A DEVICE FOR CYCLICALLY REARRANGING A STACK OF SHEETS

Abstract: A device for cyclically rearranging a stack of sheets, in particular photographic prints. Such prints tend to adhere to one another, and the invention provides sheet edge engaging elements for preventing malfunctions as double removal or uncontrolled displacements of such prints.

Description: A DEVICE FOR CYCLICALLY REARRANGING A STACK OF SHEETS The present invention relates to a device for cyclically rearranging a stack of substantially rectangular sheets. In particular, such sheets may be photographic prints of nominally identical size. Such devices will therefore briefly be designated "photo changers". Prior art photo changers have been disclosed by the published PCT appli¬ cations WO 86/03028, WO 88/03280, and WO 89/04991. The known photo changers, and the photo changer of the present inven¬ tion, too, comprise several common features: A first frame member forms a housing and a second frame member forms a drawer received in the housing and reciprocable between an inner end po¬ sition and an outer end position. A stack of prints is held by the drawer so that a first pair of opposite print edges is substantially parallel to the direction of the drawer reciprocation while the other pair of oppo¬ site print edges is substantially orthogonal to this direction. Upon withdrawal of the drawer, removing means in the housing engage an indivi¬ dual print so as to retain it in the housing while the remaining prints of the stack are carried along by the drawer which is provided with hol¬ ding means so as to push these prints across the retained individual print. When the drawer is pushed home from its outer end position towards its inner end position the individual sheet or print removed at one stack end is displaced towards the other stack end and added again to the stack. In this manner, a new print appears beneath a display window of the housing upon each drawer reciprocation. The present invention deals with events occurring during the first phase of the reciprocation, i.e. the drawer withdrawal. In use of the prior art photo changers sometimes, and unpredictably, malfunctions occurred in that not only the one print at the stack end was removed but also a second print adjacent thereto. It is the object of the present invention to provide photo changers in which malfunctions of this type are substantially suppressed. In order to overcome the drawbacks of the prior art, the invention provides first protection means for preventing such a second print from operative interengagement with the removing means and second protec¬ tion means for preventing such a second print from being passed across, together with the to-be-removed individual print, by the stack remainder holding means. In order to better understand the invention it may be helpful to dis¬ cuss at first the design and operation of the photo changers of the prior art mentioned above. The photo changer in accordance with WO 86/03028 comprises a support for the to-be-removed print surface adjacent that transverse edge there¬ of which is first passed by the separator bar which serves as the holding means for the stack remainder. The support is preceded by a step having a height commensurate with the thickness of the prints such that the trans¬ verse edge of the to-be-removed print is located behind and protected by the step so that it cannot be engaged by the separator bar while the transverse edges of the remaining prints are exposed and presented to the separator bar to be carried along by the latter. However, adjacent prints may strongly adhere to one another due to humidity or electrostatic charges. Therefore, the print to be removed and some of the remaining prints adjacent to it are braked by means of resiliently arranged oblique surfaces engaging the transverse edges opposite those which are engaged by the separator bar. The braking force may be sufficient to retain the individual print which is to be removed in the housing while all other prints, pushed by the separator bar, slip across the braking surfaces. The photo changer of WO 88/03280 is of similar design. However, the gap through which the to-be-removed print must pass and which is defined between the support and the separator bar is shaped such that this individual print becomes corrugated and thereby stiffened in direction of the drawer withdrawal. Where the oblique surfaces cannot brake the print anymore a hook or the like may be provided which engages over the respective transverse edge of the print and pull it in front of a stop. The photo changer of WO 89/04991 is provided with hooks which extend substantially orthogonal to the print plane so as to positively engage the print edge. These hooks replace the braking oblique surfaces of the earlier designs. The photo changer of the present invention also is pro¬ vided with such hooks while the system separator bar - step - support has been retained. The malfunction discussed above may be due to two reasons. The distance between the step and the removing means (oblique surface or hooks) is, of course, adapted to the print size. When the drawer is in its inner end position, however, the inner transverse edges of the prints are located in front of the step. Upon withdrawal of the