US1715526A - Photographic enlarging and reducing apparatus - Google Patents

Description

June 4, 1929.' s. WILLIAMSON PHOTOGRAPHIC ENLARGING AND'REDUCING APPARATUS I Filed Aug. 6, 1927 2 Sheets-Sheet ,Invent (/M/ www June 4, 1929.

S. WILLIAMSON PHOTOGRPHIC ENLARGI'NG AND REDUCING APPARATUS Filed Aug. 6, 1927 2 Sheets-Sheet 2 @MS-Iggy A any.

een@ June 4.11929;

STATES f 1,715,526 PATENT OFFICE.

STUART WILLIAMSON, OE LONDON, ENGLAND, ASSIGNOB F ONE-HALF T0 COLIN MARTIN WILLIAMSONLOF LONDON, ENGLAND.

PHOTQGIRAPHICl ENLABGING AND RELUCING APPARATUS.

Application led August 6, 1927, Serial No. 211,187, and in Great Britain Aug-ust 28, 1928.

Photographic enlarging or reducing apparatus consists essentially of three elements, a negative carrier, a support for the sensitized paper or the like and a lens between them.

This invention relates to such a paratus of the kind wherein the adjustment of one element in relation to a second automatically adjusts the third through a transmission which includes a cam of suitable contour so that the projected image is always kept in focus.

For any distance apart of the negative carrier and paper support greater t-han the minimum (at which the projected image is equal in size to the object i. e. the negative) there are two possible positions of the lens. In one the lens will be nearer the negative and an enlarged image will be formed, in the other it will be nearer the paper and a reduced image will be formed, the ratio of enlargement in the one case being equal to the ratio of reduction in the other. It is obvious. therefore that a given over-all length of apparatus will allow of the same range of enlargement and reduction if suitable adjusting mechanism can be provided. A single cam mechanism for both enlarging and redueing over a large range suffers as a general rule from certain mechanical difficulties due to the variation in relative speed of the moving elements.

The object of the present invention is to vprovide automatic focussing mechanism of the type first herein set forth in which the whole enlarging and reducing range for the maximumlength is available, in which this whole range is traversed without interruption or reconnection of parts preferably by means of a single manually operated gear and 40 which satisfies the mechanical requirement that the rapidly moving element shall be manually operated" and the cam gear shall operate the slower moving element.

According to this invention the negative carrier-and the paper support are each provided with a cam, while the lens support carries a cam follower which engages one cam for one part of the range and the other cam for the other partof the range. The moving carriages can be adjusted by hand if desired,

but preferably operating gear with a single manually controlled handle is provided which during the appropriate part of the range moves the rapidly moving element.

The change over from one cam to the other conveniently takes place at the 1:1 position and a bell crank lever pivoted to the lens carrier has a cam follower, such as a roller, on each arm, one vfor each cam. For the enlarging range of adjustment, when both the lens and negative carrier move away from i the paper support, the lens is manually adjusted, and the cam attached to the paper support 1s operative. The` follower for the cam on the negative carrier bears on a plain part of tlns cam which thus acts as a link to move the negative carrier. For the reducing range, when the lens moves towards the paper support and the negative carrier away from the paper support, the negative carrier is manually adjustedand the cam thereon is operative, while the follower on the other cam bears on a plain portion thereon.

v The manually operated mechanism conveniently consists of a pair ofcords or chains. each provided with a stop, which are moved 1n opposite directions by a single handle. One stop is arranged tocontact with a member connected to the lens support when this 'is to be directly adjusted, and the other stop 30 to contact with a member connected to the negative carrier when that member is to be directly adjusted. The cord or chain may if desired be endless, and pass over pulleys or sprockets one of which is adapted to berotated by hand. Instead rack and pinion or any other convenient mechanism such as a lever train may be used. It will be understood that in the arrangement just described the paper carrier is on the stationary part vof the apparatus. If desired the negative carrier vmayv be stationary when the above description -would still apply if the terms enlarging and reducing are interchanged'. 95

The .cams may comprise slots in suitable members to ensure the followers being positively operated. Preferably, however, they are single surfaces or edges against which the followers are pressed, in order to avoid back-lash due to wear and clearance. Springs may be used for this purpose, or where the apparatus `is vertical, the weight of the parts may be arranged to provide the necessary pressure.

The accompanying drawings illustrate by way of example a vertical -enlarger embodying the invention.

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and a lens bracket 8 is provided with front Aform standards 4a, 4b.

Figure 1 is a side view in section, and Y Figure 2 is a front View, of the complete apparatus in the 1: 1 position.

Figure 3 is a section on lthe line I-I of Figure 4 with the parts in position for the maximum ratio of enlargement.

