US2138445A - Photographic printing apparatus - Google Patents

Description

P.- DAUTZENBERG 2,138,445

PHOTOGRAPHIC PRINTING' APPARATUS Nov. 29, 1938.

Etta/'nc y NOV. 29, 1938. p DAUTZENBERG 2,138y445 PHOTOGRAPHIC PR INT ING APPARATUS Filed NO'V. 28, 1956 5 SheeLS-Sheefl 2 Nov. 29, 1938. DAUTZENBERG 2,138,445

v v PHOTOGRAPHE PRINTING APPARATUS Filed Nomea, 195e 3 sheets-sheet' s Patented Nov. 29,' 1938 PATENT OFFICE Paul Dautzenberg. Aachen, Germany, .assigner tov Zeiss Ikon Aktiengesellschaft, Dresden, Germuy Application November 2K8, 1936, Serial No. 113,223

, l In Germany November 30, 1935 Claims.

'I'his invention relates to photography andv more particularly to photographic printing apparatus especially adapted for single prints.

One of the objects of the invention is to prol vide photographic printing apparatus in which either-the quantity of printing light flowing in a predetermined period of time to the negative or the yperiod of exposure in photographic printing is adjusted in accordance with the transparency l()A or density of a negative to be printed so that unlform results 'are always obtained.

Another object of the invention is to provide devices for adjusting the light flowing to the neg-- ative or the period of exposure comprising a pho- 16 toelectrical-element adapted to be influenced by the printing light passing through the negative and means controlled by the current of the photoelectric-element, which means itself control a mechanism controlling the quantity of light flowing to the negative or the' period of exposure.

Other objects-and advantages of my invention will appear from the following description when read in connection with the accompanying draw-` ings. In the drawings- Fig. 1 is a vertical sectional view of one form 'of the photographic printing apparatus; Fig. 2 is a vertical sectional view along lines 2 2 of Fig. 1; Fig. 3 is a view of a modiiled form of the photoelectric-cell;

Fig. 4 is a vertical sectional view of a further modified form of the photographic printing apparatus;

- Fig. 5 is a sectional view o f the time-switchclock employed in the embodiment of the invention, shown in Fig. 4;

Fig. 6 is a vertical sectional view of another modified form;

Fig. 7 is a vertical sectional view of the timeswitch-device employed in the embodiment shown in Fig. 6 on an enlarged scale;

Fig. 8 is a detail of the clamping mechanism employed in the form of the invention, shown in Fig. 7;

Figs. 9 and 10 illustrate in plan view and elevatien view respectively a. modied form of the" clamping means for locking the pointer of the measuring instrument.`

In the embodiment of the invention shown in Figs. 1-'3 of the drawings I is a casing. This casing has a window 2 with a glass plate 3 in its `top for receiving rst the negative and afterwards the negative and the posltivesuch as a sensitized paper for the print. The negative and the positive are held in position in the known manner by a closing-cover not shown. Two lamps 4 and 5 for furnishing the printing light are adapted to be connected to a source of supply through wires 6, l, and l. A light-sensitive element 8 such as a photoelectric-cell, i. e., a selenium cell is mounted on an arm 9 journaled on the top of the casing I. The arm 9 consists of two parts connected by a.

link 9. By moving of the arm 9 about its pivotvjournal I0' the photoelectrlc-cell 8 may be. vbrought above the window 2 and away. The photoelectric-cell 8 is connected by connectors I0 and` II to a moving-coil instrument I2 having a pointer I3, a scale I4 and a contact I5. If the pointer I3 touches the contact I5 an electric circuit I6, I1. 3l is closed. An electro-magnet I8 is' arranged in this circuit. An adjustable resistance I9 is disposed in the circuit 6, "I, l' for the lamps .4 and 5. The resistance I 9 is regulated by the lever 20 having sliding contact 29. The lever 2D- is pivoted by a shaft 2I in a wall of the casing I.

