US3128379A

US3128379A - Thermocopying machine with temperature and speed correlating means

Info

Publication number: US3128379A
Application number: US68831A
Authority: US
Inventors: Raymond M Cisek; Paul A Enblom; Robert J Kline
Original assignee: Minnesota Mining and Manufacturing Co
Current assignee: 3M Co
Priority date: 1960-11-14
Filing date: 1960-11-14
Publication date: 1964-04-07
Anticipated expiration: 1981-04-07

Description

April 7, 1964 c s ETAL 3,128,379

THERMOCOPYING MACHINE WITH TEMPERATURE AND SPEED CORRELATING MEANS Filed Nov. 14, 1960 POBERTJ A: INE PAY/Mafia M C/SEK PA L/L A E/VBL 0M United States Patent a corporation of Delaware Filed Nov. 14, 1960, Ser. No. 68,831 6 Claims. (Cl. 250-65) This invention relates to apparatus for the rapid automatic thermographic reproduction on heat sensitive copypaper of graphic original pages in the nature of printed or typewritten reports, correspondence, drawings, etc.; this invention has particular reference to a method and means for correlating the rate of advance of the graphic original and copy-paper through the apparatus with the temperature in the copy exposure zone of the apparatus.

The reproduction of graphic originals by methods involving brief, intense irradiation of a composite of a graphic original in heat-conductive, pressure-contact with a heat-sensitive copy-paper has been described in Miller Patent 2,740,896. Suitable apparatus for such reproduction is described in Kuhrmeyer et al. Patent No. 2,891,- 165 and in Miller Patent No. 2,740,895.

The present invention provides for further improvement in the art of thermocopying and in particular provides means enabling the machine operator to more accurately and reproducibly correlate the rate of advance of the composite of graphic original and heat sensitive copypaper through a machine such as that described in Kuhrmeyer et al. Patent No. 2,891,165 with the temperature in the copy exposure zone of the machine.

In the utilization of thermocopying apparatus of the type set forth hereinbefore prior to this invention, experimentation by the operator of the apparatus or machine was sometimes necessary to properly correlate the speed of passage of the graphic original-copy-sheet composite through the machine with the machine temperature in the exposure zone of the machine. Such correlation is obtained by adjustment of the speed control dial of the machine by the operator after observing the condition of the previously made copy. Speed adjustments with these prior art machines were thus made by observation of the inadequacy of the preceding copy, e.g. too dark or too light. As the internal temperature in the copy exposure zone fluctuates it is desirable that the speed of the composite through the machine be correspondingly varied to achieve the most consistently good quality reproduction of the graphic original on the heat sensitive copy-paper of each exposed composite before the copy is made. However, attempted visually observable means for correlating speed and temperature by presetting the speed in accordance with the temperature prior to the present invention still resulted in frequent departure from optimum exposure conditions because of unpredictable variations in speed control settings from the predetermined speed control-temperature indicating correlations under varying conditions of use of the apparatus and/or with graphic original sheets of different thicknesses, etc.

It is a principal object of this invention to provide the machine operator with a visually observable speed and temperature correlating means which enables the operator to preset the speed of the composite through the machine exposure zone to produce good copies in accordance with a predetermined speed-temperature relationship in a simple and effective manner without first running sample copies and resorting to inspection of such sample copies to make desired speed control adjustments. This novel temperature-speed correlating means enables presetting the machine speed to make good copies before advanc- 3,128,379 Patented Apr. 7, 1964 ing the copy-original composite through the machine and under normal conditions of machine use irrespective of the length of time the machine has been in operation (i.e. whether the machine is cold or hot) and irrespective of variations in the type and thicknesses of the graphic original pages being copied. Other objects and advantages of this invention will become apparent as the description proceeds.

In the practice of the present invention there is incorporated into the thermographic reproduction machine composite advancing means, a reflective surfaced heat insulating roller over which the graphic original-copypaper composite is drawn through the copy exposure zone; this roller coacts with a temperature sensing and indicating means to provide the unique speed-temperature correlating means of this invention. It has been found that this combination of temperature sensing-indicating means and reflective surfaced insulating roller provides a presettable machine speed and temperature correlation means facilitating speed control adjustment by the operator prior to inserting a composite into the machine for reproduction of good copy with an accuracy and freedom from variability not heretofore obtainable.

