JP2796366B2 - Loom weft insertion control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a weft insertion control device for a loom that can continue a stable weft insertion operation in a jet loom even if the flight characteristics of a weft yarn fluctuate.

Prior art In jet looms, especially air jet looms,
Weft insertion may become unstable due to changes in the flight characteristics of the weft used for weaving. It is considered that the main cause is that the air resistance of the yarn changes because the yarn physical properties such as the thickness of the yarn and the size of the feather vary in the length direction of the weft.

In particular, inside the yarn feeder serving as a supply source of the weft, since the flight characteristics of the weft constituting the yarn feeder gradually change, one of the yarn feeders is consumed, and the weft becomes a new yarn feeder. In the case of so-called yarn change, the flight characteristics of the weft are recognized to change stepwise and discontinuously, and a technique corresponding to this has already been proposed ( For example, JP-A-58-18446 and JP-B-63-19341).

All of these technologies assume that the flying characteristics fluctuate when changing the yarn supply, and actively change the injection pressure on the weft insertion main nozzle and sub-nozzle so as to eliminate this. Thus, a stable weft insertion operation is to be continued.

Also, by monitoring the mechanical angle of the loom at which the inserted weft reaches the non-weft insertion side of the woven fabric (hereinafter referred to as the arrival angle of the weft), fluctuations in the flight characteristics of the weft are grasped, and this is made constant. While controlling the weaving machine angle (hereinafter referred to as the start angle) to start the weft insertion operation so as to maintain the operation, the operation of the start angle control system is temporarily reset at the time of yarn feeding change, and the flying characteristics are controlled. A technique for coping with discontinuous fluctuations is also known (Japanese Utility Model Laid-Open No. 60-136379).

However, according to the former of the prior art,
Since the injection pressure of the main nozzle, etc. is changed in order to cope with fluctuations in the flight characteristics, the response is insufficient, and the problem that the stepwise fluctuations in the flight characteristics due to yarn feed change cannot be accommodated at all. It was inevitable. In the case of the latter, the change in the starting angle is sufficiently responsive and there is no problem with the responsiveness, but since the injection pressure is kept constant, if the flying characteristics further fluctuate for some reason,
The start angle is excessively shifted, and the temporal balance between the weft insertion operation and the warp shedding operation is broken, so that there is a possibility that a so-called warp catch or a weft insertion defect such as a breakage of the weft may be caused.

Accordingly, an object of the present invention is to provide a feedforward control for the latter when changing the yarn supply by using both the injection pressure control and the start angle control in view of the problem of the related art, and to follow the latter with the latter. To provide a weft insertion control device for a loom that can cope well with fluctuations in all flight characteristics, including stepwise fluctuations caused by yarn feed change, and that does not cause a weft insertion defect. It is in.

Means for Solving the Problems To achieve the above object, a configuration of the present invention includes a pressure correction unit attached to a pressure controller for controlling the injection pressure of a weft insertion nozzle, and a timing controller for controlling the start timing of the weft insertion operation. The pressure correction unit outputs a pressure correction amount corresponding to the fluctuation of the weft flight characteristics to the pressure controller, while the angle correction unit responds to the yarn feed change signal, The gist is to output an angle correction amount based on a predetermined correction pattern to the timing controller.

Note that the angle correction unit may be a function generator that generates a predetermined angle correction amount according to any one of the elapsed time after the generation of the yarn supply change signal, the number of picks, and the winding diameter of the yarn supply body.

Further, a limiter element may be provided on the input side of the timing controller, and a dead band element may be provided on the input side of the pressure controller.

Furthermore, the timing controller can be provided with an angle correction unit that outputs an angle correction amount according to the fluctuation of the weft flight characteristics.

According to the configuration of the present invention, when the flight characteristics of the weft change due to a cause other than the yarn feeding change, the pressure correction unit sends a pressure correction amount corresponding to the change in the flight characteristics of the weft to the pressure controller. Correct the injection pressure of the main nozzle and the like.

