US3851403A

US3851403A - Apparatus for conditioning sheets of photosensitive materials

Info

Publication number: US3851403A
Application number: US00350829A
Authority: US
Inventors: G Maurischat; J Mueller
Original assignee: Agfa Gevaert AG
Current assignee: Agfa Gevaert AG
Priority date: 1972-04-19
Filing date: 1973-04-13
Publication date: 1974-12-03
Anticipated expiration: 1991-12-03
Also published as: DE2219109B2; DE2219109C3; DE2219109A1

Abstract

Apparatus for conditioning sheets of photosensitive material with streams of heated gaseous fluid which comprises an elongated conditioning chamber through which the material to be treated travels along a horizontal path. The chamber is connected with two nozzles which receive gaseous fluid from one or more blowers and have orifices discharging streams of fluid against the respective sides of sheet material in the conditioning chamber. The fluid is heated by coils which are installed in the nozzles and whose circuits are controlled by temperature measuring devices having thin tungsten wires installed in the respective orifices and serving to produce signals which are indicative of the temperature of fluid streams. Such signals are utilized to complete or open the circuits of the respective heating coils by way of differential amplifiers and power switches.

Description

aurischat et a1.

[ 1- APPARATUS FOR CONDITIONING SHEETS 0F PHOTOSENSITTVE MATERIALS [75] Inventors: Guenther Maurischat; Juergen Mueller, both of Munich, Germany .[73] Assignee: AGFA-Gevaert Aktiengesellschaft,

Leverkusen, Germany [22] Filed: Apr. 13, 1973 [21] Appl. No.: 350,829

[30] Foreign Application Priority Data [58] Field of Search 34/48, 156, 155, 154, 152, 34/151, 162, 160, 153, 46; 73/342 [56 References Cited UNITED STATES PATENTS 1,261,086 4/1918 Wilson et a1 73/342 2,166,935 7/1939 Adams 73/342 Dec. 3, 1974 Primary ExaminerChar1es J. Myhre Assistant ExaminerPaul Devinsky Attorney, Agent, or FirmMichae1 S. Striker 57 ABSTRACT Apparatus for conditioning sheets of photosensitive material with streams of heated gaseous fluid which comprises an elongated conditioning chamber through which the material to be treated travels along a horizontal path. The chamber is connected with two nozzles which receive gaseous fluid from one or more blowers and have orifices discharging streams of fluid against the respective sides of sheet material in the conditioning chamber. The fluid is heated by coils which are installed in the nozzles and whose circuits are controlled by temperature measuring devices having thin tungsten wires installed in the respective orifices and serving to produce signals which are indicative of the temperature of fluid streams. Such signals are utilized to complete or open the circuits of the respective heating coils by way of differential amplifiers and power switches.

8 Claims, 4 Drawing Figures 2,645,031 7/1953 Edwards 34/156 2,874,482 2/1959 Haltmeier 34/48 3,082,540 3/1963 Hiltenbrand... 34/48 3,293,775 12/1966 Kitrosser 34/156 3,346,932 10/1967 Cheape 34/155 3,426,441 2/1969 Broski 34/48 3,483,750 12/1969 Pratt 73/342 3,545,364 12/1970 Reedy 34/155 3,548,512 12/1970 Shoot 34/151 PATENTELBEB 31914 I 3,8513103 I SHEEIIOFZ APPARATUS FOR CONDITIONING SHEETS F PHOTOSENSITIVE MATERIALS CROSS-REFERENCE TO RELATED APPLICATION The conditioning apparatus of the present invention constitutes a further development of and an improvement over the apparatus disclosed in commonly owned copending application Ser. No. 300,992 filed Oct. 26, 1972 by Stievenar t, et al.

BACKGROUND OF THE INVENTION The present invention relates to apparatus for conditioning sheets or webs of photosensitive material while such material travels lengthwise through a conditioning chamber. A suitable conditioning chamber but with different heating means for conditioning fluid is disclosed in the aforementioned copending application Ser. No. 300,992 of Stievenart, et al.

. The apparatus which is disclosed in the application Ser. No. 300,992 comprises a horizontal conditioning chamber and two assemblies of transporting rolls which advance sheets of photosensitive material along an elongated horizontal path extending through the conditioning chamber. The material which travels through the chamber is treated by two streams of heated air 'which is admitted by way of orifices provided in two nozzles which constitute separable or integral parts of the conditioning chamber. The temperature of air is measured in the interior of the conditioning chamber and the results of such measurement are utilized to regulate the temperature of air streams.

