EP0915395A1 - Photothermographic development system - Google Patents

Photothermographic development system Download PDF

Info

Publication number
EP0915395A1
EP0915395A1 EP98203612A EP98203612A EP0915395A1 EP 0915395 A1 EP0915395 A1 EP 0915395A1 EP 98203612 A EP98203612 A EP 98203612A EP 98203612 A EP98203612 A EP 98203612A EP 0915395 A1 EP0915395 A1 EP 0915395A1
Authority
EP
European Patent Office
Prior art keywords
drum
heating
temperature
revolution
unit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP98203612A
Other languages
German (de)
English (en)
French (fr)
Inventor
Martin Agfa-Gevaert N.V De Kegelaer
Leo Agfa-Gevaert N.V Oelbrandt
Marc Agfa-Gevaert N.V De Niel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Agfa Gevaert NV
Original Assignee
Agfa Gevaert NV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Agfa Gevaert NV filed Critical Agfa Gevaert NV
Publication of EP0915395A1 publication Critical patent/EP0915395A1/en
Withdrawn legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/20—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat
    • G03G15/2003—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat
    • G03G15/2014—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat using contact heat
    • G03G15/2039—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat using contact heat with means for controlling the fixing temperature
    • G03G15/2042—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat using contact heat with means for controlling the fixing temperature specially for the axial heat partition
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03D—APPARATUS FOR PROCESSING EXPOSED PHOTOGRAPHIC MATERIALS; ACCESSORIES THEREFOR
    • G03D13/00—Processing apparatus or accessories therefor, not covered by groups G11B3/00 - G11B11/00
    • G03D13/002—Heat development apparatus, e.g. Kalvar

