US2351932A - Shutter - Google Patents

Description

June 20, 1944.

H. c. DECKEL ETAL SHUTTER 3 shetsa-sheet 1 Filed Jan. 8; 1941 Invehfors- Y CZOL M 621L071??- By Wan/z Jazz/er- W 1 "flair xflforn eys.

June 1944- H. c. DECKEL EIAL 2,351,932

- SHUTTER .Filed Jan. 8, 1941 f 3 Sheets- Sheet 2 Izna c2 lkiuarad Maura?" I By Zawr nvenfors June20, 1944. c. DECKEL E 2,351,932'

- SHUTTER Fil'ed Jan. 8, 1941 3 Sheets-Sheet 5 I mien fors G. 1m af M m ger BY 17-4702 fag/0r Mme?- imam Patented June 20, 1944 SHUTTER Hans C. Deekel, Munich-Solln, and Eduard Maurerand Franz Xaver Stiimmer, Munich, Germany; vested in the Alien Property Custodian Application January 8, 1941, Serial No. 373,640

In Germany January 8, 1940 t 11 Claims.

The present invention relates to a process for taking photographs.

With the photographic shutters heretofore known to the art the passage of light is controlled e. g. by swinging shutter-leaves, sliding curtains and the like; all these means, however,

require complicated actuating devices.

One object of the invention is to provide two polarizing filters relatively movable in relation to oneanother to control the passage of light when taking photographs. E. g. the actuation of a shutter" is facilitated thereby in the simplest manner.

Another object of the invention consists in the amount of the relative rotatory displacement of the polarizing filters in relation to one another being changeable at will.

A further object is that in the case of one stationary and one movable polarizing filter being used to control the passage of light, both filters may be rotated jointly into any desired position, and that the filter which is stationaryv during the exposure, can be fixed in the position named.

Finally further objects of the invention consist in one or both of the polarizing filters serving to control the passage of light being able to be formed square or as circular discs, rings or ring-sectors.

The form of filter most convenient for every individual case depends on the arrangement of same. Thus with a photographic camera one filter may e. g. be arranged stationary in the space in front of the sensitive layer and have a square form, whilst the second movable filter is arranged near the camera lens and has the form of a circular disc.

To these and other ends the invention resides in certain improvements and combinations of parts all as will be hereinafter more -fully described, the novel features being pointed out in the claims at the end of the specification.

In the drawings:

Figs. 1 to 4 are diagrammatic illustrations of diiferently formed polarizing-filters which in accordance with the present invention may be moved in diiferent ways in relation to one another to obtain the controlling effect of a photographic shutter.

Fig. 5 is a view showing a shutter constructed in accordance with the characteristics of the present invention, the individual parts of it being in position of rest;

Fig. 6 is a view similar to that of Fig. 5 with the individual parts in a position corresponding to the shutter under tension.

Fig. 7 is likewise a view similar to that of Fig. 5 with the individual parts in a position corresponding to the shutter when opened.

Fig. 8' is a view similar to that of Fig. 5 with the individual parts in the closed position subsequent to the openingof the shutter;

Fig. 9 is a partial view similar to that of Fig. 5, constructed in accordance with the present invention with an exposure regulating mechanism arranged additionally.

Fig. 10 is a view illustrating a shutter constructed in accordance with the characteristics of the present invention and with which the amount of the relative movement of the polarizing-filters in relation to one another is changeable at will and in which furthermore the parts are in position of rest.

Fig. 11 is an end elevation with parts of such a shutter being shown in vertical-section.

Fig. 12 is a. view similar to that of Fig. 10 with the individual parts in a position corresponding to the shutter under tension.

Fig. 13 is a view similar to that of Fig. 10 with the individual parts in a position corresponding to the position of the shutter when running down.

Fig. 14 is a view similar to that of Fig. 13, but with an exposure value adjusted difierently.

Fig. 15 is a view representing a shutter constructed in accordance with the characteristics of the present invention and with which the shut ter as a whole is rotatably adjustable about the optical axis of the photographic camera, and in which furthermore the parts are in position of rest.

Fig. 16 is a partial view-similar to that of Fig. 15, in which individual parts occupy a differential position.

Fig. 17 is a partial view in direction of the arrow inserted in Fig. 15 with the individual parts on a large scale; and

Fig. 18 is a view similar to that of Fig. 15 with the individual parts in a position corresponding to the position of the shutter when open.

It is a physical phenomenon known in itself that the path of rays of light may be controlled by means of two polarizing-filters changeable in their reciprocal angular adjustment; this control is possible due to the fact that the electromagnetic waves of the light which are polarized after having passed through the first filter, that is to say which can no longer swing but in one definite plane, cannot pass through a second filter unless its individual structural parts are parallel or approximately parallel to the structural parts of the first filter. If, however, the structural parts performs B of the two filters lie at a corresponding angle e. g. at right angle to one another, any passage of the light polarized in the first filter through the second filter is impossible. According to the present invention this possibility of control resulting from the wave-like nature of the light was the base ior the construction of a photographic shutter.