drawer, at first the entire stack is shifted through several millimeters until the inner transverse edge of the to-be-removed print has passed the step and is pressed towards the support behind the step. As the prints have some clearance in drawer reciprocation direction they are not aligned either with their transverse edges. A second print which extends beyond the first (i.e. the to-be-removed) print may get caught with its transverse edge in the removing means for the first print. This may happen even in case all prints of the stack are of exactly identical size which, unfor¬ tunately, is not always true; dimensional tolerances within several mil¬ limeters are quite frequent. The device must be able to handle prints of maximum size within a given range. Under these circumstances it may hap¬ pen that a print which is "too short" is caught by the removing means when its other transverse edge has passed the step long ago, and a second "normal" print may be bent with its other transverse edge into the free space between the step and the other transverse edge of the "short" print which should be removed. Thus, the transverse edge of the second print is hidden behind the step, and the separator bar overruns it so that the first plus the second print are removed simultaneously. The problems in connection with prints of different size are discussed in WO 86/03028 mentioned above. It was assumed that a second oblique sur¬ face following the first one could still catch an "oversize" print once it has passed the first oblique surface already. Such a system may handle the prints properly only if it is indeed the print to be removed which is correctly placed behind the step which, as discussed above, is not necessarily so. Moreover, as the to-be-removed print is only braked but not positively held there is a risk that no print at all is retained in the housing if first and second print strongly adhere to one another. WO 89/04991 also suggests a solution. The hook which serves as the re¬ moving means is preceded by a ramp. A "short" print which is to be re¬ moved is pushed beneath a "long" print caught by the hook so as to throw the long print out of engagement with the hook. This system, however, can cope with tolerances of 0.5 millimeters only. The probability of malfunctions which the present invention is inten¬ ded to overcome is the higher the more the prints are curved about an axis extending orthogonally relative to the drawer reciprocation direc¬ tion and particularly if the center of curvature is beneath the display window. The preceding explanation will have clarified the principle of the present invention. The prior art ignored the problem of initial mis¬ alignment of the prints and thus tried to deal with only one of the two reasons of malfunction. Further, the "wrong" print was allowed to get in engagement with the removing means and had to be disengaged again. In contrast thereto, the means of the present invention prevent such initial contact of the second, third... print which permits to allow a broader print size tolerance range. Embodiments of the present invention are illustrated in the accompany¬ ing drawings and will be explained in detail with reference to the drawings hereunder. As the removing means for the individual print or sheet are hook shaped in all embodiments they will be termed "hook" for sake of simplicity. Further it is to be noted that only those details are illustrated which are of importance for the present invention, i.e. those which are effective during the withdrawal of the drawer; details which are effective during the second phase of the drawer reciprocation may be derived from the publications mentioned above, the disclosure of them being incorporated by reference. Finally, it will be understood that the drawings are not to scale but frequently enlarged because otherwise, the thickness of a photographic print of 0.2 to 0.25 millimeters could not be illustrated. Fig. 1 and 2 illustrate schematically the function of a first embodi¬ ment in two positions, Fig. 3 shows in elevation the lever which is only indicated in Fig. 1 and 2, Fig. 4 shows in elevation a second embodiment, Fig. 5 is a plan view of the embodiment of Fig. 4, Fig. 6 illustrates in plan view a detail of this embodiment, Fig. 7 is a partial section view of a further detail, Fig. 8-10 show three phases of operation of a further embodiment, Fig. 11 shows a modification of this embodiment, Fig. 12a shows in elevation view a rail with a photo stack, Fig. 12b shows a search member allocated thereto, Fig. 12c is a plan view of the search member, Fig. 13 is an enlarged detail view of Fig. 12b, Fig. 14 and 15 serve to explain the embodiment shown in Fig. 16 and 17, Fig. 18-21 illustrate four phases of the function of a further embodi¬ ment, Fig. 22 is a plan view to the embodiment of Fig. 18-21, Fig. 23 shows a modification of the preceding embodiment, Fig. 24 is a section view in the area of the steps, Fig. 25 and 26 are partial section views to illustrate the sheet sepa¬ ration in the vicinity of the steps, Fig. 27 and 28 illustrate two functional phases of a further embodi¬ ment, Fig. 29 is a section view along line 29-29 of Fig. 30, Fig. 30 is a plan view of the hook assembly of Fig. 27-29 and also defines the section