Definitions

  • This invention relates to an apparatus and a method of developing a photothermographic material. More particularly, the present invention comprises the dry processing of a photothermographic material, also referred to as "image-forming element". A very specific application is in the market for dry-processable medical film.
  • thermothermographic materials Thermally developable silver-containing materials for making images by means of exposure and then heating are referred to as photothermographic materials and are generally known.
  • “Dry Silver®” materials from Minnesota Mining and Manufacturing Company.
  • a typical composition of such thermographically image-forming elements contains photosensitive silver halides combined with an oxidation-reduction combination of, for example, an organic silver salt and a reducing agent for it. These combinations are described, for example, in US Patent No. 3,457,075 (Morgan) and in "Handbook of Imaging Science” by D. A. Morgan, ed. A. R. Diamond, published by Marcel Dekker, 1991, page 43.
  • thermographic systems A review of thermographic systems is given in the book entitled “Imaging systems” by Kurt I. Jacobson and Ralph E. Jacobson, The Focal Press, London and New York, 1976, in Chapter V under the title “Systems based on unconventional processing” and in Chapter VII under the title "7.2 Photothermography”.
  • Photothermographic image-forming elements are typically processed by an imagewise exposure, for example, in contact with an original or after electronic image processing with the aid of a laser, as a result of which a latent image is formed on the silver halide. Further information about such imagewise exposures can be found in Agfa-Gevaert Patent Application EPA-96.201.530.1
  • the latent image formed exerts a catalytic influence on the oxidation-reduction reaction between the reducing agent and the nonphotosensitive organic silver salt, usually silver behenate, as a result of which a visible density is formed at the exposed points.
  • the development conditions are determined by the choice of the nonphotosensitive organic silver salt and its reducing agent. For example, the development temperature is in the vicinity of 120°C and this is for about 5 seconds.
  • thermographic materials can be found, for example, in said Patent Application EP-A-96.201.530.1.
  • FIG. 1 shows the whole of a photothermographic system according to Patent Application DE 196 36 235 in the name of Agfa-Gevaert A.G., in which exposure and development take place on one and the same medium.
  • thermal processors of this type have, however, one or more disadvantages, such as thermal inertia (as a result of which the processing time becomes prohibitive), excessively high pressures (resulting in possible disadvantages, such as scratches or creases), uneven pressures and/or uneven temperature distribution (resulting in undesirable density differences).
  • the present application presents an alternative thermal processing with relatively short development times and without undesirable density differences.
  • the object of this invention is to provide an apparatus or system and a method or process for uniformly developing a photothermographic material implying that substantially equal temperatures occur during the development at all points on said photothermographic material.
  • Another object of this invention is to provide a method and an apparatus for developing a photothermographic material at a temperature which remains constant with time.
  • body of revolution is understood as meaning a “(geometrical) body which is considered to have arisen by rotating a surface around an axis, the axis of revolution" (cf. "Groot woordenboek der Nederlandse taal" ("Large-dictionary of the Dutch language”), published by Van Dale Lexic rising, Utrecht-Antwerp, 1984 edition, part two J-R, page 1883). Any cross-section at right angles to said axis of revolution therefore forms a circle.
  • a cylindrical drum or "drum” for short, is a special case of a body of revolution.
  • heating unit comprises various heating possibilities (for example, resistive via an ohmic resistor or via a lamp; or inductively) and various practical application facilities (without relation to any photographic material and therefore not limited to photography)
  • development apparatus is more specific is explicitly intended to develop a photographic material and is primarily directed at photothermophotography and direct thermography.
  • laser printer printer
  • printer laser recorder
  • recorder recorder
  • registration system it being possible for desired information to be written in with a laser, but possibly also with other means (such as cathode ray tubes (CRTs), light-emitting diodes (LEDs), luminescence panels, phosphor screens, etc).
  • CTRs cathode ray tubes
  • LEDs light-emitting diodes
  • luminescence panels phosphor screens, etc.
  • FIG. 1 shows the whole of a photothermographic system 1 according to Patent Application DE 196 36 235.0-51 in the name of Agfa-Gevaert, in which exposure and development take place on one and the same medium, in this case preferably on a so-called body of revolution.
  • SDP single drum printer
  • Figure 1 can nevertheless serve as a basis for the outline description of a photothermographic system.
  • laser printer 1 will first expose the image material 10 in an exposure unit 3 and then develop it in a thermal development unit 4.
  • laser printer 1 will first expose the image material 10 and then develop it in a common exposure and development unit 5. After processing, information is observable on the image material because nonexposed, developed zones are transparent and exposed and developed zones have an observable optical density (preferably with a maximum density above 3.5 D).
  • one film sheet 10 is picked up from feed unit 2 (by means of a feed device 15) and transported (in the direction of movement Y along a guide 16) to exposure and development unit 5.
  • the outer casing (of thermally conducting material) of drum 20 (having direction of rotation n) is brought by a heating system 60 to a desired process temperature (for example, 123°C or 396 K) and kept at said temperature by at least one temperature sensor (for example, a thermocouple or a thermistor) and a control circuit (shown in Figure 9 and to be discussed later.
  • a desired process temperature for example, 123°C or 396 K
  • at least one temperature sensor for example, a thermocouple or a thermistor
  • a control circuit shown in Figure 9 and to be discussed later.
  • Film 10 is pressed against rotating drum 20 by means of rollers 31-33 and transport means 40, preferably a conveyor belt 41 (generally made of thermally insulating material) so that film 10 achieves virtually the same temperature as the outside surface of drum 20.
  • a conveyor belt 41 generally made of thermally insulating material
  • modulated laser beam 57 inscribes the image material 10 at a sensitometrically suitable wavelength and with an imagewise-modulated intensity.
  • film 10 is developed thermally so that a permanent blackening is produced at the exposed points.
  • film 10 is pressed by conveyor belt or pressure belt 41 against the heated drum 20 and moved synchronously in the direction of rotation n.
  • the contact tension can be influenced by adjusting tension roller 36.
