US3417226A - Temperature responsive apparatus - Google Patents

Description

1968 H. J. THOMISZER TEMPERATURE RESPONSIVE APPARATUS Filed April 19, 1965 United States Patent 3,417,226 TEMPERATURE RESPONSIVE APPARATUS Hubert J. Thomiszer, Skokie, Ill., assignor to Eugene Dietzgen Co., Chicago, Ill., a corporation of Delaware Filed Apr. 19, 1965, Ser. No. 449,095 11 Claims. (Cl. 219-216) ABSTRACT OF THE DISCLOSURE A stationary heat sensor for a traveling heat-containing body comprising a resilient blade of heat-conducting material carrying a heat sensitive element secured in direct heat exchange contact with one side of the blade, so that the moving body may be thermally monitored by stationarily mounting the blade for the sliding engagement of its other side with the body, vertically opposite the sensitive element.

The present invention relates in general to heat sensitive control apparatus, and has more particular reference to means for determining and regulating the operating temperature of a rotary processing drum, such as the sheet conveying and heat treating drum or roller of a thermographic printing machine, in order to assure processing of thermosensitive copying material at a temperature held within a desired relatively small range.

The production of copies of original graphic material, such as typewritten and other written or printed material, sketches, tracings, drawings, photographs, memoranda and the like, or thermosensitive copying material, may be accomplished by exposing the material to the action of heat which, in the interests of uniformity in the resulting copy or print, should be held at a substantially uniform temperature level, so that all prints may be processed at the same temperature, and all parts of the copy material subjected to the same quanta of heat as every other part of the sheet during treatment, the maintenance of isothermic treating conditions being especially important in equipment for continuous print production by carrying the heat sensitive copying material progressively through a heated zone.

An important object of the present invention is to provide improved heat responsive means for determining and controlling, within close limits, the operating temperature of heating apparatus; a further object being to provide an appropriately located thermistor in heat exchange relationship with a heater for processing thermosensitive material to thereby accurately control the temperature at which the material is treated.

Another important object of the present invention is to provide an improved mounting for a thermosensitive detection element to maintain the same continuously in heat exchange relationship with a heated conveying and treating component of sheet processing equipment, the heat sensitive element being connected to control energy supplied to heat the treating component in accordance with the prevailing temperature at which heat is applied upon a sheet being processed; a further object being to provide improved means for supporting a thermistor as a heat responsive element in thermal contact with a heated sheet treating conveyor, the thermistor being controllingly connected with electrical circuitry for controlling the delivery of energizing power to electrically actuated means for heating the sheet treating component.

The foregoing and numerous other important objects, advantages and inherent functions of the invention will become apparent as the same is more fully understood from the following description, which, taken in connection with the accompanying drawings, discloses a preferred embodiment of the invention.

Referring to the drawings:

FIG. 1 is a sectional view taken logitudinally through sheet transporting and treating apparatus;

FIG. 2 is an end view of the apparatus shown in FIG. 1;

FIG. 3 is an enlarged perspective view of a component of the processing apparatus shown in FIG. 2, said component comprising an improved mounting for supporting a heat sensitive detector in heat exchange contact with a sheet conveying and treating element of the processing apparatus;

FIG. 4 is an enlarged sectional view taken substantially along the line 4-4 in FIG. 3; and

FIG. 5 is a diagram of electrical circuitry for connecting the heat sensitive detector for control of the temperature level at which it is desired to maintain the sheet heating and conveying element.

To illustrate the invention, the drawings show processing apparatus 11 for conveying heat sensitive sheet material 13 along a selected path between sheet receiving and sheet delivery stations 15 and 17. The sheet material may comprise a web, as of paper, fabric or other suitable sheeting, containing a heat sensitive composition permitting highly visible, inert and stable images to be produced in the sheet upon exposure to heat. The sensitive coating may comprise any suitable substance having the desired characteristics. Such material, for example, may embody a diazo compound, and an azo dye coupling component, together with a substance capable of producing or permitting a diazo developing reaction when heated at temperatures of the order of say, 300 F. Such d-iazotype material is not only sensitive to heat, but is convertible to stable, colorless condition upon exposure to radiation containing ultraviolet rays, either alone or in combination with other radiation, including visible light.