In Figures 1 to 4 several arrangements of polarizing filters acting as shutters are shown the individual filters or which may be moved in diflerent ways to admit or to impede the passage of rays of light respectively. I

With the arrangement according to Fig, 1, two polarizing filters I and 3 are arranged in such a manner in a photographic camera not shown that their axes of rotation I and I coincide with the optical axis or the apparatus. with this arrangement a control of light in the sense or the invention may be achieved e. g. by making the one filter (l) stationary, while the other filter (I) is rotatably adjusted forward and backward in relation to the former (I) in its plane about the axis 5 by 90; instead of this the filter I might also be rotatably adjusted in the same direction twice by 90 in relation to the other filter and only subsequently returned to its original position. This return-movement may e. g. again be executed in two rotations by 90 each in relation to the stationary filter (this resulting at the same time in a new working step of the shutter) or filter 3 which is immovable during the precedins step is rotatably adjusted by 180 jointly with filter I, the shutter thus remaining closed durin the return-movement (closed winding up). Naturally, the return-movement may be effected iorwards or backwards; hence results as a special case a shutter in which the movable filter (I) continuous rotation by 90 each.

Instead of one movable and one stationary polarizing filter also both filters I and I can be movable and be rotated simultaneously against one another about the axes I and I to control the passage of light, the possibilities of movement being the same as indicated above, and the only difference consisting in the angles of rotation being half as large.

A further possibility oi performing the movements of the filters to control the passage of light is given with the arrangement according to Fig. 1, by e. g. filter I being rotatably adjusted by 90 in relation to the stationary filter 8 and thereupon filter a hurrying 'aiter filter I which is now at rest,'by the same degree of angle. For the return-movement the same possibilities indicated I above exist also in this case.

Finally it would also be possible to rotatabLy adjust both the filters alternately by 90 each in relation to each other (thus in directions remaining constant).

In Fig. 2 an arrangement of filters is shown with which a filter II can swing about an axis II lying outside the optical axis 9 and at right angle to the latter. The second filter u is supported stationary in the photographic camera. with this arrangement the passage or light is controlled by filter I I being swung out of the path of rays to allow the .light to pass through; to

interrupt the passage of light filter II is thereupon swung back again to its original position shown in Fig. 2. Naturally also filter I4 might be supported swingable by a second axis lying parallel to axis II. the opening and closing or the passage or light beins the two filters I I and Il Jointly. Besides it would a,ss1,ess

also be possible to swing one or both the filters about axes cutting the optical axis 9; in this case one filter or both of them might be swung by 90 each to control the passage of light.

' the camera lens IS. The arrangement might also be made in such a way that but one of the two filters is constructed swingable whilst the other filter lies stationary in front of the camera lens I9; the area of the stationary filter may then be limited to the aperture of the camera lens.

With polarizing filters having their axes of rotation outside the optic axis of the camera the same relative movements are possible to control the passage of light in itself as enumerated in connection withthe example of execution according to Fig. l, the only difierence consisting in the filters illustrated e. g. in Fig. 1 are always executing merely pure rotations as self-motions. whilst with the arrangements according to Figs.

2-4 a swinging of the filters takes place. These swinging self-motions of the filter or filters respectively render it possible that the free passage of light may also be effected in such a way that one filter or both (contrary to the rotating filters which cover each other in every position) are partially or entirely removed from the path of rays. When releasing the passage of light by removal of one filter or of both of them, the distance of the axes of rotation of the filters from the optical axis may be chosen at will. thus also infinitely large; in the latter case the swinging motions of the filter or filters would become parallel displacements.

The polarizing filters shown in Figs. 1 to 4 may be arranged singly or jointly immediately at-the camera lens or/and between the lens and the light sensitive surface.

In Figs. 5 to 9 an example of execution of a photographic shutter according to the invention is shown where the axes of the two polarizin filters drawn for reasons of greater clearness with different diameters coincide with the optical axis of the photographic camera.