  • the development time can also be influenced (for example, between 3 and 20 s) by adjusting the contact angle ⁇ (having numerical reference 42) between belt 41 and drum (here shown at approximately 180°C) and by adjusting the speed of rotation.
  • film sheet 10 is brought out via cooling rollers 38-39, which may be cooled by a fan 17, and is made available in a receiving tray 29 of an unloading unit 6.
  • the laser recorder 1 also comprises an electronic control unit 7 and an optical unit 8, which itself comprises yet other components, such as a laser source 51, which makes available an unmodulated laser beam 52, a modulator 53, objectives 54 and 55 and a rotating polygonal mirror 56.
  • Various parameters (such as temperature, speed, contact force, contact angle ⁇ %) can be set by means of an operating panel 9.
  • a cleaning unit 80 provides for the drum to be kept permanently clean by regularly removing any soiling elements which may be present.
  • Figure 5.1 shows a diagrammatic view of a photothermographic material (m) which can be used in the present invention
  • Figure 5.2 in which a cylindrical drum is heated internally by, for example, an electrically resistant medium (for example, a so-called ohmic resistor which generates a Joule effect).
  • an electrically resistant medium for example, a so-called ohmic resistor which generates a Joule effect
  • Figure 5 shows a temperature variation such as is measured in the axial direction (symbolically indicated by arrow a) on a body of revolution according to the prior art.
  • Figure 5.4 shows the temperature variation as measured in the tangential direction (symbolically indicated by arrow t) on a body of revolution according to the prior art.
  • the surface temperature of the drum may drop locally (see curve ca1) . After the film has left the drum, the surface temperature of the drum rises again to the standby value.
  • second temperature profile Tt The graphical representation of this temperature variation in the tangential direction (t) on the outside surface of the body of revolution is referred to below as "second temperature profile Tt".
  • the present invention discloses an apparatus and a method in which both temperature profiles (Ta, Tt) can be controlled independently of one another even during processing of said image materials.
  • both temperature profiles can be substantially flattened. How this can take place precisely in principle is explained, in particular, in a later section.
  • the physical centrepiece of the present invention comprises a specific drum having a modified heating.
  • the present invention comprises a rotating body of revolution 20 having an outer casing 21 made of thermally conducting a material, axial or lateral end faces 22-23 made of thermally insulating material, and heating means 60, for example an electrically resistant heating element 61, said body of revolution having on the outside surface a temperature variation in the axial direction (a) according to a first temperature profile (Ta) and a temperature variation in the tangential direction (t) according to a second temperature profile (Tt), characterized in that both temperature profiles (Ta, Tt) can be controlled independently of one another and that each of the two temperature profiles has a compensation control.
  • heating means 60 for example an electrically resistant heating element 61
  • Figure 6.1 shows a diagrammatic view of a photothermographic material (m) which can be used in the present invention
  • Figure 6.2 which shows a diagrammatic view of a drum-shaped heating body according to the present invention (a so-called “segmented drum” comprising, for example, three sections 21', 22' and 23', further discussed by reference to Figure 12.1)
  • Figure 6.3 which shows a temperature variation in the axial direction on a heated drum according to the present invention
  • Figures 6.4 and 6.5 which show the temperature variation as measured in the tangential direction on a heated drum according to the present invention.
  • curves ca0, ct0 and ct1 have the same meaning as in Figures 5.2 and 5.3.
  • the other curves show various temperature variations, namely ca2 and ca3 show temperature variations measured in the axial direction on a segmented drum (cf. curve ca2) and on a segmented drum having axial compensation (here still incomplete) (cf. curve ca2) according to the present invention.
  • Curves ct2 and ct3 show temperature variations as measured in the tangential direction on a heated drum having tangential compensation (here complete) according to the present invention curve ct2 showing a situation without image material 10 and curve ct3 a situation with image material.
  • synchronization means are also provided in order to activate the abovementioned means at the correct instants in time.
  • said heating means 60 may comprise an electrically resistant heating element 61 and/or an electrical heat radiator 69.
  • the heat transfer between heating means 60 and body of revolution 20 can take place in various ways, namely, in the case of heating element 61, primarily by conduction, and in the case of heat radiator 69 (for example, a ceramic element or a lamp preferably having an infrared spectrum, IR), primarily by radiation.
  • Figures 2 and 3 show an apparatus according to a drum concept.
  • Figures 2.1 and 3 show a cross-section of the apparatus and
  • Figure 2.2 shows a longitudinal section. Said figures are further discussed jointly.
  • the processor comprises a heated drum around which a belt 41 runs, for example, over a contact angle ⁇ of 180°.
  • a number of rollers are provided, two transport rollers 34-35 next to the drum, and at least one tension roller (36 or 37) which provides for tensioning of the belt and controls the belt (so-called tension roller or control roller).
  • said tension roller can be replaced by a plurality of rollers, for example by two rollers (reference 36 and 37) as in Figure 1.
  • the film transport between inlet 46 and outlet 47 of development apparatus 14 takes place by means of a concomitantly rotating conveyor belt 41 which presses the film against the hot drum or cylinder 20.
  • the belt 41 itself is pressed against the heated drum 20 by two rollers 34 and 35.
  • the contact angle, ⁇ of the belt can be adjusted from a few degrees to 180°, even to approximately 280° by positioning said rollers 34 and 35, and their diameter.
  • the roller 36 provides for the tensioning of the belt 41 against the drum 20. This can take place either as a result of the weight of the roller 36 itself (cf. gravity) or, for example, as a result of a force applied via the bearing of said roller 36. This latter has the advantage that the apparatus can be arranged at an angle or even vertically without the tensioning force of the belt 41 being influenced.
  • the present invention thus describes a heating unit (4) comprising a body of revolution (20) having an outer casing (21) made of thermally conducting material and axial end faces (22-23) made of thermally insulating material, rotation means for rotating said body of revolution, heating means (60) for heating said body of revolution, measuring means (68) for measuring on said body of revolution at least one temperature to determine a temperature variation in the axial direction (a) according to a first temperature profile (Ta) and at least one temperature to determine a temperature variation in the tangential direction (t) according to a second temperature profile (Tt), conversion means (76) for converting said temperatures into corresponding (measured and digitized temperature measurements) temperature signals (77), control means (72-74) for converting said temperature signals into control signals (78) for said heating means.
