Combined convex/flat mirror and wiper assembly with adjusters

An exterior rearview mirror assembly is provided for use on a vehicle which includes a rearview mirror, a wiper assembly and adjusters for the mirror. The wiper assembly includes a wiper arm base located behind the mirror assembly extending over the top of the mirror to attach to a resilient wiper arm having a wiper blade. The wiper arm base is attached to a threaded rod which, upon bi-directional rotation of the rod, causes the wiper arm base to laterally traverse across the mirror assembly, which in turn drives the wiper blade across the mirror. The adjusters are used to adjust the angular position of the mirror, or the entire mirror assembly, by utilizing spirally threaded rods which rotate bi-directionally to push or pull the mirror about certain pivot points.

BACKGROUND OF THE INVENTION 
This invention relates generally to wiping and specifically to wiping of 
rear view mirrors of vehicles such as trucks, buses, and similar vehicles 
and to adjustment of mirrors. 
The use of wipers on the rear view mirrors of large commercial vehicles is 
a potential trend in the industry. Because of their length, it is 
especially important that trucks and buses have an excellent view of what 
is beside them. Unfortunately, heavy rainfall can obscure the view in a 
standard rear view mirror. Even a heated mirror does not help in heavy 
rainfall. If a dangerous circumstance suddenly presents itself in a 
vehicle's path, the driver might not be able to tell whether it is safe to 
change lanes left or right to avoid the danger. Therefore, having clean 
mirrors can prevent accidents and save lives. 
Many patents have been issued on various inventions related to wiping of 
rear view mirrors. Yet it is still a rare sight to see a vehicle equipped 
with any of these inventions. In the absence of regulations mandating 
wipers on the external rear view mirrors of large commercial vehicles, the 
popularity and commercial success of such wipers can be expected to be 
highly price sensitive. 
Two notable patents, U.S. Pat. No. 5,179,758 and U.S. Pat. No. 5,353,466, 
assigned to the assignee of the present application address some of the 
problems in the industry and are incorporated herein by reference. The 
problem with the wiper assembly disclosed in these patents is that the 
wiper cannot be used if a convex mirror is attached to the face of the 
mirror and neither of these mirrors provide for electric adjustment. 
BRIEF SUMMARY OF THE INVENTION 
The present invention utilizes a single piece of glass with an elliptical 
shaped carved out to form a wider view to the driver of any vehicle. This 
rectangular piece of glass may have one or two elliptical shapes carved 
out of the back of the glass so the front of the glass remains flat and 
can be wiped clean to provide a clear viewing surface of both mirrors. 
The rectangular shaped glass with the elliptical shape or shapes carved out 
of the back may then be painted to provide a reflective viewing surface, 
i.e., a mirror, so that when front is clean by the unique wiper mechanism 
both reflective surfaces are useful. This glass arrangement and means to 
clean it provide a substantially improved rearview mirror over the prior 
art. The mirror assembly of the present invention also provides for 
adjustment of the mirror utilizing a novel adjustment means. 
Specifically, in a preferred embodiment, the present invention provides an 
exterior rearview mirror assembly for use on a vehicle, having a rearview 
mirror with at least one flat reflective surface and at least one convex 
reflective surface; and a substantially flat exposed outer surface over 
the reflective surfaces; a wiper assembly attached to the rearview mirror 
including at least one flexible wiper blade for wiping the outer surface 
of said rearview mirror, a driver for bidirectionally driving the wiper 
blade across the flat outer surface; and a source of power for applying 
electric power to the driver. 
In one embodiment, the convex reflective surface and the flat reflective 
surface are made from a single piece of translucent material with a 
reflective coating applied to an underside thereof In another embodiment, 
the convex reflective surface is mounted along the same plane as the flat 
reflective surface, and a single piece of translucent material extends 
over the reflective surfaces to provide the substantially flat outer 
surface. 
The mirror assembly also includes a wiper blade attached to a wiper arm 
base. The wiper arm base is preferably located behind the mirror, securely 
encased within a housing. The wiper arm base is attached to a 
bidirectional moveable device driven by the driver. In one embodiment, the 
bidirectional moveable device is composed of at least one spirally 
threaded rod inserted through a counter-threaded hole within the wiper arm 
base, and a gear. The gear provides bidirectional rotation to the rod, 
causing the wiper arm base to traverse across the rod. A pair of contacts 
are mounted along the rod near each end of the rod such that upon the base 
reaching either end while traversing the rod, one of the contacts is 
activated, causing the driver to reverse direction of the gear, thereby 
reversing rotational direction of the rod and reversing direction of the 
wiper arm base, periodically causing the blade attached thereto to 
traverse back and forth across the flat outer surface in a wiping manner. 
