Abstract:
A thread controlling assembly containing an oscillating operable lifting device with at least one carrier for a warped thread of a weaving machine, and a control element which can be actuated using an actuator in order to selectively bring the thread in contact with the carrier. The control element is supported independently of the lifting device. Additionally, the control element need only be moved by an incremental switching amplitude for guiding the thread into and out of the carriers.

Description:
BACKGROUND OF THE INVENTION 
     I. Technical field 
     The invention relates in general, to a thread control device for selectively controlling an oscillating transverse movement of a thread, in particular a warped thread of a weaving machine, having at least one lifting device which can be driven in an oscillating fashion, a carrier for a thread and at least one control means which can be actuated to bring the thread selectively into engagement with the carrier. 
     II. Background Information 
     There are many known thread control devices, particularly in shedding mechanisms, for optionally controlling an oscillating transverse movement of a thread. 
     In a first type of such thread control devices, the threads are controlled indirectly, the thread being moved only when it is selected. For this purpose, threads are firmly drawn into eyelets of healds and guided, the healds being moved in a programmed fashion via connecting means with the aid of upstream jacquard machines, heald looms and treading machines. It is easy to establish in this case that selective movement of the thread requires a multiplicity of components and a large stroke for them, and this necessarily has a very negative influence in many regards. Thus, in particular, the speed of the shedding mechanism is very limited because of the high mass forces. Further marked disadvantages of the known thread control devices are, for example, a high wear level, strong vibration, loud noise, a large space requirement because of the complicated devices, and poor ergonomics and the like. Finally, they are also relatively expensive, because of the complicated design. 
     A second type of such thread control devices is disclosed in U.S. patent application Ser. No. 09/043,542 filed Mar. 19, 1998. This thread control device has a lifting device, which can be driven in an oscillating fashion, having at least one carrier for the thread, as well as at least one control means which can be actuated by means of an actuator in order to bring the thread selectively into engagement with the carrier of the lifting device. These control means are arranged, assigned directly to the carrier, on the lifting device and are moved to go up and down with the latter. This results in various disadvantages. Since the lifting device must contain not only the carrier but, in particular, also the control means and the actuator, it has a relatively large volume. This thread control device is ill-suited to a weaving machine with a high warp count. Moreover, the moving parts are of relatively large mass and must, in addition, be moved over the entire stroke of the lifting device. The co-movement of the actuator further requires a moving interface with the supply of power and program data, which is relatively complicated, expensive and prone to wear. A thread has to be drawn in very carefully, in order to prevent parts from being bent, and thus a functional failure associated with corresponding repair costs. Despite good accessibility, it is time consuming and costly to draw in a thread. Finally, because of the relatively high mass forces and the sensitivity of the electronic system integrated into the moving parts, such a thread control device can be operated only at a relatively low speed. 
     DISCLOSURE OF THE INVENTION 
     SUMMARY OF THE INVENTION 
     It is the object of the invention further to provide an improved thread control device. 
     The object set is achieved according to the invention by control means arranged independently of the lifting device for the carrier such that the control means moves the thread selectively toward and away from the carrier in an oscillating fashion by an incremental “switching amplitude”, which may also be referred to as a “switching variable”, and is represented in FIG. 24 of the drawings by the variable “S”. 
     By virtue of the fact that the control means are arranged independently of the carrier and thus of the lifting device, the lifting device is relieved of mass and sensitive control elements and can be configured exclusively in accordance with optimal points of view for the lifting movement. The control means, by contrast, are arranged virtually fixed, that is to say they must not also execute the lifting movement of the lifting device, but can be exclusively limited and concentrated on executing the switching amplitude for the purpose of laying in and removing the thread at the carrier in an oscillating fashion. The fixed arrangement also permits drive energy and control signals to be fed in a simple way independently of wear, as well as permitting a large degree of flexibility in the control possibilities. Further decisive advantages result from this such as, on the one hand, smaller drive motors for the lifting device and, on the other hand, smaller actuators for the control means, a lesser energy requirement for the drive means, and thus not only a more cost effective production but also a more cost effective operation despite higher power. This also leads to less development of heat, which finally also has the effect of simplifying and lowering the cost of air conditioning for the operating rooms in which such devices are set up. Furthermore, such a device is also easier to access, and this facilitates laying in the thread. This is supported further by the insensitivity of the components. 
