US3036494A - Photographic color printer - Google Patents

Description

May 29, 1962 R. WlCK 3,036,494

I 'PHOTOGRAPHIC COLOR PRINTER Filed Dec. 31, 1957 INVENTOR.

Richard W/CK BY 3 Sheets-Sheet 1 Adm [#7 4 Maw Ma 29, 1962 R WICK 3,036,494

PHOTOGRAPHIC COLOR PRINTER Filed Dec. 31, 1957 3 Sheets-Sheet 2 8fib INVEN TOR. Richard WICK BY 3,036,494 PHOTOGRAPHEC COLOR PTER Richard Wick, Munich, Germany, assignor to Agfa Aktiengesellschaft, Leverkusen-Bayerwerk, Germany Filed Dec. 31, 1957, Ser. No. 706,464 Claims priority, application Germany .lan. 12, 1957 11 Claims. (Cl. 88-24) The present invention refers to photographic printer devices, and more specifically to devices of this kind adapted to reproduce color transparencies by photoprintmg.

It is a requirement in this art that the total exposure be carried out in an automatic sequence of partial exposures, that the individual exposures are automatically controlled by suitable means, and that the alternatively operative elements used for carrying out the partial exposures, preferably the various color filters introduced into the path of the printing light, be controlled automatically by other suitable means.

As far as is known, in the past attempts have been made to provide for a purely mechanical control of the sequence of the various operations of the diversified elements of the color printing apparatus, e.g. by means of cam shafts operating a number of electric switches, but devices of this type were found unsatisfactory because of their quite involved structure and delicate maintenance, their considerable cost and certain inconvenient characteristics like vibrations caused by the driving motor and the inevitable noise developed by drive and power transmission to the switch actuators.

It is a main object of this invention to avoid all the drawbacks of known equipment by providing a compact, simple and reliable apparatus of comparatively low cost, and of vibration-free and noiseless operation.

With above object in view, a photographic printer according to the invention for reproducing an image from a transparency by a sequence of partial exposures on photosensitive material comprises, in combination, a combination of means for carrying out a plurality of partial exposures in a predetermined sequence and with predetermined exposure times depending upon the density of said transparency, and with selected modification of light for each partial exposure; circuit means interconnecting said means for electrically operating the same; and relays connected in said circuit means for automatically controlling the operation of all of said means.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a diagrammatic elevation, partly sectional, of an embodiment of the invention;

FIG. 2 is a circuit diagram showing part of the electrical means incorporated in the embodiment of FIG. 1;

FIG. 3 is another circuit diagram showing another part of the electrical means; and

FIGS. 4, 5 and 6 illustrate diagrammatically certain parts of the circuit of FIGS. 2 and 3 in various operational positions.

Referring to FIG. 1, a photographic enlarger has a base 1 assembled with a column 2 along which the actual enlarger head 3 is slidably or adjustably guided and supported. Comprised in the head 3 is the printing light source 4, an optical condenser 5, a heat-protection filter 6, a mirror 7, a negative carrier 8 and the projecting objective 9. Focussing means and other details not forming part of the invention are omitted from the drawing. On the base 1 rests a copying frame it) which is equipped with a translucent screen 11 for focussing, an inner reflector 12 and a photo-cell 13 which forms part of an exposure control device described further below. The reflector 12 serves to reflect the light rays coming from the source 4 and passing through sensitive paper placed on the translucent screen 11 and through the latter,

' towards the photo-cell 13.

Accommodated within the enlarger head 3 are also a blue filter 14, a green filter 15 and a red filter 16, each of which is held in a corresponding filter holder 17, 18, 19, respectively, supported for sliding movement in a direction perpendicular to the direction of the axis of the beam of light between the mirror 7 and the frame 10. There are further in the head 3 a set of solenoids 20, 21, 22 which are designed to cooperate with the respective armature members 23, 24, 25, attached to the filter holders 17, 18, 19, respectively, so as to move any one of them individually against the action of respectively attached return springs 26, 27, 28 into a position in the path of said beam of light, whenever any one of said solenoids is actuated electrically in a manner and by means described below.

