Touch blend smooth surface switch assembly

Abstract

A touch button control system for controlling the speed and functioning of a universal motor in an automatic blender is disclosed. The touch button system features a switch assembly for controlling motor speed, including a smooth surface, extremely flexible, indicia-bearing panel or cover plate which is contacted by the user so as to close selectively a plurality of switch contacts, thereby effectuating predetermined motor speeds.

Description

BACKGROUND, OBJECTS AND SUMMARY OF THE INVENTION

This invention relates to a switch assembly and more particularly to a switch assembly adapted to control a universal motor in respect to selection of the speeds of the motor so as to provide selected operations for a blender device.

There has appeared on the market during the past decade or so a great variety of automatic blenders which are designed to offer a selection of functions such as chopping, grinding, liquefying, etc. This variety of functions is enabled by reason of the fine degree of control that can be exercised over the speed of a blender motor. Typically, such fine control in discrete steps is effectuated by a push-button array at the front panel of the blender. For an example of such blender construction, reference may be made to U.S. Pat. No. 3,550,657 to Swanke. The blender device described in the Swanke patent is provided with a plurality of push-buttons which are operable effectively to control combinations of switches in such a way to select discrete speeds for the blender motor over a wide range. The push-buttons are mechanically interlocked; that is to say, only one push-button can be pushed in at a given time so as to select a particular speed for the blender motor. Moreover, the selected push-button remains in until another choice of speed has been made.

A recent refinement or improvement which has been made in push-button control is that disclosed in copending U.S. Pat. application Ser. No. 380,416, now U.S. Pat. No. 3,833,845 which application is assigned to the assignee of the present application. The invention of the aforesaid copending application achieves fine control of the motor speed by the use of simple "touch buttons," that is, control elements which eliminate complicated, mechanically interrelated parts and provide a fairly simple movable contact which makes only momentary contact with a fixed contact or contacts.

The present invention has for its primary object to provide a unique switching assembly that is especially adapted for utilization with the touch button control system of the aforesaid copending application, but which is nevertheless applicable to other types or kinds of blender devices or to the control systems associated therewith.

Yet another object of the present invention is to improve upon touch button control systems by affording the user great ease in the manipulation of the control means, i.e. the touch buttons which are used to select motor speeds for a blender or the like.

Yet another object is to enhance the ease with which the console of the blender may be cleaned by the user: thus, rather than an upstanding array of push buttons at such console, around which it is difficult to remove the dust and grime that tend to accumulate, there is simply presented a smooth surface panel or cover plate. This cover plate is extremely flexible and resilient, although strong and durable. Also, the cover plate is indicia-bearing; that is, it permanently and plainly displays the various functions to be realized by actuation; that is, by touching the particular areas at which the indicia are located, thereby to produce selection of the proper motor speed to achieve that function.

The above and other objects, features and advantages of the present invention will be understood by reference to the following description taken in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a plan view of a blender device in which the switch assembly of the present invention is shown incorporated, but prior to inclusion of the cover plate therefor.

FIG. 2 is an elevational view in section of the blender device.

FIG. 3 is a view of the indicia-bearing cover plate of the switch assembly of the present invention.

FIG. 4 is an enlarged sectional view of one of the typical touch buttons utilized in the switch assembly of the present invention.

FIG. 5 is a schematic diagram illustrating the motor control circuitry which is controlled by the touch buttons.

DESCRIPTION OF PREFERRED EMBODIMENT

Referring now to the drawing, it will first of all be understood that the switch assembly of the present invention is especially adapted to control the speed of a universal motor; more particularly, a motor having the purpose of driving a blender cutting device. Accordingly, there will be seen in FIG. 1, a blender 10 comprising a housing 20 which includes a console 22 divided into sections. The large middle section includes a plurality of touch buttons 24. The touch buttons are selectively actuated for the purpose of controlling the speed of the universal motor, not seen in FIG. 1, but shown in the circuit diagram of FIG. 4. The motor 30 is therein shown schematically since the series connecting field windings and armature of said motor are conventional. The motor 30 has its speed determined by the control device, also seen in FIG. 4, in the form of a silicon controlled rectifier 32 which is connected in series with the motor. For convenience, the control circuitry which affects the triggering of the silicon controlled rectifier 32 is generally designated 34 and includes the aforesaid touch buttons 24.

Each of the touch buttons 24 is of the particular construction illustrated in FIGS. 2 and 4. Thus, each of the touch buttons comprises a plastic cap 24A, including an integral flange 24B, and an elongated stud 24C which is adapted to pass through one of the suitable openings 38 in a printed circuit board. The plastic cap 24A projects through one of the recesses 42 which is formed in a plastic member constituting the upper wall 44 of the console 22. The circuit board 40 is designed to contain the various components of the circuit diagram of FIG. 4 and to be suitably secured to the console in spaced relationship to the upper wall 44. By reason of the biasing provided by a spring 46, the flange 24B formed at the periphery of the cap 24A is forced against the inner surface of wall 44. A bell-shaped, movable contact 48 surrounds the stud 24C and is operative to bridge the spaced contacts 50 on the circuit board 40, thereby completing a selected individual path, as will be appreciated by reference to the schematic diagram of FIG. 6, wherein like parts are shown schematically.