  • a body of revolution 20 preferably in the form of a cylinder or drum.
  • the drum is mounted in a heat-insulating material, for example, so-called hard fabric having adequate resistance to high process temperatures (up to 140°C).
  • Hard fabric is a laminate material based on a carrier (usually wool) and a resin (for example, phenol, epoxy or polyimide), it has a thermal conductivity of approximately 0.2 W/m ⁇ K and is subject to international standards such as DIN 7735.
  • Known trade names are Batext, Epratex and Ferrozell; suppliers are, inter alia, Eriks, B2660 Hoboken and Vink, B2220 Heist op den Berg.
  • thermal conductivity of usable construction materials we understand, in the present application, "good conductors” as meaning materials having a thermal conductivity ⁇ greater the 10 W/m ⁇ K and “thermally insulating” as meaning a thermal conductivity ⁇ of less than 3 W/m ⁇ K, preferably less than 0.5 W/m ⁇ K.
  • Said heating means 60 can be bent during manufacture or bent when fitted (preferably according to the radius of curvature of the drum).
  • Said heating element 61 may be an etched foil (for example, supplied by WATLOW, 12001 Lacland Road, St Louis, Missouri 63146, USA), a wire-wound foil (for example, supplied by ELMWOOD, Elm Road, North Shields, Tyne and Wear NE29 8Sa, GB), ...
  • Certain properties (such as thermal conductivity, hardness, roughness %) of the drum surface are very important, this being because of process quality (especially with regard to heat transfer) and because of mechanical resistance to damage.
  • the drum surface must be uniformly heated and must give off the heat uniformly to the film. This requires a surface having equal thermal capacity and thermal conduction coefficient.
  • the drum surface should be hard enough not to be damaged by contact with film and scraper. Damage due to occasional contact with foreign objects for example, during the opening of the processor, during the removal of dust, etc.) must also be avoided.
  • the surface finish is also important. Firstly, the surface should be finely finished enough for no imprints to be left behind in the film during the processing (as a result of the soft emulsion layer, the film is, of course, very susceptible to damage during processing). Secondly, a surface which is insufficiently smooth will be polished by contact with the scraper, as a result of which fine particles may break off the drum surface and remain stuck at the level of the scraping system. Because said particles are very hard, damage to the drum surface and the scraper(s) is real. In an embodiment according to the present invention, the best results are obtained with a re-ground drum surface, preferably with a finish to Ra ⁇ 0.5 ⁇ m and Rz ⁇ 4 ⁇ m (cf. standards DIN 4762 and DIN 4768).
  • an aftertreatment of the drum surface with the aid of a normal anodization of the drum proved insufficiently hard to obtain and to maintain adequate image quality.
  • the drum surface has therefore been hard-anodized (preferably, to a Vickers hardness of approximately 500 HV).
  • Teflon is a trade name for PolyTetraFluoroEthylene (PTFE) and is available, inter alia, from Du Pont, Hoechst, ICI, Montedison).
  • the drum has therefore been subjected to a "hard anodization followed by Teflonization".
  • This technology is known under the name “TUFRAM coating” and comprises a combination of first hard-anodizing and then sealing by smearing the anodization pores with Teflon; in this way “PTFE-impregnated Al 2 O 3 " is obtained.
  • TEZRAM coating comprises a combination of first hard-anodizing and then sealing by smearing the anodization pores with Teflon; in this way “PTFE-impregnated Al 2 O 3 " is obtained.
  • This aftertreatment has an immediate advantage in the fact that a very hard non-stick surface is obtained.
  • Two other important functions which must be fulfilled in the apparatus comprise (1) the reproducible removal of the developed film from the drum and (2) the permanent maintenance of the cleanliness of the drum by means of regularly removing soiling elements.
  • the drum can, in fact, be soiled by various elements, especially dust (from the environment, due to the film manufacture, ...) and emulsion residues.
  • PEN is an abbreviation for PolyEthylene Naphthalate and is produced, inter alia, by the companies Du Pont, ICI and Teijin.
  • Nylon is a polyamide plastic and is produced, inter alia, by the companies BASF, Du Pont and Monsanto.
  • Yet another embodiment uses a thin steel sheet (for example, 0.1 mm thick).
  • a brass scraper (having a thickness of approximately 0.1 mm) provisionally gives the best result. In this connection, it is observed that the brass scraper settles down well to the shape of the drum and that less damage occurs.
  • the drum cleaning function was combined with the film removal function by using one scraper both to remove the sheet of film from the drum and to keep the drum free from dust and dirt.
  • both functions were performed separately, for example by a separate set of individual removal scrapers (preferably made of plastic and arranged next to one another on one and the same axial line) and by a continuous cleaning scraper (preferably made of metal and extending over the entire drum width).
  • Figure 4 shows an example of a local cross-section through a drum 20 having drum outer casing 21 and a removal scraper 81 having several components 82-83 of a scraper holder.
  • the drum is supported at the side edges by two flanges made of hard fabric (for example, EPRATEX from Eriks), this being because of its heat-resistant and insulating properties.
  • Said flanges are provided with shaft ends made of stainless steel or RVS (limitation: heat losses).
  • Said shaft ends are mounted in rolling bearings, one bearing being fixed (preferably at the motor side) and the other bearing being laterally displaceable in order to absorb thermal expansion of the drum.
  • a heat-resistant grease such as, for example, BarriertaTM type 55/2, is used to lubricate said bearings in a preferred embodiment of the present invention.
  • BarriertaTM is a registered trademark of Klueber Lubrification, D 8000 Munich and comprises a temperature-resistant lubricant based on perfluoroalkyl ether).
  • Figure 8 shows a preferred embodiment of a belt path having proportional control.
  • a tension roller or control roller 36 is arranged movably in a shackle bearing 26 and can be displaced by means of a threaded spindle 27 and a screw motor 28. This is controlled in turn by (for example, two) position sensors which detect the run of the belt 41.
  • control systems such as an eccentric, an electromagnet, a pneumatic or a hydraulic cylinder, which are in turn controlled by a two-point control or by a proportional control, are, of course, also conceivable.
  • means are also provided for switching over the image side of the image material, that is to say thermal processing of said image material with the emulsion side in contact with the heated drum, instead of the rear side.
  • both temperature profiles can be controlled independently of one another and, in addition, are controlled (or managed) in such a way that both temperature profiles are substantially flattened.