Figure 4 is a horizontal section through the base,and .l

Figure 5 is a horizontal section taken between the moving carriages. i

The framework of the apparatus 1s formed by a base 1, a pair of front legs 2 and a pair of tubulairear legs 3 extended upwards to On the base 1 is carried a suitable paper support 5 of anybconvenient kind. A lens carriage comprising a pair of side members `6 joined by cross bars 7 rollers 9 and rear rollers 10 engaging the standards 4 so that the carriage can run up and down. This carriage and its associated parts are partly counter-balanced by a weight 32 within the standard 4b, connected by a cham 33 running over suitable pulleys. A negative carriage comprising side members 11 joined by cross bars 12 carrying rollers 13 also runs on the standards, above the lens carlriage.v This carriage carries a negative holder 14 of suitable construction and a lamp house 15 which can be supplied with a current of air from a blower 16 in order to keep it cool. This carriage and its associated parts are partly counter-balanced by'a weight 30 ruiming in the standard 4". A bellows 17 joins the negative carriage to the'lens carriage.

` A fixed cam 18 is secured to the base 1 by a bolt 19 and a moving cam 2O is secured to the negative carriage by a bolt 21. Abell crank lever 22 is pivoted at 23 to a bracket 24 on the lens carriage and` bears rollers 25, 26, at each lend4 respectively engaging the cams 18, 20, the

weight of the parts maintaining contact. The respective operative edges of these cams are made up, of plain parts 18a, 20a, androntoured parts 18", 20h. In the 1:1 position shown inFigures 1 and 2 the rollers 25, 26, are at the junctions of the plain and contoured parts of the cam edges. The cams are respectively prevented from turning laterally about their securing bolts by vrollersy 27, 28 on the bracket 24running againstthe straight sides of the cams. In the case of the cam 18 its weight prevents it from swinging away from the roller 27. In the case of the lcam 20, where its weight tends to swing' it `away from the roller 28, a tension spring 29 securedbetween the negative carriage and the cam maintains contact.

Starting withthe 1: 1 position if the negative carriage be raised the lens carriage will descend at a slower speed under the control of the plain cam portion 18, the contoured cam portion 20h, and the bell crank lever 22. If the lens carriage be raised, the negative carriage will rise at a slower speed under the control of the plain cam portion 20a, the contouredcam portion 18b and the bell crank lever 22. In each case if one carriage is directly A moved the other moves more slowly under cam control so that the forces involved are small and friction has alow value and in consequence both in design and action the aphandle enabling it to be taken right through the range from the eXtreme position of maximum enlargement to the extreme position of maximum reduction, the application of the direct force being automatically changed from one carriage to the other at the 1: l position, there are provided a winding gear and chains adapted to co-act with the counter- Weights 30 and 32. The counter-weights respectively carry pulleys 34, 35, over which pass chains 36, 37. These chains at one end carry weights 38, 39 and at their other ends are wound on a drum 40 in such direction that when one is wound on the other is wound off at substantially the 'same rate'.- The drum 40 is rotated from a handle 42 through a worm gear 43. 'I his renders iine adjustment easyu `and being irreversible ensures the parts remaining as adj usted. For greater security the worm spindle can be locked when adjusted ing head 45. The weights 38, 39 are adapted to form stops when they contact with the counter-weights 30, 32 and the lengths o f'the chains 36, 37, are such that in the 1 1 position by a screwclamp 44 having a milled operatthey are just taut with the weights 38 and 39 in contact with the counter-weights.v If now the handle is turned to pay out the chain 36 and wind up the chain 37, the counter-weight 32 will be drawn down and the lens carriage -directly lifted. The cam gear will cause the negative carriage to rise and the counterweight 30 and weight 38 will run downwards.

The parts will finally reach the position of' extreme enlargement shown in Figure 3.- If

the rotation of the handle is'now reversed, the parts will return to the 1:1 position of Fig'- ures 1 and 2'and from here without interruption the counter-weights 30 will be drawn down and the negative carriage lifted directly. The lens carriage will automatically descend under the conrtol of the cams until the extreme reduction position is reached with the negative carriage in the same position as `tor eXtreme enlargement. The descent of the lens carriage causes the counterweight 32 to rise, but since the speed of descent is slower than the speed at which weight 32 so that the weight 39 la the negative carria e rises, the chain 37 is paid out more rapidly t an the rise of the counterand there is no interference with t e-proper action of the parts. Obviously the apparatus can be run straight from any one adjustment v 1the other cam for the other part of the range,

said cams being separately in action.

2. In automatic focussing photographic enlarging and reducing apparatus, a negative sup ort, a sensitive surface support, a cam fixed on each of said supports, a lens support, a cam follower on said lens support engaging one cam for one part of the range andthe other cam for the ot er part of the range, said cams being separately in action and operating gear Wih a single manually operated handle for au omatically actuating directly Y the more rapidly moving supporti 3. In automatic focussingl photographic enlarging and reducing a paratus, a negative support, a sensitive sur ace support, a cam fixed on each of said supports, a lens su port, and a bell crank' lever pivoted to said lens support with its ends co-acting respectivelfy with said cams which act separately at di ferent parts of the range.