     The use of a novel thread control device in a shedding mechanism for warp thread control in a weaving machine provides substantial advantages there of the type mentioned above. 
     The substantially lower number, in particular, also of the moving components, and thus a reduction in the moving masses permits higher drive speeds and thus higher production performances, it being the case, nevertheless, that there is a large reduction in wear and in the emission of noise and vibration by comparison with conventional thread control devices, in particular shedding mechanisms of a weaving machine. The invention opens up the possibility of operating the thread control device, in particular the shedding mechanism, and thus also the connected weaving machine at very high speeds, for example of 5000 revolutions per minute and more. 
     The elimination of the otherwise customary upstream control devices and of the various connecting elements otherwise required results in further substantial advantages. The fact that a weaving machine equipped with the thread control device according to the invention requires no built-on accessories for upstream shedding mechanisms such as jacquard machines, produces for the weaving machines a large saving in space requirement over the weaving machine, and thus an improvement in the supervision and accessibility of the entire weaving machine, the result being an ergonomically important improvement in the supervision and handling, and thus in the workplace at a thread control device, in particular a shedding mechanism. The work of adjustment and maintenance can therefore be performed in a safe and easy manner. 
     Advantageous embodiments of the thread control device are described hereafter. 
     There are various possibilities for constructing the control means. Thus, said possibilities can consist, however, in providing an electric pulse to the threads to be controlled in order to defect the latter toward the carrier by the switching amplitude. However, such a construction is possible only if the thread reacts to a current pulse. In one embodiment which is more advantageous, a control slot ensures a shaped closure capturing of the thread which is also independent of the property of the thread. A development according to a further embodiment is expedient in order to permit guidance along the entire transverse movement or the stroke of the thread. 
     The lamella-like construction of the control means which covers the carrier likewise having a lamellae-like construction produces a particularly space-saving design, which improves its use, in particular concerning the warp thread control of a weaving machine. In this case, the control means can be developed with two parallel lamellae which enclose lamellae-like carriers between them or at least one further lamellae enclosing a further carrier. 
     In accordance with another embodiment, the carrier can be effective over the entire transverse movement of the thread. However, a further embodiment having first and second oppositely directed carriers is more advantageous, providing not only a reduction in the stroke path of a carrier, but also an improvement in the control possibilities. 
     Particularly preferred is an embodiment of the thread control device, according to which the carrier has a carrier hook, effective only in one direction of movement, for shaped closure driving of the thread. In the other direction of movement, the return preferably proceeds in a forced fashion, it being possible for the residual stress of the thread to be sufficient. If appropriate, further additional tensioning devices can be present. In specific cases, it is possible for the thread control device to have a carrier which permits shaped closure driving in both directions of movement of the thread. 
     There are numerous possibilities for constructing and arranging the carrier. The carrier hook is arranged at the end of the spring tongue and preferably has one run-on guide outside the carrier part. The carrier hook has a thread rejector at the free end, or two carrier hooks pointing away from one another, each having control means for laying in a thread. 
     They are also given as possibilities for constructing the actuator, a few which are particularly preferred. For example, the actuator may include a piezoelectric switching device or may be constructed as a piston/cylinder unit actuated by a fluid such as air. The actuator may also be constructed as an electromagnet. There are also disclosed a number of possibilities for constructing the actuator. In one case, the actuator can be activated in a drive direction, and can be returned in the other direction by means of a spring. 