The invention will now be described in more detail with reference to the accompanying drawing wherein:

FIGURE 1 is a schematic illustration of a thermocopying apparatus useful in the practice of this invention;

FIGURE 2 is a front view of the speed control dial of the thermocopying apparatus;

FIGURE 3 is a cross sectional view through the heat insulating roller of the apparatus; and

FIGURE 4 illustrates modified speed control dial directly correlated with a temperature indicator.

For ease of cross reference, where possible, the numbers utilized to represent various parts of the apparatus herein correspond to the numbers used in the Kuhrmeyer et al. Patent No. 2,891,165.

Referring first to the schematic illustration of FIGURE 1, the apparatus includes a flexible carrier belt 10 supported on a series of revolving drums or

rolls

11, 12, 13, and 15 supported on a suitable frame 14, and corresponds generally to the apparatus illustrated and described in Patent No. 2,891,165, deleting such structure as is not required for an explanation of the present invention. Drum 15 is mounted on the frame 14 (by means not shown) for adjustment to control tension on the belt 10.

The lower drum 13 serves as a driver roller and is driven by propulsion means not shown, which propulsion means is controllable through speed control dial 17 illustrated schematically in FIGURE 1 and in detail in FIG- URE 2.

A tubular line-filament lamp 31 disposed within an open elliptical reflector 32 is located parallel to the central drum or roller 12 with the open face of the reflector closely adjacent the surface of the drum. The filament of the lamp 31 is located along one of the focal lines of the elliptically cross-sectioned reflector, the position of the other focal line falling just in front of the surface of the drum 12. The lamp is actuated by a switch 33, as indicated schematically in FIGURE 1.

Contact levers

34 and 35, attached to the switch 33, cross an entrance channel 36 and an exit channel 37 respectively, the channels being formed between

frame members

38, 39, and 40 of the frame 14 is indicated.

A temperature sensing device 41 is mounted within the machine adjacent to the exposure zone between the lamp 31 and the reflective surfaced insulated roller 12 in such position as to most effectively sense the temperature in the interior of the machine adjacent the copy exposure zone. To be most effective, this temperature sensing means should be placed to remain free of significant conduction from the machine parts but in such a position as to sense radiation and convection effects from machine parts adjacent the exposure zone that have bearing on the temperature in this zone.

Thus, in a copying machine of the type illustrated excellent results have been obtained using a vapor-tension thermometer having a range of temperature response from 30 F. to 220 F., the sensing bulb 41 of which is mounted on the underside of a flat frame portion 14 of the machine overyling the exposure zone, being insulated from this frame portion by an insulating pad 51. Preferably, the sensing bulb is positioned about one quarter of the distance from one end of roller 12 to the other and is so suspended as to register the ambient air temperature immediately adjacent the exposure zone while also registering changes in radiation reflective and convection effects from the roller 12, lamp 31, reflector 32 and the adjacent machine parts. The sensing device should be free of significant conduction heat from any machine parts for best performance. The indicating element 44 (FIG. 2.) or 59 (FIG. 4) operatively connected to the sensing bulb 41 through the medium of a capillary tube or other means is disposed exteriorly of the machine in view of the machine operator.

With reference to FIGURE 2, speed control dial 17 is illustrated as comprising a rotatable outer ring 42, bearing the numbers 1 to the lowest number indicating the slowest speed of the rollers and belt 14) and the highest number indicating the fastest speed of the rollers and belt 19. The speed at which the machine is being operated is indicated by the number of the control ring lined up with the marker 43 on the exterior portion of the frame 14 of the machine. Within the rotatable speed control ring 2 is a speed-temperature scale calibrated to display the optimum speed control setting for various types of heat sensitive copy-paper in accordance with the position of the temperature indicator 44 to enable the operator to select the best operating speed for the machine before inserting the composite.

The calibrated scale illustrated in FIGURE 2 is in the form of a circular panel 45 having a pair of outer and inner concentric

circular scales

46 and 47 imprinted or otherwise placed thereon which scales contain numbers corresponding to the speed control numbers on the rotatable speed control dial 42. Each of the

scales

46 and 47 is calibrated for a different type of heat sensitive copypaper with the numbers thereon corresponding with the speed control ring numbers. The speed best suited to the copy-paper being used at the temperature registered by the temperature sensing device 41 is indicated by the pointer 44.

