U.S. patent number 3,890,486 [Application Number 05/507,075] was granted by the patent office on 1975-06-17 for aquarium-tank heating control.
This patent grant is currently assigned to Equipment Development Corporation. Invention is credited to Robert C. Fitzgerald.
United States Patent |
3,890,486 |
Fitzgerald |
June 17, 1975 |
Aquarium-tank heating control
Abstract
Heating devices are provided having a resistive heating element
for heating a first region and a temperature control electrically
coupled to the resistive heating element and positioned in a second
region spaced from the first region. The temperature control is
adapted to respond to the ambient temperature at the second region
and the amount of current applied to the resistive heating element
to maintain the temperature at the first region. The resistive
heating element may consist of a length of resistive electrical
conductor distributed over an area and encapsulated in a flexible
waterproof material so as to define a sheet.
Inventors: |
Fitzgerald; Robert C. (High
Falls, NY) |
Assignee: |
Equipment Development
Corporation (New Canaan, CT)
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Family
ID: |
26999156 |
Appl.
No.: |
05/507,075 |
Filed: |
September 18, 1974 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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356224 |
May 1, 1973 |
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Current U.S.
Class: |
219/523; 219/511;
392/503; 219/442; 392/451; 119/245 |
Current CPC
Class: |
H05B
3/00 (20130101); H01H 61/02 (20130101); H05B
3/80 (20130101); A01K 63/065 (20130101) |
Current International
Class: |
A01K
63/06 (20060101); H01H 61/02 (20060101); H01H
61/00 (20060101); H05B 3/78 (20060101); H05B
3/80 (20060101); H05B 3/00 (20060101); H05b
003/06 () |
Field of
Search: |
;219/312,316,318,322,328,331,335,336,337,338,381,437,442,511,516,523,544
;119/5 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Mayewsky; Volodymyr Y.
Attorney, Agent or Firm: Hopgood, Calimafde, Kalel,
Blaustein & Lieberman
Parent Case Text
This is a continuation of application Ser. No. 356,224, filed May
1, 1973, now abandoned.
Claims
What is claimed is:
1. A heating device comprising resistive heating element means for
heating a first region; temperature control means positionable in a
second region spaced from said first region for controlling the
temperature at which said first region is maintained by said
resistive heating element means; and electrical cable means
extending between said resistive heating element means and said
temperature control means for applying current to said resistive
heating element means, said temperature control means being adapted
to control the current applied to said resistive heating element
means in response to temperature at said second region, said
temperature control means including first and second contact means;
first and second bi-metallic element means respectively carrying
said first and second contact means in facing relation for
displacement thereby into and out of engagement with each other;
and a resistive member mounted in series circuit with said contact
means and said resistive heating element means and positioned in
proximity with a side of said first bi-metallic element means
opposite to the side thereof facing said second bi-metallic element
means, so that the displacement of said first contact means by said
first bi-metallic element means is at least principally in response
to the heat generated by said resistive member and the displacement
of said second contact means by said second bi-metallic element
means is at least principally in response to the temperature at
said second region, said resistive heating element means including
a length of resistive electrical conductor means distributed over
an area; and water-proof, electrically insulating material
enclosing said length of resistive electrical conductor means.
2. A heated aquarium, comprising a fish tank, resistive heating
element means for heating a first region within said tank;
temperature control means positionable in a second region outside
of said tank for controlling the temperature at which said first
region is maintained by said resistive heating element means; and
electrical cable means extending between said resistive heating
element means and said temperature control means for applying
current to said resistive heating element means, said temperature
control means being adapted to control the current applied to said
resistive heating element means in response to temperature at said
second region, said temperature control means including first and
second contact means; first and second bi-metallic element means
respectively carrying said first and second contact means in facing
relation for displacement thereby into and out of engagement with
each other; and a resistive member mounted in series circuit with
said contact means and said resistive heating element means and
positioned in proximity with a side of said first bi-metallic
element means opposite to the side thereof facing said second
bi-metallic element means, so that the displacement of said first
contact means by said first bi-metallic element means is at least
principally in response to the heat generated by said resistive
member and the displacement of said second contact means by said
second bi-metallic element means is at least principally in
response to the temperature at said second region.