     The control means can be arranged to be capable of being pivoted by the switching amplitude, it preferably being possible for this arrangement to be made on a support rail. The control elements can be arranged in pairs and mounted pivotally on a common support which is fastened to the support rail and has a swinging arm which pretensions the control elements against the actuator. The control element alternatively may have a control stop and a biasing spring which pretensions the control stop against a preferably piezoelectric switching device which releases the control stop in the switching state and brings the control element into engagement with an oscillating actuator. 
     However, in a preferred embodiment of the thread control device, the control element which can be displaced going to and fro in its longitudinal direction permits numerous variants in terms of arrangement and drive. Thus for example, the actuator can be arranged at the lower end of the control element. It is also possible to design the device in which the control element moving to and fro in the longitudinal direction is pretensioned in one direction at the lower end by means of a return spring and is connected at the upper end with the actuator by means of a connecting element such as a cord. In such a thread control device, the actuator does not have to execute the entire stroke path, but only a part corresponding to the switching amplitude, with the result that the device can be constructed in a substantially simpler and smaller way by contrast with the jacquard device, and that only a smaller amount of energy is required to surmount the switching path by comparison with the existing jacquard devices. 
     Particular simple and compact designs of the thread control device are possible. For example, the control element moving to and fro in the longitudinal direction may cooperate with a drive element also moving to and fro in the longitudinal direction and against which drive element the thread control is pretensioned by means of a spring. The control element also has a retaining stop with which a controllable switching device, preferably a piezoelectric switching device, can cooperate in such a way that the control element follows the movement of the drive element in the event of an ineffective switching device, and is retained in a position in the event of an effective switching device. 
     It is expedient for the carrier to be arranged on a lifting rail of a lifting device. 
     The thread control device is suitable for the most varied applications and so, for example, for optionally presenting a weft thread insertion member with weft threads of different colors and qualities for gripping. However, it is particularly advantageous if the thread control device is made up of components of a shedding mechanism of a weaving machine, a multiplicity of the thread control devices being present for controlling the warp threads of the weaving machine. A dedicated actuator can be present for each control element in order to achieve the greatest possible multiplicity of control possibilities. The design in which the control elements are combined into groups to be driven by a common actuator can also be advantageous for simpler cases. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Exemplary embodiments of the thread control device according to the invention are described in more detail below with the aid of diagrammatic drawings, in which: 
     FIG. 1 shows a first thread control device in the shedding mechanism of a weaving machine, in side view; 
     FIG. 2 shows the thread control device of FIG. 1 on a larger scale; 
     FIG. 3 shows the thread control device of FIG. 2 in the section III—III of FIG. 2; 
     FIGS. 4 to  20  show a diagram of the movement of the thread control device of FIGS. 1 to  3  in various control phases in accordance with FIGS. 5 to  20 , the carriers being represented in an open fashion in FIGS. 5 to  20 , that is to say for the purpose of better understanding, the part of the control means situated in the foreground has been omitted; 
     FIG. 21 shows the thread control device of FIGS. 1 to  20 , working from the basic position into a high position; 
     FIG. 22 shows a third thread control device having a piezoelectric control; 
     FIG. 23 shows a fourth control device having a control element and two carriers, working from a middle basic position; 
     FIG. 24 shows a fifth thread control device having a control element, oscillating in the longitudinal direction, comprising two lamellae and assigned carriers; 
     FIG. 25 shows the thread control device in section XXV-XXV of FIG. 24, on a larger scale; 
     FIG. 26 shows a sixth thread control device similar to FIGS. 24 and 25, but having a control element comprising three lamellae and assigned carriers; 
     FIG. 27 shows the thread control device of FIG. 26 in section XXVII—XXVII on a larger scale; 