It has been found that the measurement of fluid temperature in the interior of the conditioning chamber cannot invariably insure that the temperature of conditioning fluid will remain within a narrow range. Such regulation of the temperature of conditioning fluid is often important in order to prevent overheating of photosensitive material. Furthermore, the energy requirements of suchconditioning apparatus are rather high so that it is desirable to operate the heating means for conditioning fluid with maximum efficiency and economy. To this end, the blower or blowers which supply heated air into the conditioning chamber are normally turned on only when the transporting rollersactually advance sheet-like material through the conditioning chamber.

. Such mode of operation necessitates an even more accurate regulation of fluid temperature in order to avoid underheating of sheet material when the operation of the blower or blowers is started or overheating of sheet material when the blower or blowers are operated for longer periods of time.

SUMMARY OF THE INVENTION An object of the invention is to provide a conditioning apparatus for sheets or webs of photosensitive material with novel and improved means for regulating the temperature of conditioning fluid.

Another object of the invention is to provide the conditioning apparatus with combined heating and heat regulating means which occupy little room and can be installed in certain presently known types of conditioning apparatus.

A further object of the invention is to provide a conditioning apparatus for sheets or webs of photosensitive material wherein the temperature of conditioning fluid can be maintained within an extremely narrow range, even if the conditioning fluid is supplied intermittently.

Still another object of the invention is to provide a conditioning apparatus wherein the temperature of conditioning fluid can be regulated at the will of the operator so as to insure that the conditioning action of fluid is .best suited for a particular type of photosensitive material. V

Another object of the invention is to provide a conditioning apparatus whose operation is more economical than the operation of presently known conditioning ap-' paratus.

The invention is embodied in an apparatus for conditioning sheet-like commodities, particularly for drying sheets or webs of photosensitive material. The apparatus comprises a conditioning chamber having an inlet end and adischarge end, conveyor means which serves to transport sheet-like commodities along an elongated path extending through the chamber so that successive commodities respectively enter and leave the conditioning chamber by way of the inlet end and the discharge end, at least one source of conditioning fluid (preferably air), at least one nozzle which is connected with the source of conditioning fluid and withthe conditioning chamber and has an elongated orifice extending transversely of the path for sheet-like commodities and is arranged to discharge conditioning fluid against one side of a commodity in the path within the conditioning chamber, and novel and improved control means for regulating the temperature of conditioning fluid. x

The control means comprises a temperature measuring device which serves to produce signals indicating the temperature of conditioning fluid in the orifice of the nozzle and includes elongated temperature monitoring means which is installed in the orifice and preferably consists of extremely thin tungsten wire, adjustable heating means for the fluid, and means for adjusting the heating means in response to signals from the temperature monitoring means. The meansfor adjust ing the heating means may comprise a differential amplifier and a power switch. The output of the amplifier can cause the power switch to complete the circuit of the heating means (preferably one or more coils which are installed in the interior of the nozzle). The amplifier has a first input which is connected with the temperature monitoring means and a second input which is preferably connected with a second signal generating device, such as a voltage divider including a variable resistor. The power switch completes or initiates completion of the circuit of the heating means only when the intensity of signals furnished by the temperature monitoring means is less than the intensity of the signal which is furnished by the second signal generating means.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved conditioning appara- BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a fragmentary vertical sectional view of a conditioning apparatus which embodies the invention;

FIG. 2 is an enlarged fragmentary transverse vertical sectional view of the lower fluid-admitting nozzle of the conditioning apparatus shown in FIG. 1, the section of FIG. 2 being taken in the direction of arrows as seen from the line II-II in FIG. 3;

FIG. 3 is a sectional view as seen in the direction of arrows from the line III-III in FIG. 2; and

FIG. 4 is a circuit diagram of the control means for regulating the temperature of conditioning fluid in the nozzle of FIGS. 2 and 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates a conditioning apparatus which is similar to the apparatus disclosed in the aforementioned copending application Ser. No. 300,992 of Stievenart, et al. The conditioning apparatus comprises a housing or frame including a lower portion 101 and an upper portion 103. The lower portion 101 is provided with a horizontal pivot member 102 for the upper portion 103 which is pivotable with respect to the lower portion 101 between the illustrated operative position and an open position in which the interior of the drying or conditioning chamber 100 of the apparatus is readily accessible.

