Electrically Heated Window With A Connector Block And A Circuit Breaker

Abstract

An electrically heated window including an insulated corner gusset having an electrical lead extending therethrough to supply electrical power to one sheet of a plurality of parallely-arranged sheets of glass, one of which has been coated with an electroconductive transparent coating, and from which the supply of electrical power is removed upon a breakage of the glass sheet having the electroconductive coating, thus avoiding the possibility of an individual being subjected to an electrical shock by coming into contact with the broken glass.

Description

BACKGROUND OF THE INVENTION

Electrically heated window units are in common usage, particularly in cabinet structures which are refrigerated. Usually, such window units comprise a plurality of sheets of glass arranged parallel to one another with a space therebetween which can, when desired, be evacuated to form a dead air space therebetween in order to improve the insulating properties of the double-walled window unit. When window units of this type are used in refrigerated cabinets, it is desired to heat, in some manner, the sheet of glass which is exposed to the room temperature so as to avoid the formation of condensation thereon which would obstruct vision through the glass unit. The obstruction of vision through the glass unit is most undesirable, particularly where such glass units are employed in refrigerated cabinets which contain therein items on display and it is desirous that the customer have an unimpeded view of such items.

In instances where an electrically heated pane of glass is employed in the formation of a unit comprising a plurality of parallely-arranged sheets of glass, some means must be provided for shutting off the flow of electrical current to the glass when, for any reason, the glass becomes broken, thus making possible the shocking of anyone coming in contact with the broken pane of glass.

Some attempts have been made to safeguard against such occurrences, as shown, for example, in prior U.S. Pat. No. 3,379,859 and U.S. Pat. No. 3,449,551. However, these prior safeguard methods are not dependent upon the resistance offered by the electroconductive coating on the sheet of glass which is electrically heated and thus could, under certain conditions, fail to operate to cut off the source of electrical power to the glass unit with ensuing electrical shocking of one coming into contact with the broken glass.

With the above in mind, it is the primary object of the invention to provide for an automatic means designed to operate on the basis of the electrical resistance offered by the electroconductive coating on a sheet of glass to provide for the removal of the source of electrical power to the glass in the event of a breakage of such glass, thus obviating the electrical shocking of one coming in contact with the broken glass.

Another object of the invention is to provide an improved means for connecting some of the corners of the glass units with an insulating corner gusset which has extending therethrough an electrical lead which will furnish the electrical power for the electroconductive coating on the sheet of glass.

Another object of the invention is to provide an electrically heated, multiple sheet glass unit adapted particularly for use in refrigerated units which will avoid the possibility of one being subjected to an electrical shock upon the breakage of the glass sheet having a coating of an electroconductive substance thereon.

Still another object of the invention is to provide a molded corner gusset made of a suitable insulating medium with an electrical lead extending therethrough, one end of said electrical lead extending to a suitable source of electrical supply and the other end of said lead extending to a spring member which is in electrical contact with an electroconductive coating extending over the surface of one sheet of glass of a multiple glass sheet unit.

Another object of the invention is to provide a circuit breaker for an electrically heated glass unit wherein a transistorized breaker means is employed, thus making possible the adjustment of the circuit breaker to operate at variable degrees of resistance offered by the electroconductive coating on the glass which is electrically heated, thus insuring the cut-off of power means thereto upon a breakage of the coated glass unit.

Another object of the invention is to provide a means whereby a signal lamp is employed to give a visual indication regarding the working condition of the circuit breaker.

Other objects and advantages of the invention will become more apparent during the course of the following description, when taken in connection with the accompanying drawings, wherein like numerals are employed to designate like parts throughout the same.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a multisheet glass unit constructed in accordance with the present invention.

FIG. 2 is an enlarged view showing in more detail and with parts broken away, the structure shown in FIG. 1 of the drawings.

FIG. 3 is a view taken on line 3--3 of FIG. 2, looking in the direction of the arrows.

FIG. 4 is an enlarged view showing the corner gusset of the present invention.

FIG. 5 is a modification of the corner gusset shown in FIG. 4.

FIG. 6 is a diagram of the electrical circuitry of the present invention.

FIG. 7 is a view showing how all of the electrical components of FIG. 6 can be assembled in one housing.

FIG. 8 is a view of one type of potentiometer showing how the same may be mounted separately from the common housing shown in FIG. 7.

FIG. 9 is a front elevation view disclosing the potentiometer, push button and neon indicator mounted in the framework surrounding the multipane unit, and

FIG. 10 is a front elevation view showing how the neon indicator only can be mounted on the framework of the multipane unit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, there is shown therein a multipane unit 10, constructed in accordance with the teachings of the subject invention. The unit 10, preferably, comprises two parallely disposed panes 11 and 12 which can be of suitable thickness for the intended purpose for the unit. The panes are of suitable dimension and usually comprise clear glass so as to enable the same to be used in conjunction with a cabinet or like structure, such cabinet or like structure being adapted for the storage of food items therein so as to enable a purchaser to observe the items within the cabinet.

