US3640089A

US3640089A - Household refrigerator with exterior ice service

Info

Publication number: US3640089A
Application number: US44271A
Authority: US
Inventors: Lauren L Frazier
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1970-06-08
Filing date: 1970-06-08
Publication date: 1972-02-08
Anticipated expiration: 1989-02-08
Also published as: FR2094119A1; FR2094119B1; DE2128230A1

Abstract

A refrigerator including a freezer compartment containing a combination ice dispenser and crusher, a passage for conveying ice from the crusher outlet exteriorly of the refrigerator and exterior means for operating the dispenser and crusher is provided with safety means for stopping operation of the dispenser and crusher upon the thrusting of an arm or other elongated member into the passage. This safety means comprises a proximity detection circuit including a sensing plate associated with the ice passage.

Description

United States Patent Frazier Feb. 8, 1972 [54] HOUSEHOLD REFRIGERATOR WITH EXTERIOR ICE SERVICE [72] Inventor: Lauren L. Frazier, Louisville, Ky.

[73] Assignee: General Electric Company [22] Filed: June 8, 1970 [21 Appl. No.: 44,271

[52] US. Cl. ..62/320, 192/ l 30, 307/252 N, 307/268, 340/258 [51] Int. Cl ..l-I03k 17/56, G08b 13/00 [58] Field ofSearch ..62/344, 320, 277; 317/124; 340/258; 192/84 P, 130; 307/252 N, 252 C, 268,

[56] References Cited UNITED STATES PATENTS 3,530,310 9/1970 Adelson et al. ..307/252 .1 3,304,440 2/ 1967 Sillers, Jr. ..307/268 3,537,132. 11/1970 Alvarez ..62/344 2,704,339 '3/1955 Wescott, lr.etal.. ..192/130x 3,422,415 l/l969 lchimori ..340/258 3,439,357 4/1969 Gibaja ..340/258 Primary ExaminerWilliam E. Wayner Attorney-Walter E. Rule, Francis H. Boos, Jr., Frank L. Neuhauser, Oscar B. Waddell and Joseph B. Forman [57] ABSTRACT A refrigerator including a freezer compartment containing a combination ice dispenser and crusher, a passage for conveying ice from the crusher outlet exteriorly of the refrigerator and exterior means for operating the dispenser and crusher is provided with safety means for stopping operation of the dispenser and crusher upon the thrusting of an arm or other elongated member into the passage. This safety means comprises a proximity detection circuit including a sensing plate associated with the ice passage.

10 Claims, 5 Drawing Figures PATENIED FEB 8|972 3' 640 089 sum 1 or 2 H\S ATTORUEV' mum 'amz SHEET 2 0F 2 FIGZ PIC-3.3

TIME

INVENTOR AUREN L.- FRAZ\ER HIS ATTORNEY BACKGROUND OF THE INVENTION The present invention is directed to household refrigerator cabinet including means for dispensing ice exteriorly of the cabinet.

In the copending application, Ser. No. 44,272 filed concurrently herewith in the name of Robert J. Alvarez and assigned to the same assignee as the present invention, there is described and claimed a household refrigerator including a freezer compartment containing a combination ice storage receptacle, dispenser and crusher and passage means for receiving ice from the dispenser and conveying either ice in cube form or crushed form to a service area on an exterior surface of the cabinet. In addition to means provided on the exterior surface of the cabinet for energizing the combination dispenser and crusher, there is also provided safety switch or control means for interrupting the operationof the dispenser and crusher mechanism upon the thrusting of an arm or other elongated member into service area end of the ice passage. The safety control means in accordance with the broad aspects of the Alvarez application, comprises any suitable sensing means associated with the passage such as a pressure or capacity sensing means or preferably a photoelectric switch means.

The present invention is specifically concerned with a safety control means comprising a capacity sensitive means designed to interrupt the operation of the dispenser and crusher mechanism upon a change in capacity sensed thereby when an arm or other elongated member is thrust into the service area end of the ice passage.