  • the system comprises at least one body of revolution 20 having an outer casing 21 made of thermally conducting material (for example, a metal, for example anodized aluminium) having axial or lateral end faces 22-23 made of thermally insulating material, and having electrical heating means 60.
  • thermally conducting material for example, a metal, for example anodized aluminium
  • a special feature of this first embodiment is precisely that the axial end faces 22-23, also referred to as side faces or flanges, are thermally insulated from the remaining construction (including outer casing and shaft ends).
  • said end faces are made of "hard fabric”.
  • FIG. 12.1 shows a diagrammatic view of a so-called “segmented drum”
  • Figure 12.2 shows diagrammatically a photothermographic material (m) which can be used in the present invention.
  • drum 20 actually comprises three sections, namely a centre section 21', a left-hand section 22' and a right-hand section 23'.
  • the extremities 22 and 23 of said side sections 22' and 23' are additionally well insulated in order to limit heat losses via the flanges or via the shaft ends.
  • Running over the drum 20 (for example, having a diameter of 198 mm, a wall thickness of 14 mm and a shaft length W 490 mm) over a certain contact angle ⁇ (for example, 180°) is a conveyor belt 41 (for example, having a length of 890 mm and a width of 470 mm).
  • Such belts may be composed of metal (for example of a stainless steel), possibly covered by a fine layer of rubber, or of a plastic sheet based on a polyester film, such as Mylar (registered Du Pont trademark) or a polyimide film such as Kapton (registered Du Pont trademark).
  • An electrically resistant heating element is preferably used as heating means.
  • thermocouples Pt100 mounted in the wall of the drum is at least one, but most preferably, a plurality of temperature sensors (for example, four thermocouples Pt100) (cf. Figure 9), most preferably at various tangential points (for example, displaced through 90° with respect to one another) and at various axial points, possibly also at various depths in the drum wall thickness.
  • slip contacts are part of the prior art, so that they are not elaborated on.
  • attention is drawn to a preference for slip rings having a rhodium coating because of two special advantages: such slip contacts give (i) a reproducible signal and (ii) a maintenance-free service life of at least one million revolutions.
  • an optical interface may, if desired, be used.
  • heating element a so-called flexible or a curved heating element is preferably mounted in the inside of the drum, for example bonded with RTV adhesive ("room temperature vulcanization", obtainable, inter alia, from Dow Corning).
  • RTV adhesive room temperature vulcanization
  • Used as heating elements are, inter alia: (i) an "etched foil flexible heater” from WATLOW having a rated power of 1500 W at 240 V, or (ii) a "wire-wound flexible heater” from ELMWOOD having a rated power of 1300 W at 240 V.
  • a control circuit 70 having a PID (proportional + integral + derivative) controller 73 namely a configuration having an SW controller around a microprocessor 72 (for example, a processor 80186 of the IntelTM type) is chosen for controlling the temperature of the drunk.
  • the fed back signal 75 from a calibrated temperature sensor 68 (for example a Pt100 having an accuracy of 0.1°C within the calibrated working range) is converted and an ADC analogue-to-digital converter 76 into a binary signal 77 (for example, a 10 bit signal.
  • a differential amplifier 72 In a differential amplifier 72, a comparison is made between the digital value of the entered (or desired) target temperature 71 and the digital value of the (actual or) measured temperature 77.
  • a PWM (pulse-width-modulation) 74 is created in the microprocessor in order to control the heating element(s) 60 with a control signal 78 from the mains with so-called solid state relays (SSRs). For example, a period of 1 sec and a duty cycle ⁇ adjustable in one hundred steps from 0 to 100%.
  • SSRs solid state relays
  • FIG 11 shows a series of activation pulses having a relatively high duty cycle ⁇ .
  • the period (t s ) comprises an active time (t son ), for example a time during which a heating element is activated and can therefore heat up, and a passive time (t s - t son ), for example a time during which a heating element is not activated and can therefore cool.
  • the duty cycle ⁇ is the ratio of an active pulse width (t s on ) to the total period (t s ).
  • the duty cycle ⁇ can be varied while retaining a constant period (t s ) but with varying activation time (t s on ).
  • the duty cycle ⁇ can be varied, with the period (t s ) being varied with constant (t s on ).
  • a number of criteria for example, control parameters such as gain, integration time, differentiation time constant, filtering input signal
  • control parameters such as gain, integration time, differentiation time constant, filtering input signal
  • measurements such as percentage duty cycle, PID variables, temperature, speed
  • PT1000 sensors instead of PT100.
  • Said PT1000 sensors have the advantage that the sensitivity to the transfer/transition resistance of the slip contacts drops by a factor of 10.
  • a filter may be used, for example a "software filter”.
  • Another possibility of transmitting signals in a contact-free manner makes use of optoelectronics, for example using emitter-sensor systems.
  • thermocouples which, on receiving infrared, generate a thermal voltage. They receive the heat by radiation, so that no slip contacts are necessary.
  • sensor types are preferably used which are calibrated at 120°C, i.e. the linear portion of their characteristic is centred around 120°C or 393 K.
  • the system comprises a heating element having power compensation at the side edges (see Figure 7), which offers possibilities for an axial compensation.
  • drum 20 actually comprises, for example, three sections
  • said side sections 63 and 64 of heating element 61 have a different electrical power from the centre section 62, which is sometimes referred to as “segmented heating" system.
  • said side zones 63-64 are geometrically symmetrical with respect to the centre zone 62 and mutually identical in dimensions and in available power.
  • each zone 62-64 has a separate sensor 65-67 and a separate controller.
  • both side zones 63-64 are connected electrically in parallel and jointly controlled by one thermal probe in the centre of one of said side zones. Since the large centre zone in this example has a separate temperature probe in the drum, this actually results in two separate control circuits.
  • only one sensor is fitted and, specifically, in the axial centre of the centre zone 62 of the drum and the three zone heating systems are all three connected in parallel to one control circuit 70, but the installed powers differ for the centre zone with respect to the side zone.
  • the installed powers can, in addition, be activated by software at various levels.
  • left-hand zone 63 having an installed power of 0.522 W/cm 2 and activated at 75%
  • centre zone 62 having an installed power of 0.492 W/cm 2 and activated at 90%
  • right-hand zone 64 having an installed power of 0.522 W/cm 2 and activated at 80%.