In another embodiment, the bidirectional moveable device is composed of a 
pulley assembly to which the wiper arm base is securely attached and at 
least one rod inserted through the base to maintain the base along a 
straight path such that the pulley provides lateral movement to the base 
across the rod. A pair of contacts are located near each end of the rod 
such that upon the base reaching either end while traversing the rod, one 
of the contacts is activated, causing the driver to reverse direction of 
the pulley assembly thereby causing the wiper arm base to reverse 
direction on the rod, periodically causing the blade attached thereto to 
traverse back and forth across the flat outer surface in a wiping manner. 
The mirror assembly also includes a device for adjusting the angular 
position of the mirror. In one embodiment, the adjustment device comprises 
a pair of adjusters located at right angles from a pivot point to provide 
both horizontal angular movement and vertical angular movement from the 
pivot point. Each of the adjusters comprises a spirally threaded rod 
inserted through a counter-threaded hole of a connector arm attached to 
the mirror; a driver attached to a stationary point of the mirror assembly 
to provide bidirectional rotational movement to the rod, such that the 
connector arm laterally traverses the rod upon rotation of the rod in 
opposing directions depending on the rotational direction of the rod, 
thereby pushing or pulling the mirror about the pivot point to change the 
angular position of the mirror. The driver for each adjuster comprises a 
belt driven gear attached to a single bidirectional motor to provide 
rotation to each driver which in turn provides bidirectional rotation to 
the rods. In an alternate embodiment, the driver for each adjuster 
comprises a bidirectional motor which rotates a series of gears which in 
turn provide bidirectional rotation to the rods. 
In a preferred embodiment, the mirror adjuster is an adjuster mounted to 
one side of a pair of vertically aligned pivot connectors to provide 
vertical angular adjustment of the mirror. The adjuster comprises a 
spirally threaded rod inserted through a counter-threaded hole of a 
connector arm attached to the mirror, and a driver attached to a 
stationary point of the mirror assembly, the driver providing 
bidirectional rotational movement to the rod, such that the connector arm 
laterally traverses the rod upon rotation of the rod in opposing 
directions depending on the rotational direction of the rod, thereby 
pushing or pulling the mirror about the pivot connectors to change the 
angular position of the mirror. 
In an alternate embodiment, the adjuster is mounted to the mirror assembly 
and a connector arm mounted to an arm of the mirror assembly and a 
stationary pivot point at the point where the mirror assembly attaches to 
the arm; the adjuster comprising a spirally threaded rod inserted through 
a counter-threaded hole of the connector arm, the adjuster further 
comprising a driver to provide bidirectional rotational movement to the 
rod, such that the connector arm laterally traverses the rod upon rotation 
of the rod in opposing directions depending on the rotational direction of 
the rod, thereby pushing or pulling the entire mirror assembly about the 
pivot point in the arm to change the angular position of the mirror 
assembly. 
In another embodiment, the mirror adjustment assembly for adjusting the 
angular position of a mirror comprises at least one adjuster mounted to a 
stationary point of the mirror assembly, the adjuster comprising a 
spirally threaded rod inserted through a counter-threaded hole in a 
connector arm; the connector arm mounted to the mirror in a spaced 
relation to a pivot point of the mirror; the adjuster further comprising a 
driver to provide bidirectional movement to the rod, such that the 
connector arm laterally traverses the rod upon rotation of the rod in 
opposing directions depending on the rotational direction of the rod, 
thereby pushing or pulling the mirror about the pivot point to change the 
angular position of the mirror. In one embodiment, the mirror adjustment 
assembly includes two adjusters mounted at right angles to the pivot point 
to provide both horizontal angular movement and vertical angular movement 
of the mirror about the pivot point, and the driver is a bidirectional 
motor which drives a series of gears attached to the rod.