Any suitable temperature sensing-indicating system can be used. A preferred system comprises a vapor-tension thermometer as previously described. But, thermocouple heat sensors associated with voltmeter or ammeter indicators can be used as can thermistor sensors connected with suitable ammeter or resistance meter indicators; 21 bimetallic element and mechanical linkage to an indicating mechanism can be used, as well as other systems.

The central roller 12 which carries the composite through the exposure area of the machine forms a part of the speed-temperature correlation means. The drum or roller 12 illustrated in FIGURES 3 comprises an aluminum shell or core 50 coated with a plurality of coats of a heat resistant, heat cured, clear lacquer. To the surface of this lacquer layer 49 is applied a thin, vapor deposited coating of essentially pure aluminum (about 99.9%). V Thereafter, a series of further clear lacquer coacts to build up a considerable thickness over the vapor coating are applied. The lacquer coating applied was a heat resistant, transparent, baked enamel lacquer of the alkyl type, being formed from an oil modified alkyd resin containing a melamine-aldehyde curing agent. The lacquer over-layer 49 within which the vapor coating 48 is sandwiched is an excellent heat insulator and is sufflciently resistant to abrasion to protect the aluminum vapor coating against rubbing off. The vapor coating 4d and the insulating layers 49 between which it is sand wiched are greatly exaggerated in size in the illustration of FIGURE 3, there being in fact usually two coatings of lacquer 49 on the core 5t)" prior to applying the vapor coating 48, which coatings serve as a layer on which to anchor the vapor coating with six further lacquer coatings forming the insulating over-layer 49 covering the vapor coat. The vapor coating provides a polished reflective mirror-like aluminum surface.

To provide copies with optimum contrast of the graphic information reproduced thereon at the fastest speeds, the reflective surface of the insulating body or roller should be selected to best reflect the radiations of the heat source, e.g. aluminum, gold, silver, etc. The heat insulating body need just be sutficiently thick to avoid absorption by the roller core of a significant amount of heat so that neither the core of the roller body nor the layer providing the reflective surface will serve as a heat storage reservoir. v

Useful, although short lived, rollers have been made utilizing metal roller drum bodies such as 50 illustrated by simply wrapping these bodies with two or three layers of thin, white, tissue paper, the white surface of the tissue paper apparently providing a sufficiently reflective sur= face to produce good copy, although at slower speeds than with more reflective surfaces, and the interstices between the paper layers and fibers of the paper providing a sufficient insulating blanket to enable proper and accurate speed-temperature correlation unaffected by the kind or thickness of graphic original sheet being copied. These reflective surfaced insulating bodied rollers, unlike uninsulated reflective metal rollers do not necessitate speed changes in the machines due to varying thicknesses of graphic original pages.

The operation of the apparatus is begun by first turning on the machine so that the endless belt 1% moves in the direction of the arrow shown in FIGURE 1. The operator checks the temperature indicator 44 and its position relative to the speed control dial numbers on the calibrating panel 45 for the copy-paper being used and thereafter sets the speed control dial 42 in accordance with the speed indicated by the indicator on the panel 45. Then the operator inserts a composite of the printed, written, or typewritten graphic original sheet of which a copy is desired in contact with a suitable heat sensitive copy-paper and the composite formed by these two sheets is fed into the machine through the entrance channel '36. Contact of the sheet material with the contact lever 34 actuates the switch '33 and the lamp 31. The sheets are drawn between the belt 10 and the drum 12 and through the exposure zone in front of the lamp assembly in which zone they are strongly and briefly irradiated while being held firmly and smoothly together under pressure contact. The sheets then pass out through channel 37 and during this period are in contact with contact lever 1*)5 to continue actuation of the lamp 31 until the composite has passed completely beyond the area of exposure.

As the temperature within the machine changes in the area of exposure, such change is sensed by the sensing device 41 and is indicated on the calibrated dial face 45 by the indicator 44 as the change occurs so that the operator of the machine can adjust the speed of the machine in accordance with the indicator 44 for each composite fed through the machine for copying until the temperature becomes more or less stable within the machine as occurs through sustained operation of the machine.

With this speed-temperature correlating means it has been found that the calibration of machine speed with temperature for various copy-papers holds true regardless of the graphic original page thickness and generally irrespective of the manner of use of the machine, e.g. continuous, sporadic, short period, long period, or other normal use conditions.