plane of Fig. 27 and 28, Fig. 31 is a front view of the hook assembly including a portion of the separator bar, Fig. 32-34 show respectively an elevation view, front view, and plan view of the hook element, Fig. 35 and 36 illustrate the function with differently curved photo prints, Fig. 37 illustrates the function of the hook in a certain instant of the drawer withdrawal motion, Fig. 38 is a section view of the hook bearing seen orthogonally with respect to the bearing axis, Fig. 39 shows how a separated sheet comes clear of the hook, Fig. 40 is a section view of the drawer seen from the front unto the separator bar, Fig. 41 shows important details of drawer and housing in plan view, Fig. 42-44 illustrate the function of the individual elements shown in Fig. 40 and 41, Fig. 45 illustrates in isometric view a modification of the rocker of the embodiment shown in Fig. 27-38, Fig. 46 is a broken away plan view of the modified rocker mounted in the rail , Fig. 47 and 48 show the cooperation of rocker and separator bar in the last embodiment upon drawer reciprocation. The invention is illustrated under the assumption that the principal design of the photo changer as disclosed in WO 89/04991 is used, i.e. that the stack of prints is supported on resiliently biased rails. It is to be understood, however, that the invention is applicable to other changer designs as well. The top profile of the rails is designated with 500. This rail profile includes a main surface 502 on which, with the drawer in its inner end position, the entire stack including the print to be separated is suppor¬ ted. With the start of the drawer motion the stack is conveyed from right to left in the drawings so that the print directly supported by the rail and to be separated from the stack may be caught by the hook 504 while the remaining prints of the stack pass across the hook; it will be under¬ stood that for this reason the hook must not be higher than the thickness of one print. A step or ramp 506 precedes the hook, and one leg of a V-shaped lever 508 extends into the area immediately in front of the step while the lever is pivotably journalled adjacent its apex; in the present embodi¬ ment, the bearing is provided on the rail. It may be assumed for the purpose of this description that a "short" print is to be separated and that the second print in the stack is "long". When the entire stack is displaced along the rail the leading edge of the second print (which is not to be separated) abuts lever arm 510 and pivots the lever in counterclockwise direction, the other lever arm 512 being pivoted in the same sense and through the same angle until the lever has reached a position indicated in broken lines in Fig. 1. The second lever arm 512 engages thereby beneath the "short" print which is to be separated and which, in turn, is lifted and lifts the "long" print over and beyond hook 504. With further displacement of the stack the second lever arm 512, too, is pivoted beneath the rail profile so that the print to be separated is caught by hook 504.- With the drawer in its outer end position the lever is returned into its initial position by means of e.g. a bias spring system.- The angular distance of the two lever arms defines the differential length to be compensated and which depends upon the stiffness of the prints having maximum curvature. Similar considerations apply to all embodiments which will be explained in greater detail hereinafter. Fig. 4 through 7 show again the rail 514 with its profile 500. A rocker 518 is mounted in the rail pivotably about a pin 516. Initially, the position of the rocker is defined by a stop 520 engaged by a counter stop 522 on the rocker under the action of leaf spring 524. Fig. 4 also illustrates the critical case where a short print is superposed by a long print from which the short one is to be separated. In Fig. 4 the long print 526 has just pivoted the rocker out of its rest position because the print has hit head 528 of the rocker. Leaf spring 524 has been de¬ flected by the tail portion 530 of the rocker. Adjacent the free end of spring 524 there is an auxiliary hook 532 to be engaged by the leading transverse edge of print 534 which is to be separated once the remaining clearance 536 is passed. Spring 524 is not rigidly mounted on rail 514 but its free end 538 is disposed in a guide portion of the rail so that the spring is displaceable in direction of the outwards movement of the drawer. During this displacement, auxiliary hook 532 also overruns head 528 of the rocker and is taken along by the print to be separated until it hits the main hook 540 and plays the role of the latter. Before this event, however, a second spring arm 542 integrally formed with spring 524 has lifted the second print 526 to an extent to permit it to pass across the main hook because the free end of this spring arm which is angled at 544 had passed across a control ramp 546 and had been deflected upwards, i.e. away from the rail. When the auxiliary hook approaches the main hook the second spring arm slips off the ramp so that the print 534 to be separated reaches a position in front of the hook. A spring element (not shown) returns the spring into its initial position when the drawer has reached its outer end position. Such