The shutter consists of two disc-like polarizing filters 20 and 22 which are supported rotatably about their joint middle axis 24 at a corresponding distance and covering one another in a photographic camera not shown. The filters carry stops 20 and. 28 which are engaged when the shutter is in the position of rest (Fig. 5) by pawls 30 and 32 supported rotatably at the places 34 and 38; by these pawls the filters 20 and 22 are safeguarded against displacement in their position of rest in which no light can reach the emulsion-carrier due to the reciprocal angleelected by swingin position of the structures of their material. Furthermore a master member 38 having the same axis as the two filters and carrying a setting lever 40 is supported rotatably. Said setting lever adjoins in theposition shown in Fig. 5 with its one side formed accordingly two stops 42 and it provided at the circumference of filters 20 and 22 respectively. The ends oi two tension springs 45 and 48 as well as of a retracting spring 50 are also fastened to the setting lever 40. The springs 40 and as are anchored with their other ends in the filters 20 and 22 at 52 and 54, whilst the secexpansion of springs 46, 48 and 60 adjusted by rotation by an angle of 90 in a clockwise direction into the position shown inFig. 6 and it is held there in position by a pawl 60 activated by a spring; during this motion 01' tension the filters 20 and 22 are held by the pawls 30 and 32 in their original position impeding the passage of light. When the release lever 62 arranged at the pawl-lever 30 is pressed down against the action of its spring 64, the pawl 30 is lifted thereby out from the notch 26; thuspfilter 20 is released and vthe force of the tensioned spring 46 displaces same rotatably towards the right, until. stop 42 comes again to adjoin the setting lever 40 (Fig. 7). Corresponding to the path of tension of lever 40 the angle of displacement by rotation of the filter amounts to 90 in doing so. By this rotatory displacement of the one filter against the other one which is still held in its position by pawl 32, the passage of light to the emulsion carrier is released so that the shutter is open in the position shown in Fig. 7. Shortly before filter 20 completes its opening movement, the stop 26 provided on it reaches an arm 66 of pawl 32 and imparts both of them a short rotation to the left against the action of a spring 60; thus stop 28 is released and now the second filter moved by the force of spring 48 hurries after the first filter, until stop 44 comes to adjoin lever 40 which likewise corresponds to an angle of rotation of 90". Thus both the springs 46 and 48 are released, and the reciprocal position of the filters being the same now as in Fig. 5, the shutter is closed again (Fig.8).

So as to bring the entire set back again to the position of rest shown in Fig. 5 automatically and without opening the shutter, the filter disc 22 carries a stop 10. When ending the closing movement, this stop encounters an arm I2 of pawl 60 and displaces both against the force of spring 58 in such a way that pawl 60 i lifted out from its notch at the setting lever 40. Thus the force of the retracting spring 50 comes into effect and turns the setting lever 40 or the master member 38 respectively and with same over the stops 42 and 44 also the two polarizing filters jointly towards the left, until the notches 26 and 28 have passed under the evading pawls 30- and 32, and are back again in the position shown in Fig. 5. Any rotation of the filters'towards the left beyond these positions of rest is prevented by stop I4.

In Fig. 9 the shutter described above is shown with an exposure regulating mechanism of known kind arranged additionally for executing exposures of difierent durations. This exposureregulating mechanism 80 is supported in a suitable manner in the shutter casing and is impelled by a lever 82 protruding into the path of an arm 84; this arm forms part of the mu'ltiple-arm-lever I2, 86 supported in the point of rotation 36. This device is acting in the following manner:

After actuating the release lever 62 the filter- 20 is displaced by rotation by force of spring in a clockwise direction in the manner already described. The stop 26 moved with it by this action encounters shortly before ending this rotatory movement the arm 66 and attempts to rotate the latter and the levers connected with it about point 26. This rotatory displacement, however, is delayed by the exposure regulating mechanism 80, so that the release of the stop 28 by pawl 32 and thus the beginning of the closing movement of the second filter begins only after. a certain time. The amount of this delay determining the duration of exposure may be determined at will in known manner by corresponding adjustment of the exposure regulating mechanism. The return oi the exposure regulating mechanism to the position of rest determined by a stop 86 is effected by a tension spring 88.

It may still be mentioned that it is, of course, possible without difllculty to intercalate between the release lever 62 and the pawl 30 a retarding device of known construction. 7

Building in an exposure regulating mechanism in a shutter naturally involves the shutter being made more complicated and more expensive. So as 'to avoid these drawbacks a shutter may be used as shown in Figs. 10 to 14 of the drawings. With the shutter shown in these figures exposures may be effected which had so far only been possible by producing different speeds of running down, without interfering with the speed of running down of its moved parts, that is to say without using adjustable exposure regulating mechanisms or the like. This effect is produced by taking advantage of the wellknown physical fact, that the amount of the light allowed to pass through is dependent on the mutual position of two polarizing filters at the time.

According to Fig. 10 two disc-shaped polarizing filters 90 and 92 are arranged at a corresponding axial distance and covering one another in a photographic camera not shown, their common middle axis 94 coinciding with the optical axis of the photographic camera. Furthermore the arrangement of the two filters is suclrthat filter 90 may berotated about axis 94, whilst the filter 92 is supported not rotatably in the photographic i camera. For the purpose of its displacement by rotation the filter 90 is held in a ring-shaped mounting 96 which shows at its circumference two adjoined pieces 98 and I00. Adjoined piece I00 is engaged by a tension spring I02 and tends to rotate mounting 96 and consequently filter 80 in a clockwise direction, until adjoined piece I00 comes to adjoin a stop I04 (Fig. 10). In a position shown in Fig. 11 a rotatable master mem.- ber I06 is arranged which is provided with a han dle I08 and has the same axis as the two filters.