At the time of yarn supply change, the flight characteristics change suddenly step by step because the yarn supply body is switched. Therefore, when a yarn feed change is detected based on the yarn feed change signal, the angle correction unit outputs an angle correction amount corresponding to the fluctuation width of the flight characteristics at that time to the timing controller, and corrects the start angle. Since the correction of the start angle at this time is performed by the yarn feed change signal, it can be reliably applied even when the weft from the new yarn feeder after the yarn feed change is first inserted into the weft, and a kind of Feedforward control can be performed. Since the angle correction amount subsequently returns to the zero level according to the predetermined correction pattern, the pressure correction unit and the pressure controller can correct the injection pressure sufficiently following the change in the angle correction amount. As a whole, it is possible to cope with fluctuations in flight characteristics due to yarn supply change.

The correction pattern of the angle correction amount generated by the angle correction unit is
In general, when a yarn feed change signal is generated, a fixed angle correction amount corresponding to the fluctuation width of the flight characteristics of the weft due to yarn feed change is generated, and then the angle correction amount is adjusted so that the pressure controller can follow. What is necessary is just to return to zero level slowly. Since the correction pattern of the angle correction amount should depend on the elapsed time after the yarn feed change signal is generated, the elapsed time itself is used, and the number of picks of the loom and the winding diameter of the yarn feeder are used. As a result, more accurate control can be realized.

If a limiter element is interposed on the input side of the timing controller, the limiter element prevents the command start angle from deviating extremely even when a large angle correction amount or angle correction amount occurs, and weft insertion operation There is no fear that the timing balance between the warp opening operation and the warp opening operation is lost.

In addition, if a dead band element is interposed on the input side of the pressure controller, the dead band element eliminates the response of the pressure controller to a minute pressure correction amount, and mechanical parts such as a pressure regulating valve are unnecessarily worn. There is no.

If you add an angle correction unit to the timing controller,
The angle correction unit sends an angle correction amount corresponding to the fluctuation of the weft flight characteristics to the timing controller, and can correct the weft flight state quickly by first changing the start angle. At the same time, the pressure correction unit sends the pressure correction amount to the pressure controller to correct the injection pressure.

The pressure controller at this time does not have a fast response, but operates independently of the timing controller so as to realize an injection pressure suitable for the weft flight characteristics. It is corrected until it shifts according to the variation in running characteristics. Therefore, as the injection pressure is corrected in this manner, the angle correction unit works in a direction to return the start angle to the normal set start angle, and therefore, finally, only the injection pressure changes the flight characteristics of the weft. The stable weft insertion operation can be continued with the regular set start angle and set arrival angle. In addition,
Since the angle correction unit operates based on the flight characteristics of the actually inserted weft, it cannot respond to the first weft insertion after changing the yarn supply. Can be dealt with in advance.

Embodiments Hereinafter, embodiments will be described with reference to the drawings.

The weft insertion control device of a loom mainly includes a pressure controller 10, a timing controller 20, a pressure correction unit 30, an angle correction unit 40, and an angle correction unit 60 (first example).
Figure).

The loom is an air jet loom (Fig. 2), and the yarn feeder
The weft W unwound from W1 is inserted into the warp opening WP via a drum type weft measuring and storing device (hereinafter simply referred to as a storing device) D and a main nozzle MN. Along the running path of the weft W, sub-nozzles SNi, SNi... (I = a, b... N) are arranged in a plurality of groups. However, the yarn feeder W1
Is connected to the end of winding of the spare yarn supplying body W2, and when all of the former winding amount is consumed, the supply source of the weft W automatically shifts to the latter. Also, in order to detect the occurrence of the yarn feed change at this time, the yarn feed change sensor TS
Is provided.

The storage device D is provided with a locking pin D1 and an unwinding sensor D2. Weft W wound and stored around drum D3
Are the weft insertion signals Sd, S from the timing controller 20
The locking pin D1 is driven to the unwinding position by m, Ssi (i = a, b... n), and the on-off valves Vm, Vsi (i = a, b.
n) is opened and the main nozzle MN and the sub-nozzles SNi, SNi are operated by weft insertion, and the weft insertion length Wn is
It is measured by the unwinding sensor D2.

The main nozzle MN and the sub-nozzles SNi, SNi ... share a common air source A via on-off valves Vm, Vsi, pressure regulating valves PVm, PVs, respectively.
C, and the respective injection pressures Pm and Ps are controlled by control signals Spm and Sps from the pressure controller 10. Also, on the opposite side of the woven fabric, the weft W
An arrival angle sensor ES is provided to detect the arrival angle θe of the loom, and the loom mechanical angle θ from the encoder EN is input to the timing controller 20.