4. In automatic focussing photographic enlarging and reducing apparatus, a fixed support, a travelling support, a travellin lens carriage intermediate said supports, a ocussing cam covering the enlarging range, a second focussing cam fixed on the other of said supports covering the reducing ran e, a plain portion on each of said cams and a ell crank lever pivoted on said lens carriage having each arm co-actin with one of said cams, one arm co-acting wit the plain part of the enlarging cam when the other arm co-acts with the active part of the reducing cam, and vice versa.

5. In automatic focussing photogra hic enlarging and reducing apparatus', a Xed support, a travelling lens carriage, a travelling support, a cam fixed on said fixed support, a cam fixed on said travelling support, a cam follower on said lens carriage, a single manually controlled handle, means for connecting said manually controlled handle with said lens carriage when said lens carriage and said travelling support are both moving 1n the same direction, and means for connecting said handle with said travelling support behind when they are both moving the opposite rections.,

6. In automatic focussing photogra hic enlarging and4 reducing apparatus, a xed support, a travelling lens carria e, a travelling support, al'cam'on lsaid fixe support, a

-cam on said travelling support, a cam follower on said lens carriage, a one way flexible .coupling `connected to said lens carriage, a

one wa flexible coupling acting in the opposite irection to said first fiexible coupling, connected to said travelling' support, and manually operated means for actuating both vsaid flexible couplings in opposite directions simultaneously.v

7. In vertical automatic focussingphotographic enlarging and reducing apparatus, a fixed support, a travelling lens carriage, a first weight partly counter-balancing said lens carriage, a travelling support above said lens carriage, a second weight partly counter-balancing said travelling sup ort, a cam on said xed support, a cam on sai travelling support, coupled cam followers on said lens carriage co-acting respectively in turn with said cams, an operating handle, a drum rotated by said operating handle, a pair of flexible members wound on said drum, and a stop on each flexible member co-acting respectively in turn with said weights.

8; In automatic focussing photogra hic enlarging and reducing apparatus, a xed support, a lens carriage, a travelling support, a ocussing cam on one of. said su portscovering the enlarging range, a secon focussing camon the other of said su orts covering the reducing range, a cam fdlihwer for each cam, on said lens carriage, a single manually operated'handle, and means for coupling said handle to feed said lens carriage and travelling support in turn.

9. In automatic focussing photogra hic enlarging and reducing apparatus, a xed support, a lens carriage, a travelling sup ort, a cam held stationary by a pivot on said y xed support and a lateral stop on said lenscarrlage.

10. In automatic focussing photogra hic enlarging and reducing apparatus, a ed support, a lens carriage, a travelling support, a cam held stationary with res ect' to said travelling support b a pivot t ereon and a lateral stop onsaid ens carriage.

11. In automatic focussing photographic enlarging and reducing apparatus, a fixed support, a lens carriage, a travelling support, a cam secured in stationary relation to said fixed support, a second cam secured in stationary relation to said travelling support, each of said cams being held by a pivot on its respective support and a lateral stop on said lens carriage.

12. In vertical automatic focussing photographic enlargingand reducing apparatus,

a fixed support, a lens carriage, a travelling support, an edge cam on said xed support,l

5 on each'end of said bell crank lever each coacting with one of said cams, one roller being on the lplain part of one camwhen the other roller is on theactive partof vthe other cam. 13. ln vertical automatic focussing photographic enlarging and reducing apparatus, a `fixed support, a lens carriage, a travelling support, an edge cam on said fixed support, lan edge cam on said travelling support, a plain portion on each of said cams, a bell crank lever on said lens carriage, a roller on each end of said bell crank lever each co-acting with one of said cams, one roller being on theplain part of one cam when the other roller is on the active part of the other cam 0 and manually operated irreversible means for directly operating said lenscarriage, when said lens carriage and travelling support are moving 1n the same dlrect-lon and for directly operating sai-d travelling sup-l 0 port when sald lens carriage and travellmg support are moving in opposite directions.

, 14. In vertical automatic focussing photographic enlarging and reducing apparatus, a fixed support, a lens carriage, a travelling support, an edge cam secured at one point on said fixed support, an edge cam secured at one -point on said travelling support, rollers on `said lens carriage locating said cams laterally, a -plain portion on eachv of said cams, abell crank lever on said lens carriage, and a roller on each end of said bell crank lever each co-acting with one of said cams, one roller being on the plain part of one cam when the other roller is on the active part of the other cam. i

15.Y .In vertical automatic focussing photographic enlarging and reducing apparatus, a

fixed support, a lens carnage, a travelllng Support, an edge cam on said fixed support,` an edge cam on said travelling support, a plain portion on each of said cams, and a bell crank lever on Laid lens carriage having each end coacting with one of said cams, one end co-aetmg with the plain part of one cam when the other end is co-acting with the active part ofthe other cam.

In testimony whereof I. have signed my name to this s eciicat-ion.

TUART WILLIAMSON.

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