3. In combination, a liquid tank having an internal partition
defining a chamber, liquid within said chamber, resistive heating
element means positioned within said liquid-filled chamber for the
transmission of heat through said liquid and partition to liquid
within the balance of said tank; air-exposed temperature control
means positionable at a location external to said tank for
controlling the temperature at which tank liquid is maintained by
said resistive heating element means; and electrical cable means
extending between said resistive heating element means and said
temperature control means for applying current to said resistive
heating element means, said temperature control means being adapted
to control the current applied to said resistive heating element
means in response to temperature at said location, said temperature
control means including first and second contact means; first and
second bi-metallic element means respectively carrying said first
and second contact means in facing relation for displacement
thereby into and out of engagement with each other; and a resistive
member mounted in series circuit with said contact means and said
resistive heating element means and positioned in proximity with a
side of said first bi-metallic element means opposite to the side
thereof facing said second bi-metallic element means, so that the
displacement of said first contact means by said first bi-metallic
element means is at least principally in response to the heat
generated by said resistive member and the displacement of said
second contact means by said second bi-metallic element means is at
least principally in response to the temperature at said second
region.
4. The combination of claim 3 including means in said chamber wall
opening for providing a water-tight seal between said chamber wall
and said electrical cable means.
5. An aquarium-tank heating system, comprising a resistive
water-heating element of relatively large radiation-surface area
and adapted for continuous water-immersion in an aquarium tank,
temperature-control means adapted for ambient-air exposure adjacent
and external to the tank for controlling the temperature at which
tank water is maintained by said resistive water-heating element;
and electrical cable means including a connection extending between
said resistive water-heating element and said temperature-control
means for supplying current to said resistive water-heating element
means, said temperature-control means including a thermostatic
switch and being adapted to control current applied to said
resistive water-heating element means in response to ambient-air
temperature and the amount of energy applied to said resistive
heating element means; said temperature-control means including a
local thermostat-heater element in heat-radiating proximity to said
thermostatic switch to the substantial exclusion of tank water, and
both said heater elements being connected for coordinated and
concurrent energizing and de-energizing by said switch.
6. An aquarium-tank heating system, comprising a resistive
water-heater element of relatively large radiation-surface area and
adapted for continuous water immersion in an aquarium tank, and an
electric-power supply connection to said water-heater element and
including a thermostat-control device adapted for ambient-air
exposure external to the tank; said control device including an
adjustable thermostatic switch connected for on-off control of
electric energy supplied to said water-heater element, a
thermostat-heater element in heat-radiating proximity to said
thermostatic switch, both said heater elements being connected for
coordinated and concurrent energizing and de-energizing, and
housing means for the switch and heater element of said control
device, said housing means being adapted for continuous
external-area exposure to ambient air, whereby energy supplied to
said water-heater element is on a duty-cycle basis wherein average
water-heating energy matches average tank-heat radiation to local
air for a predetermined water temperature in relation to
ambient-air temperature and in spite of changes in ambient-air
temperature.
7. A heating system as recited in claim 6, wherein said
water-heater element is in the form of an essentially flat,
flexible sheet, resistive electrical conductor means being
distributed substantially over the plane defined by said sheet.
8. A heating system as recited in claim 6, in which said
water-heater element is enclosed by electrical insulating material,
and including air-conducting tubes enclosed within said waterproof
insulating material and having at least one inlet and one outlet
opening projecting outside of said material.
9. A heating system as recited in claim 6, in which said
water-heater element is enclosed by electrical insulating material,
and wherein said resistive heating element means is formed in the
shape of a rock having said resistive electrical conductor means
dustributed over the region of at least a portion of the surface
thereof enclosed within said waterproof insulating material.
10. A heating device as recited in claim 6, in which said
water-heater element is enclosed by electrical insulating material,
and wherein said waterproof insulating material is molded to
encapsulate said resistive electrical conductor means and said
electrical cable means as a unit.
11. The combination of the heating device of claim 7 and a fish
tank, and sand or gravel on the bottom of said fish tank, said
sheet-shaped resistive heating element means being positioned
beneath said sand or gravel.
Description
BACKGROUND OF THE INVENTION
This invention is directed to improved heating devices, and in
particular, to heating devices suitable for heating confined
regions such as fish tanks, terrariums, film development tanks and
the like.
