EP0669275B1 - Loop buffer for tape transporting device - Google Patents

Description

The invention relates to a loop buffer with a variable loop length for one Transport device for strip material, in particular from individual sections to one continuous tape composite photographic footage, one each input-side and an output-side, possibly motor-driven pulley and a loop roller which is mounted so that it can move substantially vertically, the relative height of the pulleys determines the length of the loop

Loop buffer of this type (see e.g. DE 2 227 995 A) are used in belt transport devices for decoupling asynchronous transport speeds in different stations of the transport route used. A special area of application is generally referred to as a printer Processing facilities for photographic film material, in detail Machining sections have very different speed ratios. So there are sections in which the strip material is substantially uniform continuously advanced, and other sections (e.g. the notch station and the Exposure station), in which the strip material in larger or smaller steps is transported further.

In the loop buffers of the generic type which have become known so far, the Loop roll either relatively heavy or down by means of a spring loaded, with the spring travel covering the entire stroke range of the loop roller. This ensures reliable guidance of the strip material. In practice it happens with these loop buffers but with strong or abrupt changes in speed of the tape feed, as e.g. with intermittent feed, too strong Impacts and tension peaks in the strip material, which is a large Show risk of damage to the strip material and / or faults in the lead neighboring stations and are therefore highly undesirable.

The present invention is now intended to provide a loop buffer of the generic type be improved in such a way that the strip material is guided properly on the one hand and that, on the other hand, impermissible tensions in the strip material, even with abrupt ones Changes in speed can be safely avoided. In particular, the Loop buffer for and possibly composed of individual short strips also photographic film material with paper strips on the side be suitable.

The loop buffer according to the invention, which fulfills this task, is thereby characterized in that the loop roll via a relatively soft spring by an im substantially vertically freely movable ballast body is weight-loaded. In particular, the loop roller and its movable with it Bearing elements together an inert mass as low as possible, preferably only a few grams. By choosing a relatively soft spring, the Loop roll small but rapid changes in transport speed very much follow easily and quickly, whereby due to the low inertial mass of the moving parts Acceleration forces remain very low. Larger drift movements of the loop roll due to prolonged speed differences between in and Removal of the band material, on the other hand, causes the ballast to move, the weight load of the loop roll and thus that of the tape material applied tension always remains constant. The loop roll always stays in good condition Contact with the tape material and leads it properly. That with known Loop buffers notorious bouncing of the loop roll in the band material loop and the resulting blows to the strip material also occur under extreme conditions Conditions practically not.

According to a particularly advantageous embodiment, the loop roll comprises the Loop buffer according to the invention two or three parallel, coaxial loop wheels Slightly different diameters, depending on the thickness profile of the strip material are adjusted transversely to the longitudinal direction. This makes the loop buffer special suitable for photographic film material consisting of individual shorter strips is composed and possibly also with paper strips attached to the side is provided. Such film material usually lies in the processing of Reorder orders before and is known to have special requirements Transport devices, because the rigidity of the tape material over the length of the tape changes frequently and the side paper strips can easily come off.

Fig. 1

eine perspektivische Prinzip-Skizze der erfindungswesentlichen Elemente des Schlaufenpuffers,

Fig. 2

einen Schrägriss der wesentlichsten Elemente einer praktischen Ausführungsform des erfindungsgemässen Schlaufenpuffers,

Fig. 3

einen weiteren Schrägriss analog Fig.2, jedoch in anderer Blickrichtung und

Fig. 4

einen Vertikalschnitt durch die wesentlichsten Elemente der praktischen Ausführungsform des Schlaufenpuffers gemäss den Figuren 2 und 3, wobei sich die Schlaufenrolle in Einfädelstellung befindet.

Further advantageous and particularly expedient refinements and developments of the loop buffer according to the invention result from the dependent claims and the following description of an exemplary embodiment in conjunction with the drawing. In this show:

Fig. 1

2 shows a perspective principle sketch of the elements of the loop buffer essential to the invention,

Fig. 2

2 shows an oblique view of the most important elements of a practical embodiment of the loop buffer according to the invention,

Fig. 3

a further oblique tear similar to Figure 2, but in a different direction and

Fig. 4

a vertical section through the essential elements of the practical embodiment of the loop buffer according to Figures 2 and 3, wherein the loop roller is in the threading position.

The basic structure and the mode of operation of the loop buffer according to the invention are best seen in Fig.1. The loop buffer essentially comprises two parallel pulleys 1 and 2 and one vertically between the two pulleys and from movably guided loop roll 3. One of a first, not shown Processing station incoming strip material B, here in the form of a single use the shorter strips B1 with paper or plastic strips B2 on the side a continuous carrier tape B3 assembled into a longer tape photographic film tape, runs over the three to form a vertical loop Deflection and loop rollers 1, 2 and 3 to a second, also not shown Processing station. The feed of the strip material B is input and on the output side asynchronous by independent motor feed means, for example for example in that the input and output deflection pulleys 1 and 2 are motorized is drivable. Of course, the pulleys 1 and 2 can also be free run, and other known feed means can be provided for the strip material.