     FIG. 28 shows a seventh thread control device similar to FIGS. 24 to  27  and having an actuator, in a diagrammatic representation; 
     FIGS. 29 to  33  show various control phases of the thread control device in FIGS. 24 to  28 ; 
     FIG. 34 shows the movement diagram for the movement phrases of FIGS. 29 to  33 ; 
     FIG. 35 shows the thread control device of FIGS. 24 to  33  in the shedding mechanism of a weaving machine in the open shed position; 
     FIG. 36 shows the shedding mechanism of FIG. 35 in closed shed position; 
     FIG. 37 shows a weaving machine having a thread control device in accordance with FIGS. 35 and 36 and having individual repeat control, in a view onto the front side; 
     FIG. 38 shows a further weaving machine having thread control devices in accordance with FIGS. 35 and 36, the actuators driving a plurality of control elements in terms of repeat; 
     FIG. 39 shows an eighth thread control device similar to FIGS. 24 to  27  and having a modified actuator in a shedding mechanism in open shed position; 
     FIG. 40 shows the shedding mechanism of FIG. 39 in closed shed position; 
     FIG. 41 shows the actuator of the shedding mechanism of FIGS. 39 and 40, constructed as a pneumatic piston/cylinder unit; 
     FIG. 42 shows the actuator of the shedding mechanism of FIGS. 39 and 40, designed as an electromagnet; 
     FIG. 43 shows a ninth shedding mechanism having thread control devices similar to FIGS. 24 to  27 , having modified actuators; 
     FIG. 44 shows the actuators of the shedding mechanism of FIG. 43, on a larger scale; 
     FIG. 45 shows the actuators of FIGS. 43 and 44 in a modified form in the section XXXXV—XXXXV of FIG. 47, in high position; 
     FIG. 46 shows the actuators of FIG. 45 in low position; 
     FIG. 47 shows the arrangement of the control elements of FIGS. 45 and 46, in plan view; and 
     FIG. 48 shows a weaving machine having thread control devices in accordance with FIGS. 38 to  47  and direct drive of the control elements, in a view onto the front side. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows the diagrammatic design of a weaving machine. Warp threads  4  are drawn off from a warp beam  2  and run via a tensioning device  6  to a first warp guide  8 , and further to a second warp guide  10 , between which warp feelers  12  are arranged. From the second warp guide  10 , the warp threads  4  run via a plurality of thread control devices  14 , which are combined to form a shedding mechanism  13  and open the warp threads  4  to form a weaving shed  16 , to a weaving station  18  at which weft threads  20  are inserted into the open weaving shed  16  and beaten at a fell  24  by means of a weaving reed  22 . The woven web  26  thus produced is guided via the fabric guide  28  of a drawing-off device  30  to a fabric roller  32  and wound on there. 
     The shedding mechanism  13  is formed from individual thread control devices  14  represented in detail in FIGS. 2 and 3, and includes a lifting device  34  having a lifting rail  36  which can be moved up and down, for example via a connecting rod  38  by a driven eccentric  40 . Lined up on the lifting rail  36  are carriers  42  which are constructed like lamellae and have on mutually opposite sides spring tongues  44  at whose free ends there is arranged in each case a carrier hook  46 ,  48  for gripping one warp thread  4   a ,  4   b  each. Each carrier hook is provided at the free end with a run-on guide  50 , in order to facilitate engagement of the warp thread. Positioned above the carrier hooks  46 ,  48  is a thread rejector  52  whose purpose is to prevent undesired engagement of warp threads on the carrier hook  46 ,  48 . 
     For each carrier hook  46 ,  48 , each carrier  42  is assigned control elements  54 ,  56  which can be controlled by means of an actuator  58 ,  60  in order to bring an assigned warp thread  4   a ,  4   b  into engagement with the carrier hook  46 ,  48  of the carrier. The actuators  58 ,  60  are connected via a line  62  to a control device  64  which the actuators control in terms of pattern in accordance with the web to be produced, doing so in a way which, although not represented in more detail, is known. Each control element  54 ,  56  comprises two control lamellae  54   a ,  54   b  and  56   a ,  56   b , respectively, which enclose the carrier  42  between them. The control elements  54 ,  56  and/or their control lamellae  54   a ,  54   b  and  56   a ,  56   b , respectively, are mounted on a common support  66  such that they can pivot about bolts  68 , the pivoting path corresponding only to the switching amplitude required to insert the warp thread into the carrier and bring it out of it. The support  66  is lined up on a fixed support rail  70  and includes spring arms  72  which operate in each case with a stop  74  between the control lamellae  54   a ,  54   b  and  56   a ,  56   b  respectively, and pretension the latter against the actuator  58 ,  60 . 