It will be particularly noted in FIG. 4 that the clearance between the movable contact 48 and the fixed contacts 50 on the circuit board is extremely slight, being of the order of 0.030 inches. Also it should be noted that the upper surface of the cap 24A has a convex shape and furthermore that the projection of the cap 24A above the recess 42 in the upper wall is very slight, being of the order of 0.015 inches. Accordingly, it will be appreciated that only very light touching, and concomitantly very slight travel, of the touch buttons 24 is necessary in order to effectuate contact closure. Moreover, because of the particular construction, finger actuation over a reasonably broad area is capable of producing such contact closure. This latter point will become more apparent as the description proceeds.

The indicia-bearing, switch actuating means of the switch assembly of the present invention may be appreciated by reference to FIG. 3. This switch actuating means takes the form of a cover plate 60 in one piece, although such a means could be formed of several lateral pieces or sections. Essentially, the periphery of the cover plate 60 is adapted to fit around the timer control 26 and the master control switch 28, being provided with suitable openings for this purpose. The central section of the plate designated 62, which is indicated in FIG. 3 by phantom lines, is adapted to fit over and correspond with the array of push-buttons or touch-buttons 24. The size of this array of touch-buttons is, in the example illustrated, about 3.5 inches long by about 2 inches wide.

The cover plate 60 is preferably formed as a thin laminate comprising two layers of plastic material. It has been found that polyester is the most suitable plastic material, being able to fulfill the requirements of extreme flexibility and resilience, while providing strength and durability for the cover plate. Accordingly, an exemplary cover plate 60 has been fabricated of a 13 mil Mylar vinyl base layer, with a 4 mil clear Mylar cap, or upper layer, (No. 371 acrylic). Approximately 4 mil of permanently pressure-sensitive adhesive is provided at the surface which contacts the wall 44, except that no adhesive is used within the section 62. Because of the great flexibility and resilience possessed by the cover plate, only the slightest pressure on the section 62 is required to bend or distort a selected areas so as to cause depression of the corresponding touchbutton 24 that lies beneath a particular indicia at that area representing a condition to be realized. Moreover, the flexure of the selected area on said cover plate is such that the bending or distorting effect produced therein is localized so as to cause depression of only the selected touch-button, and not of any adjacent button.

It will be especially appreciated that the switch assembly of the present invention is adapted to be utilized as part of a touch button control system as described in copending U.S. Pat. application Ser. No. 380,416 assigned to the assignee of the present invention. For a complete description of that system reference may be made to that copending application; however, since the switch assembly of the instant invention can be understood independently of the structural details of the system, only a brief description of the operation of the system will be provided here.

Actuation of a particular touch-button 24 results in applying a charge to capacitor 70 so as to produce a voltage value thereon corresponding with the voltage value picked off from the potentiometer 61 by actuation of that particular button. Accordingly, a bias voltage of sufficient magnitude is impressed on the base of transistor 78 by way of the resistor 74 to turn on transistor 78. The particular voltage selected by the touch button acts to produce a particular output impedance of transistor 78, which forms part of the RC network 79, such that capacitor 80 therein is charged positively at a predetermined rate during the positive half wave of the voltage supplied from the 115 volt AC source. The degree of conductance of transistor 78 determines this charging rate; consequently, the degree of conductance determines the point during the positive half wave at which the capacitor 80 will have charged sufficiently to produce a voltage effective to cause the Zener diode 84 to break down. Breakdown of the Zener diode results in triggering the SCR device 32 to a state of complete conduction, thereby allowing current to flow through the motor 30. The triggering of device 32 is a consequence of the discharge of capacitor 80 into the gate electrode and shunting resistance 86.

It will be appreciated that the higher the value of the bias voltage applied at the input of transistor 78, the greater will be the output conductance thereof; hence, the faster the charging rate and the earlier in the positive half wave that the device 32 will become conductive. As a consequence of a faster charging rate, the higher will be the speed obtained for motor 30. It will further be understood by those skilled in the art that, because of the isolation provided by the transistor 78, there will be no significant leakage of charge from capacitor 70 as it functions for memory purposes. Therefore, the bias voltage at the input of transistor 78 remains established until another speed choice is effected by subsequent actuation of a different touch buttom from the previous one "being remembered."