This handle is engaged by a tension spring IIO which is stronger than spring I02 and tries to displace by rotation the master member I06 in an anticlockwise direction until the handle I08 comes to lie against a stop II2. At the one side of the member I06 a two-arm pawl is supported rotatably at II6. As shown in Fig. 10, this pawl lays itself under action of a spring II8 with a hook-shaped end I20 against the circumference of the mounting 96. The other arm of the pawl shows an oblique surface I22. Finally another adjoined piece I24 is at the circumference-of member I06 behind which piece, when the s utter is tensioned, the hook-shaped end of a release pawl I26 subject to the action 01 a spring I28 falls.

As shown in Fig. 11 another rotating ring I20 is arranged between the two filters 90, 92 and having the same axis as they, this rotating ring carrying a projection I32 .and near it a stop I33. Projection I32 engages on turning the ring (by means of a handle I34) notches I36 provided'at a scale I38 at the individual graduation lines of same. The graduation lines of this scale designate exposure corresponding to the usual durations of exposure (e. g. /2 3 6 of a second etc.) obtained by the known shutters. In the graduation of the scale not only the function according to which the passage of light is taking place dependent on the relative motion of the filters, but also other factors influencing the action of the shutter (e. g. lack of uniformity in the movements of the filter OII etc.) are considered.

The action of the shutter described is as follows:

In position rest of the shutter (Fig. the position 0! filter it is determined by the lengthening piece Illl adjoining stop I. In this posi tion the particles of structure of filter 90 are at right angles to the particles of structure of the stationary filter 02 so that the passage of light through the shutter is blocked. When the'shutter is put in tension member I06 is moved by means of handle I" against the force of spring IIII away from stop I I2 in a clockwise direction, until stop I comes to lie behind the hook of release pawl I, the master member thus being held firmly in its new position (Fig. 12). On reaching the position of tension the hook-shaped end I oi the two-arm pawl moved together with member Ill catches besides under the action of spring III behind the adjoined piece 98 of filter-mounting N. The position of filter 90 in relation to filter 02 has not been altered during the action of tension, so that the shutter has preserved its closed position. When the release pawl III is now moved in the direction or the arrow against the force oil-spring III, the adioined piece I is released and member III is displaced rotatably in an anticlockwise direction by the shutter 'spring III. During this rotatory displacement the rotatably supported filter II is carried along by means 0! pawl III and adioinedpiece 9! under tensioning oi spring III .(the latter being weaker than spring III). This rotatory displacement of filter 00 together with member I" lasts, until the oblique surface In of the pawl supported at Ill buttsagainst stop I" protruding'into its path and glides along it. During this action the pawl is displaced by rotation against the force of its spring Hi, and thus stop 98 or the filter-mountmg I is released (Fig. 13) Whilst master member Ill continues now its path until handle I",

adjoins stop I I2. filter II is retracted to its original position shown in Figs. 10 and 12 in a clockwise direction by the spring I02 coming now into action.

as becomes apparent from the above, the position of stop I" in every case is determining the amount 0! the rotary displacement of filter 9!. As on the other hand with polarizing filters the amount of light allowed to pass through depends according to a wellknown physical law in'every case on the amount of the reciprocal relative movement of two filters, it is possible by adjustment of stop I by means of the handle Ill to alter at will the amount of light reaching the carrier of emulsion when the shutter is running down. though the speed 0! running down or the shutter always remains the same. with the example of execution described the notches i" of scale Itl'are amused in such a manner that during the rotatory displacement or filter II adiusted thereby the same amount of light is allowed to pass through as'with the usual durations of exposure of the known sector-shutters; these durations 0! exposure are therefore indicated at the respective notches. although the process of opening 0! the new shutter difiers on principle from that of. the known shutters.

'In I'lga. 10, 12 and 13 the shutter or the stop Ill or same respectively is adlustede. g. to'an amoimtotlightcorrespondinltothatatan member I to such an extent (when the shutter runs down) that'its particles of structure are lying at the end of the opening movement at an acute angle to the particles or structure of the stationary filter 82 (see Fig. 13).

Contrary to it Fig.-"'1'4"shows the adjustment of stop I33 to the largest amount at light which in the present case is to correspond e. g. to that at I a period of exposure of 5 see. As may be seen from the figure, in this instance filter SU-is separated from member Ilii only at the end of the rotatory adjustment of the latter; with thisoper ation the rotatory displacement of the ifilter is so large that in relation to the structural particles of filter 92 its own structural parts come,

to lie in parallel position in which, as is known. the highest degree of penetrability is reached,

In the manner described all values of exposure obtained heretofore by adjustment of the period of exposure may be attained with a shutter according to the present invention without any alteration of the speed of the shutter-partsinoved being necessary. The device forming the obiect oi the invention may therefore be cons'tructed in a simple manner without any means altering the speed (such e. g. adjustable exposure regulating mechanisms) with but one speed of running down.