FIGS. 2 and 3 illustrate the electric circuits used for controlling both the exposure and the interposition of the color filters between light source and negative.

The photocell 13 is preferably a photo-multiplier tube which is connected to the secondary winding of the line supply transformer 33 via a high-voltage transformer 29 and the alternatively connectible control Potentiometers 3t 31, 32, respectively. In circuit with the cell 13 is the timing condenser 34 which in turn is in circuit with the grid of a tube 35. In the particular example of an embodiment of the invention the tube 35 is a cold cathode thyratron. The anode potential is furnished from another line transformer 36 and a rectifier arrangement 37. Connected in the anode circuit of the tube 35 is a relay coil 38 adapted to operate the switches 38a, 38b (FIG. 2) and sac (FIG. 3). Connected in parallel with the tube 35 is the start switch 3?. The secondary winding 40 of the transformer 36 furnishes energy to the solenoids 20, 21, 22, respectively.

It should be noted that the circuits of FIGS. 2 and 3 are actually one circuit since the respective terminals 41 and 42 are to be considered as being permanently connected. The terminal 42 in both FIGS. 2 and 3 represents ground. The circuit portion of FIG. 3 contains the relay coils 43, 44, which are to control the operation of the color filters 14, 15, 16, respectively, and of the control potentiometers 36, 31, 32, respectively. The relay coil 43 operates the switch 43a in the circuit of solenoid 20, and the switch 43b in the circuit of potentiometer 30. In a similar way the relay coil 44 is associated with switches 44a, 44b, and relay coil 45 is associated with switches 45a, 4512, said switches being analogously associated with the solenoids 21, 22, respectively, and with solenoids 31, 32, respectively. Condensers 46, 47, 48 are respectively connected in parallel with the relay coils 43, 44, 45, respectively.

The circuit portion of FIG. 3 shows also two coils 49,

aces r94.

50 each constituting a flip-flop relay operating in such a manner that when the relay is energized the associated switches are moved from one into the other position thereof, but do not return into the previous position when the energization of the relay is discontinued. These relay switches are only returned to a previous position when the relay is again energized. The flip-flop relay coil 49 is connected between the feed line 51 and the stationary contact 52 of the change-over switch 380, while the flipflop relay coil 50 is connected directly between the lines coming from the terminal-s 41, 42, respectively, i.e. between feed line 51 and ground. The relay coil 49 operates the switch 4% located in series with the relay coil 50, and the change-over switch 4% to whose stationary contacts the lines 53, 54, respectively, are connected. The relay coil 5% operates the switches 59a, 50b which are connected with the abovementioned line portions 53, 54, respectively, and cooperate with stationary switch contacts 55, 56, 57., respectively, associated with the relay coils 43, 44, 45, respectively, as shown in FIG. 3.

Between the switch 4% and a line portion 58 connected to the stationary contact 59 of the change-over switch 38c are connected, in series with each other, the relay coil 60, the thyratron 61 and a resistor 62 constituting a delay circuit. In a circuit in parallel with the means 66, 61, 62 are connected a charging condenser 63, which is connected to the grid of tube 61, and a charging resistor 64-. In parallel with the relay coil 60 and the thyratron 61 is connected a resistor 65. Of course, the cathode heating means 66 of the thyratron 61 is connected to the secondary winding 4% of the transformer 36 although this is not indicated in the diagram.

The relay coil 60 operates the switch 6% for disconnecting the resistor 65, the switch 6% for shortcircuiting the condenser 63, the switch 600 (FIG. 2) for switching-on the printing lamp 4, and the switch 6% (FIG. 2) which is connected in parallel with the timing condenser 64 of the exposure control device.

In practice the whole arrangement operates as follows:

Before starting operation all parts and elements of the arrangement are in position of rest, i.e. in the positions shown in FIGS. 1-3, and the whole circuit is without energy, but the grid of the thyratron 35 which ignites only at a higher grid potential, has the same-potential as the cathode, while the anode of the thyratron 61 is without any potential because it is disconnected on account of the position of the switches 49b, 50a and 5012 as shown in FIG. 3.

