comprising a resistor 138 connected in series with a capacitor 140 between the timing node 134 and the cathode 119. The second branch comprises a resistor 142 connected in series with a diode 144 between the timing node 134 and a power input node 143. At the beginning of a timing interval, the capacitor 140 is negatively charged by circuitry, which will be described hereinafter, so as to bias the timing node 134 negative with respect to the cathode 119. During successive positive half cycles, current flows through the diode 144, resistors 142 and 138, and the capacitor 140. Eventually this current flow adds enough positive charge to the capacitor 140 so that the timing node 134 goes positive with respect to the cathode 119. Current flow from the node 134 through the diode 130 then triggers the second controlled rectifier 126 and stops the blender motor 24 in the manner explained above.

The diode 144 prevents charge from flowing out of the capacitor 140 during negative half cycles. The resistor 142 has a large enough ohmic value so that it takes a relatively long time for the capacitor 140 to charge. The length of time during which the motor 24 operates is determined by the time constant of the circuit comprising elements 138, 140 and 142, and also by the magnitude of the negative charge initially applied to the capacitor 140.

The third branch within the timing portion of the motor control circuit 72 comprises the switches 40-40a, 42-42a, 44-44a, 46-46a, 48-48a, 50-50a, 52-52a and 54-54a previously described, a voltage divider 145 including serially connected resistors 146, 148, 150, 152, 154, 156, 158 and 164, and a series circuit 159 including the switch 88-90, a diode 160, and a resistor 162. One end of the resistor 164 is connected to the cathode 119, and the resistors 146, 148, 150, 152, 154, 156 and 158 are serially connected to the other end of the resistor 164 to form the voltage divider 145. Nodes within this voltage divider 145 are connected to the power input node 143 by the switches 40 through 54, and the amplitude of the potential which appears across the resistor 164 is thus dependent upon the condition of the switches including brushes 40 to 54. The series circuit 159 connects the node common to resistors 158 and 164 to the node 134, and thus applies this variable amplitude potential to the timing node 134 whenever the switch 88-90 is closed. The diode 160 prevents reverse current through the resistor 162 from discharging the capacitor 140.

As noted above, the switch member 88 strikes the contact surface 90 momentarily when a card 22 (FIG. 2) is pushed all the way into the slot 20 in the front panel 18 of the programmable blender 10 (FIG. 1). While the switch member 88 is momentarily touching the contact surface 90 and during a negative half cycle of input current, current flows from the source 86, through the switch 78-80, the capacitor 140, the resistors 138 and 162, the diode 160, the switch 88-90, and the voltage-divider circuit 145, and back to the source 86. This current leaves a negative charge in the capacitor 140. The values of the resistors in the voltage-divider circuit 145 have low ohmic values so this is a rapid charging operation which takes no more than a fraction of a second. The magnitude of the negative charge applied to the capacitor 140 is determined by the amplitude of the potential which appears across the resistor 164 and which is applied to the capacitor 140 by closure of the switch 88-90. As was noted above, this potential in turn is determined by which of the switches comprising brushes 40, 42, 44, 46, 48, 50, 52 or 54 is closed. Thus, the length of time during which the motor 24 is allowed to operate after a card 22 is inserted into the slot 20 of the programmable blender 10 is determined by the particular switch 40-40a to 54-54a which is allowed to close by having its associated brush positioned opposite a perforation 28 in the card 22.

In order to operate the blender motor 24 continuously, there is provided the switch 58-58a which overrides the motor timing circuit. Thus, when it is desired to have the blender motor 24 operate continuously, a particular perforation 28 is positioned so as to allow the switch 58 to close. This switch 58, when closed, permanently connects the timing node 134 to the supply node 143 through a series circuit 161 comprising resistor 168, the diode 160, and the resistor 162. The diode 160 becomes conductive only during negative half cycles, so during each negative half cycle this series circuit 161 applies a new negative charge to the capacitor 140. The timing node 134 is thus never allowed to go positive and therefore can never supply a positive current to the trigger terminal 128 of the second controlled rectifier 126. Hence, when the switch 58 is closed, the motor 24 operates continuously at a speed determined by the condition of the switches 30-30a, 32-32a, 34-34a, 36-36a, and 38-38a.

For the purpose of causing intermittent operation of motor 24, there is provided the switch 56-56a. When this switch 56-56a is closed by having its brush adjacent a perforation 28 in the card 22, current flows during positive half cycles through a series circuit 169 comprising resistor 170, a diode 172, and a second timing capacitor 174 which connects to the cathode 119. The diode 172 allows this current to flow only during positive half cycles, so a positive potential is slowly built up across the capacitor 174. This positive potential appears at the intermittent node 136. When this positive voltage exceeds the conduction threshold potential of a glow lamp 137, the glow lamp becomes conductive and creates a conduction path from the capacitor 174, through a series circuit 131 which includes the glow lamp 137, a resistor 139, and the diode 132 into the control electrode 128 of the controlled rectifier 126. This causes the controlled rectifier 126 to conduct and to terminate the operation of the motor 24 temporarily. The time during which operation of the motor 24 remains terminated is determined by the value of the resistor 139, which determines the rate at which the capacitor 174 discharges. When the capacitor 174 had discharged to a potential level at which conduction within the glow lamp 137 cannot be maintained, the flow lamp 137 becomes nonconductive and allows the controlled rectifier 126 to turn off. The motor 24 then begins to function once more in the usual manner, and the capacitor 174 again begins to charge. Hence, whenever the switch 56-56a is closed, the motor 24 intermittently stops and restarts during the entire time interval it is allowed to operate by the motor timing circuitry.