SUMMARY OF THE INVENTION In accordance with the illustrated embodiment of the present invention there is provided a refrigerator cabinet comprising insulated walls including a door defining a normally closed freezer compartment and a combination ice dispenser and crusher in the compartment having a discharge opening from the crusher mechanism adjacent the inner surface of the door. The door includesan ice delivery passage therethrough for receiving ice from the discharge opening and delivering of that ice to a service area on the exterior surface of the door. In addition to operating means including an actuating means exterior of the cabinet for effecting operation of the ice dispenser, there is also provided control means operable upon thrusting of an arm or other elongated electrically conductive member into the service area end of the passage for preventing operation of the dispenser. This safety control means comprises a proximity detection circuit including a sensing plate or electrode associated with the passage and circuitry adapted to prevent operation of the dispenser and crusher when the sensing plate capacitance increases due to the proximity of an electrically conducting body. The circuitry comprises a sensing circuit and a relaxation oscillator circuit for supplying a pulsating direct current voltage to the sensing circuit each of which essentially includes an anode gated silicon controlled rectifier or its equivalent. The circuitry is particularly characterized by the fact that it is insensitive to source voltage polarity and relatively insensitive to resistive input signals compared to capacitive input.

BRIEF DESCRIPTION OF THE DRAWING In the accompanying drawing:

FIG. 1 is a vertical sectional view of a portion of a household refrigerator embodying the ice service of the present invention;

FIG. 2 is a schematic diagram of a portion of the electrical control circuitry for controlling the automatic operation of the ice dispenser in accordance with the present invention;

FIG. 3 is a plot of the various voltage wave shapes of the circuit of FIG. 2;

FIG. 4 is an alternative output portion of the control circuit; and

FIG. 5 is a functional equivalent form of the sensing portion ofthe circuit of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT While the safety control concept of the present invention may be applied to any household refrigerator including an exterior ice service, it will be specifically described in its application to a refrigerator cabinet in which the front or accessible wall portion is formed by a door closing the access opening to a freezer compartment.

More specifically the invention will be described in its application to a cabinet containing, in side-by-side relationship, a freezer compartment 1 closed by a freezer door 2 and'a fresh food compartment (not shown). The door 2 includes an outer panel 3 forming the outer face of the door and having a recess 4 generally defining a service center area to which ice is delivered exteriorly of the cabinet from an ice dispenser 5 supported within the freezer compartment above thelevel of the recess 4.

The ice dispenser 5 is of the type designed to dispense crushed ice or selectively, crushed or cube ice. The illustrated ice dispenser is more fully described and claimed in the copending application of Robert J. Alvarez, Ser. No. 756,934 filed Sept. 3, I968 and assigned to the same assignee as the present invention. Briefly, it includes a receptacle 7 for receiving and storing ice pieces, generally referred to as ice cubes, produced by an automatic ice maker 8 and rotatable dispensing means 9 positioned in the receptacle and driven by a motor 10 through a speed reduction drive meansll. Upon rotation of the dispensing means, ice cubes stored in the receptacle are advanced for discharge in batches of two or three cubes through an opening 12 in the front wall of the receptacle and these ice cubes may either fall directly through a discharge opening 14 or by a proper positioning of an interceptor means (not shown) may be crushed to form crushed ice by a crusher 15 including the usual rotating crusher arms rotatable with the dispensing means 9. The dispenser 5 is positioned within the freezer compartment 1 with front end including the discharge opening 14 adjacent the inner panel 16 of the door 2.

The inner panel 16 is formed to include an inwardly extending leg 17 having a horizontal surface 18 positioned immediately below the discharge opening 14 when the door is closed. An ice passage 19 having its end in the horizontal surface portion 18 of the ledge and its outlet end extending through the top wall 21 of the recess 4 conducts ice from the dispenser to the service area upon operation of the dispensing means 9.

The passage 19 also includes a closure member 22 intermediate the upper and lower ends thereof for normally closing the passage and thereby preventing the circulation of either ambient or freezer air through the passage. This closure 22 is moved to its opened position by pressure on a pushrod 23 provided in the rear wall of the recess 4, the pushrod 23 being suitably connected through a cable drive means 25 to the closure member. Switch means also operable bythe pushrod 23 is provided for energizing the dispensing motor 10 when the pushrod is depressed or moved rearwardly to open the closure member 22. In addition to this switch means, the controls also include crusher control means for dispensing either crushed ice or ice in cube form when the motor 10 is energized.

More specifically the passage 19 comprises an upper tubular section 28, a port portion or member 29 against which the closure member 22 seats and a lower or outlet section or portion 30. The lower or outlet portion 30 and the port portion 29 are supported on the upper wall 21 of the recess 4 while the upper tubular section 28 of the passage fits within an annular flange 35 provided on the upper surface of the port portion 29.