With an additional arrangement on the means generally known in the construction oi shutters for carrying out,B- 'and T-exposures and conse quently not shown indetail it is possible without difilculty with a shutter according to the invention to execute also such exposures.-

Finally it maybe mentioned that a reduction of-the'. path of rotation of master member I06 and of the movement of the filter by half might be achieved by the filter 92 which with the example of execution described is not rotata-' ble, being likewise arranged rotatable and being controlled by suitable means in such a way that it moves by the same amount as filter ill, but in opposite direction when said filter is rotatably adjusted.

The quality of a photograph may under certain conditions'strongly be interfered with by the light of reflection occurring on smooth surfaces.

In Figs. 15 to 18 a shutter bearing the features oi the present invention is shown which besides the control of the passage of light may also be used for subduing or eliminating to the greatest possible extent the disturbing light of refiection mentioned. As is well known, due to the physical fact that reflected light is polarized for its greater part, that is that it only continues to swing in one definite plane, it is possible to subdue reflected light in general by means of a polarizing filter; therefore. all that is necessary is to rotatably displace a polarizing filter intercalated in the path of this light, until its structural particles lie vertical to the direction of swinging of the light whereby the latter is practically extinguished.

when. using a shutter with winch polarizing filters are serving to control the light, in the usual photographic cameras with a finder or in cameras with a special finder chamber it is pos= sible'to subdue and eliminate reflected light in a simple manner. All that is necessary in. such cases to support the shutter on a rotating disc at the photographic camera, in order to be able to displace it by rotation as a whole; it has to 15 be rotatably adjusted in every case by the same amount as a polarizing filter intercalated before the finder or the finder-lens respectively has to be rotatably, displaced in order that its structural particles get into the position vertical to the swinging plane of the reflected light and thus extinguish same. By the shutters being rotatably displaced at the same time its one filter which is not moved during the process of exposure, gets be obtained e. g. by reading and new adjustment of the respective amount of displacement by rotation at corresponding scales, or also by the filter arranged in front of the finder being coupled with the shutter (e. g. over gear-wheels) so that same is in every case moved along with it by the same amount at the movements of adjustment of the filter.

In consideration of the particularly simple circumstances described above, .showing an example of execution of a shutter for the kinds of photographic cameras mentioned above has been dispensed with; as an example a shutter has been chosen that is suitable for being used with photographic cameras with ground glass plate adjustment or with refiex cameras with joint photographic and finder lens, and with which consequently special means have to be provided for so as to be able to open the shutter during the adjustment of thecamera. Such a shutter is de-- scribed hereafter under reference to the drawings.

According to Fig. 15 two disc-shaped polarizing filters I42 and I44 are arranged at corresponding axial distance and covering each other in'a shutter-casing I40, their joint middle axis I46 coinciding with the optical axis of the photographic camera. Furthermore the arrangement of both filters is such that filter I42 may be rotated in relation to thecasing I 40 about the axis I46, whilst filter I44 is arranged non-rotatable in casing I40. For the purpose of its rotatory displacement filter I42 is held in a ringshaped mounting I48 having two adjoined pieces I50 and I52 at its circumference. Adjoined piece I52 is engaged by a'tension spring I54 tending to rotatingly displace mounting I48 and ter I42 in a clockwise direction until stop I52 comes to butt against astop I56 forming part of a rotating ring I51. having the same axis as the two filters; this ring carries a handle I58 and by means of same it may be rotatingly displaced between two stops I59 and I60.

' Furthermore a master member I6I having the same axis as the two filters I42 and I44 is rotatably supported in casing I40 and carrying a handle I62. This handle is engaged by a tension spring I64 of greater force than that of spring I54 and tends to displace rotatingly member I 6| in an anticlockwise direction, until handle I62 adjoins a stop I66 provided in casing I40. At the one side of member I6I a two-arm pawl is rotatably supported at I68. This pawl is formed as a hook I at its one end and shows an oblique surface I12 at its other end. Besides a spring I14 tries to rotatingly displace the pawl in a clockwise direction, which is impeded in the positions shown in Figs. and 18 by a stop pin I16 arranged in casing I 40. At the circumference of member I6I an adjolned piece I18 is providedbehind which the hook-shaped end of a release pawl I80 places itself, when the shutter is under tension, this pawl I 80 being subject to the action of a spring I82. The release pawl may be actuated either immediately by means of a hand lever I84 or over a wire release I86 from any desired place of the photographic camera not represented in de tail.

In casing I40 a hand lever I90 is rotatably supported by an axle I88 which is subject to the action of a tension spring I 92. A plate spring I94 fastened at the end of leve'r I90 influences a pawl I96 likewise rotatably supported by axle I88 in such a manner that it lays itself with its stop I98 against the one side of lever I90. The hookshaped end of pawl I96 protrudes in certain positions into the path of the lengthening piece I52 of filter mounting I48. g

The hand lever I90 penetrates through the shutter casing I40 in a hook-shaped recess I99 limited on one side of the cover plate 200 of the shutter (Fig. 17).