In making a copy of an original or master having imprinted or otherwise applied thereon graphic marks or characters embodying material capable of absorbing ultraviolet radiation, the sensitized copy sheet may be stacked with the original or master to be copied to form an eX- posure sandwich adapted for exposure of the light sensitive material to ultraviolet rays applied thereto through the original or master to be copied. Latent images corresponding with the graphic markings or characters of the original may thus be produced in the sensitive material as a result of the diazo destroying or inactivating action of the ultraviolet radiation on all portions of the sensitive sheet except such as have been screened by the characters or graphic markings of the original during the exposure interval. The latent images thus formed in the copying sheet may then be stabilized and converted to permanently visible condition by heating the copying sheet at temperatures of the order of 300 F.

The sheet processing apparatus 11 may comprise a pair of relatively movable sheet guiding and moving components 19 and 21, means being provided for heating at least one of the components in order to apply heat to a sheet of material to be treated as the same is transported between the components. To this end, a heater 23 may be provided for heating the component 19'. As shown, the heated component 19 may be formed as a continously turnable cylindrical member, such as a sleeve of aluminum or other suitable heat conducting material, while the component 21 may comprise a strip or web of material embracing and in contact with the peripheral surfaces of the sleeve which forms the component 19. The web forming the component 21 may be anchored at one end on a stationary support or clamp 25, the opposite end of the web being connected with resilient means 26 for snugly and yieldingly pressing the web upon and about the surfaces of the sleeve component 19. The web preferably embraces 3 surfaces of the sleeve subtending an angle of the order of 240.

The cylindrical sleeve member forming the component 19 may be provided with a black coating upon its inner surface to constitute the same as a black body capable of absorbing heat readily from any source disposed within the sleeve, the outer surfaces of the sleeve having any preferred coloration, other than black, in order to promote heat emission outwardly of the sleeve and into any sheet material held upon the outer surfaces thereof, as the same is turned within the web or belt element 21.

The belt element 21 may comprise any suitable heat resisting web material, such as a fiberglass fabric layer 27 impregnated with Teflon plastic or similar synthetic plastic providing a heat resistant web of adequate strength. Since the surface of a woven fiberglass fabric sheet is not entirely smooth even when impregnated with plastic, it is desirable to provide a lining layer 29 of pure Teflon or like plastic material in position overlying the surface of the woven fabric layer 27 which faces inwardly upon the sleeve 19, said lining layer having thickness of the order of two one-thousandths (0.002) of an inch. The lining 29 may be formed on and adhered to the layer 27 as an integral part thereof, or it may be formed as a separate element, in which case one end of the lining may be securely anchored in the clamp 25 together with the layer 27, while the opposite end of the lining layer 29 may extend to and float unanchored at the sheet delivery station 17. Teflon is a good heat reservoir material because of its low thermal conductivity. Accordingly, it is well suited for use in apparatus for transporting sheet material while exposing the same to the action of heat.

The developing apparatus may comprise a stationary support structure embodying a pair of spaced apart end plates 31 forming bearing supports. These end plates may be made of Bakelite or Formica, with glass or asbestos as a filler material, and the same may be mounted on a suitable support base 33, in any suitable, preferred or convenient fashion. The end plates 31 may each be provided with a circular opening 35 sized for the turnable reception of bearing sleeves 37 secured upon and at the opposite ends of the sheet transporting sleeve 19, to thereby support the sleeve turnably on the end plates 31. Heat insulating shields in the form of plates 39, of Fiberg-las, Transite or other heat resistant material, may be secured to the opposite ends of the sleeve 19, as by means of fastening studs 41 penetrating said plates and inwardly turned peripheral mounting flanges 43 formed on the opposite ends of the sleeve 19.

In alinement with the axis of the sleeve 19, the end plates 39 may be formed with central perforations 45 sized to permit the insertion therethrough of the heater 23, which preferably comprises an elongated tubular infrared ray lamp 47 of conventional construction, the same conveniently comprising a tubular quartz lamp of the sort identified as No. T3, manufactured by General Electric Company and having a color temperature of 2400 K. The opposite ends of the infrared ray lamp 47 may extend outwardly of the heat shields 39 and may carry connection electrodes 49 for reception in connection clips 51. These clips may be carried upon brackets 53 mounted upon the base 33 in position to support the infrared ray lamp 47 coaxially within the sleeve 19. The lamp mounting clips 51 may be electrically connected in external lamp energizing circuitry 55, of the sort shown in FIG. 5.

While and so long as the lamp 47 is appropriately energized for operation as an infrared ray emitter, the resulting radiation will be applied upon the inner black coated surface of the sleeve 19', which consequently will absorb substantially all of the radiation emitted by the lamp. Such absorbed radiation will heat the sleeve 19 to the temperature required for the development of the sensitive copying material 13. As a consequence, visible images may be developed in the material as it is transported in contact with the heated sleeve 19 between the sheet receiving and sheet delivery stations 15 and 17.