It is desirable that the passage 19 be as short as possible in order that batches of ice will quickly pass therethrough during operation of the dispensing means 9 and of sufficient crosssectional area as to permit the passage of ice cubes therethrough without jamming.

In accordance with the present invention, the means provided for preventing operation of the dispensing means 9 and hence of the crusher driven by the dispensing means 9 comprises a capacity sensing electrode or plate 40 associated with passage 19 above closure 22 and improved circuitry for deenergizing motor 10 whenever plate 40 senses a change in capacity resulting from the insertion into passage 19 any electrically conducting foreign object or body such as a hand, toy, knife handle or the like.

Referring to FIG. 2 of the drawing, the same source of alternating current (120 v. AC) employed to operate the dispenser motor 10 is supplied through the switch 39 operated by the pushrod 23 and the coil 41 of a motor control relay switch 42 to

terminals

44 and 45 which connect to a voltage regulating circuit comprising a dropping resistor 46, a voltage regulating zener diode 47 and a rectifying diode 48. The components of the voltage regulating circuit are so arranged that its output terminal 50 is positive and its output terminal 51 is negative.

The control circuitry essentially includes a sensing or detector circuit 52 and a relaxation oscillator 53.

The sensing circuit includes an anode gated silicon-controlled rectifier (SCR) 55 with its anode 56 connected to positive terminal 50.v Its cathode 57 is connected to the negative terminal 51 through resistor 58 thereby providing output terminals 59 and 60. Its gate 61 is connected through a resistor 62 to the positive terminal 50.

The relaxation oscillator circuit 53 also comprises an anode gated SCR 63. Its anode 64 is connected to positive terminal 50 through resistor 16 and to negative terminal 51 through a capacitor 65. Its cathode 66 is connected to negative terminal 51 through resistor 67 and to the positive terminal 50 through a capacitor 68. The gate 69 of this SCR is connected through resistor 70 to a voltage divider

circuit comprising resistors

71 and 72 connected across

terminals

50, 51.

The remaining components of the circuit of FIG. 2 include a conventional cathode gated silicon-controlled rectifier 75 connected in series with a self-heating thermistor 76 and relay coil 41. The gate 77 of the SCR 75 is connected to output terminal 59 of the sensing circuit. Relay 42 includes normal closed contacts 78 and normally open contacts 79. Sensing electrode or plate 40 is connected to gate 61 of SCR 55 through a capacitor 86.

During normal operation of the dispenser, the motor 10 is controlled by switch 39 operated by rod 23, the closing of switch 39 energizing the motor through normally closed contacts 78.

Closing-of switch 39 also connects

terminals

44, 45 to the source of alternating current and the combination of zener diode 47 and dropping resistor 46 provide a clipped half sinusoidal wave voltage at

terminals

80, 51 and hence to the sensing and relaxation oscillator circuitry through rectifier diode 48.

The operation of this circuitry can best be understood with reference to FIG. 3 of the drawing in which the AC supply voltage is illustrated by curve 81 and the DC potential at

terminals

80, 51 by curve 82. In the absence of the relaxation oscillator circuit 53 and with no connection to gate 61 of the anode gated SCR 55 other than resistor 62, anode 56 and gate 61 are both positive and at essentially the same voltage level so that the anode gated SCR 55 is in the off state.

The relaxation oscillator circuit 53 is designed to superimpose on this DC potential 82, a series of voltage pulses having a fast rise time and a magnitude of a few volts.

With reference to FIG. 3, a typical maximum voltage for wave curve 82 during the positive half cycle is about 10 volts. During this period of time the gate of anode gated SCR 63 is biased at a voltage level approximately two-thirds of this supply voltage 82 by

resistors

70, 71 and 72. Capacitor 65 is charged through resistor 67. The anode'64 of the anode gated SCR 63 is connected at the junction of capacitor 65 and resistor 67 and follows the approximate wave shape depicted by 84 in FIG. 3. When the anode 64 voltage reaches a point approximately 0.6 volt greater than the gate 69 voltage, the anode gated SCR 63 switches to the on" state, discharging capacitor 65 through the anode 64-cathode 66 path of this SCR 63 and through resistor 67. Resistor 67 is a low value in the order of 100 ohms and discharges capacitor 65 very rapidly. This sudden discharge of current through resistor 67 develops a voltage pulse or spike across resistor 67 Capacitor 68 couples this voltage pulse developed at the SCR cathode 66 to the positive supply voltage. The pulse is algebraically added to the oscillator voltage supply and this resultant voltage at junction 50 is depicted by wave shape 85 in FIG. 3. Rectifying diode 48 prevents the zener diode 47 from clipping the voltage pulses added to the oscillator supply voltage. When the discharge current from capacitor 67 through SCR 63 and resistor 67 drops below the holding current of the SCR, the SCR switches off and capacitor 65 begins charging again. This cycle repeats itself as long as a positive voltage is present at terminal 50.