. position of rest shown in Fig. 16 into the acting position shown in Fig. 15 or 18 handle I90 is rotatingly displaced about axle I80 from its end position a shown in Fig. 1'1 against the action of spring I92, until it drops into a notch 202 by its i own tension and is held there firmly (position c).

During this process pawl I96 is carried along by plate spring I94. For the return movement of lever I90 from this position said lever must be 202; only then I pushed out by hand from notch spring I92 can enter into action.

Apart from the immediate operation .by hand as described the rotary displacement of lever I90 from its position a may also be effected by a flexible cable thrust device 204 from any desired place of the photographic camera. The end of this fiexible cable thrust device when actuated presses against a correspondingly formed spot of lever I90 and moves same again towards notch 202. The path of the end of the flexible cable thrust device is so limited, however, that lever I 90 can-' .not drop into notch 202, but only gets as faras position b in which pawl I96 is already in position of action in relation to the adjoined piece I52. From Fig. 17 it may be seen without difilculty that lever I90 is not blocked in position b so that it returns to its final position a under the pull of spring of disengagement, when'the action of cable thrust device 204 has ceased.

The cases of immediate actuation of lever I90 the flexible by hand-or by using the thrust device 204 will be explained in detail later on.

The individual parts of the shutter described above are arranged in casing I40, and according tothe invention this casing is rotatably supported about the axis I46 at a photographic camera not represented in detail. To displace casing I40 (and with it the shutter as a whole) by rotation a handle 206 is provided. Furthermore casing I 40 carries on a part of its circumference providing about an arch-shaped plate 200 the border of which is provided with teeth 2I0. The teeth are engaged by a stationary supported spring 2I2 securing the shutter casing in its angular position at the time against unintended rotatory displacements. On plate 208 an angle-graduation 2I4 (suitably agreeing with the individual teeth 2l0) is provided so as to be able to fix the individual amounts of rotatory displacement also numerically.

Before describing the process of-eliminating To move pawl I96 from its- I92 without any special movement,

reflected light by the means according to the present invention, we will first explain the action of the means serving to execute the exposure proper.

In position of rest of the shutter (Fig. 15) the position of filter I42 is determined by the lengthening piece I52 adjoining stop I00. In this position the structural particles of fiber I42 are at right angle to the structural particles of filter I44 supported incapable of being r-otatingly displaced in casing I40 so that the passage of light through the shutter is blocked. When the shutter is put in tension, member ISI is moved against the force of spring I04 away from stop I in a clockwise direction, until adjoined piece I comes to lie behind the hook of the release pawl I00 and the master member is thus firmly held in its new position. Besides, on reaching the position of tension, the hook-shaped end I10 of the two-arm pawl supported by member ISI drops under action of spring I14 behind the adioined piece I00 0! filter mounting I48. The position of filter I42 in relation to filter I44 has not been altered during the process of tension, so that the shutter preserved its closed position.

when the release pawl I00 is now moved against the force of spring I02 either by means of hand lever I04 or over the wire release I80 in a clockwise direction, stop I10 is released and member III is rotatingly displaced by spring I04 in an anticlockwise direction. By this rotatory displacement the rotatably supported filter I42 is carried along over pawl I10 and adioined piece I00, whilst spring I04 is tensioned (it being weaker than spring I04) This rotatory displacement of filter I42 together with member IOI lasts, until the oblique surface I12 of the pawl supported at I00 butts against stop I10 protruding into its path and glides along it. In doing so, the pawl is displaced rotatingly against the force of its spring I14 and stop I00 of filter mounting I40 is released thereby. At this moment the position of filter I42 is such that its structural particles lie parallel to those of filter I44, so that the passage of light to the emulsion carrier is released. Whilst now master member IOI comes to rest by lever I02 butting against stop I00, filter I42 is brought back to its original position shown in Fig. 15 by its spring I04 and thus the passage of light through the shutter is blocked again. Whilst the exposure is executed, hand lever I90 is in the position shown in Fig. 1 6 in which pawl I00 lies outside the .path of lengthening piece I02, so that itcannot enter into action.

It may still be mentioned that means for regulating the speed of shutter (exposure regulating mechanism) has for reason of simplicity been omitted in the example of execution shown.