a spring element may be formed e.g. by coiling the guided end 538 so to form a tension spring. In Fig. 5 the dimension "D" is indicated which designates the maximum length difference in direction of drawer motion. This dimension is the distance between the rest position of the auxiliary hook and the main hook. The minimum length difference which is allowable without the second print bending into the main hook in front of the first print is about 0.5 millimeter and is realized by the distance separating the rest position of the auxiliary hook from the rocker head where the latter is engaged by the second print. Fig. 8 through 11 show schematically another design approach. Again, 514 designates the rail and 500 its profile. A search element 600 is slidably mounted in the rail and biased by tension spring 602 into a position in which it abuts a stop 604. The search element has a sensor arm 606 extending beyond rail profile 500 into the expected path of a print.- The drawings illustrate again the critical situation. The long print 526 is the second and superposes short print 534 which is to be separated. Long print 526 has hit sensor arm 606 and has displaced it together with the entire search element to the left in Fig. 8 through 10 against the bias of spring 602. A control slider 602 which is guided on the rail so that it can be displaced upwards has a wedge surface 610 cooperating with a similar wedge surface 608 of the search element. In result, displacement of the search element to the left causes an upward displacement of the control slider which adjacent its upper free end has a ramp. With the control slider being raised hook 504 is bridged. Print 526 slides along ramp 614 and thereby comes clear of sensor arm 606 which is returned towards its initial position. If a further print follows, the search element cannot entirely return because the sensor arm hits that further print, namely the transverse edge of print 534; the latch arm 616 of the search element blocks the control slider which continues to bridge the hook. When print 534 is lifted from the sensor arm by hitting ramp 614 there is no print any more to stop the search element which, accor¬ dingly, returns to its initial position and releases the control slide; that permits the hook 504 to catch the transverse edge of print 534. Control slider 612 is guided along ribs 618 and is spring-biased into its initial position. Fig. 11 shows a modification of this design. Search element 600 is integrally molded with control slider 612 and connected thereto by means of a so-called film hinge 620. It will be noted that the two alternatives act in similar fashion. Fig. 12a through 13 show schematically a further design. It is based on the approach that both the leading and the trailing transverse edge of the print which is to be separated are sensed from the bottom side. For this purpose, two sensor sliders 700 are mounted to be displaced along the rail independent of one another. Each sensor slider has at its distal end at least one hook. One of the hooks is the removing hook 504 while the other one forms the protecting step 702 behind which the transverse edge of the print is hidden when the separator bar pushes the stack thereacross. Initially, however, the two sensor sliders assume an inwards position shown in side view in Fig. 12a and 12b while Fig. 12c is a plan view. This initial position is chosen so that the distance between the two hooks 702 and 504 is shorter than the shortest admissible print 534 minus a safety margin to cope for any misalignment of such a shortest print. Thus, both hooks will initially be within the exposed surface of the lowermost print to be separated.- Fig. 12c indicates a bowed leaf spring 704 which connects the inner ends of the sensor sliders. Spring 704 extends into the path of a cam or the like on the drawer (not shown) which upon start of the drawer withdrawal exerts a force in direction of arrow 706 so that the sensor sliders move away from one another. Fig. 13 shows in an enlarged view one of the sensor sliders adjacent its end portion. Once it has been displaced in direction of arrow 708 until its step 702 (or hook 504 for the other sensor slider) is aligned with the respective transverse edge of the print 534 to be separated step 702 is brought in engagement with that edge because the stack above print 534 is spring loaded. Means are provided to latch step 702 and hook 504, respec¬ tively, in just this engagement position. For example, a leaf spring 710 is depressed by print 534 and anchors itself in a toothed rack 712 or simply in a piece of foamed plastic. The same event occurs at the other end of print 534 so that the latter is "framed" regardless of its position relative to the rail. The holding means (separator bar) may now convey the remaining prints of the stack across the separated print 534 irrespective of the relative dimensions of the second print. When the drawer has reached its outer end position, print 534 is lifted from "frame" 504/702 so that the leaf spring 710 is unloaded and the sensor sliders may return into their initial positions. Fig. 14 through 17 show a further embodiment. Fig. 14 and 15 illustrate why a relatively rigid straight rail having a hook 504 either does not catch a print at all (Fig. 14) or catches the transverse edge of a wrong print (Fig. 15) depending upon whether the prints are curved out¬ wards or inwards. According to Fig. 16 and 17 hook 504 is provided on a very flexible leaf spring 720 which extends with its tail 722 along the rail and adapts itself to the contour of curved prints while the contour 500 of the rail is angled downwards. This allows adaptation of the leaf spring 720 to prints of inverse curvature, cf. Fig. 17. An auxiliary extension 724 of the spring is supported on the rail top side so as to stabilize the resilient portion of the leaf spring.