Any suitable means may be provided for turning the sleeve within the embracing web or belt 21, preferably at an adjustable, uniform rate of speed, in order to transport the sheet material between the receiving and delivery stations. As shown, a sprocket wheel 57 may be secured upon and outwardly of a heat shield 39, at one end of the sleeve 19, and a chain 59 may be employed to drivingly connect the sprocket Wheel with a driving pinion 61. The pinion in turn may be drivingly connected with a suitable motor, such as an electrical motor 63, which may be supported on and secured to the base 33. Reduction gearing may be interposed between the pinion 61 and the motor to turn the sleeve 19 at appropriate speed. Suitable motor control means of conventional character may, of course, be provided for starting and stopping the motor and for regulating its speed in order to determine the rate of travel of sheet material around the sleeve 19, between the receiving and delivery stations 15 and 17.

It will be seen that rotation of the sleeve 19 within the web or belt 21 will serve to transport sheet material around the sleeve from the receiving station 15 to the delivery station 17. In order to aid in guiding the sheet at said stations, a preferably formed sheet metal housing or cover 65 may be mounted on and between the end plates 31 in position enclosing the portions of the sleeve which extend between the delivery station and the receiving station and which are not covered by the web 21. The housing thus may serve to enclose the otherwise exposed areas of the sleeve and tend to minimize heat loss to circumambient atmosphere. The housing has lower and upper walls 67, 69, respectively extending at the receiving and delivery stations to aid in guiding the sheet as it enters and is discharged from between the sleeve 19 and web or belt 21. The upper wall 69 of the cover may carry a blade 71 defining one side of the delivery station, said blade having an edge adapted to ride on the surface of the sleeve 19 in order to separate the sheet material being treated from the sleeve and guide it onto and over the upper wall 69, to thereby eject treated sheets from the apparatus at the delivery station.

An important feature of the present invention resides in the provision of heat sensitive means 73 responsive to the temperature at which heat is applied to the copying sheet by the sleeve 19, and hence adapted to serve as a monitor to control the supply of operating energy to the heating lamp 23 to thereby maintain within close limits the operating temperature at which heat is applied to the sensitive sheet material 13.

To this end, the heat sensitive means 73 preferably comprises a small lump or pellet of material forming a thermistor 75 preferably configurated as a hemispherical body having a flat surface 77 formed on one side. The thermistor is preferably mounted on a resilient support blade 79, with the flat surface 77 of the thermistor in facing engagement with one side of the blade. The support blade may conveniently be made of blue tempered spring steel having thickness of the order of a few thousandths of an inch, to provide a resilient, somewhat flexible support member for the thermistor. The blade 79 may have triangular configuration and may be formed with a triangular opening therethrough, said triangular blade having a preferably integral mounting flange 81 extending along its basal edge, the thermistor 75 being secured to the rear side of the blade, at its apexial corner 83 remote from its basal edge. The thermistor may be secured in situ on the blade by means of a blob of epoxy resin cement 85 or other suitable heat resistant mounting means.

Any suitable or preferred means may be employed for mounting the blade 79 in the apparatus 11 in position to present the front side of the resilient blade, at its apexial corner 83, in wiping engagement with the outer sheet engaging surface of the sleeve 19, as it passes behind the cover 65 from the sheet delivery station 17 to the sheet receiving station 15. The thermistor 75 will thus be placed in intimate heat exchange relation with respect to the heated treating sleeve, since the thermistor is in thermal contact with the back side of the thin, metal carrying blade, directly opposite and in alinement with the front portion of the blade that is in wiping contact with the heated sleeve. The blade preferably has thickness of the order of 0.005 of an inch, and consequently is so thin that heat may pass therethrough, substantially instantly, between the sleeve and the thermistor. It will thus be seen that the thermistor will be disposed in position exposed to the same heat source that applies heat to a sheet of sensitive material 13, as the same is carried by and in contact with the sleeve 19 and between it and the lining layer 29, from the sheet receiving station to the sheet delivery station 17. Obviously, any change in the temperature at which heat is applied to the sheet being processed by the sleeve will be sensed substantially instantly by the blade mounted thermistor.