If'now, before carrying out an exposure, a refiected light emanating from a shining surface or the object of which a photograph is to be taken, is to be eliminated, this may be done e. g. with a photographic camera with ground glass plate adjustment in the following manner:

After insertion of the ground glass plate into the photographic camera the lever I00 is first rotatingly displaced to its notch-position 0 shown in Fig. 10 and particularly in Fi n rin I01 is moved by means of handle 00 from its position shown in Fig. 10 into the position shown in Fig. 18 as far as stop I00. By this operation also filter I42 is carried along over stop I00 and lengthening piece I02 against tho-force of spring I04. Shortly before the movement of ring. I01 ends, lengthening piece I02 drops behind the pawl I96 protruding now into its path, so that filter I42 is held fast in its new position. In this position, however, its structural particles lie parallel to those of filter I44 fastened in casing I40, so that the sight through the shutter is unobstructed (Fig. 18). This opening of the shutter by means of handle I58 may be carried out independently from the master member IBI being in position of rest or of tension.

Whilst looking through the ground glass plate inserted into the photographic camera, the shut ter as a whole should be rotated by means of the handle 200 about axis I40, until the structural particles of filter- I44 lie vertical to the swinging direction of the polarized reflected light, this being practically extinguished thereby. The adiusted angular position is secured by spring 2I2 engaging teeth 2I0. Then the adjustment is finished, lever I00 is again displaced rotatingly into its position a, pawl I00 being removed from the path of the lengthening piece I02 over stop I98. Filter I42 now moves under action of spring I04 and carries long ring I01 back into the position shown in Fig. 15, the passage of light through the shutter being blocked again. After exchanging the ground glass plate with the exposure material the exposure may now be executed in the manner previously described with the adjusted angular position or the shutter.

Fixing filter I42 in the open position shown in Fig. 18 may also be eifected by operating the flexible cable thrust device 204. During this op eration, however, the lever I is, as described previously, displaced rotatingly only as far as position b, so that when the pressure brought to bear on it ceases, it returns again to its original position a under action of spring I02 and removes pawl I00 from the path of lengthening piece I02. Thus filter I42 is in this case held in Open position only during the operation of the flexible cable thrust device 204.

The movement of pawl I00 over the device 204 is particularly suitable for photographic cameras with a joint photographic and finder lens because with these apparatuses a certain erroravoiding constraint in the sequence of the various actions is rendered possible thereby. This sequence is e. g. as follows:

If, in taking a photograph, disturbing reflected light is to be eliminated filter I42 must be rotatingly displaced into the open position by means of handle I00. In this position the filter is held fast readily by pawl I00, because with the last named kind of photographic cameras it is convenient to arrange the flexible cable thrust device 204 in such a way that it continuously tries under spring pressure to hold lever I00 in position b and thus pawl I00 in acting position. Now the open shutter can be rotatingly displaced by means of handle 200 into the corresponding angular position in order to eliminate the reflected light. Before or after this adjusting movement the shutter must be put in tension in the usual manner by means of handle I02.

After finishing the adjustment 8. release member provided at the photographic camera is actuated. This results first of all in the device 204 being pulled back from its acting position into the position of rest, and consequently in lever I00 being brought back by spring I02 from its position 0 into the original position; in doing so, filter I42 is released by pawl I00 for the shutting movement. By further actuating the release member the swingable mirror (arranged in reflex c m ras with but one lens) after closing the the camera lens and lastly pawl I is actuated over wire release I86, and thus the'process of exposure is brought into effect.

From using 'the flexible cable thrust device I86 and 204 to operate members I80 and I00 respectively results finally with photographic cameras of any construction the advantage that the operation places may be. arranged at will at the photographic camera, and (due to the flexibility of the thrust devices) preserve their original position when the shutter is rotatingly displaced.

For reasons of operation it may be advantageous with a shutter according to the invention to make the opening and closing movements of the polarizing filters corresponding to a chosen variation with regard to time to execute an exposure. This may be achieved without difllculty by using means known in the art (e. g. by inter- 'calating controlling curves) Whatwe claim is:

1. A photographic shutter for use with a camera, said shutter comprising a pair of shutter members formed of polarizing material, the shutter members being aligned with each other and being normally held in a position wherein their axes of polarization are crossed, means for mounting. said shutter members whereby they may be moved relative to each other from said normal position to a position wherein their axes of polarization are parallel, and movable actuating means connected to said shutter members for carrying out a shutter operating cycle wherein the shutter members are adjusted from said normal position to a position in which their axes are parallel and are then returned to said normal position.

2 A photographic shutter carried by a camera, said shutter comprisin a pair of spaced apart and aligned shutter members which are mounted for rotation about a common axis, said shutter members being formed of polarizing material and being normally positioned with respect to each other to have their axes of polarization crossed, and movable actuating means connected to said shutter members for carrying out a shutter operating cycle wherein one of said shutter members is rotated from its normal position through 90 after which the other shutter member is rotated from its normal position and in a, similar direction through 90 following which both shutter members are simultaneously returned to their" normal position.

3. A photographic shutter mechanism carried by a camera, said shutter mechanism comprising a pair of spaced apart and aligned shutter members which are mounted for rotation about a common axis, said shutter members being formed of polarizing material and being normally positioned with respect to each other to have their axes of polarization crossed, movable actuating means connected to said shutter members for carrying out a shutter operating cycle wherein one 01' said shutter members is rotated from its normal position through 90 after which the second shutter member is rotated from its normal position and in a similar direction through 90 following which both shutter members are simultaneously returned to their normal position and adjustable control means associated with said shutter mechanism and actuated by said operating means for determinin the instant when the operating means initiates the rotation of the second shutter member from its normal position.