In the art, heating devices for fish tanks and film developing
tanks have generally consisted of resistive heating devices
immersed in the tank and controlled by a thermocouple control
likewise immersed in the liquid. This arrangement has proved both
expensive, and inefficient. The system required substantial
variations in the temperature of the liquid for operation.
Frequently, such temperature variations are caused by variations in
the ambient temperature but the prior art temperature control
arrangements respond to the effect of the ambient temperature
changes, rather than directly to ambient temperature changes. By
providing a temperature control device responsive to ambient
conditions and to the energy applied to the resistive heating
element, the foregoing deficiencies in the prior art are
avoided.
SUMMARY OF THE INVENTION
Generally speaking, in accordance with the invention, a heating
device is provided having resistive heating element means for
heating a first region, temperature control means positionable in a
second region spaced from said first region for controlling the
temperature at which said first region is maintained, and
electrical cable means extending between the resistive heating
element means and temperature control means. The temperature
control means is adapted to control the current applied to the
resistive heating element means in response to ambient temperature
and energy applied to said resistive heating element means. The
temperature control means may include a pair of contact means
positioned for selective engagement, at least one of the contact
means being mounted on a bimetallic element, and a resistive member
mounted in series circuit with said contact means and said
resistive heating element means and in proximity with said
bimetallic element so that the opening and closing of said contact
means by the displacement of said bimetallic element means is in
response to the combined effect of ambient temperature at said
second region and the heat generated by said resistive member.
Manual adjustment means may be provided for selectively positioning
one of the contact means relative to the other for selecting the
temperature at which the first region is maintained. The other of
said contact means may be mounted on a further bimetallic
element.
The resistive heating element means may consist of a length of
resistive electrical conductor means distributed over an area and
enclosed by a waterproof insulating material. The length of
resistive electrical conductor may be disposed substantially in a
plane to define, together with said waterproof insulating material
a flexible sheet. In a fish tank, said sheet may be received
beneath the sand or gravel on the bottom of the tank. Said
insulating waterproof material may also receive air-conducting
tubes having an outlet end projecting therefrom, and an inlet
coupled by a further air-conducting tube to a source of air under
pressure.
In another embodiment, said length of resistive electrical
conductor means is distributed in the region of the surface of a
rock-shaped member, the surface of said rock-shape member being
defined by said waterproof, insulating material. In still another
embodiment, a liquid tank is provided with an inner partition
defining a chamber and positioned so that at least a portion of
said partition is engaged by the liquid in the balance of said
tank, said resistive heating element means being received within
said chamber, said chamber being formed with an aperture in a wall
thereof for the passage of said electrical cable means
therethrough. Said aperture may be formed with means for providing
a water tight seal with said electrical cable means.
The heating device in accordance with the invention may be utilized
in fish tanks, terrariums, film developing tanks and the like. Said
temperature control means may be mounted in a housing carrying lamp
means connected in series with said electrical cable means to
provide a visual indication of the application of current through
said resistive heating element, and a temperature indicating means
operatively coupled to a temperature measuring means positioned in
said first region for detecting the temperature at said first
region for display on said temperature indicating means.
Accordingly, it is an object of this invention to provide an
improved heating device for controlling energy input to a resistive
heating element through response to ambient temperature and energy
applied to said resistive heating element means.
A further object of the invention is to provide an improved heating
device including a flat flexible sheet-shaped resistive heating
element, which is waterproof, for positioning in a liquid tank.
Still another object of the invention is to provide an improved
fish tank and terrarium heater capable of positioning beneath the
gravel in a fish tank or terrarium.
A further object of the invention is to provide an improved fish
tank heater shaped as a rock.
Still a further object of the invention is to provide an improved
fish tank heater incorporating air-flow passages for the aeration
of the water in a fish tank.
Another object of the invention is to provide an improved film
development tank heater.
still other objects and advantages of the invention will in part be
obvious and will in part be apparent from the specification and
drawings.