- Most photographic prints are curved over their entire length but always in the same sense i.e. they never assume an S-profile. Therefore it is sufficient that the hook-carrying spring senses the "overall" curvature in order to avoid a malfunction due to print curvature; the fact that the last few milli¬ meters of the spring 720 are initially not in engagement with the print does not affect its function. A further embodiment is shown in Fig. 18 through 22. Fig. 18, 19, 20 and 21 illustrate successive phases of a separation sequence with prints of different size in "critical" order of prints. These drawings show the end of a rail 514, and a stack 800 of prints is shifted along the top profile of the rail. A pinion 802 lies loosely in the rail end in front of hook 504 seen in direction of the displacement of stack 800. Pinion 802 is supported by an end 804 of a rollpath 806 and by a leaf spring 808 which is biased to abut stop 810 on the rail laterally offset with respect to the pinion so as to define a waiting position of the pinion. The following description of the operation will reveal that the pinion can perform its function even if it is not held in the waiting position by gravity, depending upon the position in which the user holds the changer.- According to Fig. 19, at first the transverse edge of the long second print 526 hits the teeth of pinion extending just beyond profile 500 of the rail. This causes the pinion to be pivoted about the end edge 804 until it is in contact with the rollpath 806. When in this situation the transverse edge of the following print 534 hits the pinion the latter is rotated, the rollpath serving as a "bearing", whereby the preceding print 526 is lifted across removing hook 504. As illustrated, there is no print which could follow print 534. As soon as print 534 has reached, in engagement with the pinion, a position in which the pinion is subjected to a force directed towards the rail profile the pinion is pushed back into its initial position (even without the help of gravity since the stack transmits a force in the desired direction). If a further print would follow print 534 the sequence of events as described above is re¬ peated, and it is an advantage of this embodiment that it functions pro¬ perly even if the first print is short, the second is of medium size, and a third long one actuates the pinion first. Fig. 21 illustrates the situation in the vicinity of the outer drawer end position. The separator - - bar whose shoe 813 passes along the separated print 534 between a pair of pinions (cf. Fig. 22) in that a roller 812 presses the print unto a strip 811 made of retentive material is short of the pinions which must "dive" in order to avoid an inadmissible deformation of the print. This diving is possible since the spring 808 yields and brings the pinions back once the separated print is lifted from the rail. It will be seen in the drawings that each pinion carries short hubs 814 which, however, do not have a bearing function; instead, they engage behind resilient ribs which are deflected upon assembly and then serve as stops to prevent the pini¬ ons from falling off the rails. Fig. 23 shows a modification based on the same principle. The pinion is replaced with a toothed segment 816 encircled by a spring 818. Portion 820 of the segment abuts a stop projection 822 of the rail which also serves as a stop for the spring which biases the segment into this ini¬ tial position with the free spring end 824. The segment is journalled by means of its hubs 826 and returns into its initial waiting position be¬ cause of the spring bias when the drawer is fully withdrawn. The broken line contour of the segment shows that it is actuated by prints of quite different lengths. Rotation of the segment beyond the indicated position is continued until all prints have passed the segment. A control wire 828 may be displaced along the rail so as to engage the segment and to clamp it about in the position shown in broken lines. If then the drawer is withdrawn it will convey all prints out of the housing so that another stack may replace the previous one. The wire is manually actuable but will be returned automatically into its inactive position upon the drawer being pushed fully home. The embodiments described so far except that of Fig. 12a through 13 related to means for solving the problems in the area of the removing means i.e. the hook which engaged the trailing transverse edge of the to-be-removed print and where a malfuction may occur even in case of the prints being of equal size. Hereinafter, means are described for elimina¬ ting the reasons for double separations in the area of the step-and- support