DETAILED DISCLOSURE OF THE INVENTION 
Turning now to FIG. 1 wherein like numerals represent like elements 
throughout several views, the mirror assembly 1 of the present invention 
is shown. The mirror assembly is designed for use external to the vehicle 
such as a truck or bus, and may be attached to either or both sides with 
arm supports 4. Since the mirror assembly 1 is external to the vehicle, it 
is subject to environmental conditions such as rain, dirt, dust and road 
debris. The mirror assembly includes a wiper arm 2 to clean the exterior 
surface 29c of the mirror assembly 1. A sprayer 5 for spraying water or 
another cleaning solution may be located on an upper portion of the wiper 
arm 2. The sprayer 5 may tap off the window washer fluid system already 
present under the hood of most vehicles. The driver sprays the mirror 
whenever desired. At the manufacturer's option, the windshield washer 
control can activate the rearview mirror sprayer also. This eliminates the 
need for separate pumps and controls. Otherwise, a separate pump and 
control can be provided. The wiper arm 2 has attached along its length 
between the arm 2 and the mirror surface 29c a wiper blade 3 or squeegee. 
FIG. 1 shows the preferred mounting of the wiper, vertically. However, 
alternate mounting positions, such as horizontally are contemplated 
herein. One advantage of having the wiper arm 2 mounted vertically, as 
shown, is that gravity will cause rain water to run down the length of the 
wiper blade 3. The water automatically gets out of the way. Another 
advantage of a vertically mounted wiper arm 2 is that when it blocks one 
eye's view, the other eye can often see around it. The wiper arm 2 is 
designed to move along a straight path. It will move horizontally from 
side to side if mounted vertically or move vertically from top to bottom 
if mounted horizontally. Water stoppers 7 are located along the inside 
edge of the cover 6 (FIG. 2) and extend to the outer edge of the mirror 29 
and mirror edge extensions 19. 
Turning now to FIG. 3, in a preferred embodiment, the mirror 29 is a single 
piece of reflective surfacing made of glass or other materials which are 
translucent with reflective backing or are entirely reflective in nature. 
The mirror 29 has combined a flat surface 29b for reflecting a normal 
image and a convex surface 29a which curves outward to provide a 
wide-angle reflective surface along its back side. The mirror 29 has a 
continuous flat face 29c along the front, exposed side. The continuous 
flat face 29c on the exposed side may be easily and thoroughly cleaned by 
the wiper blade 3 since there are no pockets, indentations or seams 
between the flat surface 29c and the convex surface 29a. 
In an alternate embodiment shown in FIG. 4, a multi-piece mirror assembly 
20 is shown. This embodiment comprises a flat mirror 26 and a convex 
mirror 25 along the same vertical plane with a single piece of translucent 
face material 27 such as glass extending over both mirrors to provide a 
flat face 27 on the exposed side. This assembly may be laminated A seal 21 
of plastic, rubber or like material is located around the outer edges of 
both the mirrors 25, 26 and glass face 27 to prevent water or moisture 
from entering between the glass 27 and the mirrors 25, 26. A heating 
element 22 may be attached to the back of the mirror(s) 29, 20 for 
defrosting and defogging. 
Turning now to FIG. 5 the wiper arm base 8 is shown. Extension 39 connects 
the wiper arm base 8 to the wiper arm 2. The wiper arm base 8 includes at 
least one hole, preferably two through which threaded control rods 9 (FIG. 
6) or non-threaded control rods 16 (FIG. 9, 11a), or a combination thereof 
may be inserted. The wiper arm base 8 extends over the top of the mirror 
29 (or 20) such that extension 39 is exterior to the assembly for securing 
the wiper arm 2 against the exposed side of the mirror. 
Turning now to FIG. 6, the inner workings of the mirror assembly are shown 
from the back with the back cover 6 removed. The back side 10 of the 
mirror assembly preferably made of tin or other suitable material such as 
other metals or plastics has a convex indentation 29a to provide the 
convex reflecting surface. Multiple convex reflecting surfaces may be 
provided as desired. The wiper arm base 8 is located near the top of the 
assembly. Two control rods 9 extending horizontally across the assembly 
run through the wiper arm base 8. Such rods are preferably approximately 
1/4 inch to 3/8 inch in diameter. One or both of these rods 9 may be a 
spirally threaded shaft (worm). Preferably, two rods 9 are utilized to 
help stabilize the wiper arm base 8. The threaded shaft rods 9 mesh into a 
wheel with marginal teeth, e.g., worm gear 30. The worm gear 30 and rods 9 
drive the wiper arm base 8. The worm gear 30 is attached to another 
spirally threaded shaft (worm 31) attached to a shaft 32 and motor 33 or 
other driving means. As the motor 33 drives the worm 31 into the worm gear 
30, the control rods 9 cause the wiper arm base 8 to move horizontally 
across the mirror assembly. As shown in FIG. 8, this causes the wiper arm 
2 and blade 3 to wipe the exposed surface of the mirror. The backside 10 
of the mirror is preferably a thin piece of tin approximately 1/16 inch 
thick upon which the mirror is laid flat against. FIG. 6 also shows the 
adjuster assembly 15 which will be described in more detail hereafter. 