The pressure controller 10 includes a set injection pressure Po from an injection pressure setting device (not shown) and a pressure correction amount from the pressure correction unit 30.
An addition point 11 for inputting Pc and two control amplifiers 12,
12 (see FIG. 1). The output of the pressure controller 10 is used as a control signal Spm, Sps as a pressure regulating valve.
Entered in PVm and PVs. However, the set injection pressure Po,
The pressure correction amount Pc is input to the addition terminal and the subtraction terminal of the addition point 11, respectively. Also, here, the sub nozzle
The control system on the loom side for SNi, SNi... Is not shown.

The timing controller 20 continues the addition point 21 and the controller main body 22. A setting start angle θso from a start angle setting device (not shown) and an angle correction amount θc from the angle correction unit 40 are input to an addition terminal and a subtraction terminal of the addition point 21 respectively. The controller body 22 compares the command start angle θs = θso−θc from the addition point 21 with the loom mechanical angle θ from the encoder EN, and outputs the weft insertion signal S.
By outputting d, Sm, and Ssi, weft insertion is started at θ = θs. That is, the timing controller
20 is a locking pin D1, a main nozzle MN, a sub nozzle SNi, SNi…
When the weft insertion length Wn from the unwinding sensor D2 reaches a predetermined value, the weft insertion is completed.

The pressure correction unit 30 and the angle correction unit 40 are provided before the pressure controller 10 and the timing controller 20, respectively (FIGS. 1 and 2).

The pressure correction unit 30 includes an addition point 31 and a pressure correction unit 32, and a set flight period τo from a flight period setting device (not shown) is input to the former addition terminal, while a subtraction terminal is The flight period τ of the weft W from the flight period calculation means 51 is input. The pressure correcting means 32 includes a PID control element, and the flight period deviation Δτ = τo from the addition point 31.
−τ is input, the pressure correction amount Pc is calculated, and output to the pressure controller 10. In addition, the flight period calculation means 51 calculates the command start angle θs = θso−θ from the timing controller 20.
c and the arrival angle θe from the arrival angle sensor ES, and the flight period τ = θ of the weft W in units of the loom mechanical angle θ.
e-θs is calculated and output.

The angle correction unit 40 includes an addition point 41 and an angle correction unit 42. The addition point 41 inputs a set arrival angle θeo and an arrival angle θe of the weft W from an arrival angle setting device (not shown) and outputs an arrival angle deviation Δθe = θeo−θe. Enter the deviation Δθe and set the appropriate PI
The timing controller 2 calculates the angle correction amount θc through the D operation.
Output to 0.

The yarn feed change signal St from the yarn feed change sensor TS is input to the angle correction unit 60. The output of the angle correction unit 60 is the angle correction amount θct as the addition point of the timing controller 20.
21 are input to another subtraction terminal.

Now, when the weft insertion operation is performed normally, the weft W is set by the timing controller 20 at the set start angle θ.
The weft insertion starts at so, and reaches the anti-weft insertion side at the set arrival angle θeo. That is, at this time, since the arrival angle θe = θeo, the arrival angle deviation Δθe = θeo−
θe = 0, and therefore, the angle correction amount θc from the angle correction unit 40 is θc = 0.

At this time, the flight period τ of the weft W is τ = τo, and therefore the pressure correction amount Pc from the pressure correction unit 30 is obtained.
Also, Pc = 0. Therefore, the injection pressures Pm and Ps from the main nozzle MN and the sub-nozzles SNi and SNi, which are realized by the pressure controller 10 and the pressure regulating valves PVm and PVs, are also set at the set injection pressure.
Matches Po.

If the flight characteristics of the weft W decrease for some reason, the flight period τ of the weft W becomes τ> τo (FIG. 3), and the arrival angle θe also lags behind the set arrival angle θeo and θe> θeo. Therefore, the addition point 41 of the angle correction unit 40 detects the arrival angle deviation Δθe = θeo−θe <0, and outputs it to the angle correction unit 42. The angle correction means 42 calculates θ = f (Δθe)
> 0 (where f is a control function including a part or all of the PID element), the angle correction amount θc is calculated and output to the timing controller 20, so that the timing controller 20 By starting weft insertion at the command start angle θs = θso−θc <θso using the amount θc, the arrival angle deviation Δ
θe can be eliminated.