     As emerges from FIGS. 1 and, in particular  2  to  20 , the control elements include slots  76  which, in the basic position of the warp threads  4   a ,  4   b  are constructed as narrow control slots  78  which merge in the lifting direction into wide guide slots  80 . 
     The mode of operation of the shedding mechanism follows very clearly from FIGS. 1 to  20 . The basic position of the warp threads is determined by the straight connection between the second warp guide  10  and the fabric guide  28 . This basic position also corresponds to the high position of the warp shed from which the warp threads  4 ,  4   a ,  4   b  are brought selectively by the stroke H into the low position, as is to be seen from the figures. A warp thread  4 ,  4   a ,  4   b  is driven only if the warp thread is brought by means of the associated control element  54 ,  56  into engagement with the associated carrier hook  46 ,  48  in the high position thereof (FIGS. 5,  9  and  17 ). For this purpose, an appropriate actuator  58 ,  60  is activated via the control device  64 , and pivots the associated control element  54 ,  56  against the associated carrier hook  46 ,  48 , with the result that upon the downward movement of the carrier  42  the warp thread is driven by the carrier hook  46 ,  48  and brought into the low position (FIGS. 1,  2 ,  7 ,  11  and  19 ). The warp thread is returned from the low position into the high position with the upward movement of the carrier  42  primarily by the residual stress of the warp thread. The upward movement can be further supported by laying the warp thread on the lifting rail, which is arranged directly below the carrier hook. The carrier hook could, if appropriate, also be constructed as a double hook  48   a , as is indicated by dashes in FIG.  2 . The warp thread is directed out of the carrier hook  46 ,  48  when the carrier  42 , and thus the warp thread  4   a ,  4   b , has reached the basic position. The actuator  58 ,  60  is then switched to be inactive, as a result of which the control element  54 ,  56  is pivoted back, under the influence of the pretensioning of the spring arm  72 , into the basic position (FIGS. 13 to  16 ), in which the warp threads cannot be driven by the carrier  42 . 
     The carrier  42  is equipped in the present example with two carrier hooks  46 ,  48 , and two control elements  54 ,  56  are assigned correspondingly, with the result that one carrier can move two warp threads  4   a ,  4   b  selectively out of the upper shed position into the lower shed position, as shown, in particular, by the diagram in FIG.  4  and the associated phase drawings of FIGS. 5 to  20 . It is therefore necessary to arrange on a lifting rail  36  only half as many carriers  42  as there are warp threads present, and on a support rail  70  a number of control elements  54 ,  56  which corresponds to the number of the warp threads. The carriers  42  constructed like lamellae and control elements  54 ,  56  are configured to be correspondingly thin and can, for example, be 0.1 to 0.5 mm thick. If appropriate, it may be expedient to distribute the required number of carriers  42  and control elements  54 ,  56  over two and more lifting rails  36  and support rails  70 . 
     As shown by the above embodiments, no spring returns are required with the novel shedding mechanism, and the components required to control the warp threads are reduced to a minimum because of the direct control of the warp threads, as a result of which there is a very considerable reduction in the drive forces by comparison with conventional devices. This leads, on the one hand, to a substantial saving in energy and, on the other hand, it opens up the possibility of operating such a weaving machine with a substantially higher speed of, for example, 5000 or more revolutions per minute. 