While the manual light control switch 67 is left in open position the automatic light control arrangement is switched-on by actuation of the push-button switch 39. This energizes the relay coil 38 so that the switch 38a is closed, the switch 38b is opened and the switch 38c is moved from contact 59' to contact 52. However by opening the switch 381) the relay coil 38 is again de-energized as soon as the condenser 68 which is connected in parallel with the coil 38, has discharged. Hereby the switches 33a, 38b, 360 are returned to their position of rest. The condenser 69 being in parallel with a high-ohmic resistor 70 prevents immediate, unintended re-energization of the coil 38 in case the push-button is held in pressed-down position longer than necessary.

During the short period of switch 380 being in the position of contacting the contact 52, the flip-flop relay coil 49 has been energized briefly whereby the switch 49a has been closed and the switch 4% has been changed to establish connection with the line portion 53. For the reasons set forth above, the last mentioned switches remain in the now obtained positions even after the relay coil 49 has been de-energized. On account of closing the switch 4911 also the flip-flop relay coil 50 has been energized whereby the switch 50a has been changed from contact 57 to contact 55, and switch 59b has been closed, a condition which is clearly illustrated in FIG. 4. Hereby the relay coil 43 is energized via line portion 53, resistor 65,

4 switch 60:: and resistor 62., and at the same time the switches 43a, 43b are closed. In'this manner the solenoid 2A) is energized and the associated blue filter 14 is moved into position across the path of the light beam of the not yet-switched-on lamp 4, while simultaneously the corresponding control potentiometer 34 is connected into the primary circuit of the high-voltage transformer 29.

In addition, the energization of the relay coil 43 causes the thyratron 6 to obtain anode potential while the condenser 63 is charged via the resistor 64. As soon as the condeuser63 and accordingly the grid of tube 61 (which grid had originally negative potential relative to the cathode) have reached a predetermined potential the tube 61 ignites. Then the relay 6i) is energized, the switch 60a is opened so as to cut out the resistor 65, the switch 631; is closed so as to discharge the condenser 63, the switch 600 is closed so as to switch-on the printing lamp 4, and finally the switch 60d is opened. In this manner the exposure of the sensitive paper assumed to be placed on the surface of the screen 11, for the color blue is started.

The blue printing light passing through the filter 14and through the color negative reaches the photocell 13 and generates therein a current the strength of which depends upon the proportional blue-content and upon the density of the negative, and which now charges the timing condenser 34. As soon as this condenser and accordingly the grid of the tube 35 have reached a predetermined potential, the tube 35 ignites so that the relay coil 38 is again energized. Consequently the switches 38a, 38b, 380 are again moved into their respective second positions, but are returned to the previous position immediately after discharge of condenser 68 due to the interruption of the anode current of tube 35 by switch 38b. On account of the switch 330 having been moved for a brief period into its second position, the flow of currentthrough the tube 61 and relay coil 60 is also interrupted so that the switches 6%, 6% are again closed, the switches 6017, one however are again opened. Hereby the printing lamp 4 is again switched oif and the blue-exposure is terminated and completed. The timing condenser 34 is also discharged again.

As can be seen, due to the above mentioned moving of switch 38c for a brief period into its second position, the flip-flop relay coil 49 has again received a brief current impulse whereby the switches 49a, 4% have been returned into their initial position so that the flip-flop relay coil Si) is de-energized but the switches 59a, 50b remain in connection with their contacts 55 and 55, respectively, as is shown in FIG. 5. Consequently the relay coil 43 is de-energized and the blue filter 14 is removed from its position across the light path (under the action of the associated return spring 26) and the control potentiometer 30 is also switched off. Meanwhile the relay coil 44 has been energized via the line portion 5 and the circuit containing the parts 65, 60a and 62. Consequently the switches 44a, 44b are closed, the green filter 15 is moved into the light path of the printing lamp 4 which is not yet switched on, and the potentiometer 31 is connected in circuit. In the same manner as in the above described case of blue-exposure,

after a certain delay caused by charging the condenser 63, the flow of current through the tube 61 and the relay coil 60 is started so that the switches 60a, 60b are again opened and the switches 60b and 600 are again closed; therefore the green-exposure" is started. It is terminated automatically in the same manner as was described for the blue-exposure, after a predetermined amount of green light has impinged upon the cell 13.