' Mounted on theouter end of this shaft 2l is a handle 22 which may be locked in its initial position by the spring catch 23. lIf this catch is released, the lever 22 and thereby the lever 20 are moved to the left (Fig. 2) by the spring 24 fastened to an extension 25 of the lever 20. This spring 24 is tensioned on moving the lever 20 to -its initial position to'the right (Fig. 2). The speed of movement of the lever 20 after releasing of the catch 23, is regulated by a iluid brake comprising a cylinder 26, a piston 2I, a'nd a pistonrod 28 connected to the lever extension 25. In order to lock the lever 20 in the different positions a locking mechanism is provided comprising ratchet segment 30 fastened to the lever 20, spring pawl 3| with tooth 32, and a spring pawl 33 with hook 34 for locking the pawl 3|. If the pawl 331s released, pawl 3l meshes with the teeth of the segment 30 and thereby the movement of the lever 20 is interrupted and the lever 20 is locked in this position. Releasing of pawl 33 is obtained by energizing of electro-magnet I8. 'I'he pawl 33 forms the armature of the electro-magnet I8. Spring pawl 3l has a contact 35. In the position of the pawl 3l, in which'it is locked by the pawl 33, contact 35 touches a contact 36 mounted on a wall of the casing I. 'I'he conducting wire I'I to the electromagnet I8 is connected to the contact 36 and a wire 31 connects pawl 3l with the electromagnet I8. Therefore, if pawl 3i is released in order to lock the lever 20 the circuit l6, Il, 3l of the electro-magnet I8 is interrupted. The purpose of the adjustable resistance I9 is to control the luminous intensity of the lamps 4 and 5. Furthermore a mask 33 for regulating the quantity of light flowing from the lamps 4 and 5 to the window 2 is disposed between the lamps 4 and 5 and the window 2. 'I'his mask consists of a Venetian-blind, the blades 33' of which are rotatably mounted in arms 33 fastened to the top of the casing I. The blades 33 are rotated by drawing straps 40, 4I, and straps 42', connecting the blades 33'. The straps 4Ii and 4I are connected to the lever 20 on opposite points of its pivot-shaft 2|. But only one of the two adjusting means for the printing light is necessary either the adjustable resistance I9 for controlling the luminous intensity of the printing lamps 4 and 5 or the mask 33 for controlling the quantity of actinicvlight reaching the negative and positive. Y

In operation first only the negative, which is to be printed, is laid on window-glass 3 and the photcelectric-cell 8 is moved above the negative. At the same time the controlling lever 20, 22 for the resistance I3 and the mask 33 has been moved in its initial position (Fig. 2). After releasing of the spring catch 23, the lever 20 begins its movement to the left (Fig. 2) under the action of the spiral spring 24. During this movement of the lever 23 the lamps 4 and 5 are placed in circuit. At the beginning oi the retrograde movement of the lever 23 there exists the greatest resistance and therefore the printing lamps 4 and 5 have the lowest luminous intensity. The luminous intensity increases in accordance to the progressive retrograde movement of.the resistance controlling lever 23. As soon as the iux cf light passing through the-negative has reached a quantity which corresponds to the luminous intensity necessary for the printing,

the pointer i3 of the moving-coil-instrument I2 touches the contact I5. Thereby the circuit I3, I1, 31 is closed, the electro-magnet I3 is energized and its armature formed by the pawl 33 .is attracted. Therefore the pawl 3i is released and it meshes with the teeth of-V the ratchet segment 33. Consequently the lever 23 is locked and therefore the resistance I3 and the luminous intensity of the lamps 4 and 5 are adjusted 'accordingly. The mask 33 has been adiusted at the saine time by the lever 23. Consequently the quantity of light reaching the negative is controlled in accordance with the transparency or density oi the negative. The time of exposure is the same for each quality of paper for the print.

The time of exposure is controlled by a timeswitch-clock 42 of known construction as employed in connection with photographic printing apparatus. The electrical connection of the clock 42 with the circuit 3, 1, I for the lamps 4 and 5 is not shown.

In order to adjust the quantity of light flowing to the negative in accordance to the degree of sensitiveness of the printing paper the contact I5 of the moving-coil-irstrurnent is arranged adjustablyon the scale I4. Therefore the movement of closing the contact between the pointer I3 and the contact I5 may be varied according to the degree of sensitiveness of the printing paper. The contact takes place sooner in connection with highly sensitive printing paper and later with printing papergoi1 lower sensitiveness.

This purpose can be reached also by arranging an adjustable resistance 43 in the circuit I0, II oi the photoelectric-cell 3. VFurthermore this purpose can be obtained by combining with the phctoelectric-cell an adjustable mask 44 as tive and the whole is closed by a cover not shown.

As soon as the printing operation is nished the controlling levers 20, 22 may be moved to their initial position (Fig. 2). Hereby the teeth of the vratchet-segment 30 press back the tooth 32 and the pawl 3|, the pawl 33 locks the pawl 3i by its tooth 34 and the contacts 3l, 36 are closed. Then the apparatus is ready for a new printing operation.

The apparatus may be built in such a manner that the movement ,of the closing-cover for the negative and positive or the turning-movement of the arm 3 of the photoelectric-cell are transmitted to the controlling lever 20, 22 in order to move it in its initial position. In this case proper transmission means are arranged between the above-mentioned cover or the arm 3 and the lever 20, 22.