  • Figure 15 shows a hardware possibility comprising a drum-shaped heating body 20 having, in the axial direction, three different installed powers P1-P3 in heating elements 61 (with terminals Mi-Ni).
  • heating zones can also be used, with or without symmetrical heating.
  • the heating element has a continuously extending power profile to compensate for possible static and dynamic interferences in said temperature profiles.
  • Figures 12.1-12.3 illustrate some comparative tests.
  • Figure 12.3 compares density profiles measured on image materials developed according to the state of the art, with hardware compensation (HW) according to the present invention or with hardware and software compensation (HW & SW) according to the present invention.
  • Curve 91 shoes a so-called “natural profile”
  • curve 92 shows an axial hardware-compensated profile obtained with a so-called “segmented drum and segmented heating system”
  • curve 93 shoes a further optimization using a differentiated software control of the side zones of the heating element. This reveals a clear quality advantage (with regard to density uniformity) of the present invention.
  • said heating unit Owing to the embodiment described of the body of revolution (with a “segmented drum”) and of the heating means (with a “segmented heating system”) we can specify said heating unit more precisely as a heating unit in which said heating means have a first power profile (Pa) in the axial direction with a modification of said body of revolution according to a first temperature profile (Ta), or also as a heating unit 4 in which said heating means 60 have, in the axial direction, a first power profile (Pa) which is controlled by said control means 72-74.
  • the system comprises a very specific control system in order to obtain a better response to interferences due to the sheets of film being passed through.
  • FF feedforward
  • FF-SW feedforward in software
  • Figure 10 shows a time diagram for a compensation of the tangential temperature profile. That the time patterns in Figure 10 (for example, more in the region of seconds or fractions of seconds) are in principle an order of magnitude longer than those in Figure 11 (for example, more in the region of milliseconds) is shown in the drawings by two different hatchings (vertical as against horizontal).
  • the drum is then kept by the controller at a standby temperature (see time interval SB from t0 to t1, with a duty cycle ⁇ sb).
  • signal "DET IN” assumes, for example, a logic 1 state (say, a higher voltage).
  • At least one of said detection signals DET IN or DET OUT remains high, the heating being activated with a duty cycle ⁇ dev and as a function of the measured temperature (cf. controller, Figure 9).
  • a specific preheating can already occur (see signal FF during t5 to t6 with a duty cycle ⁇ ff of, for example, 100%). After the elapse of said FF time, the controller may still be blocked at a lower duty cycle ⁇ 1 to avoid any temperature shocks.
  • a second version is provided with a feedforward in hardware (FF-HW).
  • FF-HW feedforward in hardware
  • an additional heating element for example, of 400 W which additionally heats only the drum segment which will be cooled by the film fed in. This takes place in such a way that the heat distribution over the entire drum circumference remains constant (in contrast to the main heating, which always heats the entire drum).
  • Said additional heating element may be a halogen lamp or another heat radiator (such as a ceramic element) which is arranged in a stationary manner outside the drum (see also ref 69 in Figure 3) or an additional heating resistor inside the drum (see also ref 69 in Figure 15); preferably said additional heating element has an adequately high response speed.
  • one lamp having different segments is used.
  • the hardware feedforward lamp is closed off in a light-tight manner towards the interior of the processor by means of a VITONTM rubber seal (VITONTM is a registered trademark of the company Du Pont and comprises a heat and chemical-resistant fluorinated elastomer).
  • VITONTM is a registered trademark of the company Du Pont and comprises a heat and chemical-resistant fluorinated elastomer.
  • said sealing is carried out by means of horse-hair brushes.
  • the temperature of the drum is not measured so much in the rotating drum but at a fixed point at the inlet of the processor.
  • the hardware FF can be implemented by pressing one or more small heated rollers against the drum.
  • the present invention therefore comprises a heating unit comprising a body of revolution having an electrically resistant heating element, drive means for rotating said body of revolution in a controlled manner, transport means for transporting a photothermographic material in a controlled manner around said body of revolution, heating means for heating said body of revolution in a controlled manner by means of said heating element, and means for determining, on said body of revolution, a temperature variation in the axial direction (a) according to a first axial temperature profile (Ta) and a temperature variation in the tangential direction (t) according to a second or tangential temperature profile (Tt), characterized in that both temperature profiles (Ta, Tt) can be controlled independently of one another (in the meaning of measurable and influenceable or manageable).
  • the present invention also provides dynamic corrections or compensations.
  • at least two heating zones are provided, of which the power is individually modified, for example by means of modified software, every time a sheet of film arrives.
  • Each axial and/or tangential heating zone is activated and/or compensated in a differentiated manner.
  • initially different power may be provided (cf. Figure 7).
  • dynamic state there is, in addition, the possibility of different activation by means of a variable duty cycle ⁇ (see Figure 17).
  • such compensation can also be implemented by means of variable pulse numbers or even by means of a variable phase (by gating of a sinusoidal alternating voltage by means of a thyristor).
  • An off-line compensation will primarily compensate for systematic variations in the thermal properties of a drum.
  • An on-line (or "instant") compensation will primarily compensate for dynamic variations in the thermal properties of a drum.
  • Figure 16 shows an embodiment of a drum, in which various powers (see P1,1 - P1, 2 - P1,3 up to and including Pm,n) can be switched on by hardware both in the axial direction and in the tangential direction (cf. heating elements 61 having terminals Mij-Nij).
  • said heating unit more precisely as a heating unit in which said heating means have, in the tangential direction, a second power profile (Pt) with a modification according to said second temperature profile (Tt) of said body of revolution, or also as a heating unit 4 according to one of the preceding claims, said heating means 60 having in the tangential direction a second power profile (Pt) which is controlled by said control means 72-74.
  • the present invention furthermore comprises a development apparatus 1 for developing photothermographic material, at least one feed unit 2, a development unit 4 an an unloading unit 6, characterized in that said development unit 4 comprises a heating module in the form of a body of revolution or drum 20.