The loop roller 3 is rotatably mounted on a bearing slide 4, which itself on a vertical slide rod 5 is guided up and down. The bearing slide 4 and thus indirectly the loop roller 3 is via a coil spring 6 by a Ballast body 7 weighted, which is also guided on the slide rod 5 and lengthways it can move freely up and down. In addition, there is only one here with the double arrow 8 symbolized lift provided, by means of which the bearing carriage 4 and thus the Loop roller 3 in a lying above the level of the two deflection rollers 1 and 2 Threading position (Fig. 6) can be moved.

There are three along the displacement path of the loop roller 3 or the bearing slide 4 optoelectronic position sensors (light barriers) 9a, 9b and 9c arranged which Define vertical limit positions for the loop roll 3 and with a controller 10 interact, which depends on the position of the loop roller 3 Control signals 10a and 10b to the feed means (here the deflection rollers 1 and 2) for the Deliver the tape material in and out to the loop buffer to determine the loop length in the Keep loop buffers within specified minimum and maximum values. A Such regulation of the loop length is already conventional Loop buffers are known and therefore require no further explanation. Furthermore, the serve Position sensor still to control the process of the loop roll 3 in said Threading position and back to normal working position, what through the signal line 10c is symbolically indicated. Such an arrangement and control is also included conventional loop buffers known, so that there is also a more detailed explanation superfluous.

To thread the strip material B, the loop roll 3 is lifted by means of the lift 8 two pulleys 1 and 2 raised and the tape material by means not here shown guide members on the space between the two pulleys advanced until it is caught by the feed means on the output side. Thereupon the loop roller 3 is lowered into a working position by means of the lift 8, whereby forms the buffer loop. If now during operation Speed differences between the input side and the output side Belt feed result, so the loop length decreases or increases, whereby the Loop roll 3 follows accordingly, i.e. is raised or lowered. If the Loop role exceeds or falls below, limits, brakes or Depending on the case, the controller 10 temporarily stops the input or the output belt feed until the loop roll is again within the predetermined limit positions.

Short-term, rapid changes in speed and the resulting abrupt changes Deflections of the loop roller 3 are dimensioned by the relatively soft Coil spring 6 added. The ballast body 7 remains because of it Inertia practically stationary. Longer lasting speed differences lead (within the specified limits) to a drift movement of the loop roller 3 on or downwards, the ballast body 7 following the movement of the loop roller 3.

For a secure guidance of the strip material B, it is important that the Loop roll 3 is always in close contact with the band material loop. There is one certain minimum load of the loop roll is required, which results from the weight (the Mass) of the ballast 7 results and depending on the tape material B by some Attempts must be determined. For the photographic footage mentioned, as in processing photographic reorder orders is generally a ballast mass of about 150 to about 400 grams is suitable, the, as from The following illuminates, negligible mass of the loop roller 3 itself and the your firmly connected and movable parts (bearing elements etc.) not with is included. On the other hand, by abrupt speed changes like them Accelerating forces occur in particular with intermittent feed To keep it as low as possible, the mass of the loop roll 3 and that with it moving parts (bearing block 4 etc.) should be as small as possible. By correspondingly simple structure and choice of especially light construction materials, such as e.g. Plastic, this can be easily achieved. For the named application have e.g. Total masses from about 50 to about 70 grams as practical proven. The ballast body 7 with the Loop roller 3 coupling coil spring 6 to. On the one hand, it must be sufficiently soft be dimensioned to ensure rapid deflections of the loop roll safely and quickly to be able to catch, and on the other hand must not be too soft to "breakthrough" avoid. In practice, springs with a Proven spring constant in the range of about 0.2 to about 0.6 N / cm.

In Figures 2-4 is one for use in photographic processing lines particularly suitable practical form of realization of the inventive Loop buffers shown in detail, which is not the actual core of the Elements belonging to the subject of the invention are omitted for the sake of clarity are. It goes without saying that the loop buffer (although in principle possible) in the is generally not a physically independent unit, but usually in a processing line for the strip material or in the Belt material transport means this line is integrated.

According to FIGS. 2-4, the part of the loop buffer shown comprises a frame R, on which all with the storage of the loop roll and its movement connected elements are attached, so that the whole is a mechanical Unit forms as a whole between those usually in the processing line provided deflection rollers can be used, as can be seen from Fig.4. Of course, the deflection rollers could also be arranged on this frame R. be.