According to the modified form of the apparatus shown in Figs. 4 and 5 the period of exposure is controlled in accordance with the transparency or density of the negative, while the quantity of printing light passing in Itha unit of time to the negative and positive may be the same for lall negatives.

43 is the casing of the apparatus, 41 the window with the glass-plate 43 for receiving the negative and positive, which are held in position by a cover not shown. 43 and 50 are the printing lamps, 5I is the photoelectric-cell, 52 the swinging arm for the cell, which is journaled at 53 and which consists of two parts connected by link 54. 55 and 56 are the connecting wires between the cell 5I and the moving-coil-instrument 51, which has the pointer 53, the scale 58 and the adjustable contact 33. The casing 43 has a separate compartment 5I with a lamp 3i, and a window 33 with glass-plate 34 for receivingrthe negative. These parts 6I, 62, 33, 34 serve to adjust the time-switch-clock' 45. The lamp 32 is placed in circuit 31, 33.

45 is a switch-clock for controlling the period of exposure and this clock is connected electrically with the lamps 43 and 5C by wires 35 and 33. The clock is controlled by the rotating arm or pointer 12 lying on the outside of the dial 13 in the known manner. This pointer is mounted on the clock-shaft 13 and this shaft or the lever 12 is under the action of the spiral spring 13. This spiral spring 15 moves the lever 12 and the shaft 13 in a counter-clockwise direction, when the lever is released in its initial position. An adjustable resistance 13 for controlling the luminous intensity of the lamp 32 is mounted in the housing of the time-switch-clock 4l and a controlling lever 1I for the resistance I3 is mounted on the clock-shaft 13. Further a ratchet-disc 'I1 ilsmounted on the clock-shaft .13. The resistance 13 is placed in the circuit 31, 33 for the lamp 32. The levers 1I and 12 are held in their initial position by a springcatch 13, which may be actuated from theaut-V vside of the clock. The initial position, Figs. 4

form, Figs. 1 and 2, 18 is the spring pawl for meshing with the ratchet teeth of the disc 11.

'The other parts of the time-switch-clock are of known construction.

As soon as the lever 12 is released the clock shaft 18 is rotated by the spring 15 in a counterclockwise direction and thereby the resistance 10 is decreased and the luminous intensity of the lamp 62 is increased. When the light from lamp 82, reaching the cell 5| has obtained a xed degrec, the circuit 82, 83 is closed by the pointer 58 and contact 60. The period which is necessary for closing this circuit depends on the density or transparency of the negative. On closing of the circuit 82 and 83 the ratchet disc 11 and thereby the clock-shaft 18 are locked by the locking mechanism above-described. Thereby the time-switch-clock is adjusted and this clock` cony trois the period of exposure in the known manner. Evidently with negatives having higher transparency the locking oi.' clock-shaft 18 takes place sooner than with negatives having a lower transparency. Therefore the period of exposure corresponds to the degree of rotation of the clock-shaft 18 before its locking.

For the purpose or adjusting the period of exposure in accordance with the degree of sensitiveness of the printing material (paper), an adjustable resistance may be placed in the circuit of the photoelectriccell or an adjustable mask may be mounted on the photoelectric-eell in the same manner as shown in connection with Figs. 1-3.

In the modified form shown in Figs. 6, rl and 8 the time of exposure is controlled in accordance with the transparency or density of the negative. 88 is a casing containing a lamp 81, a window 88 and glass-plate 89 for receiving the negative or the negative and the positive, held in position by a cover not shown. 80 is the photoelectric-cell, mounted on a swivel arm 9|,

adapted to swing the cell 90 above the window spring |I.

88 and away. Electrical wires 92, 93 lead to the moving-coil-instrument 94, shown in broken lines. -This moving-coileinstrument is combined with a` time-switch-elock 95, which controls the time of exposure. The pointer or lever 95' of the moving-coil-instrument can be locked in different positions by two clamping jaws 98 and 91 of semi-circular shape. These 'clamping jaws 99 and 91 are rotatablymounted on horizontal stubaxies 98 and 99 and the jaws are opened by a Bowden-cable |00 and they are closed by a spiral The Bowden-cable |00 is led to the casing of the photoelectric-cell 90 and |02 is a push for the Bowden-cable. In the openedposition the pointer 95' can swing between the two jaws 9B and 91. When the pressure on the push |02vis released, the jaws 96 and 81 move to closed position and the pointer is locked in its position. |03 is the casing -of the time-switch-clock. A slide-bar |04 with push-button |05 is mounted in the top of the casing andthe bar |04 is adapted to be moved up. by Aa spiral sring |05 and down against the tensionv ofv the spring |05..