The thermistor carrying blade may be supported on the housing or cover 65. To this end, the wall 69 of the cover may be provided with a pair of spaced, inwardly extending pedestals 87 to threadingly receive a pair of fastening screws 89 for clamping a blade mounting panel 91 of insulating material on the inner side of the cover wall 69, the panel having holes 93 to accommodate the screws. The flange 81, at the base of the blade 79 may be formed with a pair of spaced slots 95 for receiving a pair of clamp screws 97 that are threaded in openings formed in the panel 91. The blade 79 and its mounting flange 81 are mutually inclined at an angle such that when the flange is secured on the panel 91, the blade will extend in position to press its apexial thermistor carrying corner yieldingly upon the surface of the sleeve 19, through the inherent resilience of the legs of the triangular blade, the central opening of which extends between and to some extent determines the desired resilience of the legs. The thermistor may be electrically connected with the electrical circuitry 55 by a pair of conductors 99, one of which may have an end embedded in and electrically connected with the termistor, while the other is electrically connected with the fiat face 77 of the thermistor through the blade 79 and its mounting flange 81 with which the said other conductor is connected by means of one of the clamp screws 97.

As shown more particularly in FIG. 5 of the drawings, the heater element 47 may be energized from any suitable, preferred or convenient electrical power source 101 through an energizing circuit including supply conductors 103, disconnect switch means 105 and a relay switch 107 operable under the control of a solenoid 109 to selectively permit and prevent the delivery of operating energy to the heating element 47. Conventional amplifying means 111 may be provided for selectively actuating the solenoid 109 of the relay switch under the control of the heat responsive thermistor 75, said amplifying means conveniently comprising a device of the sort manufactured by Fenwal Inc. as its Model No. 535 temperature controller, such amplifier being energized by electrical power supplied from the source 101, through the disconnect switch means 105, and having the thermistor 75 controllingly connected therewith as by means of the leads 99. The actuating solenoid 109 of the relay switch 107 may be energized from the power source 101 under the control of the amplifier 111, as indicated by the connection of the solenoid in series with the output side of the amplifier across the conductors 103; and the operating characteristics of the amplifier 111 may be varied by adjusting ganged potentiometers 113 electrically connected therewith, in order to cause the switch 107 to open and close at any desired temperature level, within the operating range of the amplifier apparatus, as determined by the thermistor.

The control apparatus of the present invention makes it possible to maintain, precisely and accurately, a desired temperature level of heat applied for the processing of sensitive material as it is carried between the inlet and delivery stations 15 and 17. Apparatus of the sort herein disclosed permits the temperature level to be controlled well within a 5 range above and below a precise desired temperature level, and furthermore provides an extremely rapid response when coupled with an infrared lamp as a heat source within a thin walled metal heating cylinder. The mounting of the thermistor upon the support blade 79 in the manner described enables the sensitivity of the thermistor to be realized at optimum efficiency in determining the temperature at which heat is applied upon the sheet being processed. Since the thermistor is mounted in direct contact with the very thin metal mounting blade 79, which in turn directly engages the sheet heating sleeve, it will be obvious that an extremely rapid, substantially instantaneous response to changes in sheet treating temperature will be realized.

The foregoing thermistor arrangement also assures minimal thermal lag from the moment the thermistor signals for an increase or a decrease in heat required for optimum development. Since the time constant for the thermistor mounted in place in the manner disclosed is somewhat less than one-tenth (0.1) of a second, it is desirable that the time constant for the mechanical heat transfer system consisting of infrared lamp and aluminum cylinder be of the same order of magnitude. Such a time constant is attained by employment of an infrared ray source 47 of the character described, in conjunction with a slave 19 comprising a thin walled aluminum cylinder having thickness of the order of thirty-five onethousandths (0.035) of an inch. The time constant of the ray source 47 is approximately one-twelfth (0.083) of a second, and the time constant for the aluminum cylinder is approximately the same value. As a consequence, the total time constant for the transfer of heat from the ray source to the sheet material being treated is of the order of one-quarter (0.25) of a second. This circumstance, coupled with the small time constant of a thermistor mounted in the manner described, has permitted the use of a cylinder having a diameter of the order of three inches while providing for proper development of the sensitive material at acceptable linear speeds of the order of seven to fifteen feet per minute.

The use of infrared radiation together with the thin walled aluminum cylinder of small diameter, in conjunction with a thermistor having an extremely small time response constant, because of the manner of mounting it, has permitted accurate temperature control on a practical basis, thereby making possible the heat development of diazotype sensitive material as a continuous operation in apparatus that is sufiiciently compact to allow for its convenient use as a piece of table top office equipment.