Also after the completion of the green-exposure the relay coil 38 moves the switch 382: briefly into its second position whereby the flip-flop relay coil 49 again receives a brief impulse so that the switches 49a, 49]) are again changed over into their left-hand positions, respectively, opposite to those shown in FIG. 3. Hereby the flip-flop relay coil 50 is again energized so as to move the switches 50a, 50b again into their respective right-hand positions as shown in FIG. 6. Consequently the relay coil 44 is de-energized, the green filter is removed from the light path and the potentiometer 3-1 is disconnected. Simultaneously, the relay coil 45 is energized and causes via switches 45a, 4512 the red filter 16 to be moved into the light path and the potentiometer 32 to be switched-on. The now following red-exposure is started automatically in the same manner as described above for the blueexposure and green-exposure, and after a predetermined amount of red has impinged upon the photo-cell 13 the red-exposure is automatically terminated.

Also after completion of the red-exposure the relay coil 38 moves the switch 380 once more briefly into its second position whereby the flip-flop relay coil 49 once more receives a brief current impulse that moves the switches 49a, 4% into their right-hand positions as shown in FIG. 3. Hereby the relay coil 5t) is de-energized but the switches 50a, 56b remain in the position in which they were during the red-exposure. Consequently all switches 49a, 49b, 50a, 5% have then returned into the starting position as shown in FIG. 3.

By the last mentioned movement of switches 49a, 49b, the relay 45 is de-energized so that the exposure in all three colors is completed and terminated, and the whole arrangement is entirely ready for a new cycle of operation.

It is evident that the amounts of light that are intended to impinge upon the sensitive paper can be predetermined for each color individually by correspondingly setting the respective control potentiometers 30, 31, 32.

The delay circuit consisting substantially of the components 61, 63, 64 and 66b serves to delay the switching-on of the printing lamp 4 by the action of relay coil 60, until the color filter 14, 15 or 16, as the case may be, is completely moved into position across the light path and until any vibration of the enlarger head 3 that could possibly be caused by the movement of the filters, has completely subsided. The amount of delay can be predetermined easily e.g. by properly dimensioning the resistor 64.

In a similar manner the condensers 46, 47, 48 cause a delay of the de-energization of the relay coils 43, 44, 45, respectively, and thereby a delay of the removal of the associated filters I4, 15, 16, respectively, from the light path so that an exposure of the sensitive material by white light from the after-glow of the switched-off lamp 4 after termination of the individual color exposure is safely and reliably prevented.

The cutting-out of the resistor 65 by the switch 60a which is in open position during the passage of current through the tube 61 and the relay coil 60, is intended to prevent an overload on the relay coils 43, 44, 45 while the thyratron 61 is in ignited condition.

Of course, the switches 60c and 60d of the exposure control circuit could be controlled, instead of being directly actuated by the relay coil 60, by a separate relay coil, not shown, which could be connected e.g. to the secondary winding 40 of the transformer 36 in circuit with a switch, not shown, that would be operated by relay coil 60.

'It should be noted that also the exposure control circuit, i.e. essentially the circuit shown in FIG. 2, could be modified in various Ways without departing from the basic idea of this invention.

It can now be seen clearly that the arrangement according to the invention entails the great advantage that the whole operation is made completely automatic due to the exclusive use of relays and timing means. The delay means in connection with the relays greatly increase the reliability and trouble-free operation of the color printing apparatus.