.of the strap H8.

|08 and |01 are two noses, movably mounted on the slide-bar. These noses are under the action of spiral springs |08-and |09. ||0 isa turning switch and and ||2 are electrical wires leading to the circuit for the lamp 81. A brake lever III is mountedon ashaft ||4 of abrake gear |.|5. ||6 is a tension spring drawing the brake lever H3 againsta stop ||1 mounted on the slide bar |04. I8 is an elastic strap, fastened with one end to a nose I I9 on dthe lower end of the slide bar |04 and fastenedV with the other end to lever |20, rotatably mounted on an axle concentric with the axis of rotation of the pointer 95. l guide-roller for the strap I8. Fastened to the lever |20 is a cam disc |2| adapted to be rotated with the lever |20. The lever |28 has a stop |22, adapted to bemoved against the locked pointer 95.

'I'he operation of this apparatus is as follows:

Pointer 95 is rotated by the circuit of the cell 90 in accordance to the density or transparency of the negative. As soon as the intensity of the cell-current has reached a predetermined degree, the push button |02 is released and the pointer is locked by the jaws 96 and 91. Then the slide-bar |04 is pushed down. Thereby the spring |05 is tensioned and the lever |20 with cam disc 2| is rotated by the strap ||8 until stop |22 contacts the pointer 95'. The slide bar may be moved further down on account of the elasticity The brake lever ||3 moves down in accordance with the lowering of slide bar |04 until it contacts the cam disc 'I2|. If slide bar |04 is vreleased from the pressure it moves upwardly under the action of the spring |05. On moving upwardly the nose- |06 closes by turning switch ||0` the circuit for the printing lamp and this lamp circuit is interrupted by the v nose |01. The speed of the upward-movement of slide bar |04 is decreased by the brake-lever ||3. The distance travelled after application of the brake i3 is adjusted by the position of cam disc |2l, which controls the `position of brake lever H3. The period between closing and interrupting of the circuit ||2 by switch ||0 corresponds to the distance travelled after application of the brake. In this manner the period of exposure is controlled by the cam disc I2| which in turn is controlled by lever 95' of moving-coilinstrument 94 and the cell-circuit. In order to adjust the period of exposure also in accordance to the sensitiveness of the printingr material the controlling elements f. i. cam |2|, lever 95, brake lever ||3 and nose |06 may be adjusted in advance. For the same purposes an adjustable resistance may be placed in the cell-circuit or an adjustable mask may be combined with the cell (see Figs. l and 2).

According to the embodiment shown in Fig. 9 the cam |2|' moved by the movinfz-coilinstru ment -94 is locked directly by jaws |24, opened by a Bowden-cable |00 and closed by a springr |0l In the embodiment shown in-Figs. l and 2 the transmission of the movement from cell arm 9 to lever 20, 22 is obtained by shaft extension |0' and bevel-gear Wheels |24 and |25. The gear wheel |25 has only teeth on a part of its circumference.

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described for obvious modilcations Letters Patent of the United States is:

1. In vcombination with'means for supporting a photographic negative/ in position to be exposed to light-rays, a photoelectric-cell movable above the negative and away therefrom, a moving-coil-instrument electrically connected to the photoelectric-cell, an adjustable resistance for the printing lamps and a controlling lever for this resistance movable by a spring and means for locking the controlling lever in different'positions which means are actuated by a circuit closed by the moving-coil-instrument.

2. In a photographic printing apparatus, the. combination of a source of light, means for sup-- porting a photographic negative in a position to be exposed to said source oi light, a photoelectric cell movable into a position in which it will be energized by light passing through a negative on said supporting means, a moving-coil instrument electrically connected with said photoelectric cell, an adjustable resistance for said source of light, a corgrolling lever for said resistance movable by a spring, and means for locking said controlling lever in different positions, said last named means being actuated by a circuit closed by said` moving-coil instrument.

3. In a photographic printing apparatus, the combination of a source of light, means for supporting a photographic negative in a position to be exposed to said source of light, a photoelectric cell movable into a position in which it will be energized by light passing through a negative on said supporting means, a moving-coil instrument electrically connected with said photoelectric cell, an adjustable resistance for said source of light, a controlling lever for said resistance movable by a spring, means for locking said controlling lever in diiierent positions, said last named means being actuated by a circuit closed by said moving-coil-instrument, and adjustable masking means between said source of light and said negative supporting means for varying the amount of light reaching the negative, said masking means being adjusted by said controlling lever at the same time the same varies said resistance.