  • the present invention also comprises a registration system 1 for registering photothermographic material, having at least one feed unit 2, an exposure unit 3, a development unit 4 and an unloading unit 6, characterized in that said development unit comprises a heating unit in the form of a body of revolution or drum.
  • the tests took place especially around an optical density equal to 1 on the image-forming element because the human eye is particularly sensitive in this region to small variations in density.
  • the density measurements were carried out with a MACBETHTM TD904 densitometer having an ortho-filter.
  • Figure 13 shows a tangential density profile measured on a thermographic material developed according to the second embodiment of the present invention.
  • Figure 14 shows an axial density profile measured on a thermographic material developed according to the third embodiment of the present invention.
  • a heating unit having means for developing a photothermographic material at a qualitative high level by supplying a well-defined amount of heat for a well-defined time.
  • the most important advantages of the present invention succeed in (i) achieving a very constant temperature across the entire surface of a sheet of film both across the surface of one complete sheet of film and across different sheets of film, (ii) the achievement of a very constant development time, which is constant for every point in one (or more) surface(s) of sheets of film and (iii) the achievement of very short recovery times.
  • Temperature profiles Hardware compensation Software compensaton Ta Switch on locally varying power (segmentation) Activate locally differentiated power (e.g. duty cycle) See Fig. 7, refs. 62-64; Figs. 15 & 16, refs. P1-P3 See Fig. 17 Tt Switch on additional heating means temporarily (e.g. lamp, roller) Activate differentiated power temporarily See Fig. 3, ref. 69; Fig. 15, ref. 69; Fig. 16, refs P1,1 & Pm,1 See Fig. 10, ref. 79; Fig. 17
  • the present application therefore protects also a development apparatus 1 for developing photothermographic material at least comprising a feed unit 2, a development unit 4 and an unloading unit 6, characterized in that said development unit comprises a heating unit as described above.
  • a further aspect of the present invention protects a registration system 1 for registering photothermographic material, at least comprising a feed unit 2, an exposure unit 3, a development unit 4 and an unloading unit 6, characterized in that said development unit comprises a heating unit as described above.
  • said exposure unit 3 and said development unit form one common unit around one and the same body of revolution.
  • the present invention protects a method for registering information on photosensitive and thermally developable image material, comprising the following steps:
  • said temperature variations can also be determined on the basis of only one sensor in the axial direction and one sensor in the tangential direction, or even from one single sensor which is then used for both directions.
  • the corresponding temperature variations can be derived from the electronic memory. This principle is successful both in the axial and tangential direction, but in the tangential direction an alternative can also possibly be used by means of "time sampling".
  • a further preferred embodiment therefore comprises a method which also comprises a step for the preceding determination of said temperature profiles.
  • Yet a further preferred embodiment relates to a method such as that just described, but in which exposure and development of said (image) material take place around one and the same body of revolution.
  • control parameters may change as a consequence of the error found.
  • the sheets of film to be processed are already heated before they are fed into the processor. As a result the thermal shock in the processor and the temperature drop across the drum are reduced.
  • the belt is heated.
  • said image-forming element may not have a sheet form but a belt form.
  • the film is preferably transported by means of a concomitantly rotating conveyor belt 41 which presses the film against the hot drum 30.
  • a concomitantly rotating conveyor belt 41 which presses the film against the hot drum 30.
  • the conveyor belt can itself be omitted and, for example, the tension on the film can provide for a good contact and for a satisfactory development.
  • a particular property of the present application is based on the fact that the thermal processing can take place in one of the following two divergent manners, namely (i) with the emulsion side of the image material in contact with the heated drum or (ii) with the emulsion-free side of the image material in contact with the heated drum.
  • the first method has the advantage that lower development temperatures and/or shorter development times are possible.
  • the second method has the advantage that any temperature differences are also averaged out by the base of the photosensitive layer.
  • some practical interventions have, however, to be performed (for example adjustment of temperatures and/or times, reversal of film run ).
  • a system may also comprise more than one heating body, for example a linear iteration of one and the same basic concept (two drums arranged on one side and in series after one another along a path followed by the image-forming element) or an iteratively alternating arrangement with two drums opposite one another on either side of a path followed by an image-forming element (with possibly two sides to be developed or to be dried).
  • more than one heating body for example a linear iteration of one and the same basic concept (two drums arranged on one side and in series after one another along a path followed by the image-forming element) or an iteratively alternating arrangement with two drums opposite one another on either side of a path followed by an image-forming element (with possibly two sides to be developed or to be dried).
  • Double-sided arrangement of two drums may be attractive, inter alia, in systems having a photosensitive layer on both sides of a base or having a photosensitive layer on one side of a base and an auxiliary layer (for example, an anti-halo layer or an anti-stress layer) on the other side of said base.
  • a photosensitive layer on both sides of a base or having a photosensitive layer on one side of a base and an auxiliary layer (for example, an anti-halo layer or an anti-stress layer) on the other side of said base.
  • said image-forming element comprises a photothermographic material.
  • said photothermographic materials comprise a silver halide or a mixture of silver halides, one or more organic salts and one or more reducing agents. After exposure and development, visual densities greater than 1 are obtained.
  • said silver organic salt is silver behenate and said reducing agent is a phenolic reducing agent.
  • said photothermographic materials comprise one or more toning agents which result in a neutral grey density on development.
  • said photothermographic materials preferably comprise one or more stabilizers to maintain the quality of the image formed.
  • the present invention can be used to produce both images in reflection (based, for example, on paper, inter alia, used in the copying sector) and images in transparency (based, for example, on black-and-white or coloured film, inter alia, used in medical diagnoses).