The application of the arrangement according to the invention is not limited to enlarging equipment as referred to by way of example in above description of an embodiment, but e.g. is of substantial advantage in connection with other types of photographic printing equipment in which the total exposure is composed of a plurality of partial exposures, and also in connection with contact printing apparatus. Moreover, the location of the photoelectric cell 13 is of no significance for the scope and gist of the invention. For instance, the cell could be arranged so as to be influenced not by the colored light that has passed through the sensitive material, but by the light reflected thereby. Or else, the cell could be influenced by rays of color light that are reflected by a partially transparent mirror interposed in the light path between the negative and the sensitive material.

In order to establish a predetermined relation between the photo-current and the light intensity or a certain spectrally differentiated sensitivity it may be useful to provide several photo-cells, if necessary in connection with correspondingly added switch means. Also optical scanning of the negative may be used for controlling the ex posure photo-electrically.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of photographic color printer differing from the types described above.

While the invention has been illustrated and described as embodied in automatic photographic color printer, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

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 application without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a printing apparatus for producing photographic color prints from a color transparency on light sensitive printing material by a plurality of consecutive exposures of said printing material to printing light of respectively different colors, in combination, light emitting means including color control means, at least said color contol means being movable for alternatively producing a beam of printing light of any one of a plurality of different colors adapted to pass through a color transparency; moving means for successively moving at least said color control means into operative positions respectively associated with said plurality of diiferent colors; a single exposure time regulating means, including a photoelec tric cell located in the path of said printing light, for automatically terminating each of said consecutive exposures after a duration varying in accordance with the characteristics of the transparency whenever a predetermined quantity of said printing light of a particular color involved in the respective exposure has illuminated said photoelectric cell; controlling means for automatically controlling said light emitting means in a cycle of said consecutive individual exposures of variable durations required for a complete color printing process and adapted to successively actuate said moving means and to initiate thereby consecutively said individual exposures of the respective color, said controlling means including a plurality of switch means and relay means for operating all of said switch means, respectively, said relay means being in circuit with said exposure time regulating means; and circuit means interconnecting said light emitting means, said moving means and said controlling means, and for connecting said means with a source of electric energy.

2. In a printing apparatus for producing photographic color prints from a color transparency on light sensitive printing material by a pluralityjof consecutive exposures of said printing material to printing light of respectively different colors, in combination, light emitting means for alternatively producing a beam of printing light of any one of a plurality of'diiferent colors adapted to pass through a color transparency; light selector means associated with said light emitting means, including a plurality of color filter means movable into and away from the path of said printing light, for alternatively selecting for each of a series of consecutive exposures one of said colors, respectively, of said printing light; moving means for successively moving said color filter means into and away from the path of said printing light; a single exposure time regulating means, including a photoelectric cell located in the path of said printing light, for automatically terminating each of said consecutive exposures after aduration varying in accordance with the characteristics of the transparency whenever a predetermined quantity of said printing light of a particular color has illuminated said photoelectric cell; controlling means for automatically controlling said light selector means in a cycle of said consecutive exposures of variable durations required for a complete color printing process and capable of causing the selection, for each exposure, of the respective color of printing light by actuation of said moving means and of initiating the individual exposures consecutively, said controlling means including a plurality of switch means and relay means for operating all of said switch means, respectively, said relay means being in circuit with said exposure time regulating means; and circuit means interconnecting said light emitting means, said moving means and said controlling means, and for connecting all of said last mentioned means, respectively, with a source of electric energy.