As can be appreciated, the parallely disposed panes 11 and 12 can be mounted in a suitable framework so as to be incorporated in a door, whether the same be one pivotally mounted in a suitable opening formed in the cabinet or slidably retained in a suitable trackway formed in the cabinet opening.

As seen more clearly in FIG. 3 of the drawings, panes 11 and 12 are arranged in spaced relationship by means of a spacer element 13, formed of metal or any other suitable material. The spacer 13 extends completely around the top, bottom and side walls of the aforesaid unit 10, except that at the corners where electrical leads are to be admitted into the space 14, the spacer is joined to a corner gusset 15, which will be described with more particularity hereinafter.

The spacer 13 is bonded to the glass panes 11 and 12 by means of a suitable line of adhesive extending between the spacer and the edges of the glass panes. A catalized polysulfide adhesive has been found to be very effective in accomplishing this seal, although it is apparent that other suitable adhesives could be employed for effecting the bond between the spacer and the glass panes, aforesaid.

The spacer 13 is formed with recessed areas 16 and 17, along one edge thereof and a suitable filler material 18, extends therein to further insure that the space 14, between the panes 11 and 12, will be substantially airtight.

As is usual in the employment of an electrically heated unit, constructed in accordance with the present invention, one pane thereof is provided with an electroconductive coating 19, said coating usually being applied thereon in any suitable manner. The coating 19 is adhered to the glass pane 11, within the space 14, in such a manner that when an electric current is supplied to the film, as will be hereinafter explained, the film will be heated and will, in turn, heat the glass panes 11 and 12.

Any type of electroconductive coating can be employed provided, of course, the same meets the standards of transparency and conductivity.

Referring now to FIG. 4 of the drawings, there is shown therein the improved corner gusset of the present invention. The gusset may be molded or otherwise formed of a suitable insulating material, and comprises a substantially inverse L-shaped formation with the legs of the L-shaped formation designed to be received within the ends of the spacer bar and secured therein by a suitable adhesive.

As shown in dotted lines in FIG. 4 of the drawings, the spacer 13 extends over a portion of the said gusset 15 and abuts a ledge 20. Similarly, a like spacer extends from the opposite leg of the L-shaped formation and the same abuts a ledge 21, formed on this portion of the gusset. An electrical lead 22 extends through the insulator block forming the gusset and the same may be mounted therein when the gusset is molded so as to insure an airtight connection between these parts.

Surrounding the lead 22, interiorly of the space 14, is a grommet 23 which will assist in retaining the lead 22 in proper position within the insulated corner gusset. Secured in electrical connection with the electrical lead 22, is a spring-like member 24, which is adapted to be in contact with a bus bar 25, which is positioned inwardly of the edges of the pane 11, which has the electroconductive coating thereon.

While I have described the manner of securing the gusset to but one corner of the unit 10, it will be understood that a similar corner gusset is mounted on the opposite edge of the unit so as to present a like electrical connection to the bus bar 25 extending along the other edge of the unit 10. Of course, the gusset at the opposite edge of the unit 10 will function in the same manner as previously described insofar as concerns the securing thereto of the spacers 13.

For that matter, and whenever found more desirable, the aforesaid gusset formation may be employed at all of the corners of the unit. Of course, only two such corner gussets need be formed with an electrical lead extending therethrough, as previously described, since it is only necessary that two electrical leads be in contact with the aforesaid bus bars 25 in order to provide an operable structure intended to prevent accidental electric shocking by the breakage of the glass pane having the electroconductive coating thereon. The manner in which this will be effected will be described with more particularity hereafter.

Referring now more particularly to FIG. 5 of the drawings, there is shown therein a modified type of corner gusset 15'. The gusset shown therein is adapted to be employed where a mitered joint connection is desirable between the gusset and the spacers 13'.

The gusset 15' is molded, or otherwise formed of a suitable insulating material, and is of substantially L-shaped formation with portions of the leg sections of the L-shaped formation being of reduced cross section in order to enable the mitered ends of the spacer bars 13' to be fitted thereover and adhesively, or otherwise, secured thereto in any known manner.

The gusset shown in FIG. 5 is adapted to have the spring member 24' secured thereto, as by molding the gusset of a suitable insulating material and embedding one end of the spring member therein, as shown in dotted lines in this Figure of the drawings.

An electrical lead, not shown, can be secured, in any known manner, to the spring clip, as at 22', and lead to a suitable source of electrical power.

Referring now to FIG. 6 of the drawings, there is shown therein a diagram of the electrical components employed with the present invention to provide a circuit breaker means which will be responsive to the resistance offered by the electroconductive coating on the coated pane of glass.

It should be pointed out at this time that the electrical resistance offered by any glass pane which has been coated with an electroconductive substance will vary from one pane to another. This may result from any number of reasons; one such reason being that it is almost impossible to apply a uniform coating of the electroconductive substance to successive panes of glass. Thus, for this reason alone, each such coated pane of glass will present differing resistance characteristics and it is for this reason that we have devised a circuit breaker which will be capable of operating to cut off the flow of current to the coated pane, notwithstanding the differing degree of resistance offered by any such coated pane.