FIG. 7 shows a cross-sectional view taken along lines 7--7 of FIG. 6. 
FIGS. 9 and 10 show an alternate pulley assembly for driving the wiper arm 
base. A plastic gear 35 is provided with both timing belt teeth and gear 
teeth making it a bitooth gear. The timing belt 36 runs through the gear 
35 and around two oppositely spaced pulleys 40. Motor 44 drives gear 35 
which drives the timing belt 36. Pins 62 connect the pulley assembly to 
the mirror. In a preferred embodiment, the wiper motor is a bidirectional 
direct current motor. It is powered by a direct current electric power 
control that periodically changes polarity. Each change in polarity causes 
a change in the direction of the wiper's motion and begins a new half 
cycle. The driver controls the duration of time between half cycles with a 
multi-position frequency control. The timing belt 36 is attached to the 
wiper arm base 8 by a connector 45. As the belt 36 moves back and forth, 
the wiper arm base moves across the control rods 16 which causes the wiper 
arm 2 and blade 3 to wipe the exposed surface of the mirror. One of the 
two pulleys 40 keep the timing belt 36 in rotation. Electrical contacts 34 
are located at opposing ends of the mirror assembly. As the arm base 8 
travels across, it reaches one side and contacts one of the electrical 
contacts 34. This electrical contact 34 triggers a stop in power to the 
motor 44 which will allow the electronics to signal the motor 44 to 
reverse direction. In a preferred embodiment, a pair of normally closed 
momentary switches (not shown) are located in the assembly so that when 
one of these switches is activated the wiper reaches each end of its 
desired range of travel. Activating each switch opens one circuit that 
powers the motor's rotation in one direction only. This causes the wiper 
arm base 8 to stop until the beginning of the next half cycle when the 
polarity of electricity to the motor is reversed. If each half cycle is of 
short duration, the switches will normally not be reached during 
continuous operation. Nevertheless, they serve as a safety catch that 
protects the gears and other parts of the assembly. As the power control 
is set to longer durations (lower frequencies) each switch will be 
activated once per full cycle and the wiping will become intermittent. 
Thus, the presence of the wiper at each of two opposing extreme positions 
along said mirror is signaled and further travel in that direction is 
stopped. Every half cycle the wiper's position is automatically 
synchronized with the power control. 
A mirror edge extension 19 is provided to keep a tight seal between the 
water stoppers 7 and the mirror 29 (or 20). Preferably, the mirror edge 
extensions 19 are made of plastic or metal and extend around the edge of a 
swivel mirror about 2.5" from the exposed surface of the mirror towards 
the back. This provides a seal between the water stoppers 7 and the mirror 
edge extensions 19 when the mirror is swivelled or adjusted. 
Focusing now on FIGS. 6-8, adjustment of the mirror in one embodiment will 
now be discussed. When the mirror is to be adjusted, an adjuster button 
(not shown) is pushed. Activation of the adjuster button will engage the 
clutch motors 11. The clutch motors 11 are attached to a bidirectional 
electric motor 12 by belts 13. A pivot pole 43 is centrally located and 
consists of a metal rod which extends from the inside of the back cover 6 
to the mirror back 10. The pivot pole 43 keeps the mirror suspended while 
the mirror is adjusted to the proper position or angle for viewing. The 
clutch motors 11 are connected to adjuster assembly 15 for adjusting the 
mirror. The adjuster assembly 15 comprises a spirally threaded shaft 
(worm) 15a which meshes into a grooved connector arm 15b attached by a 
connector 15c to the mirror. The motors which drive the adjusters are 
connected to the inside of the back cover 6. The connectors 37 are 
designed to allow the adjuster at the point of connection to slide up and 
down the connector 37 to compensate for the movement in angle change from 
parallel to obtuse. One of the adjusters 15 is located to one side of the 
pivot pole 43 and the other toward the bottom forming substantially a 
right angle between the adjusters and pivot pole. As shown in FIG. 8, as 
an example, the adjuster assembly 15 has positioned the mirror in a 
downward angle by utilizing the threaded shaft 15a (as it turns) to move 
the mirror in or out. 