The invention accordingly comprises the features of construction,
combinations of elements, and arrangement of parts which will be
exemplified in the constructions hereinafter after set forth, and
the scope of the invention will be indicated in the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
For a fuller understanding of the invention, reference is had to
the following description taken in connection with the accompanying
drawings, in which:
FIG. 1 is a perspective view of a heating device in accordance with
the invention mounted on a fish tank;
FIG. 2 is a sectional view taken along lines 2--2 of FIG. 1;
FIG. 3 is a sectional view taken along lines 3--3 of FIG. 2;
FIGS. 4 and 5 are perspective views of two partially assembled
embodiments of the resistive heating element means in accordance
with the invention;
FIG. 6 is a perspective view of a further embodiment of a heating
device incorporating air passages in accordance with the invention,
mounted on a fish tank;
FIG. 7 is a sectional view taken along lines 7--7 of FIG. 6;
FIG. 8 is a perspective view of still another embodiment of the
heating device in accordance with the invention mounted in
conjunction with a fish tank;
FIG. 9 is a sectional view taken along lines 9--9 of FIG. 8;
FIG. 10 is a fragmentary sectional view of a further embodiment of
a fish tank incorporating the heating device in accordance with the
invention; and
FIG. 11 is a sectional view of the heating device in accordance
with the invention mounted on a film developing tank.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring first to FIG. 1, a fish tank 10 is depicted having a
resistive heating element 12 mounted on the bottom 14 of said tank
beneath a layer of sand or gravel 16 shown broken away in FIG. 1.
An electrical cable 18 interconnects resistive heating element 12
in a temperature control device 20. Said temperature control device
is mounted on the lip of a side wall 22 of fish tank 10 by means of
a clip 24 formed integral with housing 26 of temperature control 20
and defining a channel 28 dimensioned to receive the lip of side
wall 22 of fish tank 10 (FIG. 3).
Power for the resistive heating element is obtained through
electrical cable 30 which interconnects temperature control 20 and
a conventional plug 32.
The resistive heating element 12 is depicted as being in the form
of a flexible sheet. Heat is produced by the passage of electrical
current through a resistive conductor. Two embodiments of the
resistive heating element 12' and 12" are respectively depicted in
FIGS. 4 and 5. In both embodiments, a length of resistive
electrical conductor is distributed over an area to define a
heating array. In the embodiment of FIG. 4, the length of resistive
electrical conductor defined by a resistive wire 34 is connected at
its ends 36 to cable 18. Wire 34 may be resistance wire, woven wire
or the like. In the case of the embodiment of FIG. 5, the resistive
electrical conductor is formed by a foil 38 which may be etched or
die cut and electrically connected at its end 40 to cable 18. The
arrays defined by resistive wire 34 and foil 38 are each enclosed
between sheets of a suitable waterproof material 42 by a laminating
and bonding technique adapted to insure a waterproof seal along the
periphery olf the sheets 42 and the maintenance of the respective
arrays in position. In place of the laminating technique
illustrated in FIGS. 4 and 5, the sheet may be molded, in which
case the insulation for cable 18 may be simultaneously molded with
the molding of sheet 12 so as to avoid a seam or joint at the
interface between cable 18 and sheet 12 at which leakage may occur.
A wide range of materials may be utilized in forming the sheet
including neoprene, silicone rubber, flexible fiber glass, nylon,
natural rubber, synthetic rubber and plastic materials. One plastic
material found to be particularly suitable for molding and
encapsulating the array formed by wire 34 or foil 38 is
polyamidinide.
Temperature control device 20 is more particularly depicted in
FIGS. 2 and 3. The principal elements of temperature control device
20 are mounted within housing 26 by means of a support post 44
secured to said housing. Mounted on said post and separated from
housing 26 by an insulating spacer 46 is support plate 48. A
pin-shaped insulating spacer 50 is mounted on the end of support
plate 48 spaced from post 44. Mounted on post 44 adjacent support
plate 48 is one end 54 of a resistive member 52 such as a nichrome
strip which is characterized by the fact that it is heated by the
passage of current therethrough in proportion to the amount of the
current passing therethrough. Said one end 54 of resistive member
52 is mounted intermediate support plate 48 and electrical contact
member 56 so as to be electrically connected to said electrical
contact member. The other end 58 of resistive member 52 is mounted
on post 44 separated from electrical contact member 56 by
insulating spacer 60. A first bimetallic strip 62 is mounted on
post 44 adjacent to and in electrical connection with end 58 of
resistive element 52. The central portion 64 of resistive member 52
is positioned in proximity to bimetallic strip 62 so that the heat
generated by said resistive member is applied to said first
bimetallic strip. A second bimetallic strip 66 is mounted on post