     FIG. 21 describes a thread control device  14   a  which corresponds essentially to that of FIGS. 1 to  20 , the thread control device being arranged, however, not below the web prescribed by the warp threads  4   a ,  4   b  but above it, with the result that the neutral position of the warp threads corresponds to the lower shed position, and the warp threads are deflected into the upper shed position by means of the carrier  42 . 
     In the shedding mechanism represented in FIG.  22  and formed from thread control devices  14   b , the carriers  82  are lined up on a lifting rail which forms part of a metal heald frame  84  which is moved up and down in a known way. The carriers, in turn, include carrier hooks  46 ,  48  and projections  86 ,  88  which serve to support the return of the warp threads into the initial position. Assigned to the carrier  82  or the carrier hooks  46 ,  48  are control elements  90 ,  92  which, in turn, include a slot  76  having a control slot  78  and a guide slot  80 , and are mounted pivotably on a support rail  94 . Each control element has an actuating arm  96  on the side opposite from the warp threads  4   a ,  4   b . Each actuating arm  96  includes a control stop  98  and a biasing spring  100 , which pretensions the control stop  98  against a switching device  102 , a so-called flexural vibrator, which is at an electric potential thereto. If the switching device  102  is not activated, the control stop  98  rests on said switching device and the control device remains in the neutral basic position. If, however, the switching device  102  is activated via a line  104  by means of the control device  64 , the switching device  102  pivots into the position shown by dashes, and the switching device  90  can pivot under the influence of the biasing spring  100  and share in the movement of an actuator  106  in the form of a driven control strip which engages in a driving groove  108  at the lower end of the actuating arm  96 . This driving groove  108  has a width such that it can move freely when the actuating arm  96  is stopped in the basic position by the switching device  102 . With the switching device  102  activated, the biasing spring  100  pretensions the actuating arm  96  against the control strip  106 , with the result that the actuating arm shares in the movement of the control strip  106 , the control element  90  or  92  thereby engaging the corresponding warp thread  4   a ,  4   b  with the associated carrier hook  46 ,  48 . The control stops  98 a to  98 n represented by dashes in FIG. 22 correspond in each case to a control element following in the sequence, which respectively cooperates in turn with a dedicated switching device (not represented). 
     FIG. 23 describes a thread control device  14   c , in which a warp thread  4  is assigned two carriers  110  and  112  which move the warp thread from the neutral position of the warp threads, which corresponds to the middle shed position, into the upper shed position or into the lower shed position, respectively. The carriers  110 ,  112  are arranged on corresponding lifting rails  114 , 116  and in each case have a carrier hook  120 ,  122  at the end of a spring tongue  118 . Assigned to the two carriers  110 ,  112  is a common control element  124  which is mounted pivotably on a support rail  126  and has on the side opposite from the warp thread  4  an actuating arm  128  which cooperates with two actuators  130 ,  132  which act opposed to one another and pivot the control element  124  against one or other of the carriers  110 ,  112 . The control element  124  is provided, in turn, with a slot  134  for controlling the warp thread, which is constructed in the neutral position of the warp thread  4  as a narrow control slot  136  which then merges both upward and downward into wide guide slots  138 , 140 . This thread control device functions similarly to the thread control device described at the beginning. 
     FIGS. 24 and 25 show a further thread control device  14   d  having a control element  140  to which carriers  142 , 144  having carrier hooks  146  are assigned on each side. The carriers  142 ,  144  run in opposite directions and move downward or upward, respectively, from the middle position shown in FIG.  24 . The control element  140  includes a slot  148  which is constructed in the middle position as a control slot  150  and which is adjoined by guide slots  152  on both sides. The control slot  150  is arranged at an angle relative to the longitudinal direction of the control element  140  in such a way that when the latter moves longitudinally in an oscillating fashion, the control element is moved by the switching amplitude S, as is represented by dashes in FIG.  24 . When the control element is moved from the position represented by full lines in FIG. 24 into the position represented by dashes, the warp thread  4  is transferred from the carrier region of the left-hand carrier  142  into the carrier region of the right-hand carrier  144 , with the result that when executing its lifting movement by means of the lifting rail  154  of the lifting device (not represented in more detail) the latter carrier can be transferred from the middle position into the upper shed position. As emerges, in particular, from FIG. 25, the control element  140  is constructed like a lamella and comprises the control lamellae  140   a  and  140   b  which enclose between them over a portion of their width the carriers  142 , 144  which are likewise constructed like lamellae. 