system, referring to Fig. 24 through 26. The step-and-support systems 900 are disposed in pairs on ribs. A control wing 902 is disposed laterally with respect to an allocated rib and has a top surface which is substantially in alignment with a guide path 904 in front of the step. Shoe 906 which is supported in the separa- tor bar under spring bias rides first on path 904 upon start of the drawer withdrawal. The control wing blocks initially any access to the support faces, and no print edge may hide behind the protective step. Only when an opposite transverse print edge has been caught by hook 504 the removing force exerted on the respective print raises steeply, and because of the inclination of the shoe the control wing 902 will be de¬ flected against its spring bias. The leading transverse edge of the tobe- removed print may now be placed on the support while the shoe carries along the remaining prints of the stack. In Fig. 24 the control wing 902 is carried by a spring 908 made of plastic while in Fig. 25 and 26 leaf springs 912 bias wings pivotable about 910 against stop members (not shown). Referring to Fig. 27 through 44, the preferred embodiment of the pre¬ sent invention will be described. Fig. 27, 28 and 29 are section views of the end of a rail 1000 which, in reduced scale, is shown in plan view in Fig. 30. In Fig. 30 the section lines for the preceding Fig. is also in¬ dicated in Fig. 30. The rail is molded from cheap plastic material e.g. polystyrene and has a bearing pin 1002 the section shape of which is shown in more detail in Fig. 38. A rocker 1004 is snapped unto pin 1002 from the left rail end in Fig. 27 and thereafter pivoted into the position illustrated in Fig. 27/28; during this pivoting motion a nose-shaped stop integrally molded with the rail can yield. This stop 1006 limits any pivoting movement of the rocker in clockwise direction as shown in Fig. 28; the rocker 1004 has a counter stop 1008. The rocker has a hook 1010 integrally molded therewith. The hook is larger than than a slot-shaped recess 1012 of the rail which houses the rocker; in this manner, the pivoting of the rocker is limited in counterclockwise direction. The rocker is molded from a plastic material which is substantially more abrasion resistant than polystyrene, e.g. polyacrylic resin since otherwise, the hook would be ground away by the rough rear face of the prints which slip thereacross. The enlargement of the hook reduces the surface pressure acting on the edge of the to-be-removed print. It will be noted that the hook 1010 is undercut thereby tending to anchor at a print although the height of the hook is in the order of the print thickness. Thus, when the drawer is fully withdrawn the print can¬ not be released from the hook by a simple lifting operation; instead, the print transverse edge must be withdrawn from the hook in a direction about parallel to the rail. This will be explained in detail hereunder. Each rail is provided with two hooks 1010 in symmetrical disposition relative to and bilaterally of a retentive strip 1014. A print to be se¬ parated is pressed against this retentive strip by a roller 1020 housed in a shoe 1018 which, in turn, is resiliently supported by separator bar 1016. The path of the retentive strip is raised in the vicinity of the rocker so that the prints may be conveyed across this uppermost site of the rail. This may be seen in Fig. 29 and 31. The contour of the rocker where it is exposed at its top side is shaped such at the bearing eye 1022 for bearing pin 1002 a plane sensor surface 1024 is provided from where the contour slopes off to either side. Bearing pin 1002 is shaped and disposed such that the joint defined by the pin is as close as possible to the sensor surface 1024 but its top end must not extend beyond this plane, cf. Fig. 38. Fig. 35 and 36 illustrate the operation of the hook system. The stack of prints at first engages the oblique ramp portion 1026 and then reaches the plane area 1024 which adapts itself to the bottom side of the adja¬ cent print. The rocker is pivoted thereby depending upon the sensed cur¬ vature (in most cases, the print is not really plane). The position and the height of the catch hook are desigend such that it will be passed or overrun by all prints 1030 as long as a shorter print (one which "ar¬ rives later") is in contact with surface area 1024. The maximum differen¬ tial length is defined by the distance spacing the catch hook and the end edge of the plane sensor surface 1024 adjacent to it. Fig. 37 shows how the transverse edge of the separated print is re¬ tained when the rail is depressed by the separator bar overrunning the rail. Fig. 39 shows in longitudinal section elements of the changer in their position shortly before the complete withdrawal of drawer 1040. The se¬ parator bar 1060 still presses the separated print 1032 unto rail 1000 while the bar pushes the remaining sheets 1034 of the stack thereacross. Ribs 1044 are provided on the inner face of the upper shell 1036 of housing 1038 aside of a display window 1042, and the separated print is lifted and pressed against these ribs once the drawer has reached its outer end position. The lifting operation is performed by two wire spring brackets 1046 whose transverse portions 1048 