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Photographic Developing Apparatuses (AREA)
EP98203612A 1997-11-05 1998-10-17 Photothermographic development system Withdrawn EP0915395A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
BE9700883 1997-11-05
BE9700883A BE1011530A4 (nl) 1997-11-05 1997-11-05 Fotothermografisch ontwikkelsysteem.

Publications (1)

Publication Number Publication Date
EP0915395A1 true EP0915395A1 (en) 1999-05-12

Family

ID=3890816

Family Applications (1)

Application Number Title Priority Date Filing Date
EP98203612A Withdrawn EP0915395A1 (en) 1997-11-05 1998-10-17 Photothermographic development system

Country Status (2)

Country Link
EP (1) EP0915395A1 (nl)
BE (1) BE1011530A4 (nl)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1598698A1 (en) * 2004-05-21 2005-11-23 Konica Minolta Medical & Graphic, Inc. Heat developing apparatus and heat developing method
US8660414B2 (en) 2010-11-24 2014-02-25 Carestream Health, Inc. Thermal processor employing radiant heater

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS58194074A (ja) * 1982-05-10 1983-11-11 Konishiroku Photo Ind Co Ltd 定着装置
JPS6155681A (ja) * 1984-08-27 1986-03-20 Fuji Xerox Co Ltd 複写機の定着装置
EP0534417A2 (en) * 1991-09-24 1993-03-31 Canon Kabushiki Kaisha Image heating apparatus with multiple temperature detecting members
US5402211A (en) * 1992-10-21 1995-03-28 Ricoh Company, Ltd. Heated fixing roller with selectively heatable portions
EP0693716A2 (en) * 1994-07-22 1996-01-24 Canon Kabushiki Kaisha Fixing device
WO1997013181A1 (en) * 1995-10-06 1997-04-10 Minnesota Mining And Manufacturing Company Thermal processor with air flow preventing structure

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS58194074A (ja) * 1982-05-10 1983-11-11 Konishiroku Photo Ind Co Ltd 定着装置
JPS6155681A (ja) * 1984-08-27 1986-03-20 Fuji Xerox Co Ltd 複写機の定着装置
EP0534417A2 (en) * 1991-09-24 1993-03-31 Canon Kabushiki Kaisha Image heating apparatus with multiple temperature detecting members
US5402211A (en) * 1992-10-21 1995-03-28 Ricoh Company, Ltd. Heated fixing roller with selectively heatable portions
EP0693716A2 (en) * 1994-07-22 1996-01-24 Canon Kabushiki Kaisha Fixing device
WO1997013181A1 (en) * 1995-10-06 1997-04-10 Minnesota Mining And Manufacturing Company Thermal processor with air flow preventing structure

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 10, no. 220 (P - 482) 31 July 1986 (1986-07-31) *
PATENT ABSTRACTS OF JAPAN vol. 8, no. 42 (P - 256)<1479> 23 February 1984 (1984-02-23) *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1598698A1 (en) * 2004-05-21 2005-11-23 Konica Minolta Medical & Graphic, Inc. Heat developing apparatus and heat developing method
US7283144B2 (en) 2004-05-21 2007-10-16 Konica Minolta Medical & Graphic, Inc Heat developing apparatus and heat developing method
US8660414B2 (en) 2010-11-24 2014-02-25 Carestream Health, Inc. Thermal processor employing radiant heater
US9372390B2 (en) 2010-11-24 2016-06-21 Carestream Health, Inc. Thermal processor employing radiant heater

Also Published As

Publication number Publication date
BE1011530A4 (nl) 1999-10-05

Similar Documents

Publication Publication Date Title
KR930011439B1 (ko) 화상 정착장치
US7778582B2 (en) Image heating apparatus with frame accommodating apparatus components
US7427727B2 (en) Fixing apparatus and an image formation apparatus
US7548718B2 (en) Fixing device for fixing an unfixed toner image on a recording medium and image forming apparatus including the fixing device
EP0390168B1 (en) An image fixing apparatus
CN100385349C (zh) 加热装置
US5660750A (en) Image heating apparatus with elastic heater
US20060093416A1 (en) Fixing device and image forming apparatus having the same
EP0915395A1 (en) Photothermographic development system
US7190915B2 (en) Image forming apparatus with time interval control of fixing unit and control method therefor
US11402775B2 (en) Image heating apparatus and image forming apparatus
US6704526B2 (en) Image heating apparatus adapted for cleaning of speed detection mark
KR940010610B1 (ko) 가변설정온도 영상정착장치
US5592277A (en) Image fixing apparatus and image forming apparatus
JPH02253282A (ja) 定着装置
JP2004247307A (ja) 加熱器の温度制御システム
JP2006010943A (ja) 加熱装置
JP2698494B2 (ja) 像加熱装置
JPH10198214A (ja) 画像形成装置
JP3269354B2 (ja) 画像形成装置の定着装置
JP3391949B2 (ja) 像加熱装置
JP3799296B2 (ja) 画像形成装置
JPH06345292A (ja) 加熱装置及び画像形成装置
JP2023138285A (ja) 加熱装置、定着装置及び画像形成装置
JP2004029233A (ja) 定着装置および画像形成装置

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): BE DE FR GB

AX Request for extension of the european patent

Free format text: AL;LT;LV;MK;RO;SI

17P Request for examination filed

Effective date: 19991112

AKX Designation fees paid

Free format text: BE DE FR GB

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: AGFA-GEVAERT

17Q First examination report despatched

Effective date: 20020315

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20020716