On the other hand, the flight period calculation means 51 calculates the flight period τ at this time.
> Τo and outputs it to the pressure compensating unit 30, so that the addition point 31 of the pressure compensating unit 30 has a flight period deviation Δτ = τo−τ
<0 is output to the pressure correcting means 32. The pressure correction means 32
Since the pressure correction amount Pc is calculated as Pc = g (Δτ) <0 (where g is a control function including a part or all of the PID element) and output to the pressure controller 10, the pressure controller 10 The pressure Po is corrected in the direction in which the flight period deviation Δτ is eliminated, and the command injection pressure P = Po−Pc
> As Po, pressure regulating valve PV via control amplifiers 12 and 12
Output to m and PVs. That is, when the flight period deviation Δτ <0, the correction direction is selected so that the command injection pressure P> Po. As a result, the pressure regulating valves PVm and PVs are connected to the main nozzle MN,
The injection pressures Pm and Ps from the sub-nozzles SNi, SNi ... are Pm = Ps =
Modify so that P> Po.

When the injection pressures Pm and Ps are corrected in this way, the flight period τ can be corrected to the set flight period τo.
Here, the pressure controller 10 including the pressure regulating valves PVm and PVs
Is generally much slower than that of the timing controller 20, and as the flight period τ is corrected, the angle correction unit 40 changes the arrival angle θe to the set arrival angle θ.
By maintaining eo, the command start angle θs works to return to the set start angle θso. That is, the command start angle θs can be returned to the set start angle θso so as to follow the correction of the injection pressures Pm and Ps by the pressure controller 10, and finally, the injection pressures Pm and Ps are surely Pm = Ps
= P, and correspondingly, the command start angle θs
Can return to θs = θso.

The flight characteristics of the weft W become higher, and the arrival angle θe becomes θe <
When it shifts in the direction of θeo and the flight period τ becomes τ <τo, the above description is reversed, and finally the injection pressure Pm,
As for Ps, Pm = Ps = P <Po is achieved, and the command start angle θs is θ
It returns to s = θso.

When the yarn feeder W1 is consumed and the yarn feed change is performed, the yarn feed change signal St is generated from the yarn feed change sensor TS, and the angle correcting unit is generated.
60 works. Now, the weft W from the inner layer of the yarn supplying body W1
Assuming that the flight characteristics are better than those from the outer layer portion of the yarn supply W2, the flight characteristics of the weft W will be changed in the direction in which the flight period τ is extended by changing the yarn supply. Changes suddenly in stages. Therefore, at this time, the angle correction unit 60 outputs the yarn feed change signal.
After the occurrence of St, after a slight time delay td, the angle correction amount θct =
A function generator having a correction pattern that generates Δθct and thereafter returns the angle correction amount θct to a zero level with the passage of time t may be used (FIG. 4). Angle correction amount θct
Is input to the addition point 21 of the timing controller 20, the command start angle θs = θso−θc by setting the value of the angle correction amount θct = Δθct according to the variation width of the flight characteristics of the weft W. −θct can be modified so that the reaching angle θe of the weft W is maintained at the set reaching angle θeo.

At this time, the pressure correction unit 30 and the pressure controller 10
Is the flight period τ of the weft W in exactly the same manner as described above.
Is operated so as to correct the injection pressures Pm and Ps in a direction in which is maintained in the set flight period τo.

In FIG. 4, the time delay td is set so as to correspond to the time difference from the operation of the yarn feed change sensor TS to the actual weft insertion of the weft W from the new yarn feeder W2. Further, the time Δt for returning the angle correction amount θct to the zero level is set to be sufficiently long so that the pressure controller 10 can follow.

In this way, after the yarn feed change signal St is generated, the injection pressure
Pm and Ps become higher than the set injection pressure Po by a pressure difference ΔP corresponding to the fluctuation width of the flight characteristics due to the yarn supply change over time Δt (strictly, time (td + Δt)).
The angle correction amount θct from the angle correction unit 60 has returned to the zero level. Therefore, the control thereafter shifts to the above-described steady control, and stable weft insertion can be continued while responding to the fluctuation of the flying characteristics accompanying the consumption of the new yarn supplying body W2.

In addition, when the fluctuation direction of the flight characteristics of the weft W due to the yarn supply change is reversed, the sign of the angle correction amount θct = Δθct may be reversed.