Alternately, FIGS. 9 and 10, two adjusters 70a, 70b connected to the back 
cover 6 of the mirror assembly by connectors 75 consist of a motor 71, 
which drives a shaft 76 which drives gear 77 which in turn meshes with 
toothed gear 78. Gear 78 causes the spirally threaded shaft 72 of the 
adjuster to turn, meshing with a grooved connector arm 73 connected to the 
mirror by connector 75. The entire assembly, is connected to the back 
cover 6 by connector frame 74. Pivot pole 43 is provided as previously 
described. 
In an alternate embodiment shown in FIGS. 11a and 11b, a single adjuster 80 
may be utilized with the same gearing as previously discussed. The single 
adjuster allows only left to right adjustment. Two connectors 81 provide 
the attachment of the adjuster 80 to the mirror at the necessary pivot 
points. 
Turning now to FIGS. 12-13, an adjuster 90 is located in the lower half of 
a mirror assembly 58. This embodiment does not contain the adjusters from 
the previously described. This adjuster is connected to three points, two 
located in the arm 60 extending to the vehicle (42, 56) and the other 
point (41) within the mirror assembly. This allows the entire mirror 
assembly to be moved in or out. 
As an alternate to the spirally threaded shaft connected to a motor which 
provides bi-directional movement discussed previously herein, a helically 
threaded shaft 50 may be used to provide bidirectional lateral movement 
while rotating the shaft only in one direction (FIG. 15). The helically 
threaded shaft 50 incorporates both ascending and descending spiral 
grooves. Reversing grooves are positioned on opposite ends of the 
helically threaded shaft 50 so that the grooved member which meshes with 
the helically threaded shaft 50 may laterally reverse directions (i.e., 
move from the ascending to the descending grooves) without having to 
change the rotational direction of the shaft. This alternate type of shaft 
may be substituted for any of the spirally threaded shafts used with 
bi-directional motors, for example, the spirally threaded shaft 15a which 
meshes into a grooved connector arm 15b, for adjustment of the mirror; or 
the threaded shaft rods 9 which mesh with the wiper arm base 8, for 
driving the wiper. 
FIGS. 14a-14e illustrate the electrical circuitry described below. 
Switch SW1 is in/off switch in the on position, current flows through the 
contact of RL2 to charge up capacitor C3 to a hold state, current also 
flows to light emitting diode LED2 on the eliminate on/off indicator. 
Current also flows from switch SW1 through the contacts of RL1 through 
Resistor Array R2 to R7 off different values selected by switch SW1A upper 
half to charge up capacitor C1. Capacitor C1 charges at a period of time 
determined by the amount of resistance obstructing the current flow to 
capacitor C1 that is selected by the upper half of switch SW1A. Capacitor 
C1 charges to activating values of RL1 resistor RL4 is used to adjust the 
Activating Range of RL1 charging cycle. 
Once the activation value of RL1 is reached, the RL1 reacts, contacts A-B 
open and current stop flow to capacitor C1. Capacitor C1 discharges 
contact D-E are closed that allows current to flow, not only through the 
coil of RL1 but also a shunt path, through the Resistor Array R8 and R13 
and the lower half of switch SW1A, capacitor C1 discharges at a period of 
time determined by the amount of resistance charge and discharge rate 
simultaneously once capacitor C1 has discharged to RL1 activates value 
ends. The discharge cycle RL1 returns to a resetting state, contact D and 
E open contact A and B close and the circuit starts another charging 
cycle. 
During the charge cycle RL1 is in a reset state, contacts J-K and M-N are 
closed, current flows from switch SW1 through diode D2, D2 is used as 
protection from inverse voltages and spikes. The current travels through 
contacts J-K through switch diodes D3-D5 blocked by diodes D4-D6 as 
current travels to LED 3 and LED 7 to eliminate Directional Travel 
Indicators and also across safety contacts switches SW3 and SW5 to active 
motors ML2 and ML1 into motion. Motor ML1 and ML2 will drive until the 
charging cycle and RL1 changes states or safety contacts SW3 and SW5 is 
reached and open the circuit, stopping the current flow motion of motors 
ML1 and ML2. ML1 and ML2 will remain until the end of the charging cycle. 