It is thought that the invention and its numerous attendant advantages will be fully understood from the foregoing description, and it is obvious that numerous changes may be made in the form, construction and arrangement of the several parts without departing from the spirit or scope of the invention, or sacrificing any of its attendant advantages, the form herein disclosed being a preferred embodiment for the purpose of illustrating the invention.

The invention is hereby claimed as follows:

1. A heat sensor comprising a resilient blade of heat conducting material of triangular marginal configuration to provide an apexial corner remote from the basal edge of said blade, and a thermally sensitive element secured on and in direct heat exchange contact with one side of said blade at said corner, whereby a heat containing body may be thermally monitored by engaging the other side of the blade directly upon the heat containing body, at said corner.

2. A heat sensor as set forth in claim 1, wherein the blade comprises sheet metal having thickness of the order of five-thousandths of an inch.

3. A heat sensor as set forth in claim 2, wherein the blade comprises a resilient sheet of spring steel.

4. A heat sensor as set forth in claim 1, wherein the thermally sensitive element comprises a lump of material having a flat face of appreciable area in facing contact with the blade at said corner,

5. A heat sensor as set forth in claim 1, wherein the thermally sensitive element is secured on the blade by means of heat resisting epoxy resin cement.

6. A heat sensor as set forth in claim 1, wherein the thermally sensitive element comprises a thermistor.

7. A heat sensor as set forth in claim 1, wherein the blade has a mounting flange along said basal edge thereof and inclined at an angle with respect to the blade to carry the same at a desired inclination on a support.

8. A heat sensor comprising a resilient blade of heat conducting material having a mounting flange secured at and along an edge thereof and inclined at an angle with respect to the blade to carry the same at a desired inclination on a support, a thermally sensitive element secured on and in direct heat exchange contact with one side of said blade, whereby a heat containing body may be thermally monitored by engaging the other side of the blade directly upon the heat containing body, an insulator forming a support for the blade, means for securing the blade mounting flange on said insulator, and means to electrically connect the blade and thermally sensitive element in external electrical circuitry.

9. A heat sensor for use in thermally monitoring a movable heat containing body component of apparatus to be controlled comprising a resilient metal mounting blade of heat conducting material of triangular marginal configuration with a triangular opening therein to provide an apexial corner remote from the basal edge of said blade, a thermally responsive element secured on and in direct electrical and thermal contact with the blade, on one side thereof, an electrically insulating mounting, and anchor means for securing the basal edge of said blade on the mounting and the insulating mounting in the apparatus to be controlled in position presenting the other side of the blade wipingly on the surface of the movable heat containing body.

10. A heat sensor for use in thermally monitoring a movable heat containing body component of apparatus to be controlled comprising a resilient metal mounting blade, a thermally responsive element secured on and in direct electrical and thermal contact with the blade, on one side thereof, an electrically insulating mounting, a flange secured on the blade and extending along a marginal edge thereof to form anchor means for securing the blade on the mounting, and means for securing the insulating mounting in the apparatus to be controlled in position presenting the other side of the blade wipingly on the surface of the movable heat containing body. 11. A heat sensor for use in thermally monitoring a movable heat containing body component of apparatus to be controlled comprising a resilient metal mounting blade, a thermally responsive element secured on and in direct electrical and thermal contact with the blade, on one side thereof, an electrically insulating mounting, anchor means for securing the blade on the mounting and the insulating mounting in the apparatus to be controlled in position presenting the other side of the blade wipingly on the surface of the movable heat containing body, and means for electrically connecting the blade and thermally responsive element in external electrical circuitry.

References Cited UNITED STATES PATENTS 2,480,703 8/1949 Bradner et al. 73351 2,627,182 2/1953 Quereau et al 73351 3,178,112 4/1965 Rudd 73-351 X 3,279,956 10/1966 Ekstrom Jr 73-351 X 2,414,792 1/1947 Becker 33822 X 2,739,218 3/1956 Wennerlund 219-469 2,788,587 4/1957 Dsenis 219-469 X 2,966,646 12/1960 Baasch 338--22 3,012,141 12/1961 Thomiszer 219342 3,163,841 12/1964 Willett 219-345 X 3,189,729 6/1965 Lusebrink 219-469 3,219,794 11/1965 Mindell et al. 2192l6 3,243,572 3/1966 Vogt et al. 33822 X RICHARD M. WOOD, Primary Examiner.

C. L. ALBRITTON, Assistant Examiner.

U.S. c1. X.R.

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