In the U-shaped frame R are parallel between the two, in the installed position horizontal legs two vertical slide bars 5a and 5b fixed stationary. Further two pulleys 83 and 84 are rotatably mounted in two bearing blocks 81 and 82, of which the upper (83) is rotatably driven by a motor, not shown. The both pulleys 83 and 84 are wrapped in a transport belt 85, whose two runs parallel to the slide bars 5a and 5b, i.e. run vertically. The two pulleys 83 and 84 and the conveyor belt 85 form together with the Drive motor, not shown, the aforementioned lift 8 for the vertical movement of the Loop roll 3.

On the two slide rods 5a and 5b is one of several plastic parts Compound, substantially approximately L-shaped bearing slide 4 sliding by means three bearing bushes 41, 42 and 43 guided smoothly, with the front Slide rod 5a two and a bearing bush is provided on the rear slide rod 5b. On the bearing sled 4, the loop roll designated here as a whole is free rotatably mounted. Another bearing carriage 44 is located just below the mentioned bearing slide 4 and is on one strand of the conveyor belt 85th clamped. The bearing carriage 44 engages under the bearing carriage 4, so that the Bearing carriage 4 can be moved upwards by means of the transport belt. The Downward movement of the bearing slide 4 is driven by gravity alone.

On the bearing slide 4 there is a flat one just below the loop roller 3 Fixed guide element 34, which in the threading position shown in Figure 4 Loop roller 3 the space between the two deflection rollers 1 and 2 bridged.

The cylindrical ballast body is freely displaceable on the rear slide rod 5b 7 led. It is supported by the relatively soft coil spring 6 already mentioned Storage carriage 4 and thus loads the loop roller 3 indirectly with its weight.

On the rear wall of the frame R are three in three different vertical positions Arranged light barriers 9a, 9b and 9c, which in the manner already mentioned as Serve position sensors for the vertical position of the loop roll 3. You work with one slat 45 fastened together on the bearing slide, which is between the two Legs of the light barriers moved.

The loop roller 3 here consists of three parallel loop wheels 31, 32 and 33, the sit on a common shaft 35. The two loop wheels 31 and 32 have slightly stepped diameter, the third loop wheel 33 is a simple one cylindrical roller. The diameters of the individual loop wheels are based on that Cross-thickness profile of the strip material to be transported coordinated, resulting in a results in optimal guidance. This is particularly important if it is Tape material around such a "difficult" material as that often found in the photo laboratory Individual film strips with and without side information carrier strips using a continuous carrier tape is composite tape material. Are preferred the deflection rollers 1 and 2 are designed analogously. This has the added advantage that with the comb-like design of the guide element 34 shown, the distance can be bridged better between the two deflection rollers in the threading position.

Claims (10)

1. Loop buffer with variable loop length for a transport appliance for strip material (B), in particular photographic film material assembled from individual sections (B1) to form a continuous strip (B), having one possibly motor-driven deflection roller (1, 2) respectively at the inlet end and the outlet end and a loop roller (3) which is supported so that it can be moved substantially vertically between them and whose vertical position relative to the deflection rollers (1, 2) determines the length of the loop, characterised in that the loop roller (3) is gravitationally loaded, via a relatively weak spring (6), by a ballast body (7) guided so that it can move freely in a substantially vertical direction.
2. Loop buffer according to Claim 1, characterised in that the loop roller (3), and the support elements (4) which move together with it, together exhibit the smallest possible inertial mass of preferably only some few grams.
3. Loop buffer according to one of the preceding claims, characterised in that the loop roller (3) is movably supported on slide bars (5a, 5b).
4. Loop buffer according to one of the preceding claims, characterised in that the ballast body (7) is movably supported on a slide bar (5b).
5. Loop buffer according to one of the preceding claims, characterised in that the loop roller (3) can be moved to above the level of the deflection rollers (1, 2) for the operation of threading in the strip material (B).
6. Loop buffer according to Claim 5, characterised in that powered drive means (8) are available for the vertical adjustment of the loop roller (3).
7. Loop buffer according to one of the preceding claims, characterised in that position sensors (9a, 9b, 9c) for the vertical position of the loop roller (3) are present.
8. Loop buffer according to Claim 7, characterised in that a control system (10) is provided which interacts with the position sensors (9a, 9b, 9c) and which, when the specified vertical limiting positions are exceeded, generates control signals (10a, 10b, 10c) for the feed transport and removal transport of the strip material (B).
9. Loop buffer according to one of the preceding claims, characterised in that loop roller (3) comprises two or three parallel and coaxial loop wheels (31, 32, 33).
10. Loop buffer according to Claim 9, characterised in that the loop wheels (31, 32, 33) have different diameters, the diameters being matched to the transverse thickness profile of the strip material (B).

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