The resultant voltage 85 at terminal 50 is the necessary source for the operation of the sensing or detector circuit 52 which includes an isolating capacitor 86, between the gate 61 and the sensing electrode 40. Capacitor 86 is a high-voltage unit with a capacitance value in the order of several hundred picofarads to provide electrical isolation from the AC source voltage 81. Sensing electrode 40 is of such dimensions and location to provide approximately 10 picofarads to the object being sensed.

The voltage 85 causes both the anode 56 and gate 61 of SCR 55 to be pulsed periodically with a steep wave front pulse on the order of volts per microsecond rise time and a magnitude of a few volts.

When a small capacitance of the order of a few picofarads is applied to the gate 61 by the proximity of a conducting body to plate 40, each time a pulse occurs a current flows through resistor 62 and capacitor 86 to charge the applied capacitance. This current flow, dependent on the rate of rise of the pulse and the value of resistor 62 and the capacitance between plate 40 and the sensed body generates a voltage drop which appears negative at gate 61 with respect to anode 56. When the negative pulse of this voltage reaches approximately 0.6 volt, the anode gated SCR 55 switches to the on state providing an output voltage between terminals 59 and60. The output voltage between these terminals thus provides a signal in response to the presence of a capacitance connected to the gate terminal 61.

This output of the sensing circuit is utilized to trigger the conventional cathode gated SCR 75. The SCR 75 operates in the conventional mode to energize the coil 41.

Specifically, whenever plate 40 senses a body capacity in the passage 19, relay coil 41 is energized to open relay contacts 78 thereby deenergizing motor 10 and closing relay contacts 79 to complete a holding circuit for coil 41 through the closed switch 39. This holding circuit is broken only when switch 39 is again opened which can take place only by removal of the operating pressure from rod 23 and closing of closure member 22.

Preferably, the energizing circuit for coil 41 also includes the self-heating, negative temperature coefficient of resistance thermistor 76 which provides a thermal integrationor time delay of several voltage supply cycles by SCR 75 before coil 41 is energized. This prevents the operation of the safety circuit due to undesired triggering of SCR 75 by transient voltage pulses or noise on the AC power source lines.

An alternate output configuration for the sensing circuit is illustrated in FIG. 4 in which the resistor 58 is replaced by a parallel combination of a capacitor 83 and coil 87 of a reed switch 88 series connected with relay coil 41. In this embodiment of the invention triggering of anode gated SCR 55 energizes coil 81 to close switch 82 and thereby energizing relay coil 41. In this alternate configuration, capacitor 83 performs the delay function of thennistor 76.

It is also understood that the term anode gated SCR" as used with reference to

SCRs

55 and 63 is intended to cover their functional equivalent form as provided in integrated circuitry, that is as a regenerative complementary pair of transistors as illustrated in FIG. 5. Transistor 55-a is of the PNP variety and transistor 55-42 is of the NPN variety, this pair being gated by gate 61a and connected into the remaining circuitry in the same way as the anode gated

SCR

55 or 63, FIG. 5 showing such connections in connection with SCR 55. It will be recognized this function is alternately described in the semiconductor industry as, silicon-controlled switch, complementary thyristor," programmable unijunction transistor and gate-controlled switch.

From the above description, it will be seen that by employing an anode gated SCR or its functional equivalent, in the subject circuitry, the voltage pulse is not imposed on that part of the circuit carrying the output load; that is the circuit including relay coil 41. Additional advantages of the anode gated SCR are fast switching resulting in faster pulse rise times of greater magnitude than are obtainable with the usual unijunction transistor relaxation oscillators. Thus the total circuit is more sensitive to the control by plate 40.