Shown in FIG. 6 of the drawings, are a pair of lead lines leading to a suitable source of electrical power such as a conventional 115 V A. C. The circuit includes a wire-wound, fixed resistor 26; a wire-wound potentiometer 27; a silicone diode 28; an electrolytic capacitor 29; a carbon resistor 30; a push button 31; a triac 32, and an indicator lamp 33.

In operation, the device is connected as shown in FIG. 6 of the drawings. The input line leads from the power source and is connected through suitable connectors to a fuse box, wall outlet or the like. To set the device for operation for a glass pane having a given resistance by reason of the electroconductive coating thereon, the push button 31 is depressed, allowing current to flow through the aforesaid electroconductive coating. When the push button 31 is depressed, the indicator lamp 33 will light up, indicating the application of power to the unit. Upon release of the push button, the potentiometer 27 should be carefully adjusted to the point where the indicator lamp 33 just stays on. This may require the use of the push button more than once in order to establish a threshold point of operation for a glass pane having a given specific resistance.

Any change of more than 20 percent of the glass area, due to cracking or breaking, will then reduce the amount of current drawn through the triac 32. The lighter loading of the triac causes less current to flow through the resistor 26 and potentiometer 27 to a point less than that required to operate the triac 32. When this occurs, the current flow ceases and the indicator lamp 32 extinguishes, thus giving a visual indication that the power is off, thereby requiring a resetting of the unit by repeating the threshold setting adjustment as described above.

The resistor 30 relieves the wattage power dissipation requirements of the potentiometer 27, thus allowing a relatively small component to be used. The diode rectifier 28 rectifies the a. c. voltage tapped off the potentiometer 27 and the unsmoothed d. c. is filtered by the capacitor 29. This d. c. voltage is then applied through the current limiting gate control resistor 30 to the triac gate. When the voltage at the triac gate is at a sufficient level to initiate conduction, current will flow through the triac to the lead and to the glass pane with the electroconductive coating.

All of the aforementioned electrical components, i.e., fixed resistor 26, potentiometer 27, diode 28, capacitor 29, resistor 30, push button 31, triac 32 and indicator lamp 33, may be housed in a single container and placed at a position convenient for use, preferably, although not necessarily, at a position in close proximity to the glass to be heated. Such an arrangement of parts is shown in FIG. 7 of the drawings.

In certain types of installations, it may be desirable to disassociate the potentiometer from the remainder of the electrical apparatus, although the same is still in circuit therewith. In such cases, the same may be installed in a remote position from the remainder of the components by means of a bracket 34. In another type of installation, the indicator lamp 33 alone may be mounted on the framing 35 surrounding the glass unit, with the remainder of the electrical components mounted in a remote position from the frame assembly, such as shown in FIG. 10 of the drawings.

In some instances, by reason of the frame design, the indicator lamp 33, potentiometer 27 and push button 31, may all be mounted thereon, as shown in FIG. 9 of the drawings.

It is to be understood that in any or all of the aforesaid manners of installing the said components, the triac 32 must not be mounted too close to the heat dissipating potentiometer 27 as the heat derived therefrom would adversely affect the operation of the triac.

As stated previously, the electrically heated glass pane is usually on the room side of the cabinet and the aforesaid electrical components are designed to obviate the shocking of anyone coming in contact with a broken pane. As a further precaution, a microswitch (not shown) can be installed on a door so as to remove the power from the electroconductive coated pane when the door is opened. This will prevent the shocking of anyone should, for any reason, the inside or uncoated glass pane is broken and one could come in contact with the coated pane.

Thus, it will be seen that we have provided a safety means for an electrically heated glass pane which will insure that the power fed thereto will be interrupted upon the breaking of a pane coated with an electroconductive coating. It will also be seen that we have provided for a novel means whereby the power directed to the aforesaid coating is fed through electrical leads extending through a corner gusset of novel construction.

It will be evident that many arrangements other than those shown herein can be conceived within the scope of the invention, depending upon the particular requirements.

Claims

We claim:

1. An electrically heated window unit comprising spaced apart glass panels, spacer means extending along the edges of said panels and secured thereto, the internal face of one of said panels having an electroconductive transparent coating thereon, spaced apart bus bars in contact with said coating, corner gussets between the said spaced apart said panels carrying leads for conducting electrical current from a source of electrical energy to the said bus bars, an electrical circuit including a circuit breaker having an electrical current flow responsive electronic device and a starting push button electrically shunting and adjusting said electronic device, said electronic device shutting off the supply of electrical power to said bus bars and electroconductive coating upon the breakage of the panel having the said coating thereon.

2. The structure recited in claim 1 wherein said gusset comprises an insulating block.

3. The structure recited in claim 1 wherein said circuit breaker includes a visual signal to indicate when the electric power source to said coated pane is shut off.

4. The structure recited in claim 1 wherein said circuit breaker includes an adjustable potentiometer to adjust the circuit breaker to the resistance of the electroconductive coating on the said coated pane.

5. The structure recited in claim 1 wherein said corner gusset is mitered to receive like mitered ends of a spacer extending between the said spaced panes.