A small current bypass switches SW3 and SW5 are used to eliminate LED2 and 
LED6, the stop indicator. 
During the discharge cycle, relay RL1 is in active state, contact I-J and 
L-M are closed, electrical current flows from switch SW1 through diode D2 
to switch diodes D4 and D6 blocked by D3 and D5. Current travels to LED4 
and LED8 to eliminate the reverse Directional Travel Indicator, and also 
across safety contacts SW4 and SW6 reached and open. The current stops the 
motion of motors ML1-ML2. ML1 and ML2 will remain stopped until the 
beginning of the next cycle where a small current bypasses switches SW4 
and SW6 to eliminate LED3 and LED9, the stop indicators. 
Switch SW1 after being on is then placed in off position and a circuit path 
is connected from capacitor C3 which is in a full charge state through the 
coil of RL3-C3 discharged through the coil of RL3 that closes its contact, 
which applies current to the contact of RL1. RL1 in its rest state 
contacts switches K-J; M-N are closed, and the current flows through D3 
and D5 driving ML1 and ML2 until safety contact SW3 and SW5 are reached to 
open the circuit to permanent state of rest. During the return cycle diode 
D2 blocks current from activating the control sequences of the circuit. 
Switch SW2 controls the automatic function. Switch SW2 is normally an open 
switch with two poles. When closed, switch SW2 allows a closed circuit 
from the battery washer motor to ground to plug PL1. This tells the pump 
to spray water momentarily. Closing switch SW2 also applies a charge to 
capacitor C2. The switch SW2 is thereafter released and reopens capacitor 
C2 which discharges through R15 to the gate of SCR1. That in turn 
activates SCR1 and applies operating current to the control sequences and 
drives circuits. The system will operate until capacitor C2 discharges to 
a value that is not enough to keep SCR1 open. 
As the last current flows through SCR1, current also activates RL2 that 
applies the hold current to capacitor C3 through contacts O-P of RL2. C3 
is charged up for the return cycle. When SCR is turned off, current to the 
system stops operating, RL2 goes back to a rest state, contacts are closed 
connecting a discharge path from capacitor C3 across RL2. Contacts Q-P 
across, off switch SW1 to the coil of RL3. That closes it, contacts that 
applies current to contact of RL1 to start the return cycle. 
Direction Control Circuit is described as follows: 
Switches and motors SW7, SW8, SW9, SW10, SW11, MD1, MD2, MD3, MD4, SW7 AND 
SW8 are monitory two pole switches that control the right or left travel. 
Current flows from positive through contacts and then SW11 contacts I-H to 
activate motor MD3 and back to switch SW11 then contacts L-N then back to 
ground through SW7, and contact B. When SW8 is pushed, current flows from 
positive contact D through SW11, and contact L-N through MD3, and then 
back through SW11, and contact I-K to ground through SW8 contact C. 
Switches SW9 and SW10 are momentary two pole switches that control the up 
and down travel. When SW9 is pushed, current flows through SW9 positive 
contact E through SW11 contact R-T activating MD4 then back through SW11 
contact O-Q back to ground through SW9 contact F. This drives MD4 up. When 
SW10 is pushed, current flows through positive contact H, through SW11, 
T-R, to place MD4 into motion, then flows back to SW11, Q-O, back to 
ground through SW10 contact G. 
SW11 is a four pole, two position, switch. In its present position, motors 
MD3 and MD4 are activated with SW7 through SW10 when pushed for adjusting 
the mirror. When SW11 is switched over, contacts J-M and P-S are used in 
conjunction with MD1 and M2 for adjusting the right mirror, when switch 
SW7, SW8, SW9, SW10 is pushed. 
Mirror Heating is described as follows: 
When SW12 is closed, current is supplied to one Resistive Heating Element; 
EL1. CB1 is a circuit breaker that acts as a thermostat that limits the 
time and amount of current to EL1. CB1 will open and close causing ELI to 
heat and cool at a balance rate until S12 is open. 
It should be understood that the examples and embodiments described herein 
are for illustrative purposes only and that various modifications or 
changes in light thereof will be suggested to persons skilled in the art 
and are to be included within the spirit and purview of this application 
and the scope of the appended claims.