engage the print; when the drawer is pushed home they are depressed by skids 1049 provided on the drawer and engaging control portions 1050 of the brackets. Two leaf springs 1052, too, contribute to the lifting of the print. It will be seen that the print is thereby deformed to assume an S-shape. As the print is clamped already by the innermost bracket it is thereby pulled off the catch hook and gets clear thereof. The leaf springs 1052 are mounted in recesses 1054 of the drawer skids, precede the skids upon the drawer's being pushed home, and serve as shock absorbers when hitting the control portions 1050. Referring now to Fig. 40 to 44 it is to be noted that only those ele¬ ments which are essential for the invention are illustrated and that the view are somewhat schematic. With regard to the cooperation between separator bar 1016, guide path 1060, step 1062 and support 1064 the publication W089/04991 is referred to. It will be recognized that in accordance with the present invention the separator bar ist provided with a projection 1070 which cooperates with an assembly of guide track 1072, step 1074 and support 1076 all dis¬ posed on a pair of ribs 1078 disposed on the housing bottom and located bilaterally of a plane of symmetry 1071. The two central supports are at a somewhat higher level than the outer supports 1064. Between each of the supports 1064 and the adjacent inner support 1076 there are auxiliary ribs 1080 which are level with the guide track 1072 but do not have a step. The projection defines an acute angle of preferably about 75° with the track 1072. This system operates as follows. It will be seen in Fig. 42 that upon start of the drawer withdrawal the separator bar 1016 has, with its projection 1070, climbed up the slopes 1082 to reach the guide track 1072 of the ribs 1078 thereby being bulged upwards against the elastic bias of the plastic material of which the bar consists. The shoes 1016 which are spring-supported in the sepa¬ rator bar remain in contact with their respective guide path 1060. The front face 1084 of projection 1070 is in contact with the adjacent trans¬ verse edges of the stack of prints from which the lowermost print 1032 is to be removed. It be now assumed that a longer print 1086 ("long" and "short" always refer to the dimension of the prints in direction parallel to the drawer reciprocation direction) superposes print 1032 and that the prints strongly stick together due to humidity or for any other reason. In result, at first the entire stack is pushed like a compact block outwards while being supported on ribs 1078 and auxiliary ribs 1080. When print 1032 has passed step 1074 with its trailing transverse edge it cannot drop behind this protecting step because it is still supported by the auxiliary ribs and because the force component produced by the projection 1070 towards support 1076 is insufficient to bend the print. This situation is illustrated in Fig. 43. Eventually, print 1032 is caught by hook 1010. Print 1032 now strongly resists further outwards displacement with the result that it bulges downwards under the force component mentioned above and finds rest on the support 1076. The second print 1086 now lacks support adjacent its center and also bulges some¬ what downwards thereby being stiffened in reciprocation direction. Any previously present curvature tending to place the trailing transverse edge of this second print between the trailing edge of print 1032 and step 1074 is thereby removed because photographic prints cannot be curved simultaneously about two orthogonal axes. Instead, it "rides" on print 1032 where the latter is supported by the auxiliary ribs and is conveyed outwards together with all other remaining prints. The steps 1062 allocated to the shoes 1018 are slightly set back re¬ lative to steps 1074 so that even if the removed print slightly turns the transverse edge of the latter can still contact the respective support 1064. It is to be noted that the bulging of the prints tends to lift their ends located in front of the shoes 1018 so that only the transverse edge caught by the hook may get beneath the shoes. This is indicated in Fig. 44 where the last phase of the separation is illustrated. In the embodiment of Fig. 45 through 48, rocker 1004 has a hook por¬ tion 1010 of a width which is substantial increased over that of Fig. 27 through 38. As mentioned above, the surface pressure exerted upon the print edge by the hooks should be kept to a minimum, and this pressure is sometimes extremely high, in particular if the drawer is withdrawn with high speed. However, with the enlarged hooks, the latter extend into the path of shoes 1018 as may be easily recognized when Fig. 31 and 46 are compared. This is of no importance for the outward drawer motion (cf. Fig. 47) while upon the inward stroke (Fig. 48) the shoe would hit the rocker under an unfavourable angle unless ramps 1011 are provided per¬ mitting a soft slide-up of the shoes 1018 first unto the ramp 1011 and then unto the upper face of rocker 1004. In Fig. 47, positions of the rocker relative to rail 1000 are marked respectively 1004a, 1004b, and 1004c; in Fig. 48 the rocker position prior to engagement of the shoe 1018 upon inwards motion of the drawer is indicated in broken lines.