In the above description, the maximum value Δθct of the angle correction amount θct
Can be determined, for example, as follows. First, a trial weaving is performed without operating the pressure compensating unit 30 in a state where the yarn supplying body W1 has a large diameter.
1, 2,...). For each command injection pressure Pj, if the command start angle θsj (j = 1, 2,...) For the arrival angle θe to be θe = θeo is determined, the relational expression of the command start angle θsj with respect to the injection pressure Pj can be determined. it can.

Therefore, in the case of the main weaving, the pressure correction unit 30 is operated, and when the injection pressure Pa that satisfies θe = θeo is obtained immediately before the yarn feed change, the command start angle corresponding to the injection pressure Pa is referred to by referring to the above-mentioned relational expression. What is necessary is just to determine (theta) sa and make (DELTA) (theta) ct = (theta) sa- (theta) so. However, the relational expression between the injection pressure Pj and the command start angle θsj at the stage of the trial weaving may be obtained automatically by using the angle correction unit 40, or may be obtained through manual trial.

The maximum value Δθct may be a constant when the injection pressure Pa immediately before the yarn feed change is constant, but when the injection pressure Pa may fluctuate, the relational expression of the command start angle θsj with respect to the injection pressure Pj. Is provided in the angle correction unit 60, and the maximum value Δθct is preferably variably set by inputting the command injection pressure P = Pa immediately before the yarn feed change into the function generator.

Another Embodiment The angle correction unit 60 can be formed by a function generator 62 (FIG. 5). The function generator 62 outputs the yarn feed change signal St.
And the angle correction amount θct based on a predetermined correction pattern corresponding to the pick number np of the loom thereafter.
Is output. The number of picks np can be measured using a pick signal Sp from a pick sensor (not shown) that detects a beating movement. Note that the pick signal Sp may be obtained from a sensor that detects the momentum of any moving member including the main shaft of the loom.

The angle correction unit 60 is provided with a winding diameter sensor facing the yarn feeders W1 and W2.
Even if the function generator 64 is provided with RS1 and RS2 and outputs an angle correction amount θct based on a predetermined correction pattern corresponding to the winding diameter Rw of the yarn feeder Wi (i = 1, 2) in use. Good (6th
Figure). Here, the yarn feed change signal from the yarn feed change sensor TS
St is input to a switch 63 interposed between the winding diameter sensors RS1 and RS2 and the function generator 64, and the switch 63 functions as a function of the winding diameter Rw of the yarn supply Wi on the side currently being used. It can be selectively supplied to the generator 64.

In each of the above embodiments, the angle correction amount θct may be slowly returned to the zero level after the generation of the yarn feed change signal St until the entire amount of the new yarn supply Wi is consumed. Also,
When it is known that the change in the flight characteristics inside the yarn supplying body Wi draws a constant curve with respect to the winding diameter Rw, the angle correction amount θct is changed along an arbitrary curve conforming to this curve. You may.

The angle correction amount θc from the angle correction unit 40 and the angle correction amount θct from the angle correction unit 60 are the addition point 52 and the limiter element 53.
(FIG. 7). There is no possibility that the command start angle θs is extremely shifted and the timing balance between the weft insertion operation and the warp shedding operation is lost.

A dead band element may be interposed between the pressure correction unit 30 and the pressure controller 10. Since the dead band element does not send the minute pressure correction amount Pc within the dead band width to the pressure controller 10, the pressure controller
10 and the associated pressure regulating valves PVm, PVs can minimize the chance of performing unnecessary small operations.

In the above description, the main nozzle MN, the sub nozzles SNi, S
The injection pressures Pm and Ps of Ni are not always set to Pm = Ps = P, but Pm = aPs (a is set by interposing an appropriate ratio setting element on the input side of the control amplifiers 12 and 12, for example. Pm ≠ Ps may be used as a constant that is not 1). Also, a pressure regulating valve
The PVs may be provided for each group of the sub-nozzles SNi, SNi... And realize different injection pressures for each group. That is, the injection pressure of each weft insertion nozzle composed of the main nozzle MN, the sub-nozzles SNi, SNi...
The main nozzle MN alone or the sub-nozzles SNi, SNi... Can be divided into arbitrary groups to be controlled by the pressure controller 10.