44 separated from said first bimetallic strip by an insulating
spacer 68. A second electrical contact member 70 is mounted on post
44 adjacent to and electrically engaging second bimetallic strip
66, an adjustment support plate 72 being mounted on said post
separated from the second contact member 70 by an insulating spacer
74. A first contact 76 is mounted on first bimetallic strip 62 in
facing relation to a second contact 78 mounted on second bimetallic
strip 66. The end 80 of second bimetallic strip 66 is engaged by
insulating pin 50. Second bimetallic strip 66 is formed with an
aperture 82 (FIG. 2) therethrough in registration with an inclined
region 84 on first bimetallic strip 62 and with a threaded aperture
86 in adjustment support plate 72. An adjusting shaft 88 is mounted
on adjustment support plate 72 by a threaded portion 90 thereof
received within threaded aperture 86. An insulating pin 92 projects
from the end of adjusting shaft 88 through aperture 82 in second
bimetallic strip 66 to engage the inclined portion 84 of said first
bimetallic strip. The extent of rotation of adjusting shaft 88 is
limited by means of a stopper member 94 having a pair of laterally
extending arms 96 which engage against an upwardly projecting post
98 mounted on adjustment support plate 72 at two rotational
positions of shaft 88. Adjusting shaft 88 projects through an
opening 100 in housing 26 and is provided with a knob 102 on the
exterior of said housing. Electrical cable 18 is connected between
second contact member 70 and a connecting point defined by
insulating cap 104. Cable 30, connected to the source of power, is
connected between said connecting point and first contact member 56
to define a series circuit passing from cable 30 to first contact
member 56, through resistive member 52, through first bimetallic
strip 62, through first and second contacts 76 and 78 (if closed),
through second bimetallic strip 66, through second contact member
70, through cable 18 to the resistive heating element 12 and back
to cable 30. A lamp 106 is mounted in an aperture 108 in housing 26
and electrically connected by leads 110 and 112 to second contact
member 70 and the connecting point defined by insulating cap 104
respectively to provide a visual indication of the closing of the
above-described series circuit due to the closing of contacts 76
and 78.
Temperature control device 20 is used as follows. Assuming the user
wishes to bring water temperature of a setting of 80.degree. within
the tank and maintain it at that temperature while the room
temperature or ambient temperature is 72.degree.. The top surface
of housing 26 in registration with knob 102 is marked with scale
markings 114 (FIG. 1) for the selective positioning of knob 102.
The user turns the heating device on by rotating the control knob
past the position at which light 106 is lit, indicating the
engagement of first and second contact 76, 78. The electric circuit
is closed, causing current to be applied to the resistive
electrical conductor of resistive heating element 12 to begin
heating the water. This current is also passing through resistive
member 52 causing said resistive member to likewise heat up, which
heat causes first bimetallic strip 62 to distort so as to displace
first contact 76 away from second contact 78 to open the circuit.
Such distortion takes a finite period of time during which the
water is heated. At the initial setting, the contacts will not
normally open before the water temperature reaches the desired
level, in this example 80.degree.. A thermometer is used to check
the temperature in the tank and when the temperature reaches
80.degree., knob 102 is turned until light 106 is turned off,
indicating the opening of contacts 76 and 78. The heating device is
now set to maintain the tank at 80.degree..
As the resistive member 52 cools, the first bimetallic strip
straightens until contacts 76 and 78 close to start the cycle of
the heater again. After sufficient energy is applied to the
resistive heating element 12 as indicated by the heating of
resistive member 52, first bimetallic element 62 distorts
sufficiently to open contacts 76 and 78. The device will continue
to cycle a certain number of times each day to maintain the desired
temperature. If a change in the room temperature occurs or if the
humidity in the room changes, bimetallic strips 62 and 66 will
change their respective shapes to compensate for the changes in
ambient conditions to cause the heater to cycle more or less times
as required to maintain the temperature in the tank at the desired
level. In this manner, the device responds to changes in ambient
temperature before such changes can adversely effect the
temperature of the liquid in the tank.
The formation of resistive heating element 12 as a flexible sheet
and the positioning of said flexible sheet beneath the sand and
gravel of the tank is particularly convenient since an otherwise
unsightly heater is out of view, and, in addition, effective heat
transfer between the sheet and the liquid in the tank can be
achieved over a relatively large area. Further, the positioning of
the heating element beneath the gravel causes certain waste
particles to be freed from the gravel and to rise to the surface
for easy removal.