     FIGS. 26 and 27 show a thread control device  14   e  which corresponds to that of FIGS. 24 and 25, the control element having a further control lamella  140   c , with the result that the carriers  142 ,  144  are respectively arranged between mutually separated control lamellae  140   a ,  140   b  or  140   b  and  140   c . Consequently, the control lamellae can be of wider design and can have a larger degree of coverage with the control lamellae, and thus an improved guidance. In this case, the carriers  142 , 144  can have a section  156  which covers the carrier hook  146  and which cooperates in the manner of a double hook  146   a  to return the warp thread  4  from the upper or lower shed position and thus support the active control of the warp thread. In the middle shed position represented in FIG. 26, the widened sections  156  of the carriers  142 ,  144  form a gap  158  which supports the transfer of the warp thread along the control slot  150  out of one switching position into the other switching position. 
     FIGS. 28 to  33  show the further design and driving of the thread control devices  14   f  according to FIGS. 24,  25  and  26 ,  27 , respectively, on the one hand, and different phases of the movement cycle during control of the warp thread, on the other hand. In the case of the control elements  140  shown in FIGS. 28 to  32 , the control element  140  is controlled by means of an actuator  160  which is driven pneumatically and to which the control element  140  is connected via a harness cord  162  which is guided from the actuator  160  via a cord board  164  to the control element  140 . The actuator serves primarily for the upward stroke, while the return movement is performed by a return spring  166  which is connected to the lower end of the control element  140 , which end is guided by a guide  168 . The movement cycle of the carriers  142 ,  144  is represented in the movement diagram of FIG.  34 . In accordance with FIG. 29, the warp thread  4  is moved out of the middle shed position into the lower shed position in accordance with FIG. 30 by means of the left-hand carrier  142 . From this position, it then passes again into the middle shed position in accordance with FIG. 31 when the carrier  142  moves back, the warp thread  4  being transferred in the right-hand carrier  144  by means of the control slot  150  of the control element  140 . Said carrier  144  drives it into the upper shed position in accordance with FIG. 32, from which it then passes again into the middle shed position in accordance with FIG. 33 by means of the right-hand carrier  144 . 
     FIGS. 35 and 36 show the arrangement of a plurality of thread control devices  14   f  in accordance with FIGS. 28 to  33  in a shedding mechanism  170  of a weaving machine, it being possible for such thread control devices to be arranged both in a row one behind another and in a plurality of rows next to one another, depending on the count of the web  26  to be produced or on the count of the warp threads  4   a ,  4   b  to be controlled. FIG. 35 shows the shedding mechanism in open shed position, the waft thread  20  being inserted into the weaving shed  16  and then beaten at the fell  24  by means of the weaving reed  22 . The shedding mechanism is represented in the closed shed position in FIG.  36 . 
     FIG. 37 shows the front view of a weaving machine having thread control devices  14   f  in accordance with FIGS. 35 and 36 and the shedding mechanism  170 . As emerges from FIG. 37, the weaving machine includes a machine frame  172 , in which the shedding mechanism  170  is arranged with the thread control devices  14   d ,  14   e  and  14   f , and which serves to control warp threads (not represented in more detail) directly in terms of repeat. Each control element  140  is pretensioned downward via the return spring  166  and connected, via the harness cord  162 , which is guided through the cord board  164 , to a selecting device  174  which contains the actuators  160 . FIG. 38 shows a further weaving machine, in which an actuator  160   a  of the selecting device  174   a  and the shedding mechanism  170   a  simultaneously operates a plurality of control elements in accordance with a warp repeat T. 