Further, the overall control system shown in FIG. 1 including the pressure correction unit 30, the angle correction unit 40, and the angle correction unit 60 can be realized by any of an analog system and a digital system. Can be operated in response to the picking operation. Furthermore, in the latter, the flight period deviation Δτ,
The arrival angle deviation Δθe may be calculated for each pick based on a moving average value of the flight periods τ, τ..., The arrival angles θe, θe. It may be calculated for each fixed number of picks based on the value.

In FIG. 1, the set flight period τo is obtained from a flight period setting device (not shown), but τo = θeo−
It may be calculated as θso. Also, the set flight period τo,
The flight period τ may be a time parameter instead of an angle parameter. At this time, the flight period calculation means 51 measures the time difference from the command start angle θs to the arrival angle θe, and the set flight period τo is
A value corresponding to the time required for the weft W to fly normally is set. Further, the pressure correction unit 30 may use the arrival angle θe as a feedback signal instead of the flight period τ. Similarly, the angle correction unit 40 replaces the reaching angle θe with
The flight period τ may be used.

In the present invention, the angle correction unit 40 may omit this, and in this case, the timing controller 20
Means that the command start angle θs is controlled only by the set start angle θso and the angle correction amount θct.

Further, the timing controller 20 determines the loom machine angle θ
= Θs, instead of simultaneously operating the weft insertion members including the main nozzle MN, the sub nozzles SNi, SNi..., And the locking pin D1, an appropriate time difference may be set in the operation timing of these weft insertion members. That is, the operation of the main nozzle MN may be started before the operation of the locking pin D1 by a predetermined time, or vice versa.

Effects of the Invention As described above, according to the present invention, the pressure controller and the timing controller are provided with the pressure correction unit and the angle correction unit, respectively. The amount of angle correction based on the correction pattern is output to the timing controller. Because it can be used together, fluctuations in all flight characteristics including when changing yarn supply,
There is an excellent effect that it is possible to easily continue a sufficiently stable weft insertion operation without fear of occurrence of a weft insertion defect.

[Brief description of the drawings]

1 to 4 show an embodiment, FIG. 1 is an overall system diagram, FIG. 2 is a conceptual diagram of the entire configuration, and FIGS. 3 and 4 are operation explanatory diagrams. FIG. 5 to FIG. 7 are main part system diagrams showing different embodiments. W: Weft Pm, Ps: Injection pressure St: Yarn feed change signal Pc: Pressure correction amount θc: Angle correction amount θct: Angle correction amount 10: Pressure controller 20: Timing controller 30: Pressure Correction unit 40 Angle correction unit 53 Limiter element 60 Angle correction unit 62, 64 Function generator

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁶ , DB name) D03D 47/28-47/38 D03D 51/00

Claims (7)

(57) [Claims] 1. A pressure correction unit attached to a pressure controller for controlling the injection pressure of a weft insertion nozzle, and an angle correction unit attached to a timing controller for controlling a start timing of the weft insertion operation, wherein the pressure correction unit is Outputting a pressure correction amount corresponding to a change in the flight characteristics of the weft to the pressure controller, while the angle correction unit sets the angle correction amount based on a predetermined correction pattern in accordance with the yarn feed change signal with the timing. A weft insertion control device for a loom characterized by outputting to a controller. 2. The loom according to claim 1, wherein said angle correcting section comprises a function generator for generating a predetermined angle correcting amount in accordance with an elapsed time after the generation of the yarn feed change signal. Weft insertion control device. 3. The loom according to claim 1, wherein said angle correction section comprises a function generator for generating a predetermined angle correction amount according to the number of picks after the yarn feed change signal is generated. Weft insertion control device. 4. The angle correction unit according to claim 1, wherein said angle correction unit comprises a function generator for generating a predetermined angle correction amount in accordance with the winding diameter of the yarn supply after the yarn supply change signal is generated. A weft insertion control device for a loom according to the above. 5. The weft insertion control device for a loom according to claim 1, wherein a limiter element is interposed on an input side of said timing controller. 6. A weft insertion control device for a loom according to claim 1, wherein a dead band element is interposed on an input side of said pressure controller. 7. The timing controller according to claim 1, wherein said timing controller is provided with an angle correction unit for outputting an angle correction amount corresponding to a change in the flight characteristics of the weft. The weft insertion control device for a loom according to any one of the above.