Very short blender operation timing intervals can be provided by inserting a card 22 containing a perforation opposite the brush 59 into the blender 10. The switch 59-59a then closes and connects a resistor 171 directly across the timing capacitor 140. This resistor greatly shortens the time interval during which the motor runs. Usually a perforation is also provided opposite the brush 46. Each time a card 22 prepared in this manner is pushed all the way into the slot 20 (FIG. 1), the blender motor 24 is "pulsed" or turned on for a short time, and is then turned off again. This can be accomplished by any motor speed.

The switch 60-60a is used to discharge the timing capacitor 140 through a resistor 173 in case a recipe card 22 is removed from the slot 20 before a timing cycle has run its course. The brush 60 comes in contact with the contact surface 60a whenever a card 22 is removed from the blender 10.

As illustrated in FIG. 3 of the drawings, the switch members or spring brushes 40, 42, 44, 46, 48, 50, 52 and 54 are all connected to the supply node 143. These spring brushes are all mounted upon the single supporting plate 64 as shown in FIG. 4. Electrical contact with base plate 64 may be made by means of a contact shoe 180 which is mounted within the front panel 18. A wire (not shown) then connects the contact shoe 180 to the supply node 143 in the circuit of FIG. 3. The switch members or brushes 30, 32, 34, 36 and 38 also have a common node connection 110 as shown in FIG. 3, and can also be mounted upon a common supporting plate 63, as shown in FIG. 4 of the drawings. Electrical connection to the plate 63 may be made by means of a second contact shoe 182. A second wire (not shown) connects the contact shoe 182 to a point on the printed circuit board 70 (FIG. 5) corresponding to the node 110 in the circuit of FIG. 3. A third set of two spring brushes 59 and 60 are mounted upon a supporting plate 66 which receives current from third contact shoe 184. The contact shoe 184 is connected by means of a wire (not shown) to the node formed by the junction of the timing capacitor 140 with the resistor 138.

In view of the above description it will be apparent that upon inserting a card 22 having a proper combination of perforations 28 therein into the slot 20 of the programmable blender 10, it is possible to cause the blender 10 to run at any desired speed for any desired length of time, either continuously or intermittently. The housewife thus has no controls to set. She needs only to select the card corresponding to the dish which she intends to prepare and to insert the card into the blender. A large number of these cards can be kept in a box similar to a recipe box so that the housewife can easily flip through the cards and find the one desired. To aid the housewife in handling her own recipes, special blank cards are provided including knockouts over each possible location where a perforation can be placed, and also containing instructions as to which knockouts should be removed in order to obtain any desired result. Thus, the housewife is not limited to the use of cards supplied by the manufacturer, but may prepare her own cards in accordance with her own desire and needs.

It will be understood that various circuit arrangements and various circuit constants may be employed in connection with the arrangement of the present invention. In order, however, to illustrate the relative magnitudes of the principal elements of a typical circuit arrangement which has been found to satisfactorily embody the present invention the following approximate values of such elements, together with other pertinent information, are given for a particular device. It should be understood that these values are given by way of example only and not by way of limitation.

Neon Glow Lamp 137 NE-2 Silicon Controlled Rectifier 96 2N4442 Silicon Controlled Rectifier 126 TSW 300 4-Layer Trigger Diode 114 MFT32 Capacitor 118 0.1 microfarad Capacitor 140 2.2 microfarad Capacitor 174 1.0 microfarad Resistor 100 33,000 ohms Resistor 102 68,000 ohms Resistor 104 68,000 ohms Resistor 106 68,000 ohms Resistor 108 33,000 ohms Resistor 124 150 ohms Resistor 138 1 megohms Resistor 139 22,000 ohms Resistor 142 20 megohms Resistor 146 330,000 ohms Resistor 148 150,000 ohms Resistor 150 150,000 ohms Resistor 152 100,000 ohms Resistor 154 100,000 ohms Resistor 156 68,000 ohms Resistor 158 47,000 ohms Resistor 162 15 ohms Resistor 164 68,000 ohms Resistor 168 15,000 ohms Resistor 170 68,000 ohms Resistor 171 330,000 ohms Resistor 173 4,700 ohms

Although the present invention has been described with reference to an illustrated embodiment thereof, it should be understood that numerous modifications and changes will readily occur to those skilled in the art.

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