While there has been shown and described specific embodiments of the invention, it will be understood that is is not limited thereto and it is intended by the appended claims to cover all modifications within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a refrigerator cabinet comprising a freezer compartment containing an ice dispenser and a passage for receiving ice from said dispenser and delivering it to a service area on the exterior surface of said cabinet;

operating switch means including actuating means exterior of said cabinet for normally effecting operating of said dispenser;

control means operable upon the thrusting of an arm or other elongated member into said passage to prevent operation of said dispenser by said operating switch means;

said control means comprising capacity sensing means associated with said passage, a safety switch and circuitry for operating said safety switch by said capacity sensing means;

said circuitry comprising a sensing circuit and a relaxation oscillator circuit;

said sensing circuit including an anode gated silicon-controlled rectifier for controlling the power supply to said dispenser;

said sensing circuit including means connecting the anode of said anode gated silicon-controlled rectifier and to the gate thereof through a resistor, and means connecting the gate of said anode gated silicon-controlled rectifier to said capacity sensitive means;

said relaxation oscillator circuit comprising a second anode gated silicon-controlled rectifier and a capacitor connected to the cathode thereof for supplying a positive pulsating voltage to the anode and gate of said sensing circuit anode gated silicon-controlled rectifier;

the sensing body capacity by said capacity sensing means generating a gating voltage differential between the anode and gate of said sensing circuit silicon-controlled rectifier; and

means operable upon conduction of said sensing circuit silicon-controlled rectifier for operating said safety switch to prevent operation of said dispenser by said operating switch means.

2. A refrigerator cabinet according to claim 1 in which said safety switch is normally closed and is part of a relay including a relay coil, the energization of which is controlled by said sensing circuit.

3. A refrigerator cabinet according to claim 1 in which energization of said sensing and relaxation oscillator circuits is controlled by said operating switch means.

4. A refrigerator cabinet according to claim 3 in which said relay includes a holding switch for delaying deenergization of said coil until said operating switch means is opened.

5. In a refrigerator cabinet comprising a freezer compartment containing an ice dispenser and a passage for receiving ice from said dispenser and delivering it to a service area on the exterior surface of said cabinet;

control means operable upon the thrusting of an arm or other elongated member into said operating switch means;

said sensing circuit including input terminals, an anode gated silicon-controlled rectifier, and output terminals for controlling the power supply to said dispenser;

said sensing circuit including means connecting one input terminal to the anode of said anode gated silicon-controlled rectifier and to the gate thereof through a resistor, and means connecting the gate of said anode gated silicon-controlled rectifier to said capacity sensing means;

said relaxation oscillator circuit supplying a positive pulsating voltage to said sensing circuit and comprising a second anode gated silicon-controlled rectifier having an anode connected to said one input terminal of said sensing circuit through a resistor and to the other input terminal through a capacitor and a cathode connected to said other input terminal through a second resistor and to said one input terminal through a second capacitor;

the sensing of body capacity by said capacity sensing means generating a gating voltage differential between the anode and gate of said sensing circuit silicon-controlled rectifier; and

means operable upon conduction of said sensing circuit anode gated silicon-controlled rectifier for operating said safety switch to prevent operation of said dispenser.

6. A refrigerator cabinet according to claim 5 in which said operating means also controls the power supply to said control means circuitry.

7. In arefrigerator cabinet comprising a freezer compartment containing an ice dispenser and a passage for receiving ice from said dispenser and delivering it to a service area on the exterior surface of said cabinet;

said circuitry comprising a sensing circuit including an anode gated silicon-controlled rectifier for controlling the power supply to said dispenser, the gate of which is connected to said capacity sensing means;

a regulated voltage direct current power supply having positive and negative terminals;

means connecting said positive terminal to the anode of said anode gated silicon-controlled rectifier and to the gate thereof through a resistor and means connecting said negative terminal to the cathode of said anode gated silicon-controlled rectifier through a second resistor;

a relaxation oscillator circuit for superimposing a positive pulsating voltage on the direct current voltage supplied to said sensing circuit comprised a second anode gated silicon-controlled rectifier having an anode connected to said positive terminal through a resistor and to said negato prevent operation of said dispenser.

8. A refrigerator cabinet according to claim 7 in which said operating switch means also controls the power supply to said constant voltage direct current power supply.

9. A refrigerator cabinet according to claim 8 in which said operating switch means and safety switch are series connected.

10 A refrigerator cabinet according to claim 9 including means for preventing reclosing of said safety switch while said operating switch means is closed.