Claims: PATENT CLAIMS 1. A device for cyclically rearranging a stack of substantially rectangular sheets, in particular photographic prints, said device com¬ prising: - a first frame member forming a housing, - a second frame member forming a drawer which may be displaced between an inner end position within said housing and an outer withdrawn end position, said drawer holding said stack so that a first pair of opposite sheet edges is substantially parallel to a drawer withdrawal di¬ rection and a second pair of opposite first and second transverse sheet edges extends substantially transverse to said direction, - means in one of said frame members for removing an individual sheet from remaining sheets of said stack upon drawer withdrawal, - means in the other of said frame members for holding said re¬ maining sheets while passing across said individual sheet, wherein at least one of said transverse sheet edges of said individual sheet may be overlapped by a second sheet belonging to said remaining sheets, said device further comprising: - first protection means for preventing said second sheet from operative interengagement with said removing means, and - second protection means for preventing said second sheet from being passed across, together with said individual sheet, by said holding means. 2. The device of claim 1 wherein said removing means engage said first of said transverse edges of said individual sheet so as to support said individual sheet. 3. The device of claim 2 wherein said holding means cooperate with a step and said second of said transverse edges of said individual sheet is disposed behind said step. 4. The device of claim 2 wherein said first protection means in¬ clude a control member which may be activated by at least one of said sheets which form said stack so as to deactivate said removing means for said first transverse edges of all sheets except said individual sheet. 5. The device of claim 2 including a first and a second engaging element respectively cooperating with said first and second transverse edges of said individual sheet, at least one of said engaging elements being positioned on an exposed surface of said individual sheet when said drawer is in said inner end position, and wherein at least one of said first and second protection means includes means for displacing an allo¬ cated one of said engaging elements across said surface towards an allo¬ cated one of said transverse edges of said individual sheet until said engaging element assumes a cooperation position, said displacing means being controlled by withdrawal of said drawer. 6. The device of claim 2 or claim 3 wherein said first protection means include a sensor element which senses a curvature of said indivi¬ dual sheet in the vicinity of said first transverse edge and for displa¬ cing said removing means into a position commensurate with a sensed cur¬ vature such that said first transverse edge only of said individual sheet contacts said removing means but not the first transverse edges of sheets belonging to the remaining stack. 7. The device of claim 2 or claim 3 wherein said first protection means include a pivotable sensor element having a sensor area abutting a surface position of said individual sheet spaced a predetermined dis¬ tance from said removing means which include at least one removing ele¬ ment disposed on said sensor element, thereby pivoting said removing element clear of a path to be passed by said first transverse edge of a second sheet adjacent said individual sheet. 8. The device of claim 3 wherein said second protection means in¬ clude blocking elements which in response to pressure and against spring bias allow access to said step. 9. The device of claim 3 wherein said second protection means in¬ clude stack support elements for spacing the stack from sheet support means, said individual sheet being elastically deformed towards said sheet support means by said holding means. 10. The device of claim 8 wherein said holding means include de¬ flecting means for deflecting a removing force transmitted upon said in¬ dividual sheet by said removing means so as to produce a force component for deactivating said blocking elements. 11. The device of claim 9 wherein said holding means include de¬ flecting means for deflecting a removing force transmitted upon said in¬ dividual sheet by said removing means so as to produce a force component for deformation of said individual sheet. 12. The device of claim 2 including a step behind which said second transverse edge of said individual sheet is disposed and wherein said re¬ moving means are spaced from said step by a distance at least equal to a sheet of maximum width between said first and second transverse edges. 13. The device of claim 1 wherein said second protection means in¬ clude means for deforming said sheets to assume a shape curved about an axis which extends parallel to said drawer withdrawal direction. 14. The device of claim 1 wherein said removing means are disposed laterally with respect to a central plane of symmetry extending parallel to said drawer withdrawal direction and intersecting said holding means.

Inventors: MAAG ARTHUR, MAAG, ARTHUR
Applicants: LICINVEST AG
Application year: 1992
Main classification: G09F11
IPC codes: G02B27, G03B23, G03B27, G09F11