In FIGURE 4 there is illustrated a preferred speed control dial '54 directly correlated with a temperature indicator 59 (corresponding to indicator 44 of FIGURE 2) without the necessity for an intervening calibrated scale such as '45 of FIGURE 2. In this embodiment the speed control dial 54 has arranged thereon at circumferentially spaced intervals therearound colored strips or the like, 56, 57 and 58 representing various types of copypaper. Temperature indicator 59, visible through the dial 54 moves in response to temperature variations sensed by sensing device 41.

In operating a thermocopying machine equipped with speed control dial 54, the operator need only glance at the position of pointer '59, and turn the dial until the pointer points to a copy-paper indicator strip 56, 57 or 58 corresponding to the copy-paper being used. This dial positioning automatically sets the speed of the machine in the range where optimum copies are produced with the particular type of copy-paper being used in the machine. For finer adjustment of machine speed by the operator within the optimum speed range represented by the circumferential length of the strip 56, 57 or 58, the operator may turn the dial to any selected position wherein a portion of the strip remains in alignment with the needle pointer.

Of course, other temperature responsive speed control correlating means enabling presetting of machine speed in accordance with the temperature of the exposure zone than those particularly illustrated and described hereinbefore are possible.

Thus, it is possible to provide -a completely automatic temperature responsive speed control system utilizing a temperature sensing-roller arrangement such as that described hereinbefore by directly connecting a temperature sensing device with a speed control mechanism whereby upon operation of the machine the rate of passage of the composite past the radiation source is automatically controlled. For example, a thermistor sensing unit can be coupled with an electrical signal (indicating means), e.g. a thyratron circuit, a magnetic amplified circuit, etc., to operate a suitable motor speed control, which control automatically varies the roller speed by suitable mechani cal or electrical means.

We claim:

1. In a thermocopying machine having a source of intense radiation, and means for advancing a composite of a graphic original and a heat sensitive copy-paper past said radiation source including speed control means for controlling the rate of passage of said composite past said radiation source, means for correlating the speed of pas sage of said composite past said radiation source with the internal temperature of said machine, said correlating means including a heat insulating body having a radiation reflective surface adjacent said radiation source and over which said composite is drawn past said radiation source, said body and said radiation source providing a copy exposure zone therebetween wherein the graphic information on the graphic original is reproduced on the copypaper as the composite is drawn past said radiation source, temperature sensing means mounted within said machine for registering temperature variations in said copy exposure zone, and indicating means correlating said temperature sensing means and said speed control means whereby the rate of passage of said composite through said exposure zone is controllable in response to temperature variations sensed by said sensing means.

2. In a thermocopy machine, means for advancing a composite of a graphic original and a heat sensitive copypaper past a source of intense radiation to reproduce graphic information of the original on the copy-paper, said means including a heat insulating roller having a highly reflective surface disposed adjacent to and spaced from said radiation source, means for advancing the composite through the machine past said radiation source over said reflective surfaced insulating roller while maintaining the graphic original and copy-paper in pressure contact with one another, speed control means operably connected to said composite advancing means for controlling the rate of passage of the composite past said radiation source, and temperature sensing means adjacent said radiation source, temperature indicating means operatively connected to said sensing means and correlated with said speed control means to facilitate presetting of said speed control means in accordance with the positioning of said temperature indicating means before advancing the composite past said radiation source to obtain optimum reproduction of graphic information on the copy-paper from the graphic original.

3. In a thermocopy machine, means for advancing a composite of a graphic original and a heat sensitive copy-paper past a source of intense radiation to reproduce graphic information of the original on the copypaper, said means including a heat insulating roller having a highly reflective surface disposed adjacent to and spaced from said radiation source, means for advancing the composite through the machine past said radiation source over said reflective surfaced insulating roller while maintaining the graphic original and copy-paper in pressure contact with one another, speed control means operably connected to said composite advancing means for controlling the rate of passage of the composite past said radiation source, and temperature sensing means adjacent said radiation source, said sensing means being mounted Within said machine so as to remain insulated from direct conductive contact with machine parts while being disposed within the space adjacent the copy exposure zone formed between said radiation source and said reflective surfaced insulating roller to sense convection and reflective radiation effects within such air space, temperature indicating means operatively connected to said sensing means and correlated with said speed control means to facilitate presetting of said speed control means in accordance with the positioning of said temperature indicating means before advancing the composite past said radiation source to obtain optimum reproduction of graphic information on the copy-paper from the graphic original.