3. In a printing apparatus for producing photographic color prints from a color transparency on light-sensitive printing material by a plurality of consecutive exposures of said printing material to printing light of respectively different colors, in combination, light emitting means for producing alternatively a beam of printing light of any one of a plurality of diiferent colors adapted to pass through a color transparency; light selector means associated with said light emitting means, including a plurality of color filter mews movable into and away from the path of said printing light, for alternatively selecting for each of a series of consecutive exposures one of said colors, respec tively, of said printing light; a single exposure time regulating means, including a photoelectric cell located in the path of said printing light, for automatically terminating each of said consecutive exposures after a duration varying in accordance with the characteristics of the transparency whenever a' predetermined quantity of said printing light of a particular color involved in the respective exposure has illuminated said photoelectric cell; controlling means for automatically controlling said light selector means in a cycle of said consecutive exposures of variable durations and capable of causing the selection, for each exposure, of the respective color of printing light and of initiating the individual exposures consecutively, said controlling means including electromagnetic moving means for moving said color filter means, respectively, and a plurality of main relay means having control contacts in circuit with said filter moving means, respectively, for controlling by energization of said moving means the movement of said color filter means, respectively, and individual main relay coils, respectively, connected on one side in parallel with each other to one terminal of a source of electrical energy, said controlling means further comprising three input switches, two of said input switches being connected in parallel with each other and either one being in series with the third one of said input switches, said input switches forming together input switch means connected with the other side of said main relay coils, respectively, for alternatively controlling the movements of said color filter means by energizationof saidl electrornagnetic moving means.

through said source of electric energy whenever they are to be energized; and circuitmeans interconnecting said light emitting means and saidcontrolling means, and for connecting said all of'said last mentioned means, respectively, with said source of electric energy.

4. A photographic color printer as set forth in claim. 3, including individual delay means associated and connected in circuit with said main relay coils, respectively, for delaying the de-energization of the respectively associated main relay coils after the particular main relay coil has been disconnected by operation of atleast one of said input switches.

5. A photographic color printer as set forth in claim 3, wherein said exposure regulating means includes a plurality of control potentiometers connected in circuit with said photocell and respectively associated with said plurality of color filter means, said main relay means including second relay contacts, respectively, individually associated and connected with said control potentiometers, respectively, for selectively connecting and disconnecting said potentiometers in and from the circuit of said photocell, respectively, when said main relay coils are energized and dc-energized, respectively.

6. A photographic color printer as set forth in claim 3, including a first and a second flip-flcp-relay having each a flip-flop-relay coil connected in circuit with said source, the first flip-flop-relay coil being capable of operating said two of said input switches connected in parallel with each other, and the second flip-flop-relay coil being capable of operating said third one of said input switches; and including a relay switch having contacts connected in series with said first fiip-flop-relay coil and being operable also by said second flip-flop-relay coil.

7. A photographic color printer as set forth in claim 6, including second relay means having contacts for operating said source of light and having a second relay coil arranged in series with said switch means so as to be connected in series with any one of said main relay coils by operation of said input switches.

8. A photographic color printer as set forth in claim I 7, including a first delay means connected in circuit with said switch means for delaying the starting of a partialcolor exposure in favor of completion of said movement of said color filter means caused by energization of one of said main relay coils before the start of the particular partial color exposure upon energization of said second relay coil.

9. A photographic color printer as set forth in claim 7., including a delaying circuit associated with said second relay coil for delaying the action of said second relay means until after completion of the action of said main relay means.

10. A photographic color printer as set forth in claim 9, including a second delay device connected with said exposure time regulating means for delaying said movement of said color filter means after completion of a partial color exposure in favor of complete elimination of illumination of said printing material by said beam of light after termination of an exposure by said exposure time regulating means. I

11. A photographic color printer as set forth in claim 9 including individual delay means associated and connected in circuit with said main relay coils, respectively, for delaying the de-energization of the respectively associated main relay coils after the particular main relay coil has been disconnected by'operation of at least one of of said photo-cell, respectively, when said main relay coils are energized and de-energized, respectively.

References Cited in the file of this patent UNITED STATES PATENTS 2,484,299 Labrum Get. 11, 1949 2,500,049 Williams et a1 Mar. 7, 1950 2,518,947 Simmon Aug. 15, 1950 10 Davidson Jan. 5, 1954 Curry Oct. 19, 1954 Horak Sept. 25, 1956 Gage et a1. July 1, 1958 Modney Aug. 19, 1958 FOREIGN PATENTS France Dec. 17, 1956

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