The lower portion 101 of the housing is provided with vertical slots 101a (only one shown) for the shafts 104 and 106 of two horizontal transporting rolls 106 and 107. At least one of the rolls 106 and 107 is driven so as to advance a sheet of photosensitive material 114 (re-presented by a phantom line) in the direction indicated by arrow B when the leader of such material is introduced into the nip of the rolls 106 and 107. The rolls I06 and 107 form part of a conveyor system for sheet material, and this conveyor system further comprises two additional sets of rolls which are mounted in the housing close to the pivot member 102 and cooperate with the rolls 106 and 107 to advance sheet material along a substantially horizontal path. The additional sets of rolls include a lower set 109a-109d mounted on a lower horizontal shaft 108, and an upper set of rolls Illa-1110 mounted on an upper horizontal shaft 110. The exact manner in which the rolls 109a-I09d and Illa-1110 are distributed, as considered in the direction at right angles to the travel of sheet material 114, is illustrated in FIG. 2 of the copending application Ser. No. 300,992 to which reference may be had if necessary. The shaft 108 is mounted in the lower portion 101 and the shaft 110 is mounted in the upper portion 103 of the housing. At least one of the

shafts

108, 110 is driven in the direction indicated by the arrow, preferably by the drive which transmits torque to the shaft 104 and/or 105.

The conditioning chamber 100 of the apparatus shown in FIG. 1 comprises a lower section 112 which is secured to or forms an integral part of the lower portion 101, and an upper section 113 which is secured to or integral with the upper section 103 of the housing. When the upper portion 103 of the housing assumes the operative position of FIG. 1, the

sections

112 and 113 together form the conditioning chamber 100 which resembles an elongated nozzle tapering in a direction from the transporting rolls 106, 107 toward the

shafts

108, 110. The inlet end of the conditioning chamber is defined by the front or foremost portions 112a and 1130 of the

sections

112, 113 in close proximity to the transporting rolls 106 and 107. The discharge end of the chamber 100 is defined by outwardly flaring right-hand end portions 112!) and 113b of the

sections

112, 113. The end portions 1l2b and 113b form a shield which surrounds portions of the transporting rolls 109a-109d and Illa-111C.

The conditioning apparatus further comprises two fluid-admitting nozzles and 116 which are respectively integral with or secured to the sections 113 and 1 12. The source of gaseous conditioning fluid is a radial blower 117 which is shown as being adjacent to the inlet end of the lower nozzle 116. The blower 1 17 is assumed to admit compressed conditioning fluid to both nozzles but it is equally within the purview of the invention to provide a separate blower for each of the

nozzles

115, 116. The directions in which the conditioning fluid flows in the

nozzles

115 and 116 are respectively indicated by arrows C and D. The upper nozzle 115 has a relatively narrow orifice 115e which extends transversely of the path for sheet material 114 and has a length which equals or approximates the width of sheet material. The orifice 1l6e of the lower nozzle 116 ispreferably mirror-symmetrical to the orifice 115e with reference to the plane of the sheet material 114. Those portions of the

nozzles

115 and 116 which are adjacent to the conditioning chamber 100 resemble funnels and taper toward the path for sheet material 114. The orifices 115e and l16e respectively constitute the narrowest portions of the passages wherein the conditioning fluid flows through the

nozzles

115 and 116 to impinge against the respective sides of sheet material 114 between the transporting

rolls

106, 107 and 109a-109d, 111a-111c. The streams of conditioning fluid which pass through the orifices 1l5e and 116e impinge upon the sheet material 114 substantially at right angles to the plane of the aforementioned path. The portions 115a and 116a of the

nozzles

115 and 116 respectively flank the upstream sides of the orifices 115e and ll6e immediately downstream of the inlet end 112a, 113a. The nozzle portions 115a and 116a extend rather close to the path for sheet material 114 so as to reduce the likelihood of flow of conditioning fluid counter to the direction indicated by the arrow B.

The portions 115b and ll6b of the

nozzles

115, 116 are respectively located immediately downstream of the orifices 1l5e and 116e and extend inwardly beyond the adjacent internal surfaces of the

chamber sections

113 and 112 so as to create in the conditioning fluid turbulence which is indicated schematically by the arrows E and F. The streams of conditioning fluid which respectively enter by way of the orifices 115s and 1162 are deflected in a direction to the right, as viewed in FIG. 1, after they impinge upon the respective sides of sheet material 114 and are thereby caused to travel along the projections 11512, 116b which create turbulence (arrows E and F) during flow of conditioning fluid toward the discharge end 112b, 113b. It has been found that the provision of

projections

115b, 116b greatly enhances the conditioning action of fluid in the chamber 100. Results of experiments with the conditioning apparatus of FIG. 1 indicate that the conditioning action is most satisfactory when the fluid is conveyed at a speed of 8-15 m/sec.