The mode of operation just described above is conveniently called the Manual Mode; that is, a mode which does not involve use of the timer 26. Such timer permits automatic operation whereby the blender is automatically shut down after the time period set by the timer has expired. As in the aforesaid Manual Mode, when the Timing Mode is desired the unit is powered up in the same manner by moving the control switch 28 from the OFF to the ON position. The timer 26 is set to a predetermined position by turning dial 107 so as to affect timer control 106. For example, let us say, the dial is set to the 30 second position out of a total of perhaps 60 seconds. When the dial 107 is thus set, the switch 110 is automatically opened thereby permitting charging of the capacitor 114. The charging rate is selected by reason of the position of the movable arm 112 on the potentiometer 108. As was the case before in the Manual Mode, the motor speed is then selected by actuation of one of the touch buttons 24. However, after a repertoire of functions has been performed and the 30 seconds timing interval has expired, the capacitor 114 will then have been charged to a point where it will produce breakdown of the Zener diode 122 in the timer circuit 120. This results in switching the transistor 124 to the conductive state such that a substantial short circuit is provided across the capacitor 70 whereby the capacitor 70 is substantially discharged. As a consequence, there is no longer sufficient bias at the base of transistor 78 and the motor 30 will stop. However, the neon lamp 102 will remain energized until control switch 28 is moved to the OFF position.

It will be appreciated that once transistor 124 has been turned on, due to the breakdown of Zener diode 122, it will remain on due to the D.C. bias then applied to the input of transistor 124 by reason of the connection from point C through resistor 113, potentiometer 108, and the conductive diode 122. At the same time, the transistor 128, coupled to transistor 124, is also turned on and is likewise kept on. The function of transistor 128 is to ensure that when the timing period set for the timer circuit has terminated, there will be no possibility of a spurious bias condition existing sufficient to turn on motor 30. This is positively ensured because of the connection from the top of capacitor 76 to the collector of transistor 128.

The transistors 124 and 128 remain on together only until either power is switched off by reason of actuation of master control switch 28 or the timer 26 is returned to the normal position, at which point switch 110 is closed.

A further mode of operation is provided for the blender 10 by an additional position for the control switch 28: namely, the Pulse position, which is the lowest position for the switch. In this position, because of the strapping connection between fixed contacts 94A and 94B, and the bridging of contacts 94B and 96B by movable contact 98B, the neon lamp 102 will again be ON and power is likewise supplied to the motor 30. However, the capacitor 70 is now out of the circuit because the line 73 is now not connected through the switch contacts 90A and 92A. Since capacitor 70 cannot therefore be charged, the motor 30 will only operate when a predetermined touch button is held down and will continue to operate only when a button is so held. It will be noted that the contact 96A is provided as part of the control switch assembly. This contact produces, upon selection of the pulse mode of operation, shorting out of capacitor 114, and hence removal of the change that may have been stored therein. This is done in order to cancel and render ineffective any timer setting that that had been previously established.

Although a particular embodiment of the switch assembly of the present invention has been illustrated, it will be understood that the invention is not limited to this particular embodiment. Moreover, it will be appreciated that the switch assembly is also useful in controlling switch contacts which in turn would control parameters other than motor speed. It will therefore be understood that many modifications of the present invention may be made by those skilled in the art..

Claims

What is claimed is:

1. A switch assembly, comprising:

a plurality of fixed and movable switch contacts having open and closed positions;

an array of separated, spring-biased, rigid touch-buttons respectively movably actuating the movable switch contacts to their closed positions with respect to said fixed contacts;

a smooth surface, extremely flexible and resilient, indicia-bearing cover plate, adapted to be contacted by a user, fitting over and contacting said array of touch-buttons so that flexure of a predetermined area on said cover plate operates selectively to depress one of said touch-buttons and to move a corresponding one of said movable contacts into its closed position;

a console having a wall provided with openings, said array of touch-buttons extending respectively through said openings and slightly above said wall said cover plate bearing on said console wall.

2. The combination as defined in claim 1, in which each of said touch-buttons includes a cap having a convex upper surface.

3. The combination as defined in claim 1, further comprising a circuit board, including said fixed contacts thereon, said fixed contacts being adapted to be momentarily contacted respectively by said movable switch contacts, each of said touch-buttons including a stud portion projecting through an opening in said circuit board.

4. The combination as defined in claim 1, in which the slight extension of said touch-buttons above the console wall is of the order of 0.015 inches.

5. The combination as defined in claim 3, in which the clearance between each of the said movable contacts and said respective fixed contacts is of the order of 0.030 inches.

6. The combination as defined in claim 1, in which said indicia-bearing cover plate is composed of a plastic material.

7. The combination as defined in claim 6, in which said cover plate is a laminate of two layers of plastic material.

8. The combination as defined in claim 6, in which said plastic material is polyester.

9. The combination as defined in claim 1, in which said array of touch-buttons is closely spaced in an area approximately 2 .times. 3.5 inches.

10. The combination as defined in claim 1, in which said cover plate is adhered to the console wall, except in the area occupied by said touch-buttons.