Frequently, it is desired to provide a source of air under pressure
to a fish tank for increasing the oxygen content of the water. For
this purpose, the resistive heating element may be formed with
air-conducting tubes as shown in the embodiment of FIG. 1. Like
reference numerals are applied to elements in FIG. 6 corresponding
to like elements in FIG. 1. In place of resistive heating element
12, resistive heating element 120 is provided having an array
formed from resistive electrical conductor 122 encapsulated in a
waterproof plastic material 124 (FIG. 7). In addition to the
resistive array, an interconnected array of air-conducting tubes
126 is likewise encapsulated within plastic material 124. The array
of air-conducting tubes is provided with three upwardly projecting
outlets 128 positioned and dimensioned to project through and above
the level of the gravel or sand 16 on the bottom of tank 10. An
inlet tube 130 interconnects an air pump 132 mounted on the side
wall of tank 10 and the air-conducting tubes 126 within the sheet
120. In all other respects the heating device of FIG. 6 functions
in the same manner as the device of FIG. 1.
Still another embodiment is depicted in FIGS. 8 and 9 wherein the
resistive heating device is not in the form of a sheet, as depicted
in FIG. 1, but rather, is in the form of a simulated rock 134 on
the bottom of tank 136. As more particularly shown in FIG. 9, said
simulated rock is formed with a core 138 having an encapsulated
array of a resistive electrical conductor 140 secured to the
surface thereof and electrically connected to cable 142. The
encapsulating material 144 would be waterproof and adapted to
protect the resistive electrical conductor. A temperature control
device such as was described above would be mounted within housing
145 and electrically connected to cable 142 and cable 146, which in
turn is connected to plug 148. The temperature control device would
be operated by the manipulation of knob 150, light 152 being
provided as an indication of the operation of the heating device.
Housing 145 would be mounted on a wall 154 above tank 136. Further,
the embodiment of FIG. 8 is provided with a temperature sensor 156
coupled by cable 158 to a temperature dial 160 mounted on housing
145. By this means, a continuous reading of actual tank temperature
is provided although the temperature control device continues to
function in an automatic mode.
An alternate approach for the positioning and mounting of the
resistive heating element in accordance with the invention is
depicted in FIG. 10, wherein resistive heating element 162 is
received within a special chamber 164 formed in the bottom of tank
166 by means of partition 168. Chamber 164 is filled with liquid so
that the heat generated by resistive heating element 162 is
distributed over the entire bottom of the tank, transmitted through
partition 168, and even applied to the liquid 170 in the main
portion of the tank. One wall of chamber 164 is formed with an
opening 172 which receives a seal member 174 through which cable
176 from resistive heating element 162 extends in water tight
relation.
The heating device in accordance with the invention may be applied
to applications other than fish tanks and terrariums where confined
spaces are to be heated. An example of such a further application
is illustrated in FIG. 10 wherein a film development tank 180 is
depicted. Received within film developing tank 180 are smaller
chemical tanks 182 and 184. The film developing tank 180 is filled
with water 186 which is maintained at the desired temperature by a
resistive heating element 188 in accordance with the invention. The
heated water in the film developing tank 180 in turn maintains the
temperature of the chemicals 190 and 192 in chemical tanks 182 and
184 at the desired temperature. Said chemical tanks are held in
position by brackets (not shown). Resistive heating element 188 is
coupled by cable 194 to a temperature control device in accordance
with the invention mounted within housing 196 mounted above tank
180. The temperature control device is provided with a control knob
198 and indicating lamp 200 as in the above-described embodiments.
In addition, the housing carries a temperature indicating dial 202
coupled to a temperature sensing device 204 through cable 206 and a
mechanical timer 208 for use in the film-developing process. Cable
210 connects plug 212 to the temperature control device within
housing 196.
It will thus be seen that the objects set forth above, and those
made apparent from the preceding description, are efficiently
attained and, since certain changes may be made in the above
constructions without departing from the spirit and scope of the
invention, it is intended that all matter contained in the above
description or shown in the accompanying drawings shall be
interpreted as illustrative and not in a limiting sense.
It is also to be understood that the following claims are intended
to cover all of the generic and specific features of the invention
herein described, and all statements of the scope of the invention
which, as a matter of language, might be said to fall
therebetween.
* * * * *