4. A photographic shutter carried by a camera,

said shutter comprising a pair of spaced apart and aligned shutter members which are mounted for rotation about a common axis, said shutter members being formed of polarizing material and being normally positioned with respect to each other to have their axes oi'polarization crossed,

an operating member releasably engaged with said shutter members, said operating member being rotatable on said axis of rotation, resilient means secured to the operating member and to the shutter members and to a fixed member carried by said camera; said operating member being rotatable in one direction against the action of said spring means, releasable means for securing said operating member in a working position where it has been rotated against the actionof said resilient means, means carried by one of said shutter members when released from engagement with said operating member and rotated for releasing the second shutter member from engagement therewith, and means carried by said second shutter member when released from engagement with the operating member and rotated for releasing the operating member from its working position.

5. A camera shutter comprising a pair of spaced apart and aligned shutter members both of which are formed of polarizing material and one ofwhich is rotatable about an axis common to both of said shutter members, the shutter members being normally positioned with respect to each other to have their axes of polarization crossed a and movable actuating means connected to said shutter members for carrying out a shutter operating cycle wherein the rotatable shutter member is rotated from its normal position to a position wherein its polarizing axis is oriented with respect to the polarizing axis of the fixed shutter member so that light incident to one shutter member will pass through both shutter members after which the rotatable shutter member is returned to its normal position.

6. A camera shutter mechanism comprising a pair of spaced apart and aligned shutter members both of which are formed of polarizing material and one of which is rotatable about an axis common to both of said shutter members, the shutter members being normally positioned with respect to each other to have their axes of polarization crossed, movable actuating means connected to said shutter members for carrying out a shutter operating cycle wherein the rotatable shutter member is rotated from its normal position to a position wherein its polarizing axis is oriented with respect to the polarizing axis of the fixed shutter member so that light incident to one shutter member will pass through both shutter members after which the rotatable shutter member is returned to its normal position, and adjustable means carried by said shutter mechanism for predeterminedly varying the'degree of rotation imparted to the rotatable shutter member by said actuating means whereby to vary the time period 8. A camera shutter comprising a pair of spaced apart and aligned shutter members both of which are formed of polarizing material and one or which is rotatable about an axis common to both of said shutter members, the shutter members being normally positioned with respect to each other to have their axes of polarization crossed, resilient means urging the rotatable shutter member into said normal position, a rotatable ring member positioned between said shutter members and axially aligned therewith, other resilient means urging said ring member to an inoperative position whereby said ring member when rotated to a position for operating the shutter is returned to its inoperative position on its release from its operating position, and means for coupling said ring member to said rotatable shutter member when th ring member is moved to its operating position and for maintaining said coupling until the ring; member has returned to its inoperative position whereby said rotatable shutter member is moved from its normal position on the return of the ring member to its inoperative position, the resilient means associated with said rotatable shutter member returning such shutter member to its initial crossed relation with respect to the second shutter member on the release or said coupling means.

9. A camera shutter as set forth in claim 8 including movably adjustable means for contacting and releasing said coupling means on the return of the ring member to its inoperative position, the position of said adjustable means determining the degree of rotation 01 the rotatable shutter member during its coupled connection with the ring member, and relative fixedly positioned means engageable with said adjustable means for retaining the adjustable means in desired position.

10. A camera shutter mechanism comprising an open-ended casing rotatably adjustable about an axis passing through the ends thereof, a pair of spaced apart shutter members within the easing aligned on the axis of rotation of said casing and rotatable with the casing, one of said shutter members being rotatable about the casing axis and the other being relatively fixed with respect to said casing, both oi! said shutter members being formed of polarizing material and being normally positioned with respect to each other to have their axes of polarization crossed, movable actuating means connected to said shutter members for carrying out a shutter operating cycle wherein the shutter member which is rotatable relative to said casing is rotated from its normal position to a position wherein its polarizing axis is oriented with respect to the polarizing axis of the other shutter member so that light incident to the relatively rotatable shutter member will pass through both shutter members after which the relatively rotatable shutter member is returned to its normal position, and means for retaining said casing in adjusted position.

11. A camera shutter mechanism as claimed in claim 10 having rotatable actuating means for rotating said relatively rotatable shutter member to a position where light is passed through both shutter members, said rotatable actuating means rotating the relatively rotatable shutter member from its normal position independentlyot the actuating means for carrying out a shutter operating cycle and the last-named actuating means returning the relatively rotatable shutter member to its normal position from the position into which it has been independently rotated.

HANS C. DECKEL. EDUARD MAURER.

FRANZ xavan s'rommna.

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