Claims

1. In a refrigerator cabinet comprising a freezer compartment containing an ice dispenser and a passage for receiving ice from said dispenser and delivering it to a service area on the exterior surface of said cabinet; operating switch means including actuating means exterior of said cabinet for normally effecting operating of said dispenser; control means operable upon the thrusting of an arm or other elongated member into said passage to prevent operation of said dispenser by said operating switch means; said control means comprising capacity sensing means associated with said passage, a safety switch and circuitry for operating said safety switch by said capacity sensing means; said circuitry comprising a sensing circuit and a relaxation oscillator circuit; said sensing circuit including an anode gated silicon-controlled rectifier for controlling the power supply to said dispenser; said sensing circuit including means connecting the anode of said anode gated silicon-controlled rectifier and to the gate thereof through a resistor, and means connecting the gate of said anode gated silicon-controlled rectifier to said capacity sensitive means; said relaxation oscillator circuit comprising a second anode gated silicon-controlled rectifier and a capacitor connected to the cathode thereof for supplying a positive pulsating voltage to the anode and gate of said sensing circuit anode gated silicon-controlled rectifier; the sensing of body capacity by said capacity sensing means generating a gating voltage differential between the anode and gate of said sensing circuit silicon-controlled rectifier; and means operable upon conduction of said sensing circuit siliconcontrolled rectifier for operating said safety switch to prevent operation of said dispenser by said operating switch means.

5. In a refrigerator cabinet comprising a freezer compartment containing an ice dispenser and a passage for receiving ice from said dispenser and delivering it to a service area on the exterior surface of said cabinet; operating switch means including actuating means exterior of said cabinet for normally effecting operating of said dispenser; control means operable upon the thrusting of an arm or other elongated member into said operating switch means; said control means comprising capacity sensing means associated with said passage, a safety switch and circuitry for operating said safety switch by said capacity sensing means; said circuitry comprising a sensing circuit and a relaxation oscillator circuit; said sensing circuit including input terminals, an anode gated silicon-controlled rectifier, and output terminals for controlling the power supply to said dispenser; said sensing circuit including means connecting one input terminal to the anode of said anode gated silicon-controlled rectifier and to the gate thereof through a resistor, and means connecting the gate of said anode gated silicon-controlled rectifier to said capacity sensing means; said relaxation oscillator circuit supplying a positive pulsating voltage to said sensing circuit and comprising a second anode gated silicon-controlled rectifier having an anode connected to said one input terminal of said sensing circuit through a resistor and to the other input terminal through a capacitor and a cathode connected to said other input terminal through a second resistor and to said one input terminal through a second capacitor; the sensing of body capacity by said capacity sensing means generating a gating voltage differential between the anode and gate of said sensing circuit silicon-controlled rectifier; and means operable upon conduction of said sensing circuit anode gated silicon-controlled rectifier for operating said safety switch to prevent operation of said dispenser.

7. In a refrigerator cabinet comprising a freezer compartment containing an ice dispenser and a passage for receiving ice from said dispenser and delivering it to a serviCe area on the exterior surface of said cabinet; operating switch means including actuating means exterior of said cabinet for normally effecting operating of said dispenser; control means operable upon the thrusting of an arm or other elongated member into said passage to prevent operation of said dispenser by said operating switch means; said control means comprising capacity sensing means associated with said passage, a safety switch and circuitry for operating said safety switch by said capacity sensing means; said circuitry comprising a sensing circuit including an anode gated silicon-controlled rectifier for controlling the power supply to said dispenser, the gate of which is connected to said capacity sensing means; a regulated voltage direct current power supply having positive and negative terminals; means connecting said positive terminal to the anode of said anode gated silicon-controlled rectifier and to the gate thereof through a resistor and means connecting said negative terminal to the cathode of said anode gated silicon-controlled rectifier through a second resistor; a relaxation oscillator circuit for superimposing a positive pulsating voltage on the direct current voltage supplied to said sensing circuit comprised a second anode gated silicon-controlled rectifier having an anode connected to said positive terminal through a resistor and to said negative terminal through a capacitor, a cathode connected to said negative terminal through a second resistor and to said positive terminal through a second capacitor, and a gate connected through a third resistor to voltage dividing means connected across said terminals; the sensing of body capacity by said capacity sensing means generating a gating voltage differential between the anode and gate of said sensing circuit silicon-controlled rectifier; and means operable upon conduction of said sensing circuit silicon-controlled rectifier for opening said safety switch to prevent operation of said dispenser.

10. A refrigerator cabinet according to claim 9 including means for preventing reclosing of said safety switch while said operating switch means is closed.