In accordance with a feature of the invention, the conditioning apparatus further comprises novel and improved control means for regulating the temperature of conditioning fluid which is being admitted into the chamber 11111 by the

nozzles

115 and 116. The control means preferably comprises two discrete control units, one for each of the

nozzles

115 and 116. The control unit which is illustrated in FIGS. 2, 3 and 4 is installed in the lower nozzle 116 of FIG. 1. The other control unit is not shown because it is preferably identical with the control unit in the nozzle 116.

The control unit for conditioning fluid which enters the conditioning chamber 100 by way of the nozzle 116 comprises a carrier or insert 119 resembling a hollow funnel which is fitted into a similarly configurated inner portion of the nozzle 116. The corresponding carrier or insert in the upper nozzle 115 is indicated in FIG. 1 by the reference character 118. The internal surface of the nozzle 116 is provided with a recess 1116c which receives the side walls 119a and 11% of the carrier 119. The side wall 119a and 11% consist of sheet metal and are connected to each other by two transversely extending end walls or ribs 11% and 119d. At least the ribs 1119c and 119d preferably consist of insulating material. For example, the

ribs

119 c and 119d may be made of asbestos or a ceramic material.

The control unit of FIGS. 2 to 41 further comprises prises a pulse generator which is connected with the heating means here shown as including three elongated electric heating coils 1211 which extend between the ribs 11% and 119d. Each of the coils 1211 extends through an opening 1119f provided therefor in the rib 1190. The ribs 119:: and 1194 are further provided with registering bores 11% for a thin tungsten wire 121 which constitutes an elongated temperature monitoring element of the control unit. The wire 121 is assumed to have a diameter which is less than one-tenth of one millimeter (for example 0.06 mm) and this wire is under sufficient tension so that it remains straight and is capable of monitoring the temperature of conditioning fluid in or close to the narrowest portion of the orifice 116e. It is clear that the material of the wire 121 can be any other substance whose temperature coefficient and specific resistance are similar to that of tungsten.

FIG. 4 illustrates the circuit diagram of the heretofore described and other elements of the control unit in the nozzle 116. The wire 121 is connected in series with another resistor 126 of the temperature measuring device. The resistor 126 is connected to a source of DC current (not shown) and the resistor 126 is connected with parallel with two

additional resistors

122, 123. The

resistors

122, 123 constitute a voltage divider having a tap 122a which is connected to one input of a differential amplifier 12 1. The tap 121a between the resistor 126 and wire 121 is connected with another input of the amplifier 124. The output of the amplifier 121 is connected with the heating coils 120 (only one shown in FIG. 1) by way of a power switch here shown as a diode 125. The resistor 122 is a variable resistor and serves to transmit to the corresponding input of the amplifier 126 a signal which is indicative of the desired temperature of conditioning fluid which flows through the orifice 116e and into the conditioning chamber 100. The resistor 122 may be adjusted when the operator wishes to change the temperature of conditioning fluid in the nozzle 116.

The exact details of the amplifier 12d form no part of this invention. As shown, the amplifier 124 comoutput. The arrangement is such that, when the blower 117 is on so that the nozzle 116 discharges into the chamber 1110 a narrow stream of conditioning fluid, the temperature of such fluid is measured by the wire 121. The signal which is transmitted from the tap 121a to the corresponding input of the amplifier 124 is compared with the signal from the variable resistor 122.

sensitive material has been introduced into the nip of the transporting rolls 106, 107 so that the sheet begins to advance in the direction indicated by the arrow B. Depending on the desired mode of operation, the blower 117 is driven continuously or is started in automatic response to introduction of sheet material into the chamber 100. Such entry can be detected by a suitable photoelectric scanner, not shown. Whenever the blower 117 is started, the temperature of the initially conveyed streams of conditioning fluid which flow through the orifices e, 116e of the

nozzles

115, 116 is lower than the desired temperature as selected by the respective variable resistors 122. The temperature of inflowing conditioning fluid is detected by the respective wires 121 whereby the signals from the taps 121a to the respective inputs of the associated differential amplifiers 124 indicate that the fluid is too cold, ie, that its temperature is less than that represented by the signals from the taps 122a. Therefore, the amplifiers 124 cause the respective diodes 125 to complete or to initiate completion of the circuits of the heating coils 1211 with the result that the fluid is heated and rapidly reaches the selected temperature. The wires 121 are mounted in the

orifices

115e, 116e so that they are capable of immediately reacting to changes in the temperature of respective fluid streams. The resistance of the wires 121 changes accordingly and, as soon as the wires are heated to a temperature which exceeds the desired or preselected temperature, the intensity of signals from the taps 121a exceeds the intensity of signals from the corresponding taps 1220. This causes the amplifiers 121 to disconnect the heating coils from the energy source by way of the respective diodes 125. The diodes 1125 again complete the circuit of the coils 120 as soon as the temperature of inflowing conditioning fluid decreases below the preselected temperature, and the wires 121 monitor the rising temperature of fluid streams in the orifices 115e, 1162 and cause the amplifiers 124 to disconnect the coils 120 from the energy source as soon as the temperature of fluid streams rises to the desired value. The same procedure is repeated again and again with the result that the temperature of fluid which flows through the

nozzle

115 or 116 cannot decrease well below and cannot rise well above the preselected temperature. The diameters of the wires 121 are so small that they cannot unduly affect the flow of conditioning fluid in the respective orifices. Also, the heat storing capacities of the wires 121 are negligible.