4. In a thermocopying machine, means for advancing a composite of a graphic original and a heat sensitive copy-paper past a source of intense radiation, reflector means directing radiation from said radiation source toward a heat insulating roller having a highly reflective surface, means for advancing a composite of a graphic information containing original sheet and a sheet of copy-paper over said roller through the copy exposure zone formed by the path of radiation between said roller and said heat source While maintaining the sheets in pressure contact With one another, temperature sensing means mounted within said machine in the air space adjacent said exposure zone and insulated against significant conduction from machine parts, temperature indicating means operatively connected to said sensing means for movement in response to changes in temperature sensed by said sensing means, speed control means operatively connected to said advancing means and correlated with said indicating means for presetting the rate of advance for optimum copy reproduction from the composite in accordance with the indication of said indicating means.

5. In a thermocopying machine having a source of intense radiation, and means for advancing a composite of a graphic original and a heat sensitive copy-paper past said radiation source including speed control means for controlling the rate of passage of said composite past said radiation source, means for correlating the speed of passage of said composite past said radiation source with the internal temperature of said machine, said correlating means including a heat insulating body having a radiation reflective surface adjacent said radiation source and over which said composite is drawn past said radiation source, said body and said radiation source providing a copy exposure zone therebetween wherein the graphic information on the graphic original is reproduced on the copy-paper as the composite is drawn past said radiation source, temperature sensing means mounted Within said machine for registering temperature variations in said copy exposure zone, and temperature indicating means operatively connected to said temperature sensing means and means correlating said indicating means With said speed control means whereby the rate of passage of said composite through said exposure zone can be preset before advancing such composite through said exposure zone.

6. In a thermocopying machine useful in consistently making good copies of graphic originals under variable copying conditions and including a line source of intense radiation, roller and transparent belt means for advancing a composite of graphic original and heat sensitive copy sheet in mutually heat-conductive pressure-contact through a radiation zone horizontally closely adjacent said source to cause thermographic copying of said original on said copy sheet, and means for controlling the rate of advance of said composite through said zone, the combination comprising: a highly radiation-reflective roller having a heat-insulating surface layer for supporting said composite beneath said transparent belt during irradiation; temperature sensing means mounted vertically just above said radiation zone in position for sensing convection and reflective radiation efiFects while being insulated from direct heat-conductive contact with heatconductive machine parts; and temperature indicating means operatively connected to said sensing means and correlated with said rate of advance controlling means.

References Cited in the file of this patent UNITED STATES PATENTS

Claims

1. IN A THERMOCOPYING MACHINE HAVING A SOURCE OF INTENSE RADIATION, AND MEANS FOR ADVANCING A COMPOSITE OF A GRAPHIC ORIGINAL AND A HEAT SENSITIVE COPY-PAPER PAST SAID RADIATION SOURCE INCLUDING SPEED CONTROL MEANS FOR CONTROLLING THE RATE OF PASSAGE OF SAID COMPOSITE PAST SAID RADIATION SOURCE, MEANS FOR CORRELATING THE SPEED OF PASSAGE OF SAID COMPOSITE PAST SAID RADIATION SOURCE WITH THE INTERNAL TEMPERATURE OF SAID MACHINE, SAID CORRELATING MEANS INCLUDING A HEAT INSULATING BODY HAVING A RADIATION REFLECTIVE SURFACE ADJACENT SAID RADIATION SOURCE AND OVER WHICH SAID COMPOSITE IS DRAWN PAST SAID RADIATION SOURCE, SAID BODY AND SAID RADIATION SOURCE PROVIDING A COPY EXPOSURE ZONE THEREBETWEEN WHEREIN THE GRAPHIC INFORMATION ON THE GRAPHIC ORIGINAL IS REPRODUCED ON THE COPYPAPER AS THE COMPOSITE IS DRAWN PAST SAID RADIATION SOURCE, TEMPERATURE SENSING MEANS MOUNTED WITHIN SAID MACHINE FOR REGISTERING TEMPERATURE VARIATIONS IN SAID COPY EXPOSURE ZONE, AND INDICATING MEANS CORRELATING SAID TEMPERATURE SENSING MEANS AND SAID SPEED CONTROL MEANS WHEREBY THE RATE OF PASSAGE OF SAID COMPOSITE THROUGH SAID EXPOSURE ZONE IS CONTROLLABLE IN RESPONSE TO TEMPERATURE VARIATIONS SENSED BY SAID SENSING MEANS.