     FIGS. 39 to  42  show a further exemplary embodiment of a shedding mechanism  176  having thread control devices  14   g  which are designed according to the principle of the thread control devices  14   d  and  14   e  in FIGS. 24 to  27 , but have modified actuators  178 . For this purpose, the control elements  140  are arranged at the lower end in a guide  180  and connected via connecting elements  182  to the actuators  178 , which are situated lower down. These then drive the control elements. In accordance with FIG. 41, such an actuator  178   a  can be constructed as a pneumatic piston/cylinder unit. A piston  184  connected to the connecting element  182  is pretensioned in the low position in the cylinder  186  by means of a return spring  188 . Compressed air is supplied via the feed line  190  and the piston, and thus the control element, are raised. A further example of an actuator  178   b  is shown in FIG.  42 . In this case, the actuator is constructed as an electromagnet and has in a housing  192  a coil  194  to which control current is applied via lines  196 . A permanent magnet  198  is arranged displaceably in the coil  194  and connected to the control element  140  via the connecting element  182 . The shedding mechanism is represented in open shed position in FIG. 39, and in closed shed position in FIG.  40 . 
     FIGS. 43 and 44 show a further shedding mechanism  200  having thread control devices  14   h  according to the principle of the thread control devices of FIGS. 24 to  27 , but with further modified actuators  202 . For this purpose, the control elements  140  each have at the lower end a guide element  204  which is guided moving up and down in a guide  206 . Lease knives  208  which move up and down and in each case cooperate with a carrier part  210  on the control element  140  serve to drive the control elements. The biasing spring  212  in the guide  206  pretensions the control element  140 , and thus the carrier part  210 , against the lease knife  208 , with the result that the control element  140  can follow the oscillating movement of the lease knife. Arranged on the underside of the guide  206  is a control plate  214  which carries piezoelectric switching devices  216  which, in the unswitched state, ensure the free movement of the guide element  204 , and thus of the control element, and in the switched, that is to say activated state cooperate with a shoulder  218 , with the result that the carrier part  210  and thus the control element  140  can no longer follow the lease knife  208 . This retains the control element in one switching position, with the result that an associated warp thread  4  can no longer be passed on from one carrier  142  to the other carrier  144 , and can thus no longer change from the low position into the high position, and vice versa. 
     FIGS. 45 to  47  show a further embodiment of a thread control device  14   i , which corresponds tog the thread control device  14   h  of FIGS. 43 and 44, although in this case the actuators  202   a  have control plates  214   a  with two rows, situated one under another, of switching devices  216 ,  216   a  which come into use alternately viewed in the longitudinal direction of the lease knife  208 . Consequently, the guide elements  204   a  differ and have shoulders  218 ,  218   a  at appropriately offset positions. This permits a high package density of the thread control devices, and thus a high porter per centimeter. The lease knives are represented in high position in FIG.  45  and in low position in FIG. 46, individual switching devices  216 ,  216   a  being shown in the activated, that is to say deflected state in which they cooperate with the shoulders  218 ,  218   a  of the guide elements  204   a.    
     The weaving machine represented in FIG. 48 includes a shedding mechanism  200  in accordance with FIGS. 39 to  43  having thread control devices  14   g ,  14   h ,  14   i  in accordance with FIGS. 39 to  47 . In this case, the guide  206  with the actuators  202  is arranged below the weaving region  220  in the machine frame  222 , with the result that the weaving region is freely accessible from the top side. 
     In the above exemplary embodiments, the thread control devices are shown in each case in conjunction with the control of warp threads for shed formation in a weaving machine. The thread control devices can, however, also serve to control other threads for other purposes, in particular for selecting weft threads which are either fed separately from the warp threads or, in particular, similarly to the warp threads.