As mentioned before, tungsten is but one of various substances which can be used as the material for the temperature monitoring elements in the orifices 11542 and 1 16s. Such other substances may include metals or nonmetallic materials whose specific resistance to the flow of current varies substantially in response to temperature changes and which are capable of standing the maximum temperature of conditioning fluid and of the heating coils if the monitoring elements are installed close to the heating means. The temperature monitoring elements 121 are readily accessible for inspection in response to pivoting of the upper housing section 103 to its open position.

An important advantage of temperature monitoring elements in the form of wires which are mounted in or close to the narrowest portions of the orifices 115e, ll6e is that they are influenced by the entire streams of conditioning fluid which flow into the chamber 100, i.e., that they can produce or cause the generation of signals which are indicative of the average temperature of inflowing conditioning fluid. Moreover, the placing of temperature monitoring elements into the

orifices

115e, 116e insures that their heating or cooling by fluid streams flowing at a high speed into the conditioning chamber 100 is very intensive so that they can immediately detect even minor changes in the temperature of fluid.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of our contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

1. In an apparatus for conditioning sheet-like commodities, particularly for drying sheets or webs of photosensitive material, a combination comprising a conditioning chamber having an inlet end and a discharge end; conveyor means for transporting sheet-like commodities along an elongated path extending through said chamber so that successive commodities respectively enter and leave said chamber by way of said inlet end and said discharge end; at least one source of conditioning fluid; at least one nozzle connected with said source and having an elongated orifice extending substantially transversely of said path and arranged to discharge conditioning fluid against one side of a commodity in said path, said nozzle having an elongated passage for the flow of fluid from said source toward said path, said passage having portions of different width and said orifice constituting the narrowest portion of said passage; and control means for regulating the temperature of conditioning fluid, comprising a temperature measuring device arranged to produce signals indicating the temperature of conditioning fluid in said orifice and including elongated temperature monitoring means installed in and extending lengthwise of said orifice, across the full width of a commodity in said path, and across the stream of conditioning fluid passing through said orifice so that said monitoring means is influenced by and indicates the average temperature of the entire stream of conditioning fluid, the transverse dimensions of said elongated monitoring means constituting a small fraction of the width of said orifice, adjustable heating means for conditioning the fluid, and means for adjusting said heating means in response to said signals so that the conditioning action of said heating means upon the fluid is a function of the average temperature of fluid in said orifice as detected by said monitoring means.

2. A combination as defined in claim 1, wherein said temperature monitoring means is a wire consisting of a material whose resistance to the flow of electric current changes substantially in response to changes in temperature.

3. A combination as defined in claim 2, wherein said wire consists of tungsten.

4. A combination as defined in claim 2, wherein the diameter of said wire is less than one-tenth of one millimeter.

5. A combination as defined in claim 1, wherein said control means further comprises a carrier for said monitoring means and said adjustable heating means. said carrier being located in the interior of said nozzle.

6. A combination as defined in claim 5, whereinsaid nozzle includes a funnel-shaped portion and said carrier is a hollow funnel which is received in said funnelshaped portion of said nozzle.

7. A combination as defined in claim 1, wherein said means for adjusting said heating means comprises an amplifier having a first input connected with said temperature measuring device and a second input, and second signal generating means connected with said second input to transmit to said amplifier a second signal whose intensity is indicative of the desired temperature of conditioning fluid, said amplifier further having an output connected with said heating means and comprising means for actuating said heating means when the intensity of signals furnished by said temperature measuring device is less than the intensity of said second signal.

8. A combination as defined in claim 7, wherein said second signal generating means includes a variable resistor.

Claims

3. A combination as defined in claim 2, wherein said wire consists of tungsten.

5. A combination as defined in claim 1, wherein said control means further comprises a carrier for said monitoring means and said adjustable heating means, said carrier being located in the interior of said nozzle.

6. A combination as defined in claim 5, wherein said nozzle includes a funnel-shaped portion and said carrier is a hollow funnel which is received in said funnel-shaped portion of said nozzle.