4. In a photographic printing apparatus, the combination of a source of light, means for supporting a photographic negative in a position to be exposed to said source of light, a photoelectric cell movable into position to be energized by light passing through a negative on said supporting means, a moving-coil-instrument electrically connected with said photoelectric cell, an adjustable resistance for said source of light, a controlling lever for said resistance movable by a spring, means for locking said controlling lever in different positions, said last named means being actuated by a circuit closed by said movingcoil-instrument, an adjustable mask between said source of light and said negative supporting means for varying the light reaching the negative, said mask being adjusted by said controlling lever at. the same time the same varies said resistance, and an indicator mechanically connected with said controlling lever has been locked by said locking means the length of time the negative should be exposed when being printed.

5. In combination with means for supporting a photographic negative in position to be exposed to light-rays, a light-electric-cell movable above the negative and away therefrom, a moving-coil` instrument electrically connected to the lightelectric-cell, printing lamps below said supporting means, an adjustable resistance for said printing lamps, a controlling lever for said resistance movable by a spring, means for locking the controlling lever in different positions, said locking means being actuated by a circuit closed by the moving-coil-instrument, and a timeswitch-clock electrically connected with saidwhich it is energized by light passing through anegative on said supporting means, a movingcoil-instrument electrically connected with said photoelectric cell, an adjustable resistance for said source of light, a controlling lever for said resistance movable by a spring, means for locking said controlling lever in diilerent positions,

said last named means being actuated by a circuit clsed by said moving-coil-instrument, and a time-switch-clock electrically connected with said source of light for hunting the energization of the same to a predetermined length of time during the printing operation.

7. In a photographic printing apparatus, the combination oi a source of light, means for supporting a photographic negative in a position to be exposed to said source of light, a photoelectric cell movable into a position in which it will be energized by light passing through a negative on said supporting means, a moving-coilinstrument electrically connected with said photoelectric cell, an adjustable resistance for said source oi' light, a controlling lever for said resistance movable by a spring, means for locking said controlling lever in different positions, said last named means being actuated by a circuit closedA by said moving-coil-instrument, and an indicator mechanically connected with said controlling lever for indicating in the position in which said controlling lever has been locked by said locking means the length of time the negative should be exposed when being printed.

8. In a photographic printing apparatus, the combination oi a casing having two separate compartments, each of which being provided with a source of light and means for supporting a photographic negative in a position in which it is exposed to the source o! light therein, a photoelectric cell movable into a position in which it is energized by light passing through a negative placed on one of said supporting means, a-moving-coil-instrument electrically connected with said photoelectric cell, an adjustable resistance for the source of light which energizes the photoelectric cell through said negative, a controlling lever for said resistance movable by a spring, means for locking said controlling lever in different positions, said last named means being actuated by a circuit closed by said movingcoil-instrument, and an indicator mechanically connected with said controlling lever for indicating in the position in which said controlling lever has been locked by said locking means the length of time the negative should be exposed when placed for printing on said other supporting means.

9. In a photographic printing apparatus, the combination of a casing having two separate compartments, each of which being provided with a source of light and means for supporting a photographic negative in a position in which it is exposed to the source of light therein, a photoelectric cell movable into a position in which it is energized by light posing througha negative placed on one of said supporting means, a moving-coil-instrument electrically 'connected with said photoelectric cell, an adjustable resistance for: the source of light which energizes the photoelectric cell through said negative. a controlling lever for said resistance movable by a spring, means for locking said controlling lever in diiicrent positions, said last named means being actuated by a circuit closed by said moving-coilin strument, and a time-switch-clock for controlling the energization of the source of light which illuminates the negative when the. latter is placed for the printing operation on the other one oi said supporting means, said time-switch-clock including a rotatable shaft -on which said controlling lever is nxedly attached, and a pointer on said shalt for indicating in the position in which said controlling lever has beenlocked by said locking means the length of time the negative should be illuminated when placed for printing on said last supporting means.

` 10. In a photographic printing apparatus, the combination ot a source of light, means for supporting a photographic negative in a position to be exposed to said source o! Baht. a photoelectric cell position it is rotated by the current produced in said photoelectric cell, an electric circuit including said source of light and a switch, means controlling the opening and closing o! 'said switch, said means including a manually operable member adapted to be moved in engagement with said locked pointer, spring means for returning said manually operable member to initial position, spaced switch operating elements for closing and opening rpectively said switch during the return movement of said manually operable member, and braking means for controlling the length of the time period between the closing and opening of said switch by Asaid switch operating elements, said braking means being adjusted by said manually operable member' in accordance with the position the latter assumes when ensalina said locked pointer.

PAUL na.

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